Plural screw positive displacement machines

A plural screw, positive displacement machine, said machine comprising:

• a housing having at least two intersecting bores;
• and a male rotor and a female rotor mounted for rotation in said housing wherein, each said rotor has an axis and a pitch circle that extends around the axis and, wherein:
• each said rotor is located in a separate one of the bores of said housing;
• said male rotor is formed with a plurality of circumferentially spaced apart lobes, each said lobe extending outwardly beyond the pitch circle of said male rotor and helically along said male rotor;
• said female rotor is formed with a plurality of circumferentiallly spaced apart lobes that define depressions that extend inwardly from an outer surface of said female rotor, inwardly relative to the pitch circle of said female rotor and helically along said female rotor and said female rotor is formed with a number of said lobes so that the number of depressions defined by said lobes is different than the number of said lobes formed on said male rector;
• said housing is shaped and said rotors are positioned so that said lobes of said male rotor mesh into the depressions of said female rotor;
• and
• said male rotor and said female rotor are shaped so that:
• portions of said lobes of said male rotor extend both outwardly and inwardly of the pitch circle of said make rotor;
• portions of said lobes of said female rotor extend both outwardly and inwardly of the pitch circle of said female rotor;
• and said lobes of said male and female rotors are defined by the same rack, wherein, said lobes of said male rotor are defined by curving the rack about the axis of said male rotor and the depressions of said female rotor are defined by curving the rack around the axis of said female rotor and the rack has a portion which defines high pressure flanks of said lobes of said male rotor and said female rotor that is generated by a conjugate action between said rotors, and the portions of said lobes of said male rotor that extend inwardly of the pitch circle of the male rotor and the portions of said lobes of said female rotor that extend outwardly of the pitch circle of said female rotor are defined by the rack.

A plural screw, positive displacement machine, said machine comprising:

• a housing having at least two intersecting bores;
• and
• a male rotor and a female rotor mounted for rotation in said housing wherein, each said rotor has an axis and a pitch circle that extends around the axis and, wherein:
• each said rotor is located in a separate one of the bores of said housing;
• said male rotor is formed with a plurality of circumferentially spaced apart lobes, each said lobe extending outwardly beyond the pitch circle of said male rotor and helically along said male rotor;
• said female rotor is formed with a plurality of circumferentially spaced apart lobes that define depressions that extend and inwardly relative to the pitch circle of said female rotor and helically along said female rotor and said female rotor is formed with a number of said lobes so that the depressions defined by said lobes are different in number than the number of said lobes formed said male rotor;
• said housing is shaped and said rotors are positioned so that said lobes of each said male rotor mesh into the depressions of said female rotor with which said male rotor is adjacent;
• and
• said male rotor and said female rotor are shaped so that portions of said lobes of said male rotor extending beyond the pitch circle of said male rotor and portions of said lobes of said female rotor extending inwardly from the pitch circle of said female rotor are defined by the same rack, wherein, said lobes of said male rotor are defined by curving the rack about the axis of said male rotor and the depressions of said female rotor are defined by curving the rack around the axis of said female rotor and the rack has a portion which defines high pressure flanks of said lobes of said male rotor that is generated of said lobes of said male rotor that is generated by a conjugate action between the rotors and a portion that defines the portions of said lobes that extend outwardly of the pitch circle of said male rotor that collectively have:
• a first straight line section that extends outwardly from a first point equivalent to the perimeter of the pitch circle of said male rotor;
• a first curved section that extends from the first straight line section, the firs t curved section of the type axp+byq=1, where p=0.43;
• a second curved section that extends from the first curved section, the second curved section of the type ax−byq=1, where q=0.25;
• a third curved section that extends from the second curved section, the third curved section of the type ax+byq=1, where q=0.75;
• and
• a second straight line section that extends from the third curved section to a second point equivalent to the perimeter of the pitch circle of said male rotor, the second point being spaced from the first point.

A plural screw, positive displacement machine, said machine comprising:

• a housing having at least two intersecting bores;
• and
• a male rotor and a female rotor mounted for rotation in said housing wherein, each said rotor has an axis and a pitch circle that extends around the axis and, wherein:
• each said rotor is located in a separate one of the bores of said housing;
• said male rotor is formed with a plurality of circumferentially spaced apart lobes, each said lobe extending outwardly beyond the pitch circle of said male rotor and helically along said male rotor;
• said female rotor is formed with a plurality of circumferentially spaced apart lobes that define depressions that extend inwardly from an outer surface of said female rotor and inwardly relative to the pitch circle of said female rotor and helically along said female rotor and said female rotor is formed with a number of said lobes so that the depressions defined by said lobes are different in number than the number of lobes of said male rotor;
• said housing is shaped and said rotors are positioned so that said lobes of said male rotor mesh into the depressions of said female rotor;
• and
• said male rotor and said female rotor are shaped so that portions of said lobes of said male rotor extending beyond the pitch circle of said male rotor and portions of said lobes of said female rotor extending inwardly from the pitch circle of said female rotor are defined by the same rack wherein, said lobes of said male rotor are defined by curving the rack about the axis of said male rotor and the depressions of said female rotor are defined by curving the rack around the axis of said female rotor and the rack has:
• a portion which defines high pressure flanks of said lobes of said male and female rotors the portion having a generalized parabolic profile;
• and
• a portion which defines flanks of said lobes of said male rotor opposite the high pressure flanks that has a curvature of the type axp+byq=1, wherein:
• p=0.43±10%;
• 1±10%;
• and a=b.

A plural screw, positive displacement machine, said machine comprising:

• a housing having at least two intersecting bores;
• and
• a male rotor and a female rotor mounted for rotation in said housing wherein, each said rotor has an axis and a pitch circle that extends around the axis and:
• each said rotor is located in a separate one of the bores of said housing;
• said male rotor is formed with a plurality of circumferentially spaced apart lobes, each said lobe extending outwardly beyond the pitch circle of said male rotor and helically along said male rotor;
• said female rotor is formed with a plurality of circumferentially spaced apart lobes that define depressions that extend inwardly from an outer surface of said female rotor and inwardly relative to the pitch circle of said female rotor and helically along said female rotor;
• said housing is shaped so that said lobes of said male rotor mesh into the depressions of said female rotor;
• and
• said lobes of said male rotor are defined by curving a rack about the axis of said male rotor and the depressions of said female rotor are defined by curving the rack has a curved portion which defines a major portion of a first flank of each said lobe of said rotor and the curved portion has:
• an arcuate section proximal to the pitch circle of said male rotor having a curvature the type ax+byq=1, where q=0.75;
• and an arcuate section distal to the pitch circle of said male rotor having a curvature of the type ax+byq=1, where q=0.25.

A plural screw, positive displacement machine, said machine comprising:

• a housing having at least two intersecting bores;
• and
• a male rotor and a female rotor mounted for rotation in said housing wherein, each said rotor has an axis and a pitch circle that extends around the axis and:
• each said rotor is located in a separate one of the bores of said housing;
• said male rotor is formed with a plurality of circumferentially spaced apart lobes, each said lobe extending outwardly beyond the pitch circle of said male rotor and helically along said male rotor;
• said female rotor is formed with a plurality of circumferentially spaced apart lobes that define depressions that extend inwardly from an outer surface of said female rotor and inwardly relative to the pitch circle of said female rotor and helically along said female rotor;
• said housing is shaped so that said lobes of said male rotor mesh into the depressions of said female rotor;
• and
• said male rotor and said female rotor are shaped so that portions of said lobes of said male rotor that extend beyond the pitch circle of said male rotor and portions of said lobes of said female rotor extending inwardly from the pitch circle of said female rotor are defined by curving the rack around the axis of said male rotor and the depressions of said female rotor being defined by curving the rack around the axis of the female rotor, the rack having a portion that defines high pressure flanks of said lobes of said male rotor that is generated by a conjugate action between said rotors and a portion of the rack that defines the portions of said lobes that extend outwardly of the pitch circle of said male rotor, has:
• a first straight line section that extends outwardly from a first point equivalent to the perimeter of the pitch circle of said male rotor;
• a first curved section that extends from the first straight line section, the first curved section of the type axp+byq=1, where p=0.43;
• a second curved section that extends from the first curved section, the second curved section having a cycloidal profile;
• and
• a second straight line section that extends from the second curved section to a second point equivalent to the perimeter of the pitch circle of said male rotor, the second point being spaced from the first point.