JPH0530668B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improvements in power steering devices for agricultural machines such as rice transplanters.

[Conventional technology]

In this type of power steering device, conventionally, as shown in FIG. At the same time, the control valve 16 is installed on the hydraulic cylinder 13, and the pitman arm 20 is attached to the push/pull spool 17 of the control valve 16.
A drive arm 23 is provided that acts on the push/pull spool 17 according to the amount of steering from the drive arm 23.

[Problem that the invention seeks to solve]

In the above configuration, in an unexpected situation where the supply of pressure oil to the power steering hydraulic cylinder is stopped, the push/pull spool must be positioned at the stroke end and the hydraulic cylinder must be forced to operate manually. Therefore, the steering operation force acts directly on the control valve, and the control valve has to have strength not only against hydraulic pressure but also against the operation force, resulting in a strong and large valve structure.

SUMMARY OF THE INVENTION An object of the present invention is to provide a control valve which can be prevented from becoming unnecessarily large in size by preventing any operating force from acting on the control valve even during a forced steering operation.

[Means for solving problems]

The characteristics of the present invention are as follows: ○B The control valve is mounted on a mounting base, and this mounting base is mounted on the cylinder case; ○The operating pin is erected on the drive arm driven by the robot arm. , ○C The point where this operating pin is interlocked and connected to the push/pull spool of the control valve, ○D The point where the operating pin is inserted into the long hole provided in the mounting base, and ○E The point at the stroke end of the push/pull spool. The operating pin is configured to act on one end of the elongated hole, and its effects are as follows.

[Effect]

According to feature configuration ○c, while the power steering device is operating normally, the operating pin drives the push/pull spool and operates the control valve.
Due to the characteristic configuration ○I○Ho, during artificially forced steering, the actuation pin acts first on one end of the elongated hole, and the steering operation force is not transmitted to the control valve, but is transferred from the actuation pin to the hydraulic cylinder via the mounting base. conveyed to the case.

Therefore, no operating force is applied to the control valve during a forced steering operation.

〔Effect of the invention〕

As a result, the control valve only needs to have a structure strong enough to withstand the control hydraulic pressure, so it can be made more compact than conventional valves, and it occupies less space, making it easier for the undercarriage area where equipment is congested. There are few restrictions on placement.

〔Example〕

As shown in FIG. 7, the traveling body 3 is supported by a pair of left and right steering front wheels 1, 1 and rear wheels 2, 2.
An engine 5 is attached to the front part of the machine via a mounting frame 4, a driving part 7 equipped with a steering handle 6 is arranged in the middle part of the machine body, and a lifting link 9 driven by a lifting hydraulic cylinder 8 is installed in the rear part of the machine body. A riding rice transplanter, which is an example of an agricultural machine, is equipped with the seedling planting device 10.

Next, the power steering device for the steering front wheels 1, 1 will be described in detail. As shown in FIG. 1, each knuckle arm 1 of the steering wheels 1,
1 and 11 are connected to each other via a tie rod 12, and the one knuckle arm 1
The arm 11a extended so as to be able to operate integrally with the engine 1 is interlocked with the cylinder case 14 of the power steering hydraulic cylinder 13, and the piston rod 13A of the power steering hydraulic cylinder 13 is extended from the engine mounting frame 4. It is fixed to the mounting bracket 15.

Control valve 16 for the hydraulic cylinder 13
is fixed to a flat mounting base 18 so that the operating direction of the push/pull spool 17 is substantially along the expansion and contraction direction of the hydraulic cylinder 13, and one end of this mounting base 18 is attached to the hydraulic cylinder 13. The hydraulic cylinder 13 is fitted onto the hydraulic piping mounting boss 19 and pivoted horizontally around the axis X of the boss 19.
installed on. In FIG. 4, X' and X'' indicate the movement positions of the axis X, respectively.The mounting position of the base 18 to the boss 19 is set at the large diameter portion on the proximal side of the oil supply/drainage port 19a. .

On the other hand, the drive system for this control valve 16 is
4, a connecting pipe 21 is attached to the swinging end of the pitman arm 20 operated by the steering handle 6, and a connecting pipe 21 is attached to the side of the engine mounting frame 4 near the control valve 16. Rotation axis 2 on vertical holder
2, a drive arm 23 is rotatably attached to the upper end of the rotation shaft 22, and a connecting pipe 2 is attached to the lower end of the rotation shaft 22.
A transmission arm 24 interlockingly connected to the transmission arm 1 is spline-fitted. The drive arm 2
An operating pin 25 is erected at the tip of 3, and as shown in FIGS. 2 and 3, this operating pin 25 is formed on the mounting base 18 along the operating direction of the push/pull spool 17. The end portion 25a, which has a smaller diameter than the insertion portion into the elongated hole 18a, is inserted through the elongated hole 18a and fixed from a direction perpendicular to the push/pull spool 17, thereby controlling the amount of operation by the Pitman arm 20. is configured to transmit this to the push/pull spool 17. Here, the length of the elongated hole 18 is formed to be shorter than the stroke of the push/pull spool 17, and when the supply of pressure oil to the hydraulic cylinder 13 is stopped, the driving force is transmitted to the case of the control valve 16. The steering cylinder 13 is driven by the operating pin 25 in such a state that the steering can be operated manually. Since the base end large diameter portion 25b of the actuation pin 25 comes into contact with one end of the elongated hole 18a, the mounting board 18 is sufficiently secured against the large actuation reaction force applied to the actuation pin 25 during manual steering operation. Demonstrates great strength.

Next, the movements of each linkage mechanism during power steering operation will be explained. As shown by the solid line in Figure 5,
When the steering wheel 6 is turned all the way to the right and returned to the left, the pitman arm 20 shifts from the state of point 1 to the state of point 2, and the connecting pipe 21, transmission arm 24, and drive arm 23 operate accordingly. Pin 25 pushes push/pull spool 17.
In this state, when the cylinder case 14 of the hydraulic cylinder 13 is extended and the knuckle arm 11 is rotated to the state of point 2, the steering front wheel 1 is rotated, and the control valve 16 connected to the cylinder case 14 is rotated. Since the mounting base 18 is moved in the direction in which the cylinder case 14 is operated, the relative positional relationship between the drive arm 23 and the control valve 16 is returned to the original state, the control valve 16 is shifted to the neutral state, and the hydraulic cylinder 13 is moved. Operation is stopped. Further from this state,
When the steering wheel 6 is turned to the left, the pittman arm 20 and the knuckle arm 11 move to point 3.
It operates towards.

To explain the hydraulic system to the control valve 16,
Pressure oil from the pump P is injected into the control valve 16 and flows from the control valve 16 into the power steering hydraulic cylinder 13.
The return oil from 3 is supplied to the lifting hydraulic cylinder 8.

[Another example]

The mounting base 18 does not have to be plate-shaped.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of the power steering device for agricultural machinery according to the present invention, and FIG. 1 is an overall side view;
Fig. 2 is a longitudinal side view showing the mounting state of the actuation pin and control valve, Fig. 3 is a plan view showing the positional relationship between the actuation pin and the long hole on the mounting board side, Fig. 4 is an overall plan view, and Fig. 5 is FIG. 4 is a diagram showing the operating state of each member, FIG. 6 is a side view of a conventional example, and FIG. 7 is a side view of a riding rice transplanter. 13... Steering cylinder, 14... Cylinder case, 16... Control valve, 17... Push/pull spool, 18... Mounting base, 18a... Long hole, 18b... One end, 20... Pitman arm, 23 ... Drive arm, 25 ... Actuation pin.

Claims (1)

[Claims] 1 Attach the mounting base 18 to which the control valve 16 for the steering cylinder 13 that acts on the knuckle arm 11 is fixed to the cylinder case 14 of the cylinder 13, and attach the operating pin 25 to the drive arm 23 driven by the Pitman arm 20. The actuating pin 25 is interlocked and connected to the push/pull spool 17 of the control valve 16, and is inserted into and engaged with the elongated hole 18a formed in the mounting base 18 to reach the stroke end of the push/pull spool 17. A power steering device for an agricultural machine in which the operating pin 25 is previously configured to come into contact with one end 18b of the elongated hole 18a.