A hot extruded volume percentage bearing type magnetorheological fluid brake

Abstract

The invention discloses a heat extrusion volume percentage bearing bush type magnetorheological fluid brake, comprising a brake housing, a brake shaft and a base; the part of the brake shaft located in the brake housing is expanded to form a brake section; an excitation coil and a magnetic isolation friction ring are arranged in the brake cylinder, a containing groove is arranged on the brake section, and a friction top block, a guide column and a shape memory alloy spring are arranged in the containing groove; a bearing bush is arranged outside the brake section, an axial hole is opened at the right end of the brake shaft, and an oil guide hole is opened in the middle of the brake section, the inner end of the oil guide hole is connected to the axial hole, and the middle part is connected to the containing groove; a filter is arranged at the outer end of the oil guide hole, and the bearing bush is connected to the filter by sliding fit; a magnetorheological fluid is filled between the outer wall of the bearing bush and the inner wall of the brake housing, and silicone oil is filled in the axial hole, the oil guide hole, the connecting hole and the containing groove. The invention can ensure the stability and reliability of the brake in a high temperature environment, ensure the braking performance, and improve the braking effect.

Description

Technical Field

[0001] The invention relates to the technical field of brakes, and in particular to a thermally extruded volume percentage bearing bush type magnetorheological fluid brake. Background Art

[0002] Magnetorheological fluid is a magnetic intelligent material, which is mainly composed of magnetic particles and base fluid (usually silicone oil). It is controlled by an external magnetic field and exhibits the properties of Newtonian fluid in the absence of an external magnetic field. After the addition of a magnetic field, the viscosity of the magnetorheological fluid changes by several orders of magnitude, exhibiting the properties of a Bingham plastic fluid. The entire change process is rapid, reversible and easy to operate.

[0003] Based on the above properties of magnetorheological fluid, it has broad application prospects in the field of clutches and brakes; for example, the "magnetorheological brake" disclosed in Chinese patent CN103453053A uses an excitation coil for magnetic braking under normal working conditions to provide controllable power. When the excitation coil fails or loses power, the excitation coil magnetic braking mode is quickly switched to the permanent magnet magnetic braking mode through the action of the stretching spring group and the pressure oil in the sealing chamber to ensure the continuation of the braking force of the magnetorheological brake. For example, the "shape memory alloy compensated magnetorheological brake" disclosed in CN205423620U injects magnetorheological fluid into the annular working chamber, generates a magnetic field by energizing the excitation coil to act on the magnetorheological fluid to generate a braking torque, and when the temperature rises, the shape memory alloy spring stretches and pushes the slider to act on the brake housing, thereby generating a braking torque. However, when the magnetorheological fluid reaches magnetic saturation, the braking torque it generates cannot continue to increase; and when the performance of the magnetorheological fluid decreases, the braking torque it generates will also decrease, thereby reducing the braking performance. For example, CN103089863A discloses a radial extrusion magnetorheological fluid brake, which is relatively simple in structure and can provide a large braking torque; however, in a high temperature environment, the stability and reliability of the torque transmission are poor.

[0004] In summary, the above-mentioned brake based on magnetorheological fluid is prone to degradation of magnetorheological fluid performance or even failure in a high temperature environment, resulting in poor brake stability and poor braking effect. How to solve the problem that the above-mentioned brake based on magnetorheological fluid does not take into account the poor brake stability and poor braking effect in a high temperature environment, and ensure the high performance operation of the magnetorheological fluid brake, has become a technical problem that technicians in this field continue to solve. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to solve the problem that the existing magnetorheological fluid brake is prone to deterioration of magnetorheological fluid performance in a high temperature environment, thereby causing poor brake stability and poor braking effect, and to provide a hot extruded volume percentage bearing type magnetorheological fluid brake, which can ensure the stability and reliability of the brake in a high temperature environment, ensure the braking performance, and improve the braking effect.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows: a hot extruded volume percentage bearing type magnetorheological fluid brake, including a brake housing, a brake shaft and a base; the brake housing includes a left end cover, a brake cylinder and a right end cover which are connected in sequence, and the base is fixedly connected to the middle part of the brake cylinder; the right end of the brake shaft passes through the left end cover and extends into the brake housing, and is rotatably connected to the left end cover and the right end cover through a bearing, the part of the brake shaft located in the brake housing is expanded to form a brake section, and there is a gap between the side wall of the brake section and the inner wall of the brake housing; on the inner side of the brake cylinder, coil grooves are respectively provided around it near the two ends, and an excitation coil is respectively provided in the two coil grooves; it is characterized in that: on the inner side of the brake cylinder, a magnetic isolation friction ring is respectively provided at the position corresponding to the two coil grooves, the magnetic isolation friction ring is fixedly connected to the brake cylinder, and the excitation coil is enclosed in the coil groove;

[0007] Near both ends of the braking section, corresponding to the positions of the two magnetic isolation friction rings, a number of receiving grooves are respectively provided, and the positions of the receiving grooves near the two ends of the braking section correspond, wherein the receiving grooves are evenly distributed around the braking section, and the depth direction of the receiving grooves is consistent with the radial direction of the braking section; a friction top block, a guide column and a shape memory alloy spring are provided in the receiving groove; the guide column is arranged along the radial direction of the braking section, and its inner end is fixedly connected to the groove bottom of the receiving groove; the friction top block is connected to the outer end of the guide column by sliding fit, and a first sealing ring is provided between its side wall and the side wall of the receiving groove; the shape memory alloy spring is located between the friction top block and the groove bottom of the receiving groove, and is sleeved on the guide column, and its two ends are fixedly connected to the friction top block and the groove bottom of the receiving groove, respectively. In the initial state, under the action of the shape memory alloy spring, the friction top block is located in the receiving groove;

[0008] On the outside of the braking section of the brake shaft, several arc-shaped bearing shells are arranged around it. In the initial state, the bearing shell is fitted with the braking section, and there is a gap between its outer wall and the magnetic isolation friction ring, and the adjacent two sides of two adjacent bearing shells are fitted together to form a sleeve; a rubber sheet is arranged on the outside of the fitting part of two adjacent bearing shells, and the two adjacent bearing shells are connected by the rubber sheet; wherein, the number of the bearing shells is consistent with the number of the receiving grooves at one end of the braking section, and the two ends of the bearing shells extend to the outside of the two receiving grooves at the corresponding positions respectively, and the middle part of the bearing shell in the arc direction is directly opposite to the friction top block in the receiving groove;

[0009] An axial hole is provided at the right end of the brake shaft, the inner end of the axial hole extends to the middle of the brake segment, and the outer end is closed by a plug; in the middle of the brake segment, a plurality of oil guide holes are provided around it, the oil guide holes are arranged along the radial direction of the brake segment, and the positions of the oil guide holes correspond to the positions of the receiving grooves at one end of the brake segment; the inner end of the oil guide hole extends to communicate with the axial hole, and the middle part thereof is connected with the two receiving grooves at corresponding positions through a connecting hole; a filter is provided at the outer end of the oil guide hole, and a gap is provided between the filter and the inner wall of the brake housing; a through hole is provided on the bearing shell at the position corresponding to the filter, and the bearing shell is sleeved on the filter through the through hole and is connected with the filter in a sliding fit;

[0010] The gap between the outer wall of the bearing bush and the inner wall of the brake housing is filled with magnetorheological fluid, and the shaft hole, the oil guide hole, the connecting hole and the containing groove are filled with silicone oil.

[0011] Furthermore, the filter includes a cylindrical shell and a filter membrane, one end of the cylindrical shell is fixedly connected to the braking section and communicated with the oil guide hole, and the other end extends to form an offset with the magnetic isolation friction ring, and has a gap with the inner wall of the brake cylinder; the bearing is connected to the cylindrical shell in a sliding fit, wherein a second sealing ring is provided between the bearing and the cylindrical shell, and the second sealing ring is fixedly connected to the bearing.

[0012] Furthermore, a guide rod is provided on the inner side of the friction top block, and a guide hole is provided on the guide column along its axial direction. The guide rod extends into the guide hole and is connected with the guide column in a sliding manner.

[0013] Furthermore, a retaining ring is provided at both ends of the braking segment, the inner side of the retaining ring is fixedly connected to the braking segment, and the outer side extends to form an offset with the magnetic isolation friction ring; the two ends of the bearing are respectively fitted with the two retaining rings and can move closely along the radial direction of the braking segment along the retaining rings.

[0014] Furthermore, a liquid injection hole is provided on the brake cylinder, the liquid injection hole is communicated with the inside of the brake housing, and a liquid injection screw plug is matched in the liquid injection hole.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1. After the excitation coil is energized, the magnetorheological fluid produces a magnetorheological effect under the action of the magnetic field, braking the braking section; when the magnetorheological fluid heats up, it can be quickly transferred to the shape memory alloy spring through the silicone oil. When the silicone oil temperature reaches the deformation temperature of the shape memory alloy spring, the shape memory alloy spring can stretch, pushing the bearing to squeeze the magnetorheological fluid, so that part of the base fluid in the magnetorheological fluid flows into the oil guide hole, and the silicone oil in the oil guide hole additionally pushes the friction top block, thereby pushing the bearing to squeeze the magnetorheological fluid.

[0017] 2. After the shape memory alloy spring is stretched, it further pushes the friction top block, and pushes the bearing through the top block, so that the bearing squeezes the magnetorheological fluid, so that the base liquid (silicone oil) in the magnetorheological fluid passes through the filter and enters the oil guide hole according to the percentage, thereby increasing the percentage concentration of magnetic particles in the magnetorheological fluid in the working gap, thereby enhancing the magnetorheological effect of the magnetorheological fluid, avoiding the decrease of the braking torque transmitted by the magnetorheological fluid due to the increase in temperature, and ensuring the reliability and stability of braking.

[0018] 3. As the temperature of magnetorheological fluid and silicone oil continues to rise, the elongation of shape memory alloy spring is limited, thereby outputting a clamping force, causing the bearing to press against the magnetic friction ring to produce a friction braking torque. The higher the temperature, the greater the friction torque transmitted, which can further compensate for the torque lost due to the decrease in magnetorheological effect, thereby further ensuring the reliability and stability of braking. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention.

[0020] Figure 2 for Figure 1 Enlarged view of part A in the figure.

[0021] Figure 3 Schematic diagram of the connection structure between two adjacent bearings and the rubber sheet.

[0022] In the figure: 1-brake shaft, 2-base, 3-left end cover, 4-brake cylinder, 5-right end cover, 6-brake segment, 7-excitation coil, 8-magnetic isolation friction ring, 9-friction top block, 10-guide column, 11-shape memory alloy spring, 12-bearing bush, 13-rubber sheet, 141-cylindrical shell, 142-filter membrane, 15-magnetorheological fluid, 16-silicon oil, 17-guide rod, 18-blocking ring, 19-injection plug. DETAILED DESCRIPTION

[0023] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0024] Example: See Figures 1 to 3A hot extrusion volume percentage bearing type magnetorheological fluid brake comprises a brake housing, a brake shaft 1 and a base 2. The brake housing comprises a left end cover 3, a brake cylinder 4 and a right end cover 5 which are connected in sequence, and the base 2 is fixedly connected to the middle of the brake cylinder 4; the base 2 is used to be fixedly connected to the ground, etc., to provide support for the brake. The right end of the brake shaft 1 passes through the left end cover 3 and then extends into the brake housing, and is rotatably connected to the left end cover 3 and the right end cover 5 through bearings, wherein the bearing adopts a sealed bearing to prevent the liquid in the brake housing from leaking; in order to further improve the anti-leakage effect, a felt ring is also provided between the brake shaft 1 and the left end cover 3, and the felt ring is located outside the sealed bearing. The part of the brake shaft 1 located in the brake housing is enlarged to form a brake segment 6, and there is a gap between the side wall of the brake segment 6 and the inner wall of the brake housing. On the inner side of the brake cylinder 4, near both ends, there are coil grooves around it, and an excitation coil 7 is provided in each of the two coil grooves. On the inner side of the brake cylinder 4, a magnetic isolation friction ring 8 is provided at the position corresponding to the two coil grooves, wherein the inner surface of the magnetic isolation friction ring 8 is a friction surface. The magnetic isolation friction ring 8 is fixedly connected to the brake cylinder 4, and the excitation coil 7 is enclosed in the coil groove; in the actual processing process, the two coil grooves respectively penetrate the two ends of the brake cylinder 4, so as to facilitate the installation of the excitation coil 7 and the magnetic isolation friction ring 8, and after the left end cover 3 and the right end cover 5 are connected to the brake cylinder 4, a complete coil groove is formed; in this way, processing and assembly are more convenient.

[0025] Near both ends of the braking segment 6, corresponding to the positions of the two magnetic friction rings 8, a number of receiving grooves are provided respectively, and the positions of the receiving grooves near the two ends of the braking segment 6 correspond, that is, the (axial centerline) connecting line of the two receiving grooves at the corresponding positions is parallel to the axial centerline of the braking end. Among them, the receiving grooves are evenly distributed around the braking segment 6, and the depth direction of the receiving grooves is consistent with the radial direction of the braking segment 6. A friction top block 9, a guide column 10 and a shape memory alloy spring 11 are provided in the receiving groove. The guide column 10 is arranged along the radial direction of the braking segment 6, and its inner end is fixedly connected to the bottom of the groove of the receiving groove. The outer side surface of the friction top block 9 is a friction surface, and the friction top block 9 is connected to the outer end of the guide column 10 by sliding fit, and a first sealing ring is provided between its side wall and the side wall of the receiving groove, and the first sealing ring is fixedly connected to the friction top block 9. In specific implementation, a guide rod 17 is provided on the inner side of the friction top block 9, and a guide hole is provided on the guide column 10 along its axial direction. The guide rod 17 extends into the guide hole and is connected with the guide column 10 in a sliding manner; in this way, the friction top block 9 can be effectively guided, thereby ensuring that the moving direction of the friction top block 9 is always consistent with the radial direction of the braking segment 6. The shape memory alloy spring 11 is located between the friction top block 9 and the bottom of the accommodating groove, and is sleeved on the guide column 10, and its two ends are fixedly connected to the friction top block 9 and the bottom of the accommodating groove respectively. In the initial state, under the action of the shape memory alloy spring 11, the friction top block 9 is located in the accommodating groove.

[0026] On the outside of the braking section 6 of the brake shaft 1, several bearing bushes 12 with arc-shaped cross sections are arranged around it. Both sides of the bearing bushes 12 are friction surfaces. In the initial state, the bearing bushes 12 fit with the braking section 6, and there is a gap between the outer wall and the inner wall of the magnetic isolation friction ring 8, and the adjacent sides of two adjacent bearing bushes 12 fit together to form a sleeve; when the bearing bushes 12 move outward, their outer walls can fit with the inner wall of the magnetic isolation friction ring 8, so that the contact area between the bearing bushes 12 and the magnetic isolation friction ring 8 is larger, so that a larger friction braking torque can be transmitted. During the processing, a retaining ring 18 is respectively provided at both ends of the braking section 6. The inner side of the retaining ring 18 is fixedly connected to the braking section 6 by interference fit, and the outer side extends to form a misalignment with the magnetic isolation friction ring 8. The two ends of the bearing bush 12 fit with the two retaining rings 18 respectively, and can move along the radial direction of the braking section 6 close to the retaining rings 18. In this way, both the two ends of the bearing shell 12 can be limited, and the moving direction of the bearing shell 12 can be limited, so as to ensure the stability of the bearing shell 12 during operation. A rubber sheet 13 is provided on the outer side of the joint of two adjacent bearing shells 12, and the two adjacent bearing shells 12 are connected by the rubber sheet 13; in specific implementation, after the rubber sheet 13 is attached to the two adjacent bearing shells 12 by adhesive, its two ends extend to the two ends of the bearing shell 12 respectively, and are fixedly connected to the two adjacent bearing shells 12 by screws. Under the action of the rubber sheet 13, the two adjacent bearing shells 12 are tightly attached together and attached to the brake segment 6, and the gap between the two adjacent bearing shells 12 is closed by the rubber sheet 13. Among them, the number of the bearing shells 12 is consistent with the number of the receiving grooves at one end of the brake segment 6, and the two ends of the bearing shell 12 extend to the outer side of the two receiving grooves at the corresponding positions respectively, and the middle of the arc direction (section) thereof is directly opposite to the friction top block 9 in the receiving groove.

[0027] An axial hole is provided at the right end of the brake shaft 1, and the inner end of the axial hole extends to the middle of the brake segment 6, and the outer end is closed by a plug. In the middle of the brake segment 6, several oil guide holes are provided around it, and the oil guide holes are arranged along the radial direction of the brake segment 6, and the positions of the oil guide holes correspond to the positions of the receiving grooves at one end of the brake segment 6, that is, the axis of the oil guide hole is parallel to the axis of the two receiving grooves at the corresponding positions. The inner end of the oil guide hole extends to communicate with the axial hole, and the middle part is connected with the two receiving grooves at the corresponding positions through the connecting hole. A filter is provided at the outer end of the oil guide hole, and there is a gap between the filter and the inner wall of the brake housing. A through hole is provided on the bearing bush 12 at the position corresponding to the filter, and the bearing bush 12 is sleeved on the filter through the through hole and is connected with the filter in a sliding fit. In specific implementation, the filter includes a cylindrical shell 141 and a filter membrane 142, and the filter membrane 142 can only allow the base liquid in the magnetorheological fluid 15 to pass through. One end of the cylindrical shell 141 is fixedly connected to the brake segment 6 and communicated with the oil guide hole, and the other end extends to form a misalignment with the magnetic isolation friction ring 8, and has a gap with the inner wall of the brake cylinder 4. The bearing bush 12 is connected to the cylindrical shell 141 in a sliding fit, wherein a second sealing ring is provided between the bearing bush 12 and the cylindrical shell 141, and the second sealing ring is fixedly connected to the bearing bush 12. The filter adopts the above solution, and the structure is simpler, the processing is more convenient, and it is easier to assemble.

[0028] The gap between the outer wall of the bearing bush 12 and the inner wall of the brake housing is filled with magnetorheological fluid 15, and the shaft hole, oil guide hole, connecting hole and accommodating groove are filled with silicone oil 16. A liquid injection hole is provided on the brake cylinder 4, and the liquid injection hole is connected to the inside of the brake housing. A liquid injection plug 19 is provided in the liquid injection hole to facilitate the filling and replacement of the magnetorheological fluid 15.

[0029] During work:

[0030] During the assembly process, the magnetorheological fluid 15 is injected into the working gap (the gap between the outer wall of the bearing bush 12 and the inner wall of the brake housing), wherein the radial length of the working gap is 2 mm, the base fluid of the magnetorheological fluid 15 is silicone oil 16, and the volume percentage of magnetic particles is 25%; at the same time, the silicone oil 16 is injected into the shaft hole, the oil guide hole, the connecting hole and the containing groove.

[0031] 2. When the brake shaft 1 rotates and the excitation coil 7 is not energized, the magnetic particles in the magnetorheological fluid 15 gather on the inner wall of the outer cylinder under the action of centrifugal force, and the brake shaft 1 is only in contact with the base fluid (silicone oil 16) in the magnetorheological fluid 15. The bearing bush 12 is attached to the brake end under the pulling force of the rubber sheet 13, so the pressure on the magnetorheological fluid 15 is extremely small, and the viscous torque generated by the base fluid in the magnetorheological fluid 15 is extremely small, and almost no braking effect is produced.

[0032] 3. After the excitation coil 7 is energized, the excitation coil 7 generates a magnetic flux, which passes through the working gap of the magnetorheological fluid 15. The magnetic particles in the magnetorheological fluid 15 are arranged into a chain structure along the direction of the magnetic flux. The shear stress of the chain structure generates a braking torque to brake the braking section 6 of the brake shaft 1.

[0033] 4. During continuous braking, the working temperature of the magnetorheological fluid 15 in the device gradually rises. When it reaches a certain temperature (such as 70°C), the performance of the magnetorheological fluid 15 begins to decline, and the braking performance also declines. The decline becomes more significant as the temperature rises. At the same time, the heat generated by the magnetorheological fluid 15 is conducted through the silicone oil 16. Since the shape memory alloy spring 11 is immersed in the silicone oil 16, the heat generated by the magnetorheological fluid 15 is quickly conducted to the shape memory alloy spring 11, so that the shape memory alloy spring 11 pushes the friction top block 9 to move outward under the action of the thermal effect, and then pushes the bearing 12 to move outward. The movement of the bearing 12 squeezes the magnetorheological fluid 15, so that part of the base fluid (silicone oil 16) in the working gap passes through the filter membrane 142 and flows into the oil storage chamber through the oil guide hole; together with the silicone oil 16, the friction top block 9 is additionally pushed, thereby further pushing the bearing 12 to squeeze the magnetorheological fluid 15; at this time, the working gap of the magnetorheological fluid 15 is 1mm, and the volume percentage of the magnetic particles becomes 49.6%. As the working gap becomes smaller, the volume percentage of the magnetic particles increases, the magnetic permeability increases, the shear stress of the magnetorheological fluid 15 increases by 25.4%, and the braking torque generated by the magnetorheological fluid 15 also increases, thereby compensating for the influence of the temperature increase on the magnetorheological fluid 15.

[0034] 5. As the work continues, the heat generated by the magnetorheological fluid 15 continues to increase, and the length of the shape memory alloy spring 11 continues to extend, thereby pushing the bearing 12 to contact the inner wall of the magnetic isolation friction ring 8 through the friction top block 9, and generating pressure to generate friction torque, thereby compensating for the braking torque loss caused by the performance degradation of the magnetorheological fluid 15, and increasing the output braking torque, thereby effectively improving the reliability and stability of the braking torque output by the magnetorheological fluid 15 brake.

[0035] In this scheme, the shear yield stress can be increased by increasing the volume fraction of magnetic particles in the magnetorheological fluid 15, but the volume fraction of magnetic particles needs to be within a reasonable range. If the volume fraction is too low, a larger magnetic field strength is required to achieve the required shear yield stress; if the volume fraction is too high, the magnetic particles of the magnetorheological fluid 15 have formed a complex network structure in the zero magnetic field, which is manifested as a large zero-field viscosity on a macro scale. The magnetorheological effect is not obvious under the action of an external magnetic field, and the transmission device cannot play a dynamic adjustment role. In addition, if the volume fraction is too large, serious sedimentation and hardening are prone to occur, affecting the working efficiency of the magnetorheological transmission device. The defects of the fixed volume fraction magnetorheological fluid 15 are cleverly solved by increasing the volume fraction of magnetic particles in the magnetorheological fluid 15 by extruding the bearing 12. The volume fraction of the magnetorheological fluid 15 is automatically and dynamically adjusted by the shape memory alloy, so that when not braking, the zero-field viscosity is small to reduce additional energy consumption. When braking and the braking torque demand is large, the volume fraction of magnetic particles can be increased to improve the braking torque of the brake. When braking is ended, the base fluid is sucked back into the working gap of the magnetorheological fluid 15 , and the volume fraction of the magnetorheological fluid 15 is reduced to the initial state, thereby enhancing the anti-sedimentation property of the magnetorheological fluid 15 .

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A hot extruded volume percentage bearing type magnetorheological fluid brake, comprising a brake housing, a brake shaft and a base; the brake housing comprises a left end cover, a brake cylinder and a right end cover which are connected in sequence, and the base is fixedly connected to the middle of the brake cylinder; the right end of the brake shaft passes through the left end cover and then extends into the brake housing, and is rotatably connected to the left end cover and the right end cover through a bearing, the part of the brake shaft located in the brake housing is expanded to form a brake section, and there is a gap between the side wall of the brake section and the inner wall of the brake housing; on the inner side of the brake cylinder, near both ends, there are respectively provided with coil grooves which surround it, and an excitation coil is respectively provided in the two coil grooves; the characteristics are: On the inner side of the brake cylinder, a magnetic isolation friction ring is respectively provided at the position corresponding to the two coil slots, and the magnetic isolation friction ring is fixedly connected to the brake cylinder and seals the excitation coil in the coil slot; Near both ends of the braking section, corresponding to the positions of the two magnetic isolation friction rings, a number of receiving grooves are respectively provided, and the positions of the receiving grooves near the two ends of the braking section correspond, wherein the receiving grooves are evenly distributed around the braking section, and the depth direction of the receiving grooves is consistent with the radial direction of the braking section; a friction top block, a guide column and a shape memory alloy spring are provided in the receiving groove; the guide column is arranged along the radial direction of the braking section, and its inner end is fixedly connected to the groove bottom of the receiving groove; the friction top block is connected to the outer end of the guide column by sliding fit, and a first sealing ring is provided between its side wall and the side wall of the receiving groove; the shape memory alloy spring is located between the friction top block and the groove bottom of the receiving groove, and is sleeved on the guide column, and its two ends are fixedly connected to the friction top block and the groove bottom of the receiving groove, respectively. In the initial state, under the action of the shape memory alloy spring, the friction top block is located in the receiving groove; On the outside of the braking section of the brake shaft, several arc-shaped bearing shells are arranged around it. In the initial state, the bearing shell is fitted with the braking section, and there is a gap between its outer wall and the magnetic isolation friction ring, and the adjacent two sides of two adjacent bearing shells are fitted together to form a sleeve; a rubber sheet is provided on the outside of the fitting part of two adjacent bearing shells, and the two adjacent bearing shells are connected by the rubber sheet; wherein, the number of the bearing shells is consistent with the number of the receiving grooves at one end of the braking section, and the two ends of the bearing shells extend to the outside of the two receiving grooves at the corresponding positions respectively, and the middle part of the arc direction is directly opposite to the friction top block in the receiving groove; a retaining ring is provided at each end of the braking section, the inner side of the retaining ring is fixedly connected to the braking section, and the outer side extends to form an offset with the magnetic isolation friction ring; the two ends of the bearing shell are fitted with the two retaining rings respectively, and can move closely against the retaining rings along the radial direction of the braking section; An axial hole is provided at the right end of the brake shaft, the inner end of the axial hole extends to the middle of the brake segment, and the outer end is closed by a plug; in the middle of the brake segment, a plurality of oil guide holes are provided around it, the oil guide holes are arranged along the radial direction of the brake segment, and the positions of the oil guide holes correspond to the positions of the receiving grooves at one end of the brake segment; the inner end of the oil guide hole extends to communicate with the axial hole, and the middle part thereof is connected with the two receiving grooves at corresponding positions through a connecting hole; a filter is provided at the outer end of the oil guide hole, and there is a gap between the filter and the inner wall of the brake housing ; A through hole is provided on the bearing shell at the position corresponding to the filter, and the bearing shell is sleeved on the filter through the through hole and is connected with the filter in a sliding manner; the filter comprises a cylindrical shell and a filter membrane, one end of the cylindrical shell is fixedly connected with the brake section and communicated with the oil guide hole, and the other end extends to form a misalignment with the magnetic isolation friction ring, and has a gap with the inner wall of the brake cylinder; the bearing shell is connected with the cylindrical shell in a sliding manner, wherein a second sealing ring is provided between the bearing shell and the cylindrical shell, and the second sealing ring is fixedly connected with the bearing shell; The gap between the outer wall of the bearing bush and the inner wall of the brake housing is filled with magnetorheological fluid, and the shaft hole, the oil guide hole, the connecting hole and the containing groove are filled with silicone oil.

2. The hot extruded volume percentage bearing type magnetorheological fluid brake according to claim 1, characterized in that: A guide rod is arranged on the inner side of the friction top block, and a guide hole is arranged on the guide column along its axial direction. The guide rod extends into the guide hole and is connected with the guide column in a sliding fit.

3. The hot extruded volume percentage bearing type magnetorheological fluid brake according to claim 1, characterized in that: The brake cylinder is provided with a liquid injection hole which is communicated with the inside of the brake housing, and a liquid injection screw plug is matched in the liquid injection hole.

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