JPH0530669B2 - - 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. A valve 16 is attached, and a drive arm 23 is provided to act on the push/pull spool 17 of the control valve 16 in accordance with the amount of steering from the Pitman arm 20.

[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.

The purpose of the present invention is to prevent the operation force from acting on the control valve even during artificial forced steering operation, to avoid unnecessarily increasing the size of the control valve, and to smoothly operate the mechanism adopted for this purpose. The point is to provide what we can.

[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 pivoted to be able to swing relative to the cylinder case; ○The rocking movement is driven by the robot arm. ○C) This operation pin is interlocked and connected to the push/pull spool of the control valve; ○D) The operation pin is inserted into the long hole provided in the mounting base. and (e) The operating pin is configured to act on one end of the elongated hole before reaching the stroke end of the push/pull spool, and its effects are as follows.

[Operation] According to characteristic configuration ○C, while the power steering device is operating normally, the operating pin drives the push/pull spool to operate the control valve, and according to characteristic configuration ○I○ho During forced steering, the actuating pin first acts on one end of the elongated hole, and the steering force is transmitted from the actuating pin to the hydraulic cylinder case via the mounting base without being transmitted to the control valve.

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

Moreover, according to characteristic configuration ○A, the mounting base is pivoted to be able to swing relative to the cylinder case, so the steering operation angle can be switched from point 1 to point 2 as shown in Fig. 5. As shown in FIG. 4, when the steering cylinder 14 and the control valve 16 Even if the steering cylinder is driven via In addition, since the elongated hole is drilled along the operating direction of the push/pull spool, even if the drive arm is of a swing type, the contact position with the elongated hole of the actuating pin for transmitting the operating force is fixed. can be limited to one end of the elongated hole by the swinging of the mounting base, and there is no possibility that it will come into contact with the middle side of the elongated hole and cause strain.

〔Effect of the invention〕

In terms of operation, 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 also reduces the structure in which operating force is applied to the mounting base during manual steering operation. Therefore, the material of this mounting base can be selected arbitrarily to select one with strength suitable for the operating force, and it is also easy to replace when it wears out. Furthermore, the reaction force exerted on the actuation pin, which pushes the mounting base due to its action, is reduced because there is no "kink" between it and the mounting base, and there is no need to provide an unnecessarily large actuation pin itself. .

〔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.

The structure of the steering handle 6 will be explained in detail. As shown in FIG. 6, a vertical rotating shaft 27 is pivotally supported on a handle post 26 to be connected to a Pitman arm 20 (described later) via a speed reduction mechanism (not shown), and a steering wheel 28 is attached to the tip of this rotating shaft 27. is fixed with a nut 29 to prevent it from being pulled out upwards, and a disc spring 30 is interposed between the steering wheel 28 and the upper surface of the handle post 26, so that the friction force of the disc spring causes the steering wheel to tighten. 6 can be prevented from fluttering, and the straightness can be improved.

Next, a 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 to 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. A rotation shaft 22 is pivotally supported on a holder 31 in a vertical position, and a drive arm 23 is spline-fitted to the upper end of the rotation shaft 22 so as to be able to rotate integrally therewith, and a transmission arm 24 interlockingly connected to the connection pipe 21 is fitted to the lower end of the rotation shaft 22. It is worn and configured. An operating pin 25 is erected at the tip of the drive arm 23, and as shown in FIGS. 2 and 3, the operating pin 25 is attached to 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 long hole 18a formed in is configured to transmit the amount of operation to the push/pull spool 17. Here, the long hole 18
The length of a is 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 operating pin is opened without transmitting driving force to the control valve 16 case. 25 drives the steering cylinder 13, so that the steering can be manually operated. Since the base end large diameter portion 25b of the actuation pin 25 comes into contact with one end 18b of the elongated hole 18a, the mounting board 18 can withstand a large actuation reaction force applied to the actuation pin 25 during manual steering operation. Demonstrates sufficient 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 operated. will be 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 is not limited to a flat plate.

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 vertical side view showing the mounting state of the operating pin and control valve, Fig. 3 is a plan view showing the positional relationship between the operating pin and the elongated hole on the mounting base side, Fig. 4 is an overall plan view, and Fig. 5 is a line diagram showing the operating state of each member in Fig. 4, Fig. 6 is a longitudinal side view showing the operation resistance mechanism for the steering handle, Fig. 7 is a side view showing the riding rice transplanter, and Fig. 8 is a conventional example. FIG. 13... Steering cylinder, 14... Cylinder case, 16... Valve, 17... Push/pull spool, 18... Mounting base, 18a... Long hole, 1
8b...One end, 20...Pittman arm, 23
... Drive arm, 25 ... Actuation pin.

Claims (1)

[Claims] 1. An operating pin 25 is erected on a swinging drive arm 23 driven by a pitman arm 20, and a valve 16 for controlling a steering cylinder 13 acting on a knuckle arm 11 is fixed to a mounting base, and a push-pull spool is attached. The operating pin 25 is inserted into the elongated hole 18a formed in the mounting base 18 along the operating direction of the spool 17, and the insertion tip of the operating pin 25 is interlocked and connected to the push/pull spool 17. The mounting base 18 is pivotally supported to the cylinder case 14 so as to be able to swing relative to the cylinder case 14, and the operating pin 25 is configured to come into contact with one end 18b of the elongated hole 18a before reaching the stroke end of the push/pull spool 17. A power steering device for a certain agricultural machine.