JP3484617B2 - Electric power steering device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention drives and controls a steering force assisting motor on the basis of the detected torque detected by a torque sensor, and when the detected torque is within a predetermined range, the steering force in the direction opposite to the detected torque. The present invention relates to an improvement in an electric power steering device that prohibits driving of an auxiliary motor.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram showing a schematic configuration of an example of a conventional electric power steering apparatus. In this electric power steering apparatus, the CPU 2 determines a motor current target value of the steering force assisting motor 4 based on the detected torque detected by the torque sensor 1, and uses the motor current target value as a target value for automatic control. 3 is driven to drive the motor 4, and at that time, the drive current of the motor 4 detected by the motor current detection circuit 5 is input to the CPU 2 as a feedback value for automatic control. The detected torque detected by the torque sensor 1 is also input to the direction prohibited area determination circuit 8, and the direction prohibited area determination circuit 8 is shown in FIG.
When the detected torque is larger than a predetermined value in each of the left and right directions, a motor drive prohibition region in which the motor 4 is not driven in the direction opposite to the detected torque is set. The drive prohibiting circuit 14 prohibits driving in the direction opposite to the detected torque of the motor 4 to prevent rotation of the steering wheel and reverse assist (assisting steering force in the reverse direction) when the CPU 2 runs out of control.

[0003]

However, when the CPU 2 runs out of control, prohibition / permission of the motor drive is determined by the value of the detected torque, which causes the following problems. The motor drive prohibition circuit 14 allows only excessive assist in the same direction as the detected torque. Therefore, when the steering wheel is operated and the steering force leaves the dead zone, assistance is provided. At this time, if the steering force is small, the assisted detection torque decreases. When the detected torque decreases, the dead zone is entered, and the assist is turned off. Since the assist is turned off, the steering force increases. It is assisted when the steering force increases and goes out of the dead zone. By repeating the above, steering becomes unstable. In addition, it is not possible to perform the steering wheel return control within the dead zone.

The present invention has been made in view of the above circumstances, and in the first invention, a non-driving detection circuit for detecting that the motor current target value is zero and a direction opposite to the detected torque. By providing a drive prohibition holding circuit that holds the motor drive prohibition state until the non-drive detection circuit detects zero, when the CPU runs away, assist and assist prohibition are repeated, and steering becomes unstable. An object of the present invention is to provide an electric power steering device that can prevent the occurrence of According to the second aspect of the present invention, by providing the drive abnormality detection circuit for detecting the state where the detected torque is outside the dead zone and the motor current target value indicates a direction opposite to the detected torque,
An object of the present invention is to provide an electric power steering device in which steering is stable even when the CPU runs out of control. According to the third aspect of the present invention, the steering torque is stable even when the CPU goes out of control by providing the drive abnormality detection circuit for detecting the state where the detected torque is within the dead zone and the drive current of the motor is larger than the predetermined value. At the same time, it is an object of the present invention to provide an electric power steering device capable of performing return control of a steering wheel.

According to the fourth aspect of the invention, the drive abnormality detection circuit detects a state where the detected torque is outside the dead zone and the motor current target value indicates a direction opposite to the detected torque, and the drive abnormality detection circuit detects the state. In this case, by providing a detection timer that starts counting the first predetermined time and is reset when the drive abnormality detection circuit stops detecting the above state, it is resistant to noise and even when the CPU runs out of control. An object of the present invention is to provide an electric power steering device that is stable in steering. According to the fifth aspect of the invention, the drive abnormality detection circuit detects a state in which the detected torque is within the dead zone and the drive current of the motor is larger than a predetermined value, and when the drive abnormality detection circuit detects the state, the first abnormality is detected. By providing a detection timer that starts counting a predetermined time and is reset when the drive abnormality detection circuit stops detecting the above-mentioned state, it is resistant to noise and the steering is stable even when the CPU runs out of control. It is an object of the present invention to provide an electric power steering device that can control the return of the steering wheel.

In the sixth aspect of the invention, when the drive abnormality detection circuit detects the above-mentioned state, the second predetermined time is started to be counted,
A confirmation timer that is reset when the drive abnormality detection circuit no longer detects the above state, and a fail that connects the motor drive circuit and the power supply when the confirmation timer completes measuring the second predetermined time. By providing a relay drive prohibition circuit that turns off the relay, it is resistant to noise and CPU
It is an object of the present invention to provide an electric power steering device in which steering is stable even when the vehicle runs out of control. According to the seventh aspect of the invention, by providing the indicator lamp that lights up when the drive prohibition holding circuit holds the drive prohibition state of the motor, and lights up when the abnormality detection signal holding circuit holds the abnormality detection signal, An object of the present invention is to provide an electric power steering device that can inform the driver of the situation when the CPU runs out of control.

[0007]

According to a first aspect of the present invention, an electric power steering apparatus determines a motor current target value of a steering force assisting motor on the basis of detected torque detected by a torque sensor, and automatically sets the motor current target value. Set the control target value,
In an electric power steering device that drives the motor as a feedback value of automatic control, controls the drive of the motor, and prohibits driving of the motor in a direction opposite to the detected torque when the detected torque is within a predetermined range, A non-drive detection circuit that detects that the motor current target value is zero, and a drive prohibition that holds the drive prohibition state of the motor in the direction opposite to the detected torque until the non-drive detection circuit detects the zero. And a holding circuit.

In the electric power steering apparatus according to the second aspect of the present invention, the dead zone detection circuit for detecting the dead zone of the detected torque which should set the motor current target value to zero, and the detected torque being outside the dead zone, A drive abnormality detection circuit for detecting a state in which the target value indicates a direction opposite to the detected torque, and when the drive abnormality detection circuit detects the state, the drive of the motor is prohibited. And

In the electric power steering apparatus according to the third aspect of the present invention, the drive abnormality detection circuit detects that the detected torque is within the dead zone and the drive current of the motor is larger than a predetermined value, and the drive abnormality is detected. When the detection circuit detects the above state, the driving of the motor is prohibited.

In the electric power steering apparatus according to the fourth aspect of the present invention, the dead zone detection circuit for detecting the dead zone of the detected torque which should set the motor current target value to zero, and the detected torque being outside the dead zone, A drive abnormality detection circuit that detects a state in which the target value indicates a direction opposite to the detected torque, and when the drive abnormality detection circuit detects the state,
A timer for detection that starts counting a first predetermined time and is reset when the drive abnormality detection circuit stops detecting the state, and the timer for detection completes the measurement of the first predetermined time. In this case, the driving of the motor is prohibited.

In the electric power steering apparatus according to the fifth aspect of the present invention, the detection timer includes the drive abnormality detection circuit,
When the detected torque is within the dead zone and the state in which the drive current of the motor is larger than the predetermined value is detected, the first predetermined time period is started to be counted, and the drive abnormality detection circuit detects the state. When it disappears, it is reset, and when the detection timer completes the measurement of the first predetermined time, the driving of the motor is prohibited.

In the electric power steering apparatus according to the sixth aspect of the invention, when the drive abnormality detection circuit detects the state, the second predetermined time period starts to be clocked, and the drive abnormality detection circuit detects the state. A confirming timer that is reset when it runs out, and an abnormality detection signal holding circuit that retains an abnormality detecting signal from the drive abnormality detecting circuit when the confirming timer completes measuring a second predetermined time, A relay drive prohibition circuit for turning off a fail relay that connects the drive circuit of the motor and a power source while the abnormality detection signal holding circuit holds the abnormality detection signal is provided.

In the electric power steering apparatus according to the seventh aspect of the present invention, the electric power steering device is turned on when the drive prohibition holding circuit holds the drive prohibition state of the motor, and the abnormality detection signal holding circuit holds the abnormality detection signal. It is characterized in that it is provided with an indicator light that lights up when the display is on.

[0014]

In the electric power steering apparatus according to the first aspect of the invention, the drive prohibition holding circuit holds the motor drive prohibition state in the direction opposite to the detected torque until the non-drive detection circuit detects the motor current target value of zero. . Therefore, even when the CPU goes out of control and the motor current target value becomes excessive, rotation and reverse assist of the steered wheels due to excessive motor current flowing are prevented. Further, it is possible to prevent the steering from becoming unstable by repeating the assist and the prohibition of the assist due to the CPU runaway.

In the electric power steering apparatus according to the second aspect of the present invention, the drive abnormality detection circuit detects that the dead zone detection circuit detects that the detected torque is out of the dead zone range and the motor current target value indicates a direction opposite to the detected torque. When is detected, the drive of the motor is prohibited.

In the electric power steering apparatus according to the third aspect of the present invention, the drive abnormality detection circuit drives the motor when the detected torque is within the dead zone and the drive current of the motor is larger than a predetermined value. Ban.

In the electric power steering apparatus according to the fourth aspect of the present invention, when the dead zone detection circuit detects that the detected torque is outside the dead zone, the drive abnormality detection circuit,
When the state where the motor current target value indicates a direction opposite to the detected torque is detected, the detection timer starts counting the first predetermined time, and is reset when the drive abnormality detection circuit stops detecting the state. It The detection timer is the first
When the time measurement of the predetermined time is completed, the driving of the motor is prohibited.

In the electric power steering device according to the fifth aspect of the invention, when the dead zone detection circuit detects that the detected torque is within the dead zone, the drive abnormality detection circuit
When the state in which the drive current of the motor is larger than the predetermined value is detected, the detection timer starts counting the first predetermined time,
It is reset when the drive abnormality detection circuit stops detecting the above state. Then, when the detection timer completes the counting of the first predetermined time, the drive of the motor is prohibited.

In the electric power steering apparatus according to the sixth aspect of the present invention, when the drive abnormality detection circuit detects a state where the detected torque is outside the dead zone and the motor current target value indicates a direction opposite to the detected torque, it is determined. The timer for use starts counting the second predetermined time, and is reset when the drive abnormality detection circuit stops detecting the state. When the confirmation timer completes measuring the second predetermined time, the abnormality detection signal holding circuit holds the abnormality detection signal from the drive abnormality detection circuit, and while the abnormality detection signal holding circuit holds the abnormality detection signal, The relay drive inhibition circuit turns off the fail relay that connects the motor drive circuit and the power supply, and suspends the steering force assistance.

In the electric power steering apparatus according to the seventh aspect of the invention, the indicator lamp lights up while the drive prohibition holding circuit holds the motor drive prohibited state, and the abnormality detection signal holding circuit holds the abnormality detection signal. Lights up when

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing its embodiments. FIG. 1 is a block diagram showing the configuration of an embodiment of an electric power steering apparatus according to the first to sixth inventions of the present invention. This electric power steering device uses a CPU based on the detected torque detected by the torque sensor 1.
2 determines the motor current target value of the steering force assisting motor 4,
Using this motor current target value as the target value for automatic control, the motor drive circuit 3 is controlled to drive the motor 4, and at that time,
The drive current of the motor 4 detected by the motor current detection circuit 5 is input to the CPU 2 as a feedback value for automatic control.

The detected torque detected by the torque sensor 1 is also input to the direction prohibited area determination circuit 8a, and the direction prohibited area determination circuit 8a has a predetermined detected torque in each of the left and right directions, as shown in FIG. When the value is larger than the value, a motor drive prohibition region in which the motor 4 is not driven is set in the direction opposite to the detected torque, and whether the detected torque is in this motor drive prohibition region or not is determined by a drive logic determination circuit 9 described later. And the dead zone detection circuit 10 is notified. The detection signal of the dead zone detection circuit 10 is given to the abnormal current determination circuit 6 which determines that the detected torque is within the dead zone and the drive current of the motor is larger than a predetermined value. Here, the predetermined value of the drive current of the motor is larger than the maximum value of the return current of the steered wheels, and is set to a value that does not put the electric power steering device in a dangerous state. The motor current target value (magnitude and direction) is sent from the CPU 2 to the motor drive circuit 3, the drive logic determination circuit 9, and a non-drive detection circuit 11 described later.

The determination results of the drive logic determination circuit 9 and the abnormal current determination circuit 6 for determining that the detected torque is outside the dead zone and the motor current target value indicates the opposite direction to the detected torque are the drive abnormality detection circuit 7 When the drive abnormality detection circuit 7 detects an abnormality from these determination results,
Timing of the predetermined times T1 and T2 of the detection timer 12 and the confirmation timer 15 is started. When the detection timer 12 completes counting the predetermined time T1, the latch circuit 13 holds the abnormality detection signal from the drive abnormality detection circuit 7. While the latch circuit 13 holds the abnormality detection signal from the drive abnormality detection circuit 7, the diagnostic lamp 19 lights up and the motor drive prohibition circuit 14 stops the operation of the motor drive circuit 3.

The latch circuit 13 is cleared when the non-drive detection circuit 11 which detects that the motor current target value is zero detects zero. When the confirmation timer 15 completes counting the predetermined time T2, the latch circuit 16 holds the abnormality detection signal from the drive abnormality detection circuit 7. While the latch circuit 16 holds the abnormality detection signal from the drive abnormality detection circuit 7, the diagnostic lamp 19 lights up and
The relay drive inhibition circuit 17 turns off the fail relay 18 that connects the motor drive circuit 3 and the power supply.

The operation of the electric power steering device having such a configuration will be described below. The detected torque detected by the torque sensor 1 is input to the direction prohibited area determination circuit 8a,
The direction prohibited area determination circuit 8a determines the direction and magnitude of the detected torque, and a signal indicating the detected torque direction is sent to the drive logic determination circuit 9. As for the magnitude of the detected torque, as shown in FIG. 2, the magnitude of the detected torque with respect to the left and right directions is larger than a predetermined value (whether within the dead zone or outside the dead zone).
Is sent to the dead zone detection circuit 10. From the dead zone detection circuit 10, a notification signal indicating whether the detected torque is within the dead zone or outside the dead zone is output.
Sent to.

Here, the drive logic determination circuit 9 notifies the drive abnormality detection circuit 7 of the abnormality during the period in which the detected torque is outside the dead zone and the motor current target value shows the opposite direction to the detected torque. Further, the abnormal current determination circuit 6 continues to notify the drive abnormality detection circuit 7 of the abnormality while the detected torque is within the dead zone and the motor drive current is larger than a predetermined value. The drive abnormality detection circuit 7 includes a drive logic determination circuit 9
Alternatively, when an abnormality is notified from the abnormal current determination circuit 6, the detection timer 12 and the confirmation timer 15 are activated, and when the abnormality notification from the drive logic determination circuit 9 or the abnormal current determination circuit 6 is interrupted, Timer 12 and confirmation timer 1
Reset 5. The detection timer 12 includes the drive logic determination circuit 9 or the abnormal current determination circuit 6 to the drive abnormality detection circuit 7.
When the timing of the predetermined time T1 is completed without interruption of the abnormality notification to the drive logic determination circuit 9
Alternatively, the abnormality notification from the abnormal current determination circuit 6 is held.
The latch circuit 13 turns on the diagnostic lamp 19 and activates the motor drive inhibition circuit 14 to inhibit the drive of the motor 4 while holding the abnormality notification. During this period, when the non-drive detection circuit 11 detects that the motor current target value is zero, the latch circuit 13 is cleared, the operation of the motor drive inhibition circuit 14 is stopped, and the drive inhibition of the motor 4 is released. .

In the CPU 2, the assist current and the steering wheel return current based on the torque signal are determined, and the angular velocity difference control (differential control of the torque signal) is performed. For this reason, a state in which the target current is in the opposite direction to the torque, or a large amount of the motor current flows even though the torque is in the dead zone occurs momentarily, and the CPU 2 is normal (not runaway). Nevertheless, drive abnormality may be detected. Therefore, it is necessary to set the predetermined time T1 of the detection timer 12 to be longer than the time when the drive abnormality detection circuit 7 operates in the normal state. Further, the predetermined time T1 of the detection timer 12 is
It is necessary to set within the time that can ensure the safety when the CPU 2 runs out of control. Therefore, the role of the detection timer 12 is C
It is to secure the safety by turning off the motor 4 when the CPU 2 runs out of control without erroneously detecting the CPU 2 running out of control when the PU 2 is normal.

Here, unless the non-driving detection circuit 11 detects once that the target value of the motor current is zero (non-driving), if the latch circuit 13 is not cleared, the following problems will occur. Occurs. When the CPU 2 runs out of control and the motor current target value becomes excessive, a large current flows through the motor 4 while the detection timer 12 measures the predetermined time T1 even when the detected torque is within the dead zone. , The steering wheel rotates. Since the detected torque in the direction opposite to the drive current of the motor is generated by the rotation of the steered wheels, the drive logic determination circuit 9 determines and notifies the abnormality. for that reason,
The driving of the motor 4 is prohibited, the assist is turned off, and the steered wheels return in the opposite direction. At this time, the determination of the drive logic determination circuit 9 becomes normal, and a large current flows again. Hereinafter, the same operation is repeated, and the operation of the electric power steering device becomes unstable.

The confirmation timer 15 is composed of the drive logic determination circuit 9
Alternatively, when the abnormality notification from the abnormal current determination circuit 6 to the drive abnormality detection circuit 7 is completed without interruption, the latch circuit 16 is notified of the abnormality from the drive logic determination circuit 9 or the abnormal current determination circuit 6. To hold. The latch circuit 16 maintains the diagnostic lamp 1 while holding the abnormality notification.
9 is turned on, the relay drive inhibition circuit 17 is activated, the fail relay 18 is turned off, and the motor drive circuit 3
Turn off the power. The latch circuit 16 is cleared when the power of the electric power steering device is turned off (when the ignition key is turned off). Since the detection timer 12 is reset by the motor non-driving detection of the CPU 2, the detection timer 12 may be repeatedly detected and returned depending on the runaway state of the CPU 2 and may become unstable. Therefore, the predetermined time T2 of the confirmation timer 15 is set to be sufficiently longer than the predetermined time T1 of the detection timer 12, and the predetermined time T2 is set.
If the drive abnormality continues during the period 2, the failure will be confirmed.

The drive logic determination circuit 9 determines that the drive torque is normal during the period in which the detected torque is outside the dead zone and the logic in which the target value of the motor current indicates the opposite direction to the detected torque is not established, and the drive abnormality detection circuit 7 is detected. Does not notify the abnormality. Further, the abnormal current determination circuit 6 does not notify the drive abnormality detection circuit 7 of an abnormality during the period when the detected torque is within the dead zone and the condition that the motor drive current is larger than the predetermined value is not satisfied. The drive abnormality detection circuit 7 stops the detection timer 12 and the confirmation timer 15 while no abnormality is notified from the drive logic determination circuit 9 or the abnormal current determination circuit 6. Therefore, the latch circuits 13 and 16 do not hold the abnormality notification and do not operate the motor drive prohibition circuit 14 and the relay drive prohibition circuit 17.

FIG. 3 shows the configuration of the direction prohibited area determination circuit 8a, the drive logic determination circuit 9, the dead zone detection circuit 10, the abnormal current determination circuit 6, the drive abnormality detection circuit 7 and the non-drive detection circuit 11, and FIG. FIG. 3 is a circuit diagram showing configurations of a detection timer 12, a latch circuit 13, a motor drive prohibition circuit 14, a confirmation timer 15, a latch circuit 16 and a relay drive prohibition circuit 17, respectively. The direction prohibition region determination circuit 8a includes an operational amplifier 21 to which a predetermined voltage is applied to its inverting input terminal and a torque signal to its non-inverting input terminal, and a predetermined voltage to its non-inverting input terminal and its torque signal to its inverting input terminal. Is a window comparator composed of an operational amplifier 22 provided with a voltage dividing resistor R49, R50, and R51 for generating respective predetermined voltages. The anode of the torque signal line is connected to the inverting input terminal of the operational amplifier 22. The diode D58 is connected to the collector of the NPN transistor Q34 of the clutch monitoring circuit.

The drive logic determination circuit 9 has an inverting input terminal to which the output of the operational amplifier 21 is applied, a non-inverting input terminal to which the detection signal from the motor left drive signal detecting circuit is applied, and an non-inverting input terminal. It is composed of an operational amplifier 24 to which the detection signal from the motor right drive signal detection circuit is given and the output of the operational amplifier 22 is given to the inverting input terminal. In the motor left drive signal detection circuit, the motor left drive signal is given to the base, and the base has resistors R92 and R93.
In the motor right drive signal detection circuit, the motor right drive signal is applied to the base and the base is connected to the resistors R146 and R1.
NPN transistor Q1 pulled up via 47
It is composed of three. In the non-drive detection circuit 11, the anodes are commonly connected and the cathodes are respectively connected to the transistor Q1.
It is a diode pair D61 connected to the bases of 0 and Q13, and the output is taken from the anode.

In the dead zone detection circuit 10, the output of the operational amplifier 21 is applied to the base, the base is pulled up via the resistor R53, and the collector is connected to the output terminal of the operational amplifier 23 of the abnormal current determination circuit 6 by an NPN transistor. The output of the operational amplifier 22 is given to Q39 and the base, the base is pulled up through the resistor R52, and the collector is connected to the output terminal of the operational amplifier 23 in the NPN.
It is composed of a transistor Q38. The abnormal current determination circuit 6 generates a predetermined voltage, and an operational amplifier 23 to which a predetermined voltage is applied to the inverting input terminal and a detection signal from the motor current detection circuit 5 (FIG. 1) is applied to the non-inverting input terminal. It is composed of voltage dividing resistors R106 and R107. In the drive abnormality detection circuit 7, the output of the operational amplifier 23 is given to the base through a resistor, and the collector has the operational amplifier 2
It is composed of an NPN transistor Q40 connected to the output terminals of 4, 25 and pulled up via a resistor.

The detection timer 12 has an inverting input terminal pulled up via resistors R108 and R109 and grounded via a capacitor C57, and a non-inverting input terminal supplied with a predetermined voltage given by voltage dividing resistors R110 and R111. Operational amplifier 27 and the anodes of resistors R108, R
The diode pair D62 is commonly connected to the connection node of 109, one cathode is connected to the output terminals of the operational amplifiers 24 and 25, and the other cathode is connected to the inverting input terminal of the operational amplifier 27. Latch circuit 13
The output of the operational amplifier 27 is given to the inverting input terminal,
The operational amplifier 26 is configured such that a non-inverting input terminal is provided with a divided voltage generated by a voltage dividing resistor, which is the difference voltage between the power supply and the anode voltage of the diode pair D61 of the non-driving detection circuit 11.

In the motor drive prohibiting circuit 14, the output of the operational amplifier 27 is given to the base through the resistor, the base is pulled up through the resistor, and the collector is connected to the motor drive circuit 3 (FIG. 1) by the NPN transistor Q30. It is configured. The confirmation timer 15 has a non-inverting input terminal grounded via a capacitor C58, and an inverting input terminal
The operational amplifier 28 to which a predetermined voltage given by the voltage dividing resistors R110 and R111 is applied, the anode is connected to the output terminals of the operational amplifiers 24 and 25, and the cathode is connected to the non-inverting input terminal of the operational amplifier 28, and the resistor R142 is connected.
Is connected in parallel with a diode D65.

In the latch circuit 16, the cathode of the diode D64 is connected to the base through a resistor and the collector is
An NPN transistor Q31 to which a predetermined voltage given by the voltage dividing resistors R110 and R111 is applied, and a diode pair D66 whose cathode is commonly connected to the output terminal of the operational amplifier 28 and whose one anode is connected to the inverting input terminal of the operational amplifier 28. The anode of the diode D64 is a capacitor C59 whose other end is connected to the power supply.
, And the other is connected to a connection node with a grounded resistor. The relay drive inhibition circuit 17 is composed of an NPN transistor Q37 whose base is connected to the other anode of the diode pair D66 via a resistor and an inverter 28 and whose collector is connected to the relay drive circuit.

The operation of the circuit having such a configuration will be described below. The detected torque is in the right (direction) torque area, and CP
If U2 (Fig. 1) is operating normally, operational amplifier 2
The output terminal A of 1 has a high voltage, and the inverting input terminal B of the operational amplifier 25 has a resistor R53 when the power source is 5V, for example.
And NPN transistor Q39, 2.5 to 3.5
It becomes V. When the motor left drive signal is non-driving (high voltage), the non-inverting input terminal C of the operational amplifier 25 becomes 5V.
Since the NPN transistor Q39 is on, the output terminal D of the operational amplifier 23 has a low voltage, and the NPN transistor Q40 is off.

The output terminal E of the operational amplifier 22 (the inverting input terminal F of the operational amplifier 24) has a low voltage. When the motor right drive signal is non-driving (high voltage), the non-inverting input terminal G of the operational amplifier 24 becomes 5V. When the motor drive signal is driven (low voltage), the non-inverting input terminal G of the operational amplifier 24
Are divided by resistors R146 and R147, and
It becomes 6V. Therefore, when the detected torque is in the right (direction) torque region and the CPU 2 (FIG. 1) is operating normally, the output terminals H (outputs of the drive logic determination circuit 9) of the operational amplifiers 24 and 25 are at a high voltage. Has become.

When the detected torque is in the right (direction) torque region and the operation of the CPU 2 (FIG. 1) is abnormal, the output terminal A of the operational amplifier 21 becomes a high voltage and the operational amplifier 25
The inverting input terminal B of is set to 2.5 to 3.5V by the resistor R53 and the NPN transistor Q39. When the motor left drive signal is driven (low voltage), the non-inverting input terminal C of the operational amplifier 25 becomes 1.6 V due to the divided voltage by the resistors R92 and R93. Therefore, the detected torque is right (direction)
In the torque region, when the operation of the CPU 2 (FIG. 1) is abnormal, the operational amplifier 24,
The output terminal H of 25 (the output of the drive logic determination circuit 9) is at a low voltage.

When the detected torque is in the dead zone, the output terminal A of the operational amplifier 21 and the output terminal E of the operational amplifier 22 (the output of the direction prohibition area determination circuit 8a) are at a low voltage. Regardless of the signal, the output terminals H of the operational amplifiers 24 and 25 (the output of the drive logic determination circuit 9) are at a high voltage, and no drive logic abnormality is detected. When the motor drive current detected by the motor current detection circuit 5 is smaller than the value (for example, 10 A) determined by the resistors R106 and R107, the output terminal D of the operational amplifier 23 becomes a low voltage and the NPN transistor Q40 is turned off. Therefore, the output terminals H of the operational amplifiers 24 and 25
(The output of the drive logic determination circuit 9) becomes a high voltage, and the drive logic abnormality is not detected. When the motor drive current detected by the motor current detection circuit 5 is larger than a value (for example, 10 A) determined by the resistors R106 and R107, the operational amplifier 23
Output terminal D becomes high voltage, and NPN transistor Q4
0 turns on. Therefore, the output terminals H of the operational amplifiers 24 and 25 (the output of the drive logic determination circuit 9) are at a low voltage regardless of other conditions, and the drive logic abnormality is detected.

When the clutch is off, the NPN transistor Q34 of the clutch monitoring circuit is turned on and the torque signal to the window comparator composed of the operational amplifier 21 and the operational amplifier 22 becomes a low voltage, so that the motor is forcibly driven to the left. Allowed and motor lock check is possible.

An abnormal drive logic is detected, and the operational amplifier 2
When the output terminals H (output of the drive logic determination circuit 9) of 4, 25 become low voltage, the electric charge stored in the capacitor C57 of the detection timer 12 (FIG. 1) is discharged through the resistor R109 (detection time). Decision). When the inverting input terminal I of the operational amplifier 27 becomes lower than the voltage of the non-inverting input terminal J of the operational amplifier 27 determined by the resistors R110 and R111, the output terminal K of the operational amplifier 27 (output of the detection timer 12) becomes high voltage. , The NPN transistor Q30 is turned on, and the motor 4 is connected through the motor drive circuit 3 (FIG. 1) connected to the collector of the NPN transistor Q30.
Driving is prohibited.

Once the output terminal K of the operational amplifier 27 (the output of the detection timer 12) becomes a high voltage, the operational amplifier 26 of the latch circuit 13 (FIG. 1) is maintained while the motor drive signal is in the drive state (low voltage). Inverting input terminal K (operational amplifier 2
7 has a higher voltage than the non-inverting input terminal L of the operational amplifier 26. Therefore, the output terminal M of the operational amplifier 26 becomes a low voltage, and even if the output terminal H of the operational amplifiers 24 and 25 (output of the drive logic determination circuit 9) returns to a high voltage, the inverting input terminal K of the operational amplifier 26 ( The output terminal K) of the operational amplifier 27 is held at a high voltage. When the drive logic abnormality is no longer detected and the output terminal H of the operational amplifiers 24 and 25 (the output of the drive logic determination circuit 9) becomes a high voltage, the resistor R108 and the diode pair D62 cause
The capacitor C57 is charged. The time constant during charging is set sufficiently smaller than the time constant during discharging.

When the motor driving signal is in the non-driving state (high voltage), the non-inverting input terminal L of the operational amplifier 26 of the latch circuit 13 becomes 5V, and the inverting input terminal K of the operational amplifier 26 is set.
The voltage (the output terminal K of the operational amplifier 27) becomes lower than that of the non-inverting input terminal L of the operational amplifier 26. Therefore, the voltage of the inverting input terminal I of the operational amplifier 27 (the output terminal M of the operational amplifier 26) depends on the voltage of the output terminals H of the operational amplifiers 24 and 25 (the output of the drive logic determination circuit 9), and the operational amplifier 24, When the output terminal H of 25 is at a high voltage, the prohibition of driving the motor 4 is released.

An abnormal drive logic is detected, and the operational amplifier 2
When the output terminals H (output of the drive logic determination circuit 9) of 4, 25 become low voltage, the electric charge stored in the capacitor C58 of the confirmation timer 15 (FIG. 1) is discharged through the resistor R142 (determination time determination). ). When the non-inverting input terminal N of the operational amplifier 28 becomes lower in voltage than the inverting input terminal J of the operational amplifier 28, the output terminal O of the operational amplifier 28 becomes low voltage and the NPN transistor Q37 of the relay drive inhibition circuit 17 (FIG. 1) is turned on. Then, the operation of the fail relay 18 (FIG. 1) is prohibited (the power supply of the motor drive circuit 3 is turned off).

When the output terminal O of the operational amplifier 28 becomes a low voltage, the non-inverting input terminal N of the operational amplifier 28 drops to a voltage corresponding to the forward voltage of the diode pair D66, which is lower than the inverting input terminal J of the operational amplifier 28. Become a voltage. Therefore, the output terminal O of the operational amplifier 28 is maintained at a low voltage (fault state is determined). When the electric power steering device starts up (when the ignition key is turned on),
The NPN transistor Q31 of the latch circuit 16 is momentarily turned on by the differential signal from the capacitor C59 when the power supply 5V rises, and the inverting input terminal J of the operational amplifier 28 is turned on.
Becomes a low voltage. Therefore, the output terminal O of the operational amplifier 28 becomes a high voltage, during which the confirmation timer 15 (FIG. 1).
Capacitor C58 is charged.

[0047]

According to the electric power steering apparatus according to the first and second aspects of the present invention, when the CPU goes out of control, the electric power steering apparatus can be repeatedly prevented from becoming unstable by repeating the assist and the prohibition of the assist. it can.

According to the electric power steering apparatus of the third aspect of the present invention, when the CPU runs out of control, the assist and the assist prohibition are repeated to prevent the steering from becoming unstable, and the steering wheel return control can be performed. It is possible to realize an electric power steering device that can be used.

According to the electric power steering apparatus of the fourth and sixth inventions, the electric power steering apparatus is resistant to noise and can prevent the steering from becoming unstable by repeating the assist and the prohibition of the assist when the CPU runs out of control. Can be realized. Further, the runaway of the CPU can be monitored without disturbing the differential control of the torque signal.

According to the electric power steering apparatus of the fifth aspect of the present invention, it is resistant to noise, and when the CPU runs out of control, it is possible to prevent the steering from becoming unstable by repeating the assistance and the inhibition of the assistance. It is possible to realize an electric power steering device that can perform Further, the runaway of the CPU can be monitored without disturbing the differential control of the torque signal.

According to the electric power steering apparatus of the seventh aspect of the present invention, it is possible to realize an electric power steering apparatus which can inform the driver of the situation when the CPU runs out of control.

[Brief description of drawings]

FIG. 1 is an electric power steering device 1 according to the present invention.
It is a block diagram showing a schematic structure of an example.

FIG. 2 is a graph showing the relationship between the detected torque and the motor current target value of the electric power steering device according to the present invention.

FIG. 3 is a circuit diagram showing a specific configuration of an electric power steering device according to the present invention.

FIG. 4 is a circuit diagram showing a specific configuration of the electric power steering device according to the present invention.

FIG. 5 is a block diagram showing a schematic configuration of an example of a conventional electric power steering device.

FIG. 6 is a graph showing a relationship between a detected torque of a conventional electric power steering device and a motor current target value.

[Explanation of symbols]

2 CPU 3 Motor drive circuit 4 motor 5 Motor current detection circuit 6 Abnormal current determination circuit 7 Drive abnormality detection circuit 8a Direction prohibited area determination circuit 9 Drive logic judgment circuit 10 Dead band detection circuit 11 Non-driving detection circuit 12 Detection timer 13 Latch circuit (drive prohibition holding circuit) 14 Motor drive prohibition circuit 15 Confirmation timer 16 Latch circuit (abnormality detection signal holding circuit) 17 Relay drive prohibition circuit 18 Fail Relay 19 diagnostic lights

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-137651 (JP, A) JP-A-7-17424 (JP, A) JP-A-7-17423 (JP, A) JP-A-5- 112251 (JP, A) JP 4-31171 (JP, A) JP 2-274658 (JP, A) JP 2-293259 (JP, A) JP 5-97042 (JP, A) JP-A-5-112250 (JP, A) Actual development Sho 63-154384 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) B62D 5/04 B62D 6/00

Claims (7)

(57) [Claims] 1. A motor current target value of a steering force assisting motor is determined based on the detected torque detected by a torque sensor,
The motor current target value is set as a target value for automatic control, the drive current of the motor is set as a feedback value for automatic control, and the motor is drive-controlled. When the detected torque is within a predetermined range, In an electric power steering device that prohibits driving of the motor, a non-driving detection circuit that detects that the motor current target value is zero, and a state that the driving of the motor is prohibited in a direction opposite to the detected torque is set to the non-driving state. An electric power steering apparatus comprising: a drive prohibition holding circuit that holds the detection circuit until it detects the zero. 2. A dead zone detection circuit for detecting a dead zone of a detected torque for which the motor current target value should be zero, and the detected torque is outside the dead zone, and the motor current target value is in a direction opposite to the detected torque. 2. The electric power according to claim 1, further comprising: a drive abnormality detection circuit that detects the state shown, wherein the drive of the motor is prohibited when the drive abnormality detection circuit detects the state. Steering device. 3. The drive abnormality detection circuit detects a state where the detected torque is within the dead zone and the drive current of the motor is larger than a predetermined value, and the drive abnormality detection circuit detects the state. The electric power steering apparatus according to claim 2, wherein the drive of the motor is prohibited. 4. A dead zone detection circuit for detecting a dead zone of a detected torque for which the motor current target value should be zero, and the detected torque is outside the dead zone, and the motor current target value is in a direction opposite to the detected torque. A drive abnormality detection circuit for detecting the state shown, and when the drive abnormality detection circuit detects the state, when the first predetermined time period is started and the drive abnormality detection circuit stops detecting the state. 2. A detection timer that is reset is provided, and when the detection timer completes counting the first predetermined time, the drive of the motor is prohibited. Electric power steering device. 5. The first predetermined value is detected when the drive abnormality detection circuit detects that the detected torque is within the dead zone and the drive current of the motor is larger than a predetermined value. When the time measurement is started and the drive abnormality detection circuit stops detecting the state, the time is reset, and when the detection timer completes the time measurement of the first predetermined time, the drive of the motor is prohibited. The electric power steering device according to claim 4, wherein the electric power steering device is provided. 6. When the drive abnormality detection circuit detects the state, a second predetermined time is started, and when the drive abnormality detection circuit stops detecting the state, the determination is reset. When the timer and the confirmation timer have completed counting the second predetermined time, the abnormality detection signal holding circuit for holding the abnormality detection signal from the drive abnormality detection circuit and the abnormality detection signal holding circuit detect the abnormality. The electric power steering apparatus according to claim 2, further comprising: a relay drive inhibition circuit that turns off a fail relay that connects a drive circuit of the motor and a power source while holding a signal. 7. An indicator lamp that lights up when the drive prohibition holding circuit holds the drive prohibition state of the motor, and lights up when the abnormality detection signal holding circuit holds an abnormality detection signal. 7. The method according to claim 6, further comprising:
The electric power steering device described.