JPH10119797A - Steering wheel angle correcting device in power steering device and vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure necessary play for a steering wheel even in case of providing a hydraulic power steering. SOLUTION: A map M1 is provided to obtain a target steering wheel angle θg for correcting a steering wheel angle θ (actual position of a steering wheel), detected from a steering wheel relative angle by a potentiometer to which the rotation of the steering wheel (knob) is inputted, into a normal position on the basis of the steering wheel relative angle from a tire steering angle (t) detected by a potentiometer to which the rotation of a king pin of a dirigible road wheel is inputted. A control target line L set to the map M1 is so set that a moving locus in the relation between the actual position of the steering handle (knob) and the tire steering angle (t) forms such a hysteresis loop H1 as to lead to idling of a play part at the time of reverse operation of the handle (knob) in a rectilinear range (-R<=t<=R) allowable to the steered angle of the dirigible road wheel during rectilinear travel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steering wheel angle correcting device for a power steering for correcting a positional difference between a steering wheel angle and a steering wheel turning angle in a vehicle such as a forklift equipped with a power steering device. is there.

[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. For this reason, the position of the knob may be used as a guide for determining whether or not the turning angle of the steered wheels is in the straight traveling posture. However, the amount of oil discharged in accordance with the operation amount of the steering wheel is not always used for driving the steering cylinder. When the roll efficiency (actual discharge amount / theoretical discharge amount) is reduced, a deviation occurs in the positional relationship 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 51
Are a steering unit 53 operated by a handle 52, a steering cylinder 54 for steering a steered wheel (not shown), and hydraulic lines 55 and 56 connecting the steering unit 53 and the steering cylinder 54.
And One of the hydraulic lines 55 and 56 has a steering pump 5 corresponding to the steering direction of the steering wheel 52.
7 serves as a feed line for feeding the pressurized hydraulic oil, and the other line serves as a return line for returning the oil to the hydraulic oil tank 58. An electromagnetic switching valve 60 is provided in the drain oil line 59 connecting the two hydraulic lines 55 and 56.

The control means 61 receives a handlebar rotation angle signal θabs from a handlebar rotation angle sensor 62 and a cylinder stroke signal s from a cylinder position sensor 63. The control means 61 calculates the target tire turning angle tg from the steering wheel rotation angle signal θabs using a map M as shown in FIG.
And the actual tire turning angle t determined from the signal value s
When the deviation from the target tire turning angle tg exceeds an allowable value, the solenoid 64 is excited to open the electromagnetic switching valve 60.

When the electromagnetic switching valve 60 is opened,
A part of the hydraulic oil in the feed line among the hydraulic lines 55 and 56 flows through the drain oil line 59 to the other return line, and flows out (recirculates) to the hydraulic oil tank 58. as a result,
The operation of the steering wheel idles, and the position of the handle 52 is corrected by the idle rotation.

[0008]

However, in the case of a fully hydraulic steering system, it takes only a few degrees (about 2 to 3 degrees) from when the steering wheel 52 is turned until the valve of the steering unit 53 is opened. As shown in FIG. 8, the actual position of the handle 52 moves so as to form a hysteresis loop Hx as shown in FIG. It was like. The angle amount of the delay in the reaction of the valve is the play amount of the handle 52.
The play of 2 was very small compared to the mechanical steering device.

During straight running, the steering wheel 52 is operated left and right near the neutral position for fine adjustment of the steering angle of the steered wheels. However, since the play of the steering wheel 52 is very small, there is a problem that the steering angle of the steered wheels is sensitively operated even if the steering wheel 52 is operated with the play. Therefore, it has been desired that the play of the handle 52 be made comparable to that of a mechanical steering device.

[0010] The present invention has been made in view of the above problems, and a first object of the present invention is to provide a power steering system capable of ensuring a necessary play in a steering wheel even if a hydraulic power steering system is provided. It is an object of the present invention to provide a steering wheel angle correction device in a steering device and a vehicle. A second object is to improve the convergence of the steering wheel to a neutral position when the steered wheels are returned to the straight traveling posture.

[0011]

According to the first aspect of the present invention, there is provided a driving means for steering a steered wheel in accordance with an operating position of a steering wheel, and an actual position of the steering wheel. Steering angle detecting means for detecting the steering angle, steering angle detecting means for detecting the steering angle of the steered wheels, target value calculating means for obtaining a correction control target value from the steering angle, and the driving means for the operation amount of the steering wheel Correcting means for reducing the ratio of the change amount of the driving amount to create the idling state of the steering wheel; and the correcting means so that the deviation between the detected value of the actual position of the steering wheel and the correction control target value falls within an allowable range. Control means for driving and controlling the correction means, wherein the correction control target value obtained by the target value calculation means is at least in a straight traveling range in which the steered wheels have a posture in straight traveling. The shift amount capable of idling by a predetermined amount the handle during inversion of the dollar operation is set to occur.

According to a second aspect of the present invention, in the steering angle correction device for the power steering device according to the first aspect, the correction control target value is obtained by correcting the actual position of the steering wheel by performing a correction when the steering operation is reversed. The movement trajectory in relation to the turning angle is set so as to draw a hysteresis loop.

According to a third aspect of the present invention, in order to achieve the second object, in the steering wheel angle correcting apparatus according to the first or second aspect, the correction control target value is determined only when the steering wheel is operated in the straight traveling range. The actual position of the steering wheel operated toward the neutral position so that the actual position is along the set value of the correction control target value outside the straight traveling range is set to the straight traveling. The idle rotation of the handle when entering the range is set so that the actual position can approach the neutral position.

According to a fourth aspect of the present invention, in the steering wheel angle correcting apparatus according to any one of the first to third aspects, the correction control target value is set to a value common to the steering wheel operating direction. ing.

According to a fifth aspect of the present invention, in the steering wheel angle correcting apparatus according to any one of the first to third aspects, the correction control target value is determined by operating the steering wheel with respect to the steering angle. Different values are set for each direction.

According to a sixth aspect of the present invention, in the steering wheel angle correcting apparatus according to any one of the first to fifth aspects, the target value calculating means stores the correction control target value in the steering angle. Storage means for storing a map to be obtained from.

According to a seventh aspect of the present invention, the vehicle is provided with the steering wheel angle correcting device according to any one of the first to sixth aspects. (Operation) According to the first aspect of the present invention, the steered wheels are steered by the driving means in accordance with the operation of the steering wheel. The actual position of the steering wheel is detected by the steering wheel angle detecting means, and the steering angle of the steered wheels is detected by the steering angle detecting means, and the correction control target value is obtained from the steering angle by the target value calculating means. Then, the control means drives and controls the correction means so that the deviation between the detected value of the actual position of the steering wheel and the correction control target value falls within an allowable range. The actual position of the handle is corrected to a normal position by driving the correction means and reducing the rate of change of the drive amount of the drive means with respect to the operation amount of the handle and causing the handle to idle. At least in the straight traveling range where the steered wheels are in the straight traveling posture, the correction control target value is set so that the steering wheel is rotated by a predetermined amount when the steering operation is reversed. At the handle can play.

According to the second aspect of the invention, the correction based on the amount of deviation from the correction control target value when the steering operation is reversed causes the movement locus in relation to the turning angle of the actual position of the steering wheel to form a hysteresis loop. Since the drawing is performed, the handle can be idle at least in the operation of the steering wheel when traveling straight.

According to the third aspect of the present invention, when the steering wheel is operated toward the neutral position so that the actual position follows the set value outside the straight traveling range of the correction control target value, the steering angle of the steered wheels is reduced. The steering wheel idles based on the deviation between the actual position when entering the straight traveling range and the correction control target value, and the actual position of the steering wheel approaches the neutral position earlier. Therefore, the variation from the neutral position of the steering wheel due to the variation in the turning angle when the steered wheels are returned to the straight traveling posture is relatively small.

According to the fourth aspect of the present invention, since the correction control target value is a value common to the steering wheel operating direction, the load required by the target value calculation means for obtaining the correction control target value can be reduced.

According to the fifth aspect of the present invention, the correction control target value is set to a different value for each steering direction of the steering wheel with respect to the steering angle, so that the steering wheel play at the time of reversing the steering wheel operation is constant. It is possible to set such a correction control target value. In addition, when the correction control target value for each steering wheel operation direction is set over the entire steering wheel operation range, the necessary play can be performed on the steering wheel regardless of where the steering wheel is turned within the steering wheel operation range.

According to the sixth aspect of the present invention, the correction control target value is obtained from the turning angle by the target value calculation means using the map stored in the storage means. According to the seventh aspect of the present invention, the vehicle is provided with the steering wheel angle correction device according to any one of the first to sixth aspects. The same operation as that of the invention described in any one of 6 is obtained.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 2 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. The steering shaft 3 supporting the handle 2 is an orbit roll 4
It is connected to.

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 supplies an oil amount proportional to the rotation amount of the handle 2 to a steering cylinder 12 described later.
It has the function of supplying to Valve unit 5
And the steering cylinder 12 have two hydraulic lines 13,
14 are connected. When the handle 2 is turned to the right, the hydraulic line 13 functions as a supply line for supplying hydraulic oil from the hydraulic pump 6, and the hydraulic line 14 functions as a return line for returning hydraulic oil to the hydraulic pump 6. When the handlebar 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 includes 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. 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 position of the steering wheel 2 is corrected by causing the steering wheel angle to catch up with the steering angle (steering angle) of the steered wheels 19 by idling of the steering wheel 2.

The electromagnetic switching valve 22 is a two-position switching valve,
Shut-off position where the bypass line 21 is cut off (state in FIG. 2)
And a communication position at which the bypass line 21 is communicated. A spool (not shown) constituting the electromagnetic switching valve 22 is urged toward a shut-off position by a spring 24. The electromagnetic switching valve 22 is disposed at a communication position when the solenoid 25 is excited, and the solenoid 25 is demagnetized. When it is done, it will be placed in the blocking position. The solenoid 25 is electrically connected to the controller 26, and is controlled to excite and demagnetize based on a control signal from the 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 controller 26 is electrically connected to a potentiometer 27 as steering angle detecting means and a potentiometer 28 as steering angle detecting means. The potentiometer 27 is a gear train 2 provided on the steering shaft 3.
9 so that the rotation of the steering shaft 3 is input to the input shaft. The gear ratio of the gear train 29 is set to “1.0”, and the potentiometer 2
7, a steering wheel angle signal θ corresponding to the relative angle of the steering wheel 2 is input to the controller 26.

The potentiometer 28 is provided on a king pin 20 that supports the right steering wheel 19, and detects the turning amount of the king pin 20 to detect the steering wheel 19.
Is detected, and a titer angle signal t corresponding to the angle is output to the controller 26.

The potentiometer 27 detects the current position of the knob 2a as a steering wheel angle θ.
The position of the knob 2a when the handle 2 is in the neutral position (the normal handle position when the steering angle is 0 °) is the handle angle θ.
Is set to be “0 °”. In general, in a potentiometer, a non-detection region in which position detection is not possible can always be made in one rotation range of the input shaft (in this embodiment, a detection range of 300 ° is used, for example). By setting so that “0 °” is detected, interruption of the knob position correction near the neutral position of the handle 2 is prevented as much as possible. Since the potentiometer 28 uses only the detectable region for detecting the tire turning angle, the tire turning angle is detected in the entire steering angle range.

The controller 26 constitutes a control means, a target value calculating means and an operation direction detecting means, and has a central processing unit (CPU) 30 as a determining means, a target direction detecting means and a correction execution selecting means, and a target value calculating means. Read-only memory (ROM) configured and as storage means
31, a read / write rewritable memory (RAM) 32, a clock circuit 33, a counter 3 constituting an operation direction detecting means
4, an AD conversion circuit 35, 36 and an excitation / demagnetization drive circuit 37 constituting a control means. Potentiometer 2
The signals θ and t from the signals 7 and 28 are converted to AD conversion circuits 35 and 36, respectively.
As 8-bit AD value (0-255) via CPU
The CPU 30 receives the AD values of the signals θ and t as the steering wheel angle θ and the tire turning angle t.

Various kinds of program data to be executed by the CPU 30 are stored in the ROM 31, and one of them is program data for a knob position correction control process. The ROM 31 stores a map M1 shown in FIGS. 1 and 6 (however, only a part is shown in FIG. 1). Map M
Numeral 1 is for obtaining a target steering wheel angle θg as a correction control target value which is a target position for correcting the position of the knob 2a from the tire turning angle t. Tire cut angle "0
° is associated with the AD value “128”, and if the value of the tire turning angle t is “negative” (AD value ≦ 127), the left turning angle (left steering) and “positive” (AD value ≧ 129) ) Is recognized as a right turning angle (right steering). Target steering wheel angle θ
g is a neutral position (= 0 °) which is a detection area of the steering wheel angle θ.
(AD value = 128)) from the left and right, respectively, “-150 ° to 15
0 ° ”. In the map M1, a control target line L that associates the tire turning angle t with the target steering wheel angle θg is set over the entire turning angle. The target steering wheel angle θg is “−150 °” in the map M1.
The part where the control target line L becomes flat at (AD value = 0) is a non-detection area where the target steering wheel angle θg is not set, and one of the steering wheel angle θ and the tire turning angle t is not detected. When in the area, the knob position correction is not executed.

The control target line L is basically an ideal control line on the assumption that the orbit roll efficiency (actual discharge amount / theoretical discharge amount) is 100%. However, a straight traveling range -R≤t≤R (for example, R
= 1 °), the control target line L is below the ideal control line Lo (broken line) in the region where the tire turning angle t is “positive” and the tire turning angle t is “negative” as shown in FIG. Is shifted upward in the region of. That is, the steering wheel 2 is set to idle by a predetermined amount when the steering operation is reversed in the straight traveling range, and the steering wheel 2 in the straight traveling range is set.
, The movement locus of the actual position (circle) of the knob 2a in relation to the tire turning angle t is set so as to draw a hysteresis loop H1 as shown in FIG. In the present embodiment, the control target line L with respect to the ideal control line Lo is controlled so that the amount of idling of the steering wheel 2 in the reversing operation in the straight traveling range is substantially equal to the amount of play of the steering wheel in a generally distributed mechanical steering device. Is set.

The RAM 32 temporarily stores the calculation results of the CPU 30 and the like. Further, the CPU 30 includes a clock circuit 33.
The predetermined time to (for example, 10
The knob position correction control process is executed at intervals of (milliseconds), and the steering wheel angle θ is set in the counter 34 each time the process is executed. The counter 34 stores data of the handle angle θ for a plurality of times in the past. In addition, a control signal for exciting / demagnetizing the solenoid 25 is output from the CPU 30 via the exciting / demagnetizing drive circuit 37.

In the knob position correction control process, the CPU 30 calculates a deviation amount Δθ between the steering wheel angle θ and the target steering wheel angle θg obtained from the tire turning angle t, so that the deviation amount Δθ falls within the allowable value θo or less. Execute knob position correction.
The shift amount Δθ here means a shift amount of the current knob position and the target knob position along the shortest path as shown in FIGS. 3 and 4, and the actual shift amount Δθs of the knob 2a exceeds 180 °. In this case, the deviation amount Δθ becomes “360 ° −Δθs”.

As shown in FIGS. 3 and 4, the conditions for executing the knob position correction differ depending on whether or not the deviation amount Δθ is equal to or smaller than the predetermined angle A °. That is, as shown in FIG. 3, when the shift amount Δθ is equal to or smaller than A ° (that is, when the actual shift amount Δθs is Δ
θs ≦ A ° or Δθs ≧ (360-A) °) when the operating direction of the handle 2 coincides with the direction from the current knob position to the target knob position via the shortest path (hereinafter referred to as the target direction). As long as the knob position correction is performed. In addition, as shown in FIG.
(That is, if the actual deviation Δθs is A ° <Δ
When θs <(360−A) ° is satisfied), the knob position correction is always executed regardless of the handle operation direction.

Here, the predetermined value A is such that when the deviation amount Δ has increased to some extent, there is a probability that the execution of the correction will decrease rather than increase the deviation amount even if the steering direction is opposite to the target direction. It is a higher boundary value. In this embodiment, the predetermined value A ° is set, for example, to a value in the range of 80 ° to 120 ° to realize effective correction.

The operation direction of the steering wheel 2 is determined by comparing the steering angle θ1 read from the counter 34 a predetermined time n · to before the steering wheel angle θ1 with the current steering wheel angle θ, and | θ−θ1 | ≧ θB
Is determined on the basis of the two determination results of determining whether or not. Here, the θB value is determined by moving the steering wheel 2 for a predetermined time n ·
When the operation amount of the handle 2 (= | θ−θ1 |) is equal to or more than the θB value when the predetermined value is equal to or larger than the physically inoperable limit value within to, the vehicle passes through the non-detection region of the handle angle θ (That is, the AD value is “0”)
And "255"), the operation direction of the steering wheel 2 is determined.

That is, if the value of the steering wheel angle θ has increased during the predetermined time n · to (θ> θ1), the steering direction becomes |
If θ−θ1 | ≧ θB is “not satisfied”, “rightward”,
If “established”, it is determined to be “leftward”. If the value of the steering wheel angle θ has decreased during the predetermined time n · to (θ <θ1), the steering direction is “left” if | θ−θ1 | ≧ θB is “not established”, If "established", "rightward"
Is determined. When θ = θ1, it is determined that the steering operation is stopped.

For the target direction, a comparison is made between the current handle angle θ and the target handle angle θg to determine which of the left and right directions is the shortest path from the current knob position to the target knob position. Is determined. Deviation | θ−θg |
Is 180 ° or less, the target direction is “rightward” when θ <θg holds, and “leftward” when θ> θg holds. If the deviation | θ−θg | exceeds 180 °, the target direction is “leftward” when θ <θg holds, and θ>
It becomes “rightward” when θg is satisfied.

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 handle 2, an oil amount corresponding to the operation amount of the handle 2 is discharged from the valve unit 5. Then, the operating oil discharged from the valve unit 5 is supplied to the steering cylinder 12, so that the steered wheels 19 are steered to a steering angle corresponding to the operating position of the steering wheel 2. If the knob 2a deviates from the normal position due to a decrease in the orbit roll efficiency when the steering wheel operating speed is low or an oil leak in the hydraulic system such as the steering cylinder 12, the position of the knob 2a is changed to the tire turning angle. Knob position correction control is performed to correct the position to a proper position corresponding to.

Hereinafter, the knob position correction control executed by the CPU 30 will be described. While the engine of the forklift F is being driven, the CPU 30 sends a signal from the potentiometer 27 to the knob 2.
A steering wheel angle signal θ corresponding to the relative angle of “a” and a tire turning angle signal t corresponding to the turning angle of the steered wheel 19 from the potentiometer 28 are input through the AD conversion circuits 35 and 36.

The CPU 30 reads the steering wheel angle θ and the tire turning angle t, and obtains the target steering wheel angle θg from the current tire turning angle t using a map M1 shown in FIG. Then, the shift amount Δθ (shift amount in the shortest path) between the current knob position and the target knob position is calculated. If the deviation Δθ exceeds the allowable value θo, the knob position correction is executed during the operation of the steering wheel when a predetermined correction execution condition is satisfied.

In order to determine whether the correction execution condition is satisfied, the deviation amount Δ
It is determined whether or not θ is greater than a predetermined value A °, whether or not the steering operation is stopped, and the determination of the steering operation direction and the target direction. The steering direction of the steering wheel is determined by comparing the steering angle θ1 read from the counter 34 a predetermined time n · to before the steering wheel angle θ1 with the current steering wheel angle θ, and
It is determined whether or not | ≧ θB is satisfied, and the determination is made based on the two determination results. The determination as to whether or not the steering operation is stopped is made in the magnitude comparison processing between θ and θ1, and if the steering operation is being performed, the operating direction is obtained. The target direction is determined as a direction that requires the shortest path from the current knob position to the target knob position, based on a comparison between the current handle angle θ and the target handle angle θg.

When the deviation Δθ is equal to or less than a predetermined value A °,
As shown in FIG. 3, when the knob 2a is located at the solid line position, the knob 2a approaches the target knob position via the shortest path.
The knob position correction is executed only when the steering wheel is operated in the direction, and the knob position correction is not executed when the knob 2a is operated in the x1 direction away from the target knob position (that is, approaching the longest path). When the knob 2a is located at the chain line position, the knob position correction is executed only when the steering wheel is operated in the a2 direction, and when the knob is operated in the x2 direction, the knob position correction is not executed. At this time, since the deviation amount Δθ in the shortest path becomes the correction amount instead of the actual deviation amount Δθs, (3)
60-A) Even if it is shifted by more than °, the correction amount only needs to be Δθ of less than 180 °. For example, the actual deviation amount Δθs is 280 °
However, a correction amount of 80 ° is sufficient. Note that no matter how much the actual knob position deviates from the normal position corresponding to the tire turning angle by 360 ° or more, the correction amount is always less than 360 °.

On the other hand, as shown in FIG. 4, when the deviation amount Δθ exceeds a predetermined value A °, the operation direction of the steering wheel 2 is either left (b direction) or right (c direction). Whenever the steering wheel is operated, the knob position correction is executed. When the steering operation is performed in the direction c, the correction is performed along the longest route. However, in a region where the deviation amount Δθ exceeds the predetermined value A °, the probability of reducing the position deviation amount of the knob 2a is higher than increasing the deviation amount. Therefore, the number of opportunities for knob position correction increases, and it is possible to avoid leaving a large displacement exceeding A ° as much as possible.

Next, the correction of the knob position when the steering wheel 2 is traveling straight ahead and the knob position correction when returning the steering wheel 2 to the neutral position will be described. First, the knob position correction when returning the handle 2 to the neutral position after turning will be described. A case where the steering wheel 2 is turned right and then returned to the neutral position will be described as an example.

After turning right, the steering wheel 2 is turned back.
It is assumed that when the vehicle is turned left toward the neutral position, the knob 2a moves along a locus along the control target line L (coincides with the line Lo because it is outside the straight traveling range). In FIG. 1, when the vehicle enters the straight traveling range and the actual position of the knob 2a reaches the point B1, the deviation amount Δθ exceeds the allowable value θo, and the steering direction at this time coincides with the target direction. The electromagnetic switching valve 22 is opened.
As a result, the handle 2 idles until the actual position of the knob 2a follows the path of the hysteresis loop H1 from the point B1 to reach the target steering wheel angle θg on the control target line L, and the idle rotation advances the actual position of the knob 2a. Approach the neutral position. For this reason, even if the steering angle when the steered wheels 19 are returned to the straight traveling posture slightly varies in the range of 0 ≦ t ≦ R, the variation of the actual position of the knob 2a from the neutral position becomes relatively small. Similarly, when returning the steering wheel 2 that has been turned left to the neutral position, the steering wheel 19 is idled so that the actual position, which has entered the straight traveling range, approaches the neutral position as soon as possible. The variation of the actual position of the knob 2a from the neutral position when it is returned to is relatively small.

Therefore, when returning the steering wheel 2 from the right turn to the neutral position, or when returning the handle 2 from the left turn to the neutral position,
Variations in each direction from the neutral position of the knob 2a are relatively small. Therefore, as shown in FIG.
The overall variation B of the actual position of the knob 2a with respect to the neutral position when the steering wheel 2 is returned until the steered wheels 19 assume the straight traveling posture is relatively small as compared with the conventional power steering device. Therefore, the convergence of the knob 2a to the neutral position when the steered wheels 19 are returned to the straight traveling posture is enhanced.

On the other hand, during straight running, the steering wheel 2 is operated right and left around a substantially neutral position within the straight running range (-R≤t≤R). That is, the steering wheel operation is performed such that the steering wheel 2 is repeatedly inverted so as to straddle the neutral position.

For example, it is assumed that the vehicle shifts to straight running after the actual position of the knob 2a reaches the point B1. When the handle 2 is turned to the left from the state where the actual position of the knob 2a is at the point B1, the actual position of the knob 2a moves so as to follow the path h1 of the hysteresis loop H1. It becomes play. Thereafter, when the steering wheel 2 is turned to the left at a tire turning angle t near -R °, the steering wheel 2 moves to the point B2 along the route h1 while maintaining the advance amount of the play. Next, from the state where the actual position of the knob 2a is at the point B2, the handle 2
Is turned rightward, the actual position of the knob 2a moves so as to follow the path h2 of the hysteresis loop H1.
Slightly slips by the amount of the play, and then moves along the route h2 to, for example, point B3 while maintaining the advance amount of the play. When the handle 2 is turned again when the knob position reaches the point B3, the handle 2 can play at the time of the turn because the handle 2 follows the path h1 again.

Thus, when the steering wheel 2 is operated for fine adjustment while traveling straight, the steering wheel 2 can idle due to idling every time the operation is reversed. Therefore, even with the hydraulic power steering device 1, the handle 2 can have the same play as the mechanical steering device. Therefore, when the handle 2 is moved for play,
Since the steering angle of the steered wheels 19 does not react, the steering wheel can be operated with the same operation feeling as that of a mechanical steering device. In addition, in the straight range,
Although the actual position of the knob 2a differs on the path h1 and h2 depending on the operation direction of the handle 2, there is no problem because the deviation is within the allowable range. When the values of θ and θg are out of the detection range, the knob position correction is interrupted. However, since the interruption of the correction is temporary while passing through the non-detection region, there is not much problem.

As described in detail above, according to the present embodiment,
The following effects can be obtained. (A) The control target line L is set so that the actual position of the knob 2a draws a hysteresis loop H1 in relation to the tire turning angle t when the steering wheel 2 is operated left and right for fine adjustment during straight running. Since the electromagnetic switching valve 22 is opened at the time of the reversal of 2 so that the required amount of play can be provided to the handle 2, it is possible to prevent the steering wheel 19 from reacting sensitively when the handle is operated with the intention of play. it can.

(B) The formation area of the hysteresis loop H1 is limited to the straight traveling range, and when the steering wheel 2 is operated toward the neutral position, the actual position of the knob 2a is set shortly before the steered wheels 19 reach the straight traveling posture. Since the idle rotation of the steering wheel 2 is quickly performed to approach the neutral position, the convergence of the knob 2a to the neutral position when the steered wheels 19 are returned to the straight traveling posture can be enhanced.

(C) Since the hysteresis loop H1 is such that the ideal control line Lo passes through the center, the deviation of the actual position of the knob 2a from the normal position due to the difference in the operating direction of the handle 2 can be relatively determined. Can be made smaller.

(D) Since the hysteresis loop H1 is formed by one control target line L common to the steering wheel operating direction, only one map M1 for obtaining the target steering wheel angle θg is required. The load on the CPU 30 for calculating the angle θg can be reduced as much as possible.

(E) Since the map M1 is used to determine the target steering wheel angle θg from the tire turning angle t, the load on the CPU 30 for calculating the target steering wheel angle θg can be reduced.

(F) Since the target steering wheel angle θg is determined by the steering wheel relative angle based on the tire turning angle, and the knob position correction for correcting the deviation amount at the steering wheel relative angle is employed, the actual deviation amount Δθs becomes 360. ° or more
It is possible to always use a correction amount smaller than 360 °, which is smaller by one or two rotations than the actual deviation amount Δθs.

(G) When the shift amount Δθ is equal to or smaller than A °, the correction is executed only when the steering wheel 2 is operated in the target direction passing through the shortest path, so that the actual shift angle amount is, for example, 280 °. Even if there is, a correction amount of about 80 ° can be completed.

The present invention is not limited to the above embodiment, but can be embodied as follows without departing from the spirit of the invention. (1) A hysteresis loop may be formed by setting the line of the correction control target value to a different value for each operation direction of the steering wheel. For example, as shown in a map M2 shown in FIG. 7, control target lines L1 and L2 parallel to each other are set for each steering wheel operation direction so that a hysteresis loop H2 is formed at least in a straight traveling range (−R ≦ t ≦ R). I do. According to this configuration, the amount of play when the steering wheel 2 is inverted when traveling straight ahead can be kept constant regardless of the inverted position of the steering wheel 2. Also, only in the straight traveling range, the two control target lines L1, L2
If the steering wheel 19 is returned to the straight traveling posture, the convergence of the knob 2a to the neutral position can be improved. Of course, the tire turning angle t
The control target lines L1 and L2 are set for each steering wheel operation direction over the entire range of the steering wheel 19, so that the steering wheel 2 can always have play regardless of where the steering wheel 19 is turned at the turning angle t of the steering wheel 19. May be.

(2) The amount of play of the steering wheel 2 can be appropriately set as required, and does not necessarily need to be adjusted to the amount of play of the mechanical steering device. (3) The present invention may be adopted only for the purpose of enhancing the convergence of the handle to the neutral position. In this case, the idling amount of the steering wheel when the vehicle reaches the straight traveling range is not limited to the normal play amount of the steering wheel, and can be set to a value that can effectively reduce the variation in the steering wheel position.

(4) The straight traveling range referred to in the present invention refers to an angle range necessary for fine adjustment of the steering angle of the steered wheels during straight traveling, and varies according to the traveling speed of the vehicle. It refers to a range of up to about ± 10 ° in cutting angle t at the maximum. Of course, it is needless to say that a configuration in which the play amount of the handle 2 is secured in an area other than the straight traveling range can be adopted.

(5) A reduction gear having a worm gear or the like is employed between the steering shaft 3 and the potentiometer 27, and the absolute angle detection value detected by the potentiometer 27 is converted into a relative angle by calculation or the like, and the tire turning angle is calculated. The actual steering wheel angle θ may be corrected to the target steering wheel angle θg of the relative angle obtained from t. According to this configuration, although calculation means for obtaining the relative angle θ from the absolute angle is required, even in the configuration in which the steering wheel angle θ is detected using the potentiometer 27, the non-detection region of the steering wheel angle θ is determined. Can be eliminated.

(6) The steering wheel angle θ may be detected by using a rotation detector such as a rotary encoder that detects the rotation of the steering shaft 3 so as to eliminate a non-detection area which cannot be avoided by using the potentiometer 27.

(7) The present invention may be implemented for the purpose of correcting the position of a handle without a knob. By applying the present invention to a handle without a knob, the play required for the handle during straight running can be ensured.

(8) The present invention may be applied to a conventional apparatus for detecting a steering wheel angle based on an absolute angle as described in the prior art. (9) In the above embodiment, the invention is applied to a forklift.
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 invention which has been grasped from the above embodiment and which is not described in the claims will be described below together with its effects. (A) In the invention according to any one of claims 2 to 7, the correction control target value is set such that a line of a control ideal value passes substantially at the center of the hysteresis loop. According to this configuration, a hysteresis loop is formed such that the line of the ideal control value substantially passes through the center, so that variations in the handle position from the normal position due to the difference in the handle operation direction can be reduced.

(B) Claims 1 to 7 and (a)
In the invention described in any one of (1) to (4), the shift amount that allows the handle to idle by a predetermined amount when the handle operation is reversed is a hydraulic oil supply device (orbit roll 4) that discharges an oil amount corresponding to the handle operation amount. ) Is set in consideration of the reaction delay. According to this configuration, the required play amount of the handle can be set accurately. (C) In the invention described in any one of claims 1 to 7 and any one of (a) and (b), the steered wheels operate based on hydraulic oil discharged in accordance with an operation amount of the steering wheel. The switching means is a switching valve provided on a recirculation passage for recirculating a part of the hydraulic oil discharged to the actuator to a drain tank. is there. According to this configuration, the handle can be provided with play when the handle is operated during straight running.

(D) Claims 1 to 7 and (a)
In the invention described in any one of (a) to (c), the handle angle detection means detects an actual position of the handle as a relative angle, and the target value calculation means calculates the correction control target value determined from the turning angle. The control means is configured to drive control the correction means so that the actual position of the steering wheel and the target position match at a relative angle within at least an allowable range. I have. According to this configuration, the steering wheel position is corrected so that the actual position of the steering wheel matches the correction control target value obtained from the steering wheel turning angle based on the steering wheel relative angle at least within the allowable range at the relative angle. Since the position of the steering wheel is corrected using the amount of deviation in the relative angle as the correction amount, even when the steering wheel is displaced by 360 degrees or more with respect to the steered wheels, the correction amount is smaller by one or two rotations and less than 360 degrees. I'm done.

(E) Claims 1 to 7 and (A)
In the invention described in any one of (a) to (d), the control means includes: a target direction detecting means for detecting a target direction in which the handle needs a shortest path from the actual position to the target position; Operation direction detection means for detecting the operation direction of the handle, and correction execution selection means for executing position correction of the handle only when the operation direction of the handle matches the target direction. According to this configuration, the steering wheel position is corrected only when the steering wheel is operated in the target direction where the shortest path is required to reach the target position from the actual position.
Even when the angle is less than 0 °, the correction amount is smaller than the actual deviation amount, and the idling of the handle accompanying the position correction of the handle can be further reduced.

(F) Claims 1 to 7 and (a)
In the invention according to any one of (a) to (e), the handle is provided with a knob, and the control means drives and controls the switching means so that the knob 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.

(G) In the invention described in claim 7, the vehicle is an industrial vehicle. According to this configuration, the same effect as that of the invention described in claim 7 can be obtained in an industrial vehicle.

[0075]

As described in detail above, claims 1 and 2 have been described.
According to the invention described in claim 7, the correction control target value is set such that the steering wheel idles by a predetermined amount when the steering wheel operation is reversed, at least during straight running.
A necessary play can be provided to the steering wheel when the steering wheel is operated straight ahead, and the steering angle of the steered wheels can be prevented from being excessively sensitive to the steering wheel operation.

According to the third and seventh aspects of the present invention, when the handle is returned to the neutral position, the handle idles in the straight traveling range, and the correction is made such that the handle position approaches the neutral position early. , The convergence of the steering wheel to the neutral position when the steered wheels are returned to the straight forward posture can be improved.

According to the fourth and seventh aspects of the present invention, since the correction control target value is set to a common value in the steering wheel operating direction, the load required for the process of obtaining the correction control target value by the target value calculation means. Can be reduced.

According to the fifth and seventh aspects of the present invention, the correction control target value is set to a different value for each steering wheel operating direction with respect to the turning angle, so that a constant play is independent of the inversion position of the steering wheel. The setting of the correction control target value that ensures the above can be realized. Also, when the correction control target value is set for each steering wheel operation direction over the entire steering wheel operation region,
The required play can be ensured regardless of where the handle is inverted in the handle operation area.

According to the present invention, the target value calculating means obtains the correction control target value from the turning angle using the map stored in the storage means, and thus obtains the correction control target value. Calculation processing is simple.

[Brief description of the drawings]

FIG. 1 is a graph showing a part of a map according to an embodiment.

FIG. 2 is a schematic diagram of a power steering device.

FIG. 3 is an explanatory diagram of knob position correction control.

FIG. 4 is an explanatory view of the same.

FIG. 5 is a plan view of a handle.

FIG. 6 is a graph showing a map.

FIG. 7 is a graph showing a part of a map of another example.

FIG. 8 is a graph showing a part of a conventional map.

FIG. 9 is a schematic view of a conventional device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Power steering device, 2 ... Steering wheel, 19 ... Steering wheel, 22 ... Electromagnetic switching valve as a correction means, 27 ... Potentiometer as a steering angle detection means and 28 as steering angle detection means A potentiometer, 30... Constituting a control means, a target value calculating means and an operation direction detecting means and a CPU as a target direction detecting means and a correction execution selecting means, 31...
34, a counter constituting operation direction detecting means, 37, an excitation / demagnetization drive circuit, constituting control means, F, a forklift as a vehicle, θg, a target steering wheel angle as a correction control target value, M1, M2, maps, L, L1, L2: Control target line, H1, H2: Hysteresis loop.

Claims (7)

[Claims] 1. A driving means for steering a steered wheel according to an operating position of a steering wheel, a steering wheel angle detecting means for detecting an actual position of a steering wheel, and a steering angle detecting means for detecting an turning angle of the steering wheel. Target value calculation means for obtaining a correction control target value from the turning angle; and correction means for reducing the ratio of the amount of change in the drive amount of the drive means to the amount of operation of the handle to create the idling state of the handle. And control means for driving and controlling the correction means so that a deviation amount between the detected value of the actual position of the steering wheel and the correction control target value falls within an allowable range, and is obtained by the target value calculation means. The deviation amount at which the correction control target value allows the steering wheel to idle by a predetermined amount when the steering wheel operation is reversed, at least in a straight traveling range in which the steered wheels are in a posture in a straight traveling. Steering wheel angle correction device in a power steering device that is set so as to generate the steering angle. 2. The correction control target value is set such that a movement trajectory in relation to the turning angle of the actual position of the steering wheel forms a hysteresis loop by the correction when the steering operation is reversed. A steering wheel angle correction device in the power steering device according to item 1. 3. The correction control target value is set so that correction by inversion of a steering operation is performed only in the straight traveling range, and the actual position is set to a value outside the straight traveling range of the correction control target value. It is set so that the idle rotation of the handle when the actual position of the handle operated along the neutral position along the straight line enters the straight traveling range can make the actual position approach the neutral position. A steering angle correction device for the power steering device according to claim 1 or 2. 4. The steering wheel angle correction device for a power steering device according to claim 1, wherein the correction control target value is set to a value common to the steering wheel operation direction. 5. The power steering apparatus according to claim 1, wherein the correction control target value is set to a different value with respect to the steering angle for each operation direction of the steering wheel. Steering wheel angle correction device. 6. The target value calculation means according to claim 1, further comprising a storage means for storing a map for obtaining said correction control target value from said turning angle. Steering wheel angle correction device in a power steering device. 7. A vehicle comprising the steering wheel angle correction device according to claim 1. Description: