JP2005248933A - Auto-decompression mechanism for outboard motor for race boat - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an auto-decompression mechanism for an outboard motor for a race boat of such a type that a starting rope is wound around a pulley at an end part of a crankshaft for manual start. <P>SOLUTION: In this auto-decompression mechanism for an outboard motor for a race boat, the starting rope is wound around the pulley at the end part of the crankshaft for manual start. At the time of starting, a decompression lever pressed to a prescribed position by a spring pushes an exhaust rocker arm in a compression stroke to lift an exhaust valve. Part of compression mixed gas is let off to reduce compression pressure so as to reduce force required for starting. As a lubricant pump is driven to increase lubricant pressure after engine start, a piston slid by hydraulic force pushes the decompression lever to be separated from the exhaust rocker arm so as to release the decompression mechanism. In accordance with transfer to normal driving states, with engine stop to decrease lubricant pressure, the decompression lever is returned to an initial position by pressure of the spring, so that the decompression mechanism transfers to a stand-by state. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an automatic decompression mechanism for an outboard motor for a race boat, and more specifically, relates to a decompression mechanism for an outboard motor for a race 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 (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-1-330759, (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. 3030094, Engine Stop Device in Tiller, JP-A-7-197875, a decompression mechanism of an engine with a recoil starter, 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. 7-304745, a pressure reducing valve for a manually started internal combustion engine for hand-held work equipment Special table 3001-500309, 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 rotational motion is applied to the crankshaft, the probability of starting is reduced to half. 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 that tries to reverse the rotation and reverse the compression works, so even a healthy man will have a hard time. On the other hand, when stopping the engine during a 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 the end of a crankshaft. The decompression lever pressed in place by the spring pushes the exhaust rocker arm during the compression process, lifts the exhaust valve, and releases a part of the compressed air-fuel mixture to reduce the compression pressure. When the lubricating oil pump is driven after the engine is started and the lubricating oil pressure rises, the piston that slides with the oil pressure moves away from the exhaust rocker arm to push the decompression lever, and the decompression mechanism is released, When the engine is stopped, the engine is stopped, and the lubricating oil pressure decreases, the compression force is applied by the spring force. Over returns to the initial position, a starting aid race boat outboard motor as again decompression mechanism shifts to the standby state.

  The gist is that a cylinder head, a timing gear flange is fixed to the upper end, an upper oil sump formed in the center direction from near the upper end, a lower oil sump formed in the center direction from near the lower end, and the upper oil sump. A first intake cam provided approximately in the middle of the periphery, a first exhaust cam provided adjacent to the first intake cam around the upper oil sump, and adjacent to the first exhaust cam. A guide groove having a required width formed at the center of the direction, a position adjacent to the guide groove, an annular stopper provided at a fixed interval relative to the required position, and a periphery around the lower oil sump. A second exhaust cam and a second intake cam, a first piston slidably fitted in a through hole formed in the upper oil sump and the guide groove, and a lower end pivotally supported near the lower portion of the gap. The first side is the first pin. A first decompressor whose upper end is always pressed forward by a return spring, and a guide formed from a corresponding position of the annular stopper to a corresponding position of the second exhaust cam in the longitudinal direction of the main body. A second groove is slidably fitted into the sliding hole formed in the lower oil sump from the guide groove, the front end contacts the second decompressor, and the rear end faces the lower oil sump. A camshaft having a piston and provided in the longitudinal direction in the cylinder head; and an intake rocker shaft and an exhaust rocker shaft provided adjacent to and centered on the camshaft and parallel to and slightly from the upper part and the lower part; An upper cam cap and an intermediate cam cap provided on the upper end, the middle and the lower end of the camshaft, the intake rocker shaft and the exhaust rocker shaft, respectively. And a lower cam cap; a first intake that is provided adjacent to the upper cam cap on the intake rocker shaft, one end of which is in contact with the first intake cam of the cam shaft and the other end of which is connected to the upper end of the intake valve A rocker arm; provided on the exhaust rocker shaft adjacent to the upper cam cap, with a first large slipper at one end contacting the first decompressor of the camshaft and connecting the upper end of the exhaust valve to the other end A first exhaust rocker arm; a second exhaust rocker shaft provided adjacent to the lower cam cap and having one end in contact with the second intake cam of the cam shaft and the other end connected to the upper end of the intake valve An intake rocker arm and an exhaust rocker shaft are provided adjacent to the lower cam cap, and a second large slipper at one end is connected to the second decompressor of the camshaft. This is a start assist mechanism for an outboard motor for a racing boat, which is composed of a second exhaust rocker arm that contacts the lever and has the other end connected to the upper end of the exhaust valve.

(1) As described above, in the four-stroke outboard motor for a racing boat according to the present invention, if the lubricating oil pressure is effectively used, the engine is not enlarged and complicated, and a simple starter The engine can be started easily with the same or less force than the conventional 2-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, the decompression lever lifts the exhaust rocker arm during the compression process in the engine starting process, thereby opening the exhaust valve and A part is released to reduce the compression pressure, and the force required for starting is reduced to 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 pushed by the piston falls off 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 cam shaft 14 is provided in the cylinder head 10 in the longitudinal direction, and the intake rocker shaft 16 and the exhaust rocker shaft 30 are parallel to each other at a predetermined interval adjacent to the cam shaft 14. The upper cam cap 34a, the intermediate cam cap 34b, and the lower cam cap 34c are provided at the upper, middle, and lower ends of the intake rocker shaft 16 and the exhaust rocker shaft 30, respectively. Fix it.

  3 and 5, the camshaft 14 forms an upper oil sump 14c having a required diameter in the central direction from the vicinity of the upper end of the camshaft 14, and the upper oil sump 14c is adjacent to each other in the middle portion of the periphery. An intake cam 14d and a first exhaust cam 14e are provided, and an oil filling hole 14b is formed at a corresponding position by the upper oil reservoir 14c.

  A guide groove 14g is formed in the camshaft 14 from the first exhaust cam 14e from the longitudinal center, and a pair of annular stoppers 14i is formed at a constant interval at a peripheral middle portion of the camshaft 14 at the tip of the guide groove 14g. , 14j.

  A first piston sliding hole 14f is drilled from the center of the upper hollow portion 14c to the center of the guide groove 14g, and the first piston 14h is slidably fitted into the first piston sliding hole 14f.

  A holding pin 14k projecting at a right angle slightly below the longitudinal center line in the guide groove 14g is fixed to the pin through hole 18a drilled near the lower end of the first decompressor 18, and the first decompressor 18 and A return spring 14m is provided between the annular stoppers 14i, pivoted around 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 and partially counterclockwise. Rotate.

  A guide groove 14o is formed in the camshaft 14 adjacent to the annular stopper 14j from the longitudinal center line, and a second decompressor 14p having a pin through hole 14q formed in a vertical plane in the guide groove 14o is slid. It penetrates freely and penetrates the holding pin 14r 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 guide groove 14o on the peripheral surface of the camshaft 14, and the second exhaust cam 14o is intermediate in the longitudinal direction of the camshaft 14. A lower hollow portion 14u having a required diameter is formed from a position corresponding to the portion toward the lower end portion, and a piston sliding hole 14v is formed at the center between the guide groove 14o and the lower oil sump 14u. The second piston 14w is slidably fitted in the moving hole 14v, and the tip of the second piston 14w is brought into contact with the second decompressor 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, one end of the latter is in contact with the intake cam 14d, and the other end is an intake valve. The upper end of 16b is connected.

  The exhaust rocker shaft 30 is provided with a first exhaust rocker arm 30a adjacent to the upper cam cap 34a, and the first large slipper 30a 'is supported by the first exhaust cam 14d and the holding 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 upper end of the exhaust valve 30b ′ is connected to the other end.

  A second exhaust rocker arm 30c is provided on the exhaust rocker shaft 30 adjacent to the lower cam cap 34, and a second large slipper 30c ′ is brought into contact with the second decompressor 14p of the camshaft 14 at the other end. The upper end of the second exhaust cam 14s is connected.

  Clearance adjusting screws 16b 'and 30b' are respectively connected to the upper end of the intake valve 16b connected to the first intake rocker arm 16a and the upper end of the exhaust valve 30b connected to the first exhaust rocker arm 30a. Screw to adjust the clearance.

  On the other hand, the holding pin 14r of the second decompressor 14p provided on the exhaust rocker shaft 30 adjacent to the lower end side of the intermediate cam cap 34b is brought into contact with the second large slipper 30c ′.

  When the engine is started, when the camshaft 14 is rotated by the rotational motion transmitted from the crankshaft, the first decompressor 18 pushes up the first large slipper 30a ′ during the compression process, thereby the first exhaust rocker. The arm 30a opens the exhaust valve 30b to release a part of the compressed air-fuel mixture, thereby reducing the compression pressure, and the exhaust valve 30b is 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.

  In FIG. 5, oil is filled in the upper oil reservoir 14c and the lower oil reservoir 14u of the camshaft 14, and the first piston 14h in the first piston sliding hole 14f is connected to the first decompression cam. 18 is pressed to the right in the longitudinal direction, and the second piston 14w in the second piston sliding hole 14v presses the second decompressor 14p to the left in the longitudinal direction.

  When the engine is started, the oil pump is driven, and oil flows into the upper oil reservoir 14c from the oil filling hole 14b, the force applied to the first piston 14h increases as the lubricating oil pressure rises, and this is the return spring. When the pressing force of 14 m is overcome, the first and second decompressor bars 18 and 14p fall with the holding pins 14k and 14r as fulcrums and separate from the first and second exhaust rocker arms 30a and 30c, so that the decompression mechanism is released. Then, the engine shifts 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 drive of the oil pump is stopped by stopping the engine, the lubricating oil pressure decreases. At this time, when the force of the return spring 14m exceeds the force of pushing the first and second pistons 14h and 14w by hydraulic pressure, the first and second decompressors 18 and 14p are in the positions before starting. Returning to the side of the 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. These are the II-II line partial expanded sectional schematic drawings of FIG. 1 at the time of a decompression mechanism action | operation. 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.

Explanation of symbols

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

Claims (1)

  A cylinder head and a timing gear flange are fixed to the upper end, and an upper oil sump formed in the center direction from near the upper end, a lower oil sump formed in the center direction from near the lower end, and the middle around the upper oil sump. A first intake cam provided in a portion, a first exhaust cam provided adjacent to the first intake cam around the upper oil sump, and adjacent to the first exhaust cam and formed at the center in the longitudinal direction of the main body A guide groove having a required width, a position adjacent to the guide groove, and an annular stopper provided at regular intervals relative to the required position, and a second exhaust cam provided adjacent to the periphery of the lower oil sump. And a second piston, a first piston slidably fitted in a sliding hole formed in the upper oil sump and the guide groove, and a lower end pivotally supported near the lower portion of the guide groove. The side is the first piston A first decompressor whose rear upper end is always pushed forward by a return spring, and a guide groove formed from a corresponding position of the annular stopper to a corresponding position of the second exhaust cam in the longitudinal direction of the center of the main body. A second piston that is slidably fitted into the sliding hole formed in the lower oil sump from the guide groove, has a front end that contacts the second decompressor, and a rear end that faces the lower oil sump. A camshaft provided in the longitudinal direction in the cylinder head; an intake rocker shaft and an exhaust rocker shaft provided adjacent to and centered on the camshaft and parallel to and slightly opposite the upper part and the lower part; Upper cam cap, intermediate cam cap and lower cam provided on the upper end, middle and lower end of the camshaft, the intake rocker shaft and the exhaust rocker shaft, respectively A cam cap; a first intake rocker arm provided on the intake rocker shaft adjacent to the upper cam cap, having one end in contact with the first intake cam of the camshaft and the other end connected to the upper end of the intake valve A first large slipper provided at one end of the exhaust rocker shaft adjacent to the upper cam cap, the first large slipper at one end contacting the first decompressor of the camshaft, and the upper end of the exhaust valve connected to the other end; An exhaust rocker arm; a second intake rocker provided on the intake rocker shaft adjacent to the lower cam cap, one end contacting the second intake cam of the camshaft, and the other end connected to the upper end of the intake valve An arm and an exhaust rocker shaft adjacent to the lower cam cap; a second large slipper at one end connected to the second decompressor of the cam shaft; A start assisting mechanism for an outboard motor for a raceboat, comprising a second exhaust rocker arm that is in contact with and connected to the other end of the exhaust valve at its upper end.