JPS60112937A - Hydraulic controller for front loader - Google Patents

Abstract

PURPOSE:To maintain a working member in a horizontal state, by a method wherein a valve, which communicates rod oil for a cylinder for working to a bottom chamber when, with a control valve for boom brought to a neutral state, a control valve for operation is swung downward, is located between an oil passage running between the cylinder for working and the control valve for operation. CONSTITUTION:A boom cylinder 7 and a bucket cylinder 9 are connected in a tandem manner to a hydraulic pump 12. Pressure oil in a piping in the rod side is communicated with a switching valve 23 through a check valve 24 between a piping 20 on the bottom side and a piping 21 on the rod side of a bucket cylinder 9. A switching valve 23 detects control of a control lever 18 for boom and a control lever 19 for bucket and switches the bucket for operation so that the bucket can be early swung downward when a boom is inoperative and the bucket can be slowly rotated downward when the boom is operative. This enables raising of the boom in a condition that the bucket is maintained horizontally, and performs excellent and safe operation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to hydraulic control of a front loader, and it is possible to quickly rotate a working part such as a packet downward when the boom is not operated, and also to control the operation of the boom. Sometimes the aim is to be able to rotate the working part slowly.

A front loader is equipped with a boom cylinder that moves the boom up and down, and a packet cylinder that moves the packet up and down, including a hydraulic pump, a boom/cylinder control valve that controls the boom cylinder, and a packet cylinder that controls the packet cylinder. Some cylinder control valves are connected in series in the above order so that both cylinders can be operated simultaneously.

By the way, some conventional packet cylinder control valves are designed to supply return oil from one oil chamber of the packet cylinder to the other oil volume at the downward rotating operation position. , there is an advantage that the downward rotation speed of the packet is fast.

However, in the above-mentioned conventional device, when the packet was rotated downward, the rotation speed was fast regardless of whether the boom was operated or not, so when carrying out work such as removing earth and sand, loading work, etc. There was a problem in that it was extremely difficult or impossible to raise the boom while keeping it in a horizontal state, and the work could not be performed efficiently and safely.The present invention solves the above problem. Its features include a boom cylinder that swings the boom up and down;
A working part cylinder that is pivotally supported at the tip of the boom and moves the working part up and down, and both cylinders can be operated at the same time, and a pair of oil connecting the working part cylinder and the working part cylinder control valve. A supply oil passage is provided between the passages and supplies return oil from one oil chamber of the working section cylinder to the other oil chamber when the boom cylinder control valve is in the neutral position and the working section cylinder control valve is in the downward rotation operation position. It has the following features.

Hereinafter, one embodiment of the present invention will be described based on the drawings.
In the figure, 4) is a tractor, and a three-point link mechanism (2) is installed at the rear of the tractor, as well as a hydraulic system (3) for lifting and lowering a working machine.

(4) is a bucket-type front loader for mounting on a tractor, which includes a pair of left and right booms (6) that are pivotally supported on the mounting frame (5) of the tractor Ill, and a pair of right and left booms that swing the boom (6) up and down. Work exemplified with a cylinder (7) and a packet pivotally supported at the tip of the boom (6)dii i
81, and a pair of left and right working part cylinders (9) that move the working part ill up and down.

As shown in Figure 2, one or both mounting frames (5)
A lock pin (10) is freely inserted and removed between both side plates at the upper end, and is in contact with the lower surface of the base of the boom (6) to hold the boom (6) in the raised position shown by the solid line in Fig. 1. , seat of tractor [1] (boom 16 by operation from seat 1)
can be easily held in the raised position.

Figure 3 shows the hydraulic control circuit for the front loader (4), including the hydraulic pump (1 barrel) installed on the tractor (1), the boom cylinder control valve (0) that controls the boom cylinder (7), and the hydraulic control circuit for the front loader (4). The working part cylinder control valve H that controls the part cylinder (9) and the hydraulic system (3) are connected in series in the above order. θ5) is a loader side relief valve, which is supplied from the hydraulic pump θ. Limit the total pressure of the pressurized oil to within the specified pressure. +1flOQη is a check valve.

The boom cylinder control valve Q8) is a six-bottom, three-position manual switching valve having an operating lever (18), and is adapted to supply pressure oil to the working part cylinder control valve (14) at each operating position; Boom cylinder (7) and working cylinder (9)
simultaneous operations are possible.

The working part/linda control valve H has an operation lever 6,
The port is a 3-position manual valve and supplies pressure oil to the hydraulic system (8) in the neutral position.

Of the pair of first and second oil passages connecting the working part cylinder control valve α and the working part cylinder (9), the working part -
8) A throttle valve (2"4 is interposed in the second oil passage (2υ) through which the return oil from the working part cylinder (9) passes during downward rotation, and the throttle valve in the second oil passage @υ A supply oil passage (2) is interposed between a portion closer to the working part cylinder (9) than the valve slope and the first oil passage (c) on the other side.

In the supply oil passage, a check valve and a switching valve are installed in series in the above order from the first oil passage to the second oil passage Qυ.

The check valve t24j prevents oil from flowing from the first oil passage (A) toward the second oil passage (2υ) in the supply oil passage (C).

The 7 switching valve (c) is a 2-point, 2-position switching solenoid valve that has a closing operation position and an opening operation position. is operated to the open operating position.

Therefore, the following configuration is adopted to control the solenoid qη of the switching valve.

That is, the first limit switch is operated by the rotation V of the operating lever 4, and is in the OFF state 8 when the boom cylinder control valve is in the neutral position.
ON when the above control valve a is in the ascending and descending operating positions.
It becomes a status book.

→ is the second limit switch, which is activated by the rotation of the operating lever t191, and is operated when the working part cylinder control valve +141 is in the neutral position and in the upper rotation operating position.
The FF state is 8, and the control valve a< is in the downward rotational operation position and becomes ONN.

Figure 4 shows the discrimination circuit, with both limit switches (
This determines the state in which the solenoid of the switching valve (to) will be operated in the case of 4, and is equipped with a knot gate 4 and an ant gate 111ffi.

Then, the above-mentioned discrimination circuit selects the first limit switch (
Only when the second limit switch (c) is in the OFF state and the second limit switch (4) is in the ON state, the solenoid is actuated and the switching valve (-) becomes the open operating position.
) The return oil from the tip $11 oil amount to the second oil path υ side flows through the supply oil path (to) and the first oil path to the base side oil chamber of the working part cylinder (9). be supplied to

According to the embodiment configured as described above, each control valve 03)
(By operating l Shu, each cylinder +71 +9
1, the boom (6) and the working part i81 can be operated individually or simultaneously, and the hydraulic system (3) can be operated in the same manner as before.

That is, regardless of the operating position of the boom cylinder control valve 031, when the working part cylinder control valve θa is in the neutral position or the upward rotation operating position, the switching valve is in the closing operating position, As in the conventional case, the working part i8) can be rotated upward.

Furthermore, when the boom cylinder control valve (11) is in the neutral position, when the working part cylinder control valve (14) is moved to the downward rotation operation position, the switching valve - is the open operating position.

As a result, the oil in the oil chamber on the tip side of the working part cylinder (9) is pushed out as return oil to the second oil path υ side by the weight of the working part +81 and the weight of the work part 8) and the objects to be transported inside. , this pushed-out return oil is combined with the pressure oil in the first oil passage τ through the supply oil passage τ, and the working part cylinder (9
) is supplied to the base side oil chamber of the working part (8
) rotates downward at a fast speed.

Furthermore, when the boom cylinder control valves (1'4 are in the raising operation position or the lowering operation position), the working part cylinder control valves (α) can also be set in the downward rotation operation position, and the switching valves (2 and 9 are in the closing operation position). Therefore, the working part cylinder (9) is operated only by the pressure oil sent through the boom cylinder control valve θ and the working part cylinder control valve θ, so the working part +81 is moved downward. It rotates at a slow speed, so when scooping or loading earth and sand, etc., by simultaneously operating both control valves (+3) +14), it is easy to keep the working part i81 horizontal while boom (6) ), and the work can be done well and efficiently.

In the actual example, the switching valve and both control valves are electrically interlocked, but they may be mechanically interlocked. or,
The switching valve may not be interlocked with both control valves, but may be operated separately using an operating lever. Furthermore, both control valves may be connected in parallel to the hydraulic bonder, so that both cylinders can be operated simultaneously.

As described in detail above, according to the present invention, when the boom is not operated, the working part such as the back cut can be quickly rotated downward 110, and when the boom is operated, the working part can be rotated downward. Therefore, when scooping or loading earth and sand, the boom can be easily raised while keeping the work section horizontal, making the work better, safer and more efficient. can do well. The present invention has the above advantages and is an advantageous dog.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is an overall side view;
Figure 2 is a sectional view taken along line A-A in Figure 1, and Figure 3 is curve aE.
The Lgl road diagram, FIG. 4, is a discrimination circuit. (4)...Front loader, H61...Boom, t
7+...Boom cylinder, 18)...Working part, +
91...Working part cylinder, (1 fathom...Boom cylinder control valve, (14)...Working part cylinder control valve, (Foundation)...Check valve, (2f!...Switching valve.

Claims (1)

[Claims] 1. Equipped with a boom cylinder that swings the boom up and down, and a working section cylinder that moves the entire f' working section up and down, which is pivotally supported at the tip of the boom, making it possible to operate both cylinders at the same time. When the boom cylinder control valve is in the neutral position and the working cylinder control valve is in the downward rotation operation position, there is a gap between the pair of oil passages connecting the working cylinder and the working cylinder control valve. A hydraulic control device for a front loader, comprising a supply oil path for supplying return oil from one oil quantity to the other oil quantity.