JP2009101885A - Transmission ratio varying device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission ratio varying device for suppressing the influences of outer force input via a steering wheel on a steering system. <P>SOLUTION: An ECU controls the rotating drive of a motor in accordance with a proportional controlled variable obtained by multiplying a deviation between an ACT target angle as a target steering angle set depending on a vehicle speed V of a vehicle and a motor rotating angle θm by a proportional gain Kp. At this time, the ECU gradually reduces the proportional gain Kp when a gain setting part determines in accordance with the steering angle θs that the steering held condition of a steering wheel is continued for a fixed time, specifically when the condition of an angle variation Δθs or less that an angle variation ¾θs-θs<SB>1</SB>¾ of the steering angle is determined to be the steering held condition is continued for a fixed time. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a transmission ratio variable device that changes a turning angle of a steered wheel with respect to a steering angle of a steering according to a driving situation.

2. Description of the Related Art Conventionally, as a transmission ratio variable device that changes a steering angle of a steered wheel with respect to a steering angle of a steering according to a driving situation, for example, a vehicle steering device shown in Patent Document 1 is known. The vehicle steering apparatus includes a variable gear ratio actuator (transmission ratio variable mechanism) having a differential mechanism provided on a steering shaft and a motor that drives the differential mechanism. The variable gear ratio actuator speeds up (or decelerates) the rotation of the steering shaft accompanying the steering operation, thereby varying the gear ratio (transmission ratio) of the steered wheels with respect to the steering angle.
JP 2005-170129 A

In general, in a transmission ratio variable device, position control for driving a motor is performed such that a turning angle of a steered wheel accompanying a steering operation becomes a target steering angle set according to a vehicle speed or the like.
By the way, when a large external force (reverse input) is input that changes the turning angle of the steering wheel when the steering wheel of a vehicle equipped with such a transmission ratio variable device collides with a curb or the like, However, the position control generates a torque for preventing the change of the steering angle of the steered wheels. For this reason, a case where the reverse input acts on a steering system such as a differential mechanism disposed between the motor and the steered wheel and the steering system is damaged may be considered. Further, when the strength of the steering system is increased so as not to be damaged even when a large reverse input as described above is input, there is a problem that each component such as a differential mechanism constituting the steering system is increased in size.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a transmission ratio variable device capable of suppressing the influence on the steering system due to the external force input via the steering wheel. There is to do.

In order to achieve the above object, in the variable transmission ratio device according to claim 1, the vehicle steering system (14, 16) connecting the steering wheel (12) and the steering wheels (FR, FL). , And a transmission ratio variable mechanism (31) that can change the transmission ratio between the steering wheel side input shaft (14) and the steering wheel side output shaft (16) by the rotational drive of the motor (32). ), Steering angle detection means (18) for detecting the steering angle (θs) of the input shaft, vehicle speed detection means (26) for detecting the vehicle speed (V) of the vehicle, and rotation angle (θm) of the motor And a proportional control amount (εp) obtained by multiplying the deviation between the target steering angle (θta ₀ ) set according to the vehicle speed and the rotation angle by a proportional gain (Kp). Based on this, the rotational drive of the motor is controlled A transmission ratio variable device (30) comprising: a motor control means (40), wherein the motor control means is configured to maintain the steering wheel holding state for a predetermined time based on the steering angle. When the determination is made, it is technically characterized by comprising a gain setting means (56) for decreasing and setting the proportional gain.

  In the first aspect of the invention, the motor control means controls the rotational drive of the motor based on a proportional control amount obtained by multiplying the deviation between the target steering angle set according to the vehicle speed of the vehicle and the rotational angle of the motor by a proportional gain. To do. At this time, when it is determined by the gain setting means that the steered state of the steering wheel continues for a certain time based on the steering angle of the input shaft, for example, the amount of change in the steering angle is maintained. When the state that is equal to or less than the angle change amount determined to be the rudder state is continued for a certain period of time, the proportional gain is decreased and set.

As a result, a large external force (reverse input) that changes the turning angle of the steering wheel when the steering wheel of the vehicle collides with a curb or the like when the steering wheel is in a steering state is input via the steering wheel. Even in this case, since the proportional gain is made smaller than the normal value, the steering followability by the motor is temporarily reduced, and the generation of torque to prevent the change of the steered wheel turning angle is generated. Can be suppressed. For this reason, a large external force does not act on a steering system such as a differential mechanism disposed between the motor and the steering wheel.
Therefore, the influence on the steering system due to the external force input via the steering wheel can be suppressed.

  In the invention of claim 2, the gain setting means increases the decrease amount of the proportional gain as the vehicle speed of the vehicle increases. In general, when the vehicle speed is low, the steering frequency is higher than when the vehicle speed is high. Therefore, when the steering frequency is low, that is, when the vehicle speed is high, the amount of decrease in the proportional gain is increased to quickly shift to a state where the generation of torque that hinders the change in the steering angle as described above can be suppressed. can do. On the other hand, when the steering frequency is high, that is, when the vehicle speed is low, the amount of decrease in the proportional gain is reduced, so that even when the proportional gain is decreased in the steered state, the non-steered state (steered state ), It is possible to quickly return the steering followability by the motor.

  In the invention of claim 3, the motor control means controls the rotational drive of the motor based on the integral control amount obtained by multiplying the deviation between the target steering angle and the rotation angle of the motor by the integral gain and the above-described proportional control amount. At this time, the gain setting means is configured to input an external force (reverse input) to the steering system via the steered wheels when it is determined that the steering wheel holding state continues for a predetermined time based on the steering angle. The integral gain is reduced and set while the external force affects the steering system.

  As a result, when the reverse input is input to the steering system via the steered wheels when the steering wheel is in the steering holding state, the integral gain is reduced, so that the steering followability of the motor, which has been reduced by the reduction of the proportional gain, is further reduced. Can do. When the reverse input does not affect the steering system, the steering followability by the motor can be recovered by increasing the integral gain to, for example, a normal value.

  Hereinafter, a variable transmission ratio device according to an embodiment of the present invention will be described with reference to the drawings for a vehicle control device. FIG. 1A is an explanatory diagram showing an outline of the configuration of the vehicle control device 10 to which the transmission ratio variable device 30 according to the present embodiment is applied, and FIG. 1B is a circuit block showing a configuration example of the ECU 40 and the like. FIG. FIG. 2 is a functional block diagram relating to the PI control system of the motor 32 according to the present embodiment.

  As shown in FIG. 1A, the vehicle control device 10 mainly includes a steering wheel 12, a first steering shaft 14, a second steering shaft 16, a torque sensor 18, a pinion gear 20, a rack shaft 22, a rod 24, and a transmission. It is comprised from the ratio variable apparatus 30, ECU40 grade | etc.,.

  The steering wheel 12 is fixed to the first steering shaft 14, the first steering shaft 14 is connected to the input side of the transmission ratio variable device 30, and the second steering shaft 16 is connected to the output side of the transmission ratio variable device 30. Has been. The torque sensor 18 detects the steering angle θs and the steering torque from the torsion amount of a not-illustrated torsion bar provided in the middle of the first steering shaft 14, and outputs detection signals corresponding to the steering angle and the steering torque to the ECU 40. To do.

  The pinion gear 20 at the tip of the second steering shaft 16 meshes with the rack shaft 22, and the rotational motion of the second steering shaft 16 is converted into the linear motion of the rack shaft 22. A rod 24 is connected to both ends of the rack shaft 22, and steering wheels FR and FL are connected to the end of the rod 24 via a knuckle (not shown). As a result, when the second steering shaft 16 rotates, the turning angle θt of the steered wheels FR, FL can be changed via the rack shaft 22, the rod 24, etc. Therefore, the rotation amount and the rotation of the second steering shaft 16 can be changed. Steering wheels FR and FL according to the direction can be steered.

  The transmission ratio variable device 30 includes a differential mechanism 31 that connects the first steering shaft 14 and the second steering shaft 16, and a motor 32 that drives the differential mechanism 31. The motor 32 rotates forward and backward by being controlled by the ECU 40, and the differential mechanism 31 transmits the rotation of the first steering shaft 14 to the second steering shaft 16 and decelerates the rotation of the motor 32 to perform the second steering. It is transmitted to the shaft 16.

  That is, the transmission ratio variable device 30 adds the rotation driven by the motor to the rotation of the first steering shaft 14 accompanying the steering operation input to the differential mechanism 31 and transmits the rotation to the second steering shaft 16, thereby The rotation of the shaft 22 is increased (or decelerated). Note that “addition” in this case is defined to include not only addition but also subtraction, and so on.

  That is, the transmission ratio variable device 30 is controlled by the ECU 40, and the steering angle of the steered wheels FR, FL based on the motor drive (the motor rotation angle θm) is controlled by the steering angle of the steered wheels FR, FL based on the steering operation (steering angle θs). Is added to vary the transmission ratio of the steering wheels FR and FL with respect to the steering angle θs.

Next, the electrical configuration of the ECU 40 that controls the drive of the motor 32 will be described with reference to FIG.
As shown in FIG. 1B, the ECU 40 is mainly configured by an MPU 41, an interface I / F 42, a motor drive circuit 43, and the like. The interface I / F 42 and the motor are mainly connected to the MPU 41 via an input / output bus. A drive circuit 43 and the like are connected. Reference numeral 44 shown in FIG. 1B is a current sensor 44 that can detect a motor current value i that actually flows through the motor 32. Sensor information regarding the motor current value i detected by the current sensor 44 is as follows. The motor current value signal can be input to the MPU 41 via the interface I / F 42.

  The MPU 41 is composed of, for example, a microcomputer, a semiconductor memory device (ROM, RAM, EEPROM, etc.), etc., and has a function of executing control (PI control) of the motor 32 of the transmission ratio variable device 30 by a predetermined computer program. Is.

  The interface I / F 42 receives various inputs from the torque sensor 18 or the current sensor 44 described above in addition to the rotation angle sensor 33 that detects the motor rotation angle θm of the motor 32 and the vehicle speed sensor 26 that detects the vehicle speed V of the vehicle. A function of inputting a sensor signal to a predetermined port of the MPU 41 via an A / D converter or the like is provided.

  The motor drive circuit 43 has a function of converting electric power supplied from a DC power supply (not shown) into controllable three-phase AC power, and includes a PWM circuit and a switching circuit.

  Accordingly, in the ECU 40 shown in FIG. 2, a signal corresponding to the steering angle θs of the torque sensor 18, a signal corresponding to the motor rotation angle θm of the rotation angle sensor 33, and the current sensor 44 by PI control (proportional integral control) described later. The transmission ratio variable device 30 is controlled based on the motor current value i or the signal corresponding to the vehicle speed V of the vehicle speed sensor 26 so that the steering characteristic suitable for the vehicle state can be obtained.

  Next, the calculation process of the PI control system for the motor 32 by the ECU 40 will be described with reference to FIG. This calculation process is performed by, for example, a timer interrupt process executed by the MPU 41 of the ECU 40 at predetermined intervals (for example, 0.2 mSec (millisecond)).

As shown in FIG. 2, ECU 40 includes a ACT angle command unit 51 that outputs the ACT target angle [theta] ta _0, the ACT angle control unit 52 for outputting the ACT control angle [theta] ta ₁ based on the ACT target angle [theta] ta _0, ACT control And a drive signal output unit 53 that outputs a motor drive signal based on the angle θta ₁ .

The ACT angle command unit 51 sets the ACT target angle θta ₀ based on the steering angle θs and the vehicle speed V, and outputs it to the ACT angle control unit 52. Specifically, for example, the ACT angle command unit 51 sets the ACT target angle θta ₀ to be larger than the steering angle θs when the vehicle speed V is low, and when the vehicle speed V is high. Is set so that the ACT target angle θta ₀ is smaller than the steering angle θs.

  The ACT angle control unit 52 includes a proportional control unit 54 as a proportional control unit, an integration control unit 55 as an integral control unit, a gain for setting a proportional gain Kp in the proportional control unit 54 and an integral gain Ki in the integral control unit 55. And a setting unit 56.

When the deviation Δθta between the ACT target angle θta ₀ input from the ACT angle command unit 51 by the subtractor 57 and the motor rotation angle θm detected by the rotation angle sensor 33 is calculated, the proportional control unit 54 calculates the deviation Δθta. By multiplying the proportional gain Kp set by the gain setting unit 56, the proportional control amount εp is calculated. Then, the integral control unit 55 calculates the integral control amount εi by multiplying the integral value of the deviation Δθta by the integral gain Ki set by the gain setting unit 56.
The process of setting the proportional gain Kp and the integral gain Ki in the gain setting unit 56 will be described in detail with reference to the flowcharts shown in FIGS.

The proportional control amount εp calculated by the proportional control unit 54 and the integral control amount εi calculated by the integral control unit 55 are input to the adder 58. The ACT angle control unit 52 calculates the ACT control angle θta ₁ by adding the proportional control amount εp and the integral control amount εi by the adder 58 and outputs the calculated ACT control angle θta ₁ to the drive signal output unit 53.

The drive signal output unit 53 outputs a motor drive signal to the motor drive circuit 43 based on the input ACT control angle θta ₁ , and the motor drive circuit 43 outputs three-phase (U) to the motor 32 based on the motor drive signal. , V, W). The transmission ratio is varied by being driven by the motor 32 and operating the transmission ratio variable device 30 to change the motor rotation angle θm.

  By controlling the motor 32 with the MPU 41, the transmission ratio variable device 30 can be controlled. Here, the process of setting the proportional gain Kp and the integral gain Ki by the gain setting unit 56 described above will be described in detail with reference to the flowcharts shown in FIGS. 3 and 4 and the timing charts shown in FIGS. FIGS. 3 and 4 are flowcharts showing a process of setting the proportional gain Kp and the integral gain Ki in the gain setting unit 56. 5 and 6 are timing charts showing an example in which the proportional gain Kp is gradually decreased when the steering is held, and the integral gain Ki is gradually decreased after the reverse input has elapsed. In particular, FIG. 5 assumes a curb collision. FIG. 6 assumes traveling on uneven roads.

First, in step S101 of FIG. 3, the steering angle θs, the motor rotation angle θm, and the vehicle speed V are acquired. Next, in step S103, the angle change amount | θs−θs ₁ | between the current steering angle θs and the previously detected steering angle θs ₁ is equal to or less than the angle change amount Δθs that is determined to be the steering holding state. It is determined whether or not.

Here, when the driver is steering the steering wheel 12 and the angle change amount | θs−θs ₁ | is not equal to or smaller than Δθs (No in S103), the processing after step S121 described later is performed.

On the other hand, in step S103 described above, FIG. 5 and as a state at time t ₁ or t ₄ in the timing chart of FIG. 6, the driver is not steering the steering wheel 12 angle variation | θs-θs ₁ When | is equal to or smaller than Δθs (Yes in S103), the steering flag Fk is set to 1 in Step S105. Here, the steering flag Fk is a flag that is set to 1 when the steering is maintained (non-steering state), and is set to 0 when the steering is non-steering (steering).

Next, in step S107, processing for starting the counter _{C k} is performed. This counter C _k is activated in this step and then stopped in step S123 described later, so that the time until it is determined No in step S103 until it is determined to be No, that is, the steered state is continued. It is possible to measure the holding duration time tk, which is the measured time.

And in step S109, when the steering continuation time tk is less than the predetermined continuation time tk ₀ and the steering flag Fk is set to 1 soon, it is determined as No and from the above-described step S101. This process is repeated. The duration time tk ₀ is set to 4 s, for example.

Under such a repetition process, when the steering continuation time tk becomes equal to or longer than the continuation time tk ₀ as in the state at time t ₂ or t ₅ in the timing charts of FIGS. 5 and 6 (Yes in S109), in step S111, the vehicle speed shown in Figure 7 - setting process proportional gain reduction DerutaKp ₁ based on the proportional gain reduction amount map is performed.

Specifically, as shown in FIG. 7, if the vehicle speed V is equal to or lower than the first vehicle speed V ₁ that is relatively low, the proportional gain reduction amount ΔKp ₁ = 0 is set. Further, if smaller than the second vehicle speed V ₂ the vehicle speed V is relatively high greater than the first vehicle speed V _1, as the proportional gain reduction DerutaKp ₁ is curved manner toward the zero DerutaKp _m vehicle speed V increases Set to increase. Further, the vehicle speed V is set to be the second speed _{V 2} than the proportional gain reduction ΔKp ₁ = ΔKp _m. In the present embodiment, the first vehicle speed _{V 1} and the second vehicle speed _{V 2,} for example, is set to 10 km / h and 40 km / h. The vehicle speed-proportional gain reduction map is stored in advance in the memory of the MPU 41.

When the proportional gain decrease amount ΔKp ₁ is set in step S111 as described above, the proportional gain Kp is gradually decreased in step S113, and the proportional gain decrease amount ΔKp ₁ is subtracted from the proportional gain Kp.

The gradual reduction process of the proportional gain Kp will be described in detail with reference to the timing charts of FIGS.
When the steering wheel FR, FL of the vehicle collides with a curb or the like while the steering wheel 12 is in the steering state, a large external force (reverse input) that changes the steering angle θt of the steering wheel FR, FL is applied to the steering wheel FR, Input to the steering system via the FL. At this time, since the proportional gain Kp is set to be smaller than the initial proportional gain Kp ₀ which is a preset normal proportional gain Kp by the above-described gradual decrease process of the proportional gain Kp, the steering follow-up by the motor 32 is temporarily performed. As a result, the generation of torque for hindering the change in the turning angle θt of the steered wheels FR and FL can be suppressed. For this reason, a large external force does not act on the steering system such as the differential mechanism 31 disposed between the motor 32 and the steering wheels FR and FL.

In particular, when the vehicle speed V is high, the proportional gain decrease amount ΔKp ₁ increases, and therefore the degree of gradual decrease of the proportional gain Kp increases (see the proportional gain Kp indicated by the one-dot chain line in FIGS. 5 and 6). Thereby, it can change to the state which can suppress generation | occurrence | production of the torque which prevents the above steering angle changes.

On the other hand, when the vehicle speed V is low, the proportional gain decrease amount ΔKp ₁ becomes small, so that the degree of gradual decrease of the proportional gain Kp becomes small (see the proportional gain Kp indicated by the two-dot chain line in FIGS. 5 and 6). Thereby, even if it is a case where the proportional gain Kp is decreased at the time of a steering hold state, the steering follow-up property by the motor 32 can be quickly returned if it becomes a non-steering state (steering state).

Next, in step S115, when the proportional gain Kp that has been gradually reduced in step S113 becomes less than 1/3 of the initial proportional gain Kp ₀ (No in S115), the proportional gain Kp is initialized in step S117. It is set to be equal to 1/3 of the proportional gain Kp _0. By this, the proportional gain Kp is set so as not to less than one third of the initial proportional gain Kp _0.

On the other hand, as the state at time t ₃ in the timing chart of FIG. 5 and 6, consists of the holding steering state (non-steering state) to the non-steering holding state (steering state), and No in step S103 described above determines Then, the steering flag Fk is set to 0 in step S121. Then, in step S123, processing for stopping the counter _{C k} that started in the step S107 is performed.

Then, in step S125, (Yes in S125) and the proportional gain Kp is set to less than the initial proportional gain Kp ₀ by gradual reduction process in the step S113, and adds the proportional gain Kp by the proportional gain increment DerutaKp ₂ in step S127 Increase gradually. Here, DerutaKp _2, for example, is set to be equal to DerutaKp _m described above. Further, when the proportional gain Kp is set to be equal to or higher than the initial proportional gain Kp ₀ by the proportional gain gradually increasing process (No in S125), the proportional gain Kp is set to be equal to the initial proportional gain Kp ₀ in step S129. Is done. After the process of step S127 or S129, the process after step S151 of FIG. 4 mentioned later is made.

3 is performed, the motor rotational angular velocity ω obtained by differentiating the motor rotational angle θm in step S131 of FIG. 4 is transmitted to the steering system via the steering wheels FR and FL. It is determined whether or not the rotational angular velocity ω ₀ is determined to be abruptly rotated due to the large reverse input.

If no reverse input is input and the motor rotational angular velocity ω is less than the rotational angular velocity ω ₀ (No in S131), it is determined in step S133 whether the reverse input flag Fr is 1 or not. Here, the reverse input flag Fr is set to 1 when the predetermined duration time tr ₀ has not elapsed since the reverse input was input to the steering system via the steering wheels FR and FL, and the reverse input is input. This is a flag that is not set or is set to 0 when the duration tr ₀ has elapsed since it was input. At this stage, since the reverse input flag Fr is not set to 1 (No in S133), the processing after Step S151 described later is performed.

Here, when the motor rotation angular velocity ω increases in accordance with the steering of the steering wheel 12, since it is in the non-steering state (steering state), it is determined No in step S103 in FIG. The process in S131 is not performed. For this reason, when it is determined in step S131 that the motor rotational angular velocity ω is equal to or higher than the rotational angular velocity ω _0, it can be determined that the reverse input is input from the steering wheels FR and FL to the steering system.

In step S131 described above, as the state at time t ₆ of the timing chart of FIG. 5 and 6, the motor rotation angular speed ω is by large reverse input is inputted to the steering system through a steering wheel FR, FL It becomes the rotational angular velocity omega ₀ or more (Yes in S131), together with the reverse input flag Fr is set to 1 in step S135, in step S137, processing for stopping the counter _{C r} to be described later is made.

Then, in step S139, processing for starting the counter _{C r} is performed. This counter _Cr is activated by this step, and then stopped by step S137 or step S153, which will be described later, in the same manner as the counter C _k described above, so that the time from when Yes is determined in step S131, That is, the reverse input elapsed time tr, which is the elapsed time since the reverse input was input to the steering system, can be measured.

In step S141, if the reverse input elapsed time tr is less than the predetermined duration tr ₀ and the reverse input flag Fr is set to 1 soon, it is determined No, and in step S143, the integration is performed. The gain Ki is gradually reduced, and the integral gain decrease amount ΔKi ₁ is subtracted from the integral gain Ki. The duration time tr ₀ is set to 1 s, for example.

In step S145, when the integral gain Ki that has been gradually reduced in step S143 becomes less than 1/3 of the initial integral gain Ki ₀ that is a preset normal integral gain Ki value (S145). in No), the integral gain Ki is set to be equal to 1/3 of the initial integration gain Ki ₀ at step S147. By this, the integral gain Ki is set so as not to less than 1/3 of the initial integration gain Ki _0.

In step S131 described above, when the reverse input is input to the steering system for a while, the motor rotation angular velocity ω becomes less than the rotation angular velocity ω ₀ and it is determined No. At this stage, since the state where the reverse input flag Fr is set to 1 in step S135 is continued, it is determined Yes in step S133, and the processing from step S139 described above is performed.

Here, in step S141 described above, as the state at time t ₇ in the timing chart of FIG. 5 and FIG. 6, when the reverse input elapsed time tr reaches a predetermined duration tr ₀ or more, Yes is determined in step The process after S151 is performed.

When any one of the above-described processes in steps S127 and S129, the determination process with No in step S133, and the determination process with Yes in step S141 is performed, the reverse input flag Fr is set to 0 in step S151. At the same time, in step S153, a process of stopping the counter C _k started in step S139 is performed.

Then, in step S155, the integral gain Ki is (Yes in S155) initial integration gain Ki ₀ than to that set by the gradual decrease process in step S143, the integral gain increment DerutaKi ₂ only adds to the integral gain Ki in step S157 Increase gradually. In addition, when the integral gain Ki is set to be equal to or greater than the initial integral gain Ki ₀ by such integral gain gradually increasing processing (No in S155), the integral gain Ki is set to be equal to the initial integral gain Ki ₀ in step S159. Is done.

Here, the process of gradually decreasing the integral gain Ki will be described in detail with reference to the timing charts of FIGS.
As shown in FIG. 5, in the state where the proportional gain Kp is gradually reduced because the steering is maintained, a reverse input is input to collide with a curbstone and steer the steered wheels FR and FL in the return direction. When the motor rotational angular velocity ω becomes equal to or higher than the rotational angular velocity ω ₀ and the turning angle θt approaches the straight traveling state 0 (time t ₆ shown in FIG. 5), the integral gain Ki decreases and the motor current value i decreases. .

At this time, the motor current value i increases when the integral gain Ki becomes constant at 1/3 of the initial integral gain Ki _0. However, since the integral gain Ki is decreased, the motor current value i does not increase rapidly. Absent. Since the proportional follow-up gain Kp and the integral gain Ki are reduced, the steering followability by the motor 32 is lowered. Therefore, the steering angle θs does not change so much, and the reverse input is a large external force between the motor and the steered wheels. It does not act on the steering system arranged between them. When the reverse input elapsed time tr exceeds the predetermined duration tr ₀ and the reverse input does not affect the steering system (time t ₇ shown in FIG. 5), the integral gain Ki is increased to the initial integral gain Ki _0. Thus, the steering tracking performance by the motor is recovered.

Further, as shown in FIG. 6, in the state where the proportional gain Kp is gradually reduced because the steering state is maintained, the steering wheels FR and FL are turned in the turning direction or the turning back direction by running on the uneven road. When reverse inputs are sequentially input and the motor rotational angular velocity ω becomes equal to or greater than the rotational angular velocity ω ₀ and the turning angle θt changes abruptly (time t ₆ , t ₈ , t ₉ , t ₁₀ shown in FIG. 6), the integral gain Ki Decrease.

In this way, when reverse inputs for turning in the increasing direction or the returning direction are sequentially input, a new reverse input is input before the reverse input elapsed time tr becomes equal to or longer than the predetermined duration tr _0. (Times t ₉ and t ₁₀ shown in FIG. 6). Therefore, after the processing for stopping the counter C _k that started in step S139 it is made in step S137, again, in step S139, the counter C _r the start process is performed inverse input elapsed time tr 0 Is set.

At this time, when the integral gain Ki becomes constant at 1/3 of the initial integral gain Ki ₀ and the deviation Δθta is integrated and the integral value increases, the motor current value i increases, but the integral gain Ki is decreased. Therefore, the motor current value i does not increase rapidly. Since the proportional follow-up gain Kp and the integral gain Ki are reduced, the steering followability by the motor 32 is lowered. Therefore, the steering angle θs does not change so much, and the reverse input is a large external force between the motor and the steered wheels. It does not act on the steering system arranged between them. When the reverse input elapsed time tr becomes equal to or longer than the predetermined duration tr ₀ and the reverse input does not affect the steering system (time t ₁₁ shown in FIG. 6), the integral gain Ki is increased to the initial integral gain Ki _0. Thus, the steering tracking performance by the motor is recovered.

As described above, in the transmission ratio variable device 30 according to the present embodiment, the ECU 40 causes the deviation Δθta between the ACT target angle θta ₀ that is a target steering angle set according to the vehicle speed V of the vehicle and the motor rotation angle θm. The rotational drive of the motor 32 is controlled on the basis of a proportional control amount εp obtained by multiplying by a proportional gain Kp. At this time, if the gain setting unit 56 determines that the steering state of the steering wheel 12 continues for a certain period of time based on the steering angle θs, the ECU 40 specifically determines the amount of change in the steering angle | When the state where θs−θs ₁ | is equal to or less than the angle change amount Δθs determined to be in the steering holding state is continued for a certain period of time, the proportional gain Kp is gradually decreased.

As a result, when the steering wheel 12 is in the steering holding state, a large reverse input such that the turning angle θt of the steering wheels FR, FL changes when the steering wheels FR, FL of the vehicle collide with a curbstone or the like is applied to the steering wheel FR. even when it is input via the FL, become temporarily the steering follow-up performance of the motor 32 is reduced to have less than the initial proportional gain Kp ₀ the proportional gain Kp is a normal value Further, it is possible to suppress the generation of torque for hindering the change in the turning angle θt of the steered wheels FR and FL. For this reason, a large external force does not act on the steering system such as the differential mechanism 31 disposed between the motor 32 and the steering wheels FR and FL.
Accordingly, it is possible to suppress the influence on the steering system due to the external force input via the steering wheels FR and FL.

In the variable transmission ratio device 30 according to the present embodiment, the ECU 40 causes the gain setting unit 56 to increase the proportional gain reduction amount ΔKp ₁ as the vehicle speed V of the vehicle increases. In general, when the vehicle speed V is low, the steering frequency is higher than when the vehicle speed V is high. Therefore, when the steering frequency is low, that is, when the vehicle speed V is high, the proportional gain decrease amount ΔKp ₁ is increased to quickly reach a state where the generation of torque that hinders the change in the steering angle as described above can be suppressed. Can be migrated to. On the other hand, when the steering frequency is high, that is, when the vehicle speed V is low, the proportional gain decrease amount ΔKp ₁ is reduced to reduce the proportional gain Kp during the steered state, even in the non-steered state. When (steering state) is reached, the steering followability by the motor 32 can be quickly restored.

Further, in the transmission ratio variable device 30 according to the present embodiment, the ECU 40 controls the integral control amount εi obtained by multiplying the integral value of the deviation Δθta between the ACT target angle θta ₀ and the motor rotation angle θm by the integral gain Ki and the proportional control described above. The rotational drive of the motor 32 is controlled based on the amount εp. At this time, when the gain setting unit 56 determines that the steered state of the steering wheel 12 has continued for a certain period of time based on the steering angle θs, the ECU 40 receives the reverse input via the steered wheels FR and FL. When the input is made to the steering system, the integral gain Ki is decreased while the reverse input affects the steering system, specifically, until the reverse input elapsed time tr elapses the duration tr ₀ . .

Thus, when the reverse input is input to the steering system via the steered wheels FR and FL when the steering wheel 12 is in the steering-holding state, the integral gain Ki decreases, so the steering of the motor 32 that has been reduced by the decrease of the proportional gain Kp. Followability can be further reduced. When the reverse input elapsed time tr elapses the duration tr ₀ and the reverse input does not affect the steering system, the integral gain Ki is an initial integral gain Ki ₀ that is a normal integral gain Ki that is preset. As a result, the steering followability by the motor 32 can be recovered.

The present invention is not limited to the above embodiments, and may be embodied as follows. Even in this case, the same operations and effects as those of the above embodiments can be obtained.
(1) the vehicle speed shown in Figure 7 - in the proportional gain reduction map, if the vehicle speed V is smaller than the second vehicle speed V ₂ greater than the first vehicle speed V _1, the proportional gain reduction DerutaKp ₁ as the vehicle speed V is increased 0 from not limited to be set to curvedly increases toward the DerutaKp _m, for example, it may be configured to linearly increase as the vehicle speed V increases.

(2) In the gradual reduction process of the proportional gain Kp, the process is not limited to setting the proportional gain Kp to be less than 1/3 of the initial proportional gain Kp ₀ as in the processes in steps S115 and S117. You may set so that it may not become less than this reference value on the basis of a different value.
Further, in the gradual reduction process of the integral gain Ki, the integral gain Ki is not limited to be set to be less than 1/3 of the initial integral gain Ki ₀ as in the processes in steps S145 and S147, and is different from 1/3. You may set so that it may not become less than this reference value on the basis of a value.

FIG. 1A is an explanatory diagram showing a schematic configuration of a vehicle control device to which a transmission ratio variable device according to an embodiment of the present invention is applied, and FIG. 1B is a circuit showing a configuration example of an ECU or the like. It is a block diagram. It is a functional block diagram regarding the PI control system of the motor which concerns on this embodiment. It is a part of flowchart which shows the process which sets the proportional gain and integral gain in a gain setting part. It is a part of flowchart which shows the process which sets the proportional gain and integral gain in a gain setting part. 6 is a timing chart showing an example of gradually increasing the proportional gain when the steering is held and gradually increasing the integral gain after the reverse input has elapsed. 6 is a timing chart showing an example of gradually increasing the proportional gain when the steering is held and gradually increasing the integral gain after the reverse input has elapsed. It is explanatory drawing which shows an example of the vehicle speed-proportional gain reduction amount map used for the proportional gain reduction amount setting process of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Vehicle control apparatus 14 ... 1st steering shaft (input shaft, steering system)
16 ... Second steering shaft (output shaft, steering system)
18 ... Torque sensor (steering angle acquisition means)
26 ... Vehicle speed sensor (vehicle speed detection means)
30 ... Transmission ratio variable device 31 ... Differential mechanism (Transmission ratio variable mechanism)
32 ... Motor 40 ... ECU (motor control means)
DESCRIPTION OF SYMBOLS 51 ... ACT angle command part 52 ... ACT angle control part 54 ... Proportional control part 55 ... Integration control part 56 ... Gain setting part (gain setting means)
Ki ... Integral gain Ki ₀ ... Initial integral gain Kp ... Proportional gain Kp ₀ ... Initial proportional gain V ... Vehicle speed ΔKi ₁ … Integral gain decrease ΔKi ₂ … Integral gain increase ΔKp ₁ … Proportional gain decrease ΔKp ₂ … Proportional gain increase Amount Δθta ... deviation εi ... integral control amount εp ... proportional control amount θm ... motor rotation angle θs ... steering angle θt ... steering angle θta ₀ ... ACT target angle (target steering angle)
θta ₁ ... ACT control angle

Claims (3)

Provided in the middle of the steering system of the vehicle connecting the steering wheel and the steering wheel,
A transmission ratio variable mechanism capable of changing a transmission ratio between the input shaft on the steering wheel side and the output shaft on the steering wheel side by rotating the motor;
Steering angle detecting means for detecting the steering angle of the input shaft;
Vehicle speed detecting means for detecting the vehicle speed of the vehicle;
Rotation angle detection means for detecting the rotation angle of the motor;
Motor control means for controlling the rotational drive of the motor based on a proportional control amount obtained by multiplying a deviation between the target steering angle and the rotation angle set according to the vehicle speed by a proportional gain;
A transmission ratio variable device comprising:
The motor control means includes gain setting means for reducing and setting the proportional gain when it is determined that the steering wheel holding state has continued for a predetermined time based on the steering angle. A variable transmission ratio device.   2. The variable transmission ratio device according to claim 1, wherein the gain setting means increases the decrease amount of the proportional gain as the vehicle speed increases. The motor control means controls the rotational drive of the motor based on the integral control amount obtained by multiplying the deviation between the target steering angle and the rotation angle by an integral gain and the proportional control amount,
If the external force is input to the steering system via the steered wheels when it is determined based on the steering angle that the steered state of the steering wheel continues for a certain time, the gain setting means The transmission ratio variable device according to claim 1 or 2, wherein the integral gain is decreased and set while the torque affects the steering system.

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