WO2014205524A2

WO2014205524A2 - Brushless alternator with claw poles

Info

Publication number: WO2014205524A2
Application number: PCT/BG2014/000009
Authority: WO
Inventors: Encho Nikolov Popov
Original assignee: Eldix Ltd.
Priority date: 2013-06-24
Filing date: 2014-02-19
Publication date: 2014-12-31
Also published as: BG66662B1; BG111509A; BG1785U1; WO2014205524A3

Abstract

It is designed for re-charging accumulator battery and for producing electric energy with rectified voltage for movable vehicles or for unmovable devices and/or objects. There is reduced radial dimension at increased output current and prolonged lifetime. Part of the cylindrical stator (3) outside surface is smooth and embraced tightly by enveloping front aluminum housing (11a) with square-oval shape united with the front end bell (11b). To the front enveloping aluminum housing (11a) rear enveloping aluminum housing (14a) with the same square-oval shape frontal is pressed and mirror-image disposed to wards the front enveloping aluminum housing (11a). In the corners of the front enveloping aluminum housing (11a) and the rear enveloping aluminum housing (14a) more than two axial ventilation ducts (12) are formed extending from the front enveloping aluminum housing (11a) in the rear enveloping aluminum housing (14a).

Description

BRUSHLESS ALTERNATOR WITH CLAW POLES

FIELD OF THE INVENTION

The present invention relates to brushless alternator with claw pole rotor designed for re-charging accumulator battery and for producing electric energy with rectified voltage for movable vehicles or for unmovable devices and/or objects.

DESCRIPTION OF PRIOR ART

A brushless alternator with claw poles is known [1] including drive shaft whereon two rotor sets with claw poles are stationary fit and mirror-image each towards other disposed. The claw poles envelop cylindrical excitation sets coaxial to the drive shaft. Each rotor set consists of carrying and carried claw pole configurations connected stationary by non-magnetic rings between them. The rotor sets are encompassed by cylindrical stator. The cylindrical stator is disposed in cylindrical housing closed by front and rear end bells with vent-holes. On the drive shaft before front end bell a cooling fan is assembled. The drive shaft is sustained on bearings in front and rear end bells. The cylindrical stator consists of cylindrical pack with formed on its inner surface slots which are on even distribution. In the slots are uniformly laid more than one three-phase windings of round copper isolated wire arranged in groups two by two in common slots. Both groups of three-phase windings are phase - displaced on 60 electric degrees between them. On the outer surface of the cylindrical stator are circularly disposed a plurality of even spaced slots closed outside by cylindrical housing. The even spaced slots function as vent-holes. The excitation sets are jointed to the front and rear end bells. Each excitation set consists of cylindrical magnetic core with cylindrical excitation winding wound thereon. Between the cylindrical magnetic cores of the excitation sets and the cylindrical stator are shaped cylindrical spaces where the excitation sets claw poles are put in with the possibility for their free rotation together with the drive shaft. Each three-phase winding with its own terminals is connected to own rectifier block including also diodes to terminals of wye centre. The positive and negative diodes of three-phase windings rectifier blocks are united in two cylindrical ribbed concentric aluminum rings, each of them arranged frontal on the rear end bell. Closing cover with central vent-hole on the rear end bell is assembled with possibility for connection to air-duct.

Disadvantage of the known alternator is its increased radial dimensions due to the circular disposition and sizable dimensions of the vent-holes around cylindrical stator outside surface.

Other disadvantage is that the increase in the number of parallel working positive and negative diodes necessary at increased output current is limited by concentric frontal arrangement of collector rings of positive and negative diodes, as well as the difficult diodes cooling due to the lack of air vent-holes and ribbing between the outer and inner diodes aluminum rings.

Another disadvantage is also difficult cooling of the rear bearing leading to its lifetime limitation.

SUMMARY OF THE INVENTION

The aim of the invention is to create brushless alternator wit claw pole rotor which to be with reduced radial dimension at increased current output and prolonged lifetime.

The aim is solved by brushless alternator with claw poles comprising a drive shaft sustained on bearings in end bells and with assembled before front end bell cooling fan where on the said drive shaft two rotor sets are stationary fit mirror-image disposed each towards other. Every rotor set consists of carrying and carried claw pole configurations connected stationary between themselves by non-magnetic rings. Said claw poles envelop cylindrical excitation sets coaxial to said drive shaft. Said rotor sets enveloped by cylindrical stator put in cylindrical housing closed by said front and rear end bells with vent holes. Said cylindrical stator consists of cylindrical pack with formed on its inner surface slots which are on even distribution where uniformly more than one three-phase windings are laid. Each said excitation set consists of cylindrical magnetic core whereon cylindrical excitation bobbin is wound. Between said cylindrical magnetic cores of said excitation sets and said cylindrical stator cylindrical spaces are shaped where said claw poles of said excitation sets are put in with possibility for free rotation together with said drive shaft. Each said three-phase winding with its own terminals is connected to own rectifier block including also diodes to terminals of wyes centre. On the rear end bell closing cover with central vent-hole is assembled with possibility for connection to air-duct. Invention is characterized in that part of said cylindrical stator outside surface is smooth and embraced tightly by enveloping front aluminum housing with square-oval shape united with said front end bell forming aluminum body, and to said front enveloping aluminum housing rear enveloping aluminum housing with the same square-oval shape frontal is pressed. Said rear enveloping aluminum housing is disposed mirror-image towards said front enveloping aluminum housing and it is united with said rear end bell in one aluminum body and in the corners of said front enveloping aluminum housing and said rear enveloping aluminum housing more than two axial ventilation ducts are formed extending from said front enveloping aluminum housing in said rear enveloping aluminum housing and separated by partitioned inner ribs which envelop the outer part of said cylindrical stator on its smooth surfaces. In the areas of said cylindrical stator outer surface between said partitioned inner ribs are trapezium shaped grooves and teeth whose radial dimension is not greater than 15% of radial dimension hi of said cylindrical stator yoke and tangential pitch not exceeding the half of tangential pitch of said cylindrical stator inner slots plurality. The enveloped axial dimension of said cylindrical stator pack by said front enveloping aluminum housing is not less than 2/3 of the whole axial dimension of said cylindrical stator pack. Toward said rear enveloping aluminum housing a negative diode aluminum ring is adjoined and fixed with inner and outer cooling ribs with radial pressed negative diodes. On said negative diode aluminum ring axially through isolation positive diode aluminum ring is adjoined and fixed with inner and outer cooling ribs with radial pressed positive diodes. Said drive shaft is with prolonged rear portion protruding out of rear bearing and ribbed aluminum bush frontal to inner ring of said rear bearing is assembled.

Advantage of the brushless alternator with claw pole rotor according to the invention is its reduced radial dimension which is possible owing to square-oval shape of the united front end bell with front housing and the united rear end bell with rear housing. Another advantage is the increased current output due to improved cooling by means of ducts formed in the corner areas of the front and rear housings and the shaped grooves on the outer surface of the cylindrical stator in the zones of axial ducts in the housing as well as inside and outside placed cooling ribs on the axial arranged one on top of the other diode aluminum rings. Advantage is prolonged lifetime owing to rear bearing reduced temperature and more especially of its inner ring.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG.l represents longitudinal section of the alternator embodying the invention;

FIG.2 represents cross-section of the alternator through stator part;

FIG.3 represents alternator frontal view from the side of diode block without rear cover.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In an example embodiment of the invitation the brushless alternator with claw poles (FIG.l) comprises drive shaft 1 whereon front rotor set with claw poles 2a and mirror-image disposed towards it rear rotor set with claw poles 2b are stationary fixed enveloping coaxially to the drive shaft 1 cylindrical mirror-image disposed front excitation 4a and rear excitation 4b sets. The drive shaft 1 is sustained on bearings in end bells with vent-holes. On the drive shaft 1 a cooling fan 5 is fixed. To the rear end bell 14b overlaid cover 7 with central vent-hole 8 is attached serving the purpose of air-feed by air-duct. The front 2a and the rear 2b rotor sets with claw poles are enveloped by cylindrical stator 3 with formed on its inner surface plurality of slots 9. In the stator 3 slots 9 one or more than one three-phase windings 10 are arranged.

At least one third of the cylindrical stator 3 length is enveloped by aluminum body 11 consisting of front housing 11a and front end bell lib. The enveloping front housing 11a is with square-oval shape over the cylindrical stator 3 and partly outside it. In the corners of the enveloping front housing 11a with square-oval shape are formed more than two axial ventilation ducts 12 with partitioned inner ribs 13 between them belonging to front housing 11a of the aluminum body 11. The rest part of cylindrical stator 3 is enveloped by second enveloping body 14 pressed to front housing 11a. The second enveloping body 14 consists of aluminum enveloping rear housing 14a and rear end bell 14b centered by cylindrical stator 3 outer surfaces. The rear aluminum enveloping housing 14a has the same square-oval shape as the enveloping front housing 11a and is mirror-image disposed towards it. The axial ducts in the rear aluminum enveloping housing 14a are prolongation of the axial ventilation ducts 12 shown on FIG.2. The front housing 11a and the rear aluminum housing 14a envelop cylindrical stator 3. The enveloping housings envelop the stator on the smooth surfaces 15 disposed in the zones under square sides and under partitioned internal ribs. In the areas between the partitioned internal ribs 13 on the surface of cylindrical stator 3 are trapezium shaped grooves 16 and teeth 17 with radial dimension not more than 15% of the cylindrical stator 3 yoke radial dimension hi and tangential pitch not exceeding the half of tangential pitch of the cylindrical stator 3 inner slots 9 plurality.

To the rear end bell 14 directly or through isolation negative diode aluminum ring 19 is adjoined and fixed. On the negative diode aluminum ring 19 axially through other isolation 20 positive diode ring 21 is adjoined and fixed. In negative diode aluminum ring 19 negative diodes 22 are upset and in the positive diode ring 21 positive diodes 23 are upset. On the inner and outer surface of the positive diode ring 21 cooling ribs 6a are formed and on the inner and outer surface of the negative diode ring 19 cooling ribs 6b are formed.

The drive shaft 1 is with extended rear portion 24 stretching outside the rear bearing 25. On the extended portion 24 pressed to the inner ring of the rear bearing 25 is assembled ribbed aluminum bush 26.

OPERATION OF ALTERNATOR WITH CLAW POLES

After turning of the brushless alternator with claw poles and current supplying of the bobbins of front 4a and rear 4b excitation sets magnetic fluxes are created passing over claw poles of front 4a and rear 4b rotor sets and cylindrical stator 3. The magnetic fluxes induce electromotive forces in three- phase stator windings 10 and current flows through them. That current generates basic and added losses in three-phase stator windings 10. At the same time magnetic fluxes generates losses in cylindrical stator 3 and other iron parts. Losses are generated also by the current in excitation bobbins of front 4a and rear 4b excitation sets and by the current passing through diodes 22 and 23. By the structured cooling system of ducts for cooling according to the invention and enveloping cylindrical stator 3 by front aluminum 11a and rear aluminum 14a housings, by air passing across axial ventilation ducts, by diode block cooling ribs 6a and 6b and the cooling of rear bearing 25, the temperature of bearings, diodes 22 and 23 and three-phase windings 10 at increased output current will not increase.

EXPERIMENTAL RESULTS RECEIVED BY SAMPLE INVESTIGATION REALISING THE INVENTION

The inventor has made a virtual sample with increased output current from 520 A up to 600 A realizing the invention. Radial dimensions of the brushless alternator with claw poles are reduced by 12% and the weight is reduced by 10%. At the revolutions range from 1250 up to 6000 rpm and the increased output current the three-phase windings 10 and diodes 22 and 23 temperature retains its value and the temperature of inner ring of the rear bearing 25 is reduced leading to increased lifetime of the rear bearing 25.

REFERENCE

[1] EP 0120067

Claims

1. A brushless alternator with claw poles comprising a drive shaft sustained on bearings in end bells and with assembled before front end bell cooling fan where on the said drive shaft two rotor sets are stationary fit mirror-image disposed each towards other, at that every rotor set consists of carrying and carried claw pole configurations connected stationary between themselves by non-magnetic rings and said claw poles envelop cylindrical excitation sets coaxial to said drive shaft, said rotor sets enveloped by cylindrical stator put in cylindrical housing closed by said front and rear end bells with vent holes, said cylindrical stator consists of cylindrical pack with formed on its inner surface slots which are on even distribution where uniformly more than one three-phase windings are laid, each said excitation set consists of cylindrical magnetic core whereon cylindrical excitation bobbin is wound, while between said cylindrical magnetic cores of said excitation sets and said cylindrical stator cylindrical spaces are shaped where said claw poles of said excitation sets are put in with possibility for free rotation together with said drive shaft, whereat each said three-phase winding with its own terminals is connected to own rectifier block including also diodes to terminals of wyes centre, whereas on the rear end bell closing cover with central vent-hole is assembled with possibility for connection to air-duct, characterized in that part of said cylindrical stator (3) outside surface is smooth and embraced tightly by enveloping front aluminum housing (11a) with square-oval shape united with said front end bell (lib) forming aluminum body (11), and to said front enveloping aluminum housing (11a) rear enveloping aluminum housing (14a) with the same square-oval shape frontal is pressed while said rear enveloping aluminum housing (14a) is disposed mirror-image towards said front enveloping aluminum housing (11a) and it is united with said rear end bell (14b) in other aluminum body (14), and in the corners of said front enveloping aluminum housing (11a) and said rear enveloping aluminum housing (14a) more than two axial ventilation ducts (12) are formed extending from said front enveloping aluminum housing (11a) in said rear enveloping aluminum housing (14a) and separated by partitioned inner ribs (13) which envelop the outer part of said cylindrical stator (3) on its smooth surfaces (15), and in the areas of said cylindrical stator (3) outer surface between said partitioned inner ribs (13) are trapezium shaped grooves (16) and teeth (17) whose radial dimension is not greater than 15% of radial dimension hi of said cylindrical stator (3) yoke and tangential pitch not exceeding the half of tangential pitch of said cylindrical stator (3) inner slots (9) plurality, whereas the enveloped axial dimension of said cylindrical stator (3) pack by said front enveloping aluminum housing (11a) is not less than 2/3 of the whole axial dimension of said cylindrical stator (3) pack, while toward said rear enveloping aluminum housing (14a) a negative diode aluminum ring (19) is adjoined and fixed with inner and outer (6b) cooling ribs with radial pressed negative diodes (22), whereat on said negative diode aluminum ring (19) axially through isolation (20) positive diode aluminum ring (21) is adjoined and fixed with inner and outer (6b) cooling ribs with radial pressed positive diodes (23), and said drive shaft (1) is with prolonged rear portion (24) protruding out of rear bearing (25) and ribbed aluminum bush (26) frontal to inner ring of said rear bearing (25) is assembled.