JPS592968A - Power steering gear - Google Patents

Abstract

PURPOSE:To prevent a steering force from rapidly varying at the time of starting or stopping a motor which is controlled by an output from a sensor detecting a running condition, by controlling the motor so that the rotating speed thereof is gradually increased or decreased when starting or stopping it. CONSTITUTION:When steering while the vehicle is stopped, a signal from a steering angle sensor 101 is converted into a DC voltage by a frequency-to-voltage converter 120, and the voltage is supplied to a comparing circuit 150 and a signal generator 210. When steering by a quantity of not less than that set by the comparing circuit 150, the circuit 150 generates a motor-driving signal to turn ON a switching circuit 200, whereby a voltage signal is supplied to the signal generator 210. The signal genrator 210 integrates both of the voltages, and sends the integrated result to a voltage regulator 230, which controls the voltage on the motor 31 so as to gradually increase the rotating speed of the motor 31. The regulator 230 similarly controls the voltage also when the vehicle is running, and when the motor 31 is stopped, the regulator 230 controls the voltage on the motor 31 so as to gradually decrease the rotating speed of the motor 31.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering device that is mounted on each electric vehicle and used to reduce the steering force of the driver.

In recent years, power steering devices have been widely used for light steering. In this system, an oil pump is driven by a motor, and oil sent from the oil pump is supplied to a power steering section, thereby enabling steering with a small amount of force.

Also, recently, efforts have been made to control motors according to operating conditions to reduce the energy used for power steering.

However, in such conventional devices, if the pump starts or stops during steering, the steering force changes suddenly, making it impossible to perform smooth steering.Also, a large starting current flows when the motor starts, so the circuit through which the starting current flows Since the parts used for this purpose must have a capacity that is not large enough to withstand this current, this has the disadvantage of being uneconomical.

Therefore, an object of the present invention is to provide an economical power steering device in which the steering force does not suddenly change when an oil pump is started or stopped.

In order to achieve this object, the invention is such that the current flowing through the motor is gradually changed when the motor is started and stopped. Hereinafter, the present invention will be described in detail using drawings showing embodiments.

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram thereof. In the figure, reference numeral 1 indicates sensors for detecting running conditions, including a vehicle speed sensor 100 that generates a vehicle speed signal with a number of pulses proportional to the running speed, a steering angle sensor 101 that generates a steering signal with a number of pulses that corresponds to the steering angle, and a pulse A frequency O voltage converter that generates a DC voltage proportional to the number of
(hereinafter referred to as F-■ converter) 110, 120,
It is composed of comparator circuits 130, 140, and 150. 2 is a control circuit, and a switch circuit 2
00, a signal generator 210, a voltage regulator 230, a vehicle speed sensitive circuit 250, and an overcurrent protection circuit 260. Further, 3 is a motor circuit.

FIG. 2 specifically shows these circuits. The steering angle sensor 101 is composed of a light emitting diode 102, resistors 103 and 104, and a phototransistor 105. Then, a slit plate (not shown) with slits carved therein rotates according to the steering angle, and as this slit plate passes through the light emitting surface of the light emitting diode 102, the light emitted from the light emitting diode 102 is intermittent by the number of slits it passes through. , this interruption is the phototransistor 105
has been detected in F-V converter 110 is resistor 111
, 112, transistor 113, capacitor 114
, 115, diodes 116, 111,
A DC voltage proportional to the number of pulses of the signal supplied from the vehicle speed sensor 100 is generated. In addition, the F-V converter 12
0 consists of resistors 121 and 122, a transistor 123, capacitors 124 and 125, and diodes 126 and 127, and operates in the same way as the F-V converter 110. The comparator circuit 130 includes resistors 131, 132,
133 and a comparator 134, when the vehicle speed is the first
A constant is set so that the signal supplied from the F-V converter 110 causes an output signal to be sent from the comparator 134 when the speed is greater than or equal to . Here, the output signal at this time is defined as a motor drive signal, and the vehicle speed region below the first speed is defined as an extremely low speed region. Comparator circuit 1
40 is composed of resistors 141, 142, 143, and a comparator 144, and receives an output signal from the comparator 144 in response to a signal supplied from the F-V converter 110 when the vehicle speed is equal to or higher than a second speed that is larger than the first speed. A constant is set to send. Here, the output signal at this time is defined as a motor disconnection signal, the vehicle speed range that is higher than the first speed and lower than the second speed is defined as a low speed range, and the vehicle speed range that is higher than the second speed is defined as a high speed range. defined as the area. Comparator circuit 150 includes resistors 151, 152, 153
, a comparator 154, and a constant is set so that the comparator 154 outputs an output signal when the steering is performed by a predetermined amount or more, and the output signal at this time is defined as a motor drive signal. The switch circuit 200 includes transistors 201 , 202 , 203 , 204 and resistors 205 , 206 , 207 . The signal generator 210 includes resistors 211, 212, 213, 2
14, 215, a capacitor 216, 2)7, and an operational amplifier (hereinafter referred to as OP amplifier) 219.When a signal with steep rising/falling waveforms is supplied, the rising and falling waves are slow. generates an output signal. Yet the magnitude of its output signal is proportional to the magnitude of the signal provided to the op amp 2190 inverting input terminal.

Voltage regulator 230 includes resistors 231 , 232 , 233
, 234.

235, 236, 237, Conde/Su238, OP
'77 pump 239, comparator 240, transistor 2
It is composed of 41.242. The OP amplifier 239 generates a triangular wave, and the comparator 240 changes the duty ratio of the output signal by slicing the signal supplied to the inverting input terminal with the signal supplied to the non-inverting input terminal. By controlling these signal transistors 241 and 242, a voltage proportional to the duty ratio of the supplied signal is supplied to the motor circuit 3. Heavy speed sensitive circuit 25
0 is OP amplifier 251, transistor 253, resistor 25
4, 255, and as the vehicle speed increases, the current flowing through the transistor 253 increases. The overcurrent protection circuit 260 includes resistors 261 and 262.
, 263, 264, a transistor 265, a comparator 266, a relay 26T1, and a relay contact 268, which protects the transistor 242 when an overcurrent flows through the motor circuit 3. The motor circuit 3 includes a motor 31, a resistor 32, and a diode 33.

The operation of the device according to the present invention configured as described above is as follows. First, when the vehicle is stopped and the vehicle is not being steered, the steering angle sensor 101 does not generate a signal, and the F-V converter 120 also does not generate an output voltage. Therefore, since the converter circuit 150 does not generate a motor drive signal, the transistor 201 is turned off. Also, since the car is not running, the vehicle speed sensor 10
0 does not generate a signal, and therefore the F-V converter 110 does not generate an output, the output of the comparator circuit 130 is at the rlJ level, and the output of the comparator circuit 140 [o
” level and forest, and this K means transistor 20.
2 is off, and transistor 203 is on. As a result, the pace voltage of transistor 204 is
The only current supplied through the transistor 20 is
4 is on.

When transistor 204 is on, resistors 211 and 21
The voltage at the connection point 2 becomes approximately "0" level, and the signal generator 21.0 outputs the "1" level output signal to the voltage regulator 230.
is supplied to the non-inverting input terminal of the comparator 240. O
The signal shown in FIG. 3A is supplied to the inverting input terminal of the P amplifier 240, but since the signal supplied to the non-inverting input terminal is at the "1" level, the output signal is at the "1" level. ′! ! It has become a ma. Therefore, transistor 2
41 and 242 are off, so the motor 31 does not operate. Although a vehicle speed sensitive circuit 250 is connected to the signal generator 210, since the vehicle speed sensor 100 is not generating a signal since the vehicle is stopped, the F-V converter 11
0 is also not generating a signal. Therefore, transistor 2
53 is off and does not affect the operation of the signal generator 210.

Next, when steering is performed while stopped, the steering angle sensor 101 also generates a signal, which is converted into a DC voltage by the F-V converter 120 and supplied to the converter circuit 150 and the signal generator 210. be done. At this time, the comparator circuit 15
When the magnitude of the signal applied to 0 is less than the value determined by resistors 151 and 152, converter circuit 150 produces no output signal and transistor 201 is off. When stopped, transistor 20
2 is also off, so the transistor 204 is turned on by the base current supplied via the resistor 211 of the signal generator 210, as described above. Therefore, the signal sent from the F-■ converter 120 is short-circuited to ground by the transistor 204 and the signal sent out from the signal generator 210
is not supplied. However, when the steering is performed by a predetermined amount or more determined by the comparator circuit 150, the comparator circuit 150 generates a motor drive signal and outputs a signal to the transistor 2.
01 is turned on. As described above, the transistor 203 is on when the vehicle is stopped, so when the transistor 201 is turned on, the current flowing through the resistor 207 increases and the transistor 204 is turned off. As a result, the resistor 21 is connected to the inverting input terminal of the OP amplifier 219 of the signal generator 210.
1, 212 and the voltage generated by the signal supplied from the F-vig device 120 are added and supplied.

The signal generator 210 performs an integral operation based on the supplied voltage, and the output voltage slowly decreases as shown in FIG. 3BK. Note that, as described above, since the vehicle speed sensitive circuit 250 influences the operation of the signal generator 210 when the vehicle is stopped, this operation does not need to be taken into account. The comparator 240 of the voltage regulator 230 has an inverting input terminal as shown in FIG.
Since the signal shown in is supplied, the comparator 240
generates an output only during the period in which the signal level supplied to the inverting input terminal is higher than the voltage supplied to the non-inverting input terminal. Therefore, the comparator 240 supplies to the transistor 241K a signal whose pulse width decreases with time as shown in FIG. 3CK. As a result, the transistors 241 and 242K are controlled by the signals shown in FIG. 3C, and the inverted voltage is supplied to the motor 31, so that the rotation speed of the motor 31 gradually increases. And motor 3
1 drives a pump of a power steering section (not shown), so the amount of oil fed gradually increases and the steering force required for operating the steering wheel gradually decreases. In this way, since the steering force due to power steering changes gradually, stable steering can be performed.

Since the signal sent from the F-V converter 120 is larger as the steering is performed more rapidly, the signal sent from the signal generator 210 is larger when the steering is performed rapidly, as shown by the dotted line in FIG. When , K changes as shown by the dashed line in FIG. 3B. Since the increase in the current supplied to the motor 311C corresponds to the change in the output signal of the signal generator 210, the motor rotation speed changes as shown in FIG. In FIG. 4, the dotted line represents the change in the rotational speed of the motor 31 when sudden steering is performed, the one-dot chain line represents the change in the motor rotational speed when gentle steering is performed, and the two-dot chain line represents the change when the signal generator 210 is not provided, i.e. It shows the change in motor rotation speed of a conventional device.

Moreover, the steering force also changes depending on the steering speed.

Therefore, when the vehicle is stopped and in a non-steering state (including a state in which the amount of steering is less than a predetermined amount), the motor 31 does not operate, so power steering is not performed. However, when the steering amount is greater than the predetermined amount, the motor 31 The rotation speed increases gradually, and the degree of increase in rotation speed is proportional to the steering speed, so the steering followability is good.
It also provides a smooth steering feel. Furthermore, the power loss of the transistor 242 at the time of starting the starting current of one motor 3 is small, and a transistor with a small rating can be used.

Next, a description will be given of the conditions when the vehicle is traveling at extremely low speeds.

When driving at extremely low speeds without steering, use steering sensor 1.
Since 01 is not generating a signal, the F-V converter 120
Since the comparator circuits 130 and 140 also do not generate output signals due to the extremely low speed range, the transistor 202 is off and the transistor 203 is on.

In this case, as described above, the transistor 204 is turned on, and the signal generator 210 sends out a "1" level signal.
Therefore, the comparator 2404 r of the voltage regulator 230
Since the signal of lJ level is being sent, transistor 2
41 and 242 remain in the off state, and the motor 31
is not working. When driving on rough terrain, the helmsman's hands may vibrate due to vibrations in the vehicle body caused by the unevenness of the road surface, causing him to make slight adjustments to the steering wheel against his will. Since the amount of steering is small, the comparator circuit 150 does not generate a motor drive signal. Therefore, as in the non-steering state, the motor 31 does not operate and power steering does not occur. However, when the vehicle is steered by more than a predetermined amount to change the driving course, the comparator circuit 150 generates a motor drive signal, and the transistor 201 is turned on. On the other hand, since the vehicle speed sensor 10G is running, it generates a signal, and this signal is transmitted to the F-V converter 1.
10, it is converted to DC voltage and sent to the comparator circuit 130.
, 140, but since the speed is extremely low, these comparator circuits do not generate output signals. Therefore, the transistor 202 is off and the transistor 203 is on. As a result, the transistors 201, 20
The current flowing through resistor 207 generates a voltage that turns transistor 204 off.

When transistor 204 is turned off, signal generator 210
Resistors 211 and 2 are connected to the inverting input terminal of the op amp 219.
The voltage determined by 12 and the voltage according to the signal supplied from the F-V converter 120 are added and supplied. For this reason,
The signal generator 210 and the voltage regulator 230 perform the same operations as when the vehicle is in the stopped state and steering is being performed. As a result, the rotational speed of the motor 31 gradually increases, and the degree of this increase changes depending on the steering speed.

Therefore, even when driving in an extremely low speed range, the motor 31 does not operate in a non-steering state or in a small steering amount range that can be considered as a non-steering state, and power steering is not performed at this time. When the steering is performed by a predetermined amount or more, the motor rotation speed gradually increases, and the degree of rotation crane increase is proportional to the steering speed, so the steering followability is good.
In addition, a smooth steering feeling can be obtained.At this time, since the motor 31 starts operating after the steering starts, a response delay occurs in the power steering, but since the running speed is extremely low since it is in an extremely low speed range, the response delay causes the operation to be delayed. It does not lead to any of the above dangers.

Next, to explain the operation in the low speed range, when the vehicle speed increases without steering and this vehicle speed reaches the first speed, the voltage at the inverting input terminal of the comparator 134 of the comparator circuit 130 changes to the voltage at the non-inverting input terminal. Since the voltage becomes higher than the voltage, the comparator 134 generates a motor drive signal, and the transistor 202 is turned on. Since the transistor 203 is turned on when the vehicle speed is outside the high speed range, the voltage generated in the resistor 207 due to the current flowing through the transistors 202 and 203 causes the transistor to turn off! 204 is turned off.

When transistor 204 is turned off, signal generator 210
The inverting input terminal of the op amp 219 has a resistor 211,
A voltage determined by 212 is supplied. As a result, a signal as shown in FIG. 3B is sent from the output terminal of the OP amplifier 219, and as this signal changes, the motor 31 receives an inverted version of the signal shown in FIG. Since the voltage is supplied for a longer duration, the rotational speed of the motor 31 gradually increases. At this time, when steering is performed, a signal generated from the steering angle sensor 101 is sent to the F-V converter 120.
The signal generator 2 converts it into a DC voltage proportional to the steering amount.
10. In this case, the voltage supplied to the inverting input terminal of the OP amplifier 2190 is the sum of the voltage determined by the resistors 211 and 212 and the voltage generated by the signal supplied from the F-V converter 120.
The output signal 9 changes as shown by the dotted line in FIG. 3B when a sudden steering is performed, and changes as shown by a dashed line when a slow steering is performed. As a result, the rotation speed of the motor 31 increases as shown by the dotted line in FIG. 4 when a sudden steering is performed, and as shown in a dashed-dotted line when a gentle steering is performed, and reaches a predetermined rotation speed. . Note that when the vehicle speed reaches the first speed, the motor 31 starts operating, and if steering is not being performed at this time, the motor 31 reaches the predetermined rotation speed in about 1 second.

When the vehicle speed is further increased after the motor rotation speed reaches a predetermined value, the output voltage of the F-V converter 110 also increases in proportion to the vehicle speed. Since this signal is supplied to the non-inverting input terminal of the OP amplifier 251 of the vehicle speed sensing circuit 250, the output voltage of the OP amplifier 251 increases as the vehicle speed increases. The output of this OP amplifier 251 is the transistor 253
Since the collector current of transistor 253 increases in proportion to the increase in vehicle speed. As a result, the current flowing through the resistor 213 of the signal generator 210 also increases in proportion to the increase in vehicle speed, so the voltage at the inverting input terminal of the OP amplifier 219 decreases, and the output from the OP amplifier 219 increases as the vehicle speed increases. A signal of increasing voltage is provided to comparator 240 . As mentioned above, the comparator 240 outputs a pulse whose duration is shorter as the number of input terminals decreases as shown in FIG. The duration becomes longer. As a result, comparator 240
Transistors 241 and 242 controlled by the output signal of
As a result, the voltage supplied to the motor 31 decreases, and the rotation speed of the motor 31 decreases as the vehicle speed increases.

Further, as the vehicle speed increases and reaches a second vehicle speed, the voltage supplied to the non-inverting input terminal of comparator 144 of comparator circuit 140 becomes greater than the voltage supplied to the inverting input terminal, and comparator 144 generates a motor disconnect signal. Therefore, the transistor 203 is turned off, so the current from the transistor 203 is no longer supplied to the resistor 207K, and the transistor 204 is turned on. When the transistor 204 turns on, the resistor 21
The voltage at the connection point of 1 and 212 is shorted to ground, but o
Since the voltage of the capacitor 217 is supplied to the inverting input terminal of the P amplifier 219, K does not immediately become the same potential as the ground, but gradually decreases. Since the output voltage of the op amp 219 changes in phase opposite to the phase of the voltage change supplied to the inverting input terminal, a gradually increasing voltage is supplied to the non-inverting input terminal of the comparator 240. As described above, the comparator 240 operates such that the duration of the output signal increases as the voltage supplied to the non-inverting input terminal increases. Therefore, the duration of the output signal from the comparator 240 gradually becomes shorter, and accordingly, the voltage supplied to the motor 31 via the transistors 241 and 242 decreases, and the rotational speed of the motor 31 gradually decreases. .

Therefore, in a low speed range, the motor 31 starts operating when the vehicle speed reaches the first speed, and its rotation speed gradually increases, and after reaching a predetermined rotation speed, the rotation speed decreases as the vehicle speed increases. do. Then, when the vehicle speed reaches the second speed, the motor 31 gradually decreases in rotation speed and stops operating according to the characteristics determined by the output signal of the signal generator 210. In this way, since the rotation speed changes slowly when one motor starts and stops, the effect of power steering also changes gradually.
Even if the motor 31 starts or stops during steering, the steering force does not suddenly change, so a smooth steering feeling can be obtained, and since the steering force originally decreases as the vehicle speed increases. As shown in Fig. 5, the steering force in the low speed range from the first speed v1 to the second speed v2 is kept constant by decreasing the motor rotation speed as the vehicle speed increases. I can do it. If the motor 3 is kept operating at all times in the low speed range as described above, there is no delay in response to steering, resulting in good steering followability. Note that since FIG. 5 is a diagram that does not include a time element, the motor rotational speed changes suddenly at vehicle speeds v1 and v2. However, as mentioned above, the actual motor rotation speed gradually reaches a predetermined value over a period of about one second.When the vehicle speed is in the high speed range, the motor 31 does not operate and power steering is not performed. Since the steering force only needs to be small when the vehicle speed is high, there is no problem even if power steering is not performed8.Furthermore, if an excessive current flows to the motor 31 for some reason, the relay 267 of the overcurrent protection circuit 260 is activated. operates, and relay contact 268 turns on, so transistor 2
42 is protected from excessive current. At this time, the motor current is not controlled by the transistor 242, so voltage continues to be supplied to the motor 31 even if the vehicle speed is in the low speed range or the second speed, and the motor 31 is only supplied when the motor current falls below a predetermined value. ■Pressure is no longer supplied.

In the embodiment, the signal generator 210 and the voltage regulator 230 generate continuous signals, but the signal generator 210 can be changed within a practical range by combining a resistor and a relay, for example. The output signal may be changed in steps. Still, comparator song, road 130
If you delete this and short-circuit the circuit between the emitter and collector of the transistor 202, the motor 31 will operate when the vehicle is stopped and steering is being performed, and the motor 31 will operate in the very low speed range and low speed range regardless of the steering. However, in a high speed range, the motor 31 can be stopped regardless of the steering operation. Furthermore, the steering angle sensor 101 may detect the steering torque of the steering shaft, and the combination circuit of the F7V conversion circuit and the following comparator circuit may be replaced with a timer.

As explained above, the power steering device according to the present invention gradually increases the rotation speed of the motor when operating the motor,
When stopping a motor that has been operating, the rotational speed of the motor is gradually reduced, so even if the motor jerks or comes to a standstill during steering, the steering force will not change suddenly. , stable steering is possible, and since the motor is started using an intermittent signal whose duration gradually increases, the motor starting current is small, and the ratings of the parts used in the circuit through which the starting current flows can be reduced. Therefore, it has an excellent effect of improving economic efficiency.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of the present invention, Fig. 2 is its circuit diagram, Fig. 3 is a waveform diagram of each part, Fig. 4 is a graph showing the increasing characteristics of the motor rotation speed, and Fig. 5 is the motor It is a graph showing the change characteristics of the rotation speed. 1.00. Sensor, 211111111 control circuit, 3゜@*@motor circuit, 31----m motor, 100-...
・Vehicle speed sensor, 101... Steering angle sensor, 110
, 120... Frequency/voltage converter (F-V converter)
, 130, 140, 150--Comparator circuit, 200--Switch circuit, 210--Q signal generator, 230--Voltage regulator, 250--Vehicle speed sensitive circuit, 260--・φ・Overcurrent protection circuit, Patent applicant: Jidosha Kiki Co., Ltd. Agent: Masaki Yamakawa (and 1 other person) Figure 3 Figure 5

Claims (1)

[Claims] In a power steering device that controls a motor based on the output of a sensor that detects the running state and drives an oil pump by the motor, when the signal output from the sensor is a signal for operating the motor, the motor is activated. A power steering device comprising a control circuit that gradually increases the rotational speed of the motor and gradually decreases the rotational speed of the motor when a signal output from the sensor is for stopping the motor. .