JPH035504Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field The present invention relates to a hydraulic steering device for agricultural machinery and construction machinery that is simple and requires less horsepower to make steering operations easier in rice fields and wetlands. It is something.

(b) Prior Art Hydraulic steering devices in which a steering hydraulic cylinder is interposed between a pitman arm and a knuckle arm have been known. For example, Japanese Patent Publication No. 43-19988.

There is also a known technique in which a hydraulic pump, a hydraulic steering device, and a hydraulic device for lifting and lowering a work machine are arranged in series, and the neutral position of the steering hydraulic valve device is set in a tandem center configuration. For example, Jikko 54-6196
As per the publication No.

However, in the technology described in the above-mentioned Japanese Patent Publication No. 43-19988, since the steering handle, pitman arm, and knuckle arm are directly connected, the turning operation of the steering handle is faster than the expansion and contraction speed of the steering hydraulic cylinder. If the speed increases, the movement speed of the pressure oil into the interior of the steering hydraulic cylinder oil chamber is slow, and a negative pressure vacuum portion is generated within the oil chamber.

In addition, if the hydraulic pump malfunctions, pressure oil will not be supplied to the steering hydraulic cylinder even if you operate the steering handle to switch the steering hydraulic valve device, and even if you forcefully operate the steering handle, Since the pressure oil in the steering hydraulic cylinder is immovable, it is impossible to extend or contract at all, and the knuckle arm cannot be operated, resulting in the inconvenience that turning steering is completely impossible.

Further, in the technique described in Japanese Utility Model Publication No. 54-6196, a check valve is not arranged in parallel with the steering hydraulic valve device, so the same problem as described above occurs.

(c) Problems to be solved by the invention The present invention improves the above-mentioned defects by interposing a check valve in parallel with the steering hydraulic valve device.

In addition, by making the steering hydraulic valve device an open center type, the increase in pressure in the hydraulic device for lifting and lowering the work equipment will affect the steering hydraulic cylinder. This is a tandem center type hydraulic valve device.

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

In a configuration in which pressurized oil discharged from one hydraulic pump 23 is supplied to a hydraulic steering device and a hydraulic device for lifting and lowering work equipment arranged in series, and both can be operated simultaneously, the pitman arm 3 of the steering handle 2, A steering hydraulic valve device A is interposed between the knuckle arm operating member and a steering hydraulic cylinder 8 is interposed between the knuckle arm operating member and the fuselage frame 16.
The neutral position of the steering wheel is of a tandem center type, and a check valve 6 is installed in parallel with the steering hydraulic valve device A.

(E) Embodiment The problems to be solved by the present invention and the means for solving them are as described above.Next, the structure of the embodiment shown in the attached drawings will be explained.

Fig. 1 is an overall side view of a riding rice transplanter equipped with the hydraulic steering device of the present invention, Fig. 2 is a hydraulic circuit diagram of the hydraulic steering device of the present invention, and Fig. 3 is a plan view of the hydraulic valve device. , Fig. 4 is a side sectional view, Fig. 5 is a circuit diagram of the tandem center type hydraulic valve device shown in Fig. 4, and Fig. 6 is a hydraulic diagram of a hydraulic valve device equipped with a throttle circuit to prevent shock and over-cutting. It is a circuit diagram.

Let me explain about Figure 1.

The hydraulic steering device of the present invention includes a hydraulic valve device A between a pitman arm 3 that is rotated back and forth by a steering handle 2 and a bell crank arm 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 of the bell crank arm 4 and the fuselage frame 16.

Therefore, the hydraulic valve device A is of course switched by the rotation of the steering handle 2, but also by the expansion and contraction of the hydraulic cylinder 8 via the bell crank arm 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 is composed of a relief valve 7 and a check valve 6. The pressure oil spouted from the relief valve device is configured to be sent to the hydraulic device 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.
This connects a and 8b.

The action of this check valve 6 is that the hydraulic port is stopped and no pressure oil is sent, so when the operator manually pushes or pulls the drag rod, the check valve 6 opens and the steering hydraulic cylinder 8
By communicating the hydraulic pressures 8a and 8b, manual steering is possible even when no pressure oil is generated.

What makes manual steering possible is that in addition to the check valve 6, a hydraulic valve device A is directly connected and interposed 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 through the piping 18, and enters the oil chamber 8a of the hydraulic cylinder 8.
The pressure oil b reaches the hydraulic system for lifting and lowering the work 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.

In the overall configuration as described above, if the hydraulic valve device is an open center type, the P, T, E, and F ports will be connected in the neutral state, so the front and rear chambers of the hydraulic cylinder 8, It communicates with the hydraulic system C for raising and lowering the work equipment, and when a load is applied when raising the work equipment, the pressure in the pipings 17 and 18 increases, and a difference in pressurized area occurs depending on the presence or absence of the piston rod of the hydraulic cylinder 8. It moves to.

This caused problems such as the front wheels moving or moving momentarily when the machine was moved up and down while driving.

In order to eliminate this problem, the present invention uses a tandem center type hydraulic valve device A, and when in neutral, P.
By cutting off the T port and the E/F ports, the influence of the operation of the hydraulic system C for lifting and lowering the working machine is not transmitted.

That is, since the 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, E and F The port and the P/T port were cut off. However, since the P port and the T port are connected, pressure oil flows from there to the hydraulic system C for lifting and lowering the working machine.

When the hydraulic valve device is in the switching position a or b, the pressure oil in the chamber opposite to the chamber into which the pressure oil is fed is pushed out and flows to the hydraulic device for lifting and lowering the working machine. Further, after the hydraulic cylinder 8 is expanded and contracted to the maximum extent, the relief valve 7 blows out, and the pressure oil that blows out from here reaches the hydraulic system for lifting and lowering the working machine.

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.

The hydraulic valve device A shown in FIGS. 2 and 5 shows a typical configuration of a tandem center type three-position control valve, but the hydraulic valve device A shown in FIG.
A' shows an embodiment in which the feeling does not change when the steering wheel is turned, both at idling speed and at maximum engine speed.
This prevents the shortcomings of the tandem center type, such as shock when switching the handle, excessive cutting, and shimmy.

That is, the spool is provided with a throttle groove that allows excess pump flow to escape into the tank during the transition period when switching from neutral to a/b states. This configuration provides an improvement.

(f) Effects of the invention Since the invention is constructed as described above, it has the following effects.

First, because the hydraulic pump, the hydraulic traveling device, and the hydraulic device for raising and lowering the work equipment were arranged in series, the hydraulic pump could be made smaller and only one, and the required horsepower could be reduced.

Second, even though both were placed in series and operated with the same pressure oil, it was a tandem center system.
Since the relationship between the two can be severed when the machine is in neutral, it is no longer possible for the steering wheel to experience shock or for the steering wheel to rotate naturally as the work equipment moves up and down.

Thirdly, by arranging the check valve 6 in parallel with the steering hydraulic valve device A, even when pressure oil is not supplied by the hydraulic pump 23, the steering can be performed manually by rotating the steering handle 2. By moving the hydraulic valve device A and operating the knuckle arm 9, it was possible to perform turning steering.

[Brief explanation of drawings]

Fig. 1 is an overall side view of a riding rice transplanter equipped with the hydraulic steering device of the present invention, Fig. 2 is a hydraulic circuit diagram of the hydraulic steering device of the present invention, and Fig. 3 is a plan view of the hydraulic valve device. , Fig. 4 is a side sectional view, Fig. 5 is a circuit diagram of the tandem center type hydraulic valve device shown in Fig. 4, and Fig. 6 is a hydraulic circuit of a hydraulic valve device equipped with a throttle circuit to prevent shock, over-cutting, and shimmy. It is a diagram. A...Hydraulic valve device for steering, B...Combination valve device, C...Hydraulic device for lifting and lowering the working machine, 4...Bell crank arm (knuckle arm operating member), 22...Hydraulic pump.

Claims (1)

[Scope of utility model registration request] In a configuration in which pressurized oil discharged from one hydraulic pump 23 is supplied to a hydraulic steering device and a hydraulic device for lifting and lowering work equipment arranged in series, and both can be operated simultaneously, the pitman arm 3 of the steering handle 2, A steering hydraulic valve device A is interposed between the knuckle arm operating member and a steering hydraulic cylinder 8 is interposed between the knuckle arm operating member and the fuselage frame 16.
A hydraulic steering device characterized in that the neutral position of the steering valve device A is of a tandem center type, and a check valve 6 is interposed in parallel with the steering hydraulic valve device A.