JP2003267673A - Cargo deck lifting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the efficiency of the cargo lifting work of a cargo deck lifting device. <P>SOLUTION: The cargo deck lifting device 10 has left and right lift valves 28 and 26 for controlling left and right lift cylinder devices 15L and 15R for lifting a lift arm 11 to which the cargo deck 12 is rotatably journaled, and left and right tilt valves 27 and 25 for controlling left and right tilt cylinder devices 14L and 14R for rotating the cargo deck 12. A speed increasing valve 29 is connected to the left lift valve 28 and the left tilt valve 27. The speed increasing valve 29 is structured to connect the left lift valve 28 and the left tilt valve 27 to a tank 18 via a tank oil path 47 when the cargo deck 12 is opened/closed or when no load is applied. Accordingly, as only the right tilt cylinder device or the right lift cylinder device is operated by switching the speed increasing valve when the cargo deck is opened/closed or when no load is applied to increase the speed, the redundant time in the work of the cargo deck lifting device is reduced and the efficiency of the cargo lifting work is improved. <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 a loading platform raising / lowering device, and more particularly to a technique for improving the work efficiency of loading / unloading work, and for example, it is used for a loading / unloading platform raising / lowering device for loading / unloading a luggage to / from a cargo carrier. And about effective technology.

[0002]

2. Description of the Related Art In order to facilitate loading and unloading of cargo onto and from a cargo carrier, a cargo carrier lifting device installed at a rear portion of a cargo carrier is a lift whose one end is rotatably supported by the cargo carrier. A load receiving table is rotatably supported on a free end of the arm, and a tilt cylinder device for opening and closing the load receiving table and a lift cylinder device for moving the load receiving table up and down are interposed between the load table and the load receiving table. Since a large actuating force is required to raise and lower the load receiving tray with a load placed thereon, the tilt cylinder device and the lift cylinder device are provided in pairs on the left and right.

[0003]

However, in the conventional load receiving platform raising / lowering device, even if the load receiving platform is opened / closed or operated in an unloaded state in which no load is placed on the load receiving platform, a pair of left and right units is used. Since the tilt cylinder device and the pair of left and right lift cylinder devices operate, the opening / closing operation speed and the ascending / descending speed of the cargo receiving stand become slow, and as a result, the efficiency of the work of loading and unloading the cargo to and from the cargo carrier lowers. There is a point.

SUMMARY OF THE INVENTION An object of the present invention is to provide a loading platform raising / lowering device which can improve the efficiency of lifting and lowering of loads.

[0005]

[Means for Solving the Problems] A first means for solving the problems is a pair of lift cylinder devices for raising and lowering a lift member which rotatably supports a load carrier at one end.
In a cargo tray elevating device comprising a pair of tilt cylinder devices for rotating the cargo tray, an oil passage to one tilt cylinder device of the pair of tilt cylinder devices is a tank when the cargo tray is opened and closed. It is characterized in that it is configured to be connected to an oil passage.

According to the above-mentioned first means, since the pressure acts on only one of the pair of tilt cylinder devices when the load receiving tray is opened and closed, the open / close speed of the load receiving tray can be increased. Since the loading and unloading work period is a play period for loading and unloading work, the work efficiency of the entire loading and unloading work by the loading and unloading device can be improved by shortening the play period. .

A second means for solving the problem is to raise or lower the load receiving table so that an oil passage to one lift cylinder device of the pair of lift cylinder devices and a load to the load receiving table are provided. It is characterized in that it is configured to be connected to the tank oil passage when it is not loaded and without a load.

According to the above-mentioned second means, the pressure oil is supplied to only one lift cylinder device of the lift cylinder device or the discharge control is performed when no load is loaded on the load receiving table. Since the other lift cylinder device is directly released to the tank, the lifting speed of the load receiving platform is increased.

A third means for solving the problem is that the oil passage to one tilt cylinder device of the pair of tilt cylinder devices is connected to the tank oil passage when the cargo tray is opened and closed, and An oil passage to one lift cylinder device of the pair of lift cylinder devices is configured to be connected to a tank oil passage when no load is loaded on the load receiving table.

According to the above-mentioned third means, the speed is doubled not only when opening and closing the load receiving tray but also when lifting up or down the load receiving tray, so that the work efficiency of raising and lowering the load is greatly enhanced. Improve to.

A fourth means for solving the problem is, in addition to the above-mentioned third means, stopping the loading tray during the lift-up or lifting-down of the loading tray so that the tip portion of the loading tray is about ±. It is characterized in that the oil passage of one of the tilt cylinder devices of the tilt cylinder device is connected to the tank oil passage even when the tilt is raised or lowered to perform the swinging motion within a range of 10 degrees.

According to the above-mentioned fourth means, in addition to the above-mentioned third means, since only one of the tilt cylinder devices operates at the time of tilting up or tilting down, it is possible to speed up the operation of the load receiving tray. .

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

In the present embodiment, the loading platform raising / lowering device according to the present invention is installed at the rear end of the loading platform 2 of the truck 1 as shown in FIG. That is, the load receiving platform elevating device 10 includes a pair of left and right lift arms 11L and 11R as lift members.
1L and 11R are symmetrically arranged at the rear end of the loading platform 2, and one end of each is rotatably supported. A load receiving table 12 is rotatably supported between the free ends of the left and right lift arms 11L and 11R. The loading tray 12 is made of a material having corrosion resistance and rigidity such as aluminum or iron, and is formed into a rectangular panel shape having a size corresponding to the loading tray 2. A cart stopper 13 is laid along the rear edge of the upper surface of the cargo receiving tray 12 near the edge opposite to the cargo tray 2 (hereinafter referred to as the rear edge). It is configured to prevent the loaded cart from falling out.

A pair of left and right tilt cylinder devices 14L and 14R for opening and closing the cargo carrier 12 is provided between the lower surface of the rear end of the cargo carrier 2 and the front edge of the cargo carrier 12 which is the cargo carrier side edge.
Are symmetrically interposed, and both tilt cylinder devices 14L and 14R are operated by opening / closing switches.
The load carrier 12 is configured to reciprocally rotate between a vertical posture and a horizontal posture with the support shafts of the left and right lift arms 11L and 11R as rotation centers. Further, the left and right tilt cylinder devices 14L and 14R operate the tilt lowering switch or the tilt raising switch to swing the tip of the cargo receiving tray 12 in a horizontal position within a range of about ± 10 degrees. It is designed for easy grounding of the platform of the receiving platform and the ground.

A pair of left and right lift cylinder devices 15L for raising and lowering the cargo carrier 12 are provided between the lower surface of the rear end side of the luggage carrier 2 and the rear ends of the left and right lift arms 11L, 11R.
The left and right lift arms 1 and 15R are provided symmetrically with each other.
By rotating 1L and 11R around the support shaft on the side of the loading platform 2 as a rotation center, the loading platform 12 is moved up and down between the height position of the loading platform 2 and the grounding position.

Next, the hydraulic circuit and the control circuit will be described.

As shown in FIG. 2, left and right tilt cylinder devices 14L and 14R and left and right lift cylinder devices 15L and 15R are both single-acting hydraulic cylinder devices. Left and right tilt cylinder device 1
4L and 14R operate so as to close the load receiving base 12 by the pressure oil supplied from the hydraulic pump 17 operated by the DC motor 16. In addition, the left and right lift cylinder devices 1
5L and 15R are loaded by the pressure oil of the hydraulic pump 17 on the load receiving base 12
Operate to raise. When the load receiving tray 12 is opened, the pressure oil supplied to the left and right tilt cylinder devices 14L and 14R is discharged by the elastic force of the return springs 14La and 14Ra built in them, so that it can be opened. In addition, when lowering the cargo receiving tray 12, the left and right lift cylinder devices 15L, 15R
The pressure oil supplied to the load receiving tray 12 is discharged by its own weight to lower the pressure oil.

The intake port of the hydraulic pump 17 has a tank 1
8 is connected, and the main oil passage 19 connected to the discharge port of the hydraulic pump 17 has an oil passage 20 to the right tilt cylinder device 14R and an oil passage to the right lift cylinder device 15R at a branch point 19a. 21 and an oil passage (hereinafter referred to as a left oil passage) 22 to the left tilt cylinder device 14L and the left lift cylinder device 15L.
Further, the left oil passage 22 is branched at a branch point 22a into an oil passage 23 to the left tilt cylinder device 14L and an oil passage 24 to the left lift cylinder device 15L.

Oil path 2 to the right tilt cylinder device 14R
A control valve (hereinafter referred to as a right tilt valve) 25 for controlling the expansion and contraction of the right tilt cylinder device 14R is provided at 0, and the right is provided in the oil passage 21 to the right lift cylinder device 15R. A control valve (hereinafter, referred to as a right lift valve) 26 for controlling expansion and contraction of the lift cylinder device 15R is interposed. In the oil path 23 to the left tilt cylinder device 14L, a control valve (hereinafter, referred to as a left tilt valve) 27 for controlling the expansion and contraction of the left tilt cylinder device 14L.
And a control valve (hereinafter, referred to as a left lift valve) 2 for controlling expansion and contraction of the left lift cylinder device 15L in the oil passage 24 to the left lift cylinder device 15L.
8 is installed. The right tilt valve 25, the right lift valve 26, the left tilt valve 27, and the left lift valve 28 are all configured by 2 ports / 2 positions / spring offset / electromagnetic switching valve.

In the present embodiment, a control valve (hereinafter referred to as a control valve) for executing a control for accelerating the speed in the left oil passage 22 when opening and closing the load receiving tray or when operating in a no-load state where no load is placed on the load receiving tray. , A speed-up valve). The speed increasing valve 29 is composed of two ports, two positions, a spring offset, and an electromagnetic switching valve. Normally, the load port A is connected to the pump port P, but at the time of switching to increase the speed, the load port is connected. It is set to connect A to the tank port T.

A control valve (hereinafter referred to as a lowering valve) 30 and a check valve 31 are provided in series in the main oil passage 19. A discharge oil passage 32 is connected to the main oil passage 19 so as to bypass the hydraulic pump 17 and the check valve 31. A first spool valve (hereinafter, referred to as a first discharge valve) 33 and a second spool valve (hereinafter, referred to as a second discharge valve) 34 are provided in the discharge oil passage 32 in series with each other. The first discharge valve 33 and the second discharge valve 34 are shortening operations of the left and right tilt cylinder devices 14L and 14R and the left and right lift cylinder devices 15L and 15R, that is, the operation of opening the load receiving base 12 by the return springs 14La and 14Ra and the load receiving base 12. Is configured to control the operation of descending by its own weight. A relief oil passage 35 is branched from the middle of the main oil passage 19 between the hydraulic pump 17 and the check valve 31 and connected to the discharge oil passage 32, and a relief valve 36 is provided in the middle of the relief oil passage 35. Has been done. A pressure switch 37 is connected between the branch point 19a and the lowering valve 30, and the pressure switch 37 is connected to the control circuit of the solenoid of the speed increasing valve 29 so that the pressure in the main oil passage 19 is predetermined. If it is lower than the value, it is turned on. Incidentally, in the present embodiment, the predetermined value is about 2942k.
It is set to Pa (30 kgf / cm ² ).

3 and 4 show ten types of control circuits for the solenoid. FIG. 3A shows a control circuit in the case of opening the load receiving table, in which the opening switch 41 includes the solenoid 29s of the speed increasing valve 29, the solenoid 25s of the right tilt valve 25, the solenoid 27s of the left tilt valve 27, and The solenoids 30s of the lowering valve 30 are connected in series. The hydraulic circuit of FIG. 3 (a) is shown in FIG.

FIG. 3B shows a control circuit for lowering the load receiving tray when no load is placed on the load receiving tray. The lowering switch 42 is the solenoid 29 of the speed increasing valve 29.
s, the solenoid 26s of the right lift valve 26, the solenoid 28s of the left lift valve 28, and the solenoid 30s of the lowering valve 30 are connected in series, and
The pressure switch 37 is connected in series between the lowering switch 42 and the solenoid 29s of the speed increasing valve 29. Figure 3
The hydraulic circuit of (b) is shown in FIG. Figure 3 (b ')
Shows a control circuit for lowering the load receiving tray while the load is placed on the load receiving tray.
Solenoid 28s and solenoid 3 for lowering valve 30
0s respectively. However, pressure switch 3
Since 7 is off, the solenoid 29s of the speed increasing valve 29 does not operate. The hydraulic circuit of FIG. 3 (b ') is shown in FIG.

FIG. 3 (c) shows a case where the tip of the load receiving tray is lowered by a swinging operation within a range of about ± 10 degrees when no load is placed on the load receiving tray. The tilt lowering switch 43 is the solenoid 29 of the speed increasing valve 29.
s, the solenoid 25s of the right tilt valve 25, the solenoid 27s of the left tilt valve 27, and the solenoid 30s of the lowering valve 30 are respectively connected in series, and
The pressure switch 37 is connected in series between the tilt lowering switch 43 and the solenoid 29s of the speed increasing valve 29. The hydraulic circuit of FIG. 3 (c) is shown in FIG. Figure 3
(C ') shows the case where the tilt is lowered while the luggage is placed on the receiving tray. Tilt down switch 43
Are connected in series to the solenoid 25s of the right tilt valve 25, the solenoid 27s of the left tilt valve 27, and the solenoid 30s of the lowering valve 30. However, since the pressure switch 37 is off, the solenoid 29s of the speed increasing valve 29 does not operate. The hydraulic circuit of FIG. 3 (c ') is shown in FIG.

In contrast to FIG. 3A, FIG.
The control circuit when closing 2 is shown. In FIG. 4D, the closing switch 46 is connected in series to the solenoid 29s of the speed increasing valve 29, the solenoid 25s of the right tilt valve 25, and the solenoid 27s of the left tilt valve 27, respectively. The hydraulic circuit of FIG. 4 (d) is shown in FIG.

FIG. 4 (e) shows a case where the load receiving tray is lifted while no load is placed on the load receiving tray. In FIG. 4 (e), the raising switch 45 is the speed increasing valve 29.
29s of right, solenoid 2 of right lift valve 26
6s, the solenoid 28s of the left lift valve 28 is connected in series, and the pressure switch 37 is connected in series between the raising switch 45 and the solenoid 29s of the speed increasing valve 29. The hydraulic circuit of FIG. 4 (e) is shown in FIG. FIG. 4 (e ') shows a case where the cargo cradle is lifted in a state where the cargo is loaded on the cargo cradle.
The lift switch 45 is the solenoid 26 of the right lift valve 26.
s and the solenoid 28s of the left lift valve 28 are connected in series. However, since the pressure switch 37 is off, the solenoid 29s of the speed increasing valve 29 does not operate. The hydraulic circuit of FIG. 4 (e ') is shown in FIG.

FIG. 4 (f) shows a case where the load is not placed on the load receiving platform and the tip of the load receiving platform is lifted by a swinging motion within a range of about ± 10 degrees. The tilt up switch 44 is connected in series to the solenoid 29s of the speed increasing valve 29, the solenoid 25s of the right tilt valve 25, and the solenoid 27s of the left tilt valve 27, and the pressure switch 37 is connected to the tilt up switch 44. Acceleration valve 2
It is connected in series with 9 solenoids 29s.
The hydraulic circuit of FIG. 4 (f) is shown in FIG. Figure 4
(F ') shows a case where the tip of the load receiving tray is lifted by a swinging motion within a range of about ± 10 degrees with the load placed on the load receiving tray. The tilt up switch 44 is connected in series to the solenoid 25s of the right tilt valve 25 and the solenoid 27s of the left tilt valve 27, respectively. However,
Since the pressure switch 37 is off, the speed increasing valve 2
The solenoid 29s of 9 does not operate. The hydraulic circuit of FIG. 4 (f ') is shown in FIG.

Next, the loading platform elevating / lowering device 1 having the above configuration.
The operation of 0 will be described. Normally, in a state in which the cargo carrier 12 is vertically stored at the rear of the cargo carrier 2 of the truck 1, the right tilt cylinder device 14R in the hydraulic circuit of FIG.
The right lift cylinder device 15R is filled with pressure oil supplied from the hydraulic pump 17, and the left tilt cylinder device 14L and the left lift cylinder device 15L suck up from the tank 18 as the cylinder devices extend. The oil is filled.

In FIG. 3 (a), when the opening switch 41 is operated, the solenoid 29s of the speed increasing valve 29, the solenoid 25s of the right tilt valve 25, the solenoid 27s of the left tilt valve 27 and the lowering valve 30. Solenoid 30
Each s is excited and switched as shown in FIG.

Then, the pressure oil inside the right tilt cylinder device 14R is discharged by the resilience of the return spring 14Ra built into the right tilt cylinder device 14R and the weight of the load receiving base 12, and the right tilt valve is used. 25, the lowering valve 30, the first discharge valve 33, and the second discharge valve 34 are returned to the tank 18, so that the right tilt cylinder device 14R is shortened. On the other hand, the pressure oil inside the left tilt cylinder device 14L causes the left tilt cylinder device 14L to
Return spring 14La and cargo receiving stand 12 built in
Is discharged by its own weight and returned to the tank 18 via the left tilt valve 27, the speed increasing valve 29 and the tank oil passage 47, so that the left tilt cylinder device 14L is also shortened at the same time. However, the pressure oil inside the left tilt cylinder device 14L bypasses the first discharge valve 33 and the second discharge valve 34 and is returned directly to the tank 18, so that the cargo table 1
The speed of the opening operation of 2 becomes faster accordingly.

The opening switch 41 of the load receiving tray 12 can be operated only when the load receiving tray 12 is stopped at the upper limit, and cannot be operated at the position where the load receiving tray 12 is lowered from the upper limit. Is configured.

FIG. 3B shows the case where the load receiving tray 12 is lowered when there is no load on the load receiving tray 12. When the lowering switch 42 is operated, the solenoid 2 of the right lift valve 26
6s, the solenoid 28s of the left lift valve 28 and the solenoid 30s of the lowering valve 30 are excited and switched as shown in FIG. At this time, when no load is placed on the load receiving table 12 and no load is applied, as shown in FIG.
Since 7 is set to be normally closed, the solenoid 29s of the speed increasing valve 29 is excited and switched.

By switching between these, the pressure oil inside the right lift cylinder device 15R is discharged by the weight of the load receiving table 12, and the right lift valve 26, the lowering valve 30, the first discharging valve 33 and the second valve. Tank 1 via drain valve 34
Since it is returned to 8, the right lift cylinder device 15R is shortened. On the other hand, the pressure oil inside the left lift cylinder device 15L is discharged by its own weight of the load receiving table 12 and returned to the tank 18 via the left lift valve 28, the speed increasing valve 29 and the tank oil passage 47. The left lift cylinder device 15L is also shortened at the same time. However, since the pressure oil inside the left lift cylinder device 15L bypasses the first discharge valve 33 and the second discharge valve 34 and is directly returned to the tank 18, the speed of the lowering operation of the load receiving table 12 is reduced. That will be faster.

FIG. 3 (b ') shows a case where the load receiving tray 12 is lowered while the load is placed on the load receiving tray 12. Down switch 4
2 is operated, the solenoid 26 of the right lift valve 26
s, the solenoid 28 s of the left lift valve 28 and the solenoid 30 s of the lowering valve 30 are excited, respectively.
Are switched as shown in FIG. Also, the receiving stand 1
Due to the increase in the weight of the second load, the pressure in the main oil passage 19 increases and the pressure switch 37 is turned off, so that the speed increasing valve 29 is returned to the non-excitation position. As a result, the pressure oil inside the left lift cylinder device 15L passes through the oil passage 24 to the left lift cylinder device and the left oil passage 22 to the main oil passage 19
Then, it joins the pressure oil discharged from the right lift cylinder device 15R and is returned to the tank 18 via the discharge oil passage 32. Therefore, the discharge time of the pressure oil is delayed.

FIG. 3 (c) shows that there is no load on the load receiving tray 12 and the tip of the load receiving tray 12 is about ± 1 while the load receiving tray 12 is being lowered.
This is the case of lowering by a swinging motion in the range of 0 degree. When the tilt down switch 43 is closed, the right tilt valve 2
The solenoid 25s for No. 5, the solenoid 27s for the left tilt valve 27, and the solenoid 30s for the lowering valve 30 are excited and switched as shown in FIG. At this time, when no load is placed on the load receiving table 12 and no load is applied, as shown in FIG.
Since the pressure switch 37 is set to be normally closed, the solenoid 29s of the speed increasing valve 29 is excited and switched.

Then, the pressure oil inside the right tilt cylinder device 14R is discharged by the own weight of the load receiving base 12 and the elastic force of the return spring 14Ra built into the right tilt cylinder device 14R, and the right tilt valve is discharged. 25, the lowering valve 30, the first discharge valve 33, and the second discharge valve 34 are returned to the tank 18, so that the right tilt cylinder device 14R is shortened. On the other hand, the pressure oil inside the left tilt cylinder device 14L is the weight of the load receiving table 12 and the return spring 1 built in the left tilt cylinder device 14L.
4 La and is discharged to the tank 18 via the left tilt valve 27, the speed increasing valve 29 and the tank oil passage 47, the left tilt cylinder device 14L is also shortened at the same time. By the shortening operation of the right tilt cylinder device 14R and the left tilt cylinder device 14L, the load receiving tray 1
2 is tilted down. At this time, since the pressure oil inside the left tilt cylinder device 14L bypasses the first discharge valve 33 and the second discharge valve 34 and is directly returned to the tank 18, the swinging operation of the neck 12 of the load carrier 12 is performed. The speed of will increase accordingly.

After the luggage is placed on the receiving tray 12,
In FIG. 3 (c '), when the tilt lowering switch 43 is closed, the solenoid 25s of the right tilt valve 25, the solenoid 27s of the left tilt valve 27 and the solenoid 30s of the lowering valve 30 are excited, respectively. Are switched as shown in FIG. At this time, the pressure of the main oil passage 19 rises because the load is placed on the load receiving table 12, so that the pressure switch 37 opens in FIG. 3 (c '). Therefore, the solenoid 29 of the speed increasing valve 29 is
s remains demagnetized.

As a result, the right tilt cylinder device 14
The pressure oil inside R is discharged by the weight of the load receiving table 12, the weight of the load, and the elastic force of the return spring 14Ra built in the right tilt cylinder device 14R, and the right tilt valve 25 and the oil passage 20 are discharged. Since the oil is returned to the tank 18 via the main oil passage 19, the lowering valve 30, the first discharge valve 33, and the second discharge valve 34, the right tilt cylinder device 14R is shortened. On the other hand, the left tilt cylinder device 14L
The pressure oil inside is also discharged by the weight of the load receiving table 12, the weight of the load, and the return spring 14La built in the left tilt cylinder device 14L. At this time, the receiving tray 12
The pressure on the main oil passage 19 increases due to the load placed on the pressure switch 37, and the pressure switch 37 opens. Therefore, the solenoid 29s of the speed increasing valve 29 remains demagnetized, and the pressure oil of the tilt cylinder device 14L is transferred from the oil passage 23 to the left tilt cylinder device to the speed increasing valve 29 and the left oil passage 22.
Through the main oil passage 19. Therefore, the oil discharged from the two tilt cylinder devices 14R and 14L is merged with the single main oil discharge passage 19 and discharged.
The tilt lowering operation of is slowed down.

After the luggage is placed on the receiving tray 12,
In FIG. 4 (f '), when the tilt raising switch 44 is closed, the solenoid 25s of the right tilt valve 25 and the solenoid 27s of the left tilt valve 27 are excited and switched as shown in FIG. To be At this time, the pressure of the main oil passage 19 increases due to the load placed on the load receiving table 12, so that the pressure switch 37 is opened in FIG. 4 (f '). Therefore, the solenoid 29s of the speed increasing valve 29 remains demagnetized.

As a result, the right tilt cylinder device 14
The pressure oil inside R is discharged by the weight of the load receiving table 12, the weight of the load, and the elastic force of the return spring 14Ra built in the right tilt cylinder device 14R, and the right tilt valve 25 and the oil passage 20 are discharged. Since the oil is returned to the tank 18 via the main oil passage 19, the lowering valve 30, the first discharge valve 33, and the second discharge valve 34, the right tilt cylinder device 14R is shortened. On the other hand, the left tilt cylinder device 14L
The pressure oil inside is also discharged by the weight of the load receiving table 12, the weight of the load, and the return spring 14La built in the left tilt cylinder device 14L. At this time, the receiving tray 12
The pressure on the main oil passage 19 increases due to the load placed on the pressure switch 37, and the pressure switch 37 opens. Therefore, the solenoid 29s of the speed increasing valve 29 remains demagnetized, and the pressure oil of the tilt cylinder device 14L is transferred from the oil passage 23 to the left tilt cylinder device to the speed increasing valve 29 and the left oil passage 22.
Through the main oil passage 19. Therefore, the oil discharged from the two tilt cylinder devices 14R and 14L is merged with the single main oil discharge passage 19 and discharged.
The tilt lowering operation of is slowed down.

When the tilt raising switch 44 is closed in FIG. 4 (f) when no load is placed on the load receiving tray 12, the solenoid 25s of the right tilt valve 25 and the solenoid 27s of the left tilt valve 27 are closed. Are respectively excited and switched as shown in FIG. Then, the pressure oil from the hydraulic pump 17 is supplied to the right tilt cylinder device 14R via the main oil passage 19 and the oil passage 20 to the right tilt cylinder device. But,
Since no cargo is placed on the cargo receiving tray 12, the hydraulic pressure in the main oil passage 19 does not rise to a predetermined value.
The pressure switch is closed. Therefore, the solenoid of the speed increasing valve 29 is excited and switched, and the tank port T and the load port A are connected. The tank oil passage 4 is provided in the cylinder of the left tilt cylinder device 14L.
The oil in the tank 18 is sucked up via 7.

Next, a case will be described in which a load is placed on the load receiving table 12 and lifted. In FIG. 4 (e ′),
When the raising switch 45 is closed, the solenoid 26s of the right lift valve 26 and the solenoid 28s of the left lift valve 28 are excited and switched as shown in FIG. At this time, since the load is placed on the load receiving table 12, the pressure in the main oil passage 19 exceeds a predetermined value, so that the pressure switch 37 opens in FIG. 4 (e ′). Therefore, the solenoid 2 of the speed increasing valve 29
9s remains demagnetized.

As a result, the pressure oil from the hydraulic pump 17 is supplied to the right lift cylinder device 15R via the main oil passage 19 and the right lift valve 26, and the pressure oil from the hydraulic pump 17 is left. Is supplied to the lift cylinder device 15L through the main oil passage 19, the left oil passage 22, the speed increasing valve 29, and the left lift valve 28. Therefore, the right lift cylinder device 15R and the left lift cylinder device 15L are At the same time, the extension operation is performed. This left and right lift cylinder device 1
Due to the extension operation of 5L and 15R, even if a load is placed on the load receiving table 12, it can be powerfully raised. However, since the pressure oil from the hydraulic pump 17 is distributed to the left and right lift cylinder devices 15L and 15R, the speed of the ascending operation is halved compared to the case where only the right lift cylinder device 15R is supplied.

Next, a case will be described in which the cargo is lifted without loading the cargo on the cargo receiving tray 12. In FIG. 4 (e),
When the raising switch 45 is closed, the solenoid 26s of the right lift valve 26 and the solenoid 28s of the left lift valve 28 are excited and switched as shown in FIG. At this time, since no load is placed on the load receiving table 12, the pressure in the main oil passage 19 does not exceed a predetermined value. Therefore, the pressure switch 37 of FIG. 4E is closed, the solenoid 29s of the speed increasing valve 29 is also excited and switched, and the tank port T and the load port A are connected. Then, the oil in the tank 18 is sucked up into the cylinder of the left lift cylinder device via the tank oil passage 47.

When the closing switch 46 is closed in FIG. 4 (d) after the work of raising and lowering the luggage to and from the luggage carrier 2 is completed, the solenoid 29 of the speed increasing valve 29 is closed.
s, the solenoid 25s of the right tilt valve 25 and the solenoid 27s of the left tilt valve 27 are excited and switched as shown in FIG.

As a result, the pressure oil from the hydraulic pump 17 is supplied to the right tilt cylinder device 14R via the main oil passage 19 and the right tilt valve 25, so that the right tilt cylinder device 14R is extended. . On the other hand, the speed increasing valve 29
The tilt cylinder device 1 on the left side has been switched.
The oil stored in the tank 18 is sucked up into the 4L through the speed increasing valve 29 and the left tilt valve 27 as the cylinder extends, and the load carrier 12 only supplies the pressure oil to the right tilt cylinder device 14R. Will close and operate. Therefore, the speed of the closing operation of the cargo tray 12 is correspondingly increased.

The present invention is not limited to the above-mentioned embodiments, and within the scope of the invention,
It goes without saying that various changes can be made.

For example, the construction is not limited to shortening the expansion / contraction operation period of the lift cylinder device when no load is applied.
You may comprise so that only the opening / closing operation period of a tilt cylinder device may be shortened.

Not only the unloaded state and the loaded state of the loading tray are detected by the pressure switch for detecting the pressure of the main oil passage, but the tilt sensor for detecting the tilt of the loading tray or the loading tray is installed in the loading tray. You may comprise so that it may detect with a load sensor etc.

The solenoid of the speed-up valve is not limited to being demagnetized by an open / close switch, an up / down switch, and a tilt switch, but may be demagnetized by a microcomputer.

The lift member is not limited to a lift arm whose one end is rotatably supported, but may be an elevator or the like supported at the rear end of the loading platform so as to be lifted and lowered.

[0053]

As described above, according to the present invention,
Since it is possible to shorten the time required to open and close the loading tray,
The efficiency of lifting and lowering luggage can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing a load receiving platform elevating device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a hydraulic circuit of the load receiving platform lifting device.

FIG. 3 is a control circuit diagram of a solenoid for opening, lowering, and lowering a tilt of the cargo receiving table.

FIG. 4 is a control circuit diagram of a solenoid for closing, raising and tilting the cargo receiving tray.

FIG. 5 is a hydraulic circuit diagram corresponding to FIG. 3A when the opening switch 41 is turned on.

FIG. 6 is a view of the lower switch 42 on (without luggage).
It is a hydraulic circuit diagram corresponding to (b).

FIG. 7: FIG. 3 with the lower switch 42 on (with luggage)
It is a hydraulic circuit diagram corresponding to (b ').

FIG. 8 is a hydraulic circuit diagram corresponding to FIG. 3C when the tilt lowering switch 43 is turned on (without luggage).

FIG. 9 is a hydraulic circuit diagram corresponding to FIG. 3 (c ′) when the tilt lowering switch 43 is on (with luggage).

FIG. 10 is a hydraulic circuit diagram corresponding to FIG. 4 (f ′) when the tilt up switch 44 is on (with luggage).

FIG. 11 is a hydraulic circuit diagram corresponding to FIG. 4 (f) with the tilt-up switch 44 turned on (without luggage).

FIG. 12: FIG. 4 of the raising switch 45 on (with luggage)
It is a hydraulic circuit diagram corresponding to (e ').

FIG. 13: FIG. 4 with the raising switch 45 on (without luggage)
It is a hydraulic circuit diagram corresponding to (e).

FIG. 14 is a hydraulic circuit diagram corresponding to FIG. 4D with the closing switch 46 turned on.

[Explanation of symbols]

1 ... freight car, 2 ... luggage carrier, 10 ... cargo carrier lifting device, 1
DESCRIPTION OF SYMBOLS 1 ... Lift arm (lift member), 12 ... Cargo stand, 13
... Cart stoppers, 14L, 14R ... Left and right tilt cylinder devices, 14La, 14Ra ... Return springs,
15L, 15R ... Left and right lift cylinder devices, 16 ... D
C motor, 17 ... Hydraulic pump, 18 ... Tank, 19 ... Main oil passage, 19a ... Branch point, 20 ... Oil passage to right tilt cylinder device, 21 ... Oil passage to right lift cylinder device, 2
2 ... Oil passage for left (oil passage to left tilt cylinder device and left lift cylinder device), 22a ... Branch point, 23 ... Oil passage to left tilt cylinder device, 24 ... Oil to left lift cylinder device Road, 25 ... Right tilt valve, 25s ... Right tilt valve solenoid, 26 ... Right lift valve, 26s ... Right lift valve solenoid, 27 ... Left tilt valve, 27s ...
Left tilt valve solenoid, 28 ... Left lift valve, 28s
... Left lift valve solenoid, 29 ... Speed-up valve, 29s ...
Accelerating valve solenoid, 30 ... Lowering valve, 30s ... Lowering valve solenoid, 31 ... Check valve, 32 ... Discharge oil passage, 33 ...
First discharge valve, 34 ... Second discharge valve, 35 ... Relief oil passage, 36 ... Relief valve, 37 ... Pressure switch, 41 ... Open switch, 42 ... Down switch, 43 ... Tilt down switch, 44 ... Tilt up Switch, 45 ... Raising switch, 46 ... Closing switch, 47 ... Tank oil passage.

Claims (4)

[Claims] 1. A load receiving platform elevating device comprising a pair of lift cylinder devices for lifting and lowering a lift member that pivotally supports a load receiving base at one end, and a pair of tilt cylinder devices for rotating the load receiving base. In one embodiment, the oil passage to one tilt cylinder device of the pair of tilt cylinder devices is configured to be connected to the tank oil passage when the load receiver is opened and closed. . 2. A load receiving platform elevating device comprising a pair of lift cylinder devices for lifting and lowering a lift member pivotally supporting a load receiving base at one end, and a pair of tilt cylinder devices for rotating the load receiving base. In, the oil passage to one lift cylinder device of the pair of lift cylinder devices is connected to the tank oil passage by an operation of raising or lowering the load receiving base when no load is loaded on the load receiving base. A cradle lifting device characterized by being configured as described above. 3. The oil passage to one tilt cylinder device of the pair of tilt cylinder devices is configured to be connected to the tank oil passage when the load receiving tray is opened and closed. Item 2. A loading platform lifting device according to Item 2. 4. An oil passage to one cylinder device of the tilt cylinder device is connected to a tank oil passage during a tilt-up operation or a tilt-down operation when no load is loaded on the load receiving tray. The loading platform elevating device according to claim 3, wherein the loading platform elevating device.