KR100205568B1 - Hydraulic device of loader - Google Patents

Abstract

The present invention relates to a hydraulic device of the loader, and in particular, the main pump and the pilot pump of the loader, a representative example of a construction machine, by applying a variable capacity hydraulic pump so that the discharge flow rate can be changed according to the load condition of the equipment to improve the efficiency of the equipment It relates to an improved hydraulic device of the loader. The hydraulic device of the loader according to the present invention includes 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. In the hydraulic device of the loader, it is provided with a regulator which is provided in each branch passage branched from the supply passage from which the hydraulic oil is discharged from each of the pumps and switches the swash plate tilt angle of the pump in accordance with the change in the pressure of the branch passage.

Description

Loader hydraulics

The present invention relates to a hydraulic device of the loader, and in particular, the main pump and the pilot pump of the loader, a representative example of a construction machine, by applying a variable capacity hydraulic pump so that the discharge flow rate can be changed according to the load condition of the equipment to improve the efficiency of the equipment It relates to an improved hydraulic device of the loader.

In general, the loader has mainly performed the loading operation to load the load, such as earth and sand into the bucket and load it on the dump truck. Such a loader drives a work device and a steering device, each of which a main pump and a steering pump, which are driven by engine power, each consisting of a boom and a bucket. Referring to the configuration of the loader in detail with reference to Figure 2, the main pump (2) and the steering pump (3) driven by the engine, a lift cylinder that is a work system actuator driven by the main pump (2) 17) and the dump cylinder 18, a plurality of control valves (14, 16), steering pump (3), respectively installed in the hydraulic line for driving the work machine actuator, to switch the hydraulic oil discharged from the main pump (2) Driven by the steering cylinder 10 to steer the equipment, the steering spool 6 to operate according to the operator's steering wheel (not shown), and the pilot signal from the steering system hydraulic line is switched A demand spool 5 for determining the working flow rate supplied to the work system hydraulic line and the steering system hydraulic line was provided.

Reference numeral 1 is a hydraulic tank, 4 is a check valve installed in the flow path connecting the hydraulic system of the work system and the steering system, 7 is a relief valve of the steering system, 11 is a relief valve of the work system, 8 is a steering system suction valve, and 12 is a work system suction valve.

In this state, when the equipment is operated and the engine is driven, the hydraulic fluid discharged from the main pump 2 through the flow path 2A is operated by the switching of the control valves 14 and 16 and the actuators 17 and 18 are operated. , The operating cylinder discharged from the steering pump 3 through the flow passage 3A is operated by the switching of the steering spool 6 to operate the steering cylinder 10.

On the other hand, when the equipment is under no load operation, that is, when the steering system and the work system are not driven, the hydraulic oil discharged from the steering pump 3 and the main pump 3 drives all of the work system and the steering system actuators. Passed through the control valve and returned to tank (1). However, such a loader's main pump and steering pump use a fixed capacity pump which does not change the swash plate tilt angle of the pump, so that the pump always maintains a constant flow rate set by the tilt angle of the swash plate. Not only was the driving force of the pump wasted by discharging, but a certain flow rate was passed through each control valve, which lowered the durability of the control valve and shortened the life of the equipment.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydraulic apparatus for a loader which reduces the flow rate discharged from the hydraulic pump at no load of the equipment, saves the driving force of the engine and increases the efficiency of the equipment.

It is another object of the present invention to provide a hydraulic apparatus of a loader which can improve the reaction force of the equipment by maintaining a constant pressure in the hydraulic oil supply flow path even when the equipment is not loaded.

Still another object of the present invention is to communicate the discharge flow rate at no load of the equipment with the bypass flow passage so that the hydraulic pump can be operated at no load, thereby saving the driving force of the pump and preventing the heating of the device to extend the pump life. An object of the present invention is to provide a hydraulic device of a loader that can prevent a rise in oil temperature and thereby reduce performance degradation and damage of a work device.

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

Figure 1b is an enlarged view of the main part of Figure 1a,

2 is a hydraulic circuit diagram showing a conventional hydraulic device of the loader.

* Explanation of symbols used in the main part of the drawing

1: main pump 2: pilot pump

3: steering system 4: main control valve

5: operation lever 6: check valve

7: Accumulator 8: Flow opening / closing valve

9, 10: regulator 11, 12: steering cylinder

13: cushion 14: dump cylinder

16, 17: lift cylinder 15: relief valve

18: emergency steering device 19: pilot signal supply unit

20: cooler 21: tank

22: air breather 90: cylinder

91, 92: chamber 93: piston

94: piston rod 95: elastic member

96: orifice 97: proportional valve

An object of the present invention described above is a loader having 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 portion of the work system. In the hydraulic device, characterized in that it is provided with a regulator which is installed in each of the branch flow passage branched from the supply flow passage from which the hydraulic fluid is discharged from the respective pumps to switch the swash plate tilt angle of the pump in accordance with the change in the pressure of the branch flow passage By providing the hydraulics of the loader.

According to a preferred feature 1 of the present invention, each of the regulators may include a servo cylinder provided on one side of the pump, a first flow path branching the branch flow path and communicating with a large chamber side of the servo cylinder, and the branch flow path. And a second flow passage communicating with the small chamber side of the servo cylinder, and reciprocating in the cylinder chamber, and having one end connected to the swash plate of the pump, and installed in the small chamber, An elastic member elastically biased toward the large chamber side, an orifice provided in a connection flow path where the first flow path and the second flow path are connected, and an orifice for limiting the flow rate toward the second flow path, and branching the second flow path to communicate with the drain flow path. It is installed on the flow path to receive the operating pressure of the first flow path as a switching signal in proportion to the magnitude difference with the elastic pressure of its own elastic member And a proportional valve for draining the second flow path as it is switched.

According to a preferred feature 2 of the present invention, the elastic member of the proportional valve is a variable elastic member, the set elastic pressure can be changed by the operator.

According to a preferred feature 3 of the present invention, an accumulator for accumulating the hydraulic oil discharged from the pump, respectively, installed on the supply flow path of the pump, and the hydraulic oil installed in the supply flow path between the pumps and the accumulator, respectively And a check valve for preventing back flow into the pump.

According to a preferred feature 4 of the present invention, the supply flow path between the pump and the check valve is branched to be installed in each of the flow paths communicating with the drain flow path, and switched from the initial state of closing the flow path by a predetermined signal. A flow path opening and closing valve is further provided.

According to a preferred feature 5 of the present invention, a loader including 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 portion of the work system. In the hydraulic system of the present invention, the regulator is provided in each of the branch flow path branched from the supply flow path from which the hydraulic fluid is discharged from each of the pumps, the regulator for switching the swash plate tilt angle of the pump in accordance with the change in the pressure of the branch flow path, An accumulator for accumulating hydraulic oil discharged from the pump, respectively installed on the pump; a check valve installed in a supply flow path between the pump and the accumulator, respectively, to prevent the hydraulic oil accumulated by the accumulator from flowing back to the pump; and the pump And a flow path that communicates with the drain flow path by branching a supply flow path between the check valve and the check valve. Each installed Further included is a flow path switching valve for switching a state of opening from the initial state to close the flow path by a predetermined signal.

Hereinafter, preferred embodiments of the present invention will be described based on the accompanying drawings.

1A and 1B show a hydraulic circuit diagram of a loader according to an embodiment of the present invention. As shown, there is provided a work system and a travel system driven by the hydraulic oil discharged through the oil passage 1A from the main pump 1 driven by the engine, and the travel system includes a steering wheel (not shown) of the operator. A steering system 3 for switching the hydraulic oil supplied through the oil passage 1A by means of a signal and a pair of steering cylinders for steering the equipment as driven by the hydraulic oil supplied by the steering system 3. 11, 12) and the cushion 13 to prevent the impact of the equipment during steering.

On the other hand, the work system includes a main control valve section 4 for switching the hydraulic oil supplied through the flow path 1A by the pilot signals a, b, cd, f, g, h, and the main control valve section 4. Dump cylinder 14 and lift cylinders 16 and 17 connected to the operation device and a relief valve 15 to determine the operating pressure of the hydraulic circuit by preventing a rise in the hydraulic line by a predetermined pressure or more. Is done.

In addition, the operation lever 5 is provided in the hydraulic oil supply passage 2A discharged from the pilot pump 2 and supplies a pilot signal to the main control valve unit 4 in proportion to the operator's signal, and the operation lever. A pilot signal supply unit 19 for controlling the hydraulic oil supplied to the unit 5 is provided.

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

The hydraulic device of the loader according to the present embodiment includes a recirculator 9 for varying the tilt angle of the swash plate of the main pump 1 so as to receive the pressure of the flow path 1A and change the discharge flow rate of the main pump 1. Accumulator 7 installed in the flow path 1A to accumulate excess hydraulic fluid discharged from the main pump 1 to maintain the operating pressure of the flow path 1A above a predetermined pressure so that the traveling system and the work system can be operated. And a check valve 6 for preventing backflow of the pressurized oil accumulated in the accumulator 7 toward the main pump 1 side.

The above-mentioned regulator 9 drives the pump to receive the pressure of the flow path 1A to increase the inclination angle of the swash plate of the main pump to maximize the discharge flow rate. In the no-load state, the swash plate tilt angle of the main pump is reduced to drive the discharge flow rate to the minimum. For this operation, the regulator 9 includes a servo cylinder 90 which connects the flow paths 90A and 90B branching off the flow path 9A communicating with the flow path 1A to both ends, and the servo cylinder includes a large chamber ( 91 and the small chamber 92, the piston 93 reciprocating in the servo cylinder 90, and is connected to one side of the swash plate of the main pump 1, the piston 93 is moved as the piston 93 moves A piston rod 94 for transmitting a switching force to change the tilt angle, an elastic member 95 installed in the small chamber 92 of the servo cylinder to elastically bias the piston 93 to the right end of the cylinder, and a flow path 90A and The flow path 90B is drained to the drain flow path 21A due to a difference between the orifice 96 provided in the connection flow path of the flow path 90B and the hydraulic pressure of the self-elastic member 98 and the hydraulic force acting on the flow path 90A. A proportional valve 97 is opened.

The elastic member 98 of the above-mentioned proportional valve is a variable elastic member in which the set elastic pressure can be varied by an operator's operation.

Further, a flow path is installed in the branch flow path 8A which branches the flow path 1A and connects with the drain flow path 21A, and switches from the initial state in which the flow path is closed by the valve spring to the open state. A flow path opening and closing valve 8 is further provided.

On the other hand, since the configuration of the regulator 10 for varying the swash plate tilt angle of the pilot pump is the same as that of the above-described regulator 9, detailed description thereof will be omitted.

Hereinafter, the operation and effects of the present embodiment configured as described above will be described.

First, when all the control valves of the equipment is operated in a neutral state (no load state), the pressure of the flow path (1A) will be increased to the set pressure of the relief valve 15 by the hydraulic oil discharged from the main pump (1) will be. That is, when the steering system-based supply passage 3A and the work-system-based supply passage 4A are closed circuits and the flow path opening / closing valve 8 is in a switched state to close the flow path, the flow path 1A is driven by the hydraulic oil discharged from the main pump 1. The pressure in) rises up to the set pressure of the relief valve 15. At this time, the accumulator 7 accumulates the hydraulic oil, and the regulator 9 will operate to make the discharge flow amount minimum by reducing the swash plate warp angle of the main pump 1. In detail, the force acting on one side of the piston 93 by the hydraulic pressure supplied to the inside of the large chamber 91 of the cylinder through the flow path 9A and the flow path 90A is applied to the orifice 96 and the flow path 90B. ), The hydraulic force supplied to the small chamber 92 of the cylinder and the elastic force of the elastic member 95 overcome the force acting on the other side of the piston 93 and the piston 93 moves to the left in the drawing. . At this time, the proportional valve 98 switches the pilot pressure due to the hydraulic force acting on the flow path 90A to overcome the elastic force of the elastic member 98 and communicate the flow path 90B with the drain flow path 21A. As a result, the proportional valve 98 returns the hydraulic oil in the small chamber 92 to the drain flow passage 21A in proportion to the movement amount of the piston 93. In this state, by varying the elastic force of the elastic member 98 it is possible to vary the amount and speed of movement of the piston (93).

In this state, when the flow path opening / closing valve 8 is opened, the flow path 8A and the drain flow path 21A communicate with each other so that the hydraulic oil of the main pump 1 does not pass through the hydraulic lines of the work system and the steering system. It is returned to the tank 21 without the flow path 1A to maintain the operating pressure at which the equipment can be driven by the accumulator 7.

On the other hand, when operating the work system, the steering system and each system at the same time in this state, the pressure oil accumulated in the accumulator (7) is supplied first, at the same time the flow path opening and closing valve (8) is switched to the channel closed state The hydraulic oil discharged from the main pump 1 is supplied. In this case, the swash plate inclination angle of the main pump 1 is increased to increase the discharge amount of the main pump 1. That is, as the pilot signal pressure 90A of the proportional valve 98 becomes smaller, the drain port is blocked to increase the pressure of the flow path 90B, and at the same time, the hydraulic force acting in the large chamber 91 of the cylinder becomes smaller. Accordingly, the piston 93 moves to the right in the drawing to increase the tilt angle of the swash plate of the main pump 1.

As described above, according to the hydraulic device of the loader according to the present invention, by reducing the flow rate discharged from the hydraulic pump at no load of the equipment to save the driving force of the engine to increase the efficiency of the equipment, maintaining a constant pressure in the hydraulic oil supply flow path This improves the reaction force of the equipment and communicates the discharge flow rate with the bypass flow path at no load, allowing the hydraulic pump to operate at no load, saving the driving force of the pump and preventing the heating of the device, thereby extending the pump life. Of course, by preventing the rise in oil temperature has the effect of reducing the performance degradation and damage of the work device.

Claims (8)

In the hydraulic system of a loader equipped with a main pump for driving a work system and a steering system, and a pilot pump for supplying hydraulic oil to an operating lever for supplying a pilot signal to a control valve portion of the work system: And a regulator installed in branch passages branched from the supply passages through which the working oil is discharged from each of the pumps, and configured to switch the swash plate tilt angle of the pump according to the change in the pressure of the branch passages. The method according to claim 1, wherein each regulator, A servo cylinder installed at one side of the pump; A first flow path branching the branch flow path and communicating with the large chamber side of the servo cylinder; A second flow path branching the branch flow path and communicating with the small chamber side of the servo cylinder; A piston installed inside the cylinder chamber to enable reciprocation and having one end connected to a swash plate of the pump; An elastic member installed in the small chamber to elastically bias the piston to the large chamber side; An orifice provided in a connection flow path where the first flow path and the second flow path are connected to limit a flow rate toward the second flow path; And The second flow path is provided on the flow path which branches the second flow path and communicates with the drain flow path, and receives the operating pressure of the first flow path as a switching signal and is switched in proportion to the size difference with the elastic pressure of the elastic member. Hydraulic device of the loader is configured with a proportional valve for draining The method of claim 2, wherein the elastic member of the proportional valve, Hydraulic device of the loader, characterized in that the variable elastic member that can be changed by the operator set elastic pressure. The method according to claim 1, Accumulators each installed on a supply flow path of the pump to accumulate hydraulic oil discharged from the pump; And And a check valve installed in a supply passage between each of the pumps and the accumulator to prevent the hydraulic oil accumulated by the accumulator from flowing back to the pump. The method according to claim 1, And a flow path opening / closing valve branching the supply flow path between the pump and the check valve to switch from the initial state of closing the flow path to an open state by a predetermined signal. The hydraulic system of the loader. In the hydraulic system of a loader equipped with a main pump for driving a work system and a steering system, and a pilot pump for supplying hydraulic oil to an operating lever for supplying a pilot signal to a control valve portion of the work system: A regulator installed in branch passages branched from supply passages through which hydraulic fluid is discharged from the pumps, respectively, for switching a swash plate tilt angle of the pump according to a change in pressure of the branch passages; Accumulators each installed on a supply flow path of the pump to accumulate hydraulic oil discharged from the pump; A check valve installed in each of the supply passages between the pumps and the accumulators to prevent the hydraulic oil accumulated by the accumulators from flowing back to the pumps; And It is provided with a flow path opening and closing valve for branching the supply flow path between the pump and the check valve and is provided in each of the flow path communicating with the drain flow path to switch from the initial state of closing the flow path to the open state by a predetermined signal. The hydraulic system of the loader. The method according to claim 6, wherein each regulator, A servo cylinder installed at one side of the pump; A first flow path branching the branch flow path and communicating with the large chamber side of the servo cylinder; A second flow path branching the branch flow path and communicating with the small chamber side of the servo cylinder; A piston installed inside the cylinder chamber to enable reciprocation and having one end connected to a swash plate of the pump; An elastic member installed in the small chamber to elastically bias the piston to the large chamber side An orifice provided in a connection flow path where the first flow path and the second flow path are connected to limit a flow rate toward the second flow path; And The second flow path is provided on the flow path which branches the second flow path and communicates with the drain flow path, and receives the operating pressure of the first flow path as a switching signal and is switched in proportion to the size difference with the elastic pressure of the elastic member. Hydraulic device of the loader is configured with a proportional valve for draining The method according to claim 7, wherein the elastic member of the proportional valve, Hydraulic device of the loader, characterized in that the variable elastic member that can be changed by the operator set elastic pressure.