JPS6231689A - Method of controlling speed of business of escalator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to low speed driving of escalators for maintenance and inspection purposes.

It is known to drive escalators at low "service" speeds for inspection and maintenance purposes. In one arrangement, the stator of the drive motor has two windings, one used for normal full speed operation and one used for service speed. Such schemes require large start-up currents and large idle currents, and the overall efficiency is less than desirable. Another arrangement uses a small auxiliary motor to drive the escalator at low speeds. This arrangement requires expensive mechanical installation and has deficiencies that require additional maintenance.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a simple and inexpensive device for driving escalators at low speeds.

According to the invention, a service unit consisting of a rectifier and a variable frequency/variable voltage inverter (combined termed converter) is inserted between the alternating current source and the escalator motor. The voltage and frequency output of the inverter is set so that the escalator motor is operated at low speed.

Other objects, features and advantages of the invention will become apparent from the following description based on the accompanying drawings.

Variable voltage and variable frequency inverters to control motor speed are readily available. One example is the Lenze™ 75o IJ-x, gate turn off (GTO) type inverter, commercially available from Lenze GmbH & Co., Hans Lenz Strasse 1, Anilzen 2, Federal Republic of Germany.

The drawing shows a business unit 10 of the invention connected in the power line of an aperiodic S-force rake motor 12. During normal operation, an alternating current source 14 supplies power to the motor 12 through line 16. (Only one of the three-phase power lines is shown for clarity.) Connectors 18 and 20 are mounted in line 16.

The connector 18 is of the disconnecting (normally closed) type, and when the corresponding plugs 22 and 24 are inserted (shown in dashed lines), the direct connection between the AC source and the motor is replaced by a connection through the service unit 7, and the motor All power to flows through the business unit.

In the service unit, a rectifier 26 first converts alternating current from the source into direct current, and then an inverter 28 converts this direct current back into alternating current and supplies it to the motor. An inverter, such as the Renzuf 56 described above, incorporates a control circuit 30 that varies the frequency and voltage of the inverter output according to the setting of a set point potentiometer 32 through the use of pulse width modulation. The variable frequency and variable voltage output of the service unit affects the motor speed accordingly. A combination of a rectifier and an inverter as shown in the figure is called a converter.

To operate the electric motor at low speed when servicing the escalator, the repair tool must be preset (adjusted at the factory).
Or simply plug in the adjustable business units in the field.

The advantages of business units as described above are numerous.

The operating speed can be adjusted to any value from about 5% to 100% of the rated motor speed. Starting current is small. To retrofit an existing escalator, all you need to do is install the appropriate connectors (and disconnect the existing service speed equipment).No mechanical parts are involved, perhaps the greatest of all advantages being that Only one service unit is required at a time to service an escalator, for example one service unit for one underground scissor.

It should be understood that various modifications may be made to the invention without departing from its scope.

[Brief explanation of the drawing]

The accompanying drawings are schematic block diagrams of the present invention. 10... Business unit, 12... S-force lake electric motor, 14... AC source, 16... Power line, 18.20
...Connector, 22/24...Plug, 26...
Rectifier, 28 Inverter, 30... Control circuit, 32.
...Set value potentiometer. Engraving of the drawings (no change in content) Procedural amendment (method) 1936 Year Month Date Commissioner of the Patent Office Black 1) Mr. Akihiro ml, Indication of case 1985 Patent Application No. 123186 2, Title of invention Escalator service speed control Method 3: Relationship with the person making the amendment Applicant name Otis Elevator Company 4, Agent

Claims (2)

[Claims] (1) A method for providing a low operating speed to an escalator having an AC drive motor; connecting an external variable frequency/variable voltage power converter to the drive motor; adjusting the frequency and voltage of the converter to achieve the low operating speed; A method characterized by giving speed. (2) A method of modifying an escalator having an AC drive motor connected to an AC source via a line to provide the low operating speed; providing a connector within the line; and providing the line with a connector. connecting an external variable frequency/variable voltage power converter to the converter, replacing the direct connection between the drive motor and the alternating current source via the line with a connection between the drive motor and the alternating current source via the power converter; A method characterized in that frequency and voltage are adjusted to provide said lower operating speed.