JP2009298338A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device capable of performing a comfortable steering wheel operation even if a driver operates the steering wheel at a high speed when a quick ratio is set in a slow vehicle speed range. <P>SOLUTION: This steering device 1 changes a transmission ratio of a steering angle of a steering wheel 2 in respect to the steering angle of the steering wheel by a variable transmission ratio mechanism 5, and generates an assisting force applied at the time of steering operation by an electric power steering device 4. The device 1 comprises a variable transmission ratio mechanism controlling ECU 9 having a changing-over means for changing-over a transmission ratio adjustment mode for setting a rotational angle of a motor 33 for variable transmission ratio used in the variable transmission ratio mechanism 5 and a steering torque adjustment mode for reducing an electric current for driving the motor 33 for variable transmission ratio so as to cause a steering force of the steering wheel 2 to be reduced. Then, the electric current is controlled continuously at the time of the above changing-over operation. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a steering device that changes a transmission ratio of a steering angle of a steering wheel to a turning angle of a steered wheel by a variable transmission ratio mechanism, and generates an assisting force during steering by electric power steering.

  Conventionally, a steering apparatus including a variable transmission ratio mechanism and an electric power steering has been proposed. According to the variable transmission ratio mechanism, by setting the transmission ratio (= steering wheel angle / steering angle) to a small (quick ratio) in a low vehicle speed range such as when parking, etc. Since the vehicle can be steered greatly, the operation burden on the driver can be reduced and the convenience can be improved.

  At high vehicle speeds, the transmission ratio is set to a large value (slow ratio), so even if the steering wheel is steered greatly, the steered wheels only turn slightly, improving the yaw rate response characteristics and improving the running stability of the vehicle. Can be improved. Moreover, according to the electric power steering, since the steering assist force is generated, the steered wheels can be steered only by lightly operating the steering handle.

  In a steering device equipped with such a variable transmission ratio mechanism and electric power steering, when a quick ratio is achieved in a low vehicle speed range, if the driver tries to turn the steering wheel with fast steering, in electric power steering, An attempt is made to generate auxiliary force so that the steering wheel can be steered large and fast, but the EPS (Electric Power Steering) motor (assist motor), which is the power source of electric power steering, has insufficient auxiliary force due to the effect of the back electromotive force. The steering force may become heavy.

Therefore, in such a case, the target transmission ratio that is the target value of the transmission ratio is changed in real time so that the transmission ratio is changed in the direction of the slow ratio, thereby avoiding an increase in steering force. A technique has been proposed (see, for example, Patent Document 1).
JP 2000-344120 A

However, in the conventional method, for example, a phenomenon in which the steering reaction force fluctuates in response to the steering operation of the steering wheel such as fast-slow-fast, or the steering handle is rotated at a rapid and large steering speed. At the beginning, it was considered that a phenomenon may occur in which the steering reaction force increases at the beginning of the steering operation, and the steering of the steering wheel is caught and becomes stuffy.
When these phenomena occur, the driver may feel uncomfortable with the operation feeling of the steering wheel.

  In addition, when the steering wheel is turned at a large steering speed, the driver may not be able to quickly follow the target transmission ratio due to the output torque of the transmission ratio variable motor used in the variable transmission ratio mechanism. Even after the steering operation of the steering wheel is finished, there is a risk that the steering wheel may feel uncomfortable, such as turning the steered wheel in the previous steering direction.

  Accordingly, an object of the present invention is to provide a steering device that can perform comfortable steering even when the driver turns the steering wheel at a high steering speed when the quick ratio is achieved in a low vehicle speed range.

The invention according to claim 1 is a steering device in which the transmission ratio of the steering angle of the steering wheel with respect to the steered angle of the steered wheels is changed by a variable transmission ratio mechanism, and the assisting power at the time of steering is generated by electric power steering. The transmission ratio adjustment mode for setting the rotation angle of the variable transmission ratio motor used in the variable transmission ratio mechanism and the steering force of the steering wheel are reduced so that the transmission ratio is set to the target transmission ratio corresponding to the vehicle speed. And a switching means for switching between a steering torque adjustment mode for reducing a current for driving the transmission ratio variable motor,
When switching from the transmission ratio adjustment mode to the steering torque adjustment mode, control is performed such that the current value to the transmission ratio variable motor continuously changes.

  According to the first aspect of the present invention, since the transmission ratio can be set to the target transmission ratio corresponding to the vehicle speed by the transmission ratio adjustment mode, the target transmission ratio is reduced (quick ratio) in the low vehicle speed range. By setting and controlling the transmission ratio to match the target transmission ratio, the transmission ratio can be made quick. In a high vehicle speed range, the transmission ratio can be reduced by setting the target transmission ratio to a large value (making it a slow ratio) and controlling the transmission ratio to match the target transmission ratio.

Also, when the quick ratio is achieved in the low vehicle speed range, if the driver turns the steering wheel with fast steering, the switching means switches from the transmission ratio adjustment mode to the steering torque adjustment mode and drives the transmission ratio variable motor. The steering reaction force of the steering wheel can be reduced by adjusting the current.
Specifically, in the switched steering torque adjustment mode, the steering reaction force is influenced by the current that drives the transmission ratio variable motor, but this current is adjusted so as to reduce the steering torque value. For example, the steering reaction force does not fluctuate in response to steering of the steering wheel such as fast-slow-fast. In addition, for example, when the steering handle starts to rotate rapidly and at a large steering speed, the steering reaction force increases only at the beginning and the steering of the steering wheel becomes caught (clogged), thereby driving the transmission ratio variable motor. Therefore, it does not occur by adjusting the flowing current.

  In addition, when switching from the transmission ratio adjustment mode to the steering torque adjustment mode, the current value to the transmission ratio variable motor is controlled so as to continuously change from the current value in the transmission ratio adjustment mode. There is no sudden change in power and the driver does not feel uncomfortable.

  In addition to the configuration of the invention described in claim 1, the invention described in claim 2 further includes steering operation state information acquisition means for acquiring steering operation state information indicating an operation state of the steering wheel, and switching means. Sets the correction coefficient based on the acquired steering operation state information and the continuous function using the steering operation state information as a variable when switching from the transmission ratio adjustment mode to the steering torque adjustment mode. The second target current value obtained by multiplying the first target current value in this case by a set correction coefficient is used as the current value to the transmission ratio variable motor.

  According to the second aspect of the present invention, the correction coefficient is set based on the acquired steering operation state information, the continuous function using the steering operation state information as a variable, and the first in the case of the steering torque adjustment mode. Since the second target current value obtained by multiplying the target current value by the set correction coefficient is used as the current value to the transmission ratio variable motor, the current value to the transmission ratio variable motor at the time of mode switching is There is no sudden change, a sudden change in steering reaction force does not occur when switching, and the driver does not feel uncomfortable.

  The steering operation state information in the invention described in claim 2 includes the steering speed of the steering wheel (corresponding to claim 3), the steering torque value (corresponding to claim 4), and the generation of auxiliary force used in electric power steering. It is preferably one of the command current values to the assist motor as a source (corresponding to claim 5).

  In the setting of the correction coefficient, a continuous function using the steering operation state information as a variable is used. For example, the steering reaction force increases as the steering speed increases. Steering from the transmission ratio adjustment mode by continuously setting the correction coefficient to be smaller as the value is larger, or continuously setting the correction coefficient to be smaller as the command current value to the assist motor is larger. The current value to the transmission ratio variable motor before and after switching to the torque adjustment mode can be controlled continuously without jumping, so there is no sudden change in the steering reaction force when switching, and the driver does not feel uncomfortable. .

  According to a sixth aspect of the present invention, there is provided a steering apparatus that changes a steering angle transmission ratio of a steering wheel with respect to a turning angle of a steered wheel by a variable transmission ratio mechanism, and generates an assisting force during steering by electric power steering. The transmission ratio adjustment mode for setting the rotation angle of the variable transmission ratio motor used in the variable transmission ratio mechanism and the steering force of the steering wheel are reduced so that the transmission ratio is set to the target transmission ratio according to the vehicle speed. And a switching means for switching between the steering torque adjustment mode for reducing the current for driving the transmission ratio variable motor, and when the steering of the steering wheel is stopped or the steering direction is switched, The current of the transmission ratio variable motor is controlled so that the turning angle does not increase in the steering direction.

  According to the sixth aspect of the present invention, the actual transmission ratio is quickly increased with respect to the target transmission ratio by turning the steering wheel at a high steering speed and by the output torque of the transmission ratio variable motor used in the variable transmission ratio mechanism. Even when it is impossible to follow, when the driver finishes the steering operation of the steering wheel, or when the steering direction is switched, the turning of the steered wheels in the previous steering direction is not continued, so the driver feels uncomfortable. Don't give.

  According to a seventh aspect of the present invention, there is provided a steering apparatus that changes a transmission ratio of a steering angle of a steering wheel with respect to a turning angle of a steered wheel by a variable transmission ratio mechanism, and generates an assisting force during steering by electric power steering. The transmission ratio adjustment setting unit for setting the rotation angle of the transmission ratio variable motor used in the variable transmission ratio mechanism and the steering force of the steering wheel are reduced so that the transmission ratio is set to the target transmission ratio corresponding to the vehicle speed. As described above, the steering torque adjustment setting unit for reducing the current for driving the transmission ratio variable motor is provided, and the control amount output from the steering torque adjustment setting unit is continuously changed.

  According to the seventh aspect of the present invention, the steering torque adjustment setting unit controls the current value to the transmission ratio variable motor so as to continuously change, so that a sudden change in the steering reaction force does not occur, and the driver Does not give a sense of incongruity.

  According to the present invention, it is possible to provide a steering device that can perform comfortable steering even when the driver turns the steering wheel at a high steering speed when the quick ratio is achieved in a low vehicle speed range.

<< First Embodiment >>
Next, a steering apparatus according to a first embodiment of the present invention will be described with reference to FIGS.
(Steering device)
First, the overall configuration of the steering apparatus will be described with reference to FIG. 3 as appropriate with reference to FIG. FIG. 2 is a functional block diagram of the variable transmission ratio mechanism control ECU, and FIG. 3 is a diagram showing a target transmission ratio value set in accordance with the vehicle speed.
FIG. 1 is a schematic configuration diagram of a steering apparatus according to the first embodiment.
As shown in FIG. 1, the steering device 1 includes a steering handle 2, a rack and pinion mechanism 3, an electric power steering device (electric power steering) 4, and a variable transmission ratio mechanism 5.

The electric power steering device 4 includes a torque sensor 21 that detects a steering torque applied to the rotation shaft of the steering handle 2, and an EPS motor 23 (assist) that drives a rack that changes the turning angle of the steered wheels and serves as a source of auxiliary force. Motor) and an EPS ECU 25 that controls the driving of the EPS motor 23.
The variable transmission ratio mechanism 5 includes a planetary gear mechanism 31 serving as a differential gear connected to the rotation shaft of the steering handle 2 and the rack and pinion mechanism 3, and a steering angle of the steering handle 2 with respect to the turning angle of the steered wheels (hereinafter referred to as the steering gear 2). , Referred to as steering wheel angle), a transmission ratio variable motor 33 for rotating the ring gear of the planetary gear mechanism 31 to change the transmission ratio, and a variable transmission ratio mechanism control ECU 9 for driving and controlling the transmission ratio variable motor 33. have.
As will be described later, the variable transmission ratio mechanism control ECU 9A (see FIG. 2) in the first embodiment and the variable transmission ratio mechanism control ECU 9C (see FIG. 10) in the second embodiment are used separately. Typically, the variable transmission ratio mechanism control ECU 9 is displayed.

Torque sensor 21 is provided between the steering wheel 2 and the planetary gear mechanism 31 detects the steering torque applied to the steering wheel 2 and inputs a steering torque value T _h to the EPS ECU 25. Steering torque value T _h, which is measured by the torque sensor 21 is also input to the variable transfer ratio mechanism controlling ECU9A, specifically, the communication line 10 connecting between the variable transfer ratio mechanism controlling ECU9A and EPS ECU 25 To the variable transmission ratio mechanism control ECU 9A.
Steering torque value T _h is the determination of the direction and magnitude of the auxiliary force EPS ECU 25, specifically, be used to determine the EPS for instruction current (not shown) for driving the EPS motor 23 included in the EPS ECU 25 The drive circuit generates an EPS instruction duty based on the EPS instruction current, and drives the EPS motor 23 by PWM (Pulse Width Modulation).
Steering torque value T _h is the variable transfer ratio mechanism controlling ECU9A, it is used to switch from below to the transmission ratio adjustment mode to the steering torque adjustment mode.

The sun gear of the planetary gear mechanism 31 of the variable transmission ratio mechanism 5 is connected to the rotating shaft of the steering handle 2, the carrier is connected to the pinion shaft, and the outer side of the ring gear is fixed to the rotor shaft of the transmission ratio variable motor 33. The external gear which meshes with the made gear is provided.
The transmission ratio variable motor 33 is provided with a motor angle sensor 35 for detecting the rotation angle (hereinafter referred to as “actual motor angle”) θ _vm of the rotor shaft, and the signal is sent to the variable transmission ratio mechanism control ECU 9A. Entered.

Also, if the variable transfer ratio mechanism controlling ECU9A sets the ratio of the turning angle of the steering wheel angle of the steering wheel 2 (steering angle) theta _h steered wheels (transfer ratio) G, in the present embodiment, the turning angle The pinion angle θ _P that is the rotation angle of the pinion shaft that uniquely corresponds to the steering angle is used instead of the turning angle. Therefore, a gear box (not shown) that houses the rack and pinion mechanism 3 is provided with a pinion angle sensor 7 for detecting the pinion angle θ _P , and the signal is input to the variable transmission ratio mechanism control ECU 9A.
Further, the vehicle speed VS acquired by a vehicle speed sensor (not shown) is input to the variable transmission ratio mechanism control ECU 9A via the communication line 10, for example.

Then, the variable transfer ratio mechanism controlling ECU9A, if the vehicle speed VS is low vehicle speed range as shown in FIG. 3, reducing the target transfer ratio G _T (Quick Ratio of) setting, and the vehicle speed VS is in the high vehicle speed range if the target transfer ratio G _T increases (throw ratio of) sets the target current value for controlling the current flowing through the transfer ratio variable motor 33 to match the transmission ratio to the target transfer ratio G _T I have control.

The steering handle 2 is connected to the variable transmission ratio mechanism 5, and the rotation of the pinion shaft output from the variable transmission ratio mechanism 5 is connected to the rotation assistance of the pinion shaft by the electric power steering device 4. The pinion angle θ _P can be increased or decreased by superimposing the actual motor angle θ _vm of the transmission ratio variable motor 33 on θ _h . The relationship of the following equation is established among the pinion angle θ _P , the steering wheel angle θ _h , and the actual motor angle θ _{vm due} to the mechanical constraint relationship.

θ _P = α · θ _h + β · θ _vm (1)
Here, α and β are constants.
And since the transmission ratio G is defined by the following equation,
G = θ _h / θ _P (2)
From the target transmission ratio G _T and the steering wheel angle θ _{h at} that time, the target pinion angle θ _TP is expressed by the following equation.
θ _TP = (1 / G _T ) θ _h (3)
Substituting θ _TP in equation (3) instead of θ _P in equation (1), the target motor angle θ _Tvm of the transmission ratio variable motor 33 is obtained as follows.
θ _Tvm = (1 / β) · {(1 / G _T ) −α} θ _h (4)

(Variable transmission ratio mechanism control ECU)
Next, a detailed functional configuration of the variable transmission ratio mechanism control ECU will be described with reference to FIGS. FIG. 4 is a diagram showing correction coefficient values set according to the absolute value of the steering wheel angular velocity.

As shown in FIG. 2, the variable transmission ratio mechanism control ECU 9A feeds power from the battery power source to the transmission ratio variable motor 33 under the control of the CPU 9a, memories such as ROM and RAM (not shown), input / output circuits (not shown), and CPU 9a. The motor drive circuit 17 is included. The motor drive circuit 17 is provided with a current sensor 18 that detects an actual current value supplied to the transmission ratio variable motor 33.
The ROM described above stores a variable transmission ratio control program and data, and each function of the functional configuration block shown in FIG. 2 is realized by the CPU 9a executing the program.
Incidentally, with respect to the steering wheel angle theta _h input to the CPU 9a, but are not shown in the functional block diagram shown in FIG. 2, the steering wheel angle theta _h time differentiation on the steering wheel angular velocity (steering speed) A steering wheel angular velocity calculation unit (not shown) that calculates ω _h every moment and inputs the correction coefficient setting unit 20 to be described later is provided.

  The variable transmission ratio mechanism control ECU 9A controls the transmission ratio variable motor 33 by switching between two modes, a transmission ratio adjustment mode and a steering torque adjustment mode. First, the transmission ratio adjustment mode will be described, and then the steering torque adjustment mode will be described.

(Transmission ratio adjustment mode)
The transmission ratio adjustment mode will be described. First, the target transfer ratio setting section 11, a target transfer ratio G _T corresponding to the vehicle speed VS of the vehicle is set, it is outputted to the target motor angle setting section 12A. If the vehicle speed VS is low vehicle speed range, to set a small target transfer ratio G _T, as shown in FIG. 3 (quick ratio of) the vehicle speed VS is if high vehicle speed range, increasing the target transfer ratio G _T (Slow Set the ratio).

Next, the target motor angle setting section 12A, to achieve the target transfer ratio G _T input, based on the equation (4) to the target motor angle theta _Tvm and said transfer ratio variable motor 33, the current steering calculates and sets from the steering wheel angle θ _h.

The subtraction unit 13 subtracts the actual motor angle θ _vm output from the motor angle sensor 35 from the target motor angle θ _Tvm , and the subtraction result is a position feedback control unit 14 (hereinafter referred to as a position F / B control unit 14). To enter. In position F / B control section 14, so that the subtraction result becomes zero, i.e., as the target motor angle theta _Tvm the actual motor angle theta _vm match, the transmission ratio G to the target transfer ratio G _T in other words The target current value (first target current value) I _T1 is adjusted so as to match, and is output to the multiplier 19.
Here, the target current value I _T1 is provided with a limit value that defines the upper limit of the absolute value.

In the transmission unit adjustment mode, the multiplication unit 19 uses the correction coefficient K ₁ = 1.0 input from the correction coefficient setting unit 20 and uses the value of the target current value I _T1 as the current value to the transmission ratio variable motor 33. Is directly output to the subtraction unit 15 as the target current value (second target current value) I _T2 .
Detailed functions of the correction coefficient setting unit 20 will be described in a torque adjustment mode described later.

The subtraction unit 15, the target current value (second target current value) I _T2, and subtracts the actual current value I _m of the transfer ratio variable motor 33 detected by the current sensor 18, current feedback control of the subtraction result To the unit 16 (hereinafter referred to as the current F / B control unit 16). The current F / B control unit 16 outputs a variable transmission ratio indicating current to the motor drive circuit 17 so that the subtraction result becomes zero, that is, the actual current value _Im matches the target current value _IT2. Is output to the motor drive circuit 17.

By supplying a drive current from the motor drive circuit 17 to the transmission ratio variable motor 33, the transmission ratio variable motor 33 rotates and the actual motor angle θ _vm changes. The actual motor angle θ _vm detected by the motor angle sensor 35 is output to the subtraction unit 13.
Thus, in the transmission ratio adjustment mode, the feedback of the actual motor angle theta _vm and the feedback of the actual current value I _m is performed, it is possible to the actual motor angle theta _vm coincides with the target motor angle theta _Tvm, in other words, it is possible to match the transmission ratio G to the target transfer ratio G _T.

(Torque adjustment mode)
Next, the steering torque adjustment mode will be described with reference to FIGS. 1, 2, and 4 as appropriate with reference to the flowchart of FIG. FIG. 5 is a flowchart showing the flow of switching control between the transmission ratio adjustment mode and the torque adjustment mode in the correction coefficient setting unit and the setting control of the second target current value in the torque adjustment mode.
In the steering torque adjustment mode, the correction coefficient setting unit 20 sets a correction coefficient K ₁ so as to reduce the steering force of the steering wheel 2 (see FIG. 1), and outputs the correction coefficient K ₁ to the multiplication unit 19 to transmit the transmission ratio variable instruction. The other points are the same as those in the transmission ratio adjustment mode except that the current is adjusted. The description overlapping with the transmission ratio adjustment mode is omitted.

First, the function of the correction coefficient setting unit 20 will be described in detail. As shown in FIG. 2, the correction coefficient setting unit 20 receives the steering torque value T _h from the torque sensor 21, the vehicle speed VS from the vehicle speed sensor (not shown), and the steering wheel angular velocity ω _h . The correction coefficient setting unit 20, based on the steering torque value T _h, calculates the mode switching determination value to be described later, when the calculated mode switching determination value is not smaller than a predetermined threshold value, the steering torque from the transmission ratio adjustment mode By switching to the adjustment mode and referring to the data of the continuous function (see FIG. 4) corresponding to the vehicle speed VS stored in the ROM in the steering torque adjustment mode, the correction coefficient K ₁ for the absolute value | ω _h | Set.

The continuous function for determining the correction coefficient K ₁ having the absolute value | ω _h | of the steering wheel angular velocity (steering operation state information) shown in FIG. 4 as the variable is the absolute value | ω _h | _Up to ω _hth , the correction coefficient K ₁ = + 1.0 is shown, and when the predetermined threshold value ω _hth is exceeded, the correction coefficient K ₁ decreases, and when it reaches −1.0, the characteristic is saturated at −1.0. Yes.
By allowing a negative value to a correction factor K _1, the target current value I _T2 results correction coefficient K ₁ to the target current value I _T1 is multiplied by the multiplication unit 19 is reversed to the direction of the target current value I _T1 Is allowed. That is, the target motor angle θ _Tvm of the transmission ratio variable motor 33 in the quick ratio direction is allowed to be changed to the target motor angle θ _Tvm of the transmission ratio variable motor 33 in the slow ratio direction, and the steering reaction force is reduced. Let

Here, the threshold value ω _hth changes according to the vehicle speed VS. The smaller the vehicle speed VS, the smaller the threshold value ω _hth is set, and the larger the vehicle speed VS, the larger the threshold value ω _hth is set.
This target transfer ratio G _T set by the target transfer ratio setting section 11, as the vehicle speed VS is less reduced target transfer ratio G _T, that is, since the set quick ratio side, the stronger the degree of the quick ratio This is because even if the absolute value | ω _h | of the steering wheel angular velocity is small, the EPS motor 23 of the electric power steering device 4 tends not to follow.
Note that the slope of the correction coefficient K _{1 in} the region where the absolute value | ω _h | of the steering wheel angular velocity exceeds the predetermined threshold value ω _hth may also be changed according to the vehicle speed VS.

Next, the flow of control for setting the correction coefficient K ₁ in the correction coefficient setting unit 20 and outputting the target current value I _T2 in the multiplication unit 19 will be described with reference to FIG. 5 as appropriate.
Steps S01 to S13 in the flowchart described below are processed in the correction coefficient setting unit 20, and steps S14 and S15 are processed in the multiplication unit 19. Incidentally, step S16 is performed in the overall control in the CPU 9a.
When the ignition switch (IG) is turned on, the variable transmission ratio mechanism control ECU 9A is activated. When the variable transmission ratio mechanism control program is started in the CPU 9a (see FIG. 2), the state of the transmission ratio adjustment mode is set as an initial setting. The flag indicating whether (IFLAG = 0) or the state of torque adjustment mode (IFLAG = 1) is reset to be a transmission ratio adjustment mode flag (step S01, IFLAG = 0). Thereafter, steps S02 to S16 are repeatedly performed at a constant cycle.
In step S02, the vehicle speed VS, the steering angular velocity ω _h , the steering torque value T _h , and the target current value I _T1 output from the position F / B control unit 14 are read.

In step S03, it calculates the mode switching determination value T ^* based on the steering torque value T _h. For example, without directly using the absolute value of the steering torque value T _h as the mode switching determination value T ^*, using the absolute value of the steering torque value T _h obtained by adding the time obtained by differentiating the steering torque differential value thereto. Although the sum of the steering torque differential value of the steering torque value T _h by the absolute value and the mode switching determination value T ^*, in accordance with the steering operation of the driver, the transmission ratio adjustment mode of the transmission ratio variable indicator current The timing for switching to the torque adjustment mode can be finely adjusted.
In other words, the rapid steering operation of the steering wheel 2, early in than the absolute value is reached to the mode switching determination value T ^* threshold X _T and sharp rise in the steering torque value T _h, to detect a rapid steering operation The torque adjustment mode can be switched.
This is because, even when the vehicle speed VS is in a low value state and the same steering angular speed ω _h is assumed, the road surface state is dry, wet, paved road surface, or unpaved ground surface. Switch from transmission ratio adjustment mode to torque adjustment mode early so that the force required when the steered wheels are steered differs depending on the conditions, etc., and the auxiliary force of EPS motor 23 can be flexibly dealt with This is to make it happen.
By doing so, it is possible to avoid the steering steering reaction force from becoming suddenly heavy at an early stage.

In step S04, the calculated mode switching determination value T ^* is checked whether or larger than the threshold X _T at step S03. Mode switching when the determination value T ^* is not less than the threshold X _T (Yes), the process proceeds to step S06, if ^* the mode switching determination value T of less than the threshold X _T (No), the process proceeds to step S05.
At first, the absolute value of the steering torque value _Th and the steering torque differential value is absolute because the driver does not perform the steering operation of the steering wheel 2 or the absolute value of the steering angular velocity ω _h is small even if the steering operation is performed. value (the mode switching determination value) T ^* is less than the threshold X _T, the process proceeds to step S05.

In step S05, it is checked whether IFLAG = 1. If IFLAG = 1 (Yes), the process proceeds to step S11. If IFLAG # ≠ 1 (No), the process proceeds to step S13. Here, since IFLAG_0 in step S01, the process proceeds to step S13, the correction coefficient K1 is set to 1.0, and the process proceeds to step S14.
In step S14, I _T2 = K ₁ × I _T1 is set, and I _T2 is output as a target current value to the subtraction unit 15 (see FIG. 2) (step S15). Then, the process proceeds to step S16, where it is checked whether the ignition switch is turned off (IG OFF?). Returning to step S02, steps S02 to S16 are repeated.

If the result of step S04 is Yes and the process proceeds to step S06, IFLAG = 1 is set, a flag indicating the state of the torque adjustment mode is set, and correction coefficient data corresponding to the vehicle speed VS read in step S02 is referred to (step S07). Specifically, for example, several types of continuous functions having the absolute value | ω _h | of the steering angular velocity for determining the correction coefficient K ₁ as shown in FIG. 4 for different values of the predetermined vehicle speed VS are prepared. Then, a desired continuous function is obtained by interpolating according to the value of the vehicle speed VS read in step S02.

In step S08, it is checked whether or not the absolute value | ω _h | of the steering wheel angular velocity is equal to or _greater than a threshold value ω _hth . If it is greater than or equal to the threshold value ω _hth (Yes), the process proceeds to step S10, and if it is less than the threshold value ω _hth (No), the process proceeds to step S09.
In this case, assuming that the threshold value ω _hth has not yet been reached, the process proceeds to step S09, the correction coefficient K1 is set to 1.0, and the process proceeds to step S14. Thereafter, as described above, the process proceeds to steps S14 to S16, returns to step S02, and repeats steps S02 to S16.

In step S08 in Yes, if the process proceeds to step S10, referred to in step S08, in particular the desired continuous function determining the correction factor K ₁ obtained by interpolating according to the value of the vehicle speed VS _First , the correction coefficient K ₁ corresponding to the absolute value | ω _h | of the steering wheel angular velocity read in step S02 is set. And it progresses to step S14-S16, returns to step S02, and repeats step S02-S16.

In the course of repeating a series of steps S02 to S16 after the IFLAG_ = 1 state, the answer is No in Step S04 and if the process proceeds to Step S05, the answer is Yes in Step S05 and the process proceeds to Step S11.
In step S11, whether the absolute value (| previous I _T2 −I _T1 |) of the difference between the previous target current value I _T2 in this series of iterations and the target current value I _T1 read in this step S02 is less than or equal to the threshold ε. Check whether or not.
When the threshold value ε is exceeded (No), it means that it is determined that the torque adjustment mode is continued, and the process proceeds to step S07, and steps S07 to S16 are repeated.
If it is equal to or less than the threshold value ε (Yes), it means that it is determined that the torque adjustment mode has ended, the process proceeds to step S12, and IFLAG_ = 0 (transmission ratio adjustment mode), the process proceeds to step S13. It progresses to S16, returns to step S02, and repeats steps S02-S16.
Incidentally, the threshold value ε is a value that does not make the driver feel a jump of the steering torque reaction force.

The description of the series of control flow for setting the correction coefficient K ₁ in the correction coefficient setting unit 20 and outputting the target current value I _T2 in the multiplication unit 19 is finished.
Here, step S02 of the flowchart of the present embodiment corresponds to the steering operation state information acquisition unit described in the claims, and steps S03 to S05, S011 correspond to the switching unit described in the claims.

Next, the effect of the control by the variable transmission ratio mechanism control ECU 9A in this embodiment is the case with the variable transmission ratio mechanism control ECU 9B of the comparative example that does not have the correction coefficient setting unit 20 and the multiplication unit 19 as shown in FIG. Comparison will be described.
(A) of FIG. 7 is a figure which shows the time transition of steering steering wheel angular velocity (omega) _h , (b) is a figure which shows the time transition of the value of target current value _IT1 and target current value _IT2 , c) is a diagram illustrating the evolution in time of the steering torque value T _h.

In (a) of FIG. 7, the steering wheel angular velocity omega _h increases in the positive direction at time t _1A, the mode switching determination value T ^*, exceeds the threshold X _T, the subsequently time t _1B, a steering wheel _Assuming that the absolute value of the angular velocity | ω _h | exceeds the threshold value ω _hth , the target current value I _T2 has been the same value as the target current value I _T1 in the present embodiment as shown in FIG. Thereafter, when the absolute value of the steering wheel angular velocity ω _h becomes _{equal to} or greater than the threshold value ω _hth , the target current value I _T2 starts to decrease from the target current value I _T1 . In this example, the absolute value of the steering wheel angular velocity ω _h becomes _{equal to} or greater than the threshold ω _hth at a time t _1B that is not long after the time t _1A has elapsed, and the correction coefficient K is a value corresponding to the absolute value | ω _h | It can be seen that ₁ is less than 1.0. Thereafter, the driver continues further steering operation to increase the steering wheel angular velocity ω _h , and the target current value I _T2 rapidly decreases accordingly. Finally, the target motor angle θ _Tvm is reduced to what has been so far. The target current value I _T2 is negative with the reverse direction (slow ratio direction).
Thereafter, the correction coefficient K ₁ gradually approaches 1.0 in response to the decrease in the steering wheel angular velocity ω _h with a positive value. That is, the target current value I _T1 and the target current value I _T2 approach each other. At time t ₂ when the absolute value of the difference becomes equal to or less than the threshold value ε, the torque adjustment mode is switched to the transmission ratio adjustment mode. Thereafter, the target current value I _T2 returns to the same value as the target current value I _T1 .

As a result, in the comparative example, the target current value I _T1 in FIG. 7B is input to the subtracting unit 15, and the current F / B control unit 16 generates the transmission ratio variable instruction current. steering torque values as shown in dashed c) T _h (steering while the time course of the reaction force), steering torque value T _h of gentle change as shown by the solid line in the case of this embodiment (the steering reaction Force) over time, the steering wheel angular velocity absolute value | ω _h | increases and the steering reaction force suddenly increases when the assist force of the EPS motor 23 (see FIG. 1) cannot follow, It is not necessary to give the driver an uncomfortable feeling such as a phenomenon that the steering reaction force fluctuates in response to a steering operation such as fast-slow-fast. Even when returning from the torque adjustment mode state to the transmission ratio adjustment mode state, since the absolute value of the difference between the target current value I _T1 and the target current value I _T2 is reduced, the steering reaction force is reduced. Don't feel jumping.

  In summary, according to the present embodiment, when the quick ratio is set, when the driver steers the steering wheel 2 quickly, the command current value given to the transmission ratio variable motor 33 is the quick ratio. Can be switched from the command current value to achieve the steering reaction force to reduce the steering reaction force, and when the driver returns to a slow steering operation, the quick ratio It is possible to return to the indicated current value for achieving the above.

  In addition, after switching to the control of the command current value in the torque adjustment mode, when the normal steering operation that is not the sudden steering of the steering wheel 2 is performed, the control returns to the control state of the command current value for achieving the quick ratio. Thus, a turning angle close to the movement of the steered wheels intended by the driver is realized.

Further, in the technique described in Patent Document 1 described above, the target transfer ratio G _T set according to the vehicle speed VS in the target transfer ratio setting section 11, thereafter, the absolute value of the steering wheel angular velocity | omega _h | or steering T _h | | absolute value of the torque values calculated correction coefficient according to a method of obtaining a target transfer ratio G _T is multiplied by the obtained correction coefficient. Then it calculates a target motor angle theta _Tvm from the modified target transfer ratio G _T, and controls the actual motor angle _vm and target motor angle and generates a control signal to the deviation between theta _Tvm transfer ratio variable motor 33 Is.

Originally, if the steering reaction force is limited to the action of the variable transmission ratio mechanism 5, the control signal generated for the deviation between the actual motor angle θ _vm and the target motor angle θ _Tvm (in this embodiment, the target current value I a than changes Kakari' _T1, I _T2) directly, because the target transfer ratio G _T, such that according to the indirect, towards the present embodiment is effective in the control of direct steering reaction force. Therefore, in order to directly suppress the sudden increase in the steering reaction force at the time of the quick ratio, the present embodiment has better response characteristics than the technique described in Patent Document 1.

<< Modification of First Embodiment >>
Next, a modification of the first embodiment will be described with reference to FIGS.
In the first embodiment, the mode switching control is performed using the mode switching determination value T ^* , but the present invention is not limited to this.
In this modification, for example, those with using the steering torque value T _h is a steering operation state information to switch the parameters of the transmission ratio adjustment mode and the torque adjustment mode, also used as a variable of continuous function determining the correction factor K ₁ It is. The flow of control for setting the correction coefficient K ₁ in the correction coefficient setting unit 20 and outputting the target current value I _T2 in the multiplication unit 19 will be described below.
In the present embodiment, a function having the steering wheel angular velocity ω _h as a variable is used as a continuous function for calculating the correction coefficient K ₁ , but the present invention is not limited to this. In a modification of the present embodiment to be described later, a continuous function having a steering torque value _Th as a variable as shown in FIG. 9 may be used, or an instruction current or an instruction current generated by the EPS ECU 25 of the EPS motor 23 may be used. A generated DUTY signal may be used.

FIG. 8 is a flowchart showing the flow of the switching control between the transmission ratio adjustment mode and the torque adjustment mode in the correction coefficient setting unit in the present modification and the setting control of the second target current value in the torque adjustment mode. 9 is a diagram showing the value of the correction coefficient set according to the absolute value of the steering torque value.
Steps S111 to S115 in the flowchart described below are processed in the correction coefficient setting unit 20, and steps S116 and S117 are processed in the multiplication unit 19. Incidentally, step S118 is performed in the overall control in the CPU 9a.
When the ignition switch (IG) is turned on, the variable transmission ratio mechanism control ECU 9A is activated, and when the variable transmission ratio mechanism control program is started in the CPU 9a (see FIG. 2), steps S111 to S118 are performed at regular intervals. Repeat processing.

In step S111, the vehicle speed VS and the steering torque value _Th are read.
In step S112, the correction coefficient data corresponding to the vehicle speed VS read in step S111 is referred to. Specifically, for example, the absolute value of the steering torque value to determine the correction factor K ₁ shown in FIG. 9 | T _h | a continuous function whose variable is, several for different values of the predetermined vehicle speed VS A desired continuous function is obtained by interpolating according to the value of the vehicle speed VS prepared and read in step S111.

Steering torque value shown in FIG. 9 the absolute value of (a steering operation state information) | T _h | a continuous function determining the correction factor K ₁ whose variable is the absolute value of the steering torque value | T _h | a predetermined threshold value from 0 _Up to T _hth , the correction coefficient K ₁ = + 1.0 is shown. When the predetermined threshold value _{Th hth} is exceeded, the correction coefficient K ₁ decreases, and when it reaches −1.0, it shows a characteristic of being saturated at −1.0.
By allowing a negative value to a correction factor K _1, the target current value I _T2 results correction coefficient K ₁ to the target current value I _T1 is multiplied by the multiplication unit 19 is reversed to the direction of the target current value I _T1 Is allowed. That is, the target motor angle θ _Tvm of the transmission ratio variable motor 33 in the quick ratio direction is allowed to be changed to the target motor angle θ _Tvm of the transmission ratio variable motor 33 in the slow ratio direction, and the steering reaction force is reduced. Let

Here, the threshold value T _hth changes according to the vehicle speed VS, the value of the threshold T _hth as the vehicle speed VS is small is set larger, the value of the threshold T _hth as the vehicle speed VS is high is set to be smaller.
This target transfer ratio G _T set by the target transfer ratio setting section 11, as the vehicle speed VS is less reduced target transfer ratio G _T, that is, since the set quick ratio side, the stronger the degree of the quick ratio This is because the absolute value | T _h | (steering reaction force) of the steering torque value increases, and this tendency is easily perceived by the driver.
Note that the slope of the correction coefficient K _{1 in} the region where the absolute value | ω _h | of the steering torque value exceeds the predetermined threshold ω _hth may also be changed according to the vehicle speed VS.

In step S113, it is checked whether the absolute value | T _h | of the steering torque value is equal to or _greater than a threshold value _{Th hth} . If it is _{equal to} or greater than the threshold value _Thhth (Yes), the process proceeds to step S115, and if it is less than the threshold value _Thhth (No), the process proceeds to step S114.
In step S114, the correction coefficient K1 is set to 1.0, and the process proceeds to step S116. In step S116, I _T2 = K ₁ × I _T1 is set, and I _T2 is output as a target current value to the subtracting unit 15 (see FIG. 2) (step S117). Then, the process proceeds to step S118, where it is checked whether the ignition switch is turned off (IG OFF?). Returning to step S111, steps S111 to S118 are repeated.

In step S113 in Yes, if the process proceeds to step S115, in particular based on the desired continuous function determining the correction factor K ₁ obtained by interpolating according to the value of the vehicle speed VS referred to in step S112 Thus, the correction coefficient K ₁ corresponding to the absolute value | T _h | of the steering torque value read in step S111 is set. And it progresses to step S116-S118, returns to step S111, and repeats step S111-S118.

  Here, step S111 in the flowchart of this modification corresponds to the steering operation state information acquisition unit recited in the claims, and step S113 corresponds to the switching unit recited in the claims.

According to this modification, when the quick ratio is set, if the driver performs the steering faster steering wheel 2, to set the correction factor K ₁ in the torque adjustment mode based on the steering torque value T _h, the target A target current value I _T2 is set by multiplying the current value I _T1 by the correction coefficient K ₁ . Accordingly, the steering torque value T _h (steering reaction force) changes gradually as shown by the solid line in FIG. 7C, the absolute value | T _h | of the steering torque value increases, and the EPS motor The steering reaction force fluctuates in response to a sudden increase in the steering reaction force generated when the auxiliary force 23 (see FIG. 1) cannot follow, or the steering operation of the steering handle 2 such as fast-slow-fast. There is no need to give the driver a sense of discomfort such as a phenomenon.
Further, since the steering torque value _Th is used for both the switching between the transmission ratio adjustment mode and the torque adjustment mode and the setting of the correction coefficient K ₁ to a value less than 1.0, the transmission ratio adjustment mode and the torque adjustment mode are used. Switching between and can be done smoothly. Even when the transmission ratio adjustment mode is switched to the torque adjustment mode, the correction coefficient K ₁ continuously changes, so that the steering handle 2 is suddenly operated in the quick ratio state without causing a sudden change in the steering reaction force. The sudden increase of the steering reaction force due to can be suppressed.

The steering operation state information in the present modified example, not intended to be limited to the steering torque value T _h, substantially the same change in behavior between the steering torque value T _h, instruction about to be generated by the EPS ECU 25 of the EPS motor 23 A DUTY signal generated by the current or the instruction current may be used.

In addition, the steering wheel angular velocity ω _h may be used as a parameter used for switching between the transmission ratio adjustment mode and the torque adjustment mode in the present modification and the above-described steering operation state information. In this case, the continuous function using the absolute value | ω _h | of the steering wheel angular velocity used as a variable for determining the correction coefficient K ₁ has been described with reference to FIG. 4 in the first embodiment. The threshold value ω _hth setting method for setting the continuous function correction coefficient K ₁ from a value of 1.0 in the transmission ratio adjustment mode to a value less than 1.0 in the torque adjustment mode is also the same as that of the first embodiment. The same.

<< Second Embodiment >>
Next, a steering apparatus according to a second embodiment of the present invention will be described with reference to FIGS.
FIG. 10 is a functional block diagram of the variable transmission ratio mechanism control ECU in the steering device according to the present embodiment, FIG. 11 is a detailed functional block diagram of the target motor angle setting unit, and FIG. 12 is a target motor angle setting. It is a flowchart which shows the flow of control which correct | amends the target pinion angle in a part.
FIG. 13A is a diagram showing a time transition of the actual motor angle θ _vm and the target motor angle θ _Tvm of the transmission ratio varying motor in the comparative example, and FIG. 13B is a diagram for varying the transmission ratio in the second embodiment. It is a figure which shows the time transition of real motor angle (theta) _vm of a motor, and target motor angle (theta) _Tvm .

The steering device 1 in the second embodiment is different from the first embodiment or the modification thereof in that the target motor angle setting unit 12A in the variable transmission ratio mechanism control ECU 9A in the first embodiment is the target motor angle setting unit 12B. It is a point that changes to. Others are the same as those of the first embodiment or its modification.
The same components as those in the first embodiment or the second embodiment are denoted by the same reference numerals, and redundant description is omitted.

As shown in FIG. 11, the target motor angle setting unit 12B includes a target pinion angle calculation unit 12a, a target motor angle calculation unit 12b, a target pinion angle correction amount calculation unit 12c, and an addition unit 12d. Target pinion angle calculating section 12a, using the target transfer ratio G _T set according to the vehicle speed VS in the target transfer ratio setting section 11 calculates the target pinion angle theta _TP based on the equation (3). Calculated target pinion angle theta _TP is input to the target pinion angle correction amount calculating section 12c addition unit 12d.

The target pinion angle correction amount calculation unit 12c determines whether the steering operation of the steering handle 2 by the driver is in the “handle increase”, “handle return”, or “handle stop” state,
(1) When the same as the previous steering operation state, the previous target pinion angle correction amount Δθ _c1 is set as the current target pinion angle correction amount Δθ _c2 and input to the adder 12d.
(2) When there is a change from the previous steering operation state and the current steering operation state is “steering wheel increase”, the current target pinion angle correction amount Δθ _c2 = 0.0 is input to the adding unit 12d. To do.
(3) When there is a change from the previous steering operation state and the current steering operation state is “steering wheel turning back” or “steering wheel stop or steering wheel neutral”, the actual pinion angle θ _P and the target pinion angle θ at that time the difference between _TP and (θ _P -θ _TP) is calculated as the current target pinion angle correction amount [Delta] [theta] _c2, is inputted to the addition unit 12d.
Details will be described later in the description of the flowchart of FIG.

Addition unit 12d adds the target pinion angle calculating section 12a target pinion angle correction amount inputted from the target pinion angle theta _TP and the target pinion angle correction amount calculating section 12c which is input from the [Delta] [theta] _c2, the corrected target The pinion angle θ _CTP is input to the target motor angle calculation unit 12b.
Target motor angle calculating section 12b is input to the corrected target pinion angle theta _CTP, in formula (1), by substituting theta _CTP instead of theta _P, the target motor angle theta _Tvm as: calculate.
θ _Tvm = (θ _P −α · θ _h ) / β (5)
The target motor angle θ _Tvm calculated by the target motor angle calculation unit 12 b is input to the subtraction unit 13.
The subsequent steps are the same as in the first embodiment.

Next, the flow of control for correcting the target pinion angle in the target motor angle setting unit will be described with reference to FIG.
This process is mainly performed by the target pinion angle correction amount calculation unit 12c and the addition unit 12d.
When IG is turned ON, the target motor angle setting unit 12B sets the previous flag indicating the steering operation state as an initial setting to IFLAGA = 0 (“steering wheel stop” state), and sets the previous target pinion angle correction amount Δθ _C1 . 0.0. Thereafter, the processing of the flowchart is performed at a constant cycle. When IG is turned off, the process is stopped.

In step S21, the target pinion angle correction amount calculation unit 12c calculates the steering wheel angle θ _h , the actual pinion angle θ _P , the target pinion angle θ _TP , the steering wheel angular velocity ω _h , the previous flag IFLAGA, and the previous correction amount Δθ _C1 . Read.
In step S22, the target pinion angle correction amount calculation unit 12c calculates a steering operation state determination parameter A ^* (A ^* = θ _h × ω _h ).

In step S23, the target pinion angle correction amount calculation unit 12c checks whether or not the steering operation state determination parameter A ^* is a positive value. If the value is positive (Yes), the process proceeds to step S24, and the target pinion angle correction amount calculation unit 12c sets IFLAG = + 1 (the steering wheel is increased), and the process proceeds to step S28.
When it is not a positive value in Step S23 (No), the process proceeds to Step S25, and the target pinion angle correction amount calculation unit 12c checks whether or not the steering operation state determination parameter A ^* is a negative value.
In step S25, if the steering operation state determination parameter A ^* is a negative value (Yes), the process proceeds to step S26, and the target pinion angle correction amount calculation unit 12c sets IFLAG = -1 (steering back) and proceeds to step S28. .
In step S25, when the steering operation state determination parameter A ^* is not a negative value (No), the process proceeds to step S27, where the target pinion angle correction amount calculation unit 12c sets IFLAG = 0 (steering wheel stop or steering wheel neutral), and then proceeds to step S28. move on.

In step S28, the target pinion angle correction amount calculation unit 12c determines whether or not the previous flag indicating the steering operation state and the current flag indicating the steering operation state set in step S24, S26, or S27 have the same value. Check (IFLAGB = IFLAGA?).
If they are the same (Yes), the process proceeds to step S29, and the target pinion angle correction amount calculation unit 12c sets the correction amount Δθ _C2 to be the same as the previous correction amount Δθ _C1 (Δθ _C2 = Δθ _C1 ).
In step S28, when the previous flag indicating the steering operation state and the current flag IFLAGB indicating the steering operation state set in step S24, S26, or S27 are not the same value (No), the process proceeds to step S32. The pinion angle correction amount calculation unit 12c checks whether or not the flag indicating the current steering operation state is a positive value (IFLAGB> 0?).

When IFLAGB is a positive value in step S32 (Yes), the process proceeds to step S33, and the target pinion angle correction amount calculation unit 12c sets the correction amount Δθ _C2 = 0.0, and then proceeds to step S30.
When IFLAGB is not a positive value in step S32 (No), the process proceeds to step S34, and the target pinion angle correction amount calculation unit 12c sets the correction amount Δθ _C2 = θ _P −θ _TP, and then proceeds to step S30.

In step S30, the adding unit 12d adds the target pinion angle calculation unit step to the target pinion angle theta _TP calculated in 12a S29, S33, or S34 in this set by the correction amount [Delta] [theta] _C2, corrected target The pinion angle θ _{CTP is} assumed (θ _CTP = θ _TP + Δθ _C2 ).
In step S31, the target pinion angle correction amount calculation unit 12c sets the previous correction amount Δθ _C1 used for the next iteration as the current correction amount Δθ _C2 (Δθ _C1 = Δθ _C2 ), and the flag for the current steering operation state. Is used as the flag of the previous steering operation state used for the next iteration (IFLAGA = IFLAGB).
Thus, a series of repeated processing is completed.

Here, first, the operation state of the steering wheel 2 is “steering wheel stop”, IFLAGA = 0, correction amount Δθ _C1 = 0.0. For example, when the steering wheel 2 starts to be turned to the right, in step S28, The previous flag (IFLAGA = 0) and the current flag (IFLAGB = + 1) do not match, and the process proceeds to step S32, and further proceeds to step S33. In step S30, θ _CTP = θ _TP , and in step S31, Δθ _C1 = 0.0, IFLAGA = + 1.
Thereafter, when the state of “rounded up” continues, the process proceeds from step S28 to steps S29 and S30. In step S30, θ _CTP = θ _TP , and in step S31, Δθ _C1 = 0.0 and IFLAGA = + 1. .

When the driver puts the steering operation state into the “switchback” state, the process proceeds from step S28 to steps S32 and S34, where the follow-up of the transmission ratio variable motor 33 is delayed and the actual pinion angle θ _P is set to the target pinion. When the angle θ _TP is behind, Δθ _C2 ≠ 0.0, and the corrected target pinion angle of the transmission ratio variable motor 33 is θ _CTP = θ _TP + Δθ _C2 (correction amount Δθ _C2 = θ _P −θ _TP ) Is set, and the subsequent follow-up operation corresponding to the delay in the follow-up of the transmission ratio variable motor 33 is stopped.
Similarly, even if the steering operation state of the steering handle 2 changes from “addition of the steering wheel” to the “stop of the steering wheel” state, similarly, the subsequent tracking operation corresponding to the delay in the tracking of the transmission ratio variable motor 33 is performed. Stop.
Accordingly, the corrected target pinion angle θ _CTP reflecting the actual pinion angle θ _P is output to the target motor angle calculation unit 12b, and the target motor angle θ _Tvm based on the corrected target pinion angle θ _CTP reflects the actual motor angle θ _vm .

In the state of the quick ratio, the driver's rapid steering handle 2 (see FIG. 1) steers the motor angle θ _vm quickly due to insufficient output torque of the transmission ratio variable motor 33 (see FIG. 1). It becomes impossible to follow the angle θ _Tvm . Therefore, when stopping the operation of the steering wheel 2 at time t ₃ as in the comparative example shown in (a) of FIG. 13, the actual motor angle theta _vm as the case of the conventional follow the target motor angle theta _Tvm Since the control is continued, the turning of the steered wheels continues, and the driver feels uncomfortable through the behavior of the vehicle and the steering reaction force. If you stop the operation of the steering wheel 2 at time t ₃ as shown in (b) of FIG. 13 according to this embodiment, since the target motor angle theta _Tvm is matched to the actual motor angle theta _vm, movement of the steered wheels Will not stop and will not give such a sense of incongruity.

(Modification of the second embodiment)
Next, a modification of the second embodiment will be described with reference to FIGS. In this modification, the control flow of FIG. 12 for correcting the target pinion angle in the target motor angle setting unit 12B in the second embodiment is changed.
14 and 15 are flowcharts showing the flow of control for correcting the target pinion angle in the target motor angle setting unit. 16A is a graph showing the time transition of the steering wheel angle θ _h , FIG. 16B is a graph showing the time transition of the steering wheel angular velocity ω _h , and FIG. 16C shows the steering operation state. FIG. 4D is a graph showing a change in the value of the flag shown, and FIG. 4D is a graph showing a time transition of the correction amount Δθ _C2 .
In this modification, in the flowchart of FIG. 12, (a) the steering operation state is recognized as “handle stop” even when the steering wheel angle θ _h is 0.0 degree, and (b) “ Even in the “turn back” state, the difference correction (Δθ _C2 ) between the target pinion angle θ _TP and the actual pinion angle θ _P is performed. Therefore, the differential correction (Δθ _C2 ) between the target pinion angle θ _TP and the actual pinion angle θ _P is always performed, and the continuous operation of “Right hand wheel increase” → “Handle switch back” → “Right or left handle increase” is performed. followed by case, what was done a certain value of the difference correction between the "steering returning" (Δθ _C2) is, as soon as the transition to the "right or left steering wheel-increasing", the difference correction (Δθ _C2) becomes zero The driver feels uncomfortable with the steering torque reaction It is an improvement of the point that may give.

This control process is mainly performed by the target pinion angle correction amount calculation unit 12c and the addition unit 12d.
When the IG is turned on, the target motor angle setting unit 12B sets the previous flag indicating the steering operation state as 0 as an initial setting to 0 (IFLAGA = 0 (the steering operation state of “steering wheel stop”)), and a flag indicating immediately after the IG is turned on. Is set to 0 (IFLAGC = 0), and the previous target pinion angle correction amount Δθ _{C1 is set} to 0.0 (step S41).

In step S42, the target pinion angle correction amount calculation unit 12c sets the steering wheel angle θ _h , the actual pinion angle θ _P , the target pinion angle θ _TP , the steering wheel angular velocity ω _h , the previous correction amount Δθ _C1 , and the previous flag IFLAGA. Read.
In step S43, the target pinion angle correction amount calculation unit 12c calculates a steering operation state determination parameter A ^* (A ^* = θ _h × ω _h ).

In step S44, the target pinion angle correction amount calculation unit 12c satisfies the condition that the steering operation state determination parameter A ^* is a positive value and the absolute value | ω _h | of the steering wheel angular velocity is greater than a predetermined threshold ε _0. Check whether or not. If the above condition is satisfied (Yes), the process proceeds to step S45, and the target pinion angle correction amount calculation unit 12c sets IFLAG = + 1 (the steering wheel is increased), and the process proceeds to step S50.
If the condition is not satisfied in step S44 (No), the process proceeds to step S46, and the target pinion angle correction amount calculation unit 12c has a negative value for the steering operation state determination parameter A ^* and the absolute value of the steering wheel angular velocity. It is checked whether or not a condition that | ω _h | is larger than a predetermined threshold value ε ₀ is satisfied.

If the condition is satisfied in step S46 (Yes), the process proceeds to step S47, and the target pinion angle correction amount calculation unit 12c sets IFLAG = -1 (handle return), and the process proceeds to step S50.
If the condition is not satisfied in step S46 (No), the process proceeds to step S48, and the target pinion angle correction amount calculation unit 12c determines whether or not the absolute value | ω _h | of the steering wheel angular velocity is equal to or less than a predetermined threshold ε _0. To check.
In step S48, when | ω _h | is equal to or smaller than the predetermined threshold value ε ₀ (Yes), the process proceeds to step S49, and the target pinion angle correction amount calculation unit 12c sets IFLAG = 0 (handle stop), and then proceeds to step S50. . In step S48, when | ω _h | is larger than the predetermined threshold value ε ₀ (No), the process proceeds to step S45.

In step S50, the target pinion angle correction amount calculation unit 12c checks whether IFLAGC = 0. If IFLAGC = 0 (Yes), the process proceeds to step S51. If IFLAGC ≠ 0 (No), the process proceeds to step S36 according to the code (C). Here, since it is immediately after IG ON, it will progress to step S51.
In step S51, the target pinion angle correction amount calculation unit 12c corrects the correction amount Δθ _C2 = 0.0.
Then, it is checked whether IFLAGB is a positive value (step S52). If FLAGB is a positive value in step S52 (Yes), the process proceeds to step S53, and the target pinion angle correction amount calculation unit 12c changes the flag indicating immediately after IG ON (IFLAGC = 1), and then proceeds to step S54. If FLAGB is not a positive value in step S51 (No), the process proceeds to step S54.

In step S54, the target pinion angle correction amount calculation unit 12c sets the corrected target pinion angle θ _CTP as θ _TP + Δθ _C2 (θ _CTP = θ _TP + Δθ _C2 ). Next, the process proceeds to step S55 according to the symbol (A).
In step S55, the target pinion angle correction amount calculation unit 12c sets the previous correction amount Δθ _C1 = Δθ _C2 and IFLAGA = IFLAGB, and returns to step S42 according to the sign (B).
Here, step S42~ step S50, the repetition of step S51~S55, for the first time steering operation state is repeated until the state of "turning-increasing" after the IG ON, during this period of correction amount Δθ _C2 is forced to zero. 0. This is because the tracking delay correction of the actual pinion angle θ _{P with} respect to the target pinion angle θ _TP immediately after the IG ON is performed is a quick response when changing from the position of the steering wheel angle θ _h when the vehicle is stopped. This means that the tracking delay correction is not performed regardless of the steering operation state.

When the steering operation state of “addition of the steering wheel” is once set after the IG is turned on (IFLAGC = 1), the process proceeds to step S56 in accordance with the symbol (C) in step S50, and the target pinion angle correction amount calculation unit 12c indicates the previous steering operation state. And whether or not the current flag indicating the steering operation state set in step S45, S47 or S49 is the same value (IFLAGB = IFLAGA?).
If it is the same in step S56 (Yes), the process proceeds to step S57, and the target pinion angle correction amount calculation unit 12c checks whether the value of IFLAGB is +1, 0, or -1. When the value of IFLAGB is +1, 0 in step S57, the process proceeds to step S58, the target pinion angle correction amount calculation unit 12c sets the correction amount to be the same as the previous time (correction amount Δθ _C2 = Δθ _C1 ), and proceeds to step S63. . If the value of IFLAGB is −1 in step S57, the process proceeds to step S59, and the target pinion angle correction amount calculation unit 12c multiplies the previous correction amount Δθ _C1 by e ^−Δt (correction amount Δθ _C2 = Δθ). _C1 × e ^−Δt ), the process proceeds to step S63.
Incidentally, when IFLAGB = + 1, the previous correction amount Δθ _C1 = 0.0, and when IFLAGB = 0 or IFLAGB = −1, the value (θ _P −θ _TP) set later in step S61 is described later. ).

When IFLAGB ≠ IFLAGA in step S56 (No), the process proceeds to step S60, and the target pinion angle correction amount calculation unit 12c determines whether or not the flag IFLAGB indicating the steering operation state set in steps S45, S47, and S49 is a positive value. To check. If the value is positive (Yes), the process proceeds to step S62. If the value is not positive (No), the process proceeds to step S61. In step S61, the target pinion angle calculation unit 12a sets the correction amount Δθ _C2 = θ _P −θ _TP and proceeds to step S63.

When the result is Yes in step S60 and the process proceeds to step S62, the target pinion angle correction amount calculation unit 12c sets the correction amount Δθ _C2 = 0.0, and the process proceeds to step S63.

In step S63, the adding unit 12d adds the target pinion angle calculation unit step to the target pinion angle theta _TP calculated in 12a S58, S59, S61, the current correction amount [Delta] [theta] _C2 set in either S62, The corrected target pinion angle θ _CTP is used (θ _CTP = θ _TP + Δθ _C2 ).
In step S64, the target pinion angle correction amount calculation unit 12c registers the current correction amount Δθ _C2 used as the previous correction amount Δθ _C1 for the next iteration (Δθ _C1 = Δθ _C2 ), and uses it for the next iteration. The flag of the current steering operation state used as the flag of the previous steering operation state is registered (IFLAGA = IFLAGB). In step S65, the target pinion angle correction amount calculation unit 12c checks whether or not IG is OFF. If IG is OFF (Yes), the series of processing ends, and if not IG OFF (No), step Returning to S42, a series of processes of steps S42 to S50 and S56 to S65 are repeated.

Hereinafter, in the flow of control after step S56, the value of the current flag IFLAGB indicating the steering operation state changes from the value of the previous flag IFLAGA and remains in the new value state for a while. The transition of the value of the correction amount Δθ _c2 will be described in an easy-to-understand manner.

(1) First, a case will be described in which the steering operation state (IFLAGB = + 1) is once entered after turning on the IG, and then the state of IFLAGB = + 1 continues for a while.
In that case, IFLAGB = + 1 in steps S42 to S49, the process proceeds from step S50 to step S56, IFLAGB = IFLAGA = + 1, the process proceeds to steps S57 and S58, and then the process proceeds to step S63.
In step S63, the current correction amount Δθ _C2 (= Δθ _C1 = 0.0) set in step S58 is added to the target pinion angle θ _TP through steps S51 (Δθ _C2 = 0.0) and step S55, The corrected target pinion angle θ _CTP is used (θ _CTP = θ _TP + Δθ _C2 ).
In step S64, Δθ _C1 = Δθ _C2 is set, and the flag of the current steering operation state is set as the flag of the previous steering operation state used for the next iteration (IFLAGA = IFLAGB).
Next, the process proceeds to step S65, where the target pinion angle correction amount calculation unit 12c checks whether or not IG is OFF. If IG is OFF (Yes), the series of processing ends, and if not IG OFF (No), Return to step S42 according to the code (D) and repeat.

(2) Next, after “IG ON”, the steering operation state “IFLAGB = + 1” is once entered, and after that, the state of IFLAGB = + 1 continues for a while and then IFLAGB ≠ + 1 (0 or −1). Will be described.
In this case, IFLAGB = + 1 in steps S42 to S49, and the process proceeds from step S50 to step S56. In step S56, IFLAGA ≠ IFLAGB (No), and the process proceeds to step S60, where the flag indicating the current steering operation state is a positive value. Check whether or not (IFLAGB> 0?).
If the value is positive (Yes) in step S60, the process proceeds to step S62. If the value is not positive (No), the process proceeds to step S61.
Here, as described above, since IFLAGB is not a positive value, No in step S60, the process proceeds to step S61, the correction amount Δθ _C2 = θ _P −θ _TP , and the process proceeds to step S63. This correction amount Δθ _C2 = θ _P −θ _TP is coupled with θ _CTP = θ _TP + Δθ _C2 in step S63, and at this point, the actual pinion angle θ _P is delayed following the target pinion angle θ _TP . This means that the current actual pinion angle θ _P itself is replaced with the current corrected target pinion angle θ _CTP .

  Thereafter, as described above, the process proceeds to steps S63 to S65, and returns to step S42 to perform a series of repetitive processes.

(3) Next, the case where the steering operation state (IFLAGB = + 1) is changed from the steering operation state “IFLAGB = + 1” to “steering wheel turning back” and the state continues for a while will be described. .
In this case, IFLAGB = −1 in steps S42 to S49, the process proceeds from step S50 to step S56, IFLAGA = IFLAGB = −1, the process proceeds to steps S57 and S59, and the target pinion angle correction amount calculation unit 12c calculates the correction amount. Δθ _C2 = Δθ _c1 × e ^−Δt
Here, Delta] t of e ^-.DELTA.t is relative to the target pinion angle theta _TP actual pinion angle theta _P set at the first timing has shifted to the steering state of IFLAGB = -1 is set ( "steering returning") in step S61 This means that the correction amount Δθ _C2 is attenuated by a factor of e ^{−Δt by} a predetermined time step Δt for each repetition count with respect to the correction amount Δθ _C2 for the tracking delay.
While steering operation state of the "steering returning" is continued, in accordance with the new steering wheel angle theta _h, the target transfer ratio G _T is set, is newly updated is also the target pinion angle theta _TP accordingly However, the absolute value of the correction amount Δθ _C2 added to the new target pinion angle θ _TP decreases each time step S59 is repeated.
After step S59, the process proceeds to steps S63 to S65 as described above, and returns to step S42 to perform a series of iterative processes.

(4) Next, a case will be described in which the steering operation state (IFLAGB = + 1) in the “steering wheel increase” state is changed to the steering operation state (IFLAGB = 0) in the “steering wheel stop” state, and this state continues for a while.
IFLAGB = 0 becomes in step S42～S49, the process proceeds from step S50 to step S56, IFLAGA = at IFLAGB = 0, the process proceeds to step S57, S58, the target pinion angle correction amount calculation unit 12c, the correction amount [Delta] [theta] _C2 = [Delta] [theta] _c1 And
Here, while the steering operation state of “steering wheel stop” continues, the target pinion angle θ _TP is also updated with the same value, but the correction amount Δθ _C2 added to the target pinion angle θ _TP is determined in step S59. This means that the same value set once in step is used every time step S58 is repeated. That is, the corrected target pinion angle θ _CTP is maintained at the same value, and the amount that the actual pinion angle θ _P is delayed following the target pinion angle θ _TP continues to be canceled.
After step S58, the process proceeds to steps S63 to S65 as described above, and returns to step S42 to perform a series of iterative processes.

(5) Finally, from the steering operation state of “steering wheel turning back” (IFLAGB = −1) or the steering operation state of “steering wheel stop” (IFLAGB = 0), the steering operation of “addition of steering wheel” (IFLAGB = + 1) A case where the state is changed will be described.
In steps S42 to S49, IFLAGB = + 1, and the process proceeds from step S50 to step S56. If IFLAGA = 0 or -1 and IFLAGB = + 1, the process proceeds to step S60, and the process further proceeds to step S62.
In step S62, the correction amount Δθ _C2 = 0.0, and the process proceeds to step S63. And as mentioned above, it progresses to step S63-S65, returns to step S42, and performs a series of repetition processes.

In the state of the quick ratio, the driver's rapid steering handle 2 (see FIG. 1) steers the motor angle θ _vm quickly due to insufficient output torque of the transmission ratio variable motor 33 (see FIG. 1). It becomes impossible to follow the angle θ _Tvm . Therefore, when stopping the operation of the steering wheel 2 at time t ₃ as in the comparative example shown in (a) of FIG. 13, the actual motor angle theta _vm as the case of the conventional follow the target motor angle theta _Tvm Since the control is continued, the turning of the steered wheels continues, and the driver feels uncomfortable through the behavior of the vehicle and the steering reaction force. If you stop the operation of the steering wheel 2 at time t ₃ as shown in (b) of FIG. 13 according to the modification of this embodiment, the target motor angle theta _Tvm is matched to the actual motor angle theta _vm, rolling The movement of the steering wheel stops and does not give such a sense of incongruity.

In the quick ratio state, when the driver turns back in a narrow alley or turns back at the time of entering the garage, the steering operation state in which the steering handle 2 repeats “increase steering wheel” and “returning steering wheel” continues. When the steering wheel angle θ _h as shown in FIG. 16A or the steering wheel angular velocity ω _h as shown in FIG. 16B is set, the flag IFLGB indicating the steering operation state at that time is as shown in FIG. To change. Here, because of the continuous operation, only the first “steering wheel stop” steering operation state when the vehicle is stopped is determined as IFLAGB = 0, and other time points are determined as IFLAGB = + 1 or IFLAGB = −1.
Then, in the steering operation state of “steering wheel turning back” after the steering operation state of “increasing steering wheel turning” is measured, a correction amount Δθ is obtained when a follow-up delay of the actual pinion angle θ _P with respect to the target pinion angle θ _TP occurs. _{Although C2} is set, as shown by the solid line in FIG. 16 (d), the correction amount gradually attenuates during the repetitive processing, and the correction amount Δθ _{C2 at the} timing of switching to the steering operation state of “addition of steering wheel increase”. The jump amount of the correction amount Δθ _C2 when the value is replaced with 0.0 becomes small. Therefore, the uncomfortable feeling given to the driver can be eliminated. Incidentally, the control in the flowchart of FIG. 12 is indicated by a two-dot chain line in FIG.
As a result, the amount of discomfort to the driver is reduced.

<< Third Embodiment >>
Next, a third embodiment will be described with reference to FIGS. In the present embodiment, the target motor angle setting unit 12B in the second embodiment is changed to a target motor angle setting unit 12C, and the others are the same as those in the second embodiment or its modification.
FIG. 17 is a block functional configuration diagram of a target motor angle setting unit in the third embodiment.
18 and 19 are flowcharts showing the flow of control for changing the target transmission ratio in the target motor angle setting unit.
As shown in FIG. 17, the target motor angle setting unit 12C in the present embodiment includes a steering state determining unit 12e, a target transmission ratio changing unit 12f, and a target motor angle producing unit 12g.

  The steering state determination unit 12e determines whether or not the steering operation of the steering handle 2 by the driver is a state immediately after IG ON, and inputs a flag (IFLAGC) indicating the state to the target transmission ratio changing unit 12f (immediately after IG ON) If not, IFLAGC = 1). In addition, the steering state determination unit 12e determines whether the state is “addition of a steering wheel”, “returning a steering wheel”, or “stopping a steering wheel”. (IFLAGB = + 1) is set, a flag (IFLAGB = -1) is set in the case of "handle switchback", and a flag (IFLAGB = 0) in the case of "handle stopped" ) And is input to the target transmission ratio changing unit 12f.

The target transmission ratio changing unit 12f is (1) in the state immediately after IG ON (IFLGGC = 0), in any of the steering operation states of “steer wheel increase”, “steer wheel increase”, and “steer wheel stop”, it outputs as the target transfer ratio G _X to the target motor angle calculating section 12g of the target transfer ratio G _T set according to the vehicle speed VS in the target transfer ratio setting section 11.
The target transmission ratio changing unit 12f is not in a state immediately after IG ON (when IFLGC = 1),
(2) When the “steer handle is increased” or the steering wheel is substantially straight, the flag indicating “handle return” or “stop handle” after the steering operation of “add handle is increased” is reset (IFLAGD = 0), the target transfer ratio G _T set to output as the target transfer ratio G _X to the target motor angle calculating section 12g in accordance with the vehicle speed VS in the target transfer ratio setting section 11,
(3) In the case of “handle return” or “handle stop” after “addition of handle”, a flag indicating “handle return” or “handle stop” after steering operation of “addition of handle” is set. setting (IFLAGD = 1) and, at its first point, the steering wheel angle theta _h and the actual pinion angle theta target transmission ratio to the target motor angle calculating section 12g calculates the target transfer ratio G _X determined by the ratio of _P G _X And the same target transmission ratio G _X is continuously output to the target motor angle calculation unit 12g while IFLAGD = 1 continues.

The target motor angle calculation unit 12g calculates the target motor angle θ _Tvm according to the equation (4) using the target transmission ratio G _X. However, it replaced the target transfer ratio G _T to the target transfer ratio G _X in the formula (4).

18 and 19 are flowcharts showing the flow of control for correcting the target transmission ratio in the target motor angle setting unit.
This process is mainly performed by the steering state determination unit 12e.
When the target motor angle setting unit 12C is IG ON, the target transmission ratio changing unit 12f sets the flag indicating immediately after IG ON as 0 (IFLAGC = 0) as an initial setting, and “handle return” after “addition of steering wheel”. Alternatively, a flag (IFLAGD) indicating that the “handle is stopped” state is set to 0 (IFLAGD = 0) (step S71).

In step S72, the steering state determination unit 12e reads the steering wheel angle θ _h , the actual pinion angle θ _P , and the steering wheel angular velocity ω _h .
In step S73, the steering state determination unit 12e calculates a steering operation state determination parameter A ^* (A ^* = θ _h × ω _h ).

In step S74, the steering state determination unit 12e satisfies whether or not the condition that the steering operation state determination parameter A ^* is a positive value and the absolute value | ω _h | of the steering wheel angular velocity is greater than a predetermined threshold ε ₀ is satisfied. Check. If the condition is satisfied (Yes), the process proceeds to step S75, and the steering state determination unit 12e sets IFLAG = + 1 (the steering wheel is increased), and the process proceeds to step S80.
If the condition is not satisfied in step S74 (No), the process proceeds to step S76, and the steering state determination unit 12e determines that the steering operation state determination parameter A ^* is a negative value and the absolute value of the steering wheel angular velocity | ω _h. It is checked whether or not the condition that | is larger than a predetermined threshold ε ₀ is satisfied.

In step S76, if the condition is satisfied (Yes), the process proceeds to step S77, and the steering state determination unit 12e sets IFLAG = -1 (steering back) and proceeds to step S80.
In step S76, if not satisfy the condition (No), the process proceeds to step S78, the steering state determining unit 12e, the absolute value of the steering wheel angular velocity | omega _h | is checked whether a predetermined threshold value epsilon ₀ or less.
In step S78, when | ω _h | is equal to or smaller than the predetermined threshold value ε ₀ (Yes), the process proceeds to step S79, and the steering state determination unit 12e sets IFLAG = 0 (steering wheel stop), and proceeds to step S80. In step S78, when | ω _h | is larger than the predetermined threshold value ε ₀ (No), the process proceeds to step S75, and further proceeds to step S80.

In step S80, the target transmission ratio changing unit 12f checks whether IFLAGC = 0. If IFLAGC = 0 (Yes), the process proceeds to step S81. If IFLAGC ≠ 0 (No), the process proceeds to step S84 according to the code (E). Here, since it is immediately after IG ON, it will progress to step S81.
In step S81, the target transmission ratio changing unit 12f checks whether IFLAGB is positive. If it is positive (Yes), the process proceeds to step S82. If it is not positive (No), the process proceeds to step S83.
In step S82, the target transmission ratio changing unit 12f changes the flag indicating immediately after IG ON (IFLAGC = 1), and proceeds to step S83.

At step S83, the target transfer ratio changing section 12f outputs the target transfer ratio G _T from the target transfer ratio setting section 11 read in step S72 as a target transfer ratio G _X directly, the target motor angle calculating section 12g. Then, the process returns to step S72.
Here, the repetition of Steps S72 to S80 and Steps S81 and S83 is repeated until the steering operation state becomes “additional” for the first time after the IG is turned on, and the target motor angle is calculated from the target transmission ratio changing unit 12f during this period. target transfer ratio G _X to be output section 12g is left of the target transfer ratio G _T. This is, to perform the following delay correction of the actual pinion angle theta _P with respect to the target pinion angle theta _TP obtained from the target transfer ratio G _T immediately after IG ON, the attempt to change the position of the steering wheel angle theta _h when the vehicle is stopped when, therefore inconvenient to cause a rapid response, regardless of the steering operation state, the target transfer ratio G _X means that is not performed while the follow delay correction of the target transfer ratio G _T.

It becomes once the steering operation state of the "steering wheel widening" after IG ON (IFLAGC = 1), the flow advances to step S84 according to the sign (E) in step S80, the target transfer ratio changing section 12f the absolute value of the steering wheel angle theta _h Whether or not is greater than the threshold value θ _hth . When it is larger than the threshold value θ _hth (Yes), the process proceeds to step S86, and when it is equal to or _smaller than the threshold value θ _hth (No), the process proceeds to step S85.
Step S85 The target transfer ratio changing section 12f outputs the target transfer ratio G _T from the target transfer ratio setting section 11 read in step S72 as a target transfer ratio G _X directly, the target motor angle calculating section 12g, Step S88 Proceed to
When the process proceeds to Yes in step S84 and proceeds to step S86, the target transmission ratio changing unit 12f checks whether IFLAGB is positive. If positive (Yes), the process proceeds to step S87, outputs the target transfer ratio G _T from the target transfer ratio setting section 11 read in step S72 as a target transfer ratio G _X directly, the target motor angle calculating section 12g, Proceed to step S88. In step S88, the target transmission ratio changing unit 12f sets IFLAGD = 0, and then proceeds to step S94.

  If the result is No in step S86 and the process proceeds to step S89, the target transmission ratio changing unit 12f checks whether IFLAGD = 1. If IFLAGD = 1 (Yes), the process proceeds to step S91. If IFLAGD ≠ 1 (No), the process proceeds to step S90. At first, since IFLAGD = 0 is set as an initial value in step S71, the process proceeds to step S90 here.

In step S90, the target transmission ratio changing unit 12f outputs the target transmission ratio G _X as G _X = θ _h / θ _P to the target motor angle calculation unit 12g, and proceeds to step S92.
When the result is Yes in step S89 and the process proceeds to step S91, the target transmission ratio changing unit 12f outputs the target transmission ratio G _X as G _X = G _Xp to the target motor angle calculation unit 12g, and proceeds to step S92.

In step S92, the target transmission ratio changing unit 12f sets IFLAGD = 1, proceeds to step S93, and stores the current target transmission ratio G _X in the repetition as G _Xp .
In step S94, the target motor angle calculation unit 12g calculates the target motor angle based on the target transmission ratio G _X input from the target transmission ratio change unit 12f and outputs the target motor angle to the subtraction unit 13 (θ _Tvm = (1 / Β) · {(1 / G _X ) −α} θ _h ).
Then, in step S95, the target motor angle calculation unit 12C checks whether or not the IG is OFF. If the IG is OFF (Yes), the series of processing ends, and if the IG is not OFF (No), the code (F ) To return to step S72 and repeat a series of steps S72 to S80 and S84 to S95.

Hereinafter, in the flow of control after step S86, the value of the current flag IFLAGB indicating the steering operation state changes from +1 to -1 or 0, and the value of IFLAGB remains in the state of -1 or 0 for a while. The transition of the value of the target transmission ratio G _X during the iterative process will be described in an easy-to-understand manner.
In steps S73 to S79, IFLAGB = 0, −1, and the process proceeds from step S80 to step S84. If | θ _h |> θ _hth , the process proceeds to steps S86 and S89 for the first time after IFLAGB = + 1, because IFLAGD = 0. Proceeding to step S90, G _X = θ _h / θ _P is set, then IFLAGD = 1 is set at step S92, and the previous target transmission ratio G _Xp = G _X is repeated at step S93.

Then, through steps S94 and S95, in the next iteration, IFLAGB = 0, −1 again in steps S73 to S79, the process proceeds from step S80 to step S84, and when | θ _h |> θ _hth , the process proceeds to steps S86 and S89. Since IFLAGD = 1 in the previous iteration, the process proceeds to step S91 with Yes in step S89. In step S91, the target transmission ratio G _Xp in the previous iteration stored in step S93 of the previous iteration is set as the target transmission ratio G _X in the current iteration, and is output to the target motor angle calculation unit 12g.

That is, the target transmission ratio G _X is not updated while the steering operation state of “steering wheel stop” or “steering wheel turning back” continues after the steering operation state of “steering wheel increase”, and is set once in step S90. The same value is used every time step S91 is repeated. That is, the changed target transmission ratio G _X is maintained at the same value.

By the way, when the steering operation state of “steering wheel stop” or “steering wheel turning back” is entered after the steering operation state of “addition of steering wheel”, it is assumed that G _X = θ _h / θ _P in step S90. In the steering operation state of “addition of steering wheel”, the absolute value of the steering wheel angular velocity ω _h is large, and the target transmission ratio G _{X at} that time (the target transmission ratio G _T according to the vehicle speed VS set by the target transmission ratio setting unit 11) Even if the actual pinion angle θ _P is delayed following the target pinion angle θ _TP determined in accordance with the target pinion angle θ _TP , the actual pinion angle θ _P and the handle angle θ _{h at} that time Therefore, the target pinion angle θ _TP is adjusted to the current actual pinion angle θ _P by changing and setting to the new target transmission ratio G _X.

Then, the target motor angle calculating section 12g is, instead of the target transfer ratio G _T in equation (4), by substituting the target transfer ratio G _X changed in step S90, and calculates the target motor angle theta _Tvm, By outputting to the subtracting unit 13, as shown in FIG. 13B, it means that the target motor angle θ _Tvm is adjusted to the actual motor angle θ _vm, and if the steering operation of the steering handle 2 is stopped, The transmission ratio variable motor 33 is also stopped, and the change of the angle of the steered wheels is stopped at the same time, even though the steering operation state is changed from the “steering wheel increase” steering state to the “steering wheel stop” or “steering wheel turnback”. It is possible to prevent the pinion angle θ _P from being controlled to the “steering angle increase” side.

Then, in step S84, No and happens, Yes, the processing advances to step S86, further proceeds to step S87 in the steering state of "steering wheel widening" in step S86, then the first target transfer ratio G _X, at step S72 It switched to the target transfer ratio G _T corresponding to the read vehicle speed VS set by the target transfer ratio setting section 11.
Therefore, in step S84, the case where the absolute value of the steering wheel angle theta _h such that No is regarded as substantially straight below the threshold theta _hth, since a G _X = G _T, when returning the steering wheel 2 to the neutral, The turning angle of the steered wheels is also returned to the neutral position, so that there is no problem that the center deviation between the steering handle 2 and the steered wheels occurs.
It should be noted that when the steering operation is changed from “steering wheel return” to “steering wheel stop” and then the steering operation state is changed to “steering wheel increase”, the target transmission ratio G _Xp in the previous iteration is used. stop, since switching to the target transfer ratio G _T corresponding to the vehicle speed VS set by the target transfer ratio setting section 11 read in step S72, the variable transfer ratio mechanism 5 (see FIG. 1) returns to the original setting .

In the state of the quick ratio, the driver's rapid steering handle 2 (see FIG. 1) steers the motor angle θ _vm quickly due to insufficient output torque of the transmission ratio variable motor 33 (see FIG. 1). It becomes impossible to follow the angle θ _Tvm . Therefore, when stopping the operation of the steering wheel 2 at time t ₃ as in the comparative example shown in (a) of FIG. 13, the actual motor angle theta _vm as the case of the conventional follow the target motor angle theta _Tvm Since the control is continued, the turning of the steered wheels continues, and the driver feels uncomfortable through the behavior of the vehicle and the steering reaction force. If you stop the operation of the steering wheel 2 at time t ₃ as shown in (b) of FIG. 13 according to this embodiment, since the target motor angle theta _Tvm is matched to the actual motor angle theta _vm, movement of the steered wheels Will not stop and will not give such a sense of incongruity.

<< Fourth Embodiment >>
Next, a fourth embodiment of the present invention will be described with reference to FIG. 1 as appropriate with reference to FIGS. FIG. 20 is a functional configuration block diagram of a variable transmission ratio mechanism control ECU in the fourth embodiment. The variable transmission ratio mechanism control ECU 9D has a target transmission ratio setting unit 11, a target motor angle setting unit 12A, a subtraction unit 13, a position F / B control unit 14, a subtraction unit 15, a current F / B control unit 16, and multiplication as a mechanism block. Part 19.
Here, the target transmission ratio setting unit 11 and the target motor angle setting unit 12A correspond to the transmission ratio adjustment setting unit described in the claims, and the multiplication unit 19 and the correction count setting unit 20B are the steering torque adjustment settings described in the claims. Corresponding to the part.
In the present embodiment, the transmission ratio adjustment mode and the steering torque adjustment mode are not defined in the first embodiment, and the current of the transmission ratio variable motor 33 (see FIG. 1) is continuously corrected in the correction count 20B. In response to this, control is performed on the downstream side. The present embodiment has basically the same configuration as the first embodiment, but the correction count setting unit 20 included in the variable transmission ratio mechanism control ECU 9A in the first embodiment is simply replaced with the correction count 20B. is there. About the same structure as 1st Embodiment, the same code | symbol is attached | subjected and the overlapping description is abbreviate | omitted.

Unlike the first embodiment, the correction coefficient setting unit 20B in this embodiment receives a vehicle speed VS and a steering wheel angular velocity ω _h from a vehicle speed sensor (not shown) as shown in FIG. _h is not entered.
The correction coefficient setting unit 20B sets a correction coefficient K ₁ for the absolute value | ω _h | of the steering wheel angular velocity with reference to data of a continuous function (see FIG. 21) corresponding to the vehicle speed VS stored in the ROM.

The continuous function for determining the correction coefficient K ₁ having the absolute value | ω _h | of the steering wheel angular velocity shown in FIG. 21 as a variable is such that the correction coefficient K ₁ is monotonically linearly 1.0 when the absolute value | ω _h | It shows a characteristic that when it reaches -1.0, it saturates at -1.0.
By allowing a negative value to a correction factor K _1, the target current value I _T2 results correction coefficient K ₁ to the target current value I _T1 is multiplied by the multiplication unit 19 is reversed to the direction of the target current value I _T1 Is allowed. That is, the target motor angle θ _Tvm of the transmission ratio variable motor 33 in the quick ratio direction is allowed to be changed to the target motor angle θ _Tvm of the transmission ratio variable motor 33 in the slow ratio direction, and the steering reaction force is reduced. Let

Here, the value of the negative slope of the straight line at which the correction coefficient K ₁ decreases monotonously changes according to the vehicle speed VS. The smaller the vehicle speed VS, the larger the absolute value is set, and the larger the vehicle speed VS, the absolute value. Is set to a small value.
This target transfer ratio G _T set by the target transfer ratio setting section 11, as the vehicle speed VS is less reduced target transfer ratio G _T, that is, since the set quick ratio side, the stronger the degree of the quick ratio Even if the absolute value | ω _h | of the steering wheel angular velocity is small, the EPS motor 23 and the transmission ratio variable motor 33 of the electric power steering device 4 tend not to follow, so that the increase of the steering wheel angular velocity | ω _h | Change the correction amount greatly.

Next, referring to FIG. 22, the flow of control for setting the correction coefficient K ₁ in the correction coefficient setting unit 20B and outputting the target current value I _T2 in the multiplication unit 19 will be described with reference to FIG. 20 as appropriate.
Steps S101 to S103 in the flowchart described below are processed in the correction coefficient setting unit 20B, and steps S104 and S105 are processed in the multiplication unit 19. Incidentally, step S106 is performed in the overall control in the CPU 9a.
When the ignition switch (IG) is turned on, the variable transmission ratio mechanism control ECU 9D is activated, and the variable transmission ratio mechanism control program is started in the CPU 9a (see FIG. 20). Thereafter, steps S101 to S106 are repeated at a constant cycle.
In step S101, the vehicle speed VS, the steering angular velocity ω _h , and the target current value I _T1 output from the position F / B control unit 14 are read.

In step S102, the correction coefficient data corresponding to the vehicle speed VS read in step S101 is referred to. Specifically, for example, as shown in FIG. 20, several types of continuous functions with the absolute value | ω _h | of the steering angular velocity for determining the correction coefficient K ₁ as variables are prepared for different values of the predetermined vehicle speed VS. Then, a desired continuous function is obtained by interpolating according to the value of the vehicle speed VS read in step S101.

In step S103, the absolute value of the steering wheel angular velocity | sets the correction factor K ₁ corresponding to | omega _h.
In step S104, I _T2 = K ₁ × I _T1, and I _T2 is output as a target current value to the subtraction unit 15 (see FIG. 20) (step S105). Then, the process proceeds to step S106 to check whether or not the ignition switch is turned off (IG OFF?). If IG OFF (Yes), a series of control is terminated, and if not IG OFF (No). Returning to step S101, steps S101 to S106 are repeated.

Or the setting of the correction coefficient K ₁ in the correction coefficient setting unit 20B, and the end of the description of the series of the flow of control for outputting a target current value I _T2 of the multiplication unit 19.
According to this embodiment, there is no switching between the transmission ratio adjustment mode and the steering torque adjustment mode as in the first embodiment, and when the vehicle speed VS is low, the absolute value of the steering wheel angular velocity | ω _h | Accordingly, the target current of the transmission ratio variable motor 33 is corrected, and the steering reaction force applied to the driver during the steering operation of the driver's rapid steering handle 2 (see FIG. 1) can be reduced.

In the above first to fourth embodiments and their modifications, a differential gear mechanism (planetary gear mechanism 31) using a planetary gear as a transmission ratio variable mechanism is assumed. The application is not limited to this, and the present invention can be applied to a general apparatus including an actuator for adjusting the steering wheel angle and the pinion angle.
Further, although the electric power steering device 4 is assumed as the steering force assisting mechanism, the application of the present invention is not limited to this, and can be similarly applied to a hydraulic power steering device.

1 is a schematic configuration diagram of a steering device according to a first embodiment of the present invention. It is a functional block diagram of variable transmission ratio mechanism control ECU. It is a figure which shows the value of the target transmission ratio set according to a vehicle speed. It is a figure which shows the value of the correction coefficient set according to the absolute value of steering wheel angular velocity. It is a flowchart which shows the flow of the switching control between the transmission ratio adjustment mode and torque adjustment mode in a correction coefficient setting part, and the setting control of the 2nd target electric current value in torque adjustment mode. It is a functional block diagram of variable transmission ratio mechanism control ECU of a comparative example. (A) is a figure which shows the time transition of steering wheel angular velocity (omega) _h , (b) is a figure which shows the time transition of the value of the target electric current value _IT1 and the target electric current value _IT2 , (c) a diagram illustrating the evolution in time of the steering torque value T _h. 6 is a flowchart showing a flow of switching control between a transmission ratio adjustment mode and a torque adjustment mode in a correction coefficient setting unit in a modification of the first embodiment and a setting control of a second target current value in the torque adjustment mode. . It is a figure which shows the value of the correction coefficient set according to the absolute value of a steering torque value. FIG. 6 is a functional block diagram of a variable transmission ratio mechanism control ECU in a steering apparatus according to a second embodiment of the present invention. It is a detailed functional block diagram of a target motor angle setting unit. It is a flowchart which shows the flow of control which correct | amends the target pinion angle in a target motor angle setting part. (A) is a figure which shows the time transition of real motor angle (theta) _vm and target motor angle (theta) _Tvm of the motor for variable transmission ratio in a comparative example, (b) is an actual figure of the motor for variable transmission ratio in 2nd Embodiment. It is a figure which shows the time transition of motor angle (theta) _vm and target motor angle (theta) _Tvm . It is a flowchart which shows the flow of control which correct | amends the target pinion angle in a target motor angle setting part. It is a flowchart which shows the flow of control which correct | amends the target pinion angle in a target motor angle setting part. (A) is a graph showing the time transition of the steering wheel angle θ _h , (b) is a graph showing the time transition of the steering wheel angular velocity ω _h , and (c) is a change of the flag value indicating the steering operation state. (D) is a graph showing the time transition of the correction amount Δθ _C2 . It is a block functional block diagram of the target motor angle setting part in 3rd Embodiment. It is a flowchart which shows the flow of control which changes the target transmission ratio in a target motor angle setting part. It is a flowchart which shows the flow of control which changes the target transmission ratio in a target motor angle setting part. It is a functional block diagram of variable transmission ratio mechanism control ECU in 4th Embodiment. It is a figure which shows the value of the correction coefficient set according to the absolute value of steering wheel angular velocity. It is a flowchart which shows the flow of the switching control between the transmission ratio adjustment mode and torque adjustment mode in the correction coefficient setting part in 4th Embodiment, and the setting control of the 2nd target electric current value in torque adjustment mode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering device 2 Steering handle 3 Rack & pinion mechanism 4 Electric power steering device (electric power steering)
5 Variable Transmission Ratio Mechanism 7 Pinion Angle Sensor 9, 9A, 9B, 9C, 9D Variable Transmission Ratio Mechanism Control ECU
9a CPU
11 Target transmission ratio setting section (transmission ratio adjustment setting section)
12A Target motor angle setting unit (transmission ratio adjustment setting unit)
12B, 12C Target motor angle setting section 12a Target pinion angle calculation section 12b, 12g Target motor angle calculation section 12c Target pinion angle correction amount calculation section 12d Addition section 12e Steering state determination section 12f Target transmission ratio change section 13, 15 Subtraction section 14 Position F / B control unit 16 Current F / B control unit 17 Motor drive circuit 18 Current sensor 19 Multiplication unit (steering torque adjustment setting unit)
20 Correction coefficient setting unit 20B Correction coefficient setting unit (steering torque adjustment setting unit)
21 Torque sensor 23 EPS motor 25 ECU
31 planetary gear mechanism 33 motor for variable transmission ratio 35 motor angle sensor

Claims (7)

In the steering device that changes the steering angle transmission ratio of the steering wheel with respect to the turning angle of the steered wheels by the variable transmission ratio mechanism, and generates an assisting force during steering by the electric power steering,
A transmission ratio adjustment mode for setting a rotation angle of a transmission ratio variable motor used in the variable transmission ratio mechanism and a steering force of the steering handle so that the transmission ratio is set to a target transmission ratio corresponding to a vehicle speed. A switching means for switching between a steering torque adjustment mode for reducing a current for driving the transmission ratio variable motor so as to reduce,
When switching from the transmission ratio adjustment mode to the steering torque adjustment mode, the steering device is controlled such that a current value to the transmission ratio variable motor continuously changes. Furthermore, it has a steering operation state information acquisition means for acquiring steering operation state information indicating the operation state of the steering wheel,
The switching means is
When switching from the transmission ratio adjustment mode to the steering torque adjustment mode, a correction coefficient is set based on the acquired steering operation state information and a continuous function using the steering operation state information as a variable, and the steering torque is set. The second target current value obtained by multiplying the first target current value in the adjustment mode by the set correction coefficient is set as a current value to the transmission ratio variable motor. Item 2. The steering device according to Item 1.   The steering apparatus according to claim 2, wherein the steering operation state information is a steering speed of the steering wheel.   The steering apparatus according to claim 2, wherein the steering operation state information is a steering torque value.   The steering apparatus according to claim 2, wherein the steering operation state information is an instruction current value for an assist motor used for the electric power steering and serving as a source of the auxiliary force. In the steering device that changes the steering angle transmission ratio of the steering wheel with respect to the turning angle of the steered wheels by the variable transmission ratio mechanism, and generates an assisting force during steering by the electric power steering,
A transmission ratio adjustment mode for setting a rotation angle of a transmission ratio variable motor used in the variable transmission ratio mechanism and a steering force of the steering handle so that the transmission ratio is set to a target transmission ratio corresponding to a vehicle speed. A switching means for switching between a steering torque adjustment mode for reducing a current for driving the transmission ratio variable motor so as to reduce,
When the steering of the steering wheel is stopped or the steering direction is switched, the current of the transmission ratio variable motor is controlled so that the turning angle does not increase in the previous steering direction. Steering device. In the steering device that changes the steering angle transmission ratio of the steering wheel with respect to the turning angle of the steered wheels by the variable transmission ratio mechanism, and generates an assisting force during steering by the electric power steering,
A transmission ratio adjustment setting unit for setting a rotation angle of a transmission ratio variable motor used in the variable transmission ratio mechanism so that the transmission ratio is set to a target transmission ratio corresponding to a vehicle speed;
A steering torque adjustment setting unit for reducing a current for driving the transmission ratio variable motor so that a steering force of the steering wheel is reduced;
The steering device according to claim 1, wherein the control amount output from the steering torque adjustment setting unit changes continuously.

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