JP2005354828A - Dc motor with brush - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a DC motor fitted with a brush which can vary the rotating torque of a rotor even if there is no current-variable motor driving circuit. <P>SOLUTION: This DC motor 50 with a bush can change the relative position between a field 54 and brushes 55 and 56, by a brush holding housing 53 rotating to a field retaining housing 52. Then, when the brush retaining housing 53 is arranged in a neutral position, winding magnetic flux B2 and field magnetic flux B1 become parallel, so the field 62 is not subjected to the electromagnetic force by the field magnetic flux B1, and rotor rotating torque is not generated. Moreover, when the brush holding housing 53 gets out of the neutral position, the winding magnetic flux B2 and the field magnetic flux B1 are crossed, so the winding 62 is not subjected to the electromagnetic force by the field magnetic flux B1, and rotor rotating torque is generated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a brushed DC motor, and more particularly to a brushed DC motor for turning a steering wheel of an automobile.

In general, a DC motor with a brush includes a field and a brush on a stator, and a rotor including a winding composed of a plurality of coils and a commutator to which end portions of the coils are connected. Then, when the brush contacts a part of the commutator, one of the plurality of coils is excited, and the rotor rotation torque is obtained by the electromagnetic force that the excited coil receives from the field magnetic flux. Further, in order to efficiently obtain the rotor rotational torque, the brush and the commutator are in contact with each other so that the magnetic flux by the coil and the field magnetic flux by the field are orthogonal to each other (see Non-Patent Documents 1 to 3).
Daiki Ebihara “Motor Technology Practical Handbook” published by Nikkan Kogyo Shimbun, published on March 23, 2001, p. 33 The Institute of Electrical Engineers of Japan, “Electrical Equipment Engineering I (Revised Edition)”, Ohm Co., Ltd., published on 8th November 1994, p. 9-10 Yoichi Hori, Tatsuo Teratani, Ryozo Masaki, “Automotive Motor Technology”, published by Nikkan Kogyo Shimbun, June 30, 2003, p. 33-35

  By the way, automobile parts, tools, home appliances, and the like are often used by changing the output torque (rotor torque) of the motor in accordance with a mechanical operation of a predetermined part. However, the conventional brushed DC motor described above requires a current variable motor drive circuit that changes the drive current that flows to the motor in accordance with the operation of a predetermined part.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a brushed DC motor capable of changing the rotor rotational torque without a current variable motor driving circuit.

  In order to achieve the above object, a brushed DC motor according to the first aspect of the present invention has a brush with which a brush provided in a stator and a commutator provided in a rotor are brought into sliding contact with each other to energize windings of the rotor. In a DC motor, a stator is configured such that a brush holding housing that holds a brush is rotatably connected to a field holding housing that holds a field. A neutral position where the brush and commutator contact is included so that a parallel winding flux is generated by the excitation of the winding, and when the brush holding housing deviates from the neutral position, the winding flux crossing the field flux is It is characterized in that the brush and the commutator are in contact with each other as generated by the excitation of the winding.

  The invention of claim 2 is characterized in that, in the brushed DC motor according to claim 1, the winding is composed of a plurality of coils, and the winding magnetic flux is a combination of the magnetic fluxes of the plurality of coils. .

  The invention according to claim 3 is characterized in that in the DC motor with brush according to claim 1 or 2, urging means for urging the brush holding housing toward the neutral position is provided.

  According to a fourth aspect of the present invention, in the brushed DC motor according to any one of the first to third aspects, a winding magnetic flux perpendicular to the field magnetic flux is generated by exciting the winding in the rotatable range of the brush holding housing. It is characterized in that the magnetic flux orthogonal position where the brush and the commutator are in contact with each other is included.

  According to a fifth aspect of the present invention, in the brushed DC motor according to the fourth aspect, there is provided a stopper that abuts when the brush holding housing is shifted from the neutral position to one side and the other side and reaches the magnetic flux orthogonal position. It has features.

  The invention of claim 6 is characterized in that, in the DC motor with brush according to any one of claims 1 to 5, a housing locking means for locking the brush holding housing at a position shifted from the neutral position is provided. Have.

  According to a seventh aspect of the present invention, in the DC motor with brush according to the sixth aspect, the housing lock means is characterized in that the brush holding housing is held at a position perpendicular to the magnetic flux.

  A brushed DC motor according to an eighth aspect of the invention is a brushed DC motor for turning a steered wheel provided in a vehicle, wherein a brush provided in a stator and a commutator provided in a rotor are brought into sliding contact with each other. In the brushed DC motor for energizing the windings of the rotor, the stator is formed by rotatably connecting the brush holding housing holding the brush to the field holding housing holding the field, and the brush holding housing. Is provided with a handle connecting portion to which a handle provided in the vehicle is connected via a relay member, and a winding magnetic flux parallel to the field magnetic flux is generated by excitation of the winding in a rotatable range of the brush holding housing. A neutral position where the brush and commutator contact as included is included, and when the brush holding housing deviates from the neutral position, the winding flux crossing the field flux is Having characterized in that the brush and the commutator are in contact so as to be generated by magnetic.

[Inventions of Claims 1 and 2]
In the DC motor with brush according to claim 1, the relative position between the field magnet and the brush is changed by rotating the brush holding housing with respect to the field holding housing, and the angle formed by the field flux and the winding flux is also Be changed. When the brush holding housing is disposed at the neutral position, the winding magnetic flux and the field magnetic flux are parallel to each other. Therefore, the winding does not receive electromagnetic force due to the field magnetic flux, and no rotor rotational torque is generated. When the brush holding housing deviates from the neutral position, the winding magnetic flux and the field magnetic flux intersect each other, so that the winding receives an electromagnetic force due to the field magnetic flux and generates rotor rotational torque. As described above, in the brushed DC motor of the present invention, the rotor rotational torque changes according to the mechanical rotational position of the brush holding housing. That is, according to the brushed DC motor of the present invention, the rotor rotational torque can be changed without a motor drive circuit with variable current. The winding magnetic flux may be a combination of magnetic fluxes of a plurality of coils constituting the winding (invention of claim 2).

[Invention of claim 3]
According to the DC motor with brush of the third aspect, unless the external torque is applied to the brush holding housing, the brush holding housing is held at the neutral position by the urging means, and the rotor can be stopped.
If the urging means is made of an elastic member, and the elastic force (the urging force) increases as the brush holding housing moves away from the neutral position, the urging means is in accordance with the magnitude of the external torque applied to the brush holding housing. Thus, the rotor rotational torque can be changed.

[Invention of claim 4]
In the DC motor with a brush according to the fourth aspect, by setting the brush holding housing at the magnetic flux orthogonal position, the winding magnetic flux and the field magnetic flux are orthogonal to each other, and the rotor rotational torque can be maximized.

[Invention of claim 5]
In the DC motor with brush according to the fifth aspect, when the brush holding housing is rotated from the neutral position to the one side or the other side to the limit, the brush holding housing abuts against the stopper and can be positioned at the magnetic flux orthogonal position.

[Inventions of Claims 6 and 7]
In the DC motor with brush according to the sixth aspect, the brush holding housing can be locked at a position shifted from the neutral position and used as a normal DC motor with brush. Here, if the brush holding housing is locked at the position perpendicular to the magnetic flux as in the configuration of the seventh aspect, the rotor rotational torque can be held at the maximum.

[Invention of Claim 8]
In the DC motor with brush according to the eighth aspect, the brush holding housing is rotated in conjunction with the turning operation of the handle, and the steering wheel can be steered by the DC motor with brush.

[First Embodiment]
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, the brushed DC motor 50 of the present embodiment includes a pair of brushes 55 and 56 in a stator 51. As shown in FIG. 4A, both brushes 55 and 56 are aligned with each other and face each other, with one brush 55 connected to the positive electrode of the DC power source and the other brush 56 connected to the negative electrode. ing. Further, as shown in FIG. 4B, the field magnet 54 provided in the stator 51 is formed by, for example, arranging a pair of permanent magnets 73 and 74 so that the field flux B1 is one permanent magnet. 73 toward the other permanent magnet 74.

  The rotor 60 is provided with a commutator 63 (so-called commutator) corresponding to the brushes 55 and 56. As shown in FIG. 4A, for example, four arc-shaped segments 71 are laid on the peripheral surface of the commutator 63. Further, the winding 62 provided on the rotor 60 is constituted by, for example, two coils 70 and 70. These coils 70 are arranged such that their winding axes are orthogonal to each other, as conceptually shown in FIG. Further, both terminals of one coil 70 are connected to a pair of segments 71 and 71 arranged opposite to each other, and both terminals of the other coil 70 are connected to the remaining pair of segments 71 and 71 opposed to each other. Has been. Then, depending on the rotational position of the rotor 60, the brushes 55 and 56 selectively come into contact with a pair of opposed segments 71 and 71 among the four segments 71, thereby exciting one of the coils 70. The winding magnetic flux B2 is generated by the winding 62.

  As shown in FIG. 1, the stator housing 51 </ b> H includes a field holding housing 52 that holds a field 54 (permanent magnets 73 and 74) and a brush holding housing 53 that holds brushes 55 and 56. The brush holding housing 53 is rotatably connected to the field holding housing 52 via a bearing 51B.

  The rotatable range of the brush holding housing 53 is restricted within a range of 180 degrees by a stopper 68 provided on the fixed wall 65 and a protrusion 69 provided on the brush holding housing 53. The fixed wall 65 is adjacent to the side of the brush holding housing 53, and is fixed or integrally formed with the field holding housing 52, for example. The fixed wall 65 is provided with a lock device 66 (corresponding to “housing lock means” according to the present invention) for holding the brush holding housing 53 in a non-rotatable manner. The locking device 66 has a structure in which the locking pin 67 is directly moved by solenoid driving, and the locking pin 67 is inserted into a locking hole 59 formed in the brush holding housing 53 to lock the brush holding housing 53.

  Further, as shown in FIG. 1, a neutral point return spring 58 (corresponding to “biasing means” of the present invention) is provided between the brush holding housing 53 and the fixed wall 65. The neutral point return spring 58 is formed by spirally winding a leaf spring material, and the end of the spiral on the center side is fixed near the center of the brush holding housing 53, while the outer end of the spiral is a fixed wall. It is fixed to 65. The neutral point return spring 58 urges the brush holding housing 53 to a midpoint within a rotatable range.

  An external force applying shaft 57 projects from the center of the outer surface of the brush holding housing 53. Then, the external force applying shaft 57 receives external torque, and the brush holding housing 53 rotates.

  Both ends in the range in which the brush holding housing 53 can rotate correspond to the “magnetic flux orthogonal position” according to the present invention, and the midpoint in the rotatable range corresponds to the “neutral position” in the present invention. The brush holding housing 53 is locked at one magnetic flux orthogonal position by the lock device 66.

  When the brush holding housing 53 is locked at the magnetic flux orthogonal position, as shown in the conceptual diagram of FIG. 2, the brushes 55, 56 are connected to the segments 71, 71 connected to the coil 70 having the winding axis orthogonal to the field magnetic flux B1. Touch. As a result, an exciting current in a predetermined direction flows through the coil 70, and a winding magnetic flux B2 orthogonal to the field magnetic flux B1 is generated. Then, the winding 62 receives the electromagnetic force generated by the field magnetic flux B1, and the rotor rotational torque is generated. In FIG. 2, the energized coil 70 and the segment 71 are shown in gray.

  4A and 4B show a cross-sectional view of the brushed DC motor 50 viewed from the same axial direction in a state where the brush holding housing 53 is locked at a position perpendicular to the magnetic flux. Has been. FIG. 4B shows only one excited coil 70. Here, when the rotor 60 is rotated in the counterclockwise direction by the rotor rotational torque from the state shown in FIG. 4B, the winding magnetic flux B2 is also counterclockwise from the state in which the winding magnetic flux B2 is orthogonal to the field magnetic flux B1. Rotate to. When the rotor 60 rotates about 90 degrees in mechanical angle, the segments 71 and 71 with which the brushes 55 and 56 come into contact are switched, and the other coil 70 is excited this time. At this time, the winding magnetic flux B2 generated by the other excited coil 70 is deviated by about 90 degrees from the field magnetic flux B1, and the direction of the winding magnetic flux B2 moves to the side perpendicular to the field magnetic flux B1 as the rotor 60 rotates. I will do it. That is, the winding magnetic flux B2 always changes within a range of about 90 degrees centering on a position orthogonal to the field magnetic flux B1, and the field magnetic flux B1 and the winding magnetic flux B2 are always kept in a state of crossing the rotor. 60 continues to rotate. That is, in a state where the brush holding housing 53 is locked at the magnetic flux orthogonal position, the brushed DC motor 50 functions as a normal brushed DC motor.

  When the lock of the lock device 66 is released, the brush holding housing 53 is held at the neutral position by the elastic force of the neutral point return spring 58. Then, as shown in the conceptual diagram of FIG. 3, the brushes 55 and 56 come into contact with the segments 71 and 71 to which the coil 70 having a winding axis parallel to the field magnetic flux B1 is connected. Then, when an exciting current in a predetermined direction flows through the coil 70, a winding magnetic flux B2 substantially parallel to the field magnetic flux B1 is generated, the winding 62 does not receive electromagnetic force due to the field magnetic flux B1, and the rotor 60 is in the stator 51. Against the rotation. In FIG. 3, the energized coil 70 and the segment 71 are shown in gray. 5A and 5B show cross-sectional views of the brushed DC motor 50 viewed from the same axial direction in a state where the brush holding housing 53 is held at the neutral position. Has been.

  When the brush holding housing 53 in the state shown in FIG. 5 (A) receives external torque on the external force applying shaft 57, for example, as shown in FIG. 6 (A), the brush holding housing 53 moves away from the neutral position. A clockwise shift of θ degrees, for example, the brush holding housing 53 is arranged between the neutral position and the magnetic flux orthogonal position. Then, as shown in FIG. 6 (B), a winding magnetic flux B2 is generated that faces in a direction intersecting with the field magnetic flux B1 at θ degrees. As a result, the winding 62 receives the electromagnetic force generated by the field magnetic flux B1, and generates a rotor rotational torque that rotates the rotor 60 in the clockwise direction in FIG. 6B.

  Here, the scalar value of the field flux B1 is ΦM, the scalar value of the winding flux B2 is ΦI, the crossing angle between the field flux B1 and the winding flux B2 is θ (see FIG. 6B), and the constant is K. The rotor rotational torque T can be obtained by the following equation (1).

    T = K ・ ΦM ・ ΦI ・ SINθ ・ ・ ・ ・ (1)

  Accordingly, the rotor rotational torque T increases as the angle θ at which the brush holding housing 53 deviates from the midpoint position approaches 90 degrees, and when the brush holding housing 53 comes into contact with the stopper 68 and reaches the magnetic flux orthogonal position (see FIG. 7). The rotor rotational torque T is maximized.

  When the brush holding housing 53 receives external torque and rotates in the opposite direction to the above-described case shown in FIGS. 6A and 7A, the above case does not indicate the rotor rotational torque. The direction is reversed.

  As described above, according to the brushed DC motor 50 of the present embodiment, the rotor rotational torque can be changed according to the mechanical operation of the external force applying shaft 57 without a current variable motor drive circuit. In addition, since the neutral point return spring 58 that urges the brush holding housing 53 toward the neutral position is provided, the rotor rotational torque of the brushed DC motor 50 is adjusted according to the magnitude of the external torque applied to the external force applying shaft 57. Can be changed. In addition, the brush holding housing 53 can be used as an ordinary brushed DC motor 50 by locking the brush holding housing 53 to a position shifted from the neutral position (specifically, “magnetic flux orthogonal position”) by the lock device 66.

  In the present embodiment, the winding 62 is constituted by the two coils 70, but the number of coils constituting the winding may be three or more. In the above embodiment, since the winding 62 is constituted by the two coils 70, the winding magnetic flux B2 varies in the range of 45 degrees with respect to the field magnetic flux B1 with the brush holding housing 53 fixed. By increasing the number of coils to be configured, the variation range of the winding magnetic flux with respect to the field magnetic flux can be narrowed. Further, as described in the second embodiment below, the winding magnetic flux of the winding may be a combination of magnetic fluxes of a plurality of coils constituting the winding.

[Second Embodiment]
This embodiment is shown in FIGS. 8 and 9, and the structure of the rotor 60 ′ is mainly different from the rotor 60 of the first embodiment. Hereinafter, only the configuration different from that of the first embodiment will be described, and the same portions as those of the first embodiment are denoted by the same reference numerals, and redundant description will be omitted.

  As shown in FIG. 8, the rotor 60 ′ in the brushed DC motor of this embodiment includes a rotor core 72 having three teeth 72 </ b> T. The teeth 72T are arranged with an interval of 120 degrees, and coils 70U, 70V, and 70W are wound around the three teeth 72T. As shown in FIG. 9, the coils 70U, 70V, and 70W are star-connected to form a winding 62.

  Further, for example, as shown in FIG. 9, the commutator 63 provided in the rotor 60 ′ is provided with six segments 71, and the opposed segments 71 are electrically connected. And the terminal of each coil 70U, 70V, 70W is connected to these three pairs of segments.

  FIG. 9 shows a state in which the brush holding housing 53 described in the first embodiment is disposed at a position perpendicular to the magnetic flux. In this state, the three coils 70U, 70V, and 70W are all excited, the magnetic flux B10 generated by the coil 70U is directed perpendicular to the field magnetic flux B1 and away from the center of the rotor 60 (see FIG. 8), and the magnetic flux B11 generated by the coil 70V. Crosses the field magnetic flux B1 at an angle of 30 degrees toward the center of the rotor 60, and the magnetic flux B12 generated by the coil 70W intersects the field magnetic flux B1 at an angle of 120 degrees toward the center of the rotor 60. The winding magnetic flux B2 of the entire winding 62 is composed of magnetic fluxes B10, B11, and B12 generated by the coils 70U, 70V, and 70W, and is in a state orthogonal to the field magnetic flux B1. Thereby, a rotor rotational torque is generated and the rotor 60 rotates.

  Also in this embodiment, by rotating the brush holding housing 53 as in the first embodiment, the direction of the winding magnetic flux B2 of the entire winding 62 is changed, and the brush holding housing 53 is disposed at the neutral position. When this is done, the winding magnetic flux B2 becomes parallel to the field magnetic flux B1, and the rotor rotational torque becomes zero.

[Third Embodiment]
Hereinafter, an embodiment of the present invention will be described with reference to FIGS.
FIG. 10 shows the overall configuration of the steer-by-wire system 10 including the brushed DC motor 50 according to the present invention. In the figure, reference numeral 11 denotes a handle, which is fixed to one end of the steering shaft 12. The steering shaft 12 is rotatably supported on the vehicle body, and a reaction force generator 13 is connected to the other end of the steering shaft 12.

  For example, as shown in FIG. 11, the reaction force generator 13 has a configuration in which a worm gear 19 fixed to the output rotation shaft of the reaction force motor 14 is engaged with a worm wheel 20 fixed to one end of the steering shaft 12. . Then, the output torque of the reaction force motor 14 is applied to the steering shaft 12 as a reaction force to the steering wheel operation.

  Further, the reaction force generator 13 is provided with a mechanical reaction force generation spring 21 in case the reaction force motor 14 fails. Specifically, the reaction force generation spring 21 has a spiral structure, one end of which is fixed to the front end of the steering shaft 12 and the other end is fixed to one end of the clutch 22. The other end of the clutch 22 is fixed to the body of the vehicle. When the reaction force motor 14 fails, the clutch 22 is connected, and the steering shaft 12 is fixed to the body via the reaction force generating spring 21. Is done.

  A torsion bar 16 is provided in the middle of the steering shaft 12, and rotational position sensors 17, 17 are provided at both ends of the torsion bar 16. The steering angle of the handle 11 is detected by one rotational position sensor 17, and the handle is determined from the torsion angle of the torsion bar 16 and the spring rigidity of the torsion bar 16 based on the difference between the detection results of the rotational position sensors 17 and 17. 11 actually detects the load torque.

  An interlocking shaft 27 is connected to the steering shaft 12 via bevel gears 23 and 24 and spur gears 25 and 26. The interlocking shaft 27 is connected to one end of the steering force transmission clutch 28, and the flexible cable 29 is connected to the other end of the steering force transmission clutch 28. The steering force transmission clutch 28 is in a disconnected state.

  As shown in FIG. 10, a steering rack 31 is passed between a pair of steering wheels 30, 30 provided in the vehicle, and tie rods 32, 32 connected to both ends of the steering rack 31 are respectively steered. It is connected to the wheels 30, 30. The steerable rack 31 is inserted into the cylindrical housing 80, and the cylindrical housing 80 is fixed to the main body of the vehicle. The handle 11 is mechanically separated from the portions connected to the steering wheels 30, 30, and in order to steer the steering wheel 30 according to the handle 11, the axial direction of the cylindrical housing 80 is determined. The brushed DC motor 50 described in the first embodiment is assembled in the intermediate portion. Specifically, as shown in FIG. 11, the pinion 33 provided on the rotating shaft of the brushed DC motor 50 meshes with the steered rack 31, and when the pinion 33 rotates, the steered rack 31 moves directly, As a result, the steered wheels 30, 30 are steered. One end of the flexible cable 29 is connected to the external force applying shaft 57 of the brushed DC motor 50.

  A linear motion position sensor 37 (see FIG. 10) is attached to a portion of the cylindrical housing 80 away from the brushed DC motor 50. The linear motion position sensor 37 is formed, for example, by connecting a detection shaft that meshes with the steerable rack 31 and rotates in conjunction with an absolute encoder, for example. Thereby, the actual linear motion position of the steerable rack 31 can be detected.

  The entire steer-by-wire system 10 is controlled by an ECU 35 (ECU is an abbreviation for “Electric Control Unit”). Normally, the locking device 66 is locked by the ECU 35, thereby locking the brush holding housing 53 of the DC motor 50 with brush. The clutch 22 and the steering force transmission clutch 28 are disconnected by the ECU 35. Then, the reaction program motor 14, the steering force transmission clutch 28, the brushed DC motor 50, and the lock device 66 are driven and controlled by executing the control program PG 1 shown in FIG. 12 at a predetermined cycle. Specifically, when the control program PG1 is executed, the ECU 35 takes in the detection results of each sensor such as the rotational position sensor 17, the vehicle speed sensor 36, the linear motion position sensor 37 (see FIG. 10) (S1).

  Next, it is checked whether or not the value of any one of the sensors is an abnormal value (that is, any sensor has failed) (S2). If the values of any of the sensors are normal values (S2: NO), the transmission ratio R between the steering wheel 11 and the steered wheels 30 is determined according to the vehicle speed (S3). Here, when the steering angle of the steering wheel 11 is θ1 and the turning angle of the steered wheels 30 is θ2, the transmission ratio R described above can be obtained from the following equation (2).

    R = θ2 / θ1 (2)

  Then, the ECU 35 acquires a predetermined transmission ratio R from the map 42 shown in FIG. 13 according to the vehicle speed. The map 42 is set so that the transmission ratio R decreases as the vehicle speed increases. That is, when the vehicle speed is relatively low (during low speed traveling), a relatively large transmission ratio R is employed. As a result, the vehicle can be turned by a slight operation of the handle 11, and garage entry or the like is facilitated. On the other hand, when the vehicle speed is relatively high (during high-speed traveling), a relatively small transmission ratio R is adopted, which prevents sudden steering (rapid turning) and enables stable traveling.

  The ECU 35 obtains the target turning angle of the steered wheels 30 from the determined transmission ratio R and the steering angle θ1 of the handle 11, and the brushed DC motor 50 for making the steered angle of the steered wheels 30 coincide with the target turning angle. The target rotation position is determined (S4). Then, a drive current corresponding to the deviation between the actual rotational position of the brushed DC motor 50 calculated from the detection result of the linear motion position sensor 37 and the target rotational position is supplied to the brushed DC motor 50 (S5). At this time, since the brush holding housing 53 is locked by the locking device 66, the brushed DC motor 50 operates as a normal brushed DC motor.

  Next, the ECU 35 estimates the steering resistance of the steered wheels 30 due to the friction between the steered wheels 30 and the road surface based on the drive current necessary to steer the brushed DC motor 50 (S6). Then, the target steering reaction force of the handle 11 is determined with respect to the estimated steering resistance (S7). At this time, the target steering reaction force is determined to be a relatively large value during high speed traveling, while the target steering reaction force is determined to be a relatively small value during low speed traveling. Then, the steering reaction force actually applied to the steering wheel 11 is detected by the steering angle / torque sensor 15, and the reaction force motor 14 of the reaction force generator 13 is adjusted so that the actual steering reaction force coincides with the target steering reaction force. A drive current is supplied (S8), and the control program PG1 is exited. Then, the control program PG1 is executed again after a predetermined period.

  When the value of any sensor is an abnormal value (when the sensor has failed) (S2: YES), the lock by the lock device 66 is released (S9), and the clutch 22 and The steering force transmission clutch 28 is brought into a connected state (S10). Specifically, the lock by the locking device 66 is released, and the brush holding housing 53 of the brushed DC motor 50 is moved to the neutral position by the resilient force of the neutral point return spring 58, and then the steering force transmission clutch 28 is connected. To. Then, the control program PG1 is exited and processing is performed so that the control program PG1 is not re-executed.

  With the above configuration, when the sensor value becomes abnormal (so-called failure), a steering reaction force can be applied to the handle 11 by the reaction force generation spring 21 instead of the reaction force motor 14. The handle 11 is coupled to the external force applying shaft 57 of the brushed DC motor 50 via the flexible cable 29 or the like. As a result, when the handle 11 is cut to one side, the brush holding housing 53 is rotated to one side from the neutral position, the pinion 33 is rotated to one side together with the rotor 60, the steered wheels 30 are steered, and the handle 11 is turned. When cut to the other side, the brush holding housing 53 is rotated from the neutral position to the other, the pinion 33 is rotated together with the rotor 60, and the steering wheel 30 is steered to the opposite side. At this time, the greater the angle at which the handle 11 is turned, the greater the rotation angle of the brush holding housing 53, and the steered wheels 30 are reliably steered against self-aligning torque.

[Other Embodiments]
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various other than the following are within the scope not departing from the gist. It can be changed and implemented.
(1) The brushed DC motor 50 according to the first embodiment is configured to apply an external torque to the brush holding housing 53. For example, the brush holding housing 53 is configured by applying an external torque to the field holding housing 52. The field holding housing 52 may be relatively rotated.

  (2) In the third embodiment, the brush DC motor 50 applied to the steer-by-wire system 10 is excited. However, the application target of the brush DC motor according to the present invention is not limited to the steer-by-wire system. Absent.

  (3) In the third embodiment, when the sensor has failed, the handle 11 and the brush holding housing 53 of the brushed DC motor 50 are connected. However, the ECU 35 is connected to the brushed DC motor 50. When the control circuit for changing the drive current fails, the handle 11 and the brush holding housing 53 of the brushed DC motor 50 may be connected.

Sectional drawing of the DC motor with a brush which concerns on 1st Embodiment of this invention. Conceptual diagram of the state where the brush holding housing is arranged at the position perpendicular to the magnetic flux Conceptual diagram of the brush holding housing in the neutral position Sectional view of brushed DC motor with brush holding housing arranged at magnetic flux orthogonal position Sectional view of brushed DC motor with brush holding housing in neutral position Sectional view of brushed DC motor with brush holding housing displaced from neutral position Sectional view of brushed DC motor with brush holding housing rotated to position perpendicular to magnetic flux Sectional drawing of DC motor with brush of 2nd Embodiment Conceptual diagram of DC motor with brush The block diagram of the steer-by-wire system of 3rd Embodiment Conceptual diagram of steer-by-wire system Flow chart of control program Data map for testing transmission ratio

Explanation of symbols

10 Steer-by-wire system 11 Handle 29 Flexible cable (relay member)
30 Steering wheel 50 DC motor with brush 52 Field holding housing 53 Brush holding housing 57 External force applying shaft (handle connecting portion)
58 Neutral point return spring 60, 60 'Rotor 62 Winding 63 Commutator 66 Locking device 70, 70U, 70V, 70W Coil B1 Field flux B2 Winding flux

Claims (8)

In a brushed DC motor that energizes the windings of the rotor by bringing the brush provided on the stator into sliding contact with the commutator provided on the rotor,
The stator is formed by rotatably connecting a brush holding housing holding the brush to a field holding housing holding a field,
The rotatable range of the brush holding housing includes a neutral position where the brush and the commutator are in contact with each other so that a winding magnetic flux parallel to a field magnetic flux is generated by excitation of the winding.
The brush and the commutator are in contact with each other so that a winding magnetic flux intersecting a field magnetic flux is generated by excitation of the winding when the brush holding housing is displaced from the neutral position. DC motor.   2. The brushed DC motor according to claim 1, wherein the winding includes a plurality of coils, and the winding magnetic flux is a combination of the magnetic fluxes of the plurality of coils.   The brushed DC motor according to claim 1, further comprising a biasing unit that biases the brush holding housing toward the neutral position.   The rotatable range of the brush holding housing includes a magnetic flux orthogonal position where the brush and the commutator contact so that a winding magnetic flux orthogonal to a field magnetic flux is generated by excitation of the winding. The brushed DC motor according to any one of claims 1 to 3.   5. The DC motor with brush according to claim 4, further comprising a stopper that abuts when the brush holding housing is shifted from the neutral position to one side and the other side to reach the magnetic flux orthogonal position. .   6. The brushed DC motor according to claim 1, further comprising housing locking means for locking the brush holding housing at a position shifted from the neutral position.   7. The brushed DC motor according to claim 6, wherein the housing locking means holds the brush holding housing at a position perpendicular to the magnetic flux. A brushed DC motor for turning a steered wheel provided in a vehicle, wherein a brush provided in a stator and a commutator provided in a rotor are brought into sliding contact with each other to energize a winding of the rotor. In the motor
The stator is configured such that a brush holding housing holding the brush is rotatably connected to a field holding housing holding a field, and a handle provided in the vehicle is connected to the brush holding housing. A handle connecting portion connected via
The rotatable range of the brush holding housing includes a neutral position where the brush and the commutator are in contact with each other so that a winding magnetic flux parallel to a field magnetic flux is generated by excitation of the winding.
The brush and the commutator are in contact with each other so that a winding magnetic flux that intersects a field magnetic flux is generated by excitation of the winding when the brush holding housing is displaced from the neutral position. DC motor.