JPH068109B2 - Power steering device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a power steering device, and is used for a traveling vehicle such as an agricultural tractor.

(Prior Art) A power steering device for a tractor supports an axle swingably via a center shaft on an axle frame, and steerably attaches steering wheels to both ends of the axle via king pins. A cylinder tube of a power cylinder was attached in parallel with this, and a piston rod of this power cylinder was connected to a steering arm by a tie rod having a pair of joints.

(Problems to be solved by the invention) However, in the prior art, the tie rod is connected to the most advanced piston rod of the power cylinder, and since the distance between the left and right ends of the piston rod is long, the tie rod is short and the tread When adjusting, the adjustment distance cannot be lengthened.

This is because the tube of the power cylinder is fixed to the axle and the steering arm rotates, so that it must be connected by a tie rod having a joint in order to absorb it.

This causes problems such as difficulty in narrowing the tread and loss of steering force transmission to the steering arm.For example, in a narrow tractor such as a vineyard, the cutting angle is reduced. It is disadvantageous because the (steering angle) is large and the tread cannot be narrowed.

For this reason, a technique in which the power cylinder can be moved in three dimensions is disclosed in Japanese Utility Model Laid-Open No. 192772/1982.

That is, a U-shaped support tool with a series of upper and lower brackets is attached to the front side of the axle via a ball joint, and the power cylinder is movable between the upper and lower brackets by a pin in a long hole formed in the upper and lower brackets. It is attached to.

However, in the technique disclosed in this publication, since the combined movement of the power cylinder in the front-back direction and the vertical direction is due to the ball joint and the long hole, the amount of movement is small, and as a result, the allowable amount of three-dimensional movement during steering is small. There were challenges.

It is an object of the present invention to solve the above-mentioned problems by mounting a tube of a power cylinder on an axle so as to be rotatable in a three-dimensional direction on a center shaft.

(Means for Solving Problems) In the present invention, the axial center portion of the wheel 5 supporting the steerable wheels 2 so as to be able to steer around the kingpin at both ends has an axial center in the longitudinal direction of the vehicle body. Is swingably supported on the axle frame 6 via a center shaft 7 arranged in the center of the vehicle body,
A power cylinder 12 having left and right piston rods 15 and 16 slidably fitted in a cylinder tube 13 is attached to the axle 5 so as to be substantially parallel to the axle 5 and permit movement in three dimensions. Left and right piston rods 15, 16
In the power steering device in which the respective ends of the vehicle are interlockingly connected to the left and right steering arms 11, the first bracket 5A projecting forward is attached to the axle 5 at a portion which is unevenly distributed to the left or right of the center shaft 7. And a lower base end portion of a connecting arm 27 is fixed to the first bracket 5A via a support shaft 26 having an axis parallel to the axle 5.
A connecting arm 27 that can swing in the front-rear direction C about the fulcrum
And a second bracket 13A projecting forward are fixed to the cylinder tube 13 of the power cylinder 12, and a mounting shaft 2 having a spherical portion 22 is provided on the second bracket 13A.
1 is mounted on the axis of the center shaft 7 and orthogonal to the axis, and a mounting shaft 23A having a ball receiving seat 23 into which the ball portion 22 is fitted and slides is parallel to the support shaft 26. It is attached to the upper part of the connecting arm 27, and further, a shaft hole 15A is formed inside the shaft center of the left and right piston rods 15 and 16, and a tie rod shaft 28 is attached to this shaft hole 15A so that it can be adjusted for expansion and contraction. The left and right piston rods 15 and 16 are connected to the steering arm 11.

(Operation) When hydraulic pressure is supplied to the cylinder tube 13 of the power cylinder 12 from the control unit (valve) that is switched by the operation of the steering handle 4, the piston rods 15 and 16 are slid to operate the steering arm 11. Directional force is transmitted, and each steering arm 11 is rotated in the direction of arrow D in FIG. 2 to steer the steering wheels 2, 2.

The movement of the steering arm 11 makes an arc motion, and accordingly, the left and right and front and rear movements must be allowed, but the cylinder tube 13 allows the movement in the arrow C direction in FIG. However, the movement in the directions A and B shown in FIGS. 2 and 3 is allowed through the ball joint 22, and in particular, the movement in the direction C shown by the arrow is largely allowed by the connecting arm 27 about the support shaft 26. In addition, since it is allowed by the ball joint 24 as well, it is possible to allow a three-dimensional movement here and steer without being twisted.

Further, by this, the force in the axial direction of the piston rods 15 and 16 directly acts on the steering arm 11 to transmit power without loss.

Further, in order to adjust the tread, the insertion amount of the tie rod shaft 28 is adjusted in the shaft hole 15A of the piston rod 15, that is,
Coarse adjustment is possible by expanding and contracting.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In FIG. 5, 1 is a tractor, which is a pair of left and right front wheels 2,
It is a biaxial 4-wheel type having a pair of left and right rear wheels 3,
Is the steering wheel.

Reference numeral 4 is a steering handle, and a hydraulic control valve (control unit) (not shown) can be switched by the movement of the steering handle.

The front wheels 2 are attached to both ends of the axle 5 so as to be rotatable around the kingpins.

The front wheel 2 may be a steering wheel as well as a driving wheel. In this case, the axle 5 has a diff mechanism built therein, and a bevel gear mechanism or the like interlocking with the diff mechanism is used at both ends of the axle. Have.

In FIG. 1, reference numeral 6 denotes an axle frame, which has a center shaft 7. The center shaft 7 has its axis oriented toward the advancing axle (front-rear direction) of the tractor 1 and is rotatable about the axis of the axle frame 6. It is supported (suspended) and the axle 5 is attached to the center axle 7.
Is attached, and the axle 5 is pivotally pivoted on the center.

The axle 5 is composed of a box-shaped shaft portion 8 and both end shaft portions 9 which are inserted into the box-shaped shaft portion 8 by a nesting structure and can be elastically fixed by bolts 10 or the like. The end portions of the both end shaft portions 9 are bent backward in a plan view. The curved portion 9A is provided, and the steering wheel 2 is supported on the curved portion 9A side via a kingpin, and the steering arm 11 protrudes forward.

A power cylinder 12 is composed of a cylinder tube 13, a piston 14 fitted to the cylinder tube 13 and a pair of left and right piston rods 15, 16, and the cylinder tube 13 has liquid feed pipes 17, 18
Are communicated with each other, and the hydraulic pressure from the control unit is supplied to slide the piston 14 to operate the piston rods 15 and 16.

In the figure is a double action type, piston rod 1
5, 16 are connected at their ends to the corresponding steering arm 11 by a joint 19, but one piston rod is connected to the steering arm 11, and the steering arms 11 are connected to each other by tie rods. It may be one.

The tube 13 of the power cylinder 12 is substantially parallel to the axis of the axle 5 and is attached to the axle 5 side by a connector 20 so as to be swingable in three dimensions.

That is, as shown in FIG. 4, the connecting tool 20 has a ball portion 22 at the end of the mounting shaft 21, and the ball portion 24 is fitted into a ball receiving seat 23 so that a ball joint 24 can be swung. The mounting shaft 21 is inserted into the bracket 13A protruding from the tube 13 and attached with the nut 25. On the other hand, on the bracket 5A protruding forward on the axle 5,
A support shaft 26, which is substantially parallel to the axle 5 and the axial center, is rotatably inserted and attached to the upper end of an arm 27 having the support shaft 26 by fixing a shaft 23A of a ball seat 23. There is.

That is, the ball joint is placed on the vertical plane XX of the center shaft 7.
24 is provided, and the tube 13 is attached to the axle 5 by a connector 20 having a support shaft 26 on the horizontal plane Y-Y of the center shaft 7.

As a result, the power cylinder 12 is immovable in the axial direction of the axle 5, but is rotatable about the ball joint 24 in the A direction of FIG. 2 and the B direction of FIG. 1 is swung in the direction C in FIG. 1, and the swing of the steering arm 11 is followed by a three-dimensional movement.

Further, the piston rods 15 and 16 are connected at the end of the steering arm 11 on the extension of the axis and are connected by a joint 19, but in the present example, a tie rod shaft 28 having the joint 19 is connected by a fastener 29. ing. In this case, the piston rod 15,16
(However, only one is shown in the figure.)
15A is formed, and the tie rod shaft 28 is extendably inserted into the shaft hole 15A, and can be fixed by loosening and fastening the fastener 29.

Moreover, as shown in FIG. 6, the tie rod shaft 28 has a notch 28A formed on the outer periphery thereof at an axial interval to which the lock pin 29A of the fastener 29 engages, and the lock pin 29A is formed in this notch 28A.
Are engaged and fixed. A slit 15B is formed at the open end of the shaft hole 15A in the piston rods 15 and 16 to strengthen the fastening of the fastener 29.

In the illustrated example, the cylinder tube 13 is located above the axle 5, but it may be located below. The arm 27 having the support shaft 26 is shown as one, but the arm 27 is attached to the axle 5 with the support shafts 26 on both the left and right sides of the center shaft 7, and the ball joint 24 is supported on both sides. But it's okay. In addition, 24A is an elastic boot and 6A is a center shaft stopper.

In the above configuration, when hydraulic pressure is applied to the tube 13 of the power cylinder 12, the piston 14 slides to the left or right, and in this example, the steering arm 11 is pressed by one of the piston rods 15 and 16, On the other hand, the steering arm 11 is retracted so that the steering wheel 2 is steered at a predetermined turning angle.

In this steering, the swing of the swing arm 11 in the direction of the arrow D is corrected and absorbed by the above-described three-dimensional movement permission of A, B, and C, and the power cylinder 12 is not twisted.

Further, the tread adjustment is performed by loosening and tightening the bolts 10 so that the shaft portions 9 at both ends can be freely expanded and contracted, and this adjustment can be performed by the fasteners 29 and the tie rod shafts 28.

That is, the tie rod shaft 28 has a screw portion 28B, and a nut 28C is screwed into the tie rod shaft 28 for fine adjustment (a shaft having a turnbuckle structure may also be used). Loosen the fastener 29, tie rod shaft 28
This is performed by roughly adjusting the expansion / contraction length of the shaft hole 15A.

(Effects of the Invention) As described in detail above, according to the present invention, the first bracket 5A protruding forward is fixed to the axle 5 at a portion which is unevenly distributed on either the left or right side of the center shaft 7, Bracket 5A
And a lower base end portion of a connecting arm 27 via a supporting shaft 26 having an axis parallel to the axle 5 so as to be swingable in the front-rear direction C about the supporting shaft 26 as a fulcrum and extending upward. On the other hand, the second bracket 13A protruding forward is fixed to the cylinder tube 13 of the power cylinder 12, and the second bracket 1
A mounting shaft 21 having a ball portion 22 attached to 3A is mounted on the axis of the center shaft 7 and orthogonal to the axis, and a mounting shaft 23A having a ball seat 23 on which the ball portion 22 is fitted and slides. Is attached to the upper part of the connecting arm 27 in parallel with the support shaft 26, and further, a shaft hole 15A is formed inside the shaft center of the left and right piston rods 15 and 16, and the tie rod shaft 28 is freely adjustable in expansion and contraction in the shaft hole 15A. Attached to the piston rod 15, 16 via this tie rod shaft 28
Since this is characterized by being connected to the steering arm 11, it has the following advantages.

The strokes of the piston rods 15 and 16 can be increased, so that the power is sufficient even if the diameter of the cylinder tube 13 is reduced, and therefore the cylinder tube 13 can be mounted even in a narrow space.

The movement of the steering arm 11 is based on the support shaft 26 and the connecting arm 27.
Can be followed by the three-dimensional movement of the ball joint 24 between the connecting arm 27 and the second bracket 13C, and in particular, the cylinder tube 13 can be moved by the movement of the arm length of the connecting arm 27. Since the movement is allowed, the twisting is small, and the power to the steering arm 11 can be transmitted directly and surely without loss.

Further, the piston rod 15 has a shaft hole 15A formed therein,
Since the tie rod shaft 28 can be extended and fixed freely, the tread can be adjusted easily and surely.

Therefore, the steering wheel 2 has a large cutting angle and is useful when applied to the case where the tread is narrowed.

[Brief description of drawings]

Drawing shows an embodiment of the present invention, Fig. 1 is a side sectional view, Fig. 2 is a plan view, Fig. 3 is a front view, Fig. 4 is a sectional view of a ball joint, and Fig. 5 is a plan view of a tractor. , FIG. 6 is a partially cutaway sectional view of the power cylinder. 1 ... tractor, 2 ... steering wheel, 5 ... axle, 6 ... axle frame, 7 ... center axle, 11 ... steering arm, 12
...... Power cylinder, 13 ...... Cylinder tube, 15,16
...... Piston rod, 15A ...... Shaft hole, 20 ...... Coupling, 22
...... Ball joint, 26 …… spindle, 28 …… tie rod shaft.

Claims (1)

[Claims] 1. An axially central portion of an axle (5) supporting steerable wheels (2) around the kingpin at both ends thereof so as to be steerable,
It is swingably supported on the axle frame (6) via the center shaft (7) which is located in the center of the vehicle body and has the axis in the longitudinal direction of the vehicle body, and is swingable on the cylinder tube (13). The power cylinder (12) having the left and right piston rods (15) (16) fitted therein is attached to the axle (5) while being substantially parallel to the axle (5) and allowing movement in three dimensions. Connect the left and right steering arms (11) to the ends of the piston rods (15) (16).
A power steering device that is interlockingly connected to the first bracket that protrudes forward on the axle (5) at a portion that is unevenly distributed on either the left or right side of the center shaft (7).
(5A) is fixed, and the lower base end portion of the connecting arm (27) is attached to the first bracket (5A) via a support shaft (26) having an axis parallel to the axle (5). ) As a fulcrum and provided with a connecting arm (27) extending upward so as to be swingable in the front-rear direction (C), while the second bracket (13A) protruding forward to the cylinder tube (13) of the power cylinder (12). ) Is fixed to the second bracket
The mounting shaft (21) having the ball portion (22) on (13A) is mounted on the axis of the center shaft (7) and orthogonal to the axis, and the ball portion (22) is fitted and slides. Mounting shaft (23A) with a ball seat (23)
Is attached to the upper part of the connecting arm (27) so as to be parallel to the support shaft (26), and the shaft holes (1
5A) is formed, the tie rod shaft (28) is attached to the shaft hole (15A) so that it can be adjusted for expansion and contraction, and the piston rods (15) and (16) are attached to the steering arm (11) via the tie rod shaft (28). The power steering device is characterized by being connected to.