JP3964800B2 - Hydraulic circuit of work machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic circuit for a work machine, and more particularly to a hydraulic circuit suitable for a work machine equipped with various hydraulically operated work devices.
[0002]
[Prior art]
Various attachments, which are hydraulically-operated working devices, are attached to a working machine, for example, a hydraulic excavator as a typical example thereof, at the same time or exchanged depending on a work form. For this purpose, the working machine is provided with a hydraulic pump 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 to meet 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 fluid of two pumps is used. When a small flow rate is required, only the hydraulic fluid of one pump is used and the hydraulic fluid of the other pump is drained (see, for example, 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 capacity variable displacement pump:
A large variable displacement pump is used to adjust the flow rate according to the demand of the attachment, and supply it by diversion.
[0006]
For example, when using a hydraulic excavator for forestry work, for example, a grapple that grips and collects wood with oil pressure, a hydraulic winch that collects wood with a cable, wood debranching, chopping, etc. It is equipped with a processor etc. The amount of hydraulic oil required depends on these attachments, and requires one pump flow when using grapples, two pumps when using winches, and three pumps when using processors. In this case, the hydraulic oil from the three pumps is used as appropriate, such as a manual switching valve and an electromagnetic switching valve, and merged or branched.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-4341 (FIGS. 1 and 4)
[0008]
[Problems to be solved by the invention]
Therefore, the conventional work machine having the form as described above has the following problems to be solved.
[0009]
(1) The pump combination switching operation is troublesome:
When there are a plurality of pumps, it is necessary to perform a combination of pump merging and a switching operation thereof in accordance with a plurality of attachments each time. For example, there is a driver's console provided with a rocker switch so that a combination switching operation can be performed. However, it is troublesome to operate by manually releasing the operation lever of the attachment each time, and the work efficiency is also deteriorated.
[0010]
(2) The cost of the work machine increases:
When a dedicated pump is provided for each attachment, a dedicated drive device, piping device, and control valve device are required in addition to the pump, which increases the cost of the work machine. In addition, large capacity variable displacement pumps are difficult to obtain and costly.
[0011]
The present invention has been made in view of the above-mentioned facts, and its technical problem is that three pumps are combined into one pump, or two pumps or three pumps are combined according to a combination of existing pumps and control valves provided in a work machine. Thus, it is possible to provide a hydraulic circuit for a work machine that can cope with the required flow rate of various attachments, that is easy to switch and is low in cost.
[0012]
[Means for Solving the Problems]
The invention described in claim 1 includes a first circuit, a second pump, and a main circuit that includes a control valve that controls a flow of hydraulic fluid thereof, and controls a machine body and a work arm attached to the machine body, a third pump, Including a control valve for controlling the flow of the hydraulic oil, and a sub-circuit for controlling the earth removing device attached to the airframe,
The control valve of the main circuit includes an attachment valve for controlling and supplying the hydraulic oil of the first pump to the hydraulic oil supply port to the attachment which is a working device attached to the airframe and / or the work arm, and the 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 merging valve for controlling and merging the hydraulic oil of the third pump at the hydraulic oil supply port,
Selecting means, and the hydraulic oil supply port,
(1) a first connection for controlling the attachment valve and supplying hydraulic fluid of the first pump;
(2) a second connection for controlling the attachment valve and the first merging 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 of the first pump, the second pump, and the third pump;
Select one of the
The selection means includes first and second connection selection means for selecting the first connection or the second connection, and third connection selection means for selecting the third connection,
The first second connection selection means includes an operation pedal for operating the attachment valve and the first merging valve, and the third connection selection means includes an electrical switch for operating the attachment valve, the first merging valve, and the second merging valve. It is the hydraulic circuit of the working machine characterized by this.
[0013]
Then, a total of three pumps, that is, a pair of pumps for controlling the machine body and a work arm attached to the machine body, and a pump for controlling the earth removing device attached to the machine body are selected by a selection means, one pump, two pumps, and three pumps. 1 pump and 2 pumps so that the combination of 1 pump and 2 pumps, which are relatively frequently used, can be easily selected and the operation of the attachment is not disturbed. The switching selection of the merging is made possible by the pedal, and the switching selection of the three-pump merging which is relatively infrequently used is made by the electric switch .
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a hydraulic circuit of a working machine configured according to the present invention will be described in more detail with reference to the accompanying drawings and FIG. 1 illustrating a preferred embodiment of a hydraulic excavator that is 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 fluid thereof, and a work attached to the airframe and the airframe. A main circuit 8 for controlling the arm, and a sub-circuit 14 for controlling a soil removal device provided with a control valve group 12 including a plurality of control valves for controlling the flow of the third pump 10 and its hydraulic oil and attached to the machine body; have. Moreover, the hydraulic oil supply port 16 for supplying hydraulic oil to the attachment which is various working apparatuses is provided.
[0020]
The control valve group 6 is connected to the first pump 2, an attachment valve 6 a for controlling supply of hydraulic oil to the hydraulic oil supply port 16, a travel control valve 6 b for controlling supply to the traveling device, and a boom for controlling supply to the boom cylinder 18. A control valve 6c, a bucket control valve 6d that controls supply to the bucket cylinder, and a first merging valve 6e that controls and selectively merges the hydraulic oil of the second pump 4 to the boom cylinder 18 or the hydraulic oil supply port 16. Yes. When these valves are not operated, the hydraulic fluid 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 hydraulic oil to the traveling device, the traveling control valve 6f for controlling the supply of the hydraulic oil to the upper swing body swinging motor, and the arm cylinder. An arm control valve 6h is provided. 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 travel control valve 6f, the swing control valve 6g, the arm control valve 6h, and the first merging valve 6e.
[0022]
The above-described 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 to selectively join the hydraulic oil to the blade control valve 12a and the hydraulic oil supply port 16 for supplying and controlling the hydraulic oil to the blade upper and lower cylinders of the earthing device. 2 merging valve 12b and blade additional control valve 12c. 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-described valves of the control valve group 12 are also formed by open center type three-position valves operated by pilot oil.
[0024]
Regardless of whether the attachment control valve 6a is switched by supplying pilot oil to one of the operation ports A or B, the hydraulic oil in each outlet side cylinder port passes through the check valves 17 and 17, respectively. The hydraulic oil supply port 16 is connected. In addition, an oil passage 24 connected to the first pump 2 is connected to the hydraulic oil inlet port 22 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 path 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 in 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 by an oil passage 32 through a check valve to the inlet port closed at the neutral position of the first merging valve 6e. When the pilot oil for switching the boom control valve 6c to supply hydraulic oil to the oil passage 30 is supplied to one operation port D of the first merging valve 6e, the hydraulic oil of the second pump 4 is supplied to the oil passage 32, The oil flows to the oil passage 30 via the oil passage 28 and is supplied to the head side of the boom cylinder 18. When pilot oil is supplied to the other operation port C, the inlet port and the outlet port of the first merging valve 6e are all closed.
[0026]
One outlet side cylinder port of the second merging valve 12 b is connected to the hydraulic oil supply port 16 through an oil passage 34. When pilot oil is supplied to the operation port E, the hydraulic oil of the third pump 10 flows into the oil passage 34.
[0027]
Therefore, the first connection for supplying the hydraulic oil of the first pump 2 to the hydraulic oil supply port 16 by selectively switching the attachment valve 6a, the first merging valve 6e, and the second merging valve 12b. A second connection for supplying hydraulic oil for the first pump 2 and the second pump 4, and a third connection for supplying hydraulic oil for the first pump 2, the second pump 4, and the third pump 10 are formed. . This selection is performed by the selection means 36.
[0028]
The selection means 36 includes a pair of proportional pressure reducing valves 38a and 38b for outputting pilot oil, and an operation pedal 38c for operating them as first and second connection selection means 38 for selecting the first connection or the second connection, As the third connection selection means 40 for selecting the third connection, an electromagnetic switching valve 40a for switching and outputting pilot oil and an electric switch 40b for operating the same are provided. The attachment valve 6a or the attachment valve 6a and the first merging valve 6e are operated by operating the operation pedal 38c, and the attachment valve 6a, the first merging valve 6e, and the second merging valve 12b are operated by operating the electric switch 40b. .
[0029]
When the operation pedal 38c is not operated, pilot oil is not output from any of the proportional pressure reducing valves 38a and 38b. When the operation pedal 38c is operated around the fulcrum in the direction of the arrow L and one proportional pressure reducing valve 38a is operated, the pilot oil from the pilot hydraulic power source 42 is supplied to the port A of the attachment valve 6a. When the other proportional pressure reducing valve 38b is operated in the direction of the 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 electrical switch 40b is off, the electromagnetic switching valve 40a is not operated and pilot oil is not output. When the electric switch 40b is turned on and the electromagnetic switching valve 40a is operated, the pilot oil of the pilot hydraulic power source 42 is supplied to the port E of the second merging valve 12b and further to the port B of the attachment valve 6a and the first merging valve 6e via the shuttle valve 44. Supplied to port C.
[0031]
Therefore, when the operation pedal 38c is operated to one L side, the attachment control valve 6a is switched by supplying 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. A 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 merging 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 merging valve 6e is connected to the operation port C, and the second merging valve 12b is connected to the operation port E. Pilot oil is supplied and switched, and a third connection is formed in which hydraulic oil of the first pump 2, second pump 4, and 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:
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 can be improved by the operator, fatigue can be avoided, and the working efficiency can be improved. For example, when forestry work is performed with a hydraulic excavator, a grapple with convenient hydraulic fluid for one pump is attached as an attachment, a hydraulic winch with favorable hydraulic fluid for two pumps, and a processor with convenient hydraulic fluid for three pumps. Can be operated efficiently.
[0036]
(2) The cost of the work machine can be reduced:
Since the first pump 2, the second pump 4, the third pump 10, the first merging valve 6e, the second merging valve 12b, etc. may be existing ones provided in the work machine, no modification is substantially required. The configuration is easy and the cost of the work 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 with one pump, or a combination of two pumps or three pumps, by combining existing pumps and control valves provided in the work machine. It is possible to provide a hydraulic circuit for a work machine that can cope with the required flow rate of various attachments, that is easy to switch, and that is low in cost.
[Brief description of the drawings]
FIG. 1 is a hydraulic circuit diagram of a work machine configured according to the present invention.
[Explanation of symbols]
2: First pump 4: Second pump 6a: Attachment valve 6e: First merging valve 8: Main circuit 10: Third pump 12b: Second merging valve 14: Sub circuit 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: electrical switch

Claims (1)

A main circuit for controlling the machine body and a work arm attached to the machine body including a control valve for controlling the flow of the first pump and the second pump and the hydraulic oil thereof, and a control valve for controlling the flow of the third pump and the hydraulic oil thereof And a sub-circuit for controlling the earth removing device attached to the airframe,
The control valve of the main circuit includes an attachment valve for controlling and supplying the hydraulic oil of the first pump to the hydraulic oil supply port to the attachment which is a working device attached to the airframe and / or the work arm, and the 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 merging valve for controlling and merging the hydraulic oil of the third pump at the hydraulic oil supply port,
Selecting means, and the hydraulic oil supply port,
(1) a first connection for controlling the attachment valve and supplying hydraulic fluid of the first pump;
(2) a second connection for controlling the attachment valve and the first merging 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 of the first pump, the second pump, and the third pump;
Select one of the
The selection means includes first and second connection selection means for selecting the first connection or the second connection, and third connection selection means for selecting the third connection,
The first second connection selection means includes an operation pedal for operating the attachment valve and the first merging valve, and the third connection selection means includes an electrical switch for operating the attachment valve, the first merging valve, and the second merging valve. are, the hydraulic circuit of the working machine, characterized in that.

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