In a scroll compressor, a first flow passage is formed in a fixed base plate and a frame to supply oil separated by an oil separating mechanism provided in a sealed container to an oil sump at the bottom of the sealed container. In the fixed base plate, a second flow passage is formed to supply the oil separated by the oil separating mechanism into a compression mechanism.

A fluid delivery device having a forepump and a main pump fluidically connected to the forepump, wherein the forepump can be driven via a forepump input shaft and the main pump can be driven via a main pump input shaft. According to the invention, the forepump has a forepump drive gear coupled to the forepump input shaft and a forepump delivery gear interacting with the forepump drive gear to deliver the fluid, wherein the forepump and the main pump are drivingly coupled to a common drive shaft, and wherein the forepump delivery gear and the main pump input shaft are connected to one another via a connecting shaft such that the forepump input shaft is coupled directly to the drive shaft and the main pump input shaft is coupled to the drive shaft via the connecting shaft.

A fluid delivery device having a forepump and a main pump fluidically connected to the forepump, wherein the forepump can be driven via a forepump input shaft and the main pump can be driven via a main pump input shaft. According to the invention, the forepump has a forepump drive gear coupled to the forepump input shaft and a forepump delivery gear interacting with the forepump drive gear to deliver the fluid, wherein the forepump and the main pump are drivingly coupled to a common drive shaft, and wherein the forepump delivery gear and the main pump input shaft are connected to one another via a connecting shaft such that the forepump input shaft is coupled directly to the drive shaft and the main pump input shaft is coupled to the drive shaft via the connecting shaft.

A pump device 1 includes a relief valve 42 having a ball 45 and a valve seat 44. The valve seat 44 has a ring-shaped seat surface 52 having a wide portion 52a and a narrow portion 52b on which the ball 45 is seated. Upon valve opening, the ball 45 is pressed in a valve opening direction by a pressing force F1 according to a pressure P of working fluid while being pressed against the wide portion 52a. The ball 45 rolls on the seat surface 52 upon the valve opening while continuing or keeping contact with the wide portion 52a. At this time, the ball 45 is stably held with the ball 45 contacting the wide portion 52a of the seat surface 52. Noise of the relief valve 42 caused by vibration of the ball 45 is therefore suppressed.

A pump device 1 includes a relief valve 42 having a ball 45 and a valve seat 44. The valve seat 44 has a ring-shaped seat surface 52 having a wide portion 52a and a narrow portion 52b on which the ball 45 is seated. Upon valve opening, the ball 45 is pressed in a valve opening direction by a pressing force F1 according to a pressure P of working fluid while being pressed against the wide portion 52a. The ball 45 rolls on the seat surface 52 upon the valve opening while continuing or keeping contact with the wide portion 52a. At this time, the ball 45 is stably held with the ball 45 contacting the wide portion 52a of the seat surface 52. Noise of the relief valve 42 caused by vibration of the ball 45 is therefore suppressed.

A screw spindle pump constituted by at least two parts is disclosed. The first part includes a housing and at least one spindle system disposed in the housing and capable of being driven in a rotational manner. Furthermore, a pressure region disposed downstream of the spindle system and at least one outlet opening which is connected to the pressure region, the outlet opening discharging the delivery medium out of the pressure region. The second part includes at least one low-pressure chamber disposed upstream of the spindle system and at least one inlet opening for the delivery medium into the low-pressure chamber. The first part and the second part are coupled together, preferably in a rotational manner, so that they can assume at least two different relative positions.

A pump system includes a triple-gear pump which pressurizes a fluid using three gears; an outlet flow path which guides the fluid from a first pressure-increasing portion to an outlet; a first flow path which guides the fluid from the first pressure-increasing portion to a second pressure-increasing portion; a second flow path which guides the fluid from the second pressure-increasing portion to the outlet flow path; a third flow path connected to the first flow path and the second flow path; a first valve device provided in the first flow path; a second valve device provided in the second flow path, and a control device which controls the first valve device. When the first pressure-increasing portion and the second pressure-increasing portion are switched from a parallel state to a series state, the control device causes the first valve device to open after the second valve device is closed.

A pump system includes a triple-gear pump which pressurizes a fluid using three gears; an outlet flow path which guides the fluid from a first pressure-increasing portion to an outlet; a first flow path which guides the fluid from the first pressure-increasing portion to a second pressure-increasing portion; a second flow path which guides the fluid from the second pressure-increasing portion to the outlet flow path; a third flow path connected to the first flow path and the second flow path; a first valve device provided in the first flow path; a second valve device provided in the second flow path, and a control device which controls the first valve device. When the first pressure-increasing portion and the second pressure-increasing portion are switched from a parallel state to a series state, the control device causes the first valve device to open after the second valve device is closed.

A compressor includes a casing configured to accommodate refrigerant and oil, a discharger disposed at a side of the casing and configured to discharge the refrigerant, a driver including a stator and a rotor, a rotation shaft that is coupled to the rotor and that extends in a direction away from the discharger, a compressing assembly that is coupled to the rotation shaft, that is configured to be lubricated with the oil, and that is configured to compress the refrigerant and discharge the compressed refrigerant in the direction away from the discharger, a muffler coupled to the compressing assembly and configured to guide the refrigerant to the discharger, and a bypassing portion disposed outside the casing and configured to transfer the refrigerant or the oil from the muffler to the discharger.

This disclosure generally relates to an automatic bicycle, particularly to a hydraulic automatic transmission bicycle which can automatically and adaptively change gear ratios. More particularly, this disclosure relates to those hydraulic automatic transmission bicycles which use fluid pressure to change such gear ratios, and which include various hydraulic automatic transmissions which may be provided in various configurations and may operate in various methods and sequences to provide automatic and infinitely variable gear ratios.