JPS5923099Y2 - pressure fluid circuit - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a pressure fluid circuit used in, for example, construction machinery, and particularly relates to a pressure fluid circuit that efficiently utilizes engine output.

Conventionally, in pressure fluid circuits used in construction machines such as excavators, in order to effectively utilize the output of the engine that drives the pumps and to simplify the circuit, a plurality of coaxial pumps are simultaneously driven by the engine. Among actuators that receive fluid supply and discharge from a fluid circuit, those that require high speed are supplied by merging the discharge pressure fluid of the plurality of pumps, and those that require high torque are supplied by the plurality of pumps. which one of them drives only one and the other
By placing the pump in a no-load operating state, high-pressure, low-flow pressure fluid was supplied, thereby making effective use of engine output.

According to this circuit, when obtaining high pressure and low flow rate, the engine output is concentrated in one pump, for example, θ. Therefore, even if there is surplus engine output, the pump capacity (rated discharge pressure) will be reduced.

), the engine power cannot be utilized.

Therefore, a high performance pump was required.

This invention solves the above-mentioned problems by providing a device for recovering engine output between the discharge side of the pump and the fluid circuit.

Hereinafter, one embodiment of this invention will be described with reference to the drawings.

The first pump 1 and the second pump 2 are coupled coaxially and are driven by a twin engine 3.

The first and second pumps 1 and 2 suck fluid from a tank 4 when driven by an engine 3 and discharge pressurized fluid into circuits 5 and 6.

The switching valve 7 has two switching positions 7a, 7b,
The operator can select and operate as desired.

The switching position 7a is the input port 9, 8 to which the circuits 5, 6 are connected.
and 1. to be described later. A power recovery device 13 (hereinafter referred to as a tuner) is connected to the second fluid circuit 21, 20.

) and a discharge port 12 connected to the discharge circuit 14 (in switching position 7b).
This case also has an input port, an output port, and a discharge port similar to those described above.

These are indicated by adding a to each number.

) When the switching valve 7 is operated to the switching position 7a as shown in the figure, the discharge pressure fluid of the first pump 1 is transferred to the input port 9. Outlet 1
This is a so-called no-load operation in which the water flows out into the tank 4 via the second discharge circuit 14.

The discharge pressure fluid of the second pump 2 flows into the input port 8, is divided within the switching valve 7, and flows out to the blade ports 10 and 11.

Note that the pressure control valves 15 and 16 are the first pressure control valves 15 and 16. Second fluid circuit 21
．． The required pressure of the actuator operated by each of the 20 switching valves is set.

(In the case of this embodiment, the pressure control valve 15 is the pressure control valve 1
The pressure is set higher than the set pressure of 6.

) The tuner 13 is, for example, a gear motor 13a, 13
It has a configuration in which two b are coaxial, and its input port 17 a
, 17b is connected to the output port 10.11 of the switching valve 7,
The output ports 18a, 18b are the first. The gear motors 13 a , 13 b are connected to the input ports 2 , 2 a , 22 of the second fluid circuit in relation to each other.
a, the pressure fluid flowing into 17b and the second. First fluid circuit 2
Output port 18a regardless of the load condition of 1.20
, 18b always discharge the same amount of pressure fluid.

(Although the flow rates of the pressure fluid discharged to the output ports 18a and 18b are the same in this embodiment, they can be varied, for example, by 2 or 3, if necessary.

) The second fluid circuit 20 includes a slide switching valve 23 that supplies and discharges fluid to a slide cylinder that moves the swivel table to either the left or right crawler side, and a slide switching valve 23 that supplies and discharges fluid to a fluid motor that drives the right crawler. A switching valve 24 for right travel and a switching valve 25 for turning that supplies and discharges fluid to and from a fluid motor that drives the turning table are connected in parallel.

The unload circuit 26a is activated when each switching valve 23, 24, 25 of said second fluid circuit 20 is in a neutral position and connects the input port 22 and the outlet 26.

The first fluid circuit 21 includes a left travel switching valve 27 that supplies and discharges fluid to a fluid motor for driving the left crawler, a packet switching valve 28 that supplies and discharges fluid to and from a packet drive cylinder, and a fluid motor for driving a boom. Boom switching valve 29 that supplies and discharges
, is equipped with an arm switching valve 30 for supplying and discharging fluid to and from the arm drive cylinder, and the left travel switching valve 27, packet switching valve 28, and boom switching valve 9 are connected in parallel to form a boom switching valve. The valve 29 and the arm switching valve 30 are formed by being connected in tandem.

The unload circuit 31 is activated when each of the switching valves 27 to 30 is in the neutral position, and the unload circuit 31 is connected to the manual port 22a and the discharge circuit 1.
4 is connected to the outlet 32.

The circuit 33 is connected to the outlet 26 of the second fluid circuit 20 via the check valve 34, and the other end is connected to the inlet side of the arm switching valve 30 of the first fluid circuit 21 and the unload circuit 31. .

Note that the check valve 34 is provided so that the direction from the second fluid circuit 20 to the first fluid circuit 21 is the forward direction.

Note that the first fluid circuit 20 has an actuator that requires relatively low power, and the second fluid circuit 21 has an actuator that requires high power.

The operation of this embodiment will be described below.

In the illustrated state, the engine 3 operates the first. 2nd pump 1
, 2, the first . The second pumps 1 and 2 are the tank 4
Fluid is sucked in from the circuits 5 and 6, and pressure fluid is discharged into the circuits 5 and 6.

The pressure fluid of the circuit 5 is supplied to the input port 9 and the discharge port 12 of the switching valve 7.
, flows out into the tank 4 via the discharge circuit 14.

The pressure fluid in the circuit 6 flows from the input port 8 of the switching valve 7 to the output port 1.
0.11, the gear motor 13 a of the tuner 13
, 13b, the second . It flows into the inlet 22.22H of the first fluid circuit 20.21.

The pressure fluid flowing into the second fluid circuit 20 flows through the unload circuit 26a, the outlet 26, the check valve 349 circuit 33. Unload circuit 31 of first fluid circuit 21. It flows out from the discharge circuit 14 into the tank 4 via the outlet 32.

The pressure fluid flowing into the first fluid circuit 21 is transferred to the unload circuit 31. Exit 32. It flows into the tank 4 via the discharge circuit 14.

In this state, both the first and second pumps 1 and 2 are in unload operation.

Next, when the packet switching valve 28 of the first fluid circuit 21 is operated, the discharge pressure fluid of the gear motor 13a of the tuner 13 flows into the packet cylinder.

At this time, the discharge fluid pressure of the second pump 2 increases to the set pressure of the pressure control valve 15 in accordance with the load acting on the packet.

This fluid pressure is applied to the gear motor 13a of the tuner 13,
It acts on the input ports 17a and 17b of 13b.

Therefore, the gear motor 13a receives the driving force of the gear motor 13a, and discharges a pressure fluid higher than the discharge fluid pressure of the second pump 2 to its output port 18a, and the packet is
A pressure fluid having a pressure higher than the discharge fluid pressure of the second pump 2 is supplied.

At this time, the first pump 1 is in unload operation, and the output of the second pump 3 is concentrated only in the second pump 2.

Next, operate the switching valve 7 to the second switching position 7b, and
．． Selector valve 25 for right and left travel of the first fluid circuit 20.21
．． 27 at the same time, the 1st. 2nd pump 1, 2
The discharge pressure fluid is supplied to the input port 9a of the switching valve 7.

8a flows into the input ports 17a, 17b of the gear motor of the tuner 13 via the output ports 11a, 10a.

In this tuner 13, the first . The flow rate of the discharge pressure fluid of the second pumps 1 and 2 is adjusted, and the output ports 18 b and 18
Since the same amount of pressurized fluid is discharged to a and supplied to the motors for driving the right and left crawlers, the straight forward movement of the excavator is maintained.

At this time, the first. The discharge fluid pressure of the second pumps 1 and 2 is
The pressure increases to the level set by the pressure control valve 16.

In other words, it is operated at low pressure and large flow rate.

In the above configuration, the pressure control valves 15 and 16 may be of the same pressure.

This device, which has the above-mentioned configuration and function, is equipped with a power recovery device between the pressure fluid source and the fluid circuit, so it is possible to obtain pressure fluid that exceeds the capacity of the pressure fluid source, and the effective output of the engine is increased. It has the effect of being able to measure its usage.

[Brief explanation of drawings]

The figure shows a fluid circuit of an embodiment in which this invention is applied to an excavator. 1 First balance 1 2... Second pump Pressure fluid source 3... Engine 4... Tank, 7... Switching valve, 7a.
...First switching valve, 7b... Second switching valve,
13... Tuner (power recovery device), 20...
...Second fluid circuit, 21...First fluid circuit.

Claims (1)

[Scope of utility model registration request] A pressure fluid source formed by simultaneously driving a plurality of pumps; a first pressure fluid source equipped with a switching valve that controls supply and discharge of fluid to a plurality of actuators; a second fluid circuit; a first switching position in which each of the discharge sides of the pumps of the pressure fluid source is connected to an input port, and each of the discharge sides of the pump is connected to an output port; a switching valve having a second switching position that connects to the output port of the switching valve and diverts the discharge side of the other pump to the output port; A pressure fluid circuit characterized in that a power recovery device is provided between the second fluid circuit and the flow rate of the pressure fluid from the switching valve at a fixed ratio.