JPS6135328B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic control circuit for a hammer for a pile driver, in which the hammer is driven by reciprocating motion of a hydraulic cylinder. The present invention relates to a hydraulic control circuit for a hammer for a pile driving machine, in which a hydraulic pump for driving a hoisting winch or the like is used to operate the hydraulic cylinder.

As is well known, in pile driving machines, the hammer drive is
Some devices use reciprocating motion of a hydraulic cylinder. The pile driver is also equipped with a hydraulic pump for running, rotating the upper revolving structure, and driving the hoisting winch.

Therefore, it is conceivable that the hydraulic cylinders are controlled by these hydraulic pumps. FIG. 1 shows a hydraulic control circuit for such a hammer for a pile driver. In the figure, 1 is an oil tank, 2 is a fixed displacement hydraulic pump that controls the swing hydraulic motor, and 3
and 3' are variable displacement hydraulic pumps that control the left and right traveling drive motors or the hoisting winch drive motors.

A control valve 4 for operating the pile driving machine body is provided on the discharge side of the fixed displacement hydraulic pump 2, and by switching the control valve 4, the swing hydraulic motor can be controlled, and the oil provided on the discharge side can be controlled. The discharge oil is supplied to the suction side of the variable displacement hydraulic pumps 3, 3' via the cooler 5.

A filter 6 and a back pressure check valve 7 are provided on the suction side of the variable displacement hydraulic pumps 3, 3'. Further, control valves 4A and 4B are provided on the discharge side of the variable displacement hydraulic pumps 3 and 3'.
By switching the control valves 4A and 4B, it is possible to control the traveling drive motor or the hoisting winch drive motor, and also to control the hammer drive hydraulic cylinder 10, which will be described later.

Switching valves 8, 8' are provided downstream of the control valves 4A, 4B, respectively.
By switching 8', control valve 4A,
Hydraulic cylinder 10 for driving the hammer with pressure oil from 4B
(hereinafter abbreviated as a hydraulic cylinder) or a return pipe 11. The switching valves 8, 8' are adapted to supply the combined pressure oil of the variable displacement hydraulic pumps 3, 3' or the individual pressure oils to the hydraulic cylinder 10 by switching the switching valves 8, 8' simultaneously or separately.

A directional switching valve 9 for controlling the hydraulic cylinder 10 is provided between the switching valves 8, 8' and the hydraulic cylinder 10. A check valve 12 is provided in the conduit a connecting the directional switching valve 9 and the rod chamber 10a of the hydraulic cylinder 10 to prevent it from flowing into the rod chamber 10a. A conduit b connecting the valve 9 is connected to the rod chamber 10a via a conduit c. Conduit c is provided with a check valve 12' that prevents fluid from flowing into rod chamber 10a from conduit b, and check valve 12' is opened by hydraulic pressure generated in conduit a. It's summery.

In this circuit, oil discharged from a fixed displacement hydraulic pump 2 is sent to a return line 11 via a control valve 4 and an oil cooler 5, and passes through a filter 6 to adjust the required flow rate to the variable displacement hydraulic pump 3,
3', and the flow rate other than that required by the variable displacement hydraulic pumps 3, 3' is supplied to the back pressure check valve 7.
is returned to the oil tank 1 by. The oil discharged from the variable displacement hydraulic pumps 3, 3' is circulated to the return pipe 11 when the switching valves 8, 8' are in the neutral positions of A and A' as shown in the figure; ′ is b,
When it is switched to the position B', it is supplied to the directional switching valve 9 side. When the directional control valve 9 is in the neutral position C as shown in the figure, the discharged oil is circulated to the return pipe 11.

Now, when the directional control valve 9 is switched to the D position, the water flows into the head chamber 10b of the hydraulic cylinder 10 through the pipe b, thereby extending the rod. That is, the hammer is raised.

Further, when the directional control valve 9 is switched to the position E, the discharged oil flows through the pipe a. At this time, the discharged oil is blocked by the check valve 12, and the check valve 12' of the pipe c is opened by the oil pressure.
Rod chamber 10a and head chamber 1 of hydraulic cylinder 10
It is in communication with 0b. That is, hydraulic cylinder 1
At 0, both chambers are in communication with the low pressure side, and the rod is contracted by the weight of the hammer. In other words, the hammer will fall freely.

When this rod reduction is performed, head chamber 1
The oil in 0b is circulated through pipe b to return pipe 11, and a portion of the return oil flows into rod chamber 10a through pipe c, thereby preventing negative pressure in the rod chamber. . By repeating the reciprocating motion of the rod of the hydraulic cylinder 10, the rod is raised and lowered continuously. In other words, it becomes possible to drive the pile with a hammer.

By the way, in the hydraulic control circuit for the pile driver hammer shown above, when the hammer is raised, that is, when the rod of the hydraulic cylinder 10 is extended, the rod chamber 1
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The amount of oil discharged from 0a is transferred to the return pipe 11 due to the volume difference between the head chamber 10b and the rod chamber 10a.
Since oil flows out at a flow rate lower than the normal flow rate of return oil, no surge pressure is generated in the return pipe 11.

However, when the hammer freely descends, that is, when the rod of the hydraulic cylinder 10 is contracted, the head chamber 10b
Since some of the oil in the head chamber 10b is allowed to flow into the rod chamber 10a and the hammer is allowed to fall freely (free fall speed + acceleration), most of the oil in the head chamber 10b is instantly drained into the return pipe 11. Moreover, since the amount of oil is combined with the amount of oil circulating in the return pipe 11, a surge pressure several times the normal pressure is generated in the return pipe 11. Therefore, there is a problem that the return pipe 11, oil cooler 5, and filter 6 are damaged.
In particular, the oil cooler 5 is problematic because it has a limited pressure resistance. Furthermore, when surge pressure occurs, there is a problem in that it adversely affects the suction performance of the variable displacement hydraulic pumps 3, 3' connected to the return pipe 11.

A first object of the present invention is to provide a hydraulic control circuit for a hammer for a pile driving machine, which can reliably reduce the surge pressure generated in the return pipe when the hammer is freely lowered, thereby minimizing the adverse effects on hydraulic equipment. We aim to provide the following.

A second object of the present invention is to completely absorb the surge pressure generated in the return line when the hammer is freely lowered, and to improve the hydraulic pressure of the hammer for a pile driving machine, which completely absorbs the surge pressure generated in the return line and does not have any adverse effects on hydraulic equipment due to the surge pressure. The purpose is to provide a control circuit.

In order to achieve the first object, the hydraulic control circuit of the hammer for a pile driver of the present invention includes at least one variable displacement hydraulic pump and supplies pressure oil to the suction side of the variable displacement hydraulic pump. a control valve provided on the discharge side of the variable displacement hydraulic pump; a switching valve that supplies pressure oil from the control valve to a hammer driving hydraulic cylinder or a return pipe; A directional switching valve for switching and controlling pressure oil to the cylinder, a bypass line branching from the return line and communicating with the oil tank, and a check valve for back pressure provided in the bypass line, When the hydraulic cylinder is operated to contract (in the free-falling direction of the hammer) by the switching valve, a portion of the return oil flowing through the return pipe flows out into the forward bypass pipe and flows into the return pipe. It is characterized by being configured to reduce the surge pressure that occurs.

In addition, in order to achieve the second object, the hydraulic control circuit of the hammer for a pile driver of the present invention includes at least one variable displacement hydraulic pump and a pressure oil on the suction side of the variable displacement hydraulic pump. a fixed displacement hydraulic pump that supplies the variable displacement hydraulic pump, a control valve provided on the discharge side of the variable displacement hydraulic pump, and a switching valve that supplies pressurized oil from the control valve to a hammer driving hydraulic cylinder or a return pipe; a directional switching valve for switching and controlling pressure oil to the hydraulic cylinder; a bypass line branching from the return line and communicating with the oil tank; a back pressure check valve provided in the bypass line; and the return line. and an accumulator installed in the conduit, and when the hydraulic cylinder is operated to contract (in the direction of free fall of the hammer) by the directional switching valve, a part of the return oil flowing through the return conduit is bypassed. The present invention is characterized in that the surge pressure generated in the return pipe can be absorbed by allowing the pressure to flow out into the pipe and absorbing pressure fluctuations by the accumulator.

Hereinafter, the present invention will be explained with reference to the drawings. 2 and 3 show an embodiment for achieving the first object of the present invention, and FIG. 2 is a hydraulic control circuit diagram of a hammer for a pile driver according to the present invention. In the drawings, the same reference numerals as in FIG. 1 represent the same or equivalent parts. A bypass line 13 is provided in the return line 11 on the downstream side of the directional control valve 9, and the bypass line 13 branches off from the middle and communicates with the oil tank 1.
4 is provided.

The back pressure check valve 14 is normally closed, but is opened when a large amount of oil is discharged into the return pipe 11 when the hydraulic cylinder 10 is contracted, and the back pressure check valve 14 is opened when the hydraulic cylinder 10 is contracted. Surplus oil in excess of the oil amount is allowed to flow out to the bypass pipe line 13.

Since the hydraulic control circuit of the present invention is configured as described above, when the rod of the hydraulic cylinder 10 is contracted (when the hammer is freely lowered), the combined oil of the rod chamber 10a and the head chamber 10b is instantly returned to the return pipe 11. When surge pressure is generated in the return pipe 11 due to the inflow of water into the pipe, the back pressure pipe is
When the oil valve 14 opens, a portion of the oil is transferred to the bypass pipe 1.
3 and is returned to the oil tank 1.

Therefore, the normal amount of oil flows through the return pipe 11, so the surge pressure is reduced.
As a result, the filter 6 provided in the return pipe 11
is hardly affected by the surge pressure. Furthermore, since almost no surge pressure acts on the discharge side pipe of the fixed displacement hydraulic pump 2 connected to the return pipe 11, the oil cooler 5 provided in the pipe is also affected by the surge pressure. do not have. Furthermore, fluctuations in the suction pressure of the variable displacement hydraulic pumps 3, 3' are also reduced.

FIG. 3 shows an application example of FIG. 2, and the difference from FIG. 2 is that the bypass pipe 13 in the return pipe 11 is
A throttle valve 15 is provided between the branch point X and the directional control valve 9 as a flow rate control throttle.

This application example functions effectively when the oil is used in a cold region, for example, and the viscosity of the oil is high.
That is, when the oil temperature is low, the viscosity of the oil is high, so there is a limit to the reduction of surge pressure. However, in this embodiment, if the absolute amount of return oil from the hydraulic cylinder 10 (combined oil in the rod chamber 10a and head chamber 10b) is limited by the flow rate control throttle valve 15, the return pipe 11 and Bypass line 13
Since the oil that has passed through the throttle valve 15 flows through the valve, the surge pressure can be reliably reduced even if the viscosity of the oil is high. In this case, the throttle valve 15
Since a fairly high surge pressure will be generated in the return line 11 between the directional control valve 9 and the return line 11, the line should be formed of a pressure-resistant pipe that can withstand the surge pressure.

4 and 5 show an embodiment for achieving the second object of the present invention, and FIG. 4 is a hydraulic control circuit diagram thereof. What is different in FIG. 4 from FIG. 2 is a bypass pipe 131 branching from the return pipe 11.
Through the combined action of this and the accumulator 16 provided in the middle of the return pipe 11, the surge pressure generated in the return pipe 11 can be completely absorbed.

To be more specific, the accumulator 16
is the return pipe 11 between the branch point X and the directional control valve 9
By further absorbing the surge pressure reduced by the bypass line 131 and the back pressure check valve 141, fluctuations in the surge pressure can be made uniform and reduced.

Therefore, in this embodiment, the directional control valve 9
The surge pressure generated in the return line 11 on the downstream side is completely absorbed and eliminated by the combined action of the accumulator 16 and the bypass line 131. As a result, the variable displacement hydraulic pumps 3, 3', the filter 6, the oil cooler 5, etc. are not adversely affected by surge pressure at all, so they are never damaged or their lifespans are shortened.

FIG. 5 shows an application example of FIG. 4, and the difference from FIG. 4 is that a flow rate control throttle valve 151 is provided in the return pipe 11 between the branch point The point is that That is, if the return oil from the hydraulic cylinder 10 (combined oil in the rod chamber 10a and head chamber 10b) is restricted by the throttle valve 151, the amount of oil that has passed through the throttle valve 151 is transferred to the return pipe 11 and the bypass pipe 131. Even if the viscosity of the oil is high, the surge pressure will be completely absorbed and eliminated. In this case, a fairly high surge pressure will act on the return line 11 between the throttle valve 151 and the directional control valve 9, so the line should be formed of a pressure-resistant pipe that can withstand the surge pressure. .

In the above-mentioned embodiment, an example was shown in which the accumulator 16 was provided in the return pipe 11 between the directional control valve 9 and the throttle valves 15, 151. It's okay. Also,
If the throttle valves 15 and 151 are provided in the return pipe 11 on the downstream side of the branch point X, the discharge flow rate to the oil cooler 5 and the filter 6 can be reliably controlled.

As described above, according to the present invention, since the bypass line branched from the return line is provided, it is possible to reduce the surge pressure generated in the return line when the hammer freely descends. Therefore, it is possible to provide a hydraulic control circuit for a hammer for a pile driving machine that does not adversely affect hydraulic equipment due to surge pressure.

In addition, a bypass pipe branched from the return pipe,
With an accumulator provided in the return pipe,
During the free fall of the hammer, the surge pressure generated in the return line can be completely absorbed. Therefore, it is possible to provide a hydraulic control circuit for a hammer for a pile driving machine that does not have any adverse effect on hydraulic equipment due to surge pressure.

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[Brief explanation of the drawing]

Fig. 1 is a hydraulic control circuit diagram proposed to be applied to a hammer for a pile driver, Fig. 2 is a hydraulic control circuit diagram for a hammer for a pile driver showing a first embodiment of the present invention, and Fig. 3 is a hydraulic control circuit diagram for a hammer for a pile driver. is a hydraulic control circuit diagram of a hammer for a pile driving machine showing an application example of FIG. 2, and FIG.
Fig. 5 is a hydraulic control circuit diagram of a hammer for a pile driver showing an example of application of Fig. 4; 1...Oil tank, 2...Fixed capacity hydraulic pump, 3, 3'...Variable capacity hydraulic pump, 4A,
4B...Control valve, 8,8'...Switching valve,
9... Directional switching valve, 10... Hydraulic cylinder for hammer drive, 11... Return pipe line, 13,131... Bypass pipe line, 14,141... Check valve for back pressure, 15,151... For flow rate control Throttle valve, 16...
…Aki Yumuleta. 〓〓〓〓

Claims (1)

[Claims] 1. At least one variable displacement hydraulic pump;
A fixed displacement hydraulic pump that supplies pressure oil to the suction side of the variable displacement hydraulic pump, a control valve provided on the discharge side of the variable displacement hydraulic pump, and a control valve that supplies pressure oil from the control valve to hydraulic pressure for driving the hammer. A switching valve that supplies the cylinder or return pipe, a directional switching valve that switches and controls pressure oil to the hydraulic cylinder, a bypass pipe that branches from the return pipe and communicates with the oil tank, and the bypass pipe. When the hydraulic cylinder is operated to contract (in the direction of free fall of the hammer) by the directional switching valve, a portion of the return oil flowing through the return pipe is removed. A hydraulic control circuit for a hammer for a pile driving machine, characterized in that the hydraulic pressure control circuit is configured to flow out into the bypass pipe to reduce surge pressure generated in the return pipe. 2. The hydraulic control circuit for a hammer for a pile driving machine according to item 1, wherein the return pipe has a flow rate control throttle in the middle thereof. 3 at least one variable displacement hydraulic pump;
A fixed displacement hydraulic pump that supplies pressure oil to the suction side of the variable displacement hydraulic pump, a control valve provided on the discharge side of the variable displacement hydraulic pump, and a control valve that supplies pressure oil from the control valve to hydraulic pressure for driving the hammer. A switching valve that supplies the cylinder or return pipe, a directional switching valve that switches and controls pressure oil to the hydraulic cylinder, a bypass pipe that branches from the return pipe and communicates with the oil tank, and the bypass pipe. The hydraulic cylinder is reduced by the direction switching valve (in the direction of free fall of the hammer).
When operated in such a way, a part of the return oil flowing through the return line flows out into the bypass line, and the pressure fluctuations are absorbed by the accumulator, thereby reducing the surge pressure generated in the return line. A hydraulic control circuit for a hammer for a pile driving machine, characterized in that it is configured to absorb water. 4. The hydraulic control circuit for a hammer for a pile driving machine according to item 3, wherein the return pipe has a flow rate control throttle on the downstream side of the accumulator.