Rigidity-adjustable magnetic spring applied to point absorption type wave power generation device

Abstract

The invention provides a rigidity-adjustable magnetic spring applied to a point absorption type wave power generation device, the rigidity-adjustable magnetic spring is composed of a shell, an elastic force generating part and a rigidity adjusting part, and the elastic force generating part is composed of a rotor, a stator and stator back iron; the rigidity adjusting part is composed of a stepping motor and two connecting shafts. The stepping motor is used for controlling the angle of magnetic interaction between the rotor and the stator so as to generate different rigidities; the rotor is formed by splicing two cylindrical permanent magnets, one of the two permanent magnets is magnetized along the positive direction of the axial direction, the other one is magnetized along the negative direction of the axial direction, the stator is formed by splicing four cylindrical permanent magnets, two of the four permanent magnets are magnetized along the positive direction of the radial direction, two of the four permanent magnets are magnetized along the negative direction of the radial direction, and the stator permanent magnets are rigidly connected with the stator back iron. According to the spring, the magnetic spring can generate positive rigidity or negative rigidity, and the requirements for long stroke and large thrust of waves can be better met.

Description

Technical Field

[0001] The present invention relates to the technical field of wave power generation, in particular to an adjustable stiffness magnetic spring applied to a point absorption type wave power generation device. Background Art

[0002] Wave power generation is being widely researched as a new renewable energy source. Among the various wave power generation devices, point absorption wave power generation devices are widely studied due to their high stability. In wave power generation devices, springs are often used to prevent the generator from operating out of range or to balance external capacitive impedance. To enable the generator to capture more energy from the waves, the spring stiffness coefficient needs to be dynamically adjusted according to the external wave excitation force. However, current adjustable springs suffer from low thrust and short stroke. Therefore, there is a need to design adjustable magnetic springs with long stroke and high thrust for wave power generation. Summary of the Invention

[0003] The purpose of the present invention is to propose an adjustable stiffness magnetic spring for use in a point absorption wave power generation device. The stiffness is adjusted by rotating a stepper motor to adjust the angle of magnetic pole alignment between the spring mover and the stator, thereby having the advantage of free adjustment between positive and negative stiffness, and can better adapt to the requirements of long wave stroke and high thrust.

[0004] The purpose of the present invention is achieved through the following technical solutions:

[0005] The application relates to an adjustable stiffness magnetic force spring applied to a point absorption type wave power generation device, which comprises a shell, a magnetic force generating mechanism and a stiffness adjusting mechanism, the magnetic force generating mechanism comprises a stator back iron, first and second mover permanent magnets, first, second, third and fourth stator permanent magnets, the stiffness adjusting mechanism comprises first and second connecting shafts and a stepping motor, the stator back iron is located in the shell, the first, second, third and fourth stator permanent magnets are arranged in the cavity of the stator back iron, the first and second mover permanent magnets are arranged outside the first, second, third and fourth stator permanent magnets, the stepping motor is located outside the shell, one end of the first connecting shaft is connected with the stepping motor, the other end of the first connecting shaft extends to the cavity of the stator back iron through one side wall of the shell and is rigidly connected with the first and second mover permanent magnets, the second connecting shaft is located on the side opposite to the first connecting shaft, one end of the second connecting shaft extends to the stator back iron through the other side wall of the shell and is contact-connected with the first and second mover permanent magnets, and the first and second connecting shafts are slidingly connected with the shell and the stator back iron; the stepping motor drives the first and second mover permanent magnets to rotate through the first connecting shaft, generates elastic force, and conducts the generated elastic force to the outside through the second connecting shaft.

[0006] Preferably, the first and second mover permanent magnets are two semicircular rings with the same size, the two semicircular rings are spliced into a cylindrical ring, and the axial magnetization directions of the two semicircular rings are opposite and the same.

[0007] Preferably, the first, second, third and fourth stator permanent magnets are semicircular ring bodies with the same size, the height of the semicircular ring bodies is half of the first mover permanent magnet, four semicircular ring bodies form a cylindrical ring with the same height as the first mover permanent magnet, the cylindrical ring is located outside the cylindrical ring formed by the first and second mover permanent magnets, there is a gap between the cylindrical ring formed by the first and second mover permanent magnets and the cylindrical ring formed by the first, second, third and fourth stator permanent magnets, the magnetization directions of the two stator permanent magnets on the same side and the two stator permanent magnets opposite to each other are opposite, the second and third stator permanent magnets are radially outwardly magnetized, and the first and fourth stator permanent magnets are radially inwardly magnetized.

[0008] Preferably, the inner cavity of the stator back iron is cylindrical, the height of the inner cavity is twice the height of the first stator permanent magnet, and the outer side of the first stator permanent magnet is attached to the inner wall of the stator back iron.

[0009] Preferably, the first connecting shaft is provided with a guide rail near the side close to the stepping motor, and the first connecting shaft can move in the guide rail.

[0010] Preferably, two sides of the shell are respectively fixed with a first support frame and a second support frame, the first connecting shaft and the second connecting shaft respectively penetrate the first support frame and the second support frame, and the adjustable stiffness magnetic force spring is placed in the wave power device through the first support frame and the second support frame.

[0011] Preferably, the first mover permanent magnet, the second mover permanent magnet, the second stator permanent magnet, the third stator permanent magnet and the fourth stator permanent magnet adopt a neodymium iron boron 30 material.

[0012] Preferably, the stator back iron adopts a silicon steel sheet DW360 material.

[0013] Preferably, the first connecting shaft and the second connecting shaft adopt an aluminum material.

[0014] Preferably, a plurality of strip-shaped holes are arranged on the side wall of the shell for reducing weight.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] 1. The magnetic force spring can adjust the corresponding stiffness through the rotation of the stepping motor, so that the stiffness of the magnetic force spring is adjusted between a negative stiffness and a positive stiffness, thereby adjusting the wave power device to absorb more energy.

[0017] 2. The maximum stroke of the magnetic force spring is twice the height of the stator, so that the magnetic force spring movement with large stroke can be realized, and the magnetic force spring is more suitable for the wave power device.

[0018] 3. The interaction between the permanent magnets can generate a larger elastic force, so that the magnetic force spring can be adjusted in a large range of elastic force, and the magnetic force spring is more suitable for the requirements of the wave power device. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the overall sectional view of the variable stiffness magnetic force spring of the present application.

[0020] Figure 2 is the electromagnetic overall structure schematic diagram of the variable stiffness magnetic force spring of the present application.

[0021] Figure 3 is the flux linkage situation schematic diagram of the magnetic force spring of the present application when the magnetic force spring is in maximum positive stiffness.

[0022] Figure 4 is the flux linkage situation schematic diagram of the magnetic force spring of the present application when the magnetic force spring is in maximum negative stiffness.

[0023] Figure 5 is the equivalent process schematic diagram of the magnetic force spring of the present application equivalent to a magnetic resistance.

[0024] Figure 6is the equivalent magnetic circuit diagram of the magnetic force spring at the equilibrium position under the maximum positive stiffness of the present application.

[0025] Figure 7 is the equivalent magnetic circuit diagram of the magnetic force spring at the maximum displacement under the maximum positive stiffness of the present application.

[0026] Figure 8 is the equivalent magnetic circuit diagram of the magnetic force spring at the equilibrium position under the maximum negative stiffness of the present application.

[0027] Figure 9 is the equivalent magnetic circuit diagram of the magnetic force spring at the maximum displacement under the maximum positive stiffness of the present application.

[0028] Figure 10 is the schematic diagram of the relationship between the elastic force and the displacement of the magnetic force spring of the present application under the maximum positive stiffness and the maximum negative stiffness. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0030] A magnetic force spring with adjustable stiffness, such as Figure 1As shown, the structure includes a housing 33, a magnetic force generating portion, and a stiffness adjustment portion. The magnetic force generating portion is located inside the housing 33 and includes a stator back iron 61, a first mover permanent magnet 51, a second mover permanent magnet 52, a first stator permanent magnet 41, a second stator permanent magnet 42, a third stator permanent magnet 43, and a fourth stator permanent magnet 44. The stiffness adjustment portion includes a first connecting shaft 22, a second connecting shaft 23, and a stepper motor 1. The stepper motor 1 is located outside the housing 33. The first mover permanent magnet 51 and the second mover permanent magnet 52 are rigidly connected to one end of the first connecting shaft 22, and the other end of the first connecting shaft 22 is rigidly connected to the stepper motor 1 via the track 21. The rotation of the stepper motor can drive the first mover permanent magnet 51 and the second mover permanent magnet 52 to rotate. The second connecting shaft 23 is slidably connected to the stator back iron 61, and is in contact with the first and second mover permanent magnets 51, 52. It moves with the movement of the first and second mover permanent magnets 51, 52, and transmits the generated elastic force to the outside. The entire magnetic spring is supported by the first support frame 31 and the second support frame 32. The magnetic spring generates elastic force in the following way: when the mover is in the equilibrium position, the stator exerts equal pulling force on the mover along the positive axial magnetization direction and the negative axial magnetization direction, so the elastic force generated by the magnetic spring is 0. When the permanent magnet deviates from the equilibrium position, if the stator permanent magnet exerts an attractive force on the spring mover, a negative stiffness is generated. If the stator permanent magnet exerts a repulsive force on the spring mover, a positive stiffness is generated.

[0031] The housing houses a stator back iron 61, a first mover permanent magnet 51, a second mover permanent magnet 52, a first stator permanent magnet 41, a second stator permanent magnet 42, a third stator permanent magnet 43, a fourth stator permanent magnet 44, a connecting shaft 21, and a stepper motor 1. The first mover permanent magnet 51 and the second permanent magnet 52 are rigidly connected to the first connecting shaft 22. The end of the first connecting shaft 22 is rigidly connected to the stepper motor 1. Rotation of the stepper motor 1 drives the first mover permanent magnet 51 and the second permanent magnet 52 to rotate. The end of the second connecting shaft 23 is in contact with and connected to the four stator permanent magnets; these four stator permanent magnets are rigidly connected to the stator back iron 61. The entire magnetic spring is supported by a first support frame 31 and a second support frame 32. The support frames are placed in the wave power generation device, generating an elastic force between the two ends.

[0032] like Figure 2 As shown, the mover has only one layer of permanent magnets, which consists of two first mover permanent magnets 51 and second mover permanent magnets 52 with opposite axial magnetization directions. The specific magnetization directions are as follows: Figure 2 As shown, one of the two permanent magnets is magnetized along the positive axial direction, and the other is magnetized along the negative axial direction. Figure 2The middle arrow indicates the magnetization direction. The stator is composed of two layers of permanent magnets, consisting of two pairs of permanent magnets with opposite radial magnetization directions: a first stator permanent magnet 41, a second stator permanent magnet 42, a third stator permanent magnet 43, and a fourth stator permanent magnet 44. The stator permanent magnets are four semi-cylindrical permanent magnets of equal size, each half the height of the rotor permanent magnets. The stator permanent magnets are arranged so that every two permanent magnets with opposite magnetization directions form a cylindrical ring, forming two layers of cylindrical rings. The magnetization direction of the permanent magnets in the upper cylindrical ring is opposite to that of the permanent magnets in the lower cylindrical ring. That is, if the permanent magnets in the upper layer are magnetized radially outward, then the permanent magnets in the same position in the lower layer are magnetized radially inward. The two layers of permanent magnets are arranged in a tightly fitting manner, ensuring that the elastic force generated by the interaction between the stator and rotor permanent magnets at the equilibrium position is zero.

[0033] The material of all permanent magnets is NdFeB 30, and the material of stator back iron 61 is silicon steel sheet DW360.

[0034] The stator back iron 61 is a hollow cylindrical ring, which can be thought of as a larger cylindrical ring with a smaller cylindrical ring hollowed out in the middle. The inner diameter of the smaller cylindrical ring is equal to the outer diameter of the stator permanent magnet. The height of the smaller cylindrical ring is twice that of the stator permanent magnet. This design minimizes magnetic flux leakage from the permanent magnet and improves permanent magnet utilization.

[0035] The stiffness adjustment section consists of a first connecting shaft 22, a second connecting shaft 23, and a stepper motor 1. The aluminum connecting shaft connects to the stepper motor, allowing the stepper motor to control its rotation. Simultaneously, under external force, the mover can move back and forth along the axis. A guide rail is provided on the side of the first connecting shaft 22 near the stepper motor 1 to constrain the movement of the first connecting shaft 22. This allows the stepper motor 1 to control only the rotation of the mover during its movement, thereby adjusting the angle of direct alignment between the intermediate mover and the stator.

[0036] When the mover is repelled by the external stator, the magnetic spring exhibits a positive stiffness characteristic. When the mover is in the center equilibrium position, the stiffness is positive and the displacement is zero, the repulsive forces of the two layers of the stator on the mover are equal and opposite in direction. Therefore, the elastic force generated by the spring is 0N, such as Figure 3 As shown in (a). When gradually moving from the neutral point to the starting point of maximum displacement, the repulsive force of the second stator permanent magnet 42 on the first mover permanent magnet 51 increases, and the attractive force of the first stator permanent magnet 41 on the first mover permanent magnet 51 decreases. This makes the elastic force of the mover gradually increase with the increase of displacement, showing the characteristic that the repulsive force increases with the increase of displacement, as shown in FIG. Figure 3 (b) shown.

[0037] When the mover is repelled by the stator, the magnetic spring exhibits positive stiffness characteristics. When the mover is in the center equilibrium position, the stiffness is positive and the displacement is zero. The attraction of the two layers of the stator particles to the mover particles is equal and opposite in direction. Therefore, the elastic force generated by the spring is 0N, such as Figure 4 As shown in (a). When gradually moving from the neutral point to the starting point of maximum displacement, the attraction force of the second stator permanent magnet 42 on the second mover permanent magnet 52 increases, and the repulsion force of the first stator permanent magnet 41 on the second mover permanent magnet 52 decreases. This makes the elastic force of the mover gradually increase with the increase of displacement, showing the characteristic that the attraction force increases with the increase of displacement, as shown in Figure 4 (b) shown.

[0038] In order to better analyze the elastic force generated by the magnetic spring, the magnetic spring is modeled by the magnetic network method. The magnetic network modeling can better analyze the change law of the spring output. The process of equivalent magnetic network is as follows Figure 5 As shown. The magnetic resistance from the first stator permanent magnet 41 to the second stator permanent magnet 42 is defined as R s The magnetic resistance between the first stator permanent magnet 41 and the first mover permanent magnet 51 is defined as R m,2 The direct magnetic resistance between the first mover permanent magnet 51 and the stator back iron 61 is defined as R a The direct magnetic resistance between the first mover permanent magnet 51 and the second mover permanent magnet 52 is defined as R path When the magnetic spring is at its maximum positive stiffness, the equivalent magnetic network when its displacement is zero is as follows: Figure 6 As shown. At this displacement, the motor is subjected to equal and opposite repulsive forces exerted by the stators on both sides of the magnetic circuit. Therefore, the force acting on the mover is zero. The equivalent magnetic network when the mover is at maximum displacement is as follows Figure 7 As the mover approaches this displacement, the repulsive force of the permanent magnets closer to the mover gradually increases, while the attractive force of the permanent magnets farther away from the mover gradually decreases. Therefore, the elastic force exerted by the mover is equal to the repulsive force.

[0039] When the magnetic spring is at its maximum negative stiffness, the equivalent magnetic network when its displacement is zero is as follows: Figure 8 As shown in Figure 2. When the mover is in equilibrium, the motor is subject to equal and opposite attractive forces from the stators on both sides of the magnetic circuit. Therefore, the force acting on the mover is zero. When the mover is at its maximum displacement, the equivalent magnetic network is as follows: Figure 9 As shown in Figure 1, as the mover approaches this displacement, the attractive force of the permanent magnets closer to the mover gradually increases, while the repulsive force of the permanent magnets farther away from the mover gradually decreases. Therefore, the elastic force exerted by the mover is equal to the attractive force.

[0040] Figure 10The relationship between the displacement and the elastic force of the spring in the maximum positive stiffness and the maximum negative stiffness is shown.

[0041] In summary, the present application is composed of a shell, a spring force generating part and a stiffness adjusting part, the spring force generating part is composed of a mover, a stator and a stator back iron, the stiffness adjusting part is composed of a stepping motor and two connecting shafts, the angle of magnetic force interaction between the mover and the stator is controlled by the stepping motor to generate different stiffness, the mover is composed of two cylindrical permanent magnets, one of which is magnetized in the positive axial direction, and the other is magnetized in the negative axial direction, the stator is composed of four cylindrical permanent magnets, two of which are magnetized in the positive radial direction, and the other two are magnetized in the negative radial direction, the stator permanent magnets are rigidly connected with the stator back iron. Compared with the traditional magnetic force spring, the proposed magnetic force spring changes the shape of the stator back iron, increases the stroke and thrust of the magnetic force spring, and is more suitable for use in wave power generation applications. At the same time, the reason for the elastic force of the magnetic force spring is described, which is more conducive to providing a guidance model for the optimization of the magnetic force spring in the future.

[0042] In the description of the present specification, the description of the terms "one embodiment", "example", "specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0043] The basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application.

Claims

1. A magnetic spring with adjustable stiffness for use in a point absorption wave power generation device, characterized in that: The invention comprises a housing (33), a magnetic force generating mechanism and a stiffness adjusting mechanism, wherein the magnetic force generating mechanism comprises a stator back iron (61), a first mover permanent magnet (51), a second mover permanent magnet (52), a first stator permanent magnet (41), a second stator permanent magnet (42), a third stator permanent magnet (43), and a fourth stator permanent magnet (44); the stiffness adjusting mechanism comprises a first connecting shaft (22), a second connecting shaft (23) and a stepping motor (1); the stator back iron (61) 1) is located in the housing (33), the first mover permanent magnet (51), the second mover permanent magnet (52), the first stator permanent magnet (41), the second stator permanent magnet (42), the third stator permanent magnet (43), and the fourth stator permanent magnet (44) are installed in the cavity of the stator back iron (61), and the first stator permanent magnet (41), the second stator permanent magnet (42), the third stator permanent magnet (43), and the fourth stator permanent magnet (44) are wrapped in the first mover permanent magnet ( 51), and the outside of the second mover permanent magnet (52); the stepper motor (1) is located outside the housing (33), one end of the first connecting shaft (22) is connected to the stepper motor (1), and the other end passes through a side wall of the housing (33) and extends into the cavity of the stator back iron (61), and is rigidly connected to the first mover permanent magnet (51) and the second mover permanent magnet (52); the second connecting shaft (23) is located on the side opposite to the first connecting shaft (22), and one end thereof passes through the other side wall of the housing (33) The stepper motor (1) extends into the stator back iron (61), and the end face is in contact with the first mover permanent magnet (51) and the second mover permanent magnet (52), and the first connecting shaft (22) and the second connecting shaft (23) are both slidably connected to the housing (33) and the stator back iron (61); the stepper motor (1) drives the first mover permanent magnet (51) and the second mover permanent magnet (52) to rotate through the first connecting shaft (22), thereby generating elastic force, and the generated elastic force is transmitted to the outside through the second connecting shaft (23).

2. The adjustable stiffness magnetic spring used in a point absorption wave power generation device according to claim 1, characterized in that: The first mover permanent magnet (51) and the second mover permanent magnet (52) are two semicircular rings of the same size, which are spliced ​​into a cylindrical ring with opposite axial magnetization directions and the same size.

3. The adjustable stiffness magnetic spring used in a point absorption wave power generation device according to claim 2, characterized in that: The first stator permanent magnet (41), the second stator permanent magnet (42), the third stator permanent magnet (43), and the fourth stator permanent magnet (44) are semicircular rings of the same size, and their height is half of that of the first mover permanent magnet (51). The four semicircular rings form a cylindrical ring with the same height as the first mover permanent magnet (51). The cylindrical ring is located outside the cylindrical ring of the first mover permanent magnet (51) and the second mover permanent magnet (52). There is a gap between the cylindrical ring and the cylindrical ring of the first mover permanent magnet (51) and the second mover permanent magnet (52). The magnetization directions of the two stator permanent magnets on the same side and the two stator permanent magnets facing each other are opposite.

4. The adjustable stiffness magnetic spring for use in a point absorption wave power generation device according to claim 3, characterized in that: The inner cavity of the stator back iron (61) is cylindrical, and the inner cavity height is twice that of the first stator permanent magnet (41). The outer side of the first stator permanent magnet (41) is in contact with the inner wall of the stator back iron (61).

5. The adjustable stiffness magnetic spring for use in a point absorption wave power generation device according to claim 1, characterized in that: A guide rail is provided on the side of the first connecting shaft (22) close to the stepping motor (1), and the first connecting shaft (22) is movable within the guide rail.

6. The adjustable stiffness magnetic spring used in a point absorption wave power generation device according to claim 1, characterized in that: A first support frame (31) and a second support frame (32) are respectively fixed to both sides of the shell (33); a first connecting shaft (22) and a second connecting shaft (23) respectively penetrate the first support frame (31) and the second support frame (32); and an adjustable stiffness magnetic spring is placed in the wave power generation device through the first support frame (31) and the second support frame (32).

7. The adjustable stiffness magnetic spring for use in a point absorption wave power generation device according to claim 1, characterized in that: The first mover permanent magnet (51), the second mover permanent magnet (52), the second stator permanent magnet (42), the third stator permanent magnet (43) and the fourth stator permanent magnet (44) are made of neodymium iron boron 30 material.

8. The adjustable stiffness magnetic spring used in a point absorption wave power generation device according to claim 1, characterized in that: The stator back iron (61) is made of silicon steel sheet DW360.

9. The adjustable stiffness magnetic spring used in a point absorption wave power generation device according to claim 1, characterized in that: The first connecting shaft (22) and the second connecting shaft (23) are made of aluminum.

10. The adjustable stiffness magnetic spring used in a point absorption wave power generation device according to claim 1, characterized in that: A plurality of strip-shaped holes are provided on the side wall of the housing (33).

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