JP4404348B2 - Auto decompression mechanism for outboard motors for race boats - Google Patents

Description

  The present invention relates to an automatic decompression mechanism for an outboard motor for a racing boat, and more specifically, relates to a decompression mechanism for an outboard motor for a racing boat that is manually started by winding a starting rope around a pulley at the end of a crankshaft. In particular, the present invention relates to an improvement of an automatic decompression mechanism (Japanese Patent Application No. 2003-400357) for an outboard motor for a racing boat, which was previously filed by this patent applicant.

  The starting method of a raceboat outboard motor that places importance on a small, lightweight, and simple structure does not have a starter device such as a cell motor, but winds a rope around a pulley attached to the end of the crankshaft only at the start. The mainstream is a rope start system that starts by applying a rotational motion to the crankshaft by pulling.

  Further, the outboard motor for a race boat has a low actual compression and is mainly a two-stroke engine in which an explosion occurs once per one rotation of the crankshaft.

  Conventionally, there are decompression mechanisms for outboard motors, but most of them are linked with recoil starters and use centrifugal force due to rotation of the crankshaft. It is difficult to fit these features in space.

As an auto decompression mechanism,
JP-A-1-53058 (Japanese Patent No. 2524168), engine starting device, No. 7-24624, engine start safety device for work vehicle, No. 6-49900, internal combustion engine recoil starter interlocking start depressurization device, 2-144665 (Registered No. 2519363), recoil motion starting decompressor for internal combustion engine, JP-A-1-318759, (Patent No. 2527808), a manually driven starter for an internal combustion engine, 4-93963 (Registration No. 2517631), engine decompression device, 5-92470, engine decompression device, Utility Model Registration No. 3020094, Engine Stop Device in Tiller, JP-A-7-197875, (Patent No. 2790427), decompression mechanism of engine with recoil starter, JP-A-8-144901 (Patent No. 3103000), internal combustion engine with decompression device, Japanese Patent Application Laid-Open No. 7-224745, a pressure reducing valve for a manually started internal combustion engine for hand-held work equipment Special table 2001-500209, an automatic decompression device, etc. are mentioned.

  However, the actual compression pressure of the 4-stroke engine is higher than that of the 2-stroke engine, and there is also a driving resistance due to the valve mechanism that the 2-stroke engine does not have. The force required to provide is significantly increased compared to conventional two-stroke engines.

  In a four-stroke engine, the number of explosions may be halved compared to a two-stroke engine, and even if the same amount of rotational motion is applied to the crankshaft, the probability of starting is halved. Especially in engines with crankshafts with unequally spaced explosions, depending on the valve timing and ignition timing at the time of start-up, the explosion force may act on the piston before compression top dead center, leading to reverse rotation phenomenon etc. It will be difficult.

  At the start of the rope, the force to reverse the rotation and return to the compression works, so even a healthy man will have a hard time. On the other hand, when stopping the engine during the race, it is necessary to be able to restart immediately from the viewpoint of avoiding danger, and there are also female athletes who are small and weak in arm strength, which is good for outboard motors for race boats. Startability has always been demanded.

  However, when a cell motor is installed to improve startability, the weight of the outboard motor mounted at the end of the ship is increased for lightweight race boats. It has a great influence on the boat's sailing performance. In addition, there is a concern that troubles due to the addition of wiring of the electric system and, in the worst case, an accident during the race due to the electric system may occur.

  In order to overcome the difficulty of starting as described above, the present invention provides a raceboat outboard motor that is manually started by winding a starting rope around a pulley attached to an end of a crankshaft. The decompression lever that is pressed in place by pressing the exhaust rocker arm during the compression stroke lifts the exhaust valve and releases part of the compressed air-fuel mixture to reduce the compression pressure. When the lubricating oil pump is driven and the lubricating oil pressure rises after the engine starts, the piston that slides with the hydraulic force moves away from the exhaust rocker arm to push the decompression lever, and the decompression mechanism is released, and the normal When the engine is stopped, the engine stops, and the lubricating oil pressure decreases, the compression force is applied by the spring force. Over returns to the initial position, it is an auto-decompression mechanism race boat outboard motor as again decompression mechanism shifts to the standby state.

The gist of the invention is a two-cylinder four-stroke outboard motor for a racing boat that is started by a rope start method, a cylinder head, a cam shaft provided vertically in the longitudinal direction in the cylinder head, and the cam shaft. The intake rocker shaft and the exhaust rocker shaft provided in parallel adjacent to each other in the axial direction, and the upper cam provided on the upper end portion, the middle portion, and the lower end portion of the intake rocker shaft, the cam shaft, and the exhaust rocker shaft, respectively. A cap, an intermediate cam cap, a lower cam cap, a timing gear flange provided at the upper end of the camshaft, and a first oil sump formed in the axial direction from near the upper end of the camshaft; a reservoir second oil formed in the axial direction from near the lower end, the first intake provided in the oil sump ambient of the first A cam, and a first exhaust cam provided adjacent to the lower side of the first intake cam around the first oil reservoir, adjacent to the lower side of the first exhaust cam, the cam shaft axis A first guide groove having a required width formed, a first annular stopper provided at a position adjacent to the lower end side of the first guide groove, and a fixed distance from the first annular stopper. A second annular stopper provided; a second guide groove having a required width formed in the camshaft axial direction adjacent to the lower side of the second annular stopper; and adjacent to a lower end portion of the second guide groove and, a second exhaust cam kicked set around the second oil sump, and the second intake cam provided adjacent to the lower side of the second exhaust cam around the second oil reservoir, the Fitted slidably from the center of the first oil sump to the first piston sliding hole formed at the center of the first guide groove. One end is pivotally supported slightly outward from the longitudinal centerline of the camshaft in the first guide groove , the upper surface side in the vertical direction is in contact with the first piston, and the other end is A first decompressor that is always pressed in the direction of the first exhaust cam by a return spring, and a second piston sliding hole formed in the center of the second oil sump from the center of the second guide groove. A second piston fitted to the second shaft, one end pivoted slightly outward from the longitudinal center line of the camshaft in the second guide groove, the lower surface in the vertical direction is in contact with the second piston, and the other A second decompressor whose end is always pressed in the direction of the second exhaust cam by a return spring and the intake rocker shaft are provided adjacent to the upper cam cap, and one end is in contact with the first intake cam of the cam shaft and, the first to the other end A first intake rocker arm connecting the ends of the air valve shaft direction, the exhaust disposed adjacent to the upper cam cap rocker shaft, the first of the cam shaft at the start of the first slipper end engine after starting with contact with the decompression lever is in contact with the first exhaust cam, and a first exhaust rocker arm which is connected to an end portion of the first exhaust valve axis at the other end, to said lower cam cap with said intake rocker shaft A second intake rocker arm provided adjacent to the camshaft and having one end in contact with the second intake cam of the camshaft and the other end connected to an end in the axial direction of the second intake valve; provided adjacent to the cam cap, after start-up with second slipper end is in contact with the second decompression lever of the cam shaft when the engine is started and the second exhaust cam Touch to consists of a second exhaust rocker arms connecting the end of the second exhaust valve axis at the other end, during the compression stroke at the time of starting the engine, first and second Dekon pre bars first And by lifting the second exhaust rocker arm, the first and second exhaust valves are opened, and part of the compressed air-fuel mixture in the combustion chamber is released to reduce the compression pressure, thereby reducing the force required for the rope start. to permit easy start-up, the first and second pistons of the cam in the shaft with a force by the lubricating oil pressure after the engine start is increased to slide the first and second piston sliding hole, said If 1 and the first and second Dekon pre bars pushed by the second piston away respectively against the pressing force of the return spring from the first and second exhaust cam, normal operation decompression mechanism is released State, and When down is stopped the lubricating oil pressure drops, the first and second Dekon pre bars by the pressing force of the return spring is pushed back to its pre-start position, racing boat to standby state before starting the decompression mechanism again This is an automatic decompression mechanism for a two-cylinder four-stroke outboard motor.

(1) As described above, in the two-cylinder four-stroke outboard motor for a racing boat according to the present invention, if the lubricating oil pressure is effectively utilized, the engine is not enlarged and complicated, and a simple starter The engine can be easily started with a force equal to or less than that of a conventional two-stroke engine.

  (2) Therefore, even a female athlete who is small and has little arm strength can start the outboard motor for a race boat safely and easily by a rope start.

  In the racing boat outboard motor having the decompression mechanism according to the present invention, during the compression stroke in the engine starting process, the decompression lever lifts the exhaust rocker arm to open the exhaust valve, and a part of the compressed mixture To reduce the compression pressure, reduce the force required for starting, and enable easy starting.

  The lubricating oil pressure rises after the engine starts, but when the piston in the camshaft slides due to the force of this oil pressure and the decompression lever is pushed down and leaves the exhaust rocker arm, the decompression mechanism is released and the normal pressure is released. Transition to the operating state. When the engine is stopped and the hydraulic pressure is reduced, the decompression lever is pushed back to the position before the start by the force of the return spring, and the decompression mechanism is again put into a standby state before the start.

1 to 8, a camshaft 14 is provided in the vertical direction over the longitudinal direction in the cylinder head 10, and the intake rocker shaft 16 and the exhaust gas are disposed at a certain interval on both sides adjacent to the axial direction of the camshaft 14. The rocker shaft 30 is disposed in parallel and oppositely, and an upper cam cap 34a and an intermediate cam cap are provided at the upper, middle and lower ends of the intake rocker shaft 16, the cam shaft 14 and the exhaust rocker shaft 30, respectively. 34b and the lower cam cap 34c are fixed to each other.

  2 is a cross-sectional view taken along the line III-III showing the second decompression mechanism of FIG. 1 showing the auto decompression mechanism with the cylinder head cover of the raceboat outboard motor according to the present invention removed, while the first decompression mechanism. As shown in FIGS. 3, 4, and 5, the cross section taken along the line II-II showing is a cross section delayed by 90 ° with respect to FIG.

3 and 5, the camshaft 14 forms a first oil sump 14c having a required diameter in the axial direction from near the upper end thereof, and the first oil sump 14c has a first intake cam 14d around it . A first exhaust cam 14e is provided adjacent to the lower side, and an oil filling hole 14b is formed at a corresponding position by the first oil sump 14c.

A first guide groove 14g is formed from the first exhaust cam 14e in the axial direction from the first exhaust cam 14e in the cam shaft 14, and adjacent to the lower end side of the first guide groove 14g, a peripheral middle portion of the cam shaft 14 is formed. The first ring-shaped stopper 14i is protruded from the first ring-shaped stopper 14i, and the second ring-shaped stopper 14j is protruded at regular intervals relative to the first ring-shaped stopper 14i.

Bored a first piston sliding hole 14f from the center of the upper hollow portion 14c in the center of the first guide grooves 14 g, fitting the first piston 14h slidably within the first piston sliding hole 14f Match.

  A holding pin 14k projecting perpendicularly below the center line in the longitudinal direction in the first guide groove 14g is fixed to the pin through hole 18a drilled near the lower end of the first decompressor 18 so that the first decompressor 18 and the annular stopper 14i are provided with a return spring 14m, pivotally supported by the first holding pin 14k as a fulcrum, and the first decompressor 18 is always pressed in the direction of the first exhaust cam 14e to counterclockwise. To be partially rotatable.

  As shown in FIG. 5, a second guide groove 14o is formed in the camshaft 14 adjacent to the second annular stopper 14j from the axial center line, and the second guide groove 14o is pinned in a vertical plane. The second decompressor 14p having the through hole 14q is slidably penetrated, and the holding pin 14r is penetrated into the pin through hole 14q.

A second exhaust cam 14s and a second intake cam 14t are provided adjacent to each other at a position adjacent to the second guide groove 14o on the peripheral surface of the cam shaft 14, and the cam shaft 14 of the second exhaust cam 14s is provided. A second lower oil sump 14u having a required diameter is formed from the portion corresponding to the axially intermediate portion toward the lower end portion, and the second lower oil sump 14u is formed at the center between the second guide groove 14o and the second oil sump 14u . bored piston sliding hole 14v, the second piston 14w fitted slidably in said second piston sliding hole 14v, thereby contacting the distal end of the second piston 14w and second decompression lever 14p .

1 and 2, the intake rocker shaft 16 is provided with the first intake rocker arm 16a adjacent to the upper cam cap 34a, and one end of the first intake rocker arm 16a is brought into contact with the first intake cam 14d. The axial end of the first intake valve 36 is connected to the other end.

The first exhaust rocker arm 30a adjacent the upper cam cap 34a provided in the exhaust rocker shaft 30, a first scan ripper 30a 'to pivot the first exhaust cam 14e and the retaining pin 14k of the cam shaft 14 The first decompressor 18 that is partially rotatable is brought into contact with the other end, and the axial end of the first exhaust valve 38 is connected to the other end.

In the exhaust rocker shaft 30, a second exhaust rocker arm 30c provided adjacent to said lower cam cap 34c, the second scan ripper 30c 'is brought into contact with the second decompression lever 14p of the cam shaft 14, the other end The end of the second exhaust valve 30b in the axial direction is connected to the second exhaust valve 30b.

Clearance adjustment between the axial end of the intake valve 16b connected to the first intake rocker arm 16a and the axial end of the first exhaust valve 38 connected to the first exhaust rocker arm 30a The screws 16b 'and 30b' are screwed together to adjust the clearance.

On the other hand, the second decompression lever 14p a second scan ripper 30c of the retaining pin 14r of the second decompression lever 14p provided adjacent the lower end of the middle The inter cam cap 34b with the exhaust rocker shaft 30 as a fulcrum 'Contact with.

At the start of the engine, when the cam shaft 14 by the rotational movement transmitted from the crank shaft rotates, the first decompression lever 18 and the second decompression lever 14p in the compression stroke first scan ripper 30a 'and said 2 The slipper 30c ′ is pushed up at each timing , so that the first exhaust rocker arm 30a and the second exhaust rocker arm 30c open the first exhaust valve 38 and the second exhaust valve 30b at each timing, and combustion The compression pressure is reduced by releasing a part of the compressed air-fuel mixture in the room, and the first exhaust valve 38 and the second exhaust valve 30b are closed during the operation of the decompression mechanism.

  This timing is before the compression top dead center, and the air-fuel mixture remaining in the combustion chamber is compressed enough to start the engine.

5, the and the oil is filled in the cam shaft 14 the first oil sump 14c and the second oil reservoir 14u of the first piston 14h in the first piston sliding hole 14f is the first decompression cam 18 is pressed in the direction of always first exhaust cam 14e by the return spring 14m, the second piston 14w in the second piston sliding hole 14v corresponds the second decompression lever 14p the The return spring on the second decompressor 14p side always presses in the direction of the second exhaust cam 14s .

When the engine is started, the oil pump is driven, and oil flows into the first oil reservoir 14c from the oil filling hole 14b, the force applied to the first piston 14h is increased by the force of the lubricating oil pressure, and this is the return. The first and second decompressor 18 and 14p fall against the holding pins 14k and 14r as fulcrums against the pressing force of the spring 14m, and are separated from the first and second exhaust rocker arms 30a and 30c, respectively. The mechanism is released and the engine transitions to a normal operating state.

  The lubricating oil pressure when the decompression mechanism is released is set to a value lower than the oil pressure during idling operation, and the decompression mechanism is released at the start. For this reason, the decompression mechanism works during idling or normal operation to avoid unstable rotation.

When the driving of the oil pump is stopped by the engine stop, the lubricating oil is reduced. At this time, when the pressing force of the return spring 14m exceeds the force of pressing the first and second pistons 14h and 14w by hydraulic pressure, the first and second decompressor 18 and 14p are at positions before starting. Returning to the side of the exhaust cams 14e and 14s, the decompression mechanism enters a standby state.

These are the expansion schematic perspective views which show the auto decompression mechanism which removed the cylinder head cover of the outboard motor for race boats concerning this invention. FIG. 3 is a partially enlarged schematic cross-sectional view of the II-II line and the III-III line part of FIG. 1 when the decompression mechanism is activated. FIG. 3 is an enlarged front view of a camshaft taken out from the cylinder head of FIG. 2. FIG. 4 is a partially transparent right side view of the camshaft of FIG. 3. FIG. 5 is a schematic cross-sectional view taken along the line V-V of the camshaft in FIG. 4. FIG. 6 is a schematic cross-sectional view taken along the line VI-VI of the camshaft of FIG. 3. These are the VII-VII sectional view schematics of the cam shaft of FIG. 3 at the time of a decompression mechanism action | operation. These are the VIII-VIII sectional view schematics of the cam shaft of FIG. 3 at the time of cancellation | release of a decompression mechanism.

10 cylinder head;
14 camshaft;
14a timing gear flange;
14b oil filling hole;
14c first oil sump;
14d first intake cam;
14e first exhaust cam;
14f first piston sliding bore;
14g first guide groove;
14h first piston;
14i first annular stopper;
14j second annular stopper;
14k retaining pin;
14m return spring;
14o second guide groove;
14p second decompressor;
14q pin through hole;
14r retaining pin;
14s second exhaust cam;
14t second intake cam;
14u second oil sump;
14v second piston sliding bore;
14w second piston;
16 intake rocker shaft;
16a first intake rocker arm;
16b second intake valve;
16b 'clearance adjustment screw;
16c second intake rocker arm;
18 First decompressor;
18a pin through hole;
30 exhaust rocker shaft;
30a first exhaust rocker arm;
30a 'first scan Ripper;
30b second exhaust valve;
30b 'clearance adjustment screw;
30c second exhaust rocker arm;
30c 'second scan Ripper;
34a upper cam cap;
34b intermediate cam cap;
34c lower cam cap;

Claims (1)

In a two-cylinder four-stroke outboard motor for a race boat that is started by a rope start method, a cylinder head, a cam shaft provided in a vertical direction over a longitudinal direction in the cylinder head, and an axial direction of the cam shaft An intake rocker shaft and an exhaust rocker shaft provided in parallel adjacent to each other, and an upper cam cap and an intermediate portion respectively provided at the upper end portion, the middle portion, and the lower end portion of the intake rocker shaft, the cam shaft, and the exhaust rocker shaft. A cam cap, a lower cam cap, a timing gear flange provided at the upper end of the cam shaft, a first oil sump formed in the axial direction from near the upper end of the cam shaft, and from near the lower end; a reservoir second oil formed in the axial direction, a first intake cam provided in the oil sump ambient of said first, said A first exhaust cam provided adjacent to the first lower side of the intake cam in the first oil reservoir ambient, adjacent to the lower side of the first exhaust cam, which is formed on the camshaft axis direction required A first guide groove having a width, a first annular stopper provided at a position adjacent to the lower end side of the first guide groove, and a first guide groove provided at a fixed interval from the first annular stopper. Two annular stoppers, a second guide groove having a required width formed in the camshaft axial direction adjacent to the lower side of the second annular stopper, and adjacent to a lower end portion of the second guide groove, and a second oil sump second exhaust cam kicked set around, and the second intake cam provided adjacent to the lower side of the second exhaust cam around the second oil sump, said first oil the first piston sliding hole from the center of the reservoir is formed at the center of the first guide groove slidably fitted in And first piston, one end slightly outward from the longitudinal center line of the cam shaft within the first guide groove is pivotally supported, a vertically upper surface side in contact with the first piston, the other end constantly by the return spring a first decompression lever is pressed to the first exhaust cam direction, slidably fitted from the center of the second guide groove in the second piston sliding hole formed in the center of the second oil reservoir and a second piston, one end slightly outward from the longitudinal center line of the cam shaft within the second guide groove is pivotally supported, vertically lower side is in contact with the second piston, the other end return spring And a second decompressor that is always pressed in the direction of the second exhaust cam, and an intake rocker shaft that is adjacent to the upper cam cap, one end of which is in contact with the first intake cam of the cam shaft and the other end the first intake Bal to A first intake rocker arm having an axial end connected thereto and an exhaust rocker shaft adjacent to the upper cam cap, and a first slipper at one end of the first decompressor of the cam shaft when the engine is started after starting with contact with the lever in contact with the first exhaust cam, and a first exhaust rocker arm which is connected to an end portion of the first exhaust valve axis at the other end, adjacent to said lower cam cap with said intake rocker shaft and provided, at one end is in contact with the second intake cam of the cam shaft, the second intake rocker arm which is connected to an end portion of the second intake valve axis in the other end, said lower cam in the exhaust rocker shaft provided adjacent to the cap, after start-up with second slipper end is in contact with the second decompression lever of the cam shaft at the start of the engine is contacted with said second exhaust cam Consists of a second exhaust rocker arms connecting the end of the second exhaust valve axis at the other end, during the compression stroke at the time of starting the engine, first and second Dekon pre bar first and the 2 Open the first and second exhaust valves by lifting the exhaust rocker arm, and release part of the compressed air-fuel mixture in the combustion chamber to reduce the compression pressure, thereby reducing the force required for the rope start. enables easy start-up, the first and second pistons of the cam in the shaft with a force by the lubricating oil pressure after the engine start is increased to slide the first and second piston sliding hole, said first and When the first and second Dekon pre bars pushed by the second piston away respectively against the pressing force of the return spring from the first and second exhaust cam, the decompression mechanism is released to normal operating conditions Migrate and engine When the lubricating oil is lowered down, the first and second Dekon pre bars by the pressing force of the return spring is pushed back to its pre-start position, two-cylinder racing boat to standby state before starting the decompression mechanism again Auto-decompression mechanism for 4-stroke outboard motors.