GB1571876A

GB1571876A - Sandwich synchronous machines and dc machines

Info

Publication number: GB1571876A
Application number: GB1347378A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-04-06
Filing date: 1978-04-06
Publication date: 1980-07-23

Description

(54) SANDWICH SYNCHRONOUS MACHINES AND D.C.

MACHINES (71) I, WAI SUN LEUNG of 140, Pokfulham Road, Flat 65, Hong Kong, British (Hong Kong), do hereby declare the invention, for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: - The present invention relates to a new type of design for synchronous machines and d.c. machines of the planar airgap type.

Each of these machines is fabricated in the form of a sandwich. In the case of a synchronous machine, the stator is in the centre sandwiched between two rotors, and in the case of a d.c. machine, the armature is in the centre sandwiched between two fields. In each machine, there are two planar airgaps across which the reaction between the magnetising flux and the load current will produce the torque and power of the machine.

Fig. la and Fig. ib show the side views of a sandwich synchronous machine and d.c. machine respectively. For simplicity and clarity, the windings and mechanical details have been omitted. The front view of the stator of the synchronous machine is given in Fig. 2. The stator core consists of a number of packets of teeth laminations held together by two endplates. The teeth are made of grain-oriented steel and the endplates are made of a material with a very high electrical resistivity. To fabricate the stator, the teeth alminations are first inserted into one endplate. The stator winding is then wound in place before the second endplate is pressed in position on to the other end of the teeth laminations. The armature of the d.c. machine is assembled in a similar way and the armature winding will be connected to a commutator which may be of either the conventional type or the disc type. Since the teeth are readily accessible, the winding can be wound with a great deal of ease. This will result in reducing the cost of the winding. Compared with the stator core of the conventional synchronous machine or the armature core of the conventional d.c. machine, the use of grain-oriented steel in the new design enables a higher flux density in the teeth to be used resulting in a reduction of core material. In the new design, there will also be no wastage of core material to be stamped out to make room for slots.

Furthermore, there is no return flux path and therefore no yoke in the said stator or said armature core resulting in a considerable saving in the cost of the stator or armature core. Compared with a known stator or armature core of this type formed by cutting out slots on the two sides of a wound core as shown in Fig. 3, the cost of fabricaiton of the core of the new design is much lower because of the high cost for forming the slots. There is also no wastage of core material to be cut away to form the slots. Fig. 4 shows an example of the rotor in the synchronous machine.

This is similar to that of a field in a d.c.

machine. The core of the rotor or field is made of solid steel. The poles may be of the permanent magnet type or of the wound type and they may be secured onto the yoke by any common mechanical means. Any damper windings, compoles, or compensating windings may be added as required.

The number of stators and rotors or armatures and fields may be increased to increase the power of the machine. The modular method of construction of these machines will result in reducing their manufacturing costs. A side view of a synchronous machine with three motors and two stators is shown as an example in Fig.

5. The yoke of the rotor at the centre may be replaced by some means of mechanical support for the poles.

Claims

WHAT I CLAIM IS: -

1 A planar airgap type synchronous machine or d.c. machine in a sandwich form (a) with the synchronous machine stator or the d.c. machine armature sandwiched in the centre between rotors or d.c. fields respectively such that in the said stator or said armature there is no return flux path and therefore no yoke in the said stator core or said armature core which, for accommodating the stator or armature windings, consists of a number of packets of grainoriented steel laminations evenly spaced in a circle and mechanically secured in position by two endplates made of material with very high electrical resistivity and (b) with the said rotors or said d.c. fields consisting of permanent-magnet or wound poles which are mechanically secured onto a yoke which provides the return path for the flux.

2. A planar airgap type sandwich synchronous machine or d.c. machine according to Claim 1 wherein the number of stators and rotors of armatures and fields can be increased to increase the number of planar airgaps resulting in an increase in the power of the machine.