JPH0939817A - Fully hydraulic power steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve operability and safety by eliminating positional slippage of a steering wheel and steered wheels in a fully hydraulic power steering device. SOLUTION: A cylinder left side end detection switch 17 and a cylinder right side end detection switch 18 are respectively arranged on both of left and right ends of a power cylinder 11, and output of these switches 17, 18 is connected to a controller 19. At the time when a stroke of a cylinder 13 is displaced leftward 13L against a rotational position of a steering wheel 5, if the steering wheel 5 is kept steering leaftward 5L, the cylinder 13 reaches a left stroke end, the cylinder left side end detection switch 17 is switched on, and the controller 19 cuts off an electromagnetic clutch 12 in accordance with an ON signal. When the steering wheel 5 idles and displacement quantity εwith the cylinder 13 is set off and a steering wheel left side end detection switch 15 is switched on, the controller 19 makes the electromagnetic clutch 12 into a connected state again.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an all-hydraulic power steering device used in a vehicle such as a forklift truck, and more particularly to an all-hydraulic power steering device capable of correcting the positional deviation between the steering wheel and the steered wheels. It is about.

[0002]

2. Description of the Related Art A vehicle such as a forklift truck is provided with an all-hydraulic power steering device for facilitating steering operation. The all-hydraulic power steering system has a hydraulic pump, which is a power source, a steering control valve that interlocks with a steering wheel, and an actuator that connects to the steered wheels as main constituent elements, and the steering control valve is located between the hydraulic pump and the actuator. Is installed. The steering control valve adjusts the hydraulic oil discharged from the hydraulic pump and supplied to the actuator according to the steering amount of the steering wheel, and the stroke of the actuator is displaced by the hydraulic oil. Thus, the steered wheels are steered left and right by a certain amount according to the steering amount of the steering wheel.

[0003]

In an all-hydraulic power steering system, the steering wheel rotation position is changed by the leakage of hydraulic oil in the steering control valve and the actuator and the expansion of the rubber hose and resin hose used in the hydraulic line. There may be a positional deviation between the stroke of the actuator, that is, the turning angle of the steered wheels. For this reason, the steering wheel position is not constant with respect to the steering wheel position, which impairs drivability and safety.

Therefore, there arises a technical problem to be solved in order to improve the drivability and safety by eliminating the positional deviation between the steering wheel and the steered wheels in the all-hydraulic power steering device. The present invention aims to solve the problems.

[0005]

DISCLOSURE OF THE INVENTION The present invention has been proposed to solve the above problems, in which a steering control valve interlocking with a steering wheel adjusts hydraulic fluid supplied from a hydraulic pump to an actuator, In the all-hydraulic power steering device that steers the steered wheels according to the steering amount of the steering wheel by displacing the stroke of the actuator, the steering wheel and the steering control valve are formed so that they can be contacted and separated by a clutch. In addition, when the rotational position and steering direction of the steering wheel and the stroke of the actuator are detected by the detection means, the steering wheel rotational position and the actuator stroke are deviated from each other, and in the steering direction of the steering wheel. If the stroke is offset, disengage the clutch. And it provides a fully hydraulic power steering apparatus which is formed so as to.

Here, with reference to the steering direction of the steering wheel,
When the actuator stroke is ahead of the steering wheel rotation position, the clutch connecting the steering wheel and the steering control valve is disengaged. As a result, the steering wheel runs idle, offsetting the deviation from the actuator, and correcting the positional deviation between the steering wheel and the steered wheels.

On the other hand, when the actuator stroke is behind the steering wheel rotation position with respect to the steering direction of the steering wheel, the clutch will not be disengaged.
However, if the driver then turns the steering wheel in the opposite direction, the actuator stroke is ahead of the steering wheel rotation position based on the opposite steering direction. The positional deviation is corrected in the same manner as.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to FIGS. FIG. 1 is a circuit diagram of an all-hydraulic power steering apparatus 1 for a vehicle such as a forklift truck. Reference numeral 2 is a hydraulic pump, and hydraulic fluid discharged from the hydraulic pump 2 is diverted by a flow divider 3 before steering. It is sent to the control valve 4. The steering control valve 4 has a direct mechanical link 6 interlocked with the steering wheel 5,
Further, a hydraulic motor 7 and a spool 8 that interlock with the direct mechanical link 6 are provided inside. A left turning hydraulic line 9 and a right turning hydraulic line 10 extend from the steering control valve 4 to the power cylinder 11, and the left turning hydraulic line 9 is connected to the left turning port 11L of the power cylinder 11, respectively. The right turning hydraulic line 10 is connected to the right turning port 11R of the power cylinder 11.

An electromagnetic clutch 12 is interposed between the steering wheel 5 and the direct mechanical link 6 of the steering control valve 4.
In normal times, the electromagnetic clutch 12 is engaged, and therefore the operation of the handle 5 is transmitted to the direct mechanical link 6 as it is. Therefore, when the steering wheel 5 is steered to the left 5L, the spool 8 is switched from the neutral position 8N to the left turning position 8L in conjunction with the direct mechanical link 6, and the hydraulic motor 7 is tilted. As a result, the hydraulic oil is supplied to the left turning port 11L of the power cylinder 11 through the left turning hydraulic line 9 as a passage, and the power cylinder 11
The cylinder rod 13 is slid to the left 13L according to the steering amount of the handle 5. In accordance with this, the hydraulic oil on the right turning port 11R side of the power cylinder 11 flows back to the tank 14 via the steering control valve 4 using the right turning hydraulic line 10 as a return path. Thus, in association with the sliding movement of the cylinder rod 13, the steered wheels (not shown) move to the left 5 of the handle 5.
It steers to the left according to the amount of steering to L.

Similarly, when the steering wheel 5 is steered to the right 5R, the spool 8 is switched to the right turning position 8R, the hydraulic motor 7 is tilted, and hydraulic oil is transferred to the right turning hydraulic line 10. As the feeding path and the left turning hydraulic line 9 as the return path so that the cylinder rod 13 is moved to the right side 13
Slide to R. Then, the steered wheels are steered to the right in accordance with the steering amount of the steering wheel 5 to the right 5R.

As described above, the all-hydraulic power steering apparatus 1 hydraulically steers the steered wheels by an amount corresponding to the steering amount of the steering wheel 5, but the hydraulic oil is the steering control valve 4 and the power cylinder. There is a leak in 11 and there is a left turning hydraulic line 9 and a right turning hydraulic line 10.
When a flexible member such as rubber or resin forming hydraulic piping such as expands, the steering amount of the handle 5 and the position of the cylinder rod 13, that is, the turning angle of the steered wheels may deviate from each other. is there. In order to detect and correct such positional deviation, the flange 1 on the handle 5 side of the electromagnetic clutch 12
A steering wheel left end detection switch 15 and a steering wheel right end detection switch 16 are provided in 2a,
A cylinder left side end detection switch 17 and a cylinder right side end detection switch 18 are provided on both left and right ends of the power cylinder 11, respectively. The outputs of these switches 15 to 18 are connected to the controller 19, and the outputs of the controller 19 are connected to the handle side flange 12a and the steering control valve side flange 12b of the electromagnetic clutch 12.

2 to 8 are explanatory views of the positional deviation correction procedure by the controller 19, in which the upper latitude line H indicates the rotational position of the handle 5, respectively.
The lower latitude line C indicates the stroke of the cylinder rod 13. Further, the relative positional relationship between the latitude line H and the latitude line C shows the relationship between the former rotational position and the latter stroke when there is no relative deviation between the handle 5 and the cylinder rod 13. That is, when a perpendicular is drawn from an arbitrary point on the latitude line H indicating a certain rotation position of the handle 5, the point where the perpendicular intersects with the latitude line C has no relative deviation. It is the stroke of the cylinder rod 13 with respect to the rotational position. The left end of the latitude line C is the left stroke end C _L of the cylinder rod 13, and the right end is the right stroke end C _R thereof. The points H _L and H _R on the latitude line H, which face the left stroke end C _L and the right stroke end C _{R, respectively} , are the handle 5 when there is no relative deviation between the handle 5 and the cylinder rod 13.
Of the rotation limit of the right and left, below, refers to H _L and handle left end position, the H _R of the handle right end position. As described above, when there is no relative deviation, when the handle 5 is at the handle left end position H _L , the cylinder rod 13 is at the left stroke end C _L and the handle 5 is at the handle right end position H _R. when the cylinder rod 13 is positioned to the right stroke end C _R.

The handlebar left end detection switch 15 is steered when the rotational position of the handlebar 5 reaches the handlebar left end position H _L and when the handlebar 5 is steered to the left outside of the handle left end position H _L. It is formed to turn on at times. Meanwhile, the handle right end detecting switch 16 is ON when and where the handle 5 when the rotational position reaches the handle right end position H _R of the handle 5 is steered to the right outer side than the steering wheel right end position H _R Is formed. Also, ON next time the cylinder left end detection switch 17, wherein the cylinder rod 13 is in the left stroke end C _L,
It said cylinder right end detecting switch 18 is formed so as to be ON when the cylinder rod 13 is to the right stroke end C _R.

As shown by the triangular symbols in FIG. 2, the handle 5 has the neutral position H _N.
Although the cylinder rod 13 deviates from the neutral position C _N toward the left stroke end C _L (deviation amount ε), the driver moves the steering wheel 5 to the neutral position H _N. When fixed, the steered wheels are steered to the left by the deviation amount ε of the cylinder rod 13, so that the vehicle turns left. Therefore, in order to go straight, as shown in FIG. 3, the handle 5 must be tilted to the right 5R by the deviation amount ε so that the cylinder rod 13 comes to the neutral position C _N. The safety is poor.

When the handle 5 is steered to the left 5L as far as it is possible to rotate from this state, as shown in FIG. 4, the handle 5 is in front of the left end position H _{L of the} handle by the deviation amount ε. When the side position is reached, the cylinder rod 13 reaches the left stroke end C _L , so that the handle 5 is limited to the rotation limit in the conventional case.
However, at this time, the cylinder left end detection switch 17 is turned on, and in response to the ON signal, a command signal is output from the controller 19 to the electromagnetic clutch 12 so that both flanges 12a and 12b of the electromagnetic clutch 12 are released. To be separated. Therefore, the steering wheel 5 is released from the direct mechanical link 6 of the steering control valve 4 and idles.

Then, as shown in FIG. 5, when the handle 5 further rotates to the left 5L by the deviation amount ε and reaches the handle left end position H _L , the handle left end detection switch 15 is turned ON. Then, based on the ON signal, the controller 19 connects the flanges 12a and 12b of the electromagnetic clutch 12 again. As a result, the handle 5 is again restrained by the direct mechanical link 6 and the leftward rotation limit is reached, and the deviation amount ε is offset, and the rotation position of the handle 5 and the stroke of the cylinder rod 13 match. Come to do. Thus, the positional deviation between the steering wheel 5 and the steered wheels is corrected, and the drivability and safety are improved.

On the other hand, when the steering wheel 5 is steered to the right 5R from the state shown in FIG. 3, the steering wheel 5 reaches the steering wheel right end position H _R as shown in FIG. Turns on,
At this time, since the cylinder rod 13 has not yet reached the right stroke end C _R, the cylinder right end detection switch 18 has not become to ON. In such a switching state, the electromagnetic clutch 12 is not disengaged by the controller 19.

When the handle 5 is further rotated to the right 5R, as shown in FIG. 7, when the handle 5 exceeds the handle right end position H _R and reaches the right outer side by the deviation amount ε, by the cylinder rod 13 reaches the right stroke end C _R, the handle 5 is in rotation limit to the right. Then, at this time, the cylinder right end detection switch 18 is turned on. Then handle 5
When trying to steer to the left 5L by turning in the opposite direction, both flanges 12a, 12b of the electromagnetic clutch 12 are separated by the controller 19 and the handle 5 idles. Then, as shown in FIG. 8, when the handle 5 has exceeded the handle right end position H _R, the two flanges 12a of the electromagnetic clutch 12, 12b is connected again by the handle right end detecting switch 16 is 0FF To do. Thus, as in the case of FIG. 5, the deviation amount ε is canceled and the correction operation is completed.

Contrary to FIGS. 2 to 8, when the cylinder rod 13 is deviated from the handle 5 toward the right stroke end C _R , the position is changed by a process symmetrical to the above case. The deviation correction is executed.

When the steering wheel 5 is steered to the left or right rotation limit in this way, the electromagnetic clutch 12 is disengaged by the controller 19 immediately before or immediately after the steering wheel 5 reaches the rotation limit, whereby the steering wheel 5 is rotated. 5 and the relative displacement between the cylinder rod 13 are offset. Whether such correction operation is performed immediately before the rotation limit of the handle 5,
Alternatively, whether it is performed immediately after is determined depending on whether the cylinder rod 13 is ahead of or behind the rotation position of the handle 5 until the handle 5 reaches the rotation limit. The correction is performed immediately before the rotation limit, and if it is delayed, the correction is performed immediately after the rotation limit. Here, in the case of the latter delay, the cylinder rod 1
Since 3 is ahead of handle 5,
In other words, when the cylinder rod 13 is ahead of the steering wheel 5 based on the steering direction of the steering wheel 5 at that time, the correction operation is executed near the rotation limit.

Although not shown, the handle-side flange 12a of the electromagnetic clutch 12 is provided with a detecting means for detecting the rotating direction of the handle-side flange 12a. When the steering wheel 5 is steered in the direction opposite to the direction for correcting the positional deviation, the controller 19 immediately connects the electromagnetic clutch 12 by the output of the detecting means. Further, by increasing the number of detection points of the detection means for detecting the rotational position of the handle 5 and the stroke of the cylinder rod 13 and providing a plurality of points at the neutral positions H _N , C _{N and the} like, more precise correction becomes possible. . Furthermore, if the handle 5 is constructed so that an appropriate reaction force is applied to the handle 5 when the handle 5 spins, the electromagnetic clutch 1
It is possible to reduce the uncomfortable feeling of the steering wheel operation that accompanies the contact / separation operation of 2.

Thus, the present invention can be variously modified without departing from the spirit of the present invention, and it goes without saying that the present invention extends to the modified ones.

[0023]

As described above, according to the present invention, when the steering wheel rotation position and the actuator stroke are deviated from each other, and when the actuator stroke is deviated in the steering direction of the steering wheel. , The clutch is disengaged to disconnect the steering wheel and the steering control valve. This offsets the deviation amount between the steering wheel and the actuator, so that the positional deviation between the steering wheel and the steered wheels is corrected. Thus, it is possible to eliminate the deviation of the driving feeling caused by the positional deviation between the steering wheel and the steered wheels, and the drivability and safety are improved.

[Brief description of drawings]

FIG. 1 is a hydraulic and control circuit diagram of an all-hydraulic power steering device according to an embodiment of the present invention.

FIG. 2 is an explanatory view showing a relative positional relationship between a rotation position of a handle and a stroke of a cylinder rod, and a black triangle symbol in the drawing indicates a handle rotation position and a cylinder stroke at the time of explanation of this figure.

FIG. 3 is an explanatory diagram showing a state where the steering wheel is steered to the right by the deviation amount ε from FIG. 2, and a white triangle symbol in the drawing indicates a steering wheel rotation position and a cylinder stroke before steering.

FIG. 4 is an explanatory diagram showing a state in which the steering wheel is steered to the left until the cylinder reaches the left stroke end from FIG. 3;
ON and 0FF in the figure indicate the switching state of each switch after steering the steering wheel.

5 is an explanatory diagram showing a state in which the steering wheel is steered to the left by a deviation amount ε from FIG. 4 to correct the positional deviation.

FIG. 6 is an explanatory view showing a state where the steering wheel is steered rightward from FIG. 3 until the steering wheel reaches the right end position of the steering wheel.

FIG. 7 is an explanatory diagram showing a state in which the steering wheel is steered to the right by the deviation amount ε from FIG. 6 to bring the cylinder to the right stroke end.

FIG. 8 is an explanatory view showing a state in which the steering wheel is turned in the opposite direction from FIG. 7 to correct the positional deviation.

[Explanation of symbols]

1 All-hydraulic power steering device 2 Hydraulic pump 4 Steering control valve 5 Handle 6 Direct mechanical link 11 Power cylinder 12 Electromagnetic clutch 12a Electromagnetic clutch handle side flange 12b Electromagnetic clutch steering control valve side flange 13 Cylinder rod 15 Handle left end detection Switch 16 Handle right end detection switch 17 Cylinder left end detection switch 18 Cylinder right end detection switch 19 Controller H _L Handle left end position H _R Handle right end position C _L Cylinder left stroke end C _R Cylinder right stroke end

Claims (1)

[Claims] 1. A steering control valve which is interlocked with a steering wheel adjusts hydraulic oil supplied from a hydraulic pump to an actuator and displaces a stroke of the actuator so that a steering wheel is moved in accordance with a steering amount of the steering wheel. In an all-hydraulic power steering device that steers, the steering wheel and steering control valve are formed by a clutch so that they can be brought into and out of contact with each other, and the detection means detects the rotational position and steering direction of the steering wheel and the stroke of the actuator. When the steering wheel rotation position and the actuator stroke are deviated from each other and the actuator stroke is deviated in the steering direction of the steering wheel, the clutch is disengaged. An all-hydraulic power steering device characterized in that