U.S. patent application number 09/785280 was filed with the patent office on 2002-10-03 for drum-type motor with inner gear.
Invention is credited to Hsu, Chun-pu.
Application Number | 20020140302 09/785280 |
Document ID | / |
Family ID | 26076481 |
Filed Date | 2002-10-03 |
United States Patent
Application |
20020140302 |
Kind Code |
A1 |
Hsu, Chun-pu |
October 3, 2002 |
DRUM-TYPE MOTOR WITH INNER GEAR
Abstract
A drum-type motor combines planet gear and spindle motor. The
planet gear is arranged on lateral side of the spindle motor and
the axis of the spindle motor is functioned as sun gear. The
drum-type motor of the present invention has an inner gear engaged
with the planet gear. The inner gear and the sun gear have such
tooth ratio that the drum-type motor of the present invention has
high torque at low rotation speed.
Inventors: |
Hsu, Chun-pu; (Taipei Hsien,
TW) |
Correspondence
Address: |
ROSENBERG, KLEIN & LEE
3458 ELLICOTT CENTER DRIVE-SUITE 101
ELLICOTT CITY
MD
21043
US
|
Family ID: |
26076481 |
Appl. No.: |
09/785280 |
Filed: |
February 20, 2001 |
Current U.S.
Class: |
310/75R ; 310/80;
310/83 |
Current CPC
Class: |
B62M 6/65 20130101; H02K
7/116 20130101 |
Class at
Publication: |
310/75.00R ;
310/83; 310/80 |
International
Class: |
H02K 007/116 |
Claims
I claim
1. A drum-type motor with inner gear, comprising a spindle motor
having two lateral sides, and a spin axis provided on each lateral
side thereof and functioning as a sun gear; the spindle motor
having at least concentric fixing part on each lateral side
thereof; a planet gear set composed of a plurality of planet gears;
one side of the planet gear fixed to one concentric fixing part;
another side of the gear having an outward extended circular bump,
which is concentrically engaged to the inner surface of a rotation
bearing; the circular bump having an outward extended supporting
shaft, which provides support for the drum-type motor; the sun gear
passed through the center of the planet gear set and the sun gear
engaged with the planet gears; the drum-type motor having a lateral
side with an inner concave circle and an outer concave circle
concentric to the inner concave circle; the drum-type motor having
an inner gear concentrically fixed within the outer concave circle
and the inner concave circle housing the outer circle of the
rotation bearing such that the inner gear is engaged to the outer
tooth of the planet gear, thus magnifying the torque provided by
the spindle motor through the sun gear.
2. The drum-type motor with inner gear as in claim 1, wherein both
sides of the spindle motor have extruding axes extruding from the
spindle to function as the sun gears; the sun gears engaged to the
teeth of the planet gear sets on the two lateral sides; the planet
gear sets on the two lateral sides engaged to the inner gear; the
torque of the spindle motor magnified through the tooth ratio of
the sun gear and the inner gear; the inner gear driving a drum
shell of the drum-type motor to output the torque.
3. The drum-type motor with inner gear as in claim 1, wherein one
side of the spindle motor has an extruding axis extruding from the
spindle to function as the sun gear; the sun gear engaged to the
teeth of the planet gear sets on one lateral side; the planet gear
engaged to the inner gear; the torque of the spindle motor
magnified through the tooth ratio of the sun gear and the inner
gear; the inner gear driving a drum shell of the drum-type motor to
output the torque.
4. The drum-type motor with inner gear as in claim 1, wherein the
planet gear of the planet gear set is clamped by a side plate to
the lateral side of the spindle motor.
5. The drum-type motor with inner gear as in claim 1, wherein for
the planet gear without side plate, the planet gear of the planet
gear set is clamped by circular hole on the lateral side.
6. The drum-type motor with inner gear as in claim 1, wherein the
extruding axis of the motor is directly lathed to form the sun
gear.
7. The drum-type motor with inner gear as in claim 1, wherein the
axis of the motor is separately formed and assembled to the center
of the sun gear.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a drum-type motor,
especially to a drum-type motor with inner gear, which has high
efficiency and provides high torque output at low rotation
speed
BACKGROUND OF THE INVENTION
[0002] The conventional outer-rotor drum-type motor 51, as shown in
FIG. 7, comprises a stator 511, an outer rotor magnet 512, a magnet
shell 513, two side plates 514, a spindle 315 and a motor casing
415. In this conventional outer-rotor drum-type motor 51, the drum
of the motor is directly driven by the outer rotor for operation.
However, when the drum-type motor is operated in low rotation speed
condition such as electrical bicycle, the motor output power of the
motor is proportional to the motor rotation speed with reference to
the formula:
T=P/N=A.multidot.B.multidot.L.multidot.D.sup.2.multidot.6.1.times.10.sup.8
[0003] Wherein
1 T: motor torque (N/cm) P: output power (Watt) N: motor rotation
speed (rpm) A: current density (Amp/cm) B: magnetic flux density L:
length of rotor (cm) D: outer radius of rotor (cm)
[0004] As can be seen from above formula, the power (P) of the
motor is low when the motor is operated at low rotation speed and
fixed outer rotor radius. To increase the motor output power at low
rotor rotation speed, the current density (A) and the magnetic flux
density (B) should be increased. However, this imposes a serious
problem to the mechanical structure of the motor. To increase the
current density (A), the thickness and turn number of the coils
should be increased. However, the coils generally occupy a specific
area ration on the winding groove of the rotor.
[0005] To overcome above problems, the present invention provides a
drum-type motor combining planet gear and spindle motor. The planet
gear is arranged on lateral side of the spindle motor and the axis
of the spindle motor is functioned as sun gear. The drum-type motor
of the present invention has an inner gear engaged with the planet
gear. The inner gear and the sun gear have such tooth ratio that
the drum-type motor of the present invention has high torque at low
rotation speed.
SUMMARY OF THE INVENTION
[0006] The present invention is intended to provide a drum-type
motor, which has high efficiency and provides high torque output at
low rotation speed. The dissipated power of the motor is as
follow:
W=I.sup.2R
[0007] W: dissipated power of the motor (Watt)
[0008] I: current (Amp)
[0009] R: copper resistance of coil (.OMEGA.)
[0010] As can be seen from above formula, the output power of the
motor depends on the operation current (I) and the copper
resistance (.OMEGA.) of coil. If the motor can provide sufficient
torque at low operation current (I), the motor should have low
copper resistance of coil and high operational efficiency.
Therefore, the drum-type motor is designed to operate at low
rotation speed and high torque with high rotation speed and high
efficiency.
[0011] The various objects and advantages of the present invention
will be more readily understood from the following detailed
description when read in conjunction with the appended drawing, in
which:
BRIEF DESCRIPTION OF DRAWING
[0012] FIG. 1 is the exploded view of the first preferred
embodiment of the invention;
[0013] FIG. 2 is the exploded view of the first preferred
embodiment of the invention, wherein the planet gear set has side
plate;
[0014] FIG. 3 is the exploded view of the first preferred
embodiment of the invention, wherein the planet gear set has not
side plate;
[0015] FIG. 4 is the perspective view of the first preferred
embodiment of the invention;
[0016] FIG. 4A is the sectional view of the first preferred
embodiment of the invention;
[0017] FIG. 5 is the exploded view of the second preferred
embodiment of the invention;
[0018] FIG. 6 is the perspective view of the second preferred
embodiment of the invention;
[0019] FIG. 6A is the sectional view of the second preferred
embodiment of the invention;
[0020] FIG. 7 is the exploded view of prior art outer-rotor
drum-type motor.
DETAILED DESCRIPTION OF THE INVENTION
[0021] With reference now to FIGS. 1 to 6, the drum-type motor 10
of the present invention comprises a spindle motor 21. The spindle
motor 21 has a torque-outputting shaft on one lateral side thereof
and is functioned as a sun gear 213 of the drum-type motor 10. The
spindle motor 21 has two lateral sides 211 each having at least one
concentric fixing end 212. The drum-type motor 10 of the present
invention further comprises a planet gear set composed a plurality
of gears 312. The center of each planet gear 312 has a motor-signal
guiding hole 214. One side of the gear 312 is concentrically
arranged on the concentric fixing end 212, another side of the gear
312 has an outward extended circular bump 316 with a circular plate
314. The outward extended circular bump 316 is concentrically
engaged to the inner surface of a rotation bearing 412. The outward
extended circular bump 316 further has an outward extended
supporting shaft 315, which provides support for the drum-type
motor 10. The sun gear 213 is passed through the center of the
planet gear set. The drum-type motor 10 has lateral side 41 with an
inner concave circle 414 and an outer concave circle 413 concentric
to the inner concave circle 414. The drum-type motor 10 has an
inner gear 411 concentrically fixed within the outer concave circle
413 and the inner concave circle 414 housing the outer circle of
the rotation bearing 412. The inner gear 411 is engaged to the
outer tooth of the planet gear 312, thus magnifying the torque
provided by the spindle motor 21 through the sun gear 213.
[0022] Both sides 211 of the spindle motor 21 have extruding axes
extruding from the spindle to function as the sun gears 213. The
sun gears 213 are engaged to the teeth of the planet gear sets on
the two lateral sides 211. The planet gear sets on the two lateral
sides 211 are engaged to the inner gear 411. The torque of the
spindle motor 21 is magnified through the tooth ratio of the sun
gear 213 and the inner gear 411. Afterward, the inner gear 411
drives the drum shell 415 to output the torque.
[0023] As shown in FIGS. 5, 6 and 6A, the spindle motor 21 has only
one axis extruding from one lateral side 211 thereof and functioned
as sun gear 213. The sun gear 213 is engaged to the tooth of the
planet gear set on the lateral side 211. The planet gear set on the
lateral side 211 is engaged to the inner gear 411. The torque of
the spindle motor 21 is magnified through the tooth ratio of the
sun gear 213 and the inner gear 411. Afterward, the inner gear 411
drives the drum shell 415 to output the torque.
[0024] As shown in FIGS. 1 and 2, the planet gear 312 of the planet
gear set 32 is clamped by a side plate 313 to the lateral side 211
of the spindle motor 21, The side plate 313 is screwed by screws
317 to the lateral side 211.
[0025] As shown in FIG. 3, when the planet gear set 311 has no side
plate, the planet gear 312 of the planet gear set 311 is clamped by
circular hole 215 on the lateral side 211.
[0026] The extruding axis of the motor 21 can be directly lathed to
form the sun gear 213, alternatively the spin axis of the motor 21
can be separately formed and assembled to the center of the sun
gear 213.
[0027] Although the present invention has been described with
reference to the preferred embodiment thereof, it will be
understood that the invention is not limited to the details
thereof. Various substitutions and modifications have suggested in
the foregoing description, and other will occur to those of
ordinary skill in the art. Therefore, all such substitutions and
modifications are intended to be embraced within the scope of the
invention as defined in the appended claims.
* * * * *