JP2006160045A - Vehicular steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular steering device capable of correcting any neutral deviation without giving sense of incongruity to a driver. <P>SOLUTION: The vehicular steering device comprises an input shaft connected to a steering wheel, an output shaft which is connected to steered wheels to output the turning quantity, a variable steering angle control mechanism having a steering angle controlling motor capable of changing the ratio of the number of rotation of the input/output shafts, and an electric power steering mechanism which is provided on the output shaft to assist the steering force of the driver, and further comprises a neutral deviation detection means to detect the neutral deviation between the rotational position of the input shaft and the rotational position of the output shaft, a steering angle controlling motor control means to control the steering angle controlling motor so as to maintain the rotational position of the input shaft, and a first neutral deviation correction control means to output the correction control quantity to a power motor based on the neutral deviation detected by the neutral deviation detection means. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle steering apparatus, and more particularly to a vehicle steering apparatus including a variable steering angle mechanism capable of changing a steering angle ratio between a steering wheel and a steered wheel.

  Conventionally, a technique described in Patent Document 1 is known as a vehicle steering apparatus. In the technique described in this publication, a variable steering angle mechanism is disposed on an intermediate shaft that connects a steering shaft connected to a steering wheel and a pinion shaft connected to a pinion of a rack and pinion mechanism. This variable rudder angle mechanism is configured to rotate a pinion shaft (hereinafter referred to as a pinion angle) by adding or subtracting a desired rotation angle by a motor drive when a rotation of the steering shaft (hereinafter referred to as a steering angle) is input. It is said that.

For example, assume that control is performed with an increased pinion angle with respect to the steering angle, and the ignition is turned off while the steering angle is generated. When the steering wheel is operated (steering angle is generated) when this ignition is OFF, the variable steering angle mechanism is stopped, so a pinion angle is generated with a steering angle ratio different from that during variable steering angle control. The neutral position relationship with the corner is shifted (hereinafter referred to as neutral deviation). Therefore, the steering angle and pinion angle are memorized when the ignition is OFF, the neutral deviation is detected by comparing with the steering angle and the pinion angle detected when the ignition is ON, and the neutral deviation is corrected by the motor of the variable steering angle mechanism. It is configured to perform control.
JP 11-171034 A

  However, since the motor of the variable rudder angle mechanism is driven, when there is no load on the steering wheel side, such as in the hand-off state, the steering wheel may be rotated by driving the motor, which may cause the driver to feel uncomfortable.

  The present invention has been made paying attention to the above problem, and an object of the present invention is to provide a vehicle steering apparatus capable of correcting a neutral shift without giving a driver a sense of incongruity.

  In order to achieve the above object, in the vehicle steering apparatus of the present invention, the input shaft connected to the steering wheel, the output shaft connected to the steered wheels and outputting the turning amount, and the input / output shaft rotation speed ratio Steering apparatus for a vehicle, comprising: a variable steering angle control mechanism having a steering angle control motor capable of changing the steering angle; and an electric power steering mechanism having a power motor that is provided on the output shaft and assists the steering force of the driver. A neutral deviation detecting means for detecting a neutral deviation amount between the rotational position of the input shaft and the rotational position of the output shaft, and a rudder for controlling the steering angle control motor so as to maintain the rotational position of the input shaft. Motor control means for angle control, and first neutral deviation correction control means for outputting a correction control amount to the power motor based on the neutral deviation amount detected by the neutral deviation detection means. And it features.

  Therefore, neutral deviation can be corrected without moving the steering wheel.

  Hereinafter, the best mode for realizing the vehicle steering system of the present invention will be described based on a first embodiment shown in the drawings.

  FIG. 1 is a schematic diagram illustrating the configuration of the vehicle steering apparatus according to the first embodiment. A steering shaft 3 is connected to the steering wheel 1. The steering shaft 3 is provided with a steering angle sensor 2 that detects a steering wheel steering angle, and is connected to the upper side of the variable steering angle mechanism 20. A pinion shaft 4 is connected to the lower side of the variable rudder angle mechanism 20. The pinion shaft 4 is provided with a pinion angle sensor 10 that detects a rotation angle of the pinion shaft (corresponding to a turning angle described in claims). An electric power steering mechanism 5 is provided on the pinion shaft 4. A pinion 6 is provided at the lower end of the pinion shaft 4 and meshes with rack teeth formed on the rack shaft 7 to constitute a well-known rack and pinion mechanism.

  The electric power steering mechanism 5 includes a power motor 53 that assists the driver's steering torque, a motor pinion 52 that outputs the driving force of the power motor 53, and a reduction gear that is provided on the pinion shaft 4 and meshes with the motor pinion 52. 51.

  The variable steering angle controller 12 (hereinafter referred to as VGRS controller) includes a steering angle θ detected by the steering angle sensor 2, a pinion angle δ detected by the pinion angle sensor 5, and a vehicle speed detected by the vehicle speed sensor 9. V etc. is input. The variable steering angle controller 12 calculates a steering angle ratio δ / θ representing the ratio of the pinion angle δ to the steering angle θ based on each sensor value, and outputs a control command to the variable steering angle mechanism 20. Instead of the pinion angle sensor 5, the pinion angle δ may be detected by adding or subtracting the detected value of the steering angle sensor 2 using a motor rotation angle sensor or the like mounted on the motor of the variable steering angle mechanism 20. There is no particular limitation.

  The electric power steering controller 13 (hereinafter referred to as an EPS controller) receives the driver's steering torque T detected by the torque sensor 9, the vehicle speed V detected by the vehicle speed sensor 9, and the like. The EPS controller 12 outputs a control command to the power motor 53 based on each sensor value so that the driver's steering torque T becomes a desired value. Although not shown, the power motor 53 is provided with a power motor rotation angle sensor or the like that detects the power motor rotation angle, and motor drive control is executed based on the detection value of the power motor rotation angle sensor. The pinion angle δ may be detected by using a power motor rotation angle sensor or the like instead of the pinion angle sensor 5, and is not particularly limited.

  The VGRS controller 12 and the EPS controller 13 are configured to be able to transmit control information, sensor information, and the like by communication with each other. In addition, when the signals of the steering angle sensor 2, the pinion angle sensor 10, and the torque sensor 9 are input to both controllers, no particular communication is required.

  When the steering wheel 1 is operated by the driver, the rotation of the steering shaft 3 is transmitted to the variable steering angle mechanism 20, and the pinion 6 is rotated by the rotation of the pinion shaft 4 output from the variable steering angle mechanism 20. The rotation of the pinion 6 is converted into the axial movement of the rack shaft 7 to steer the steered wheels 8.

  FIG. 2 is a schematic diagram showing the configuration of the variable steering angle mechanism 20. A spiral cable unit in which a spiral cable having one end fixed to the vehicle body side and wound around the outer periphery of the steering shaft 3 with a margin and then the other end fixed to the steering shaft 3 is mounted on the steering shaft 3 21 is provided. Further, an external gear 24 and a stator 22 constituting a rudder angle control motor 20a (hereinafter referred to as VGRS motor 20a) as an electric actuator are integrally attached to the steering shaft 3. The steering shaft side of the spiral cable is connected to the stator 22 so that power can be supplied to the stator 22 even when the steering shaft 3 rotates.

  A rotor 23 constituting a VGRS motor 20 a is provided on the inner periphery of the stator 22, and the wave generator 26 is driven by the rotor 23. The wave generator 26 has an elliptical cam and can change the positional relationship between the major axis and the minor axis. On the outer periphery of the wave generator 26, a flex spline 27 having metal elastic external teeth is arranged via a bearing. The flex spline 27 is connected to the pinion shaft 4.

  A circular spline 25 having the same number of internal teeth as the external gear 24 is fitted to the outer periphery of the external gear 24 and the flex spline 27, and the rotation of the external gear 24 is transmitted to the flex spline 27. The number of teeth of the flex spline 27 is two more than the number of teeth of the external teeth 24, and only the long diameter portion is fitted to the circular spline 25, and the short diameter portion is not fitted to the circular spline 25.

  When the rotor 23 makes one revolution, the flex spline 27 is elastically deformed by the wave generator 26 to change the positional relationship between the major axis and the minor axis, and a so-called harmonic drive mechanism that increases or decreases the rotation of two teeth is mounted. In addition, a lock mechanism (not shown) is provided, and at the time of failure or when the ignition is OFF, the rotor 23 and the stator 22 are fixed so as to be integrated to achieve a steering angle ratio of 1. The details of the variable rudder angle mechanism 20 are described in, for example, Japanese Patent Application Laid-Open No. 2004-58745, Japanese Patent Application Laid-Open No. 2003-324836, and the like, and thus description thereof is omitted.

  FIG. 3 is a control block diagram showing the configuration of the VGRS controller 12 and the EPS controller 13. The VGRS controller 12 has a steering angle ratio control unit 121 that performs normal steering angle ratio control based on the steering angle θ, pinion angle δ, vehicle speed V, and the like, and neutral deviation correction control while maintaining the steering angle θ. There are provided a first neutral deviation correction control unit 122 that performs the neutral deviation correction control unit 123 that performs neutral deviation correction control when the driver is steering.

  The EPS controller 13 includes a steering assist torque control unit 131 that performs steering assist torque control based on the driver's steering torque T, vehicle speed V, and the like, and a power motor based on a command signal from the first neutral deviation correction control unit 122. The motor rotation number control unit 132 that controls the rotation number 53 is provided.

  FIG. 4 is a control block diagram showing the configuration of the first neutral deviation correction control unit 122. The first neutral deviation correction control unit 122 includes a target steering state amount setting unit 122a for setting a target steering state amount for the steering angle θ and a target turning state amount setting unit for setting a target turning state amount for the pinion angle δ. 122b, a VGRS target motor control amount setting unit 122c that sets a target motor control amount of the VGRS motor 20a, and an EPS target motor control amount setting unit 122d that sets a target motor control amount of the power motor 53.

  The respective target state quantities set by the target steering state quantity setting unit 122b and the target turning state quantity setting unit 122c are output to the respective target motor control quantity setting units 122c and 122d, and the VGRS motor is achieved so as to achieve a desired steering state. 20a and the power motor 53 (motor rotation control unit 132) are driven.

  FIG. 5 is a diagram showing a common speed diagram (hereinafter referred to as a collinear diagram) representing the relationship among the rotational speed of the steering shaft 3, the rotational speed of the pinion shaft 4, and the rotational speed of the rotor 23. In FIG. 5, the upper area represents the rotation speed when steering to the right side, and the lower area represents the rotation speed when steering to the left side. In the variable rudder angle mechanism 20 of the first embodiment, since the steering shaft 3 and the stator 22 rotate integrally, the rotational speed of the rotor 23 is not the rotational speed with respect to the stator 22 but the rotational speed with respect to the vehicle body side. The distance between the vertical axes represents the gear ratio between the rotating elements. The gear ratio between the steering shaft 3 and the pinion shaft 4 when the rotor 23 is not rotated with respect to the vehicle body side is α, and the pinion shaft The gear ratio between 4 and the rotor 23 is β. Hereinafter, the patterns (1) to (4) will be described. For convenience of explanation, the case where the steering shaft 3 is steered to the right will be described, but the same is true when the steering shaft 3 is steered to the left.

〔pattern 1)〕
As shown in (1) in FIG. 5, when the steering shaft 3 is steered to the right side, when the control command for making the steering angle ratio δ / θ larger than 1 is output from the variable steering angle controller 12, the rotor 23 is turned on. The rotation speed is higher than that of the steering shaft 3, and the rotational speed of the pinion shaft 4 is increased more than the rotational speed of the steering shaft 3.

[Pattern (2)]
As shown in (2) in FIG. 5, when the steering shaft 3 is steered to the right side, when the control command for setting the steering angle ratio δ / θ to 1 is output from the variable steering angle controller 12, the rotor 23 is moved to the steering shaft. 3 and the rotation speed of the steering shaft 3 and the rotation speed of the pinion shaft 4 are the same. Since the stator 22 rotates integrally with the steering shaft 3, the rotor 23 is fixed to the stator 22 (the pattern (2) is achieved by the lock mechanism even during a failure).

[Pattern (3)]
As shown in (3) in FIG. 5, when the steering shaft 3 is steered to the right side, when the control command for making the steering angle ratio δ / θ smaller than 1 is output from the variable steering angle controller 12, the rotor 23 is turned on. The rotation speed is lower than that of the steering shaft 3, and the rotational speed of the pinion shaft 4 is decelerated from the rotational speed of the steering shaft 3.

[Pattern (4)]
As shown in (4) in FIG. 5, when the rotation of the pinion shaft 4 is fixed, when the rotor 23 is rotated to the left, the steering shaft 3 is rotated to the right. That is, when the pinion shaft 4 is fixed, the relationship between the rotation direction of the rotor 23 and the rotation direction of the steering shaft 3 is reversed.

  FIG. 6 is a diagram showing the relationship between the steering angle θ and the pinion angle δ. In the variable steering angle mechanism 20, in a non-control state (that is, the same state as a conventional vehicle), the relationship of the pinion angle δ with respect to the steering angle θ is 1: 1, and the steering angle ratio δ / θ = 1 is controlled. For example, in the low vehicle speed region, the steering angle ratio (δ / θ) is reduced in order to reduce the burden on the driver's steering wheel operation. Specifically, control is performed so that a large pinion angle δ is obtained with a small steering angle θ. In the high vehicle speed region, the steering angle ratio (δ / θ) is increased in order to stabilize the vehicle behavior. Specifically, control is performed so that a pinion angle δ smaller than the steering angle θ is obtained.

Here, based on the thick line portion in FIG. 6 and the time chart shown in FIG. 7, the cause of the neutral deviation and the neutral deviation correction control when the neutral deviation occurs will be described.
At time t1, the driver steers from the neutral position to the left, and at this time, the variable steering angle mechanism 20 is controlled at the minimum steering angle ratio.

  At time t2, the driver stops steering at the steering angle θ1. At this time, the rotation angle of the pinion shaft 4 becomes a pinion angle δ1 corresponding to the minimum steering angle ratio.

  When the ignition is turned off at time t3, various controls of the vehicle are ended, so that the control of the variable steering angle mechanism 20 is also ended. The variable rudder angle mechanism 20 has a rudder angle ratio of 1 by fixing the rotor 23 and the stator 22 together by a lock mechanism when the ignition is OFF.

  At time t4, the driver operates the steering wheel 1 in the ignition OFF state, and starts steering in the neutral position direction. At this time, since the rudder angle ratio of the variable rudder angle mechanism 20 is 1, the pinion angle δ rotates at the same rotation angle as the steering angle θ.

  At time t5, the steering angle θ is returned to the neutral position. At this time, the pinion angle δ2 = (δ1−θ1) is satisfied, and the pinion angle is generated regardless of the neutral position of the steering wheel 1, and the neutral deviation occurs.

  When the ignition is turned on at time t6, the steering angle θ and pinion angle δ at this time are read, and neutral deviation has occurred, so neutral deviation correction control is started.

  That is, in the vehicle including the variable rudder angle mechanism 20, neutral deviation occurs due to the above-described action and the like, and therefore, neutral deviation correction control is executed when the ignition is on. Hereinafter, the neutral deviation correction control of the first embodiment will be described.

[Neutral deviation correction control]
FIG. 8 is a flowchart showing neutral deviation correction control.
In step 101, a steering angle ratio is determined from the steering angle θ and the vehicle speed V, and a target pinion angle δ * is calculated based on the steering angle ratio.

  In step 102, a neutral deviation amount Δθ (= δ−δ *) is calculated from the pinion angle δ detected by the pinion angle sensor 10 and the target pinion angle δ *.

  In step 103, it is determined whether or not the absolute value of the neutral deviation amount Δθ is larger than a preset threshold value ΔθT. If it is larger, the process proceeds to step 104. Otherwise, the process proceeds to step 110. Note that the threshold value ΔθT may be set as appropriate as long as it does not give the driver a sense of incongruity, and is not particularly limited.

  In step 104, the neutral deviation correction flag F is set to 1.

  In step 105, it is determined whether or not the absolute value of the vehicle speed V detected by the vehicle speed sensor 11 (because there is a front-rear direction) is larger than a preset threshold value VT. If so, go to Step 106.

  In step 106, it is determined whether or not the absolute value of the pinion angle change amount dδ / dt detected by the pinion angle sensor 10 is smaller than a preset threshold value ΔδT. If smaller, the process proceeds to step 107, and otherwise. Advances to step 111.

  In step 107, it is determined whether or not the steering torque T detected by the torque sensor 9 is larger than a preset threshold value TT. If so, the process proceeds to step 108. Otherwise, the process proceeds to step 109.

  In step 108, a first neutral deviation correction control process for correcting the neutral deviation while maintaining the initial steering angle θinit of the steering angle θ by the control of the VGRS controller 12 and the EPS controller 13 is executed.

  In step 109, a second neutral deviation correction control process is executed in which the neutral deviation is corrected in accordance with the steering speed during steering by the VGRS controller 12, and normal steering torque assist control is executed by the EPS controller 13. . The second neutral deviation correction control process performs the same operation as a known technique (for example, Japanese Patent Laid-Open No. 2000-344121), and a detailed description thereof is omitted.

  In step 110, the neutral deviation correction flag F is set to zero.

  In step 111, a corrected steering angle θh is calculated by subtracting the neutral deviation amount Δθ from the actual steering angle θ detected by the steering angle sensor 2.

  In step 112, normal variable steering angle control using the corrected steering angle θh is executed by the VGRS controller 12, and normal steering torque assist control is executed by the EPS controller 13.

  In step 113, it is determined whether or not the neutral deviation correction flag F is 0. When F = 0, the control flow is terminated, and otherwise, the process proceeds to step 114.

  In step 114, the neutral deviation amount Δθ is added again to the corrected steering angle θh, and the steering angle θ is returned to the steering angle sensor value, which is used for calculation of the neutral deviation amount Δθ in the next control cycle.

[Operation of neutral deviation correction control]
The operation of the control flow will be described.
(1) When neutral deviation correction control is not performed (Condition 1) When the neutral deviation amount Δθ is calculated and the absolute value of the neutral deviation amount Δθ is equal to or less than a preset threshold value ΔθT.

  That is, when the neutral deviation amount Δθ is small, the steering angle θ and the pinion angle δ coincide with each other, so that the driver does not feel uncomfortable, so that neutral deviation correction is not particularly required. Therefore, normal steering angle ratio control and steering torque assist control are executed.

  (Condition 2) When the absolute value of the vehicle speed V detected by the vehicle speed sensor 11 (because there is a front-rear direction) is greater than a preset threshold value VT.

  That is, if the vehicle is traveling, the pinion angle δ change not intended by the driver may occur due to the neutral deviation correction control, which may affect the vehicle behavior. Therefore, when it is determined that the vehicle is running, neutral deviation correction control is not performed, and normal steering angle ratio control and steering torque assist control are performed.

  (Condition 3) The absolute value of the pinion angle change amount dδ / dt detected by the pinion angle sensor 10 is smaller than a preset threshold value ΔδT.

  That is, when the neutral deviation correction control is performed, either the first neutral deviation correction control or the second neutral deviation correction control is performed. In the first neutral deviation correction control in the first embodiment, both the VGRS motor 20a and the power motor 53 are controlled so as to maintain the initial steering angle θinit. At this time, for example, if a state occurs in which the steered wheel 8 is in contact with the curb or the like and cannot be steered, the rotation of the power motor 53 is stopped, and the absolute value of the pinion angle change amount dδ / dt is set to a preset threshold value ΔδT. Smaller than. At this time, if the first neutral deviation correction control is continued, useless current consumption occurs by the power motor 53. Therefore, at this time, the normal steering angle ratio control and the steering torque assist control are performed using the corrected steering angle θh, so that the driver's steering intervention is awaited, and there is no obstacle such as a curb during or after the steering intervention. In the state, the second neutral deviation correction control is performed. This achieves neutral deviation correction without any sense of incongruity.

(2) When neutral deviation correction control is performed When each of the above conditions 1 to 3 is not satisfied, the first neutral deviation correction control or the second neutral deviation correction control is performed depending on whether or not the following (condition 4) is satisfied. (Corresponding to the switching means described in the claims).

  (Condition 4) When the steering torque T detected by the torque sensor 9 is greater than a preset threshold value TT, the second neutral deviation correction control is performed, and otherwise, the first neutral deviation correction control is performed. .

  That is, when the steering torque T is generated, it is a state in which the driver is steering, so it is not necessary to perform the first neutral deviation correction control for maintaining the initial steering angle θinit. Therefore, at this time, the second neutral deviation correction control is executed. Further, when the steering torque T is not generated, it is considered that the driver is not keeping the steering wheel 1, and if the steering wheel 1 rotates in this state, there is a possibility of giving a sense of incongruity. Therefore, at this time, the first neutral deviation correction control that maintains the initial steering angle θinit is executed.

[About the first neutral deviation correction control]
Next, the first neutral deviation correction control according to the first embodiment will be described. When the neutral deviation amount Δθ is detected, the EPS target motor control amount setting unit 122d sets the number of rotations of the power motor 53 according to the neutral deviation amount Δθ and controls the rotation by the EPS controller 13. On the other hand, in the VGRS target motor control amount setting unit 122c, feedback control is performed so as to maintain the initial steering angle θinit, that is, the steering angle change amount is equal to or less than a predetermined value.

  Thus, by operating the VGRS motor 20a and the power motor 53 simultaneously, neutral deviation correction control can be achieved while suppressing the movement of the steering wheel 1 as much as possible. In controlling the VGRS motor 20a and the power motor 53, it is desirable to reduce the torque output from the VGRS motor 20a as much as possible. That is, since the stator 22 is fixedly supported on the steering shaft 3, if the inertia of the steering wheel 1 and the steering shaft 3 is greatly exceeded, the steering wheel 1 may move due to the reaction torque.

Next, the effect will be described. In the vehicle steering angle control device of the first embodiment, the effects listed below can be obtained.
(1) In the vehicle steering system in which the steering wheel 1, the VGRS motor 20a, the power motor 53, and the pinion shaft 4 for turning the steered wheels 8 are connected on the nomograph, the target of the steering wheel 1 Target steering state quantity setting unit 122a for setting the steering state quantity, target steering state quantity setting part 122b for setting the target turning state quantity of the pinion shaft 4, and target steering set by the target steering state quantity setting part 122a Target motor control amount setting units 122c and 122d for setting control amounts of the VGRS motor 20a and the power motor 53 based on the state amount and the target turning state amount set by the target turning state setting unit 122b are provided. .

  Therefore, the target turning state quantity can be controlled based on the target steering state quantity by the two actuators of the VGRS motor 20a and the power motor 53 arranged on the alignment chart.

  (2). The target turning state amount setting unit 122a sets the pinion shaft rotation speed W1 that is the target turning state amount based on the initial steering angle θinit that is the steering state amount of the steering wheel 1.

  Thereby, the neutral deviation can be corrected while maintaining the initial steering angle θinit within the range of the slight movement of the steering wheel 1. Further, by rotating only the VGRS motor 20a as described in the above condition 3, it is possible to prevent the driver from feeling uncomfortable due to the steering wheel 1 rotating.

  Next, Example 2 will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described. In the first embodiment, the VGRS motor 20a is controlled to be maintained at the initial steering angle θinit by feedback control. In contrast, the second embodiment is different from the feedback control in that the control amount of the VGRS motor 20a is set in advance based on the neutral deviation amount Δθ.

  Next, neutral deviation correction control according to the second embodiment associated with the above control will be described. FIG. 9 is a flowchart illustrating neutral deviation correction control according to the second embodiment. Since steps 101 to 105 and steps 107 to 114 are the same as those in the first embodiment, only different steps will be described.

  In step 206, it is determined whether or not the absolute value θ ′ of change in the steering angle θ detected by the steering angle sensor 2 from the initial steering angle θinit is larger than a preset threshold value θT. Proceed, otherwise proceed to step 111.

  That is, when the neutral deviation correction control is performed, either the first neutral deviation correction control or the second neutral deviation correction control is performed. In the first neutral deviation correction control in the second embodiment, both the VGRS motor 20a and the power motor 53 are controlled so as to maintain the initial steering angle θinit. At this time, for example, if the steered wheel 8 comes into contact with a curb or the like and cannot be steered, the rotation of the power motor 53 is stopped. At this time, only the VGRS motor 20a rotates. If the VGRS motor 20a rotates in this state, there is a possibility that the initial steering angle θinit cannot be maintained. At this time, normal steering angle ratio control and steering torque assist control are performed using the corrected steering angle θh, so that the driver is on standby for steering intervention, and the second neutral deviation correction control is performed during steering intervention. Achieving neutral deviation correction without noise.

[About the first neutral deviation correction control]
Next, the first neutral deviation correction control according to the second embodiment will be described. As described with reference to the collinear diagram of FIG. 5, since the steering wheel 1 and the steering wheel 8 are mechanically coupled, the relationship of the rotational speed is defined by a straight line. Therefore, in order to rotate the pinion angle δ to the target pinion angle δ * while maintaining the initial steering angle θinit, the rotational speed of the rotor 23 is increased more than the rotational speed of the pinion shaft 4 as shown in FIG. You can do it.

  First, in the target steering state quantity setting unit 122a, the steering angle θ = initial steering angle θinit (that is, steering angular speed = 0) is set as the target steering state quantity. Next, in the target turning state amount setting unit 122b, the rotation speed W1 of the pinion shaft 4 corresponding to the neutral deviation amount Δθ is set. Next, the EPS target motor control amount setting unit 122d sets the control amount of the power motor 53, and the motor rotation control unit 132 of the EPS controller 13 drives the power motor 53. At the same time, a value (α + β) W1 obtained by multiplying the pinion shaft rotational speed W1 by the gear ratio (α + β) is set in the target turning state amount setting unit 122b, and the VGRS target motor control amount setting unit 122c controls the VGRS motor 20a. The amount is set and drives the VGRS motor 20a.

  Thus, neutral deviation correction can be achieved while maintaining the initial steering angle θinit. Moreover, since the rotation speed of the VGRS motor 20a is set in advance, the movement of the steering wheel 1 can be further suppressed. Note that the configuration of the first neutral deviation correction control unit 122 is, in other words, a configuration in which the steering angle θ and the pinion angle δ can be freely controlled by two motors. Therefore, the present invention is not limited to neutral deviation correction control, and may be applied to control during normal traveling.

  Next, Example 3 will be described. Since the basic configuration is the same as that of the first embodiment, only different points will be described.

  FIG. 11 is a schematic diagram illustrating the configuration of the variable rudder angle mechanism 60 of the third embodiment. The variable rudder angle mechanism 60 has a first sun gear S1 connected to the steering shaft 3 and a first planetary gear G1 including a first pinion P1 meshing with the first sun gear S1. The second planetary gear G2 includes a second sun gear S2 connected to the pinion shaft 4 and a second pinion P2 meshing with the second sun gear S2. Further, it is composed of a carrier C1 that rotatably supports both the first pinion P1 and the second pinion P2, and a VGRS motor 61 that meshes with the carrier C1. The VGRS motor 61 is fixedly supported on the vehicle body side, and meshes with the carrier C1 by the VGRS motor pinion 61a and the gear Ca so as to have a rotational speed ratio λc.

  FIG. 12 is a collinear diagram showing the relationship between the rotational speeds of the rotating elements of the variable steering angle mechanism 60 of the third embodiment. The rotation speed of the first sun gear S1 is Ns1, the rotation speed of the second sun gear S2 is Ns2, the rotation speed of the carrier C1 is Nc1, and the rotation speed ratio between the first sun gear S1 and the second sun gear S2 is λ.

The above relationship is expressed by the following formula.
(Formula 1)
(Ns2-Nc) = λ (Ns1-Nc)

In the first neutral deviation correction control unit 122, since the steering wheel 1 is controlled to maintain the initial steering angle θinit in the target steering state amount setting unit 122a, the target steering state amount of the first sun gear S1 becomes zero. At this time, the relationship between the rotational speeds of the second sun gear S2 and the carrier C1 is expressed by the following relational expression.
(Formula 2)
Nc1 = {1 / (1-λ)} × Ns2

At this time, since the power motor 53 is connected to the pinion shaft 4 via the reduction gear 51, the rotational speed Ne transmitted from the power motor 53 to the pinion shaft 4 in consideration of the reduction ratio of the reduction gear 51 is It is equal to the rotation speed of 2 sun gear S2.
(Formula 3)
Ns2 ＝ Ne

The rotational speed Nc of the carrier C1 and the rotational speed Nv of the VGRS motor 61 are expressed by the following relational expression.
(Formula 4)
Nv = (− 1 / λc) × Nc

From the above formulas (2) to (4), the relationship between the rotational speeds of the VGRS motor 61 and the power motor 53 is expressed by the following formula.
(Formula 5)
Nv = {− 1 / (λc (1-λ))} × Ne

  The relationship between the rotational speeds of the rotating elements is defined as described above.

Next, the relationship between the torques of the rotating elements will be described. The relationship between the rotational torques Tc and Ts2 between the carrier C1 and the second sun gear S2 is expressed by the following equation.
(Formula 6)
Tc = (1-λ) × Ts2

At this time, the rotational speed Ts2 of the second sun gear S2 is given from the power motor 53. Since the sun gear S2 and the power motor 53 are integrated, when the torque transmitted from the power motor 53 considering the reduction gear 51 to the pinion shaft 4 is Te, it is expressed by the following equation.
(Formula 7)
Ts2 ＝ Te

The rotational torque Tc of the carrier C1 is expressed by the following equation with the rotational torque Tv of the VGRS motor 61.
(Formula 8)
Tv = −λc × Tc

Therefore, the relationship between the rotation torque Tv of the VGRS motor 61 with respect to the torque Te of the power motor 53 is expressed by the following equation by the equations (6) to (8).
(Formula 9)
Tv = −λc × (1-λ) × Te
The above relationship is set by the first neutral deviation correction control unit 122.

  The reaction force of the torque applied from the VGRS motor 61 to the carrier C1 is received by the vehicle body side support point of the VGRS motor 61. The torque Te of the power motor 53 is a torque that is finally given from the pinion shaft to the second sun gear S2 by offsetting with the steering reaction torque given from the steered wheels 8 to the pinion 6, and the steering reaction force torque Needless to say, most of the power is received by the support point on the vehicle body side of the power motor 53.

  Therefore, the rotational speed and rotational torque of the VGRS motor 61 and the power motor 53 in the VGRS target motor control amount setting unit 122c and the EPS target motor control amount setting unit 122d so as to satisfy the relationship of the above formulas (5) and (9). Are controlled simultaneously.

  In the first and second embodiments, since the VGRS motor 20a of the variable steering angle mechanism 20 is fixedly supported with respect to the steering shaft 3, only the rotation speed is controlled to restrict the movement of the steering wheel 1. Therefore, since the steering shaft 3 picks up the motor reaction force when the VGRS motor 20a is driven, there is a possibility that the steering wheel 1 may move slightly (there is an inertia of the steering wheel 1 and the range of this inertia) If it is controlled within, no problem.)

  On the other hand, in Example 3, since the VGRS motor 61 is supported on the vehicle body side, the steering shaft 3 does not receive a motor reaction force when the VGRS motor 61 is driven. Therefore, it is possible to simultaneously control the rotation speed and torque of each rotating element, and the pinion shaft 4 can be rotated so that the steering shaft 3 does not move at all. Therefore, the neutral shift can be corrected without giving the driver a sense of incongruity.

  Although the third embodiment has been described by focusing on the point of correcting the neutral deviation, the above logic may be applied to normal steering control. For example, a steering torque is set as a steering state quantity from the steering angle θ and steering angular velocity dθ / dt of the driver, and the target turning state quantity is achieved so as to achieve this steering state quantity (steering angle θ and steering torque T). The pinion angle δ, the pinion angular velocity dδ / dt, and the pinion torque are set. The rotational speed and torque of the VGRS motor 61 and the power motor 53 may be controlled based on the set steering state amount and steered state amount.

  Thereby, the steering state of the steered wheels 8 can be freely set while setting the steering state of the driver according to the traveling state. In addition, since the rotational speed and torque of each rotating element are controlled simultaneously, it is possible to avoid a situation in which the torque input of the VGRS motor 61 and the power motor 53 bounces back to the driver side and gives a sense of incongruity.

  As mentioned above, although the vehicle steering device of the present invention has been described based on the first to third embodiments, the specific configuration is not limited to these embodiments, and the invention according to each claim of the claims. Design changes and additions are permitted without departing from the gist of the present invention. For example, in the third embodiment, the planetary gears G1 and G2 are used as the variable rudder angle mechanism 60. However, a steering unit that combines the variable rudder angle mechanism and the power assist function is mounted and controlled by this steering unit. You may do it. For example, using a Ravigneaux type planetary gear having four rotating elements, the steering wheel 1, the pinion shaft 4, the VGRS motor 61, and the power motor 53 are connected to each rotating element, and the steering state amount and the steered state are connected. The amount may be freely controlled. Alternatively, a steering unit may be configured using a Simpson type or a double sun gear type, and the steering state quantity and the steered state quantity may be freely controlled by connecting to each rotating element.

1 is a schematic diagram illustrating a configuration of a vehicle steering apparatus according to a first embodiment. FIG. 3 is a schematic diagram illustrating a configuration of a variable steering angle mechanism according to the first embodiment. FIG. 3 is a control block diagram illustrating configurations of a VGRS controller and an EPS controller according to the first embodiment. FIG. 3 is a control block diagram illustrating a configuration of a first neutral deviation correction control unit according to the first embodiment. FIG. 6 is a collinear diagram showing the relationship among the rotation speed of the steering shaft, the rotation speed of the pinion shaft, and the rotation speed of the rotor according to the first embodiment. FIG. 6 is a diagram illustrating a relationship between a steering angle θ and a pinion angle δ according to the first embodiment. 6 is a time chart showing factors that cause neutral deviation in the first embodiment. 6 is a flowchart illustrating neutral deviation correction control according to the first embodiment. 10 is a flowchart illustrating neutral deviation correction control according to the second embodiment. FIG. 10 is a nomographic chart in first neutral deviation correction control of Embodiment 2. FIG. 6 is a schematic diagram illustrating a configuration of a variable steering angle mechanism according to a third embodiment. FIG. 10 is a collinear diagram showing the relationship between the rotational speeds of the rotating elements of the variable rudder angle mechanism of the third embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering wheel 2 Steering angle sensor 3 Steering shaft 4 Pinion shaft 5 Electric power steering mechanism 6 Pinion 7 Rack shaft 8 Steering wheel 10 Pinion angle sensor 11 Vehicle speed sensor 12 VGRS controller 13 EPS controller 20 Variable steering angle mechanism 20a For steering angle control Motor (VGRS motor)
53 Power motor 60 Variable steering angle mechanism 61 Steering angle control motor (VGRS motor)

Claims (11)

An input shaft connected to the steering wheel;
An output shaft connected to the steered wheels and outputting the steered amount;
A variable rudder angle control mechanism having a rudder angle control motor capable of changing the input / output shaft rotation speed ratio;
An electric power steering mechanism provided on the output shaft and having a power motor for assisting a driver's steering force;
In a vehicle steering apparatus comprising:
A neutral deviation detecting means for detecting a neutral deviation amount between the rotational position of the input shaft and the rotational position of the output shaft;
Rudder angle control motor control means for controlling the rudder angle control motor so as to maintain the rotational position of the input shaft;
First neutral deviation correction control means for outputting a correction control amount to the power motor based on the neutral deviation amount detected by the neutral deviation detection means;
A vehicle steering apparatus characterized by comprising: The vehicle steering apparatus according to claim 1,
A steering angle detecting means for detecting a rotational position of the input shaft is provided;
The steering angle control motor control means controls the steering angle control motor so that the amount of change in the steering angle detected by the steering angle detection means is a predetermined value or less. . The vehicle steering apparatus according to claim 1,
The steering angle control motor control means controls the steering angle control motor based on the neutral deviation amount detected by the neutral deviation detection means. A plurality of rotating elements connected via a predetermined reduction ratio are indicated by lines arranged in parallel with an inter-axis distance set according to the reduction ratio between the respective rotating elements, and the interval between these lines. A steering wheel, a first motor, a second motor arranged on a line different from the first motor, and a steered wheel are steered on a common speed diagram indicating the direction and the rotation speed of each rotating element. In a vehicle steering apparatus to which a steering output element is connected,
Target steering state amount setting means for setting a target steering state amount of the steering wheel;
Target turning state amount setting means for setting a target turning state amount of the output element for turning based on the target steering state amount;
Based on the target steering state quantity set by the target steering state quantity setting means and the target steering state quantity set by the target steering state setting means, the control amounts of the first motor and the second motor are determined. Target motor control amount setting means to be set;
A vehicle steering apparatus characterized by comprising: The vehicle steering device according to claim 4,
A steering angle detection means for detecting the steering angle of the steering wheel is provided,
The vehicle steering apparatus according to claim 1, wherein the target steering state quantity setting means sets a target steering state quantity based on the steering angle detected by the steering angle detection means. In the vehicle steering device according to claim 4 or 5,
The vehicle steering apparatus according to claim 1, wherein the target steering state quantity setting means is means for setting a steering torque of the steering wheel as a target steering state quantity. The vehicle steering apparatus according to any one of claims 4 to 6,
The target steering state quantity setting means sets an initial steering state quantity when the vehicle steering apparatus is activated as the target steering state quantity. In the vehicle steering device according to claim 6 or 7,
The target steering state amount setting means sets a steering torque of the steering wheel as a target steering state amount to a predetermined value or less. The vehicle steering apparatus according to any one of claims 1 to 8,
Operation state detection means for detecting whether or not the steering wheel is operated by the driver;
Second neutral deviation correction control means for performing neutral deviation correction only by the steering angle control motor;
When the neutral deviation is detected by the neutral deviation detecting means and the operation state is detected by the steering state detecting means, correction control by the second neutral deviation correction control means is executed, and otherwise, the first deviation is detected. Switching means for executing correction control by one neutral deviation correction control means;
A vehicle steering apparatus characterized by comprising: In the vehicle steering apparatus in which at least a steering wheel, a first motor, a second motor, and a steering output element for steering a steered wheel are connected on the alignment chart,
A target steering state amount of the steering wheel is set, a target turning state amount of the steering output element is set based on the target steering state amount, and the target steering state amount and the target turning state amount are set. A vehicle steering apparatus characterized in that the control amount of the first motor and the second motor is set on the basis of the control amount. An input shaft connected to the steering wheel;
An output shaft connected to the steered wheels and outputting the steered amount;
A variable rudder angle control mechanism having a rudder angle control motor capable of changing the input / output shaft rotation speed ratio;
An electric power steering mechanism provided on the output shaft and having a power motor for assisting a driver's steering force;
In a vehicle steering apparatus comprising:
A neutral shift amount between the rotational position of the input shaft and the rotational position of the output shaft is detected, the steering angle control motor is controlled so as to maintain the rotational position of the input shaft, and based on the neutral shift amount A vehicle steering apparatus that outputs a correction control amount to the power motor.

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