JP2005297877A - Vehicle steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect a state of an electric motor in a steer-by-wire type vehicle steering apparatus provided with at least two electric motors for turning steered wheels.
Immediately after the ignition switch is turned on, the first and second turning ECUs 36 and 37 have the driving forces in the normal state of the first and second turning electric motors 24 and 25 balanced and opposed to each other. In this way, a drive current is passed through the first and second steering electric motors 24 and 25. When the first and second steered electric motors 24 and 25 do not rotate, the normality of the first and second steered electric motors 24 and 25 is determined. When normality is not determined, rotation of the first and second steering electric motors 24 and 25 is stopped by gradually increasing the drive current of one of the first and second steering electric motors 24 and 25. At this time, it is determined whether the efficiency is reduced due to deterioration of the first or second electric motor 24 or 25 for turning.
[Selection] Figure 1

Description

  The present invention relates to a steer-by-wire vehicle steering apparatus including at least two electric motors for turning steered wheels or at least two electric motors for applying a steering reaction force to a steering handle.

Conventionally, two electric motors as a main steering actuator and a sub-steering actuator have been provided, and when both electric motors are normal, the steered wheels are steered by the rotation of both electric motors, and when one of the electric motors is abnormal A steer-by-wire vehicle steering apparatus that steers steered wheels by rotation of only the other electric motor is known (see Patent Document 1 below).
JP 2002-145098 A

  However, the above Patent Document 1 does not describe any method for detecting an abnormality of the electric motor.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a steer-by-wire vehicle steering apparatus having at least two electric motors for turning steered wheels or at least two electric motors for applying a steering reaction force to a steering handle. In other words, the state of the electric motor can be detected.

  In order to achieve the above object, a feature of the present invention is a steer-by-wire system including at least two electric motors for turning steered wheels or at least two electric motors for applying a steering reaction force to a steering handle. In the vehicle steering apparatus, a drive current is supplied to the two electric motors so that the driving forces of the two electric motors oppose each other, and the two electric motors rotate and non-rotate. The determination means for determining the state is provided. In this case, the timing when the drive current is supplied to the two electric motors is, for example, immediately after the ignition switch is turned on.

  The generated driving force of the electric motor depends on the magnitude of the driving current depending on the characteristics of the electric motor. Therefore, as in the present invention, if a driving current is passed through the two electric motors so that the driving forces of the two electric motors oppose each other, one electric motor tries to rotate the other electric motor relative to each other. To do. In this state, if the rotation and non-rotation of the two electric motors are observed, an abnormality occurs in one of the two electric motors and no driving force is generated, or the efficiency of the one electric motor decreases. That is, it is possible to easily determine the state of the electric motor.

  More specifically, the determination means includes, for example, a rotation detection means for detecting the rotation of two electric motors, and the same two so that the driving forces in a normal state of the two electric motors are balanced and opposed to each other. When rotations of the two electric motors are not detected by the rotation detection means in a state where a predetermined drive current predetermined according to the characteristics of the electric motors is supplied to the two electric motors, the normality of the two electric motors is normal. It is good to comprise with the 1st determination means which determines.

  If there is no abnormality in the two electric motors or the two electric motors are not deteriorated, the driving forces generated by the two electric motors are balanced, so the two electric motors do not rotate. Therefore, the normality of the two electric motors is easily determined by the first determination means. In addition, when the two electric motors are judged to be normal, the steered wheels are not steered or the steering handle is not rotated, so that the driver does not feel uncomfortable.

  Further, when the determination unit further determines that the normality of the two electric motors is not determined by the first determination unit, the magnitude of the drive current to at least one of the electric motors is different so that a difference occurs in the current flowing through the two electric motors. It can be configured to include a second determination unit that determines the state of the two electric motors based on detection of rotation of the two electric motors by the rotation detection unit. In this case, the second determination unit may change the magnitude of the drive current to at least one of the electric motors so that the difference between the currents flowing through the two electric motors gradually increases. Further, the second determination means includes a function of determining a reduction efficiency of one of the electric motors according to a difference between currents flowing through the two electric motors when rotation of the two electric motors is not detected by the rotation detection means. It is good to make it.

  If one of the two electric motors has not become inoperable, but simply deteriorates and cannot generate sufficient driving force, the drive current of the one electric motor is reduced to the other. If it is larger than the driving current for the electric motor, the driving forces of the two electric motors balance each other and the rotation of the two electric motors stops. Therefore, the second determination means can also easily determine a decrease in the efficiency of one of the electric motors.

  A vehicle steering apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a steering apparatus for a vehicle according to the embodiment.

  This vehicle steering device employs a steer-by-wire system in which a steering operation device 10 operated by a driver and a steering device 20 that steers the left and right front wheels FW1 and FW2 by operation of the driver are mechanically separated. doing. The steering operation device 10 includes a steering handle 11 as an operation unit that is rotated by a driver. The steering handle 11 is fixed to the upper end of the steering input shaft 12, and the steering input shaft 12 is rotationally driven at the lower end thereof by a reaction force generating steering reaction force electric motor 13 incorporating a speed reduction mechanism. .

  The steering device 20 includes a steering shaft 21 that extends in the left-right direction of the vehicle. Left and right front wheels FW1, FW2 as steered wheels are connected to both ends of the steered shaft 21 via tie rods 22a, 22b and knuckle arms 23a, 23b so as to be steerable. The left and right front wheels FW1 and FW2 are steered left and right by the displacement of the steered shaft 21 in the axial direction. On the outer periphery of the turning shaft 21, a first turning electric motor 24 and a second turning electric motor 25 assembled in a housing (not shown) are provided. The rotations of the first turning electric motor 24 and the second turning electric motor 25 are decelerated by the screw feed mechanisms 26 and 27 and converted into displacements in the axial direction of the turning shaft 21. The characteristics of the first and second steering electric motors 24, 25, that is, the characteristics of the magnitude of the generated driving force with respect to the magnitude of the driving current may be the same or different.

  Next, the electric control device 30 that controls the rotation of the steering reaction force electric motor 13, the first turning electric motor 24, and the second turning electric motors 24, 25 will be described. The electric control device 30 includes a steering angle sensor 31, a turning angle sensor 32, and first and second rotation angle sensors 33 and 34. The steering angle sensor 31 is assembled to the steering input shaft 12, detects the rotation angle from the neutral position of the steering handle 11, and outputs it as the steering angle θ. The turning angle sensor 32 is assembled on a housing (not shown) on the outer periphery of the turning shaft 21, detects the amount of axial displacement from the reference position of the turning shaft 21, and outputs it as the turning angle δ. The steering angle θ and the turning angle δ are represented by setting the neutral position to “0”, the right angle as a positive value, and the left direction as a negative value. The first and second rotation angle sensors 33 and 34 are assembled to the first and second electric motors 24 and 25, respectively, and the first and second rotation angles from the reference position of the first and second electric motors 24 and 25 are respectively. θm1 and θm2 are detected. Note that the first and second rotation angles θm1 and θm2 also indicate the rotation direction from the reference position by using positive and negative signs.

  Further, the electric control device 30 includes a steering reaction force electronic control unit (hereinafter referred to as a steering reaction force ECU) 35 connected to the steering angle sensor 31, a steering angle sensor 31, a turning angle sensor 32, and a first rotation. The first steering electronic control unit (hereinafter referred to as the first steering ECU) 36 connected to the angle sensor 33, the steering angle sensor 31, the steering angle sensor 32, and the second rotation angle sensor 34. A second steering electronic control unit (hereinafter referred to as a second steering ECU) 37. Each of these ECUs 35 to 37 has a microcomputer composed of a CPU, a ROM, a RAM and the like as main components. These three ECUs 35 are connected to each other and communicate various operations.

  The steering reaction force ECU 35 repeatedly executes the steering reaction force control program of FIG. 2 stored in the ROM every predetermined short time, and drives and controls the steering electric motor 13 via the drive circuit 41. The first turning ECU 36 executes the first check program of FIG. 3 stored in the ROM only once immediately after the ignition switch is turned on, and determines the state of the first turning electric motor 24. Further, the first steering ECU 36 then repeatedly executes the steering control program of FIG. 5 stored in the ROM every predetermined short time, and the first steering electric motor 24 is driven via the drive circuit 42. Drive control. The second turning ECU 37 executes the second check program of FIG. 4 stored in the ROM only once immediately after the ignition switch is turned on, and determines the state of the second turning electric motor 25. Further, the second turning ECU 37 then repeatedly executes the turning control program of FIG. 5 stored in the ROM every predetermined short time, and the second turning electric motor 25 is driven via the drive circuit 43. Drive control. Instead of providing the three ECUs 35 to 37, the respective controls may be appropriately performed by one or two ECUs.

  The drive circuits 41 to 43 are controlled by the ECUs 35 to 37 to drive and control the electric motors 13, 24, and 25. In these drive circuits 41 to 43, drive current sensors 41a to 43a that respectively detect drive currents flowing through the electric motors 13, 24, and 25 are provided, and the drive detected by the drive current sensors 41a to 43a is provided. The electric current is supplied to the ECUs 35 to 37, respectively. The ECUs 36 and 37 are connected to an alarm device 44 such as an alarm lamp and an alarm buzzer for warning the driver of an abnormality in the electric motor 24.

  Next, the operation of the embodiment configured as described above will be described. Immediately after the ignition switch (not shown) is turned on, the first and second steering ECUs 36 and 37 execute the first check program of FIG. 3 and the second check program of FIG. 4 only once.

  The execution of the first check program is started in step S20, and the first steering ECU 36 inputs the drive current detected by the drive current sensor 42a in step S21 and uses the input drive current. Then, the drive circuit 42 is controlled, and a drive current I1 is supplied to the electric motor 24 so as to rotate the first steering electric motor 24 in the first direction. The execution of the second check program is started in step S40, and the second steering ECU 37 inputs the drive current detected by the drive current sensor 43a in step S41 and uses the input drive current. Then, the drive circuit 43 is controlled, and a drive current I2 is supplied to the electric motor 25 so as to rotate the second steering electric motor 25 in the second direction.

  In this case, the first and second directions are rotation directions opposite to each other, that is, rotation directions for driving the steered shaft 21 in opposite directions. The drive currents I1 and I2 are the first and second steering electric motors 24 so that the generated driving forces of the first and second steering electric motors 24 and 25 in the normal state are balanced with each other. , 25 in accordance with the characteristics of the generated driving force with respect to 25 driving currents. That is, if the characteristics of the generated driving force with respect to the driving current of the first and second turning electric motors 24 and 25 are equal (for example, the first and second turning electric motors 24 and 25 are the same electric motor). If they are configured), the drive currents I1 and I2 are equal to each other. If the characteristics of the generated driving force with respect to the driving current of the first and second steering electric motors 24 and 25 are different, the driving currents I1 and I2 are different from each other.

  After the process of step S21, the first turning ECU 36 inputs the first rotation angle θm1 detected by the rotation angle sensor 33 in step S22, and whether or not the first turning electric motor 24 has rotated. Determine whether. On the other hand, after the processing in step S41, the second turning ECU 37 inputs the second rotation angle θm2 detected by the rotation angle sensor 34 in step S42, and the second turning electric motor 25 is rotated. It is determined whether or not.

  If the first and second steered electric motors 24 and 25 are normal, the first and second steered electric motors 24 and 25 have the driving force balanced with each other and the other electric motors 25 and 24. Therefore, the first and second turning electric motors 24 and 25 do not rotate. Even if the driving forces generated by the first and second steered electric motors 24 and 25 do not match very accurately, if the driving forces substantially match, the first and second components are caused by friction loss between the components. The second steering electric motors 24 and 25 do not rotate. Therefore, in this case, the first steering ECU 36 determines “No” in step S22, and stops the supply of the drive current to the first steering electric motor 24 in step S32, thereby controlling the first. The drive control of the one-turn electric motor 24 is canceled. Then, the end of the first check program is notified to the second steering ECU 37 in step S33, and the execution of the first check program is ended in step S34. On the other hand, the second steering ECU 37 determines “No” in step S42, and stops the supply of drive current to the second steering electric motor 25 in step S52, thereby controlling the second steering electric motor. The drive control of the motor 25 is released. In step S53, the first steering ECU 36 is notified of the end of the second check program, and in step S54, the execution of the first check program is ended.

  After the completion of the first and second check programs, the first and second steering ECUs 36 and 37 start to repeatedly execute the steering control program of FIG. 5 every predetermined short time. The execution of these steering control programs is started in step S60, and the first and second steering ECUs 36 and 37 respectively input the steering angle θ detected by the steering angle sensor 31 in step S61. At the same time, the turning angle δ detected by the turning angle sensor 32 is input.

  Next, in step S62, the first and second steering ECUs 36 and 37 refer to a target turning angle table prepared in advance in each ROM, and perform the target turning corresponding to the input steering angle θ. The steering angle δ * is calculated. As shown in FIG. 6, this target turning angle table stores a target turning angle δ * whose absolute value increases as the absolute value | θ | of the steering angle θ increases. Instead of using the target turning angle table, a function in which the relationship between the steering angle θ and the target turning angle δ * is predetermined is prepared, and the input steering angle θ is input using the same function. The target turning angle δ * corresponding to may be calculated. In addition, a vehicle speed sensor, a yaw rate sensor, a lateral acceleration sensor, and the like may be provided to correct the calculated target turning angle δ * according to the vehicle speed, yaw rate, lateral acceleration, and the like detected by the sensors. .

  After the calculation of the target turning angle δ *, the first and second turning ECUs 36 and 37 drive and control the first and second turning electric motors 24 and 25 in step S63, and the process proceeds to step S64. The execution of the steering control program is once terminated. In the process of step S63, a difference δ * -δ between the calculated target turning angle δ * and the inputted turning angle δ is calculated, and in cooperation with the drive circuits 42 and 43, the first and The second steering electric motors 24 and 25 are driven and controlled so that the difference δ * −δ is “0”. Accordingly, the first and second steering electric motors 24 and 25 drive the steering shaft 21 in the axial direction via the screw feed mechanisms 26 and 27 by their rotation. The left and right front wheels FW1 and FW2 are steered to the target turning angle δ * by the displacement of the turning shaft 21 in the axial direction. As a result, the left and right front wheels FW1, FW2 are steered according to the turning operation of the steering handle 11, and the vehicle is turned left and right.

  In parallel with the execution of the steering control program, the steering reaction force ECU 35 repeatedly executes the steering reaction force control program of FIG. 2 every predetermined short time. Execution of this steering reaction force program is started in step S10, and the steering reaction force ECU 35 inputs the steering angle θ detected by the steering angle sensor 31 in step S11.

  Next, the steering reaction force ECU 35 refers to the target steering reaction force table and calculates a target steering reaction force corresponding to the input steering angle θ. As shown in FIG. 7, the target steering reaction force table stores a target steering reaction force whose absolute value increases as the absolute value | θ | of the steering angle θ increases. Instead of using the target steering reaction force table, a function in which the relationship between the steering angle θ and the target steering reaction force is predetermined is prepared, and the function is used to correspond to the input steering angle θ. The target steering reaction force to be calculated may be calculated. In this case, the target steering reaction force may be corrected according to the vehicle speed, the yaw rate, the lateral acceleration, and the like.

  After the calculation of the target steering reaction force, the reaction force torque applied to the steering handle 11 is matched with the calculated target steering reaction force using the drive current detected by the drive current sensor 41a in step S13. In addition, the rotation of the steering reaction force electric motor 13 is controlled via the drive circuit 41. And in step S14, execution of this steering control program is once complete | finished. Thus, a reaction torque corresponding to the steering angle θ of the steering handle 11, that is, the turning angle δ of the left and right front wheels FW1 and FW2, is applied to the turning operation of the steering handle 11 by the driver. Therefore, the driver can turn the steering handle 11 while feeling the steering reaction force.

  Next, a case where one of the first and second steering electric motors 24 and 25 is not normal will be described. In this case, unlike the case described above, one of the first and second steering electric motors 24 and 25 rotates the other, so the first and second steering electric motors 24 and 25 are Rotate together. Therefore, it is determined as “Yes” in Step S22 of FIG. 3, the first steering ECU 36 proceeds to Step S23, and the first steering electric motor 24 is in the direction opposite to the first direction (that is, the second direction). It is determined whether it is rotating. The rotation of the first steering electric motor 24 in the direction opposite to the first direction means that the first steering electric motor 24 is rotated by the second steering electric motor 25. On the other hand, the second steering ECU 37 determines “Yes” in step S42, and in step S43, the second steering electric motor 25 rotates in the direction opposite to the second direction (that is, the first direction). It is determined whether or not. The rotation of the second turning electric motor 25 in the direction opposite to the second direction means that the second turning electric motor 25 is rotated by the first turning electric motor 24.

  If the first steered electric motor 24 rotates in the direction opposite to the first direction, the first steered ECU 36 determines “Yes” in step S23, and executes the processes in and after step S24. On the other hand, in this case, the second steered electric motor 25 also rotates in the direction opposite to the first direction, that is, in the second direction, so the second steered ECU 37 determines “No” in step S43, and the step In S51, a notification of the end of the first check program from the first steering ECU 36 is awaited. During this time, the second steering electric motor 25 is continuously supplied with the drive current I2 that has been passed through the process of step S41.

  After first setting the variable n to “1” in step S24, the first steering ECU 36 performs the variable n count-up process in step S27 and the variable n comparison process in step S28 to set the variable n to a predetermined value N. Until this is the case, the circulation process consisting of steps S25 to S28 is repeatedly executed. Note that the predetermined value N is a predetermined natural number, and the larger the value, the greater the number of times of circulation processing consisting of steps S25 to S28. During the circulation repair, the drive current that flows to the first steering electric motor 24 is increased by a minute current ΔI by the process of step S25. In the state in which the drive current is increased by the process of step S26, the detection first rotation angle θm1 from the rotation angle sensor 33 is input, and the first turning electric motor 24 rotates in the direction opposite to the first direction. Detect whether you are doing. In other words, it is determined whether the first steered electric motor 24 has stopped due to the increase in the drive current.

  If the first steered electric motor 24 continues to rotate in the direction opposite to the first direction, the drive current increasing process in step S25 is executed again, and then the determination process in step S26 is executed. If the first steering electric motor 24 does not rotate in the direction opposite to the first direction during the circulation process consisting of steps S25 to S28, it is determined as “No” in step S26, and the process proceeds to step S29. . In this state, when the driving current flowing through the first steering electric motor 24 is made larger by the increased current n · ΔI than the driving current flowing through the second steering electric motor 25, the first and second steering electric motors 24 are driven. This means that the driving forces of the electric motors 24 and 25 are balanced. In other words, it means that the efficiency of the first steering electric motor 24 is reduced by the increased current n · ΔI due to deterioration of the electric motor 24 or the like. In step S29, the fact that the efficiency of the first turning electric motor 24 is reduced is stored, and the increased current n · ΔI for the first turning electric motor 24 is stored. In addition, you may make it notify a driver | operator of the efficiency fall of this electric motor 24 for 1st steering.

  On the other hand, if the first steering electric motor 24 continues to rotate in the direction opposite to the first direction even when the variable n is equal to or greater than the predetermined value N, “Yes” is determined in step S28. The process proceeds to step S30. In this state, even if the drive current flowing through the first steering electric motor 24 is increased by (N−1) · ΔI (a somewhat larger current) than the drive current flowing through the second steering electric motor 25, This means that the driving forces of the first and second steering electric motors 24 and 25 are not balanced. In other words, it means that the first turning electric motor 24 is inoperable. In step S30, the alarm device 44 is operated to notify the driver that an abnormality has occurred in the first steering electric motor 24.

  After the process of step S29 or step S30, the first steering ECU 36 releases the drive control of the first steering electric motor 24 in step S32, and the first check is made to the second steering ECU 37 in step S33. The end of the program is notified, and the execution of the first check program is ended in step S34.

  Upon notification of the end of the first check program, the second steering ECU 37 determines “Yes” in step S51 of FIG. 4 and cancels the drive control of the second steering electric motor 25 in step S52. After executing the process and the notification process to the first steering ECU 36 in step S53, the execution of the second check program is terminated in step S54.

  Next, a case where the first steering electric motor 24 rotates in the first direction will be described. In this case, the first steering ECU 36 determines “No” in step S23 of FIG. 3 and waits for notification of the end of the second check program from the second steering ECU 37 in step S31. During this time, the drive current I1 that has been passed through the process of step S21 continues to flow through the first turning electric motor 24. In this case, since the second steering electric motor 25 rotates in the first direction, that is, the direction opposite to the second direction, the second steering ECU 37 determines “Yes” in step S43 of FIG. It determines and performs the process of step S44-S50.

  The processing of these steps S44 to S50 is similar to the processing of steps S24 to S30 of FIG. 3 described above, and the difference is that the object is the second turning electric motor 25 and the determination processing of step S46. Since only the rotation in the direction opposite to the second direction is determined at, the detailed description thereof is omitted. After the processing of steps S44 to S50, the second steering ECU 37 releases the drive control of the second steering electric motor 25 in step S52, and the second steering ECU 36 receives the second steering ECU 36 in step S53. The end of the check program is notified, and the execution of the second check program is ended in step S54.

  Upon notification of the end of the second check program, the first steering ECU 36 determines “Yes” in step S31 of FIG. 3 and cancels the drive control of the first steering electric motor 24 in step S32. After executing the process and the notification process to the second steering ECU 37 in step S33, the execution of the first check program is terminated in step S34.

  When the execution of the first and second check programs is completed in this way, the first and second steering ECUs 36 and 37 execute the steering control program shown in FIG. Steering control is performed on FW1 and FW2. In this case, when the efficiency of the first steering electric motor 24 is lowered, in the steering control process of step S63, a drive current that is large by an amount corresponding to the stored increased current n · ΔI is set to the first. The first and second steering electric motors 24 and 25 are caused to generate an equal driving force so as to be supplied to the steering electric motor 24 to compensate for a decrease in efficiency. When the efficiency of the second turning electric motor 25 is reduced, in the turning control process of step S63, a driving current that is larger by the amount corresponding to the stored increased current n · ΔI is supplied to the second turning electric motor 25. The first and second steering electric motors 24 and 25 are caused to generate an equal driving force so as to flow into the rudder electric motor 25 to compensate for a decrease in efficiency.

  As can be understood from the above operation description, according to the above embodiment, the first and second steering electric motors in the normal state are obtained by the processes of steps S21 and S22 of FIG. 3 and steps S41 and S42 of FIG. A driving current in which the driving forces 24 and 25 are balanced and opposed is supplied to the first and second turning electric motors 24 and 25 to determine the normal state of the first and second turning electric motors 24 and 25. Thus, the normality of the first and second steering electric motors 24 and 25 is easily determined. At the time of this normal determination, the first and second steering electric motors 24 and 25 do not rotate and the left and right front wheels FW1 and FW2 are not steered, so the driver does not feel uncomfortable. .

  Further, the processes in steps S23 to S29 in FIG. 3 and steps S43 to S49 in FIG. 4 cause a difference in the current flowing in the first and second steering electric motors 24 and 25, so that the first and second Since the efficiency reduction and inoperability of the first and second steering electric motors 24 and 25 are determined by the rotation of the steering electric motors 24 and 25, it is possible to easily detect these efficiency reductions and inoperability. . In particular, when the difference between the currents flowing through the first and second steering electric motors 24 and 25 is gradually increased and the rotation of the first and second steering electric motors 24 and 25 stops, Since the reduced efficiency of the first and second steering electric motors 24 and 25 is quantitatively measured in accordance with the difference in current, the amount of reduced efficiency can be easily detected, and thereafter This reduced efficiency can be used for control.

  Furthermore, in carrying out the present invention, the present invention is not limited to the above embodiment and its modifications, and various modifications can be made without departing from the object of the present invention.

  For example, in the above-described embodiment, the efficiency reduction of the first and second steering electric motors 24 and 25 and the detection of inoperability are detected by increasing the drive current of the electric motor on the side rotated by the other electric motor. I did it. However, instead of this, the drive current of the electric motor on the side where the other electric motor is rotated is gradually decreased, so that the first or second steering electric motors 24, 25 corresponding to the other electric motor are used. It may also be possible to detect a decrease in efficiency and inoperability.

  In this case, in the first check program shown in FIG. 3, it is determined in steps S23 and S26 whether or not the first steering electric motor 24 has rotated in the first direction, and in step S25, the first rotation is performed. The drive current of the rudder electric motor 24 is decreased by a minute current ΔI. In this case, in the first check program, since the efficiency reduction and inoperability of the second turning electric motor 25 are detected, it is necessary to output the detection result to the second turning ECU 37. There is. On the other hand, in the second check program of FIG. 4, it is determined whether the second steering electric motor 25 has rotated in the second direction in steps S43 and S46, and the second steering in step S45. The drive current of the electric motor 25 is decreased by a minute current ΔI. In this case, in the second check program, since the efficiency reduction and inoperability of the first turning electric motor 25 are detected, it is necessary to output the detection result to the first turning ECU 36. There is.

  In addition, the efficiency reduction and inoperability detection of the first and second steering electric motors 24 and 25 are detected, and the drive current of one of the first and second steering electric motors 24 and 25 is detected. The drive current of the other electric motor may be decreased by the minute current ΔI while increasing by the minute current ΔI. In this case, the drive current of the electric motor on the side rotated by the other electric motor is increased as in the first and second check programs of FIGS. 3 and 4, and the other electric motor is rotated. The drive current of the electric motor on the side is reduced as in the modified example. However, the reduced efficiency of the electric motor in this case is twice that of the above embodiment and the modification.

  In the above embodiment, the rotations of the first and second steering electric motors 24 and 25 are detected by the first and second rotation angle sensors 33 and 34. However, since the rotation of the first and second steering electric motors 24 and 25 corresponds to the displacement of the steering shaft 21 and the steering of the left and right front wheels FW1 and FW2, the first and second steering electric motors. You may make it detect rotation of 24,25 using the detected turning angle (delta) by the turning angle sensor 32. FIG.

  In the above embodiment, the first and second steering electric motors 24 and 25 are used to steer the left and right front wheels FW1 and FW2. However, the present invention steers the left and right front wheels FW1 and FW2. Therefore, the present invention is also applied to a vehicle steering apparatus including three or more electric motors. In this case, for example, as shown in FIG. 8, the vehicle steering apparatus can be modified. In this modified example, the turning shaft 21 is configured by a rack bar, and in addition to the configuration of the above-described embodiment, a turning input in which a pinion gear 51 that meshes with the rack teeth 21 a provided on the turning shaft 21 is fixed to the lower end. It has a shaft 52. A third turning electric motor 53 is provided at the upper end of the turning input shaft 52 so that the rotation of the third turning electric motor 53 is transmitted to the turning input shaft 52 via the speed reducer 54. .

  Further, in this modification, a drive circuit 56 incorporating a third steered ECU 55 similar to the first and second steered ECUs 36 and 37 and a drive current sensor 56a similar to the drive circuits 42 and 43 is incorporated. And a rotation angle sensor 57 for detecting the rotation angle θm3 of the third steering electric motor 53 similar to the first and second rotation angle sensors 33 and 34. Further, in order to detect the turning angle δ of the left and right front wheels FW1 and FW2, the turning angle sensor 32 of the above embodiment can be used, but the rotation angle from the reference position of the turning input shaft 52 is detected. Thus, a turning angle sensor 58 that detects the turning angle δ can be used.

  The third turning ECU 55 is connected to the steering reaction force ECU 35, the first and second turning ECUs 36 and 37, and is similar to the first and second check programs of FIGS. 3 and 4 described above. The configured third check program is executed, and the steering control program of FIG. 5 is executed. In this case, the first to third steering ECUs 36, 37, and 55 simultaneously execute the two check programs of the first to third check programs, whereby the first to third steering electric motors 24 are operated. 25, 53, normal state, efficiency reduction state and inoperable state are detected. Specifically, first, as in the above-described embodiment, the first and second turning ECUs 36 and 37 execute the first and second check programs, and the first and second turning electric motors 24, 25 states are determined. Thereafter, the third turning ECU 55 and the first turning ECU 36 (or the second turning ECU 37) simultaneously execute the third check program and the first check program (or the second check program), respectively. The states of the turning electric motor 53 and the first turning electric motor 24 (or the second turning electric motor 25) are determined. In this case, the first to third steering ECUs 36, 37, and 55 are turned in FIG. 5 after all the state determinations of the first to third steering electric motors 24, 25, and 53 are completed. Start running each rudder control program.

  Moreover, in the said embodiment and modification, this invention was applied with respect to the several electric motors 24, 25, 53 for steering provided in the steering apparatus of a vehicle. However, one or a plurality of steering reaction force electric motors for applying a steering reaction force to the turning operation of the steering handle 11 in the steering apparatus of the vehicle is the steering reaction force electric motor 13 of the above embodiment. In addition to the above, the present invention is also applied to a plurality of steering reaction force electric motors including the steering reaction force electric motor 13 of the above embodiment. The one or more steering reaction force electric motors are provided in parallel or in series with the steering reaction force electric motor 13 as long as the reaction force can be applied to the turning operation of the steering handle 11. It may be.

  In this modification, a steering reaction force ECU (including the steering reaction force ECU 35 of the above embodiment) that controls the above-described plurality of steering reaction force electric motors independently or in common via a drive circuit, The first and second check programs configured in the same manner as the first and second check programs in FIGS. 3 and 4 of the above embodiment are executed only once immediately after the ignition switch is turned on. In the first and second check programs, instead of the first to third steering electric motors 24, 25, 53, the drive control of the plurality of steering reaction force electric motors described above is performed, and their rotations are controlled. Is detected. Therefore, rotation angle sensors similar to the rotation angle sensors 26, 27, and 57 of the above-described embodiment are respectively assembled to the plurality of steering reaction force electric motors.

  Also according to this modification, normality of a plurality of steering reaction force electric motors in a normal state is easily determined by executing the program. In the normal determination, the plurality of steering reaction force electric motors do not rotate and the steering handle 11 does not rotate, so that the driver does not feel uncomfortable.

  Also in this modified example, as in the above-described embodiment, a difference occurs in the currents flowing through the plurality of steering reaction force electric motors, and the plurality of steering reaction forces are rotated by the rotation of the plurality of steering reaction force electric motors. It is preferable to determine whether the efficiency of the force electric motor is reduced or not. In this case as well, the difference between the currents that flow through the plurality of steering reaction force electric motors is gradually increased, and one or more of the steering reaction force electric motors is selected. When the rotation stops, the reduced efficiency of the plurality of steering reaction force electric motors may be measured quantitatively according to the difference in current. According to these, the same effect as that of the above-described embodiment is expected for a plurality of steering reaction force electric motors.

  Furthermore, in the above embodiment, the steering handle 11 that is turned to steer the vehicle is used. However, instead of this, for example, a joystick-type steering handle that is linearly displaced may be used, or any other one that can be operated by the driver and instructed to steer the vehicle is used. May be.

1 is a schematic view of a vehicle steering apparatus according to an embodiment of the present invention. It is a flowchart of the steering reaction force control program executed by the steering reaction force ECU of FIG. It is a flowchart of the 1st check program performed by ECU for 1st steering of FIG. It is a flowchart of the 2nd check program performed by ECU for 2nd steering of FIG. It is a flowchart of the steering control program performed by the ECU for 1st and 2nd steering of FIG. It is a graph which shows the relationship between a steering angle and a target turning angle. It is a graph which shows the relationship between a steering angle and a target steering reaction force. It is the schematic of the steering apparatus of the vehicle which concerns on the modification of FIG.

Explanation of symbols

FW1, FW2 ... front wheels, 10 ... steering operation device, 11 ... steering handle, 13 ... electric motor for steering reaction force, 20 ... steering device, 21 ... steered shaft, 24, 25, 53 ... electric motor for steering, 26, 27, 57 ... rotation angle sensor, 31 ... steering angle sensor, 32, 58 ... steering angle sensor, 35 ... steering reaction force ECU, 36, 37, 55 ... steering ECU, 41a, 42a, 43a, 56a ... Drive current sensor

Claims (5)

In a steer-by-wire vehicle steering apparatus including at least two electric motors for turning steered wheels or at least two electric motors for applying a steering reaction force to a steering handle,
A determination means for determining a state of the two electric motors by rotating and non-rotating the two electric motors by causing a driving current to flow through the two electric motors so that the driving forces of the two electric motors oppose each other. A vehicle steering apparatus characterized by comprising: In the vehicle steering apparatus according to claim 1,
The determination means;
Rotation detection means for detecting rotation of the two electric motors;
In a state where a predetermined drive current determined in advance according to the characteristics of the two electric motors flows in the two electric motors so that the respective driving forces in the normal state of the two electric motors are balanced and opposed to each other, A vehicle steering apparatus comprising: a first determination unit configured to determine whether the two electric motors are normal when rotation of the two electric motors is not detected by the rotation detection unit. In the vehicle steering apparatus according to claim 2,
The determination means further includes:
When the normality of the two electric motors is not determined by the first determination means, the magnitude of the drive current to at least one of the electric motors is changed so that a difference occurs in the currents flowing through the two electric motors. A vehicle steering apparatus comprising: second determination means for determining a state of the two electric motors based on detection of rotation of the two electric motors by a rotation detection means.   The vehicle steering apparatus according to claim 3, wherein the second determination unit changes a magnitude of a drive current to at least one of the electric motors so that a difference between currents flowing through the two electric motors gradually increases. The second determination unit includes a function of determining a reduction efficiency of one electric motor according to a difference between currents flowing through the two electric motors when rotation of the two electric motors is not detected by the rotation detection unit. The vehicle steering apparatus according to claim 3 or 4.

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