Free-piston linear generator system and control method therefor
By controlling the movement of the functional mechanism to the second piston according to the operating frequency in the free piston linear generator system, the problem of poor emission of mixed and exhaust gas during ventilation is solved, and the inflation efficiency and engine efficiency are improved.
Patent Information
- Application Number
- PCT/CN2023/108705
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2023-02-16
- Filing Date
- 2023-07-21
- Publication Date
- 2024-12-12
AI Technical Summary
Free piston linear generators are difficult to achieve reasonable inflation efficiency and exhaust emission control during the ventilation process, resulting in excessive sweep of mixture or poor exhaust emission, affecting engine efficiency and emissions.
By introducing a functional mechanism into the free piston linear generator system, the control function mechanism increases or decreases the second piston when the operating frequency of the second piston is lower than or higher than the design frequency, so that it closes the row in advance or delays. The air port can adjust the ventilation process, shorten or extend the exhaust time, and accurately control the scavenging process.
Achieve higher inflation efficiency, reduce the sweep of mixture and exhaust gas, and improve engine efficiency and emission performance.
Smart Images
Figure CN2023108705_12122024_PF_FP_ABST
Abstract
Description
A free piston linear generator system and control method thereof
[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on February 16, 2023, with application number 202310126846.9 and invention name “A free piston linear generator system and its control method”, the contents of which should be understood as incorporated into this application by reference. Technical Field
[0002] This article relates to but is not limited to vehicle technology, and in particular to a free piston linear generator system and a control method thereof. Background Art
[0003] The free-piston linear generator (FPLG) is a novel range-extending device suitable for electric vehicles. Compared to conventional engine-generator structures, its engine and generator are naturally integrated. Because the FPLG eliminates the crankshaft-connecting rod mechanism used in conventional engines, the piston moves freely without mechanical constraints. This engine offers advantages such as a simple and compact structure and minimal energy conversion processes. Furthermore, the FPLG is fuel-compatible and can operate on a variety of fuels.
[0004] One of the challenges in developing free-piston linear generators is properly organizing the ventilation process. This process can improve charging efficiency, reduce swept-out mixture, increase engine efficiency, and reduce emissions. How to properly organize the ventilation process in free-piston linear generators is a technical challenge that those skilled in the art have been working to address.
[0005] Summary of the Invention
[0006] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.
[0007] The free piston linear generator system provided by the embodiment of the present disclosure 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 is arranged to be able to open and close the air inlet, the second piston is movably arranged in the second piston chamber and is arranged to be able to open and close the exhaust port; 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 functional mechanism is provided between the second piston and the peripheral wall of the second piston chamber, and the functional mechanism is arranged to be able to generate a driving force for accelerating and decelerating the second piston.
[0008] The control method proposed in an embodiment of the present invention includes: when the operating frequency of the second piston is lower than the design frequency, during 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.
[0009] The control method proposed in the embodiment of the present disclosure includes: when 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, controlling the functional mechanism to decelerate the second piston so that the second piston delays closing the exhaust port.
[0010] Other features and advantages of the present application will be described in the following description, and in part will become apparent from the description, or will be understood by practicing the present application. Other advantages of the present application can be realized and obtained through the solutions described in the description and the drawings.
[0011] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.
[0012] Summary of the Figures
[0013] FIG1 is a schematic cross-sectional view of a free piston linear generator system according to some embodiments;
[0014] FIG2 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;
[0015] FIG3 is a displacement time curve diagram of the free piston linear generator system when the operating frequency of the second piston is higher than the design frequency.
[0016] Among them, the correspondence between the figure marks and component names in Figure 1 is: 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.
[0017] Details
[0018] This application describes multiple embodiments, but this description is illustrative rather than restrictive. To make the objectives, technical solutions, and advantages of this disclosure more clearly understood, the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be noted that, unless there is a conflict, the embodiments and features of the embodiments in this application may be combined with each other in any manner.
[0019] The present application provides a free piston linear generator system, the tissue ventilation process of which can be adjusted to be more reasonable.
[0020] The present application also provides a control method for a free piston linear generator system.
[0021] The free piston linear generator system provided by the embodiment of the present disclosure, as shown in FIG1, comprises: a cylinder body 3, the cylinder body 3 having 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 being located between the first piston chamber and the second piston chamber, the air inlet 1 being located between the first piston chamber and the combustion chamber 7, and the exhaust port 2 being located between the second piston chamber and the combustion chamber 7; a piston group comprising a first piston 5 and a second piston 6, the first piston 5 being axially movable in the first piston chamber and being configured to open and close the air inlet 1, the second piston 6 being axially movable in the first piston chamber and being configured to open and close the air inlet 1, and the second piston 6 being axially movable in the second piston chamber and being configured to open and close the air inlet 1. The second piston chamber is configured to open and close the exhaust port 2. A first reset unit is provided between the first piston 5 and the end of the first piston chamber facing away from the combustion chamber 7. A second reset unit is provided between the second piston 6 and the end of the second piston chamber facing away from the combustion chamber 7. A functional mechanism is provided between the second piston 6 and the peripheral wall of the second piston chamber. The functional mechanism is configured to generate a driving force to accelerate and decelerate the second piston 6. The functional mechanism can also be configured to convert the mechanical energy of the second piston 6 into electrical energy for power generation. The combustion chamber 7 is provided with a spark plug 4, a fuel injector, and other structures. The axial direction is the axial direction of the cylinder body 3.
[0022] When the operating frequency of the second piston 6 is lower than the design frequency, the control function mechanism accelerates 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; when the operating frequency of the second piston 6 is higher than the design frequency, the control function mechanism decelerates 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.
[0023] Second piston 6 is at its right inner dead center (at the right end of the combustion chamber) and closes exhaust port 2. First piston 5 is at its left inner dead center (at the left end of the combustion chamber) and closes intake port 1. As shown by the solid line in Figure 2, ignition and combustion occur in combustion chamber 7 via spark plug 4. High-temperature, high-pressure gas pushes first piston 5 leftward, while second piston 6 expands rightward, producing work. Exhaust port 2 opens at time a, and intake port 1 opens at time b (b lags behind a). Both intake port 1 and exhaust port 2 remain open until first piston 5 moves leftward to its left outer dead center and second piston 6 moves rightward to its right outer dead center. During this process, the functional mechanism converts the mechanical energy of second piston 6 into electrical energy to generate electricity (backward motion). Then, the first piston 5 moves rightward toward the combustion chamber 7 under the action of the first reset unit, and the second piston 6 moves leftward 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. When the second piston 6 runs to time d, the second piston 6 closes the exhaust port 2 (d lags behind c). Finally, the first piston 5 moves to the inner dead center on the left side, and the second piston 6 moves to the inner dead center on the right side (opposite movement process).
[0024] 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 low emissions.
[0025] During actual use, when the operating frequency of the second piston 6 is lower than the design frequency, excessive mixture scavenging will occur during the process of the first piston 5 and the second piston moving toward each other to close the exhaust port 2. At this time, it is configured that the control function mechanism accelerates 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 (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), so that the second piston 6 closes the exhaust port 2 in advance (closed at time e in Figure 2, and the displacement time curve of the second piston 6 in this process changes to the dotted line in Figure 2), thereby shortening the exhaust process, reducing the escape of fresh air in the combustion chamber 7, and achieving precise control of the scavenging process.
[0026] During actual use, when the operating frequency of the second piston 6 is higher than the design frequency, the exhaust gas will be difficult to discharge when the first piston and the second piston move toward 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 away from 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 (closed at time f in Figure 3, and the displacement time curve of the second piston 6 in this process changes to the dotted line in Figure 3), thereby prolonging the exhaust process, facilitating the scavenging of exhaust gas, and achieving precise control of the scavenging process.
[0027] In some examples, as shown in FIG1 , 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, which increases the power generation efficiency.
[0028] In some examples, as shown in FIG. 1 , at least one of the functional mechanism and the energy conversion mechanism includes an electromagnet mechanism.
[0029] In some examples, as shown in FIG1 , the energy conversion mechanism includes: a first coil 11 disposed on the peripheral wall of the first piston cavity; and a first iron core 8 disposed within the first piston cavity and connected to the first piston 5. A first reset unit is located between the first iron core 8 and the end of the first piston cavity facing away from the combustion chamber 7. To ensure the service life of the functional mechanism, the first reset unit includes an air spring 12.
[0030] In some examples, as shown in FIG1 , the functional mechanism includes a second coil 10 disposed on the peripheral wall of the second piston cavity; a second iron core 9 disposed within the second piston cavity and connected to the second piston 6; and a second reset unit located between the second iron core 9 and the end of the second piston cavity facing away from the combustion chamber 7. To ensure the service life of the second reset unit, the second reset unit also includes an air spring 12.
[0031] In some examples, the axial distance between the 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 intake port 1 opens later than the exhaust port 2 during the backward movement, and the exhaust port 2 closes later than the intake port 1 during the forward movement.
[0032] Second piston 6 is at its right inner dead center, closing exhaust port 2. First piston 5 is at its left inner dead center, closing intake port 1. Spark plug 4 ignites combustion in combustion chamber 7. High-temperature, high-pressure gases push first piston 5 leftward, while second piston 6 expands rightward, producing work. Exhaust port 2 opens before intake port 1. Then, intake port 1 and exhaust port 2 remain open simultaneously until first piston 5 moves leftward to its left outer dead center and second piston 6 moves rightward to its right outer dead center. During this process, the functional mechanism and energy conversion mechanism convert mechanical energy into electrical energy, generating electricity (counter-movement process). Then, driven by the first reset unit, first piston 5 moves rightward toward combustion chamber 7, while second piston 6 moves leftward toward combustion chamber 7, driven by the second reset unit. Intake port 1 closes before exhaust port 2. Finally, first piston 5 reaches its left inner dead center and second piston 6 reaches its right inner dead center (counter-movement process).
[0033] The free piston linear generator system can use a conventional three-way catalytic converter to achieve stoichiometric combustion of exhaust gas.
[0034] The control method proposed in the embodiment of the present disclosure (not shown in the figure) includes: when the operating frequency of the second piston 6 is lower than the design frequency, during 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 accelerates the second piston 6, so that the second piston 6 closes the exhaust port 2 in advance, thereby shortening the exhaust process, reducing the escape of fresh air in the combustion chamber 7, and realizing precise control of the scavenging process.
[0035] In some examples, as shown in FIG2 , 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 , which can better achieve precise control of the scavenging process.
[0036] In some examples, as shown in FIG. 2 , during the back-to-back movement of the first piston 5 and the second piston 6 , the exhaust port 2 opens before the intake port 1 .
[0037] The control method proposed in the embodiment of the present disclosure (not shown in the figure) includes: when the operating frequency of the second piston 6 is higher than the design frequency, during 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 realizing precise control of the scavenging process.
[0038] In some examples, as shown in FIG3 , 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 , which can better achieve precise control of the scavenging process.
[0039] In some examples, as shown in FIG. 3 , during the back-to-back movement of the first piston 5 and the second piston 6 , the exhaust port 2 opens before the intake port 1 .
[0040] In summary, the technical solution provided by this application, the free-piston linear generator system, has a simple and compact structure. When the operating frequency of the second piston is lower than the design frequency, the process of the first and second pistons moving toward each other to close the exhaust port will cause excessive scavenging of the mixed gas. In this case, the control function mechanism is configured to accelerate the second piston, causing the second piston to close the exhaust port in advance, shortening the exhaust process and reducing the escape of fresh air in the combustion chamber. When the operating frequency of the second piston is higher than the design frequency, the process of the first and second pistons moving toward each other to close the exhaust port will cause poor exhaust gas discharge. In this case, the control function mechanism is configured to decelerate the second piston, causing the second piston to delay closing the exhaust port, prolonging the exhaust process and facilitating the scavenging of the exhaust gas.
[0041] In the description of the present disclosure, 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", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the structure referred to has a specific orientation, is constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present disclosure.
[0042] In the description of the embodiments of the present disclosure, unless otherwise expressly specified or limited, the terms "connection", "direct connection", "indirect connection", "fixed connection", "installation", and "assembly" should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integral connection. The terms "installation", "connection", and "fixed connection" can refer to direct connection, indirect connection through an intermediate medium, or internal communication between two components. For those skilled in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.
[0043] It should be noted that the above-described embodiments or implementations are merely illustrative and not restrictive. Therefore, the present disclosure is not limited to what is specifically shown and described herein. Various modifications, substitutions, or omissions may be made to the forms and details of the implementations without departing from the scope of the present disclosure.
Claims
1. A free piston linear generator system, comprising: 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 includes 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; 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.
2. The free piston linear generator system according to claim 1, wherein: When the operating frequency of the second piston is lower than the design frequency, the functional mechanism is controlled to increase the speed of the second piston during the process of the first piston and the second piston moving toward each other to close the exhaust port, so that the second piston closes the exhaust port in advance; When the operating frequency of the second piston is higher than the design frequency, the functional mechanism is controlled to decelerate the second piston during the process of the first piston and the second piston moving toward each other to close the exhaust port, so that the second piston delays closing the exhaust port.
3. The free piston linear generator system according to claim 2, wherein: 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.
4. The free piston linear generator system according to claim 3, wherein: The energy conversion mechanism includes an electromagnet mechanism.
5. The free piston linear generator system according to claim 1, wherein: The functional mechanism is also configured to convert mechanical energy into electrical energy.
6. The free piston linear generator system according to claim 5, wherein: The functional mechanism comprises an electromagnet mechanism.
7. The free piston linear generator system according to any one of claims 1 to 6, wherein: 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.
8. The free piston linear generator system according to any one of claims 1 to 6, wherein: At least one of the first reset unit and the second reset unit includes an air spring.
9. The free piston linear generator system according to any one of claims 1 to 6, wherein: 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.
10. A control method for a free piston linear generator system according to any one of claims 1 to 9, comprising: When the operating frequency of the second piston is lower than the design frequency, the functional mechanism is controlled to increase the speed of the second piston during the process of the first piston and the second piston moving toward each other to close the exhaust port, so that the second piston closes the exhaust port in advance.
11. The control method according to claim 10, wherein: 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.
12. A control method for a free piston linear generator system according to any one of claims 1 to 9, comprising: When the operating frequency of the second piston is higher than the design frequency, the functional mechanism is controlled to decelerate the second piston during the process of the first piston and the second piston moving toward each other to close the exhaust port, so that the second piston delays closing the exhaust port.
13. The control method according to claim 12, wherein: 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.