Abstract: A screw rotor is for use in a screw pump that pumps fluid by rotation of a pair of screw rotors engaged with each other in a rotor housing. The screw rotor includes a multiple-thread portion for pump suction side and a single-thread portion for pump discharge side. The screw rotor is formed so that the tooth profile of the multiple-thread portion is connected to the tooth profile of the single-thread portion through a boundary plane that is perpendicular to the rotation axis of the screw rotor. The first curved portion coincides with the third curved portion in the boundary plane.

Abstract: A cross section of a tooth profile of a first screw rotor (17) perpendicular to the rotor axis includes a tooth top arc (A1B1), a tooth bottom arc (C1D1), a first curve (A1C1), and a second curve (B1D1). The first curve (A1C1) is a first trochoidal curve that connects a first end (A1) of the tooth top arc (A1B1) to a second end (C1) of the tooth bottom arc (C1D1). The second curve (B1D1) connects the second end (B1) of the tooth top arc (A1B1) to the first end (D1) of the tooth bottom arc (C1D1). The second curve (B1D1) is a composite curve formed by an involute curve (B1E1) and a second trochoidal curve (E1D1), which extend continuously from each other at a first intersection point (E1). A screw pump (11) thus suppresses leakage of fluid with improved performance.

Abstract: A cross section of a tooth profile of a first screw rotor (17) perpendicular to the rotor axis includes a tooth top arc (A1B1), a tooth bottom arc (C1D1), a first curve (A1C1), and a second curve (B1D1). The first curve (A1C1) is a first trochoidal curve that connects a first end (A1) of the tooth top arc (A1B1) to a second end (C1) of the tooth bottom arc (C1D1). The second curve (B1D1) connects the second end (B1) of the tooth top arc (A1B1) to the first end (D1) of the tooth bottom arc (C1D1). The second curve (B1D1) is a composite curve formed by an involute curve (B1E1) and a second trochoidal curve (E1D1), which extend continuously from each other at a first intersection point (E1). A screw pump (11) thus suppresses leakage of fluid with improved performance.

Abstract: A pneumatic tire has an annular bead core, a bead filler, a carcass ply rolled up in such a manner as to pinch the bead core and the bead filler, and a white rubber arranged in an outer side of the carcass ply of the side wall portion. The white rubber has an inner peripheral end positioned in an outer side of the bead filler. The bead filler has a main body rubber portion running into the bead core from a leading end, and a soft rubber portion constructing a part of an outer surface of the bead filler and positioned in an inner side of the inner peripheral end of the white rubber. The soft rubber portion is harder than the white rubber and softer than the main body rubber portion.

Abstract: A housing (2) of a Roots pump (1) supports a drive shaft (3) and a driven shaft (4) with radial bearings (32, 33) so as to be rotatable. The housing (2) is formed by joining an upper housing member (20) to a lower housing member (10). The lower housing member (10) has lower bearing support portions (13), and the upper housing member (20) has upper bearing support portions (23). Opening edges (13a) of each lower bearing support portion (13) are positioned above the centers (P1) of the bearings (32, 33). An opening width (T1) of each lower bearing support portion (13) is smaller than the diameter (D1) of the bearings (32, 33). This structure suppresses the bearings (32, 33) from being separated from the lower housing member (10) during an assembling operation of the fluid machine.

Abstract: A diaphragm pump for pumping a fluid includes a diaphragm and a driver. The diaphragm has a first surface and a second surface. The driver includes a support portion and is connected to the diaphragm via the support portion. The driver is reciprocated to deform the diaphragm thereby performing a pumping action. The support portion includes a first supporting surface for supporting the first surface and a second supporting surface for supporting the second surface. The support portion allows the diaphragm to slidingly move along an interval between the first and second supporting surfaces when the diaphragm is deformed.

Abstract: A housing of a Roots pump is configured by joining a lower housing member and an upper housing member that are separable from each other. With the upper and lower housing members joined together, an upper accommodating portion and a lower accommodating portion form a front bearing accommodating portion and a rear bearing accommodating portion, which accommodate whole bearings, respectively. The Roots pump further includes bearing holders attached to the bearings and fixed to the lower housing member so that the bearings are received in the lower accommodating portion in a positioned state.

Abstract: A diaphragm unit includes a plurality of diaphragms which are layered on top of each other. A case and the diaphragm unit define a pump chamber. The diaphragm unit has a first surface and a second surface on the side opposite to the first surface. A support member for supporting the diaphragm unit has a first support surface for supporting the first surface and a second support surface for supporting the second surface. The support member allows the diaphragms to slide between the first support surface and the second support in case here the diaphragm unit changes its form. Thus, the durability of the diaphragm is improved.

Abstract: A screw pump includes a housing and a pair of intermeshing screw rotors. An end face of the rotor adjacent to an inlet port of the housing is provided with an inlet opening. Each rotor has a first portion whose lead angle changes. The first portions and the housing cooperate to form an inlet space. During rotation of the rotors, communication between the inlet space and the inlet port is blocked by the first portions and the housing thereby to form a closed pump space adjacent to the inlet space. Volume of the pump space is set smaller than the maximum volume of the inlet space. A closure member is provided which covers at least a part of the inlet openings. The closure member closes the inlet space when the volume of the inlet space exceeds that of the pump space.

Abstract: A screw pump includes a housing and a pair of intermeshing screw rotors. The housing has an inlet port and an outlet port. Each rotor has a first portion whose lead angle decreases. The first portion and the housing form an inlet space and a pump space. Winding angle of the first portion has a first region and a second region. The first region is located in a predetermined range from the end on the first portion adjacent to the inlet port toward the outlet port. The second region is located adjacent to the first region. Reduction rate of the lead angle of the first portion in the first region is set smaller than that in the second region. The maximum lead angle of the first portion is set smaller than a lead angle which decreases at a constant rate in the first region and the second region.

Abstract: A diaphragm pump for pumping a fluid includes a housing, a pump chamber defined in the housing, a first diaphragm for sealing the pump chamber, a pressure control chamber defined in the housing adjacent to the pump chamber via the first diaphragm, a second diaphragm for sealing the pressure control chamber, a drive mechanism operable to deform the first and second diaphragms, an introduction passage for introducing into the pressure control chamber a part of the fluid that is discharged from the pump chamber, and a pressure regulating valve disposed in the introduction passage for adjusting a pressure in the pressure control chamber to a medium pressure between a suction pressure and a discharge pressure.

Abstract: A screw pump includes a housing and a pair of intermeshing screw rotors. The housing has an inlet port and an outlet port. Each rotor has a first portion whose lead angle decreases. The first portion and the housing form an inlet space and a pump space. Winding angle of the first portion has a first region and a second region. The first region is located in a predetermined range from the end on the first portion adjacent to the inlet port toward the outlet port. The second region is located adjacent to the first region. Reduction rate of the lead angle of the first portion in the first region is set smaller than that in the second region. The maximum lead angle of the first portion is set smaller than a lead angle which decreases at a constant rate in the first region and the second region.

Abstract: A screw pump includes a housing and a pair of intermeshing screw rotors. An end face of the rotor adjacent to an inlet port of the housing is provided with an inlet opening. Each rotor has a first portion whose lead angle changes. The first portions and the housing cooperate to form an inlet space. During rotation of the rotors, communication between the inlet space and the inlet port is blocked by the first portions and the housing thereby to form a closed pump space adjacent to the inlet space. Volume of the pump space is set smaller than the maximum volume of the inlet space. A closure member is provided which covers at least a part of the inlet openings. The closure member closes the inlet space when the volume of the inlet space exceeds that of the pump space.

Abstract: A diaphragm unit includes a plurality of diaphragms which are layered on top of each other. A case and the diaphragm unit define a pump chamber. The diaphragm unit has a first surface and a second surface on the side opposite to the first surface. A support member for supporting the diaphragm unit has a first support surface for supporting the first surface and a second support surface for supporting the second surface. The support member allows the diaphragms to slide between the first support surface and the second support in case here the diaphragm unit changes its form. Thus, the durability of the diaphragm is improved.

Abstract: A diaphragm pump for pumping a fluid includes a housing, a pump chamber defined in the housing, a first diaphragm for sealing the pump chamber, a pressure control chamber defined in the housing adjacent to the pump chamber via the first diaphragm, a second diaphragm for sealing the pressure control chamber, a drive mechanism operable to deform the first and second diaphragms, an introduction passage for introducing into the pressure control chamber a part of the fluid that is discharged from the pump chamber, and a pressure regulating valve disposed in the introduction passage for adjusting a pressure in the pressure control chamber to a medium pressure between a suction pressure and a discharge pressure.

Abstract: A diaphragm pump for pumping a fluid includes a diaphragm and a driver. The diaphragm has a first surface and a second surface. The driver includes a support portion and is connected to the diaphragm via the support portion. The driver is reciprocated to deform the diaphragm thereby performing a pumping action. The support portion includes a first supporting surface for supporting the first surface and a second supporting surface for supporting the second surface. The support portion allows the diaphragm to slidingly move along an interval between the first and second supporting surfaces when the diaphragm is deformed.

Abstract: A pump includes a unit case, a volume-changing body, a support portion, a driver and a seal member. The volume-changing body is accommodated in the unit case for defining a pump chamber. The support portion is provided in the unit case. The driver is connected to the volume-changing body and slidably supported by the support portion. The driver is reciprocated to deform the volume-changing body thereby changing a volume of the pump chamber to perform a pumping action. The seal member is provided between the unit case and the driver for preventing lubricant from leaking from a sliding region between the driver and the support portion to the volume-changing body.

Abstract: A reciprocating pump has an action chamber, a diaphragm, a drive shaft, and a roller. The diaphragm is displaced for changing the volume of the action chamber. A groove is formed on a circumference of the drive shaft. The roller is engaged with the groove and is connected to the diaphragm. When the drive shaft is rotated, the roller is guided by the groove to reciprocate along the axis of the drive shaft. When the roller reciprocates, the diaphragm is displaced along the axis of the drive shaft.

Abstract: The present invention provides pivot 207a of paper edge regulation element 207 that evens up the edges of placed sheets aside from rotation axis 206 of pickup roller 204, forms groove 208 into which rotation axis 206 that has ascended is fitted in paper edge regulation element 207, makes rotation axis 206 fit into groove 208 of paper edge regulation element 207 when pickup roller 204 is lifted to regulate the rotation of paper edge regulation element 207 and makes rotation axis 206 come off groove 208 of paper edge regulation element 207 and become free to rotate when pickup roller 204 is lowered.

Abstract: A synthetic resin needle of reinforced with combustible fibers whose longitudinal directions are arrayed straight or curvilinearly along the axial length of the needle. The reinforcing fibers may be dispersed uniformly in the synthetic resin of the needle, or in such a non-uniform manner that the concentration of the fibers in some portion around the peripheral wall of the needle is so scarce that the inner passage of the needle can be observed from outside.