A Stirling generator with a variable stiffness electromagnetic spring device

Abstract

A Stirling generator with a variable-stiffness electromagnetic spring device includes a regenerator, a gas distribution piston, a moving piston, a cylinder, a linear motor, an electromagnetic spring device, a gas distribution piston leaf spring, and a housing. The cylinder is disposed within the housing, the regenerator is disposed between the cylinder and the housing, the gas distribution piston and the moving piston are disposed within the cylinder in order from top to bottom, a connecting rod is disposed at the lower end of the gas distribution piston, the moving piston is sleeved in the middle of the connecting rod, the space formed between the gas distribution piston and the housing is an expansion chamber, and the space formed between the gas distribution piston and the moving piston is a compression chamber, the linear motor is disposed on the connecting rod, the moving piston is connected to the linear motor, and the electromagnetic spring device is disposed at both ends of the linear motor; the gas distribution piston leaf spring is disposed at the lower end of the connecting rod, and the gas distribution piston leaf spring is connected to the connecting rod. This invention can significantly improve accuracy and adaptability, enable long-term stable operation, and increase the operating life of the generator.

Description

Technical Field

[0001] The present invention relates to a Stirling generator, in particular to a Stirling generator with a variable stiffness electromagnetic spring device. Background Art

[0002] With the continuous development of aerospace technology in recent years, countries around the world have launched deep space exploration activities. Stirling power generation systems have attracted attention from various countries due to their high efficiency, strong adaptability, high thermal energy conversion efficiency, compact structure, long life, and high reliability.

[0003] Existing Stirling generators mostly use mechanical leaf springs at the moving end, which have high requirements for materials and assembly. The structure of mechanical leaf springs is relatively complex, and stainless steel is usually used for wire cutting to make the moving leaf springs. At the same time, mechanical fatigue during long-term operation may cause damage to the device or even damage to the mechanical structure, which in turn affects the stable operation of the power generation system and is difficult to adapt to the operating environment of space power supplies. At the same time, mechanical leaf springs require auxiliary components such as mechanical connecting rods to connect moving terminals and linear motors and other components, and the assembly accuracy of the corresponding parts is extremely high. During the assembly process, a variety of high-precision instruments are required to correct the position to meet the accuracy requirements. Insufficient assembly accuracy may cause misalignment of the power connection components, thereby increasing losses during operation and reducing the operating efficiency of the power generation system.

[0004] The complex processing methods for stainless steel leaf springs lead to high costs and high prices. Due to the inherent properties of stainless steel, the thickness and volume of leaf springs are inevitably limited to meet the design parameters of the Stirling generator, such as stiffness and resonant frequency. This increases the complexity of the internal mechanical structure of the Stirling generator and hinders assembly. Stainless steel leaf springs can experience elastic degradation during long-term operation, which reduces stiffness, leading to displacement of the moving terminals and reduced amplitude, reducing the output efficiency of the Stirling generator. Stainless steel is relatively fragile and prone to mechanical fatigue and fracture during operation, reducing the reliability of the Stirling generator. In severe cases, the entire leaf spring may break, shortening its lifespan. The spring force of stainless steel leaf springs is affected by factors such as ambient temperature, and their poor spring force and dynamic response make them difficult to adapt to Stirling generators operating in diverse environments and with varying technical specifications. The low reliability of stainless steel leaf springs requires regular replacement and maintenance, increasing the maintenance cost of the Stirling generator. The compact and complex internal structure and high assembly precision requirements of the Stirling generator further increase this cost. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the above-mentioned background technology and provide a Stirling generator with a variable stiffness electromagnetic spring device, which can greatly improve the accuracy and adaptability, can operate stably for a long time, and increase the service life of the generator.

[0006] The technical solution adopted by the present invention to solve its technical problems is a Stirling generator with a variable stiffness electromagnetic spring device, including a regenerator, a gas distribution piston, a moving piston, a cylinder, a linear motor, an electromagnetic spring device, a gas distribution piston leaf spring and a shell. The cylinder is arranged in the shell, the regenerator is arranged between the cylinder and the shell, the gas distribution piston and the moving piston are arranged in the cylinder from top to bottom in sequence, a connecting rod is provided at the lower end of the gas distribution piston, and the moving piston is sleeved in the middle of the connecting rod. The space formed between the gas distribution piston and the shell is an expansion chamber, and the space formed between the gas distribution piston and the moving piston is a compression chamber. The linear motor is arranged on the connecting rod, the moving piston is connected to the linear motor, and the electromagnetic spring device is arranged at both ends of the linear motor; the gas distribution piston leaf spring is arranged at the lower end of the connecting rod, and the gas distribution piston leaf spring is connected to the connecting rod.

[0007] Furthermore, the electromagnetic spring device includes a first electromagnetic spring and a second electromagnetic spring. The first electromagnetic spring is arranged at the upper end of the linear motor, and the second electromagnetic spring is arranged at the lower end of the linear motor. The first electromagnetic spring includes an electromagnetic spring wire hoop, an excitation coil and a magnetic isolation ring. The electromagnetic spring wire hoop is an annular structure as a whole, and the cross-section is a U-shaped groove structure. The excitation coil is wound in the annular U-shaped groove. The magnetic isolation ring is an annular structure and is arranged on one side of the electromagnetic spring wire hoop. The structure of the second electromagnetic spring is the same as that of the first electromagnetic spring. The first electromagnetic spring is connected to the upper end of the linear motor through the magnetic isolation ring, and the second electromagnetic spring is connected to the lower end of the linear motor through the magnetic isolation ring.

[0008] Furthermore, the linear motor includes a permanent magnet, a stator coil, a magnet support frame, a stator yoke, a stator fixing frame and a moving piston fixing frame. The permanent magnet is composed of multiple groups of permanent magnet sheets with opposite polarities arranged along the outer wall of the magnet support frame. The permanent magnet is arranged on the outer surface of the moving piston fixing frame. The moving piston is connected to the permanent magnet through the moving piston fixing frame to drive the permanent magnet to move; the lower part of the moving piston fixing frame is connected to the magnet support frame, and the upper part of the power piston fixing frame is connected to the moving piston; the stator yoke is composed of a stack of C-shaped silicon steel sheets that are symmetrical up and down, and the stator coil is wound inside the stator yoke; the stator fixing frame is connected to the stator yoke inside.

[0009] Furthermore, the first electromagnetic spring is connected to the upper surface of the stator fixing frame through a magnetic isolation ring, and the second electromagnetic spring is connected to the lower surface of the stator fixing frame through a magnetic isolation ring.

[0010] Furthermore, the excitation coil is an enameled coil with 200 turns.

[0011] Furthermore, the stator coils are two groups of 400-turn enameled coils.

[0012] Furthermore, the stator fixing frame is formed by connecting two upper and lower circular stainless steel rings with multiple stainless steel columns, and the overall structure is a cage-like structure, and multiple threaded holes are opened on the upper and lower rings.

[0013] Compared with the prior art, the advantages of the present invention are as follows:

[0014] (1) The electromagnetic spring device with variable stiffness of the present invention can rely on the electromagnetic coil to provide elastic force for the moving piston and provide radial support for the moving end of the Stirling generator. Compared with the traditional leaf spring structure, it can greatly improve the accuracy and adaptability, can operate stably for a long time, and increase the service life of the generator. The electromagnetic spring device has a longer service life than the traditional leaf spring and can reduce the increase in cost caused by the increase in maintenance times.

[0015] (2) The present invention can change the stiffness of the electromagnetic spring device by adjusting the excitation current of the electromagnetic spring device, thereby improving the energy conversion efficiency of the generator and enabling the Stirling power generation system to adapt to different workloads and working conditions.

[0016] (3) The present invention optimizes the overall structure of the Stirling generator. Compared with the traditional leaf spring, the electromagnetic spring device has a smaller volume and lighter weight, making the spatial structure of the Stirling generator more compact. This feature has great advantages in the application of the Stirling generator system in space power supply, underwater ship power supply system, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of a Stirling generator embodiment of the present invention.

[0018] Figure 2 yes Figure 1 A schematic structural diagram of the electromagnetic spring device of the illustrated embodiment.

[0019] Figure 3 yes Figure 1 A cross-sectional view of the electromagnetic spring device of the illustrated embodiment.

[0020] Figure 4 yes Figure 1 A schematic structural diagram of a linear motor equipped with an electromagnetic spring device in the illustrated embodiment.

[0021] Figure 5 yes Figure 1 Schematic diagram of the working magnetic field of the embodiment shown.

[0022] In the figure, 1 is an electromagnetic spring device, 2 is a linear motor, 3 is a moving piston, 5 is a housing, 6 is a connecting rod, 7 is a gas distribution piston, 8 is a regenerator, 9 is an expansion chamber, 10 is a compression chamber, 11 is a cylinder, 12 is an excitation coil, 13 is a magnetic isolation ring, 14 is a permanent magnet, 15 is a stator coil, 16 is a magnet support frame, 17 is a stator yoke, 18 is a stator fixing frame, 19 is a moving piston fixing frame, and 20 is an electromagnetic spring wire clamp. DETAILED DESCRIPTION

[0023] The present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0024] Reference Figure 1 The Stirling generator of the present invention includes a regenerator 8, a distribution piston 7, a moving piston 3, a cylinder 11, a linear motor 2, an electromagnetic spring device 1, a distribution piston leaf spring (not shown in the figure) and a shell 5. The cylinder 11 is arranged in the shell 5, the regenerator 8 is arranged between the cylinder 11 and the shell 5, the distribution piston 7 and the moving piston 3 are arranged in the cylinder 11 from top to bottom, the lower end of the distribution piston 7 is provided with a connecting rod 6, the moving piston is sleeved in the middle of the connecting rod 6, the space formed between the distribution piston 7 and the shell 5 is an expansion chamber 9, and the space formed between the distribution piston 7 and the moving piston 3 is a compression chamber 10, the linear motor 2 is arranged on the connecting rod 6, the moving piston 3 is connected to the linear motor 2, and the electromagnetic spring device 1 is arranged at both ends of the linear motor 2; the distribution piston leaf spring is arranged at the lower end of the connecting rod 6, and the distribution piston leaf spring is connected to the connecting rod 6.

[0025] Reference Figure 4 The linear motor 2 includes a permanent magnet 14, a stator coil 15, a magnet support frame 16, a stator yoke 17, a stator fixing frame 18 and a moving piston fixing frame 19. The permanent magnet 14 is composed of multiple groups of permanent magnet pieces with opposite polarities, which are arranged along the outer wall of the magnet support frame 16. The permanent magnet 14 is arranged on the outer surface of the moving piston fixing frame 19. The moving piston 3 is connected to the permanent magnet 14 through the moving piston fixing frame 19 to drive the permanent magnet 14 to move; the magnet support frame 16 is in the shape of a water cup, with a hole in the center of the bottom and threaded holes around the hole; the lower part of the moving piston fixing frame 19 is screwed The perforations are connected to the magnet support frame 16, and the upper part of the power piston fixing frame 19 is connected to the moving piston 3 by screws. A small hole is opened in the center of the power piston fixing frame 19; the stator yoke 17 is composed of 12 groups of symmetrical C-shaped silicon steel sheets stacked up and down, and the stator coil 15 is wound inside the stator yoke 17; the stator coil 15 is two groups of 400-turn enameled coils; the stator fixing frame 18 is composed of two upper and lower circular stainless steel rings connected with 12 stainless steel columns, and the overall structure is cage-shaped, with multiple threaded holes opened on the upper and lower rings, and the stator fixing frame 18 is connected to the stator yoke 17 inside.

[0026] Reference Figure 2 、 Figure 3The electromagnetic spring device 1 includes a first electromagnetic spring and a second electromagnetic spring. The first electromagnetic spring is arranged at the upper end of the linear motor 2, and the second electromagnetic spring is arranged at the lower end of the linear motor 2. The first electromagnetic spring includes an electromagnetic spring wire hoop 20, an excitation coil 12, and a magnetic isolation ring 13. The electromagnetic spring wire hoop 20 is an annular structure as a whole, and the cross-section is a U-shaped groove structure. The excitation coil 12 is wound in the annular U-shaped groove. The excitation coil 12 is a 200-turn enameled coil. The excitation coil 12 is used to generate electromagnetic elastic force when current is applied. The magnetic isolation ring 13 is an annular structure. The magnetic isolation ring 13 is arranged on one side of the electromagnetic spring wire hoop 20. The magnetic isolation ring 13 is made of magnetic-resistive material, which isolates the magnetic field and reduces the mutual interference of the magnetic field between the stator coil 15 and the electromagnetic spring device 1. The second electromagnetic spring has the same structure as the first electromagnetic spring. The first electromagnetic spring is connected to the upper surface of the stator mounting bracket 18 via a magnetic isolation ring 13, while the second electromagnetic spring is connected to the lower surface of the stator mounting bracket 18 via a magnetic isolation ring 13. The first electromagnetic spring is connected to the cylinder 11, while the second electromagnetic spring is connected to the connecting rod 6. A preset DC current flows through the excitation coil 12.

[0027] The distribution piston 7, the moving piston 3, the connecting rod 6 and the cylinder 11 together constitute the heat engine part of the Stirling generator, and the linear motor 2 is the generator part of the Stirling generator.

[0028] The working process of this embodiment is:

[0029] The working fluid gas is heated in the expansion chamber 9 and cooled in the compression chamber 10, flows through the regenerator 8, and in this process pushes the gas distribution piston 7 and the moving piston 3. The gas distribution piston 7 reciprocates under the combined action of the gas force and the gas distribution piston leaf spring connected to the connecting rod 6. The moving piston 3 reciprocates under the action of the gas distribution piston 7, the electromagnetic spring device 1 and the linear motor 2. In this process, the permanent magnet 14 connected to the moving piston 3 moves in the linear motor 2, thereby generating an induced electromotive force in the linear motor 2.

[0030] The heat engine operates in a partial cycle, as follows: The working gas in the Stirling generator undergoes isothermal compression, reducing its volume. At this point, the valve piston 7 is stationary at top dead center, while the moving piston 3 gradually moves toward the regenerator 8, reducing the volume of the working chamber. The internal energy of the working gas remains constant, but its pressure increases. Subsequently, the working gas undergoes isochoric heat absorption, increasing its pressure while maintaining its volume. At this point, the total volume of the working chamber remains constant, while the two pistons move together in separate directions: the moving piston 3 moves toward the regenerator 8, while the valve piston 7 moves away from it. At the same time, the working gas flows from the compression chamber 10 through the regenerator 8, absorbing heat from the regenerator 8 packing and entering the expansion chamber 9, causing its temperature to rise and its internal energy to increase. The working gas then undergoes isothermal expansion, increasing its volume and decreasing its pressure. At this point, the distribution piston 7 remains stationary, while the moving piston 3 moves away from the regenerator 8. The gas expands in the expansion chamber 9, increasing the volume of the working chamber while maintaining its internal energy and decreasing its pressure. During this process, the gas performs external work. Finally, the gas releases heat isochorically, decreasing its pressure but maintaining its volume. At this point, the two pistons move synchronously again, with the moving piston 3 continuing to move away from the cold end of the regenerator 8 and the distribution piston 7 moving toward the hot end. This keeps the total volume of the working chamber constant. Simultaneously, the working gas flows from the expansion chamber 9 through the regenerator 8, releasing heat to the regenerator 8 packing and entering the compression chamber 10, causing its temperature to decrease and its internal energy to decrease.

[0031] The operation of the heat engine will drive the moving piston 3 to perform reciprocating sinusoidal motion in the radial direction of the cylinder 11. At this time, the permanent magnet 14 connected to the moving piston 3 will perform reciprocating sinusoidal motion in the stator fixing frame 18 to cut the stator coil 5, thereby generating an induced electromotive force in the stator coil 5. Figure 5 Permanent magnet 14 has north poles on either side and an south pole in the middle. Excitation current flows through the excitation coil 12 of the electromagnetic spring device in the direction shown in the figure. When permanent magnet 14 deviates from its equilibrium position and moves to one side, the magnetic field it generates, as indicated by the direction of the excitation current in the figure, causes the permanent magnet 14 to experience repulsive forces from the electromagnetic springs on both sides. Because the upper and lower electromagnetic springs have identical structures and are at the same distance from the equilibrium position, the repulsive force generated by the excitation coil 2 of the electromagnetic spring closer to the permanent magnet 14 is necessarily greater than the repulsive force generated by the excitation coil 2 of the electromagnetic spring farther away. As the displacement from the equilibrium position increases, the repulsive force exerted on the permanent magnet 14 by the electromagnetic springs also increases. As the permanent magnet 14 moves within the stator mount 18, it experiences an electromagnetic force opposite to the direction of displacement, acting similarly to a spring. Consequently, the piston 3 is also subjected to a spring-like elastic force, causing it to perform reciprocating sinusoidal motion in the radial direction of the cylinder 11.

[0032] When the magnitude of the current in the excitation coil 12 of the electromagnetic spring is changed, the electromagnetic elastic force exerted on the permanent magnet 14 during the reciprocating motion will also change linearly with the magnitude of the excitation current, and the electromagnetic elastic force exerted on the moving piston 3 will also change linearly with the magnitude of the excitation current. That is, the stiffness of the electromagnetic spring changes linearly with the magnitude of the excitation current.

[0033] The present invention replaces the leaf spring of the moving piston 3 with an electromagnetic spring device 1 with variable stiffness, which can prevent the stiffness from deteriorating during long-term operation, has higher precision, and avoids the problem of leaf spring breakage caused by mechanical fatigue. The stiffness of the electromagnetic spring device 1 with variable stiffness is less affected by factors such as ambient temperature, has stable elastic force, and has strong dynamic response capability, and can be applied to various scenarios where Stirling generators operate. The electromagnetic spring device 1 with variable stiffness has extremely low manufacturing costs, requires almost no maintenance, and has a simple structure and a small size. Compared with the leaf spring structure, it can significantly reduce the structural complexity of the Stirling power generation system. At the same time, since it does not need to be connected to moving parts such as connecting rods and moving pistons, the difficulty of assembly is significantly reduced. By adjusting the magnitude of the excitation current of the electromagnetic spring device to change the stiffness of the electromagnetic spring device, the Stirling power generation system can be adapted to different workloads and working conditions.

[0034] Those skilled in the art may make various modifications and variations to the present invention. If these modifications and variations are within the scope of the claims of the present invention and their equivalents, then these modifications and variations are also within the scope of protection of the present invention.

[0035] The contents not described in detail in the specification are prior art known to those skilled in the art.

Claims

1. A Stirling generator with a variable stiffness electromagnetic spring device, characterized in that: The cam is provided with a plurality of air-conditioning elements, and the plurality of air-conditioning elements are connected to each other through the air-conditioning element, and the plurality of air-conditioning elements are connected to each other through the air-conditioning element. The ring is an annular structure, and the magnetic isolation ring is arranged on one side of the electromagnetic spring wire clamp. The structure of the second electromagnetic spring is the same as that of the first electromagnetic spring. The first electromagnetic spring is connected to the upper end of the linear motor through the magnetic isolation ring, and the second electromagnetic spring is connected to the lower end of the linear motor through the magnetic isolation ring; the linear motor includes a permanent magnet, a stator coil, a magnet support frame, a stator yoke, a stator fixing frame and a moving piston fixing frame. The permanent magnet is composed of multiple groups of permanent magnet pieces with opposite polarities wrapped around the outer wall of the magnet support frame. The permanent magnet is arranged on the outer surface of the moving piston fixing frame. The moving piston is connected to the permanent magnet through the moving piston fixing frame to drive the permanent magnet to move; the lower part of the moving piston fixing frame is connected to the magnet support frame, and the upper part of the power piston fixing frame is connected to the moving piston; the stator yoke is composed of C-shaped silicon steel sheets stacked symmetrically above and below, and the stator coil is wound inside the stator yoke; the inside of the stator fixing frame is connected to the stator yoke; the first electromagnetic spring is connected to the upper surface of the stator fixing frame through the magnetic isolation ring, and the second electromagnetic spring is connected to the lower surface of the stator fixing frame through the magnetic isolation ring.

2. The Stirling generator with a variable stiffness electromagnetic spring device according to claim 1, wherein: The excitation coil is an enameled coil with 200 turns.

3. The Stirling generator with a variable stiffness electromagnetic spring device according to claim 1, wherein: The stator coils are two groups of 400-turn enameled coils.

4. The Stirling generator with a variable stiffness electromagnetic spring device according to claim 1, wherein: The stator fixing frame is formed by connecting two upper and lower circular stainless steels with multiple stainless steel columns, and the overall structure is cage-shaped, and multiple threaded holes are opened on the upper and lower parts of the circular rings.

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