JPH01244975A - Electric power steering device - Google Patents

Abstract

PURPOSE:To prevent wrong judgement and delay in response at the time of a failure by setting a failure judging time to time according to a vehicle condition in a system where an electric current applied to and electric motor is stopped when abnormality in a required device of the above device is detected extending over a failure judging time. CONSTITUTION:The above device is constructed so that in a control device 10, steering force assisting amount is computed according to detection values of a torque sensor 8 and a car velocity sensor 9 to control the drive of an electric motor 1 and apply steering assisting force to a steering system. Further, a failure of each portion of the power steering device is judged, and a relay contact of a fail relay circuit 7 is turned off to stop the feed of power to the electric motor 1. In this case, the above failure judgement is such that when abnormality in a required device is continuously detected during a designated failure judging time, it is judged to be the occurrence of failure. The failure judging time is set according to the vehicle condition. For example, when an alternator generates electricity, the failure judging time is set to be comparatively shorter than the during non-generation of electricity.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an electric power steering device.

Conventional electric power steering devices generally detect malfunctions in each device and supply power to an electric motor to assist the steering force, in order to prevent malfunctions due to failures in each device of the electric power steering device. It has a fail-safe function that stops the operation. In the failure detection of each device, in order to prevent false detection due to noise or the like, when an abnormality in each device is continuously detected for a predetermined failure determination period, it is determined that the device has failed. Conventionally, the failure determination time is always set to a constant value.

Problems to be Solved by the Invention Conventionally, the failure determination time is fixed regardless of the vehicle condition, so that depending on the vehicle condition, a certain device may be erroneously determined to be at fault when it is not, or a failure may occur. However, there is a problem in that it takes too much time to determine a failure, resulting in a delay in response.

For example, if we want to monitor fluctuations in the drive voltage of an electric motor that assists steering force to determine if there is a failure in the electric motor's drive circuit. An abnormality is detected even if no failure has occurred in the drive circuit. Therefore, if the motor drive circuit failure determination time is set short, a failure may be erroneously determined during cranking even if no failure has occurred. In order to prevent this erroneous determination, if the failure determination time is set long, failure determination in vehicle states other than cranking will be delayed.

Also, considering the case of determining failure of the torque sensor,
During cranking, the internal circuit of the sensor no longer operates normally due to a drop in supply voltage due to cranking, so an abnormality is detected even if the sensor is not malfunctioning. Therefore, the same inconvenience arises as in the failure determination of the motor drive circuit.

Considering the case of determining the failure of the Kura Sochi, which is installed between the electric motor to assist the steering force and the steering system, when the vehicle speed exceeds a certain level, the influence of the moment of inertia of the electric motor on the steering system is considered. However, if the clutch is engaged due to a clutch failure when the vehicle speed is above a certain level, the steering system will suddenly change for the driver, and the driver may be forced to disengage the clutch. It can be felt as a shock and is extremely dangerous. In order to prevent such a risk from occurring, it is preferable to shorten the clutch failure determination time as much as possible when the vehicle speed is above a certain level.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electric power steering device that can appropriately determine a failure depending on the vehicle condition.

Means for Solving the Problems The electric power steering device according to the present invention includes a means for detecting whether or not an abnormality has occurred in each of the necessary devices of the electric power steering device, and a means for detecting whether or not an abnormality has occurred in each of the necessary devices of the electric power steering device, In an electric power steering device that monitors a vehicle condition, the electric power steering device is equipped with a means for determining that the device has failed when an abnormality is detected, and stopping power supply to an electric motor for assisting steering force.
The present invention is characterized in that it includes means for setting a failure determination time to a time corresponding to a vehicle condition.

Vehicle conditions such as operating driving (speed) conditions and power generation conditions of the generator are monitored, and failure determination times for required equipment of the power steering system are automatically set to times that correspond to the vehicle conditions.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows the overall schematic configuration of an electric power steering device. This device includes an electric motor (1) for assisting steering force, a motor drive circuit (2), a clutch (3) provided between the electric motor (1) and the steering system, and a clutch drive circuit. (4), motor drive circuit (2) and main type lf7. (battery) (3), a key switch (6) and a fail relay circuit (7), a torque sensor (8) that detects the input torque of the steering shaft, and a vehicle speed sensor (9) that detects the vehicle speed. , a control device (10) that controls the motor (1) and the clutch (3) based on the detected torque of the l-lux sensor (8), the detected speed of the vehicle speed sensor (9), etc., and also controls the fail relay circuit (7). It is equipped with

Although not shown, the motor drive circuit (2), torque sensor (8), vehicle speed sensor (9), clutch drive circuit (4)
Abnormality detection circuits for detecting abnormalities in various parts of the power steering apparatus are provided, and detection signals from each abnormality detection circuit are sent to the control device (10).

In addition, a power generation state detection signal is provided to determine whether the alternator is in a power generation state or a non-power generation state.
A power generation state detection signal from this circuit is sent to the control device (10).

The motor (1) is equipped with a reducer and a clutch (3) at an appropriate location such as the output shaft of the steering shaft or the steering gear.
) etc.

The torque sensor (8) includes, for example, a potentiometer that detects twisting of a torsion bar provided between the input shaft and the output shaft of the steering shaft.

The control device (10) is equipped with a microcomputer, and controls the steering force assistance amount of the motor (1) based on the torque detected by the torque sensor (8), the speed detected by the vehicle speed sensor (9), etc. In addition to performing quantity control processing, failure monitoring processing such as determining failure of each part of the power steering device and turning off the relay contact of the fail relay circuit (6) is performed.

FIGS. 2 to 4 show processing by the control device (10). The processing by the control device (10) includes main processing;
There is interrupt processing.

FIG. 2 shows the main processing procedure. First, initialization processing is performed (step 21). In this initialization process,
In the subsequent failure monitoring process, various registers used as counters are cleared, etc. After the initialization processing, the predetermined main processing is executed by determining whether the contents of the main processing execution interval regulation register, whose contents are incremented by 1 in the timer processing of step 31 of the interrupt processing described later, have reached a predetermined value. It is determined whether the execution interval has elapsed (time-up) (step 22).

If the predetermined main processing execution interval has elapsed, fault monitoring processing (step 23) and processing such as vehicle speed calculation based on the detection signal of the vehicle speed sensor (9) (step 24) are performed. After this, a watchdog pulse used to detect program runaway is output (step 25),
Return to step 22.

In step 22, if the predetermined main processing execution interval has not elapsed, the process proceeds to step 25 without performing steps 23 and 24, and a watchdog pulse is output.

FIG. 3 shows the procedure for interrupt processing.

This interrupt processing is executed at regular time intervals based on the interrupt signal. In this process, first, timer processing is performed (step 31). In this timer processing, the contents of the main processing execution interval regulation register are +1.
be done.

Next, the input torque of the steering shaft detected by the torque sensor (8) is read (step 3).
2). Further, the steering direction is determined based on the input signal from the torque sensor (8). Then, the target value of the steering force assistance amount is calculated based on the read input torque and the latest vehicle speed determined in step 24 of the main process.
Step 33).

Thereafter, a steering force assist amount control signal representing the calculated target value and a rotation direction control signal corresponding to the steering direction are output to the motor drive circuit (2) (step 34), and this interrupt processing ends.

In step 34, the steering force assist amount control signal and the rotational direction control signal are sent to the motor drive circuit (2), so that the motor (1) has a rotational torque of a magnitude corresponding to the steering force assist amount control signal.・The rotation direction is driven in a direction according to the rotation direction control signal.

FIG. 4 shows details of the failure monitoring process of the main process.

For convenience of explanation, only the processes based on failures of the motor drive voltage of the motor drive circuit (2), the torque sensor (8), and the clutch drive circuit (4) among the various parts of the power steering device are shown here, and the processes based on other devices are shown here. is omitted.

The failure monitoring process includes a motor failure monitoring process (step 41) for a failure in the motor drive circuit (2), a torque sensor failure monitoring process (step 42), and a clutch drive circuit (4).
) Clutch failure monitoring processing (step 43)
), failure determination time setting process based on power generation status (step 4
4) and a failure determination time setting process (step 45) based on the driving condition are sequentially performed.

In the motor failure monitoring process (step 41), first, the motor drive voltage is monitored, and based on the detection signal from the motor abnormality detection circuit that detects the motor drive voltage, an abnormality is detected in the motor drive voltage of the motor drive circuit (2). It is determined whether or not this has occurred (step 51). When it is determined that no abnormality has occurred in the motor drive voltage, the motor failure determination register (content NA) is used as a counter to measure the abnormality detection time of the motor drive voltage.
is cleared (step 55), and the process moves to step 42, the torque sensor failure monitoring process.

When it is determined in step 51 that an abnormality has occurred in the motor drive voltage, the content NA of the motor failure determination register is incremented by 1 (step 52). Then, the updated contents NA of the register are compared with the failure determination reference value TA representing the motor failure determination time (step 53).
).

The initial value of this reference value TA is set as follows in the initialization process of step 21 of the main process. That is, in the initialization process, the power generation state of the alternator is checked, and if it is not generating power, it is set to a relatively large value TA (H), and if it is generating power, it is set to a relatively small value TA (L). . In the initial state of the vehicle, it is assumed that the alternator (4) is not generating power, and the initial value of the reference value TA may be set to TA (H) in the initialization process.

If the content NA of the register is equal to or greater than the reference value TA, it is determined that the abnormality detection has continued for the failure determination time or longer, that is, it is determined that a failure such as a disconnection has occurred in the motor drive circuit (2), and the fail relay circuit (7 ) is performed (step 54).
).

When the register content NA is smaller than the reference value TA,
The process proceeds to step 42, torque sensor failure monitoring processing, without performing failsafe processing.

In the torque sensor failure monitoring process (step 42), first, it is determined whether or not an abnormality has occurred in the torque sensor (8) based on a detection signal from the torque sensor abnormality detection circuit (step 61). Torque sensor (8)
When it is determined that no abnormality has occurred in the torque sensor (8), the torque sensor failure determination register (8), which is used as a counter to measure the abnormality detection time of the torque sensor (8)
content NB) is cleared (step 65), and step 4
The process moves on to step 3, clutch failure monitoring processing.

When it is determined in step 61 that an abnormality has occurred in the torque sensor (8), the content NB of the torque sensor failure determination register is incremented by 1 (step 62).

Then, the updated register content NB is compared with a failure determination reference value TB representing the torque sensor failure determination time (step 63).

The initial value of this reference value TB is set as follows in the initialization process of step 21 of the main process. That is, in the initialization process, the power generation state of the alternator is checked, and if it is not generating power, it is set to a relatively large value TB (H), and if it is generating power, it is set to a relatively small value TB (L). . In the initial state of the vehicle, the alternator may be considered to be in a non-generating state, and the initial value of the reference value TB may be set to TB (H) in the initialization process.

If the contents NB of the register are equal to or greater than the reference value TB, it is determined that a failure has occurred in the torque sensor (8), and fail-safe processing is performed (step 64). When the content NB of the register is smaller than the reference value TB, the process moves to clutch failure monitoring processing in step 43 without performing fail-safe processing.

In the clutch failure monitoring process (step 43), first, based on the detection signal from the clutch abnormality detection circuit,
It is determined whether an abnormality has occurred in the clutch drive circuit (4) (step 71). Clutch drive circuit (4)
When it is determined that no abnormality has occurred in the clutch drive circuit (4), the clutch failure determination register (4) is used as a counter to measure the abnormality detection time of the clutch drive circuit (4).
content NC) is cleared (step 75), and step 4
The process moves on to the failure determination time setting process based on the power generation state in step 4.

When it is determined in step 71 that an abnormality has occurred in the clutch drive circuit (4), the content NC of the clutch failure determination register is incremented by 1 (step 72).

Then, the updated register contents NC are compared with a failure determination reference value TC representing the clutch failure determination time (
Step 73).

The initial value of this reference value TC is set as follows in the initialization process of step 21 of the main process. That is, in the initialization process, the vehicle speed is lower than the predetermined speed (driving state determination speed) at which the clutch (3) is automatically disengaged (the traveling state in this case is referred to as a low speed traveling state), or the vehicle speed is lower than the driving state determining speed. It is determined whether the vehicle is in the above condition (the traveling state in this case is referred to as a high-speed traveling state).

Then, when the driving state is a low-speed driving state, a relatively large value TC(H) is set, and when the driving state is a high-speed driving state, a relatively small value TC(L) is set. In the initial state of the vehicle, it may be assumed that the vehicle is running at a low speed, and the initial value of the reference value TC may be set to TC(H) in the initialization process.

If the contents NC of the register are equal to or greater than the reference value TC, it is determined that a failure has occurred in the clutch drive circuit (4), and fail-safe processing is performed (step 74). When the contents NC of the register are smaller than the reference value TC, the process proceeds to Step 44, a failure determination time setting process based on the power generation state, without performing the failsafe process.

Failure judgment time setting process based on power generation status (step 44)
In step 81, it is first determined whether the alternator is in a power generation state or a non-power generation state based on a detection signal from the alternator power generation state detection circuit.
). When it is determined that the alternator is in a non-generating state, a register (contents NDH) for measuring power generation detection time, which is used as a counter to time the detection time of a power generation state, is cleared (step 82). .

Then, the content NDL of the register for measuring the non-power generation detection time, which is used as a counter for measuring the detection time of the non-power generation state, is incremented by 1 (step 83). Next, in order to confirm the reliability of the determination result in step 81,
The content NDL of the register for measuring the power generation non-detection time is compared with a power generation state determination reference value TD representing a predetermined power generation state determination time (step 84).

If the content NDL of the register for measuring the non-power generation detection time is equal to or greater than the reference value TD for power generation state determination, it is confirmed that there is no power generation, and the failure determination standard representing the motor failure determination time used in motor failure monitoring processing is confirmed. The value TA is set to a predetermined relatively large value TA (H), and the six failure determination reference value TB representing the torque sensor failure determination time used in the torque sensor failure monitoring process is set to a predetermined relatively large value TA (H). The value TB (H) is set (step 85). As a result, when the alternator is in a non-generating state such as during cranking, the motor failure determination time and the torque sensor failure determination time are set to relatively long times.

In the step 84, when the content NDL of the register for measuring the non-detection time of power generation is smaller than the reference value TD for determining the power generation state, the setting of the reference values TA and TB is not changed in the step 85, and the running state in the step 45 is determined. The process moves on to failure determination time setting processing.

When it is determined in step 81 that the alternator is in the power generation state, the register (contents NDL) for measuring the non-power generation detection time is cleared (step 86). Then, the content NDH of the register for measuring power generation detection time is +
(step 87). Next, the content NDH of the power generation detection time register is compared with a power generation state determination reference value TD representing a predetermined power generation state determination time (step 88).

If the content NDH of the generation detection time register is equal to or greater than the failure determination reference value TD, the failure determination reference value TA representing the motor failure determination time is set to a predetermined relatively small value TA (L). At the same time, a failure determination reference value TB representing the torque sensor failure determination time is set to a predetermined relatively small value TB (L) (step 89). As a result, when the alternator is in the power generation state, the motor failure determination time and the torque sensor failure determination time are set to relatively short times.

In step 88, the content NDH of the register for measuring power generation detection time is 7! for power generation state determination! If it is smaller than the standard value TD, the setting of the reference values TA and TB is not changed in step 89, and the process moves to step 45, which is a failure determination time setting process based on the driving condition.

Failure determination time setting process based on driving conditions (step 45)
In step 91, it is determined whether the vehicle speed is lower than a predetermined speed at which the clutch (3) is automatically disengaged, or whether the vehicle speed is equal to or higher than the driving state determination speed. When the running state is a low-speed running state, a high-speed running detection time register (content NEH) used as a counter for counting the high-speed running state detection time is cleared (step 92).

Then, the content NEL of the low-speed running detection time register used as a counter for counting the low-speed running state detection time is incremented by 1 (step 93). next,
In order to confirm the reliability of the judgment result in step 91, the content NEL of the register for measuring low-speed driving detection time is compared with a reference value TE for driving state judgment representing a predetermined driving state □ judgment time. (Step 94).

If the content NEL of the register for measuring low-speed running detection time is equal to or greater than the reference value TE for running state determination, it is confirmed that the running state is low-speed, and the failure determination criterion representing the clutch failure determination time used in clutch failure monitoring processing is determined. The value TC is set to a predetermined relatively large value TC(H) (
Step 95). As a result, when the vehicle is running at a low speed, the clutch failure determination time is set to a relatively long time.

In step 94, when the content NFL of the low-speed driving detection time register is smaller than the driving state determination reference value TE, the failure monitoring process ends without changing the setting of the reference value TC in step 95; The process moves to step 24, a vehicle speed calculation process.

When it is determined in step 91 that the running state is a high-speed running state, the low-speed running detection time register (content NEL) is cleared (step 96).

And the contents of the register for high-speed driving detection time measurement NEW
is updated to a value incremented by 1 (step 97). next,
The content NEH of the high-speed driving detection time register is compared with a driving state determination reference value TE representing a predetermined driving state determination time (step 99).

If the content NEH of the register for high-speed driving detection time measurement is equal to or greater than the driving state determination reference value TE, the failure determination reference value TC representing the clutch failure determination time is set to a predetermined relatively small value TC (L). (Step 99).

As a result, when the running state is a high-speed running state, the clutch failure determination time is set to a relatively short time.

In step 98, if the content NEH of the high-speed driving detection time register is smaller than the reference value TE for driving state determination, the failure monitoring process ends without changing the setting of the base value TC in step 99. , the process moves to step 24, the vehicle speed calculation process.

Effects of the Invention The electric power steering device according to the present invention is equipped with means for monitoring the vehicle condition and setting the failure determination time to a time corresponding to the vehicle condition.
Appropriate failure judgment can be made. Therefore, as before,
Depending on the condition of the vehicle, a malfunction may be incorrectly determined even though it is not a malfunction, or even when a malfunction occurs, it takes too long to determine the malfunction.
Delays in response can be avoided.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is an electrical block diagram showing the electrical configuration of an electric power steering device; FIG. 2 is a flow chart showing the main processing procedure by the control device; and FIG. FIG. 4 is a flowchart showing the procedure of interrupt processing by the device. FIG. 4 is a flowchart showing the procedure of fault monitoring processing executed in the main processing. (1)...Motor, (5)...Main power supply, (7)...
-Fail relay circuit, (10)...control device. Patent applicant: Koyo Seiko Co., Ltd. Agent
Person Einosuke Kishimoto (4 others) μ 4th

Claims (1)

[Claims] Regarding the required equipment for electric power steering equipment,
Means for detecting whether or not an abnormality has occurred, and an electric motor for determining that the device has failed and assisting the steering force when an abnormality is continuously detected for a predetermined failure determination period. An electric power steering device equipped with a means for stopping power supply to the vehicle, characterized in that the electric power steering device is equipped with a means for monitoring a vehicle condition and setting a failure determination time to a time corresponding to the vehicle condition. Device.