Apparatus for causing an aircraft wheel to rotate

Abstract: The invention provides apparatus for causing an aircraft wheel to rotate, comprising at least one nozzle or vent (126, 156, 164, 178, 184) centred on the axle of the wheel and arranged to expel air at least partially circumferentially with respect to said circle, and air supply means for providing air to the or each nozzle or vent (126, 156, 164, 178, 184) for expulsion therethrough, the air supply means comprising a compressed air source and an air supply passage connecting the compressed air source to the or each nozzle or vent (126, 156, 164, 178, 184), wherein the or each nozzle or vent (126, 156, 164, 178, 184) is rotatable with the wheel such that expulsion of the air through the or each nozzle or vent (126, 156, 164, 178, 184) causes rotation of the wheel.

Description: The invention relates to apparatus for causing an aircraft wheel to rotate. It is well known that aircraft tyres need to be replaced at frequent intervals as a result of wear sustained on landing. It is also recognised that this wear can be reduced by causing the wheels of an aircraft to rotate, immediately prior to landing, at or near the landing speed of the aircraft. Many attempts to achieve such wheel rotation have been proposed but one of the major difficulties has been devising a wheel or attachment which produces sufficient turning moment during landing but which does not create problematic drag during take-off. One way to increase the turning moment during landing without increasing the drag during take-off is to provide rotating means which are movable between a deployed position and a retracted position. In the deployed position, used during landing, the rotating means are positioned so as to maximise the turning moment applied to the wheel. Increased drag is not problematic during landing; indeed, it can be beneficial. In the retracted position, used during take-off, drag is minimised along with the turning moment which is not required on take-off. Examples of prior art arrangements which utilise this type of retractable system are illustrated in US patents Nos. 2 666 604 and 4 732 350. However, because of the need to retract the scoops and vanes, it will be noted that the total area of the scoops and vanes exposed to the airflow is relatively small. Further examples of prior art, namely US 3 026 069, US 4 385 739, FR-A-912 891 and US 2 414 849, illustrate methods of causing an aircraft wheel to rotate by directing a flow of air, taken either from a compressed air source or from an engine, onto vanes located on the wheel. However, the presence of the nozzle which directs the flow of air onto the vanes is cumbersome and increases the drag on take-off. It is an object of the invention to provide an alternative arrangement which does not itself create significant drag on take-off. The invention provides an aircraft wheel including apparatus for causing an aircraft wheel to rotate as set out in Claim 1. Advantageous features are set out in the subsidiary claims. The invention also provides an aircraft as set out in Claim 9. The invention will now be described with reference to the accompanying drawings wherein: Fig. 1 is a plan view of a wheel incorporating apparatus according to a first embodiment of the invention; Fig. 2 is a cross-sectional view taken along line II-II of Fig. 1; Fig. 3 is a plan view of a part of apparatus according to a second embodiment of the invention; and Figs. 4 and 5 illustrate further embodiments of the invention. An embodiment of the invention is illustrated in Fig. 1. In general, the Figures illustrate the apparatus 100 in combination with a wheel 102, consisting of a hub 104 and a rim 106 on which a pneumatic tyre 108 is mounted, the wheel hub 104 being mounted in a conventional manner on an axle 110 by way of bearings 112. Essentially, in each embodiment, a compressed air chamber or passageway 150 is provided. Looking firstly at Figs. 1 and 2, the chamber is bounded on one side by an upper cover 152 and by a lower passageway 154 on the other. At the radial extremes of the compressed air chamber 150, vents 156 are provided through which the compressed air introduced into the chamber 150 can escape. These vents 156 are arranged such that a tangential element of force is created, thereby ensuring that the wheel is rotated as compressed air passes through the vents 156. Arrangements different from that shown in Fig. 2 are, of course, possible and equally effective. The lower passageways 154 illustrated in Fig. 2 are arranged to pass through the wheel rim into the pneumatic tyre cavity before emerging again on the side of the tyre remote from the cover 152. This is done to avoid interference with the braking system. It also reduces the risk of an imbalance of the wheel occurring. Turning now to the embodiments shown in Figs. 3 to 5, it will be appreciated that Figs. 4 and 5 each illustrate two various alternative arrangements. However, these embodiments are all based on the principle of the compressed air chamber 150 as illustrated in Figs. 1 and 2. Fig. 3 is a plan view of the air chamber illustrated on the left hand side of Fig. 4. In this embodiment, compressed air is introduced to the chamber 150 via the axle. The compressed air passes along the radial passages 158 and then along the generally tangential passages 160 before exiting to atmosphere. The tangential arrangement of the passages 160 causes the wheel to which the chamber 150 is attached to rotate as compressed air is expelled. It is particularly advantageous if the chamber 150 described above is used in conjunction with a wheel having two adjacent tyres attached to a single wheel rim. The chamber 150 can be arranged so that the generally tangential passages 160 open in the area immediately between the two tyres. This reduces the risk of the passages 160 becoming inadvertently blocked by foreign matter, although care must be taken to ensure that the passages 160 do not extend radially to such an extent that they may become damaged during landing. A similar but alternative arrangement is illustrated on the right hand side of Fig. 4. The only difference between this arrangement and that described above is the fact that the passages 162 extend substantially radially with respect to the wheel rim and incorporate tangential vents 164 at their distal ends. Again, the vents are effectively shielded from damage by the dual tyres and are positioned sufficiently near to the axle to avoid damage on landing. Fig. 5 illustrates two further variations on the same theme. In the left hand side of Fig. 5, the radially outward area of the chamber 150 is essentially incorporated into the tyre. The tyre 170 is mounted on a single wheel rim but incorporates two separate tubes 172, 174. The walls of the tubes 172, 174 also form the walls of the radial passage 176 which is located between the tubes 172, 174. A tangential vent 178 is arranged in the end of the passage 176. When compressed air introduced into the chamber 150 through the axle is allowed to escape through the vents 178. the wheel as a whole is caused to rotate. As a final example, the outer wall of the tyre can incorporate passages which will create the desired effect. In the right hand side of Fig. 5 a tyre 180 is mounted on a wheel rim. The tyre 180 has a passage 182 moulded into the outer wall thereof which is in communication with the chamber 150 via a connection in the wheel rim. In the radially outer wall of the tyre 180, ie remote from the wheel rim, vents 184 are arranged which allow compressed air travelling down the passage 182 to escape to atmosphere. The vents 184 are arranged so as to produce a tangential element of flow in order to ensure that the passage of air therethrough creates a rotational movement of the wheel. The passage 182 is kept completely separate from the tyre proper; ie there is a substantial dividing wall between the tyre cavity 186 and the passage 182. The vents 184 can also be protected by means of shields (not shown) to prevent damage thereto on landing. It will be appreciated that all of the arrangements illustrated in Figs. 4 and 5 are automatically balanced provided that the radially-extending passages are equiangularly spaced. It will also be appreciated that none of the embodiments illustrated in Figs. 1 to 5 contain moving parts and therefore the cost of maintaining and repairing such parts is eliminated.

Claims: An aircraft wheel (102) consisting of a hub (104) and a rim (106) including apparatus for causing the aircraft wheel to rotate, comprising at least one nozzle or vent (156, 164, 178, 184) located on the circumference of a circle centered on an axle (110) of the wheel (102) and arranged to expel air at least partially circumferentially with respect to the said circle, and air supply means for providing air to the or each nozzle or vent (156, 164, 178, 184) for expulsion therethrough, the air supply means comprising a compressed air source and an air supply passage connecting the compressed air source to the or each nozzle or vent (156, 164, 178, 184), the or each nozzle or vent (156, 164, 178, 184) being rotatable with the wheel (102) such that expulsion of the air through the or each nozzle or vent (156, 164, 178, 184) causes rotation of the wheel and the air supply passage passing through the axle (110) of the wheel, characterized in that the or each nozzle or vent (156, 164, 178, 184) is located, in use, radially outwardly of the outer radial periphery of the aircraft wheel. An aircraft wheel (102) as claimed in Claim 1, wherein a portion of the air supply passage is formed by a chamber (150) located within a hub of the wheel. An aircraft wheel (102) as claimed in Claim 1 or 2, wherein a portion of the air supply passage is located inside a tyre (108) attached to the rim (106) of the wheel. An aircraft wheel (102) as claimed in Claim 3, wherein the portion of the air supply passage located inside the tyre (108) is formed integrally with the said tyre. An aircraft wheel (102) as claimed in Claim 3 or 4, wherein the at least one nozzle or vent or at least some of the nozzles or vents (156, 164, 178, 184) are located on the tyre (108). An aircraft wheel (102) as claimed in Claims 1 to 5, wherein the at least one nozzle or vent or at least some of the nozzles or vents (156, 164, 178, 184) are located on the wheel (102) or an attachment therefor. An aircraft wheel (102) as claimed in Claims I to 6, wherein a plurality of nozzles or vents (156, 164, 178, 184) are equispaced about the circumference. An aircraft wheel (102) as claimed in any one of Claims 1 to 7, wherein the or each nozzle or vent (156, 164, 178, 184) is arranged to expel air substantially tangentially with respect to the said circle. An aircraft having at least one wheel as claimed in any one of the preceding claims.

Inventors: AL-THANI HAMAD ALI JASSIM, AL-THANI, HAMAD ALI JASSIM
Applicants: AL-THANI HAMAD ALI JASSIM, AL-THANI, HAMAD ALI JASSIM
Application year: 1996
Main classification: B64C25
IPC codes: B64C25