Tachometer systems and methods of determining the rotation speed of a wheel of a landing gear of an aircraft

Patent metadata

Field	Value
Publication number	US-10048287-B2
Application number	US-201615152381-A
Country	US
Kind code	B2
Filing date	May 11, 2016
Priority date	May 11, 2015
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

A tachometer system for an aircraft landing gear. The tachometer system includes a tachometer arranged to generate a variable voltage signal in response to the rotation of a wheel of the aircraft landing gear, and a processing system arranged to output a speed signal indicative of the rotation speed of the wheel of the aircraft landing gear. The speed signal is determined from the variable voltage signal from the tachometer using a set of determined parameters. The determined parameters of the processing system are determined from the voltage levels of the variable voltage signal.

First claim

The invention is:

1. A tachometer system for an aircraft landing gear comprising:
a tachometer configured to generate a variable voltage signal in response to the rotation of a wheel of the aircraft landing gear; and
a processing system configured to output a speed signal indicative of the rotation speed of the wheel of the aircraft landing gear, the speed signal being determined from the variable voltage signal from the tachometer using a set of determined parameters, and the processing system including a dynamic relay arranged to receive the variable voltage signal and output a stepped signal that is at a first level when the variable voltage signal is above a first determined threshold and is at a second level when the variable voltage signal is below a second determined threshold;
wherein the determined parameters of the processing system are determined from the voltage levels of the variable voltage signal;
wherein the processing system is arranged to:
determine the speed signal by determining when the stepped signal transitions between one of the first and second level and the other of the first and second level;
determine an acceptable range of rotation speeds based on maximum and/or minimum voltage level(s) of the variable voltage signal occurring during prior cycles of the variable voltage signal;
output the speed signal while maximum and/or minimum voltage level(s) of a variable voltage signal of a current cycle of the variable voltage system is/are in the acceptable range, and
output a modified speed signal while the maximum and/or minimum voltage level(s) of the variable voltage signal of the current cycle is/are outside of the acceptable range.

2. The tachometer system as claimed in claim 1 , wherein the determined parameters are determined from the maximum and minimum voltage levels of the variable voltage signal.

3. The tachometer system as claimed in claim 1 , wherein the processing system is arranged to ignore a transition of the stepped signal when the rotation speed indicated by the stepped signal is above the range of rotation speeds determined from the voltage levels of the variable voltage signal.

4. The tachometer system as claimed in claim 1 , wherein the processing system is arranged to assume an additional transition of the stepped signal has occurred when the rotation speed indicated by the stepped signal is below the range of rotation speeds determined from the voltage levels of the variable voltage signal.

5. The tachometer system as claimed in claim 1 , wherein the processing system is arranged to determine the level of the speed signal based upon the time taken between the preceding transitions of the stepped signal.

6. The tachometer system as claimed in claim 1 , wherein the processing system is arranged to output, when the stepped signal transitions, a modified speed signal determined from the rotation speed indicated by a set of preceding stepped signals.

7. An aircraft comprising a tachometer system as claimed in claim 1 , wherein the aircraft includes a display in a cockpit and the display presents an alphanumeric graphical representation of a current ground speed of the aircraft and the current ground speed is determined based on a current value of the speed signal.

8. The tachometer system of claim 1 wherein the prior cycles are cycles of the variable voltage signal immediately preceding the current cycle.

9. The tachometer system of claim 1 wherein the prior cycles are at least five cycles of the variable voltage signal immediately preceding the current cycle.

10. A method of determining the rotation speed of a wheel of a landing gear of an aircraft, wherein the aircraft comprises a tachometer arranged to generate a variable voltage signal in response to the rotation of the wheel of the aircraft landing gear, the method comprising:
determining a set of parameters from the voltage levels of the variable voltage signal;
generating a speed signal indicative of the rotation speed of the wheel of the aircraft landing gear from the variable voltage signal using the set of determined parameters by:
generating a stepped signal from the variable voltage signal by, wherein the stepped signal is at a first level when the variable voltage signal is above a first determined threshold, and at a second level when the variable voltage signal is below a second determined threshold, and wherein the speed signal is determined from the stepped signal by determining when the stepped signal transitions between one of the first and second level and the other of the first and second level;
determining an acceptable range of rotation speeds based on maximum and/or minimum voltage level(s) of the variable voltage signal occurring during prior cycles of the variable voltage signal;
outputting the speed signal while maximum and/or minimum voltage level(s) of a variable voltage signal of a current cycle of the variable voltage system is/are in the acceptable range, and
outputting a modified speed signal while the maximum and/or minimum voltage level(s) of the variable voltage signal of the current cycle is/are outside of the acceptable range.

11. The method as claimed in claim 10 , wherein the determined parameters are determined from the maximum and minimum voltage levels of the variable voltage signal.

12. The method as claimed in claim 10 , wherein the step of generating the speed signal comprises the step of ignoring a transition of the stepped signal when the rotation speed indicated by the stepped signal is above the range of rotation speeds determined from the voltage levels of the variable voltage signal.

13. The method as claimed in claim 10 , wherein the step of generating the speed signal comprises the step of assuming an additional transition of the stepped signal has occurred when the rotation speed indicated by the stepped signal is below the range of rotation speeds determined from the voltage levels of the variable voltage signal.

14. The method as claimed in claim 10 , wherein the step of generating the speed signal comprises the step of determining the level of the speed signal based upon the time taken between the preceding transitions of the stepped signal.

15. The method as claimed in claim 10 , wherein the wherein the step of generating the speed signal comprises the step of when the stepped signal transitions, determining a modified speed signal from the rotation speed indicated by a set of preceding stepped signals.

16. The method of claim 10 further comprising displaying a graphical representation of a current ground speed of the aircraft on a display in a cockpit of the aircraft, wherein the current ground speed of the aircraft is determined based on the speed signal.

17. The method of claim 10 wherein the prior cycles include cycles of the variable voltage signal immediately preceding the current cycle.

18. The method of claim 10 wherein the prior cycles are at least five cycles of the variable voltage signal immediately preceding the current cycle.

Assignees

• Airbus Operations Ltd

Inventors

• Bidmead Ashley

Classifications

• G01P3/46

  by measuring amplitude of generated current or voltage {(in general G01R19/00)} · CPC title

• B64C25/36

  Arrangements or adaptations of wheels, tyres or axles in general · CPC title

• G01P3/465 Primary

  by using dynamo-electro tachometers or electric generator · CPC title

• G01P3/488

  delivered by variable reluctance detectors · CPC title

• G01P3/489

  Digital circuits therefor · CPC title