JPH11255140A - Vehicle steering control device - Google Patents

Abstract

(57) [Problem] To provide a vehicle steering control device capable of improving the steering responsiveness of a vehicle by changing a response characteristic of the vehicle in accordance with a change of a motion characteristic of the vehicle. Kind Code: A1 Abstract: A motion characteristic varying means for changing a motion characteristic of a vehicle, a steering handle and a steered wheel 24FR.
24FL, which is provided in the middle of the steering transmission system connecting the steering wheel 24FL and the steering wheels 24FR and 24FR.
A variable gear ratio unit 14 that varies the transmission ratio of the FL to the steering amount based on the motion characteristics of the vehicle is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering control device for a vehicle.

[0002]

2. Description of the Related Art As a conventional vehicle steering control device, a steering shaft is divided into an upper shaft and a lower shaft as described in Japanese Utility Model Application Laid-Open No. 51180/1985, and the steering shaft is controlled according to the load weight of the vehicle. It is known to connect the respective shafts directly or indirectly via a torsion bar. This device reduces the torsional rigidity of the steering shaft when the weight of the vehicle is large, makes the gear ratio of the steering moderately large and enables a smooth steering operation, and when the weight of the vehicle is small, the steering shaft The aim is to increase the torsional rigidity to enable a sharp steering operation.

[0003]

However, since this device changes the responsiveness of the vehicle by changing the steering gear ratio in accordance with the load weight, when the kinetic characteristics of the vehicle change, the device does not necessarily change. The response characteristics and the movement characteristics do not always match. Therefore, when the vehicle is steered, the driver may feel uncomfortable.

The present invention has been made in view of such a problem, and an object of the present invention is to provide a vehicle steering control device capable of obtaining a response characteristic of a vehicle in accordance with a change in a vehicle dynamic characteristic. I do.

[0005]

In order to achieve the above object, a steering control device for a vehicle according to the present invention is provided in a steering transmission system connecting a steering wheel and a steered wheel. Transmission ratio variable means for varying the transmission ratio between the steering amount and the steered amount of the steered wheels, motion characteristic variable means for changing the vehicle dynamics, and transmission to the transmission ratio variable means in response to the change in the vehicle dynamics Changing means for changing the ratio.

[0006] A vehicle steering control device according to the present invention comprises:
The above-mentioned motion characteristic varying means is a vehicle height varying means for changing the height of the vehicle.

[0007] A vehicle steering control device according to the present invention includes:
The dynamic characteristic varying means is a damping force characteristic varying means for changing a damping force characteristic of a vehicle suspension.

According to these inventions, when the motion characteristics of the vehicle are changed, the transmission ratio is set in accordance with the changed motion characteristics, so that the optimum vehicle response according to the motion characteristics of the vehicle is achieved. Characteristics are obtained. Therefore, the driver can operate the vehicle without feeling uncomfortable.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings, the same elements are denoted by the same reference numerals, and the description is omitted. Also, the dimensional ratios in the drawings do not always match those described.

(First Embodiment) FIG. 1 is a schematic diagram showing the configuration of a vehicle steering control device 2 according to this embodiment. As shown in FIG. 1, an upper end of an upper steering shaft 12a is connected to the steering handle 10, and a variable gear ratio unit 14 is connected to a lower end of the upper steering shaft 12a.
Input side is connected. The upper end of the lower steering shaft 12b is connected to the output side of the variable gear ratio unit 14. For this reason, the steering handle 10
The steering force given to the upper steering shaft 12
a and transmitted to the lower steering shaft 12b via the variable gear ratio unit 14.

A pinion (not shown) is provided at a lower end of the lower steering shaft 12b, and the pinion is engaged with a rack bar 18 in the steering gear box 16. Furthermore, one end of a tie rod 20 is connected to each end of the rack bar 18, and steered wheels (front wheels) 24 FL and 24 FR are connected to the other end of each tie rod 20 via a knuckle arm 22.

A steering angle sensor 26 for detecting a steering angle θ _H of the steering handle 10 is provided on the upper steering shaft 12a, and a steering angle (pinion angle) θ _P of the steered wheels 24 is detected on the lower steering shaft 12b. An output angle sensor 28 is provided. This steering angle sensor 26
The steering angle of the steering wheel 10 and the pinion angle detected by the output angle sensor 28 are input to an electronic control unit (ECU) 30.

The variable gear ratio unit 14 changes the transmission ratio between the amount of steering of the steering wheel 10 and the amount of steering of the steered wheels 24FL and 24FR, and includes a motor (not shown), a planetary gear mechanism or a harmonic. And a speed reducer (not shown) using a drive mechanism or the like. The variable gear ratio unit 14 is connected to the ECU 30 via a motor driver 36, and operates by receiving a control signal from the ECU 30.

The steered wheels (front wheels) 24FL, 24FR and the non-steered wheels (rear wheels) 24RL, 24RR are provided with air springs 32FL, 32FR, 32RL, 32RR. Air spring 32FL, 32FR, 32RL,
32RR is one component of the air suspension of the vehicle, and functions as a vehicle height varying unit that varies the height of the vehicle body with respect to the road surface according to the state of air injection. Each of the air springs 32FL, 32FR, 32RL, and 32RR is connected to a compressor (not shown) through a pipe, and has a structure in which air can be supplied.

Compressor and each air spring 32F
L, 32FR, 32RL, and 32RR, the solenoid valves 34FL, 34FR, 34RL, and 3
4RR is provided. Solenoid valves 34FL, 34FR,
34RL and 34RR are valves that open and close in response to a signal from the ECU 30.
The state of air injection into FL, 32FR, 32RL, and 32RR is adjusted. The height of the vehicle body is controlled by adjusting the air injection and the like.

The vehicle is provided with a vehicle height adjustment switch 44. The vehicle height adjustment switch 44 is a switch for adjusting the height of the vehicle body, and is operated by the driver. The vehicle height adjustment switch 44 functions as a movement characteristic varying unit that changes the movement characteristics of the vehicle by adjusting the height of the vehicle body. The vehicle height adjustment switch 44
Is connected to the ECU 30 so that the ECU 30 can detect the presence or absence of the switch operation.

A vehicle speed sensor 38 is connected to the ECU 30, and a signal of the running speed of the vehicle detected by the vehicle speed sensor 38, that is, a signal of the vehicle speed V is input to the ECU 30.

Next, the operation of the vehicle steering control device 2 will be described.

FIG. 2 shows a flowchart of the operation of the vehicle steering control device 2. First, as shown in step S10 of FIG. 2, the vehicle speed V output from the vehicle speed sensor 38, the steering angle θ _H output from the steering angle sensor 26, the output angle sensor 28
The steering angle θ _P output from the controller is read. Then, the calculation of the transmission ratio G (V) is performed based on the vehicle speed V.
(Step S12). The calculation of the transmission ratio G (V) is performed, for example, by referring to a map of the transmission ratio G (V) with respect to the vehicle speed V preset in the ECU 30 as shown in FIG. 3 (solid line).

Then, the output of the vehicle height adjustment switch 44 is read (step S14). Next, whether or not the vehicle height adjustment switch 44 has been operated is determined based on the result of the reading (step S16). If it is determined that the vehicle height adjustment switch 44 has not been operated, the process proceeds to step S20. On the other hand, when it is determined that the vehicle height adjustment switch 44 is operated, the process proceeds to step S18, and the setting of the transmission ratio is changed according to the change of the vehicle height.

That is, as shown in the following expression (1), the transmission ratio G is calculated by multiplying the transmission ratio G (V) obtained by the calculation based on the vehicle speed V by the coefficient K1 corresponding to the vehicle height adjustment. You.

G = K1 · G (V) ‥‥ (1) In this case, for example, when the vehicle height is adjusted to be higher by operating the vehicle height adjustment switch 44, the coefficient K1 is set to a numerical value of 1 or more. As shown by the broken line in FIG. 3, the transmission ratio G is set to be larger than before the operation of the vehicle height adjustment switch 44.

In step S20 of FIG. 2, the transmission ratio G (V) obtained in step S12 or step S1
The target steering angle θ _P1 is calculated based on the transmission ratio G obtained in Step 8. That is, the target turning angle θ _P1 is _calculated by the following equation (2).
As shown in, and calculated by the obtained transmission ratio G or transmission ratio G (V), it is calculated by multiplying the steering angle theta _H read.

Θ _P1 = G (V) · θ _H ‥‥ (2) A control signal is output from the ECU 30 to the variable gear ratio unit 14 (step S22), and based on the control signal, the control signals of the steered wheels 24FL and 24FR are output. The variable gear ratio unit 14 operates such that the turning angle θ _P becomes the target turning angle θ _P1 .

On the other hand, the ECU 30 sends the electromagnetic valves 34FL, 3FL
An operation signal is output to each of 4FR, 34RL, and 34RR (step S24). The solenoid valves 34FL, 34FR, 34RL, 34RR are operated according to the operation signals, and the respective air springs 32FL, 32F installed on the wheels 24FL, 24FR, 24RL, 24RR.
Air is supplied to R, 32RL, and 32RR. The vehicle height is adjusted based on the air injection state.

As described above, according to the vehicle steering control device 2 of the present embodiment, when the vehicle height is adjusted by the driver and the vehicle dynamics characteristics are changed, the changed vehicle dynamics characteristics are changed. The transmission ratio is set correspondingly. Therefore, an optimum vehicle response characteristic according to the vehicle motion characteristic can be obtained.
Therefore, the driver can operate the vehicle without feeling uncomfortable.

Further, when the vehicle height is adjusted to be high, the transmission ratio becomes large, and abrupt movement of the vehicle body is suppressed, so that the riding comfort of the vehicle can be improved.

In the vehicle steering control device 2 according to the present embodiment, when the vehicle height is adjusted to be low by operating the vehicle height adjustment switch 44, the transmission ratio G is set to a value of 1 or less. May be set smaller than before the operation of the vehicle height adjustment switch 44. In this case, since the vehicle height is reduced and the transmission ratio is reduced, good vehicle responsiveness can be obtained.

If the vehicle height adjustment can be set in three or more stages by operating the vehicle height adjustment switch 44, the coefficient K1 may be set and the transmission ratio G may be changed accordingly.

Further, in the vehicle steering control device 2 according to the present embodiment, a vehicle height sensor is provided in the vehicle, and the air injection state of the air spring 32 is feedback-controlled based on the output of the vehicle height sensor. Good.

(Second Embodiment) Next, a vehicle steering control device 2a according to a second embodiment will be described.

The vehicle steering control device 2a according to the present embodiment.
Has substantially the same structure as the vehicle steering control device 2 according to the first embodiment shown in FIG. However, a plurality of maps for calculating the transmission ratio based on the vehicle speed V are set in advance in the ECU 30 as shown in FIGS.
In order to calculate the transmission ratio in accordance with the change in the motion characteristics of the vehicle, the map can be appropriately switched and used.

Next, the operation of the vehicle steering control device 2a according to this embodiment will be described.

FIG. 6 is a flowchart showing the operation of the vehicle steering control device 2a according to this embodiment. First, FIG.
As shown in step S30, the vehicle speed V output from the vehicle speed sensor 38, the steering angle θ _H output from the steering angle sensor 26, and the steering angle θ _P output from the output angle sensor 28 are read. Next, the output of the vehicle height adjustment switch 44 is read (step S32). Then, it is determined whether or not the vehicle height adjustment switch 44 has been operated based on the result of the reading (step S34). When it is determined in step S34 that the vehicle height adjustment switch 44 has not been operated, the process proceeds to step S36, and the transmission ratio G1 (V) is calculated based on the vehicle speed V according to the map I shown in FIG. That is, when the vehicle speed V is low, the transmission ratio G1 (V) is set small, and when the vehicle speed V is high, the transmission ratio G1 (V) is set large.

On the other hand, when it is determined in step S34 that the vehicle height adjustment switch 44 has been operated, the process proceeds to step S38, and the transmission ratio is determined based on the vehicle speed V according to the map II shown in FIG. G2 (V) is calculated. The transmission ratio G2 (V) of the map II shown in FIG. 5 is set higher in each vehicle speed region than the transmission ratio G1 (V) of the map I (solid line in FIG. 5), and the vehicle height adjustment is performed. By operating the switch 44, the transmission ratio is set high.

Then, in step S40, step S
Based on the transmission ratio G1 (V) obtained in step S36 or the transmission ratio G2 (V) obtained in step S38, the target turning angle θ _P1
Is calculated. That is, the above equation (2) (θ _P1 = G
As shown in (V) · θ _H ), the target turning angle θ _P1 is obtained by multiplying the transmission ratio G (the transmission ratio G1 (V) or the transmission ratio G2 (V)) by the read steering angle θ _H. Is calculated by

Then, a control signal is output from the ECU 30 to the variable gear ratio unit 14 (step S42), and based on the control signal, the steered angle θ _P of the steered wheels 24FL and 24FR becomes the target steered angle θ _P1. Then, the variable gear ratio unit 14 operates.

On the other hand, the ECU 30 sends the solenoid valves 34FL, 3FL
An operation signal is output to each of 4FR, 34RL, and 34RR (step S44). The solenoid valves 34FL, 34FR, 34RL, 34RR are operated according to the operation signals, and the respective air springs 32FL, 32F installed on the wheels 24FL, 24FR, 24RL, 24RR.
Air is supplied to R, 32RL, and 32RR. The vehicle height is adjusted based on the air injection state.

As described above, even in the vehicle steering control device 2a according to the present embodiment, the vehicle height is adjusted by the driver in the same manner as the vehicle steering control device 2 according to the first embodiment. When the motion characteristics of the vehicle are changed, the transmission ratio is set according to the changed motion characteristics. Therefore, an optimum vehicle response characteristic according to the vehicle motion characteristic can be obtained. Therefore, the driver can operate the vehicle without feeling uncomfortable.

Further, when the vehicle height is adjusted to be high, the transmission ratio becomes large, so that the abrupt movement of the vehicle body is suppressed and the riding comfort of the vehicle can be improved.

In the vehicle steering control device 2a according to the present embodiment, when the vehicle height is adjusted to be low by operating the vehicle height adjustment switch 44, the vehicle speed-transmission ratio in which the value of the transmission ratio becomes smaller in each vehicle speed region. By using a characteristic map, the transmission ratio G may be set smaller than before the operation of the vehicle height adjustment switch 44. In this case, since the vehicle height is adjusted to be low and the transmission ratio becomes small, good vehicle responsiveness can be obtained.

If the vehicle height adjustment can be set in three or more stages by operating the vehicle height adjustment switch 44, the transmission ratio G is determined by using a map of the vehicle speed-transmission ratio characteristic adapted to the three stages.
May be changed.

Further, in the vehicle steering control device 2a according to this embodiment, a vehicle height sensor is provided in the vehicle, and the air injection state of the air spring 32 is feedback-controlled based on the output of the vehicle height sensor. Good.

(Third Embodiment) Next, a vehicle steering control device 2b according to a third embodiment will be described.

FIG. 7 is a schematic diagram showing the configuration of a vehicle steering control device 2b according to this embodiment. As shown in FIG.
4FL, 24FR, 24RL, 24RR are provided with shock absorbers 42FL, 42FR, 42RL, 42RR, respectively. Shock absorber 42F
L, 42FR, 42RL, and 42RR are components of the suspension of the vehicle, which attenuate the vibration of the spring, and have a variable damping force characteristic type. Each shock absorber 42FL, 42FR,
42RL and 42RR are connected to the ECU 30,
Upon receiving a control signal from the ECU 30, the damping force characteristic can be adjusted according to the control signal, and functions as damping force characteristic varying means in the vehicle steering control device 2b.

The vehicle is provided with a suspension adjustment switch 46. The suspension adjustment switch 46 is connected to each shock absorber 42 of the suspension.
The switch is operated when adjusting the damping force characteristic of the vehicle, and is operated by the driver. The suspension adjustment switch 46 functions as a dynamic characteristic varying unit that varies the dynamic characteristic of the vehicle by adjusting the damping force characteristic of each shock absorber 42. The suspension adjustment switch 46 is connected to the ECU 30,
The ECU 30 can detect the presence or absence of the switch operation.

Next, the operation of the vehicle steering control device 2b according to this embodiment will be described.

The vehicle steering control device 2b according to this embodiment
Is performed based on the above-described flowchart of FIG. First, as shown in step S10 of FIG. 2, reading of the vehicle speed V output from the vehicle speed sensor 38, the steering angle θ _H output from the steering angle sensor 26, and the steering angle θ _P output from the output angle sensor 28. Is performed. Then, the transmission ratio G (V) is calculated based on the vehicle speed V (step S).
12). The calculation of the transmission ratio G (V) is performed, for example, as shown by a solid line in FIG.
By referring to a map of the transmission ratio G (V) with respect to.

Then, the suspension adjustment switch 46
Is read (step S14). Next, it is determined whether or not the suspension adjustment switch 46 has been operated based on the result of the reading (step S).
16). When it is determined that the suspension adjustment switch 46 has not been operated, the process proceeds to step S20. On the other hand, when it is determined that the suspension adjustment switch 46 has been operated, the process proceeds to step S18, and the setting of the transmission ratio is changed according to the change of the suspension characteristics.

That is, the above equation (1) (G = K1 · G
As shown in (V)), the transmission ratio G is calculated by multiplying the transmission ratio G (V) obtained by the calculation based on the vehicle speed V by the coefficient K1 according to the suspension adjustment. In this case, for example, when the suspension characteristic is softly adjusted by operating the suspension adjustment switch 46, the coefficient K1 is set to a numerical value of 1 or more, so that the transmission ratio G is set to the value of the suspension adjustment switch 46 as shown in FIG. It is set larger than before operation.

Then, the process proceeds to step S20, in which the transmission ratio G (V) obtained in step S12 or step S1 is obtained.
The target turning angle θ _P1 is calculated based on the transmission ratio G obtained in Step 8. That is, the target turning angle θ _P1 is calculated by the transmission ratio G or the transmission ratio G (V) obtained by the calculation as shown in the above equation (2) (θ _P1 = G (V) · θ _H ). It is calculated by multiplying the steering angle theta _H read.

Then, a control signal is output from the ECU 30 to the variable gear ratio unit 14 (step S22), and based on the control signal, the steered angle θ _P of the steered wheels 24FL, 24FR becomes the target steered angle θ _P1. Then, the variable gear ratio unit 14 operates.

On the other hand, an operation signal is output from the ECU 30 to each of the shock absorbers 42 (step S2).
4). According to the operation signal, each shock absorber 42
Is adjusted so as to reduce the damping force.

As described above, according to the vehicle steering control device 2b according to the present embodiment, when the characteristics of the suspension are adjusted by the driver and the dynamic characteristics of the vehicle are changed, the changed dynamic characteristics are changed. The transmission ratio is set in accordance with. Therefore, an optimum vehicle response characteristic according to the vehicle motion characteristic can be obtained. Therefore, the driver can operate the vehicle without feeling uncomfortable.

Further, when the characteristics of the suspension are adjusted softly, the transmission ratio increases, and abrupt movement of the vehicle body is suppressed, so that the riding comfort of the vehicle can be improved.

In the vehicle steering control device 2b according to the present embodiment, when the suspension characteristics are hardly adjusted by operating the suspension adjustment switch 46, the coefficient K1 is set to a numerical value of 1 or less, so that the transmission ratio is reduced. G may be set smaller than before the suspension adjustment switch 46 is operated. In this case, since the suspension characteristics are hardened and the transmission ratio is reduced, good responsiveness of the vehicle can be obtained.

If the suspension adjustment can be set in three or more stages by operating the suspension adjustment switch 46, the coefficient K1 may be set and the transmission ratio G may be changed accordingly.

(Fourth Embodiment) Next, a vehicle steering control device 2c according to a fourth embodiment will be described.

The vehicle steering control device 2c according to the present embodiment.
Has substantially the same structure as the vehicle steering control device 2b according to the third embodiment shown in FIG. However, the ECU 30
In FIG. 4, a plurality of maps for calculating the transmission ratio based on the vehicle speed V are set in advance as shown in FIGS. 4 and 5, and in order to calculate the transmission ratio in accordance with the change in the motion characteristics of the vehicle. The map can be switched and used as appropriate.

The vehicle steering control device 2c according to the present embodiment.
Operates based on the flowchart shown in FIG. That is, as shown in step S30 in FIG. 6, the vehicle speed V output from the vehicle speed sensor 38, the steering angle θ _H output from the steering angle sensor 26, and the steering angle θ _P output from the output angle sensor 28 are read. It is. Next, the output of the suspension adjustment switch 46 is read (Step S).
32). Then, it is determined whether or not the suspension adjustment switch 46 has been operated based on the result of the reading (step S34). When it is determined in step S34 that the suspension adjustment switch 46 has not been operated, the process proceeds to step S36, and the transmission ratio G1 (V) is calculated based on the vehicle speed V according to the map I shown in FIG.

On the other hand, when it is determined in step S34 that the suspension adjustment switch 46 has been operated, the flow shifts to step S38, where the map shown in FIG.
According to the map II shown in FIG.
(V) is calculated. Transmission ratio G of map II shown in FIG.
2 (V), the transmission ratio is set higher in each vehicle speed region than the transmission ratio G1 (V) of the map I, and the transmission ratio is set higher by operating the suspension adjustment switch 46.

Then, the flow shifts to step S40, in which the transmission ratio G1 (V) obtained in step S36 or step S40 is obtained.
The target steering angle θ _P1 is calculated based on the transmission ratio G2 (V) obtained at 38. That is, the above equation (2) (θ
_P1 = G (V) · θ _H ), the target turning angle θ
_P1 is the transmission ratio G (transmission ratio G1 (V) or transmission ratio G2
(V)) is multiplied by the read steering angle θ _H.

Then, a control signal is output from the ECU 30 to the variable gear ratio unit 14 (step S42), and based on the control signal, the turning angle θ _P of the steered wheels 24FL and 24FR becomes the target turning angle θ _P1. Then, the variable gear ratio unit 14 operates.

On the other hand, an operation signal is output from the ECU 30 to each of the shock absorbers 42 (step S4).
4). The damping force of each shock absorber is adjusted according to the operation signal so as to decrease.

As described above, according to the vehicle steering control device 2c according to the present embodiment, when the characteristics of the suspension are adjusted by the driver and the dynamic characteristics of the vehicle are changed, the changed dynamic characteristics are changed. The transmission ratio is set in accordance with. Therefore, an optimum vehicle response characteristic according to the vehicle motion characteristic can be obtained. Therefore, the driver can operate the vehicle without feeling uncomfortable.

Further, when the characteristics of the suspension are adjusted softly, the transmission ratio increases, and abrupt movement of the vehicle body is suppressed, so that the riding comfort of the vehicle can be improved.

In the vehicle steering control device 2c according to the present embodiment, when the suspension characteristics are hardly adjusted by operating the suspension adjustment switch 46, a map having a small transmission ratio in each vehicle speed region is used. Set transmission ratio G to suspension adjustment switch 4
6 may be set smaller than before the operation. In this case, since the suspension characteristics are hardened and the transmission ratio is reduced, good responsiveness of the vehicle can be obtained.

When the suspension adjustment can be set in three or more stages by operating the suspension adjustment switch 46, the coefficient K1 may be set and the transmission ratio G may be changed accordingly.

(Fifth Embodiment) Next, a vehicle steering control device according to a fifth embodiment will be described.

The vehicle steering control devices according to the first to fourth embodiments change the transmission ratio characteristics according to the vehicle height adjustment or suspension adjustment when the vehicle height adjustment or suspension adjustment is performed. The transmission ratio is not limited to such a case, and the transmission ratio may be changed in response to the change of the vehicle motion characteristics by another method.

That is, the vehicle steering control device according to the present embodiment changes the transmission ratio in response to the selection of the snow mode by the driver. Here, the snow mode is an operation mode in which a second gear is set at the time of starting, and prevents a wheel spin at the time of starting to enable a smooth start. As shown in FIG. 8, the vehicle speed-transmission ratio characteristic in the snow mode is set to be larger than the vehicle speed-transmission ratio characteristic in the normal running mode (normal mode) so that the transmission ratio becomes larger, and when the snow mode is selected. To increase the transmission ratio. This process of changing the transmission ratio may be performed based on the flowchart shown in FIG. 2 or FIG.

Even in such a vehicle steering control device, when the snow mode is selected by the driver and the motion characteristics of the vehicle are changed, the above-described first to fourth embodiments will be described. In the same manner as the vehicle steering control device,
The transmission ratio is set according to the changed motion characteristic. Therefore, an optimum vehicle response characteristic according to the vehicle motion characteristic can be obtained. Therefore, the driver can operate the vehicle without feeling uncomfortable. In this case, by increasing the transmission ratio on a snowy road, rapid movement of the vehicle body is suppressed, and the traveling of the vehicle becomes stable.

Further, the vehicle steering control device according to the present embodiment may change the transmission ratio in response to selection of the sport shift mode by the driver. Here, the sport shift mode is a traveling mode in which the shift position can be changed by a driver's shift operation in an automatic transmission vehicle. FIG.
As shown in the figure, the vehicle speed-transmission ratio characteristic in the sports shift mode is set so that the transmission ratio is smaller than the vehicle speed-transmission ratio characteristic in the normal traveling mode (normal), and the sports shift mode is selected. The transmission ratio is reduced. The change of the transmission ratio may be performed based on the flowchart shown in FIG. 2 or FIG.

Even in such a vehicle steering control apparatus, when the sports shift mode is selected by the driver and the motion characteristics of the vehicle are changed, the above-described first to fourth embodiments will be described. Similarly, the transmission ratio is set in accordance with the changed motion characteristic. Therefore, an optimum vehicle response characteristic according to the vehicle motion characteristic can be obtained. Therefore, the driver can operate the vehicle without feeling uncomfortable. In this case, the response of the vehicle body can be improved by reducing the transmission ratio. If a plurality of shift modes can be set, the transmission ratio may be changed using a vehicle speed-transmission ratio characteristic map adapted to each shift mode.

[0075]

As described above, according to the present invention, the following effects can be obtained.

That is, when the motion characteristics of the vehicle are changed, the transmission ratio is set in accordance with the changed motion characteristics, so that the optimum vehicle response characteristics according to the motion characteristics of the vehicle can be obtained. Therefore, the driver can operate the vehicle without feeling uncomfortable.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a vehicle steering control device according to a first embodiment.

FIG. 2 is a flowchart showing an operation of the vehicle steering control device according to the first embodiment.

FIG. 3 is a diagram illustrating a relationship between a vehicle speed and a transmission ratio in the vehicle steering control device according to the first embodiment.

FIG. 4 is a diagram illustrating a relationship between a vehicle speed and a transmission ratio in a vehicle steering control device according to a second embodiment.

FIG. 5 is a diagram illustrating a relationship between a vehicle speed and a transmission ratio in a vehicle steering control device according to a second embodiment.

FIG. 6 is a flowchart showing an operation of the vehicle steering control device according to the second embodiment.

FIG. 7 is an explanatory diagram of a vehicle steering control device according to a third embodiment.

FIG. 8 is a diagram illustrating a relationship between a vehicle speed and a transmission ratio in a vehicle steering control device according to a fifth embodiment.

FIG. 9 is a diagram showing a relationship between a vehicle speed and a transmission ratio in a vehicle steering control device according to a fifth embodiment.

[Explanation of symbols]

2 ... Vehicle steering control device, 10 ... Steering handle, 14 ... Variable gear ratio unit, 24FR, 24FL ...
Steered wheels, 30 ... ECU, 32 ... Air spring, 38 ...
Vehicle speed sensor.

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 19, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

The variable gear ratio unit 14 varies the transmission ratio between the amount of steering of the steering wheel 10 and the amount of steering of the steered wheels 24FL and 24FR, and includes a motor (not shown), a planetary gear mechanism or a harmonic. And a speed reducer (not shown) using a drive (registered trademark: wave gear) mechanism or the like. The variable gear ratio unit 14
It is connected to the ECU 30 via the motor drive 36, and operates upon receiving a control signal from the ECU 30.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification code FI B62D 131: 00 137: 00 (72) Inventor Tadashi Kawamuro 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation

Claims (3)

[Claims] A transmission ratio variable means provided in a steering transmission system for connecting a steering wheel and a steered wheel, and varying a transmission ratio between a steering amount of the steering wheel and a steered amount of the steered wheel; A steering control device for a vehicle, comprising: a motion characteristic changing unit that changes a motion characteristic of a vehicle; and a changing unit that causes the transmission ratio variable unit to change the transmission ratio in accordance with a change in the motion characteristic of the vehicle. 2. The vehicle steering control device according to claim 1, wherein the motion characteristic varying unit is a vehicle height varying unit that changes a height of the vehicle. 3. The vehicle steering control device according to claim 1, wherein the motion characteristic varying means is a damping force characteristic varying means for changing a damping force characteristic of a suspension of the vehicle.