MXPA98000810A - Rotor alternator with permanent magnet - Google Patents

Abstract

A rotor alternator with a permanent magnet is described, consisting of a rotor hub, a steering wheel and a starter gear in one piece. Three permanently remanent ceramic permanent magnets provide a rotor that has a continuous ring of twelve alternating poles, which allows a higher performance of the alternator. The magnets are ceramic and are adhesively bonded to the rotor hub, which is driven by an extended crankshaft. The rotor rotates within a stator winding assembly, whose laminated stator core forms part of the alternator frame assembly, and thus acts as protection in the event that a rotating magnet is released.

Description

ROTOR ALTERNATOR WITH PERMANENT MAGNET BACKGROUND OF INVENTION Field of the Invention The present invention relates, in general, to rotor alternators with permanent magnet for internal combustion engines and, specifically, to a rotor alternator with permanent magnet where the rotor hub is part integral of the flywheel / starter gear of the internal combustion engine.

Description of Previous Inventions Many of the automotive type alternators use winding stator and rotor assemblies. An electromagnetic force is produced in and around the rotor windings by the admission of electrical current through the rotor windings.

As the magnetic field produced by the rotating rotor is coupled to the stator windings, current is induced in the stator windings. This type of alternators needs to have brushes or collector rings to maintain a closed circuit to admit the necessary current in the rotor while it is rotating. These mechanical connections are vulnerable to wear and corrosion. It is also common to find disturbances of electrical origin, which can affect other sensitive electronic devices that many modern cars have.

Rotary alternators with a permanent magnet do not need power to be fed to the rotor. The field inherent in the magnetic material, and generated by it, induces current in the stator when the poles of the magnet move relative to the windings of the stator. Because there is no need to feed current to the rotor, collector rings or brushes are not necessary. As a result, disturbances of electrical origin and wear related to this type of alternators that use these elements are eliminated.

Those of skill in the art will appreciate that although traditional regulating means for rotor wound systems, for example control or field current in the rotor windings, are not applied to permanent magnet rotor alternators, they have been applied. employee, efficiently and reliably other means such as those that implement bipolar SCR devices, a bridge rectifier, and related circuits. The regulation is achieved by short-circuiting the output current so that it does not exceed the requirements of the system, while ensuring that the battery is not short-circuited.

For many years rotor alternators with permanent magnet and magnets have been used successfully in small industrial engines and in marine applications. Although the rotor often forms an integral part of the starting flywheel / gear, the systems of the prior inventions have several disadvantages. Generally, a cup-shaped rotor assembly is used. At the inner edge of the "cup" are attached individual magnets, and the annular gear is welded to the outer edge, or press fit therein, to allow the gear to be driven by a starter motor. In systems such as this, the stator is in the inner part of the rotor assembly, with which the external rotating rotor assembly is exposed. This arrangement is very voluminous and poses a potential danger if one of the magnets is released when rotating at many revolutions per minute. Also the fact that a magnet is released can dynamically unstable the system. An additional reinforcement could be used to prevent the release of a magnet, but adding a reinforcement would make the system more bulky, expensive and complex. You can see examples of devices of previous inventions patented in the U.S. Patent Number 4,345,553 (Magrane et al.); U.S. Patent Number 3,955,550, (Carlsson); U.S. Patent Number 3,140,413, (Terry et al.); U.S. Patent Number 2,976,439, (Kie haefer); and U.S. Patent Number 2,856,550 (Phelon).

Accordingly, an object of the present invention is to provide a permanent magnet rotor alternator.

Yet another object of this invention is to provide an improved permanent magnet rotor alternator, in which the rotor hub forms an integral part of the starting flywheel / gear of an internal combustion engine.

Yet another object of this invention is to provide a less complex improved permanent magnet rotor alternator.

Yet another object of this invention is to provide an improved permanent magnet rotor alternator having greater inherent safety.

Yet another object of this invention is to provide an improved permanent magnet rotor alternator of higher efficiency.

In summary, this and other objectives can be achieved with an alternator system with a rotor of permanent magnet and stator winding, a rotor assembly forming in a single piece the flywheel / starter gear, which uses three ceramic permanent magnets of high remanence, magnetizing each magnet with four alternating poles, and being adhered to the hub of a rotor, in contact relation, to create a continuous ring of twelve alternating poles, and an external winding stator consisting of a laminated core that is part of a frame assembly which is directly attached to the engine block of an internal combustion engine.

Other objects and features of the present invention will become obvious in the following detailed description that is made of the preferred embodiment.

Brief Description of the Drawings This invention will be described in more detail in conjunction with the accompanying drawings, in which: Figure 1 is a rear view of a small internal combustion engine having a permanent magnet rotor alternator constructed in accordance with a preferred embodiment of the invention;; Figure 2 is a rear view of the integrated rotor hub according to a preferred embodiment of the invention; Figure 3 is a side view of the integrated rotor hub according to a preferred embodiment; Figure 4 is a rear view of the integrated rotor hub with adhesively bonded permanent magnets, according to a preferred embodiment of the invention; Figure 5 is a side view of the integrated rotor hub with adhesively bonded permanent magnets according to a preferred embodiment of the invention; Figure 6 is a view of the stator assembly according to a preferred embodiment of the invention; Figure 7 is a view of the rotor and stator assemblies in concentric relation according to a preferred embodiment of the invention; Figure 8 is a view of the rotor and the set of laminated parts of the magnetic circuit according to a preferred embodiment of the invention, indicating the direction of flow; Figure 9 is a cross-sectional view of the rotor and stator assemblies in concentric relation, according to a preferred embodiment of the invention; Figure 10 is a rear view of the permanent magnet rotor alternator, according to a preferred embodiment of the invention; Figure 11 is a general side view of the permanent magnet rotor alternator, according to a preferred embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the figures, in which like reference numbers indicate equal elements in all the views and, in particular, with reference to Figure 1, a rear view of a small industrial internal combustion engine having an electric motor alternator is illustrated. rotor with permanent magnet 10, according to the invention. Also illustrated are the end frame 12, the lugs 14, the drive core 16 and the starter motor 18. The alternator 10 is fixedly attached to the engine block (not shown). The rotor assembly of the alternator 10 is driven by means of a motor crankshaft (not shown). The crankshaft extends axially from the engine to make contact with a hub of the rotor 20, which forms an integral part of the flywheel / engine starting gear. These characteristics will be described in more detail when referring to the figures that reveal these characteristics more.

Referring now to Figures 2 and 3, the back and side views, respectively, of the one-piece assembly including the rotor hub, the flywheel and the starter gear are illustrated. From now on, in this specification the alternator 10 will be simply referred to as the hub 20. The hub 20 has two cylindrical shapes that distinguish it from the ordinary starter / flywheels. First, the extrusion 22 of the hub 20 extends axially from the flywheel 24. The flywheel 24 has gear teeth 26 which allow the flywheel 24 to act as a starter gear. Second, its drive core 16, as previously mentioned, which extends axially from the extrusion 22. The use of the term "extrusion" does not describe a manufacturing process, but only suggests a geometric relationship. It is important to realize that although the flywheel 24, the gear teeth 26, the extrusion 22 and the drive core 26 are indicated separately, they all constitute devices integrating the one-piece hub 20. In addition, they are symmetrically arranged and centered along a single axis, which is common, too, to the extension of the crankshaft. Screw holes 28 are also illustrated that allow the coupling of a cooling fan that will be shown later. The drive core 26 is drilled and taper to thereby create the threaded holes 30, which allow a load element to be attached to the hub 20 for different industrial applications. The center of the drive core 16 is rebored, as shown in Figure 2 at site 32. Throughout the thickness of the extrusion 22 the hub 20 is machined to allow the extension of the crankshaft, which is tapered and keyed, fixedly matches the hub 20. The extended crankshaft end is threaded to allow a nut to hold the hub 20 to the threaded portion of the crankshaft extending toward the counterbored portion of the drive core 16.

Referring now to Figures 4 and 5, which respectively illustrate the rear and side views of a complete rotor assembly 40, three permanent magnets 42 are shown attached around the hub 20. Specifically, the magnets are placed in a plane, around the extrusion 22, which is distant from the flywheel 24. The hub 20 is made of low carbon steel and has sufficient mass so as not to saturate, with respect to the magnetic flux, and, consequently, allows a low reluctance flow guide for the resulting magnetic field. In this embodiment, the magnets 42 can be Ferrimag 8A ceramic permanent magnets that can be obtained in Crucible Magnetice from Elezabethtown, Kentucky, or can be any high retentivity magnet available in the market. The high remanence magnets are suitable for those applications in which the magnets suffer excessive vibrations and blows because the intensity of the flow of the magnet can not be reduced. The magnets 42 are attached to the hub 20 by a structural adhesive. Some of the suitable adhesives for this application are ELMS 702-98, which can be obtained from Engineering Systems Inc. of Worthington, Ohio, and Loctite 334, available from Loctite Corporation of Rocky Hill, Connecticut. Adhesives are used because they provide exceptional strength and also excellent resistance to moisture, salts and chemicals. It is also unlikely that these adhesives decompose due to heat fatigue when there are high temperatures and, consequently, constitute a means of secure attachment. The use of adhesives, instead of more elaborate mechanical coupling means, simplifies the manufacturing process and reduces the number of pieces of the system, thus lowering costs.

Referring now to Figure 6, a view of the stator assembly 50 is illustrated., as it would be seen before being placed on the magnets 42. The stator assembly 50 has a simple stator circuit of continuous winding, forming eleven poles of the stator, 52 and a cylindrical laminated core 54. In the present embodiment it is employed a magnetic wire winding 25 of # 14 that winds around each of the eleven poles of the stator. The direction of the winding is reversed from one pole of the stator to the next. The inversion of the winding at the poles is necessary because at the instant when the polarity of the magnet changes with respect to any stator pole, the adjacent stator poles undergo the opposite change of magnetic polarity and, consequently, the current induced in a The stator pole is in the opposite direction to the current induced at the adjacent stator poles. If the winding were done in the same direction, the opposite currents would create a null value field. It will be obvious to those who have knowledge of the technique, that two or more stator circuits can be used, so that the direction of the winding can be arbitrary as long as the currents are suitably added. The finished windings are coated and cured with epoxies, which provides structural integrity and electrical insulation that adds security to the entire system. The laminated cylindrical core 54 is constituted by 35 pieces of silicon steel M19C5, and each laminate has a thickness of 2.22 centimeters. A further characteristic of the core 54 is that it has an arched intrusion 56, which sacrifices the twelfth pole of the stator. The arcuate intrusion 56 provides space to accommodate the differential pinion of the starter 18 (not shown) when it does not engage the gear teeth 26. In other words, the differential pinion is stored in this area.

Figure 7 illustrates a view of the assembly of the stator 50 and the rotor assembly 40 in suitable concentric relation. The magnets 42 are shown indicating how they are polarized. That is, each of the three magnets 42 is magnetized with four alternate poles, NS-SN-NS-SN. The three combined magnets create twelve poles of alternating polarity. To minimize the flow losses, in this case an air gap of not more than 0.0762 cm is maintained between the magnets 42 and the stator poles 52. Also because the magnets 42 are positioned radially around the extrusion 22 to form a continuous ring of alternating polarity, no reduction of the flow intensity takes place between each of the magnets 42, which results in higher efficiency of the alternator. The systems of previous inventions use separate individual magnets, generally having a ferrous material between each magnet. Because the ferrous material has some reluctance, the intensity of the flow from one magnet to another is considerably reduced before changing the polarity. Figure 8 illustrates the direction of flow in the rotor assembly and in the stator assembly, as indicated by the arrows and dotted lines 55. For clarity, the stator windings are not shown.

Referring now to Figure 9, a cross-sectional view of the assembly of the stator 50 and the rotor assembly 40, in suitable concentric relation, is shown through the hub axis 20. It can be seen that the hub 20 is machined for the tapered extension , keyed and screwed on the crankshaft, as previously mentioned. These characteristics can be clearly seen in the cross section generally indicated at site 58. Magnets 42, holes for screws 28 and threaded holes 30 are also illustrated.

Figure 10 illustrates the rear view of the alternator 10. A partial section of the end frame 12 is shown. The cooling fan 60, having eight vanes 62, is shown attached to the hub 20. The distance ring 64 is also exposed, which it is circular with the exception of the protrusion 66. The spacer ring 64 has a vent hole (not shown) to allow the air extracted by the fan 60 through the alternator 10 to be dehausted. The starter motor 18, the differential pinion 68, the retaining ring 70 of the pinion and the pinion shaft 72 are shown. The pinion gear 68 is positioned within the extrusion 56 and the boss 66. When the motor is Starting 18, the pinion 68 is pulled forward to mesh with the gear tooth 26. A nut 74 is shown attached to the threaded end 78 of the crankshaft 76 to hold the rotor assembly 40 to the crankshaft.

Referring now to Figure 11, which generally illustrates a side view of the alternator 10, the fan 60, the stator poles 52, the end frame 12, the spacer ring 64, and a front frame 80, are shown transversally and off center to show more of the internal elements than what could be shown in a profile view. The end frame 12 coincides with the laminated core 54, which in turn coincides with the spacer ring 64, which in turn coincides with the front frame 80. The whole assembly is fastened with threaded bolts inserted into the holes of the lugs 14 and screwed into the threaded holes of the lugs 82 of the front frame. This arrangement allows the alternator 10 to be assembled and disassembled completely, if necessary, easily and quickly.

Although the present invention has been fully described in relation to the preferred embodiment thereof, with reference to the accompanying drawings, it should be noted that for those who have knowledge of the art the various changes and modifications that may be made will be obvious. It should be understood that such changes and modifications are included in the scope of the present invention as defined by the claims set forth below, unless departing from the spirit thereof.

Claims (26)

E IS CLAIMED IS:
1. An alternator for use with an internal combustion engine, which consists of the following: a rotor assembly; a stator assembly; and a housing, said housing having means for securing said stator assembly to said housing and for aligning said stator assembly with said rotor assembly, said rotor assembly comprising a rotor hub and several permanent magnets, said hub having said rotor a disk portion and having gear teeth disposed annularly along the perimeter of said disk portion, and a cylinder portion extending longitudinally from said disk along a rotational axis of said disk, said permanent magnets being fixedly attached to said rotor hub and arranged on an outer peripheral surface of said cylinder portion, said stator assembly comprising a stator circuit wound on a cylindrical core and said cylinder portion being said said permanent magnets of said rotor assembly arranged within said cylindrical core, and concentrically thereto, said conjugation stator number.
2. The alternator of claim 1, characterized in that said permanent magnets are magnetized, at least, with a pair of alternating poles.
3. 3. The alternator of claim 1, characterized in that said permanent magnets are ceramic permanent magnets of high remanence.
4. 4. The alternator of claim 2, characterized in that said permanent magnets are ceramic permanent magnets of high remanence.
5. 5. The alternator of claim 1, characterized in that said permanent magnets are adhesively attached to said rotor hub.
6. 6. The alternator of claim 2, characterized in that said permanent magnets are adhesively attached to said rotor hub.
7. 7. The alternator of claim 3, characterized in that said permanent magnets are adhesively secured to said rotor hub.
8. 8. The alternator of claim 1, characterized in that said permanent magnets form a continuous ring of alternating magnetic polarity.
9. 9. The alternator of claim 1, characterized in that said rotor hub contains means for attaching a cooling fan.
10. 10. The alternator of claim 1, characterized in that said rotor hub includes means for connecting to a crankshaft.
11. 11. The alternator of claim 1, characterized in that said housing means includes said laminated metal core.
12. 12. A rotor of permanent magnet, constituted by the following: a metallic base that rotates around an axis; and a variety of permanent magnets attached to said base, each of said plurality of permanent magnets being in contact relation with one another and arranged to circularly surround a peripheral outer surface of said base.
13. 13. The permanent magnet rotor of claim 12, characterized in that said diversity of permanent magnets are attached to said base with an adhesive.
14. 14. The permanent magnet rotor of claim 12, characterized in that said diversity of permanent magnets are ceramic magnets.
15. 15. The permanent magnet rotor of claim 12, characterized in that said permanent magnets making contact with each other form a continuous ring of alternating magnetic polarity.
16. 6. An alternator for use with an internal combustion engine, which consists of the following: a rotor assembly; and a stator assembly, said rotor assembly comprising a rotor hub and several permanent magnets, said rotor hub having a disk portion and having gear teeth disposed annularly along the perimeter of said disk portion, and a portion of the cylinder extending longitudinally from said disk along a rotational axis of said disk, said permanent magnets being fixedly fixed to said rotor hub and arranged on an outer peripheral surface of said cylinder portion, said assembly consisting of stator of a stator circuit wound on a cylindrical core and said cylinder portion with said permanent magnets of said rotor assembly disposed within said cylindrical core, and concentrically thereto, of said stator assembly.
17. 17. The alternator of claim 16, characterized in that said permanent magnets are magnetized, at least, with a pair of alternating poles.
18. 18. The alternator of claim 16, characterized in that said permanent magnets are ceramic permanent magnets of high remanence.
19. 19. The alternator of claim 17, characterized in that said permanent magnets are ceramic permanent magnets of high remanence.
20. 20. The alternator of claim 16, characterized in that said permanent magnets are adhesively secured to said rotor hub.
21. 21. The alternator of claim 17, characterized in that said permanent magnets are adhesively secured to said rotor hub.
22. 22. The alternator of claim 18, characterized in that said permanent magnets are adhesively secured to said rotor hub.
23. 23. The alternator of claim 16, characterized in that said permanent magnets form a continuous ring of alternating magnetic polarity.
24. 24. The alternator of claim 16, characterized in that said rotor hub contains means for attaching a cooling fan.
25. 25. The alternator of claim 16, characterized in that said rotor hub includes means for connecting to a crankshaft.
26. 26. The alternator of claim 16, characterized in that said housing means includes said laminated metal core.