U.S. patent application number 12/847777 was filed with the patent office on 2011-05-19 for electric water pump.
This patent application is currently assigned to HYUNDAI MOTOR COMPANY. Invention is credited to Gyuhwan Kim, Kyung-Hwan Kim, Yun Seok Kim, Jong-Hoon Lee, Kwang-Ho Lee, Seung Yong Lee, Tae-Sung Oh, Yong Sun Park, Jeawoong Yi.
Application Number | 20110116953 12/847777 |
Document ID | / |
Family ID | 43902214 |
Filed Date | 2011-05-19 |
United States Patent
Application |
20110116953 |
Kind Code |
A1 |
Yi; Jeawoong ; et
al. |
May 19, 2011 |
Electric Water Pump
Abstract
An electric water pump may include a stator generating a
magnetic field, a rotor rotated by the magnetic field, a pump
cover, a body having a volute chamber with the pump chamber, a
stator chamber and a rotor chamber, the stator being mounted in the
stator chamber and the rotor being mounted in the rotor chamber, a
shaft fixed to the rotor, an impeller fixed to the shaft in the
volute chamber, a driver case mounted at a rear end of the body and
having a rear surface opened backward and formed of a driver
chamber therein, and a driver mounted in the driver chamber and
applying a control signal to the stator, wherein the case surface
is provided with an insert portion protruded forward from an
external circumference thereof and inserted in a rear end portion
of the body, and a fixing groove in which the insert portion is
inserted.
Inventors: |
Yi; Jeawoong; (Hwaseong-si,
KR) ; Lee; Seung Yong; (Yongin-si, KR) ; Kim;
Gyuhwan; (Suwon-si, KR) ; Kim; Yun Seok;
(Yongin-si, KR) ; Park; Yong Sun; (Yongin-si,
KR) ; Oh; Tae-Sung; (Ansan-si, KR) ; Kim;
Kyung-Hwan; (Incheon-si, KR) ; Lee; Jong-Hoon;
(Incheon-si, KR) ; Lee; Kwang-Ho; (Cheonan-si,
KR) |
Assignee: |
HYUNDAI MOTOR COMPANY
Seoul
KR
MYUNGHWA IND. CO., LTD.
Seoul
KR
AMOTECH CO., LTD.
Incheon-si
KR
KIA MOTORS CORPORATION
Seoul
KR
|
Family ID: |
43902214 |
Appl. No.: |
12/847777 |
Filed: |
July 30, 2010 |
Current U.S.
Class: |
417/423.7 ;
417/423.12 |
Current CPC
Class: |
F04D 29/628 20130101;
F04D 13/064 20130101; F04D 13/0633 20130101 |
Class at
Publication: |
417/423.7 ;
417/423.12 |
International
Class: |
F04B 17/03 20060101
F04B017/03 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 19, 2009 |
KR |
10-2009-0112234 |
Claims
1. An electric water pump apparatus including: a stator generating
a magnetic field according to a control signal; a rotor enclosed by
the stator and rotated by the magnetic field generated at the
stator; a pump cover having an inlet through which coolant flows in
and an outlet through which pressurized coolant flows out; a body
having: a front surface forming a volute chamber between the pump
cover and the front surface; a stator chamber formed at an outer
portion of the body in a radial direction, wherein the stator is
mounted in the stator chamber; and a rotor chamber formed at an
inner portion of the body in a radial direction, wherein the rotor
is mounted in the rotor chamber; a shaft having a central axis,
fixed to the rotor so as to rotate together with the rotor about
the central axis thereof, and mounted in the rotor chamber; and an
impeller fixed to a front portion of the shaft so as to rotate
together with the shaft, pressurizing the coolant having flowed in
through the inlet, and mounted in the volute chamber.
2. The electric water pump apparatus of claim 1, further including:
a driver case detachably mounted at a rear end of the body, formed
of a case surface at a front surface thereof, having a rear surface
opened backward, and including a driver chamber therein, and a
driver mounted in the driver chamber and applying the control
signal to the stator, wherein the case surface is provided with an
insert portion protruded forward from an external circumference
thereof and detachably inserted in a rear end portion of the body,
and a fixing groove in which the insert portion is inserted and
that prevents rotation of the stator is formed at an external
circumference of a rear end of the stator.
3. The electric water pump apparatus of claim 2, wherein a first
bearing is disposed between the shaft and the front surface of the
body in order to reduce rotational friction of the shaft.
4. The electric water pump apparatus of claim 3, wherein the rotor
is formed in an unsymmetrical shape so as to generate thrust toward
the front surface of the body.
5. The electric water pump apparatus of claim 4, wherein a cup is
mounted between the first bearing and the rotor on the shaft in
order to prevent interference and collision of the shaft and the
first bearing by the thrust, and a thrust ring is mounted between
the cup and the first bearing for smooth rotation of the shaft.
6. The electric water pump apparatus of claim 5, wherein the cup is
made of a rubber material and the thrust ring is made of a ceramic
material.
7. The electric water pump apparatus of claim 3, wherein a second
bearing is disposed between a rear end portion of the shaft and the
front surface of the driver case in order to reduce the rotational
friction of the shaft.
8. The electric water pump apparatus of claim 7, wherein the second
bearing is disposed between a step portion of the shaft at a rear
side thereof and the front surface of the driver case in order to
reduce the rotational friction of the shaft.
9. The electric water pump apparatus of claim 1, wherein the stator
includes: a stator core formed by stacking a plurality of pieces
made of a magnetic material, an insulator connecting pieces of the
stator core to each other, a coil coiling the stator core so as to
form a magnetic path, and a stator case wrapping and sealing the
stator core, the insulator, and the coil.
10. The electric water pump apparatus of claim 9, wherein a fixing
groove is formed at an external circumference of a rear end of the
stator case.
11. The electric water pump apparatus of claim 9, wherein an
interior circumference of the stator case forms a part of the rotor
chamber.
12. The electric water pump apparatus of claim 11, wherein the
rotor chamber is fluidly connected to the volute chamber, and the
stator chamber is fluidly closed and sealed to the rotor
chamber.
13. The electric water pump apparatus of claim 12, wherein a stator
groove is formed at an interior circumference of the stator case
along a length direction of the stator such that foreign substances
attached to the stator are removed along the stator groove by
coolant flow in the rotor chamber.
14. The electric water pump apparatus of claim 9, wherein a
plurality of damping holes for diminishing vibration and noise
according to rotation of the rotor are formed at the stator
case.
15. The electric water pump apparatus of claim 9, wherein the
stator case is made of a bulk mold compound including a potassium
family that has a low coefficient of contraction.
16. The electric water pump apparatus of claim 15, wherein the
stator further includes: a Hall sensor detecting a position of the
rotor, and a Hall sensor board controlling the control signal
supplied to the stator according to a position of the rotor
detected by the Hall sensor, wherein the Hall sensor and the Hall
sensor board are also wrapped and sealed by the stator case.
17. The electric water pump apparatus of claim 1, wherein the rotor
includes: a rotor core having a hollow cylindrical shape and made
of a magnetic material, a permanent magnet mounted at an exterior
circumference of the rotor core, a rotor cover mounted at both
distal ends of the rotor core and the permanent magnet so as to fix
the rotor core and the permanent magnet together, and a rotor case
wrapping an exterior circumference of the rotor core and the
permanent magnet together so as to fix the rotor core and the
permanent magnet in a state that the rotor core and the permanent
magnet are mounted at the rotor cover.
18. The electric water pump apparatus of claim 17, wherein the
rotor case is made of a bulk mold compound including a potassium
family that has a low coefficient of contraction.
19. The electric water pump apparatus of claim 17, wherein a first
bearing is disposed between the shaft and the front surface of the
body in order to reduce rotational friction of the shaft and
wherein a cup is mounted between the first bearing and the rotor on
the shaft in order to prevent interference and collision of the
shaft and the first bearing by a thrust, and a thrust ring is
mounted between the cup and the first bearing for smooth rotation
of the shaft.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims priority to Korean Patent
Application No. 10-2009-0112234 filed on Nov. 19, 2009, the entire
contents of which is incorporated herein for all purposes by this
reference.
BACKGROUND OF THE PRESENT INVENTION
[0002] 1. Field of the Present Invention
[0003] The present invention relates to an electric water pump.
More particularly, the present invention relates to an electric
water pump having improved performance and durability.
[0004] 2. Description of Related Art
[0005] Generally, a water pump circulates coolant to an engine and
a heater in order to cool the engine and heat a cabin. The coolant
flowing out from the water pump circulates through and exchanges
heat with the engine, the heater, or the radiator, and flows back
in the water pump. Such a water pump is largely divided into a
mechanical water pump and an electric water pump.
[0006] The mechanical water pump is connected to a pulley fixed to
a crankshaft of the engine and is driven according to rotation of
the crankshaft (i.e., rotation of the engine). Therefore, the
coolant amount flowing out from the mechanical water pump is
determined according to rotation speed of the engine. However, the
coolant amount required in the heater and the radiator is a
specific value regardless of the rotation speed of the engine.
Therefore, the heater and the radiator do not operate normally in a
region where the engine speed is slow, and in order to operate the
heater and the radiator normally, the engine speed must be
increased. However, if the engine speed is increased, fuel
consumption of a vehicle also increases.
[0007] On the contrary, the electric water pump is driven by a
motor controlled by a control apparatus. Therefore, the electric
water pump can determines the coolant amount regardless of the
rotation speed of the engine. Since components used in the electric
water pump, however, are electrically operated, it is important for
electrically operated components to have sufficient waterproof
performance. If the components have sufficient waterproof
performance, performance and durability of the electric water pump
may also improve.
[0008] Currently, the number of vehicles having an electric water
pump is tending to increase. Accordingly, various technologies for
improving performance and durability of the electric water pump are
being developed.
[0009] The information disclosed in this Background of the present
invention section is only for enhancement of understanding of the
general background of the present invention and should not be taken
as an acknowledgement or any form of suggestion that this
information forms the prior art already known to a person skilled
in the art.
BRIEF SUMMARY OF THE PRESENT INVENTION
[0010] Various aspects of the present invention are directed to
provide an electric water pump having advantages of improved
performance and durability.
[0011] In an aspect of the present invention, the electric water
pump apparatus may include a stator generating a magnetic field
according to a control signal, a rotor enclosed by the stator and
rotated by the magnetic field generated at the stator, a pump cover
having an inlet through which coolant flows in and an outlet
through which pressurized coolant flows out, a body having: a front
surface forming a volute chamber between the pump cover and the
front surface, a stator chamber formed at an outer portion of the
body in a radial direction, wherein the stator is mounted in the
stator chamber, and a rotor chamber formed at an inner portion of
the body in a radial direction, wherein the rotor is mounted in the
rotor chamber, a shaft having a central axis, fixed to the rotor so
as to rotate together with the rotor about the central axis
thereof, and mounted in the rotor chamber, and an impeller fixed to
a front portion of the shaft so as to rotate together with the
shaft, pressurizing the coolant having flowed in through the inlet,
and mounted in the volute chamber.
[0012] The electric water pump apparatus may further include a
driver case detachably mounted at a rear end of the body, formed of
a case surface at a front surface thereof, having a rear surface
opened backward, and including a driver chamber therein, and a
driver mounted in the driver chamber and applying the control
signal to the stator, wherein the case surface is provided with an
insert portion protruded forward from an external circumference
thereof and detachably inserted in a rear end portion of the body,
and a fixing groove in which the insert portion is inserted and
that prevents rotation of the stator is formed at an external
circumference of a rear end of the stator.
[0013] A first bearing may be disposed between the shaft and the
front surface of the body in order to reduce rotational friction of
the shaft, wherein the rotor is formed in an unsymmetrical shape so
as to generate thrust toward the front surface of the body.
[0014] A cup may be mounted between the first bearing and the rotor
on the shaft in order to prevent interference and collision of the
shaft and the first bearing by the thrust, and a thrust ring is
mounted between the cup and the first bearing for smooth rotation
of the shaft, wherein the cup is made of a rubber material and the
thrust ring is made of a ceramic material.
[0015] A second bearing may be disposed between a rear end portion
of the shaft and the front surface of the driver case in order to
reduce the rotational friction of the shaft, wherein the second
bearing is disposed between a step portion of the shaft at a rear
side thereof and the front surface of the driver case in order to
reduce the rotational friction of the shaft.
[0016] The stator may include a stator core formed by stacking a
plurality of pieces made of a magnetic material, an insulator
connecting pieces of the stator core to each other, a coil coiling
the stator core so as to form a magnetic path, and a stator case
wrapping and sealing the stator core, the insulator, and the coil,
wherein a fixing groove is formed at an external circumference of a
rear end of the stator case, wherein an interior circumference of
the stator case forms a part of the rotor chamber.
[0017] The rotor chamber may be fluidly connected to the volute
chamber, and the stator chamber is fluidly closed and sealed to the
rotor chamber, wherein a stator groove is formed at an interior
circumference of the stator case along a length direction of the
stator such that foreign substances attached to the stator are
removed along the stator groove by coolant flow in the rotor
chamber.
[0018] A plurality of damping holes for diminishing vibration and
noise according to rotation of the rotor may be formed at the
stator case.
[0019] The stator case may be made of a bulk mold compound
including a potassium family that has a low coefficient of
contraction, wherein the stator further includes, a Hall sensor
detecting a position of the rotor, and a Hall sensor board
controlling the control signal supplied to the stator according to
a position of the rotor detected by the Hall sensor, wherein the
Hall sensor and the Hall sensor board are also wrapped and sealed
by the stator case.
[0020] The rotor may include a rotor core having a hollow
cylindrical shape and made of a magnetic material, a permanent
magnet mounted at an exterior circumference of the rotor core, a
rotor cover mounted at both distal ends of the rotor core and the
permanent magnet so as to fix the rotor core and the permanent
magnet together, and a rotor case wrapping an exterior
circumference of the rotor core and the permanent magnet together
so as to fix the rotor core and the permanent magnet in a state
that the rotor core and the permanent magnet are mounted at the
rotor cover.
[0021] The rotor case may be made of a bulk mold compound including
a potassium family that has a low coefficient of contraction,
wherein a first bearing is disposed between the shaft and the front
surface of the body in order to reduce rotational friction of the
shaft and wherein a cup is mounted between the first bearing and
the rotor on the shaft in order to prevent interference and
collision of the shaft and the first bearing by a thrust, and a
thrust ring is mounted between the cup and the first bearing for
smooth rotation of the shaft.
[0022] The methods and apparatuses of the present invention have
other features and advantages which will be apparent from or are
set forth in more detail in the accompanying drawings, which are
incorporated herein, and the following Detailed Description of the
present invention, which together serve to explain certain
principles of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a perspective view of an exemplary electric water
pump according to the present invention.
[0024] FIG. 2 is a cross-sectional view taken along the line A-A in
FIG. 1.
[0025] FIG. 3 is a perspective view showing a stator of an
exemplary electric water pump according to the present
invention.
[0026] It should be understood that the appended drawings are not
necessarily to scale, presenting a somewhat simplified
representation of various features illustrative of the basic
principles of the present invention. The specific design features
of the present invention as disclosed herein, including, for
example, specific dimensions, orientations, locations, and shapes
will be determined in part by the particular intended application
and use environment.
[0027] In the figures, reference numbers refer to the same or
equivalent parts of the present invention throughout the several
figures of the drawing.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
[0028] Reference will now be made in detail to various embodiments
of the present invention(s), examples of which are illustrated in
the accompanying drawings and described below. While the present
invention(s) will be described in conjunction with exemplary
embodiments, it will be understood that present description is not
intended to limit the present invention(s) to those exemplary
embodiments. On the contrary, the present invention(s) is/are
intended to cover not only the exemplary embodiments, but also
various alternatives, modifications, equivalents and other
embodiments, which may be included within the spirit and scope of
the present invention as defined by the appended claims.
[0029] An exemplary embodiment of the present invention will
hereinafter be described in detail with reference to the
accompanying drawings.
[0030] FIG. 1 is a perspective view of an electric water pump
according to an exemplary embodiment of the present invention, and
FIG. 2 is a cross-sectional view taken along the line A-A in FIG.
1.
[0031] As shown in FIG. 1 and FIG. 2, an electric water pump 1
according to an exemplary embodiment of the present invention
includes a pump cover 10, a body 30, a driver case 50, and a driver
cover 70. The body 30 is engaged to a rear end of the pump cover 10
so as to form a volute chamber 16, the driver case 50 is engaged to
a rear end of the body 30 so as to form a rotor chamber 38 and a
stator chamber 42, and the driver cover 70 is engaged to a rear end
of the driver case 50 so as to form a driver chamber 64.
[0032] In addition, an impeller 22 is mounted in the volute chamber
16, a rotor (84, 86, 88, and 90) fixed to a shaft 82 is mounted in
the rotor chamber 38, a stator 101 is mounted in the stator chamber
42, and a driver 80 is mounted in the driver chamber 64. The shaft
82 has a central axis x, and the rotor (84, 86 88, and 90) as well
as the shaft 82 rotate about the central axis x. The stator 101 is
disposed coaxially with the central axis x of the shaft 82.
[0033] The pump cover 10 is provided with an inlet 12 at a front
end portion thereof and an outlet 14 at a side portion thereof.
Therefore, the coolant flows in the electric water pump 1 through
the inlet 12, and the pressurized coolant in the electric water
pump 1 flows out through the outlet 14. A slanted surface 18 is
formed at a rear end portion of the inlet 12 of the pump cover 10,
and a rear end portion 20 of the pump cover 10 is extended rearward
from the slanted surface 18. The rear end portion 20 of the pump
cover 10 is engaged to a cover mounting portion 44 of the body 30
by fixing means such as a bolt B. The slanted surface 18 is slanted
with reference to the central axis x of the shaft 82, and an
intersecting point P of lines extended from the slanted surface 18
is located on the central axis x of the shaft 82.
[0034] The volute chamber 16 for pressurizing the coolant is formed
in the pump cover 10, and the impeller 22 for pressurizing and
discharging the coolant through the outlet 14 is mounted in the
volute chamber 16. The impeller 22 is fixed to a front end portion
of the shaft 82 and rotates together with the shaft 82. For this
purpose, a bolt hole 29 is formed at a middle portion of the
impeller 22 and a thread is formed at an interior circumference of
the bolt hole 29. Therefore, an impeller bolt 28 inserted in the
bolt hole 29 is threaded to the front end portion of the shaft 82
such that the impeller 22 is fixed to the shaft 82. A washer w may
be interposed between the impeller 22 and the impeller bolt 28.
[0035] The impeller 22 is provided with a confronting surface 26
corresponding to the slanted surface 18 at the front end portion
thereof. Therefore, an intersecting point of lines extended from
the confronting surface 26 is also positioned on the central axis x
of the shaft 82. The coolant having flowed into the water pump 1
may be smoothly guided and performance of the water pump 1 may be
improved as a consequence of disposing centers of the impeller 22
and the rotor (84, 86, 88, and 90) that are rotating elements of
the water pump 1 and a center of the stator 101 that is a fixed
element of the water pump 1 on the central axis x.
[0036] In addition, the impeller 22 is divided into a plurality of
regions by a plurality of blades 24. The coolant having flowed into
the plurality of regions is pressurized by rotation of the impeller
22.
[0037] The body 30 has a hollow cylindrical shape that is opened
rearward, and is engaged to the rear end of the pump cover 10. The
body 30 includes a front surface 32 forming the volute chamber 16
with the pump cover 10, the stator chamber 42 that is formed at an
external circumferential portion of the body 30 and in which the
stator 101 is mounted, and the rotor chamber 38 that is formed at
an interior circumferential portion of the stator chamber 42 and in
which the rotor (84, 86, 88, and 90) is mounted.
[0038] The front surface 32 of the body 30 is provided with the
cover mounting portion 44, a first stator mounting surface 40, a
first bearing mounting surface 48, and a penetration hole 34 formed
sequentially from an exterior circumference to a center
thereof.
[0039] The cover mounting portion 44 is engaged to the rear end
portion 20 of the pump cover 10. Sealing means such as an O-ring O
may be interposed between the cover mounting portion 44 and the
rear end portion 20 in order to prevent leakage of the coolant from
the volute chamber 16.
[0040] The first stator mounting surface 40 is protruded rearward
from the front surface 32, and defines a boundary between the
stator chamber 42 and the rotor chamber 38. In a state that the
sealing means such as an O-ring O is mounted at the first stator
mounting surface 40, the front end of the stator 101 is mounted at
the first stator mounting surface 40.
[0041] The first bearing mounting surface 48 is protruded rearward
from the front surface 32. A first bearing 94 is interposed between
the first bearing mounting surface 48 and the front end portion of
the shaft 82 in order to make the shaft 82 smoothly rotate and to
prevent the shaft 82 from being inclined.
[0042] The penetration hole 34 is formed at a middle portion of the
front surface 32 such that the front end portion of the shaft 82 is
protruded to the volute chamber 16 through the penetration hole 34.
The impeller 22 is fixed to the shaft 82 in the volute chamber 16.
It is exemplarily described in this specification that the impeller
22 is fixed to the shaft 82 by the impeller bolt 28. However, the
impeller 22 may be press-fitted to an exterior circumference of the
shaft 82.
[0043] Meanwhile, a connecting hole 36 is formed at the front
surface 32 between the first stator mounting surface 40 and the
first bearing mounting surface 48. Therefore, the rotor chamber 38
is fluidly connected to the volute chamber 16. Heat generated at
the shaft 82, the rotor (84, 86, 88, and 90), and the stator 101 by
operation of the water pump 1 is cooled by the coolant flowing in
and out through the connecting hole 36. Therefore, durability of
the water pump 1 may improve. In addition, floating materials in
the coolant are prevented from being accumulated in the rotor
chamber 38.
[0044] The rotor chamber 38 is formed at a middle portion in the
body 30. The shaft 82 and the rotor (84, 86, 88, and 90) is mounted
in the rotor chamber 38.
[0045] A stepped portion 83, the diameter of which is larger than
that of the other part, is formed at a middle portion of the shaft
82. According to an exemplary embodiment of the present invention,
a hollow shaft 82 may be used.
[0046] The rotor (84, 86, 88, and 90) is fixed on the stepped
portion 83 of the shaft 82, and is formed in an unsymmetrical
shape. Thrust is exerted on the shaft 82 toward the front surface
32 by the unsymmetrical shape of the rotor (84, 86, 88, and 90) and
a pressure difference between the volute chamber 16 and the rotor
chamber 38. The thrust generated at the shaft 82 pushes the shaft
82 toward the front surface 32. Thereby, the stepped portion 83 of
the shaft 82 may be interfere and collide with the first bearing 94
and the first bearing 94 may be damaged, accordingly. In order to
prevent interference and collision of the stepped portion 83 of the
shaft 82 and the first bearing 94, a cup 100 is mounted between the
stepped portion 83 of the shaft 82 and the first bearing 94. Such a
cup 100 is made of an elastic rubber material, and relieves the
thrust of the shaft 82 exerted to the first bearing 94.
[0047] Meanwhile, in a case that the cup 100 directly contacts the
first bearing 94, the thrust of the shaft 82 exerted to the first
bearing 94 can be relieved. However, rotation friction may be
generated between the first bearing 94 and the cup 100 of a rubber
material, and thereby performance of the water pump 1 may be
deteriorated. Therefore, a thrust ring 98 is mounted between the
cup 100 and the first bearing 94 in order to reduce the rotation
friction between the first bearing 94 and the cup 100. That is, the
cup 100 reduces the thrust of the shaft 82 and the thrust ring 98
reduces the rotation friction of the shaft 82. It is exemplarily
described in this specification that a groove is formed at an
exterior circumference of the cup 100 and the thrust ring 98 is
mounted in the groove. However, a method for installing the thrust
ring 98 to the cup 100 is not limited to the exemplary embodiment
of the present invention. For example, a groove may be formed at a
middle portion of the cup 100 and the thrust ring 98 may be mounted
in this groove. Further, it is to be understood that any thrust
ring 98 interposed between the cup 100 and the first bearing 94 may
be included in the spirit of the present invention.
[0048] The rotor (84, 86, 88, and 90) includes a rotor core 86, a
permanent magnet 88, a rotor cover 84, and a rotor case 90.
[0049] The magnetic rotor core 86 has a cylindrical shape and is
fixed to the stepped portion 83 of the shaft 82 by press-fitting or
welding. The rotor core 86 is provided with a plurality of recesses
(not shown) formed along a length direction thereof at an exterior
circumference thereof, and the permanent magnet 88 is insertedly
mounted in each recesses.
[0050] The permanent magnet 88 is mounted at the exterior
circumference of the rotor core 86.
[0051] A pair of rotor covers 84 are mounted at both ends of the
rotor core 86 and the permanent magnet 88. The rotor cover 84
primarily fixes the rotor core 86 and the permanent magnet 88, and
is made of copper or stainless steel that has high specific
gravity.
[0052] In a state in which the rotor core 86 and the permanent
magnet 88 are mounted to the rotor cover 84, the rotor case 90
wraps exterior circumferences of the rotor core 86 and the
permanent magnet 88 so as to secondarily fix them. The rotor case
90 is made of a bulk mold compound (BMC) including a potassium
family that has a low coefficient of contraction. A method for
manufacturing the rotor case 90 will be briefly described.
[0053] The rotor core 86 and the permanent magnet 88 are mounted to
the rotor cover 84, and the rotor cover 84 to which the rotor core
86 and the permanent magnet 88 are mounted is inserted in a mold
(not shown). After that, the bulk mold compound including the
potassium family is melted and high temperature (e.g., 150.degree.
C.) and high pressure BMC is flowed into the mold. Then, the BMC is
cooled in the mold. As described above, if the rotor case 90 is
made of BMC having the low coefficient of contraction, the rotor
case 90 can be precisely manufactured. In general, the coefficient
of contraction of a resin is 4/1000-5/1000, but the coefficient of
contraction of the BMC is about 5/10,000. If the rotor case 90 is
manufactured by flowing the high temperature resin into the mold,
the rotor case 90 is contracted and does not have a target shape.
Therefore, if the rotor case 90 is manufactured by the BMC
including the potassium family that has the low coefficient of
contraction, contraction of the rotor case 90 by cooling may be
reduced and the rotor case 90 may be precisely manufactured. In
addition, since BMC including the potassium family has good
heat-radiating performance, the rotor can be cooled independently.
Therefore, the water pump may be prevented from being heat
damaged.
[0054] In addition, according to a conventional method for
manufacturing the rotor, the permanent magnet is fixed to the
exterior circumference of the rotor core with glue. However, as the
rotor rotates, high temperature and high pressure are generated
near the rotor. Thereby, the glue may be melted or the permanent
magnet may be disengaged from the rotor core. The permanent magnet
88 mounted to the rotor core 86, on the contrary, is fixed
primarily by the rotor cover 84 and secondarily by the rotor case
90 according to an exemplary embodiment of the present invention.
Thus, the permanent magnet 88 may not be disengaged from the rotor
core 86.
[0055] The stator chamber 42 is formed in the body 30 at a radially
outer portion of the rotor chamber 38. The stator 101 is mounted in
the stator chamber 42.
[0056] The stator 101 is fixed to the body 30 directly or
indirectly, and includes a stator core 102, an insulator 104, a
coil 108, and a stator case 109.
[0057] The stator core 102 is formed by stacking a plurality of
pieces made of a magnetic material. That is, the plurality of thin
pieces are stacked up such that the stator core 102 has a target
thickness.
[0058] The insulator 104 connects the pieces making up the stator
core 102 to each other, and is formed by molding a resin. That is,
the stator core 102 formed by stacking the plurality of pieces is
inserted in a mold (not shown), and then molten resin is injected
into the mold. Thereby, the stator core 102 at which the insulator
104 is mounted is manufactured. At this time, coil mounting
recesses 106 are formed at front and rear end portions of the
stator core 102 and the insulator 104.
[0059] The coil 108 is coiled at an exterior circumference of the
stator core 102 so as to form a magnetic path.
[0060] The stator case 109 wraps and seals the stator core 102, the
insulator 104, and the coil 108. The stator case 109, the same as
the rotor case 90, is manufactured by insert molding the BMC
including the potassium family.
[0061] In addition, when the stator case 109 is insert molded, a
Hall sensor 112 and a Hall sensor board 110 may also be insert
molded. That is, the stator 101, the Hall sensor 112, and the Hall
sensor board 110 may be integrally manufactured as one
component.
[0062] The Hall sensor 112 detects the position of the rotor (84,
86, 88, and 90). A mark (not shown) for representing the position
thereof is formed at the rotor (84, 86, 88, and 90), and the Hall
sensor 112 detects the mark in order to detect the position of the
rotor (84, 86, 88, and 90).
[0063] The Hall sensor board 110 controls a control signal
delivered to the stator 101 according to the position of the rotor
(84, 86, 88, and 90) detected by the Hall sensor. That is, the Hall
sensor board 110 makes a strong magnetic field be generated at one
part of the stator 101 and a weak magnetic field be generated at
the other part of the stator 101 according to the position of the
rotor (84, 86, 88, and 90). Thereby, initial mobility of the water
pump 1 may be improved.
[0064] A case mounting portion 46 is formed at an exterior surface
of the rear end of the body 30.
[0065] The driver case 50 is engaged to the rear end of the body
30, and is formed of a case surface 52 at a front end portion
thereof. The rotor chamber 38 and the stator chamber 42 are formed
in the body 30 by engaging the driver case 50 to the rear end
portion of the body 30. A body mounting portion 60 is formed at an
external circumference of the front end portion of the driver case
50 and is engaged to the case mounting portion 46 by fixing means
such as a bolt B.
[0066] The case surface 52 is provided with an insert portion 54, a
second stator mounting surface 56, and a second bearing mounting
surface 58 formed sequentially from an exterior circumference to a
center thereof.
[0067] The insert portion 54 is formed at an external
circumferential portion of the case surface 52 and is protruded
forward. The insert portion 54 is inserted in and closely contacted
to the rear end portion of the body 30. Sealing means such as an
O-ring O is interposed between the insert portion 54 and the rear
end portion of the body 30 so as to close and seal the stator
chamber 42.
[0068] The second stator mounting surface 56 is protruded forward
from the case surface 52 so as to define the boundary between the
stator chamber 42 and the rotor chamber 38. The rear end of the
stator 101 is mounted at the second stator mounting surface 56 with
a sealing means such as an O-ring O being interposed. The stator
chamber 42 is not fluidly connected to the rotor chamber 38 by the
O-ring O interposed between the first stator mounting surface 40
and the front end of the stator 101 and the O-ring O interposed
between the second stator mounting surface 56 and the rear end of
the stator 101. Therefore, the coolant having flowed in the rotor
chamber 38 does not flow to the stator chamber 42.
[0069] The second bearing mounting surface 58 is protruded
forwardly from the case surface 52. A second bearing 96 is
interposed between the second bearing mounting surface 58 and the
rear end portion of the shaft 82 so as to make the shaft 82
smoothly rotate and to prevent the shaft 82 from being
inclined.
[0070] The rear end of the driver case 50 is open. The driver
chamber 64 is formed between the driver case 50 and the driver
cover 70 by engaging the driver cover 70 of a disk shape to the
rear end of the driver 50 by fixing means such as a bolt B. For
this purpose, a protruding portion 72 is protruded forward from an
exterior circumference of the driver cover 70, and this protruding
portion 72 is inserted in and closely contacted to an exterior
circumference 62 of the rear end of the driver case 50. Sealing
means such as an O-ring O is interposed between the protruding
portion 72 and the exterior circumference 62 so as to prevent
foreign substances such as dust from entering the driver chamber
64.
[0071] The driver 80 controlling operation of the water pump 1 is
mounted in the driver chamber 64. The driver 80 includes
microprocessors and a printed circuit board (PCB). The driver 80 is
electrically connected to a controller (not shown) disposed at an
exterior of the electric water pump 1 through a connector 74 and
receives a control signal of the controller. In addition, the
driver 80 is electrically connected to the Hall sensor board 110 so
as to transmit the control signal received from the controller to
the Hall sensor board 110.
[0072] Meanwhile, the driver chamber 64 is isolated from the rotor
chamber 38 by the case surface 52. Therefore, the coolant in the
rotor chamber 38 does not flow into the driver chamber 64.
[0073] Hereinafter, the stator 101 of the electric water pump 1
according to an exemplary embodiment of the present invention will
be described in further detail with reference to FIG. 3.
[0074] FIG. 3 is a perspective view showing a stator of an electric
water pump according to an exemplary embodiment of the present
invention.
[0075] As shown in FIG. 3, a plurality of fixing grooves 105 are
formed at the external circumference of the rear end of the stator
case 109. The insert portion 54 is inserted in the fixing groove
105 so as to limit rotational and axial movements of the stator 101
according to the rotation of the rotor (84, 86, 88, and 90). Such a
fixing groove 105 can be formed together with the stator case 109
when the stator case 109 is insert molded, and an additional
process or an additional device is not required for forming the
fixing groove 105. Therefore, processes for manufacturing the
stator 101 do not increase. In addition, since the stator 101 is
fixed to the body 30 neither with glue nor by press-fitting, the
stator 101 can be easily disassembled from the body 30. Therefore,
if the stator 101 is out of order, the stator 101 can be easily
replaced.
[0076] In addition, as shown in FIG. 2, the interior circumference
of the stator case 109 forms a part of the rotor chamber 38. As
described above, the coolant flows into the rotor chamber 38 and
moves in the rotor chamber 38 by rotation of the shaft 82 and the
rotor (84, 86, 88, and 90). Since a stator groove 122 is formed at
the interior circumference of the stator case 109 along the length
direction thereof, the coolant in the rotor chamber 38 flows along
the stator groove 122 and removes floating materials attached to
the interior circumference of the stator case 109. The shape of the
stator groove 122 can be easily determined by a person of ordinary
skill in the art considering the flow of the coolant in the rotor
chamber 38.
[0077] Further, in order to reduce vibration and noise according to
the rotation of the rotor (84, 86, 88, and 90) and to reduce
vibration generated when a vehicle drives, a plurality of damping
holes 120 are formed at the stator case 109. Vibration and noise
according to the rotation of the rotor (84, 86, 88, and 90) and
vibration generated when the vehicle drives are absorbed by
movement of gas in the stator chamber 42 through the damping hole
120. The position and shape of the damping hole 120 can be easily
determined by a person of ordinary skill in the art according to
vibration frequency and pressure frequency of the stator 101. In
addition, a frothing resin or sound absorbing material may be
filled in the damping hole 120 so as to further reduce vibration
and noise.
[0078] Meanwhile, the stator groove 122 and the damping hole 120
may be formed at the rotor (84, 86, 88, and 90). That is, grooves
(not shown) may be formed at the exterior circumference of the
rotor case 90 such that the coolant in the rotor chamber 38 flows
along the grooves and removes the floating materials attached to
the exterior circumference of the rotor case 90. In addition,
vibration and noise according to the rotation of the rotor (84, 86,
88, and 90) and vibration when the vehicle drives may be absorbed
by forming holes (not shown) at the rotor case 90.
[0079] Since a stator and a rotor that are electrically operated
are wrapped by a resin case having waterproof performance according
to an exemplary embodiment of the present invention, performance
and durability of an electric water pump may improve.
[0080] In addition, since a Hall sensor and a Hall sensor board are
mounted in the stator and a control signal is changed according to
an initial position of the rotor, initial mobility of the electric
water pump may improve.
[0081] Further, since the coolant flows in a rotor chamber where
the rotor is mounted, the rotor may be cooled and foreign materials
in the rotor chamber may be removed.
[0082] Since materials attached to the stator are removed by flow
of the coolant in the rotor chamber, performance of the water pump
may further improve.
[0083] In addition, vibration and noise may be reduced by means of
damping holes formed at a stator case.
[0084] For convenience in explanation and accurate definition in
the appended claims, the terms "interior", "exterior", and "inner"
are used to describe features of the exemplary embodiments with
reference to the positions of such features as displayed in the
figures.
[0085] The foregoing descriptions of specific exemplary embodiments
of the present invention have been presented for purposes of
illustration and description. They are not intended to be
exhaustive or to limit the invention to the precise forms
disclosed, and obviously many modifications and variations are
possible in light of the above teachings. The exemplary embodiments
were chosen and described in order to explain certain principles of
the invention and their practical application, to thereby enable
others skilled in the art to make and utilize various exemplary
embodiments of the present invention, as well as various
alternatives and modifications thereof. It is intended that the
scope of the invention be defined by the Claims appended hereto and
their equivalents.
* * * * *