JPS6274768A - Rear wheel centering device for tront/rear wheel steering vehicle - Google Patents

Abstract

PURPOSE:To make possible to maintain the neutral position of a rear wheel with an economical device by providing a rear wheel centering mechanizm on the rear wheel side of a vehicle for stopping the steering of the rear wheel by spring force at the time when a vehicle speed excceeds the predetermined value. CONSTITUTION:In case of a front/rear wheel steering vehicle, a rear wheel steering device is provided with a rear wheel cylinder <Cr> to which a working oil, whose flow rate is controlled by an oiling mechanizm mounted on a front wheel steering device, is supplied and the rear wheel <Tr> is steered by the power of said cylinder through a tie rod <r2>. In this case, the rear wheel centering mechanizms 1 are mounted at the position adjacent to the right and left rear wheels <Tr> respectively. Each centering mechanism 1 is provided with a pushing rod 12 which is energized by a spring 11 housed into a houging 10. And, at the time when the pressure in a pressure chamber 14 is discharged because a car speed exceeds the predetermined value (for example, 35Km/h), the pushing rod 12 is seated to the side surface of a nuckle arm <N>, thereby it is functioned to stop the steering of the rear wheel <Tr>.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement of a rear wheel neutralization device for a front and rear wheel steered vehicle that is formed so that the rear wheels are also steered following the front wheel steering. .

[Conventional technology]

For work vehicles such as trucks, a front and rear wheel steering system is used in which the rear wheels are also steered to follow the front wheel steering in order to quickly and efficiently turn when driving at low speeds and slant to change course. In addition, there has been a proposal to maintain the rear wheels in a neutral position as in the past when the work vehicle is traveling at high speed.

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 In addition to applying human power to the controller, the actuation signals processed by the controller are output to various valves, and the valve control allows the rear wheels to be steered when the vehicle is running at low speeds, and the rear wheels to be in a neutral position when the vehicle is running at high speeds. It is designed to be maintainable.

Therefore, by equipping each scale with sensors and processing capacity of the controller to adjust the operation of various valves,
This allows desired rear wheel steering and maintenance of the rear wheel neutral device.

[Problem that the invention seeks to solve]

However, the conventional proposal has the disadvantage of causing so-called work loss in the device, and
This has the disadvantage of increasing the cost of the device itself.

That is, in the above-mentioned conventional proposal, the cylinder for steering the rear wheels operates in a manner that resists the above-mentioned steering force when maintaining the rear wheels in a neutral position. Therefore, for supplying hydraulic oil to the above cylinder, for example,
In the power steering mechanism for the front wheels, there is a disadvantage that so-called output loss is caused.

Furthermore, although the rear wheel steering that follows the front wheel steering when the vehicle is running at low speed must always be reproduced as desired, in the conventional proposals, 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.

Therefore, the present invention provides a rear wheel neutralization device for a front and rear wheel steered vehicle that does not cause so-called work loss and does not increase costs when stopping steering of the rear wheels and maintaining the neutral position. The purpose is to provide new information.

[Means for solving problems]

In order to solve the above-mentioned problems, the configuration of the present invention is such 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. The vehicle is characterized in that a rear wheel centering mechanism is provided.

〔Example〕

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

Figure 1.1 shows one front and rear wheel steering device equipped with a rear wheel neutralization device according to the present invention, and the steering device has a power steering structure PS on the front wheel Tf side and a rear wheel neutralization device. A rear wheel cylinder Cγ is provided on the wheel Tr side, and a rear wheel centering mechanism 1 according to the present invention is provided on the rear wheel Tr side.

The power steering mechanism PS includes a pitman arm α that swings when the handle H for steering the front wheels Tf is operated.
are connected to each other, and the front wheels Tγ disposed at both ends of the front wheel axle F are formed to turn in a predetermined manner by the movement of the drag rod r/.

On the other hand, an oil supply mechanism 2 that supplies hydraulic oil to the rear wheel cylinder Cr and controls its flow rate is connected to the pitman arm α.

That is, the oil supply mechanism 2 consists of a spool-type metering valve 2a and a cylinder-type metering cylinder 2b. In this embodiment, the metering valve 2a portion and the metering cylinder 26 portion are a single unit. One end of the metering valve 2α side is formed in one housing member, and one end of the metering valve 2α side is connected to the pitman arm α.
One end on the metering cylinder 26 side is fixed to the other part h (for example, the vehicle body). And, in the above metering valve 2α part, the external rear wheel pump Pr dimension is
】-4W み空 Ｇｕｎｎｄｎｉｎｔ し １ Ｇ Ｇ Ｇ Ｇ Ｇ Ｇ Ｇ Ｉ Ｇ Ｇ Ｇ Ｇ Ｇ Ｇ Ｇ Ｇ Ｉ Ｇ Ｇ Ｇ Ｇ Ｉ Ｇ Ｇ Ｇ Ｇ Ｇ Ｉ Ｇ Ｇ Ｉ Ｇ Ｇ Ｇ Ｇ Ｉ Ｇ sec 1 R 连线 ri P 名谷wheel cylinder Or and the main supply/discharge passages L/, Lλ communicate with each other via the metering cylinder 2b and the oil passage 1.
/, IIλ.

In addition, in the metering cylinder 26 part,
Although not shown, it has two oil chambers separated by a piston, and one oil chamber, for example, the pressure side oil chamber, is connected to the other oil chamber, that is, the expansion side oil chamber, through the oil passage 11t. The oil chamber is formed to communicate with the inside of the metering valve 2a and the rear wheel cylinder Cr via an oil passage 11x. That is, the oil discharged from the metering cylinder 2h flows into the rear wheel cylinder Or with its discharge capacity, or the oil flowing into the metering cylinder 26 flows out from the rear wheel cylinder Cr at the same amount as the amount of oil flowing into the metering cylinder 26. It is designed to be the same as the original.

Therefore, in this embodiment, the metering cylinder 2
By disposing b, the stroke amount of the rear wheel cylinder Cγ is kept constant, and stable rear wheel steering is possible for hunting. In this embodiment, the stroke amount of the metering cylinder 2b and the stroke amount of the rear wheel cylinder Or are set to be equivalent, but instead of this, each of the above stroke amounts has a proportional relationship. Of course, it is also possible to set it as follows.

In this embodiment, the rear wheel cylinder Or is formed into a so-called single rod type, and one end is connected to the other part A (for example, for the vehicle body), and the other end is connected to the rear wheel axle R. It is connected to a tie rod r2 that steers the held rear wheel Tr.

Further, the power steering mechanism PS is configured to be supplied with hydraulic oil from the front wheel pump Pf when the handle H is operated, and the hydraulic oil is returned to the tank To.

Therefore, according to this embodiment, when the handle H is operated so as to turn the front wheel Tr to either the left or right side, the rear wheel +1'lr follows the operation of the front wheel Tf and automatically moves by a so-called hydraulic operation. It becomes possible to steer the vehicle to and,
When the vehicle travels in a straight line, the front wheels Tf are not steered, so the rear wheels Tr are not steered. It is sufficient to stop the supply of hydraulic oil. In particular, when the vehicle travels at high speed, the following rear wheel centering tatami structure 1 according to the present invention is utilized.

The rear wheel centering mechanism 1 has a tooth 1 as shown in the figure:
It is disposed near the left and right rear wheels Tr, and as shown in Fig. 2, it has a spring 11 in a housing 10 and a bushing rod 12 energized by the spring 11. The bushing rod 12 extends over a piston-shaped base 13 that slides within the housing 10, and
It has an air chamber 14 divided into three sections. The tip of the bushing rod 12 is formed so that the inside of the air chamber 14 comes into contact with the side surface of the knuckle arm N that extends parallel to the neutral direction of the Aoto Yabu-seikan Tr when the air pressure is released. has been done. That is, in this embodiment, the knuckle arm N has a guide roller protruding in a direction perpendicular to the extending direction C of the knuckle arm N, that is, in a direction parallel to the rear wheel axle R. A guide roller is inserted through the solid shaft core of the bushing rod 12, so that the bushing rod 12 slides along with the guide rod n+c.

Therefore, when pressurized air is supplied from the external air tank Ta (i=1, see Figure 1) inside the air chamber 14 (through the port 15), the piston-like base 13 resists the repulsive force of the spring 11 and moves toward the housing. 10 and from 7, at that time, the tip of the bushing rod 12 is brought into contact with the knuckle arm N.
The knuckle arm N can swing upward in the circumferential direction centering on the lower part of the fan 2, that is, the rear wheel Tr can be steered.

Then, when the above-mentioned atmospheric pressure is released, the bushing rod 12 is slid to the right in FIG. The swinging of the knuckle arm N and the steering of the rear wheel Tγ are stopped.

At this time, a gap δ is formed between the piston-like base 13 of the bushing rod 12 and the housing 10, that is, between the sliding direction of the bushing rod 12, and the tip of the bushing rod 12 comes into contact with the side surface of the knuckle arm N. Before the piston-like base 13 and the housing 10 are brought into contact with each other, care is taken to ensure that the so-called steer lock to the knuckle arm N does not become incomplete.

Note that one end of the housing 10 is pivotally attached to another part b (for example, a living body), and the other end of the housing 10, that is, the bush rod 12, is centered around the pivoted part b.
The installation side can be freely swung.

The air chamber 14 of the rear wheel centering mechanism 1 is communicated with an external air tank Tα. That is, as shown in Figure 1, the vehicle has, for example, an exhaust brake (not shown).
Since the air tank Tα is equipped with the air tank Tα for supplying pressurized air, the pressurized air from the air tank Tα is supplied to the air chamber 14 through the blowout prevention valve υ and the solenoid valve vj. It is designed to be supplied within the The above solenoid valve 9.2 is operated when the vehicle speed is at the set value (for example, 35kph).
m/h), the solenoid is energized to connect the supply/discharge path L (Z and the air tank Tα), that is,
The air chamber 14 is formed to allow pressurized air to be supplied into the air chamber 14. Furthermore, when the solenoid is de-energized, the air chamber 14 is configured to allow the pressure air in the air chamber 14 to flow back through the supply/discharge path Lα and to be released to the outside through the throttle t. has been done.

Note that the blowout prevention valve υ is designed to prevent pressure from being blown out from the air tank Ta if there is a failure in either the air chamber 1 = 1 portion, the supply/discharge path Lα portion, or the solenoid valve VSλ portion. It is designed to prevent

Therefore, in the rear wheel centering mechanism 1 according to the present invention, the rear wheel 'fr can be kept in the neutral position without causing losses due to so-called work loss in the oil supply mechanism 2 for steering the rear wheel Tar and the power steering mechanism PS. It becomes possible to maintain the position.

In the embodiment of the present invention, as shown in FIG.
When the solenoid valve Vsi is operated, the hydraulic oil from the oil supply mechanism 2 is supplied to the rear wheel cylinder Or, and the rear wheel cylinder Cr is expanded and contracted as desired. When the solenoid valve Vsi is not activated, the hydraulic oil from the oil supply mechanism 2 is not supplied to the rear wheel cylinder Or but returns to the tank TOK. When the rear wheel Tr is stopped by the wheel centering mechanism 1, the steering is stopped more reliably.

In this embodiment, the excitation of the solenoids of the solenoid valves Vst, V, and r2 is performed when the traveling speed of the vehicle is a constant value as measured by the speedometer M (for example, 35 km/h).
The process is performed automatically until , or switch Sm
It is assumed that the system is configured so that it can be operated manually until the vehicle speed reaches the above-mentioned constant speed, and if a failure occurs in the solenoid valves V and P2, normal operation of the rear wheel centering mechanism 1 is expected. When this is not possible, the rear wheel Tr is always maintained in a neutral state.

Further, when each of the solenoids is energized, this is indicated by lighting of a display lamp.

Figure 3 shows another embodiment of the present invention. In this embodiment, the operating angle of the handle H which is rotated when the front wheel Tf is operated is detected, and the rotation of the rear wheel Tr is detected. By comparing the detected value with the rudder state, the rear wheels Tγ are steered to follow the steering of the front wheels Tf, and the vehicle speed is detected and when the vehicle speed exceeds the set value, the rear wheels Tr are steered. The main valve 3, which supplies hydraulic oil to the rear wheel cylinder Gr for sliding, is returned to neutral, and the rear wheel centering mechanism 1 according to the present invention maintains the neutral position of the rear wheel Tγ. This is what I did to get it.

Therefore, in this embodiment 0, 'tt is attached to the rotating shaft portion of the handle H, and a handle operation angle detector CA (the detected value is θ
In addition, the rear wheel cylinder Cr has a steering angle detector Cc (detected value θ
) is attached. The controller C has a controller C which receives the detected values from each of the detectors OA and Cc, performs arithmetic processing on the detected values based on pre-stored data, and outputs a signal to the main valve 3. Furthermore, a signal to a solenoid valve Vs2 that controls activation and inactivation of the rear wheel centering mechanism 1 disposed on the rear wheel Tr side of the vehicle is set such that the vehicle speed of the vehicle is a constant value C as indicated by the speedometer M, for example, 35 km/h), or so that it can be output manually by using a switch 57rL until the vehicle speed reaches the above-mentioned constant speed. When each of the solenoids is energized, an indicator lamp is lit to visually confirm this fact.

In this embodiment, the rear wheel cylinder Cr is formed in a so-called double rod type, and both ends of the O-rad body are connected to a connecting rod r3 that is connected to the rear wheel Tr. The hydraulic oil can be supplied from the main valve 3 into the two oil chambers partitioned on the left and right inside, or the main valve 3 can be supplied from the two oil chambers.
It is formed so that hydraulic oil can be discharged to.

The main valve 3 has the same function as the metering valve 2α in the oil supply mechanism 2 in the embodiment shown in FIG. The spool 31 has a spool 31 that can be returned to a neutral position by springs 32 disposed at both ends, and has solenoids 33 at both ends. The spool 31 is made to slide by energizing a selected one of the spools 31 to enable so-called flow path switching. Moreover, the spool 317 (has a land portion 31a on the medium heat side and land portions 31A and 31C on both ends, and each of the land portions 31α,
31J31C so that the flow of hydraulic oil can be regulated.

Also in this embodiment, the rear wheel centering mechanism 1 is constructed and operated in the same manner as in the embodiment shown in Figure 2 above.

Therefore, according to this embodiment, when the vehicle is running at low speed, the front wheels T
When the steering f is performed, the steering of the rear wheels Tr is enabled by the control by the controller C. However, the maintenance of the neutral position of the rear wheels Ty when the vehicle is running at high speed is achieved by the rear wheel centering mechanism according to the present invention. 1, it will be allowed.

In each of the embodiments shown in Figure 1 and Figure 3, the power steering mechanism PS for steering the front wheel Tf may be of any type as long as it allows the front wheel Tf to be steered by using hydraulic pressure. Of course, the oil supply mechanism 2 in the embodiment shown in FIG. The valve 2α and the metering cylinder 2b may be formed separately, and in this case, the metering valve 2α is connected to the power steering mechanism P.
It may be arranged in the control valve section of S.

〔Effect of the invention〕

As described above, according to the present invention, not only can the rear wheels be steered by following front wheel steering when a working vehicle such as a truck is turning or going diagonally at low speed, but also the rear wheels of the vehicle can be steered. When the vehicle shifts to high-speed driving, it has the advantage of being able to stop steering the rear wheels and maintain the neutral position of the rear wheels.

Further, according to the present invention, in maintaining the rear wheel neutral position,
By using spring force, there is no need to separately equip a supply device, and the hydraulic pressure used in the front and rear wheel steering devices can be reduced to only the hydraulic pressure for operating the rear wheel cylinders, making the entire device smaller and lighter. This has the advantage that it is possible to achieve

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing an embodiment of a front and rear wheel steering device equipped with a rear wheel neutralization device according to the present invention, Figure 2 is a sectional view showing a rear wheel neutralization device, and Figure 3 is the same as Figure 1. FIG. 3 is a circuit diagram showing another embodiment. 1... Rear wheel centering mechanism, 2... Oil supply mechanism, 2
a: Metering valve, 2, b: Metering cylinder, 3: Main valve, Or: Rear cylinder, H*s: Handle, L/. L-domain supply/exhaust path, PS--power steering mechanism, Tf...front wheel, Tr...rear wheel.

Claims (3)

[Claims] (1) In a rear wheel neutral device for a front-rear wheel steering vehicle that is configured to maintain a neutral position of the rear wheels that can be steered following the steering of the front wheels, a vehicle is set on the rear wheel side of the vehicle. A front and rear wheel steering vehicle is provided with a rear wheel centering mechanism configured to disable steering of the rear wheels by a spring force generated when fluid pressure is released when the vehicle speed exceeds . Rear wheel neutralization device. (2) The vehicle is formed so that the front wheels can be operated by a power steering mechanism, and a metering valve is disposed on the front wheel side of the vehicle that is operated by the handle operation for front wheel steering. Claim 1, further comprising a rear wheel cylinder provided on the rear wheel side of the vehicle to enable the rear wheels to be steered by supplying hydraulic oil from the metering valve. Rear wheel neutralization device for the vehicle with front and rear wheel steering described above. (3) A rear wheel neutralization device for a front and rear wheel steered vehicle according to claim 1, wherein the rear wheel centering mechanism is configured such that air pressure from an external air tank is supplied through a solenoid valve. .