US4412796A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Helical screw rotor profiles
Assignee: Ingersoll Rand Co
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Filing: 1981-08-25
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Granted: 1983-11-01
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Expires: 2001-08-25
Abstract
Abstract The invention concerns helical- or screw-type driving and driven rotors having lands and intervening grooves for coacting engagement, within a housing of a machine, such as a gas compressor or expander, the rotors having improved, more efficient, profiles. The profiles are defined with contiguous elliptic and involute sections to improve the pressure angle, and the profiles are configured to define rotor-to-rotor sealing surfaces in closure of a compressed gas pocket in which, the pocket gas pressure always urges or torques the driven rotor in the positive or forward-rotary direction.
Inventors
- 👤 James L. Bowman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 08:42
CPC Classifications
F; F01; F01C; F01C1/00; F01C1/08; F01C1/082; F01C1/084; F05; F05B; F05B2250/00; F05B2250/20; F05B2250/25
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
125 words
A rotor, having helical lands and intervening grooves rotatable about an axis for coacting engagement within a machine housing, with a cooperating, meshing rotor, in order that fluid admitted into such housing will be received in said grooves and, due to coacting mesh and rotation of said rotors, will have the pressure thereof altered, wherein: each of said grooves has a leading flank and a trailing flank, relative to a given rotary direction of said rotor; and said leading and trailing flanks of said grooves of said rotor are generally concave; said leading flank is made up of a circular arc at its root, followed by an involute intermediate portion, followed by an elliptical portion which is contiguous with an outermost tip of said rotor.
Claim 2
Dependent Claim
125 words
A rotor, having helical lands and intervening grooves rotatable about an axis for coacting engagement within a machine housing, with a cooperating, meshing rotor, in order that fluid admitted into such housing will be received in said grooves and, due to coacting mesh and rotation of said rotors, will have the pressure thereof altered, wherein: each of said grooves has a leading flank and a trailing flank, relative to a given rotary direction of said rotor; and said leading and trailing flanks of said grooves of said rotor are generally concave; said leading flank is made up of a circular arc at its root, followed by an involute intermediate portion, followed by an elliptical portion which is contiguous with an outermost tip of said rotor.
Claim 3
Dependent Claim
24 words
A rotor, according to claim 1, wherein: a portion of said trailing flank which is contiguous with said leading flank describes a circular arc.
Claim 4
Dependent Claim
20 words
A rotor according to claim 1, wherein: said involute portion is contiguous with said circular arc and said elliptical portion.
Claim 5
Dependent Claim
16 words
A rotor, according to claim 1, wherein: said elliptical portion and said involute portion are contiguous.
Claim 6
Dependent Claim
57 words
A rotor, according to claim 1, wherein: said elliptical portion merges with a land adjacent thereto; said adjacent land further merges with a trailing flank of another most-adjacent groove through another circular arc; and said elliptical portion encompasses a radial arc having an extent which is not less than twice that encompassed by said another circular arc.
Claim 7
Dependent Claim
27 words
A rotor, according to claim 1, wherein: said elliptical portion encompasses an arc which is not less than twice the radial arc encompassed by said circular arc.
Claim 8
Dependent Claim
27 words
A rotor, according to claim 1, wherein: said rotor has a pitch circle centered on said axis; and said elliptical portion lies outside of said pitch circle.
Claim 9
Dependent Claim
16 words
A rotor, according to claim 7, wherein: said involute portion lies inside of said pitch circle.
Claim 10
Dependent Claim
37 words
A rotor, according to claim 1, wherein: said circular arc, involute portion, and elliptical portion comprise three unequal lengths or portions of said leading flank, and said circular arc, comprises a major portion of said leading flank.
Claim 11
Dependent Claim
18 words
A rotor, according to claim 4, wherein: said elliptical portion comprises a minor portion of said leading flank.
Claim 12
Dependent Claim
18 words
A rotor, according to claim 4, wherein: said involute portion comprises a median portion of said leading flank.
Claim 13
Dependent Claim
67 words
A rotor, according to claim 1, wherein: said rotor has a given overall diameter; each of said grooves has a radially innermost point which lies at a common, given radius from said axis, defining for said rotor a minimum groove diameter; and said involute portion extends outwardly, along said leading flank, from a starting point subsisting substantially midway between said overall diameter and said minimum groove diameter.
Claim 14
Dependent Claim
56 words
A rotor, according to claim 12, wherein: said leading flank merges with a land adjacent thereto, defining thereat a flank termination; said circular arc extends into said trailing flank to a point defining an arc termination; and a straight line drawn from said flank termination to said arc termination passes through said involute portion starting point.
Claim 15
Dependent Claim
87 words
A rotor, according to claim 12, wherein: said trailing flank comprises a generated section having leading and trailing points; said elliptical portion has leading and trailing points; and a circular arc drawn from a center at said leading point of said generated section, which bisects said trailing point of said generated section comprises a radius which is substantially exactly twice the radius of a circular arc drawn from a center at said starting point of said involute portion which bisects said trailing point of said elliptical portion.
Claim 16
Dependent Claim
64 words
A rotor, according to claim 12, wherein: one of said leading flanks, and a trailing flank of a groove forward thereof, relative to said given rotary direction, define a rib therebetween; and said rib has a width at the radially outermost surface thereof which is less than one-third the width thereof and thereacross at the location of said starting point of said involute section.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-10-31 | 1987-05-02 | 1987-11-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-10-31 | 1991-05-02 | 1991-11-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-10-31 | 1995-05-02 | 1995-11-01 | $7700.00 | Window Closed / Lapsed |