JP2003175845A - Power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power steering device capable of affording suitable steering characteristics corresponding to various operating condition. <P>SOLUTION: Wheel speed of each wheel is taken into ECU1 at the step 110. A steering angle is taken in at the step 120 and an angular velocity is calculated with using the steering angle and taken in. An engine rotation speed is taken in and the engine rotation acceleration is calculated with using the engine rotation speed and taken in at the step 130. Lateral G is taken in at the step 140 and a yaw rate is taken in at the step 150. Signal from a stop lamp SW21 is taken in at the step 160 and signal from a mode-switching SW23 is taken in at the step 170. Suspension rigidity control is performed based on the signal taken in by ECU1 at the step 180 and the control for power steering assist amount is performed at the step 190. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power steering system which can obtain suitable steering characteristics according to the driving condition of a vehicle.

[0002]

2. Description of the Related Art Conventionally, it is known that steering characteristics such as steering stability and steering feeling of a vehicle can be changed by changing steering characteristics of a power steering device. For example, when the assisting force (steering assisting force) in the power steering is reduced, the response during steering becomes dull and the steering feeling becomes dull, and when the assisting force is increased, the response becomes sharp. The steering feel becomes sharp.

As an example of changing the steering characteristic, for example, the steering operation force is changed according to the vehicle speed, and the steering is heavy at high speed to increase the straight running stability.
It is known that the steering is lightened at low speed to improve the turning performance. Further, in recent years, a change in steering characteristics caused by a change in suspension characteristics can be represented by a sharpness of responsiveness and a magnitude of steering force, and a change in steering characteristics caused by a change in steering characteristics is the same. In addition, paying attention to the point that it can be expressed by the sharpness of responsiveness and the magnitude of steering force, and by controlling by combining the change of suspension characteristic and the change of steering characteristic, the steering characteristic is further promoted and further increased. Alternatively, or conversely, there has been proposed a technique for canceling the change to reduce the change (see Japanese Patent Laid-Open No. 59-106371).

However, in the above-mentioned technique, steering characteristics such as steering stability and steering feeling of the vehicle, which can appropriately cope with various driving states such as a case where a cross wind is received or when turning, are not always sufficient. Therefore, further improvement has been desired. The present invention has been made to solve the above problems, and an object of the present invention is to provide a power steering device that can obtain suitable steering characteristics in response to various driving conditions.

[0005]

To achieve this object, the invention of claim 1 is a power steering apparatus for adjusting an assist amount which is an auxiliary steering force applied to a steering wheel, as shown in FIG. Wheel speed detection means for detecting a speed, sprung resonance frequency extraction means for extracting a sprung resonance frequency component based on a variation state of the wheel speed detected by the wheel speed detection means, and the sprung resonance frequency extraction means SUMMARY OF THE INVENTION A gist of a power steering apparatus is characterized in that it includes: an assist amount setting means for setting an assist amount of power steering based on the sprung resonance frequency component extracted by.

A second aspect of the present invention provides the power steering apparatus according to the sixth aspect, wherein the assist amount of the power steering is reduced as the sprung resonance frequency component is increased.

[0007]

According to the invention of claim 1, the sprung resonance frequency component is extracted based on the variation state of the wheel speed,
Since the assist amount of the power steering is set based on the sprung resonance frequency component, the power steering device is preferably controlled according to the driving state of the vehicle by using the signal of the wheel speed used in the ABS control, for example. be able to.

According to the second aspect of the present invention, the larger the sprung resonance frequency component is, the more the assist amount of the power steering is reduced. Therefore, the steering stability and the steering feeling in an unstable state where the vehicle is tilted are improved. .

[0009]

Preferred embodiments of the present invention will be described below in order to further clarify the structure and operation of the present invention described above. FIG. 2 shows a vehicle equipped with the power steering device of the present embodiment, in which the operating state of the vehicle is detected by various sensors, and various actuators are drive-controlled based on the detected operating state. Control such as power steering assist amount control and suspension rigidity control described later is performed.

As shown in FIGS. 2 and 3, in this embodiment, as sensors, a wheel speed sensor 7 for detecting the rotational speed of each wheel, an engine rotational speed sensor 9 for detecting the engine rotational speed, A steering angle sensor 13 that detects the rotation angle (steering angle) of the steering wheel 11, a vertical G sensor 15 that detects vertical acceleration (G), a lateral G sensor 17 that detects lateral G, and a yaw rate sensor that detects yaw rate. 19, a stop lamp switch (hereinafter, switch is referred to as SW) 21 for detecting that the brake pedal is depressed, and a mode switching SW 23 for switching the setting state of the damping force between the sports mode and the normal mode.

Further, as actuators, a hydraulic motor 25 and a hydraulic pump 27 that supply hydraulic pressure to drive the power steering 3 (assist), a damping force switching actuator 29 that switches the damping force of the shock absorber 5, and a sensor disconnection. And a warning lamp 31 for reporting an abnormality such as.

Further, by inputting the signals from the respective sensors,
An electronic control device (EC) that performs various calculations based on the signal and outputs a control signal to each of the actuators
U) 1. Next, a basic control procedure of the power steering apparatus of the present embodiment having the above configuration will be described based on the flowchart of FIG.

First, in step 100 of FIG. 4, initialization is performed, and in step 110, the wheel speed sensor 7 is initialized.
The wheel speed of each wheel is fetched into the ECU 1 based on the signal from the. The wheel speed sensor 7 may be a sensor used for ABS control.

In the following step 120, the steering angle is fetched based on the signal from the steering angle sensor 13, and the angular velocity of the steering angle is calculated and fetched using the steering angle. In the following step 130, the engine rotation speed is fetched based on the signal from the engine rotation speed sensor 9, and the engine rotation acceleration is calculated and fetched using the engine rotation speed.

In the following step 140, the lateral G sensor 17
Take in the lateral G based on the signal from the following step 1
At 50, the yaw rate is fetched based on the signal from the yaw rate sensor 19. In the following step 160, the signal from the stop lamp SW21 is captured, and in the following step 170, the signal from the mode switching SW23 is captured.

In the following step 180, the suspension rigidity control, which will be described in detail later, is performed based on the signal taken in by the ECU 1 as described above, and in the following step 190, the power steering assist amount control, which is also described later in detail, is performed. And go back to step 110.

Next, various control processes performed in this embodiment will be sequentially described in detail.

(1) Vehicle Speed Sensitive Control of Power Steering As shown in FIG. 5, in this processing, in step 200, the wheel speed of each wheel is fetched based on the signal from the wheel speed sensor 7.

In step 210, as shown in Table 1 below, the vehicle body speed is calculated according to the wheel speed to be used.

[0020]

[Table 1] In the following step 220, the assist amount which is the steering assist force of the power steering is calculated. When calculating the assist amount, the calculation method is slightly different depending on which of the vehicle speed calculation methods (1) to (10) in Table 1 above is used.

Specifically, in the case of (1) (the wheel speed of one wheel is used as it is), for example, a map showing the relationship between the vehicle body speed and the assist amount as shown in FIG. To calculate. Thereby, the assist amount can be obtained by the simplest calculation. The map in Figure 6 is
The assist amount is set to decrease as the vehicle body speed increases, but this is because when the vehicle body moves at a high speed, the force for turning the steering wheel is not required so much.

In the case of (2) (using a filter), the influence of the unevenness of the road surface can be removed by the filter, so that the wheel speed can be detected more accurately, and thus the assist amount can be obtained accurately. In the case of (3) (average value of left and right wheels), when the vehicle turns, the vehicle body speed can be calculated more accurately, and the assist amount can be accurately obtained.

In the case of (4) (driving wheel; maximum value of left and right wheels), the acceleration slip can be detected by selecting the maximum value. Therefore, in that case,
As shown in FIG. 6, the larger the vehicle speed is, the smaller the assist amount is set, and the steering force becomes heavy at the time of the acceleration slip, so that the safety is improved.

In the case of (5) (minimum value of left and right wheels),
By selecting the minimum value, the braking lock state (for example, the one-wheel lock state) can be detected. Therefore, in that case, as shown in FIG. 7, a smaller assist amount is set as the vehicle speed becomes smaller, and the steering force becomes heavier when the brake is locked, so that the safety is improved.

In the case of (6) (average value of four wheels), for example, when the vehicle turns, the vehicle speed can be calculated more accurately, and the assist amount can be accurately obtained. In the case of (maximum value of four wheels) of (7), the above (4)
Similarly, by selecting the maximum value, the acceleration slip can be detected. Therefore, in this case, as shown in FIG. 6, a smaller assist amount is set as the vehicle speed increases, and the steering force becomes heavier at the time of the acceleration slip, so that the safety is improved.

In the case of (8) (minimum value of four wheels), the braking lock state can be detected by selecting the minimum value as in (5) above. Therefore, in that case, as shown in FIG. 7, a smaller assist amount is set as the vehicle speed becomes smaller, and the steering force becomes heavier when the brake is locked, so that the safety is improved.

In the case of (9) (maximum value of front two-wheel average and rear two-wheel average), acceleration slip is detected by selecting the maximum value in the same manner as in (4) and (7) above. can do. Therefore, in this case, as shown in FIG. 6, a smaller assist amount is set as the vehicle speed increases, and the steering force becomes heavier at the time of the acceleration slip, so that the safety is improved.

In the case of (10) (minimum value of front two-wheel average and rear two-wheel average), the braking lock state is set by selecting the minimum value as in (5) and (8) above. Can be detected. Therefore, in that case, FIG.
As shown in, the smaller the vehicle speed, the smaller the assist amount is set, and the steering force becomes heavier when the brake is locked, so that the safety is improved.

Then, in the following step 230, the calculated assist amount is output, and the present processing is temporarily terminated. In this way, in this process, the vehicle speed is calculated using the wheel speed,
Since the assist amount is reduced as the speed increases, there is an effect that steering characteristics such as steering stability and steering feeling are improved.

Further, when not only one wheel but two or four wheel speeds are used, the vehicle speed detection accuracy is further improved,
The effect that a more suitable assist amount can be set is obtained. Furthermore, by using the average value, the maximum value, and the minimum value of each wheel speed, there is an advantage that the detection accuracy of the vehicle speed is improved corresponding to various driving states and a more suitable assist amount can be set.

(2) Control according to magnitude of sprung and / or unsprung resonance frequency component of wheel speed fluctuation As shown in FIG. 8, in this process, in step 300, the wheel speed sensor 7 outputs The wheel speed of each wheel is captured based on the signal.

In the following step 310, a sprung resonance frequency component (for example, 1 Hz to 2 Hz) and an unsprung resonance frequency component (for example, 10 Hz to 20 Hz) are extracted from the fluctuation of the wheel speed using a frequency filter. here,
When the resonance frequency component on the spring is 1 Hz to 2 Hz, the vehicle is fluffy (flapping), while when the resonance frequency component on the spring is 10 Hz to 20 Hz, the vehicle is fluttering (fluttering). In both cases, the condition of the vehicle is unstable, which is not preferable. Either one of the resonant frequency component on the spring and the resonant frequency component on the unsprung component may be extracted, or both may be extracted.

In the following step 320, the assist amount is calculated by using the map as shown in FIG. 9 according to the extracted sprung or lower resonance frequency component. In this case, separate maps are used for the sprung part and the unsprung part, but the map is such that the assist amount decreases as the signal strength of the resonance frequency component increases. This is because the steering force becomes heavier as the fluffy state or the flapping state becomes more remarkable, and the steering stability and the steering feeling are improved. When both the sprung and unsprung resonance frequency components are used, the steering stability and the steering feeling are further improved by setting the assist amount by using the smaller value.

In the following step 330, the calculated assist amount is output to perform assist control, and the present process is terminated. Here, an example of control of the assist amount is shown in FIG. As shown in FIG. 10, when the signal intensity of the sprung / unsprung resonance frequency component exceeds the control start threshold value (point A), the assist amount is reduced from the basic assist amount by the vehicle speed response at a constant rate. , The target value set corresponding to the maximum value (point B) of the sprung / unsprung resonance frequency components is made to follow. Similarly, when the maximum value (point C) larger than the point B is reached during the predetermined period T from the start of control, the assist amount is reduced at a constant rate from the time of the point C to increase the magnitude of the point C. The following target value set in accordance with After that, when the predetermined period T ends, a process of increasing the assist amount at a constant rate and returning to the basic assist amount is performed.

As described above, in this processing, the sprung resonance frequency component indicating the vertical motion of the vehicle body due to the unevenness of the road surface is extracted from the fluctuation of the wheel speed, and the sprung resonance frequency component is determined according to the magnitude of the sprung resonance frequency component. Control the amount of assist. Specifically, since the assist amount decreases as the sprung resonance frequency component increases, it is possible to prevent the vehicle from tilting and improve steering stability and steering feeling.

Similarly, the unsprung resonance frequency component is extracted from the fluctuation of the wheel speed, and the larger the unsprung resonance frequency component is, the smaller the assist amount is. Therefore, the fluttering of the vehicle is prevented and the steering stability is improved. And the steering feeling can be improved.

(3) Control when traveling on low μ road surface As shown in FIG. 11, in this processing, in step 400,
The wheel speed of each wheel is fetched based on the signal from the wheel speed sensor 7.

In the following step 405, the vehicle speed is calculated using this wheel speed in the same manner as in step 210. In the following step 410, the steering angle sensor 13
The steering angle is acquired based on the signal from.

In the following step 420, the lateral G sensor 17
Alternatively, the lateral G or the yaw rate is taken in based on the signal from the yaw rate sensor 19. Here, the lateral G and the yaw rate may be estimated from the difference between the left and right wheel speeds on the left and right sides, instead of the actual measurement, as in the following equations (1) and (2).

Lateral G = (V02-V12) /2.T.g (1) yaw rate = (V0-V1) / T (2) where V0: right wheel speed, V1: left wheel speed, T: trad, g: gravitational acceleration At step 430, the reference lateral G or the reference yaw rate is calculated. The standard lateral G and the standard yaw rate can be calculated as the lateral G and the yaw rate when an ideal trace is performed from the calculated vehicle speed and the steering angle.

In the following step 440, the road surface μ (friction coefficient) is estimated based on the difference between the reference lateral G or yaw rate and the actually measured or estimated lateral G or yaw rate. That is, the greater the difference between the standard (lateral G, yaw rate) value and the actually measured or estimated (lateral G, yaw rate) value, the more the vehicle body is slipping (oversteer or understeer state). It is determined that μ is small.

At the following step 450, the assist amount is calculated according to the estimated μ of the road surface using a map as shown in FIG. In this case, it is predicted that the smaller the road surface μ is, the more slippery and unstable the road surface becomes. Therefore, use a map in which the smaller the road surface μ, the smaller the assist amount. Improves steering stability and steering feel.

In the following step 460, the calculated assist amount is output to perform assist control, and the present process is temporarily terminated. As described above, in this processing, the standard lateral G or the standard yaw rate is obtained from the vehicle speed and the steering angle, the lateral G or the yaw rate is detected by the lateral G sensor 17 or the yaw rate sensor 19, and the difference between the standard value and the measured value is detected. Since the road surface condition is determined from the road surface μ and the road surface μ is estimated, and the assist amount is reduced when the road surface is low μ, the steering stability and steering feeling on the low μ road can be improved.

Similarly, the road surface μ is estimated from the reference lateral G or the reference yaw rate obtained from the vehicle speed and the steering angle and the lateral G or the yaw rate estimated from the difference between the left and right wheel speeds, and the road is a low μ road. In this case, since the assist amount is reduced, it is possible to improve steering stability and steering feeling on a low μ road.

(4) One-wheel lock, control during low μ road surface running, and water pool road surface running As shown in FIG. 13, in this processing, in step 500,
The wheel speed of each wheel is fetched based on the signal from the wheel speed sensor 7.

In the following step 510, the difference between the wheel speeds of the left and right wheels is calculated. In the following step 520, the assist amount is calculated using a map as shown in FIG. 14 according to the calculated wheel speed difference between the left and right wheels. In this case, the larger the wheel speed difference between the left and right wheels, the more slippery and unstable such as one-wheel lock, low μ road surface running, and water pool road surface running. A map is used such that the larger the amount, the smaller the assist amount, and the steering force is increased to improve the steering stability and steering feeling.

In the following step 530, the calculated assist amount is output to perform the assist control, and the present process is temporarily terminated. In this way, in this processing, when the wheel speed of the left and right wheels is high, it is determined that the vehicle is in a slippery and unstable state such as one-wheel lock, low μ road surface traveling, and water pool road surface traveling,
In such a case, since the assist amount is reduced, it is possible to improve steering stability and steering feeling in an unstable road surface condition.

(5) Control Corresponding to Steering State As shown in FIG. 15, in this processing, in step 600,
The wheel speed of each wheel is fetched based on the signal from the wheel speed sensor 7.

In the following step 605, the vehicle speed is calculated using the fetched wheel speed in the same manner as in step 210 described above. In the following step 610, the steering angle is fetched based on the signal from the steering angle sensor 13. Alternatively, the steering angular velocity is calculated and fetched using this steering angle.

In the following step 620, it is determined whether or not the steering state (which is frequently steered) is an unstable correction steering state based on the captured steering angle or steering angular velocity and the vehicle body velocity. That is, as indicated by the diagonal lines in FIG. 16, the frequency (ratio within the predetermined time) of traveling within the region indicated by the vehicle body speed within the predetermined range and the steering angle (or steering angular velocity) within the predetermined range is equal to or greater than the predetermined frequency. When, it is determined that the correction steering state. If an affirmative decision is made here, step 6
30, the process proceeds to step 640 if a negative determination is made.

In step 630, the correction steering state is in effect, so in order to perform more stable steering, a correction amount of an assist amount, which will be described later, is calculated, and the process proceeds to step 640. This correction amount is for reducing the assist amount, and therefore, a method of reducing the assist amount by a fixed amount in one calculation, a method of increasing the assist amount as the vehicle speed increases, and A method of reducing the assist amount by a predetermined amount over a certain period can be adopted.

In step 640, a process for setting the assist amount is performed according to the steering angle or the steering angular velocity using a map as shown in FIG. 17 (a). In particular,
By using a map in which the assist amount decreases as the steering angle or steering angular velocity increases, the steering force becomes heavier as the steering angle or steering angular velocity increases, and steering stability and steering feeling are improved. Further, here, the assist amount is set according to the vehicle body speed using a map of different tendencies such as a high speed region, a medium speed region, and a low speed region. Specifically, each map is set so that the assist amount becomes smaller as the vehicle speed increases. Apart from this, as shown in FIG. 17 (b),
The assist amount may be set using a three-dimensional map including the steering angle or the steering angular velocity, the vehicle body speed, and the assist amount.

Furthermore, when the correction amount is calculated in step 630, the correction amount is subtracted from the assist amount set as described above. In the following step 640, the calculated assist amount is output to perform the assist control, and the present process is temporarily ended.

As described above, in this processing, the assist amount is decreased as the vehicle speed and the steering angle (or the steering angular velocity) are increased, so that the steering stability in an unstable state such as turning or lane change can be obtained. The steering feeling can be improved. In addition, in this processing, the correction steering state is learned, and when it is determined from the steering frequency that the correction steering state is in effect, the correction amount is corrected so as to be decreased. Therefore, for example, mountain road traveling and rut road traveling. It is possible to improve steering stability and steering feeling in an unstable state such as a side wind disturbance.

(6) Control during acceleration As shown in FIG. 18, in this process, in step 700,
The wheel speed of each wheel is fetched based on the signal from the wheel speed sensor 7.

In the following step 705, the vehicle speed is calculated using the fetched wheel speed in the same manner as in step 210 described above. In the following step 710, the engine rotation speed is fetched based on the signal from the engine rotation speed sensor 9.

In the following step 720, the engine rotation acceleration is calculated using the fetched engine rotation speed. In the following step 730, a process for setting the assist amount is performed based on the calculated engine rotation acceleration using a map as shown in FIG. Specifically, by using a map in which the assist amount decreases as the engine rotation acceleration increases, the steering force becomes heavier as the acceleration state becomes more significant (that is, the engine rotation acceleration increases), and the steering stability is increased. And improve steering feeling. Further, here, the assist amount is set according to the vehicle body speed using a map of different tendencies such as a high speed region, a medium speed region, and a low speed region.
Specifically, each map is set so that the assist amount becomes smaller as the vehicle speed increases.

Apart from this, as shown in FIG. 19B, the assist amount may be set using a three-dimensional map of engine rotational acceleration, vehicle speed and assist amount. In the following step 740, the calculated assist amount is output to perform the assist control, and the present processing is temporarily ended.

As described above, in this processing, the assist amount is reduced as the engine rotational acceleration increases, so that the steering stability and steering feeling in an unstable state such as during acceleration can be improved. . Further, in this processing, not only the engine rotation acceleration but also the vehicle body speed is taken into consideration, and the assist amount is reduced as the engine rotation acceleration and the vehicle body speed increase, so that the steering stability and steering feeling can be further improved. .

(7) Control during acceleration and deceleration (No. 1) As shown in FIG. 20, in this process, in step 800,
The wheel speed of each wheel is fetched based on the signal from the wheel speed sensor 7.

In the following step 810, the vehicle speed is calculated using the fetched wheel speed in the same manner as in step 210 described above. In the following step 820, the vehicle body longitudinal velocity which is the longitudinal acceleration (acceleration or deceleration) of the vehicle body is calculated using this vehicle body speed.

In the following step 830, the assist amount is set based on the vehicle body longitudinal acceleration. In particular,
As shown in FIG. 21A, by using a map in which the assist amount decreases as the vehicle longitudinal acceleration increases, the steering force is increased as the acceleration or deceleration state becomes more significant (that is, the vehicle longitudinal acceleration increases). It is made heavier to improve steering stability and steering feeling. Further, here, the assist amount is set according to the vehicle body speed using a map of different tendencies such as a high speed region, a medium speed region, and a low speed region. Specifically, each map is set so that the assist amount becomes smaller as the vehicle speed increases.

Apart from this, as shown in FIG. 21 (b), the assist amount may be set using a three-dimensional map of vehicle longitudinal acceleration, vehicle speed and assist amount. In the following step 840, the calculated assist amount is output to carry out the assist control, and the present processing is temporarily ended.

As described above, in this processing, the assist amount decreases as the vehicle longitudinal acceleration (absolute value) increases, so that the steering stability and steering feel in an unstable state such as during acceleration or deceleration are increased. The ring can be improved. Further, in this processing, not only the longitudinal acceleration of the vehicle body but also the vehicle body speed is taken into consideration, and the assist amount is decreased as the vehicle body longitudinal acceleration and the vehicle speed increase, so that the steering stability and the steering feeling can be further improved. .

In the case of this processing, it may be executed only at a speed lower than a predetermined vehicle speed. This is because an unstable state such as pitching is likely to occur due to a sudden torque change or the like at a low speed, so that such a state is appropriately dealt with.

(8) Control during acceleration and deceleration (part 2) As shown in FIG. 22, in this processing, in step 900,
The wheel speed of each wheel is fetched based on the signal from the wheel speed sensor 7.

In the following step 910, the vehicle speed is calculated using the fetched wheel speed in the same manner as in step 210 described above. In the following step 910, the temporal change rate of the average value of the left and right wheel speeds is calculated using the wheel speeds fetched in step 900.

In the following step 920, the assist amount is set based on the temporal change rate of the average value of the left and right wheel speeds. Specifically, as shown in FIG. 23A, by using a map in which the assist amount decreases as the change rate increases, the acceleration or deceleration state becomes more significant (that is, the change rate increases. ) Increase the steering stability and steering feel by increasing the steering force.
Further, here, the assist amount is set according to the vehicle body speed using a map of different tendencies such as a high speed region, a medium speed region, and a low speed region. Specifically, each map is set so that the assist amount becomes smaller as the vehicle speed increases.

Alternatively, as shown in FIG. 23 (b), the assist amount may be set using a three-dimensional map consisting of the rate of change, the vehicle speed and the assist amount. In the following step 940, the calculated assist amount is output to perform the assist control, and the present process is once ended.

As described above, in this processing, the assist amount is reduced as the temporal change rate of the average value of the left and right wheel speeds is increased, so that the steering operation in an unstable state such as during acceleration or deceleration is performed. It is possible to improve stability and steering feeling. Further, in the present processing, not only the change rate but also the vehicle body speed is taken into consideration, and the assist amount is reduced as the change rate and the vehicle body speed increase, so that the steering stability and steering feeling can be further improved.

In the case of this processing, it may be executed only at a predetermined vehicle body speed or higher. This is because it is not necessary to give a comparative importance to steering stability in the low speed range, and operability is facilitated.

(9) Composite Control with Suspension Control (1) As shown in FIG. 24, in this processing, in step 1000, the wheel speed of each wheel is fetched based on the signal from the wheel speed sensor 7.

In the following step 1010, the vehicle speed is calculated using the fetched wheel speed in the same manner as in step 210 described above. In the following step 1020, the sensors required for various suspension stiffness controls (vehicle speed response control, anti-roll control, anti-dive control, anti-scoot control, pitch, bounce suppression control) shown in Tables 2 and 3 below are used. It takes in signals and performs necessary calculations. Specifically, Table 2 below
As shown in, for example, the steering angle, the steering angular velocity, the engine rotation speed, the engine rotation acceleration, the stop lamp SW2.
1, lateral G, yaw rate, up / down G, and a height sensor (not shown) such as relative displacement between the wheel and the vehicle body are taken in.

In the following step 1030, it is necessary (by changing the orifice area of the shock absorber) to carry out suspension rigidity control as shown in Tables 2 and 3 below, based on the respective fetched data. Set the target damping force.

[0075]

[Table 2]

[0076]

[Table 3] In the following step 1040, the assist amount is set based on this target damping force. Specifically, FIG. 25 (a)
As shown in, by using a map in which the assist amount decreases as the target damping force increases, the steering force increases as the target damping force increases. As a result, the suspension rigidity control and the power steering control act in combination to further improve the steering stability and steering feeling.

As shown in FIG. 25 (b), a three-dimensional map consisting of the target damping force, the vehicle body speed, and the assist amount is used to calculate not only the target damping force but also the assist amount as the vehicle speed increases. May be set so that becomes smaller. In the following step 1050, the calculated assist amount is output to perform the assist control, and the present process is once ended.

As described above, in this processing, the assist amount is reduced as the target damping force in various suspension stiffness control increases, so that the steering stability and steering feeling are further improved than the control in which the power steering control is simply performed. Can be improved.

Further, in this processing, not only the target damping force but also the vehicle body speed is taken into consideration, and the assist amount is reduced as the target damping force and the vehicle body speed increase, so that the steering stability and steering feeling are further improved. can do. still,
In this processing, the suspension damping control was performed by calculating the target damping force, but apart from this, the target value of the spring constant of the air spring, the target value of the hydraulic stabilizer control, the target value of the vehicle height control, etc. It may be calculated and the control may be performed using this as the rigidity target value.

(10) Composite Control with Suspension Control (Part 2) As shown in FIG. 26, in this processing, in step 1100, the wheel speed of each wheel is fetched based on the signal from the wheel speed sensor 7.

In the following step 1110, the vehicle speed is calculated using the fetched wheel speed in the same manner as in step 210 described above. In the following step 1120, data indicating whether the current suspension setting mode is the (soft eye) normal mode or the (soft eye) sports mode is fetched based on the signal from the mode switching SW 23.

In the following step 1130, the assist amount is set based on the state of this mode and the vehicle speed.
Specifically, as shown in FIG. 27A, in both the normal mode and the sports mode, the assist amount is set to become smaller as the vehicle speed increases.
In the sports mode, the assist amount is set lower than in the normal mode. That is, the steering force is set to be heavier in the sports mode. As a result, the suspension rigidity control and the power steering control act in combination to further improve the steering stability and steering feeling.

As shown in FIG. 27 (b), the three-dimensional map of the target damping force, the vehicle body speed and the assist amount described above is used to determine not only the mode but also the target damping force and the vehicle body speed. It may be set such that the larger the amount, the smaller the assist amount. In the following step 1140, the calculated assist amount is output to perform the assist control, and the present process is temporarily ended.

As described above, in this processing, the mode switching SW2
Since the assist amount is adjusted according to the operation state of 3,
It is possible to further improve the steering stability and the steering feeling as compared with the case where the power steering control is simply performed. In this process, not only the state of the mode,
The target damping force and the vehicle body speed are also taken into consideration, and the assist amount is reduced as the target damping force and the vehicle body speed increase, so that the steering stability and steering feeling can be further improved.

In this process, the target damping force is calculated and the suspension rigidity control is performed. However, in addition to this, the target value of the spring constant of the air spring, the target value of the control of the hydraulic stabilizer, or the vehicle height control is performed. It is also possible to calculate the target value and the like, and use this as the rigidity target value for control.

(11) Combined control with suspension control depending on the tilting state and unsprung flapping state of the vehicle As shown in FIG. 28, in this process, in step 1200, based on the signal from the wheel speed sensor 7. Take the wheel speed of each wheel.

In the following step 1210, the vehicle body speed is calculated based on this wheel speed. Continued Step 122
At 0, similar to step 310 described above, a resonance frequency component on the spring (for example, 1 Hz to 2 Hz) or a resonance frequency component on the unsprung (for example, 10 Hz to 20 Hz) is used from the fluctuation of the wheel speed by using a frequency filter. To extract.
Here, when the resonance frequency component on the spring is 1 Hz to 2 Hz, the vehicle is in a fluffy state, while when the resonance frequency component under the spring is 10 Hz to 20 Hz, the vehicle is flapping ( It is not preferable because the vehicle is unstable. Either one of the resonant frequency component on the spring and the resonant frequency component on the unsprung component may be extracted, or both may be extracted.

In the following step 1230, in order to perform suitable vehicle control relating to suspension rigidity control, that is, in accordance with the extracted sprung or lower resonance frequency component, that is,
A rigidity target value that suppresses flapping and flapping is calculated. Specifically, for example, the target damping force of the shock absorber is calculated.

In the following step 1240, a control signal based on the calculated target damping force is output to the damping force switching actuator 29. In the following step 1250, the assist amount is set based on this target damping force. Specifically, using a map as shown in FIG. 29A, the assist amount is set to be smaller as the target damping force is larger. As a result, the suspension rigidity control and the power steering control act in combination to further improve the steering stability and steering feeling.

As shown in FIG. 29B, a three-dimensional map of target damping force, vehicle speed and assist amount is used to decrease the assist amount as the target damping force and vehicle speed increase. You may set it like this. In the following step 1260, the calculated assist amount is output to perform the assist control, and the present process is temporarily ended.

As described above, in this processing, the resonance frequency components of the sprung / under spring are extracted, the target damping force is set so as to suppress the flapping and the fluttering, and the suspension rigidity is controlled. Since the assist amount is adjusted in accordance with the above, it is possible to further improve the steering stability and the steering feeling as compared with the control in which the power steering control is simply performed.

Further, in this process, not only the target damping force but also the vehicle speed is taken into consideration, and the assist amount is reduced as the vehicle speed increases, so that the steering stability and steering feeling can be further improved. it can. In this process,
Although the suspension damping control was performed by calculating the target damping force, apart from this, the target value of the spring constant of the air spring, the target value of the control of the hydraulic stabilizer, or the target value of the vehicle height control, etc. were calculated, and The control may be performed with the rigidity target value as.

(12) Composite Control with Suspension Control According to Steering State As shown in FIG. 30, in this processing, in step 1300, the wheel speed of each wheel is fetched based on the signal from the wheel speed sensor 7. .

In the following step 1310, the vehicle body speed is calculated based on this wheel speed. Continued Step 132
At 0, the steering angle is acquired based on the signal from the steering angle sensor 13 as in step 120 described above.
The steering angle may be used to calculate and capture the angular velocity.

In the following step 1330, instability is performed in order to perform a suitable vehicle control relating to suspension stiffness control, that is, when the steering is made large or abruptly according to the taken steering angle and / or the steering angular velocity. A stiffness target value that suppresses various vehicle movements is calculated. Specifically, for example, the target damping force of the shock absorber is calculated.

At the following step 1340, a control signal based on the calculated target damping force is output to the damping force switching actuator 29. In the following step 1350, the assist amount is set based on this target damping force. Specifically, using a map as shown in FIG. 31A, the assist amount is set to be smaller as the target damping force becomes larger. As a result, the suspension rigidity control and the power steering control act in combination to further improve the steering stability and steering feeling.

As shown in FIG. 31B, a three-dimensional map of target damping force, vehicle speed and assist amount is used to decrease the assist amount as the target damping force and vehicle speed increase. You may set it like this. In the following step 1360, the calculated assist amount is output to perform the assist control, and the present process is temporarily ended.

As described above, in this processing, the target damping force is set based on the steering angle and / or the steering angular velocity to perform suspension rigidity control, and the assist amount is adjusted according to the target damping force. Therefore, for example, when turning or when changing lanes, the steering stability and the steering feeling can be further improved as compared with the case where the power steering control is simply performed.

Further, in this processing, not only the target damping force but also the vehicle speed is taken into consideration, and the assist amount is reduced as the vehicle speed increases, so that the steering stability and steering feeling can be further improved. it can. In this process,
Although the suspension damping control was performed by calculating the target damping force, apart from this, the target value of the spring constant of the air spring, the target value of the control of the hydraulic stabilizer, or the target value of the vehicle height control, etc. were calculated, and The control may be performed with the rigidity target value as.

(13) Composite Control with Suspension Control According to Steering State As shown in FIG. 32, in this processing, in step 1400, the wheel speed of each wheel is fetched based on the signal from the wheel speed sensor 7. .

In the following step 1410, the vehicle body speed is calculated based on this wheel speed. Continued Step 141
In 5, the engine rotation speed is fetched based on the signal from the engine rotation speed sensor 9. Following Step 1420
Then, the engine rotation acceleration is calculated based on the engine rotation speed.

In the following step 1430, the signal from the stop lamp SW21 is fetched in order to detect the braking operation. In subsequent step 1440, the engine rotational acceleration is used to estimate the vehicle body longitudinal acceleration, which is the acceleration (acceleration or deceleration) in the vehicle longitudinal direction. Here, instead of using the engine rotation acceleration, the vehicle body longitudinal velocity may be obtained using the vehicle body speed in the same manner as in step 820 described above.

In the following step 1450, in order to perform suitable vehicle control relating to suspension rigidity control in accordance with the vehicle body longitudinal acceleration and the state of the stop lamp SW21, that is, instability when sudden acceleration or sudden braking is performed. A stiffness target value that suppresses various vehicle movements is calculated.
Specifically, for example, the target damping force of the shock absorber is calculated.

In the following step 1460, a control signal based on the calculated target damping force is output to the damping force switching actuator 29. In the following step 1470, the assist amount is set based on this target damping force. Specifically, using a map as shown in FIG. 33A, the assist amount is set to be smaller as the target damping force is larger. As a result, the suspension rigidity control and the power steering control act in combination to further improve the steering stability and steering feeling.

As shown in FIG. 33 (b), the assist amount decreases as the target damping force and the vehicle speed increase by using a three-dimensional map of the target damping force, the vehicle speed and the assist amount. You may set it like this. In the following step 1480, the calculated assist amount is output to perform the assist control, and the present process is temporarily ended.

As described above, in this processing, the suspension damping control is performed by setting the target damping force based on the longitudinal acceleration of the vehicle body and the state of the stop lamp SW21.
Since the assist amount is adjusted according to the target damping force, it is possible to further improve the steering stability and the steering feeling, for example, in the case of sudden acceleration or sudden braking, compared to the control in which only power steering control is performed. it can.

Further, in this processing, not only the target damping force but also the vehicle speed is taken into consideration, and the assist amount is reduced as the vehicle speed increases, so that the steering stability and steering feeling can be further improved. it can. In this process,
Although the suspension damping control was performed by calculating the target damping force, apart from this, the target value of the spring constant of the air spring, the target value of the control of the hydraulic stabilizer, or the target value of the vehicle height control, etc. were calculated, and The control may be performed with the rigidity target value as.

(14) Control when the wheel speed sensor is disconnected As shown in FIG. 34, in this process, in step 1500, the wheel speed of each wheel is fetched based on the signal from the wheel speed sensor 7.

In the following step 1510, the disconnection state of the wheel speed sensor 7 is detected as shown in Table 4 below.

[0110]

[Table 4] In the following step 1520, it is determined whether or not there is a wire break. If it is judged that the wire breaks, the process proceeds to step 1530. If it is judged that the wire has not broken, the process proceeds to step 1540. In step 1530, the vehicle body speed is calculated according to the normal wheel speed of the wheel as shown in Table 5 below.

[0111]

[Table 5] On the other hand, in step 1540, the vehicle body speed is calculated from the information of all the wheels. In the following step 1550, the assist amount is set according to the calculated vehicle speed. In the following step 1560, the calculated assist amount is output and the assist control is performed, and the present process is temporarily ended.

Thus, in this processing, the wheel speed sensor 7
Is detected, the accurate vehicle body speed is calculated based on the output from the normal wheel speed sensor 7, and the power steering can be controlled appropriately. Further, since a plurality of wheel speeds are detected and used, there is an effect that the redundancy of the system is increased and the reliability is improved.

The present invention is not limited to the above-mentioned embodiments, and it goes without saying that the present invention can be implemented in various modes within the scope of the gist of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating the configuration of the invention of claim 1.

FIG. 2 is an explanatory diagram showing a hardware configuration of an example of the present invention.

FIG. 3 is a block diagram showing an electrical configuration of the embodiment.

FIG. 4 is a flowchart showing the basic processing of the embodiment.

FIG. 5 is a flowchart showing a process using (1) wheel speed.

FIG. 6 is a graph showing the relationship between the assist amount and the vehicle body speed in the process (1).

FIG. 7 is a graph showing another relationship between the assist amount of the process (1) and the vehicle body speed.

FIG. 8 is a flowchart showing a process using the resonance frequency component of (2).

FIG. 9 is a graph showing a relationship between an assist amount of the process (2) and a resonance frequency component.

FIG. 10 is a graph illustrating the relationship between the amount of assistance in the process (2) and the resonance frequency component.

FIG. 11 is a flowchart showing the processing using (3) lateral G and the like.

FIG. 12 is a graph showing the relationship between the assist amount and the lateral G in the process (3).

FIG. 13 is a flowchart showing a process (4) using the left and right wheel speed differences.

FIG. 14 is a graph showing the relationship between the assist amount of the process (4) and the left and right wheel speed differences.

FIG. 15 is a flowchart showing a process according to a steering state of (5).

FIG. 16 is a graph showing a corrected steering state in the process (5).

FIG. 17 is a graph showing the relationship between the assist amount in the process (5), the steering state, and the vehicle body speed.

FIG. 18 is a flowchart showing a process using (6) engine rotational acceleration.

FIG. 19 is a graph showing the relationship between the assist amount of the process (6), the engine rotation acceleration, and the vehicle body speed.

FIG. 20 is a flowchart showing a process using (7) vehicle body longitudinal acceleration.

FIG. 21 is a graph showing the relationship between the assist amount of the process (7), vehicle longitudinal acceleration, and vehicle speed.

FIG. 22 is a flow chart showing the process (8) using the change rate of the average value of the left and right wheel speeds.

FIG. 23 is a graph showing the relationship between the vehicle speed and the rate of change in the average value of the left and right wheel speeds in the process (8).

FIG. 24 is a flowchart showing a process using a target damping force of suspension control in (9).

FIG. 25 is a graph showing the relationship between the assist amount and the target damping force and the graph (b) showing the relationship between the assist amount, the target damping force, and the vehicle body speed in the process of (9).

FIG. 26 is a flowchart showing the processing using the mode switching SW of (10).

FIG. 27 is a graph showing the relationship between the assist amount, the mode and the vehicle body speed in the process (10), and the graph showing the relationship between the assist amount, the target damping force and the vehicle body speed. .

FIG. 28 is a flowchart showing the processing (11) using the resonance frequency component and the target damping force.

29 is a graph showing the relationship between the assist amount and the target damping force, and FIG. 29 (b) is a graph showing the relationship between the assist amount, the target damping force and the vehicle body speed in the process of (11).

FIG. 30 is a flowchart showing a process using (12) the steering state and the target damping force.

FIG. 31A is a graph showing the relationship between the assist amount and the target damping force, and FIG. 31B is a graph showing the relationship between the assist amount, the target damping force and the vehicle body speed in the process of (12).

FIG. 32 is a flowchart showing a process using (13) acceleration or the like and a target damping force.

33 is a graph showing the relationship between the assist amount and the target damping force, and FIG. 33 (b) is a graph showing the relationship between the assist amount, the target damping force and the vehicle speed in the process of (13).

FIG. 34 is a flowchart showing the processing when (14) an abnormality of the sensor is detected.

[Explanation of symbols]

1 ... Electronic control unit (ECU) 3 ... Power steering 5 ... Shock absorber 7 ... Wheel speed sensor 9 ... Engine speed sensor 13 ... Steering angle sensor 15 ... Vertical G sensor) 17 ... Horizontal G sensor 19 ... Corrate sensor 21 ... Stop lamp SW 23 ... Mode switching SW 25 ... Hydraulic motor 29 ... Damping force actuator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI theme code (reference) B62D 131: 00 B62D 131: 00 (72) Inventor Noriyuki Sakai 1-chome Showa-cho, Kariya city, Aichi Prefecture Stock Association F term in company DENSO (reference) 3D032 CC02 CC08 DA03 DA09 DA24 DA29 DA33 DA43 DA49 DA82 DA93 DB09 DB10 DD01 DD02 EB11 EB22 FF03

Claims (2)

[Claims] 1. A power steering apparatus for adjusting an assist amount, which is an auxiliary steering force applied to a steering wheel, based on a wheel speed detecting means for detecting a wheel speed and a variation state of the wheel speed detected by the wheel speed detecting means. A sprung resonance frequency extracting means for extracting a sprung resonance frequency component; and an assist amount setting means for setting an assist amount for power steering based on the sprung resonance frequency component extracted by the sprung resonance frequency extracting means, A power steering device comprising: 2. The power steering apparatus according to claim 2, wherein the assist amount of the power steering is reduced as the sprung resonance frequency component increases.