JPH0376882B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to a link mechanism for a draft control constructed in a large tractor.

(b) Prior Art Conventionally, a draft spring case has been attached to the rear of a hydraulic case, and the tip of a spring guide pivotally connected to the upper end of a top link hitch is passed through the draft spring case and protrudes forward. Techniques that can also be used as feedback links are known.

For example, there is a technique described in Japanese Unexamined Patent Publication No. 138301/1983.

(C) Problems to be Solved by the Invention However, in the above-mentioned prior art, in order to facilitate the connection between the spring guide that slides back and forth and the draft feedback arm that rotates back and forth,
The rotating linkage was long, and the draft feedback arm was also long.

In addition, as in the conventional technology, there is a
When a draft spring case or draft spring was installed, the overall length of the tractor became longer.

The present invention solves the above-mentioned problems.

(d) Means for solving the problems The problems to be solved by the present invention are as described above.
Next, means for solving the problem will be explained.

A draft spring case 2 is provided on the upper surface of the hydraulic case 1, and a spring guide 7 is provided that penetrates the inside of the draft spring case 2 and projects forward. A draft spring is interposed between the spring guide 7 and the forwardly protruding portion of the draft spring case 2, and the draft feedback arm 18 which is vertically disposed at the front side of the hydraulic case 1 so as to be rotatable back and forth. A link 15 provided with two pivot shafts 14 and 16.
One of the two pivot shafts 14 is pivoted to the spring guide 7 side, and the other pivot shaft 16 is pivoted to the draft feedback arm 18 side. This constitutes a rotation link device B, which is connected in such a manner that the spring guide 7 can be moved in parallel back and forth and the feedback arm 18 can be rotated back and forth.

(E) Embodiment The problems to be solved by the present invention and the means for solving them are as described above. Next, the structure of the embodiment shown in the attached drawings will be explained.

FIG. 1 is a left side view of the hydraulic case, FIG. 2 is a left sectional view, and FIG. 3 is a rotating link device B between the spring guide 7 and the feedback arm 18.
Fig. 4 is a front sectional view of the feedback arm section, Fig. 5 is a front sectional view of the control bar section, and Fig. 6 is a link between the feedback arm section and the control bar section. FIG.

The hydraulic case 1 is mounted and fixed on the upper processed surface of the rear axle case or transmission case of an agricultural tractor.

The upper surface of the hydraulic case 1 is machined to be flat so that the machined surface is opened, and a draft spring case 2 which also serves as a lid is placed and fixed thereon. A control valve V is attached and fixed to the lower surface of the draft spring case 2, and after the control valve V is assembled to the draft spring case 2, it is inserted and fixed as an integral part from above.

Feedback links and operation links for draft control and position control are first installed from the side inside the hydraulic case 1, and when the control valve V is inserted from above,
There is no need to assemble it with bolts or pins, and it is configured so that it can be controlled simply by contact with links.

Therefore, the control valve can be assembled by simply inserting it later. A pivot shaft 10 for a top link hitch 3 is provided on the rear protrusion 1a of the hydraulic case 1, and the top link hitch 3 is connected to the connecting hole 3.
Draft forces in both positive and negative directions are generated by pushing and pulling the top links pivotally supported by a and 3a.

This draft force is transmitted to the spring guide 7 through the pivot shaft 32 and ring 31 at the upper end of the top link hitch 3. If the draft force acting on the work machine is directly fed back and transmitted to the control valve V, the control valve will be destroyed, so it is buffered by the double draft springs 29 and 30 and transmitted as a weak force to the feedback arm 18. be.

Conventionally, the draft spring case was provided on the rear or side surface of the hydraulic case, and the spring guide 7 was only guided within the spring case and was not also used as a feedback link, so a separate top link hitch 3 was required. The draft force was transmitted to the draft feedback arm 18 through a long link.

In the present invention, a draft spring case 2 is provided on the upper surface of the hydraulic case, and a spring guide 7 is provided passing through the draft spring case 2, and the spring guide 7 is used as one of the links and protrudes to the front end of the hydraulic case. A rotation link device B is provided between the feedback arm 18 at the front side of the hydraulic case 1.
are provided on the upper surface of the hydraulic case 1 and are arranged in series.

As shown in Fig. 3, the rotation link device B has an arm 13 fixed to the tip of the spring guide 7 with two nuts, a cylindrical body 13a welded and fixed to the tip of the arm 13, and a pivot member 13a attached to the cylindrical body 13a. The support shaft 14 is loosely fitted, the pivot shaft 14 is fixed to the link 15, and the link 1
A pivot shaft 16 is fixed to the rear end of the pivot shaft 1.
6 is loosely fitted into the cylindrical body 17 of the feedback arm 18. Therefore, the two pivot shafts 14 and 16 connect the longitudinal translation of the spring guide 7 and the longitudinal rotation of the feedback arm 18.

Furthermore, the draft force of the top link hitch 3 is transmitted from the feedback arm 18 to the ball locking body 64a via the outer cylinder 64 shown in FIG. 4. A ball 65 is fitted into a hole in a ball holding cylinder 66 that is loosely fitted around the outer periphery of the position feedback shaft 20, and this ball 65 is inserted into the ball locking body 6.
Both of them can be fitted into the fitting hole 64b of 4a and the fitting hole 20a of the positive feedback back shaft 20, and both work integrally only when they are fitted.

That is, when the draft setting lever 61 in FIG. 5 is rotated in the upward direction, the lift arm 5 rises.

In the case of FIG. 6, the lift arm is shown in a raised state as shown in FIG. 1, and the position feedback shaft 20 is rotated by the feedback mechanism of the position control, and the position feedback shaft 20 is Fitting hole 20a and ball 65
Since the insertion holes of the ball locking body 64a are aligned and the arm 67 is urged in the direction of arrow a by the return spring of the control valve V, the ball holding cylinder 66 has not been engaged with the ball until then. Although it was locked between the stopper 64a by the ball 65 and could not be moved, the position feedback shaft 20
Since the fitting hole 20a has come to the inside, the ball is pushed into the fitting hole 20a, and the shaft 20 and ball holding cylinder 66 are integrated, and rotate as the lift arm is raised.

By rotating in the direction of arrow a, the arm 67 moves and retreats the position control bar 74 in the neutral direction via the arm 69, and stops when the control bar becomes neutral.

When lowering the draft setting lever 61, when the draft setting lever 61 is lowered, the draft control bar 75 is lowered rearward, the control valve V is lowered, and the lift arm 5 is lowered.
It's also going down.

The holding cylinder 66, which is integrated with the position feedback shaft 20 via the ball 65, is also connected to the arrow a.
The draft control bar 75 is rotated in the opposite direction, and the draft control bar 75 is pushed forward in the upward direction by the arm 69, and the lowering stops when the center of the draft control bar becomes neutral.

Before that, the insertion hole 64b of the ball locking body 64a on the draft control side and the insertion hole 20a of the position feedback shaft 20 are aligned. Since the ball holding cylinder 66 is biased by the spring of the control valve V, the ball 65 is pushed into the fitting hole 64b and integrated with the ball locking body 64a.
The rotation of the arm 67 from this point on is stopped.

If the center of the draft control bar 75 still does not return to neutral, the lift arm 5 continues to lower and the positioning arm 70 moves forward.
This position control bar 74 is used to return to neutral.

In conventional draft control devices,
The draft setting lever 61 was used only to set the draft sensitivity, and it was impossible to raise the lift arm significantly to move around the edge of the field.

This is because only the rotation of the top link hitch 3 is transmitted to the draft control bar 75, and after the work equipment is lifted onto the lift arm, the feedback link is pulled in the positive direction due to the weight of the work equipment. Even if the lift arm is pulled up and the lift arm is then rotated upward, the amount of upward rotation of the lift arm will not be fed back to the draft control bar, so even if the lift arm goes up, the control valve will still be in the "up" position and the relief valve will not be activated. This is because it will continue to blow out.

In the present invention, the insertion hole for the ball 65 is set from 64b to 2.
After the lift arm 5 has rotated above a certain level by moving it to 0a, the draft feedback arm 67 for draft control is activated.
and a position feedback shaft 20 are integrated, and the raising of the lift arm 5 is fed back to the draft control bar 75.

Then, the lift arm is lowered, and from the angle where the balls 65 and the insertion holes 20a, 64b are aligned, the draft feedback arm 67 is also connected to the outer cylinder 6.
4 and return to the draft feedback system.

The above is done by operating the draft setting lever 61.
The structure allows the lift arm to raise and rotate significantly when moving around the edge of the field, and draft control and position control can be switched only in this area.

Other draft control and position control are the same as conventional ones.

Feedback for the draft control is transmitted from the draft feedback arm 67 to the arm 69 via the pin 68 and the elongated hole, and is rotated back and forth through the horizontally installed draft control bar 75 from the ball joint 73 of the hole 69a.

On the other hand, the setting of the draft amount by the operator and the raising and lowering for turning around the field edge are transmitted from the draft setting lever 61 to the shaft 78, the arm 81, and the ball joint 77 to the right end of the draft control bar 75, thereby performing draft control.

Further, the feedback of the position control is transmitted from the inner arm 11 of the lift arm 5 to the arm 19 via the link 12, and the feedback shaft 20 shown in FIG. 22, the arm 70 of pure position control is rotated via the link 21 and the arm 23. A position control bar 74 is moved back and forth from a ball joint 72 of an arm 70.

On the other hand, when the position setting lever 60 is rotated by the operator, one end of the position control bar 74 is moved back and forth from the cylinder shaft 79, the arm 80, and the ball joint 76.

The control bars 75, 74 are held by ball joints 73, 72, 77, 76 at both ends, and these parts are configured so that they do not come off. Joint part 75 on joint 73, 72 side
It is absorbed by the elastic part provided between a and 74a.

The small diameter portions at the center of the two control bars 74 and 75 are in contact with the contact pin 58 of the control valve V.

The flow of pressure oil according to the present invention will be explained in detail.

There is a pressure oil inlet in front of the relief valve 46 of the cylinder head 4, and the pressure oil that enters from there enters the spool 57 of the auxiliary control valve 6 shown in FIG. 4 and can be used for other working machines. The unused pressure oil is sent from the piping 47 to the oil passage 40 of the draft spring case 2 shown in FIG. 2, and enters the control valve V from there.

Pressure oil controlled by the control valve V enters the hydraulic cylinder 24 from the oil passage 41 through the slow return valve and stop valve 39 in the cylinder head. The piston 25 is pushed up by the pressure oil, and the lift arm 5 is rotated upward by the connecting rod 26, arm 27, and shaft 28. 38 is a safety valve.

A is an oil reservoir that stores drain oil from the control valve V, the safety valve 38, and the relief valve 46. 36 is a connecting rod lubricating pipe, 44 is an oil supply hole for the hydraulic brake, and 45 is a lubricant oil hole for a hydraulic clutch device in the transmission case or rear axle case.

In FIG. 2, a stopper 33 is provided on the pivot shaft 63 of the top link hitch 3 to stop the draft control.

The stopper 33 is urged toward the locking pin 35 by a fulcrum crossing spring 62, and is released by the fulcrum crossing spring 62 when the release lever 34 is rotated upward.

(F) Effects of the Invention Since the present invention is configured as described above, it has the following effects.

First, since the draft spring case 2 is arranged overlappingly on the upper surface of the hydraulic case 1, the draft spring case 2 and the draft spring can
This eliminates the need for the hydraulic case 1 to be disposed protruding rearward, making it possible to shorten the total length of the tractor.

Second, in order to increase the rotation angle of the lift arm 5 for feedback, the position feedback arm 19 must be placed at a position in front away from the lift arm 5. Further, since the mechanism is such that the control valve V can be operated by switching between the draft feedback arm 18 and the position feedback arm 19, the draft feedback arm 18 is also operated by the position feedback arm. It is necessary to locate the pivot at approximately the same position as 19. Therefore draft feedback arm 18
However, it is inevitably placed at the front of the hydraulic case 1.

In such a case, when a draft spring or a spring guide is arranged at the rear of the hydraulic case 1 as in the past, a long feedback link is interposed between the spring guide and the draft feedback arm. However, in the present invention, the spring guide 7 inside the draft spring case 2 placed on the top surface of the hydraulic case 1 also serves as this long feedback link, so there is no need to provide a separate long link. It was.

Thirdly, the front end of the spring guide 7 is located in the front part of the hydraulic case 1 and near the draft feedback arm 18, and there is no space between the spring guide 7 and the draft feedback arm 18 in the front and rear. Since the rotation link device B is installed to change the sliding direction into forward and backward rotation, it is possible to input signals even though there is a short distance between the spring guide 7 and the draft feedback arm 18. It was.

[Brief explanation of drawings]

FIG. 1 is a left side view of the hydraulic case, FIG. 2 is a left sectional view, and FIG. 3 is a rotating link device B between the spring guide 7 and the feedback arm 18.
Fig. 4 is a front sectional view of the feedback arm section, Fig. 5 is a front sectional view of the control bar section, and Fig. 6 is a link between the feedback arm section and the control bar section. FIG. A... Oil pool, B... Rotating link device, 1...
... Hydraulic case, 2 ... Draft spring case, 7 ... Spring guide, 18 ... Draft feedback arm, 29, 30 ... Draft spring.

Claims (1)

[Claims] 1 A draft spring case 2 is provided on the upper surface of the hydraulic case 1, and a spring guide 7 extends forward through the draft spring case 2.
A draft spring is interposed on the outer periphery of the part where the spring guide 7 passes inside the draft spring case 2, and the spring guide 7 protrudes forward of the draft spring case 2 and in front of the side surface of the hydraulic case 1. A link 15 with two pivot shafts 14 and 16 is provided between the draft feedback arm 18 and a draft feedback arm 18, which is vertically installed in a vertically rotatable manner.
One of the two pivot shafts 14 is pivoted to the spring guide 7 side, and the other pivot shaft 16 is pivoted to the draft feedback arm 18 side. A draft control device for an agricultural tractor, characterized in that the spring guides 7 and 18 form a rotation link device B, and are connected in such a manner that a spring guide 7 can be moved back and forth in parallel and a feedback arm 18 can be rotated back and forth.