A free piston linear generator system and control method thereof

Abstract

This article provides a free piston linear generator system and a control method thereof. The generator system includes: a cylinder body, having a first piston chamber, an air inlet, a combustion chamber, an exhaust port and a second piston chamber, the combustion chamber is located between the first piston chamber and the second piston chamber, the air inlet is located between the first piston chamber and the combustion chamber, and the exhaust port is located between the second piston chamber and the combustion chamber; a piston group including a first piston and a second piston, the first piston is movably arranged in the first piston chamber, and the second piston is movably arranged in the second piston chamber; wherein a first reset unit is provided between the first piston and the end of the first piston chamber facing away from the combustion chamber, a second reset unit is provided between the second piston and the end of the second piston chamber facing away from the combustion chamber, and a driving force function mechanism capable of generating an acceleration and deceleration of the second piston is provided between the second piston and the peripheral wall of the second piston chamber. The free piston linear generator system can adjust the gas exchange process to be more reasonable.

Description

Technical Field

[0001] The present invention relates to vehicle technology, and more particularly to a free piston linear generator system and a control method thereof. Background Art

[0002] The free piston linear generator is a new type of range extender suitable for electric vehicles. Compared with the traditional engine plus generator structure, its engine and generator are naturally integrated. Since the free piston linear generator eliminates the crankshaft connecting rod mechanism used in traditional engines, the piston moves freely without being constrained by the mechanical structure. Therefore, the engine has the advantages of simple and compact structure and less energy conversion process. In addition, the free piston linear generator has strong fuel universality and can use different types of fuel.

[0003] One of the difficulties in developing free piston linear generators is to organize the ventilation process reasonably. The reasonable organization of the ventilation process of free piston linear generators can improve the charging efficiency, reduce the swept-out mixture, improve the engine efficiency and reduce emissions. How to reasonably organize the ventilation process of free piston linear generators is a technical problem that technicians in this field have been working hard to solve. Summary of the invention

[0004] In order to solve at least one of the above-mentioned technical problems, the present application provides a free piston linear generator system, whose tissue ventilation process can be adjusted to be more reasonable.

[0005] The present application also provides a control method for a free piston linear generator system.

[0006] A free piston linear generator system provided in an embodiment of the present invention comprises: a cylinder body having a first piston chamber, an air inlet, a combustion chamber, an exhaust port and a second piston chamber, wherein the combustion chamber is located between the first piston chamber and the second piston chamber, the air inlet is located between the first piston chamber and the combustion chamber, and the exhaust port is located between the second piston chamber and the combustion chamber; a piston group comprising a first piston and a second piston, wherein the first piston is movably disposed in the first piston chamber and is configured to open and close the air inlet, and the second piston is movably disposed in the second piston chamber and is configured to open and close the exhaust port; wherein a first reset unit is provided between the first piston and an end of the first piston chamber facing away from the combustion chamber, a second reset unit is provided between the second piston and an end of the second piston chamber facing away from the combustion chamber, and a functional mechanism is provided between the second piston and the peripheral wall of the second piston chamber, wherein the functional mechanism is configured to form a driving force for accelerating and decelerating the second piston.

[0007] In some exemplary embodiments, if the operating frequency of the second piston is lower than the design frequency, then during the process of the first piston and the second piston moving toward each other to close the exhaust port, the functional mechanism is controlled to speed up the second piston so that the second piston closes the exhaust port in advance; if the operating frequency of the second piston is higher than the design frequency, then during the process of the first piston and the second piston moving toward each other to close the exhaust port, the functional mechanism is controlled to slow down the second piston so that the second piston delays closing the exhaust port.

[0008] In some exemplary embodiments, an energy conversion mechanism is provided between the first piston and a peripheral wall of the first piston chamber, and the energy conversion mechanism is configured to convert mechanical energy into electrical energy.

[0009] In some exemplary embodiments, the functional mechanism is further configured to convert mechanical energy into electrical energy.

[0010] In some exemplary embodiments, the functional mechanism and the energy conversion mechanism are both electromagnet mechanisms.

[0011] In some exemplary embodiments, the functional mechanism includes: a second coil, disposed on the peripheral wall of the second piston cavity; and a second iron core, disposed in the second piston cavity and connected to the second piston, and a second reset unit is located between the second iron core and an end of the second piston cavity facing away from the combustion chamber.

[0012] In some exemplary embodiments, the first return unit and the second return unit are air springs.

[0013] In some exemplary embodiments, an axial distance between the intake port and the center of the combustion chamber is greater than an axial distance between the exhaust port and the center of the combustion chamber.

[0014] The control method proposed in an embodiment of the present invention includes: if the operating frequency of the second piston is lower than the design frequency, then in the process of the first piston and the second piston moving toward each other to close the exhaust port, controlling the functional mechanism to increase the speed of the second piston so that the second piston closes the exhaust port in advance.

[0015] In some exemplary embodiments, during the process in which the first piston and the second piston move toward each other to close the exhaust port, the exhaust port is closed later than the intake port.

[0016] The control method proposed in an embodiment of the present invention includes: if the operating frequency of the second piston is higher than the design frequency, then in the process of the first piston and the second piston moving toward each other to close the exhaust port, controlling the functional mechanism to decelerate the second piston so that the second piston delays closing the exhaust port.

[0017] In some exemplary embodiments, during the process in which the first piston and the second piston move toward each other to close the exhaust port, the exhaust port is closed later than the intake port.

[0018] The free piston linear generator system provided by the present application has a simple and compact structure. If the operating frequency of the second piston is lower than the design frequency, the mixed gas will be swept out too much in the process of the first piston and the second piston moving toward each other to close the exhaust port. At this time, the control function mechanism is set to increase the speed of the second piston, so that the second piston closes the exhaust port in advance, shortens the exhaust process, and reduces the escape of fresh air in the combustion chamber; if the operating frequency of the second piston is higher than the design frequency, the exhaust gas will be discharged poorly in the process of the first piston and the second piston moving toward each other to close the exhaust port. At this time, the control function mechanism is set to decelerate the second piston, so that the second piston delays closing the exhaust port, prolongs the exhaust process, and is conducive to sweeping out the exhaust gas.

[0019] Other features and advantages of the present application will be described in the following description, and partly become apparent from the description, or be understood by implementing the present application. Other advantages of the present application can be realized and obtained by the schemes described in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide an understanding of the technical solution of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solution of the present application and do not constitute a limitation on the technical solution of the present application.

[0021] Figure 1 A schematic cross-sectional view of a free piston linear generator system according to some embodiments of the present invention;

[0022] Figure 2 is a displacement time curve diagram of the free piston linear generator system when the operating frequency of the second piston is lower than the design frequency;

[0023] Figure 3 This is the displacement time curve of the free piston linear generator system when the operating frequency of the second piston is higher than the design frequency.

[0024] in, Figure 1 The corresponding relationship between the reference numerals and the component names is as follows:

[0025] 1-intake port, 2-exhaust port, 3-cylinder body, 4-spark plug, 5-first piston, 6-second piston, 7-combustion chamber, 8-first iron core, 9-second iron core, 10-second coil, 11-first coil, 12-air spring. DETAILED DESCRIPTION

[0026] This application describes multiple embodiments, but the description is exemplary rather than restrictive, and in order to make the purpose, technical solution and advantages of the present invention clearer, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments and features in the embodiments of this application can be combined with each other arbitrarily without conflict.

[0027] The free piston linear generator system provided by the embodiment of the present invention is as follows: Figure 1 As shown, it includes: a cylinder body 3, the cylinder body 3 has a first piston chamber, an air inlet 1, a combustion chamber 7, an exhaust port 2 and a second piston chamber, the combustion chamber 7 is located between the first piston chamber and the second piston chamber, the air inlet 1 is located between the first piston chamber and the combustion chamber 7, and the exhaust port 2 is located between the second piston chamber and the combustion chamber 7; a piston group including a first piston 5 and a second piston 6, the first piston 5 is axially movably arranged in the first piston chamber and is arranged to open and close the air inlet 1, the second piston 6 is axially movably arranged in the second piston chamber and is arranged to open and close the exhaust port 2; wherein a first reset unit is arranged between the first piston 5 and an end of the first piston chamber facing away from the combustion chamber 7, a second reset unit is arranged between the second piston 6 and an end of the second piston chamber facing away from the combustion chamber 7, a functional mechanism is arranged between the second piston 6 and the peripheral wall of the second piston chamber, the functional mechanism is arranged to form a driving force for accelerating and decelerating the second piston 6, and the functional mechanism can also be arranged to convert the mechanical energy of the second piston 6 into electrical energy for power generation, and the combustion chamber 7 is provided with a spark plug 4 and a fuel injector and other structures. The axial direction is the axial direction of the cylinder body 3. If the working frequency of the second piston 6 is lower than the design frequency, the control function mechanism speeds up the second piston 6 during the process of the first piston 5 and the second piston 6 moving toward each other to close the exhaust port 2, so that the second piston 6 closes the exhaust port in advance; if the working frequency of the second piston 6 is higher than the design frequency, the control function mechanism slows down the second piston 6 during the process of the first piston 5 and the second piston 6 moving toward each other to close the exhaust port 2, so that the second piston 6 delays closing the exhaust port.

[0028] The second piston 6 is located at the inner dead center on the right side (located at the right end of the combustion chamber) and closes the exhaust port 2, and the first piston 5 is located at the inner dead center on the left side (located at the left end of the combustion chamber) and closes the intake port 1. Figure 2As shown by the solid line in , the combustion chamber 7 is ignited and burned by the spark plug 4, and the high-temperature and high-pressure gas pushes the first piston 5 to the left, and the second piston 6 to expand and work to the right. The exhaust port 2 opens at time a, and the intake port 1 opens at time b (b lags behind a), and then the intake port 1 and the exhaust port 2 are in a state of being opened at the same time, until the first piston 5 moves to the left to the outer stop point on the left, and the second piston 6 moves to the right to the outer stop point on the right. In this process, the functional mechanism converts the mechanical energy of the second piston 6 into electrical energy to generate electricity (opposite movement process). Then, the first piston 5 moves to the right toward the combustion chamber 7 under the action of the first reset unit, and the second piston 6 moves to the left toward the combustion chamber 7 under the action of the second reset unit. When the first piston 5 runs to time c, the first piston 5 closes the intake port 1, and when the second piston 6 runs to time d, the second piston 6 closes the exhaust port 2 (d lags behind c), and finally the first piston 5 moves to the inner stop point on the left, and the second piston 6 moves to the inner stop point on the right (backward movement process).

[0029] At the design frequency, the free piston linear generator has a reasonable ventilation process, with the advantages of high charging efficiency, less swept-out mixture, high engine efficiency, and less emissions.

[0030] In actual use, if the operating frequency of the second piston 6 is lower than the design frequency, too much mixed gas will be swept out during the process of the first piston 5 and the second piston moving towards each other to close the exhaust port 2. At this time, it is configured that the control function mechanism accelerates the second piston 6 (that is, the direction of the driving force is toward the combustion chamber 7, which is the same as the movement direction of the second piston 6) during the process of the first piston 5 and the second piston 6 moving towards each other to close the exhaust port 2, so that the second piston 6 closes the exhaust port 2 in advance (in Figure 2 The time e is closed, and the displacement time curve of the second piston 6 changes to Figure 2 The dotted line in the figure can shorten the exhaust process, reduce the escape of fresh air in the combustion chamber 7, and achieve precise control of the scavenging process.

[0031] In actual use, if the operating frequency of the second piston 6 is higher than the design frequency, the exhaust gas will not be discharged smoothly when the first piston and the second piston move towards each other to close the exhaust port 2. At this time, the control function mechanism is set to decelerate the second piston 6 (that is, the direction of the driving force is opposite to the combustion chamber 7, which is opposite to the movement direction of the second piston 6), so that the second piston 6 delays closing the exhaust port 2 (in Figure 3 The time of the second piston 6 is changed to Figure 3 The dotted line in the figure can prolong the exhaust process, which is beneficial for sweeping out the exhaust gas and can achieve precise control of the scavenging process.

[0032] In some examples, such as Figure 1As shown, an energy conversion mechanism is provided between the first piston 5 and the peripheral wall of the first piston chamber. The energy conversion mechanism is configured to convert the mechanical energy of the first piston 5 into electrical energy. The functional mechanism is configured to convert the mechanical energy of the second piston 6 into electrical energy. The functional mechanism and the energy conversion mechanism jointly generate electricity, so that the power generation efficiency is higher.

[0033] In some embodiments, Figure 1 As shown, the functional mechanism and the energy conversion mechanism are both configured as electromagnet mechanisms.

[0034] It can be, for example Figure 1 As shown, the energy conversion mechanism includes: a first coil 11, which is arranged on the peripheral wall of the first piston cavity; and a first iron core 8, which is arranged in the first piston cavity and connected to the first piston 5, and a first reset unit is located between the first iron core 8 and an end of the first piston cavity facing away from the combustion chamber 7. In order to ensure the service life of the functional mechanism, the first reset unit is configured as an air spring 12.

[0035] It can be, for example Figure 1 As shown, the functional mechanism includes: a second coil 10, which is arranged on the peripheral wall of the second piston cavity; and a second iron core 9, which is arranged in the second piston cavity and connected to the second piston 6, and a second reset unit is located between the second iron core 9 and the end of the second piston cavity facing away from the combustion chamber 7. In order to ensure the service life of the second reset unit, the second reset unit is also configured as an air spring 12.

[0036] In some embodiments, the axial distance between the air intake port 1 and the center of the combustion chamber 7 is greater than the axial distance between the exhaust port 2 and the center of the combustion chamber 7, so that the air intake port 1 opens later than the exhaust port 2 during the forward movement, and the exhaust port 2 closes later than the air intake port 1 during the backward movement.

[0037] The second piston 6 is located at the inner stop point on the right side and closes the exhaust port 2, while the first piston 5 is located at the inner stop point on the left side and closes the intake port 1. The spark plug 4 is used to ignite and burn in the combustion chamber 7, and the high-temperature and high-pressure gas pushes the first piston 5 to the left, and the second piston 6 expands to the right to do work. The exhaust port 2 is opened before the intake port 1, and then the intake port 1 and the exhaust port 2 are in a simultaneous open state until the first piston 5 moves to the left to the outer stop point on the left side, and the second piston 6 moves to the right to the outer stop point on the right side. In this process, the functional mechanism and the energy conversion mechanism convert mechanical energy into electrical energy to generate electricity (opposite motion process). Then, the first piston 5 moves to the right toward the combustion chamber 7 under the action of the first reset unit, and the second piston 6 moves to the left toward the combustion chamber 7 under the action of the second reset unit. The intake port 1 is closed before the exhaust port 2. Finally, the first piston 5 moves to the inner stop point on the left side, and the second piston 6 moves to the inner stop point on the right side (backward motion process).

[0038] The free piston linear generator system can use a conventional three-way catalytic converter to achieve equivalent combustion of exhaust gas.

[0039] The control method proposed in the embodiment of the present invention (not shown in the figure) includes: if the operating frequency of the second piston 6 is lower than the design frequency, then in the process of the first piston 5 and the second piston 6 moving toward each other to close the exhaust port 2, the control function mechanism speeds up the second piston 6 so that the second piston 6 closes the exhaust port 2 in advance, thereby shortening the exhaust process and reducing the escape of fresh air in the combustion chamber 7, so as to achieve precise control of the scavenging process.

[0040] In some embodiments, Figure 2 As shown, during the process in which the first piston 5 and the second piston 6 move toward each other to close the exhaust port 2, the exhaust port 2 is closed later than the intake port 1, so that the scavenging process can be more accurately controlled.

[0041] Among them, Figure 2 As shown, during the process of the first piston 5 and the second piston 6 moving in opposite directions, the exhaust port 2 is opened before the intake port 1 .

[0042] The control method proposed in the embodiment of the present invention (not shown in the figure) includes: if the operating frequency of the second piston 6 is higher than the design frequency, then in the process of the first piston 5 and the second piston 6 moving toward each other to close the exhaust port 2, the control function mechanism decelerates the second piston 6, so that the second piston 6 delays closing the exhaust port 2, thereby prolonging the exhaust process, which is conducive to sweeping out the exhaust gas and can achieve precise control of the scavenging process.

[0043] In some embodiments, Figure 3 As shown, during the process in which the first piston 5 and the second piston 6 move toward each other to close the exhaust port 2, the exhaust port 2 is closed later than the intake port 1, so that the scavenging process can be more accurately controlled.

[0044] Among them, Figure 3 As shown, during the process of the first piston 5 and the second piston 6 moving in opposite directions, the exhaust port 2 is opened before the intake port 1 .

[0045] In summary, the technical solution of the free piston linear generator system provided by the present application has a simple and compact structure. If the operating frequency of the second piston is lower than the design frequency, the mixture will be swept out too much in the process of the first piston and the second piston moving toward each other to close the exhaust port. At this time, the control function mechanism is set to increase the speed of the second piston, so that the second piston closes the exhaust port in advance, shortens the exhaust process, and reduces the escape of fresh air in the combustion chamber; if the operating frequency of the second piston is higher than the design frequency, the exhaust gas will be discharged poorly in the process of the first piston and the second piston moving toward each other to close the exhaust port. At this time, the control function mechanism is set to decelerate the second piston, so that the second piston delays closing the exhaust port, prolongs the exhaust process, and is conducive to sweeping out the exhaust gas.

[0046] In the description of the present invention, it should be noted that the terms "upper", "lower", "one side", "the other side", "one end", "the other end", "side", "relative", "four corners", "periphery", "'mouth'-shaped structure" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred structure has a specific orientation, is constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0047] In the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "connection", "direct connection", "indirect connection", "fixed connection", "installation", and "assembly" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; the terms "installation", "connection", and "fixed connection" can be a direct connection, or an indirect connection through an intermediate medium, or the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0048] Although the embodiments disclosed in the present invention are as above, the contents described are only embodiments adopted to facilitate understanding of the present invention and are not intended to limit the present invention. Any technician in the field to which the present invention belongs can make any modifications and changes in the form and details of implementation without departing from the spirit and scope disclosed in the present invention, but the patent protection scope of the present invention shall still be defined by the attached claims.

Claims

1. A free piston linear generator system, characterized in that: include: A cylinder body, comprising a first piston chamber, an air inlet, a combustion chamber, an exhaust port, and a second piston chamber, wherein the combustion chamber is located between the first piston chamber and the second piston chamber, the air inlet is located between the first piston chamber and the combustion chamber, and the exhaust port is located between the second piston chamber and the combustion chamber; A piston group comprising a first piston and a second piston, wherein the first piston is movably disposed in the first piston chamber and is configured to open and close the air inlet, and the second piston is movably disposed in the second piston chamber and is configured to open and close the air outlet; a first reset unit is disposed between the first piston and an end of the first piston chamber facing away from the combustion chamber, a second reset unit is disposed between the second piston and an end of the second piston chamber facing away from the combustion chamber, and a functional mechanism is disposed between the second piston and a peripheral wall of the second piston chamber, wherein the functional mechanism is configured to generate a driving force for accelerating and decelerating the second piston; If the operating frequency of the second piston is lower than the design frequency, in the process of the first piston and the second piston moving toward each other to close the exhaust port, the functional mechanism is controlled to increase the speed of the second piston so that the second piston closes the exhaust port in advance; If the operating frequency of the second piston is higher than the design frequency, during the process of the first piston and the second piston moving toward each other to close the exhaust port, the functional mechanism is controlled to decelerate the second piston so that the second piston delays closing the exhaust port.

2. The free piston linear generator system according to claim 1, characterized in that: An energy conversion mechanism is provided between the first piston and the peripheral wall of the first piston chamber, and the energy conversion mechanism is configured to convert mechanical energy into electrical energy, and the functional mechanism is also configured to convert mechanical energy into electrical energy; wherein the functional mechanism and the energy conversion mechanism are both electromagnet mechanisms.

3. The free piston linear generator system according to claim 1 or 2, characterized in that: The functional mechanism comprises: a second coil disposed on a peripheral wall of the second piston chamber; and The second iron core is disposed in the second piston cavity and connected to the second piston. The second reset unit is located between the second iron core and an end of the second piston cavity facing away from the combustion chamber.

4. The free piston linear generator system according to claim 1 or 2, characterized in that: The first reset unit and the second reset unit are air springs.

5. The free piston linear generator system according to claim 1 or 2, characterized in that: An axial distance between the intake port and the center of the combustion chamber is greater than an axial distance between the exhaust port and the center of the combustion chamber.

6. A control method for a free piston linear generator system according to any one of claims 1 to 5, characterized in that: include: If the operating frequency of the second piston is lower than the design frequency, in the process of the first piston and the second piston moving toward each other to close the exhaust port, the functional mechanism is controlled to increase the speed of the second piston so that the second piston closes the exhaust port in advance; If the operating frequency of the second piston is higher than the design frequency, during the process of the first piston and the second piston moving toward each other to close the exhaust port, the functional mechanism is controlled to decelerate the second piston so that the second piston delays closing the exhaust port.

7. The control method according to claim 6, characterized in that: During the process in which the first piston and the second piston move toward each other to close the exhaust port, the exhaust port is closed later than the intake port.

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