JPH11245835A - Steering device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a desired steering feeling of individual driver according to travel conditions and steering conditions by providing an adjusting means that manually changes an auxiliary reaction torque value added to an auxiliary steering torque value step-like or continuously over specific steps. SOLUTION: A multi-stage switch 18 as an adjusting means, which manually changes a ratio of an auxiliary steering torque to an auxiliary reaction torque and/or a sum of the auxiliary steering torque and the auxiliary reaction torque step-like over two steps by multiplying a desired coefficient to them, is connected with an auxiliary steering torque determining means 17a and an auxiliary reaction torque determining means 17b. This multi-stage switch 18 selects three positions, for example a city area, a high way, and a winding road, and sets coefficients multiplied to the auxiliary steering torque and the auxiliary reaction torque so as to provide turbulence restraining effect and steering feeling according to each travel road. Thus, drivers can get a desired steering feeling only by selecting a position according to their travel road.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering apparatus for a vehicle, and more particularly to a steering apparatus configured to be able to generate an appropriate steering reaction torque and a steering torque for suppressing the behavior of the vehicle when a disturbance occurs by an electric motor. It is.

[0002]

2. Description of the Related Art As a so-called power steering device for reducing a driver's steering force, for example, Japanese Patent Publication No. 50-33
A type as described in Japanese Patent No. 584 is known. This is designed to assist the steering force of the steering wheel with the output torque of the electric motor. The amplification of the detection signal of the steering torque applied by the driver to the steering wheel is detected by detecting the vehicle speed and road conditions. The output torque of the auxiliary motor is increased or decreased by changing the output torque according to a signal, so that an optimum steering torque is always obtained.

[0003] By the way, if the vehicle receives a strong crosswind or travels on a rutted road while traveling, the vehicle may be deflected in a direction deviating from the target traveling line. In addition, the road surface reaction force decreases when traveling on a road surface having a low friction coefficient (μ) between the tire and the road surface such as a snowy road (hereinafter referred to as a low μ road) or when traveling at low speed.

In the case of the above-described conventional power steering device, the electric motor generates the auxiliary steering torque only after the driver turns the electric power steering device. No auxiliary steering torque is generated. Therefore, in order to suppress the deflection of the vehicle, the driver himself must operate the steering wheel. On the other hand, the power steering device generally requires a larger steering force as the lateral acceleration and the yaw rate of the vehicle increase. Therefore, in the case of the deflection of the vehicle due to the disturbance, there is a problem that the larger the deflection, the larger the steering torque required for the correction.

Therefore, for example, Japanese Patent Laid-Open No. 5-105100 discloses that a vehicle behavior such as a yaw rate and a lateral acceleration is detected, and an auxiliary reaction torque value is determined based on the detected value.
A motor that controls the drive torque of the electric motor based on the auxiliary reaction torque value and an auxiliary steering torque value determined based on a detection value such as a steering torque has been proposed.

According to this structure, the deflection suppressing performance when disturbance such as crosswind or running on a rutted road acts on the vehicle can be enhanced, and the running stability of the vehicle can be improved. The steering operation load is reduced even at low speeds.

[0007]

Incidentally, the above-mentioned auxiliary steering reaction torque includes a damping torque having a steering angular velocity as a parameter and a yaw rate torque having a yaw rate as a parameter. And the frequency response characteristics differ between high-speed running. In particular, a peak due to yaw resonance appears in the gain in a relatively high frequency region during high-speed running. Then, in the conventional steering apparatus having the above-described structure, since the input yaw rate and the output yaw rate torque have a one-to-one correspondence, the yaw rate torque is large near the peak. It is conceivable that the steering input in the frequency domain is affected, and that the steering wheel becomes unnaturally uncomfortable. In particular, when the ratio of the auxiliary steering reaction torque to the total steering torque is increased in order to increase the effect of suppressing the vehicle behavior during a disturbance, the above problem becomes significant. On the other hand, when running, letting go, or in a lightly-steered state, it is preferable to increase the ratio of the auxiliary steering reaction torque to the total steering torque to increase the effect of suppressing the vehicle behavior due to the disturbance.

The present invention has been devised in order to improve such disadvantages of the prior art. A first object of the present invention is to enhance the deflection suppressing performance when a disturbance is applied and to increase the steering force during a normal turning. It is an object of the present invention to provide a vehicle steering system that can appropriately set the steering angle and can obtain a desired steering feeling of each driver according to a traveling state and a steering state. Also,
A second object is a vehicle capable of appropriately setting the deflection suppression performance at the time of disturbance and the steering force at the time of normal turning in accordance with the running state and the steering state, and improving the steering feeling comprehensively. To provide a steering device for a vehicle.

[0009]

SUMMARY OF THE INVENTION The first object described above is intended to provide:
According to the present invention, manual steering means for manually turning a steered wheel of a vehicle, steering torque detection means for detecting a steering torque applied to the manual steering means, and detection of the steering torque detection means Auxiliary steering torque determining means for determining an auxiliary steering torque based on the value, vehicle behavior detecting means for detecting the behavior of the vehicle, and determining an auxiliary reaction torque based on a detection value detected by the vehicle behavior detecting means. An auxiliary reaction torque determining means, an electric motor for applying an auxiliary torque to the steered wheels, and an auxiliary steering torque value determined by the auxiliary steering torque determining means. In a vehicle steering apparatus for controlling the electric motor with an auxiliary torque value obtained by adding a reaction torque value, the auxiliary reaction torque value to be added to the auxiliary steering torque value is manually calculated. In it is achieved by providing a vehicle steering apparatus characterized by comprising adjusting means for stepwise or continuously changing in two or more stages. A second object of the present invention is to provide a manual steering means for manually turning a steered wheel of a vehicle, a steering torque detecting means for detecting a steering torque applied to the manual steering means, Auxiliary steering torque determining means for determining an auxiliary steering torque based on the detection value of the torque detecting means; vehicle behavior detecting means for detecting the behavior of the vehicle; and assisting based on the detection value detected by the vehicle behavior detecting means. Auxiliary reaction torque determining means for determining a reaction torque; an electric motor for applying an auxiliary torque to the steered wheels; and an auxiliary steering torque determining means for determining an auxiliary steering torque value determined by the auxiliary steering torque determining means. Means for determining the running state of the vehicle in a vehicle steering system that controls the electric motor with an auxiliary torque value obtained by adding the auxiliary reaction torque value determined by Means for determining the steering state of the driver, and the auxiliary reaction torque value to be added to the auxiliary steering torque value in two or more steps according to the determined driving state of the vehicle and / or the driver's steering state. Alternatively, the present invention is attained by providing a vehicle steering system having a continuously changing adjusting means.

With this configuration, the driver can obtain a desired steering feeling according to the situation, and can increase the auxiliary reaction torque value to be added to the auxiliary steering torque value in two or more steps according to the running state of the vehicle. If it changes stepwise or continuously, it becomes possible to appropriately set the deflection suppression performance at the time of disturbance and the steering force at the time of normal turning according to the running state without bothering the driver.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a schematic configuration of a vehicle steering system according to a first embodiment to which the present invention is applied. This device includes a pinion 4 connected to a steering shaft 2 integrally connected to a steering wheel 1 via a connection shaft 3 having a universal joint, and can reciprocate in the vehicle width direction by meshing with the pinion 4 and a tie rod 5. And a rack and pinion mechanism having a rack shaft 8 having both ends connected to knuckle arms of left and right front wheels 6 serving as steered wheels via the steering wheel. In addition, an electric motor 9 constituting an electric power steering apparatus is provided so as to add an auxiliary torque obtained by adding an auxiliary steering torque and an auxiliary reaction torque described later to a manual steering force via a rack and pinion mechanism. Are coaxially arranged at the intermediate portion of the rack shaft 8.

In the vicinity of the pinion 4 of the rack and pinion mechanism, a steering angular velocity sensor 11 for detecting a steering angular velocity from the rotation angle of the steering wheel 1 and a steering for detecting a manual steering torque acting on the pinion 4 are provided. A torque sensor 12 is provided as torque detecting means. Also, the yaw rate of the vehicle (yawing angular velocity)
Sensor 15 for outputting a signal corresponding to
And a vehicle speed sensor 16 for outputting a signal corresponding to the running speed of the vehicle. Each of these sensors is connected to a steering control unit 17 for controlling the output of the electric motor 9 based on the detected value. ing.

As shown in FIG. 2, an auxiliary steering torque determining means 17a for calculating an auxiliary steering torque as an electric power steering apparatus and an auxiliary reaction torque are calculated in the steering control unit 17 described above. And an auxiliary reaction torque determining means 17b. The auxiliary steering torque determining means 17a includes a steering angular velocity sensor 11
The detection signals of the torque sensor 12 and the vehicle speed sensor 16 are input, and the auxiliary steering torque for performing the normal assist control is determined according to the detection signals.

The auxiliary reaction torque determining means 17b receives the detection signals of the steering angular velocity sensor 11, the yaw rate sensor 15, and the vehicle speed sensor 16 which constitute the vehicle behavior detecting means. The auxiliary reaction torque is determined by an algorithm described later.

The auxiliary steering torque determining means 17a and the auxiliary reaction torque determining means 17b are multiplied by a desired coefficient to the auxiliary steering torque and the auxiliary reaction torque, and the ratio between the two is calculated.
Alternatively, a multi-stage switch 18 is connected as adjusting means for manually changing the sum of the auxiliary steering torque and the auxiliary reaction torque, that is, the actual auxiliary torque in two or more steps.

In the steering control unit 17, target current determining means 17c for setting a target current for the electric motor 9 in accordance with each torque value output from the auxiliary steering torque determining means 17a and the auxiliary reaction force determining means 17b, Output current control means 17d for controlling the current flowing to the electric motor 9 according to the target current is provided. Then, a current control signal from the output current control means 17d is input to a drive circuit 19 provided between the steering control unit 17 and the electric motor 9,
The drive circuit 19 drives the motor 9 by, for example, PWM control, and performs feedback control of the output current between the drive circuit 19 and the output current control means 17d.

In the auxiliary reaction torque determining means 17b in the steering control unit 17, the processing shown in the flowchart of FIG. 3 is repeatedly executed at a predetermined cycle. First, the signal output of each sensor is read in step 1, the target steering reaction torque value TA is determined in step 2, and then the limit is applied to the target steering reaction torque value TA in step 3. In step 4, the coefficient a according to the setting of the multi-step switch 18 is multiplied by the target steering reaction torque value TA, and in step 5, this control signal is added to the output signal from the auxiliary steering torque determining means 17a.

This processing will be described in more detail with reference to FIGS. First, in step 1 above,
As shown in the flowchart of FIG. 4, processing for reading the vehicle speed V (step 11), the steering wheel angular velocity ω (step 12), and the yaw rate γ (step 13) is performed.

Next, in step 2 described above, as shown in the flowchart of FIG. 5, first, the steering angular velocity ω as shown in FIG. 7A is used as an address, and different characteristics are set for each vehicle speed V. An auxiliary reaction torque value T1 (damping torque component) is obtained from the data table (step 21). Further, in step 22, the actual reaction yaw rate γ is used as an address, and an auxiliary reaction force torque value T2 as a yaw rate torque component is obtained from a data table (FIG. 7B) set to have different characteristics for each vehicle speed V.

Each of the auxiliary steering reaction torque values T1 and T2
To obtain the auxiliary reaction torque value TA (step 2
3).

Next, the target steering reaction torque value TA is increased to a maximum value (Tma) in order to eliminate unnecessary auxiliary reaction torque.
x) is determined, and if the target steering reaction torque value TA exceeds the maximum value, the target steering reaction torque value TA is set to the above Tmax, and the target steering reaction torque value TA is set to Tmax. If the maximum value (Tmax) is not exceeded,
Similarly, the target steering reaction torque value TA is a negative maximum value (−Tm
ax) is determined, and if the target steering reaction torque value TA exceeds the negative maximum value, a limiter process is performed to set the target steering reaction torque value TA to the above-mentioned -Tmax value (step 24). I do.

Then, the auxiliary reaction force torque value TA obtained in this way is multiplied by a coefficient a according to the setting of the multi-step switch 18 to determine an auxiliary reaction force torque determination value TA (step 25).

FIG. 6 is a control block diagram of the above step 2, and steps 21 to 25 correspond to the respective blocks in FIG.

On the other hand, the output signal from the auxiliary steering torque determining means 17a, that is, the auxiliary steering torque value is also multiplied by a coefficient b according to the setting of the multi-stage switch 18 to obtain an auxiliary steering torque determined value (not shown).

Then, the auxiliary steering torque determination value (auxiliary steering torque value) and the auxiliary reaction force torque determination value (auxiliary reaction force torque value) TA are added to obtain a target current value by the target current determination means 17c as an auxiliary torque value. And supplies it to the electric motor 9 to generate auxiliary torque.

By performing the above processing, as shown in FIG. 8, when the vehicle 20 comes off the traveling line 21 due to the crosswind during forward movement, the yaw rate γ of the vehicle 20 at this time is detected. In the direction to cancel the yaw rate γ, that is, the deflection of the vehicle 20 at that time is
Motor 9 is driven in the direction to return to
The front wheel 6 is automatically steered so that the vehicle 20 always travels straight, so that the irregular behavior can be stabilized, and the vehicle 20 travels straight even when traveling on a rutted road surface or a puddle road surface. In this way, the effect of automatically correcting the trajectory is obtained.

Further, for example, the multi-stage switch 18 is configured as follows:
Urban area, 2-highway, 3-winding road
It is assumed that the position can be selected, and by setting as shown in Table 1, it is possible to obtain characteristics that are light and resistant to disturbance in the city area, and that on the winding road, a firm response to the steering wheel and high disturbance suppression effect Obtained
On a highway, high straight running stability and disturbance suppression effects can be obtained.

[0029]

[Table 1] Table 1

The driver can obtain a desired steering feeling if the driver selects any position according to the traveling path.

In this embodiment, the multi-stage switch 18 acts on both the auxiliary steering torque value and the auxiliary reaction torque value. However, the multi-stage switch 18 may operate only on the auxiliary reaction torque value. Also, a stepless switch such as a variable resistor is provided in place of the multi-step switch 18, and the coefficients a and b corresponding to the set positions are obtained in an analog manner, and these are multiplied by the auxiliary steering torque value and the auxiliary reaction torque value. You may do it.

FIG. 9 is a view similar to FIG. 2 showing a second embodiment according to the present invention, and the same parts as those in FIG. 2 are denoted by the same reference numerals, and detailed description thereof will be omitted. In this embodiment,
Instead of the multi-stage switch 18, the traveling state determining means 28 includes an auxiliary steering torque determining means 17 a and an auxiliary reaction
b. The traveling state determination means 28 determines whether the traveling state of the vehicle is 1-city area, 2-highway, 3-winding road based on data input from the steering angular velocity sensor 11, the yaw rate sensor 15, and the vehicle speed sensor 16. Is determined as shown in Table 2 below, for example.

[0033]

[Table 2] Table 2

The coefficients a and b according to the result of the judgment
Is multiplied by the auxiliary reaction torque value and the auxiliary steering torque value.

FIG. 10 is a view similar to FIG. 9 showing a third embodiment according to the present invention. Parts similar to those in FIG. 9 are denoted by the same reference numerals, and detailed description thereof will be omitted. In the present embodiment, in addition to the running state determining means 28, a steering state determining means 29 for determining the steering state of the driver is also connected to the auxiliary steering torque determining means 17a and the auxiliary reaction torque determining means 17b. The determining means 28 multiplies the auxiliary reaction force torque value and the auxiliary steering torque value by the coefficients a1 and b1 corresponding to the same determination result as described above, and
Based on each signal output from the control unit 6, it is estimated (detected) whether the driver is holding or steering the steering wheel while holding the steering wheel or almost in a released state by an algorithm described later, and a coefficient corresponding to the result is obtained. a2 and b2 are also multiplied by the auxiliary reaction torque value and the auxiliary steering torque value.

Next, the procedure for determining the steering state of the driver by the steering state determination means 29 will be described in detail. Here, the steering state of the driver is detected based on the following equation. First, the equation of motion around the steering wheel is

[0037]

(Equation 1)

When the entire expression is integrated over time,

[0039]

(Equation 2)

By transforming this,

[0041]

(Equation 3)

Here, TS (kg · cm) is a torque sensor value, TH (kg · cm) is steering or steering torque, ω
(Deg · sec) is the steering angular velocity, and JH (kg · m) is the inertia of the steering wheel.

TH is obtained from the fact that the measured values of TS and ω are obtained. That is, if the calculation result on the left side of the equation (3) is 0, the driver has almost released the steering wheel, and if not 0, it is determined that the driver is holding or steering the steering wheel. I do.

Actually, the calculation of equation (3) is performed from time t = 0 to time t = X.

[0045]

(Equation 4)

Where ωX is the steering angular velocity at time X.

At this time, since the integration from the time t = 0 is affected by the offset, the first term of the equation (4) is divided into two at the time t = X−N.

[0048]

(Equation 5)

Further, the first term of the equation (5) is changed to a time t = X
-N at the steering angular velocity ωX-N,

[0050]

(Equation 6)

Thus, from time t = X−N to time t
TH is obtained by performing integration up to X.

From the TH obtained in step 23, it is determined how much the driver is holding or steering the steering wheel or almost releasing the steering wheel. Then, depending on the degree, that is, if the degree of steering or steering is large, the auxiliary steering reaction torque is reduced to reduce the uncomfortable steering feeling at high speeds, etc. The coefficients a2 and b2 are set so that the auxiliary steering reaction torque is increased according to the degree to enhance the disturbance suppression effect.
And multiply the auxiliary reaction torque value and the auxiliary steering torque value.

In the above configuration, the yaw rate sensor is used as the vehicle behavior detecting means. However, a similar operation and effect can be obtained by using a lateral acceleration sensor instead or in addition to this.

[0054]

As described above, according to the vehicle steering system of the present invention, the auxiliary reaction torque value to be added to the auxiliary steering torque value can be manually changed stepwise or continuously in two or more steps. The driver can obtain a desired steering feeling according to the situation. A means for determining a driver's steering state and / or a means for determining a vehicle's running state; and an auxiliary steering torque value added to an auxiliary steering torque value according to the determined driver's steering state and / or vehicle running state. By changing the force torque value stepwise or continuously in two or more steps, the deflection suppression performance at the time of disturbance and the steering force at the time of normal turning are bothered by the driver according to the running state and the steering state. Can be set appropriately without the need.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram schematically showing a vehicle steering system according to a first embodiment to which the present invention is applied.

FIG. 2 is a circuit block diagram of a control system of the steering device.

FIG. 3 is a flowchart showing a control process of the steering device.

FIG. 4 is a flowchart showing control processing of the steering device.

FIG. 5 is a flowchart showing control processing of the steering device.

FIG. 6 is a circuit block diagram of a control system of the steering device and a data table used for the control processing.

FIGS. 7A and 7B are enlarged views of a data table used for the control processing; FIG.

FIG. 8 is a schematic diagram showing the movement of the vehicle when a crosswind is received during straight running.

FIG. 9 is a circuit block diagram of a control system of a vehicle steering system according to a second embodiment to which the present invention is applied.

FIG. 10 is a circuit block diagram of a control system of a vehicle steering system according to a third embodiment to which the present invention is applied.

[Explanation of symbols]

 Reference Signs List 1 steering wheel 2 steering shaft 3 connecting shaft 4 pinion 5 tie rod 6 front wheel 8 rack shaft 9 electric motor 11 steering angular velocity sensor 12 torque sensor 15 yaw rate sensor 16 vehicle speed sensor 17 steering control unit 17a auxiliary steering torque determining means 17b auxiliary reaction force determining means 17c Target current determining means 17d Output current controlling means 18 Multi-stage switch 19 Drive circuit 20 Vehicle 21 Straight running line 28 Running state determining means 29 Steering state determining means

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B62D 137: 00 (72) Inventor Kazushige Sumatama 1-4-1 Chuo, Wako-shi, Saitama Pref. 72) Inventor Hiroyuki Kawagoe 1-4-1, Chuo, Wako-shi, Saitama Pref.Honda R & D Co., Ltd. (72) Inventor Tatsuya Nishikawa 1-4-1, Chuo, Wako-shi, Saitama Pref.Honda R & D Co., Ltd.

Claims (3)

[Claims] 1. A manual steering device for manually turning a steered wheel of a vehicle, a steering torque detecting device for detecting a steering torque applied to the manual steering device, and a detection value of the steering torque detecting device. Auxiliary steering torque determining means for determining an auxiliary steering torque based on a vehicle behavior detecting means for detecting a behavior of the vehicle, and determining an auxiliary reaction torque value based on a detection value detected by the vehicle behavior detecting means An auxiliary reaction torque determining means, an electric motor for applying an auxiliary torque to the steered wheels, and an auxiliary steering torque value determined by the auxiliary steering torque determining means. In a vehicle steering system that controls the electric motor with an auxiliary torque value obtained by adding a reaction torque value, the auxiliary reaction force torque value to be added to the auxiliary steering torque value is manually calculated. In vehicle steering apparatus characterized by comprising adjusting means for stepwise or continuously changing in two or more stages. 2. A manual steering device for manually turning a steered wheel of a vehicle, a steering torque detecting device for detecting a steering torque applied to the manual steering device, and a detection value of the steering torque detecting device. Auxiliary steering torque determining means for determining an auxiliary steering torque based on a vehicle behavior detecting means for detecting a behavior of the vehicle, and determining an auxiliary reaction torque based on a detection value detected by the vehicle behavior detecting means. An auxiliary reaction torque determining means, an electric motor for applying an auxiliary torque to the steered wheels, and an auxiliary reaction torque determined by the auxiliary reaction torque determining means to an auxiliary steering torque value determined by the auxiliary steering torque determining means. In a vehicle steering system that controls the electric motor with an auxiliary torque value obtained by adding a force torque value, a means for determining a running state of the vehicle, and a running state of the determined vehicle Vehicle steering apparatus characterized by comprising an adjustment means for stepwise or continuously changing the auxiliary reaction force torque value applied to the auxiliary steering torque value in two or more stages depending on the. 3. The vehicle according to claim 1, further comprising: means for determining a steering state of the driver, wherein the adjusting means adds the auxiliary steering torque value to the auxiliary steering torque value according to the determined steering state of the driver and / or the traveling state of the vehicle. The vehicle steering system according to claim 2, wherein the auxiliary reaction torque value is changed stepwise or continuously in two or more steps.