Planetary gear transmission systems or components – Planetary gearing or element – Coaxial teeth around planet pinion engage axially spaced...
Patent
1990-12-21
1992-12-15
Herrmann, Allan D.
Planetary gear transmission systems or components
Planetary gearing or element
Coaxial teeth around planet pinion engage axially spaced...
74DIG10, 74606R, 475318, 475265, 475902, F16H 132
Patent
active
051711958
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a reduction gear directly joined to a motor, and more particularly is one that relates to the reduction mechanism of a miniature reduction gear of 50 mm maximum diameter that is directly joined to a miniature motor.
FIG. 8 shows an example of a prior miniature reduction gear of this type that uses planetary gears.
In FIG. 8, motor shaft gear 103 is wedged into motor shaft 102 that is in the center of miniature motor 101. Lower case 104 is installed by screw fastening to miniature motor 101 with motor shaft 102 as the central axis. Inner teeth 105 are attached to lower case 104, and there are 2 to 4 planetary gears 106 between them and motor shaft gear 103. Motor shaft gear 103 engages on the inside of plural planetary gears 106, and inner teeth 105 engage on the outside. The centers of plural planetary gears 106 are connected by holder main body 107, and output shaft gear 109 is in the center of holder main body 107. Intermediate cradle 108 is connected to lower case 104, and serves as the bearing for output shaft gear part 109. Output shaft gear 109 engages with planetary gears 106, and planetary gears 106 engage with inner teeth 105. In this manner, the gear that is in the center serves as the motive power, and when we take up to when it rotates holder main body 107 by means of planetary gears 106 as one set, the mechanism repeats the set in any number of stages when the reduction ratio is large. In the final stage of repeating this set, output shaft 110 is in the rotational center of holder main body 107.
Also as shown in FIG. 9, prior miniature reduction gears having a sliding function or a one-way clutch function furnish a sliding mechanism or one-way clutch mechanism on output shaft 110 of miniature reduction gear 121, and transmission is done by transmission gear 123 which is on the said sliding mechanism or one-way clutch mechanism 122.
With such miniature reduction gears using planetary gear mechanisms following the prior constructions shown in FIG. 8 and FIG. 9, the reduction proceeded with holder main body 107 from motor shaft gear 103 via planetary gears 106, but one group of reduction ratios from motor shaft gear 103 to holder main body 107 was small, so it was necessary to have many groups of gears in order to obtain a larger reduction ratio. Because of this, there were problems of cost increases, noise and backlash.
The present invention is one that resolves such prior problems, and its object lies in offering a miniature reduction gear of high transmission efficiency having a miniaturized weight mechanism that takes a sun gear as input and a movable inner gear as output.
SUMMARY OF THE INVENTION
A miniature reduction gear includes a sun gear, a fixed inner gear, a movable inner gear and at least one planetary gear. The planetary gear is formed with three stages of outer teeth that act separately to engage with the sun gear, fixed inner gear and movable inner gear respectively in a reduction mechanism. The sun gear provides an input and the movable inner gear provides an output. The number of planetary gear teeth which engage with the sun gear is greater than the number of teeth which engage with either the fixed inner gear or the movable inner gear.
The planetary gear mechanism of miniature reduction gear of the present invention is supported within a housing and has a sliding function or one-way clutch function, the invention is characterized in having the sliding mechanism or one-way clutch mechanism between the fixed inner gear and the housing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view showing an example of the present invention.
FIG. 2 is a plan view showing an example of the present invention.
FIG. 3 is a sectional view showing an example of a planetary gear used in the miniature reduction gear of the present invention.
FIG. 4 is a sectional view showing an example of an output shaft embodied in a movable internal gear used in the miniature reduction gear of the present invention.
FIG. 5 is a section
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Herrmann Allan D.
Seiko Epson Corporation
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