Pump
There is disclosed a pump comprising a pump housing, an impeller, and a motor. The pump housing comprises a pump chamber and at least one communication port opening into this pump chamber. The impeller comprises a plurality of vanes and is rotatably disposed in the pump chamber. The motor has a plurality of phases, and rotates the impeller. The number of communication ports, the number of vanes, and the number of phases of the motor are set in such a manner as to indicate prime numbers.
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This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2004-163407, filed Jun. 1, 2004, the entire contents of which are incorporated herein by reference.
BACKGROUND1. Field
The present invention relates to a pump for use in feeding out a fluid.
2. Description of the Related Art
A central processing unit (CPU) for use in an electronic apparatus has a tendency wherein a heating amount during operation increases with raised processing speed or increased functions. As a countermeasure against this heat, in recent years, an electronic apparatus has been put to practical use, comprising a so-called liquid cooling system cooling device which cools the CPU using a liquid refrigerant having a specific heat much higher than that of air.
As a cooling device, as described in Japanese Patent No. 3452059, a device having a heat exchange type pump has been proposed. A contact heat exchange type pump closely adheres to a heating electronic component such as a CPU, the heating electronic component exchanges heat with the liquid refrigerant to thereby cool the heating electronic component, and further the liquid refrigerant is circulated.
As the pump applied to the cooling device, sound produced at a driving time has been required to be excessively reduced.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
A first embodiment of the present invention will be described hereinafter with reference to FIGS. 1 to 8. In the present embodiment, a pump of the present invention will be described in accordance with one example applied to a cooling device disposed in a portable computer which is an electronic apparatus.
FIGS. 1 to 3 show a portable computer 1 which is the electronic apparatus. The portable computer 1 comprises a main unit 2 and a display unit 3. The main unit 2 comprises a first housing 10 having a flat box shape. The first housing 10 comprises a bottom wall 11a, an upper wall 11b, a front wall 11c, right and left side walls 11e, 11d, and a rear wall 11f. The upper wall 11b supports a keyboard 12.
As shown in
As shown in
The first and second leg portions 15a, 15b, 16a, 16b contact the upper surface of a top plate B. As a result, the first housing 10 tilts in a front downward posture, and a gap S is formed between the bottom of the protruding portion 13 and the upper surface of the top plate B.
As shown in
As shown in
The second housing 20 is supported on a rear end portion of the first housing 10 via a hinge (not shown). Therefore, the display unit 3 between a closed position in which the unit is laid on the main unit 2 in such a manner as to cover the keyboard 12 from above and an opened position in which the unit rises with respect to the main unit 2 in such a manner as to expose the keyboard 12 or the screen 21a.
As shown in
As shown in
As shown in FIGS. 4 to 8, the pump 41 forcibly circulates the liquid refrigerant in the circulation path 43, and comprises a pump housing 50 which also functions as the heat receiving portion, an impeller 70, a motor 80 (see
The pump housing 50 has a flat box shape which is one size larger than the CPU 31 and whose flat face is substantially square. As shown in
As shown in
The corner portion C3 positioned diagonally to the corner portion C1 is cut among four corner portions C1 to C4 of the housing main body 51. This corner portion C3 is provided with a discharge tube 61 as a first communication portion which connects the inside of the pump housing 50 to the outside of the pump housing 50, and a suction tube 62 as a second communication portion which connects the inside of the pump housing 50 to the outside of the pump housing 50. The discharge tube 61 and the suction tube 62 are disposed horizontally at an interval therebetween. An upstream end of the discharge tube 61 and a downstream end of the suction tube 62 protrude to the outside via the housing main body 51.
A first communication tube 63 is disposed between the upstream end of the discharge tube 61 and the first communication port 59 disposed in the partition wall 56. A second communication tube 64 is disposed between the downstream end of the suction tube 62 and the second communication port 60 disposed in the partition wall 56. The first communication tube 63 and the second communication tube 64 are formed into a unit to constitute a communication tube unit 65.
That is, the upstream end of the discharge tube 61 communicates with the pump chamber 57 via the first communication tube 63 and the first communication port 59. The downstream end of the suction tube 62 communicates with the pump chamber 57 via the second communication tube 64 and the second communication port 60. It is to be noted that a hole 66 for gas/liquid separation may be disposed in the first communication tube 63 or the second communication tube 64. In this case, even when orientation of the pump housing 50 is changed in any direction, the position of the hole 66 is preferably set in such a manner as to be constantly under a liquid surface of the liquid refrigerant stored in the reserve tank 58.
Moreover, the outer surface (upper surface of the pump housing 50) of the upper wall 51a of the housing main body 51 has a stator containing concave portion (see
The disc-shaped impeller 70 is contained in the pump chamber 57 of the pump housing 50. The impeller 70 stirs the liquid refrigerant in the pump chamber 57, and feeds out the liquid refrigerant to the outside (circulation path 43) of the pump housing 50 from the pump housing 50. The impeller 70 is formed, for example, of a resin, and has a disc-shaped main body portion 71, a rotation shaft 72 passing through the center of the main body portion 71, and a plurality of vanes 73 disposed on at least one end face among a pair of end faces of the main body portion 71, for example, the end face facing the heat receiving plate 53. The number of vanes 73 of the impeller 70 is set in such a manner as to be a prime number. This impeller 70 has, for example, seventeen vanes 73. As shown in
As shown in
As shown in
Power conduction to the stator 82 is performed simultaneously, for example, with turning-on of a power supply of the portable computer 1. By the power conduction, a rotary magnetic field is generated in a peripheral direction of the stator 82, and this magnetic field is magnetically bonded to the magnet of the rotor 81. As a result, a torque along the peripheral direction of the rotor 81 is generated between the stator 82 and the rotor magnet 81a of the rotor 81, and the impeller 70 rotates in a clockwise direction.
As described above, the lower surface of the heat receiving plate 53 has a flat heat receiving face 54. On the other hand, as shown in
An end face 91 of the convex portion 90 has: a part (circular arc) 92 of a circle concentric to a rotation center O (rotation center O of the impeller 70 is on a central axis line L (see
The convex portion 90 satisfactorily feeds the liquid refrigerant which is taken into the pump chamber 57 from the second communication port 60 and which is passed in a peripheral direction in the pump chamber 57 by the impeller 70 to the outside of the pump chamber 57 from the first communication port 59. That is, since the convex portion 90 is disposed, a part of the liquid refrigerant stirred in the pump chamber 57 abuts the side surface of the convex portion 90, rides on the convex portion 90, and changes its circulation direction toward the first communication port 59. Therefore, the liquid refrigerant stirred in the pump chamber 57 can be satisfactorily fed to the outside of the pump chamber 57 from the first communication port 59.
As shown in
Additionally, sound produced in driving the above-described pump 41 is divided into a periodic sound and an a periodic sound. For example, there are the following periodic sounds:
-
- (1) sound which is produced at a time when a pressure fluctuation is generated in the liquid refrigerant with the rotation of the impeller 70 and which is determined by the number of vanes 73 of the impeller 70 and a rotation number of the impeller 70;
- (2) sound produced by the pressure fluctuation generated in the liquid refrigerant, when the vanes 73 of the impeller 70 pass through the communication ports 59, 60 opened in the pump chamber 57;
- (3) sound produced by the number determined by a product of the phase number of the motor 80 and the rotation number of the impeller 70, where the number determined by the phase number of the motor 80 is a multiple number of a product of the phase number (the number of coils 83 in the motor 80) of the stator 82 and the phase number (pole number of the rotor magnet 81a in the motor 80) of the rotor 81; and
- (4) sound produced by the pressure fluctuation produced in the liquid refrigerant, when the vanes 73 of the impeller 70 pass through the convex portion 90.
As shown in
(the number of vanes 73 of the impeller 70×frequency of the rotation of the impeller 70)×n (n is a natural number) (5).
Therefore, the periodic sound produced by the pump 41 increases in a case where a value overlaps with a peak value of a sound pressure level developed in the above equation (5). For example, the followings are cases where the peak value of the sound pressure level produced by the above equation (5) overlaps with that of the sound pressure level of another periodic sound:
-
- (2′) the number of vanes 73 of the impeller 70 and communication ports 59, 60 opened in the pump chamber 57 have a common divisor;
- (3′) the number of vanes 73 of the impeller 70 and the phase number (number of coils 83 of the stator 82 in the motor 80) of the motor 80 have a common divisor; and
- (4′) θ2/θ1 is an integer, assuming that the angle formed by each pair of the adjacent vanes 73 is θ1, and the angle formed by a pair of edges of the end face 91 of the convex portion 90 is θ2.
Therefore, in the pump 41, the number of communication ports 59, 60, the number of vanes 73, and the number of coils 83 of the stator 82 which is the phase number of the motor 80 are all prime numbers. As shown in
It is to be noted that as a combination of the number of communication ports, the number of vanes, and the phase number of the motor, the number of communication ports is preferably set to two, the number of vanes is set to 23, and the motor is set to three poles.
In this case, the peak value of the sound pressure level of the sound produced by the pressure fluctuation of the liquid refrigerant when the impeller 70 rotates, the peak value of the sound pressure level of the sound produced by the pressure fluctuation in the liquid refrigerant when the vanes 73 of the impeller 70 pass through the communication ports 59, 60 opened in the pump chamber 57, and the peak value of the sound pressure level of the sound produced by the product of the number determined by the phase number of the motor 80 and the rotation number of the impeller 70 do not easily overlap. Therefore, the sound produced at a driving time of the pump 41 can be reduced.
Moreover, as shown in
Therefore, a timing at which the first communication port 59 and the vanes 73 of the impeller 70 pass each other, and a timing at which the second communication port 60 and the vanes 73 of the impeller 70 pass each other can be displaced. Therefore, the sound produced at the driving time of the pump 41 can be reduced.
In the pump 41 constituted in this manner, for example, the CPU 31 is laid on the printed circuit board 30 in such a manner as to cover the CPU 31 from above in a state in which the center of the pump housing 50 is matched with that (the same center as that of the IC chip 33) of the CPU 31. It is to be noted that the matching of the center of the pump housing 50 with that of the CPU 31 means that a perpendicular line passing through the center of the pump housing 50 passes through the center of the CPU 31.
As shown in
The boss portions 34 protrude upwards from the bottom wall 11a. The printed circuit board 30 is superimposed upon the tip surfaces of the boss portions 34.
In addition to the above-described attaching portions 68a, 68b, 68c, an attaching mechanism for attaching the pump 41 to the first housing 10 comprises three cylindrical inserts 100, three coil springs 101, three C-rings 102, three screws 103 and the like. Each insert 100 has a protruding portion 100a protruding to the outside in a horizontal direction along a peripheral direction in an upper end.
The pump 41 is fixed in a pressed state with respect to the CPU 31 as follows. It is to be noted that
First, the inserts 100 are passed through the coil springs 101. The insert 100 is inserted into the attaching portion 68a. The C-ring 102 for preventing falling is fitted in the insert 100. Accordingly, the insert 100 is in an urged state in a direction in which the protruding portion 100a is detached from the heat receiving plate 53 by the coil spring 101.
A thermally conductive grease (not shown) is applied to either the upper surface of the IC chip 33 or a region facing the IC chip 33 of the heat receiving face 54, and the heat receiving face 54 of the pump housing 50 is disposed facing the IC chip 33. The screws 103 are passed through the inserts 100, and screwed into the boss portions 34 on the printed circuit board 30. Accordingly, the inserts 100 are fixed to the boss portions 34, and the pump 41 is pressed onto the IC chip 33 by elastic properties of the coil springs 101. Consequently, the IC chip 33 is thermally connected to the heat receiving face 54 of the pump housing 50 via the conductive grease.
As shown in
The impeller 134 has a rotation center 134a, and a plurality of vanes 134b protruding radially from the rotation center. The impeller 134 is supported by the case 133 via a flat motor (not shown). In this motor, the impeller 134 is rotated in a counterclockwise direction as shown by arrows in
The heat emitting member 132 of the radiator 42 comprises a refrigerant passage 112 through which the liquid refrigerant flows and a plurality of heat emitting fins 113. The refrigerant passage 112 comprises, for example, a flat copper pipe, and has long and short axes. The refrigerant passage 112 has an annular shape which coaxially surrounds the impeller 134. This refrigerant passage 112 is superimposed upon the bottom of the protruding portion 13 in a posture of the short axis along the thickness direction of the first housing 10. Therefore, the refrigerant passage 112 is thermally connected to the first housing 10. The refrigerant passage 112 has an upstream end 114 and a downstream end 115. The upstream end 114 constitutes a refrigerant inlet 114a into which the liquid refrigerant flows, and the downstream end 115 constitutes a refrigerant outlet 115a from which the liquid refrigerant flows. The refrigerant passage 112, upstream end 114, and downstream end 115 form a part of the circulation path 43 (the circulation path 43 will be described later in detail).
Each heat emitting fin 113 is formed of a metal material superior in thermal conductivity, such as an aluminum alloy, and has a square plate shape. The heat emitting fins 113 are arranged at intervals in the peripheral direction of the impeller 134, and are radially arranged with respect to the impeller 134.
The heat emitting fins 113 rise along the thickness direction of the first housing 10. A lower end of the heat emitting fin 113 is fixed to the upper surface of the flat refrigerant passage 112 by means such as soldering. Accordingly, the arrangement intervals of the heat emitting fins 113 are determined, and the heat emitting fins 113 are thermally connected to the refrigerant passage 112. The upper ends of the heat emitting fins 113 abut the inner surface of the upper wall of the case 133, and are thermally connected to the case 133.
The circulation path 43 of the cooling device 40 has a first pipeline 121 and a second pipeline 122. The first pipeline 121 connects the discharge tube 61 of the pump housing 50 to the refrigerant inlet 114a of the refrigerant passage 112. The second pipeline 122 connects the suction tube 62 of the pump housing 50 to the refrigerant outlet 115a of the refrigerant passage 112.
In other words, the refrigerant passage 112 of the heat emitting member 132 functions as a third pipeline which connects the first pipeline 121 to the second pipeline 122. As a result, the liquid refrigerant circulates between a pump unit 25 and the radiator 42 through the first pipeline 121, the second pipeline 122, and the refrigerant passage 112.
Next, an operation of the cooling device 40 will be described.
The IC chip 33 of the CPU 31 generates heat during use of the portable computer 1. The heat emitted by the IC chip 33 is conducted to the pump housing 50 through the heat receiving face 54. Since the pump chamber 57 and the reserve tank 58 of the pump housing 50 are filled with the liquid refrigerant, the liquid refrigerant absorbs much of the heat conducted to the pump housing 50.
The power conduction to the stator 82 of the motor 80 is performed simultaneously with the turning-on of the power supply to the portable computer 1. Accordingly, a torque is generated between the stator 82 and the rotor magnet 81a of the rotor 81, and the rotor 81 rotates together with the impeller 70. When the impeller 70 rotates, the liquid refrigerant in the pump chamber 57 is pressurized and discharged from the discharge tube 61, and guided to the radiator 42 through the first pipeline 121.
In the pump 41, the number of communication ports 59, 60, the number of vanes 73, and the phase number (the number of coils 83 of the stator 82) of the motor 80 are set in such a manner as to be all prime numbers. Therefore, the peak value of the sound pressure level of the sound produced by the pressure fluctuation in the liquid refrigerant when the vanes 73 of the impeller 70 pass through the communication ports 59, 60 opened in the pump chamber 57, the peak value of the sound pressure level of the sound produced by the product of the number determined by the phase number of the motor 80 and the rotation number of the impeller 70, and the peak value of the sound pressure level produced by the pressure fluctuation in the liquid refrigerant when the impeller 70 rotates do not easily overlap. In the pump 41, assuming that the angle formed by each pair of adjacent vanes 73 is θ1, and the angle formed by one pair of the edges of the end face 91 of the convex portion 90 is θ2, these angles θ1 and θ2 are set in such a manner that θ2/θ1 is not an integer. Therefore, the timing at which the first communication port 59 and the vanes 73 of the impeller 70 pass each other, and the timing at which the second communication port 60 and the vanes 73 of the impeller 70 pass each other are displaced. Therefore, the sound produced at the driving time of the pump 41 is less than before.
The liquid refrigerant heated by heat exchange in the pump housing 50 is fed into the refrigerant passage 112 from the refrigerant inlet 114a. The liquid refrigerant flows toward the refrigerant outlet 115a in the refrigerant passage 112. In a flow process, the heat of the IC chip 33 absorbed by the liquid refrigerant is conducted to the refrigerant passage 112, and is further conducted to the heat emitting fins 113 from the refrigerant passage 112.
According to the present embodiment, since the refrigerant passage 112 is thermally connected to the protruding portion 13 of the first housing 10, the heat conducted to the refrigerant passage 112 from the liquid refrigerant can be diffused in the first housing 10. Moreover, since the heat emitting fins 113 are thermally connected to the upper wall of the case 133, the heat conducted to the heat emitting fins 113 from the liquid refrigerant can be released to the case 133.
When the impeller 134 of the radiator 42 rotates during the use of the portable computer 1, air is discharged radially from an outer peripheral portion of the impeller 134. The air passes through the adjacent heat emitting fins 113 as cooling air. Accordingly, the refrigerant passage 112 and the heat emitting fins 113 are cooled, and most of the heat conducted to both is taken away with the flow of cooling air. Moreover, this cooling air is discharged to the rear part of the first housing 10 via the first and second exhaust ports 17, 19 of the first housing 10 together with the heat. At this time, the second exhaust ports 19 are opened in the concave portion 14 of the bottom wall 11a. Moreover, when the portable computer 1 is laid on the top plate B of a desk, a gap S connected to the concave portion 14 is formed between the bottom wall 11a and the top plate B. Therefore, the cooling air discharged from the second exhaust ports 19 is discharged to the outside of the first housing 10 from the concave portion 14 via the gap S, and the flow of cooling air is not inhibited by the top plate B.
In contrast, the liquid refrigerant cooled by the heat exchange in the radiator 42 is guided into the suction tube 62 of the pump housing 50 from the refrigerant outlet 115a via the second pipeline 122. This liquid refrigerant is discharged to the inside of the pump housing 50 from the downstream end of the suction tube 62 through the second communication port 60.
The liquid refrigerant returned to the pump housing 50 is sucked into the pump chamber 57 from the communication port 60. The liquid refrigerant sucked into the pump chamber 57 is pressurized again and fed into the radiator 42 from the discharge tube 61.
When this cycle is repeated, the heat of the IC chip 33 is successively transferred to the heat emitting member 132 of the radiator 42, flows on the flow of cooling air passing among the heat emitting fins 113 of the heat emitting member 132, and is discharged to the outside of the portable computer 1.
As described above, according to the pump 41 of the present embodiment, the number of communication ports 59, 60, the number of vanes 73 of the impeller 70, and the phase number of the motor 80 are set in such a manner as to be all prime numbers. Therefore, the peak value of the sound pressure level of the sound produced by the pressure fluctuation in the liquid refrigerant when the vanes 73 of the impeller 70 pass through the communication ports 59, 60 opened in the pump chamber 57, the peak value of the sound pressure level of the sound produced by the product of the number determined by the phase number of the motor 80 and the rotation number of the impeller 70, and the peak value of the sound pressure level produced by the pressure fluctuation in the liquid refrigerant when the impeller 70 rotates do not easily overlap. Therefore, the sound produced at the driving time of the pump 41 can be reduced.
Moreover, according to the pump 41 of the present embodiment, assuming that the angle formed by the adjacent vanes 73 is θ1, and the angle formed by one pair of the edges 93a, 93b of the end face 91 of the convex portion 90 is θ2, these angles θ1 and θ2 are set in such a manner that θ2/θ1 is not an integer (the irrational number is achieved in the present embodiment). Therefore, the timing at which the first communication port 59 and the vanes 73 of the impeller 70 pass each other, and the timing at which the second communication port 60 and the vanes 73 of the impeller 70 pass each other are displaced. Therefore, the sound produced at the driving time of the pump 41 can be reduced.
Furthermore, in the pump 41 of the present embodiment, the pump housing 50 has the heat receiving face 54 thermally connected to the CPU 31 which is a heat emitting member. Therefore, this pump 41 functions not only as the heat exchanger which feeds out a fluid such as a liquid refrigerant but also as the heat receiving portion which receives the heat of a heating member such as a CPU 31. Additionally, the sound produced at the driving time of the pump 41 is small. Therefore, the pump can be preferably used in the liquid-cooling system cooling device 40 mounted on the electronic apparatus, for example, the portable computer 1.
A second embodiment of the present invention will be described with reference to
In a pump 41 of the present embodiment, the number of vanes 73 of an impeller 70 is set to a prime number, for example, 17. The vanes 73 are arranged in unequal intervals in such a manner that at least one of angles formed by each pair of adjacent vanes 73 has a different from the other said angles. The vanes 73 are arranged at unequal intervals in such a manner that the adjacent vanes 73 form different angles. At this time, preferably a value obtained by dividing an angle θ2 formed by a pair of edges 93a, 93b of an end face 91 of a convex portion 90 by an angle formed by the each pair of adjacent vanes 73 is not an integer.
It is to be noted that when the vanes 73 are arranged at unequal intervals (non-constant intervals), the number of vanes 73 does not necessarily have to be a prime number. Since another constitution is the same as that of the first embodiment including portions (not shown), the constitution is denoted with the same reference numerals, and redundant description is omitted.
According to the pump 41 of the present embodiment, the vanes 73 are arranged at unequal intervals (non-constant intervals) in such a manner that at least one of the angles formed by the each pair of adjacent vanes 73 is different from the other said angles. In this case, when the impeller 70 rotates, the timing at which the individual vanes 73 impart pressure changes to the liquid refrigerant can be displaced. The timing at which the first communication port 59 and the vanes 73 of the impeller 70 pass each other, and the timing at which the second communication port 60 and the vanes 73 of the impeller 70 pass each other can be displaced. Therefore, the sound produced at the driving time of the pump 41 can be reduced.
It is to be noted that the pump of the present invention can be used broadly not only in an electronic apparatus such as a portable computer but also in a cooling device mounted on the electronic apparatus, and another apparatus.
Claims
1. A pump comprising:
- a pump housing having a pump chamber and at least one communication port opening into this pump chamber;
- an impeller having a plurality of vanes and being rotatably disposed in the pump chamber; and
- a motor having a plurality of phases and rotating the impeller,
- wherein the number of communication ports, the number of vanes, and the number of phases of the motor are prime numbers.
2. The pump according to claim 1, wherein the plurality of vanes are arranged radially with respect to the center of rotation of the impeller, and
- the plurality of vanes are arranged at equal intervals in such a manner that the angle formed by each pair of adjacent vanes is constant.
3. The pump according to claim 2, wherein the pump housing has a pair of faces which define the pump chamber,
- a convex portion including an end face having a pair of edges extending radially from a position facing the center of rotation of the impeller is disposed on at least one face of the pair of faces, and,
- assuming that the angle formed by each pair of adjacent vanes is θ1, and the angle formed by the pair of edges of the end face of the convex portion is θ2, the angles θ1 and θ2 are set such that the value of θ2/θ1 is not an integer.
4. The pump according to claim 3, wherein, assuming that the angle formed by each pair of adjacent vanes is θ1, and the angle formed by the pair of edges of the end face of the convex portion is θ2, the angles θ1 and θ2 are set such that the value of θ2/θ1 is an irrational number.
5. The pump according to claim 1, wherein the plurality of vanes are arranged radially with respect to the center of rotation of the impeller, and
- the plurality of vanes are arranged at unequal intervals such that at least one of the angles formed by each pair of adjacent vanes is different from the other said angles.
6. The pump according to claim 1, wherein the pump housing has a heat receiving face thermally connected to a heat emitting member.
7. A pump comprising:
- a pump housing having a pump chamber and at least one communication port opening into this pump chamber;
- an impeller comprising a plurality of vanes and being rotatably disposed in the pump chamber;
- an annular rotor magnet disposed in the impeller; and
- a stator having a plurality of phases and being disposed inside the rotor magnet,
- wherein the number of communication ports, the number of vanes, and the number of phases of the stator are prime numbers.
8. The pump according to claim 7, wherein the plurality of vanes are arranged radially with respect to the center of rotation of the impeller, and
- the plurality of vanes are arranged at equal intervals in such a manner that the angle formed by each pair of adjacent vanes is constant.
9. The pump according to claim 8, wherein the pump housing has a pair of faces which define the pump chamber,
- a convex portion including an end face having a pair of edges extending radially from a position facing the center of rotation of the impeller is disposed on at least one face of the pair of faces, and,
- assuming that the angle formed by each pair of adjacent vanes is θ1, and the angle formed by the pair of edges of the end face of the convex portion is θ2, the angles θ1 and θ2 are set such that the value of θ2/θ1 is not an integer.
10. The pump according to claim 9, wherein, assuming that the angle formed by each pair of adjacent vanes is θ1, and the angle formed by the pair of edges of the end face of the convex portion is θ2, the angles θ1 and θ2 are set such that the value of θ2/θ1 is an irrational number.
11. The pump according to claim 7, wherein the plurality of vanes are arranged radially with respect to the center of rotation of the impeller, and
- the plurality of vanes are arranged at unequal intervals such that at least one of the angles formed by each pair of adjacent vanes is different from the other said angles.
12. The pump according to claim 7,wherein the pump housing has a heat receiving face thermally connected to a heat emitting member.
13. A pump comprising:
- a pump housing comprising a pump chamber;
- an impeller comprising a plurality of vanes and being rotatably disposed in the pump chamber; and
- a motor which rotates the impeller,
- wherein the plurality of vanes are arranged radially with respect to the center of rotation of the impeller, and in such a manner that the angles formed by each pair of adjacent vanes represent non-constant interval.
14. The pump according to claim 13,wherein the pump housing has a heat receiving face thermally connected to a heat emitting member.
Type: Application
Filed: Mar 17, 2005
Publication Date: Dec 1, 2005
Applicant: KABUSHIKI KAISHA TOSHIBA (Tokyo)
Inventors: Kentaro Tomioka (Sayama-shi), Katsumi Hisano (Matsudo-shi), Tomonao Takamatsu (Tokyo)
Application Number: 11/082,206