RU2410820C2 - Electric motor with low rpm, in particular for actuation of lifting devices - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention refers to the field of electric engineering, in particular, to electric machines, and relates to features of design of electric motors with low rpm. Electric motor (10) is proposed with low rpm, comprising rotor (17), with supply from source of three-phase AC voltage, magnets (21, 22) and stator coil (24). Rotor (17), stator (24) and magnets (21, 22) are located in body (13) of pulley, which rotates around fixed axis (11), besides, rotor (17) is fixed to body (13), coil of stator (24) is arranged with supply from DC voltage source. Magnets (21, 22), forming stator (24), are fixed to axis (11) and are arranged with the possibility to locate a stator (24) coil in them, and body (13) of pulley is fixed to two diamagnetic side plates (16, 16'). Motor comprises electromagnet brake (25), including two metal disks, one of which is arranged as a whole with one of specified diamagnetic plates (16'), and the other one with magnet (22), which forms poles of stator (24), and spring pushes of disks arranged in according slots of magnet (22). To resist action of lowering braking disk, there is a thrust bearing. Besides, the possibility to control frequency of rotor voltage is provided to produce required motor rpm.

EFFECT: production of perfect working characteristics of motor with low rpm, having compact design, which does not require step-down gear.

7 cl, 1 dwg

Description

Technical field

The present invention relates to a low speed electric motor. In particular, the present invention relates to a low speed electric motor, which is preferably used where high torque is required.

For example, the proposed electric motor can be used to actuate lifting devices, such as elevators.

State of the art

Electric motors used where significant torque is needed, for example for lifting elevators, are usually installed in conditions of insufficient space, and this causes great difficulties, since the engine is equipped with a reduction gear and a pulley on which cables are hoisted to raise and lower the cab The elevator turns out to be quite cumbersome.

The reduction gears used in these areas often have time-varying electromechanical characteristics, which leads to instability during operation and a significant deterioration in engine performance.

Description of the invention

The problems of the known devices are solved in the present invention due to the creation of a compact engine of a new design, which does not require a downshift.

In particular, for elevators, the present invention provides an electric motor with a low number of revolutions (for example, approximately 50 rpm, which corresponds to a lifting speed of approximately 1 m / s), using which the components necessary for moving and braking the car can be located directly inside the drive pulley.

The features of such an electric motor are described in the main claim. The dependent claims describe particular preferred embodiments of the proposed motor.

In the most typical configuration, the proposed motor contains a multi-pole rotor powered by a three-phase AC voltage source and a stator, which has the same number of magnetic poles as the rotor, and which is made in the form of a coil powered by a DC source.

According to a most preferred embodiment of the invention, the direct voltage is obtained from a single-phase rectified, and therefore pulsating, alternating voltage. Constant voltage provides excellent engine performance.

Description of drawings

Other features and advantages of the invention will become apparent from the description of certain embodiments thereof, which are non-limiting examples. The description is given using the attached drawing, in which the proposed motor is presented in section.

Description of some embodiments of the invention

The entire proposed electric motor with a low number of revolutions, used to actuate the lifting devices, is indicated in the drawing 10.

The motor 10 is mounted on bearings 12, 12 '(roller or ball) on a fixed metal axis 11 and is enclosed in a pulley housing 13, on the outer surface of which there are a number of grooves 14, 14', ... designed to accommodate cables (not shown) for driving into the operation of a lifting device, such as an elevator. The housing 13 is fixedly fastened by screws 15 to two diamagnetic side plates 16, 16 ', which are connected to bearings 12, 12'.

In fact, the electric motor is placed in the cavity formed by the plates 16, 16 'and the housing 13.

On the inner surface of the pulley 13 there is a rotary package 17 made with it in one piece with a number of grooves (not shown), which are designed to accommodate a three-phase winding powered by an AC voltage source. The specified three-phase winding is connected to three corresponding conductive rings 18, 18 ', 18 ", which are inserted into the corresponding grooves cut in the plate 16'. A shield 19 of two parts joined together is attached to the axis, which holds three brushes 20, 20 ', 20 "in contact with the respective rings 18, 18 ', 18."

Also attached to the axis 11 are magnets 21, 22 located next to each other, and limiting the cavity in which the stator coil 24 is located, powered by a constant voltage source to create magnetic polarities of the stator.

The engine 10 contains an electromagnetic brake 25, containing two metal disks, one of which is made in one piece with the plate 16 ', and the other with the magnet 22, and spring pushers of the disks placed in the corresponding grooves of the magnet 22.

Thus, all the necessary equipment for moving and braking can be contained in the drive pulley, therefore, such an engine is particularly suitable for use as a full drive without downshift.

According to the invention, the power supplies of the coil 24 (a constant voltage source obtained by rectifying a single-phase alternating voltage) and windings 17 (a three-phase alternating voltage source) are regulated by a suitable control device to obtain the required speed, and the speed of the motor depends on the number of its poles and the frequency of the three-phase power source.

For these purposes, a frequency control device can be used, for example an AC-DC-AC or DC-AC converter.

According to the invention, the coil 24 is powered from a constant voltage source. In this embodiment, the engine contains a large number of magnetic poles, as many as the rotor, and the poles in the stator are bifurcated, as in automobile alternators. In this case, some characteristics characteristic of a synchronous motor are lost, but an acceleration torque appears, which makes it possible to obtain the required speed by simply changing the frequency of the three-phase rotor supply.

To prevent current leakage between the shaft and the coil, the plates 16, 16 'are made of diamagnetic material.

Since the engine has three modes (constant speed, braking and acceleration), the stator 24 is constantly powered from a constant voltage source, and the rotor 17 is supplied from an alternating voltage source controlled by a frequency converter that is external to the rotor. In this case, in the acceleration and deceleration modes, the frequency of the three-phase voltage of the rotor 17 is regulated using frequency converters ("alternating-direct-alternating current" or "direct-alternating current"), which provide the required frequencies, currents and, therefore, torques.

In the foregoing text, the invention is described using an example of a preferred embodiment in which the main axis is stationary, the stator is integral with the shaft, and the rotor rotates around the shaft and stator.

However, there are possible implementations in which the functions of the engine parts are inverse to those described: the main axis rotates, and the motor housing, made in one piece with a three-phase winding, is stationary.

In this case, the main axis is equipped with two conductive rings that are connected to the corresponding cables, inserted into the grooves of the shaft and connected to the windings of the coil and rotating magnets.

To transfer current, two brushes are connected to these rings, and mechanical drive means, in particular lifting means, are connected to the main axis.

Claims (7)

1. An electric motor (10) with a low number of revolutions, comprising a rotor (17) powered by a three-phase (18, 19, 20) AC voltage source, ferrous magnets (21, 22) and a coil that forms a stator (24), and an electromagnetic brake (25), the rotor (17) and the stator (24) having the same number of magnetic poles,
a rotor (17), a stator (24) and magnets (21, 22) are placed in a pulley case (13), which rotates around a fixed axis (11), and the rotor (17) is attached to the case (13);
the stator coil (24) is powered by a constant voltage source, while it is possible to control the frequency of the rotor voltage (17);
the magnets (21, 22) forming the stator (24) are fixedly attached to the axis (11) and are configured to accommodate the stator coils (24),
moreover, the pulley body (13) is fixedly attached to two diamagnetic side plates (16, 16 '),
the electromagnetic brake (25) contains two metal disks, one of which is made in one piece with one of these diamagnetic plates (16 '), and the other with a magnet (22), which forms the stator poles (24), and spring pushers of the disks, placed in the corresponding grooves of the magnet (22). 2. An electric motor according to claim 1, wherein said diamagnetic side plates (16, 16) are connected to two roller bearings (12, 12 ') interacting with said axis (11). 3. The electric motor according to claim 1, characterized in that it further comprises a fixed shield (19), on which there are brushes (20, 20 ', 20 ") connected to the respective rings (18, 18', 18"), rotating together with a pulley housing and electrically connected to a three-phase rotor winding. 4. The electric motor according to claim 1, characterized in that on the pulley housing (13) there are peripheral grooves (14) for accommodating the drive cables. 5. The electric motor according to claim 1, characterized in that there is additionally a mechanical brake (25) inside it. 6. The electric motor according to any one of claim 1, characterized in that the rotor and stator are made in one piece with the means of transmission of motion. 7. The electric motor according to claim 6, characterized in that the means of transmission of motion contain gear and friction gears.