JPH0714112Y2 - Runaway prevention device for electric power steering - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a runaway prevention device for an electric power steering system.

(Prior Art) Conventionally, as a means for preventing the steering system from running out of control due to an abnormality in the steering torque detector, the main contactor is tripped to prevent current from flowing to the motor to prevent runaway. It was

(Problems to be solved by the invention) However, in the above-mentioned means, a time delay of sufficient msec to several tens of msec occurs during the trip after the OFF command is output to the excitation circuit of the main contactor, and the time An abnormal current flows through the motor during the delay.

To prevent this, trip the main contactor and at the same time force the element controlling the current flowing through the motor.
A circuit that turns off can be considered.

However, in the above circuit, when the element is forcibly turned off during steering operation, a considerable kickback from the road surface is fielded back to the steering wheel, and in the worst case, the driver breaks the arm bones. There was a danger and there was a safety problem.

(Means for Solving the Problem) A runaway prevention device for an electric power steering device of the present invention (hereinafter referred to as a device of the present invention) includes a first main switching element Tr1, a second main switching element Tr2, a third main switching element Tr3, and a third main switching element Tr3. 4 Main switching element Tr4
Connected to the bridge, the first main switching element Tr1
And the connection point of the third main switching device Tr3 and the second
A main circuit 10 in which an electric motor 5 is connected to the connection point of the main switching element Tr2 and the fourth main switching element Tr4, a steering torque detector 6 for converting the steering torque force of the steering system into an electric signal, and the main circuit described above. According to both detection signals of the current detector 8 flowing in 10, the first main switching element Tr1, the second main switching element
A control circuit 7 for controlling conduction of the Tr2, the third main switching element Tr3, and the fourth main switching element Tr4 is provided, and the control circuit 7 detects an abnormality in the control circuit 7 and the steering torque detector 6 A forced lock circuit 7D that controls the conduction of only the third main switching element Tr3 and the fourth main switching element Tr4 by the output from the circuit 7B.
An electric power steering runaway prevention device comprising: It is configured to solve the above problems.

(Embodiment) An embodiment of the device of the present invention will be described with reference to FIGS.

Reference numeral 1 is a battery, 2a is a main contactor, 2b is a main contactor exciting coil, and Tr1, Tr2, Tr3, Tr4 are main switching elements for controlling the direction and amount of current flowing in the electric motor 5, and four main switching elements, that is, 1 main switching element Tr1, 2nd main switching element Tr2, 3rd main switching element Tr3 and 4th main switching element Tr4 are flywheel diodes, and are connected in parallel to each of main switching elements Tr1, Tr2, Tr3, Tr4. There is. Reference numeral 5 denotes a first main switching element Tr1 and a third main switching element Tr3 that generate auxiliary torque.
Connection point and the second main switching element Tr2 and the fourth
The electric motor connected to the connection point of the main switching element Tr4, the first, second, third, fourth main switching element
A main circuit 10 is formed by the bridge connection of Tr1, Tr2, Tr3, Tr4 and the electric motor 5. 6 is a steering torque detector, 7 is a control circuit 7 for controlling ON / OFF of the main switching elements Tr1, Tr2, Tr3, Tr4 according to the output of the steering torque detector 6,
The control circuit 7 compares the conduction ratio control circuit 7A with a previously stored normal range value and the current detection signal or the steering torque force detection amount signal from the current detector 8 to determine whether the normal range value is normal or normal. If it is smaller or larger than the range value, it is determined to be abnormal, and when it is determined to be abnormal, an abnormal signal is generated, and the abnormal signal is output to the contactor drive circuit 7E and the forced lock circuit 7D.
Error detection circuit 7B that outputs to the main switching element Tr
It is composed of a drive circuit 7C for turning ON / OFF 1, Tr2, Tr3, Tr4, a compulsory lock circuit 7D for preventing the steering system from running out of control when an abnormality occurs in the control circuit 7 and the steering torque detector 6. .

The operation of the device of the present invention will be described below. The steering torque detector 6 detects a necessary amount of steering torque and direction, and converts the steering torque and direction into an electric signal and outputs the electric signal.
Next, the control circuit 7 turns on / off the main switching elements Tr1, Tr2, Tr3, Tr4 with the signal taken from the steering torque detector 6.
To control.

For example, when the steering torque detector 6 outputs an output to the control circuit 7 when the auxiliary torque for clockwise rotation is required, the control circuit 7
Turns off one of the main switching elements Tr2 and Tr3, and gives the other main switching elements Tr1 and Tr4 a duty factor command commensurate with the auxiliary torque required. Also in the case of counterclockwise rotation, one of the main switching elements Tr1 and Tr4 is
The FF is performed and the necessary conduction ratio command is given to the other main switching elements Tr2 and Tr3. Here, if the steering torque detector 6
If an abnormality occurs in the main contactor 2a, the main contactor 2a is tripped and
Tr4 is forcibly turned off and the other main switching element
By forcibly turning on Tr3 and Tr4, the terminals of the electric motor 5 can be short-circuited, the electric motor 5 can be dynamically braked, and kickback can be prevented.

(Effects) Since the device of the present invention has the above-described configuration and operation, it is possible to prevent the kickback by locking the electric motor for power generation. Therefore, even if an abnormality occurs in the control circuit or the steering torque detector, the driver can be safely operated without causing any danger.

[Brief description of drawings]

FIG. 1 shows an electric main circuit diagram including the device of the present invention, and FIG. 2 shows a circuit diagram of the device of the present invention. 1 …… Battery 2a …… Main contactor 2b …… Main contactor Excitation coil Tr1, Tr2, Tr3, Tr4 …… Main switching element 4 …… Flywheel diode 5 …… Electric motor 6 …… Steering torque detector 7 …… Control circuit 8 ... Current detector

Claims (1)

[Scope of utility model registration request] 1. A first main switching element Tr1, a second main switching element Tr2, and a third main switching element Tr.
The 3rd and 4th main switching elements Tr4 are connected to a bridge, and the motor is connected to the connection point of the 1st main switching element Tr1 and the 3rd main switching element Tr3 and the connection point of the 2nd main switching element Tr2 and the 4th main switching element Tr4. According to both detection signals of the main circuit 10 connecting the five, the steering torque detector 6 for converting the steering torque force of the steering system into an electric signal, and the current detector 8 flowing in the main circuit 10, The control circuit 7 includes a control circuit 7 for controlling conduction of the first main switching element Tr1, the second main switching element Tr2, the third main switching element Tr3, and the fourth main switching element Tr4. The control circuit 7 includes a control circuit 7 and a steering torque detector 6 An abnormality detection circuit 7B that detects that an abnormality has occurred in the third main switch element Tr3 and the fourth Electric power steering runaway prevention device formed by including the forced locking circuit 7D for conduction control only in the switching element Tr4.