JPH0225838B2 - - Google Patents

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 an automobile tends to increase as the vehicle speed decreases. Therefore, if this steering resistance is canceled using a power steering device that operates an oil pump to circulate the oil, the vehicle speed will decrease. Even if the steering force is small, the required steering can be performed with a small steering force. For this reason, conventional power steering devices have been used that increase the rotational speed of the oil pump when the vehicle speed is low, and decrease the rotational speed of the oil pump as the vehicle speed increases, allowing for light steering. There is. When power steering becomes unnecessary, the rotation of the oil pump is stopped 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, but with power steering systems using conventional control methods, the oil pump stops when the vehicle speed exceeds a predetermined speed. Therefore, it has the disadvantage of requiring a large steering force under such driving conditions. [Objective 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 rotation speed according to driving conditions. In order to achieve this purpose, this invention
Several types of oil pump rotation speed characteristics that indicate the relationship between the oil pump rotation speed and the vehicle speed are prepared, and the optimum oil pump rotation speed characteristic is selected according to the driving conditions. Hereinafter, the present invention will be explained in detail using drawings showing embodiments. [Embodiment] FIG. 1 is a diagram showing the configuration of a power steering device.
In the figure, 1 is a steering section, 2 is a motor that drives the oil pump 2a, 3 is a control section, 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, 7 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 adapted to send out a pulse proportional to the amount of steering. Starter sensor 5
When a starter motor (not shown) for starting the engine is operating, the voltage of the battery 8 is sent to the engine sensor 5c, and the voltage of the battery 8 is sent to the engine sensor 5c when the engine is operating. Furthermore, motor 2
The diode 2b connected in parallel with the motor 2 is a transient voltage absorbing diode. The control unit 3 includes waveform shaping circuits 30 and 31, oscillation circuits 32 and 33, a frequency division ratio setting circuit 34, an alarm display 35, a switching circuit 36, a current value determination circuit 37, and a control circuit 3.
8, 39, stabilizing circuits 40, 41, 42, a pull-up circuit 43, and a display 44 for displaying steering characteristics. The waveform shaping circuit 30 is composed of resistors 30a to 30d and NAND circuits 30e and 30f, and the waveform shaping circuit 31 is composed of resistors 31a and 31b and a diode 31.
c, NAND circuits 31d and 31e. The oscillation circuit 32 is composed of resistors 32a, 32b, capacitors 32c, 32d, and a ceramic oscillator 32e, and the oscillation circuit 33 is composed of a resistor 33a, capacitors 33c, 33d, and a ceramic oscillator 33e. The frequency division ratio setting circuit 34 is a resistor 3
4a to 34c, and switches 34e to 34g, and since the number of pulses generated from the speed sensor 5a per unit traveling distance may differ depending on the type of car, it is controlled by appropriately setting the switches 34e to 34g. The frequency dividing ratio of the frequency dividing circuit built in the circuit 39 is controlled, and the terminal 3
The number of pulses sent out from 9a per unit traveling distance is made to remain the same depending on the vehicle type. The alarm indicator 35 includes a resistor 35a and a light emitting diode 35b.
It is composed of. Switching circuit 36
are resistors 36a to 36f, transistors 36g, 3
It consists of 6h. The current value setting circuit 37 is composed of resistors 37a to 37m, a capacitor 37p, an amplifier 37q, and comparators 37r to 37t, so that the current flowing through the motor 2 can be adjusted to a predetermined value of 3.
It is designed to determine which of the type setting values is exceeded. The control circuit 38 has terminals 38a~
Based on the signal supplied to the terminal 38k, the processing described below is performed and a 5-bit parallel signal corresponding to the input signal is output from the terminals 38l to 38q, and an alarm signal is output from the terminals 38r and 38s at necessary times.
Sends a reset signal and also connects terminals 38t to 38w.
A zero level signal for displaying steering characteristics is sent to one of the terminals. As described above, the control circuit 39 divides the signal supplied to the terminal 39e at a division ratio according to the signals supplied to the terminals 39b to 39d, and outputs the divided signal to the terminal 39a, and the signal is supplied to the terminal 39f. When a signal is supplied to the terminal 39g, a zero level signal is sent to the terminals 39h to 39l, and a signal whose duty ratio changes according to the signal supplied to the terminals 39m to 39s is sent to the terminals. It is designed to be sent from 39t to 39w. Stabilization circuit 40~
42 is designed to stabilize the supplied voltage to 5 volts and output it, and the stabilizing circuit 41 is composed of resistors 41a and 41b, a capacitor 41c, and a Zener diode 41d, and the stabilizing circuit 42 is composed of resistors 42a and 42b. , a capacitor 42c, and a Zener diode 42d. The pull-up circuit 43 is composed of resistors 43a to 43d. The display 44 is composed of resistors 44a to 44d and light emitting diodes 44e to 44h, and is adapted to display the steering characteristic automatically selected by the switch 4 or the control circuit 38. Note that the control circuit 38 is designed to preferentially display the steering characteristics determined by the switch 4. As described above, in the present invention, the optimum oil pump rotation speed characteristic is selected according to the driving conditions, and the lateral acceleration obtained by multiplying the vehicle speed and the steering amount is used as the driving condition. FIGS. 3a and 3b 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. It is assumed that the vehicle speed pulse is proportional to the speed per hour, and the steering pulse is 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 interval is too long, it will no longer correspond to the actual situation.
If it is too short, the rotation speed characteristics will change frequently and give a strange feeling, so a period of about 30 seconds is appropriate. The lateral acceleration is obtained 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, the vehicle speed is the cumulative value of vehicle speed pulses for 30 seconds,
The steering amount is calculated as the cumulative value of the steering pulses for 30 seconds.
The vehicle speed, steering amount, and lateral acceleration during the period shown in range A in the figure are determined as follows. Vehicle speed = 40 x 2 + 10 x 3 + 50 x 2 + 30 x 3 = 80 + 30 + 100 + 90 = 300 Steering amount = 200 x 2 + 0 x 2 + 150 x 2 + 0 x 2 + 100 x 2 = 400 + 0 + 300 + 0 + 200 = 900 Lateral acceleration = 300 x 900 = 270000 Similarly, the range shown in Figure 3 Vehicle speed during the period shown in B,
The steering amount and lateral acceleration are calculated as follows. Vehicle speed = 30 x 6 + 20 x 2 + 40 x 2 = 300 Steering amount = 100 x 6 + 50 x 2 + 200 x 1 = 900 Lateral acceleration = 300 x 900 = 270000 As can be seen from Figure 3, the driving conditions are different during periods A and B. However, since the cumulative value of the data generated over 30 seconds was used for the vehicle speed and steering amount, the lateral acceleration would be the same value, making it impossible to distinguish between them even though the driving conditions were different. This is because, as is clear from the fact that lateral acceleration does not occur when steering is not performed, differences in lateral acceleration due to differences in vehicle speed and distribution of steering occurrence are not taken into consideration. This is calculated by multiplying the short-time vehicle speed and the short-time steering amount obtained every 3 seconds, which is a period sufficiently shorter than 30 seconds, to obtain the short-time lateral acceleration, and then cumulating this short-time lateral acceleration for 30 seconds. If lateral acceleration is used, the difference in the distribution of vehicle speed and steering occurrence will be reflected, making it possible to identify the driving state. Table 1 shows the vehicle speed, steering amount, and short-term lateral acceleration every 3 seconds to determine the long-term lateral acceleration for periods A and B in FIG.

【table】

〔Effect of the invention〕

As explained above, the power steering device control method according to the present invention controls the rotation speed of the oil pump according to the oil pump rotation speed characteristics most suitable for the driving conditions. It has the effect of allowing easy steering even when driving conditions are low, and the short-term lateral acceleration is obtained by multiplying the short-term vehicle speed and the amount of steering, and the long-term lateral acceleration is obtained by summing up the short-term lateral acceleration. This has the effect that differences in driving conditions are appropriately reflected in driving conditions.

[Brief explanation of drawings]

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 a-
d is a graph showing the oil pump rotation speed characteristics, the fifth
The figure is a graph showing combinations of oil pump rotation speed characteristics. 1...Steering section, 2...Motor, 2a...
...Oil pump, 3...Control unit, 5a...Speed sensor, 6...Steering angle detection device.

Claims (1)

[Claims] 1. In a control method for a power steering device that performs power steering by controlling the rotational speed of an oil pump, the short-term vehicle speed obtained in each relatively short first period is multiplied by the short-term steering amount. Calculate the lateral acceleration and calculate the long-term lateral acceleration obtained from all the short-term lateral accelerations obtained within the second period, which is made up of a plurality of consecutive first periods, and the long-term lateral acceleration within the second period. The required long-term vehicle speed is determined from all the determined short-term vehicle speeds, and from this determined value, the 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. A control method for a power steering device that selects one type of oil pump rotation speed characteristic from among them and controls the oil pump to a rotation speed that matches the vehicle speed at the time of traveling according to the selected oil pump rotation speed characteristic.