JPH0248291Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a hydraulic steering device for riding agricultural machinery etc. equipped with a small horsepower engine.

(b) Prior Art A hydraulic steering device called power steering has been well known.

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

However, the conventional technology described above requires the use of separate hydraulic pumps for the hydraulic steering system and for raising and lowering the work equipment, which has the disadvantage that it cannot be used with rice transplanters etc. that have low engine horsepower. It is.

(c) Problems that the invention aims to solve The purpose of this invention is to use one small pump for raising and lowering the working machine and for the hydraulic steering device, so that it can be used even with rice transplanters with small engine horsepower. This made it possible.

A single hydraulic pump like this provides a steering device and
In order to drive the work equipment lifting device, it is necessary to configure the system so that switching the hydraulic control valve or increasing pressure to operate one device will not cause the other hydraulic cylinder to expand or contract or cause a shock. Conventionally, a flow divider was used to divide the flow at a constant rate so as not to affect the pressure oil on the other side.

However, even in this case, a large-capacity hydraulic pump had to be driven, which required a large horsepower engine.

In the present invention, the pressure oil of the hydraulic pump is configured to flow in series to the steering device and the work equipment lifting device.

In addition, in order to configure as described above, it is necessary to arrange the steering hydraulic valve device and the steering hydraulic cylinder in series, and at this time, the steering valve is pushed or pulled faster than the expansion and contraction of the hydraulic cylinder. The structure is such that negative pressure does not occur within the hydraulic cylinder.

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

In a configuration in which a steering hydraulic valve device A is interposed between the pitman arm and 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 pump 23, the steering hydraulic valve device A and the working machine lifting hydraulic device C are arranged in series to send pressure oil, and the steering hydraulic valve device A and the steering hydraulic cylinder 8 are arranged in parallel to The suction valve 6, which opens in response to pressure, is connected to a high-pressure oil path from the pressure oil pump 23 to the steering hydraulic valve device A, and an oil path from the steering hydraulic valve device A to the hydraulic device C for lifting and lowering the work equipment. It is interposed between.

(E) Embodiments and operations The purpose of the present invention is as described above, and the operations of the invention will be explained in conjunction with the configuration of the embodiments shown in the attached drawings.

Figure 1 is an overall side view of a riding rice transplanter equipped with the hydraulic steering device of the present invention, Figure 2 is a hydraulic circuit diagram of the hydraulic steering device of the present invention, and Figure 3 is an open center type hydraulic valve. A plan view of the device, FIG. 4 is a side sectional view, and FIG. 5 is a view taken along line M-M in FIG. 3.
FIG. 6 is a circuit diagram of an open center type hydraulic valve device, FIG. 7 is a side sectional view of a tandem center type hydraulic valve device, and FIG. 8 is a hydraulic circuit diagram of a tandem center type hydraulic valve device.

The outline will be explained with reference to FIG.

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 arm 4 on the front axle. Further, a steering hydraulic cylinder 8 is interposed between the other end of the bell crank arm 4 and the fuselage frame 16. The bell crank arm 4 is a knuckle arm operating member.

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, and sucks the lubricating oil in the transmission case of the machine body as hydraulic oil and discharges it as pressure oil, and uses the hydraulic steering system and the hydraulic pressure for lifting and lowering the work equipment. Pressure oil is supplied to both devices of device 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 pressure-hydraulic steering device. The combination valve device is composed of a relief valve 7 and a suction 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. Combination valve device B
It is also possible to integrally configure it 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 suction 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. Then,
To prevent cavitation from occurring,
The suction valve 6 opens to communicate the oil chambers 8a and 8b of the hydraulic cylinder.

The action of this suction valve 6 is the same when the operator manually pushes and pulls the drag rod when the hydraulic pump is stopped and no pressure oil is sent, and even when no pressure oil is generated, the suction valve 6 can be operated manually. This is possible.

In addition to this suction valve 6, what makes manual steering possible is the hydraulic valve device A.
This is also due to the fact that the drag rods 11 and 13 are directly connected to each other.

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.

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 b of the hydraulic cylinder 8 via the piping 17, and the pressure oil in the oil chamber 8a is sent to 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, a vacuum state will occur, so the suction valve 6 will open and the front and rear oil chambers 8 will open to prevent a vacuum state from occurring.
A and 8b are made to communicate with each other.

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 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 drag rod 11 having a piston rod 12 of a hydraulic cylinder 8 and a valve case 5 interposed therebetween is 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 device C for lifting and lowering the work equipment, and after the hydraulic valve expands and contracts the hydraulic cylinder as much as possible at port a or b, the pressure oil spouted from the relief valve 7 is sent to the hydraulic device C. Immediately after the valve ports are switched to a and b, the pressure oil in the other oil chamber reaches the hydraulic system 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 inside the hydraulic cylinder 8 increases, and the hydraulic cylinder 8 moves in the direction in which it extends due to the difference in area between the piston rod and the piston rod.

Due to this movement, the valve case 5 is also moved, and the valve case is automatically switched from neutral to the direction a in which pressure oil flows into the oil chamber 8b, so a force is applied in the direction of contracting the hydraulic cylinder, and the balance is maintained. This means that it is not 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 2, and also serves as a stopper to prevent the spool from moving beyond the switching sliding width.

2 to 6 show the case where the hydraulic valve device A is of an open center type, but in this case, as described above, it is susceptible to the influence of the hydraulic device C for lifting and lowering the working machine.

Therefore, in the case of FIGS. 7 and 8, this problem is solved by making the hydraulic valve device A' a tandem center type.

In other words, if the hydraulic valve device is of the tandem center type, the P/I ports and the E/F ports will be cut off in the neutral state, and the hydraulic device C for lifting and lowering the work equipment will be disconnected.
The impact of this is not conveyed.

However, since the P port and the I 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 A' 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 is ejected, and the pressure oil reaches the hydraulic system for lifting and lowering the working machine from here.

In the overall configuration as described above, the present invention is provided with a suction valve 6 that opens in response to the negative pressure of the steering hydraulic cylinder in parallel with the steering hydraulic system.

(F) Effects of the invention The structure of the present invention is as described above, and this structure produces the following effects.

First, although it is a hydraulic steering system, manual steering is possible by operating the hydraulic valve system A like a rod in the event of an unexpected failure of the engine or hydraulic pump.

That is, if the suction valve 6 were not present, the hydraulic cylinder 8 would be under negative pressure, making manual steering impossible.

Second, even when hydraulic steering is normally being carried out, it is possible to turn the steering wheel faster than the expansion and contraction speed of the hydraulic cylinder and quickly perform semi-manual steering, allowing hydraulic steering to be used in response to immediate danger. Even in cases where speed cannot be used, it is now possible to respond by manual steering.

[Brief explanation of the drawing]

Figure 1 is an overall side view of a riding rice transplanter equipped with the hydraulic steering device of the present invention, Figure 2 is a hydraulic circuit diagram of the hydraulic steering device of the present invention, and Figure 3 is an open center type hydraulic valve. A plan view of the device, FIG. 4 is a side sectional view, and FIG. 5 is a view taken along line M-M in FIG. 3.
FIG. 6 is a circuit diagram of an open center type hydraulic valve device, FIG. 7 is a side sectional view of a tandem center type hydraulic valve device, and FIG. 8 is a hydraulic circuit diagram of a tandem center type hydraulic valve device. A, A'...Hydraulic valve device, C...Hydraulic device for lifting and lowering work equipment, 2...Steering handle, 3
... Pitman arm, 4 ... Bell crank arm, 5 ... Valve case, 6 ... Suction valve, 7 ... Relief valve, 8 ... Hydraulic cylinder, 9 ... Katsukuru arm.

Claims (1)

[Scope of utility model registration request] In a configuration in which a steering hydraulic valve device A is interposed between the pitman arm and 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 pump 23, the steering hydraulic valve device A and the working machine lifting hydraulic device C are arranged in series to send pressure oil, and the steering hydraulic valve device A and the steering hydraulic cylinder 8 are arranged in parallel to The suction valve 6, which opens in response to pressure, is connected to a high-pressure oil path from the hydraulic pump 23 to the steering hydraulic valve device A, and an oil path from the steering hydraulic valve device A to the hydraulic device C for lifting and lowering the work equipment. A hydraulic steering device characterized by being interposed between.