JPS6271759A - Four-wheel steering gear for vehicle - Google Patents

Abstract

PURPOSE:To make the desired steering of rear wheels performable all the time according to a front wheel controlled variable at low cost, by setting up a metering valve, setting up a metering cylinder to set a stroke value of a rear- wheel cylinder, in a front-wheel steering wheel in an interlocking manner. CONSTITUTION:At a metering valve 1a, when a spool 11 being connected to a Pitman arm (a) is slidden, for example, to the right, a hydraulic fluid out of a rear-wheel pump Pr is regulated by lands 11a-11d, flowing out to an oil passage l1, and it flows into the inside of a rod side chamber 14a of a metering cylinder 1b. Therefore, a piston 13 is relatively slidden to a cylinder body 10, oil inside a piston side chamber 13a flows out to the valve 1a via an oil passage l2. And, it flows into the inside of an expansion side chamber A of a rear-wheel cylinder Cr via a feed-discharge passage L1, while the oil flows into the inside of the valve 1a via a feed-discharge passage L2, and put back to a tank To. With this constitution, operation of the Pitman arm is transmitted to rear wheels without using a sensor and a controller so that manufacturing cost is reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement in a front and rear wheel steering device for a vehicle in which the rear wheels are also steered following front wheel steering during vehicle operation.

[Conventional technology]

When a work vehicle such as a truck turns at low speed or travels diagonally to change course, it is preferable to do so quickly and efficiently.

Therefore, various proposals have been made for front and rear wheel steering devices in which the rear wheels are also steered when the front wheels of a vehicle are steered.

For example, according to a proposal in Japanese Patent Application Laid-Open No. 59-143769, the device has a controller and various sensors such as a vehicle speed sensor, a steering wheel operation angle sensor, etc. A signal is manually input to the controller, and a signal is output from the controller to enable the operation of a hydraulic power source and various valves, etc., and as a result, the rear wheels are enabled to be steered when the front wheels are steered. ing.

Therefore, desired front and rear wheel steering can be achieved by providing various valves, sensors, etc., and improving the processing ability of the controller.

[Problem that the invention seeks to solve]

However, the conventional proposal has disadvantages in that the cost of the device increases and its versatility is reduced.

That is, when driving a vehicle, the driver generally learns how much the rear wheels are steered and what trajectory the vehicle will travel by operating the steering wheel to control the front wheels. Therefore, unless the rear wheels are steered as desired by the driver depending on the magnitude of the steering wheel operation, driving the vehicle becomes extremely dangerous.

However, if we try to achieve the above basic requirements with the devices related to the conventional proposals, it will be necessary to increase the number of various sensors and the processing capacity of the controller, and at the same time, it will be necessary to increase the number of various sensors operated by the commands of the controller. There are inconveniences such as the need for more valves, which increases the cost of the entire device, and which necessitates the omission of installation in low-cost vehicles, which reduces its versatility.

Therefore, the present invention has developed a new front and rear wheel steering device for a vehicle that allows the rear wheels to always perform the desired steering according to the amount of front wheel steering without requiring the installation of various sensors or controller equipment. The purpose is to provide

[Means for solving problems]

In order to solve the above-mentioned problems, the configuration of the present invention is such that the front wheel side of the vehicle is provided with a metering valve that is linked to the steering wheel operation for steering the front wheels, and the rear wheel side of the vehicle is provided with the metering valve that is linked to the steering wheel operation for controlling the front wheels. A rear wheel cylinder is arranged to enable steering of the rear wheels by supplying hydraulic oil from a metering valve, and a metering cylinder is arranged in the metering valve to set the stroke amount of the rear wheel cylinder. It is characterized by the presence of

〔Example〕

The present invention will be explained below based on the illustrated embodiments.

As shown in Figure 1, the front and rear wheel steering system for a vehicle according to an embodiment of the present invention has a power steering mechanism PS on the front wheel Tf side that receives hydraulic oil from a front wheel pump Pf, and a power steering mechanism PS that receives hydraulic oil from a front wheel pump Pf. A rear wheel cylinder Or is provided on the Tr side to receive hydraulic oil from a rear wheel pump Pr.

A pitman arm α is connected to the power steering mechanism PS, which is swung when a handle H for steering the front wheels is operated, and a drag rod r/ is connected to the pitman arm α, and the drag rod γ is connected to the pitman arm α. The front wheels Tf disposed at both ends of the front wheel axle F by the movement of
is formed so that it undergoes a predetermined turn.

On the other hand, an oil supply mechanism 1 that enables the supply of hydraulic oil to the rear wheel cylinder Or and controls the flow rate thereof is connected to the pitman arm α.

That is, as shown in Fig. 2, the oil supply mechanism 1 consists of a metering valve 1α and a metering cylinder 1b, and in this embodiment, the metering valve 1α part and the metering cylinder 1h part is formed within a single housing member 10, one end on the metering valve 1α side is connected to the pitman arm α, and one end on the metering cylinder 1h side is connected to the other part b (
For example, it is fixed to the vehicle body. The metering valve 1α portion has a spool 11 whose one end is connected to the pitman arm α, and the spool 11 is connected to the housing member 1 by a plate spring 12 disposed in contact with both ends of the spool 11. It is designed to be balanced within.

The interior of the housing member 10 in the metering valve 1α portion is communicated with the rear wheel pump pr (see Fig. 1) and the tank TO (see Fig. 1) of each part, as well as with the rear wheel cylinder Cγ, Moreover, it is in communication with the metering cylinder 1h. And spool 1
1 is in the neutral state, even if there is a flow of hydraulic oil from the rear wheel pump Pτ, the flow will flow to the tank TO side, and will not flow to the metering cylinder 1h, but also to the rear wheel cylinder Or. Although not supplied, when the spool 11 is slid by the swinging of the pitman arm α, the hydraulic oil from the rear wheel pump Pr flows into the housing member 10 and into the oil path I! , or 1.2, to the metering cylinder 1h side.

The metering cylinder 1h has a piston 13 that slides on the housing member 10 as a cylinder body, and a piston rod 1 connected to the piston 13.
By fixing the end of 4 to the other part 6 as the end of the metering cylinder 1h, relative movement of the piston 13 within the cylinder body is enabled. The inside of the rod side chamber 14α in the cylinder body is communicated with the metering valve 1α via an oil passage 1, and the inside of the piston side chamber 13α is also communicated via an oil passage.

Therefore, in the metering valve 1α, when the spool 11 is slid, for example, to the right in FIG. Land portions 11C, l at both ends
id and flows out into [oil passage j), and the hydraulic oil in the oil passage l flows into the rod side chamber 14α of the metering cylinder 1b.

As the hydraulic oil flows into the rod side chamber 14α, the piston 13 slides relative to the cylinder body, that is, the housing member 10, and the oil in the piston side chamber 13α flows into the oil passage 10. It flows out into the metering valve 1α through the metering valve 1α. Further, the hydraulic oil flowing into the metering valve 1α side from the metering cylinder 1h is passed through one main supply/discharge path L/ (see Fig. 1) to the extension of the so-called single-rod type rear wheel cylinder Cr. The hydraulic oil in the pressure side chamber B flows into the side chamber A and expands the rear wheel cylinder Cr, and the hydraulic oil in the pressure side chamber B flows into the metering valve 1α through another main supply/discharge path Lλ(
(See Figure 1) and is returned to the tank To.

Therefore, in this embodiment, if the spool 11 moves to the right when the front wheel Tf is turned to the left, and the rear wheel cylinder Cr is extended and the rear wheel Tr is also turned to the left, the spool 11 moves to the left. When the vehicle moves forward, the rear wheels Tr are turned to the right, that is, the rear wheels Tr can be steered in the same direction as the steering direction of the front wheels Tf. And, as shown in Figure 1,
If a switching valve (2) is installed in the main supply/discharge path L/LJ, it becomes possible to steer the rear wheels Tr in the opposite direction to the steering direction of the front wheels Tf.

In addition, when the hydraulic oil capacity of the piston side chamber 13α in the metering cylinder 1h and the expansion side chamber A of the rear wheel cylinder Cr communicating therewith is made equal, the rear wheel When the cylinder Cr strokes and the hydraulic oil capacity is in a proportional relationship, the stroke amount of the rear wheel cylinder Or becomes a stroke proportional to the stroke amount of the metering cylinder 1b. That is, it is possible to always steer the rear wheels Tr as desired in accordance with the desired operation of the power steering mechanism PS when steering the front wheels Tf.

Note that when the vehicle travels in a straight line, the front wheels Tf are not steered, and therefore the rear wheels Tr are not steered. It is sufficient to stop the supply of hydraulic oil to Cr.

Fig. 3 shows another embodiment of the present invention, and in this embodiment, a control valve part 2 of the power steering mechanism PS that enables steering of the front wheel Tf is provided with a control valve part 2 of the rear wheel Tr. A metering valve 1α (see Fig. 4) that enables the supply of hydraulic oil to the rear wheel cylinder Cr that enables steering is provided, and the metering cylinder 1b is configured in accordance with the above-mentioned power steering mechanism PS. Pitman arm α and other parts b (e.g. car body) that swing during operation
It is assumed that it is located between.

That is, as shown in Figure 4, the control valve section 2 includes a planet valve 2α that is driven by operating the handle H (see Figure 3), and a planet valve 2α that is driven by the operation of the handle H (see Figure 3).
a steering valve 2b operated by the drive of the steering valve 2b;
The metering valve 1α is operated by driving the planet valve 2α.

The planet valve 2α has a rotating shaft 20 of the handle H inserted through its center, a plurality of planetary gears 21 meshing with the rotating shaft 20, and a ring gear 22 meshing with the planetary gears 21. That's what happens.

Therefore, when the rotating shaft 20 is rotated by operating the handle H, the ring gear 22 rotates coaxially, and the pin 23 implanted in the ring gear 22 rotates.
．． 24 switches and operates each of the valves 26°1α.

The steering valve 26 has a spool 26 that slides inside the valve housing 25 as appropriate, and the pin 24 is connected to a central land portion 26α of the spool 26. The land portions 26A and 26C formed at both ends of the spool 26 and the central land portion 26α regulate the flow of hydraulic oil from the front wheel pump Pf (see Fig. 3), and the power steering This allows hydraulic oil to be supplied to the mechanism PS, and also allows return hydraulic oil from the power steering mechanism PS to flow into the tank Tl) (see Figure 3).

Further, the metering valve 1α includes a spool 16 that slides within the valve housing 15, and is connected to the pin 24 at a central land portion 1612 of the spool 16. The flow of hydraulic oil from the rear wheel pump Pr (see Figure 3) is regulated by land portions 16, 6, 16C at the intermediate portion of the spool 16 and land portions 16d, 16e at both ends of the spool 16, Oil line l to the metering cylinder 1h! l or lλ, and is also supplied to the rear wheel cylinder Cr (see Fig. 3) via the main supply/discharge path L/or Lλ (see Fig. 3), and from the rear cylinder Or. While letting the return oil flow in, the tank T
o (see figure 3).

Therefore, in this embodiment, when steering the front wheel Tf, the metering valve 1α as the refueling mechanism 1 (see Fig. 1) is operated together with the steering valve 2h, and the metering cylinder 1b is used to set the metering valve 1α. This capacity of hydraulic oil is supplied to the so-called surface rod type rear wheel cylinder Cr, and the rear wheel Tr can be steered by the rear wheel cylinder CT.

In addition, in this embodiment, the metering cylinder 1h, which uses the hydraulic oil from the metering valve 1α as a set volume and flows out to the rear wheel cylinder C7 side, is connected to other parts 6 such as the vehicle body, as shown in FIG. One end of a rod body 18 connected to a piston body (not shown) arranged to partition two oil chambers (not shown) in the connected cylinder body 17 and extending to the left and right of the cylinder body 17. is connected to the pitman arm a, and the piston body in the cylinder body 17 is slid by the swinging of the pitman arm α, and a predetermined amount of hydraulic oil flows out from one oil chamber to the rear wheel cylinder Or side. It is formed.

In addition, in this embodiment, the rear wheel cylinder Cr is
A connecting rod r3 is a so-called side rod type and is configured similarly to the metering cylinder 16, and as shown in FIG. 3, both ends of an O-rad body r2 are connected to the rear wheel Tr
The above-mentioned metering cylinder 1
It is formed so that the rod bodies r and 2 are slid in proportion to the stroke profile and M etc. due to the hydraulic oil capacity from h to steer the rear wheel Tr.

In the embodiment of the present invention shown in Fig. 1 and Fig. 3, a solenoid valve ■s/ is provided in the main supply/discharge path L/, Lλ that communicates the metering valve 1a and the rear wheel cylinder Cγ. is installed, and the solenoid valve V
When demagnetizing the s7 solenoid, use one main supply/discharge path/
. For example, it is configured so that it can be performed automatically when the speed reaches 35 km/A, or it can be performed manually using switch Sm. In addition,
When the solenoid is energized, an indicator lamp is lit.

In addition, in the embodiment of the present invention shown in FIGS. 1 and 3, when the rear wheel Tr does not require steering, for example, when the vehicle runs at the certain speed or higher, the rear wheel Tr
A rear wheel centering mechanism 3 is provided to maintain the rear wheel in a so-called neutral position. The rear wheel centering mechanism 3 includes a bushing rod 30 that comes into contact with the knuckle arm of the rear wheel Tr, and a spring 31 that biases the bushing rod 30 toward the knuckle arm. Pressure of solenoid valve V
, rλ, the bushing rod 30 is moved backward to release the restraint of the knuckle armle, and the bushing rod 30 is formed so as to restrain the swinging of the knuckle armle when the pressure is released.

Note that the pressure from the air tank Tα is controlled by the blowout prevention valve υ disposed intermediately up to the solenoid valve Vs2, so that even if there is a failure on the rear wheel center ring mechanism 3 side, the solenoid valves V, r- It is formed in such a way that it is prevented in advance from ejecting to the side without restriction.

Furthermore, the power steering mechanism PS in the embodiment of the present invention shown in Figs. Furthermore, in the embodiment shown in FIG. 4, instead of using the so-called planet type valve 2a that switches between the steering valve 2h and the metering valve 1α, the rotating shaft 2 of the handle H is used.
At 00 revolutions, the direct meeting valves 2b and 1α may be switched and operated.

〔Effect of the invention〕

As described above, according to the present invention, the metering valve for steering the rear wheels is operated simultaneously when the front wheels are steered, so that turning or diagonal running at low speed in a work vehicle such as a truck can be quickly performed. Moreover, it has the advantage of being able to be carried out efficiently.

Further, according to the present invention, since the metering cylinder is disposed between the metering valve and the rear wheel cylinder, it is possible to always steer the rear wheels in a manner equal to or proportional to the amount of operation of the front wheels. This allows the driver to easily learn the driving characteristics of the vehicle.

Furthermore, according to the present invention, the installation of various sensors such as a steering wheel operation angle sensor and a vehicle speed sensor can be omitted, and the equipment of a controller is also unnecessary, which contributes to reducing the cost of the entire device and improving its versatility. That will happen.

Furthermore, according to the present invention, by installing a metering valve in the power steering mechanism part,
Further, by integrally forming the metering valve and the metering cylinder and installing the metering valve in the pitman arm portion, there is an advantage that the entire device can be simplified.

4. Brief explanation of the drawings 2. -・,,9 Fang 1
The figure is a circuit diagram showing a front and rear wheel steering device according to an embodiment of the present invention, Figure 2 is a sectional view showing the oil supply mechanism according to the present invention together with a rear wheel cylinder, and Figure 3 is a circuit diagram showing another embodiment of the oil supply mechanism according to the present invention. FIG. 4 is a schematic diagram showing a control valve portion of the power steering mechanism according to the present invention.

■・・・Supply mechanism, 1α・Φ・metering valve, 1
b...metering cylinder, 2. ...Control valve section, 2α...Steering valve, 3...
Rear wheel centering mechanism, Or... rear wheel cylinder, F.
...Front wheel axle, H...handle, L/, L, 2...
Main supply/discharge path, Pf...front wheel pump, Pr...rear wheel pump, PS...power steering mechanism, R.
...Rear wheel axle, Tf...front wheel, Tr...rear wheel.

Claims (6)

[Claims] (1) In a front and rear wheel steering system for a vehicle configured to allow steering of the front wheels as well as steering of the rear wheels, a metering valve is provided on the front wheel side of the vehicle in conjunction with the steering wheel operation for steering the front wheels. In addition, a rear wheel cylinder is provided on the rear wheel side of the vehicle to enable steering of the rear wheels by supplying hydraulic fluid from the metering valve, and a metering valve is provided on the rear wheel side of the vehicle. A front and rear wheel steering device for a vehicle, characterized in that a metering cylinder for setting a stroke amount of a rear wheel cylinder is disposed in the valve. (2) The front and rear of the vehicle according to claim 1 is formed such that steering of the rear wheels becomes impossible by stopping the supply of hydraulic oil to the rear wheel cylinders when the vehicle speed exceeds a certain speed. Wheel steering device. (3) Claim 1, wherein the front wheels are configured to be controlled by a power steering mechanism, and a metering valve is disposed in a control valve section of the power steering mechanism. Front and rear wheel steering system for the vehicle described. (4) The front and rear wheel steering device for a vehicle according to claim 1, wherein the metering cylinder is formed to steer the rear wheels by the same amount or in proportion to the amount of steering of the front wheels. (5) The metering valve is formed integrally with the metering cylinder, and one end on the metering valve side is connected to the pitman arm of the front wheel, and one end on the metering cylinder side is connected to the other part. A front and rear wheel steering device for a vehicle according to claim 1, which is fixed. (6) The metering cylinder is formed separately from the metering valve, and the rod end of the metering cylinder is connected to the pitman arm of the front wheel,
The front and rear wheel steering device for a vehicle according to claim 1, wherein the cylinder body of the metering cylinder is fixed to another part.