JPH0886184A - Hydraulic circuit of pile driver - Google Patents

Abstract

PURPOSE: To suitably keep the edge tip load of an excavating member by disposing a variable relief valve in a pipe line for connecting a pipe line, which serves as the inlet side of a hydraulic motor when an elevating member is lowered, to an oil pressure tank, and setting the oil pressure in an operator cab. CONSTITUTION: In a pipe driver adapted to elevate an elevating member suspending an excavating member fitted to a reamer by driving a hydraulic motor 14 in rotation, pipe lines 20a, 20b are provided for connecting the hydraulic motor 14 to an oil hydraulic pump 10 for supplying oil pressure through a directional switching valve 12. A variable relief valve 22 is disposed in a connecting path 21 for connecting the pipe line 20a which serves as the inlet side of the hydraulic motor 14 when the elevating member is lowered and the oil pressure tank to each other, and oil pressure is set by an operating member provided in an operator cab. When the descending speed of an auger screw is excessively high, the preset pressure of the variable relief valve 22 is reduced to decrease the descending speed and lower the edge tip load. After the edge tip load is set to a suitable value, the edge tip load is kept within a suitable range only by holding an operating lever on the descend side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit for adjusting the thrust of an excavating member (for example, earth auger) of a pile driver.

[0002]

2. Description of the Related Art FIG. 2 shows the overall construction of a pile driver. A leader 4 is attached to the front surface of the pile driver main body 1 by a front bracket 2 and a back stay 3. An elevating member 5 is attached to the reader 4 so as to be vertically movable, and an auger screw 6 is hung at the lower end thereof. As shown in FIG. 3, a chain 7 is fixed to the leader 4 in a vertically stretched state, and the chain 7 and a pair of sprockets 8 attached to the elevating member 5 mesh with each other. Therefore,
When the sprocket 8 is rotated by the hydraulic motor built in the lifting member 5, the lifting member 5 moves up and down together with the auger screw 6. Reference numeral 9 is an earth auger drive device that rotates the auger screw 6 and is integral with the elevating member 5.

FIG. 4 shows a hydraulic circuit for rotating the sprocket 8 and the auger screw 5 described above.
Reference numerals 0 and 11 are hydraulic pumps, 12 and 13 are hydraulic pilot type directional valves, 14 is a hydraulic motor for rotating the sprocket 8, and 15 is a hydraulic motor for rotating the auger screw 5. The hydraulic motor 14 is arranged in the lifting member 5 of FIG. 3, and the hydraulic motor 15 is arranged in the earth auger drive device 9. Pilot operated valves 16 and 17 for instructing switching of the direction switching valves 12 and 13 are provided in the operator's cab. The pilot pressure supply portion for these operating valves 16 and 17 is not shown. When the operating lever 16a of the pilot operating valve 16 is operated from the neutral position to either the ascending direction or the descending direction, the direction switching valve 12 switches from the neutral position to the A position or the B position according to the operating direction, and the hydraulic motor 14 Rotates in a direction corresponding to the operating direction of the operating lever 16a, and the elevating member 5 moves up or down together with the auger screw 6. The direction switching valve 12 is for adjusting the thrust and speed of the auger screw 6,
The continuous control type is such that the flow rate increases as the operation amount from the neutral position of the operation lever 16a increases. Direction switching valve 12
When is switched to the A position side, the auger screw 6 descends. When the operation lever 17a of the pilot operation valve 17 is operated, the direction switching valve 13 is switched according to the operation direction and the hydraulic motor 15 is rotated. Reference numerals 18 and 19 are relief valves that limit the maximum discharge pressure of the hydraulic pumps 10 and 11.

When excavating a hole for burying a pile with the above-described pile driver, while operating the operation lever 17a to rotate the auger screw 6, the operation lever 16a is operated to lower the elevating member 5. , Push the auger screw 6 into the ground. At this time, the driver of the pile driver must prevent the excavation efficiency from decreasing due to the blade load of the auger screw 6 becoming too large and the rotating speed of the auger screw 6 decreasing. The thrust of the auger screw 6 with respect to the ground is adjusted by operating the operation lever 16a while paying attention to the number of revolutions and the driving torque.

[0005]

In the above-described pile driver, it is necessary to frequently adjust the thrust of the auger screw 6 by the operation lever 16a, which imposes a heavy burden on the driver. Further, there is a large difference in excavation efficiency depending on the skill level of the driver.

It is an object of the present invention to provide a hydraulic circuit for a pile driver which can easily maintain the thrust of the excavating member within an appropriate range even if the driver is not a skilled driver.

[0007]

1 and 2, which show an embodiment, the invention of claim 1 is such that the excavating member 6 from the elevating member 5 attached to the reader 4 so as to be able to ascend and descend. The sprocket 8 that is hung down and attached to the elevating member 5 is meshed with the chain 7 that is fixed to the leader 4 in the vertical direction, and the sprocket 8 is rotationally driven by the hydraulic motor 14 provided in the elevating member 5 to move up and down. Member 5
Is applied to a hydraulic circuit of a pile driver that is lifted and lowered, and a hydraulic pump 10 for supplying pressure oil to the hydraulic motor 14 and an inlet side of the hydraulic motor 14 when the lifting member 5 is lowered (the pipeline 2
0a side), a connecting path 21 connecting the tank and the connecting path 2
1 and the variable relief valve 22 interposed therebetween achieve the above-mentioned object. According to the second aspect of the invention, the set pressure of the variable relief valve 22 can be adjusted in the cab of the pile driver.

[0008]

When the hydraulic motor 14 is driven to push the excavation member 6 into the ground, when the load on the cutting edge of the excavation member 6 is excessive, the set pressure of the variable relief valve 22 is lowered to reduce the maximum supply pressure to the hydraulic motor 14. , Thereby reducing the cutting edge load of the excavating member 6 to an appropriate value for the ground. After that, since the pressure exceeding the set pressure of the variable relief valve 22 does not act on the hydraulic motor 14, the hydraulic pump 1
Even if the supply of pressure oil from 0 to the hydraulic motor 14 is continued, an excessive blade edge load will not be applied. According to the invention of claim 2, the maximum value of the cutting edge load of the excavating member 6 can be set only by adjusting the set pressure of the variable relief valve 22 in the operator's cab.

Incidentally, in the section of means and action for solving the above-mentioned problems for explaining the constitution of the present invention, the drawings of the embodiments are used to make the present invention easy to understand. It is not limited to.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention in correspondence with FIG. 4 described above, and the same parts as in FIG. 4 are designated by the same reference numerals. In the following description, FIGS. 2 and 3 will be referred to for the schematic configuration of the pile driver to which the hydraulic circuit of FIG. 1 is applied. In the present embodiment, of the pair of pipelines 20a and 20b connecting the direction switching valve 12 and the hydraulic motor 14, the pipeline 20a on the inlet side of the hydraulic motor 14 when the elevating member 5 descends and the tank are connected. It is connected at 21. The variable relief valve 22 is provided in the connection passage 21. The set pressure of the variable relief valve 22 is set by a setting operation member (not shown) such as a dial. This setting operation member is provided in the cab 1a of the pile driver. When the setting operation member is integrated with the valve body portion of the variable relief valve 22, the variable relief valve 22 itself is arranged in the driver's cab, but the setting operation member is separated from the valve body portion and remotely operated by a wire or an electric signal. If possible, the setting operation member may be arranged in the driver's cab and the valve body portion may be provided at another place.

With the above construction, the set pressure of the variable relief valve 22 is lowered when the descending speed of the auger screw 6 is too fast. As a result, a part of the pressure oil supplied to the hydraulic motor 14 is discharged to the tank via the variable relief valve 22, the descent speed of the auger screw 6 is reduced, and the blade edge load is reduced. After reducing the set pressure of the variable relief valve 22 until the blade load reaches an appropriate value, the operating lever 1
Even if 6a is left in the descending side, the hydraulic motor 1
Since the maximum drive pressure of No. 4 is limited by the variable relief valve 22, an excessive cutting edge load does not act. Therefore, the blade edge load of the auger screw 6 is maintained in an appropriate range only by holding the operation lever 16a on the descending side, and good excavation efficiency can be obtained.

The hydraulic pumps 10 and 11 may be shared. The direction switching valve 12 may be a solenoid valve.

[0013]

As described above, according to the present invention,
By adjusting the setting pressure of the variable relief valve, the cutting edge load of the excavation member can be limited to a value suitable for the ground, so the driver must frequently adjust the supply state of pressure oil to the hydraulic motor for raising and lowering the excavation member. There is no. Therefore, the burden on the driver can be reduced, and the difference in excavation efficiency depending on the skill level of the driver can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a hydraulic circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing the overall configuration of a pile driver.

FIG. 3 is an enlarged view of a part III in FIG.

FIG. 4 is a conventional hydraulic circuit diagram.

[Explanation of symbols]

1 Pile driver body 4 Leader 5 Lifting member 6 Auger screw 7 Chain 8 Sprocket 10 Hydraulic pump for lifting auger screw 14 Hydraulic motor for lifting auger screw 16a Operation lever for lifting auger screw 20a Hydraulic motor when lifting the lifting member Inlet side pipe 21 Connection line 22 Variable relief valve

Claims (2)

[Claims] 1. A digging member is hung from an elevating member attached to a leader so as to be able to ascend and descend, and a sprocket attached to the elevating member is meshed with a chain fixed to the leader in the vertical direction, A hydraulic circuit of a pile driver in which a sprocket is rotationally driven by a hydraulic motor provided on the elevating member to elevate the elevating member, and a hydraulic pump for supplying pressure oil to the hydraulic motor,
A hydraulic circuit for a pile driver, comprising: a connection path that connects an inlet side of the hydraulic motor and a tank when the elevating member descends; and a variable relief valve interposed in the connection path. 2. The setting pressure of the variable relief valve can be adjusted in a driver's cab of a pile driver.
Hydraulic circuit for the mentioned pile driver.