CN104929765B - Stepless speed regulating single-piston type hydraulic free piston engine - Google Patents

Abstract

The invention discloses a single-piston hydraulic free-piston engine with stepless speed regulation, which belongs to the technical field of hybrid power. The hydraulic free piston engine includes a high pressure accumulator, a low pressure accumulator, a constant power transformer, a control valve, a cylinder block, a fuel injector and a piston assembly. The cylinder block provides the installation chamber for the piston assembly, and thus forms the piston oil chamber, the starting oil chamber and the scavenging chamber. Port A of the constant power transformer is connected to the high-voltage accumulator, port C is connected to the low-voltage accumulator, and port B is connected to the piston oil chamber. A control valve is set so that the high-pressure accumulator communicates with the starting oil chamber when the hydraulic free-piston engine is in the starting condition; and the low-pressure accumulator communicates with the starting oil chamber during the first stroke and the second stroke. The pressure change of the engine through the constant power transformer can directly transform the hydraulic energy and fuel combustion heat energy, and at the same time, the stepless speed regulation of the free piston engine can be realized by changing the port pressure of the constant power transformer.

Description

A single-piston hydraulic free-piston engine with stepless speed regulation

technical field

The invention relates to a free-piston engine, in particular to a single-piston hydraulic free-piston engine with stepless speed regulation, and belongs to the technical field of hybrid power.

technical background

As the global energy crisis and environmental degradation become increasingly apparent, the requirements for energy-saving and environmental protection performance of engines are also increasing. At the same time, with the rapid development and application of the internal combustion engine industry, people have higher and higher requirements for the structure, efficiency, power density and pollution emission of the power plant. On the one hand, people are committed to the improvement and perfection of traditional engines, and on the other hand, they are diligently seeking new power devices. The hydraulic free piston engine is a new type of special internal combustion engine developed under this background. The hydraulic free piston engine is a synthesis of modern hydraulic technology, microelectronics technology, control technology and internal combustion engine technology. The hydraulic free-piston linear engine realizes the reciprocating motion of the piston through the oil supply of the accumulator and the combustion of the fuel. The compression ratio can be flexibly adjusted during the working process. It has potential advantages such as high power density, wide range of fuel types, and light emission pollution. Therefore, the hydraulic free piston engine has high practical value and good development prospects.

In today's research work on hydraulic free piston engines, the rational design and optimization of its structure is also an important direction of its development. The existing hydraulic free-piston linear motors have disadvantages such as uncompact structure, poor processing technology, complicated control and the like. In the existing opposed-piston and double-piston free-piston engines, the arrangement of the pistons in these two arrangements will cause the axial size of the piston assembly to be too large, making the structure of the hydraulic free-piston engine not compact, and the piston assembly The disadvantages such as poor processing technology.

At the same time, in the development of hydraulic free piston engines, improving efficiency has always been the goal pursued by everyone. The hydraulic free piston engine is a device that organically integrates a fuel combustion device and a hydraulic device to convert the chemical energy of the fuel into hydraulic energy. Among the many inventions about the hydraulic free-piston engine nowadays, in the process of energy conversion, the mechanism is complex, the conversion is cumbersome, and there are many losses, which seriously reduce the efficiency of the hydraulic free-piston engine.

Contents of the invention

In view of this, the present invention proposes a single-piston hydraulic free-piston engine with stepless speed regulation, which uses a constant power transformer to shorten the energy transmission chain, simplify the structure, and adopt a single-piston structure to make the engine compact. At the same time, the function of stepless speed regulation of the engine can be realized by changing the pressure at the port of the constant power transformer.

The single-piston hydraulic free-piston engine with stepless speed regulation includes: a high-pressure accumulator, a low-voltage accumulator, a constant power transformer, a cylinder block, a fuel injector and a piston assembly; the piston assembly includes a cylinder piston, a piston A connecting rod and a pump piston; the constant power transformer has three ports, namely port A, port B and port C.

The connection relationship is as follows: the piston assembly is located in the cavity of the cylinder body; the cylinder body is divided into three sections along the axial direction according to the different diameters of the inner cavity, respectively cylindrical section A, cylindrical section B and cylindrical section C; The diameter of the cylindrical section B is greater than the diameter of the cylindrical section A; the pump piston is a disc-shaped structure matching the inner diameter of the cylindrical section; the cylinder piston is matched with the inner diameter of the cylindrical section A Disc-shaped structure; the inner cavity of the cylindrical section C is divided into chamber A and chamber B through a partition that only passes through the piston connecting rod, and the pump piston is located in chamber B to separate chamber B It is the piston oil chamber and the starting oil chamber, wherein the starting oil chamber is the chamber between the partition plate and the pump piston; the inner cavity of the cylindrical section A is the scavenging chamber, and the corresponding A fuel injector and an air valve are arranged on the inner bottom surface; an intake check valve is arranged on the peripheral surface of the chamber A.

Port A of the constant power transformer is connected to the high-voltage accumulator through an oil circuit, port C is connected to the low-pressure accumulator through an oil circuit, and port B is connected to the piston oil chamber through an oil circuit;

In addition, by setting the control valve so that the hydraulic free piston engine is in the starting condition, the high-pressure accumulator communicates with the starting oil chamber; during the first stroke and the second stroke, the low-pressure accumulator communicates with the starting oil chamber connected.

A guide wall for guiding the movement of the cylinder piston is arranged in the cylindrical section B along its axial direction; more than two ventilation holes are arranged on the circumferential surface of the guide wall.

Beneficial effect:

(1) The constant power transformer is used in the hydraulic free piston engine, which can shorten the energy transmission chain, simplify the structure of the engine, and improve the efficiency and reliability of the engine.

(2) The movement law of the piston assembly can be changed by adjusting the port pressure of the constant power transformer, the continuous line stepless speed regulation, and the compression ratio of the engine can be flexibly changed at the same time.

(3) The single-piston structure is adopted, so that the overall structure of the engine is compact, and it can be made into a micro-engine, which can be widely used in fields such as micro-robots and vehicles.

Description of drawings

Fig. 1 is the structural representation of the first kind of embodiment of this free piston engine;

Fig. 2 is the schematic diagram of the starting working condition of this free piston engine;

Fig. 3 is a position diagram of each element in the cylinder body of the first stroke;

Fig. 4 is the location diagram of each element in the cylinder body of the second stroke;

Fig. 5 is a structural schematic diagram of a hollow guide wall;

Fig. 6 is a structural schematic diagram of the second embodiment of the free piston engine.

Among them: 1-high pressure accumulator, 2-constant power transformer, 3-control valve A, 4-starting oil chamber, 5-intake check valve, 6-cylinder block, 7-scavenging chamber, 8-valve, 9-Injector, 10-Cylinder piston, 11-Guide wall, 12-Piston connecting rod, 13-Control valve B, 14-Pump piston, 15-Piston oil chamber, 16-Low pressure accumulator, 17-Control valve C

detailed description

The present invention will be described in detail below with reference to the accompanying drawings and examples.

This embodiment provides a single-piston hydraulic free-piston engine with stepless speed regulation. The pressure change generated by the constant power transformation device makes the hydraulic energy and the fuel combustion heat energy directly converted, which can solve the problem that the existing linear engine is not compact in structure and complex in control. , complex energy conversion mechanism, low thermal efficiency and other issues. The stepless speed regulation function of the piston is realized by changing the pressure at both ends of the constant power transformer.

Example 1:

The hydraulic free piston engine includes: a high pressure accumulator 1, a low pressure accumulator 16, a constant power transformer 2, a control valve A3, a control valve B13, a cylinder block 6, a fuel injector 9 and a piston assembly. Wherein the cylinder block 6 is the body, the high-pressure accumulator 1 and the low-pressure accumulator 16 are energy storage devices, and the piston assembly includes a cylinder piston 10, a piston connecting rod 12 and a pump piston 14 connected in sequence. The constant power transformer 2 has three ports, namely port A, port B and port C.

The overall connection relationship is shown in FIG. 1 , the cylinder block 6 is a hollow cylindrical structure, providing a mounting cavity for the piston assembly. The cylinder block 6 can be divided into three sections in the axial direction according to different diameters. From left to right, there are cylindrical section A, cylindrical section B and cylindrical section C, wherein the diameter of cylindrical section B is larger than that of cylindrical section B. Diameters of segment C and cylindrical segment A. The pump piston 14 is a disc-shaped structure matching the inner diameter of the cylindrical section C, and the cylinder piston 10 is a disc-shaped structure matching the inner diameter of the cylindrical section A. The inner cavity of the cylindrical section C is divided into a chamber A and a chamber B by a partition plate through which only the piston connecting rod 12 passes, and the pump piston 14 is located in the chamber B, and the chamber B is divided into piston oil The chamber 15 and the starting oil chamber 4, wherein the starting oil chamber 4 is the chamber between the partition plate and the pump piston 14. The inner cavity of the cylindrical section A is a scavenging chamber 7 , and a fuel injector 9 and an air valve 8 are arranged on the inner bottom surface corresponding to the scavenging chamber 7 . A hole is opened on the circumferential surface of the chamber A, and an intake check valve 5 is arranged at the opening. The function of the intake check valve 5 is to charge fresh gas into the scavenging chamber 7 . A guide wall 11 for guiding the movement of the cylinder piston 10 is arranged in the cylindrical section B along its axial direction, and a plurality of air holes are processed on the guide wall 11, so as to ensure the air flow from the intake check valve. 5. The incoming fresh gas can enter the scavenging chamber 7 (the flow route of the gas is: intake check valve 5-ventilation hole-annular cavity between the guide wall 11 and the cylindrical section B-ventilation hole-scavenging chamber) .

The high-voltage accumulator 1 is connected to the port A of the constant power transformer 2 and the starting oil chamber 4 through two oil circuits; a control valve A is set on the oil circuit connected to the starting oil chamber 4 . The control valve A is a two-position one-way solenoid valve. When it is in the left position, the high-pressure accumulator 1 communicates with the starting oil chamber 4. When it is in the right position, the oil circuit is cut off at the control valve A. The low-pressure accumulator 16 is connected to the port C of the constant power transformer 2 and the piston oil chamber 15 (or the starting oil chamber 4) respectively through two oil passages; a control valve B is set on the oil passage connected to the piston oil chamber 15 . The control valve B is a two-position two-way solenoid valve. When it is in the upper position, the low-pressure accumulator 16 communicates with the starting oil chamber 4; when it is in the lower position, the low-pressure accumulator 16 communicates with the piston oil chamber. 15 connected. The port B of the constant power transformer 2 communicates directly with the piston oil cavity 15 .

The function of the constant power transformer 2 is to generate different pressures at its ports A and B, so that the oil flows from the port C into the low-pressure accumulator 16 or supplies the oil in the low-pressure accumulator 16 to the high-pressure accumulator 1 , to reduce the energy transfer chain, optimize the structure, and improve the thermal efficiency. At the same time, changing the port pressure of the constant power transformer can realize the stepless speed regulation function of the engine.

Below in conjunction with Fig. 2 to Fig. 5, the working principle of this free-piston engine is specifically described:

The free-piston engine includes an internal combustion engine part and a hydraulic part, wherein the internal combustion engine part adopts the working principle of a two-stroke diesel engine and a direct current scavenging method; the hydraulic part provides energy for the compression stroke and stores the energy generated by the power stroke in the accumulator. During the working process, the piston assembly formed by the cylinder piston 11, the pump piston 14 and the piston connecting rod 12 performs circular reciprocating linear motion. During the compression stroke, the oil flowing out from the high-voltage accumulator 1 flows into the constant power transformer 2 through the port A of the constant power transformer 2, and the pressure at the port B of the constant power transformer 2 is higher than that of the port A. Its port B flows into the pump piston oil chamber 15 to provide energy for the compression stroke of the internal combustion engine, and the other way flows into the low-pressure accumulator 16 from its port C. During the power stroke, the pressure at the port A of the constant power transformer 2 decreases, and the oil in the pump piston oil chamber 15 and the oil in the low pressure accumulator 16 converge at the port A of the constant power transformer 2 to complete the power output. During the movement of the piston assembly, when it is moved to the right to its maximum stroke, the position of the cylinder piston 10 is its bottom dead center position, as shown in Figure 3; when it is moved to the left to its maximum stroke, the cylinder piston The position of 10 is its top dead center position, as shown in Figure 4.

Before starting, since the cylinder piston 11 can be located at any position in the scavenging chamber 7, the cylinder piston 10 needs to be moved to a specific position through the starting condition. The position of the piston assembly is shown in Figure 2 before starting the working condition. First move the control valve A3 to the left position, the control valve B13 to the lower position, and at the same time close the constant power transformer 2. At this time, the high-voltage accumulator 1 communicates with the starting oil chamber 4 through the oil circuit, and the pump piston oil chamber 15 passes through the oil circuit. It communicates with the low-pressure accumulator 16 . The high-pressure accumulator 1 injects high-pressure oil into the starting oil chamber 4, and the high-pressure oil in the starting oil chamber 4 pushes the pump piston 14 to move to the right, that is, the piston assembly moves to the right. During the rightward movement of the piston assembly, the pump piston 14 hydraulically injects the oil in the pump piston oil chamber 15 into the low-pressure accumulator 16 . When the cylinder piston 10 moves rightward to its bottom dead center position, the start-up condition ends. At this time, the position of the piston assembly in the cylinder block 6 is shown in FIG. 3 .

After the start-up condition is over, adjust the control valve A3 to the right position, control valve B13 to the upper position, and open the valve 8, as shown in Figure 3; the engine enters the first stroke, and the low-pressure accumulator 16 communicates with the start oil chamber 4 at this time . The high-voltage accumulator 1 injects high-pressure hydraulic oil into port A of the constant power transformer 2, and the pressure at port A is lower than that at port B, and because the power of the constant power transformer 2 is constant, the high-pressure hydraulic oil is shunted in the constant power transformer 2, all the way It flows into the low-pressure accumulator 16 through port C, and flows into the pump piston cavity 15 through port B all the way, thereby pushing the pump piston 14 to move to the left, that is, the piston assembly moves to the left, so that the cylinder piston 10 moves from the bottom dead center position to the top dead center position . During this process, the air in the scavenging chamber 7 is discharged outside through the air valve 8, and the fresh air from the outside enters the scavenging chamber 7 through the intake check valve 5, thereby realizing ventilation. During the leftward movement of the pump piston 14 , the starting oil fluid in the starting oil chamber 4 flows into the low-pressure accumulator 16 through the control valve 14 . The flow path of the oil in the first stroke is shown by the arrows in Figure 3. When the cylinder piston 10 moves to the left to the set position (in this example, when the cylinder piston 10 moves to the transition of the cylindrical section A and the cylindrical section B), the valve 8 and the intake check valve 5 are closed, and the sweep The air chamber 7 becomes a closed cavity and enters the compression stroke. During the compression stroke, the air in the scavenging chamber 7 is compressed because the cylinder piston 10 continues to move to the left. When the cylinder piston 10 approaches its top dead center position, the fuel injector 9 is activated to inject fuel into the gas cavity and ignites by itself. Combustion, the pressure and temperature in the gas chamber rise sharply.

When the cylinder piston 10 moves to its top dead center position, the position of the piston assembly in the cylinder body 6 is shown in FIG. 4 . The engine completes the work of the first stroke and enters the second stroke. Because there is high-temperature and high-pressure gas in the scavenging chamber 7 at this time, the cylinder piston 10 moves from left to right under the action of high-temperature and high-pressure gas, that is, moves from the top dead center position to the bottom dead center position to perform work externally. Expansion stroke. During the expansion stroke, due to the low pressure in the starting oil chamber 4, the low-pressure accumulator 16 flushes oil into the starting oil chamber 4, and the pump piston 14 passes the high-pressure oil in the pump piston chamber 15 through the port B of the constant power transformer 2 output, since the pressure at port B of constant power transformer 2 is much greater than the pressure at port A of constant power transformer 2 during the expansion stroke, the constant power transformer 2 needs a low-pressure accumulator to supply a certain amount of oil from port C, and the oil is in Its port A concatenates and outputs work to the outside. At this time, the flow direction of the oil is shown by the arrow in Fig. 4 . When the cylinder piston 10 moves to the right to 2/3 of its stroke, the valve 8 is opened, the expansion stroke ends, the exhaust gas in the gas chamber is discharged, the pressure and temperature in the cylinder decrease, and the external air enters the scavenging air through the intake check valve 5 7 and the gas chamber to realize ventilation. When the cylinder piston 10 moves rightward to its bottom dead center position, the second stroke ends, and a working cycle is completed so far, and the heat energy of fuel combustion is converted into hydraulic energy through the piston assembly, stored in the high-pressure accumulator 1 and released to the outside. output work.

Example 2:

The hydraulic free piston engine includes: a high pressure accumulator 1, a low pressure accumulator 16, a constant power transformer 2, a control valve C18, a cylinder block 6, an injector 9 and a piston assembly. Wherein the cylinder block 6 is the body, the high-pressure accumulator 1 and the low-pressure accumulator 16 are energy storage devices, and the piston assembly includes a cylinder piston 10, a piston connecting rod 12 and a pump piston 14 connected in sequence. The constant power transformer 2 has three ports, namely port A, port B and port C.

The overall connection relationship is shown in FIG. 2 , the cylinder body 6 is a hollow cylindrical structure, providing a mounting cavity for the piston assembly. The cylinder block 6 can be divided into three sections in the axial direction according to different diameters. From left to right, there are cylindrical section A, cylindrical section B and cylindrical section C, wherein the diameter of cylindrical section B is larger than that of cylindrical section B. Diameters of segment C and cylindrical segment A. The pump piston 14 is a disc-shaped structure matching the inner diameter of the cylindrical section C, and the cylinder piston 10 is a disc-shaped structure matching the inner diameter of the cylindrical section A. The inner cavity of the cylindrical section C is divided into a chamber A and a chamber B by a partition plate through which only the piston connecting rod 12 passes, and the pump piston 14 is located in the chamber B, and the chamber B is divided into piston oil The chamber 15 and the starting oil chamber 4, wherein the starting oil chamber 4 is the chamber between the partition plate and the pump piston 14. The inner cavity of the cylindrical section A is a scavenging chamber 7 , and a fuel injector 9 and an air valve 8 are arranged on the inner bottom surface corresponding to the scavenging chamber 7 . A hole is opened on the circumferential surface of the chamber A, and an intake check valve 5 is arranged at the opening. The function of the intake check valve 5 is to charge fresh gas into the scavenging chamber 7 . A guide wall 11 for guiding the movement of the cylinder piston 10 is arranged in the cylindrical section B along its axial direction, and a plurality of air holes are processed on the guide wall 11 .

The high-voltage accumulator 1 is connected to the port A of the constant power transformer 2 and the starting oil chamber 4 through two oil circuits; a control valve C17 is set on the oil circuit connected to the starting oil chamber 4 . The control valve C17 is a two-position two-way solenoid valve. When it is in the left position, the high-pressure accumulator 1 communicates with the starting oil chamber 4. When it is in the right position, the low-pressure accumulator 16 communicates with the starting oil chamber 4. . The low-voltage accumulator 16 is connected to the port C of the constant power transformer 2 through an oil circuit; the port B of the constant power transformer 2 is directly connected to the piston oil chamber 15 .

The above-mentioned embodiment 2 is an improved version of embodiment 1. Compared with embodiment 1, a control valve is omitted, which simplifies the operation, and its working principle and process are the same as those of embodiment 1.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (4)

1. A single-piston hydraulic free-piston engine with stepless speed regulation, is characterized in that, comprises: high pressure accumulator (1), low pressure accumulator (16), constant power transformer (2), cylinder body (6) , an injector (9) and a piston assembly; the piston assembly includes a cylinder piston (10), a piston connecting rod (12) and a pump piston (14) connected in sequence; the constant power transformer (2) has three ports , respectively port A, port B and port C; The connection relationship is as follows: the piston assembly is located in the cavity of the cylinder block (6); the cylinder block (6) is divided into three sections along the axial direction according to the diameter of the inner cavity, respectively cylindrical section A and cylindrical section B And cylindrical section C; Wherein the diameter of cylindrical section B is greater than the diameter of cylindrical section A; Described pump piston (14) is the disc structure that matches with the internal diameter of described cylindrical section C; Described cylinder piston ( 10) It is a disc-shaped structure matched with the inner diameter of the cylindrical section A; the inner cavity of the cylindrical section C is divided into chamber A and chamber through a partition that only passes through the piston connecting rod (12) B, the pump piston (14) is located in the chamber B, and the chamber B is divided into a piston oil chamber (15) and a starting oil chamber (4), wherein the starting oil chamber (4) is the separator and The cavity between the pump pistons (14); the inner cavity of the cylindrical section A is the scavenging chamber (7), and the inner bottom surface corresponding to the scavenging chamber (7) is provided with a fuel injector (9) and Air valve (8); an intake check valve (5) is provided on the circumferential surface of the chamber A; Port A of the constant power transformer (2) is connected to the high-voltage accumulator (1) through an oil circuit, port C is connected to the low-pressure accumulator (16) through an oil circuit, and port B is connected to the piston oil chamber through an oil circuit (15) connectivity; In addition, by setting the control valve so that the hydraulic free piston engine is in the starting condition, the high-pressure accumulator (1) communicates with the starting oil chamber (4); during the first stroke and the second stroke, the low-pressure accumulator The energy device (16) communicates with the starting oil chamber (4); the starting condition refers to the process in which the cylinder piston (10) moves from the initial position to its bottom dead center position; the first stroke refers to the cylinder piston (10) moving by The process in which the bottom dead center position moves to its top dead center position, and the second stroke refers to the process in which the cylinder piston (10) moves from the top dead center position to its bottom dead center position; the bottom dead center position refers to the movement of the piston assembly toward The position at which the piston assembly moves to its maximum stroke to the right, and the top dead center position refers to the position at which the piston assembly moves to its maximum stroke to the left. 2. stepless speed regulation single-piston hydraulic free-piston engine as claimed in claim 1, is characterized in that, by arranging control valve A (3) and control valve B (13), make this hydraulic free-piston engine in starting mode , the high-pressure accumulator (1) communicates with the starting oil chamber (4); during the first stroke and the second stroke, the low-pressure accumulator (16) communicates with the starting oil chamber (4); specifically: The high-pressure accumulator (1) is connected to the starting oil chamber (4) through the oil circuit provided with the control valve A (3); the control valve A (3) is a two-position one-way solenoid valve, when it is in the left , the high-pressure accumulator (1) communicates with the starting oil chamber (4), and when it is in the right position, the oil circuit is cut off; the control valve B (13) is a two-position two-way solenoid valve. When it is in the upper position, the low-pressure accumulator (16) communicates with the starting oil chamber (4); when it is in the lower position, the low-pressure accumulator (16) communicates with the piston oil chamber (15). 3. stepless speed regulation single-piston hydraulic free-piston engine as claimed in claim 1, is characterized in that, by arranging control valve C (18) to make this hydraulic free-piston engine when starting working condition, high-pressure accumulator ( 1) communicate with the starting oil chamber (4); during the first stroke and the second stroke, the low-pressure accumulator (16) communicates with the starting oil chamber (4); specifically: The high-pressure accumulator (1) is connected to the starting oil chamber (4) through the oil passage provided with the control valve C (18); the control valve C (18) is a two-position two-way solenoid valve, When it is in the right position, the high-pressure accumulator (1) communicates with the starting oil chamber (4), and when it is in the right position, the low-pressure accumulator (16) communicates with the starting oil chamber (4). 4. The continuously variable speed single-piston hydraulic free-piston engine as claimed in claim 1, 2 or 3, characterized in that, in the cylindrical section B, along its axial direction, there is a cylinder piston (10) The movement of the guide wall (11) plays a guiding role; more than two air holes are arranged on the circumferential surface of the guide wall (11).