Abstract: A vacuum pump includes rotary shafts connected to a pair of screw-type rotors, respectively, and a pair of shaft retainers extending in the housing. Each shaft retainer supports the corresponding rotary shaft by means of a proximal bearing portion and a distal bearing portion. Each pair of the proximal and distal bearing portions are fixed in the axial direction with respect to the corresponding rotary shaft and shaft retainer. Lubricant oil is stored in an oil storage space in a gear case attached to the housing. A cooling water passage through which cooling water to cool the lubricant oil passes is formed in the gear case. A controller controls the flow rate of the cooling fluid, so that the temperature of the lubricant oil in the oil storage space is kept constant. With this configuration, when the bearing portions are fixed in the axial direction with respect to the rotary shafts and the shaft retainers, it is possible to prevent load from being applied to the bearing portions in the axial direction.

Abstract: The rotary vacuum pump includes a pump housing, a rotary shaft, a thrust movement restriction mechanism and a first elastic member. The pump housing has therein a pump chamber. The rotary shaft has thereon a rotor rotatably disposed in the pump chamber. When the rotor is rotated with the rotary shaft, gas in the pump chamber is pumped thereby to draw gas into the pump chamber. The thrust movement restriction mechanism is provided for allowing the rotor to displace in the pump chamber in one thrust direction due to thermal expansion thereof during the operation of the rotary vacuum pump. The first elastic member is provided for urging the rotary shaft in the other thrust direction opposite to the one thrust direction.

Abstract: A screw pump is provided with a pair of screw rotors serving as fluid transfer bodies. With respect to a rotation angle (x) around an axis of each of the screw rotors, a change of a lead angle (?) from a winding start angle (0), which is the rotation angle (x) corresponding to a leading end of a spiral groove, to a winding end angle (E), which is the rotation angle (x) corresponding to a trailing end of the spiral groove, can be expressed by a lead angle change function ?(x). The lead angle change function ?(x) is structured by a combination of a plurality of change functions ?1(x) and ?2(x) having different manners of changing. It is possible to arbitrarily set a manner in which the lead angle (?) changes in accordance with a combination of a plurality of change functions ?1(x) and ?2(x). Therefore, it is possible to arbitrarily set a fluid compression characteristic of the pump in a relation with an axial length (L) of the screw rotor.

Abstract: A vacuum pump includes a housing assembly having an oil-reservoir chamber in which a lubricating oil is stored; a pair of screw rotors disposed in the housing assembly and engaged with each other; a pair of rotary shafts connected to the rotors, respectively; a plurality of bearings supporting each of the rotary shafts and having an opening; an oil-feed pump for feeding the lubricating oil from the oil-reservoir chamber to the bearing; an oil-circulation passage provided for circulating the lubricating oil from the oil-feed pump to the oil-reservoir chamber through the bearing; a cover provided at the opening of the bearing to close the opening of the bearing with a clearance remained, the cover permitting the lubricating oil to enter the bearing through the clearance; and an oil-escape passage provided adjacent to the bearing for returning to the oil-reservoir chamber the lubricating oil not entering the bearing.

Abstract: A fluid pump system has a cover, a fluid pump and a conduit. An inside of the cover is divided into a main chamber and a sub chamber. The fluid pump is accommodated in the main chamber. The conduit extends from the fluid pump to an outside of the cover through the sub chamber.

Abstract: A method for controlling the operation of a vacuum pump when stopping the gas transferring operation thereof, the vacuum pump having a housing in which a pump chamber is formed and a gas transferring body which is rotatably disposed in the pump chamber for transferring gas, the method comprises the steps of reducing rotational speed of the gas transferring body to a first preset speed below a second preset speed that is lower than a normal speed of the gas transferring body during normal gas transferring operation of the vacuum pump, maintaining the speed of the gas transferring body below the second preset speed, and stopping the rotation of the gas transferring body when the temperature of the housing reaches a predetermined temperature which is lower than that of the housing during the normal gas transferring operation of the vacuum pump.

Abstract: A vacuum pump includes a housing assembly having an oil-reservoir chamber in which a lubricating oil is stored; a pair of screw rotors disposed in the housing assembly and engaged with each other; a pair of rotary shafts connected to the rotors, respectively; a plurality of bearings supporting each of the rotary shafts and having an opening; an oil-feed pump for feeding the lubricating oil from the oil-reservoir chamber to the bearing; an oil-circulation passage provided for circulating the lubricating oil from the oil-feed pump to the oil-reservoir chamber through the bearing; a cover provided at the opening of the bearing to close the opening of the bearing with a clearance remained, the cover permitting the lubricating oil to enter the bearing through the clearance; and an oil-escape passage provided adjacent to the bearing for returning to the oil-reservoir chamber the lubricating oil not entering the bearing.

Abstract: A vacuum pump having a rotary shaft that is rotated by a drive source has a main pump and a sub pump. The main pump includes a pump chamber and a gas transferring body that is located in the pump chamber. The main pump is driven by the drive source through the rotary shaft for transferring gas to an exhaust space. The sub pump is connected to the exhaust space for partially exhausting the gas from the exhaust space. The sub pump is driven by the same drive source. The displacement volume of the sub pump is smaller than that of the main pump.

Abstract: A cooling unit which contains refrigerant for exchanging heat with an object member of cooling includes a refrigerant passage and cooling means. The refrigerant passage allows the refrigerant to circulate therethrough. The cooling means communicates with the refrigerant passage for supplying the refrigerant passage with the refrigerant. The cooling means includes a refrigeration circuit, a compressor, a condenser, decompression means, an evaporator, a refrigerant supply path, a refrigerant return path, refrigerant control means and first pressure control means. The refrigerant control means has an on mode which allows the refrigerant to circulate through the refrigerant passage at a flow rate which enables the refrigerant to maintain gas-liquid two-phase flow by allowing the condenser to communicate with the refrigerant passage, and an off mode which prevents the refrigerant from circulating through the refrigerant passage by preventing the condenser from communicating with the refrigerant passage.

Abstract: A diaphragm pump includes a diaphragm, a diaphragm case and a driver. The diaphragm has a center point and an outer peripheral portion. The diaphragm case supports the diaphragm at the outer peripheral portion thereof, thereby defining a pump chamber in the diaphragm case. The driver holds the diaphragm at the center point thereof. The diaphragm is deformed as the driver is reciprocated, thereby accomplishing a fluid to flow into and to be discharged out of the pump chamber. The driver includes a fitting member and a flange. The fitting member fits the diaphragm and has a first surface for contacting the diaphragm. The flange is formed outside the fitting member. The flange has a second surface for contacting the diaphragm when the diaphragm is deformed toward the pump chamber. The second surface has a first convex surface region which is formed continuously with the first surface.

Abstract: A vacuum pump has a pump mechanism section that performs evacuation to set a space to be evacuated to a predetermined degree of vacuum and an electric motor section for driving the pump mechanism section. A controller of the vacuum pump executes deceleration control to decrease a rotational speed of the electric motor section when an increase in load torque of the vacuum pump per unit time abruptly changes upward.

Abstract: A fluid pump system has a cover, a fluid pump and a conduit. An inside of the cover is divided into a main chamber and a sub chamber. The fluid pump is accommodated in the main chamber. The conduit extends from the fluid pump to an outside of the cover through the sub chamber.

Abstract: A Roots pump rotates a plurality of rotors by a pair of rotary shafts to draw gas. Each rotary shaft extends through a rear housing member of the Roots pump. An annular shaft seal is fitted around each rotary shaft and is received in a recess formed in the rear housing member. A helical groove is formed in a circumferential side of each rotary shaft. Each helical groove urges oil between the circumferential side of the associated shaft seal and the circumferential wall of the recess to move from a side corresponding to pump chambers toward a gear accommodating chamber when the associated rotary shaft rotates. This preferably prevents oil from leaking to the pump chambers.

Abstract: A vacuum pump having a rotary shaft that is rotated by a drive source has a main pump and a sub pump. The main pump includes a pump chamber and a gas transferring body that is located in the pump chamber. The main pump is driven by the drive source through the rotary shaft for transferring gas to an exhaust space. The sub pump is connected to the exhaust space for partially exhausting the gas from the exhaust space. The sub pump is driven by the same drive source. The displacement volume of the sub pump is smaller than that of the main pump.

Abstract: A vacuum pump has an oil housing, which defines a pump chamber and an oil zone adjacent to the pump chamber. A rotary shaft extends from the pump chamber through the oil housing and projects to the oil zone. A stopper is attached to the rotary shaft to integrally rotate with the rotary shaft. The stopper prevents oil from entering the pump chamber. The vacuum pump draws gas by operating a gas conveying body in the pump chamber through rotation of the rotary shaft. When the rotary shaft shifts from an operation state to a stopped state, the pressure difference occurs between the pump chamber and the oil zone. Rotation of the rotary shaft is controlled such that the pressure difference becomes maximum before the rotary shaft completely stops.

Abstract: A Roots pump rotates a plurality of rotors by a pair of rotary shafts to draw gas. Each rotary shaft extends through a rear housing member of the Roots pump. An annular shaft seal is fitted around each rotary shaft and is received in a recess formed in the rear housing member. A helical groove is formed in a circumferential side of each rotary shaft. Each helical groove urges oil between the circumferential side of the associated shaft seal and the circumferential wall of the recess to move from a side corresponding to pump chambers toward a gear accommodating chamber when the associated rotary shaft rotates. This preferably prevents oil from leaking to the pump chambers.