Dual piston linear engine with direct current scavenging and its working method

Abstract

The application discloses a double-piston direct-current scavenging type free-piston internal combustion linear generator, which comprises two combustion chambers arranged on the left and right sides of the linear generator, and piston mover assemblies reciprocating in the left and right combustion chambers; the top of the combustion chamber is provided with a controllable electromagnetic exhaust valve, an electronic spark igniter and an oil nozzle; the middle of the combustion chamber is attached with corresponding radiating fins; the bottom of the combustion chamber is connected with a corresponding scavenging chamber; the linear generator is provided with corresponding stator coil windings, linear Hall elements, piston assemblies and permanent magnets attached to the piston assemblies. The double-piston direct-current scavenging type free-piston internal combustion linear generator utilizes the direct-current scavenging technology, improves the scavenging quality of the existing free-piston internal combustion linear generator, changes the structure of the original piston assembly, and avoids the piston from impacting the combustion chamber cylinder cover or misfire caused by the change of external load when the system is running.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of range extenders of new energy hybrid electric vehicles, in particular to a double-piston direct-scavenging free-piston internal combustion linear generator and a working method thereof. BACKGROUND

[0002] With the increasing use of vehicles in daily life, great challenges have been brought to energy and environmental problems, and governments of various countries are seeking effective strategies for energy saving and emission reduction. For the automobile industry, on the one hand, it promotes the improvement of traditional internal combustion engines, and on the other hand, it promotes the vigorous development of new energy vehicles. In the current development process, new energy vehicles are mainly divided into three forms: pure electric vehicles, fuel cell vehicles and hybrid electric vehicles. However, pure electric vehicles are limited by battery technology and the number of ground charging piles, and have a short range. Fuel cell vehicles are limited by the development of electrochemical fuel technology and cannot be widely used. Hybrid electric vehicles can alleviate these situations to a certain extent. Under this background, since the free-piston internal combustion linear generator has the advantages of compact structure, high power density, strong fuel adaptability and high energy utilization rate, using the free-piston internal combustion linear generator as a range extender of a hybrid electric vehicle has a great application prospect. At the same time, after the free-piston internal combustion linear generator is multi-cylindered and modularized, it can also be applied to the power source of deep-sea exploration devices and the process of aerospace research. In addition, after being miniaturized and portable, it can be used as a power source for some portable military or civilian equipment.

[0003] At present, the research on the free-piston internal combustion linear generator mainly focuses on the double-piston structure. Since the free-piston internal combustion linear generator cancels the restriction of the crank connecting rod mechanism of the traditional internal combustion engine, the movement of the piston assembly is mainly controlled by the combustion chambers on the left and right sides. At the same time, the double-piston structure uses a two-stroke cycle mode, and there is no separate intake and exhaust process in the four-stroke cycle mode. The cross-flow scavenging mode is mostly used for scavenging. In this mode, the closing of the intake port and the exhaust port is determined by the piston. In the scavenging process, the intake port closes earlier than the exhaust port, which not only causes the after-exhaust phenomenon, but also forms a scavenging dead zone at the top of the cylinder, causing waste gas residue phenomenon, and the scavenging quality is poor. In addition, during the stable operation of the free-piston internal combustion linear generator system, due to the change of external load or the change of top dead center position, the piston assembly may hit the cylinder head or cause misfire. SUMMARY

[0004] The purpose of the present application is to provide a double-piston direct-scavenging free-piston internal combustion linear generator and a working method thereof. The direct-scavenging technology is combined to improve the scavenging performance of the system. The present application provides a new piston assembly style, which avoids the occurrence of piston hitting the combustion chamber cylinder head or misfire due to the change of external load.

[0005] The technical scheme adopted by the present application is:

[0006] A double-piston direct-current scavenging type free-piston internal combustion linear generator, comprising a left combustion chamber, a right combustion chamber and a mover piston assembly, the mover piston assembly being located between the left combustion chamber and the right combustion chamber,

[0007] The left combustion chamber cylinder head is provided with a left controllable electromagnetic exhaust valve, a left electronic spark igniter and a left fuel nozzle, the right combustion chamber cylinder head is provided with a right controllable electromagnetic exhaust valve, a right electronic spark igniter and a right fuel nozzle, the outer sides of the left combustion chamber and the right combustion chamber are respectively provided with scavenging chambers, a coil winding and a linear Hall element are arranged between the two scavenging chambers, the outer side of the mover piston assembly comprises a permanent magnet arranged opposite to the coil winding, the scavenging chamber comprises an air inlet and a scavenging port, and the mover piston assembly can open and close the scavenging port during movement between the left combustion chamber and the right combustion chamber.

[0008] Further, during movement of the mover piston assembly from one combustion chamber to the other combustion chamber, the controllable electromagnetic exhaust valve of the one combustion chamber is opened earlier than the scavenging port of the one combustion chamber, and the controllable electromagnetic exhaust valve of the other combustion chamber is closed earlier than the scavenging port of the other combustion chamber.

[0009] Further, the left combustion chamber and the right combustion chamber are both externally provided with cooling fins.

[0010] Further, the scavenging chamber is symmetrically provided with six scavenging ports.

[0011] Further, the coil winding is arranged in a plurality of stator teeth.

[0012] Further, the linear Hall element comprises two, both of which are mounted on the stator teeth.

[0013] Further, the distance between the two linear Hall elements is half of the pole pitch.

[0014] Further, the mover piston assembly comprises a mover piston assembly body and a permanent magnet support located in the middle of the mover piston assembly body, the permanent magnet support and the mover piston assembly body are connected through a connecting piece, the connecting piece is located in the middle between the mover piston assembly body and the permanent magnet support, the permanent magnet support is located between the left side part of the connecting piece and the mover piston assembly body to form a left side space, and the left combustion chamber cylinder head extends into the left side space, the permanent magnet support is located between the right side part of the connecting piece and the mover piston assembly body to form a right side space, and the right combustion chamber cylinder head extends into the right side space.

[0015] According to the working method of the double-piston straight-flow scavenging type free-piston internal combustion linear generator,

[0016] The working processes of the left combustion chamber and the right combustion chamber respectively include two strokes, a first stroke from a top dead center to a bottom dead center, and a second stroke from the bottom dead center to the top dead center, the working strokes of the left combustion chamber and the right combustion chamber are opposite, and the specific process is as follows:

[0017] The combustible mixture in the left combustion chamber which has been compressed is ignited by the left electronic spark igniter, the combustible mixture in the left combustion chamber is ignited, high temperature and high pressure act on the surface of the mover piston assembly, the mover piston assembly is driven to move from the top dead center to the bottom dead center, and enters a power stroke, when the position information of the mover piston assembly detected and fed back by the linear Hall element reaches a preset opening position of the left controllable electromagnetic exhaust valve, the left controllable electromagnetic exhaust valve is opened, a part of the exhaust gas in the left combustion chamber is preferentially discharged under the action of the internal and external pressure difference, meanwhile, the mover piston assembly continues to move to the bottom dead center, and gradually opens the scavenging port on the cylinder wall of the left combustion chamber, enters a straight-flow scavenging process, and the airflow spirally rises after entering the left combustion chamber, and accelerates to push out the exhaust gas,

[0018] When the mover piston assembly reaches the bottom dead center of the left combustion chamber, the left combustion chamber completes the first stroke, the right combustion chamber performs the second stroke in the process that the left combustion chamber completes the first stroke, after the left combustion chamber completes the first stroke, the right combustion chamber enters the first stroke, and the left combustion chamber enters the second stroke, the right combustion chamber drives the mover piston assembly to move to the top dead center of the left combustion chamber, when the position information of the mover piston assembly detected and fed back by the linear Hall element reaches a preset closing position of the left controllable electromagnetic exhaust valve, the left controllable electromagnetic exhaust valve is closed, but at this time, the scavenging port is not completely closed, meanwhile, the mover piston assembly continues to move to the top dead center, the scavenging port is gradually closed under the action of the mover piston assembly, when the position information of the mover piston assembly detected and fed back by the linear Hall element reaches a preset left fuel nozzle position, the left fuel nozzle performs in-cylinder direct injection into the left combustion chamber, so that the fuel is mixed with the incoming fresh air to form the combustible mixture, the mover piston assembly continues to move to the top dead center of the left combustion chamber, and the left combustion chamber enters a compression stroke, when the position information of the mover piston assembly detected and fed back by the linear Hall element reaches a preset ignition position of the left electronic spark igniter, the left combustion chamber is ignited, and the ignition position is set before the top dead center.

[0019] The double-piston straight-flow scavenging type free-piston internal combustion linear generator device has the following beneficial effects:

[0020] (1) The double-piston straight-flow scavenging type free-piston internal combustion linear generator device has the function of power generation, and can meet the requirements of the range extending technology of the hybrid electric vehicle;

[0021] (2) On the basis of the original double-piston free-piston internal combustion linear generator, direct current scavenging is improved to improve the scavenging effect and promote the overall power generation efficiency;

[0022] (3) On the basis of the original piston assembly, a new piston assembly style is designed. The original piston assembly is a polished rod type piston. A permanent magnet support part bearing permanent magnets is installed on the original piston assembly. At the same time, this part is rigidly connected with the piston assembly body through a connecting piece with a cross section. The cross section functions to stop the movement of the piston assembly when it hits the cylinder designed for the linear generator part, which can effectively avoid the occurrence of piston impact on the combustion chamber cylinder cover or misfire due to changes in external load.

[0023] In addition to the purposes, features and advantages described above, the present application has other purposes, features and advantages. The present application will be further described in detail below with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a structural schematic diagram of the double-piston direct-current scavenging type free-piston internal combustion linear generator device of the present application.

[0025] Figure 2 is a structural schematic diagram of the piston assembly in the double-piston direct-current scavenging type free-piston internal combustion linear generator device of the present application.

[0026] Figure 3 is a connection schematic diagram of the combustion chamber and the scavenging chamber in the double-piston direct-current scavenging type free-piston internal combustion linear generator device of the present application.

[0027] Figure 4 is a schematic diagram of the corresponding positions of each component when the one-side combustion chamber is running.

[0028] Figure 5 is a direct-current scavenging schematic diagram in the double-piston direct-current scavenging type free-piston internal combustion linear generator device of the present application.

[0029] In the figure, 1, 14. Controllable electromagnetic exhaust valve, 2, 15. Electronic spark igniter, 3, 16. Fuel injector, 4. Radiator fin, 5. Scavenging chamber, 6. Scavenging port, 7. Intake port, 8. Coil winding, 9. Permanent magnet, 10. Linear Hall element, 11. Stator tooth, 12. Left combustion chamber, 13. Right combustion chamber, 17. Mover piston assembly, 17-1. Mover piston assembly body, 17-2. Permanent magnet support part, 17-3. Connecting piece. DETAILED DESCRIPTION

[0030] The present application will be described in detail below in combination with the drawings and specific embodiments.

[0031] The present invention discloses the structure of a dual-piston DC scavenging free piston internal combustion linear generator device, as follows: Figure 1 As shown, the system includes a controllable electromagnetic exhaust valve 1, an electronic spark igniter 2, and a fuel injector 3 located on the cylinder head of the left combustion chamber 12; a controllable electromagnetic exhaust valve 14, an electronic spark igniter 15, and a fuel injector 16 located on the cylinder head of the right combustion chamber 13; corresponding heat sinks 4 are provided in the middle of the housings of the left combustion chamber 12 and the right combustion chamber 13; corresponding scavenging chambers 5 are connected to the lower part; a coil winding 8, a permanent magnet 9 attached to the moving piston assembly 17, and a linear Hall element 10 mounted on the stator teeth 11 are arranged between them; the moving piston assembly 17 reciprocates between the left combustion chamber 12 and the right combustion chamber 13. Figure 2 The diagram shown is a structural schematic of the designed moving piston assembly 17; as shown... Figure 3 The diagram shows the connection between the left combustion chamber 12 and the scavenging chamber 5. They are connected by six symmetrical scavenging ports 6, each with a certain angle of inclination. An air inlet 7 is located on the line of symmetry between the scavenging chamber 5 and the scavenging ports 6. Figure 4 As shown, the preset positions of each component in the combustion chamber on one side during operation are as follows. Taking the left combustion chamber 12 as an example, TDC is the top dead center of the combustion chamber on this side, BDC is the bottom dead center of the combustion chamber on this side, X1 is the preset open position of the controllable electromagnetic exhaust valve 1, X2 is the preset open position of the scavenging port 6, X3 is the preset closed position of the controllable electromagnetic exhaust valve 1, X4 is the preset closed position of the scavenging port 6 and the preset open position of the fuel injector 3, X5 is the preset closed position of the fuel injector 3, and X6 is the preset ignition position of the electronic spark igniter 2.

[0032] Combination Figure 2 The moving piston assembly 17 includes a moving piston assembly body 17-1 and a permanent magnet support 17-2 located in the middle of the moving piston assembly body 17-1. The permanent magnet support 17-2 is connected to the moving piston assembly body 17-2 via a connector 17-3. The connector 17-3 is located in the middle between the moving piston assembly body 17-1 and the permanent magnet support 17-2. The permanent magnet support 17-2 is located between the left side of the connector 17-3 and the moving piston assembly body 17-1. A left-side space is formed, with the cylinder head of the left combustion chamber 12 extending into it. The permanent magnet support 17-2, located on the right side of the connector 17-3, forms a right-side space with the mover piston assembly body 17-1. The cylinder head of the right combustion chamber 13 extends into this right-side space. Under the limitation of the connector 17-3, the movement of the mover piston assembly 17 between the left combustion chamber 12 and the right combustion chamber 13 is limited, effectively preventing the piston assembly from impacting the combustion chamber cylinder head or causing misfire due to changes in external load.

[0033] The working principle of the present application is that when the device is in stable operation, the mover piston assembly 17 reciprocates under the action of the left combustion chamber 12 and the right combustion chamber 13, and the permanent magnet 9 attached to the mover piston assembly 17 also reciprocates, and the coil winding 8 continuously cuts the magnetic lines to generate induced electromotive force. In the operation process, the real-time displacement of the mover piston assembly 17 is needed as a feedback variable to control the opening and closing of the controllable electromagnetic exhaust valve 1, 14, the electronic spark igniter 2, 15, and the fuel nozzle 3, 16, so two linear Hall elements 10 are installed on the stator teeth 11 of the linear generator part to detect, and the distance between the two linear Hall elements 10 is half of the pole pitch. When the mover piston assembly 17 moves, the output voltage of the linear Hall element 10 should be a displacement-varying cosine signal, and the two signals are analog processed to obtain the real-time displacement of the mover piston assembly 17. By comparing the detected real-time displacement of the mover piston assembly 17 with the preset controllable electromagnetic exhaust valve 1, 14 opening / closing position, fuel nozzle 3, 16 injection position, and electronic spark igniter 2, 15 ignition position, the corresponding working signal is given.

[0034] In steady-state operation, it can be divided into two strokes, the first stroke: top dead center→bottom dead center, and the second stroke: bottom dead center→top dead center. Taking the left combustion chamber 12 as an example, the working process is described as follows:

[0035] First stroke: top dead center→bottom dead center, assuming that the left combustion chamber 12 is filled with compressed combustible mixture, and the electronic spark igniter 2 ignites the combustible mixture in the left combustion chamber 12, the high temperature and high pressure act on the surface of the mover piston assembly 17, pushing the mover piston assembly 17 to move from the top dead center to the bottom dead center, entering the power stroke. When the linear Hall element 10 detects the position information of the mover piston assembly 17 reaches the preset opening position X1 of the controllable electromagnetic exhaust valve 1, the controllable electromagnetic exhaust valve 1 opens, and a part of the exhaust gas in the left combustion chamber 12 is preferentially discharged under the action of the internal and external pressure difference, while the mover piston assembly 17 continues to move to the bottom dead center, and gradually reaches the preset opening position X2 of the left combustion chamber 12 cylinder wall scavenging port 6, entering the direct scavenging process, as shown in Figure 5 , which is a schematic diagram of direct scavenging. The gas flow spirally rises after entering the combustion chamber, accelerating the exhaust gas.

[0036] The second stroke: bottom dead center→top dead center, when the mover piston assembly 17 reaches the bottom dead center of the left combustion chamber 12, the first stroke is entered by the right combustion chamber 13, and the mover piston assembly 17 is pushed to move to the top dead center of the left combustion chamber 12, when the linear Hall element 10 detects the feedback position information of the mover piston assembly 17 reaches the preset closing position X3 of the controllable electromagnetic exhaust valve 1, the controllable electromagnetic exhaust valve 1 is closed, but at this time the scavenging port 6 is not completely closed, and the controllable electromagnetic exhaust valve 1 is closed earlier than the scavenging port 6, which can obtain the effect of supplementing intake air. At the same time, the mover piston assembly 17 continues to move to the top dead center, when the linear Hall element 10 detects the feedback position information of the mover piston assembly 17 reaches the preset closing position of the scavenging port 6 and the preset opening position X4 of the oil nozzle 3, the scavenging port 6 is completely closed under the action of the mover piston assembly 17, and the oil nozzle 3 sprays into the left combustion chamber 12 to form a combustible mixture with the entering fresh air, when reaching the preset closing position X5 of the oil nozzle 3, the oil nozzle 3 is closed. The mover piston assembly 17 continues to move to the top dead center of the left combustion chamber 12, and the left combustion chamber 12 enters the corresponding compression stroke, when the linear Hall element 10 detects the feedback position information of the mover piston assembly 17 reaches the preset ignition position X6 of the electronic spark igniter 2, the left combustion chamber 12 is ignited, and the ignition position is set before the top dead center.

[0037] The mover piston assembly 17 reciprocates linearly between the first stroke and the second stroke, driving the permanent magnet 9 on the mover piston assembly 17, and the coil winding 8 continuously cuts the magnetic lines, thereby generating an induced electromotive force.

[0038] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for operating a double-piston linear engine with uniflow scavenging, the engine comprising a left combustion chamber (12), a right combustion chamber (13), and a mover piston assembly (17) located between the left combustion chamber (12) and the right combustion chamber (13), the left combustion chamber (12) being provided with a left controllable electromagnetic exhaust valve (1), a left electronic spark igniter (2), and a left fuel injector (3) on a cylinder head thereof, the right combustion chamber (13) being provided with a right controllable electromagnetic exhaust valve (1), a right electronic spark igniter (2), and a right fuel injector (3) on a cylinder head thereof, the left combustion chamber (12) and the right combustion chamber (13) being respectively provided with a scavenging chamber (5) on an outer side thereof, the two scavenging chambers (5) being provided with a coil winding (8) and a linear Hall element (10) therebetween, the mover piston assembly (17) comprising a permanent magnet (9) located opposite to the coil winding (8) on an outer side thereof, the scavenging chamber (5) comprising an intake port (7) and a scavenging port (6), the mover piston assembly (17) being capable of opening and closing the scavenging port (6) during movement between the left combustion chamber (12) and the right combustion chamber (13), during movement of the mover piston assembly (17) from one combustion chamber to the other combustion chamber, the controllable electromagnetic exhaust valve of the one combustion chamber is opened earlier than the scavenging port of the one combustion chamber, and the controllable electromagnetic exhaust valve of the other combustion chamber is closed later than the scavenging port of the other combustion chamber, the method comprising the following steps: characterized in that the working process of the left combustion chamber (12) and the right combustion chamber (13) respectively comprises two strokes, a first stroke from a top dead center to a bottom dead center, and a second stroke from the bottom dead center to the top dead center, the working strokes of the left combustion chamber (12) and the right combustion chamber (13) being opposite to each other, and the specific process being as follows: combustible mixture in the left combustion chamber (12) is ignited by the left electronic spark igniter (2), the combustible mixture in the left combustion chamber (12) is ignited, high temperature and high pressure act on a surface of the mover piston assembly (17), the mover piston assembly (17) is driven to move from the top dead center to the bottom dead center, and enters a power stroke, when position information of the mover piston assembly (17) detected by the linear Hall element (10) reaches a preset opening position of the left controllable electromagnetic exhaust valve (1), the left controllable electromagnetic exhaust valve (1) is opened, a part of exhaust gas in the left combustion chamber (12) is preferentially discharged under the action of an internal and external pressure difference, the mover piston assembly (17) continues to move to the bottom dead center, and the scavenging port (6) on the cylinder wall of the left combustion chamber (12) is gradually opened, a direct current scavenging process is entered, and air flow spirally rises after entering the left combustion chamber (12) to accelerate the exhaust gas, ​ When the mover piston assembly (17) reaches the bottom dead center of the left combustion chamber (12), the left combustion chamber (12) completes the first stroke, and the right combustion chamber (13) performs the second stroke during the completion of the first stroke of the left combustion chamber (12). After the left combustion chamber (12) completes the first stroke, the right combustion chamber (13) enters the first stroke, and the left combustion chamber (12) enters the second stroke at the same time. The right combustion chamber (13) pushes the mover piston assembly (17) to move to the top dead center of the left combustion chamber (12). When the linear Hall element (10) detects the feedback position information of the mover piston assembly (17) reaches the preset left controllable electromagnetic exhaust valve (1) closing position, the left controllable electromagnetic exhaust valve (1) is closed, but the scavenging port (6) is not completely closed at this time, and the mover piston assembly (17) continues to move to the top dead center. The scavenging port (6) is gradually closed under the action of the mover piston assembly (17). When the linear Hall element (10) detects the feedback position information of the mover piston assembly (17) reaches the preset left fuel nozzle (3) position, the left fuel nozzle (3) performs in-cylinder direct injection into the left combustion chamber (12), mixes the fuel with the incoming fresh air to form a combustible mixture, and the mover piston assembly (17) continues to move to the top dead center of the left combustion chamber (12). The left combustion chamber (12) enters the compression stroke. When the linear Hall element (10) detects the feedback position information of the mover piston assembly (17) reaches the preset left electronic spark igniter (2) ignition position, the left combustion chamber (12) is ignited. The ignition position is set before the top dead center.

2. The method of working according to claim 1, characterized in that, The left combustion chamber (12) and the right combustion chamber (13) are both provided with cooling fins (4) outside.

3. The method of claim 1, wherein, The scavenging chamber (5) is provided with six scavenging ports (6) symmetrically on the left and right.

4. The method of claim 1, wherein, The coil winding (8) is wound in the plurality of stator teeth (11).

5. The method of working according to claim 4, characterized in that, The linear Hall element (10) includes two, which are installed on the stator teeth (11).

6. The method of working according to claim 5, characterized in that, The distance between the two linear Hall elements (10) is half of the pole pitch.

7. The method of working according to any one of claims 1-6, characterized in that, The mover piston assembly (17) includes a mover piston assembly body (17-1) and a permanent magnet support (17-2) located in the middle of the mover piston assembly body (17-1). The permanent magnet support (17-2) and the mover piston assembly body (17-1) are connected by a connecting piece (17-3) located in the middle between the mover piston assembly body (17-1) and the permanent magnet support (17-2). The permanent magnet support (17-2) is located between the left part of the connecting piece (17-3) and the mover piston assembly body (17-1) to form a left space, and the left combustion chamber (12) cover extends into the left space. The permanent magnet support (17-2) is located between the right part of the connecting piece (17-3) and the mover piston assembly body (17-1) to form a right space, and the right combustion chamber (13) cover extends into the right space.

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