Patent Application
20200332846
The present invention relates to an input device capable of varying rotational resistance by using magnetic viscous fluid.
An operation sensation imparting input device described in Japanese Unexamined Patent Application Publication No. 2010-211270 includes a rotary operation part; an encoder that detects a rotational state of the operation part; an armature rotor that rotates together with the operation part; an electromagnetic brake that applies rotational resistance to the operation part through the armature rotor; an electric motor that imparts autonomous rotation force to the operation part through a rotating shaft; and a controller that drives the electromagnetic brake and the electric motor. When rotational resistance is to be applied, the controller drives the electromagnetic brake to reduce power consumption. The controller is also capable of driving the electric motor to cause the operation part to rotate autonomously. The electromagnetic brake includes a winding disposed outside the electric motor so that the overall size of the device is reduced in a direction of a rotational axis.
The operation sensation imparting input device described in Japanese Unexamined Patent Application Publication No. 2010-211270 is structured such that the armature rotor is disposed between the electric motor and the operation part.
Therefore, reduction in the overall size in the direction of the rotational axis is limited by the sizes of these components.
The present invention provides an input device suitable for size reduction in a direction of a rotational axis of a rotating body.
An input device according to the present invention includes a fixed portion; a rotating body supported such that the rotating body is rotatable about a rotational axis; a rotation detection unit configured to detect a rotation of the rotating body; a brake applying unit configured to apply a braking force to the rotating body; and a torque applying unit configured to apply a driving torque for rotating the rotating body about the rotational axis to the rotating body. The brake applying unit includes a rotary plate rotatable together with the rotating body, magnetic viscous fluid disposed in a gap between the fixed portion and the rotary plate, and a brake applying coil configured to apply a magnetic field to the magnetic viscous fluid. The torque applying unit includes a stator and a rotor supported such that the rotor is rotatable with respect to the stator. One of the stator and the rotor of the torque applying unit includes a magnet and other of the stator and the rotor of the torque applying unit includes torque applying coils of at least two phases, the torque applying coils inducing magnetic fields for generating the driving torque applied to the rotating body. A controller is provided to control currents applied to the brake applying coil and the torque applying coils. The torque applying unit is disposed to surround an outer periphery of the brake applying unit.
Accordingly, size reduction in the direction of the rotational axis of the rotating body can be achieved. In addition, since the torque applying unit and the brake applying unit can be disposed close to each other, size reduction in a direction orthogonal to the rotational axis can also be achieved.
In the input device according to the present invention, preferably, the controller is capable of individually controlling a current applied to the brake applying coil and currents applied to the torque applying coils, and is capable of simultaneously generating the braking force and the driving torque.
In this case, various operation sensations can be provided to an operator.
In the input device according to the present invention, preferably, the rotor is supported such that the rotor is rotatable together with the rotating body, and includes an annular back yoke and a plurality of permanent magnets provided on an outer periphery of the back yoke and arranged such that poles of different polarities are alternately arranged in a circumferential direction of the back yoke, and the stator is disposed to surround a radially outer periphery of the rotor and face the permanent magnets, and includes coils formed of non-magnetic windings and a fixed member to which the coils are fixed, the coils serving as the torque applying coils.
In this case, magnetic cores having salient poles are not provided, and coils having no salient poles are used. Therefore, no cogging torque is generated in a rotating operation in which the coils are not energized. As a result, the operation sensations are not adversely affected by a cogging torque. In addition, when the fixed member of the stator is formed of a non-magnetic body, not only cogging due to variation in magnetic attraction force but also a rotational resistance due to a magnetic attraction force of a permanent magnet can be prevented.
In the input device according to the present invention, preferably, the torque applying coils include eight torque applying coils, and currents are applied to the torque applying coils such that adjacent ones of the torque applying coils generate magnetic fields in opposite directions. Two adjacent ones of the torque applying coils and two of the torque applying coils symmetric to the two adjacent ones of the torque applying coils about the rotational axis simultaneously receive currents in phase A, and remaining four of the torque applying coils simultaneously receive currents in phase B.
In this case, the curvature of the torque applying unit can be reduced, so that the torque applying unit can be easily manufactured. In addition, the area of the region in which the magnetic flux generated by the magnets extends through the torque applying coils can be increased without increasing the overall length in the direction of the rotational axis, and the driving torque can be increased accordingly.
In the input device according to the present invention, preferably, the brake applying unit includes a shaft portion configured to rotate together with the rotary plate, and the shaft portion is connected to the rotating body by a connecting member having spring characteristics.
In this case, a phase difference can be generated between the rotating operation of the shaft portion of the brake applying unit and the rotating operation of the rotating body. Therefore, even when the shaft portion of the brake applying unit is stopped in the end-stop state, if a low torque is applied to the rotating body, the shaft portion is twisted in response to the rotation of the rotating body. Accordingly, the rotation of the rotating body can be detected by the rotation detection unit, and a smooth operation sensation with small roughness can be provided to the operator by cancelling the end-stop state based on the result of the detection.
In the input device according to the present invention, preferably, the torque applying coils and the brake applying coil are arranged such that a center line of each of torque applying coils is orthogonal to a center line of the brake applying coil.
In this case, even when the torque applying coils and the brake applying coil are disposed close to each other, interference between the magnetic fields generated thereby can be reduced. Thus, the influence of the magnetic fields generated by the torque applying coils on the magnetic viscous fluid of the brake applying unit can be reduced.
According to the present invention, size reduction in the direction of the rotational axis of the rotating body can be achieved.
An input device according to an embodiment of the present invention will now be described in detail with reference to the drawings.
As illustrated in
As illustrated in
As illustrated in
The base plate 151 is substantially circular plate-shaped, and is fixed to the fixed portion 120 so that the central axis thereof coincides with the rotational axis AX. As illustrated in
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As illustrated in
The above-described eight air-core coils 153a, 153b, 153c, 153d, 153e, 153f, 153g, and 153h are provided on an inner peripheral surface 152a (see
As illustrated in
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As illustrated in
Referring to
Energization of the air-core coils 153a to 153h is controlled so that switching between the above-described two phases, that is, phase A and phase B, occurs every time the rotating body 130 rotates 120 degrees. Accordingly, switching between the states illustrated in
In the state illustrated in
The relationship between the currents applied to the air-core coils and the generated magnetic fields is similar in each of
The magnet unit 154 can be rotated or turned about the rotational axis AX with respect to the coil unit 153, which is fixed to the base plate 151, the fixed member 152, and the fixed portion 120, by applying currents to the air-core coils 153a to 153h in four patterns illustrated in
As illustrated in
As illustrated in
The rotation operation unit 300 is rotatably supported on the holder unit 220 by two radial bearings 351 and 551 and two pushers 352 and 552 (see
In the upper section 210A illustrated in
In the lower section 210B illustrated in
The holder unit 220 includes the annular member 270 that extends in both the upper section 210A and the lower section 210B. In the upper section 210A, the first yoke 230, the second yoke 240, and the third yoke 290 are formed separately. In the lower section 210B, the first yoke 430, the second yoke 440, and the third yoke 490 are formed separately. However, some of these yokes may instead be formed integrally with each other.
As illustrated in
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As illustrated in
The second surface 231d and the second surface 232d are arranged to extend parallel to each other and face each other in the radial direction at positions corresponding to each other in the first direction D1, thereby forming the third space 235 therebetween. The sealing member 260, which is composed of a non-magnetic body, is disposed in the third space 235, so that the second space 234 and the third space 235 form a magnetic gap.
The sealing member 260 has an annular shape and is made of a non-magnetic material, such as a synthetic resin. The sealing member 260 is formed by, for example, filling the third space 235 with a material in a fluid state and solidifying the material. Alternatively, an elastic material formed in an annular shape may be fitted into the third space 235. Alternatively, a non-elastic material may be formed into an annular shape and fixed with an adhesive. The sealing member 260 disposed in the third space 235 is substantially symmetrical about the central axis 211 (rotational axis).
A lower surface 231e of the inner yoke 231 and a lower surface 232e of the outer yoke 232 form a facing surface that faces the magnetic disc 320 (
The inner yoke 231 and the outer yoke 232 have substantially the same cross-sectional area along a plane orthogonal to the central axis 211 at the position where the first coil 250 is disposed. Accordingly, a magnetic field having an optimum structure can be realized until the saturation magnetic flux density is reached.
As illustrated in
As illustrated in
An upper surface 431e of the inner yoke 431 and an upper surface 432e of the outer yoke 432 form a facing surface that faces the magnetic disc 520 (
The inner yoke 431 and the outer yoke 432 have substantially the same cross-sectional area along a plane orthogonal to the central axis 211 at the position where the second coil 450 is disposed. Accordingly, a magnetic field having an optimum structure can be realized until the saturation magnetic flux density is reached.
As illustrated in
Accordingly, in the upper section 210A, the first surface 231c of the inner yoke 231 and the first surface 232c of the outer yoke 232 have different inclination angles with respect to the first direction D1, and the first surface 231c of the inner yoke 231 has a greater inclination angle. In other words, the first surface 231c of the inner yoke 231 has a smaller inclination angle with respect to the radial direction. Similarly, in the lower section 210B, the first surface 431c of the inner yoke 431 and the first surface 432c of the outer yoke 432 have different inclination angles with respect to the first direction D1, and the first surface 431c of the inner yoke 431 has a greater inclination angle. In other words, the first surface 431c of the inner yoke 431 has a smaller inclination angle with respect to the radial direction.
As illustrated in
The inner yoke 431 and the outer yoke 432 in the lower section 210B are also shaped such that the above-described center position 235x, which coincides with the center position of the third space 435 in the radial direction, is located outside the center of the overall body of the first yoke 430 in the radial direction. Accordingly, the upper surface 431e serving as a facing surface of the inner yoke 431 that faces the magnetic disc 520 and the upper surface 432e serving as a facing surface of the outer yoke 432 that faces the magnetic disc 520 have substantially the same area in plan view. Thus, the magnetic flux density in the region inside the magnetic gap and that in the region outside the magnetic gap are substantially equal to each other.
As illustrated in
As illustrated in
The shapes of the yokes 230, 240, 290, 430, 440, and 490 in plan view are not limited to circular shapes.
As illustrated in
The annular member 270 is disposed outside the first yoke 230 and the second yoke 240 in the radial direction in the upper section 210A, and outside the first yoke 430 and the second yoke 440 in the radial direction in the lower section 210B. The annular member 270 has an annular shape having an axis that coincides with the central axis 211, and is made of a non-magnetic material, such as a synthetic resin. The inner peripheral surface of the annular member 270 is shaped to extend along the first yoke 230 and the second yoke 240 in the upper section 210A and along the first yoke 430 and the second yoke 440 in the lower section 210B, and is fixed to the outer peripheral surface of each yoke. Accordingly, the first yoke 230 in the upper section 210A, the second yoke 240 in the upper section 210A, the second yoke 440 in the lower section 210B, and the first yoke 430 in the lower section 210B are arranged in that order in the first direction D1 and connected to each other by the annular member 270 that extends in the first direction D1. The gap 280 in the upper section 210A and the gap 480 in the lower section 210B are each closed by the annular member 270 in the radial direction.
As described above, the first yoke 230 and the second yoke 240 in the upper section 210A and the second yoke 440 and the first yoke 430 in the lower section 210B are arranged in that order and connected to each other by the annular member 270, and thus the holder unit 220 is integrally fixed. It is not necessary that the entire body of the annular member 270 be made of a non-magnetic material, and the annular member 270 may instead be made of a composite material including a non-magnetic portion that prevents magnetic short-circuiting between the first yoke 230 and the second yoke 240 in the upper section 210A and between the first yoke 430 and the second yoke 440 in the lower section 210B. Also in this case, the gap 280 and the gap 480 are preferably closed by the non-magnetic portion in the radial direction.
As illustrated in
In the upper section 210A, the inner yoke 231 and the outer yoke 232 of the first yoke 230 and the third yoke 290 are connected together, and the second yoke 240 is connected thereto with the magnetic disc 320 provided therebetween as described above, so that a closed-loop magnetic path (magnetic circuit) for a magnetic field generated by the first coil 250 is formed. Similarly, in the lower section 210B, the inner yoke 431 and the outer yoke 432 of the first yoke 430 and the third yoke 490 are connected together, and the second yoke 440 is connected thereto with the magnetic disc 520 provided therebetween as described above, so that a closed-loop magnetic path (magnetic circuit) for a magnetic field generated by the second coil 450 is formed.
When a current is applied to each of the two coils 250 and 450 in the above-described structure, magnetic fields are generated in directions schematically shown by the arrows in
In the example illustrated in
As illustrated in
The first yoke 230 in the upper section 210A has the second space 234 and the third space 235 that form a magnetic gap in the magnetic field having the above-described magnetic path. This magnetic gap is provided below the first coil 250 and between the first coil 250 and the gap 280 in which the magnetic disc 320 is disposed. The first coil 250 is spaced from the magnetic disc 320 and disposed in the first yoke 230, and the magnetic gap is formed in a portion of the space between the first coil 250 and the magnetic disc 320. Therefore, in the region around the magnetic gap, the magnetic flux of the magnetic field generated by the first coil 250 is restrained from extending through the first yoke 230 in the radial direction orthogonal to the central axis 211. In other words, in the space between the first coil 250 and the magnetic disc 320, the magnetic flux of the magnetic field generated by the first coil 250 can be directed toward the magnetic disc 320 along two inclined surfaces, which are the first surface 231c of the inner yoke 231 and the first surface 232c of the outer yoke 232. Accordingly, the magnetic flux that passes through the inner yoke 231 reliably extends downward toward the second yoke 240, and the magnetic flux that passes through the outer yoke 232 reliably extends upward in the direction from the second yoke 240 toward the third yoke 290.
The first yoke 430 in the lower section 210B also has the second space 434 and the third space 435 that form a magnetic gap. This magnetic gap is provided above the second coil 450 and between the second coil 450 and the gap 480 in which the magnetic disc 520 is disposed. The second coil 450 is spaced from the magnetic disc 520 and disposed in the first yoke 430, and the magnetic gap is formed in a portion of the space between the second coil 450 and the magnetic disc 520. Therefore, in the region around the magnetic gap, the magnetic flux of the magnetic field generated by the second coil 450 is restrained from extending through the first yoke 430 in the radial direction orthogonal to the central axis 211. In other words, in the space between the second coil 450 and the magnetic disc 520, the magnetic flux of the magnetic field generated by the second coil 450 can be directed toward the magnetic disc 520 along two inclined surfaces, which are the first surface 431c of the inner yoke 431 and the first surface 432c of the outer yoke 432. Accordingly, the magnetic flux that passes through the inner yoke 431 reliably extends upward toward the second yoke 440, and the magnetic flux that passes through the outer yoke 432 reliably extends downward in the direction from the second yoke 440 toward the third yoke 490.
The magnetic fields generated in the upper section 210A and the lower section 210B of the brake applying unit 210 are generated by the coils 250 and 450 wound around the central axis 211 that coincides with the rotational axis AX. In contrast, the magnetic fields generated in the torque applying unit 150 are generated by the air-core coils 153a to 153h wound around radial lines that are orthogonal to the rotational axis AX. Thus, the center line of the two coils 250 and 450 of the brake applying unit 210 may be orthogonal to the center lines of the air-core coils 153a to 153h of the torque applying unit 150, so that interference between the magnetic fields generated in the brake applying unit 210 and the magnetic fields generated in the torque applying unit 150 can be reduced.
As illustrated in
As illustrated in
The magnetic disc 320 in the upper section 210A has a center hole 321 that extends therethrough in the first direction D1 at the center of the circular flat surface. The magnetic disc 320 also has a plurality of through holes 322 that extend therethrough in the up-down direction at positions around the center hole 321. The magnetic disc 320 is fixed to the shaft 310 by inserting screws (only one of which is illustrated) through the through holes 322 in the first direction D1 and fitting shaft portions of the screws to the flange portion 312 of the shaft 310.
The magnetic disc 520 in the lower section 210B has a center hole 521 that extends therethrough in the first direction D1 at the center of the circular flat surface. The magnetic disc 520 also has a plurality of through holes 522 that extend therethrough in the up-down direction at positions around the center hole 521. The magnetic disc 520 is fixed to the shaft 310 by inserting screws (not illustrated) through the through holes 522 in the first direction D1 and fitting shaft portions of the screws to the flange portion 312 of the shaft 310.
As illustrated in
Accordingly, when the flange portion 312 is inserted through the hole 242 and the hole 442 while the second yoke 240 and the second yoke 440 are stacked together in the first direction D1, the flange portion 312 projects upward from the top surface 241 of the second yoke 240 so as to be in contact with the lower surface of the magnetic disc 320, and projects downward from the bottom surface 441 of the second yoke 440 so as to be in contact with the upper surface of the magnetic disc 520. The height of a portion of the gap 280 between the magnetic disc 320 and the second yoke 240 is determined by the amount by which the flange portion 312 projects from the second yoke 240, and the height of a portion of the gap 480 between the magnetic disc 520 and the second yoke 440 is determined by the amount by which the flange portion 312 projects from the second yoke 440.
As illustrated in
As illustrated in
As illustrated in
The magnetic flux extends downward from the inner yoke 231 of the first yoke 230 toward the second yoke 240 in a region closer to the central axis 211 than the four slits 323a, 323b, 323c, and 323d (inner region). In the region outside the four slits 323a, 323b, 323c, and 323d, the magnetic flux extends upward from the second yoke 240 toward the outer yoke 232 of the first yoke 230. The magnetic flux is restrained from passing through the four slits in the magnetic disc 320 in the radial direction. Since the four slits are provided at a position corresponding to the position of the third space 235, the second space 234, the third space 235, and the four slits 323a, 323b, 323c, and 323d are arranged in the first direction D1. Therefore, the magnetic field generated by the first coil 250 is reliably restrained from extending through the first yoke 230 or the magnetic disc 320 in the radial direction, and a stable magnetic circuit can be obtained.
As illustrated in
The magnetic flux mainly extends upward from the inner yoke 431 of the first yoke 430 toward the second yoke 440 in a region closer to the central axis 211 than the four slits 523a, 523b, 523c, and 523d (inner region). In the region outside the four slits 523a, 523b, 523c, and 523d, the magnetic flux mainly extends downward from the second yoke 440 toward the outer yoke 232 of the first yoke 430. Since the four slits are provided at a position corresponding to the position of the third space 435, the second space 434, the third space 435, and the four slits 523a, 523b, 523c, and 523d are arranged in the first direction D1. Therefore, the magnetic field generated by the second coil 450 is reliably restrained from extending through the first yoke 430 or the magnetic disc 520 in the radial direction, and a stable magnetic circuit can be obtained.
When the shaft 310 is rotated, the magnetic disc 320 rotates with respect to the first yoke 230 and the second yoke 240, and the magnetic disc 520 rotates with respect to the first yoke 430 and the second yoke 440. At this time, in the upper section 210A, the distance between the upper surface of the magnetic disc 320 and the bottom surface 236 of the first yoke 230 in the first direction D1 is maintained substantially constant, and the distance between the lower surface of the magnetic disc 320 and the top surface 241 of the second yoke 240 in the first direction D1 is maintained substantially constant. In addition, the distance between the outer peripheral surface of the magnetic disc 320 and the inner peripheral surface of the annular member 270 in the second direction D2 is also maintained substantially constant. Also in the lower section 210B, the distance between the lower surface of the magnetic disc 520 and the top surface 436 of the first yoke 430 in the first direction D1 is maintained substantially constant, and the distance between the upper surface of the magnetic disc 520 and the bottom surface 441 of the second yoke 440 in the first direction D1 is maintained substantially constant. In addition, the distance between the outer peripheral surface of the magnetic disc 520 and the inner peripheral surface of the annular member 270 in the second direction D2 is also maintained substantially constant.
As illustrated in
In the lower section 210B, a portion of the gap 480 between the bottom surface of the magnetic disc 520 and the top surface 436 of the first yoke 430 in the first direction D1 is filled with the magnetic viscous fluid 560, and a portion of the gap 480 between the upper surface of the magnetic disc 520 and the bottom surface 441 of the second yoke 440 in the first direction D1 is also filled with the magnetic viscous fluid 560. In addition, the above-described gap 481 between the outer peripheral surface of the magnetic disc 520 and the annular member 270 in the radial direction is also filled with the magnetic viscous fluid 560. The gap 480 around the magnetic disc 520 is sealed by components including the sealing member 460, the annular member 270, the shaft 310, the flange portion 312, the first yoke 430, and the second yoke 440. Therefore, the magnetic viscous fluid 560 is reliably retained in the gap 480.
The magnetic viscous fluids 360 and 560 are a substance whose viscosity varies when a magnetic field is applied thereto. The substance is, for example, a fluid obtained by dispersing particles of a magnetic material (magnetic particles) in non-magnetic liquid (solvent). The magnetic particles contained in the magnetic viscous fluids 360 and 560 are, for example, preferably iron-based particles containing carbon or ferrite particles. The iron-based particles containing carbon preferably have a carbon content of, for example, greater than or equal to 0.15%. The diameter of the magnetic particles is preferably greater than or equal to, for example, 0.5 μm, and more preferably greater than or equal to 1 μm. The solvent and magnetic particles of the magnetic viscous fluids 360 and 560 are preferably selected so that deposition of the magnetic particles due to gravity does not easily occur. In addition, the magnetic viscous fluids 360 and 560 preferably contain a coupling agent that prevents deposition of the magnetic particles.
When a current is applied to the first coil 250, the magnetic field illustrated in
In the lower section 210B, when a current is applied to the second coil 450, the magnetic field illustrated in
When no magnetic fields are generated by the coils 250 and 450, the magnetic particles contained in the magnetic viscous fluids 360 and 560 are dispersed in the solvent. Accordingly, when an operator operates and rotates the rotating body 130 and the operating force is transmitted from the connecting shaft portion 134 to the shaft portion 311, the rotation operation unit 300 is rotated with respect to the holder unit 220 without receiving a large resistance force. When the coils 250 and 450 are not energized but residual magnetic flux is present in the yokes, the shaft 310 receives a residual resistance torque based on the density of the residual magnetic flux.
When a current is applied to each of the coils 250 and 450 so that the magnetic fields are generated, the magnetic fields are applied to the magnetic viscous fluids 360 and 560 in the first direction D1. Due to the magnetic fields, the magnetic particles dispersed in the magnetic viscous fluids 360 and 560 accumulate along the lines of magnetic force, and the magnetic particles arranged in the first direction D1 are magnetically connected to each other. In this state, when a force for rotating the shaft 310 around the central axis 211 is applied in a rotating operation of the rotating body 130, a resistance force (braking torque) generated by the magnetic particles connected to each other serves as a braking force. Therefore, the operator feels a greater resistance force than when no magnetic fields are generated.
Since the magnetic discs 320 and 520 having the shape of a circular plate that extends radially outward from the shaft 310 are used, the magnetic viscous fluids 360 and 560 can be provided over a larger area than when only the shaft 310 is provided. The magnitude of the resistance force generated by the magnetic viscous fluid 360 correlates with the area over which the magnetic viscous fluid 360 that receives the magnetic field in the up-down direction is provided between the bottom surface 236 of the first yoke 230 and the top surface 241 of the second yoke 240 in the up-down direction. The magnitude of the resistance force generated by the magnetic viscous fluid 560 correlates with the area over which the magnetic viscous fluid 560 that receives the magnetic field in the up-down direction is provided between the top surface 436 of the first yoke 430 and the bottom surface 441 of the second yoke 440 in the up-down direction. In particular, the magnitude of the resistance force generated by the magnetic viscous fluids 360 and 560 when the shaft 310 is operated such that the magnetic discs 320 and 520 are rotated correlates with the areas over which the magnetic viscous fluids 360 and 560 are provided along planes orthogonal to the rotation direction of the magnetic discs 320 and 520. The control range of the resistance force (braking torque) can be increased by increasing the area over which the magnetic viscous fluids 360 and 560 to which the magnetic fields can be applied are provided.
In the upper section 210A, the first yoke 230 is constituted by the inner yoke 231 and the outer yoke 232 so that the magnetic gap is formed in a portion of the space between the first coil 250 and the magnetic disc 320. Accordingly, the areas of the lower surface 231e of the inner yoke 231 and the lower surface 232e of the outer yoke 232 through which the magnetic flux passes are increased without increasing the outer diameter. In addition, in the lower section 210B, the first yoke 430 is constituted by the inner yoke 431 and the outer yoke 432 so that the magnetic gap is formed in a portion of the space between the second coil 450 and the magnetic disc 520. Accordingly, the areas of the upper surface 431e of the inner yoke 431 and the upper surface 432e of the outer yoke 432 through which the magnetic flux passes are increased without increasing the outer diameter. Furthermore, the magnetic flux having a magnetic field component that mainly extends in the first direction D1 can be caused to pass through the magnetic discs 320 and 520 over large areas, and the resistance force (braking torque) can be generated in a direction based on the direction of the magnetic flux. Therefore, a large shear stress can be generated without increasing the size of the device.
As illustrated in
As illustrated in
The connecting member 135 may be fixed to the connecting shaft portion 134 and the shaft portion 311, which are connected to each other, so as to externally cover the connecting shaft portion 134 and the shaft portion 311 (
As illustrated in
The encoder disc 141 forms the rotation detection unit 140 together with a detection substrate 142 and a detecting element 143. The encoder disc 141 has reflective and non-reflective portions that are alternately arranged in the circumferential direction thereof. When the rotating body 130 rotates about the rotational axis AX, the encoder disc 141 rotates about the rotational axis AX together with the rotating body 130.
As illustrated in
The detecting element 143 includes a light emitting element and a light receiving element. The light emitting element emits detection light toward the encoder disc 141 in a predetermined area. The light receiving element receives light reflected by the reflective portions of the encoder disc 141, and the rotation angle of the encoder disc 141 and the rotating body 130 on which the encoder disc 141 is provided is detected based on the result of the light receiving process. The result of the detection is output to the controller 160 (
The controller 160 supplies currents controlled based on the detection result obtained by the detecting element 143 to the air-core coils 153a to 153h (torque applying coils) of the coil unit 153 and the two coils 250 and 450 (brake applying coils) of the brake applying unit 210. The controller 160 may be capable of individually controlling application of current to the torque applying coils and application of current to the brake applying coils. The controller 160 is also capable of individually controlling the currents applied to the air-core coils 153a to 153h and the currents applied to the two coils 250 and 450 of the brake applying unit 210. The controller 160 is also capable of causing the torque applying unit 150 to generate a driving torque and the brake applying unit 210 to generate a braking force simultaneously or at different times. The above-described current control enables the torque applying coils to generate the driving torque and the brake applying unit to generate the braking force at any timing. Accordingly, various operation sensations can be provided to the user.
According to the above-described structure, when the torque applying unit 150 is driven, the magnet unit 154 and the back yoke 155, which are integrated with each other, are rotated or turned about the rotational axis AX due to the magnetic fields induced by the air-core coils 153a to 153h, which serve as torque applying coils. Accordingly, the rotating body 130, which is fixed to the back yoke 155, receives a driving torque around the rotational axis AX.
More specifically, when currents are applied to each of the air-core coils 153a to 153h in four patterns illustrated in
The direction of the driving torque is controlled based on the directions in which the currents are applied in the four patterns illustrated in
When magnetic cores or magnetic salient poles that face the magnets are provided as in an ordinary motor, a magnetic attraction force is applied between the magnets and the magnetic bodies, and a cogging torque, which is a torque variation based on a magnetic circuit, is generated even in a rotating operation in which the coils are not energized.
In contrast, the input device 110 of the present embodiment is structured such that magnetic cores having salient poles are not provided and that the air-core coils having no salient poles are used. Therefore, no cogging torque is generated in a rotating operation in which the coils are not energized.
In addition, according to the present embodiment, the air-core coils 153a to 153h are held by the fixed member 152 composed of a non-magnetic body. Therefore, the magnetic attraction force between the magnets and the magnetic bodies may be set to 0. Thus, the rotating operation in which the air-core coils 153a to 153h are not energized can be performed in a state close to an ideal state, that is, a so-called torque-free state.
The combination of the number of air-core coils included in the coil unit 153 and the number of magnets included in the magnet unit 154 is not limited to that in the present embodiment. In addition, the air-core coils may be replaced by, for example, coils formed by winding wires around non-magnetic cores as long as an equivalent magnetic circuit can be obtained.
The rotating body 130 receives a braking force from the brake applying unit 210 through the connecting shaft portion 134. The brake applying unit 210 will now be described.
As illustrated in
When the controller 160 applies currents to the two coils 250 and 450, which serve as brake applying coils, the above-described magnetic fields are generated and magnetic flux passes through each of the magnetic discs 320 and 520 in the up-down direction. The density of magnetic flux extending in the radial direction is very low in the magnetic discs 320 and 520.
When no magnetic field is generated by the coils 250 and 450, the magnetic particles contained in the magnetic viscous fluids 360 and 560 are dispersed in the solvent. Therefore, the connecting shaft portion 134 connected to the shaft portion 311 hardly receives a braking force. Therefore, the operator can operate and rotate the rotating body 130 without receiving a large braking force from the brake applying unit 210.
When a current is applied to each of the coils 250 and 450, which serve as brake applying coils, so that the magnetic fields are generated, the magnetic fields are applied to the magnetic viscous fluids 360 and 560 in the up-down direction. Due to the magnetic fields, the magnetic particles dispersed in the magnetic viscous fluids 360 and 560 accumulate along the lines of magnetic force, and the magnetic particles arranged in the up-down direction are magnetically connected to each other. When the rotating body 130 is operated and rotated in this state, a resistance force (braking torque) generated by the magnetic particles connected to each other is applied to the shaft portion 311. Accordingly, a braking force is transmitted from the shaft portion 311 to the rotating body 130 through the connecting shaft portion 134, which is connected to the shaft portion 311. Therefore, the operator feels a greater resistance force than when no magnetic fields are generated. When the currents applied to the first coils 250 and 450 are controlled to vary the intensities of the magnetic fields, the resistance force felt by the operator can be increased or reduced, so that the operation sensation provided to the operator can be varied. Thus, not only variable control of the driving torque applied by the torque applying unit 150 but also variable control of the braking force of a desired magnitude can be achieved, so that various operation sensations can be provided to the operator that operates the rotating body 130.
The controller 160 applies predetermined currents to the two coils 250 and 450, which serve as brake applying coils, when the rotation angle detected by the detecting element 143 reaches a predetermined angle set in advance. Accordingly, the shaft portion 311 applies a strong braking force to the rotating body 130 through the connecting shaft portion 134, so that the operator that operates the rotating body 130 feels an operation sensation as if the rotating body 130 has been stopped by an imaginary stopper (end-stop state).
When the rotating body 130 is operated and rotated in the reverse direction while the rotation of the shaft portion 311 of the brake applying unit 210 is stopped in the end-stop state, the central spring portion 135a of the connecting member 135 fixed to the connecting shaft portion 134 and the shaft portion 311 is twisted. When the shaft portion 311 is twisted by the elastic force of the central spring portion 135a, the rotation of the rotating body 130 can be detected by the rotation detection unit 140, and the end-stop state is canceled based on the result of the detection. Accordingly, a smooth operation sensation with small roughness can be provided to the operator.
The above-described input device 110 has the following effects.
(1) Since the torque applying unit 150 is disposed to surround the outer periphery of the brake applying unit 210, size reduction in the direction of the rotational axis AX of the rotating body 130 can be achieved. In addition, since the torque applying unit 150 and the brake applying unit 210 can be disposed close to each other, size reduction in the direction orthogonal to the rotational axis AX can also be achieved.
(2) Since the currents applied to the two coils 250 and 450, which serve as brake applying coils, and the currents applied to the air-core coils 153a to 153h, which serve as torque applying coils, can be individually controlled by the controller 160, and since the braking force and the driving torque can be generated simultaneously, various operation sensations can be provided to the operator.
(3) The torque applying unit 150 includes the rotor that is supported such that the rotor is rotatable together with the rotating body 130 and the stator disposed to surround the radially outer periphery of the rotor. The rotor includes the annular back yoke 155 and the magnets 154a to 154f, which are provided on the outer periphery of the back yoke 155 and arranged such that poles of different polarities are alternately arranged in the circumferential direction of the back yoke 155. The stator is disposed to face the magnets 154a to 154f and includes the air-core coils 153a to 153h, which serve as torque applying coils and which are formed of non-magnetic windings, and the fixed member 152, to which the air-core coils 153a to 153h are fixed. Since magnetic cores having salient poles are not provided and the air-core coils 153a to 153h having no salient poles are used, no cogging torque is generated in a rotating operation in which the air-core coils 153a to 153h are not energized. Therefore, the operation sensations are not adversely affected by a cogging torque. In addition, since the fixed member 152 of the stator is formed of a non-magnetic body, not only cogging due to variation in magnetic attraction force but also a rotational resistance due to a magnetic attraction force of a permanent magnet can be prevented.
(4) The air-core coils 153a to 153h are provided as torque applying coils, and currents are applied thereto so that adjacent air-core coils generate magnetic fields in the opposite directions. The air-core coils 153a to 153h are energized such that two adjacent coils and other two coils that are symmetric to the two adjacent coils about the rotational axis AX simultaneously receive currents in phase A, and that the remaining four coils simultaneously receive currents in phase B. Accordingly, the curvature of the torque applying unit 150 can be reduced, so that the torque applying unit 150 can be easily manufactured. In addition, the area of the region in which the magnetic flux generated by the magnets 154a to 154f extends through the air-core coils 153a to 153h can be increased without increasing the overall length in the direction of the rotational axis AX, and the driving torque can be increased accordingly.
(5) The connecting shaft portion 134 that extends from the rotating body 130 and the shaft portion 311 that extends from the brake applying unit 210 are connected to each other with the connecting member 135 having spring characteristics. Accordingly, a phase difference can be generated between the rotating operation of the shaft portion 311 of the brake applying unit 210 and the rotating operation of the rotating body 130. Therefore, even when the shaft portion 311 of the brake applying unit 210 is stopped in the end-stop state, if a low torque is applied to the rotating body 130, the shaft portion 311 is twisted in response to the rotation of the rotating body 130. Accordingly, the rotation of the rotating body 130 can be detected by the rotation detection unit 140, and a smooth operation sensation with small roughness can be provided to the operator by cancelling the end-stop state based on the result of the detection.
(6) The coil unit 153, which serves as torque applying coils, and the two coils 250 and 450, which serve as brake applying coils, have center lines that are orthogonal to each other. Therefore, even when the torque applying coils and the brake applying coils are disposed close to each other, interference between the magnetic fields generated thereby can be reduced. Accordingly, the influence of the magnetic fields generated by the torque applying coils on the magnetic viscous fluids 360 and 560 of the brake applying unit 210 can be reduced.
Although the present invention has been described with reference to the embodiment, the present invention is not limited to the above-described embodiment, and improvements and modifications can be made for improvement purposes or within the spirit of the present invention.
As described above, the input device according to the present invention is useful in that the size thereof in the direction of the rotational axis can be reduced.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-009610 | Jan 2018 | JP | national |
This application is a Continuation of International Application No. PCT/JP2018/048207 filed on Dec. 27, 2018, which claims benefit of Japanese Patent Application No. 2018-009610 filed on Jan. 24, 2018. The entire contents of each application noted above are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2018/048207 | Dec 2018 | US |
| Child | 16916211 | US |
