JP4561971B2 - Steer-by-wire system - Google Patents

Description

  The present invention relates to a steer-by-wire system in which a steered wheel and a handle are mechanically separated and the steered wheel is steered by a brushless motor in accordance with the handle operation.

  In general, this type of steer-by-wire system is configured to detect a steering position of a steering wheel with a position sensor and drive a brushless motor with a motor drive control circuit based on the detection result to steer the steered wheels. For this reason, when the motor drive control circuit and the position sensor fail, the steered wheels cannot be steered according to the steering wheel operation. On the other hand, a steer-by-wire system in which the motor drive control circuit and the position sensor have triple redundancy has been conventionally known (see, for example, Patent Document 1).

JP 2003-200840 A (Claim 1, Claim 4, FIG. 1)

  However, in the conventional steer-by-wire system described above, the same configuration is simply provided in triplicate to provide redundancy, and therefore, all the triple configurations may fail due to the same cause. Is low. Further, since the triple redundancy is provided, there arises a problem that the mounting space increases approximately three times.

  The present invention has been made in view of the above circumstances, and even if the motor drive control circuit fails, the steered wheels can be steered according to the steering operation, and the mountability to the vehicle is also excellent. The purpose is to provide a steer-by-wire system.

The steer-by-wire system according to the invention of claim 1 made to achieve the above object mechanically separates a steering wheel and a steered wheel provided in a vehicle and provides a brushless motor as a drive source for steering the steered wheel. In a steer-by-wire system in which a brushless motor is driven by a motor drive control circuit according to a handle operation to steer a steered wheel, a plurality of segments connected to a plurality of phase circuits of the brushless motor, and the plurality of segments A fixed commutator on the outer peripheral surface, a brush holder that rotates relative to the commutator, and fixed to the brush holder and connected to the positive and negative electrodes of the battery. A mechanical rectifier is composed of a pair of brushes in contact with the brush holder or commutator. Either one of, and linked to interlocked rotate the handle, during normal, electrically severed mechanical rectifier from the battery or a brushless motor, when the motor drive control circuit is defective, the battery and brushless mechanical rectifier It is characterized in that motor power supply switching means for electrical connection to the motor is provided.

  According to a second aspect of the present invention, in the steer-by-wire system according to the first aspect, the phase circuit includes three phases of a U phase, a V phase, and a W phase, and the segments are evenly arranged in the circumferential direction of the outer peripheral surface of the commutator. The width of the brush is set to be larger than the interval between adjacent segments and smaller than the width of each segment, and one brush is in contact with two adjacent segments of the U phase, V phase, and W phase. The other brush is characterized in that it is configured to contact the remaining one-phase segment.

  According to a third aspect of the present invention, in the steer-by-wire system according to the second aspect, an odd number of segments is provided for each phase circuit, and a gap between adjacent segments of any one of the U phase, the V phase, and the W phase is provided. On the other hand, it is characterized in that the remaining one-phase segment is arranged at a position opened 180 degrees in the circumferential direction of the commutator.

  According to a fourth aspect of the present invention, in the steer-by-wire system according to the third aspect, a total of nine segments are provided for each of the U phase, the V phase, and the W phase, and the nine segments are arranged around the commutator. It is characterized by being arranged in the order of U phase, V phase, W phase, U phase, V phase, W phase, U phase, V phase, and W phase along the direction.

  According to a fifth aspect of the present invention, in the steer-by-wire system according to any one of the first to fourth aspects, the brush holder has a cylindrical shape surrounding the commutator, and the pair of brushes are formed on the inner peripheral surface of the brush holder. It has a characteristic where it is placed.

  According to a sixth aspect of the present invention, in the steer-by-wire system according to the fifth aspect, the brush holder is coupled so as to rotate in conjunction with the handle, and a pair of slides connected to the brushes are provided on the outer peripheral surface of the brush holder. It is characterized in that a ring is laid and provided with a pair of power supply brushes slidably pressed against each sliding ring and connected to the positive and negative electrodes of the battery.

  According to a seventh aspect of the present invention, in the steer-by-wire system according to any one of the first to sixth aspects, the motor power supply switching means is provided between the mechanical rectifier and the brushless motor, or between the mechanical rectifier and the battery. It is characterized in that it is composed of a B contact provided at any one of them and an A contact provided between the motor drive control circuit and the brushless motor or between the motor drive control circuit and the battery.

  According to the steer-by-wire system of the first aspect, at the normal time, the steered wheels can be steered by driving the brushless motor by the motor drive control circuit in accordance with the handle operation. When the motor drive control circuit fails, a mechanical rectifier is connected between the brushless motor and the battery, and the brush and commutator of the mechanical rectifier rotate relative to the handle operation to rotate the handle. The brushless motor can be driven to follow. That is, the segment in contact with the brush is switched in conjunction with the handle operation, and the positive and negative electrodes of the battery are switched and connected to each phase circuit of the brushless motor. Thereby, the phase current to the phase circuit of the brushless motor is changed, the brushless motor is driven, and the steered wheels can follow the rotation of the steering wheel to be steered.

  Further, in the present invention, in addition to the motor drive control circuit, a mechanical rectifier having a configuration different from that of the motor drive control circuit is provided. Therefore, there is a possibility that both the mechanical rectifier and the motor drive control circuit are lost. Low and reliability is improved. In addition, when driving a brushless motor with a mechanical rectifier, the position sensor detection result is not required, so there is no need to provide the position sensor with redundancy, and the installation space can be reduced (that is, mountability). Also excellent).

  According to the steer-by-wire system of claim 2, when one brush comes into contact with any two adjacent segments, the other brush comes into contact with the remaining one-phase segment. As the brush holder and commutator rotate relative to each other, the combination of the segment and the brush that are in contact with each other is sequentially switched to generate a three-phase alternating current. Thereby, the excitation state of each coil which comprises each phase circuit of a brushless motor changes sequentially, and the rotor of a brushless motor can be rotated.

  Here, in the configuration according to claim 2, if the remaining one-phase segment is arranged at a position opened 180 degrees in the circumferential direction of the commutator with respect to the gap between the adjacent segments of any two phases, it corresponds to this. Thus, the arrangement of the pair of brushes can be arranged symmetrically at a position opened 180 degrees, and the brush holder can have a simple structure as compared with the case where the arrangement is asymmetrical (invention of claim 3).

  Furthermore, as in the configuration of claim 4, a total of nine segments are provided for each of the U phase, the V phase, and the W phase, and the nine segments are arranged in the U phase along the circumferential direction of the commutator. , V-phase, W-phase, U-phase, V-phase, W-phase, U-phase, V-phase, W-phase are arranged in order, so that the phase current can be switched smoothly and the motor smoothly Can be rotated.

  Further, as in the configuration of claim 5, the contact portion between the brush and the segment is protected by surrounding the commutator with the brush holder and arranging a pair of brushes on the inner peripheral surface of the brush holder. Can do.

  Furthermore, according to the structure of Claim 6, it can supply to a mechanical rectifier stably from a battery irrespective of the rotation position of the brush holder which rotates in conjunction with a handle.

  According to the configuration of the seventh aspect, the A contact and the B contact can be operated in a normal state. The mechanical rectifier is disconnected from the battery or the phase circuit by the activated B contact, while the motor drive control circuit is connected to the battery and the phase circuit by the activated A contact. As a result, the brushless motor can be driven by the motor drive control circuit during normal operation. On the other hand, in the event of failure where the A contact and the B contact cannot be operated, the mechanical rectifier is connected to the battery and the phase circuit by the B contact, while the motor drive control circuit is disconnected from the battery or the phase circuit by the A contact. . Thus, when the motor drive control circuit fails, the brushless motor can be driven by the mechanical rectifier.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows an overall configuration of a steer-by-wire system 10 according to the present invention. In this steer-by-wire system 10, the handle 11 and the steered wheels 50, 50 are mechanically separated.

  First, the part mechanically connected to the steered wheel 50 will be described. A rack 16 is passed between the pair of steered wheels 50, 50, and tie rods 17, 17 coupled to both ends of the rack 16 are coupled to the steered wheels 50, 50. The rack 16 is inserted into the cylindrical housing 18, and the cylindrical housing 18 is fixed to the vehicle body. A gear box 18G is attached to the cylindrical housing 18, and a pinion gear 19 protruding from the gear box 18G into the cylindrical housing 18 is engaged with the rack 16. A worm wheel 19W that rotates integrally with the pinion gear 19 is provided inside the gear box 18G. Further, the stator of the brushless motor 20 is fixed to the outer surface of the gear box 18G, and the worm gear 20W fixed to the rotor rotation shaft 26R of the brushless motor 20 meshes with the worm wheel 19W described above inside the gear box 18G. ing. As a result, when the brushless motor 20 is driven, the rack 16 linearly moves in the cylindrical housing 18 and the steered wheels 50 and 50 are steered.

  FIG. 2 shows a cross-sectional view of the brushless motor 20. As shown in the figure, the rotor 26 of the brushless motor 20 has an eight-pole structure in which a plurality of permanent magnets 27 are fixed to the outer peripheral surface, and N and S poles are alternately repeated in the circumferential direction. Yes.

  On the other hand, the stator 21 of the brushless motor 20 is provided with, for example, nine teeth 22, and coils 23U, 23V, 23W,. As shown in FIG. 3, the winding 24 of the brushless motor 20 including these coils 23U, 23V, 23W,... Is a three-phase circuit in which three phase circuits 24U, 24V, 24W are star-connected. Three coils are arranged in series for each phase circuit 24U, 24V, 24W. Specifically, the U-phase circuit 23U includes a pair of positive magnetic coils 23U and 23U and one reverse magnetic coil 23u, and the V-phase circuit 23V includes 1 A pair of positive magnetic pole coils 23V and 23V and one reverse magnetic pole coil 23v are provided. Further, the W-phase circuit 23W includes a pair of positive magnetic pole coils 23W and 23W, 1 And two reverse magnetic pole coils 23w. These coils are arranged in the order of coils 23V, 23v, 23U, 23W, 23w, 23V, 23U, 23u, and 23W in the clockwise direction in FIG.

  The positive magnetic pole coils 23U, 23V, and 23W and the reverse magnetic pole coils 23u, 23v, and 23w have opposite winding directions with respect to the teeth 22, and have opposite polarities. Yes. Further, the brushless motor 20 is provided with a position sensor 29 (see FIG. 1) for detecting the rotational position of the rotor 26.

  Next, the part mechanically connected to the handle 11 will be described. As shown in FIG. 4, the distal end portion of the steering shaft 12 extending from the center of the handle 11 protrudes into the gear box 30, and the worm wheel 12 </ b> W is fixed to the distal end of the steering shaft 12 in the gear box 30. ing. Further, a reaction force motor 31 is fixed to the gear box 30, and a worm gear 31 </ b> W is attached to one end of a rotor rotation shaft 31 </ b> R of the reaction force motor 31. The worm gear 31W and the worm wheel 12W are engaged with each other in the gear box 30. Thereby, the reaction force with respect to the steering of the handle 11 can be appropriately changed by the reaction force motor 31. A position sensor 32 is coupled to the rotor rotation shaft 31R of the reaction force motor 31 in order to detect the steering angle of the handle 11. Further, a torque sensor 33 for detecting a load torque applied to the steering shaft 12, that is, a steering reaction force with respect to the operation of the handle 11 is provided at an intermediate portion of the steering shaft 12.

  Now, the rotor rotating shaft 31R of the reaction force motor 31 passes through the position sensor 32 and is connected to the mechanical rectifier 35 according to the present invention. As shown in FIG. 5, the mechanical rectifier 35 includes a brush holder 36 and a commutator 37 that rotate relative to each other. The commutator 37 includes a columnar base portion 38, and, for example, nine segments 39U, 39V, 39W,... Are equally arranged and fixed to the outer peripheral surface on one end side of the base portion 38. . Further, three output lines 40U, 40V, and 40W are led out from the end surface of the commutator 37 opposite to the base portion 38. The three segments 39U, 39U, 39U are commonly connected to the output line 40U, the other three segments 39V, 39V, 39V are commonly connected to the output line 40V, and the remaining three segments 39W, 39W, 39W are further connected. Are commonly connected to the output line 40W. Further, as shown in FIG. 6A, these segments are arranged in the order of segments 39U, 39V, 39W, 39U, 39V, 39W, 39U, 39V, 39W along the clockwise direction of FIG. ing. Note that the commutator 37 is fixed to the vehicle body and is not moved by the operation of the handle 11.

  On the other hand, the brush holder 36 has a cylindrical shape with a bottom that covers the periphery of the commutator 37, and the rotor rotation shaft 31 </ b> R described above is connected to a rotation input shaft 36 </ b> J extending from the center of the end surface of the brush holder 36. A bearing 37 </ b> J is fitted between the brush holder 36 and the commutator 37, so that the brush holder 36 can rotate while being centered with respect to the commutator 37.

  On the inner peripheral surface of the brush holder 36, a pair of brushes 41 and 42 that can slide on the outer peripheral surface of the commutator 37 are provided. These brushes 41 and 42 have a structure in which sliding members 41C and 42C are provided at the tips of elastic members 41B and 42B (for example, coil springs) that protrude from the inner peripheral surface of the brush holder 36, and the elastic members 41B and 42B are elastic. The force is pressed against the outer peripheral surface of the commutator 37.

  As shown in FIG. 6A, both the brushes 41 and 42 are arranged on the inner peripheral surface of the brush holder 36 with an interval of 180 degrees. The width of each brush 41, 42 (see L1 in the figure) is larger than the interval (see L3 in the figure) between adjacent segments 39U, 39V (39V, 39W, or 39W, 39U) and It is set smaller than the width of each segment 39U, 39V, 39W (see L2 in the figure). Further, when one of the brushes 41, 42 contacts any two of the segments 39U, 39V, 39W, the other of the brushes 41, 42 is the remaining one of the segments 39U, 39V, 39W. To come into contact.

  By adopting such a configuration, the brush holder 36 can have a simple structure as compared with the case where both the brushes 41 and 42 are arranged asymmetrically.

  As shown in FIG. 5, a pair of sliding rings 41 </ b> S and 42 </ b> S are laid on the outer peripheral surface of the brush holder 36. The brush 41 is electrically connected to the sliding ring 41S, and the brush 42 is electrically connected to the sliding ring 42S. Further, for example, a cover 43 is provided so as to cover the periphery of the brush holder 36. The cover 43 has a cylindrical shape with one end, and the bottom wall is fixed to the end exposed from the brush holder 36 in the commutator 37. A pair of power supply brushes 41T and 42T are provided on the inner peripheral surface of the cover 43, and these power supply brushes 41T and 42T are pressed against the sliding rings 41S and 42S. When the brush holder 36 rotates, the power supply brushes 41T and 42T are brought into sliding contact with the sliding rings 41S and 42S.

  Thus, in the present embodiment, the cover 43 surrounds the brush holder 36 and protects the contact portions between the power supply brushes 41T and 42T and the sliding rings 41S and 42S. A stable energization state can be ensured between the sliding rings 41S and 42S. Further, the contact portions between the brushes 41 and 42 and the segments 39U, 39V, 39W,... Are also covered and protected by the brush holder 36, so that a stable energized state can be ensured.

  The mechanical rectifier 35 is connected in parallel to the battery BT together with the motor drive control circuit 51 provided in the ECU 60 (see FIG. 1, where ECU is an abbreviation for Electric Control Unit). Here, as shown in FIG. 3, the motor drive control circuit 51 is a conventionally known FET three-phase bridge circuit. Specifically, three power supply lines 52 formed by push-pull connection of a pair of FETs 53 and 54 are provided, and an output for supplying power to the brushless motor 20 from a common connection part of both FETs 53 and 54 in each power supply line 52. Lines 55U, 55V, and 55W extend. One end side of the power supply line 52 is commonly connected to the brush 41 and the positive electrode of the battery BT, and the other end side is commonly connected to the brush 42 and the negative electrode of the battery BT.

  As shown in FIG. 5, in the mechanical rectifier 35, the positive electrode of the battery BT is connected to one power supply brush 41T, and the negative electrode of the battery BT is connected to the other power supply brush 42T. That is, as shown in FIG. 3, the brush 41 is connected to the positive electrode of the battery BT, and the brush 42 is connected to the negative electrode of the battery BT.

  As shown in the figure, the output lines 40U, 40V, 40W of the mechanical rectifier 35 and the output lines 55U, 55V, 55W of the motor drive control circuit 51 are both connected to the motor power switching device 46 ("motor" One of the output lines 40U, 40V, 40W (55U, 55V, 55W) is selectively connected to the phase circuits 24U, 24V, 24W of the brushless motor 20. It has become.

  Specifically, the output lines 40U, 40V, 40W of the mechanical rectifier 35 are connected to the phase circuits 24U, 24V, 24W of the brushless motor 20 via the B contact 44 provided in the motor power supply switching device 46, while the motor The output line of the drive control circuit 51 is connected to the phase circuits 24U, 24V, 24W of the brushless motor 20 via the A contact 45 provided in the motor power supply switching device 46. In a normal state, predetermined operating power is applied to the motor power supply switching device 46, the B contact 44 is turned off, and the A contact 45 is turned on. Further, when the ECU 60 and the position sensors 29 and 32 fail, no operating power is applied to the motor power switching device 46, the B contact 44 is turned on, and the A contact 45 is turned off.

  In the normal time described above, the ECU 60 controls the FETs 53 and 54 to be turned on and off by a conventionally known method, converts the direct current from the battery BT into a three-phase alternating current, and outputs the three-phase alternating current to each phase circuit 24U, 24V, 24W of the brushless motor 20. Shed. Thereby, the rotor 26 of the brushless motor 20 is rotationally driven. At this time, the ECU 60 executes the control program PG1 shown in FIG. 8 at a predetermined period, thereby controlling the rotational position of the brushless motor 20 according to the driving situation as will be described in detail later.

  On the other hand, at the time of the above-described failure, the mechanical rectifier 35 is connected between the brushless motor 20 and the battery BT, and the segments 39U, 39V, and 39W contacting the brushes 41 and 42 in conjunction with the operation of the handle 11 are connected. As will be described in detail later, the phase current flowing in the phase circuits 24U, 24V, 24W of the brushless motor 20 changes and the rotor 26 rotates. As a result, the steered wheels 50 are steered following the handle 11. The

The configuration of the present embodiment is as described above. Next, the function and effect of the present embodiment will be described.
When the automobile is started, operating power is applied from the ECU 60 to the motor power supply switching device 46, the B contact 44 is turned off, and the A contact 45 is turned on. That is, during normal operation, the motor drive control circuit 51 provided in the ECU 60 is electrically connected to the brushless motor 20, and the mechanical rectifier 35 is disconnected from the brushless motor 20. Then, the ECU 60 controls the rotational position of the brushless motor 20 by the motor drive control circuit 51 according to the driving situation by executing the control program PG1 shown in FIG. 8 at a predetermined cycle. Specifically, when the control program PG1 is executed, the ECU 60 takes in the detection results of the sensors such as the position sensors 29 and 32, the torque sensor 33, the vehicle speed sensor (not shown) (S1).

  Next, the ECU 60 determines the transmission ratio R between the steering wheel 11 and the steered wheels 50 according to the vehicle speed (S2). Here, when the steering angle of the steering wheel 11 is θ1 and the steering angle of the steered wheels 50 is θ2, the transmission ratio R described above is obtained from the following equation (1).

    R = θ2 / θ1 (1)

  Then, the ECU 60 acquires a predetermined transmission ratio R from the map 60M shown in FIG. 9 according to the vehicle speed. The map 60M 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.

  As shown in FIG. 8, the ECU 60 obtains the target turning angle of the steered wheels 50 from the determined transmission ratio R and the steered angle θ1 of the handle 11, and matches the steered angle of the steered wheels 50 with the target steered angle. The target rotation position of the brushless motor 20 for making it run is determined (S3). Then, a drive current corresponding to the deviation between the actual rotational position of the brushless motor 20 detected by the position sensor 29 and the target rotational position is supplied to the brushless motor 20 (S4).

  Next, the ECU 60 estimates the steering reaction force between the steered wheels 50 and the road surface based on the drive current necessary to steer the brushless motor 20 (S5). Then, the target steering reaction force of the handle 11 is determined with respect to the estimated steering reaction force (S6). 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 handle 11 is detected by the torque sensor 33, and a drive current is supplied to the reaction force motor 31 of the reaction force generator 13 so that the actual steering reaction force coincides with the target steering reaction force. The control program PG1 is exited (S7).

  With the above configuration, while the ECU 60 and the sensors 29 and 32 are operating normally, the turning performance of the vehicle is appropriately changed according to the driving conditions such as the vehicle speed, and the steering reaction force against the steering operation is also increased. It is changed appropriately.

  Now, when the ECU 60 or the position sensors 29 and 32 fail, it becomes impossible to steer the steered wheels 50 according to the handle 11. At this time, the operating power is no longer applied from the ECU 60 to the motor power supply switching device 46, the B contact 44 is turned on, and the A contact 45 is turned off. That is, at the time of failure, the motor drive control circuit 51 provided in the ECU 60 is disconnected from the brushless motor 20, and the mechanical rectifier 35 is electrically connected to the brushless motor 20.

  In this state, for example, when the handle 11 is rotated in one direction, the segments 39U, 39V, 39W contacting the brushes 41, 42 are switched as shown in the order of FIGS. 6 (A) to 6 (F). Then, as shown in FIG. 7, the phase voltages (Vu, Vv, Vw) and phase currents (Iu, Iv, Iw) applied to the phase circuits 24U, 24V, 24W are switched. Specifically, in the state shown in FIG. 6A, the positive brush 41 is in contact with the segment 39U, and the negative brush 42 is in contact with the segments 39V and 39W. As a result, as shown in FIG. 7A, the terminal side of the phase circuit 24U has the same potential as the positive brush 41, and the terminal side of the phase circuits 24V and 24W has the same potential as the negative brush 42. Then, as indicated by “U → V, W” in the lower column of FIG. 6A, a phase current flows from the U-phase circuit 24U to the V- and W-phase circuits 24V and 24W. The same applies to FIGS. 6B to 6F. In this way, when the handle 11 is rotated in one direction, the three-phase alternating current (Iu, Iv, Iw) shown in FIG. 7 is passed through the brushless motor 20 and the coils 23V-23W, 23u-23w The excitation state changes, and the rotor 26 rotates to follow this. Thereby, the steered wheel 50 is steered in one direction. Further, when the handle 11 is rotated in the reverse direction, the segments 39U, 39V, 39W contacting the brushes 41, 42 are switched in the reverse order as described above, thereby turning the steered wheels 50 in the reverse direction. Is done.

  As described above, according to the steer-by-wire system 10 of the present embodiment, even if the ECU 60 or each of the position sensors 29 and 32 fails during traveling, the steered wheels 50 are moved by the mechanical rectifier 35 according to the operation of the handle 11. It is possible to steer and evacuate the vehicle to the road shoulder. In addition, when the same configuration is simply provided in triplicate as in the prior art, all the triple configurations may be lost due to the same cause, but in the steer-by-wire system 10 of the present embodiment, In addition to the motor drive control circuit 51, a mechanical rectifier 35 having a configuration different from that of the motor drive control circuit 51 is provided. Therefore, it is unlikely that both the mechanical rectifier 35 and the motor drive control circuit 51 are lost. , Improve reliability. Furthermore, when the brushless motor 20 is driven by the mechanical rectifier 35, the detection results of the position sensors 29 and 32 are not required, so that the position sensors 29 and 32 do not need to have redundancy, and the installation space is reduced. (That is, it is excellent in mountability).

  Note that, for example, a configuration in which the rotor rotation shaft 26R provided in the brushless motor 20 and the handle 11 are connected by a flexible wire and the handle 11 and the rotor rotation shaft 26R are integrally rotated is possible. Further, by using the electric energy of the battery BT to cause the handle 11 to follow the brushless motor 20, the steering resistance of the handle 11 when turning the steered wheels 50, 50 can be reduced.

[Second Embodiment]
In the above embodiment, the mechanical rectifier 35 and the brushless motor 20 are provided separately, but in this embodiment, the mechanical rectifier 80 and the brushless motor 70 are integrated as shown in FIG. Yes. Hereinafter, only the configuration different from that of the first embodiment will be described, and the same configuration as that of the first embodiment will be denoted by the same reference numerals and redundant description will be omitted.

  A commutator 81 stands from the center of one end surface of the stator 71 provided in the brushless motor 70 of the present embodiment. The brush holder 36 is loosely fitted on the outside of the commutator 81 and is rotatably supported by a bearing 81B. Further, the stator 71 is provided with a cylindrical wall 72 so as to cover the brush holder 36, and power supply brushes 41 </ b> T and 42 </ b> T fixed to the cylindrical wall 72 are attached to the sliding rings 41 </ b> S and 42 </ b> S on the outer peripheral surface of the brush holder 36. It is pressed. Further, the rotation input shaft 36J of the brush holder 36 is connected to the rotor rotation shaft 31R of the reaction force motor 31 by a flexible wire (not shown) so that the brush holder 36 rotates in conjunction with the handle 11.

  .. Of the nine segments 39U, 39V, 39W,... Provided in the commutator 81 are connected in parallel to the phase circuits 24U, 24V, 24W of the brushless motor 70. Further, the electric power from the motor drive control circuit can be supplied to the common connection portion of the segments 39U, 39V, 39W,... And the phase circuits 24U, 24V, 24W. Is provided on the outer peripheral surface of the stator 71. Furthermore, a second connector 73 for connecting the power supply brushes 41T and 42T to the positive and negative electrodes of the battery is provided on the outer peripheral surface of the stator 71.

  In the present embodiment, a switch (not shown) normally disconnects the battery BT from the mechanical rectifier 80, and the brushless motor 70 is driven by the motor drive control circuit 51. When the motor drive control circuit 51 fails, the battery BT and the mechanical rectifier 80 are brought into conduction, and the brushless motor 70 is driven by the three-phase alternating current from the mechanical rectifier 80. Thereby, there exists an effect similar to 1st Embodiment.

[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 can be made without departing from the scope of the invention. It can be changed and implemented.

(1) In the above-described embodiment, the structure in which the mechanical rectifier 35 includes nine segments 39U, 39V, 39W,... Is illustrated, but the number of segments is not limited to nine.

(2) Further, the arrangement of the coils 23U, 23V, 23W,... In the brushless motor is not limited to the above embodiment.

(3) In the above embodiment, the motor power switching device 46 is provided between the mechanical rectifier 35 and the motor drive control circuit 51 and the brushless motor 20, but the mechanical rectifier 35 and the motor drive control circuit 51, You may make it the structure provided with the motor power supply switching device 46 between the batteries BT.

(4) In the above embodiment, the steering reaction force for the operation of the handle 11 is generated only by the reaction force motor 31. However, a midpoint return spring is attached to a portion interlocked with the handle 11 and the midpoint return spring is elastic. A configuration may be adopted in which the generated force is applied to the handle 11 as a steering reaction force.

(5) In the above embodiment, the steered wheel 50 is steered by engaging the rack 16 and the pinion 19, but as shown in FIG. 11, a ball screw mechanism passed between the steered wheels 50, 50. The present invention may be applied as a brushless motor according to the present invention in which the steered wheel 50 is steered by 90 and the ball screw member 91 of the ball screw mechanism 90 passes through the center.

(6) A plurality of brushless motors may be provided regardless of the rack and pinion type or the ball screw type.

(7) In the embodiment, the brush holder 36 of the mechanical rectifier 35 is connected to the handle 11 so as to be able to rotate together. However, the commutator 37 may be connected to the handle 11 so as to be able to rotate together.

(8) Although a battery is used in the embodiment, a power supply device may be used.

The conceptual diagram of the steer-by-wire system which concerns on 1st Embodiment of this invention. Cross section of brushless motor Circuit diagram of motor, motor drive control circuit and mechanical rectifier Perspective view of the structure around the handle Cross section of mechanical rectifier Sectional view showing the contact state between the brush and the segment Phase voltage applied to each phase circuit Flow chart of control program Conceptual map Sectional drawing of the motor and mechanical rectifier of 2nd Embodiment Conceptual diagram of steer-by-wire system with ball screw mechanism

Explanation of symbols

10 Steer-by-wire system 11 Handle 16 Rack 20, 70 Brushless motor 24U, 24V, 24W Phase circuit 35, 80 Mechanical rectifier 36 Brush holder 37, 81 Commutator 40U, 40V, 40W Output line 41, 42 Brush 41S, 42S Sliding ring 41T, 42T Power supply brush 42 Brush 43 Cover 44 B contact 45 A contact 46 Motor power switching device 50 Steering wheel 51 Motor drive control circuit

Claims (7)

A steering wheel and a steered wheel provided in the vehicle are mechanically separated from each other, a brushless motor is provided as a drive source for steering the steered wheel, and the brushless motor is driven by a motor drive control circuit according to a handle operation. In steer-by-wire system that steers steered wheels,
A plurality of segments connected to a plurality of phase circuits of the brushless motor;
A commutator having the plurality of segments fixed to the outer peripheral surface;
A brush holder that rotates relative to the commutator;
A mechanical rectifier comprising a pair of brushes fixed to the brush holder and connected to the positive and negative electrodes of the battery, slidably contacting the outer peripheral surface of the commutator and contacting any of the segments;
Either one of the brush holder or the commutator is coupled to the handle so as to be capable of interlocking rotation,
When normal, the mechanical rectifier is electrically disconnected from the battery or the brushless motor. When the motor drive control circuit fails, the motor rectifier is electrically connected to the battery and the brushless motor. A steer-by-wire system comprising means. The phase circuit consists of three phases: U phase, V phase, and W phase,
The segments are evenly arranged in the circumferential direction of the outer peripheral surface of the commutator,
The width of the brush is set larger than the interval between the adjacent segments and smaller than the width of each segment,
When one of the brushes comes into contact with the two adjacent segments of the U phase, V phase, or W phase, the other brush is in contact with the remaining one phase of the segment. The steer-by-wire system according to claim 1. With each odd pieces of the segments for each of the phase circuit, the U-phase, the V phase, to the gap of the segments adjacent the one or two phases of the W-phase, open 180 degrees in the circumferential direction of the commutator The steer-by-wire system according to claim 2 , wherein the remaining one-phase segment is disposed at a predetermined position.   The segment is provided with a total of nine segments, three for each U phase, V phase, and W phase. These nine segments are arranged along the circumferential direction of the commutator, such as U phase, V phase, W phase, U phase, The steer-by-wire system according to claim 3, wherein the steer-by-wire system is arranged in the order of V phase, W phase, U phase, V phase, and W phase.   5. The brush holder according to claim 1, wherein the brush holder has a cylindrical shape surrounding the commutator, and the pair of brushes are disposed on an inner peripheral surface of the brush holder. Steer-by-wire system. The brush holder is connected to rotate together with the handle,
On the outer peripheral surface of the brush holder, a pair of sliding rings connected to the brushes are laid,
The steer-by-wire system according to claim 5, further comprising a pair of power supply brushes that are slidably pressed against the sliding rings and connected to positive and negative electrodes of the battery.   The motor power supply switching means includes a B contact provided between the mechanical rectifier and the brushless motor or between the mechanical rectifier and the battery, the motor drive control circuit, and the brushless. The steer-by-wire system according to any one of claims 1 to 6, wherein the steer-by-wire system includes an A contact provided between the motor and the motor drive control circuit and the battery.

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