Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02N—STARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR
  • F02N19/00—Starting aids for combustion engines, not otherwise provided for
  • F02N19/004—Aiding engine start by using decompression means or variable valve actuation
• • 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
  • F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
  • F01L1/02—Valve drive
  • F01L1/022—Chain drive
• • 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
  • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
  • F01L13/08—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for decompression, e.g. during starting; for changing compression ratio
• • 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
  • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
  • F01L13/08—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for decompression, e.g. during starting; for changing compression ratio
  • F01L13/085—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for decompression, e.g. during starting; for changing compression ratio the valve-gear having an auxiliary cam protruding from the main cam profile
• • 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
  • F01L2301/00—Using particular materials

Definitions

• the present invention relates to a decompression device that assists a start of a four-stroke cycle internal combustion engine by a star motor.
• the decompression device for opening one of the intake and exhaust valves is operated.
• a mechanical decompression device that sets the decompression device to a non-operating state by the centrifugal force of a weight in the device Japanese Patent Application Laid-Open No. 11-1077-1727, Japanese Patent Application Laid-Open No. 20-210. 0 0—1994 12; see Japanese Patent No. 2890218).
• the decompression device is activated by the excitation of the electromagnetic solenoid, assisting the rotation of the crankshaft, and the internal combustion engine can start rotating independently of the power of the starter.
• An electric decompression device is known in which the operation of the decompression device is released by de-energizing the electromagnetic solenoid after the rotation speed reaches a certain level (see Japanese Patent Application Laid-Open No. Hei 11-324744).
• centrifugal force is used to automatically switch the operation and non-operation of the decompression device. The inertia became large, and a high-output star motor was required, making it difficult to reduce the size of the motor.
• the electromagnetic solenoid may be energized only when the operation of the decompression device is necessary.Thus, it is possible to reduce the size of the decompression device. Requires an electronic judgment device It is difficult to apply to a small four-stroke cycle internal combustion engine that does not have a child controller, and even if it is an internal combustion engine that has an electronic controller, there is a drawback that this electronic controller becomes complicated. Was. Disclosure of the invention
• the present invention relates to an improvement in a decompression device for a four-stroke cycle internal combustion engine that overcomes such difficulties.
• the present invention relates to a four-stroke cycle internal combustion engine, which comprises an intake valve and an air valve that are respectively opened and closed by an intake cam and an exhaust cam integrated with a camshaft, and that is started by a star and a motor.
• a one-way clutch is mounted on the camshaft so as to be rotatable relative to the camshaft, and a one-way clutch is provided adjacent to the decombcam and capable of transmitting a reverse rotation torque to the decompression cam only when the camshaft rotates in the reverse direction.
• a torque limiter for releasing transmission of a reverse torque of a predetermined torque or more is interposed between the decompression cam and the one-way clutch, and is engaged with an engagement portion formed on the decompression cam.
• Part of the decompression cam stopper that locks the decompression cam at two positions in the forward and reverse rotation directions of the decompression cam The lift of the cam portion of the decompression cam is set to be higher than the base circle of the exhaust cam or intake cam and lower than the maximum lift of the cam portion of the exhaust cam or intake cam.
• the exhaust valve or the intake valve is not opened by the decombing cam when the engaging portion is locked to a part of the decompression cam stopper during rotation.
• the present invention is configured as described above, when the star is rotated in the reverse direction, the reverse rotation torque is transmitted from the reversely rotated camshaft to the decompression cam via the one-way clutch and the torque limiter, so that the decompression cam is transmitted. Is reversed, and the engaging portion of the decompression cam is locked to a part of the one decompression cam stopper of the fixed portion. Even if the camshaft is reversed in this locked state, since the torque limiter is present, a large reversing force between the star shaft and the cam is not applied to the camshaft, the decombing cam, the engaging portion, the decombing cam stopper, and the like.
• the decompression cam rotates slightly with the camshaft.
• the decompression cam slightly rotates in the normal rotation direction again, and after this rotation is repeated a plurality of times, the engaging portion of the decompression cam locks the other decompression cam of the internal combustion engine body. And the decompression cam stops at the inoperative position.
• the opening operation of the exhaust valve or the intake valve by the decombing cam is automatically released, and the operation can shift to normal internal combustion engine operation.
• the centrifugal force is not used, the inertia of the valve train is reduced, the size of the star motor can be reduced, and switching from the start operation state to the normal operation state can be performed.
• the control is performed mechanically without using electronic control, the control system of the internal combustion engine can be prevented from becoming complicated, and costs can be reduced.
• the torque limiter can be formed so that the transmission torque when the camshaft rotates forward is small, and the transmission torque when the camshaft rotates reversely is large.
• the torque limiter includes a contact member provided on one of the adjacent side surfaces of the one-way clutch and the decompression cam, a recess provided on the other of the adjacent side surfaces, and a contact member provided on the one side of the decompression cam.
• a spring which presses and biases the cam shaft when the cam shaft rotates in the reverse direction. It can be configured to be formed in a shape that increases the transmission torque applied to it.
• the torque limiter includes a contact member provided on one of the inner and outer peripheral surfaces adjacent to the one-way clutch and the decompression cam, and a concave portion provided on the other of the adjacent inner and outer peripheral surfaces.
• FIG. 1 is a longitudinal sectional view of a four-stroke cycle internal combustion engine provided with an embodiment of the decompression device of the present invention.
• FIG. 2 is a cross-sectional view of the internal combustion engine.
• FIG. 3 is an enlarged cross-sectional view of a main part of the internal combustion engine.
• FIG. 4 is a sectional view taken along the line IV-IV of FIG.
• FIG. 5 is a sectional view taken along line VV of FIG.
• FIGS. 6 (a) and 6 (b) are a front view and a cross-sectional view of an oval recess provided in the decompression cam of the above embodiment.
• FIG. 7 is an operation explanatory view of the above embodiment.
• FIG. 8 is an operation explanatory view of the above embodiment.
• FIG. 9 is an operation explanatory view of the above embodiment.
• FIG. 10 is an operation explanatory diagram of the above embodiment.
• FIG. 11 is a diagram showing the relationship between the crank angle and the valve lifts of the exhaust cam, the intake cam, and the decompression cam.
• FIG. 12 is an enlarged cross-sectional view of a main part of an internal combustion engine according to another embodiment of the present invention.
• FIG. 13 is a cross-sectional view of XIII-XIII of FIG.
• FIG. 14 is a sectional view taken along the line XIV-XIV of FIG.
• FIG. 15 is a development view of a part of the inner surface of the decompression cam. BEST MODE FOR CARRYING OUT THE INVENTION
• the main body of a single-cylinder OHC four-stroke cycle internal combustion engine 1 equipped with the decompression device of the present invention and mounted on a motorcycle includes a cylinder block 2 and a cylinder block 2.
• a cylinder head 3 detachably provided at the upper end and a crankcase (not shown) provided below the cylinder block 2.
• a piston 5 is provided in a cylinder hole 4 of the cylinder block 2.
• the piston 5 is slidably fitted up and down, and the piston 5 is connected to a crankshaft (not shown) via a connecting rod.
• the crankshaft is driven to rotate in conjunction with the elevation of the piston 5. ing.
• An intake passage 7 and an exhaust passage 8 are formed in the cylinder head 3 and communicate with the combustion chamber 6 above the cylinder hole 4.
• the intake passage 7 has an intake valve 9, and the exhaust passage 8 has an exhaust valve 10.
• a valve spring 12 interposed between a retainer 11 integrally mounted on the top of the intake valve 9 and the exhaust valve 10 and a cylinder head 3. Due to the spring force, the intake valve 9 and the exhaust valve 10 are urged to be always closed.
• An upstream side of the intake passage 7 is provided with a throttle valve, a carburetor, and a filter (not shown) toward the upstream side.
• a camshaft 13 is rotatably supported on the cylinder head 3 via a pair of bearings 14 at a center of the space above the intake valve 9 and the exhaust valve 10, and one end of the camshaft 13.
• a driven sprocket 16 is attached to the body by a plurality of ports 15, and an endless chain 17 is bridged between a drive sprocket (not shown) integral with a crankshaft (not shown) and the driven sprocket 16.
• the power shaft 13 is driven to rotate at a rotation speed of 1 Z 2 of the rotation speed of the crankshaft.
• the rocker shaft 18 has an intake rocker arm 19 and an exhaust port locker arm.
• the intake rocker arm 19 and the exhaust rocker arm 20 are screwed at one end with an evening screw 21 and are fixed integrally by a lock nut 22.
• the intake rocker arm 19 and the exhaust An intake port roller 25 and an exhaust roller 26 are rotatably supported via a roller bearing 24 on a roller support shaft 23 fitted to the other forked end of the rocker arm 20. .
• camshaft 13 is formed with an intake cam 27 and an exhaust cam 28 which can come into contact with the intake rocker arm 19 and the intake roller 25 and the exhaust roller 26 of the exhaust rocker arm 20, respectively.
• a one-way latch 29 is fitted on the camshaft 13 at an outer side of the exhaust cam 28, and a decompression cam 38 is rotatably mounted on the small-diameter cylindrical portion 30 of the one-way clutch 29. Fitted.
• FIG. 3 is an enlarged view of the one-way clutch 29, the decompression cam 38 and its adjacent parts shown in FIG. 2
• FIG. 4 is a sectional view taken along line IV-IV of FIG. 3
• FIG. 5 is a sectional view taken along line V-V of FIG.
• three cam notches 32 are formed at equal intervals in the circumferential direction in the large-diameter cylindrical portion 31 of the one-way clutch 29, and the cam rollers 33 are loosely fitted into the cam notches 32, respectively.
• the cam spring 13 is interposed between the cam notch 32 and the cam roller 33 and the camshaft 13 rotates forward (rotation in the direction of the arrow N)
• the one-way clutch 29 is shut off and the camshaft 13 is turned off.
• the one-way clutch 29 is configured to be in a connected state when the motor rotates reversely (rotation in the direction of the arrow R).
• a blind hole 35 is formed in the large-diameter cylindrical portion 31 of the one-way clutch 29 between the adjacent cam notches 32 from the inner surface of the large-diameter cylindrical portion 31 to the outside.
• a coil spring 36 and a pole 37 are loaded in each of the blind holes 35.
• 12 egg-shaped recesses 39 are formed at equal intervals in the circumferential direction, and are pressed toward the decompression cam 38 by the coil spring 36.
• the pole 37 can be fitted into the egg-shaped recess 39 in a state facing the egg-shaped recess 39, as shown in FIG.
• FIG. 6 is a front view and a cross-sectional view of one oval recess 39. This recess is composed of a steep slope 39a and a gentle slope j ⁇ B39b.
• the decompression cam 38 is provided with an engagement projection 41 projecting in a radial direction.
• the cylinder head 3 is provided with a reverse rotation stopper 42 for locking the decompression cam 38 by the engagement projection 41 when the decompression cam 38 reversely rotates, and the intake rocker arm 19 has When the decompression cam 38 rotates forward, a forward rotation stopper 43 for locking the decompression cam 38 by the engagement projection 41 is formed.
• a stopper ring 44 made of synthetic resin is fitted in a ring-shaped concave portion adjacent to the inner edge of the decompression cam 38.
• the spark plug 45 passes through the cylinder head 3 so that the electrode portion 46 of the spark plug 45 projects into the combustion chamber 6, as shown in FIG. It is screwed to the node 3.
• the one-way latch 29 When the camshaft 13 reverses counterclockwise as shown in FIG. 4, the one-way latch 29 also rotates counterclockwise integrally with the camshaft 13 and fits into the blind hole 35 of the one-way clutch 29.
• the pole 37 extruded by the panel force of the coil spring 36 engages the steeply inclined portion 39a of the oval recess 39 of the decompression cam 38 to generate a large transmission torque in the reverse direction of torque reduction 40.
• the reverse rotation torque is transmitted from the one-way clutch 29 to the decompression cam 38, and the decompression cam 38 rotates reversely.
• the decompression cam 38 can reversely rotate in the counterclockwise direction. As shown in FIG. 1, the engagement projection 41 of the decompression cam 38 is locked by the reverse rotation stopper 42, so that Cam 38 stops. In this state, the forked end 20a of the exhaust rocker arm 20 abuts on the cam ridge 38a of the decompression cam 38, and the exhaust valve 10 is slightly opened.
• the reason that the decompression cam 38 rotates together with the camshaft 13 is that the forked end 20a of the exhaust port cocker arm 20 is separated from the cam ridge 38a of the decompression cam 38, that is, the section of the cam angle of the exhaust cam 28. Is only. Thereafter, the cam ridge 28a of the exhaust cam 28 passes the position of the exhaust roller 26, and the exhaust port roller 26 and the dual end 20a of the exhaust rocker arm 20 descend, and as shown in FIG. When the forked end 20a of the hook arm 20 comes into contact with the cam portion 38a of the decompression cam 38, the decompression cam 38 stops due to the rotational resistance torque, and only the camshaft 13, the exhaust cam 28, and the intake cam 27 are moved. Continue normal rotation.
• the camshaft 13 rotates substantially once, and the cam ridge 28a of the exhaust cam 28 comes into contact with the exhaust roller 26 again and pushes it up, thereby forming the forked end 20a of the exhaust port lock arm 20.
• the decompression cam 38 rotates with the camshaft 13 again by the cam angle of the exhaust cam 28.
• Camshaft 13 rotates twice After a few revolutions, the bifurcated end 20a of the exhaust rocker arm 20 comes off the cam peak 38a of the decompression cam 38, and the decompression operation ends.
• the gentle slope portion 39b of the oval concave portion 39 of the decompression cam is a portion for reducing the impact when the decompression cam 38 is locked by the forward rotation stopper 143.
• FIG. 11 shows the relationship between the crank angle and the cam lift of the intake cam, the exhaust cam, and the decompression cam.
• IN is the lift of the intake cam
• EX is the lift of the exhaust cam
• DC is the lift of the decompression cam.
• the exhaust valve opens under the influence of the larger of the exhaust power and the lift of the decompression cam.
• the exhaust valve is opened according to the lift along the curve of A—B—C—D—E—F—G—H—I—J.
• the decompression cam advances to some extent, and when the cam peak comes off the fork of the exhaust rocker arm, the lift becomes closed.
• the weight having a large moment of inertia is not provided in the starting system, and the crankshaft is rotated at a relatively small rotation speed over several rotations.
• the activity can be greatly improved, and the output of the star and the night can be reduced, and the size and the weight of the star and the night can be reduced.
• FIGS. Another embodiment of the present invention will be described with reference to FIGS. This embodiment is different from the above-described embodiment only in the shape of the one-way clutch and the decompression cam, and the other parts have the same configuration. Therefore, the same components are denoted by the same reference numerals.
• FIG. 12 is an enlarged view of a main part of this embodiment.
• a one-way clutch 50 is fitted on the camshaft 13 outside the exhaust cam 28, and a decompression cam 58 is rotatably fitted on the outer peripheral portion 51 of the one-way clutch 50.
• FIG. 13 is a sectional view taken along the line XIII- I of FIG. 12, and
• FIG. 14 is a sectional view taken along the line XIV-XIV of FIG. As shown in Fig.
• FIGS. 12 and 14 As shown in FIGS. 12 and 14, as shown in FIGS. 12 and 14, 12 blind holes 55 that open outward are formed at regular intervals in the outer peripheral portion 51 of the one-way clutch 50. Coil spring 56 and pole 57 are loaded. On the inner peripheral surface of the decombing cam 58, 12 egg-shaped concave portions 59 are formed at regular intervals in the circumferential direction.
• FIG. 15 is a development view of a part of the inner surface of the decompression cam.
• the illustrated concave portion also includes a steeply inclined portion 59a and a gentlely inclined portion 59b, like the concave portion of the above-described embodiment.
• the pawl 57 pressed by the coil spring 56 toward the decompression cam 58 can fit into the oval recess 59 in a state where the pawl 57 faces the oval recess 59.
• the torque limiter 60 is composed of the blind hole 55 of the one-way clutch 50, the coil spring 56, the pawl 57, and the oval recess 59 of the decompression cam 58.
• the decompression cam 58 is provided with a cam crest 58a and an engagement protrusion 61 similar to those of the previous embodiment.
• the engaging projection 61 is locked by the reverse rotation stopper 42 of the cylinder head 3 when the decompression cam 58 rotates in the reverse direction, and is locked by the normal rotation stopper 43 of the intake port car arm 19 when the decompression cam 58 rotates in the normal direction. Part. .
• a stopper ring 62 made of synthetic resin is fitted in a ring-shaped concave portion adjacent to the edge of the decompression cam 58.
• This embodiment shows that the torque limiter can be formed between the outer circumference of the one-way clutch and the inner circumference of the decompression force.
• the decompression cam also rotates in reverse.
• the camshaft rotates forward and the extremity end 20a of the exhaust rocker arm moves away from the force 58a of the decompression cam, the extremely small rotating torque and torque between the camshaft and the one-way clutch.
• the engagement of the limiter rotates the decompression cam forward.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Valve Device For Special Equipments (AREA)
• Output Control And Ontrol Of Special Type Engine (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

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ID=18942110

Family Applications (1)

Country Status (13)

Families Citing this family (15)

Citations (2)

Family Cites Families (3)

• 2001
  • 2001-03-26 JP JP2001086780A patent/JP4338333B2/ja not_active Expired - Fee Related
• 2002
  • 2002-02-22 ES ES02700715T patent/ES2317988T3/es not_active Expired - Lifetime
  • 2002-02-22 DE DE60230541T patent/DE60230541D1/de not_active Expired - Lifetime
  • 2002-02-22 KR KR1020027016050A patent/KR100813746B1/ko not_active IP Right Cessation
  • 2002-02-22 IL IL15276602A patent/IL152766A0/xx not_active IP Right Cessation
  • 2002-02-22 WO PCT/JP2002/001616 patent/WO2002077422A1/ja active Application Filing
  • 2002-02-22 CN CNB028008251A patent/CN1263943C/zh not_active Expired - Fee Related
  • 2002-02-22 EP EP02700715A patent/EP1447530B1/en not_active Expired - Lifetime
  • 2002-02-22 TR TR2002/02556T patent/TR200202556T1/xx unknown
  • 2002-02-22 BR BRPI0204676-8A patent/BR0204676B1/pt not_active IP Right Cessation
  • 2002-03-04 TW TW091103950A patent/TW515863B/zh not_active IP Right Cessation
  • 2002-03-25 AR ARP020101078A patent/AR033203A1/es active IP Right Grant
  • 2002-03-25 MY MYPI20021052A patent/MY135269A/en unknown

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