CZ2003883A3 - Electric motor having a rotor rolling on a stator-rolling surface - Google Patents

Abstract

Disclosed is an electric motor having a rotor rolling on a stator-rolling surface wherein the electric motor converts feeding current pulses to magnetic rotary motion of the electric motor shaft (8). The stator (1) has on its circumference several magnetic circuits that are fed systematically with time-shifted current pulses and that stepwise attract the rotor (2) being freely and movably mounted in the electric motor radial direction. Inside diameter of the stator (1) differs from the rotor (2) outside diameter and therefore the rotor (2) eccentrically rolls on the stator (1) circumference and shifts relative thereto by each feeding current pulse by an exactly defined angle û a step. Connection of the electric motor rotor (2) and the shaft (8) is mediated through a swinging clutch (3). Stator teeth (4) are fixedly coupled with the stator (1) and rotor teeth (5) are fixedly coupled with the rotor (2) wherein they mutually form one internal spur gear system. Said internal spur gear system ensures parallelism of the stator longitudinal axis (24) and said rotor longitudinal axis (25), prevents slippage of the stator (1) relative to the rotor (2) and ensure constant angular shift û step of the electric motor shaft (8) in dependence on the feeding current pulse. Packing (13) of air gap extending between pole shoes (12) is attached to adjacent pole shoes (12).

Description

ELECTRIC MOTOR WITH ROTOR ROLLED ON THE STATOR ROLLING PLATE

Technical field.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor having a rotor rolled over a rolling surface of a stator used to convert feed current pulses into mechanical rotary motion, particularly in servo drives and positioning mechanisms.

BACKGROUND OF THE INVENTION.

At present, there are produced a wide range of different types of electric motors, differing in power supply (AC, DC, current pulses, etc.) as well as the nature of the operation (effects of the rotating magnetic field of the stator on the rotor winding) current, or force effect of the rotating magnetic field of the stator on the magnetic field of the rotor, etc.). The design of all these electric motors with a cylindrical shape of stator and rotor has common elements - the longitudinal axis of the stator and rotor is identical, the rotor is fixed on the shaft of the electric motor, which rotates in bearings and there is symmetrical air gap between stator and rotor.

Stepping motors are often used for positioning mechanisms and servo drives. They are electric motors of synchronous type, whose rotor is rotated with respect to the stator by each supply current pulse by a precisely defined angle - step, which is given by the design of the motor. The frequency of the supply current pulses is controllable and the rotor steps synchronously according to the supply current pulses up to the limit frequency. If the cut-off frequency is not exceeded, the stepper motor does not require a shaft position sensor. Thanks to this feature, stepper motors are used in robotics, computing, CNC machine construction and elsewhere. Compared to the use of other types of electric motors, they eliminate not only the position sensor of the electric motor, but also the speed sensor, often also the gearbox and the electronic control unit is simpler.

The disadvantage of stepper motors is the relatively low torques due to the weight, the use of high-quality permanent magnets is necessary to increase the torque. The rotor movement is accompanied by resonances and the limit acceleration must not be exceeded during operation.

2. Summary of the Invention.

The proposed electric motor according to the invention operates as an electric motor with a rotor rolled on a rolling surface of the stator for converting the supply current pulses to a mechanical rotary motion, in particular in actuators and positioning mechanisms. The rotor is rotated with respect to the stator by each supply current pulse by a precisely defined angle step, which is given by the design of the motor. The frequency of the supply current pulses is controllable and the rotor steps synchronously according to the supply current pulses.

The principle of the invention is that in the proposed electric motor, the longitudinal axis of the stator is parallel to the longitudinal axis of the rotor and is not identical therewith; the rotor is freely movable in a radial direction - it eccentrically rolls around the periphery of the stator, and while the electric motor is running, the longitudinal axis of the rotor creates a cylindrical surface whose diameter is the difference between the diameter of the rolling surface of the stator and the diameter of the rotor.

The connection of the rotor and the shaft of the electric motor is made by a swivel coupling; this swiveling clutch does not limit the rotor in its eccentric movement, but ensures the transmission of the torque of force from the rotor to the motor shaft without angular clearance.

During operation, the rotor continually touches the stator - the contact set of points is a segment of the common longitudinal length of the rotor and the stator, which by moving the rotor creates a cylindrical surface identical to the rolling surface of the stator.

The stator toothing is rigidly connected to the stator and the rotor toothing is rigidly connected to the rotor, forming at least one internal spur gear that ensures parallelism of the stator longitudinal axis and the longitudinal axis of the rotor.

The air gap filler between the pole pieces in the proposed electric motor is mounted on two adjacent pole pieces, the triangular cutouts of the filler being inserted into the edges of the pole pieces in the form of triangular projections. The filling is made of diamagnetic or paramagnetic material and mechanically machined so that the rolling surface of the stator is cylindrical and smooth.

The stator of the proposed electric motor is divided into a system of separate magnetic circuits - the electromagnet. The winding of each magnetic circuit is independently of the windings of the other magnetic circuits fed by current pulses from the control electronic unit. The winding current is not dependent on the electric motor load, therefore it is possible to adjust the current consumption according to the required torque and thus reduce the electric motor consumption.

The rotor of the proposed electric motor is made of ferromagnetic material, its rolling surface is cylindrical and smooth. The low weight of the rotor relative to the weight of the stator reduces the vibrations caused by the eccentric movement of the rotor.

-3 The advantage of the proposed electric motor over stepper motors is a high torque from the lowest rotor speed and high efficiency, the device has a smaller step length than stepper motors and does not use permanent magnets.

The operation of the electric motor according to the invention is based on the attractive force effects of the stator magnetic field on the rotor. The stator is divided into n separate magnetic circuits. Each magnetic circuit is formed by at least one winding placed on at least one pole of the stator, to improve the magnetic and mechanical properties, it is possible to connect at least two adjacent windings on at least two adjacent poles. This creates areas of action of the individual magnetic circuits on the stator. Passing the first supply current pulse through the winding of the first magnetic circuit produces a magnetic flux, passing the magnetic flux through the air gap between the stator and the rotor generates a magnetic attraction force. The rotor pulls to the stator and is fixed in this position for the duration of the first supply current pulse. The second supply current pulse flowing through the winding of the second magnetic circuit causes the rotor to be attracted to the stator in the region of application of the second magnetic circuit and is fixed in this position for the duration of the second supply current pulse. The third supply current pulse to the winding of the third magnetic circuit causes the rotor to be pulled to the stator in the region of the third magnetic circuit and is fixed in this position for the duration of the third supply current pulse etc. The stator has n magnetic circuits around the circumference supplied by time-shifted current pulses. These cause the rotor to be gradually tightened to the periphery of the stator, the rotor is gradually rolled along the stator. Because the stator rolling circuit is different from the rotor rolling circuit, each power current pulse into the winding of the next magnetic circuit causes the rotor to rotate with a precise angle-step relative to the stator. The magnitude of the angular displacement - step is proportional to the difference between the stator rolling diameter and the rotating rotor diameter and inversely proportional to the number of stator magnetic circuits. The torque is transmitted from the rotor, which performs eccentric movement, to the shaft of the electric motor by means of a swivel coupling, for example a double cross joint, bellows or the like. The stator toothing is fixedly connected to the stator. This spur gear ensures parallelism between the stator and rotor longitudinal axes, prevents the stator and rotor from rotating together, and ensures a constant angular displacement - step of the electric motor shaft depending on the current supply pulse.

-4Overview of figures in the drawing.

The invention will be illustrated in more detail in the figures below:

FIG. 1 shows a stator-rotor configuration, wherein the internal diameter of the rotor is greater than the outer diameter of the stator, and therefore the rotor is rolled along the outer periphery of the stator; therefore, the rotor is rolled on the inner stator circuit fig.3 example of one stator magnetic circuit fig.4 time course of supply current pulses, which supply the winding n of stator magnetic circuits fig.5 a exploded view of possible components of the electric motor in which the rotor is rolled on the inner circuit Fig. 6 a section of an electric motor in which the rotor is rolled along the inner periphery of the stator (along the stator rolling surface) Fig. 7 a section of an electric motor in which the rotor is rolled along the outer periphery of the stator (along the stator rolling surface) .8 detail of filler between pole Fig. 9 block diagram of the electric motor control unit

Examples.

The basic parts of the electric motor are stator 1 and rotor 2. Assuming parallelism of the longitudinal axis of the stator 24 and the longitudinal axis of the rotor 25, these parts can assume two usable positions with each other.

-5Example 1

The electric motor constructed in FIG. 1 such that the inner diameter of the rotor 2 is greater than the outer diameter of the stator 1 and therefore the rotor 2 is rolled along the outer periphery of the stator 1- The rolling surface 26 of the stator 1 is a cylindrical surface. the diameter of the stator 1, the rolling surface 27 of the rotor 2 is a cylindrical surface with a diameter equal to the internal diameter of the rotor 2. Fig. 7 is a cross-sectional view of an electric motor according to this example. The auxiliary shaft 14 is rigidly connected to the rear flange 7 and the stator 1. A stator toothing 4 is fixed to the support 23, which is coupled to the auxiliary shaft 14, and the rear flange 7, and the rotor 2 is firmly connected to the swivel coupling 3. The other side of the swivel coupling 3 is mounted on a front flange 5, which rotates freely in bearings 11 mounted on an auxiliary shaft 14. On the front flange 5 is mounted a shaft of an electric motor 8 to which the torque of the rotor 2 is transmitted via the swivel coupling 3 and the front flange 5. The rotor 2 is fixedly connected to the rotor toothing 5, which, upon eccentric movement of the rotor 2, rolls on the stator toothing 4. Both toothings form an internal spur gear which ensures parallelism of the longitudinal axis of the stator 24 and the longitudinal axis of the rotor 25.

Example 2

The electric motor constructed in FIG. 2 such that the inner diameter of the stator 1 has a greater value than the outer diameter of the rotor 2 and therefore the rotor 2 is rolled inside the stator 1. The rolling surface 26 of the stator 1 is a cylindrical surface. The rolling surface 27 of the rotor 2 is a cylindrical surface with a diameter equal to the outer diameter of the rotor 2. FIG. The shaft of the electric motor 8 is mounted in bearings 11 and is rigidly connected to the swiveling clutch 3. This swiveling clutch 3 is fixed at its other end to the rotor 2 and transmits the rotational movement of the rotor 2 to the shaft of the electric motor 8 while compensating for its eccentric movement. The stator toothing 4 is fixedly connected to the front flange 6, the rear flange 7 and hence the stator I, in which, when the rotor 2 is eccentrically moved, the rotor toothing 5, which is fixed to the rotor 2, rolls. the parallel position of the longitudinal axis of the stator 24 and the longitudinal axis of the rotor 25.

An exploded device according to this example is shown in Fig. 5 and consists of the following main parts: stator 1, rotor 2, swiveling couplings 3, stator teeth 4, rotor teeth 5, front flanges 6, rear flanges 7, electric motor shafts 8.

Design of the magnetic circuits of the stator, timing of the supply current pulses, air gap fill between two adjacent pole pieces and block

The diagram is similar for both designs of the electric motor, so it is described only in Example 2 as follows:

FIG. 3 shows an example of one magnetic circuit of a stator 1. It consists of two adjacent poles 9 of a stator 1 made of ferromagnetic material and two windings 10. On each pole 9 there is one winding 10. The connection of two windings 10 at two adjacent poles 9 results in one magnetic circuit. Passing electric current through the winding input terminal 219 of the winding output terminal 22 produces a magnetic flux.

Fig. 4 shows the time course of the supply current pulses that supply the electric motor. The stator 1 contains n magnetic circuits. In order to roll the rotor 2 over the entire circumference of the stator 1, n time-shifting current pulses, which are switched sequentially into the windings 10 of the individual magnetic circuits, are required.

FIG. 8 shows a detail of the air gap filler 13 between two adjacent pole pieces 12. This filler 13 of diamagnetic or paramagnetic material is attached to both adjacent pole pieces 12 by inserting the filler 13 with triangular side cutouts 15 into the edges of the triangular side extensions 12. This insertion is provided in the direction of the longitudinal axis of the gap of the adjacent pole pieces 12. The purpose of the filler 13 is to provide a smooth cylindrical rolling surface 26 of the stator 1.

Fig. 9 shows a block diagram of a control electronics unit 28 that powers and controls an electric motor 20. The input circuit 17 converts input information to control commands (start, stop, rotation + -, pulse width, number of pulses, current limitation) controlling the pulse generator. 18, which generates supply current time-shifted pulses for π of the output power members, which feeds the current impulses of the windings n of the magnetic circuits of the electric motor 20. The start command controls the start of the electric motor 20, stop command controls the electric motor stop 20; 8, the pulse width command controls the rotational speed of the motor shaft 8 of the electric motor 20, the command number of pulses determines the number of steps of the motor shaft 8, the current restriction command controls the consumption of the electric motor 20.

Claims (5)

Patent claims. An electric motor having a rotor (2) rolled over a rolling surface (26) of a stator (1) for converting supply current impulses into mechanical rotary motion, in particular in actuators and positioning mechanisms, characterized in that the longitudinal axis of the rotor (25) is parallel to but not identical with the longitudinal axis of the stator (24). Electric motor with a rotor (2) rolled over a rolling surface (26) of the stator (1) according to claim 1, characterized in that the rotor (2) is mounted freely movable in the radial direction of the electric motor. Electric motor with a rotor (2) rolled over a rolling surface (26) of the stator (1) according to claims 1 and 2, characterized in that the connection of the rotor (2) and the shaft of the electric motor (8) is made by a swiveling clutch (3). Electric motor with a rotor (2) rolled over a rolling surface (26) of a stator (1) according to claims 1 to 3, characterized in that the stator toothing (4) is fixedly connected to the stator (1) and the rotor toothing (Sj-is). - fixedly connected to the rotor (2), forming at least one internal spur gear with one another. An electric motor with a rotor (2) rolled over a rolling surface (26) of a stator (1) according to claims 1 to 4, characterized in that the rolling surface (26) of the stator (1) is formed by the end faces of the pole pieces (12) and fillings. (13) mounted on two adjacent pole pieces (12), the triangular cutouts (15) of the filler (13) being inserted into the edges of the pole pieces (12) in the form of triangular projections (16).