Multi-link power transmission with instantaneous variable compression ratio

Abstract

The multi-link power transmission device with instantaneous variable compression ratio includes a piston, the piston is connected to one end of an upper connecting rod through a piston pin, the other end of the upper connecting rod is hinged to one end of a lower connecting rod through a first hinge shaft, and the other end of the lower connecting rod is connected to a crank of a crankshaft through a crank pin, and the crankshaft is arranged on one side of the piston movement center line L. The positive effects of the present invention are: on the one hand, the thermal efficiency of the engine is improved; on the other hand, the maximum combustion pressure in the engine cylinder is limited by the variable pressure ratio seat and the elastic member, so as to prevent the pressure in the engine cylinder from exceeding the set safety pressure, so that the engine maintains a high compression ratio under low load conditions, and further improves the thermal efficiency of the engine; the variable pressure ratio seat and the elastic member instantly absorb and store the excessive pressure in the cylinder to prevent detonation in the cylinder, and actively release the stored pressure after the pressure in the cylinder drops, and convert it into kinetic energy to assist the piston to move downward, further improving the thermal efficiency of the engine.

Description

Technical Field

[0001] The invention relates to a power transmission device, in particular to a multi-link power transmission device with instantaneous variable compression ratio. Background Art

[0002] When designing the geometric compression ratio of traditional automotive engines, especially automotive gasoline engines, it is generally considered that the engine is suitable for large load output without explosion and has high thermal efficiency. When the vehicle is running normally and the load power is not large, the engine intake volume is small, and the actual compression ratio is less than the geometric compression ratio, so the engine thermal efficiency is lower than the design value. In recent years, in order to solve the knocking problem and improve the thermal efficiency of the engine, the usual technical solution is to use a variable compression ratio so that the engine has a higher compression ratio under low load conditions, and can control the excessive cylinder gas pressure by adjusting the compression ratio under high load conditions to prevent knocking and improve thermal efficiency. However, the variable compression ratio is based on the compression ratio control of the engine working condition, which cannot eliminate the explosion phenomenon caused by the sudden increase of cylinder pressure under low load conditions; it is more likely to further reduce the cylinder pressure of the low pressure cycle under high load conditions, resulting in a decrease in power and economy. There are many solutions for variable compression ratio technology, but it usually requires the use of complex electronic control technology and complex mechanical or hydraulic devices, which are difficult to manufacture and have high production costs. Moreover, due to the slow change of compression ratio, it cannot respond in time when the engine cycle conditions of automobiles and other engines change, and it is impossible to prevent the cylinder pressure from rising instantly. Therefore, in order to avoid the occurrence of knocking, the technical personnel in this field still set the working pressure of the internal combustion engine conservatively. Taking the gasoline engine used in a family car as an example, the normal working pressure of the engine is usually set to about 60% of the pressure when knocking begins, so as to effectively avoid the cylinder pressure from rising instantly and causing knocking under the influence of factors such as vehicle load changes, fuel quality, and intake air temperature and pressure. This obviously limits the improvement of the compression ratio of the existing engine, making it difficult to further improve the thermal efficiency of the existing engine. In order to further solve the above problems, the applicant has designed a technical solution for realizing pressure stabilization and energy storage using the engine piston, and obtained the invention patent authorization, and the authorization announcement number is CN111396199B. This technology can stabilize the pressure in the cylinder of the piston engine by improving the structure of the engine piston, avoid a sharp rise in the pressure in the engine cylinder, and make the cylinder pressure of the engine close to the knocking pressure, but will not cause knocking, so that the thermal efficiency of the piston engine is significantly improved. However, in actual use, the applicant found that although this technology can effectively prevent engine knock and significantly improve engine thermal efficiency, it is limited by the current material strength and processing technology. The cost of processing a piston that meets the strength and sealing requirements is relatively high, and the engine cylinder block needs to be disassembled regularly for maintenance of the piston. Summary of the invention

[0003] The purpose of the present invention is to provide a multi-link power transmission device with instantaneous variable compression ratio, which adopts a multi-link transmission structure, and its crankshaft is arranged with a negative offset at one side of the piston running center line, and a variable pressure ratio seat and an elastic member are provided. On the one hand, the dimensionless torque (arm coefficient) of the crankshaft is increased by the multi-link crankshaft negative offset structure, thereby improving the thermal efficiency of the engine; on the other hand, the maximum combustion pressure in the engine cylinder is limited by the variable pressure ratio seat and the elastic member, so as to prevent the pressure in the engine cylinder from exceeding the set safety pressure, so that the engine maintains a high compression ratio under low load conditions, thereby further improving the thermal efficiency of the engine; when the load suddenly increases, the variable pressure ratio seat and the elastic member instantly absorb and store the excessive pressure in the cylinder, thereby preventing the cylinder from generating knocking, and actively releasing the stored pressure after the pressure in the cylinder drops, and converting it into kinetic energy to assist the piston downward, thereby further improving the thermal efficiency of the engine. Compared with the previous piston-type pressure-stabilizing energy storage technology, the present invention does not require seals to store energy, and the pressure-stabilizing energy storage components are located outside the cylinder body, away from the high-temperature area of ​​fuel combustion, thereby effectively reducing the requirements for material strength and processing precision, the cost is relatively low, and there is no need to disassemble the engine cylinder body for maintenance.

[0004] The technical solution adopted by the present invention to solve the above technical problems is: comprising a piston, the piston is connected to one end of an upper connecting rod through a piston pin, the other end of the upper connecting rod is hinged to one end of a lower connecting rod through a first hinge shaft, the other end of the lower connecting rod is connected to a crank of a crankshaft through a crank pin, and the crankshaft is arranged on one side of a piston motion center line L;

[0005] A third hinge shaft is provided on the lower connecting rod, the third hinge shaft is hinged to one end of the rocker, and the other end of the rocker is hinged to the transformer ratio seat through a fourth hinge shaft; the fourth hinge shaft and the crankshaft are located on the same side of the piston movement center line L, the transformer ratio seat is in contact with the elastic member and the limit seat, the elastic member makes the transformer ratio seat close to the limit seat through elastic pressure or tension, when the transformer ratio seat overcomes the elastic pressure or tension of the elastic member and leaves the limit seat, the distance between the fourth hinge shaft on the transformer ratio seat and the piston movement center line L will be shortened;

[0006] During the piston compression stroke, the crank pin is closer to the piston motion center line L, and during the piston power stroke, the crank pin is farther from the piston motion center line L;

[0007] During the compression stroke of the piston, the angle through which the crankshaft crank rotates is greater than the angle through which the crankshaft crank rotates during the power stroke of the piston.

[0008] One end of the transformer ratio seat is hinged to the articulated seat through the fifth articulated shaft, and one side of the other end of the transformer ratio seat is connected to the spring seat through a spring, and a limit seat is provided on the side of the transformer ratio seat opposite to the spring. A position adjustment device is provided on the transformer ratio seat, and the position adjustment device can adjust the position of the transformer ratio seat when the transformer ratio seat contacts the limit seat, thereby adjusting the distance between the fourth articulated shaft and the center line L of the piston movement. The position adjustment device includes a fifth articulated shaft provided at one end of the transformer ratio seat, and an eccentric shaft is eccentrically provided on the fifth articulated shaft, and the eccentric shaft cooperates with the articulated seat. When the eccentric shaft rotates in the articulated seat, the distance between the fourth articulated shaft on the transformer ratio seat and the center line L of the piston movement will change accordingly. One end of the eccentric shaft passes through the housing of the power transmission device and is provided with an adjustment square column. The spring seat includes a buckle cover installed on the transmission device housing, an adjustment plate is installed in the buckle cover, the spring is located between the adjustment plate and the transformer ratio seat, an adjustment screw is installed on the adjustment plate, the adjustment screw passes through the upper end of the buckle cover, and the inner circumference of the buckle cover is provided with a thread matching the adjustment screw. The pre-tightening pressure of the spring on the transformer ratio seat can be adjusted by rotating the adjustment screw. The transformer ratio seat is provided with a baffle plate and a guide plate perpendicular to each other at one end close to the limit seat, wherein the baffle plate is located between the upper side of the limit seat and the bottom of the spring, and the guide plate is located between one side of the limit seat and the housing of the power transmission device. An elastic buffer pad is provided on the side of the limit seat close to the transformer ratio seat.

[0009] The positive effects of the present invention are: on the one hand, the dimensionless torque (lever coefficient) of the crankshaft is increased through the multi-link crankshaft negative offset structure, thereby improving the thermal efficiency of the engine; on the other hand, the maximum combustion pressure in the engine cylinder is limited through the transformer ratio seat and the elastic member, so as to prevent the pressure in the engine cylinder from exceeding the set safety pressure, so that the engine maintains a high compression ratio under low-load conditions, and further improves the thermal efficiency of the engine; when the load suddenly increases, the transformer ratio seat and the elastic member instantly absorb and store the excessive pressure in the cylinder to prevent detonation in the cylinder, and actively release the stored pressure after the pressure in the cylinder drops, and convert it into kinetic energy to assist the piston to move downward, thereby further improving the thermal efficiency of the engine; compared with the previous piston-type pressure-stabilizing energy storage technology, the present invention does not need to set a seal to store energy, and the pressure-stabilizing energy storage component is located outside the cylinder body, away from the high-temperature area of ​​fuel combustion, thereby effectively reducing the requirements for material strength and processing precision, the cost is relatively low, and there is no need to disassemble the engine cylinder body for maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is one of the structural schematic diagrams of the present invention, showing a state in which the transformer ratio seat is in contact with the limit seat, the fifth articulated shaft is offset downward relative to the eccentric shaft, and the piston reaches the top dead center;

[0011] Figure 2This is the second structural schematic diagram of the present invention, which shows a state where the transformer ratio seat leaves the limit seat, the fifth articulated shaft deviates downward relative to the eccentric shaft, and the piston reaches the top dead center;

[0012] Figure 3 1 is a curve diagram of the force arm coefficient of the present invention, in which the solid line represents the force arm coefficient curve when the transformer ratio seat contacts the limit seat, and the dotted line represents the force arm coefficient curve when the transformer ratio seat instantly leaves the limit seat;

[0013] Figure 4 This is the third structural schematic diagram of the present invention, which shows a state in which the transformer ratio seat is in contact with the limit seat, the fifth articulated shaft is offset upward relative to the eccentric shaft, and the piston reaches the top dead center;

[0014] Figure 5 It is one of the structural schematic diagrams of a single-cylinder engine using the multi-link power transmission device of the present invention;

[0015] Figure 6 is a second structural schematic diagram of a single-cylinder engine using the multi-link power transmission device of the present invention;

[0016] Figure 7 yes Figure 6 A right view structural diagram of ;

[0017] Figure 8 yes Figure 6 A rear view structural diagram of ;

[0018] Fig. 9 yes Figure 6 A schematic diagram of the internal structure of a single-cylinder engine using the multi-link power transmission device of the present invention is shown;

[0019] Fig.10 yes Fig. 9 In the structure shown, the transformer ratio seat is partially interrupted;

[0020] Fig.11 yes Figure 6 Middle AA section enlarged structural diagram;

[0021] Fig.12 yes Fig. 9 Middle BB cross-section enlarged structural diagram. DETAILED DESCRIPTION

[0022] The instantaneous variable compression ratio multi-link power transmission device of the present invention comprises a piston 1, the piston 1 is connected to one end of an upper connecting rod 3 through a piston pin 2, the other end of the upper connecting rod 3 is hinged to one end of a lower connecting rod 5 through a first hinge shaft 4, the other end of the lower connecting rod 5 is connected to a crank of a crankshaft 7 through a crank pin 6, and the crankshaft 7 is arranged on one side of a piston motion center line L;

[0023] A third hinge shaft 8 is provided on the lower connecting rod 5, and the third hinge shaft 8 is hinged to one end of the rocking lever 9, and the other end of the rocking lever 9 is hinged to the transformer ratio seat 11 through a fourth hinge shaft 10; the fourth hinge shaft 10 and the crankshaft 7 are located on the same side of the piston movement center line L, and the transformer ratio seat 11 is in contact with the elastic member and the limit seat 13, and the elastic member makes the transformer ratio seat 11 close to the limit seat 13 through elastic pressure or tension, and when the transformer ratio seat 11 overcomes the elastic pressure or tension of the elastic member and leaves the limit seat 13, the distance between the fourth hinge shaft 10 on the transformer ratio seat 11 and the piston movement center line L will be shortened;

[0024] During the compression stroke of the piston 1, the crank pin (6) is closer to the piston motion center line L, and during the power stroke of the piston 1, the crank pin (6) is farther from the piston motion center line L;

[0025] During the compression stroke of the piston 1 , the angle through which the crank of the crankshaft 7 rotates is greater than the angle through which the crank of the crankshaft 7 rotates during the power stroke of the piston 1 .

[0026] When the piston 1 of the present invention moves back and forth, due to the use of a multi-link crankshaft negative offset structure, that is, the compression stroke occupies a crankshaft angle greater than 180°, and the power stroke occupies a crankshaft angle less than 180°, the piston force is greatly improved to be converted into dimensionless torque of the crankshaft, and the crankshaft angle when the maximum dimensionless torque value is generated is closer to the top dead center. The use of a multi-link transmission structure reduces the deviation angle between the upper connecting rod and the cylinder axis during piston movement, especially the deviation angle of the power stroke stage with a large cylinder explosion pressure is smaller, so that the friction power consumption generated by the side pressure between the piston and the cylinder is reduced to a very small level. The crankshaft rotates at a constant speed and the power stroke is faster than the compression stroke. From the kinematic and dynamic analysis of the well-known traditional single crankshaft connecting rod mechanism, it is concluded that the dimensionless tangential force acting on the crank pin is completely consistent with the dimensionless speed of the piston in terms of magnitude and sign. The piston moves fast in the power stroke and its dimensionless speed is high, which means that the dimensionless tangential force is large; the fast power stroke movement speed also means that the cylinder block and cylinder head maintain high temperature for a short time during the power stroke combustion, which results in less heat dissipation and less heat loss. The fast power stroke movement speed means that the fast combustion expansion speed can reduce the tendency of deflagration and increase the engine compression ratio. This improves the effective thermal efficiency of the engine.

[0027] The elastic pressure or tension applied by the elastic member on the transformer ratio seat 11 of the present invention is pre-set to be slightly lower than the component force acting on the transformer ratio seat 11 through the upper connecting rod 3 when the piston 1 detonates. When the component force acting on the transformer ratio seat 11 through the upper connecting rod 3 of the piston reaches the critical point of deformation of the elastic member, the pressure in the engine cylinder at this time is the preset safety pressure of the present invention, and the safety pressure should be slightly lower than the critical pressure of the fuel detonation in the engine cylinder. The transformer ratio seat 11 and the elastic member can limit the maximum combustion pressure in the engine cylinder, prevent the pressure in the engine cylinder from exceeding the set safety pressure, so that the pressure in the cylinder can be as close as possible to the pressure value that causes detonation when the engine is under low load conditions. In this state, the compression ratio of the engine is significantly higher than that of the existing engine that adjusts the compression ratio by driving the actuator through the electronic control unit, and can maintain the high efficiency of the engine.

[0028] When the engine load suddenly increases, causing the cylinder pressure to exceed the safety pressure and to reach the detonation pressure, the force of the piston 1 acting on the transformer ratio seat 11 through the upper connecting rod 3 exceeds the preset elastic pressure or tension of the elastic member, and the elastic member is deformed. Figure 2 As shown, the transformer seat 11 overcomes the elastic pressure or pulling force of the elastic member and leaves the limit seat 13, and the fourth articulated shaft 10 on the transformer seat 11 approaches the piston movement center line L, so that the piston stops moving upward, the pressure in the cylinder stops rising, and the engine is controlled not to have knock. In this state, the transformer seat 11 and the elastic member instantly absorb and store the excessive pressure in the cylinder to prevent knocking in the cylinder. When the piston starts to move downward and the pressure in the cylinder drops, the elastic member automatically resets, actively releases the stored pressure, and converts its elastic force into kinetic energy to assist the piston in moving downward, thereby further improving the thermal efficiency of the engine.

[0029] In addition, when the transformer ratio seat 11 leaves the limit seat 13, the distance between the piston top dead center and the top position of the combustion chamber becomes larger, and the lower connecting rod 5 swings a certain angle in the opposite direction of the crankshaft 7. When the piston moves downward in the next step, the lower connecting rod 5 drives the crankshaft 7 to rotate at a new transmission angle. Compared with the angle of the lower connecting rod 5 at the piston top dead center when the transformer ratio seat 11 does not leave the limit seat 13, the new transmission angle is larger, so that the force arm coefficient becomes larger at this time. Figure 3 As shown, the solid line represents the arm coefficient curve when the transformer ratio seat is not in action, and the dotted line represents the arm coefficient curve when the transformer ratio seat instantly leaves the limit seat. It can be seen that when the transformer ratio seat 11 leaves the limit seat 13, the arm coefficient of the power transmission device increases, and the thermal efficiency of the engine can be further improved.

[0030] The elastic member of the present invention can adopt a variety of elastic structures such as springs, tension springs, gas springs, elastic steel plates, etc., among which springs are preferably adopted. When the elastic member adopts a spring, the connection relationship between the spring and the transformer ratio seat is as follows: one end of the transformer ratio seat 11 is hinged to the hinge seat 15 through the fifth hinge shaft 14, one side of the other end of the transformer ratio seat 11 is connected to the spring seat 17 through the spring 16, and a limit seat 13 is provided on the side of the transformer ratio seat 11 opposite to the spring 16. The structure of the spring and the transformer ratio seat has the advantages of small size, short energy storage and release stroke, fast response speed, etc.

[0031] In order to adjust the compression ratio of the base of the power transmission device, the present invention may provide a position adjustment device on the transformer ratio seat 11. The position adjustment device can adjust the position of the transformer ratio seat 11 when the transformer ratio seat 11 contacts the limit seat 13, thereby adjusting the distance between the fourth articulated shaft 10 and the center line L of the piston movement. When the distance between the fourth articulated shaft 10 and the center line L of the piston movement decreases, the compression ratio of the base of the power transmission device will decrease accordingly. When the distance between the fourth articulated shaft 10 and the center line L of the piston movement increases, the compression ratio of the base of the power transmission device will increase accordingly. By changing the compression ratio of the base of the power transmission device, the engine equipped with the power transmission device can be made to have a wider range of applicable fuels, so that the engine can achieve normal operation by changing the basic compression ratio when using various fuels such as gasoline, diesel, methanol, etc. of different grades. Figure 4 and Figure 1 By comparison, it can be seen that when Figure 1 In the state shown, that is, when the fifth articulated shaft is offset downward relative to the eccentric shaft, the distance between the piston and the top of the combustion chamber is the smallest, and the basic compression ratio of the engine is the largest at this time; Figure 4 In the state shown, that is, when the fifth articulated shaft is offset upward relative to the eccentric shaft, the distance between the piston and the top of the combustion chamber is the farthest, and the basic compression ratio of the engine is the smallest at this time. According to the combustion characteristics of the fuel added to the engine, the basic compression ratio of the engine can be flexibly adjusted.

[0032] The position adjustment device of the transformer ratio seat 11 of the present invention can adopt a variety of structures, for example, a screw and a matching nut can be installed in the housing of the transmission device, the nut can be fixed on the transformer ratio seat 11, and the position of the transformer ratio seat 11 can be changed by rotating the screw. Among them, the preferred structure is: the position adjustment device includes a fifth hinge shaft 14 arranged at one end of the transformer ratio seat 11, and an eccentric shaft 18 is eccentrically arranged on the fifth hinge shaft 14. The eccentric shaft 18 cooperates with the shaft hole. When the eccentric shaft 18 rotates in the shaft hole, the distance between the fourth hinge shaft 10 on the transformer ratio seat 11 and the piston movement center line L will change accordingly. Compared with other structures, this preferred structure hardly occupies the internal space of the engine, and a larger adjustment range can be achieved with a very small volume. In the above scheme, in order to facilitate the rotation of the eccentric shaft 18, one end of the eccentric shaft 18 can be passed through the housing of the power transmission device and an adjustment square column 19 can be set. The adjustment square column 19 can also be a hexagonal prism, a polygonal prism, or other shapes that are convenient for rotating using tools. The eccentric shaft 18 can also be placed in the housing of the power transmission device, and the rotation angle can be controlled by an electric or hydraulic drive device to adapt to the basic compression ratio required by the fuel added to the engine.

[0033] In order to adjust the elastic force of the spring 16 and thus adjust the preset safety pressure of the power transmission device, the present invention can set an adjusting screw 22 on the spring seat 17. The specific structure is as follows: the spring seat 17 includes a buckle cover 20 installed on the transmission device housing, an adjusting pressure plate 21 is installed in the buckle cover 20, the spring 16 is located between the adjusting pressure plate 21 and the transformer ratio seat 11, and an adjusting screw 22 is installed on the adjusting pressure plate 21. The adjusting screw 22 passes through the upper end of the buckle cover 20, and the inner circumference of the buckle cover 20 is provided with a thread matching the adjusting screw 22. The rotating adjusting screw 22 can adjust the pre-tightening pressure of the spring 16 on the transformer ratio seat 11. When the safety pressure of the power transmission device needs to be adjusted, the adjusting pressure plate 21 can be driven to rise and fall by rotating the adjusting spring 16, thereby changing the compression length of the spring 16, changing the compression elastic force of the spring 16, and then changing the preset safety pressure.

[0034] The transformer ratio seat 11 of the present invention is installed inside the shell of the power transmission device, and its movement direction can be limited by the shell, or an independent guide device can be provided. In order to prevent the transformer ratio seat 11 from being unable to reset normally after moving, a baffle 23 and a guide plate 24 can be provided at one end of the transformer ratio seat 11 close to the limit seat 13, wherein the baffle 23 is located between the upper side of the limit seat 13 and the bottom of the spring 16, and the guide plate 24 is located between one side of the limit seat 13 and the shell of the power transmission device. In this structure, the two sides of the guide plate 24 cooperate with the limit seat 13 and the shell of the power transmission device respectively, and the transformer ratio seat 11 is guided by the limit seat 13 and the shell of the power transmission device. When the transformer ratio seat 11 overcomes the spring elastic force and leaves the limit seat 13, the guide plate 24 is still located between the limit seat 13 and the shell of the power transmission device, so as to prevent the transformer ratio seat 11 from being misaligned with the limit seat and unable to reset.

[0035] In order to alleviate the impact of the transformer ratio seat 11 on the limit seat 13 when it is quickly reset, the present invention can set an elastic buffer pad 12 on the side of the limit seat 13 close to the transformer ratio seat 11. The elastic buffer pad 12 can be made of various existing elastic materials such as high temperature resistant composite rubber and heat resistant polymer elastic material.

Claims

1. A multi-link power transmission device with instantaneous variable compression ratio, comprising a piston (1), characterized in that: The piston (1) is connected to one end of an upper connecting rod (3) through a piston pin (2), the other end of the upper connecting rod (3) is hinged to one end of a lower connecting rod (5) through a first hinge shaft (4), the other end of the lower connecting rod (5) is connected to a crank of a crankshaft (7) through a crank pin (6), and the crankshaft (7) is arranged on one side of a piston movement center line L; A third hinge shaft (8) is arranged on the lower connecting rod (5), the third hinge shaft (8) is hinged to one end of the rocking rod (9), and the other end of the rocking rod (9) is hinged to the transformer ratio seat (11) through a fourth hinge shaft (10); the fourth hinge shaft (10) and the crankshaft (7) are located on the same side of the piston movement center line L, the transformer ratio seat (11) is in contact with the elastic member and the limit seat (13), and the elastic member causes the transformer ratio seat (11) to be closely attached to the limit seat (13) through elastic pressure or tension, and when the transformer ratio seat (11) overcomes the elastic pressure or tension of the elastic member and leaves the limit seat (13), the distance between the fourth hinge shaft (10) on the transformer ratio seat (11) and the piston movement center line L is shortened; During the compression stroke of the piston (1), the crank pin (6) is closer to the piston movement center line L, and during the power stroke of the piston (1), the crank pin (6) is farther from the piston movement center line L; During the compression stroke of the piston (1), the crank of the crankshaft (7) rotates at a greater angle than the crank of the crankshaft (7) rotates during the power stroke of the piston (1).

2. The multi-link power transmission device with instantaneous variable compression ratio according to claim 1, characterized in that: One end of the transformer ratio seat (11) is hinged to the hinge seat (15) via a fifth hinge shaft (14), one side of the other end of the transformer ratio seat (11) is connected to the spring seat (17) via a spring (16), and a limit seat (13) is provided on the side of the transformer ratio seat (11) opposite to the spring (16).

3. The multi-link power transmission device with instantaneous variable compression ratio according to claim 1 or 2, characterized in that: A position adjustment device is provided on the transformer ratio seat (11), and the position adjustment device can adjust the position of the transformer ratio seat (11) when the transformer ratio seat (11) contacts the limit seat (13), thereby adjusting the distance between the fourth hinge shaft (10) and the piston movement center line L.

4. The multi-link power transmission device with instantaneous variable compression ratio according to claim 3, characterized in that: The position adjustment device comprises a fifth articulated shaft (14) arranged at one end of the transformer ratio seat (11), an eccentric shaft (18) being eccentrically arranged on the fifth articulated shaft (14), the eccentric shaft (18) being matched with the articulated seat (15), and when the eccentric shaft (18) rotates in the articulated seat (15), the distance between the fourth articulated shaft (10) on the transformer ratio seat (11) and the piston movement center line L will change accordingly.

5. The multi-link power transmission device with instantaneous variable compression ratio according to claim 4, characterized in that: One end of the eccentric shaft (18) passes through the housing of the power transmission device and is provided with an adjustment square column (19).

6. The multi-link power transmission device with instantaneous variable compression ratio according to claim 2, characterized in that: The spring seat (17) comprises a buckle cover (20) mounted on the transmission device housing, an adjusting pressure plate (21) is mounted in the buckle cover (20), the spring (16) is located between the adjusting pressure plate (21) and the transformer ratio seat (11), an adjusting screw (22) is mounted on the adjusting pressure plate (21), the adjusting screw (22) passes through the upper end of the buckle cover (20), a thread matching the adjusting screw (22) is arranged on the inner circumference of the buckle cover (20), and the pre-tightening pressure of the spring (16) on the transformer ratio seat (11) can be adjusted by rotating the adjusting screw (22).

7. The multi-link power transmission device with instantaneous variable compression ratio according to claim 2, characterized in that: The transformer ratio seat (11) is provided with a baffle (23) and a guide plate (24) which are perpendicular to each other at one end close to the limit seat (13), wherein the baffle (23) is located between the upper side of the limit seat (13) and the bottom of the spring (16), and the guide plate (24) is located between one side of the limit seat (13) and the housing of the power transmission device.

8. The multi-link power transmission device with instantaneous variable compression ratio according to claim 2, characterized in that: An elastic buffer pad (12) is arranged on one side of the limiting seat (13) close to the transformer ratio seat (11).

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