JPH1082368A - Hydraulic device for loader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic system of a loader improving efficiency of equipment by applying a main pump and a pilot pump concerning the hydraulic system of the loader and especially being representative examples of construction machineries to a variable displacement hydraulic pump so that oil delivery varies in accordance with a loading state of the equipment. SOLUTION: This hydraulic system for a loader is furnished with a swash plate type main pump 1 to drive a working system and a steering system and a swash plate type pilot pump 2 to supply working oil to an operating lever to supply a pilot signal to a control valve part of the aforementioned working system. In this case, a regulator 9 to respectively change the swash plate inclinations of the aforementioned main pump 1 and the pilot pump 2 by change of pressure of a branch oil passage as well as respectively set in a first branch oil passage branched from a first supply oil passage 1A to which working oil is discharged from each of the aforementioned pumps is furnished.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic device for a loader, and in particular, a discharge oil amount varies depending on a load state of a swash plate type main pump and a swash plate type pilot pump of a loader, which is a typical example of a construction machine. The present invention relates to a hydraulic device for a loader in which the efficiency of equipment is improved by performing a function as a variable displacement type hydraulic pump.

[0002]

2. Description of the Related Art In general, a loader has mainly carried out a lifting operation of pumping a load such as earth and sand into a bucket and loading the load on a dump truck. Such a loader drives a working device and a steering device in which a main pump and a steering pump operated by the power of an engine are each composed of a boom and a bucket. The configuration of the loader will be described in detail with reference to FIG. 3, which is an attached drawing. The main pump (2) and the steering pump (3) driven by the engine, for example, a lift cylinder and a dump cylinder driven by the main pump (2) Working system actuators (17, 18), a number of control valves (14, 16) installed on hydraulic lines for driving the working device actuators and switching hydraulic oil discharged from the main pump (2); Pilot signals from a steering cylinder (10) driven by a steering pump (3) to steer equipment, a steering spool (6) operated by an operator's operation of steered wheels (not shown), and a hydraulic line of a steering device operator. The work equipment system hydraulic line is And equipped with a spool requests to determine the amount of hydraulic oil supplied to the hydraulic line of the steering device engaging (5).

Reference numeral 1 denotes a hydraulic tank, 4 denotes a check valve installed in an oil passage connecting a hydraulic line of a working device and a hydraulic line of a steering device, and 7 denotes a relief valve of the steering device. , 11 is a relief valve for working equipment
Reference numeral 8 denotes a steering device suction valve, and reference numeral 12 denotes a working device suction valve.

[0004] When the equipment is operated and the engine is driven in such a state, the main pump (2) is connected to the oil passage (2).
Hydraulic oil discharged via A) is switched by the control valves (14, 16) to the actuator (1).
7, 18), and the operating oil discharged from the steering pump (3) through the oil passage (3A) operated the steering cylinder (10) by switching the steering spool (6).

On the other hand, when the equipment is operated with no load,
That is, when the steering device and the working device are not driven, the spool of each control valve is located at its neutral position as shown. by this,
The hydraulic oil discharged from the steering pump (3) and the main pump (3) was returned to the tank (1) via all control valves.

[0006]

However, for the main pump and the steering pump of such a loader, a constant displacement type pump whose swash plate inclination angle is not changed is used. Therefore, when the equipment is in no-load operation, the pump always discharges a constant amount of oil set by the inclination angle of the swash plate, so not only the driving force of the bomb is wasted, but also a constant amount of oil is supplied to each control valve. There is a problem that the vehicle passes the control valve, thereby reducing the durability of the control valve and shortening the life of the equipment.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a hydraulic apparatus for a loader which reduces the amount of oil discharged from a hydraulic pump when the equipment is not loaded, saves the driving force of the engine, and increases the efficiency of the equipment. It is in.

Another object of the present invention is to provide a hydraulic apparatus for a loader which can maintain a constant pressure in a hydraulic oil supply oil passage even when the equipment is not loaded, thereby improving the response performance of the equipment. It is in.

Another object of the present invention is to reduce the driving force of the pump by allowing the hydraulic pump to operate with no load by communicating the discharge oil amount with the bypass oil passage when the equipment is not loaded,
It is an object of the present invention to provide a loader hydraulic device capable of preventing the heating of the device and extending the life of the pump, and preventing a rise in oil temperature and reducing the performance degradation and damage of the working device.

An object of the present invention is to provide a swash plate type main pump for driving a working system and a steering system, and a swash plate type for supplying hydraulic oil to an operation lever for supplying a pilot signal to a control valve section of the working device meter. In a hydraulic device of a loader provided with a pilot pump, a change in pressure of the branch oil passage is provided in each of a first branch oil passage branched from a first supply oil passage from which hydraulic oil is discharged from the name pump. And a regulator for switching the inclination angle of the swash plate of the main pump and the pilot pump.

[0011]

According to a preferred aspect of the present invention, each of the regulators is installed in its own cylinder chamber so as to be capable of reciprocating swinging, and One end of the piston is installed in the cylinder chamber such that the piston connected to the swash plate of the pump reciprocates and reciprocally oscillates. A servo cylinder having an elastic member to be branched, a second branch oil passage branched from the first branch oil passage and communicated with the small chamber side of the servo cylinder, and a radial chamber of the servo cylinder branched from the first branch oil passage A third branch oil passage communicated with the second branch oil passage, the second branch oil passage being extended from the first branch oil passage so as to limit an amount of passing oil toward the third branch oil passage. An orifice installed in a connection oil passage connecting the third branch oil passage, and an orifice connected to the third branch oil passage and installed on an oil passage connected to the drain oil passage; It is provided with a proportional valve which receives the input of the operating pressure of the branch oil passage as a switching signal and is switched in proportion to the difference between the elastic pressure of its own elastic member and the operating pressure to drain the third branch oil passage. .

According to a preferred feature 2 of the present invention, the elastic member of the proportional valve is a variable elastic member capable of changing a set elastic pressure by an operator.

According to a preferred feature 3 of the present invention, the accumulator is provided on the first supply oil passage of the pump to compress the hydraulic oil discharged from the pump, and the hydraulic oil compressed by the accumulator is Check valves are also provided in the supply oil passages between the pumps and the accumulator to prevent backflow to the pumps.

According to a preferred feature 4 of the present invention, the pump is connected to the first supply oil passage between the check valve installed in the first supply oil passage and the pump and communicates with the air drain oil passage. An oil passage opening / closing pulp is provided in each of the oil passages and switches from an initial state in which the internal oil passage is closed to an open state in response to a predetermined signal.

According to a preferred feature 5 of the present invention, a main pump for driving a work system and a steering system, and a pilot pump for supplying hydraulic oil to an operation lever for supplying a pilot signal to a control valve section of the work system. In the hydraulic device of a loader provided with, each is installed in a first branch oil passage branched from an l supply oil passage from which hydraulic oil is discharged from the name pump, and the change in the speed of the branch oil passage causes the change in the speed. A regulator for switching the inclination angle of the swash plate of the main pump and the pilot pump, an accumulator installed on a first supply oil passage of the pump for reducing hydraulic oil discharged from the pump, and an accumulator for reducing pressure by the accumulator. In order to prevent the pressurized hydraulic oil from flowing back to the pump, each pump and the accumulator A check valve installed in a supply oil passage between the pump and a drain oil passage connected to the first supply oil passage between the check valve and the pump installed in the first supply oil passage; And an oil passage opening / closing valve for switching from an initial state in which the internal oil passage is closed to a state in which the internal oil passage is opened according to a predetermined signal.

[0016]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 and 2 show a hydraulic circuit diagram of a loader according to an embodiment of the present invention. As shown in the figure, the hydraulic system of the loader includes a working system driven by hydraulic oil discharged from a main pump (1) driven by an engine via a first supply oil passage (1A) and a traveling system. You. The traveling system operates in response to a signal from the operator's steered wheels (not shown) to supply the first oil supply passage (1
A) A steering system (3) for switching the hydraulic oil supplied via a steering system (3) and a set of steering cylinders (11, 1) for steering the equipment as driven by the hydraulic oil supplied by the steering system (3).
2) and a cushion (13) for preventing impact on equipment during steering.

On the other hand, the working system uses the pilot signals (a, b, c, d, f, g, h) to control the oil passage (IA).
Control valve (4) for switching the hydraulic oil supplied through the valve, this control valve (4)
Dump silicide (1
4), a lift cylinder (16, 17), and a relief valve (15) that determines the operating pressure of the hydraulic circuit by preventing the hydraulic line from rising above a predetermined pressure.

An operation lever installed in the second supply oil passage (2A) discharged from the pilot pump (2) for supplying a pilot signal to the main control valve (4) in proportion to an operator's signal. A section (5) and a pilot signal supply section (19) for controlling hydraulic oil supplied to the operation lever section (5) are provided.

Reference numeral 18 denotes an emergency steering system, 20 is a cooler for cooling the return oil, 21 is a hydraulic tank, and 22 is an air breather.
her).

The hydraulic device of the loader according to the present embodiment has a first
A regulator (9) that varies the inclination angle of the swash plate of the main pump (1) in order to change the amount of oil discharged from the main pump (1) in response to the feedback of the pressure in the oil passage (1A).
And operation of the first oil passage (1A) installed in the first oil passage (IA) to reduce excess hydraulic oil discharged from the main pump (l) to operate the traveling system and the work system. An accumulator (7) for maintaining the pressure at or above a predetermined pressure; and a check valve (6) for preventing pressure oil compressed from the accumulator (7) toward the main bomb (l) from flowing back. Be composed.

In the aforementioned regulation (9), while the equipment is working or running, the inclination angle of the swash plate of the main pump (l) is adjusted by receiving the feedback of the pressure of the l-th supply oil passage (1A). The main pump (l) is driven so that the discharge oil amount is maximized. Conversely, when the equipment is in a no-load state, the main pump (l) is driven so that the swash plate inclination angle of the main pump (l) is reduced and the discharge oil amount is minimized. For such an operation, the regulator (9) includes a second branch oil passage (90A) and a third branch oil passage (90A) respectively connected to the first branch oil passage (9A) communicated with the first supply oil passage (IA). A servo cylinder (90) having its own small chamber (91) and large chamber (92) connected to one end of each of the branch oil passages (90B);
An orifice (96) extended from the first branch oil passage (9A) and installed in a connection oil passage (90C) connecting the second branch oil passage (90A) and the third branch oil passage (90B); A proportional valve (3) that opens the third oil passage (90B) to the drain oil passage (21A) by the difference between the elastic pressure of the second elastic member (98) itself and the oil pressure acting on the second branch oil passage (90A). 97) and the servo cylinder (9)
0) is a piston (93) positioned to reciprocate and oscillate within itself, and one side of a main pump (1) swash plate to change the inclination angle of the swash plate as the piston (93) moves. A piston load (94) connected to the
A first elastic member (95) is provided in the large chamber (92) of the servo cylinder so as to elastically bias the piston (93) to the right end of the cylinder.

The second elastic member (9) of the aforementioned proportional valve
Reference numeral 8) denotes a variable elastic member capable of changing the set elastic pressure by the operation of the operator.

[0024] Further, it is set in (8A) of a fourth branch oil passage branched from the first supply oil passage (1A) and connected to the drain oil passage (21A), and is set by a valve spring by a predetermined signal. An oil passage opening / closing pulp (8) for switching an initial state of an oil passage closed state to a state of opening an oil passage is provided.

On the other hand, the configuration of the regulator (27) for varying the inclination angle of the swash plate of the pilot pump is the same as the configuration of the regulator (9) described above, so that the detailed description is omitted.

Hereinafter, the operation and effect of the embodiment constructed as described above will be described.

First, when the equipment is operated with all the control valves of the equipment in a neutral state (no load state), the hydraulic fluid (l) is discharged by the hydraulic oil discharged from the main pump (l).
The pressure of A) rises to the set pressure of the relief valve (15). That is, the third supply oil passage (3A) to the steering system and the fourth supply oil passage (4A) to the work system are in a closed circuit state, and the oil passage opening / closing valve (8) is in a position to close the oil passage. In the switched state, the pressure in the oil passage (1A) by the hydraulic oil discharged from the main pump (1) rises to the set pressure of the relief valve (15). At this time, the accumulator (7) compresses the hydraulic oil, and the regulator (9) is operated so that the swash plate inclination angle of the main pump (l) is reduced to minimize the discharge oil amount. This will be described in detail. One side of the piston (93) is generated by hydraulic pressure supplied into the small chamber (91) of the cylinder via the first branch oil passage (9A) and the second branch oil passage (90A). The acting force passes through the orifice (96) and the third branch oil passage (90B) and is supplied to the large chamber (92) of the cylinder by the oil pressure and the first elastic member (9).
The elastic force of 5) overcomes the force acting on the other side of the piston. As a result, the piston (93) moves to the left on the drawing. At this time, the proportional valve (97)
The pilot pressure due to the oil pressure acting on the branch oil passage (90A) overcomes the elastic force of the second elastic member (98) to switch the third branch oil passage (90B) to communicate with the drain oil passage (21A). Will be. Eventually, the proportional valve (97) returns the hydraulic oil in the large chamber (92) to the drain oil passage (21A) in proportion to the amount of movement of the piston (93). If the elastic force of the elastic member (98) is changed in such a state, the moving amount and moving speed of the piston (93) can be changed.

When the oil passage opening / closing valve (8) is opened in such a state, the fourth branch oil passage (8A) and the drain oil passage (21A) are connected. Therefore, the hydraulic oil of the main pump (1) is returned to the tank (21) without passing through the hydraulic lines of the working system and the steering system, and
The supply oil passage (1A) maintains the operating pressure at which the equipment can be driven by the accumulator (7).

On the other hand, when the work system, the steering system and the respective systems are simultaneously operated in such a state, the pressurized oil compressed by the accumulator (7) is supplied first. At the same time, the oil passage opening / closing valve (8) is switched to the oil passage closed state, and the hydraulic oil discharged from the main pump (l) is supplied to the respective systems. In this case, the swash plate inclination angle of the main pump (1) increases, and the discharge amount of the main pump (1) increases. That is, as the pilot signal pressure applied to the proportional valve (97) by the second branch oil passage (90A) decreases, the drain port of the proportional valve (97) is shut off to reduce the pressure in the third branch oil passage (B). When it is raised, the hydraulic pressure acting on the small chamber (91) of the cylinder at the same time decreases, and the piston (93) is moved to the right side in the drawing by the first elastic member, and the swash plate inclination angle of the main pump (1) is increased. Is to increase.

[0030]

As described above, the loader hydraulic device according to the present invention reduces the amount of oil discharged from the hydraulic pump when the equipment is not loaded, saves the driving force of the engine, and increases the efficiency of the equipment. Let it. In addition, the response performance of the equipment is improved by maintaining a constant pressure in the hydraulic oil supply oil passage, and the hydraulic pump can be operated with no load by communicating the discharge oil amount with the bypass oil passage when the equipment is not loaded Thus, the driving force of the pump is saved. As a result, there is an effect that the heating of the device is prevented, the life of the pump is extended, and an increase in the oil temperature is prevented, thereby lowering the performance of the working device and reducing damage.

[0031]

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram showing a hydraulic device of a loader according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a hydraulic circuit diagram showing a conventional hydraulic device of a loader.

[Explanation of symbols]

 Reference Signs List 1 main pump 1A first supply oil passage 2A second supply oil passage 2 pilot pump 3 steering system 4 main control valve 5 operation lever unit 6 check valve 7 accumulator 9 regulator 11 and 12 steering cylinder 13 cushion 14 dump cylinder 15 relief valve 16 , 17 Lift cylinder 18 Emergency steering system 19 Pilot signal supply unit 20 Cooler 21 Hydraulic tank 22 Air breather

Claims (8)

[Claims] 1. A swash plate type main pump for driving a working system and a steering system, and a swash plate type pilot pump for supplying hydraulic oil to an operation lever for supplying a pilot signal to a control pulp section of the working device. In the hydraulic device of the loader, each of the main pump and the main pump is provided in a first branch oil passage branched from a first supply oil passage from which the hydraulic oil is discharged from each of the pumps. A loader hydraulic device comprising a regulator for switching a swash plate inclination angle of a pilot pump. 2. Each of the regulators is installed in its own cylinder chamber so as to be capable of reciprocating vibration, and one end of the regulator is installed in a cylinder chamber such that reciprocating vibration of a piston connected to a swash plate of the pump is possible. A servo cylinder having an elastic member installed in its own large chamber and elastically biasing the piston toward its own small chamber, and a small cylinder side of the sabo cylinder branched from the first branch oil passage. A second branch oil passage that communicates with the first branch oil passage, a third branch oil passage that branches from the first branch oil passage and communicates with the large chamber side of the servo cylinder, and restricts an amount of passing oil toward the third branch oil passage. And an orifice extending from the first branch oil passage and installed in a connection oil passage connecting the second branch oil passage and the third branch oil passage, and the third orifice; It is located on the oil passage connected to the branch active passage and communicated with the drain oil passage, receives the operating pressure of the second branch oil passage as a switching signal, and in proportion to the difference between the elastic pressure of its own elastic member and the operating pressure. The hydraulic device for a loader according to claim 1, further comprising a proportional pulp for draining a third branch oil passage to be switched. 3. The loader hydraulic device according to claim 2, wherein the elastic member of the proportional pulp is a variable elastic member capable of changing a set elastic pressure by an operator. 4. An accumulator provided on a first supply oil passage of the pump for compressing hydraulic oil discharged from the pump, and preventing the hydraulic oil compressed by the accumulator from flowing back to the pump. 2. The hydraulic device for a loader according to claim 1, wherein check valves are provided in supply oil passages between the pumps and the accumulator. 5. An oil passage connected to the first supply oil passage between the check valve installed in the first supply oil passage and the pump and connected to the drain oil passage, wherein each of the oil passages is provided. The hydraulic device for a loader according to claim 1, further comprising an oil passage opening / closing valve for switching an initial state of closing an internal curved path to an open state by a predetermined signal. 6. A hydraulic device for a loader, comprising: a main pump for driving a work system and a steering system; and a pilot pump for supplying hydraulic oil to an operation lever for supplying a pilot signal to a control valve of the work system. , The swash plate of the main pump and the pilot pump is provided in a first branch oil passage branched from a first supply oil passage from which hydraulic oil is discharged from each of the pumps, and a change in pressure of the branch oil passage. A regulator for switching the inclination angle, an accumulator for reducing the pressure of hydraulic oil discharged from the pump, and a hydraulic oil compressed by the accumulator flows back to the pump. Installed in the supply oil passage between each of the pumps and the accumulator to prevent Check valve and the l-th
A check valve installed in the supply oil passage and an oil passage connected to the first supply oil passage between the pump and the drain oil passage and connected to the drain oil passage. A hydraulic device for a loader, comprising: an oil passage opening / closing valve that switches an initial state of closing a path to a state of opening. 7. Each of the regulators is installed in the cylinder chamber so as to be capable of reciprocating perturbation, and one end of each of the regulators is installed therein such that reciprocating perturbation of a piston connected to a swash plate of the pump is possible. A servo cylinder having an elastic member installed in its own large chamber and elastically biasing the piston toward its own small chamber side;
A second branch oil passage branched from the first branch oil passage and communicated with the small chamber side of the servo cylinder;
A third branch oil passage branched from the branch oil passage and communicated with the large chamber side of the servo cylinder, and extended from the first branch oil passage so as to limit an amount of passing oil toward the third branch oil passage; An orifice installed in a connection oil passage connecting the second branch oil passage and the third branch oil passage, and
It is installed on an oil passage connected to the branch oil passage and communicated with the drain oil passage, receives the operating pressure of the second branch oil passage as a switching signal, and determines the difference between the elastic pressure of its own elastic member and the operating pressure. The hydraulic device for a loader according to claim 6, further comprising a proportional valve that is switched in proportion to drain the third branch oil passage. 8. The hydraulic device for a loader according to claim 7, wherein the elastic member of the proportional pulp is a variable elastic member capable of changing an elastic pressure set by an operator.