Magnetorheological fluid brake capable of achieving repeated extrusion

Abstract

The invention provides a repeated extrusion magnetorheological fluid brake which comprises a shell, two brake shafts, three brake discs, two driven discs, a first magnet exciting coil, magnetorheological fluid and a flow adjusting assembly, and the brake shafts are rotationally connected to the shell; the three brake discs are arranged in the shell, the two brake discs located on the outermost side are fixedly connected with the two brake shafts respectively, a space defined by every two adjacent brake discs and the shell define an extrusion cavity, and the two extrusion cavities are communicated through a connecting channel arranged in the shell; the two driven discs are respectively arranged in the two extrusion cavities in a sliding manner; the first magnet exciting coil is fixed in the shell; the magnetorheological fluid is arranged in the shell to flow; the flow adjusting assembly comprises a flow adjusting valve and a memory alloy spring, the flow adjusting valve is arranged in the connecting channel in a sliding mode, and a flow opening allowing the magnetorheological fluid to pass through is formed between the flow adjusting valve and the connecting channel; and the memory alloy spring is arranged at one end of the flow regulating valve. Attenuation of braking torque caused by rising of the temperature of magnetorheological fluid can be avoided.

Description

Technical Field

[0001] The present invention relates to a magnetorheological brake, and more particularly to a magnetorheological brake with a repeated extrusion mode. Background Art

[0002] With the development of society, various new materials with different characteristics are emerging continuously. Among them, magnetorheological fluid has shown objective application prospects and values due to its unique rheological characteristics and is receiving continuous attention from the research community. Magnetorheological fluid has good fluidity. After applying an external magnetic field, the magnetorheological fluid can chain within an extremely short time, showing solid characteristics, thus generating a very high yield stress. Moreover, its solid characteristics can be adjusted by the intensity of the applied external magnetic field. After the magnetic field is removed, the magnetorheological fluid can immediately resume its fluidity. Traditional magnetorheological brakes mainly use a shear mode to achieve braking during braking. The single braking form results in a small braking torque for the magnetorheological brake. Most existing magnetorheological brakes increase the braking area of the brake disc to increase the braking torque, leading to an increase in the overall volume of the magnetorheological brake and making it difficult to meet the braking requirements of current miniaturized devices. Chinese patent application with publication number CN113954807A discloses a radially extruded magnetorheological braking device, which designs a horizontal propulsion mechanism. While the magnetorheological fluid starts to solidify, the servo motor increases the torque through a reducer, and then drives the feed of the moving sleeve through a slide rail. The moving sleeve pushes the inclined surface structure to press down the pressurizing column, and then the disc fixing ring applies inward pressure to complete the pressurization of the moving and static discs. With the design of the inclined surfaces of the disc-shaped moving disc and the trapezoidal static disc, the gap between the moving disc and the static disc is reduced, generating radial and axial extrusion on the solidified magnetorheological fluid, realizing the friction between the moving and static discs, increasing the braking force, and thus achieving the effect of complete braking. However, during the continuous braking process, it will cause the temperature of the magnetorheological fluid to rise, resulting in the attenuation of the braking torque. Summary of the Invention

[0003] The present invention aims to at least solve one of the technical problems raised in the above background art, and provides a magnetorheological brake with a repeated extrusion mode, which can avoid the attenuation of the braking torque caused by the increase in the temperature of the magnetorheological fluid during the continuous braking process.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] A magnetorheological fluid brake with a repeated extrusion mode, comprising:

[0006] A housing;

[0007] Two brake shafts, which are coaxially and oppositely arranged and are rotatably connected to the housing;

[0008] Three brake discs are axially spaced along the brake shaft and arranged inside the housing. The two outermost brake discs are respectively fixedly connected to the two brake shafts. The space formed by enclosing every two adjacent brake discs and the housing forms an extrusion chamber, and the two extrusion chambers are communicated through a connection channel arranged inside the housing;

[0009] Two passive disc plates are respectively slidably arranged in the two extrusion chambers. The passive disc plates are connected to the adjacent two brake discs through connecting pieces so as to reciprocate radially along the brake shaft when the brake discs rotate, and the sliding directions of the two passive disc plates are opposite;

[0010] A first excitation coil is fixed inside the housing and is arranged around the outer peripheral side of the brake disc;

[0011] Magnetorheological fluid is arranged to flow inside the housing; and

[0012] A flow rate regulating assembly includes a flow rate regulating valve and a shape memory alloy spring. The flow rate regulating valve is slidably arranged in the connection channel. A flow rate orifice for the magnetorheological fluid to pass through is formed between the flow rate regulating valve and the end of the connection channel; the shape memory alloy spring is arranged at one end of the flow rate regulating valve; when the temperature of the magnetorheological fluid rises, the shape memory alloy spring is affected by the temperature and drags the flow rate regulating valve to move along the connection channel so as to adjust the size of the flow rate orifice.

[0013] Further, the flow rate regulating assembly further includes a resetting member. The resetting member and the shape memory alloy spring are respectively arranged on opposite sides of the flow rate regulating valve. When the temperature of the magnetorheological fluid decays, the resetting member can drive the flow rate regulating valve to reset.

[0014] Further, the flow rate regulating valve includes a body portion and a convex platform protruding from one end of the body portion. An inclined surface is arranged at the connection between the convex platform and the body portion, and the inclined surface faces the extrusion chamber. A gap for the magnetorheological fluid to pass through is formed between the body portion and the inner wall of the connection channel; the flow rate regulating valve can move along the connection channel between a maximum opening position and a closing position. When the flow rate regulating valve is in the closing position, the convex platform contacts the inner wall of the connection channel to close the connection channel; during the process of the flow rate regulating valve moving from the closing position to the maximum opening position, different-sized flow rate orifices are formed between the inclined surface and the end of the connection channel; the opposite ends of the shape memory alloy spring respectively abut against the body portion and the inner wall of the housing.

[0015] Further, the flow rate regulating valve further includes a guide rod. The guide rod is fixedly connected to the body portion and is slidably connected to the housing to guide the movement of the flow rate regulating valve.

[0016] Further, the connecting piece includes a connecting rod and a slider fixedly sleeved on the connecting rod. The connecting pieces on the two passive disc plates are respectively arranged on opposite sides of the center of the brake disc. The connecting rod is fixedly connected to the adjacent two brake discs. The passive disc plates are provided with sliding holes corresponding to the sliders, and the two sliders are respectively slidably arranged in the sliding holes of the corresponding passive disc plates.

[0017] Further, corresponding to the brake disc, there are three first excitation coils, and the three first excitation coils are respectively arranged around the outer peripheral sides of the three brake discs.

[0018] Further, a second excitation coil is also arranged on the middle brake disc.

[0019] Further, a plurality of centrifugal blades are convexly formed on the end faces of the two outermost brake discs. The centrifugal blades are arranged on the end faces of the corresponding brake discs facing the driven disc, and the plurality of centrifugal blades are arranged at intervals along the circumferential direction of the brake discs.

[0020] Further, grooves are arranged on both opposite end faces of the driven disc.

[0021] Further, a pulling member is also connected to the end of the flow regulating valve away from the shape memory alloy spring.

[0022] Due to the adoption of the above technical solutions, the present invention has the following beneficial effects:

[0023] In the existing magnetorheological fluid brake during continuous braking, the temperature of the magnetorheological fluid rises. When it rises to a certain temperature, the braking torque of the magnetorheological fluid brake decays and the braking performance deteriorates. For the reciprocating extrusion magnetorheological fluid brake of the present invention, when the temperature of the magnetorheological fluid rises to a certain temperature during continuous braking, the heat generated is conducted to the shape memory alloy spring. Under the action of the thermal effect, the shape memory alloy spring pushes the flow regulating valve to move along the connection channel, thereby making the opening of the regulating flow port smaller. Since the opening of the flow port becomes smaller, the resistance of the magnetorheological fluid flowing in the two extrusion cavities becomes larger, and the braking torque generated by the magnetorheological fluid brake also increases, thus compensating for the influence caused by the temperature rise on the magnetorheological fluid brake. In addition, for the magnetorheological fluid brake of the present invention, the brake disc drives the driven disc to perform reciprocating extrusion movements, and the structure is simpler, which is beneficial to the miniaturization of the magnetorheological fluid brake. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a perspective view of the magnetorheological fluid brake according to a preferred embodiment of the present invention;

[0025] Figure 2 is Figure 1 exploded view of;

[0026] Figure 3 is a structural schematic diagram of the cylinder body in the magnetorheological fluid brake according to a preferred embodiment of the present invention;

[0027] Figure 4 is a structural schematic diagram of the brake disc and the driven disc in the magnetorheological fluid brake according to a preferred embodiment of the present invention;

[0028] Figure 5 is Figure 4 exploded view of;

[0029] Figure 6 is the exploded view of the brake disc located at the middle position in the magnetorheological fluid brake of the preferred embodiment of the present invention;

[0030] Figure 7 is Figure 1 top view of;

[0031] Figure 8 is Figure 7 sectional view along line A - A;

[0032] Figure 9 is Figure 8 enlarged view at I;

[0033] Figure 10 is Figure 9 enlarged view at the flow rate regulating component, with its flow rate regulating valve in the closed position;

[0034] Figure 11 is Figure 10 structural schematic diagram when the flow rate regulating valve is in the maximum open position;

[0035] Figure 12 is the structural diagram of the flow rate regulating valve in the magnetorheological fluid brake of the preferred embodiment of the present invention;

[0036] Figure 13 is Figure 7 sectional view along line B - B;

[0037] Figure 14 is Figure 1 front view of;

[0038] Figure 15 is Figure 14 sectional view along line C - C;

[0039] Figure 16 is the magnetic induction line distribution diagram of the magnetorheological brake of the preferred embodiment of the present invention;

[0040] Figure 17 is the magnetic induction line distribution diagram of the moving disc in the magnetorheological brake of the preferred embodiment of the present invention;

[0041] Figure 18 is the magnetic induction line distribution diagram of the combination of the moving disc and the passive disc in the magnetorheological brake of the preferred embodiment of the present invention;

[0042] Figure 19 is the magnetic induction line distribution diagram of the passive disc in the magnetorheological brake of the preferred embodiment of the present invention;

[0043] Figure 20Magnetic induction line distribution diagram of the moving disk with an excitation coil in the magnetorheological brake of the preferred embodiment of the invention;

[0044] Figure 21 Magnetic induction line distribution diagram of the magnetorheological fluid in the magnetorheological brake of the preferred embodiment of the invention;

[0045] Description of main component symbols

[0046] 1. Housing; 11. Cylinder body; 111. First installation groove; 112. Second installation groove; 113. Third installation groove; 114. Extrusion groove; 115. First cylinder body; 1151. First flange; 1152. Second flange; 116. Second cylinder body; 1161. Third flange; 1162. Fourth flange; 117. Protrusion; 118. Communication port; 119. Connection channel; 12. End cover; 121. Axial hole; 123. Through hole; 13. Receiving cavity; 15. Guide groove; 2. Brake shaft; 20. Bearing assembly; 21. Bearing part; 22. Bearing cover; 23. Oil seal ring; 3. Brake disk; 31. Centrifugal blade; 32. Disk body; 321. Main body part; 323. Shaft body; 324. Fixed groove; 325. Communication groove; 34. Disk cover; 4. Driven disk plate; 41. Sliding hole; 43. Groove; 5. First excitation coil; 6. Extrusion cavity; 7. Flow rate adjustment component; 71. Flow rate regulating valve; 711. Body part; 713. Boss; 715. Inclined surface; 716. Guide rod; 73. Shape memory alloy spring; 75. Flow port; 76. Reset part; 77. Pulling part; 8. Second excitation coil; 9. Connecting part; 91. Connecting rod; 93. Slide block. Detailed implementation manners

[0047] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0048] It should be noted that when a component is referred to as being "fixed to" another component, it can be directly on the other component or there may also be an intermediate component. When a component is considered to be "connected" to another component, it can be directly connected to the other component or there may be an intermediate component at the same time. When a component is considered to be "disposed on" another component, it can be directly disposed on the other component or there may be an intermediate component at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for the purpose of illustration.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0050] Please refer to Figure 1 、 Figure 2 、 Figure 7 and Figure 8 , a reciprocating extrusion magnetorheological fluid brake provided by a preferred embodiment of the present invention includes a housing 1, a brake shaft 2, a brake disc 3, a passive disc 4, a first excitation coil 5, a magnetorheological fluid (not shown in the figure), and a flow rate adjustment component 7.

[0051] In this embodiment, the housing 1 includes a cylinder 11 and two end caps 12 respectively fixed to opposite ends of the cylinder 11, and a receiving cavity 13 is formed between the cylinder 11 and the two end caps 12. Please refer to Figure 9 together, on the inner wall of the cylinder 11, a first installation groove 111, a second installation groove 112, and a third installation groove 113 are recessed at intervals along the axial direction of the cylinder 11, and an extrusion groove 114 is formed between the first installation groove 111 and the second installation groove 112 and between the second installation groove 112 and the third installation groove 113. Please refer to Figure 3 together. Specifically, in this embodiment, the cylinder 11 includes a first cylinder 115 and a second cylinder 116 arranged in sequence along the axial direction of the cylinder 11 and fixedly connected to each other. Among them, on the inner wall of the first cylinder 115, a first flange 1151 and a second flange 1152 are convexly provided at intervals along the axial direction of the cylinder 11, and on the inner wall of the second cylinder 116, a third flange 1161 and a fourth flange 1162 are convexly provided at intervals along the axial direction of the cylinder 11. A first installation groove 111 is formed by enclosing between the first flange 1151, the first cylinder 115, and one of the end caps 12, a second installation groove 112 is formed by enclosing between the second flange 1152, the third flange 1161, and the second cylinder 116, a third installation groove 113 is formed by enclosing between the fourth flange 1162, the second cylinder 116, and the other end cap 12, an extrusion groove 114 is formed by enclosing between the first flange 1151, the second flange 1152, and the first cylinder 115, and another extrusion groove 114 is formed by enclosing between the third flange 1161, the fourth flange 1162, and the second cylinder 116. This structural arrangement can facilitate the manufacture of the housing 1 and the assembly of each component more conveniently.

[0052] In this embodiment, two pairs of protrusions 117 are further convexly provided on the inner walls of the first cylinder 115 and the second cylinder 116. The two pairs of protrusions 117 of the first cylinder 115 are located in the corresponding extrusion grooves 114 and are arranged oppositely. The two pairs of protrusions 117 of the second cylinder 116 are located in the corresponding extrusion grooves 114 and are arranged oppositely. Each pair of protrusions 117 is arranged at intervals to form a communication port 118. A connection channel 119 communicating the two extrusion grooves 114 is further formed on the cylinder 11 of the housing 1. In this embodiment, the number of the connection channels 119 is two. The two connection channels 119 are arranged oppositely and are both provided between the corresponding two pairs of protrusions 117. The connection channel 119 extends from the first cylinder 115 to the second cylinder 116 along the axial direction of the cylinder 11. The opposite ends of the connection channel 119 communicate with the two extrusion grooves 114 respectively.

[0053] The number of the brake shafts 2 is two. The two brake shafts 2 are arranged coaxially and oppositely and are both rotatably connected to the housing 1. In this embodiment, the two brake shafts 2 are respectively rotatably connected to the two end caps 12. Specifically, shaft holes 121 corresponding to the brake shafts 2 are provided on the end caps 12 of the housing 1. One end of the brake shaft 2 is rotatably connected to the shaft hole 121 through a bearing assembly 20. An oil seal ring 23 sleeved on the brake shaft 2 is further installed in the shaft hole 121. In this embodiment, the bearing assembly 20 includes a bearing part 21 and a bearing cover 22. The bearing part 21 is sleeved on the brake shaft 2, so that the brake shaft 2 is rotatably connected to the end cap 12 through the bearing part 21. The bearing cover 22 is sleeved on the brake shaft 2 and covers the outside of the bearing part 21, so as to protect the bearing part 21 and prevent foreign matters from entering the bearing part 21 and affecting the rotation of the brake shaft 2. The structure of the bearing part 21 belongs to the prior art. For example, ball bearings and roller bearings in the prior art can be adopted. The setting of the oil seal ring 23 can further improve the sealing performance of the housing 1. The structure of the oil seal ring 23 belongs to the prior art. For the sake of brevity, it will not be elaborated here.

[0054] Please refer to Figure 4 、 Figure 5 and Figure 10 simultaneously. The number of the brake discs 3 is three. The three brake discs 3 are arranged at intervals along the axial direction of the brake shaft 2 in the receiving cavity 13 of the housing 1. The two brake discs 3 located on the outermost sides are respectively fixedly connected to the two brake shafts 2. A space formed between every two adjacent brake discs 3 and the housing 1 encloses an extrusion cavity 6. The two extrusion cavities 6 are communicated through the connection channel 119 provided in the housing 1.

[0055] In this embodiment, the two outermost brake discs 3 can be fixedly connected to the corresponding brake shafts 2 through connecting members 9 such as screws. A gap for the flow of magnetorheological fluid is formed between the peripheral wall of the brake disc 3 and the inner wall of the housing 1. A plurality of centrifugal vanes 31 protrude from one end face of at least one brake disc 3, and the plurality of centrifugal vanes 31 are arranged at intervals along the circumferential direction of the brake disc 3. In this embodiment, a plurality of centrifugal vanes 31 protrude from the end faces of the two outermost brake discs 3 facing the extrusion chamber 6. In addition, a second excitation coil 8 is also provided on the brake disc 3 located in the middle. Specifically, please refer to Figure 6 , the brake disc 3 located in the middle includes a disc body 32 and a disc cover 34. The disc body 32 includes a main body portion 321 and a shaft body 323 protruding from a substantially central position of one end face of the main body portion 321. A plurality of sets of fixing grooves 324 are arranged at intervals along the circumferential direction of the disc body 32 on the end face of the main body portion 321 where the shaft body 323 is provided. A plurality of fixing grooves 324 in each set are arranged at intervals in a direction away from the shaft body 323, and the cross-sections of the plurality of fixing grooves 324 in each set gradually increase in a direction away from the shaft body 323, and adjacent two fixing grooves 324 are connected through a communication groove 325. In this embodiment, each set of fixing grooves 324 includes two fixing grooves 324; both of the two fixing grooves 324 are annular, and the second excitation coil 8 is installed in the fixing grooves 324. The arrangement of the plurality of sets of fixing grooves 324 can provide more space for the second excitation coils 8 on the disc body 32, and the arrangement of the communication grooves 325 can conveniently accommodate the leads of the second excitation coils 8 for connecting to the power supply. The disc cover 34 is fixedly sleeved on the shaft body 323 and covers the openings of the plurality of sets of fixing grooves 324 of the disc body 32 to seal the fixing grooves 324, so that the second excitation coils 8 are embedded in the brake disc 3 located in the middle. Please refer to Figures 13 to 15 , each adjacent two brake discs 3 and the housing 1 enclose an extrusion chamber 6. Specifically, in this embodiment, the space formed by adjacent two brake discs 3 and a corresponding extrusion groove 114 enclose an extrusion chamber 6. The two extrusion chambers 6 are connected through a connection channel 119 provided in the housing 1. In addition, in this embodiment, the two extrusion chambers 6 are also connected through a communication port 118.

[0056] The number of the driven discs 4 is two. The two driven discs 4 are respectively slidably arranged in the two extrusion cavities 6. The driven discs 4 are connected to the adjacent two brake discs 3 through the connecting members 9, so as to reciprocate radially along the brake shaft 2 when the brake discs 3 rotate, and the sliding directions of the two driven discs 4 are opposite. In this embodiment, the connecting member 9 includes a connecting rod 91 and a slider 93 fixedly sleeved on the connecting rod 91. The connecting members 9 on the two driven discs 4 are respectively arranged on the opposite sides of the center of the brake disc 3. The connecting rod 91 is fixedly connected to the adjacent two brake discs 3. The driven disc 4 is provided with a sliding hole 41 corresponding to the slider 93, and the two sliders 93 are respectively slidably arranged in the sliding holes 41 of the corresponding driven discs 4. When in use, through the cooperation of the connecting rod 91, the slider 93 and the sliding hole 41, the rotational motion of the brake disc 3 is converted into the linear reciprocating motion of the slider 93 along the radial direction of the brake disc 3. In addition, in this embodiment, grooves 43 are provided on both opposite end faces of the driven disc 4. Specifically, two groups of grooves 43 are provided on each end face of the driven disc 4. The two groups of grooves 43 are respectively arranged on the opposite sides of the sliding hole 41. A plurality of grooves 43 in each group are arranged at intervals in the direction away from the sliding hole 41. The grooves 43 are in an arc structure, and the protruding directions of the two groups of grooves 43 are opposite.

[0057] The first excitation coil 5 is fixed in the housing 1 and is arranged around the outer peripheral side of the brake disc 3. In this embodiment, the number of the first excitation coils 5 corresponding to the brake disc 3 is three. The three first excitation coils 5 are respectively arranged around the outer peripheral sides of the three brake discs 3, and the three first excitation coils 5 are respectively fixed in the first installation groove 111, the second installation groove 112 and the third installation groove 113.

[0058] The magnetorheological fluid is arranged to flow in the housing 1. In this embodiment, the magnetorheological fluid can flow in the gaps formed by the inner wall of the housing 1, the brake disc 3, the driven disc body 32, as well as the extrusion groove 114, the connecting channel 119 and the communication port 118.

[0059] Please refer to Figure 11 as well. The flow rate regulating assembly 7 includes a flow rate regulating valve 71 and a shape memory alloy spring 73. The flow rate regulating valve 71 is slidably installed in the connecting channel 119. A flow rate port 75 for the magnetorheological fluid to pass through is formed between the flow rate regulating valve 71 and the connecting channel 119. The shape memory alloy spring 73 is arranged at one end of the flow rate regulating valve 71. When the temperature of the magnetorheological fluid rises with the increase of the number of braking times, the shape memory alloy spring 73 is affected by the temperature and drags the flow rate regulating valve 71 to move along the connecting channel 119 so as to adjust the size of the flow rate port 75.

[0060] Please refer to Figure 12, in this embodiment, the flow regulating valve 71 includes a body portion 711 and a boss 713 protruding from one end of the body portion 711. The body portion 711 is slidably disposed in the connection passage 119 and forms a gap for the magnetorheological fluid to pass through with the inner wall of the connection passage 119. An inclined surface 715 is provided at the connection between the boss 713 and the body portion 711. The inclined surface 715 faces the extrusion chamber 6, and the inclined surface 715 is inclined gradually in the direction away from the boss 713 and towards the body portion 711. The flow regulating valve 71 can move along the connection passage 119 between a maximum open position ( Figure 11 ) and a closed position ( Figure 10 ): When the flow regulating valve 71 is in the closed position, the boss 713 contacts the inner wall of the connection passage 119 to close the connection passage 119; when the flow regulating valve 71 is in the maximum open position, the boss 713 disengages from the connection passage 119, so that the opening of the flow port 75 is maximized; during the process of the flow regulating valve 71 moving from the closed position to the maximum open position, different-sized flow ports 75 are formed between the inclined surface 715 and the end of the connection passage 119.

[0061] In this embodiment, the slidable direction of the flow regulating valve 71 is parallel to the axial direction of the brake shaft 2. A guide rod 716 is also fixedly connected to the body portion 711. The guide rod 716 is slidably connected to the housing 1 to guide the movement of the flow regulating valve 71. Specifically, one end of the guide rod 716 is fixed to the end of the body portion 711 away from the shape memory alloy spring 73. A guide groove 15 is provided on the first cylinder 115 of the housing 1 and one of its end covers 12. One end of the guide groove 15 communicates with the extrusion chamber 6, and the other end of the guide groove 15 penetrates the outer surface of the end cover 12. The guide rod 716 is slidably disposed in the guide groove 15. To further improve the sealing performance of the housing 1, an oil seal ring 23 can also be provided between the peripheral wall of the guide rod 716 and the first cylinder 115 of the housing 1.

[0062] In this embodiment, the opposite ends of the shape memory alloy spring 73 respectively abut against the body portion 711 and the housing 1. Specifically, the opposite ends of the shape memory alloy spring 73 respectively abut against the body portion 711 and the wall of one of the extrusion grooves 114. The telescopic direction of the shape memory alloy spring 73 is parallel to the axial direction of the brake shaft 2. The flow regulating assembly 7 further includes a reset member 76. The reset member 76 and the shape memory alloy spring 73 are respectively disposed on opposite sides of the flow regulating valve 71. When the temperature of the magnetorheological fluid decays, the reset member 76 can drive the flow regulating valve 71 to reset. In this embodiment, the reset member 76 is a reset spring. The reset member 76 is sleeved on the guide rod 716, and the opposite ends of the reset member 76 respectively abut against the body portion 711 and the inner wall of the cylinder 11 (in this embodiment, the inner wall of the first cylinder 115). The telescopic direction of the reset member 76 is parallel to the axial direction of the brake shaft 2.

[0063] In this embodiment, the flow rate regulating assembly 7 further includes a pulling member 77. The pulling member 77 is connected to one end of the flow rate regulating valve 71 away from the shape memory alloy spring 73. The flow rate regulating valve 71 can be pulled by the pulling member 77 to move between the maximum opening position and the closing position, thereby adjusting the opening size of the flow port 75. The pulling member 77 can be made of a steel wire. One end of the pulling member 77 is fixedly connected to the guide rod 716 of the flow rate regulating valve 71, and the other end of the pulling member 77 can extend outside the housing 1 for convenient pulling. Specifically, a through hole 123 is formed in the end cover 12 away from the shape memory alloy spring 73 corresponding to the pulling member 77, and the pulling member 77 passes through the housing 1 from the corresponding through hole 123.

[0064] During use, the brake shaft 2 of the magnetorheological brake is connected to the equipment to be braked, such as an automobile. When the first excitation coil 5 and the second excitation coil 8 are de-energized, the brake shaft 2 rotates together with the equipment to be braked, and drives the three brake discs 3 to rotate together. The rotation of the brake discs 3 drives the passive disc 4 to reciprocate in a direction perpendicular to the brake shaft 2. At this time, the magnetorheological brake does not perform braking, the temperature of the magnetorheological fluid does not increase, and the flow rate regulating valve 71 is in the maximum opening position, so that the opening of the flow port 75 connecting the two extrusion chambers 6 is the largest.

[0065] When it is necessary to brake the equipment, the first excitation coil 5 can be energized alone or the first excitation coil 5 and the second excitation coil 8 can be energized simultaneously according to the required braking force, and an adjustable magnetic field is generated in the working gap filled with the magnetorheological fluid ( Figures 16 - 21) When the excitation coil is energized, the adjustable magnetic field generated acts on the magnetorheological fluid, causing the particles to form a chain-like structure, thereby increasing its viscosity, and thus generating a certain braking force on the rotating brake disc 3. By adjusting the magnitude of the current passing through the first excitation coil 5 or the second excitation coil 8, different magnitudes of magnetic fields are generated to change the viscosity of the magnetorheological fluid. The morphology of the magnetorheological fluid changes and transforms into a quasi-solid state, and the generated torque is transmitted to the brake shaft 2, thereby obtaining the required magnitude of braking force. At the same time, the rotation of the brake disc 3 drives the passive disc 4 to reciprocate repeatedly in a direction perpendicular to the brake shaft 2, squeezing the magnetorheological fluid, thereby braking the rotating brake shaft 2 and further increasing the braking torque. During the braking process, when the temperature of the magnetorheological fluid increases with the increase in the number of braking times, resulting in a decay of the braking torque, the shape memory alloy spring 73 of the flow rate regulating assembly 7 is affected by the temperature and pushes the flow rate regulating valve 71 to move, thereby adjusting the opening size of the flow port 75, making the opening of the regulating flow port 75 smaller, increasing the resistance of the magnetorheological fluid flowing in the two extrusion chambers 6, and increasing the braking torque generated by the magnetorheological fluid brake, thereby compensating for the impact caused by the temperature increase on the magnetorheological fluid brake. When the temperature of the magnetorheological fluid decays, the shape memory alloy spring 73 returns to its original position. However, in this embodiment, since the flow rate regulating valve 71 only contacts the shape memory alloy spring 73, the flow rate regulating valve 71 cannot move and reset following the shape memory alloy spring 73. To solve this problem, a reset member 76 is provided at one end of the flow rate regulating valve 71 away from the shape memory alloy spring 73. The reset member 76 uses a reset spring, and its thrust does not change with the change in temperature. Therefore, when the shape memory alloy spring 73 is affected by the temperature and pushes the flow rate regulating valve 71 to move, the reset member 76 is compressed, and when the temperature of the magnetorheological fluid decays, the elastic restoring force of the reset member 76 can pull the flow rate regulating valve 71 to reset. When the braking ends, the excitation coil is de-energized, and the magnetorheological fluid returns to the liquid state.

[0066] During the continuous braking process of the existing magnetorheological fluid brake, when the temperature of the magnetorheological fluid rises to a certain temperature (such as 70 °C), the braking torque of the magnetorheological fluid brake decays and the braking performance deteriorates. For the reciprocating extrusion magnetorheological fluid brake of the present invention, when the temperature of the magnetorheological fluid rises to a certain temperature during the continuous braking process, the heat generated is conducted to the shape memory alloy spring 73. Under the action of the thermal effect, the shape memory alloy spring 73 pushes the flow regulating valve 71 to move along the connecting channel 119, so that the opening of the regulating flow port 75 becomes smaller. Since the opening of the flow port 75 becomes smaller, the resistance of the magnetorheological fluid flowing in the two extrusion chambers 6 becomes larger, and the braking torque generated by the magnetorheological fluid brake also increases, thus compensating for the influence of the temperature rise on the magnetorheological fluid brake. In addition, for the magnetorheological fluid brake of the present invention, the brake disc 3 drives the passive disc 4 to perform reciprocating extrusion movement, and the extrusion effect on the magnetorheological fluid is better, which can further increase the braking torque, and the structure is simpler, which is conducive to the miniaturization of the magnetorheological fluid brake.

[0067] During the braking process of the equipment, if an accidental power failure occurs and the excitation coil cannot provide a magnetic field, since the excitation coil cannot provide a magnetic field at this time and cannot solidify the magnetorheological fluid, therefore, no braking torque can be generated on the brake shaft 2, which is likely to pose a safety hazard to the user of the equipment in use. At this time, if it is urgent to stop the rotation of the brake shaft 2, the flow regulating valve 71 can be driven to close the flow port 75 by pulling the pulling member 77 connected to the flow regulating valve 71. The resistance of the magnetorheological fluid flowing in the two extrusion chambers 6 increases, and the generated braking torque is transmitted to the brake disc 3 and the brake shaft 2, so as to achieve the emergency stop braking effect and provide power-off protection for the equipment, improving the safety of equipment use. In addition, during the process of the excitation coil being unable to provide a magnetic field and emergency stop braking, if different braking torques are required, the flow regulating valve 71 can be pulled to different positions by a steel wire to adjust the opening size of the flow port 75, so as to provide different braking torques for the brake shaft 2 and achieve the required braking effect.

[0068] In addition, if the magnetorheological fluid is placed for too long, it will cause the magnetorheological fluid to agglomerate and stratify, affecting the braking performance and unable to best exert its characteristics. To solve this problem, in this embodiment, grooves 43 are formed on the surface of the passive disc 4, and centrifugal blades 31 are provided on the end surface of the brake disc 3 facing the passive disc 4. The grooves 43 formed on the surface of the passive disc 4 and the centrifugal blades 31 provided on the end surface of the brake disc 3 can stir the magnetorheological fluid to prevent the magnetorheological fluid from settling and stratifying. The principle is: only the second excitation coil 8 is energized to make the brake shaft 2 rotate. At the flow port 75 ( Figure 11) When the opening of () is at its maximum, the two passive disk plates 4 slide in opposite directions. When one of the passive disk plates 4 moves towards the inner wall of the housing 1 to squeeze the magnetorheological fluid in the corresponding extrusion cavity 6, the other passive disk plate 4 retracts inward, forming an underpressure cavity in the corresponding extrusion cavity 6. The magnetorheological fluid is sucked into the underpressure cavity. When a second excitation coil 8 generates a magnetic field inside the brake disk 3 in the middle, it will cause the magnetorheological fluid to be locally quasi-solidified in the groove 43 of the passive disk plate 4. During the rotation of the brake disk 3 with the brake shaft 2, the magnetorheological fluid that is locally quasi-solidified in the groove 43 of the passive disk plate 4 is discharged towards the periphery of the brake disk 3 along the groove formed by the two adjacent centrifugal blades 31 of the brake disk 3 under the action of centrifugal force. During this process, the centrifugal blades 31 and the groove 43 of the passive disk plate 4 knead and stir the agglomerated magnetorheological fluid. The kneaded and stirred magnetorheological fluid is sucked into another extrusion cavity 6 through the communication port 118 to form an underpressure cavity.

[0069] It can be understood that in other embodiments, the flow regulating valve 71 and the shape memory alloy spring 73 can also be directly connected by welding or other means to drive the flow regulating valve 71 to reset through the shape memory alloy spring 73. At this time, the reset member 76 can be omitted. However, since the connection between the shape memory alloy spring 73 and the flow regulating valve 71 may accidentally break after long-term use, if the reset member 76 is provided, it can ensure that the flow regulating valve 71 can be reset in time, ensuring the performance of the magnetorheological brake.

[0070] The above description is a detailed description of the preferred and feasible embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. Any equivalent changes or modifications made under the technical spirit disclosed by the present invention shall fall within the scope of the patent covered by the present invention.

Claims

1. A reciprocating extrusion magnetorheological fluid brake, characterized in that, Comprising: A housing (1); Two brake shafts (2), the two brake shafts (2) are arranged coaxially and oppositely and are rotatably connected to the housing (1); Three brake discs (3), the three brake discs (3) are arranged in the housing (1) at intervals along the axial direction of the brake shaft (2), the two outermost brake discs (3) are respectively fixedly connected to the two brake shafts (2), and the space formed by enclosing every two adjacent brake discs (3) and the housing (1) enclose a squeezing chamber (6), and the two squeezing chambers (6) are communicated through a connecting channel (119) arranged in the housing (1); Two passive disc plates (4), the two passive disc plates (4) are respectively slidably arranged in the two squeezing chambers (6), and the passive disc plate (4) is connected to the adjacent two brake discs (3) through a connecting member (9) to reciprocate radially along the brake shaft (2) when the brake disc (3) rotates, and the sliding directions of the two passive disc plates (4) are opposite; A first excitation coil (5), the first excitation coil (5) is fixed in the housing (1) and is arranged around the outer peripheral side of the brake disc (3); Magnetorheological fluid, arranged to flow in the housing (1); and A flow rate regulating assembly (7), including a flow rate regulating valve (71) and a shape memory alloy spring (73), the flow rate regulating valve (71) is slidably installed in the connecting channel (119), and a flow rate port (75) for the magnetorheological fluid to pass through is formed between the flow rate regulating valve (71) and the end of the connecting channel (119); the shape memory alloy spring (73) is arranged at one end of the flow rate regulating valve (71); when the temperature of the magnetorheological fluid rises, the shape memory alloy spring (73) is affected by the temperature and drags the flow rate regulating valve (71) to move along the connecting channel (119) so as to adjust the size of the flow rate port (75).

2. The reciprocating extrusion type magnetorheological fluid brake according to claim 1, characterized in that, The flow rate regulating assembly (7) further includes a reset member (76), the reset member (76) and the shape memory alloy spring (73) are respectively arranged on opposite sides of the flow rate regulating valve (71), and when the temperature of the magnetorheological fluid decays, the reset member (76) can drive the flow rate regulating valve (71) to reset.

3. The reciprocating extrusion type magnetorheological fluid brake according to claim 1, wherein The flow rate regulating valve (71) includes a body portion (711) and a convex platform (713) protruding from one end of the body portion (711), a slope (715) is arranged at the connection between the convex platform (713) and the body portion (711), the slope (715) faces the squeezing chamber (6), and a gap for the magnetorheological fluid to pass through is formed between the body portion (711) and the inner wall of the connecting channel (119); the flow rate regulating valve (71) can move along the connecting channel (119) between a maximum open position and a closed position, when the flow rate regulating valve (71) is in the closed position, the convex platform (713) contacts the inner wall of the connecting channel (119) to close the connecting channel (119); during the process of the flow rate regulating valve (71) moving from the closed position to the maximum open position, different-sized flow rate ports (75) are formed between the slope (715) and the end of the connecting channel (119); the opposite ends of the shape memory alloy spring (73) respectively abut against the body portion (711) and the inner wall of the housing (1).

4. The reciprocating extrusion type magnetorheological fluid brake according to claim 2, wherein The flow regulating valve (71) further includes a guide rod (716). The guide rod (716) is fixedly connected to the body portion (711) and is slidably connected to the housing (1) to guide the movement of the flow regulating valve (71).

5. The reciprocating extrusion type magnetorheological fluid brake according to claim 1, wherein The connecting member (9) includes a connecting rod (91) and a slider (93) fixedly sleeved on the connecting rod (91). The connecting members (9) on the two passive disk plates (4) are respectively arranged on opposite sides of the center of the brake disk (3). The connecting rod (91) is fixedly connected to the adjacent two brake disks (3). The passive disk plates (4) are provided with sliding holes (41) corresponding to the sliders (93), and the two sliders (93) are respectively slidably arranged in the sliding holes (41) of the corresponding passive disk plates (4).

6. The reciprocating extrusion type magnetorheological fluid brake according to claim 1, characterized in that, The number of the first excitation coils (5) corresponds to three brake disks (3), and the three first excitation coils (5) are respectively arranged around the outer peripheral sides of the three brake disks (3).

7. The repeated extrusion type magnetorheological fluid brake according to claim 1, characterized in that, A second excitation coil (8) is further provided on the middle brake disk (3).

8. The repeated extrusion type magnetorheological fluid brake according to claim 7, characterized in that, On the end faces of the two outermost brake disks (3), a plurality of centrifugal blades (31) are convexly provided. The centrifugal blades (31) are arranged on the end faces of the corresponding brake disks (3) facing the passive disk plates (4), and the plurality of centrifugal blades (31) are arranged at intervals along the circumferential direction of the brake disks (3).

9. The reciprocating extrusion type magnetorheological fluid brake according to claim 8, wherein, Grooves (43) are provided on both opposite end faces of the passive disk plate (4).

10. The reciprocating extrusion type magnetorheological fluid brake according to claim 1, wherein, One end of the flow regulating valve (71) away from the shape memory alloy spring (73) is further connected with a pulling member (77).

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