CN111692126A

CN111692126A - Centrifugal pump

Info

Publication number: CN111692126A
Application number: CN202010176151.8A
Authority: CN
Inventors: 铃木敬升; 本田义彦
Original assignee: Aisan Industry Co Ltd
Current assignee: Aisan Industry Co Ltd
Priority date: 2019-03-15
Filing date: 2020-03-13
Publication date: 2020-09-22
Also published as: JP2020148169A; US20200291954A1

Abstract

The invention provides a centrifugal pump, which ensures a larger inlet area under the condition of not reducing the number of blades and improves the pump efficiency. The impeller (140) has: a disc-shaped base (144); a 1 st vane (146) that extends outward from the radially inner side of the base (144) on the front surface of the base (144) that is the surface facing the suction passage; and a 2 nd blade (148) extending from the radially inner side to the radially outer side, the 2 nd blade (148) having a length in the radial direction equal to that of the 1 st blade (146) and having: a low blade section (156) located radially inward and formed to have a height from the base section lower than that of the 1 st blade (146) when comparing portions that are equidistant from the center of the base section (144) with each other; and a high blade section (158) located radially outward and formed to have the same height from the base as the 1 st blade (146).

Description

Centrifugal pump

Technical Field

The technology disclosed herein relates to a centrifugal pump.

Background

In a general centrifugal pump, first, a fluid sucked from a suction inlet (suction passage) is guided to a central portion of an impeller. The pressure is fed by the rotation of a plurality of blades formed on the front surface of the impeller on the side opposite to the motor, and the pressure is discharged from a discharge port (discharge passage).

However, in order to improve the pump efficiency of the centrifugal pump, various improvements have been made in the shape of the centrifugal blade of the impeller. For example, there is a centrifugal pump including an impeller having a 1 st blade extending from a central portion toward an outer end portion in a radial direction of the impeller and a 2 nd blade having a length shorter than that of the 1 st blade and formed in the vicinity of the end portion on the outer side in the radial direction. That is, there is a structure in which a portion near the impeller center portion of the 2 nd blade is missing. With this configuration, the inlet area can be secured large without reducing the number of vanes, and the pump efficiency can be improved.

Patent document 1: japanese laid-open patent publication No. 11-218097

Disclosure of Invention

Problems to be solved by the invention

In the configuration in which the portion of the 2 nd blade near the impeller center portion is missing as in the above-described technique, the inlet area of the impeller can be ensured to be large. However, since the 2 nd blade is missing in the vicinity of the impeller center portion, the fluid sucked into the impeller center portion is mainly received by the 1 st blade due to the rotation of the centrifugal pump, and an imbalance in the pressure feed amount occurs between the 1 st blade and the 2 nd blade. That is, the pressure feed amount of the 2 nd vane becomes smaller than the pressure feed amount of the 1 st vane.

In view of the above problems, the present invention aims to improve the shape of the 2 nd vane, thereby improving the imbalance of the pressure feed rate and further improving the pump efficiency.

Means for solving the problems

In order to solve the above problem, the centrifugal pump disclosed in the present specification adopts the following configuration.

The technical means of 1 is a centrifugal pump comprising: a housing having a discharge passage and a suction passage formed therein; and an impeller that is disposed in the housing so as to be coaxial with the suction passage, wherein the impeller includes: a base portion of a disc shape; a 1 st vane extending outward from a radially inner side of the base portion on a front surface of the base portion, the front surface being a surface facing the suction passage; and a 2 nd blade also extending on the front surface from the radially inner side to the radially outer side of the base portion, the 2 nd blade having a length in the radial direction that is the same as that of the 1 st blade and having: a low blade portion located radially inward, and formed to have a height from the base portion lower than that of the 1 st blade when comparing portions having equal distances from the center of the base portion with each other; and a high blade portion located at an outer side in the radial direction, and also formed to have a height from the base portion equal to that of the 1 st blade when comparing portions having equal distances from the center of the base portion with each other.

According to the above-described aspect 1, it is possible to suppress the amount of fluid that is pressure-fed by the 1 st blade and the 2 nd blade from becoming uneven while ensuring a large inlet area of the impeller. Therefore, the pump efficiency can be improved as compared with the conventional centrifugal pump.

The centrifugal pump according to claim 2 is the centrifugal pump according to claim 1, wherein a height of the low vane portions from the base portion gradually increases from the radially inner side toward the radially outer side.

According to the above-described aspect 2, the impeller can be easily molded.

The 3 rd aspect is the centrifugal pump according to the 1 st aspect, wherein a height of the 2 nd blade from the base portion increases stepwise at a boundary portion between the low blade portion and the high blade portion.

According to the above-described aspect 3, the height of the low blade portion can be sufficiently reduced over the entire radial length thereof. Therefore, the pump efficiency can be further improved as compared with the above-described solution 1.

The 4 th aspect is the centrifugal pump according to any one of the 1 st to 3 rd aspects, wherein the 4 th aspect includes: a flat plate portion formed on the radially outer side of the base portion and flat; and a protrusion portion having an inclined surface which is formed continuously from an inner end of the flat plate portion toward the radial direction inner side, and which is formed only in the protrusion portion as the height increases toward the radial direction inner side.

According to the above-described aspect 4, the height of the portion that is a part of the 2 nd blade located inside the protruding portion and located radially inward is lower than the height of the 1 st blade, and therefore the inlet area of the impeller can be ensured to be large. In addition, in the flat plate portion where the pressure of the fluid becomes high, the 2 nd blade has the same height as the 1 st blade, and therefore, the fluid can be sufficiently pressurized and conveyed. Therefore, even in a centrifugal pump in which the base of the impeller has a projection, the pump efficiency can be improved.

The 5 th aspect is the centrifugal pump according to the 4 th aspect, wherein one of the 1 st blade and the 2 nd blade includes: a thin blade portion located on the radially inner side, formed to have a thickness thinner than that of the other of the 1 st blade and the 2 nd blade when comparing portions that are equidistant from the center of the base portion with each other; and a thick blade portion located radially outward of the base portion, and also formed to have the same thickness as that of the other when comparing portions that are equidistant from the center of the base portion with each other.

According to the above-described aspect 5, since one of the 1 st blade and the 2 nd blade has the thin blade portion, the inlet area of the impeller can be secured larger than that of the above-described aspect 4. Therefore, the pump efficiency can be further improved as compared with the case of claim 4.

The 6 th aspect is the centrifugal pump of the 5 th aspect, wherein the thin blade portion is formed only in the protruding portion.

According to the above-described aspect 6, since the thickness of the portion of one of the 1 st blade and the 2 nd blade, which is located inside the projection and is located radially inward, is thinner than the thickness of the other blade, the inlet area of the impeller can be ensured to be large. In the flat plate portion where the pressure of the fluid becomes high, the blade of one has the same thickness as that of the blade of the other. Therefore, even in a centrifugal pump having a protruding portion at the base of the impeller, the pump efficiency can be improved while suppressing a decrease in the strength of the vane.

The centrifugal pump according to claim 7 is the centrifugal pump according to any one of claims 1 to 6, wherein the plurality of the 1 st blades and the plurality of the 2 nd blades are arranged regularly.

According to claim 7, the plurality of the 1 st blades and the plurality of the 2 nd blades are regularly formed on the front surface of the base, and the fluid can be uniformly pressurized and conveyed.

The 8 th aspect is the centrifugal pump according to the 7 th aspect, wherein the 1 st blade and the 2 nd blade are alternately arranged.

According to claim 8, since the plurality of the 1 st blades and the plurality of the 2 nd blades are alternately formed on the front surface of the base, the fluid can be pressurized and conveyed more uniformly than in the centrifugal pump according to claim 7.

ADVANTAGEOUS EFFECTS OF INVENTION

The centrifugal pump disclosed in the specification can improve the pump efficiency by adopting the technical scheme.

Drawings

Fig. 1 is a sectional view showing a centrifugal pump of embodiment 1.

Fig. 2 is a perspective view of the impeller of the centrifugal pump shown in fig. 1.

Fig. 3 is a top view of the impeller of the centrifugal pump shown in fig. 1.

Fig. 4 is a cross-sectional view taken along line IV-IV of fig. 3.

Fig. 5 is a sectional view taken along line V-V of fig. 3.

Fig. 6 is a plan view of an impeller of a comparative example.

Fig. 7 is a perspective view of the impeller of embodiment 2.

Fig. 8 is a top view of the impeller shown in fig. 7.

Fig. 9 is a cross-sectional view taken along line IX-IX of fig. 8.

Fig. 10 is an X-X line sectional view of fig. 8.

Fig. 11 is a perspective view of the impeller of embodiment 3.

Fig. 12 is a top view of the impeller shown in fig. 11.

Fig. 13 is a cross-sectional view along line XIII-XIII of fig. 12.

Fig. 14 is a cross-sectional view taken along the line XIV-XIV of fig. 12.

Fig. 15 is a side view as viewed from the direction of arrow XV in fig. 12.

Fig. 16 is a side view as viewed from the direction of arrow XVI in fig. 12.

Description of the reference numerals

10. A centrifugal pump; 12. a motor; 16. a housing; 32. a suction passage; 34, a suction inlet; 38. an ejection passage; 140. 240, 340, an impeller; 144. 244, 344, main board (base); 146. 246, 346, 1 st blade; 148. 248, 348, 2 nd blade; 150. 250, 350, a flat plate portion; 152. 252, 352, projection; 154. 254, 354, inclined plane; 156. 256, 356, low blade portion; 158. 258, 358, high blade; 260. a thin blade portion; 262. a thick blade portion.

Detailed Description

Various embodiments of the centrifugal pump will be described below based on the drawings.

[ embodiment 1 ]

In embodiment 1, for example, a centrifugal pump is exemplified which is mounted on a vehicle such as an automobile and used as a purge pump for compensating for a purge amount from a suction tank to an intake passage of an internal combustion engine (engine).

(outline of centrifugal Pump 10)

Fig. 1 is a sectional view showing a centrifugal pump 10. For convenience of explanation, the right-hand XYZ rectangular coordinate system is introduced to determine the direction of the centrifugal pump 10. The Z-axis direction is set as the vertical direction, the upper direction is set as the + direction, and the lower direction is set as the-direction. The X-axis direction and the Y-axis direction are horizontal directions. The X-axis direction is set as the left-right direction, the right direction is set as the + direction, and the left direction is set as the-direction. The Y-axis direction is defined as the front-rear direction, the front direction is defined as the + direction, and the rear direction is defined as the-direction. However, these directions do not limit the arrangement direction of the centrifugal pump 10.

As shown in fig. 1, the centrifugal pump 10 includes a motor 12, an impeller 140 rotated by torque generated by the motor 12, and a casing 16 housing the motor 12 and the impeller 140. The motor 12 is a general brushless motor, and includes a hollow cylindrical rotor 18, a shaft portion 20 having a lower end coaxially inserted into a hollow portion of the rotor 18, and a stator 22 surrounding an outer periphery of the rotor 18. The rotor 18 is formed of a permanent magnet having a plurality of magnetic poles in the circumferential direction with respect to the axis of the shaft portion 20. The stator 22 includes a plurality of coils (not shown) that surround the outer periphery of the rotor 18 at positions separated from the rotor 18 by a predetermined distance.

The upper end of the shaft portion 20 is coaxially inserted into a center hole 142 of the impeller 140 (details of the impeller 140 will be described later). Thereby, the shaft portion 20 transmits the torque generated between the rotor 18 and the stator 22 to the impeller 140. The housing 16 includes a 1 st housing portion 24 and a 2 nd housing portion 26 both made of resin. The 1 st and 2

nd casing portions

24 and 26 form a pump chamber 28 for accommodating the impeller 140. The pump chamber 28 is a space in which the impeller 140 can rotate without interfering with the inner wall of the pump chamber 28. A cylindrical suction portion 30 protruding upward is formed in the case 1 portion 24. The suction passage 32 is formed in the suction portion 30. The suction port 34 is provided at an end of the suction passage 32 on the opposite side to the pump chamber 28. The suction passage 32 communicates the inside and the outside of the pump chamber 28 via the suction port 34. Further, the discharge portion 36 that protrudes in the tangential direction (rightward in fig. 1) of the outer periphery of the impeller 140 is formed in the case 1 portion 24. The discharge passage 38 is formed in the discharge portion 36. The discharge port 40 is provided at an end of the discharge passage 38 on the opposite side to the pump chamber 28. The discharge passage 38 communicates the inside and outside of the pump chamber 28 through the discharge port 40.

The

bearings

42 and 44 include well-known ball bearings, an outer ring is fixed by press-fitting into the case 2 portion 26, and an inner ring is fixed to the shaft portion 20. In other words, the

bearings

42 and 44 rotatably support the shaft 20.

A control unit 46 is housed in the lower end of the case 2 portion 26. The control unit 46 is connected to an external connector (not shown) connected to an external power source (for example, a battery mounted on a vehicle) via a lead wire. The control unit 46 supplies electric power supplied from an external power source to the stator 22.

(construction of impeller 140)

Next, the structure of the impeller 140 will be described in detail. Fig. 2 is a perspective view of the impeller 140, fig. 3 is a plan view of the impeller 140, fig. 4 is a sectional view taken along line IV-IV of fig. 3, and fig. 5 is a sectional view taken along line V-V. In fig. 2 and 3, the rotation direction of the impeller 140 is clockwise in plan view as indicated by an arrow R. The impeller 140 includes a substantially disc-shaped main plate 144, and a plurality of 1 st blades 146 and a plurality of 2 nd blades 148 formed on a front surface (i.e., an upper surface) of the main plate 144, which is a surface on the side opposite to the suction passage 32. The main plate 144 has a flat plate portion 150 on the radially outer side thereof, and a projecting portion 152 projecting upward on the inner side of the flat plate portion 150. The radially outer end of the protruding portion 152 is continuous from the inner end of the flat plate portion 150. The protrusion 152 has an inclined surface 154 (see fig. 4 and 5) whose height continuously increases toward the radially inner side. The main plate corresponds to the base of the present specification.

The 1 st blade 146 and the 2 nd blade 148 extend from the radially inner side of the main plate 144 to the radially outer side across the flat plate portion 150 and the protruding portion 152, respectively. The 1 st blade 146 and the 2 nd blade 148 have the same shape in plan view (see fig. 3), and have the same radial length. The radial length of the blade is, for example, a length obtained by subtracting the radius of the center hole 142 from the distance from the rotation center C (indicated by a point or a line in fig. 3, 4, and 5) of the main plate 144 to the point having the longest distance in a plan view. The 1 st blade 146 and the 2 nd blade 148 are alternately arranged at equal intervals. The 1 st blade 146 and the 2 nd blade 148 are vertically provided with respect to the main plate 144.

In a plan view of the impeller 140, radially inner ends of the 1 st blade 146 and the 2 nd blade 148 are formed so as to be offset to the front side (the side indicated by the arrow R) in the rotation direction of the impeller 140. On the other hand, the radially outer ends of the 1 st blade 146 and the 2 nd blade 148 are not offset before and after the impeller rotation direction. The radial center portion is inclined gradually from the front side to the rear side in the rotational direction.

As shown in fig. 4 and 5, the 2 nd blade 148 has a low blade portion 156 and a high blade portion 158. The low blade portion 156 is located radially inward of the main plate 144, and in a case where portions having equal distances from the center of the main plate 144 are compared with each other, the low blade portion 156 is formed to have a height from the main plate 144 lower than that of the 1 st blade 146 from the main plate 144. The high blade portions 158 are located radially outward of the low blade portions 156, and when comparing portions having equal distances from the center of the main plate 144, the high blade portions 158 are formed to have the same height from the main plate 144 as that of the 1 st blade 146 from the main plate 144. The low-blade portions 156 are located only at the protruding portion 152 of the main plate 144, and the high-blade portions 158 are formed astride the protruding portion 152 and the flat plate portion 150 of the main plate 144. That is, the boundary portion (the vicinity of the boundary line B shown in fig. 5) between the low-blade portion 156 and the high-blade portion 158 is located at the protruding portion 152. In embodiment 1, the height of the low blade portions 156 gradually increases toward the boundary with the high blade portions 158. In addition, in the present specification, "gradually increasing" includes both an increase in a straight line and an increase in a smooth curve. In the present specification, the height direction when "the height from the main plate" of the 1 st blade and the 2 nd blade is referred to means a direction perpendicular to a tangent line to a curved line corresponding to the inclined surface at each point on the curved line in a cross section shown when each blade is cut by a predetermined surface parallel to the rotation center C.

(action of centrifugal Pump 10)

Next, the operation of the centrifugal pump 10 will be described with reference to fig. 1. When power is supplied from the control unit 46 to the stator 22, a magnetic field is generated. Therefore, the rotor 18 rotates, and the shaft 20, the inner rings of the

bearings

42 and 44, and the impeller 140 rotate integrally with the rotation. By rotating the impeller 140, the fluid (purge gas) is sucked from the suction port 34 (see arrow Y1 in fig. 1) and is sent to the central portion of the impeller 140 through the suction passage 32. The fluid fed to the center of the impeller 140 is pressurized and fed clockwise by the 1 st blade 146 and the 2 nd blade 148 that rotate while flowing radially outward on the upper surface of the main plate 144. The fluid pressurized by the 1 st vane 146 and the 2 nd vane 148 is ejected from the ejection port 40 via the ejection passage 38 (see arrow Y2 in fig. 1).

(advantages of embodiment 1)

When the centrifugal pump 10 is operated, as described above, the fluid is pressurized and conveyed by the blades provided on the upper surface of the main plate 144 of the impeller 140. The more fluid that can be pressurized and delivered within a predetermined time, the higher the pump efficiency, and therefore, in order to improve the pump efficiency, it is considered that more blades are formed on the upper surface of the main plate 144 of the impeller 140. However, since the number of vanes is large, the space in the center of the impeller 140 in the pump chamber 28 is occupied by the vanes and becomes narrow. That is, the inlet area (also referred to as the opening area) of the impeller 140 is reduced. As a result, the frictional resistance generated at the interface between the fluid and the blades increases at the center of the impeller 140, and therefore it cannot be said that the pump efficiency can be improved by simply increasing the number of blades.

Therefore, in order to provide a larger number of blades on the upper surface of the main plate 144 of the impeller 140 while ensuring a larger inlet area, it is conceivable to form two types of blades having different radial lengths on the upper surface. More specifically, for example, in the comparative example shown in fig. 6, the end portion of one blade (for convenience of explanation, referred to as a short blade) is located radially outward of the end portion of the other blade (for convenience of explanation, referred to as a long blade). In the impeller thus configured, a larger inlet area can be ensured in the case where the same number of blades are formed.

However, the present inventors have found that there is room for further improvement in pump efficiency in the comparative example. That is, in the structure of the comparative example, since the inner end portion of the short vane is positioned radially outward of the long vane, the fluid positioned on the front side in the rotation direction of the short vane cannot be guided radially outward along the short vane in the vicinity of the center portion of the impeller (see the alternate long and short dashed line arrow Y3 in fig. 6). The fluid located on the front side in the rotation direction of the short blade reaches the long blade located adjacent to the rear side in the rotation direction of the short blade, and is finally pressure-fed by the long blade (see arrow Y4 in fig. 6). On the other hand, the fluid located on the front side in the rotation direction of the long blade in the vicinity of the center portion of the impeller is pressurized and conveyed by the long blade (see arrow Y5 in fig. 6). That is, the amount of fluid pressure-fed by the short blades is smaller than the amount of fluid pressure-fed by the long blades. Eliminating such imbalance in the amount of pressurized delivery between the long and short vanes can contribute to further improvement in pump efficiency.

The present inventors have also found that, in the vicinity of the central portion of the impeller 140, as shown in fig. 4 and 5, most of the fluid flows along the inclined surface 154, and therefore, even if the height of the blade is made low in the vicinity of the central portion, a slightly smaller amount of fluid can be fed under pressure than in the case where the height of the blade is made higher in the vicinity of the central portion. That is, in the impeller 140 of embodiment 1, the 1 st blade 146 and the 2 nd blade 148 have the same radial length. Further, the 2 nd blade 148 has: a low blade portion 156 located radially inward, the low blade portion 156 being formed to be lower in height from the main plate 144 than the 1 st blade 146 in height from the main plate 144 when comparing portions that are equidistant from the center of the main plate 144 with each other; and a high blade portion 158 located radially outward, the high blade portion 158 being formed to have a height from the main plate 144 equal to a height of the 1 st blade 146 from the main plate 144, also when comparing portions that are equidistant from the center of the main plate 144 with each other. With such a configuration, the impeller 140 can suppress the amount of fluid pressurized and fed by the 1 st blade 146 and the 2 nd blade 148 from becoming uneven while ensuring a large inlet area. Further, the pump efficiency of the centrifugal pump can be improved.

The height of the low blade portion 156 of the 2 nd blade 148 from the main plate 144 gradually increases from the radially inner side toward the radially outer side. This makes it possible to easily mold the impeller 140.

In the case where the main plate 144 includes the flat plate portion 150 and the protruding portion 152, the fluid flows along the inclined surface 154 without being sufficiently pressurized at the protruding portion 152, and has a speed in the rotation direction of the impeller 140 at a position outside the protruding portion 152, and the pressure increases. Therefore, the low blade portions 156 are formed only in the protruding portions 152, and the high blade portions 158 are disposed in the flat plate portion 150, whereby the fluid flowing through the flat plate portion 150 can be sufficiently pressurized and transported.

The 1 st blade 146 and the 2 nd blade 148 are alternately arranged. Therefore, the inlet area of the impeller 140 can be uniformly secured in the circumferential direction, and the amount of the fluid that is pressure-fed by each of the 1 st blade 146 and the 2 nd blade 148 can be suppressed from becoming uneven.

[ 2 nd embodiment ]

The centrifugal pump 10 according to embodiment 2 is configured in the same manner as embodiment 1, except that it includes an impeller 240 having a shape different from that of the impeller 140. Therefore, in embodiment 2, detailed description of the impeller 240 is omitted.

(construction of impeller 240)

The construction of the impeller 240 is explained in detail. Fig. 7 is a perspective view of the impeller 240, fig. 8 is a plan view of the impeller 240, fig. 9 is a sectional view taken along line IX-IX of fig. 8, and fig. 10 is a sectional view taken along line X-X of fig. 8. In fig. 7 and 8, the rotation direction of the impeller 240 is clockwise in plan view as indicated by an arrow R. The impeller 240 has a substantially circular plate-shaped main plate 244 and a plurality of 1 st blades 246 and a plurality of 2 nd blades 248 formed on the front surface (i.e., upper surface) of the main plate 244, respectively. Like the impeller 140 of embodiment 1, the main plate 244 has a flat plate portion 250 on the radially outer side thereof, and a projecting portion 252 projecting upward on the inner side of the flat plate portion 250. The protruding portion 252 has an inclined surface 254 (see fig. 7, 9, and 10) whose height continuously increases toward the radially inner side.

The 1 st blade 246 and the 2 nd blade 248 radially extend from the radially inner side to the radially outer side of the main plate 244 across the flat plate portion 250 and the protruding portion 252, respectively. The 1 st vane 246 and the 2 nd vane 248 have the same radial length in plan view. The 1 st blade 246 and the 2 nd blade 248 are alternately arranged at equal intervals. In addition, the 1 st blade 246 and the 2 nd blade 248 are vertically erected with respect to the main plate 244.

As clearly shown in fig. 8, in the plan view of the impeller 240, the radially inner ends of the main plates 244 of the 1 st blade 246 and the 2 nd blade 248 are formed so as not to deviate from each other in the front and rear in the impeller rotation direction (the side indicated by the arrow R). That is, the inlet angle of the 1 st vane 246 and the 2 nd vane 248 is 90 degrees. Further, the 1 st blade 246 and the 2 nd blade 248 are formed so that the radially outer end portions of the main plate 344 are not deviated in the front and rear of the impeller rotation direction (the side indicated by the arrow R). That is, the exit angle of the 1 st blade 246 and the 2 nd blade 248 is 90 degrees.

As best shown in fig. 7 and 8, the 1 st blade 246 has a thin blade portion 260 and a thick blade portion 262. The thin blade portion 260 is located radially inward of the main plate 244, and is formed to have a thickness thinner than that of the 2 nd blade 248 when comparing portions having equal distances from the center of the main plate 244 with each other. The thick blade portion 262 is located radially outward of the thin blade portion 260, and is formed to have the same thickness as the 2 nd blade 248 when comparing portions having the same distance from the center of the main plate 244 with each other. The thin blade portion 260 is located only at the protruding portion 252 of the main plate 244, and the thick blade portion 262 is formed astride the protruding portion 252 and the flat plate portion 250 of the main plate 244. That is, a boundary portion (the vicinity of a boundary line B shown in fig. 10) between the thin-blade portion 260 and the thick-blade portion 262 is located at the protruding portion 252. In the impeller 240 according to embodiment 2, the thickness of the 2 nd blade 248 is uniform over the entire length in the radial direction, and is, for example, 1 mm. On the other hand, the thickness of the thin blade portion 260 of the 1 st blade 246 is preferably about half of the thickness of the thick blade portion 262, for example, 0.5 mm.

As shown in fig. 7 and 10, the 2 nd blade 248 has a low blade portion 256 and a high blade portion 258. The low blade portion 256 is located radially inward of the main plate 244, and is formed to be lower in height from the main plate 244 than the 1 st blade 246 when comparing portions that are equidistant from the center of the main plate 244 with each other. The high blade portions 258 are located radially outward of the low blade portions 256, and when portions having equal distances from the center of the main plate 244 are compared with each other, the height from the main plate 244 is formed to be the same as the height of the 1 st blade 246 from the main plate 244. The low blade portions 256 are located only at the protruding portion 252 of the main plate 244, and the high blade portions 258 are formed astride the protruding portion 252 and the flat plate portion 250 of the main plate 244. That is, the boundary between the low blade portion 256 and the high blade portion 258 is located at the protruding portion 252. The height of the 2 nd blade 248 from the main plate 244 increases in a step-like manner at the boundary between the low blade portion 256 and the high blade portion 258. The phrase "increase in steps" means that, for example, in a cross section shown when the 2 nd blade 248 is cut by a predetermined plane parallel to the rotation center C, an angle formed by a boundary line B between the low blade portion 256 and the high blade portion 258 and a tangent line of the inclined surface 254 at a point where the boundary line B intersects the inclined surface 254 is about 90 degrees, for example, 85 degrees to 95 degrees. In embodiment 2, in the cross section shown when the impeller 240 is cut by a plane parallel to the rotation center C and passing through the center in the thickness direction of the 2 nd blade 248, that is, the cross section shown in fig. 10, the angle formed by the boundary line B and the tangent line of the inclined surface 254 at the point where the boundary line B intersects the inclined surface 254 is 90 degrees.

(advantages of embodiment 2)

In the impeller 240 of embodiment 2, the 1 st blade 246 and the 2 nd blade 248 have the same radial length. Further, the 2 nd blade 248 has: a low blade portion 256 located radially inward, the low blade portion 256 being formed to be lower in height from the main plate 244 than that of the 1 st blade 246 from the main plate 244 in a case where portions having equal distances from the center of the main plate 244 are compared with each other; and a high blade portion 258 positioned at a radially outer side, the high blade portion 258 being formed to have a height from the main plate 244 equal to a height from the main plate 244 of the 1 st blade 246, also in a case where portions at equal distances from the center of the main plate 244 are compared with each other. With such a configuration, the impeller 240 can suppress the variation in the amount of fluid pressurized and fed by the 1 st blade 246 and the 2 nd blade 248 while securing a large inlet area. Further, the pump efficiency of the centrifugal pump 10 can be improved.

The height of the 2 nd blade 248 from the main plate 244 increases stepwise at the boundary between the low blade portion 256 and the high blade portion 258. Therefore, the height of the low vane portions 256 can be sufficiently reduced over the entire radial length of the low vane portions 256.

In addition, the low blade portions 256 are formed only in the protruding portions 252. Therefore, the fluid flowing through the flat plate portion 250 can be sufficiently pressurized.

In addition, the 1 st blade 246 has a thin blade portion 260 and a thick blade portion 262. The thin blade portion 260 is located radially inward, and when comparing portions that are equidistant from the center of the main plate 244 with each other, the thickness thereof is formed thinner than the thickness of the 2 nd blade 248. The thick blade portion 262 is located radially outward, and is formed to have a thickness equal to that of the 2 nd blade 248 when the portions having equal distances from the center of the main plate 244 are also compared with each other. Therefore, the inlet area of the impeller 240 can be secured more than in the case where the thickness of the 1 st blade 246 is equal to the thickness of the 2 nd blade 248 over the entire radial length thereof.

In addition, the thin blade portion 260 is formed only in the protruding portion 252. Therefore, the strength of the blade can be ensured to be higher than in the case where the thickness of the blade is formed to be thin over the entire length in the radial direction.

The 1 st blade 246 and the 2 nd blade 248 are alternately arranged. Therefore, the inlet area of the impeller 240 can be uniformly secured in the circumferential direction, and the amount of the fluid that is pressure-fed by each of the 1 st blade 246 and the 2 nd blade 248 can be suppressed from becoming uneven.

[ embodiment 3 ]

The centrifugal pump 10 according to embodiment 3 is formed in the same manner as embodiment 1 except that it includes an impeller 340 having a shape different from that of the impeller 140 according to embodiment 1. Therefore, in embodiment 3, detailed description of the impeller 340 is omitted.

(construction of impeller 340)

The structure of the impeller 340 is explained in detail. Fig. 11 is a perspective view of the impeller 340, fig. 12 is a plan view of the impeller 340, fig. 13 is a sectional view taken along line XIII-XIII in fig. 12, fig. 14 is a sectional view taken along line XIV-XIV, fig. 15 is a side view taken along arrow XV, and fig. 16 is a side view taken along arrow XVI.

In fig. 11 and 12, the rotation direction of the impeller 340 is clockwise in plan view as indicated by an arrow R. The impeller 340 has a substantially circular plate-shaped main plate 344, and a plurality of 1 st blades 346 and a plurality of 2 nd blades 348 respectively formed on the front surface (i.e., the upper surface) of the main plate 344. Like the impeller 140 of embodiment 1, the main plate 344 includes a flat plate portion 350 on the radially outer side thereof, and a protruding portion 352 protruding upward on the inner side of the flat plate portion 350. The protruding portion 352 has an inclined surface 354 (see fig. 11) whose height continuously increases toward the radially inner side.

The 1 st blade 346 and the 2 nd blade 348 straddle the flat portion 350 and the protruding portion 352, respectively, and extend radially outward from the radially inner side of the main plate 344. The 1 st leaf 346 and the 2 nd leaf 348 have the same radial length in plan view. The 1 st and 2

nd blades

346 and 348 are alternately arranged at equal intervals.

As shown in fig. 12, the radially inner ends of the main plate 344 of the 1 st blade 346 and the 2 nd blade 348 are formed so as to be offset to the front side (the direction indicated by the arrow R) in the rotation direction of the impeller 340. Further, in a plan view of the impeller 340, the 1 st blade 346 and the 2 nd blade 348 (specifically, the upper end portions) are gradually inclined such that the radially outer end portions thereof are located on the rear side (the side opposite to the direction indicated by the arrow R) in the impeller rotation direction. In the following description, the portion having the same configuration between the 1 st blade 346 and the 2 nd blade 348 will be described while dividing the portion of the 1 st blade 346 and the portion of the 2 nd blade 348 by a slash "/".

In the 1 st blade 346 and the 2 nd blade 348, a portion formed radially inward of the main plate 344 is referred to as a 1 st inner blade portion 364 and a 2 nd inner blade portion 368, and a portion formed radially outward is referred to as a 1 st outer blade portion 366 and a 2 nd outer blade portion 370. In a plan view of the impeller 340, a connecting portion between the 1 st/2 nd

inner blade portions

364, 368 and the 1 st/2 nd

outer blade portions

366, 370 is disposed on a normal line N1/N2 which is a straight line passing through the rotation center C of the impeller 340 and extending in the radial direction of the main plate 344.

The 1 st inner blade portion 364 and the 2 nd inner blade portion 368 are disposed on the front side in the impeller rotation direction with respect to the normal line N1 and the normal line N2. The connecting portion between the 1 st/2 nd inner blade 364/368 and the 1 st/2 nd outer blade 366/370 corresponds to the end portion of the 1 st/2 nd outer blade 366/370 radially inward of the main plate 344. The front surface of the 1 st blade 346 and the 2 nd blade 348 in the impeller rotation direction is referred to as a front side surface, and the rear surface thereof in the rotation direction is referred to as a rear side surface.

Front side surface 364F/front side surface 368F and rear side surface 364R/rear side surface 368R of 1 st inner blade portion 364/2 nd inner blade portion 368 form an angle of approximately 90 degrees with the upper surface of main plate 344. About 90 degrees means, for example, 85 to 95 degrees, preferably 90 degrees.

The

front side surfaces

366F and 370F of the 1 st and 2 nd

outer blade portions

366 and 370 are formed as inclined surfaces that protrude forward in the impeller rotation direction as the height from the main plate 344 decreases. The front side surface 366F/front side surface 370F is formed continuously with the front side surface 364F/front side surface 368F of the 1 st inner blade section 364/2 nd inner blade section 368. In embodiment 3, the inclined surface extends linearly from the upper end to the lower end of the front side surface 366F/the front side surface 370F in a cross section perpendicular to the longitudinal direction of the 1 st outer blade 366/the 2 nd outer blade 370, but may be formed in a gentle convex arc shape or a gentle concave arc shape.

The inclination angles θ (in fig. 13 and 14, the 1 st outer blade 366 is shown) of the front side faces 366F and 370F of the 1 st outer blade 366 and the 2 nd outer blade 370 gradually increase from the inner side to the outer side in the impeller radial direction. The inclination angle θ is an angle of the front side surface 366F/the front side surface 370F with respect to a straight line L that is orthogonal to the surface of the main plate 344 and passes through the upper end portions of the front side surface 366F/the front side surface 370F.

In a plan view of the impeller 340 shown in fig. 12, with respect to the normal line N1/the normal line N2, the lower half portions of the front side surfaces 366F/the front side surfaces 370F of at least the radially outer ends of the 1 st outer blade portion 366/the 2 nd outer blade portion 370 are disposed on the impeller rotation direction front side, and the upper half portions of the front side surfaces 366F/the front side surfaces 370F are disposed on the impeller rotation direction rear side (see fig. 13 and 14). The end surfaces of the 1 st outer blade 366 and the 2 nd outer blade 370 on the outer side in the impeller radial direction are flush with the outer peripheral surface of the main plate 344.

As shown in fig. 13 and 14, the longitudinal thickness T of the 1 st/2 nd

outer blade portions

366, 370 gradually increases from the upper end portion to the lower end portion in the 1 st/2 nd

outer blade portions

366, 370. The rear side surfaces 366R/370R of the 1 st/2 nd outer blade portions 366/370 are formed orthogonal to the upper surface of the main plate 344. The rear side surface 366R/rear side surface 370R is formed continuously with the rear side surface 364R/rear side surface 368R of the 1 st inner blade section 364/2 nd inner blade section 368 (see fig. 11). The thickness of the 1 st inner blade section 364 and the 2 nd inner blade section 368 in the front-rear direction is constant over a range from the upper end to the lower end.

As shown by comparison in fig. 15 and 16, the 2 nd blade 348 has a low blade portion 356 and a high blade portion 358. The low blade portion 356 is located radially inward of the main plate 344, and is formed to have a height from the main plate 344 lower than that of the 2 nd blade 346 when comparing portions having equal distances from the center of the main plate 344 with each other. The high blade portion 358 is located radially outward of the low blade portion 356, and when comparing portions having equal distances from the center of the main plate 344 with each other, the height from the main plate 344 is formed to be the same as the height from the main plate 344 of the 1 st blade 346. The low vane portion 356 is located only at the protruding portion 352 of the main plate 344, and the high vane portion 358 is formed astride the protruding portion 352 and the flat plate portion 350 of the main plate 344. That is, the boundary portion (the vicinity of the boundary line B shown in fig. 15) between the low blade portion 356 and the high blade portion 358 is located at the protruding portion 352. In embodiment 3, the height of the low blade portion 356 gradually increases toward the boundary with the high blade portion 358.

(advantages of embodiment 3)

In the impeller 340 of the 3 rd embodiment, the 1 st vane 346 and the 2 nd vane 348 have the same radial length. The 2 nd blade 348 also includes: a low blade portion 356 located radially inward, and formed to be lower in height from the main plate 344 than the 2 nd blade 346 in height from the main plate 344 when comparing portions that are equidistant from the center of the main plate 344 with each other; and a high blade portion 358 which is located radially outward and is formed to have the same height from the main plate 344 as the 1 st blade 346 from the main plate 344 when comparing portions which are equally distant from the center of the main plate 344 with each other. With such a configuration, the impeller 340 can suppress the amount of fluid pressurized and fed by the 1 st vane 346 and the 2 nd vane 348 from becoming uneven while ensuring a large inlet area. Further, the pump efficiency of the centrifugal pump can be improved.

The height of the low blade portion 356 of the 2 nd blade 348 from the main plate 344 gradually increases from the radially inner side to the radially outer side. Therefore, the impeller 340 can be easily molded.

The low blade portions 356 are formed only in the protruding portions 352, and the high blade portions 358 are disposed on the flat plate portion 350. Therefore, the fluid flowing through the flat plate portion 350 can be sufficiently pressurized.

The 1 st blade 346 and the 2 nd blade 348 are alternately arranged. Therefore, the inlet area of the impeller 340 can be uniformly secured in the circumferential direction, and the amount of the fluid that is pressurized and fed by each of the 1 st vane 346 and the 2 nd vane 348 can be suppressed from becoming uneven.

[ other embodiments ]

The centrifugal pump disclosed in the present specification is not limited to the above-described embodiment, and various modifications can be made. For example, the centrifugal pump 10 may be applied to a pump used for pressurizing and conveying a gas such as air or a fluid such as a liquid other than a purge gas. In addition, a brush motor may be used as the motor instead of the brushless motor. The upper surface of the flat plate part is flat. Other blades or the like can be provided on the lower surface of the main plate as appropriate, and grooves or the like can be formed. The main plate may be formed of only the flat plate portion without the protruding portion.

In the case where the heights of the low blade portions are compared with each other at portions that are equidistant from the center of the main plate, the low blade portions may include portions that increase in height toward the radially inner side as long as the heights are lower than the height of the 1 st blade.

In embodiment 2, the thickness of the thin blade portion 260 of the 2 nd blade 248 is uniform over the entire length in the radial direction, but may be formed so as to gradually increase toward the radial outer side. Instead of the 1 st blade 246 having the thin blade portion 260 and the thick blade portion 262, the second blade 248 may have the thin blade portion 260 and the thick blade portion 262.

In embodiments 1 to 3, the impeller has the 1 st blade and the 2 nd blade, but may further have the 3 rd blade. In this case, the 3 rd blade has a low blade portion and a high blade portion as in the 2 nd blade, but the shape of the low blade portion is different from that of the 2 nd blade. For example, in the case of comparing portions having equal distances from the center of the main plate with each other, the low blade portion of the 3 rd blade is formed to have a height lower or higher than that of the 2 nd blade. The impeller may not have the same number of the 1 st blade, the 2 nd blade, and the 3 rd blade when present. However, it is preferably arranged according to a predetermined rule. For example, the 1 st blade, the 2 nd blade, and the 3 rd blade may be arranged on the main plate as a repeating unit.

The 1 st blade, the 2 nd blade, and the 3 rd blade in the case of existence may not necessarily be arranged at equal intervals. However, it is preferable to have a prescribed rule. For example, when the 1 st blade, the 2 nd blade, and the 3 rd blade are arranged as a repeating unit, the interval between the 1 st blade and the 2 nd blade, the interval between the 2 nd blade and the 3 rd blade, and the interval between the 3 rd blade and the 1 st blade may be independently set.

Claims

1. A centrifugal pump, wherein,

the centrifugal pump has:

a housing having a discharge passage and a suction passage formed therein; and

an impeller disposed in the housing so as to be coaxial with the suction passage,

the impeller has:

a base portion of a disc shape;

a 1 st vane extending outward from a radially inner side of the base portion on a front surface of the base portion, the front surface being a surface facing the suction passage; and

a 2 nd blade also on the front face, extending from the radially inner side of the base portion to an outer side,

the 2 nd blade has the same length as that of the 1 st blade in the radial direction, and has:

a low blade portion located radially inward, and formed to have a height from the base portion lower than that of the 1 st blade when comparing portions having equal distances from the center of the base portion with each other; and a high blade portion located at an outer side in the radial direction, and also formed to have a height from the base portion equal to that of the 1 st blade when comparing portions having equal distances from the center of the base portion with each other.

2. The centrifugal pump of claim 1,

the height of the low blade portion from the base portion gradually increases from the radially inner side toward the radially outer side.

3. The centrifugal pump of claim 1,

the height of the 2 nd blade from the base portion increases stepwise at a boundary portion between the low blade portion and the high blade portion.

4. A centrifugal pump according to any one of claims 1 to 3,

the centrifugal pump has:

a flat plate portion formed on the radially outer side of the base portion and flat; and a protrusion having an inclined surface which is formed continuously from an inner end of the flat plate portion toward the radial direction inner side and which is increased in height toward the radial direction inner side,

the low blade portion is formed only in the protruding portion.

5. The centrifugal pump of claim 4,

one of the 1 st blade and the 2 nd blade has:

a thin blade portion located on the radially inner side, formed to have a thickness thinner than that of the other of the 1 st blade and the 2 nd blade when comparing portions that are equidistant from the center of the base portion with each other; and a thick blade portion located radially outward of the base portion, and also formed to have the same thickness as that of the other when comparing portions that are equidistant from the center of the base portion with each other.

6. The centrifugal pump of claim 5,

the thin blade portion is formed only in the protruding portion.

7. A centrifugal pump according to any one of claims 1 to 6,

the 1 st blade and the 2 nd blade are regularly arranged.

8. The centrifugal pump of claim 7,

the 1 st blade and the 2 nd blade are alternately arranged.