WO1987006304A1 - I.c. engine with deck parting line intermediate of cylinder block - Google Patents

Abstract

Improvements to the construction of reciprocating internal combustion engines which assist in ease of servicing and avoids failure problems associated with head gaskets, the construction including a number of cylinders (1), a crankshaft (2), connecting rods (17) joining the crankshaft to piston members (20) located for reciprocating in the cylinders (1), a crankcase (8) is provided for mounting the crankshaft and for locating lower ends of the cylinders (1) therein, and a cylinder head (10) provided for locating upper ends of the cylinders (1) therein, the dividing line between the cylinder head (10) and the crankcase (8) being located part way along the cylinders (1) and the cylinders (1) being formed by liner members (6) extending into both the crankcase (8) and the cylinder head (10).

Description

I.C. ENGINE WITH DECK PARTING LINE INTERMEDIATE OF CYLINDER BLOCK

The present invention relates to reciprocating internal combustion engines and more particularly to various improved aspects of such engines.

Over the past thirty years, the operation and design of reciprocating internal combustion engines has reached a stage where certain basic design features have become enshrined to such an extent that little questioning is made of their value. More recently, large amounts of time and expense have been made in investigating alternative engine formats such as gas turbines, rotary engines, orbital engines, steam engines and the Stirling engine based on the broadly held view that the reciprocating engine has reached the limits of its development.

The objective of the present invention is to provide a number of improved aspects applicable to reciprocating internal combustion engines aimed at improving the operational performance and serviceability of such engines .

According to a first aspect of the present invention there is provided a reciprocating internal combustion engine comprising a plurality of cylinders, a crankshaft, connecting rods pivoted to said crankshaft and to piston members adapted for reciprocation in said cylinders, said engine being characterized by a crankcase generally surrounding said crankshaft and lower regions of said cylinders and a cylinder head generally surrounding upper regions of said cylinders with a dividing face between said crankcase and said cylinder head meeting part way along the longitudinal length of said cylinders, and said cylinders being formed by liner members having a cylindrical bore receiving a respective said piston member. Conveniently said liner members abut against annular ledges in said crankcase and said cylinder head. Preferably a spring means is provided, such as an annular wave spring, acting between a lower edge of the liner member and the annular abuttment ledge in the cra.nk case where-by the liner member is urged upwardly against a complementary annular ledge in the cylinder head and is thereby sealed to the combustion chamber.

In accordance with a particularly preferred _j- arrangement the end of the liner member engaging the cylinder head is formed to provide a line point of contact against the cylinder head. This enables a higher sealing pressure to be established along this line of contact than could be achieved by a surface sealing area. In one

- _n arrangement the end of the liner member might be chamfered on one or both the inner and outer edges. In another arrangement an annular projection might be provided on the end of the liner member. In a third embodiment, an annular seal member (piano wire or the like) might be held in a

₁.. groove in the end of the liner member such that the seal member itself engages along the line point of contact against the cylinder head. The arrangement of the engine according to the foregoing renders possible the servicing of the engine piston and cylinder line assembly by removal of

__n the cylinder head and avoids the need for head gaskets which are prone to failure and allow coolant to contaminate the lubricant.

According to a second aspect of the present invention there is provided a reciprocating internal _ς combustion engine comprising a plurality of cylinders forming an in-line cylinder set driving a crankshaft with power take off occurring from a laterally off set shaft driven by a gear train from said crankshaft. According to an alternative embodiment of this aspect the engine may

,_n comprise two side by side cylinder sets, each set with its own crankshaft driving a common power take off shaft through gear train meansfrom the said crankshafts. Preferably each set comprises three cylinders. Preferably the said power take off shaft is a quill shaft made inside of and coaxial

__ with a camshaft provided for giving operational movement to inlet and exhaust valves of the engine.

The present invention also recognises the need for an improved method of controlling engine temperatures and at the same time recognizes the serious complications created by using separate and incompatible fluids for cooling and lubrication in conventional engines.

According to this further aspect the present invention proposes a reciprocating internal combustion engine comprising storage means for maintaining a supply of a single fluid adapted to act both as a temperature control medium and as a lubricant, and circulation means for circulating said fluid throughout said engine. Conveniently said fluid is stored in said storage means after circulation through passage means and appropriate spaces in said engine. Preferably heat dissipation means such as one or more heat exchangers is^' provided acting on fluid leaving said storage means ρ_ior to its entering the cooling and lubricating passages in the engine. The cooling effect provided by said cooling means is made variable in response to the temperature of fluid draining immediately from the crankcase of the engine. In this respect temperature sensing means may be provided to sense the temperature of the fluid in the crankcase or as the fluid is drained from said crankcase towards the storage means.

In accordance with one preferred embodiment the aforesaid fluid storage means comprises a storage housing arranged immediately beneath the engine construction with the interior of the storage housing in fluid communication with at least one drain back aperture leading from the engine. Preferably the storage housing comprises at least two compartments, the major one of which includes fluid heat dissipation such as heat exchanger elements and another smaller one of which includes no such fluid cooling means and from which the supply to the fluid circulation pump is derived. Conveniently temperature sensitive valve means is provided to direct the fluid draining to said storage housing to one or other of said compartments in response to the temperature of the coolant draining from the engine. If the engine is cold and the fluid draining from the engine is also relatively cold, the fluid is directed to the said smaller compartment from which it is immediately returned to the engine to promote rapid warm up of the fluid and therefore the engine. When the engine is hot, the fluid draining back is equally hot and is directed by said valve means to the said major compartment wherein the fluid is maintained at an optimum temperature for return to the engine. In accordance with a particularly advantageous embodiment there is provided a small central compartment with no cooling means and two compartments on either side of the said central compartment, each including heat dissipation means. In this arrangement the fluid return to the engine is taken from the first central compartment and fluid transfer passages or openings are provided leading from the outer compartments to the central compartment so that fluid can be transferred thereto after passage past the heat dissipation located in the outer compartments. Preferably, fluid draining from the engine is collected in substantially one space or region from where it drains to the storage housing via passages or spaces including de-aeration areas such as open foam, expanded metal or metal fibre structures.

In accordance with a further aspect of this invention, there is provided heat exchanger means in the form of an engine flywheel for controlling heat dissipation from a fluid coolant in an internal combustion engine, said flywheel defining passages for the transference of said fluid coolant through the body of said flywheel while passing cooling air over at least a portion of the outer surface of said flywheel. Conveniently the flywheel comprises a central boss a radially and circumferentially extending web and an outer rim defining at least one shallow annular space. A finned thin-walled metal (of good heat transference properties such as copper) structure is located within said shallow annular space and defines inner and outer generally annular fluid collecting spaces connected by transference passages in the form of vanes extending from a position adjacent the web towards the free edge of the rim of the flywheel. Conveniently return fluid passages are provided in said thin-walled metal structure to return the fluid from said outer annular space to passage means located in the boss of the flywheel. In a preferred embodiment of an engine described in the foregoing, fluid coolant is drawn from a storage tank by pump means driven by the crankshaft through suitable gearing means, the fluid coolant passing from said pump means through a hollow quill shaft made coaxial with a camshaft for the engine into the central boss of the aforesaid flywheel. The flywheel being conveniently mounted on the end of and driven by said hollow quill shaft. Preferably the aforesaid pump means is formed in part by a power take off shaft of the engine.

In accordance with another aspect of the present invention there is provided a novel form of crankshaft for a reciprocating internal combustion engine. According to this aspect there is provided a crankshaft comprising a plurality of main shaft portions, a plurality of crank pin portions generally parallel to said main shaft portions but off set laterally therefrom and said crank pin portions being angularly spaced relative to each other, and a plurality of crankshaft webs joining the end of each crank pin portion to an end of a main shaft portion, said crankshaft portion being characterized by internal passage means for the passage of a temperature control fluid extending fully along the length of said crankshaft. Preferably said crankshaft webs are made substantially circular in cross section with portions of said webs opposite said crank pin portions being made solid to provide a counter balance effect to the said crank pin portions and the connecting rods carried thereon. Conveniently one end of the crankshaft may be directly coupled to pump means adapted to receive and pump fluid coolant through the crankshaft.

According to a further aspect of the present invention there is provided an improved novel cylinder head arrangement for a reciprocating internal combustion engine. Conveniently the cylinder head arrangement comprises a plurality of spaces defining the upper ends of combustion chambers, each said combustion chamber having an exhaust port leading therefrom together with an exhaust valve for controlling flow through said exhaust port, and at least two inlet ports for introducing a combustible charge into said combustion chamber controlled by two inlet valves.

Preferably spring means are provided associated with each of said inlet and exhaust valves to bias said valves to a normally closed position. Conveniently shaft mounted rockers, cam actuated via p ^fush rods,' are p frovided to control the timed opening and closing of said inlet and exhaust valves .

In an advantageous embodiment, a first one of the inlet ports of each said combustion chamber are connected to a first common inlet manifold runner while the other of the inlet ports of each said combustion chamber are connected to a second common inlet manifold runner. Preferably a small auxiliary inlet manifold is provided with passage means leading to one only of the inlet ports of each combustion chamber. Diversion passage means may be provided leading from carburetion means into heat exchange relationship with heated exhaust gases and thence to said auxiliary inlet manifold. As a result the auxiliary inlet manifold provides vapourized fuel/air mixture to the combustion chambers during idle and off idle. ^y

Preferably said inlet and exhaust valves are operated from separate rocker arms carried on a single rocker shaft, the rocker arms operating the inlet valves being bifurcated and actuated by push rods from a remote camshaft. Conveniently-r sprring^■_^> means act between said rocker arms on said rocker shaft tending to urge the valve train components in a direction whereby said inlet and exhaust valves are moved to a valve closed position thereby supplementing the conventional valve closing springs associated with each of the inlet and exhaust valves.

It will be appreciated from the foregoing and the following description that the various aspects of this invention might be used independently on their own or in any form of combination with each other. The various aspects will be better understood from the following description of preferred embodiments given in relation to the accompanying drawings, in which:

Figure 1 is a transverse section through an engine in accordance with a preferred embodiment of this invention in which the position of certain of the components is shown in broken line;

Figure la is a detail transverse section of the cylinder head of the engine shown in Figure 1;

Figure 2 is a longitudinal sectional view of the engine camshaft and flywheel showing certain associated components according to preferred embodiments of this invention;

Figure 3 is a longitudinal sectional view of the forward end of an engine crankshaft showing certain associated components;

Figure 4 is a longitudinal sectional view of the rear end of an engine crankshaft showing certain associated components ;

Figure 5 is a transverse section along line A-A of Figure 4;

Figure 6 is a face view of the arrangement of a housing for a crankshaft centre main bearing according to a preferred aspect of this invention;

Figure 7 is a partial sectional view of an engine crank tunnel showing the arrangement of the crankshaft centre main bearing housings shown in Figure 6;

Figure 8 is a longitudinal sectional view along line C-C of Figure 9 of an engine balance shaft with its drive and support means;

Figure 9 is a transverse section along line B-B of Figure 8;

Figure 10 is a sectional view of the forward end of an engine crankcase casting illustrating an arrangement by which the forward cylinder head bolts are secured to it. Figure 11 is a frontal view of the engine illustrating schematically an arrangement of a gear train;

Figure 12 is a plan view of the gear train depicted in Figure 11;

Figure 13 is a view of the underside of the engine with the oil pan removed;

Figure 14 is a rear view of the engine crankcase casting showing how the rear cylinder head bolts are secured to it;

Figure 15 is a plan view of the top of the engine crankcase with the cylinder head removed;

Figure 16 is a view of the underside of the cylinder head including the combustion chambers;

Figure 17 is a plan view of part of the upper face of the cylinder head with the rocker cover removed;

Figure 18 is a plan view of the engine cylinder head with a superimposed diagram showing the arrangement of the inlet manifold runners;

Figure 19 is a sectional view of an arrangement to supply vaporised fuel to an auxiliary inlet manifold;

Figures 20, 21 and 22 are views of the arrangement of the engine exhaust manifold;

Figure 23 is a vertical sectional view of an arrangement to supply cooling air to the flywheel and oil pan heat exchangers with details of the crankshaft being omitted;

Figure 24 is a sectional view of an arrangement to supply vaporised fuel-air mixture to a single cylinder for extended idle;

Figure 25 is a vertical sectional view of the coolant circulation paths around and through a cylinder head to main bearing bolt; and

Figure 26 is a longitudinal sectional view through the centre lines of the inlet valves of the upper part of one cylinder and the area above it.

With reference to Figures 1, la, 15 and 26, a piston engine is provided of a three-cylinder, in-line arrangement in which the axes of the cylinders 1 are inclined at an angle of 45 degrees to a mounting face 29 for an oil pan 30.

Crankshaft 2 is made with three throws separated in an angular sense by 120 degrees and is preferably provided with four main bearings, the outer two being double-row tapered roller bearings, and the two middle being plain journals supported in shell bearings carried in large circular bearings housings 3. With further reference to Figures 4, 5, 6 and 7, crankshaft crank webs 4 are made full-circular and are internally counter-weighted by being made with a solid sector 135 opposite and a hollow sector 136 adjacent each crank pin 32. Main bearing shafts 31 and the crank pins 32 are made hollow, said hollow parts 5 being made contiguous with said hollow parts 136 of adjacent crank webs such that a continuous flow path is created throughout the length of the said crankshaft. The strengthening members 159 located in hollow parts 136 in the crank webs serves to transfer stresses from the crank pins 32 to adjacent said main bearing shafts. Said hollow part in said main bearing shaft is plugged at each side of the said crank webs by screwed plugs 14. The said crankshaft configuration of three throws separated by 120 degrees provides good balance characteristics. The said arrangement of full-circular, internally-counterweighted crank webs provides minimal rotational drag and excellent strength, permits the use of a lighter flywheel, provides ease of balancing and reduced torsional vibration. Said hollow areas or internal passages 5, 136 facilitate cooling of the said crankshaft bearings. As a result closer bearing clearances can be employed whereby design advantages can be obtained.

Cylinder liners 6 are fitted into bores 7 in crankcase casting 8 in a light sliding fit. The said cylinder liners extend into the bores 9 of the cylinder head casting 10, also in a light sliding fit. The upper edges of said cylinder liners 6 abut annular machined faces 11 in the said cylinder head casting, whilst their lower edges bear against a stiff wave spring 12 supported by annular machined faces 13 at the bottom of bores 7 in the said crankcase casting. The accomodation of the cylinder liners partly in the said cylinder head and partly in the said crankcase confers great ease of dismantling. Removal of the said cylinder head permits immediate removal of the said cylinder liners and, as the said gudgeon pins are above the top deck of the said cylinder block, the removal of the said pistons also. Moreover the construction as illustrated includes 10 downwardly and upwardly extending processes 44 and 45 on the cylinder head casting 10 and the crankcase casting 8 respectively. This arrangement enables the depths of the processes 44, 45 to be varied during manufacture to accommodate cylinder liners 6 of greater or smaller length as desired. Moreover the relatively narrow width of the lands formed by processes 44, 45 provide a restricted heat flow path from the cylinders.

Preferably, parting face 15 of big end cap 16 of connecting rod 17 is angled to facilitate access to big end

20 ^{y 3 y} bolts 18 through access slots 19 in a lower wall of the said crankcase casting. Preferably, connecting rod 17 is cast or forged from a strong, light-weight material in the well-known I-beam form. In an alternative embodiment, the said connecting rod is fabricated from suitable sheet, solid

_~_ D and tubular components.

Gudgeon pins 34 are made hollow, the diameter of the said hollow part being increased towards each end of the pin for lightness. Said gudgeon pins are made fully floating, being retained in their bores by suitable circlips or plugs. Said gudgeon pin bores are slightly offset towards the major thrust face of the said piston to minimise piston slap in the manner well-known in the art. Pistons 20 are made as strong and light as possible and ^'are provided with two piston ring grooves to accomodate compression 35 piston ring 21 and oil control piston ring 22. As best seen in Figure la, the head of each of said pistons 20 is made with a rounded shoulder 35 of generous radius, a narrow. flat, annular squish band 36 inwardly of which is positioned dished crown 37 forming a lower combustion chamber face.

Crankcase casting 8 comprises a more or less cylindrical crank tunnel 23 upon which is superimposed an upwardly extending part 24 in which the lower part of the depth of cylinder liners 6 is accomodated, and lateral extension 25 which accomodates lubricant drainback gallery 26, camshaft 27 in its tunnel and balance shaft 28 in its gallery. The said drainback gallery may be filled with a suitable open foam, expanded metal or metal wool to facilitate de-aeration of drainback oil. Lower faces of crank tunnel 23 and lateral extension 25 are made flat and contiguous to form the single mounting face 29 for the oil pan 30.

With further reference to Figure 2 , camshaft 27 is made coaxial with a hollow quill shaft 33, sufficient clearance being provided between them to permit independent torsional movement. Said camshaft operates in cam tunnel 43 passing along the length of the said engine and is provided w ith a centrally-located bearing journal 27a which is supported against downward deflections of the said camshaft by means of part-circular bearing 38 carried at the upper end of support block 39. Cam followers 40 are carried in bores 41 in cylinder block casting lateral extension 25. Said cam followers may be solid, hollow bucket type as depicted, or in the form of hydraulic lifters, the arrangement of which is well-known in the art. The quill shaft 33, upon the end of which is mounted the engine flywheel 98, is made hollow for the purpose of transmitting coolant from one end of the engine to the other. Pushrods, the axes 42 of which are depicted, are made hollow for lightness with solid end fittings. Tappet . adjustment is effected by screwably-adjustable means of a conventional form.

Again with further reference to Figures 1, la and 16, coolant jacketing in the said cylinder head is divided longitudinally, by a web passing more or less along a plane identified by line X-X in Figure la passing more or less along the line of the inlet ports 47 and 245. The relatively hotter side 46 being the side in which the exhaust ports 54 are accomodated and the relatively cooler side 48 being that in which the said inlet ports are accomodated. Said coolant jacketing for the relatively hotter side of the said cylinder head extends substantially around the said inlet ports. Coolant in the said jacketing for the said cooler side of the said cylinder head is able to flow downward through suitable apertures 49 to fill the area enclosed by processes 44 and 45 on the lower and upper faces respectively of the said cylinder head and cylinder block castings. The upper parts of the said hotter and cooler side coolant jacketing are compartmentalised into discreet areas adjacent each cylinder by partition members

50 and 51 of the said cylinder head casting.

A flow of coolant is provided to a gallery passing along the full length of the rear of the said cylinder head by a suitable pump which draws its supply from oil pan 30 via pick-up pipe 60. From the said gallery, said coolant flows to volume tubes 52 and 53 passing along the full length of the said cylinder head beneath partition members

51 and 50 through the cooler and hotter side coolant jacketings respectively. Said volume tubes are provided with suitable drillings to direct a flow of coolant to specific areas to be cooled. Coolant from the said cooler side coolant jacketing follows a complicated path, finally exiting to the rocker compartment through hollow cylinder head bolts, the outflow from which is controlled by small thermostatic valves (these last two features being depicted as 318 and 324 in Figure 25). Coolant from the said hotter side coolant jacketing exits to the said rocker compartment through suitable drillings in the upper wall of the said cylinder head. The outer surface of the exhaust port 54 is provided with finning 55 to provide increased surface area and aid in the dissipation of heat to the coolant. The bottom wall of the hotter side coolant jacketing adjacent the said crankcase casting is provided with a plurality of apertures which are closed by welch plugs 56. The said coolant drains from the said rocker compartment via light metal pushrod tubes (not shown) which pass through the depth of the said cylinder head and are pressed into its upper and lower walls. Said drainings pass to balance shaft gallery 59 and thence to lubricant drainback gallery 26.

The crankcase is vented through a hollow balance shaft assembly 28 (depicted in Figure 8) which embodies centrifugal oil droplet separation means.

The de-aerated lubricant drainings exit the said crankcase via two drainage apertures 61 and fall to diverter plate 62. Said diverter plate is provided with a thermostatic diverter valve 63, said thermostatic diverter valve embodying valving apertures which may be brought into or out of register with complementary apertures in said diverter plate. Said thermostatic diverter valve is rotatably-operated by a bi- etallic thermostatic unit 64. When the said drainback lubricant is cool, said thermostatic diverter valve is operated by said bi-metallic thermostatic unit to direct said drainback lubricant to a hot well 65 from whence it is preferentially circulated to ensure the most rapid engine warm up. When the said drainback lubricant is hot, said thermostatic diverter valve is operated by said bi-metallic thermostatic unit to close off access to the said hot well, said drainback lubricant flooding said diverter plate and passing out through drainage apertures 66 to the periphery of the said oil pan, ensuring that it is subjected to a normal cooling process before finding its way again to pick-up pipe 60 after passing through apertures 67 in the lower wall of the said hot well.

The oil pan 30 is isolated from pressure pulses generated in the said crank tunnel by windage tray 68 which covers the whole of the lower face of the said crankcase casting excepting for lubricant drainback apertures 61 and access slots for mounting of the camshaft support block 39. Lubricant draining back from the piston area into the said crank tunnel passes to two drainage boxes 69 through limber holes 70. The drainage boxes 69 communicate with balance shaft gallery 59 through transfer pipes 71. Pressure pulses generated in the said crank tunnel act to force drainback lubricant in the said drainage boxes through the said transfer pipes from whence it is ejected onto a bi-metallic thermostatic unit (not shown) which operates a control valve (not shown) to regulate the flow of cooling air to the flywheel heat exhanger depicted in Figure 23 and the heat exchanger units 72 which are fully immersed in lubricant and pass through the length of the said oil pan. Lubricant draining back from the area of the pistons 20 and is employed to control the temperature of stored lubricant in the manner described as it is the most accurate indicator of the trend in change of engine operating temperature.

With further reference to Figures 1, la and 26, the said cylinder head is provided with one exhaust valve 57 per cylinder preferably positioned parallel to a plane normal to the axis of rotation of the said crankshaft and inclined outwards at an angle of 15 degrees to the axes of the said cylinder bores. The said cylinder head is provided with two inlet valves 58 per cylinder which are positioned parallel in all respects to the axes of the said cylinder bores. The said exhaust and inlet valves are maintained in the closed position by valve springs (not shown) which may be single or double and which are mounted and secured to the said valves in the manner well-known in the art with pads, caps and collets (not shown). The exhaust ports 54 are made short, turning through 60 degrees before meeting short stubs (depicted as 271 in Figures 20 and 21) screwed into threaded recesses in the side of the said cylinder head 10. The short exhaust stubs are adapted to accomodate the ends of individual exhaust pipes for each of the said cylinders. The axes of the said exhaust ports are made to lie in planes parallel to a plane normal to the axis of rotation of the said crankshaft. The inlet ports 47 and 245 are made in the form of shallow sig oids, the axes of the entry and exit parts of which are more or less parallel to the axes of the said cylinder bores and the plane of which is normal to the axis of rotation of the said crankshaft. Said inlet and exhaust valves are carried respectively in replaceable valve guides 73 and 74, the upper ends of which are provided with efficient stem seals 330. The parts of the said inlet and exhaust valve guides which project into the said inlet and exhaust ports are enclosed respectively in aerodynamic fairings 75 and 76. The pair of said inlet valves 58 for each of the said cylinders are operated in unison by a bifurcated rocker 77 operated by a single pushrod. Said exhaust valves are operated by rockers 78 carried on the same shaft 79 as the said inlet rockers, both of the said rockers being operated in counter directions by pushrods passing to either side of the said rocker shaft.

Preferably, in both of the said rockers, the ratio of the pushrod to pivot length to the pivot to valve length is

1:1.5. The bosses of the said rockers are provided with suitable wear-resistant bushings and are rotationally supported on the said rocker shaft. Rocker shaft 79 is preferably made hollow for lightness and is carried on suitable pillars (depicted as 231 in Figure 17) made integral with the said cylinder head casting. Wrapped around the adjacent bosses of the said inlet and exhaust rockers for each of the said cylinders are rocker tensioning springs (depicted as 238 in Figure 17) the ends of which catch under the pivot to valve part of each rocker, tensioning it to the valve closed position. Said inlet and exhaust valve heads are accomodated in more or less hemispherical recesses forming part of the combustion chamber. ith further reference to Figures 18 and 24, one port of the pair of said inlet ports for each of the said cylinders is provided with an auxiliary inlet port 80 which enters it part way down its length and which communicates by way of short gallery 81 to auxiliary inlet manifold 82, said auxiliary inlet manifold being supplied with fuel-air mixture by duct 83 connecting it to inlet 85 on carburettor mounting face 84. One each of the pair of said inlet ports for each of the said cylinders is supplied with fuel-air mixture through inlet manifolding (the runners of which are depicted as 253 to 258 in Figure 18) made integral with the rocker cover. Said inlet manifolding comprises two separate groups of three runners which join to form common inlets 86 and 87 on said carburettor mounting face.

Spark plugs 88 are carried in recesses 89 adjacent each of the said combustion chambers and entering said combustion chambers between said inlet valves.

With reference to Figure 2, hollow quill shaft 33 is made coaxial with camshaft 27 with sufficient clearance between the said shafts to permit independant torsional movement. Pressed onto splines at one end of the said quill shaft against shoulder 90 is flywheel drive boss 91. One end of the said camshaft abuts the said flywheel drive boss, the other being provided with castellations 94 which engage complementary castellations 94a on an inward axial extension of the boss of camshaft drive gear 92 and by which said camshaft is driven. Said camshaft drive gear is carried on splines on the said quill shaft and is secured in place, imprisoning the said camshaft, by nut 93 screwed onto a thread on the said quill shaft. The part of the said quill shaft extending axially beyond the said nut is supported in tapered roller bearing 96 housed in end cover 95. The inward axial extension of the said camshaft drive gear and the end of the said camshaft are carried in tapered roller bearing 97 housed in engine crankcase casting 8. Said flywheel drive boss 91 is carried in a tapered roller bearing 110 which is housed in flywheel drive boss housing 131. Fixed to the outer face of the said flywheel drive boss and collinear with the axis of the said quill shaft is flywheel 98, said flywheel being spigoted to the end of the said quill shaft and the said flywheel drive boss by hollow spigot shaft 99. The bolts (not shown) by means of which the said flywheel is fixed to the said flywheel drive boss pass first through flange 100 of the said hollow spigot shaft. The described arrangement of the quill shaft 33 provides a flexural buffer for the power train from the engine and the resultant provision of a power takeoff at half crankshaft speed simplifies the transmission requirements for the engine. Additionally, the torsional twist of the said quill shaft may be measured by electronic means and integrated with engine R.P.M. to provide an instantaneous indication of engine power.

The flywheel 98 comprises boss part 101, disc 102 and peripheral web 103, said elements acting to create a broad, shallow cylinder more or less hollow on the side adjacent the said crankcase casting 8. Contained within the hollow area of the said flywheel is body part 104 of an oil to air heat exchanger. Said heat exchanger body part is captured at its outer periphery between the forward face of the said flywheel peripheral web and clamping ring 105 fixed to it by suitable fastenings (not shown) and at its inner periphery between the said flywheel boss part and the said flywheel mounting boss, sealed at both locations by suitable 'O' rings 127 and 128. Said heat exchanger body part contacts the inner face of the said flywheel disc part 102 such that the space between the two said parts is divided into inner lubricant space 106 and outer lubricant space 107. Passing from the said inner lubricant space to the said outer lubricant space is a plurality of thin flat hollow vanes 108, and connecting the said outer lubricant space to drillings 121 in the said flywheel drive boss are return ducts 109. The provision of a power take off stub shaft 111 increases the utility of the invention. The power takeoff stub shaft 111 is driven by drive gear 112 via a gear train from the said crankshaft and is supported by tapered roller bearings 114 and 115, respectively housed in a downward extension of crankcase casting 8 and end cover 95 and sealed to the exterior of said end cover by seal 116. The body of the said power takeoff drive gear is developed axially to accomodate centrifugal lubricant pump 113 or any other suitable pump. Oil from the oil pan (not shown) passes to the inlet 117 of the said pump 113 through pickup duct 60, is discharged into volute 118 and thence via transfer duct 119, said hollow quill shaft, said hollow spigot shaft and drillings in said flywheel boss part, passes to said inner lubricant space. From the said inner lubricant space 106, said lubricant passes via the said thin, flat hollow vanes to the said outer lubricant space

107, rotation of the said flywheel causing a continuous flow of cooling air to pass over said vanes conducting away heat from the said lubricant. From the said outer lubricant space, said lubricant passes via return ducts 109, drillings in flywheel hub part 121 and flywheel drive boss 122 to annular space 123 in crankcase 8 from whence it passes via ascending duct 124 to the cylinder head casting 10. Egress of lubricant from annular space 123 is minimised by the provision of minimal clearance between the outer face of the said flywheel drive boss and machined bores 125 and 126.

Leakage of lubricant from around the said flywheel drive boss is prevented by piston ring 129 located in groove 130 in said flywheel drive boss and bearing on a machined bore in said flywheel drive boss housing, and lip seal 132

» bearing against the outer surface of the said flywheel drive boss. Lubricant transfer duct 119 is provided with tapping 133 to a boss on end cover 95, said tapping normally being closed by screwed plug 134. Provision may be made to bypass the said flywheel heat exchanger and conduct lubricant from the said tapping to a remote heat exhanger and thence back to the engine to annular space 123 via a drilling in a boss

(depicted as 228 in Figure 13) in flywheel drive boss housing 131. The flywheel heat exchanger provides a compact means of regulating the temperature of coolant entering the engine, the coolant effect of the said heat exchanger relating to engine R.P.M.

With reference to Figures 3 and 5, the end part of the said crankshaft 2 is extended axially beyond its final crank web 4 to form stub shaft 160 which extends through crankcase casting 8 into end cover 95. Carried upon splines on the said stub shaft is a bearing support collar 135 which incorporates crankshaft driven gear 223 and is retained on said stub shaft by flange 137 of bearing retaining bolt 138 which is screwed into threaded bore 162 in the end of the said stub shaft 160. Carried upon the bearing support collar 135 are two tapered roller bearings, the inner races of which are separated by spacer 139 and also retained by the said bearing retaining bolt flange 137. The outer races

136 of the tapered roller. bearings are housed in a machined bore 140 in end cover 95, the outermost race being retained by bearing retainer 142 secured to the outer periphery of end cover 95 by suitable fastenings (not shown). The said bearing retaining bolt, stub shaft, bearing support collar and spacer are provided with suitable oil ways to permit a flow of lubricant to said tapered roller bearings from said crankshaft hollow part 5. The bearing retaining bolt head may be extended axially to form shaft 143 upon a cylindrical part of which is mounted starter gear 144 turning upon two narrow needle bearing races 161. The boss of said starter gear is extended axially to form collar 145, the outer face of which is made to coact with rollers or sprags 146 of a one-way drive assembly 147. Said one-way drive assembly is fixed to a tapered part of the said shaft together with alternator rotor 148 and secured by nut 149 screwed onto threaded end 150 of the said shaft.

A secondary cover 151 may be fixed to a face of end cover 95 covering said starter gear, one-way drive assembly and alternator rotor. Said secondary cover 151 may be provided with a shallow cylindrical compartment 152 on its outer face, the axis of which is made collinear with the extended axis of rotation of the said crankshaft. Screwed into threaded bore 156 on the end of shaft 143 is extension shaft 154 which passes through said end cover through sealing means 155 into said cylindrical compartment to drive rotor 153. Said rotor generates pulses for ignition purposes as it passes Hall effect devices (not shown) housed in said cylindrical compartment. Said cylindrical compartment may be closed by a simple cover (not shown) . Starter gear 144 meshes with reduction gear assembly 157 turning on shaft 158. Starter motor pinion (not shown) meshes with said reduction gear assembly, driving the shaft 143 and thus the said crankshaft through the said one-way drive assembly.

Figure 4 of the drawings illustrates the end of the crankshaft opposite to that shown in Figure 3. The end part of the crankshaft illustrated is extended axially beyond its final crank web 4 to form stub shaft 163 which extends through crankcase casting 8. Said stub shaft carries the inner races of two tapered roller bearings 164, which are separated by spacer 169 and captured between shoulder 165 at the root of the said stub shaft and flanged head 166 of bearing retaining bolt 167 screwed into threaded bore 168 in the end of the said stub shaft. The head of bolt 167 is extended to create an oil pump drive shaft 170, two splines 171 on the end of which engage complementary dogs 172 on the inner rotor 173 of a rotor type oil pump. Said inner oil pump rotor 173 and outer oil pump rotor 174 operate in bore 175 of oil pump casting 176. In operation, lubricant passes from an oil gallery (not shown) in the said cylinder head casting, down an annular space between a cylinder head bolt and its bore 177, through transfer duct 178 to intake port 179 of the said oil pump. Oil is forced from the said pump through delivery port 180, through a drilling 181 in bolt 167 to hollow part 136 of the said crankshaft. Said bearing retaining bolt, crankshaft stub shaft and bearing spacer are provided with suitable oil ways to permit a flow of lubricant to the said tapered roller bearings from drilling 181 in bearing retaining bolt 167. The outer races of the said tapered roller bearings are made combined into a single unit 182 which is housed in a bore 183 in crankcase casting 8 in a light sliding fit, which arrangement permits axial movement to accomodate thermal expansion of engine components. Said oil pump body is located to bore 183 in crankcase casting 8 by spigot 185 on said oil pump body and sealed by ' 0 ' ring 184. - 21 -

With reference to Figures 6 and 7, the two central crankshaft main bearing shafts 31 are made plain and cylindrical, to be supported in steel-backed shell bearings which are well-known in the art. Said shell bearings are accomodated in two full-circular cast metal bearing housings

186 which comprise two semi-circular elements and which are in turn accomodated in machined bores 187 in the crank tunnel in crankcase casting 8. Said semi-circular bearing housing elements are assembled onto the said crankshaft with said shell bearings in place and secured together by bolts

(not shown) passed through bores 188 and screwed into threaded bores 189 thereby crushing the said shell bearings.

With said double tapered roller bearings installed at each end in the manner aforesaid, the said crankshaft is then inserted into bore 218 in the end of said crankcase as depicted in Figure 10 until said end tapered roller bearings and said centre main bearing housings enter their machined bores in the said crank tunnel. The leading edge of each of the said bearing housings is provided with a suitable chamfer 190 to facilitate the entry of each into its said machined bore. Said crankshaft is then imprisoned within the said crank tunnel by the installation of end cover 95 and bearing retainer 142 depicted in Figure 3 and oil pump body 176 depicted in Figure 4. During assembly of the said cylinder head, the four centre cylinder head bolts (not shown) pass down through bores in the said crankcase casting

(not shown), through bores 191 in the said upper semi-circular bearing housing element and are screwed into threaded bores 192 in the said lower semi-circular bearing housing element positively locating the said full-circular main bearing housings within the said crank tunnel. In an alternative embodiment, to facilitate the assembly of the said full-circular main bearing housings into the said machined bores in the said crank tunnel, the said bearing housings may be made such that the first to enter the said crankcase during assembly is smaller in diameter than that following and both are made slightly tapered such that the diameter of the first part of each to enter its crank tunnel machined bore is made smaller. Similarly the machined bores in the said crank tunnel would also be made with a complementary taper. Said main bearing housing elements are preferably made from a material having a greater coefficient of thermal expansion than the material from which the said crankcase casting is made. In such an arrangement, cold clearances provided between said main bearing housings and the said machined bores in which they are accomodated may be taken up by thermal expansion at engine operating temperature. Said main bearing housing elements are provided with apertures 193 to permit pressure equalisation between adjacent parts of the said crankcase. Said crank tunnel is made more or less cylindrical with localised circumferential expansions 194 adjacent cylinder centre lines to accomodate the lateral throw of the engine connecting rod big end bosses. Lubricant is provided to the said crankshaft main shell bearings from hollow part 5 in main bearing shaft 31 via suitable drillings (not shown). Said arrangement of crankcase, crankshaft and bearings permits the rapid removal and replacement of the said crankshaft. More specifically, the arrangement facilitates the installation of the said crankshaft in the said crankcase by robotic means.

With reference to Figures 8 and 9, balance shaft 28 is accomodated in balance shaft gallery 195 in the said lateral extension 25 of crankcase casting 8. Said balance shaft is comprised of a tubular member 196, drive boss 197 and end boss 198. Said drive boss is made hollow with a narrow bore 204 which passes through it and is extended axially to form drive shaft 199 which is carried in ball bearing 200 housed in a machined recess in the said crankcase casting. Fixed to the said drive shaft is balance shaft drive gear 201 which is driven at crankshaft speed via a gear train from the said crankshaft. The outer part of the said drive shaft is carried in ball bearing 202 which is housed in a machined recess in end cover 95 which totally encloses the said drive shaft, drive gear and bearing 202. Communicating with the outer end of bore 204 of the said drive shaft is a breather duct 203 which emerges from a boss in said end cover through threaded bore 205 into which suitable engine breather means (not shown) is screwed. End boss 198 is extended axially to provided end shaft 206 which is carried in ball bearing 207 housing in machined recess

209 in the said crankcase casting and secured to the said shaft by circlip 208. Conveniently, three balance weights

210 of appropriate mass and phasing are fixed to the inside or tubular member 196 and serve to damp out lateral engine vibrations of small amplitude. A plurality of small holes (not shown) is provided in tubular member 196 through which pressure generated in the said crankcase is vented via bore 204 and breather duct 203. The rotation of the said shaft serves to centrifugally separate entrained oil droplets from the said venting flow.

With reference to Figure 10, outer cylinder head bolts 212 and 213 at the gear train end of the engine are secured in two different ways. Bolt 212 is made shorter than bolt 213 and passes down a bore (not shown) in crankcase casting 8 and is screwed into threaded bore 216 in cylindrical steel slug 217 inserted in a light sliding fit into a bore (not shown) in the end of said crankcase casting. Bolt 213 passes down a bore (not shown) in the said crankcase casting and is screwed into a threaded bore 214 in solid inwardly-projecting sector 211 of end cover 95 which is spigoted into bore 218. Said inwardly-projecting sector is also depicted in Figure 3. With reference to Figure 14, the two cylinder head bolts 219 at the flywheel end of the engine are made equal in length and pass through bores (not shown) in the said crankcase casting either side of bore 183 and beneath oil pump mounting flange 221 and emerge through holes (depicted as 227 in Figure 13) in machined face 222. Threaded ends of said bolts are secured with nuts 220.

With reference to Figures 11 and 12, crankshaft - - driven gear 223 mounted upon bearing support collar 135 meshes with the larger pitch circle band 225 of double gear

226 with which larger pitch circle band also meshes power takeoff stub shaft drive gear 112. Meshing with the smaller pitch circle band 224 of said double gear is camshaft drive gear 92 which meshes with balance shaft drive gear 201.

Said double gear turns on a roller bearing on a shaft (not shown) pressed into a bore in the end of said crankcase casting and spigoting into a bore in the said end cover.

Preferably, all of the said gears are made with helically cut teeth.

With reference to Figure 13, depicted are circumferential expansions 194 of said crankcase to accomodate throw of connecting rod big ends; crank tunnel lubricant drainage boxes 69, limber holes 70 and transfer pipes 71; connecting rod big end access slots 19; oil pan mounting face 29; lubricant drainage apertures 61; access hole 230 and mounting pads 229 for camshaft bearing support block (not shown); cylinder head bolt holes 227; and flywheel drive boss housing 131 and boss 228. Boss 228 is adapted for tapping to provide an alternative return path to said engine for a flow of lubricant from a remote heat exchanger.

With reference to Figure 17, rocker shaft 79 is supported on rocker shaft support pillars 231 made integral with cylinder head casting 10 and secured by suitable fasteners (not shown). The single exhaust valve for each cylinder (depicted as 57 in Figure 1) is operated by single rocker arm 78 made integral with bushed boss 233 rotationally supported on said rocker shaft. The said two inlet valves for each cylinder (depicted as 58 in Figure 1) are operated in unison by bifurcated rocker arm 77 made integral with bushed boss 235 rotationally supported upon the said rocker shaft. Around the bushed bosses of adjacent rocker arms is wound rocker tensioning spring, the ends of which are hooked under shallow housings 236 and 237 formed on the said exhaust and inlet rocker arms respectively. Said spring acts to tension the said adjacent rocker arms and their actuating valve train components towards the valve closed position, permitting the use of lighter valve springs with a concomitant reduction in valve seat pressure. Said valve springs (not shown) are seated upon pads 239 and 240 machined in the upper face of the said cylinder head. The cylinder head is secured to the cylinder block by nuts (not shown) on bolts (not shown) passing down through cylinder head bolt bores 241 and secured in the manner aforesaid. The said rocker arms are operated by pushrods (not shown) which pass up through the said cylinder head casting through light metal tubes 242 and 24?. Said rocker shaft is made hollow, said hollow part being supplied with a flow of lubricant through the said rocker shaft support pillars from the said coolant jacketing within the cylinder head. Drillings are provided in the said rocker shaft to convey lubricant from the said hollow part to the said bushed boss of each of the said rocker arms. Inlet ports 47 and 245 are brought out to the top face of the said cylinder head casting. Between the openings of the said inlet ports is situated auxiliary inlet port 80 which opens into inlet port 47 part way down that inlet port's length. Said auxiliary inlet port is adapted to receive a supply of vaporised fuel-air mixture during idle and low power operation.

With reference to Figure 18, rocker cover casting 260 is made integral with inlet manifold runners 253 to 258, which runners are made in groups of three, each group serving one inlet port for each of the said cylinders. Said inlet manifold runners are made with a more or less square internal cross-sectional shape, excepting that runners 253 and 258 are made with a more or less rectangular cross-sectional shape with the greater dimension vertical and runner 255 is somewhat flattened to a more or less rectangular internal cross-sectional shape where it passes over the top of runners 256 and 257 and runner 256 is similarly flattened where it passes under runners 254 and 255. Said inlet manifold runners rise steeply from inlet ports 47 and 245, each group of three runners joining to form two single inlets 86 and 87 in carburettor mounting flange 84. Auxiliary inlet manifold 82 is made integral with the said rocker cover casting in a postion adjacent the said inlet ports in said cylinder head and connected to opening 85 on said carburettor mounting flange by duct 83. Said auxiliary inlet manifold is connected to the lower face of the said inlet manifold casting by drillings 81 which register with auxiliary inlet ports 80 in the upper face of the said cylinder head. Said rocker cover casting is secured to the said cylinder head by bolts (not shown) passing down through bores 248 and screwed into threaded bores in the said cylinder head rocker shaft support pillars. Said inlet manifold runners are made in the arrangement depicted to pass around the said rocker cover securing bolts. Where the said engine is operated on fuels with a high latent heat of vaporation such as ehtanol, the said rocker cover casting is attached to the said cylinder head in a metal to metal fit and the outflow of coolant from the said cylinder head coolant jacketing is permitted to play over and heat the said inlet manifold runners. Where the said engine is operated on dry gas fuels or on fuels with a relatively low latent heat of vaporation, the said inlet manifold casting is separated from the said cylinder head by a suitable heat barrier and the said inlet manifold runners are shielded from the said outflow of coolant from the said cylinder head coolant jacketing by a suitable insulating covering or a deflection shield. A suitable deflector is provided at the junction of duct 83 with auxiliary inlet manifold 82 to ensure that the centre cylinder auxiliary inlet port does not receive an excessive supply of fuel-air mixture.

With reference to Figure 24, in an alternative embodiment, inlet manifold runner 257 to the engine centre cylinder is provided with butterfly valve 264 by means of which said runner can be shut off from its normal means of carburetion. Inserted into duct 83 from the said carburettor mounting face opening (depicted as 85 in Figure 18) is barrel valve 262 which comprises a body part and a rotatable cylindrical valving element contained therein, said valving element being provided with ports arranged in a -. T shape. In operation, where the said engine is idled for a nominal period (say thirty seconds), a timer operates a solenoid or vacuum actuator or the like (not shown) t o simultaneously rotate the shaft of the said butterfly valve 264 and the valving element of the said barrel valve 262 by 90 degrees, cutting off the flow of vaporised fuel-air 0 mixture to auxiliary inlet manifold 82 and permitting a flow of the said mixture through a smaller duct 263 entering inlet manifold runner 245 below the said butterfly valve 264 which has cut off the said inlet manifold runner frnm its normal means of carburetion. The engine will idle 5 satisfactorily on one cylinder for extended periods with greatly reduced fuel consumption and exhaust emissions. Through a controlling switch (not shown), a small displacement of the engine throttle control causes the engine to revert instantaneously to a three cylinder idle 0 condition.

With reference to Figure 19, carburettor mounting block 265 is provided with butterfly valve 266, diversion port 268 and return port 269 which registers with opening 85 on carburettor mounting face 84 which communicates with 5 auxiliary inlet manifold (depicted as 82 in Figure 18) through duct 83. Carburettor 270 is provided with butterlfy valve 267. Cylinder head casting 10 is made with threaded bores at the outer opening of each exhaust port into which exhaust stubs 271 are screwed. Exhaust pipes 276 are 0 captured in said exhaust stubs, the exterior surface of the centre one of which is provided with a deep spiral groove 272. Pressed over the external surface of the said exhaust stub is collar 275 which closes the said spiral groove to create a spiral duct and which is provided with ports 5 registering with the beginning and end of the said spiral duct. Tube 273 connects diversion port 268 to the port at the outer and smaller diameter end of the said spiral duct and tube 274 connects the port at the inner and larger diameter end of the said spiral duct to return port 269. In operation, at idle or low engine power, with butterfly valve 266 closed and butterfly valve 267 slightly or partly opened, atmospheric pressure cases a flow of fuel droplets and air to pass through diversion port 268 and tube 273 to the said spiral duct where the air is heated and the entrained fuel droplets are fully evaporated. From the said spiral duct, the vaporised fuel-air mixure passes through tube 274, return port 269 and duct 83 to the said auxiliary inlet manifold 82. Provision is made to insulate the external surfaces of collar 275 and tubes 273, 274 where the said engine is operated in cold climates. The said arrangement permits idling of the engine with lower fuel flows and with reduced emissions. Further, it provides enhanced driveability in the form of a smoother off-idle transition and a more stable torque generation at low R.P.M.

With reference to Figures 20, 21 and 22, cylinder head casting 10 is made with threaded bores 281 at the outer opening of each exhaust port 54 into which exhaust stubs 271 are screwed. Exhaust pipes 276 are captured in said exhaust stubs, their outer ends joining together at fabricated or cast collector 279, the securing of the said collector to the engine preventing the escape of the said exhaust pipes from the said stubs. The downstream end of the said collector 279 is adapted to accept one or more exhaust pipes 280 or may be formed into a mounting flange for a turbo-charger. Where said collector is not secured in the said manner to the engine, attachment lugs 277 may be provided on the end of each of the individual cylinder exhaust pipes, which attachment lugs index with and are bolted to complementary lugs 278 provided on the said stubs. The said exhaust manifold arrangement provides added utility in the form of ease of adaption of the said engine to a wide variety of installation situations.

With reference to Figure 23, there is illustrated an arrangement for directing cooling air flow over the heat exchanger flywheel 98, the cooling fluid passages (shown in Figure 2) having been at least partially deleted for the sake of clarity. The heat exchanger arrangement formed by flywheel 98 comprises a body part 104 which supports a plurality of thin flat hollow vanes 108 through which lubricant is circulated for cooling purposes (as shown and discussed in relation to Figure 2) . The hollow face of the said flywheel is covered by annular cowlings 289 and 290, which cowlings act to form air inlet plenum 284 and air delivery plenum 287. Said annular cowlings are made to extend over the machined outer face of clamping ring 105 with a small clearance to minimise the escape of cooling air. The radial face of cowling 290 is made with a small clearance from the outer edges of vanes 108. The supply of cooling air to inlet plenum 284 through inlet duct 282 is regulated by butterfly valve 283. Said butterfly valve is operated by thermostatic control means (not shown) located in the said balance shaft gallery which senses the temperature of drainback lubricant into the said crank tunnel from the cylinder area. Cooling air from the said inlet plenum flows through annular opening 286, is accelerated by rotating vanes 108 and is pressurised into delivery plenum 287 and delivery duct 285. The flow of the said pressurised cooling air is controlled by dump valve 286a and secondary cooling air valve 287a which may be arranged to operate in unison. Said dump and secondary cooling air valves are operated by thermostatic control means sensing the temperature of coolant stored in oil pan 30. In operation, coolant is stored at operating temperature in the said oil pan and is cooled as required in the said flywheel heat exchanger to maintain optimum combustion chamber temperatures. The temperature drop across the said flywheel heat exchanger is regulated by butterfly valve 283 controlling the flow of cooling air. When the temperature of the coolant stored in the said oil pan is below that desired, said secondary cooling air valve is closed and said dump valve is open, spilling the flow of said cooling air. When the temperature of coolant stored in the said oil pan rises above that desired, said dump valve is closed and said secondary cooling air valve is opened, admitting the flow of said cooling air to manifold 288 from whence it flows to heat exchanger cores 72.

With reference to Figure 16, cylinder head casting 10 is provided with a process or web 44 developed downwardly from its lower deck 304, said process passing around the perimeter of the said casting and also passing immediately around and between the lower parts of the bores 307 in which the upper parts of the said cylinder liners are accomodated. The upper parts of the said cylinder liners (not shown) are accomodated in bores 307 in a light sliding fit with their upper edges bearing against machined faces 11 at the top of each of the said bores, no gasket or other sealing agent being provided. Apertures 49 are provided through the said cylinder head lower deck to permit coolant to pass from the jacketing on the cooler side of the said cylinder head to the space depicted as 305 in Figure 15. Coolant passing up the ascending duct depicted as 124 in Figure 2 enters passage 306 in the said cylinder head and passes to a gallery 291 extending across the full width of the said cylinder head. Volume tubes 52 and 53 pass along the full length of the said cooler and hotter side coolant jackets respectively, each being provided with drillings to direct coolant at locations requiring cooling. Said volume tubes pass just above the lower deck of the said cylinder head casting and just below two transverse partitions depicted as 50 and 51 in Figs. 1, la dividing the approximate upper two thirds of the said cooler and hotter side coolant jackets into three discrete zones adjacent the said cylinder bores. The said cooler side coolant jacket is divided from the said hotter side coolant jacket by a longitudinal web created by joining all of the said inlet ports throughout their vertical length and extending longitudinally to meet the walls at each end of the said cylinder head casting and vertically to meet the upper and lower decks of the said cylinder head casting. Apertures in the lower deck of the said cylinder head casting are closed by welch plugs 56.

Light metal push rod tubes 242 and 243 pass through the depth of the said cylinder head casting and are pressed into its upper and lower decks. Some of said coolant entering passage 306 passes down^' the annular space between cylinder head bolt bore 177 and the cylinder head bolt accomodated therein, exiting via duct shown as 178 in Figure 5 to pass to an oil pump driven from the end of the said crankshaft.

Coolant entering the hotter side coolant jacket exits said jacket into the said rocker compartment through suitable drillings in the upper deck of the said cylinder head casting, said exiting coolant, in the case of some liquid-fuelled engines, being permitted to flow over and heat the inlet manifold runners contained in the said rocker compartment and depicted as 253 to 258.

With additional reference to Figure 25, coolant entering the said cooler side coolant jacket 315 passes through lateral drillings 316 to the annular space 317 between hollow cylinder head bolts 318 and the bores 308 in which they are accomodated. A small groove 319 is provided in each face on the upper deck of the said cylinder head casting upon which washers 320 beneath the cylinder head bolt nuts 321 bear, said grooves being provided to permit the venting of air trapped in annular space 317. Part of the coolant flow entering the said annular spaces between cylinder head bolt bores 308 and bolts 318 accomodated within them from lateral drillings 316, passes down the said annular spaces into the said crankcase casting, through a plurality of drillings 322 into the internal passage 323 in each of the said bolts, and out the top of each of the said bolts through a simple thermostatic valve. The balance of the said coolant flow passes across saw cuts depicted as 295 to 299 in the said cylinder head casting and across complementary saw cuts in the said crankcase casting depicted as 310 to 314 in Figure 15, into the annular spaces between cylinder head bolt bores 177 and 309 and the bolts accomodated within them, exiting in the said manner through the said cylinder head bolts and the said thermostatic valves at the top of each. The said thermostatic valves -. comprise a cylindrical body part 324 divided by partition 325 which is provided with a central aperture which may be closed when said coolant is cold by valve 329 carried on rod 328 connected to wax pellet capsule 327 known in the art. When the temperature of cylinder head bolt 318 rises to the

10 appropriate level, the expansion of the said wax pellet capsule extends rod 328, raising valve 329 and opening the said aperture in the said partition and permitting a flow of coolant out through openings 326 in the said body part. The rate of coolant outflow via the said complex exit path from - - the cylinder head cooler side coolant jacket is thus made temperature sensitive and acts to ensure that optimum combustion chamber temperatures are extablished rapidly and maintained during all phases of operation.

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5

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. A reciprocating internal combustion engine comprising a plurality of cylinders, a crankshaft, connecting rods pivoted to said crankshaft and to piston members adapted for reciprocation in said cylinders, said engine being characte ized by a crankcase generally surrounding said crankshaft and lower regions of said cylinders, and a cylinder head generally surrounding upper regions of said cylinders with a dividing face between said crankcase and said cylinder head meeting part way along the longitudinal length of said cylinders, and each of said cylinders being formed by a removable liner member having a cylindrical bore receiving a respective one of said piston members .

2. A reciprocating internal combustion engine according to claim 1 wherein each said liner member abuts against a respective annular ledge formed in said cylinder head.

3. A reciprocating internal combustion engine according to claim 2 wherein resilient means interposed between said liner members and said crankcase urge said liner members against the respective annular ledges formed in said cylinder head.

4. A reciprocating internal combustion engine according to claim 2 or claim 3 wherein contact is established between each said liner member and the associated annular ledge formed in said cylinder head along an annular line.

5. A reciprocating internal combustion engine according to any one of claims 1 to 4 wherein the dividing face between said crankcase and said cylinder head is located below top dead centre position of gudgeon pins connecting said piston members to connecting rods of the engine .

6. A reciprocating internal combustion engine according to any one of claims 1 to 5 wherein narrow lands surround cylinder spaces in both said crankcase and said cylinder head whereby said lands engage one another when said engine is operably assembled.

7. A reciprocating internal combustion engine according to claim 6 wherein a recessed space is provided surrounding the narrow land at said dividing face in at least one of said crankcase or said cylinder head.

8. A reciprocating internal combustion engine according to any one of claims 1 to 7" wherein each said piston member includes a peripheral rounded shoulder facing towards said cylinder head, said surrounded shoulder cooperating with a complementary squish surface within the cylinder head at TDC position of the piston member.

9. A reciprocating internal combustion engine according to any one of claims 1 to 8 wherein the longitudinal axes of said cylinders are arranged in a common plane with a power take off shaft driven by said power transmission means from said crankshaft made parallel to and being laterally offset relative to said crankshaft.

10. A reciprocating internal combustion engine according to claim 9 wherein two sets of said cylinders are provided, the longitudinal axes of the cylinders in each said set being arranged in a common plane whereby a said crankshaft is provided for each said set of cylinders, said power take off shaft being situated between and parallel to both said crankshafts and said power take off shaft being driven by said power transmission means from both said crankshafts.

11. A reciprocating internal combustion engine according to any one of claims 1 to 10 wherein a single fluid is used in the engine both as a lubricant for moving parts in the engine and as a temperature control medium.

12. A reciprocating internal combustion engine according to claim 11 wherein flow of said fluid as a temperature control medium is confined substantially to said cylinder head through separate hot and cold side coolant jacketing and flow circuits, said coolant jacketing being partially subdivided into discrete zones above each cylinder thereby enabling even temperature distribution and better control of combustion chamber temperature.

13. A reciprocating internal combustion engine according to claim 11 or claim 12 wherein storage means is provided for said fluid to receive fluid from said engine after circulation through passage means in said engine, said storage means being divided into at least two compartments with fluid cooling means being associated with at least one larger of the said compartments, means for restricted circulation of fluid from the or each compartment with said fluid cooling means to a smaller compartment without said fluid cooling means, and means for recirculating said fluid from the said compartment without said fluid cooling means to the engine, said storage means further including valve means enabling fluid flowing from said engine to enter said compartment without said fluid cooling means when the temperature of the fluid flowing from said engine is below a predetermined level and to direct said fluid flowing from the engine into a said compartment or compartments with said fluid cooling means when the temperature of the fluid flowing from said engine is above said predetermined level.

14. A reciprocating internal combustion engine according to claim 11 wherein storage means is provided for said fluid to receive fluid from said engine after circulation through passage means in said engine, and recirculation means being provided to direct said fluid from said storage means back to said engine for lubrication and temperature control purposes, temperature sensor means being provided to sense temperature of said fluid directly as the fluid leaves said engine, and heat exchange means provided to control the temperature of the fluid re-entering said engine in response to the temperature of the fluid sensed by said temperature sensor means.

15. A reciprocating internal combustion engine according to claim 14 wherein cooling air is adjustably directed to said heat exchange by a fan forming part of a flywheel of said engine, the flow of said cooling air being controlled in response to the temperature of the fluid sensed by said temperature sensor means.

16. A reciprocating internal combustion engine according to claim 15 wherein said flywheel is made at least partially of hollow construction whereby said fluid is circulated therethrough in heat exchange relation with said cooling air.

17. A reciprocating internal combustion engine according to any one of claims 1 to 16 wherein the or each said crankshaft comprises a plurality of main shaft portions and a plurality of crank pin portions parallel to said main shaft portions but offset laterally therefrom, and said crank pin portions being angularly spaced relative to each other around said main shaft portions, the or each said crankshaft further comprising a plurality of crankshaft webs joining ends of each said crank pin portion to an end of a main shaft portion, the or each crankshaft further including internal passage means extending substantially along the length thereof to receive a temperature control fluid therethrough.

18. A reciprocating internal combustion engine according to claim 17 wherein said crankshaft webs are circular in cross section with portions of said webs opposite said crank pin portions relative to said main shaft portions being solid thereby providing a counter balance effect.

19. A reciprocating internal combustion engine according to claim 17 or 18 wherein pump means is provided driven directly from the end of the crankshaft(s) and adapted to receive and pump lubricanting and temperature control fluid through the or each said crankshaft.

20. A reciprocating internal combustion engine according to any one of claims 1 to 19 wherein said cylinder head includes a plurality of spaces defining upper ends of combustion chambers and bores adapted to receive said liner members, each said combustion chamber having an exhaust port leading therefrom together with an exhaust valve for controlling flow through said exhaust port, and at least two inlet ports for introducing a combustible charge into said combustion chamber, flow through said inlet ports being controlled by inlet valves.

21. A reciprocating internal combustion engine according to claim 20 further including spring means associated with each of said inlet and exhaust valves to bias said valves to a normally closed position.

22. A reciprocating internal combustion engine according to claim 21 wherein the inlet and the exhaust valves for each said combustion chamber are operated by separate rocker arms rotatably supported on a single rocker shaft, the rocker arms for the inlet valves being bifurcated and actuated by push rods from a remote camshaft, and auxiliary spring means acting between said rocker arms on said rocker shaft urging the said rocker arms and their actuating valve train components to a valve closed position.

23. A reciprocating internal combustion engine according to any one of claims 20 to 22 wherein for each said combustion chamber, a first one of the inlet ports is led to a first common inlet manifold runner while the other of the inlet ports of each said combustion chamber is led to a second common inlet manifold runner.

24. A reciprocating internal combustion engine according to any one of claims 1 to 19 wherein said cylinder head includes a plurality of spaces defining upper ends of combustion chambers and bores adapted to receive said liner members, each said combustion chamber having an exhaust port leading therefrom together with an exhaust valve for controlling flow through said exhaust port, and at least one inlet port for introducing a combustible charge into said combustion chamber, flow through said inlet port being controlled by an inlet valve, an auxilliary inlet manifold arranged to introduce a vapourized fuel-air mixture into the or one of said inlet ports, said fuel-air mixture being passed into heat exchange relationship with exhaust gases from said engine prior to introduction into said inlet port or ports.

25. A reciprocating internal combustion engine according to any one of claims 1 to 24 wherein said cylinder head is secured to said crankcase by cylinder head bolts extending deep into said crankcase, at least some of said bolts also being attached to tunnel type main bearing housings for the said crankshaft.

9/2 :va