Water pump

Abstract

The invention provides a water pump with excellent efficiency without using a high-precision mold. A water pump (100) according to the present invention is provided with: a housing (120) having a fluid inflow part (123) and a fluid outflow part (125); and an impeller (140) rotatably supported on the inside of the housing (120), the impeller (140) having a base (142) and a plurality of blades (145) provided on the base (142), the blades (145) having a negative pressure side surface (145a) and a pressure side surface (145b) with respect to the fluid, and having an inclined surface (146) at the inner peripheral end of the negative pressure side surface (145a), the base (142) has an inclined surface (146) formed so as to be inclined at a prescribed angle along the inflow angle of the fluid flowing in from the inflow part, and has a through-hole (143h) adjacent to the inclined surface (146) in the direction in which the blade (145) extends.

Description

Technical Field

[0001] The present invention relates to a water pump. Background Art

[0002] In recent years, a water pump has been proposed that reduces the collision loss and wake between the cooling water and the inlet-side end of the blades by thinning the blades at the inlet-side end and the outlet-side end when cooling water flows in, thereby improving pump efficiency (for example, see Patent Document 1).

[0003] In the water pump of Patent Document 1, impeller 1 has multiple blades 3 formed in an arc shape that curves from the radial direction to the circumferential direction of shaft 13 . The rotation of impeller 1 causes cooling water to flow along blades 3 and be discharged from cooling water outlet 12 .

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-67617 Summary of the Invention

[0008] Problems to be solved by the invention

[0009] As described above, in the water pump of Conventional Document 1, the tip of the blade 3 has a suction surface inlet portion 8c extending along the inlet circle 4, and the blade 3 thickness decreases toward the inlet-side end. Therefore, while the water pump of Conventional Document 1 reduces collision loss generated when cooling water is drawn in, improving pump efficiency, further improvements in pump efficiency are desired.

[0010] In view of the above situation, one of the technical problems of the present invention is to provide a water pump with a simple structure that further improves pump efficiency.

[0011] Solutions for solving problems

[0012] The water pump of the present invention comprises: a casing having an inflow portion for a fluid and an outflow portion for the fluid; and an impeller rotatably supported on the inner side of the casing, the impeller having a base and a plurality of blades arranged on the base, the blades having a negative pressure side and a pressure side relative to the fluid, an inclined surface at the end portion on the inner circumference side of the negative pressure side, the inclined surface being formed to be inclined at a prescribed angle along the inflow angle of the fluid flowing in from the inflow portion, and the base having a through hole adjacent to the inclined surface in the extending direction of the blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1It is a perspective view showing the external appearance structure of a water pump as an example embodiment of the present invention.

[0014] Figure 2 It is a longitudinal sectional view showing the structure of a water pump according to an embodiment of an example of the present invention.

[0015] Figure 3 This is a perspective view showing the external appearance structure of an impeller of a water pump as an example embodiment of the present invention, as viewed from above.

[0016] Figure 4 This is a partially enlarged view showing a water pump as an example embodiment of the present invention, in which the inclined surface formed on the inner end portion of the blade has an inclination angle of 28 degrees.

[0017] Figure 5 This is a partially enlarged view showing a water pump as an example embodiment of the present invention, in which the inclined surface formed on the inner end portion of the blade has an inclination angle of 38 degrees.

[0018] Figure 6 This is a graph showing static pressure when the inclination angle of the blades of a water pump according to an example embodiment of the present invention is 28 degrees.

[0019] Figure 7 This is a graph showing the pump efficiency when the inclination angle of the blades of a water pump according to an example embodiment of the present invention is 28 degrees.

[0020] Figure 8 This is a graph showing static pressure when the inclination angle of the blades of a water pump according to an example embodiment of the present invention is 38 degrees.

[0021] Figure 9 This is a graph showing the pump efficiency when the inclination angle of the blades of a water pump according to an example embodiment of the present invention is 38 degrees.

[0022] Figure 10 This is a plan view showing the structure (1) of an impeller of a water pump according to another embodiment of an example of the present invention.

[0023] Figure 11 This is a plan view showing the structure (2) of an impeller of a water pump according to another embodiment of the present invention.

[0024] Figure 12 This is a partially enlarged view showing the structure (2) of an impeller of a water pump according to another embodiment of the present invention. DETAILED DESCRIPTION

[0025] <Implementation Method>

[0026] Hereinafter, an embodiment as an example of the present invention will be described with reference to the drawings. Figure 1 It is a perspective view showing the external appearance structure of a water pump as an example embodiment of the present invention. Figure 2 It is a longitudinal sectional view showing the structure of a water pump according to an embodiment of an example of the present invention. Figure 3 This is a perspective view showing the external appearance structure of an impeller of a water pump as an example embodiment of the present invention, as viewed from above.

[0027] Figure 4 This is a partially enlarged view showing a water pump as an example embodiment of the present invention, in which the inclined surface formed on the inner end portion of the blade has an inclination angle of 28 degrees. Figure 5 This is a partially enlarged view showing a water pump as an example embodiment of the present invention, in which the inclined surface formed on the inner end portion of the blade has an inclination angle of 38 degrees.

[0028] Figure 6 This is a graph showing static pressure when the inclination angle of the blades of a water pump according to an example embodiment of the present invention is 28 degrees. Figure 7 This is a graph showing the pump efficiency when the inclination angle of the blades of a water pump according to an example embodiment of the present invention is 28 degrees. Figure 8 This is a graph showing static pressure when the inclination angle of the blades of a water pump according to an example embodiment of the present invention is 38 degrees. Figure 9 This is a graph showing the pump efficiency when the inclination angle of the blades of a water pump according to an example embodiment of the present invention is 38 degrees.

[0029] It should be noted that in the description of this embodiment, for convenience, the direction indicated by arrow a along axis X is referred to as the upper side or one side. The direction indicated by arrow b along axis X is referred to as the lower side or the other side. The directions indicated by arrows ab are referred to herein as the up-down direction or the X-axis direction. However, the up-down direction does not necessarily coincide with the longitudinal direction. Furthermore, the directions indicated by arrows cd are referred to as radial directions, the direction indicated by arrow c away from axis X is referred to as the outer side or one radial side, and the direction indicated by arrow d closer to axis X is referred to as the inner side or the other radial side.

[0030] <Water Pump Structure>

[0031] like Figure 1 As shown, the water pump 100 is, for example, a so-called centrifugal pump that delivers cooling water for the engine.

[0032] The water pump 100 has: three flanges 135 (at Figure 1Only two flanges 135 are shown in the figure), which are used to assemble the water pump 100 in the engine room, etc.; the upper housing 120 is roughly conical when viewed from the side, and the impeller accommodating space 180s ( Figure 2 and a cylindrical or substantially cylindrical lower housing 130, which houses a motor 170 ( Figure 2 ).

[0033] The flanges 135 of the water pump 100 are radially extending outward at 120-degree intervals on the outer circumference of the lower housing body 131 of the lower housing 130. The flanges 135 have a generally circular opening 135a at their ends. Therefore, the water pump 100 is mounted in an engine compartment, etc. (not shown), via the opening 135a of the flange 135.

[0034] <Upper housing>

[0035] The upper housing 120 of the water pump 100 is a molded product formed by injection molding of resin.

[0036] like Figure 1 and Figure 2 As shown, the upper shell 120 includes: an upper shell body 121, which is composed of a box body that internally accommodates an impeller 140 for performing the function of a pump; a cylindrical inlet portion 123 that protrudes axially upward (in the direction of arrow a) at the center of the outer peripheral surface of the upper shell body 121, and is used to allow cooling water to flow from the outside to the impeller 140; and a cylindrical outflow portion 125 that protrudes from the outer peripheral surface of the upper shell body 121 in a radial direction orthogonal to the inflow portion 123, and is used to discharge the cooling water to the outside through the rotation of the impeller 140.

[0037] The inlet 123 has a cylindrical shape extending upward in the X-axis direction (in the direction of arrow a) from the top of the upper casing body 121 and is a portion into which fluids such as water or cooling water flow. The outflow portion 125 has a cylindrical shape extending outward in a radial direction perpendicular to the inflow portion 123 (in the direction of arrow c) from the outer peripheral surface of the upper casing body 121 and is a portion through which the fluid flowing in from the inflow portion 123 is discharged (pressurized) to the outside by the rotation of the impeller 140.

[0038] The upper shell body 121 is composed of a bowl shape that is roughly conical when viewed from the side, and has an annular protrusion 121p on the bottom surface of the outer peripheral side, and has a conical or roughly conical impeller accommodating space 180s that can accommodate the impeller 140 at a position closer to the inside (in the direction of arrow d) than the protrusion 121p.

[0039] The protrusion 121 p of the upper case body 121 is a portion that is embedded in the stator holder 180 formed of a resin molded product and then thermally welded thereto, so that the upper case body 121 and the stator holder 180 are integrally formed.

[0040] The upper casing body 121 includes a shaft support portion 124 that protrudes a predetermined length from the lower portion of the inlet portion 123 toward the impeller accommodation space 180s. The shaft support portion 124 is integrally connected to the inlet portion 123 by a plurality of (e.g., three) arms 124a provided on the inner circumference of the inlet portion 123 at predetermined angles.

[0041] A substantially cylindrical shaft support portion 124p is provided at the center of the plurality of arm portions 124a. The inner circumference of the lower end portion (in the direction of arrow b) of the shaft support portion 124p supports the upper end portion (in the direction of arrow a) of a shaft 165 described later.

[0042] In this case, the end portion of the shaft 165 on the lower side in the X-axis direction (in the direction of arrow b) is fixed as a whole with the inner circular plate portion 185 of the stator retainer 180 described later, and the end portion on the upper side in the X-axis direction (in the direction of arrow a) is supported on the shaft support portion 124, thereby suppressing the oscillating rotation of the shaft 165.

[0043] The shaft support portion 124p of the shaft support portion 124 has an annular flange portion 124d that slightly extends radially outward (in the direction of arrow cd) at its outer peripheral end on the lower side (in the direction of arrow b). The flange portion 124d is a flange portion that has a fluid flowing from the inlet portion 123 toward the blades 145 ( Figure 2 ) The direction change part of the guided function.

[0044] <Lower housing>

[0045] like Figure 2 As shown, the lower shell 130 is a molded product formed by resin injection molding, and has: a lower shell body 131 with a bottom cylindrical shape; and an annular flange portion 132, extending from the end of the upper side (direction of arrow a) of the lower shell body 131 toward the radial outside (direction of arrow c).

[0046] Flange 132 of lower case 130 is positioned opposite protrusion 121p of upper case body 121, with flange 183 of stator holder 180 interposed therebetween. The outer diameter of flange 132 of lower case 130 is identical to both the outer diameter of upper case body 121 and the outer diameter of flange 183 of stator holder 180.

[0047] A stator holder 180 is integrally fixed inside the lower housing 130. Thus, the bottom plate portion 131b of the lower housing body 131 of the lower housing 130 and the inner cylindrical portion 182 of the stator holder 180 form a stator accommodation space 130s capable of accommodating the stator 160 of the motor 170.

[0048] At the joint surface between the end of the lower side (in the direction of arrow b) of the lower shell body 131 and the end of the lower side (in the direction of arrow b) of the stator retaining frame 180, a waterproof seal 189, for example composed of an O-ring, is provided to prevent water from entering from the outside and reaching the internal circuit substrate 191.

[0049] <Stator Cage>

[0050] The stator holder 180 is a molded product formed by injection molding of a resin, and includes an outer cylindrical portion 181 , an inner cylindrical portion 182 , a flange portion 183 , an outer circular plate portion 184 , and an inner circular plate portion 185 .

[0051] The outer cylindrical portion 181 of the stator holder 180 is a cylindrical portion formed integrally with the inner surface of the lower case body 131 of the lower case 130 , and has a length reaching the bottom plate portion 131 b of the lower case body 131 .

[0052] The outer cylindrical portion 181 is formed integrally with a flange portion 183 extending from its upper end (in the direction of arrow a) toward the outside (in the direction of arrow c) and an annular outer circular plate portion 184 extending from its upper end (in the direction of arrow a) toward the inside (in the direction of arrow d).

[0053] The flange portion 183 has an annular groove 183m provided at a position corresponding to the protrusion 121p of the upper case body 121. When the protrusion 121p of the upper case body 121 is fitted into the groove 183m of the flange portion 183, the two are formed integrally.

[0054] The inner cylindrical portion 182 is located inward (in the direction of arrow d) of the outer cylindrical portion 181 and is arranged parallel to the outer cylindrical portion 181 along the X-axis direction (in the direction of arrows ab). The inner cylindrical portion 182 extends a predetermined length from the inner end (in the direction of arrow d) of the outer circular plate portion 184 toward the lower side (in the direction of arrow b). The inner cylindrical portion 182 is formed so that its vertical length (in the direction of arrows ab) is shorter than that of the outer cylindrical portion 181.

[0055] The outer circular plate portion 184 is a thin, annular portion that connects the upper end (in the direction of arrow a) of the outer cylindrical portion 181 and the upper end (in the direction of arrow a) of the inner cylindrical portion 182. A stator accommodating space 130s is formed on the lower side (in the direction of arrow b) of the outer circular plate portion 184. This stator accommodating space 130s houses the stator 160. Specifically, the stator core 161 of the stator 160 is fixed to the outer circumferential surface of the inner cylindrical portion 182.

[0056] The inner circular plate portion 185 is a disc-shaped portion integrally formed with the lower end (in the direction of arrow b) of the inner cylindrical portion 182, forming the bottom of the impeller housing space 180s, described later. The inner circular plate portion 185 has a circular through-hole 185h at its center when viewed from above. The lower end (in the direction of arrow b) of the shaft 165 is press-fitted into through-hole 185h of the inner circular plate portion 185, forming an integral unit.

[0057] An impeller accommodating space 180s is formed inside the inner cylindrical portion 182 (in the direction of arrow d) and above the inner circular plate portion 185 (in the direction of arrow a). The impeller main body 141 of the impeller 140 is accommodated in the impeller accommodating space 180s.

[0058] The inner circular plate portion 185 has a protrusion 185p that slightly protrudes downward (in the direction of arrow b) around the through hole 185h. The outer diameter of the protrusion 185p is smaller than that of the inner circular plate portion 185. A thin, annular circuit board support plate 188 is fixed to the outer circumference of the protrusion 185p. The outer diameter of the circuit board support plate 188 is slightly smaller than the inner diameter of the outer cylindrical portion 181.

[0059] A circuit board 191 is disposed inside outer cylindrical portion 181 (in the direction of arrow d) and below inner circular plate portion 185 and circuit board support plate 188 (in the direction of arrow b). Various electronic components 193 constituting a motor drive control circuit for driving the motor are mounted on this circuit board 191. Circuit board 191 is integrally mounted to circuit board support plate 188 via support posts 187.

[0060] <Stator>

[0061] Stator 160 accommodated in stator accommodation space 130s includes stator core 161, insulator 162, and coil 163. Stator 160 is integrally fixed to the outer peripheral surface (in the direction of arrow c) of inner cylindrical portion 182 of stator holder 180.

[0062] That is, the stator 160 is arranged to surround the impeller body 141 of the impeller 140 and the rotor magnet 159 arranged in the impeller accommodating space 180 s.

[0063] In this stator 160, a stator core 161 having a coil 163 wound therearound via an insulator 162 is fixed integrally to the outer circumferential surface of an inner cylindrical portion 182 of a stator holder 180. That is, the stator 160 and the stator holder 180 are integrated.

[0064] Stator core 161 is formed of a laminated body formed by laminating a plurality of electromagnetic steel sheets made of a soft magnetic material, and includes an annular core back, teeth (not shown) around which coils 163 are wound, and salient poles (not shown).

[0065] <Rotor>

[0066] like Figure 2 As shown, the rotor 150 is composed of an impeller body 141 and a rotor magnet 159. Here, the impeller body 141 is also a portion that functions as a rotor, and therefore may be referred to as the rotor body 141 below.

[0067] Rotor 150 rotates about shaft 165, which is fixed to inner circular plate 185 of stator holder 180, with shaft 165 serving as the center of rotation. Shaft 165 is non-rotatably fixed within impeller housing space 180s by inner circular plate 185 of stator holder 180. Therefore, while rotor 150 rotates, shaft 165 does not rotate and remains integrally fixed to stator holder 180.

[0068] Rotor 150 is disposed in impeller accommodation space 180s of stator holder 180, and the outer diameters of rotor body 141 and rotor magnet 159 are smaller than the inner diameter of inner cylindrical portion 182. This prevents rotor body 141 and rotor magnet 159 from contacting the inner circumferential surface of inner cylindrical portion 182, which forms impeller accommodation space 180s, when rotor 150 rotates.

[0069] As described above, motor 170 is an inner rotor type three-phase brushless DC motor composed of stator 160 and rotor 150. However, motor 170 is not limited to a three-phase brushless DC motor, and may be other motors such as a single-phase brushless DC motor.

[0070] Impeller

[0071] like Figure 2 As shown, the impeller 140 is a molded product formed by injection molding of a thermoplastic resin material such as PPS (polyphenylene sulfide).

[0072] The impeller 140 includes: a cylindrical impeller main body 141 extending along the X-axis direction (direction of arrows ab); a disc-shaped base 142 integrally formed at the end of the upper side (direction of arrow a) of the impeller main body 141; a bulge 143 bulging smoothly toward the upper side (direction of arrow a) in the center part of the base 142; and a plurality of blades 145 standing upright around the bulge 143 and on the base 142.

[0073] The impeller 140 includes an impeller body 141, a base 142, a bulged portion 143, and a plurality of blades 145, all formed integrally. However, the present invention is not limited thereto, and the impeller body 141 and the base 142 may be formed separately and then welded together.

[0074] The impeller body (rotor body) 141 is formed of a cylindrical body having a predetermined outer diameter and is accommodated in an impeller accommodation space 180 s formed inside the inner cylindrical portion 182 of the stator holder 180 .

[0075] The impeller body 141 has a concave annular recess on its outer circumference, to which the rotor magnet 159 is fixed by bonding or other means. The rotor magnet 159 is composed of a permanent magnet and is divided into regions magnetized to the south pole and regions magnetized to the north pole, and is arranged alternately along the circumferential direction.

[0076] Alternatively, the rotor magnet 159 may be injection-molded using a resin material containing magnetic powder, and the impeller body 141 , the base 142 , and the blades 145 may be injection-molded using a resin material not containing magnetic powder, and then the two may be combined.

[0077] The outer diameter of rotor magnet 159 is the same as that of impeller body 141, and the outer circumference of rotor magnet 159 is flush with the outer circumference of impeller body 141. It should be noted that the outer diameters of impeller body 141 and rotor magnet 159 are large enough to prevent contact with the inner circumference of inner cylindrical portion 182 of stator holder 180. The key point is that impeller body 141 can rotate without contacting inner cylindrical portion 182 of stator holder 180 when impeller 140 rotates.

[0078] The base 142 is a thin disc-shaped member formed integrally with the upper end (in the direction of arrow a) of the impeller body 141. The outer diameter of the base 142 is smaller than the inner diameter of the impeller accommodation space 180s.

[0079] The impeller body 141 has a through-hole 141h extending through the impeller body 141 at its center along the X-axis direction (directions indicated by arrows ab). The inner diameter of the through-hole 141h is slightly larger than the outer diameter of the shaft 165, which will be described later. In this case, the inner circumferential surface of the through-hole 141h of the impeller body 141 in the impeller 140 and the outer circumferential surface of the shaft 165 function as a sleeve bearing.

[0080] Thus, the impeller 140 is rotatable relative to the shaft 165 fixed to the inner disk portion 185 of the stator holder 180. Note that the present invention is not limited thereto, and a cylindrical sintered bearing may be provided in the impeller body 141.

[0081] The plurality of blades 145 are radially arranged around the bulge 143 with the shaft 165 serving as the rotation axis as the center. Figure 3 As shown, the blade 145 is curved in an arc shape, and its height gradually decreases as it moves away from the shaft 165 in the radial direction (direction of arrow c) (refer to FIG. Figure 2 In this case, for example, seven blades 145 are provided, but the present invention is not limited thereto and may have another number of blades.

[0082] The plurality of blades 145 all have the same structure and shape. When the impeller 140 rotates in the clockwise direction (indicated by the thick arrow) in the figure, the blades 145 and Figure 3 The surface facing the shaft 165 (not shown) is the suction side surface 145a, and the surface facing away from the suction side surface 145a is the pressure side surface 145b. The suction side surface 145a and the pressure side surface 145b of the blade 145 have the same curvature.

[0083] like Figure 4 As shown, the negative pressure side surface 145a at the inner end portion (hereinafter referred to as the "inner end portion") 145t of the blade 145 has an inclined surface 146 formed at a predetermined inclination angle.

[0084] like Figure 4 As shown, the inclined surface 146 is inclined, for example, so that the narrower angle (hereinafter referred to as the "narrow angle") formed by the tangent line TL1 of the center line 145L with respect to the thickness direction of the blade 145 and the tangent line TL2 of the imaginary circle ic connecting the inclined surfaces 146 of the seven blades 145 is 28 degrees. Here, the imaginary circle ic follows the inflow angle of the fluid flowing in from the inflow portion 123.

[0085] In addition, if Figure 5As shown, the inclined surface 146 may be inclined, for example, in the following manner: the narrower angle (hereinafter referred to as the "narrow angle") formed by the tangent TL3 of the center line 145L relative to the thickness direction of the blade 145 and the tangent TL4 of the imaginary circle ic connecting the inclined surfaces 146 of the seven blades 145 to each other is 38 degrees.

[0086] Therefore, the inner diameter of the inflow portion 123 is the same as the inner diameter of the imaginary circle ic. Figure 4 and Figure 5 As shown, when the imaginary circle ic contacts the inclined surface 146 at an inclination angle of 28 degrees or an inclination angle of 38 degrees, the inclined surface 146 does not collide with the fluid flowing in from the inflow portion 123. However, the inclination angle is preferably 28 to 38 degrees, but is not limited thereto.

[0087] Thus, the negative pressure side surface 145a of the inner end portion 145t of the blade 145 has the inclined surface 146 formed at an inclined angle of 28 degrees or 38 degrees, thereby reducing collision loss with the fluid and improving pump efficiency.

[0088] In addition, if Figure 3 As shown, the bulged portion 143 of the impeller 140 has three circular through-holes 143h arranged approximately 120 degrees apart in a plan view around the axis 165. The three through-holes 143h are provided radially inward of the inclined surface 146.

[0089] like Figure 2 As shown, in the impeller main body 141 of the impeller 140, a bottomed cylindrical recessed space 141r is provided at a position corresponding to the through hole 143h of the bulging portion 143 in the up and down directions (directions of arrows ab) with the axis 165 as the center. The recessed space 141r is connected to the through hole 143h of the bulging portion 143.

[0090] As described above, the through-hole 143h of the bulged portion 143 and the recessed space 141r of the impeller body 141 are connected to each other. Therefore, the space on the upper side (in the direction of arrow a) where the plurality of blades 145 are provided and the space on the lower side (in the direction of arrow b) where the plurality of blades 145 are not provided, with the base 142 of the impeller 140 as the boundary, are connected (communicated) to each other via the through-hole 143h and the recessed space 141r.

[0091] <Water Pump Operation and Effect>

[0092] In the water pump 100 , the impeller body (rotor body) 141 of the impeller 140 rotates about the shaft 165 due to electromagnetic interaction between the rotor 150 and the stator 160 of the motor 170 .

[0093] Thus, in the water pump 100 , the blades 145 rotate together with the impeller body 141 , and the plurality of blades 145 can pressurize the fluid flowing in from the inlet 123 from the outflow portion 125 on the radially outer side (in the direction of arrow c).

[0094] In the water pump 100 , an inclined surface 146 is provided on the negative pressure side surface 145 a of the inner end portion 145 t of the plurality of blades 145 in the impeller 140 , and a plurality of through holes 143 h are provided in the bulged portion 143 of the base 142 so as to be adjacent to the inclined surface 146 .

[0095] Thus, the water pump 100 can reduce collision loss with the fluid flowing in from the inflow portion 123 by the inclined surface 146 provided on the negative pressure side surface 145 a of the inner end portion 145 t of the blade 145 , thereby improving pump efficiency.

[0096] At the same time, in the water pump 100, due to the presence of three through holes 143h provided on the bulged portion 143 of the impeller 140, the space on the upper side (in the direction of arrow a) of the base 142 where a plurality of blades 145 are provided is connected to the space on the lower side (in the direction of arrow b) of the base 142 where a plurality of blades 145 are not provided, so that a large pressure difference is not generated between the upper space and the lower space of the base 142.

[0097] In the existing water pump, there is no through hole 143h in the bulge 143 of the impeller 140, and a pressure difference will be generated between the upper space and the lower space of the base 142, which may cause the impeller 140 as a whole to rise upward along the shaft 156 (in the direction of arrow a) and contact the inner circumferential surface of the upper shell body 121.

[0098] However, the water pump 100 does not generate a pressure difference between the upper and lower spaces of the base 142 , thereby preventing the impeller 140 from rising upward (in the direction of arrow a) relative to the shaft 156 and contacting the upper casing body 121 .

[0099] Thus, in the water pump 100 , the impeller 140 can stably rotate without coming into contact with the upper casing body 121 , and thus the pump efficiency can be reliably improved accordingly.

[0100] In fact, if Figure 6 and Figure 7 As shown, the PQ performance and pump efficiency were verified when the inclined surface 146 provided on the negative pressure side surface 145a of the inner end portion 145t of the blade 145 had an inclination angle of 28 degrees. In this case, the verification was also conducted simultaneously with the case where the inclined surface 146 with an inclination angle of 28 degrees was provided only on the pressure side surface 145b of the blade 145 and the case where the inclined surface 146 with an inclination angle of 28 degrees was provided on both the pressure side surface 145b and the negative pressure side surface 145a as comparison objects.

[0101] In this case, if Figure 6 The line chart of (A) and Figure 6 As shown in the bar graph of (B), it is shown that when the outflow amount from the outflow portion 125 is medium (M), the static pressure [Pa] is the highest when the inclined surface 146 is provided only on the negative pressure side surface 145a.

[0102] In addition, if Figure 7 The line chart of (A) and Figure 7 The bar graph (B) shows that the pump efficiency is highest when the outflow from the outflow portion 125 is medium (M), also when only the inclined surface 146 is provided on the negative pressure side surface 145a. Pump efficiency here refers to the ratio of the axial power input from the drive shaft (in this case, the impeller 140 and the impeller body 141) to the hydraulic power output from the water pump 100.

[0103] Likewise, if Figure 8 and Figure 9 As shown, the PQ performance and pump efficiency were verified when the inclined surface 146 provided on the negative pressure side surface 145a of the inner end portion 145t of the blade 145 had an inclination angle of 38 degrees. In this case, the case where the inclined surface 146 with an inclination angle of 38 degrees was provided only on the pressure side surface 145b of the blade 45 and the case where the inclined surface 146 with an inclination angle of 38 degrees was provided on both the pressure side surface 145b and the negative pressure side surface 145a were also compared and verified.

[0104] In this case, if Figure 8 The line chart of (A) and Figure 8 As shown in the bar graph of (B), it is shown that when the outflow amount from the outflow portion 125 is medium (M), the static pressure [Pa] is the highest when the inclined surface 146 is provided only on the negative pressure side surface 145a.

[0105] In addition, if Figure 9 (A) Line chart and Figure 9 As shown in the bar graph (B), when the outflow amount from the outflow portion 125 is medium (M), the pump efficiency is highest when the inclined surface 146 is provided only on the negative pressure side surface 145a.

[0106] As described above, in the water pump 100, the presence of the inclined surface 146 provided on the negative pressure side surface 145a of the inner end portion 145t of the blade 145 and the three through holes 143h provided on the bulged portion 143 of the impeller 140 can improve pump efficiency compared to the conventional method.

[0107] <Other Implementation Methods>

[0108] As mentioned above, although the water pump of the present invention has been described by giving examples of preferred embodiments, the water pump of the present invention is not limited to the configuration of the above-mentioned embodiments.

[0109] It should be noted that, in the embodiment of the impeller 140, the case where three through holes 143h are provided in the bulging portion 143 is described, but the present invention is not limited thereto. Figure 10 As shown, seven through holes 143h, which is the same number as the seven blades 145, or a multiple of the number of through holes 143h, such as fourteen or twenty-one, may be provided. When the number of through holes 143h is increased, the inner diameter of the through holes 143h can be reduced to adjust the pressure difference between the upper and lower spaces of the base 142 of the impeller 140.

[0110] For example, when seven through holes 143h are provided, they may be arranged circumferentially opposite to the inclined surface 146 of the blade 145. However, the present invention is not limited thereto, and the seven through holes 143h may be arranged radially opposite to the inclined surface 146 of the blade 145.

[0111] Furthermore, when fourteen through-holes are provided, they may be arranged two by two so as to sandwich the inner end portion 145t of the blade 145 in the radial direction. However, the present invention is not limited thereto, and the fourteen through-holes 143h may be arranged two by two in the circumferential direction opposite to the inclined surface 146 of the blade 145, or may be arranged two by two in the radial direction opposite to the inclined surface 146 of the blade 145.

[0112] In addition, in the impeller 140 of the embodiment, the case where three circular through holes 143h are provided in the bulging portion 143 is described, but the present invention is not limited thereto. Figure 11 As shown, a plurality of (three in this case) oblong through holes 283h may be provided along the circumferential direction.

[0113] In this case, if Figure 12 As shown, the inclined surface 146 of the blade 145 is in line contact with the through hole 283h, and the pressure difference between the upper space and the lower space of the base 142 of the impeller 140 can be adjusted by only a small number of through holes 283h.

[0114] Moreover, in the impeller 140, a structure is described in which the impeller body 141 is a part of the impeller 140 and is integrally provided with the base 142, the bulge 143 and the blades 145 as a part of the rotor 150, but the present invention is not limited to this. The rotor 150 and the impeller 140 can also be formed as different parts and then combined into one by welding or the like.

[0115] Furthermore, in the embodiment, the water pump 100 is described as being mounted in an engine room, etc., but the present invention is not limited thereto and can also be used to forcibly circulate cooling water relative to electric equipment such as inverters in hybrid vehicles and electric vehicles that have become popular in recent years.

[0116] Furthermore, those skilled in the art may make appropriate changes to the water pump of the present invention or modify the combination of various features according to prior art knowledge. As long as the features of the present invention are still possessed through such changes, they are naturally included in the scope of the present invention.

[0117] Description of Reference Numerals

[0118] 100: Water pump; 120: Upper casing; 121: Upper casing main body; 121p: Projection; 123: Inflow portion; 124: Shaft support portion; 124a: Arm portion; 124d: Flange portion; 124p: Shaft support portion; 125: Outflow portion; 130: Lower casing; 130s: Stator accommodating space; 131: Lower casing main body; 132: Flange portion; 135: Flange; 140: Impeller; 141: Impeller main body (rotor main body); 142: Base; 143: Bulging portion; 145: Blades; 150: Rotor; 159: Rotor magnet; 160: Stator; 161: Stator core; 162: Insulator; 163: Coil; 165: Shaft; 170: Motor; 180s: Impeller accommodating space.

Claims

1. A water pump comprising: a housing having an inflow portion for a fluid and an outflow portion for the fluid; and an impeller rotatably supported inside the housing, The impeller comprises a base and a plurality of blades arranged on the base. The blade has a negative pressure side and a pressure side relative to the fluid, An inclined surface is provided at an inner peripheral end portion of the negative pressure side surface, the inclined surface being formed to be inclined at a predetermined angle so as to follow an inflow angle of the fluid flowing in from the inflow portion. The base has a through hole adjacent to the inclined surface in an extending direction of the blade.

2. The water pump according to claim 1, The through hole connects a space on the blade side relative to the base and a space on the opposite side of the base relative to the blade side.

3. The water pump according to claim 1 or 2, The through hole is provided on an inner side relative to the inclined surface in a radial direction.

4. The water pump according to claim 1, The number of the through holes is the same as the number of the plurality of blades or is a multiple of the number of the plurality of blades.

5. The water pump according to claim 1, The through hole is circular or arc-shaped.

6. The water pump according to claim 5, The through hole is arranged along the inclined surface.

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