U.S. patent application number 11/308425 was filed with the patent office on 2007-09-27 for miniature pump for liquid cooling system.
Invention is credited to Qiao-Li Ding, Cheng-Tien Lai, Zhi-Yong Zhou.
Application Number | 20070224059 11/308425 |
Document ID | / |
Family ID | 38533639 |
Filed Date | 2007-09-27 |
United States Patent
Application |
20070224059 |
Kind Code |
A1 |
Lai; Cheng-Tien ; et
al. |
September 27, 2007 |
MINIATURE PUMP FOR LIQUID COOLING SYSTEM
Abstract
A miniature pump in accordance with the present invention
comprises a pump casing (10) and a liquid circulating unit (20)
received in the pump casing. The pump casing comprises a hollow
main body (14) transversely forming a spacing plate (126) and a
partition wall (144) spaced from the spacing plate. The liquid
circulating unit comprises a shaft (25) mounted between the
partition wall and the spacing plate, a bearing (27) rotatably
mounted the shaft, an impeller (26) attached to the bearing, a
first pair of spaced magnetic spacers (21,22) surrounding an upper
portion of the shaft and positioned above the bearing, and a second
pair of spaced magnetic spacers (23, 24) surrounding a lower
portion of the shaft and positioned below the bearing. The two
pairs of magnetic spacers properly suspend the impeller in a stable
position in an axial direction of the pump when the impeller
rotates.
Inventors: |
Lai; Cheng-Tien; (Shenzhen,
CN) ; Zhou; Zhi-Yong; (Shenzhen, CN) ; Ding;
Qiao-Li; (Shenzhen, CN) |
Correspondence
Address: |
NORTH AMERICA INTELLECTUAL PROPERTY CORPORATION
P.O. BOX 506
MERRIFIELD
VA
22116
US
|
Family ID: |
38533639 |
Appl. No.: |
11/308425 |
Filed: |
March 23, 2006 |
Current U.S.
Class: |
417/423.12 |
Current CPC
Class: |
F04D 29/048 20130101;
F04D 13/0666 20130101 |
Class at
Publication: |
417/423.12 |
International
Class: |
F04B 17/00 20060101
F04B017/00 |
Claims
1. A miniature pump for use with a liquid cooling system,
comprising: a pump casing comprising a hollow main body
transversely forming a spacing plate and a partition wall below and
spaced from the spacing plate; and a liquid circulating unit
received in a receiving space between the spacing plate and the
partition wall for circulating liquid in the liquid cooling system,
the liquid circulating unit comprising a shaft fixedly mounted
between the partition wall and the spacing plate, a bearing mounted
to the shaft and rotatable in respect thereto, an impeller attached
to the bearing to rotate therewith, a first pair of spaced magnetic
spacers surrounding an upper portion of the shaft and positioned
above the bearing, and a second pair of spaced magnetic spacers
surrounding a lower portion of the shaft and positioned below the
bearing; wherein the two pairs of magnetic spacers suspend the
impeller in a stable position in an axial direction of the shaft
when the impeller rotates so that the impeller is prevented from
rubbing against the partition wall when the impeller rotates.
2. The miniature pump as described in claim 1, wherein one of the
first pair of magnetic spacers is received in the impeller, and the
other one of the first pair of magnetic spacer is received in the
spacing plate.
3. The miniature pump as described in claim 1, wherein one of the
second pair of magnetic spacers is received in the impeller, and
the other one of the second pair of magnetic spacers is received in
the partition wall.
4. The miniature pump as described in claim 1, wherein each of the
magnetic spacers has a north pole and an opposite south pole, the
first pair of magnetic spacers have same poles at opposing surfaces
thereof so that a repulsive force exists between the first magnetic
spacers, and the second pair of magnets have same poles at opposing
surfaces thereof so that a repulsive force exists between the
second pair of magnetic spacers.
5. The miniature pump as described in claim 1, wherein the spacing
plate defines a through opening for allowing the liquid to enter
the receiving space.
6. The miniature pump as described in claim 1, wherein the
partition wall forms a shaft support defining a center blind hole
and a recess surrounding and communicating with the blind hole, an
end of the shaft is received in the blind hole, and one of the
second pair of magnetic spacers is received in the recess, and the
spacing plate forms a cap and a protrusion having an inner space
communicating with the cap, an opposite end the shaft is received
in the protrusion, and one of the first pair of magnetic spacers is
received in the cap.
7. The miniature pump as described in claim 6, wherein the impeller
comprises a center hollow post having a receiving room and a
plurality of blades, the other one of the first pair of magnetic
spacers is received in an upper portion of the receiving room, and
the other one of the second pair of magnetic spacers is received in
a lower portion of the receiving room.
8. The miniature pump as described in claim 7, wherein the blades
of the impeller comprises alternating first and second blades, the
first blades extend from the center post to an outer edge portion
of impeller and the second blades are formed at the outer edge
portion of the impeller.
9. The miniature pump as described in claim 1, further comprising a
motor driving unit received in the pump casing below the partition
wall for driving the impeller of the liquid circulating unit to
rotate.
10. The miniature pump as described in claim 9, wherein the
impeller carries a first permanent magnet, the motor driving unit
comprises a motor having a rotor, and a second permanent magnet is
attached to the rotor corresponding to the first permanent
magnet.
11. The miniature pump as described in claim 10, wherein the first
permanent magnet is embedded in the impeller.
12. The miniature pump as described in claim 10, wherein each of
the first and second permanent magnets comprises a ring-shaped flat
body, and an axial flux gap is created between the first and second
permanent magnets.
13. A liquid pump for use with a liquid cooling system, comprising:
a pump casing comprising a spacing plate having a first magnetic
spacer and a partition wall having a second magnetic spacer both
transversely formed therein to form an inner space between the
spacing plate and the partition wall for receiving a magnetically
levitated impeller therein, the impeller having a pair of third
magnetic spacers, one of the third magnetic spacers of the impeller
being received in an upper portion of the impeller and being
opposite to the first magnetic spacer of the spacing plate, and the
other one of the third magnetic spacers of the impeller being
received in a lower portion of the impeller and being opposite to
the second magnetic spacer of the partition wall; and a motor
driving unit positioned outside of the inner space to drive the
impeller to rotate; wherein when the impeller is rotated by the
motor, the impeller is suspended between the spacing plate and the
partition wall and total axial force to the impeller is
balanced.
14. The liquid pump as described in claim 13, wherein each of the
first, second and third magnetic spacers has a north pole and an
opposite south pole, the first magnetic spacer and the one of the
third magnetic spacers have same poles at opposing surfaces thereof
so that a repulsive force exists therebetween, the second magnetic
spacer and the other one of the third magnetic spacers have same
poles at opposing surfaces thereof so that a repulsive force exists
therebetween.
15. The liquid pump as described in claim 14, wherein the impeller
carries a first permanent magnet, the motor driving unit comprises
a rotor and a second permanent magnet attached to the rotor for
rotating therewith, and the second permanent magnet corresponds to
the first permanent magnet with a flux gap formed therebetween.
16. The liquid pump as described in claim 14, wherein the pump
casing comprises a hollow main body, a top cover hermetically
attached to a top end of the main body, and a bottom cover attached
to a bottom end of the main body to form a receiving space between
the partition wall and the bottom cover to receive the motor
driving unit therein.
17. A liquid pump, comprising: a pump casing comprising a liquid
inlet, a liquid outlet below the liquid inlet and a receiving space
therein; an impeller rotatably mounted in the receiving space,
wherein when the impeller rotates liquid is driven to flow into the
pump via the liquid inlet and out of the pump via the liquid
outlet, a magnet attached to the impeller; a first pair of magnetic
spacers mounted respectively on the impeller and the pump casing,
the first pair of magnets being so positioned that a repulsive
force exists therebetween, the repulsive force counteracting a
downward force acting on the impeller during rotation of the
impeller to drive the liquid to flow; and a motor driving unit
interacting with the magnet attached on the impeller to drive the
impeller to rotate.
18. The liquid pump as described in claim 17, further comprising a
second pair of magnetic spacers respectively mounted on the
impeller and the pump casing, the second pair of magnetic spacers
being so positioned that a repulsive force exists therebetween, the
second pair of magnetic spacers being located above the first pair
of magnetic spacers.
19. The liquid pump as described in claim 18, further comprising a
shaft, the impeller rotating around the shaft, the first pair of
magnetic spacers surrounding a lower portion of the shaft and
located below the impeller, and the second pair of magnetic spacers
surrounding an upper portion of the shaft and located above the
impeller.
20. The liquid pump as described in claim 19, wherein the motor
driving unit is located below the first pair of magnetic spacers.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to pumps, and more
particularly to a miniature pump having a magnetically levitated
impeller for a liquid cooling system for cooling an electronic
package.
DESCRIPTION OF RELATED ART
[0002] With the continued development of computer technology,
electronic packages such as the CPUs are generating more and more
heat that needs to be dissipated immediately to avoid damage to the
circuitry. Conventional heat dissipating devices such as heat
sink/fan combinations are not sufficiently effective at dissipating
heat to cope with modern circuitry. Liquid cooling systems have
thus been increasingly used in computer technology to cool these
electronic packages.
[0003] A typical liquid cooling system comprises a heat absorbing
unit for absorbing heat from a heat source, and a heat dissipating
unit which is filled with liquid. The liquid exchanges heat with
the heat absorbing unit, thereby taking away the heat of the heat
absorbing unit as the liquid is circulated. Typically, a pump is
used to circulate the liquid.
[0004] Generally, the pump comprises a housing having a bottom
plate, a shaft having a bearing pivotably attached thereto, an
impeller received in the housing and attached to the bearing, a
magnetic coupling structure, and a motor. The shaft passes through
the impeller and engages with the bottom plate of the housing. The
magnetic coupling structure comprises an inner magnet mounted on
the impeller and an outer magnet appropriately disposed on the
motor outside of the pump housing. In operation, the motor rotates
to drive the outer magnet to rotate therewith. The inner magnet
receives the attractive force of the outer magnet, so that the
inner magnet is caused to rotate at a high speed as a result of the
high-speed rotation of the outer magnet, thus causing the impeller
to rotate with high-speed. The impeller thus rotates with the inner
magnet to circulate the liquid in the liquid cooling system,
thereby taking away the heat. However, a problem existing in the
conventional pump is that during the high-speed rotation of the
pump there is friction between a bottom of the bearing and the
bottom plate of the housing of the pump because the axial attract
force of the outer magnet is applied on the impeller having the
inner magnet, which causes damage to the pump housing. A way of
reducing the friction between the bearing and the pump housing is
that a wearable washer is mounted between the bearing and the
bottom plate of the pump housing, however this can result in high
levels of unwanted noise pollution.
[0005] Therefore, there is a need for a pump with a low-friction
bearing
SUMMARY OF INVENTION
[0006] According to a preferred embodiment of the present
invention, a miniature pump comprises a pump casing and a liquid
circulating unit received in the pump casing. The pump casing
comprises a hollow main body transversely forming a spacing plate
and a partition wall separated from the spacing plate. The liquid
circulating unit comprises a shaft mounted between the partition
wall and the spacing plate, a bearing rotatably mounted mounted to
the shaft, an impeller attached to the bearing to rotate therewith,
a first pair of spaced magnetic spacers surrounding an upper
portion of the shaft and positioned above the bearing, and a second
pair of spaced magnetic spacers surrounding a lower portion of the
shaft and positioned below the bearing. The two pairs of magnetic
spacers suspend the impeller in a stable position in an axial
direction of the pump when the impeller rotates so that the
impeller is prevented from rubbing against the partition wall when
the impeller rotates.
[0007] Other advantages and novel features of the present invention
will become more apparent from the following detailed description
of preferred embodiment when taken in conjunction with the
accompanying drawings, in which:
BRIEF DESCRIPTION OF DRAWINGS
[0008] FIG. 1 is an exploded, isometric view of a miniature pump
according to a preferred embodiment of the present invention;
[0009] FIG. 2 is an assembled view of the miniature pump of FIG. 1;
and
[0010] FIG. 3 is a cross sectional view taken along line III-III of
FIG. 2.
DETAILED DESCRIPTION
[0011] Referring to FIGS. 1 and 2, a miniature pump in accordance
with a preferred embodiment of the present invention comprises a
pump casing 10 having an inner space, and a liquid circulating unit
20 and a motor driving unit 30 received in the inner space of the
pump casing 10.
[0012] The pump casing 10 comprises a hollow main body 14, a top
cover 12 hermetically attached to a top end 140 of the main body
14, and a bottom cover 16 attached to a bottom end 143 of the main
body 14. A sealing ring 141 is disposed between the main body 14
and the top cover 12 to prevent liquid leakage. The top cover 12
forms an annular groove 120 at a bottom edge thereof for receiving
the sealing ring 141 therein. An inlet 122 is formed on the top
cover 12 for allowing liquid to enter the pump casing 10. An outlet
142 is formed on the main body 14 for allowing the liquid to exit
the pump casing 10.
[0013] The main body 14 transversely forms an inner partition wall
144. This partition wall 144 effectively divides the inner space of
the main body 144 into a top space 146 and a bottom space 148.
[0014] Referring also to FIG. 3, a spacing plate 126 is
transversely arranged in the main body 14 as a guide means. The
spacing plate 126 further divides the top space 146 of the main
body 14 into a first chamber 145 between the spacing plate 126 and
the top cover 12, and a second chamber 147 between the partition
wall 144 and the spacing plate 126. A round cap 1260 protrudes
upwardly from a center of the spacing plate 126. A protrusion 1262
having an inner space communicating with the cap 1260 protrudes
from a top of the cap 1260. A plurality of through openings 1264 is
defined in the spacing plate 126 adjacent to the cap 1260 to
intercommunicate the first and second chambers 145, 147.
[0015] Referring to FIGS. 1 and 3, the liquid circulating unit 20
is mounted in the second chamber 147 of the pump casing 10. The
liquid circulating unit 20 comprises a shaft 25 mounted between the
partition wall 144 and the spacing plate 126, a bearing 27
pivotably attached to the shaft 25 and a magnetically levitated
impeller 26 attached to the bearing 27. A first permanent magnet
261 is embedded in the impeller 26. The first permanent magnet 261
has a substantially ring-shaped flat body magnetized so as to have
a plurality of alternating N and S poles along the ring body. The
impeller 26 comprises a center hollow post 260 having a receiving
room and a plurality of alternating first and second blades 262,
263, wherein the first blades 262 extend from the center post 260
to an outer edge portion of the impeller 26, and the second blades
263 are formed at the outer edge portion of the impeller 26. For
positioning the shaft 25, the partition wall 144 forms a shaft
support 1440 having a center blind hole 1442 receiving a bottom end
of the shaft 25 therein, and a top end of the shaft 25 engages in
the inner space of the protrusion 1262 of the spacing plate 126. An
annular recess 1444 communicating with and surrounding the blind
hole 1442 is defined in the shaft support 1440.
[0016] The motor driving unit 30 is received in the bottom space
148 of the pump casing 10. The motor driving unit 30 is positioned
on the bottom cover 16 and comprises a motor having a rotor 32. A
second permanent magnet 320 is attached to the rotor 32 for
rotating therewith, in a position corresponding to that of the
first permanent magnet 261 with a flux gap formed therebetween.
Like the first permanent magnet 261, the second permanent magnet
320 also has a ring flat body magnetized so as to have a plurality
of alternating N and S poles along the ring body.
[0017] In operation, the rotor 32 of the motor driving unit 30
rotates so as to drive the second permanent magnet 320 to rotate
therewith. The first permanent magnet 261 is driven to rotate with
second permanent magnet 340 by the attractive magnetic force
therebetween. The impeller 26 thus rotates with the first permanent
magnet 261 to circulate the liquid in the liquid cooling system. In
the present invention, the impeller 26 uses four annular magnetic
spacers 21-24 to control its axial position, wherein the magnetic
spacers 22, 23 are received in two opposite ends of the impeller 26
and rotate with the impeller 26, the magnetic spacers 21, 24 are
respectively fixedly received in the spacing plate 126 and the
partition wall 144. The magnetic spacers 21, 22 surround an upper
portion of the shaft 25 without connection therewith and are
positioned above the bearing 27. The magnetic spacers 21, 22 are
spaced and opposite to each other, wherein the magnetic spacer 21
is received in the cap 1260 of the spacing plate 126 and the
magnetic spacer 22 is received in an upper portion of the receiving
room of the post 260. Each of the magnets 21, 22 has a north (N)
pole and an opposite south (S) pole. The magnetic spacers 21, 22
are arranged so that the S pole of the magnetic spacer 21 opposes
the S pole of the magnetic spacer 22. The like magnetic poles
oppose each other so that a repulsive force F1 exists between the
magnetic spacers 21, 22, which means the impeller 26 with the
magnetic spacer 22 is pushed downwards with force F1 by the
magnetic spacer 21. When the impeller 26 rotates, the impeller 26
acts on the liquid with centrifugal force. Simultaneously, the
liquid acts on the impeller 26 with a corresponding force F. The
force F has an upward component F4 where the liquid acts on the
impeller 26 in an axial direction. The magnetic spacers 21, 22 are
used to provide the downward force F1 to the impeller 26 to balance
the upward axial force F4. The magnetic spacers 23, 24 surround a
lower portion of the shaft 25 without connection therewith and are
positioned below the bearing 27. The magnetic spacers 23, 24 are
located so as to be separate and opposite to each other, the
magnetic spacer 23 is received in a lower portion of the receiving
room of the post 260 and the magnetic spacer 24 is received in the
recess 1444 of the shaft support 1440. Each of the magnetic spacers
23, 24 has an N pole and an opposite S pole. The magnetic spacers
23, 24 are arranged so that the S pole of the second magnetic
spacer 23 opposes the S pole of the magnetic spacer 24. Since like
magnetic poles oppose each other so that a repulsive force F2
exists between the second magnets 23, 24, and the impeller 26 has
an upward force F2 exerted on it by the magnetic spacer 21. When
the impeller 26 rotates, an axial component force F3 pushes
downward on the impeller 26 because of a magnetic interaction
between the first permanent magnet 261 and the second magnet 320 of
the motor driving unit 30. The magnetic spacers 23, 24 are used to
provide the upward force F2 to the impeller 26 to balance the
downward axial force F3 and the force G of gravity acting on the
impeller 26. When the impeller 26 operates, total axial force
acting on the impeller 26 is balanced, wherein the total axial
force is illustrated by following equation: F1+G+F3=F2+F4. The four
magnetic spacers 21-24 properly suspend the impeller 26 in a stable
position in the axial direction such that a bottom of the impeller
26 has no contact with the partition wall 144, whereby a friction
between the bottom of the impeller 26 and the partition wall 144 is
prevented and noise pollution is considerably reduced.
[0018] It is to be understood, however, that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the invention, the disclosure is
illustrative only, and changes may be made in detail, especially in
matters of shape, size, and arrangement of parts within the
principles of the invention to the full extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed.
* * * * *