GB2025705A

GB2025705A - Synchronous drive motor

Info

Publication number: GB2025705A
Application number: GB7923291A
Authority: GB
Original assignee: SCHLEICHER RELAIS; Schleicher GmbH and Co Relais Werke KG
Current assignee: SCHLEICHER RELAIS; Schleicher GmbH and Co Relais Werke KG
Priority date: 1978-07-05
Filing date: 1979-07-04
Publication date: 1980-01-23
Also published as: DE2829944A1; IT1114749B; JPS5510891A; FR2430685A1; CH639802A5; IT7948461A0

Abstract

A drive motor, in particular a miniature synchronous motor, in combination with a relay-type movable armature 13', the movable armature being actuated by the flux produced by the excitation winding of the motor. The motor stator comprises two magnetically conducting stator laminations 1', 5' having stamped out interdipitaled poles 1.1' and 5.1'. The pivoted armature 13' may operate a switch. <IMAGE>

Description

SPECIFICATION Synchronous drive motor The invention relates to a drive motor, in particular a synchronous motor, which also comprises a movable element and means for generating a magnetic field to move the movable element to shunt a region of increased magnetic resistance in the magnetic flux path of the magnetic field generating means.

Drive motors, in particular miniature synchronous motors, which in addition to their rotary function, i.e.

a rotating output shaft, also have a second function, for example a connecting function when using a sliding rotor, are generally known. Thus, for example, a miniature synchronous motor with a sliding rotor is described in German Auslegesschrift 1172 354. This comprises a rotary hysteresis motor having a stator which consists of ferromagnetic claw-pole laminations located on both sides of a stator winding and an axially extending ferromagnetic tubular connecting part magnetically interconnecting with claw-pole laminations. A ferromagnetic armature is provided which is able to move together with the sliding rotor and is attracted magnetically by the magnetic field of the stator in the direction of the starting movement of the sliding rotor, in the path of its substantially ferromagnetically closed magnetic flux.In addition to the main air gap existing between its pole lamination teeth, the stator comprises an auxiliary air gap, whereby during the passage of the sliding rotor into its operating position, the armature is drawn into the magnetic force field of the auxiliary air gap and magnetically closes the latter at least partially. The coil of the synchronous motor thus simultaneously takes over the function of an excitation coil of a coupling magnet and in particular as a result of the translatory motion of the rotor moving in the direction of the axis of rotation.

For many electromechanical appliances, in particular switching devices such as time-lag relays, automatic staircases lighting switches and the like, which require the rotary motion drive of the motor as a timing element and in addition the drive of an electromagnet for effecting a coupling and/or a switching function required, sliding armature motors have been used despite their extraordinarily low efficiency. This is because the elimination even of only one component, in particular when the latter is a coil, can provide a considerable advantage as regards assembly and price with respect to other constructions in the case of mass produced products of the type in question.

A further known hysteresis motor, in which a permanent magnet armature is not used for the rotor part, serves as a miniature synchronous motor with a moving armature for the operation of time-lag relay gearing (German Patent Specification 1 613 604). In this synchronous motor, a coupling wheel is actuated by the moving armature, the latter being an outer rotor with a stator of the claw-pole design with an annular excitation coil. An annular auxiliary air gap is arranged concentricaily with respect to the axis of the motor between the pole laminations at one end face of the stator and the armature is guided axially by two diametrically opposed supports attached to the pole laminations and bearing continuously against the pole laminations in the region of one support and forming the point of rotation at the bearing point.As aforementioned, hysteresis motors have an extraordinary low degree of efficiency, which is of the order of 0.3%, and the hinged armature arranged at right-angles to the rotor shaft, through which armature the shaft is guided, is at the maximum thus only able to undertake coupling functions, i.e. to bring a pinion into mesh with another by translatory movement. The reliable closure of contacts, which has to be repeated millions of times during continuous operation, is not ensured with an arrangement of this type.

Finally, reference should also be made to a drive motor, in particular a synchronous motor of the aforementioned type described in German Offenlegungsschrift 2 004 663, which is likewise constructed as a magnetic sliding armature motor and in which the translatory motion of the rotor shaft against the action of a spring force is likewise suitable for undertaking coupling functions. This known drive motor, which may have a relatively small construction, cannot be subjected to high requirements.

However, it may be used in a particularly advantageous manner for programme control devices, in particular in household washing machines, for disengaging or engaging programme-transmitting parts.

Based on this prior art, an object of the present invention is to improve and develop the basic idea of dispensing with a coil in an electromagnetic appliance, which must have both a drive motor for providing a rotary motion and an excitation coil for achieving a translatory motion, to provide a small construction having a low number of parts and improved efficiency in which the translatory motion is used not only for coupling operations, but also for switching operations.

According to the present invention there is provided a drive motor comprising a synchronous motor, a movable element, and means for generating a magnetic field to move the movable element to shunt a region of increased magnetic resistance in the magnetic flux path of the magnetic field generating means, characterised in that the magnetic field generating means comprises an excitation winding and a pole core arranged to actuate the movable element and to simultaneously predetermine the magnetic field for the operation of the motor, the motor stator comprising two magnetically nonconducting and interconnected stator laminations which define a closed magnetic circuit with the pole core and the movable element when the movable element is actuated.

Preferabiy the magnetic circuit flux for the motor and the movable element passes via two air gaps located in series with regard to the magnetic flux, one air gap being located between stator poles defined by the laminations and a permanent magnet rotor of the synchronous motor, and the other gap being located between the movable element and the pole core.

Alternatively, the air gaps between stator poles defined by the laminations and a permanent magnet rotor of the motor and between the movable element and the pole core are parallel to each other in the magnetic circuit.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a first embodiment of the invention in plan view; Figure2 is a cross section of the embodiment of Figure 1 in side view; Figure 3 shows a perspective exploded view to illustrate the individual parts of the embodiment according to Figures 1 and 2; Figure 4 is a plan view of a further advantageous embodiment of the invention; and Figure 5 is a cross section of the embodiment according to Figure 4.

The invention makes it possible to disperse with the coil winding which was hitherto absolutely necessary in synchronous motors by providing a magnetic circuit incorporating for example the excitation coil of a hinged armature magnet. This makes it possible to reduce manufacturing costs and at the same time obtain a considerable saving of space. In addition a reduced input power may be used, despite high driving requirements and high requirements relating to switching functions. The essential drawback of hysteresis motors, namely their extraordinarily low degree of efficiency of the order of 0.3%, is avoided, since permanent armature motors may be used having known efficiencies of approximately 10%.It is also possible to avoid the usual drawbacks of sliding armature motors, i.e. the motor thrust is dependent on installation position and the motor is ill-suited for carrying out switching functions, as a resultofthetranslatory motion of the rotor shaft due to the low pressing force of the sets of contacts to be connected therewith.

Referring in particular to Figures 1 to 3 of the accompanying drawings, a miniature synchronous motor in combination with a hinged armature magnet is illustrated. The miniature synchronous motor is in this case used for a time-lag relay having contacts which can be actuated immediately and contacts which can be actuated after a delay e.g.

time-lag contacts, in combination with a movable armature having an associated armature coil. The motor comprises two stator laminations 1 and 5 from which individual poles 1.1 and 5.1 are bent. In the assembled state, these poles define claw-poles directed towards each other and arranged on a circle concentric with respect to the axis of rotation of the motor rotor.

The stator lamination 1 has a projection extending on one side beyond the region of the synchronous motor. This projection supports a flap bent at right-angles to the lamination 1 and provided with a bore in which a pole core 3 is permanently connected with the lowest possible magnetic resistance losses. An excitation winding 2 having connections (not shown in detail) for the supply of current is mounted on the pole core 3. The longitudinal axis of the pole core 3 is at right-angles to the axis of rotation of the motor and at right-angles to the surfaces of the stator laminations. At its end face remote from its point of attachment to the stator lamination 1, the pole core 3 defines a double D-shape, in a manner comparable to that of a screw head.This end face supports a copper sort-circuiting ring 4 or the like, which, when a load is applied, contributes to stabilising the armature in manner known per se, i.e. so that oscillations of the hinged armature which might be produced by the alternating field are damped or completely eliminated.

The second stator lamination 5, which is located facing and parallel to the stator lamination 1 and which supports the ciaw poles 5.1 engaging between the claw-poles 1.1, also comprises a portion which overlaps the synchronous motor. This portion supports a yoke projection 5.2 which in the assembled state of the motor adjoins the side of the projection of the stator lamination 1. The yoke projection 5.2 is at right-angles to the rest of the stator lamination 5 and is bent towards the stator lamination 1. In addition, the yoke projection 5.2 projects beyond the rest of the stator lamination 5 so that on the side of the yoke projection 5.2 remote from the rest of the stator lamination 5 there is sufficient space for the excitation coil 2, as shown in Figure 1.This arrangement also ensures adequate operating reliability for a hinged armature 13, which is mounted on the upper edge of the yoke projection 5.2 in the manner shown in Figure 3.

A magnetically insulating part 8, preferably an injection-moulded synthetic material part or the like, is positioned between the two stator laminations 1 and 5 and is retained by engagement in two diametrically opposed bores in the stator laminations 1 and 5. Thus the part 8 simultaneously determines the spacing and parallel arrangement of the two laminations and their centering with respect to each other. On each side and in particular on the inner surface of each of the stator laminations 1 and 5, short-circuiting rings 7 encompass a predetermined claw-pole region and thus define auxiliary and main poles. Bearings 6 consiting of nonmagnetisable material are also inserted in central bores in the stator laminations 1, 5. These bearings provide mountings for a rotor shaft 10 of a permanent magnet rotor 9.The permanent magnet ring of the magnet rotor 9 is polarised so that its peripheral surface consists of uniformly distributed alternate north and south poles. This magnet ring is supported by a synthetic bush 11, which provides a non-rotary connection to the rotor shaft 10.

When a voltage is applied to the excitation coil 2, the hinged armature 13 is tilted by the amount of a working air gap 12.1 (c.f. Figure 1) about a pivot defined by the upper end face of the yoke projection 5.2. The resultant movement of the bent part of the armature 13 which extends in the direction of the motor may be used to close sets of contacts (not shown) with an immediate switching function for example, but can also be used to undertake coupling functions.Closure oftheworking air gap 12.1 has the effect that the entire magnetic circuit flux from the magnetic field produced by the excitation winding 2 in the pole core 3 is closed by way of the armature 13, the yoke projection 5.2 and thus the stator lamination 5 with the pole claws 5.1 on the one hand and by way of the other end of the pole core 3 and the stator lamination 1 with the pole claws 1.1 on the other hand to the working air gap of the synchronous motor, i.e. the air gap between the claw-pole arrangements 1.1 and 5.1 and the permanent magnet rotor 9.The closure of the magnetic circuit flux between the stator pole claws 1.1 and 5.1 and the permanent magnet rotor 9 in practice takes place at the same time as the pivoting operation of the armature 13 and at the same time, even if it is at least theoretically slightly delayed, with the starting-up of the synchronous motor. After the supply of current to the excitation coil 2 is interrupted, the armature 13 pivots back into its inoperative position due to its own weight or to a suitable pre-tensioning force, for example a tension spring or the like (not shown), so that the working air gap 12.1 is opened in the manner shown in figure 1 and the magnetic circuit flux is interrupted. This simultaneously leads to the stopping of the synchronous motor.The synchornous motor can be connected to a time-lapse wheel, which in addition to the above described contacts having an immediate switching action and able to be actuated by the armature 13, is in a position to switch time-lay contacts (not shown).

In the embodiment described in figures 1 to 3, seen magnetically, the air gap 12.1 between the armature 13 and the pole core 3 and the air gap between the pole claws 1.1 and 5.1 of the stator laminations 1 and 5 of the synchornous motor, are in series and the complete construction of a synchronous motor on the one hand and a hinged armature magnet with excitation coil on the other hand is achieved with only a single coil winding.

Figures 4 and 5 respectively show plan and sectional side views of another embodiment of the invention in which a synchronous motor with a permanent magnetic rotor is combined with an electromagnet with a movable armature. In contrast to the embodiment of Figures 1 to 3, in which two series-arranged air gaps are provided, in the embodiment of Figures 4 and 5 two air gaps are arranged in parallel as described below.

Referring to Figures 4 and 5, the illustrated arrangement comprises two stator laminations 1' and 5' which are arranged parallel to each other and at a distance apart. A synchronous motor and an excitation coikl 2' on a pole core 3' are received between the two stator laminations. The axis of the pole core 3' is located at right-angles to the stator laminations 1' and 5', but parallel to a rotor shaft 10' of the synchronous motor, on which a synthetic bush 11' is seated in a non-rotary manner. The peripheral surface of the bush 11' supports an annular magnet 9'. The rotor shaft 10' is mounted in bearings 6', which are retained in corresponding bores in the stator laminations 1' and 5'. As in the embodiment according to figures 1 to 3, claw-poles 1.1' and 5.1' extend from and at right angles to the stator laminations 1' and 5'.The claw poles and directed towards each other and are located in the usual manner on a circle which is concentric with respect to the rotor shaft 10', so that a working air gap 12' is produced between the permanent magnet rotor 9' and the claw-pole arrangement. Shortcircuiting rings 7' divide the claw-poles into auxiliary and main poles. Located from between the two stator laminations 1' and 5' on the pole core 3 is the excitation coil 2'. The axis of the coil 2' is spaced from but parallel to the motor axis. A short-circuiting ring 4' is located adjacent a hinged armature 13'.

When the coil is not excited, an air gap 12.1' opens between the pole core 3' and the armature 13', which is mounted to pivot on the bent end face of a yoke projection 5.2' of the stator lamination 5.

As a modification of the embodiments described according to figures 1 to 5, it is also possible to locate the single excitation winding used both for the armature as well as for the synchronous motor, at any point forming the magnetic circuit, such as for example in the region of one or both stator laminations or between the the stator laminations.

Claims

1. A drive motor comprising a synchronous motor, a movable element, and means for generating a magnetic field to move the movable element to shunt a region of increased magnetic resistance in the magnetic flux path of the magnetic field generating means, characterised in that the magnetic field generating means comprises an excitation winding and a pole core arranged to actuate the movable element and to simultaneously predetermine the magnetic field for the operation of the motor, the motor stator comprising two magnetically nonconducting and interconnected stator laminations which define a closed magnetic circuit with the pole core and the movable element when the movable element is actuated.

2. A drive motor according to Claim 1, characterised in that the magnetic circuit flux for the motor and the movable element passes via two air gaps located in series with regard to the magnetic flux, one air gap being located between stator poles defined by the laminations and a permanent magnet rotor of the synchronous motor, and the other gap being located between the movable element and the pole core.

3. A drive motor according to Claim 1, characterised in that the air gaps between stator poles defined by the laminations and a permanent magnet rotor of the motor and between the movable element and the pole core are parallel to each other in the magnetic circuit.

4. A drive motor according to Claim 1, characterised in that the laminations define surfaces located parallel to each other and between which a permanent magnet rotor is located, the laminations also defining a claw-pole arrangement therebetween, portions of the laminations extending beyond said surfaces comprising projections which are bent towards each other and between which the pole core and the excitation winding are located at rightangles to the axis of rotation of the motor.

5. A drive motor according to Claim 1, characte rised in that the laminations are arranged parallel to each other and the rotor of the synchronous motor and the excitation coil with the pole core are received therebetween, the axes of the rotor and the coil being arranged at right-angles to the surfaces of the laminations.

6. A drive motor according to Claim 1, characterised in that the excitation winding is located at any position in the magnetic circuit.

7. A drive motor substantially as hereinbefore defined with reference to the accompanying drawings.