An electromagnetic spring stirling generator

Abstract

The application discloses an electromagnetic spring Stirling generator, which comprises a Stirling generator body, an electromagnetic spring and a control system, wherein the Stirling generator body is connected with the electromagnetic spring, and the electromagnetic spring is connected with the control system; the Stirling generator body comprises a gas distribution piston and a power piston; the electromagnetic spring comprises a first linear motor, a second linear motor, an energy storage device, a bidirectional converter and a frequency converter; the energy storage device is connected with the first linear motor through the bidirectional converter; the first linear motor is connected with the frequency converter; and the frequency converter is connected with the second linear motor; the first linear motor is connected with the power piston; and the second linear motor is connected with the gas distribution piston. The electromagnetic spring is used to replace the plate spring component of the traditional Stirling generator, so that the fatigue fracture problem of the plate spring of the traditional Stirling generator is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to a Stirling generator, in particular to an electromagnetic spring Stirling generator. BACKGROUND

[0002] The Stirling generator is a closed cycle external combustion generator relying on the thermal expansion and contraction of high-pressure gas to push the piston to move and generate electricity. The heating end of the Stirling generator absorbs heat, pushes the piston to move in the form of pressure wave, and releases excess heat through the cold end. The Stirling generator completes a Stirling cycle through four processes: isothermal compression, constant volume heating, isothermal expansion, and constant volume cooling.

[0003] The common Stirling generators at present mainly include crank connecting rod type and free piston type. The crank connecting rod type Stirling generator has a short continuous running time due to the problems of piston lateral force and dynamic sealing. The free piston type Stirling generator has a more compact structure and no dynamic sealing problem, so it has higher reliability, longer service life and smaller noise, and has great application potential in the fields of power generation in extreme environment, deep space exploration, underwater power and the like. The free piston type Stirling generator mainly consists of a heater, a regenerator, a cooler, a piston, a plate spring and other key components. The piston and the plate spring together form a vibration system, which resonates with the gas wave generated by the heat exchange system to output power externally. The operating frequency of the Stirling generator is relatively high, and as the power of the generator increases, the rebound force borne by the plate spring also increases, which leads to fatigue fracture problem, seriously affecting the service life of the generator.

[0004] The traditional free piston type Stirling generator has a linear motor mover fixed on the power piston, and the mover reciprocates with the piston to convert mechanical energy into electrical energy. At the same time, the gas distribution piston constitutes a vibration system by connecting with the plate spring, and the plate spring provides rebound force for the gas distribution piston to complete the gas distribution process. Therefore, the traditional free piston type Stirling generator realizes power output by the vibration system composed of the plate spring and the piston, and the vibration frequency can reach more than 30 Hz. The plate spring is generally made of metal materials such as silicon manganese steel and carbon steel, which has good axial stiffness and radial support. However, as the power of the Stirling generator increases, the working frequency and movement stroke of the plate spring also increase, and the possibility of fatigue fracture of the plate spring increases. Once the plate spring has fatigue characteristics, the Stirling generator will stop running and the service life will end. SUMMARY

[0005] The technical problem to be solved by the present application is to overcome the shortcomings of the above background technology, and to provide an electromagnetic spring Stirling generator which uses an electromagnetic spring to replace the plate spring component of the traditional Stirling generator, thereby solving the problem of fatigue fracture of the plate spring of the traditional Stirling generator.

[0006] The technical scheme adopted by the present application to solve its technical problems is that a kind of electromagnetic spring stirling generator, including stirling generator body, still including electromagnetic spring and control system, stirling generator body is connected with electromagnetic spring, electromagnetic spring is connected with control system;The stirling generator body includes gas distribution piston and power piston, the electromagnetic spring includes first linear motor, second linear motor, energy storage device, bidirectional converter and frequency converter, energy storage device is connected to first linear motor by bidirectional converter, first linear motor is connected with frequency converter, frequency converter is connected with second linear motor;First linear motor is connected with power piston, and second linear motor is connected with gas distribution piston.

[0007] Further, the stirling generator body includes a heater, a regenerator, a cooler, a gas distribution piston, a power piston, a cylinder, and a housing. The cylinder is arranged in the housing. The heater, the regenerator, and the cooler are sequentially arranged from top to bottom between the cylinder and the housing. The gas distribution piston and the power piston are sequentially arranged in the cylinder from top to bottom. The lower end of the gas distribution piston is provided with a connecting rod. The power piston is sleeved on the middle part of the connecting rod. The space formed between the gas distribution piston and the housing is an expansion chamber. The space formed between the gas distribution piston and the power piston is a compression chamber. The space formed between the power piston and the housing is a back pressure chamber.

[0008] Further, the first linear motor includes a first linear motor stator and a first linear motor mover. The first linear motor stator is installed on the housing through a fixing frame. The first linear motor mover is sleeved on the outside of the power piston. The second linear motor includes a second linear motor stator and a second linear motor mover. The second linear motor stator is installed on the housing through a fixing frame. The second linear motor mover is sleeved on the lower part of the connecting rod of the gas distribution piston.

[0009] Further, the second linear motor is installed in the back pressure chamber.

[0010] Further, the type of the first linear motor is a cylindrical permanent magnet linear motor with a moving magnet structure. The type of the second linear motor is a cylindrical permanent magnet linear motor with a moving magnet structure.

[0011] Further, the electromagnetic spring further includes an inductor and a capacitor. The frequency converter is connected with the second linear motor through an LC filter circuit composed of the inductor and the capacitor.

[0012] Further, the control system comprises sensors and a controller, the sensors are connected with the first linear motor and the second linear motor, and are used for collecting output signals of the first linear motor and the second linear motor and inputting the collected signals into the controller; the controller comprises a DSP control module, the DSP control module is provided with a phase shift algorithm control program, the controller processes the signals collected by the sensors, compares the phase difference between the output signals of the first linear motor and the second linear motor, the DSP control module executes the phase shift algorithm control program according to the phase difference between the output signals of the first linear motor and the second linear motor, generates a PWM control signal, and then sends the generated PWM control signal back to the switching device of the frequency converter, so as to control the frequency converter to adjust the phase of the output signal of the first linear motor, so that the phase difference between the output signals of the first linear motor and the second linear motor exists and is less than 90°.

[0013] Further, the gap between the gas distribution piston and the inner wall of the cylinder is at most 0.1 mm.

[0014] Further, the gap between the power piston and the inner wall of the cylinder is at most 0.04 mm.

[0015] Further, the gap between the power piston and the outer wall of the connecting rod of the gas distribution piston is at most 0.04 mm.

[0016] Compared with the prior art, the application has the following advantages:

[0017] (1) The electromagnetic spring is used to replace the plate spring part of the traditional Stirling generator, so that the problem of fatigue fracture of the plate spring of the traditional Stirling generator is solved.

[0018] (2) The energy storage device and the bidirectional converter are used to realize the starting of the electromagnetic spring Stirling generator and the charging of the excess electric energy, and the starting mode is flexible and reliable.

[0019] (3) The phase difference between the gas distribution piston and the power piston is regulated and controlled through the frequency converter and the control system, so that the power regulation of the Stirling generator during operation is realized. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structural schematic diagram of an embodiment of the application.

[0021] In the figure, 1 is a heater, 2 is a regenerator, 3 is a cooler, 4 is a gas distribution piston, 5 is a power piston, 6 is a cylinder, 7 is a first linear motor stator, 8 is a first linear motor rotor, 9 is a second linear motor stator, 10 is a second linear motor rotor, 11 is an expansion chamber, 12 is a compression chamber, 13 is a back pressure chamber, 14 is a controller, 15 is a frequency converter, 16 is an inductor, 17 is a capacitor, 18 is a line, 19 is a sensor, 20 is an energy storage device, and 21 is a bidirectional converter. DETAILED DESCRIPTION

[0022] The application will be described in further detail below with reference to the drawings and specific embodiments.

[0023] In view of the fatigue fracture problem of the plate spring of the existing free-piston Stirling generator, the application provides an electromagnetic spring Stirling generator. The electromagnetic spring is used as the gas distribution piston resonance system and the power piston resonance system of the free-piston Stirling generator, and there is no plate spring component, so that the service life of the Stirling generator can be greatly improved, and the application value is excellent.

[0024] With reference to Figure 1 The embodiment includes a Stirling generator body, an electromagnetic spring and a control system, the Stirling generator body is connected with the electromagnetic spring, and the electromagnetic spring is connected with the control system.

[0025] The Stirling generator body includes a heater 1, a regenerator 2, a cooler 3, a gas distribution piston 4, a power piston 5, a cylinder 6 and a shell, the cylinder 6 is arranged in the shell, and the heater 1, the regenerator 2 and the cooler 3 are sequentially arranged from top to bottom between the cylinder 6 and the shell, the gas distribution piston 4 and the power piston 5 are sequentially arranged in the cylinder 6 from top to bottom, a connecting rod is arranged at the lower end of the gas distribution piston 4, the power piston 5 is sleeved on the middle part of the connecting rod, a space formed between the gas distribution piston 4 and the shell is an expansion chamber 11, a space formed between the gas distribution piston 4 and the power piston 5 is a compression chamber 12, and a space formed between the power piston 5 and the shell is a back pressure chamber 13.

[0026] The electromagnetic spring includes a first linear motor, a second linear motor, an energy storage device 20, a bidirectional converter 21, a frequency converter 15, an inductor 16, a capacitor 17 and a line 18. The energy storage device 20 can use a lead-acid storage battery or a lithium ion battery, the energy storage device 20 is connected to the first linear motor through the bidirectional converter 21, is responsible for starting the Stirling generator, and can store the electric energy generated by the generator. The first linear motor is connected with the frequency converter 15, the frequency converter 15 is connected with the second linear motor through an LC filter circuit composed of the inductor 16 and the capacitor 17. The components are connected through the line 18.

[0027] The frequency converter 15 adopts a full-control type device, can control the phase of the output electric energy of the first linear motor, and is connected to the second linear motor. The LC filter circuit can filter the high-frequency noise in the wave form generated by the frequency converter 15, improve the wave form quality, and avoid overheating or irregular vibration of the second linear motor.

[0028] The first linear motor is connected with the power piston 5, and the first linear motor comprises a first linear motor stator 7 and a first linear motor mover 8. The first linear motor stator 7 is installed on the shell through a fixing frame, and the first linear motor mover 8 is sleeved outside the power piston 5, so as to easily ensure the coaxial degree of the power piston 5 and the first linear motor mover 8, save the internal space of the Stirling generator, and reduce the overall volume of the Stirling generator. The type of the first linear motor is a cylindrical permanent magnet linear motor with a moving-magnetic structure. The second linear motor is connected with the gas distribution piston 4, and the second linear motor comprises a second linear motor stator 9 and a second linear motor mover 10. The second linear motor stator 9 is installed on the shell through a fixing frame, and the second linear motor mover 10 is sleeved below the connecting rod of the gas distribution piston 4. The type of the second linear motor is a cylindrical permanent magnet linear motor with a moving-magnetic structure. The second linear motor is installed in the back pressure cavity 13.

[0029] When the linear motor is fixed, the motor magnetic circuit center needs to be coaxial with the piston, so as to ensure the piston air tightness and frictionless. The linear motor mover is adsorbed at the motor center balance position due to the positioning torque, and resists the movement of the mover. Since the second linear motor is installed in the back pressure cavity 13 and is far away from the heating end, the phenomenon of permanent magnet demagnetization of the motor due to high temperature is avoided.

[0030] The gas distribution piston 4 is responsible for pushing the working gas to continuously circulate and exchange in the expansion cavity 11 and the compression cavity 12, so as to realize the heating or cooling of the working medium, cause the thermal expansion and cold contraction of the working gas, and thus generate a pressure wave. The power piston 5 reciprocates under the influence of the pressure wave in the expansion cavity 11 and the compression cavity 12, so as to complete the conversion from heat energy to mechanical energy. When the gas distribution piston 4 is installed, a gap of at most 0.1 mm between the gas distribution piston 4 and the inner wall of the cylinder 6 needs to be ensured. Meanwhile, when the power piston 5 is installed, a gap of at most 0.04 mm between the power piston 5 and the inner wall of the cylinder 6 needs to be ensured, and a gap of at most 0.04 mm between the power piston 5 and the outer wall of the connecting rod of the gas distribution piston 4 needs to be ensured.

[0031] The control system comprises the sensor 19 connected with the first linear motor and the second linear motor and the controller 14, the sensor 19 is used for collecting the output signals of the first linear motor and the second linear motor and inputting the collected signals into the controller 14, the controller 14 comprises a DSP control module, the DSP control module is provided with a phase shift algorithm control program, the controller 14 processes the signals collected by the sensor 19, compares the phase difference between the output signals of the first linear motor and the second linear motor, the DSP control module executes the phase shift algorithm control program according to the phase difference between the output signals of the first linear motor and the second linear motor, generates a PWM control signal, and then sends the generated PWM control signal back to the switching device of the frequency converter 15, so as to control the frequency converter 15 to adjust the phase of the output signal of the second linear motor, so that the phase difference between the output signals of the first linear motor and the second linear motor exists and is less than 90°. In the embodiment, the phase shift algorithm control program is an existing program.

[0032] The electromagnetic spring Stirling generator is started by the energy storage device 20 and the bidirectional converter 21. In the initial state, the bidirectional converter 21 converts the electrical energy stored in the energy storage device 20 into single-phase alternating current and inputs the single-phase alternating current into the first linear motor. After the periodic oscillation of the first linear motor, the Stirling generator is started. The first linear motor is provided with alternating current in the opposite direction of displacement to provide rebound force for the power piston 5, and the second linear motor is provided with alternating current in the opposite direction of displacement to provide rebound force for the gas distribution piston 4. After the Stirling generator is started, there is a phase difference between the power piston and the gas distribution piston, which is generally less than 90°. In the traditional Stirling generator with a plate spring as an elastic element, the phase difference between the power piston and the gas distribution piston is related to the initial design of the Stirling generator, such as the stiffness of the plate spring and the volume of the working chamber, and is also related to the running state, such as the heating end temperature and the cooling end temperature. In short, the phase difference is difficult to adjust. However, in the electromagnetic spring Stirling generator, after the first linear motor outputs single-phase alternating current due to the approximate sinusoidal motion of the power piston 5, the phase of the single-phase alternating current can be adjusted by the frequency converter 15 and then input into the second linear motor of the gas distribution piston 4. The second linear motor is subjected to alternating current in the opposite direction of displacement to provide rebound force for the gas distribution piston 4. At the same time, the sinusoidal motion of the gas distribution piston 4 generates an approximately sinusoidal gas wave, and the limiting effect of the frequency converter 15 on the first linear motor makes the mover of the first linear motor receive rebound force when moving to the far end, thereby driving the power piston 5 to move. After this method is adopted, the phase difference between the power piston 5 and the gas distribution piston 4 can be controlled, and the power regulation of the Stirling generator during operation is realized.

[0033] At the same time, during the normal operation of the electromagnetic spring Stirling generator, only the piston and the mover are subjected to the action of the gas wave force and the electromagnetic force, and there is no deformed component, so the service life of the Stirling generator is greatly prolonged. At the same time, the first linear motor is installed in the compression cavity 12, and the second linear motor is installed in the back pressure cavity 13, both of which are far away from the high temperature zone, so there is no high temperature demagnetization, and the reliability of the linear motor is improved.

[0034] The electromagnetic spring Stirling generator is started by the energy storage device and the bidirectional converter 21. In the initial state, the bidirectional converter 21 converts the electrical energy stored in the energy storage device 20 into single-phase alternating current, and then connects the first linear motor. The first linear motor drives the power piston 5 to move upward first, compressing the working gas in the cylinder 6. After the working gas is extruded, the pressure increases, thereby driving the gas distribution piston 4 to move downward. When the gas distribution piston 4 moves downward, the working gas in the compression cavity 12 is extruded into the inside of the cooler 3, and then flows through the regenerator 2 and the heater 1 to absorb heat, and finally enters the inside of the expansion cavity 11. Then the first linear motor drives the power piston 5 to move downward, the volume of the working gas in the cylinder 6 becomes larger, and the pressure becomes smaller, thereby the pressure of the back pressure cavity 13 drives the gas distribution piston 4 to move upward. When the gas distribution piston 4 moves upward, the working gas in the expansion cavity 11 is extruded into the inside of the heater 2, and then flows through the regenerator 2 and the cooler 3 to release heat, and finally enters the compression cavity 12. In this way, a complete working gas circulation process is completed. After the first linear motor oscillates periodically, the stroke of the gas distribution piston 4 reaches the rated range, and has sufficient gas distribution capacity, so the Stirling generator is successfully started, and after starting, the power piston linear motor is switched from the motor mode to the generator mode.

[0035] After the electromagnetic spring Stirling generator is started, the first linear motor is switched to the generator mode. When the gas distribution piston 4 moves upward, the working gas in the expansion cavity 11 is extruded into the heater 1, and then flows through the regenerator 2 and the cooler 3, and then flows into the compression cavity 12 after the temperature of the gas decreases, at this time, the pressure in the cylinder 6 decreases, and the power piston 5 is driven by the pressure of the back pressure cavity 13 to move upward. When the gas distribution piston 4 moves downward, the working gas in the compression cavity 12 is extruded into the cooler 3, and then flows through the regenerator 2 and the heater 1, and then flows into the expansion cavity 11 after the temperature of the gas rises, at this time, the pressure in the cylinder increases, and the power piston 5 is driven by the pressure in the cylinder to move downward. In this way, a complete Stirling cycle work process is completed.

[0036] In this embodiment, the working gas is helium.

[0037] The application provides an electromagnetic spring Stirling generator, which uses an electromagnetic spring to replace a plate spring component of a traditional Stirling generator; an energy storage device 20 is used in cooperation with a bidirectional converter 21 to realize starting of the electromagnetic spring Stirling generator and charging of redundant electric energy; electric energy output by a first linear motor is adjusted in phase by a frequency converter 15, and then is transmitted to a second linear motor after LC filtering, so that phase difference of a gas distribution piston 4 and a power piston 5 is regulated.

[0038] Various modifications and variations to the application can be carried out by those skilled in the art, which do not depart from the scope of the application as defined by the claims and their equivalents.

[0039] The contents not described in detail in the specification are prior art known to those skilled in the art.

Claims

1. An electromagnetic spring Stirling generator comprising a Stirling generator body, characterised in that: The Stirling generator body is connected with the electromagnetic spring, and the electromagnetic spring is connected with the control system; the Stirling generator body comprises a gas distribution piston and a power piston; the electromagnetic spring comprises a first linear motor, a second linear motor, an energy storage device, a bidirectional converter and a frequency converter; the energy storage device is connected to the first linear motor through the bidirectional converter; the first linear motor is connected with the frequency converter; the frequency converter is connected with the second linear motor; the first linear motor is connected with the power piston; the second linear motor is connected with the gas distribution piston; the control system comprises a sensor and a controller; the sensor is connected with the first linear motor and the second linear motor, and is used for collecting output signals of the first linear motor and the second linear motor and inputting the collected signals into the controller; the controller comprises a DSP control module; the DSP control module is provided with a phase shift algorithm control program; the controller processes the signals collected by the sensor, compares the phase difference between the output signals of the first linear motor and the second linear motor, and executes the phase shift algorithm control program according to the phase difference between the output signals of the first linear motor and the second linear motor to generate a PWM control signal, which is then sent back to the switching device of the frequency converter to control the frequency converter to adjust the phase of the output signal of the first linear motor, so that the phase difference between the output signals of the first linear motor and the second linear motor is less than 90°.

2. The electromagnetic spring Stirling generator of claim 1, wherein: The Stirling generator body comprises a heater, a regenerator, a cooler, a gas distribution piston, a power piston, a cylinder and a shell; the cylinder is arranged in the shell; the heater, the regenerator and the cooler are sequentially arranged from top to bottom between the cylinder and the shell; the gas distribution piston and the power piston are sequentially arranged in the cylinder from top to bottom; the lower end of the gas distribution piston is provided with a connecting rod; the power piston is sleeved on the middle part of the connecting rod; a space formed between the gas distribution piston and the shell is an expansion chamber; a space formed between the gas distribution piston and the power piston is a compression chamber; a space formed between the power piston and the shell is a back pressure chamber.

3. The electromagnetic spring Stirling generator of claim 2, wherein: The first linear motor comprises a first linear motor stator and a first linear motor rotor; the first linear motor stator is mounted on the shell through a fixing frame; the first linear motor rotor is sleeved on the outside of the power piston; the second linear motor comprises a second linear motor stator and a second linear motor rotor; the second linear motor stator is mounted on the shell through a fixing frame; the second linear motor rotor is sleeved on the lower part of the connecting rod of the gas distribution piston.

4. The electromagnetic spring Stirling generator of claim 2, wherein: The second linear motor is arranged in the back pressure chamber.

5. The electromagnetic spring Stirling generator of claim 1 or 2, wherein: The first linear motor is a cylindrical permanent magnet linear motor with a moving magnet structure; the second linear motor is a cylindrical permanent magnet linear motor with a moving magnet structure.

6. The electromagnetic spring Stirling generator of claim 1 or 2, wherein: The electromagnetic spring further comprises an inductor and a capacitor; the frequency converter is connected with the second linear motor through an LC filter circuit composed of the inductor and the capacitor.

7. The electromagnetic spring Stirling generator of claim 2, wherein: The gap between the gas distribution piston and the inner wall of the cylinder is at most 0.1 mm.

8. The electromagnetic spring Stirling generator of claim 2, wherein: The gap between the power piston and the inner wall of the cylinder is at most 0.04 mm.

9. The electromagnetic spring Stirling generator of claim 2, wherein: The gap between the power piston and the outer wall of the connecting rod of the gas distribution piston is at most 0.04 mm.

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