JPH02212640A - Balancer shaft drive device for internal combustion engine - Google Patents

Abstract

PURPOSE:To facilitate the execution of a regulating work during assembly by a method wherein a positioning recessed part is formed in a direction extending at right angles with the axis of a balancer shaft is formed in the balancer shaft and an insertion hole is bored in an engine body, facing the recessed part, and a rodform member is inserted during assembly of a balancer. CONSTITUTION:In a pair of balancer shafts 21 each having an eccentric weight part, the one of balancer shafts is rotated forward by means of a timing belt 39 and the other balancer shaft 21 is reversed through a pulley 37 for reverse drive, a drive gear 40, and a driven gear 41. The balancer shaft 21 has a recessed part (hole) 92 for positioning formed in a protrusion part 21c formed facing an eccentric weight part and a through-hole 93 formed in a cylinder block 1, facing the recessed part. In assembly of the balancer shaft 21, a rodform member 94, e.g. a plus driver, is inserted for positioning, and the phase thereof is adjusted to that of a crank shaft. This constitution enables facilitation of a regulating work during mounting of the balancer shaft.

Description

Detailed Description of the Invention A1 Object of the Invention (1) Industrial Field of Application The present invention provides a system in which a balancer shaft having an eccentric weight portion is rotatably supported by an engine body parallel to a crankshaft, and the balancer shaft has an eccentric weight portion. A balancer shaft for an internal combustion engine in which an endless transmission band is suspended between a reverse drive driven wheel that is interlocked and connected via a pair of gears to one end protruding from the engine body, and a drive wheel provided on the crankshaft. It relates to a drive device.

(2) Prior Art Conventionally, such devices have been disclosed in, for example, Japanese Unexamined Patent Publication No. 62-20921.
, No. 2, and the like.

(3) Problems to be Solved by the Invention In such a device, the balancer shaft is to be disposed in the engine body with the eccentric weight portion of the balancer shaft having a constant phase with respect to the crankshaft. When assembling it, it is necessary to assemble it while adjusting the above-mentioned phase 8 times uniformly, and it is desirable that the assembling operation involving such adjustment be easy. Further, when the gear is fixed to the balancer shaft while being inserted into the engine body, it is desirable to be able to easily prevent rotation of the balancer shaft. However, the above-mentioned conventional device does not take such consideration.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a balancer shaft drive device for an internal combustion engine that allows easy assembly of the balancer shaft.

B0 Structure of the Invention (1) Means for Solving the Problems According to the first feature of the present invention, the balancer shaft is provided with a positioning recess that extends in a direction perpendicular to the axis thereof, and the engine body is provided with a positioning recess that extends in a direction perpendicular to the axis of the balancer shaft. , an insertion hole corresponding to the positioning recess is opened and bored on the outer surface.

According to the second feature of the present invention, a pair of balancer shafts having eccentric weight portions are rotatably supported in parallel to each other in the engine body, and are connected to one balancer shaft via a pair of gears. An endless transmission band is suspended between a driven wheel for reverse rotation that is interlocked and connected, a driven wheel for forward rotation that is fixed to the other balancer shaft, and a drive wheel that is provided on the crankshaft.

According to the third feature of the present invention, a support member is attached to the engine body, and the protruding portion of the balancer shaft from the engine body is rotatably supported by the support member.

According to the fourth feature of the present invention, a support member is attached to the engine body, and the protruding portions of the pair of balancer shafts from the engine body are rotatably supported by the support member.

According to a fifth feature of the invention, the balancer shaft is provided with two outwardly projecting ridges along one diameter thereof, and a positioning recess is provided in one of the ridges.

According to the sixth feature of the present invention, the positioning recess is provided in the balancer shaft avoiding the portion supported by the bearing hole provided in the engine body and the eccentric weight portion.

Furthermore, according to the seventh feature of the present invention, an insertion hole is formed in the side wall of the engine body on the driving wheel side along the axis of the crankshaft.

(2) Effect According to the configuration of the first feature, when assembling the balancer shaft, the axis of the balancer shaft is The position along the direction and the position around the axis can be determined, the operation of fixing the gear to the balancer shaft is facilitated, and the relative phase of the balancer shaft with respect to the crankshaft can be determined easily.

Further, according to the configuration of the second feature, it is possible to determine the position along the axial direction of one balancer shaft and the position around the axis, which facilitates the operation of fixing the gear to the balancer shaft. The relative phase between the two balancer axes and one of the balancer axes can be easily determined.

According to the configuration of the third feature, the one end support portion of the balancer shaft can be made relatively small in diameter to reduce rotational frictional resistance.

According to the configuration of the fourth feature, it is possible to make the one end support portion of both balancer shafts relatively small in diameter, thereby reducing the rotational frictional resistance of both balancer shafts.

According to the configuration of the fifth feature, it is possible to avoid deterioration in the function of the balance shaft due to the provision of the positioning recess.

According to the configuration of the sixth feature, it is possible to avoid increasing the size of the balancer shaft and to reduce the influence of the positioning recess on the balancer shaft function.

Furthermore, according to the configuration of the seventh feature, since the side wall of the engine body on the one end side along the axis of the crankshaft has high rigidity, it is possible to avoid a decrease in rigidity due to the provision of the insertion hole as much as possible, and the insertion hole has a rod-like shape. The work of inserting the member can be facilitated, the rod-shaped member can be easily confirmed, and forgetting to remove the rod-shaped member can be prevented as much as possible.

(3) Example Hereinafter, an example in which the present invention is applied to a DOHC type in-line four-cylinder internal combustion engine will be explained with reference to the drawings. In the figures and FIG. 4, the engine body E is constructed by connecting a cylinder head 2 to two parts of a cylinder block 1. An oil pan 3 is located at the bottom of the cylinder block 1, and an oil pan 3 is located at the top of the cylinder head 2. The helad covers 4 are respectively combined.

The cylinder block 1 includes an upper cylinder barrel portion 1a and a lower crankcase portion 1b, and is made of aluminum alloy. In the cylinder barrel part 1a,
Four cylinder bores 5 arranged in series are provided, and a piston 6 is slidably fitted into each cylinder bore 5. Also, crank case part 1
b, a plurality of journal bearings 7 are spaced apart along the arrangement direction of each cylinder bore 5, and bearing caps 8 are respectively fixed to the lower surface of each journal bearing 7. The crankshaft 9 is rotatably supported by the journal bearings 7..., and the crank pins 9a of the crankshaft 9 and the pistons 6...
・are connected to each other via a connecting rod 10 . Further, each of the bearing caps 8 . . . is integrally coupled by a bridge member 11.

At one axial end of the crankshaft 9, an oil pump 12 driven by the crankshaft 9 is disposed on the outer side wall 1c of the cylinder block 1. This oil pump 12 has a rotor 14 fixed to the crankshaft 9 within a pump case 13 attached to the side wall outer surface 1c of the cylinder block 1.
An oil strainer 17 is connected to a suction port 15 provided in the pump case 13 via a suction pipe 16. Further, a discharge port 18 provided in the pump case 13 is connected to a lubricating oil passage 19 bored in the cylinder block 1 parallel to the crankshaft 9 . The other axial end of the crankshaft 9 projects slightly from the other end side wall of the cylinder block 1, and a transmission is connected to the other end of the crankshaft 9 via a clutch (not shown).

Referring to FIGS. 5 and 6 together, on the L side of the crankshaft 9, there is a first balancer shaft 21 and a second balancer at a position that is approximately symmetrical with respect to a vertical plane passing through the axis of the crankshaft 9; A shaft 22 is rotatably arranged parallel to the crankshaft 9. These balancer shafts 21 and 22 suppress secondary vibrations of the engine, and are inserted into the cylinder block 1 with one axial end protruding from the side wall outer surface 1c of the cylinder block 1. Both balancers 2122 have eccentric weight portions 21a, 21b; 22a, 22b spaced apart from each other near the other end in the axial direction, and the cylinder block 1 has a first balancer. A pair of bearing holes 23, 2 that support a portion of the shaft 21 near the other end in the axial direction
/l, and a pair of bearing holes 25.26 that support a portion of the second Haranza shaft 22 closer to the other end in the axial direction, and a bearing that supports a portion of the second balun-IJ'' shaft 22 closer to one end in the axial direction. A hole 27 is provided.

One end of the crankshaft 9 projects from the pump case 13 of the oil pump 12, and the projecting end of the crankshaft 9, which is rotationally driven in the direction shown by the arrow in FIG.
The first drive pulley 28 of the wrap transmission system T1 is fixed, and the second drive pulley 29 as a drive shaft of the second wrap transmission system T2 is fixed on the side farther from the cylinder block J than the first drive pulley IJ28. be done.

[No.] Wrap transmission system Tl includes an intake side valve train camshaft 30 rotatably supported on the cylinder head 2 parallel to the crankshaft 9 to drive the intake side valve train, and an exhaust side valve train. The exhaust side valve operating camshaft 31 is rotatably supported on the cylinder head 2 parallel to the crankshaft 9 to drive the engine, and the water pump 32 is attached to the outer surface IC of the side wall of the cylinder block 1. It is a time transmission system, and includes a first drive pulley 28, a camshaft drive driven pulley 33.34 fixed to both camshafts 30.31, and a water pump fixed to the pump shaft 32a of the water pump 32. Drive driven pulley 35 and each pulley 28.33,
34. The first endless transmission band suspended from 35
It is composed of a timing belt 36.

Further, the second winding transmission system T2 is a transmission system for driving the first and second balancer shafts 21 and 22, and is a reverse rotation drive that is interlocked and connected to the second drive pulley 29 and the first balancer shaft 21. Driven boot IJ 37 for reverse drive as a driven wheel
, a forward rotation drive driven pulley 38 as a forward rotation drive driven wheel provided on the second Haranza shaft 22, and each pulley 29,
3.7.38, and a second timing belt 39 as an endless second transmission band.

Referring to FIGS. 7 and 8 together, a gear case 42 that covers a part of the pump case 13 is attached to the pump case 13 at a portion corresponding to the first balancer shaft 21. That is, the gear case 42 is attached to the cylinder block 1 together with the pump case 13 by the port I.43. The reverse rotation drive driven pulley 37 is fixed to the protruding end of the gear case 42 of a rotary shaft 44 that is rotatably supported by the gear case 42 in parallel with the first balancer shaft 21 . In addition, one end of the first Haranza shaft 21 is rotatably supported by the pump case 13 and is connected to the gear case 42.
It is thrust inside. A pump case 13 is attached to the outer side wall 1c of the cylinder block 1 as a supporting member.
A bearing hole 1.3a for rotatably supporting one end of the first Haranza shaft 21 is bored in the bearing hole 1.3a, and the pump case 13 and gear case 4 are connected to each other through the bearing hole 1.3a.
One end of the first balancer shaft 21 is inserted between the two. Thus, between the pump case 13 and the gear case 42, the gear 41 fixed to the end of the first balancer shaft 21 and the gear 4O integrally provided at the inner end of the rotating shaft 44 are meshed with each other. . Therefore, the power from the reverse rotation driven pulley 37 is applied to the first balancer shaft 21 through the mutually meshing gears 4.
0,4]. Zunawachi Ryo Haranza Axis 2
1 and 22 are rotated in opposite directions.

In FIG. 9, the first parallel shaft 21 has a portion supported by the bearing hole 23, 24 of the cylinder block 1, and a position that avoids the eccentric weights 21a, 21b, for example, the crankshaft 9 of the cylinder block 1. A positioning recess 92 extending in a direction perpendicular to the axis of the balancer shaft 21 is provided at a portion corresponding to the side wall of the second drive boob IJ 29 along the axis. The positioning recess 92 is bored at a position offset from the axis of the first balancer shaft 21, and the first balancer shaft 21 has two radially outward holes on one diameter line of the first balancer shaft 21 to maintain balance. A pair of raised parts 2
1. c, 2], d, and one raised portion 21.c, 2], d is provided. c.
A positioning recess 92 is bored as a through hole.

Further, an insertion hole 93 having the same diameter as the positioning recess 92 is formed in the cylinder block 1 at a position corresponding to the positioning recess 92 and opens on the outer surface of the cylinder block 1 . When assembling the first balancer shaft 21, a rod-shaped member 94 such as a driver is inserted into the positioning recess 92 from the insertion hole 93.

Referring also to FIG. 10, a support shaft 45 parallel to the crankshaft 9 is implanted in the cylinder block 1 in the -1- direction of the crankshaft 9. The support shaft 45 has a large-diameter threaded portion 45a on the base end side and a shaft portion 45b having a male thread 45c with a smaller diameter than the large-diameter threaded portion 45a on the distal end side, which forms the flange portion 45.
d, and is implanted in the cylinder block 1 by screwing the large diameter threaded portion 45a so that the flange portion 45d abuts the side wall outer surface 1c.

A first tensioner 46 for adjusting the tension of the first timing belt 36 in the first winding transmission system T1 is supported on the support shaft 45, and on the axially outer side of the first tensioner 46, The second in the second winding transmission system T2
A second tensioner 47 for adjusting the tension of the timing belt 39 is supported.

11 and 12, the first tensioner 46
, a plurality of balls 50 are interposed between an inner ring 48 supported by a shaft portion 45b of a support shaft 45 and an outer ring 49 in sliding contact with the outer surface of the first timing belt 36. A ring-shaped support member 51 press-fitted onto the outer surface of the base end has a pair of protrusions 51. a, 51. b protrudes outward on a diameter line. A support hole 52 is bored in one of the protrusions 51a, and the first tensioner 46 is swingably supported by a shaft 53 that passes through the support hole 52 and is fixed to the shilling block 1. The inner ring 48 has an arc-shaped elongated hole 54 centered on the shaft 53, and the shaft portion 45b of the support shaft 45 is inserted into the elongated hole 54. The other end of the first tension spring 55, whose one end is engaged with the cylinder block 1, is engaged with the other protrusion 51b, and the spring force of the first tension spring 55 causes the outer ring 49 of the first tensioner 46 to First timing belt 36
The first timing heald 36 is pressed from the outside, thereby applying a certain tension to the first timing heald 36.

The second tensioner 47 includes a plurality of balls 57 interposed between an inner ring 56 and an outer ring 58 that is in sliding contact with the second timing hell 1-39. Further, one end of a tension arm 59 which is rotatably supported by a shaft 60 fixed to the cylinder block 1 parallel to the crankshaft 9 is connected to the inner ring 5.
6.

Furthermore, an arcuate long hole 61 centered on the shaft 60 is bored in the center of the inner ring, and the support shaft 45 is inserted into the long hole 61.
The shaft portion /15b of is inserted. Further, a second tension spring 62 is stretched between the other end of the tension arm 59 and the cylinder block j, and the spring force of the second tension spring 62 causes the outer ring 58 to be attached to the second timing belt 39 from the outside. The two timing belts 39 are pressed against each other, thereby applying a certain tension to the second timing belt 39. In this second tensioner 47, the width of the outer ring 58 is the same as that of the first tensioner 4.
The width is set smaller than the width of the outer ring 49 in No. 6.

Thus, the first timing belt 36 in the first winding transmission system T1 connects the slack side between the first driving pulley 28 and the water pump driving driven pulley 35 to the first tensioner 4G.
By being pressed from the outside toward the inside, the gear case 42 is curved deeply inward, and the gear case 42 is disposed in the empty space created by the curve. Moreover, the angle α between the direction of the pressing force of the first timing belt 36 by the first tensioner 146 and the direction of pressing of the second timing belt 39 by the second tensioner 47 is 90 degrees or more, preferably 120 degrees or more, for example 130 degrees. is set to

The first winding transmission system T1 and the second winding transmission system T2 are covered by a side cover 65, and the support shaft 45
The distal end thereof passes through the side cover 65 and projects outward. Moreover, a nut 66 that is screwed onto the male threaded portion 45c at the tip of the support shaft 45 and comes into contact with the inner ring end surface of the second tensioner 47 is rotatably engaged with the side cover 65.
The oak 1-66 can be rotated from outside the side cover 65. By tightening the nut 66, the inner rings 48.degree. 56 of the first and second tensioners 46, 47 are allowed to move relative to each other in a plane perpendicular to the axis of the support shaft 45 and are brought into contact with each other.

A rotary ring 67 is fixed to the crankshaft 9 and protrudes outward from the Zydkach 65, and a third drive pulley 68 of the third winding transmission system T3 is attached to the rotary ring 67 inwardly in the axial direction. It is integrally provided on the side, and the fourth winding transmission system T4
A fourth drive pulley 69 is integrally provided on the axially outer side.

The third winding transmission system T3 is a transmission system that drives the AC generator 70 and air conditioner compressor 71 attached to the cylinder block 1, and is fixed to the third drive pulley 68 and the input shaft of the AC generator 70. A driven booby IJ72 for driving the A and C generators, a driven pulley 73 for driving the compressor fixed to the input shaft of the air conditioner combination l/fusa 71, and each pulley 68, 7.
2, 73 and an endless heald 74 suspended from the shafts 2 and 73. The fourth winding transmission system T4 is a transmission system for driving the power steering hydraulic pump 75 attached to the cylinder head 2, and is fixed to the fourth drive pulley 69 and the input shaft of the hydraulic pump 75. It is composed of a driven pulley 76 for driving a hydraulic pump, and an endless hel 1-77 suspended by both boules 1769 and 76.

Next, to explain the configuration of the lubrication oil supply system, an oil pump 12 is connected to the lubrication oil passage 19 provided in the cylinder block 1.
The lubricating oil supplied from the oil filter 80 is guided to an oil filter 80 attached to the side surface of the cylinder block 1 at a portion corresponding to the journal bearing 7 located between the two inner cylinder bores 5, 5 along the arrangement direction. Furthermore, the cylinder block 1 includes an oil passage 81 that guides the lubricating oil from the oil filter 80 upward toward the valve mechanism side, and an oil passage 82 that guides the lubricating oil downward.
and are drilled.

On the other hand, the bridge member 11 that interconnects the bearing caps 8... has a central oil passage 83 corresponding to the crankshaft 9.
and each balancer shaft 21, 22 on both sides of the central oil passage 83.
Side oil passages 84 and 85 respectively corresponding to the lateral oil passages 84 and 85 are bored parallel to the crankshaft 9.

The bridge member 11 also includes the oil passages 83, 84.8.
A communication oil passage 86 that connects the oil passages 83 to 5 communicates with each other.
The oil passages 83 to 85 are perforated at a longitudinally intermediate portion thereof to be orthogonal to each of the oil passages 83 to 85.

The bridge member 11 and each bearing cap 8...
In order to supply lubricating oil to the supporting portion of the crankshaft 9, oil supply passages 87 are formed, each extending upward and communicating with the central oil passage 83 at its lower end. Also, the bearing hole 23.2 of the balancer shaft 21
4, the bridge member 11, the bearing cap 8, and the cylinder block 1 have a lower end connected to a side oil passage 84.
Oil supply passages 88 and 88 are drilled to communicate with the bearing holes 23 and 24, respectively, and the lower ends of the bridge member 11, the bearing cap 8, and the cylinder block 1 are provided at one end of the crankshaft 9 in the axial direction. An oil supply passage 89 that communicates with the side oil passage 84 extends downwardly and is bored, and the oil supply passage 89 communicates with an oil supply passage 90 that is bored in the pump case 13 .

This oil supply path 90 is connected to the palancer shaft 2 in the pump case 13.
1 bearing part, and also communicates with the rotary shaft 44 bearing part in the gear case 42. Bearing hole 2 of balancer shaft 22
5, 26, and 27, the bridge member 11,
The bearing cap 8 and the cylinder block 1 have a lower end communicating with the side oil passage 85 and an upper end communicating with the bearing hole 25,
26 and 27, respectively, are drilled therein.

Oil passage 82 that guides lubricating oil from oil filter 80 downward
are communicated with the intermediate portion of the oil supply passage 88 at a portion corresponding to the bearing hole 24, and therefore the lubricating oil from the oil filter 80 is transmitted to each oil passage 83, 84, 85 of the bridge member 11 via the oil supply passage 88. will be supplied to

Next, the operation of this embodiment will be described. The rotation of the crankshaft 9 drives both the first to fourth winding transmission systems T1 to T4. As a result, in the first winding transmission system T1, the valve drive camshafts 30 and 31 are driven with a reduction ratio of 1/2 with respect to the crankshaft 9, and the water pump 32 is also driven. In addition, in the second winding transmission system T2, both balancer shafts 2
122 are driven in mutually opposite directions at a speed increasing ratio of 2/1 with respect to the crankshaft 9.

A first tensioner 46 for adjusting the tension of the first timing belt 36 in the first winding transmission system T1;
2nd timing hell I/3 in the 2nd winding transmission system T2
Since the second tensioner 47 for adjusting the tension of the tensioner 9 is supported by a common support shaft 45, the tensioner arrangement can be made into a combination I-. Moreover, in the first winding transmission system T1, the valve train camshaft 30.3 requires a large drive torque.
1 and the water pump 32, a larger driving load acts on the second winding transmission system T2, but the first tensioner 46 is supported by the support shaft 45 with the first tensioner 46 axially inward than the second tensioner 47. As a result, the load applied to the tip side of the support shaft 45 can be minimized.

Also, the angle α formed by the pressing direction by the first and second tensioners 4647 is set to 90 degrees 1-1 - preferably 120 degrees or more.
By setting -, the direction of the load applied to the support shaft 45 can be shifted and the overall load can be kept small, and together with the arrangement of the first and second tensioners/16.47 described above, the support shaft 45 is It is possible to further reduce the load caused by

In addition, the load on the second winding transmission system 1゛2 is transferred to the first winding transmission system T.
1, it is possible to make the width of the outer ring 58 of the second tensioner 47 smaller than the width of the outer ring 49 of the first winding transmission system T1.
The amount of protrusion from the cylinder block 1 can be reduced, contributing to making the entire engine more compact.

By the way, when assembling the first and second balancer shafts 21.22 to the engine body E, the insertion holes 9 of the cylinder block 1 are
3, the rod-shaped member 94 is inserted into the positioning recess 92. By doing so, the axial position of the first balancer shaft 21 and the phase around the axis can be kept constant. Therefore, it becomes easy to adjust the relative phase of the first Haranza shaft 21 with respect to the crankshaft 9 and the relative phase of the second Haranza shaft 22 with respect to the first Haranza shaft 21. Moreover, since the first balancer shaft 21 is in the fixed InoS state, the operation of fixing the gear 41 to the first balancer shaft 21 becomes easy, and overall the Mi of both balancer shafts 21 and 22 is
Easy to attach and operate.

Moreover, since the positioning recess 92 is provided in the first balancer shaft 21 at a position avoiding the portion supported by the bearing holes 23, 24 of the cylinder block 1 and the eccentric weight portions 21 a21, b, the positioning recess 92 By providing the first balancer shaft 92, the size of the first balancer shaft 21 is not increased.
It does not affect the Haranza axis 210 function and has little influence. Furthermore, the insertion hole 93 corresponding to the positioning recess 92 is provided in a portion of the cylinder block 1 that corresponds to the side wall on the second drive pulley 29 side along the axis of the crankshaft 9, so it is arranged in a relatively rigid portion. The insertion hole 9
3, the decrease in rigidity of the cylinder block 1 due to the provision of the first paranza φd? 2
2, the rod-shaped member 940 can be easily inserted and inserted, and since the rod-shaped member 94 can be easily recognized, it is prevented from forgetting to remove it.

Also, a first balancer shaft 21 inserted into the cylinder block 1
However, since it has an eccentric weight part 2] and a21b near the other end, when one end of the first balancer shaft 21 is supported by the cylinder block 1, a large diameter bearing hole is formed in the cylinder block 1. The first hole was drilled with a relatively large diameter.
The journal portion of the balancer shaft 21 must be supported in the bearing hole, but since one end of the first balancer shaft 21 is supported in the bearing hole 13a of the pump case 13, the diameter of the supporting portion is made relatively small. This makes it possible to reduce rotational frictional resistance.

FIG. 13 shows another embodiment of the present invention, in which a pump case 13 mounted on the outer side wall 1c of the cylinder block 1 has a bearing supporting one end of the first balancer 2. A hole 1.3a is provided, and a bearing hole 131) for supporting one end of the second Haranza shaft 22 is provided. In this way, the bearing holes 13a, 13b can be made relatively small in diameter, and the rotational frictional resistance of the first and second balancer shafts 21, 22 can be kept small.

FIG. 14 shows still another embodiment of the present invention, and parts corresponding to each of the above embodiments are given the same reference numerals.

A bottomed positioning recess 92' is bored in the first paranza shaft 21, and the positioning recess 92' is formed in the cylinder block 1.
An insertion hole 93' corresponding to ' is bored. If the positioning recess 92' is a bottomed hole in this way, the positioning recess 92'
2' is on one diameter line of the first balancer shaft 2], the position of the first balancer shaft 21 around the axis can be uniquely determined.

In the following two embodiments, the present invention was applied to a device that drives the first and second balancer shafts 21 and 22 that are parallel to each other. It can also be applied to a drive device in which the power is transmitted to a single balancer shaft via a pair of gears. In that case, a rod-shaped member can be inserted into a positioning recess provided in the balancer shaft through an insertion hole in the engine body. By passing the crankshaft 9
The relative phase of the balancer shaft with respect to the balancer shaft can be easily determined, and the operation of fixing the gear to the balancer shaft becomes easy.

Effects of the C1 Invention As described above, according to the first feature of the present invention, the balancer shaft is provided with a positioning recess extending in a direction perpendicular to the axis thereof, and the engine body is provided with the positioning recess. Since the insertion hole corresponding to the recess is opened and drilled on the outer surface, the axial position and the position around the axis of the balancer shaft can be easily determined when assembling the balancer shaft 44, so that the balancer shaft &: The adjustment operation at the time of tl rotation can be made easy, and the gee X and fixing operation to the balancer shaft can be made easy, making the assembly operation easy as a whole.

According to the second feature of the present invention, a pair of balancer shafts having eccentric weight portions are rotatably supported in parallel to each other in the engine body, and are connected to one balancer shaft via a pair of gears. Since the endless transmission band is suspended between the interlocked and connected driven wheel for reverse rotation, the driven wheel for forward rotation fixed to the other balancer shaft, and the drive wheel provided on the crankshaft,
By fixing one balancer shaft during assembly, the relative phase between both balancer shafts and the relative phase between one balancer shaft and the crankshaft can be easily determined, and the gear can be fixed to one balancer shaft easily. It becomes easier.

According to the third feature of the present invention, a support member is removed from the engine body, and the protruding portion of the balancer shaft from the engine body is rotatably supported by the support member, so that one end of the balancer shaft It is possible to keep the rotational frictional resistance in the bearing portion low.

According to the fourth feature of the present invention, a support member is attached to the engine body, and the protruding portions of both balancer shafts from the engine body are rotatably supported by the support member, so that one end of both balancer shafts is rotatably supported by the support member. It is possible to keep the rotational frictional resistance in the bearing portion low.

According to a fifth feature of the invention, the balancer shaft is provided with both outwardly projecting ridges along one diameter thereof, and a positioning recess is provided in one of the ridges, so that:
The provision of the positioning recess does not affect the balancer shaft function, and the influence can be minimized.

According to the sixth feature of the present invention, the positioning recess is provided on the balancer shaft avoiding the part supported by the bearing hole provided in the engine body and the eccentric weight part, so that the positioning recess functions as a balancer shaft. It is possible to avoid increasing the size of the balancer shaft while reducing the influence on the balancer shaft.

Furthermore, according to the seventh feature of the present invention, the insertion hole is formed in the side wall of the engine body on the drive wheel side along the axis of the crankshaft, so that the decrease in rigidity of the engine body due to the provision of the insertion hole is minimized. Moreover, it is possible to easily insert the rod-shaped member into the insertion hole, and to prevent forgetting to remove the rod-shaped member as much as possible.

[Brief explanation of the drawing]

Figures 1 to 12 show an embodiment of the present invention, in which Figure 1 is a longitudinal section of the side entrance, Figure 2 is a view taken along the line ■-■ in Figure 1, and Figure 3 is a view of Figure 1. 4 is a sectional view taken along the line II-II of FIG. 1 and FIG. 5, FIG. 5 is a sectional view taken along the ■-■ line of FIG. 7 is a sectional view taken along the line ■-■ in Fig. 3, Fig. 8 is a sectional view taken along the line ■-■ in Fig. 3, and Fig. 9 is a sectional view taken along the line IX-IX in Fig. 7. Figure 10 is a sectional view taken along the line X-X in Figure 2, Figure 11 is a plan view of the first tensioner, and Figure 12 is a xm-x line in Figure 11.
13 is a cross-sectional view taken along the n-line, FIG. 13 is a cross-sectional view corresponding to FIG. 7 of another embodiment of the present invention, and FIG. 14 is a cross-sectional view corresponding to FIG. 9 of yet another embodiment of the present invention. 9... Crankshaft, 13... Pump case as a support member, 2122... Balancer shaft, 21a, 21b
, 22a, 22b... eccentric weight part, 21c, 21d...
...Protuberance, 29...Drive pulley as a drive shaft, 3
7... Driven pulley for reverse drive as a driven wheel for reverse drive, 38... Driven pulley for forward drive as a driven wheel for forward drive, 39... Timing heald as a transmission band, 40.41 ... Gear, 92.92' ... Positioning recess, 93 ... Insertion hole, E ... Engine body

Claims (7)

[Claims] (1) A balancer shaft having an eccentric weight part is rotatably supported by the engine body parallel to the crankshaft, and is interlocked and connected to one end of the balancer shaft protruding from the engine body via a pair of gears. In a balancer shaft drive device for an internal combustion engine in which an endless transmission band is suspended between a driven wheel for reverse drive and a drive wheel provided on a crankshaft, the balancer shaft has a positioning recess extending in a direction perpendicular to its axis. 1. A balancer shaft drive device for an internal combustion engine, characterized in that the engine body is provided with an insertion hole corresponding to the positioning recess opened on an outer surface thereof. (2) A pair of balancer shafts having eccentric weight portions are rotatably supported in parallel to each other in the engine body, and a reverse drive shaft is interlocked and connected to one of the balancer shafts via a pair of gears. The internal combustion engine according to item (1), characterized in that an endless transmission band is suspended between the driving wheel, the driven wheel for normal rotation drive fixed to the other balancer shaft, and the driving wheel provided on the crankshaft. Engine balancer shaft drive. (3) Paragraph (1) or (2), characterized in that a support member is attached to the engine body, and the protrusion of the balancer shaft from the engine body is rotatably supported by the support member. balancer shaft drive for internal combustion engines. (4) The internal combustion engine according to item (2), wherein a support member is attached to the engine body, and the protruding portions of the pair of balancer shafts from the engine body are rotatably supported by the support member. Balancer shaft drive device. (5) Clause (1) characterized in that the balancer shaft is provided with two outwardly protruding ridges along one diameter line thereof, and a positioning recess is provided in one of the ridges. ,
A balancer shaft drive device for an internal combustion engine according to item (2), item (3), or item (4). (6) Items (1) and (2), characterized in that the positioning recess is provided on the balancer shaft avoiding the portion supported by the bearing hole provided in the engine body and the eccentric weight portion;
A balancer shaft drive device for an internal combustion engine according to item (3), item (4), or item (5). (7) No. 1 characterized in that an insertion hole is formed in the side wall of the engine body on the driving wheel side along the axis of the crankshaft.
), (2), (3), (4), (5)
Balancer shaft drive device for an internal combustion engine according to item (6) or item (6).