Motor

Abstract

A water pump (1), which is an example of a motor, comprises: a shaft (3); a cylinder (bearing) (7) rotatably supported by the shaft (3); an impeller (6) fixed to the cylinder (7); a rotor (5) fixed to the impeller (6); a stator (4) surrounding the rotor (5); and a space (2s1) between the shaft (3) and the cylinder (7). The cylinder (7) is provided with one end (71) and the other end (72) in the rotation axis direction. The inner surface (7f1) of the cylinder (7) is formed with one or a plurality of grooves (7G1) extending in the rotation axis direction of the cylinder (7). The grooves (7G1) extend continuously from the one end (71) of the cylinder (7) to the other end (72).

Description

motor

[0001] The present invention relates to a motor.

[0002] In motors used in water pumps and the like that circulate liquid using an impeller, a technique is known in which dynamic pressure grooves are formed in the bearings to obtain a dynamic pressure effect from the circulating liquid (see, for example, Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2022-52709

[0004] However, the motor described in Patent Document 1 has room for improvement in terms of ensuring smooth circulation of the liquid inside.

[0005] One aspect of the present invention is to provide a motor that allows smooth circulation of liquid inside.

[0006] In one aspect, the motor comprises a shaft, a cylinder rotatably supported on the shaft, an impeller fixed to the cylinder, a rotor fixed to the impeller, a stator surrounding the rotor, and a space between the shaft and the cylinder, wherein the cylinder has one end and the other end in the direction of the rotation axis, and one or more grooves extending in the direction of the rotation axis of the cylinder are formed on the inner surface of the cylinder, and the grooves extend continuously from one end to the other end of the cylinder.

[0007] According to one aspect, the motor can ensure smooth circulation of the liquid therein.

[0008] FIG. 1 is a perspective view of a water pump according to this embodiment. FIG. 2 is a plan view of the water pump shown in FIG. 1. FIG. 3 is an exploded perspective view of the water pump shown in FIG. 1. FIG. 4 is a perspective view including a cross-sectional view taken along arrows A-A in FIG. 2. FIG. 5 is a perspective view of a second casing provided in the water pump shown in FIG. 1. FIG. 6 is a cross-sectional view showing the flow of liquid when the water pump shown in FIG. 1 is operated. FIG. 7 is a perspective view showing a cylinder provided in the water pump shown in FIG. 1. FIG. 8 is a vertical cross-sectional view of the cylinder shown in FIG. 7. FIG. 9 is a horizontal cross-sectional view of the cylinder shown in FIG. 7. FIG. 10 is a perspective view including a horizontal cross-section of the cylinder shown in FIG. 7.

[0009] [Embodiment] A water pump 1, which is an example of an embodiment of a motor according to the present invention, will be described in detail below with reference to the drawings. Note that the dimensional relationships and ratios of elements in the drawings may differ from the actual situation. The dimensional relationships and ratios may also differ between the drawings.

[0010] For ease of explanation, the following description will use the mutually perpendicular X-axis, Y-axis, and Z-axis directions. The X-axis direction is, for example, the extension direction (rotational axis direction) of the axis 3x of the shaft 3 included in the water pump 1. In addition, in the water pump 1 according to this embodiment, for example, the direction in which the liquid circulating inside is sucked in is the positive X-axis direction, and the direction in which the liquid is discharged is the positive Z-axis direction.

[0011] First, the configuration of a water pump 1 according to this embodiment will be described with reference to FIGS. 1 to 5. FIG. 1 is a perspective view of the water pump 1 according to this embodiment. FIG. 2 is a plan view of the water pump 1 shown in FIG. 1. FIG. 3 is an exploded perspective view of the water pump 1 shown in FIG. 1. FIG. 4 is a perspective view including a cross-sectional view taken along arrows A-A in FIG. 2. FIG. 5 is a perspective view of a second casing 22 included in the water pump 1 shown in FIG. 1.

[0012] The water pump 1 of this embodiment includes a case 2, a shaft 3, a stator 4, a rotor 5, an impeller 6, and a cylinder 7 (see FIGS. 3 and 4).

[0013] 4 is made of, for example, resin and includes a first case 21 located on the negative side of the X axis, a second case 22 located on the positive side of the X axis, and an O-ring 23. The first case 21 is fixed to the second case 22 in a watertight manner in the X axis direction with the O-ring 23 interposed therebetween, thereby forming an internal space 2s within the case 2 and forming an outer shell of the water pump 1. In the water pump 1 according to this embodiment, liquid (coolant) circulates within the internal space 2s of the water pump 1.

[0014] In other words, the water pump 1 accommodates the rotor 5 and impeller 6 inside a case 2 made up of a first case 21 , a second case 22 and an O-ring 23 , and circulates liquid inside the case 2 .

[0015] The first case 21 shown in FIGS. 1 to 3 includes an intake port 21a for drawing liquid into the internal space 2s of the water pump 1 and an outlet port 21b for discharging the liquid from the internal space 2s of the water pump 1. The water pump 1 according to this embodiment uses a liquid (coolant). The liquid circulating inside the water pump 1 is, for example, a liquid with a specific gravity heavier than that of water (e.g., propylene glycol). In other words, the density of the liquid used in the water pump 1 is greater than the density of air. Furthermore, the viscosity coefficient of the liquid used in the water pump 1 is greater than the viscosity coefficient of air.

[0016] As shown in Fig. 4, the second case 22 includes a bottom wall 22a, an inner wall 22b, a top wall 22c, and an outer wall 22d. The second case 22 includes a first cup-shaped recess formed by the bottom wall 22a and the inner wall 22b and opening toward the negative side of the X-axis. The second case 22 also includes a second cup-shaped recess formed by the inner wall 22b, the top wall 22c, and the outer wall 22d and opening toward the positive side of the X-axis. The stator core 41 and the coil 42 are disposed in the second recess, and the rotor 5 is disposed in the first recess.

[0017] Bottom wall 22a is formed in a generally annular shape with a plane perpendicular to the X-axis direction. Inner wall 22b extends from the radially outer edge of bottom wall 22a about axis 3x toward the negative X-axis direction. Top wall 22c extends from the radially outer edge of inner wall 22b about axis 3x toward the negative X-axis direction. Outer wall 22d extends radially inward from axis 3x with a predetermined space between it and the radially outer edge of top wall 22c about axis 3x.

[0018] In the water pump 1 according to this embodiment, the inner wall 22b of the second case 22 forms the inner surface of the stator 4. That is, the second case 22 according to this embodiment cooperates with the first case 21 to form the outer shell of the case 2, and cooperates with a stator core 41 and a coil 42 (described later) to form the stator 4.

[0019] A through hole 2H is formed in bottom wall 22a, through which shaft 3 is inserted and fixed. Note that, in order to improve the watertightness of internal space 2s, a recess that supports shaft 3 from the X-axis positive direction side may be formed in bottom wall 22a instead of through hole 2H.

[0020] 4 and 5, the inner wall 22b has inner peripheral surfaces 22f1 and 22f2 that are inclined at different angles relative to the axis 3x. A plurality of dynamic pressure grooves 22G are formed in the inner wall 22b.

[0021] The dynamic pressure grooves 22G are arranged, for example, at equal intervals in the circumferential direction of the axis 3x. Each of the dynamic pressure grooves 22G according to this embodiment is formed in a V-shape having a vertex 22GP when viewed from the side in the Z-axis direction, as shown in FIG.

[0022] Each dynamic pressure groove 22G has a first portion 22G1 located on the negative X-axis side of the apex 22GP and a second portion 22G2 located on the positive X-axis side of the apex 22GP. The first portion 22G1 and the second portion 22G2 extend so as to be inclined with respect to the X-axis direction. More specifically, the first portion 22G1 and the second portion 22G2 are inclined with respect to the X-axis direction in opposite directions.

[0023] The O-ring 23 shown in FIG. 3 is formed into an annular shape from an elastic material such as rubber.

[0024] The shaft 3 is formed of, for example, a metal material in a cylindrical shape and extends, for example, in the X-axis direction.

[0025] The stator 4 is a part that generates a force for rotating the rotor 5. In the water pump 1 according to this embodiment, the stator 4 is disposed radially outward of the rotor 5. In other words, the stator 4 surrounds the rotor 5 from the radially outward side. The stator 4 includes a stator core 41 and a plurality of coils 42.

[0026] The stator core 41 extends in the X-axis direction around the axis 3x of the shaft 3. The stator core 41 is composed of a plurality of magnetic members (an example of a magnetic material). The magnetic members are formed into a plate shape using metal, such as soft magnetic steel plate (e.g., silicon steel plate, electromagnetic steel plate), or amorphous metal. The stator core 41 is formed, for example, by stacking a plurality of such metal plate members in the X-axis direction. As shown in FIG. 4 , the stator core 41 is disposed between the inner wall 22b and the outer wall 22d of the second case 22 in the radial direction relative to the axis 3x of the shaft 3. In other words, the stator core 41 is formed to surround the inner wall 22b of the second case 22. The stator core 41 may also be in contact with the inner wall 22b. In this case, the stator core 41 can be stably fixed.

[0027] 3, the stator core 41 includes a yoke 411 and a plurality of teeth 412. The yoke 411 is a base portion of the stator core 41 and is configured in a cylindrical shape. The outer peripheral surface of the yoke 411 is fixed to the inner peripheral surface of the outer wall 22d. Meanwhile, each of the plurality of teeth 412 protrudes inward from the inner peripheral surface of the yoke 411 in the radial direction of the axis 3x.

[0028] The coils 42 are formed, for example, by winding a conductive wire having a conductive core around the teeth 412. Note that the coils 42 may also be configured such that a wound bobbin coil is fitted onto the teeth 412.

[0029] The rotor 5 is a part that rotates relative to the stator 4. In the water pump 1 according to this embodiment, the rotor 5 is disposed radially inside the stator 4. The rotor 5 includes a rotor core 51 and a magnet 52.

[0030] The rotor core 51 according to this embodiment is formed integrally with, for example, the impeller 6. In other words, the rotor 5 is fixed to the impeller 6. The rotor core 51 according to this embodiment is disposed on the X-axis positive side of the impeller 6 and is formed in a cylindrical shape.

[0031] The magnet 52 is formed in a cylindrical shape. The inner peripheral surface of the magnet 52 is fixed to the outer peripheral surface of the rotor core 51. The magnet 52 is preferably a rare earth magnet such as a neodymium magnet, which has high magnetic properties. The magnet 52 may be formed integrally with the rotor core 51. In the rotor 5 according to this embodiment, the outer peripheral surface of the magnet 52 is an example of the outer surface of the rotor 5.

[0032] A magnetic gap is formed between the teeth 412 shown in Fig. 4 and the magnets 52 of the rotor 5. The stator 4 generates a magnetic field for rotating the magnets 52 of the rotor 5 by sequentially applying externally supplied AC current to the coils 42 wound around each tooth 412. As a result, the magnets 52 of the rotor 5 rotate around the shaft 3 as the rotation axis due to the magnetic field generated in the stator core 41. The stator 4 including the teeth 412 and the rotor including the magnets 52 face each other in the radial direction via the inner wall 22b, thereby forming a magnetic cap.

[0033] The impeller 6 rotates together with the rotor core 51 and the magnet 52 to draw in liquid through the intake port 21a and discharge the liquid through the outlet port 21b. At this time, the magnet 52 and the impeller 6 housed in the second case 22 come into contact with and are immersed in the liquid flowing inside the water pump 1. Meanwhile, the bottom wall 22a, inner wall 22b, and top wall 22c of the second case 22 prevent the liquid from coming into contact with the stator core 41 and the coil 42.

[0034] The impeller 6 includes a plurality of rotor blades 61. In the present embodiment, the rotor blades 61 and the rotor core 51 of the impeller 6 are integrally molded from, for example, resin. Alternatively, the rotor blades 61 and the rotor core 51 of the impeller 6 may be formed separately.

[0035] The tube 7 is formed in a cylindrical shape that is centered on the axis 3x of the shaft 3 and extends in the X-axis direction.

[0036] In addition, the internal space 2s according to this embodiment has at least a first space 2s1, a second space 2s2, and a third space 2s3 through which liquid (coolant) flows when the water pump 1 is operating (see FIG. 6).

[0037] 6 is a gap formed between the inner circumferential surface 7f1 of the cylinder 7 and the outer circumferential surface 3f of the shaft 3 in the radial direction of the axis 3x. The length of the first space 2s1 in the circumferential direction of the axis 3x is, for example, 10 μm. The cylinder 7 according to this embodiment is a fluid bearing in which a liquid is interposed between the inner circumferential surface 7f1 of the cylinder 7 and the outer circumferential surface 3f of the shaft 3 in the radial direction of the axis 3x.

[0038] The second space 2s2 is formed in the X-axis direction between the rotor core 51 and the magnet 52 and the bottom wall 22a.

[0039] The third space 2s3 is formed in the radial direction of the axis 3x between the inner circumferential surface 22f1 of the second case 22 and the outer circumferential surface of the magnet 52. The third space 2s3 is an example of the space between the rotor 5 and the stator 4.

[0040] When the water pump 1 shown in Figure 1 having such a configuration is operated, liquid is drawn into the internal space 2s through the intake port 21a, circulates inside the case 2, and then is discharged from the internal space 2s through the exhaust port 21b.

[0041] The flow of liquid when the water pump 1 having the above configuration is in operation will now be described with reference to Figure 6. Figure 6 is a cross-sectional view showing the flow of liquid when the water pump 1 shown in Figure 1 is in operation.

[0042] Liquid drawn into the internal space 2s of the water pump 1 from the suction port 21a flows radially outward from the axis 3x of the shaft 3 due to the pressure of the impeller 6 rotating in the circumferential direction about the axis 3x, and some of the liquid flows radially from the axis 3x into a first space 2s1 formed between the inner circumferential surface 7f1 of the cylinder 7 and the outer circumferential surface 3f of the shaft 3. In other words, the cylinder 7 according to this embodiment is a fluid bearing that is supported on the shaft 3 with liquid interposed therebetween in the radial direction of the axis 3x.

[0043] In this case, the liquid that has flowed into the first space 2s1 flows in the positive direction of the X axis as indicated by arrow A1 in FIG. 6, and flows into the second space 2s2 between the rotor core 51 and magnet 52 and the bottom wall 22a.

[0044] Next, the liquid that has flowed into the second space 2s2 flows from the inside to the outside in the radial direction of the axis 3x, as indicated by an arrow A2 in FIG.

[0045] Next, the liquid in the second space 2s2 flows in the negative direction of the X-axis through the third space 2s3 formed between the second case 22 and the magnet 52, as shown by arrow A3 in Figure 6, due to the dynamic pressure groove 22G formed in the inner wall 22b of the second case 22.

[0046] Thereafter, the pressure of the rotating impeller 6 causes the liquid to flow outward in the radial direction of the axis 3x, and is discharged from the discharge port 21b.

[0047] In the second space 2s2 of the water pump 1, dynamic pressure is not easily generated, and the liquid that flows in tends to stagnate. In the water pump 1 according to this embodiment, the dynamic pressure grooves 22G make it easier for the liquid to flow toward the negative X-axis direction. In this case, by forming the dynamic pressure grooves 22G in the second case 22, whose radial length relative to the axis 3x is longer than that of the magnet 52, a higher dynamic pressure can be obtained, thereby increasing the amount of liquid that can be sucked from the second space 2s2 to the third space 2s3.

[0048] The water pump 1 according to this embodiment includes a cylinder 7 having the following configuration to ensure smooth circulation of liquid in the internal space 2s of the case 2. The configuration of the cylinder 7 will now be described. FIG. 7 is a perspective view showing an example of the cylinder 7 included in the water pump 1 shown in FIG. 1 . FIG. 8 is a vertical cross-sectional view of the cylinder shown in FIG. 7 . FIG. 9 is a horizontal cross-sectional view of the cylinder 7 shown in FIG. 7 . FIG. 10 is a perspective view including a horizontal cross-section of the cylinder 7 shown in FIG. 7 .

[0049] 7 and 8 , the tube 7 includes a pair of end portions 71, 72 and a central portion 73 in the X-axis direction. The tube 7 also includes an inner circumferential surface 7f1 and an outer circumferential surface 7f2 in the radial direction relative to the axis 3x. In the tube 7 according to this embodiment, for example, the pair of end portions 71, 72 and the central portion 73 are integrally formed.

[0050] The cylinder 7 is supported by the impeller 6 and the rotor core 51 so as to be rotatable about the shaft 3. More specifically, the outer peripheral surface 7f2 of the cylinder 7 is fixed to the inner peripheral surface of the impeller 6 and the inner peripheral surface of the rotor core 51, and the cylinder 7 rotates together with the impeller 6 and the rotor 5.

[0051] One end 71 of the pair of end portions 71, 72 is located on the negative side of the X-axis. The other end 72 of the pair of end portions 71, 72 is located on the positive side of the X-axis. The pair of end portions 71, 72 function as bearings. The central portion 73 is located between the one end portion 71 and the other end portion 72 in the X-axis direction.

[0052] A first groove 7G1 and a second groove 7G2 are formed in the inner circumferential surface (inner surface) 7f1 of the cylinder 7. The first groove 7G1 and the second groove 7G2 are examples of dynamic pressure grooves.

[0053] For example, a plurality of first grooves 7G1 are formed on the inner circumferential surface 7f1 of the cylinder 7. According to this embodiment, a plurality of (for example, three) first grooves 7G1 are formed on the inner circumferential surface 7f1 of the cylinder 7. Note that only one first groove 7G1 may be formed on the inner circumferential surface 7f1 of the cylinder 7.

[0054] The multiple first grooves 7G1 are arranged, for example, at equal intervals in the circumferential direction of the axis 3x. Each of the first grooves 7G1 extends in the X-axis direction (rotational axis direction) of the tube 7. Furthermore, each of the first grooves 7G1 extends continuously from one end 71 to the other end 72 of the tube 7 in the X-axis direction. More specifically, each of the first grooves 7G1 extends continuously from one end surface 7f3 to the other end surface 7f4 of the tube 7 in the X-axis direction. The first grooves 7G1 according to this embodiment extend linearly, for example, along the rotational axis direction.

[0055] For example, multiple second grooves 7G2 are formed on the inner circumferential surface 7f1 of the first end 71 of the tube 7, and multiple second grooves 7G2 are formed on the inner circumferential surface 7f1 of the second end 72 of the tube 7. In the tube 7 according to this embodiment, the configuration of one end 71 and the configuration of the other end 72 are identical except for their different lengths in the X-axis direction. Therefore, to avoid repetition, the configuration of the one end 71 will be described below, and the description of the configuration of the other end 72 will be omitted, with the same reference numerals used. Specifically, regarding the one end 71 and the other end 72 described as having different lengths, the length of the other end 72 in the X-axis direction is longer than the length of the one end 71 in the X-axis direction. In other words, the length of the other end 72 on the opposite side of the suction port 21a of the water pump 1 in the X-axis direction is longer than the length of the one end 71 on the suction port 21a side.

[0056] The second grooves 7G2 are formed, for example, only at one end 71 and the other end 72, and are not formed in the central portion 73. In other words, the water pump 1 according to this embodiment includes two second grooves 7G2 spaced apart in the X-axis direction (axial direction).

[0057] Each of the multiple second grooves 7G2 is formed in a V-shape having a vertex 72GP in a side view seen from the Z-axis direction. That is, the shape of the first groove 7G1 and the shape of the second groove 7G2 are different. Each second groove 7G2 has a first portion 7211 located on the negative X-axis side of the vertex 72GP and a second portion 7212 located on the positive X-axis side of the vertex 72GP. The first portion 7211 and the second portion 7212 are arranged so as to be line-symmetric with respect to a plane that passes through the vertex 72GP and is perpendicular to the X-axis.

[0058] That is, the second grooves 7G2 according to this embodiment extend so as to be inclined with respect to the X-axis direction (rotation axis direction). In other words, the second grooves 7G2 extend in the circumferential direction.

[0059] The second grooves 7G2 are arranged such that the apexes 72GP are spaced at equal intervals in the circumferential direction of the axis 3x.

[0060] The V-shaped second groove 7G2 is formed to coincide with the rotation direction of the impeller 6. More specifically, with respect to the rotation direction of the impeller 6, the apex 72GP of the second groove 7G2 is located on the rotation direction side of the impeller 6, and the first portion 7211 and the second portion 7212 with respect to the apex 72GP are located on the opposite side of the rotation direction of the impeller 6.

[0061] Furthermore, the dynamic pressure grooves formed in the cylinder 7 and serving as the second grooves 7G2 and the dynamic pressure grooves 22G formed in the second case 22 are curved in different directions in the circumferential direction relative to the axis 3x of the shaft 3. More specifically, in a side view taken along the Z axis, the second grooves 7G2 extend from the apex 72GP toward the negative Z direction, as shown in FIG. 8 . On the other hand, in a side view taken along the Z axis, the dynamic pressure grooves 22G extend from the apex 22GP toward the positive Z direction, as shown in FIG. 5 . As a result, in the impeller 6 rotating in one direction, the second grooves 7G2 cause liquid to flow toward the positive X direction in the first space 2s1, and the dynamic pressure grooves 22G cause liquid to flow toward the negative X direction in the second space 2s2.

[0062] The first groove 7G1 extends in the X-axis direction (rotation axis direction) across each of the two second grooves 7G2.

[0063] The width W1 of the first groove 7G1 shown in Fig. 9 perpendicular to the extension direction is larger than the width W2 of the second groove 7G2 shown in Fig. 10 perpendicular to the extension direction. In other words, the width W1 of the first groove 7G1 is larger than the width W2 of the second groove 7G2. More specifically, the width of the first groove 7G1 is, for example, 500 µm. The width of the second groove 7G2 is, for example, 15 µm.

[0064] The depth D1 of the first groove 7G1 relative to the imaginary inner circumferential surface 7f1 of the tube 7 is greater than the depth D2 of the second groove 7G2 relative to the imaginary inner circumferential surface 7f1 of the tube 7. In other words, the depth D1 of the first groove 7G1 is greater than the depth D2 of the second groove 7G2. The depth D1 of the first groove 7G1 is, for example, 250 μm. The depth D2 of the second groove 7G2 is, for example, 15 μm.

[0065] The cross section of the first groove 7G1 perpendicular to the extension direction has, for example, a substantially semicircular shape, whereas the cross section of the second groove 7G2 perpendicular to the extension direction has, for example, a substantially rectangular shape.

[0066] A first groove 7G1 extending in the X-axis direction (rotation axis direction) of the tube 7 is formed on the inner peripheral surface (inner surface) 7f1 of the tube 7, and the first groove 7G1 extends continuously from one end 71 to the other end 72 of the tube 7. Therefore, the first groove 7G1 allows the liquid in the first space 2s1 to flow smoothly toward the positive X-axis direction. The first groove 7G1 connects the second space 2s2 and the first space 2s1, and the first space 2s1 is in communication with the internal space 2s. The liquid drawn in from the suction port 21a flows into the first space 2s1 via the internal space 2s. The second space 2s2 and the internal space 2s are in communication with each other via the first groove 7G1, allowing the liquid to flow.

[0067] Furthermore, the inner peripheral surface (inner surface) 7f1 of the tube 7 is provided with two second grooves 7G2 extending circumferentially and a first groove 7G1 extending in the X-axis direction (rotation axis direction) across the second groove 7G2, one of the two second grooves 7G2 being formed at one end 71 of the tube 7, and the other of the two second grooves 7G2 being formed at the other end 72 of the tube 7.

[0068] If only the second grooves 7G2 were formed on the inner circumferential surface 7f1 of the cylinder 7, foreign matter contained in the liquid might accumulate at locations where the vertices 72GP are spaced apart in the circumferential direction. On the other hand, the first grooves 7G1 of the cylinder 7 according to this embodiment extend in the X-axis direction (rotation axis direction) across the second grooves 7G2, and therefore, it is possible to prevent foreign matter from accumulating at locations where the vertices 72GP are spaced apart in the circumferential direction.

[0069] Furthermore, while foreign matter may accumulate in the first space 2s1 as described above, the water pump 1 according to this embodiment has the first groove 7G1, which is a dynamic pressure groove, which makes it easier for the liquid containing foreign matter to flow toward the positive direction of the X axis. In this case, by forming the first groove 7G1, which is a dynamic pressure groove, in the cylinder 7, whose radial length relative to the axis 3x is longer than that of the shaft 3, a higher dynamic pressure can be obtained, allowing the liquid to flow smoothly from the first space 2s1 to the second space 2s2.

[0070] As described above, the water pump 1 according to this embodiment includes the shaft 3, the cylinder 7 rotatably supported on the shaft 3, the impeller 6 fixed to the cylinder 7, the rotor 5 fixed to the impeller 6, the stator 4 surrounding the rotor 5, and the first space 2s1 between the shaft 3 and the cylinder 7. The cylinder 7 has one end 71 and the other end 72 in the rotational axis direction. One or more first grooves 7G1 extending in the rotational axis direction of the cylinder 7 are formed in the inner circumferential surface (inner surface) 7f1 of the cylinder 7. The first grooves 7G1 extend continuously from the one end 71 to the other end 72 of the cylinder 7. Therefore, the circulation of the liquid (coolant) in the water pump 1 is smooth, preventing foreign matter from accumulating in the first space 2s1 and allowing foreign matter to be discharged to the outside of the first space 2s1. Therefore, the water pump 1 according to this embodiment can prevent foreign matter from clogging the first space 2s1, thereby improving reliability.

[0071] In the water pump 1 according to this embodiment, the inner peripheral surface (inner surface) 7f1 of the cylinder 7 facing the shaft 3 is provided with two second grooves 7G2 extending in the circumferential direction and a first groove (groove) 7G1 extending in the rotational axis direction across the two second grooves 7G2, with one of the two second grooves 7G2 being formed at one end 71 of the cylinder 7 and the other of the two second grooves 7G2 being formed at the other end 72 of the cylinder 7. In the water pump 1 according to this embodiment, the first groove 7G1 of the cylinder 7 extends in the X-axis direction (rotational axis direction) across the second groove 7G2, thereby preventing foreign matter from accumulating at locations where the vertices 72GP are spaced apart in the circumferential direction.

[0072] In the water pump 1 according to this embodiment, the first space (space) 2s1 contains a liquid (coolant).

[0073] Furthermore, in the water pump 1 according to this embodiment, matter (foreign matter) other than liquid passes through the first groove (groove) 7G1 extending in the rotational axis direction.

[0074] Furthermore, in the water pump 1 according to this embodiment, the width of the first groove (groove) 7G1 extending in the rotational axis direction is greater than the width of the second groove 7G2 extending in the circumferential direction.

[0075] Furthermore, in the water pump 1 according to this embodiment, the depth of the first groove (groove) 7G1 extending in the rotational axis direction is greater than the width of the second groove 7G2 extending in the circumferential direction.

[0076] In the water pump 1 according to the present embodiment described above, three first grooves 7G1 are formed in the inner circumferential surface 7f1 of the cylinder 7. However, the number of first grooves 7G1 according to the present embodiment is not limited to this. For example, one first groove 7G1, two first grooves 7G1, or four or more first grooves 7G1 may be formed in the inner circumferential surface 7f1 of the cylinder 7.

[0077] Furthermore, in the water pump 1 according to the present embodiment described above, the plurality of dynamic pressure grooves 22G are formed in the inner circumferential surfaces 22f1, 22f2 of the second case 22. However, the water pump 1 according to the present embodiment is not limited to this, and instead of forming the dynamic pressure grooves 22G in the inner circumferential surfaces 22f1, 22f2 of the second case 22, the plurality of dynamic pressure grooves may be formed in the outer circumferential surface of the magnet 52.

[0078] Furthermore, the water pump 1 according to the present embodiment has been described as having the dynamic pressure grooves 22G extending to the inner circumferential surfaces 22f1 and 22f2 of the second case 22. However, the water pump 1 according to the present embodiment is not limited to this, and the dynamic pressure grooves 22G may be formed only on the inner circumferential surface 22f1 of the second case 22, with no dynamic pressure grooves 22G formed on the inner circumferential surface 22f2.

[0079] Furthermore, although the above-described case has been described in which one tube 7 is provided for one shaft 3, two or more tubes may be provided. In this case, for example, two tubes 7 may be disposed at both ends of the axis 3x of the shaft 3 in the X-axis direction. Furthermore, when two or more tubes 7 are provided on the shaft 3, the multiple tubes 7 may be in contact with each other in the X-axis direction, or the multiple tubes 7 may be spaced a predetermined distance apart in the X-axis direction.

[0080] The above description is based on an embodiment of the water pump 1 according to the present invention, but it goes without saying that the present invention is not limited to the embodiment and various modifications are possible without departing from the spirit of the present invention. The present invention also includes configurations in which the components of the above-described embodiments are appropriately combined. Such modifications without departing from the spirit of the present invention are also included in the technical scope of the present invention, and this will be clear to those skilled in the art from the claims.

[0081] 1 Water pump (motor), 2s1 First space (space), 3 Shaft, 4 Stator, 5 Rotor, 6 Impeller, 7 Cylinder, 7G1 First groove (groove), 7G2 Second groove (groove), 71 One end, 72 Other end, D1 Depth of first groove, D2 Depth of second groove, X Rotation axis direction, W1 Width of first groove, W2 Width of second groove

Claims

1. A motor comprising: a shaft; a cylinder rotatably supported on the shaft; an impeller fixed to the cylinder; a rotor fixed to the impeller; a stator surrounding the rotor; and a space between the shaft and the cylinder, wherein the cylinder has one end and the other end in the direction of the rotation axis, and one or more grooves extending in the direction of the rotation axis of the cylinder are formed on the inner surface of the cylinder, and the grooves extend continuously from one end to the other end of the cylinder.

2. The motor described in claim 1, wherein the inner surface of the cylinder facing the shaft is provided with two grooves extending circumferentially and a groove extending in the direction of the rotation axis crossing the two grooves, one of the two grooves being formed at one end of the cylinder and the other of the two grooves being formed at the other end of the cylinder.

3. The motor of claim 1, wherein the space contains a liquid.

4. The motor according to claim 3, wherein something other than the liquid passes through the groove extending in the direction of the rotation axis.

5. The motor according to any one of claims 2 to 4, wherein the width of the groove extending in the direction of the rotation axis is larger than the width of the groove extending in the circumferential direction.

6. The motor according to any one of claims 2 to 4, wherein the depth of the groove extending in the direction of the rotation axis is greater than the width of the groove extending in the circumferential direction.

7. The motor according to claim 3, wherein the groove connects a second space formed between the rotor and a bottom wall of a case in which the rotor is housed, to a first space into which the liquid is sucked from the suction port.

Images