JPH0356685B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a hydraulic steering device for a vehicle such as a four-wheeled agricultural machine.

(b) Prior Art Agricultural machinery and construction machinery have heavy handles because they are repeatedly driven through rice paddies, muddy wetlands, etc., making them tiring to work with for long periods of time.

Therefore, it is necessary to install a hydraulic steering device, but if you use a hydraulic steering device, you will need to install an additional hydraulic pump and hydraulic oil tank, or if you want to use one hydraulic pump for both purposes, you will need a flow divider. It was necessary to establish a

For example, Japanese Patent Application Laid-Open No. 56-60770.

(c) Problems to be solved by the invention As mentioned above, hydraulic steering devices have been available in the past, but it is necessary to install two hydraulic pumps together with one for lifting and lowering the work, and one If you try to use a hydraulic pump for both, there is a problem that unless you use a flow divider to divide the flow at a constant pressure, both hydraulic systems will have an adverse effect on each other.As a result, a large amount of power is required for the hydraulic system, and a small 4-wheel The problem was that it could not be installed on a moving vehicle.

In order to solve this problem, the present invention uses only one hydraulic pump for both hydraulic devices, passes the pressure oil from the hydraulic pump in series between the steering device and the work equipment lifting device, and eliminates the flow divider. It requires less power.

(d) Means for solving the problem The purpose of the present invention is as described above. Next, the configuration for achieving the purpose will be explained.

In a four-wheeled vehicle equipped with a hydraulic steering device and a hydraulic device C for elevating work equipment, pressure oil from a hydraulic pump 23 driven by an engine is supplied to a hydraulic valve device A of the hydraulic steering device and a hydraulic cylinder device. 8
Oil is sent in series to the hydraulic valve device 26 and the hydraulic cylinder device 25 of the hydraulic device C for lifting and lowering the working machine.

Furthermore, a bypass with a pressure regulating relief valve 7 interposed therein is provided in parallel with the hydraulic valve device A, the hydraulic cylinder device 8, etc. of the hydraulic steering system.

(e) Embodiments and operations The purpose and structure of the present invention are as described above, and the structure and operations of the embodiments shown in the attached drawings will now be explained.

FIG. 1 is an overall side view of a riding type rice transplanter among agricultural machinery in which the steering device of the present invention is attached. FIG. 2 is a hydraulic circuit diagram of the steering device of the present invention. Figures 3 and 4
5 and 6 are plan views of an integrated open center type hydraulic valve device A and a combination valve device B. Side sectional view. Front sectional view. Hydraulic circuit diagram. 7 and 8 are a side sectional view and a hydraulic circuit diagram of a tandem center type hydraulic valve device.

The hydraulic valve device can be of an open center type as shown in Figs.
It is also possible to use a tandem center system as shown in Figs. It has some effect.

In FIG. 1, the hydraulic steering device of the present invention is
A hydraulic valve device A is interposed between a pitman arm 3 that is rotated back and forth by a steering handle 2 and a bell crank 4 that is a knuckle arm operating member that is pivotally supported on the front axle. A hydraulic cylinder 8 for steering is interposed between one end and the fuselage frame 16. Therefore, the hydraulic valve device A is of course switched by the rotation of the steering handle, but also by the expansion and contraction of the hydraulic cylinder 8 via the bell crank 4.

In FIG. 2, the hydraulic circuit configuration will be explained first. 23 is a hydraulic pump. The hydraulic pump 23
is attached to the side of the driving engine E of the traveling vehicle, which sucks the lubricating oil in the transmission case of the machine body as hydraulic oil and discharges it as pressure oil, and drives the hydraulic steering device and the hydraulic device for lifting and lowering the work equipment. Pressure oil is supplied to both devices in C. The pressure oil discharged from the hydraulic pump 23 is sent via a combination valve device B to a hydraulic valve device A for a hydraulic steering device. The combination valve device includes a pressure regulating relief valve 7 and a check valve device 6.
It is composed of. The pressure oil spouted from the pressure regulating relief valve device is configured to be sent to the hydraulic system C for lifting and lowering the working machine. The combination valve device B can also be integrally constructed near the hydraulic port P of the hydraulic valve device as shown in FIGS. 3, 4, and 5.

Further, the return oil after passing through the hydraulic valve device A is also configured to join together and be sent as pressure oil for lifting and lowering the working machine. Furthermore, the check valve 6 provided in the combination valve device B creates a vacuum inside the hydraulic cylinder 8 when the speed at which the operator pushes and pulls the drag rods 11 and 13 is faster than the expansion and contraction speed of the hydraulic cylinder 8. In order to prevent cavitation, the check valve 6 is opened and the oil chamber 8 of the hydraulic cylinder is opened.
a and 8b.

Since the hydraulic pump stops and no pressure oil is sent, the check valve 6 acts in the same way when the operator manually pushes or pulls the drag rod. Even when no pressure oil is generated, the check valve 6 operates in the same way This is possible.

What makes manual steering possible is that, in addition to the check valve 6, a hydraulic valve device A is directly connected between the drag rods 11 and 13.

The hydraulic valve device A is composed of a valve case 5 and a spool 22, and drag rods 11 and 13 are directly connected to the front and rear of these. Therefore, when the drag rod 13 is pushed or pulled through the steering gear box 20 and the pitman arm 3 by rotation of the steering handle 2, the spool 22 integrally attached thereto is pushed or pulled, and is further integrated into the valve case 5. The dragged drag rod 11 is pushed and pulled.

When the steering handle 2 is rotated, the Pittman arm 3 is moved backward, and the spool 22 is moved against the spring 14, the valve port is
Pressure oil flows into the oil chamber 8b of the hydraulic cylinder 8 via the piping 17, and the pressure oil is sent to the oil chamber 8a toward the hydraulic device C for lifting and lowering the work equipment. . At this time, if the rotation of the pitman arm 3 is faster than the expansion and contraction of the hydraulic cylinder 8, the check valve 6 is opened and the front and rear oil chambers 8a, 8b are communicated with each other so that a vacuum condition does not occur.

Also, when the Pittoman arm 3 is rotated forward,
The spool 22 moves and the valve port is switched to b. Then, the pressure oil enters the oil chamber 8a of the hydraulic cylinder 8 via the piping 18, and the pressure oil in the oil chamber 8b reaches the hydraulic system for lifting and lowering the working machine. 4 is a bell crank arm, which is a member for operating the knuckle arm 9. A piston rod 12 of a hydraulic cylinder 8 and a drag rod 11 with a valve case 5 interposed therebetween are pivotally connected to one end of the bell crank arm, and left and right tie rods 10L and 10R are connected to the other end.

Knuckle arms 9L, 9R are rotated by tie rods 10L, 10R, and front wheels 1L, 1R are rotated. Although the bell crank arm 4 is provided in this embodiment, the bell crank arm 4 may be directly used as one of the knuckle arms.

Also, since a biasing spring 14 is interposed between the spool 22 and the valve case 5, the valve port is always biased toward the neutral position, and when the hydraulic valve device is in the neutral position, the valve port is biased through the neutral port. Pressure oil is sent directly to the hydraulic system C for the work machine, and after the hydraulic valve expands and contracts the hydraulic cylinder as much as possible at port a or b, the pressure oil squirted out from the pressure regulating relief valve 7 is sent to the hydraulic system C. Immediately after the valve ports are switched to a and b, the pressure oil in the other oil chamber is blown out from the pressure regulating relief valve 7 and reaches the hydraulic device C.

When lifting and lowering the work equipment, if a load is applied to the hydraulic cylinder for lifting and lowering, the piping 17, 1
The pressure in the hydraulic cylinder 8 increases, and the hydraulic cylinder 8 moves in the direction of extension due to the area difference between the presence and absence of the piston rod, but this movement also moves the valve case 5, causing the valve port to change pressure from neutral to oil chamber 8b. Since the oil is automatically switched to the inflow direction a, a force is applied in the direction of contracting the hydraulic cylinder, and the balance is no longer affected by the presence or absence of a load on the hydraulic system C.

In FIG. 4, 28 is a pin that connects the drag rod 11 and the valve case 5. The pin 2
8 also fits into the elongated hole 22a of the spool 22, and also serves as a stopper to prevent the spool from moving beyond the switching sliding width.

As shown in the above overall configuration, the present invention connects the hydraulic pump 23, the hydraulic valve device A of the hydraulic steering device, the hydraulic cylinder device 8, and the hydraulic device C for lifting and lowering the work machine to the hydraulic valve device 26 and the hydraulic cylinder 25 in series. It is arranged in .

Further, a bypass with a pressure regulating relief valve 7 interposed therein is provided in parallel with the hydraulic steering device.
By arranging the two devices in series, the pressure oil acts entirely on each device, making it possible to drive both devices with a small amount of pressure oil. As a result, both devices can be driven by a pump with lower horsepower than the conventional two-pump type or flow divider type.

In addition, since a pressure regulating relief valve is installed in parallel with the hydraulic valve device A of the hydraulic steering device, the hydraulic cylinder 8 expands and contracts as much as possible while the hydraulic valve device A remains in the a position or the b position, and the pressure oil is released. Even when the oil is spouted from the relief valve, in a normal hydraulic circuit, the jetted oil from the relief valve is returned to the hydraulic oil tank, but in the present invention, this jetted oil is directed to the hydraulic system C for lifting and lowering the work equipment. By using this as pressure oil, it is possible to arrange both devices in series.

Next, the case of the open center method shown in FIGS. 3 to 6 will be explained.

Even if the steering handle 2 is fixed and the hydraulic valve device for steering is in the neutral position, if the hydraulic valve device is an open center type, pressure oil will be released based on the operation of the hydraulic device C for lifting and lowering the work equipment. This acts on the steering hydraulic cylinder 8,
Since the piston rod is on one side, there is a problem in that the hydraulic cylinder 8 expands due to the difference in the area of action of the front and rear pistons.

In this case, the extension of the hydraulic cylinder 8 operates the hydraulic valve device A via the bell crank 4,
Since it switches to the direction where it will not extend any further, it will be balanced at that position and the natural extension that occurs because the hydraulic cylinder is open center will stop here.

On the other hand, if the hydraulic valve device A is of a tandem center type as shown in FIGS. 7 and 8, it will not be affected by the pressure of the hydraulic device C for lifting and lowering the working machine when the hydraulic valve device is in the neutral state. Although this point is an advantage, the following disadvantages also occur. In other words, since the pressure oil is not at a constant pressure with the constant pressure type flow divider, and because the pressure oil cannot be throttled with the spool, the steering feeling when turning the steering wheel 2 is different between the idling rotation of the engine and the maximum rotation. They are different.

Furthermore, when the feeling is adjusted to the idling rotation, shock or excessive jerking occurs when the steering wheel is operated at maximum rotation.

As described above, open centers and tandem centers each have their own advantages and disadvantages.

(F) Effects of the Invention Since the present invention is constructed as described above, it exhibits the following effects.

First, the hydraulic pump can be used as a small hydraulic pump to sufficiently operate both hydraulic systems, and compared to the conventional flow divider type or two-pump type hydraulic steering system, it is suitable for vehicles with low horsepower engines. It can also be used in

Second, the hydraulic valve device and the hydraulic cylinder device can be arranged compactly and the hydraulic steering device can be constructed at low cost.

[Brief explanation of drawings]

FIG. 1 is an overall side view of a riding type rice transplanter among agricultural machinery in which the steering device of the present invention is attached. FIG. 2 is a hydraulic circuit diagram of the steering device of the present invention. Figures 3 and 4
Figures 5 and 6 show an open center type hydraulic valve device A and a combination valve device B.
A plan view of an integrated structure. Side sectional view.
Front sectional view. Hydraulic circuit diagram. 7 and 8 are a side sectional view and a hydraulic circuit diagram of a tandem center type hydraulic valve device A'. A, A'...Hydraulic valve device, B...Combination valve device, C...Hydraulic device for lifting and lowering work equipment, 4...Bell crank arm, 6...Check valve, 7...Pressure regulation relief valve, 8 ... Hydraulic cylinder device, 25 ... Hydraulic cylinder, 26
...Hydraulic valve device.

Claims (1)

[Scope of Claims] 1. In a four-wheeled vehicle equipped with a hydraulic steering device and a hydraulic device C for lifting and lowering work equipment, pressure oil from a hydraulic pump 23 driven by an engine E is supplied to the hydraulic steering device. A hydraulic traveling device characterized in that oil is fed in series to a hydraulic valve device 26 and a hydraulic cylinder 25 of a hydraulic device C for lifting and lowering a working machine via a hydraulic valve device A, a hydraulic cylinder device 8, and the like. 2. In the hydraulic traveling device according to claim 1, the hydraulic valve device A of the hydraulic steering device;
A hydraulic steering device characterized in that a bypass in which a pressure regulating relief valve 7 is interposed is provided in parallel with a hydraulic cylinder device 8 and the like.