TWI451031B - Engine decompression mechanism - Google Patents

Description

Engine decompression mechanism

The present invention relates to an engine pressure reducing mechanism, and more particularly to an engine pressure reducing mechanism that is actuated by the principle of gear rack motion.

When the engine is turned off, the engine will continue to rotate a number of revolutions due to the inertia of the rotating motion of the crankshaft. During this process, there are many impedances that cause the rotation to gradually slow down and finally stop. The largest impedance is the compression pressure of the compression stroke, so the engine is often subjected to the compression pressure to cause the normal rotation to stop and then reverse, and then stop.

When the internal combustion engine is to be restarted, the piston in the cylinder moves toward the combustion chamber. At this time, since the intake valve of the intake valve connecting rod and the exhaust valve of the exhaust valve connecting rod are both closed, the piston moves. At this time, the pressure of the compressed gas in the combustion chamber must be overcome to complete the movement of the remaining portion. That is to say, whether it is started by electric motor or manually applied, it must provide sufficient gas pressure to overcome the pressure in the combustion chamber. Otherwise, if the electric motor is started, the electric motor must be designed to have large horsepower and cannot be miniaturized. If it is started by manual force, for example, when it is necessary to step on the engine of the engine car, it will cause the pedaling to be difficult and increase the burden on the user.

In order to address the above pressure problems, some internal combustion engines are currently equipped with so-called pressure reducing devices, which can reduce the pressure of the internal combustion engine at the start to avoid the above problems.

As is known, in order to reduce the above-mentioned compression pressure problem, some engines are equipped with a clutch type decompression device, and the centrifugal force generated by the centrifugal weight when the cam shaft rotates is controlled to have a decompression device at a specific rotation speed. The effect, while above this specific speed, loses the decompression effect.

Conventional pressure reducing devices are mostly multi-link designers. For example, it is a conventional technique to use a link mechanism to drive a pressure reducing cam to achieve engine decompression. The above-mentioned conventional pressure reducing device can be found in the pressure reducing device disclosed in Japanese Laid-Open Patent Publication No. 2006-144627, which has a complicated mechanism, a large number of transmission fulcrums, and poor positioning, and is required to be disposed at the end of the cam shaft. The use of a longer shaft member is not conducive to miniaturization of the overall size.

The engine pressure reducing mechanism of the present invention comprises a cam shaft, a body, a centrifugal weight, an elastic member, and a pressure reducing rod. The camshaft is fixed with a valve moving cam, and the body is fixed to the camshaft.

The centrifugal weight is slidably disposed on the body and includes a first tooth portion. One end of the elastic member abuts against the centrifugal weight to impart a preload in a direction parallel to the sliding of the centrifugal weight.

The pressure reducing rod includes a cam portion and a second tooth portion. The second tooth portion is engaged with the first tooth portion, and the cam portion rotates along with the sliding of the centrifugal weight, and the pressure reducing function is selectively performed.

According to the above mechanism design, the centrifugal weight of the pressure reducing mechanism drives the pressure reducing rod, that is, the sliding motion, in a novel and different manner, and the gear transmission mechanism is also designed according to the conventional linkage mechanism. The advantage of simplicity is that, by the size arrangement relationship of the gear transmission mechanism, the angle required for the centrifugal weight to move a small distance can be used to rotate the pressure reducing rod, and the overall size and device space of the mechanism can be easily achieved. In addition, with the present invention, it is possible to achieve a smaller number of parts and an unrestricted component configuration.

The body can be axially disposed with a perforation, and the pressure reducing rod passes through the perforation to avoid any displacement. The elastic member may be a spring. The body can axially protrude with a receiving seat to receive the elastic member. The accommodating seat may have an L-shaped side wall, and the centrifugal weight may further include a sliding portion that abuts against the L-shaped side wall.

The cam shaft may include a driving wheel at the end, and the cam shaft may further include a first bearing between the driving wheel and the body. The camshaft may further include a second bearing system at the other end opposite the drive wheel.

The engine pressure reducing mechanism may further include a cover system and the body axially restraining the centrifugal weight.

1 to 3, respectively, a cross-sectional view of a locomotive engine, an exploded view of a pressure reducing mechanism, and a cross-sectional view of a pressure reducing mechanism of an embodiment. 1 shows an engine structure of a locomotive. The locomotive engine mainly includes a cylinder head 11, a cylinder block 12, and a crankcase 13 in sequence. A cylinder head upper cover 14 is coupled to the top of the cylinder head 11, and a cylinder head side cover 15 is coupled to the cylinder head 11 side. A decompression mechanism (including the camshaft 21) is disposed inside the cylinder head 11, a piston rod set 16 is disposed inside the cylinder block 12, a crank mechanism 17 is disposed inside the crankcase 13, and the crank mechanism 17 is coupled to a transmission mechanism. 18 to transmit the rotational power.

The pressure reducing mechanism further includes a body 24, a centrifugal weight 25, an elastic member 26, a pressure reducing rod 27, and a cover plate 28 in addition to the cam shaft 21. The camshaft 21 is integrally formed with two valve cams 22, 23 for pushing the corresponding rocker arms 32, 33, thereby displacing the exhaust valve and the intake valve (not shown). The cam shaft 21 is fixed at the end with a driving wheel 31, and receives power from the crank mechanism 17 through a transmission member 34 such as a chain, so that the cam shaft 21 rotates synchronously.

The body 24 is provided with a fixing hole 245 at a substantially central position, and the body 24 is sleeved on the cam shaft 21 by a fixing hole 245. In addition, the body 24 further includes an axially convex receiving seat 241, a straight first abutting portion 244, and a through hole 246, wherein the receiving seat 241 is molded to have a structure of the recess 242 to accommodate the aforementioned elasticity. The member 26 has a receiving seat 241 and has an L-shaped side wall as a second abutting portion 243. In this example, the elastic member 26 is a spring.

The centrifugal weight 25 includes a first tooth portion 251, a first sliding portion 252, and an L-shaped second sliding portion 253, wherein the first sliding portion 252 can correspondingly abut against the first abutting portion of the body 24. 244. The second sliding portion 253 can correspondingly abut against the second abutting portion 243 of the body 24. The second sliding portion 253 is further formed with a receiving end 254 extending into the recess 242 to be in contact with one end of the elastic member 26, and the other end of the elastic member 26 is abutted against the body 24.

The front end of the pressure reducing rod 27 has a cylindrical shape and a second tooth portion 272 is engaged with the first tooth portion 251 of the centrifugal weight block 25 at the circumference thereof, and a cam portion 271 is formed at the rear end thereof, for example, a half moon-shaped cross-section structure. . The pressure reducing lever 27 passes through the through hole 246 of the body 24 with the cam portion 271. The pressure reducing lever 27 is driven by the centrifugal weight 25 through the meshing teeth 251, 272.

The cover plate 28 is disposed beside the centrifugal weights 25, and sandwiches the centrifugal weights 25 together with the body 24, and has a function of preventing the centrifugal weights 25 and the elastic members 26 from being axially disengaged.

In addition, a first bearing 29 is further disposed beside the cover plate 28, and a second bearing 30 is disposed beside the outermost valve cam 23, and the second bearing 30 and the driving wheel 31 are respectively located at opposite ends of the cam shaft.

Refer to Figures 4 and 5. When the locomotive engine is below a certain rotational speed or is stopped, the centrifugal weight 25 is moved toward the outside of the recess 242 by the biasing force of the elastic member 26. At this time, by the meshing two tooth portions 251, 272, the pressure reducing lever 27 is pivoted to a first position, that is, the cam portion 271 is higher than the base circle of the valve moving cam 22, as indicated by the height difference H in the figure, The rocker arm 32 can be topped to exert an engine decompression action. On the other hand, the appropriate weight design allows the centrifugal weights 25 to be snapped against the body 24 at this stage without worrying about radial outflow. The arrows in the figure show the direction of movement of the centrifugal weights 25.

Refer to Figures 6 and 7. When the locomotive engine is operated above a certain rotational speed, the centrifugal weight 25 is subjected to centrifugal force sufficient to resist the urging force of the elastic member 26 to cause the force receiving end 254 to move toward the inside of the recess 242. At this time, by the meshing two tooth portions 251, 272, the pressure reducing lever 27 is pivoted to a second position, that is, the cam portion 271 is lower than the base circle of the valve moving cam 22, and the rocker arm 32 is not topped. Engine decompression. Similarly, the centrifugal weights 25 are also designed to be snapped against the body 24 at this stage without radial detachment. The arrows in the figure show the direction of movement of the centrifugal weights 25.

It can be seen from the above that the mechanism of the present invention is designed such that the centrifugal weighting block controls the decompression rod to rotate by sliding the sliding portion against the abutting portion of the body, and then moving through the rack and pinion movement to selectively decompress the engine. .

The invention has the advantages that the required length of the shaft member can be shortened, the overall size of the mechanism can be effectively reduced, and the parts used are less conventional, and thus the assembly steps are reduced.

The above-mentioned embodiments are merely examples for convenience of description, and the scope of the claims is intended to be limited to the above embodiments.

11. . . Cylinder head

12. . . Cylinder block

13. . . Crankcase

14. . . Cylinder head cover

15. . . Cylinder head side cover

16. . . Piston connecting rod set

17. . . Crank mechanism

18. . . Transmission mechanism

twenty one. . . Camshaft

22,23. . . Valve cam

twenty four. . . Ontology

241. . . Housing

242. . . Groove

243. . . Second abutment

244. . . First abutment

245. . . Fixed hole

246. . . perforation

25. . . Centrifugal weight

251‧‧‧First tooth

252‧‧‧First sliding part

253‧‧‧Second sliding part

254‧‧‧ Forced end

26‧‧‧Flexible parts

27‧‧‧Relief rod

271‧‧‧Cam Department

272‧‧‧second tooth

28‧‧‧ Cover

29‧‧‧First bearing

30‧‧‧second bearing

31‧‧‧Drive wheel

32,33‧‧‧ rocker arm

34‧‧‧ Transmission parts

1 is a cross-sectional view of a locomotive engine in accordance with a preferred embodiment of the present invention.

2 is an exploded view of a pressure reducing mechanism in accordance with a preferred embodiment of the present invention.

Figure 3 is a cross-sectional view of a pressure reducing mechanism in accordance with a preferred embodiment of the present invention.

Figure 4 is a front view of the decompression mechanism under decompression of the engine.

Figure 5 is a rear view of the pressure reducing mechanism under decompression of the engine.

Figure 6 is a front view of the decompression mechanism of the engine without decompression.

Figure 7 is a rear view of the decompression mechanism of the engine without decompression.

twenty one. . . Camshaft

22,23. . . Valve cam

twenty four. . . Ontology

241. . . Housing

242. . . Groove

243. . . Second abutment

244. . . First abutment

245. . . Fixed hole

246. . . perforation

25. . . Centrifugal weight

251. . . First tooth

252. . . First sliding portion

253. . . Second sliding portion

254. . . Force end

26. . . Elastic part

27. . . Pressure reducing rod

271. . . Cam section

272. . . Second tooth

28. . . Cover

29. . . First bearing

30. . . Second bearing

31. . . Drive wheel

Claims (7)

An engine pressure reducing mechanism, comprising: a cam shaft having a valve moving cam fixed thereon; a body fixed to the cam shaft; a centrifugal weighting block disposed on the body and including a first tooth portion; An elastic member, one end of which abuts against the centrifugal weight and applies a pre-force in a direction parallel to the sliding weight of the centrifugal weight; and a pressure reducing rod including a cam portion and a second tooth portion, The second tooth portion is engaged with the first tooth portion, and the cam portion rotates with the sliding of the centrifugal weight; wherein the body axially protrudes with a receiving seat for receiving the elastic member, and the receiving seat has an L The side wall, the centrifugal weight further includes a sliding portion that abuts against the L-shaped side wall. The engine pressure reducing mechanism of claim 1, wherein the body is axially disposed with a through hole, and the pressure reducing rod passes through the through hole. The engine pressure reducing mechanism of claim 1, wherein the cam shaft includes a driving wheel at one end. The engine pressure reducing mechanism of claim 3, wherein the camshaft further includes a first bearing between the driving wheel and the body. The engine pressure reducing mechanism of claim 4, wherein the camshaft further includes a second bearing system at the other end opposite to the driving wheel. The engine pressure reducing mechanism according to claim 1, wherein the elastic member is a spring. The engine pressure reducing mechanism of claim 1, further comprising a cover system that axially constrains the centrifugal weight together with the body.