A fan device includes a motor and a control unit. The motor has a variable number of revolutions. The motor includes a shaft supported by a bearing enclosing lubricant. The control unit drives the motor. The control unit executes, when continuously driving the motor at a first number of revolutions or less for a first time period, driving the motor at a second number of revolutions more than the first number of revolutions for a second time period shorter than the first time period. The first number of revolutions causes poor oil film formation of the lubricant in the bearing if the motor is driven for more than the first time period. The second number of revolutions causes oil film formation of the lubricant in the bearing if the motor is driven for the second time period.

A heat dissipation device including frame, fan rotating assembly, stator assembly, decorative plate and at least two magnetic components. Frame includes base and barrel connected to base. Fan rotating assembly includes hub and a plurality of blades connected to hub. Fan rotating assembly is rotatably disposed on frame via first bearing fan rotating assembly. Stator assembly is disposed on barrel. Hub covers stator assembly. Decorative plate has decorative design and central pillar connected to decorative plate and extending from decorative plate. Central pillar is connected to hub via second bearing. At least two magnetic components are respectively disposed on decorative plate and stator assembly. One of the at least two magnetic components disposed on decorative plate and another one of the at least two magnetic components disposed on stator assembly are attracted to each other so that decorative plate is stationary while fan rotating assembly rotates.

A gas dynamic bearing includes a shaft extending along a central axis extending vertically, and a sleeve with a hole opening at least at one end of the sleeve in an axial direction, at least a portion of the shaft housed inside the hole. The sleeve includes dynamic pressure grooves in an inner peripheral surface of the hole. The shaft includes a core portion, and a protective portion that is disposed on an outer peripheral surface of the core portion and that includes at least a portion facing the inner peripheral surface of the hole in a radial direction. The protective portion includes a first protective portion and a second protective portion. The first protective portion is at least above or below the second protective portion in the axial direction, and includes at least a portion with a thickness in the radial direction more than a thickness of the second protective portion in the radial direction.

An electric supercharger includes a housing, a rotary shaft rotatably supported in the housing via a rolling bearing, an impeller, and an electric motor. The electric motor including a cylindrical stator around which a coil is wound. The stator having a stator core and coil ends. The rolling bearing has an inner ring, an outer ring, and a rolling element. The housing has an oil supply portion. The oil supply portion has attached thereto an oil supply member. The oil supply member has a supply passage and an injection hole. The housing has therethrough oil supply holes communicating with the oil supply portion and disposed so as to overlap with the coil ends.

A power transmission device includes: a high speed magnet rotor which includes a magnet array which is magnetized in a radial direction; a low speed magnet rotor which includes a magnet array which is magnetized in a circumferential direction; and an inductor rotor which allows magnetic fluxes from the magnet array of the high speed magnet rotor to pass, and the high speed magnet rotor, the low speed magnet rotor and the inductor rotor are concentrically arranged and the magnet array of the low speed magnet rotor is formed such that homopolar surfaces of neighboring magnets face each other in the circumferential direction.

A power transmission device includes: a high speed magnet rotor which includes a magnet array which is magnetized in a radial direction; a low speed magnet rotor which includes a magnet array which is magnetized in a circumferential direction; and an inductor rotor which allows magnetic fluxes from the magnet array of the high speed magnet rotor to pass, and the high speed magnet rotor, the low speed magnet rotor and the inductor rotor are concentrically arranged and the magnet array of the low speed magnet rotor is formed such that homopolar surfaces of neighboring magnets face each other in the circumferential direction.

Two hybrid ball bearings and a compressor bearing arrangement with two hybrid ball bearings for a rotatable support of a rotor of the compressor versus a stator of the compressor. The two hybrid ball bearings are arranged face-to-face or back-to-back, are configured with an optimal axial clearance depending on the inner diameter of a ring-shaped inner raceway element one of the hybrid ball bearings respectively a pitch diameter of one of the two hybrid ball bearings for a long bearing life in connection with an optimal compressor operating performance.

A product may include a bearing housing in which a shaft may be supported by a bearing so that it may rotate. A compressor wheel may be disposed on the shaft. A compressor cover may be connected with the bearing housing, which may form a compressor body and may define a chamber within which the compressor wheel may rotate. A diffuser may extend radially outward from the chamber and may receive gas from the compressor wheel. An inlet may be provided to the compressor body, which may receive a supply of exhaust gas. An EGR distribution cavity may be defined within the compressor body and may extend around the shaft. An EGR inlet channel may extend into the bearing housing from the inlet to the EGR distribution cavity. An EGR passage may extend from the EGR distribution cavity to the diffuser.

A compressor including a motor having a rotary shaft, a rotor and a stator, and an impeller at a front end of the rotary shaft to suction refrigerant in an axial direction and compress the refrigerant in a centrifugal direction. The compressor has a collar at a rear end of the rotary shaft and coupled to the rotary shaft to be extended outwardly in a radial direction of the rotary shaft. Radial bearings support a radial movement of the rotary shaft at a front and rear of the stator. A thrust bearing prevents an axial movement of the rotary shaft. A mechanical backup bearing also prevents the axial movement of the rotary shaft. A fixing unit supports the backup bearing at the rear end of the rotary shaft, wherein the backup bearing is arranged to overlap the thrust bearing in the radial direction of the rotary shaft.

A compressor including a motor having a rotary shaft, a rotor and a stator, and an impeller at a front end of the rotary shaft to suction refrigerant in an axial direction and compress the refrigerant in a centrifugal direction. The compressor has a collar at a rear end of the rotary shaft and coupled to the rotary shaft to be extended outwardly in a radial direction of the rotary shaft. Radial bearings support a radial movement of the rotary shaft at a front and rear of the stator. A thrust bearing prevents an axial movement of the rotary shaft. A mechanical backup bearing also prevents the axial movement of the rotary shaft. A fixing unit supports the backup bearing at the rear end of the rotary shaft, wherein the backup bearing is arranged to overlap the thrust bearing in the radial direction of the rotary shaft.