JPS5934336A - Concurrent operation circuit for 2-pump system - Google Patents

Abstract

PURPOSE:To prevent the lowering of the revolving number of a running motor by a method in which check valves and an orifice are provided to the communication path for a direction switching valve to control an actuator and a parallel feeder, and a pilot path is led to a spring chamber. CONSTITUTION:The concurrent operation circuit of a pump system is made up of direction switching valves 3 and 7, running motors 11 and 12, a direction switching valve 6 to control a soil discharge cylinder 13, an orifice 24, spring chambers 27 and 28, parallel feeders 17 and 18, and check valves 19 and 20. When switching valves 3 and 7 are switched and the switching valve 6 is switched under the condition that the motors 11 and 12 are being turned, a pressure difference is produced before and back of the orifice 24, the pressures of the parallel feeders 17 and 18 become higher than those of the spring chambers 27 and 28, the check valves 19 and 20 are opened, and the same amounts of fluid discharged flow from the pumps 1 and 2 into the cylinder 13. The straightforward running of a shovel is made possible without any change in the revolving number of the motors 11 and 12.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a simultaneous operation circuit for a two-pump system that operates a predetermined actuator using two pumps, such as a control circuit for a power shovel.

(Conventional Operation Circuit) As a conventional operation circuit of this type, an operation circuit for a power shovel shown in FIG. 1 has been known.

The operating circuit shown in FIG. 1 includes two circuit systems, and pumps 1 and 2 are connected to each circuit system.

A plurality of directional switching valves 3 to 6 and 7 to 10 are connected to each of the above circuit systems, and each of these directional switching valves is configured to control a predetermined actuator connected to it.
The directional control valve 3 of one circuit system is connected to the drive motor 11 of one side.
The directional switching valve 7 of the other circuit system controls the other travel motor 12, and the directional switching valve 6 controls the earth removal plate cylinder 13.

Each directional valve as described above, when held in the neutral position shown, has its tandem passage 14.1
5 is completely passed through, and the oil from the pump 1.9 returns to the tank 16.

When the directional control valve is switched, oil is supplied to the pumps 1 and 2 via parallel feeders 17 and 18.

Therefore, if only the directional switching valve 6 that controls the earth removal plate cylinder 13 is switched to the left or right and all other directional switching valves are held at the neutral position, the oil from the pump 1 is transferred to the parallel feeder 17. The soil flows into the soil removal plate cylinder 13 through the soil discharge plate cylinder 13 and is activated.

In addition, by switching the directional control valve 3.7, the travel motor 11.12
When the directional control valve 6 is switched while the vehicle is rotating, the oil from the pump 1 is distributed between the travel motor 11 and the earth removal plate cylinder 13.

However, although the discharge amount of the pump 1 of one circuit system is distributed between the traveling motor 11 and the discharge plate cylinder 13, the one traveling motor 11 is distributed to the traveling motor I2 of the other circuit system.
The rotation speed will drop.

For this reason, the conventional operating circuit described above has a drawback that if the earth removal plate cylinder 13 is operated to perform ground leveling work while the power shinnibel is running, the vehicle cannot travel straight ahead.

(Objective of the present invention) An object of the present invention is to provide an operation circuit that prevents the rotational speed of, for example, a travel motor provided in both circuit systems from changing even when an actuator connected to one circuit system is driven. shall be.

(Embodiments of the present invention) The present invention will be described in detail below, and elements that are the same as those of the prior art will be described using the same reference numerals while omitting the details.

Accordingly, in the first embodiment shown in FIG. 2, check valves 19, 20 are provided in the path that communicates the parallel feeder 17, 18 with the earth removal plate cylinder 13.

Both check valves 19, 20 are configured to allow oil from the parallel feeders 17, 18 to flow only to the communication path 21 common to both.

Further, the communication passage 21 is configured to flow into the direction switching valve 6 that controls the earth removal plate cylinder 13 via an oil passage 22 and a load check valve 23.

As shown in the figure, an orifice 24 is provided in the oil passage 22, and pilot passages 25 and 26 are connected to the downstream side of the orifice 24.

Each of the two pilot passages 25.26 is connected to a spring chamber 27.28 of the check valve 19.20, and the pilot pressure from the pilot passage 25.26 creates a back pressure against the check valve 19.20. I am trying to make it work as a.

Therefore, by switching only the directional control valve 3, the earth removal plate cylinder 1 is
3, the oil from the pump 2 returns to the tank 16, while the oil from the pump 1 pushes open the check valve 19 and flows into the directional control valve 6, from which it flows into the first upper plate cylinder 1.
3.

In addition, by switching the directional control valve 3.7, the travel motor 11.12
When the directional control valve 6 that controls the exhaust plate cylinder 13 is switched while rotating the orifice 24, the orifice 24 is rotated.
A pressure difference occurs before and after, and the pressure on the parallel feeder 17.18 side becomes higher than the pressure in the spring chamber 27.28, so both check valves 18.20 open.

When both check valves are opened as described above, each of the discharge amounts of the pumps 1.2 flows into the earth removal plate cylinder 13.

As described above, in this embodiment, the discharge amount of both pumps 1.2 flows into the discharge plate cylinder 13 in equal parts, which is different from the conventional circuit in which only the discharge amount of one pump flows into the discharge plate cylinder 13. are different, the rotational speed of the one-region motor becomes the same, and the power shovel can travel straight ahead.

The second embodiment shown in FIG.
．． An orifice 29 separate from the orifice 24 is provided in the oil passage 22 on the downstream side of the oil passage 28, and the rest is the same as in the first embodiment.

However, in this second embodiment, the directional control valve 3.7 is switched to rotate the travel motor 11.12, and at the same time,
When the directional switching valve 6 that controls the earth removal plate cylinder 13 is switched, oil from both pumps 1 and 2 flows into the earth removal plate cylinder 13 in the same manner as in the first embodiment.

However, in this second embodiment, as described above, the orifice 29 is provided on the downstream side of the pilot passages 25 and 26, so when, for example, only oil from one pump 1 is supplied to the earth removal plate cylinder 13, The other check valve 20 will not open inadvertently.

That is, when driving the earth removal plate cylinder 13 with only oil from one pump 1'' as described above, since the orifice 29 is located downstream of the pilot passage 25.26, the spring chamber 27 is removed from the pilot passage 25.26. .28 is higher than in the first embodiment. Therefore, the back pressure acting on the check valve 20 increases, making it difficult to open the check valve 20.

(Structure of the present invention) As is clear from the above description, the present invention connects a pump to each of two circuit systems, provides a plurality of directional switching valves in each of these circuit systems, and uses each directional switching valve to perform a predetermined operation. In the simultaneous operation circuit of the two-bonsea system, which is configured to control the actuator of the actuator, and to supply oil from the pump via the parallel feeder when the directional control valve is switched, the specific actuator that controls the actuator is A check valve connected to each parallel feeder is provided in the path that communicates the directional switching valve with the parallel feeders of both circuit systems, an orifice is provided downstream of this check valve, and an orifice is provided downstream of this orifice. , a pilot passage communicating with the spring chamber of each check valve is provided.

With the above configuration, oil from the pumps of both circuit systems flows from the parallel feeder to a specific actuator via the check valve.

(Effects of the present invention) For example, in the operation circuit of a power shovel, even when driving the earth removal plate cylinder while rotating the travel motor, the oil from the pumps of both circuit systems is distributed equally to the earth removal plate cylinder. Therefore, the rotational speed of the delimiting motor is always the same, and the path of the power shovel is not bent.

[Brief explanation of the drawing]

Figure 1 is a conventional circuit diagram, Figure 2 is the first diagram of this invention.
FIG. 3 is a circuit diagram of the second embodiment. 1.2...Fist pump, 3~lO...Direction switching valve, 17
．． 18 lives/kai no kurarerufuita゛, 19.20...
Check valve, 24...orifice, 25.26/e fist pilot passage, 27.2811...if chamber. Representative Patent Attorney Nobuyuki Shima

Claims (1)

[Claims] A pump is connected to each of the two circuit systems, a plurality of directional switching valves are provided in each of these circuit systems, and each directional switching valve controls a predetermined actuator, and when the directional switching valve is switched, the parallel feeder is In a simultaneous operation circuit for a two-pump system configured to be supplied with oil from a pump through A two-pump system comprising a check valve connected to the parallel feeder, an orifice downstream of the check valve, and a pilot passage communicating with the spring chambers of the check valves downstream of the orifice. simultaneous operation circuit.