Wittur Ag

Bucher Guyer Ag

Wittur Gmbh

Sead Veletovac

Luigi Del Re

Daniel Moser

Richard Von Holzen

Roland Bisig

Andreas Schrempf

Hubert Haussler

A control valve unit for a hydraulic elevator includes two control valves wherein the flow of hydraulic oil from a tank to a lifting cylinder driving an elevator cabin and/or from the lifting cylinder to the tank can be controlled. In case of an upward movement of the elevator cabin, hydraulic oil is conveyed by a pump driven by an electromotor from the tank through the control valve unit to the lifting cylinder. In the case of a downward movement of the elevator cabin, the hydraulic oil flows through the control valve unit to the tank without the pump working. The control of the upward movement and the downward movement of the elevator cabin is achieved by one single pilotable control valve, respectively, that are provided to act as a check valve as well as a proportional valve.

Valve control unit for a hydraulic elevator

A method for controlling a hydraulic elevator whose car can be displaced by a hydraulic drive mechanism by hydraulic oil fed through a cylinder line or evacuated from said hydraulic drive mechanism by a pump that cooperates with a first control valve unit and a second control valve unit, wherein the flow the hydraulic oil is controlled by a measuring device and operation of the elevator can be controlled and regulated by a control apparatus. The load of the elevator car is determined by a load pressure sensor detecting pressure P in the cylinder line and is controlled preferably in a constant manner by changing the control of the second control valve unit in such a way that movement of the elevator car can be controlled in a very precise manner. When the elevator car is descending, the dropping pressure P in the cylinder line is regulated by changing the first control valve unit in such a way that the descending movement of the elevator-cabin can also be controlled in a very precise manner.

Control method and apparatus for a hydraulic elevator using only load pressure data

The hydraulic or pneumatic drive for lifting and lowering loads, in particular for lifts, has a working cylinder ( ) forming a pressure chamber ( ) connected to a pressure fluid source ( ) and subjected to a pressure fluid. It also has a lifting piston ( ) tightly guided in the working cylinder and a guide rod ( ) arranged in the working cylinder. The guide rod ( ) projects into the interior of the lifting piston ( ) which tightly encloses the guide rod ( ). The end ( ) of the lifting piston ( ) which projects into the pressure chamber ( ) forms an annular face ( ) which is subjected to pressure fluid. The interior of the lifting piston ( ) forms an additional pressure chamber ( ) subjected to pressure fluid and which is connected to its own pressure fluid source ( ). The pressure fluid source connected to the working cylinder ( ) delivers pressure fluid at a substantially constant pressure, whereas the pressure fluid source ( ) connected to the additional pressure chamber ( ) delivers pressure fluid at a variable pressure. The additional pressure chamber ( ), subjected to pressure fluid, subdivides the total force needed to lift a load into two partial forces, one of which acts upon the annular face and the other in the interior of the lifting piston, close under the load. In this way, the partial force acting upon the entire length of the lifting piston and subjecting the piston to buckling is substantially reduced. It is thus possible to reduce the amount of material required without affecting buckling resistance.

Hydrostatic displacement drive for lifting and lowering and holding loads, in particular for lifts

Method and device for controlling a hydraulic lift

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Dübendorf, Switzerland

Sead Veletovac