JPH0798489B2 - Power steering control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a control device for a power steering apparatus that appropriately controls a steering force according to a vehicle speed.

[Conventional technology]

2. Description of the Related Art In recent years, power steering devices have been used for steering devices of automobiles and the like to perform light and quick steering operations and reduce driver fatigue. This power steering apparatus generally includes a vehicle speed sensor that sends out a vehicle speed signal according to the vehicle speed and a control circuit that controls the oil flow rate based on the vehicle speed signal sent out by the vehicle speed sensor. The power source drives the oil pump to control the oil flow according to the traveling state, so that the steering can be performed lightly and stably from low speed traveling to high speed traveling. That is, the oil flow rate is increased at a low speed where a large steering force is required, and the oil flow rate is reduced at a high speed when the steering force is small so that the steering can be performed with an appropriate steering force in a wide vehicle speed range.

Generally, such a steering apparatus has a steering angle sensor that outputs a steering angle signal according to a steering angle, and controls an oil flow rate by driving an oil pump only during steering in a vehicle speed range below a reference vehicle speed. However, in the vehicle speed range higher than the reference vehicle speed, the oil pump is always operated to control the oil flow rate according to the traveling state. That is, the oil pump can be basically driven only during steering, and the power supplied to the oil pump during wasted steering is wasted. However, if the oil pump is driven only for steering at all vehicle speeds as described above, there is a problem in that a response delay occurs with respect to sudden steering performed during danger avoidance. Therefore, the oil pump is not driven only during steering in the low speed range where the reference vehicle speed is the upper limit value, which does not require quick response, and the oil pump is constantly operated in the high speed range where the reference vehicle speed is the lower limit value. By operating the oil pump to control the oil flow rate according to the traveling state, the power consumption of the oil pump is reduced.

[Problems to be solved by the invention]

However, according to such a power steering control device, for example, when the speedometer cable for driving the vehicle speed sensor is cut, or when the lead connector connecting the vehicle speed sensor is broken, When the vehicle speed signal input to the control circuit instantly becomes the same as when the vehicle speed is zero and such a failure occurs at high speed running, the oil flow rate increases instantaneously and the steering force is increased accordingly. There was a fear that it would suddenly become lighter and oversteer. On the contrary, in the case of a failure as described above, there is a control device that instantly reduces the oil flow rate and makes the steering force heavy to perform fail-safe.
In such a device, there is a problem that the steering force suddenly becomes heavy and the driver feels uncomfortable.

[Means for solving problems]

The present invention has been made to solve such a problem, and a pulse signal processing circuit that sends out a vehicle speed signal according to a vehicle speed based on a pulsed electric signal generated by a vehicle speed sensor, and this pulse signal processing. A latch circuit for holding and outputting the vehicle speed signal sent by the circuit is provided, and the holding operation of the latch circuit is reset every time N pulse-shaped electric signals generated by the vehicle speed sensor are counted. In the vehicle speed range in which the traveling vehicle speed obtained based on the vehicle speed signal is equal to or higher than the reference vehicle speed, the steering force is controlled according to the vehicle speed, and in the vehicle speed range below the reference vehicle speed, the steering angle signal sent by the steering angle sensor is controlled. The power steering assist is continued for a predetermined time each time is input.

[Action]

Therefore, according to this device, every time N pulse-shaped electric signals generated by the vehicle speed sensor are counted, the value of the vehicle speed signal held and output is updated in the latch circuit, and N pulse-shaped electric signals are output. If not counted, the output signal in the latch circuit is not updated, and the steering force is continuously controlled in accordance with the vehicle speed signal sent by the latch circuit. Then, when the number of the pulsed electric signals is not counted when the traveling vehicle speed obtained based on the vehicle speed signal is in the vehicle speed range equal to or lower than the reference vehicle speed, the actual vehicle speed then becomes the vehicle speed range equal to or higher than the reference vehicle speed. Also, every time the steering angle signal is transmitted, the power steering assist is continuously performed for a predetermined time.

〔Example〕

Hereinafter, the control device of the power steering apparatus according to the present invention will be described in detail. FIG. 1 is a block diagram showing an embodiment of this control device. In the figure, 1 is a steering angle sensor that sends a steering angle signal according to the steering angle, 2 is a vehicle speed sensor that sends out a pulsed electric signal according to the vehicle speed, and 3 is a drive that drives an oil pump (not shown). It is a motor. The steering angle signal sent by the steering angle sensor 1 is a pulse-shaped electric signal according to the steering angle, and one pulse is sent for each predetermined steering angle. The number of pulses of the steering angle signal sent by the steering angle sensor 1 is counted while being reset by the counter 4 every 60 seconds, and the count value counted by the counter 4 every 60 seconds is an average. It is adapted to be input to the steering amount memory 5 synchronously every 60 seconds. Then, the average steering amount memory 5 sends an average steering signal corresponding to the input count value to the decoder 6. The steering angle signal sent from the steering angle sensor 1 is also input to the one-shot timer 7, and the one-shot timer 7 receives the pulse of the steering angle signal sent from the steering angle sensor 1. And gate 8 for "H" level signal continuously for each predetermined time
It is designed to be sent to one end of the.

On the other hand, a pulsed electric signal corresponding to the vehicle speed sent by the vehicle speed sensor 2 is input to the counters 9 and 10 and the N pulse counter 11, and the number of pulses of the signal input to the counter 9 is The counter counts while resetting every 60 seconds. Also,
The pulse number of the signal input to the counter 10 is adapted to be counted while being reset every 1 second in the counter. Further, the N pulse counter 11 sets the "H" level signal as a reset signal in the latch circuit every time the number of pulses of the input pulsed electric signal is counted.
It is designed to send to 12 and 13. The counter
A pulse signal processing circuit is composed of 10 and the vehicle speed memory 15.

The count value counted by the counter 9 every 60 seconds is input to the average vehicle speed memory 14 in synchronization with every 60 seconds. The average vehicle speed memory 14 outputs an average vehicle speed signal corresponding to the input count value. The data is sent to the decoder 6 via the latch circuit 12. That is, the latch circuit 12 holds and outputs the average vehicle speed signal transmitted from the average vehicle speed memory 14 while being reset every N pulses by the reset signal transmitted from the N pulse counter 11.

Further, the count value counted by the counter 10 every 1 second is adapted to be input to the vehicle speed memory 15 in synchronization with every 1 second, and the vehicle speed memory 15 outputs a vehicle speed signal corresponding to the input count value to the latch circuit. The signal is sent to the comparator 16 and the gate circuits 17 to 20 via 13. The latch circuit 13 is also the N pulse counter 11 in the same manner as the circuit 12.
The reset speed signal sent from the vehicle speed memory 15 is held and output while the reset speed signal sent from the vehicle speed memory 15 is reset while resetting every N pulses. The comparator 16 outputs the vehicle speed signal input via the latch circuit 13 to the reference vehicle speed. "H" when the value is below the signal value
A level signal is sent to the other end of the AND gate 8. That is, when the traveling vehicle speed obtained based on the vehicle speed signal sent by the latch circuit 13 is in the vehicle speed range equal to or lower than the reference vehicle speed, the comparator 16 sends out an "H" level signal.

The decoder 6 determines what traveling condition is currently present from the average steering signal sent from the average steering amount memory 5 and the average vehicle speed signal sent from the average vehicle speed memory 14, and is connected to the gate circuits 17 to 20. The output signal is sent to any one of the four output lines.
20 receives this output signal and opens the gate. Reference numerals 21 to 24 are pattern memories corresponding to the gate circuits 17 to 20, and the horizontal axis represents the vehicle speed and the vertical axis represents the number of control circuits of the drive motor 3. That is, the pattern memory 21
24 have different vehicle speed / revolution characteristics, and the revolution speed of the drive motor 3 is controlled based on the pattern memories 21-24. That is, the gate circuits 17 to 20 are adapted to receive the vehicle speed signal sent from the vehicle speed memory 15 via the latch circuit 13, and the traveling vehicle speed obtained based on this vehicle speed signal and the opened gate. The control rotation speed of the drive motor 3 is determined from the pattern memory corresponding to the circuit, and the drive motor drive signal according to the control rotation speed is sent out via the OR gate 25. The pattern memories 21 to 24 are pattern memories in which the output is zero in the vehicle speed range where the traveling vehicle speed is equal to or lower than the reference vehicle speed compared by the comparator 16. Further, the drive motor drive signal sent from the OR gate 25 is transmitted via the OR gate 26 to the drive motor 3
The gate circuit 27 is opened at the other end of the OR gate 26 so that the drive motor drive signal for rotating the drive motor 3 at the maximum rating is input. . The gate circuit 27 is designed to open when the output signal of the OR gate 28 reaches the “H” level. The output of the AND gate 8 is provided at one end of the OR gate 28 and the load sensor 29 is provided at the other end of the OR gate 28. The "H" level signal sent by is input. The load sensor 29 detects the reaction force of the handle,
When this reaction force exceeds a predetermined level, an "H" level signal is sent out.

Next, the operation of the control device for the power steering apparatus configured as described above will be described. That is, when the automobile starts traveling, the vehicle speed sensor 2 sends out a pulsed electric signal corresponding to the vehicle speed. This pulsed electric signal is input to the counters 9 and 10 and the N pulse counter 11, and the number of pulses is counted by the counters 9 and 10 every 60 seconds and every 1 second. The count value counted by the counter 9 is input to the average vehicle speed memory 14 and
Sends an average vehicle speed signal corresponding to the input count value to the decoder 6 via the latch circuit 12. Also the counter
The count value counted in 10 is the vehicle speed memory 15
The vehicle speed memory 15 sends the vehicle speed signal corresponding to the input count value to the comparator 16 and the gate circuits 17 to 20 via the latch circuit 13. At this time, the average vehicle speed signal and the vehicle speed signal held and output by the latch circuits 12 and 13 are N
The reset signal is sent from the pulse counter 11 every N pulses and is sent while being updated every N pulses.

On the other hand, the comparator 16 compares the input vehicle speed signal with the reference vehicle speed signal value, that is, compares the traveling vehicle speed obtained based on the vehicle speed signal with the reference vehicle speed, and when the traveling vehicle speed is equal to or lower than the reference vehicle speed, "H" The level signal is output to the AND gate 8.
In this embodiment, the reference vehicle speed is set to 10 km / H.
At this time, when the steering angle signal is sent from the steering angle sensor 1, the one-shot timer 7 continues for a predetermined time in response to the first pulse signal of the steering angle signal, and the AND gate outputs the "H" level signal. Send to 8. Since the "H" level signal sent from the comparator 16 is input to the other end of the AND gate 8, the "H" level signal is sent from the AND gate and the gate circuit 27 is opened. As a result, the drive motor 3
Rotates at the maximum rating to maximize oil flow and
Power steering assistance is done with% output. When the one-shot timer 7 has passed a predetermined time and the "H" level signal is no longer sent, the gate circuit 27 closes. However, when a steering angle signal is further sent from the steering angle sensor 1, this steering angle signal is output. In response to the pulse signal of the signal, the one-shot timer 7 again sends the "H" level signal.

On the other hand, the counter 4 counts the number of pulses of the steering angle signal sent by the steering angle sensor 1 every 60 seconds, and the average steering amount memory 5 sends the average steering signal according to the count value counted by the counter 4 to the decoder 6. Send out. Decoder 6
From the average steering signal and the vehicle speed memory 14, the latch circuit 12
Based on the average vehicle speed signal input via the, the current driving condition is determined, and the output signal is sent to any of the four output lines. The gate circuit (any of the gate circuits 17 to 20) to which this output signal is input is opened, but when the traveling vehicle speed compared by the comparator 16 is equal to or lower than the reference vehicle speed, the gate circuits 17 to 20 are responded to. Pattern memory 21
Since ~ 24 has a pattern in which the output becomes zero, the drive motor drive signal is not transmitted from the OR gate 25. That is, when the traveling vehicle speed is in the vehicle speed range equal to or lower than the reference vehicle speed, the drive motor 3 is driven only based on the steering angle signal sent by the steering angle sensor 1. When the reaction force of the steering wheel exceeds a predetermined level, a "H" level signal is sent from the load sensor 29, the drive motor 3 rotates at the maximum rating regardless of the presence or absence of the steering angle signal, and 100% output. Power steering assistance is done with.

Then, when the vehicle speed increases and the traveling vehicle speed compared by the comparator 16 exceeds the reference vehicle speed, the "H" level signal which the comparator 16 has previously sent to the AND gate 8 is no longer sent. That is, in the vehicle speed range in which the traveling vehicle speed is equal to or higher than the reference vehicle speed, the output of the AND gate 8 does not become the “H” level even if the steering angle sensor 1 sends the steering angle signal, and the road sensor 29 outputs the “H” level. The gate circuit 27 does not open unless a signal is transmitted.

On the other hand, the decoder 6 judges the traveling condition at this time and sends the output signal to any of the four output lines, and any one of the gate circuits 17 to 20 is opened. Then, the vehicle speed signal sent from the vehicle speed memory 15 is input to the gate circuits 17 to 20 via the latch circuit 13, the traveling vehicle speed obtained by the vehicle speed signal and the pattern memory corresponding to the opened gate circuit. From this, the control rotation speed of the drive motor 3 is determined, and a drive motor drive signal corresponding to the control rotation speed is transmitted via the OR gate 25. The drive motor drive signal is input to the drive motor 3 via the OR gate 26 because the gate circuit 27 is not opened, and the drive motor 3 rotates at a predetermined control rotation speed. In this way, when the traveling vehicle speed is in the vehicle speed range equal to or higher than the reference vehicle speed, the rotation speed of the drive motor 3 is controlled according to the traveling condition and the traveling vehicle speed, and the oil flow rate is controlled.

Next, the operation when the vehicle speed sensor fails, which is a feature of the present invention, will be described. That is, when the speed meter cable (not shown) for driving the vehicle speed sensor 2 is cut during traveling, or when the lead connector (not shown) connecting the vehicle speed sensor 2 and the device is broken, the vehicle speed sensor 2 detects the vehicle speed. The pulse-shaped electric signal according to the above is no longer generated, or even if the vehicle speed sensor 2 outputs the pulse signal, the pulse signal is not input to the counters 9 and 10 and the N pulse counter 11. When the pulse signals are no longer input to the counters 9 and 10, the count values in the counters 9 and 10 become zero, and the average vehicle speed memory 14 and the vehicle speed memory 15 show that the actual vehicle speed (hereinafter referred to as the actual vehicle speed) is not zero. Nevertheless, it starts to output the average vehicle speed signal and the vehicle speed signal that are equal to those when the vehicle speed is zero. However, N pulse counter
Since the pulse signal is not input to 11 either, the N pulse counter 11 cannot continue counting and does not output the "H" level signal. Therefore, the latch circuit 12
Even if the reset signal is not input to and 13 and the average vehicle speed memory 14 and the vehicle speed memory 15 start to output the average vehicle speed signal and the vehicle speed signal which are equal to those when the vehicle speed is zero, the latch circuits 12 and 13 do not take in these vehicle speed signals. . That is, the latch circuits 12 and 13 hold and continue to output the average vehicle speed signal and the vehicle speed signal immediately before the average vehicle speed memory 14 and the vehicle speed memory 15 start to output the output signal in the same state as when the vehicle speed is zero.

For example, in the high speed range above the reference vehicle speed, if the vehicle speed sensor fails as described above, the latch circuits 12 and 13 hold and output the average vehicle speed signal and the vehicle speed signal corresponding to the traveling vehicle speed immediately before the failure in the high speed range. . When the traveling vehicle speed is in the high speed range, the OR gate 25 sends out the drive motor drive signal according to the traveling condition and the vehicle speed, and when the latch circuits 12 and 13 hold the signal immediately before the failure, the OR gate 25 also accompanies it. The drive motor drive signal immediately before the failure is continuously transmitted. As a result, the drive motor 3 continues to rotate, and the oil flow rate is continuously controlled. That is, even if the vehicle speed sensor fails during high-speed traveling, the steering force does not suddenly decrease or increase, and the driver can continue driving without feeling a sense of discomfort. Further, since the holding operation in the latch circuits 12 and 13 is continued unless the "H" level reset signal is input from the N pulse counter 11, the drive motor 3 operates in the preceding vehicle speed range immediately before the vehicle speed is broken down. The rotation speed is controlled in accordance with the above, and the control value of the oil flow rate becomes substantially constant with respect to the front vehicle speed range.

On the other hand, when a failure occurs in the vehicle speed sensor in the low speed range below the reference vehicle speed, the latch circuits 12 and 13 hold and output the average vehicle speed signal and the vehicle speed signal corresponding to the traveling vehicle speed immediately before the failure in the low speed range. When the traveling vehicle speed is in the low speed range, the comparator 16 sends the "H" level signal to the AND gate 8. Therefore, the comparator 16 continuously sends the "H" level signal. Be done. As a result, the drive motor 3
Even if the vehicle speed sensor fails, the rotational drive is continuously performed based on the steering angle signal sent from the steering angle sensor 1. Further, since the holding operation in the latch circuits 12 and 13 is continuously performed unless the "H" level reset signal is inputted from the N pulse counter 11, the comparator 16
Continues to send an "H" level signal to the AND gate 8 for all vehicle speed ranges. Therefore, the drive motor 3 is controlled based on the steering angle signal sent by the steering angle sensor 1 in the entire vehicle speed range. That is, even if the actual vehicle speed thereafter becomes the high speed range, the comparator 16 continues to send the "H" level signal to the AND gate 8. Therefore, when the steering angle signal is sent from the steering angle sensor 1 when the actual vehicle speed is in the high speed range, the one-shot timer 7 continues for a predetermined time in response to the first pulse signal of the steering angle signal. The "H" level signal is sent to the AND gate 8, and the "H" level signal is sent from the AND gate 8 and the gate circuit 27
Opens, and the drive motor 3 rotates at the maximum rated rotation.
This maximizes the oil flow rate and provides power steering assistance at 100% output. The steering angle sensor 1 intermittently generates a steering pulse due to minute steering that is present during straight running, but if the timer time of the one-shot timer 7 is appropriately set with respect to the generation interval of the steering pulse, the drive is performed. The motor 3 can be continuously driven to rotate,
Power steering assistance can be continuously performed at 0% output. That is, even if the vehicle speed sensor malfunctions in the low speed range and then enters the high speed range, the steering force is still controlled based on the steering signal. In this case, there is no response delay as when driving the oil pump each time, and the power steering assist does not respond even when sudden steering is performed during high speed running. You can do it without.

When the vehicle speed sensor fails in the low speed range, the power steering assist is performed at 100% output as described above for all vehicle speeds, that is, the power steering assist is performed at 100% output even in the high speed running state. However, a sudden change in the steering force makes the driver feel uncomfortable, and even if the steering force does not change rapidly, the power steering assist of 100% output does not cause any trouble.

In the present embodiment, the N pulse counter 11 sends the signal of "H" level every time N pulses are counted at all vehicle speeds. However, it is not always necessary to use only one kind of count value for all vehicle speeds. Of course, a plurality of types of pulse counters having different count values depending on the vehicle speed may be used.
By doing so, speed correction of the reset cycle for resetting the latch circuits 12 and 13 can be performed.

Further, in the present embodiment, when the gate circuit 27 is opened, the drive motor drive signal for rotating the drive motor 3 at the maximum rating is sent to the OR gate 26, but such a drive motor drive signal is not necessarily required. Often,
For example, it may be a drive signal that causes the drive motor 3 to gradually stop over time. By doing so, it is possible to omit the one-shot timer 7.

Further, although the counter 10 and the vehicle speed memory 15 constitute the pulse signal processing circuit, it is not necessary to use such a digital processing circuit and, for example, depending on the frequency of the pulsed electric signal sent from the vehicle speed sensor 2. F that generates
The generated voltage may be used as the vehicle speed signal by using a −V converter.

In this embodiment, the oil flow rate is controlled in order to control the output of the power steering apparatus, that is, the steering force. However, the oil pressure may be controlled to control the steering force. Good.

〔The invention's effect〕

As described above, according to the control device for a power steering apparatus of the present invention, the value of the vehicle speed signal held and output in the latch circuit is updated every time N pulse-shaped electric signals generated by the vehicle speed sensor are counted. When N pulse-shaped electric signals are not counted, the output signal in the latch circuit is not updated, and the steering force is continuously controlled according to the vehicle speed signal sent by the latch circuit. Therefore, even if the vehicle speed sensor fails during high-speed traveling, the vehicle speed signal immediately before the failure is held in the latch circuit,
The sudden change in the steering force does not occur, and the driver can continue driving without feeling discomfort. Further, when the traveling electric vehicle speed obtained based on the vehicle speed signal is in the vehicle speed range equal to or lower than the reference vehicle speed, when N pulse-shaped electric signals are not counted,
After that, even if the actual vehicle speed is in the vehicle speed range equal to or higher than the reference vehicle speed, the power steering assist is continuously performed for a predetermined time each time the steering angle signal is transmitted, so if the predetermined time is appropriately determined, It is possible to continue the operation without trouble even in the power steering apparatus that reduces the power consumption without causing a problem that a response delay occurs with respect to the sudden steering performed when avoiding the danger.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a power steering apparatus according to the present invention. 1 ... Steering angle sensor, 2 ... Vehicle speed sensor, 3 ... Drive motor, 7 ... One-shot timer, 10 ... Counter, 11 ... N pulse counter, 13 ... Latch circuit, 15 ...
… Vehicle speed memory, 16 …… comparator.

Claims (1)

[Claims] 1. A vehicle speed sensor for generating a pulsed electric signal according to a vehicle speed, a pulse signal processing circuit for transmitting a vehicle speed signal according to a vehicle speed based on the pulsed electric signal generated by the vehicle speed sensor, and this pulse. A latch circuit for holding and outputting a vehicle speed signal sent from the signal processing circuit; and an N pulse counter for resetting the holding operation of the latch circuit each time N pulse-shaped electric signals generated by the vehicle speed sensor are counted, A control device for a power steering apparatus that controls a steering force according to a vehicle speed signal sent from a latch circuit, comprising a steering angle sensor for sending a steering angle signal according to a steering angle, and a vehicle speed sent by the latch circuit. When the traveling vehicle speed obtained based on the signal is equal to or higher than the reference vehicle speed, the steering force is controlled according to the traveling vehicle speed, and when the traveling vehicle speed is equal to or lower than the reference vehicle speed, the steering angle sensor is sent out. Control device for a power steering apparatus, characterized in that the predetermined time every time the steering angle signal is input continuously for and control means for performing power steering assist.