JPH01317307A - Hydraulic control device for tractor - Google Patents

Abstract

PURPOSE:To reduce the processing cost and the machine weight by integrating a control valve and an operation lever table to a cylinder head fixed to the front part of a cylinder liner and forming a cylinder case with a soft material. CONSTITUTION:A cylinder head 3 is fixed to the front part of a cylinder case 1 and a cylinder liner 2 and is integrated with a control valve V and an operation lever table 7. A high-pressure oil line passes through only the cylinder head 3 made of cast iron, the control valve V and the cylinder liner 2. Accordingly, the cylinder case 1 can be produced by aluminum casting, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to the arrangement of a hydraulic control device for rotating a lift arm for raising and lowering a working machine mounted on a tractor.

(b) Prior Art Techniques related to hydraulic control devices for tractors have been known for a long time.

For example, it is disclosed in Japanese Utility Model Application Publication No. 59-29109 ta0.

(c) Problems to be Solved by the Invention However, in the prior art, the hydraulic case was made of cast iron, and a cylinder hole was formed in the hydraulic case itself 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 for that purpose is bored in the hydraulic case, and the position of the control valve is controlled.
A link mechanism was installed to control the draft.

However, in recent years, combined with the desire for simpler machining and lighter weight, when the hydraulic case part is made of aluminum casting, even if the cylinder hole is machined into the case, the strength is weak and it can withstand high pressure. Since it is not possible to do so, only the cylinder case is made of aluminum casting, and a cast iron cylinder liner 2 is inserted inside it.
The structure is designed to provide sufficient strength. However, when the cylinder case l is made of aluminum casting, the control valve, which has conventionally been fixed to the bottom of the hydraulic case, and the control lever device supported on the side are also made of aluminum, which has sufficient strength and durability. In particular, the mounting surface of the control valve and the part where the oil passage is drilled must be made of cast iron or cast iron.

In the present invention, a control valve (1) and an operating lever stand are integrally attached to a cylinder head 3 fixed to the front part of a cylinder liner 2.

(d) Means for Solving the Problems The objects of the present invention are as described above. Next, the structure for achieving the objects will be explained.

In the case where the cylinder head 3 is fixed to the front end of the cylinder case 1 into which the cylinder liner 2 is inserted, the front side of the cylinder head 3 has a pump port 36, a cylinder port 39, and a main cylinder that communicates with the transmission case through the cylinder case 1. The control valve 50 is opened so that the control valve 2 can be attached thereto, and the control lever stand 7 supporting the control lever and feedback arm connected to both ends of the control bar for operating the control valve V is attached to the control valve 50. It was equipped with.

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

FIG. 1 shows a hydraulic control system for a tractor according to the present invention.
A perspective view with the lid 4 and valve case 6 removed;
Figure 2 is a side cross-sectional view of the cylinder liner 2, cylinder head 3, and valve case 6, Figure 3 is a plan view showing the configuration of the operating lever, position control/depth control, and Figure 4 is a partial front view. location map,
Figure 5 is a 2 = 2 cross-sectional view taken from the arrow in Figure 2, Figure 6 is a Y-Y cross-sectional view from Figure 2, and Figure 7 is taken from the X-X line in Figure 5.
FIG.

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

An arm shaft (not shown) is pivotally supported at the rear of the cylinder case 1, and lift arms IIL and IIR are fixed to both ends of the arm shaft.

A cast iron or steel pipe type cylinder liner 2 is inserted into the inside of the cylinder case.

The throat 3 is fixed to the cylinder on the front surface of the cylinder case L and the cylinder liner 2.The rear protrusion 3a of the cylinder head 3 is tightly fitted to the front end of the cylinder liner 2, and the cylinder liner 2 and the cylinder head are tightly fitted. This improves the fixing strength of No. 3.

Further, long bolts B1 for fixing the cylinder head 3 are screwed into the flesh pressure portion of the cylinder case 1.

A pressure oil inlet hole 2 is provided on the left front side of the cylinder head 3 as shown in the figure.
9 is open, and pressure oil from a pressure oil pump mounted on the engine part of the tractor is fed to the pressure oil inlet hole 29 through a piping 17.

On the left side of the cylinder head 3, there is a pressure oil external extraction body 1 that sends and returns pressure oil to the valve ■3 of the external work machine.
6 is fixedly installed, and mounting screws for an overload relief valve (1), a main relief valve (V2), and a check valve (4) are screwed into the upper part of the cylinder head 3.

Further, a slow return stop valve 10 is screwed into the cylinder toward the right front of the throat 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 body 4 serves as a lid for the valve case 6 and as an oil passage plate.

In addition, a control valve (■) is arranged inside the valve housing chamber constituted by the lid body 4 and the valve case 6, and the control valve is attached to the cylinder head 3 with long bolts and bolts while the lid body 4 is held between the long bolts. It is fixed through hole B2.

Also, operate the lid body 4 and the top surface of the valve case 6/<-stand 7
, and place the position control lever 8 and the trough [-control lever 9,
A position control bar 15, a draft control bar 14, a position feed hack arm 12, a draft feedback arm 13, etc. are arranged T.

The configuration of the levers configured on the operating lever stand 7 will be explained with reference to FIGS. 2 and 3.

The base of the position control lever 8 is the lever shaft 18
An arm 22 is attached to the other end of the lever shaft 18.
is permanently installed. A position control bar 15 is pivotally supported on the arm 22, and an arm 23 of an arm shaft 26 is pivotally supported on the other end of the position control bar 15.

A position feed hack arm 12 is fixed to the right end of the arm shaft 26, and the position feed hack arm 12 is connected to the base of the lift arm and the links 11, 1.
It is linked with.

Also, the base of the draft control lever 9 is connected to the lever shaft 1.
An arm 21 is fixed to the left end of the lever shaft 19. A draft control bar 14 is pivotally connected to the tip of the arm 21, and an arm 24 at the left end of an arm shaft 27 is pivotally connected to the rear end of the draft control bar 14.

The draft feedback arm 13 is fixed to the right end of the arm shaft 27.

The draft feed hack arm 13 is linked to a portion of the driver 71-sensor of the work machine by a wire.

In addition, if the raft feedback arm 13 is connected to the depth sensor of the working machine, it can also be used as a depth control.

The lever shaft 18 is pivotally supported inside the lever shaft 19,
The lever shaft 19 is pivotally supported inside the pivot tube 20.

Further, the arm shaft 26 is pivotally supported inside an arm shaft 27, and the arm shaft 27 is pivotally supported inside a pivot tube 28.

Both kinds of support tubes 20 and 28 are fixedly installed on the operating lever stand 7.

In addition, the position control bar 15 and the draft control bar 1
4 is a retainer whose lower end is fixed to the upper end of the spool 5 of the control valve V, whose position is raised and lowered by the rotation of the two operating levers 8 and 9 and the two feed hack arms 12 and 13. It abuts on top of the pin 25.

In addition, the spool 5 is always urged upward by the urging spring inside the control valve ■, and the retaining pin 25 comes into contact with either the draft control bar 14 or the position control bar \-15, and its position It is configured so that it is determined.

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

Two li levers 8 and 9 and two fee F noz.
The two control bars 15 and 1 are controlled by the Tsuku arms 12 and 13.
4 moves up and down, and the functions of automatically controlling the raising, stopping, and lowering of the working machine are the same as those of the conventional technology, so the explanation will be omitted here.

Next, the flow of pressure oil flowing into the hydraulic system from the piping 17 will be explained using cross-sectional views of the cylinder head 3 shown in FIGS. 2, 3, and 4.

The piping 17 is screwed into a pressure oil inlet 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 inlet hole 29, and flows through the outlet 33 of the pressure oil external extraction body 16 attached to the side of the cylinder head 3.
Oil is sent to valve V3 attached to another work machine. The pressure oil that has been used to raise and lower the working machine returns to the return port 34 under the control of the valve V3. The return port 34 communicates with a pressure oil return hole 35 of the cylinder head 3, and passes from a pump port 36 whose end is open toward the front of the cylinder head 3 through an oil passage in the lid body 4 to the control valve V. It is sent to the pump port VP.

If there is no need to send pressure oil to the valve 3 of another working machine, replace the pressure oil external outlet 16 with a lid body provided with a U-shaped communication oil passage, and connect the discharge port 33 and The return port 34 is communicated with the return port 34.

The pressure oil sent from the pump port 36 to the control valve (V) is transferred to the spool 5 inside the control valve (V).
The controlled pressure oil is discharged from the cylinder port 39 of the control valve V to the oil passage 40 from the cylinder port 39 of the control valve V.

At the left end of the a & oil passage 40, there is provided an outlet 55 for taking out the pressure oil after being controlled by the control valve V 47u.

Further, in the middle of the oil passage 40, there is provided an oil passage 54 that leads to the slow return stop valve 10.The oil passage 54 is connected to the 1. It is connected to Aburabi 42.

Slow return and stop are performed by adjusting the opening area of the oil passage 54 by adjusting the degree of protrusion of the slow return/stop pulp 10.

The slow return stop pulp 1o is effective only when lowering the working machine, and a check valve V4 is provided so that it is not necessary to pass through this passage when raising the working machine. It is.

When the work equipment is raised, the check valve V4 opens against the biasing spring, so that the pressure oil in the oil passage 4° flows into the oil passage 54, which is throttled by the slow return stop pulp 1o.
The oil passage 53 passes through the check valve v4 without passing through the
The oil flows into the oil passage 42-1.

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

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

The drain oil passage 37 communicates with a tank port 51 that opens on the front surface of the cylinder head 3.

Further, as shown in FIG. 6, the main relief valve 2 disposed in the oil passage 58 communicating with the pressure oil inflow hole 29 also communicates with the drain oil passage 57, and the drain oil spouted from here also flows through the tank port 51. through the oil path inside the lid body 4,
It returns to the inside of the valve case 6.

The pressure oil discharged from the control valve ■ into the mata valve case 6 and the pressure oil discharged from the tank port 51 into the valve case 6 are passed through the main tank port 50 opened to the lid body 4 and the cylinder head 3. Then return to the mission case.

In addition, B3 shown in FIGS. 1 and 5 is a long bolt and a bolt hole that connect the valve case 6 and the lid body 4 and are aligned with the cylinder head 3.

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

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

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 and is combined with the drain oil from the overflow relief valve V1. They are collected at the tank port 51. The oil is then returned to the transmission case via the main tank port 50 which opens from the cylinder head 3 to the transmission case via the oil passage 37.

FIG. 1θ is a hydraulic circuit diagram of the present invention.

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

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

Second, since the control valve (2) is simply attached to the front of the cylinder head 3, the control valve (2) can be easily inspected and repaired by removing it.

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

[Brief explanation of the drawing]

FIG. 1 shows a hydraulic control system for a tractor according to the present invention.
A perspective view with the lid 4 and valve case 6 removed;
Figure 2 is a side cross-sectional view of the cylinder liner 2, cylinder head 3, and valve case 6, Figure 3 is a plan view showing the configuration of the operating lever, position control/depth control, and Figure 4 is a partial front view. cross section,
5 is a cross-sectional view taken along line 2-2 in FIG. 2, FIG. 6 is a cross-sectional view taken along line Y-Y in FIG. 2, and FIG. 8 and 9 are side sectional views and front sectional views of other embodiments, and FIG. 10 is a hydraulic circuit diagram of the present invention. l... Cylinder case 2... Cylinder liner 3... Cylinder head 4... Lid body 5... Spool 6... Valve case 7... Operation lever base 8... Position control lever 9 ...Traft control lever applicant Kanzaki Kokyukoki Seisakusho Co., Ltd. Agent Patent attorney Toshibe Yano Figure 7

Claims (1)

[Claims] Cylinder case 1 with cylinder liner 2 inserted
In the cylinder head 3 fixed to the front end of
On the front of the cylinder head 3, there is a pump port 36,
The cylinder port 39 and the main tank port 50 communicating with the transmission case through the cylinder case 1 are opened to allow the control valve V to be installed, and the control lever is connected to both ends of a control bar for operating the control valve V. A hydraulic control device for a tractor, characterized in that the control valve V is equipped with an operation lever stand 7 supporting a feedback arm.