JPS6371479A - Power steering device for agricultural machine - Google Patents

Abstract

PURPOSE:To obtain the small-sized control valve which is made compact by suppressing the transmission of the steering operation force to a steering control valve when the compulsory steering operation is performed when a power steering device for agricultural machine is in trouble. CONSTITUTION:A hydraulic cylinder 13 driven by the oil pressure which is supply/discharge-controlled by a control valve 16 is installed, and a steering front wheel 1 is steered by turning a knuckle arm 11 by the drive of the hydraulic cylinder 13. In this device, an operating pin 25 is erected onto a driving arm 23 driven by a pitman arm 20 interlocked with the operation of a steering wheel 6. Further, the control valve 16 is fixed onto an installation base 18, and the operating pin 25 is inserted into an elliptical hole 18a drilled onto the installation base 18 along the operation direction of the control valve 16, and the top edge of the operating pin 25 is interlocking-connected with the pushing/ pulling spool 17 of the control valve 16. Therefore, the operating pin 25 is allowed to contact one edge of the elliptical hole 18a before the pushing/pulling spool 17 reaches the stroke end.

Description

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

[Conventional technology]

In this type of power steering device, conventionally, as shown in FIG. 8, a power steering hydraulic cylinder (13) is installed between one knuckle arm (11) and the fuselage frame (4). A control valve (16) is attached to the hydraulic cylinder (13), and a spool (16) is attached to the push/pull spool (17) of the control valve (16) according to the amount of steering from the pitman arm (2o).
17) was provided.

[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 to forcefully operate the hydraulic cylinder. Therefore, the steering operation force acts directly on the control valve,
The structure of the valve has become robust and large because it requires strength not only against hydraulic pressure but also against the aforementioned operating force.

An object of the present invention is to prevent the operation force from acting on the control valve even during a forced steering operation, thereby avoiding an unnecessary increase in the size of the control valve, and simplifying the structure by making the control valve dual-purpose. The point is to provide the following.

[Means for solving problems]

The characteristics of the present invention are as follows: (1) The control valve is mounted on a mounting base, and this mounting base is pivotally supported so as to be able to swing relative to a hydraulic piping connection boss provided on the cylinder case, and an O-pitman arm. The operating pin is installed upright on the swinging drive arm driven by the control valve, and the operating pin is interlocked and connected to the push/pull spool of the control valve. The operating pin is inserted through it, and 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 the effects are as follows.

[For production]

■ Due to feature configuration O, while the power steering device is operating normally, the actuation pin drives the push/pull spool to operate the control valve, and due to feature configuration ■, during artificially forced steering, the actuation pin goes first. The steering operation force is transmitted from the operating 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, due to the characteristic structure ■, the mounting base is pivoted to be able to swing relative to the cylinder case, so the steering operation angle changes from point (1) to point (2) as shown in Fig. 6. As shown in FIG. 5, the steering cylinder (14) and control valve (16)
) The mounting base is flexible to achieve a situation in which the relative position with respect to the steering wheel must change, and no "kinking" occurs even when the steering cylinder is driven by the operating pin via the mounting base. 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 will not hit the middle side of the elongated hole and cause twisting.

(2) Furthermore, since the mounting base is pivoted to the piping connection boss provided on the cylinder case as a fulcrum, there is no need to provide another fulcrum.

〔Effect of the invention〕

Function ■The control valve only needs to be strong enough to withstand the control hydraulic pressure, so it can be made more compact than conventional valves, and it also has a structure in which the operating force is applied to the mounting base during manual steering operation. Since we take
The material of this mounting base can be arbitrarily selected to have a strength suitable for the operating force, and it can be easily replaced when worn out. Furthermore, the reaction force exerted on the actuating pin that pushes the mounting base due to action (■) is also reduced because there is no "kinking" between it and the mounting base, and there is no need to provide an unnecessarily large actuating pin itself. do not have.

In addition, according to operation (2), the equipment configuration can be simplified by making the piping connection boss also serve as a pivot point.

〔Example〕

As shown in Figure 7, a pair of left and right front steering wheels (1)
The engine (5) is attached to the front part of the traveling body (3) supported by the rear wheels (2) and (2) via the mounting frame (4), and a steering handle is installed in the middle of the body. (6), and a lifting link (9) and a seedling planting device (10) driven by a lifting hydraulic cylinder (8) at the rear of the machine. The machine has been configured.

The structure of the steering handle (6) will be explained in detail.

As shown in FIG. 9, a vertical rotation shaft (27) is pivotally supported on a handle post (26) so as to be linked to a pitman arm (20), which will be described later, via a speed reduction mechanism (not shown). (27) At the tip of the steering wheel (
28), and an elastic resistor (30
), it is possible to prevent the handle (6) from wobbling due to the frictional force generated by this resistor, thereby improving straightness.

Next, the power steering device for steering front vehicle width (1), (1) will be described in detail. As shown in FIG.
), and an arm (lla
) and the cylinder case (14) of the power steering hydraulic cylinder (13) are interlocked, 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)
The operating direction of the push/pull spool (17) is determined by the hydraulic cylinder (
13) is fixed to a flat mounting base (18) so as to take a posture substantially along the expansion and contraction direction of the mounting base (13), and this mounting base (18)
8) Fit one end of the hydraulic cylinder (13) onto the hydraulic piping mounting boss (]9), and pivot it horizontally around the axis (X) of the boss 09), so that the hydraulic cylinder (13) is attached. In Fig. 5, (X') and (X'') respectively indicate the movement position of the axis (X).
) has a control valve (1
A connecting fitting (29) provided with an oil supply/discharge port (29a) connected to the hydraulic cylinder (13) is screw-fitted to constitute a supply/discharge communication port for the hydraulic cylinder (13).

On the other hand, as shown in FIGS. 2 and 5, the drive system for this control valve (16) is connected to a pipe (21) connected to the swinging end of a pitman arm (20) operated by a steering handle (6). At the same time as installing the control valve (
16) A rotating wheel (22) is attached to a vertical holder (31) fixed to the side of the engine mounting frame (4) nearby.
The driving arm (23) is pivotally supported at the upper end of the rotating wheel (22) and the connecting pipe (21) is integrally rotatable at the upper end of the rotating wheel (22).
A transmission arm (24) is spline-fitted to be operatively connected to the transmission arm (24). Therefore, the control valve (16)
is located above the engine mounting frame (4) and is less susceptible to the effects of muddy water, etc. An operating pin (25) is erected at the tip of the drive arm (23), and this operating pin (25)
5) is inserted into a long hole (18a) formed in the mounting base (18) along the operating direction of the spool (17), as shown in FIGS. The tip (25a), which has a smaller diameter than the insertion part into the elongated hole (18a), is fixed through the push/pull spool (17) from a direction perpendicular to the push/pull spool (17), thereby controlling the amount of operation by the pitman arm (20). The spool (17) is configured to transmit.

Here, the length of the elongated hole (18a) is the same as that of the push/pull spool (1
7), and when the supply of pressure oil to the hydraulic cylinder (13) is stopped, the operating pin (25) will not transmit driving force to the control valve (16) case. to drive the steering cylinder (13),
It is configured so that the steering can be operated artificially. Since the large diameter portion (25b) at the base end of the actuation pin (25) comes into contact with one end (18b) of the long hole (18a), a large actuation reaction is applied to the actuation pin (25) during manual steering operation. The mounting board (18) exhibits sufficient strength against force.

Next, the movements of each linkage mechanism during power steering operation will be explained. As shown by the solid line in Figure 6, when the steering wheel (6) is turned all the way to the right and returned to the left, the pitman arm (20) changes from point (1) to point (2).
Accordingly, the connecting pipe (21), the transmission arm (24), and the drive arm (23) operate, and the operating pin (25) pushes the spool (17). In this state,
When the cylinder case (14) of the hydraulic cylinder (13) extends and the knuckle arm (11) rotates to the state of point (2), the front steering wheel (1) is rotated and the cylinder case ( control valve (14) connected to the control valve (14);
6) is moved in the direction of operation of the cylinder case (14), so the relative positional relationship between the drive arm (23) and the control valve (16) returns to its original position, and the control valve (16) The hydraulic cylinder (13
) is stopped. When the steering wheel (6) is further turned to the left from this state, the pitman arm (20) and the knuckle arm (11) operate toward point (3). The rotation angles (θ1) and (θ2) of the focus man arm (20) from the neutral position to the left and right are approximately the same.
It is set at an angle that allows the steering feel to be similar to that of manual steering operation.

To explain the hydraulic system for the control valve (16), pressure oil from the pump (P) is supplied to the control valve (16), and from this control valve (16) flows into the power steering hydraulic cylinder (13). , this hydraulic cylinder (13)
The return oil is supplied to the lifting hydraulic cylinder (8).

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 an agricultural working machine according to the present invention, in which FIG. 1 is a longitudinal cross-sectional view showing a state in which it is attached to a mounting base and a power steering cylinder, FIG. 2 is an overall side view, and FIG. The figure is a vertical side view showing the mounting state of the operating pin and the control valve, FIG. 4 is a plan view showing the positional relationship between the operating pin and the long hole on the mounting base side, FIG. 5 is an overall plan view, and FIG.
The figure is a diagram showing the link connection mechanism corresponding to Figure 5, and Figure 7.
The figure is a side view showing a riding-type rice transplanter, FIG. 8 is a side view showing a conventional example, and FIG. 9 is a longitudinal side view showing a steering handle structure.

Claims (1)

[Claims] An operating pin (25) is installed upright on a drive arm (23) driven by a knuckle arm (20), and a valve (16) that controls a steering cylinder (13) that acts on the knuckle arm (11) is mounted on a mounting base. The operating pin (25) is inserted into a long hole (18a) that is fixed to the base and is bored in the mounting base (18) along the operating direction of the push/pull spool (17). The insertion tip of 25) is interlocked and connected to the push/pull spool (17), and
The mounting base (18) is pivotally supported on a piping connection boss (19) provided on the cylinder case (14), and the operation is performed before the push/pull spool (17) reaches the stroke end. A power steering device for an agricultural working machine, in which a pin (25) is configured to come into contact with one end (18b) of a long hole (18a).