Free piston engine and free piston generator

Abstract

The invention relates to the technical field of free piston engines, in particular to a free piston engine and a free piston generator. The free piston engine comprises an air cylinder and an engine piston, the engine piston is connected with a piston connecting rod, an air valve is arranged on a cylinder cover of the air cylinder, and a transmission connecting rod mechanism is arranged between the piston connecting rod and the air valve; the piston connecting rod is provided with a pushing part, the transmission connecting rod mechanism is provided with an input end and an output end, the input end is used for being matched with the pushing part in a pushing mode, the output end is connected with the air valve, and when the piston connecting rod moves to a set position in the direction away from the cylinder cover, the pushing part pushes the input end to drive the air valve to be opened. The free piston engine further comprises a reset elastic piece which is used for elastically deforming when the input end is matched with the pushing part in a pushing mode and driving the air valve to be closed when the input end is separated from the pushing part in the pushing mode. The driving force of the piston connecting rod and the transmission connecting rod mechanism are matched with the reset elastic piece to control opening and closing of the valve through mechanical structure actions, and cost reduction is facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of free piston engines, and in particular to a free piston engine and a free piston generator. Background Art

[0002] The free piston engine has become a hot topic in the field of internal combustion engines due to its outstanding advantages such as low emissions, high energy efficiency, and wide fuel sources. The free piston engine is a new type of low-carbon power device. It eliminates the crank-connecting rod mechanism, making the movement of the piston unconstrained, so the compression ratio of the engine can be flexibly adjusted. This feature allows the free piston engine to operate under different fuels and achieve HCCI combustion, thereby obtaining higher thermal efficiency and ultra-low pollutant emissions. The free piston engine coupled with a linear generator is a free piston generator, which can directly output electrical energy to the outside with high energy conversion efficiency. It has broad application prospects in the fields of hybrid vehicles, surface and underwater ships, etc.

[0003] Free piston generators are available in single-cylinder and dual-cylinder forms. The basic structure of a single-cylinder free piston generator can be found in a single-cylinder free piston internal combustion power generation system disclosed in a Chinese invention patent application with application publication number CN115355086A and application publication date November 18, 2022. The basic structure of a dual-cylinder free piston generator can be found in a free piston generator system disclosed in a Chinese invention patent application with application publication number CN104653288A and application publication date May 27, 2015. The free piston engine of a free piston generator generally includes a cylinder, a piston is provided in the cylinder, the piston is connected to a piston connecting rod, the piston connecting rod is fixed to the mover of a linear motor, a combustion chamber is provided in the cylinder on the side of the piston facing away from the piston connecting rod, an intake valve and an exhaust valve are provided on the cylinder head of the cylinder, and the intake valve and the exhaust valve are respectively connected to corresponding intake and exhaust ducts, so that when the intake valve is opened, air enters the cylinder through the intake duct, and when the exhaust valve is opened, exhaust gas is discharged from the cylinder through the exhaust duct. The existing intake valves and exhaust valves are opened and closed by electronic control, which requires a corresponding electronic control system, has a complex structure and high cost, and is not well adapted to some products with low performance requirements. Summary of the invention

[0004] The object of the present invention is to provide a free piston engine to solve the problem that the current free piston engine has a high cost due to the electronic control of the intake valve and the exhaust valve; the object of the present invention is also to provide a free piston generator to solve the above problem.

[0005] The technical solution of the free piston engine of the present invention is:

[0006] A free piston engine comprises a cylinder, in which an engine piston is arranged, the engine piston is connected to a piston connecting rod, a valve is arranged on a cylinder head of the cylinder, a transmission connecting rod mechanism is arranged between the piston connecting rod and the valve, a push portion is arranged on the piston connecting rod, the transmission connecting rod mechanism has an input end and an output end, the input end is used for pushing with the push portion, and the output end is connected with the valve, so that when the piston connecting rod moves in a direction away from the cylinder head to a set position, the push portion pushes the input end and drives the valve to open through the transmission connecting rod mechanism, the free piston engine also comprises a reset elastic member for elastically deforming when the input end is pushing with the push portion, and driving the valve to close when the input end is out of pushing with the push portion.

[0007] Beneficial effect: By arranging a transmission connecting rod mechanism between the piston connecting rod and the valve, when the engine piston moves away from the cylinder head, the piston connecting rod moves accordingly, and when moving to the set position, forms a push fit with the input end of the transmission connecting rod mechanism, thereby generating a driving force for the transmission connecting rod mechanism, and then the output end of the transmission connecting rod mechanism drives the valve to move and open the valve. When the engine piston moves toward the cylinder head, the input end of the transmission connecting rod mechanism will be disengaged from the push fit with the push part of the piston connecting rod, and then the valve can be closed under the action of the reset elastic part. In this way, the driving force of the piston connecting rod and the transmission connecting rod mechanism cooperate with the reset elastic part to control the opening and closing of the valve by mechanical structure action, which is conducive to reducing costs.

[0008] Furthermore, the transmission connecting rod mechanism includes a rotatably mounted input rod and output rod and an intermediate rod connected between the input rod and the output rod, the input end is arranged on the input rod, the output end is arranged on the output rod, and the pushing part is used to push the input rod to rotate and then drive the output rod to rotate through the intermediate rod.

[0009] Beneficial effect: the pushing part of the piston connecting rod pushes the input rod to rotate, the rotation of the input rod is converted into the rotation of the output rod through the intermediate rod, and the rotation of the output rod is converted into the direct movement of the valve, that is, the direct movement of the piston connecting rod is converted into the direct movement of the valve through the transmission connecting rod mechanism, the structure is simple, and the transmission is reliable.

[0010] Further, the pushing portion comprises a pushing surface for pushing cooperation with the input end, and the pushing surface gradually extends away from the piston connecting rod axis in a direction toward the piston.

[0011] Beneficial effect: Using the push surface to drive the input rod to rotate is beneficial to controlling the opening speed of the valve.

[0012] Furthermore, the push portion also includes a retaining surface connected to the push surface, the retaining surface is located on the side of the push surface close to the engine piston, and the retaining surface is used to press fit with the input end when the piston connecting rod moves to keep the valve in an open state.

[0013] Beneficial effect: The valve is kept in an open state by utilizing the retaining surface, and the push-pushing cooperation with the input end is maintained, so that the input end is prevented from being separated from the push-pushing part when the engine piston moves in a direction away from the cylinder head.

[0014] Furthermore, the valves arranged on the cylinder head include an intake valve and an exhaust valve, the transmission connecting rod mechanism corresponding to the intake valve is an intake transmission connecting rod mechanism, the transmission connecting rod mechanism corresponding to the exhaust valve is an exhaust transmission connecting rod mechanism, the pushing surface of the pushing portion corresponding to the intake transmission connecting rod mechanism is an intake pushing surface, the pushing surface of the pushing portion corresponding to the exhaust transmission connecting rod mechanism is an exhaust pushing surface, and the distance between the end of the exhaust pushing surface away from the engine piston and the engine piston is greater than the distance between the end of the intake pushing surface away from the engine piston and the engine piston.

[0015] Beneficial effect: When the piston connecting rod moves away from the cylinder head, the exhaust push surface first forms a push fit with the input end of the corresponding transmission connecting rod mechanism, so that the exhaust valve opens first and the intake valve opens later, which facilitates the exhaust gas discharge.

[0016] Furthermore, the degree of deviation of the exhaust push surface relative to the piston connecting rod axis is greater than the degree of deviation of the intake push surface relative to the piston connecting rod axis.

[0017] Beneficial effect: The exhaust valve can be opened quickly by utilizing the exhaust push surface with a large degree of deviation, which facilitates the exhaust gas to be discharged.

[0018] Furthermore, the valves arranged on the cylinder head include an intake valve and an exhaust valve, the transmission connecting rod mechanism corresponding to the intake valve is an intake transmission connecting rod mechanism, the transmission connecting rod mechanism corresponding to the exhaust valve is an exhaust transmission connecting rod mechanism, the pushing portion corresponding to the intake transmission connecting rod mechanism is an intake pushing portion, and the pushing portion corresponding to the exhaust transmission connecting rod mechanism is an exhaust pushing portion, and the distance between the end of the exhaust pushing portion away from the engine piston and the engine piston is greater than the distance between the end of the intake pushing portion away from the engine piston and the engine piston.

[0019] Beneficial effect: the exhaust push portion can contact the input end before the intake push portion, so that the exhaust valve can be opened first, which is convenient for the exhaust gas to be discharged quickly.

[0020] Furthermore, the valves arranged on the cylinder head include an intake valve and an exhaust valve. The intake port of the cylinder head corresponding to the intake valve is connected to an intake duct, and the intake duct is connected to an air compression device. The air compression device includes a cylinder body and an air compression piston arranged in the cylinder body. The air compression piston is transmission-connected to a piston-connecting rod. An air compression chamber is arranged in the cylinder body, and the air compression chamber has an inlet and an outlet. The intake duct is communicated with the outlet of the air compression chamber. The air compression piston is used to compress the gas in the air compression chamber when the piston-connecting rod moves so as to allow compressed air to enter the cylinder when the intake valve is opened.

[0021] Beneficial effects: The piston connecting rod is used in conjunction with the air compressor to achieve intake pressure boosting, improve engine efficiency, and help reduce costs.

[0022] Furthermore, a lubrication cavity is provided on a side of the engine piston away from the cylinder head, and lubrication oil is provided in the lubrication cavity.

[0023] Beneficial effect: The lubricating oil in the lubrication cavity is in a closed space. The lubricating oil is splashed by the collision between the piston skirt and the lubricating oil. The engine piston is lubricated by splash lubrication, which can achieve full lubrication of the two and greatly improve the service life and reliability of the system.

[0024] The technical solution of the free piston generator of the present invention is:

[0025] A free piston generator comprises a coupled free piston engine and a linear generator, wherein the free piston engine comprises a cylinder, wherein an engine piston is arranged in the cylinder, wherein the engine piston is connected to a piston connecting rod, a valve is arranged on a cylinder head of the cylinder, a transmission connecting rod mechanism is arranged between the piston connecting rod and the valve, a push portion is arranged on the piston connecting rod, the transmission connecting rod mechanism has an input end and an output end, wherein the input end is used for push cooperation with the push portion, and the output end is connected to the valve, so that when the piston connecting rod moves in a direction away from the cylinder head to a set position, the push portion pushes the input end and drives the valve to open through the transmission connecting rod mechanism, and the free piston engine also comprises a reset elastic member which is used for elastically deforming when the input end is push cooperation with the push portion and driving the valve to close when the input end is out of push cooperation with the push portion.

[0026] Beneficial effect: By arranging a transmission connecting rod mechanism between the piston connecting rod and the valve, when the engine piston moves away from the cylinder head, the piston connecting rod moves accordingly, and when moving to the set position, forms a push fit with the input end of the transmission connecting rod mechanism, thereby generating a driving force for the transmission connecting rod mechanism, and then the output end of the transmission connecting rod mechanism drives the valve to move and open the valve. When the engine piston moves toward the cylinder head, the input end of the transmission connecting rod mechanism will be disengaged from the push fit with the push part of the piston connecting rod, and then the valve can be closed under the action of the reset elastic part. In this way, the driving force of the piston connecting rod and the transmission connecting rod mechanism cooperate with the reset elastic part to control the opening and closing of the valve by mechanical structure action, which is conducive to reducing costs.

[0027] Furthermore, the transmission connecting rod mechanism includes a rotatably mounted input rod and output rod and an intermediate rod connected between the input rod and the output rod, the input end is arranged on the input rod, the output end is arranged on the output rod, and the pushing part is used to push the input rod to rotate and then drive the output rod to rotate through the intermediate rod.

[0028] Beneficial effect: the pushing part of the piston connecting rod pushes the input rod to rotate, the rotation of the input rod is converted into the rotation of the output rod through the intermediate rod, and the rotation of the output rod is converted into the direct movement of the valve, that is, the direct movement of the piston connecting rod is converted into the direct movement of the valve through the transmission connecting rod mechanism, the structure is simple, and the transmission is reliable.

[0029] Further, the pushing portion comprises a pushing surface for pushing cooperation with the input end, and the pushing surface gradually extends away from the piston connecting rod axis in a direction toward the piston.

[0030] Beneficial effect: Using the push surface to drive the input rod to rotate is beneficial to controlling the opening speed of the valve.

[0031] Furthermore, the push portion also includes a retaining surface connected to the push surface, the retaining surface is located on the side of the push surface close to the engine piston, and the retaining surface is used to press fit with the input end when the piston connecting rod moves to keep the valve in an open state.

[0032] Beneficial effect: The valve is kept in an open state by utilizing the retaining surface, and the push-pushing cooperation with the input end is maintained, so that the input end is prevented from being separated from the push-pushing part when the engine piston moves in a direction away from the cylinder head.

[0033] Furthermore, the valves arranged on the cylinder head include an intake valve and an exhaust valve, the transmission connecting rod mechanism corresponding to the intake valve is an intake transmission connecting rod mechanism, the transmission connecting rod mechanism corresponding to the exhaust valve is an exhaust transmission connecting rod mechanism, the pushing surface of the pushing portion corresponding to the intake transmission connecting rod mechanism is an intake pushing surface, the pushing surface of the pushing portion corresponding to the exhaust transmission connecting rod mechanism is an exhaust pushing surface, and the distance between the end of the exhaust pushing surface away from the engine piston and the engine piston is greater than the distance between the end of the intake pushing surface away from the engine piston and the engine piston.

[0034] Beneficial effect: When the piston connecting rod moves away from the cylinder head, the exhaust push surface first forms a push fit with the input end of the corresponding transmission connecting rod mechanism, so that the exhaust valve opens first and the intake valve opens later, which facilitates the exhaust gas discharge.

[0035] Furthermore, the degree of deviation of the exhaust push surface relative to the piston connecting rod axis is greater than the degree of deviation of the intake push surface relative to the piston connecting rod axis.

[0036] Beneficial effect: The exhaust valve can be opened quickly by utilizing the exhaust push surface with a large degree of deviation, which facilitates the exhaust gas to be discharged.

[0037] Furthermore, the valves arranged on the cylinder head include an intake valve and an exhaust valve, the transmission connecting rod mechanism corresponding to the intake valve is an intake transmission connecting rod mechanism, the transmission connecting rod mechanism corresponding to the exhaust valve is an exhaust transmission connecting rod mechanism, the pushing portion corresponding to the intake transmission connecting rod mechanism is an intake pushing portion, and the pushing portion corresponding to the exhaust transmission connecting rod mechanism is an exhaust pushing portion, and the distance between the end of the exhaust pushing portion away from the engine piston and the engine piston is greater than the distance between the end of the intake pushing portion away from the engine piston and the engine piston.

[0038] Beneficial effect: the exhaust push portion can contact the input end before the intake push portion, so that the exhaust valve can be opened first, which is convenient for the exhaust gas to be discharged quickly.

[0039] Furthermore, the valves arranged on the cylinder head include an intake valve and an exhaust valve. The intake port of the cylinder head corresponding to the intake valve is connected to an intake duct, and the intake duct is connected to an air compression device. The air compression device includes a cylinder body and an air compression piston arranged in the cylinder body. The air compression piston is transmission-connected to a piston-connecting rod. An air compression chamber is arranged in the cylinder body, and the air compression chamber has an inlet and an outlet. The intake duct is communicated with the outlet of the air compression chamber. The air compression piston is used to compress the gas in the air compression chamber when the piston-connecting rod moves so as to allow compressed air to enter the cylinder when the intake valve is opened.

[0040] Beneficial effects: The piston connecting rod is used in conjunction with the air compressor to achieve intake pressure boosting, improve engine efficiency, and help reduce costs.

[0041] Furthermore, a lubrication cavity is provided on a side of the engine piston away from the cylinder head, and lubrication oil is provided in the lubrication cavity.

[0042] Beneficial effect: The lubricating oil in the lubrication cavity is in a closed space. The lubricating oil is splashed by the collision between the piston skirt and the lubricating oil. The engine piston is lubricated by splash lubrication, which can achieve full lubrication of the two and greatly improve the service life and reliability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of Embodiment 1 of the free piston generator of the present invention;

[0044] Figure 2 for Figure 1 Schematic diagram of the free piston engine working stage;

[0045] Figure 3 for Figure 1 Schematic diagram of the exhaust stage of a free piston engine;

[0046] Figure 4 for Figure 1 Schematic diagram of the intake and scavenging stages of a free piston engine;

[0047] Figure 5for Figure 1 Schematic diagram of the compression stage of a free piston engine;

[0048] Figure 6 for Figure 1 The structural diagram of the wedge-shaped platform in FIG.

[0049] Figure 7 for Figure 1 The valve lift curve diagram of the free piston engine in FIG.

[0050] Figure 8 for Figure 1 The diagram of the generator compression ratio change of the free piston engine when using fuel-added lubricating oil lubrication and splash lubrication.

[0051] In the figure: 1. intake valve; 2. injector; 3. engine cylinder; 4. engine piston; 5. lubrication chamber; 6. piston connecting rod; 7. wedge-shaped platform; 8. intake duct; 9. left pressure chamber; 10. compression piston; 11. right pressure chamber; 12. right chamber outlet check valve; 13. linear motor stator; 14. linear motor mover; 15. right chamber intake check valve; 16. left chamber outlet check valve; 17. left chamber intake check valve; 18. lubricating oil; 19. intake transmission connecting rod mechanism; 20. exhaust transmission connecting rod mechanism; 21. exhaust duct; 22. exhaust valve; 23. spark plug; 24. exhaust slope; 25. intake slope; 26. exhaust slope inclination; 27. intake slope inclination. DETAILED DESCRIPTION

[0052] Embodiment 1 of the free piston generator of the present invention:

[0053] In this embodiment, a transmission connecting rod mechanism is arranged between the piston connecting rod and the valve. When the engine piston moves away from the cylinder head, the piston connecting rod moves accordingly, and when it moves to the set position, it forms a push fit with the input end of the transmission connecting rod mechanism, thereby generating a driving force for the transmission connecting rod mechanism, and then the output end of the transmission connecting rod mechanism drives the valve to move and open the valve. When the engine piston moves toward the cylinder head, the input end of the transmission connecting rod mechanism will disengage from the push fit with the push part of the piston connecting rod, and then the valve can be closed under the action of the reset elastic member. In this way, the driving force of the piston connecting rod and the transmission connecting rod mechanism cooperate with the reset elastic member to control the opening and closing of the valve by mechanical structure action, which is conducive to reducing costs.

[0054] Specifically, Figure 1-8 As shown, the free piston generator in this embodiment is a double-cylinder free piston generator, including two free piston engines arranged on the left and right and a linear motor located between the two free piston engines.

[0055] The free piston engine comprises an engine cylinder 3, an engine piston 4, a piston connecting rod 6, an intake valve 1, an exhaust valve 22, an intake passage 8, an exhaust passage 21, an injector 2, and a spark plug 23. The engine piston 4 is connected to the piston connecting rod 6 as a whole through a piston pin. The engine cylinder 3, the engine piston 4 and the piston connecting rod 6 can reciprocate in the cylinder as a whole. The inner cavity of the engine cylinder 3 is a closed cavity, and the engine piston 4 divides the closed cavity into two chambers. The engine cylinder 3 has a cylinder head, and the chamber between the cylinder head and the engine piston 4 is a combustion chamber. A plugging cover is also provided at one end of the engine cylinder 3 away from the cylinder head, and the chamber between the plugging cover and the piston is a lubrication chamber 5. The lubrication chamber 5 is filled with liquid lubricating oil 18. The lubricating oil 18 is splashed by the reciprocating motion of the engine piston 4, and the splashed lubricating oil 18 adheres to the surface of the engine piston 4 and the engine cylinder 3, thereby achieving full lubrication of the piston and the cylinder.

[0056] The intake valve 1 and the exhaust valve 22 are both arranged on the cylinder head of the engine cylinder 3. The positions of the intake valve 1 and the exhaust valve 22 on the cylinder head are respectively provided with an intake port and an exhaust port. The intake port is connected to the intake passage 8, and the exhaust port is connected to the exhaust passage 21. The corresponding valves are opened and closed by the left and right movements of the intake valve 1 and the exhaust valve 22.

[0057] A transmission connecting rod mechanism is provided between the piston connecting rod 6 and the valve, so as to drive the valve to open and close through the reciprocating motion of the piston connecting rod 6. The transmission connecting rod mechanism corresponding to the intake valve 1 is the intake transmission connecting rod mechanism 19, and the transmission connecting rod mechanism corresponding to the exhaust valve 22 is the exhaust transmission connecting rod mechanism 20. The transmission connecting rod mechanism includes an input rod, an output rod and an intermediate rod. The input rod and the output rod are both rotatably mounted on the corresponding fixed base. A rotating mounting shaft is provided in the middle of the input rod and the output rod. One end of the input rod close to the piston connecting rod 6 constitutes the input end, and the other end is hinged to the intermediate rod. One end of the output rod is hinged to the intermediate rod, and the other end is hinged to the corresponding valve and constitutes the output end. A wedge-shaped platform 7 is fixedly provided on the piston connecting rod 6, and the wedge-shaped platform 7 reciprocates with the piston connecting rod 6. The upper and lower surfaces of the wedge-shaped platform 7 are processed with slopes, the upper slope is the intake slope 25, and the lower slope is the exhaust slope 24. The intake ramp 25 is used to push and cooperate with the input end of the intake transmission connecting rod mechanism 19 to drive the input rod to rotate, the input rod drives the output rod to rotate through the intermediate rod, and the output rod drives the intake valve 1 to open. The exhaust ramp 24 is used to push and cooperate with the input end of the exhaust transmission connecting rod mechanism 20 to drive the input rod to rotate, the input rod drives the output rod to rotate through the intermediate rod, and the output rod drives the exhaust valve 22 to open.

[0058] The slope of the intake ramp 25 constitutes an intake push slope corresponding to the intake transmission connecting rod mechanism 19, and the intake push slope constitutes an intake push surface. The slope of the exhaust ramp 24 constitutes an exhaust push slope corresponding to the exhaust transmission connecting rod mechanism 20, and the exhaust push slope constitutes an exhaust push surface. The upper side surface of the wedge-shaped platform 7 also includes an intake holding plane located on the side of the intake ramp 25 close to the engine piston 4, and the lower side surface of the wedge-shaped platform 7 also includes an exhaust holding plane located on the side of the exhaust ramp 24 close to the engine piston 4. The intake holding plane and the slope of the intake ramp 25 together constitute an intake push portion corresponding to the intake transmission connecting rod mechanism 19, and the exhaust holding plane and the slope of the exhaust ramp 24 together constitute an exhaust push portion corresponding to the exhaust transmission connecting rod mechanism 20. The push portion is used to push the input rod to rotate, so that when the piston connecting rod 6 moves to a set position in a direction away from the cylinder head, the push portion pushes the input end and drives the valve to open through the transmission connecting rod mechanism.

[0059] When the valve is in the closed state, the wedge-shaped platform 7 on the piston connecting rod 6 is located on the side of the input end of the transmission connecting rod mechanism close to the piston and is separated from the input end by a distance. After the piston moves a certain distance, the pushing portion of the wedge-shaped platform 7 starts to push and contact with the input end. The input end contacts before the pushing inclined surface. As the wedge-shaped platform 7 pushes the input rod to rotate, the input rod moves away from the piston connecting rod 6. As the piston connecting rod 6 moves away from the cylinder head, the pushing inclined surface of the wedge-shaped platform 7 passes over the input end, so that the input end is pressed and contacted with the holding plane. The movement stroke of the piston connecting rod 6 satisfies that the holding plane does not completely pass over the input end, that is, the piston dead point position is associated with the position of the wedge-shaped platform 7. The holding plane constitutes a holding surface. The holding plane can press and cooperate with the input end when the piston connecting rod 6 moves to keep the valve open, and the input rod is no longer rotated, thereby ensuring the piston stroke and preventing the input end from being separated from the wedge-shaped platform 7.

[0060] When the engine cylinder 3 ends the power, exhaust, intake and scavenging phases and enters the compression phase, the engine piston 4 moves toward the cylinder head, and when the push slope of the wedge-shaped platform 7 corresponds to the input end, the valve begins to close, the push portion and the input end are separated from the push fit, and the valve is closed. The valve is equipped with a reset elastic member for driving the valve to close when the input end and the push portion are separated from the push fit, and the reset elastic member is arranged between the cylinder and the valve, and the reset elastic member can be a valve spring.

[0061] The distance between the end of the exhaust slope 24 away from the engine piston 4 and the engine piston 4 is greater than the distance between the end of the intake slope 25 away from the engine piston 4 and the engine piston 4, so that when the piston connecting rod 6 moves in the direction away from the cylinder head, the exhaust push slope first forms a push fit with the input end of the exhaust transmission connecting rod mechanism 20, so that the exhaust valve 22 opens first and the intake valve 1 opens later, which is convenient for exhaust gas discharge. The exhaust valve opens before the intake valve and closes later than the intake valve. The push ramp gradually deviates from the piston connecting rod axis and extends in the direction toward the piston. The push ramp is used to drive the input rod to rotate, which is beneficial to controlling the opening speed of the valve through the inclination angle of the ramp. The exhaust ramp inclination angle 26 is greater than the intake ramp inclination angle 27. The exhaust ramp inclination angle 26 is the inclination angle of the exhaust push ramp relative to the piston connecting rod 6 axis, which means that the deviation degree of the exhaust push ramp relative to the piston connecting rod axis is greater than the deviation degree of the intake push ramp relative to the piston connecting rod axis. The larger the inclination angle, the greater the deviation degree. The intake ramp inclination angle 27 is the inclination angle of the intake push ramp relative to the piston connecting rod 6 axis. Using an exhaust push ramp with a larger inclination angle can make the exhaust valve 22 open quickly, which is convenient for exhaust gas discharge. The length of the exhaust slope 24 that controls the opening and closing of the exhaust valve 22 is greater than the slope length of the intake slope 25 that controls the opening and closing of the intake valve 1, and the end of the intake slope 25 close to the engine piston 4 is closer to the engine piston 4 than the end of the exhaust slope 24 close to the engine piston 4, so as to control the opening and closing sequence of the intake valve 1 and the exhaust valve 22.

[0062] The air inlet 8 is connected to a compressor device, which includes a compressor cylinder, a compressor piston 10, and a compressor piston rod. The compressor cylinder constitutes the cylinder body of the compressor device. The compressor piston 10 can move back and forth in the compressor cylinder driven by the compressor piston rod. The compressor piston 10 is connected to the piston connecting rod 6 through the compressor piston rod and moves synchronously with the piston connecting rod 6. The compression piston 10 divides the inner cavity of the compressor cylinder into a left compression chamber 9 and a right compression chamber 11. Both compression chambers are provided with an inlet and an outlet. The inlet of the left compression chamber 9 is provided with a left chamber inlet check valve 17, and the outlet of the left compression chamber 9 is provided with a left chamber outlet check valve 16. The inlet of the right compression chamber 11 is provided with a right chamber inlet check valve 15, and the outlet of the right compression chamber 11 is provided with a right chamber outlet check valve 12. The outlet of the left compression chamber 9 is connected to the air inlet of the right free piston engine through the air inlet 8, and the outlet of the right compression chamber 11 is connected to the air inlet of the left free piston engine through the air inlet 8. The compression piston is fixed to the compressor piston rod. Through the reciprocating motion of the compression piston, the external gas is sucked in and the gas in the compression chamber is pressurized. When the air inlet valve 1 is opened, the compressed air enters the cylinder. The piston connecting rod 6 cooperates with the air compression device to realize the air intake pressurization of the free piston engines on both sides, thereby improving the engine efficiency and helping to reduce the cost.

[0063] The linear motor includes a linear motor stator 13 and a linear motor mover 14. The linear motor mover 14 is fixed to the piston connecting rod 6 of the right free piston engine. The piston connecting rods 6 of the free piston engines on the left and right sides are fixed to the linear motor mover 14 and the compressor piston rod and move synchronously. The linear motor works in the motor mode when the engine is started, and can drive the piston connecting rod 6 to reciprocate. Once the engine is successfully started, the working mode is switched to the generator mode to output electrical energy to the outside.

[0064] The reciprocating motion of the piston connecting rod 6 provides a power source for the wedge-shaped stage 7 to drive the valve and the compressor piston 10 to compress the air. The fuel injector 2 is installed near the intake valve 1 of the intake duct 8. When the intake valve 1 is opened, the fuel is sprayed into the intake duct 8 and mixed with the air to enter the cylinder. The spark plug 23 is installed on the cylinder head at the top of the cylinder. When the engine piston 4 runs to the top dead center, an electric spark is generated to ignite the oil-gas mixture in the cylinder.

[0065] Taking the left engine cylinder 3 as an example, the working process of the overhead valve type two-stroke free piston engine provided by this embodiment is further described:

[0066] like Figure 2 As shown, at the initial stage of engine startup, the linear motor works in the motor mode, and the linear motor mover 14 moves to the right in the horizontal direction under the action of electromagnetic force;

[0067] When the piston connecting rod 6 moves to the right, for the left pressure air chamber 9, the left chamber air inlet check valve 17 opens, the left chamber air outlet check valve 16 closes, and the left pressure air chamber 9 inhales air. For the right pressure air chamber 11, the right chamber air outlet check valve 12 opens, the right chamber air inlet check valve 15 closes, and the gas pressure inside the right pressure air chamber 11 increases. At this time, the exhaust transmission connecting rod mechanism 20 first opens the exhaust valve 22 under the action of the wedge-shaped platform 7, as shown in FIG. Figure 3 As shown in FIG. 1 , as the piston connecting rod 6 continues to move rightward, the intake transmission connecting rod mechanism 19 opens the intake valve 1 again under the action of the wedge-shaped platform 7, and the high-pressure gas in the right pressure chamber 11 enters the engine cylinder 3 along the intake duct 8 and the intake valve 1, as shown in FIG. Figure 4 At the same time, the injector 2 located near the intake valve 1 starts to work, spraying the fuel into the intake passage 8, and entering the engine cylinder 3 together with the gas in the intake passage 8. The above process completes the engine intake stroke;

[0068] The piston connecting rod 6 then starts to move in the opposite direction under the action of the linear motor, pushing the piston connecting rod 6 and the engine piston 4 to move to the left. At this time, the wedge-shaped platform 7 is separated from the intake transmission connecting rod mechanism 19 and the exhaust transmission connecting rod mechanism 20 one after another, and the intake valve 1 and the exhaust valve 22 close the intake port and the exhaust port under the action of the valve spring. Figure 5As shown. The engine piston 4 continues to move to the left to compress the oil-gas mixture in the engine cylinder 3. When the engine piston 4 moves to the vicinity of the top dead center, the spark plug 23 starts to work, sprays sparks, and ignites the high-pressure oil-gas mixture. The burning high-temperature and high-pressure gas pushes the piston connecting rod 6 to move to the right, and the wedge-shaped platform 7 drives the exhaust transmission connecting rod mechanism 20 to first open the exhaust valve 22 for exhaust, and then open the intake valve 1 to complete the intake and scavenging. In this way, the left engine cylinder 3 completes a working cycle. As for the right engine cylinder 3, it follows the same working principle, which will not be repeated here.

[0069] The wedge-shaped stage 7 drives the valve transmission connecting rod mechanism to open the intake valve 1 and the exhaust valve 22 successively. The lift curves of the intake valve 1 and the exhaust valve 22 are as follows: Figure 7 As shown, it can be seen that, unlike the lift curves of the intake and exhaust valves 22 of a conventional internal combustion engine, the lift curve of the intake valve 1 of the two-stroke free piston generator in this embodiment is completely within the lift curve of the exhaust valve 22 .

[0070] Since the lubricating oil 18 in the lubricating chamber 5 is in a closed space, the lubricating oil 18 is splashed by the collision between the piston skirt and the lubricating oil 18, which plays a good lubricating role and prolongs the working time of the engine. Figure 8 As shown, it can be seen that when the fuel mixed lubricant 18 is used for lubrication, the compression ratio of the engine gradually decreases after running for a period of time, so that the engine finally shuts down and stalls; while for the case of splash lubrication, the engine compression ratio remains basically unchanged and can run for a long time, which also verifies the superiority of splash lubrication.

[0071] The free piston engine improves the cylinder charging efficiency and fuel utilization rate during the operation of the engine, improves the engine operation efficiency, ensures the efficient lubrication of parts, and increases the operating life of the generator. By combining the piston connecting rod with the air compressor and reasonably arranging the one-way inlet and exhaust valves on the air compressor, the reciprocating motion of the piston connecting rod is used to help the engine itself achieve intake pressure without the need for any external equipment. The overhead valve design can realize the injection of fuel while scavenging. The fuel can be injected into the intake duct in the later stage of the scavenging process, which reduces the waste of fuel and greatly improves the utilization efficiency of fuel. The quality of lubrication between the cylinder and the piston directly determines the service life and reliability of the free piston generator. In the past, the lubrication of the cylinder piston assembly of the two-stroke free piston generator was mainly achieved by adding a certain proportion of lubricating oil to the injected fuel. The lubricating oil and fuel are injected into the cylinder from the scavenging chamber and through the scavenging duct (that is, the scavenging chamber and the cylinder are connected during the scavenging process) to achieve lubrication of the cylinder piston. However, due to the low lubricating oil content, the lubrication between the cylinder and the piston is insufficient, the cylinder and piston have a short life, and the pollutant content of the combustion products is high. The scavenging chamber of the two-stroke free piston generator with an overhead valve design is a closed lubrication chamber, which can store a large amount of lubricating oil. The cylinder and piston are lubricated by splash lubrication, which can achieve sufficient lubrication of the two, greatly improving the service life and reliability of the system.

[0072] Embodiment 2 of the free piston generator of the present invention:

[0073] This embodiment provides a transmission connecting rod mechanism arrangement form different from that of the embodiment 1. The difference between this embodiment and the embodiment 1 is that the transmission connecting rod mechanism in the embodiment 1 includes a rotatably mounted input rod and an output rod and an intermediate rod connected between the input rod and the output rod. In this embodiment, the transmission connecting rod mechanism is a sliding connecting rod arranged to slide back and forth, and the sliding connecting rod is provided with a guide rail for guiding its sliding, and the pushing portion on the piston connecting rod pushes the sliding connecting rod to translate to open the valve.

[0074] Embodiment 3 of the free piston generator of the present invention:

[0075] This embodiment provides a different arrangement of the push portion from that of the first embodiment. The difference between this embodiment and the first embodiment is that the push portion in the first embodiment includes a push inclined surface for pushing with the input end. In this embodiment, no push inclined surface is provided, and the upper side surface of the push portion is a plane.

[0076] Embodiment 4 of the free piston generator of the present invention:

[0077] This embodiment provides a different arrangement of the push portion from that of the first embodiment. The difference between this embodiment and the first embodiment is that the push portion in the first embodiment further includes a retaining plane connected to the push inclined surface, and the retaining plane is located on the side of the push inclined surface close to the engine piston. In this embodiment, however, no retaining plane is provided, and the length and position of the slope on the wedge-shaped platform meet the requirements of valve opening and closing and do not break away from the push cooperation with the input end.

[0078] Embodiment 5 of the free piston generator of the present invention:

[0079] This embodiment provides a different arrangement of the push portion from that of the first embodiment. The difference between this embodiment and the first embodiment is that the distance between the end of the exhaust push slope away from the engine piston and the engine piston in the first embodiment is greater than the distance between the end of the intake push slope away from the engine piston and the engine piston. In this embodiment, the distance between the end of the exhaust push slope away from the engine piston and the engine piston is equal to the distance between the end of the intake push slope away from the engine piston and the engine piston.

[0080] Embodiment 6 of the free piston generator of the present invention:

[0081] This embodiment provides a different arrangement of the push portion from that of the first embodiment. The difference between this embodiment and the first embodiment is that the inclination angle of the exhaust push slope relative to the piston connecting rod axis in the first embodiment is greater than the inclination angle of the intake push slope relative to the piston connecting rod axis. In this embodiment, the inclination angle of the exhaust push slope relative to the piston connecting rod axis is equal to the inclination angle of the intake push slope relative to the piston connecting rod axis.

[0082] Embodiment 7 of the free piston generator of the present invention:

[0083] This embodiment provides an air intake duct arrangement different from that of embodiment 1. The difference between this embodiment and embodiment 1 is that the air intake duct in embodiment 1 is connected to an air compressor. In this embodiment, no air compressor is provided on the air intake duct, and the air intake duct is directly connected to the outside air.

[0084] Embodiment 8 of the free piston generator of the present invention:

[0085] This embodiment provides a different engine cylinder arrangement from that of the first embodiment. The difference between this embodiment and the first embodiment is that a lubrication cavity is provided on the side of the engine piston away from the cylinder head in the first embodiment, and lubricating oil is provided in the lubrication cavity. In this embodiment, however, no lubrication cavity is provided, and a certain proportion of lubricating oil is still added to the fuel to lubricate the cylinder piston.

[0086] Embodiment 9 of the free piston generator of the present invention:

[0087] This embodiment provides a different arrangement of the push portion from that of the first embodiment. The difference between this embodiment and the first embodiment is that the push surface of the push portion in the first embodiment is a push inclined surface, and the retaining surface is a retaining plane. In this embodiment, the push surface of the push portion is a conical surface, and the retaining surface is a cylindrical surface. Accordingly, the taper of the conical surface represents the degree of deviation of the push surface from the piston connecting rod axis. The greater the taper, the greater the degree of deviation.

[0088] Embodiment of the free piston engine of the present invention:

[0089] The free piston engine in this embodiment is the same as the free piston engine in any of the above-mentioned embodiments 1-9 of the free piston generator, and will not be described in detail here.

[0090] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions recorded in the aforementioned embodiments without creative work, or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A free piston engine, comprising a cylinder, an engine piston is mounted in the cylinder, the engine piston is connected to a piston connecting rod, and a valve is arranged on the cylinder head of the cylinder, wherein: A transmission connecting rod mechanism is provided between the piston connecting rod and the valve, and a push portion is provided on the piston connecting rod. The transmission connecting rod mechanism has an input end and an output end, the input end is used for pushing with the push portion, and the output end is connected with the valve, so that when the piston connecting rod moves in a direction away from the cylinder head to a set position, the push portion pushes the input end and drives the valve to open through the transmission connecting rod mechanism. The free piston engine also includes a reset elastic member for elastically deforming when the input end is pushing with the push portion, and driving the valve to close when the input end is out of pushing with the push portion.

2. The free piston engine according to claim 1, characterized in that: The transmission connecting rod mechanism includes a rotatably mounted input rod and output rod and an intermediate rod connected between the input rod and the output rod. The input end is arranged on the input rod, and the output end is arranged on the output rod. The pushing part is used to push the input rod to rotate and then drive the output rod to rotate through the intermediate rod.

3. The free piston engine according to claim 2, characterized in that: The pushing portion comprises a pushing surface for pushing and cooperating with the input end, and the pushing surface gradually extends away from the axis of the piston connecting rod in a direction toward the piston.

4. The free piston engine according to claim 3, characterized in that: The push portion also includes a retaining surface connected to the push surface, the retaining surface is located on a side of the push surface close to the engine piston, and the retaining surface is used to press fit with the input end when the piston connecting rod moves to keep the valve open.

5. The free piston engine according to claim 3 or 4, characterized in that: The valves arranged on the cylinder head include an intake valve and an exhaust valve, the transmission connecting rod mechanism corresponding to the intake valve is an intake transmission connecting rod mechanism, the transmission connecting rod mechanism corresponding to the exhaust valve is an exhaust transmission connecting rod mechanism, the pushing surface of the pushing portion corresponding to the intake transmission connecting rod mechanism is an intake pushing surface, the pushing surface of the pushing portion corresponding to the exhaust transmission connecting rod mechanism is an exhaust pushing surface, and the distance between the end of the exhaust pushing surface away from the engine piston and the engine piston is greater than the distance between the end of the intake pushing surface away from the engine piston and the engine piston.

6. The free piston engine according to claim 5, characterized in that: The degree of deviation of the exhaust push surface relative to the piston connecting rod axis is greater than the degree of deviation of the intake push surface relative to the piston connecting rod axis.

7. A free piston engine according to claim 1 or 2, characterized in that: The valves arranged on the cylinder head include an intake valve and an exhaust valve, the transmission connecting rod mechanism corresponding to the intake valve is the intake transmission connecting rod mechanism, the transmission connecting rod mechanism corresponding to the exhaust valve is the exhaust transmission connecting rod mechanism, the pushing portion corresponding to the intake transmission connecting rod mechanism is the intake pushing portion, and the pushing portion corresponding to the exhaust transmission connecting rod mechanism is the exhaust pushing portion, and the distance between the end of the exhaust pushing portion away from the engine piston and the engine piston is greater than the distance between the end of the intake pushing portion away from the engine piston and the engine piston.

8. The free piston engine according to claim 1, 2, 3 or 4, characterized in that: The valves arranged on the cylinder head include an intake valve and an exhaust valve. The intake port of the cylinder head corresponding to the intake valve is connected to an intake duct, and the intake duct is connected to an air compression device. The air compression device includes a cylinder body and an air compression piston arranged in the cylinder body. The air compression piston is transmission-connected to a piston connecting rod. An air compression chamber is arranged in the cylinder body, and the air compression chamber has an inlet and an outlet. The intake duct is communicated with the outlet of the air compression chamber. The air compression piston is used for compressing the gas in the air compression chamber when the piston connecting rod moves so as to allow compressed air to enter the cylinder when the intake valve is opened.

9. The free piston engine according to claim 1, 2, 3 or 4, characterized in that: A lubrication cavity is provided on the side of the engine piston away from the cylinder cover, and lubrication oil is provided in the lubrication cavity.

10. A free piston generator, comprising a coupled free piston engine and a linear generator, characterized in that: The free piston engine is a free piston engine as described in any one of claims 1 to 9.

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