JPH0525371Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a hydraulic control device for raising and lowering a lift arm in an agricultural tractor by operating a hydraulic control valve.

BACKGROUND ART Conventionally, in agricultural tractors, a hydraulic control device for raising and lowering a lift arm by operating a hydraulic control valve is already known, as described in, for example, Japanese Utility Model Application Publication No. 59-42017.

Problems that the invention aims to solve By the way, in the conventional hydraulic control device for agricultural tractors as described above, the hydraulic control valve and the holder of the link mechanism that operates the spool are separately attached to the hydraulic lift case. Therefore, it is difficult to assemble the hydraulic control valve and the link mechanism, and to make adjustments after assembly, and the operation tends to be unstable due to poor adjustment.

Therefore, in view of these drawbacks of the conventional ones, the present invention aims to structurally integrate the hydraulic control valve and the link mechanism that operates the spool, thereby making it easier to assemble the hydraulic control valve to the hydraulic lift case. It is an object of the present invention to provide a hydraulic control device for an agricultural tractor that can eliminate the need for adjustment after assembly.

Means for Solving the Problems The present invention has the following technical means for achieving its purpose. That is, the hydraulic control device for an agricultural tractor according to the present invention includes a lift cylinder for raising and lowering a lift arm, and a hydraulic control valve thereof having a spool for raising and a spool for lowering in parallel. A flat plate-shaped holder is fixed to the lower surface of the hydraulic control valve, a horizontal link connected to the spool in the upward direction is attached to the holder so as to be slidable in the operating direction of the spool, and a position control link and a tiller are attached to the horizontal link. The depth adjustment link is pivoted so as to be horizontally swingable with an extension of the opposing center positions of the spool in the raising direction and the spool in the lowering direction as a pivot point, and the position control link has a depth adjustment link that is engaged with both ends of the depth adjustment link. The tilling depth adjustment link uses the tilling depth adjusting arm and the sensor arm engaged at both ends as pivoting fulcrums, and the tilling depth adjustment link uses the tilling depth adjustment arm and sensor arm engaged at both ends as pivoting fulcrums, and serves as a pivot point for each horizontal swing. As well as sliding the horizontal link by moving in the swinging direction,
It is characterized in that the spool in the upward direction is connected to the spool in the downward direction via a connecting member.

Function When raising or lowering the lift arm of an agricultural tractor, the position control link and plowing depth adjustment link, which are pivotally connected to the horizontal link, swing horizontally as swinging fulcrums at both ends, so that the pivoting points of both links are aligned horizontally. Slide the link in the direction of spool operation. Along with this, the spool in the upward direction connected to the horizontal link operates together with the spool in the downward direction connected through the connecting member, but the pivot point is the opposite center of the spool in the upward direction and the spool in the downward direction. Since the spools are on an extension of the position, the spools in the upward direction and the spools in the downward direction, which are located on both sides of the pivot point, operate stably and accurately. A horizontal link that operates the spool is slidably attached to a flat holder fixed to the bottom surface of the hydraulic control valve, so the position control link and plowing depth adjustment link are pivotally connected to the hydraulic control valve and the horizontal link. The attached link mechanism has an integrated structure, making it easy to assemble to the hydraulic lift case. Furthermore, after assembly, there is no need to adjust the hydraulic control valve and link mechanism.

Example Embodiments of the present invention will be described with reference to the drawings.

1 is an agricultural tractor, 2 is a hydraulic lift case, 3 is a lift arm, 4 is a position control lever, and 5 is a plowing depth adjustment lever.

The lift arm 3 is fixed to both ends of a shaft 6 that is pivotally supported at the rear upper part of the hydraulic lift case 2, and the shaft 6 is connected to a lift cylinder 9 via a lift power arm 7 and a piston rod 8 fixed to it. connected to a piston 10 of
The lift arm 3 is raised and lowered by the piston 10. 11 is a hydraulic control valve, and this hydraulic control valve 1
1 is interposed in the hydraulic circuit of the hydraulic lift case 2. The hydraulic control valve 11 is equipped with a spool 12 in the upward direction and a spool 13 in the downward direction in parallel, and the spool 12 in the upward direction has a horizontal link 14, which is the base of the link mechanism, on its hanging portion 15. The spool 13, which is fixed with a nut and extends in the downward direction, is connected to the spool 12 via a connecting member 16 that engages only in the downward direction. Reference numeral 17 denotes a flat plate-shaped holder, which is fixed to the lower surface of the hydraulic control valve 11 and protrudes in the direction in which the spools 12 and 13 protrude. It is engaged with a pin 19 implanted in the spools 12 and 13, and is slidable in the operating direction of the spools 12 and 13. A spool 1 is provided between the spring hook hole 20 of the horizontal link 14 and the tip of the holder 17.
A spring 21 that pulls 2 and 13 in the downward direction is applied. Further, 22 is a position control link, 23 is a plowing depth adjustment link, and both links 2
2 and 22 are spools 12 disposed below and above the horizontal link 14 and parallel to each other in the upward direction.
It is pivotally connected to the horizontal link 14 by a pin 24 as a pivot point provided on an extension of the central position facing the spool 13 in the lowering direction. Then, a position control arm 26 that rotates integrally via the pivot shaft 25 of the position control lever 4 and the link 32 is engaged with the lowering direction edge of the position control link 22 on one end side. One end of a feedback arm 28 constituting a feedback mechanism 27 is engaged with the lowering direction edge of the other end of the link 22 . The feedback arm 28 is rotatable about a fulcrum 29, and the other end is connected to the lift power arm 7 via a feedback link 30. This feedback mechanism 2
7. It is housed in the hydraulic lift case 2. The operation-related positions of the lift power arm 7, the feedback link 30, and the feedback arm 28 will be explained later along with their functions. on the other hand,
A tilling depth adjusting arm 33 that rotates together with the pivot shaft 31 of the tilling depth adjusting lever 5 is engaged with the edge in the lowering direction on one end side of the tilling depth adjusting link 23.
A sensor arm 34 is engaged with the edge of the other end of 3 in the downward direction. A sensor lever 35 is connected to the sensor arm 34.
is connected to the rotary rear cover of the rotary tiller by a wire (not shown).

In the hydraulic control device configured as described above, the position control lever 4 is operated when the lift arm 3 is raised or lowered, but if the position control lever 4 is now operated in the downward direction, the position control link 22
swings in the downward direction using the engagement point with the feedback arm 28 as a fulcrum, and as the pivot point 24 moves in the swinging direction, the sliding horizontal link 14 slides onto the spool 12 of the hydraulic control valve 11. , 13 are set at the lowered position, the lift cylinder 9 drives the lift arm 3 in the direction of lowering it, and the lift arm 3 is lowered. At the same time, as the lift power arm 7 rotates, the feedback arm 2 of the feedback mechanism 27
8 swings the position control link 22 in the upward direction using the engagement point with the position control arm 26 as a fulcrum, so that when the spools 12 and 13 of the hydraulic control valve 11 return to the intermediate position, the lift arm 3 Stop. The operation for raising the lift arm 3 is similar to the operation for lowering it, except that the direction of operation is reversed.

In addition, when the tilling depth adjustment lever 5 is operated, the tilling depth adjustment link 23 swings via the tilling depth adjustment arm 33 to adjust the spool 1 of the hydraulic control valve 11.
2 and 13 are activated to adjust the plowing depth of the rotary tiller. The plowing depth state is automatically maintained by the plowing depth adjustment link 23 being swung by the related operation of the sensor lever 35 interlocked with the rotary rear cover and the plowing depth adjustment arm 33.

By the way, as mentioned above, the holder 17 is attached to the hydraulic control valve 11, and a link mechanism consisting of the position control link 22 and the plowing depth adjustment link 23, which have the horizontal link 14 as a base, is attached to the holder 17, and the link mechanism is attached to the holder 17. are integrated, so the hydraulic control valve 11
The work of assembling the hydraulic lift case 2 into the hydraulic lift case 2 is easy. And the pivot point 2 on which the horizontal link 14 slides
4 is on the extension line of the opposing center position of the spool 12 in the raising direction and the spool 13 in the lowering direction, and the spool 12 in the raising direction connected to the horizontal link 14 has a lowering direction on the other side of the pin 24. Since the spools 13 are connected via the connecting member 16, there is no need to adjust the relative position between the spools 12, 13 and the link mechanism, and both spools 12, 13 can always be operated stably and accurately. I can do it. Further, the holder 17 has a flat plate shape, and can protect the link mechanism when the hydraulic control valve 11 is assembled or removed.

Effects of the Invention In short, the present invention provides a hydraulic control system for an agricultural tractor, which includes a lift cylinder for raising and lowering a lift arm, and a hydraulic control valve for the hydraulic control valve, in which a spool for raising and a spool for lowering are arranged in parallel. A flat plate-like holder is fixed to the bottom surface of the control valve, and a horizontal link connected to the spool in the lifting direction is attached to the holder so as to be slidable in the operating direction of the spool, and a position control link and a plowing depth adjustment link are attached to the horizontal link. and are pivoted so as to be horizontally swingable with an extension of the opposing centers of the spool in the raising direction and the spool in the lowering direction as a pivot point, and the position control link is a position control arm engaged with both ends of the spool. and the feedback arm as swinging fulcrums, and the tilling depth adjustment link uses the tilling depth adjustment arm and the sensor arm engaged at both ends as swinging fulcrums,
The horizontal link is caused to slide by the movement of the pivot point in the swinging direction with each horizontal swing, and the spool in the downward direction is connected to the spool in the upward direction via a connecting member, so that the spool of the hydraulic control valve is operated by a horizontal link that slides by the swinging of the position control link and plowing depth adjustment link, but the horizontal link is attached to a bracket fixed to the bottom of the hydraulic control valve, and the horizontal link is horizontal. A position control link and a plowing depth adjustment link are pivotally attached to the link, with the pivot point being an extension of the opposing center position of the spool in the raising direction and the spool in the lowering direction, and the sliding horizontal link connects the connecting member. Since the upward spool and downward spool connected through the spool are operated simultaneously, the hydraulic control valve and the link mechanism that operates the spool can be structurally integrated, and the hydraulic control valve This simplifies assembly to the hydraulic lift case, eliminates the need for adjustment after assembly, and allows the spool in the upward direction and the spool in the downward direction to always operate stably and accurately. be.

[Brief explanation of the drawing]

The drawings show an embodiment of the hydraulic control device for an agricultural tractor according to the present invention, in which FIG. 1 is an overall perspective view of the agricultural tractor, FIG. 2 is a plan view of the hydraulic device portion, and FIG. Fig. 4 is a bottom view of the hydraulic system, Fig. 5 is a sectional view taken along - line in Fig. 4, Fig. 6 is a sectional view taken along - line in Fig.
The figure is a plan view of the part shown in Fig. 6, and Fig. 8 is a plan view of the part shown in Fig. 5.
It is a sectional view taken along the - line in the figure. 1...Agricultural tractor, 2...Hydraulic case, 3...
... Lift arm, 4 ... Position control lever, 5 ... Depth adjustment lever, 6 ... Shaft, 7 ... Lift power arm, 8 ... Piston rod, 9 ... Lift cylinder, 10 ... Piston, 11 ... ...Hydraulic control valve, 12...
Spool in the upward direction, 13... Spool in the downward direction, 14... Horizontal link, 15... Its hanging part,
16... Connecting member, 17... Holder, 18... Long hole, 19... Pin, 20... Spring hanging hole, 21...
Spring, 22...Position control link,
23... Cultivation depth adjustment link, 24... Pin, 25...
... Pivot shaft, 26 ... Position control arm, 27 ... Feedback mechanism, 28 ... Feedback arm, 29 ... Fulcrum, 30 ... Feedback link, 31 ... Pivot shaft, 32 ... Link, 33... tilling depth adjustment arm, 34... sensor arm, 35... sensor lever.

Claims (1)

[Scope of utility model registration request] a lift cylinder that raises and lowers the lift arm;
In a hydraulic control device for an agricultural tractor in which the hydraulic control valve is equipped with a spool in the upward direction and a spool in the downward direction in parallel, a flat holder is fixed to the lower surface of the hydraulic control valve,
A horizontal link connected to the spool in the upward direction is attached to the holder so as to be slidable in the operating direction of the spool,
A position control link and a plowing depth adjustment link are pivoted to the horizontal link so as to be horizontally swingable with the pivot point being an extension of the opposing center positions of the spool in the raising direction and the spool in the lowering direction. The link uses the position control arm and the feedback arm that are engaged at both ends as pivot points, and the tillage depth adjustment link uses the tillage depth adjustment arm and the sensor arm that are engaged at both ends as pivot points. , Agricultural use characterized in that the horizontal link is slid by the movement of the pivot point in the swing direction accompanying each horizontal swing, and the spool in the downward direction is connected to the spool in the upward direction via a connecting member. Tractor hydraulic control device.