EP1680603B1 - Hydraulic double ram lifting platform - Google Patents

Abstract

The invention relates to a hydraulic double ram lifting platform with two cylinder tubes (3), moving together in the vertical direction (17), a hydraulically-operated lifting unit (18), for each cylinder tube (3), a mechanical cross-support (5), for both lifting units (18) to ensure synchronization of both cylinder tubes (3) and rotational fixing about the longitudinal axis thereof, characterized in that each lifting unit (18) is provided with a standing, hollow plunger piston (4), supported at the base, within which compressed air (26) and a hydraulic fluid (27) are arranged, the interior of which is embodied as a pressurized reservoir and to the lower end of which a curved tube is fixed, which extends inside up to the upper reaches (22) of the plunger piston (4).

Description

TECHNICAL AREA

The invention relates to a 2-ram lift, as used for lifting of motor vehicle lifts in motor vehicle workshops. The 2-Stempelhebühne is installed under the floor in the workshop floor, so that in the retracted state only the motor vehicle recording means can be seen.

Such a lift is from the DE-A-19824081 known.

The vehicles can be lifted by means of the 2-ram lift different levels to facilitate accessibility below the vehicle. A pit under the vehicle thus does not need to be present.

STATE OF THE ART

2-ram lifts of the type mentioned above consist of two hydraulic cylinders arranged side by side in the longitudinal direction of the vehicle, a device for ensuring the synchronization of the two hydraulic cylinders, a lowering safeguard which prevents the two hydraulic cylinders from unintentionally lowering and a drive unit. Furthermore, a lift control and recording media for lifting the vehicle.

Hydraulic cylinders, synchronization device, anti-jacking device and often also the drive unit are installed in a watertight installation cassette.

The lift control is usually located on the front or side of the lift workstation. The two recording media are on the extending parts of the Screwed hydraulic cylinder and are in the retracted state on the workshop floor.

The use of built-in cassettes has the advantage that in the factory a large-scale assembly of parts and assemblies done and thus a comprehensive function and quality control can be performed. The installation, assembly and commissioning of the lift on site is thereby considerably simplified and facilitated.

Modern 2-ram lifts are designed as a reversing cylinder. They work in the so-called high pressure area, i. the operating pressure is usually over 100 bar. When reverse cylinder principle, the two piston rods - also called plunger - remain on the bottom of the mounting cassette. The outside with a smooth surface provided cylinder tubes go through guides, which are bolted to the top of the mounting cassette from. In this way, it is very easy to connect the two extending cylinder tubes with a one- or multi-part cross-connection. This single or multi-part cross-connection ensures the synchronization of the two cylinder tubes and also prevents each of the two cylinder tube can rotate about its own longitudinal axis.

The drive of the lift is usually electro-hydraulic. Hydraulic oil is usually used as the hydraulic medium. Since hydraulic oil is a water polluting liquid, the built-in cassettes are manufactured in dense form. If hydraulic oil escapes (eg in the case of leaks or leaks), the installation cassette serves as a catchment room, which must be regularly checked in accordance with regional regulations and checked for leaks. Built-in cassettes are those made of steel and those made of plastic. Made of steel have the advantage that they are stable for transport, but when installed, the risk of corrosion, which is problematic when using oil as a hydraulic medium from an environmental point of view. The made of plastic are largely corrosion-resistant when installed. Transport, however, represents a considerable risk of damage and thus also environmental risk.

The drive unit of the lift is usually equipped with an electric motor. Depending on the local conditions - single-phase or three-phase network - and the existing power supply, an adjustment of the electric motor and possibly also the lift control is necessary.

The patent DE 198 24 08 1 C2 shows a 2-ram lift of this type with reversing cylinders in electro-hydraulic design. The standing plungers are made of solid material, ie they are not hollow inside, eg formed as a tube. In particular, they do not serve to store the hydraulic fluid.

The disadvantages of the prior art are that needed for the operation of lifts of this kind electrical energy and is used as a hydraulic medium oil that has environmentally hazardous properties. There are also known versions of lifts of this type, which are driven by compressed air. However, then a so-called separate intermediate oil tank is required as a pressure vessel in which the required hydraulic fluid is stored for extending in the lowered state of the lift. In this pressure vessel is fed to start the lift compressed air and removed the hydraulic fluid required for the stroke volume. This pressure vessel requires a relatively large volume and hinders its placement. Either it blocks space within the workshop or it must be installed under the hall, which causes further costs and environmental risks. In addition, piping or hoses between the two lifting units and the intermediate oil tank is needed, flows through the hydraulic fluid. These pipes or hoses in turn are subject to corrosion or aging and their installation increases assembly time and installation costs.

The publication 1 431 975 shows a pneumatic-hydraulic lifting unit in which the hydraulic fluid is stored within the lifting unit. The disadvantage of this prior art is that two seals are required per lifting unit and at the lower end of the extending part of the lifting unit no mechanical coupling for a forced synchronization can be attached when the lifting unit z. B. is to be used for a two-stamp lift.

The German Utility Model DE-GM 1 933 273 shows a pneumatic-hydraulic lifting cylinder, in which the hydraulic fluid is housed in the extending plunger. The disadvantages of this prior art are that it is necessary for the control valve to be located inside the plunger and for the control valve to be actuated to have a movable control line inside the plunger. Also in this lifting cylinder, no mechanical coupling for a forced synchronization can be attached to the lower end of the extending part of the lifting unit when the lifting unit z. B. is to be used for a two-stamp lift.

The object of the invention is to propose a pneumatic hydraulic two-station lift, which is safe and easy to service, which manages with little space and their production with reduced effort and reduced costs is possible. This object is achieved on the basis of the prior art by the appropriate embodiment of a novel pneumatic-hydraulic reversing cylinder.

BRIEF DESCRIPTION OF THE DRAWING

Fig. 1

eine schematisierte, teilweise geschnittene Ansicht der erfindungsgemäßen Hebebühne in fast vollständig abgesenktem Zustand

Fig. 2

eine schematisierte, teilweise geschnittene Ansicht der erfindungsgemäßen Hebebühne im ausgefahrenem Zustand

Fig. 3

ein schematisierter Schaltplan der pneumatischen, hydraulischen und mechanischen Funktionen

The invention will be described and explained in more detail below with reference to the embodiment shown in the drawing. Show it:

Fig. 1

a schematic, partially sectioned view of the lift according to the invention in almost completely lowered state

Fig. 2

a schematic, partially sectioned view of the lift according to the invention in the extended state

Fig. 3

a schematic diagram of the pneumatic, hydraulic and mechanical functions

PRESENTATION OF THE INVENTION

Based on this prior art, the present invention seeks to provide a technically improved 2-ram lift of the type mentioned. This invention is realized by the features of claim 1.

The 2-post lift according to the invention is characterized once by the fact that it is pneumatically driven, but still operated fully hydraulically. Fully hydraulic means in this case, located in the interior of the two cylinder tubes - just like the electro-hydraulic drive - only the hydraulic fluid as a medium, no compressed air.

However, it is not oil-hydraulic and electrically driven, but water-hydraulically and pneumatically driven. Since no water-endangering hydraulic medium is used, eliminates the entire environmental issues and the associated protection and precautionary measures that must prevent that subsets of water-polluting hydraulic medium can escape from the hydraulic circuit and the mounting cassette must then serve as a dense collection space.

Regardless locally different electrical supplies everywhere the same technical design of the lift can be delivered and installed. Since the lift operator manual and the switching of the valves and safety devices is pneumatic, can be completely dispensed with electrical power connections.

The requirements for the quality of the installation cassette are reduced. It is no longer required to be monitored and checked for leaks.

The 2-post lift according to the invention has a built-in cassette (1), which is installed under the floor and filled with soil, sand, gravel and lean concrete (20). On both sides of the mounting cassette (19) guides (2) are screwed, through which the two cylinder tubes (3) hydraulically up and down (17). The cylinder tubes (3) have at the bottom against the standing plunger (4) inside a seal (21). The cylinder tubes (3) are coupled to one another at their lower end (25), below the connection possibility (8) by means of a one-part or multipart cross-beam (5), so that a forced synchronization is created. The plungers (4) are hollow inside. At its lower end (24) a bent tube (6) is attached to the opening (6a). This bent tube (6) is located in the interior of the plunger (4) and extends into the uppermost region (22) of the plunger (4). This curved tube (6) and is open at the top (23). Through this curved tube (6) compressed air (26) is passed into the uppermost region of the plunger (22). The plungers (4) are in the retracted state to its upper region (22) and to just below the upper opening (23) of the bent tube (6) with hydraulic fluid (27), preferably filled with water. The hydraulic fluid water (27) can be added additives that are environmentally friendly, counteract the development of odors and corrosion of metallic materials and promote a reduction in friction in sliding bearings and seals. Instead of water, other organic liquids can be used as hydraulic fluid (27), which are similarly environmentally friendly, such as alcohol.

At the lower end of the plunger (24) there is an opening (7a) with a connection possibility (7) and also at the lower end of the cylinder tubes (25) are located on the cylinder tubes (3) each have a further opening (8a) with a connection possibility ( 8th). These openings (7a, 8a) have connection possibilities (7, 8) for pipe or hose lines.

In accordance with the safety standards of the individual countries to be implemented, there are different designs for two-station hydraulic lifts of this type. Such with a common hydraulic valve (9) for both lifting units (18) and also with two hydraulic valves. There are also versions with mechanical lowering protection (10) and without mechanical lowering protection (10). Shown is the embodiment with a hydraulic valve (9) and with mechanical lowering protection (10).

However, it is always the case that at least one of the two hydraulic lines (11) or (12) has to be designed to be movable either between the hydraulic valve (9) and the support piston (3) or between the hydraulic valve (9) and the plunger (4). The interiors of the plunger (4) act as a kind of intermediate liquid container and store the necessary amount of liquid required to operate the lift. The Operation of the lift takes place in the illustrated case via a lever control (13) according to the deadman principle. Another possibility would be the operation via hand or foot switch.

In the lifting function (13.1), compressed air flows through the conduit (28) and the bent pipe (6) into the upper region (22) of the plunger (4) and pressurizes the surface of the hydraulic fluid (27.1) with compressed air. At the same time, the hydraulic valve or valves (9) is opened between the plunger (4) and the cylinder tube (3), so that the hydraulic fluid (27) can flow into the interior spaces of the cylinder tubes (3) and extend the cylinder tubes (3) (17).

In the lowering function (13.2), the compressed air (26) flows out of the interiors of the plunger (4) and the hydraulic fluid (27) loses pressurization by the compressed air (26). When opening the hydraulic valve or valves (9), the hydraulic fluid (27) flows back into the interior of the plunger (4) and the cylinder tubes (3) enter (17). The hydraulic fluid (27) virtually always circulates in a closed circuit between the interiors of the plunger (4) and the interior of the cylinder tubes (3). When lowering (13.2), the air sounds at the actuation location, i. At the control point in the workshop, the discharge air can be led back into the installation cassette (1) via another line (14) and a silencer (29). This simultaneously causes a ventilation of the mounting cassette (1).

In another - not shown - execution the pressurized discharge air when lowering at least partially fed to a pneumatic pressure accumulator, which in turn can provide this stored compressed air at the next lifting operation available.

In yet another embodiment - also not shown - the pressurized discharge air can be at least partially made available to the compressed air generator as intake air so that it can not produce its compressed air generation with atmospheric air, but at least partially with biased, ie already pressurized air.

In the zero position (13.3) of the lever control (13) all paths are closed. The lift does not move.

Is a mechanical Absenksicherung (10) is installed when lowering (13.2) through the line (15) parallel to the pneumatic control of the hydraulic valves or (9) simultaneously the unlocking cylinder (16) of the lowering fuse (10) driven. The unlocking cylinder (16) has a compression spring (16.1), which wants to press the claw of Absenksicherung (10.1) in the Absetzrasten (10.2) of the Absetzstange (10.3). When lowering the Entriegelungszylinder (16) is pressurized, the compression spring (16.1) compressed and the claw of Absenksicherung (10.1) moves from the Absetzraste (10.2) of the Absetzstange (10.3). The lift can move down.

When lifting, the claw of the lowering safeguard (10.1) slides over the set-down pegs (10.2) of the settling rod (10.3) due to its geometric shape.

In Fig. 1 is the lowering safeguard (10) in the locked state, in Fig. 2 in unlocked condition and in Fig. 3 shown symbolically.

ADVANTAGES OF THE INVENTION

The advantages of this invention are that starting from the known state of the art a 2-ram lift is provided, which does not require its own electrical connection, which is also environmentally friendly, since it does not require oil as hydraulic fluid. It is operated with an environmentally friendly liquid, preferably with water. All the duties of testing and monitoring the installation cassette are eliminated.

All components of the lift, except for the lift control, are located inside the installation cassette. This means that there are no liquid-carrying pipe or hose lines outside the installation cassette. Another advantage is the small footprint of the lift, both the size of the mounting cassette, as well as the visible parts concerning.

Furthermore, the proven principle and advantages of the reversing cylinder are maintained. By coupling the two extending cylinder tubes at its lower end by means of a cross connection, both the rotation of the individual cylinder tubes about its longitudinal axis and the simple forced synchronization of both lifting units is ensured.

These benefits mentioned in the last paragraph were previously known only in conjunction with an electro-hydraulic drive and oil as a hydraulic fluid.

Another advantage is that the compressed air compressor present in each motor vehicle workshop is better utilized as a supply unit of the compressed air and no further drive unit is required.

Since the compressed air in the reservoir of the compressor can be stored, a lower electrical connection value is sufficient. The energy required for a lifting process is no longer available within the lifting time of the lift. This is particularly advantageous in areas that have only a single-phase power supply and lower voltages.

Another advantage is the ease of installation. The assembly personnel do not require any electrical knowledge and no electrical specialist is required for electrical commissioning.

Since no electrical energy is needed, this lift is very unsusceptible to interference. In the installation cassette is usually a high humidity, which can lead to disruption of electrical components over long periods. The pneumatic drive and control energy ensures high reliability and longevity.

The integration of a pneumatic pressure accumulator or the return of the pressurized discharge air to the pressure generator and the associated use of the pressurized discharge air for the next lifting process reduces the energy requirement of the lift.

LIST OF REFERENCE NUMBERS

1

installation cassette

2

guide

3

cylinder tube

4

plunger

5

crossbeam

6

bent pipe

6a

opening

7

connectivity

7a

opening

8th

connectivity

8 a

opening

9

hydraulic valve

10

mechanical lowering protection

10.1

Claw of the lowering safeguard

10.2

Absetzraste

10.3

Absetzstange

11

hydraulic line

12

hydraulic line

13

lever control

13.1

Lifting position

13.2

Position sinks

13.3

Zero position

14

management

15

management

16

unlocking cylinders

16.1

compression spring

17

Vertical direction of the upward and downward movement

18

lifting unit

19

Pages of the mounting cassette

20

Soil, sand, gravel, lean concrete

21

Sealing at the lower end of the cylinder tube

22

upper area of the plunger

23

upper opening of the pipe (6)

24

lower end plunger

25

lower end of cylinder tube

26

compressed air

27

hydraulic fluid

27.1

Surface of the hydraulic fluid

28

management

29

silencer

Claims (12)

1. Lifting platform for motor vehicles,

   - with two cylinder tubes (3) which move synchronously with one another in the vertical direction (17),

   - with a hydraulically operated lifting unit (18) for each cylinder tube (3),

   - with a mechanical transverse support (5) for the two lifting units (18) so as to ensure the synchronization of the two cylinder tubes (3) and to prevent them from rotating about their longitudinal axis,

   - with a mechanical anti-lowering means (10, 16) which prevents unintentional lowering in the event of a pressure loss,
   characterized in that each lifting unit (18) is equipped with a standing, hollow plunger piston (4) which is supported at the base, in the interior of which compressed air (26) and a hydraulic fluid (27) are located, the internal cavity of which is designed as a pressure vessel and to the lower end of which a curved tube (6) is fixed, said tube extending internally up to the upper region (22) of the plunger piston (4).
2. Lifting platform according to Claim 1, characterized in that the cavities of the two plunger pistons (4) store the necessary hydraulic fluid for extending the cylinder tubes.
3. Lifting platform according to Claim 1, characterized in that both plunger pistons (4) in each case have at the lower end of the plunger pistons (24) an opening (6a) for compressed air (26) and an opening (7a) for the hydraulic fluid (27), each of said openings having a connection possibility (7) (8) for a pipe or hose.
4. Lifting platform according to Claim 1, characterized in that the hydraulic fluid (27) is preferably water or an aqueous liquid or some other organic liquid, for example alcohol.
5. Lifting platform according to Claim 1, characterized in that between the openings (7a) of the plunger pistons (4) and the openings (8a) of the cylinder tubes (3) there is a pipe or hose connection (11, 12), between which at least one hydraulic valve (9) is arranged.
6. Lifting platform according to Claim 1, characterized in that the hydraulic fluid (27) flows between the cavities of the plunger pistons (4) and the cavities of the cylinder tubes (3).
7. Lifting platform according to Claim 1, characterized in that compressed air (26) flows through the curved tube (6).
8. Lifting platform according to Claim 1, characterized in that, during the lowering operation, the air flowing out is fed back into the installation bay (1) through the line (14) and the sound absorber (29).
9. Lifting platform according to Claim 1, characterized in that the pressurized discharged air is at least partially either fed to a pneumatic accumulator or made available to the pressure generator as pressurized intake air.
10. Lifting platform according to Claim 1, characterized in that a container is fitted at the end of the line (14) and after the sound absorber (29), in order to receive small amounts of hydraulic fluid.
11. Lifting platform according to Claim 1, characterized in that the surface of the hydraulic fluid (27.1) in the plunger pistons (4) in the retracted state reaches as far as close to the upper edge of the opening (6a) of the curved tube (6).
12. Lifting platform according to Claim 1, characterized in that the at least partially filled pneumatic pressure accumulator discharges at least some of its compressed air again during the next lifting operation.

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