Abstract: The object of the invention is to provide a screw type fluid machine in which leak of gas is kept in constant, in other words, in which a gap between the screw rotors is kept substantially in constant in a discharging chamber during operation.

Abstract: In a screw type vacuum pump which includes a housing provided with a rotor chamber, a pair of screw rotors in mesh with each other rotably provided in the rotor chamber, a transfer chamber of gas formed between an inner wall of the housing and flutes of the aforesaid pair of screw rotors, and a suction port and an exhaust port communicated to the transfer chamber, the gas being sucked from the suction port into the transfer chamber and exhausted from the exhaust port, by providing the aforesaid exhaust port in a side face of the housing, it is possible to form a larger exhaust port, and a time until the port is blocked with deposits can be prolonged.

Abstract: The invention is directed to provide a liquid pump (lubricant circulation or lubricant supply pump) that is capable of lubricating a machine or apparatus even in a case that a passage supplying a liquid (lubricant) is in a vacuum condition.

Abstract: In a screw type vacuum pump which includes a housing provided with a rotor chamber, a pair of screw rotors in mesh with each other rotably provided in the rotor chamber, a transfer chamber of gas formed between an inner wall of the housing and flutes of the aforesaid pair of screw rotors, and a suction port and an exhaust port communicated to the transfer chamber, the gas being sucked from the suction port into the transfer chamber and exhausted from the exhaust port, by providing the aforesaid exhaust port in a side face of the housing, it is possible to form a larger exhaust port, and a time until the port is blocked with deposits can be prolonged.

Abstract: In screw rotors (21, 22) which are each provided with a screw tooth (211, 221) having a spiral addendum surface portion (211a, 221a) and a deddendum surface portion (211c, 221c), and are used as a pair of male and female, between the addendum surface portion (211a, 221a) and deddendum surface portion (211c, 221c) of the screw tooth (211, 221), there is provided the pitch circumference portion (211p, 221p) which forms a predetermined angle range of circular arc having a definite radius rp on an optional transverse cross section, and the radius of the pitch circumference portion (211p, 221p) is set such that, when the opposing rotors are meshed with each other, out of the meshing clearances between the male and female screw teeth (211, 221), the clearance g1 between the pitch circumference portions (211p, 221p) becomes smaller than the clearances g2, g3, g4 between the other portions.

Abstract: In screw rotors (21, 22) which are each provided with a screw tooth (211, 221) having a spiral addendum surface portion (211a, 221a) and a deddendum surface portion (211c, 221c), and are used as a pair of male and female, between the addendum surface portion (211a, 221a) and deddendum surface portion (211c, 221c) of the screw tooth (211, 221), there is provided the pitch circumference portion (211p, 221p) which forms a predetermined angle range of circular arc having a definite radius rp on an optional transverse cross section, and the radius of the pitch circumference portion (211p, 221p) is set such that, when the opposing rotors are meshed with each other, out of the meshing clearances between the male and female screw teeth (211, 221), the clearance g1 between the pitch circumference portions (211p, 221p) becomes smaller than the clearances g2, g3, g4 between the other portions.

Abstract: A rotary motion to longitudinal motion converting mechanism comprising a passive rack with a plurality of teeth, a plurality of active racks respectively having a plurality of teeth having the same pitch as that of the teeth of the passive rack and meshing with the passive rack, and a plurailty of rotatable crankshafts respectively having eccentric circular portions different in phase from one another and respectively having the active racks supported on the eccentric circular portions in such a manner that the passive rack is moved in its longitudinal direction through the active racks by rotary motions of the plurality of rotatable crankshafts.