Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1998-06-30
2001-03-13
Young, Lee (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S597000, C029S598000, C310S261100
Reexamination Certificate
active
06199265
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of securing the magnets of a revolving electric machine in position. More particularly, this invention relates to a method of rigidly securing magnets to the yoke of the stator of an electric motor (hereinafter referred to as motor) or that of the rotor of a magnet generator (fly-wheel magnet generator), which method may find a wide variety of applications in the field of manufacturing motors to be used for the electric equipment of automobiles.
2. Related Art Statement
Electric motors comprising a plurality of magnets arranged annularly and peripherally at regular intervals along the inner peripheral surface of a hollow cylindrical yoke and rigidly secured in position by means of a hollow cylindrical magnet cover press-fitted to the inner peripheral surfaces of the magnets are widely used as the electric equipment of automobiles.
As a conventional magnet securing method such as the above kind, there is a magnet cover built-in method for a permanent magnet motor shown in Japanese Patent Publication No. 5-59661. With the disclosed method of arranging a built-in type magnet cover, a hollow cylindrical yoke having openings at the opposite ends is used in an ingenious manner. More specifically, magnets are arranged annularly and peripherally at regular intervals along the inner peripheral surface of the yoke and supported by a magnets-aligning jig introduced from one of the openings of the yoke, and a magnet cover is introduced from the other opening of the yoke and press-fitted to the inner peripheral surfaces of the group of magnets.
However, with the above described method, if a yoke with a closure wall end is used, the jig or the magnet cover cannot be introduced from the side of the closure wall of the yoke and it is impossible to arrange the magnet cover within the yoke.
This problem may be bypassed by providing the closure wall of the yoke with an opening, through which the jig can be introduced to align and support the magnets. Then, however, the stator of the motor has to be provided with a sealing means for hermetically sealing the opening that is used to introduce the jig in order to align the magnets. Otherwise, the motor will be devoid of water-resistance.
SUMMARY OF THE INVENTION
Therefore, the object of the present invention is to provide a method of rigidly securing the magnets of a revolving electric machine in position, with which magnets can be rigidly secured to a hollow cylindrical yoke having an end closed without forming an opening through the closure wall of the yoke.
According to the invention, the above object is achieved by providing a method of securing magnets of a revolving electric machine such that a plurality of magnets are annularly and peripherally arranged at regular intervals on the inner peripheral surface of a hollow cylindrical yoke having a closed end and rigidly secured by a hollow cylindrical magnet cover press-fitted to the inner peripheral surface of the magnets, characterized by comprising steps of:
temporarily holding the magnet cover by means of a lower die of a press frame having upper and lower dies to be closed relative to each other and arranging the plurality of magnets peripherally along the outer periphery of the magnet cover; and
securing the yoke to the upper die, arranging the yoke coaxially relative to the magnet cover with the opening side of the yoke directed to the magnet cover, closing the upper die and the lower die relative to each other and then press-fitting the magnets and the magnet cover into the yoke, while pushing the outer peripheral surfaces of the magnets by means of the inner peripheral surface of the yoke.
Further, the magnets arranged along the outer periphery of the magnet cover may be supported by a pair of anti-fall jigs for the magnets until the magnets are partly introduced into the yoke.
Additionally, the anti-fall jigs may be arranged radially movably relative to the upper and lower dies and the magnets arranged along the outer periphery of the magnet cover may be pushed radially from outside by the anti-fall jigs.
Furthermore, the magnet cover may be held by a magnet cover holding member vertically movably fitted to the lower die.
Additionally, the cover holding member may operate also as an anti-fall jigs for holding the magnets and the magnets may be axially pushed from outside by the magnet cover holding member.
For the purpose of the invention, the lower die may be provided with a resilient member adapted to abut the inside of the top of the magnet cover when the magnet cover is temporarily held by the lower die, the resilient member is compressed and radially and outwardly bulged by closing the upper and lower dies relative to each other, so that the magnet cover is bulgy deformed and positioned axially.
Further, a radially and outwardly projecting outside collar may be formed at an end of the magnet cover and provided with as many small holes as the magnets, the small holes being arranged at regular intervals corresponding to the intervals of the magnets; and
the lower die may be provided with aligning projections adapted to be received respectively by the small holes in order to peripherally align the magnets when the upper and lower dies are closed relative to each other.
With a method according to the invention, since when the magnets are secured by the magnet cover the magnets and the magnet cover are positioned in the yoke and the lower die, receiving the reaction force of the yoke, is introduced into the yoke through the opening thereof and, while the yoke is pressed by the upper die. Thus, the yoke does not have to be provided with through holes bored through the closure wall thereof. Therefore, the motor is free from the operation of closing the through holes that will otherwise be necessary to hermetically seal the stator after assembling the motor so that the overall manufacturing cost of the motor can be reduced.
The above described and other objects and novel feature of the present invention will become apparent more fully from the following specification described in conjunction with the accompanying drawings.
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patent: 4697114 (1987-09-01), Amemiya et al.
patent: 4829657 (1989-05-01), Wright
patent: 4996456 (1991-02-01), Strobl
patent: 5005281 (1991-04-01), Burns
patent: 5040286 (1991-08-01), Stark
patent: 5095611 (1992-03-01), Smith
patent: 5232652 (1993-08-01), Bianco
patent: 5319844 (1994-06-01), Haung et al.
patent: 2 632 788 (1989-12-01), None
patent: 2707813 (1994-07-01), None
patent: 2 707 813 (1995-01-01), None
patent: 5-059661 (1993-03-01), None
Hiruma Hiroshi
Itou Katsutoshi
Uehara Shuji
McCormick Paulding & Huber LLP
Mitsuba Corporation
Smith Sean
Young Lee
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