JPS59209967A - Power steering device of agricultural tractor - Google Patents

Abstract

PURPOSE:To reduce the size of a hydraulic cylinder, by method wherein the rod end of a hydraulic cylinder, which performs steering through movement of a bell crank, is pivotally secured to a fixture part, and the one end of the bell crank is pivotally secured to a cylinder body. CONSTITUTION:Right and left tie-rods are coupled to the one end, having two holes formed in the shape of an eyeglass, of a bell crank 6 which is pivotally secured to a front axle bracket 1 of an agricultural tractor by means of a pivotally-securing pin 10, and a hydrualic cylinder A is linked to the other end. In which case, the hydraulic cylinder A is formed such that a piston 3, having piston rods 3a and 3c with the same diameter protruding from both sides of a piston part 3b, mates inwardly of a cylinder 4 provided at both ends of a central case 4b with a cover 4c and a pivotally-securing part 4a. The end of the piston rod 3a is pivotally secured to the bracket 1, and the pivotally-securing part 4a of the cylinder 4 is coupled to the other end of the bell crank 6 through the medium of a pivotally-securing body 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power steering device for an agricultural tractor.

There are two types of power steering systems for mobile vehicles.

One type incorporates a hydraulic control valve and a hydraulic cylinder into a conventional steering gear box, and uses the hydraulic cylinder to move a pitman arm to push and pull a drag rod, and is used for small-sized vehicles.

The other type has only a hydraulic control valve in the steering gear box, with a separate hydraulic cylinder installed near the front wheels, which rotates the tie rods and knuckle arms.

The present invention relates to the latter method.

There was a big problem when a separate hydraulic cylinder was provided to rotate the bell crank and the bell crank was used to push and pull the left and right tie rods. In a normal hydraulic cylinder, the piston rod only protrudes in one direction, so the piston's working area and oil volume are different between the oil chamber on the side where the piston rod is protruding and the oil chamber on the side where it is not protruding.
The steering speed differs when turning to the right and turning to the left.

In order to solve this problem, if the piston rod protrudes from the piston on both sides, the piston rod will become abnormally long, and if the hydraulic cylinder side is fixed and the piston rod side is fixed on the bell crank, the piston rod will protrude on both sides. Therefore, it is necessary to provide extra room for movement.

In order to overcome this difficulty, the present invention conversely moves the hydraulic cylinder side, fixes the piston rod, and eliminates the need to create extra space since there is no movement range for the hiss ly rod. .

Also, if you try to fix the hydraulic cylinder side to the bell crank like this, since the piston rod passes through the center, you will not be able to insert the pins that pass through the bell crank and the hydraulic cylinder up and down, but, Since it is not possible to support it with a cantilever pin in either the upper or lower direction, the present invention projects a pivot protrusion vertically from the side of the hydraulic cylinder, and applies a bell crank to this protrusion from below to support the pivot protrusion. The bell crank pivot is loosely fitted, the bell crank pivot is inserted as a separate member from above, and finally the bell crank pivot is fixed to the bell crank by tightening bolts.The purpose of the present invention is as described above. The present invention will be described in detail based on the configuration of the embodiment shown in the accompanying drawings.

FIG. 1 is a plan view of the front axle bracket (1).

FIG. 2 is a partial front sectional view of the front axle bracket (1) and the front axle portion. FIG. 3 is a side sectional view of FIG. 2. FIG. 4 is a plan view of the hydraulic cylinder device (A). FIG. 5 is a side sectional view. FIG. 6 is a rear view.

The front axle bracket is located at the bottom of the hood of the agricultural tractor, and is fixed to the cylinder case at the bottom of the engine and protrudes forward.
L) (7R) assembly with center pin device (
8), it is pivoted so that it can move left and right, up and down. or,
Its tip is also used for bumpers, front weight brackets, etc.

For agricultural tractors, front axle brackets, engines, clutch housings, transmission cases,
The rear axle case constitutes the fuselage support member.

In the present invention, this front axle bracket (
A bell crank (6) is pivotally supported at a position shifted to the left by (a) from the center of the fuselage in 1) using a pivot pin oO).

The center of the center pin (8) coincides with the center of the aircraft, and the large diameter part of the front axle that makes up the front differential case moves up and down left and right near the center of the aircraft, so there is a risk that the bell crank may engage with it. , and the bellcrank is slightly eccentric by a distance (a).

The bell crank's pivot pin passes through the upper wall of the front axle bracket (1) at its upper part, and from the lower part at the fixing plate (
9) and bolt the fixing plate (9) from the underside of the front axle bracket (1).

Two eyeglass-shaped holes are provided at the rear end of the bell crank (6), into which the left and right tie rods are fixed, and the tie rod is pivotally connected to the knuckle arm of the front wheel kingpin.

A hydraulic cylinder device (A) is pivotally connected to the other end of the bell crank (6).

The structure of the hydraulic cylinder device (A) is shown in FIGS. 4, 5, and 6. The hydraulic cylinder device (A) consists of a hydraulic cylinder (4) and a piston (3).
-ru.

The hydraulic cylinder (4) consists of a case (4b) in the center, a lid (4C) at the front end, and a pivot part (4a) at the rear end, and the case (4b) and the pivot part (4a) are fixed by welding. ,
The case (4b) and the lid (4C) are assembled using screws. Hydraulic cylinder configured like this (4)
Inside the piston part (3b) and piston rod (3a) (3
A piston (3) made of C) is fitted.

Since the piston rods (3a) (3c) of the same diameter protrude from the central piston part (3b) to both sides, the amount of oil in the oil chambers on both sides is the same, and there is no difference in steering speed between the left and right sides.

Pressure oil is sent to the oil chamber made up of this hydraulic cylinder (4) and piston (3) through pipes (2a) and (20).

(2C) is an adapter, and (2) is a ruki/pull pipe.

In Figure 1, flexible pipes (2) and (2')
shows the state in which the flexible pipe has moved for steering purposes.

Attach part (3a) of the piston rod to the front left corner of the front axle bracket (1) with the pivot pin (
It is supported loosely with green onions. Of the piston rod (3C
) is not separately supported and is released because this part rotates left and right as the hydraulic cylinder moves back and forth.

As shown in Fig. 5, the pivot portion (4) of the hydraulic cylinder (4)
In a), two pivot protrusions are formed on the upper and lower sides.

With a normal structure, it would be sufficient to insert one pin through the bell crank and hydraulic cylinder, but in the present invention, the piston rod (3C) runs inside, so the pin cannot penetrate. Separate pivot protrusions were protruded at the top and bottom. The lower side of this pivot protrusion is loosely fitted into the hole of the bell crank (6), the bell crank pivot body (5) is loosely fitted into the upper pivot protrusion, and the bell crank pivot body (5) is bolted. (14) is fixed to the bell crank (6).

In addition, as shown in Fig. 1, a hydraulic cylinder device (A
) comes from the engine side, bends forward in a U-shape, and then gradually approaches the hydraulic cylinder device from the front and is fixed. By doing this, when the rear end of the hydraulic cylinder device rotates, the flexible pipe can absorb this rotation with the U-shaped deflection at the front, improving the durability of the flexible pipe against continuous deflection. This is because it is possible.

As described above, the present invention has a configuration in which a bell crank is pivotally supported on a front axle bracket, and the bell crank is rotated by a hydraulic cylinder device to perform steering. One end of the piston rod is pivoted to the front axle bracket, and two parts of the hydraulic cylinder are pivoted to the end of the bell crank, so the piston rod can be installed on both sides of the piston, so the amount of oil in the oil chambers on both sides can be reduced. are the same, and the left and right steering speeds are the same.

Also, when the hydraulic cylinder side is pivoted, the long piston rod side moves back and forth, so it is necessary to provide a space within the front axle bracket (1) that allows this movement and rotation. By fixing the hydraulic cylinder, the hydraulic cylinder will only move within this length range, so there is no need to provide extra space at the front and rear.
All you need to do is provide a space in the front axle bracket for left and right rotation of the rear end piston rod. This allows the hydraulic cylinder device to be made more compact and the front axle bracket to be more compact.

In addition, a protrusion was protruded from the outer periphery of the hydraulic cylinder, and the protrusion was fitted into the bell crank and the bell crank pivot to pivotally connect the hydraulic cylinder and the bell crank. The part that cannot be penetrated by a pivot pin can now be pivoted on both sides without having to be cantilevered, making it stronger and easier to assemble since it can be done from above.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the front axle bracket (1). Figure 2 is the same (partial front sectional view of the front axle bracket (1) and front axle part. Figure 3 is a side sectional view of Figure 2. Figure 4 is a plan view of the hydraulic cylinder device (A). Figure 5 is a side sectional view. Figure 6 is a rear view. (A) Hydraulic cylinder device (1) Front axle bracket (3)
Piston (4)...Hydraulic cylinder (5)
... Bell crank pivot (6) ... Bell crank applicant Yanmar Diesel Co., Ltd. agent Patent attorney Toshikazu Yano

Claims (2)

[Claims] (1) In a configuration in which a bell crank is pivotally supported on a front axle bracket, and the bell crank is rotated by a hydraulic cylinder device to perform steering, a piston rod is protruded from both sides of the piston of the hydraulic cylinder device, and the piston rod is rotated by a hydraulic cylinder device. A power steering device for an agricultural tractor, characterized in that one end is pivoted to a front axle bracket, and a part of a hydraulic cylinder is pivoted to an end of a bell crank. (2) A protrusion protrudes from the outer periphery of the hydraulic cylinder, and the protrusion is fitted into the bell crank and the bell crank pivot, thereby pivotally connecting the hydraulic cylinder and the bell crank. The power steering device for the agricultural tractor described.