Abstract: In an internal gear pump of the present invention, a first angle that is formed by a first straight line that connects a rotation axis of an inner rotor to a tooth tip portion of an external tooth in the rotational direction of the inner rotor and an outer rotor, and a second straight line that connects the rotation axis to a meshing portion of the external tooth is not less than 1.4 times the size and not more than 1.8 times the size of a second angle that is formed by a third straight line that connects the rotation axis to a tooth bottom of the external tooth, and the second straight line.

Abstract: In an internal gear pump of the present invention, a first angle that is formed by a first straight line that connects a rotation axis of an inner rotor to a tooth tip portion of an external tooth in the rotational direction of the inner rotor and an outer rotor, and a second straight line that connects the rotation axis to a meshing portion of the external tooth is not less than 1.4 times the size and not more than 1.8 times the size of a second angle that is formed by a third straight line that connects the rotation axis to a tooth bottom of the external tooth, and the second straight line.

Abstract: In pump rotors and used in an internal gear pump, which includes an inner pump rotor having outer gear teeth; an outer pump rotor having inner gear teeth that mesh with the outer gear teeth ; and a casing having a pumping-in port through which a fluid is pumped in, and a pumping-out port through which the fluid is pumped out, and pumps in and pumps out the fluid by changing the cell volume formed between gear tooth surfaces of the rotors and so as to carry the fluid when the rotors and mesh with each other and rotate, the rotors are formed from a sintered material of Fe—Cu—C and have a density of not less than 6.6 g/cm3 and not more than 7.1 g/cm3, and the outer circumferential surface of the outer pump rotor and the end surfaces perpendicular to rotation axes of the rotors and are non-grinded surface and have a ten point height of irregularities Rz of not less than 4 ?m and not more than 10 ?m.

Abstract: An oil pump rotor assembly is disclosed. An inner rotor formed with n external teeth is based on cycloid curves which are generated by a first circumscribed-rolling circle and a first inscribed-rolling circle by rolling the first circumscribed-rolling circle and first inscribed-rolling circle along an inner base circle. An outer rotor formed with n+1 internal teeth (n+1 is the number of teeth) is based on cycloid curves which are generated by a second circumscribed-rolling circle and a second inscribed-rolling circle by rolling the second circumscribed-rolling circle and second inscribed-rolling circles along an outer base circle.

Abstract: A crankshaft and an mounting hole have two main circular arc parts on the same circle; and two connecting parts for connecting the adjacent main circular arc parts, and have a cross-sectional shape in which the connecting parts facing each other are substantially parallel. The connecting parts of the mounting hole are formed in the shape of a large circular arc which projects inward. The torque of the crankshaft is transmitted to the mounting hole in a state where the connecting parts of the crankshaft and the connecting parts of the mounting hole which are formed in the shape of a large circular arc come into line contact with each other; therefore, the value of any local stress generated in the mounting hole can be reduced.

Abstract: A rotor pump assembly is disclosed which reduces noise emitted from an oil pump while preventing pumping performance and mechanical efficiency thereof from being decreased by properly forming the profiles of teeth of an inner rotor and an outer rotor which are engageable with each other. The tooth profile of an inner rotor and/or an outer rotor has curved lines obtained by dividing a cycloid curve into two segments to be separated from each other, and in which the separated segments are smoothly connected to each other using a straight line or a curve.

Abstract: A crankshaft and an mounting hole have two main circular arc parts on the same circle; and two connecting parts for connecting the adjacent main circular arc parts, and have a cross-sectional shape in which the connecting parts facing each other are substantially parallel. The connecting parts of the mounting hole are formed in the shape of a large circular arc which projects inward. The torque of the crankshaft is transmitted to the mounting hole in a state where the connecting parts of the crankshaft and the connecting parts of the mounting hole which are formed in the shape of a large circular arc come into line contact with each other; therefore, the value of any local stress generated in the mounting hole can be reduced.

Abstract: In pump rotors and used in an internal gear pump, which includes an inner pump rotor having outer gear teeth; an outer pump rotor having inner gear teeth that mesh with the outer gear teeth; and a casing having a pumping-in port through which a fluid is pumped in, and a pumping-out port through which the fluid is pumped out, and pumps in and pumps out the fluid by changing the cell volume formed between gear tooth surfaces of the rotors and so as to carry the fluid when the rotors and mesh with each other and rotate, the rotors are formed from a sintered material of Fe—Cu—C and have a density of not less than 6.6 g/cm3 and not more than 7.1 g/cm3, and the outer circumferential surface of the outer pump rotor and the end surfaces perpendicular to rotation axes of the rotors and are non-grinded surface and have a ten point height of irregularities Rz of not less than 4 ?m and not more than 10 ?m.

Abstract: A rotor pump assembly is disclosed which reduces noise emitted from an oil pump while preventing pumping performance and mechanical efficiency thereof from being decreased by properly forming the profiles of teeth of an inner rotor and an outer rotor which are engageable with each other. The tooth profile of an inner rotor and/or an outer rotor has curved lines obtained by dividing a cycloid curve into two segments to be separated from each other, and in which the separated segments are smoothly connected to each other using a straight line or a curve.

Abstract: An oil pump rotor assembly is disclosed. An inner rotor formed with n external teeth is based on cycloid curves which are generated by a first circumscribed-rolling circle and a first inscribed-rolling circle by rolling the first circumscribed-rolling circle and first inscribed-rolling circle along an inner base circle. An outer rotor formed with n+1 internal teeth (n+1 is the number of teeth) is based on cycloid curves which are generated by a second circumscribed-rolling circle and a second inscribed-rolling circle by rolling the second circumscribed-rolling circle and second inscribed-rolling circles along an outer base circle.

Abstract: An oil pump rotor assembly includes an inner rotor (20) having “n” external teeth (“n” is a natural number), and an outer rotor (10) having (n+1) internal teeth which are engageable with the external teeth, the oil pump rotor assembly being used in an oil pump which, during rotation of the inner and outer rotors (20, 10), draws and discharges fluid by volume change of cells (R) formed between the inner and outer rotors (20, 10).

Abstract: An oil pump rotor assembly for an oil pump which enables reduction of noise while preventing pump performance and mechanical efficiency from being degraded. In this oil pump rotor assembly, the tooth tip profile of each of at least one of external teeth of an inner rotor and internal teeth of an outer rotor the inner rotor is formed such that a base cycloid curve is divided at a midpoint thereof to obtain two tooth curve segments, and the two tooth curve segments are separated by a predetermined distance along the circumference of a base circle or in the direction of a tangent of the base cycloid curve drawn at the midpoint thereof and are smoothly connected to each other using a curve or a straight line.

Abstract: An internal gear oil pump rotor assembly which enables the construction of an oil pump that is compact and has high performance. In the oil pump rotor assembly having an inner rotor and an outer rotor, the number of teeth “Zi” of the inner rotor with trochoid tooth profiles is set to be equal to or fewer than “6”, and a ratio Si/So is set so as to satisfy the following inequalities: 0.8?Si/So?1.3, where Si is a cross-sectional area of one external tooth which is formed outside a root circle that is formed along the bottoms of the external teeth of the inner rotor, and So is a cross-sectional area of one internal tooth which is formed inside a root circle that is formed along the bottoms of the internal teeth of the outer rotor.

Abstract: An oil pump emits less noise by properly forming the profiles of teeth of an inner rotor and an outer rotor thereof which engage each other, whereby decreasing sliding resistance and rattle between the tooth surfaces of the rotors. The rotors of the oil pump are formed so the inner rotor having “n” teeth is formed such that the tooth tip profile and tooth space profile thereof are formed using cycloid curves which are formed by rolling a first circumscribed-rolling circle and a first inscribed-rolling circle along a base circle, respectively, and the outer rotor having “n+1” teeth is formed such that the tooth tip profile and tooth space profile thereof are formed using cycloid curves which are formed by rolling a second circumscribed-rolling circle and a second inscribed-rolling circle along a base circle, respectively, and in such a manner that the following equations are satisfied: øBo=øBi; øDo=øDi·(n+1)/n+t·(n+1)/(n+2); and øAo=øAi+t/(n+2).

Abstract: An oil pump rotor assembly for an oil pump which enables reduction of noise while preventing pump performance and mechanical efficiency from being degraded. In this oil pump rotor assembly, the tooth tip profile of each of at least one of external teeth of an inner rotor and internal teeth of an outer rotor the inner rotor is formed such that a base cycloid curve is divided at a midpoint thereof to obtain two tooth curve segments, and the two tooth curve segments are separated by a predetermined distance along the circumference of a base circle or in the direction of a tangent of the base cycloid curve drawn at the midpoint thereof and are smoothly connected to each other using a curve or a straight line.

Abstract: An internal gear oil pump rotor assembly which enables the construction of an oil pump that is compact and has high performance. In the oil pump rotor assembly having an inner rotor and an outer rotor, the number of teeth “Zi” of the inner rotor with trochoid tooth profiles is set to be equal to or fewer than “6”, and a ratio Si/So is set so as to satisfy the following inequalities: 0.8≦Si/So≦1.3, where Si is a cross-sectional area of one external tooth which is formed outside a root circle that is formed along the bottoms of the external teeth of the inner rotor, and So is a cross-sectional area of one internal tooth which is formed inside a root circle that is formed along the bottoms of the internal teeth of the outer rotor.

Abstract: An oil pump emits less noise by properly forming the profiles of teeth of an inner rotor and an outer rotor thereof which engage each other, whereby decreasing sliding resistance and rattle between the tooth surfaces of the rotors.

Abstract: An oil pump rotor in which there is formed an inner rotor 10 having n teeth, the tips of the teeth prescribed by an epicycloid curve generated by a first outer rotating circle Ei which rotates along the base circle Bi of inner rotor 10, and the tooth spaces prescribed by a hypocycloid curve generated by a first rotating circle Hi which turns along the base circle Bi of inner rotor 10, and an outer rotor 20 having n+1 teeth, the tooth spaces prescribed by an epicycloid curve generated by a second rotating circle Eo which turns along the base circle Bo of outer rotor 20 and the tips of the teeth prescribed by a hypocycloid curve generated by a second inner rotating circle Ho which rotates along the base circle Bo of outer rotor 20; wherein each of the rotors are formed to satisfy:Do>Di, di>dowhere Di, di, Do, and do designate the diameters of Ei, Hi, Eo, and Ho, respectively.

Abstract: The present invention relates to an oil pump rotor provided with an inner rotor 10 to which n (n is a natural number) outer teeth 11 are formed, an outer rotor 20 to which n+1 inner teeth 21 are formed which engage with each of the outer teeth 11, and a casing 30 in which an intake port 31 for taking up fluid and an expulsion port 32 for expelling fluid are formed, wherein:the outer teeth of inner rotor are formed by alternately combining an epicycloid curve and a hypocycloid curve, the epicycloid curve being generated as an orbit of the point on a circle which rolls along the outside of the base circle without slipping, and the hypocycloid curve being generated as an orbit of a point on a circle which rolls along the inside of the base circle without slipping; the alternately combined curve being generated under the following condition, where E is the diameter of the circle which rolls along the outside of the base circle, and H is the diameter of the circle which rolls along the inside of the base circle:0.

Abstract: The present invention relates to an oil pump rotor for an oil pump provided with an inner rotor 10 to which n (n is a natural number) outer teeth 11 are formed, an outer rotor 20 to which n+1 inner teeth 21 are formed which engage with each of the outer teeth 11, and a casing 30 in which an intake port 31 for taking up fluid and an expulsion port 32 for expelling fluid are formed, wherein:the outer teeth 11 of inner rotor 10 are formed along an envelope described by a generated group of circles having centers positioned on a trochoid curve generated within the limits satisfying the following expression:0.15.ltoreq.n.multidot.R/(p.multidot.D).ltoreq.0.25where D is the diameter of the circle which passes through each of the tips of the outer teeth and R is the radius of the generated circle measured in millimeters, while p is .pi..