Abstract: A roots pump includes a housing, a rotor chamber, a pair of rotary shafts, and a pair of rotors. The rotor chamber includes a rotor chamber peripheral surface facing a pair of distal end portions of each of the rotors. Each of the pair of the distal end portions includes: a pair of rotor peripheral surfaces facing the rotor chamber peripheral surface with a first radial clearance; and a distal end peripheral surface that is formed between the pair of the rotor peripheral surfaces in the rotational direction and faces the rotor chamber peripheral surface with a second radial clearance greater than the first radial clearance. A width of the rotor chamber peripheral surface facing the distal end peripheral surface in the rotational direction is greater than a sum of a pair of predetermined widths of the rotor chamber peripheral surface facing the pair of the rotor peripheral surfaces.

Abstract: A transmission includes a transmission housing member, a ring portion, a high speed shaft, a third roller, and a third plate bearing, which rotatably supports the third roller. The transmission housing member includes a first supporting surface, which restricts the third roller to a first position, and a second supporting surface, which restricts the third roller to a second position. The third roller is moved within a movement range from the first position to the second position. The movement range includes a specified range in which the third roller is not supported, in a radial direction of the high speed shaft, by the transmission housing member with the third plate bearing in between, but is supported by being held between the ring portion and the high speed shaft.

Abstract: First and second pressure relief passages extend from an oil pan in a branching manner, and merge with each other to form a merging portion. A pressure relief hole is arranged above the merging portion, and a first pressure relief passage is arranged below the merging portion. The minimum cross-sectional area of the second pressure relief passage is smaller than the minimum cross-sectional area of the first pressure relief passage. The second pressure relief passage includes a bent portion formed by bending the second pressure relief passage. The bent portion is configured to perform gas/liquid separation by crushing bubbles. When reaching the merging portion from the bent portion, oil is returned to the oil pan via the first pressure relief passage. When reaching the merging portion from the bent portion, gas is discharged to the outside of the housing via the pressure relief hole.

Abstract: A transmission includes a transmission housing member, a ring portion, a high speed shaft, a third roller, and a third plate bearing, which rotatably supports the third roller. The transmission housing member includes a first supporting surface, which restricts the third roller to a first position, and a second supporting surface, which restricts the third roller to a second position. The third roller is moved within a movement range from the first position to the second position. The movement range includes a specified range in which the third roller is not supported, in a radial direction of the high speed shaft, by the transmission housing member with the third plate bearing in between, but is supported by being held between the ring portion and the high speed shaft.

Abstract: An oil passage of a centrifugal compressor includes a first oil passage that communicates with an oil pan and a speed increaser chamber to supply oil to a speed increaser and the seal. A second oil passage communicates with the speed increaser chamber. A third oil passage extends upward in a gravitational direction from an end of the second oil passage. A fourth oil passage extends in a horizontal direction and causes the oil pan and an end of the third oil passage to communicate with each other. A pressure relief passage that communicates with an outside is arranged in at least one of a portion of the fourth oil passage through which a gas layer passes and a portion of the oil pan in which the gas layer is stored.

Abstract: A centrifugal compressor includes a low-speed shaft, an impeller, a speed increaser, a housing, a separation wall, a shaft insertion hole, a seal member, an oil pan, an oil supply passage, an oil return passage, and a pressure reduction passage. The impeller is integrally rotated with a high-speed shaft. The housing has therein an impeller chamber accommodating the impeller and a speed increaser chamber accommodating the speed increaser. The centrifugal compressor includes a bypass passage having a first end communicating with the speed increaser chamber and a second end communicating with the oil pan.

Abstract: A pressure relief passage includes a first pressure relief passage and a second pressure relief passage. A pressure relief hole is provided in an upper part of the first pressure relief passage in the direction of gravitational force. The second pressure relief passage merges with the first pressure relief passage to form a merging portion. The cross-sectional flow area of a stagnation portion, which is the maximum cross-sectional flow area of the second pressure relief passage, is smaller than the cross-sectional flow area of a connection passage, which is the minimum cross-sectional flow area of the first pressure relief passage.

Abstract: A pressure relief passage includes a first pressure relief passage and a second pressure relief passage. A pressure relief hole is provided in an upper part of the first pressure relief passage in the direction of gravitational force. The second pressure relief passage merges with the first pressure relief passage to form a merging portion. The cross-sectional flow area of a stagnation portion, which is the maximum cross-sectional flow area of the second pressure relief passage, is smaller than the cross-sectional flow area of a connection passage, which is the minimum cross-sectional flow area of the first pressure relief passage.

Abstract: First and second pressure relief passages extend from an oil pan in a branching manner, and merge with each other to form a merging portion. A pressure relief hole is arranged above the merging portion, and a first pressure relief passage is arranged below the merging portion. The minimum cross-sectional area of the second pressure relief passage is smaller than the minimum cross-sectional area of the first pressure relief passage. The second pressure relief passage includes a bent portion formed by bending the second pressure relief passage. The bent portion is configured to perform gas/liquid separation by crushing bubbles. When reaching the merging portion from the bent portion, oil is returned to the oil pan via the first pressure relief passage. When reaching the merging portion from the bent portion, gas is discharged to the outside of the housing via the pressure relief hole.

Abstract: A centrifugal compressor includes a partition wall that is arranged between a ring member and the bottom of a main body in a speed-increaser chamber. The centrifugal compressor further includes an introduction passage that guides oil in a stirring region to a storage region. The stirring region includes a region between the partition wall and the ring member in the speed-increaser chamber. The storage region includes a region between the partition wall and the bottom of the main body in the speed-increaser chamber. The oil that has been stirred by rotation of the ring member collides the inner circumferential surface of a speed increaser housing before flowing toward the partition wall. The oil is then guided to the storage region via the introduction passage. Since the oil stored in the storage region is unlikely to be stirred by rotation of the ring member, only a small amount of oil is stirred by the ring member.

Abstract: A centrifugal compressor includes an electric motor coupled to a low-speed shaft, an impeller, and a speed increaser. The speed increaser includes a ring member, a high-speed shaft, rollers, a speed increaser housing member, a discharge passage, and a partition. The ring member includes a circumferential wall and is rotated when the low-speed shaft rotates. The high-speed shaft is coupled to the impeller. The rollers are located between the circumferential wall and the high-speed shaft. The speed increaser housing member stores oil. The discharge passage discharges oil out of the ring member. The partition is located between the speed increaser housing member and the circumferential wall in the radial direction. Power is transmitted from the low-speed shaft to the high-speed shaft by the ring member and the rollers.

Abstract: A speed increaser includes a high-speed shaft, an annular peripheral wall surrounding the high-speed shaft and rotatable with a rotation of a low-speed shaft, the peripheral wall having an inner peripheral surface and a projection extending inwardly from the inner peripheral surface in a radial direction of the high-speed shaft, and a roller disposed between the high-speed shaft and the peripheral wall and having an outer peripheral surface that is in contact with both the projection and an outer peripheral surface of the high-speed shaft. A centrifugal compressor includes the speed increaser, an electric motor driving to rotate the low-speed shaft, and an impeller mounted to the high-speed shaft.

Abstract: A centrifugal compressor includes a housing, a partition separating an empty space in a housing into a speed increaser chamber and an impeller chamber, an insertion hole provided in the partition to allow insertion of a high-speed shaft, a seal located in the insertion hole to seal a boundary between the partition and the high-speed shaft, and a bearing receptacle located in the partition. The partition includes a communication passage that allows communication between a portion of the insertion hole located closer to the speed increaser chamber than the seal and the bearing receptacle.

Abstract: A centrifugal compressor includes a partition wall that is arranged between a ring member and the bottom of a main body in a speed-increaser chamber. The centrifugal compressor further includes an introduction passage that guides oil in a stirring region to a storage region. The stirring region includes a region between the partition wall and the ring member in the speed-increaser chamber. The storage region includes a region between the partition wall and the bottom of the main body in the speed-increaser chamber. The oil that has been stirred by rotation of the ring member collides the inner circumferential surface of a speed increaser housing before flowing toward the partition wall. The oil is then guided to the storage region via the introduction passage. Since the oil stored in the storage region is unlikely to be stirred by rotation of the ring member, only a small amount of oil is stirred by the ring member.

Abstract: A centrifugal compressor includes a low-speed shaft, an impeller, a speed increaser, a housing, a separation wall, a shaft insertion hole, a seal member, an oil pan, an oil supply passage, an oil return passage, and a pressure reduction passage. The impeller is integrally rotated with a high-speed shaft. The housing has therein an impeller chamber accommodating the impeller and a speed increaser chamber accommodating the speed increaser. The centrifugal compressor includes a bypass passage having a first end communicating with the speed increaser chamber and a second end communicating with the oil pan.

Abstract: A centrifugal compressor includes a housing that accommodates an impeller. The housing includes a motor housing, a speed-increasing gear housing, and a compressor housing. The compressor housing has a suction port through which air is drawn in. The compressor housing includes a cylindrical main body, a cylindrical boss, and a fitting portion having a shape of a truncated cone. The cylindrical boss projects from the main body. The boss includes an injection port for spraying water that is generated through power generation by a fuel cell to air flowing through the suction port toward an impeller chamber.

Abstract: An oil passage of a centrifugal compressor includes a first oil passage that communicates with an oil pan and a speed increaser chamber to supply oil to a speed increaser and the seal. A second oil passage communicates with the speed increaser chamber. A third oil passage extends upward in a gravitational direction from an end of the second oil passage. A fourth oil passage extends in a horizontal direction and causes the oil pan and an end of the third oil passage to communicate with each other. A pressure relief passage that communicates with an outside is arranged in at least one of a portion of the fourth oil passage through which a gas layer passes and a portion of the oil pan in which the gas layer is stored.

Abstract: A speed increaser includes an annular peripheral wall rotatable with a rotation of the low-speed shaft, a high-speed shaft disposed within the peripheral wall and having a rotation axis extending in the same direction as that of the peripheral wall, and three rollers disposed within the peripheral wall and in contact with both the peripheral wall and the high-speed shaft. The three rollers are disposed at different positions along the rotation axis of the high-speed shaft with rotation axes of the three rollers extending in the same direction as the rotation axis of the high-speed shaft, and the rotation axes of the three rollers are spaced in a circumferential direction of the high-speed shaft. The three rollers are disposed so that at least part of contact areas between the high-speed shaft and the rollers is free from overlapping with each other along the rotation axis of the high-speed shaft.

Abstract: A centrifugal compressor is provided with a ring member including a circumferential wall, a high-speed shaft located at an inner side of the circumferential wall, and rollers located between the circumferential wall and the high-speed shaft. Each roller includes a circumferential surface and first and second end surfaces. The circumferential surface of each of the rollers includes a contact surface that contacts a portion in a circumferential surface of the high-speed shaft, a first non-contact surface spaced apart from the circumferential surface of the high-speed shaft, and a second non-contact surface spaced apart from the circumferential surface of the high-speed shaft. The contact surface includes a center position located closer to the first flange than a center position of each of the rollers in an axial direction of the rollers.

Abstract: A centrifugal compressor includes a housing, a partition separating an empty space in a housing into a speed increaser chamber and an impeller chamber, an insertion hole provided in the partition to allow insertion of a high-speed shaft, a seal located in the insertion hole to seal a boundary between the partition and the high-speed shaft, and a bearing receptacle located in the partition. The partition includes a communication passage that allows communication between a portion of the insertion hole located closer to the speed increaser chamber than the seal and the bearing receptacle.