JP2023154817A - Rotation transmission device, and steer-by-wire type steering device using the same - Google Patents

Abstract

To provide a rotation transmission device mounted with an electromagnet, with electric redundancy.SOLUTION: In a rotation transmission device incorporated in a steer-by-wire type steering device as a brake unit 7, two power source systems are provided to energize an electromagnet 52, and a solenoid coil 58 wound on a feed core 57 of the electromagnet 52 is formed by two wires respectively connected to power source lines 71a, 71b of each of the power source systems. In a normal time, a first power source system is used, and in a case when electric failure occurs in the first power source system during energization to the electromagnet 52 from the power source line 71a of the first power source system, the electromagnet 52 is energized by the power source line 71b of a second power source system so as to keep a function as the brake unit 7.SELECTED DRAWING: Figure 2

Description

The present invention relates to a rotation transmission device that switches between transmitting and cutting off rotational torque from a rotationally driven input-side member to an output-side member by controlling energization of an electromagnet, and a steer-by-wire steering system using the same.

2. Description of the Related Art A steer-by-wire type steering device is known as a steering device that changes the direction of a steering section such as a steering wheel (generally a front wheel) of a vehicle or a rudder of a ship in response to a rotational operation of a steering wheel by a driver.

A steer-by-wire steering system includes a steering sensor that detects the amount of operation of a steering wheel, and a steering actuator that is mechanically separated from the steering wheel. The steering actuator operates according to the amount of operation of the steering wheel detected by the steering sensor, and changes the direction of the steering section.

This type of steer-by-wire steering device can once convert the amount of operation of a steering wheel by a driver into an electrical signal, and can control the operation of a steering actuator based on the electrical signal. For this reason, for example, the amount of change in the direction of the steering section when the steering wheel is operated is adjusted according to the moving speed of the vehicle, ship, etc. It is possible to optimize the correspondence between the operation amount and the operation amount of the steering actuator.

On the other hand, in a steer-by-wire steering system, the steering wheel, which is rotated by the driver, and the steering actuator, which changes the direction of the steering section, are mechanically separated, so the direction of the steering section is fixed. Even when the travel limit (stroke end) is reached, the driver may further rotate the steering wheel. Therefore, a steer-by-wire steering system for a vehicle has been proposed that allows the driver to sense the situation through the steering wheel when the direction of the steering section reaches the stroke end (see Patent Document 1). .

The steer-by-wire steering system for a vehicle disclosed in Patent Document 1 includes a reaction force motor that applies a steering reaction force to the steering wheel that is calculated based on the vehicle speed, the amount of operation of the steering wheel, etc., and a reaction force motor that controls the reaction force motor. and a force controller. Then, the reaction force controller performs control to correct and increase the magnitude of the steering reaction force generated by the reaction force motor when the direction of the steered wheels reaches the stroke end. Thereby, the driver can sense through the steering wheel that the direction of the steered wheels has reached the stroke end.

However, when such control is performed, the control of the reaction force motor becomes complicated, and since the steering reaction force of the steering wheel only increases and does not prevent the rotation of the steering wheel, Some drivers may not notice that the direction of the steered wheels has reached the stroke end and may continue to rotate the steering wheel.

In contrast, when the direction of the steering section has not reached the stroke end, the steering wheel can be rotated (steering operation is possible), and when the direction of the steering section has reached the stroke end, the steering wheel can be rotated. It is sufficient to incorporate a mechanism that physically prevents rotation (steering lock).

As one of the mechanisms described above, there is an engaged state in which the rotational torque can be transmitted from the rotationally driven input side member to the output side member, and a disengaged state in which the transmission of the rotational torque is interrupted. It is conceivable to use a rotation transmission device that performs the switching by controlling the energization of the electromagnet. That is, the rotation transmission device is installed so that the shaft that rotates integrally with the steering wheel becomes the input side member, and the stationary member that is stationary with respect to the input side member becomes the output side member, so that the direction of the steering part is at the end of the stroke. When the direction of the steering section reaches the stroke end, the shaft and the stationary member are disengaged by stopping the power supply to the electromagnet, and the shaft and steering wheel are allowed to rotate. When the direction of the steering section reaches the stroke end, the electromagnet A mechanism can be constructed in which the shaft and the stationary member are brought into engagement by energization, thereby rendering the shaft and the steering wheel unrotatable.

International Publication No. 2020/195226

However, in a steer-by-wire steering system that incorporates the rotation transmission device as described above, if an electrical defect occurs in the solenoid coil of the electromagnet installed in the rotation transmission device, the direction of the steering section may reach the stroke end. Even if the steering wheel is turned on, the electromagnet is de-energized and the steering wheel becomes rotatable (steering free state), causing the driver to rotate the steering wheel beyond the steering limit.

This problem of malfunctions due to electrical defects in the solenoid coils of the electromagnets is not limited to steer-by-wire steering devices, but is common to mechanical devices incorporating rotation transmission devices such as those described above.

Therefore, the first object of the present invention is to provide electrical redundancy to a rotation transmission device equipped with an electromagnet, and provides a steer-by-wire steering system incorporating a rotation transmission device having electrical redundancy. This is the second issue.

In order to solve the above first problem, the present invention includes an input side member and an output side member that are rotationally driven, and is capable of transmitting rotational torque from the input side member to the output side member. In a rotation transmission device that switches between an engaged state and a disengaged state in which transmission of the rotational torque is cut off by controlling energization to an electromagnet, a plurality of power supply systems for energizing the electromagnet are provided, one of which is When the first power system is used in normal times and an electrical failure occurs in the first power system while power is being supplied from the first power system to the electromagnet, the electromagnet is connected to the electromagnet from another power system. A configuration was adopted in which energization is carried out.

Here, when the electromagnet is composed of an annular field core and a solenoid coil wound around the field core, a plurality of wires forming the solenoid coil and connected to each of the power supply systems respectively It is possible to adopt a configuration in which the wires are wound at the same time (they are wound in a spiral shape alternately along the winding direction).

When winding multiple wires at the same time as described above, if the number of turns of the multiple wires is the same, the electromagnet will be able to attract the same amount of energy before and after the occurrence of an electrical failure in the first power supply system. The power can be secured and the function of the rotation transmission device can be prevented from changing.

On the other hand, the number of turns of the wire connected to a power supply system other than the first power supply system may be smaller than the number of turns of the wire connected to the first power supply system, thereby reducing the size of the electromagnet. can. In that case, the electromagnet should be designed to have the minimum necessary adsorption force after an electrical failure occurs in the first power supply system.

Further, in order to solve the second problem, the present invention includes a steering wheel, a steering sensor that detects the amount of operation of the steering wheel, and a steering wheel that rotates according to the amount of operation of the steering wheel detected by the steering sensor. In a steer-by-wire steering device comprising a steering actuator that changes the direction of a rudder, and a shaft connected to the steering wheel so as to rotate together with the steering wheel, the rotation transmission device configured as described above, The shaft is the input side member, and a stationary member that is stationary with respect to the input side member is incorporated as the output side member, and when the direction of the steering section has not reached its movement limit, the By stopping the power supply to the electromagnet from the first power supply system or another power supply system, the shaft and the stationary member are disengaged, and the shaft and the steering wheel can be rotated, and the steering unit is rotated. When the direction reaches its movement limit, the shaft and the stationary member are brought into engagement by energizing the electromagnet, so that the shaft and the steering wheel cannot rotate.

As mentioned above, the rotation transmission device of the present invention has electrical redundancy by providing multiple power supply systems for energizing the electromagnets, so even if an electrical failure occurs, the electromagnets will not be damaged. The function of switching between transmission and cutoff of rotational torque from the input side member to the output side member can be maintained by controlling the current flow.

Further, the steer-by-wire steering system of the present invention incorporates the rotation transmission device having electrical redundancy as described above, and when the electromagnet is de-energized, the steering wheel becomes rotatable (steering-free state); Since the steering wheel is in a non-rotatable state (steering locked state), even if an electrical failure occurs while the electromagnet is energized, the steering locked state can be maintained.

A diagram schematically showing a steer-by-wire steering device incorporating a rotation transmission device according to an embodiment of the present invention as a brake unit. Cross-sectional view near the brake unit in Figure 1 Cross-sectional view along line III-III in Figure 2 Exploded perspective view of main parts in Figure 2 Cross-sectional view taken along line V-V in Figure 2 Enlarged view near the armature in Figure 2 View from arrow A direction in Figure 2 A diagram schematically showing how to wind the solenoid coil of the electromagnet in Figure 2.

Embodiments of the present invention will be described below based on FIGS. 1 to 8. FIG. 1 shows a steer-by-wire steering system (hereinafter simply referred to as "steering system") in which a rotation transmission device according to an embodiment of the present invention is incorporated as a brake unit 7. This steering device converts the amount of operation of the steering wheel 1 by the driver into an electrical signal, and controls the steering actuator 2 based on the electrical signal to direct the pair of left and right steered wheels 3 as a steering unit. It is something that can change.

This steering device includes a steering wheel 1 that is steered by a driver, a shaft 4 connected to the steering wheel 1, a steering sensor 5 that detects the amount of operation of the steering wheel 1, and a steering reaction force that applies a steering reaction force to the steering wheel 1. a reaction force motor 6; a brake unit (rotation transmission device) 7 that switches between a state in which rotation of the steering wheel 1 is allowed (steering free state) and a state in which rotation of the steering wheel 1 is prevented (steering lock state); It includes a steering actuator 2 that is mechanically separated from the steering wheel 1 and a control section 8 .

The shaft 4 is connected to the steering wheel 1 so as to rotate together with the steering wheel 1 when the steering wheel 1 is steered. Steering sensor 5 is attached to shaft 4 . Examples of the steering sensor 5 include a steering angle sensor that detects the steering angle of the steering wheel 1, a steering torque sensor that detects the steering torque input to the steering wheel 1 by the driver, and the like.

The reaction motor 6 is an electric motor that generates rotational torque when energized. The reaction motor 6 is connected to the end of the shaft 4. The reaction force motor 6 applies a steering reaction force to the steering wheel 1 via the shaft 4 by inputting rotational torque to the shaft 4 .

The steering actuator 2 includes a steering shaft 10, a steering shaft housing 11, a steering motor 12 that moves the steering shaft 10 in the left-right direction of the vehicle, and a steering sensor 13 that detects the position of the steering shaft 10. and has. The steered shaft 10 is supported by a steered shaft housing 11 so as to be movable in the left-right direction of the vehicle. The steered shaft housing 11 accommodates the center portion of the steered shaft 10 such that both left and right ends of the steered shaft 10 protrude from the steered shaft housing 11.

The steering motor 12 and the steering sensor 13 are attached to the steering shaft housing 11. A motion conversion mechanism (not shown) that converts the rotation output by the steering motor 12 into linear motion of the steering shaft 10 is installed between the steering motor 12 and the steering shaft 10 . Both left and right ends of the steered shaft 10 are connected to a pair of left and right steered wheels 3 via tie rods 14, and when the steered shaft 10 moves in the axial direction, the orientation of the pair of left and right steered wheels 3 changes in conjunction with this movement. It looks like this.

As shown in FIG. 2, the reaction motor 6 includes a motor case 15 and a motor shaft 16 that protrudes from the motor case 15 on the side opposite to the steering wheel 1 (lower side in the figure). The motor shaft 16 is rotatably supported by a rolling bearing (not shown) built into the motor case 15 . Further, the motor shaft 16 is a component of the shaft 4, and is connected to a shaft portion of the shaft 4 on the steering column side so as to rotate together with the steering wheel 1. The motor case 15 is fixed to a vehicle body (not shown) so as not to rotate.

The brake unit 7 has an input-side member and an output-side member that are rotationally driven, and is in an engaged state in which rotational torque can be transmitted from the input-side member to the output-side member, and in an engaged state in which transmission of rotational torque is interrupted. Using a rotation transmission device configured to switch between the disengaged state and the disengaged state by controlling the energization of the electromagnet, the shaft 4 connected to the steering wheel 1 is used as the input side member, and the stationary member stationary with respect to the shaft 4 is used as the output side. By incorporating it as a member, it has a function as a brake.

Specifically, the brake unit 7 includes an inner ring 20 connected to a motor shaft 16 that is a component of the shaft 4, an outer ring 21 having an inner periphery disposed around the inner ring 20, and an outer ring 21 formed on the outer periphery of the inner ring 20. a plurality of cam surfaces 22 (see FIG. 3), a cylindrical surface 23 formed on the inner periphery of the outer ring 21, an engager 24 disposed between each cam surface 22 and the cylindrical surface 23, A retainer 25 that holds the goggles 24, a centering spring 26 that is prevented from rotating by the inner ring 20 and the retainer 25, and an excitation-operated electromagnetic brake (hereinafter simply referred to as "electromagnetic brake") 27 that brakes the retainer 25. , and a brake case 28 that is a stationary member connected to the motor case 15 and stationary with respect to the shaft 4.

The inner ring 20 shown in FIGS. 2 and 3 is a component of the shaft 4 and is spline-fitted to the outer periphery of the motor shaft 16. By this spline fitting, the motor shaft 16 is connected to the inner ring 20 without any play so that it does not rotate relative to the inner ring 20 at all.

Note that the entire inner ring 20 is integrally formed by forging. The reason why the inner ring 20 and the motor shaft 16 are made separate is that it becomes easy to form the plurality of cam surfaces 22 with high precision by forging. The shaft 4 may be configured by connecting a plurality of members such as an inner ring 20, a motor shaft 16, and a steering shaft directly connected to the steering wheel 1, as shown in FIGS. It may be constructed of a single member or a plurality of members as appropriate, such as by integrally forming the motor shaft or by integrally forming the motor shaft and the inner ring.

The outer ring 21 and the brake case 28 shown in FIG. 2 are formed separately from each other. The brake case 28 is a cylindrical member that collectively accommodates the constituent members of the brake unit 7 (inner ring 20, engagement element 24, retainer 25, electromagnetic brake 27, etc.). The brake case 28 is made of a non-magnetic material (aluminum alloy, copper, etc.). A flange portion extending radially outward is formed at one axial end of the brake case 28, and the flange portion is fixed to the axial end surface of the motor case 15 with bolts (not shown).

On the other hand, the outer ring 21 is made of steel. The outer ring 21 is fitted into a cylindrical brake case 28, and is prevented from coming off from the brake case 28 by a retaining ring 29 attached to the inner circumference of the brake case 28. A bearing 30 that rotatably supports the inner ring 20 is arranged between the inner periphery of the outer ring 21 and the outer periphery of the inner ring 20.

As shown in FIGS. 2 and 3, a common key member 33 is fitted into a key groove 31 formed on the inner periphery of the brake case 28 and a key groove 32 formed on the outer periphery of the outer ring 21. 33 prevents the outer ring 21 from rotating on the brake case 28.

A cam surface 22 on the outer circumference of the inner ring 20 shown in FIG. 3 faces a cylindrical surface 23 on the inner circumference of the outer ring 21 in the radial direction. A wedge space is formed between the cam surface 22 and the cylindrical surface 23, which becomes gradually narrower from the center in the circumferential direction toward both ends in the circumferential direction.

As shown in FIGS. 3 and 4, the retainer 25 is an annular member in which a plurality of pockets 34 penetrating in the radial direction are formed at intervals in the circumferential direction. An engaging element 24 is accommodated in each pocket 34.

As shown in FIG. 2, the retainer 25 has an inward flange portion 35. As shown in FIG. The flange portion 35 is located between a retaining ring 36 attached to the outer circumference of the inner ring 20 and a shoulder portion 37 formed on the outer circumference of the inner ring 20. The flange portion 35, the retaining ring 36, and the shoulder portion 37 restrict the axial movement of the retainer 25.

The engager 24 is composed of a roller having a circular rolling surface that rotates around the center axis of the engager.

The retainer 25 has an engagement position where the engager 24 is engaged with the cam surface 22 and the cylindrical surface 23 by moving the engager 24 in the circumferential direction from the circumferential center of the cam surface 22, as shown in FIG. 24 to the circumferential center of the cam surface 22 to disengage the engagement of the engager 24 from the cam surface 22 and the cylindrical surface 23. has been done.

The centering spring 26 is an elastic member that elastically holds the retainer 25 in the released position and transmits the rotational force of the shaft 4 to the retainer 25. As shown in FIG. 3, the centering spring 26 includes a C-shaped annular portion 38 made of steel wire wound in a C-shape, and a pair of extension portions 39 extending radially outward from both ends of the C-shaped annular portion 38. It consists of

A recess 40 and a radial groove 41 for holding the centering spring 26 are formed in the axial end surface of the inner ring 20 . The recess 40 has a circular arc groove shape extending along the circumferential direction. The radial groove 41 penetrates outward in the radial direction from the recess 40 to the outer circumference of the inner ring 20 .

The C-shaped annular portion 38 of the centering spring 26 is fitted into the recess 40. The pair of extensions 39 are inserted into the radial groove 41 . Further, the extending portion 39 protrudes from the radially outer end of the radial groove 41, and the protruding portion of the extending portion 39 from the radial groove 41 is inserted into the retainer groove 42 formed in the retainer 25. It has been inserted. The radial groove 41 and the cage groove 42 are formed to have the same circumferential width. The extending portion 39 is in contact with the groove inner surface at both circumferential ends of the radial groove 41 and the groove inner surface at both circumferential ends of the retainer groove 42 . As a result, the centering spring 26 is prevented from rotating by the inner ring 20 so as to rotate together with the inner ring 20, and is also prevented from rotating by the retainer 25, and the centering spring 26 is prevented from rotating by the retainer 25, and the centering spring 26 is prevented from rotating by the retainer 25. The retainer 25 can be held elastically in the released position by the circumferential force that is applied.

As shown in FIGS. 5 and 6, the centering spring 26 is pulled out of the recess 40 and the radial groove 41 by an annular intermediate plate 43 that is fitted onto the outer periphery of the inner ring 20 and constitutes the electromagnetic brake 27 as described later. It is regulated in the axial direction so that it does not occur. The axial movement of the intermediate plate 43 is restricted by a retaining ring 44 attached to the outer periphery of the inner ring 20 and the axial end surface of the inner ring 20.

As shown in FIGS. 2 and 6, the electromagnetic brake 27 includes the intermediate plate 43, an electromagnet 52 fixed to the brake case 28, an armature 53 facing the electromagnet 52 in the axial direction, and the armature 53 connected to the electromagnet 52. It has a separation spring 54 that urges in the direction of separation.

As shown in FIGS. 4 to 6, the intermediate plate 43 is prevented from rotating by the retainer 25 by engagement between an engaging protrusion 49 formed on its outer periphery and an engaging recess 55 formed in the retainer 25. ing. Further, an axial protrusion 50 that extends in the axial direction toward the armature 53 is formed on the outer circumference of the intermediate plate 43, and the axial protrusion 50 is inserted into an axial hole 51 formed in the armature 53. Due to the engagement, the intermediate plate 43 is prevented from rotating while being movable in the axial direction relative to the armature 41.

As shown in FIGS. 2 and 6, the electromagnet 52 has an annular field core 57 with a C-shaped cross section that opens in the axial direction toward the armature 53, and a solenoid coil 58 wound around the field core 57. . The electromagnet 52 is attached to the inside of the brake case 28 so as not to move in either the axial direction or the circumferential direction, and serves as a stationary part that remains stationary with respect to the inner ring 20. A retaining ring 59 is attached to the inner periphery of the brake case 28 to restrict movement of the electromagnet 52 in the axial direction.

Further, the electromagnet 52 is configured to be energized from two power supply systems. That is, as shown in FIGS. 2 and 7, power lines 71a and 71b of two power supply systems that supply power to the solenoid coil 58 of the electromagnet 52 are connected to the through hole 70 formed on the other end surface of the brake case 28. A rubber grommet 72 is attached to fill the gap between each power supply wire 71a, 71b and the inner periphery of the through hole 70. As shown in FIG. 8, the solenoid coil 58 is formed of two wires 73a and 73b that are simultaneously wound around the field core 57 with the same number of turns, and each wire 73a and 73b is a power line of a power supply system. 71a and 71b. Then, the first power supply system of the two power supply systems is used during normal times, and an electrical failure occurs in the first power supply system while power is being supplied from the power line 71a of the first power supply system to the electromagnet 52. In this case, the electromagnet 52 is energized from the power line 71b of the second power supply system. Thereby, this brake unit 7 has electrical redundancy.

The armature 53 is movable in the axial direction by the outer circumference of the inner ring shaft 60 between the inner ring shaft 60 provided integrally with the inner ring 20 and the inner periphery of the brake case 28 and between the intermediate plate 43 and the electromagnet 52. Supported. The armature 53 is a disc-shaped member made of a magnetic material (iron, silicon steel, etc.). Note that a bearing that rotatably supports the inner ring 20 is arranged between the inner ring shaft portion 60 and the inner periphery of the brake case 28.

The separation spring 54 is made of an annular spring such as a wave washer, and is arranged between the end surface of the armature 53 on the side opposite to the intermediate plate 43 and the end surface of the field core 57 of the electromagnet 52, as shown in FIG. When the electromagnet 52 is in a non-excited state in which no current is applied, the separation spring 54 supports the armature 53 at a position axially away from the electromagnet 52 by its biasing force. As a result, the armature 53 becomes rotatable relative to the electromagnet 52, and the retainer 25, which is prevented from rotating by the armature 41 via the intermediate plate 43, also becomes rotatable. When the electromagnet 52 is energized, the electromagnet 52 becomes excited to generate a magnetic circuit passing through the field core 57 and the armature 53, and attracts the armature 53 in the axial direction to the field core 57 against the biasing force of the separation spring 54. . At this time, the armature 53 compresses the separation spring 54 in the axial direction and is pressed against the end surface of the field core 57, so that the armature 53, the intermediate plate 43, and the retainer 25 become unrotatable.

Note that it is also possible to change the separation spring to another non-annular spring such as a compression coil spring, and to distribute the spring at a plurality of locations in the circumferential direction.

When the brake unit 7 is in a non-excited state in which the electromagnet 52 of the electromagnetic brake 27 is not energized, the inner ring 20 is in an idling state in which the inner ring 20 can freely rotate in either forward or reverse rotational directions relative to the outer ring 21. That is, the armature 53 is in a state separated from the electromagnet 52 by the separation spring 54, and the retainer 25 cannot be braked. At this time, even if the inner ring 20 rotates in the forward or reverse direction, the retainer 25 is rotated by the centering spring 26, which rotates together with the inner ring 20, and is held at the released position by the elastic restoring force of the centering spring 26. , the engager 24 held by the retainer 25 does not engage with the cam surface 22 on the outer periphery of the inner ring 20 and the cylindrical surface 23 on the inner periphery of the outer ring 21, and the inner ring 20 and the motor shaft 16 freely rotate in both forward and reverse directions. Is possible.

On the other hand, when the electromagnet 52 of the electromagnetic brake 27 is energized to be in an energized state, it becomes a locked state in which rotation of the inner ring 20 relative to the outer ring 21 can be prevented in either the forward or reverse direction. That is, when the electromagnet 52 is switched to the excited state, the armature 53 is attracted to the electromagnet 52 against the separation spring 54, and is pressed against the end surface of the field core 57, resulting in a frictional contact state. At this time, when the inner ring 20 rotates in either the forward or reverse direction, the rotational force of the shaft 4 is transmitted to the retainer 25 from the centering spring 26, which rotates together with the inner ring 20. However, since the braking force due to the frictional contact between the armature 53, which is prevented from rotating by the retainer 25 via the intermediate plate 43, and the field core 57 of the electromagnet 52 belonging to the stationary system acts on the retainer 25, the retainer The inner ring 20 rotates relative to the inner ring 25. As a result, the retainer 25, which moves in the circumferential direction relative to the inner ring 20, presses one of the pair of extensions 39 of the centering spring 26 in the circumferential direction on the inner surface of the retainer groove 42, causing it to elastically bend. It moves in the circumferential direction against the centering spring 26 from the release position toward the engagement position. When this circumferential movement reaches a predetermined angular amount, the retainer 25 reaches the engagement position, and the engager 24 held by the retainer 25 engages the cam surface 22 on the outer circumference of the inner ring 20 and the cylindrical surface on the inner circumference of the outer ring 21. 23, rotation of the inner ring 20 is prevented, and rotation of the motor shaft 16 connected to the inner ring 20 is also prevented.

That is, the brake unit 7 has an engaged state in which rotational torque can be transmitted from the shaft 4 to the brake case 28 (a state in which rotation of the shaft 4 is prevented), and a disengaged state in which the transmission of the rotational torque is blocked. The state (the state in which the shaft 4 is rotatable) can be switched by controlling the energization of the electromagnet 52.

The control unit 8 shown in FIG. 1 controls the reaction motor 6, the brake unit 7, and the steering motor 12. An external sensor 61, a steering sensor 5, and a steering sensor 13 are electrically connected to the input side of the control unit 8. The external sensor 61 is a vehicle speed sensor or the like that detects the traveling speed of the vehicle. A reaction motor 6, a brake unit 7, and a steering actuator 2 are electrically connected to the output side of the control section 8.

The control unit 8 operates the steering motor 12 according to the amount of operation of the steering wheel 1 detected by the steering sensor 5 and the vehicle running condition (vehicle speed, etc.) detected by the external sensor 61, Control is performed to change the direction of the steered wheels 3. Further, at this time, the control unit 8 controls the reaction force motor 6 to operate so as to generate a steering reaction force of a magnitude corresponding to the operation amount of the steering wheel 1 and the running condition of the vehicle.

Further, the control unit 8 determines whether the orientation of the steered wheels 3 has reached the stroke end based on the position of the steered shaft 10 detected by the steered sensor 13. Here, when it is determined that the direction of the steered wheel 3 has not reached the stroke end, the electromagnet 52 of the brake unit 7 is de-energized to bring the electromagnetic brake 27 into a non-excited state, and the brake unit 7 is activated as described above. Keep it idle. On the other hand, when it is determined that the direction of the steered wheels 3 has reached the stroke end, the electromagnet 52 is energized to turn the electromagnetic brake 27 into an excited state and keep the brake unit 7 in the aforementioned locked state.

This steering device has the above-mentioned configuration, and when the electromagnetic brake 27 of the brake unit 7 is de-energized and the retainer 25 is put in a non-braking state, it is stopped by the shaft 4 so as to rotate together with the shaft 4. Since the centering spring 26 transmits the rotational force of the shaft 4 to the retainer 25 and holds the retainer 25 in the released position relative to the shaft 4, the engager 24 does not engage with the shaft 4 and the inner periphery of the outer ring 21. , rotation of the steering wheel 1 is allowed. On the other hand, when the electromagnetic brake 27 is energized and the retainer 25 is placed in a braking state, even if the steering wheel 1 is rotated, the retainer 25 to which the rotational force of the shaft 4 is transmitted from the centering spring 26 is moved to the electromagnetic brake 27. Since the shaft 4 rotates relative to the retainer 25, and the retainer 25, which moves in the circumferential direction with respect to the shaft 4, reaches the engagement position against the centering spring 26, the engager 24 engages with the inner periphery of the shaft 4 and the outer ring 21, and further rotation of the shaft 4 is reliably prevented. Then, when the electromagnetic brake 27 is switched from the energized state to the non-excited state, the retainer 25 is returned to the release position by the elastic restoring force of the centering spring 26.

Therefore, in this steering device, when the orientation of the steered wheels 3 has not reached the stroke end, the electromagnetic brake 27 is de-energized and the steering operation is possible (steering free state), and the orientation of the steered wheels 3 is at the stroke end. When the electromagnetic brake 27 is switched from a non-excited state to an energized state, the steering wheel 1 is prevented from rotating beyond the circumferential movement amount between the released position and the engaged position of the retainer 25. The steering is locked, and the driver can reliably sense the situation through the steering wheel 1.

Moreover, since two power supply systems are provided to supply electricity to the electromagnet 52 of the electromagnetic brake 27, and the brake unit 7 is provided with electrical redundancy, while electricity is supplied to the electromagnet 52 from the first power supply system, Even if an electrical failure occurs (when the electromagnetic brake 27 is in the excited state), the steering disabled state (steering locked state) can be maintained.

Here, since the number of turns of the two wires 73a and 73b forming the solenoid coil 58 of the electromagnet 52 is the same, the electromagnet 52 can ensure the same attraction force before and after the occurrence of an electrical failure. , no change occurs in the function of the brake unit 7.

Note that in order to reduce the size of the electromagnet 52, the number of turns of the wire 73b connected to the second power supply system may be smaller than the number of turns of the wire 73a connected to the first power supply system. In that case, the number of turns of each wire 73a, 73b may be set to a specification that allows the electromagnet 52 to secure the minimum required attraction force after an electrical failure occurs.

Further, although the number of power supply systems that supply electricity to the electromagnet 52 is two in the embodiment, it may be three or more.

Although the above-mentioned embodiment describes a steering device using a rotation transmission device in a brake unit, the rotation transmission device of the present invention can of course be incorporated into a mechanical device other than a steering device, and electrical failure does not occur. Even if the electromagnet is energized, it is possible to maintain the function of switching between transmission and cutoff of rotational torque from the input side member to the output side member by controlling the energization of the electromagnet.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of this invention is indicated by the claims rather than the above description, and it is intended that all changes within the meaning and range equivalent to the claims are included.

1 Steering wheel 2 Steering actuator 3 Steering wheel (steering section)
4 axis (input side member)
5 Steering sensor 6 Reaction motor 7 Brake unit (rotation transmission device)
8 Control part 16 Motor shaft 20 Inner ring 21 Outer ring 24 Engagement element 25 Retainer 26 Centering spring 27 Electromagnetic brake 28 Brake case (output side member, stationary member)
52 Electromagnet 53 Armature 54 Separation spring 57 Field core 58 Solenoid coils 71a, 71b Power lines 73a, 73b Wire

Claims (5)

It has an input-side member and an output-side member that are rotationally driven, and includes an engaged state in which rotational torque can be transmitted from the input-side member to the output-side member, and an engagement state in which transmission of the rotational torque is interrupted. In a rotation transmission device that switches between a released state and a released state by controlling energization to an electromagnet,
A plurality of power supply systems are provided for supplying current to the electromagnet, and a first power supply system among them is used during normal times, and an electrical loss occurs in the first power supply system while supplying power to the electromagnet from the first power supply system. A rotation transmission device characterized in that, when a failure occurs, the electromagnet is energized from another power supply system. The electromagnet includes an annular field core and a solenoid coil wound around the field core,
The rotation transmission device according to claim 1, wherein a plurality of wires forming the solenoid coil and connected to each of the power supply systems are wound simultaneously. The rotation transmission device according to claim 2, wherein the number of turns of the plurality of wires is the same. The rotation transmission device according to claim 2, wherein the number of turns of the wire connected to a power supply system other than the first power supply system is smaller than the number of turns of the wire connected to the first power supply system. steering wheel and
a steering sensor that detects the amount of operation of the steering wheel;
a steering actuator that changes the direction of a steering section according to the amount of operation of the steering wheel detected by the steering sensor;
A steer-by-wire steering device comprising: a shaft connected to the steering wheel so as to rotate together with the steering wheel;
The rotation transmission device according to any one of claims 1 to 4 includes the shaft as the input side member, and a stationary member that is stationary with respect to the input side member as the output side member,
When the direction of the steering section has not reached its movement limit, the engagement between the shaft and the stationary member is disengaged by stopping power supply to the electromagnet from the first power supply system or another power supply system. the shaft and the steering wheel are rotatable;
When the direction of the steering section reaches its movement limit, the shaft and the stationary member are brought into engagement by energizing the electromagnet, making the shaft and the steering wheel unrotatable. Steer-by-wire steering system.

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