Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-12-14
2002-12-03
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S235000, C310S236000
Reexamination Certificate
active
06489703
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority of Japanese Patent Applications No. H.11-361029 filed on Dec. 20, 1999, No. H.11-361031 filed on Dec. 20, 1999, No. 2000-242689 filed on Aug. 10, 2000 and No. 2000-242690 filed on Aug. 10, 2000, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a commutator forming plate, a commumator in use of the commutator forming plate, a motor incorporating the commutator and a method of manufacturing the same.
2. Description of Related Art
Conventionally, a commutator forming plate is provided with a plurality of lands extending in parallel to each other and protruding portions formed in each of the lands nearly perpendicular to an extending direction of the land. After forming the basic plate to a cylindrical shaped member so as to locate the lands on an inner circumferential side thereof and an inside of the cylindrical shaped member is filled with a resin element, the cylindrical shaped member is cut into small pieces to constitute a plurality of commutator segments. Each of the commutator segments is firmly fixed to the resin element by holding a part of the resin element in the protruding portions.
The conventional commutator forming plate, as shown in JP-U-61-202163, is generally flat and is provided with a plurality of grooves to constitute a plurality of lands whose respective rising portions perpendicular to respective bottoms of the grooves extend linearly along the grooves. Each of the lands is provided at the rising portions thereof with projecting portions protruded respectively in opposite directions (toward the respective adjacent grooves) and on an upper surface thereof with a letter V shaped groove extending in a longitudinal direction thereof. The projecting portions are formed in such a manner that the upper surface is pressed down so as to push out respective peripheries along the grooves outwardly (toward the respective adjacent grooves) when the letter V shaped groove is formed.
The commutator forming plate is rounded to constitute a cylinder in which the lands are located inside. Then, liquid resin is poured into the cylinder and, after resign has hardened, the cylinder is cut axially into a plurality of pieces at constant angular intervals to constitute a plurality of commutator segments which are insulated with each other via hardened resin (insulator). As the respective lands having the projecting portions are rigidly engaged with the insulator so that the respective commutator segments are prevented from coming off the insulator.
In another conventional commutator forming plate, as shown in
FIG. 14
, projecting portions
53
protruding toward the respective grooves
52
are formed by pressing down and crushing outer peripheries of the lands
51
at intervals in a longitudinal direction thereof. As the projecting portions
53
are located inside a cylinder formed by rounding the commutator forming plate and are engaged with resin poured into and hardened in the cylinder, each of commutator segments
54
formed by dividing the cylinder is prevented from coming out the insulator.
However, in the conventional commutator forming plate disclosed in JP-U-61-202163, there is a drawback that, if the letter V shaped groove extending in a longitudinal direction of the land is formed so as to locate at a position a little bit away from the outer periphery of the land, the outer periphery is unlikely to be sufficiently pushed outwardly and, accordingly, the projecting portion sufficiently protruding cannot be formed. To cope with this problem, a highly accurate positioning is required when the letter V shaped grooves are formed.
Further, in the conventional commutator forming plate shown in
FIG. 14
, complicated metal dies are required to form a necessary number of the projecting portions
53
at the same time. Furthermore, as the projecting portions
53
are formed by crushing predetermined portions of outer peripheries of the lands, each position of the projecting portions
53
in an arising direction of the land
51
is considerably low relative to the upper surface of the land
51
(near the bottom of the groove). When the projecting portion
53
is located at a lower position, the insulator put between the projecting portion
53
and the bottom of the groove
52
is likely to be broken so that the commutator segment may easily come out from the insulator. Therefore, to put the projecting portion
53
at a higher position, a higher thickness of the land
51
becomes necessary, thus, resulting in increasing material cost.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a commutator forming plate to be rounded into a cylinder which is to be cut at constant angular intervals to form a plurality of commutator segments after being filled with insulating material, in which projecting portions protruding nearly perpendicular to a rising direction of the land are located near an outer periphery of an upper surface of the land so that the insulator may firmly hold each of the commutator segments.
Another object of the present invention is to provide a method of manufacturing the above commutator forming plate in which the projecting portions are easily and reliably formed.
It is a further object to provide a commutator made of the commutator forming plate mentioned above and a method of manufacturing the same.
Furthermore, to provide a motor incorporating the commutator mentioned above is one of the present inventions.
To achieve the above objects, the commutator forming plate have a plurality of lands rising at given intervals in a thickness direction thereof to constitute flat upper surfaces on tops thereof. Each of the upper surfaces has at least one of outer periphery lines. Each of the lands is provided with a plurality of grooves which intersect obliquely with the outer periphery line of the upper surface so as to constitute an acute angle edge and an obtuse angle edge on the upper surface. Each of the lands is further provided with a plurality of projecting portions protruding nearly perpendicularly to a rising direction of the land from the land in a vicinity of the acute angle edge.
As each of the grooves intersects obliquely with the outer periphery line of the upper surface, an acute angle edge and an obtuse angle edge are provided in each intersecting portion of the upper surface. When the upper surface is pressed down to form the grooves, for example, by press forming or roller forming, the land is easily deformed outwardly at the same time, even if the pressing force is relatively small, at portions in a vicinity of the acute angle edges, whose each volume is smaller than that of the obtuse angle edges, so that the projecting portions may be formed. Further, it is not always necessary for forming the above projecting portions to accurately position the groove relative to the outer periphery line of the upper surface if the groove intersects obliquely with the outer periphery line of the upper surface.
It is preferable that the groove has a letter V shaped cross section. A portion of the land adjacent to the groove and nearer to the upper surface, which is more largely deformed, has a larger projecting portion.
Further, preferably, each of the grooves extends from one point of the outer periphery line of the upper surface to another point of the outer periphery line thereof so as to divide the upper surface. With this construction, two projecting portions are formed on the outer periphery line of the land at the same time by pressing down the upper surface to form the groove.
Furthermore, it is preferred that the grooves are arranged to extend to cross with each other on the upper surface. In this case, the projecting portions may be continuously formed along the outer periphery line constituting one side of a triangle formed by the grooves crossing with each other and intersecting with the outer periphery line.
Moreover, the lands are arr
Kanno Kazunobu
Kasao Nobuo
Terada Yuuichi
Asmo Co. Ltd.
Law Offices of David G. Posz
Nguyen Tran
LandOfFree
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