JPS5935663Y2 - hydraulic excavator - Google Patents

Description

[Detailed description of the invention] This invention is a hydraulic system that performs excavation work by operating each part of the excavation equipment, which consists of a boom, an arm, and a packet attached to an upper rotating body, using a boom cylinder, an arm cylinder, and a packet cylinder. It concerns excavators.

In conventional hydraulic excavators of this type, there are two pumps - two
It has a valve-type hydraulic circuit configuration, and these two pumps and two valves operate the boom cylinder, arm cylinder, packet cylinder, and in addition to these, the hydraulic motors of the left and right traveling devices and the swing motor that drives the upper swing structure. However, with these conventional hydraulic circuit configurations, it is difficult to combine the swing system with large inertia and other actuators, so in recent years, in order to improve this, an additional hydraulic pump has been installed. Therefore, a configuration has been adopted in which the swing system is made independent using this hydraulic pump.

However, in this case, there are three hydraulic pumps, which causes a problem that the engine output is insufficient compared to the conventional case of two pumps.

To solve this problem, it would be better to improve the engine horsepower compared to the conventional method, but this means that the engine output cannot be fully utilized when the turning operation is not performed, so it is difficult to use the engine output effectively. There are some difficulties.

The present invention was developed in consideration of the above-mentioned issues, and it is possible to perform complex operations of the swing system without stalling the engine using an engine that has the necessary output to operate the work equipment and the traveling device. An object of the present invention is to provide a hydraulic excavator that can effectively utilize engine output sufficient to operate a traveling device.

The stealing will be explained below based on the embodiment shown in the drawings.

1, 2.3, the first, second, and third pumps are driven by the same engine 6.

Of the above-mentioned pumps, the first and second pumps 1 and 2 take over the main pump, and the discharge oil of the first pump 1 is transferred to the first pump consisting of the right traveling operation valve 4a, the boom operation valve 4b, and the packet operation valve 4c. The oil discharged from the second pump 2 flows to the second operating valve 5, which includes a left travel operating valve 5a, an arm operating valve 5b, and a service valve 5C.

On the other hand, the oil discharged from the third pump 3 flows independently to the swing operation valve 7.

Although not shown, each of the above operating valves is connected to a respective actuator.

Further, the switching operation of each of the above-mentioned operation valves is performed by pilot pressure.

That is, 8 is a pilot valve for right travel, 9 is for left travel, 10 is a pilot valve for packet and boom, and 11 is a pilot valve for arm and swing, and by operating these, the pressure from pilot pump 12 is controlled. Oil is selectively supplied to each operating valve to switch between them.

The first and second hydraulic pumps 1 and 2 are of variable discharge type, and their flow rates are controlled by servo valves 13 controlled by respective discharge pressures.

The servo valve 13 is connected to the first and second hydraulic pumps 1 and 2.
A first piston 15 is connected to each of the adjustment members 1a, 2a via a servo rod 19, and this piston 15 is connected to the first and second hydraulic pumps 1, 1 through the adjustment members 1a, 2a.
The first spring 14 biases in the direction in which the amount of work of No. 2 increases.
a second piston 18 that receives the first spring 14; a second spring 17 that receives the second piston 18 against the first spring 14; and the first and second pistons. 15 and 18, and the first piston 15
The first piston 1.2 is opposed to the end face of the first piston 1.2 and generates pressure that biases the first piston 15 via the adjustment members 1a and 2a in a direction that reduces the amount of work of the first and second hydraulic pumps 1.2. Hydraulic chambers 13b and 13c and a cylinder 13a which has a second hydraulic chamber 16 that faces the end face of the second piston 18 and generates pressure that biases the biasing force of the first spring 14 in a direction that weakens the biasing force of the first spring 14. It has become.

The second hydraulic chamber 16 facing the second piston 18 of the servo valve 13 is connected to the pilot pump 12 via a normally closed electromagnetic switching valve 20.

The electromagnetic switching valve 20 is configured to be opened by energizing a solenoid when the swing pilot valve 11 is operated.

In the above-mentioned stealing, when operating the working machine and the traveling device, the first and second operation valves 4.5 are used as the pilot valve 8.5. 9
．． 10. 11 by operating through
At this time, the oil discharged from the first and second hydraulic pumps 1.2 is used.

At this time, since the swing operation valve 7 is in the neutral position, the third pump 3 is completely drained and does not become a load on the engine.

Further, the first and second hydraulic pumps 1 and 2 at this time are adjusted by the servo valve 13 according to the respective hydraulic circuit pressures.

Next, when the swing operation valve 7 is switched by operating the swing pilot valve 11 to operate the swing operation while operating the work equipment and traveling device, pressure is generated in the circuit of the third hydraulic pump 3 and the swing motor is driven. At the same time, the switching valve 20 is opened and the pilot pump 12 is turned.
The hydraulic pressure from the servo valve 13 acts on the hydraulic chamber 16 facing the second piston 18 and moves it against the spring 17, thereby increasing the set load of the spring 14 supporting the first piston 15. The servo valve 13 is set so that the horsepower consumption of the first and second hydraulic pumps 1 and 2 becomes smaller.

The present invention is as described above, and three hydraulic pumps 1, 2゜3 are provided so as to be driven by one engine 6, and among these, the first and second hydraulic pumps 1, 2 are driven by the discharge pressure. It is of a variable discharge type that is adjusted by an operating servo valve 13, and is connected to operation valves for working equipment and traveling equipment, and a third hydraulic pump 3 is connected to a swing operation valve, and In a hydraulic excavator in which each of the operation valves described above is switched and operated by pilot pressure from a pilot valve, when a so-called combined operation is performed in which the work machine, travel gear and swing gear are operated simultaneously, the work machine and travel gear are switched. The horsepower consumption of the first and second hydraulic pumps 1 and 2 for driving can be reduced, and the combined operation of the swing system can be performed without stalling with an engine that has the output necessary to operate the work equipment and traveling equipment. This makes it possible to effectively utilize the engine output sufficient to operate the working machine and the traveling device.

Further, according to the present invention, the second hydraulic chamber 16 of the servo valve 13
The switching valve 20 is connected to the pilot pressure source through the switching valve 20, which opens when the swing pilot valve 11 is operated and communicates with the drain circuit when closed. The responsiveness of the operation of the second piston 18 of the servo valve 13 can be improved in accordance with the switching operation.

[Brief explanation of the drawing]

The drawing is a hydraulic circuit diagram of a hydraulic excavator according to the present invention. 1.2.3 is a hydraulic pump, 6 is an engine, 11 is a pilot valve for swinging, 13 is a servo valve, 14 is a spring, 15 is a first screw I/N, 16 is a hydraulic chamber, and 17 is a second piston.

Claims (1)

[Scope of utility model registration request] Three hydraulic pumps driven by one engine 6 1. 2. 3, of which the first and second hydraulic pumps 1 and 2 are of variable discharge type that is adjusted by a servo valve 13 operated by discharge pressure, and these are operated by operating valves for working machines and traveling equipment. In a hydraulic excavator, the third hydraulic pump 3 is connected to the swing operation valve 7, and each of the operation valves is switched by pilot pressure from a pilot valve.
3, each adjustment member 1 of the first and second hydraulic pumps 1 and 2
a, 2a, and a first piston 15 that urges the piston 15 in a direction that increases the amount of work of the first and second hydraulic pumps 1, 2 via the adjustment members 1a, 2a. a spring 14; a second piston 18 that receives the first spring 14; a second spring 17 that receives the second piston 18 against the first spring 14; The pistons 15 and 18 of the first and second hydraulic pumps 1 and 2 are fitted, and the first piston 15 is connected to the first and second hydraulic pumps 1 and 2 through adjustment members la and 2a. The first hydraulic chambers 13b, 13c and the second piston 1 generate pressure that biases the work in a direction that reduces the amount of work.
a second hydraulic chamber 16 that faces the end face of the spring 8 and generates pressure that biases the biasing force of the first spring 14 in a direction that weakens the biasing force of the first spring 14;
This servo valve 1 is composed of a cylinder 13a having a
The first hydraulic chambers 13b and 13c of No. 3 are connected to the respective discharge circuits of the first and second hydraulic pumps 1 and 2 via a pilot circuit, and the second hydraulic chamber 16 and a pilot pressure source are connected to each other via a pilot circuit.
It opens when the pilot valve 11 for turning is operated,
A hydraulic excavator characterized in that the hydraulic excavator is connected via a switching valve 20 which communicates with a drain circuit when closed.