JPH07257411A - Front wheel drive device for tractor - Google Patents

Abstract

PURPOSE:To improve steering performance by improving arrangement structure of a front diff device and a steering cylinder of a four-wheel drive tractor and reducing a crossed axes angle formed by a tie-rod and a piston rod. CONSTITUTION:A front diff device and a part of a steering cylinder for power steering are stored in a front accel case of a four wheel drive motor tructor and a recessed portion 10e is formed in an outer periphery of a cylinder tube of the steering cylinder in this front accel case. A ring gear 15 of the front diff device is confronted and arranged in the recessed portion 10e.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for arranging a power steering cylinder and a front wheel drive device in a front axle case.

[0002]

2. Description of the Related Art Conventionally, in a front axle of a four-wheel drive type tractor, a power steering cylinder in which a dual rod type power steering cylinder is integrally supported in a front axle case and a steering wheel is rotatable. Is publicly known. For example, it is a technique described in Japanese Utility Model Publication No. 3-12612.

[0003]

However, in the above-mentioned conventional structure, since the wall for isolating the power transmission gear and the cylinder is provided, the center of the axle is separated from the center of the cylinder. When steering, the angle of intersection between the tie rod and the piston rod becomes large, and the bending component force of the piston rod becomes large.In particular, when the cylinder rod is extended to the maximum, the cantilever length becomes the maximum and the bending load is large. Uneven wear occurs on the sliding surface between the rod support bush and piston and the inner circumference of the cylinder, which makes sliding impossible, and when the knuckle arm is lengthened to reduce the crossing angle, the cylinder stroke Also needs to be long, which results in a large steering drive device and an increase in cost. Similarly, when the steering cylinder is arranged above the axle case in order to reduce the crossing angle, it interferes with the front frame, and the lower part of the frame has to be cut out, resulting in a decrease in frame strength and damage.

[0004]

The present invention uses the following means in order to solve the above problems. That is, a front diff device and a part of a steering cylinder for power steering are housed in a front axle case of a four-wheel drive tractor, and a concave portion is formed on the outer circumference of a cylinder tube of the steering cylinder in the front axle case. It is arranged with the ring gear of the differential device facing.

[0005]

By using such means, the ring gear enters the recess formed on the outer periphery of the cylinder tube, and the distance between the center of the steering cylinder and the center of the front axle case is shortened. The crossing angle between the piston rod and the tie rod during turning can be reduced, the load on the piston rod from the tie rod is reduced, and the turning operation can be performed smoothly.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the structure of one embodiment of the present invention will be described in the case of a tractor as a traveling vehicle shown in the accompanying drawings. Fig. 1 is a front view of front wheels and front axle case, Fig. 2
Is a front sectional view of a front axle case, FIG. 3 is a side sectional view of the same, FIG. 4 is a partial sectional view of a steering cylinder, and FIG. 5 is a plan view showing a connected state of a steering cylinder, a tie rod, and a knuckle arm.

In FIG. 1, a front axle case 1
Is divided into three parts, and is composed of a center case 1M in the center, a left axle case 1L and a right axle case 1R protruding to both sides of the center case 1M, which are fixed on both sides of the center case 1M by bolts 6 ... The axle case 1 is supported so as to be capable of swinging left and right with respect to an axle frame 2 that constitutes a body frame, and as shown in FIG. 3, a pivot pin 1a is provided at the center front end of the center case 1M.
And the input shaft case 5 attached to the center of the rear part of the center case 1M is freely rotatably supported by the bracket 4 that is hung from the axle frame 2 and is rotatably supported by the bracket 3 that is hung from the axle frame 2. Supported by.

A steering cylinder 10 for power steering, which will be described later, is provided at the front of the center case 1M.
Are horizontally installed in the horizontal direction, and the steering cylinder 10 is a double-rod type double-acting cylinder in which piston rods 10a, 10a are projected to both sides, and a spherical joint 11, 11 is formed at the tip of the piston rods 10a, 10a.
Is connected to the tie rods 12 and 12, and the other end of the tie rods 12 and 12 is connected to the knuckle arms 13 and 13. The knuckle arm 13/13 has front wheels 9/9
Is connected to the rotating case 20 that pivotally supports the rotating case 20.
The king pin that supports the front wheel 9 is rotatable about the front wheel 9 by the left and right sliding of the piston rods 10a.
・ 9 is turned to the left and right so that it can be steered.

The center case 1M also serves as a front differential case. As shown in FIGS. 2 and 3, the front wheel drive shaft projecting forward from a rear transmission case (not shown) is connected to the input shaft case 5 via a universal joint. Power is transmitted to an input shaft 14 that is rotatably supported by a pinion gear 14a formed at the front end of the input shaft 14, and the pinion gear 14a is mounted on the left and right axle cases 1.
Two sets of bevel gears 17 are engaged in the differential gear case 16 with a ring gear 15 fixed on a differential gear case 16 that is rotatably supported by L and 1R via bearings.
.17, 18 and 18 are rotatably meshed and housed to form a front diff device, and the left and right front transmission shafts 19 and 19 are laterally suspended in the left axle case 1L and the right axle case 1R. The bevel gears 18 and 18 are fixed to one end, and the other end is inserted into the rotating case 20 and 20 so that the front wheels 9 and 9 can be driven via gears or the like.

As shown in FIG. 2, FIG. 3, and FIG. 4, the steering cylinder 10 is horizontally installed in the front portion of the front axle case 1 so as to partially enclose the steering cylinder 10, and the steering cylinder 10 is constructed symmetrically. An annular convex portion 10c is formed at the center of the outer periphery of the cylinder tube 10b, and a locking hole 10d is formed (but not penetrated) at the center of the outer periphery of the annular convex portion 10c. On the other hand, an insertion hole is opened in the center upper surface of the center case 1M so as to be aligned with the position of the locking hole 10d, and the locking tool 21 externally fits the sealing material 22 to the center direction (radial direction) from the outside of the center case 1M. )
The cylinder tube 10b is fixed by being inserted into the locking hole 10d. In this embodiment, the locking tool 21 is made up of only one bolt, but more locking tools may be provided.

Then, recesses 10e, 10e are formed on the outer circumferences on both sides of the annular projection 10c, and the recesses 10e, 10e are formed.
The opposite side surfaces 10f, 10f on the outer side of the cylinder are brought into contact with the outer surface of the center case 1M during assembly to perform axial positioning, and sealing material insertion grooves are provided on the outer circumference of the cylinder tube 10b on both sides thereof. 10 g and 10 g are formed and the sealing members 23 and 23 are fitted, and the cylinder tubes 10 b on both sides are inserted and supported in the left axle case 1 L and the right axle case 1 R to fix the cylinder tube 10 b in the direction perpendicular to the axis. Then, the pressure oil ports 10h and 10h are opened at both ends of the cylinder tube 10b and connected to the steering control valve through a pipe (not shown). When the steering handle of the machine is turned during traveling, the steering control valve Is switched to supply pressure oil to one pressure oil port 10h, and the piston 10
The piston rods 10a and 10a are expanded and contracted by pushing and sliding i, and the front wheels 9 and 9 are rotated and steered via the spherical joint 11, the tie rod 12, and the knuckle arm 13.

Then, as described above, the center case 1
A central portion of the steering cylinder 10 and a front differential device are housed in the M, and the cylinder tube 10
As shown in FIG. 2, one of the recesses 10e formed in b is
The ring gear 15 is arranged so that it does not come into contact with the ring gear 15, and as shown in FIG. 5, the distance D between the center of the front axle case 1 (center line L1) and the center of the steering cylinder (center line L2) is as short as possible. Therefore, by arranging in this way, the piston rod 10a (center line L2) and the tie rod 12 during straight traveling are arranged.
And the crossing angle α ′ between the piston rod 10a ′ and the tie rod 12 ′ during turning (when the steering cylinder 10 is sliding) are reduced so that the maximum turning, that is, the piston rod 10a is extended most. Of the reaction force F of the tie rod 12 'to the piston rod 10a' side when the piston rod 10a 'is rotated, the component force F1 in the direction perpendicular to the piston rod 10a' is reduced so that the bending force applied in the direction perpendicular to the axial center of the piston rod 10a. Is kept small so that the operation of the steering cylinder 10 is not adversely affected.

[0013]

The present invention having the above-mentioned structure has the following effects. That is, the distance between the center of the front axle case and the center of the steering cylinder can be shortened, the crossing angle between the piston rod and the tie rod when the piston rod is extended is reduced, and the piston rod tends to bend. Since the component force can be suppressed to a small level, bending of the piston rod is prevented,
Prevents wear and galling of the sliding parts of the cylinder, improves safety and durability, ensures sufficient strength without notching the front axle frame, and reduces the bending force of the piston rod. , The force to push the tie rod to the left and right can be efficiently transmitted to the knuckle arm.

[Brief description of drawings]

FIG. 1 is a front view of front wheels and a front axle case.

FIG. 2 is a plan sectional view of a front axle case.

FIG. 3 is a side sectional view of the same.

FIG. 4 is a partial cross-sectional view of a plan view of a steering cylinder.

FIG. 5 is a plan view showing a connected state of a steering cylinder, a tie rod, and a knuckle arm.

[Explanation of symbols]

 1 Front Axle Case 10 Steering Cylinder 10a Piston Rod 10b Cylinder Tube 10e Recess 15 Ring Gear

Claims (1)

[Claims] 1. A front differential case and a part of a steering cylinder for power steering are housed in a front axle case of a four-wheel drive tractor, and a recess is formed on the outer circumference of a cylinder tube of the steering cylinder in the front axle case. A front wheel drive device for a tractor, characterized in that a ring gear of a front differential device is disposed so as to face the recess.