DE29806756U1 - Positioning system for lifts and similar devices - Google Patents

Description

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Positioning system for elevators and similar devices Description

Task

The invention is based on the task of determining the position of an elevator in relation to a building or the stops as accurately as possible using a reliable and cost-effective device.

An important subsystem in elevator systems is the device used to determine the position of the elevator car in the shaft. There are a large number of known designs for this. Recent developments in the semiconductor market have made inexpensive and high-resolution systems possible.

Solution approach

The task is solved by exciting a standing wave between a microwave transmitter and a microwave mirror and measuring this with two microwave receivers that are offset by a certain distance. The transmitter, receiver and mirror are mounted in a suitable manner on the building or on the elevator car. An evaluation electronics determines the position of the elevator car in the shaft from the received signals.

Advantages

The advantage of this arrangement is that it is very cost-effective to implement, that it is virtually unaffected by dirt or temperature, that the measurement resolution is very high and - with certain restrictions - the location can be determined absolutely at any time.

details

Shaft positioning systems for elevator systems have to fulfill various tasks: On the one hand, they must provide the control system with all the information required for precise entry and adjustment to the stop, on the other hand, these systems must also fulfill safety-related tasks and ensure that no dangerous conditions occur, such as travel movements or door movements outside the stop.

For cost reasons, incremental systems are generally preferred today, which means that when the system is switched on again, the control system must first determine the absolute position in a learning run.

Conventional systems work with bistable or monostable magnetic switches or magnetic sensors that scan movable or fixed magnets. Other systems use slot or proximity switches and movable or fixed markers.

More modern variants sensor the speed limiter's pulley or convert the linear movement of the elevator car into the rotary movement of a multi-turn resolver or an incremental encoder. Acoustic methods are also known, for example measuring the travel time of sound waves in special wires.

What all modern processes have in common is that, unlike with traditional processes, it is no longer necessary to laboriously adjust marks in the shaft. The effort required to commission and adjust elevator systems is a decisive factor in the cost structure.

The subject of this invention is a system that has some significant advantages over all known systems:

• The system is maintenance-free and wear-free.

• Temperature differences do not affect the system.

• Contamination with construction dust has no noticeable effect on the system.

• The relative measurement resolution is in the range of one millimeter.

• A large number of measurements can be carried out per unit of time.

• The system delivers not only the high-resolution relative position, but also a rough statement about the absolute position of the car and information about the magnitude of the measurement error.

• The system is very easy to install.

• The costs for the system do not depend on the shaft length.

• It is not necessary to transmit signals from this system via the hanging cable.

• The system can be encapsulated with non-metallic materials.

• The system does not affect the appearance and aesthetics of the facility.

The working principle itself is not new: A standing wave is excited between a microwave transmitter and a mirror. If these two elements are mounted on the elevator car on the one hand and on the building or shaft frame on the other, then wave nodes and antinodes alternate near the transmitter depending on the distance. With two microwave receivers arranged out of phase, the change in the

Distance can be recorded with the correct sign: If you imagine the two receiver signals as components of a vector in a Cartesian coordinate system, the vector describes a circular path as the elevator car moves - or more precisely, a spiral path. The direction of rotation of the vector corresponds to the direction of movement. The diameter of the path is a rough measure of the absolute distance.

The evaluation of the two receiver signals is preferably carried out digitally and with a signal processor - but other evaluation devices are also conceivable.

Today, elevator controls almost always work with microcomputers. This provides a standardized interface between the sensor system and the control computer.

It makes sense for the positioning system to provide the phase angle, the signal amplitude and a measure of the signal quality. The evaluation will be carried out differently in each control computer of the many brands available on the market.

Design variants concern beam bundling and mounting alternatives.

Claims (1)

* » * '&Lgr; * •••J « ft·» · Φ Protection claims (1) Electronic sensor system for determining the position of elevators and similar objects, characterized in that a microwave transmitter and a microwave mirror are mounted on the one hand on the elevator car and on the other hand in a fixed location, for example on the building or on the shaft frame, and the standing wave that forms is detected by at least two microwave receivers that are installed out of phase and location information is determined from this in an evaluation electronics. (2) Electronic sensor system according to claim (1), characterized in that the transmitter and receiver are mounted on the elevator car and the microwave mirror is mounted on the building or shaft frame. (3) Electronic sensor system according to claim (1), characterized in that the transmitter and receiver are mounted on the building or shaft frame and the microwave mirror is mounted on the elevator car. (4) Electronic sensor system according to claim (1), characterized in that the microwave reflector is designed as a cube corner or triple mirror. (5) Electronic sensor system according to claim (1), characterized in that the microwave reflector is designed as a plane mirror. (6) Electronic sensor system according to claim (1), characterized in that the microwave reflector is made of a combination of microwave lens and mirror. (7) Electronic sensor system according to claim (1), characterized in that the microwave transmitter focuses the microwave beam with a concave mirror. (8) Electronic sensor system according to claim (1), characterized in that the microwave transmitter focuses the microwave beam with a microwave lens. (9) Electronic sensor system according to claim (1), characterized in that the evaluation device evaluates not only the phase of the standing wave, but also its amplitude and derives therefrom a measure of the absolute position.