JP2008155723A - Steering device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize a steering wheel end position and freely set the steering wheel end position and the maximum turning angle of a turning wheel in a steering device for a vehicle. <P>SOLUTION: The steering device of the vehicle is equipped with a steering operation device 10 and a turning device 20. The steering operation device 10 has a motor 13 for steering reaction force for applying the reaction force to the steering operation of the steering wheel 11. The turning device 20 has a motor 22 for turning for turning right and left front wheels FW1, FW2. The steering operation device 10 and the turning device 20 are selectively and mechanically connected through a cable 31 and an electromagnetic clutch 32. When the steering angle of the steering wheel becomes not less than a predetermined value corresponding to the steering wheel end, an ECU45 for turning sets the electromagnetic clutch 32 to a connection state, and controls the motor 22 for turning in a locking state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a steer-by-wire vehicle steering device in which a steering operation device that is steered by a driver and a steering device that steers steered wheels are mechanically separated.

Conventionally, a steer-by-wire vehicle steering apparatus is well known. For example, in the following Patent Document 1, an electromagnetic clutch is interposed in a steering shaft that mechanically connects a steering operation device and a steering device, and when the electromagnetic clutch is not connected, according to the steering operation of the steering operation device, The steering motor in the steering device is electrically driven and controlled to steer the steered wheels, and the steering reaction force motor in the steering operation device is electrically driven and controlled against the driver's steering operation. There is shown a vehicle steering device that generates force and mechanically transmits a steering operation of a steering operation device to a steering device via a steering shaft when an electromagnetic clutch is engaged. In this vehicle steering device, when the vehicle is stopped, the electromagnetic clutch is set to the connected state when the steering end of the steered wheels by the steering device is mechanically disabled. By suppressing the steering operation via the steering shaft, an electric motor with a very low maximum output can be used as the steering reaction force motor. Further, in Patent Document 2 below, a flexible cable is used instead of the steering shaft, and the degree of freedom in arranging the connecting device for mechanically connecting the steering operation device and the steering device is ensured. A steer-by-wire vehicle steering device is also shown.
JP 2004-142542 A JP 2006-231957 A

  However, in the conventional method of connecting the electromagnetic clutch at the stroke end, the steered wheels are returned toward the neutral position due to the self-aligning torque of the suspension device while the vehicle is running, and the steering operation device The reaction force against the steering operation at the time fluctuates and the end position of the steering operation becomes unstable, which is not preferable. Further, the end position of the steering operation is limited to a mechanically defined position called a stroke end position by the steering device, and the degree of freedom in setting the end position and the stroke end position of the steering operation is small.

  The present invention has been made in order to cope with the above-described problems. An object of the present invention is to stabilize the end position of the steering operation and to determine the end position of the steering operation and the maximum turning angle (stroke end position) of the steered wheels. An object of the present invention is to provide a vehicle steering apparatus that can be freely set.

  In order to achieve the above object, a feature of the present invention is that a steering operation device having a steering reaction force motor that is steered by a driver and applies a reaction force to the steering operation, and a steering motor A steering device that steers the steered wheels by rotation of the steering motor, and a mechanical connection state and a non-connection state of the steering operation device and the steering device can be selectively switched. In a vehicle steering apparatus comprising a connection device, a connection control means for controlling the connection device to switch between a mechanical connection state and a non-connection state of the steering operation device and the steering device, and When the steering operation device and the steering device are mechanically disconnected, the turning of the steered wheels is controlled by controlling the rotation of the steering motor, and the steering operation device and the steering device are mechanically connected. Sometimes the rotation of the steering motor is locked In the provision and turning control means for inhibiting turning of the steered wheels.

  In this case, steering amount detection means for detecting the steering amount of the steering operation device is further provided, and the connection control means is configured to detect the steering operation device and the steering device when the detected steering amount is equal to or greater than a predetermined value. Are set in a mechanically connected state.

  In the feature of the present invention configured as described above, in a state where the connection control unit mechanically connects the steering operation device and the steering device, the steering control unit locks the rotation of the steering motor and switches the rotation. Steering wheel steering is prohibited. In this state, since the steered wheels are fixed at a predetermined steered angle, the reaction force applied from the steered device to the steering operating device via the connecting device is stable, and the end position of the steering operating device is maintained even while the vehicle is traveling. Is stable. Further, the end position by the steering operation device and the steering device can be freely set without being limited to a mechanically defined position. In particular, when the steering amount of the steering operation device is greater than or equal to a predetermined value, the connection control means sets the steering operation device and the steering device to a mechanically connected state and sets the predetermined value to an appropriate value. The end position by the steering operation device and the steering device can be freely set according to the steering amount of the steering operation device. Further, the reaction force finally applied to the steering operation device is a resultant force of the reaction force generated by the steering reaction force motor and the reaction force applied from the steering device to the steering operation device via the coupling device. The reaction force applied to the driver's steering operation can be continuously changed even when the connecting device is switched to the connected state.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall schematic diagram of the vehicle steering apparatus according to the 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. The steer-by-wire method 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 motor 13 is assembled to the lower portion of the steering input shaft 12. The steering reaction force motor 13 drives the steering input shaft 12 to rotate about the axis via the speed reduction mechanism 14.

  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, a steering motor 22 assembled in a housing (not shown) is provided. The rotation of the steering 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, and the pinion gear 25 meshes with rack teeth 21 a provided on the rack bar 21. The steering output shaft 24 rotates around the axis line in conjunction with the axial displacement of the rack bar 21.

  A flexible cable 31 as a connecting device is disposed between the steering input shaft 12 and the steering output shaft 24. The cable 31 connects the steering input shaft 12 and the steering output shaft 24 so as to rotate integrally. An electromagnetic clutch 32 is disposed between the fixing member 31 a at the upper end of the cable 31 and the lower end of the steering input shaft 12. This electromagnetic clutch 32 also constitutes a coupling device. The electromagnetic clutch 32 is set in a non-connected state when energized to disconnect the cable 31 and the steering input shaft 12 so that power cannot be transmitted, and is set in a connected state in a non-energized state so that the cable 31 and the steering input shaft 12 Are connected so that power can be transmitted. The lower end of the cable 31 is connected to the steering output shaft 24, and the steering output shaft 24 rotates integrally with the cable 31. Note that the cable 31 and the electromagnetic clutch 32 are used at the time of steering wheel end control, which will be described later, but originally, when an abnormality has occurred in the steering operation device 10, the steering device 20, or the electrical control device 40 described later, The steering input shaft 12 and the steering output shaft 24 are mechanically connected to ensure the steering of the left and right front wheels FW1 and FW2 mechanically linked to the steering operation of the steering handle 11. Since the present invention is irrelevant to the abnormality processing of the steering operation device 10, the steering device 20, or the electric control device 40, the description of the abnormality is omitted in this specification, and other than during the steering end control. The electromagnetic clutch 32 is always in a disconnected state.

  Next, the electric control device 40 that controls the steering reaction force motor 13, the steering motor 22, and the electromagnetic clutch 32 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 assembled to 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 also includes a steering reaction force electronic control unit (hereinafter referred to as a steering reaction force ECU) 44 and a steering electronic control unit (hereinafter referred to as a steering ECU) 45. A steering angle sensor 41 and a vehicle speed sensor 43 are connected to the steering reaction force ECU 44. A steering angle sensor 41, a steering angle sensor 42, and a vehicle speed sensor 43 are connected to the steering ECU 45.

  These ECUs 44 and 45 each have a microcomputer composed of a CPU, a ROM, a RAM and the like as main components. The steering reaction force ECU 44 executes the steering reaction force control program of FIG. 2, and drives and controls the steering reaction force motor 13 via the drive circuit 46. The steering ECU 45 executes the steering control program shown in FIG. 3 to control energization and deenergization of the electromagnetic clutch 32 via the drive circuit 47 and to drive and control the steering motor 22 via the drive circuit 48. .

  Next, the operation of the embodiment configured as described above will be described. By turning on an ignition switch (not shown), the steering reaction force ECU 44 and the turning ECU 45 start to repeatedly execute the steering reaction force control program and the turning control program every predetermined short time. When the ignition switch is turned on, the electromagnetic clutch 32 is controlled to be energized and set in a non-connected state, and the mechanical connection between the steering operation device 10 and the steering device 20 is released.

  The execution of the steering reaction force control program is started in step S10 of FIG. 2, and the steering reaction force ECU 44 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 S11. To do. Next, in step S12, the steering reaction force ECU 44 determines whether the steering handle 11 is in turning steering or returning steering. “Infeed steering” refers to a state in which the driver is steering the steering handle 11 from the neutral position to the left and right. During return steering means a state where the driver is steering the steering handle 11 toward the neutral position. In the specific processing of step S12, the absolute value | θhnew | of the steering wheel angle θhnew newly input by the processing of step S11 and the absolute value of steering wheel angle θhold input by the processing of the previous step S11 | θhold | is compared, and if the relationship | θhnew | ≧ | θhold | is satisfied, it is determined that the turning steering is being performed, and if the relationship | θhnew | <| θhold | is satisfied, it is determined that the return steering is being performed.

  If the steering handle 11 is being turned and steered, the steering reaction force ECU 44 determines “Yes” in step S12, and refers to the first target steering reaction force table provided in the ROM in step S13. Thus, the target steering reaction force Th * that changes according to the steering angle θh and the vehicle speed V is calculated. As shown in FIG. 4A, the first target steering reaction force table increases as the steering wheel steering angle θh increases, and the rate of change gradually decreases as the absolute value | θh | of the steering wheel steering angle θh increases. The target steering reaction force Th * is stored. The first target steering reaction force table is provided with a plurality of target steering reaction forces Th * corresponding to a plurality of different vehicle speeds V, respectively, and the target steering reaction force Th * increases as the vehicle speed V increases. The absolute value | Th * | Instead of using the first target 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 using a function, and this function is used. Thus, the target steering reaction force Th * may be calculated.

  On the other hand, if the steering handle 11 is being returned, the steering reaction force ECU 44 determines “No” in step S12, and uses the second target steering reaction force table provided in the ROM in step S14. Referring to this, the target steering reaction force Th * that changes according to the steering angle θh and the vehicle speed V is calculated. As shown in FIG. 4B, the second target steering reaction force table increases as the steering wheel steering angle θh increases, and the rate of change gradually increases as the absolute value | θh | of the steering wheel steering angle θh increases. Steering reaction force Th * is stored. The second target steering reaction force table is provided with a plurality of target steering reaction forces Th * corresponding to a plurality of different vehicle speeds V, respectively, and the target steering reaction force Th * increases as the vehicle speed V increases. The absolute value | Th * | Instead of using the second target 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 same function is used. Thus, the target steering reaction force Th * may be calculated.

  After the processes of steps S13 and S14, the steering reaction force ECU 44 outputs a drive current corresponding to the calculated target steering reaction force Th * in cooperation with the drive circuit 46 in step S15. In step S16, execution of the steering reaction force control program is temporarily terminated. The steering reaction force motor 13 drives the steering input shaft 12 with a rotational torque corresponding to the target steering reaction force Th *. As a result, the target steering reaction force Th * by the steering reaction force motor 13 is given to the turning operation of the steering handle 11, and the driver turns the steering handle 11 while feeling an appropriate steering reaction force. Can be operated. Further, since the first and second target steering reaction force tables are selectively used during the turning steering and the return steering of the steering handle 11, a hysteresis characteristic is added to the steering reaction force.

  Execution of the steering control program is started in step S20 of FIG. 3, and the steering ECU 45 controls the steering wheel steering angle θh from the steering angle sensor 41 and the actual steering angle δ from the steering angle sensor 42 in step S21. , And the vehicle speed V from the vehicle speed sensor 43 are input. Next, in step S22, it is determined whether the handle end flag HEF is “0”. In the handle end flag HEF, the absolute value | θh | of the steering angle θh of the steering wheel reaches a steering end steering angle (a predetermined value θh1 described later) corresponding to the limit steering angle (that is, the maximum steering angle) of the left and right front wheels FW1 and FW2. Therefore, it is set to “1” during the steering wheel end control described later, and is set to “0” when the left and right front wheels FW1, FW2 are steered in conjunction with the turning operation of the steering handle 11. Yes. Initially, the handle end flag HEF is set to “0”.

  First, a case where the handle end flag HEF is set to “0” will be described. In this case, the steering ECU 45 determines “Yes” in step S22, and whether the absolute value | θh | of the steering wheel steering angle θh is equal to or larger than a predetermined large positive value θh1 in step S23. Determine. The predetermined value θh1 corresponds to the limit turning angle of the left and right front wheels FW1, FW2. If the absolute value | θh | of the steering wheel steering angle θh is less than the predetermined value θh1, the steering ECU 45 determines “No” in step S23, and executes the processing from step S24. In step S24, a target turning angle δ * that changes according to the steering wheel steering angle θh is calculated with reference to the target turning angle table stored in the ROM. As shown in FIG. 5, the target turning angle table increases as the steering wheel steering angle θh increases, and the rate of change increases as the absolute value | θh | of the steering wheel steering angle θh increases. Is remembered. Instead of using the target turning angle table, a function indicating the relationship between the steering wheel steering angle θh and the target turning angle δ * is prepared in advance, and the target turning angle using the same function is prepared. δ * may be calculated.

  Next, in step S25, the steering ECU 45 refers to the vehicle speed coefficient table stored in the ROM and calculates a vehicle speed coefficient Kv that changes according to the vehicle speed V. As shown in FIG. 6, the vehicle speed coefficient table is larger than “1” in a region where the vehicle speed V is low, is smaller than “1” in a region where the vehicle speed V is high, and is non-linear across “1” as the vehicle speed V increases. The vehicle speed coefficient Kv that decreases is stored. Instead of using this vehicle speed coefficient table, a function indicating the relationship between the vehicle speed V and the vehicle speed coefficient Kv may be prepared in advance, and the vehicle speed coefficient Kv may be calculated using the function. .

After calculating the target turning angle δ * and the vehicle speed coefficient Kv, the steering ECU 45 corrects the target turning angle δ * by the vehicle speed coefficient Kv by executing the calculation of the following equation 1 in step S26. The final target turning angle δ * is calculated.
δ * = Kv · δ * Equation 1
In step S27, the difference δ * −δ between the turning angles δ * and δ is used via the drive circuit 48 so that the actual turning angle δ becomes equal to the final target turning angle δ *. Thus, the rotation of the steering motor 22 is controlled. Thereby, the steering 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 in FIG. 5, the left and right front wheels FW1, FW2 are steered small with respect to the change in the steering angle θh within a small range of the steering angle θh, and the steering angle θh is large. It is steered greatly with respect to the change of the same steering angle θh in the range. As a result, the left and right front wheels FW1, FW2 are steered to a large steered angle without changing the steering handle 11. Further, as shown in FIG. 6, the left and right front wheels FW1, 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. . After the process of step S27, the steering ECU 45 once ends the execution of the steering control program in step S35.

  Next, when the steering wheel 11 is greatly rotated and the absolute value | θh | of the steering angle θh becomes equal to or larger than the predetermined value θh1, the steering ECU 45 determines “Yes” in step S23, Steps S28 to S30 are executed. In step S28, the steering ECU 45 controls the drive circuit 48 to flow a lock current to the steering motor 22 to control the rotation of the motor 22 to the locked state. That is, the rotational position of the steered motor 22 is prohibited and remains at the current position. In this state, the turning angle of the left and right front wheels FW1, FW2 is maintained at the limit turning angle. In step S29, the steering ECU 45 controls the drive circuit 47 to release the energization of the electromagnetic clutch 32, and sets the electromagnetic clutch 32 to the connected state. In step S30, the steering ECU 45 sets the handle end flag HEF to “1”.

  In this state, the steering handle 11 is mechanically coupled to the left and right front wheels FW1, FW2 via the cable 31. Therefore, when the driver tries to further rotate the steering handle 11, in addition to the steering reaction force by the steering reaction force motor 13, the mechanical reaction force from the left and right front wheels FW 1 and FW 2 via the cable 31 is generated by the steering handle 11. To be granted. FIG. 7 shows this state. When the driver rotates the steering handle 11, the absolute value | θh | of the steering angle θh of the steering wheel increases toward the predetermined value θh1, and further exceeds the predetermined value θh1. Then, a large reaction force is applied to the steering handle 11 at the point X1 as indicated by arrows a and b in the figure. The state of the arrow a is a steering reaction force defined by the first target steering reaction force table (FIG. 4A). In the state where the absolute value | θh | of the steering wheel steering angle θh is equal to or larger than the predetermined value θh1, the target steering reaction force defined by the first target steering reaction force table is substantially constant.

  As described above, as a result of setting the handle end flag HEF to “1”, the steering ECU 45 determines “No” in Step S22 and proceeds to Step S31. In step S31, it is determined whether the absolute value | θh | of the steering wheel steering angle θh is less than a predetermined positive predetermined value θh2 that is slightly smaller than the predetermined value θh1. If the absolute value | θh | of the steering wheel steering angle θh is equal to or greater than the predetermined value θh2, the steering ECU 45 makes a “No” determination in step S31, and temporarily ends the execution of the steering control program in step S35. To do. Therefore, in this state, the steering motor 22 is kept in the locked state, and the electromagnetic clutch 32 is kept in the connected state. Therefore, in addition to the steering reaction force by the steering reaction force motor 13, the left and right front wheels FW1, FW2 Thus, the mechanical reaction force via the cable 31 is continuously applied to the steering handle 11.

  On the other hand, when the steering wheel 11 is steered back from the above state and the absolute value | θh | of the steering angle θh starts to decrease, the steering reaction force decreases as shown by the arrow c in the figure. When the absolute value | θh | of the steering wheel steering angle θh becomes less than the predetermined value θh2, the steering ECU 45 determines “Yes” in step S31 and executes the processes of steps S32 to S34. In step S32, the steering ECU 45 starts energization of the electromagnetic clutch 32 via the drive circuit 47, and sets the electromagnetic clutch 32 in a non-connected state. In step S <b> 33, the steering ECU 45 controls the drive circuit 48 to stop supplying the lock current to the steering motor 22 and releases the locked state of the motor 22. In this state, the mechanical connection between the steering operation device 10 and the steering device 20 via the cable 31 is released, and the steering handle 11 and the left and right front wheels FW1, FW2 can operate independently. In step S34, the steering ECU 45 returns the handle end flag HEF to “0”.

  After the process of step S34, the steering ECU 45 defines the left and right front wheels FW1, FW2 by the target turning angle table (FIG. 5) and the vehicle speed coefficient table (FIG. 6) by the process of steps S24 to S27 described above. Then, the vehicle is steered to a target turning angle δ * that changes according to the steering angle θh and the vehicle speed V. Then, the steering ECU 45 repeats the processing of steps S21 to S27 described above until the absolute value | θh | of the steering angle θh of the steering wheel becomes greater than or equal to a predetermined value θh1 by returning the steering wheel end flag HEF to “0”. Execute. Therefore, when the absolute value | θh | of the steering wheel steering angle θh is changed from the state equal to or larger than the predetermined value θh2 to less than the predetermined value θh2 by the return steering of the steering handle 11, the left and right front wheels FW1 and FW2 are moved to the steering handle 11 via the cable 31. Thus, only the steering reaction force by the steering reaction force motor 13 is applied to the steering handle 11. A small reaction force is applied at the point X2 as indicated by arrows c and d in FIG.

  As can be understood from the above description, according to the above-described embodiment, when the absolute value | θh | of the steering wheel steering angle θh becomes equal to or larger than the predetermined value θh1, the electromagnetic clutch 32 is processed by the processes of steps S23, S28, and S29 in FIG. Is set to the connected state, the steering input shaft 12 and the steering output shaft 24 are mechanically connected, and the steering motor 22 is set to the locked state, and the steering of the left and right front wheels FW1, FW2 is prohibited. Therefore, in this state, the steered wheels of the left and right front wheels FW1 and FW2 are fixed at the limit steered angle, and thus are given to the steering handle 11 via the rack bar 21, the steering output shaft 24, the cable 31, and the steering input shaft 12. The reaction force is stable, and the end position of the steering handle 11 is stabilized even while the vehicle is traveling. Further, since this state is defined by the absolute value | θh | of the steering wheel steering angle θh, if the predetermined value θh1 is appropriately set, the end positions of the steering wheel 11 and the left and right front wheels FW1 and FW2 are mechanically defined. It is possible to set freely without being limited to the position to be performed. Further, the reaction force finally applied to the steering handle 11 is the reaction force by the steering reaction force motor 13 and the rack bar 21, the steering output shaft 24, the cable 31 and the steering input shaft 12 from the left and right front wheels FW1 and FW2. Therefore, the steering reaction force applied to the driver's steering operation is continuously changed even when the electromagnetic clutch 32 is switched to the connected state. be able to.

  Furthermore, the present invention is not limited to the above-described embodiment, and various modifications can be employed within the scope of the present invention.

  In the above embodiment, the steering end control is performed when the absolute value | θh | of the steering angle θh is equal to or larger than the predetermined value θh1 by using the steering angle θh in the determination processing in steps S23 and S31 in FIG. The steering wheel end control is canceled when the absolute value | θh | of the steering wheel steering angle θh becomes less than a predetermined value θh2. However, since the steering wheel steering angle θh and the actual steering angle δ correspond to each other, the actual steering angle detected by the steering angle sensor 42 in place of the steering wheel steering angle θh in the determination processing of steps S23 and S31. δ may be used. That is, the handle end control is performed when the absolute value | δ | of the actual turning angle δ becomes equal to or larger than the predetermined value δ1 by the determination process in step S23, and the absolute value | δ of the actual turning angle δ by the determination process in step S31. The handle end control may be canceled when | becomes less than the predetermined value δ2. Therefore, the actual turning angle δ is equivalent to the steering angle θh with respect to the steering amount of the steering operation device 10 used for the determination processing of the steering wheel end control. The predetermined value δ1 is a value representing a large positive turning angle corresponding to the predetermined value θh1, and the predetermined value δ2 represents a large positive turning angle slightly smaller than the predetermined value δ1 corresponding to the predetermined value θh2. Value.

  In the above embodiment, the flexible cable 31 is used as a connecting device that connects the steering input shaft 12 and the steering output shaft 24. However, if the degree of freedom in spatial arrangement of the cable 31 is not a problem, a shaft may be used instead of the cable 31.

  In the embodiment described above, 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 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 steering control program performed by ECU for steering of FIG. It is a graph which shows the relationship between the steering angle and the target steering reaction force during the steering steering of the steering wheel. It is a graph which shows the relationship between a steering wheel steering angle and the target steering reaction force during the steering return steering. It is a graph which shows the relationship between a steering wheel steering angle and a target turning angle. It is a graph which shows the relationship between a vehicle speed and a vehicle speed coefficient. It is a graph which shows the relationship between a steering wheel steering angle and steering reaction force in a steering wheel end control state.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Steering handle, 12 ... Steering input shaft, 13 ... Steering reaction force motor, 21 ... Rack bar, 22 ... Steering motor, 24 ... Steering output shaft, 31 ... Cable, 32 ... Electromagnetic clutch, 41 ... Steering angle Sensor: 42 ... Steering angle sensor, 43 ... Vehicle speed sensor, 44 ... Steering reaction force ECU, 45 ... Steering ECU

Claims (2)

A steering operation device having a steering reaction force motor that is steered by the driver and applies a reaction force to the steering operation;
A steering device that has a steering motor and steers the steered wheels by rotation of the steering motor;
In a vehicle steering apparatus comprising a coupling device capable of selectively switching between a mechanically connected state and a non-connected state of the steering operation device and the steering device,
Connection control means for controlling the connection device to control switching between a mechanical connection state and a non-connection state of the steering operation device and the steering device;
When the steering operation device and the steering device are not mechanically connected, the steering wheel is controlled by controlling the rotation of the steering motor, and the steering operation device and the steering device are mechanically connected. A vehicle steering apparatus comprising: a steering control unit that locks the rotation of the steering motor and prohibits the turning of the steered wheels in a state. In the vehicle steering apparatus according to claim 1,
Further provided is a steering amount detection means for detecting a steering amount of the steering operation device,
The connection control means is a vehicle steering device that sets the steering operation device and the steering device to a mechanically connected state when the detected steering amount is equal to or greater than a predetermined value.

Images