# US 4,394,109 A · Arrangement and equipment for the displacement of blades, particularly propeller blades

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- Number: US 4,394,109 A
- Document ID: US4394109A
- Status: Granted
- Kind: A
- Application number: 06/119,806
- Filed: 1980-02-08
- Granted: 1983-07-19
- Earliest claimed: 1980-02-08
- Assignees: Dornier GmbH
- Inventors: Donald Ritchie
- Web page: https://patentgrep.com/patent/US4394109A

## CPC

- B64C 11/28: Collapsible or foldable blades
- F01D 7/00: Rotors with blades adjustable in operation; Control thereof (for reversing F01D1/30)
- F02K 3/00: Plants including a gas turbine driving a compressor or a ducted fan
- F04D 29/323: {adjustable}
- F04D 29/362: {during rotation}
- F05D 2260/74: by turning around an axis perpendicular the rotor centre line
- F05D 2260/76: the adjusting mechanism using auxiliary power sources
- Y02T 50/60: Efficient propulsion technologies, e.g. for aircraft
- B64C: AEROPLANES; HELICOPTERS
- F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D)
- F02K: JET-PROPULSION PLANTS (features of jet-propulsion plants common to gas-turbine plants, air intakes or fuel supply control of air-breathing jet-propulsion plants F02C7/00, F02C9/00)
- F04D: NON-POSITIVE-DISPLACEMENT PUMPS (engine fuel-injection pumps F02M; ion pumps H01J41/12; electrodynamic pumps H02K44/02)
- F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

This invention relates to an improvement in equipment for the adjustment of blades, particularly propeller blades of fans, turbines, and the like, and especially for propulsion plants on aircraft, adapted to be selectively shut-off in a low-resistance position, the improvement comprising means whereby said blades are selectively foldable out of the operating position thereof about pivot axes transversely to their longitudinal axes, whereby said axes being tangential with respect to a common base circle are inclined with respect to the axis of rotation of said propeller blades in dependence upon the degree of twist of the blades, so that the blades in the folded-in position thereof are positioned next to each other jointly as parts of an imaginary cylindrical or conical envelope surface having a helical path with respect to the longitudinal envelope surface axis.

## Claims

### Claim 1

In equipment for the adjustment of rotor blades, particularly propeller blades of fans, turbines, and the like, and especially for propulsion plants on aircraft adapted to be selectively shut-off in a low-resistance position, said equipment including a rotor hub with blades pivotally mounted thereon, said blades (20) having a longitudinal axis (L.sub.A) and a twist (.DELTA..sub..theta.) about said axis (L.sub.A) between the chord line (S.sub.PF) at the blade root and the chord line (S.sub.PS) at the blade tip,
the improvement comprising means whereby said blades (20) are each selectively pivotal about pivot support means on the hub into an operational or a collapsed position,
said blades (20) when collapsed forming, by means of the position of pivot axes (33) of said pivot support means, helical cut-outs of a common cylindrical or conical envelope with the longitudinal axes (L.sub.A) extending at a slant imparted by the twist (.DELTA..sub..theta.) with respect to the longitudinal direction of said envelope,
the position of the pivot axes (33) at a common base circle being determined by the slant of the pivot axes (33) with respect to the plane of rotation (E--E) of said blades (20) and by the slant of the axes (33) with respect to the chord line (S.sub.PF) at the blade root.

### Claim 2 (depends on 1)

Equipment according to claim 1 in which for blades having a blade depth tapering from the blade root to the blade tip, the blades enclose an imaginary conical envelope surface in the folded-in position thereof, whereby the degree of tapering of the blades represents a function of the cone angle of the conical envelope surface.

### Claim 3 (depends on 1, 2)

Equipment according to claim 1 or claim 2 including setting ring means for pivoting the blades about the pivot axes, said setting ring means being relatively rotatable with respect to a fan impeller and including switching groove means extending in a helically inclined manner with respect to the circumferential direction for the engagement of trip cam means at the blades.

### Claim 4 (depends on 3)

Equipment according to claim 3 including selectively actuatable setting motor means for effecting relative rotation of the fan impeller and the setting ring.