JP2918982B2 - Steering gear - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a steering device, and more particularly to a steering device capable of steering front and rear wheels even if the rear wheels cannot be steered. About what you do.

(Prior Art) A conventional example will be described with reference to FIG. FIG. 4 is a diagram showing a configuration of a conventional steering device.

First, there are front wheels 1 and 1 and rear wheels 3 and 3. Knuckle arms 5 and 5 are respectively connected to the front wheels 1 and 1, and both knuckle arms 5 and 5 are connected via a link 7.

A link 9 is connected to one of the knuckle arms, and a piston arm 11 is connected to the link 9. The piston arm 11 is connected to an integral power steering (hereinafter referred to as IPS) 13 as a front-wheel steering mechanism.

That is, the gear 15 is attached to the piston arm 11. On the other hand, the IPS 13 has a cylinder 17 and this cylinder 1
And a piston 19 slidably housed in 7. The piston 19 is provided with a rack gear 21. The gear 15 meshes with the rack gear 21.

A switching valve 23 on the front wheel side is attached to the IPS 13, and the switching valve 23 has switching positions 23a, 23b, and 23c. The switching valve 23 includes a steering wheel.
25 are connected.

A hydraulic pump 27 on the front wheel side is arranged, and this hydraulic pump 27 is driven by an engine 29 of the vehicle, sucks and pressurizes hydraulic oil in a tank 31, and switches the switching valve 23 and the hydraulic piping 3.
Supply and distribute to the IPS 13 via 3 and 34.

Thereby, the piston 19 is slid to either one,
The piston arm 11 is rotated via the rack gear 21 and the gear 15. By the rotation of the piston arm 11, the front wheels 1, 1 are steered in an appropriate direction via the links 9, 7, and the knuckle arms 5, 5.

In addition, another switching valve 35 as a second switching means is interposed between the hydraulic pipes 33 and 34. This switching valve
35 has switching positions 35a and 35b, and when the solenoid 37 is not excited, the compression coil spring 39
The position has been switched to the switching position 35a. When the solenoid 37 is excited, the position is switched to the switching position 35b.

The switching valve 35 is for selecting a front wheel steering mode in which only the front wheels 1 and 1 are steered and a front and rear steering mode in which the front wheels 1 and 1 and the rear wheels 3 and 3 are steered. The function thereof will be described later. I do.

Now, for the rear wheels 3, 3
41, 41 are connected, these two knuckle arms 41,
41 is connected via a link 43.

Between one knuckle arm 41 and the frame 45 of the vehicle,
Booster cylinder (hereinafter BPS) as a rear-wheel steering mechanism
47) is attached. The BPS 47 includes a cylinder 49 and a piston 51 slidably accommodated in the cylinder 49.

Further, the BPS 47 is provided with a switching valve 53 on the rear wheel side, and the switching valve 53 has switching positions 53a, 53b, 53c.

On the other hand, a hydraulic pump 55 on the rear wheel side is provided, and this hydraulic pump 55 is
The hydraulic oil inside is sucked and pressurized, and is supplied to and discharged from the BPS 47 via the hydraulic pipes 61 and 62. Thereby, piston 5
1 and the cylinder 49 slide relatively, and the knuckle arm 4
1. The rear wheels 3, 3 are steered in an appropriate direction via the link 43.

The switching valve 53 is switched by a centering cylinder (S-CYL) 63 as first switching means. The S-CYL 63 has a cylinder 65 and a cylinder 6
It comprises a piston 67 slidably housed in 5, a compression coil spring 69 and the like.

A piston rod 71 connected to the piston 67 is connected to the switching valve 53 via a connecting member 73. Further, hydraulic pipes 33 and 34 extending from the front wheels 1 and 1 are connected to the S-CYL 63.

 The operation will be described based on the above configuration.

First, the case of the front wheel steering mode in which only the front wheels 1 and 1 are steered will be described. In this case, the rear wheel side is locked by a lock device (not shown), and the switching valve 35 is switched to the switching position 35a.

Next, for example, the steering wheel 25 is rotated clockwise. Thereby, the switching valve 23 switches to the switching position 23a.
At that time, the hydraulic oil sucked and pressurized by the hydraulic pump 27 is supplied to one chamber 17a of the IPS 13 via the switching valve 23, the hydraulic pipe 33, the switching valve 35, and the hydraulic pipe 34.

Thereby, the piston 19 is moved upward in the drawing, and the hydraulic oil in the other chamber b is returned to the tank 31. When the piston 19 moves in this manner, the piston arm 11 rotates clockwise in the figure via the rack gear 21 and the gear 15.
Then, the front wheels 1, 1 are steered to the right via the links 9, 7, and the knuckle arms 5, 5.

Next, a case where the steering wheel 25 is rotated to the left will be described. In this case, the switching valve 23 is switched to the switching position 23c.
And the pressure oil of the pump 27 is pressurized into the other chamber 17b of the IPS 13, and the flow is reverse to the above. Therefore, the front wheels 1, 1 are steered to the left.

When a predetermined amount of steering is completed, the switching valve 23 returns to the switching position 23b, and the piston 19 of the IPS 13 also stops.

Also, during such front wheel steering, the rear wheel side is in the following state. First, since the switching valve 35 has been switched to the switching position 35a, in the S-CYL 63, the piston 6
The pressure on both sides of 7 is in the same pressure state.

Therefore, the switching valve 53 is switched to the switching position 53 which is the neutral position.
The hydraulic oil held by b and sucked and pressurized by the hydraulic pump 55 returns to the tank 59 via the switching valve 53. Therefore, the rear wheels 3, 3 are not steered.

Next, the case of the front and rear wheel steering mode in which the front wheels 1 and 1 are steered and the rear wheels 3 and 3 are simultaneously steered will be described.

In this case, the lock by the lock device (not shown) provided on the rear wheel side is released, and the switching valve 35 is released.
Is switched to the switching position 35b.

Then, for example, it is assumed that the steering handle 25 is rotated right. The switching valve 23 switches to the switching position 23a. The hydraulic oil sucked and pressurized by the hydraulic pump 27 is supplied to the switching valve 2
3. It flows into one chamber 65a of the S-CYL 63 via the hydraulic pipe 33.

As a result, the piston 67 moves upward in the drawing, and the hydraulic oil in the other chamber 65b flows through the hydraulic pipe 34 to the I
The power is supplied to one chamber 17a of the PS 13, and the front wheels 1, 1 are steered according to the above-described principle.

On the other hand, the rise of the piston 67 causes the piston rod
The switching valve 53 is switched to the switching position 53 via the 71 and the connecting member 73.
Switch to c. The hydraulic oil sucked and pressurized by the hydraulic pump 55 due to the switching and the switching of the valve 53 is BP
It is supplied to one chamber 49a of S47.

As a result, the piston 51 and the cylinder 49 relatively move, and the rear wheels 3, 3 are steered to the left via the knuckle arms 41, 41 and the link 43. Also, the other chamber of the piston 51
The 49b hydraulic oil is returned to the tank.

Next, when the steering wheel 25 is rotated, the front wheels 1 and 1 are steered to the left and the rear wheels 3 and 3 are steered to the right by the reverse operation.

When a predetermined amount of steering is performed, the switching valve 53 returns to the neutral switching position 53b, and the steering is completed.

(Problem to be Solved by the Invention) According to the above-described conventional configuration, there are the following problems.

First, in the front and rear wheel steering mode, the steering of the rear wheels 3, 3 may be disabled. For example, when the rear wheels 3, 3 fall into a gutter or a depression and steering becomes impossible, or when the lock device functions and locks.

In that case, the BPS 47 is locked, and the S-CYL 63 mechanically connected to the BPS 47 is also locked. Therefore, there is a problem that the supply of the hydraulic oil to the front wheels becomes impossible, and eventually, the steering of the front wheels 1 and 1 also becomes impossible.

Also, in the front wheel steering mode, when the switching valve 35 is switched to the switching position 35b due to an erroneous signal, the front wheels 1,
1 steering becomes impossible. That is, when the front wheels are steered, the rear wheels are locked.
This is because no hydraulic oil is supplied via -CYL63.

The present invention has been made based on such a point, and the object thereof is that, when steering on the rear wheel side becomes impossible during front and rear wheel steering mode, and when the switching valve malfunctions during front wheel steering mode. Also in this case, a steering device capable of steering the front wheels is provided.

(Means for Solving the Problems) In order to achieve the above object, the present invention is directed to a front-wheel-side steering mechanism that operates according to pressure left in chambers on both sides of a piston to steer a front wheel in an appropriate direction, and rotation of a steering wheel. A front-wheel switching valve that switches by operation to switch the flow direction from the front-wheel hydraulic pump to the front-wheel steering mechanism, and a rear-wheel side that operates by the pressure difference between the chambers on both sides of the piston to steer the rear wheel in an appropriate direction. A steering mechanism, a rear-wheel switching valve for switching the flow direction from the rear-wheel hydraulic pump to the rear-wheel steering mechanism, and a first switching for switching the rear-wheel switching valve operated by a pressure difference between chambers on both sides of the piston. Means for communicating one of the chambers of the front-wheel steering mechanism with the front-wheel switching valve in the front-wheel steering mode, and cutting off the communication in the front-rear wheel steering mode; ~ side A hydraulic pipe for guiding the hydraulic oil on the switching valve side to a predetermined chamber of the first switching means, and a hydraulic oil for the front wheel side steering mechanism from the second switching means to a chamber separate from the predetermined chamber of the first switching means. It is assumed that the steering is provided with a hydraulic pipe leading to the vehicle.

The present invention is characterized in that a differential pressure switching valve is provided for communicating between the pair of hydraulic pipes when a predetermined differential pressure is generated between the pair of hydraulic pipes.

(Operation) First, the second switching means causes the front wheel-side steering mechanism to perform the first
A description will be given of the case where the supply of the hydraulic oil to the switching means is permitted and the front and rear wheel steering mode is set.

At this time, it is assumed that the rear wheel side cannot be steered for some reason, and thereby the first switching means is locked.

Due to the lock of the first switching means, a differential pressure is generated between the hydraulic passages between the front wheel steering mechanism and the first switching means. Due to this differential pressure, the differential pressure switching valve is operated, and the hydraulic oil directed from the front wheel side steering mechanism to the first switching means is bypassed and supplied to the front wheel side steering means. Thereby, steering on the front wheel side becomes possible.

Next, a case where the supply of hydraulic oil from the front wheel steering mechanism to the first switching means is restricted by the second switching means and the front wheel steering mode is set will be described. In this case, the rear wheel is locked.

At this time, it is assumed that the supply of the hydraulic oil from the front wheel side steering mechanism to the first switching means is permitted due to a malfunction of the second switching means.

Also in this case, the differential pressure switching valve is switched by the differential pressure generated due to the locking of the first switching means, and the hydraulic oil is supplied to the front wheel side steering mechanism, so that the front wheel side can be steered.

(Embodiment) A first embodiment of the present invention will be described below with reference to FIGS.

The same parts as those in the related art are denoted by the same reference numerals, and description thereof is omitted.

In the case of the present embodiment, a differential pressure switching valve 101 is interposed between the front wheel side and the rear wheel side. The differential pressure switching valve 101 is connected to hydraulic pipings 33 and 34 via hydraulic passages 103 and 104.

The differential pressure switching valve 101 has switching positions 101a, 101b, 101
c. The switching position 101b shuts off the flow path, and the switching positions 101a and 101c open the flow path. The switching positions 101a and 101c have apertures 113 and 113, respectively.

Further, the pressure on the hydraulic passages 103, 104 side is changed to the pressure introduction passages 109, 111.
And these pressure introduction paths 109, 1
The diaphragm 11 is provided with apertures 105 and 105, respectively.

Note that reference numerals 115 and 117 in the figure denote compression coil springs.
The differential pressure switching valve 101 is held at a neutral switching position 101b.

The differential pressure switching valve 101 has, for example, a configuration as shown in FIG. First, there is a valve body 121, in which a valve spool 123 is housed so as to be slidable in the left-right direction in the figure.

Caps 12 are located at both ends of the valve spool 123.
5, 127 are screwed. Between the valve spool 123 and the cap 125, the compression coil spring 1 already described
15 and a spring guide 129 are mounted. Further, between the valve spool 123 and the cap 127, the above-described compression coil spring 117 and spring guide 131 are mounted.

Other parts corresponding to the parts shown in FIG. 1 are denoted by the same reference numerals.

 The operation will be described based on the above configuration.

First, the case where the steering wheel 25 is rotated clockwise in the front and rear wheel steering mode will be described. In this case, the lock on the rear wheel side is released, the switching valve 35 is switched to the switching position 35b, and the differential pressure switching valve 101 is switched to the neutral switching position 101b.

If the rear wheels can be steered, the front wheels 1, 1 and the rear wheels 3, 3 are steered in appropriate directions by the same operation as described in the description of the conventional example.

At that time, it is assumed that the steering on the rear wheel side is disabled for some reason. In this case, the S-CYL 63 is locked, and the sliding of the piston 67 is restricted.
The pressure inside rises.

As a result, a differential pressure is generated between the hydraulic pipes 33 and 34, and acts on the differential pressure switching valve 101. as a result,
The differential pressure switching valve 101 switches to the switching position 101c. Therefore, the hydraulic pipes 33 and 34 communicate with each other via the switching position 101c, and the hydraulic oil on the hydraulic pipe 33 side is supplied to the front wheels via the hydraulic pipe 34. Thereby, steering on the front wheel side becomes possible.

The same applies to the case where the steering wheel 25 is rotated counterclockwise. In this case, the pressure on the hydraulic pipe 34 side increases, and the differential pressure switching valve 101 switches to the switching position 101a. .

By the way, in such a series of operations, the apertures 105, 113
Works as follows. First, regarding the restrictor 105, the function of the dynamic pressure from the hydraulic pipes 33 and 34 is relaxed to prevent unnecessary operation and unnecessary vibration of the differential pressure switching valve 101.

The throttle 113 is, for example, a differential pressure switching valve 101.
Operates to switch to the switching positions 101a and 101c.
In this case, the differential pressure decreases sharply, but if it is applied as it is, the differential pressure switching valve 10
1 will vibrate unnecessarily.

Therefore, an appropriate differential pressure is continuously generated by the throttles 113, 113 to prevent the vibration.

Next, a case where the switching valve 35 is switched to the switching position 35b due to an erroneous signal in the front wheel steering mode will be described.

In this case, the rear wheel is locked and S-
Since the CYL 63 is locked, the differential pressure switching valve 101 is switched to the switching position 101a or 101 by the same operation as described above.
Switch to c.

As a result, the supply of hydraulic oil to the front wheels is guaranteed, and the front wheels 1, 1 can be steered.

According to the present embodiment, the following effects can be obtained.

First, in the front and rear wheel steering mode, even if steering on the rear wheel side is disabled for some reason, steering on the front wheel side is reliably guaranteed. This is because the operation of the differential pressure switching valve 101 ensures the supply of hydraulic oil to the front wheels.

Also, in the front wheel steering mode, when the switching valve 35 is switched to the switching position 35b due to an erroneous signal,
Steering on the front wheel side is guaranteed. This is also a differential pressure switching valve
This is because the operation of 101 ensures the supply of hydraulic oil to the front wheels.

Further, by switching with the differential pressure switching valve 101, it is possible to prevent an overload from acting on the S-CYL 63 and maintain its soundness.

The differential pressure switching valve 101 has throttles 105, 105 and a throttle 11
Since the three and 113 are provided, unnecessary operation and vibration of the differential pressure switching valve 101 can be prevented.

Next, a second embodiment will be described with reference to FIG. In this embodiment, the throttles 113, 113 in the first embodiment are arranged in the hydraulic passages 103, 104. Other configurations are the same as those in the first embodiment, and description thereof will be omitted.

In the case of this embodiment, the same effects as in the case of the first embodiment can be obtained.

(Effect of the Invention) As described in detail above, according to the steering device of the present invention,
Due to the operation of the differential pressure switching valve, the hydraulic oil flowing from the front wheel side steering mechanism to the first switching means is bypassed and supplied to the front wheel side steering mechanism, so that the rear wheels cannot be steered in the front and rear wheel steering mode. , Or when the second switching means malfunctions in the front wheel steering mode, the steering of the front wheels can be ensured.

[Brief description of the drawings]

1 and 2 are views showing a first embodiment of the present invention. FIG. 1 is a configuration diagram of a steering device, FIG. 2 is a cross-sectional view of a differential pressure switching valve, and FIG. 3 is a second embodiment. Diagram of the steering device according to FIG.
FIG. 1 is a configuration diagram of a conventional steering device. 1 front wheel 3 rear wheel 13 front wheel steering mechanism
IPS, 23 ... Switching valve as front wheel switching valve, 2
5 ... steering wheel, 35 ... switching valve as second switching means, 47 ... BPS as rear wheel side steering mechanism, 53 ... switching valve as rear wheel side switching valve, 63 ... first switching means S-CYL, 101 ... Differential pressure switching valve.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Shinichi Hagihira 2548 Tsuchida, Kani-shi, Gifu Kayaba Industrial Co., Ltd. Gifu North Plant (56) References 141078 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) B62D 7/14 B62D 5/07

Claims (1)

(57) [Claims] 1. A front wheel steering mechanism which operates by a pressure difference between chambers on both sides of a piston to steer a front wheel in an appropriate direction and a front wheel side hydraulic pump which is switched by a rotation operation of a steering wheel. Front-wheel switching valve that switches the flow direction to the rear, a rear-wheel steering mechanism that operates by the pressure difference between the chambers on both sides of the piston to steer the rear wheel in an appropriate direction, and rear-wheel steering from the rear-wheel hydraulic pump. A rear-wheel switching valve that switches the flow direction to the mechanism, a first switching unit that operates by a pressure difference between chambers on both sides of the piston to switch the rear-wheel switching valve, or a front-wheel steering mechanism in the front-wheel steering mode. Second switching means for communicating one of the chambers with the front-wheel-side switching valve and cutting off the communication in the front-rear wheel steering mode;
A hydraulic pipe for guiding hydraulic oil on the front wheel side switching valve side from the switching means to a predetermined chamber of the first switching means, and hydraulic oil for a front wheel steering mechanism from the second switching means is supplied to the predetermined chamber of the first switching means. When a predetermined differential pressure is generated between the pair of hydraulic pipes,
A steering device comprising a differential pressure switching valve communicating between the hydraulic pipes.