JPH10329744A - Steering wheel angle correcting device in power steering device, and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To diagnose failure of a detector, which detects a discrepancy between a turning angle of a steering wheel and that of a tire, even during the execution of correction of the discrepancy. SOLUTION: When a CPU within a controller 26 detects a discrepancy between the present (steering) wheel turning angle, which is detected by a steering wheel turning angle sensor 30, and a target, wheel turning angle obtained from a tire turning angle detected by a tire (turning) angle sensor 28, the CPU opens an electromagnetic valve during the operation of the steering wheel in order to produce a slip of the steering wheel operation, thereby correcting the discrepancy. When a car speed obtained from the detection value of a car speed sensor 35 exceeds 5 km/h and when such failure conditions as ΔY=0 and moreover VT=0 (where ΔY denotes the variation of a yaw-rate Y obtained from the detection value of a yaw-rate sensor 36 during the turning of the car, while VT denotes the angular velocity of the tire, which is obtained from the detection value of a tire (turning) angle sensor 28.) are continuously satisfied for a prescribed period of time, the CPU diagnoses the tire turning angle sensor 28 as failure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering angle correcting device for a power steering device for correcting a deviation of a correspondence relationship between a steering wheel steering angle and a steering wheel turning angle in a vehicle such as a forklift equipped with a power steering device. And vehicles.

[0002]

2. Description of the Related Art Conventionally, as a power steering device,
2. Description of the Related Art An all-hydraulic power steering device that supplies an oil amount corresponding to an operation amount of a steering wheel to a steering cylinder to steer a steered wheel is known.

For example, in an industrial vehicle such as a forklift,
A knob is provided on the handle so that the handle can be operated with one hand while performing a cargo handling operation or the like. Therefore, the position of the knob may be used as a guide for judging whether or not the steered wheels are at the turning angle when traveling straight. However, the orbit roll efficiency (actual discharge amount / theoretical discharge amount) indicating the correspondence between the operation amount of the handle and the amount of oil discharged from the hydraulic oil supply device such as an orbit roll fluctuates with respect to the handle operation speed. Due to an oil leak or the like in a hydraulic system such as a steering cylinder, a deviation occurs in the correspondence between the knob position and the steering wheel turning angle.

[0004] For example, Japanese Patent Publication No. Hei 3-30544 and Japanese Patent Publication No. Hei 4-24270 disclose a steering wheel angle correction device for correcting a deviation of a steering wheel angle from a steering angle of a steered wheel. FIG. 9 shows a steering wheel angle correction device disclosed in Japanese Patent Publication No. 4-24270.

[0005] All-hydraulic power steering device 71
Are a steering unit 73 operated by a steering wheel 72, a steering cylinder 74 for steering a steered wheel (not shown), and hydraulic lines 75 and 76 connecting the steering unit 73 and the steering cylinder 74.
And One of the hydraulic lines 75 and 76 serves as a supply line for supplying pressurized hydraulic oil from the steering pump 77 during steering according to the steering direction of the steering wheel 72, and the other line supplies oil to the hydraulic oil tank 78. Return return line. An electromagnetic switching valve 80 is provided in the middle of a drain oil line 79 connecting the two hydraulic lines 75 and 76.

The control means 81 includes a steering wheel rotation angle sensor 8
A target cylinder stroke xg is obtained from the steering wheel rotation angle signal θabs from the map 2 using a map, and the deviation between the target cylinder stroke xg and the actual cylinder stroke x determined by the cylinder stroke signal s from the cylinder position sensor 83 is an allowable value. Over, the solenoid 84
And the electromagnetic switching valve 80 is opened. Thus, the electromagnetic switching valve 80 is opened, and a part of the hydraulic oil flowing through the feed line among the hydraulic lines 75 and 76 is drained to the drain oil line 7.
9 flows out (recirculates) to the hydraulic oil tank 78 and the handle 72 is idled, so that the position of the handle is corrected.

In this conventional apparatus, an abnormality in the control system such as a failure of each of the sensors 82 and 83 is diagnosed, and when an abnormality is detected, the electromagnetic switching valve 80 is forcibly closed, so that the steering wheel can be divided into steering wheel operations. Problems such as small movements in the operation of the steering wheel (uncomfortable feeling, etc.) were prevented. As a failure diagnosis method, the handle rotation speed Vh is set to the reference value V
When exceeding ho, the normal limit value Vso of the cylinder stroke speed Vs corresponding to the handlebar rotation speed Vh is obtained, and the actual cylinder stroke speed | Vs |
If it was less than this, it was determined to be a failure. That is, abnormality such as sensor failure is diagnosed by judging whether the correspondence between the detected values Vh and | Vs | from the sensors 82 and 83 is normal or abnormal.

[0008]

However, when the steering wheel rotation angle sensor 82 fails, there is a problem that the failure cannot be diagnosed or a wrong diagnosis is made. For example, if the detected value of the steering wheel rotation angle sensor 82 does not change and remains constant due to a failure despite operating the steering wheel, the steering wheel rotation speed Vh becomes “0”.
(That is, the Vh value becomes smaller than the reference value Vho), so that the failure diagnosis itself is not performed. For this reason, the failure of the cylinder position sensor 83 cannot be found. Therefore, the deviation of the steering wheel is corrected based on the erroneous detection value from the steering wheel rotation angle sensor 82, and there is a possibility that a disadvantage that the deviation amount is increased may be caused.

Further, in the conventional apparatus, during the correction of the deviation of the steering wheel, the change in the cylinder stroke is considerably smaller than the rotation amount of the steering wheel due to the idling of the steering wheel operation.
Handle rotation speed Vh and cylinder stroke speed | Vs
Can satisfy the relationship at the time of failure. Therefore, the failure diagnosis must be interrupted during the execution of the steering wheel deviation correction. However, if a failure occurs during execution of the steering wheel deviation correction and the detection value of one of the sensors 82 and 83 is fixed to a constant value, the poles whose x and xg values match during one rotation of the steering wheel. The correction remains executed except for a moment. If the correction is stopped and the failure diagnosis is performed for an extremely short time so that the failure cannot be diagnosed, the failure is not easily found. In this case, the steering operation is always idle. For this reason, it is necessary to be able to perform a failure diagnosis even during the execution of the steering wheel misalignment correction.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first object of the present invention is to detect a failure of a detector for detecting a deviation of a correspondence between a steering wheel and a steering wheel. An object of the present invention is to provide a steering wheel angle correction device and a vehicle in a power steering device that can diagnose even during execution of deviation correction. A second object is to find a failure such as a dropout failure in which a detection value of a detector for detecting a deviation of a steering wheel is fixed to a constant value within a normal range. A third object is to improve the accuracy of diagnosis. A fourth object is to reduce erroneous diagnosis caused by the detector to be diagnosed temporarily taking an inappropriate detection value. The fifth purpose is
The object of the present invention is to make it possible to restart the correction of the deviation of the steering wheel even if the diagnosis is erroneous. A sixth object is to diagnose a failure of a steering angle detector which is provided near a steered wheel and is likely to be broken due to vibration from a road surface, thereby efficiently detecting a failure due to a failure of a detector for detecting a deviation of a steering wheel. To avoid. A seventh object is to improve the accuracy of failure diagnosis by using a yaw rate detector capable of outputting a highly reliable detection value as a turning detector. An eighth object is to use a detector used for vehicle body swing regulation control for vehicle failure diagnosis.

[0011]

According to the first aspect of the present invention, there is provided a steering wheel angle detector for detecting a steering wheel angle, and a steering wheel turning angle. A steering angle detector for driving the steering wheel in accordance with the operation amount of the steering wheel, and a steering device for correcting the steering wheel turning angle change ratio with respect to the steering wheel operation amount to create a steering wheel idling state. Correction means, a turn detector that outputs a detection value necessary for measuring a change in direction of the vehicle when turning, and a change rate of the direction of the vehicle measured from the detection value of the turn detector, and the steering wheel angle The failure of at least one of the detector and the steering angle detector is determined by dividing the change in the rate of change in the direction of the vehicle such that the change in the detection value of the detector to be diagnosed with the failure is smaller than a predetermined value that can be regarded as a failure. Assert A failure diagnosis unit that performs disconnection, detects a shift in the correspondence between the steering wheel angle and the steering angle, and controls the correction unit to be driven when the steering wheel is operated in a direction to reduce the shift. A steering angle correction device for a power steering device, comprising: a control unit that does not drive the correction unit when the failure diagnosis unit diagnoses that the detector has failed.

According to a second aspect of the present invention, in order to achieve a second object, in the first aspect of the invention, the failure diagnosis means includes a change in a direction of the vehicle measured from a value detected by the turning detector. The gist of the present invention is to diagnose a failure if the detection value of the detector to be subjected to the failure diagnosis is constant despite the change in the rate.

According to a third aspect of the present invention, in order to achieve a third object, the vehicle according to the first or second aspect is provided with a vehicle speed detecting means for detecting a vehicle speed.
The gist of the failure diagnosis means is to perform a failure diagnosis when the vehicle speed detected by the vehicle speed detection means is equal to or higher than a predetermined speed.

According to a fourth aspect of the present invention, in order to attain the fourth object, in the first aspect of the present invention, the failure diagnosis means includes detecting the turning detector. A failure occurs when a failure diagnosis condition in which a change in a detection value of the detector targeted for failure diagnosis is reduced to less than the predetermined value for a predetermined period of time is continuously satisfied for a change in a change rate of the direction of the vehicle measured from the value. The point is to make a diagnosis.

According to a fifth aspect of the present invention, in order to attain the fifth object, in the first aspect of the present invention, the failure diagnosis means determines that the failure has occurred. The gist of the present invention is to cancel the failure diagnosis result if the failure diagnosis condition based on which the diagnosis is made is not satisfied.

According to a sixth aspect of the present invention, in order to achieve the sixth object, in the first aspect of the present invention, the failure diagnosis means includes a failure diagnosis target for performing a failure diagnosis. The detector is the steering angle detector.

According to a seventh aspect of the present invention, in order to achieve the seventh object, in the first aspect of the present invention, the turning detector detects a yaw rate of the vehicle. It is a detector.

In order to achieve the eighth object, according to the invention described in claim 8, in the invention described in claim 7, the yaw rate detector detects that the lateral G of the vehicle obtained from the product of the yaw rate and the vehicle speed of the vehicle. When a value equal to or more than a predetermined value is taken, the vehicle body swing regulation control that regulates the swing of the steerable wheels that can swing to the body,
It is provided on the vehicle to detect a detected value of the yaw rate used for calculating the lateral G.

According to a ninth aspect of the present invention, a vehicle is provided with the steering wheel angle correcting device according to any one of the first to eighth aspects. (Operation) Therefore, according to the first aspect of the invention, the steered wheels are steered by the driving means in accordance with the operation amount of the steering wheel. If a deviation in the correspondence between the steering wheel angle detected by the steering angle detector and the steering angle of the steering wheel detected by the steering angle detector is detected, the control means corrects when the steering wheel is operated in a direction to reduce the deviation. Drive the means. By driving the correction means, the steering wheel turning angle change ratio with respect to the operation amount of the steering wheel is corrected to be small, an idling state of the steering wheel operation is created, and the deviation is corrected.

At least one of the steering wheel angle detector and the steering angle detector is diagnosed by the failure diagnosis means. The failure diagnostic means measures the rate of change in the direction of the vehicle using the detected value of the turning detector, and the change in the detected value of the detector to be diagnosed is determined by the change in the rate of change in the direction of the vehicle. If the value is smaller than a predetermined value that can be regarded as a fault, the detector is diagnosed as having failed. When a failure is found by the failure diagnosis means, the control means does not drive the correction means. In other words, the shift correction of the steering wheel is not performed.

According to the second aspect of the present invention, the failure diagnosing means detects the failure of the detector to be diagnosed in spite of the fact that the change rate of the direction of the vehicle measured from the detection value of the turning detector changes. If there is no change in the detected value, the detector to be diagnosed as a failure is diagnosed as a failure.

According to the third aspect of the present invention, the failure diagnosis means performs a failure diagnosis when the vehicle speed detected by the vehicle speed detection means is equal to or higher than a predetermined speed. When the steering angle of the steered wheels changes, the rate of change in the direction of the vehicle increases as the vehicle speed increases, and the failure diagnosis is performed only at a vehicle speed equal to or higher than a predetermined speed, thereby increasing the accuracy of the failure diagnosis.

According to the fourth aspect of the present invention, the failure diagnosing means is configured so that the change in the detection value of the detector to be diagnosed becomes smaller than a predetermined value for a change in the rate of change in the direction of the vehicle. When the condition is continuously satisfied for a predetermined time, a failure is diagnosed. For this reason, even if the detector to be fault-diagnosed has a transient and inappropriate detection value, it is not erroneously diagnosed as a fault.

According to the fifth aspect of the present invention, if the failure diagnosis condition based on the failure diagnosis is not satisfied, the failure diagnosis means cancels the failure diagnosis result.
For this reason, even if the execution of the deviation correction of the steering wheel is temporarily prohibited due to the erroneous diagnosis, the execution of the deviation correction of the steering wheel is restarted if the erroneous diagnosis is found.

According to the sixth aspect of the present invention, the failure diagnosis means diagnoses the failure of the steering angle detector which is provided near the steered wheels and which is relatively susceptible to failure due to vibration from the road surface.
According to the invention described in claim 7, since the yaw rate which is the detection value of the yaw rate detector corresponds to the change rate of the direction of the vehicle, the change in the detection value of the yaw rate detector and the detection value of the detection value of the detector to be diagnosed are determined. Failure diagnosis can be performed only by comparing the change. In addition, since the yaw rate detector outputs a relatively reliable detection value, the accuracy of failure diagnosis is improved.

According to the present invention, when the lateral G of the vehicle becomes equal to or more than a predetermined value, the vehicle body swing regulation control for regulating the swing of the steered wheels provided to be able to swing on the body is performed. A yaw rate detector provided in the vehicle for detecting a yaw rate required for calculating the lateral G used in this control is used for failure diagnosis.

According to the ninth aspect of the present invention, the vehicle is provided with the steering wheel angle correcting device according to any one of the first to eighth aspects. The same effects as those of the invention described in any one of 8 are obtained.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a power steering device 1 mounted on a forklift F as a vehicle. A steering wheel (steering wheel) 2 that is rotated by an operator is provided with a knob 2a for improving the operability. A steering shaft 3 that supports the handle 2 is connected to an orbit roll 4 that constitutes driving means.

A valve unit 5 constituting the orbit roll 4 is supplied to a supply pipe 7 to which hydraulic oil from a hydraulic pump (loading pump) 6 driven by an engine (not shown) is supplied, and to a drain tank 8. A discharge pipe 9 for discharging oil is connected. A relief valve 11 is interposed in a conduit 10 connecting the supply pipe 7 and the discharge pipe 9, and the relief valve 11 keeps a hydraulic pressure fed from the hydraulic pump 6 to the valve unit 5 at a constant pressure (set pressure). It has become so.

The valve unit 5 is driven directly by the steering shaft 3 and has a function of supplying an oil amount proportional to the rotation amount of the handle 2 to a steering cylinder 12 which constitutes a driving means described later. is there. The valve unit 5 and the steering cylinder 12 are 2
The two hydraulic lines 13 and 14 are connected. When the handle 2 is turned to the right, the hydraulic line 13
The hydraulic line 14 functions as a return line for returning hydraulic oil to the hydraulic pump 6. When the steering wheel 2 is turned to the left,
The hydraulic line 14 functions as a feed line, and the hydraulic line 13 functions as a return line.

The steering cylinder 12 has a hollow cylindrical cylinder tube 15 fixed to the vehicle body, a piston 16 reciprocally disposed inside the cylinder tube 15, and a pair of left and right pistons extending from both ends of the cylinder tube 15. Rods 17a and 17b are provided. Each hydraulic line 1
Each of the cylinders 3 and 14 is communicated with each chamber of a cylinder tube 15 divided into two chambers by a piston 16.

Left and right steering wheels (rear wheels) 19, 19 are connected to the distal ends of the piston rods 17a, 17b via link mechanisms 18a, 18b, and when the steering cylinder 12 is driven, both steering wheels are steered. The wheels 19 are steered left and right about the kingpin 20.

The hydraulic lines 13 and 14 are connected by a bypass line 21, and an electromagnetic switching valve 22 and a throttle valve 23 as correction means are provided in the bypass line 21. The electromagnetic switching valve 22 reduces a part of the oil amount discharged from the valve unit 5 by the opening thereof to the bypass line 2.
In this case, the steering wheel 2 is returned to the drain tank 8 via the valve 1 to reduce the ratio of the displacement of the piston 16 in the steering cylinder 12 to the operation amount of the handle 2, thereby creating an idling state of the handle 2.

The electromagnetic switching valve 22 is a normally closed type two-position switching valve. A spool (not shown) constituting the electromagnetic switching valve 22 is urged by a spring 24 toward the shut-off position. The electromagnetic switching valve 22 is in a shut-off position (FIG. 1) for shutting off the bypass line 21 when the solenoid 25 is demagnetized.
), And is placed at a communication position for connecting the bypass line 21 when the solenoid 25 is excited. Excitation and demagnetization of the solenoid 25 are controlled by a controller 26. The throttle valve 23 is provided so that the steering line 19 can be steered by the steering wheel operation even if the electromagnetic switching valve 22 remains open due to a failure or the like.
1 is for reducing the flow rate.

The forklift F has a sensor for detecting a deviation of the correspondence between the steering wheel angle and the steering angle.
An encoder (rotary encoder) 27 as a steering wheel angle detector for detecting rotation of the steering wheel 2 and a tire angle sensor 28 as a steering angle detector for detecting a tire turning angle of the steered wheels 19 are provided. I have.

The encoder 27 includes the steering shaft 3
A disk 29 is provided so as to be integrally rotatable with the camera, and a handle angle sensor 30 including three sets of photocouplers for detecting light passing through slits of the disk 29 is provided. A detection signal from the steering wheel angle sensor 30 is input to the controller 26.

The steering angle sensor 30 includes a first transistor 31, a second transistor 32, and a correction transistor 3 which are phototransistors constituting the photocoupler.
3 (shown in FIG. 2). First transistor 3
The first and second transistors 32 are for detecting light passing through a total of 40 slits formed at equal intervals on the disk 29 along the circumferential direction, and turn on / off by one rotation of the handle 2. The detection signals (digital signals) SS1 and SS2 shown in FIG. Each of the transistors 31, 32 has its own output signal SS1, SS2
Are set so that the phases of the two signals S
By detecting the edges of S1 and SS2, handle 2
Can be detected with a resolution equivalent to 160 divisions of one rotation of the steering wheel.

The correction transistor 33 is for detecting light passing through a position correcting slit formed at one peripheral portion of the disk 29. When the steering wheel 2 is disposed at the neutral position (the normal steering wheel angle when the steering wheel 19 is at the steering angle when traveling straight ahead), the correction transistor 33 detects light passing through the slit and turns on when the steering wheel 19 is turned on.
The detection signal (digital signal) SSC shown in FIG. The output signal SSC from the correction transistor 33 is the signal SS
It is used for calibration of a count value C, which will be described later, which corresponds to a steering wheel angle obtained by counting the edges of 1, SS2.

The tire angle sensor 28 comprises a potentiometer in this embodiment. The tire angle sensor 28 is attached to the right end of the rear axle beam with its detection axis rotatable integrally with the king pin 20 supporting the right steering wheel 19. The tire angle sensor 28 outputs to the controller 26 a detection signal that detects the amount of rotation of the king pin 20.

A front differential ring gear 34 for transmitting an output from an engine (neither is shown) to the left and right front wheels as driving wheels is provided with a vehicle speed sensor 35 as a vehicle speed detecting means. The vehicle speed sensor 35 detects the rotation of the front differential ring gear 34 and outputs a vehicle speed signal v having a frequency proportional to the vehicle speed to the controller 26.

A forklift F has a yaw rate sensor 36 as a turning detector and a yaw rate detector mounted on the vehicle body. The yaw rate sensor 36 outputs a detection signal corresponding to the angular velocity (yaw rate) of the forklift F at the time of turning to the controller 26.

The rear axle beam (not shown) for supporting the left and right steering wheels 19 is swingably supported at its left and right ends with respect to the vehicle body frame so as to be vertically displaceable. It can be tilted left and right (vehicle width direction). In this embodiment, a swing regulating device 39 including a hydraulic damper 37 and an electromagnetic switching valve 38 is provided to regulate the swing of the rear axle beam with respect to the vehicle body frame.

The hydraulic damper 37 is interposed between the rear axle beam and the vehicle body frame. The solenoid-operated directional control valve 38 is divided into two sections by a piston in a cylinder of the hydraulic damper 37.
It is provided on the oil passage connecting the chambers. The hydraulic damper 37 is in a free state in which it can expand and contract when the electromagnetic switching valve 38 is opened,
When the electromagnetic switching valve 38 is closed, it is locked so that it cannot expand or contract.

In this embodiment, when the lateral G acting on the vehicle becomes larger than a predetermined value, the controller 26 performs swing control (oscillation restricting control) for locking the hydraulic damper 37 and restricting the vehicle body from tilting in the lateral direction. . The lateral G of the vehicle is determined by the product of the yaw rate (turning angular velocity) Y (deg./sec.) Obtained from the detected value of the yaw rate sensor 36 and the vehicle speed V (km / h) obtained from the detected value of the vehicle speed sensor 35. And the equation Gs = V
Y (where Gs is the calculated value of the horizontal G). Gs
When the value exceeds a predetermined value Go set in advance, the electromagnetic switching valve 38
The solenoid 38a is demagnetized to lock the hydraulic damper 37.

In the present embodiment, of the two sensors 28 and 30 provided for detecting the deviation of the correspondence between the steering wheel angle and the steering angle, the two sensors 28 and 30 are disposed in a place where they are likely to be subjected to severe vibrations during running. The failure of the tire angle sensor 28 whose occurrence rate is relatively high is diagnosed. The tire angle sensor 28 composed of a potentiometer is liable to cause a falling-off failure or the like in which a detection axis of the tire angle sensor 28 is disengaged from the king pin 20 so that it cannot be integrally rotated. In the present embodiment, the yaw rate sensor 36 attached to the vehicle body for swing control is used for failure diagnosis of the tire angle sensor 30.

As shown in FIG. 2, the controller 26
Microcomputer 40, edge detection circuit 41, AD
Conversion circuit 42 and excitation / demagnetization drive circuit 4 constituting control means
3 and so on. The microcomputer 40 includes a central processing unit (CP) constituting control means and failure diagnosis means.
U) 44, a read only memory (ROM) 45, a read / write rewritable memory (RAM) 46, a steering counter 47, a control cycle counter 48, an error counter 49 constituting a failure diagnosis means, an input interface 50 and an output interface 51. Have.

Each detection signal SS from the first transistor 31, the second transistor 32 and the correction transistor 33
1, SS2 and SSC are input to the CPU 44 via the input interface 50. The edge detection circuit 41 detects the rising and falling edges of the detection signals SS1, SS2, and SSC, and outputs edge signals SE1, SE2, and SEC when the edge is detected. Therefore,
The edge signals SE1 and SE2 are alternately input to the CPU 44 every time the handle 2 is operated by 1/160 of a rotation (= 2.25 °). The detection signals detected by the tire angle sensor 28, the vehicle speed sensor 35, and the yaw rate sensor 36 are input to the CPU 44 via the A / D conversion circuit 42. The CPU 44 counts the number of pulses of the vehicle speed signal v from the vehicle speed sensor 35 by a counter (not shown), and obtains the vehicle speed V from a change in the count value per unit time.

The steering counter 47 is for counting the steering wheel angle θ of the steering wheel 2. The CPU 44 changes the count value C of the steering counter 47 by "1" each time the edge signals SE1 and SE2 are input, that is, each time the steering wheel 2 is rotated by 1/160. Accordingly, the steering angle 47 indicating the relative position of the knob 2a is provided in the steering counter 47.
Is counted as a count value C of “0 to 159”. Each time the CPU 44 inputs an edge signal SEC that detects that the knob 2a is located at the neutral position, the count value C is calibrated to “80” (the count value corresponding to the steering wheel angle “0 °”). ing.

The control cycle counter 48 indicates that the handle 2 is 1
This is for counting the count value C1 corresponding to the required time required during / 160 rotations. The CPU 44 increments the count value C1 every time a later-described knob position correction control process executed every predetermined time to (for example, 10 milliseconds in the present embodiment) is performed, and every time the count value C of the steering counter 47 is changed, That is, handle 2 is 1/1
The count value C1 is cleared every 60 rotations. If the count value C1 is equal to or greater than the set value Co, it is determined that the steering operation is stopped.

The error counter 49 is provided for the tire angle sensor 2
8 is used to count the time during which a later-described failure condition is satisfied, which is used in the failure diagnosis, as a count value Ck. Further, the solenoids 25 and 38a are individually controlled to be excited and demagnetized by an excitation and demagnetization signal output from the CPU 44 to the excitation and demagnetization drive circuit 40 via the output interface 48. The solenoid 25 is energized when the knob position is corrected to generate the idling state of the steering wheel operation, and is demagnetized in other normal times. The solenoid 38a is excited when the swing of the rear axle beam is free, and is demagnetized when locked.

In the ROM 42, a steering wheel angle (hereinafter, referred to as a target steering wheel angle) θg indicating a normal position of the knob 2a determined from the tire turning angle R obtained by the CPU 44 from the value detected by the tire angle sensor 28, and a tire turning angle R The map M1 shown in FIG. Map M1
Is used to calculate the target steering wheel angle θg from the tire turning angle R.
(Acquired as a target steering count value Cg corresponding to the count value C of the steering counter 47 in the processing of the CPU 44) is determined by the steering wheel relative angle. A control target line L for associating the tire turning angle R with the target steering wheel angle θg has an orbit roll efficiency of 100%.
This is an ideal line on the premise of As shown in FIG. 4, the tire turning angle R is obtained by changing the detection value of the tire angle sensor 28 when the steered wheels 19 are in a straight traveling state to the turning angle “0 °”.
For example, it is detected to take a negative value during left steering and a positive value during right steering.

The ROM 45 has program data for the sensor failure diagnosis process shown in the flowchart of FIG. 6, program data for the knob position correction control process shown in the flowcharts of FIGS. 7 and 8, and program data for the swing control process (not shown). Etc. are stored. The CPU 44 executes the knob position correction control process shown in FIG. 7 at intervals of a predetermined time to (for example, 10 milliseconds). In the sensor failure diagnosis processing shown in FIG. 6, this knob position correction control processing is performed a plurality of times (for example, 5 to 5).
10) is executed once every time it is executed. The interrupt routine shown in FIG.
When the edge signal SEC is input, the calibration of the count value C of the steering counter 47 is executed by an interrupt process each time the signal SE1 or SE2 is input.

The knob position correction control processing includes the steering wheel angle θ.
When the correspondence between the steering angle and the tire turning angle R is deviated, the electromagnetic switching valve 22 is opened to generate idling in the operation of the steering wheel, thereby correcting the knob 2a to a normal position. The presence or absence of the deviation of the knob 2a is calculated by calculating a deviation amount δ between the current steering wheel angle θ and the target steering wheel angle θg determined from the tire turning angle R, and this deviation amount δ is set to an allowable value δo (for example, about 5 ° in the present embodiment). ) Is exceeded. Here, the deviation amount δ means the deviation amount in the shortest path between the current knob position and the target knob position in FIG. That is, the deviation amount δ is obtained by δ = Δθ when the deviation Δθ (= | θ−θg |) is 180 ° or less, and δ = 360 ° −Δθ when the deviation Δθ exceeds 180 °.

In this embodiment, when the deviation amount δ exceeds the allowable value δo, the current knob position approaches the target knob position by the shortest path as shown in FIG. The target direction approaching within ° (a
Only when the handle 2 is operated in (1, a2 direction)
The electromagnetic switching valve 22 is opened. Therefore,
When the handle 2 is operated in the x1 and x2 directions in the same drawing such that the current knob position does not approach the target knob position within 180 °, even if the deviation amount δ exceeds the allowable value δo, the electromagnetic switching valve 22 It is set not to open.

The interrupt routine shown in FIG.
Each time is changed by 1/160 rotation, the steering direction (operation direction) of the steering wheel 2 is detected, the steering counter 47 is counted, the control cycle counter 48 is cleared, and the steering operation stop is determined. This interrupt routine is a process for preparing necessary data in the knob position correction control process of FIG. The steering direction of the steering wheel 2 is determined by using the signals SS1, SS2, SE1, and SE2.
As shown in FIG. 3, when the phase of the signal SS1 lags behind the phase of the signal SS2 by 90 °, “right steering”, the signal SS1
Is determined to be "left steering" when the phase of the signal is ahead of the phase of the signal SS2 by 90 degrees.

The sensor failure diagnosis processing shown in FIG. 6 is processing for failure diagnosis of the steering wheel angle sensor 28. In the present embodiment, the turning angle of the steered wheels 19 changes even though the rate of change in the direction of the vehicle changes with time and the turning radius changes with time when the forklift F runs and turns. If not, the tire angle sensor 2
No. 8 failures (mainly drop-out failures) are diagnosed.
The change rate of the direction of the vehicle is monitored by monitoring the change over time of the change rate of the direction of the vehicle by looking at the yaw rate change ΔY which is the change of the yaw rate Y obtained from the value detected by the yaw rate sensor 36. The change in the turning angle of the steered wheels 19 is determined by looking at the tire angular velocity VT obtained by taking the time change ΔR of the data of the tire turning angle R obtained from the value detected by the tire angle sensor 28. By the way, when the forklift F is running at a low speed, it is difficult to obtain a reliable failure diagnosis result because the yaw rate change ΔY is slower than the tire angular velocity VT. For this reason, in this embodiment, in order to increase the reliability of the diagnosis result of the failure diagnosis, the failure diagnosis is performed only when the vehicle speed V exceeds 5 km / h.

Therefore, in the present embodiment, the vehicle speed V> 5 km
/ H and tire angular velocity VT despite ΔY> 0
= 0 is set as a failure condition for diagnosing a falling failure of the tire angle sensor 28. However, a failure is not immediately diagnosed when the failure condition is satisfied, but a diagnosis result is determined that the failure is determined only after the failure condition has been satisfied for a certain period of time. The error counter 49 is for counting the duration time when the failure condition is satisfied. The fixed time is set to, for example, about 0.5 to 1 second. Even if the vehicle speed V is greater than 5 km / h, if the vehicle speed changes, the correlation between ΔY and VT decreases. However, since this fixed time is extremely short, about 0.5 to 1 second, the vehicle speed V is substantially reduced. Since it can be considered constant, the change in the vehicle speed V is not considered.

In this embodiment, when the count value Ck of the error counter 49 becomes "10" corresponding to a predetermined time, the tire angle sensor 28 is diagnosed as having failed. CPU
44 increments the count value Ck by "1" below "10" when the failure condition is satisfied, and decrements the count value Ck by "1" above "0" when the failure condition is not satisfied.

The CPU 44 has a failure flag for storing that the tire angle sensor 28 has been diagnosed as having a failure. The flag value F of the failure flag is the error counter 49
Is set to "1" when the count value Ck becomes "10", and is cleared to "0" when the count value Ck becomes "0". For this reason, even after the tire angle sensor 28 is once diagnosed as a failure, if the failure condition is not satisfied for a certain period of time, the result of the failure diagnosis is canceled.

Next, the operation of the power steering device 1 will be described. When operating the forklift F,
The operator operates the handle 2 while holding the knob 2a.
When the steering shaft 3 is rotationally driven by operating the steering wheel 2, hydraulic oil having an oil amount corresponding to the operation amount of the handle 2 is discharged from the valve unit 5 to the steering cylinder 12, and the steering is performed according to the operation amount of the handle 2. The wheel 19 is steered. The position of the knob 2a is changed to the position of the steering wheel 1 due to a decrease in the orbit roll efficiency due to a low handle operation speed or an oil leak in a hydraulic system such as the steering cylinder 12.
9 may gradually deviate from the regular position corresponding to the turning angle of 9.

During the key-on of the forklift F, the detection signals SS1, SS from the transistors 31, 32, 33
2, SSC and the edge signal S from the edge detection circuit 41
E1, SE2, and SEC, and detection signals from the tire angle sensor 28, the vehicle speed sensor 35, and the yaw rate sensor 36 are input to the CPU 44.

The CPU 44 sets a predetermined time to (10 milliseconds).
Every time the knob position correction control process is executed a plurality of times, the sensor failure diagnosis process shown in FIG. 6 is executed once. Also, the edge signals SE1, SE2
Each time is input, the interrupt routine of FIG. 8 is executed by an interrupt process. First, the interrupt routine shown in FIG. 8 will be described.
When the CPU 44 receives the edge signals SE1 and SE2, it executes an interrupt routine by interrupt processing. At the time of execution of this routine, the handle 2 is set in the control cycle counter 49 by 1/160.
A count value C1 corresponding to a required time required for rotation is counted.

First, in step 210, detection processing of the steering direction of the steering wheel is performed. Each signal SS1, SS2, SE
1, when the phase of the signal SS1 lags behind the phase of the signal SS2 by 90 °, "1" is set in the steering direction flag, and the signal S1 is set.
When the phase of S1 leads the phase of signal SS2 by 90 °, the steering direction flag is reset to “0” as “left steering” (see FIG. 3).

At step 220, the steering counter 47 counts. That is, the count value C is incremented when the steering is "right steering",
When it is "left steering", the count value C is decremented. However, when incrementing “159”, the count value C is set to “0”, and when decrementing “0”, the count value C is set to “159”. Thus, the steering counter 47 counts the count value C corresponding to the steering wheel angle θ.

In step 230, the control cycle counter 4
It is determined whether or not the count value C1 of No. 8 is equal to or greater than the set value Co. If the count value C1 is equal to or greater than the set value Co,
In step 240, "steering operation stop determination" is made, and "1" is set to the steering stop determination flag. Also,
If the count value C1 is less than the set value Co, the steering stop determination flag remains reset to "0" at the start of the interrupt routine. Then, in step 250, the control cycle counter 48 is cleared.

As described above, when executing the knob position correction control process, the current steering wheel angle θ can be determined from the count value C of the steering counter 47, the current steering direction of the steering wheel can be determined from the flag value of the steering direction flag, and the steering stop determination flag can be determined. From the flag value, it can be determined whether or not the steering operation is stopped.

Next, the sensor failure diagnosis processing will be described with reference to the flowchart of FIG. The sensor failure diagnosis process is executed, for example, every 50 to 100 milliseconds every time the knob position correction control process is executed a plurality of times. Further, the CPU 44 detects the vehicle speed V from the pulse frequency of the vehicle speed signal v.

First, at step 510, the vehicle speed V, the yaw rates Y and Y1, and the current tire turning angles R and R1 are read. Y1 and R1 are data of the yaw rate and the tire turning angle before the predetermined time n · to before stored in the RAM 46, respectively. In step 520, the yaw rate change ΔY
(= | Y−Y1 |) is calculated. In step 530, the tire angular velocity VT (= | R-R1 |) is calculated.

In the next step 540, the vehicle speed V is 5 km
/ H is determined. When the vehicle is running at low speed where V <5 km / h is satisfied, it is not suitable for failure diagnosis.
Go to 0. When V> 5 km / h is satisfied and the vehicle is running at a vehicle speed exceeding 5 km / h, the process proceeds to the next step 550.

In step 550, the yaw rate change ΔY
Takes a positive value, that is, whether the yaw rate Y changes. If the yaw rate change ΔY is not 0 and the rate of change in the direction of the vehicle is assumed to be constant, the flow proceeds to step 590 because the change is not suitable for failure diagnosis. Yaw rate change Δ
If Y> 0 holds and it is recognized that the turning radius of the vehicle has changed and the rate of change of the direction of the vehicle has changed, the process proceeds to the next step 560.

In step 560, it is determined whether or not the tire angular velocity VT is "0", that is, whether or not the tire turning angle R has not changed and remains constant. Normally, if the steering wheel 2 is turned while the vehicle is running at a vehicle speed V exceeding 5 km / h, the steered wheels 19 are turned off, the turning radius of the vehicle changes over time, and the rate of change of the direction of the vehicle changes. Therefore, the yaw rate change ΔY> 0. At this time, if the tire turning angle sensor 28 is normal, the tire angular velocity VT> 0, so that the failure condition is not satisfied and the routine proceeds to step 580. Then, at step 580, the count value Ck of the error counter 49 is obtained.
Is decremented by 0 or more. For this reason, the error count value Ck is normally "0". Therefore, at step 590, it is determined that the error count value Ck is not "10", and at step 610, it is determined that the error count value Ck is "0". Then, the process proceeds to step 620 to clear the failure flag (the failure flag F = 0).

On the other hand, if a falling-off failure occurs in which the detection axis of the tire angle sensor 28 is disengaged from the kingpin 20, the detection value of the tire angle sensor 28 does not change even if the steering wheel 19 is cut off. Therefore, when traveling at a vehicle speed V exceeding 5 km / h, the yaw rate change ΔY takes a positive value, a change in the turning radius of the vehicle is detected, and the turning angle of the steered wheels 19 should have changed. Nevertheless, the tire angle sensor 28
No change is observed in the tire turning angle R obtained from the detected values of the above, and the tire angular velocity VT is detected as "0". That is, V>
At 5 km / h, the fault condition of ΔY> 0 and VT = 0 is satisfied (S540 to S560).

If VT = 0 at step 560 and the failure condition is satisfied, at step 570, the error count value Ck of the error counter 49 is incremented by 10 or less. Even if the failure condition is satisfied, the failure flag is not set until the established time does not continue for a fixed time, that is, while the error count value Ck does not reach 10. For this reason,
When the tire angle sensor 28 is normal, the failure flag is not set even if the failure condition happens to be temporarily satisfied by some instability factor. Then, the tire angle sensor 28 really fails and the failure condition is continuously satisfied for a certain period of time. In step 590, the failure flag is set only when the error count value Ck reaches "10" (F = 1).

Even if the failure condition continues for a predetermined period of time and the failure flag is set for some reason even though the tire angle sensor 28 is normal, the VT is determined in step 560. = 0, the failure condition is not satisfied, and this unsatisfied state continues for a certain period of time, and the error count value Ck becomes “0” again.
In step 620, the failure flag is cleared. Even if an erroneous diagnosis is made in this way, once it is confirmed that the diagnosis is normal, the diagnosis result once diagnosed as a failure is canceled. The flag value F of the failure flag is used for determining whether or not to execute the knob position correction in the knob position correction control processing.

Next, the knob position correction control processing will be described with reference to the flowchart of FIG. First, step 1
At 0, the control cycle counter 45 is incremented. In the next step 20, the current steering wheel angle θ and tire turning angle R are read. In processing, the count value C of the steering counter 44 is read as the steering wheel angle θ.

In step 30, the map M1 shown in FIG.
Is used to determine the target steering wheel angle θg (the target steering count value Cg in the processing) from the tire turning angle R. Step 40
Then, the target direction in which the knob deviation correction can be completed in the shortest path is calculated. That is, the steering wheel steering direction that requires the shortest path from the current knob position to the target knob position is determined. In the processing, if the deviation ΔC = | C−Cg | is equal to or less than “80” (that is, 180 ° in terms of steering wheel angle), C <
When Cg, the target direction is determined to be “rightward”, and when C> Cg, the target direction is determined to be “leftward”. When the deviation ΔC exceeds “80”, it is determined that the target direction is “left” when C <Cg, and that the target direction is “right” when C> Cg. The target direction flag is cleared to “0” when the target direction is “left” and “1” when the target direction is “right”.
Is set.

In step 50, the deviation δ of the knob 2a is calculated from the steering wheel angle θ and the target steering wheel angle θg. The deviation amount δ is δ = Δθ when the deviation Δθ (= | θ−θg |) ≦ 180 °, and δ when the deviation Δθ> 180 °.
= 360 °-Δθ. This shift amount δ is also calculated in processing using the count values C and Cg.

In step 60, a failure flag is checked.
When the flag value F of the failure flag is 1, the routine proceeds to step 110, where a valve closing command for outputting a degaussing signal for degaussing the solenoid 25 is performed. That is, when the tire angle sensor 28 is diagnosed as having failed, the opening of the electromagnetic switching valve 22 is substantially prohibited, and the execution of the knob position correction is prohibited. Therefore, when the knob position correction is performed when the tire angle sensor 28 fails, the remarkable deterioration of the steering wheel operation which can occur can be avoided, and the steering wheel feeling can be maintained well even when the tire angle sensor 28 fails. .

In step 70, it is determined whether or not the steering operation is stopped. If the steering stop determination flag is set to "1", it is determined that the steering operation is stopped, and a valve close command is issued in step 110. That is, the electromagnetic switching valve 22 is not opened while the steering operation is stopped.

In the next step 80, it is determined whether or not the deviation amount δ is equal to or smaller than the allowable value δo. The deviation δ is the allowable value δ
If it is equal to or less than 0, there is no need to perform the knob deviation correction, so a valve close command is issued in step 110. on the other hand,
When the deviation amount δ exceeds the allowable value δo, the routine proceeds to step 90.

In step 90, it is determined whether the steering direction matches the target direction. If the flag values of the steering direction flag and the target direction flag do not match, and the steering wheel 2 is operated in the opposite direction to the target direction in which the shift correction of the knob 2a can be completed in the shortest path, and the steering direction does not match the target direction,
In step 110, a valve close command is issued. If the flag values of the steering direction flag and the target direction flag match, and the steering wheel 2 is operated in the target direction in which the shift of the knob 2a can be corrected in the shortest path, and the steering direction matches the target direction, in step 100, Issue a valve open command. That is, as shown in FIG. 5, when the handle 2 is operated in the a1 and a2 directions in which the current knob position approaches the target knob position by the shortest path, the electromagnetic switching valve 22 is opened, and the handle is operated in the x1 and x2 directions. 2 is operated, the electromagnetic switching valve 22 is not opened. Therefore, when the knob position correction is performed, the deviation is always reduced.

Even if the knob 2a is displaced by more than one rotation, only the relative angle of the handle is considered, so that the position of the knob 2a is corrected by a correction amount of a fraction smaller by one rotation, for example. Further, when the knob 2a is less than one rotation but deviates by more than 180 °, by performing the correction of deviating by one rotation, the correction amount of the knob 2a can be smaller than the actually deviated amount.

As described in detail above, according to the present embodiment,
The following effects can be obtained. (1) Despite the fact that the yaw rate Y obtained from the detected value changes during running using the yaw rate sensor 36 and the steering angle of the steered wheels 19 should change, the detected value of the tire angle sensor 28 is used. Since the tire angular velocity VT is "0" and the diagnostic method of diagnosing the tire angle sensor 28 as a failure is adopted, the failure of the tire angle sensor 28 can be found even during idling of the steering wheel operation. For this reason,
Since the failure diagnosis of the tire angle sensor 28 can be performed even during the execution of the knob position correction, the failure of the tire angle sensor 28 can be found without fail even during the knob position correction, and the abnormal knob position correction can be reliably stopped. Accordingly, it is possible to prevent a problem that the idle operation of the steering wheel is left unattended when the sensor fails, which is a problem in the conventional device in which the failure diagnosis cannot be performed during the execution of the steering wheel deviation correction.

(2) Since the failure diagnosis is performed only at the vehicle speed V exceeding 5 km / h, a highly reliable failure diagnosis can be realized. (3) Since the failure is diagnosed only when the failure condition is continuously satisfied for a certain period of time, even though the tire angle sensor 28 is normal, it happens to be transient due to some instability factor. Even if the failure condition is satisfied, no erroneous diagnosis is caused. Further, when the steered wheel 19 slips at a constant turning angle during turning, ΔY> 0 and VT = 0 may be satisfied and the failure condition may be satisfied, but a slight slip during traveling may occur within a certain time. Since it fits in, erroneous diagnosis due to slip can be almost certainly eliminated.

(4) Even if the tire angle sensor 28 is erroneously diagnosed as a failure, if the failure condition continues to be unsatisfied for a certain period of time and the error count value Ck becomes 0, the diagnosis result that the failure has been determined is canceled. As a result, even if a malfunction is erroneously diagnosed, if the tire angle sensor 28 is normal, the knob position correction can be immediately restored. Also, if the steered wheel 19 slips for a relatively long time while being fixed at a fixed turning angle,
Although a malfunction may be diagnosed, the knob position correction is restored as soon as the vehicle returns to the normal running state. In addition, when the vehicle slips relatively large, a malfunction is diagnosed and the idling operation of the steering wheel 2 is stopped even during the knob position correction, which is rather convenient.

(5) Since the yaw rate sensor 36 provided on the vehicle for the swing control is used for the failure diagnosis of the tire angle sensor 28, it is not necessary to provide a dedicated sensor for the failure diagnosis.

(6) Since the knob position correction for correcting the deviation by the relative angle of the steering wheel is adopted, even if the rotation is actually more than one rotation, the correction amount can be reduced by, for example, a fraction smaller by one rotation. Unnecessary idling can be reduced.

(7) Since the electromagnetic switching valve 22 is opened only when the handle 2 is operated in the target direction in which the deviation of the knob 2a can be corrected in the shortest path, the knob 2 is actually opened.
Even if a is less than one rotation and exceeds 180 °, the rotation is shifted by one rotation, so that the idling amount of the steering wheel operation required for the knob position correction can be reduced. In addition, if the knob position correction is executed, the blur can be reduced.

The present invention is not limited to the above embodiment, but can be embodied as follows without departing from the spirit of the invention. (N) The turning detector is not limited to the yaw rate sensor.
Other detectors capable of detecting the direction (azimuth) in the absolute space can be employed as the turning detector. For example, an orientation sensor may be used. When the direction sensor is used, the time change Δh of the detected value h of the direction sensor is a value corresponding to the yaw rate. Therefore, in order to obtain a value corresponding to the yaw rate change ΔY, the detected value change Δh before and after the lapse of a predetermined time is used. It is necessary to take the difference Δh−Δh1 of Δh1. Then, this difference is regarded as a yaw rate change ΔY, and when ΔY> 0 and ΔR = 0, a failure (dropout failure) may be diagnosed.

(M) The fault condition is not limited to when ΔY> 0 and ΔR = 0. That is, when the value of ΔR is smaller than the value of ΔY, a failure condition is set, for example, ΔR /
A failure may be diagnosed when ΔY <A (set value) is satisfied. However, in the range where ΔY is close to 0, the error of the ΔR / ΔY value increases, so it is desirable to avoid the diagnosis.

(P) An acceleration sensor is employed as the turning detector, and the lateral G detected by the acceleration sensor is divided by the vehicle speed V obtained from the value detected by the vehicle speed sensor 35 to calculate the yaw rate Y of the vehicle. Using the obtained yaw rate Y, the change in the change rate of the direction of the vehicle and the tire angular velocity VT of the steered wheels 19 are obtained.
And a failure diagnosis method for determining whether a failure condition is satisfied between the two.

(R) As described in the prior art, in the steering wheel angle correction control based on the steering wheel absolute angle for obtaining the target cylinder stroke from the steering wheel angle and adjusting the actual cylinder stroke to the target cylinder stroke,
The present invention may be implemented.

(Q) The failure of the steering wheel angle sensor 30 (encoder 27) may be diagnosed using the detected value of the yaw rate sensor 36. The failure diagnosis of both the tire angle sensor 28 and the steering wheel angle sensor 30 is performed by the yaw rate sensor 36.
It is good also as composition which performs using. For example, VH / ΔY <B
Diagnosis is made with (set value) (where VH is the steering wheel angular velocity) as a failure condition. Even in this case, the failure condition is satisfied only when the steering wheel angle sensor 30 fails, so that the failure diagnosis can be performed during the execution of the knob position correction.

(T) The failure may be diagnosed immediately when the failure condition is satisfied. (S) A warning light may be displayed to notify the operator of the occurrence of the failure. According to this configuration,
The failure inspection of the tire angle sensor 28 is performed early.

(X) The present invention may be applied for the purpose of correcting the position of a handle without a knob. (Y) The present invention can be widely applied to industrial vehicles other than forklifts equipped with a power steering device, and also to vehicles such as automobiles (passenger cars).

The technical ideas (inventions) grasped from the above embodiments and not described in the claims are described below together with their effects. (A) In claim 1, the detector to be subjected to failure diagnosis by the failure diagnosis means is a steering angle detector, and the failure diagnosis means uses a steering angle detector to determine a change in the rate of change in the direction of the vehicle. When the detected change in the turning angle is smaller than a predetermined value which can be regarded as a failure, the failure of the steering angle detector is diagnosed. According to this configuration, a failure of the steering angle detector can be found. Not only falling out failures but also failures that are about to fall out can be found.

(B) In any one of the first to ninth aspects, the control means may be configured to calculate a steering angle based on a steering angle detected by the steering angle detector and a steering angle detected by the steering angle detector. The correcting means is driven so as to eliminate a deviation in the handle relative angle from the determined target handle angle. According to this configuration, since only the deviation in the relative angle of the handle is considered as a problem and the correction is performed, even if the deviation is one rotation or more, for example, only a correction amount for a fraction smaller by one rotation is required.

(C) In the invention of (b), the control means controls the correction means only when the steering wheel is operated in a direction requiring a small amount of rotation from the steering wheel angle to the target steering wheel angle. Drive. According to this configuration, even when the displacement of the steering wheel is less than one rotation and exceeds 180 degrees, the correction of shifting by one rotation always requires a correction amount of less than 180 degrees. In addition, the shift can always be reduced when the correction is performed.

(D) Claims 1 to 9 and (a)
In any one of (c) to (c), the driving unit is driven by a hydraulic oil supply unit that discharges an oil amount according to an operation amount of the handle, and is driven by hydraulic oil discharged from the hydraulic oil supply unit. An actuator for steering the steered wheels, wherein the correction means is driven to open such that a part of the oil amount discharged from the hydraulic oil supply means is recirculated before being supplied to the actuator. Valve means is provided. According to this configuration, the same effect as the invention according to any one of claims 1 to 9 and (a) to (c) can be obtained. The orbit roll 4 constitutes a hydraulic oil supply unit, and the steering cylinder 12 constitutes an actuator.

(E) Claims 1 to 9 and (A)
In any one of (a) to (d), the control unit controls the correction unit such that a knob of the handle is arranged at a proper position. According to this configuration, the position of the knob can be corrected to a regular position corresponding to the turning angle of the steered wheel, and the position of the knob can be used as a guide for determining the turning angle of the steered wheel.

(F) In the invention described in claim 9, the vehicle is an industrial vehicle. According to this configuration, the failure of the detector of the industrial vehicle which is easily exposed to the severe vibration can be diagnosed, and other effects similar to those of the ninth aspect can be obtained.

[0102]

As described in detail above, according to the first and ninth aspects of the present invention, a turning detector for outputting a detection value capable of measuring a change in the direction of the vehicle is provided, and the deviation of the steering wheel is reduced. A failure of the detector provided for the detection is diagnosed based on a fact that a change in the detected value is smaller than a predetermined value which can be regarded as a failure in comparison with a change in the rate of change in the direction of the vehicle, so that the displacement of the steering wheel is determined. The fault diagnosis can be performed even during the execution of the correction.

According to the second and ninth aspects of the invention, the change rate of the direction of the vehicle is changed,
Since a failure is determined when the detection value of the failure diagnosis target detector takes a constant value, a failure such as a dropout failure in which the detection value of the failure diagnosis target detector is fixed to a constant value within a normal range can be found. .

According to the third and ninth aspects of the present invention, the failure diagnosis is performed when the vehicle speed is equal to or higher than the predetermined vehicle speed.
The accuracy of failure diagnosis can be improved. According to the fourth and ninth aspects of the present invention, a failure occurs when the failure diagnosis condition is continuously satisfied for a predetermined period of time. Therefore, an erroneous diagnosis resulting from a transiently inappropriate detection value is taken. Can be suppressed as much as possible.

According to the fifth and ninth aspects of the present invention, if the failure diagnosis condition is not satisfied, the diagnosis result of the failure is canceled. It is restarted.

According to the sixth and ninth aspects of the invention, the steering angle detector which is provided near the steered wheels and is relatively susceptible to a failure due to vibration from the road surface is set as a failure diagnosis target. The trouble caused by the failure of the detector for detecting the displacement can be effectively avoided.

According to the seventh and ninth aspects of the present invention, since the yaw rate detector which outputs the detected value corresponding to the change rate of the direction of the vehicle relatively reliably is used as the turning detector, The diagnostic processing can be simplified, and the accuracy of the failure diagnosis can be further increased.

According to the eighth and ninth aspects of the present invention, the yaw rate detector provided in the vehicle for controlling the vehicle body swing is used for the failure diagnosis. You don't have to.

[Brief description of the drawings]

FIG. 1 is a schematic view of a power steering device according to an embodiment.

FIG. 2 is an electric configuration block diagram of a steering wheel angle correction device.

FIG. 3 is a time chart of an output signal from an encoder.

FIG. 4 is a map diagram for obtaining a target steering wheel angle from a tire turning angle.

FIG. 5 is an explanatory diagram of knob position correction control.

FIG. 6 is a flowchart of a sensor failure diagnosis process.

FIG. 7 is a flowchart of a knob position correction control process.

FIG. 8 is a flowchart of an interrupt routine.

FIG. 9 is a schematic view of a steering device according to the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Power steering device, 2 ... Steering wheel, 2a ... Knob, 4 ... Orbit roll which comprises a drive means, 12 ...
Steering cylinder constituting drive means, 19 ... Steered wheels, 22 ... Electromagnetic switching valve as correction means, 27 ... Rotary encoder as steering wheel angle detector, 28 ... Tire angle sensor as steering angle detection means, 35 ... Vehicle speed detection Vehicle speed sensor as means, 36 ... Yaw rate sensor as turning detector and yaw rate detector, 43 ... Excitation / demagnetization drive circuit as control means, 44 ... CPU as control means and failure diagnosis means, 45 ... ROM , 49 ...
An error counter constituting a failure diagnosis means, F: forklift as a vehicle, θ: steering wheel angle, R: tire turning angle as turning angle, δ: deviation amount.

Claims (9)

[Claims] 1. A steering wheel angle detector for detecting a steering wheel angle of a steering wheel, a steering angle detector for detecting a steering angle of a steering wheel, and a driving means for steering a steering wheel according to an operation amount of the steering wheel. And a correction means for correcting the steering wheel turning angle change ratio with respect to the steering wheel operation amount so as to create an idling state of the steering wheel operation, and a detection value necessary for measuring a change in the direction of the turning of the vehicle. A turning detector to output, a rate of change in the direction of the vehicle from the detected value of the turning detector, and a failure rate of at least one of the steering wheel angle detector and the steering angle detector; Failure diagnosis means for making a diagnosis based on the fact that the change in the detection value of the detector to be diagnosed is smaller than a predetermined value that can be regarded as a failure, and a deviation in the correspondence between the steering wheel angle and the steering angle. Inspection Control is performed to drive the correction means when the steering wheel is operated in a direction to reduce the deviation, and when the failure diagnosis target is diagnosed as a failure by the failure diagnosis means, the correction means is driven. A steering angle correction device in a power steering device, comprising: 2. The failure diagnosis unit according to claim 1, wherein the detection value of the detector to be subjected to the failure diagnosis is constant even though the change rate of the direction of the vehicle measured from the detection value of the turning detector changes. 2. The steering wheel angle correction device in a power steering device according to claim 1, wherein the device is diagnosed as having a failure. 3. The vehicle according to claim 1, further comprising a vehicle speed detecting means for detecting a vehicle speed, wherein the failure diagnosing means performs a failure diagnosis when the vehicle speed detected by the vehicle speed detecting means is equal to or higher than a predetermined speed. Item 3. A steering angle correction device in the power steering device according to Item 2. 4. The failure diagnosis means according to claim 1, wherein a change in a detection value of said detector as a failure diagnosis target is less than said predetermined value, based on a change in a change rate of a direction of the vehicle measured from a detection value of said turn detector. The steering angle correction device for a power steering device according to any one of claims 1 to 3, wherein a failure is diagnosed when a failure diagnosis condition that becomes smaller is continuously satisfied for a predetermined time. 5. The failure diagnosis device according to claim 1, wherein the failure diagnosis unit cancels the failure diagnosis result when the failure diagnosis condition based on which the failure is diagnosed is not satisfied after the failure diagnosis. A steering angle correction device in the power steering device according to any one of the preceding claims. 6. The detector to be subjected to a failure diagnosis for which the failure diagnosis means performs a failure diagnosis is the steering angle detector.
A steering angle correction device for a power steering device according to any one of claims 1 to 5. 7. The steering wheel angle correction device for a power steering device according to claim 1, wherein the turning detector is a yaw rate detector that detects a yaw rate of the vehicle. 8. A vehicle body for restricting swinging of steerable wheels that can swing on the vehicle body when the lateral G of the vehicle obtained from the product of the yaw rate of the vehicle and the vehicle speed takes a value equal to or greater than a predetermined value. The steering angle correction device for a power steering device according to claim 7, wherein the steering angle correction device is provided in the vehicle for detecting a detected value of a yaw rate used for calculating the lateral G for the swing regulation control. 9. A vehicle comprising the steering wheel angle correction device according to claim 1. Description: