JP2002038534A - Operation change-over control circuit for a plurality of actuators retrofitted in multi-functional excavator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operation change-over control circuit which controls a backup selector valve for a plurality of attachments retrofitted in an excavator, according to a pilot pressure system, and correctly controls the retrofitted attachments by a single operating lever without increasing the number of the operating levers, in spite of increased relationships between the operating levers and the selector valve due to employment of the pilot pressure system. SOLUTION: According to the operation change-over control circuit, a main control valve for the actuators retrofitted in the excavator is controlled according to the pilot pressure system, and the selector valve is interposed between the main control valve and the retrofitted actuators. The selector valve is controlled by a solenoid valve, whereby pressure oil fed from the main control valve is fed to the retrofitted actuators by switching connection to the actuators.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a relatively small and multifunctional excavating work having a shovel type front attachment and a blade used for excavating work and leveling work at a relatively small-scale construction site. The present invention relates to an operation switching control circuit for a plurality of actuators additionally provided for a new operation in addition to a standardly equipped actuator.

[0002]

2. Description of the Related Art In order to save labor and improve efficiency of excavation work and leveling work at a construction site of a relatively small scale, a relatively small-sized excavator-based front attachment and blades for performing excavation work and leveling work. Excavator is widely used.

Originally, a multifunctional excavator of this type is equipped with a boom hydraulic cylinder, an arm hydraulic cylinder, a bucket hydraulic cylinder, a traveling hydraulic motor, a turning hydraulic motor, and a blade as standard equipment. A main control valve for operating an elevating hydraulic cylinder and the like is provided as a standard inside a revolving round body in which an upper revolving body is rotatably provided on a lower traveling body. The standard equipped main control valve is operated by a pilot pressure system by an operation lever provided on the upper swing body and operated by an operator in a driver's seat. However, the traveling hydraulic motor is operated by a direct pulling system.

[0004] A spare main control valve is provided in advance with the main control valve provided as standard. This spare main control valve is equipped for use with any actuator. However, since the purpose of the spare main control valve is not clear in what kind of work it is used in advance, a pilot pressure system using an expensive pilot valve is not adopted, and the spare main control valve is provided on the upper rotating body. The operation lever is operated by an operator in a driver's seat, and is operated by a direct pulling method using mechanical means such as a link and a cable.

[0005] Next, a multifunctional excavator in which a blade attached to the front or rear of a multifunctional excavator equipped with a bucket and a blade can perform leveling work by a straight system is illustrated. FIG. 1 is a side view of a multifunctional excavator equipped with a blade 6 attached to a lower traveling body 1 and a bucket 12 attached to an upper revolving superstructure 2.

An upper revolving unit 2 is rotatably mounted on a lower traveling unit 1 via a revolving round body 3 provided on the lower traveling unit 1. A blade 6 for leveling the ground is mounted on a blade lifting frame 7 attached to the lower traveling body 1 in front of or behind the lower traveling body 1, and is provided on the upper rotating body 2. When the operator of the seat 4 operates the blade raising / lowering operation lever 18 attached to the operation lever stand 17, the main control valve is switched by the pilot pressure from a pilot valve (not shown), and the pressure oil is supplied to the blade raising / lowering hydraulic pressure. The oil is supplied to the cylinder 8, and the blade elevating frame 7 is moved up and down so as to be at an appropriate height by expansion and contraction of the blade elevating hydraulic cylinder 8, and the ground leveling work is performed by the blade 6.

[0007] A base end of a boom 10 is attached to the upper swing body 2 via a boom support 9 attached to the front thereof, and an arm 11 is attached to a tip end of the boom 10 and earth and sand is attached to a tip end thereof. A bucket 12 for performing excavation work and loading work is mounted. Reference numeral 13 denotes a boom elevating hydraulic cylinder for the boom 10;
Reference numeral 4 denotes an arm hydraulic cylinder for the arm 11, and reference numeral 15 denotes a bucket hydraulic cylinder for the bucket 12. The boom 10, the arm 11, and the bucket 1 are operated by operating the boom lifting hydraulic cylinder 13, the arm hydraulic cylinder 14, and the bucket hydraulic cylinder 15.
By bending and extending 2, the bucket 12 excavates the ground and carries the excavated earth and sand.

In order to perform these operations, the flow rate of the hydraulic pressure to the work attachment by the hydraulic pump can be adjusted by a throttle valve or the like, but the spare main control valve can be used for any operation. Since the purpose of use is unknown, it is set so that the maximum flow rate by driving the engine is supplied to the spare main control valve. Therefore, the maximum flow rate of the oil amount from the spare main control valve is also supplied to the additionally equipped actuator. Reference numeral 5 denotes a canopy, which is operated by an operator by operating the operation levers 16 and 18 to rotate the vehicle forward and backward, rotate the upper revolving unit 2, the boom elevating hydraulic cylinder 13, the arm hydraulic cylinder 14, the bucket hydraulic cylinder 15, Various operations are performed by expanding and contracting the blade lifting hydraulic cylinder 8.

[0009]

As described above, in the conventional multifunctional excavator, only one spare main control valve for performing one new operation in addition to the standard operation is prepared in advance. Although it is done, there is no room to add a main control valve to perform still another work, for example, such as tilt work and angle work on the blade, or instead of the bucket 12 It is difficult to install a new main control valve to perform another operation that requires two operations such as grasping and rotating an object with a fork, like a full swing type fork attached to the tip of the arm . In the case where two operations to be added are required in this way, in a direct drawing method using mechanical means such as a link or a cable, there is a means for switching the link, but in principle, one operation lever is used. Only one control valve can be operated.

Normally, the spare main control valve is set to have a maximum flow rate so that the maximum power can be exerted, and it is not known how the spare main control valve is used. And the spare main control valve is operated by direct pulling with the operating lever, so the stroke of the operating lever is fixed and the maximum flow rate is supplied. In the case of an additional attachment that does not require a flow rate, for example, a breaker, etc., the flow rate of the supplied pressure oil is too large, so that the engine operation lever is provided with a stopper function to control the flow rate by controlling the engine speed. There are many. Thus, the flow rate control to the additional attachment cannot be performed unless the stopper function is provided. Further, in a direct drawing method using mechanical means such as a link or a cable, it has been difficult to control the flow rate for this purpose.

In view of the above, the present invention has been made in view of the above-mentioned problems, and provides a supplementary main control valve for an attachment additionally provided for performing two operations by using a link or cable as in a conventional excavating machine. Instead of operating by a direct pulling method by mechanical means such as, etc., it is operated by a pilot pressure method, and with this pilot pressure method, it was one-to-one like a conventionally known multifunctional excavator. A multifunctional excavator in which the relationship between the control lever and the main control valve is controlled by one control lever to properly operate two or more additional attachments and also to control the flow rate to the additional attachments. It is an object of the present invention to provide an operation switching control circuit for a plurality of actuators additionally provided.

[0012]

SUMMARY OF THE INVENTION In order to achieve the above object, an invention according to claim 1 of the present invention is directed to a relatively small multifunctional excavator equipped with a shovel type front attachment and a blade. In addition to the standard-equipped actuators, the main control valves of a plurality of additional actuators are operated by a pilot pressure system, and a selector valve is interposed between the main control valve and the additional actuators. The selector valve switches the supply of the pressure oil from the main control valve to a plurality of actuators additionally provided by operating a solenoid valve.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. FIG.
It is a side view of a multifunctional excavator. FIG. 2 is a plan development view of the multifunctional excavator of the present invention, FIG. 3 is a circuit diagram of operation switching control of a plurality of additional actuators of the present invention, and FIG. FIG. 5 is an operation switching control circuit diagram of a plurality of actuators additionally provided in another embodiment, FIG. 5 is a schematic development view of a pilot valve operating lever of the present invention, and FIG. 6 is a stroke of the pilot valve of the present invention. FIG. 7 is a diagram showing the relationship between the stroke of the pilot valve for a plurality of actuators additionally equipped according to the present invention and the output secondary pressure.

Here, a multifunctional excavator having a bucket and a blade is provided with a tilt hydraulic cylinder 19 and an angle hydraulic cylinder 29 for performing tilt and angle operations on the blade 6 as an additional attachment. The configuration of the multifunctional excavator will be described. The multifunctional excavator of the present invention also has substantially the same configuration as the above-described conventional multifunctional excavator, and the upper excavator is provided with a swivel body 3 provided on the lower traveling unit 1. A revolving unit 2 is pivotably mounted, and a blade 6 for leveling the ground is provided in front of or behind the lower traveling unit 1.
Is mounted on the tip of a blade elevating frame 7 attached to the undercarriage 1, and the blade elevating frame 7 is swung up and down by a blade elevating hydraulic cylinder 8 to perform ground leveling work. I have.

A base end of a boom 10 is attached to the upper swing body 2 via a boom support 9 attached to the front of the upper swing body 2. An arm 11 is attached to a tip of the boom 10, and earth and sand is attached to a tip of the boom 10. A bucket 12 for performing excavation work and loading work is mounted, and the boom 10 is operated by operating the operation levers 16 and 16 for the hydraulic cylinders 13 for the boom elevating, the hydraulic cylinder for the arm 14 and the hydraulic cylinder 15 for the bucket. The arm 12 and the bucket 12 are bent to extend and excavate the ground and transport and load the excavated earth and sand.

Reference numeral 4 denotes a seat for an operator,
Reference numeral 5 is a canopy. Operation levers 16, 16, 1
8 is operated by the operator to move forward and backward, and the upper revolving unit 2 is rotated, the boom lifting hydraulic cylinder 13, the arm hydraulic cylinder 14, and the bucket hydraulic cylinder 1 are operated.
5. Hydraulic cylinder for running, turning operation, and raising / lowering blade 8
Various operations are performed by expanding and contracting the hydraulic cylinder 19 for blade tilt and the hydraulic cylinder 29 for blade angle.

The operating lever 18 attached to the operating lever stand 17 is provided with a pilot valve 13. The operating lever 18 can be operated by one lever and two levers. A cross bar is provided on each end of the cross bar 181, 182, 183, 184 by swinging the operation lever 18 in the front-rear direction or the left-right direction, as shown in FIG. , Pilot valve 362, pilot valve 363,
Press one of the pilot valves 364 to release the pilot valve 3
6 by switching the pilot valve 36, the main control valve 35 and the hydraulic cylinder 1 for tilting.
The selector valve 21 for switching between the hydraulic cylinder 9 and the angle hydraulic cylinder 29 is configured to be switched.

Next, an operation switching control circuit of a plurality of actuators additionally provided with the multifunctional excavator according to the present invention will be described with reference to FIG. 3. Reference numeral 72 denotes a hydraulic cylinder for an attachment requiring a full flow rate. Reference numerals 20 and 21 are a swivel joint and a selector valve, respectively. Each end 181 of a cross bar provided below the operation lever 18 attached to the operation lever stand 17,
Below 182, 183, 184, four pilot valves 361, 362, 363, 364 respectively correspond.

Reference numerals 31, 32 and 33 are hydraulic pumps. Pressure oil from the pump 31 is sent to a main control valve 34 operated by pilot pressure via an oil passage 42. The pressure oil from the main control valve 34 is
The oil is sent to the hydraulic cylinder for tilt 19 or the hydraulic cylinder for angle 29 via the swivel joint 20 and the selector valve 21 via the oil passages 43 and 44. Pressure oil from the pump 32 is sent to a main control valve 35 operated by pilot pressure via an oil passage 46. Then, the fluid is sent from the swivel joint 20 to the blade lifting / lowering hydraulic cylinder 72 via the oil passage 47 or the oil passage 48. The pump 33 is a pump for pilot pressure, is sent from an oil passage 51 to a solenoid valve 37 a, and is connected from a pilot oil passage 52 to a pilot port of the selector valve 21. On the other hand, the oil passage 53 branched from the oil passage 51 includes a pilot valve 361, a pilot 362, and a pilot valve 363.
Is sent to the pilot 364.

The pilot pressure oil from the pilot valves 361 and 362 is connected to the pilot ports at both ends of the main control valve 35. Pilot valve 3
Pilot pressure oil from 63 and pilot 364 is connected to pilot ports at both ends of main control valve 34. The oil passages 45 and 50 are oil passages to the tank 38. Reference numeral 39 denotes a power supply, and a switch 40
a, the relay 41a is closed and the solenoid valve 37 is closed.
a is switched.

I) Here, a hydraulic cylinder 72 which is an actuator of an attachment requiring a full flow of hydraulic oil from a hydraulic pump mounted on a multifunctional excavator.
The case of operating is described.

When the operation lever 18 attached to the operation lever stand 17 is operated in the direction a1 in FIG. 5 to contract the hydraulic cylinder 72, the end of the cross bar provided below the operation lever 18 181 presses the pilot valve 361. Then, the pilot pressure oil from the pilot pressure pump 33 is supplied to the pilot valve 361.
-Enter the pilot port of the main control valve 35 from the pilot oil passage 54, and switch the main control valve 35 to the C position.

Then, the pressure oil from the pump 32 is supplied to the oil passage 4
6 through the oil passage 48 and the swivel joint 20 according to the position of the main control valve 35, and the hydraulic cylinder 7
The hydraulic cylinder 72 contracts upon entering the rod side of FIG.

Conversely, when the hydraulic cylinder 72 is extended, when the operation lever 18 is operated in the direction a2 in FIG. 5, the end 182 of the cross bar provided below the operation lever 18 is moved to the pilot position. Depress valve 362. Then, the pilot pressure oil from the pilot pressure pump 33 is supplied to the pilot valve 362-pilot oil passage 55.
From the other pilot port of the main control valve 35, and switches the main control valve 35 to the a position.

Then, the pressure oil from the pump 32 is supplied to the oil passage 4
6 through the oil passage 47 and the swivel joint 20 according to the position of the main control valve 35 and the hydraulic cylinder 7
The hydraulic cylinder 72 is extended into the bottom side of 2. The main control valve 3 is provided in the pilot oil passages 54 and 55.
Since the secondary pressure is set so that the spool No. 5 is fully opened, the operation of expanding and contracting the hydraulic cylinder 72 can be performed according to the characteristic diagram shown by the line A in FIG.

II) Next, a case of operating an actuator additionally provided in a multifunctional excavator will be described. First, the operation of the tilt hydraulic cylinder 19 of the additionally provided actuator by operating only the pilot valve 36 will be described. When the operation lever 18 attached to the operation lever stand 17 is operated in the direction b1 in FIG. The end 183 of the cross bar provided below the lever 18 presses the pilot valve 363. Then, the pilot pressure oil from the pilot pressure pump 33 is supplied to the pilot oil passage 53-the pilot valve 363.
-Enter one pilot port of the main control valve 34 from the pilot oil passage 56, and switch the main control valve 34 to the A position.

Then, the pressure oil from the pump 31 is supplied from the position A of the main control valve 34 to the rod side of the hydraulic cylinder 19 for tilt through the oil passage 43, the swivel joint 20 and the position B of the selector valve 21. The hydraulic cylinder 19 for tilt is contracted, and the blade 6 is inclined with the contraction of the hydraulic cylinder 19 for tilt,
Form a laterally inclined excavation surface. In the case of forming an excavation surface inclined to the opposite side, when the operation lever 18 is operated in the direction b2 of FIG. 5, the end 184 of the cross bar provided below the operation lever 18 becomes This can be performed by pressing the valve 364 to switch the main control valve 34 to the position C. At this time, the stroke of the spool of the main control valve 34 is limited in the pilot oil passages 56 and 57 by reducing the pressure of the secondary pressure characteristic of the line B as shown in the secondary pressure characteristic diagram of FIG.
The flow rate is controlled. Therefore, the tilt hydraulic cylinder 19 can relatively slowly expand and contract without being driven by the maximum flow rate from the hydraulic pump.

III) Next, the operation of the angle hydraulic cylinder 29 additionally provided will be described. When the switch 40a in the driver's seat is turned on to operate the angle hydraulic cylinder 29, the switch 40 is turned on.
With the closing of a, the electricity from the power source 39 operates the relay 41a via the switch 40a to close the relay 41a. When the relay 41a is closed, the solenoid valve 37a is operated, the solenoid valve 37a is switched from the low position to the a position, and the pilot pressure oil from the pump 33 is supplied to the pilot oil passage 51, the a position of the solenoid valve 37a, and the pilot pressure. It enters the pilot port of the selector valve 21 via the oil passage 52, and switches the selector valve 21 from the B position to the A position.

When the switch 40a is turned on and the operation lever 18 attached to the operation lever stand 17 is operated in the direction b1 in FIG. 5, the end 183 of the cross bar provided below the operation lever 18 is moved to the pilot position. Valve 3
Press 63. Then, the pump 33 for pilot pressure
From the pilot oil passage 53-pilot valve 363-pilot oil passage 56 enters one pilot port of the main control valve 34, and switches the main control valve 34 to the a position.

Then, the pressure oil from the pump 31 is supplied from the position A of the main control valve 34 to the bottom side of the angle hydraulic cylinder 29 via the oil passage 43, the swivel joint 20 and the position A of the selector valve 21. The angle hydraulic cylinder 29 is extended, and with the extension, the left side of the blade 6 shown in FIG. 3 is protruded forward to incline. The soil is discharged to the side along the side surface inclined to the side. In order to discharge earth and sand on the opposite side, operating the operation lever 18 in the direction b2 in FIG.
The operation can be performed by switching the main control valve 34 to the position C by pressing the pilot valve 364 with the end 184 of the cross bar provided below the operation lever 18.

At this time, the stroke of the spool of the main control valve 34 is reduced in the pilot oil passages 56 and 57 by reducing the pressure of the secondary pressure characteristic of the line B as shown in the secondary pressure characteristic diagram of FIG. It restricts and controls the flow rate. For this reason, the hydraulic cylinder for tilt 19 or the hydraulic cylinder for angle 29 can be relatively slowly expanded and contracted without being operated and driven at the maximum flow rate from the hydraulic pump. For this reason, the hydraulic cylinder for tilt 19
Can perform relatively slowly expanding and contracting operation without being driven by the maximum flow rate from the hydraulic pump.

Next, as another embodiment of the present invention, a hydraulic cylinder 59, which is an actuator for a front attachment, is additionally provided as shown in FIG. The operation switching control circuit will be described. Reference numeral 72 denotes a hydraulic cylinder for an attachment requiring a full flow rate, and each end 181, 182, 183, 1 of a cross bar provided below the operation lever 18 attached to the operation lever stand 17.
Below the 84, four pilot valves 361, 362, 363, and 364 of the pilot valve 36 respectively correspond.

The pressure oil from the hydraulic pump 31 is sent through an oil passage 42 to a main control valve 34 operated by pilot pressure. The pressure oil from the main control valve 34 is sent from the selector valve 61 via the oil passages 43 and 44 to the tilt hydraulic cylinder 19 or the angle hydraulic cylinder 29 via the swivel joint 20 and the selector valve 21. The pressure oil from the main control valve 34 switched at 61 is connected to the rod-side and bottom-side ports of the hydraulic cylinder 59 via the oil passage 66 and the manual switching valve 60-oil passage 67. Pressure oil from the hydraulic pump 32 is sent to a main control valve 35 operated by pilot pressure via an oil passage 46. Then, the fluid is sent from the swivel joint 20 through the oil passage 47 or the oil passage 48 to the hydraulic cylinder 72 for attachment requiring a full flow rate.

The hydraulic pump 33 is a pump for pilot pressure and is an oil passage 51-solenoid valve 37c-solenoid valve 37
a-A pilot oil passage 52 is connected to a pilot port of the selector valve 21. On the other hand, the oil passage 53 branched from the oil passage 51 is sent to the pilot valve 361 and the pilot 362, and to the pilot valve 363 and the pilot 364. Further, the pressure oil from an oil passage 65 branched from the oil passage 51 is switched by a solenoid valve 37b, and is connected to a pilot port of the selector valve 61 via a pilot oil passage 71.

The solenoid valve 37b is connected to a power supply 39, a switch 40b, and a relay 41b. When the switch 40b is closed, the relay 41b is closed and the solenoid valve 37b is switched. The solenoid valve 37c includes a power supply 39, a switch 40b, and a relay 4
1b, and is connected to a relay 41 by closing a switch 40b similarly to the solenoid valve 37b.
b is closed and the solenoid valve 37c is switched.

The pilot pressure oil from the pilot valve 361 and the pilot pressure oil from the pilot 362 of the pilot valve 36 are connected to the pilot ports at both ends of the main control valve 35. Pilot pressure oil from the pilot valve 363 and the pilot 364 is connected to pilot ports at both ends of the main control valve 34. In addition, the oil passage 45, the oil passage 5
0 is an oil passage to the tank 38. Reference numeral 39 denotes a power supply, which closes the relay 41a by closing the switch 40a to switch the solenoid valve 37a. Reference numeral 58 denotes a pilot valve having two pilot valves 581 and 582, which is connected to a solenoid valve 37c through a pilot oil passage 73, and pressure oil from the hydraulic pump 33 is supplied by switching the solenoid valve 37c.

IIII) Here, FIG. 4 shows the case where the hydraulic cylinder 72, which is the actuator of the attachment that requires a full flow of hydraulic oil from the hydraulic pump mounted on the multifunctional excavator, is operated as described above.

As described above.

V) Next, FIG. 4 illustrates a case in which an actuator additionally provided to the multifunctional excavator is operated.

First, the case of operating the tilt hydraulic cylinder 19 of the additionally equipped actuator by operating only the pilot valve 36 will be described. The operation lever 18 attached to the operation lever stand 17 is moved to the position shown in FIG.
When operated in one direction, the end 183 of the cross bar provided below the operation lever 18 presses the pilot valve 363. Then, the pilot pressure oil from the pilot pressure pump 33 enters one of the pilot ports of the main control valve 34 from the pilot oil passage 53-the pilot valve 363-the pilot oil passage 56 via the shuttle valve 63, and the main control valve 34 Switch to position a.

Then, the pressure oil from the pump 31 flows from the position A of the main control valve 34 to the position A of the selector valve 61, the oil passage 43, the swivel joint 20 and the position B of the selector valve 21 to the hydraulic cylinder 19 for tilt. The hydraulic cylinder 19 for tilting is supplied to the rod side.
Is contracted, and the blade 6 is inclined with the contraction of the tilt hydraulic cylinder 19. When an excavation surface inclined to the opposite side is formed, the operation lever 18 is moved to the position shown in FIG.
When operated in the direction b2, the end 184 of the cross bar provided below the operation lever 18 is moved to the pilot valve 36.
This can be done by pressing 4 and entering the other pilot port of the main control valve 34 via the pilot oil passage 57-shuttle valve 64 and switching the main control valve 34 to the C position. At this time, the stroke of the spool of the main control valve 34 is limited in the pilot oil passages 56 and 57 by lowering the pressure of the secondary pressure characteristic along the line B in the secondary pressure characteristic diagram of FIG. Then, the flow rate is controlled. For this reason, the hydraulic cylinder for tilt 19 can perform the operation of expanding and contracting relatively slowly without being operated and driven at the maximum flow rate from the hydraulic pump.

VI) Next, referring to FIG. 4, the case of operating the additionally provided angle hydraulic cylinder 29 will be described. To operate the angle hydraulic cylinder 29, a switch 40a in the driver's seat is turned on. When the switch 40a is closed, the electricity from the power supply 39 is switched to the switch 4
Via 0a, the relay 41a is operated to close the relay 41a. By closing the relay 41a, the solenoid valve 37a
Is operated, the solenoid valve 37a is switched from the B position to the A position, and the pilot pressure oil from the pump 33 is supplied to the pilot oil passage 51-the A position of the solenoid valve 37c-the A position of the solenoid valve 37a-the pilot oil passage 52 Through the pilot port of the selector valve 21 to switch the selector valve 21 from the B position to the A position.

When the switch 40a is turned on and the operation lever 18 attached to the operation lever stand 17 is operated in the direction b1 in FIG. 5, the end 183 of the cross bar provided below the operation lever 18 is moved to the pilot position. Valve 3
Press 63. Then, the pump 33 for pilot pressure
From the pilot oil passage 51, the position of the solenoid valve 37c, the pilot oil passage 53, the pilot valve 363, the pilot oil passage 56, the shuttle valve 63, and enters one pilot port of the main control valve 34. The main control valve 34 is switched to the position A.

Then, the pressure oil from the pump 31 passes through the position A of the main control valve 34, the position A of the selector valve 61, the oil passage 43, the swivel joint 20, and the position A of the selector valve 21. Supplied to the bottom side, this angle hydraulic cylinder 2
9 is extended and the left side of the blade 6 shown in FIG. 3 is protruded forward and inclined with the extension, and the excavated earth and sand excavated by the blade 6 while moving forward is inclined to the side of the blade 6. The soil is discharged to the side along the surface. In order to discharge earth and sand on the opposite side, the operation lever 18 is moved to the position shown in FIG.
When operated in the direction b2, the end 184 of the cross bar provided below the operation lever 18 is moved to the pilot valve 36.
4 can be pressed to switch the main control valve 34 to the C position.

VII) Next, FIG. 4 shows a case where the hydraulic cylinder 59 additionally provided is extended. When the switch 40b is turned on in order to operate the hydraulic cylinder 59 additionally provided, the relay 41b is closed, and the solenoid valve 37 is closed by closing the relay 41b.
b is switched from the B position to the A position, and at the same time, 37c is also switched from the A position to the B position. Then, the pilot pressure oil from the hydraulic pump 33 is sent to the pilot oil passage 51-the added pilot valve 58 by switching the solenoid valve 37b to the low position.

At the same time, the pressure oil for pilot, which has been supplied to the pilot valve 36 through the oil passage 53, is cut off by switching the solenoid valve 37c to the low position. Is not supplied, so that the pilot valve 36 cannot be operated. Further, when the solenoid valve 37b is switched to the position A, the pilot pressure oil flows through the pilot oil passage 71 and enters the pilot port of the selector valve 61, and switches the selector valve 61 from the position A to the position B. The pilot pressure oil sent from the pilot oil passage 51 to the added pilot valve 58 is supplied to the pilot valve 582-pilot oil passage 70-shuttle valve 64-main control valve by operating the pilot valve 582 of the added pilot valve 58. It enters the pilot port 34 and switches the main control valve 34 from the B position to the C position.

Then, the pressure oil from the hydraulic pump 31 is sent to the port of the switching valve 60 from the oil passage 42-the position C of the main control valve 34-the position B of the selector valve 61, and from the driver's seat of the switching valve 60. Hydraulic cylinder 59 additionally provided by switching to position a by mechanical switching operation of
And the hydraulic cylinder 59 is extended. Since the pilot pressure secondary pressure characteristic of the added pilot valve 58 is the secondary pressure characteristic as shown in FIG. 7, the spool of the main control valve 34 is fully opened, and the total flow rate from the hydraulic pump 31 is added. Oil can be sent to the equipped hydraulic cylinder 59, and the extension operation can be performed quickly. Further, by switching the selector valve 61, an optimal flow rate can be supplied from the hydraulic pump 31 to the hydraulic cylinders 19 and 29 which are additional actuators for attachment.

VIII) A case in which the additionally provided hydraulic cylinder 59 is contracted will be described. In order to operate the hydraulic cylinder 59 additionally provided, the switch 40b is turned on in the same manner as in the above “VII)”, so that the pilot pressure oil for the pilot from the hydraulic pump 33 is added from the pilot valve 36 to the pilot valve 58. Switch to
By operating the pilot valve 581 of the added pilot valve 58, the selector valve 61 is switched, and further, by switching the switching valve 60 by a mechanical switching operation from the driver's seat, the hydraulic cylinder 59 can be contracted. .

As described above, when the additional hydraulic cylinder 59 is operated to expand and contract, the blade tilt / angle operation switching control circuit diagram shown in FIG. 3 includes a pilot valve 58 for switching the main control valve 34 and a pilot valve 58 for switching the main control valve 34. Selector valve 21 for switching between hydraulic cylinders 19 and 29, which are additional actuators for attachment, and hydraulic cylinder 59, which is additionally mounted, and pilot pressure oil from hydraulic pump 33 for pilot valve 36.
Switch 4 for switching from the above to the pilot valve 58
0b, a hydraulic cylinder 5 additionally provided by additionally providing a solenoid valve 37b and a solenoid valve 37c.
9 can be expanded and contracted.

As described above, according to the present invention, when there is only one spare main control valve and two additional actuators are provided, as in the case of a conventional excavating machine, a link and a cable are provided. In the direct pulling method by mechanical means, only one main control valve can be operated by one operating lever, but in the present invention, the main control valve is operated by the pilot pressure method and provided in a circuit from this main control valve. By electrically switching the spare selector valve provided, two additional actuators, such as the above-described switching between the tilt hydraulic cylinder and the angle hydraulic cylinder, can be appropriately selected and used.

[0051]

As described above, according to the present invention, when there is only one spare main control valve and there are two actuators to be additionally provided, as in the case of a conventional excavating machine, a link or a control valve is provided. In the direct pulling method using a mechanical means such as a cable, only one main control valve can be operated with one operating lever.
By operating the main control valve by the pilot pressure system and electrically switching the spare selector valve provided in the circuit from this main control valve,
As described above, two additional actuators, such as switching between the tilt hydraulic cylinder and the angle hydraulic cylinder, can be appropriately selected and used.

[Brief description of the drawings]

FIG. 1 is a side view of a multifunctional excavator,

FIG. 2 is a plan development view of the multifunctional excavator of the present invention,

FIG. 3 is a circuit diagram of a tilt / angle operation switching control circuit of the blade according to the present invention;

FIG. 4 is an operation switching control circuit diagram of a plurality of actuators additionally provided according to another embodiment of the present invention;

FIG. 5 is a schematic development view of a pilot valve operation lever of the present invention,

FIG. 6 is a relationship diagram between a stroke of a pilot valve operating lever and an output secondary pressure according to the present invention;

FIG. 7 is a diagram showing a relationship between a stroke of a pilot valve for a plurality of actuators additionally equipped according to the present invention and an output secondary pressure.

[Explanation of symbols]

1 lower traveling structure, 2 upper revolving structure, 3 revolving round body,
4 seats, 5 canopy, 6 blades, 7
Blade lifting frame, 8 blade lifting hydraulic cylinder, 9 boom support, 10 boom, 11 arm, 12 bucket, 13 boom lifting hydraulic cylinder, 14 arm hydraulic cylinder, 15 bucket hydraulic cylinder, 16 operating lever, 17
Operating lever stand, 18 pilot valve operating lever,
19 Hydraulic cylinder for tilt, 20 Swivel joint, 21 Selector valve, 22 Hydraulic cylinder mounting member for elevating blade, 23 Machine stand, 24 Frame mounting bracket, 25 Mounting bracket, 26
Bolt, 27 mounting bracket, 28 mounting bracket, 29 angle hydraulic cylinder, 30
Hydraulic cylinder rod for angle, 31 pump 1,
32 Pump 2, 33 Pump 3, 34 Main control valve, 35 Main control valve, 36
Pilot valve, 361 Pilot valve, 362 Pilot valve, 363 Pilot valve, 364 Pilot valve, 37a, 37b, 37c Solenoid valve, 3
8 tank, 39 power supply, 40a, 40b switch, 41a, 41b relay, 42, 43, 44, 4
5, 46, 47, 48, 49, 50, 51 Oilway, 52
Pilot oil passage, 53 oil passage, 54 pilot oil passage, 55 pilot oil passage, 56 pilot oil passage, 57 pilot oil passage, 58 pilot valve,
581 pilot valve, 582 pilot valve, 59
Hydraulic cylinder, 60 switching valve, 61 selector valve, 62 electric circuit, 63 shuttle valve, 64 shuttle valve, 65, 66, 67, 68 oil path, 69, 7
0, 71 pilot oilway, 72 hydraulic cylinder,
73, 74, 75, 76 Pilot oilway, G ground.

Claims (1)

[Claims] In a relatively small multifunctional excavator having a shovel-based front attachment and a blade, a main control valve of a plurality of actuators additionally provided in addition to an actuator provided as standard is provided with a pilot pressure. Operated by the system, a selector valve was interposed between the main control valve and a plurality of actuators additionally provided, and the selector valve was additionally equipped with pressure oil from the main control valve by operating a solenoid valve. An operation switching control circuit for a plurality of actuators additionally provided with a multifunctional excavator, wherein the plurality of actuators are supplied by being switched to a plurality of actuators.