JP5293088B2 - Vehicle steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain required steering reaction force by properly driving a steering reaction force motor 13 without increase cost so much. <P>SOLUTION: A boosting circuit 50 is provided at an input portion of a steering motor driving circuit 38, thereby passing a large electric current through a steering motor 24. A capacitor 70 charged by the output of the boosting circuit 50 is provided in parallel with the steering motor driving circuit 38. When fast steering operation is detected, a changeover switch 60 is switched to connect the capacitor 70 to a steering reaction force motor driving circuit 37. Therefore, electrical charge accumulated in the capacitor 70 can be used as a driving power source of a steering reaction force motor 13. Consequently, even if the fast steering operation is carried out, suitable steering reaction torque can be given, and it is not necessary to provide the boosting circuit in a preceding stage of the steering reaction force motor driving circuit 37. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a steering-by-wire steering apparatus in which a steering wheel operating unit and a steering unit that steers a wheel are mechanically separated.

  Conventionally, this type of vehicle steering apparatus has a steering handle that is operated by a driver, a reaction force applying apparatus that applies a steering reaction torque to the operation of the steering handle, and a wheel that rotates according to the operation of the steering handle. And a steered wheel drive device that steers the steered wheels.

  The reaction force imparting device has a spring reaction force torque component that provides a force to return the steering handle to the neutral position and a friction reaction force torque component that simulates the frictional resistance of the steering mechanism in order to give an appropriate response to the steering operation. The target reaction force torque is calculated by adding a plurality of reaction force torque components such as a viscous reaction force torque component that simulates the viscous resistance generated by the steering handle turning operation, and the steering reaction force motor is The target steering reaction torque is applied to the steering wheel by driving control.

  The steered wheel drive device calculates a target turning angle based on the steering angle detected by the steering angle sensor, and steers the steering angle so that the turning angle detected by the steering angle sensor becomes the target turning angle. The motor is driven to steer the steered wheels.

For example, in the steering-by-wire type steering device proposed in Patent Document 1, in order to increase the neutral rigidity in the vicinity of the neutral position of the steering handle, it is connected to the steering shaft via a clutch separately from the steering reaction force motor. Equipped with a regenerative motor. In the steering angle range in the vicinity of the neutral position, the steering reaction motor is stopped and the regenerative motor is rotated by reverse input from the steering shaft by connecting the clutch to operate as a generator. Is adopted to regenerate the vehicle battery.
JP 2003-237612 A

  In such a steering-by-wire type steering device, when a fast steering operation is performed, both the steering motor and the steering reaction force motor require large electric power. However, when the power supplied from the in-vehicle power supply is insufficient, the steering cannot follow, and the steering reaction force is insufficient to restrict the fast steering operation. For this reason, a deviation occurs between the steering operation and the wheel turning, which gives the driver a feeling of strangeness.

  In the apparatus proposed in Patent Document 1 described above, a regenerative motor is provided in addition to the steering reaction force motor, but this regenerative motor increases the rigidity in the vicinity of the neutral position of the steering handle, It does not supplement the reaction torque generated by the steering reaction force motor during operation. Therefore, the above-mentioned problem remains when a fast steering operation is performed.

  When the electric motor is driven with high power, a booster circuit may be provided in the power supply path from the in-vehicle power supply to the motor drive circuit. For a steering motor, it is a good idea to provide a booster circuit in front of the motor drive circuit to consume a large amount of power even during normal steering operation. However, for a steering reaction force motor, fast steering operation is performed. It requires a large amount of power only when it is broken, and usually does not require a large amount of power. Therefore, it is not preferable from the viewpoint of cost to provide a booster circuit before the steering reaction motor driving circuit.

  The present invention has been made to cope with the above-described problem, and an object thereof is to appropriately drive a steering reaction force motor to obtain a desired steering reaction force without incurring a significant cost increase. And

In order to achieve the above object, the present invention is characterized in that a steered motor for steered steered wheels, a steered motor drive circuit for driving the steered motor, and the steered from an in-vehicle power source. A booster circuit provided in a power supply path to the motor drive circuit for the vehicle and boosting the output voltage of the in-vehicle power supply to supply power to the steered motor drive circuit; and for the steering according to a steering operation of the steering wheel Steering control means for controlling energization to the steering motor by controlling a motor drive circuit, a steering reaction force motor for applying a steering reaction force torque to the steering operation of the steering handle, and the vehicle-mounted A steering reaction force motor drive circuit that drives the steering reaction force motor by being supplied with power from a power source without going through a booster circuit, and controls the steering reaction force motor drive circuit according to a steering operation of the steering handle. The steering reaction force motor A steering reaction force control means for controlling the energization of, connected from the booster circuit in parallel to the power supply path to the steering motor drive circuit, is charged by the output of said boosting circuit, the steering motor drive circuit A capacitor that is not allowed to discharge , a chargeable mode in which the capacitor is connected to the booster circuit to allow charging, and the capacitor is connected to the steering reaction force motor drive circuit to drive the steering reaction force motor. A charge / discharge switching circuit for switching a dischargeable mode that enables discharge to the circuit, a steering speed detecting means for detecting a steering speed of the steering wheel, and a steering speed detected by the steering speed detecting means exceeds a set speed And charge / discharge switching circuit control means for controlling the charge / discharge switching circuit to switch from the chargeable mode to the dischargeable mode. That.

  In the present invention, a booster circuit is provided in the power supply path between the in-vehicle power source and the steered motor drive circuit, and the booster circuit boosts the output voltage of the in-vehicle power source to supply power to the steered motor drive circuit. Is done. Accordingly, the steered motor drive circuit is supplied with a boosted power supply, and therefore, the steered wheels can be steered satisfactorily by supplying a large current to the steered motor. A capacitor is connected in parallel to the steered motor drive circuit in a power supply path (a boosted power supply path) from the booster circuit to the steered motor drive circuit. Therefore, the capacitor is charged by the output of the booster circuit. On the other hand, the steering reaction force motor drive circuit is supplied with power from a vehicle-mounted power supply without going through a booster circuit.

  The charge / discharge switching circuit is configured to switch between a chargeable mode and a dischargeable mode. In the chargeable mode, the capacitor and the output unit of the booster circuit are connected. Therefore, the capacitor is well charged by the output of the booster circuit. In the dischargeable mode, the capacitor and the power input unit of the steering reaction force motor drive circuit are connected. Therefore, the steering reaction force motor drive circuit is supplied with power from both the in-vehicle power supply and the capacitor.

As a result, according to the present invention, the capacitor is charged by the output of the booster circuit and a large amount of power is required for the steering reaction force motor in a normal time when a large amount of power is not required for driving the steering reaction force motor. Then, the charge / discharge switching circuit can be switched from the chargeable mode to the dischargeable mode, and the charge stored in the capacitor can be supplied to the steering reaction force motor drive circuit. As a result, it is possible to suppress a shortage of energization amount to the steering reaction force motor without providing a booster circuit upstream of the steering reaction force motor drive circuit. Therefore, an appropriate steering reaction force can be obtained without causing a significant cost increase.
In the present invention, the steering speed detecting means detects the steering speed of the steering wheel, and when the detected steering speed exceeds the set speed, the charge / discharge switching circuit control means controls the charge / discharge switching circuit. Switch from chargeable mode to dischargeable mode. The steering reaction force to be applied to the steering wheel is desirably increased as the steering speed increases. Therefore, in the present invention, if the steering speed is smaller than the set speed, the charging / discharging switching circuit is set when the steering speed exceeds the set speed by setting the chargeable mode, charging the capacitor and waiting. Control to dischargeable mode. Therefore, when a fast steering operation is performed, the electric charge stored in the capacitor can be used as a drive power source for the steering reaction force motor. For this reason, even when a fast steering operation is performed, an appropriate steering reaction torque can be applied, and the occurrence of a deviation between the steering operation and the wheel turning can be suppressed.

  The charge / discharge switching circuit is connected to, for example, a charging path connected to the power supply path from the booster circuit to the steering motor drive circuit and a power supply path from the on-vehicle power supply to the steering reaction force motor drive circuit. And a changeover switch that selectively switches the connection destination of the capacitor between the charging path and the discharging path.

  Another feature of the present invention is provided with switchback detection means for detecting switchback of the steering wheel or switchback of the steered wheel, and the charge / discharge switching circuit control means is configured to detect the switchback by the switchback detection means. When turning back of the steering wheel or turning back of the steered wheel is detected, the chargeable mode is maintained regardless of the steering speed detected by the steering speed detecting means.

  Assuming that quick turning operation and turning operation of the steering wheel are repeated, a large-capacity capacitor is required. Therefore, in the present invention, when there is a possibility that the steering motor rotates by the self-aligning torque to generate electric power, the power generated by the steering motor is regenerated and charged in the capacitor.

  When the steered wheels are switched back, the generated power is often obtained from the steered motor by the self-aligning torque. Therefore, the switchback detection means detects the switchback of the steering wheel or the switchback of the steered wheels. The charge / discharge switching circuit control means maintains the chargeable mode regardless of the steering speed when the steering wheel switchback or the steered wheel switchback is detected. Therefore, the capacitor and the steering motor drive circuit are connected, and the power generated by the steering motor can be regenerated and charged in the capacitor. As a result, it is not necessary to increase the capacity of the capacitor, and it can be carried out at a low cost.

  Another feature of the present invention is that a regenerative switching circuit that switches between a regenerative enabling mode in which power generated by the steering motor can be regenerated to the in-vehicle power source and a regenerative impossible mode that cannot be regenerated, and a vehicle speed detection that detects the vehicle speed. And regenerative switching circuit control means for controlling the regenerative switching circuit to switch from the non-regenerative mode to the regenerative mode when the vehicle speed detected by the vehicle speed detecting means becomes less than a set vehicle speed. There is.

  In the present invention, a regenerative switching circuit, a vehicle speed detecting means, and a regenerative switching circuit control means are provided, and when the vehicle speed becomes less than the set vehicle speed, the regenerative switching circuit control means controls the regenerative switching circuit to start from the non-regenerative mode Switch to regenerative mode. That is, when the vehicle speed is less than the set vehicle speed, the regenerative mode is set, and when the vehicle speed exceeds the set vehicle speed, the regenerative disable mode is set. In the regenerative mode, the power generated by the turning motor rotating by reverse input from the road surface can be regenerated to the in-vehicle power source. This power regeneration can be executed safely because it is performed when the vehicle speed detected by the vehicle speed detection means is less than the set vehicle speed.

  Another feature of the present invention is provided with switchback detection means for detecting switchback of the steering wheel or switchback of the steered wheels, and the regeneration switching circuit control means is configured to detect the vehicle speed detected by the vehicle speed detection means. When the vehicle speed is lower than the set vehicle speed, and the switchback detecting means detects the switchback of the steering wheel or the switchback of the steered wheels, the regeneration switching circuit is controlled to perform the regeneration. The mode is switched from the mode to the regenerative mode.

  In the present invention, when the vehicle speed is lower than the set vehicle speed and the steered wheels are easily switched back by the self-aligning torque and the generated power can be easily obtained from the steered motor (also when the steering wheel is switched back), the regeneration is performed. Since the mode is set to the possible mode, the period of the regenerative mode can be made more appropriate.

  Another feature of the present invention is that the regeneration switching circuit includes a regeneration path connected to a power input unit of the steering motor drive circuit, and in the regenerative mode, the connection between the in-vehicle power supply and the booster circuit. And disconnecting the in-vehicle power source and the regenerative path, and disconnecting the in-vehicle power source and the regenerative path in the non-regenerative mode and connecting the in-vehicle power source and the booster circuit. .

  Since the electric power generated by the steering motor cannot be regenerated to the in-vehicle power source via the booster circuit, in the regenerative mode, the in-vehicle power source and the power input part of the steered motor drive circuit are connected through the regeneration path. Connecting. Therefore, the electric power generated by the steering motor can be regenerated to the in-vehicle power supply via the regenerative path. In this regenerative mode, power can be supplied from the in-vehicle power supply even when power supply is required by the steering motor. Further, in the regeneration disabled mode, the output voltage of the in-vehicle power supply is boosted and the power is supplied to the steering motor drive circuit, so that the steering motor can be driven appropriately even at the time of cutting.

  Hereinafter, a vehicle steering apparatus according to an embodiment of the present invention will be described with reference to the drawings. First, the vehicle steering apparatus according to the first embodiment will be described. FIG. 1 shows a schematic system configuration of a vehicle steering apparatus according to the first embodiment, and FIG. 2 shows a power supply system thereof.

  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 adopted. 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 for generating a steering reaction force incorporating a deceleration mechanism is assembled to the lower end of the steering input shaft 12. As the steering reaction force motor 13, for example, a three-phase brushless motor is used.

  The steered device 20 includes a steered shaft 21 that extends in the left-right direction of the vehicle. The left and right front wheels FW1, FW2 are connected to both ends of the steered shaft 21 via tie rods 22a, 22b and knuckle arms 23a, 23b so as to be steerable. The left and right front wheels FW1 and FW2 are steered left and right by the displacement of the steered shaft 21 in the axial direction. On the outer periphery of the steered shaft 21, a steered motor 24 assembled in a housing (not shown) is provided. The rotation of the steering motor 24 is decelerated by the screw feed mechanism 26 and is converted into a displacement in the axial direction of the steered shaft 21. Similarly to the steering reaction force motor 13, for example, a three-phase brushless motor is used for the steering motor 24.

  Next, the electric control device 30 that controls the rotation of the steering reaction force motor 13 and the steering motor 24 will be described. The electric control device 30 includes a steering angle sensor 31 and a turning angle sensor 32. The steering angle sensor 31 is assembled to the steering input shaft 12, detects a rotation angle from the reference point of the steering handle 11, and outputs a signal representing the steering angle θ. Hereinafter, the steering angle θ detected by the steering angle sensor 31 is referred to as an actual steering angle θ. With respect to the actual steering angle θ, the reference point is the neutral position “0”, the left angle is represented by a positive value, and the right angle is represented by a negative value.

  The turning angle sensor 32 detects the amount of axial displacement from the reference point of the turning shaft 21 and outputs a signal representing the turning angle δ of the left and right front wheels FW1, FW2. As the turning angle sensor 32, a rotation angle sensor that detects a rotation angle of the turning motor 24 with respect to the reference position of the rotor is used. The rotation angle of the rotor of the turning motor 24 takes a value corresponding to the amount of movement of the turning shaft 21 in the axial direction, that is, the amount of change in the turning angle. Therefore, the turning angle sensor 32 detects the turning angle δ from the rotation angle with respect to the reference position of the turning motor 24. Hereinafter, the turning angle δ detected by the turning angle sensor 32 is referred to as an actual turning angle δ. The actual turning angle δ represents the displacement of the turning shaft 21 corresponding to leftward turning of the left and right front wheels FW1 and FW2 as a positive value with the reference point being the neutral position “0”, and the right and left front wheels FW1 and FW2 The displacement of the turning shaft 21 corresponding to the turning in the right direction is represented by a negative value.

  In addition, the electric control device 30 includes a steering reaction force electronic control unit (hereinafter referred to as a steering reaction force ECU) 35 and a steering electronic control unit (hereinafter referred to as a steering ECU) that are communicably connected to each other. 36. A steering angle sensor 31 is connected to the steering reaction force ECU 35. A steering angle sensor 31 and a turning angle sensor 32 are connected to the steering ECU 36.

  The steering reaction force ECU 35 and the steering ECU 36 each have a microcomputer including a CPU, a ROM, a RAM, and the like as main components. As shown in FIG. 2, the steering reaction force ECU 35 controls a steering reaction force control unit 35 a that drives and controls the steering reaction force motor 13 via a steering reaction force motor drive circuit 37, and controls a changeover switch 60 described later. The charging / discharging control part 35b which controls charging / discharging of the capacitor 70 is provided. The steering ECU 36 drives and controls the steering motor 24 via the steering motor drive circuit 38.

  The steering reaction force motor drive circuit 37 and the steering motor drive circuit 38 are each constituted by a three-phase inverter circuit, and an internal arm circuit is generated by a PWM control signal output from the steering reaction force ECU 35 and the steering ECU 36. The duty ratios of a plurality of switching elements (for example, MOS-FETs) constituting the motor are controlled, and the steering reaction force motor 13 and the steering motor 24 are energized with an energization amount corresponding to the duty ratio. The steering reaction force motor drive circuit 37 is provided with a current sensor 33 for detecting a drive current flowing in each phase of the steering reaction force motor 13, and the steering motor drive circuit 38 has a steering motor. A current sensor 34 for detecting a drive current flowing in each of the 24 phases is provided. The drive current value signals detected by the current sensors 33 and 34 are supplied to the steering reaction force ECU 35 and the steering ECU 36, respectively.

  Next, a power supply system for driving the steering reaction force motor 13 and the steering motor 24 will be described with reference to FIG. The vehicle steering apparatus is supplied with power from the in-vehicle battery 100. The in-vehicle battery 100 is a general 12V storage battery and is charged by an alternator (not shown). The in-vehicle battery 100 supplies power not only to the steering device but also to other in-vehicle electric loads, and corresponds to the in-vehicle power source of the present invention.

  A main power supply line 110 is connected to the plus terminal of the in-vehicle battery 100. The main power supply line 110 branches into a steering reaction power supply line 111 and a steering power supply line 112 on the way. The steering reaction force power supply line 111 is connected to the power input portion of the steering reaction force motor drive circuit 37. In the steering reaction force motor drive circuit 37, the motor drive line 113 is drawn from between the upper arm and the lower arm constituting the three-phase inverter circuit. The motor drive line 113 is connected to the power input terminal of the steering reaction force motor 13.

  The turning power supply line 112 is connected to the input of the booster circuit 50. The booster circuit 50 is configured by a general-purpose DC-DC converter, and boosts the input power supply voltage to, for example, 42V. One end of the boosted power supply line 114 is connected to the output section of the booster circuit 50. The other end of the boosted power supply line 114 is connected to the power input unit of the steering motor drive circuit 38. In the steered motor drive circuit 38, a motor drive line 124 is drawn from between the upper arm and the lower arm constituting the three-phase inverter circuit. The motor drive line 124 is connected to a power input terminal of the steering motor 24.

  The boosted power supply line 114 is provided with a charging line 115 branched in the middle thereof. The steering reaction force power supply line 111 is provided with a discharge line 116 branched in the middle thereof. The other end of the charging line 115 is connected to the selection port A of the changeover switch 60, and the other end of the discharge line 116 is connected to the selection port B of the changeover switch 60. The changeover switch 60 is configured to switch between the common port O and the selection port B, and the common port O and the selection port B based on a control signal output from the charge / discharge control unit 35b of the steering reaction force ECU. The state is switched between two states, that is, an electrically connected state. The changeover switch 60 may be constituted by a semiconductor element or a mechanical electromagnetic relay as long as it can be switched between two positions by an electric signal.

  A capacitor 70 is connected to the common port O of the changeover switch 60. The capacitor 70 is a power storage device that can be rapidly charged and discharged, called an electric double layer capacitor, and is provided between the common port O and the ground.

  The charging line 115 is provided with a diode 117. The diode 117 is provided with the cathode directed toward the changeover switch 60 and the anode directed toward the boosted power supply line 114. Therefore, the charging line 115 is allowed to be energized only in the direction from the boosted power supply line 114 toward the changeover switch 60. The discharge line 116 is also provided with a diode 118. The diode 118 is provided with the cathode directed toward the steering reaction force power supply line 111 and the anode directed toward the changeover switch 60. Therefore, the discharge line 116 is allowed to be energized only in the direction from the changeover switch 60 toward the steering reaction force power supply line 111. Further, the steering reaction force power supply line 111 is provided with a diode 119 closer to the main power supply line 110 than the connection point with the discharge line 116. The diode 119 is provided with the cathode directed toward the steering reaction force motor drive circuit 37 and the anode directed toward the main power supply line 110. Therefore, the current flowing through the discharge line 116 does not go to the main power supply line 110 but flows to the steering reaction force motor drive circuit 37 side.

  In the power supply system configured as described above, power is supplied from the in-vehicle battery 100 to the steering reaction force motor drive circuit 37 and the steering motor drive circuit 38. In this case, since the booster circuit 50 is provided in the middle of the power supply path to the steered motor drive circuit 38, the power supply voltage supplied to the steered motor drive circuit 38 is high. Therefore, the steered motor drive circuit 38 can flow a large current to the steered motor 24, and can generate a large steered torque for steering the left and right front wheels FW1, FW2.

  In a state where the common port O and the selection port A of the changeover switch 60 are connected, the charging line 115 and the capacitor 70 are connected. Therefore, the capacitor 70 is connected to the booster circuit 50 in parallel with the steered motor drive circuit 38 and is charged by the output of the booster circuit 70. In this case, since the boosted power supply is used, the capacitor 70 can be charged well. Capacitor 70 is charged until the voltage is approximately equal to the output voltage of booster circuit 50. Hereinafter, a state in which the common port O and the selected port A are connected is referred to as a chargeable mode. In the chargeable mode, when the steering motor 24 rotates and generates power by reverse input from the road surface, the generated power is regenerated in the capacitor 70.

  In a state where the changeover switch 60 is switched and the common port O and the selection port B are connected, the connection between the capacitor 70 and the charging line 115 is cut off, and the capacitor 70 and the discharging line 116 are connected. Therefore, the capacitor 70 is connected to the steering reaction force motor drive circuit 37 as an auxiliary power source using the stored charge as a power source. As a result, the steering reaction force motor drive circuit 37 is in a state of being provided with two power sources, the in-vehicle battery 100 and the capacitor 70. Hereinafter, a state in which the common port O and the selected port B are connected is referred to as a dischargeable mode.

  Since the output voltage of the capacitor 70 at the time of full charge is approximately the same as the output voltage of the booster circuit 50, the in-vehicle battery 100 with respect to the steering reaction force motor drive circuit 37 when switched to the dischargeable mode. Supply a higher voltage power. Therefore, a large current can flow from the capacitor 70 to the steering reaction force motor 13, and a large steering reaction force torque can be generated. Further, since the electric charge discharged from the capacitor 70 is not returned to the in-vehicle battery 100 by the action of the diode 119, it can be used effectively for driving the steering reaction force motor 13.

  In this embodiment, the changeover switch 60, the charge line 115, and the discharge line 116 correspond to the charge / discharge switching circuit of the present invention.

  Next, turning angle control performed by the turning ECU 36 will be described. FIG. 3 is a flowchart showing a turning angle control routine. The turning angle control routine is stored as a control program in the ROM of the steering ECU 36, is started by turning on an ignition switch (not shown), and is repeated at a predetermined short cycle.

  When this control routine is activated, the steering ECU 36 reads the actual steering angle θ and the actual steering angle δ detected by the steering angle sensor 31 and the steering angle sensor 32 in step S11. Subsequently, in step S12, a target turning angle δ * corresponding to the actual steering angle θ is calculated with reference to a target turning angle table stored in advance in the ROM. This target turning angle table sets the correspondence between the steering angle θ of the steering handle 11 and the target turning angle δ *, and as shown in FIG. 4, the target turning increases as the steering angle θ increases. The angle δ * is stored.

  In this step S12, the actual steering angle θ is substituted into the steering angle θ of the target turning angle table, and the target turning angle δ * corresponding to the actual steering angle θ is obtained. Instead of using the target turning angle table, a function in which the correspondence relationship between the steering angle θ and the target turning angle δ * is predetermined is stored in the ROM, and the actual steering is performed using the function. The target turning angle δ * corresponding to the angle θ may be calculated.

  Subsequently, in step S13, the steering ECU 36 calculates a target drive current value that is proportional to a difference value (δ * −δ) obtained by subtracting the actual turning angle δ from the target turning angle δ *. By outputting a control signal (for example, a PWM control signal) corresponding to the value to the steering motor drive circuit 38, the target drive current is caused to flow to the steering motor 24. This energization control is performed, for example, by feeding back the drive current detected by the current sensor 34. Thereby, the steering motor 24 is driven and controlled so that the difference value (δ * −δ) becomes “0”, and the turning shaft 21 is driven in the axial direction through the screw feed mechanism 26 by the rotation. To do. The left and right front wheels FW1 and FW2 are steered to the target turning angle δ * by the displacement of the turning shaft 21 in the axial direction. As a result, the left and right front wheels FW1, FW2 are steered according to the turning operation of the steering handle 11, and the vehicle is turned left and right. Thus, the steered ECU 36 once ends the steered angle control routine when the process of step S13 is executed. Then, the turning angle control routine is repeated at a predetermined short cycle. The steering ECU 36 that executes this steering control routine corresponds to the steering control means of the present invention.

  Next, the steering reaction force control performed by the steering reaction force control unit 35a of the steering reaction force ECU 35 will be described. FIG. 5 is a flowchart showing a steering reaction force control routine. The steering reaction force control routine is stored as a control program in the ROM of the steering reaction force ECU 35, is started by turning on an ignition switch (not shown), and is repeated at a predetermined short cycle.

  When this control routine is activated, the steering reaction force control unit 35a first reads the actual steering angle θ detected by the steering angle sensor 31 in step S21. Next, in step S22, a spring reaction force torque component Ta is calculated. This spring reaction force torque component Ta is a torque component that attempts to return the steering handle 11 to the neutral position among the steering reaction force torque applied to the steering handle 11, and is calculated with reference to the spring reaction force torque table. As shown in FIG. 6, the spring reaction force torque table stores the correspondence between the steering angle θ of the steering handle 11 and the spring reaction force torque component Ta in the ROM of the steering reaction force ECU 35. As can be seen from this table, the spring reaction force torque component Ta is set to increase as the steering angle θ increases.

  Subsequently, the steering reaction force control unit 35a calculates a friction reaction force torque component Tb in step S23. The friction reaction force torque component Tb is a torque component that simulates the frictional resistance of the steering mechanism among the steering reaction force torque applied to the steering handle 11. The friction reaction force torque component Tb depends on the steering speed ω (= dθ / dt) obtained by differentiating the steering angle θ with time and is calculated with a hysteresis characteristic. It is calculated using the friction reaction force torque table shown in FIG. 7 in which the correspondence relationship with the torque component Tb is stored. This friction reaction force torque table is stored in the ROM of the steering reaction force ECU 35.

  The steering speed ω is obtained by calculating the amount of change per unit time of the actual steering angle θ detected by the steering angle sensor 31 because this control routine is repeatedly executed at a predetermined short period. In step S23, the calculated actual steering speed ω is substituted for the steering reaction speed ω of the friction reaction force torque table, and a target friction reaction force torque component Tb corresponding to the actual steering speed ω is obtained.

  Subsequently, the steering reaction force control unit 35a calculates a viscous reaction force torque component Tc in step S24. The viscous reaction force torque component Tc is a torque component that simulates the viscous resistance generated in accordance with the turning operation of the steering handle 11 out of the steering reaction force torque applied to the steering handle 11. Since the viscous reaction force torque component Tc is calculated in proportion to the steering acceleration dω / dt obtained by differentiating the steering speed ω with time, the correspondence relationship between the steering acceleration dω / dt and the viscous reaction force torque component Tc is stored. The viscosity reaction force torque table shown in FIG. This viscous reaction force torque table is also stored in the ROM of the steering reaction force ECU 35. In step S24, the actual steering acceleration dω / dt obtained by calculating the amount of change per unit time of the actual steering speed ω is substituted into the steering acceleration dω / dt of the viscous reaction force torque table, and the actual steering acceleration dω / A target viscous reaction force torque component Tc corresponding to dt is obtained.

  In calculating each reaction force torque component Ta, tb, tc, it is not always necessary to use a table, and a function for deriving the reaction force torque component from each parameter such as the actual steering angle θ is stored in the ROM. You may make it calculate using the function.

  Next, the steering reaction force control unit 35a calculates a target steering reaction force torque T * in step S25. The target steering reaction torque T * is obtained by adding the spring reaction force torque component Ta, the friction reaction force torque component Tb, and the viscous reaction force torque component Tc calculated in steps S22 to S24. In the present embodiment, the target steering reaction torque T * is calculated from these three torque components Ta, Tb, Tc. However, other torque components may be taken into account. You may reduce the kind of component. Further, the target steering reaction torque T * may be changed according to the vehicle speed.

  When the target steering reaction torque T * is thus calculated, the steering reaction force control unit 35a uses a control signal (for example, a PWM control signal) corresponding to the target steering reaction torque T * for the steering reaction force in step S26. By outputting to the motor drive circuit 37, a drive current corresponding to the target steering reaction torque T * is caused to flow to the steering reaction force motor 13. This energization control is performed, for example, by feeding back the drive current detected by the current sensor 33. And this steering reaction force control routine is once complete | finished.

  Since this steering reaction force control routine is repeated at a predetermined short cycle, a steering reaction force equal to the sequentially calculated target steering reaction force torque T * is applied to the steering handle 11 via the steering input shaft 12. Thereby, an appropriate reaction torque is applied to the turning operation of the steering handle 11 by the driver, and the driver can comfortably rotate the steering handle 11 while feeling the steering reaction force. The steering reaction force control unit 35a that executes the steering reaction force control routine corresponds to the steering reaction force control means of the present invention.

  Thus, even if the steering operation device 10 and the steering device 20 are mechanically separated by executing the steering angle control routine and the steering reaction force control routine in parallel, the driver The left and right front wheels FW1, FW2 are steered in the direction according to the steering operation, and the reaction force according to the steering operation can be felt. When the left and right front wheels FW1, FW2 are steered to the target steered angle δ * by executing such a steered angle control routine, it is necessary to flow a large current to the steered motor 24, particularly during a stationary operation. Therefore, in the present embodiment, a configuration is adopted in which a booster circuit 50 is provided in front of the steered motor drive circuit 38 to boost the in-vehicle power supply voltage and supply the boosted power to the steered motor drive circuit 38. doing. For this reason, a large current can be supplied to the steering motor 24, and a desired steering torque can be obtained.

  On the other hand, the steering reaction force motor 13 does not normally need to be driven with a large current, but the energization amount is insufficient and a predetermined steering reaction force cannot be obtained only when a fast steering operation is performed. There is. In this case, the steering wheel 11 turns before the steering of the left and right front wheels FW1 and FW2, causing the driver to feel uncomfortable. If a new booster circuit is provided in the steering reaction force power supply line 111, a large current can be supplied to the steering reaction force motor 13, and this problem can be solved, but the cost is greatly increased. Therefore, in the present embodiment, the capacitor 70 is usually charged with the output of the booster circuit 50, and when a fast steering operation is performed, the electric charge stored in the capacitor 70 is discharged, and the steering reaction force motor is discharged. A large current is allowed to flow through 13 to suppress an increase in cost.

  Hereinafter, charge / discharge control of the capacitor 70 will be described. The charge / discharge control of the capacitor 70 is performed by executing the steering speed flag setting routine shown in FIG. 9 and the switch switching control routine shown in FIG. 10 in parallel. The steering speed flag setting routine and the switch switching control routine are stored as control programs in the ROM of the steering reaction force ECU 35. The charge / discharge control unit 35b of the steering reaction force ECU 35 starts these two routines by turning on an ignition switch (not shown). Each routine is repeated at a predetermined short cycle by timer interrupt processing.

  The steering speed flag setting routine will be described. When the steering speed flag setting routine is activated, the charge / discharge control unit 35b first detects the actual steering speed ω based on the actual steering angle θ detected by the steering angle sensor 31 in step S31. The actual steering speed ω is obtained by differentiating the actual steering angle θ per unit time, that is, differentiating the actual steering angle θ with respect to time. The actual steering speed ω becomes a positive value when turned counterclockwise and becomes a negative value when turned counterclockwise, but here it is not necessary to distinguish the operation direction and is a parameter for judging the magnitude of the steering speed. Used as Therefore, when determining the magnitude of the actual steering speed ω, the absolute value | ω | is used.

  Subsequently, in step S32, the charge / discharge control unit 35b determines whether or not the actual steering speed | ω | is greater than the set steering speed ω1. The process of step S32 is to determine whether or not a fast steering operation has been performed in the right direction or the left direction. The set steering speed ω <b> 1 is set to a high steering speed that may cause a situation where the energization amount to the steering reaction force motor 13 may be insufficient with the in-vehicle battery 100 alone.

  At the beginning of starting the steering speed flag setting routine, a fast steering operation has not yet been performed. Accordingly, the determination in step S32 is “No”. Based on this determination, the charge / discharge control unit 35b advances the process to step S35, and determines whether or not the steering speed flag Fω is “1”. The steering speed flag Fω is data indicating whether or not a fast steering operation is being performed, as will be understood from the processing described later, and the fast steering operation is represented by Fω = 1 and fast. A situation where the steering operation is not performed is represented by Fω = 0. Further, Fω = 0 is set when the steering speed flag setting routine is started. Therefore, in this case, the determination in step S35 is “No”, and the steering speed flag setting routine is temporarily ended.

  The steering speed flag setting routine is repeated at a predetermined short cycle. Therefore, the above-described processing is repeated while the fast steering operation is not performed. When the fast steering operation is performed and the actual steering speed | ω | exceeds the set steering speed ω1 (S32: Yes), the charge / discharge control unit 35b advances the process to step S33, and the steering speed flag Fω indicates “ Whether or not “0” is determined. Since the steering speed flag Fω is set to “0” at this time, the determination in step S33 is “Yes”. In this case, the charge / discharge control unit 35b sets the steering speed flag Fω to “1” in step S34, and once ends the steering speed flag setting routine.

  The steering speed flag setting routine is repeated at a predetermined short cycle. While the actual steering speed | ω | exceeds the set steering speed ω1 (S32: Yes), the state of the steering speed flag Fω is determined in step S33. It is confirmed. In this case, since the steering speed flag Fω has already been set to “1”, the charge / discharge control unit 35b once ends the steering speed flag setting routine without performing the flag setting.

  When such processing is repeated and the actual steering speed | ω | is reduced to the set steering speed ω1 or less, the determination in step S32 is “No”. In this case, the charge / discharge control unit 35b determines whether or not the steering speed flag Fω is “1” in step S35. Since the steering speed flag Fω is set to “1”, the determination in step S35 is “Yes”, and the process proceeds to step S36. In step S36, the charge / discharge control unit 35b determines whether or not the actual steering speed | ω | has fallen below the set steering speed ω2. The set steering speed ω2 is set to a value smaller than the set steering speed ω1, and is a threshold value for determining whether or not a fast steering operation is finished. Accordingly, since the dead zone (ω2 to ω1) for determining the speed of the steering operation is provided, the determination result is not frequently inverted.

  If the actual steering speed | ω | is not lower than the set steering speed ω2 (S36: No), the charge / discharge control unit 35b ends the steering speed flag setting routine as it is. Therefore, the steering speed flag Fω is maintained at “1”. When the actual steering speed | ω | further decreases and falls below the set steering speed ω2 (S36: Yes), the charge / discharge control unit 35b sets the steering speed flag Fω to “0” in step S37, and the steering speed. The flag setting routine ends.

  The charge / discharge control unit 35b controls the charge / discharge of the capacitor 70 by switching the changeover switch 60 by executing the switch changeover control routine shown in FIG. 10 based on the steering speed flag Fω set in this way.

  In this switch switching control routine, in step S41, the charge / discharge control unit 35b determines whether or not the steering speed flag Fω is “1”, that is, whether or not a fast steering operation is being performed. This determination is made by reading the steering speed flag Fω set in the steering speed flag setting routine described above. If the steering speed flag Fω is “0” (S41: No), the charging / discharging control unit 35b connects the common port O and the selection port A of the changeover switch 60 in step S42, and sets the chargeable mode. Set to. On the other hand, if the steering speed flag Fω is “1” (S41: Yes), in step S43, the common port O and the selection port B of the changeover switch 60 are connected, and the dischargeable mode is set.

  For example, the charge / discharge control unit 35b outputs the signal A to the changeover switch 60 in step S42, and outputs the signal B to the changeover switch 60 in step S43. When the signal A is input, the changeover switch 60 maintains the state if the common port O and the selected port A are in a connected state, and otherwise connects the common port O and the selected port A. Connecting. Further, when the signal B is input, if the common port O and the selected port B are connected, the state is maintained. Otherwise, the common port O and the selected port B are connected.

  The switch switching control routine is repeated at a predetermined short cycle. Therefore, while the fast steering operation is not performed, the chargeable mode is set and the capacitor 70 is charged by the output of the booster circuit 50. Then, when a fast steering operation is performed, the mode is switched to a dischargeable mode, the connection between the capacitor 70 and the charge line 115 is disconnected, and the capacitor 70 and the discharge line 116 are connected. Therefore, the capacitor 70 is connected to the steering reaction force motor drive circuit 37 as an auxiliary power source. The output voltage of the capacitor is the same high voltage as the output voltage of the booster circuit 50 when fully charged. Therefore, a large current can flow through the steering reaction force motor 13 due to the discharge from the capacitor 70, and a large reaction force torque can be applied to the steering handle 11.

  As a result, even when a fast steering operation is performed, an increase in the steering speed of the steering handle 11 is limited to suppress the occurrence of a deviation between the steering operation and the steering of the left and right front wheels FW1, FW2. it can. Further, since it is possible to suppress a shortage of the energization amount to the steering reaction force motor 13 without providing a booster circuit in the previous stage of the steering reaction force motor drive circuit 37, it is possible to implement at a low cost. In addition, when determining the speed of the steering operation, a dead zone (ω2 to ω1) is provided in the determination threshold value, so that the determination result is not frequently inverted, and the switching control of the changeover switch 60 is stabilized. Can be done. The functional unit of the charge / discharge control unit 35b that executes the steering speed flag setting routine corresponds to the steering speed detection means of the present invention, and the functional unit of the charge / discharge control unit 35b that executes the switch switching control routine corresponds to the charging / discharging unit of the present invention. This corresponds to the discharge switching circuit control means.

  Next, a vehicle steering apparatus according to a second embodiment will be described. The vehicle steering apparatus of the second embodiment is different from the steering apparatus of the first embodiment only in charge / discharge control of the capacitor 70. Therefore, here, charge / discharge control of the capacitor 70 will be described. In performing charge / discharge control of the capacitor 70, as shown by broken lines in FIGS. 1 and 2, the detection signal of the turning angle sensor 32 is also input to the steering reaction force ECU 35. Yes.

  Charging / discharging control of the capacitor 70 is performed by executing in parallel a steering speed flag setting routine shown in FIG. 9, a switchback flag setting routine shown in FIG. 11, and a switch switching control routine shown in FIG. Each routine is stored as a control program in the ROM of the steering reaction force ECU 35. The charge / discharge control unit 35b of the steering reaction force ECU 35 starts these three routines by turning on an ignition switch (not shown). Each routine is repeated at a predetermined short cycle by timer interrupt processing. Since the steering speed flag setting routine is the same as that in the first embodiment, the description thereof is omitted.

  Assuming that the quick turning operation and turning operation of the steering handle 11 are repeated, it is necessary to increase the capacity of the capacitor 70, but this is not preferable from the viewpoint of cost. Therefore, in the second embodiment, when there is a possibility that the steering motor 24 is rotated by the self-aligning torque to generate power, the chargeable mode is maintained in preference to the steering speed, and the steering The electric power generated by the motor 24 is regenerated and charged in the capacitor 70.

  The self-aligning torque is generated when the left and right front wheels FW1, FW2 are switched back. Accordingly, in the switch-back flag setting routine shown in FIG. 11, the state where the self-aligning torque is generated is estimated from the change in the actual turning angle δ, and the flag (switching control) used for the switch switching control is based on the estimation. Set the return flag. Hereinafter, the switchback flag setting routine will be described.

  When the switchback flag setting routine is activated, the charge / discharge control unit 35b first reads the detection signal output from the turning angle sensor 32 and detects the actual turning angle δ in step S51. Subsequently, in step S52, it is determined whether or not the left and right front wheels FW1, FW2 are switched back from the amount of change in the actual turning angle δ. The amount of change in the actual turning angle δ is as follows. The actual turning angle δ detected in the current step S51 is δn, and the actual turning angle δ detected immediately before (one control cycle before) is δn-1. (| Δn | − | δn−1 |). When the left and right front wheels FW1, FW2 are switched back to the neutral position, the magnitude (absolute value) of the actual turning angle δ decreases, so the amount of change in the actual turning angle δ takes a negative value. . Therefore, in step S52, it is determined whether or not the actual turning angle change amount (| δn | − | δn−1 |) is smaller than the set value −Δδ. This set value -Δδ is a negative value set in advance. If the actual turning angle change amount (| δn | − | δn−1 |) is smaller than the set value −Δδ, it is determined that the left and right front wheels FW1 and FW2 are switched back. Note that Δn−1 cannot be detected immediately after the start of the switchback flag setting routine, so that it is processed as Δn−1 = Δn.

  At the beginning of the switchback flag setting routine, the left and right front wheels FW1 and FW2 have not been switched back yet. Accordingly, the determination in step S52 is “No”. Based on this determination, the charge / discharge control unit 35b advances the process to step S56 to determine whether or not the switchback flag Fδ is “1”. The switchback flag Fδ is data indicating whether or not the left and right front wheels FW1 and FW2 are switched back, as will be understood from the processing described later. The switchback status is expressed by Fδ = 1, The situation that has not been returned is represented by Fδ = 0. Further, Fδ = 0 is set when the switchback flag setting routine is started. Accordingly, in this case, the determination in step S56 is “No”. Based on this determination, the charge / discharge control unit 35b advances the process to step S55, stores the actual turning angle δn in the RAM as the previous actual turning angle δn−1, and executes the switchback flag setting routine. Exit once.

  The switchback flag setting routine is repeated at a predetermined short cycle. Therefore, δn−1 stored in step S55 is used for the calculation in step S52 in the next control cycle. While the left and right front wheels FW1, FW2 are not switched back, the above-described processing is repeated. When the left and right front wheels FW1, FW2 are switched back and the actual turning angle change amount (| δn |-| δn-1 |) becomes smaller than the set value -Δδ (S52: Yes), the charge / discharge control unit 35b Then, the process proceeds to step S53, and it is determined whether or not the switchback flag Fδ is “0”. Since the switchback flag Fδ is set to “0” at this time, the determination in step S53 is “Yes”. In this case, the charge / discharge control unit 35b sets the switchback flag Fδ to “1” in step S54, and once ends the switchback flag setting routine through the process of step S55.

  The switchback flag setting routine is repeated at a predetermined short cycle, but while the actual turning angle change amount (| δn | − | δn−1 |) is smaller than the set value −Δδ (S52: Yes), step S53. , The state of the switchback flag Fδ is confirmed. In this case, since the switchback flag Fδ is already set to “1”, the charge / discharge control unit 35b temporarily ends the switchback flag setting routine through the process of step S55 without setting the flag. .

  When such processing is repeated and the degree of switching back of the left and right front wheels FW1 and FW2 decreases and the actual turning angle change amount (| δn | − | δn−1 |) increases to a set value −Δδ or more, The determination in S52 is “No”. In this case, the charge / discharge control unit 35b determines whether or not the switchback flag Fδ is “1” in step S56. Since the switchback flag Fδ is set to “1”, the determination in step S56 is “Yes”, and the process proceeds to step S57. In step S57, the charge / discharge control unit 35b determines whether or not the actual turning angle change amount (| δn | − | δn−1 |) exceeds the set value 0 (zero). This step S57 is a process for determining the end of switching back of the left and right front wheels FW1, FW2. Accordingly, the set value to be compared with the actual turning angle change amount (| δn | − | δn−1 |) can be set to an arbitrary value as long as it is larger than −Δδ. Between 0 is a dead zone for the switchback determination process.

  If the actual turning angle change amount (| δn |-| δn-1 |) does not exceed 0 (S57: No), the charge / discharge control unit 35b performs a switchback flag setting routine through the process of step S55. Exit once. Accordingly, the switchback flag Fδ is maintained at “1” as it is. When the actual turning angle change amount (| δn | − | δn−1 |) further increases and exceeds 0 (S57: Yes), the charge / discharge control unit 35b sets the return flag Fδ to “0” in step S58. ”And the process of step S55, the switchback flag setting routine is once terminated.

  The charge / discharge control unit 35b executes the switch switching control routine shown in FIG. 12 on the basis of the switchback flag Fδ set in this way and the steering speed flag Fω described in the first embodiment. 60 is switched to control charging and discharging of the capacitor 70.

  In this switch switching control routine, in step S61, the charge / discharge control unit 35b determines whether or not the switchback flag Fδ is “1”, that is, whether or not the left and right front wheels FW1 and FW2 are switched back. to decide. This determination is made by reading the switchback flag Fδ set in the switchback flag setting routine described above. If the switchback flag Fδ is “1” (S61: Yes), the charging / discharging control unit 35b connects the common port O and the selected port A of the changeover switch 60 to the chargeable mode in step S62. Set.

  On the other hand, if the switchback flag Fδ is “0” (S61: No), it is determined in step S63 whether or not the steering speed flag Fω is “1”. This determination is made by reading the steering speed flag Fω set in the steering speed flag setting routine described above. If the steering speed flag Fω is “0” (S63: No), the charge / discharge control unit 35b connects the common port O and the selected port A of the changeover switch 60 in the above-described step S62, and is in the chargeable mode. If the steering speed flag Fω is “1” (S63: Yes), in step S64, the common port O and the selected port B of the changeover switch 60 are connected and set to the dischargeable mode.

  The switch switching control routine is repeated at a predetermined short cycle. Therefore, if the left and right front wheels FW1, FW2 are switched back, the charging mode is set with priority. When the left and right front wheels FW1, FW2 are switched back, the generated power is often obtained from the steering motor 24 by the self-aligning torque. For this reason, the power generated by the steering motor 24 can be regenerated and charged in the capacitor 70.

  If the left and right front wheels FW1, FW2 are not switched back, the changeover switch 60 is switched according to the speed of the steering operation. While the fast steering operation is not performed, the chargeable mode is set and the capacitor 70 is charged by the output of the booster circuit 50. When a fast steering operation (cutting operation) is performed, the mode is switched to the dischargeable mode, and the capacitor 70 is connected to the steering reaction force motor drive circuit 37 as an auxiliary power source. Therefore, a large current can flow through the steering reaction force motor 13 due to the discharge from the capacitor 70, and a large reaction force torque can be applied to the steering handle 11. Although the dischargeable mode is not set at the time of the return operation, the target steering reaction force at the time of the return operation can be smaller than that at the time of the turn operation, so there is no problem.

  As a result, according to the steering device of the second embodiment, in addition to the effects of the first embodiment, the capacitor 70 can be charged more effectively, and there is no need to increase the capacity of the capacitor 70. It can be implemented at low cost. The function unit of the charge / discharge control unit 35b that executes the switchback flag setting routine corresponds to the switchback detection means of the present invention, and the function unit of the charge / discharge control unit 35b that executes the switch switching control routine corresponds to the charge / discharge control unit of the present invention. This corresponds to the discharge switching circuit control means.

  In the second embodiment, the state where the left and right front wheels FW1, FW2 are switched back by the change of the turning angle δ is detected as the switching back detection means. However, the turning angle δ and the steering angle θ are the above-described turning angles. Since the steering control routine has a one-to-one relationship, the steering wheel 11 may be switched back using the steering angle θ instead of the steering angle δ. In this case, the switchback flag setting routine is as shown in FIG.

  Here, in step S52 ′, it is determined whether or not the switching operation is performed based on whether or not the actual steering angle change amount | θn | − | θn−1 | is smaller than the set value −Δθ (negative value). In step S57 ′, it is determined whether or not the switch back operation has ended based on whether or not the actual steering angle change amount | θn | − | θn−1 | It is processing.

  Next, a vehicle steering apparatus according to a third embodiment will be described. In the third embodiment, when the vehicle speed is less than the set vehicle speed, the electric power generated by the steering motor 24 by the self-aligning torque can be regenerated to the in-vehicle battery 100. As shown in FIG. 13, the vehicle steering apparatus according to the third embodiment includes a changeover switch 62 in the middle of the turning power supply line 112. Hereinafter, the changeover switch 60 used in the first and second embodiments is referred to as a first changeover switch 60, and the changeover switch 62 is referred to as a second changeover switch 62.

  The second changeover switch 62 includes a common port O, a selection port C, and a selection port D. The common port O is connected to the in-vehicle battery 100 side of the steering power supply line 112, and the selection port C is connected to the booster circuit 50 side of the steering power supply line 112. The in-vehicle battery regeneration line 120 is branched from the charging line 115 on the anode side of the diode 117. The end of the in-vehicle battery regeneration line 120 is connected to the selection port D of the second changeover switch 62.

  The second changeover switch 62 is configured to be switchable between a state in which the common port O and the selection port C are connected and a state in which the common port O and the selection port D are connected, and the steering reaction force ECU 35. The switching is controlled by a signal from the charge / discharge control unit 35b. In a state in which the common port O and the selection port C are connected, power is supplied from the in-vehicle battery 100 to the steering motor drive circuit 38 via the booster circuit 50. That is, the circuit configuration is the same as in the first and second embodiments.

  On the other hand, when the second changeover switch 62 is switched and the common port O and the selection port D are connected, the in-vehicle battery 100 and the steered motor drive circuit 38 are directly connected without going through the booster circuit 50. Is done. In this state, power can be supplied from the in-vehicle battery 100 to the steering motor drive circuit 38, and when the steering motor 24 generates power by reverse input, the generated power is regenerated to the in-vehicle battery 100. it can.

  Since the booster circuit 50 cannot flow current in the reverse direction, even when the steering motor 24 is in a power generation state, the power is not regenerated to the in-vehicle battery 100 via the booster circuit 50. Can not. Therefore, hereinafter, the state in which the common port O and the selected port C are connected by the second changeover switch 62 is referred to as a regenerative failure mode, and the state in which the common port O and the selected port D are connected is referred to as a regenerative mode. Call. The second changeover switch 62 and the on-vehicle battery regeneration line 120 correspond to the regeneration switching circuit of the present invention.

  The steering device of the third embodiment includes a vehicle speed sensor 39 as indicated by a broken line in FIG. The vehicle speed sensor 39 outputs a detection signal representing the vehicle speed V to the steering reaction force ECU 35. The charge / discharge control unit 35b of the steering reaction force ECU 35 includes a steering speed flag setting routine shown in FIG. 9, a switchback flag setting routine shown in FIG. 11, a vehicle speed flag setting routine shown in FIG. 14, and a switch shown in FIG. By executing the switching control routine in parallel, charge / discharge control of the capacitor 70 and regeneration control of the in-vehicle battery 100 are performed. Since other configurations are the same as those in the first and second embodiments, different configurations will be described below.

  Since the steering speed flag setting routine and the switchback flag setting routine are the same as those in the second embodiment, description thereof will be omitted, and description will be made from the vehicle speed flag setting routine shown in FIG. Similarly to the other routines, the vehicle speed flag setting routine is started by turning on an ignition switch (not shown), and is repeated at a predetermined short cycle by timer interruption processing.

  When the vehicle speed flag setting routine is activated, the charge / discharge control unit 35b first detects the vehicle speed V by reading the detection signal of the vehicle speed sensor 39 in step S71. Subsequently, in step S72, the charge / discharge control unit 35b determines whether or not the vehicle speed V is greater than the set vehicle speed V1. At the beginning of the start of the vehicle speed flag setting routine, the vehicle speed is still below the set vehicle speed V1. Accordingly, the determination in step S72 is “No”. Based on this determination, the charge / discharge control unit 35b advances the process to step S75, and determines whether or not the vehicle speed flag Fv is “1”. The vehicle speed flag Fv is data indicating whether or not the vehicle is traveling at a speed exceeding the set vehicle speed V1, as will be understood from the processing described later. The vehicle speed flag Fv indicates the situation where the vehicle is traveling at a speed exceeding the set vehicle speed V1. Fv = 1, and a situation where the vehicle is stopped or traveling at a set vehicle speed V1 or less is represented by Fv = 0. The vehicle speed flag Fv is set to Fv = 0 when the vehicle speed flag setting routine is started. Accordingly, in this case, the determination in step S75 is “No”, and the vehicle speed flag setting routine is temporarily ended.

  The vehicle speed flag setting routine is repeated at a predetermined short cycle. Therefore, the above-described processing is repeated while the vehicle speed V does not exceed the set vehicle speed V1. When the vehicle speed V exceeds the set vehicle speed V1 (S72: Yes), the charge / discharge control unit 35b advances the process to step S73, and determines whether or not the vehicle speed flag Fv is “0”. Since the vehicle speed flag Fv is set to “0” at this time, the determination in step S73 is “Yes”. In this case, the charge / discharge control unit 35b sets the vehicle speed flag Fv to “1” in step S74, and once ends the vehicle speed flag setting routine.

  The vehicle speed flag setting routine is repeated at a predetermined short cycle. While the vehicle speed V exceeds the set vehicle speed V1 (S72: Yes), the state of the vehicle speed flag Fv is confirmed in step S73. In this case, since the vehicle speed flag Fv has already been set to “1”, the charge / discharge control unit 35b temporarily ends the vehicle speed setting flag setting routine without performing the flag setting.

  When such processing is repeated and the vehicle speed V decreases to the set vehicle speed V1 or less, the determination in step S72 is “No”. In this case, the charge / discharge control unit 35b determines whether or not the vehicle speed flag Fv is “1” in step S75. Since the vehicle speed flag Fv is set to “1”, the determination in step S75 is “Yes”, and the process proceeds to step S76. In step S76, the charge / discharge control unit 35b determines whether or not the vehicle speed V has fallen below the set vehicle speed V2. The set vehicle speed V2 is set to a value smaller than the set vehicle speed V1, and a dead zone (V2 to V1) for determining the vehicle speed is provided.

  If the vehicle speed V is not less than the set vehicle speed V2 (S76: No), the charge / discharge control unit 35b ends the vehicle speed flag setting routine as it is. Therefore, the vehicle speed flag Fv is maintained at “1” as it is. When the vehicle speed V further decreases and falls below the set vehicle speed V2 (S76: Yes), the charge / discharge control unit 35b sets the vehicle speed flag Fv to “1” in step S77 and ends the steering speed flag setting routine. .

  The charge / discharge control unit 35b executes the switch switching control routine shown in FIG. 15 based on the vehicle speed flag Fv set in this way, the steering speed flag Fω, and the switchback flag Fδ described above, thereby performing the first switching. Switching between the switch 60 and the second changeover switch 62 controls charging / discharging of the capacitor 70 and regeneration to the in-vehicle battery 100.

  In this switch switching control routine, the charge / discharge control unit 35b determines whether or not the vehicle speed flag Fv is “1” in step S81. This determination is made by reading the vehicle speed flag Fv set in the vehicle speed flag setting routine described above. If the vehicle speed flag Fv is “0” (S81: No), the charge / discharge control unit 35b determines whether or not the switchback flag Fδ is “1” in step S82. This determination is made by reading the switchback flag Fδ set in the switchback flag setting routine described above.

  If the switchback flag Fδ is “1” (S82: Yes), the charge / discharge control unit 35b can be charged by connecting the common port O and the selected port A of the first changeover switch 60 in step S83. The mode is set, the common port O of the second changeover switch 62 and the selection port D are connected, and the regenerative mode is set. On the other hand, if the switchback flag Fδ is “0” (S82: No), in step S84, the common port O and the selected port A of the first changeover switch 60 are connected and set to the chargeable mode. The common port O and the selection port C of the second changeover switch 62 are connected to set the regeneration disabled mode.

  When the vehicle speed flag Fv is “1” (S81: Yes), the charge / discharge control unit 35b determines whether or not the switchback flag Fδ is “1” in step S85. If the switchback flag Fδ is “1” (S85: Yes), the charge / discharge control unit 35b can be charged by connecting the common port O and the selected port A of the first changeover switch 60 in step S84. The mode is set, and the common port O and the selection port C of the second changeover switch 62 are connected to set the regeneration disabled mode.

  On the other hand, if the switchback flag Fδ is “0” (S85: No), the charge / discharge control unit 35b determines whether or not the steering speed flag Fω is “1” in step S86. If the steering speed flag Fω is “0” (S86: No), the charge / discharge control unit 35b can be charged by connecting the common port O and the selected port A of the first changeover switch 60 in step S84. The mode is set, and the common port O and the selection port C of the second changeover switch 62 are connected to set the regeneration disabled mode. If the steering speed flag Fω is “1” (S86: Yes), in step S87, the common port O and the selected port B of the first changeover switch 60 are connected and set in the dischargeable mode. The common port O and the selection port C of the second changeover switch 62 are connected to set the regeneration disabled mode.

  The switch switching control routine is repeated at a predetermined short cycle. Thereby, when the vehicle speed V is faster than the set vehicle speed (V1 or V2) (S81: Yes), the regenerative failure mode is always set by the second changeover switch 62. Therefore, since power is supplied from the booster circuit 50 to the steering motor drive circuit 36, it is possible to reliably supply power necessary for driving the steering motor 24. When the vehicle speed V is lower than the set vehicle speed (V1 or V2) (S81: No), the regenerative mode is set only when the left and right front wheels FW1, FW2 are switched back (S82: Yes). The Therefore, the electric power generated by the steering motor 24 by the self-aligning torque can be regenerated to the in-vehicle battery 100. Thereby, consumption of the vehicle-mounted battery 100 can be suppressed. Further, when the left and right front wheels FW1 and FW2 are switched back, even if they are not in a regenerative state, the power required for driving the steering motor 24 can be reduced. Sufficient power can be supplied from 100.

  If the left and right front wheels FW1, FW2 are switched back, the first changeover switch 60 sets the chargeable mode, and the left and right front wheels FW1, FW2 are not switched back and are fast. Only when the steering operation (cutting operation) is being performed (S86: Yes), the discharge enabling mode is set. Accordingly, when it is not necessary to flow a large current to the steering reaction force motor 13, the capacitor 70 is charged by the output of the booster circuit 50, and a quick cutting operation that requires a large current to flow to the steering reaction force motor 13 is performed. Is performed, the power can be supplied from the capacitor 70 to the steering reaction force motor drive circuit 37, so that a large reaction force torque can be applied to the steering handle 11.

  As a result, according to the steering device of the third embodiment, in addition to the effects of the second embodiment, the consumption of the in-vehicle battery 100 can be suppressed. Moreover, since the regenerative mode is set when the vehicle speed is lower than the set vehicle speed, safety is high.

  In addition, the function part of the charging / discharging control part 35b which performs the vehicle speed sensor 39 and vehicle speed flag setting routine in 3rd Embodiment is equivalent to the vehicle speed detection means of this invention, and the charging / discharging control part 35b which performs switch switching control routine is mentioned. The functional unit corresponds to the regeneration switching circuit control means of the present invention.

  As a modification of the third embodiment, the process of step S82 is omitted, and when the vehicle speed flag Fv is “0” (S81: No), the process of step S83 is always performed. Also good. According to this, when the vehicle speed falls below the set vehicle speed, the regenerative disable mode is switched to the regenerative mode by the second changeover switch 62 regardless of whether or not switching is performed.

  As mentioned above, although the vehicle steering apparatus of this embodiment was demonstrated, this invention is not limited to the said embodiment, A various change is possible unless it deviates from the objective of this invention.

  For example, in the present embodiment, the dead zone is provided for the set steering speed, the setting value for determination of switchback, and the set vehicle speed, but the dead zone is not necessarily provided. In the present embodiment, the charge / discharge control unit 35b for controlling the changeover switches 60 and 62 is provided in the steering reaction force ECU 35. However, the charge / discharge control unit 35b may be provided in the steering ECU 36. It may be provided separately from 36.

1 is an overall system configuration diagram of a vehicle steering apparatus according to an embodiment of the present invention. It is a power supply system diagram concerning the 1st-2nd embodiment. It is a flowchart showing the turning angle control routine which concerns on embodiment. It is a graph showing the target turning angle table which concerns on embodiment. It is a flowchart showing the steering reaction force control routine performed by the steering reaction force ECU according to the embodiment. It is a graph showing the spring reaction force torque table which concerns on embodiment. It is a graph showing the friction reaction force torque table which concerns on embodiment. It is a graph showing the viscous reaction force torque table which concerns on embodiment. It is a flowchart showing the steering speed flag setting routine which concerns on 1st-3rd embodiment. It is a flowchart showing the switch switching control routine which concerns on 1st Embodiment. It is a flowchart showing the switchback flag setting routine which concerns on 2nd-3rd embodiment. It is a flowchart showing the switch switching control routine which concerns on 2nd Embodiment. It is a power supply system diagram concerning a 3rd embodiment. It is a flowchart showing the vehicle speed flag setting routine which concerns on 3rd Embodiment. It is a flowchart showing the switch switching control routine which concerns on 3rd Embodiment. It is a flowchart showing the switchback flag setting routine which concerns on a modification.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Steering operation apparatus, 11 ... Steering handle, 12 ... Steering input shaft, 13 ... Steering reaction force motor, 20 ... Steering device, 21 ... Steering shaft, 24 ... Steering motor, 30 ... Electric control device, DESCRIPTION OF SYMBOLS 31 ... Steering angle sensor, 32 ... Steering angle sensor, 33, 34 ... Current sensor, 35 ... Steering reaction force ECU, 36 ... Steering reaction force ECU, 37 ... Steering reaction force motor drive circuit, 38 ... Steering force Motor drive circuit, 50 ... Boost circuit, 60 ... Changeover switch (first changeover switch), 62 ... Second changeover switch, 70 ... Capacitor, 100 ... In-vehicle battery, 115 ... Charge line, 116 ... Discharge line, 120 ... In-vehicle battery Regenerative line.

Claims (5)

A steering motor for steering the steered wheels;
A steering motor drive circuit for driving the steering motor;
A booster circuit provided in a power supply path from a vehicle-mounted power supply to the steering motor drive circuit, boosting an output voltage of the vehicle-mounted power supply and supplying power to the steering motor drive circuit;
Steering control means for controlling the power supply to the steering motor by controlling the steering motor drive circuit in accordance with a steering operation of the steering handle;
A steering reaction force motor for applying a steering reaction force torque to the steering operation of the steering wheel;
A steering reaction force motor drive circuit that is powered from the in-vehicle power supply without going through a booster circuit and drives the steering reaction force motor;
Steering reaction force control means for controlling the steering reaction force motor drive circuit in accordance with a steering operation of the steering handle to control energization to the steering reaction force motor;
A capacitor connected in parallel to the power supply path from the booster circuit to the steered motor drive circuit, charged by the output of the booster circuit, and not allowed to discharge to the steered motor drive circuit ;
A chargeable mode in which the capacitor is connected to the booster circuit to allow charging, and a dischargeable mode in which the capacitor is connected to the steering reaction force motor drive circuit and can be discharged to the steering reaction force motor drive circuit. A charge / discharge switching circuit for switching between
Steering speed detecting means for detecting a steering speed of the steering wheel;
Charge / discharge switching circuit control means for controlling the charge / discharge switching circuit to switch from the chargeable mode to the dischargeable mode when the steering speed detected by the steering speed detection means exceeds a set speed. Steering-by-wire vehicle steering system. A switchback detecting means for detecting switchback of the steering wheel or switchback of the steered wheels;
The charge / discharge switching circuit control means includes:
When the return of the steering wheel or the return of the steered wheel is detected by the switchback detecting means, the chargeable mode is maintained regardless of the steering speed detected by the steering speed detecting means. The vehicle steering apparatus according to claim 1, wherein: A regenerative switching circuit that switches between a regenerative mode that can regenerate the electric power generated by the steering motor to the in-vehicle power source, and a non-regenerative regenerative mode;
Vehicle speed detection means for detecting the vehicle speed;
Regenerative switching circuit control means for controlling the regenerative switching circuit to switch from the non-regenerative mode to the regenerative mode when the vehicle speed detected by the vehicle speed detecting means is less than a set vehicle speed. The vehicle steering apparatus according to claim 1 or 2. A switchback detecting means for detecting switchback of the steering wheel or switchback of the steered wheels;
The regeneration switching circuit control means
When the vehicle speed detected by the vehicle speed detection means is less than the set vehicle speed, and the switchback detection means detects switchback of the steering handle or switchback of the steered wheels, 4. The vehicle steering apparatus according to claim 3, wherein a regeneration switching circuit is controlled to switch from the regeneration impossible mode to the regeneration possible mode. The regeneration switching circuit is
A regenerative path connected to the power input section of the steering motor drive circuit,
In the regenerative mode, disconnect the connection between the in-vehicle power supply and the booster circuit and connect the in-vehicle power supply and the regeneration path,
5. The vehicle steering apparatus according to claim 3, wherein in the regeneration disabled mode, the connection between the in-vehicle power source and the regeneration path is cut off and the in-vehicle power source and the booster circuit are connected.

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