US3815559A - Crankcase valve structure for a two-cycle engine - Google Patents

Crankcase valve structure for a two-cycle engine Download PDF

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Publication number
US3815559A
US3815559A US00281036A US28103672A US3815559A US 3815559 A US3815559 A US 3815559A US 00281036 A US00281036 A US 00281036A US 28103672 A US28103672 A US 28103672A US 3815559 A US3815559 A US 3815559A
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United States
Prior art keywords
reed
valve
crankcase
closure
connecting portion
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00281036A
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English (en)
Inventor
R Anderson
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Brunswick Corp
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Brunswick Corp
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Publication date
Application filed by Brunswick Corp filed Critical Brunswick Corp
Priority to US00281036A priority Critical patent/US3815559A/en
Priority to FR7329742A priority patent/FR2196665A5/fr
Priority to BE134625A priority patent/BE803662A/fr
Application granted granted Critical
Publication of US3815559A publication Critical patent/US3815559A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
    • F01L3/00—Lift-valve, i.e. cut-off apparatus with closure members having at least a component of their opening and closing motion perpendicular to the closing faces; Parts or accessories thereof
    • F01L3/20—Shapes or constructions of valve members, not provided for in preceding subgroups of this group
    • F01L3/205—Reed valves
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
    • F02B75/00—Other engines
    • F02B75/02—Engines characterised by their cycles, e.g. six-stroke
    • F02B2075/022—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle
    • F02B2075/025—Engines characterised by their cycles, e.g. six-stroke having less than six strokes per cycle two

Definitions

  • Each reed has an outer closure portion integrally interconnected to a common mounting strip by an hourglassshaped connecting portion defining a reduced width thickness withinits length and thereby reduces the spring constant and the effects of [inertia as the reed moves.
  • a stop arm is located outwardly slightly in excess of the normal full position.
  • Two-cycle internal combustion engines may, advantageously, be'constructed employing the crankcase as a pressurizing fuel and, mixture transfer source.
  • Such systems are widely employed, for example, in internal two-cycle combustion engines for outboard motors and the like.
  • a reed valve unit interconnects the crankcase chambers to the source of the fuel-air mixture such as the carburetor and is pressure actuated to selectively introduce the fuel-air mixtureinto the crankcase for transfer to the cyiindersrAs the piston unit moves outwardly, a vacuum is created within the corresponding crankcase which causes the reed valve to open and introduce the air-fuel mixture into the'crankcase.
  • valve structure includes a plurality of openings with a corresponding plurality of individual valve reeds overlying the individual openings for simultaneous opening and closing.
  • Each of the individual reeds consist of a flexible thin spring steel member which is secured flatwiseadjacent one end and extends outwardly therefrom in overlaping overlying relationship to a corresponding valve port or hole.
  • the reeds are formed as extremely flat members lying adjacent to and in overlapping closing relationship to the reed block.
  • a reed back-stop member will normally be provided to limit the opening of the reed valve under the pressure of the piston movement.
  • the reed valves have been of a stri pdike configruation with a relatively narrow securement end portion and a laterally increasing dimension in a linear or straight line manner from the secured end to the outermost unsecured or closure end portion for purposes of distributing the stresses evenly throughout the length of the reed, for example, as disclosed in US. Pat. Nos. 2,669,979, 2,706,972 and 3,541,657.
  • the multiple openings establish a relatively large flow area and provide for the rapid and sufficient transfer of fuel into the crankcase to permit maximum filling of the cylinder.
  • a plurality of openings are employed as it is not practical to have a single large reed valve.
  • the reed valve should open and remain open during the complete intake period in order to establish maximum transfer of fuel into the crankcase.
  • Applicant considered use of a relatively thin reed to increase the opening rate and to reduce the tendency to rebound and thereby increase the engine horsepower. Although an increased power output was obtained, Applicant found this resulted in a significant increase in reed failure.
  • the conventional reed made-of suitable spring steel is 0.008 inch thick. Reducing the thickness of the reed to 0.007 inches, resulted in both a very significant increase in horsepower output and in reed failure. It appeared that some form of self-destruction was associated with the vibrating characteristic.
  • the present invention provides an induction type
  • the reed of the present invention is generally of a bulb type configuration including an outer closure portion integrally interconnected to 'a mounting means by a connecting portion which has a reduced thickness within its length and thereby reducesthe spring constant and the effects of inertia as the reed moves. Further, the stop member is located outwardly slightly in excess of the normal position which allows the full open position for amaximum period without creating damaging stresses within the reed member.
  • the reduced connecting neck portion is, in a preferred and particularly novel construction, a generally hourshaped junction having curved sidewalls between the closure portion and the mounting means.
  • this invention produces a valve reed which will provide a characteristic closely approximating that of the 0.007 inch thick reed.
  • the present invention provides a valve which may be constructed of a spring metal of the order of 0.008 inches thickness-.-
  • FIG. 1 is a cross section of a two-cycle alternate firing two cylinder engine with a crankcase induction valve constructed in accordance with the present invention
  • FIG. 2 is a sectional view taken on line 22 of FIG. 1 and showing the valve block incorporating the improved valve reed units constructed inaccordance with the invention;
  • FIG. 3 is an enlarged plan view of a section of a reed shown in FIGS. ,1 and 2 and clearly illustrating the construction of the'present inventionj v
  • FIG. 4 is an enlarged fragmentary vertical section showing the position of a reedvalve moving between an opened and closed position;
  • FIG. 5 is a set of characteristic curves illustrating the operating characteristic of reeds in accordance with this invention and other reed forms.
  • a two-cycle engine suitable for outboard motor units and the like is shown.
  • the engine includes a cylinder block 1 with an interconnected crankcase 2 with a transverse plane passing through the axis of the engine crankshaft.
  • a crankschaft 3 is supported at each end in suitable bearing assemblies 4 and 5 which also serve to close the opposite ends of the openings through which the crankcase shaft passes.
  • the two cylinder engine shown includes a pair of cylinder bores 6 within the cylinder block 1. The cylinder bores 6 open into the crankcase member 2 and are interconnected in a wellknown manner.
  • a pair of similar pistons 7 are slidably located within the cylinderbores 6 and similarly connected to the crankshaft 3 with the crank throws oppositely spaced by 180 with respect to the crankshaft such that the pistons 7 reciprocate in opposite direction for alternate firing with each 180 of crankshaft rotation, in accordance with well-known constructions.
  • the central portion of the crankcase 2 is divided into a pair of individual chambers 8 and9 by an intermediate combination bearing and valve block 10 secured in position between the crankcase member 2 and the engine block 1.
  • the individual crankcase chambers 8 and 9 are thus in alignment with the respective cylinder bores 6.
  • the combined bearing and valve block 10 is provided with a peripheral intake port 11 aligned with a transfer port 12 in the crankcase, generally in accordance with the structure of US. Pat. No.
  • a carburetor 13 or other fuel source is secured in overlying relationship to the transfer port 12 to a fuel mixture from a suitable source into the valve block 10.
  • the intake port 11 extends circumferentially about the valve block 10 which is provided with opposite end face openings or ports 14 for transfer of the fuel mixture into the respective crankcase chambers 8 and 9.
  • Reed valve membersl5 and i6, particularly constructed in accordance with the teaching-of the present invention, are secured to the end faces in overlying relationship to the ports 14 to control the transfer of the fuel mixture alternately to the chambers.
  • Exhaust ports 18 are provided on the opposite wall of the corresponding cylinder bore, with the respective port's correspondingly controlled by the position of the piston 7.
  • the ports 17 and 18 are closed during the compression and firing of the power stroke of the piston 7 and are appropriately opened during the exhaust and charge stroke to permit exhaust of the burnt mixture and the introducing of a new charge.
  • Reed members and 16 are correspondingly constructed of a suitable flexible, thin, stainless steel and reed member 15 is described in detail with corresponding primed numbers employed to identify the correponding elements of reed member 16.
  • the reed member 15 includes an individual leaf spring reed 19 for each of the ports 14 interconnected to a common annular mounting strip 20.
  • the mounting strip 20 is mounted adjacent to the crankshaft 3 by suitable interconnecting mounting screws 21 and each of the leaf spring reeds 19 extend generally radially into overlying relationship to the valve ports.
  • each of the reeds 19 includes an outer circular closure portion 22 which is spaced from the mounting strip 20 and is integrally connected thereto by a significantly reduced neck or connecting portion 23 extending therebetween.
  • the outer closure portion 22 is generally a cylindrical or circular member which will completely cover and similarly overlap theouter edges of each round port 14.
  • the connecting portions 23 are generally integral hourglass shaped with correspondingly curved circular edges 23a defining a similar connection to closure portion 23 and the strip 20.
  • This reed member is conveniently formed by a stamping process with the neck portion 23 formed by oppositely disposed circular cut out portions with a significantly smaller radius than the closure portion to define a relatively small similar interconnection to the mounting strip.
  • the reed member 15 is formed of the usual leaf spring material which has been widely employed in reed type valves.
  • a multiple armed reed stop 24 issecured in overlapping relationship to the reed unit 15 and includes a plurality of arms 25 which extend outwardly with each individual arm 25 overlying and aligned with a reed '19.
  • Each of the arms 25 is similarly bent or curved outwardly along a predetermined curvature.
  • the stop arms 25 are preferably located to be spaced slightly outwardly of the normal maximum movement of the associated reed 19, as shown in full line illustration at 26 in FIG. 4.
  • the stop arms 25 are located within the elastic limits of the reeds and pre- 'vent extraordinary or exceptional outward deflection without creating interengagement with the normal reed movement.
  • stop arms 25 can advantageously be provided with a resilient cover 27 such that any engagement is damped 'as'a result of the resiliency of the cover.
  • The'valve block may be similarly coveredto dampen the stress as the reeds close.
  • FIG. 5 is a set of characteristic curves showing the horsepower on the vertical axis versus the speed of an engine in revolutions per minute on the horizontal axis for various reeds.
  • the curves were obtained from a production type engine employed in the Merc I400 manufactured and sold by the Marine Division of Brunswick Corporation.
  • Curve 28 is for a conventional 0.008 thickness reed. Reducing the thickness of the reed to 0.007 inches results in the movement of the curve as at 30. The curve closely follows the 0.008 thickness reed curve up to 4,500RPM. Thereafter, the
  • the present invention thus provides a readily constructed reed valve Construction which will produce highly satisfactory and improved operating characteristics in a simple and inexpensive manner.
  • a crankcase induction valve for a two-cycle engine employing a valve block means adapted to be mounted within an engine crankcase and having an induction passageway means connected to a series of port means in a flat face of the block means, and wherein a' series of flexible reeds are secured against the face of the block means and extend circumferentially into a normally seated position over said port means to close the latter, said reeds having an outer'closure portion essentially corresponding to the opening of the ports and located in overlying covering relation to saidports and connected to an inner securement portion by a connecting portion, said connecting portion including a reduced width substantially less than the width of said closure portion and said securement portion and located intermediate the closure and securement portions.
  • crankcase valve of claim 1 wherein said plurality of valve reeds are connected in common to an inner mounting strip and formed of a uniform thickness and said outer port closure portions being generally circular disc-like members disposed in circumferentially spaced relation and said connecting portion being generally hourglass shaped with curved edges extending between the closure portion and the strip.
  • crankcase valve apparatus of claim 1 wherein said series of flexible reeds are secured to a common mounting strip, each of said connecting portion includes corresponding concave edges defining a minimum width in spaced relation to the closure and mounting portions.
  • crankcase valve of claim 1 wherein said plurality of valve reeds are connected in common to an innter annular mounting strip and said outer port clo- 6 sure portions being generally circular disc-like members disposed in circumferentially spaced relation and said connecting portion being generally hourglass shaped with curved edges extending between the closure portion and the strip.
  • crankcase valve of claim 1 comprising stop means secured in overlying relationwith each valve reed and spaced outwardly from the valve reed a distance slightly in excess of the normal outward deflection of the corresponding reed.
  • crankcase valve of claim ll including stop means secured in overlying relation witheach valve reed and a resilient damping means secured to the stop means.
  • a crankcase valve reed unit for a valve block adapted tobe mounted within an engine crankcase and having an induction passageway means connected to a port opening from the flat face of the block, comprising an integral flat resilient metal member having an outer closure portion essentially corresponding to a port opening and an inner fixed securement portion connected by a connecting portion to define a valve reed, said reed unit being of a generally uniform thickness, said connecting portion including a reduced width between the closure and securement portions and selected to minimize the spring force and move the reed from a deflected position to the planar sealing position without establishing excessive damaging stresses in the reed.
  • the reed unit of claim 8 including a plurality of said reeds equicircumferentially spaced and connected to an annular mounting strip defining said securement portions by corresponding hourglass shaped connecting portions, said curved edges being defined by circular openings between the connecting portion of adjacent reeds.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Check Valves (AREA)
US00281036A 1972-08-16 1972-08-16 Crankcase valve structure for a two-cycle engine Expired - Lifetime US3815559A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US00281036A US3815559A (en) 1972-08-16 1972-08-16 Crankcase valve structure for a two-cycle engine
FR7329742A FR2196665A5 (fr) 1972-08-16 1973-08-14
BE134625A BE803662A (fr) 1972-08-16 1973-08-16 Structure de soupapes de carter pour moteur a deux temps

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US00281036A US3815559A (en) 1972-08-16 1972-08-16 Crankcase valve structure for a two-cycle engine

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US3815559A true US3815559A (en) 1974-06-11

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BE (1) BE803662A (fr)
FR (1) FR2196665A5 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3248361A1 (de) * 1981-12-28 1983-07-28 Brunswick Corp., 60077 Skokie, Ill. Einlassanordnung fuer einen zweitaktmotor
US4509466A (en) * 1982-08-18 1985-04-09 Alfa Romeo Auto S.P.A. Diesel engine with an effective compression ratio substantially equal to the geometrical compression ratio
US4892066A (en) * 1987-11-19 1990-01-09 Outboard Marine Corporation Multi-cylinder two-stroke engine with reduced cost and complexity
US5251584A (en) * 1990-07-13 1993-10-12 Yamaha Hatsudoki Kabushiki Kaisha Two cycle engine
US5540196A (en) * 1995-10-13 1996-07-30 Ford Motor Company Multi-cylinder internal combustion engine with lower cylinder communication
US5623895A (en) * 1994-02-07 1997-04-29 Yamaha Hatsudoki Kabushiki Kaisha V-type, multi-cylinder, two-cycle engine
US20220282796A1 (en) * 2021-03-05 2022-09-08 Mann+Hummel Gmbh Valve Unit, Filter Head for a Valve Unit, and Filter System

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2689552A (en) * 1950-09-11 1954-09-21 Elmer C Kiekhaefer Reed valve for internal-combustion engines
US2779576A (en) * 1953-06-09 1957-01-29 Morgenroth Henri Charge forming device
US3008459A (en) * 1960-05-25 1961-11-14 Jacobsen Mfg Co Fuel induction system for gasoline engine

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2689552A (en) * 1950-09-11 1954-09-21 Elmer C Kiekhaefer Reed valve for internal-combustion engines
US2779576A (en) * 1953-06-09 1957-01-29 Morgenroth Henri Charge forming device
US3008459A (en) * 1960-05-25 1961-11-14 Jacobsen Mfg Co Fuel induction system for gasoline engine

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3248361A1 (de) * 1981-12-28 1983-07-28 Brunswick Corp., 60077 Skokie, Ill. Einlassanordnung fuer einen zweitaktmotor
US4408579A (en) * 1981-12-28 1983-10-11 Brunswick Corporation Induction system for a two-cycle engine
US4509466A (en) * 1982-08-18 1985-04-09 Alfa Romeo Auto S.P.A. Diesel engine with an effective compression ratio substantially equal to the geometrical compression ratio
US4892066A (en) * 1987-11-19 1990-01-09 Outboard Marine Corporation Multi-cylinder two-stroke engine with reduced cost and complexity
AU608368B2 (en) * 1987-11-19 1991-03-28 Outboard Marine Corporation Multi-cylinder two-stroke engine with reduced cost and complexity
US5251584A (en) * 1990-07-13 1993-10-12 Yamaha Hatsudoki Kabushiki Kaisha Two cycle engine
US5623895A (en) * 1994-02-07 1997-04-29 Yamaha Hatsudoki Kabushiki Kaisha V-type, multi-cylinder, two-cycle engine
US5540196A (en) * 1995-10-13 1996-07-30 Ford Motor Company Multi-cylinder internal combustion engine with lower cylinder communication
US20220282796A1 (en) * 2021-03-05 2022-09-08 Mann+Hummel Gmbh Valve Unit, Filter Head for a Valve Unit, and Filter System
US11649904B2 (en) * 2021-03-05 2023-05-16 Mann+Hummel Gmbh Valve unit, filter head for a valve unit, and filter system

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Publication number Publication date
FR2196665A5 (fr) 1974-03-15
BE803662A (fr) 1973-12-17

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