JP2000016149A - Elevation device for load table - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load table elevating device whereby the slow stopping range when a load-carrying platform is lowering to stop is made changeable in accordance with the height of the load-carrying platform. SOLUTION: A load-carrying platform elevating device of a motor-truck is configured so that a load-carrying platform is supported at the free end of a lift arm whose one end is supported on the loading space and a lift cylinder device 15 to elevate and lower the load-carrying platform is interposed between the loading space and the load-carrying platform and is equipped with a lift sensor 41 to sense the vertical position of the load-carrying platform and a grounding sensor 42 to sense grounding of the load-carrying platform, and the slow stop range of the lowering motion corresponding to the height of the loading space is set in conformity to the first sensing signal of the grounding sensor 42 and the sensing signal given by the lift sensor 41, and at the second lowering motion and thereafter a slow stop is generated in the set slow stop range. Even in case where the lowering stop position of the load table has varied with load variation or a height variation of the unloading place, the slow stop range of the lowering motion in accordance with the height of the loading space is set with the first lowering motion, so that it is possible to lessen the slow stop range and relieve the shock applied when the lowering of the load- carrying platform stops.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loading / unloading device and, more particularly, to a buffering technology when stopping the lowering operation of the loading device, for example, a technology effective for use in a loading / unloading device of a truck. .

[0002]

2. Description of the Related Art In order to facilitate the lifting and lowering of luggage with respect to a truck bed of a truck, there is a truck truck equipped with a loading tray lifting device on the truck. In general, a cradle lifting device of a lorry has a cradle rotatably supported at a free end of a lift arm having one end rotatably supported on the cradle. A tilt cylinder device that opens and closes the load receiving table is interposed therebetween, and a lift cylinder device that raises and lowers the load receiving table is provided therebetween, such that the tilt cylinder device and the lift cylinder device are operated by a hydraulic pump. It is configured.

[0003] Examples of this kind of conventional loading / unloading device lifting and lowering device are disclosed in Japanese Utility Model Laid-Open No. 3-63426 and Japanese Utility Model Laid-Open No. 1-69045.

[0004]

Generally, an impact is generated when the loading tray of the loading tray lifting device is started and stopped.
If the moving speed of the load receiving table is set to be slow to suppress this impact, the moving time of the load receiving table becomes longer, and the cargo handling work time becomes longer. Therefore, it is generally conceivable to control the moving speed of the loading tray to be slow only at the time of starting and stopping. However, in the truck loading and unloading device, the lower limit of the loading tray may be caused by the height of the load fluctuating due to the weight of the load, or the height of the loading / unloading place, such as the road surface and platform, changing in various ways. Is not uniform, it is difficult to control the moving speed of the loading tray to be slow in an appropriate range when the lowering operation of the loading tray by the lift cylinder device is stopped.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a lifting / lowering device capable of appropriately setting a gentle stop range when the lifting / lowering device stops the lowering of the loading tray in accordance with the height of the loading tray.

[0006]

According to a first aspect of the present invention, there is provided a loading / unloading device which includes a lift cylinder device for lifting and lowering the loading cradle between the loading pods. A lift sensor that detects the vertical position of the
A grounding sensor for detecting the grounding of the load receiving platform, wherein a slow stop range of a lowering operation corresponding to the height of the loading platform is set by an initial detection signal of the grounding sensor and a detection signal from the lift sensor. In the second and subsequent descending operations, the operation is gradually stopped within the set gentle stop range.

According to the above-described means, for example, even when the lowering stop position of the load receiving table changes due to a change in the weight of the load or the height of the loading / unloading place,
Since the slow stop range of the lowering operation corresponding to the height of the loading platform is set by the first lowering operation, it is possible to prevent the occurrence of an impact when the lowering of the load receiving platform is stopped without expanding the slow stop range.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a circuit diagram showing an apparatus for lifting and lowering a pallet truck according to an embodiment of the present invention. FIG.
Is a perspective view thereof. FIG. 3 is a block diagram of the main part. FIG. 4 is a flowchart at the time of opening operation of the loading tray, and FIG. 5 is a flowchart at the time of lowering operation of the loading tray. FIG.
FIG. 7 is an explanatory diagram for explaining a lowering operation of the loading tray.

In this embodiment, a loading tray lifting device 10 according to the present invention is installed at the rear end of a loading platform 2 of a truck 1 as shown in FIG. That is, the loading tray elevating device 10 includes a pair of lift arms 11 configured by a link mechanism (not shown).
11 is symmetrically arranged on the lower surface of the rear end side of the loading platform 2,
One end of each is rotatably supported. A load receiving table 12 is rotatably supported between the free ends of the two lift arms 11 and 11 so as to maintain the horizontal position. The loading tray 12 is made of a lightweight material having corrosion resistance and rigidity, such as aluminum, and is formed in a rectangular panel shape having a size corresponding to the loading tray 2. A cart stopper 1 is provided near an end of the upper surface of the loading table 12 opposite to the loading table 2.
3 are laid along the edge, and the cart stopper 1
Numeral 3 is configured to prevent a cart (not shown) placed on the receiving tray 12 from falling off.

[0010] A pair of tilt cylinder devices 14 for opening and closing the load receiving table are interposed between the lower surface of the rear end side of the load table 2 and the load side of the load receiving table 12 in a symmetrical manner. The cylinder devices 14 and 14 are configured to reciprocally rotate the load receiving table 12 between the vertical posture and the horizontal posture with respect to the lift arm 11. A pair of lift cylinder devices 15 for raising and lowering the load receiving table are interposed symmetrically between the lower surface of the rear end side of the load table 2 and the load side of the load receiving table 12. The devices 15, 15 are configured to raise and lower the loading tray 12 between the height position of the loading platform 2 and the ground position.

In this embodiment, as shown in FIG. 1, a single-acting hydraulic cylinder device is used for each of the tilt cylinder device 14 and the lift cylinder device 15 and is operated by a DC motor 16. It is configured to be operated by the hydraulic pump 17. A tank 18 is connected to the suction port side of the hydraulic pump 17,
A supply oil passage 19 connected to the discharge port of the hydraulic pump 17 has an oil passage to the tilt cylinder device 14 (hereinafter, referred to as tilt oil passage) 20 and an oil passage to the lift cylinder device 15 (hereinafter, lift oil passage). 21) are connected in parallel.

A control valve (hereinafter, referred to as a tilt valve) 22 for controlling the tilt cylinder device 14 is provided in the tilt oil passage 20, and a lift cylinder device 15 is provided in the lift oil passage 21. Control valve for controlling (hereinafter,
It is called a lift valve. ) 23 are interposed. Each of the tilt valve 22 and the lift valve 23 is composed of a two-port, two-position, spring offset, electromagnetic switching valve. A check valve 24 and a flow control valve 25 are provided in parallel with each other on the upstream side of the lift valve 23 in the lift oil passage 21.

A check valve 26 is interposed in the supply oil passage 19, and a discharge oil passage 27 is provided in the supply oil passage 19 with the hydraulic pump 1.
7 and the check valve 26. A control valve (hereinafter, referred to as a discharge valve) 28 for controlling a shortening operation of the tilt cylinder device 14 and the lift cylinder device 15 is provided in the discharge oil passage 27.
The discharge valve 28 is also constituted by a two-port, two-position, spring-offset electromagnetic switching valve. A flow control valve 2 is provided in the discharge oil passage 27 on the side of the tank 18 of the discharge valve 28.
9 are interposed. Between the supply oil passage 19 and the discharge oil passage 27, a relief valve 30 is provided with a hydraulic pump 17 of a check valve 26.
And the flow control valve 29 is connected to the tank 18 side.

An electric circuit 31 for driving the DC motor 16, an electric circuit for controlling the solenoid of the tilt valve 22 (hereinafter referred to as an electric circuit for tilt) 32, and a valve for lift 23.
An electric circuit (hereinafter, referred to as a lift electric circuit) 33 for controlling the solenoid of the controller 35 and an electric circuit (hereinafter, referred to as the discharge electric circuit) 34 for controlling the solenoid of the discharge valve 28 include a controller 35. Output terminals are connected respectively. The input terminal of the controller 35 has a switch (hereinafter, referred to as an open switch) 36 for instructing the opening operation of the loading tray 12 and a switch (hereinafter, a closing switch) for instructing the closing operation of the loading tray 12. 37, a switch (hereinafter, referred to as a lowering switch) for instructing a lowering operation of the load receiving tray 12, and a switch (hereinafter, referred to as an uppering switch) 39 for commanding the raising operation of the load receiving tray 12, respectively. It is connected.

An input end of the controller 35 is provided with the receiving tray 12.
(Hereinafter, referred to as a tilt sensor) 40, a sensor (hereinafter, referred to as a lift sensor) 41 for detecting a lift position of the load receiving table 12, and a load receiving table 12.
(Hereinafter, referred to as ground sensor)
42 are connected to each other. As shown in FIG. 2, the tilt sensor 40 is provided on the loading tray 12, and is configured to detect the opening angle of the loading tray 12 by measuring the inclination angle of the loading tray 12. The lift sensor 41 is provided on the lift arm 11, and is configured to detect the height position of the load receiving table 12 by detecting the rotation angle of the lift arm 11. The ground contact sensor 42 is interposed between the carrier 2 and the lift arm 11, and detects the ground by measuring the pressure between the carrier 2 and the lift arm 11 when the carrier 12 is grounded. It is configured.

As shown in FIG. 3, the controller 35 includes a horizontal judging circuit 43 and a slow start judging circuit 4 for tilt.
4, slow tilt determination circuit 45 for tilt, ground determination circuit 46,
Lift slow start determination circuit 47, lift slow stop determination circuit 48, ground position storage circuit 49, ground position selection circuit 50,
An initial determination circuit 51 is provided. The tilt sensor 40 is connected to a horizontal determination circuit 43, a slow start determination circuit 44 for tilt, and a slow stop determination circuit 45 for tilt. The lift sensor 41 is connected to a lift slow start determination circuit 47, a lift slow stop determination circuit 48, and a ground position storage circuit 49, and the ground sensor 42 is connected to a ground determination circuit 46. A sensor (hereinafter, referred to as a travel sensor) 5 for detecting travel of the truck 1 is provided at an input terminal of the first determination circuit 51.
2 is connected, and the output terminal of the first determination circuit 51 is connected to one input terminal of the ground position selection circuit 50. The other input terminal of the ground position selection circuit 50 has a ground position storage circuit 49.
The output terminal of the ground position selection circuit 50 is connected to the lift slow stop determination circuit 48.

Next, the loading / unloading device 1 according to the above configuration
The operation of 0 will be described with reference to a flowchart.

As shown in FIGS. 1 and 4, when the opening switch 36 is turned on by an operator to open the receiving table 12, the tilt valve 22 is opened and the discharge valve 28 is opened. The pressure oil in the hydraulic chamber of the tilt cylinder device 14 is supplied to a tilt valve 22, a discharge valve 28, and a flow control valve 29.
Is gradually discharged to the tank 18 via the valve, so that the tilt cylinder device 14 is gradually shortened. With the shortening of the tilt cylinder device 14, the loading tray 12 gradually opens. At this time, the tilt angle of the receiving table 12 is
, And is transmitted to the horizontal determination circuit 43, the tilt slow start determination circuit 44, and the tilt slow stop determination circuit 45.

In the preset initial slow start range in the opening operation of the loading table 12, the DC motor 16
Is driven at a very low speed by the drive electric circuit 31. Along with this low-speed operation, a small amount of pressure oil is supplied from the hydraulic pump 17 to the tilt oil passage 20 through the supply oil passage 19, so that the above-described shortened speed of the tilt cylinder device 14 becomes slower. Thereby, the impact at the time of starting the opening operation of the loading table 12 by the tilt cylinder device 14 is reduced.

When the predetermined range of the initial gentle trajectory ends, the DC motor 16 is stopped by the drive electric circuit 31. With this stop, the supply of a small amount of pressure oil to the tilt oil passage 20 is stopped, so that the tilt cylinder device 14
The above-mentioned shortening speed returns to the normal speed.

Thereafter, the DC motor 1 is moved within a predetermined final slow stop range in the opening operation of the loading tray 12.
6 is driven at a very low speed by the drive electric circuit 31. Along with this low speed operation, the hydraulic pump 17
, A small amount of pressure oil is supplied to the tilt oil passage 20, so that the above-described shortening of the tilt cylinder device 14 becomes slower. Thereby, the impact at the time of stopping the opening operation of the loading table 12 by the tilt cylinder device 14 is reduced.

Finally, when the loading table 12 reaches the horizontal position, the tilt valve 22 is closed, the DC motor 16 is stopped, and the discharge valve 28 is closed. When the tilt valve 22 is closed, the tilt cylinder device 14 is hydraulically held by the tilt valve 22, so that the horizontal state is maintained.

Next, when the lowering switch 38 is turned on by the operator to lower the loading tray 12, the lift valve 23 is opened and the discharge valve 28 is opened. Since the pressurized oil in the hydraulic chamber of the lift cylinder device 15 is gradually discharged to the tank 18 via the lift valve 23, the discharge valve 28, and the flow control valve 29, the lift cylinder device 15 is gradually shortened. . With the shortening of the lift cylinder device 15,
The receiving platform 12 gradually descends. At this time, the loading tray 12
The lift position is detected from time to time by the lift sensor 41 and transmitted to the ground position storage circuit 49, the lift slow start determination circuit 47, and the lift slow stop determination circuit 48.

In the range of the preset initial gentle start in the lowering operation of the loading table 12, the DC motor 16
Is driven at a very low speed by the drive electric circuit 31. Along with this low-speed operation, a small amount of pressurized oil is supplied from the hydraulic pump 17 to the lift oil passage 21 through the supply oil passage 19, so that the above-described shortened speed of the lift cylinder device 15 becomes slower. Thereby, the impact at the time of starting the lowering operation of the load receiving table 12 by the lift cylinder device 15 is reduced.

When the preset initial slow start range ends, the DC motor 16 is stopped by the drive electric circuit 31. With this stop, the supply of a small amount of pressure oil to the lift oil passage 21 is stopped, so that the lift cylinder device 15
The above-mentioned shortening speed returns to the normal speed.

On the other hand, the traveling sensor 52 shown in FIG.
The first determination circuit 51 determines whether or not it is the first time based on the measurement signal from
Is input to If the determination result is the first time, the contact position selection circuit 50 obtains the initial deceleration position (expressed by the distance from the upper limit of the loading tray) A by the following formula, and sends the result to the lift slow stop determination circuit 48. Send. A = H-α ...

Here, H is a standard vehicle height set in advance as shown in FIG.
Is equivalent to the lifting distance. α is a margin given to the standard vehicle height H because the lorry stops at an angle or the vehicle height changes depending on the load.

In the end slow stop range determined by the lift slow stop determination circuit 48 shown in FIG.
The DC motor 16 is operated at a very low speed by the drive electric circuit 31. Along with this low-speed operation, a small amount of pressurized oil is supplied from the hydraulic pump 17 to the lift oil passage 21 through the supply oil passage 19, so that the above-described shortened speed of the lift cylinder device 15 becomes slower. Thereby, the impact at the time of stopping the lowering operation of the loading table 12 by the lift cylinder device 15 is reduced.

When the receiving table 12 is grounded, the grounding sensor 42
The ground signal is detected by the ground detection circuit 46.
Sent to. When the ground determination circuit 46 determines that grounding is performed,
The ground position h (represented by the distance from the upper limit of the loading tray) is transmitted to the ground position storage circuit 49. Grounding position storage circuit 4
9 transmits the ground position h to the ground position selection circuit 50, and the ground position selection circuit 50 transmits a stop signal to the lift slow stop determination circuit 48. Then, the lift valve 23 is closed, the DC motor 16 is stopped, and the discharge valve 28 is closed. When the lift valve 23 is closed,
Since the lift cylinder device 15 is hydraulically held by the lift valve 23, the lift cylinder device 15 is in a state where the ground state is maintained.

Raise switch 39 to raise the receiving table 12
Is turned on by the operator, the lift valve 23 is opened, the discharge valve 28 is closed, the DC motor 16 is rotated by the drive electric circuit 31, and the hydraulic pump 17 is operated. Since the pressure oil of the hydraulic pump 17 is supplied to the lift cylinder device 15 via the lift valve 23, the lift cylinder device 15 extends. With the extension of the lift cylinder device 15, the loading tray 12 moves up. At this time, the lift position of the load receiving table 12 is detected every moment by the lift sensor 41 and transmitted to the ground position storage circuit 49, the slow start determination circuit 47 for lift and the slow stop determination circuit 48 for lift.

In a predetermined range of the initial gentle start in the raising operation of the loading table 12, the DC motor 16
Is operated at low speed by the drive electric circuit 31. With the low-speed operation, the supply amount of the pressurized oil from the hydraulic pump 17 to the lift cylinder device 15 is suppressed, so that the above-described extension speed of the lift cylinder device 15 becomes slower. Thereby, the impact at the time of starting the lifting operation of the load receiving table 12 by the lift cylinder device 15 is reduced.

When the preset initial slow start range ends, the DC motor 16 is driven at a normal rotation speed by the drive electric circuit 31. With the increase in the speed, the supply amount of the pressurized oil from the hydraulic pump 17 to the lift cylinder device 15 increases, so that the extension speed of the lift cylinder device 15 becomes a normal speed.

Thereafter, the DC motor 1 is moved within a predetermined final slow stop range in the lifting operation of the loading tray 12.
6 is operated at low speed by the drive electric circuit 31. With the low-speed operation, the supply amount of the pressurized oil from the hydraulic pump 17 to the lift cylinder device 15 is suppressed, so that the above-described extension speed of the lift cylinder device 15 becomes slower. Thereby, the impact when the lifting operation of the load receiving table 12 by the lift cylinder device 15 is stopped is reduced.

When the loading table 12 reaches the upper limit position, the lift valve 23 is closed and the DC motor 16 is stopped. When the lift valve 23 is closed, the lift cylinder device 15 is hydraulically held by the lift valve 23, so that the upper limit position is maintained.

When the lowering switch 38 is turned on again by the operator to lower the receiving tray 12, the lift valve 23 opens and the discharge valve 28 opens. Since the pressurized oil in the hydraulic chamber of the lift cylinder device 15 is gradually discharged to the tank 18 via the lift valve 23, the discharge valve 28, and the flow control valve 29, the lift cylinder device 15 is gradually shortened. . With the shortening of the lift cylinder device 15, the loading tray 12 gradually descends. At this time, the lift position of the load receiving table 12 is detected every moment by the lift sensor 41 and transmitted to the ground position storage circuit 49, the slow start determination circuit 47 for lift and the slow stop determination circuit 48 for lift.

In the range of the initial gentle start which is set in the lowering operation of the loading tray 12 again, the DC motor 1
6 is driven at a very low speed by the drive electric circuit 31. Along with this low speed operation, the hydraulic pump 17
, A small amount of pressure oil is supplied to the lift oil passage 21, so that the above-described shortening speed of the lift cylinder device 15 becomes slower. Thereby, the lift cylinder device 15
The impact at the time of starting the lowering operation of the loading tray 12 due to the above is alleviated.

When the preset initial slow start range ends, the DC motor 16 is stopped by the drive electric circuit 31. With this stop, the supply of a small amount of pressure oil to the lift oil passage 21 is stopped, so that the lift cylinder device 15
The above-mentioned shortening speed returns to the normal speed.

On the other hand, when the lowering switch 38 is turned on by the operator in order to lower the loading tray 12, the initial determination circuit 51 determines whether or not it is the first time based on the measurement signal from the traveling sensor 52 as shown in FIG. Is determined,
The determination result is input to the ground position selection circuit 50. Since the determination result is not the first time (the second time or later), the grounding position selection circuit 50 obtains the non-initial deceleration position B (expressed by the distance from the upper limit of the loading tray) by the following formula, and the result is obtained. Is transmitted to the lift slow stop determination circuit 48. B = h-β ...

Here, h is the ground position stored in the ground position storage circuit 49 as shown in FIG. β is the minimum deceleration distance (slow stop range) necessary for buffering the lowering operation of the loading table 12.

When the non-initial deceleration position B is determined by the lift slow stop determination circuit 48, the DC motor 16 is operated at a very low speed by the drive electric circuit 31. Along with this low-speed operation, a small amount of pressurized oil is supplied from the hydraulic pump 17 to the lift oil passage 21 through the supply oil passage 19, so that the above-described shortened speed of the lift cylinder device 15 becomes slower. Thereby, the impact at the time of stopping the lowering operation of the loading table 12 by the lift cylinder device 15 is reduced.

When the receiving table 12 is grounded, the grounding sensor 42
Thus, the ground position is detected, and a detection signal is transmitted to the ground determination circuit 46. When the grounding determination circuit 46 determines that the grounding is performed, the grounding position is transmitted to the grounding position storage circuit 49. The ground position storage circuit 49 transmits the ground to the ground position selection circuit 50, and the ground position selection circuit 50 stores the lift slow stop determination circuit 4
8 is sent a stop signal. Then, the lift valve 23 is closed, the DC motor 16 is stopped, and the discharge valve 28 is closed. When the lift valve 23 is closed, the lift cylinder device 15 is hydraulically held by the lift valve 23, so that the ground state is maintained.

When the operator turns on the lift switch 39 again to raise the receiving tray 12, the lift valve 23 is opened, the discharge valve 28 is closed, the DC motor 16 is rotated by the drive electric circuit 31, and the hydraulic pump is turned on. 1
7 is driven. The hydraulic oil of the hydraulic pump 17 is the lift valve 2
3, the lift cylinder device 15 is extended because it is supplied to the lift cylinder device 15. With the extension of the lift cylinder device 15, the loading tray 12 moves up. At this time, the lift position of the loading tray 12 is detected every moment by the lift sensor 41, and the horizontal determination circuit 43
The signal is transmitted to the slow start determination circuit 47 for lift and the slow stop determination circuit 48 for lift.

The DC motor 16 is also driven at a low speed by the drive electric circuit 31 even in the preset initial gentle start-up range in the lifting operation of the loading tray 12 again.
With the low-speed operation, the supply amount of the pressurized oil from the hydraulic pump 17 to the lift cylinder device 15 is suppressed, so that the above-described extension speed of the lift cylinder device 15 becomes slower. Thereby, the lift cylinder device 1
The shock at the start of the lifting operation of the load receiving table 12 due to 5 is reduced.

When the preset initial slow start range ends, the DC motor 16 is driven by the drive electric circuit 31 at a normal rotation speed. With the increase in the speed, the supply amount of the pressurized oil from the hydraulic pump 17 to the lift cylinder device 15 increases, so that the extension speed of the lift cylinder device 15 becomes a normal speed.

Thereafter, the DC motor 1 is moved within the preset final slow stop range in the lifting operation of the loading table 12.
6 is operated at low speed by the drive electric circuit 31. With the low-speed operation, the supply amount of the pressurized oil from the hydraulic pump 17 to the lift cylinder device 15 is suppressed, so that the above-described extension speed of the lift cylinder device 15 becomes slower. Thereby, the impact when the lifting operation of the load receiving table 12 by the lift cylinder device 15 is stopped is reduced.

Finally, when the loading table 12 reaches the upper limit position, the lift valve 23 is closed and the DC motor 16 is stopped. When the lift valve 23 is closed, the lift cylinder device 15 is hydraulically held by the lift valve 23, so that the upper limit position is maintained.

Thereafter, the lowering operation of the load receiving table 12 is repeated again, so that the operation of lowering the load on the load table 2 is repeatedly performed.

When the unloading operation of the desired load is completed and the close switch 37 is turned on by the operator to close the load receiving table 12, the tilt valve 22 is opened and
The discharge valve 28 is closed, and the DC motor 16
1 to operate the hydraulic pump 17. Since the pressure oil of the hydraulic pump 17 is supplied to the tilt cylinder device 14 via the tilt valve 22, the tilt cylinder device 14 extends. With the extension of the tilt cylinder device 14, the receiving table 12 is closed. At this time, the loading tray 12
The tilt angle is detected from time to time by the tilt sensor 40 and transmitted to the horizontal determination circuit 43, the tilt slow start determination circuit 44, and the tilt slow stop determination circuit 45.

In the range of the preset initial gentle start in the closing operation of the loading table 12, the DC motor 16
Is operated at low speed by the drive electric circuit 31. With the low-speed operation, the supply amount of the pressure oil from the hydraulic pump 17 to the tilt cylinder device 14 is suppressed, so that the extension speed of the tilt cylinder device 14 becomes slower by that amount. Thereby, the impact at the time of starting the closing operation of the loading table 12 by the tilt cylinder device 14 is reduced.

When the preset range of the initial slow start is completed, the DC motor 16 is operated at a normal rotation speed by the drive electric circuit 31. With the increase in the speed, the supply amount of the pressurized oil from the hydraulic pump 17 to the tilt cylinder device 14 increases, so that the extension speed of the tilt cylinder device 14 becomes a normal speed.

Thereafter, the DC motor 1 is moved within a predetermined final slow stop range in the closing operation of the loading tray 12.
6 is operated at low speed by the drive electric circuit 31. Since the supply amount of the pressure oil from the hydraulic pump 17 to the tilt cylinder device 14 is suppressed, the tilt cylinder device 1
The extension speed of No. 4 becomes slower. Thereby, the impact when the closing operation of the loading table 12 by the tilt cylinder device 14 is stopped is reduced.

Finally, when the receiving table 12 reaches the closed position, the tilt valve 22 is closed and the DC motor 16 is stopped. When the tilt valve 22 is closed, the tilt cylinder device 14 is hydraulically held by the tilt valve 22, so that the closed position is maintained.

As described above, according to the present embodiment, the deceleration range (slow stop range) can be set in accordance with the actual unloading surface when stopping in the lowering operation of the loading table by the lift cylinder device. Therefore, it is possible to appropriately mitigate the impact at the time of the unloading operation of the loading tray without extending the unloading operation time.

Further, since the operation speed can be automatically reduced at the beginning and end of the opening / closing operation and the elevating operation of the loading tray, it is possible to safely carry out the lifting and lowering of the luggage while eliminating the troublesome operation of the operator. it can. In addition, since the operation speed is reduced by the deceleration operation of the motor, the hydraulic circuits of the tilt cylinder device and the lift cylinder device do not need to be changed.

It should be noted that the present invention is not limited to the above-described embodiment, but may be modified without departing from the scope of the invention.
It goes without saying that various changes can be made.

For example, the deceleration control of the lift cylinder device is not limited to be executed by the deceleration operation of the motor, but may be executed by hydraulic control by a flow control valve or the like.

In the above description, the type in which the receiving tray 12 is rotated to lift the receiving tray 12 is described. However, the present invention is applicable to a case in which the receiving tray is vertically lifted.

The controller is not limited to an electric circuit, but may be a microcomputer.

It is desirable that the configurations and mounting positions of the tilt sensor, the lift sensor, the grounding sensor, and the travel sensor are appropriately selected in accordance with the conditions of the loading / unloading device.

[0060]

As described above, according to the present invention,
Since the deceleration range can be set according to the actual unloading surface when stopping the unloading operation by the lift cylinder device, the impact of the unloading operation can be appropriately adjusted without extending the unloading time. Can be eased.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a lifting / lowering device of a pallet truck according to an embodiment of the present invention.

FIG. 2 is a perspective view thereof.

FIG. 3 is a block diagram of a main part thereof.

FIG. 4 is a flowchart at the time of an opening operation of a loading tray.

FIG. 5 is a flowchart at the time of a lowering operation of a loading tray.

FIG. 6 is an explanatory diagram for explaining a lowering operation of the loading tray.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Lorry car, 2 ... Carrier, 10 ... Lifting device for cargo carrier, 1
DESCRIPTION OF SYMBOLS 1 ... Lift arm, 12 ... Loading stand, 13 ... Cart stopper, 14 ... Tilt cylinder device, 15 ... Lift cylinder device, 16 ... DC motor, 17 ... Hydraulic pump, 18 ... Tank, 19 ... Supply oil path, 20 ... Tilt Oil passage, 21: lift oil passage, 22: tilt valve, 23: lift valve, 2
4: Check valve, 25: Flow control valve, 26: Check valve, 2
7 ... discharge oil passage, 28 ... discharge valve, 29 ... flow control valve, 3
0 ... relief valve, 31 ... drive electric circuit, 32 ... tilt electric circuit, 33 ... lift electric circuit, 34 ... discharge electric circuit, 35 ... controller, 36 ... open switch, 37
... Close switch, 38 ... Down switch, 39 ... Up switch, 40 ... Tilt sensor, 41 ... Lift sensor, 42
... Grounding sensor, 43 ... Horizontal determination circuit, 44 ... Tilt slow start determination circuit, 45 ... Tilt slow stop determination circuit, 46 ...
Grounding judgment circuit, 47 ... Lift slow start judgment circuit, 48 ...
Lift slow stop determination circuit, 49 ... ground position storage circuit, 5
0: ground position selection circuit, 51: initial determination circuit, 52: travel sensor.

Claims (3)

[Claims] 1. A loading cradle lifting / lowering device provided with a lift cylinder device for raising and lowering a loading cradle between a loading platform and a loading cradle, comprising: a lift sensor for detecting a vertical position of the loading cradle; A grounding sensor for detecting grounding, wherein a first stop signal of the lowering operation corresponding to the height of the carrier is set by a first detection signal of the grounding sensor and a detection signal from the lift sensor, In a subsequent lowering operation, the loading tray lifting device is slowly stopped with a set slow stop range. 2. The lifting platform according to claim 1, wherein said loading platform is rotatably supported by a free end of a lift arm whose one end is rotatably supported by said loading platform. apparatus. 3. The lifting device according to claim 1, wherein the loading table is supported by the loading table so as to be able to move up and down.