JPS6233949A - Oil-pressure circuit for oil-pressure machine - Google Patents

Abstract

PURPOSE:To suppress the amount of pressure oil to be leaked by a method in which the upstream sides of the first and second direction switching valves with each other, ports on the downstream sides of both the switching valves are connected to the bottom side of a cylinder, and the other ports on the downstream side of the first direction switching valve is connected to the rod side of the cylinder. CONSTITUTION:Pressure oil is supplied through the first and second oil-pressure pumps 50 and 52 to the first and second direction switching valve groups 51 and 53 including the first and second direction switching valves 1 and 2. The upstream sides of the valves 1 and 2 are connected with pipelines 40 and 41 with check valves 13 and 14. Ports 3 and 5 on the downstream sides of the valves 1 and 2 are connected with the bottom side 30 of an arm cylinder 107 by a pipeline 31, and the port 4 on the downstream side of the valve 1 is connected with the rod side 32 of the cylinder 107 by a pipeline 33. When the arm is kept in an inoperative state(or in a downtime condition), it is possible to prevent the transmission of pressures held on the rod side of the cylinder 107 to the valve 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a hydraulic circuit that is installed in a hydraulic machine such as a hydraulic excavator and is configured to combine pressure oil from a plurality of hydraulic pumps and drive a hydraulic cylinder.

[Background of the invention]

FIG. 2 is a side view showing the external appearance of a hydraulic excavator taken as an example of this type of hydraulic machine, and FIG. 3 is an explanatory diagram illustrating the operation of the working machine portion of the hydraulic excavator shown in FIG.

The hydraulic excavator shown in FIG. 2 includes a traveling body 102 that is driven by a traveling device 101, a rotating body 104 that is placed on the traveling body 102, and that is rotated by a swing motor 103.
A boom 106 is rotatably mounted on the revolving body 104 and driven by a boom cylinder 105; an arm 108 is rotatably mounted on the boom 106 and driven by an arm cylinder 107; A packet 110 is attached to the packet cylinder 109 and driven by a packet cylinder 109. Reference numeral 111 indicates an operating lever 1 that is arranged in the driver's cab and drives, for example, the arm cylinder 107. Note that the above-mentioned boom 106, arm 108, packet 110, etc. constitute a working machine.

The hydraulic excavator configured in this manner is configured such that, for example, by operating the operating lever 111 and contracting the arm cylinder 107, the arm 1 is moved as shown by the arrow 112 in FIG.
08 can be placed in a dump (raised) state, and by extending the arm cylinder 107, the arm 108 can be placed in a cloud (down) state as shown by the arrow 113 in FIG.
It is possible to perform excavation work of desired earth and sand.

Further, FIG. 4 is a circuit diagram showing a schematic configuration of a conventional hydraulic circuit included in the hydraulic excavator shown in FIG. 2. Reference numeral 50 denotes a first hydraulic pump, and the switching valve 1 including the directional switching valve 54 for the swing motor 103 and the first directional switching valve 1 for the arm cylinder 107 located downstream thereof is connected to the cylinder bottom side 30.
A feeder boat 8 is supplied with pressure oil from the center bypass through a load check 6, and a cylinder is connected to the cylinder rod side 32 via a pipe 33. The feeder boat 9 is provided with a boat 4 and a feeder boat 9 to which pressure oil is supplied from a parallel circuit 55 via a load check 7. Note that a conduit 10 is provided in the conduit that communicates the conduit portion located between the load check 6.7 and the directional control valve 1.

This directional switching valve 1 allows the combined operation of the swing motor 103 and the arm cylinder 107 to be performed well.
By supplying 3vc pressure oil from the feeder boat 8 through the parallel circuit 55 and throttle 10 during a combination of arm cloud operation with low load pressure and swing operation with high load pressure.

By restricting a large amount of pressure oil from flowing into the cylinder bottom side 30 where the load pressure is low and supplying pressure oil to the swing motor 103 where the load pressure is high, only the arm cloud operation is performed and the swing operation is not performed. It prevents Also,
During arm dump operation with high load pressure and combined swing operation,
Restriction 10 from parallel circuit 55 to cylinder rod side 32
Workability can be maintained because pressure oil can be supplied from the center bypass to the cylinder bottom side 30 without going through the pressure oil throttle 10 when the arm cloud is used alone.

Further, 52 is a second hydraulic pump, and the arm cylinder 10
Pressure oil is supplied to a second directional switching valve group 53 including a second directional switching valve 2 for merging. Directional switching valve 2 connects feeder boat 11 and arm cylinder 1
It has a cylinder boat 22 connected to the bottom side 30 of 07 and a cylinder port 5 connected to the rod side 32,
It is switched at the same time as the directional control valve 1 is switched by the operation lever 111, and the pressure oil of the second hydraulic pump 52 is made to join the pressure oil of the first hydraulic pump 50 and can be supplied to the arm cylinder 107.

By the way, since the arm cylinder 107 described above is a single rod type, there is a difference in the pressure receiving area of the bottom side 30 and the rod side 32. For example, the pressure receiving area of the rod side 32 is 1/2 of the pressure receiving area of the bottom side 30. It is set to be about. For this reason, when the arm is dumped as shown in Fig. 2, the third
Bucket at each of the arm cloud times shown in the figure)
Even if an equal load W is applied to the portion 110, the holding pressure generated on the rod side 32 during arm dumping shown in FIG. 2 will be equal to the pressure receiving area ratio of the holding pressure generated on the bottom side 30 during arm clouding shown in FIG. It will be twice as much, that is, about twice as much. On the other hand, leakage of pressure oil from the bow) 4.5 of the directional control valves 1 and 2 to the low pressure side is generally unavoidable due to the design, and especially during arm dumping as shown in Fig. 2 when the holding pressure is high, the two directional control valves Since the leakage occurs through the valve 1.2, the amount of leakage is large, and since the area of the rod side 320 is small, even with the same amount of leakage, the amount of movement of the arm cylinder 107 becomes larger. Therefore, there is a problem that the natural movement amount, that is, the natural descent amount of the arm 10B becomes large.

Note that although the arm 108 has been described above, the same thing can happen to the packet 110 as well.

[Purpose of the invention]

The present invention has been made in view of the practical problems in the prior art, and its purpose is to reduce the amount of pressure oil leakage that occurs when a work machine component such as an arm is held in a predetermined stopped state. The object of the present invention is to provide a hydraulic circuit for a hydraulic machine that can be suppressed.

[Summary of the invention]

To achieve this object, the present invention provides a first hydraulic pump, a first directional valve group connected to the first hydraulic bonder and including a first directional valve for driving a cylinder; 2 hydraulic pump, connected to this second hydraulic pump,
A second directional switching valve group including a second directional switching valve for merging is provided, and by operating the second directional switching valve, the pressure oil of the first hydraulic pump and the pressure of the second hydraulic pump are changed. In the device in which oil is combined with oil and supplied to the above-mentioned cylinder via the first directional control valve, the upstream side of the first directional control valve and the second
A pipe connecting the upstream side of the directional control valve, one boat located downstream of the first directional control valve, and one boat located downstream of the second directional control valve are connected to the bottom of the cylinder. This configuration includes a pipe line communicating with the rod side of the cylinder and a pipe line communicating the rod side of the cylinder with another boat located downstream of the first directional control valve.

[Embodiment 1 of the Invention] The following five hydraulic circuits of a hydraulic machine of the present invention will be explained based on the drawings.

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

In this figure, parts equivalent to those shown in FIGS. 2 to 4 described above are designated by the same reference numerals.

In this embodiment, the pipe line 40 has one end connected to the upstream side of the second directional switching valve 2 for one merge, that is, the boat 11.
, 41 are provided, the other end of the pipe 4o is connected to the pipe provided with the throttle 10, and the other end of the pipe 41 is connected to the boat 9 of the first directional control valve 1 and the rod check 7. It is connected to the conduit section located between. 13.1'4 is a check valve interposed in the middle of the pipe line 40°41. Also, one boat 3 located downstream of the first directional switching valve 1 and one boat 5 located downstream of the second directional switching valve 2 are connected to the bottom side 30Vc of the arm cylinder 107.
They are communicated via a conduit 31.

In addition, another boat 4 located downstream of the first directional control valve l and the rod side 32 of the arm cylinder 107 are connected to a conduit 33.
Please contact me via. Other configurations are as described above.
This is equivalent to the hydraulic circuit shown in the figure. However, in the case shown in FIG. 4, the boat 22 located downstream of the second directional control valve 2 was communicated with the bottom side 30 of the arm cylinder 107, but in the case shown in FIG. In the example.

The portion corresponding to the boat 22 is blocked.

In this embodiment, as in the conventional case, when the arm cloud operation with low load pressure and the turning operation with high load pressure are combined, the feeder boat 8 is passed through the parallel circuit 55 and the throttle 10 to the cylinder boat 3 to the cylinder bottom side 30. By supplying pressure oil to the cylinder, it is possible to carry out a combined operation of arm cloud operation and rotation, and during the combined operation of arm dump operation and rotation with high load pressure, the parallel circuit 55 is connected to the cylinder rod side 32 without going through the throttle 10. can supply pressure oil to
Moreover, when the arm cloud is used alone, pressure oil can be freely supplied from the center bypass to the cylinder bottom side 30 without passing through the throttle 10.

Further, when operating the arm cloud, the operation lever 111 switches the first directional switching valve 1 and the second directional switching valve 2 to the first directional switching valve 1 and the second directional switching valve 2.
They are respectively switched to the left position in the figure, and the center bypass of the directional control valve 2 is closed. This causes the pressure oil of the second hydraulic pump 52 to flow to the check valve 13 and the pipe ii! 40 to the cylinder bottom side 30 of the arm cylinder 107. Furthermore, during arm dump operations that require high working speed, the first directional control valve 1 and the second directional control valve 2 are respectively switched to the right position in FIG.
The pressure oil of the second hydraulic pump 52 is supplied to the check valve 14. Conduit 4
1 to the first hydraulic pump 50
is combined with the pressure oil of the arm cylinder 107 and supplied to the cylinder rod side 32 of the arm cylinder 107.
port 3 and the boat 5 of the second directional control valve 2, that is, the cylinder bottom side 30 of the arm cylinder 107, are connected to the tank. With these, workability equivalent to that of the conventional method can be obtained. Note that during the above-mentioned arm cloud operation, oil is returned to the tank only through the directional control valve 1, but this does not cause any problem because the flow rate is reduced due to the area ratio of the arm cylinder 1070 as described above.

In the embodiment configured in this manner, when the arm 108 is held in the inactive state in the arm dump state shown in FIG. 2, a holding pressure is generated on the rod side 32 of the arm cylinder 1070 shown in FIG. This holding pressure is transmitted through the pipe line 33, but the person connected to the pipe line 33 is the directional control valve 1, which means that the holding pressure at this time is not transmitted to the directional control valve 2. Therefore, leakage of pressure oil due to this holding pressure occurs only in the directional control valve I, and therefore the amount of leakage can be suppressed.

〔Effect of the invention〕

Since the hydraulic circuit of the hydraulic machine of the present invention is configured as described above, it is possible to ensure good workability of the work machine constituent members such as the arm as in the past, and also to stop the work machine constituent members at a predetermined time. It is possible to suppress the amount of leakage of pressure oil that occurs when the work machine is held in this state compared to the conventional method, and it has the effect of reducing the amount of natural movement such as the amount of natural descent of the components of the working machine.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the hydraulic circuit of the hydraulic machine of the present invention, Fig. 2 is a side view showing the external appearance of a hydraulic excavator taken as an example of the hydraulic machine, and Fig. 3 is shown in Fig. 2. FIG. 4 is an explanatory diagram illustrating the operation of a working machine portion of a hydraulic excavator, and FIG. 4 is a circuit diagram showing a schematic configuration of a conventional hydraulic circuit provided in the hydraulic excavator shown in FIG. l...First directional control valve, 2...@2
Directional switching valve, 3,4,5...Cylinder boat, 8,9゜11...Feeder boat), 13,1
4...Check valve, 30...Cylinder bottom side, 31.33...Pipe M, 32...
...Cylinder rod side, 40.41...Pipe line,
50...First hydraulic pump, 51...
First directional valve group, 52... Second hydraulic pump. 53...Second directional valve group.

Claims (1)

[Claims] 1. A first hydraulic pump including a first hydraulic pump and a first directional control valve connected to the first hydraulic pump and driving a cylinder.
a directional switching valve group, a second hydraulic pump, and a second directional switching valve group connected to the second hydraulic pump and including a second directional switching valve for merging; By operating the directional switching valve, the hydraulic machine is configured to combine the pressure oil of the first hydraulic pump and the pressure oil of the second hydraulic pump and supply the mixture to the cylinder via the first directional switching valve. In the hydraulic circuit, a conduit connecting an upstream side of the first directional control valve and an upstream side of the second directional control valve, one boat located downstream of the first directional control valve, a pipe connecting one boat located downstream of the second directional switching valve to the bottom side of the cylinder; and another boat located downstream of the first directional switching valve and the rod side of the cylinder. A hydraulic circuit for a hydraulic machine, characterized in that it is provided with a conduit that communicates with the hydraulic circuit.