JPH045169A - Steering device - Google Patents

Abstract

PURPOSE:To perform the steering of front wheels positively even at the time of rear wheels being out of steering by feeding operating oil, flowing from front wheel side steering mechanism to a switching means, into the front wheel side steering mechanism by way of a detour by the action of differential pressure type relief valves. CONSTITUTION:In this four wheel steering gear, a switching valve 35 for selecting either a front wheel steering mode or a front-rear wheel steering mode is interposed between hydraulic pipelines 33, 34 for feeding/discharging operating oil to/from an power cylinder 13 by the action of a switching valve 23 connected to a steering wheel 25. A switching valve 53 is provided at a booster cylinder 47, and this valve 53 is switched by a centering cylinder 63. In this case, a pair of differential pressure type relief valves 101, 103 are interposed between the front and rear wheel sides. Pressure between hydraulic passages 105, 107 and between 111, 109 is to act respectively upon the valves 101, 103.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a steering device, and in particular, in a steering device capable of front and rear wheel steering, it is possible to steer the front wheels even when the rear wheels become unsteerable. Concerning what you do.

(Prior Art) A conventional example will be explained with reference to FIG. FIG. 3 is a diagram showing the configuration of a conventional steering device.6 First, there are a front wheel 1.1 and a rear wheel 3.3. A knuckle arm 5.5 is connected to each of the front wheels 1.1, and these two knuckle arms 5.5 are connected via a link 7.

A link 9 is connected to one knuckle arm 5, and a piston arm 11 is connected to this link 9. This piston arm 11 is equipped with an integral power steering system (hereinafter referred to as IPS) as a front wheel steering mechanism.
) 13.

That is, a gear 15 is attached to the piston arm 11. On the other hand, the IP813 is composed of a cylinder 17 and a piston 19 slidably housed within the cylinder 17. A rack gear 21 is provided on the piston 19. The gear 15 meshes with the rack gear 21.

A switching valve 23 is attached to the IP913, and this switching valve 23 has switching values W23a, 23b,
It is equipped with 23c. Further, a steering handle 25 is connected to the switching valve 23.

A hydraulic pump 27 is arranged, and this hydraulic pump 27
is driven by the engine 29 of the vehicle, sucks and pressurizes the hydraulic oil in the tank 31, and connects the switching valve 23 and the hydraulic piping 3.
3.34, it is supplied to and discharged from the above IP513.

thereby causing the piston 19 to slide to either side,
Piston arm via rack gear 21 and gear 15]
Rotate 1. This rotation of the piston arm 11 steers the front wheel 1.1 in an appropriate direction via the link 9.7 and the knuckle arm 5.5.

Note that another switching valve 35 as a second switching means is inserted between the hydraulic pipes 33 and 34. This switching valve 35 has switching values M35a, 35b, and is switched to a switching position 35a by a compression coil spring 39 when the solenoid 37 is de-energized. Also, when the solenoid 37 is energized, the switching position 35
Switch to b.

This switching valve 35 is for selecting between a front wheel steering mode in which only the front wheels 1.1 are steered and a front and rear wheel steering mode in which the front wheels 1.1 and rear wheels 3.3 are steered. This will be explained later.

Now, the rear wheels are 3.3, but each knuckle arm is 4.
1 and 41 are connected, and these two knuckle arms 4
1.41 are connected via link 43.

Between one knuckle arm 41 and the frame 45 of the vehicle, a booster cylinder (hereinafter referred to as B
(referred to as PS) 47 is installed. This BPS47
is composed of a cylinder 49 and a piston 51 slidably housed within the cylinder 49.

Further, the BPS 47 is provided with a switching valve 53, and this switching valve 53 has switching values W53a, 53b, 5
It is equipped with 3c.

On the other hand, a hydraulic pump 55 is installed, and this hydraulic pump 55 is driven by an engine 57, sucks and pressurizes the hydraulic oil in the tank 59, and supplies and discharges it to the BPS 47 via hydraulic piping 61 and 62. do. Thereby, the piston 51 and the cylinder 49 are caused to slide relative to each other, and the rear wheel 3.3 is steered in an appropriate direction via the knuckle arm 41 and the link 43.

A centering cylinder (hereinafter referred to as 5-CYL) 6 serving as a first switching means switches the switching valve 53.
It is 3. This 5-CYL 63 has a cylinder 65,
Piston 6 slidably housed within this cylinder 65
7, a compression coil spring 69, etc.

The piston rod 71 connected to the piston 67 is
It is connected to the switching valve 53 via a connecting member 73. Moreover, hydraulic pipes 33.34 extending from the front wheel 1.1 side are connected to this 5-CYL 63.

The operation will be explained based on the above configuration.

First, the case of the front wheel steering mode in which only the front wheels 1.1 are steered will be explained. In this case, the rear wheel side is locked with a locking device W (not shown), and the switching valve 35 is switched to the switching position 35a.

Next, for example, the steering handle 25 is rotated clockwise. Thereby, the switching valve 23 is switched to the switching position 23a. At that time, the hydraulic oil sucked and pressurized by the hydraulic pump 27 is transferred to one chamber 1 of the IP813 via the switching valve 23, the hydraulic piping 33, the switching valve 35, and the hydraulic piping 34.
7a, the piston 19 is moved upward in the figure, and the hydraulic oil in the other chamber 17b 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. And link 9.7,
Via the knuckle arm 5.5, the front wheel 1.1 is steered to the right.

Next, a case will be described in which the steering wheel 25 is rotated to the left. In this case, the switching valve 23 is switched to the switching position device 23c, and the pump 2 is connected to the chamber 17b of the IPS 13.
No. 7 pressure oil is supplied, and the flow is opposite to that described above. The front wheel 1.1 will therefore be steered to the left.

Note that when the predetermined amount of steering is completed, the switching valve 23 returns to the switching position 23b, and the piston 19 of the IP 513 also stops operating.

Further, during such front wheel steering, the rear wheels are in the following state. First, the switching valve 35 is at the switching position W35a.
Since it has been switched to , in 5-CYL 63,
The pressure on both sides of the piston 67 is the same.

Therefore, the switching valve 53 is in the switching position 5 which is the neutral position.
The hydraulic oil held in the tank 3b 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, a case of a front and rear wheel steering mode in which the front wheels 1.1 are steered and the rear wheels 33 are also steered at the same time will be described.

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

For example, assume that the steering wheel 25 is rotated clockwise. The switching valve 23 is switched to the switching position 23a. The hydraulic oil sucked and pressurized by the hydraulic pump 27 flows into one chamber 65a of the 5-CYL 63 via the switching valve 23 and the hydraulic piping 33.

As a result, the piston 67 moves upward in the figure, and the hydraulic oil in the other chamber 65b is supplied to one chamber 17a of the IP813 via the hydraulic pipe 34, and the front wheels 1.1 are steered according to the above-described principle. will be done.

On the other hand, as the piston 67 rises, the switching valve 53 is switched to the switching position 53c via the piston rod 71 and the connecting member 73. By switching the switching valve 53, the hydraulic oil sucked and pressurized by the hydraulic pump 55 is supplied to one chamber 49a of the BPS 47.

As a result, the piston 51 and the cylinder 49 move relative to each other, and the rear wheel 3.3 is steered to the left via the knuckle arm 41 = 41 and the link 43. is returned to the tank 59.

Next, when the steering wheel 25 is rotated to the left, the front wheels 1.1 are steered to the left and the rear wheels 3.3 are steered to the right by an operation opposite to the above.

Note that when a predetermined amount of steering is performed, the switching valve 53 returns to the neutral switching position IE53b, and the steering is completed.

(Problem to be solved by the invention) The conventional configuration described above has the following problems.

First, in the front and rear wheel steering mode, steering of the rear wheels 3.3 may become impossible. For example, this may occur if the rear wheel 3.3 falls into a side bank or a depression and becomes unsteerable, or if the locking device malfunctions and becomes locked.

In that case, BPS47 becomes locked and BPS4
5-CYL 63 mechanically connected to 7 is also in a locked state. Therefore, there is a problem in that it becomes impossible to supply hydraulic oil to the front wheels, and as a result, it becomes impossible to steer the front wheels 1.1.

Also, in the front wheel steering mode, if the switching valve 35 is switched to the switching position 35b due to an erroneous signal, the front wheel 1
．． 1 becomes unable to steer.

That is, when the front wheels are steered, the rear wheels are locked, and hydraulic oil is not supplied through the 5-CYL 63.

The present invention has been made based on the above points, and its purpose is to solve the following problems: when the rear wheels cannot be steered during the front and rear wheel steering mode, and when the switching valve malfunctions during the front wheel steering mode. Another object of the present invention is to provide a steering device that enables steering of the front wheels.

(Means for Solving the Problems) In order to achieve the above object, a steering device according to the present invention is operated by hydraulic oil supplied through a front wheel side switching valve that is switched appropriately by rotational operation of a steering wheel, and controls the front wheels as appropriate. a front wheel steering mechanism that steers the rear wheels in an appropriate direction; a rear wheel steering mechanism that steers the rear wheels in an appropriate direction using hydraulic fluid supplied through a rear wheel switching valve; and a rear wheel steering mechanism located close to the rear wheel steering mechanism. a first switching means operated by hydraulic oil supplied via the front wheel steering mechanism to switch the rear wheel switching valve, and the front wheel steering mechanism and the rear wheel steering mechanism. By regulating the supply of hydraulic oil from the front wheel steering mechanism to the first switching means, the front wheel steering mode is set, and by allowing the supply of hydraulic oil from the front wheel steering mechanism to the first switching means, the front and rear wheels are controlled. A second switching means for setting the steering mode is inserted between the first switching means and the second switching means, and the second switching means is inserted when the front wheel side steering mechanism is allowed to supply hydraulic oil to the first switching means. A pair of differential pressure switches that are activated by the differential pressure generated when the first switching means is locked, bypassing hydraulic oil directed to the first switching means and supplying it to the front wheel steering mechanism to enable front wheel steering. The device is characterized by being equipped with a pressure relief valve.

(Function) First, a case will be described in which the second switching means allows the supply of hydraulic oil from the front wheel side steering mechanism to the first switching means and the front and rear wheel steering mode is set.

At this time, it is assumed that the rear wheels become unable to be steered for some reason, and as a result, the first switching means becomes locked.

Due to the locking of the first switching means, a pressure difference is generated between the hydraulic flow path between the front wheel side steering mechanism and the first switching means. This differential pressure causes one of the differential pressure relief valves to operate, causing hydraulic fluid directed from the front wheel steering mechanism to the first switching means to be detoured and supplied to the front wheel steering mechanism. This makes it possible to steer the front wheels.

Next, the second switching means switches the front wheel steering mechanism to the first steering mechanism.
A case where the supply of hydraulic oil to the switching means is regulated and the vehicle is in front wheel steering mode will be described. In this case, the rear wheels are locked.

At this time, it is assumed that the second switching means malfunctions and allows the supply of hydraulic oil from the front wheel steering mechanism to the first switching means.

In this case as well, the differential pressure generated by the first switching means being locked switches one of the differential pressure relief valves, and hydraulic oil is supplied to the front wheel steering mechanism.
It is possible to steer the front wheels.The other differential pressure relief valve functions based on the same logic when the steering wheel is rotated in the opposite direction to the above, and enables steering of the front wheels. It is.

(Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

Incidentally, the same parts as in the prior art are denoted by the same reference numerals, and the explanation thereof will be omitted.

In the case of this embodiment, a pair of differential pressure relief valves 101 and 103 are inserted between the front wheel side and the rear wheel side. The differential pressure type relief valve 101 has hydraulic piping 33.34.
and are connected via hydraulic flow paths 105 and 107. Further, the differential pressure type relief valve 103 is connected to the hydraulic piping 33.
34 via hydraulic flow paths 109 and 111.

The differential pressure relief valve 101 includes a pressure introduction path 11
3.115, the pressure on the hydraulic flow path 105.107 side acts. When there is no differential pressure, the compression coil spring 121 is in a state as shown in the figure, and the hydraulic pipes 33 and 34 are in a state of being cut off.

On the other hand, when the differential pressure becomes large, the state is switched to the left side in the figure against the spring force of the compression coil spring 121, and the hydraulic pipes 33 and 34 are brought into communication.

Similarly, the differential pressure relief valve 103 is connected to a hydraulic flow path 111.109 via a pressure introduction path 119.117.
Side pressure is applied. When there is no differential pressure, the compression coil spring 123 is in a state as shown in the figure, and the hydraulic pipes 34 and 33 are cut off.

On the other hand, when the differential pressure becomes large, the state is switched to the right side in the figure against the spring force of the compression coil spring 123, and the hydraulic pipes 34 and 33 are brought into communication. Specifically, the pressure relief valves 101 and 103 have a configuration as shown in FIG. 2, for example. What is shown here is the differential pressure type relief valve 101.
．． 103 are integrated.

First, there is a valve body 131, and this valve body 1
31, side plates 133, 135 are attached. The side plate 133 has the hydraulic passage 105 (or 109) formed therein, and the side plate 135 has the hydraulic passage 107 (or 111) formed therein.The valve body 131 has a valve seat. 1
37 is attached to this valve seat 137,
The valve body 139 is pressed from below in the figure by the compression coil spring 121 described above. That is, under normal conditions, the valve body 139 is pressed against the valve seat 137 by the compression coil spring 121 and is in a closed state.

On the other hand, when the differential pressure becomes large, the valve body 13 resists the spring force of the compression coil spring 121.
9 is pressed down, thereby opening the valve.

A valve seat 141 and a valve body 143 are arranged in the valve body 131 in an arrangement opposite to that described above, and the valve body 143 is pressed against the valve seat 141 by the compression coil spring 123 described above.

Also in this case, the valve is selectively opened by the same action as described above.

The operation will be explained based on the above configuration.

First, a case will be described in which the steering handle 25 is rotated clockwise in the front and rear wheel steering mode. In this case, the lock on the rear wheel side is released, and the switching valve 35 has the switching value ff35.
b and differential pressure relief valve 1.
01.103 is in the closed state.

If the rear wheels can be steered, the front wheels 11 and rear wheels 3.3
is steered in an appropriate direction.

At this time, it is assumed that steering of the rear wheels becomes impossible for some reason. In this case, the 5-CYL 63 is in a locked state and the sliding of the piston 67 is restricted, so the pressure inside the hydraulic pipe 33 increases, which causes a differential pressure between the hydraulic pipes 33 and 34. is generated, and this differential pressure acts on the differential pressure type relief valve 101. As a result, the differential pressure relief valve 101 is opened, the hydraulic pipes 33 and 34 are communicated, and the hydraulic oil on the hydraulic pipe 33 side is supplied to one chamber 17a of the IP 313 via the hydraulic pipe 34. This makes it possible to steer the front wheels.

This also applies when the steering handle 25 is rotated to the left. In that case, the pressure on the hydraulic piping 34 side increases, so the differential pressure relief valve 103 is opened.

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

In this case, the lock is on the rear wheel side and the 5-C
Since YL 63 is locked, the differential pressure relief valve 101 or 103 is opened by the same action as described above.

This ensures the supply of hydraulic oil to the front wheels,
Steering of the front wheels 1.1 becomes possible.

According to this embodiment, the following effects can be achieved.

First, in the front and rear wheel steering mode, even if rear wheel steering becomes impossible for some reason, front wheel steering is reliably guaranteed. This is the differential pressure relief valve 101 or 10
This is because the operation in step 3 ensures the supply of hydraulic oil to the front wheels.

Furthermore, even if the switching valve 35 is switched to the switching position 35b due to an erroneous signal in the front wheel steering mode, the steering of the front wheels is guaranteed. This is also because the operation of the differential pressure relief valve 101 or 103 ensures the supply of hydraulic oil to the front wheels.

In addition, the action of the differential pressure relief valves 101 and 103 prevents overload from acting on the 5-CYL 63, making it possible to maintain the integrity of the 5-CYL 63 and improve the design margin. Can be expanded.

Note that the present invention is not limited to the above embodiment.

For example, in the above-mentioned embodiment, the pair of differential pressure relief valves are integrated, but they may be separate units, or various other types may be considered.

(Effects of the Invention) As detailed above, according to the steering device according to the present invention,
Due to the action of the differential pressure relief valve, the hydraulic fluid from the front wheel steering mechanism to the first switching means is bypassed and supplied to the front wheel steering mechanism, so that the rear wheel steering is not possible when in the front and rear wheel steering mode. Even if the second switching means malfunctions in the front wheel steering mode, the steering of the front wheels can be reliably guaranteed.

[Brief explanation of the drawing]

1 and 2 are diagrams showing a first embodiment of the present invention, in which FIG. 1 is a configuration diagram of a steering device, FIG. 2 is a sectional view of a differential pressure type switching valve, and FIG. 3 is a conventional steering device. FIG. l...Front wheel, 3...Rear wheel, 13...IPS as a front wheel steering mechanism, 23...Switching valve as a front wheel side switching valve 1.25...Steering handle, 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... 5 as first switching means
-CYL, 101, 103... Differential pressure relief valve. Patent attorney Nobuyuki Shima (Representative for the applicant) July 5, 1991 2. Name of the invention Steering device 3. Relationship with the person making the amendment Patent applicant address 2-4 Hamamatsucho, Minato-ku, Tokyo World Trade Center Building No. 1 Name (092) Kayabae Gyo Co., Ltd. Representative Kei Chano 4 Agent 〒150 21! (340915040
Address: 3-28-15 Shibuya, Shibuya-ku, Tokyo Claims column of the specification, Detailed description of the invention (1) The Claims column of the specification will be amended as follows. 2. Claims: A front wheel steering mechanism that steers the front wheels in an appropriate direction by being operated by hydraulic oil supplied through a front wheel switching valve that is switched as appropriate by rotation of a steering handle; a rear wheel steering mechanism that steers the rear wheels in an appropriate direction using hydraulic oil supplied through a valve; and a hydraulic oil supplied through the front wheel steering mechanism that is located close to the rear wheel steering mechanism. A first switching means that operates to switch the rear wheel side switching valve, and a first switching means that is inserted between the front wheel steering mechanism and the first switching means and supplies hydraulic oil from the front wheel steering mechanism to the first switching means. a second switching means for setting the front wheel steering mode by regulating the front wheel steering mechanism and setting the front wheel steering mode by permitting the supply of hydraulic oil from the front wheel steering mechanism to the first switching means; Switching is performed by the differential pressure generated when the first switching means is locked when the front wheel side steering mechanism is inserted between the front wheel steering mechanism and the first switching means and the hydraulic oil is allowed to be supplied to the first switching means. A steering device comprising: a pair of differential pressure relief valves that bypass hydraulic fluid directed toward a first switching means and supply it to a front wheel steering mechanism to enable front wheel steering. (2) In the 5th line of page 8 of the specification, the phrase [via the switching valve 53] has been replaced with "switching valve 53, hydraulic piping 61.62.
"via," corrected. (3) In the same book, page 11, lines 17 to 18, the phrase "rear wheel steering mechanism" is corrected to read "first switching means." (4) In the third line of page 12 of the same book, the phrase "first switching means and second switching means" is amended to read "front wheel side steering mechanism and first switching means." (5) In the same book, page 19, line 17, "design margin" is corrected to "design margin." (6) In the same book, page 20, lines 15 to 16, the phrase "differential pressure type switching valve" is corrected to "differential pressure type relief valve." (7) Figures 1 and 3 of the drawings will be amended as shown in the attached sheet.

Claims (1)

[Claims] A front wheel steering mechanism that operates with hydraulic oil supplied through a front wheel switching valve that is switched appropriately by rotating the steering wheel to steer the front wheels in an appropriate direction, and a rear wheel switching valve that operates with hydraulic fluid. a rear wheel steering mechanism that uses hydraulic oil to steer the rear wheels in an appropriate direction; and a rear wheel steering mechanism that is arranged close to the rear wheel steering mechanism and is operated by hydraulic oil supplied via the front wheel steering mechanism to steer the rear wheels. A first switching means for switching the switching valve is inserted between the front wheel steering mechanism and the rear wheel steering mechanism, and controls the supply of hydraulic fluid from the front wheel steering mechanism to the first switching means. a second switching means for setting the steering mode and for setting the front and rear wheel steering mode by allowing the supply of hydraulic oil from the front wheel side steering mechanism to the first switching means; and the first switching means and the second switching means. When the hydraulic oil is allowed to be supplied from the front wheel side steering mechanism to the first switching means, the first switching means is locked, and the first switching means switches due to the differential pressure generated. A steering device comprising: a pair of differential pressure relief valves that bypass and supply hydraulic oil to a front wheel steering mechanism to enable steering of the front wheels.