JP2015055164A - Drain pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drain pump capable of reducing the sound pressure level of paddling sound caused by a pump rotor even in a case of low lifting, and enabling its downsizing.SOLUTION: A drain pump comprises: a plurality of skewer-like projection pieces 20ai (i=1 to 72) in which a pump rotor 12 constitutes an agitator; and a truncated cone-like support 12A having a shaft part 12B, inserted into a suction port 10a, at a lower end, and formed integrally with the lower end of the projection piece 20ai. In the drain pump, between the outer peripheral surface of the support 12A of the pump rotor 12 and the inner peripheral surface of the side wall of a lower housing 10, a clearance CL of 1 mm or more and 2 mm or less is formed.

Description

  The present invention relates to a drain pump having a pump rotor.

  In the air conditioner, a drain pump that discharges water or the like accumulated in the drain pan to the outside is provided. As shown in Patent Document 1, for example, the drain pump includes a lower housing (referred to as a casing in Patent Document 1) having a suction pipe that forms a suction port at the lower end of the center portion, and a rotor housing in the lower housing. A rotor that is rotatably arranged in the chamber, an upper housing that forms a rotor housing chamber (pump chamber) together with an inner peripheral portion of the lower housing, and is supported by the upper housing And a drive motor for driving the rotor as main elements.

  The inner peripheral portion of the lower housing is formed so as to spread in a funnel shape with the suction port as the center. One end of the suction port is arranged in the drain pan. Thereby, when the rotor mentioned later is made into an operation state, the water etc. in a drain pan are introduced into a rotor storage chamber. In addition, a discharge port portion extends along the direction orthogonal to the central axis of the suction port on the side wall of the lower housing. The discharge port for discharging the fluid in the rotor housing chamber includes a small diameter portion and a large diameter portion communicating with the rotor housing chamber of the lower housing.

  The cylindrical portion formed at the lower end of the upper housing is connected to the open end of the upper end portion of the lower housing via an O-ring. At the outer peripheral edge of the bottom plate of the upper housing, for example, as shown in Patent Document 1, a cylindrical partition wall projects toward the bottom wall of the lower housing in order to reduce noise caused by bubbles at the discharge port portion. May be provided. Thereby, a gap is formed between the side wall of the lower housing and the partition wall. Further, the fluid is guided to the discharge port through the annular gap. In that case, since the bubble which exists in the upper periphery of a pump chamber is suppressed by the above-mentioned partition wall being guided to a discharge port part, the noise by the bubble in a discharge port part is reduced.

  A bearing portion that rotatably supports the output shaft of the driving motor is formed at the center of the flat portion of the cylindrical portion of the upper housing so as to face the through hole of the flat portion. The through hole of the flat portion described above communicates with the rotor accommodating chamber.

  The rotor is composed of a truncated cone part having a shaft part inserted into the suction port at the lower end and a plurality of pins formed integrally with the truncated cone part.

  A hub member to which the output shaft of the drive motor is connected is disposed in the hole at the center of the truncated cone portion. Each of the plurality of pins has a regular quadrangular prism shape. As shown in FIG. 8 in Patent Document 1, each pin is provided along the central axis of the hub member on the annular surface of the truncated cone portion adjacent to each communication hole. The plurality of pins are arranged at predetermined intervals vertically and horizontally around the hub member. By arranging a plurality of pins in this way, the occurrence of cavitation is suppressed, so that noise caused by cavitation is reduced.

  In such a configuration, when the rotor is rotated, for example, when the drain pump has a high head and the discharge amount decreases, a high back pressure from the discharge port side acts on the fluid sucked from the suction port. The air layer contained in the sucked fluid is retained in the vicinity of the hub member of the rotor which is directly above the above-described hole and inside the plurality of innermost pins.

  On the other hand, when the rotor is rotated, for example, when the drain pump has a low lift and the discharge amount increases, the back pressure from the discharge port side with respect to the fluid sucked from the suction port is higher than that at the high lift. As a result, the air layer contained in the sucked fluid spreads upward from the position directly above the hole. That is, the gas-liquid interface, which is the interface between the liquid and air, moves toward a plurality of pins located on the outermost side. Thereby, an air field is expanded.

Japanese Patent No. 4680922

  As described above, in the drain pump, when the drain pump has a low head, the air region expands, so the air layer and the fluid liquid layer are mixed, and the vicinity of the pin where the bubbles are located relatively outside of the plurality of pins May occur. In such a case, the relative speed between the plurality of pins located relatively outside and the gas-liquid boundary surface increases, and the contact area between the plurality of pins and the gas-liquid boundary surface increases, so the so-called water scraping sound is generated by the drain pump. With the problem that becomes larger than when it becomes a high head. In the operation of the drain pump, when the head is set to a low head in order to ensure the discharge amount, this problem becomes harmful as a commercial value, so it is desired to reduce the sound pressure level of the watering noise.

  Further, the drain pump is required to be downsized in accordance with downsizing of the air conditioner. However, when a cylindrical partition wall is provided on the outer peripheral edge portion of the bottom plate of the upper housing in order to reduce noise caused by bubbles at the discharge port portion as shown in Patent Document 1 described above, the drain pump can be downsized. Is not easy.

  In view of the above problems, the present invention is a drain pump having a pump rotor, which can reduce the sound pressure level of watering noise caused by the pump rotor, even in the case of a low head. An object of the present invention is to provide a drain pump capable of reducing the size of the drain pump.

  In order to achieve the above-described object, a drain pump according to the present invention is rotatably disposed in a pump housing having a suction port and a discharge port, and a rotor housing chamber in the pump housing, and is rotated by a rotation driving means. And a pump rotor having a support plate on which a plurality of projecting pieces for applying centrifugal force to the fluid introduced through the suction port are formed at predetermined intervals, and the plurality of projecting pieces face the suction port. A gap between the outer peripheral surface of the support plate of the pump rotor and the inner peripheral surface of the pump housing, forming at least a second array that is similar to the first array serving as a reference from the center of the section toward the periphery Is set to 1 mm or more and 2 mm or less.

  According to the drain pump of the present invention, the plurality of projecting pieces are arranged vertically and horizontally on the support plate so that the number per unit area increases from the center of the rotor accommodating portion facing the suction port toward the periphery. Since the gap between the outer peripheral surface of the support plate and the inner peripheral surface of the pump housing is set to 1 mm or more and 2 mm or less, the sound pressure level of the water scraping noise caused by the pump rotor is reduced even in the case of a low head In addition, the drain pump can be downsized.

It is sectional drawing which shows an example of the drain pump which concerns on this invention. It is a fragmentary sectional view shown along the II-II line in FIG. It is the elements on larger scale in FIG. It is the elements on larger scale in FIG. It is a characteristic view which shows the characteristic of the sound pressure level of the noise in an example of the drain pump which concerns on this invention. It is a characteristic view which shows the characteristic of the sound pressure level of the noise in an example of the drain pump which concerns on this invention, and a comparative example.

  FIG. 2 shows a configuration of an example of a drain pump according to the present invention.

  In FIG. 2, the drain pump includes a lower housing 10 having a suction pipe forming a suction port 10 a at the lower end of the central portion, a pump rotor 12 rotatably disposed in the lower housing 10, and an inner periphery of the lower housing 10. The upper housing 14 which forms a rotor accommodating chamber together with the portion, and a drive motor 16 which is disposed in the upper housing 14 and drives the pump rotor 12 are mainly included.

  One end of the suction port 10a of the lower housing 10 is disposed, for example, in a drain pan (not shown).

  The inner peripheral portion of the lower housing 10 is formed so as to spread in a funnel shape with the suction port 10a as a center. In addition, a discharge port portion extends on the side wall of the lower housing 10 along a direction orthogonal to the central axis of the suction port 10a. The discharge port portion includes a small diameter portion 10 b and a large diameter portion 10 c that communicate with the rotor housing chamber of the lower housing 10.

  A cylindrical portion formed at the lower end of the upper housing 14 is connected to the open end of the upper end portion of the lower housing 10 via an O-ring 18. A bearing portion (not shown) that rotatably supports the output shaft 16S of the drive motor 16 is formed integrally with the through hole 14a at the center portion of the flat portion 14W of the cylindrical portion of the upper housing 14. ing. The bearing portion is disposed on an axis common to the center axis of the output shaft 16 </ b> S of the drive motor 16. An output shaft 16S and a hub member 22 of the pump rotor 12, which will be described later, are inserted into a through hole 14a communicating with a rotor accommodating chamber (hereinafter also referred to as a pump chamber). The bearing portion includes a seal member that seals the outer peripheral portion of the output shaft 16S on the inner side. Therefore, the pump housing is formed by the lower housing 10 and the upper housing 14.

  The drive motor 16 is, for example, a flat DC brushless motor and is supported on the upper housing 14. The rotation speed of the output shaft 16S of the drive motor 16 is controlled by a control board (not shown) according to the discharge flow rate. Moreover, although illustration is abbreviate | omitted, the upper housing 14 has an air | atmosphere communication hole in several places. The drive motor 16 is not limited to such an example, and may be an AC motor capable of controlling the rotation speed, for example, a take-up motor with an encoder.

  As shown in FIGS. 1 and 2, the pump rotor 12 includes a plurality of skewer-shaped protrusions 20ai (i = 1 to 72) that constitute a stirring body that imparts centrifugal force to the fluid, and a suction port 10a. It has a shaft portion 12B to be inserted at its lower end and includes a truncated cone-shaped support 12A formed integrally with the lower end of the projection piece 20ai.

  The support body 12A is formed of, for example, a resin material and has a shaft portion 12B inserted into the suction port 10a at the lower end. As shown in FIG. 1, a hub member 22 to which the output shaft 16S of the drive motor 16 is connected is disposed in the central through hole 12a of the support 12A having a diameter of about 41 mm. The hub member 22 is integrally formed on a central axis common to the central axis of the shaft portion 12B, and protrudes so as to penetrate the above-described through hole 14a. That is, the hub member 22 is formed substantially perpendicular to the support surface of the support 12A. The hub member 22 is connected to the periphery of the through hole 12a by connecting pieces 12R1 to 12R4. Each of the connecting pieces 12R1 to 12R4 branches into four places at equal intervals along the circumferential direction, and is integrally formed at the end of the shaft portion 12B.

  The 72 projecting pieces 20ai are formed of, for example, a resin material integrally with the support 12A and have a rectangular cross section of about 1.8 mm square. The protruding pieces 20ai are formed vertically and horizontally at predetermined intervals around the through hole 12a of the support 12A. The protrusions 20ai are arranged at a position closest to the through hole 12a, for example, as shown in an enlarged view in FIG. 1, for example, with a predetermined rectangular distance Db and a reference rectangular shape having seven lines on one side. Contains one sequence. Further, the second array is formed like a similar shape surrounding the first array. The second array is composed of seven protrusion pieces 20ai on one side facing each protrusion piece 20ai in the first array which is a reference at a predetermined interval Db and Da in a direction away from the through hole 12a. At that time, in the second array, the two protrusion pieces 20ai facing the protrusion pieces 20ai at the corners of each side in the reference first array are positioned on the outermost circumference of the support 12A. Is formed. Further, the third array has a predetermined distance Db between each side of the second array and the outermost periphery of the support 12A in a direction away from the through hole 12a with respect to each side of the second array. And it is formed in parallel with Da. On each side of the third array, five protruding pieces 20ai are formed with a predetermined interval Db and Da. The predetermined distance Da between the adjacent protruding pieces 20ai is set to a value in the range from a value exceeding zero to about 1.5 mm, for example, as shown in an enlarged manner in FIG. The interval Da is preferably set to about 1.5 mm. The intervals Db and Da may be the same or different from each other. Further, the distances Db and Da may be set so as to gradually decrease from the inner edge to the outer edge of the support 12A.

  The length along the axis of each projection piece 20ai differs so that the uppermost end position of the projection piece 20ai is located on a common plane, and the length becomes shorter toward the outer peripheral edge of the support plate 12. The average length along the axis of each projection piece 20ai is, for example, 5 to 10 mm. As shown in FIG. 2, a predetermined gap GA is formed between the uppermost end of the protruding piece 20ai and the surface of the flat portion 14W of the upper housing 14 facing the pump chamber. A predetermined gap CL is formed between the outer peripheral surface of the support 12 </ b> A of the pump rotor 12 and the inner peripheral surface of the side wall of the lower housing 10. The dimension of the gap CL is set to 1 mm or more and 2 mm or less, preferably 1 mm or more and 1.5 mm or less.

  The reference first array is formed in a rectangular shape, but is not necessarily formed in this manner. For example, the reference first array is formed in a circular shape and the second array is formed. The third array may be formed at predetermined equal intervals so as to have a similar shape following the reference first array.

  When the dimension of the clearance CL is set to be less than 1 mm, the outer periphery of the support 12A of the pump rotor 12 may come into contact with the inner periphery of the side wall of the lower housing 10 during operation. The above is appropriate. Further, when the size of the gap CL exceeds 2 mm, as will be described later, the sound pressure level of the water scraping abruptly rises at a low head, so that the size of the gap CL is suitably 2 mm or less. Accordingly, the dimension of the gap CL is set in the range of 1 mm or more and 2 mm or less. Note that the value of the gap GA is set to be equal to or less than the value of the gap CL.

  As a result, when the drive motor 16 is in an operating state, the fluid sucked from the suction port 10a along the direction indicated by the arrow due to the centrifugal force generated by the rotating pump rotor 12 flows into the inner peripheral portion of the lower housing 10 and The space formed by the inner peripheral portion of the lower end of the upper housing 14, that is, the rotor housing chamber is guided through the through hole 12a, and discharged to the outside along the direction indicated by the arrow through the small diameter portion 10b and the large diameter portion 10c. The The rotation direction of the pump rotor 12 by the drive motor 16 may be either a clockwise direction or a counterclockwise direction.

  In such a configuration, when the rotational speed of the pump rotor 12 is controlled by controlling the rotational speed of the output shaft of the drive motor 16, for example, when the discharge amount is a low head of about 400 cc / min, As shown in FIG. 2, the liquid enters the annular liquid layer, which is the fluid sucked through the suction port 10a and the through-hole 12a, and enters the air-liquid boundary surface BP through the air communication hole and the through-hole 14a. Air phase APH is formed by air. A liquid phase LPH is formed around the air phase APH via the gas-liquid interface BP. The gas-liquid interface BP is formed by a balance between the centrifugal force generated by the pump rotor 12 during operation, the hydraulic head pressure from the discharge port, and the reaction force from the inner peripheral portion of the lower housing 10 caused by the centrifugal force.

  Thereby, the liquid in the rotor housing chamber is guided by centrifugal force to the inner peripheral portion of the lower housing 10 and the inner peripheral portion of the lower end of the upper housing 14, and in the direction indicated by the arrow F through the small diameter portion 10b and the large diameter portion 10c. Along the outside. Therefore, when the dimension of the gap CL between the outer peripheral surface of the support 12A of the pump rotor 12 and the inner peripheral surface of the side wall of the lower housing 10 is set to 1 mm or more and 2 mm or less, the pump rotor 12 When rotated in the direction indicated by the arrow R, as shown in an enlarged view in FIG. 3 and FIG. 4, the high-pressure region HP indicated by diagonal lines is formed in the liquid phase, so that the liquid phase increases and the gas-liquid boundary surface BP is shifted to the through-hole 12a side. As a result, the number of the projecting pieces 20ai of the pump rotor 12 decreases toward the through hole 12a, and the peripheral speed of the pump rotor 12 decreases, so that the sound pressure level of the water scraping sound is reduced by reducing the amount of bubbles. .

  FIG. 5 shows the effect of reducing the sound pressure level in the gap (clearance) CL using the example shown in FIGS. 1 and 2 (hereinafter also referred to as drain pump A) as an example of the drain pump according to the present invention. Indicates the verified result.

  The drain pump A includes a pump rotor 12 having a support plate 12A having a diameter of about 41 mm. The support plate 12A has 72 projection pieces 20ai of 1.8 mm square. The distance Da between the adjacent protrusions 20ai is set to 1.5 mm.

  The method of such an experiment is to change the above-mentioned clearance (clearance) CL from 0.5 mm to 3 mm in the drain pump A in which the discharge amount is set to about 400 cc / min so as to achieve a low head with a head pressure of about 150 mm. The sound generated in each gap was measured by mounting the pump rotors with different diameters. The generated sound was measured by the A characteristic with a noise meter (Ono Sokki Co., Ltd .: LA5120) in an anechoic box about 500 mm away from the discharge port.

  FIG. 5 shows a curve La in which the sound pressure level (logarithmic value) (dB) is taken on the vertical axis and the clearance CL (mm) is taken on the horizontal axis, and changes in the sound pressure level in the drain pump A are shown.

  As apparent from the curve La in FIG. 5, it was confirmed that the sound pressure level suddenly increased when the gap CL exceeded 2 mm. Thus, it was confirmed that the sound pressure level is reduced at the low head when the gap CL is less than 1 mm to less than 2 mm.

  FIG. 6 shows the result of comparative verification of the effect of reducing the sound pressure level using the above-described drain pump A and the conventional drain pump (also referred to as drain pump B) shown in Patent Document 1 as a comparative example. . As described above, the drain pump A includes the pump rotor 12 having the support plate 12A having a diameter of about 41 mm. The support plate 12A has 72 projection pieces 20ai of 1.8 mm square. The distance Da between the adjacent protrusions 20ai is set to 1.5 mm. Moreover, the above-mentioned clearance (clearance) CL is set to 1.5 mm. The drain pump B includes a rotor 23 having a diameter of about 41 mm as shown in FIG. 3 and FIG. The rotor 23 has 72 pins 43 and a plurality of communication holes 44. Unlike the drain pump A, the drain pump B includes a cylindrical partition wall 37 between the inner peripheral portion of the casing 20 and the outer peripheral portion of the rotor 23 thereof. Thereby, the dimension of the clearance gap between the inner peripheral part of the casing 20 and the outer peripheral part of the rotor 23 is set to the big dimension exceeding 1.5 mm.

  Such an experimental method is such that the drain pump A and the drain pump B each discharge a predetermined discharge amount, and the position of one end of the hose connected to the discharge port of the drain pump A and the drain pump B is changed. The sound generated from the vicinity of the discharge port was measured by a sound level meter while changing the value. The generated sound was measured with the A characteristic by a noise meter (ONO SOKKI Co., Ltd .: LA5120) in an anechoic box about 500 mm away from the discharge port. At that time, one end of the hose connected to the discharge port portion of the drain pump A and the drain pump B is gradually moved upward from the position of the discharge port portion to a position of 1.125 m height from the position of 0.1 m height. Raised.

  In FIG. 6, the sound pressure level (logarithmic value) (dB) is taken on the vertical axis, the lift (mm) is taken on the horizontal axis, the curve Lb showing the change in the sound pressure level in the drain pump A, and the drain pump B The curve Lc which shows the change of a sound pressure level is shown. When the head is 1125 mm, the sound pressure level is 0 (zero) dB.

  As a result of the experiment, as is clear from the curve Lb, the sound pressure level of the noise in the drain pump A is lower than the sound pressure level of the noise in the drain pump B at the entire head, and the noise in the drain pump A is improved. It was confirmed that In particular, as is apparent from the curve Lb in FIG. 6, for example, the sound pressure level of the noise in the drain pump A is the sound pressure of the drain pump B in the range where the head in the curve Lb is 100 mm to 500 mm, that is, in the range of the low head. Since it is reduced by 2 dB or more as compared with the level, it was proved that there is an effect of noise improvement by setting the clearance (clearance) CL in the drain pump A to 1.5 mm at the low head.

  Accordingly, in the drain pump A, noise can be improved without providing the cylindrical partition wall 37 as in the drain pump B, so that the drain pump A can be downsized.

10 Lower housing 12 Pump rotor 12A Support body 14 Upper housing 20ai Projection piece CL Clearance

Claims (4)

A pump housing having a suction port and a discharge port;
A plurality of projecting pieces are formed at predetermined intervals so as to be able to rotate in the rotor housing chamber of the pump housing and apply centrifugal force to the fluid introduced through the suction port when being rotated by the rotation driving means. A pump rotor having a support plate
The plurality of projecting pieces form at least a second array that is similar to the first array serving as a reference from the center of the rotor accommodating portion facing the suction port toward the periphery, and supports the pump rotor A drain pump, wherein a gap between an outer peripheral surface of the plate and an inner peripheral surface of the pump housing is set to 1 mm or more and 2 mm or less.   The drain pump according to claim 1, wherein the leading ends of the plurality of projecting pieces are on a common plane.   2. The drain pump according to claim 1, wherein the protruding piece has a rectangular cross section, and the predetermined interval between the plurality of adjacent protruding pieces is set to be more than zero and 1.5 mm or less.   The clearance between the leading edge of the plurality of protruding pieces and the wall surface forming the rotor accommodating chamber facing the leading edge of the protruding pieces is an outer peripheral surface of the support plate of the pump rotor and an inner peripheral surface of the pump housing. The drain pump according to claim 1, wherein the drain pump is smaller than a gap between the drain pumps.

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