Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1997-12-30
2000-02-29
Ramirez, Nestor
Electrical generator or motor structure
Dynamoelectric
Rotary
310 40MM, 74421A, 475331, H02K 706, F16H 112, F16H 5708
Patent
active
060313080
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to motors used in geared small machines and equipment such as cameras and printers.
DESCRIPTION OF THE PRIOR ART
A conventional geared motor used in small machines such as cameras forms a small drive mechanism providing a high reduction ratio that comprises a sun gear attached to the free end of the motor shaft and a combination of a stationary and a movable internally-toothed gears, whose numbers of teeth are somewhat different from each other, that are meshed together via a common planetary gear that is in mesh with the sun gear, as disclosed in Japanese Provisional Patent Publication No. 321987 of 1993. Designed to be attached to the free end of the motor, however, this type of drive mechanisms involves a need to further reduce the size of the motor itself to permit use in, for example, cameras of the latest design that employ smaller film cartridges than before.
A drive mechanism disclosed in Japanese Provisional Patent Publication No. 71452 of 1993 offers a solution to the above problem by fastening a stationary internally-toothed gear directly to one end of the casing of a small motor. While possessing an advantage to permit a further reduction in the axial dimension of the motor, this drive mechanism has a problem in that the internally-toothed gear, carrier and other members must be positioned with respect to each other with great accuracy.
Another drive mechanism disclosed in Japanese Provisional Patent Publication No. 88746 of 1988 permits a further reduction in the axial dimension of a geared motor by eliminating a carrier to support a planetary gear and guiding the shaft of a planetary gear by the base of the mechanism and the peripheral wall of a disk provided to a movable internally-toothed gear. However, this drive mechanism cannot give adequate support to the planetary gear. When transmitting a driving force from the stationary internally-toothed gear to the movable internally-toothed gear, as such, the planetary gear tilts to impede the transmission of rotary motion.
An object of this invention that offers a solution to the above problem is to provide a new type of geared motor that permits exact positioning of individual members with respect to each other and a substantial reduction in the axial dimension.
Another object of this invention is to provide a new type of geared motor that permits highly reliable transmission of driving force by supporting the planetary gear in a stable position.
SUMMARY OF THE INVENTION
A geared motor according to this invention comprises a base covering the free end of the shaft of a small motor that has a guide for a rotating carrier supporting a planetary gear and a stationary gear having a guide for a movable gear that are integrally and concentrically formed around a through hole to pass the rotor shaft of the small motor. The geared motor thus designed reduces the axial dimension of the motor itself and accurately positions the individual members thereof.
A geared motor according to this invention also comprises a base covering the free end of the shaft of a small motor and a movable gear that rotates along a guide provided on a stationary gear, each of which having an annular guide that guides a planetary gear to permit the planetary gear to rotate on its own axis and along the guide. The annular guide is formed concentrically around a through hole at the center to pass the rotor shaft of the small motor. At the same time, both sides of the rim of the planetary gear are disposed very close to the facing surfaces of the base and movable gear. This design eliminates the tilting of the planetary gear that otherwise might occur during the transmission of driving force.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view showing a geared motor according to the invention.
FIG. 2 is a perspective view showing the mechanism of a planetary gear used in the same embodiment.
FIG. 3 is a cross-sectional view of another geared motor according to this invention.
PREFERRED EMBODIMENTS OF THE INVE
REFERENCES:
patent: 3707037 (1972-12-01), Gutris
patent: 3774477 (1973-11-01), Murphy
patent: 4680979 (1987-07-01), Morishita et al.
patent: 5452622 (1995-09-01), Fenelon
patent: 5593360 (1997-01-01), Ishida et al.
Kinoshita Satoshi
Sakagami Keisuke
Dinh Le Dang
Ramirez Nestor
Seiko Epson Corporation
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