Liquid metal magnetohydrodynamic power generation system driven by free piston internal combustion engine

Abstract

The invention relates to the field of power generation, and provides a free piston internal combustion engine driven liquid metal magnetohydrodynamic power generation system which comprises an air cylinder, a liquid piston, a fuel feeding pipeline, a spark plug, an exhaust pipeline, an air inlet valve, an exhaust valve and a permanent magnet. The liquid piston is filled with liquid metal, the air inlet valve is used for controlling opening and closing of the fuel feeding pipeline, the exhaust valve is used for controlling opening and closing of the exhaust pipeline, and the return cylinder is filled with gas to form a gas spring. Therefore, the liquid metal magnetohydrodynamic generator is formed to serve as a power generation device to replace a linear generator in a free piston internal combustion engine generator, a power generation system with a thermoelectric conversion core free of mechanical moving parts is achieved, friction loss is effectively reduced, power generation efficiency is improved, restoring force is provided by a gas spring, and system reliability is high. And meanwhile, good frequency matching is realized by controlling the opening and closing time of the air inlet and exhaust valve, so that the liquid metal magnetohydrodynamic generator works under the optimal power generation performance.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation, and particularly to a liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine. Background Art

[0002] A linear free piston power generation system is formed by directly coupling a linear generator and a free piston engine. The linear reciprocating motion of the piston drives the generator rotor to cut the magnetic induction line to generate electric energy. Compared with the traditional internal combustion engine power generation system, the linear motor type free piston internal combustion generator has a simple structure, a shortened energy transfer path, and a high energy conversion efficiency, and is regarded as a new energy conversion system to replace the traditional internal combustion engine in the future.

[0003] A magnetohydrodynamic generator is an electromechanical conversion device that converts the mechanical energy of a fluid into electrical energy by using the interaction between a conductive fluid and a magnetic field. A liquid metal magnetohydrodynamic generator refers to a magnetohydrodynamic generator whose working medium is liquid metal. Since there are no mechanical moving parts in the energy conversion process of this power generation technology and the energy conversion efficiency is relatively high, it has a wide range of applications in wave energy power generation, space energy conversion and other fields. According to different current extraction methods, liquid metal magnetohydrodynamic generators can be divided into two types: conductive and inductive. In an inductive liquid metal magnetohydrodynamic generator, the current is extracted by an induction coil wound outside the working medium channel, and the magnitude of the output current and voltage can be controlled by the number of turns of the coil. However, the structure is complex and it is only applicable to AC power generation. In a conductive liquid metal magnetohydrodynamic generator, the current is extracted by electrodes on both sides of the working medium channel. The output current is large and the voltage is small, and generally an additional transformer is required to meet the application requirements. However, the conductive structure is simple and can be used for both AC and DC power generation.

[0004] Patent CN115355086A discloses a single-cylinder free piston internal combustion power generation system, which uses a piston to divide the cylinder into a separated high-pressure gas source cylinder and a combustion cylinder. High-temperature and high-pressure gas generated by combustion in the combustion cylinder is used to push the piston to do work, and the restoring force of the piston is provided by the cooperation of a spring restoring mechanism and a high-pressure gas source mechanism. The linear motor rotor is fixedly installed on the connecting rod, and the other end of the connecting rod is fixedly connected to the piston. The reciprocating motion of the piston drives the linear motor rotor to cut the magnetic induction line to generate electric energy. However, due to the use of a piston connecting rod mechanism, there are mechanical moving parts, and there is friction loss between the piston and the cylinder. Moreover, the restoring force of the piston relies on the spring restoring mechanism, and the high-frequency reciprocating motion is likely to cause fatigue fracture of the spring, resulting in low system reliability.

[0005] Patent CN116816625A proposes a liquid metal magnetohydrodynamic power generation system driven by a two-stage loop traveling wave thermoacoustic engine. This system uses two thermoacoustic conversion units connected end to end to form a traveling wave loop, and two liquid metal magnetohydrodynamic generators are arranged in the traveling wave loop. However, due to the limitations of its own structure, the operating frequency of the thermoacoustic system is usually above 20 Hz. While the electromechanical conversion efficiency of the liquid metal magnetohydrodynamic generator is higher at low frequencies, and its operating frequency is usually less than 10 Hz. Therefore, there are technical difficulties in their matching, resulting in poor operating performance of the existing thermoacoustic-driven liquid metal magnetohydrodynamic generators. Summary of the Invention

[0006] The purpose of the present invention is to provide a liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine, so as to solve the problems in the prior art that the traditional linear motor type free piston internal combustion generator using a spring return mechanism has low reliability, there are mechanical moving parts, serious friction and wear, low efficiency, and the difficulty of acoustic-electric matching of the thermoacoustic-driven liquid metal magnetohydrodynamic generator is large and the operating performance is not good.

[0007] In order to achieve the above purpose, the present invention provides a liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine, including:

[0008] A cylinder;

[0009] A liquid piston, reciprocating in the cylinder. The liquid piston is filled with liquid metal magnetohydrodynamic fluid, and the liquid piston divides the interior of the cylinder into an independent combustion cylinder and a return cylinder. The return cylinder is filled with gas to form a gas spring.

[0010] A fuel feed pipeline, a spark plug and an exhaust pipeline, arranged on the combustion cylinder;

[0011] An intake valve, arranged on the fuel feed pipeline, and the intake valve is used to control the opening and closing of the fuel feed pipeline;

[0012] An exhaust valve, arranged on the exhaust pipeline, and the exhaust valve is used to control the opening and closing of the exhaust pipeline;

[0013] A pair of oppositely arranged permanent magnets, respectively arranged on opposite sides of the liquid piston to form a magnetic field around the liquid metal magnetohydrodynamic fluid. The liquid piston reciprocates in the magnetic field to cut the magnetic induction lines to generate an induced current.

[0014] According to the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention, the cylinder has a linear structure, and the cylinder includes:

[0015] A pair of elastic membranes are arranged in the cylinder at intervals. A liquid metal channel for accommodating the liquid metal magnetohydrodynamic fluid is formed between the pair of elastic membranes. The pair of elastic membranes and the liquid metal magnetohydrodynamic fluid constitute the liquid piston, so as to divide the interior of the cylinder into the combustion cylinder and the return cylinder.

[0016] For the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention, the cylinder has a U-shaped structure, and the cylinder includes:

[0017] Two vertical parts arranged at intervals;

[0018] A horizontal part is connected between the two vertical parts;

[0019] Two floats are respectively arranged in the two vertical parts. A liquid metal channel for accommodating the liquid metal magnetohydrodynamic fluid is formed between the two floats. The two floats and the liquid metal magnetohydrodynamic fluid constitute the liquid piston, so as to divide the interior of the cylinder into the combustion cylinder and the return cylinder. A pair of permanent magnets are respectively arranged on the upper side and the lower side of the horizontal part.

[0020] For the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention, the number of the elastic membranes is two pairs. The two pairs of elastic membranes are arranged in the cylinder at intervals to divide the interior of the cylinder into three partitions. One of the partitions is set as the combustion cylinder, and the remaining two partitions are set as the return cylinders. The two return cylinders are located on both sides of the combustion cylinder, and the permanent magnet is arranged in one-to-one correspondence with the liquid metal channel.

[0021] For the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention, the cylinder has a double-U-shaped structure, the number of the vertical parts is three, and the floats are arranged in one-to-one correspondence with the vertical parts to divide the interior of the cylinder into three partitions. One of the partitions is set as the combustion cylinder, and the remaining two partitions are set as the return cylinders. The two return cylinders are located on both sides of the combustion cylinder, and the permanent magnet is arranged in one-to-one correspondence with the horizontal part.

[0022] For the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention, the number of the cylinders is two, and the two cylinders are arranged oppositely between a pair of permanent magnets.

[0023] For the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention, it further includes:

[0024] A pressure regulating valve is arranged on the return cylinder, and the pressure regulating valve is used to adjust the gas pressure in the return cylinder.

[0025] According to the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention, the fuel feed pipeline includes:

[0026] A fuel branch for supplying fuel into the combustion cylinder;

[0027] A gas branch for supplying combustion-supporting gas into the combustion cylinder, and both the fuel branch and the gas branch are connected to the intake valve.

[0028] According to the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention, the fuel is one of gasoline, methanol, propane, and hydrogen.

[0029] According to the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention, the liquid metal magnetohydrodynamic fluid is one of liquid sodium, liquid sodium-potassium alloy, mercury, and gallium-indium-tin alloy.

[0030] The liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention includes: a cylinder; a liquid piston that reciprocates inside the cylinder. The liquid piston is filled with a liquid metal magnetohydrodynamic fluid, and the liquid piston divides the interior of the cylinder into an independent combustion cylinder and a return cylinder. The return cylinder is filled with gas to form a gas spring; a fuel feed pipeline, a spark plug, and an exhaust pipeline are arranged on the combustion cylinder; an intake valve is arranged on the fuel feed pipeline, and the intake valve is used to control the opening and closing of the fuel feed pipeline; an exhaust valve is arranged on the exhaust pipeline, and the exhaust valve is used to control the opening and closing of the exhaust pipeline; a pair of oppositely arranged permanent magnets are respectively arranged on opposite sides of the liquid piston to form a magnetic field around the liquid metal magnetohydrodynamic fluid. The liquid piston reciprocates in the magnetic field to cut the magnetic induction lines to generate an induced current.

[0031] With such an arrangement, a liquid piston is formed by using a liquid metal, and a liquid metal magnetohydrodynamic generator is formed as a power generation device to replace the linear generator in a traditional free piston internal combustion generator, realizing a power generation system without mechanical moving parts in the core of thermoelectric conversion. It can effectively reduce frictional losses, improve power generation efficiency, and provide a restoring force through the gas spring, making the system more reliable. At the same time, by controlling the opening and closing times of the intake and exhaust valves, good frequency matching can be achieved, enabling the liquid metal magnetohydrodynamic generator to operate in the optimal power generation performance state, overcoming the problem of difficult matching existing in traditional thermoacoustic-driven liquid metal magnetohydrodynamic power generation systems. Description of the Drawings

[0032] To more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 It is one of the schematic structural diagrams of the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention;

[0034] Figure 2 It is the second schematic structural diagram of the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention;

[0035] Figure 3 It is the third schematic structural diagram of the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention;

[0036] Figure 4 It is the fourth schematic structural diagram of the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention;

[0037] Figure 5 It is the fifth schematic structural diagram of the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine provided by the present invention;

[0038] Reference numerals:

[0039] 1: Cylinder; 11: Combustion cylinder; 12: Return cylinder; 13: Elastic membrane; 14: Vertical part; 15: Horizontal part; 16: Float; 2: Liquid metal magnetohydrodynamic; 3: Gas branch; 4: Fuel branch; 5: Exhaust pipe; 6: Spark plug; 7: Intake valve; 8: Exhaust valve; 9: Permanent magnet; 10: Liquid metal channel; 20: Pressure regulating valve. Detailed implementation manners

[0040] To make the objectives, technical solutions and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the present invention in conjunction with the drawings in the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0041] The following will describe in conjunction with Figures 1 to 5 the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine of the present invention.

[0042] As shown in Figures 1 to 5As shown in the figure, an embodiment of the present invention provides a liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine, which includes a cylinder 1, a liquid piston, a fuel feed pipeline, a spark plug 6, an exhaust pipeline 5, an intake valve 7, an exhaust valve 8, and a pair of permanent magnets 9. Specifically, as Figure 1 shown, the liquid piston reciprocates within the cylinder 1. The liquid piston is filled with liquid metal magnetohydrodynamic fluid 2, and the liquid piston divides the interior of the cylinder 1 into an independent combustion chamber 11 and a return chamber 12. The fuel feed pipeline, the spark plug 6, and the exhaust pipeline 5 are provided on the cylinder wall of the combustion chamber 11, where the fuel feed pipeline is used to transport the combustion working medium, the spark plug 6 is used to ignite the combustion working medium, and the exhaust pipeline 5 is used to discharge the combustion exhaust gas. The intake valve 7 is provided on the fuel feed pipeline, and the intake valve 7 is used to control the opening and closing of the fuel feed pipeline. The exhaust valve 8 is provided on the exhaust pipeline 5, and the exhaust valve 8 is used to control the opening and closing of the exhaust pipeline 5. Thus, by controlling the opening and closing times of the two valves, the purpose of controlling the movement frequency of the liquid metal magnetohydrodynamic fluid 2 is achieved, and further the output frequency of the generator can be regulated.

[0043] The return chamber 12 is filled with gas to form a gas spring as a return mechanism. Compression energy storage is achieved by compressing the gas in the return chamber 12, and release is achieved by the natural expansion of the gas, thereby providing a return force for the movement of the liquid metal magnetohydrodynamic fluid 2. Generally, there is no need to supply gas frequently to the return chamber 12. A pair of permanent magnets 9 are arranged oppositely and are respectively arranged on the opposite sides of the liquid piston. Specifically, a pair of permanent magnets 9 are respectively placed on the upper and lower sides of the liquid metal magnetohydrodynamic fluid 2 to form a relatively uniform vertically distributed magnetic field around the liquid metal magnetohydrodynamic fluid 2. The liquid piston reciprocates in the magnetic field to cut the magnetic induction lines to generate an induced current. Generally, electrode plates and connection terminals are provided on the front and rear sides of the liquid metal magnetohydrodynamic fluid 2 to output the induced current generated by the liquid metal magnetohydrodynamic fluid 2 cutting the magnetic induction lines to an external transformer, which is regulated by the external transformer and then output to an external circuit. It should be noted that, taking the placement position of the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine as shown in Figure 1 the figure, the up and down directions in the figure are the up and down orientations referred to, the left and right directions in the figure are the left and right orientations referred to, and the direction perpendicular to the paper surface in the figure is the front and rear direction referred to.

[0044] With such a setting, a liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine with a gas spring reset mechanism is formed. It uses liquid metal to form a liquid piston, and a liquid metal magnetohydrodynamic generator is used as a power generation device to replace the linear generator in the traditional free piston internal combustion generator, realizing a power generation system without mechanical moving parts in the core of thermoelectric conversion. This can effectively reduce frictional losses, improve power generation efficiency, and the system has higher reliability by providing a restoring force through the gas spring. At the same time, by controlling the opening and closing time of the intake and exhaust valves, good frequency matching can be achieved, enabling the liquid metal magnetohydrodynamic generator to operate under the optimal power generation performance state, overcoming the problem of difficult matching in the traditional thermoacoustic-driven liquid metal magnetohydrodynamic power generation system.

[0045] In a specific embodiment of the present invention, the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine includes a pressure regulating valve 20. The pressure regulating valve 20 is arranged on the cylinder wall of the restoring cylinder 12, and the pressure regulating valve 20 is used to regulate the gas pressure in the restoring cylinder 12. During regulation, the pressure can be regulated by connecting an external compressed air source to the pressure regulating valve 20. After the regulation is completed, during the working process, the regulating valve 20 is in a closed state. With such a setting, the gas pressure in the restoring cylinder 12 can be changed through the pressure regulating valve 20, thereby changing the stiffness of the gas spring, and further realizing the regulation of the restoring force of the liquid metal piston to meet different design requirements.

[0046] In a specific embodiment of the present invention, the fuel feed pipeline includes a fuel branch 4 and a gas branch 3. The fuel branch 4 is used to supply fuel to the combustion cylinder 11, and the gas branch 3 is used to supply combustion-supporting gas to the combustion cylinder 11. Specifically, air can be selected. Both the fuel branch 4 and the gas branch 3 are connected to the intake valve 7. With such a setting, a certain amount of fuel and gas can be respectively input according to the requirements of the engine, and after being mixed into a combustible mixture, it enters the combustion cylinder 11 through the intake valve 7 to burn and do work.

[0047] As an alternative embodiment of the present invention, the fuel is one of gasoline, methanol, propane, and hydrogen. In actual applications, a suitable gaseous fuel or liquid fuel can be selected according to actual usage requirements for combustion and work.

[0048] In an alternative embodiment of the present invention, the liquid metal magnetohydrodynamic fluid 2 is one of liquid sodium, liquid sodium-potassium alloy, mercury, and gallium-indium-tin alloy. Of course, in other embodiments, the liquid metal magnetohydrodynamic fluid 2 and the fuel are not limited to the types mentioned above, and specific selections can be made according to actual design requirements to meet actual usage conditions.

[0049] In the first embodiment of the present invention, as Figure 1As shown in the figure, the cylinder 1 has a linear structure. Specifically, the cylinder 1 includes a pair of elastic membranes 13, and the pair of elastic membranes 13 are spaced apart and arranged inside the cylinder 1. A liquid metal channel 10 for accommodating the liquid metal magnetofluid 2 is formed between the pair of elastic membranes 13. The pair of elastic membranes 13 and the liquid metal magnetofluid 2 together constitute a liquid piston, dividing the interior of the cylinder 1 into a combustion cylinder 11 and a recovery cylinder 12. A pair of permanent magnets 9 are respectively placed on the upper and lower sides of the liquid metal channel 10, forming a relatively uniform vertically distributed magnetic field in the liquid metal channel 10. With such a setting, a free piston power generation system is formed with the liquid metal magnetofluid 2 as the liquid piston and the gas spring as the recovery mechanism, including an engine cylinder, i.e., the combustion cylinder 11, a gas spring cylinder, i.e., the recovery cylinder 12, and a liquid metal magnetofluid generator. The engine cylinder and the gas spring cylinder are respectively connected to the liquid metal magnetofluid generator, and the connection part separates the cylinder from the liquid metal piston through the elastic membrane 13 to ensure the stability of the liquid level.

[0050] This power generation system uses a liquid metal magnetofluid generator to replace the linear generator in the traditional linear motor type free piston internal combustion generator, and can constitute a power generation device without mechanical moving parts in the core of thermoelectric conversion. This power generation device combines the characteristics of a free piston engine and a liquid metal magnetofluid generator, has a simple structure, a long service life, a short energy transfer path, and a high energy conversion rate. Therefore, it is expected to become a new generation of efficient, highly reliable and relatively environmentally friendly new power generation device.

[0051] During operation, as Figure 1 shown in the figure, the intake valve 7 opens, and the air in the gas branch 3 and the fuel in the fuel branch 4 enter the combustion cylinder 11 through the intake valve 7. Under the action of the spark plug 6, it is ignited, the gas expands, compressing the left-end elastic membrane 13 to deform to the right, and the thrust generated by the left-end elastic membrane 13 pushes the liquid metal magnetofluid 2 to flow to the right. The liquid metal magnetofluid 2 transfers the force to the right-end elastic membrane 13, and the right-end elastic membrane 13 deforms to the right under the force, and at this time the air in the recovery cylinder 12 is compressed to complete the gas spring energy storage.

[0052] When the intake valve 7 in the combustion cylinder 11 closes and the gas expansion is completed, the exhaust valve 8 opens. At this time, the gas pressure in the recovery cylinder 12 is greater than the pressure in the combustion cylinder 11, and the gas spring releases energy. The gas in the recovery cylinder 12 expands, pushing the right-end elastic membrane 13 to deform to the left, and the thrust generated by the right-end elastic membrane 22 pushes the liquid metal magnetofluid 2 to flow to the left. The liquid metal magnetofluid 2 transfers the force to the left-end elastic membrane 13, and the left-end elastic membrane 13 deforms to the left under the force, and at this time the exhaust gas generated after combustion in the combustion cylinder 11 is discharged through the exhaust valve 8. Thus, a complete working process is completed.

[0053] It should be noted that as Figure 1As for the placement position of the liquid metal magnetohydrodynamic power generation system driven by the free piston internal combustion engine shown in the figure, the up and down directions in the figure refer to the up and down positions, and the left and right directions in the figure refer to the left and right positions.

[0054] During this operation, the engine cylinder completes the combustion and expansion process, while the gas spring cylinder provides the restoring force. The two cylinders work together to cause the liquid metal magnetic fluid 2 to complete a reciprocating motion. During this reciprocating motion, the liquid metal magnetic fluid 2 cuts through the magnetic flux lines generated by the permanent magnets 9 within the liquid metal channel 10. The resulting current is output to an external transformer, which regulates it and then outputs it to the external circuit.

[0055] The power generation device has no mechanical moving parts in its working section, resulting in minimal friction and wear. Furthermore, the device can control the frequency of the liquid metal magnetic fluid 2 by controlling the opening and closing timing of the gas valve, thereby regulating the output frequency of the generator. By combining combustion work within the engine cylinder with the restoring force provided by the gas spring cylinder, the system achieves high reliability and achieves continuous and stable conversion of thermal energy into electrical energy.

[0056] In a second embodiment of the present invention, Figure 2 As shown, the difference from the first embodiment is that the cylinder 1 has a U-shaped structure. Specifically, the cylinder 1 includes two vertical portions 14 spaced apart and a horizontal portion 15 connected between the two vertical portions 14. Two floats 16 are respectively disposed in the two vertical portions 14, forming a liquid metal channel 10 for accommodating the liquid metal magnetic fluid 2 between the two floats 16. The two floats 16 and the liquid metal magnetic fluid 2 together form a liquid piston, dividing the interior of the cylinder 1 into a combustion cylinder 11 and a return cylinder 12. A pair of permanent magnets 9 are respectively disposed on the upper and lower sides of the horizontal portion 15, thereby forming a relatively uniform vertically distributed magnetic field within the liquid metal channel 10. This configuration forms a U-shaped liquid metal magnetic fluid free piston power generation system, which is conducive to stabilizing the liquid metal level and better completing the exhaust process. The power generation system includes an engine cylinder (i.e., the combustion cylinder 11) and a gas spring cylinder (i.e., the return cylinder 12) disposed at both ends of the U-shaped body, and a liquid metal magnetic fluid generator. The engine cylinder and the gas spring cylinder are respectively connected to the liquid metal magnetohydrodynamic generator, and the connection is separated from the liquid metal piston by a float 16 to ensure the stability of the liquid level.

[0057] When working, Figure 2As shown, the intake valve 7 is opened, and the air in the gas branch 3 and the fuel in the fuel branch 4 enter the combustion cylinder 11 through the intake valve 7. Ignited by the spark plug 6, the gas expands, pushing the left-end float 16 downward, and the liquid level in the combustion cylinder 11 drops. The liquid metal magnetohydrodynamic fluid 2 transmits the force to the right-end float 16, the liquid level in the return cylinder 12 rises, the right-end float 16 moves upward, and the air in the return cylinder 12 is compressed to complete the energy storage of the gas spring.

[0058] When the intake valve 7 in the combustion cylinder 11 is closed and the gas expansion is completed, the exhaust valve 8 is opened. At this time, the sum of the gas pressure in the return cylinder 12 and the liquid column pressure of the liquid metal is greater than the pressure in the combustion cylinder 11, and the gas spring releases. The gas in the return cylinder 12 expands, pushing the right-end float 22 downward. The thrust generated by the right-end float 22 and the self-gravity of the liquid metal magnetohydrodynamic fluid 2 cause the liquid metal magnetohydrodynamic fluid 2 to flow. The liquid metal magnetohydrodynamic fluid 2 transmits the force to the left-end float 14, the left-end float 14 moves upward under the force, the liquid level in the combustion cylinder 11 rises, and the exhaust gas generated after combustion in the combustion cylinder 11 is discharged through the exhaust valve 8. Thus, a complete working process is completed.

[0059] It should be noted that Figure 2 in terms of the placement position of the liquid metal magnetohydrodynamic power generation system driven by the free piston internal combustion engine as shown, the up and down directions in the figure are the indicated up and down orientations, and the left and right directions in the figure are the indicated left and right orientations.

[0060] In the above working process, the engine cylinder completes the combustion expansion process, and the gas spring cylinder and the gravity of the liquid metal column provide the restoring force. The two cylinders cooperate with each other to make the liquid metal magnetohydrodynamic fluid 2 complete a reciprocating motion. During the reciprocating motion of the liquid metal magnetohydrodynamic fluid 2, it cuts the magnetic induction lines generated by the permanent magnet 9 in the liquid metal channel 10, and the generated current is output to the external transformer and then output to the external circuit after being adjusted by the external transformer. Since the float 16 is adopted in this device, the liquid metal liquid level is more stable, and the reliability of the system is improved.

[0061] In the third embodiment of the present invention, as Figure 3As shown, the difference from the first embodiment is that the number of elastic membranes 13 is two pairs, and the two pairs of elastic membranes 13 are arranged at intervals within the cylinder 1, thereby forming two liquid pistons to divide the interior of the cylinder 1 into three partitions. Specifically, one of the partitions is set as the combustion cylinder 11, and the remaining two partitions are set as the return cylinders 12. The two return cylinders 12 are located on the left and right sides of the combustion cylinder 11. Moreover, the permanent magnets 9 are arranged in one-to-one correspondence with the liquid metal channels 10, so as to form a relatively uniform vertically distributed magnetic field in the liquid metal channels 10 on both sides respectively. With such an arrangement, a liquid metal magnetohydrodynamic free piston power generation system is formed, where the engine cylinder, i.e., the combustion cylinder 11, is in the middle, and the gas spring cylinders, i.e., the return cylinders 12, are oppositely distributed on both sides. By burning gas and expanding to do work in the engine cylinder in the middle, the gas springs on both sides provide a restoring force, causing the liquid metal magnetohydrodynamic fluid 2 in the liquid metal channels 10 on both sides to flow reciprocally. In this system, one combustion and work done can make the magnetohydrodynamic generators on both the left and right sides complete one reciprocating motion, which is conducive to making full use of the energy released by fuel combustion, giving full play to the engine performance, and improving the overall efficiency of the system.

[0062] During operation, as Figure 3 shown, the intake valve 7 opens, and the air in the gas branch 3 and the fuel in the fuel branch 4 enter the combustion cylinder 11 through the intake valve 7 and are ignited under the action of the spark plug 6. The gas expands and simultaneously pushes the two pairs of elastic membranes 14 on both sides to move. Its specific working principle is similar to that described in the first embodiment. Finally, the air in the return cylinders 12 on both sides is compressed to complete the energy storage of the gas springs on both sides.

[0063] After that, similar to the first embodiment, when the intake valve 7 in the combustion cylinder 11 closes and the gas expansion is completed, the exhaust valve 8 opens. The gas springs on both sides release energy and respectively push the liquid metal magnetohydrodynamic fluid 2 in the liquid metal channels 10 on both sides to move, causing the exhaust gas generated after combustion in the combustion cylinder 11 to be discharged through the exhaust valve 8. Thus, the liquid metal magnetohydrodynamic fluid 2 in the liquid metal channels 10 on both sides realizes reciprocating motions in opposite directions to complete a complete working process.

[0064] It should be noted that, regarding the placement position of the liquid metal magnetohydrodynamic power generation system driven by the free piston internal combustion engine as shown in Figure 3 the figure, the up and down directions in the figure are the indicated up and down orientations, and the left and right directions in the figure are the indicated left and right orientations.

[0065] Since the engine part in this device is located in the middle of the system, one combustion can expand and do work simultaneously to both sides, enabling the magnetohydrodynamic generators on both the left and right sides to complete one reciprocating motion, making full use of the energy released by fuel combustion to improve the power generation efficiency of the system.

[0066] In the fourth embodiment of the present invention, as Figure 4As shown, the difference from the second embodiment is that the cylinder 1 has a double U-shaped structure. Specifically, the number of vertical portions 14 is three, and correspondingly, the number of horizontal portions 15 is two. The permanent magnets 9 are arranged in one-to-one correspondence with the horizontal portions 15, so that a relatively uniform vertically distributed magnetic field can be formed in the two liquid metal channels 10 on both sides. And the floats 16 are arranged in one-to-one correspondence with the vertical portions 14, that is, the number of floats 16 is three, and a liquid piston is formed between two adjacent floats 16, thus constituting two liquid pistons to divide the interior of the cylinder 1 into three partitions. Specifically, one of the partitions is set as the combustion cylinder 11, and the remaining two partitions are set as the return cylinders 12. The two return cylinders 12 are located on the left and right sides of the combustion cylinder 11. With such an arrangement, a liquid metal magnetohydrodynamic free piston power generation system with a double U-shaped body where the engine cylinder, i.e., the combustion cylinder 11, is in the middle is formed, which is beneficial to stabilizing the liquid metal liquid level, better completing the exhaust process, and giving full play to the performance of the engine.

[0067] During operation, as Figure 4 shown, the intake valve 7 is opened, and the air in the gas branch 3 and the fuel in the fuel branch 4 enter the combustion cylinder 11 through the intake valve 7. Under the action of the spark plug 6, it is ignited, the gas expands, pushes the middle float 16 downward, and the thrust generated by the middle float 14 simultaneously pushes the liquid metal magnetohydrodynamic fluid 2 in the two liquid metal channels 10 to flow, and the liquid level in the combustion cylinder 11 drops. The liquid metal magnetohydrodynamic fluid 2 transmits the force to the floats 16 at both ends, causing the liquid levels in the two return cylinders 12 to rise and the floats 16 to move upward. Finally, the air in the two return cylinders 12 is compressed to complete the gas spring energy storage on both sides.

[0068] After that, similar to the second embodiment, when the intake valve 7 in the combustion cylinder 11 is closed and the gas expansion is completed, the exhaust valve 8 is opened. At this time, the sum of the gas pressure in the two return cylinders 12 and the gravity of the liquid metal liquid column is greater than the pressure in the combustion cylinder 11, and the gas spring releases. The gas in the two return cylinders 12 expands, pushes the floats 16 at both ends downward, and the thrust generated by the floats 16 at both ends pushes the liquid metal magnetohydrodynamic fluid 2 to flow. The liquid metal magnetohydrodynamic fluid 2 transmits the force to the middle float 14, and the middle float 14 moves upward under the force, and the liquid level in the combustion cylinder 11 rises, and the exhaust gas generated after combustion in the combustion cylinder 11 is discharged through the exhaust valve 8. Thus, a complete working process is completed.

[0069] It should be noted that for the placement position of the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine as Figure 4 shown, the up and down directions in the figure are the up and down orientations referred to, and the left and right directions in the figure are the left and right orientations referred to.

[0070] Since a float 16 is adopted in the device to facilitate the stabilization of the liquid level, and the engine part is located in the middle of the system, during one power generation process, the liquid metal generators on both sides respectively complete one reciprocating motion and generate electricity once, which is conducive to the full utilization of the fuel combustion energy, improving the stability and power generation efficiency of the system.

[0071] In the fifth embodiment of the present invention, as Figure 5 shown, the difference from the first embodiment is that the number of cylinders 1 is two, and the two cylinders 1 are arranged oppositely between a pair of permanent magnets 9. With such an arrangement, an opposed liquid metal magnetohydrodynamic free piston power generation system is formed. Through staggered combustion and power generation, the liquid metal magnetohydrodynamic 2 in the liquid metal channels 10 of the two cylinders 1 reciprocates in opposite directions, thereby generating opposite current directions, which is conducive to canceling the induced magnetic field excited by the current and suppressing the inductance inside the liquid metal magnetohydrodynamic generator, so that the power generation efficiency of the liquid metal magnetohydrodynamic generator is improved. At the same time, the use of the staggered power generation method is beneficial to reducing the system vibration and ensuring the stable operation of the system.

[0072] During operation, as Figure 5 shown, for the cylinder 1 located above: the left end intake valve 7 is opened, and the air in the gas branch 3 and the fuel in the fuel branch 4 enter the left end combustion cylinder 11 through the intake valve 7 and are ignited under the action of the spark plug 6. The gas expands, pushing the left end elastic membrane 13 to deform to the right. The thrust generated by the left end elastic membrane 13 pushes the liquid metal magnetohydrodynamic 2 to flow to the right. The liquid metal magnetohydrodynamic 2 transmits the force to the right end elastic membrane 13, and the right end elastic membrane 13 deforms to the right under the force. At this time, the air in the right end recovery cylinder 12 is compressed, completing the gas spring energy storage.

[0073] At the same time, for the cylinder 1 located below: the same combustion process occurs. The difference from the upper cylinder 1 is that the combustion cylinder 11 is located at the right end and the recovery cylinder 12 is located at the left end. The moving direction of the liquid metal magnetohydrodynamic 2 is opposite, that is, it moves to the left, and finally the air in the left end recovery cylinder 12 is compressed, completing the gas spring energy storage.

[0074] After that, similar to the first embodiment, for the cylinder 1 located above: when the intake valve 7 in the left end combustion cylinder 11 is closed and the gas expansion is completed, the exhaust valve 8 is opened. The right end gas spring releases, pushing the liquid metal magnetohydrodynamic 2 to move to the left, so that the left end combustion cylinder 11 completes the exhaust process.

[0075] At the same time, for the cylinder 1 located below: the same energy release process occurs. The difference from the upper cylinder 1 is that the moving direction of the liquid metal magnetohydrodynamic 2 is opposite, that is, it moves to the right, and finally the right end combustion cylinder 11 completes the exhaust process.

[0076] As a result, the liquid metal magnetohydrodynamics 2 in the upper and lower cylinders 1 performs reciprocating motions in opposite directions, completing a complete working process.

[0077] It should be noted that, taking the placement position of the liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine as shown in Figure 5 the figure, the up and down directions in the figure are the so-called up and down orientations, and the left and right directions in the figure are the so-called left and right orientations.

[0078] During the above working process, the reciprocating motions of the upper and lower liquid metal magnetohydrodynamics 2 are in opposite directions, generating opposite induced currents, which are output to the external circuit. Since the current directions are opposite, the induced magnetic fields excited cancel each other out, which can effectively suppress the inductance inside the liquid metal magnetohydrodynamic generator, is beneficial to reducing the phase difference between the load voltage and the load current of the generator, and improving the power generation efficiency. At the same time, since the expansion work processes on both the left and right sides of the whole body are carried out simultaneously, the generated thrusts inhibit each other, reducing the system vibration and being beneficial to the stable operation of the system.

[0079] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A free-piston internal combustion engine-driven liquid metal magnetohydrodynamic power generation system, characterized in that, Comprising: A cylinder (1); A liquid piston, reciprocating within the cylinder (1), filled with liquid metal magnetofluid (2), and the liquid piston divides the interior of the cylinder (1) into an independent combustion chamber (11) and a return chamber (12), wherein the return chamber (12) is filled with gas to form a gas spring; A fuel feed pipeline, a spark plug (6) and an exhaust pipeline (5), arranged on the combustion chamber (ll); An intake valve (7), arranged on the fuel feed pipeline, and the intake valve (7) is used to control the opening and closing of the fuel feed pipeline; An exhaust valve (8), arranged on the exhaust pipeline (5), and the exhaust valve (8) is used to control the opening and closing of the exhaust pipeline (5); A pair of oppositely arranged permanent magnets (9), respectively arranged on opposite sides of the liquid piston, to form a magnetic field around the liquid metal magnetofluid (2), and the liquid piston reciprocates in the magnetic field to cut the magnetic induction lines to generate an induced current.

2. The liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine according to claim 1, wherein The cylinder (1) has a linear structure, and the cylinder (1) comprises: A pair of elastic membranes (13), spaced within the cylinder (1), and a liquid metal channel (10) for accommodating the liquid metal magnetofluid (2) is formed between the pair of elastic membranes (13). The pair of elastic membranes (13) and the liquid metal magnetofluid (2) constitute the liquid piston to divide the interior of the cylinder (1) into the combustion chamber (11) and the return chamber (12).

3. The liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine according to claim 1, wherein The cylinder (1) has a U-shaped structure, and the cylinder (1) comprises: Two spaced vertical portions (14); A horizontal portion (15), communicatively arranged between the two vertical portions (14); Two floats (16), respectively arranged in the two vertical portions (14), and a liquid metal channel (10) for accommodating the liquid metal magnetofluid (2) is formed between the two floats (16). The two floats (16) and the liquid metal magnetofluid (2) constitute the liquid piston to divide the interior of the cylinder (1) into the combustion chamber (11) and the return chamber (12), and the pair of permanent magnets (9) are respectively arranged on the upper side and the lower side of the horizontal portion (15).

4. The free piston internal combustion engine-driven liquid metal magnetohydrodynamic power generation system according to claim 2, wherein The number of the elastic membranes (13) is two pairs, and the two pairs of elastic membranes (13) are spaced within the cylinder (1) to divide the interior of the cylinder (1) into three zones, wherein one of the zones is set as the combustion chamber (11), and the remaining two zones are set as the return chambers (12). The two return chambers (12) are located on both sides of the combustion chamber (11), and the permanent magnet (9) is arranged in one-to-one correspondence with the liquid metal channel (10).

5. The liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine according to claim 3, characterized in that, The cylinder (1) has a double U-shaped structure. The number of the vertical parts (14) is three, and the float (16) is arranged in one-to-one correspondence with the vertical part (14) to divide the interior of the cylinder (1) into three partitions. One of the partitions is set as the combustion cylinder (11), and the remaining two partitions are set as the return cylinders (12). The two return cylinders (12) are located on both sides of the combustion cylinder (11). The permanent magnets (9) are arranged in one-to-one correspondence with the horizontal part (15).

6. The liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine according to claim 2, characterized in that, The number of the cylinders (1) is two, and the two cylinders (1) are arranged oppositely between a pair of permanent magnets (9).

7. The liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine according to claim 1, wherein, It further includes: A pressure regulating valve (20) is arranged on the return cylinder (12), and the pressure regulating valve (20) is used to regulate the gas pressure in the return cylinder (12).

8. The liquid metal magnetohydrodynamic power generation system driven by a free piston internal combustion engine according to claim 1, characterized in that, The fuel feed pipeline includes: A fuel branch (4) for supplying fuel to the combustion cylinder (11); A gas branch (3) for supplying combustion-supporting gas to the combustion cylinder (11). The fuel branch (4) and the gas branch (3) are both connected to the intake valve (7).

9. The free-piston internal combustion engine-driven liquid metal magnetohydrodynamic power generation system according to claim 8, wherein The fuel is one of gasoline, methanol, propane, and hydrogen.

10. The free-piston internal combustion engine-driven liquid metal magnetohydrodynamic power generation system according to claim 1, characterized in that, The liquid metal magnetofluid (2) is one of liquid sodium, liquid sodium-potassium alloy, mercury, and gallium-indium-tin alloy.

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