JP5568383B2 - Water pump - Google Patents

Description

The present invention belongs to a technical field relating to a water pump having a b Npera.

  Conventionally, a centrifugal water pump that sucks fluid from a suction port and pressurizes and sucks the sucked fluid by a centrifugal force of an impeller is known (for example, see Patent Document 1).

  In this configuration, the impeller is disposed between a hub plate that is rotationally driven by a motor, an annular shroud (enclosure plate) that is disposed to face the hub plate, and the hub plate and the shroud. And a plurality of blades arranged at a predetermined interval in the circumferential direction.

  The impeller is accommodated in an impeller chamber provided in the pump casing. In the casing, an inflow passage communicating with the suction port in the center of the shroud and an outflow passage communicating with the impeller chamber are formed.

  A cylindrical suction portion having a suction port is formed at the center portion of the shroud, and an annular flange portion is formed at the upper end portion of the cylindrical suction portion so as to surround the outer periphery thereof. A slight gap is provided between the annular flange portion and the casing, and the inflow channel and the impeller chamber communicate with each other via the gap.

  A plurality of concave grooves are formed on the upper surface of the annular flange portion. The flow that has flowed into the gap from the impeller chamber deviates radially outwardly by receiving centrifugal force from the concave grooves. This prevents high-pressure fluid pressurized by the impeller and flowing into the impeller chamber during pump operation from leaking from the gap to the inflow channel.

Japanese Patent Laid-Open No. 9-14194

  However, in the conventional water pump, the centrifugal force is applied to the fluid by a slight concave groove formed in the annular flange portion. Therefore, when the pressure in the impeller chamber exceeds a predetermined pressure, or the pump rotational speed is low. Therefore, when sufficient centrifugal force cannot be ensured, the flow flowing into the gap from the impeller chamber cannot be deviated outward in the radial direction, and sufficient fluid leakage from the impeller chamber to the inflow channel can be achieved. There is a problem that it cannot be suppressed.

  In addition, in order to provide the above-described annular flange portion, it is necessary to ensure a sufficient height of the fluid guide portion provided in the center portion of the shroud. As a result, the impeller is increased in size and space efficiency is reduced. There's a problem.

The present invention has been made in view of the foregoing, it is an object of providing a window Otaponpu excellent in reliably suppressed possible and space efficiency leakage of fluid into the inflow channel from the impeller chamber There is to try.

    In order to achieve the above object, according to the present invention, a plurality of auxiliary blades are formed on the surface of the shroud opposite to the connection surface with the main blades, and each auxiliary blade is viewed from the central axis direction of the shroud. It was arranged at the same circumferential position as each main blade.

Specifically, in the invention of claim 1, a water pump comprising a casing having a housing space therein, and an impeller that pressurizes and discharges the fluid that is housed in the housing space and is sucked in by a rotating operation by centrifugal force. Is targeted.

The impeller includes a hub plate that is driven to rotate around a central axis, a shroud that is disposed so as to face the hub plate in the central axis direction, and has a suction port for sucking fluid into the central portion, A plurality of main blades connected to the hub plate and the shroud and arranged around the central axis at a predetermined interval; a surface of the shroud opposite to a surface to which the main blades are connected; and A plurality of auxiliary blades formed at positions around the same central axis as the plurality of main blades when viewed from the central axis direction, and an inflow passage communicating with the inlet of the impeller in the casing; A clearance channel formed between the inner peripheral surface of the casing and the shroud in the accommodating space and communicating with the inflow channel, and a communicating portion of the clearance channel with the inflow channel is the above The suction port periphery of the shroud approaches the shroud side opening periphery of the inflow channel so that the inner peripheral surface of the casing forming the inlet flow channel and the inner peripheral surface of the shroud forming the suction port are flush with each other. The flow passage cross-sectional area is smaller than the flow passage cross-sectional area between the casing and the surface on which the auxiliary blades are formed in the shroud, and the auxiliary blades It is assumed that it extends from the vicinity of the fluid leakage regulating portion to the outer peripheral edge of the shroud .

According to this structure, when used as a pump incorporating the impeller casing, the high pressure of the fluid after passing through the impeller, it is attracted to the negative pressure of the inlet passage which communicates with the inlet impeller Leakage into the inflow channel from the gap between the shroud and the casing can be prevented.

  That is, in the present invention, the auxiliary blade is provided on the surface of the shroud opposite to the connection surface with the main blade (hereinafter referred to as the back surface of the shroud), so that the high-pressure fluid that has passed through the impeller flows into the inflow flow. Even if it is attracted by the negative pressure of the road and wraps around the back surface of the shroud, the fluid can be actively discharged radially outward by the auxiliary blade. Thereby, it is possible to prevent the fluid from leaking from the gap to the inflow channel.

  Further, in the present invention, the pressure difference between both surfaces of the shroud (the connection surface with the main blade in the shroud and the back surface on the opposite side) is applied by pressurizing the fluid flowing around the back surface of the shroud by the auxiliary blade. Can be reduced. Thereby, the flow of the fluid which goes around to the back surface of a shroud after passing an impeller can be suppressed. Therefore, the leakage of the fluid to the inflow channel can be reliably suppressed. In particular, in the present invention, the auxiliary blades are arranged at the same circumferential position as the main blades when viewed from the central axis direction, so that the pressure pulsation caused by the passage of the auxiliary blades on the back surface of the shroud. And the pressure pulsation that accompanies the passage of the main blade at the connecting surface of the shroud with the main blade can be synchronized. As a result, the pressure difference between the two surfaces of the shroud can be reduced as much as possible, and the flow that wraps around the back surface of the shroud described above can be reliably suppressed. As a result, fluid leaks into the inflow channel. Can be prevented.

Moreover, according to the structure of Claim 1, the pump efficiency falls by cooling water (fluid) leaking into an inflow channel by applying the above-mentioned impeller to the water pump used for engine cooling, for example. Can be prevented.

Furthermore, according to the configuration of claim 1, in a water pump (for example, a water pump for engine cooling) in which the operating speed of the pump covers a wide range, the cooling water ( Leakage of the fluid into the inflow channel can be reliably prevented. That is, when the pump speed is low, the centrifugal force acting on the fluid is smaller than that of the auxiliary blade. For this reason, the fluid flow that flows around the back surface of the shroud cannot be sufficiently eliminated by the auxiliary blades, and the cooling water easily leaks from the gap channel to the inlet channel. On the other hand, in the present invention, a fluid leakage restricting portion having a channel cross-sectional area smaller than the channel cross-sectional area between the casing and the back surface of the shroud is formed at the end of the gap channel on the inflow channel side. By doing so, the fluid leakage restricting portion becomes a fluid resistance, and leakage of the fluid into the inflow channel can be suppressed. Therefore, leakage of cooling water can be reliably suppressed even in an operation region where the pump rotational speed is relatively low, and the operating efficiency of the pump can be maintained at a high value regardless of the pump rotational speed.

  According to a second aspect of the present invention, in the first aspect of the invention, the auxiliary blade is formed so as to have the same shape as the main blade at the same circumferential position as the main blade when viewed from the central axis direction. Shall.

  According to this configuration, the waveform of the pressure pulsation generated on the back surface of the shroud can be made as close as possible to the waveform of the pressure pulsation generated on the connection surface on the opposite side. Therefore, the pressure difference between both surfaces of the shroud can be further reliably reduced.

  In the invention of claim 3, in the invention of claim 1 or 2, the height of the auxiliary blade is approximately 1/10 or less of the height of the main blade.

According to this configuration, even stirring resistance of the fluid is increased at the time of pump operation moving the provision of the support blade, the operating efficiency of the pump can be improved as a whole. That is, the inventors have intensively studied, and if the height of the auxiliary blade is about 1/10 or less of the height of the main blade, the effect of improving the pump efficiency by preventing the fluid from flowing into the inflow channel is It has been found that the pump efficiency is reduced by an increase in resistance, and the configuration of the present invention has been conceived. In the present specification, the “blade height” means the length of the vane in the central axis direction .

As described above, according to the present invention, a plurality of auxiliary blades are formed on the surface of the shroud opposite to the connecting surface with the main blades, and each auxiliary blade is viewed from the central axis direction of the shroud. by the so disposed in the same circumferential position as the blades, while achieving downsizing of the impeller may be a high-pressure fluid passing through the i Npera can be inhibited from leaking into the inflow channel.

It is a figure which shows the internal structure of the water pump provided with the impeller which concerns on Embodiment 1 of this invention. It is the perspective view which looked at the impeller from the suction side (one side) and radial direction outer side of a pump shaft center direction. FIG. 3 is a view in the direction of arrow III in FIG. 2. It is the top view which looked at the impeller from the suction side (one side) of a pump shaft center direction. It is the VV sectional view taken on the line of FIG. It is explanatory drawing for demonstrating the effect of an auxiliary | assistant blade | wing, Comprising: It is the graph which showed typically the pressure fluctuation in the impeller chamber accompanying rotation of an impeller. FIG. 3 is a view corresponding to FIG. FIG. 3 is a view corresponding to FIG. FIG. 6 is a view corresponding to FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 shows a water pump 1 according to Embodiment 1 of the present invention, which is attached to a water-cooled engine and forcibly circulates cooling water through the engine.

The water pump 1 is a so-called centrifugal pump comprises a casing 3 having an impeller chamber 18 (accommodating space) therein is housed in the impeller chamber 18, is sucked by the rotational operation cooling water (fluid) And an impeller 2 that is pressurized and discharged by centrifugal force .

The casing 3 includes a first casing 5 having an inflow channel 4 into which cooling water flows, and a second casing 8 having a shaft support hole 7 for supporting a drive shaft 6 that drives the impeller 2 (hub plate 22). The casings 5 and 8 are fastened to each other via bolts 9. In the following description, the suction side (right side in FIG. 1) in the direction of the pump axis is defined as “one side”, and the opposite side (left side in FIG. 1) is defined as “other side”.

  The inflow channel 4 is formed in a tapered shape whose diameter increases from one side to the other side. A pipe connection hole 15 is formed at one end of the inflow channel 4, and an inflow pipe 16 for guiding cooling water from the engine into the pump 1 is connected to the connection hole 15. .

  A spiral impeller chamber 18 (vortex chamber) is formed on the mating surface portion 17 of the first and second casings 8 so as to surround the outer periphery of the impeller 2. The impeller chamber 18 has a discharge port (not shown) for discharging the cooling water pressurized by the impeller 2 to the engine side, and an outflow passage is in communication with the discharge port. A sealing groove 11 into which an O-ring 10 is fitted is formed on the mating surface of the second casing 8 with the first casing 8 in order to ensure the sealing property of the impeller chamber 18.

  The impeller 2 is connected to a crankshaft of an engine via a drive shaft 6 so that power can be transmitted. The drive shaft 6 is rotatably supported by a bearing 20 press-fitted into the shaft support hole 7. A mechanical seal 19 is attached to an intermediate position between the bearing 20 and the impeller chamber 18 in the drive shaft 6, thereby preventing the coolant from leaking into the shaft support hole 7. A pump pulley 21 around which a drive belt (not shown) is wound is attached to the other end of the drive shaft 6. The driving belt is wound around a crank pulley (not shown) attached to the crankshaft of the engine and the pump pulley 21.

Said impeller 2, made up of a resin molded article, as shown in FIG. 2, a hub plate 22 that is driven to rotate Ri peripheral pump axis, to the hub plate 22 in the pump axial direction is disposed so as to face, the shroud 24 having a suction port for sucking the cooling water in the center, is connected to the hub plate 22 and the shroud 24, a plurality arranged at equal intervals in Ri peripheral pump axis ( In this embodiment, seven main blades 25 are provided. An auxiliary blade 26 is formed on one side surface 43 of the shroud 24 in the central axis direction (coincident with the pump axis direction), as will be described in detail later.

  The hub plate 22 is formed in a disc shape, and a boss portion 28 having a fastening hole 27 into which the drive shaft 6 is inserted is formed at the center thereof.

The shroud 24 includes a cylindrical suction portion 29 having a suction port communicating with the inflow passage 4 and a slightly outward side from the other end of the cylindrical suction portion 29 in the pump axis direction toward the radially outer side. It is comprised with the shroud main body 30 which inclines (refer FIG.1 and FIG.2).

  The main blade 25 has a predetermined airfoil shape that bulges to the front side in the rotational direction of the impeller 2 when viewed from the pump axial direction (see FIG. 4). The height of the main blade 25 gradually increases from the outer edge of the shroud 24 toward the inside in the radial direction, and reaches the maximum height H at the inner edge of the shroud 24 (see FIG. 5).

  As shown in FIG. 3, the corner portion 41 a to which the positive pressure surface 36 on the front side in the rotation direction of the main blade 25 and the shroud 24 (the shroud body 30) are connected, and the positive pressure surface 36 and the hub plate 22 are connected. The corner portion 41b is formed at a substantially right angle when viewed from the radial direction. As a result, a sufficient discharge volume of the cooling water can be secured on the pressure surface 36 side where the cooling water (fluid) is unlikely to peel off.

An auxiliary blade 26 is formed on a surface 43 (one side surface 43 in the pump axial direction) opposite to the connection surface (other side surface) 40 with the main blade 25 in the shroud body 30. Auxiliary vanes 26, the main blade 25 and be provided seven similarly, are formed at equal intervals in the pump axial circumferential Rinishu direction.

  As shown in FIG. 4, the auxiliary blade 26 is formed in the same shape at the same circumferential position as the main blade 25 (the phase position around the central axis is the same) when viewed from the pump axis direction. That is, the main blade 25 is formed along the main blade 25 so as to overlap the main blade 25 when viewed from the pump axial direction.

As shown in FIG. 5, the height of the auxiliary blade 26 gradually increases from the outer peripheral side to the center side of the shroud 24, and reaches substantially the same height h as the cylindrical suction portion 29 at the inner peripheral edge of the shroud 24. It has become. That is, the auxiliary blade 26 extends from the vicinity of a fluid leakage regulating portion 39 described later to the outer peripheral edge of the shroud 24. The maximum height h of the auxiliary blades 26 is 1/10 or less (1/15 in this embodiment) of the maximum height H of the main blades 25.

  A dish-shaped recess 5 a that is recessed in a dish shape so as to receive the shroud 24 is formed at the other end of the inflow channel 4 in the first casing 5 (see FIG. 1).

Between the wall (casing 3 inner peripheral surface) and a shroud 24 which forms a dish-like recess 5a of the first casing 5 is formed with a small gap, the gap passage is formed by the gap between this 38 Is in communication with the inflow channel 4 . At the end of the clearance channel 38 on the side of the inflow channel 4, the channel cross-sectional area is between one side 43 of the shroud body 30 and the first casing 5 (the peripheral wall of the dish-shaped recess 5 a in the first casing). A fluid leakage restricting portion 39 smaller than the flow path cross-sectional area is formed.

The fluid leakage restricting part 39 has a sufficiently small distance d between one end face of the cylindrical suction part 29 and the bottom wall surface of the dish-like recess 5a of the first casing 5 (for example, one side 43 of the shroud body 30 and the dish 1/10 or less of the distance D from the peripheral wall surface of the concave portion 5a). In other words, a portion of the gap channel 38 that communicates with the inflow channel 4 constitutes the fluid leakage restriction part 39, and the fluid leakage restriction part 39 has an inner periphery of the casing 3 that forms the inflow channel 4. The periphery of the suction port in the shroud 24 approaches the opening periphery on the shroud 24 side in the inflow channel 4 so that the surface and the inner peripheral surface of the cylindrical suction portion 29 having the suction port are flush with each other.

  In FIG. 1, the distance d is drawn larger than the actual distance for easy understanding.

And configured the water pump 1 is operated as described above, when the impeller 2 is rotated by a driving shaft 6, cooling water from the engine through the suction port of the inlet passage 4 and a cylindrical suction portion 29 the impeller The cooling water that has flowed into the pressure chamber 2 is pressurized by the main blades 25 of the impeller 2 and flows into the impeller chamber 18 by its centrifugal action. The cooling water flowing into the impeller chamber 18 is discharged from a discharge port (not shown) and supplied to each part of the engine.

  Here, since the negative pressure is generated in the inflow channel 4 in a state where the pump 1 is operating, in the conventional pump, the pressurized cooling water that has flowed into the impeller chamber 18 is transferred to the gap channel. There is a problem that the pump efficiency is lowered due to leakage into the inflow passage 4 through the passage 38.

  On the other hand, in the above embodiment, the auxiliary blades 26 arranged at equal intervals in the circumferential direction are formed on the one side surface 43 of the shroud body 30 as described above, so that the negative pressure of the inflow channel 4 is drawn. The flow (arrow flow indicated by a two-dot chain line in the figure) that is circulated on the one side surface 43 is actively discharged radially outward by the auxiliary blades 26, so that one side and the other side of the shroud main body 30 are discharged. Can be reduced as much as possible. As a result, the cooling water flowing into the impeller chamber 18 is prevented from flowing into one side surface of the shroud body 30 due to the negative pressure of the inflow channel 4 and leaking into the inflow channel 4 from the gap channel 38. can do.

  Further, by discharging (excluding) the cooling water to the outside in the radial direction by the auxiliary blades 26, the pressure difference between the both surfaces 40, 43 of the shroud main body 30 can be reduced and the flow around the one side surface 43 can be suppressed. . That is, as schematically shown in FIG. 6, the pressure on the other side surface 40 of the shroud body 30 (pressure indicated by the solid line in FIG. 6) periodically fluctuates (pulsates) as the main blade 25 passes. When the auxiliary blade 26 is not provided, the pressure on the one side surface 43 of the shroud main body 30 is affected by the negative pressure of the inflow channel 4, and as shown by the one-dot chain line in FIG. Although the value is considerably lower than the pressure of 40, as described above, by providing the auxiliary blade 26, as shown by the two-dot chain line in FIG. Thus, the pressure difference between the one side surface 43 and the other side surface 40 of the shroud body 30 can be reduced. Therefore, the flow which goes around from the other side of the shroud main body 30 to the one side can be reliably suppressed, and further, the leakage of the cooling water to the inflow channel 4 can be suppressed.

  Further, in the above embodiment, the auxiliary blade 26 is formed at the same circumferential position as the main blade 25 when viewed from the pump axial direction, so that each of the pressure fluctuations generated on the other side of the shroud main body 30 is determined. The phase position of the peak and each peak of pressure fluctuation generated on one side of the shroud main body 30 can be substantially matched. Therefore, as compared with the case where the circumferential position of the auxiliary blade 26 is different from the circumferential position of the main blade 25, the maximum value Pd of the pressure difference between the both surfaces 40, 43 of the shroud body 30 (the pressure peak value of the one side surface 43). And the pressure peak value of the other side surface 40) can be reduced, and the cooling water can be more reliably suppressed from flowing to one side of the shroud body 30 due to the pressure difference Pd. As a result, it is possible to prevent leakage of the cooling water into the inflow channel 4.

  Further, in the above-described embodiment, the auxiliary blade 26 is formed along the main blade 25 (in the same shape as the main blade 25) so as to overlap with the main blade 25 when viewed from the pump axial direction. Thus, the shape (height or the like) of each peak of pressure fluctuation generated on one side of the shroud main body 30 can be made closer to the shape of each peak of pressure fluctuation generated on the other side of the shroud main body 30. Therefore, the pressure difference Pd can be further reduced.

  Here, if the height h of the auxiliary blade 26 is too high, the stirring resistance of the cooling water by the auxiliary blade 26 is increased, which may reduce the pump efficiency. On the other hand, the inventors have intensively studied and, if the ratio of the maximum height h of the auxiliary blades 26 to the maximum height H of the main blades 25 is approximately 1/10 or less, the cooling water inflow channel 4. It has been found that the effect of improving the pump efficiency by preventing leakage into the water exceeds the decrease in pump efficiency due to the increase in the stirring resistance, and in the above embodiment, this ratio is set to 1/15 that is 1/10 or less. .

  By the way, in the said embodiment, the water pump 1 is connected with the crankshaft of an engine so that power transmission is possible, and operate | moves in a comparatively wide rotation speed area | region (for example, 500 rpm-8000 rpm) according to the rotation speed change of an engine. Is required. However, in an operation region where the pump speed is low (for example, a region of 500 to 1000 rpm), the centrifugal force acting on the cooling water from the auxiliary blades 26 is reduced. 26, the possibility that the cooling water leaks into the inflow channel 4 through the gap channel 38 is increased.

  On the other hand, in the above-described embodiment, the end surface of the fluid leakage channel 38 on the side of the inflow channel 4 has a channel cross-sectional area between the shroud body 30 and the casing 3 (first casing 5). By providing the fluid leakage restricting portion 39 that is sufficiently smaller than the cross-sectional area, the fluid leakage restricting portion 39 becomes a fluid resistance, and leakage of cooling water can be suppressed. Therefore, leakage of cooling water can be reliably suppressed even in an operation region where the pump speed is low, and high pump efficiency can be realized regardless of the speed.

  Moreover, in the said embodiment, the height of the auxiliary blade | wing 24 is the lowest in the outer edge part of the shroud 24. FIG. As a result, the distance between the outer edge of the shroud 24 and the casing 5 can be made smaller than when the height of the auxiliary blades 26 is constant. Therefore, the cross-sectional area of the end of the gap channel 38 on the impeller chamber 18 side can be made sufficiently small, and the inflow of cooling water into the gap channel 38 can be further reliably suppressed.

(Embodiment 2)
7 to 9 show the second embodiment of the present invention, in which the shape of the auxiliary blade 26 is different from that of the first embodiment. In FIG. 7, unlike FIG. 1, the impeller 2 is also shown as a cross section. 7 to 9, components substantially the same as those in FIGS. 1, 2, and 5 are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

  That is, in the present embodiment, the auxiliary blades 26 are formed in the same shape at the same circumferential position as the main blades 25 when viewed from the pump axial direction as in the first embodiment. The height is kept constant without increasing from the outer peripheral side of the shroud 24 toward the center side. Thereby, the centrifugal force which acts on cooling water from the auxiliary blade 26 can be increased as much as possible.

(Other embodiments)
The configuration of the present invention is not limited to the above embodiments, but includes various other configurations. In other words, required by the above SL embodiments, the auxiliary blade 26, when viewed from the pump axis direction is formed in the same shape as the main blade 25, but not necessarily the same shape as long as the same position about the central axis There is no.

In the above embodiments, the water pump 1 has been a pump for engine cooling operating in a relatively wide speed range, for example, operating speed may be a pump which is fixed.

  Further, in the first embodiment, the inflow channel 4 is formed in a tapered shape whose diameter increases from one side to the other side, but is not limited to this, and is formed in a straight shape with a constant inner diameter. You may make it do (refer FIG. 7 of Embodiment 2).

The present invention is especially useful for the water pump for engine cooling.

H Height of main blade h Height of auxiliary blade 1 Water pump 2 Impeller 4 Inflow passage 18 Impeller chamber 22 Hub plate
2 4 shroud
25 Main feather
26 Auxiliary blade 38 Gap channel 39 Fluid leakage restricting portion 40 Other side surface (surface on the side of the shroud to which the main blade is connected)
43 One side surface (surface on the opposite side to the surface on which the main blades are connected in the shroud)

Claims (3)

A casing having an accommodating space inside,
A water pump including an impeller that is accommodated in the accommodation space and that pressurizes and discharges the fluid sucked in by a rotating operation by centrifugal force,
The impeller includes a hub plate that is driven to rotate about a central axis, a shroud that is disposed so as to face the hub plate in the direction of the central axis, and that has a suction port for sucking fluid into the center, and the hub is connected to the plate and the shroud, said plurality of main wings to Ri central axis circumferential aligned at a Tokoro interval constant, at the surface opposite to the side on which the main blade is connected in the shroud, and , and a plurality of auxiliary blades formed on positions around the same central axis as the upper Symbol plurality of main blade as viewed from the central axis direction,
In the casing, there are an inflow channel communicating with the inlet of the impeller, and a gap channel formed between the inner peripheral surface of the casing and the shroud in the housing space and communicating with the inflow channel. Provided,
The communicating portion of the gap channel with the inflow channel is a suction in the shroud so that the inner peripheral surface of the casing forming the inflow channel and the inner peripheral surface of the shroud forming the suction port are flush with each other. The periphery of the mouth is formed by approaching the opening periphery on the shroud side in the inflow channel, and the cross-sectional area of the channel is the cross-sectional area of the channel between the casing and the surface on which the auxiliary blades are formed in the shroud. A smaller fluid leakage regulating part,
The water pump according to claim 1, wherein the auxiliary blade extends from the vicinity of the fluid leakage restricting portion to an outer peripheral edge of the shroud . The water pump according to claim 1,
The water pump , wherein the auxiliary blade is formed to have the same shape as the main blade at the same circumferential position as the main blade when viewed from the central axis direction. The water pump according to claim 1 or 2,
The height of the auxiliary blade, water pump, characterized in that is less than approximately one-tenth of the height of the main blade.

Images