JP4594129B2 - Vehicle steering device - Google Patents

Description

  The present invention relates to a steer-by-wire vehicle steering apparatus in which a steering handle and steered wheels are mechanically separated.

Conventionally, for example, as shown in Patent Document 1 below, an input member that is connected to a steering handle and rotates in conjunction with the steering handle, and an output member that is connected to a steered wheel and steers the steered wheel by rotation. A steer-by-wire vehicle steering apparatus is known in which both are connected via a cable connecting the first and second clutches at both ends. In the vehicle steering apparatus, when the vehicle is operating normally, the first and second clutches are set to the disengaged state, and the input member is rotated by the first actuator according to the turning operation of the steering handle. A steering reaction force is applied to the steering handle in response to the turning operation of the steering handle, and the output member is rotated by the second actuator in accordance with the turning operation of the steering handle. To steer the steered wheels. On the other hand, when the steering device is abnormal, the first and second clutches are set to the connected state, the input member and the output member are mechanically coupled via the cable, and the turning operation of the steering handle is performed by the input member, The steered wheels are steered according to the turning operation of the steering handle so as to be transmitted to the steered wheels via the cable and the output member.
Japanese Patent Laid-Open No. 2004-224096

  In the vehicle steering apparatus configured as described above, in a normal state, the steering reaction force is applied to the steering handle by the first actuator, and the steered wheels are steered by the second actuator. Thus, even if one of the first and second clutches is set to the connected state due to the abnormality, the other clutch is in the disconnected state, so that the steering reaction force control by the first and second actuators is performed. And the steering control can be continued. However, on the other hand, as long as the steering device is kept normal, the cable will not rotate. This type of cable is generally installed in a flexible tube filled with grease. If the steering device is kept normal and the cable does not rotate for a long time, the cable will rotate due to deterioration of the grease. A large load is applied. In this case, when the first and second clutches are connected due to the occurrence of an abnormality in the steering device, and the rotation of the steering handle is switched to the mechanically connected state transmitted to the steered wheels via the cable, Therefore, the steering torque for rotating the steering handle becomes extremely large, and there is a possibility that the steered wheels cannot be smoothly turned according to the turning operation of the steering handle.

  The present invention has been made to cope with the above-described problems, and an object of the present invention is to provide a steering device for a steer-by-wire system using a cable such as that described above. An object of the present invention is to provide a vehicle steering apparatus that can smoothly steer steered wheels according to a turning operation of a steering handle even in a connected state.

  In order to achieve the above object, the present invention is characterized by an input member connected to a steering handle and displaced in conjunction with the steering handle, and connected to the input member so as to be able to transmit power and driving the input member. A first actuator that applies a reaction force to the steering operation of the steering wheel, an output member that is connected to the steered wheel and is displaced in conjunction with the steered wheel, and an output member that is connected to the output member so that power can be transmitted. A second actuator that steers the steered wheels by driving, a cable that is connected to the input member and the output member at both ends, and rotates in conjunction with the displacement of the input member and the output member, and the input member; A first clutch interposed between one end of the cable, a second clutch interposed between the other end of the cable and the output member, and selectively disconnecting the first and second clutches; When the first and second clutches are in the disengaged state, the first and second actuators are driven and controlled according to the turning operation of the steering handle so that the steering handle can be turned. In response, a steering reaction force is applied to the steering wheel, the steered wheels are steered, and when the first and second clutches are in the connected state, the displacement of the input member is transmitted to the output member via the rotation of the cable. When the first and second clutches are disengaged in the electric control device in the vehicle steering device including the electric control device that allows the turning of the steered wheels according to the turning operation of the steering handle. There is provided clutch control means for sporadically controlling only one of the first and second clutches into the connected state.

  In the feature of the present invention configured as described above, even if the first and second clutches are not set to the connected state by the electric control device due to an abnormality occurring in the vehicle steering device, the first Only one of the first and second clutches is connected sporadically. As a result, in a state where only one of the first and second clutches is connected, the cable rotates when the first or second actuator is operated, that is, when the input member or the output member is displaced. The rotation of the cable avoids an increase in steering torque due to grease deterioration or the like, so that even when the steering handle and the steered wheel are mechanically connected via the cable, the rotation according to the turning operation of the steering handle is performed. The steering wheel can always be steered smoothly.

  Further, the clutch control means may be, for example, a state immediately after the ignition switch is turned on, a state immediately after the ignition switch is turned off, a state where the vehicle is traveling at a low speed, and a rotation of the steering handle by the second actuator. At least in a state where the difference between the turning angle of the steered wheel according to the dynamic operation and the steered angle of the steered wheel steered via the cable according to the turning operation of the steering handle is equal to or less than a predetermined value Only one of the first and second clutches is sporadically controlled to the connected state on the condition that it is in any one state, that is, on the condition that the vehicle is in the specific state.

  As a result, when the state immediately after the ignition switch is turned on or the state immediately after the ignition switch is turned off is adopted as the specific state of the vehicle, the vehicle is stopped or almost stopped. Therefore, even if the other clutch is mistakenly set to the connected state and the input member and the output member are connected via the cable, the vehicle motion is not greatly affected, so the safety of the vehicle is ensured. The Further, even if the other clutch is erroneously connected as described above while the vehicle is traveling at a low speed, it does not affect the movement of the vehicle, so that the safety of the vehicle is ensured. Further, the difference between the turning angle of the steered wheel according to the turning operation of the steering handle by the second actuator and the turning angle of the steered wheel steered via the cable according to the turning operation of the steering handle is Even if the other clutch is erroneously connected as described above in a state where it is equal to or less than the predetermined value, the steered state of the steered wheels does not change before and after the other clutch is erroneously connected according to the turning operation of the steering handle. Therefore, the safety of the vehicle is ensured.

a. First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall schematic diagram of a vehicle steering apparatus according to the first embodiment.

  This vehicle steering device mechanically includes a steering operation device 10 that is steered by a driver, and a steering device 20 that steers left and right front wheels FW1 and FW2 as steered wheels according to the steering operation of the driver. A separate steer-by-wire system is used. 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 a steering reaction force electric motor (actuator) 13 is assembled to the lower portion of the steering input shaft 12. The steering reaction force electric motor 13 drives the steering input shaft 12 to rotate about the axis via the speed reduction mechanism 14. A conversion mechanism 15 is connected to the lower end of the steering input shaft 12. The conversion mechanism 15 includes a worm and a wheel. The conversion mechanism 15 speeds up rotation around the axis of the steering input shaft 12 and converts the rotation into rotation around an axis orthogonal to the axis and outputs the rotation. The steering input shaft 12 and the conversion mechanism 15 constitute an input member of the present invention.

  The steered device 20 includes a rack bar 21 that extends in the left-right direction of the vehicle. Left and right front wheels FW1, FW2 are connected to both ends of the rack bar 21 via a tie rod and a knuckle arm (not shown) so as to be steerable. The left and right front wheels FW1, FW2 are steered to the left and right by the displacement of the rack bar 21 in the axial direction. On the outer periphery of the rack bar 21, there is provided a steering electric motor (actuator) 22 assembled in a housing (not shown). The rotation of the steered electric motor 22 is decelerated by the screw feed mechanism 23 and is converted into an axial displacement of the rack bar 21.

  The steering device 20 also has a steering output shaft 24 that can rotate around the axis. A pinion gear 25 is fixed to the lower end of the steering output shaft 24. The pinion gear 25 meshes with rack teeth 21a provided on the rack bar 21, and the rack bar 21 is axially rotated by rotation around the axis of the steering output shaft 24. It is displaced to. A conversion mechanism 26 is connected to the upper end of the steering output shaft 24. The conversion mechanism 26 includes a worm and a wheel. The conversion mechanism 26 decelerates the rotation input about the axis orthogonal to the axis of the steering output shaft 24 and changes the rotation to the rotation about the axis of the steering output shaft 24 for output. The conversion mechanism 26, the steering output shaft 24, the pinion gear 25, and the rack bar 21 constitute the output member of the present invention.

  Between the conversion mechanisms 15 and 26, a cable 31 as an intermediate member is disposed. The cable 31 transmits the rotation of the output shaft of the conversion mechanism 15 to the input shaft of the conversion mechanism 26, and is arranged in the long flexible tube filled with grease along the axial direction of the tube. Yes. A first electromagnetic clutch 32 is disposed between the fixing member 31 a at the upper end of the cable 31 and the conversion mechanism 15. For example, the first electromagnetic clutch 32 is set in a disconnected state in an energized state to disconnect the cable 31 from the steering input shaft 12 and the conversion mechanism 15 so that power cannot be transmitted, and is set in a connected state in a non-energized state. 31 is connected to the steering input shaft 12 and the conversion mechanism 15 so that power can be transmitted. A second electromagnetic clutch 33 is disposed between the fixing member 31 b at the lower end of the cable 31 and the conversion mechanism 26. For example, the second electromagnetic clutch 33 is set in a disconnected state in an energized state to disconnect the cable 31 from the conversion mechanism 26 and the steering output shaft 24 so that power cannot be transmitted, and is set in a connected state in a non-energized state. 31, the conversion mechanism 26, and the steering output shaft 24 are coupled so that power can be transmitted.

  Next, the electric control device 40 that controls the steering reaction force electric motor 13, the steering electric motor 22, and the electromagnetic clutches 32 and 33 will be described. The electric control device 40 includes a steering angle sensor 41, a turning angle sensor 42, and a vehicle speed sensor 43. The steering angle sensor 41 is assembled to the steering input shaft 12 and measures the rotation angle around the axis of the steering input shaft 12 to detect the rotation angle from the neutral position of the steering handle 11 and outputs it as the steering angle θh of the steering wheel. To do. The steering wheel steering angle θh represents a neutral position of the steering wheel 11 as “0”, a right steering angle is represented by a positive value, and a left steering angle is represented by a negative value. The turning angle sensor 42 is mounted on the rack bar 21 and measures the axial displacement of the rack bar 21 to detect and output the actual turning angle δ of the left and right front wheels FW1, FW2. Note that the actual turning angle δ represents the rightward turning angle of the left and right front wheels FW1, FW2 as a positive value with the neutral position of the left and right front wheels FW1, FW2 being “0”, and the left direction of the left and right front wheels FW1, FW2 The steering angle of is expressed as a negative value. The vehicle speed sensor 43 detects and outputs the vehicle speed V.

  The electric control device 40 includes a clutch electronic control unit (hereinafter referred to as a clutch ECU) 44, a steering reaction force electronic control unit (hereinafter referred to as a steering reaction force ECU) 45, and a steering device. An electronic control unit (hereinafter referred to as a steering ECU) 46 is provided. A steering angle sensor 41 and a vehicle speed sensor 43 are connected to the clutch ECU 44. A steering angle sensor 41 and a vehicle speed sensor 43 are connected to the steering reaction force ECU 45. A steering angle sensor 41, a steering angle sensor 42, and a vehicle speed sensor 43 are connected to the steering ECU 46.

  These ECUs 44 to 46 each have a microcomputer composed of a CPU, a ROM, a RAM and the like as main components. The clutch ECU 44 controls the disconnection and connection of the first and second electromagnetic clutches 32 and 33 via the drive circuit 47 by executing the clutch control program of FIG. 2 (including the leveling control routine of FIG. 3). . The steering reaction force ECU 45 executes the steering reaction force control program shown in FIG. 4 and drives and controls the steering reaction force electric motor 13 via the drive circuit 48. The steering ECU 46 executes the steering control program shown in FIG. 5 to drive and control the steering electric motor 22 via the drive circuit 49.

  Next, the operation of the embodiment configured as described above will be described. When the ignition switch is turned on, the clutch ECU 44, the steering reaction force ECU 45, and the turning ECU 46 start to repeatedly execute the clutch control program, the steering reaction force control program, and the turning control program, respectively, every predetermined short time.

  The execution of the clutch control program is started in step S10 of FIG. 2, and the clutch ECU 44 is output from the steering reaction force ECU 45 and the steering ECU 46 in addition to the vehicle speed V from the vehicle speed sensor 43 in step S11. Fail flags FL1 and FL2 are input. The fail flag FL1 indicates a normal state of the steering operation device 10 by “0”, and indicates an abnormal state of the steering operation device 10 by “1”, and is initially set to “0”. The fail flag FL2 indicates a normal state of the steered device 20 by “0” and indicates an abnormal state of the steered device 20 by “1”, and is initially set to “0”. The fail flags FL1 and FL2 are output from the steering operation device 10 and the steering device 20, respectively. The steering reaction force ECU 45 and the steering ECU 46 control the steering operation device 10 and the steering device 20. As long as no abnormality is detected, it is not output, and in this state, the fail flags FL1, FL2 output to the clutch ECU 44 are treated as "0". The same applies to the steering reaction force ECU 45 and the steering ECU 46.

  Next, the clutch ECU 44 determines whether or not the fail flags FL1 and FL2 are “1” in steps S12 and S13, respectively. First, a case will be described in which both the steering operation device 10 and the steering device 20 are normal and the fail flags FL1 and FL2 are both set to “0”. Therefore, in this case, “No” is determined in steps S12 and S13, and the process proceeds to step S14. In step S14, the first and second electromagnetic clutches 32 and 33 are set to a disconnected state. Then, after execution of a leveling control routine in step S15, which will be described later, in step S17, the execution of the clutch control program is temporarily terminated.

  On the other hand, the steering reaction force ECU 45 repeatedly executes the steering reaction force control program of FIG. 4 every predetermined short time after the ignition switch is turned on. The execution of this steering reaction force control program is started in step S30, and the steering reaction force ECU 45 inputs the steering wheel steering angle θh from the steering angle sensor 41 and the vehicle speed V from the vehicle speed sensor 43 in step S31. In addition to the above, a fail flag FL2 output from the steering ECU 46 is input.

  In step S32, it is determined whether or not the fail flag FL1 is “1”. Since the steering operation device 10 is normal and the fail flag FL1 is “0”, it is determined as “No” in step S32, and the process proceeds to step S33 and subsequent steps. In step S33, an abnormality of the steering operation device 10 is checked. In step S34, it is determined whether there is an abnormality in the steering operation device 10. In checking the abnormality of the steering operation device 10, for example, disconnection, short circuit, and other abnormalities of the steering reaction force electric motor 13 are checked by inputting a signal from the drive circuit 48. In this case, as described above, since it is assumed that the steering operation device 10 is normal, the abnormality of the steering operation device 10 is not detected in the abnormality check process in step S33. Therefore, the steering reaction force ECU 45 determines “No” in step S34, that is, the steering operation device 10 is normal, and proceeds to step S35. In step S35, it is determined whether or not the fail flag FL2 is “1”. As described above, since the steering device 20 is also normal and the fail flag FL2 is set to “0”, “No” is determined in Step S35, and the process proceeds to Step S36.

  In step S36, the steering reaction force ECU 45 refers to a steering reaction force table provided in the ROM, and calculates a target steering reaction force Th * that changes according to the steering angle θh and the vehicle speed V. As shown in FIG. 6, this steering reaction force table stores a plurality of target steering reaction forces Th * that increase nonlinearly as the steering wheel steering angle θh increases for each of a plurality of representative vehicle speed values. Further, the target steering reaction force Th * takes a larger value as the vehicle speed V increases with respect to the same steering wheel steering angle θh. Instead of using the steering reaction force table, a target steering reaction force Th * that changes according to the steering angle θh and the vehicle speed V is defined in advance by a function, and the target steering is performed by using the function. The reaction force Th * may be calculated.

  Next, in step S37, the steering reaction force ECU 45 causes the drive current corresponding to the calculated target steering reaction force Th * to flow through the steering reaction force electric motor 13 in cooperation with the drive circuit 48. In S43, the execution of the steering reaction force control program is temporarily terminated. The steering reaction force electric motor 13 drives the steering input shaft 12 with a rotational torque corresponding to the target steering reaction force Th *. As a result, a target steering reaction force Th * by the steering reaction force electric motor 13 is given to the turning operation of the steering handle 11, and the driver rotates the steering handle 11 while feeling an appropriate steering reaction force. Can be operated.

  Further, after turning on the ignition switch, the steering ECU 46 repeatedly executes the steering control program of FIG. 5 every predetermined short time. Execution of this steering control program is started in step S50, and the steering ECU 46 in step S51, the steering wheel steering angle θh from the steering angle sensor 41, the actual steering angle δ from the steering angle sensor 42, In addition to inputting the vehicle speed V from the vehicle speed sensor 43, a fail flag FL1 output from the steering reaction force ECU 45 is input.

  In step S52, it is determined whether or not the fail flag FL2 is “1”. Now, since the steering device 20 is normal and the fail flag FL2 is “0”, it is determined as “No” in Step S52, and the process proceeds to Step S53 and the subsequent steps. In step S53, an abnormality of the steering device 20 is checked. In step S54, it is determined whether or not the steering device 20 is abnormal. In checking the turning device 20, for example, a disconnection, a short circuit, and other abnormalities of the turning electric motor 22 are checked by inputting a signal from the drive circuit 49. In this case, as described above, since the steering device 20 is assumed to be normal, the abnormality of the steering device 20 is not detected in the abnormality check process in step S53. Therefore, the steering ECU 46 determines “No” in step S54, that is, the steering device 20 is normal, and proceeds to step S55. In step S55, it is determined whether or not the fail flag FL1 is “1”. As described above, since each of the steering operation devices 10 is normal and the fail flag FL1 is set to “0”, “No” is determined in Step S55, and the process proceeds to Step S56.

  In step S56, the steering ECU 46 calculates the steer-by-wire target steering angle δ * using the input steering wheel steering angle θh and the vehicle speed V. In calculating the target turning angle δ *, first, referring to the first turning angle table stored in the ROM, the target turning angle δ for the standby wire that changes according to the steering wheel steering angle θh. * Calculate. As shown by a solid line in FIG. 8, the first turning angle table stores a target turning angle δ * for a standby wire that increases nonlinearly as the steering wheel steering angle θh increases. The rate of change of the steer-by-wire target steering angle δ * with respect to the steering wheel steering angle θh is small within a small range of the steering wheel steering angle θh absolute value | θh |, and the steering steering angle θh absolute value | θh | is large. It is set so as to increase. Instead of using the first turning angle table, a function indicating the relationship between the steering angle θh of the steering wheel and the target turning angle δ * for the steer-by-wire is prepared in advance, and the same function is used. Thus, the steer-by-wire target turning angle δ * may be calculated.

  Next, a vehicle speed coefficient Ka for steer-by-wire that changes according to the vehicle speed V is calculated with reference to a vehicle speed coefficient table stored in the ROM. The vehicle speed coefficient table is larger than “1” within a small range of the vehicle speed V, smaller than “1” within a large range of the vehicle speed V, and “1” as the vehicle speed V increases, as indicated by a solid line in FIG. The vehicle speed coefficient Ka for steer-by-wire that decreases non-linearly across the wheel is stored. Instead of using the vehicle speed coefficient table, a function indicating the relationship between the vehicle speed V and the steer-by-wire vehicle speed coefficient Ka is prepared in advance, and the steer-by-wire vehicle speed coefficient Ka using the same function. May be calculated.

  After the calculation of the steer-by-wire vehicle speed coefficient Ka, the calculated target turning angle δ * is multiplied by the vehicle speed coefficient Ka to correct the calculated target turning angle δ * to obtain the final target The turning angle δ * (= Ka · δ *) is calculated.

  In step S57, the difference δ * −δ between the turning angles δ * and δ is used via the drive circuit 49 so that the actual turning angle δ becomes equal to the final target turning angle δ *. The rotation of the electric motor 22 for turning is controlled. As a result, the steering electric motor 22 is rotationally driven, drives the rack bar 21 in the axial direction via the screw feed mechanism 23, and steers the left and right front wheels FW1, FW2 to the target turning angle δ *.

  By such steering control, as shown by the solid line in FIG. 8, the left and right front wheels FW1, FW2 are steered small with respect to the change in the steering angle θh in a small range of the steering angle θh, and the steering angle θh Is steered greatly with respect to the change in the steering angle θh. As a result, the left and right front wheels FW1, FW2 are steered to a large steered angle without changing the steering handle 11. 9, the left and right front wheels FW1 and FW2 are steered greatly with respect to the steering wheel steering angle θh when the vehicle speed V is low, and are steered small with respect to the steering wheel steering angle θh when the vehicle speed V increases. Is done. As a result, the turning performance of the vehicle during low-speed traveling is improved, and the traveling stability of the vehicle during high-speed traveling is improved. After the processing in step S57, the steering ECU 46 outputs the finally calculated target steering angle δ * to the clutch ECU 44 in step S58, and executes the steering control program in step S64. finish.

  Next, the leveling control routine in step S15 in FIG. 2 will be described. This leveling control routine is shown in detail in FIG. 3, and its execution is started in step S20. After the start of the execution, whether the clutch ECU 44 is immediately after the ignition switch is turned on or just after the ignition switch is turned off based on a signal from an ignition switch (not shown) in steps S21 and S22. Determine. If it is immediately after the ignition switch is turned on or just after it is turned off, “Yes” is determined in step S21 or step S22, and the process proceeds to step S27.

  In step S27, the second electromagnetic clutch 33 on the steering device 20 side is set and controlled to be connected for a predetermined time via the drive circuit 47 while the first electromagnetic clutch 32 on the steering operation device 10 side is maintained in the disconnected state. To do. Therefore, the cable 31 is connected to the conversion mechanism 26, the steering output shaft 24, and the rack bar 21 for a predetermined time during which the second electromagnetic clutch 33 is set to the connected state. In this state, when the steering handle 11 is rotated and the electric motor 22 is driven by the process of step S57 of FIG. 5, the displacement in the axial direction of the rack bar 21 is as follows: the pinion gear 25, the steering output shaft 24, It is transmitted to the cable 31 via the conversion mechanism 26 and the second electromagnetic clutch 33, and the cable 31 rotates. In this case, since the rotation of the steering output shaft 24 is accelerated by the conversion mechanism 26 and transmitted to the second electromagnetic clutch 33 and the cable 31, the cable 31 is sufficiently rotated by a slight change in the rotation angle of the steering output shaft 24. To do. The predetermined time is determined in advance to an appropriate value such that the rotation of the cable 31 is ensured.

  Further, immediately after the ignition switch is turned on or immediately after the ignition switch is turned off, particularly immediately after the ignition switch is turned off, the steering handle 11 may not be rotated. In such a case, the processing of step S27 is performed. At the same time, the electric motor 22 may be reciprocally rotated by a slight rotation angle. In addition, immediately after the ignition switch is turned off, power is supplied from the battery for a while to ensure the operation of the electric control device 40. Further, since it is not always necessary to rotate the cable 31 immediately after the ignition switch is turned on or immediately after it is turned off, the step S27 is performed in response to the ignition switch being turned on or off every time a relatively long predetermined time elapses. It is sufficient to execute the process. Alternatively, the process of step S27 may be executed every time the ignition switch is turned on or off a plurality of times.

  If it is not immediately after the ignition switch is turned on or immediately after the ignition switch is turned off, “No” is determined in both steps S21 and S22, and the process proceeds to step S23. In step S23, it is determined whether or not the input vehicle speed V is equal to or lower than a predetermined low vehicle speed V0, that is, whether or not the vehicle is stopped or traveling at a low speed. If the vehicle is stopped or traveling at a low speed, “Yes” is determined in step S23, and the process of step S27 described above is executed. Also by this, the cable 31 rotates by the drive control of the electric motor 22 by the process of step S57 of FIG. 5 as described above. In this case, since it is highly likely that the steering handle 11 is rotated and the electric motor 22 is driven and controlled, the electric motor 22 can be moved to step S27 only by setting the second electromagnetic clutch 33 to the connected state. There is no need to control the drive by processing. Also in this case, since it is not necessary to rotate the cable 31 frequently, the process of step S27 may be executed every time a relatively long predetermined time elapses.

  Further, if “No” in step S23, that is, if it is determined that the vehicle is not stopped or traveling at a low speed, the clutch ECU 44 inputs the steering wheel steering angle θh from the steering angle sensor 41 in step S24. Then, the target turning angle δ * from the turning ECU 46 is input. Next, in step S25, the clutch ECU 44 uses the input steering wheel steering angle θh to transmit the rotation of the steering input shaft 12 to the steering output shaft 24 via the cable 31 (that is, the cable 31). The turning angle δm of the left and right front wheels FW1, FW2 is calculated. In the calculation of the turning angle δm at the time of mechanical connection, the turning angle δm that changes according to the steering angle θh is calculated with reference to the second turning angle table stored in the ROM. The second turning angle table stores a turning angle δm that increases substantially linearly as the steering wheel steering angle θh increases, as indicated by a broken line in FIG. Instead of using this second turning angle table, a function indicating the relationship between the steering angle θh of the steering wheel and the turning angle δm when the machine is connected is prepared in advance, The turning angle δm at the time of connection may be calculated.

  In step S26, whether the absolute value | δ * -δm | of the difference δ * -δm between the input target turning angle δ * and the turning angle δm at the time of mechanical connection is equal to or smaller than a predetermined minute value δ0. Determine. That is, it is determined whether or not the input target turning angle δ * is substantially equal to the turning angle δm when the machine is connected. If the target turning angle δ * and the turning angle δm at the time of mechanical connection are substantially equal, “Yes” is determined in step S26, and the process of step S27 described above is executed. Also by this, the cable 31 rotates by the drive control of the electric motor 22 by the process of step S57 of FIG. 5 as described above. Also in this case, since there is a high possibility that the steering handle 11 is rotated and the electric motor 22 is driven and controlled, only the second electromagnetic clutch 33 is set to the connected state, and the electric motor 22 is moved to step S27. There is no need to control the drive by processing. Also in this case, since it is not necessary to rotate the cable 31 frequently, the process of step S27 may be executed every time a relatively long predetermined time elapses. Further, instead of the target steering angle δ *, the actual turning angle δ detected by the turning angle sensor 42 is input, and the actual turning angle δ and the turning angle δm at the time of mechanical connection are substantially equal. You may make it determine.

  Then, after the process of step S27, the clutch ECU 44 ends the execution of the leveling control routine in step S28. As described above, since the process of step S27 sets the second electromagnetic clutch 33 to the connected state for a predetermined time, the second electromagnetic clutch 33 is set to the disconnected state again after the process of step S27. Has been. Also, if “No” in step S26, that is, the target turning angle δ * and the turning angle δm at the time of mechanical connection are not substantially equal, the clutch ECU 44 ends the execution of the leveling control routine in step S28. To do.

  Next, a case where an abnormality has occurred in the steering operation device 10 will be described. In this case, the steering reaction force ECU 45 determines “Yes” in step S34 in FIG. 4, sets the fail flag FL1 to “1” in step S38, and sets “1” in step S39. The fail flag FL1 is output to the clutch ECU 44 and the steering ECU 46. In step S40, the operation of the steering reaction force electric motor 13 is stopped, and in step S43, the execution of the steering reaction force control program is temporarily ended.

  Then, once the fail flag FL1 is set to “1” in this way, the steering reaction force ECU 45 subsequently determines “Yes” in step S32, and executes the processes of steps S33 to S39 described above. Without executing the process of step S40, the execution of the steering reaction force control program is terminated in step S43. Therefore, the steering reaction force electric motor 13 does not control the application of the steering reaction force to the turning operation of the steering handle 11.

  The clutch ECU 44 inputs the fail flag FL1 set to “1” in step S11 of FIG. 2, determines “Yes” in step S12, and proceeds to step S16. In step S <b> 16, the clutch ECU 44 sets both the first and second electromagnetic clutches 32 and 33 to the connected state via the drive circuit 47. Therefore, in this state, the steering input shaft 12 is connected to the steering output shaft 24 via the conversion mechanism 15, the first electromagnetic clutch 32, the cable 31, the second electromagnetic clutch 33, and the conversion mechanism 26 so that power can be transmitted. The turning power of the steering handle 11 is transmitted to the steering output shaft 24 and is transmitted to the rack bar 21 via the pinion gear 25. Since the rack bar 21 is displaced in the axial direction to steer the left and right front wheels FW1 and FW2, the left and right front wheels FW1 and FW2 are steered by the turning operation of the steering handle 11. In this state, the reaction force accompanying the steering of the left and right front wheels FW1 and FW2 is transmitted from the steering device 20 side to the steering operation device 10 side via the cable 31, so that the driver uses this reaction force as the steering reaction force. The steering handle 11 is rotated while feeling as follows.

  On the other hand, in this state, the steering ECU 46 inputs the fail flag FL1 set to “1” in step S51 of FIG. 5, determines “Yes” in step S55, and proceeds to step S59. In step S59, the steering ECU 46 refers to an assist command value table provided in the ROM and calculates a target assist torque Ta * that changes according to the steering angle θh and the vehicle speed V. As shown in FIG. 7, this assist command value table stores a plurality of target assist torques Ta * that increase nonlinearly as the steering wheel steering angle θh increases for each of a plurality of representative vehicle speed values. The target assist torque Ta * takes a smaller value as the vehicle speed V increases with respect to the same steering wheel steering angle θh. Instead of using the assist command value table, a target assist torque Ta * that changes according to the steering angle θh and the vehicle speed V is defined in advance by a function, and the target assist torque is used by using the function. Ta * may be calculated.

  Next, in step S60, the steering ECU 46 causes the steering electric motor 22 to pass a drive current corresponding to the calculated target assist torque Ta * in cooperation with the drive circuit 49. Thereby, the steered electric motor 22 drives the rack bar 21 in the axial direction with the force corresponding to the target assist torque Ta * via the ball screw mechanism 23. As a result, in the inoperable state of the steering reaction force electric motor 13, the turning of the left and right front wheels FW 1 and FW 2 by the turning operation of the steering handle 11 is assisted by the target assist torque Ta * of the turning electric motor 22. . Therefore, the driver can easily turn the steering handle 11.

  Next, a case where an abnormality has occurred in the steering device 20 will be described. In this case, the steering ECU 46 determines “Yes” in step S54 of FIG. 5, sets the fail flag FL2 to “1” in step S61, and sets “1” in step S62. The fail flag FL1 is output to the clutch ECU 44 and the steering reaction force ECU 45. In step S63, the operation of the steering electric motor 22 is stopped, and in step S64, the execution of the steering control program is temporarily ended.

  Then, once the fail flag FL2 is set to “1” in this way, the steering ECU 46 determines “Yes” in step S52 and executes the processes of steps S53 to S62 described above. Instead, the process of step S63 is executed, and the execution of this steering control program is terminated in step S64. Therefore, the steering electric motor 22 does not control the application of the steering assist force to the steering of the left and right front wheels FW1 and FW2 and the turning operation of the steering handle 11.

  The clutch ECU 44 inputs the fail flag FL2 set to “1” in step S11 of FIG. 2, determines “Yes” in step S13, and proceeds to step S16 described above. In step S16, both the first and second electromagnetic clutches 32 and 33 are set to the connected state, and the steering input shaft 12 is connected to the conversion mechanism 15, the first electromagnetic clutch 32, the cable 31, and the second electromagnetic clutch 33. The power is transmitted to the steering output shaft 24 via the conversion mechanism 26 so that power can be transmitted. Accordingly, also in this case, the turning power of the steering handle 11 is transmitted to the steering output shaft 24 and transmitted to the rack bar 21 via the pinion gear 25. The rack bar 21 is displaced in the axial direction to steer the left and right front wheels FW1 and FW2, and the left and right front wheels FW1 and FW2 are steered by the turning operation force of the steering handle 11. Even in this state, the reaction force accompanying the steering of the left and right front wheels FW1 and FW2 is transmitted from the steering device 20 side to the steering operation device 10 via the cable 31, so the driver can use this reaction force as the steering reaction force. The steering handle 11 is rotated while feeling as follows.

On the other hand, in this state, the steering reaction force ECU 45 inputs the fail flag FL2 set to “1” in step S31 of FIG. 4, determines “Yes” in step S35, and proceeds to step S41. . In step S41, the steering reaction force ECU 45 refers to the assist command value table provided in the ROM in the same manner as the processing in step S59 of FIG. A target assist torque Ta * that changes accordingly is calculated. In this case, the target assist torque Ta * may be calculated using a function instead of using the assist command value table.

  Next, in step S42, the steering reaction force ECU 45 causes the drive current corresponding to the calculated target assist torque Ta * to flow through the steering reaction force electric motor 13 in cooperation with the drive circuit 49. Thereby, the steering reaction force electric motor 13 drives the steering input shaft 12 with the rotational force corresponding to the target assist torque Ta * via the speed reduction mechanism 14. As a result, when the steering electric motor 22 is inoperable, the steering of the left and right front wheels FW1, FW2 by the turning operation of the steering handle 11 is assisted by the target assist torque Ta * of the steering reaction force electric motor 13. . Therefore, the driver can easily turn the steering handle 11.

  As described above, in the first embodiment, if the steering operation device 10 and the steering device 20 are normal, the first and second electromagnetic clutches 32 and 33 are processed by the process of step S14 in FIG. Both are set to the disconnected state. And in this state, only the 2nd electromagnetic clutch 33 by the side of the steering apparatus 20 is sporadically connected by execution of the leveling control routine of FIG. Thereby, since the cable 31 is rotated sporadically, that is, the rotation is performed, the deterioration of the grease in the pipe in which the cable 31 is disposed can be prevented, and the phenomenon that the cable 31 is fixed in the pipe can be avoided. Then, when an abnormality occurs in the steering operation device 10 or the steering device 20, the first and second electromagnetic clutches 32 and 33 are both set to the connected state by the process of step S16 in FIG. 2, and the steering input shaft 12 and the steering output are set. Even when the shaft 24 is connected to the shaft 24 through the cable 31, the cable 31 rotates smoothly in response to the turning operation of the steering handle 11, and the left and right front wheels FW1, FW2 are always smooth. You can steer.

  Further, in the leveling control routine of FIG. 3, the rotation of the cable 31 is performed in the state immediately after the ignition switch is turned on or in the state immediately after the ignition switch is turned off by the processes of steps S21, S22, and S27. Is controlled. In this state, since the vehicle is stopped or almost stopped, even if the first electromagnetic clutch 31 is erroneously set to the connected state, the vehicle motion is not greatly affected, so the safety of the vehicle is ensured. The Further, the processing of steps S23 and S27 controls the rotation of the cable 31 while the vehicle is stopped or traveling at a low speed. Also in this case, even if the first electromagnetic clutch 31 is erroneously set to the connected state, it does not greatly affect the movement of the vehicle, so that the safety of the vehicle is ensured.

  Further, by the processing in steps S24 to S27, when the target turning angle δ * and the turning angle δm at the time of mechanical connection are substantially equal, that is, the turning of the steering handle 11 by the turning ECU 46, the turning electric motor 22 or the like. The turning angle of the left and right front wheels FW1 and FW2 according to the operation and the turning angle of the left and right front wheels FW1 and FW2 that are steered via the cable 31 according to the turning operation of the steering handle 11 (that is, in a mechanically connected state). Are substantially equal, the rotation of the cable 31 is controlled. Therefore, even if the first electromagnetic clutch 32 is erroneously set to the connected state, the steered state of the left and right front wheels FW1, FW2 changes before and after the erroneous connection of the first electromagnetic clutch 32 according to the turning operation of the steering handle 11. As a result, vehicle safety is ensured.

  In the first embodiment, when the cable 31 is rotated and rotated, the second electromagnetic clutch 33 is switched to the connected state while the first electromagnetic clutch 32 is kept disconnected. However, instead of this, the first electromagnetic clutch 32 may be switched to the connected state while the second electromagnetic clutch 33 is kept disconnected, and the cable 31 may be rotated. In this case, in step S27 of FIG. 3 of the first embodiment, only the first electromagnetic clutch 32 on the steering operation device 10 side may be switched to the connected state (see parentheses in step S27). In this case, the cable 31 is sporadically rotated via the conversion mechanism 15 by the rotation of the steering input shaft 12. As a result, also in this modified example, the same effect as that of the first embodiment is expected.

b. Second Embodiment Next, a vehicle steering apparatus according to a second embodiment of the present invention will be described. As shown in FIG. 10, the vehicle steering apparatus includes a cable rotating electric motor 51 as an actuator for rotating the cable 31.

  The cable rotating electric motor 51 is transmitted to the input shaft of the third electromagnetic clutch 52 configured similarly to the first and second electromagnetic clutches 32 and 33 of the first embodiment via a built-in speed reducer. It has become. A gear 53 is provided on the output shaft of the third electromagnetic clutch 52, and a gear 54 fixed to the fixing member 31 b of the cable 31 is engaged with the gear 53. The cable rotating electric motor 51 and the third electromagnetic clutch 52 are controlled by the clutch ECU 44 via the drive circuit 47. In this case, the clutch ECU 44 executes the leveling control routine shown in FIG. 11 as the leveling control routine of step S15 in the clutch control program of FIG. About another structure, it is the same as that of the case of the said 1st Embodiment.

  Next, the operation of the second embodiment configured as described above will be described. In this case, since the operations other than the leveling control operation of the cable 31 are the same as those in the first embodiment, only the leveling control operation will be described. The clutch ECU 44 executes the leveling control routine shown in FIG. 11 in step S15 of FIG. The execution of this leveling control routine is started in step S70. After the start of the execution, the clutch ECU 44 determines whether or not a predetermined time set in advance as a long time has elapsed after the start of the first operation of the vehicle or the processing of steps S72 to 74 described later in step S71. . If the predetermined time has not elapsed, the clutch ECU 44 determines “No” in step S71, and ends the execution of the leveling control routine in step S75.

  On the other hand, when the passage of the predetermined time is measured, the clutch ECU 44 determines “Yes” in step S71, and sets the third electromagnetic clutch 52 to the connected state in step S72. Thus, the cable rotating electric motor 51 is connected to the cable 31 via the third electromagnetic clutch 52 and the gears 53 and 54 so as to be able to transmit power. After the processing of step S72, the clutch ECU 44 operates the cable rotating electric motor 51 for a predetermined time in step S73. The electric motor 51 for rotating the cable may be rotated only in one direction or reciprocating. In this state, since the first and second electromagnetic clutches 32 and 33 are in the disconnected state as described above, the cable 31 rotates as the cable rotating electric motor 51 rotates. Then, after elapse of the predetermined time, the clutch ECU 44 sets the third electromagnetic clutch 52 to the disengaged state in step S74 and ends the execution of the leveling control routine in step S75.

  As a result, according to the second embodiment, the cable 31 is sporadically rotated by the cable rotating electric motor 51 while the first and second electromagnetic clutches 32 and 33 are in the disconnected state. The effect of preventing the deterioration of grease similar to that of the first embodiment can be expected. In this case, since the rotation of the cable 31 does not affect the operations of the steering operation device 10 and the steering device 20, the cable 31 can be freely rotated at any time during traveling of the vehicle.

  In the second embodiment, the cable rotation mechanism including the cable rotation electric motor 51, the third electromagnetic clutch 52, and the gears 53 and 54 is provided on the steering device 20 side. However, instead of this, as shown in FIG. 12, the cable rotation mechanism may be provided on the steering operation device 10 side. In this case, the gear 54 may be fixed to the fixing member 31a of the cable 31. As a result, the rotation of the cable 31 is controlled in the same manner as in the second embodiment, so that the same effect as in the second embodiment is expected.

c. Third Embodiment Next, a vehicle steering apparatus according to a third embodiment of the present invention will be described. As shown in FIG. 13, the vehicle steering apparatus divides the cable 31 of the first and second embodiments at an intermediate portion thereof to separate the first cable 31A and the second cable 31B. . The fixing member 31a of the first cable 31A is directly connected to the output shaft of the conversion mechanism 15, and the fixing member 31b of the second cable 31A is directly connected to the input shaft of the conversion mechanism 26. The first and second electromagnetic clutches 32 and 33 are interposed in series between the fixing member 31c of the first cable 31A and the fixing member 31d of the second cable 31A.

  The first and second electromagnetic clutches 32 and 33 are controlled by the clutch ECU 44 via the drive circuit 47 in the same manner as in the first and second embodiments. However, in this case, the clutch ECU 44 executes a clutch control program in which the process of the leveling control routine in step S15 is omitted from the clutch control program of FIG. Other configurations are the same as those in the first embodiment.

  In the third embodiment configured as described above, the operations other than the leveling control are the same as in the first embodiment, and the steering reaction force electric motor 13, the steered electric motor 22, and the first The second electromagnetic clutches 32 and 33 are controlled by the electric control device 40. However, in the third embodiment, since the first and second cables 31A and 31B are directly connected to the conversion mechanisms 15 and 26, respectively, the first and second electromagnetic clutches 32 and 33 are in a disconnected state. Even in the case where it is set, it rotates in conjunction with the rotation of the steering input shaft 12 and the steering output shaft 24.

  Therefore, according to the third embodiment, the first and second cables 31A and 31B always rotate. As a result, an increase in steering torque due to grease deterioration or the like is avoided, so that the steering handle 11 can be operated even when the steering handle 11 and the left and right front wheels FW1, FW2 are mechanically connected via the first and second cables 31A, 31B. The left and right front wheels FW1, FW2 can always be steered smoothly according to the turning operation.

  Furthermore, the present invention is not limited to the first to third embodiments and their modifications, and various modifications can be employed within the scope of the present invention.

  For example, in the first to third embodiments and the modifications thereof, the conversion mechanism 15 for increasing the rotation output from the steering input shaft 12 and changing the direction of the rotation axis is used, and the steering output shaft 24 is used. The conversion mechanism 26 that decelerates the rotation output to the direction and changes the direction of the rotation axis is used. However, these conversion mechanisms 15 and 24 can be omitted. That is, in the case of the first and second embodiments, the first and second electromagnetic clutches 32 and 33 may be directly connected to the steering input shaft 12 and the steering output shaft 24, respectively. In the third embodiment, the fixing members 31a and 31b of the first and second cables 31A and 31B may be directly connected to the steering input shaft 12 and the steering output shaft 24, respectively.

  In the first to third embodiments and the modifications thereof, the left and right front wheels FW1 and FW2 are steered by driving the rack bar 21 using the steerable electric motor 22. However, instead of this, the left and right front wheels FW1, FW2 are steered by assembling a steering electric motor to the steering output shaft 24 and rotationally driving the steering output shaft 24 using the electric motor. Also good.

  In the first to third embodiments and their modifications, the steering handle 11 that is rotated is adopted. However, the present invention is also applied to a vehicle steering apparatus that uses a steering handle that steers the left and right front wheels FW1 and FW2 by a linear operation such as a joystick instead of the steering handle 11.

1 is an overall schematic diagram of a vehicle steering apparatus according to a first embodiment of the present invention. It is a flowchart of the clutch control program executed by the clutch ECU of FIG. It is a flowchart which shows in detail the leveling control routine in the clutch control program of FIG. 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 steering control program performed by ECU for steering of FIG. It is a graph which shows the relationship between a steering wheel steering angle, a vehicle speed, and a target steering reaction force. It is a graph which shows the relationship between a steering wheel steering angle, a vehicle speed, and a target assist torque. It is a graph which shows the relationship between a steering wheel steering angle, a target turning angle, and the turning angle at the time of a machine connection. It is a graph which shows the relationship between a vehicle speed and a vehicle speed coefficient. It is a whole schematic diagram of the steering device of vehicles concerning a 2nd embodiment of the present invention. It is a flowchart which shows the detail of the leveling control routine performed with the clutch control program which concerns on the said 2nd Embodiment. FIG. 6 is an overall schematic diagram of a vehicle steering apparatus according to a modification of the second embodiment. It is a whole schematic diagram of the steering device of vehicles concerning a 3rd embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Steering handle, 12 ... Steering input shaft, 13 ... Electric motor for steering reaction force, 15 ... Conversion mechanism, 21 ... Rack bar, 22 ... Electric motor for steering, 24 ... Steering output shaft, 26 ... Conversion mechanism, 31 ... Cable, 32, 33 ... Electromagnetic clutch, 40 ... Electric control device, 41 ... Steering angle sensor, 42 ... Steering angle sensor, 43 ... Vehicle speed sensor, 44 ... ECU for clutch, 45 ... ECU for steering reaction force, 46 ... Steering ECU

Claims (2)

An input member connected to the steering handle and displaced in conjunction with the steering handle;
A first actuator that is connected to the input member so as to transmit power and that drives the input member to apply a reaction force to the steering operation of the steering wheel;
An output member connected to the steered wheel and displaced in conjunction with the steered wheel;
A second actuator that is steered by driving the output member connected to the output member to transmit power;
Cables connected to the input member and the output member at both ends, respectively, and rotated in conjunction with the displacement of the input member and the output member;
A first clutch interposed between the input member and one end of the cable;
A second clutch interposed between the other end of the cable and the output member;
The first and second clutches can be selectively set in a disconnected state or a connected state, and when the first and second clutches are in a disconnected state, the first and second clutches are operated according to a turning operation of a steering handle. When the actuator is driven and controlled, a steering reaction force is applied to the steering handle according to the turning operation of the steering handle, the steered wheels are steered, and the first and second clutches are in the connected state. In a vehicle steering apparatus comprising: an electric control device that allows turning of a steered wheel according to a turning operation of a steering handle by transmitting a displacement of the input member to the output member through rotation of a cable. ,
In the electric control device, when the first and second clutches are in a disengaged state, clutch control means for sporadically controlling only one of the first and second clutches in the connected state is provided. A vehicle steering apparatus.   The clutch control means includes a state immediately after the ignition switch is turned on, a state immediately after the ignition switch is turned off, a state where the vehicle is traveling at a low speed, and a turning operation of the steering handle by the second actuator. At least one of the states in which the difference between the turning angle of the steered wheel according to the steering wheel and the steered angle of the steered wheel steered via the cable according to the turning operation of the steering handle is equal to or less than a predetermined value 2. The vehicle steering apparatus according to claim 1, wherein only one of the first and second clutches is sporadically controlled to be in a connected state on condition that the state is in one state.

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