DE29710755U1 - Hydraulically height-adjustable lifting device for motor vehicles - Google Patents

Description

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Zapf GmbH + Co. ··· ··* *··**··*

Hydraulically height-adjustable lifting device for motor vehicles

Description

The present invention relates to a hydraulically height-adjustable lifting device for motor vehicles, according to the preamble of claim 1.

Hydraulically height-adjustable lifting devices for motor vehicles are widely known in the state of the art. For example, they are used in parking facilities for parking vehicles one above the other.

Lifting devices of this type have two functions to fulfill:

at least one platform must be able to be raised and lowered parallel to the starting position, regardless of the position and size of the load

In the rest position, at least one platform must also be kept parallel to the starting position and in a fixed position, regardless of the position and magnitude of the load.

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From DE 24 04 833 C3 a device for parking vehicles on platforms arranged one above the other is known, whereby the synchronization takes place via elaborately designed cable pulleys and steel cables.

A similar device for parking vehicles is known from DE 25 60 463 C2, which also has a synchronization device. The synchronization is achieved by means of sprockets driven by a chain.

Both of the above solutions are obviously very complex and correspondingly expensive.

To simplify the mechanical effort of the above-mentioned solutions, a hydraulic drive for a parking device with plate shapes arranged one above the other is proposed according to DE 196 19 588 Cl, whereby at least two lifting cylinders each having a first and second chamber are provided, which are connected to the platform on the one hand and firmly connected to a support structure on the other. Each lifting cylinder has a forward flow control valve with a hydraulic control circuit in its forward line and a return flow control valve with a hydraulic control circuit in its return line.

The hydraulically height-adjustable lifting device for motor vehicles of this state of the art, however, has the disadvantage of a particularly complex hydraulic control device. The flow control valves, one in the supply line and one in the return line of the corresponding

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the chamber of the lifting cylinder also require a hydraulic control circuit with appropriate comparators, regulating and control elements. Such flow control valves also have relatively large tolerances in their function, so that the function of parallel raising and lowering is only partially guaranteed.

In addition, such flow control valves cannot guarantee positional stability in the rest position. If there are pressure differences between the two lifting cylinders due to uneven loading of the platform, either a mechanical synchronization device of the type mentioned above must be provided to ensure positional stability, or each cylinder must be shut off separately with a valve that closes leak-free or essentially leak-free, which further increases the control effort. This becomes more important the more lifting cylinders are provided.

The present invention is therefore based on the task of improving a hydraulically height-adjustable lifting device for motor vehicles in such a way that a lifting device with excellent synchronization properties of the lifting cylinders is created using structurally simple mechanical and hydraulic means. In addition, it should be possible to ensure in the rest position with little control effort that the at least one platform is held in a fixed position parallel to the starting position, regardless of the position and size of the load.

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This object is solved by the features of claim 1.

Because a device is provided for each lifting cylinder to store the volume change of the hydraulic fluid in at least one of the two chambers of each lifting cylinder, and because these devices are coupled to one another in such a way that the storage quantity in all devices is identical or essentially identical, a particularly simple lifting device is created which ensures excellent synchronization properties of the lifting cylinders. By coupling the storage devices, it is achieved that when the volume in one storage device changes, the same volume change occurs in the other storage device(s), whereby an identical or essentially identical change is also generated in the lifting cylinders.

Advantageously, the design according to the invention also creates a particularly robust system which also has few moving parts and a particularly simple structure of the hydraulic system.

The particularly simple construction is also achieved in that the storage devices each have a first and a second chamber, wherein hydraulic fluid is present in the first chamber, both chambers are variable in their volume, and at least all of the first chambers have identical volumes.

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In order to control a corresponding storage volume, a movable piston is provided between the two chambers of each storage device, which separates the first from the second chamber in a leak-free or essentially leak-free manner.

A particularly simple and effective control of the volume change of the storage devices is achieved by connecting the pistons of the storage devices to one another and the movement of one piston causing the same movement of the other piston. This creates a forced volume change in all the corresponding chambers of the storage devices and thus also in the associated chambers of the lifting cylinders.

As a particularly simple connection, according to the invention, at least one piston rod is advantageously provided for each piston, to which the adjacent piston or pistons are connected.

Advantageously, at least one of the interconnected pistons has a further piston rod which extends outside the chamber. A suitable drive can engage this and move the piston rod in the desired direction by a desired amount.

In a preferred embodiment, each piston of a storage device has two piston rods, each extending in an opposite direction from the piston.

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According to a preferred embodiment of the invention, the second chambers of each storage device advantageously also contain hydraulic fluid or are filled with it and are connected to a line for supplying or discharging hydraulic fluid, so that the volume change of the storage quantity in one of the second chambers causes an identical or essentially identical change in the storage quantity in the respective associated first chamber.

In a first embodiment of the lifting device according to the invention, two lifting cylinders are provided.

In a second, preferred embodiment, the lifting device has three lifting cylinders. These are arranged at the three corners of an imaginary triangle. In a preferred embodiment, two of the lifting cylinders are connected to the platform on the long sides and the third lifting cylinder is located on one end face.

Alternatively, in a particularly preferred embodiment of the invention, four lifting cylinders can be provided, which are arranged essentially on the long sides in the area of the corners of the plates. This arrangement of the lifting cylinders enables a statically particularly favorable design of the platform with small cross-sections, construction heights and low weight.

Preferably, each first chamber of each lifting cylinder is filled with hydraulic fluid and separated from the second chamber by a movable piston.

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Preferably, the piston of each lifting cylinder is sealed against the side wall of the lifting cylinder so that it is leak-free. This leads to the desired synchronization of the lifting cylinders.

In a particularly simple design, it is sufficient to fill the first or lower chamber of each lifting cylinder with hydraulic fluid and to make the volume of the hydraulic fluid variable, whereby the piston is moved accordingly and the associated platform is moved with it. In this case, the weight of the platform and, if applicable, the vehicle on the platform must be moved with it. When the hydraulic fluid is drained, the piston and thus the platform moves back down under its own weight.

For faster operation, a counterpressure device is preferably provided in the second or upper chamber of the lifting cylinder, which acts on the piston. As a result, when the hydraulic fluid is released from the first or lower chamber, it is accelerated by the counterpressure.

In a simple embodiment, the counterpressure device can be provided in the form of a spring system, for example a coil spring.

Alternatively and preferably, the counterpressure device is also formed by a hydraulic fluid.

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Thus, according to the preferred embodiment described above, the piston rod extends downwardly through and beyond the lower chamber and is connected to at least one of the platforms.

Alternatively, the lifting cylinder can also be installed "upside down", with the piston rod then extending upwards.

In the latter installation variant, either the lower chamber can be connected to the storage device or the lower and upper chambers are connected to each other with a return line, so that when lifting only the difference between the amount of fluid conveyed into the lower chamber and the amount of fluid displaced from the upper chamber needs to be removed from the storage device or stored again when lowering.

The lifting device according to the invention enables the position of the platform(s) in the rest position to be secured parallel to the starting position with particularly low control effort if a leak-free or essentially leak-free closing valve is provided in the common supply line to the second chambers of the storage device. The leak-free or essentially leak-free design and the coupling of the storage device ensure that the position is secured parallel to the starting position; with a single valve, the height of the platform(s) can also be secured.

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Overall, a lifting device is advantageously created in which the storage quantity is the same in all storage devices and thus any change in the storage quantity is converted into an equal change in the piston displacement of the pistons of the lifting cylinders.

Further details, features and advantages of the invention emerge from the following description with reference to the drawings. In which:

Figure 1 shows a hydraulically height-adjustable lifting device according to the invention in use in a garage with two platforms arranged one above the other in a side view;

Figure 2 shows the view according to arrow II of Figure 1;

Figure 3 shows the basic schematic structure of the

lifting device according to the invention according to a preferred embodiment with four lifting cylinders;

Figure 4 is a partial sectional view, similar to the view in Figure 2, of the basic installation method of a lifting cylinder in the opposite direction to Figure 3.

Firstly, it should be noted that the same or identical elements in the figures are designated by the same reference numerals.

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Figure 1 shows a schematic view of a cell-shaped parking facility 1 for motor vehicles, which has a box-shaped housing 3 that forms a garage. To save space, this garage has 2 platforms, an upper platform 5 and a lower platform 6, on each of which a vehicle 7 is arranged or parked.

As can be seen from Figure 1, the lower platform 6 is located at the bottom of the housing 3 and the upper platform 5 is at the height of the entry and exit edge 9 of the housing 3. A lifting device 11 is provided in the housing 3.

In the example shown in Figure 1 and Figure 2, the lifting device 4 has lifting cylinders 13 which are arranged near the side walls 15 and 16 of the housing 3 (Figure 2) and, as can be seen from Figure 1, extend essentially vertically.

The lifting cylinders 13 are hingedly connected to the housing at the top, in anchoring points 17, as can be seen in particular from Figure 2.

Referring to Figure 3, the hydraulic height-adjustable lifting device for motor vehicles according to the invention will now be described in more detail.

The lifting cylinders 13 have a first or lower chamber 19 and a second or upper chamber 21. Both chambers 19 and 21 are separated from one another by means of a piston 23. This separation is preferably leak-free, i.e. the piston is positioned in such a way relative to the piston wall of the cylinder

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sealed so that no hydraulic fluid can flow past the seal.

A piston rod 25 engages the piston 23. The piston rod 25 extends through the first or lower chamber 19 and beyond the lifting cylinder 19 and is connected to the upper platform 5.

Platform 5 is in turn connected to the lower platform 6.

The first or lower chamber 19 of each lifting cylinder is filled with hydraulic fluid, whereby this hydraulic fluid can be fed into or drained from the first or lower chamber 19 via a supply or drain line 27. Depending on the fluid supplied to the first chamber, the piston is raised or lowered or fixed in its stroke position.

The lifting device according to the invention further comprises a storage device 29, 30, 31, 32 for each lifting cylinder 13 for storing the volume change of the hydraulic fluid in the lower chamber 19 of each lifting cylinder

In the embodiment shown in Figure 3, each storage device 29, 30, 31, 32 is of the same design and has a cylindrical body in which a piston 33 is arranged. The piston divides the storage device 29, 30, 31, 32 into a first chamber 35 and a second chamber 37. The first chamber 35 is connected to the supply and discharge ports.

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Drain line of hydraulic fluid 27 and is separated from the second chamber 37 in a leak-free manner by means of the piston 33.

A piston rod 39 extends from both sides of the piston 33, the piston rods 39 being connected to one another.

In the preferred embodiment, the second chamber 37 of each storage device 29, 30, 31, 32 has a supply and discharge line for hydraulic fluid 41, which are branched off from a common line 43.

Furthermore, the second or upper chambers 21 of the lifting cylinders 13 also have supply and discharge lines 45, which are combined into a common line 47.

Both lines are connected to a pump 51 via a control valve 50 and a hydraulically releasable check valve 4 9. This pump system is of conventional design and is therefore not described further.

The functioning of the lifting device 11 according to the invention is described below.

As can be seen from Figure 3, the raising or lowering of the upper platform 5 and the associated lower platform 6 is carried out by actuating the lifting cylinder 13. In Figure 3, the piston 23 in the respective lifting cylinder is located essentially in the middle of the lifting cylinder and the pistons 33 of the storage devices 29, 30, 31, 32 are located

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also in the middle, so that essentially two equally sized first and second chambers 35 and 37 result.

If the upper platform 5 is now to be raised, hydraulic fluid is supplied via line 43 to the second chambers 37 of the storage devices 29, 30, 31, 32. This causes the pistons 33 to be displaced in the direction of the first chambers 35 of the storage devices 29, 30, 31, 32, i.e. to the left in Figure 3.

If a possible different volume change could occur in one of the second chambers 37 due to possible effects, such as a pressure difference in the lines 41, different distances of the hydraulic fluid, etc., the mechanical coupling of the pistons 33 to one another always produces an identical movement of the pistons 33 in one direction or the other. This means that in the closed system between the first chambers 35 of the storage devices 29, 30, 31, 32 via the inlet and outlet lines 27 and the first chambers 19 of the lifting cylinders 13, an identical volume exchange or an identical storage of the volume change occurs, whereby a corresponding synchronization is achieved in the four lifting cylinders and thus an exactly horizontal movement of the two plate shapes 5 and 6 is made possible.

For the sake of completeness, it should be noted that the connection between the upper platform 5 and the lower platform 6 is designed in such a way that a predetermined height clearance

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between both platforms, so that when the upper platform 5 is raised, this play is used to create a correspondingly increased distance between the upper platform 5 and the lower platform 6, whereby when the platform 5 is raised, there is a corresponding distance between the upper platform 5 and the roof of the vehicle 7, so that the driver of the vehicle 7 can comfortably get to his vehicle with sufficient headroom.

For the rapid lowering of the platforms 5 and 6, the control device 49 has a valve 50 that can be switched so that the hydraulic pressure generated by the pump 51 can be fed into the line with a corresponding change in volume and is thus fed to the upper chambers 21 of the lifting cylinders 13 via the lines 45. At the same time, a corresponding amount of hydraulic fluid is drained from the second chambers 37 of the storage devices 29, 30, 31, 32 via the line 43.

When the lifting device is in the rest position, pressure differences in the individual lifting cylinders 13 due to uneven loads cannot cause the platforms 5, 6 to become inclined even over longer periods of time due to the leak-free sealing of the pistons 3 3 of the storage devices 29, 30, 31, 32. The hydraulically releasable check valve 49, which closes leak-free and is arranged in the common supply line 4 3 to the second chambers 3 7 of the storage devices 29, 30, 31, 32, also fixes the height of the platforms 5, 6 over long periods of time.

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Figure 4 shows an alternative embodiment. In the detail view, a lifting cylinder 13 is installed in the opposite installation direction to the installation direction according to Figure 3, so that its piston rod 25 does not extend downwards, but upwards. This means that the lower first chamber 19 is not penetrated by the piston rod 25, and by feeding hydraulic fluid via the line 27, the piston 23 with its piston rod 25 is pushed upwards, thus lifting the platforms 5 and 6 upwards.

From the supply and discharge lines 45 of the upper chamber 21 of the lifting cylinder 13 (these chambers are defined according to their installation position into upper and lower chambers), a return line 53 is provided, which connects the line 45 with the line 27. Consequently, the control devices 29, 30, 31, 32 only have to add a difference quantity to the lower chamber 19 that corresponds to the volume of the piston rod to be displaced, since the amount of fluid displaced from the upper chamber 21 is fed back into the lower chamber 19. It is also clear from Figure 4 that the piston 23 of the lifting cylinder 13 is connected to a corresponding position of the piston 33 of the storage devices 29, 30, 31, 32.

The present invention is not limited to the embodiments shown.

For example, a mechanical feed device can be provided on at least one of the piston rods 39 projecting towards the outside of the storage devices 29, 30, 31, 32.

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which displaces all pistons 33 of the storage devices 29, 30, 31, 32 equally due to the mechanical couplings by the piston rod 39 and thus produces equal volume changes in the first chambers 35 of the storage devices 29, 30, 31, 32. This means that a corresponding hydraulic supply to the second chambers 37 of the storage devices 29, 30, 31, 32 can be avoided.

The drive device acting on the piston rods 3 9 can either be a corresponding motor or a corresponding gear driven by a motor, or an additional hydraulic cylinder (not shown) which is actuated directly via the line 43.

This creates a hydraulically height-adjustable lifting device for motor vehicles, which is particularly advantageous for use in multi-storey platforms, parking garages or car parks. The embodiment shown shows two platforms, but any number of platforms can be arranged one above the other. Furthermore, the lateral dimension of the platforms in the example shown in Figures 1 and 2 only shows the possibility of accommodating one vehicle at a time. Alternatively, several vehicles can be accommodated per platform, so that such lifting devices are suitable, for example, for compact storage in car ferries or in car transport facilities, in particular ships for transporting motor vehicles.

It is also possible to arrange the lifting cylinders 13 between each platform so that the displacement of the

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Platforms can be positioned individually against each other. For example, platforms with trucks, cars, mobile homes, etc. can be spaced at different distances to enable optimal use of the storage space.

Claims (20)

G 0874-20 &idigr;"·#&idiagr;&iacgr;8 * &iacgr; ·**! * ***&iacgr; * ZapfGmbH + Co. "* ** *· "· " * Claims 1. Hydraulically height-adjustable lifting device (11) for motor vehicles (7), with at least one height-adjustable platform (5, 6) for receiving at least one vehicle (7), with at least two lifting cylinders (13) each having a first and a second chamber (19, 21), which are connected on the one hand to the platform (5) and on the other hand are fixedly connected to a carrying or support structure (3, 16) (at 17), wherein each lifting cylinder (13) is connected to at least one hydraulic line (27) for supplying or discharging hydraulic fluid, characterized, that for each lifting cylinder (13) a device (29, 30, 31, 32) is provided for storing the volume change of the hydraulic fluid in at least one of the two chambers (19) of each lifting cylinder (13), and that these devices (29, 30, 31, 32) are coupled together (39) in such a way that the storage quantity in G 0874-20 | *·*2_5 J * ·**; · "··&diams; Zapf GmbH + Co. all devices (29, 30, 31, 32) are identical or substantially identical. 2. Lifting device according to claim 1, characterized in that the storage devices (29, 30, 31, 32) each have a first (35) and a second (37) chamber, wherein hydraulic fluid is present in the first chamber (35), and both chambers (35, 37) are variable in their volume, and at least all of the first chambers have identical volumes. 3. Lifting device according to claim 2, characterized in that between the two chambers (35, 37) of each storage device (29, 30, 31, 32) a movable piston (33) is provided, which separates the first chamber (35) from the second chamber (37) in a leak-free or substantially leak-free manner. 4. Lifting device according to claim 3, characterized in that the pistons (33) of the storage devices (29, 30, 31, 32) are connected to one another and the movement of one piston (33) causes the same movement of the other piston(s) (33). 5. Lifting device according to claim 4, characterized in that each piston (33) is connected via a piston rod (39) to the adjacent piston(s) (33). 6. Lifting device according to claim 5, characterized in that at least one of the interconnected &bull; »· ff &diams;· ·· ***t 3731G0874-20 : "so; :: ; Zapf GmbH + Co. "' " Piston (33) has a further piston rod (39) which can be moved via a suitable drive. 7. Lifting device according to claim 5 or 6, characterized in that each piston (33) has two piston rods (39) which extend from the piston (33) into both chambers (35, 37). 8. Lifting device according to one of claims 2 to 7, characterized in that the second chambers (37) of each storage device (29, 30, 31, 32) are also filled with hydraulic fluid and are connected to a line (41, 43) for supplying or discharging hydraulic fluid, so that the volume change in one of the second chambers (37) of the storage devices (29, 30, 31, 32) causes an identical change in the storage quantity in all the first chambers (35) of the storage devices (29, 30, 31, 32). 9. Lifting device according to one of claims 1 to 8, characterized in that it has three lifting cylinders (13). 10. Lifting device according to claim 9, characterized in that two of the lifting cylinders (13) are connected to the long sides of the platform (5, 6) and the third lifting device is connected to the front side (55) of the platform (5) is connected. G 0874-20 *, ··?! J ;· ·· ··; ; Zapf GmbH + Co. "* ** ·· ·· ·· · 11. Lifting device according to one of claims 1 to 8, characterized in that four lifting cylinders (13) are provided. 12. Lifting device according to one of claims 1 to 10, characterized in that each first chamber (19) of the lifting cylinder (13) is filled with hydraulic fluid and is closed off from a second chamber (21) by a movable piston (23). 13. Lifting device according to claim 12, characterized in that the piston (23) leak-freely closes the first chamber (19) seals against the second chamber (21). 14. Lifting device according to one of claims 12 or 13, characterized in that the second chamber is provided with a counter-pressure device. 15. Lifting device according to claim 14, characterized in that the counter-pressure device is a spring system. 16. Lifting device according to claim 14, characterized in that the counterpressure device is hydraulic fluid. 17. Lifting device according to one of claims 1 to 16 characterized in that it has a piston rod (25) connected to the piston (23), which extends through the lower chamber (19) and beyond and is connected to at least one of the platforms (5, 6). G 0874-20 * "%2 J ;: ·· ··· ;' ZapfGmbH + Co. "* *''" ·· ·· ^: 18. Lifting device according to one of claims 1 to 16 characterized in that it has a piston rod (25) connected to the piston (23), which extends upwards through the upper chamber (21) and beyond and is connected to one of the platforms (5, 6). 19. Lifting device according to claim 18, characterized in that both chambers (19, 21) of each lifting cylinder (13) are connected by means of a return line (53), so that only the difference between the lower and upper chambers (19, 21) of the lifting cylinder (13) is stored in the storage device (29, 30, 31, 32). 20. Lifting device according to one of claims 1 to 19, characterized in that a leak-free or essentially leak-free closing valve (49) is provided in the common supply line (43) to the respective second chambers (37) of the storage devices (29, 30, 31, 32).