JPH0763242B2 - Hydraulic control of tractor - Google Patents

Description

The present invention relates to an arrangement of a hydraulic control device for rotating a lift arm for raising and lowering a work machine mounted on a tractor.

(B) Conventional Technology Conventionally, the technology related to the hydraulic control device of the tractor has been known.

For example, it is as in Japanese Utility Model Laid-Open No. 59-29109.

(C) Problems to be Solved by the Invention However, in the conventional technology, the hydraulic case is made of cast iron, and the hydraulic case itself is formed with a cylinder hole by machining to form a hydraulic cylinder.

Then, a control valve is attached to the bottom of the hydraulic case, and a high-pressure oil passage therefor is bored in the hydraulic case while controlling the position of the control valve,
The link mechanism for draft control was installed.

However, coupled with the desire for simplification and weight reduction in recent years, when the hydraulic case part is made of aluminum casting, even if a cylinder hole is opened in this case by machining, its strength is weak and it can withstand high pressure. Therefore, only the cylinder case is made of aluminum casting, and the cast iron cylinder liner 2 is inserted into the cylinder case to obtain sufficient strength. However, when the cylinder case 1 is made of aluminum casting, the control valve that has been conventionally fixed to the bottom of the hydraulic case and the operation lever device supported on the side are also expected to have sufficient strength and durability with aluminum casting. In particular, the mounting surface of the control valve and the portion where the oil passage is bored must be formed of cast iron or casting.

In the present invention, the control valve V and the operation lever base are integrally attached to the cylinder head 3 fixed to the front portion of the cylinder liner 2.

(D) Means for Solving the Problems The object of the present invention is as described above, and a configuration for achieving the object will be described below.

A cylinder liner 2 made of cast iron or steel pipe is inserted into a cylinder case 1 made of aluminum casting, and a cylinder head 3 made of cast iron is fixed to the front end of the cylinder liner 2. The pump port 36, the cylinder port 39, and the member tank port 50 communicating with the mission case through the cylinder case 1 are opened, and a control valve V made of cast iron can be mounted and the control valve V is operated. The control bar V and a control lever connected to both ends of the control bar and an operation lever base 7 for supporting a feedback arm are attached to the control valve V.
It is attached to.

(E) Embodiment The object and structure of the present invention are as described above, and the structure of the embodiment shown in the accompanying drawings will be described below.

FIG. 1 shows a hydraulic control device for a tractor according to the present invention.
A perspective view of a state in which the lid 4 and the valve case 6 are removed.
FIG. 2 is a side sectional view of the cylinder liner 2, the cylinder head 3 and the valve case 6, FIG. 3 is a plan view showing the structure of the operating lever and the position control / depth control part, and FIG. 4 is the same front part. Cross section,
5 is a sectional view taken along the line ZZ of FIG. 2, FIG. 6 is a sectional view taken along the line YY of FIG. 2, and FIG. 7 is a sectional view taken along the line XX of FIG. .

The cylinder case 1 is mounted and fixed on the upper surface of a mission case which is also made of aluminum casting, or is made of aluminum casting integrally with the mission case.

An arm shaft (not shown) is pivotally supported at the rear of the cylinder case 1, and lift arms 11L and 11R are fixedly provided at both ends of the arm shaft.

Inside the cylinder case 1, a cylinder liner 2 made of cast iron or steel pipe is inserted.

The cylinder head 3 is fixedly attached to the front surfaces of the cylinder case 1 and the cylinder liner 2. The rear projection 3a of the cylinder head 3 is closely fitted to the front end of the cylinder liner 2 so that the cylinder liner 2 and the cylinder head 3 are attached. The fixing strength of is improved.

Further, a long bolt B1 for fixing the cylinder head 3 is screwed into the wall pressure portion of the cylinder case 1.

A pressure oil inflow hole 29 is provided on the left front surface of the cylinder head 3 in the figure.
Is opened, and pressure oil from a pressure oil pump mounted on the engine portion of the tractor is sent to the pressure oil inflow hole 29 by piping 17.

On the left side surface of the cylinder head 3, a pressure oil external take-out body 16 for sending / returning pressure oil to / from the valve V3 of the external working machine is fixed, and an over rod relief valve V1 is provided above the cylinder head 3. And main relief valve V2, check valve
V4 mounting screw is screwed.

Further, a slow return stop valve 10 is arranged by screwing toward the front right of the cylinder head 3.

A lid 4 is attached to the front surface of the cylinder head 3, and a valve case 6 is fixed to the lid 4. The lid 4 serves as a lid for the valve case 6 and as an oil passage plate.

Further, a control valve V is arranged inside a valve accommodating chamber formed by the lid body 4 and the valve case 6, and the control valve V holds the lid body 4 with long bolts, and the cylinder head 3 has long bolts and bolts. It is fixed at hole B2.

Further, the operation lever base 7 is fixed to the upper surfaces of the lid body 4 and the valve case 6, and the position control lever 8, the draft control lever 9, the position control bar 15, the draft control bar 14 and the position are fixed on the operation lever base 7. Feedback Arm 12 and Draft Feedback Arm
13 mag is arranged.

The structure of the lever formed on the operation lever base 7 will be described with reference to FIGS. 2 and 3.

The base of the position control lever 8 is fixed to the lever shaft 18, and the arm 22 is fixed to the other end of the lever shaft 18. A position control bar 15 is pivotally supported by the arm 22, and an arm 23 of an arm shaft 26 is pivotally supported at the other end of the position control bar 15.

A position feedback arm 12 is fixed to the right end of the arm shaft 26, and the position feedback arm 12 is linked with the base of the lift arm by a link 11a.

Also, the base of the draft control lever 9 is the lever shaft 19
An arm 21 is fixed to the left end of the lever shaft 19. The draft control bar 14 is pivotally connected to the tip of the arm 21, and the arm 24 at the left end of the arm shaft 27 is pivotally connected to the rear end of the draft control bar 14.

At the right end of the arm shaft 27 is a draft feedback arm.
13 are fixed.

The draft feedback arm 13 is linked to the draft sensor portion of the working machine by a wire.

If the draft feedback arm 13 is connected to the depth sensor of the working machine, it can be used as the depth control.

The lever shaft 18 is pivotally supported inside a lever shaft 19, and the lever shaft 19 is pivotally supported inside a pivot cylinder 20.

The arm shaft 26 is pivotally supported inside the arm shaft 27,
The arm shaft 27 is pivotally supported inside the pivot cylinder 28.

Both pivotal support cylinders 20 and 28 are fixedly mounted on the operation lever base 7.

Further, the position control bar 15 and the draft control bar 14 have two operation levers 8 and 9 and two feedback arms 1
By the rotation of 2, 13, the position is moved up and down, and the lower end thereof abuts on the engaging pin 25 fixedly mounted on the upper end of the spool 5 of the control valve V.

The spool 5 is constantly urged upward by an urging spring inside the control valve V.
The engaging pin 25 is in contact with either 14 or the position control bar 15, and the position is determined.

Further, the engagement pin 25 moves up and down within the elongated hole 7b of the engagement portion 7a protruding from the operation lever base 7 so that the spool 5 does not rotate and change its position.

2 control levers 8 and 9 and 2 feedback arms 12,
Since the two control bars 15 and 14 are moved up and down by 13 and the operation of automatically raising, stopping, and lowering the working machine is the same as that of the conventional technique, the description thereof is omitted here.

Next, the flow of pressure oil flowing from the piping 17 into the hydraulic system will be described with reference to the sectional views of the cylinder head 3 shown in FIGS. 2, 3, and 4.

The piping 17 is screwed into a pressure oil inflow hole 29 opened in the cylinder head 3.

Therefore, the pressure oil discharged from the hydraulic pump attached to the engine enters the pressure oil inflow hole 29, and the discharge port 33 of the pressure oil external take-out body 16 attached to the side portion of the cylinder head 3 causes another working machine. The oil is sent to a valve V3 attached to the valve V3 and is controlled by the valve V3 to be used for raising and lowering the working machine. The return port 34 communicates with a pressure oil return hole 35 of the cylinder head 3, and an end of the return port 34 is opened from the pump port 36 opening toward the front surface of the cylinder head 3 through an oil passage in the lid body 4 to control valve V. It is sent to the pump port VP of.

When it is not necessary to send pressure oil to the valve V3 of another working machine, the pressure oil external extraction body 16 is replaced with a lid provided with a U-shaped communication oil passage, and the discharge port 33 and the return port are returned. It communicates with mouth 34.

The pressure oil sent from the pump port 36 to the control valve V is controlled according to the vertical movement of the spool 5 inside the control valve V, and the pressure oil after the control is supplied from the cylinder port VC of the control valve V to the cylinder port 39. It is discharged to the oil passage 40.

At the left end of the oil passage 40, an outlet 55 for taking out the pressure oil after being controlled by the control valve V is provided.

In the middle of the oil passage 40, an oil passage 54 communicating with the slow return / stop valve 10 is provided.
It communicates with the oil passage 42 via a short horizontal oil passage 52 as shown in the figure.

Set the opening area of the oil passage 54 to a slow return stop valve.
The slow return and stop are adjusted by adjusting the protrusion of 10.

The slow return stop valve 10 is effective only when the working machine is lowered, and when the working machine is raised, the check valve V4 is provided so as not to pass through this passage. is there.

When the work machine is raised, the check valve V4 opens against the biasing spring, so the pressure oil in the oil passage 40 does not pass through the oil passage 54 throttled by the slow return stop valve 10. The oil flows from the oil passage 53 into the oil passage 42 through the check valve V4.

The oil passage 42 communicates with the oil passage 41 opened in the cylinder and the overload relief valve V1, and sends the pressure oil into the cylinder liner 2.

If the pressure oil in the cylinder rises abnormally, the overload relief valve V1 opens and allows the pressure oil to escape to the drain oil passage 37.

Further, the drain oil passage 37 communicates with a tank port 51 which is open on the front surface of the cylinder head 3.

Further, as shown in FIG. 6, the main relief valve V2 arranged in the oil passage 58 communicating with the pressure oil inflow hole 29 is also communicated with the drain oil passage 57, and the drain oil ejected from the main relief valve V2 is also discharged by the tank port 51. It returns to the inside of the valve case 6 through the oil passage in the lid body 4.

Further, the pressure oil discharged from the control valve V inside the valve case 6 and the valve case 6 from the tank port 51.
The pressure oil discharged inside returns to the mission case via the lid 4 and the main tank port 50 opened in the cylinder head 3.

B3 shown in FIGS. 1 and 5 is a long bolt and a bolt hole which are fastened together with the valve case 6, the lid 4 and the cylinder head 3.

8 and 9 are a side sectional view and a front sectional view of another embodiment.

In this embodiment, the lid 4 is not interposed, and the control valve V is attached to the front surface of the cylinder head 3.
An upper valve case 60 and a lower valve case 61 are attached above and below the control valve V.

In this case, the drain oil from the control valve V is collected from the tank port VT to the tank port 51, and the drain oil from the main relief valve V2 passes through the drain oil passage 57 to the drain oil from the overload relief valve V1. Collected and collected in tank port 51. Then, it is returned from the oil passage 37 to the mission case via the main tank port 50 that opens from the cylinder head 3 to the Michelin case.

FIG. 10 is a hydraulic circuit diagram of the present invention.

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

First, since the high-pressure oil passage only passes through the cylinder head 3 made of cast iron, the control valve V, and the cylinder liner 2 made of cast iron or steel pipe, the cylinder case 1 may be made of a soft material, and is made of aluminum casting. Therefore, the processing cost can be reduced and the weight can be reduced.

Secondly, since the control valve V is merely attached to the front surface of the cylinder head 3, the control valve V can be easily inspected and repaired by removing the control valve V.

Thirdly, the operating lever base 7 is also attached to the control valve V and is exposed so that it is easy to replace, and it is easy to change the specifications such as only position control, with draft control, or only draft control. It can be done.

[Brief description of drawings]

FIG. 1 shows a hydraulic control device for a tractor according to the present invention.
A perspective view of a state in which the lid 4 and the valve case 6 are removed.
FIG. 2 is a side sectional view of the cylinder liner 2, the cylinder head 3 and the valve case 6, FIG. 3 is a plan view showing the structure of the operating lever and the position control / depth control part, and FIG. 4 is the same front part. Cross section,
5 is a view taken along the line ZZ of FIG. 2, FIG. 6 is a view taken along the line YY of FIG. 2, and FIG. 7 is a view taken along the line XX of FIG. 8 and 9 are a side sectional view and a front sectional view of another embodiment, and FIG. 10 is a hydraulic circuit diagram of the present invention. 1 …… Cylinder case 2 …… Cylinder liner 3 …… Cylinder head 4 …… Cover 5 …… Spool 6 …… Valve case 7 …… Operating lever base 8 …… Position control lever 9 …… Draft control lever

Claims (1)

[Claims] 1. A cylinder liner 2 made of cast iron or steel pipe.
Is inserted into a cylinder case 1 made of cast aluminum, and a cylinder head 3 made of cast iron is fixed to the front end of the cylinder liner 2. A pump port 36 and a cylinder port 39 are provided in front of the cylinder head 3. And a main tank port 50 communicating with the transmission case through the cylinder case 1 is opened, and a cast iron control valve V can be mounted, and
A hydraulic control device for a tractor, characterized in that a control bar for operating the control valve V and an operation lever base 7 for supporting a control lever and a feedback arm connected to both ends of the control bar are mounted on the control valve V. .