Abstract: A heat dissipation apparatus. A fan frame includes an air inlet, an air outlet, a passage, and a curved expansion portion. The air inlet is opposite the air outlet. The passage is between the air inlet and the air outlet, guiding airflow from the air inlet to the air outlet. The curved expansion portion is radially and outwardly extended from an inner peripheral wall of the passage at the air inlet or air outlet. An impeller is disposed in the fan frame and includes a plurality of blades. Each blade is disposed in the passage and includes an extension end extending to the curved expansion portion.

Abstract: A mounting structure for a motor includes a tube and a stator. The tube includes at least an axial positioning block and at least a radial mounting block. The stator defines an axis hole for receiving a portion of the tube therein, and at least a positioning groove in an inner surface thereof. One of the stator and the tube is rotated from an unlock position, where the at least an axial positioning block is located just above the at least a positioning groove, to a locked position, where a bottom surface of the at least an axial positioning block abuts a top surface of the stator and the at least a radial mounting block engages with the inner surface of the stator.

Abstract: A heat-dissipating device and a housing thereof. The housing includes a passage for guiding an air stream flowing from an opening to another opening, wherein an sidewall of the passage at least one of the opening sides extends radially outwards with a rotational axis of the heat-dissipating device or the passage so as to enlarge intake or discharge area for the air streams. Accordingly, the intake airflow rate may be greatly increased and the heat-dissipating efficiency of the heat-dissipating device may be greatly enhanced without changing assembling conditions with other elements.

Abstract: Fan apparatus for an air conditioner including a fan (50), a shaft (68) coupled to the fan (50), a rotor (60) for transmission of driving force to the shaft (68) for rotating the fan (50), a stator (65) on an inside of the rotor (60) to form a BLDC motor together with the rotor (60), and a fan housing (40) for enclosing the fan (50), thereby reducing noise and enhancing fan (50) efficiency.

Abstract: A brushless fan motor, in which cooling effect on a stator may be enhanced, is provided. A center through hole is formed in a center of a bottom wall portion of a first brushless fan motor. Vane portions are formed on an inner wall portion of the brushless fan motor and are formed into a shape which allows ambient air to be drawn in through the center through hole. Through holes are formed in an end plate portion of the first brushless fan motor in order to introduce the ambient air, which has been drawn in through the center through hole, inside a rotor cover.

Abstract: A fan apparatus includes an impeller, a motor rotating the impeller, a plurality of stator blades arranged opposite to the impeller in an axial direction. The stator blades each include a curved portion at which the stator blades each are curved with respect to the direction in which the stator blades extend.

Abstract: A vortex pump comprises: an impeller that includes a plurality of blades at an outer circumference and a rotor magnet placed at an inner circumference; a shaft fixed at a center of the impeller; a bearing component placed at an outer circumference of the shaft; a motor stator placed at an inner circumference side of the rotor magnet; and a case structural component having a suction port and a discharge port that functions to house the impeller and furthermore to divide the impeller and the motor stator. A motor stator side surface of the case structural component is covered with an adhesive material to cause the motor stator to adhere to the motor stator side surface.

Abstract: A heat dissipation fan includes a rotor (1) having a hub (10) with a permanent magnet (104) attached to an inner surface thereof, a stator (2) and a fan frame (3) having a bearing seat (36). The bearing seat (36) includes a base (361) and a central tube (362) around which the stator is mounted. Slots (102) are defined through the top wall of the hub facing to the magnet ring. The base defines slots (360), corresponding to the slots of the hub.

Abstract: A motor includes a rotor and a stator. The stator includes a circuit board on which a control circuit for controlling rotation of the rotor is formed. A circuit component of the control circuit is mounted on a surface of the circuit board facing a base portion. A heat conductive member is arranged between the base portion and the circuit component to be in contact with the base portion and the circuit component. Thus, a heat generated by the circuit component is transferred to the base portion through the heat conductive member and is then transferred to connecting portions and a wall of a housing which are formed integrally with the base portion from thermally conductive material.

Abstract: An axial fan motor comprising: a fan having a rotating shaft and composed of a hub and a plurality of vanes provided around the hub, the fan rotating to generate an air flow; a stator substrate set comprising a stator core, which drives the fan, an insulator, and a substrate; and a venturi having a sleeve, into an inner peripheral side of which a bearing is inserted to support the rotating shaft and to an outer peripheral side of which the stator core is fixed, the venturi being formed on one side thereof with an air suction opening and on the other side thereof with an air discharge mouth, wherein a space is provided between the stator core and the sleeve.

Abstract: A single-phase motor comprising a rotor magnet, a stator core having salient poles, and a coil wound around the stator core, a rising portion and a falling portion of a voltage applied to the coil have different inclinations, wherein the salient pole is separated into three angle portions, a radius of an outer shape of the salient pole is reduced little by little with respect to a rotating direction of the rotor in a first angle portion with respect to the rotating direction of the rotor, is increased little by little with respect to the rotating direction of the rotor in a second angle portion with respect to the rotating direction of the rotor, and is increased little by little with respect to the rotating direction of the rotor in a third angle portion with respect to the rotating direction of the rotor, and a rate of increase of the third angle portion is gentler than that of the second angle portion.

Abstract: An impeller, which is driven by a stator, includes a conducting shell, a hub and a plurality of blades. The conducting shell covers at least one side of the stator. The hub covers the conducting shell. At least one air gap is formed between the hub and the stator. A top portion of the hub has an opening to partially expose a top portion of the conducting shell. At least one airflow passage is formed between an inner wall of the hub and an outer surface of the conducting shell. The airflow passage has at least one inlet connected with the opening and at least one outlet connected with the air gap. The blades are disposed around the circumferences of the hub.

Abstract: A fan includes a shaft, a hollow, approximately cylindrical rotor yoke that rotates around the shaft as a rotation axis and is open toward one of its axial ends, a rotor magnet secured to an inner circumference of the rotor yoke, and an impeller secured to an outer circumference of the rotor yoke and arranged to rotate together with the rotor yoke to generate an air flow. One of the impeller and the rotor yoke is provided with an index used for circumferentially positioning the impeller or the rotor yoke.

Abstract: An arrangement of a low air inlet and a circuit for driving a torque generator in an ultra-compact centrifugal fan is disclosed. In the ultra-compact centrifugal fan, a region occupied by the circuit is not completely arranged radially inside a cup-shaped portion to which an impeller is attached. At least a part of the low air inlet provided on a bottom of a housing of the centrifugal fan is arranged in a range of predetermined angle in an imaginary ring-shaped portion surrounding a base portion covered by the cup-shaped portion. A part of the circuit, that is not covered by the cup-shaped portion, is arranged upstream of the range of the predetermined angle in a flowing direction of airflow.

Abstract: A ring-shaped member is secured to a shaft of a motor between a portion of the shaft connected to a rotor and a sleeve accommodating the shaft and impregnated with lubricating oil. The ring-shaped member is coated with a repellent agent repelling the lubricating oil. An outer diameter of the ring-shaped member at its sleeve side, i.e., a first outer diameter is larger than that at the opposite side, i.e., a second outer diameter. A shaft-retaining portion is provided between the connected portion of the shaft and the ring-shaped member. A diameter of the hole is larger than the first outer diameter and smaller than the second outer diameter. At least one of the ring-shaped member and the shaft-retaining portion is elastically deformable.

Abstract: An easy-to-assemble electric motor (21) features an internal stator (50), an external rotor (22) having a shaft (34), which external rotor is configured as a rotor cup or bell (24) having an outer side and an inner side (25), a bearing tube (70) for receiving a bearing arrangement (60) journaling the shaft (34), which bearing tube (70) has a first end portion (71) facing toward the inner side (25) of the external rotor (22) and being formed with an inwardly protruding stop (73), the bearing tube having a second end portion (75) facing away from the first end portion (71) and being joined to a plastic part (80) that likewise forms an inwardly protruding stop (77) adjacent a second end portion (75), the bearing arrangement (60) being located in the bearing tube (70) in a chamber defined between said two inwardly protruding stops (73, 77).

Abstract: An electric pump may comprise a pump case (110, 150) having a pump chamber. An impeller 143 may be rotatably disposed within the pump chamber. The impeller 143 may include a magnetized cylindrical portion 145. A stator 133 may be disposed opposite to the cylindrical portion 145 of the impeller 143. The stator 133 may drive the impeller 143 by applying magnetic forces to the cylindrical portion 145 of the impeller 143. A shaft 146 may be formed integrally with the impeller 143. One end of the shaft 143 may be rotatably supported with respect to the pump case.

Abstract: A motor assembly comprises a plurality of redundant bearings, a plurality of coaxial support elements, with at least one of the support elements rotatable about an axis of rotation, and an armature rotatably guided by the plurality of support elements to rotate about the axis of rotation. The bearings provide redundancy to continue armature rotation in the event one bearing fails.

Abstract: A motor rotor. The motor rotor adapted to be used in a fan includes a hub, a metal plate and a magnet. The metal plate has a first end and a second end. The metal plate is disposed in the hub. The magnet is disposed in the metal plate. A method for manufacturing a motor rotor mentioned includes providing a metal plate having a first end and a second end; connecting the first and second ends to shape the metal plate as a ring; placing the metal plate in a hub; and placing a magnet in the metal plate.

Abstract: A heat-dissipating device and a housing thereof. The housing includes a passage for guiding an air stream flowing from an opening to another opening, wherein an inner wall of the passage at at least one of the opening sides extends radially outwards with a rotational axis of the heat-dissipating device or the passage so as to enlarge intake or discharge area for the air streams. Accordingly, the intake airflow rate may be greatly increased and the heat-dissipating efficiency of the heat-dissipating device may be greatly enhanced without changing assembling conditions with other elements.

Abstract: A fluid moving device with a heat radiation, which is mounted to a conductive part to dissipate heat from a heat generation part under the fluid moving device and another heat generation part around the first heat generation part, includes a first frame member, which has an area thereof being equal to that of the conductive part and a base member being movably attached with the fan wheel, and a second frame member, which has a second hollow part with an area thereof being greater than the first frame member and provides a projection section extending beyond four sides of the first frame member. Once the fan wheel rotates, the fluid is dragged to enter the fluid moving device via the second hollow part and to leave via the first hollow part so as to dissipate heat in and around the conductive part.

Abstract: A heat-dissipating fan of the invention has an axle, a bearing, a rotor and a stator. The axle and the bearing are made of a ceramic material, and are located at a central location of the rotor and the stator. The bearing is a hollow cylinder integrally formed into a single body, and has a central hole and a recess at its bottom. The axle penetrates through the central hole of the bearing to contact the recess. A magnetic force center of the silicon steel sheet is at a level lower than that of the magnetic bar to generate radial and axial force components, allowing stable rotation of the rotor. The heat-dissipating fan of the invention provides advantages such as low friction, lower noise, low energy consumption, high performance and high stability.

Abstract: A hub assembly includes an axle having one end mounted fittingly in a metal socket member. A hub body includes a cylindrical wall formed integrally with a base wall and extending uprightly from an inner surface of the base wall, and a coupling tube formed integrally on the inner surface of the base wall. The cylindrical wall has a central axis transverse to the base wall. The coupling tube extends along the central axis, and has the socket member fixed therein.

Abstract: An axial flow fan motor having an impeller molded integrally with a shaft from a synthetic resin. The shaft is easily assembled with a bearing arrangement by being brought into tight contact with the inner ring of the bearing arrangement and is reliably fixed thereto in the elastic region of the shaft. A through hole is formed in the shaft along its central axis. After the shaft is fit into the inner ring of the bearing arrangement, a metal pin is pressed into the axial through hole. Because the pin is pressed in, the shaft is elastically expanded and brought into tight contact with the inner ring and fixed thereto in the elastic region of the shaft. Furthermore, the distal end portion of the shaft elastically outwardly expands and is pressed against the end surface of the inner ring, thereby preventing the bearing arrangement from coming off the shaft.

Abstract: A cooling fluid pump in which a cooling fluid is caused to flow to cool a heating element includes a casing brought into a direct contact or an indirect contact via a heat transfer member with the heating element, a pump chamber defined in the casing, an impeller rotatably mounted in the pump chamber and including a pump groove formed in either one of both axial end faces, the impeller having an axis of rotation located radially away from a center of the casing, an inlet formed in the casing so that the cooling fluid is supplied through the inlet into the pump chamber by an action of the pump groove with rotation of the impeller, and an outlet formed in the casing so that the cooling fluid is discharged through the outlet out of the pump chamber by an action of the pump groove with rotation of the impeller.

Abstract: An axial-flow fan has a plurality of main fins (702), and auxiliary fins (703) provided between the main fins (702), where the position of a front end of the auxiliary fin (703) relative to X axis and the position of a front end of the main fin (702) adjoining the auxiliary fin in reverse-rotary direction are aligned, the height of the auxiliary fin (703) is approximately three fourths of the height of the main fin (702), and the cross sections of the main fin (702) and the auxiliary fin (703) taken along the axial direction of the main shaft are streamlined.

Abstract: A rotor assembly includes a housing and a hub. The housing has an open end and an opposed closed end, and is formed with a raised portion in the central location of the closed end. The hub is mounted on the closed end of the housing and covers the housing except for the raised portion to construct a thin motor.

Abstract: A tubeaxial fan (10) broadly including a cylinder (12), a propeller (14) rotatably supported in the cylinder (12), and a drive assembly (16) operable to rotate the propeller (14) is disclosed. The propeller (14) includes blades (28,30,32,34,36,38) each having an inventive blade design. The inventive blade design presents a chord length (C), a stagger angle (?e), and a camber height (?c) that vary along each of the blades as shown in TABLE 1. The inventive blade design presents an external surface of each of the blades having a shape defined by the relative positioning of a plurality of coordinates contained in at least nine cross-sections (e.g., the blade (28) includes cross-sections (44,46,48,50,52,54,56,58,60)). The cross-sections (44,46,48,50,52,54,56,58,60) of the illustrated blade (28) have the corresponding plurality of coordinates listed in TABLE 2.

Abstract: A fan with increased air flow having a casing in which an air passage hole is formed. A motor is connected to this casing and is held in the center of the air passage hole by a motor base positioned within the air passage hole. Multiple blades are rotated by the motor and covey air from the air passage hole intake port side to the exhaust port side. The annular outer wall of the fan is inclined with respect to the center axis towards the air passage hole exhaust port. By this means, a fan is capable of attaining a greater airflow volume than conventional fans, while having the same outward shape as a conventional fan.

Abstract: A hub of a fan wheel with improved attachment for a metal case. The fan wheel is composed of a hub with a storage portion and a plurality of blades arranged around circumference of the hub. A metal case with a magnetic part is disposed in the storage portion of the hub. A plurality of blocking chunks is disposed in the end side of the storage portion of the hub, and at least one hook is disposed at proper position in the end side of the storage portion of the hub. A plurality of ribs is disposed inside the storage portion of the hub. The metal case has a penetrated hole with a stopper in one end of the penetrated hole. A recess is set between the stopper and the magnetic part.

Abstract: The object of the present invention is to provide a blower in which electrical components such as printed circuit board or electronic parts are isolated from the wind flowing through the blower to protect these components from moisture, dirt, dusts, or other harmful gas or substance contained in the wind, and to prevent the degradation of the insulating property such as the electric insulation or dielectric strength.

Abstract: An improved structure for rotational support for a heat-dissipation fan is disclosed, comprising a hollow ceramic bearing passing through and concentric with the fan rotor and rotating with said rotor, a hollow ceramic support bearing fixedly mounted to the base of the fan, and a hollow or solid ceramic axle tube passing through the inside of said bearing and rotating freely to reduce friction and allow high-speed rotation. The exterior surface of said bearing is ground or otherwise formed to provide better connection with the rotor, while the interior of the bearing and exterior of the axle tube are further processed to reduce contact area therebetween to reduce rotation friction. This improved structure has achieved reduced friction, reduced noise, reduced power consumption, longer life and higher rotational speed.

Abstract: An external rotor brushless DC motor for use in a fan, or other similar application, the motor including a stator assembly base having a base plate, a number of stator windings affixed to the stator base, and circuitry associated with the motor, wherein the base plate is disposed between the circuitry and the stator windings.

Abstract: A fan motor structure includes a fan base, a bearing assembly, a fan hub and a shaft. The fan hub is formed with an extrusion protruding from its top planar surface, and the shaft is fit into the bearing assembly and connected to the fan hub. The shaft has one end protruding from the top planar surface of the fan hub to form an extension portion, and the extension portion of the shaft is enclosed by and in close connection with the extrusion of the fan hub.

Abstract: To attain the cost saving, the integration of an impeller and a motor yoke of an outer rotor type motor drive blower can be performed in a one-touch manner in a working process for fixedly attaching the motor yoke within the impeller. The motor yoke 6a is formed to have a cylindrical portion. Also, the impeller 5 is integrally formed of elastic synthetic resin with a cylindrical portion 5a within which the motor yoke 6a can be fixedly attached and fans 5b around the cylindrical portion with hooking members (bosses) 12 for the motor yoke 6a. Then, the motor yoke 6a and the impeller 5 are integrally formed with each other by engaging the elastic hooking members 12 with the motor yoke 6a when the motor yoke 6a is fixedly attached within the cylindrical portion 5a of the impeller 5.

Abstract: A fan in which, on one end of the motor shaft 6 a stepped portion 19 having a small diameter is formed, on which a central portion of the motor yoke 11 is press-fitted and fixed by caulking, thereby the motor yoke is mounted directly on the shaft 6. By such a structure, the conventional boss between the shaft 6 and the motor yoke 11 can be omitted and the structure can be simplified.

Abstract: A fan with improved self-cooling capability having a frame, a stator, a magnetic ring, an iron case, and a rotor blade impeller. The frame has a base for containing the stator, and the stator is provided with at least a coil. The magnetic ring is magnetically coupled to the stator, and the iron case is coupled to the magnetic ring while being provided with at least a first heat dissipation hole. The rotor blade impeller is formed on the iron case, in which at least a second heat dissipation hole aligned to the first heat dissipation hole is formed on a hub of the rotor blade impeller, and the first heat dissipation hole and the second heat dissipation hole are not formed to directly align to a position of the coil.

Abstract: An apparatus to render the shield of a bail bearing unnecessary and to improve the lubricity inside a fan motor is presented. A bearing housing is integrally formed with a base of the fan motor, and a shield part is formed at one end of the bearing housing. A ball bearing, spacer and sleeve bearing are set inside from the other end of the bearing housing, and these are fixed in place by pressing in a retainer cap. The interior of the bearing housing is then shielded at each end by the shield part and the retainer cap, making the need for a shielded ball bearing unnecessary. A rotational shaft, to which a rotor and impeller are attached, is supported by the ball bearing and the sleeve bearing. Inside the bearing housing, lubricating oil passes back and forth between the ball bearing and sleeve bearing, thereby enabling the elimination of insufficiencies in lubricating oil, and improving lubricity.

Abstract: A cooling fan structure comprises a base and a ring stator mounted in the center of the base such that a plurality of polar claws are bent to form in the inner side of the ring stator in conjunction with a plastic material. A coil is wound in the outer side of the ring stator. A blade rotor seat is mounted in the base such that the blade rotor seat circumvents the ring stator. A magnetic ring rotor is mounted on an axis in the receiving space of the ring stator such that the magnetic ring rotor is induced by the coil of the ring stator to drive the blades.

Abstract: A mini fan mounting arrangement in which the stator has an annular locating flange at the center of the top insulation frame thereof, and the fan blade assembly has a plurality of springy hooks equiangularly spaced around the center shaft thereof and respectively hooked in the annular locating flange to secure the fan blade assembly to the stator for enabling the fan blade assembly to be rotated on the stator.

Abstract: A fan (1) includes a housing (20), a vane assembly (40), and a sealing device (70). The housing includes a base portion (22), a bearing sleeve (24), a self-lubricating bearing (26) received in the bearing sleeve, and a lubricant insulation ring (28) received in the bearing sleeve. The vane assembly is rotatably attached in the housing, with a central rod (44) of the vane assembly extending through the bearing and the lubricant insulation ring. The sealing device is attached to the base portion such that the bearing is sealed in the bearing sleeve between the lubricant insulation ring and the sealing device. A sealing ring (80) of the sealing device is disposed in an annular groove (39) defined in the base portion, and is pressed tightly between the sealing lid and the base portion.

Abstract: A fan assembly includes a mounting tube having an annular flange extending radially and inwardly from an inner wall surface thereof. A rotor includes a rotor shaft extending into the mounting tube. First and second bearings are sleeved on the rotor shaft, and each has an abutment plate, and a peripheral flange that extends axially from the abutment plate, that slidably contacts the inner wall surface of the mounting tube, and that cooperates with the rotor shaft and the abutment plate to define a lubricant-receiving reservoir thereamong. Two annular bearing-covering caps are sleeved on the rotor shaft to sealingly cover the lubricant-receiving reservoirs in the first and second bearings.

Abstract: A ceiling fan has a stator 38 rigidly mounted to a shaft 33 and a rotor 40 rotatably mounted to the same shaft about the stator. The shaft is rigidly mounted to a housing. The rotor is supported upon a thrust bearing.

Abstract: A cooling fan dust structure has provided on the end of the fan blade hood a recess that mutually forms an overcut height difference with a flange protruding from the peripheral of a motor base so to prevent the airflow carrying dust an easy ingression and even keep off the flying dust from entering into the spindle as the fan blade unit rotates.

Abstract: An electrical fan comprising a blade module and a coil module. The blade module includes a space defined therein, and a shaft. The space has a bottom where an end portion of the shaft is embedded. The coil module includes an oil-retaining bearing, an oil-retaining ring, and a shaft sleeve. The shaft sleeve has an internal flange at a top thereof. The oil-retaining bearing is mounted inside the shaft sleeve, and the oil-retaining ring is clamped between the internal flange and the oil-retaining bearing once the shaft of the blade module has penetrated through the shaft sleeve and the oil-retaining ring of the coil module. Via the oil-retaining ring, the lubricant oil is retained in the oil-retaining bearing, thereby preventing loss and evaporation of lubricant oil.

Abstract: An improved structure of rotation support of heat-dissipation fan comprising ceramic hollow tube bearing passes through and fixes on fan rotor and rotating with rotor, hollow or solid ceramic axle tube passes through the inside of bearing and rotating freely or fixed to fan body to provide low friction and high speed rotation. Exterior surface of bearing is formed or ground to provide better connection with rotor body while interior of bearing and exterior of axle tube are further processed to reduce surface contact area thereof lower rotational friction. This improved structure has achieved lower friction, lower noise, lower power consumption, longer life and higher speed.

Abstract: An improved fan comprises a blade module and a coil module. The blade module includes a space defined therein, and a shaft. The space has a bottom where an end portion of the shaft is embedded. The coil module includes an oil-retaining bearing, an oil-retaining ring, and a shaft sleeve. The shaft sleeve has an internal flange at a top thereof. The oil-retaining bearing is mounted inside the shaft sleeve, and the oil-retaining ring is clamped between the internal flange and the oil-retaining bearing once the shaft of the blade module has penetrated through the shaft sleeve and the oil-retaining ring of the coil module. Via the oil-retaining ring, the lubricant oil is retained in the oil-retaining bearing, thereby preventing loss and evaporation of lubricant oil.

Abstract: A heat dissipation fan includes a fan blade body having a shaft mounted thereon; an inner assembly installed within the fan blade body, the inner assembly comprises an iron casing, a ring-shaped permanent magnet installed inside the iron casing, a stator bobbin with the winding of a coil thereof, and a sleeve installed in the center of the stator bobbin, and within the sleeve there are mounted a ball bearing and a lubricating bearing under the ball bearing, and wherein an upper end of the ball bearing abuts against an O-ring and a lower end of the lubricating bearing abuts against a C-type clamping ring, and wherein a lower end of the sleeve is securely mounted on a circuit board and a base; and a magnetic device installed on the base in a position corresponding to a lower end of the shaft to attract the shaft.

Abstract: A cooling fan has a housing. A stator is securely mounted in the housing and has a coil, an upper pole sheet and a lower pole sheet coaxially provided at a top and a bottom of the coil respectively. A circuit board is provided beneath the lower pole sheet. An oil-retaining bearing is mounted in the stator. A rotator is received in the housing and has a cap covering the stator. A spindle is formed at the center of the cap and inserted through the oil-retaining bearing. A dustproof disk is provided between the circuit board and the lower pole sheet and is received in the cap of the rotator. A gap between the circuit board and the cap is sealed by the dustproof disk, and dust will not enter into the rotator to block the oil-retaining bearing.

Abstract: A centrifugal fan capable of exhibiting enhanced waterproof performance without using a resin mold while being simplified in structure. Air is sucked from one axial side of a revolving shaft of an electric motor and discharged in a radial direction of the revolving shaft. A second side wall of a casing and a wall of a blade support of an impeller have opposite surface portions arranged opposite to each other in an axial direction of the revolving shaft, respectively. The opposite surface portions are formed into a configuration which permits the opposite surface portions to cooperate with each other to provide a labyrinth structure for preventing water from intruding into a space defined between a cup-like member and the second wall from an outside in the radial direction of the revolving shaft. A first side wall and the second side wall are formed with drainage through-holes.