GB2291844A

GB2291844A - Wheel rotating turbine means and a braking system for an aircraft undercarriage

Info

Publication number: GB2291844A
Application number: GB9415719A
Authority: GB
Inventors: Jonathan Taylor
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-08-03
Filing date: 1994-08-03
Publication date: 1996-02-07
Also published as: GB9415719D0

Abstract

The present invention relates to an air-driven turbine means having blades 17, 19 operable to rotate an aircraft undercarriage wheel 11 prior to landing. The turbine means is operable to direct air past braking means 14, 15 to cool the braking means. In a method of operation of the undercarriage of the aircraft during landing, the undercarriage is lowered prior to landing, one or more wheels of the undercarriage are rotated prior to landing of the aircraft, and braking of the undercarriage wheels is effected after landing. The blades of the turbine means are adjustable, to vary their angle of attack, by rotating a disc 22 relative to a support 21, the blades being pivotally attached to these components. <IMAGE>

Description

TURBINE MEANS, A BRAKING SYSTEM FOR AN AIRCRAFT AND A METHOD OF OPERATION OF UNDERCARRIAGE OF AN AIRCRAFT The present invention relates to turbine means operable to rotate an undercarriage wheel of an aircraft. The present invention also relates to a braking system incorporating the turbine means and to a method of operation of undercarriage of an aircraft during landing.

In the landing sequence of a conventional aircraft, the wheels of the undercarriage of the aircraft are lowered before landing and are stationary or virtually stationary when the wheels first touch the landing runway. The wheels are then caused to spin by frictional contact with the runway and the wheels are braked by braking means such as disc brakes in order to bring the aircraft to a halt on the runway.

The initial contact between the non-rotating wheels of the undercarriage and the runway causes considerable tyre wear because there is slip between the wheel and the runway until such time as the wheel is rotating at a speed to match the speed of the aircraft on the runway.

The present invention provides turbine means operable to rotate an undercarriage wheel of an aircraft which rotates the undercarriage wheel when driven by a flow of air past the aircraft.

The turbine means of the present invention operates to start an undercarriage wheel spinning before touch down to minimise tyre wear on touch down. The invention enables rotation of the undercarriage wheel without the need for the use of a combustion engine or electric motor.

It should be appreciated that the term wheel as used above and as used in the claim is meant to include a tyre and a wheel hub and the turbine means could be a distinct entity or could be formed integrally with the tyre, with the wheel hub or with both.

Preferably the turbine means comprises a plurality of vanes and adjustment means for adjusting the angle of attack of the vanes.

By varying the angle of attack of the vanes the speed of rotation of the undercarriage wheel can be controlled. Also the turbine means can be rendered inactive during take off.

Preferably the plurality of vanes in use extend radially in a plane parallel to the undercarriage wheel, each of the vanes being connected at a radially outward portion to a fixed member and each of the vanes being pivotally connected at a radially inward portion to a disc rotatable by adjustment means, rotation of the disc relative to the fixed member causing the radially inward portions of the vanes to rotate relative to the radially outward portions of the vanes to alter the angle of attack of the vanes.

In one preferred embodiment the adjustment means comprises an electric stepper motor connected to the rotatable disc.

In the second preferred embodiment the adjustment means comprises a hydraulic motor connected to the rotatable disc.

Preferably the turbine means is constructed to be connectable as a single unit to an undercarriage wheel. Whilst the turbine means could be formed integrally with an aircraft undercarriage wheel, construction of the turbine means in a single unit enables easy replacement of the turbine means and also enables the turbine means to be simply fixed to existing aircraft undercarriage wheels.

Preferably the turbine means comprises a plurality of vanes composed of an alloy of aluminium; for reasons of weight.

In a second aspect the present invention provides a braking system for an aircraft which comprises: braking means for braking an undercarriage wheel of the aircraft; and turbine means as described above connected to the undercarriage wheel; wherein the turbine means is operable to direct air past the braking means to cool the braking means.

The disc brakes of aircraft become very hot on landing and it is important to ensure a good flow of air passed disc brakes in order to cool the disc brakes. The present invention can enable cooling of the disc brakes by directing a flow of air through the turbine means on to the disc brakes. This minimises brake wear.

Preferably control means are provided for controlling the braking means and the control means is preferably operable to control the braking means to adjust the speed of rotation of the undercarriage wheel when the aircraft is airborne. The braking means can thus be used to provide a fine adjustment to the speed of rotation of the undercarriage wheel before landing.

Preferably the control means has means to sense failure of the adjustment means, the control means controlling the braking means to stop rotation of the undercarriage wheel when a failure is sensed.

In a third aspect the present invention provides a method of operation of undercarriage of an aircraft during landing, the method comprising the steps of: lowering the undercarriage prior to landing; rotating one or more wheels of the undercarriage prior to landing of the aircraft; and braking of the undercarriage wheels after landing.

As with the first aspect of the invention the third aspect of the invention has the advantage that one or more wheels of the undercarriage are rotated prior to landing of the aircraft and therefore the wear of the tyes of the wheels on landing is minimised, since there is no squeak" on touchdown because the wheels will be travelling at the right speed for the aircraft passing over the runway and will not have to receive rotation through frictional force interaction between the wheels and the runway.

Preferably the wheel or wheels of the undercarriage are rotated prior to landing by a flow of air past the aircraft prior to landing. Preferably turbine means of type described above is used to rotate the wheel or wheels.

Preferably the method of the invention includes the additional step of cooling the braking means by using the turbine means to direct a flow of air over the braking means.

Preferably the method includes the step of controlling an angle of attack of one or more vanes of the turbine means in order to vary the speed of rotation of the undercarriage wheel or wheels to bring the speed of rotation to the speed of rotation required for the wheel in order to match the aircraft speed on touchdown.

A preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a schematic part cross-sectional view of an aircraft wheel with turbine means according to the present invention, Figure 2 is a side elevational view of the aircraft wheel and braking system illustrated in figure 1.

Turning to figure 1 there can be seen an aircraft wheel 10 which comprises a tyre 11 mounted on the hub 12. The hub 12 is supported by an axle 13 which is part of the undercarriage assembly of an aircraft (only partly shown).

Attached to the inner side of the wheel hub 12 is a disc 14 of a disc brake assembly. The disc 14 can be acted upon by disc pad elements in calipers 15 which are fixed in position and are connected to the undercarriage assembly. All of this is standard in conventional aircraft.

The invention (in the preferred embodiment) lies in providing a turbine assembly 16 which is fixedly attached to the wheel hub 12.

A turbine assembly 16 comprises four vanes 17 to 20 each made of aluminium alloy, each hingedly connected at the radially outwardmost end to a support 21 and each hingedly connected at the innermost end to a disc support 22. The disc support 22 is connected to an electric motor 23 which is mounted on the support 21. The electric motor is preferably a stepper motor which can be used to rotate the disc support 22 relative to the support 21. The hinges connecting the vanes 17 to 20 to the support 21 and the disc support 22 are designed so that relative motion between the disc support 22 and the support 21 alters the angle of attack of the vanes 19 to 20.

The turbine assembly is provided as a single unit for easy attachment to the hub 12. Thus the turbine assembly 16 can be mounted to any existing wheel of an aircraft.

The turbine assembly 16 forms part of the braking system of the aircraft.

An aircraft fitted with turbine assembly 16 described above will in a normal fashion lower its undercarriage as it approaches a runway during landing. Once the undercarriage has been lowered, the turbine assembly 16 will be subject to a flow of air passing the aircraft and the turbine assembly 16 will be rotated by the airstream. The rotating turbine assembly 16 will then rotate the hub 12 and tyre 13 of the wheel 10.

The stepper motor 23 can be controlled to vary the angle of attack of the vanes 17 to 20 in order to control the speed of rotation of the wheel 10. The speed of rotation of the wheel 10 is controlled to match the speed of the aircraft on landing, so that there is no slip between the vehicle wheel 10 and the runway on landing.

If necessary the wheel 10 can be braked using the disc brake assembly comprising the disc 14 and calipers 15 in order to finely control the speed of rotation of the wheel 10. The braking of the wheel 10 will be controlled by an electronic controller 24 which receives signals from various sensors including a sensor 25 mounted on the hub 12 which senses the speed of rotation of the hub 12 and also a sensor 26 mounted on the support 21 which monitors the performance of the electric motor 23. The controller 24 controls a distributing valve 27 which controls the distribution of hydraulic pressure to the calipers 15 from a hydraulic pump (not shown).The electronic controller 24 will have an inbuilt failsafe system which will cause the calipers 14 and 15 to brake the vehicle wheel 10 if it is sensed that the electric motor 23 has ceased to function properly and therefore the vanes 17 to 20 may have the incorrect angle of attack.

After the aircraft has landed the electronic controller 24 will control the braking of the wheel 10 to rest.

As well as serving to cause rotation of the wheel 10 the turbine assembly 16 has a secondary function in cooling the disc 14 and disc pads of the calipers 15 during braking. The vanes 17 to 20 will be configured such that they direct a flow of air over the disc 14 and the disc pads of calipers 15,, the flow of air being indicated by arrows in figure 1. The hub 12 will have suitable perforations to allow flow of air through the hub 12, directed by the vanes 17 to 20. This would reduce brake wear. The angle of attack of the vanes 17 to 20 can be controlled after landing to maximise the cooling flow of air over the brakes during braking.

The angle of attack of the vanes 17 to 20 can be controlled during take off of the aircraft to minimise drag.

The advantages of the system described above are numerous. The system described will reduce the operating and maintenance costs of passengers and commercial airlines, because the system will reduce the wear of tyres and brakes and other anciliary equipment operating in the high temperature area of the wheel and hub assembly. A further advantage lies in reduced runway maintenance, that is resurfacing of runways. Since the tyres are at the correct speed of rotation before landing with reduced wheel squeak on touch down and reduced tyre wear, less friction burned rubber will be left on the runway on landing and therefore the runway will need repair less often and replacement less often.

The preferred embodiment of the invention has been described above, but the applicant envisages that the invention can be brought into effect in several other ways. For instance, the turbine means could be provided by vanes moulded integrally in the sidle walls of a tyre for an aircraft and/or by vanes formed integrally on an outwardly facing surface of a wheel hub for an aircraft. In such a case the applicant envisages that it might be preferable to provide some means for varying the airflow over the tyre and/or the wheel hub in order to control the speed of rotation of the tyre and the wheel hub.

Claims

1. Turbine means operable to rotate an undercarriage wheel of an aircraft which rotates the undercarriage wheel when driven by a flow of air past the aircraft.

2. Turbine means as claimed in Claim 1 comprising a plurality of vanes and adjustment means for adjusting the angle of attack of the vanes.

3. Turbine means as claimed in Claim 1 or Claim 2 comprising a plurality of vanes which in use extend radially in a plane parallel to the undercarriage wheel, each of the vanes being pivotally connected at a radially outward portion to a fixed member and each of the vanes being pivotally connected at a radially inward portion to a disc rotatable by adjustment means, rotation of the disc relative to the first member causing the radially inward portions of the vanes to rotate relative to the radially outerward portions of the vanes to alter the angle of attack of the vanes.

4. Turbine means as claimed in Claim 3 wherein the adjustment means comprises an electric stepper motor connected to the rotatable disc.

5. Turbine means as claimed in Claim 3 wherein the adjustment means comprises a hydraulic motor connected to the rotatable disc.

6. Turbine means as claimed in any one of the preceding claims constructed to be connectable as a single unit to an undercarriage wheel.

7. Turbine means as claimed in any one of the preceding claims comprising a plurality of vanes composed of an alloy of aluminium.

8. A braking system for an aircraft which comprises: braking means for braking an undercarriage wheel of the aircraft; and turbine means as claimed in any one of Claims 1 to 5 connected to the undercarriage wheel; wherein the turbine means is operable to direct air past the braking means to cool the braking means.

9. A braking system as claimed in Claim 8 which comprises control means for controlling the braking means which control means is operable to control the braking means to adjust the speed of rotation of the undercarriage wheel when the aircraft is landing.

10. A braking system as claimed in Claim 9 wherein the control means has sensor means for sensing failure of the adjustment means, the control means controlling the braking means to stop rotation of the undercarriage wheel when a failure is sensed.

11. A method of operation of undercarriage of an aircraft during landing, the method comprising the steps of: lowering the undercarriage prior to landing; rotating one or more wheels of the undercarriage prior to landing of the aircraft; and braking of the undercarriage wheels after landing.

12. A method as claimed in Claim 11 wherein the wheel or wheels are rotated prior to landing of the aircraft by turbine means driven by a flow of air past the aircraft prior to landing.

13. A method as claimed in Claim 12 wherein the wheel or wheels are rotated prior to landing by turbine means as claimed in any one of claims 1 to 7.

14. A method as claimed in Claim 13 which includes the step of controlling an angle of attack of one or more vanes of the turbine means in order to vary the speed of rotation of the undercarriage wheel or wheels to bring the speed of rotation to the speed pf rotation required for the wheel in order to match the aircraft speed on touchdown.

15. A method as claimed in any one of Claims 12 to 14 comprising the additional step of cooling the braking means by using the turbine means to direct a flow of air over the braking means.

16. Turbine means operable to rotate an undercarriage wheel of an aircraft substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

17. A braking system for an aircraft substantially as hereinbefore described with reference to and as shown in the accompanying drawings.