JP2009002245A - Centrifugal pump and liquid feeding device provided with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To discharge the gas staying in a pump chamber without damaging a pressurizing mechanism by rotation of an impeller. <P>SOLUTION: This centrifugal pump pressurizes liquid sucked from a suction port 12 by centrifugal force of rotation of an impeller 14, and feed out the same from a delivery port 13. A space between an outer edge part of the impeller 14 and an outer wall of a pump chamber holding the impeller communicates to a space outside of the pump chamber with an air discharge port 23 formed on the outer wall. Since gas is discharged through the air discharge port even if the air exists in a space where pressurized liquid is to be positioned, liquid to be re-circulated can be surely secured when bubbles is crushed by re-circulating part of pressurized liquid. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a centrifugal pump that sucks and discharges liquid by rotation of an impeller, and more particularly to a centrifugal pump that can also discharge liquid mixed with gas and a liquid supply apparatus including the centrifugal pump.

  Centrifugal pumps rotate the impeller and increase the pressure of the liquid by centrifugal force to discharge. Therefore, when gas is mixed, the gas and liquid are separated by the action of centrifugal force and the specific gravity is lighter than that of the liquid. The gas stays in the center of the impeller, and the liquid discharge capability decreases.

  For this reason, in the case of discharging liquid mixed with gas, an annular passage that penetrates in the axial direction is provided near the center of the impeller so that the liquid whose pressure is increased by the rotation of the impeller The gas (bubbles) retained by this jetting is pulverized into microbubbles by going around the secondary flow path from the outer peripheral side to the back side and ejecting from the annular flow path to the space where the gas is retained. There is provided a gas in which the gas in this state is discharged together with the liquid by the rotation of the impeller.

  However, if the gas stays in the sub-flow channel before the pump is driven, the high-pressure liquid for crushing the bubbles through the ring flow channel cannot be supplied, resulting in an inoperable state.

An exhaust pipe that passes through the center of the drive mechanism for rotationally driving the impeller and is inserted to the position of the impeller along the rotational axis of the impeller is provided, and gas is discharged through the exhaust pipe In Patent Document 1, although there is no inoperable state due to gas retention in the sub-flow channel, negative pressure is generated by an exhaust pipe having one end located in the main flow channel from the liquid suction port to the discharge port. Therefore, it is difficult to obtain sufficient performance.
JP-A-4-41998

  The present invention has been invented in view of the above-described conventional problems, and uses a pump capable of discharging the gas retained in the pump chamber without losing the pressure increasing mechanism by rotating the impeller as much as possible. An object of the present invention is to provide a liquid supply apparatus.

  In order to solve the above-mentioned problems, the present invention provides an impeller comprising a impeller that is driven to rotate, pressurizing liquid sucked from a suction port by rotation of the impeller by centrifugal force, and feeding the liquid from the discharge port. The space between the outer edge of the pump chamber and the outer wall of the pump chamber accommodating the impeller is characterized in that it communicates with the space outside the pump chamber through an exhaust port formed in the outer wall. The space between the outer edge of the impeller and the outer wall of the pump chamber is communicated with the space outside the pump chamber through the exhaust port, and even if there is gas in the space where the pressurized liquid is located, this is done through the exhaust port. It is designed to be discharged. When a part of the pressurized liquid is circulated to crush the bubbles, the liquid to be circulated can be ensured.

  The exhaust ports are preferably open at one end near the bottom surface of the impeller and provided at a plurality of locations in the circumferential direction of the impeller.

  The liquid supply apparatus according to the present invention is characterized in that the above centrifugal pump is disposed in a tank that stores liquid to be sent out by the centrifugal pump. This does not cause a problem if liquid leaks through the exhaust port.

  In the present invention, an exhaust port that communicates the space between the outer edge of the impeller and the outer wall of the pump chamber to the space outside the pump chamber prevents gas from staying in the space where the pressurized liquid is located. For this reason, a part of the pressurized liquid is circulated to crush the bubbles, so that the liquid to be circulated can be reliably ensured even when the liquid mixed with gas is discharged. In addition, the pump performance does not become inoperable, and the deterioration of the pump performance due to the provision of the exhaust port is small because a large cross-sectional area is not required as the exhaust port.

  The exhaust port has one end opened near the bottom surface of the impeller, and is provided at a plurality of locations in the circumferential direction of the impeller to exhaust regardless of the installation posture of the centrifugal pump. I like it.

  In the liquid supply apparatus according to the present invention, the centrifugal pump is disposed in a tank that stores the liquid to be sent out by the centrifugal pump, so that even if the pressurized liquid leaks through the exhaust port. The leakage is not a problem because it only returns to the tank.

  Hereinafter, the present invention will be described with reference to an embodiment shown in the accompanying drawings. As shown in FIG. 1, a rotor in a pump chamber surrounded by a pump case 11 having a suction port 12 and a discharge port 13 and a partition plate 16 is provided. An impeller 14 having a magnet 15 is disposed. An open-type impeller 14 shown in the figure, in which a plurality of blades 14a are provided radially from the rotation center portion to the outer edge portion and even the rear surface Ud 14b is integrated, has a shaft 17 fixed to the center of the partition plate 16. On the other hand, the bearing 18 made of slidable resin such as carbon-containing PPS resin and a pair of thrust bearings 19a and 19b are supported rotatably around the axis.

  The partition plate 16 includes a pump unit 20 that houses an impeller 14 provided with a rotor magnet 15 in a pump chamber, and a magnetic drive unit 21 that includes a stator 21a and a drive circuit 21b that supplies current to the coils of the stator 21a. Partitioning.

  Here, at the center of the impeller 14, a plurality of annular flow paths 22 that connect between the front side and the back side (partition plate 16 side) on which the blades 14a are provided are provided at appropriate intervals. Yes.

  When the impeller 14 is rotated by driving by the magnetic drive unit 21, a liquid is introduced from the suction port 12 because the central portion of the impeller 14 becomes negative pressure, and is applied along the blade 14 a by the centrifugal force of the impeller 14. While being pressed, it is sent to the outer edge of the impeller 14 and discharged from the discharge port 13.

  At this time, if gas (bubbles) is mixed in the liquid, bubbles with a specific gravity lower than that of the liquid gather at the center of rotation due to centrifugal force, and the bubbles are further combined to form a larger gas lump as the flow rate decreases. The pressured liquid flows from the outer edge of the impeller 14 into the sub-flow path 24 on the back surface side of the impeller 14, and is ejected to the gas reservoir through the annular flow path 22 to crush bubbles. The flow rate of the liquid is increased by this pulverization, and the reduced bubbles are guided to the outer edge of the impeller 14 together with the liquid.

  At the outer edge, a volute is formed on the inner wall of the pump case 11 on the same surface as the liquid flow direction of the outer surface of the impeller 14 toward the discharge port 13 with a gentle curved surface toward the discharge port 13. Since the liquid flow at the outer edge is a laminar flow in the normal direction of rotation, the liquid containing bubbles is guided from the outer edge to the volute and heads toward the discharge port 13 to the flow direction. Bubbles do not go to the sub-channel 24 having an angle of 90 ° or more.

  In addition, it is preferable that the entrance width | variety of the subchannel 24 shall be about 0.2 mm-0.7 mm. If it is narrower than this value, the supply of liquid to the sub-channel 24 is hindered, and if it is too wide, bubbles tend to enter the sub-channel 24. Further, it is preferable to keep the sub-channel 24 as far as possible except for the entrance portion in order to reduce pressure loss.

  As described above, the sub-flow path 24 is also a space for storing pressurized liquid for discharging liquid mixed with gas. As described above, the gas flows into the space before the pump is driven. If it enters, since it cannot supply the liquid which blows off through the said annular flow path 22 and grind | pulverizes a bubble, it will be in the state of what is called an air lock and will be inoperable.

  However, in the centrifugal pump according to the present invention, the exhaust port 23 is provided at a place where the pump casing 11 and the partition plate 16 are joined on the outer peripheral side of the impeller 14. The exhaust port 23 that connects the vicinity of the entrance of the sub-channel 24 and the space outside the pump casing 11 discharges air bubbles that remain in the sub-channel 24, and therefore, Since the liquid reaching the annular flow path 22 through the sub flow path 24 can be secured, the liquid mixed with gas can be discharged without causing an air lock.

  The exhaust port 23 preferably has a cross-sectional area with a diameter of about 0.2 mm to 1.0 mm. If it is too narrow, the bubbles will not be discharged, and if it is too wide, the performance degradation will increase.

  As shown in FIG. 2, the exhaust port 23 may be provided in a portion near the bottom where the rotor magnet 15 of the impeller 14 is located. Further, by providing the exhaust ports 23 at several locations in the circumferential direction of the impeller, it is possible to discharge bubbles regardless of the mounting posture of the centrifugal pump. In addition, the liquid pressurized through the exhaust port 23 may leak to the outside, but this point may cause a problem by immersing the centrifugal pump itself in a tank in which the liquid to be sent out is stored. There will be nothing.

  That is, FIG. 3 shows a case where the centrifugal pump 6 according to the present invention is applied to a liquid cooling device. In FIG. 3, reference numeral 3 denotes a heat-generating component 1 mounted on the substrate 2 that is cooled by heat exchange with the coolant. The cooler 4 is a radiator that removes heat from the coolant, and 5 is a reserve tank that stores the coolant. The reserve tank 5, the cooler 3, and the radiator 4 are connected by a circulation path 7. A centrifugal pump 6 for sending the coolant to the cooler 3 is immersed in the coolant in the reserve tank 5, and the coolant sent by the centrifugal pump 6 is reserved from the cooler 3 via the radiator 4. Return to tank 5.

  Thus, since the entire centrifugal pump 6 for sending out the coolant is arranged in the coolant to be sent out, even if the pressurized liquid (coolant) leaks from the exhaust port 23, the reserve tank 5 Since only the cooling liquid returns to the inside, the leakage from the exhaust port 23 does not cause a problem.

It is sectional drawing which shows an example of embodiment of this invention. It is sectional drawing which shows the other example same as the above. It is a piping diagram of the liquid supply apparatus using the centrifugal pump same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Pump casing 12 Suction port 13 Discharge port 14 Impeller 16 Partition plate 22 Ring flow path 23 Exhaust port 24 Subflow path

Claims (3)

  A centrifugal pump that includes an impeller that is driven to rotate, pressurizes the liquid sucked from the suction port by the rotation of the impeller, and sends the liquid from the discharge port by centrifugal force. A centrifugal pump characterized in that a space between the outer wall and the outer wall communicates with a space outside the pump chamber through an exhaust port formed in the outer wall.   The centrifugal pump according to claim 1, wherein the exhaust port has one end opened in the vicinity of the bottom surface of the impeller and is provided at a plurality of locations in the circumferential direction of the impeller.   3. The liquid supply apparatus according to claim 1, wherein the centrifugal pump according to claim 1 or 2 is disposed in a tank storing a liquid to be delivered by the centrifugal pump.

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