JPS6018456A - Control method for power steering device - Google Patents

Abstract

PURPOSE:To have light sense steering as well as facilitate identification of the running conditions by reading the number-of-revolution characteristic of an oil pump optimum for the current running conditions, controlling thereupon the revolving speed of the oil pump, and also providing identification and display of the characteristic selected. CONSTITUTION:While a car is running, a car speed signal given by a speed sensor 5a and a steering signal given by a steering sensor 6 are taken in a control part 3, and if it is judged to be during running, the oil pump number-of- revolutions characteristic optimum for the current running conditions is read from the memory. As the running conditions are used car speed and the transverse acceleration as product of it and the amount of steering. On the basis of the oil pump number-of-revolutions characteristic thus read, the oil pump number-of-revolutions signal for the current car speed under running is read to control the motor 2 for driving the oil pump 2a. The oil pump number-of-revolutions characteristic selected is displayed on a display installed in the neighborhood of the instrument panel.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a control method for a power steering device that allows easy steering regardless of driving conditions.

[Prior art]

In general, the steering resistance of a car tends to increase as the vehicle speed decreases, so if you cancel the steering resistance by using a power steering device that operates an oil pump to circulate oil, even if the vehicle speed is low. Necessary steering can be performed with a small steering force. For this reason, conventional power steering systems have been designed to increase the number of revolutions of the oil pump when the vehicle speed is low, and to reduce the number of revolutions of the oil pump when the vehicle speed increases, allowing for light steering. It is used. When the vehicle speed reaches a speed above which power steering is no longer necessary, the oil pump stops rotating to save energy.

However, on downhill slopes with many sharp curves, large steering resistance occurs even when the vehicle is traveling at a relatively high speed.
Power steering systems using conventional control methods have the disadvantage that the oil pump stops when the vehicle speed exceeds a predetermined speed, requiring a large steering force under such driving conditions.

[Object and structure of the invention]

Therefore, an object of the present invention is to provide a control method for a power steering device that can obtain an optimum oil pump rotational speed according to driving conditions.

In order to achieve such an object, the present invention prepares several types of oil pump rotation speed characteristics that indicate the relationship between oil pump rotation speed and vehicle speed, and selects the optimum oil pump rotation speed characteristic according to driving conditions. , the selected characteristic is identified and displayed. Hereinafter, the present invention will be described in detail using drawings showing embodiments.

〔Example〕

FIG. 1 is a diagram showing the configuration of a power steering device.

In the figure, 1 is the steering section, 2 is the oil pump 2
3 is a control unit, 4 is a selection switch for selecting steering characteristics, 5 is an engine, 5a is a speed sensor, 5b is a starter sensor, 5c is an engine sensor,
6 is a steering sensor, T is an ignition switch, 8 is a battery, and 9 is an alternator. FIG. 2 is a circuit diagram showing these connections. In the figure, the steering sensor 6 is composed of a light emitting diode 6a, a slit disk 6b, and a phototransistor 6c, and is configured to send out a pulse proportional to the amount of steering. The voltage of the battery 8 is sent to the starter sensor 5b when a starter motor (not shown) for starting the engine is operating, and the voltage of the battery 8 is sent to the engine sensor 5c when the engine is operating.

Note that the diode 2b connected in parallel with the motor 2 is a diode for absorbing transient voltage of the motor 2. The control unit 3 includes waveform shaping circuits 30 and 31, oscillation circuits 32 and 33, a frequency division ratio setting circuit 34, an information display 35, a switching circuit 36,
The waveform shaping circuit 30 is composed of a current value judgment circuit 37, control circuits 38, 39, stabilizing circuits 40, 41, 4λ pull-up circuit 43, and a display 44 that displays steering characteristics, and is a NAND circuit with resistors 30a to 30d. 3
The waveform shaping circuit 31 includes resistors 31a, 3lb, a diode 31c1, and NAND circuits 31d and 31e. Oscillation circuit 3
2 is a resistor 32m, 32b, a capacitor 32c, 32
The oscillation circuit 33 includes a resistor 33a, capacitors 33c and 33d, and a ceramic oscillator 33e. The frequency division ratio setting circuit 34 includes resistors 34a to 34c1 and switches 348 to 341.
Since the number of pulses per unit traveling distance generated from the speed sensor 5a may differ depending on the type of vehicle, the frequency division built into the control circuit 39 can be adjusted by appropriately setting the switches 348 to 34f. The division ratio of the circuit is controlled so that the number of pulses per unit traveling distance sent from the terminal 39a does not vary depending on the vehicle type.

The alarm indicator 35 is composed of a resistor 35a and a light emitting diode 35b. The switching circuit 36 is composed of resistors 36a to 36f and transistors 362 and 36h. The current value setting circuit 31 includes resistors 37a to 37m.
1 capacitor 37p1 amplifier 37q1 comparator 37
r to 37t, and determines which of the predetermined 3wi setting values the current flowing through the motor 2 exceeds. The control circuit 38 is connected to the terminal 38
The processing described below is performed based on the signals supplied to terminals a to 38k, and a 5-bit parallel signal corresponding to the input signal is sent to terminal 3.
In addition to outputting multiple signals from 8t to 38q, an alarm signal reset signal is sent from terminals 38r and 38s at necessary times, and a zero level signal for displaying steering characteristics is sent to any one of terminals 38t to 38W. It looks like this. As described above, the control circuit 39 has terminals 39b to 39d.
The signal supplied to the terminal 39e is frequency-divided at a division ratio according to the signal supplied to the terminal 39e and outputted to the terminal 39a, and when a signal is supplied to the terminal 39f, reset control is performed and the signal is supplied to the terminal 391. When this occurs, a zero level signal is sent to the terminals 39h to 39z, and a signal whose duty ratio changes according to the signals supplied to the terminals 39m to 39tr is sent to the terminals 39t to 39W. The stabilizing circuits 40 to 42 stabilize the supplied voltage to 5 volts and output it, and the stabilizing circuit 41 has a resistor 4.
1at41b, a capacitor 41c1, and a Zener diode 41d, and the stabilizing circuit 42 includes a resistor 42a,
42b, capacitor 42c1 Zener diode 42d
It consists of Pull-up circuit 43 expansion resistor 43a
43d. The indicator 44 is a resistor 44
a to 44d and light emitting diodes 440 to 44h, and display the steering characteristic automatically selected by the switch 4 or the control circuit 38. Note that the control circuit 38 is configured to preferentially display the steering characteristics determined by the switch 4. As described above, in the present invention, the optimum oil pump rotation speed characteristics are selected according to the driving conditions. , the lateral acceleration obtained by multiplying the vehicle speed and the amount of steering is used as the driving condition. FIGS. 3(a) and 3(b) are graphs showing the results of counting the number of vehicle speed pulses for 3 seconds and the results of counting the number of steering pulses for 3 seconds at each running point. 1. It is assumed that the vehicle speed pulse is proportional to the speed per hour, and the steering pulse is output as a pulse proportional to the steering angle.

The oil pump rotation speed characteristics are read out according to the lateral acceleration and vehicle speed determined at predetermined intervals, but if this period is too long, it may not match the actual situation, and if it is too short, the rotation speed characteristics may change frequently. Since it gives a strange feeling to the steering, a period of about 30 seconds is appropriate. The lateral acceleration is determined as the product of the vehicle speed and the amount of steering, but if the vehicle speed and the amount of steering are used by accumulating data generated over 30 seconds, problems may occur.

For example, if the vehicle speed is the cumulative value of vehicle speed pulses for 30 seconds and the steering amount is the cumulative value of steering pulses for 30 seconds, range A in Figure 3 is used.
Adding the vehicle speed, steering amount, and lateral acceleration during the period shown in , the result is as follows.

Car speed = 4oxs! +toxa+5oxz+aoxa
=80+30+100+90=300 Steering amount=200X2+OX2+150X2+OX2+1
00×2:400+0+300+0+200 =900 Lateral acceleration=300×900=27'0000Similarly, the vehicle speed, steering amount, and lateral acceleration for the period shown in range B in FIG. 3 are calculated as follows.

Vehicle speed = 30 x 6 + 20 x 2 + 40 x 2 = 30° Steering amount = 100 x 6 + 50 x 2 + 200 x 1 = 900 Lateral acceleration = 300 Since we used the cumulative value of the generated data, the lateral acceleration would be the same value,
Even though the driving conditions are different, it becomes impossible to distinguish between them. This is because differences in lateral acceleration due to differences in vehicle speed and distribution of steering events are not taken into consideration, as is clear from the fact that lateral acceleration does not occur when steering is not performed. This is determined by multiplying the short-time vehicle speed and short-time steering amount determined every 3 seconds, which is a sufficiently short period of 30 seconds, to determine the short-time lateral acceleration, and then cumulating this short-time lateral acceleration for 30 seconds to determine the short-time lateral acceleration. If we use time lateral acceleration, it reflects the difference in the distribution of vehicle speed and steering occurrence,
It becomes possible to identify the driving state.

In order to calculate the long-term lateral acceleration for periods A and B in Figure 3, if we include the vehicle speed, steering amount, and short-term lateral acceleration every 3 seconds, we get the results shown in Table 1. If we subtract the long-term lateral acceleration during the period of range A from the results, we get the following.

Long-term lateral acceleration = 8000X2+1500X1+750
0X1+3000X2=31000 In the same way, long-term lateral acceleration during the period of range B is calculated as follows.

Long-term lateral acceleration = 3000x4 + 1500x2 + 400
0x2 + 2000X1=25000 Therefore, since the long-term lateral acceleration is different between the period of range A and the period of range B, it is possible to identify the driving state.

On the other hand, there are four types of oil pump rotational speed characteristics, as shown in FIGS. 4(&) to (d), depending on the type of road.

For example, when driving in an urban area with many narrow one-way streets, there are many opportunities to turn, so the oil pump 2 & should continue to rotate up to about 35 H, which is considered the floor height vehicle speed when driving in an urban area. The characteristics shown in FIG. 4 (&) are suitable. Since the vehicle speed is higher when driving on a general road than when driving in a city, the characteristics shown in Figure 4 (b) are suitable, and when driving on a mountain road with a downward slope, the speed is faster than when driving on a general road. Although the vehicle speed also increases, it is necessary to operate the power steering up to a high vehicle speed, so the characteristics shown in FIG. 4(c) are suitable. On the other hand, when driving at high speed on a highway, the rotation of the oil pump 2 is stopped because power steering is not required, but the power steering is stopped very naturally when transitioning from medium speed to high speed. ,
A characteristic in which the minimum rotational speed of the oil pump 4 immediately before stopping as shown in FIG. 4(d) is small is suitable. Therefore, characteristics suitable for each driving condition may be stored in advance in a memory as shown in FIG. 5, and these characteristics may be read out as needed. In Figure 5, the horizontal axis is 3
The long-term vehicle speed is the average vehicle speed for 0 seconds, and the vertical axis is the long-term lateral acceleration.

In the device configured in this way, one type of oil pump rotational speed characteristic suitable for the driving conditions is read out, and the rotational speed of the oil pump 2a is controlled according to the characteristics and according to the vehicle speed at the time of driving. Ru. Therefore, even when the vehicle is traveling at a relatively high speed on a downhill slope with many sharp curves, the oil pump rotation speed characteristic suitable for the traveling conditions is read out, so that light steering can be performed.

The oil pump rotational speed characteristic selected in this manner is identified and displayed on a display 44 shown in FIG. The display 44 is mounted, for example, near the instrument panel for easy viewing, and on the light emitting surfaces of the light emitting diodes 4441 to 44h, the driving conditions are written with letters, symbols, bar graphs, characteristic diagrams shown in FIG. 4, or the like. As a result, the driver can know the driving conditions at the time of driving without paying special attention, so he can concentrate on driving and drive safely. Furthermore, since the oil pump rotation speed characteristics can be easily recognized during operation, operation can be performed in accordance with the driving conditions.

Note that although the data used in the above embodiments is the cumulative value of data generated every moment, this may be an average value.

〔Effect of the invention〕

As explained above, the steering method of the power steering device according to the present invention is such that the oil pump rotation speed is controlled by reading out the oil pump rotation speed characteristic that is most suitable for the driving conditions, so that the steering can always be performed with ease. In addition, since the selected characteristics are displayed, the driver can identify the driving conditions, making driving easier, and if there is an abnormality on the display, the driver can know that there is a malfunction in the power steering system. This has the effect of preventing accidents.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing the configuration of the power steering device, Fig. 2 is a circuit diagram of the control section shown in Fig. 1, Fig. 3 is a graph showing the distribution of vehicle speed and steering amount, Fig. 4 (sudden) -(d) are graphs showing oil pump rotation speed characteristics, FIG. 5 is a graph showing combinations of oil pump rotation speed characteristics, and FIG. 6 is a front view showing the state when the display device is mounted on an actual vehicle. 1. 7-ring part, 2... motor, 2a
...oil pump, 3-fist...control section, 5a...
・Speed sensor, 6@...Φ steering angle detection device, 44・
Fist - Display, 44e to 44h... Light emitting diode 0 Patent applicant Jidosha Kiki Co., Ltd.

Claims (1)

[Claims] In the control method of a power steering device that performs power steering by controlling the rotation speed of an oil pump, multiple types of oil pump rotation speed characteristics that indicate the relationship between the vehicle speed at the time of driving and the oil pump rotation speed are prepared in advance. One type of oil pump rotation speed characteristic is selected according to the driving conditions, and the oil pump is controlled to a rotation speed that matches the vehicle speed at the time of driving according to the selected oil pump rotation speed characteristic. 1. A method for controlling a power steering device, the method comprising: displaying an identification display.