JP2003213682A - Lifting and lowering control means - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lifting and lowering control means with good operability by eliminating the unexpected free fall of a hoist unit. <P>SOLUTION: A lifting and lowering lever 10 capable of operating the hoist unit mounted on the leader of a pile driver by switching the stop and lifting/ lowering of the hoist unit to a neutral position, an up position and a down position comprises a lifting/lowering free switch 12 for freely lowering the hoist unit. The lifting or power lowering is performed by the switching of the lifting/lowering lever 10 to the up position or down position, the free lowering is performed by the input operation of the lifting/lowering free switch 12 in addition to the switching of the lifting/lowering lever 10 to the down position, and the stop of lifting and lowering is performed by the switching of the lifting/ lowering lever 10 to the neutral position. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an elevating control means for an elevating device which elevates and lowers a steel pipe pile or the like having spiral blades at its lower end along a leader while rotating it by a rotary drive device.

[0002]

2. Description of the Related Art For example, in a pile driver, as shown in FIG. 6, an upper revolving structure 102 is rotatably provided on a lower traveling structure 101, and a leader 103 is mounted on a front portion of the upper revolving structure 102 by a backstay cylinder 104. It is supported so that it can be undulated. The guide pipe 1 is attached to the leader 103 installed upright.
The lifting device 110 is mounted so as to slide 05, and the lifting device 110 provides an auger 1 for rotating a steel pipe pile or the like.
20 is integrally configured. Therefore, according to such a pile driving machine 100, a steel pipe pile or the like is connected to the auger 120, rotation is given by the auger 120, and the elevating device 110 descends along the reader 103, so that the steel pipe pile or the like is rotationally pressed into the ground. To be done.

As a method of raising and lowering the elevating device 110 along the reader 103, for example, a rack mounted on the reader 103 is engaged with a pinion rotating by a hydraulic motor 111 of the elevating device 110 itself, and the hydraulic motor 111 of the hydraulic motor 111 is rotated. There is a device that raises and lowers the lifting device along the reader 103 by driving. In addition, as another method for elevating the elevating device 110, the reader 103
There is also a chain type in which a chain in which an elevating device is connected is spanned over sprockets provided above and below, and the sprocket is rotated by a hydraulic motor to feed the chain in a predetermined direction to elevate the elevating device along a leader.

By the way, in the case where the steel pipe pile has spiral blades, even if the auger 120 rotates the blades, the blades bite into the ground and the steel pipe piles generate thrust by itself, so that the auger 120 does not have a pushing force. It is driven into the ground naturally by the rotating torque from 120. On the other hand, steel pipe piles that are press-fitted into rotation are driven into the ground while consolidating the surrounding ground, but in order to build piles with increased bearing capacity, it is necessary to press-fit them without disturbing the surrounding ground. Therefore,
For that purpose, the elevating device that rotates the steel pile and lowers it together does not force the steel pile during rotation press-fitting or conversely restrict the press-fitting and pull upward. It is necessary to match the blade pitch of the steel pipe pile.

Such a point can be dealt with by adjusting the driving speed of the hydraulic motor and adjusting the descending speed to the blade pitch of the steel pipe pile. However, there is a problem that the operation requires a great deal of labor and requires a high degree of skill. Therefore, conventionally, for example, JP-A-8-26996
In Japanese Patent Laid-Open No. 4 (first conventional example) and Japanese Patent Application Laid-Open No. 2001-98879 (second conventional example), the rotation of a hydraulic motor for raising and lowering the lifting device is made free, and the lifting device 110 is used.
It has been proposed to put the weight on the steel pipe pile connected to the auger 120 so that the lifting device is freely lowered according to the rotational press fit of the steel pipe pile.

[0006]

However, the free fall of the lifting device is effective in the case where a steel pipe pile with blades is rotationally press-fitted without disturbing the ground, but as shown in FIG. If the lifting device 110 at a predetermined position is accidentally freely lowered, it is expected that the lifting device 110 will suddenly drop and the pile driver 100 will be damaged, or a dangerous situation will occur.

The free fall of the lifting device is performed by switching the hydraulic circuit for supplying hydraulic oil from the hydraulic pump to the hydraulic motor. In the first and second conventional examples, the control valve for operating the raising and lowering device is in a neutral state, and the short circuit valve is switched to freely lower the valve. Therefore, if the short-circuit valve is switched by a simple switch operation, the switch may be turned on by some kind of momentum and the lifting device 110 may suddenly descend suddenly. Further, in the case of the first and second conventional examples, while raising and lowering the hydraulic motor by moving it up and down is performed by operating the control valve, free fall operation is performed by the switching valve. Therefore, when a sudden stop is required during free descent, there is also a problem that the operation cannot be discriminated by a quick judgment, and the operation cannot be quickly and appropriately handled.

[0008] Therefore, in order to solve the above problems, an object of the present invention is to provide an elevating control means which eliminates the inadvertent free descent of the elevating device and has good operability.

[0009]

The lifting control means of the present invention raises or lowers the power of a lifting device mounted on a leader of a pile driver by the rotational output of a hydraulic motor, and also frees the rotation of the hydraulic motor. A control circuit composed of a hydraulic circuit that controls the supply of hydraulic oil that drives a hydraulic motor, and an electric circuit that controls a fluid control device that constitutes the hydraulic circuit, and the lifting operation of each And an operating section for switching the control circuit to a state in which the operating circuit is executed. The operating section can be operated by switching stopping and ascending / descending of the elevating device to a neutral position, an ascending position, and a descending position. The elevating lever is equipped with an elevating free switch for freely lowering the elevating device,
The raising or lowering of power is performed by switching the raising or lowering lever to the raising or lowering position, and the free lowering is performed by inputting the raising or lowering free switch in addition to switching to the lowering position of the raising or lowering lever. Is characterized by.

Therefore, according to the present invention, when the operator freely lowers the elevating device, a two-step operation of pushing the elevating lever with the elevating lever in the lowered position is performed. It is possible to prevent an erroneous operation in which the vehicle freely drops freely as in the case.
In the case of work such as rapidly lowering the lifting device, the lifting lever is switched to the lowered position as in the case of power lowering, so it is possible to let the operator know that the lifting device will lower before pressing the lifting free switch, ensuring the operator's safety. Has the effect of promoting

The elevation control means of the present invention preferably has the following embodiments. The operation section is configured to stop the free fall of the lifting device by switching to a neutral position of the lifting lever. The control circuit switches the hydraulic circuit between an ascending state and a power descending state in which hydraulic oil from the hydraulic pump is supplied to the hydraulic motor, and a free descending state in which the hydraulic oil is circulated between the input / output ports of the hydraulic motor. An electromagnetic valve and an electromagnetic valve for cutting off the supply of hydraulic oil to the hydraulic motor when the elevating lever is switched to the lowered position are provided, and are connected to the power source of the solenoid of each electromagnetic valve connected to the electric circuit. The up / down free switch is used for switching.

The electric circuit has a first relay that operates in response to switching of the elevating lever to the lowered position and a second relay that operates when the elevating free switch is turned on. A self-holding circuit for energizing the solenoid of each of the solenoid valves by the operation of the relay and for maintaining the second relay in the operating state even when the lift free switch is turned off. The hydraulic circuit is connected to a pressure switch that detects the hydraulic pressure applied when the elevating lever is switched to the lowered position and is turned on, and the first relay turns on the pressure switch.
It should work depending on the state. The electric circuit has a relay in which a pressure switch that detects the hydraulic pressure applied when the lifting lever is switched to the lowered position and is turned on and the lifting free switch are connected in series. The solenoid of each solenoid valve is energized. The electric circuit operates a confirmation member that notifies the free fall of the lifting device by the operation of each of the relays.

Therefore, the stop operation of the elevating device that freely descends similarly to the power down has a good operability because it only returns the elevating lever to the neutral position, and it is possible to appropriately respond even when it is necessary to make a quick judgment in an emergency. . In addition, if the self-holding circuit is configured, the lifting / lowering switch is pressed only once, and then the lifting / lowering device is freely lowered. At that time, the confirmation member is activated to emit, for example, light or sound. This allows the operator to confirm that there is no power drop. On the other hand, in the non-self-holding type in which the pressure switch and the lift free switch are connected in series,
Although the lifting / lowering free switch must be kept pressed during the free fall, the operator can recognize that the current work is the free fall, which is preferable from the viewpoint of work safety.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of a lifting control means according to the present invention will be described below with reference to the drawings. First, as shown in FIG. 1, the lifting device 1 is configured integrally with the auger 6, and in the present embodiment, a rack and pinion type is used for the method of lifting the lifting device 1 along the reader. The lifting device 1 is provided with a pair of pinion gears 2a to 2d vertically sandwiching the rack of the leader, and a total of four gears are engaged with the rack.
a to 3d are provided respectively. On the other hand, the auger 6 integrally formed with the lifting device 1 has a lower attachment 8 protruding from a gear case 7, and the rotation from a hydraulic motor 9 is transmitted to a steel pipe pile connected to the auger 6 via a speed reducer. It is supposed to be done.

In the present embodiment, a rack and pinion type will be described as an example, but as another method of raising and lowering the raising / lowering device 1, as described above, a chain is attached to the sprockets arranged at the upper and lower ends of the leader. There are a chain type that spans a wire and a winch type that connects a wire rope to the lifting device 1 and applies a hoisting and pushing force. The lifting control according to the present invention is similarly applied to such a structure. Means can be applied.

The lifting control means of the present embodiment uses the lifting device 1 shown in FIG. 1 and the leader 1 of the pile driving machine 100 as shown in FIG.
When it is mounted on 03 so as to be able to move up and down, the rotation control of the hydraulic motors 3a to 3d for moving up and down the lifting device 1 is performed. More specifically, the hydraulic circuit between the hydraulic pumps that supply hydraulic oil to the hydraulic motors 3a to 3d is directly handled by an electric circuit or an operator to which a solenoid or the like for operating an electromagnetic valve provided in the hydraulic circuit is connected. The control is performed by operating the operation part. The lifting control means is composed of such a control circuit section (hydraulic system and electric system) and an operating section, and is particularly characterized by the operability and safety of the operating section which the operator directly handles. Figure 2
FIG. 6 is a diagram showing such an operation unit.

As shown in the figure, the hydraulic motors 3a to 3d are located in the cockpit so that the operator sitting in the cockpit can reach them.
Is installed, that is, an elevating lever 10 for operating the elevating device 1 for elevating and stopping. The lifting lever 10
It can be switched between a neutral position shown by the solid line in the figure, an ascending position tilted forward (left side in the drawing), and a descending position tilted backward (right side in the drawing). Further, in this embodiment, when the operator puts his hand on the knob 11 at the upper end of the elevating lever 10, the elevating free switch 12 is installed at a position where it can be operated with a finger.

The lift-free switch 12 is used for the hydraulic motor 3
Unlike the case where the a to 3d is driven to increase or the power is lowered, the rotation of the hydraulic motors 3a to 3d is made to be free, and the lifting device 1 is freely lowered by its own weight.
That is, when the up-and-down free switch 12 is turned on, the input / output ports of the predetermined hydraulic motors 3a to 3d are connected to circulate the hydraulic oil between the hydraulic motors 3a to 3d which rotate with the lowering. It is for. However, simply pressing the lifting / lowering free switch 12 does not make the rotation free, and the control circuit described later requires that the lifting / lowering lever 10 is tilted to the lowering side, and the lifting / lowering lever 10 is set to the neutral position. In some cases, the up / down free switch 12 does not work.

Therefore, the elevating control means of this embodiment uses the elevating lever 10 and the elevating free switch 12 to switch among three patterns of ascending, power lowering and free lowering by driving the hydraulic motors 3a to 3d. It was made possible. A lift-free confirmation lamp 13 is provided on the operation portion and is turned on to allow the operator to confirm it in the free fall state.

Next, a specific operation of the operation unit by the operator will be described. When the elevating lever 10 is in the neutral position shown by the solid line in FIG. 2, the hydraulic motors 3a to 3d are not supplied with hydraulic oil and their rotation is restricted, and the elevating device 1 is stopped at a predetermined position of the reader. Therefore, when raising or lowering the elevating device 1, the operator sitting in the cockpit tilts the elevating lever 10 forward or backward as shown by the chain double-dashed line in the figure. When the elevating lever 10 is tilted forward, the hydraulic motors 3a to 3d supplied with hydraulic oil rotate in a predetermined direction, the pinion gears 2a to 2d roll on the rack, and the elevating device 1 ascends along the leader. To do. Conversely, the lifting lever 10
When the vehicle is tilted backward, the hydraulic motors 3a to 3d output reverse rotations, which causes the pinion gears 2a to 2d.
d rolls the rack, and the elevating device 1 descends along the leader.

Further, if the operator tilts the elevating lever 10 backward and presses the elevating / lowering free switch 12, the working oil circulates between the hydraulic motors 3a to 3d, the rotation becomes free, and the elevating / lowering device 1 freely descends. become. Therefore, for example, when driving a steel pipe pile having a spiral blade with the auger 6 and the blade pitch of the steel pipe pile and the descending speed of the elevating device 1 do not match, the elevating lever 1 is the same as when the power is lowered.
It suffices to tilt 0 and press the up / down free switch 12. Then, the lifting / lowering device 1 is placed on the steel pipe pile and is in a state in which its own weight is absorbed, and descends as the steel pipe pile penetrates into the ground by the propulsive force of the spiral blade. Therefore, an unreasonable pushing force or a pulling force does not act on the steel pipe pile, and the steel pipe pile can be rotationally press-fitted without disturbing the ground only by rotating the auger 6.

In a self-holding type control circuit, which will be described later, if the elevating free switch 12 is pushed once, the elevating lever 10 is simply tilted in the same way as the power drop after the operator operates the power. You may misunderstand that you are descending. Therefore, in the case of free descent, the lifting / lowering free confirmation lamp 13 is turned on, and the descent status of the lifting / lowering device 1 can be checked. On the other hand, the hydraulic motors 3a-3
d driven up and down, and hydraulic motor 3
In any of the free fall of rotations a to 3d, the hydraulic motor 3a is returned by returning the elevating lever 10 to the neutral position.
The rotation of 3d is restricted, and the lifting or lowering of the lifting device 1 is stopped accordingly.

As described above, in the lifting control means of the present embodiment, when the operator freely lowers the lifting device 1, the lifting lever 10 is tilted to the lowering side and the lifting free switch 12 is turned on in two steps. It is like this.
Therefore, it is possible to prevent an erroneous operation such as a case where only a switch operation is performed, which causes an accidental free descent, which is safe. Further, when the lifting device 1 is to be dropped, the lifting lever 10 is tilted in the same direction as the power drop, so that it is possible to recognize that the lifting device 1 is lowered before pressing the lifting free switch 12. , Has the effect of encouraging operators to ensure safety. Further, since the raising, power-lowering, and free-falling stop operations only return the elevating lever 10 to the neutral position, appropriate measures can be taken even in the event of an emergency determination. Further, the lift free switch 12 provided below the knob 11 of the lift lever 10 has good operability.

Next, by operating the elevating lever 10 and the elevating / lowering switch 12 as described above, the hydraulic motors 3a ...
An example of the control circuit for controlling the driving of 3d will be described. FIG. 3 is a diagram showing a hydraulic circuit for feeding hydraulic oil to the hydraulic motors 3a to 3d of the lifting device 1 among the control circuit units forming the lifting control means. Hydraulic motor 3
a to 3d are negative brakes 4a to 4 that regulate the rotation thereof.
Cylinders 5a to 5d are provided which have a d and which are braked by the urging force of the spring and released by hydraulic pressure. Hydraulic motor 3a-
3d and cylinders 5a to 5d correspond to the lifting device 1 shown in FIG.
The hydraulic pumps 21, 22, 2 of the pile driver machine main body are lifted by the hydraulic hoses hung through the leader.
Connected to 3.

First, the hydraulic motors 3a to 3d are connected to the driving hydraulic pump 21 via the control valve 25, and the operating oil sent from the hydraulic pump 21 by switching the control valve 25 is hydraulic motors 3a to 3d.
3d is supplied from the port on the ascending or descending side. A counter balance circuit 26 is connected between the control valve 25 and the hydraulic motors 3a to 3d so that the lifting / lowering device 1 can hold its position and perform a stable lifting operation.

Electromagnetic valves 31 and 32 are connected from the counter balance circuit 26 to the ascending side flow passage 41 and the descending side flow passage 42 on the hydraulic motors 3a to 3d side, and the hydraulic motors 3a to 3d are connected.
Of the hydraulic motors 3a and 3b and the hydraulic motors 3c and 3c by switching between the rising side flow path circuit communicating with the rising side port and the falling side flow path communicating with the falling side port.
Between 3d and 3d, it connects so that one ascending side port may be connected to the other descending side port to form a circulation flow path. On the other hand, the hydraulic pump 21 of the counter balance circuit 26
A shuttle valve 27 is provided on the side of the negative brake 4a.
A solenoid valve 33 is connected between the 4d cylinders 5a to 5d. When the hydraulic motors 3a to 3d rotate, the solenoid valve 33 causes the cylinders 5a to 5d to have the hydraulic pump 21 or
The hydraulic pressure from the hydraulic pump 22 for pilot pressure acts.

To the hydraulic pump 22 for pilot pressure, remote control valves 28 and 29 which can be switched by operating the lifting lever 10 shown in FIG. 2 are connected, and the pilot from the hydraulic pump 22 is switched by switching the remote control valves 28 and 29. It is arranged so that the pressure acts on the operation ports p1 and p2 of the control valve 25. In addition,
Remote control valve 29 and control valve 25 on the descending side
An electromagnetic valve 34 is provided between the control valve 25 and the control valve 25 so that the lower operation port p2 of the control valve 25 can communicate with the tank 38 side. Further, a pressure switch 35 for detecting the pilot pressure applied to the operation port p2 of the control valve 25 is provided.

By the way, when the hydraulic motors 3a to 3d are freely descended so that they are free to rotate, the hydraulic oil runs short due to a motor leak, and the hydraulic motors 3a to 3d due to the vacuum phenomenon.
There is a possibility that a failure may occur in d. Therefore, a hydraulic pump 23 for charging is provided to make up for the shortage of hydraulic oil, and the hydraulic oil is supplied to the hydraulic motors 3a to 3d when the lifting device 1 is freely lowered.

Next, FIG. 4 is a diagram showing an electric circuit operated by the lifting / lowering free switch 12 in the control circuit portion constituting the lifting / lowering control means. First, the first relay 4
1 is connected to the power source (not shown) via the pressure switch 35, and the second relay 42 is connected to the power source (not shown) via the lift free switch 12. As described above, the pressure switch 35 detects the pilot pressure applied to the control valve 25, and is turned on by the lowering operation of the elevating lever 10. Also, lift free switch 12
Is an a contact that is turned on when the operator presses it, but the electric circuit has a first relay 41 and a second relay 42.
Constitutes a self-holding circuit so that the operating state is maintained even when the lift free switch 12 is released. Further, the solenoids 31s, 32s, 33s, 34s of the solenoid valves 31, 32, 33, 34 and the lift-free confirmation lamp 13 are connected to the first relay, and the first and second relays 4 are connected.
It is configured to be energized by the operations of 1, 42.

Next, the operation of raising and lowering the lifting device 1 and freely lowering the lifting device 1 by means of the control circuit portion constituting such lifting control means will be described below separately for each case. First, when the lift lever 10 is in the neutral position as shown by the solid line in FIG. 2, the hydraulic circuit has the flow path shown in FIG. That is, in the control valve 25, the operation ports p1 and p2 are connected to the tank 38 via the remote control valves 28 and 29, and the pilot pressure does not act on the spool that switches the flow path. Therefore, in the flow path of the control valve 25, the hydraulic oil sent from the hydraulic pump 21 exits the control valve 25 and is returned to the tank 38, and the hydraulic oil is not sent to the hydraulic motors 3a to 3d and the counter balance circuit 26 It is blocked by and the negative brakes 4a to 4d are still in effect. Therefore, at this time, the lifting device 1 includes the pinion gear 2a.
2d are engaged with the rack and stopped at a predetermined height position of the leader.

Next, when raising the elevating device 1,
The elevating lever 10 is tilted to the front raised position by the operator. By such operation of the elevating lever 10, the remote control valve 28 on the ascending side is switched, and the hydraulic pump 22 communicates with the operation port p1 of the control valve 25. The spool of the control valve 25 is actuated by the pilot pressure acting on the operation port p1 side, and the working oil sent from the hydraulic pump 21 flows to the ascending side passage 41 by the switched passage.

From the control valve 25 to the ascending side flow path 4
The hydraulic fluid flowing to No. 1 flows to the pilot passage 43 by the shuttle valve 27, and further to the brake passage 44 through the electromagnetic valve 33. Therefore, the cylinders 5a to 5d connected to the brake flow path 44 are pressurized by the hydraulic oil, and the negative brakes 4a to 4d of the hydraulic motors 3a to 3d are released. On the other hand, the hydraulic oil flowing from the counter balance circuit 26 to the ascending side flow passage 41 is the hydraulic motors 3 a, 3
solenoid valve 3 directly to hydraulic motors 3c and 3d.
It is sent to each ascending port via 1. Therefore, the hydraulic motors 3a to 3d each output rotation in a predetermined direction, and the pinion gears 2a to 2d meshed with the rack.
Rolls and the lifting device 1 rises along the leader.

To stop the ascent, the operator may return the elevating lever 10 to the neutral position. As a result, the remote control valve 28 is switched, and the control valve 25, which is disconnected from the hydraulic pump 22, returns to the state shown in FIG. Therefore, the hydraulic motors 3a to 3d are the same as the hydraulic pump 2
1, the hydraulic oil is no longer supplied, the counter balance circuit 26 blocks the negative oil, and the negative brakes 4a to 4a.
When d is applied, the rotation is stopped and the lifting of the lifting device 1 is stopped.

Next, when the power of the elevating device 1 is lowered, the elevating lever 10 is tilted to the rear lowering position by the operator. By such operation of the elevating lever 10, the remote control valve 29 on the descending side is switched, and the hydraulic pump 22 communicates with the operation port p2 of the control valve 25. The spool of the control valve 25 is actuated by the pilot pressure acting on the operation port p2 side, and the working oil sent from the hydraulic pump 21 by the switched flow path flows to the descending side flow path 42.

From the control valve 25 to the descending side flow path 4
The hydraulic fluid that has flowed to 2 flows to the pilot passage 43 by the shuttle valve 27, and further to the brake passage 44 through the electromagnetic valve 33. Therefore, the cylinders 5a to 5d connected to the brake flow path 44 are pressurized by the hydraulic oil, and the negative brakes 4a to 4d of the hydraulic motors 3a to 3d are released. On the other hand, the hydraulic oil that further flows from the counter balance circuit 26 through the descending side flow passage 42 is the hydraulic motors 3c and 3c.
d directly to the hydraulic motors 3a and 3b, and the solenoid valve 3
It is sent to each descending port via 2. Therefore, the hydraulic motors 3a to 3d each output rotation in a predetermined direction, and the pinion gears 2a to 2d meshed with the rack.
And the lifting device 1 drops its power along the leader.

When stopping this power drop,
When the operator returns the lift lever 10 to the neutral position, the control valve 25 is returned to the state shown in FIG. 3 as in the case where the lift is stopped, the rotation of the hydraulic motors 3a to 3d is stopped, and the power of the lift device 1 is lowered. Can be stopped.

Next, the case of performing free descent will be described. When the elevating device 1 is freely lowered, the operator moves the elevating lever 10 to the rear lowering position and pushes the elevating free switch 12 (the elevating lever 10 may be tilted while pushing the elevating free switch 12). In this case, if the raising / lowering lever 10 is tilted to the lower side, the remote control valve 29 is switched, and the control valve 25 is switched as it is. When the remote control valve 29 is switched, the pressure switch 35 on the secondary side thereof is turned on, the first relay 41 is connected to the power source, and the switches e and f shown in FIG. 4 are switched. At this stage when the lift free switch 12 is not pressed, the hydraulic circuit is in the same state as in the case of the power drop described above.

On the other hand, when the lift free switch 12 is pressed, the second relay 42 is connected to the power source, and the switches g and h shown in FIG. 4 are switched. As a result, each relay 4
The lift-free confirmation lamp 13, the solenoids 31s, 32s, 33s, and the solenoid 34s are connected to a power source via the switches g, e of 1, 42, and the solenoid valves 31, 32, 33, 34 on the hydraulic circuit are switched. .

Then, when the solenoid valve 34 is switched,
The operation port p2 of the control valve 25 is disconnected from the remote control valve 29 connected to the hydraulic pump 21 and communicates with the tank 38. Therefore, the control valve 25 will be in the same state as when the operator returned the neutral position to the hydraulic levers 3a to 3d even when the elevating lever 10 was tilted to the lowered position, and the hydraulic oil from the hydraulic pump 21 was not supplied to the hydraulic motors 3a to 3d. The switching of the solenoid valve 33 is performed by the hydraulic pump 22 through the brake flow passage 44 and the cylinders 5a to 5d.
To the negative brake 4a-4d by the pilot pressure.
Is released and the hydraulic motors 3a to 3d are brought into a rotation-free state. Further, by switching the solenoid valves 31 and 32, the hydraulic motors 3a and 3b are divided into a pair of hydraulic motors 3a and 3b on the upper side and a pair of hydraulic motors 3c and 3d on the lower side. A circulation passage is formed in which the rising side port of is connected to the falling side port of the hydraulic motors 3c, 3d (3a, 3b) of the other set.

In this way, the lifting device 1 in which the rotation of the hydraulic motors 3a to 3d is free is in a free descent state in which it cannot support itself and falls by its own weight. Pinion gear 2a that rolls the rack when the lifting device 1 freely descends
Inversely, rotation is given to the hydraulic motors 3a to 3d from ~ 2d, and the hydraulic oil on the flow path is sent out. Therefore, the hydraulic oil sent from the ascending side ports of the hydraulic motors 3a, 3b enters from the descending side ports of the hydraulic motors 3c, 3d, and the working oil sent out from the ascending side ports descends again of the hydraulic motors 3a, 3b. Enter the side port and repeat circulation.
At this time, the hydraulic oil is supplied from the hydraulic pump 23 for charging through the charge passage 45 so that the hydraulic oil does not run short due to a motor leak in the hydraulic motors 3a to 3d.

In the electric circuit, even when the lift free switch 12 is released and turned off, the state in which the power source is connected to the second relay 42 via the switches h and f is maintained, and the switches g and h are turned on. The self-holding state remains switched. Therefore, when the elevating lever 10 is tilted down and the elevating free switch 12 is pressed, the elevating lever 10
As long as the pressure switch 35 is not returned to the OFF state by returning to, the lifting device 1 is freely lowered. Therefore, after pressing the up / down free switch 12, the operator may not know whether the free fall is the same as the power down operation, but since the up / down free confirmation lamp 13 is lit, it may be a free fall. I can confirm.

In order to stop the free lowering of the elevating device 1, if the operator returns the elevating lever 10 to the neutral position,
The remote control valve 29 is switched to the state shown in FIG. 3, the communication with the hydraulic pump 22 is cut off, and the pressure switch 35 is turned off. Therefore, the first relay 41 is de-energized to switch the switches e and f, and the second relay 42 is de-energized to switch the switches g and h. Therefore, the lift-free confirmation lamp 13 is turned off, and the solenoids 31s, 32s, 33s and the solenoid 34 are turned on.
The excitation of s is released and each solenoid valve 31, 32, 33, 34 is switched to the state shown in FIG. Solenoid valves 31, 32,
By switching 33, the circulation of the hydraulic oil is stopped, the negative brakes 4a to 4d are applied, and the rotations of the hydraulic motors 3a to 3d are stopped, so that the rotations of the pinion gears 2a to 2d are stopped and the free descent is stopped.

Although one embodiment of the lifting control means has been described above, the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention. It is also possible to take other forms for the control circuit such as the elevating lever 10 that executes elevating and lowering in accordance with the operation of the operator.
As shown in, a solenoid 31s or the like may be connected to the second relay 42 that operates when the pressure switch 35 and the lift free switch 12 are turned on. In this case, the operator needs to hold down the up / down free switch 12 while freely lowering, but it is possible to recognize that the current work is free fall, which is preferable from the viewpoint of work safety.

Further, for example, the confirmation member for notifying the free fall may be one that emits a confirmation sound instead of the lift-free confirmation lamp 13. Further, in the hydraulic circuit, as in the first conventional example, a short-circuit valve for connecting and disconnecting the flow paths connected to the hydraulic oil input / output ports of the hydraulic motor is provided, or as in the second conventional example. Alternatively, a bypass circuit connected to the tank may be provided in the rising circuit of the hydraulic motor, and a switching valve may be provided in the bypass circuit.

[0045]

Therefore, according to the present invention, the lifting lever that can be operated by switching the stopping and lifting of the lifting device to the neutral position, the rising position and the descending position is provided with the lifting free switch for freely lowering the lifting device. Since raising or lowering the power is performed by switching the lifting lever to the raised or lowered position, and free lowering is performed by inputting the lifting free switch in addition to switching the lifting lever to the lowered position. It has become possible to provide a lift control means with good operability, eliminating the need for free fall.

[Brief description of drawings]

FIG. 1 is a view showing a lifting device.

FIG. 2 is a diagram showing an operating unit of a lifting control means.

FIG. 3 is a diagram showing a hydraulic circuit in a control circuit unit of a lifting control unit.

FIG. 4 is a diagram showing an electric circuit in a control circuit section of the lifting control means.

FIG. 5 is a diagram showing an electric circuit in a control circuit section of the lifting control means.

FIG. 6 is a view showing a pile driver equipped with a lifting device.

[Explanation of symbols]

1 Lifting device 2a, 2b, 2c, 2d pinion gear 3a, 3b, 3c, 3d hydraulic motor 10 Lifting lever 12 Lift free switch 13 Lift-free confirmation lamp 21,22,23 hydraulic pump 25 control valve 28,29 remote control valve

Claims (7)

[Claims] 1. A lifting device mounted on a leader of a pile driving machine is raised or lowered by rotating output of a hydraulic motor,
Each lifting / lowering operation in which the rotation of the hydraulic motor is freed and freely descends is composed of a hydraulic circuit that controls the supply of hydraulic oil that drives the hydraulic motor and an electric circuit that controls a fluid control device that constitutes the hydraulic circuit. Control circuit,
And an operating unit that switches the control circuit to a state in which each lifting operation is executed, and the operating unit switches stopping and lifting of the lifting device to a neutral position, a rising position, and a descending position. An elevating lever that can be operated by means of an elevating lever is provided with an elevating free switch for freely lowering the elevating device, and the ascending or power lowering is performed by switching the elevating lever to an ascending position or a descending position, and the free descending is performed by the elevating lever descending position The lifting control means is characterized in that it is operated by an input operation of a lifting free switch in addition to the switching to. 2. The elevating control means according to claim 1, wherein the operation portion is configured to stop the free lowering of the elevating device by switching to a neutral position of an elevating lever. Lifting control means. 3. The lift control means according to claim 1 or 2, wherein the control circuit includes an ascending state and a power descending state in which hydraulic oil from a hydraulic pump is supplied to the hydraulic motor, and the hydraulic motor. A solenoid valve that switches the hydraulic circuit to a free-fall state in which hydraulic oil circulates between the input and output ports, and a solenoid valve that cuts off the supply of hydraulic oil to the hydraulic motor when the lifting lever is switched to the lowered position. And an elevation control means for switching between the solenoid and the power source of the solenoid of each solenoid valve connected to the electric circuit by the elevation free switch. 4. The lift control means according to claim 3, wherein the electric circuit operates by a first relay that operates in response to switching of the lift lever to a lowered position, and an ON operation of the lift free switch. Has a second relay,
The self-holding circuit is configured to energize the solenoids of the respective solenoid valves by the operation of the first and second relays, and to maintain the second relay in the operating state even when the lift free switch is turned off. Lift control means. 5. The lifting control means according to claim 4, wherein the hydraulic circuit is connected to a pressure switch that is turned on by detecting a hydraulic pressure applied when the lifting lever is switched to a lowered position, Elevation control means, wherein the first relay operates according to an ON state of the pressure switch. 6. The lift control means according to claim 3, wherein the electric circuit detects a hydraulic pressure applied when the lift lever is switched to the lowered position and is turned on, and the lift free switch. And a serially connected relay, and the solenoid of each of the solenoid valves is energized by the operation of the relay. 7. The elevating control means according to claim 4, wherein the electric circuit operates a confirmation member for informing a free fall of the elevating device by the operation of each of the relays. Lifting control means characterized by being a thing.