JP2864695B2 - Electric power steering device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric power steering apparatus, and more particularly, to an electric power steering apparatus that detects and protects a failure of a steering motor.

[Conventional technology]

2. Description of the Related Art Conventionally, as an electric power steering apparatus capable of detecting and protecting a failure of a steering motor, a current detection value of an electric motor that assists a steering force of a steering handle is set to a predetermined first threshold for a predetermined time or more. Then, when exceeding the first, it is determined that the motor is short-circuited.
Detecting means for determining that the motor has been disconnected when a current detection value of the motor is smaller than a second threshold set lower than the first threshold and a control signal for driving the motor is given. And a current opening / closing means for stopping the power supply to the electric motor when it is determined as described above.

[Problems to be solved by the invention]

In the above-mentioned conventional electric power steering apparatus, the value of the current flowing through the steering motor is detected, and it is determined whether or not there is a failure based on the detected value.

However, the steering motor current is irregular,
Unstable and difficult to detect outliers,
There is a problem that it is difficult to set a level value at which a failure detection determination should be made.

[Object of the invention]

SUMMARY OF THE INVENTION The present invention is to solve such a problem of the prior art, and it is possible to reliably detect and protect short-circuit and disconnection failures of a steering motor in an electric power steering device, and to improve the performance of the steering motor. An object of the present invention is to provide an electric power steering device capable of performing high-temperature protection without lowering the steering feeling and extending the life of the motor by protecting the steering motor at high temperature.

[Means for solving the problem]

The present invention relates to an electric power steering device for driving a steering motor (9) when detecting a steering torque in a steering shaft (2) to apply an auxiliary steering force to the steering shaft (2). And detecting the temperature of the steering motor (9), and generating a short circuit in the steering motor (9) when the supply power of the detected temperature of the motor temperature sensor (11) and a rise value per time exceed a first set value. When the temperature rise value does not reach the second set value, the occurrence of disconnection in the steering motor (9) is determined. At these times, the driving of the steering motor (9) is stopped and a fault is displayed. Is performed.

The present invention also relates to an electric power steering device for driving a steering motor (9) to apply an auxiliary steering force to the steering shaft (2) when detecting a steering torque in the steering shaft (2). To detect the temperature at the steering motor (9), and to provide the motor environment temperature sensor (13) to detect the air temperature near the steering motor (9) and to supply the detected temperature at the motor temperature sensor (11). The occurrence of a short circuit in the steering motor (9) is determined when the power and the rise per time exceed the first set value, and the disconnection in the steering motor (9) is performed when the temperature rise does not reach the second set value. When the occurrence is determined, the driving of the steering motor (9) is stopped, a failure is displayed, and When the temperature detected by the motor temperature sensor (11) exceeds the third set value, a correction value of the motor current is obtained from the detected temperature and the temperature detected by the motor environment temperature sensor (13), and the steering is performed in accordance with the correction value. The motor (9) is driven.

This aims to achieve the above-mentioned object.

[Action]

The temperature of the steering motor is detected, and when the detected power supply and the rise per time exceed the first set value, it is determined that the steering motor is short-circuited, and the temperature rise reaches the second set value. If not, the occurrence of disconnection in the steering motor is determined. At the time of these determinations, the driving of the steering motor is stopped and the display of the failure is performed, so that the failure detection and protection of short-circuit and disconnection of the steering motor in the electric power steering device can be reliably performed.

In addition, the temperature of the steering motor is detected, and the air temperature near the steering motor is detected. When the supply power of the motor temperature and the rise value per time exceed a first set value, it is determined that a short circuit has occurred in the steering motor. When the temperature rise value does not reach the second set value, the occurrence of disconnection in the steering motor is determined, and in these determinations, the driving of the steering motor is stopped, a failure is displayed, and the detection by the steering motor is performed. When the temperature exceeds the third set value, a correction value of the motor current is obtained from the detected temperature and the detected air temperature in the vicinity of the steering motor, and the steering motor is driven according to the correction value. Detection and protection of short-circuit and disconnection of steering motor Ukoto it is, it is possible to perform high-temperature protection of the steering motor without reducing the steering feeling, and can be extended motor life due to the high temperature protection of the steering motor.

Embodiment FIG. 1 shows a configuration of an embodiment of the present invention.

In FIG. 1, when a steering handle 1 is operated, the operation force (steering force) is changed to a steering shaft 2.
Is transmitted to the rack and pinion device 3 via the rack and pinion device 3 to turn the front wheel 4.

When detecting the direction and magnitude of the operation force of the steering shaft 2, the torque sensor 5 performs filtering and analog-to-digital (A / D) conversion through the interface circuit 6 and inputs the result to the microcomputer 7. Microcomputer 7
Controls the motor drive circuit 8 according to the input of the vehicle speed information when there is an input from the interface circuit 6, whereby a current is supplied from the motor drive circuit 8 to the steering motor 9 so that the steering motor 9 It rotates at a predetermined speed in a predetermined direction. The rotation of the steering motor 9 is transmitted to the steering shaft 2 via the reduction gear 10 to generate an auxiliary operation force.

The motor temperature sensor 11 detects the temperature of the steering motor 9, performs filtering and A / D conversion via the interface circuit 12, and inputs the result to the microcomputer 7. The motor temperature sensor 11 may be installed outside (outer surface) of the steering motor 9 or may be installed inside the steering motor 9.

The detection value of the motor temperature sensor 1 is subjected to arithmetic processing in the microcomputer 7 according to a predetermined program, and the steering motor 9 is controlled according to the result of the arithmetic processing.

The present invention relates to an electric power steering device which applies an auxiliary steering force to a steering shaft 2 by driving a steering motor 9 when a steering torque in the steering shaft 2 is detected. The temperature in the motor 9 is detected.

Then, when the supply power of the detected temperature of the motor temperature sensor 11 and the rise value per time exceed the first set value, the occurrence of a short circuit in the steering motor 9 is determined, and the temperature rise value reaches the second set value. If not, determine the occurrence of disconnection in the steering motor 9 and
When the occurrence of short circuit or disconnection is determined in this way,
The driving of the steering motor 9 is stopped and a failure is displayed.

FIG. 2 shows a failure detection subroutine in the embodiment of FIG. 1, and detects and determines a failure of the steering motor 9 and the motor drive circuit 8 when the electric power steering device is driven. is there.

. Is the drive output to the steering motor turned on?

If it is not turned on, it will not be possible to judge the failure.
Fly to return.

. Input the detection value T _M of the motor temperature sensor.

When the drive output to the steering motor is on, the temperature of the steering motor is measured. The time at that time is t ₁ [sec], and the motor temperature is T _M.

. Is the drive output to the steering motor kept on?

 If it has not been turned on, it jumps to return.

. Input the detection value T _M + ΔT _M of the motor temperature sensor.

Measure the temperature of the steering motor. The time at that time is t ₁ + Δt ₁ second, and the motor temperature is T _M + ΔT _M.

. Calculating the variation [Delta] T _M of the detected value of the motor temperature sensor.

P is the electric power supplied to the steering motor during Δt for _one second. The electric power P is a steering motor supply voltage.
The microcomputer 7 calculates and estimates from V _M , the duty ratio γ _M , the steering motor resistance _{RM, and the} like. The estimation formula in this case is based on the following formula (3).

However, in practice, equation (3) is not satisfied due to various factors.
Create a map of V _M , duty ratio γ _M and power P,
Used for estimating the motor supply power P.

From the equations (1) and (2), the temperature fluctuation ΔT _MP is obtained. The temperature fluctuation ΔT _MP is not a simple motor temperature fluctuation but a motor power fluctuation per supply power and time.

. Is the temperature fluctuation ΔT _MP equal to or greater than the constant value T _m1 ?

The value of T _{m1 is} a value for determining whether the motor is short-circuited. When the motor is short-circuited, an overcurrent flows through the motor, and the value of the temperature fluctuation ΔT _MP becomes larger than the value of T _m1 .

FIG. 3 shows a change in motor temperature during a short circuit.

From FIG. 3, the value of the calculated temperature fluctuation ΔT _MP is ΔT _MP
> It is determined that T _m1, hence the predetermined time t _2, the motor drive output signal is turned off.

. Is the temperature fluctuation ΔT _MP less than or equal to the fixed value T _m2 ?

The value of T _{m2 is} a value for determining whether the motor is disconnected. When the wire is disconnected, no current flows to the steering motor, and the value of the temperature fluctuation ΔT _MP becomes smaller than the value of T _m2 .

FIG. 4 shows a change in motor temperature at the time of disconnection.

From FIG. 4, the value of the calculated temperature fluctuation ΔT _MP is ΔT _MP
<It is determined that T _{m @ 2,} thus the predetermined time t _2, the motor drive output signal is turned off.

. It is determined that the motor is short-circuited.

In the case of YES in the step, it is determined that the steering motor is short-circuited.

. It is determined that the motor is disconnected.

In the case of YES in the step, it is determined that the steering motor is disconnected.

. Stop the motor drive output of the microcomputer.

If it is determined in step or that a short-circuit or disconnection has occurred, the motor drive output is turned off. This third view of the foregoing, as shown in FIG. 4, an operation performed t ₂ time.

. Displays the failure judgment result.

In the or step, the driver or the like is notified of the result determined to be short-circuited or disconnected.

The above-described failure detection subroutine may be executed only once immediately after the motor drive output is turned on after the engine is turned on, or may be executed at a time when the motor drive output is turned on. It is assumed that the main routine has been programmed.

FIG. 5 shows a change in the motor temperature in a normal state.

Further, by incorporating the motor temperature sensor into the system, it is possible to protect the motor other than short-circuiting and disconnection of the steering motor.

FIG. 6 shows the configuration of another embodiment of the present invention.

6, the same components as those in the embodiment of FIG. 1 are denoted by the same reference numerals, and 13 is a motor environment temperature sensor for detecting an air temperature near the steering motor.

The detection value of the motor environment temperature sensor 13 is input to the interface circuit 12 together with the detection value of the motor temperature sensor 11, subjected to filtering and A / D conversion, and then input to the microcomputer 7.

The present invention relates to an electric power steering device that applies an auxiliary steering force to the steering shaft 2 by driving a steering motor 9 when detecting a steering torque in the steering shaft 2.
A motor temperature sensor 11 is provided to detect the temperature of the steering motor 9 and to provide a motor environment temperature sensor.
13 is provided to detect the air temperature near the steering motor 9.

Then, when the supply power of the detected temperature in the motor temperature sensor 11 and the rise value per time exceed the first set value, it is determined that a short circuit has occurred in the steering motor 9,
When the temperature rise value does not reach the second set value, the occurrence of disconnection in the steering motor 9 is determined, the driving of the steering motor 9 is stopped, and a failure is displayed.

Further, the temperature detected by the motor temperature sensor 11 is the third temperature.
When the set value is exceeded, a correction value of the motor current is obtained from the detected temperature and the detected temperature of the motor environment temperature sensor 13,
The steering motor 9 is driven according to this correction value.

The motor failure detection processing in the embodiment of FIG.
This is performed according to a subroutine shown in FIG. The conditions in this case are the same as in the embodiment shown in FIG.

FIG. 7 shows a subroutine for steering motor protection in the embodiment of FIG.

: Motor temperature sensor value T _M , motor environment temperature sensor value T _Ma
Enter

The temperature of the steering motor and the air temperature near the steering motor are measured.

: Is the motor temperature sensor value T _M greater than the constant value T _m3 ?

It is determined whether the steering motor current can be driven without correction.

: Controls the motor drive correction output of the microcomputer.

The current control value of the conventional electric power steering device is corrected.

That is, by lowering the steering motor current value by a certain rate, it is possible to prevent the motor temperature from increasing and to prevent the steering feeling from deteriorating.

FIG. 8 is a diagram showing control contents of a motor drive correction output.

As shown in FIG. 8, the target motor temperature T _m4 (the target motor temperature T _m4 is set to be equal to or slightly lower than the aforementioned temperature value T _m3 ) and the motor temperature T _M A motor current correction value _ku is calculated from the deviation e (= T _m4 −T _M ).

An example of this calculation is I was raised, but the value of k _u is between 0 and 1, which is a value determined by the value of T _M and T _Ma.

Using the correction value k _U for correcting the motor current, 'to, u = k _u u' conventional electric power steering apparatus at the calculated input current value u by obtained by performing the calculation as a current value u And control the steering motor.

In FIG. 8, a portion surrounded by a dashed line indicates the content of control for the conventional electric power steering device.

The current correction control (motor drive correction output control of the microcomputer) in such a motor protection routine stops the correction when _ku = 1.

As described above, in the embodiment shown in FIG. 6, the motor temperature and the air temperature near (around) the motor are always detected, and the output of the motor current value is reduced and corrected (0 ≦ _ku ≦ ₁ ). I have.

〔The invention's effect〕

As described above, according to the present invention, in the electric power steering apparatus, by detecting and controlling the motor temperature, it is possible to reliably detect and protect the short-circuit and disconnection failure of the steering motor and to protect the steering motor. ,
By detecting and controlling the motor environment temperature in addition to the motor temperature, it is possible to detect and protect the short-circuit and disconnection failure of the steering motor, and to protect the high-temperature of the steering motor without lowering the steering feeling.
In addition, the high temperature protection of the steering motor can extend the life of the motor.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention, FIG. 2 is a diagram showing a subroutine of failure detection in the embodiment of FIG. 1, FIG. 3 is a diagram showing a change in motor temperature at the time of short circuit, 4th
FIG. 5 is a diagram showing a change in motor temperature at the time of disconnection, FIG. 5 is a diagram showing a change in motor temperature in a normal state, FIG. 6 is a diagram showing the configuration of another embodiment of the present invention, and FIG. FIG. 6 is a diagram showing a subroutine for steering motor protection in the embodiment of FIG. 6, and FIG. 8 is a diagram showing control contents of a motor drive output. 2 ... steering shaft, 9 ... steering motor, 11 ... motor temperature sensor, 13 ... motor environment temperature sensor.

Claims (2)

(57) [Claims] 1. An electric power steering apparatus for driving a steering motor to apply an auxiliary steering force to a steering shaft when detecting a steering torque on the steering shaft, comprising: a motor temperature sensor for detecting a temperature of the steering motor. When the supply power of the detected temperature in the motor temperature sensor and the rise value per time exceed a first set value, it is determined that a short circuit has occurred in the steering motor, and when the temperature rise value does not reach the second set value. An electric power steering apparatus, wherein the occurrence of disconnection in the steering motor is determined, and when the occurrence of the short circuit or disconnection is determined, the driving of the steering motor is stopped and a failure is displayed. 2. An electric power steering apparatus for driving a steering motor to apply an auxiliary steering force to the steering shaft when detecting a steering torque on the steering shaft, comprising: a motor temperature sensor for detecting a temperature of the steering motor; A motor environment temperature sensor for detecting an air temperature in the vicinity of the steering motor, wherein when the supply power of the detected temperature of the motor temperature sensor and a rise value per time exceed a first set value, occurrence of a short circuit in the steering motor is detected. When the temperature rise value does not reach the second set value, it is determined that a disconnection has occurred in the steering motor, the driving of the steering motor is stopped, a failure is displayed, and the detection by the motor temperature sensor is performed. Temperature exceeds the third set value When obtains the correction value of the motor current from the detection temperature and the detected temperature of the motor environment temperature sensor, the electric power steering apparatus characterized by driving the steering motor in accordance with the correction value.