Speed reducer in a portable electric tool

Details Speed reducer in a portable electric tool Speed reducer in a portable electric tool

2001-02-28

2002-10-01

Marmor, Charles A (Department: 3722)

Planetary gear transmission systems or components

Planetary gearing or element

C475S335000, C074S415000

Reexamination Certificate

active

06458058

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a speed reducer in a portable electric tool, and particularly to a speed reducer in a portable electric tool for automotive repair, which can increase the torque and prolong the life span in use.
2. Description of Related Art
Referring to
FIG. 1
, a latest developed portable electric tool is illustrated. The portable electric tool comprises a primary handle
10
and a gearbox on the primary handle. The gearbox is composed of a front casing
21
and a rear casing
22
and a first spacing block
23
and a second spacing black
24
are disposed between the front casing
21
and the rear casing
22
.
A motor
30
is fixedly attached to the rear casing
22
and the motor preferably is 12V direct current type for being carried about with the car. A spindle
31
of motor
30
can be inserted between the rear casing
22
and the first spacing block
23
. The free end of the spindle
31
provides a motor gear
32
and a first planetary gear set
40
is rotationally provided between the rear casing
22
and the first spacing block
23
. The first planetary gear set
40
provides planetary gears
41
,
42
,
43
surrounding and meshing with the motor gear
32
. The respective planetary gears
41
,
42
,
43
has teeth more than that on the motor gear
32
so as to constitute a first stage of speed reduction. A respective secondary planetary gear
410
,
420
,
430
is fixed to a respective shaft same as the planetary gears
41
,
42
,
43
to mesh with a transmission gear
44
for second stage of speed reduction. The transmission gear
44
provides a middle shaft
45
extends through the first spacing block
23
and a driven gear
46
is attached to the middle shaft between the first and the second spacing blocks
23
,
24
.
A second planetary gear set
50
is arranged between the first and the second spacing blocks
23
,
24
and has planetary gears
51
,
52
,
53
thereon to surround and mesh with the driven gear
46
. The planetary gears
51
,
52
,
53
each provide a pitch diameter and teeth smaller than the driven gear
46
so as to constitute a third stage of speed reduction. Each planetary gear
41
,
42
,
43
provides a shaft and the respective shaft further has a corresponding secondary gear
510
,
520
,
530
with a pitch diameter and teeth smaller than the planetary gear
51
,
52
,
53
. A transmission gear
54
is surrounded by and meshing with the secondary gears
510
,
520
,
530
to constitute a fourth stage of speed reduction. An axial shaft
55
provided on the transmission gear
54
passes through the second spacing block
24
such that a driven gear
56
is arranged on the axial shaft between the second spacing block
24
and the front casing
21
.
A third planetary gear set
60
is arranged between the second spacing block
24
and the front casing
21
and has planetary gears
61
,
62
,
63
surrounding and meshing with the driven gear
56
. The teeth and the pitch diameter of respective planetary gear
61
,
62
,
63
are greater than the driven gear
56
to constitute a fifth stage of speed reduction. Each planetary gear
61
,
62
,
63
provides a shaft and the respective shaft further has a corresponding secondary gear
610
,
620
,
630
with teeth smaller than the planetary gear
61
,
62
,
63
. An output gear
71
is surrounded and meshes with the secondary gears
610
,
620
,
630
to constitute a sixth stage of speed reduction. The output gear
71
has an output shaft
72
extends outward the front casing
21
so that an outer end of the output shaft
72
with an engaging head
73
can fit with sleeve for fastening or loosening bolts or nuts.
The torque provided by the prior art is somewhat insufficient from the point of view with regard to the entire structure of speed reducer thereof. Nevertheless, the most serious disadvantage of the prior art is that the third planetary gear set is easily damaged, and it is the reason that planetary gears
61
,
62
,
63
are apt to warp outward and become deformed during subjecting the resistant force of output gear
71
. Hence, it may occur a problem of planetary gears
61
,
62
,
63
being in a state of loosening or occur a phenomenon of the output gear
71
or planetary gears
61
,
62
,
63
becoming slippery during meshing to each other and resulting in a situation of gear fracture. Hence, these defects resided in the prior art have to be overcome from the design of structure.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide a speed reducer in a portable electric tool, with which an output internal gear with internal circular teeth are arranged to mesh with over pins instead of planetary gears directly. Thus, the output torque can be enhanced and the phenomenon of gear damage or gear loosening can be avoided substantially.


REFERENCES:
patent: 1970251 (1934-08-01), Rossman
patent: 3587348 (1971-06-01), Enoiu
patent: 3661028 (1972-05-01), Fuchs
patent: 4699023 (1987-10-01), Bajulaz
patent: 5098358 (1992-03-01), Igaku
patent: 149799 (1937-01-01), None

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