JP2004245262A - Hydraulic circuit for working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive easy-to-operate hydraulic circuit for a working machine that can correspond to the flow requirements of various attachments with the combination of one pump, or confluence of two pumps or three pumps of three pieces of pumps by combining control valves and existing pumps provided in the working machine. <P>SOLUTION: Through the control of an attachment valve 6a, a first junction valve 6e, and a second junction valve 12b by a selective means 36, one from among the flow from a first pump 2, the confluence flow from the first pump and a second pump 4, and the confluence flow from the first pump, the second pump and a third pump 10 is selected and fed to a working oil supply port 16. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydraulic circuit of a working machine, and more particularly, to a hydraulic circuit suitable for a working machine equipped with various hydraulically operated working devices.
[0002]
[Prior art]
In a work machine, for example, a hydraulic shovel, which is a typical example thereof, various attachments, which are hydraulically operated working devices, are attached simultaneously or exchanged according to the form of work. To this end, hydraulic pumps are provided in the work machine so as to be able to supply different required hydraulic oil amounts of the hydraulic actuators of these attachments together with the machine body.
[0003]
As a method of responding to the required hydraulic oil amount of various actuators,
(1) Provide multiple pumps and drain unused pumps:
For example, when a large flow rate is required, the hydraulic oil of two pumps is used, and when a small flow rate is required, only the hydraulic oil of one pump is used and the hydraulic oil of the other pump is drained (for example, see Patent Document 1). .
[0004]
(2) Provide a dedicated pump for each attachment:
For example, a dedicated pump corresponding to each attachment is attached to a drive source such as an engine.
[0005]
(3) Use a large displacement pump:
Using a large-sized variable displacement pump, it is supplied by adjusting the flow rate and diverting according to the attachment requirements.
[0006]
As an example of an attachment, for example, when a hydraulic excavator is used for forestry work, a grapple that grips and collects wood with hydraulic pressure, a hydraulic winch that collects with a cable, a hydraulic winch that removes timber, cutting off timber, cutting off oil, etc. And the like. The required amount of hydraulic oil depends on these attachments, and requires one pump flow rate when using a grapple, two pump flow rates when using a winch, and three pump flow rates when using a processor. In this case, the hydraulic oils from the three pumps are combined or separated by appropriately using a manual switching valve, an electromagnetic switching valve, or the like.
[0007]
[Patent Document 1]
JP-A-2002-4341 (FIGS. 1 and 4)
[0008]
[Problems to be solved by the invention]
Therefore, the conventional working machine of the above-described embodiment has the following problems to be solved.
[0009]
(1) It is troublesome to switch the combination of pumps:
When a plurality of pumps are provided, the combination of the pump merging and the switching operation thereof must be performed for each of the plurality of attachments. For example, there is a configuration in which a rocker switch is provided on a console at the driver's seat to enable a combination switching operation. However, it is troublesome to operate each time by releasing the hand from the operation lever of the attachment, resulting in poor work efficiency.
[0010]
(2) The cost of the working machine increases:
When a dedicated pump is provided for each attachment, a dedicated driving device, a piping device, and a control valve device are required in addition to the pump, and the cost of the working machine is increased. Further, it is difficult to obtain a large-capacity variable displacement pump, and the cost is high.
[0011]
The present invention has been made in view of the above facts, and a technical problem thereof is that three pumps are combined into one pump, two pumps, or three pumps by a combination of an existing pump and a control valve provided in a work machine. It is an object of the present invention to provide a hydraulic circuit for a working machine which can cope with the required flow rates of various attachments, can easily perform a switching operation, and is inexpensive.
[0012]
[Means for Solving the Problems]
The invention described in claim 1 includes a first pump, a second pump, and a main circuit that includes a control valve that controls the flow of hydraulic oil and controls a machine body and a working arm attached to the machine body; Including a control valve for controlling the flow of the hydraulic oil and a sub-circuit for controlling a soil discharging device attached to the fuselage,
The control valve of the main circuit includes an attachment valve that controls and supplies hydraulic oil of the first pump to a hydraulic oil supply port to an attachment, which is a working device attached to the machine body and / or a working arm, and an inlet port of the attachment valve. A first merging valve for controlling and merging the hydraulic oil of the second pump,
The control valve of the sub-circuit has a second joining valve that controls and joins the working oil of the third pump to the working oil supply port,
Comprising a selection means, the hydraulic oil supply port,
(1) a first connection for controlling the attachment valve to supply hydraulic oil for the first pump;
(2) a second connection for controlling the attachment valve and the first junction valve to supply hydraulic oil for the first pump and the second pump;
(3) a third connection for controlling the attachment valve, the first merging valve, and the second merging valve to supply hydraulic oil for the first pump, the second pump, and the third pump;
The hydraulic circuit of the working machine is characterized by selecting any one of the following.
[0013]
Then, a total of three pumps, that is, a pair of pumps for controlling the body and a working arm attached to the body and a pump for controlling the earth removal device attached to the body, are selected by the selecting means into one pump, two pumps, and three pumps. To easily select the combination.
[0014]
According to a second aspect of the present invention, in the hydraulic circuit for a work machine according to the first aspect, the selection unit includes a first and second connection selection unit that selects a first connection or a second connection, and a third connection. And third connection selecting means for selecting.
[0015]
In addition, it is possible to easily select the relatively frequently used one pump and two pump merging.
[0016]
According to a third aspect of the present invention, in the hydraulic circuit for a working machine according to the second aspect, the first and second connection selection means include an operation pedal for operating the attachment valve and the first junction valve, and the third connection selection means. Has an electric switch for operating the attachment valve, the first junction valve, and the second junction valve.
[0017]
In order not to disturb the operation of the attachment, the selection of the combination of the one pump and the two pumps can be selected by the pedal, and the selection of the combination of the three pumps, which are relatively infrequently used, can be selected by the electric switch.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a hydraulic circuit of a working machine constituted according to the present invention will be described in more detail with reference to the accompanying drawings and FIG. 1, which illustrate a preferred embodiment of a hydraulic shovel as a typical working machine.
[0019]
A well-known hydraulic excavator includes a pair of pumps, a first pump 2, a second pump 4, and a control valve group 6 including a plurality of control valves for controlling the flow of hydraulic oil. A main circuit 8 for controlling the arm, a sub-circuit 14 for controlling the earth-discharge device mounted on the fuselage, including a third pump 10 and a control valve group 12 including a plurality of control valves for controlling the flow of hydraulic oil. have. Further, a hydraulic oil supply port 16 for supplying hydraulic oil to attachments, which are various working devices, is provided.
[0020]
The control valve group 6 is connected to the first pump 2 and has an attachment valve 6a for supplying and controlling hydraulic oil to a hydraulic oil supply port 16, a traveling control valve 6b for supplying and controlling a traveling device, and a boom for supplying and controlling a boom cylinder 18. A control valve 6c, a bucket control valve 6d for controlling the supply to the bucket cylinder, and a first merging valve 6e for controlling the hydraulic oil of the second pump 4 and selectively merging it with the boom cylinder 18 or the hydraulic oil supply port 16. I have. When these valves are not operated, the hydraulic oil of the first pump 2 flows to the tank 20 through the neutral flow paths of the travel control valve 6b, the attachment valve 6a, the boom control valve 6c, and the bucket control valve 6d.
[0021]
The control valve group 6 is further connected to the second pump 4 to control the supply of the operating oil to the traveling device, to a traveling control valve 6f, to a supply control to the upper revolving unit pivot motor, and to a supply control to the arm cylinder. It has an arm control valve 6h. When these valves are not operated, the hydraulic oil of the second pump 4 flows to the tank 20 through the neutral flow paths of the traveling control valve 6f, the turning control valve 6g, the arm control valve 6h, and the first merging valve 6e.
[0022]
The above-mentioned valves of the control valve group 6 are formed by an open center type three-position valve operated by pilot oil.
[0023]
The control valve group 12 of the sub-circuit 14 is connected to the third pump 10 and selectively joins the operating oil to the blade control valve 12 a and the operating oil supply port 16 for controlling the supply of the operating oil to the blade vertical cylinder of the earth removal device. It has a 2 merging valve 12b and an additional control valve 12c for blades. When these valves are not operated, the hydraulic oil of the third pump 10 flows to the tank 20 through the respective neutral flow paths. The above-mentioned valves of the control valve group 12 are also formed by open center three-position valves operated by pilot oil.
[0024]
Even if the attachment control valve 6a supplies the pilot oil to one of the operation ports A or the other operation port B to perform the switching operation, the hydraulic oil of the respective outlet side cylinder ports passes through the check valves 17 and 17, respectively. And is connected to the hydraulic oil supply port 16. An oil passage 24 connected to the first pump 2 is connected to the inlet port 22 of the working oil closed at the neutral position of the attachment control valve 6a via a check valve, and the oil connected to the second pump 4 The line 26 is connected via a check valve.
[0025]
The first merging valve 6e is known as a boom merging valve, and the outlet port closed at the neutral position is connected to an oil passage 30 connected to the head side of the boom cylinder 18 of the boom control valve 6c by an oil passage 28. . The second pump 4 is connected to the inlet port closed at the neutral position of the first junction valve 6e by an oil passage 32 via a check valve. When the pilot oil for switching the boom control valve 6c to supply the hydraulic oil to the oil passage 30 is diverted to one operation port D of the first junction valve 6e and supplied, the hydraulic oil of the second pump 4 is supplied to the oil passage 32, The oil flows into the oil passage 30 via the oil passage 28 and is supplied to the head side of the boom cylinder 18. When the pilot oil is supplied to the other operation port C, the inlet port and the outlet port of the first junction valve 6e are all closed.
[0026]
The second merging valve 12b has one outlet side cylinder port connected to the hydraulic oil supply port 16 by an oil passage 34. When the pilot oil is supplied to the operation port E, the operating oil of the third pump 10 flows through the oil passage 34.
[0027]
Therefore, by selectively switching the attachment valve 6a, the first junction valve 6e, and the second junction valve 12b, the first connection for supplying the hydraulic oil of the first pump 2 to the hydraulic oil supply port 16, Hydraulic circuits of a second connection for supplying hydraulic oil of the first pump 2 and the second pump 4 and a third connection for supplying hydraulic oil of the first pump 2, the second pump 4, and the third pump 10 are respectively formed. . This selection is made by the selection means 36.
[0028]
The selecting means 36 includes, as first and second connection selecting means 38 for selecting the first connection or the second connection, a pair of proportional pressure reducing valves 38a and 38b for outputting pilot oil, and an operation pedal 38c for operating them. An electromagnetic switching valve 40a for switching and outputting pilot oil and an electric switch 40b for operating the switching valve are provided as third connection selecting means 40 for selecting the third connection. The operation of the operation pedal 38c operates the attachment valve 6a or the attachment valve 6a and the first junction valve 6e, and the operation of the electric switch 40b operates the attachment valve 6a, the first junction valve 6e, and the second junction valve 12b. .
[0029]
When the operation pedal 38c is not operated, the pilot oil is not output from any of the proportional pressure reducing valves 38a and 38b. When the operation pedal 38c is operated in the direction of arrow L about the fulcrum and one of the proportional pressure reducing valves 38a is operated, the pilot oil of the pilot hydraulic source 42 is supplied to the port A of the attachment valve 6a. When the other proportional pressure reducing valve 38b is operated by operating in the direction of arrow R, the pilot oil is supplied to the port B of the attachment valve 6a and the port C of the first merging valve 6e via the shuttle valve 44.
[0030]
When the electric switch 40b is off, the electromagnetic switching valve 40a is not operated and no pilot oil is output. When the electric switch 40b is turned on and the electromagnetic switching valve 40a is operated, the pilot oil of the pilot hydraulic pressure source 42 receives the port E of the second junction valve 12b, the port B of the attachment valve 6a via the shuttle valve 44, and the port B of the first junction valve 6e. It is supplied to port C.
[0031]
Therefore, when the operation pedal 38c is operated to the one L side, the attachment control valve 6a is switched by supplying the pilot oil to the operation port A and the hydraulic oil of the first pump 2 is supplied to the hydraulic oil supply port 16. One connection hydraulic circuit is formed.
[0032]
When the operation pedal 38c is operated to the other R side, the attachment control valve 6a is switched by supplying pilot oil to the operation port B, and the first junction valve 6e is switched by supplying pilot oil to the operation port C. A second connection is formed in which the hydraulic oil of the first pump 2 and the second pump 4 is supplied to the hydraulic oil supply port 16.
[0033]
When the electric switch 40b is operated and turned on without operating the operation pedal 38c, the attachment control valve 6a is connected to the operation port B, the first junction valve 6e is connected to the operation port C, and the second junction valve 12b is connected to the operation port E. The pilot oil is supplied and switched, and a third connection is formed in which the hydraulic oil of the first pump 2, the second pump 4, and the third pump 10 is supplied to the hydraulic oil supply port 16.
[0034]
The operation of the hydraulic circuit of the working machine as described above will be described.
[0035]
(1) Pump combination and switching operation are easy:
The combination and switching operation of the three pumps of the pump 2, the pump 4, and the pump 10 can be easily performed by one operation pedal 38c and one electric switch 40b. Therefore, it is not necessary to release the hand from the operation lever of the attachment to perform the merging switching operation, so that the operability of the attachment by the operator can be improved, fatigue can be avoided, and work efficiency can be improved. For example, when forestry work is performed by a hydraulic excavator, a grapple, in which the hydraulic fluid of one pump is favorable, a hydraulic winch, in which the hydraulic fluid of two pumps is favorable, and a processor in which the hydraulic fluid of three pumps is favorable, are used as attachments. , Can be operated efficiently.
[0036]
(2) The cost of the working machine can be reduced:
The first pump 2, the second pump 4, the third pump 10, and the first merging valve 6e, the second merging valve 12b, and the like may be existing ones provided in the working machine, so that remodeling is substantially unnecessary, The configuration is easy, and the cost of the working machine can be reduced.
[0037]
【The invention's effect】
According to the hydraulic circuit of the work machine configured according to the present invention, three pumps can be combined into one pump, or a combination of two pumps or three pumps, depending on a combination of existing pumps and control valves provided in the work machine. It is possible to provide a hydraulic circuit for a working machine that can cope with various attachment required flow rates, can easily perform a switching operation, and is inexpensive.
[Brief description of the drawings]
FIG. 1 is a hydraulic circuit diagram of a working machine configured according to the present invention.
[Explanation of symbols]
2: First pump 4: Second pump 6a: Attachment valve 6e: First junction valve 8: Main circuit 10: Third pump 12b: Second junction valve 14: Subcircuit 16: Hydraulic oil supply port 22: Inlet port 36 : Selection means 38: first and second connection selection means 38c: operation pedal 40: third connection selection means 40b: electric switch

Claims (3)

A main circuit including a first pump and a second pump and a control valve for controlling a flow of hydraulic oil thereof for controlling a body and a work arm attached to the body; a third pump and a control valve for controlling a flow of hydraulic oil thereof; And a sub-circuit for controlling an earth removal device attached to the fuselage,
The control valve of the main circuit includes an attachment valve that controls and supplies hydraulic oil of the first pump to a hydraulic oil supply port to an attachment, which is a working device attached to the machine body and / or a working arm, and an inlet port of the attachment valve. A first merging valve for controlling and merging the hydraulic oil of the second pump,
The control valve of the sub-circuit has a second joining valve that controls and joins the working oil of the third pump to the working oil supply port,
Comprising a selection means, the hydraulic oil supply port,
(1) a first connection for controlling the attachment valve to supply hydraulic oil for the first pump;
(2) a second connection for controlling the attachment valve and the first junction valve to supply hydraulic oil for the first pump and the second pump;
(3) a third connection for controlling the attachment valve, the first merging valve, and the second merging valve to supply hydraulic oil for the first pump, the second pump, and the third pump;
A hydraulic circuit for a working machine, characterized by selecting one of the following. The hydraulic pressure of a work machine according to claim 1, wherein the selection means includes first and second connection selection means for selecting a first connection or a second connection, and third connection selection means for selecting a third connection. circuit. The first and second connection selection means include an operation pedal for operating the attachment valve and the first junction valve, and the third connection selection means includes an electric switch for operating the attachment valve, the first junction valve, and the second junction valve. The hydraulic circuit for a working machine according to claim 2, wherein

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