Multi-pole coil magneto-rheological brake and testing device

Abstract

The invention provides a multi-pole coil magnetorheological brake and a testing device, and belongs to the technical field of magnetorheological fluid brakes. Comprising a brake shell, transmission shafts and brake shafts. The transmission shaft penetrates through the brake shell; one end of the transmission shaft in the brake shell is connected with the transmission cylinder; a braking cylinder is arranged below the transmission cylinder, and a cavity used for storing magnetorheological fluid is formed between the transmission cylinder and the braking cylinder. One end of the brake cylinder away from the transmission cylinder is connected with the brake shaft; a multi-stage coil is fixed on the brake shaft, extends and is wound on the brake cylinder; meanwhile, a brake disc of a tooth-shaped structure is fixed to the end, away from the transmission cylinder, of the brake shaft. And the brake disc realizes braking under the cooperation of the multi-stage coil and the magnetorheological fluid. The magnetic field distribution of the working area can be improved by adopting the multi-stage coils, the tooth-shaped brake disc is matched, the braking torque generated by the brake disc is increased, and then effective braking is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetorheological fluid brakes, and in particular relates to a multi-pole coil magnetorheological brake and a testing device. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Magnetorheological fluid is a new type of intelligent material. It is in the state of Newtonian fluid when there is no external magnetic field. Under the action of an external magnetic field, it can transform into a solid or solid-like state within milliseconds. This transformation is reversible, and its mechanical properties can be changed by adjusting the magnitude of the magnetic field. At the same time, magnetorheological fluid has the advantages of large shear yield stress and rapid response, and has been widely used in automotive braking, aerospace, medical equipment and other fields.

[0004] However, most of the current magnetorheological brakes increase the working area by increasing the volume and using multiple discs, and increase the braking torque by increasing the working area. On the one hand, this method will greatly increase the body area of ​​the magnetorheological brake, and the corresponding weight will also increase, increasing the manufacturing cost; on the other hand, increasing the working area is likely to cause problems such as excessive temperature and excessive shear strain rate during the braking process, so the braking effect is not good. Summary of the invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a multi-pole coil magnetorheological brake and a testing device, which can improve the magnetic field distribution in the working area by adopting a multi-level coil, and cooperate with a toothed brake disc to increase the braking torque generated by the brake disc, thereby achieving effective braking.

[0006] To achieve the above objectives, one or more embodiments of the present invention provide the following technical solutions:

[0007] A first aspect of the present invention provides a multi-pole coil magnetorheological brake.

[0008] A multi-pole coil magnetorheological brake comprises: a brake housing with a hollow structure, a transmission shaft and a brake shaft;

[0009] The transmission shaft is arranged through the brake housing;

[0010] One end of the transmission shaft located inside the brake housing is connected to the transmission cylinder; a brake cylinder is arranged below the transmission cylinder, and a cavity is formed between the transmission cylinder and the brake cylinder for storing magnetorheological fluid;

[0011] One end of the brake cylinder away from the transmission cylinder is connected to the brake shaft; a multi-stage coil is fixed on the brake shaft, and the multi-stage coil extends and is wound around the brake cylinder; at the same time, a brake disc with a toothed structure is fixed on one end of the brake shaft away from the transmission cylinder; the brake disc achieves braking with the cooperation of the multi-stage coil and magnetorheological fluid.

[0012] Furthermore, the brake shaft is also arranged to penetrate the brake housing, and the penetration position of the brake shaft is opposite to the transmission shaft.

[0013] Furthermore, a left end cover and a right end cover are respectively arranged above the brake housing; the brake housing cooperates with the left end cover and the right end cover to form a closed space.

[0014] Furthermore, the left end cover is provided with a lead hole, and the multi-stage coil passes through the lead hole and is connected to a power source outside the brake housing.

[0015] Furthermore, a groove is provided in the cavity, and a nitrile rubber sealing ring is placed in the groove for sealing.

[0016] Furthermore, the brake disc with the toothed structure includes a plurality of toothed chains, and a plurality of toothed balls are provided on each toothed chain.

[0017] Furthermore, the current values ​​passed through adjacent coils of the multi-stage coil are equal in magnitude and opposite in direction.

[0018] A second aspect of the present invention provides a multi-pole coil magnetorheological brake testing device.

[0019] A multi-pole coil magnetorheological brake testing device comprises a power transmission module and a data acquisition and control module.

[0020] Further, the power transmission module includes a servo motor, a coupling, a torque sensor and a magnetorheological brake connected in sequence;

[0021] The servo motor is used to control the rotation speed and generate torque; the coupling is connected to the servo motor to maintain the same rotation speed as the servo motor; the torque sensor is used to detect the braking torque generated by the magnetorheological brake.

[0022] Furthermore, the data acquisition and control module includes a speed controller, a low-voltage power supply, a temperature sensor, a temperature transmitter, a controllable current source, a torque sensor, a torque transmitter, a data acquisition card and a computer device.

[0023] One or more of the above technical solutions have the following beneficial effects:

[0024] The present invention stores magnetorheological fluid in the cavity formed by the transmission cylinder and the brake cylinder; one end of the brake cylinder away from the transmission cylinder is connected to the brake shaft, and a multi-stage coil is fixed on the brake shaft; at the same time, a brake disc with a toothed structure is fixed on the brake shaft; the brake disc achieves braking under the cooperation of the multi-stage coil and the magnetorheological fluid. On the one hand, the present invention only needs to control the physical state of the magnetorheological fluid through the multi-stage coil, and can achieve braking with the toothed brake disc, without adding a working area, thus avoiding material waste; on the other hand, the present invention provides an extrusion stress through the toothed brake disc to increase the braking torque of the brake, and uses a multi-stage coil to improve the magnetic field distribution in the working area, so that the braking torque generated by the brake disc can be increased more quickly and effectively, thereby achieving effective braking.

[0025] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0027] Figure 1 This is a schematic diagram of the overall structure of a multi-pole coil magnetorheological brake in Embodiment 1 of the present invention.

[0028] Figure 2 Schematic diagram of the structure of a brake disc with a toothed structure in Embodiment 1 of the present invention.

[0029] Figure 3 Schematic diagram of the magnetic circuit when the multi-stage coil in the first embodiment of the present invention is working.

[0030] Figure 4 It is a schematic diagram of the structure of the power transmission module in the second embodiment of the present invention.

[0031] Figure 5 The figure is a schematic diagram of the structure of a multi-pole coil magnetorheological brake testing device in the second embodiment of the present invention.

[0032] In the figure, 1 is a brake shaft; 2 is a left end cover; 3 is an oiler; 4 is a transmission cylinder; 5 is a right end cover; 6 is a transmission shaft; 7 is a bearing cover; 8 is a multi-stage coil; 9 is a brake cylinder; 10 is a nitrile rubber sealing ring; 11 is a cavity; 12 is a toothed chain; and 13 is a toothed ball. DETAILED DESCRIPTION

[0033] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0034] It should be noted that the terms used herein are for describing specific embodiments only and are not intended to be limiting of exemplary embodiments according to the present invention.

[0035] In the absence of conflict, the embodiments of the present invention and the features of the embodiments may be combined with each other.

[0036] Embodiment 1

[0037] This embodiment discloses a multi-pole coil magnetorheological brake.

[0038] Reference Figure 1 , a multi-pole coil magnetorheological brake, comprising: a brake housing with a hollow structure, a transmission shaft and a brake shaft;

[0039] The transmission shaft 6 is arranged through the brake housing;

[0040] One end of the transmission shaft 6 located inside the brake housing is connected to the transmission cylinder 4; a brake cylinder 9 is arranged below the transmission cylinder 4, and a cavity 11 is formed between the transmission cylinder 4 and the brake cylinder 9 for storing magnetorheological fluid;

[0041] One end of the brake cylinder 9 away from the transmission cylinder 4 is connected to the brake shaft 1; a multi-stage coil 8 is fixed on the brake shaft 1, and the multi-stage coil 8 extends and is wound around the brake cylinder 9; at the same time, a brake disc with a toothed structure is fixed to one end of the brake shaft 1 away from the transmission cylinder 4; the brake disc achieves braking with the cooperation of the multi-stage coil 8 and the magnetorheological fluid.

[0042] Based on the multi-pole coil magnetorheological brake provided by the present invention, the magnetic field distribution in the working area can be improved by using a multi-level coil, and the braking torque generated by the brake disc can be increased in combination with a toothed brake disc, thereby achieving effective braking. In order to facilitate the understanding of the technical solution of the present invention, the specific implementation steps in the technical solution of the present invention are further explained and illustrated below.

[0043] Reference Figure 1 One end of the transmission shaft 6 located inside the brake housing is connected to the transmission cylinder 4. Specifically, the transmission cylinder 4 and the transmission shaft 6 are connected together by screws. The transmission shaft 6 is used to transmit the torque into the magnetorheological brake through the transmission cylinder 4.

[0044] The brake shaft 1 is also arranged to penetrate the brake housing, and the penetration position of the brake shaft 1 is opposite to the transmission shaft 6; similarly, the brake shaft 1 and the brake cylinder 9 are also fixed together by screws.

[0045] Reference Figure 1 A left end cover 2 and a right end cover 5 are respectively arranged above the brake housing; on this basis, the brake housing cooperates with the left end cover 2 and the right end cover 5 to form a closed space.

[0046] A multi-level coil 8 is fixed on the brake shaft 1, and the fixed multi-level coil 8 is extended and wound on the brake cylinder 9. At the same time, a lead hole is provided on the left end cover 2, and the multi-level coil 8 passes through the lead hole to connect with the power supply outside the brake housing. When the multi-level coil is energized, the magnetic field generated passes through the working range of the magnetorheological fluid. Under the action of the magnetic field, the magnetorheological fluid undergoes a magnetorheological effect, and the magnetorheological fluid changes from a Newtonian fluid state to a solid or quasi-solid state. Due to the relative movement of the transmission cylinder 4 and the brake cylinder 9, a shear stress is generated on the magnetorheological fluid, thereby providing a braking torque for the magnetorheological brake. Since the movement direction of the magnetorheological brake and the convergent film formed by the inclined surface of the tooth structure help to generate a pressure generation mechanism in the magnetorheological fluid, the resistance generated by the magnetorheological brake shown in the present invention under the proposed situation can exceed that of the traditional cylindrical brake.

[0047] When the magnetorheological brake is used to generate braking torque, a stable static magnetic field needs to be generated in the working range of the magnetorheological brake, which requires that the material of the area where the magnetic lines of force pass should have high magnetic permeability and magnetic saturation strength. The magnetorheological brake transmits the braking force under the combined action between the transmission cylinder 4 and the brake cylinder 9; at the same time, the magnetorheological fluid will generate friction between the two cylinders, so the transmission cylinder 4 and the brake cylinder 9 should have high shear strength and good wear resistance. The magnetic lines of force pass through the transmission disc and the brake disc, so materials with high magnetic permeability should be selected. Considering the mechanical properties and cost-effectiveness of the materials, in this embodiment, No. 20 low carbon steel is selected as the material of the brake component.

[0048] Reference Figure 1 A cavity 11 for storing magnetorheological fluid is formed between the transmission cylinder 4 and the brake cylinder 9 . Specifically, a cavity 11 with a thickness of 2 mm is set between the brake cylinder 9 and the transmission cylinder 4 , and the magnetorheological fluid can be injected into the cavity 11 through the oiler 3 .

[0049] A groove is provided in the cavity 11, and a nitrile rubber sealing ring 10 is placed in the groove for sealing. Specifically, an O-type nitrile rubber ring is placed between the transmission cylinder 4 and the brake cylinder 9, and the sealing ring is placed in a groove reserved in advance. In order to prevent leakage of magnetorheological fluid, a certain amount of sealing silicone can also be applied to assist in achieving the sealing purpose.

[0050] The multi-pole coil magnetorheological brake provided by the present invention further comprises a bearing cover 7 which can be connected to the right end cover by bolts. The arrangement of the bearing cover 7 can prevent the bearing from sliding in the axial direction.

[0051] Reference Figure 2 The toothed brake disc includes a plurality of toothed chains 12 , and a plurality of toothed balls 13 are provided on each toothed chain 12 .

[0052] Reference Figure 3 , the current values ​​passed through the adjacent coils of the multi-level coil 8 are equal in magnitude and opposite in direction; thus, the magnetic poles generated by the two adjacent coils are opposite, and the generated magnetic field forms a loop, which is more evenly distributed in the working range of the magnetorheological fluid. It should be noted that when the current is passed through the multi-level coil, the present embodiment is not set arbitrarily, but firstly, according to the basic law of the magnetic circuit, the magnetic circuit magnetic resistance calculation formula of the magnetorheological brake is derived by analytical method, and the magnetic circuit modeling analysis of the magnetorheological brake is combined to obtain the magnetomotive force calculation formula; then, based on the Bingham plasticity model, the mathematical model of the braking torque of the magnetorheological brake is derived; finally, based on the finite element method, a magnetic circuit simulation of a multi-pole coil magnetorheological brake is carried out to complete the optimization design of the main structural parameters; on this basis, the relationship between the coil current and the working gap magnetic field strength is analyzed, specifically:

[0053] When current is passed through the multi-stage coil, the present embodiment is not set arbitrarily, but firstly, according to the basic law of magnetic circuit, the magnetic circuit magnetic resistance calculation formula of the magnetorheological brake is derived by analytical method, combined with the magnetic circuit modeling analysis of the magnetorheological brake, the braking part of the magnetorheological brake is composed of a magnetic conductor and a magnetorheological fluid. From the magnetic circuit planning diagram, it can be seen that the magnetic lines pass through these components to form a loop. No. 20 low carbon steel is selected as the brake component material, and its magnetic permeability is set to μ 1 , assuming the effective length of the brake cylinder magnetic resistance is L 1 , the cross-sectional area is S 1 , the effective magnetic resistance length of the transmission cylinder is L 2 , the cross-sectional area is S 2 The magnetic permeability of the magnetorheological fluid is set to μ 2 , the working gap is set to 2mm, and the effective length is assumed to be L 3 , the cross-sectional area is S 3 The magnetic flux Φ required for the working space, N is the number of coil turns, I is the number of coil turns, the unit is A, and the calculation formula for the magnetomotive force is:

[0054]

[0055] Among them, R m represents the magnetomotive force. Further, the magnetic resistance of the conductor part can be obtained, that is:

[0056]

[0057] Among them, R m1 Represents the magnetic resistance of the conductor part. Further, the magnetic resistance of the magnetorheological fluid part is:

[0058]

[0059] Among them, T m2 Represents the magnetic resistance of the magnetorheological fluid. Since the magnetic conductor and the magnetorheological fluid in the magnetic circuit are connected in series, the total magnetic resistance is T total :

[0060] R total =R m1 +R m2 ;

[0061] Subsequently, the mathematical model of the braking torque of the magnetorheological brake was derived based on the Bingham plasticity model. The Bingham plasticity model describes the rheological properties of materials with yield stress, and its constitutive equation is:

[0062]

[0063] Where τ represents the shear stress, τ y represents the yield stress, η represents the plastic viscosity, In the magnetorheological brake, the mechanical behavior of the magnetorheological fluid conforms to this model, and changes in the magnetic field will change its yield stress τ y , which in turn affects the overall mechanical properties.

[0064] Assume that the transmission cylinder rotates at an angular velocity ω, the brake cylinder is stationary, and the working gap thickness is h = 2mm. According to Newton's viscosity law, the velocity distribution can be approximated as linear, that is:

[0065] u(y)=ωy;

[0066] Where y is the distance from the surface of the brake cylinder to the surface of the transmission cylinder, and 0≤y≤h, the velocity gradient is:

[0067]

[0068] Furthermore, the velocity gradient is substituted into the constitutive equation of the Bingham plasticity model, namely:

[0069]

[0070] Yield stress τ of magnetorheological fluid y It is related to the magnetic field strength B and can usually be expressed as:

[0071] τ y=kB n ;

[0072] Among them, k and n are constants related to the characteristics of magnetorheological fluid, and the magnetic field intensity B is related to the coil current I. At the radius r, take a small annular area dA = 2πrdr, and the friction force dF = τdA acting on this small area. The braking torque T is the torque integral of the friction force on the center of the brake shaft, that is:

[0073]

[0074] Among them, r 1 、r 2 are the inner and outer radii of the working gap respectively.

[0075] When τ ≥ τ y hour:

[0076]

[0077] When τ<τ y hour:

[0078]

[0079] Through the above steps, combined with the Bingham plasticity model, the working principle and geometric parameters of the magnetorheological brake, the mathematical model of the braking torque of the magnetorheological brake is derived. This model reflects the relationship between the braking torque and factors such as magnetorheological fluid characteristics, magnetic field intensity, and rotation speed.

[0080] Embodiment 2

[0081] This embodiment discloses a multi-pole coil magnetorheological brake testing device.

[0082] In order to prevent the magnetic field from being transmitted in the non-working area and make the magnetic lines of force pass through the working area of ​​the brake as much as possible, the transmission shaft plays the role of transmitting torque, and the brake shaft plays the role of providing braking torque. Therefore, the material needs to have a large shear strength. The brake shaft, transmission shaft, left end cover, oiler, right end cover, bearing cover and magnetic isolation plate are all made of stainless steel. Cyanoacrylate is used to adhere the magnetic isolation piece and the brake disc to prevent leakage.

[0083] In order to verify the performance of magnetorheological brake, a test device was built as an experimental platform.

[0084] Reference Figure 4 , Figure 5 , a multi-pole coil magnetorheological brake testing device, including: a power transmission module and a data acquisition and control module.

[0085] The power transmission module includes a servo motor, a coupling, a torque sensor, and a magnetorheological brake connected in sequence. The servo motor is used to control the speed and generate torque; the coupling is connected to the servo motor to maintain the same speed as the servo motor, which can be used to alleviate the impact caused by system operation and installation errors; the torque sensor is used to detect the braking torque generated by the magnetorheological brake; the magnetorheological brake is the analysis object. These devices are fixed on the desktop through the base frame.

[0086] Reference Figure 5 ,The data acquisition and control module includes a speed controller, a low voltage power supply, a temperature sensor, a temperature transmitter, a controllable current source, a torque sensor, a torque transmitter, a data acquisition card and a computer device.

[0087] Among them, the speed controller is connected to the servo motor through a wire, and the speed of the servo motor can be adjusted by a computer device. The low-voltage power supply is used to power the temperature transmitter and the torque transmitter; the temperature sensor is used to measure the temperature of the magnetorheological fluid, that is, the internal temperature of the magnetorheological brake is measured by the temperature sensor, and the braking performance of the magnetorheological brake at different temperatures is detected; and the temperature transmitter converts it into a voltage signal and outputs it to the acquisition card. The controllable current source can change the current size of the excitation coil to adjust the brake torque. The torque transmitter is used to convert the pulse frequency signal into a voltage signal and output it to the acquisition card.

[0088] In this embodiment, the experimental process mainly includes controlling the rotation speed to be constant, changing the coil current in the brake to detect the braking performance of the magnetorheological brake under different current sizes; and keeping the multi-stage coil current inside the magnetorheological brake constant, and changing the brake torque at different rotation speeds of the servo motor; the performance of the magnetorheological fluid will also change with increasing temperature, and a temperature sensor is used to detect changes in the braking performance of the magnetorheological brake with temperature changes.

[0089] Those skilled in the art should understand that the modules or steps of the present invention described above can be implemented by a general-purpose computer device, or alternatively, they can be implemented by a program code executable by a computing device, so that they can be stored in a storage device and executed by the computing device, or they can be made into individual integrated circuit modules, or multiple modules or steps therein can be made into a single integrated circuit module for implementation. The present invention is not limited to any specific combination of hardware and software.

[0090] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A multi-pole coil magnetorheological brake, characterized in that: include: Brake housing, transmission shaft and brake shaft in hollow structure; The transmission shaft is arranged through the brake housing; One end of the transmission shaft located inside the brake housing is connected to the transmission cylinder; a brake cylinder is arranged below the transmission cylinder, and a cavity is formed between the transmission cylinder and the brake cylinder for storing magnetorheological fluid; One end of the brake cylinder away from the transmission cylinder is connected to the brake shaft; a multi-stage coil is fixed on the brake shaft, and the multi-stage coil extends and is wound around the brake cylinder; at the same time, a brake disc with a toothed structure is fixed on one end of the brake shaft away from the transmission cylinder; the brake disc achieves braking with the cooperation of the multi-stage coil and magnetorheological fluid.

2. A multi-pole coil magnetorheological brake according to claim 1, characterized in that: The brake shaft is also arranged to penetrate the brake housing, and the penetration position of the brake shaft is opposite to the transmission shaft.

3. A multi-pole coil magnetorheological brake as claimed in claim 1, characterized in that: A left end cover and a right end cover are respectively arranged above the brake housing; the brake housing cooperates with the left end cover and the right end cover to form a closed space.

4. A multi-pole coil magnetorheological brake as claimed in claim 3, characterized in that: The left end cover is provided with a lead hole, and the multi-stage coil passes through the lead hole and is connected to a power source outside the brake housing.

5. A multi-pole coil magnetorheological brake as claimed in claim 1, characterized in that: A groove is arranged in the cavity, and a nitrile rubber sealing ring is placed in the groove for sealing.

6. A multi-pole coil magnetorheological brake as claimed in claim 1, characterized in that: The toothed brake disc comprises a plurality of toothed chains, and a plurality of toothed balls are arranged on each toothed chain.

7. A multi-pole coil magnetorheological brake as claimed in claim 1, characterized in that: The current values ​​flowing into adjacent coils of the multi-stage coil are equal in magnitude and opposite in direction.

8. A multi-pole coil magnetorheological brake test device, characterized in that: include: Power transmission module and data acquisition and control module.

9. A multi-pole coil magnetorheological brake testing device as claimed in claim 8, characterized in that: The power transmission module includes a servo motor, a coupling, a torque sensor and a magnetorheological brake connected in sequence; The servo motor is used to control the rotation speed and generate torque; the coupling is connected to the servo motor to maintain the same rotation speed as the servo motor; the torque sensor is used to detect the braking torque generated by the magnetorheological brake.

10. A multi-pole coil magnetorheological brake testing device as claimed in claim 8, characterized in that: The data acquisition and control module includes a speed controller, a low-voltage power supply, a temperature sensor, a temperature transmitter, a controllable current source, a torque sensor, a torque transmitter, a data acquisition card and a computer device.

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