WO1993004920A1

WO1993004920A1 - Rotating deicer sequence controller

Info

Publication number: WO1993004920A1
Application number: PCT/US1992/007486
Authority: WO
Inventors: Linda S. Boyd; Timothy M. Mcdonald; John F. Smith
Original assignee: United Technologies Corp
Current assignee: RTX Corp
Priority date: 1991-09-06
Filing date: 1992-09-04
Publication date: 1993-03-18
Anticipated expiration: 1994-03-06

Abstract

A deicing system for a propeller driven aircraft includes deicing apparatus such as electro-expulsive blankets disposed on the rotating propeller blades. The deicing apparatus receives electrical power from the stationary side (66) of the aircraft through an electrical power transfer interface such as a slip ring/brush block arrangement (72). The deicing apparatus receives electrical power in a timed sequence controlled by timer electronic circuitry (62) disposed on the rotating side of the aircraft.

Description

Rotating Deicer Sequence Controller

Technical Field

This invention relates to aircraft deicing systems, and more particularly to such systems having a controller disposed on a rotating propeller portion of a propeller-driven aircraft.

Background Art Propeller deicing systems comprise apparatus embodying various technologies such as pneumatic and electro-thermal. More recently, electro-expulsive, electro-impulsive, and eddy-current technologies have been proposed for use in propeller deicing. All of these systems either traditionally use or will use slip rings as the primary means of transmitting electrical power from the aircraft in a timed sequence to deicer blankets on the propeller blades and/or spinner. Current propeller deicing systems are controlled by a timer disposed on the stationary aircraft side. The timer signals when power is to be transmitted from the stationary side to the rotating side of the propeller system. Furthermore, the power is directed to different slip rings to energize certain blade deicers at a given time. One slip ring is required for each power transmission and one for electrical ground. Typically a pair of propeller blades or portions of the spinner are energized at a time. Thus, for a six-bladed propeller a total of four slip rings would be required: e.g., one for electrical ground and three for the blades and/or spinner. However, slip rings and the corresponding brushes are susceptible to many different wear and reliability problems. These problems are due to brush chatter, bounce, side wear hang-up, oil and brush dust contamination, arc-over, ring waviness, etc. Experience has shown that it is difficult to control all the wear and reliability causes systematically to produce a robust design.

Disclosure of Invention

Objects of the present invention include provision of apparatus on the rotating side of a propeller driven aircraft for controlling the sequencing of energization of propeller deicers.

Further objects include the reduction of the number of slip rings in transferring power from the stationary side to the rotating side of the aircraft. According to the present invention, a deicing system for a propeller driven aircraft includes deicing apparatus such as pneumatic, electro-thermal _r electro-impulsive, eddy-current, or electro-expulsive blankets disposed on the rotating propeller blades and/or spinner, the deicing apparatus receives electrical power from the stationary side of the aircraft through an electrical power transfer interface such as a slip ring/brush block arrangement, the deicing apparatus receives the electrical power in a timed sequence controlled by electronic circuitry disposed on the rotating side of the aircraft.

The present invention, as used in conjunction with electro-expulsive deicing technology, significantly reduces slip ring and brush block maintenance. Further, locating the timing sequence controller on the rotating side reduces the problem of unbalanced power draw and fluctuating demand over time from the aircraft generator. Either slip ring/brush systems or inductive coupling systems or other known systems may be used in conjunction with the present invention to transmit power to the rotating side.

Further, for slip ring/brush block systems, two slip rings may be used; one for power and one for ground, regardless of how many blades or deicer segments (blades and/or spinners) are involved. This reduces maintenance and increases reliability due to the elimination of one or more slip rings and the corresponding contacting brushes. For power transmission systems such as inductive couplers, it is also possible for both power and some portion of the controlling logic to be transmitted simultaneously. These and other objects, features and advantages of the present invention will become more apparent in light of the detailed description of an exemplary embodiment thereof, as illustrated in the accompanying drawings.

Brief Description of Drawings

Fig. 1 is a perspective view of an aircraft propeller system;

Fig. 2 is a cross sectional view of a single blade in the propeller of Fig. 1; Figs. 3(a) and 3(b) are detailed perspective views of a blade of Fig. 1 along with corresponding deicer segments; Fig. 4 is an electrical block diagram of apparatus for controlling the propeller deicing system illustrated in Figs. 1-3. ; and

Fig. 5 is a cross sectional view of the propeller system of Fig. 1.

Best Mode for Carrying Out the Invention

In Fig. 1 is illustrated a perspective view of an aircraft propeller system 10 having six (6) blades 12-22 emanating from a propeller hub 24 (not shown) covered by a spinner 26. The hub 24 is illustrated in more detail in Fig. 5. Each blade 12-22 is parenthetically numbered and has a deicer 28-38 attached to a leading edge thereof. The spinner 26 may also have a deicer 39 attached to a surface of the spinner. The deicer 28-39 may be of known technology, such as pneumatic, electro-thermal, electro-impulsive, eddy-current or electro-expulsive. For the broadest scope of the present invention, the type of deicer technology is irrelevant. However, in a preferred embodiment of the present invention, the deicer comprises the more modern electro-expulsive deicer ("EED") technology.

An example of a pneumatic deicing system is found in U.S. Patent No. 4,494,715 to eisend, Jr., assigned to the B.F. Goodrich Co., and which is hereby incorporated by reference. An example of an electro-impulsive deicing system ("EIDS") is that developed by Garrett Canada, a division of Allied-Signal Canada, Inc., Rexdale, Ontario, Canada. Alternatively, the EIDS may comprise that developed by Advance Concepts De-icing Company, San Diego, Calif., or developed by Rohr Industries, Inc., Chula Vista, Calif. An example of an eddy-current deicing system is that developed by Electroimpact, Inc., Seattle, Wash.

Examples of EED technology are found in U.S. Patent Nos. 4,894,569 and 4,982,121, both to Lardiere, Jr. et al.; U.S. Patent No. 4,875,644 to Adams et al. and assigned to the B.F. Goodrich Co.; and U.S. Patent No. 4,690,353 to Haslim. Each of these patents is hereby incorporated by reference. Described in each patent is deicer apparatus that is flexible and attached to a curved or flat air foil or other fixed aircraft member. When the air foil is exposed to a hostile environment, the deicer dilates in pulsating fashion to shatter and expel accumulated frangible material such as ice, mud or the like. Fig. 2 is a cross sectional view of a single blade 12-22 which illustrates the location of the deicers 28-38 on a blade leading edge. Since each blade deicer configuration is similar, only one blade and deicer is described herein. Each blade deicer is divided into, e.g., four (4) segments 40-46. In a similar fashion, the deicer 39 on the spinner 26 may also be divided into a number of segments (not shown) . As described in detail hereinafter, the blade deicer segments 40-46, along with the spinner deicer 39, are separately electrically energized in a timed sequence. Also indicated in Fig. 2 is the camber side 48 and the face side 50 of the blade 12-22.

In Figs. 3(a) and 3(b) are illustrated more detailed perspective views of a blade 12-22 and corresponding deicer segments 40-46. From these illustrations the height and width of the deicer segments in relation to the height of the blade can better be seen and appreciated. Referring to Fig. 4, there illustrated is an electrical block diagram of apparatus 60 for controlling the propeller deicing system of Figs. 1-3. The apparatus 60 is similar to that illustrated and described in the aforementioned U.S. Patent No. 4,690,353 to Haslim, particularly Fig. 1 and the accompanying text therein.

The aircraft has a rotating deicer sequence controller 62 disposed on a rotating propeller portion 64 of the aircraft in accordance with the present invention. One or more electrical power and ground signals are transmitted from an aircraft power supply 65 located on the stationary (i.e., non-rotating) side 66 of the aircraft. The power and ground signals are fed on signal lines 68,70, respectively, out to a slip ring 72 and brush block 74 arrangement located at the propeller on the engine nacelle. The slip ring/brush block scheme is a well known exemplary method of transmitting electrical power across a stationary/rotating mechanical interface.

It is to be understood, however, that for the broadest scope of the present invention, the method of transmitting electrical power from the stationary side to the rotating propeller portion of the aircraft is irrelevant. Thus, for example, a known inductive coupling method may be used instead of the slip ring/brush block scheme. However, the present invention has the greatest potential for benefit in a slip ring/brush block arrangement.

The electrical power and ground on the rotating propeller portion are fed to a high voltage power supply 80. As illustrated, the high voltage power supply 80 is on the rotating propeller portion of the aircraft. However, it is tb be understood that the supply 80 may, if desired, be located on the stationary side of the aircraft. The supply provides a high voltage on a line 82 to a first terminal 84 of each of a number (N) of single-pole, double-throw (SPDT) switches 86. A second terminal 88 of each switch 86 connects to a segment 40-46 of a corresponding deicer blanket or to the spinner deicer 39. The arm 90 of each switch connects at an end to an associated power storage unit 92, typically a capacitor. The use of capacitors 92 for energy storage with EED technology significantly reduces the power required from the aircraft electrical system compared to that required for electro-thermal deicers. When any one of the arms 90 is connected to the corresponding first terminal 84 of any switch 86, then high voltage on the line 82 is fed to the associated power storage unit 92 to charge that unit. Conversely, when any one of the arms is connected to the corresponding second terminal 88 of any switch, then the energy stored in the associated power storage unit is fed to the corresponding deicer segment 40-46 or spinner deicer 39.

The position of each arm is individually controlled by the sequence controller 62 through a signal on a line 94. In this way the controller schedules the delivery of electrical power in an orderly sequence to the segments 40-46 or spinner deicer 39. It is to be understood that each SPDT switch 86 is independently controlled by the signal on the line 94. Thus, this signal may in reality represent a plurality of individual signals on a corresponding plurality of signal lines.

The details of the sequence controller 62 form no part of the present invention. The sequence controller is well known and may be similar to that described in the aforementioned U.S. Patent No. 4,690,353. to Haslim et al., which has heretofore been incorporated by reference. As an alternative, the sequence controller may be that supplied by ICE Corp., Manhattan, Kansas.

Regardless of the detailed form of the sequence controller, its operation is such that the deicer segment 40-46 or spinner deicer 39 to be energized is selected and activated for a period of time. The deicer is then deactivated and the system may delay, if desired, for some time before selecting and activating the next segment in the desired sequence. This procedure is repeated until all or some portion of the segments have been activated and deicing of the propeller blades and/or spinner is complete.

In practice, for a six-bladed propeller, one segment 40-46 on each of two blades 12-22 or spinner may, if desired, be simultaneously controlled. However, the specific number of segments and optimum sequencing will vary depending on the specific propeller deicing system design.

The power sequencing for an EED is more complex than for other types of deicing systems. The minimum time between deicer energization is a function of how long the capacitors take to recharge. The blade or spinner area that can be deiced is also a function of capacitance, where larger capacitors are needed to deice larger areas. Based on the relationship between capacitor size and the corresponding area that can be deiced, each blade deicer in Fig. 2 consists of four segments 40-46: two on the camber side 48 and two on the face side 50. To provide symmetry of propeller ice shedding, alternate blades 12-22 on a propeller may be energized simultaneously. Thus, a single firing may deice one segment on each of three blades. Each segment is fired, e.g., twice per minute.

The sequence controller 62 may select a repeatable pattern of segment energization, or may vary the number or timing of the sequence. A variable sequence may be used to optimize ice removal by using additional inputs, such as temperature or ice presence, to increase or decrease the frequency of energizing particular segments. The variable sequence may also increase the life of the deicer to be energized.

In Fig. 5 is illustrated a cross sectional view of the propeller system of Fig. 1. Each propeller blade 12-22 emanates from the rotating propeller hub 24 covered by the spinner 26. The deicer 28-38 is attached to a leading edge of the blade. Also illustrated is a brush block 74 and associated slip rings 72, along with the spinner deicer 39. In accordance with the present invention, the electronic circuitry of Fig. 4 for controlling deicer segment energization may be located at various places on the rotating side of the propeller. The circuitry is preferably enclosed in a housing 100 which is able to withstand the normally harsh environmental conditions. The portion of the circuitry which is typically located within the housing is within the dotted lines of Fig. 4.

In Fig. 5 the housing 100 may be located at the front or side of the modular actuator assembly 102. Alternatively, the housing may be mounted to the hub 24. It is to be understood that these locations are purely exemplary; any suitable mounting location on the rotating side may be used, if desired, in accordance with the present^' invention. With the housing mounted to the hub, also illustrated in Fig. 5 is the location of necessary wiring between the housing and the slip ring/brush block arrangement, and also between the housing and the deicer on the blades and spinner.

The present invention moves the unit which controls the energy received at the blade or spinner from the stationary side to the rotating side of a propeller deicing system. The final selection of deicer segment(s) to receive energy is on the rotating side of the propeller system. This reduces the unbalanced power draw and periodic fluctuations in power demand prevalent in the prior art when propeller deicing is required. For slip ring/brush block systems, the present invention also reduces the number of required slip rings to, e.g., two, regardless of how many deicer segments are energized simultaneously. The use of two rings along with lower current requirements translates into smaller, lighter components including slip rings, mounting block, connectors and harness wiring. Further, the potential for electrical arcing problems is reduced with two slip rings. For systems using either inductive couplers or slip rings and brushes for power transmission, the transmitted power can be stored in capacitors on the rotating side until the timing sequence controller directs the energy.

Although the invention has been shown and described with respect to a best mode embodiment thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions, and additions in the form and detail thereof may be made therein without departing from the spirit and scope of the^'invention.

Claims

1. An electro-expulsive deicing system for a propeller-driven aircraft, comprising: electro-expulsive deicing means, disposed on one or more normally rotatable blades or on a spinner of a propeller on the propeller-driven aircraft; power means, disposed on a stationary, non-rotatable portion of the propeller-driven aircraft, for providing one or more electrical power signals; and sequence controller means, disposed on a normally rotatable propeller portion of the propeller-driven aircraft and responsive to said one or more power signals, for providing one or more deicing control signals, said electro-expulsive deicing means responsive to said deicing control signals for deicing the one or more normally rotatable blades of the propeller in a predetermined sequence.

2. The system of claim 1, further comprising: power transfer means, responsive to said one or more power signals, for transferring said quantity of electrical power, as indicated within said one or more power signals, from said stationary, non-rotatable portion to said rotatable propeller portion of the propeller-driven aircraft, and for providing one or more electrical power signals on said rotatable propeller portion of the propeller-driven aircraft, said sequence controller means being responsive to said one or more electrical power signals on said rotatable propeller portion of the propeller-driven aircraft for providing said one or more deicing control signals.

3. The system of claim 2, wherein said power transfer means comprises slip ring and brush block means.

4. The system of claim 2, wherein said power transfer means comprises inductive coupling means.

6. The system of claim 1, wherein said sequence controller means is disposed on a hub of the propeller driven aircraft.

6. The system of claim 1, wherein said sequence controller means is disposed on a modular actuator assembly of the propeller driven aircraft.

7. The system of claim 1, wherein said electro-expulsive deicing means comprises one or more individual deicing segments, each of said one or more deicing segments disposed on a leading edge of said one or more normally rotatable propeller blades and being responsive to said one or more deicing signals.

8. An electro-expulsive deicing system for a propeller-driven aircraft, comprising: electro-expulsive deicing means, disposed on a spinner of a propeller on the propeller-driven aircraft; power means, disposed on a stationary, non-rotatable portion of the propeller-driven aircraft, for providing one or more electrical power signals; and sequence controller means, disposed on a normally rotatable propeller portion of the propeller-driven aircraft and responsive to said one or more power signals, for providing one or more deicing control signals, said electro-expulsive deicing means responsive to said deicing control signals for deicing the spinner of the propeller in a predetermined sequence.

9. The system of claim 8, further comprising: power transfer means, responsive to said one or more power signals, for transferring said quantity of electrical power, as indicated within said one or more power signals, from said stationary, non-rotatable portion to said rotatable spinner portion of the propeller-driven aircraft, and for providing one or more electrical power signals on said rotatable spinner portion of the propeller-driven aircraft, said sequence controller means being responsive to said one or more electrical power signals on said rotatable spinner portion of the propeller-driven aircraft for providing said one or more deicing control signals.

10. The system of claim 9, wherein said power transfer means comprises slip ring and brush block means.

11. The system of claim 9, wherein said power transfer means comprises inductive coupling means.

12. The system of claim 8, wherein said sequence controller means is disposed on a hub of the propeller driven aircraft.

13. The system of claim 8, wherein said sequence controller means is disposed on a modular actuator assembly of the propeller driven aircraft.

14. The system of claim 8, wherein said electro-expulsive deicing means comprises one or more individual deicing segments, each of said one or more deicing segments being disposed on said spinner and being responsive to said one or more deicing signals.