JP2003182607A - Electric power steering controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering controller that can reliably prevent a degradation in a steering feeling against the occurrence of a short circuit fault. <P>SOLUTION: A normal rotation monitor input terminal P3 of a CPU 21 is connected to a signal line L3 interconnecting an inverting circuit 22 and an H-bridge drive circuit 23. The CPU 21 receives an input of an inverted normal rotation drive control signal Ua as a normal rotation monitor signal Ms1 from the normal rotation monitor input terminal P3. According to a fail- safe program, the CPU 21 compares the normal rotation drive control signal Ua and the normal rotation monitor signal Ms1. If the CPU 21 determines a short circuit in a pull-up resistor R3 by the comparison of the normal rotation drive control signal Ua and the normal rotation monitor signal Ms1, the CPU 21 sets a normal rotation and a reverse rotation output terminal P1 and P2 both to an L level. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering controller.

[0002]

2. Description of the Related Art An automobile is equipped with an electric power steering control device for assisting the operating force when operating a steering wheel. The electric power steering control device has four switching elements (two switching elements for forward rotation and two switching elements for reverse rotation).
The drive source is a DC motor connected to the H-shaped bridge circuit.

Then, the CPU inputs detection signals of various sensors such as a torque detection sensor, a vehicle speed sensor, an operation direction detection sensor, and generates a drive control signal for driving and controlling the DC motor based on the signals. That is, CPU
Inputs the detection signal from each sensor, obtains the duty ratio for achieving the optimum assist force for the steering operation state and the traveling state of the vehicle at that time, and generates the drive control signal of the obtained duty ratio . The generated drive control signals are of two channels, and the normal rotation drive control signal is output from the normal rotation output terminal and the reverse rotation drive control signal is output from the reverse rotation output terminal.

When the DC motor is normally rotated,
The CPU deactivates the reverse rotation output terminal (for example, H level), and outputs the normal rotation drive control signal having a predetermined duty ratio from the normal rotation output terminal. When the DC motor is rotated in the reverse direction, the CPU deactivates the output terminal for normal rotation (for example, H level), and outputs the drive control signal for normal rotation having a predetermined duty ratio from the output terminal for reverse rotation.

The forward rotation and reverse rotation drive control signals output from the CPU are level-inverted via an inversion circuit (inverter circuit) and output to the H-bridge drive circuit. This drive circuit controls ON / OFF of four switching elements based on the inverted drive control signals for forward rotation and reverse rotation.

That is, when the DC motor rotates in the normal direction, the drive circuit turns on / off the two normal rotation switching elements at a predetermined duty ratio based on the normal rotation drive control signal.
At this time, the drive circuit holds the two reverse rotation switching elements in the OFF state based on the reverse rotation drive control signal held at the inverted H level. The DC motor is driven in the normal direction by turning on and off the two switching elements for the normal rotation at a predetermined duty ratio.

On the other hand, during the reverse rotation of the DC motor, the drive circuit turns the two reverse switching elements on and off at a predetermined duty ratio based on the reverse drive control signal. At this time, the drive circuit holds the two normal rotation switching elements in the off state based on the normal rotation drive control signal held at the inverted H level. By turning on / off the two reverse switching elements at a predetermined duty ratio,
The DC motor is driven in reverse.

That is, the CPU drives and controls the DC motor in accordance with the operation of the steering wheel and the traveling state to apply the steering torque to the steering wheel to realize the steering feeling of the steering wheel.

By the way, for example, when traveling by operating a steering wheel for driving a direct current motor to rotate normally,
U makes the output terminal for reverse rotation inactive (H level),
A normal rotation drive control signal having a predetermined duty ratio is output from the normal rotation output terminal.

In this state, if the signal line for transmitting the inversion drive control signal connecting the inversion circuit and the drive circuit short-circuits with the plus terminal of the control power supply for some reason, the inversion drive control signal is input. The input terminal of the drive circuit becomes H level. As a result, the two reverse rotation switching elements are turned on despite the fact that the two forward rotation switching elements are on / off controlled, and the DC motor malfunctions. This malfunction is not desirable because it directly affects the steering operation feeling.

Therefore, the drive circuit simultaneously sets the H level to the respective input terminals to which the forward and reverse drive control signals are respectively input.
When a level signal is input, it has a fail-safe function of turning off all the forward and reverse switching elements to stop the DC motor. As a result, the driver can operate the steering with only the operating force of the driver.

[0012]

However, when the steering is traveling in the neutral position and the short-circuit failure occurs, the DC motor must rotate even though it must be stopped. A steering torque contrary to the above is applied to the steering wheel. That is, since the CPU does not operate the steering wheel, the CPU makes the forward rotation output terminal and the reverse rotation output terminal inactive (H level). A signal is input to the level. At this time, when an H level signal is input to either one of the input terminals due to a short circuit failure, the drive circuit rotates the DC motor in one direction in response to the H level signal. as a result,
An undesired steering torque is applied to the steering, which deteriorates the steering feeling.

The present invention has been made in order to solve the above problems, and an object thereof is an electric power steering control device capable of surely preventing deterioration of steering feeling against occurrence of a short circuit failure. To provide.

[0014]

According to a first aspect of the present invention, an electric motor for applying a steering torque to a steering wheel, a forward rotation switching element for driving the electric motor in the forward direction, and a reverse rotation of the electric motor. A reverse rotation switching element for driving, a control circuit for generating a normal rotation control signal for driving the electric motor in the normal direction, and a reverse rotation control signal for driving the electric motor in the reverse direction, and the normal rotation control A signal is input through the forward rotation signal line to control the forward rotation switching element, the reverse rotation control signal is input through the reverse rotation signal line to control the reverse rotation switching element, and the forward rotation control signal and the reverse rotation control are performed. In the electric power steering control device including a drive circuit that turns off both the forward rotation and reverse rotation switching elements when signals are simultaneously input, The circuit inputs a signal transmitted to the normal rotation signal line as a normal rotation monitor signal, inputs a signal transmitted to the reverse rotation signal line as a reverse rotation monitor signal, and responds to the normal rotation control signal or the reverse rotation control signal. When different forward rotation monitor signals or reverse rotation monitor signals are output, the gist is that the forward rotation control signal and the reverse rotation control signal are simultaneously output to the drive circuit.

According to a second aspect of the present invention, in the electric power steering control device according to the first aspect, the control circuit has a normal rotation monitor signal or a reverse rotation monitor signal different from the normal rotation control signal or the reverse rotation control signal. The gist of the invention is that the normal rotation control signal and the reverse rotation control signal are simultaneously output to the drive circuit when the signal is continuously output for a predetermined time.

The invention according to claim 3 is the invention according to claim 1 or 2.
In the electric power steering control device according to the item (1), when the control circuit simultaneously outputs a normal rotation control signal and a reverse rotation control signal to the drive circuit, an output terminal that outputs the normal rotation control signal outputs a reverse rotation monitor signal. The gist of the invention is to output the reverse rotation control signal at a predetermined cycle when the input terminal for input is short-circuited.

According to a fourth aspect of the present invention, in the electric power steering control device according to any one of the first to third aspects, the control circuit causes the drive circuit to perform a forward rotation control signal and a reverse rotation control signal. When the output terminals that output the reverse rotation control signal are short-circuited with the input terminals that input the normal rotation monitor signal, the normal rotation control signal is output at a predetermined cycle. Is the gist.

According to a fifth aspect of the present invention, in the electric power steering control device according to any one of the first to fourth aspects, the electric motor is a DC motor, and the forward rotation switching element and the reverse rotation switching element. The gist is that it is connected to an H-type bridge circuit consisting of.

(Operation) According to the first aspect of the invention, when the control circuit outputs a different forward rotation monitor signal or reverse rotation monitor signal to the forward rotation control signal or the reverse rotation control signal, it outputs a signal to the drive circuit. Thus, the forward rotation control signal and the reverse rotation control signal are simultaneously output. The drive circuit stops the electric motor based on simultaneous input of the forward rotation control signal and the reverse rotation control signal.

According to the second aspect of the present invention, the control circuit causes the drive circuit to output when the normal rotation monitor signal or the reverse rotation monitor signal different from the normal rotation control signal or the reverse rotation control signal is continuously output for a predetermined time. The forward rotation control signal and the reverse rotation control signal are simultaneously output.

According to the invention of claim 3, the control circuit controls the reverse rotation at a predetermined cycle when the output terminal for outputting the normal rotation control signal and the input terminal for inputting the reverse rotation monitor signal are short-circuited. Output a signal.

According to the fourth aspect of the present invention, the control circuit is configured such that when the output terminal for outputting the reverse rotation control signal and the input terminal for inputting the normal rotation monitor signal are short-circuited, the normal rotation is performed at a predetermined cycle. Output a control signal.

According to the fifth aspect of the invention, the electric motor is a DC motor, and is connected to an H-type bridge circuit including a forward rotation switching element and a reverse rotation switching element.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an electric circuit of the electric power steering controller. The electric power steering control device 10 includes various sensor groups 11, a steering electronic control unit (steering ECU) 12,
It has a DC motor 13 for applying steering torque to a steering wheel (not shown).

The DC motor 13 has an H-type bridge circuit 15
It is connected to the. The H-type bridge circuit 15 has four F
ET elements Tr1 to Tr4 (two forward rotation FET elements Tr
1, Tr2 and two inversion FET elements Tr3, Tr4)
Is equipped with. Forward rotation FET element Tr1 and reverse rotation FET
The drain terminal of the element Tr3 is connected to the positive terminal of the battery B via the current sensor 16 and the power supply relay 17. Forward rotation FET element Tr2 and reverse rotation FET element Tr4
The source terminal of is connected to the negative terminal of the battery B via the current sensor 18.

A source terminal of the forward rotation FET element Tr1 and a drain terminal of the reverse rotation FET element Tr4 are connected to one end of the DC motor 13 via a motor relay 19.
The other end of the DC motor 13 is connected to the source terminal of the reverse rotation FET element Tr3 and the drain terminal of the normal rotation FET element Tr2.

With the reverse rotation FET elements Tr3 and Tr4 turned off, the forward rotation FET elements Tr1 and Tr2 are turned on.
The DC motor 13 is normally rotated by being turned off. The DC motor 13 is rotated in the reverse direction by turning on and off the reverse rotation FET elements Tr3 and Tr4 with the forward rotation FET elements Tr1 and Tr2 turned off.

The sensor group 11 includes a steering torque sensor,
It is composed of various sensors such as a vehicle speed sensor and an engine speed sensor, and a detection signal from each sensor is output to the ECU 12.

The ECU 12 is a CPU 2 as a control circuit.
1 is provided. CPU21 is ROM21a, RAM2
Built-in 1b. The ROM 21a stores a motor drive control program that causes the CPU 21 to execute control for applying the optimum steering torque to the steering with respect to the operating state of the steering and the running state of the vehicle.
The ROM 21a also stores a fail-safe program for causing the CPU 21 to execute drive control of the DC motor 13 when a short-circuit fault occurs.

The CPU 21 inputs the detection signal from the sensor group 11. Based on the input detection signal, the CPU 21 obtains the duty ratio for achieving the optimum assist force for the steering operation state and the traveling state of the vehicle at that time, and outputs the drive control signals Ua and Ub having the obtained duty ratio. To generate. That is, the CPU 21
Uses the motor drive control program to generate drive control signals Ua and Ub for applying to the steering wheel an optimum steering torque for the steering operation state and the traveling state of the vehicle at that time from the detection signals of the sensor group 11. .

The CPU 21 has a forward rotation output terminal P1 and a reverse rotation output terminal P2. The CPU 21 outputs the normal rotation drive control signal Ua from the normal rotation output terminal P1 and outputs the reverse rotation drive control signal Ub from the reverse rotation output terminal P2. More specifically, when the DC motor 13 is normally rotated, the CPU 2
1 is a normal rotation drive control signal Ua from the normal rotation output terminal P1.
Is output to make the reverse rotation output terminal P2 inactive (H level). On the contrary, when the DC motor 13 is rotated in the reverse direction, the CPU 21 outputs the reverse rotation drive control signal Ub from the reverse rotation output terminal P2 and deactivates the normal rotation output terminal P1 (H level).

Forward rotation output terminal P1 and reverse rotation output terminal P
Reference numeral 2 is connected to the gate terminals of N-channel FETs 22a and 22b forming the inverting circuit 22 via signal lines L1 and L2, respectively. Each of the signal lines L1 and L2 is connected to a plus terminal V + of a control power supply for reducing the voltage of the battery B to a predetermined voltage by a regulator (not shown) and supplying it via pull-up resistors R1 and R2. N channel F
The source terminals of the ETs 22a and 22b are grounded, and the drain terminals of the N-channel FETs 22a and 22b are output to the H-bridge drive circuit 23 as a drive circuit via the signal lines L3 and L4, respectively. Each signal line L3
L4 is a positive terminal V via pull-up resistors R3 and R4
Connected to +.

The H-bridge drive circuit 23 uses the normal rotation drive control signal Ua input from the CPU 21 and is inverted by the inversion circuit 22 based on the normal rotation drive control signal Ua.
Type FETs Tr1 and Tr2 for forward rotation of the bridge circuit 15
ON / OFF control. In addition, the H bridge drive circuit 23
Is the reverse drive control signal Ub input from the CPU 21.
Drive control signal Ub for reverse rotation, which has been inverted by the inversion circuit 22
Based on the above, the reverse FET elements Tr3 and Tr4 of the H-type bridge circuit 15 are on / off controlled.

The H-bridge drive circuit 23 is provided with both signal lines L
When both 3 and L4 become H level, H type bridge circuit 1
A signal for turning off all the FET elements Tr1 to Tr4 is output to the gate terminals of the FET elements Tr1 to Tr4 in order to protect the FET elements 5. That is, the H-bridge drive circuit 23 uses the forward rotation drive control signal Ua to rotate the forward rotation FET element Tr1.
When controlling Tr2 on / off, pull-up resistor R
If 4 fails and is short-circuited with the positive terminal V +, the DC motor 13 is stopped. Similarly, the H-bridge drive circuit 2
3 is a reverse FET based on the reverse drive control signal Ub
If the pull-up resistor R3 fails and is short-circuited to the plus terminal V + while the elements Tr3 and Tr4 are on / off controlled, the DC motor 13 is stopped.

The CPU 21 has a normal rotation monitor input terminal P.
3 and a reverse rotation monitor input terminal P4. The normal rotation monitor input terminal P3 is an inverted normal rotation drive control signal U connecting the inverting circuit 22 and the H-bridge driving circuit 23.
It is connected to the signal line L3 through which a is transmitted. And
The CPU 21 inputs the inverted drive control signal Ua for normal rotation from the normal rotation monitor input terminal P3 as the normal rotation monitor signal Ms1.

The reverse rotation monitor input terminal P4 is connected to the signal line L4 for transmitting the inverted reverse rotation drive control signal Ub which connects the reverse circuit 22 and the H-bridge drive circuit 23. Then, the CPU 21 inputs the inverted drive control signal Ub inverted from the reverse monitor input terminal P4 as the reverse monitor signal Ms2.

Although not shown in detail in the circuit diagram of FIG. 1, in the actual circuit, the normal rotation output terminal P1 and the reverse rotation monitor input terminal P4 are adjacent to each other, and the reverse rotation output terminal P2 and the normal rotation monitor input terminal are provided. It is installed at a position adjacent to P3.

The CPU 21 uses the forward rotation monitor signal Ms1 and the reverse rotation monitor signal Ms2 to detect a short circuit of the pull-up resistors R3 and R4 connected to the signal lines L3 and L4, and controls the DC motor 13 in a first fail-safe process. I do. or,
The CPU 21 performs a second failsafe process of controlling the DC motor 13 by detecting a short circuit between the forward rotation output terminal P1 and the reverse rotation monitor input terminal P4 during the execution of the first failsafe process.

(First Fail-Safe Processing) Next, the CPU
The first fail-safe process executed by No. 21 according to the fail-safe program will be described.

The CPU 21 monitors whether the DC motor 13 is normally driven on the basis of the detection signal from the sensor group 11. For example, when the DC motor 13 is normally rotated, it is determined whether the normal rotation drive control signal Ua output from the normal rotation output terminal P1 is accurately output based on the normal rotation monitor signal Ms1. Based on the program, the normal rotation drive control signal Ua is compared with the normal rotation monitor signal Ms1. When the normal rotation drive control signal Ua is at the H level and the normal rotation monitor signal Ms1 is at the H level for a predetermined time, the CPU 21
It is determined that the pull-up resistor R3 connected to the signal line L3 is short-circuited with the plus terminal V +. More specifically, C
The PU 21 outputs the normal rotation monitor signal Ms1 for turning on the normal rotation FET elements Tr1 and Tr2 in spite of the fact that the normal rotation output terminal P1 is inactive in order to turn off the normal rotation FET elements Tr1 and Tr2. Determine that

On the other hand, the CPU 21 controls the reverse rotation monitor signal Ms.
Based on 2, it is determined whether the reverse drive control signal Ub output from the reverse output terminal P2 is accurately output.

The CPU 21 compares the reverse drive control signal Ub with the reverse monitor signal Ms based on the fail-safe program. Then, the reverse drive control signal Ub
Is at the H level and the reverse rotation monitor signal Ms2 remains at the H level for a predetermined time, the CPU 21 causes the signal line L
The pull-up resistor R4 connected to the
Judge that it is short-circuited with +. More specifically, the CPU 21
Indicates that the reverse rotation monitor signal Ms2 for turning on the reverse rotation FET elements Tr3, Tr4 is output even though the reverse rotation output terminal P2 is inactive for turning off the reverse rotation FET elements Tr3, Tr4. To judge.

Further, when the DC motor 13 is stopped at the neutral position or during steering, the forward drive control signal Ua and the forward monitor signal Ms1 are compared, and the reverse drive control signal Ub and the reverse monitor signal Ms2 are compared. Are compared with each other to determine whether they are normal, that is, whether the forward rotation monitor signal Ms1 and the reverse rotation monitor signal Ms2 are at the L level. If the forward rotation monitor signal Ms1 and the reverse rotation monitor signal Ms2 are at the H level, it is determined that one of the pull-up resistors R3 and R4 is short-circuited.

Pull-up resistor R3 or pull-up resistor R
When it is judged that 4 is short-circuited with the positive terminal V +, CP
U21 sets both the forward rotation output terminal P1 and the reverse rotation output terminal P2 to the L level. That is, both the signal lines L3 and L4 connected to the H bridge drive circuit 23 are set to the H level. The drive circuit 23 outputs a signal for turning off all the FET elements Tr1 to Tr4 to the gate terminals of the FET elements Tr1 to Tr4 when both the signal lines L3 and L4 become the H level, and stops the DC motor 13. Let

Therefore, when the steering is in the neutral position and the pull-up resistor R3 is short-circuited with the plus terminal V +, the DC motor 13 does not rotate normally or reversely. That is, when the steering wheel is in the neutral position, the direct-current motor 13 does not rotate normally or reversely to apply unnecessary steering torque to the steering wheel.

Further, the CPU 21 sets both the forward rotation and reverse rotation output terminals P1 and P2 to the L level and again sets the forward rotation and reverse rotation output terminals P1 and P2 to the H level again after a lapse of a predetermined time, to determine normal and abnormal again. to decide. At this time, the forward rotation monitor signal Ms1 and the reverse rotation monitor signal Ms2
If both are at the L level, it is determined that the recognition is incorrect and the normal operation is resumed.

Further, even in this re-judgment, the pull-up resistor R3
Alternatively, if it is determined that the pull-up resistor R4 is short-circuited with the plus terminal V +, there is no possibility of recovery, and both the forward rotation and reverse rotation output terminals P1 and P2 are again set to the L level, and then the power relay 17 is opened. Then, the power supply from the battery B to the DC motor 13 is stopped.

(Second Fail-Safe Processing) Next, the CPU
The second fail-safe process executed by the program 21 according to the fail-safe program will be described.

The CPU 21 holds both the forward rotation output terminal P1 and the reverse rotation output terminal P2 at the L level until the first fail-safe processing is executed and the normality is determined again. It is determined whether the forward rotation output terminal P1 and the reverse rotation monitor input terminal P4 are short-circuited. That is, the forward rotation output terminal P1 and the reverse rotation monitor input terminal P4 are adjacent to each other, and because they are adjacent to each other, there is a risk of a short circuit for some reason. The second fail-safe process is a process operation assuming the case where this short circuit occurs.

Now, the CPU 21 holds both the normal rotation output terminal P1 and the reverse rotation output terminal P1 at the L level and holds the signal lines L3 and L.
Both 4 are set to H level, and the drive circuit 23 stops the DC motor 13. At this time, the forward output terminal P
1 and the reverse rotation monitor input terminal P4 are short-circuited, the reverse rotation monitor signal M is generated by the L-level reverse rotation drive control signal Ub.
s2 goes from the H level to the L level. As a result, the signal line L4 becomes L level, and the drive circuit 23 causes the DC motor 13
Drive forward.

At this time, the reverse rotation monitor signal Ms2 becomes L level. Since the reverse rotation monitor signal Ms2 has to be at the H level but is at the L level, the CPU 21 determines that the forward rotation output terminal P1 and the reverse rotation monitor input terminal P4 are short-circuited.

When the CPU 21 determines that the forward rotation output terminal P1 and the reverse rotation monitor input terminal P4 are short-circuited, the CPU 21 changes the forward rotation output terminal P1 from L level to H level.
Set 4 to H level. As a result, the drive circuit 23 drives the DC motor 13 in reverse.

After a predetermined time, the CPU 21 changes the output terminal P1 for normal rotation from the H level to the L level, and the reverse rotation monitor signal Ms.
Set 2 to L level. Therefore, the signal line L4 becomes L level. As a result, the drive circuit 23 drives the DC motor 13 in the normal direction.

After that, the CPU 21 outputs the normal rotation output terminal P1.
This state is repeated at H level and L level in a predetermined cycle.
Therefore, since the levels of the signal lines L3 and L4 change as shown in FIG. 2, the direct-current motor 13 equally repeats forward rotation driving and reverse rotation driving in a predetermined cycle. As a result, the steering torques acting on the steering wheel in the opposite directions are cancelled. In other words, when the forward rotation output terminal P1 and the reverse rotation monitor input terminal P4 are short-circuited while the forward rotation and reverse rotation output terminals P1 and P2 are both held at the L level, one direction unintentionally occurs. No steering torque is applied to the.

If it is determined that the forward rotation output terminal P1 and the reverse rotation monitor input terminal P4 are not short-circuited, similarly, the reverse rotation output terminal P2 and the forward rotation monitor input terminal P3 are similarly.
Determine if and are shorted.

That is, the reverse rotation output terminal P2 and the forward rotation monitor input terminal P3 are adjacent to each other, and there is a risk of a short circuit for some reason. Now, the CPU 21 holds both the forward rotation output terminal P1 and the reverse rotation output terminal P1 at the L level and sets the signal lines L3 and L4 at the H level state to drive the drive circuit 23.
The DC motor 13 is stopped by. At this time, if the reverse rotation output terminal P2 and the normal rotation monitor input terminal P3 are short-circuited, the normal rotation drive control signal Ua at L level changes the normal rotation monitor signal Ms1 from H level to L level. As a result, the signal line L3 becomes L level, and the drive circuit 23 drives the DC motor 13 in reverse.

At this time, the normal rotation monitor signal Ms1 becomes L level. The CPU 21 determines that the reverse rotation output terminal P2 and the reverse rotation monitor input terminal P4 are short-circuited because the normal rotation monitor signal Ms1 has to be at the H level but is at the L level.

When the CPU 21 determines that the reverse rotation output terminal P2 and the forward rotation monitor input terminal P3 are short-circuited, the CPU 21 changes the reverse rotation output terminal P2 from L level to H level.
Set 3 to H level. As a result, the drive circuit 23 drives the DC motor 13 in the normal direction.

After a predetermined time, the CPU 21 changes the reverse rotation output terminal P2 from the H level to the L level, and the normal rotation monitor signal Ms.
Set 1 to L level. Therefore, the signal line L3 becomes L level. As a result, the drive circuit 23 drives the DC motor 13 in the normal direction.

Thereafter, the CPU 21 outputs the reverse rotation output terminal P2.
This state is repeated at H level and L level in a predetermined cycle. Therefore, since the levels of the signal lines L3 and L4 change as shown in FIG. 2, the direct-current motor 13 equally repeats forward rotation driving and reverse rotation driving in a predetermined cycle. As a result, the steering torques acting on the steering wheel in opposite directions are canceled out. That is, even when the reverse rotation output terminal P2 and the normal rotation monitor input terminal P3 are short-circuited while the forward rotation and reverse rotation output terminals P1 and P2 are both held at the L level, contrary to the intention, The steering torque is not applied in one direction.

During execution of the second fail-safe process, it is determined that the forward rotation output terminal P1 and the reverse rotation monitor input terminal P4 are short-circuited or the reverse rotation output terminal P2 and the forward rotation monitor input terminal P3 are short-circuited. Forward rotation monitor signal Ms
1 and the reverse rotation monitor signal Ms2 are monitored, and when the condition returns to normal, the normal operation is restored.

That is, when it is determined that the forward rotation output terminal P1 and the reverse rotation monitor input terminal P4 are short-circuited, the reverse rotation monitor signal Ms2 is synchronized with the change of the forward rotation drive control signal Ua.
When it is determined that only the reverse rotation output terminal P2 and the forward rotation monitor input terminal P3 are short-circuited, only the forward rotation monitor signal Ms1 changes in synchronization with the change of the reverse rotation drive control signal Ub. , The sensor group 11 is determined to have returned to normal
Restarts the assist control based on the detection signal from.

Further, even if a predetermined time elapses after it is first determined that the forward rotation output terminal P1 and the reverse rotation monitor input terminal P4 are short-circuited or the reverse rotation output terminal P2 and the forward rotation monitor input terminal P3 are short-circuited. If it does not return to normal, there is no chance of recovery and the power supply relay 17 is opened and the battery B
To stop the power supply to the DC motor 13.

As described above, this embodiment has the following effects. (1) In this embodiment, when the pull-up resistors R3 and R4 fail and are short-circuited to the plus terminal V +, the CPU 21
Both the forward and reverse output terminals P1 and P2 are set to L level, and the signal lines L3 and L4 are set to H level. And
By setting both signal lines L3 and L4 to H level,
The bridge drive circuit 23 stops the DC motor 13. Therefore, when the steering wheel is in the neutral position, the DC motor 13 does not reversely rotate to apply unnecessary steering torque to the steering wheel.

(2) In this embodiment, the CPU 21 keeps the normal rotation drive control signal Ua at the H level for a predetermined time.
When the normal rotation monitor signal Ms1 remains in the H level state, it is determined that the pull-up resistor R3 is short-circuited with the plus terminal V +. Therefore, it is possible to prevent the DC motor 13 from being stopped due to the forward rotation monitor signal Ms1 instantaneously becoming the H level due to the occurrence of instantaneous noise or the like which is not a short circuit failure.

(3) In this embodiment, the CPU 21 keeps the reverse drive control signal Ub at the H level for a predetermined time,
When the reverse rotation monitor signal Ms2 continues to be at the H level, it is determined that the pull-up resistor R4 is short-circuited with the plus terminal V +. Therefore, it is possible to prevent the DC motor 13 from being stopped due to the reverse rotation monitor signal Ms2 being momentarily at the H level due to the occurrence of momentary noise or the like which is not a short circuit failure.

(4) In this embodiment, the forward rotation output terminal P1 and the reverse rotation monitor input terminal P4 are controlled by controlling both the forward rotation and reverse rotation output terminals P1 and P2 at the L level to stop the DC motor 13. DC motor 1 when is short-circuited
The control of No. 3 is made to alternately repeat forward rotation and reverse rotation. Therefore, when the forward rotation output terminal P1 and the reverse rotation monitor input terminal P4 are short-circuited, the steering torques applied to the steering wheel acting in the forward and reverse directions cancel each other out. Steering torque is not applied in one direction.

The embodiment of the present invention may be modified as follows. In the above embodiment, the CPU 21 determines that the normal rotation drive control signal Ua is at the H level and the normal rotation monitor signal Ms1 is at the H level.
When the level state continued for a predetermined time, it was determined that the pull-up resistor R3 was short-circuited. The CPU 21 may immediately determine that the short circuit has occurred and execute the first fail-safe process.

In the above embodiment, the CPU 21 short-circuits the pull-up resistor R4 when the reverse drive control signal Ub is at H level and the reverse monitor signal Ms2 is at H level for a predetermined time. I decided. this,
The CPU 21 may immediately determine that there is a short circuit and execute the first fail-safe process.

In the above embodiment, the CPU 21 outputs the forward rotation drive control signal Ua and the reverse rotation drive control signal Ub to the H bridge drive circuit 23 via the inversion circuit 22. The inverting circuit 22 may be omitted, and the CPU 21 may be configured to directly output the forward rotation drive control signal Ua and the reverse rotation drive control signal Ub to the H bridge drive circuit 23.

In the above embodiment, the normal rotation output terminal P1 is used.
And the reverse rotation monitor input terminal P4 are short-circuited, the control of the DC motor 13 is alternately repeated forward and reverse. In addition to this, when the reverse rotation output terminal P2 and the forward rotation monitor input terminal P3 are short-circuited for some reason,
DC motor 1 so that forward rotation and reverse rotation are equally repeated alternately.
3 may be controlled and implemented.

[0072]

According to the first to fifth aspects of the present invention, it is possible to reliably prevent the deterioration of the steering feeling with respect to the occurrence of a short circuit failure.

In addition, according to the second aspect of the invention, it is possible to prevent the DC motor 13 from being stopped due to the occurrence of momentary noise or the like which is not a short circuit failure. In addition, according to the invention of claim 3, when the output terminal of the forward rotation control signal and the input terminal of the reverse rotation monitor signal are short-circuited, it is prevented that the steering torque is applied in one direction against the intention. can do.

In addition, according to the invention of claim 4, when the output terminal for the reverse rotation control signal and the input terminal for the forward rotation monitor signal are short-circuited, the steering torque is applied in one direction against the intention. Can be prevented.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of an electric power steering controller.

FIG. 2 is a forward rotation output terminal P1 and a reverse rotation monitor input terminal P.
4 is a time chart of signals on signal lines L3 and L4 when 4 and 4 are short-circuited.

[Explanation of symbols]

10 ... Electric power steering control device, 13 ...
Electric motor, 15 ... H-type bridge circuit as drive circuit, 21 ... CPU as control circuit, Tr1,
Tr2 ... Switching element for forward rotation, Tr3, Tr4
... switching element for reverse rotation, L3 ... signal line for forward rotation, L4 ... signal line for reverse rotation, Ua ... drive control signal for forward rotation as a forward rotation control signal, Ub ... as reverse rotation control signal Reverse rotation drive control signal, Ms1 ... forward rotation monitor signal, Ms2 ... reverse rotation monitor signal, P1, P2 ...
Reverse rotation monitor input terminals as output terminals, P3, P4 ... Input terminals.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kiyotaka Iwata             1-1 Asahi-cho, Kariya city, Aichi             Machine Co., Ltd. (72) Inventor Akira Ito             1-1 Asahi-cho, Kariya city, Aichi             Machine Co., Ltd. (72) Inventor Yutaka Mori             1-1 Asahi-cho, Kariya city, Aichi             Machine Co., Ltd. F term (reference) 3D033 CA03 CA11 CA13 CA16 CA21                 5H571 AA03 BB07 CC02 DD00 EE02                       FF09 HA09 HB00 HD01 JJ03                       LL44 LL45

Claims (5)

[Claims] 1. An electric motor for imparting steering torque to a steering wheel, a forward rotation switching element for driving the electric motor in the forward direction, a reverse rotation switching element for driving the electric motor in the reverse direction, and the electric motor. A forward rotation control signal for driving the electric motor in the forward direction and a reverse rotation control signal for driving the electric motor in the reverse rotation direction, and the forward rotation control signal is input via a forward rotation signal line to the forward direction. Controls the diversion switching element and inputs the reverse rotation control signal through the reverse rotation signal line to control the reverse rotation switching element. When the forward rotation control signal and the reverse rotation control signal are simultaneously input, the forward rotation and reverse rotation switching is performed. An electric power steering control device comprising a drive circuit for turning off both elements, wherein the control circuit transmits to the forward rotation signal line. Input signal as a forward rotation monitor signal, and the signal transmitted to the reverse rotation signal line is input as a reverse rotation monitor signal, and a forward rotation control signal or a reverse rotation monitor signal different from the forward rotation control signal or the reverse rotation control signal is input. An electric power steering control device characterized in that, when output, a forward rotation control signal and a reverse rotation control signal are simultaneously output to a drive circuit. 2. The electric power steering control device according to claim 1, wherein the control circuit continuously outputs a normal rotation monitor signal or a reverse rotation monitor signal different from the normal rotation control signal or the reverse rotation control signal for a predetermined time. An electric power steering control device characterized in that, when output, a forward rotation control signal and a reverse rotation control signal are simultaneously output to a drive circuit. 3. The electric power steering control device according to claim 1, wherein the control circuit outputs the normal rotation control signal and the reverse rotation control signal to the drive circuit at the same time. The electric power steering control device is characterized in that the reverse rotation control signal is output at a predetermined cycle when the output terminal for outputting the reverse rotation monitor signal is short-circuited with the input terminal for inputting the reverse rotation monitor signal. 4. The electric power steering control device according to claim 1, wherein the control circuit outputs the forward rotation control signal and the reverse rotation control signal to the drive circuit at the same time. Electric power steering control characterized in that when the output terminal for outputting the reverse rotation control signal is short-circuited with the input terminal for inputting the forward rotation monitor signal, the forward rotation control signal is output at a predetermined cycle. apparatus. 5. The electric power steering control device according to claim 1, wherein the electric motor is a DC motor, and the H-type bridge circuit includes the forward rotation switching element and the reverse rotation switching element. An electric power steering control device characterized in that the electric power steering control device is connected to.