JPH01157301A - Device for driving lift arm of agricultural tractor - Google Patents

Abstract

PURPOSE:To prevent floating of a machine body or stopping of an engine, by setting lowering speed by lowering operation of a manual operating lever of a position control valve at a low speed on the lowering side of the set position. CONSTITUTION:An operating lever 20 is operated to the lowering side (D) and frictionally held by belleville springs 22 and nuts 23 at an optional position to rotate an arm 24 and an operating shaft 13 of a position control valve by elastic force of a helical spring 25. When an engaging pin 30 is brought into contact with the end of a slot member 31, the arm 24 is slowly actuated by a damper mechanism 39. Thereby a rotary tiller is lowered at a low speed and landed thereafter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lift arm drive device for an agricultural tractor configured to be controlled by a hydraulic cylinder collage mechanical position control valve for lifting and lowering the lift arm drive.

[Prior art] In the conventional drive device described above, for example,
As shown in Publication No. 52212, when adjusting the descending speed of the lift arm, the flow area of the oil drain passage in the hydraulic cylinder is changed using a screw-turning type artificial control valve. It had a structure.

[Problem that the invention seeks to solve]

Therefore, if the adjusted descending speed is too fast, when lowering while driving a drive-type working device such as a rotary tiller after turning the headland, the rotary tiller will quickly dig into the field and the front side of the machine will be damaged. The engine speed may increase by y+%, or a sudden increase in load may cause the engine to stall.
If the descending speed is slow, the above problem can be avoided, but on the other hand, there is a problem that the descending time is too long and the work efficiency is reduced.

Therefore, skilled workers should set the lowering speed to a high level, operate the lever for operating the position control valve quickly at the initial stage of the lowering, lower the low tiller at high speed, and lower the lever from near the field. The rotary tiller is slowly lowered and the rotary tiller enters the field at low speed, but this operation is done while controlling the machine and visually checking the descending status of the rotary tiller. It was quite difficult.

The present invention automatically reduces the descending speed of the lift arm on the lowering side from the set position even when the lever is operated quickly to lower the lift arm. The purpose is to prevent problems such as lifting of the engine and stalling of the engine.

[Failure to solve the problem]

The present invention is characterized in that, in the lift arm driving device of an agricultural tractor having a buying configuration, the manual operation lever for the position control valve can be operated in advance only in the downward operation direction with respect to the operation shaft of the valve; The operating shaft is configured to be able to be held at any operating position, and the operating shaft is biased in the downward operating direction by a spring so that the operating shaft does not rotate following the operating lever, and the operating shaft is lowered from the set position of the operating shaft. A damper mechanism is provided to suppress the following rotation speed, and its functions and effects are as follows.

[Function] In other words, even when the manual operation lever is quickly operated to the desired plowing depth position in order to lower the lift arm, the rotation speed of the operation shaft is lowered by the damper mechanism on the lowering side than the set position. Since the lift arm is restrained and rotates slowly, the lift arm also descends slowly. Furthermore, since the operating shaft is structured to follow the manual operating lever using a spring, it rotates quickly until it reaches the set position.

〔Effect of the invention〕

Therefore, when lowering the working device connected to the lift arm from the elevated position above the field to the desired plowing depth position,
It descends at a relatively high speed until just before it hits the ground.
Since the speed is low near the point of landing, there is no unnecessary waiting time and work efficiency is improved.
This eliminates the need for the aircraft to plunge violently into the ground, making it possible to prevent the aircraft from lifting off or stalling.

〔Example〕

As shown in Figure 8, the rotary tiller (B) can be raised and lowered via a three-point link device consisting of left and right lower links (1), (1) and a top link (2) at the rear of the tractor (A). The left and right lift arms (4), which are connected to the
4) respectively, a lift rod (5).

The left and right lower links (1) and (1) are interlocked and connected via (5) to form a riding type cultivator.

As shown in FIGS. 4 and 5, the lift arm (4
), (4) and the lift rods (5), (5) have a structure that allows the fulcrum pin (6) with a head to be inserted through it to prevent it from coming out, and the fulcrum pin head (6a) is It is formed into a flat ellipse shape and is configured to slide only between it and a joint member (7) made of hard rubber. Furthermore, as shown in FIGS. 6 and 7, the connecting portion between the lower link (1) and the transmission case (8) also has a structure in which a headed fulcrum pin (9) is inserted therethrough to prevent it from coming out. It becomes.

As shown in Fig. 3, a position control valve (11) is installed on the lower surface of the storage case (10) of the lifting hydraulic cylinder (3), and the sliding spool (12) of the valve (11) is lowered. A valve operating shaft (13) for switching to position (d), neutral position (n), and raised position (u)
) is supported through the right side wall of the storage case (10), and the spool (1
2) is provided with a spool operating arm (14) pivoted at the end thereof. The lower end of the control arm (15), whose upper end is integrally rotatably connected to the operating shaft (13), is connected to the right end of the spool operating arm (14) via a ball joint, and the storage case (10 ), and the feedback lever (17) attached to the outer end of the case is connected to the left lift via the feedback iron (18). A feedback arm (19) which is interlockingly connected to the arm (4) and whose upper end is rotatably connected to the feedback rotating shaft (16) is attached to the left end of the spool operating arm (14) via a ball joint. The height of the tilling device (B) relative to the tractor is set to the valve operating shaft (
A feedback type link mechanism is configured to automatically operate the valve spool (12) to return to the neutral position (N) when the height is set based on the rotational position of the valve spool (13).

Then, the manual operation lever (20) for the position control valve (11) is connected to the operation shaft (13).
In contrast, the lift arm is configured so that it can be operated in advance only to the lowering side (D) and can be held at any operating position, and the operating shaft (13) is configured to rotate following the operating lever (20). It is configured. That is, as shown in FIG. 2, the operating lever (20) is loosely fitted onto the operating shaft (13), and the boss portion (20a of the operating lever (20)
) and a reinforcing stay (21) that is fitted around the operating shaft (13) so as to be relatively rotatable, and a disc spring (22) is interposed between the reinforcing stay (21) and
By tightening and pressing a nut (23), the operating lever (20) can be frictionally held at any operating position. Then, an arm (24) for rotating the operating shaft (13) is provided on the side of the operating lever (20), and this arm (24) is fixed to the operating shaft (13), and this arm (24) and the operating lever ( 20), and the operating axis (13
), and then wind the helical spring (25) around the helical spring (2
The arm (24) and the operating shaft (13) are configured to follow the rotation of the operating lever (20) toward the downward direction (D) by the spring elastic force of 5).

When the operating lever (20) is operated to the upward side (U), the locking piece (26) comes into contact with the arm (24) and rotates in conjunction with the arm (24).

Further, an operating shaft (13) is provided on the free end side of the arm (24).
A damper mechanism (39) is linked to suppress the follow-up rotation speed from the set position to the downward side. That is, as shown in FIG. 1, a piston (78) is slidably provided in a case (27) containing hydraulic oil (I,), and the arm (78) is provided at the end of the piston rod (29). A long hole member (31) into which a retaining bottle (30) installed upright is inserted is extended from the piston (28), and a small amount of hydraulic oil (L) is inserted into the piston (28) when the arm (24) moves downward. ), and is provided with a valve body (33) that closes when the piston (28) moves in the downward direction and opens when it moves in the upward direction. (13)
A damper mechanism (39) of a hydraulic hole is configured to suppress the rotation speed toward the downward direction.

In the above configuration, when the low tillage device (B) is moved up and down when turning the furrow during tilling work, when the operation lever (20) is quickly swung toward the ascending side (11), the locking operation is performed. The arm (24) is interlocked and connected by the piece (26), and the rotary tiller ff(B) is raised at high speed. Then, when the operating lever (20) is operated to the lowering side (D), the arm (24) is moved by the spring (2) while the rotary tiller (B) is lowered to the set position near the ground.
5), and in the set position, the retaining bottle (30) of the arm (24) comes into contact with the end of the elongated hole member (31), and in the damper mechanism (39), the hydraulic oil (L ) passes through the orifice (32), the arm (24) operates slowly, and the rotary tiller (B) lands at a low speed.

In addition, the damper mechanism (39) is a switching lever (40).
(
It can be switched to the lowering side position (lowering side position), and by canceling the rotational speed suppression function, it is possible to move up and down at high speed over the entire lifting range in fields with light soil.

(Another Embodiment) ■ As shown in FIG. 9, a position adjustment screw mechanism (41) is installed at the portion of the elongated hole member (31) that abuts the engagement pin (30).
By providing this, the setting position at which low-speed descent starts can be arbitrarily adjusted, and even if the rotary tiller (B) is replaced with a rotary tiller (B) of a different diameter, the position where the rotary tiller (B) only touches the ground can be adjusted. Low speed conditions are possible.

■ In the hydraulic damper mechanism (39), the orifice (32) is provided in the external piping oil passage that communicates the oil chambers on both sides of the piston (28), and the diameter of this orifice is determined from the outside by a needle valve or the like. By configuring the damper to be adjustable, it is possible to adjust the damper performance and adjust the lowering speed at low speeds.

(2) As the damper mechanism (39), in addition to the hydraulic type, a pneumatic type or a mechanical friction type can also be used.

■ The present invention can also be implemented in the following forms.

That is, as shown in FIG.
) is freely rotatably attached to the support shaft (34) of the arm (
35) and the operating arm (14) of the operating shaft (13) of the position control valve (11) with the push/pull rod (3
6), and the operating shaft (13) is connected to the tension spring (2).
5), the valve (11) is operated in the downward direction by a tension spring (25), and is locked when the operation lever (20) is operated in the upward direction. The piece (37) is configured to abut and interlock with the arm (35), and when the operating shaft (13) is rotated from the set position to the downward side, the operating arm (14) engages the compression spring (3).
The damper mechanism (39) may be constructed so as to suppress the rotational speed by abutting against the damper mechanism (39) and biasing it in the opposite direction.

In this case, it is desirable to provide a suitable amount of frictional resistance to the valve operating shaft (13), and if this frictional resistance is adjustable, the low descending speed can be adjusted.

Incidentally, although reference numerals are written in the claims section for convenient comparison with the drawings, the present invention is not limited to the structure shown in the accompanying drawings.

[Brief explanation of the drawing]

The drawings show an embodiment of the lift arm drive device for an agricultural tractor according to the present invention, in which Fig. 1 is a partially cutaway side view of the main part, Fig. 2 is a longitudinal sectional front view of the main part, and Fig. 3 is a perspective view of the main part. Fig. 4 is a side view of the beam lift 1 and the connecting part, Fig. 5 is a sectional view taken along the line ■-V in Fig. 4, Fig. 6 is a side view of the lower link connecting part, and Fig. 7 is a side view of the connecting part in Fig. 6. ■-■ line sectional view, Figure 8 is a side view of the rear of the tractor, Figure 9 is a side view of the main part of an embodiment in which a part of the main embodiment is modified, and Figure 10 is a simplified side view of another embodiment. It is a diagram. (3)...Hydraulic cylinder, (11)...
・Position control pal 7', (13)...
... fH7 axis, (20) ...... operation lever, (2
5) Spring, (39) Damper mechanism.

Claims (1)

[Claims] A lift arm drive device for an agricultural tractor configured to control a hydraulic cylinder (3) for lifting and lowering a lift arm drive by a mechanical position control valve (11), wherein the position control valve (11)
The manual operation lever (20) for the valve (11)
The operating shaft (13) can be operated in advance only in the downward operating direction and can be held at any operating position, and the operating shaft (13) rotates following the operating lever (20). A damper mechanism (3) biases the operation shaft (13) in the downward operation direction with a spring (25) and suppresses the following rotational speed of the operation shaft (13) from the set position to the downward direction.
9) A lift arm drive device for an agricultural tractor equipped with.