JP2006088867A - Vehicular steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular steering device capable of returning a steering wheel angle to a midpoint even under a condition that road surface reaction torque is smaller than friction torque of a steering mechanism. <P>SOLUTION: A return compensator 27 has a first returning torque compensator 41 computing first returning torque for returning a steering wheel to a neutral position on the basis of the road surface reaction torque and vehicular speed, and a second returning torque compensator 42 computing second torque for returning the steering wheel to the neutral position on the basis of the steering wheel angle and the vehicular speed. When the vehicular speed is smaller than predetermined vehicular speed stored in advance, the returning torque obtained by adding second returning torque to the first returning torque is made to be the output of the return compensator, and when the vehicular speed exceeds the predetermined vehicular speed, the first torque is made to be the output of the return compensator. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle steering apparatus including an electric power steering apparatus, and more particularly to a vehicle steering apparatus including control of a vehicle steering means mounted on an automobile or the like.

  In general, a vehicle driver steers when turning a curved portion or an intersection of a road, and then returns the steering wheel by using a self-returning force of the steering wheel due to a road surface reaction torque of the tire when returning to straight traveling. Perform the operation. However, when the vehicle speed is in a low speed range or in slippery road conditions such as frozen roads, the road surface reaction torque of the tire is weak, so the road surface reaction torque becomes less than the friction torque of the steering mechanism, and when returning straight ahead The handle may not return.

  Therefore, under such circumstances, the driver has to apply torque in the return direction to return the steering wheel to the neutral point, which causes a problem that steering feeling is lowered. On the other hand, in the electric power steering control device provided with the steering wheel angle signal and the steering torque signal, control for returning the steering wheel angle to the neutral point is performed based on the steering torque. (For example, refer to Patent Documents 1 and 2).

  In addition, as control for returning the steering wheel without using the steering wheel angle signal, assist control of the electric power steering is controlled in a direction in which the steering wheel returns at the neutral point according to the steering torque. (For example, refer to Patent Document 3).

  Further, assuming that the steering wheel return control is performed without using the steering torque or the steering wheel angle, the road surface reaction torque generated in the tire is estimated, and the steering wheel is returned to the neutral point according to the road surface reaction torque. ing. (For example, refer to Patent Document 4).

  Furthermore, in estimating the road surface reaction torque, the microcomputer calculates the steering shaft reaction torque based on the outputs from the current detector, steering torque detector, motor angular velocity detector, motor angular acceleration detector, etc. The road surface reaction torque is also estimated based on the above. (For example, refer to Patent Document 5).

JP 2002-331948 A Japanese Patent Laid-Open No. 2003-40130 JP 2002-87300 A JP 2001-122146 A JP 2003-312521 A

  Since conventional vehicle steering means control has been performed as described above, when the vehicle speed of the vehicle to be steered is large and the steering wheel angle is small, sufficient steering wheel angle resolution to perform steering wheel return control cannot be obtained. When the control is performed in such a situation, there is a problem that the steering feeling of the driver is lowered. In addition, when the steering wheel angle signal cannot be obtained due to a failure of the sensor signal, there is a problem that the steering wheel cannot be returned in all areas.

Further, there is a problem that the return compensation is not performed in the region where the steering torque is not generated, and the driver must perform the steering operation himself because the return torque is not generated in the dead zone region of the torque sensor.
Furthermore, although the steering wheel return is improved in areas where the road surface reaction force is small, such as when driving at low speeds, it is not controlled to return the steering wheel angle to the neutral point. There was a problem that could not be controlled.

  The present invention has been made to solve the above-described problems. In the case where the vehicle speed of the vehicle to be steered is large and the steering wheel angle cannot be sufficiently resolved in the region where the steering wheel angle is small, the steering wheel angle cannot be sufficiently resolved. Another object of the present invention is to provide a vehicle steering apparatus that allows a driver to obtain a good steering feeling.

  Another object of the present invention is to provide a vehicle steering apparatus that can perform a steering wheel return control that does not give a driver a sense of incongruity even when a steering wheel angle signal cannot be obtained due to a sensor signal failure or the like.

  Further, the present invention is for a vehicle capable of performing a steering wheel return control in which a steering wheel angle returns to a neutral point without a driver's operation even in a region where a conventional driver has to perform a steering operation himself without generating a steering torque. An object is to provide a steering device.

  A further object of the present invention is to provide a vehicle steering apparatus that can perform a steering wheel return control in which the steering wheel angle returns to a neutral point even in a region where the road surface reaction force is small, such as when traveling at a low speed.

  A vehicle steering apparatus according to the present invention is a vehicle steering apparatus for controlling a motor that generates a torque for assisting a steering of a steering mechanism by a driver, and detects a road surface reaction torque generated on a wheel. Based on a force torque detector, a steering wheel angle detector that detects a steering wheel angle, a vehicle speed detector that detects a vehicle speed, and a detection signal of each of the detectors, at least the steering wheel angle is returned to the neutral position when the driver steers. A return compensator for calculating a return torque to be assisted, wherein the return compensator calculates a first return torque for returning the steering wheel to a neutral position based on the road surface reaction force torque and the vehicle speed. A return torque compensator, and a second return torque compensator for calculating a second return torque for returning the handle to the neutral position based on the handle angle and the vehicle speed, When the vehicle speed is smaller than a predetermined vehicle speed stored in advance, the return compensator uses the return torque obtained by adding the second return torque to the first return torque as the output of the return compensator, and the vehicle speed is the predetermined vehicle speed. When the vehicle speed is greater than the first vehicle speed, the first return torque is used as the output of the return compensator.

  As described above, the vehicular steering apparatus according to the present invention includes the first return compensator based on the vehicle speed and the road surface reaction torque, and the second return compensator based on the vehicle speed and the steering wheel angle. Thus, the desired steering wheel return control can be performed even in a situation where the vehicle speed is low and sufficient road surface reaction force cannot be obtained.

  In addition, even when either the road surface reaction force torque signal or the steering wheel angle signal fails to be obtained by providing the first return compensation torque calculator and the second return compensation torque calculator, Since the output of either one of the return compensators can be obtained, it is possible to minimize the deterioration of the driver's steering feeling.

  Furthermore, the optimum steering wheel return torque can be compensated by compensating the friction torque according to the vehicle speed, and the desired steering wheel return can be performed even when the friction of the steering mechanism changes over time.

  Furthermore, since the angle-dependent friction torque can be compensated, a desired steering wheel return can be performed even under dry asphalt or slippery road conditions.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the overall configuration of a typical vehicle steering system according to the present invention. As shown in this figure, the vehicle steering device system uses a steering gear BOX 3 to multiply the torque added to the output of the motor 5 added to the steering shaft 2 from the steering wheel 1 through the steering shaft 2, and rack and pinion. This is a mechanism for driving the tire 7 through the mechanism 6.

Next, the mechanical and electrical configuration will be described. The vehicle steering device has a main function of generating an assist torque 10 corresponding to the steering torque 9 of the driver.
Electrically, the steering torque 9 when the driver turns the steering wheel 1 is measured by the torque sensor 4, and a signal is sent to the control device 8 as the steering torque detection signal 13. The control device 8 calculates an applied voltage 14 for generating the assist torque 10 based on the current detection signal 15, the voltage detection signal 16, and the steering torque detection signal 13, which are state quantities of the motor 5, and applies it to the motor 5.

  Mechanically, the sum of the steering torque 9 and the assist torque 10 rotates the steering against the steering shaft reaction torque 17. Further, when the handle 1 is rotated, the inertia of the motor 5 also acts, and eventually the following relational expression is established.

T _tran = T _hdl + T _assist -J ・ dω / dt (1)

Here, T _tran is the steering shaft reaction torque, T _hdl is the steering torque, T _assist is the assist torque 10, and J · dω / dt is the motor inertia torque. Further, the assist torque 10 by the motor 5 has the following relationship.

T _assist ＝ G _gear・ K _t・ I _mtr (2)

Where G _gear is the motor gear ratio, K _t is the motor torque multiplier, and I _mtr is the motor drive current. Further, the steering shaft reaction force torque T _tran is the sum of the road surface reaction force torque 12 and the friction torque 11 in the steering mechanism, and is expressed by the following equation.

T _tran = T _align + (G _gear · T _mfric + T _frp ) (3)

Where T _align is the road reaction torque, T _mfric is the motor friction torque, and T _frp is the friction torque in the main steering shaft mechanism excluding the motor.

  In the control device 8 of the vehicle steering device, the current target value is calculated from the above-described sensor signal, and the current control is performed so that the actual current value of the motor 5 coincides with the current value. The torque constant and the gear ratio (between the motor and the steering shaft) are multiplied to generate a predetermined torque to assist the torque when the driver steers. Further, the friction torque Tfric is the sum of the friction torque Ggear / Tmfric of the motor converted to the steering shaft and the friction torque Tfrp in the main steering shaft mechanism excluding the motor.

  An example of the configuration of the vehicle steering apparatus according to the first embodiment is shown in FIG. Although the ECU 8 and the microcomputer 21 have various functions in addition to the constituent elements shown in the figure, only the portions showing the features of the first embodiment are described in this figure. The ECU 8 receives the output signals from the vehicle speed detector 22, the steering torque detector 23, the road surface reaction force detector 24, and the steering wheel angle detector 25, and is calculated by the assist map compensator 26 and the return compensator 27 by the microcomputer 21. The signal is added by an adder 28 to determine a current target value, and the output signal of the motor current detector 31 generated by the motor 32 is added to the adder 29 to determine the control voltage, thereby driving the motor. The motor 30 is driven by the machine 30 to obtain a target assist torque.

  Here, for the microcomputer 21, only the two compensators, the assist map compensator 26 and the return compensator 27 which are relevant in the present invention, are shown as main elements in the electric power steering, but other compensations including inertia compensation are shown. Those having a configuration including a vessel are also known. In the case of a configuration including other compensators, the signals calculated by the respective compensators are added by the adder 28 in the same manner as in the first embodiment, and the addition amount increases. does not change.

  The road surface reaction force torque can be used as a control element by measuring its state quantity by attaching a detector 24 such as a load cell to the tire. However, since the ECU 8 generally includes a current detector, a steering torque detector, a motor angular velocity detector, and a motor angular acceleration detector, it is proposed in Patent Document 5 based on the output signals of these detectors. As described above, it is also possible to obtain an estimated value of the road surface reaction force torque by calculating the steering shaft reaction force torque by the microcomputer.

Even when the ECU 8 does not have a motor angular velocity detector and a motor angular acceleration detector, the motor angular velocity can be obtained by correcting the back electromotive force, and the motor angular acceleration is obtained from the obtained motor angular velocity signal. It can be obtained by differentiating.
In the following embodiments, it is assumed that all the methods described in the first embodiment can be applied to the detection of the road surface reaction force torque.

  The handle angle can be used as a control element by measuring its state quantity by attaching a detector such as a handle angle sensor to the column shaft. Also, it can be obtained from a control ECU of ESC (Electronic Stability Control) through CAN.

  FIG. 3 is a block diagram showing a detailed configuration of the return compensator 27 which is a main component in the configuration of FIG. 2 described above. As shown in this figure, the return compensator 27 includes a first return torque compensator 41 that determines a return amount that improves the driver feeling according to the road surface reaction torque and the vehicle speed, and a vehicle speed that is a constant value. Below, it has the 2nd return torque compensator 42 which calculates the return torque for returning a handle to a neutral point, the output signal of the 1st return torque compensator 41, and the output signal of the 2nd return torque compensator 42 Are added by an adder 43 to generate an output signal of the return compensator. At this time, the output of the adder 43 may be either the target return torque current value or the target return torque value.

  Next, the operation of the return compensator 27 in this embodiment will be described based on the flowchart shown in FIG. First, in step S101, the road surface reaction torque is detected by the road surface reaction torque detector 24 and stored in the memory. Next, in step S102, the handle angle detector 25 detects the handle angle and stores it in the memory. In step S103, the vehicle speed detector 22 detects the vehicle speed and stores it in the memory. Next, in step S104, the first return torque compensator 41 calculates the first return compensation torque based on the relationship between the road surface reaction force torque stored in advance in the microcomputer and the vehicle speed.

In step S105, the second return torque compensator 42 calculates a second return compensation torque based on the relationship between the steering wheel angle and the vehicle speed stored in advance in the microcomputer.
Then, the output signal of the return compensator 27 is calculated by adding the first return compensation torque and the second return compensation torque by the adder 43 in step S106. Through the above process, the output of the return compensator 27 can be obtained in step S107.

  At this time, for example, the second return torque compensator 42 is set so that the second return compensation torque based on the relationship between the steering wheel angle and the vehicle speed stored in the microcomputer in advance is 0 at a vehicle speed of 20 km / h or more. Thus, even when the resolution of the steering wheel angle for performing the steering wheel return control cannot be obtained under a situation where the vehicle speed increases, the return compensation torque can be obtained with the first return compensation torque based on the road surface reaction force torque. .

  In the above example, the output is set to 0 at a vehicle speed of 20 km / h. However, since the magnitude of road surface reaction torque generated differs depending on the vehicle on which the EPS is mounted, the first return torque compensator 41 The output of the second return torque compensator 42 is obtained at the vehicle speed at which the steering wheel return torque expected by the driver can be sufficiently obtained by the first return compensation torque based on the relationship between the road surface reaction torque and the vehicle speed stored in advance in the microcomputer. It is desirable to set 0.

  In addition, even when either the road surface reaction force torque signal or the steering wheel angle signal fails to be obtained by providing the first return torque compensator 41 and the second return torque compensator 42, Since the output of either one of the return torque compensators can be obtained, it is possible to minimize the deterioration of the steering feeling of the driver.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a block diagram illustrating a configuration of the return torque compensator 271 according to the second embodiment. Since the configuration other than the return torque compensator is the same as that of the first embodiment, the description thereof is omitted.

  The difference from the return torque compensator 27 in the first embodiment is the calculation method. That is, in the first embodiment, the output signal of the first return torque compensator 41 and the output signal of the second return torque compensator 42 are added and calculated by the adder 43. Then, the torque signal of the first return torque compensator 41 and the torque signal of the second return torque compensator 42 are switched by the switch 50 based on the vehicle speed signal.

Next, the operation of the second embodiment will be described based on the flowchart shown in FIG.
First, in step S201, the road surface reaction torque is detected by the road surface reaction torque detector 24 and stored in the memory. In step S202, the handle angle detector 25 detects the handle angle and stores it in the memory. Next, in step S203, the vehicle speed is detected by the vehicle speed detector 22 and stored in the memory.

  Next, in step S204, the first return torque compensator 41 calculates the first return compensation torque based on the relationship between the road surface reaction force torque stored in advance in the microcomputer and the vehicle speed. In step S205, the second return torque compensator 42 calculates a second return compensation torque based on the relationship between the steering wheel angle and the vehicle speed stored in advance in the microcomputer. Next, in step S206, the switch 50 selects the first return compensation torque and the second return compensation torque based on the vehicle speed, and either one is used as the output signal of the return compensator 271. Through the above process, the output of the return compensator 271 can be obtained in step S207.

  As described above, according to the second embodiment, it is possible to perform the return torque compensation according to the vehicle speed, so that not only the same effect as in the first embodiment can be aimed but also the setting is performed for each mounted vehicle. Tuning man-hours can be reduced.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 7 is a block diagram illustrating a configuration of the return torque compensator 272 according to the third embodiment. Since the configuration other than the return torque compensator is the same as that of the first embodiment, the description thereof is omitted.

  The difference from the return torque compensator 271 in the second embodiment is that the switch 50 of the second embodiment is different from the first return torque compensator in accordance with the output signal of the friction torque generator 70 corresponding to the vehicle speed stored in advance. This switch is replaced with a switch 71 that switches between the torque signal 41 and the torque signal of the second return torque compensator 42.

  The friction torque in the third embodiment will be described based on the characteristics of the steering wheel angle and the steering shaft reaction torque shown in FIG. In FIG. 8, A shows the steering shaft reaction force characteristic in the low-speed vehicle, and B shows the steering shaft reaction force characteristic in the high-speed vehicle. Further, a represents the friction torque of the steering mechanism in the low speed vehicle, and b represents the friction torque of the steering mechanism in the high speed vehicle.

  Steering is performed in various patterns, and the steering direction of the friction torque Tfric of the steering mechanism is also determined by the steering direction of the driver. That is, the road surface reaction torque Talign including the hysteresis characteristic corresponding to the friction torque Tfric of the steering mechanism corresponds to the steering shaft reaction torque Ttran.

  In general, the friction torque of the steering mechanism is a constant value. When the vehicle speed increases, the hysteresis width of the steering shaft reaction force torque with respect to the road surface reaction force torque is indicated by B in FIG. The friction torque of the steering mechanism becomes small as shown by b. In contrast, when the vehicle speed decreases, the hysteresis width increases as indicated by A in FIG. 8, and the friction torque of the steering mechanism increases as indicated by a.

FIG. 9 is a characteristic diagram showing the relationship between the magnitude of the friction torque of the steering mechanism and the steering wheel return compensation. In this figure, T ₁ indicates the friction torque of the steering mechanism, and T ₂ indicates the compensation torque generated by the first return torque compensator 41. As shown at T _2a in FIG. 9, the magnitude of the first return compensation torque based on the relationship between the road reaction force torque and the vehicle speed stored in the microcomputer in the first return torque compensator 41 in advance is the friction torque. T ₁ is greater than the driver but handle without operating returns to the neutral direction, as shown in the T _2b in FIG. 9, prestored road surface reaction in the first return torque compensator 41 to the microcomputer If the magnitude of the first return compensation torque based on the relationship of the force torque and the vehicle speed is friction torque T ₁ smaller than the driver must return to the operation itself handle to the neutral point.

  Next, the operation of the third embodiment will be described based on the flowchart shown in FIG. First, in step S301, the road surface reaction torque is detected by the road surface reaction torque detector 24 and stored in the memory. Next, in step S302, the handle angle detector 25 detects the handle angle and stores it in the memory. Next, in step S303, the vehicle speed detector 22 detects the vehicle speed and stores it in the memory. Subsequently, in step S304, the first return torque compensator 41 calculates the first return compensation torque based on the relationship between the road surface reaction force torque stored in advance in the microcomputer and the vehicle speed.

Next, in step S305, the second return torque compensator 42 calculates a second return compensation torque based on the relationship between the steering wheel angle and the vehicle speed stored in advance in the microcomputer.
Next, in step S306, the friction torque generator 70 according to the vehicle speed generates a friction torque signal based on the vehicle speed stored in advance in the microcomputer. Thereafter, in step S307, the switch 71 selects the first return compensation torque and the second return compensation torque based on the friction torque, and either one is used as the output signal of the return compensator 272. Through the above process, the output of the return compensator 272 can be obtained in step S308.

  In the above description, the friction torque generator corresponding to the vehicle speed in which the friction torque of the steering mechanism corresponding to the vehicle speed is stored in the microcomputer in advance has been described. However, the situation where the friction torque changes due to secular change of the steering mechanism is also considered. In this case, the microcomputer may be provided with a function of calculating the hysteresis width from the steering shaft reaction force and the steering wheel angle and stored in the memory.

  As described above, according to the third embodiment, it is possible to compensate for the optimum torque for returning the steering wheel by compensating the friction torque according to the vehicle speed. In addition to aiming for the same effect as that of the first embodiment, the friction of the steering mechanism can be reduced. Even in the case of aging, it is possible to realize a desired handle return.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a block diagram showing the configuration of the return torque compensator 273 in the fourth embodiment. Since the configuration other than the return torque compensator is the same as that of the first embodiment, the description thereof is omitted.

  The difference from the return torque compensator 272 in the third embodiment is that the switch 71 of the third embodiment has a first return torque according to the output of the friction torque generator 110 corresponding to the handle angle and the vehicle speed stored in advance. This is a switch 111 that switches between the torque signal of the compensator 41 and the torque signal of the second return torque compensator 42.

The friction torque according to the handle angle in the fourth embodiment will be described based on the characteristics of the handle angle and the friction torque shown in FIG. In FIG. 12, C is the friction torque of the steering mechanism, D ₁ is the road surface reaction torque on the dry asphalt road surface, and D ₂ is the road surface reaction torque on the slippery road surface.

In the description of the third embodiment, although the friction torque of the steering mechanism is constant according to the vehicle speed, the magnitude of the friction torque is actually shown in FIG. 12C according to the position at which the steering wheel operation is performed and the steering wheel angle is generated. Is different. Also, as shown by D ₁ and D ₂ in FIG. 12, the road surface reaction force varies depending on the road surface condition such as the dry asphalt road surface and the slippery road surface even at the same handle angle, so the first based on the road surface reaction force and the vehicle speed. A situation occurs in which the magnitude of the signal of the return torque compensator 41 is different.

  Since the friction torque generator 110 corresponding to the steering wheel angle and the vehicle speed is provided as in the fourth embodiment, and the compensation torque signal is switched according to the output, the angle-dependent friction torque can be compensated. Even under dry asphalt road surfaces and slippery road surface conditions, the steering angle and the vehicle speed are determined by the return compensation torque of the first return torque compensator 41 based on the relationship between the road surface reaction force torque and the vehicle speed stored in advance in the microcomputer. If the steering torque is smaller than the friction torque of the steering mechanism, the steering wheel can be returned to the neutral position by the return compensation torque of the second return torque compensator 42.

Embodiment 5. FIG.
Next, a fifth embodiment of the present invention will be described.
In the fifth embodiment, upper and lower limit values are set for the output change rate with respect to the outputs of the return compensators 27 and 271 to 273 in each of the above-described embodiments.

  In this way, even if there is a large difference in the outputs of the first return torque compensator 41 and the second return torque compensator 42 in the return compensators 27 and 271 to 273, the adder is used in the first embodiment. 43, and in Embodiments 2 to 4, it is possible to assist the driver with the return torque without any sense of incongruity by reducing the sudden change in the return torque signal by the switches 50, 71 and 111.

  As for the torque fluctuation of the return compensator that the driver does not feel uncomfortable, empirically, the upper and lower limits of the output change rate should be about ± 1 Nm / s, and more desirably ± 0.3 Nm / s or less. It is good to do.

  There are various means for setting the upper and lower limit values for the output change rate, such as using a low-pass filter, but since all are well known, detailed description thereof is omitted.

1 is a schematic diagram showing the overall configuration of a typical vehicle steering system according to the present invention. It is a block diagram which shows an example of a structure of Embodiment 1 of this invention. 2 is a block diagram showing a detailed configuration of a return compensator in the first embodiment. FIG. 3 is a flowchart showing the operation of the return compensator in the first embodiment. It is a block diagram which shows the structure of the return compensator in Embodiment 2 of this invention. 10 is a flowchart showing the operation of the return compensator in the second embodiment. It is a block diagram which shows the detailed structure of the return compensator in Embodiment 3 of this invention. FIG. 6 is a characteristic diagram showing a relationship between a steering shaft reaction force according to a general vehicle speed and a friction torque of a steering mechanism. FIG. 6 is a characteristic diagram showing a relationship between a first return compensation torque and a steering function friction torque with respect to a general steering wheel angle in the first embodiment. 10 is a flowchart showing the operation of the return compensator in the third embodiment. It is a block diagram which shows the detailed structure of the return compensator in Embodiment 4 of this invention. FIG. 10 is a characteristic diagram showing a relationship between a first return compensation torque and a steering function friction torque with respect to a general steering wheel angle in the fourth embodiment.

Explanation of symbols

1 steering wheel, 2 steering shaft, 3 steering gear box,
4 Torque sensor, 5 Motor, 6 Rack & pinion shaft, 7 Tire,
8 control device, 9 steering torque, 10 assist torque, 11 friction torque, 12 road surface reaction force torque, 13 steering torque detection signal, 14 applied voltage,
15 current detection signal, 16 voltage detection signal, 17 steering shaft reaction force torque, 21 microcomputer, 22 vehicle speed detector, 23 steering torque detector,
24 road surface reaction force detector, 25 handle angle detector, 26 assist map compensator, 27, 271-273 return compensator,
28 adder, 29 adder, 30 motor driver, 31 motor current detector, 32 motor, 41 first return torque compensator, 42 second return torque compensator, 43 adder, 50 switch based on vehicle speed signal ,
70 Friction torque generator according to vehicle speed, 71 switch,
110 Friction torque generator according to steering wheel angle and vehicle speed, 111 switch.

Claims (6)

  In a vehicle steering apparatus for controlling a motor that generates torque for assisting steering of a steering mechanism by a driver, a road surface reaction force torque detector that detects road surface reaction torque generated on wheels, and a steering wheel angle are detected. A steering angle detector, a vehicle speed detector for detecting a vehicle speed, and a return for calculating a return torque to be assisted to return at least the steering wheel angle to a neutral position at the time of steering by the driver, based on detection signals of the detectors. A return compensator, wherein the return compensator calculates a first return torque compensator for calculating a first return torque for returning the handle to a neutral position based on the road surface reaction torque and the vehicle speed; A second return torque compensator for calculating a second return torque for returning the steering wheel to the neutral position based on the vehicle speed; When the stored vehicle speed is lower than the predetermined vehicle speed, a return torque obtained by adding the second return torque to the first return torque is set as the output of the return compensator. When the vehicle speed is higher than the predetermined vehicle speed, A vehicle steering apparatus characterized in that a first return torque is output from the return compensator.   In a vehicle steering apparatus for controlling a motor that generates torque for assisting steering of a steering mechanism by a driver, a road surface reaction force torque detector that detects road surface reaction torque generated on wheels, and a steering wheel angle are detected. Based on a steering wheel angle detector, a vehicle speed detector for detecting the vehicle speed, and a detection signal from each of the detectors, a return torque to be assisted to return at least the steering wheel angle to the neutral position at the time of steering by the driver is returned. A return compensator, wherein the return compensator calculates a first return torque compensator for calculating a first return torque for returning the handle to a neutral position based on the road surface reaction torque and the vehicle speed; A second return torque compensator for calculating a second return torque for returning the steering wheel to the neutral position based on the vehicle speed, wherein the return compensator Vehicle steering apparatus, characterized in that the output of the first return torque compensator output and the second returning torque compensator of the return compensation device selects either the output.   The return compensator uses the second return torque as the output of the return compensator when the vehicle speed is lower than the predetermined vehicle speed, and the first return torque when the vehicle speed is higher than the predetermined vehicle speed. The vehicle steering apparatus according to claim 1, wherein the output of the return compensator is used as an output.   The return compensator includes a friction torque generator that stores in advance a predetermined value determined according to the vehicle speed as a friction torque of the steering mechanism, and a second return when the first return torque is smaller than the friction torque. 3. The vehicle steering apparatus according to claim 1, wherein the return torque of the torque compensator is used as the output of the previous return compensator.   5. The vehicle steering apparatus according to claim 4, wherein an output signal of the friction torque generator is changed in accordance with a steering wheel angle generated in accordance with a driving operation.   The vehicle steering apparatus according to any one of claims 1 to 5, wherein an upper and lower limit value is set for an output change rate when the output of the return compensator is switched.

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