JPH03125670A - Rear wheel steering device - Google Patents

Abstract

PURPOSE:To enable the heat exchange of both heating values of a pressurizing system hydraulic circuit and a static pressure system hydraulic circuit and improve steering performance by providing a fluid chamber in part of the fluid passage of either of the circuits, and interposing a part of the fluid passage of the other circuit in the fluid chamber. CONSTITUTION:A rear wheel steering device has a pressurizing system hydraulic circuit 16 formed by connecting together a pump 10, a power cylinder 13, a pressure control valve 11 for controlling the feed and discharge of a pressurized fluid to the power cylinder 13, and a tank 15 by pipelines L1, L4, L5. Also, a static pressure system hydraulic circuit 22 formed by connecting a meter ring cylinder 21 interlocked with a steering gear mechanism 17 for steering a front wheels 20 by the steering force of a steering handle 18 to a pilot cylinder 14 for controlling the spool valve 11b of the pressure control valve 11 by pipelines L6, L7 is provided. In this case, a heat exchanging part 23 extending through the pipelines L6, L7 is provided in a fluid chamber 23b to which the pipelines L4, L5 are connected to suppress a temperature rise of the pressurized fluid in the pressurizing system hydraulic circuit 16.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a rear wheel steering device applied to a four-wheel steering vehicle, and particularly to a rear wheel steering device that obtains front wheel steering information via a static pressure system circuit. It relates to a wheel steering device.

(Prior art) As a conventional rear wheel steering device of this type, for example,
There is an apparatus described in Japanese Patent No. 0-45266, which is shown in FIG.

This conventional device includes a pump l that discharges fluid pressurized to a predetermined pressure (hereinafter referred to as pressurized fluid P+), a pressure control valve 2 whose position of a valve body 2a changes depending on the rear wheel steering angle, and a rear wheel A power cylinder 3 for manipulating the steering angle; and a metering cylinder 5 that includes a pressurizing hydraulic circuit 4 and discharging an amount of fluid (hereinafter referred to as static pressure fluid P2) according to the front wheel steering angle; A pilot cylinder 6 that adjusts the position of the spool valve 2b of the pressure control valve 2 in response to P2; The spool valve 2b changes its position according to the rear wheel steering angle, and the pressurized fluid supplied to the power cylinder 3 is controlled so that these positional relationships are balanced.

(Problem to be Solved by the Invention) However, in such a conventional rear wheel steering device, the hydraulic piping for the pressure system hydraulic circuit 4 and the static pressure system hydraulic circuit 7 are laid in separate systems. This caused problems such as insufficient rear wheel steering angle and difficult steering operation due to the difference in heat generation between the two hydraulic circuits.

In other words, in general, the total amount of heat generated in a hydraulic circuit HT is calculated by the following formula ■
It is expressed as

Hy =H+ +H2+Hx ・・・・・・■Here, Hl is the amount of heat generated due to power loss of the pump, etc., H2
is the amount of heat generated when the flow returns to the tank via a relief valve or throttle valve, etc.; H3 is the thickness of the piping, changes in the cross-sectional area of bent branch pipes, oil leaks, fluid flow in the pipes, pressure loss due to friction, and It is the amount of heat generated due to pressure loss in valves, etc., and it is known that among them, ■(, (amount of heat generated due to power loss in pumps, etc.)) accounts for a large proportion.

Therefore, since the pressure system hydraulic circuit 4 includes the pump 1 in its configuration, the amount of heat generated is large, whereas the amount of heat generated in the static pressure system hydraulic circuit 7, which does not include a power source such as a pump, is small. , the fluid temperatures in both hydraulic circuits will be different. As a result, the following inconveniences occurred.

The fluid temperature in the pressure system hydraulic circuit 4 is high even in normal times for the reasons mentioned above, but especially in the high-temperature environment of summer, the fluid temperature rises further and the pump efficiency further decreases. Therefore, the operating power of the power cylinder 3 decreases, resulting in an insufficient actual rear wheel control steering angle relative to the desired rear wheel steering angle, resulting in a disadvantage that the turning performance of the vehicle changes.

On the other hand, although there is no concern that the temperature of the working fluid in the hydrostatic hydraulic circuit 7 will increase, there is a problem of the fluid becoming highly viscous in a low temperature environment during winter, for example. That is, when the viscosity of the working fluid in the hydrostatic hydraulic circuit 7 increases, the hydrostatic hydraulic circuit 7 acts as a load on the steering wheel operation, which causes problems such as making the steering wheel operation difficult.

Therefore, an object of the present invention is to solve both the above disadvantages (1) and (2) by performing heat exchange between the pressure system hydraulic circuit and the static pressure system hydraulic circuit.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides fluid pressurized by a pump in which the position of either the valve body or the spool valve changes in accordance with the rear wheel steering angle. It is equipped with a pressurized hydraulic circuit that supplies fluid to the power cylinder for controlling the rear wheel steering angle via a pressure control valve and then returns to the tank, and also supplies the pilot with an amount of fluid according to the front wheel steering angle from the metering cylinder. A rear wheel steering system comprising a hydrostatic hydraulic circuit that supplies water to a metering cylinder, changes the position of either the valve body of the pressure control valve or the spool valve by the pilot cylinder, and then returns the flow to the metering cylinder. A fluid chamber is provided in a part of the fluid path of one of the pressure system hydraulic circuit or the static pressure system hydraulic circuit, and a part of the fluid system of the other circuit is interposed within the fluid chamber. shall be.

(Function) In the present invention, the amount of heat in both the pressurized hydraulic circuit and the static pressure hydraulic circuit is exchanged within the fluid chamber.

Therefore, heat is transferred from the pressure system hydraulic circuit to the static pressure system hydraulic circuit, and the fluid temperature in the pressure system hydraulic circuit is lowered, thereby solving the above-mentioned disadvantage (2) in a high temperature environment. Furthermore, the above-mentioned disadvantage (2) in a low-temperature environment is solved by increasing the fluid temperature of the hydrostatic hydraulic circuit.

(Example) Hereinafter, the present invention will be explained based on the drawings.

1 to 3 are diagrams showing an embodiment of a rear wheel steering device according to the present invention.

In FIG. 1, 10 is a pump that discharges fluid pressurized to a predetermined pressure (hereinafter referred to as pressurized fluid P1), and 11 is a valve body 11a (or a spool valve 11b) that is connected to a rear wheel.
This is a pressure control valve that is integrally connected to the piston rod 13a of the power cylinder 13 for steering the engine.
a) is integrally connected to the piston rod 14a of the pilot cylinder 14. In addition, 15 is a tank, L
1 to L are pipelines forming a fluid system path, and a pump 10, a pressure control valve 11, a power cylinder 13, a tank 15, and L1 to L constitute a pressurization system hydraulic circuit 16.

On the other hand, 17 is a steering gear mechanism, and the steering gear mechanism 17 converts the steering force input to the steering wheel 18 into movement of the steering rod 19 in the vehicle width direction.
The front wheels 20 are steered. The steering rod 19 of the steering gear mechanism 17 is integrally connected to the piston rod 21a of the metering cylinder 21, and the case 21b of the metering cylinder 21 is connected to the steering gear mechanism 17.
Case 17a is identified. Note that L6, L are pipes as fluid lines, and Lh, Ll, the metering cylinder 21, and the above-mentioned biloft cylinder 14 constitute a hydrostatic hydraulic circuit 22.

Here, 23 is a heat exchange section, and a specific configuration example of the heat exchange section 23 is shown in FIG. In FIG. 2, the heat exchange section 23 has a fluid chamber 23b inside a case body 23a, an input boat 23c and an output port 23.1 are provided at both ends of the case body 23a in the longitudinal direction, and the input boat 23C has the above-mentioned structure. 4 is connected to the output port 23d, and the L is connected to the output port 23d.
6, L? Insert and configure.

With this configuration, the pressurized fluid of the pressurized hydraulic circuit I6 flowing from the input boat 23c passes through the case body 23a and then flows back to the tank 15 from the output port 23d. is the static pressure system hydraulic circuit 22 glue,
It flows while touching the pipe wall of L7. Therefore, smooth heat exchange is performed between the pressurized fluid in the pressurizing hydraulic circuit 16, which is in a relatively high temperature state due to the amount of heat generated by the pump 10, and the fluid in the static pressure hydraulic circuit 22, which is in a low temperature state. In addition, since heat exchange is also performed with the outer peripheral atmosphere of the case body 23a, the temperature of the pressurized fluid on the temperature storage side decreases and the temperature of the static pressure fluid on the low temperature side increases, resulting in a decrease in the temperature of both fluids. Temperatures approach or balance.

This makes it possible to solve the above-mentioned disadvantage (2) in a high-temperature environment, and also to solve the above-mentioned disadvantage (2) in a low-temperature environment.

Note that the configuration of the heat exchange section is not limited to the example shown in FIG. 2; for example, as shown in another embodiment in FIG. 3, several case bodies (in the example, three case bodies A, B, C)
are connected by pipes La and Lb, and the pipes, L, of the pressure system hydraulic circuit 16 are connected to the case bodies A and C at both ends, and the static pressure system is connected inside the case bodies A, B, and C. The pipes L6 and L7 of the hydraulic circuit 22 may be inserted therethrough. Heat exchange efficiency can be easily improved by increasing the number of case bodies. Furthermore, since each case body can be arranged flexibly, the mountability on a vehicle is improved.

Furthermore, each of the above-mentioned heat exchange parts is mounted on the case body between the glue and the groove of the pressure system hydraulic circuit 16, that is, the position closest to the tank 15, but the pressure system hydraulic circuit 1
Considering that the pump 10 accounts for a considerable proportion of the heat generated by the pump 6, it is not limited to the above-mentioned mounting position, but can be mounted anywhere on the fluid system between the pump 10 and the tank 15. However, the desired heat exchange function can be achieved.

(Effects) According to the present invention, since heat exchange is performed between the pressurized hydraulic circuit and the static pressure hydraulic circuit, the problem of insufficient rear wheel steering angle in a high temperature environment (disadvantages mentioned above) ) and the problem that the steering wheel becomes difficult to operate in a low-temperature environment (the above-mentioned problem) can be solved together.

[Brief explanation of the drawing]

1 to 3 are diagrams showing one embodiment of the rear wheel steering device according to the present invention, in which FIG. 1 is a system configuration diagram thereof, FIG. 2 is a configuration diagram of an example of its heat exchange section, and FIG. 4 is a configuration diagram of another example of the heat exchange section, and FIG. 4 is a system configuration diagram of a conventional example. 10...Pump, 11...Pressure control valve, 11a...Valve body, 11b...Spool valve, Work 3...Power cylinder , 13a... Piston rod, 14... Pilot cylinder, 14a...
... Piston rod, 15 ... Tank, 16 ... Pressure system hydraulic circuit, 21 ... Metering cylinder, 21a ...
... Piston rod, 2i ... Case, 22 ... Static pressure system hydraulic circuit, 23 ... Heat exchange section, 23a ... Case body, 23b ...Fluid chamber.

Claims (1)

[Claims] Fluid pressurized by a pump is passed through a pressure control valve in which the position of either the valve body or the spool valve changes in accordance with the rear wheel steering angle to generate power for controlling the rear wheel steering angle. A pressurizing system hydraulic circuit is provided which supplies fluid to the cylinder and then returns to the tank, and supplies an amount of fluid from the metering cylinder to a pilot cylinder according to the front wheel steering angle, and the pilot cylinder uses the valve of the pressure control valve. In a rear wheel steering device equipped with a hydrostatic hydraulic circuit that returns the flow to the metering cylinder after changing the position of the other of the main body and the spool valve, one of the pressurizing hydraulic circuit or the static hydraulic circuit A rear wheel steering device characterized in that a fluid chamber is provided in a part of a fluid system path of a circuit, and a part of a fluid system path of the other circuit is interposed in the fluid chamber.