JP7003624B2 - lift device - Google Patents

Description

The present invention relates to an elevating device for moving an object to be elevated in the vertical direction by a plurality of jacks.

Conventionally, as this type of elevating device, a plurality of hydraulic jacks that support an object to be elevated, a hydraulic pump that supplies hydraulic oil to each jack, and hydraulic oil that is discharged from the hydraulic pump and supplied to each jack. A pump pump having a hydraulic pressure adjusting valve for adjusting the hydraulic pressure and a length detecting means for detecting the expansion and contraction length of each jack is known (see, for example, Patent Document 1).

This elevating device controls to synchronize the expansion / contraction operation of each jack based on the expansion / contraction length of each of the plurality of jacks detected by the length detecting means.

Japanese Unexamined Patent Publication No. 10-236786

In the elevating device, it is determined that a defect has occurred when the expansion / contraction lengths of the plurality of jacks detected by the length detecting means differ by a predetermined value or more, and the spool of the flow rate adjusting valve is operated to operate each jack. Is stopped.

In the elevating device, the hydraulic pump is continuously driven even when the spool of the flow rate adjusting valve is operated to stop each jack. Therefore, in the elevating device, if the operation of the spool of the flow rate adjusting valve is hindered by foreign matter mixed in the hydraulic circuit, even if the spool is operated to stop the expansion / contraction operation of each jack, the operation of each jack is actually performed. A state in which the expansion / contraction operation is not stopped may occur. In this case, in the elevating device, the difference in the expansion / contraction length of each jack becomes larger, and there is a possibility that the members constituting the elevating device may be damaged or the elevating device may tip over.

An object of the present invention is to provide an elevating device capable of reliably stopping the expansion / contraction operation of each of a plurality of jacks in the event of a malfunction.

In the present invention, in order to achieve the above object, a plurality of hydraulic jacks that support an object to be lifted, a hydraulic pump that supplies hydraulic oil to each jack, and a hydraulic pump that is discharged from the hydraulic pump and supplied to each jack. It is equipped with a switching valve that switches whether to regulate the flow of hydraulic oil, and is a lifting device that raises or lowers the object to be lifted by the expansion and contraction operation of multiple jacks, and is a jack that detects the expansion and contraction length of each jack. Pump stop means for stopping the hydraulic pump when the difference between the expansion and contraction lengths of the jacks obtained from the expansion and contraction lengths of the jacks detected by the length detecting means and the jack length detecting means is equal to or more than the first predetermined value. And, when the difference in the expansion / contraction length of each jack obtained from the expansion / contraction length of each jack detected by the jack length detecting means is smaller than the first predetermined value and is greater than or equal to the second predetermined value and less than the first predetermined value. It is provided with a jack stopping means that regulates the flow of hydraulic oil discharged from a hydraulic pump by a switching valve and is supplied to each jack to stop each jack.

As a result, each jack stops the expansion / contraction operation by stopping the hydraulic pump. Therefore, after the expansion / contraction operation of each jack is stopped by the jack stopping means, the difference in the expansion / contraction length of each jack becomes large. In addition, the pump stopping means can reliably stop the expansion and contraction operation of each jack.

According to the present invention, after the expansion / contraction operation of each jack is stopped by the jack stopping means, when the difference in the expansion / contraction length of each jack becomes large, the expansion / contraction operation of each jack is surely stopped by the pump stopping means. Therefore, it is possible to suppress damage to the members constituting the elevating device and overturning of the elevating device.

It is a figure which looked at from the rear of the elevating device which shows one Embodiment of this invention. It is the figure which looked at the elevating device from the left side. It is a schematic block diagram of a hydraulic pressure supply circuit. It is a block diagram which shows the control system. It is a flowchart of the elevating operation control process. It is a flowchart of a pump stop state release process.

1 to 6 show an embodiment of the present invention. In the present embodiment, the upper direction of FIG. 1 is the upper direction, the lower direction of FIG. 1 is the lower direction, the right direction of FIG. 1 is the right, the left direction of FIG. 1 is the left, and the front direction of FIG. 1 is the rear. And, the back direction of FIG. 1 is expressed as the front.

The elevating device 1 of the present invention is a hydraulic gate-type lifter capable of lifting an elevating object T such as a large press machine or a machine tool and moving it in the horizontal direction.

As shown in FIGS. 1 and 2, the elevating device 1 is provided on four jacks 10 arranged in the front-rear direction on both sides of the elevating object T in the width direction and above the four jacks 10, and the elevating object T is provided. It includes a support mechanism 20 for supporting, four jacks 10, and a traveling device 30 for moving the support mechanism 20 in the front-rear direction.

Each of the four jacks 10 has a telescopic expansion / contraction mechanism. Each jack 10 has five square tubular jack members of a base jack 11, a second jack 12, a third jack 13, a force jack 14, and a top jack 15.

Further, each jack 10 has a second jack cylinder 16 for moving the second jack 12 with respect to the base jack 11, and a third jack cylinder 17 for moving the third jack 13 with respect to the second jack 12. It has a force jack cylinder 18 for moving the force jack 14 with respect to the third jack 13, and a top jack cylinder 19 for moving the top jack 15 with respect to the force jack 14.
Each of the cylinders 16, 17, 18 and 19 has an extension side inlet for flowing hydraulic oil into the cylinder tube during the extension operation and a reduction side inlet for allowing the hydraulic oil to flow into the cylinder tube during the reduction operation. is doing.

The support mechanism 20 includes a pair of front-rear main beams 21 extending in the width direction, a pair of width-direction sub-beams 22 extending in the front-rear direction between the pair of main beams 21, and a center portion of each of the pair of sub-beams 22 in the front-rear direction. It is provided with a hook 23 provided on the lower surface.

One of the pair of main beams 21 connects between the upper end of the top jack 15 of the front and left jacks 10 and the upper end of the top jack 15 of the front and right jacks 10. The other of the pair of main beams 21 connects between the upper end of the top jack 15 of the rear and left jack 10 and the upper end of the top jack 15 of the rear and right jack 10.

The pair of sub-beams 22 are provided so as to be movable in the width direction with respect to the pair of front and rear main beams 21. Further, the pair of sub-beams 22 are moved in the width direction by the sub-beam cylinders 24 provided on both the front and rear sides of the sub-beams 22.
The sub-beam cylinder 24 has an extension side inlet that allows hydraulic oil to flow into the cylinder tube during the extension operation, and a reduction side inlet that allows hydraulic oil to flow into the cylinder tube during the reduction operation.

The traveling device 30 includes a traveling frame 31 for connecting the base ends of the base jacks 11 of jacks 10 adjacent to each other in the front-rear direction on both sides in the width direction, and a pair of front and rear wheel units 32 provided at the lower part of the traveling frame 31. ,have. The wheel unit 32 is driven by a traveling electric motor 33 to move the four jacks 10 and the support mechanism 20 in the front-rear direction.

The second jack cylinder 16, the third jack cylinder 17, the force jack cylinder 18, the top jack cylinder 19, and one of the four sub-beam cylinders 24, which corresponds to one jack 10, are adjacent to each other. It is connected to one hydraulic pressure supply circuit 40, and expands and contracts with hydraulic oil flowing through the hydraulic pressure supply circuit 40.

As shown in FIG. 3, the hydraulic supply circuit 40 discharges hydraulic oil to be supplied to the second jack cylinder 16, the third jack cylinder 17, the force jack cylinder 18, the top jack cylinder 19, and the sub-beam cylinder 24. A switching valve for adjusting the flow direction and flow rate of the hydraulic oil between the pump 41, the hydraulic oil tank 42 for storing the hydraulic oil discharged by the hydraulic pump 41, and the hydraulic pump 41 and the second jack cylinder 16. Second jack control valve 43, third jack control valve 44 as a switching valve for adjusting the flow direction and flow rate of hydraulic oil between the hydraulic pump 41 and the third jack cylinder 17, and the hydraulic pump 41. The force jack control valve 45 as a switching valve for adjusting the flow direction and flow rate of the hydraulic oil between the force jack cylinder 18 and the hydraulic oil between the hydraulic pump 41 and the top jack cylinder 19. The control valve 46 for the top jack as a switching valve for adjusting the flow direction and the flow rate, and the control valve 47 for the sub beam for adjusting the flow direction and the flow rate of the hydraulic oil between the hydraulic pump 41 and the sub beam cylinder 24. And, in the state where the spools of the control valves 43, 44, 45, 46, 47 (hereinafter referred to as 43 to 47) are in the neutral position, the hydraulic oil discharged from the hydraulic pump 41 is returned to the hydraulic oil tank 42. It has an unload valve 48 as a switching valve.
In the present embodiment, the control valves 43 to 47 capable of adjusting the flow rate of the hydraulic oil are used, but a solenoid valve having no function of adjusting the flow rate of the hydraulic oil may be used.

The hydraulic pump 41 is driven by the electric motor 41a for the pump, sucks the hydraulic oil stored in the hydraulic oil tank 42 from the suction port, and discharges it from the discharge port.

Each control valve 43 to 46 is a 4-way 4-port 3-position solenoid valve. The control valves 43 to 46 regulate the inflow of hydraulic oil from each port when the spool is in the neutral position.

The subbeam control valve 47 is a 4-way 4-port 3-position solenoid valve. The subbeam control valve 47 regulates the inflow of hydraulic oil from the T port in the neutral position of the spool, and communicates the T port, the A port, and the B port with each other.

The unload valve 48 is a 4-way 4-port 3-position solenoid valve. The unload valve 48 communicates each port with the spool in the neutral position.

Each of the control valves 43 to 46, the sub-beam control valve 47, and the unload valve 48 has a function (neutral position detecting means) of transmitting a signal to the controller 50 described later at the neutral position of the spool.

Here, the circuit configuration of the hydraulic pressure supply circuit 40 will be specifically described.

The suction side of the hydraulic pump 41 is connected to the hydraulic oil tank 42. On the discharge side of the hydraulic pump 41, the P ports of the control valves 43 to 47 and the unload valve 48 are connected in parallel to each other.
Further, the T ports of the control valves 43 to 47 and the unload valve 48 are connected to the hydraulic oil tank 42 in parallel with each other.
The A port and the B port of each of the control valves 43 to 47 are connected to the extension side inlet or the reduction side inlet of each cylinder 16 to 19, 24, respectively.
The A port of the unload valve 48 is connected to the hydraulic oil tank 42 via the relief valve 40a whose relief pressure is the first predetermined pressure during the extension operation of each jack 10. Further, the B port of the unload valve 48 is connected to the hydraulic oil tank 42 via a relief valve 40b having a second predetermined pressure whose relief pressure is smaller than the first predetermined pressure during the reduction operation of the jack 10.

Further, as shown in FIG. 4, the elevating device 1 includes a controller 50 for controlling the operation of each jack 10. The controller 50 has a CPU, ROM, RAM, and the like. When the controller 50 receives an input signal from a device connected to the input side, the CPU reads the program stored in the ROM based on the input signal, and also stores the state detected by the input signal in the RAM. It sends an output signal to a device connected to the output side.

On the input side of the controller 50, as shown in FIG. 4, the operation setting input unit 51 for the operator to input the operation and setting of the elevating device 1 and the expansion / contraction length of each of the four jacks 10 are detected. A jack length detector 52-1, 52-2, 52-3, 52-4 (hereinafter referred to as 52-1 to 4) as a jack length detecting means for the purpose is connected.

The jack length detectors 52-1 to 5-4 include a reel, a wire wound around the reel, and an encoder for detecting the rotation direction and the number of rotations of the reel. In the jack length detectors 52-1 to 4, the reel is attached to the base jack 11, the tip of the wire is fixed to the tip of the top jack 15, and the length of the wire unwound by the extension operation of the jack 10 is detected by the encoder. By doing so, the expansion / contraction length of the jack 10 is detected.

On the output side of the controller 50, as shown in FIG. 4, a traveling electric motor 33, a pump electric motor 41a, and a control valve 43-1 for a second jack provided in each hydraulic pressure supply circuit 40 of the four jacks 10. , 43-2, 43-3, 43-4 (hereinafter referred to as 43-1 to 4), Control valve for third jack 44-1, 44-2, 44-3, 44-4 (hereinafter referred to as 44-). 1 to 4), force jack control valves 45-1, 45-2, 45-3, 45-4 (hereinafter referred to as 45-1 to 4), top jack control valves 46-1, 46-2, 46-3, 46-4 (hereinafter referred to as 46-1 to 4), control valves for subbeams 47-1, 47-2, 47-3, 47-4 (hereinafter referred to as 47-1 to 47-1). 4) and unload valves 48-1, 48-2, 48-3, 48-4 (hereinafter referred to as 48-1 to 4) are connected.

In the elevating device 1 configured as described above, an elevating operation for moving the elevating object T in the vertical direction will be described.

First, the four jacks 10, the support mechanism 20, and the traveling device 30 of the elevating device 1 are driven to position the hook 23 above the elevating object T placed on the floor surface.

Next, using a connecting member such as an eyebolt attached to the elevating object T, the elevating object T and the hook 23 are connected by a wire rope, and the four jacks 10 are extended to lift the elevating object T.

The elevating object T lifted by the hook 23 can be moved in the front-rear direction by driving the traveling device 30, and the four jacks 10 are reduced at the target positions in the front-rear direction to move the elevating object T. Place it on the floor or a predetermined mounting surface.

Further, during the elevating operation by the four jacks 10 of the elevating device 1, the controller 50 performs the elevating operation control process for controlling the expansion / contraction operation of the four jacks 10. The operation of the controller 50 at this time will be described with reference to the flowchart of FIG.

(Step S1)
In step S1, the CPU determines whether or not the jack 10 is in the ascending / descending operation. If it is determined that the elevating operation is in progress, the process is transferred to step S2, and if it is not determined that the elevating operation is in progress, the elevating operation control process is terminated.

(Step S2)
When it is determined in step S1 that the ascending / descending operation is in progress, the CPU determines the height of the upper end portion of the top jack 15 of each jack 10 based on the detection results of the jack length detectors 52-1 to 4 in step S2. get.

(Step S3)
In step S3, the CPU has a first predetermined value D1 (for example, D1 =) in which the difference D between the heights of the highest jack 10 and the lowest jack 10 among the heights of the upper ends of the four jacks 10 acquired in step S2 is It is determined whether or not it is 100 mm) or more. If it is determined that the difference D is equal to or greater than the first predetermined value D1, the process is transferred to step S4, and if it is not determined that the difference D is equal to or greater than the first predetermined value D1, the process is transferred to step S6.
Here, the fact that the difference D is equal to or greater than the first predetermined value D1 means that the control valves 43-1 to 4,44-1 to 4,45-1 to 4 are used to stop the ascending / descending operation of the four jacks 10 described later. , 46-1 to 4 and the unload valves 48-1 to 4 are operated, which means that the raising and lowering operation of the jack 10 is continued. In this state, the hydraulic oil is in the flow path of the hydraulic oil of any of the control valves 43-1 to 4,44-1 to 4,45-1 to 4,46-1 to 4 and the unload valves 48-1 to 4. It is determined that the foreign matter mixed in the oil is clogged and the foreign matter clogged in the flow path of the hydraulic oil hinders the movement of the spool.

(Step S4)
When it is determined in step S3 that the difference D in height between the highest jack 10 and the lowest jack 10 is equal to or greater than the first predetermined value D1, the CPU stops the hydraulic pump 41 in step S4 (pump stopping means). , Move the process to step S5.
Here, the hydraulic pump 41 cuts off the energization of the electric motor 41a for the pump that drives the hydraulic pump 41, and controls the rotation number so that the rotation number of the electric motor 41a for the pump becomes zero. Will stop the drive.

(Step S5)
In step S5, the CPU stops driving the traveling device 30 and ends the elevating operation control process.
Here, the traveling device 30 is stopped by stopping the driving of the traveling electric motor 33.

(Step S6)
If it is not determined in step S3 that the height difference D between the highest jack 10 and the lowest jack 10 is equal to or greater than the first predetermined value D1, the CPU in step S6 determines that the highest jack 10 and the lowest jack 10 are the lowest. It is determined whether or not the difference D in height is equal to or greater than the second predetermined value D2 (D1> D2, for example, D2 = 60 mm), which is smaller than the first predetermined value D1. If it is determined that the difference D is equal to or greater than the second predetermined value D2, the process is transferred to step S7, and if it is not determined that the difference D is equal to or greater than the second predetermined value D2, the process is transferred to step S8.
Here, the fact that the difference D is the second predetermined value D2 or more means that the control for adjusting the operation of the four jacks is controlled in order to reduce the height difference D between the highest jack 10 and the lowest jack 10, which will be described later. It means that the difference D is large even though it is done.

(Step S7)
When it is determined in step S6 that the difference D in height between the highest jack 10 and the lowest jack 10 is equal to or greater than the second predetermined value D2, in step S7, the CPU determines that the control valves 43-1 to 4 for the second jack, Control valves 44-1 to 4 for third jacks, control valves 45-1 to 4 for force jacks, control valves 46-1 to 4 for top jacks, and unload valves 48-1 to 4 are operated to operate four jacks 10. The operation is stopped (jack stop means), and the ascending / descending operation control process is terminated.
In this state, the operator can reduce the height difference D between the highest jack 10 and the lowest jack 10 by operating each jack individually, and can restart the raising and lowering operation of the jacks.

(Step S8)
If it is not determined in step S6 that the height difference D between the highest jack 10 and the lowest jack 10 is equal to or greater than the second predetermined value D2, the CPU in step S8 determines that the highest jack 10 and the lowest jack 10 are the lowest. It is determined whether or not the difference D in height is equal to or greater than the third predetermined value D3 (D1>D2> D3, for example, 30 mm), which is smaller than the first predetermined value D1 and the second predetermined value D2. If it is determined that the difference D is the third predetermined value D3 or more, the process is transferred to step S9, and if it is not determined that the difference D is the third predetermined value D3 or more, the process is transferred to step S12.

(Step S9)
If it is determined in step S8 that the height difference D between the highest jack 10 and the lowest jack 10 is equal to or greater than the third predetermined value D3, in step S9, the CPU determines whether the four jacks 10 are in the ascending operation. Judge whether or not. If it is determined that the four jacks 10 are in the ascending operation, the process is transferred to step S10, and if it is not determined that the four jacks 10 are in the ascending operation, the process is transferred to step S11.

(Step S10)
When it is determined in step S9 that the four jacks 10 are in the ascending operation, the CPU stops the extension operation of the highest jack 10 in step S10 and shifts the processing to step S12.

(Step S11)
When it is determined in step S9 that the four jacks 10 are in the descending operation, the CPU stops the reduction operation of the lowest jack 10 in step S11 and shifts the processing to step S12.

(Step S12)
In step S12, the CPU determines whether or not the difference D in height between the highest jack 10 and the lowest jack 10 is less than the fourth predetermined value D4 (D1>D2>D3> D4, for example, 10 mm). If it is determined that the difference D is less than the fourth predetermined value D4, the process is transferred to step S13, and if it is not determined that the difference D is less than the fourth predetermined value D4, the process is returned to step S9.

(Step S13)
When it is determined in step S12 that the height difference D between the highest jack 10 and the lowest jack 10 is less than the fourth predetermined value D4, the CPU restarts the driving of the stopped jack 10 in step S13.

(Step S14)
In step S14, the CPU determines whether or not an operation for stopping the ascending / descending operation has been performed on the operation setting input unit 51. When it is determined that the operation for stopping the elevating operation has been performed on the operation setting input unit 51, the elevating operation control process is terminated and the operation for stopping the elevating operation is performed on the operation setting input unit 51. If it is not determined, the process is returned to step S2.

Further, when the hydraulic pump 41 is stopped in step S4 of the elevating operation control process, the controller 50 performs a pump stop state release process for releasing the stop state of the hydraulic pump 41. The operation of the controller 50 at this time will be described with reference to the flowchart of FIG.

(Step S21)
In step S21, the CPU determines whether or not the hydraulic pump 41 is rotating based on step S4 of the elevating operation control process. When it is determined that the hydraulic pump 41 is rotating based on step S4 of the elevating operation control process, that is, when it is not determined that the hydraulic pump 41 is stopped, the pump stop state release process is terminated. If it is not determined that the hydraulic pump 41 is rotating based on step S4 of the elevating operation control process, that is, if it is determined that the hydraulic pump 41 is stopped, the process is transferred to step S22.

(Step S22)
When it is determined in step S21 that the hydraulic pump 41 is stopped based on step S4 of the elevating operation control process, in step S22, the CPU causes the operation setting input unit 51 to stop the hydraulic pump 41 by the operator. Determine whether or not the operation to be released has been input. If it is determined that the operation for releasing the stopped state of the hydraulic pump 41 has been input, the process is transferred to step S23, and if it is not determined that the operation for releasing the stopped state of the hydraulic pump 41 has been input, the pump is pumped. The stop state release process is terminated.

(Step S23)
When it is determined in step S22 that the operation for releasing the stopped state of the hydraulic pump 41 has been input, in step S23, the CPU uses the control valves 43-1 to 4 for the second jack and the control valves 44-1 to 4 for the third jack. , Control valves 45-1 to 4 for force jacks, control valves 46-1 to 4 for top jacks, and unload valves 48-1 to 4 are moved to repeatedly switch the flow path of hydraulic oil. Valve state recovery means) is performed.
Here, the valve state recovery operation of the control valves 43-1 to 4,44-1 to 4,45-1 to 4,46-1 to 4 and the unload valves 48-1 to 4 is performed in the flow path of the hydraulic oil. This is an operation of repeatedly moving the spool to switch the flow path of the hydraulic oil in order to discharge the clogged foreign matter from the flow path of the hydraulic oil.

(Step S24)
In step S24, the CPU determines whether the spool positions of the control valves 43-1 to 4,44-1 to 4,45-1 to 4,46-1 to 4 and the unload valves 48-1 to 4 are in the neutral position. Determine if not. If it is determined that the spool position is in the neutral position, the process is transferred to step S25, and if it is not determined that the spool position is in the neutral position, the pump stop state release process is terminated.
That is, if it is not determined that the position of the spool is the neutral position, the pump stop state is not released, so that the redrive of the hydraulic pump 41 is restricted (redrive regulation means).

(Step S25)
In step S25, the CPU releases the stopped state of the hydraulic pump 41 and ends the pump stop state release process.
In this state, the operator can restart the driving of the hydraulic pump 41 and operate each jack 10 individually.

As described above, according to the elevating device of the present embodiment, when the difference D in height between the highest jack 10 and the lowest jack 10 is the second predetermined value D2 or more and less than the first predetermined value D1, the control valve 43 -1 to 4,44-1 to 4,45-1 to 4,46-1 to 4 and unload valves 48-1 to 4 provide a second jack cylinder 16 for each jack 10, a third jack cylinder 17, and a force jack. The cylinder 18 for the top jack and the cylinder 19 for the top jack are stopped, and the hydraulic pump 41 is stopped when the difference D in height between the highest jack 10 and the lowest jack 10 is equal to or greater than the first predetermined value D1.

As a result, after the expansion and contraction operation of each jack 10 is stopped by the control valves 43-1 to 4,44-1 to 4,45-1 to 4,46-1 to 4 and the unload valves 48-1 to 4, the expansion and contraction operation of each jack 10 is stopped. When the difference D in the expansion / contraction lengths of the jacks 10 becomes large, the hydraulic pump 41 can be stopped to reliably stop the expansion / contraction operation of the jacks 10, so that the elevating device 1 is configured. It is possible to suppress damage to the members and overturning of the elevating device 1.

Further, after the hydraulic pump 41 is stopped, when the hydraulic pump 41 is restarted, the control valves 43-1 to 4,44-1 to 4,45-1 to 4,46-1 to 4 and the unload valves 48-1 to Valve state recovery to recover the state of control valves 43-1 to 4,44-1 to 4,45-1 to 4,46-1 to 4 and unload valves 48-1 to 4 by moving the spool of 4. It is working.

As a result, the clogging of the control valves 43-1 to 4,44-1 to 4,45-1 to 4,46-1 to 4 and the unload valves 48-1 to 4 causes the expansion and contraction operation of each jack 10. If it is the cause of the stop, the valve state recovery operation is performed to clear the clogging of foreign matter in each valve, and after the hydraulic pump 41 is stopped, the hydraulic pump 41 is driven again to raise and lower each jack. Can be continued.

Further, the spools of the control valves 43-1 to 4,44-1 to 4,45-1 to 4,46-1 to 4 and the unload valves 48-1 to 4 are moved to control valves 43-1 to 4, After recovering the state of 44-1 to 4,45-1 to 4,46-1 to 4 and the unload valve 48-1 to 4, the control valves 43-1 to 4,44-1 to 4,45 When the neutral positions of -1 to 4,46-1 to 4 and the unload valves 48-1 to 4 are not detected, the redrive of the hydraulic pump 41 is restricted.

As a result, the jack 10 in a state where the clogging of the control valves 43-1 to 4,44-1 to 4,45-1 to 4,46-1 to 4 and the unload valves 48-1 to 4 is not cleared. It is possible to prevent the resumption of the ascending / descending operation and improve the safety.

Further, the hydraulic pump 41 is driven by the power of the electric motor 41a for the pump, and the hydraulic pump 41 stops the drive by cutting off the energization of the electric motor 41a for the pump.

As a result, when the hydraulic pump 41 is stopped, the electric motor 41a for the pump as a drive source is stopped, so that the hydraulic pump 41 can be reliably driven while avoiding a state in which the hydraulic pump 41 is erroneously continued to be driven. It is possible to stop it.

In the above embodiment, the object T to be lifted and lowered is supported by four jacks 10 and moved in the vertical direction, but the present invention is not limited to this. The number of jacks that support the object to be lifted and lowered may be two or more.

Further, in the above embodiment, the hydraulic pump 41 is driven by the electric motor 41a for a pump, but the present invention is not limited to this. The hydraulic pump may be driven by the power of the engine. When the hydraulic pump is driven by the power of the engine, the hydraulic pump may be stopped by stopping the engine.

Further, in the above embodiment, the hydraulic pump 41 is stopped by stopping the drive of the electric pump 41a, but the hydraulic pump and the electric motor for the pump are connected via a clutch. If so, the clutch may be used to cut off the transmission of the power of the electric pump motor to the hydraulic pump. However, for the purpose of stopping the hydraulic pump, it is more reliable to stop the electric motor for the pump than to stop the clutch.

1 ... Elevating device, 10 ... Jack, 16 ... Cylinder for second jack, 17 ... Cylinder for third jack, 18 ... Cylinder for force jack, 19 ... Cylinder for top jack, 41 ... Hydraulic pump, 41a ... Electric motor for pump, 43 ... control valve for second jack, 44 ... control valve for third jack, 45 ... control valve for force jack, 46 ... control valve for top jack, 48 ... unload valve, 50 ... controller, 52-1-4 ... jack length detection vessel.

Claims (5)

Switch between multiple hydraulic jacks that support the object to be lifted, a hydraulic pump that supplies hydraulic oil to each jack, and whether to regulate the flow of hydraulic oil discharged from the hydraulic pump and supplied to each jack. A lifting device equipped with a switching valve that raises or lowers an object to be lifted by expanding and contracting a plurality of jacks.
Jack length detecting means for detecting the expansion and contraction length of each jack,
A controller that controls the hydraulic pump and the switching valve based on the difference in the expansion / contraction length of each jack obtained from the expansion / contraction length of each jack detected by the jack length detecting means is provided.
The controller is
When the difference in the expansion / contraction length of each jack is equal to or greater than the first predetermined value, the hydraulic pump is stopped .
When the difference in the expansion and contraction length of each jack is smaller than the first predetermined value and is greater than or equal to the second predetermined value and less than the first predetermined value, the flow of hydraulic oil by the switching valve is restricted and all jacks are stopped. Ru
lift device. The controller is
When the difference in the expansion / contraction length of each jack is smaller than the second predetermined value and is greater than or equal to the third predetermined value and less than the second predetermined value, until the difference in the expansion / contraction length of each jack becomes the fourth predetermined value. Stop the tallest or lowest jack of each jack
The elevating device according to claim 1. The controller is
After the hydraulic pump is stopped by the pump stop means, when the hydraulic pump is restarted, the spool of the switching valve is moved to restore the state of the switching valve.
The elevating device according to claim 1 or 2 . The controller is
Regulate the re-drive of the hydraulic pump when the neutral position of the switching valve is not detected after moving the spool of the switching valve.
The elevating device according to claim 3 . The hydraulic pump is driven by the power of an electric motor.
The elevating device according to any one of claims 1 to 4 , wherein the controller stops the hydraulic pump by cutting off the energization of the electric motor.

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