A rolling bearing unit including a seal member includes a support frame having window holes, and a filter, the filter being fixedly joined to the support frame, or the support frame and the filter are formed by integral molding such that the window holes of the support frame are closed by the filter. The support frame has an inner diameter determined such that a passage through which lubricating oil can pass is defined between the support frame and the radially outer surface of the inner race. The filter includes a protruding portion protruding radially inwardly beyond the radially inner surface of the support frame such that the radially inner edge of the protruding portion is in contact with the inner race, or such that the protruding portion surrounds the radially outer surface of the inner race through a gap defined therebetween and smaller than the mesh size of the filter.

An electric motor is provided which is designed to minimize a risk of corrosion or stress corrosion cracking of parts thereof and reduce mechanical vibration or noise. The electric motor includes an output shaft, a bearing which retains the output shaft, a frame, and a biasing member. The biasing member is made of austenite stainless steel and disposed between the bearing and a bottom wall of a bearing housing to elastically press the output shaft in a lengthwise direction thereof for eliminating mechanical noise arising from vibration of a rotor. The frame has a coating formed on an outer surface thereof for avoiding erosion thereof. The coating is not formed at least on a portion of the frame which faces the biasing member in order to induce sacrificial corrosion of the frame, which decelerates the corrosion of the biasing member to eliminate a risk of the stress corrosion cracking thereof.

An electric motor is provided which is designed to minimize a risk of corrosion or stress corrosion cracking of parts thereof and reduce mechanical vibration or noise. The electric motor includes an output shaft, a bearing which retains the output shaft, a frame, and a biasing member. The biasing member is made of austenite stainless steel and disposed between the bearing and a bottom wall of a bearing housing to elastically press the output shaft in a lengthwise direction thereof for eliminating mechanical noise arising from vibration of a rotor. The frame has a coating formed on an outer surface thereof for avoiding erosion thereof. The coating is not formed at least on a portion of the frame which faces the biasing member in order to induce sacrificial corrosion of the frame, which decelerates the corrosion of the biasing member to eliminate a risk of the stress corrosion cracking thereof.

A bearing structure includes a shaft member coupled to a motor, two bearings on the shaft member with a distance therebetween in an axial direction, and a housing rotatable relative to the shaft member by means of the bearings, and an electrically-conductive seal member provided between the shaft member and the housing and abutting on the shaft member and the housing. The bearings include inner and outer rings fitted to an outer peripheral surface of the shaft member and an inner peripheral surface of the housing, respectively. The shaft member, housing, and seal member constitute an oil passage. At least one of an abutment portion where the seal member abuts on the shaft member or an abutment portion where the seal member abuts on the housing has a guide groove that guides oil entering the abutment portion from the oil passage to an external space of the oil passage.

A bearing structure includes a shaft member coupled to a motor, two bearings on the shaft member with a distance therebetween in an axial direction, and a housing rotatable relative to the shaft member by means of the bearings, and an electrically-conductive seal member provided between the shaft member and the housing and abutting on the shaft member and the housing. The bearings include inner and outer rings fitted to an outer peripheral surface of the shaft member and an inner peripheral surface of the housing, respectively. The shaft member, housing, and seal member constitute an oil passage. At least one of an abutment portion where the seal member abuts on the shaft member or an abutment portion where the seal member abuts on the housing has a guide groove that guides oil entering the abutment portion from the oil passage to an external space of the oil passage.

Provided is a magnetic fluid sealed bearing having a stable sealing performance in a gap. The magnetic fluid sealed bearing includes: an inner ring and an outer ring; a plurality of rolling elements disposed between the inner and outer rings; a ring-shaped polar plate mounted on an inner circumferential surface of the outer ring such that a gap is formed between the ring-shaped polar plate and an outer circumferential surface of the inner ring; a ring-shaped magnet attached to the ring-shaped polar plate and magnetized such that magnetic poles thereof point to axial directions, to form magnetic circuits on both an outer ring side and an inner ring side; an inner ring magnetic fluid retained in the magnetic circuit on the inner ring side; and a magnetic field intensity increasing portion for increasing magnetic field intensity of the magnetic circuit on the inner ring side.

A magnetic fluid sealing structure (1) for high-speed rotation for sealing a gap (S) between a shaft member (2) and a housing member (3) disposed around the shaft member (2), which are rotatable, includes: magnetic force generating means (4) which is fixed to the housing member (3) and generates a magnetic force; magnetic pole members (5) disposed on both sides in an axial direction of the magnetic force generating means (4); and a magnetic fluid (7) which is magnetically held between the magnetic pole members (5) and the shaft member (2) by the magnetic force of the magnetic force generating means (4) and seals the gap (S) therebetween, in which the shaft member (2) has a plurality of different material layers concentrically laminated in a radial direction, and an outermost diameter layer (23) of the shaft member (2), which holds the magnetic fluid (7), is made of a magnetic material.

A magnetic fluid sealing structure (1) for high-speed rotation for sealing a gap (S) between a shaft member (2) and a housing member (3) disposed around the shaft member (2), which are rotatable, includes: magnetic force generating means (4) which is fixed to the housing member (3) and generates a magnetic force; magnetic pole members (5) disposed on both sides in an axial direction of the magnetic force generating means (4); and a magnetic fluid (7) which is magnetically held between the magnetic pole members (5) and the shaft member (2) by the magnetic force of the magnetic force generating means (4) and seals the gap (S) therebetween, in which the shaft member (2) has a plurality of different material layers concentrically laminated in a radial direction, and an outermost diameter layer (23) of the shaft member (2), which holds the magnetic fluid (7), is made of a magnetic material.

A rolling bearing includes an outer race, an inner race, rolling elements mounted between the outer race and the inner race, and a seal ring formed with an oil passage hole and covering at least one of the axial end openings of the bearing space of the bearing. A filter is mounted to the seal ring so as to cover the oil passage hole of the seal ring, and is configured to catch foreign matter contained in lubricant oil, and a magnetic member is mounted axially inwardly of, and adjacent to, the filter, and is configured to attract foreign matter to the magnetic member due to the magnetic force of the magnetic member.

A rolling bearing includes an outer race, an inner race, rolling elements mounted between the outer race and the inner race, and a seal ring formed with an oil passage hole and covering at least one of the axial end openings of the bearing space of the bearing. A filter is mounted to the seal ring so as to cover the oil passage hole of the seal ring, and is configured to catch foreign matter contained in lubricant oil, and a magnetic member is mounted axially inwardly of, and adjacent to, the filter, and is configured to attract foreign matter to the magnetic member due to the magnetic force of the magnetic member.