JPH0811618A - Loading platform elevator - Google Patents

Abstract

PURPOSE:To harmonize the expansive operation of a pair of hydraulic cylinders by ensuring supply and discharge of pressure oil matching to the supply and discharge amount of pressure oil supplied to and discharged from the first cylinder to/from the second hydraulic cylinder. CONSTITUTION:A first hydraulic cylinder 13 is connected with a supply pipe 44 via which pressure oil is supplied from an oil pump 41 to operate the first hydraulic cylinder 13 to the direction of moving up a loading platform 30 an a second connection pipe 47 via which pressure oil is discharged from a head-side chamber 14b to operate the first hydraulic cylinder to the direction of moving down the platform, in a switchable manner. A fluid communication pipe 48 is provided between a pair of hydraulic cylinders, via which the respective rod-side chambers 14a, 24a are connected together so that pressure oil is supplied as required from the rod-side chamber 14a of the first hydraulic cylinder to the rod-side chamber 24a of the second hydraulic cylinder to operate the second hydraulic cylinder to the direction of moving up the loading platform 30 while pressure oil is returned as required from the rod-side chamber 24a of the second hydraulic cylinder to the rod-side chamber 14a of the first hydraulic cylinder to operate the second hydraulic cylinder to the direction of moving down the platform.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an elevating / lowering drive system of a load-carrying platform lifting device for lifting a load-carrying platform in a horizontal state on which loads and the like are placed.

[0002]

2. Description of the Related Art Conventionally, as a device for raising and lowering a receiving tray, for example, as disclosed in Japanese Utility Model Publication No. 4-31165,
A pair of left and right columns extending in the vertical direction, sliders slidably held in the vertical columns on the columns, and left and right ends respectively supported by the sliders in a substantially horizontal state, and a load receiver that moves up and down along the columns. A stand, a wire member whose one end is connected to each slider, and an elevating means such as a fluid cylinder for raising and lowering each wire member to elevate each slider are provided, and each wire by the elevating means is interposed. It is known that the load receiving platform is raised and lowered by raising and lowering a slider.

[0003]

However, in the above-described conventional load receiving platform elevating device, the driving force from the elevating means is transmitted to the slider through the wire member, so that the wire member is interposed between the elevating means and the slider. A plurality of rollers that slide in a stretched state are required, which makes the structure very complicated. Further, it is necessary to periodically replace the wire member in consideration of slack or breakage of the wire member, which makes maintenance work very troublesome.

Therefore, by using a pair of left and right fluid cylinders (elevating means), one end thereof, that is, a cylinder tube or a piston rod is fixed to the strut side, while the other end (piston rod or cylinder tube) is directly connected to the slider, Fluid is supplied from the fluid supply means to the pair of fluid cylinders through the distribution valve, and the fluid cylinders are expanded and contracted to form a load receiving platform elevating device in which wires are eliminated. It is possible to simplify the structure of the device and simplify the maintenance work. However, in this device, a difference in the load load from the load receiving platform to the pair of fluid cylinders, a difference in the flow resistance of the fluid to each fluid cylinder, and the like cause a difference in the amount of fluid supplied to each fluid cylinder. The expansion and contraction operations of the fluid cylinder may not be synchronized.

The present invention has been made in view of the above points, and an object of the present invention is to improve the one in which the pair of fluid cylinders are directly connected to the slider.
A pair of fluid cylinders is configured so that the fluid that matches the supply / discharge amount of fluid that is supplied to or discharged from one of the pair of fluid cylinders is reliably supplied to or discharged from the other fluid cylinder. It is to make sure that the expansion and contraction motions of are synchronized.

[0006]

In order to achieve the above-mentioned object, a means for solving the problems according to the invention as set forth in claim 1 is to provide a pair of left and right support columns extending in the vertical direction and a vertical support for each support column as a load receiving platform elevating device. A slider held slidably in the direction
Left and right ends are supported by the respective sliders in a substantially horizontal state, and a load receiving platform that moves up and down along with the slider along with the slider, and a pair of expandable and retractable first and second fluids arranged in parallel with the pair of supporting columns, respectively. Assuming that a cylinder is provided with a cylinder, each piston of the pair of fluid cylinders is connected to either one of a slider and a support via a piston rod, and a cylinder tube is connected to the other of the slider and the support. . One end of the first fluid cylinder of the pair of fluid cylinders is connected to the head side chamber and the other end thereof is connected to the fluid supply means, and the fluid is supplied from the fluid supply means to raise the load receiving tray. A feed pipe for activating the first cylinder in a direction, and one end thereof connected to the same head side chamber as one end of the feed pipe, and for activating the first fluid cylinder in a direction for discharging fluid from the head side chamber and lowering the load receiving tray. A discharge pipe and a switching valve that switches between a supply position that allows the fluid to be supplied to the head-side chamber via the supply pipe and a discharge position that allows the fluid to be discharged through the discharge pipe are provided. Further, between the pair of fluid cylinders, one end is connected to the rod side chamber of the first fluid cylinder and the other end is connected to the rod side chamber of the second fluid cylinder, and fluid to the head side chamber of the first fluid cylinder is provided. When supplying the fluid, the fluid is supplied from the rod side chamber of the first fluid cylinder to the rod side chamber of the second fluid cylinder to operate the second fluid cylinder in the direction of raising the load receiving platform, while the fluid is discharged from the head side chamber of the first fluid cylinder. Second
The second direction in which the fluid is returned from the rod-side chamber of the fluid cylinder to the rod-side chamber of the first fluid cylinder to lower the load carrier.
The communication pipe for operating the fluid cylinder is provided.

[0007] The solving means taken by the invention of claim 2 is,
According to the first aspect of the present invention, a pair of fluid cylinders are specified and arranged so that the rod-side chambers are located on the upper side and the head-side chambers are located on the lower side.

[0008]

According to the above-mentioned structure, according to the first aspect of the present invention,
When raising the loading tray, switch the switching valve to the supply position,
When fluid is supplied from the fluid supply means to the head-side chamber of the first fluid cylinder of the pair of left and right fluid cylinders through the supply pipe and the head-side chamber is expanded, the first fluid cylinder is moved in the direction of raising the load receiving platform. Works. And
With the expansion of the head-side chamber of the first fluid cylinder, the rod-side chamber of the first fluid cylinder to which the supply pipe is not connected shrinks, and the fluid of the rod-side chamber is discharged as the rod-side chamber shrinks. The discharged fluid is supplied to the same chamber of the second fluid cylinder as the first fluid cylinder via the communication pipe, and the second fluid cylinder operates in the direction of raising the load receiving base. Since the amount of fluid supplied to the chamber of the second fluid cylinder when the load receiving platform is raised is the same as the amount of fluid discharged from the rod-side chamber of the first fluid cylinder, the fluid supply means The fluid supplied only to the head-side chamber of the one-fluid cylinder causes the pair of fluid cylinders to always operate in synchronism with each other, so that the load receiving platform is kept horizontal and smoothly rises.

On the other hand, when lowering the load receiving table, the switching valve is switched to the discharge position, and the fluid is discharged from the head side chamber of the first fluid cylinder through the discharge pipe, so that the head side chamber of the first fluid cylinder shrinks. , The first fluid cylinder operates in the direction of lowering the load receiving table. Then, when the rod-side chamber expands as the head-side chamber of the first fluid cylinder contracts, fluid accompanying the expansion of the rod-side chamber is supplied to the rod-side chamber from the rod-side chamber of the second fluid cylinder via the communication pipe (return). ) Then, the second fluid cylinder operates in the direction in which the load receiving tray is lowered. The discharge amount of the fluid discharged from the rod side chamber of the second fluid cylinder when the load receiving platform descends, that is, the fluid supplied to the rod side chamber of the first fluid cylinder is the same as the fluid discharged from the head side chamber of the first fluid cylinder. The amount of fluid discharged from the head-side chamber of the first fluid cylinder and the amount of fluid discharged from the rod-side chamber of the second fluid cylinder are the same as the amount discharged in order to supplement the amount discharged. And the pair of fluid cylinders are always operated in synchronization with each other by the fluid discharged from only the head side chamber of the first hydraulic cylinder, so that the load receiving platform is kept horizontal and smoothly descends.

According to the second aspect of the invention, the pair of fluid cylinders are arranged so that the rod-side chambers are located on the upper side and the head-side chambers are located on the lower side. Dust and the like that settle are prevented from being caught in the seal material around the piston rod that seals the piston rod against the cylinder tube, and the durability of the seal material can be improved.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 and FIG. 5 show a luggage carrier using the load receiving platform raising / lowering device according to the first embodiment of the present invention. A chassis 2 is connected to a rear portion of the vehicle 1. A luggage box 3 is mounted on the chassis 2. The packing box 3 has a floor 3a.
And a front wall (not shown) that surrounds the floor 3a in the front-rear and left-right directions, a rear wall 3f, left and right side walls 3b and 3c, and a ceiling wall 3d having a shape substantially matching the floor 3a. .
The rear wall 3f has an opening 3e that opens to the rear of the floor 3a.
It is configured with a tailgate that can be opened and closed backward to close the.

At the rear end of the packing box 3, there is a loading tray 3 which will be described later.
A load receiving platform elevating device 4 for elevating 0 is provided. The load receiving platform elevating / lowering device 4 is provided with posts 10 and 20 as a pair of left and right columns extending vertically from the rear ends of the left and right side walls 3b and 3c, which are respectively provided upright on both left and right ends of the floor 3a. The upper ends of the left-side post 10 and the right-side post 20 are located at the left and right ends of the ceiling wall 3d, respectively. Each of the posts 10 and 20 is formed in a rectangular frame shape in cross section, and groove portions 10a and 20a that extend in the vertical direction and open at the lower ends are provided on the lower portions of the rear surfaces of the posts 10 and 20, respectively.

Here, the structure of each of the posts 10 and 20 is shown in FIG.
1 to 2, the first slider 11 of the left post 10 is slidably held in the vertical direction on the rear side of the left post 10, as will be described with reference to FIGS. Has been done. A roller 12 which is in sliding contact with the inner surface of the rear surface of the left post 10 is rotatably supported at the upper rear position of the first slider 11. On the other hand, a first hydraulic cylinder 13 (first fluid cylinder) that is vertically expandable and retractable is housed on the front side of the left post 10. The first hydraulic cylinder 13 includes a cylinder tube 14 and a piston 15 that slides in the cylinder tube 14.
And a piston rod 16 mounted on the upper surface of the piston 15 and protruding upward from the inside of the cylinder tube 14. The inside of the cylinder tube 14 is divided by a piston 15 into an upper rod side chamber 14a and a lower head side chamber 14b. A roller 17 is slidably supported at a lower position in the left post 10 so as to be in sliding contact with the front surface side of the first slider 11.
The lower end of the cylinder tube 14 of the first hydraulic cylinder 13 is on the lower end of the left post 10, and the tip (upper end) of the piston rod 16 is on the bracket 11a protruding forward from the upper end of the front part of the first slider 11. Installed.

On the other hand, as shown in FIGS. 1 and 3, a second slider 21 is slidably held in the vertical direction on the rear side of the right post 20. At the rear upper end position of the second slider 21, a roller 22 that slidably contacts the inside of the rear surface of the right post 20 is rotatably supported. on the other hand,
A second hydraulic cylinder 23 (the other fluid cylinder) that is vertically expandable and contractible is housed on the front side of the right post 20 so as to be vertically slidable. The second hydraulic cylinder 23 is
A cylinder tube 24 that is slidable in the vertical direction, a piston 25 that slides in the cylinder tube 24, and is attached to the upper surface of the piston 25.
4 and a piston rod 26 protruding upward from the inside. Inside the cylinder tube 24, an upper rod side chamber 24a and a lower head side chamber 2 are formed by a piston 25.
It is divided into 4b. A roller 27, which is in sliding contact with the front surface side of the second slider 21, is rotatably supported at a central position in the right post 20. A roller 29, which is in sliding contact with the front surface side of the second slider 21, is rotatably supported at the lower end position in the right post 20. In the second hydraulic cylinder 23, the lower end of the cylinder tube 24 of the second hydraulic cylinder 23 is attached to the bracket 21a protruding forward from the vertical center of the front part of the second slider 21.
Piston rods 26 are attached to the upper ends of the right posts 20, respectively. In this case, the first hydraulic cylinder 13 and the second hydraulic cylinder 23 are arranged so that expansion and contraction according to the amount of pressure oil supplied to and discharged from the chambers 14a, 14b, 24a, 24b of the respective cylinder tubes 14, 24 are synchronized. Are formed the same.

The lower ends of the sliders 11 and 21 project rearward through the groove portions 10a and 20a, respectively, and the lower ends rotate to the left and right end positions of the front end portion of the plate-shaped load receiving base 30. It is supported freely. The receiving platform 30 is
It can be erected between a use position where a load can be laid down horizontally when used and a storage position which stands up along the rear surfaces of the posts 10 and 20 when stored. Due to the expansion and contraction of the hydraulic cylinders 13 and 23,
It is configured to move up and down along with the sliders 11 and 21 along the posts 10 and 20 between a height position substantially matching the ground surface and a height position substantially matching the floor 3a of the packing box 3. .

Next, a hydraulic circuit for supplying and discharging hydraulic pressure to and from the hydraulic cylinders 13 and 23 will be described with reference to FIG.

In FIG. 1, reference numeral 41 is a hydraulic pump as a fluid supply means, and this hydraulic pump 41 is provided in the middle of a supply pipe 44 whose one end is immersed in an oil tank 42. Pressure is applied to the oil sucked up through the pipe 44. The other end of the supply pipe 44 is connected to the head-side chamber 14b of the first fluid cylinder 13, and supplies pressure oil from the oil pump 41 to the head-side chamber 14b to raise the load receiving platform 30 in the first direction.
The hydraulic cylinder 13 is operated, that is, extended. A check valve 44a is provided in the supply pipe 44. Further, the head side chamber 24b of the second hydraulic cylinder 23 and the oil tank 42 are connected to each other via a circulation pipe 45 so that oil can flow between the two chambers 24b and 42. Supply pipe 4 on the downstream side of the check valve 44a
4 and the flow pipe 45, a relief valve for circulating a part of the pressure oil to the oil tank 42 (flow pipe 45) when the hydraulic pressure of the pressure oil in the supply pipe 44 becomes higher than a predetermined pressure. The 1st connection pipe 46 which has 46a is connected. Further, between the supply pipe 44 and the flow pipe 45 on the downstream side of the check valve 44a, the head side chamber 14b of the first hydraulic cylinder 13 is provided in a part of the supply pipe 44, the second connecting pipe 47 and the flow pipe. A second connecting pipe 47 (a discharge pipe) communicating with the oil tank 42 via 45 is connected. The second connecting pipe 47
In the second position, the second connecting pipe 47 is communicated with the first position (the left position in the figure) that shuts off the second connecting pipe 47 when the load receiving base 30 is raised and the second connecting pipe 47 is connected through the orifice when the load receiving base 30 is lowered.
An elevating valve 47a as a switching valve for switching to a position (right position in the drawing) is provided, and the second connecting pipe 47 is provided.
Is a direction in which the head cradle 30 is lowered by connecting the head side chamber 14b of the first hydraulic cylinder 13 to the oil tank 42 and discharging the pressure oil from the head side chamber 14b when the lifting valve 47a is switched to the second position. In addition, the first fluid cylinder 13 is operated or contracted. Then, the first hydraulic cylinder 13 and the second hydraulic cylinder 23 described above.
Between one end and the rod side chamber 14a to which the supply pipe 44 is not connected and the other end is the rod side chamber 24a of the second hydraulic cylinder 23 (the same as the rod side chamber 14a of the first hydraulic cylinder 13). A communication pipe 48 connected to the chamber is provided. The communication pipe 48 is provided from the rod-side chamber 14a of the first fluid cylinder 13 to the second fluid cylinder 2 when pressure oil is supplied to the head-side chamber 14b of the first fluid cylinder 13 with the lifting valve 47a switched to the first position.
The first fluid cylinder in a state in which the lifting valve 47a is switched to the second position while the second fluid cylinder 23 is operated or contracted in the direction in which the pressure receiving oil is supplied to the rod side chamber 24a of No. 3 to raise the load receiving table 30. When the fluid is discharged from the head side chamber 14b of the rod 13, the rod side chamber 2 of the second hydraulic cylinder 23
The second hydraulic cylinder 23 is operated, that is, extended in a direction in which the pressure oil is returned from 4a to the rod side chamber 14a of the first fluid cylinder 13 to lower the load receiving table 30. Further, between the supply pipe 44 and the communication pipe 48 on the downstream side of the check valve 44a, the left and right hydraulic pressures are set to the first position (the left position in the figure) that normally shuts off the third connecting pipe 49. Cylinder 1
The third connecting pipe 49 when there is a difference in the extension of
A third connecting pipe 49 having a tuning valve 49a that is switched to a second position (right position in the drawing) for connecting the hydraulic pressure pump 41 and the hydraulic pipe 41 to replenish the communicating pipe 48 is connected.

Therefore, in the first embodiment described above, when the load receiving base 30 is raised, the hydraulic pump 41 sucks the oil from the oil tank 42 with the lifting valve 47a switched to the first position to shut off the second connecting pipe 47. The raised pressure oil is supplied to the head side chamber 14b of the first hydraulic cylinder 13 via the supply pipe 44.
When the head side chamber 14b is expanded by supplying the first fluid cylinder 13b to the first fluid cylinder 13, the first fluid cylinder 13 extends so as to raise the load receiving base 30. Then, the head side chamber 1 of the first hydraulic cylinder 13
With the expansion of 4b, the rod-side chamber 14a of the first hydraulic cylinder 13 to which the supply pipe 44 is not connected shrinks,
As the rod-side chamber 14a shrinks, the rod-side chamber 14a
The pressure oil of a is discharged, and the discharged pressure oil is
Of the second fluid cylinder 23 via the first fluid cylinder 1
3 is supplied to the same rod side chamber 24a as that of No. 3, and the second fluid cylinder 23 is shortened so as to raise the load receiving table 30. The amount of pressure oil supplied to the rod side chamber 24a of the second fluid cylinder 23 when the load receiving platform 30 is raised is the same as the amount of pressure oil discharged from the rod side chamber 14a of the first fluid cylinder 13. Therefore, the left and right hydraulic cylinders 13,
23 can be synchronized at all times, and the loading platform 3
It is possible to smoothly raise 0 while keeping 0 in a horizontal state.

On the other hand, when lowering the load receiving table 30, the elevating valve 47a is switched to the second position to communicate the second connecting pipe 47, and the head side chamber 14b of the first hydraulic cylinder 13 is opened to the oil tank 42. , Hydraulic pump 4
The pressure oil sucked up from the oil tank 42 by means of 1 and the pressure oil in the head-side chamber 14b of the first hydraulic cylinder 13 which circulates via the supply pipe 44 are transferred from the downstream end of the second connecting pipe 47 through the flow pipe 45 to the oil. It can be circulated (supplied) to the tank 42 and the head side chamber 24b of the second hydraulic cylinder 23.
The pressure oil is discharged from the head side chamber 14b of the first hydraulic cylinder 13 and the head side chamber 24 of the second hydraulic cylinder 23.
By supplying the pressure oil to b, the head side chamber 14b of the first hydraulic cylinder 13 is contracted, and the first hydraulic cylinder 13 is contracted so as to lower the load receiving table 30. As the head side chamber 14b of the first hydraulic cylinder 13 is contracted, the rod side chamber 1
When 4a expands, as the rod-side chamber 14a expands, pressure oil is supplied (returned) to the rod-side chamber 14a from the rod-side chamber 24a of the second hydraulic cylinder 23 via the communication pipe 48.
Then, the second fluid cylinder 23 extends so as to lower the load receiving table 30. The amount of pressure oil discharged from the rod-side chamber 24a of the second fluid cylinder 23 when the load receiving table 30 is lowered is equal to that of the rod-side chamber 14a of the first hydraulic cylinder 13a.
Since it is the same amount as the pressure oil supplied to the pair of hydraulic cylinders, the pair of left and right hydraulic cylinders 13 and 23 can be always synchronized, and the load carrier 30 can be smoothly lowered while being kept horizontal.

Further, since the load receiving platform raising / lowering device 4 does not require a wire member and a plurality of rollers, the structure of the load receiving platform raising / lowering device 4 can be simplified and the wire member can be used. It is also possible to simplify the maintenance work by eliminating the need for regular wire member replacement work in consideration of slack and breakage. In addition, when the first and second hydraulic cylinders 13 and 23 are extended and the load receiving base 30 tilts to the left and right and is out of synchronization, the tuning valve 49a is set to the second position.
By switching to the position and supplying the pressure oil into the communication pipe 48 through the third connecting pipe 49, the shortage of the pressure oil is compensated for and the tuning is performed. Therefore, troublesome tuning work can be performed only by the tuning valve 49a, and maintenance is performed. The work can be effectively simplified.

The first hydraulic cylinder 13 and the second hydraulic cylinder 23 are respectively provided in the rod side chambers 14a and 24a.
Is arranged on the upper side, and the head side chambers 14b, 24b are arranged on the lower side.
It is possible to prevent dust and the like settled in the pressure oil in a from being caught in the sealing material around the piston rods that seal the piston rods 16 and 26 to the cylinder tubes 14 and 24. It is also possible to improve the sex.

Next, a second embodiment of the present invention will be described with reference to FIG.

This second embodiment is the second embodiment of the first embodiment.
The arrangement of the hydraulic cylinders has been changed.

That is, in this embodiment, as shown in FIG. 6, the second hydraulic cylinder 51 includes a cylinder tube 52.
A piston 53 that slides in the cylinder tube 52, and a piston rod 54 that is attached to the lower surface of the piston 53 and projects downward from the inside of the cylinder tube 52.
It has and. The inside of the cylinder tube 52 is partitioned by a piston 53 into a lower rod side chamber 52a and an upper head side chamber 52b. In the second hydraulic cylinder 51, the upper end of the cylinder tube 52 is at the upper end of the right post 20, and the tip (lower end) of the piston rod 54.
Are attached to brackets 21a that project forward from the vertical center of the front part of the second slider 21.

The head side chamber 52b of the second hydraulic cylinder 51 and the oil tank 42 are connected via a flow pipe 45. The rod-side chamber 14a of the first hydraulic cylinder 13 and the rod-side chamber 52a of the second hydraulic cylinder 51 are connected to each other via a communication pipe 48.

Therefore, in the second embodiment described above, when the load receiving table 30 is raised, the hydraulic oil is supplied from the hydraulic pump 41 with the elevating valve 47a switched to the first position to shut off the second connecting pipe 47. When the head side chamber 14b is expanded by supplying it to the head side chamber 14b of the first hydraulic cylinder 13 through the pipe 44, the first fluid cylinder 13 extends so as to raise the load receiving table 30. The rod-side chamber 14a of the first fluid cylinder 13 contracts as the head-side chamber 14b of the first hydraulic cylinder 13 expands, and the pressure oil discharged from the rod-side chamber 14a as the rod-side chamber 14a contracts is a communication pipe. Second fluid cylinder 5 through 48
It is supplied to the same rod-side chamber 52a as the first fluid cylinder 13 and the second fluid cylinder 23 contracts so as to raise the load receiving table 30. When the loading platform 30 is raised, the second
The amount of pressure oil supplied to the rod-side chamber 52a of the fluid cylinder 51 is the same as that of the rod-side chamber 14a of the first fluid cylinder 13.
Since it is the same as the amount of pressure oil discharged from the first hydraulic cylinder 13, the amount of pressure oil supplied to the head side chamber 14b of the first hydraulic cylinder 13 and the pressure supplied to the head side chamber 52b of the second hydraulic cylinder 51. The amount of oil corresponds to each other and the hydraulic pump 41
By the pressure oil supplied only to the head side chamber 14b of the first hydraulic cylinder 13, the pair of left and right hydraulic cylinders 13,
51 can be synchronized at all times, and the loading tray 3
It is possible to smoothly raise 0 while keeping 0 in a horizontal state.

On the other hand, when lowering the load receiving base 30, by switching the elevating valve 47a to the second position and communicating the second connecting pipe 47, the pressure oil from the hydraulic pump 41 is
Along with the pressure oil in the head side chamber 14b of the first hydraulic cylinder 13 that recirculates via the supply pipe 44, from the downstream end of the second connecting pipe 47 to the oil tank 42 and the head side chamber 52b of the second hydraulic cylinder 51 via the flow pipe 45. It can be distributed. Discharge of pressure oil from the head side chamber 14b of the first hydraulic cylinder 13 and the head side chamber 52b of the second hydraulic cylinder 51.
By supplying the pressure oil to the head side chamber 14b of the first hydraulic cylinder 13, the first hydraulic cylinder 13 contracts so as to lower the load receiving table 30. As the head side chamber 14b of the first hydraulic cylinder 13 is reduced, the rod side chamber 14 is reduced.
When a increases, pressure oil is supplied (returned) from the rod-side chamber 52a of the second hydraulic cylinder 51 to the rod-side chamber 14a through the communication pipe 48 as the rod-side chamber 14a expands, and the load receiving tray 30 descends. The second fluid cylinder 51 extends so as to allow it. The amount of pressure oil discharged from the rod-side chamber 52a of the second fluid cylinder 51 and the pressure oil supplied to the rod-side chamber 14a of the first hydraulic cylinder 13a at the time of lowering of the load receiving table 30 should be the same. Therefore, the amount of the pressure oil discharged from the head side chamber 14b of the first hydraulic cylinder 13a and the amount of the pressure oil discharged from the rod side chamber 52a of the second hydraulic cylinder 51 match each other, and The pair of left and right hydraulic cylinders 13 and 51 can be constantly synchronized by the pressure oil discharged from only the head side chamber 14b, and the load receiving table 30 can be smoothly lowered while being kept horizontal.

In each of the above-described embodiments, the case where the load receiving platform raising / lowering device is used for the luggage carrier 1 has been described, but the load receiving platform raising / lowering device may be used for a warehouse or the like partitioned into a plurality of floors. .

[0030]

As described above, according to the loading platform elevating / lowering device of the first aspect of the invention, the first of the pair of fluid cylinders is provided.
Since fluid is supplied and discharged between the rod-side chamber of the fluid cylinder and the rod-side chamber of the second fluid cylinder via the communication pipe,
The amount of fluid supplied to and discharged from the head-side chamber of the first fluid cylinder and the amount of fluid supplied to and discharged from the rod-side chamber of the second fluid cylinder are made to coincide with each other, and the operations of the pair of fluid cylinders are always synchronized to make the load receiving platform horizontal. It can be raised and lowered smoothly while keeping it. In addition, the need for a wire member eliminates the need for a plurality of rollers and the like, which simplifies the structure of the load-carrying platform lifting device and also periodically replaces the wire member in consideration of slack and breakage of the wire member. It is also possible to simplify the maintenance work by eliminating the work.

According to the load receiving platform raising / lowering device of the second aspect of the present invention, since the rod-side chambers of the pair of fluid cylinders are located on the upper side, the surroundings of the piston rod such as dust settled in the rod-side chambers. It is possible to prevent the sealing material from being bitten into the sealing material and improve the durability of the sealing material.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram according to a first embodiment of the present invention.

FIG. 2 is also a vertical side view of the left post.

FIG. 3 is likewise a vertical side view of the right post.

FIG. 4 is also a rear view of the vehicle.

FIG. 5 is a rear side view of the vehicle.

FIG. 6 is a view corresponding to FIG. 1 according to the second embodiment.

[Explanation of symbols]

 10, 20 Posts (posts) 11, 21 Slider 13 First hydraulic cylinder (first fluid cylinder) 15, 25, 53 Piston 16, 26, 54 Piston rod 14, 24, 52 Cylinder tube 14a Rod side chamber of the first hydraulic cylinder 14b Head side chamber of the first hydraulic cylinder 23,51 Second hydraulic cylinder (second fluid cylinder) 24a, 52a Rod side chamber of the second hydraulic cylinder 30 Load carrier 44 Supply pipe 47 Second connecting pipe (discharging pipe) 47a Lift valve ( Switching valve) 48 communication pipe

Claims (2)

[Claims] 1. A pair of left and right support columns extending in the vertical direction, sliders slidably held in the respective support columns in the vertical direction, and left and right ends respectively supported by the respective sliders in a substantially horizontal state. The cargo cradle that moves up and down along the pillars is provided with a pair of expandable and contractable first and second fluid cylinders that are respectively arranged in parallel with the pair of pillars. In the pair of fluid cylinders, each piston has a piston rod. Is connected to either one of the slider and the support via the cylinder tube is connected to the other of the support and the slider. One end of the first fluid cylinder of the pair of fluid cylinders is The first cylinder is connected to the head-side chamber and the other end is connected to a fluid supply means, and supplies fluid from the fluid supply means to raise the load receiving tray. A supply pipe for operating the da one end connected to the same head-side chamber and one end of the supply pipe, a discharge pipe for operating the first fluid cylinder in a direction to lower the receiving platform by discharging the fluid from the head side chamber,
A switching valve that switches between a supply position that allows the fluid to be supplied to the head-side chamber through a supply pipe and a discharge position that allows the fluid to be discharged through the discharge pipe is provided, and the pair of Between the fluid cylinders, one end is connected to the rod side chamber of the first fluid cylinder and the other end is connected to the second fluid chamber.
It is connected to the rod side chamber of the fluid cylinder, and when the fluid is supplied to the head side chamber of the first fluid cylinder, the fluid is supplied from the rod side chamber of the first fluid cylinder to the rod side chamber of the second fluid cylinder to raise the load receiving platform. While operating the two-fluid cylinder, when the fluid is discharged from the head-side chamber of the first fluid cylinder, the fluid is returned from the rod-side chamber of the second fluid cylinder to the rod-side chamber of the first fluid cylinder, and the second fluid is moved in the direction of lowering the loading platform. A cargo platform raising / lowering device, characterized in that a communication pipe for operating a cylinder is provided. 2. The load platform raising / lowering device according to claim 1, wherein the pair of fluid cylinders are arranged such that the rod-side chambers are located on the upper side and the head-side chambers are located on the lower side.