U.S. patent application number 16/114250 was filed with the patent office on 2019-12-26 for transmission system and electric tool provided with same.
The applicant listed for this patent is Zhejiang Minglei Tools Industry Co., LTD.. Invention is credited to Zhi Ouyang, Lei Weng.
Application Number | 20190389047 16/114250 |
Document ID | / |
Family ID | 63691871 |
Filed Date | 2019-12-26 |
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United States Patent
Application |
20190389047 |
Kind Code |
A1 |
Weng; Lei ; et al. |
December 26, 2019 |
TRANSMISSION SYSTEM AND ELECTRIC TOOL PROVIDED WITH SAME
Abstract
Provided herein is a transmission system including: a housing; a
pair of double-layered gears for transmitting a power from a motor
to a screw driver shaft defining a transmission axis, the pair of
gears including a first bigger gear and a first smaller gear; a
torque cup for covering a leading end portion of the housing
through which the shaft is extended from the housing; a first set
of planetary gears for driving the shaft, regularly surrounding and
meshing the first smaller gear; and a first ring gear for sliding
axially against the housing and meshing the first bigger gear
and/or the first set of planetary gears; wherein the torque cup can
be turned to force the first ring gear to slide axially.
Inventors: |
Weng; Lei; (Ningbo, CN)
; Ouyang; Zhi; (Ningbo, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Zhejiang Minglei Tools Industry Co., LTD. |
Ningbo |
|
CN |
|
|
Family ID: |
63691871 |
Appl. No.: |
16/114250 |
Filed: |
August 28, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F16H 2200/2064 20130101;
F16H 2200/2007 20130101; F16H 1/2818 20130101; F16H 2200/2035
20130101; F16H 2200/2033 20130101; F16H 3/56 20130101; F16H 57/023
20130101; F16H 2200/2097 20130101; F16H 61/686 20130101; B25F 5/001
20130101; F16H 2200/2094 20130101; F16H 35/10 20130101; F16H 3/72
20130101; F16H 3/54 20130101; F16H 2200/0034 20130101 |
International
Class: |
B25F 5/00 20060101
B25F005/00; F16H 61/686 20060101 F16H061/686; F16H 3/56 20060101
F16H003/56; F16H 1/28 20060101 F16H001/28; F16H 3/72 20060101
F16H003/72; F16H 57/023 20060101 F16H057/023 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 2018 |
CN |
201810646354.1 |
Claims
1. A transmission system, comprising: a housing (1); a
double-layered gears (4) for transmitting a power from a motor to a
mounting shaft (14) for clasping a screw driver bit or a drill bit
and defining a transmission axis, the double-layered gears (4)
comprising a first outer or bigger gear (4a) and a first inner or
smaller gear (4b); a torque cup (9) mounted to the housing to cover
an leading end portion of the housing through which the mounting
shaft is extended partially outside the housing ; a first set of
planetary gears (5) for driving the mounting shaft,
circumferentially regularly surrounding and meshing the first inner
gear (4b), a first ring gear (6) fixed circumferentially and
relatively to the housing so that it can slide axially to mesh both
of the first outer gear (4a) and the first set of planetary gears
(5) or only the former; wherein the torque cup (9) is configured so
that it can be turned to force the first ring gear (6) to slide
axially.
2. The transmission system according to claim 1, wherein the first
ring gear (6) is surrounded with a gear sleeve (7), and the gear
sleeve (7) and the first ring gear (6) are axially locked; and the
torque cup can be turned to force the gear sleeve (7) to slide
axially.
3. The transmission system according to claim 1, further
comprising: a sun gear (10) rotatable around the transmission axis
and having an axial end fixed with a plurality of axial stubs each
of which co-axially supports one of the first set of planetary
gears (5) for rotation around itself; and a second set of planetary
gears (11) for driving the mounting shaft (14), meshing inwards
with the sun gear (10) and outwards with a second ring gear (12),
which is mounted to the housing for a rotation restrained with
respect to the housing.
4. The transmission system according to claim 2, further
comprising: a sun gear (10) rotatable around the transmission axis
and having an axial end fixed with a plurality of axial stubs each
of which co-axially supports one of the first set of planetary
gears (5) for rotation around itself; and a second set of planetary
gears (11) for driving the mounting shaft (14), meshing inwards
with the sun gear (10) and outwards with a second ring gear (12),
which is mounted to the housing for a rotation restrained with
respect to the housing.
5. The transmission system according to claim 4, wherein the second
ring gear is provided with an axial and endless profile or cam
which is urged against the housing.
6. An electric tool comprising a transmission system according to
claim 1.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application claims priority of Chinese Patent
Application No. 201810646354.1, filed on Jun. 21, 2018 in the State
Intellectual Property Office of China, the entire contents of which
are hereby incorporated by reference.
TECHNICAL FIELD
[0002] The invention relates to an electric tool, in particular to
a transmission system and an electric tool provided with same.
BACKGROUND ART
[0003] Transmission system is one of the main core components of an
electric tool, and its main function is to provide the power needed
for the electric tool to rotate. Existing electric tools all have
multiple functions for the convenience of use, that is, they can be
used for drilling and screwing at the same time.
[0004] In order to realize the above-mentioned operation functions,
enterprises also make some structural improvements to the
transmission system during transmission system production, i.e. the
transmission system is equipped with a speed change mechanism and a
torque cup at the same time, so as to switch between various
functions.
[0005] For example, the Chinese patent application number
201120271287.3 discloses an improved structure for high-speed and
low-speed switch of an electric tool, and a shift lever of the
improved structure is driven by a shift frame which is directly
exposed outside a transmission system housing for operation by
workers. In this way, workers are likely to come into contact with
the shift frame unintentionally during operation, thus increasing
the probability of misoperation. When the electric tool works under
the condition of large torque, if the rotating speed increases
instantaneously, it is easy to cause damage to a transmission
shaft.
SUMMARY OF THE INVENTION
[0006] Therefore, the invention provides A transmission system,
comprising: [0007] a housing; [0008] a pair of double-layered gears
for transmitting a power from a motor to a mounting shaft for
clasping a screw driver bit or a drill bit and defining a
transmission axis, the pair of double-layer gear comprising a first
outer or bigger gear and a first inner or smaller gear; [0009] a
torque cup mounted to the housing to cover an leading end portion
of the housing through which the mounting shaft is extended
partially outside the housing ; [0010] a first set of planetary
gears for driving the mounting shaft, circumferentially regularly
surrounding and meshing the first inner gear, [0011] a first ring
gear fixed circumferentially and relatively to the housing so that
it can slide axially to mesh both of the first outer gear and the
first set of planetary gears or only the former; [0012] wherein the
torque cup is configured so that it can be turned to force the
first ring gear to slide axially.
[0013] Preferably, the first ring gear is surrounded with a gear
sleeve, and the gear sleeve and the first ring gear are axially
locked; and the torque cup can be turned to force the gear sleeve
to slide axially.
[0014] Preferably, the transmission system further comprises:
[0015] a sun gear ratatable around the transmission axis and having
an axial end fixed with a plurality of axial stubs each of which
co-axially supports one of the first set of planetary gears for
rotation around itself; and [0016] a second set of planetary gears
for driving the mounting shaft, meshing inwards with the sun gear
and outwards with a second ring gear, which is mounted to the
housing for a rotation restrained with respect to the housing.
[0017] Most preferably, the second ring gear is provided with an
axial and endless profile or cam which is urged against the
housing.
[0018] The invention relates also to an electric tool comprising
such a transmission system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic structural diagram of a transmission
system according to embodiment 1;
[0020] FIG. 2 is a first explosive view of the transmission system
according to embodiment 1;
[0021] FIG. 3 is a second explosive view of the transmission system
according to embodiment 1;
[0022] FIG. 4 is a third explosive view of the transmission system
according to embodiment 1;
[0023] FIG. 5 is a partial schematic structural diagram of the
transmission system according to embodiment 1;
[0024] FIG. 6 is a fourth explosive view of the transmission system
according to embodiment 1;
[0025] FIG. 7 is a fifth explosive view of the transmission system
according to embodiment 1;
[0026] FIG. 8 is a sixth explosive view of the transmission system
according to embodiment 1;
[0027] FIG. 9 is a seventh explosive view of the transmission
system according to embodiment 1;
[0028] FIG. 10 is an enlarged view of a part A of FIG. 9;
[0029] FIG. 11 is a structural view of a torque cup and a lifting
pin of embodiment 2;
[0030] FIG. 12 is a structural view of a torque cup and a lifting
pin of embodiment 3;
[0031] FIG. 13 is a partial schematic structural diagram of a
transmission system according to embodiment 4;
[0032] FIG. 14 is a sectional view of the transmission system
according to embodiment 4.
[0033] Reference Numerals: 1. housing; 1a. front housing body; 1a1.
guide hole; 1a2. second limiting block; 1b. rear housing body; 1b1.
first blind hole; 1c. bottom cover; 1c1. through hole; 1d. front
cover; 1d1. limiting hole; 2. second planetary gear set; 3. second
inner gear; 4. double-layer gear; 4a. first outer ring gear; 4b.
first inner ring gear; 5. first planetary gear set; 6. first inner
gear; 7. gear sleeve; 7a. fixing block; 7b. lifting pin; 7b1:
spherical surface; 7b2: tapered; 7c. biasing spring; 8a. lug; 8b.
sliding groove; 9. torque cup; 9a. inner edge; 9b. protrusion; 9b1.
concave cambered surface; 9b2. tapered groove; 9c. steel ball; 9d.
second extension spring; 9e. second blind hole; 10. sun gear; 10a.
disc; 10b. second inner ring gear; 11. third planetary gear set;
12. third inner gear; 12a. projection; 13. transmission ring; 13a.
first limiting block; 14. mounting shaft; 15. shaft sleeve; 15a.
clamping block; 16. thread bushing; 16a. first spring; 17. torque
washer ; 17a. teeth; 17b. lifting rod; 17c. ball.
DETAILED DESCRIPTION OF THE INVENTION
[0034] The invention will be described in further detail below with
reference to the accompanying drawings.
Embodiment 1
[0035] A transmission system, as shown in FIG. 1 and FIG. 2,
comprises a housing 1 which is divided into a front housing body 1a
and a rear housing body 1b, the rear portion of the rear housing
body 1b is provided with a bottom cover 1c, and the center of the
bottom cover 1c is provided with a through hole 1c1 through which
an output shaft of a motor can pass. The rear housing body 1b is
internally provided with a second planetary gear set 2 which is
attached to the bottom cover 1c, and planetary gears of the second
planetary gear set 2 are uniformly distributed around the through
hole 1c1 and can mesh with the output shaft of the motor. The
number of the planetary gears in the second planetary gear set 2
can be selected according to the actual situation, and here it is
three. In addition, the second planetary gear set 2 is further
sleeved with a second inner gear 3, and the second inner gear 3 is
fixed to the rear housing body 1b.
[0036] Furthermore, as shown in FIG. 3, the rear housing body 1b is
further provided with a double-layer gear 4 inside. Shafts of the
planetary gears of the second planetary gear set 2 are fixed to a
first outer ring gear 4a of the double-layer gear 4 and are also
uniformly distributed around the center of the double-layer gear 4.
While a first inner ring gear 4b of the double-layer gear 4 is
located on the side, away from the second planetary gear set 2, of
the first outer ring gear 4a. Here, the center of the double-layer
gear 4 is coaxial with the through hole 1c1.
[0037] Besides, as shown in FIG. 4, a first planetary gear set 5 is
evenly distributed around the first inner ring gear 14b, and the
first planetary gear set 5 can indirectly drive a mounting shaft 14
for mounting a drill bit or a screwdriver. Also, each planet gear
of the first planetary gear set 5 meshes with the first inner ring
gear 4b. At the same time, the first planetary gear set 5 and the
first outer ring gear 4a are sleeved with a same first inner gear
6, and the first inner gear 6 can slide between the first planetary
gear set 5 and the first outer ring gear 4a.
[0038] In addition, as shown in FIG. 4 and FIG. 5, there is a
locking structure between the outer peripheral surface of the first
inner gear 6 and the inner side of the front housing body 1a, and
the locking structure mainly comprises a plurality of lugs 8a
evenly distributed on the peripheral surface of the first inner
gear 6 and sliding groove 8b located on the inner side of the front
housing body 1a and matched with the lugs 8a. When the first inner
gear 6 is completely sleeved outside the first planetary gear set
5, the lugs 8a can be inserted into the sliding groove 8b, thus
realizing the locking between the first inner gear 6 and the
housing 1. When the first inner gear 6 is sleeved on the first
planetary gear set 5 and the first outer ring gear 4a at the same
time, the lugs 8a disengage from the sliding groove 8b, thus
realizing the unlocking between the first inner gear 6 and the
front housing body 1a. In addition, the first inner gear 6 is also
sleeved with a gear sleeve 7. Here, the first inner gear 6 and the
gear sleeve 7 are fixed in the axial direction, while the first
inner gear 6 can rotate in the circumferential direction. When the
first inner gear 6 is completely sleeved on the first planetary
gear set 5, the first planetary gear set 5 rotates on its axis and
revolves around the first inner ring gear 4b, at this point, the
revolution angular velocity of the first planetary gear set 5 is
smaller than the rotation angular velocity of the double-layer gear
4. When the first inner gear 6 is sleeved outside the first
planetary gear set 5 and the first outer ring gear 4a at the same
time, the first inner gear 6, the double-layer gear 4 and the first
planetary gear set 5 are locked, at this point, the first planetary
gear set 5 only revolves. At this point, the revolution angular
velocity of the first planetary gear set 5 is equal to the rotation
angular velocity of the double-layer gear 4. In this way, speed
change of the transmission system can be realized by the sliding
switch of the first inner gear 6 between the first planetary gear
set 5 and the first outer ring gear 4a.
[0039] Meanwhile, as shown in FIG. 6, the outer peripheral surface
of the gear sleeve 7 is provided with fixing blocks 7a, and the
number of the fixing blocks 7a can be determined according to the
actual situation. Here, the number of the fixing blocks 7a is two,
and the fixing blocks 7a are evenly distributed around the center
of the gear sleeve 7. Each fixing block 7a is provided with a
lifting pin 7b, and the lifting pin 7b, the fixing block 7a and the
gear sleeve 7 are integrally formed. In addition, the lifting pins
7b are arranged parallel to the axial direction of the gear sleeve
7. The end, facing the bottom cover 1c, of each lifting pin 7b is
further sleeved with a biasing spring 7c, and one end of each
biasing spring 7c abuts against the corresponding fixing block 7a.
In addition, the outer peripheral surface of the rear housing body
1b is provided with first blind holes 1b1, and the other end of
each biasing spring 7c abuts against the bottom of the
corresponding first blind hole 1b1. In this way, on the one hand,
the biasing springs 7c can support the lifting pins 7b, which is
conducive to keeping the stress on the lifting pins 7b in balance,
on the other hand, the first blind holes 1b1 can also limit the
biasing springs 7c, thus reducing the damage caused by the torsion
of the biasing springs 7c during stretching. Moreover, the outer
peripheral surface of the front housing body 1a is also provided
with guide holes 1a1, and the lifting pins 7b are inserted into the
guide holes 1a1 and can slide in the guide holes 1a1. Thus, the
guide holes 1a1 can protect the lifting pins 7b and guide the
lifting pins 7b to slide in an accurate direction.
[0040] Furthermore, the side, away from the bottom cover 1c, of the
front housing body 1a is also provided with a torque cup 9, and the
inner peripheral surface of the torque cup 9 is provided with an
inner edge 9a. The inner edge 9a is provided with protrusions 9b
corresponding to the lifting pins 7b, and the transition between
the protrusions 9b and the inner edge 9a is continuous and natural.
When the torque cup 9 is rotated till the protrusions 9b come into
contact with the ends of the lifting pins 7b, the protrusions 9b
start to push the lifting pins 7b by continuing to rotate the
torque cup 9. Accordingly, the lifting pins 7b slide toward the
side of the bottom cover 1c and drive the first inner gear 6 to
slide to the position where the first inner gear 6 is
simultaneously sleeved on the first outer ring gear 4a and the
first planetary gear set 5. This also realizes the process of
controlling the speed increase of the transmission system through
the torque cup 9. Furthermore, when the torque cup 9 is rotated
reversely, the acting force of the protrusions 9b on the lifting
pins 7b will be removed, so that the lifting pins 7b can reset
under the action of the biasing springs 7c, thus realizing the
speed decrease of the transmission system.
[0041] In addition, as shown in FIG. 7, the front housing body 1a
is internally provided with a sun gear 10 which is composed of a
disk 10a and a second inner ring gear 10b coaxial with the disk
10a. Here, shafts of the planetary gears of the first planetary
gear set 5 are all arranged on the side, away from the second inner
ring gear 10b, of the disc 10a in a inserting mode, and the
planetary gears are evenly distributed around the center of the sun
gear 10. A third planetary gear set 11 is evenly distributed around
the second inner ring gear 10b, and each planetary gear of the
third planetary gear set 11 meshes with the second inner ring gear
10b. In addition, the third planetary gear set 11 is sleeved with a
third inner gear 12 which meshes with each planetary gear of the
third planetary gear set 11.
[0042] As shown in FIG. 8, shafts of the planetary gears of the
third planetary gear set 11 are uniformly distributed around the
center of a transmission ring 13 in the circumferential direction
and are arranged on the transmission ring 13 in a penetrating mode,
and the transmission ring 13 is coaxial with the through hole 1c1.
First limiting blocks 13a are evenly distributed on the side, away
from the third planetary gear set 11, of the transmission ring 13.
The end of the mounting shaft 14 is provided with a shaft sleeve
15, the mounting shaft 14 and the shaft sleeve 15 are locked in the
circumferential direction, that is, the end of the mounting shaft
is hexagonal, the inner ring of the shaft sleeve is also hexagonal,
and the two are matched with each other. The circumferential
surface of the shaft sleeve 15 is provided with clamping blocks 15a
matched with the first limiting blocks 13a, and the clamping blocks
15a can be embedded between two adjacent first limiting blocks 13a,
so that the transmission ring 13, the sleeve 15 and the mounting
shaft 14 are relatively stationary.
[0043] As shown in FIG. 9, the mounting shaft 14 extends into the
front housing body 1a and is fixed in the front housing body 1a
through two bearings. In addition, the front housing body 1a is
sleeved with a thread bushing 16 on the outer peripheral surface
where the mounting shaft 14 is located. Here, the outer side of the
thread bushing 16 is matched with the inner side of the torque cup
9 through threads. The front housing body 1a is further sleeved
with a torque washer 17 at the side end, facing the bottom cover
1c, of the thread bushing 16. Here, the inner ring of the torque
washer 17 is provided with teeth 17a, and the front housing body 1a
is provided with second limiting blocks 1a2 on the inner side of
the thread bushing 16. The second limiting blocks 1a2 are evenly
distributed along the axial center of the front housing body 1a,
and the second limiting blocks 1a2 are arranged along the axial
direction of the mounting shaft 14. The second limiting blocks 1a2
can just pass through the space between two adjacent teeth 17a. At
the same time, lifting rods 17b are evenly distributed in the
circumferential direction on the side, facing the bottom cover 1c,
of the torque washer 17, one end of each lifting rod 17b is fixed
to the torque washer 17, and the other end of each lifting rod 17b
abuts against the surface of the third inner gear 12. In addition,
the lifting rods 17b extends into the front housing body 1a.
[0044] In addition, as shown in FIG. 9 and FIG. 10, first extension
springs 16a are arranged between the inner side of the thread
bushing 16 and the outer side of the front housing body 1a. One end
of each first extension spring 16a abuts against the bottom of the
thread bushing 16, and the other end abuts against the torque
washer 17. The side, away from the thread bushing 16, of the bottom
of the torque cup 9 is provided with a front cover 1d which is
fixed to the front housing body 1a through a bolt. In addition, a
plurality of limiting holes 1d1 are distributed around the center
of the front cover 1d, and the number of the limiting holes 1d1 can
be set according to the actual situation. The side, facing the
front cover 1d, of the torque cup 9 is provided with steel balls 9c
matched with the limiting holes 1d1. The number of the steel balls
9c can be determined according to the actual situation, and the
steel balls 9c are symmetrical about the axial center of the torque
cup 9. In addition, the steel balls 9c abut against the bottom of
the torque cup 9 through second extension springs 9d, and the
bottom of the torque cup 9 is provided with second blind holes 9e.
Each second extension spring 9d abuts against the bottom of the
corresponding second blind hole 9e. Through the interference fit
between the steel balls 9c and the different limiting holes 1d1,
workers can select different gear positions conveniently.
[0045] Working principle of the transmission system: based on
low-speed operation, the output shaft of the motor first drives the
second planetary gear set 2 through gears to rotate on its axis and
revolve at the same time. Since the shafts of the planetary gears
of the second planetary gear set 2 are fixed to a first outer ring
gear 4a of the double-layer gear 4, the second planetary gear set 2
will drive the double-layer gear 4 to rotate on its axis. When the
double-layer gear 4 rotates on its axis, the first inner ring gear
4b will drive the first planetary gear set 5 to rotate on its axis
and revolve. Since the first planetary gear set 5 is arranged on
the sun gear 10 in a penetrating mode, the first planetary gear set
15 will drive the sun gear 10 to rotate on its axis. The second
inner ring gear 10b of the sun gear 10 will drive the third
planetary gear set 11 to rotate on its axis and revolve. Since the
third planetary gear set 11 is arranged on the transmission ring 13
in a penetrating mode, the transmission ring 13 will be driven to
rotate on its axis, so as to drive the mounting shaft 14 to rotate
on its axis through the shaft sleeve 15. Due to the low-speed
state, a screwdriver bit can be installed at the end of the
mounting shaft 14 to screw bolts or screws.
[0046] Torque adjustment: in order to increase the torque of
screwing, workers can screw the torque cup 9, and the thread
bushing 16 will move toward the side of the bottom cover 1c under
the action of the screw of the torque cup 9, so that the thread
bushing 16 will compress the first extension springs 16a. Then the
first extension springs 16a exert pressure on the torque washer 17,
and the torque washer 17 exerts pressure on third inner gear 12
through the lifting rods 17b. When the first extension springs 16a
are pressed more tightly, the third inner gear 12 will be more
fixed firmly, and thus the torque will be greater.
[0047] Speed increasing process of the transmission system: when
the torque cup 9 is reversely screwed, the pressure of the thread
bushing 16 putting on the first extension springs 16a will
decrease, and the protrusions 9b on the inner edge 9a will
gradually make contact with the ends of the lifting pins 7b; when
the protrusions 9b push the lifting pins 7b, the torque of the
transmission system is the smallest, at this point, the lifting
pins 7b will push the first inner gear 6 to move till the first
inner gear 6 is directly sleeved on the first planetary gear set
and the first outer ring gear 4a, so that the first planetary gear
set, the first outer ring gear 4a and the first inner gear 6 are
locked. At this point, the rotation angular velocity of the
double-layer gear 4 is equal to the rotation angular velocity of
the sun gear 10, thus realizing the function of increasing speed.
In this way, in the case of small torque and high rotating speed,
drilling can be conducted as long as a drill bit is installed at
the end of the mounting shaft 14.
[0048] The matching process of the steel balls 9c and the different
limiting holes 1d1 allows positioning workers to adjust to the
required positions, and can also avoid the out-of-gear event.
Embodiment 2
[0049] A transmission system, as shown in FIG. 11, is based on
embodiment 1, the side, facing the corresponding lifting pin 7b, of
each protrusion 9b is provided with a concave cambered surface 9b1,
and the end of each lifting pin 7b is a spherical surface 7b1.
Here, each concave cambered surface 9b1 is matched with the end of
the corresponding lifting pin 7b, so that when the protrusions 9b
push the lifting pins 7b, the concave cambered surfaces 9b1
restrain the lifting pins 7b, thus effectively ensuring the
restriction of the concave cambered surfaces 9b1 to the lifting
pins 7b and avoiding the out-of-gear event during high-speed output
of the transmission system.
Embodiment 3
[0050] A transmission system, as shown in FIG. 12, differs from
embodiment 2 only in that the side, facing the corresponding
lifting pin 7b, of each protrusion 9b is provided with a tapered
groove 9b2, and the end of each lifting pin 7b is tapered 7b2. In
this way, each tapered groove 9b2 can be matched with the end of
the corresponding lifting pin 7b, so that on the one hand, the
lifting pins 7b can smoothly slide into the tapered grooves 9b2,
and on the other hand, the tapered grooves 9b2 can limit the
lifting pins 7b, thus ensuring that the lifting pins 7b and the
protrusions 9b can remain stable during high-speed output of the
transmission system.
Embodiment 4
[0051] A transmission system, as shown in FIG. 13 and FIG. 14, is
based on embodiment 1, projection 12a are evenly distributed on the
side, facing the lifting rods 17b, of the third inner gear 12 along
the axial center of the third inner gear, the end of each lifting
rod 17b contacts with a ball 17c, and the balls 17c are limited in
the front housing body 1a. When the resistance on the mounting
shaft 14 is greater than the torque of the transmission system, the
transmission ring 13 will be locked, that is, it will not rotate on
its axis. However, the third planetary gear set 11 located on the
transmission ring 13 will still rotate on its axis under the action
of the second inner ring gear 10b of the sun gear 10 and drive the
third inner gear 12 sleeved outside to rotate. When the projection
12a pass through the balls 17c, the lifting rods 17b push up the
torque washer 17 so that the third inner gear 12 can rotate, thus
realizing the function of shaft disengagement.
[0052] In addition, here, the number of the limiting holes 1d1 of
the front cover 1d is twelve, the limiting holes are equally
divided into two groups, the two groups of limiting holes 1d1 are
symmetrical about the center of the front cover 1d, the number of
the steel balls 9c is two, and the steel balls are symmetrical
about the center of the torque cup 9. The two groups of limiting
holes 1d1 are equally divided into an equal number of low-speed
gears and an equal number of high-speed gears, and there are four
low-speed gears and two high-speed gears. Meanwhile, the limiting
holes 1d1 of the low-speed gears are located on the front cover 1d
corresponding to the middle position of two adjacent teeth 17a,
while the limiting holes 1d1 of the high-speed gears are not
located on the front cover 1d corresponding to the middle position
of two adjacent teeth 17a.
[0053] When the transmission system is in a low gear, that is, when
the steel balls 9c are engaged with the limiting holes 1d1 of the
low-speed gears, then the teeth 17a is corresponding to the gap
between the limiting blocks 1a2. If the mounting shaft 14 is locked
due to excessive resistance, the teeth 17a of the torque washer 17
can smoothly slide between two second limiting blocks 1a2 while the
projection 12a push up the lifting rods 17b, thus normally
realizing the process of shaft disengagement for avoiding danger.
When the transmission system is in a high gear, the teeth 17a are
blocked by the second limiting blocks 1a2, which prevents the
torque washer 17 from being pushed up by the projection 12a,
however, the resistance is not very large during this process, so
that shaft disengagement does not occur, and thus the drilling
process can proceed normally.
Embodiment 5
[0054] An electric tool is disclosed. A transmission system for the
electric tool is a transmission system recorded in any one of the
embodiments 1 to 4 of the invention.
[0055] The specific embodiments are only an explanation of the
invention, but not a limitation to the invention. After reading
this specification, a person skilled in the art can make
modifications to the embodiments without creative contribution as
needed, however, as long as they are within the scope of the claims
of the invention, they are protected by the patent law.
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