EP4375228A1 - Lifting device - Google Patents

Abstract

The invention relates to a mobile lifting device (10), which preferably has a chassis (12) with several rollers (13). The lifting device (10) has a closed fluid circuit, in particular a hydraulic circuit. It has a cylinder (21) with a lifting work chamber (23). The lifting work chamber (23) is fluidically connected to a fluid reservoir (26) via a first fluid line (24) and a second fluid line (25). A main pump (45) is arranged in the first fluid line (24), which can be driven by means of a rotary-driven hand tool in order to convey fluid from the fluid reservoir (26) into the lifting work chamber (23), thereby extending a piston rod (32) of the fluid cylinder (21), for example in order to lift a load (20). A flow control arrangement (47) is arranged in the second fluid line (25), which can be switched between a locked state and a released state by means of a lowering control element (48). When the piston rod (32) is extended, the flow control arrangement (47) is in the locked state. When the piston rod (32) is retracted, it is transferred to the released state, whereby fluid can flow out of the lifting chamber (23) through the second fluid line (25).

Description

The invention relates to a lifting device, in particular a mobile and preferably a movable or rollable lifting device. The lifting device is designed to lift a load with fluidic support relative to the ground on which the lifting device stands and to hold it there.

Such lifting devices can be used, for example, in the automotive industry to lift heavy loads during vehicle assembly, position them at a suitable point in the vehicle body and secure them there. For this purpose, known lifting devices have, for example, a foot pedal by means of which a foot pump can be operated so that hydraulic fluid is pumped into a hydraulic cylinder in order to gradually lift it with the load. However, lifting a load over longer distances is relatively strenuous because such lifting devices cover a distance of around 1 cm per foot pedal movement when loaded.

There are also known lifting devices that have a compressed air cylinder for pressure support, which is connected to a stationary compressed air source via a compressed air line. However, the support is low and is used in particular for the rapid compressed air-assisted movement of a piston of the compressed air cylinder when no load needs to be lifted (load-free movement). The The disadvantage of such lifting devices is the required fluid line connection to a compressed air connection in the surrounding area, for example in a building. In a factory, workshop or assembly hall, such fluid lines lying on the floor represent an obstacle and also a safety risk.

Based on such lifting devices known from practice, it can be considered the object of the invention to create a particularly mobile lifting device which can also cover long lifting distances in a simple manner and, moreover, does not require a fluid line connection to an external pressure source.

This object is achieved by a lifting device having the features of patent claim 1.

The lifting device according to the invention has a fluid cylinder. The fluid cylinder has a cylinder housing that surrounds a lifting chamber. A piston is arranged adjacent to the lifting chamber so that it can move in a lifting direction. A piston rod is attached to the piston with its inner end. The outer end of the piston rod, opposite the inner end, protrudes from the cylinder housing and serves there as a support part or has a support part there. The support part is designed to carry or arrange a load. By changing a fluid volume in the lifting chamber, the piston can be moved in the lifting direction in order to extend or retract the piston rod. For this purpose, the lifting chamber is part of a fluid circuit, in particular a closed fluid circuit. The fluid is preferably a liquid, for example a hydraulic oil.

The fluid circuit of the lifting device also has a fluid supply or a fluid reservoir. A first fluid line and a second fluid line each fluidically connect the fluid reservoir and the lifting chamber. The first fluid line and the second fluid line are fluidically connected in parallel to one another.

The lifting device also has a rotary driven pump, which is referred to as the main pump to distinguish it from other optionally available pumps. The main pump is arranged in the first fluid line. In the driven state, the main pump can convey fluid through the first fluid line, in particular from the fluid reservoir via the first fluid line into the lifting chamber in order to extend the piston rod.

The lifting device according to the present invention is designed without a drive and without a motor. A tool interface is provided to drive the main pump, which is connected to the main pump. The tool interface is designed to be connected to a hand tool that can be driven in rotation, so that the main pump can be driven by the hand tool. The hand tool has a motor for this purpose, preferably an electric motor. The hand tool has an internal energy storage device (e.g. rechargeable battery) as an energy source for operating its motor and can therefore be operated without an electrical line connection to the power supply network. The hand tool can be, for example, a (cordless) drill or a cordless screwdriver.

The lifting device according to the present invention also has a flow control arrangement in the second fluid line. The flow control arrangement can be switched between a blocking state and a release state. The switching is carried out by means of a lowering control element that is connected to the flow control arrangement. In the blocking state, a fluid flow from the lifting work chamber via the second fluid line into the fluid reservoir is blocked. In the release state, the fluid flow from the lifting work chamber via the second fluid line into the fluid reservoir is enabled. The flow control arrangement is preferably designed to throttle the fluid flow flowing through the second fluid line in the release state and/or to control or regulate it depending on the volume flow and/or mass flow.

The lifting device can be implemented very easily as a mobile lifting device. Fluid lines to external pressure sources or external fluid circuits (for example in a building) are not required. The lifting device also does not need its own motor. Longer strokes can be covered without any effort or considerable effort by driving the main pump with a hand tool. This means that strokes of 100 cm and more can be covered very quickly. The extension speed under load can be at least 10 cm to 15 cm/s, for example, if the main pump is operated at its rated speed for a fast stroke in the extension direction of the piston rod.

The lifting device therefore works with minimal effort and is easier for the operator to handle. Safety-critical fluid lines to external pressure sources can be omitted. The lifting device also does not require an electrical power supply. It can be designed completely without any line or cable connections.

The main pump is preferably a gear pump. Gear pumps are robust and quiet, so that no loud noises are generated when a load is lifted during use, meaning that labor law regulations can be complied with without any problems.

The fluid cylinder can therefore be a telescopic cylinder. The piston and the piston rod of the lifting device can consist of several parts mounted on one another in a telescopic manner. In this way, a desired working height can be achieved with the piston rod fully retracted and at the same time a large stroke of, for example, 100 cm and more and, in one embodiment, around 120 cm.

The lifting device is preferably designed as a mobile unit such that it can be moved by a single person and positioned at a desired location on a surface. For this purpose, the lifting device can have a frame, a tripod or similar. It is particularly preferred if the lifting device has a chassis with several rollers, for example a chassis with at least 3 to 5 arms and one roller each, similar to an office chair. The lifting device designed as a mobile unit in particular does not have its own drive, but can be moved by an operator by pushing or pulling it over a surface.

In a preferred embodiment, the lifting device has a locking device that can be switched between a locking state and a release state. In the locking state, a relative rotation of the carrier part about a longitudinal axis of the piston rod relative to the chassis is blocked. This locking state is advantageous when the piston rod is fully retracted or is close to its fully retracted position. The lifting device can then be moved or aligned using the carrier part. The chassis also moves relative to the ground. If, on the other hand, the carrier part were rotatable about the longitudinal axis of the piston rod, rotating the carrier part would not cause the chassis to rotate relative to the ground.

In the released state, such a relative rotation of the carrier part around the longitudinal axis of the piston rod relative to the chassis is possible. This is particularly useful when the piston rod is extended, for example fully extended. Then the carrier part (with or without load) can be positioned in relation to its rotational position around the longitudinal axis of the piston rod without this having an effect on the chassis.

It may be advantageous to design the locking device in such a way that it automatically assumes the locking state or can only be brought into the locking state when the piston rod is fully retracted or is close to the fully retracted position. Additionally or alternatively, the locking device can be designed to automatically assume the release state or only be brought into the release state to be brought when the piston rod is a minimum distance away from its fully retracted position. In this way, for example, the locking state can be prevented from being assumed when the piston rod is lifting a load. This is because it is generally undesirable in this position for the lifting device to rotate relative to the ground when the rotational position of the support part is changed about the longitudinal axis of the piston rod.

It is also preferred if one or more of the rollers on the chassis can be secured against rolling movement by means of a brake. The brake can be switched between a braking position and a release position that releases the roller, for example by an operator's foot.

In particular, the fluid circuit of the lifting device is closed and has no fluid connection to an external pressure source or other external fluid circuits, such as a pressure source or a pressure connection in or on a building. All fluid connections required for the use and operation of the lifting device run exclusively within the lifting device and are in particular part of the mobile or movable lifting device.

In one embodiment, the lifting device can have a fluid container which is arranged outside the cylinder housing. The fluid container then has the fluid reservoir. In a preferred embodiment, the fluid container surrounds the cylinder housing (eg coaxially and/or completely in the circumferential direction), so that the fluid reservoir a gap between the fluid container and the cylinder housing. In this embodiment, the fluid reservoir can be an annular space around the cylinder housing.

It is advantageous if the cylinder is a single-acting cylinder that can be extended by filling the lifting chamber using the main pump. In this design, the retraction movement is carried out by the weight force acting on the piston rod, for example the support part and/or a load.

As an alternative to a single-acting cylinder, a double-acting cylinder can also be used. The double-acting cylinder has a lowering working chamber in addition to the lifting working chamber. The piston separates the two working chambers from each other fluidically. In this design, a retraction movement of the piston rod can be actively supported by applying pressure to the lowering working chamber. Preferably, the lowering working chamber forms the fluid reservoir at least partially or completely. A fluid container separate from the cylinder housing can be omitted in this design, but can optionally be present.

If the cylinder is a double-acting cylinder, the main pump can pump fluid in two directions through the first fluid line, i.e. from the lowering chamber into the lifting chamber and vice versa from the lifting chamber into the lowering chamber, depending on the direction of rotation of the main pump.

It is advantageous if a third Fluid line is present which is fluidically connected parallel to the first fluid line and the second fluid line. An additional pump can be present in the third fluid line. In particular, the additional pump is a pump operated by muscle power, in particular a foot pump. For operation, a pump control element is provided which can be designed as a foot pedal, for example. By operating the additional pump using the pump control element, fluid can be pumped through the third fluid line from the fluid reservoir into the lifting chamber. For example, the additional pump is used to make a finer, more precise adjustment of the desired lifting position, while the main pump mainly carries out a rapid lifting movement. The additional pump can, for example, be set up so that with each complete pumping movement of the pump control element of the additional pump, the piston rod or the carrier part travels a maximum distance of 5 cm or 3 cm or 2 cm or 1 cm in the lifting direction when the carrier part is loaded with the nominal load or maximum load.

It is preferred if the lowering control element and/or the pump control element is a foot pedal designed for actuation with a foot. Such a foot pedal is arranged in the region of the vertically lower end of the fluid cylinder so that it can be reached with the foot of an operator standing nearby and is preferably arranged at a distance from the ground in every actuation position when actuated with the foot.

The flow control arrangement is preferably designed such that when the lowering control element is operated to lower a load or the support part without a load, a predetermined lowering speed is achieved or the lowering speed is at least within a predetermined speed range. In one embodiment, a lowering speed of 10 cm/s to 20 cm/s can be specified or set, for example 15 cm/s, when the carrier part is loaded with a nominal load or a maximum load.

The nominal load of the support part is the load for which the lifting device is designed. At nominal load, the lifting device preferably operates in an ideal operating state for which the components of the lifting device are designed and/or adjusted. The maximum load is the maximum load that can be placed on the support part.

In one embodiment, the flow control arrangement can have a valve that can be switched to switch the flow control arrangement between the blocking state and the release state. The switchable valve can be, for example, a releasable check valve or a directional valve (in particular 2/2-way valve). The switchable valve can block in the initial state (blocking state of the flow control arrangement), for example be mechanically preloaded into the initial state. The switchable valve can be opened by means of the lowering control element in order to allow a defined fluid flow (release state of the flow control arrangement).

In an advantageous embodiment, the flow control arrangement is designed to adjust the fluid flow in the release state to a target flow value or a target flow range, in particular to regulate it automatically. For example, the flow control arrangement For this purpose, they must have a pressure compensator, which is also called a differential pressure valve.

Advantageous embodiments of the invention emerge from the dependent patent claims, the description and the drawing. Advantageous embodiments are explained in detail below with reference to the drawing. The drawing shows:

Figure 1 a perspective view of an embodiment of a mobile lifting device according to the present invention,

Figure 2 the lifting device Figure 1 with the housing cover partially removed,

Figure 3 a block diagram-like schematic representation of an embodiment of a lifting device according to the invention with a single-acting cylinder,

Figure 4 a block diagram-like schematic representation of a lifting device according to the invention with a double-acting cylinder,

Figures 5 to 7 each a circuit diagram for a fluid circuit for any embodiment of the lifting device with a single or double acting cylinder and

Figure 8 a schematic diagram of a telescopic cylinder that can be used in any embodiment of the lifting device.

In the Figures 1 and 2 an embodiment of a lifting device 10 is illustrated. The lifting device 10 is designed as a mobile unit 11 for moving on a surface (in particular the floor). For this purpose, the lifting device 10 has a chassis 12 with several rollers 13, in particular at least three rollers 13 and, for example, five rollers 13 are present. In the Figures 1 and 2 Each roller 13 is arranged on an arm 14 of the chassis 12, whereby a total of five arms 14 with one roller 13 each are present. One of the arms 14 is in the perspective view of the Figures 1 and 2 not recognizable.

One or more of the rollers 13 can be pivotably mounted about a pivot axis S, wherein the pivot axes S extend parallel to one another, in particular in a lifting direction H of the lifting device. The lifting direction H is essentially oriented vertically when the lifting device 10 is in a ready-to-use state and, for example, the chassis 12 is set up on a surface.

The chassis 12 can be designed similarly to the frame of a swivel chair or office chair ( Figures 1 and 2 ). Alternatively, the chassis 12 can also have a different arrangement of the rollers 13, for example three or four rollers that carry a plate or another base body of the chassis 12, similar to shopping carts or industrial trucks that can be moved using muscle power ( Figures 3 and 4 ).

By means of the chassis 12, the lifting device 10 can be moved relative to a surface to the desired location and positioned there. Preferably, at least one of the existing rollers 13 is assigned a brake 15, which secures the assigned roller 13 in a braking state against turning or rolling on the ground. The brake 15 can be actuated, for example, with the foot of an operator in order to switch it to the braking state and to the release state.

As an alternative to the illustrated embodiment according to the Figures 1 to 4 the rollers 13 on the chassis 12 could also be movable between a support position and a retracted position. In the support position, they support the lifting device on the ground in a rolling manner, while in the retracted position they allow frictional contact between frame parts of the chassis and the ground, so that a rolling movement is no longer possible due to the friction that occurs between frame parts and the ground.

The lifting device 10 according to the present invention is designed in particular for lifting a load 20 in the lifting direction H. The lifting device can be, for example, a transmission jack, which is used in the automotive industry for lifting a transmission vertically upwards into a vehicle body in order to connect the transmission in the vehicle body to other vehicle parts. The lifting device could also be designed in the manner of a lifting table for other loads 20.

The lifting device 10 has a closed fluid circuit in all embodiments. Embodiments of the fluid circuit are shown in the Figures 3 to 7 shown.

The lifting device 10 has a fluid cylinder 21 (cf. Figures 3 to 7 ). The fluid cylinder 21 can be a single-acting cylinder ( Figures 3 , 5 6 and 7 ) or a double-acting cylinder (schematically shown dash-dotted variation in the Figures 4 to 7 ). It has a cylinder housing 22 in which a lifting work chamber 23 is present. The lifting work chamber 23 is fluidically connected to a fluid reservoir 26 by means of a first fluid line 24 and by means of a second fluid line 25 connected in parallel thereto. In the preferred embodiments illustrated here, a third fluid line 27 is also present, which is connected in parallel to the first fluid line 24 and the second fluid line 25 and thus also creates a fluid connection between the lifting work chamber 23 and the fluid reservoir 26.

It should be noted at this point that the fluid lines 24, 25, 27 establish a fluid connection, but do not have to permanently allow fluid flow through the fluid line in question. This depends on the condition of the components arranged in the respective fluid line 24, 25, 27.

The lifting chamber 23 in the cylinder housing 22 is fluidically sealed in the stroke direction H on one side by a piston 31 that is movably mounted in the stroke direction H in the cylinder housing 22. A piston rod 32 is attached to the piston 31 with an inner end 33. The piston rod 32 extends from the inner end 33 in the stroke direction H to an opposite outer end 34. At the outer end 34, the piston rod 32 forms a carrier part 35 or is connected to a carrier part 35. For example only, in the Figures 3 and 4 a plate-shaped or table-top-shaped support part 35 is shown, on which the load 20 can be arranged. The type and design of the support part 35 varies depending on the application and the type of load 20 to be lifted. The support part 35 is used to arrange the load on the lifting device 10 and is designed according to the load 20 to be lifted. It is also possible to provide several interchangeable support parts 35 of different designs in the manner of a modular system, which can optionally be releasably attached to the outer end 34 of the piston rod 32 via a defined attachment interface.

The outer end 34 of the piston rod 32 is located outside the cylinder housing 22 in every position of the piston 31.

In some embodiments, the fluid cylinder 21 is a single-acting cylinder. The area within the cylinder housing 22, which surrounds the piston rod 32 and is fluidically separated from the lifting chamber 23 by means of the piston 31, does not have to be fluidically sealed from the surroundings of the lifting device 10 in this embodiment. The fluid reservoir 26 is arranged outside the cylinder housing 22 in this embodiment, for example in a separate fluid container 39. In order to achieve a compact design of the lifting device 10, the fluid container 39 in the embodiments according to the Figures 1 to 3 arranged around the cylinder housing 22 and can completely enclose it in the circumferential direction around the stroke direction H. A gap 40 between the cylinder housing 22 and the fluid container 39 forms the fluid reservoir 26 in this embodiment. The intermediate space 40 or the fluid reservoir 26 can be an annular space that coaxially encloses a longitudinal axis of the piston rod 32. The annular space can have a hollow cylindrical shape. However, it is also possible to align the fluid container 39 and the cylinder housing 22 non-coaxially with one another.

As it is in the Figures 1 and 2 As can be seen, a fluid connection 41 (e.g. filler neck) can be present on the fluid container 39 for filling and/or refilling a fluid, for example on a lid or in a side wall of the fluid container 39.

In particular, Figure 4 It can be seen that the cylinder 21 can also be designed as a double-acting cylinder. In these embodiments, it has a lowering chamber 42 in addition to the lifting chamber 23. The piston 31 fluidically separates the lifting chamber 23 from the lowering chamber 42 in the cylinder housing 22. In this embodiment, at least part of the fluid reservoir or the entire fluid reservoir 26 is formed by the lowering chamber 42. A fluid container separate from the fluid cylinder 21 can be omitted in this embodiment, but can optionally be present, as shown in dashed lines in Figure 4 is shown.

Since the lowering chamber 42 represents at least part or all of the fluid reservoir 26, the fluid lines 24, 25, 27 in the double-acting cylinder according to Figure 4 the lowering chamber 42 is fluidically connected to the lifting chamber 23.

In all embodiments, a main pump 45 that can be driven in rotation is arranged in the first fluid line 24. The main pump 45 is designed to cause a fluid flow through the first fluid line 24 in the driven state, at least in one direction from the fluid reservoir 26 to the lifting work chamber 23. This allows fluid to be conveyed into the lifting work chamber 23 and the piston 31 to be moved in the stroke direction H to extend the piston rod 32. In this way, a load 20 can be lifted. In the case of a double-acting cylinder 21, the main pump 45 can also be driven in rotation in the opposite direction of rotation in order to convey a fluid from the lifting work chamber 23 into the lowering work chamber 42. In this way, a retraction movement of the piston rod 32 can be supported.

The lifting device 10 does not have its own motor. To drive the main pump 45, it has a tool interface 46 which is designed to connect a rotary-driven hand tool, for example a cordless drill or a cordless screwdriver, to the main pump 45. The tool interface 46 can be designed as an external hexagon, for example. In general, however, all known polygonal and/or multi-surface standardized tool interfaces can also be used, for example a slotted connection, a Phillips connection, an internal hexagon, an external or internal square, a six-tooth or "TORX" connection, etc. The tool interface 46 is arranged so that it is accessible from the outside in order to connect the hand tool to the tool interface 46.

In the second fluid line 25, a flow control arrangement 47 is arranged, which by means of a lowering control element 48 can be switched from a blocking state to a release state. In the blocking state, fluid can flow from the lifting work chamber 23 via the second fluid line 25 into the fluid reservoir 26, while the flow control arrangement 47 prevents such a fluid flow in the blocking state.

In the optionally available third fluid line 27, for example, an additional pump 49 is arranged, which can be operated, for example, with muscle power via a pump control element 50. When the pump control element 50 is operated with muscle power, the additional pump 49 causes a fluid flow from the fluid reservoir 26 through the third fluid line 27 into the lifting chamber 23. By means of the optionally available additional pump 49, for example, a finer, more precise positioning of the carrier part 35 or the load 20 in the lifting direction H can be achieved.

In the embodiment illustrated here, both the lowering control element 48 and the pump control element 50 are designed as foot pedals, as is particularly the case in the Figures 1 and 2 can be seen. The foot pedals are arranged at the bottom of the chassis 12 so that they can be easily reached with the foot when the operator is standing on the ground next to the lifting device 10.

In the Figures 3 and 4 the fluid cylinder 21 is illustrated with an integral rod-shaped piston rod 32. Figure 8 shows schematically in the form of a block diagram a telescopic cylinder 51, as it can be used in all embodiments of the lifting device 10. The telescopic cylinder 51 has a telescopic Piston rod 32 consists of several piston rod sections 32a, 32b, 32c, each of which is firmly connected to an associated piston section 31a, 31b, 31c. The number of piston rod sections and piston sections can vary. With a telescopic cylinder 51, a larger stroke in stroke direction H can be achieved with a compact design than with a single integrally formed piston rod 32. The telescopic cylinder 51 can be designed in the form of a single-acting telescopic cylinder or a double-acting telescopic cylinder (shown in dashed lines).

In the Figures 5 to 7 Different embodiments of the fluid circuit for the lifting device 10 are shown, which can be used for a single-acting cylinder (solid and dashed lines) or a double-acting cylinder (optional dash-dotted lines) regardless of the other design of the lifting device 10.

In the Figure 5 In the embodiment shown, a check valve 52 is arranged in the first fluid line 24 and in the optionally available third fluid line 27 in order to prevent an unwanted outflow of fluid from the lifting work chamber 23 through the first fluid line 24 or the third fluid line 27 to the fluid reservoir 26. The check valves 52 allow fluid to be conveyed by the main pump 45 or the additional pump 49 into the lifting work chamber 23, but prevent an unwanted outflow from the lifting work chamber 23 via the relevant fluid line 24, 27.

In the Figure 5 illustrated embodiment the flow control arrangement 47 in the second fluid line 25 has a valve 53 that can be switched by means of the lowering control element 48, for example an unlockable check valve. It also has a throttle 54 connected in series with it. In its unactuated state, the switchable valve 53 is in its blocking position and blocks fluid from flowing out of the lifting work chamber 23 into the fluid reservoir 26 via the second fluid line 25. If the switchable valve 53 is opened by actuating the lowering control element 48, the flow control arrangement 47 is in its release state and allows fluid to flow out of the lifting work chamber 23 through the second fluid line 25 into the fluid reservoir 26. The flow is limited by the optionally present throttle 54 in order to prevent the piston rod 32 from retracting too quickly, in particular when a load 20 is arranged on the carrier part 35. The throttle 54 can optionally be designed as an adjustable throttle or a pressure-dependent throttle. The throttle 54 can additionally or alternatively also be a component of the switchable valve 53.

This in Figure 6 The embodiment of the fluid circuit shown differs from the embodiment according to Figure 5 exclusively in the design of the flow control arrangement 47. In this embodiment, the flow control arrangement 47 has a flow-controlled valve arrangement 55. This valve arrangement 55 includes a valve 53 that can be switched between two switching positions by means of the lowering control element 48, which here is, for example, a directional control valve 56, as well as a pressure compensator or a differential pressure valve 57.

The directional control valve 56 and the differential pressure valve 57 are fluidically connected in series in the second fluid line 25. The differential pressure valve 57 detects the pressure upstream of the directional control valve 56 and the pressure downstream of the differential pressure valve 57 and sets them to a predetermined target differential pressure. The differential pressure applied to the directional control valve 56 is therefore constant when fluid flows from the lifting chamber 23 through the flow control arrangement 47 to the fluid reservoir 26 to retract the piston rod 32. The directional control valve 56 can specify the flow in the release state of the flow control arrangement 47 by throttling and optionally adjustable throttling. By keeping the differential pressure constant via the differential pressure valve 57, a desired volume flow can be set. This allows the speed of the retraction movement of the piston rod 32 to be set regardless of the load.

Otherwise, the embodiment of the fluid circuit according to Figure 6 the embodiment of Figure 5, so that reference can be made to the above description.

In Figure 7 A further embodiment of the fluid circuit for the lifting device 10 is illustrated. The fluid circuit has a further check valve 52 between the lifting work chamber 23 and a connection point 58, which prevents a flow from the lifting work chamber 23 in the direction of the connection point 58. The second fluid line 25 is, as before, directly fluidically connected to the lifting work chamber 23.

At connection point 58 is the main pump 45. The pressure provided by the optional additional pump 49 is also present at this connection point. The connection point 58 is connected to the fluid reservoir 26 via an overpressure branch 59. A preferably adjustable overpressure valve 60 is arranged in the overpressure branch 59. The overpressure valve 60 opens at a set maximum pressure value and thus limits the pressure provided by the main pump 45 and/or the additional pump 49 at the connection point 58 to a predetermined and preferably adjustable maximum pressure.

This embodiment with an additional check valve 52 and the overpressure branch 59 can be used in all embodiments of the fluid circuit.

The modified design of the flow control arrangement 47 as shown in Figure 7 can also be used in all embodiments of the fluid circuit. Similar to the embodiment according to Figure 6 the flow control arrangement 47 has a switchable valve 53, which here is a directional valve 56, and in series with it a throttle 54. In contrast to the embodiment according to Figure 6 the pressure compensator or differential pressure valve 57 is omitted. The throttle 54 is arranged separately from the directional valve 56 in the second fluid line 25. Alternatively, the throttle 54 could also be integrated into the directional valve 56, similar to the embodiment according to Figure 6 .

The Figures 5 to 7 The fluid circuits shown for the single-acting cylinder 21 can be used for a double-acting cylinder, as shown schematically in dash-dotted lines. For example, the check valve 52 arranged in fluid series with the main pump 45 in the first fluid line 24 can be designed as a releasable check valve that can be unlocked or opened by actuating the lowering control element 48. Then, by means of the main pump 45, fluid can also be conveyed through the first fluid line 24 from the lifting work chamber 23 into the fluid reservoir 26 formed by the lowering work chamber 42, in particular to support a retraction movement of the piston rod 32, for example in the load-free state without load 20. In this case, the main pump 45 can be driven to rotate in both directions of rotation in order to reverse the conveying direction for extending and retracting the piston rod 32.

Another option that can be used in all embodiments of the lifting device 10 is shown in a highly schematic manner in Figures 3 and 4 The lifting device 10 can additionally have a locking device 65 which can be switched between a locking state and a release state. In the locking state, the locking device 65 blocks rotation of the carrier part 35 and/or the piston rod 32 about a longitudinal axis of the piston rod 32 relative to the cylinder housing 22 and/or the fluid container 39 and/or any other component of the lifting device 10 which is connected to the chassis 12 in a rotationally fixed manner about the longitudinal axis of the piston rod 32. The locking state of the locking device 65 can be established automatically or manually when the piston rod 32 is in its fully retracted position or at least is only far enough away from the fully retracted position that a minimum extension path in stroke direction H has not yet been covered.

For example, the locking device 65 can have a locking body that is arranged on the outer end 34 and/or on the support part 35 and, in the locked state, is present in an associated locking recess on the cylinder housing 22 and/or on the fluid container 39 and/or any other part that is connected to the chassis 12 in a rotationally fixed manner. In this locked state, the support part 35 (e.g. table, support plate, support frame, etc.) can be grasped by an operator and the lifting device 10 can be moved along the base via the support part 35 and also rotated in the process. In the locked state, only the support part 35 is prevented from rotating about the longitudinal axis of the piston rod 32 and the position of the chassis 12 relative to the base is changed little or not at all.

In the release state of the locking device 65, such a rotation of the carrier part 35 relative to the cylinder housing 22 or the fluid container 39 or the chassis 12 is permitted. For example, the locking body is disengaged from the associated locking recess. The release state can be reached automatically, for example, when the piston rod 32 is extended so far from its fully retracted position that the locking body no longer engages in the locking recess.

The embodiments of the lifting device 10 described so far can be used as follows:

It is assumed that by means of the lifting device 10 a load 20 is to be lifted. To load the carrier part 35 with the load 20, the piston rod 32 is preferably first brought into its fully retracted position. The carrier part 35 for receiving the load 20 is then in a low position and can be loaded very easily.

After loading, the lifting device 10 with the load 20 can be moved to the desired position by driving or rolling the mobile lifting device 10 over the ground using the chassis 12. If a locking device 65 is present, this is preferably in the locked state so that the mobile unit can be moved and rotated, for example, via the carrier part 35. If a locking device 65 is not present, a handle 66 is preferably present, which is connected in a rotationally fixed manner in the circumferential direction around the longitudinal axis of the piston rod to some component of the lifting device 10, which in turn is connected in a rotationally fixed manner to the chassis 12, for example the cylinder housing 22 and/or the fluid container 39 ( Figures 1 and 2 ).

After the lifting device 10 has been positioned at the desired location, one or more of the rollers 13 are preferably secured against rolling movement, for example by means of the brake 15.

Subsequently, for a rapid lift of the load 20 in the lifting direction H, the piston rod 32 can be driven by driving the main pump 45 using a hand tool (drill, cordless screwdriver). The main pump 45 pumps fluid into the lifting chamber 23. This rapid lift can lift the load 20 at least in the approximately desired height in a short time. In this case, extension speeds of the piston rod 32 of, for example, at least 10 cm/s or at least 15 cm/s or more can be achieved.

For fine adjustment of the position of the load 20 in the lifting direction H, the additional pump 49 operated by muscle power is optionally available. With each stroke of the pump control element 50 designed as a foot pedal, so little fluid is pumped into the lifting chamber 23 that the load 20 is only raised a few millimeters, for example a maximum of 10 mm with each operating movement or pumping movement via the pump control element 50. In this way, the load 20 can be arranged very precisely in the lifting direction H at the desired height. Depending on the type of application and the load 20, it can be transported further at the raised height and/or assembled and/or used in another way.

After further transport and/or assembly of the load 20, the carrier part 35 can be lowered again by retracting the piston rod 32. For this purpose, in the exemplary embodiment, the lowering control element 48 is actuated so that fluid can flow out of the lifting chamber 23 into the fluid reservoir 26.

The mobile lifting device 10 can then be moved along the ground again to pick up another load 20. The process is then carried out again as described.

The lifting device 10 is also suitable for applications where a load 20 is to be lifted at a certain height with the lifting device partially or fully extended. Piston rod 32 is picked up and then lowered and transported away by means of the lifting device 10.

The invention relates to a mobile lifting device 10, which preferably has a chassis 12 with several rollers 13. The lifting device 10 has a closed fluid circuit, in particular a hydraulic circuit. It has a cylinder 21 with a lifting work chamber 23. The lifting work chamber 23 is fluidically connected to a fluid reservoir 26 via a first fluid line 24 and a second fluid line 25. A main pump 45 is arranged in the first fluid line 24, which can be driven by means of a rotary-driven hand tool in order to convey fluid from the fluid reservoir 26 into the lifting work chamber 23, thereby extending a piston rod 32 of the fluid cylinder 21, for example in order to lift a load 20. A flow control arrangement 47 is arranged in the second fluid line 25, which can be switched between a locked state and a released state by means of a lowering control element 48. When the piston rod 32 is extended, the flow control arrangement 47 is in the locked state. To retract the piston rod 32, it is transferred to the released state, whereby fluid can flow out of the lifting chamber 23 through the second fluid line 25.

List of reference symbols:

10

Lifting device

11

mobile unit

12

chassis

13

role

14

poor

15

brake

20

load

21

Fluid cylinder

22

Cylinder housing

23

Lifting chamber

24

first fluid line

25

second fluid line

26

Fluid reservoir

27

third fluid line

31

Pistons

31a

Piston section of the telescopic cylinder

31b

Piston section of the telescopic cylinder

31c

Piston section of the telescopic cylinder

32

Piston rod

32a

Piston rod section of the telescopic cylinder

32b

Piston rod section of the telescopic cylinder

32c

Piston rod section of the telescopic cylinder

33

inner end

34

outer end

35

Carrier part

39

Fluid container

40

Space

41

Fluid connection

42

Lowering chamber

42a

Lowering working chamber section of the telescopic cylinder

42b

Lowering working chamber section of the telescopic cylinder

42c

Lowering working chamber section of the telescopic cylinder

45

Main pump

46

Tool interface

47

Flow control arrangement

48

Lowering control element

49

Additional pump

50

Pump control element

51

Telescopic cylinder

52

check valve

53

switchable valve

54

throttle

55

Valve arrangement

56

Directional valve

57

Differential pressure valve

58

Connection point

59

Overpressure branch

60

Pressure relief valve

65

Locking device

66

Handle

H

Stroke direction

S

Swivel axis

Claims (15)

Lifting device (10) comprising: - a fluid cylinder (21) having a cylinder housing (22), a lifting chamber (23) in the cylinder housing (22), a piston (31) and a piston rod (32) which is attached to the piston (31) with an inner end (33) and which protrudes from the cylinder housing (22) with an outer end (34) and has a support part (35) there for carrying a load (20), wherein the piston (21) adjoins the lifting chamber (23) and wherein the piston (31) and the piston rod (32) are mounted so as to be movable in a lifting direction (H), - a fluid reservoir (26), - a first fluid line (24) and a second fluid line (25), each of which fluidically connects the fluid reservoir (26) and the lifting chamber (23), - a main pump (45) which can be driven in rotation in the first fluid line (24) and which is designed, in the driven state, to convey fluid from the fluid reservoir (26) via the first fluid line (24) into the lifting chamber (23), - a tool interface (46) which is drive-connected to the main pump (45) and is adapted to be connected to a rotary-driven hand tool in order to drive the main pump (45), - a flow control arrangement (47) in the second fluid line (25) which, in a blocking state, controls a fluid flow from the lifting chamber (23) via the second fluid line (25) into the fluid reservoir (26) and in a release state allows a fluid flow from the lifting chamber (23) via the second fluid line (25) into the fluid reservoir (26), and - a lowering control element (48) connected to the flow control arrangement (47) and adapted to switch the flow control arrangement (47) between the locked state and the released state. Lifting device according to claim 1, which is designed as a mobile unit such that it can be moved by a single person and positioned at a desired location on a surface. Lifting device according to claim 2, further comprising a chassis (12) with a plurality of rollers (13), so that the lifting device (10) is designed as a rollable unit. Lifting device according to claim 3, further comprising a locking device (65) which, in a locking state, blocks a relative rotation of the carrier part (35) about a longitudinal axis of the piston rod (32) relative to the chassis (12) and allows the relative rotation of the carrier part (35) about the longitudinal axis of the piston rod (32) relative to the chassis (12) in a release state. Lifting device according to claim 4, wherein the locking device (65) automatically assumes the locking state or can be brought into the locking state when the piston rod (32) is retracted, in particular completely retracted. Lifting device according to claim 4 or 5, wherein the locking device (65) automatically assumes the release state or can be brought into the release state when the piston rod (32) is located a minimum distance away from its fully retracted position. Lifting device according to one of the preceding claims, further comprising a fluid container (39) surrounding the cylinder housing (22), wherein the fluid reservoir (26) is a gap (40) between the fluid container (39) and the cylinder housing (22). Lifting device according to one of the preceding claims, wherein the cylinder (21) is a single-acting cylinder. Lifting device according to one of claims 1 to 8, wherein the cylinder (21) is a double-acting cylinder, wherein the piston (31) is arranged between a lowering working chamber (42) and the lifting working chamber (23) and wherein the fluid reservoir (26) is completely or partially the lowering working chamber (42). Lifting device according to claim 9, wherein the main pump (45) is designed to convey fluid from the lowering work chamber (42) into the lifting work chamber (23) via the first fluid line (24) in the driven state in one direction of rotation and to convey fluid from the lifting work chamber (23) into the lowering work chamber (42) via the first fluid line (24) in the driven state in an opposite direction of rotation. Lifting device according to one of the preceding claims, further comprising a third fluid line (27) which fluidically connects the fluid reservoir (26) and the lifting work chamber (23), an additional pump (49) in the third fluid line (27) and a pump operating element (50) designed for operation by means of muscle power for actuating the additional pump (49), wherein the additional pump (49) is designed, in the actuated state, to convey fluid from the fluid reservoir (26) via the third fluid line (27) into the lifting work chamber (23). Lifting device according to claim 11, wherein the pump operating element (50) is a foot pedal adapted for actuation with a foot. Lifting device according to one of the preceding claims, wherein the lowering control element (48) is a foot pedal designed for actuation with a foot. Lifting device according to one of the preceding claims, wherein the flow control arrangement (47) has a valve (53, 56) which can be switched between the blocking state and the release state by means of the lowering control element (48). Lifting device according to one of the preceding claims, wherein the flow control arrangement (47) comprises a flow-controlled valve arrangement (55).

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