US 3218492 A
Description (OCR text may contain errors)
R. BAEITZKA Nov. 16, 1965 MAGNETO Filed Aug. 29, 1962 HIS A T'ORNE United States Patent O 3,218,492 MAGNETO Rudolf Babitzka, Ludwigsburg, Germany, assignor to Robert Bosch G.m.b.H., Stuttgart, Germany Filed Aug. 29, 1962, Ser. No. 220,311 Claims priority, application Germany, Sept. 21, 1961, B 64,076 6 Claims. (Cl. 310-70) The present invention relates to magnetos. More particularly, the invention relates to magnetos or dynamo magnetos of the type wherein a retainer plate supports the armature of the ignition system, an interrupting device which cooperates with such armature and, in certain instances, one or more additional (light) armatures.
Heretofore, such retainer plates were made by die casting of aluminum, zinc or an equivalent metallic substance. The armature of the ignition system, the elements of the interrupting device and, in certain instances, the armature or armatures of the lighting system are secured to the plate in a series of operations, mainly by means of screws or bolts. Metallic retainer plates are rather eX- pensive in addition to being heavy so that the overall weight of the magneto is considerable, especially if the magneto is to be used in connection with smaller internal combustion engines.
Accordingly, it is an important object of the invention to provide a magneto which is of lightweight construction, which may be manufactured and assembled at reduced cost, and whose durability or performance is not affected by the fact that it is a low-cost instrument.
Another object of the invention is to provide a novel retainer plate for magnetos of the type utilized in automotive vehicles and for similar purposes.
A further object of the invention is to provide a lowcost retainer plate for the armature or armatures and for the interrupting device of a magneto.
Still another object of the invention is to provide a retainer plate of the just outlined characteristics which simultaneously provides a protective mantle for the armature of the ignition system.
An additional object of my invention is to provide a retainer plate of the above outlined characteristics which may be manufactured in simple and inexpensive machines.
With the above objects in View, the invention resides in the provision of a magneto which comprises a retainer plate adapted to support or to accommodate the armature of the ignition system and wherein this retainer plate consists of rigid synthetic plastic material, such as propylene or polypropylene, which may but need not be reinforced by one or more plate-like metallic inserts.
The retainer plate may be formed with a recess or cutout for the armature (i.e., the coil and the core of the ignition system), or the plate may comprise a specially contigurated portion which forms a mantle about the armature.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of certain specific embodiments with reference to the accompanying drawings, in which:
FIG. l is a top plan view of a retainer plate which embodies one form of my invention;
FIG. 2 is a section as seen in the direction of arrows from the line lI-II of FIG. l, showing a first metallic insert which is partially embedded in the rigid plastic material of the retainer plate;
3,218,492 Patented Nov. 16, 1965 FIG. 3 is a section as seen in the direction of arrows from the line Ill--III of FIG. 1 showing a second metallic insert which reinforces the retainer plate and which may serve as a conductor of highor low-voltage current;
FIG. 4 is a top plan view of a modified retainer plate which defines a mantle for the armature of the ignition system; and
FIG. 5 is a section as seen in the direction of arrows from the line V-V of FIG. 4, showing a tubular portion of the plate which surrounds the high-tension connector of the armature.
Referring now in greater detail to the drawings, and first to FIG. l, there is shown a retainer plate 10 which consists of rigid synthetic plastic material, for example, propylene, and which is manufactured by an injection molding process. An important advantage of propylene is that it can be molded with ease and because of its resistance to the action of heat and its electric characteristics, it is especially valuable in a magneto. This plate 10 is formed with two slit-shaped openings 11 for the passage of screws, bolts 0r similar fastening members by means of which the plate may be secured to the crank case of an internal combustion engine. In addition to the openings 11, the plate 10 is formed with a pair of round openings 12 which receive bolts or screws (not shown) used for securing to this plate an armature of the ignition system. This armature (including a core and a coil) is accommodated in a rectangular cutout or recess 14 which is formed between the openings 12. A further opening 13 serves to permit passage of the through shaft which carries the rotor and the customary breaker cam to operate the interrupting device.
FIGS. 2 and 3 show that the plate 10 is provided with plate-like metallic inserts 15, 16 which are partially embedded in the plastic material and which are formed with openings registering with the respective openings 11. The purpose of the inserts 15, 16 is to reinforce the retainer plate and/or to conduct ignition or lighting current.
FIGS. 4 and 5 illustrate a modified retainer plate 20 which is made by injection molding of polypropylene and which is formed with an integral tubular portion 21 de ining a mantle around the armature 22. This armature comprises a core 22a having lug-shaped portions 22b projecting from the mantle 21 and formed with openings 27 which are aligned with similar openings of the retainer plate 20 so that they permit passage of fastening members for connecting the plate 20 to the crank case of an internal combustion engine. The high-tension connector 23 of the armature 22 is surrounded by a tubular portion 24 which constitutes an integral part of the retainer plate 20.
In assembling the magneto, the armature 22 is inserted into the mantle 21, and the interrupting device 25 is mounted in a subsequent operation. As shown in FIG. 4, the retainer plate 20 also supports a condenser 26. In the final step, the current-conducting and/or generating parts of the magneto are connected by suitable wiring which is not shown in the drawings.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.
What is claimed as new and desired to be secured by Letters Patent is.
1. In a magneto, in combination, an armature; a onepiece retainer plate, said plate consisting of rigid synthetic plastic material and comprising two portions one of which is tubular and the other of which has a support face, said tubular portion surrounding and constituting an insulating mantle for said armature; and magneto parts mounted on said support face of said other portion of said retainer plate'and connected to the armature in said mantle.
2. A combination as set forth in claim 1, wherein said armature comprises a core having portions projecting from said mantle, said plate and said core portions having registering openings for fastening members by means of which said plate may be xed to the case of an internal combustion engine.
3. A combination as set forth in claim 1, wherein said armature comprises a high-tension connector and said plate comprises a tubular portion surrounding said connector.
4. A combination as set forth in claim 1, wherein said retainer plate consists of polypropylene.
5. A combination as set forth in claim 1, wherein said retainer plate consists of propylene.
6. In a magneto, in combination, an armature; a onepiece retainer plate, said plate consisting of rigid synthetic plastic material and comprising two portions one of which embraces the armature so as to consitute an insulating cover for the part of the armature embraced thereby, and the other of which has a support face; and magneto parts mounted on said support face of said other portion of said retainer plate and connected to said armature embraced by said one portion.
References Cited by the Examiner UNITED STATES PATENTS 2,445,986 7/1948 Adamson 310-43 2,688,103 8/1954 Sheldon S10-.43 2,978,598 4/1961 -Kato 310-43 3,002,261 10/1961 Avila et al. 310-43 ORIS L. RADER, Primary Examiner.
MILTON O. HIRSI-IFIELD, Examiner.