Abstract: A fuel cell centrifugal compressor includes: an impeller including a hub and blades; and a shroud. A smaller one of angles formed by each blade and a meridian surface is a blade angle. An absolute value of the blade angle on a hub-side of the blade is local minimum between hub-side front and rear edges of the blade. An absolute value of the blade angle on a shroud-side of the blade is local minimum between shroud-side front and rear edges of the blade. The hub-side of the blade is constantly less than or equal to the shroud-side of the blade in absolute value of the blade angle between the hub-side front and rear edges. The shroud-side rear edge is less than the shroud-side front edge in absolute value of the blade angle. The hub-side rear edge is greater than the hub-side front edge in absolute value of the blade angle.

Abstract: A centrifugal compressor comprises an impeller including a hub and a plurality of blades. Each blade has a positive pressure surface and a negative pressure surface extending from one side of an external radial surface toward the other side of the external radial surface and being of a positive pressure and a negative pressure, respectively, when the impeller rotates. The hub has a lightening hole that opens to the external radial surface between the positive pressure surface and the negative pressure surface of the plurality of blades. The lightening hole is provided closer to the positive pressure surface of the blade than the negative pressure surface of the blade.

Abstract: An electric motor includes a slot insulation member arranged in a slot between adjacent ones of coils in a circumferential direction of a yoke. The slot insulation member is a wedge-shaped spacer and includes a main body and projections. The projections are arranged in the slot and projected from the main body. The coil includes a main coil portion, a coil end, and a bent coil portion. The main coil portion is arranged in the slot and sandwiched between a corresponding one of the projections and a corresponding tooth. The coil end is arranged outside the slot and contacts the main body. The coil end is wider than the main coil portion. The bent coil portion connects the main coil portion and the coil end.

Abstract: A centrifugal compressor comprises an impeller including a hub and a plurality of blades. The hub is provided with a through hole. The hub has an external radial surface having an inner external radial surface and an outer external radial surface. The outer external radial surface is formed closer to a back surface than an imaginary curved surface having as a radius a radius of curvature of the inner external radial surface at a radially outer edge thereof.

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 centrifugal compressor comprises a rotation shaft, an impeller, and a casing. The impeller has a hub and a plurality of blades. The casing has an opposite surface facing a back surface of the hub, and a projection projecting from the opposite surface toward the impeller. The hub is provided with an accommodation space that accommodates the projection. The accommodation space includes a through hole penetrating the hub from the back surface toward an external radial surface. The through hole opens while avoiding the blades.

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: A fuel cell centrifugal compressor includes: an impeller including a hub and blades; and a shroud. A smaller one of angles formed by each blade and a meridian surface is a blade angle. An absolute value of the blade angle on a hub-side of the blade is local minimum between hub-side front and rear edges of the blade. An absolute value of the blade angle on a shroud-side of the blade is local minimum between shroud-side front and rear edges of the blade. The hub-side of the blade is constantly less than or equal to the shroud-side of the blade in absolute value of the blade angle between the hub-side front and rear edges. The shroud-side rear edge is less than the shroud-side front edge in absolute value of the blade angle. The hub-side rear edge is greater than the hub-side front edge in absolute value of the blade angle.

Abstract: A centrifugal compressor comprises an impeller including a hub and a plurality of blades. Each blade has a positive pressure surface and a negative pressure surface extending from one side of an external radial surface toward the other side of the external radial surface and being of a positive pressure and a negative pressure, respectively, when the impeller rotates. The hub has a lightening hole that opens to the external radial surface between the positive pressure surface and the negative pressure surface of the plurality of blades. The lightening hole is provided closer to the positive pressure surface of the blade than the negative pressure surface of the blade.

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 comprises a rotation shaft, an impeller, and a casing. The impeller has a hub and a plurality of blades. The casing has an opposite surface facing a back surface of the hub, and a projection projecting from the opposite surface toward the impeller. The hub is provided with an accommodation space that accommodates the projection. The accommodation space includes a through hole penetrating the hub from the back surface toward an external radial surface. The through hole opens while avoiding the blades.

Abstract: A centrifugal compressor comprises an impeller including a hub and a plurality of blades. The hub is provided with a through hole. The hub has an external radial surface having an inner external radial surface and an outer external radial surface. The outer external radial surface is formed closer to a back surface than an imaginary curved surface having as a radius a radius of curvature of the inner external radial surface at a radially outer edge thereof.

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: 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 motor-driven compressor includes an electric motor, a housing including a tubular bearing holder, and plastic members. Each of the plastic members includes a connecting passage. The electric motor includes a stator including a stator core and coils. The coils include a coil end. The connecting passage has opposite ends in the axial direction, each of the opposite ends including an opening so that two spaces defined by the stator core in the housing are connected to each other through the connecting passage. The bearing holder is at least partially opposed to one of the openings of the connecting passage and disposed at an inner side of the coil end in the radial direction.

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: 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.