US4944655A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Propeller blade of a fiber-reinforced plastic material
Assignee: MTU Motoren und Turbinen Union Friedrichshafen GmbH
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Filing: 1989-05-08
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Granted: 1990-07-31
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Expires: 2009-05-08
Abstract
Abstract A propeller blade of fiber-reinforced plastic with a combined erosion, icing and lightning protection system has a metal shroud fitted to its leading edge, the shroud enclosing a cavity and accommodating a heating conductor at its interior. A ground line of the heating conductor is connected to ground and serves as a lightning conductor.
Inventors
- 👤 Herbert Merz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 22:03
CPC Classifications
B; B64; B64D; B64D45/00; B64D45/02; B64C; B64C11/00; B64C11/16; B64C11/20; B64C11/26; B64D15/00; B64D15/12; F; F04; F04D; F04D29/00; F04D29/26; F04D29/32; F04D29/321; F04D29/324; F04D29/58; F04D29/582; F04D29/584; F05; F05D; F05D2240/00; F05D2240/20; F05D2240/30; F05D2240/303; Y; Y02; Y02T; Y02T50/00; Y02T50/60
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
157 words
Propeller blade having a blade span and positioned at a propeller blade hub including metallic parts, the propeller blade comprising: a fiber reinforced plastic airfoil section; an outer shroud constructed from a thermally and electrically conductive, deformable material forming a leading edge of the plastic airfoil section; cavity means formed by the plastic airfoil section and outer shroud, the cavity means separating the outer shroud and the plastic airfoil section of the blade and extending in a direction of the blade span of the propeller blade; electrical deicing means within the cavity means and in thermal and electrical contact with the outer shroud, the electrical deicing means including a heating conductor and grounding means for electrically grounding the outer shroud; lightning protection means comprising the outer shroud and the grounding means of the electrical deicing means as lightening conductors; and connecting means for connecting the lightening protection means to the metallic parts of the propeller blade hub.
Claim 2
Dependent Claim
157 words
Propeller blade having a blade span and positioned at a propeller blade hub including metallic parts, the propeller blade comprising: a fiber reinforced plastic airfoil section; an outer shroud constructed from a thermally and electrically conductive, deformable material forming a leading edge of the plastic airfoil section; cavity means formed by the plastic airfoil section and outer shroud, the cavity means separating the outer shroud and the plastic airfoil section of the blade and extending in a direction of the blade span of the propeller blade; electrical deicing means within the cavity means and in thermal and electrical contact with the outer shroud, the electrical deicing means including a heating conductor and grounding means for electrically grounding the outer shroud; lightning protection means comprising the outer shroud and the grounding means of the electrical deicing means as lightening conductors; and connecting means for connecting the lightening protection means to the metallic parts of the propeller blade hub.
Claim 3
Dependent Claim
45 words
Propeller blade of claim 1, wherein an inner shroud includes means for conformally fitting the inner shroud to a propeller blade surface and for connecting the inner shroud to the outer shroud, the inner shroud being constructed from a thermally and electrically conductive, deformable material.
Claim 4
Dependent Claim
20 words
Propeller blade of claim 2, wherein the inner shroud is connected to the outer shroud by a roller seam weld.
Claim 5
Dependent Claim
31 words
Propeller blade according to claim 1, wherein the outer shroud comprises a number of sections successively arranged along the leading edge of the blade in a direction of the blade span.
Claim 6
Dependent Claim
28 words
Propeller blade according to claim 1, wherein the heating conductor is a coaxial line having an inner conductor, an insulating layer surrounding it, and a metallic shroud tube.
Claim 7
Dependent Claim
33 words
Propeller blade according to claim 5, wherein the heating conductor is brazed to the outer shroud in sections and is curved inwardly at intermediate sections of the leading edge to form expansion bends.
Claim 8
Dependent Claim
16 words
Propeller blade according to claim 6, wherein the heating conductor is attached by heat conductor lugs.
Claim 9
Dependent Claim
20 words
Propeller blade according to claim 1, wherein the heating conductor is provided only along certain portions of the blade span.
Claim 10
Dependent Claim
24 words
Propeller blade according to claim 8, wherein the heating conductor is looped, with forward and back heating conductor lines extending in a parallel arrangement.
Claim 11
Dependent Claim
29 words
Propeller blade according to claim 1, wherein the outer shroud is attached to the plastic airfoil section of the blade by at least one of a bonding and riveting.
Claim 12
Dependent Claim
31 words
Propeller blade according to claim 1, wherein a joining edge between the outer shroud and the plastic airfoil section has at least one of a saw tooth and circular arc configuration.
Claim 13
Dependent Claim
23 words
Propeller blade according to claim 4, wherein the inner shroud extends from a blade root over only a portion of the blade span.
Claim 14
Dependent Claim
20 words
Propeller blade according to claim 1, the outer shroud is made of titanium, a titanium alloy or a maraging steel.
Claim 15
Dependent Claim
17 words
Propeller blade according to claim 1, wherein a blade tip is provided with a metallic protective cap.
Claim 16
Dependent Claim
30 words
Propeller blade according to claim 14, further comprising at least on lightning protection conductor which is connected from the protective cap to a blade root for electrical conduction and grounding.
Claim 17
Dependent Claim
17 words
Propeller blade according to claim 15, wherein the at least one lightning conductor comprises ribbon-shaped metal strips.
Claim 18
Dependent Claim
29 words
Propeller blade according to claim 15, wherein the at least one lightning conductor is routed on a pressure side of the airfoil and is masked with erosion inhibiting means.
Claim 19
Dependent Claim
24 words
Propeller blade according to claim 15, wherein the at least one lightning conductor exhibits a durability slightly inferior to that of the propeller blade.
Claim 20
Dependent Claim
24 words
Propeller blade according to claim 15, wherein the at least one lightning conductor comprises means for verifying the fatigue performance of the propeller blade.
Claim 21
Dependent Claim
50 words
Propeller blade according to claim 15, wherein the metallic protective cap is connected to the outer shroud and a metal shroud tube of a coaxial line having an inner conductor separated from the shroud tube by an insulating layer, the coaxially line comprising the heating conductor and the grounding means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-07-30 | 1994-01-29 | 1994-07-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-30 | 1998-01-29 | 1998-07-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-30 | 2002-01-29 | 2002-07-31 | $7700.00 | Window Closed / Lapsed |