JPH01223072A - Electric power steering device - Google Patents

Abstract

PURPOSE:To correctly judge the abnormality of a torque sensor by comparing the change rate of the output signal of the torque sensor detecting the steering torque and the threshold value set according to the car speed to judge the abnormality of the torque sensor. CONSTITUTION:The steering input sent to a sleeve 30 is transmitted to an output shaft 21 via a rod (torsion bar) 7, and wheels are steered by a steering mechanism containing a pinion 22 and a rack 11. In this case, the torsion quantity of the rod 7 twisted in response to the magnitude of the inputted steering torque is detected by a torque sensor 40, and motor 8 is driven by a control means according to the detected steering torque, and the power is transmitted to the output shaft 21 via a reduction mechanism (gears 23 and 25) or the like. In the above control means, the change rate of the output signal of the torque sensor 40 is determined, and this change rate is compared with the threshold value set according to the car speed to judge the abnormality of the torque sensor 40.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electric power steering device, and in particular, it is capable of detecting an abnormality in a torque sensor that detects a steering torque externally applied to a steering wheel. Electric power steering device (related).

[Prior Art] As a technique related to this type of electric power steering device, there is a technique for an electric power steering device disclosed in Japanese Patent Application Laid-Open No. 12459/1983.

The technology described in the above publication controls the current to the motor according to the torsional torque of the steering shirt I~, and uses the rotation of the motor to provide power assist in the steering direction. In an electric power steering device that gradually reduces power assist in the steering direction as the vehicle speed increases, the electric power steering device includes a vehicle speed determination unit that generates a signal when a vehicle speed signal from a vehicle speed sensor exceeds a predetermined value, and a torsional torque sensor. and a torsional torque discriminator that generates a signal when the torsional torque signal from the vehicle exceeds a predetermined value, and when a signal is generated from both the vehicle speed discriminator and the torsional torque discriminator. It generates a signal that activates the system shut-off mechanism and warning device.

Therefore, when it detects that an abnormally large torsional torque signal is generated during driving due to a failure of the torsional torque sensor, etc., it activates the system cutoff mechanism of the electric power steering device to switch to manual steering, and also activates the warning device. It is possible to give a warning to the crew about the occurrence of an abnormal situation.

[Problems to be Solved by the Invention] However, in the above-mentioned electric power steering device, there is a vehicle speed determination section that generates a signal when the vehicle speed signal from the vehicle speed sensor exceeds a predetermined value, and a torsional torque from the torsional torque sensor. Since it has a torsional torque determination section that generates a signal when the signal exceeds a predetermined value, there is a problem in that it is impossible to determine whether the torque sensor is abnormal when the vehicle speed is below a predetermined value. In addition, as shown in the torque abnormality characteristic diagram for determining abnormality of the torque sensor in Fig. 11, the torque signal suddenly changes from rightward torque to leftward torque or from leftward torque to rightward torque, and then the torsional torque sensor There has been a problem in that even if Tatsumi regular torsional torque signals below a predetermined threshold are continuously generated, they cannot be detected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an electric power steering device that can determine an abnormality based on the state of change in the output from a torque sensor.

[Means for Solving the Problems] - The electric power steering device according to the present invention includes a motor that is drive-controlled to replenish the steering torque in accordance with the output of a torque sensor that detects the steering torque applied to the steering wheel. and slowing down the rotation of the motor,
The rotation is transmitted to the steering shaft. At this time, the rate of change detection means detects the rate of change of the output signal of the torque sensor, and the output of the threshold setting means changes the threshold of the rate of change of the output signal of the torque sensor according to the output of the vehicle speed sensor. The comparison is made using a discrimination means and the abnormality is determined.

[Operation] In the present invention, a torque sensor detects the steering torque applied to the steering wheel, and the motor is drive-controlled so as to supplement the steering torque according to the output of the torque sensor, thereby controlling the rotation of the motor. By decelerating the steering wheel with a speed reduction mechanism and transmitting the rotation to the steering shaft, it is possible to supplement the steering torque that rotates the steering wheel using the motor. At the same time, the change rate of the output signal of the torque sensor at this time is detected by the change rate detection means, the output of the vehicle speed sensor is detected by the threshold 1a setting means, and the torque sensor is detected according to the output of the respective vehicle speed sensor. The threshold value of the rate of change of the output signal is changed. Then, the abnormality determining means compares the output of the rate of change detection means with the output of the threshold value setting means, and determines whether the torque sensor is abnormal based on the magnitude of the rate of change of the output of the torque sensor. This abnormality in the torque sensor releases the crutch mechanism interposed between the motor and the speed reduction mechanism, allowing manual steering of the steering device.

[Example] Fig. 1 is a circuit configuration diagram of an electronic control means of an electric power steering device according to an embodiment of the present invention, Fig. 2 is a perspective view showing an outline of the electric power steering device according to the above embodiment, and Fig. 3 This figure is an enlarged sectional view of an auxiliary power supply means having a motor for auxiliary steering force in the embodiment of FIG. 2. 4 is a front view showing the outer surface of the sleeve 30 shown in FIG.
The figure is a sectional view taken along section line XX shown in FIG.

In FIGS. 2 and 3, a first steering shaft 2 to which a steering wheel 1 is fixed is connected to a second steering shaft 5 through a first universal joint 4. As shown in FIG. A rod 7 is connected to the second steering shaft 5 through a second universal joint 6. This rod 7 has a pinion gear 22 (
The output shaft 21 (see FIG. 3) has an output shaft 21 (see FIG. 3).

The pinion gear 22 meshes with a rack 11 fixed to the tie rod 10. The tie rod 10 is the wheel 12
The steering knuckle arm 16 is connected to the steering knuckle arm 16 of the steering knuckle arm 16.

A shock absorber 13 is connected to the axle of the wheel 12, and a suspension upper support 14 of the shock absorber 13 is connected to the vehicle body. Coil spring 15 is suspension upper support 14
It is used for vibration damping between the axle and the axle.

Further, 18 is a lower suspension arm, and 19 is a stabilizer bar.

The upper end of the rod 7 is connected to the second steering shaft 5 via a second universal joint 6. A sleeve 30 is fixed to the lower end of the upper end of the rod 7 and is pivotally supported by a reduction mechanism case 31 by a pin 29.

Further, the rod 7 passes through the sleeve 30 and is inserted into the output shaft 21, and the output shaft 21 is fixed to the lower end thereof by a pin 20. The output shaft 21 is pivotally supported by a reduction mechanism case 24, and a pinion gear 22 formed at its lower end meshes with the rack 11.

Therefore, when the steering wheel 1 rotates, the output shaft 21 is rotationally driven via the first steering shaft 2, the first universal joint 4, the second steering shaft 5, the second universal joint 6, and the rod 7. The rack 11 that meshes with the pinion gear 22 formed on the output shaft 21 is driven in a direction perpendicular to the paper plane of FIG. 3 (the direction in which the tie rod 10 extends in FIG. 2), and the direction of the wheel 12 is changed. . In addition, the output shaft 21
A ring gear 23 is formed at the upper end of the hollow, and meshes with an intermediate gear 25 pivotally supported by a case 24. Another intermediate gear 26, which is coaxial with and integral with the intermediate gear 25, meshes with the input gear 27. The input gear 27 is fixed to an output rotating shaft 28 of the clutch mechanism CL, which is interposed between the output shaft of the motor 8 and the not-shown output shaft. In a state where the clutch device 4g0L is connected, when the motor 8 is energized, the output shaft 21 rotates from the input gear 27 through the intermediate gear 26 and from the intermediate gear 25 through the ring gear 23.
The rack 11 that meshes with the pinion gear 22 formed in the rack 11 is driven in a direction perpendicular to the paper plane of FIG. 2, and the direction of the axle 12 is changed.

In this way, the direction of the wheel is changed by either rotation of the steering wheel 1 or energization of the motor 8 in the forward or reverse direction. However, when the clutch mechanism CL is released, the output shaft (not shown) of the motor 8 and the clutch mechanism CL
Since no energy is transmitted between the steering wheel and the output rotating shaft 2B, the direction of the wheel is changed by externally applied rotation of the steering wheel 1.

A wheel 32 is rotatably mounted on the sleeve 30. That is, the sleeve 30 passes through the wheel 32. A round bottom groove 33 is formed on the outer surface of the sleeve 30 and is oblique to the central axis of the sleeve 30, and a ball 34 is fitted into the round bottom groove 33. The ball 34 is supported by the wheel 32 and has a fitting groove 35.
The upper end of the pin 36 fixed to the upper end of the output shaft 21 is located at. This pin 36 restricts rotation of the wheel 32.

Therefore, when the rod 7 rotates, the sleeve 30 and the output shaft 21 rotate, but since the sleeve 30 is fixed to the upper end of the rod 7 and the output shaft 21 is fixed to the lower end of the rod 7, the load on the output shaft 21 is large. and the rod 7 is twisted. The rotation angle between the sleeve 30 and the output shaft 21 is shifted by the maximum amount of this twist, and the wheel 32 is rotated in the same direction as the output shaft 21 via the pin 36, so the rotation angle shift is as follows. This results in a difference in rotation angle between the sleeve 30 and the wheel 32.

Further, in FIG. 5, the sleeve 30 and the output shaft 21 are formed into a planar shape at this portion, and each has opposing two-hand surface portions 23a.

This bimanual surface portion 23a limits the rotational angle deviation between the sleeve 30 and the output shaft 21 that exceeds a predetermined value.

That is, within the range limited by the two-hand surface portion 23a, the sleeve 3 is moved relative to the wheel 32 by an amount corresponding to the rotation angle deviation.
Since the round bottom groove 33 of the sleeve 30 is oblique to the central axis of the sleeve 30, the ball 34 is pushed upward or downward by the round bottom groove 33, and the ball 34 is pushed upward or downward. The supporting wheels 32 move upwardly or downwardly. Therefore, steering wheel 1
If the steering i・lux applied to is less than the predetermined value,
The steering torque corresponds to the twist of the rod 7, and the wheel 32 moves to an upper or lower position in accordance with the amount of twist. That is, displacement of the wheel 32 in an upward or downward direction corresponds to a steering torque that is less than or equal to the predetermined value.

The wheel 32 has an annular groove 37 in which a ball 39 is engaged. The ball 39 is an elastic plate 3
It is supported at one end of 8. The round end of the elastic plate 38 is fixed. The elastic plate 3B is provided with a torque sensor 4 consisting of a total of two strain detection elements, one on each of the front and back surfaces.
0 is joined. These two strain detection elements are connected in series, and the potential at the connection point is output as a torque detection signal.

Therefore, when the rod 7 is twisted in response to the steering torque applied to the steering wheel 1 and the wheel 32 is moved upward or upward from the zero position, the groove 37 and the ball 39 are twisted.
The elastic plate 38 bends upward or out of alignment, and the torque sensor 40 detects the displacement m of the wheel 32 (the amount of displacement from the zero steering torque position), that is, the applied steering torque which is the torsion of the rod 7. Generates an electrical signal indicating the As mentioned above, the twisting of the rod 7 causes the output shaft 21 and the sleeve 3 to
0, the torque sensor 40 is linear when the steering torque is applied within the predetermined range, and saturated when the steering torque is applied beyond the predetermined range. The output will be

The electronic control means for driving and controlling the electric power steering device configured as described above is shown in FIG.

The microcomputer CPU, which embodies the change rate detection means, threshold value setting means, and abnormality determination means of this embodiment and constitutes the control circuit, is composed of a 1-chip microcomputer, and includes ROM, RAM, timer, and counter as is well known. etc. are built-in. Its power is supplied from a constant voltage circuit CC. The input of the microcomputer CPLJ receives an intrusion force whose waveform is shaped by a waveform shaping circuit WS, which is the pulse number output of a vehicle speed sensor SP consisting of a permanent magnet MG that rotates according to the vehicle speed, a reed switch LS, and a resistor R6.

Resistance r1 of the strain detection element. r2 and fixed resistance r3. r
The output of the four-bit torque sensor 40 is output from the amplifier AMP1.
The signal is inputted to the microcombiner CPtJ via a control compensation circuit PID that compensates for proportional, integral, and differential control constants, and an A/D conversion circuit AD having a built-in multiplexer. Further, the output of the torque sensor 40 consisting of the strain detection element is inputted via the sensor abnormality detection circuit SA.

Further, the drive current of the motor 8 is detected as a voltage drop across a current detection resistor R5, and is input to the A/D conversion circuit AD via an amplifier AMP2.

On the other hand, the output of the microcomputer CPLJ is connected to the relay RY via the relay drive circuit DR3. Therefore, when the relay output of the microcomputer CPU is 1, the relay RY is energized and its contact ry is closed. Further, when the power is OFF, the relay RY can be de-energized and its contact ry can be opened. Therefore, if relay RY is de-energized, its contact ry is opened,
The rotation of the motor 8 can be stopped regardless of the left signal, the right signal, and the PWM signal (ratio of the output of the duty ratio signal), which will be described later, and fail-safe support can be provided.

Further, the output of the microcomputer CPJJ is connected to the coil of the clutch mechanism CL via the clutch drive circuit DR5, and when the relay output of the microcomputer CPU is "1", the clutch mechanism CL is connected to " It is in a released state when it is OPI.

The transistor Q1 and the base resistor R1 constitute a switching circuit, and the left signal of the microcomputer CPU is
1' is the transistor Q1 via the drive circuit DPI.
is turned on, and the left signal "O+t" turns off the transistor Q1.

Similarly, the transistor Q2 and the base resistor R2 constitute a switching circuit, and the right signal 1'' of the microcomputer CPtJ turns on the transistor Q2 via the drive circuit DR1, and the right signal O'' turns off the transistor Q2. becomes.

Transistor Q3 and base resistor R3 constitute a switching circuit, and P
The transistor Q3 is turned on via the drive circuit DR2 at 1' of the WM signal, and the transistor Q3 is turned off by the output of the PWM signal. Similarly, the transistor Q4 and the base resistor R4 constitute a switching circuit, and the PWM signal of the microcomputer CPLI is
1'' turns on the transistor Q4 via the drive circuit DR2, and the PWM signal “Otp turns off the transistor Q4.

Therefore, the motor 8 is connected to the transistor Q1 when the left signal is "
When turned on by 1'° or turned on by "1" of the right signal of transistor Q2, it rotates left or right depending on the PWM signal of the microcomputer CPU.

Note that the diodes D1 to D4 are for a flywheel that prevents the transistors Q1 to Q4 from being destroyed.

Further, the output of the microcomputer CPU is input to the LED drive circuit DR4, which lights up the light emitting diode LED by repeatedly blinking when the torque sensor 40 is abnormal.

The microcomputer CPLJ of the electric power steering apparatus of this embodiment configured as described above is program-controlled as follows.

FIG. 6 is a flowchart of the main program for controlling the electric power steering device of the above embodiment;
The figure is a flowchart of the "abnormality determination processing routine 1" that controls the electric power steering apparatus of the above embodiment, and FIG. 8 shows the "abnormality determination processing routine 2" that controls the electric power steering apparatus of the above embodiment. The flowchart is ten.

First, this program is started by turning on the ignition switch IG, and in step S1, the RAM and timer built in the microcomputer CPU are cleared, and each output port is initialized.

In step S2, the output of the torque sensor 40 is input to the amplifier AMP.
1. Control compensation circuit PID that compensates for proportional, integral, and differential control constants, and A/D conversion circuit AD that has a built-in multiplexer.
The output of the torque sensor 40 at that time is stored in the memory Mn-1. In step S3, the clutch mechanism CL@ is engaged, and in step S4, the relay RY is energized via the relay drive circuit DR3, and its contact ry is closed.

In step S5, vehicle speed data is input from the vehicle speed sensor SP, and the r vehicle speed input processing routine J for calculating the current vehicle speed is called, and the vehicle speed is calculated and stored in the memory Msp. In step S6, the output of the torque sensor 40 is input, and the output of the torque sensor 40 at that time is stored in the memory Mn.

In step S7, □ "different-commercial processing routine 1" is called, and in step 38, "abnormality determination processing routine 2j" is called.
is called, and an abnormality in the torque sensor 40 is determined based on the output of the torque sensor 4'O. - Also, in step S9, the "f duty ratio output calculation processing routine" is called, and the output of the torque sensor 40 stored in the memory Mn is used to generate the PW" output signal, that is, the duty ratio signal, which is supplied to the motor 8. The output of the torque sensor 4 stored in the memory Mn is then called at step 810, and the ``left/right direction determination processing routine'' is calculated.
The rotation direction of the motor 8 is determined using the output of 0, and the current direction of the duty ratio signal to be supplied to the motor 8 is determined.

"Duty ratio output calculation processing routine" in step S9 and "left/right direction determination processing routine" in step 810
The duty ratio and leftward or rightward rotation direction, which are the PWM signals determined in , are output. And step 3
To obtain the time of differential time Δ1− in 12, T m5e
The progress of step c is determined, and the routine from step S5 to step 312 is repeated.

The above-mentioned "vehicle speed input processing routine", "duty ratio output calculation processing routine", and "left/right direction discrimination processing routine" are program controls well known in power assist control, so their explanations will be omitted.

Next, the "abnormality determination processing routine 1" in step S7 is performed.
This will be explained using the flowchart in FIG. 7 and the characteristic diagram of the change rate threshold value of this embodiment in FIG.

First, from the vehicle speed stored in the memory Msp in step 321, a threshold value setting means for determining a threshold value for the rate of change of the output signal of the torque sensor 40 according to the output of the vehicle speed sensor SP at that time selects a rate of change threshold value 6th/ds. Determine. That is, in the ROM of the microcomputer CPtJ,
The characteristic that the change rate threshold value 6th/ds decreases as the vehicle speed increases, as shown in FIG. 9, is stored in the memory map. This memory may be stored as an approximate expression or as a numerical value. Step S2
In step 2, the rate of change dTH/ds of the output signal of the torque sensor 40 for each differential time ΔT is subtracted from the 1 shift stored in the memory Mn-1 by the 1 shift stored in the memory Mn, and the absolute value of It is determined by calculating the itch. Step 32
3, the value stored in memory 1vln is stored in memory Mn-1. In step S24, the rate of change threshold dth/ds corresponding to the vehicle speed and in step S5 to step 31 are determined.
The rate of change dTH per differential time ΔT, which is the time to complete 2.
/ds and determines the change rate threshold d according to the vehicle speed.
Differential time from jh/dS, rate of change for each JT dTl-i/
When ds is small, it is not determined that there is an abnormality and this routine is exited.

In step S24, when the rate of change dTH/ds of the output signal of the torque sensor 40 for each differential time ΔT is equal to or greater than the rate of change threshold dth/ds according to the vehicle speed, it is determined that the torque sensor +) is abnormal. Then, in step 825, it is determined whether T1 time has elapsed in order to gradually decrease the duty ratio, and when it is determined that 11 hours have elapsed, the duty ratio is reduced to 1% in step 826.
It is determined in step 327 whether the reduced duty ratio has become zero, and if it has not become zero, a duty ratio signal and a leftward or rightward rotation direction are output in step 328. When it is determined that the duty ratio reduced in step 327 has become zero, the duty ratio signal and the leftward or rightward rotation direction output are cut off in step S29, contact ry of relay RY is opened, and clutch mechanism CL is closed. As a release, switch to manual steering. Then, in step 530, the light emitting diode LED is blinked to indicate the occurrence of an abnormality, and this is displayed to the driver.

That is, when it is determined that there is an abnormality, the duty ratio is gradually decreased to zero according to the routine from step 825 to step 82B so as not to give a sudden torque change to the driver holding the steering wheel 1. do.

In addition, the "abnormality determination processing routine 2" in step S8 is
This will be explained using FIGS. 8 and 10.

First, in step 331, the torque sensor 4 of the memory Mn stored in the memory 1Vln-1 in step 323
0 output value and memory MSE calculated in step S5)
Using the characteristic diagram of the abnormal output value of the electric power steering device of the present embodiment shown in FIG. In step S32, it is determined whether the
Similarly, it is determined whether the value in the memory Mn-1 is equal to or greater than the right rotation abnormality threshold LHAX, which is an abnormal value of the left rotation torque.

The output value of the torque sensor 40 is the right rotation abnormality threshold RHA.
When the value between X and left rotation abnormality @L) is less than IAX, exit from this routine. That is, due to the characteristic that the abnormal output value decreases as the vehicle speed increases, the threshold value of the abnormal output of the torque sensor 40 is changed according to the speed, and it is determined whether the abnormal output value is within the normal threshold value.

In step S31 or step S32, the torque sensor υ4 is
When the output value of 0 is above the right rotation abnormality threshold RHAX or below the left rotation abnormality threshold LMAX, it is determined that the torque sensor is working, and in step 333, it is determined that the T1 time has elapsed in order to gradually decrease the duty ratio. Then, when it is determined that the T1 time has elapsed, the duty ratio is reduced by 1% in step S34, and it is determined in step S35 whether the reduced duty ratio has become zero, and if it has not become zero, the duty ratio signal and Outputs left or right rotation direction. When it is determined that the duty ratio reduced in step 335 has become zero, the duty ratio signal and the leftward or rightward rotation direction output are cut off in step S37, contact ry of relay RY is opened, and clutch l1lICL is released. As a result, you can switch to manual steering. Then, in step 338, the light emitting diode LED is blinked to indicate the occurrence of an abnormality, and this is displayed to the driver.

In this way, similarly to the former case, when it is determined that the vehicle is in constant use, the duty ratio is gradually decreased by the routine from step 333 to step 337 so as not to give a sudden torque change to the driver holding the steering wheel 1. to make the duty ratio zero.

As described above, the electric power steering device of this embodiment includes a torque sensor 40 that detects the steering torque applied to the steering wheel 1, and a torque sensor 40 that detects the steering torque applied to the steering wheel 1.
A motor 8 that controls the drive of the motor 8 to supplement the steering torque according to the output of the motor 8, a speed reduction mechanism 9 that slows down the rotation of the motor 8 and transmits the rotation to the steering shaft, and a speed reduction mechanism 9 between the motor 8 and the speed reduction mechanism 9. An interposed clutch mechanism OL, a change rate detection means for detecting a change rate of the output signal of the torque sensor 40 constituted by a microcomputer CPU, and a change in the output signal of the torque sensor 40 according to the output of the vehicle speed sensor SP. It consists of a threshold value setting means for changing the rate threshold value, and an abnormality determining means for comparing the output of the rate of change detection means and the output of the threshold value setting means.

Note that the rate of change detection means for detecting the rate of change of the output signal of the torque sensor 40 detects the rate of change dlH/ds of the output signal of the torque sensor 40 every time the main routine is repeatedly performed.
and store it in memory Mn-1, and from the value stored in memory M
It is obtained by subtracting a stored value from n and calculating its absolute value. Further, the same value setting means for changing the threshold value of the rate of change of the output signal of the torque sensor +J 40 according to the output of the vehicle speed sensor SP sets the rate of change threshold value as the vehicle speed increases, which is stored in the ROM of the microcomputer CPtJ. A memory map with a characteristic that dth/ds decreases is used. The abnormality determining means compares the output of the rate of change detection means and the output of the threshold (a setting means),
Change rate threshold dth/ds by microcomputer CPU
This is done by comparing the rate of change and the rate of change dTH/ds.

Therefore, the torque sensor 40 detects the steering torque applied to the steering wheel 1, and the motor 8 is controlled to rotate so as to supplement the steering torque according to the output of the torque sensor 40. By reducing the speed with the deceleration mechanism 9 and transmitting the rotation to the steering shaft, the driver can supplement the steering torque for rotating the steering wheel 1 using the motor 8. At the same time, the change rate of the output signal of the torque sensor 40 at this time is detected by the change rate detection means, and the output of the vehicle speed sensor SP is detected by the threshold value setting means, and the The threshold value of the rate of change of the output signal of the torque sensor 40 is changed. Then, the abnormality determining means compares the output of the rate of change detection means with the output of the threshold setting means, and determines whether the torque sensor 40 is abnormal based on the magnitude of the rate of change in the output of the torque sensor 40. When an abnormality occurs in the torque sensor 40, the clutch mechanism CL interposed between the motor 8 and the deceleration mechanism 9 is released, the light emitting diode LED is blinked to indicate the occurrence of an abnormality, and the steering device is switched to manual steering. can do.

Therefore, if the torque sensor 40 is abnormal, manual steering can be performed by releasing the clutch mechanism CL interposed between the motor 8 and the speed reduction mechanism 9, and unnecessary drive torque is applied to the steering wheel 1. I can't get caught.

[Effects of the Invention] As described above, the electric power steering device of the present invention includes a torque sensor that detects the steering torque applied to the steering wheel, and a system that replenishes the steering torque according to the output of the torque sensor. The torque sensor includes a motor to drive and control, a deceleration mechanism that decelerates the rotation of the motor and transmits the rotation to the steering shaft, and a clutch mechanism interposed between the motor and the deceleration mechanism. An abnormality determining means compares the output of a rate of change detection means for detecting the rate of change of the output signal and the output of a dark value setting means for changing a threshold value of the rate of change of the output signal of the torque sensor according to the output of the vehicle speed sensor. It is something to do.

Therefore, the output of the rate of change detection means for detecting the rate of change of the output signal of the torque sensor, and the output of the dark value setting means for changing the threshold of the rate of change of the output signal of the torque sensor 1 according to the output of the vehicle speed sensor. By comparing with abnormality determination means,
An abnormality in the torque sensor υ can be determined based on the size of the change rate of the output of the torque sensor, and an abnormal output of the torque sensor can be accurately determined. The clutch mechanism can be released and the steering device can be operated manually.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of an electronic control means of an electric power steering device according to an embodiment of the present invention, FIG. 2 is a perspective view showing an overview of the electric power steering device of the above embodiment, and FIG. FIG. 4 is a front view showing the outer surface of the sleeve shown in FIG. 3, and FIG. 5 is a cutting line shown in FIG. 3. A sectional view taken along line X-X, FIG. 6 is a flowchart of the main program for controlling the electric power steering device according to the embodiment of the present invention, and FIG. 7 is a flowchart for controlling the electric power steering device shown in FIG. The flowchart of "Abnormality determination processing routine 1", FIG.
9 is a characteristic diagram of the rate of change liI value of the electric power steering device according to the embodiment of the present invention, and FIG. 10 is a flowchart of the abnormality determination processing routine 2 of the electric power steering device according to the embodiment of the present invention. Output value characteristic diagram, 1st
FIG. 1 is an l/lux abnormality characteristic diagram for determining abnormalities in a conventional torque sensor. In the figure, CPU: microcomputer, SP: 11-speed sensor, 1st steering wheel, 8: motor, 40: torque sensor. In addition, in the figures, the same reference numerals and the same symbols indicate the same or equivalent parts. Patent applicant Aisin Seiki Co., Ltd.

Claims (1)

[Scope of Claims] A torque sensor that detects a steering torque applied to a steering wheel, a motor that is drive-controlled to supplement the steering torque according to the output of the torque sensor, and a motor that decelerates the rotation of the motor. a reduction mechanism that transmits rotation to the steering shaft; a clutch mechanism interposed between the motor and the reduction mechanism; a rate of change detection means that detects a rate of change in the output signal of the torque sensor; The torque sensor is characterized by comprising: threshold setting means for changing the threshold value of the rate of change of the output signal of the torque sensor; and abnormality determining means for comparing the output of the rate of change detection means and the output of the threshold setting means. Electric power steering device.