阅读说明：本技术 一种可变压缩比的组合活塞 (Combined piston with variable compression ratio ) 是由 唐为民 于 2020-03-20 设计创作，主要内容包括：一种可变压缩比的组合活塞,它通过相对于活塞本体可以上下移动的活塞盖,改变在最大燃烧压力下燃烧室的容积,从而达到调控最大燃烧压力的目的。与本活塞匹配使用的还有按全密封原理设计的封气环和可以直接形成润滑油膜的布油环。在活塞内部还设有润滑、冷却油路。因此,使用本发明的组合活塞的发动机,适用更高的压缩比,热效率高,燃油耗、机油耗、排污值低,工作寿命长,可望与发动机等寿命。(A combined piston with variable compression ratio features that the piston cover can move up and down relative to piston body to change the volume of combustion chamber under maximal combustion pressure, so regulating the maximal combustion pressure. The piston is matched with an air sealing ring designed according to the full-sealing principle and an oil distributing ring capable of directly forming a lubricating oil film. And a lubricating and cooling oil path is also arranged in the piston. Therefore, the engine using the combined piston is suitable for higher compression ratio, high in heat efficiency, low in fuel consumption, engine oil consumption and pollution discharge value, long in service life and capable of being used as an engine and the like.)

1. A combined piston (1) with variable compression ratio comprises a piston cover (2), a piston upper body (5), a piston lower body (9), a piston rod (11), a central oil pipe (12), an oil distribution pipe (15), one to a plurality of disc springs (3), a supporting pad (4), an oil distribution ring (19), an upper combined gas ring (21) and a lower combined gas ring (18), wherein the piston upper body (5) connects the piston lower body (9) and the piston rod (11) into a whole by screw threads, the piston cover (2) is supported on the top of the piston upper body (5) by the disc springs (3) and the supporting pad (4), the oil distribution pipe (15) sequentially passes through an oil distribution ring groove on one side of the piston lower body (9) to string the piston lower body (9), the piston rod (11), the piston cover (2) and the central oil pipe (12) into a whole and is lapped on the other side of the piston lower body (9), the combination piece of the oil distribution ring is combined with an oil distribution ring (19), an upper combined gas ring (21) and a lower combined gas ring (18) together, and is characterized in that: the piston cover (2) can slide up and down relative to the piston upper body (5) under the maximum combustion pressure, and the engine oil forms a lubricating oil channel and a cooling oil channel in the combined piston (1) through the oil distribution pipe (15) according to an engine oil flow direction mark (13).

2. Piston cover (2) of a variable compression ratio composite piston (1) according to claim 1, characterized in that: the combustion pressure is larger than the maximum compression pressure, corresponding deformation and displacement are generated according to the actual combustion pressure only after the combustion pressure is larger than the maximum compression pressure, and the piston cover (2) is compressed to be overlapped with the upper top surface of the piston upper body (5) until the maximum combustion pressure is reached.

3. A support pad (4) for a combined piston (1) with variable compression ratio according to claim 1 or 2, characterized in that: it is a ring made of copper and graphite.

4. The lubricating oil circuit of the variable compression ratio combined piston (1) according to claim 1, which consists of an oil inlet hole (17) of an oil distribution ring, an oil return hole (8) of the oil distribution ring and an oil distribution ring (20), and is characterized in that: the engine oil enters an oil distribution ring channel (20) on the back of the oil distribution ring from an oil inlet (17), and after the oil is supplied and distributed to an oil distribution ring (19) in the circulation process, the engine oil flows into an annular cooling oil cavity (10) through an oil return hole (8) of the oil distribution ring channel and is part of the total engine oil mass of the cooling piston.

5. The cooling oil circuit of the variable compression ratio combined piston (1) according to claim 1, which has a plurality of oil inlet holes, namely, an oil return hole (8) of an oil distribution ring channel, an oil inlet hole (16) of an annular cooling oil cavity, and an oil spray hole (24) of a conical top of the cooling piston cover (2), and is characterized in that: the engine oil entering the annular cooling oil cavity (10) flows back to the crankcase through an oil return groove hole (22) of the annular cooling oil cavity and an oil return channel (14) between the piston rod and the central oil pipe, wherein the oil in the cooling oil cavity (23) is arranged in the piston cover.

6. A variable compression ratio composite piston (1) according to claim 1 wherein radial blow-off holes (7) are bored in the lands between the upper and lower composite gas rings (21) or (18) and the oil distribution ring (19) and communicate with axial blow-off holes (6) opening to the top face of the piston upper body (5).

Belongs to the technical field of:

the combined piston with variable compression ratio is suitable for reciprocating piston type naturally aspirated or supercharged engines.

Background art:

the compression ratio is an important structural parameter of the engine, and the thermal efficiency of the engine can be improved by increasing the compression ratio, but the improvement of the compression ratio is restricted by the maximum combustion pressure. Therefore, the maximum combustion pressure is regulated and controlled by utilizing the variable compression ratio technology, the maximum combustion pressure is reduced to a safe use range, a higher compression ratio can be possibly adopted, and higher thermal efficiency is obtained.

The invention content is as follows:

the combined piston of the invention uses two patents in a matching way, one is a combined gas ring (patent application number: Z L201810774351.6) designed according to a full-sealing principle, the other is an oil distribution ring (patent number: Z L201520195817.9) capable of directly forming a working oil film, and a lubricating and cooling oil circuit is arranged in the combined piston in a matching way with the patents.

The piston cover of the combined piston mainly has three functions. 1. It is placed on the body of the combined piston with elastic support. The displacement directly causes the volume of the combustion chamber to be changed from a small combustion chamber volume to a relatively large combustion chamber volume under the condition that the displacement of the piston is not changed, and then the maximum compression ratio which can generate the maximum combustion pressure is changed into an actual smaller compression ratio, and the maximum combustion pressure is correspondingly reduced, so that various adverse effects which can be caused by the maximum combustion pressure are avoided, and the main purpose of regulating and controlling the maximum combustion pressure is realized. Because the engine, especially the engine used as a mobile tool, has less running time and generally has not long lasting time under the condition of maximum power, the engine adopts higher compression ratio on the premise of reducing the maximum combustion pressure to a safe use range, and is more beneficial to exerting the comprehensive efficiency of the engine. In addition, on the one hand, the spring supporting the piston cover does not generate compression deformation under the maximum compression pressure, and only after the combustion pressure is greater than the maximum compression pressure, the corresponding compression deformation is generated according to the actual combustion pressure until the maximum combustion pressure is reached, and the piston cover is compressed to be overlapped with the piston body. The actual working state of the combined piston enables the engine to work under a high compression ratio all the time, and the output power is high. On the other hand, the supporting spring also plays a role of energy storage. When the supporting spring is compressed by the maximum combustion pressure, a part of the pressure energy of the maximum combustion pressure is stored in the supporting spring, and the part of the stored energy is released in the expansion stroke of the piston, which is equal to the increase of the isobaric expansion process of the piston, thereby increasing the cycle efficiency of the engine. 2. The piston cover is provided with a conical top which changes the uniform combustion chamber into an annular combustion chamber. The combustion center is dispersed and the maximum operating temperature is relatively low. Meanwhile, because the propagation distance of the flame is short, the whole combustion process can be finished in a smaller crank angle after the top dead center, so that the heat efficiency is high, and the amount of generated NOx is small. 3. The piston cover has a shielding protection effect on the piston body, can effectively prevent high-temperature fuel gas in a combustion chamber from transferring a large amount of heat to the piston body in a direct contact mode, and is provided with a cooling oil cavity in the piston body. When the engine runs under low load, the piston cover is in light contact with the supporting spring, and the heat quantity transmitted downwards through the piston cover is small, so that the engine is beneficial to cold starting and low-speed running. Along with the increase of load, the tighter the piston cover, the supporting spring and the piston body are pressed, the area of direct contact is increased, the heat transmitted out is correspondingly increased, and in addition, the cooling oil cavity is arranged in the piston cover, so the piston cover is made of steel with better heat resistance and higher strength, and the piston cover is not overheated.

The combined gas ring matched with the combined piston of the invention uses the full-sealing principle to replace the multi-ring labyrinth throttling sealing principle of the traditional piston, effectively improves the lubricating condition of a ring, keeps the uniformity and continuity of oil film lubrication, eliminates the dry friction and semi-dry friction phenomena at the ring opening, has good gas sealing performance and less gas leakage of the piston, not only improves the power of an engine, but also effectively lightens the severe pollution of the leaked gas to engine oil, obviously improves the lubricating quality of the engine oil and greatly prolongs the replacement period of the engine oil. The combined gas ring matched with the piston assembly has excellent gas sealing performance, can realize one-ring gas sealing, greatly reduces the structural size and reciprocating inertia mass of the piston assembly, is matched with good lubricating conditions, and greatly reduces the friction loss of the piston assembly compared with the traditional piston. The combined piston has good lubricating and cooling conditions, and the matched combined gas ring has a certain self-compensation function after being worn, so that the combined piston can achieve the ideal effect of prolonging the service life of an engine and the like.

The oil distributing ring matched with the combined piston replaces an oil scraper ring, and a lubricating oil film for ensuring the normal operation of the piston group is directly formed between the piston and the cylinder wall by utilizing the reciprocating motion of the piston, so that the phenomenon that the oil is burnt by the engine oil fleeing in the traditional engine is eliminated, the lubricating quality is better, and the operation resistance of the piston group is lower. On the basis, the oil film thickness can be further optimized, so that the engine oil consumption, the pollution discharge value caused by the engine oil consumption and particulate matters are greatly reduced.

Description of the drawings:

the composite piston of the present invention will be further described with reference to the accompanying drawings and the following detailed description.

Fig. 1 is a front view of a variable compression ratio composite piston of the present invention, showing its structural form.

Fig. 2 is a bottom view of the piston cap.

Fig. 3 is a cross-sectional view through the axis of the oil return slot 22.

Fig. 4 is an oil path for cooling the piston nose cone.

Description of the drawings:

1. a variable compression ratio compound piston; 2. a piston cap; 3. a disc spring; 4. a support pad; 5. a piston upper body; 6. an axial air overflow hole; 7. a radial air overflow hole; 8. an oil distribution loop oil return hole; 9. a piston lower body; 10. an annular cooling gallery; 11. a piston rod; 12. a central oil pipe; 13. an engine oil flow direction indicator; 14. an annular oil return passage; 15. an oil distributing pipe; 16. an oil inlet hole of the annular cooling oil cavity; 17. an oil inlet of the oil distribution loop; 18. a lower combined gas ring; 19. an oil distribution ring; 20. oil distribution loop; 21. an upper combined gas ring; 22. an oil return slot hole of the annular cooling oil cavity; 23. a cooling oil cavity is arranged in the piston cover; 24. and an oil nozzle.

The specific implementation mode is as follows:

as shown in FIG. 1, the variable compression ratio combined piston 1 of the present invention comprises a piston cover 2, an upper body 5 and a lower body 9 of the piston, a piston rod 11, a central oil pipe 12, an oil distribution pipe 15, one or more disc springs 3, a support pad 4, an oil distribution ring 19, and upper and lower combined air rings 21 and 18. The piston upper body 5 of the cooling oil cylinder is connected with the piston lower body 9 and the piston rod 11 into a whole through threads, and an annular cooling oil cavity 10 is formed in the piston upper body and the piston lower body. Its piston cover 2 is supported on the top of piston upper body 5 by means of disk spring 3 and supporting pad 4, and the displacement quantity produced by piston cover 2 under the action of cylinder pressure is equal to deformation quantity of disk spring. When the combustion pressure is higher than the maximum compression pressure of the piston, the belleville springs are compressed and deformed correspondingly according to the actual combustion pressure until the maximum combustion pressure is reached, as shown in fig. 2, the belleville springs are overlapped into the matched concave pits of the piston cover 2, and the piston cover 2 is compressed to be overlapped with the upper top surface of the piston upper body 5. The displacement of the piston cover makes the volume of the combustion chamber change from small to large, and the pressure of the combustion chamber correspondingly decreases, so that the aim of regulating and controlling the maximum combustion pressure is fulfilled. The support pad 4 is a round pad made of copper and graphite powder, and plays a role in downward heat transfer and friction reduction. The oil distributing pipe 5 of the piston sequentially passes through an oil distributing ring groove on one side of the lower piston body to connect the lower piston body 9, the piston rod 11, the piston cover 2 and the central oil pipe 12 into a whole in series and is lapped on the other side of the lower piston body. The above-described assembly forms a lubricating oil passage and a cooling oil passage inside the piston, respectively, in a combined assembled state as shown in fig. 1, together with the oil distribution ring 19 and the upper and lower combined air rings 21 and 18. The oil, which performs both lubrication and cooling functions, is introduced into the composite piston 1 from the center oil pipe 12 and then divided into several paths by the oil distribution pipes 15. One path enters a lubricating oil channel, engine oil enters an oil distribution ring channel 20 at the back of the oil distribution ring from an oil inlet 17 of the oil distribution ring channel, the oil distribution ring 19 is supplied with oil and distributed with oil in the process of flowing to an oil return hole 8 of the oil distribution ring channel, and the oil distribution ring 19 directly forms a working oil film for ensuring the normal work of the piston assembly between the piston and the cylinder wall through the reciprocating operation of the piston. The redundant engine oil flows into an annular cooling oil cavity 10 through an oil distribution annular oil return hole 8 and becomes a part of the total engine oil for cooling the piston. For a horizontal engine, the oil inlet 17 and the oil return 8 of the oil distribution ring are generally arranged at two ends in the diameter direction, and the oil inlet 17 is arranged in the lower end direction perpendicular to the ground. The engine oil entering the annular cooling oil cavity 10 enters through the oil inlet hole 16 of the annular cooling oil cavity in addition to the oil return of the lubricating oil path, the engine oil in the annular cooling oil cavity 10 cools the upper and lower piston bodies and the piston ring area, and then returns through the oil return slot hole 22 of the annular cooling oil cavity shown in fig. 3, wherein a part of the returned oil enters the cooling oil cavity 23 arranged in the piston cover 2 to cool the piston cover 2. Finally, the entire return oil flows back to the crankcase via the annular return channel 14 between the central oil pipe 12 and the piston rod 11. For the piston cover with the central cone, the working temperature is high because the piston cover is positioned in the center of the piston; meanwhile, for the mobile engine, because the piston does not work in a horizontal position, a cooling oil path can be specially designed according to fig. 4, and oil is injected through the nozzle 24 to cool the cone from the inner cavity of the piston cover 2. The direction of the oil flow is indicated by an oil flow indicator 13. In view of the fact that the working medium always leaks during the operation of the piston group, and the leakage amount is larger after the running-in period and the air sealing ring are greatly worn, in order to ensure the oil distributing and controlling effect of the oil distributing ring and prevent the engine oil from being polluted or foamed, a radial air overflow hole 7 is drilled on the ring land between the oil distributing ring 19 and the upper and lower combined air rings 21 and 18 and is communicated with an axial air overflow hole 6 which leads to the top of the piston upper body 5.