JPS6291373A - Front and rear wheel steering device for vehicle - Google Patents

Abstract

PURPOSE:To enable the neutral position of rear wheels to be maintained during high speed running, by a method wherein working oil is fed to a rear wheel cylinder, capable of steering rear wheels, in linkage with rotation of a handle rotary shaft, during high speed running, the rear wheels can be steered through the working of a centering mechanism, and during low speed running, the rear wheels can be steered following steering of front wheels. CONSTITUTION:When a handle H is operated so that front wheels Tf are turned in either a right or a left direction, rear wheels Tr can be also automatically steered following said steering. During linear running, the front wheels Tf are not steered and the rear wheels Tr are not steered, but when reliable stop of steering is executed, the feed of working oil to a rear wheel cylinder C is stopped. Especially during high speed running, with a rear wheel centering mechanism 2 actuated, a neutral position is maintained through utilization of a spring force. Thus, when turn or oblique running during low speed running of a working vehicle is executed, the rear wheels can be steered following steering of the front wheel Tf. When a vehicle is switched to high speed running, steering of the rear wheels is stopped, and the neutral position of the rear wheels can be easily maintained.

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, which is configured so that the rear wheels are also steered following front wheel steering.

[Conventional technology]

For work vehicles such as trucks, front and rear wheel steering is used to follow the front wheel steering and steer the rear wheels in order to quickly and efficiently turn when driving at low speeds and slant to change course. A method has been proposed.

For example, according to a proposal in Japanese Patent Application Laid-Open No. 59-143769, the device has a controller and is equipped with various sensors such as a vehicle speed sensor and a steering wheel operation angle sensor, and the detection signals from the various sensors are The actuation signals that are input to the controller and processed by the controller are output to various valves, and the valve control enables steering of the rear wheels when the vehicle is running at low speed.

Therefore, by equipping the controller with a full range of sensors and processing power to adjust the operation of various valves,
This allows the desired front and rear wheel steering of the car/vehicle.

[Problem that the invention seeks to solve]

However, the conventional proposal has the disadvantage of increasing the cost of the device itself.

In other words, in the above-mentioned conventional proposals, although the rear wheel steering that follows the front wheel steering when the vehicle is running at low speed must always be reproduced to the desired extent, the characteristics of the valve may change. As a result, there is a risk that the steering situation of the rear wheels may change, and in order to prevent this risk from occurring at all, further maintenance of the controller is required, which increases the cost of the device. There are certain inconveniences.

SUMMARY OF THE INVENTION In view of the above-mentioned circumstances, it is an object of the present invention to provide a new front and rear wheel steering device for a vehicle that does not increase costs.

[Means for solving problems]

In order to solve the above-mentioned problems, the configuration of the present invention is such that hydraulic oil can be supplied from an oil supply mechanism to the rear wheel cylinder that enables steering of the rear wheels, and the oil supply mechanism is configured to steer the front wheels. It is formed so as to be linked with the rotation of the handle rotation shaft.

〔Example〕

The present invention will be described below based on illustrated embodiments.

FIG. 1 shows a front and rear wheel steering device for a vehicle according to the present invention, which has a power steering mechanism PS on the front wheel Tf side and a rear wheel cylinder Or on the rear wheel Tr side. The oil supply mechanism 1 is formed to be interlocked with the power steering mechanism PS when the power steering mechanism PS is operated.

The power steering mechanism PS includes a pitman arm α that swings when the handle H for steering the front wheels Tf is operated.
is connected to the pitman arm α, and a drag rod rl is connected to the pitman arm α, and the front wheel Tγ is formed to turn in a predetermined manner by movement of the drag rod. It should be noted that the power steering mechanism PS is configured such that when the power steering mechanism PS is operated, hydraulic oil from the tank TO flows from the front wheel pump Pf, and the hydraulic oil is returned to the tank TO.

The oil supply mechanism 1 is formed so as to supply hydraulic oil from the rear wheel pump Pr to the rear wheel cylinder Cγ via the main supply and discharge passages L/Lz and return it to the tank TO during its operation, Its operation is performed by the power steering mechanism P
The rotation operation of the handle H is performed at the same time as the rotation operation of the handle H.

That is, a gear G is formed on the handle rotation axis whose base end engages with the power steering mechanism Ps, and a gear 10 that enables the operation of the oil supply mechanism I is meshed with the gear G. The fuel supply mechanism 1 is always operated when the handle H is operated for steering the front wheels. Note that the oil supply mechanism 1 is not separately specified with respect to its configuration, as long as it can supply a desired amount of hydraulic oil to the rear wheel cylinder Or in conjunction with the operation of the hashidor H, but it is not specified separately in this embodiment. In this case, it is assumed that the vehicle is comprised of all-hydraulic power steering devices called so-called H, P, and S.

The rear wheel cylinder Cr is formed as a so-called double rod type, in which both ends of a rod body protruding from the cylinder body are connected to a rod r2 connected to the rear wheel Tγ.

Although not shown, hydraulic oil can be supplied from the oil supply mechanism 1 into two oil chambers partitioned on the left and right inside the cylinder body.

It is formed so that the hydraulic oil can be discharged from the two oil chambers to the supply mechanism 1. In this embodiment, the rear wheel cylinder Cr is of a so-called double-rod type, but it may be of a single-rod type instead.

A solenoid valve V is disposed in the middle of the main supply/discharge passages L/, L, 2 to allow communication and isolation of both the passages L/, LJ. The solenoid valve Vy
/ is both L/ when the solenoid is not energized.
, L2 is formed so as to bypass and communicate with the valve ■S, and the oil supply mechanism 1 is connected to the rear wheel cylinder Or side.
The hydraulic oil is not supplied from the oil supply mechanism 1, and when the solenoid is energized, the hydraulic oil from the oil supply mechanism 1 is supplied to the rear wheel cylinder Or. In addition, the above solenoid valve V, r/
In this embodiment, the excitation of the solenoid is 1 when the traveling speed of the vehicle is a constant value on the speedometer M (for example, 351 an/m).
A) is performed automatically, or it is configured so that it can be performed manually using switch Sm until the vehicle speed reaches the above-mentioned constant value, and when the solenoid is energized, That is the indicator lamp I
It is designed so that it is displayed when it lights up.

Therefore, according to the present embodiment, when the steering wheel H is operated to turn the front wheel Tr to either the left or right side, the front wheel Tr follows the operation of the front wheel Tf.

The rear wheels Tr can always be automatically steered by so-called hydraulic operation. When the vehicle travels in a straight line, the front wheels Tf[theta] are not steered - therefore, the rear wheels T[gamma] are not steered, but when the steering of the rear wheels Tr is stopped more reliably.

It is sufficient to stop the supply of hydraulic oil to the rear wheel cylinder Cr. In particular, when the vehicle is running at high speed, the following rear wheel centering mechanism 2 according to the present invention is used. As shown in FIG. 2, it is provided with a spring 21 in a housing 20 and a bushing rod 22 energized by the spring 21. 22 has a piston-like base 23 that slides within the housing 20, and has an air chamber 24 defined by the piston-like base 23.The tip of the bushing rod 22 is When the pressure inside the air chamber 24 is released, it is formed so as to come into contact with the side surface of the knuckle arm N extending parallel to the neutral direction of the rear wheel Tr. If so, the knuckle arm N has a guide rod n.
protrudes in a direction perpendicular to the extending direction of the knuckle arm N, that is, in a direction parallel to the one rear wheel axle R, and the guide roller is inserted through the solid axis of the pusher rod 22. This allows the bushing rod 22 to slide along the guide roller.

Therefore, when pressurized air is supplied from the external air tank Ta (see figure +1) into the air chamber 24 through the port 25, the piston-like base 23 moves inside the housing 20 against the repulsive force of the spring 21. At this time, the tip of the bushing rod 22 is unseated from the side surface of the knuckle arm N, and the knuckle arm N is able to swing upward in the circumferential direction with the center being below the tooth 2 in the figure. That is, the rear wheel Tr can be steered.

And when the above atmospheric pressure is lifted.

The bushing rod 22 is slid to the right in FIG. 2 by the repulsive force of the spring 210, and the tip of the bushing rod 22 is seated on the side of the knuckle arm N, causing the knuckle arm N to swing.

That is, the steering of the rear wheels Tr is stopped.

At this time, a gap δ is formed between the piston-like base 23 of the bushing rod 22 and the housing 20, that is, between the sliding direction of the bushing rod 22, and the tip of the bushing rod 22 contacts the side surface of the knuckle arm N. The piston-like base 23 and the housing 20 are brought into contact with each other.

For knuckle arm N. Care has been taken to ensure that the so-called steering lock does not become incomplete.

Note that one end of the housing 20 is pivoted to the other part 2 (for example, the vehicle body), and the other end of the housing 20 is centered around the pivot part.

In other words, the bushing rod 22 can freely swing on its side.

The air chamber 24 of the rear wheel centering mechanism 2 is as follows.

It communicates with an external air tank T (Z). That is, as shown in Figure 1, the vehicle has an exhaust brake (
Since the air tank T (not shown) is equipped with an air tank T (Z), the air tank Tα is used as a pressure air supply source, and the pressure air from the air tank Tα is supplied to the blowout prevention valve V and the solenoid valve v, ? The solenoid valve 'h2 is configured to supply air into the air chamber 24 through a The solenoid is formed so as to enable communication between the supply and exhaust passage La and the air tank Tc, that is, to supply pressurized air into the air chamber 24, by excitation.Then, the excitation of the solenoid is released. When this happens, the air chamber 24 is configured to allow the pressurized air in the air chamber 24 to flow back through the supply/discharge path La and to be released to the outside through the throttle t.

Note that the blowout prevention valve υ is used in cases where there is a failure in the air chamber 24 section, the supply/discharge path La section, or the solenoid valves V, r, and 2 sections, causing pressure to be blown out unnecessarily from the air tank Tα. It is designed to prevent this from happening.

Therefore, by equipping the rear wheel centering mechanism 2,
When stopping the steering of the rear wheels Tγ.

Not only is the supply of hydraulic oil to the rear wheel cylinder Or stopped, but the neutral position of the rear wheel Tr is forcibly maintained reliably. By operating the solenoid valve ■52, the rear wheels Tr can be freely steered, so that the solenoid valve ■52 can be freely steered. Even if the rear wheel centering mechanism 2 cannot be expected to operate normally due to a failure of the rear wheel Tr, the rear wheel Tr is always maintained in a neutral state.

In addition, the excitation to the solenoid valves V and 9z is as follows.

Of course, this is done at the same time and in the same system as the above-mentioned turenoid valve ①8.

〔Effect of the invention〕

As described above, according to the present invention, it is of course possible to always make rear wheel steering possible by following the front wheel steering when a work vehicle such as a truck is turning or going diagonally at low speed. , when the vehicle shifts to high-speed driving, the steering of the rear wheels is stopped.

This has the advantage that it is possible to easily maintain the neutral position of the rear wheels.

Further, according to the present invention, in maintaining the rear wheel neutral position,
Since spring force is used, there is no need to separately equip a fluid pressure supply device such as hydraulic pressure to keep the rear wheels neutral.

The hydraulic pressure used in the front and rear wheel steering devices can be limited to the hydraulic pressure for operating the rear wheel cylinders.

This has the advantage that the entire device can be made smaller and lighter.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a front and rear wheel steering device for a vehicle according to the present invention, and FIG. 2 is a sectional view showing a rear wheel neutralization device in the present invention. l... Refueling mechanism, 2... Rear wheel centering mechanism,
Or...Rear cylinder, H...Handle. L/, L! ...Main supply and exhaust path, PS...Power steering mechanism, Tf...Front wheel, Tr...Rear wheel. Procedural amendment (voluntary) ゛November 1985 lN-1 1. Indication of the case 1985 Patent Application No. 214044 2. Title of the invention Address Name (092) Kayabae Gyo Co., Ltd. 4th Director Address Yaesu Building, 2-10-8 Yaesu, Chuo-ku, Tokyo (271) 7854-5 (1) Column for detailed explanation of the invention in the specification (1) On page 2, line 14 of the specification, it says, ``The steering shall be steered.'' It has been corrected to read, ``The steering shall be steered.'' (2) On page 3, line 6 of the specification, it says "for adjustment of operation", and on line 7 of the same, it says "by equipment of" [by equipment of large objects] And, in line 20 of the same statement, it is corrected to read ``improving the capacity of'' instead of ``improving the.'' (3) On page 5, line 14 of the specification, the phrase ``supplied to,'' should be corrected to ``measured and supplied to.'' (4) On page 6, line 5 of the specification, it says, ``In addition, the above-mentioned oil supply mechanism l... It goes without saying that a belt transmission type using a belt pulley may also be used.

Claims (4)

[Claims] (1) In a front and rear wheel steering system for a vehicle configured to enable steering of the rear wheels in accordance with the steering of the front wheels, the rear wheel cylinders that enable steering of the rear wheels are provided with a fuel supply mechanism. A front and rear wheel steering device for a vehicle, in which a hydraulic oil can be supplied, and the oil supply mechanism is configured to be linked with rotation of a steering wheel rotation shaft for steering the front wheels. (2) A front and rear wheel steering device for a vehicle as set forth in claim 1, wherein the front wheel steering device is configured so that the front wheels can be steered by a power steering mechanism. (3) A rear wheel centering mechanism is installed on the rear wheel side of the vehicle so that when the vehicle speed exceeds a set speed, the spring force generated when the fluid pressure is released makes it impossible to steer the rear wheels. A front and rear wheel steering device for a vehicle according to claim 1. (4) The front and rear wheels of a vehicle according to claim 1 are configured such that when the vehicle speed exceeds a set vehicle speed, the supply of hydraulic oil from the oil supply mechanism to the rear wheel cylinders is disabled. Control device.