JPS60244698A - Anti-icing system of aircraft propeller - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] Technical Field The present invention relates to an aircraft propeller. ``i Ice protection system, more specifically, relates to the 1F ice protection system in which the electric heater is protected from burning out.

The deleterious effects of icing on aircraft propellers are well known, and heating of propellers with electric heaters has long been practiced to minimize these effects. Typically,
Such heaters are embedded in the propeller blades, spinners and rear body, and are energized either manually by the aircraft operator or automatically by the icing sensor 9.

The heat output of a propeller heater must be large enough to melt ice or prevent icing under normal operating conditions when the air flow cooling the heater is present on the propeller surface. To compensate, the heat output of the heater must be significantly greater than that required for anti-icing and de-icing in the absence of such air flow. Therefore, when there is little or no air flow on the C1 propeller surface,
For example, if a heater is unintentionally energized during maintenance on the ground, it is likely that the heater will burn out.

Known measures to prevent heater burnout when the aircraft is on the ground include providing a switch that isolates the propeller heater from its power source when the weight of the aircraft is supported by its landing gear. However, when the aircraft is being jacked up for maintenance and the landing gear is not supporting the weight of the aircraft, this switch will not cause false power to the heater.

Other known solutions for energizing the propeller heater only under conditions of propeller rotation include energizing the heater by means of a small generator carried within the propeller and mechanically coupled to the propeller, thereby This includes preventing power from being supplied to the propeller when the propeller is not rotating. This measure prevents accidental burnout of the heater on the ground when the propeller is not rotating (although such auxiliary generator equipment adds significantly to the weight, complexity, and cost of the propeller system). Listen.

DISCLOSURE OF THE INVENTION It is an object of the present invention to provide a method that is simple and independent of the relationship between C1 aircraft lift and landing gear length under conditions of insufficient airflow over the propeller surface. The purpose is to prevent burnout of the propeller heater.

According to the present invention, a pulsed signal synchronized with the rotation of the propeller is used as an indication of the propeller rotation speed, and when the rotation speed of the propeller falls below a predetermined value, the propeller is cut off from the power source. In a preferred embodiment, the pulsed signal includes a pulsed voltage produced by induction on a fixed coil inside the propeller by a permanent magnet rotating with the propeller, and the voltage pulse produced by the induction is used as an input signal to a signal processing circuit. This signal processing circuit compares the frequency of the input signal with a reference frequency and provides an output signal i to the control circuit indicating the load between both signals. If the frequency of rotation is 1) lower than the reference frequency, it indicates that the propeller is operating under conditions where its surface is sufficiently cooled by the air flow, and the signal processing circuit The output signal of connects the propeller heater to the power source through the control circuit.If the frequency of rotation is Ji,
If the il (frequency is lower than The propeller heater is isolated from the power source via a circuit to prevent burnout of the heater.Such propeller heater protection is accomplished within known propeller heating and control systems by simply adding signal processing circuitry to the system. The signal processing circuit can be easily and inexpensively added by changing the solid stay timer used to periodically energize the propeller and motor under normal operating conditions. obtain.

DESCRIPTION OF THE PREFERRED EMBODIMENTS S AND INDUSTRIAL APPLICATIONS Referring to the drawings, an electrically heated aircraft propeller 5 is electrically connected to a power source 10 by a normally open switch 15 and a brushed slip ring assembly 20. connected. When anti-icing IF on the 71:I bellow surface is required, the switch control means 25 closes the switch 15 and the 71N bellows heater is powered by the power source 10. Signal processor + u that responds to the pulsed electrical signal from the
30 provides a horn signal to the switch control means 25 whereby the switch 15 is activated when the propeller speed is less than that required to produce sufficient airflow over the propeller surface to prevent heater burnout. open.

The propeller 5 includes a plurality of blades 35, each of which has an embedded electric heater. One of the electric heaters is designated by reference numeral 40 (tb).

The propeller blades extend from a hub covered by an aerodynamic spinner 45 that rotates with it. The spinner is provided with a heater 50 at its tip and one or more heaters 55 are attached to its body. It is provided inside.9
In Type 0, icing on the non-rotating rear body 60 is prevented by a resistance heater 65 embedded therein. Non-rotating coil 7 wound around ferromagnetic core 75
0 is placed inside the subino.
) passes through the coil to induce a pulsed electric signal in the coil, and this signal is sent to the signal processing circuit 30 through the conductor 85. .

The propeller heater has a conductor wire of 90.9! J and 100 are connected to J: rebrush to slip ring group)'1 body 90. The assembly 20 includes slip rings 105, 110 electrically contacted by brushes 120, 125) and 130.
and ]15. The switch 15 is connected to a switch 15 driven by a switch control means 25, which will be explained in more detail later.
35, 140 & 145 to power source 10. Switch 150/160 is 1/9 in the aircraft cockpit.
The main switch for the propeller heater is driven by the operator.

The switches 1 are connected to a timer (sequencer) 175 by conductors 180, 185 and 190, and a solenoid 161 is energized by a manual timing signal.
, 16, 5 and 170. timer 175
41 timing and sequencing circuit 200 and this time f
switch circuit 20 including electronic switches 206, 207 and 209 that open and close in response to input signals to fl 200;
Contains rito.

This timer includes a conductor 21 with a normally open switch 215.
2 by a low voltage power supply 210. Switch 215 is closed by solenoid 220 which receives an input signal from signal processing circuit 30 to which it is connected through conductor 225. The signal processing circuit 30 includes a frequency counter 230 which receives a bounce signal as an input signal from the coil 70 via a conductor 85. An output signal from a frequency counter 230 indicating the rotational speed of the rotor is applied via a conductor 240 to a summing point or difference forming circuit 235. The summing point 235 forms the difference between the frequency of the output signal from the frequency counter and a reference frequency which indicates the lowest propeller speed at which airflow over the propeller surface minimizes the risk of heater burnout. This difference is passed through conductor 247 to C digital memory or analog function generator 2/15.
given to.

As shown in the drawing, Mess 2/I5 provides a positive output signal through 41 PA 22 :> to solenoid 220 to drive switch 2215 when the electrical difference is positive. If the frequency counter output signal is less than the target frequency, the angular input signal is provided by 5235 to memory 245, thereby providing a zero output signal from memory to solenoid actuator 220.

Under popular conditions when there is a possibility of ice forming on the propeller while operating the aircraft, the operator of the aircraft with the propeller 5 closes switches 150 to 160 and switches 15 to
give. The opening of the switch 15 by the power of the trenoids 16'1 to 170 connects the heaters 40, 50, 55 and
Connect 5 electrically. As known to the Department,
Anti-icing (continuous energization of the heater to prevent ice from accreting on the propeller surface) and de-icing (periodic energization of the heater to loosen the 44 necks of ice on the propeller surface and throw them away with centrifugal horns) is also used. Su1! Typically, the tip and aft body heaters are energized continuously in an anti-icing mode, while the spinner and vane heaters are energized periodically in a de-icing mode. The periodic energization of the heaters is controlled by a timer and switching circuit 200, respectively. timer 2
60 periodically switches switches 207 and 209 associated with heaters 40 and 55 for deicing purposes. tl is programmed to close, but on the other hand, switch 206 is continuously kept closed (by keeping heaters 50 and 65 continuously energized).
The power supply is maintained by opening the switch 215.

When the propeller is not rotating, there is no output from the coil 70, the output frequency of the frequency counter 230 is zero, and the sum of 1111λ and the output of one point 235) is negative. As a result, the output of memory 245 is zero, solenoid 220 is not energized, and switch 215 is open, thereby disconnecting tie 7175 G;L power supply 210. Its bundling, timing and switch circuits are not supplied with power 1F, and the power switch 206-.
Listen to 209. Therefore, the solenoid actuator 161-1
70 i;L (1 not activated, switch 11) is heard, and the heater is turned off from the power source 10 by the switch 11.
l'LU, minimizing the risk of accidental heater burnout even if the cockpit switch is inadvertently closed. Whenever the frequency of the coil output signal is lower than the reference frequency, the output of the main switch 245 is zero, and the switches 215 and 206 to 209 are open, so the closing of the switch 15 and the energization of the propeller heater are prevented. Ru. When the frequency of the pulsed signal from the coil 70 is higher than the reference frequency J: normal propeller operation is indicated, and the output of the memory 245 energizes the solenoid actuator 120.
Close the switch 215 and connect the timing circuit 200 and the switching circuit 2055 (=J).
Solenoids 161 to 170 are energized and switch 1 is activated.
5 is closed, the propeller heater is switched to the cockpit switch 15.
Manually close 0 to 160 (energized by 2).

According to the present invention, accidental burnout of a bellows heater can be effectively minimized without the increased cost, complexity, and weight associated with the addition of a generator to energize the heater. Furthermore, the heater protection provided by the present invention is independent of the relationship between aircraft weight and landing gear length. The invention can be implemented in existing propeller heater systems by simply adding an inexpensive, compact, solid-state signal processing circuit to timer 175. Further, the utilization of the output from the coil 70 in synchronization with the propeller increases the efficiency of the system according to the present invention.

Although the present invention has been described in detail with respect to specific embodiments above, the present invention is not limited thereto.
It will be apparent to those skilled in the art that various embodiments are possible within the scope of the invention. For example, while we have described a single propeller with a particular heater arrangement,
It will be appreciated that the present invention may also be used with multiple propellers with any desired heater arrangement. Furthermore, the propeller rotational speed is shown in the form of an IJ pulse (although it has been described as using an Il and a permanent magnet T1 to generate rf f3, other means of balance are possible). rotation and F6J
It will be appreciated that the l1lJ signal can be used for the generation of signal V3.

Similarly, although the explanation has been made assuming that a separate frequency counter, summing point U, and memory are used, when the frequency of rotation is lower than the base i1, it is impossible to energize the zo[1 perahita circuit. It will be understood that various components of the Sage with equivalent functions may be used. These and other modifications are intended to be within the scope of the invention as claimed.

'1. Drawing) The explanatory drawing is a type I diagram of a propeller icing protection system protected against heater burnout according to the present invention.

5... Propeller, 10... Power source, 15... Normally closed switch, 29... Brush slip ring assembly.

5... Switch control means, 30... Signal processing circuit,
35...Propeller blade, 40...Heater, 45...
・Spina.

50.55... Heater, 60... Rear body, 65
...Heater, 70...Non-rotating"il, 75...Ferromagnetic iron core.

80...Permanent magnet, 10; 110.115...
Slip ring, 120.12, 1330... brush.

150.155.160...Switch, 161.16
5.170... So 1 made, 175... Tie, Ma, 200... Timing and sequence ring circuit, 2
05...Switching circuit, 206.207.209
...Switch, 210...Low voltage power supply, 215...
・Normally closed switch, 220...Solenoid 1-23
0...Frequency counter, 235...Addition point,
245...Memory Patent Applicant United Technologies Corporation Patent Attorney Masaru Akira Continued from page 1 Inventor Peter John Vuozola Windsor Electronics, Connecticut, United States; Taft Lane 180

Claims (1)

[Claims] At least one electric heater j! I! In an aircraft propeller icing prevention system, the electric heater is connected to an electric power source, and also includes signal means for generating a pulsed electric signal indicative of the rotational speed of the electric heater. a switch for connecting; and control means responsive to the pulsed electrical signal to drive the support switch to disconnect the electric heater from the power source when the frequency of the pulsed electrical signal is lower than a reference frequency. and thereby preventing burnout of the electric heater due to energization of the electric heater when the four-speed claw of the propeller is lower than a predetermined value corresponding to the reference frequency. 11 systems to prevent icing on aircraft propellers.