Programmable magnetorheological fluid clutch device

Abstract

A system for operating at least one magneto-rheological fluid clutch device can change the amount of torque transfer between a driving member and a driven member in the at least one magneto-rheological fluid clutch device in a first mode by actuating at least one coil in the at least one magneto-rheological fluid clutch device. In a second mode, the system can set a desired residual magnetization level in a magnetic component of the at least one magneto-rheological fluid clutch device by actuating at least one coil in the at least one magneto-rheological fluid clutch device, thereby transmitting torque between the driven member and the driving member.

Description

Technical Field

[0001] The present application relates generally to magnetorheological (MR) fluid clutch apparatuses and the operation of such MR fluid clutch apparatuses. Background Art

[0002] Magnetorheological (MR) fluid clutch devices are known to be useful devices for transmitting motion / force from a drive shaft to a variable degree and have precision and accuracy as well as other advantages. As a result, an increasing number of applications are considering the use of MR fluid clutch devices. In a known configuration, an MR fluid clutch device has a barrel on both an input and an output, wherein the MR fluid is located in an annular gap between the shear planes of the barrel of the input and the barrel of the output. In order to magnetize the MR fluid located in the annular gap, a magnetic field is passed through the barrel which is known to use a material having a high magnetic permeability. For example, steel is commonly used as the material for the barrel of the MR fluid clutch device.

[0003] In some applications, there is a constraint to maintain torque in an MR fluid clutch device without power. Prior art MR fluid clutch devices having magnets in a magnetic circuit are capable of maintaining a fixed torque value when the MR fluid clutch device is not powered, as shown, for example, in PCT Application Publication No. WO 2016168934. In such MR fluid clutch devices, if the applied torque is greater than a fixed design torque corresponding to a magnetic field maintained in the MR fluid shear interface by a magnetizable component, the output portion begins to slip. In this type of MR fluid clutch device, instead of generating a magnetic field in the MR fluid shear interface, the coil of the MR fluid device redirects the magnetic flux of the parallel mounted magnetizable component into a redirection gap. Control of the magnetic flux in the MR fluid shear interface can be controlled with a high bandwidth. When power is removed from the coil, the magnetizable component can return to a state in which it generates a magnetic field in the MR fluid shear region, and the MR fluid clutch device returns to a state in which it provides its fixed design torque without power.

[0004] New solutions are needed in some applications where the slip torque needs to vary depending on the operating state, such as car doors parked on different slopes, vehicle power systems or equipment operating in different conditions (e.g., asphalt, sand, ice, ...), moving parts of equipment that require different torques depending on the application (e.g., CNC machining centers where the torque varies relative to the diameter of the component), or any other application where a programmable clutch may benefit and the construction of the prior art may be functionally limited. Summary of the invention

[0005] An object of the present disclosure is to provide a magnetorheological (MR) fluid clutch device that solves the problems associated with the prior art.

[0006] Thus, according to a first aspect of the present disclosure, there is provided a magnetorheological fluid clutch device comprising: a drive member having at least one first shear surface, the drive member being adapted to be coupled to a torque source; a driven member having at least one second shear surface opposite the at least one first shear surface, the shear surfaces being separated by at least one annular space, the driven member being adapted to be coupled to an output; a magnetorheological (MR) fluid disposed in an MR fluid chamber comprising at least one annular space, the MR fluid being configured to produce a variable amount of torque transfer between the drive member and the driven member when subjected to a magnetic field; at least one coil being actuatable to produce a magnetic field through the MR fluid; and at least one magnetizable component being of a type that maintains a residual magnetization level, the magnetizable component being configured to be exposed to a magnetic field from the at least one coil to achieve the residual magnetization; wherein actuation of the at least one coil causes a change in torque transfer between the driven member and the drive member, and wherein the residual magnetization level produces another magnetic field, thereby causing torque transfer between the driven member and the drive member.

[0007] Further, according to the first aspect, for example, the driving member and the driven member are rotatably connected to the stator.

[0008] Still further, according to the first aspect, for example, the torque source is a motor.

[0009] Still further, according to the first aspect, for example, the torque source is a structure that provides braking power.

[0010] Still further according to the first aspect, for example, at least one magnetizable component is annular.

[0011] Still further, according to the first aspect, for example, the at least one magnetizable component includes a plurality of discrete magnetizable components distributed circumferentially in the magnetorheological fluid clutch device.

[0012] Still further according to the first aspect, for example, at least one magnetizable component is axisymmetric.

[0013] Still further, according to the first aspect, for example, at least one first shear surface is part of the input barrel, and at least one second shear surface is part of the output barrel.

[0014] Still further, according to the first aspect, for example, the magnetizable component is made of AlNiCo.

[0015] Still further, according to the first aspect, for example, there is provided a system comprising at least one magnetorheological fluid clutch device as described above and comprising a controller for operating at least one coil.

[0016] Still further, according to the first aspect, for example, the torque source is a motor, and the system includes the motor.

[0017] Still further in accordance with the first aspect, for example, at least one magnetorheological fluid clutch device is operably connected to the door.

[0018] According to a second aspect of the present disclosure, a system for operating at least one magnetorheological fluid clutch device is provided, the system comprising a processing unit and a non-transitory computer-readable memory, the non-transitory computer-readable memory being communicatively coupled to the processing unit and comprising computer-readable program instructions executable by the processing unit for: in a first mode, changing the amount of torque transfer between a driving member and a driven member in at least one magnetorheological fluid clutch device by actuating at least one coil in the at least one magnetorheological fluid clutch device, and in a second mode, setting a desired residual magnetization intensity level in a magnetic component of the at least one magnetorheological fluid clutch device by actuating at least one coil in the at least one magnetorheological fluid clutch device, thereby transferring torque between the driven member and the driving member.

[0019] Further, according to the second aspect, for example, the torque source connected to the drive member is decelerated in the second mode.

[0020] Still further, according to the second aspect, for example, the torque source connected to the drive member is stopped in the second mode.

[0021] Still further, according to the second aspect, for example, in a third mode, an amount of torque transfer between a driving member and a driven member in at least one magnetorheological fluid clutch device is changed by actuating at least one coil in the at least one magnetorheological fluid clutch device to a current level below a current level corresponding to a desired residual magnetization level.

[0022] Still further, according to the second aspect, for example, a desired residual magnetization level is removed.

[0023] Still further, according to the second aspect, for example, in the first mode, when the driven member applies a force to displace the door, changing the amount of torque transmission is performed.

[0024] Still further, according to the second aspect, for example, when the driven member holds the door in a desired position, torque is transmitted between the driven member and the driving member.

[0025] Still further, according to the second aspect, for example, the driven member holds the door in a desired position by one of the magnetorheological fluid clutch devices being a magnetorheological fluid brake device.

[0026] According to another aspect of the present disclosure, a magnetorheological fluid clutch device is provided, the magnetorheological fluid clutch device comprising: a stator adapted to be connected to a structure, the stator having at least one annular wall; a first rotor rotatably mounted to the stator, the first rotor having at least one first shear surface; a second rotor rotatably mounted to the stator for rotation about an axis common to the first rotor, the second rotor having at least one second shear surface opposite the at least one first shear surface, the shear surfaces being separated by at least one annular space; a magnetorheological (MR) fluid in an MR fluid chamber including at least one annular space, the MR fluid being configured to produce a variable amount of torque transfer between the rotors when subjected to a magnetic field; an inner magnetic core and an outer magnetic core, wherein the inner magnetic core is connected to at least one of the rotors for rotation with the at least one rotor to be rotatably mounted to the stator a rotor, an outer magnetic core connected to at least one of the rotors for rotation therewith to be rotatably mounted to the stator; an outer fluid gap and an inner fluid gap located between the inner magnetic core and the annular wall and between the outer magnetic core and the annular wall, the outer fluid gap and the inner fluid gap being completely filled with a fluid; at least one coil supported by the annular wall and actuatable to generate a magnetic field through the MR fluid, the magnetic field following a path including the annular wall, the outer fluid gap, the outer magnetic core, at least one first shear plane and at least one second shear plane, the inner magnetic core and the inner fluid gap; wherein one of the rotors is adapted to be coupled to a power input and another of the rotors is adapted to be coupled to an output, whereby actuation of the at least one coil causes a change in torque transfer between the rotors; and wherein a portion of the magnetic circuit is made of a hard or semi-hard magnetic material of a type having a level of residual magnetization retained.

[0027] According to another aspect of the present disclosure, a magnetorheological fluid clutch or brake device is provided, comprising: a first rotor rotatably connected to a structure, the first rotor having at least one first shear surface; a second rotor rotatably mounted to a stator for rotation about an axis common to the first rotor, the second rotor having at least one second shear surface opposite the at least one first shear surface, the shear surfaces being separated by at least one annular space; a magnetorheological (MR) fluid disposed in an MR fluid chamber including the at least one annular space, the MR fluid being configured to produce a variable amount of torque transfer between the rotors when subjected to a magnetic field; an inner magnetic core and an outer magnetic core, wherein the inner magnetic core connected to at least one of the rotors, the outer magnetic core connected to at least one of the rotors; at least one coil supported by the annular wall and actuatable to generate a magnetic field through the MR fluid, the magnetic field following a path including the annular wall, the outer fluid gap, the outer magnetic core, at least one first shear plane and at least one second shear plane, the inner magnetic core and the inner fluid gap; wherein one of the rotors is adapted to be coupled to a power input and another of the rotors is adapted to be coupled to a structure whereby actuation of the at least one coil causes a change in torque transfer between the rotors; and wherein a portion of the magnetic circuit is made of a hard or semi-hard magnetic material of a type that retains a level of residual magnetization. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a schematic diagram of a general magnetorheological (MR) fluid clutch device incorporating features of the present disclosure;

[0029] Figure 2 According to an embodiment Figure 1 A schematic cross-sectional view of an MR fluid clutch device;

[0030] Figure 3 According to another embodiment Figure 1 A schematic cross-sectional view of an MR fluid clutch device;

[0031] Figure 4 According to yet another embodiment Figure 1 A schematic cross-sectional view of an MR fluid clutch device;

[0032] Figure 5 According to yet another embodiment Figure 1 A schematic cross-sectional view of an MR fluid clutch device;

[0033] Figure 6 According to yet another embodiment Figure 1 A schematic cross-sectional view of an MR fluid clutch device;

[0034] Figure 7is a diagrammatic representation of a magnetization process of an MR fluid device according to an aspect of the present disclosure;

[0035] Figure 8 is a schematic cross-sectional view of an MR fluid brake apparatus incorporating features of the present disclosure;

[0036] Fig. 9 is a schematic cross-sectional view of an MR fluid clutch device or an MR fluid brake device according to yet another embodiment;

[0037] Fig.10 is a diagram showing a group of magnetic materials in three categories;

[0038] Fig.10 ' is a series of BH curves for various magnet types as may be used in the MR fluid clutch device of the present disclosure;

[0039] Fig.11 is a diagram of an exemplary demagnetization process of an MR fluid device according to an aspect of the present disclosure;

[0040] Fig.12 is a schematic diagram featuring a system having an MR fluid device for use with a vehicle door;

[0041] Fig.13 is a schematic diagram of another system featuring an MR fluid device for use with a vehicle door;

[0042] Fig.14 is a schematic diagram of another system featuring an MR fluid device for use with a vehicle door;

[0043] Fig.15 is a schematic cross-sectional view of an MR fluid clutch device according to yet another embodiment; and

[0044] Fig.16 According to yet another embodiment Figure 1 Schematic cross-sectional view of an MR fluid clutch device. DETAILED DESCRIPTION

[0045] With reference to the drawings and more particularly with reference to Figure 1, a magnetorheological (MR) fluid clutch device 10 is shown, which is configured to provide a mechanical output force based on a received input current and to provide a force based on the residual magnetization level of a magnetizable component in a magnetic circuit in the absence of an input current. The MR fluid clutch device 10 is shown as a type having a co-linear input shaft 11 and an output shaft 12. However, the concepts described herein can be applied to other configurations of MR fluid clutch devices, such as some having an input or output housing / cover for an output shaft or an input shaft, etc. The principles shown here will be implemented using a cartridge-type MR fluid clutch device, but can also be applied to a disc-type MR fluid clutch device. In addition, the MR fluid clutch device 10 can also be used as a brake, where, for example, the input portion is fixed to a structure. The expression of an MR fluid clutch device can therefore include an MR fluid brake device. When the expression of an MR fluid brake device is used herein, it relates to an MR fluid clutch device specifically for injecting a braking force. In some embodiments, the MR fluid clutch device 10 is part of an MR fluid actuator that may include the device 10 and a power source such as a motor, an optional transmission between the motor and the device 10, such as a gear reduction box, or the like.

[0046] The MR fluid clutch device 10 can provide an output force in response to an input current received from an operator, and transmit an input force and an output force based on the magnetization level of a magnetizable component in a magnetic circuit when no input current is present. An exemplary MR fluid clutch device 10 can have a stator 10A, which is a structure to which the MR fluid clutch device 10 is connected. The MR fluid clutch device 10 is characterized by having a driven member 11 and a driving member 12 separated by a gap filled with MR fluid, as explained below. The driving member 12 can receive rotational energy (torque) from a power device (e.g., a motor) with or without a transmission device (e.g., a gear reduction box, etc.).

[0047] According to an embodiment, the driving member 12 may be in mechanical communication with a power input (directly or through a transmission), and the driven member 11 may be in mechanical communication with a power output (i.e., a force output, a torque output). The stator 10A, the driven member 11, and the driving member 12 may be interconnected by bearings 12A and 12B. In the illustrated embodiment, the bearing 12A is between the stator 10A and the driving member 12, and the bearing 12B is between the driven member 11 and the driving member 12. One or more seals 12C may also be provided at the interface between the stator 10A, the driven member 11, and the driving member 12 to retain the MR fluid between the members 11 and 12. In addition, the seal 12C is provided to prevent the MR fluid from reaching the bearing 12B or leaking from the device 10.

[0048] As the following reference Figures 2 to 4As shown, the cylinders are positioned circumferentially around the axis of rotation CL. Therefore, some of the supports must extend substantially radially to support the cylinders in their circumferential arrangement. According to one embodiment, reference Figure 2 , a low magnetic permeability input cylinder support 13 (also known as a radial wall) protrudes radially from the shaft of the driving member 12. The input cylinder support 13 can be connected to the input rotor 14, thereby defining an outer cover or housing of the MR fluid clutch device 10. Therefore, the input rotor 14 can be rotatably connected to the driven member 11 through the bearing 12B. In an embodiment, the input rotor 14 has an input rotor support 14A that forms a housing for the bearing 12B. According to an embodiment, the input rotor support 14A is an integral part of the input rotor 14, and they can be manufactured as a single piece. However, in an embodiment, the input rotor support 14A is ideally made of a low magnetic permeability material, and the input rotor 14 is made of a high magnetic permeability material. As another embodiment, Figure 2 As shown, the input rotor support 14A can be defined by an annular wall that is manufactured separately from the rest of the input rotor 14, although the two are interconnected for simultaneous rotation. Therefore, the input cylinder support 13, the input rotor 14, and the shaft of the drive member 12 rotate simultaneously. In an embodiment, it is contemplated that the housing of the MR fluid clutch device 10 is a part of the stator 10A or a part of the driven member 11.

[0049] The input cylinder support 13 can support a plurality of concentric annular cylinders 15, also referred to as input annular cylinders. The input annular cylinders 15 are fixed to the input cylinder support 13 and rotate therewith. In an embodiment, concentric circular channels can be defined (e.g., machined, cast, molded, etc.) in the input cylinder support 13 to insert the cylinders 15 therein. Tight fits (e.g., press fits), adhesives, and / or radial pins are some of the mechanical components that can be used to fix the cylinders 15 to the input cylinder support 13. In an embodiment, the input cylinder support 13 is integrally connected to the shaft of the drive member 12, whereby the plurality of components of the drive member 12 rotate simultaneously when receiving drive from a power source.

[0050] The driven member 11 may be represented by an output shaft also configured to rotate about the axis CL. The output shaft 11 may be coupled to a plurality of mechanical components that receive a transmitted power output when the clutch device 10 is actuated to transmit at least some of the rotational power input.

[0051] The driven member 11 also has one or more concentric annular cylinders 16 (also referred to as output cylinders) mounted to an output cylinder support 17. The output cylinder support 17 may be an integral part of the output shaft, or may be mounted on the output shaft for simultaneous rotation. The annular cylinders 16 are spaced apart so that multiple sets of output annular cylinders 16 are assembled in an annular space between the input annular cylinders 15 in a mutually coiled manner. When either the driven member 11 or the driving member 12 rotates, there is no direct contact between the annular cylinders 15 and the cylinders 16 due to their concentricity around the axis CL. Figure 2 In the embodiment of the present invention, the drive member 12 or the input rotor 14 may be composed of a magnetizable (also known as a magnetizable) part (eg, ferrite) or may include a magnetizable part. Alternatively, the input rotor 14 may be composed of a magnetizable part.

[0052] exist Figure 3 In the embodiment of the present invention, the MR fluid clutch device 10 is similar to Figure 2 An MR fluid clutch device in which like reference numerals denote like elements. Figure 3 In the embodiment of the invention, the drive member 12 is divided into two sections 12' and 12", and one or more magnetizable components 31 are located between the two sections 12' and 12" within the magnetic circuit (also known as magnetic path). The concept of two sections 12' and 12" does not necessarily imply that these sections may be separate from each other. The drive member 12 may be an integral component including a magnetizable component 31. The magnetizable component 31 is shown in the drawings of the present disclosure as having different aspects. The magnetizable component 31 is made of a material having the ability to maintain a residual magnetization level after exposure to a magnetic field of a given magnitude, so that the magnetizable component 31 itself generates a magnetic field. Such materials are described in further detail below. The magnetizable component 31 may be annular in shape, for example by forming a ring integrated into multiple components of the MR fluid clutch device 10. As another variation, the magnetizable component 31 may be a plurality of discrete magnetizable components 31. Such discrete magnetizable components 31 may be distributed circumferentially around the central axis of the MR fluid clutch device 10, essentially forming a ring around the central axis. The spacing between the magnetizable components 31 may vary. In another variation, the plurality of discrete magnetizable components 31 are arranged in an axisymmetric manner.

[0053] exist Figure 4 In the embodiment of the present invention, the MR fluid clutch device 10 is similar to Figure 2 An MR fluid clutch device in which like reference numerals denote like elements. Figure 4In the embodiment of the present invention, the input rotor 14 is divided into two sections 14' and 14", and one or more magnetizable components 31 are within the magnetic circuit. In addition, the concept of two sections 14' and 14" does not necessarily imply that these sections may be separated from each other. The input rotor 14 may be an integral component including the magnetizable component 31 and having two sections 14' and 14".

[0054] exist Figure 5 In the embodiment of the present invention, the MR fluid clutch device 10 is similar to Figure 2 An MR fluid clutch device in which like reference numerals denote like elements. Figure 5 In the embodiment of the present invention, the input drum 15 and / or the output drum 16 are made of a lightweight low magnetic permeability material (e.g., plastic, plastic doped with metal particles or aluminum). In addition, the input rotor 14 is provided with a magnetizable component 31, which is located at the fluid (i.e., air) gap between the input rotor 14 and the stator 10A in the magnetic circuit.

[0055] exist Figure 6 In the embodiment of the present invention, the MR fluid clutch device 10 is similar to Figure 5 An MR fluid clutch device in which like reference numerals denote like elements. Figure 5 In the embodiment of the invention, one or more barrels 15 or 16 are replaced by a magnetizable component 31 (aka barrel) as part of the magnetic circuit. Alternatively, one or more barrels 15 or 16 may be coated with a magnetizable component material.

[0056] therefore, Figures 2 to 6 A number of contemplated locations of the magnetizable component 31 in the MR fluid clutch device 10 are shown. In all such aspects, the magnetizable component 31 is within the magnetic circuit and can generate its own magnetic field along the same magnetic circuit or a similar magnetic circuit. It is also observed that there is an annular gap A between the stator 10A and the rotor 14. The annular gap A may be located radially between the stator 10A and the rotor 14, between the stator 10A and the drive member 12, or may be at other locations, in other orientations (axial gaps). The annular gaps A may be referred to as fluid gaps because they are typically filled with a fluid, i.e., air or other non-MR fluid from the environment. The annular gaps A may also be referred to as empty. Some MR fluid clutch devices may not have such gaps.

[0057] exist Figures 1 to 6In the embodiment, the electromagnet unit 18 is supported by the stator 10A and is used to activate and control the clutch function of the MR fluid clutch device 10. The electromagnet unit 18 is shown schematically, but the electromagnet unit can conventionally have a toroidal coil and core to form an electromagnet, all necessary wiring to generate a variable magnetic field. According to an embodiment, these annular spaces have a width of 0.25 mm to 1 mm between the facing surfaces of the set of cylinders 15 and 16 (i.e., in the radial direction). The width range of the annular space is provided only as a non-exclusive example, because other annular space widths are also considered taking into account various factors such as overall torque, component size, viscous resistance, etc.

[0058] The annular space between the annular cylinder 15 of the driving member 12 and the annular cylinder 16 of the driven member 11 is filled with an MR fluid 19. The MR fluid 19 used to transmit force between the driven member 11 and the driving member 12 is a type of smart fluid composed of magnetizable particles disposed in a carrier fluid (usually a type of oil). When subjected to a magnetic field, the fluid can increase its apparent viscosity, potentially to the point of becoming a viscoplastic solid. The apparent viscosity is defined by the ratio between the operating shear stress and the operating shear rate of the MR fluid included between the opposing shear planes. The magnetic field strength mainly affects the yield shear stress of the MR fluid. The yield shear stress of the fluid can be controlled by changing the magnetic field strength (i.e., input current and / or residual magnetization level via the magnetizable component 31) generated by the electromagnet when in its startup ("on") state using a controller. The effective magnetic flux in the MR fluid can be the sum of the two. Therefore, the ability of the MR fluid to transmit force can be controlled by the electromagnet so that the MR fluid acts as a clutch between the members 11 and 12. The electromagnet unit 18 is configured to change the strength of the magnetic field so that the friction between the members 11 and 12 can be low enough to allow the driving member 11 to rotate freely relative to the driven member 12, and vice versa. Therefore, the MR fluid clutch device 10 can change the amount of force provided by changing the amount of magnetic flux exposed to the MR fluid 19 in response to the received input. Specifically, the MR fluid clutch device 10 can provide an output force based on the input force by changing the amount of magnetic flux based on the input force.

[0059] The annular space between each set of barrels 15 and 16 is a portion of the MR fluid chamber sealed by one or more seals. In addition to the space at the end of the barrel top and the space between the barrels 15 and 16 and the shear surface (these shear surfaces are part of the shaft of the drive member 12 and the input rotor 14), the MR fluid chamber also includes a set of annular spaces between the barrels 15 and 16. The MR fluid chamber may also include an annular space 20 located opposite to the output barrel support 17, although such annular space 20 may not exist. According to an embodiment, the flow of the MR fluid is as follows. When the drive member 12 rotates, some pumping action can be generated by the input barrel 15, through which the MR fluid 19 moves in a radially outward direction after reaching the ends of the barrels 15 and 16. When exceeding the outermost barrel 16, the MR fluid 19 can be guided to pass through the radial edge of the output barrel support 17 and enter the annular space 20. MR fluid 19 will move radially inwardly through the holes in output barrel support 17 to return to the other side of output barrel support 17 to circulate between barrels 15 and 16. Space 20 may be in fluid communication with an expansion system 23. This is one other example of MR fluid circulation.

[0060] Movement of the MR fluid in the manner described above allows the MR fluid to circulate in the MR fluid chamber. This movement may be achieved via the presence of a spiral channel on the surface of the barrel 15. Other surface depressions or localized changes in magnetic permeability may also be used on either the set of barrels 15 or the set of barrels 16 to induce a pumping action in the MR fluid chamber, i.e., some form of cavity, protrusion, or channel in an otherwise smooth cylindrical surface.

[0061] When current is passed through the electromagnet unit 18, a magnetic field is generated in a magnetic circuit or magnetic path including the magnetizable component 31, the mutually coiled arrangement of the barrel 15 and the barrel 16, and the shear plane of the shaft 12 and the shear plane of the input rotor 14 (with the MR fluid 19 interposed therebetween). Therefore, the magnetic field increases the apparent viscosity of the MR fluid 19 to grab the barrel 15 and the barrel 16 so that the rotational motion is transmitted from the input barrel 15 to the output barrel 16. The mutually coiled arrangement of the barrel 15 and the barrel 16 allows the total clutch shear surface per volume of the MR fluid 19 to be increased. The electromagnet unit 18 is used to increase the magnetic field in the magnetic circuit. Because the magnetic circuit includes the magnetizable component 31, the magnetizable component 31 can be magnetized when current is passed through the toroidal coil 18. When the current is removed, the magnetizable component 31 remains magnetized due to its hysteresis behavior, but at a lower level than the magnetic field once applied to the magnetic circuit. In the illustrated embodiment, the radial fluid gaps A between the input rotor 14 and the stator 10A and between the shaft 12 and the stator 10A are radial rather than axial, although axial gaps are contemplated. It may be desirable to use radial gaps A because radial tolerances are easily achieved so that the fluid gaps can be quite small (<0.2 mm), and thus the number of extra turns in the coils required to magnetize the fluid gaps 34A and 34B is minimized. In addition, due to the rotational symmetry of the fluid gaps on opposite sides of the stator 10A, the magnetic attraction forces in the fluid gaps A between the stator 10A and both the magnetic input rotor 14 and the shaft 12 can be nearly canceled.

[0062] refer to Fig. 9 , shows an MR fluid clutch device 70 having a disk instead of a cylinder. The MR fluid brake device and the MR fluid brake device 70 are similar to Figures 1 to 7 1. The MR fluid brake device 10 of the present invention is shown in FIG. 1, wherein like reference numerals denote like elements. In this embodiment, the cylinder is replaced by discs 71 and 72. One or more input discs 71 are connected to the drive member 12, while one or more output discs 72 are connected to the stator 10A.

[0063] In such a one or more disc type MR fluid clutch device, when the magnetic circuit is not completely balanced, the force generated by the coil or magnetizable component 31 generates an axial load on the bearing. Because wear may cause the components to move axially over time, the axial load generated in the bearing may affect durability and may have an impact on the reliability of the system. The higher the degree of axial eccentricity of the one or more discs, the more axial load it will generate in the bearing, which will increase the wear rate proportionally. In addition, the disc type MR fluid clutch device 70 equipped with the magnetizable component 31 may be more difficult to control because the plate may bend under the axial load generated on the disc 71 or 72. For a multiple disc type device, a small gap may be more difficult to maintain because of the accumulation of very tight axial tolerances.

[0064] Figure 7 FIG. 2 shows an example of the relationship (solid line) between the torque (T) generated in the MR fluid clutch device 10 and the current (I) in the electromagnet unit 18 assuming that the magnetizable member 31 is initially demagnetized. sat When horizontal, the effective torque generated by the MR fluid clutch device 10 may correspond to T sat level (the maximum level that the MR fluid clutch device 10 can reach). When the current is removed in the electromagnet unit 18, the magnetizable component 31 will maintain the magnetization level of the magnetic circuit due to its hysteresis characteristics, and the MR fluid clutch device 10 will generate a torque T even if the current is removed in the electromagnet unit 18 (i.e., I=0A). sat0 Similarly, when the current in the electromagnet unit 18 is at level I d When the effective torque generated by the MR fluid clutch device 10 can correspond to the level T d , when the current is removed in the electromagnet unit 18, the magnetizable component 31 will maintain the magnetization level of the magnetic circuit due to its hysteresis characteristics, and the MR fluid clutch device 10 will generate a torque T d0 , even if the current is removed from the electromagnet unit 18 (i.e., I=0A). By using an appropriate current I in the electromagnet unit 18, the magnetizable component 31 can be magnetized, and the effective MR fluid clutch device 10 torque can be adjusted to 0 to T when there is no current in the electromagnet unit 18. sat0 It should be noted that not all current levels in the electromagnet unit 18 will affect T d0 When the current is kept at I d In the case of a condition where a current exceeding T d0 The torque magnetic field, therefore, does not affect its "programmed" T d0 In the case of a torque that is temporarily increased by the MR fluid clutch device 10, the torque generated by the MR fluid clutch device 10 is temporarily increased. For example, the expression "programmed" may be interpreted as a synonym for a set torque, a desired torque, a selected torque. Alternatively, by injecting a negative current into the MR fluid clutch device 10, the torque generated by the MR fluid clutch device 10 may be temporarily increased without affecting its "programmed" torque. d0 In the case of a short circuit, the torque generated by the MR fluid clutch device 10 is temporarily reduced. By keeping the current at a level that does not affect T d0 value range (i.e., Figure 7 Middle I d At or below), the MR fluid clutch device 10 can be operated (where T d0 The value can be programmed to low bandwidth) so that high bandwidth can be used at T d0The torque produced by the MR fluid clutch device 10 is finely tuned around the periphery. The ability to tune the torque at a high bandwidth will be affected by the type of magnet used for the magnetizable member 31 which may need to be selected differently for a particular application and adjustable range.

[0065] Figure 8 Shows something like Figure 2 The MR fluid clutch device 10 is an MR fluid brake device 50, wherein like reference numerals represent like elements. Figure 8 , the drive member 12 and the stator 10A are now attached together as non-moving parts so as to act as a brake when the stator 10A is mounted on a chassis (not shown). The torque generated by the MR fluid brake device 50 is similar to Figures 1 to 7 The MR fluid clutch device 10 of the MR fluid brake device, and the magnetizable component 31 can be located at any suitable position, such as Figures 2 to 6 Those locations shown in .

[0066] Fig.10 Various types of materials from which the magnetizable component 31 may be made are shown. In the illustrated embodiment, the magnetizable component 31 is ideally made of a semi-hard or hard magnetic material with a high coercivity. This may show the following advantages: although semi-hard or hard magnetic materials are generally more expensive than soft magnetic materials (i.e., standard carbon steel), hard magnetic materials with high magnetic retention are used in the magnetic circuit of the MR fluid clutch device 10 and 70 (including the brake 50) in order to keep the size and weight of the magnetic material to a minimum. However, semi-hard or hard magnetic materials may require more energy per volume to magnetize or demagnetize, and may have a higher hysteresis. In the MR fluid device of the present disclosure, it is known that hysteresis reduces the bandwidth of the device. If the volume of the magnetizable material 31 should be reduced to a minimum to achieve a more economical solution, the use of hard materials may represent a better choice. However, due to its higher hysteresis, the use of hard materials may compromise the bandwidth of the MR fluid clutch 10 or brake 50 device. If the bandwidth of the MR fluid clutch 10 or brake 50 device is important, the use of a semi-rigid material may represent a better choice for the magnetizable material 31, but will be at a cost penalty because more volume of magnetizable material 31 will be required to produce a given magnetic flux when no current is generated in the coil 18.

[0067] Fig.10 'Shows Fig.101 and 2. Example saturation curves (aka, BH curves of applied external magnetic field H versus total magnetic flux density B) of some types of magnetic materials that can be made into the magnetizable component 31. The material with the highest residual field Br can allow the cross-section of the magnetic circuit of the MR fluid clutch device 10 to be minimized. Therefore, hard magnets like NdFeB, SmCo, and semi-hard materials like AlNiCo are very suitable for use as the magnetizable component 31. The magnetization level of a magnetic material is directly related to its inherent operating point on the inherent BH curve. The inherent operating point of a magnetic material is defined by a loading line, which is determined by the magnetic circuit characteristics and the external magnetic field, which is generated by the current applied in the coil of the electromagnet unit 18 of the MR fluid clutch device 10. By increasing the demagnetization current in the coil of the electromagnet unit 18, the loading line is shifted to the left. When the inherent operating point is below the inflection point of the inherent BH curve, the magnetic material will lose some energy after the current in the coil of the electromagnet unit 18 is removed. The difference between a hard material, such as NdFeB N48SH, and a semi-hard material, such as AlNiCo, is the location of the inflection point in the intrinsic BH curve. For AlNiCo, the intrinsic curve is very similar to the normal curve, so demagnetization is easy to achieve. In contrast, for NdFeB, a higher current in the coil is required to reach the inflection point of the intrinsic BH curve, and therefore a higher current in the coil is required to demagnetize the hard material. NdFeB belongs to the family of rare earth magnets and is not as easily available as AlNiCo. In addition, depending on the grade of the magnet, the magnetic properties of NdFeB can be changed by temperature and may not be suitable for applications requiring temperature stability, such as in automotive applications requiring stability between -30 degrees Celsius and 80 degrees Celsius. AlNiCo is less sensitive to temperature changes and is therefore suitable for applications involving temperature changes.

[0068] Fig.11 A demagnetization process is shown that may be required to reduce the residual magnetization level of the magnetizable component 31 to close to zero, such as driven by the electromagnet unit 18. Since the magnetizable component 31 is selected to have high hysteresis, the use of the demagnetization process can present its advantages. An alternating current is applied to the coil 18. The controller can start by generating a higher current in the coil 18, and reducing it until it is zero, and then generating a reverse current in the coil 18 at a level lower than the previous current, continuing until the level of the alternating current reaches close to zero. The alternating current switches direction quickly, thereby changing the orientation of the electromagnetic field. The magnetic dipoles in the magnetizable component 31 try to orient according to the field, but as the field changes, they eventually randomize. The core of the material can maintain a slight magnetic field due to hysteresis, but when no current is supplied to the coil 18, a residual magnetic field of zero overall can be obtained in the magnetic circuit.

[0069] Figure 12 to Figure 14is an exemplary embodiment of an application in which the MR fluid clutch device of the present disclosure (ie, an MR fluid clutch device (including an MR fluid brake device) characterized by including a magnetizable component 31) can be used. Fig.12 In the embodiment of the present invention, the MR fluid clutch device 70 can be used to control the opening force of the door with a high bandwidth, as explained in PCT Application Publication No. WO 2017083970. At the same time, the MR fluid clutch device 70 can also be used to brake the door 120 even if there is no power supplied to the MR fluid clutch / brake device 10 and 70. In the present application, the MR fluid brake device can be programmed to output the torque required to hold the door in a given position, but if an external force is provided on the vehicle door 120, the force required to move the door is kept to a low level. When used in a first mode (such as an actuation mode), the motor M to which the MR fluid clutch device 10 is coupled is activated, and the MR fluid clutch device 10 is kept slipping to control the amount of torque to the door 120. The MR fluid brake device 70 is deactivated (programmed to 0 Nm). The clutch current in the coil 18 is electronically controlled to vary the force applied at the gearbox G with a high bandwidth (>15 Hz). When the door 120 reaches the desired position measured by the position encoder P, the MR fluid clutch device 10 stops transmitting torque and stops the door. The resulting "holding torque" can be recorded. The motor M can be decelerated to a lower speed, and the MR fluid clutch device 10 can maintain the "holding torque". When an external force is applied to the door 120, such as by a person (or wind) pushing on the door 120, the door 120 can move with very low external force. The door 120 can move with the assistance of the MR fluid clutch device 10. A torque sensor can be used, but it is not required. If the system needs to reduce its power consumption, then as explained previously, the "holding torque" can be programmed into the MR brake 70, and the motor M and / or the MR fluid clutch device 10 can be deactivated. In the present application, the motor of the system can be turned off, but the MR fluid brake device 70 maintains the "holding torque" without power because the torque is braked on the structure rather than on the motor that can be reversely driven. Such a second mode can be called a holding mode (or setting mode, or program setting mode) because the MR fluid brake device 70 uses its residual magnetization to hold the door 120. When an external force such as a person (or wind) pushes on the door 120, the door 120 can move with very low force without the need for a torque sensor. When the door 120 moves, the MR fluid clutch device 10 can return to the actuation mode, and the MR fluid brake device 70 can be used in a Fig.11The MR fluid brake device 70 is demagnetized in the manner shown to have zero braking force programmed into the MR fluid brake device 70. This last mode may be useful when the vehicle's door is closed, and it is desired that a minimum braking force be present so as not to restrict manual door opening of the vehicle. To achieve this type of operation, a controller C may be connected to multiple components of the system. The controller C may include one or more processing units C1 and a non-transitory computer readable memory C2, the non-transitory computer readable memory being communicatively coupled to the processing unit C1 and including computer readable program instructions executable by the processing unit for operating the system described above. The controller C may include a database in the memory C2 that includes characteristics of the magnetizable components, such as Figure 7 , Fig.10 'and Fig.11 , so that the controller C has the ability to drive the electromagnet unit 18 to set the desired holding torque.

[0070] The controller C can therefore be operated in the following manner Fig.12 and the systems shown in the subsequent figures or any MR fluid clutch device described herein: in a first mode, changing the amount of torque transmission between a driving member and a driven member in at least one magnetorheological fluid clutch device by actuating at least one coil in at least one magnetorheological fluid clutch device; in a second mode, setting a desired residual magnetization level in a magnetic component of at least one magnetorheological fluid clutch device by actuating at least one coil in at least one magnetorheological fluid clutch device, thereby transmitting torque between the driven member and the driving member; in the second mode, decelerating a torque source connected to the driving member; in the second mode, decelerating a torque source connected to the driving member the torque source being stopped; in a third mode, changing the amount of torque transferred between the driving member and the driven member in at least one magnetorheological fluid clutch device by actuating at least one coil in the at least one magnetorheological fluid clutch device to a current level below a current level corresponding to a desired residual magnetization level; removing the desired residual magnetization level; when the driven member applies a force to displace the door, changing the amount of torque transferred in the first mode; when the driven member holds the door in a desired position, transferring torque between the driven member and the driving member; and / or holding the door in a desired position by one of the magnetorheological fluid clutch devices being a magnetorheological fluid brake device.

[0071] Fig.13 is another exemplary embodiment of a typical application that can use only the MR fluid clutch device 10. The MR fluid clutch device 10 is used instead of the MR fluid brake device 70, so the architecture is similar to Fig.12In this application, the drive member 12 (not shown) of the MR fluid clutch device can be connected to a non-reverse-driven power system so that when power is not provided, the power system may not rotate relative to the chassis (not shown). In this application, the MR fluid clutch device 10 can be used to Fig.12 The system has a low bandwidth to control the opening force of the door because of the presence of a magnetizable component 31 (not shown) in the magnetic circuit. In the present application, the MR fluid clutch device 10 can be programmed to output the torque required to hold the door in a given position, and the force required to move the door is kept to a low level if an external force is provided on the vehicle door 120. When used in the actuation mode, the motor is started and the MR fluid clutch device 10 is kept sliding to control the amount of torque applied to the door 120. The current in the coil 18 is electronically controlled to vary the force applied at the gearbox with an average bandwidth (>1 Hz). When the door 120 reaches the desired position measured by the position encoder, the MR fluid clutch device 10 stops transmitting torque so that the door 120 stops. The resulting "holding torque" can be recorded. In the holding mode, the motor can be decelerated to a low speed, and the MR fluid clutch device 10 can maintain the "holding torque" in the MR fluid clutch device 10. When an external force is applied to the door 120, such as by a person (or wind) pushing on the door 120, the door 120 can be moved with very low force. The door 120 can be moved and the system can assist in the movement. A torque sensor can be used, but is not required. If the system needs to reduce its power consumption, then as previously explained, a "holding torque" can be programmed or set in the MR clutch 10, and the motor and / or MR fluid clutch device 10 can be unpowered. In the present application, the system can be shut down and the MR fluid clutch device 10 maintains a "holding torque" without power because the torque is braked on the non-backdriveable motor. When a person (or wind) pushes on the door 120, the door 120 can be moved with very low force without the need for a torque sensor. When the door 120 moves, the MR fluid clutch device 10 can return to the actuation mode and as Fig.11 1 to remove the residual magnetization. This last mode may be useful when the vehicle's door is closed and there needs to be a minimum braking force on the actuator to not restrict the manual door opening of the vehicle. At any time, the current in the programmable clutch 10 can be controlled to adjust the transmittable torque. In a specific mode (third mode), the MR fluid clutch device may have been programmed with a residual magnetization level (such as in the holding mode), but the electromagnet unit 18 can be driven at a current lower than that corresponding to the holding torque to adjust the torque transmission.

[0072] Fig.14is another exemplary embodiment of a typical application in which two variations of the MR fluid clutch device 10' and 10" may be used. In the present application, the MR fluid clutch device 10" may be used to control the opening force of the door with a high bandwidth, as explained in WO2017083970. At the same time, the MR fluid clutch device 10' may be used to provide a biasing force to the door 120 even when there is no power supplied to the MR fluid clutch device 10' and 10". In the present application, the MR fluid clutch device 10' may be programmed with a required torque to hold the door in a given position, but if an external force is provided on the vehicle door 120, the force required to move the door is kept to a low level. When used in the actuation mode, the motor M is started and the MR fluid clutch device 10" is kept sliding to control the amount of torque applied to the door 120, while a constant force (DC force) may be generated by the MR clutch device 10'. This configuration may be useful in situations where both low bandwidth force and high bandwidth force (AC force) are required in parallel. Many applications may require this combination of forces. As an example, any helicopter swashplate force used to control the pitch of the blades could benefit from this arrangement. Fig.14 In the embodiment of the present invention, both MR fluid clutch devices 10' and 10" may be connected to a common motor M, although separate motors may be used.

[0073] Fig.15 The embodiment shown is similar to Figure 4 The embodiment of the present invention is different in that the output member 11 (also known as the driven member) is located on the same side as the stator 10A. In addition to the bearings 12A and 12B supporting the drive member 12 on the stator 10A, two bearings 12C and 12D are added to guide the driven member 11. The magnetizable component 31 can be located Figures 2 to 7 1, but is shown as, for example, in the form of a sleeve or ring on the housing of the input rotor. The drive member 12 has an elongated tubular portion concentric with the output member 11, wherein bearings 12C and 12D join the tubular portion to the output member 11. As also observed, the barrel 15 protrudes from the support 13 toward the input end, while the barrel 16 protrudes from the support 17 toward the driven end. The support 13 protrudes radially inwardly from the shell of the input rotor 14.

[0074] Fig.16 is similar to Figure 4 1 is a schematic cross-sectional view of an MR fluid clutch device in FIG. 1 , except that any one of the components defining the input rotor 14 or the drive member 12 is based on a structure. In this configuration, the stator 10A can be made to slide away together with the electromagnet unit 18. In other words, the stator 10A can be regarded as being installed in Fig.16 The stator box is removed and the MR fluid brake device is adjusted to set the holding torque. After the residual magnetization level is set, the stator box is removed and Fig.16 The MR fluid brake device is maintained in the holding mode. Such an embodiment may be useful when the unit only needs to be programmed once in a period of time and in the case of having the electromagnet unit 18 and its associated wires during the application. Such an embodiment may be useful in applications where a programmable mechanical fuse may be required in dusty environments (e.g., buildings) and in applications where the electromagnet unit 18 may be easily damaged.

Claims

1. A magnetorheological fluid clutch device, comprising: a drive member having at least one first shear surface, the drive member adapted to be coupled to a torque source; a driven member having at least one second shearing surface opposite the at least one first shearing surface, the shearing surfaces being separated by at least one annular space, the driven member being adapted to be connected to the output portion; a magnetorheological fluid disposed in a magnetorheological fluid chamber including the at least one annular space, the magnetorheological fluid configured to produce a variable amount of torque transfer between the driving member and the driven member when subjected to a magnetic field; at least one coil, the at least one coil being actuatable to generate a magnetic field through the magnetorheological fluid; as well as at least one magnetizable component, the at least one magnetizable component being of a type that maintains a level of residual magnetization, the at least one magnetizable component being configured to be exposed to the magnetic field from the at least one coil to achieve the residual magnetization; wherein actuation of the at least one coil causes a change in torque transmission between the driven member and the driving member, and The residual magnetization level generates another magnetic field, thereby transmitting torque between the driven member and the driving member.

2. The magnetorheological fluid clutch device according to claim 1, wherein: The driving member and the driven member are rotatably connected to a stator.

3. The magnetorheological fluid clutch device according to any one of claims 1 and 2, wherein: The torque source is an electric motor.

4. The magnetorheological fluid clutch device according to claim 1, wherein: The torque source is a structure that provides braking power.

5. The magnetorheological fluid clutch device according to any one of claims 1 and 2, wherein: The at least one magnetizable component is annular.

6. The magnetorheological fluid clutch device according to any one of claims 1 and 2, wherein: The at least one magnetizable component comprises a plurality of discrete magnetizable components distributed circumferentially in the magnetorheological fluid clutch device.

7. The magnetorheological fluid clutch device according to claim 5, wherein: The at least one magnetizable component is axisymmetric.

8. The magnetorheological fluid clutch device according to any one of claims 1 and 2, wherein: The at least one first shear surface is part of the input cylinder and the at least one second shear surface is part of the output cylinder.

9. The magnetorheological fluid clutch device according to any one of claims 1 and 2, wherein: The at least one magnetizable component is made of AlNiCo.

10. A system comprising: at least one magnetorheological fluid clutch device according to any one of claims 1 to 9; A controller is provided for operating the at least one coil.

11. The system according to claim 10, wherein: The torque source is an electric machine, and the system includes the electric machine.

12. The system according to any one of claims 10 to 11, wherein: The at least one magneto-rheological fluid clutch device is operatively connected to the door.

13. A system for operating at least one magnetorheological fluid clutch device, comprising: Processing unit; as well as a non-transitory computer-readable memory communicatively coupled to the processing unit and comprising computer-readable program instructions executable by the processing unit for: in a first mode, varying an amount of torque transfer between a driving member and a driven member in the at least one magnetorheological fluid clutch device by actuating at least one coil in the at least one magnetorheological fluid clutch device, and In a second mode, a desired residual magnetization level is set in a magnetic component of the at least one magneto-rheological fluid clutch device by actuating the at least one coil in the at least one magneto-rheological fluid clutch device to transfer torque between the driven member and the driving member.

14. The system of claim 13, comprising decelerating a torque source connected to the drive member in the second mode.

15. The system of claim 14, comprising deactivating the torque source connected to the drive member in the second mode.

16. A system according to any one of claims 13 to 15, comprising: In a third mode, an amount of torque transfer between the driving member and the driven member in the at least one magneto-rheological fluid clutch device is varied by actuating the at least one coil in the at least one magneto-rheological fluid clutch device to a current level below a current level corresponding to the desired residual magnetization level.

17. The system of any one of claims 13 to 15, comprising removing the desired level of residual magnetization.

18. A system according to any one of claims 13 to 15, wherein: In the first mode, varying the amount of torque transfer is performed when the driven member applies a force to displace the door.

19. The system of claim 18, wherein: When the driven member holds the door in a desired position, torque is transferred between the driven member and the driving member.

20. The system of claim 19, wherein: The driven member holds the door in a desired position via a magneto-rheological fluid clutch device which is a magneto-rheological fluid brake device.

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