JPH069980B2 - Steering force control device for power steering device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a steering force control device that controls the steering force of a power steering device according to the running state of an automobile.

<Prior Art> Conventionally, it is usual to determine the running state of an automobile based on the vehicle speed. Based on the result of this determination, for example, the steering force is light in the low speed range and heavy in the high speed range. Controls the assisting force of the taker.

<Problems to be Solved by the Invention> In the conventional technique for determining the traveling state based on the vehicle speed as described above, the control pattern of the assist force with respect to the vehicle speed, the steering angle, and the like becomes constant, and both in the case of mountain road traveling and in the city area traveling. The control pattern of the assist force does not change, and there is a problem that the steering force suitable for each traveling state cannot be obtained.

In order to solve this, a method has been developed in which a plurality of control patterns for assisting force are provided in the steering force control, and the control pattern is selected by manually switching the changeover switch according to the driver's preference or traveling state.

However, in such a selection method, the driver has to operate the changeover switch frequently, which is very troublesome, and there is a problem that the change in the steering force due to the change is large. In addition, even in mountain road driving and city driving, the running state is not unique, so there is a problem that the optimum steering force control cannot be performed according to the running state.

<Means for Solving Problems> The present invention is designed to automatically perform optimum steering force control according to a traveling state, and the configuration stores a control pattern in which a current characteristic with respect to a steering angle is programmed. Memory means for detecting the frequency at which the steering angle is in the middle steering angle range, and an arithmetic means for calculating an index according to the traveling state of city traveling or mountain road traveling based on this frequency, and the steering angle from the control pattern. Output current calculation means for calculating the output current value according to the traveling state of city running or mountain road by calculating the current value read according to the above and the index, and the output current calculating means And a control means for changing the steering force based on the output current value.

The control pattern stored in the storage means may be one for traveling in urban areas and for traveling on mountain roads.

The output current calculation means calculates an output current value according to an index, and adds, subtracts, or multiplies the current value read according to the steering angle from the control pattern and the index,
The output current value corresponding to the index is calculated by division.

<Operation> When the current value is read from the control pattern in accordance with the steering angle according to the above configuration, an index indicating the traveling state is calculated for this current value, and an output current value corresponding to the index is calculated. The steering force is controlled based on this output current value, and is controlled to a steering force suitable for city driving or mountain road driving.

<Examples> Examples of the present invention will be described below with reference to the drawings. In FIG. 1, a power steering apparatus 10 includes a servo valve 11 connected to a steering handle 18 via a handle shaft 18a.
And a power cylinder 12 connected to the steered wheels via a link mechanism (not shown). If a manual steering torque is applied to the steering handle 18 as is known, the power cylinder 12
The steering torque increased by is transmitted to the steered wheels. The drive belt 1 is attached to the power steering apparatus 10.
A pressure fluid is supplied by a pump 15 connected to the vehicle engine via 7.

The electromagnetic valve 20 controls the assist force by the power cylinder 12 by bypassing between the two chambers of the power cylinder 12 to which the pressure fluid is selectively supplied from the pump 15 via the servo valve 11, and is shown in FIG. So, the valve body 2
Spool 23 slidably fitted in the inner hole 22
And a solenoid 24. The spool 23 is normally held at the lower end by a spring 25, and blocks the passages 26 and 27 communicating with both chambers of the power cylinder 12 from each other. Then, when the solenoid 24 is energized, the spool 23 is attracted in accordance with the current value and is displaced upwards against the spring 25, so that the passages 26 and 27 are communicated with each other through the bypass slit 28. It As a result, the assist force (steering force) of the power steering apparatus 10 is changed.

In FIG. 1, reference numeral 50 is an electronic control unit. The electronic control unit 50 has a microprocessor 51, a writable memory (hereinafter simply referred to as RAM) 52, and a read-only memory (hereinafter simply referred to as ROM) 53 as main components,
An interface 60 and a solenoid drive circuit 61 are connected to the microprocessor 51 so as to control the current applied to the solenoid 24 of the solenoid valve 20. A steering angle sensor 40 is connected to the microprocessor 51 via an interface 47 and a phase determination circuit 45. The steering angle sensor 40 includes a rotating plate 41 fixed on the handle shaft 18a and two photo interrupters 42 and 43. The steering angle θ is detected by signals from the photo interrupters 42 and 43. . Further microprocessor 5
A vehicle speed sensor 46 is connected to the vehicle 1 via an interface 47. The vehicle speed sensor 46 is composed of a tachometer connected to the output shaft of the transmission, and detects the vehicle speed by the frequency of the pulse signal generated by the vehicle speed sensor 46.

On the other hand, the ROM 53 stores a control pattern I for driving in urban areas as a characteristic map. As shown in FIG. 3, this control pattern I is programmed with the change characteristic of the current value i to be applied to the solenoid 24 with respect to the steering angle θ of the steering wheel. As an example of this change characteristic, when the steering angle is 0 (when the steering is neutral), the current value is 0, and the steering angle θ
Is set so that the current value gradually increases as is increased.

The RAM 52 has a storage area for storing the frequency corresponding to the steering angle θ of the steering wheel, and the ROM 53 calculates an index K indicating the traveling state, and the solenoid valve 2 is calculated according to the index K.
A control program for calculating the applied current to 0 is stored.

FIGS. 4 and 5 show the frequency distribution corresponding to the steering angle θ. In mountain road driving, there are many curves, but there are few turns at right angles, so the frequency distribution is as shown in FIG. 4 and in urban driving. There are many straight roads and few curves, but many turns at right angles at intersections, so the frequency distribution is as shown in Fig. 5. Therefore, the index K (hereinafter referred to as mountain road index) K obtained by the execution of the control program is larger when traveling on mountain roads than when traveling on urban areas.

Next, an example of determining the running state will be described with reference to the flowchart shown in FIG.

In the traveling state of the vehicle, the steering angle signal θ detected by the steering angle sensor 40, which changes momentarily, is detected by the phase determination circuit 4
A vehicle speed signal detected by the vehicle speed sensor 46 is also input to the counter (not shown) via the counter 5.

The microprocessor 51 executes a processing operation based on a program at the same time when an interrupt signal is input for each predetermined traveling distance. First, the steering angle θ stored in the counter is read in step 100 of FIG.
1, the sampling number counter value n is the set number N
Compared to. Immediately after the start of running, the number of samplings is small, and since n <N, the program proceeds to step 102, where 1 is added to the sampling number counter value n,
In the following step 103, n in the storage area of the RAM 52
The absolute value of the steering angle θ is set in the th region Mn.

When the number of samples n increases and reaches the set number N, the program proceeds from step 101 to step 104, the set value of the area M2 is set to the area M1, the set value of the area M3 is set to the area M2, ... The absolute value of the latest (nth) steering angle θ is set in the last area M _N , and the stored contents are updated in this manner. In this state, the sampling number counter value remains n (= N).

Step 103 or sampling number counter value to a subsequent read step 105 the counter H 104 n is initialized, the value M _H of first H-th region in the subsequent step 106 is compared to two set values B and C. Here, the set values B and C form the lower limit value and the upper limit value of the medium steering angle range L (corresponding to running on a gentle curve) as shown in FIGS. 4 and 5, and the absolute values are B and C. When the steering angle is in the range between 0 and 1, it is determined that the steering angle is in the middle steering angle range. If B ≦ M _H ≦ C in step 106, step 1
08, and if B ≦ M _H ≦ C, 1 is added to the value D of the frequency counter (initialized to 0 each time it is executed) in step 107, and the process proceeds to step 108, in which the read counter value is read. 1 is subtracted from H. In the following step 109, the read counter value H is compared with the numerical value 0, and the above steps 106 to 108 are repeated until H becomes 0, and when H = 0, the program proceeds to the next step 110. Step 106 above
By repeating steps 108 to 108, the frequency counter value D becomes the frequency number of the values Mn of the respective storage areas where B ≦ Mn ≦ C.

In the following step 110, the mountain road index K is calculated by the following equation.

K = D / n As described above, since the ratio of the frequency D of the middle steering angle range L is small in the city driving, the mountain road index K has a small value, and conversely, the ratio of the frequency D of the middle steering angle range L is the ratio in the mountain traveling. Is large, the mountain road index K becomes a large value, and the running state can be determined based on the size of the index K.

Next, processing for controlling the steering force according to the mountain road index K calculated as described above will be described based on the flowchart of FIG.

First, in step 200, the steering angle θ is read, and then in step 201, the current value i corresponding to the steering angle θ is read from the control pattern I stored in the ROM 53. In the following step 202, the mountain road index K calculated as described above is read. In step 203, the mountain road index K is added to the current value i to calculate the output current value io, and the output current value io is calculated in step 20.
4 and is applied to the solenoid 24 of the solenoid valve 20 to change the assisting force of the power steering apparatus 10.

As a result, in the case of typical urban driving in which the mountain road index K is the minimum value (0), the steering force is controlled lightly by the current characteristics shown by the solid line in FIG. 3, and conversely the mountain road index K is the maximum value. In the case of a typical mountain road traveling, the steering force is controlled to be overweight due to the current characteristics shown by the chain double-dashed line in FIG. 3, and the mountain road index K is the minimum value and the maximum value. In the case of the intermediate value of, the steering force is controlled with the characteristic intermediate between the solid line and the two-dot chain line in FIG. Thus, the steering force can be controlled according to the mountain road index K using one control pattern.

In this case, when calculating the output current value io, the constant A
Can also be used to calculate as io = i + A × K.

In addition, as a control pattern, a characteristic map for mountain road traveling is R
If stored in the OM 53, step 20 in FIG.
3, the mountain road index K is subtracted from the current value i, that is, the output current value io is calculated based on io = i-K or io = i-A × K. Steering force control can be performed.

FIG. 8 and FIG. 9 show another embodiment of the present invention, in which the relationship of the changing characteristics of the current value i between city driving and mountain driving is changed.

That is, in FIG. 8, the current value when the steering angle θ is 0 is the same (0) in the urban driving and the mountain road traveling, and therefore, the change rate of the current value with respect to the change of the steering angle θ is the mountain road traveling. It is designed to be larger in running. Therefore, in the present embodiment, the output current value io may be calculated by multiplying or dividing the current value i read according to the steering angle θ by the mountain road index K.

Further, in FIG. 9, the current value when the steering angle θ is 0 is higher in the case of traveling on a mountain road than in the case of traveling in an urban area, and the rate of change of the current value with respect to the change of the steering angle θ is large. It was done. Therefore, in the case of this embodiment, when the output current value io corresponding to the mountain road index K is calculated from the control pattern I for driving in urban areas, the following formula may be used.

i ₀ = (i + A × K) + (i × B × K) Here, B is a constant different from the constant A.

In the above embodiment, the example in which the steering force is controlled by the bypass control of the power cylinder has been described, but the control of the steering force may take various methods such as reaction force control and pump flow rate control. Regarding the control form,
In addition to the control according to the steering angle described in the embodiment, the control can be performed according to the change of the vehicle speed or the steering angular velocity in addition to the steering angle.

<Effect of the Invention> As described above, according to the present invention, an index is calculated according to the traveling state of city traveling or mountain road traveling based on the frequency at which the steering angle is in the middle steering angle range. Accordingly, the output current value is calculated by calculating the current value read from the control pattern, and the steering force is controlled based on this output current value. Therefore, it is only necessary to store one control pattern. In addition, there is an effect that the optimum steering force control can be performed according to the driving state such as city driving or mountain road driving.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a block diagram showing the entire steering force control device of a power steering device, FIG. 2 is a cross-sectional view showing an electromagnetic valve for bypass control, and FIG. Is a diagram showing a control pattern, FIG. 4 is a diagram showing a frequency distribution of steering angles when traveling on a mountain road, FIG. 5 is a diagram showing a frequency distribution of steering angles when traveling on an urban area, FIG. 6 and FIG. Shows a flow chart, and FIGS. 8 and 9 show another embodiment of the present invention. 10 ... power steering device, 52, 53 ... memory, I ...
Control pattern.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hideo Mizoguchi, 1-1 Asahi-cho, Kariya city, Aichi prefecture Takashi Kamei, examiner, Toyota Koki Co., Ltd. (56) References JP-A-60-107461 (JP, A) JP-A-60-42156 (JP, A) JP-A-54-90726 (JP, A) Actual development Sho-59-125472 (JP, U)

Claims (1)

[Claims] 1. A steering means for controlling a steering force of a power steering apparatus according to an index indicating a traveling state, a storage means for storing a control pattern in which a current characteristic with respect to a steering angle is programmed, and a steering wheel with a medium steering angle. Detecting a frequency within the angular range, and calculating means for calculating an index according to the traveling state such as city traveling or mountain road traveling based on this frequency, and the current value read from the control pattern according to the steering angle and the aforesaid An output current calculation means for calculating an output current value according to a traveling state of city traveling or mountain road traveling by calculating an index and a steering force is changed based on the output current calculated by the output current calculating means. A steering force control device for a power steering device configured by a control means.