Patent Abstract:
The invention relates to axle end equipment for a vehicle, in particular an aircraft, the equipment comprising a stationary portion for securing to the axle and a rotary portion for securing to the wheel carried by the axle. According to the invention, the rotary portion comprises first remote connection means in communication with a sensor mounted on the wheel so as to put the sensor and the rotary portion of the equipment into contactless electromagnetic relationship.

Full Description:
The invention relates to axle end equipment for a vehicle, in particular an aircraft. 
   BACKGROUND OF THE INVENTION 
   Axle end equipments for vehicles, in particular aircraft, are known that comprise a stationary portion for being placed in the axle and a rotary portion for being secured to a wheel carried by the axle. 
   For example, such equipment may include a tachometer for measuring the speed of rotation of the wheel, and a pressure sensor for measuring the pressure that exists in a tire fitted to the wheel. 
   The pressure sensor is connected by a cable to the rotary portion. When the wheel is removed, the operator must disassemble the rotary portion and the pressure sensor, and as a result the pressure sensor and the connection between the rotary portion and the pressure sensor run the risk of being damaged. 
   OBJECT OF THE INVENTION 
   An object of the invention is to provide equipment that does not present the above-specified drawback. 
   BRIEF DESCRIPTION OF THE INVENTION 
   In order to achieve this object, the invention provides axle end equipment for a vehicle, in particular an aircraft, the equipment comprising a stationary portion for securing to the axle and a rotary portion for securing to the wheel carried by the axle, the equipment including first remote connection means for putting a sensor mounted on the wheel into contactless electro-magnetic relationship with the rotary portion of the equipment. 
   It is thus possible to remove the rotary portion without worrying about the sensor, which, since it has no mechanical or electrical connection with the rotary portion, can be left on the wheel without any risk of damage. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention can be better understood in the light of the following description given with reference to the accompanying drawings, in which: 
       FIG. 1  is a section view of the end of an aircraft axle fitted with equipment constituting a first embodiment of the invention; 
       FIG. 2  is a perspective view of a portion of the equipment shown in  FIG. 1 , the sleeve and the tachometer being removed; 
       FIG. 3  is a section view of the end of an aircraft axle fitted with equipment constituting a second embodiment of the invention, integrating a fan for cooling the brake with which the wheel is fitted; 
       FIG. 4  is a section view of the end of an aircraft axle fitted with equipment constituting a third embodiment of the invention; 
       FIG. 5  is a perspective view of the equipment shown in  FIG. 4 ; 
       FIG. 6  is a section view analogous to that of  FIG. 1  showing a variant of the first embodiment; 
       FIG. 7  is a section view of the end of an axle fitted with equipment constituting a fourth embodiment of the invention; and 
       FIG. 8  is a fragmentary perspective view of the  FIG. 7  wheel showing the pressure sensor. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   In a first embodiment shown in  FIGS. 1 and 2 , the equipment of the invention is associated with an axle end  1  carrying a wheel  2  of which one half-rim  3  can be seen (the other half-rim being silhouetted as a dashed line). 
   The equipment shown serves to measure continuously the speed of rotation of the wheel  2  and also the pressure that exists in the tire mounted on the wheel  2  (shown in dashed-line outline). 
   For this purpose, the equipment comprises a stationary portion  100  comprising a sleeve  101  inserted in the axle  1  and carrying a tachometer  102  having a shaft  103  that extends along the axis of rotation X of the wheel  2 . 
   The equipment also comprises a rotary portion  200  comprising a cap  201  secured to the half-rim  3  by a clamping collar  202 . The cap  201  carries internally a driver  203  adapted to co-operate with the shaft  103  of the tachometer  102  in order to drive said shaft in rotation when the wheel  2  is rotating. The tachometer  102  includes a first connector  104  having a first cable (not shown) connected thereto and passing along the inside of the axle. 
   According to the invention, the stationary portion  100  includes a cylindrical portion  105  that extends concentrically about the axis of rotation X of the wheel  2  and that carries a first antenna  106 , in this case a winding of an electrical conductor. The first antenna  106  is connected to a second connector  107  carried by an extension of the sleeve  101  to which a second cable (not shown) is connected that passes along the inside of the cable. 
   The rotary portion has a cylindrical portion  205  that extends concentrically about the axis of rotation X of the wheel  2  and that carries a second antenna  207  also constituted by a winding of electrical conductor. This antenna extends facing the first antenna  106  of the stationary portion  100 , such that the two antennas interact electromagnetically. 
   The second antenna  207  is connected by a cable  208  to a third antenna  109  carried by a projection  210  of the cap  201  and constituted by a winding of an electrical conductor. 
   Facing the third antenna  209  there extends a pressure sensor  211 , which in this example is screwed on a self-closing valve  212 , itself screwed to the half-rim  3  and enabling the pressure sensor  211  to be removed without deflating the tire. The valve  212  is placed at the end of an orifice that communicates with the inside of the tire through the half-rim  3 . 
   The pressure sensor  211  has a fourth antenna  214  constituted by a winding of an electrical conductor that extends facing the third antenna  209  such that these two antennas interact electromagnetically. The pressure sensor  211  comprises a pressure-sensitive member associated with the fourth antenna  214  so as to cause at least one electromagnetic characteristic of the fourth antenna  214  to vary in response to a pressure level inside the tire. 
   The device of the invention operates as follows. When the wheel  2  is rotating, the driver  203  that rotates with the wheel  2  drives the shaft  103  of the tachometer so that it rotates, and thus causes a signal to be produced in response that is representative of the speed of rotation of the wheel  2 . 
   In addition, regardless of whether the wheel  2  is rotating or stationary, the first and second antennas and also the third and fourth antennas continue to remain in electromagnetic interaction, while the second and third antennas are interconnected electrically. As a result, the electromagnetic characteristics of the first antenna  106 , i.e. the antenna that is connected directly to the connector  107 , are influenced by means of the pressure sensor via the electromagnetic connection thus established. It then suffices to apply a current to the first antenna  106  and to read the voltage that appears across the terminals of said antenna in order to obtain a signal that is representative of the pressure that exists inside the tire. 
   The device of the invention presents several advantages:
         it is very easy to remove the wheel  2 . It suffices to remove the clamping collar  202  so as to be able to remove the cap  201 . Since the cap is not connected by any electrical wiring, whether to the connectors  104 ,  107  or to the pressure sensor  211 , it is removed very easily without any risk of damaging a connection. In addition, the only mechanical connection between the stationary portion  100  and the rotary portion  200  is constituted by co-operation between the driver  203  and the shaft  103  of the tachometer  102 . Removing the cap  201  disconnects the driver  203  from the shaft  103  and gives access to the nut that holds on the wheel  2 . To put the cap  201  back into place, it suffices to ensure that the driver  203  co-operates properly with the shaft  103  of the tachometer  102 , and that the third antenna  209  is generally in register with the pressure sensor  211 ;   the pressure sensor  211  can be changed independently of the remainder of the device of the invention. In addition, making use of a self-closing valve makes such a changeover much easier;   it is possible without any disassembly to test the pressure sensor  211  by means of an external unit  300  provided with an antenna  301  that is moved up to the antenna  214  of the pressure sensor  211 , such that these two antennas interact electromagnetically. The external unit should include its own electrical power supply adapted to cause a current to flow in the antenna  301 . The voltage across the terminals of said antenna depends on the pressure that exists inside the tire, thus enabling the operator to measure the pressure inside the tire and possibly decide on taking maintenance action (re-inflation, changing the wheel, or changing the sensor if the sensor is found to be faulty); and   the electrical and mechanical systems of the tachometer and of the pressure sensor are completely segregated, such that the failure of one does not lead to the failure of the other.       

   In a second embodiment of the invention, as shown in  FIG. 3 , the equipment of the invention may also incorporate a fan for cooling a brake with which the wheel  2  is fitted. References for elements that are common with the first embodiment have the same numbers as in  FIGS. 1 and 2 , together with prime symbols. 
   In the same manner as before, the sleeve  101 ′ carries a first antenna  106 ′. The cap  102 ′ carries a second antenna  207 ′ facing the first antenna  106 ′ so that the first and second antennas interact electro-magnetically. The cap  201 ′ carries a third antenna  209 ′ electrically connected to the second antenna  207 ′. A pressure sensor  211 ′ is implanted on the half-rim  3  and includes a fourth antenna  214 ′ that faces the third antenna  209 ′ so that the third and fourth antennas interact electromagnetically. 
   This equipment differs from the above equipment by the tachometer  102  being replaced by a combined motor and tachometer unit  112 ′. The combined unit  112 ′ comprises a motor  113 ′ that is secured to the sleeve  101 ′ and that has a hollow shaft  114  that can be seen projecting towards the end of the axle  1 , and that receives at its end the impeller  115 ′ of a cooling fan. The combined unit  112 ′ also includes a tachometer  116 ′ placed behind the motor  113 ′ and having its shaft  117 ′ extending inside the hollow shaft  114 ′ of the motor  113 ′ so as to project beyond the end thereof. 
   The rotary portion  200 ′ of the equipment includes a cap  201 ′ that receives a casing  220 ′ for protecting the impeller  115 ′, and also a mask  221 ′ that covers the entire hollow portion of the half-rim  3 . 
   In order to remove the wheel  2 , the casing  220 ′ and the mask  221 ′ are removed initially so as to gain access to the impeller  115 ′. The nut that secures the impeller  115 ′ to the hollow shaft  114 ′ of the motor  113  is removed in order to enable the impeller  115 ′ to be removed, and then the cap  201 ′ is removed so as to give access to the nut that holds on the wheel  2 . 
   In the same manner as before, none of the elements constituting the equipment of the invention that are disassembled in order to gain access to the wheel has any electrical connection with the pressure sensor or any other element, such that disassembling these elements leads to no risk of damaging a connection. In addition, the only mechanical connection between the stationary portion  100 ′ and the rotary portion  200 ′ is constituted by the co-operation between the driver  203 ′ (in this case secured to the casing  220 ′) and the shaft  117 ′ of the tachometer  116 ′. This connection is easily disconnected merely by removing the casing  220 ′. 
   In a third embodiment shown in  FIGS. 4 and 5 , use continues to be made of a combined motor and tachometer unit. Nevertheless, the tachometer is no longer placed behind the motor, but instead it is placed around it. In these figures, the references for elements that are common with similar elements in the second embodiment are given the same numbers as in  FIG. 3 , associated with double primes. 
   As can be seen in  FIG. 4 , the sleeve  101 ″ has a rear face that carries the motor  113 ″ of the combined unit  112 ″. The motor has a shaft  114 ″ that extends to receive an impeller  115 ″ of the fan. 
   The sleeve  101 ″ receives the tachometer directly, and for this purpose it includes bearings  120 ″ that guide a pushing  121 ″ in rotation. Between the sleeve  101 ″ and the bushing  121 ″ there extend means  122 ″ for measuring speed of rotation (represented by a cross in the drawings), e.g. variable reluctance means. The bushing  121 ″ extends around the end of the motor  113 ″, and is free to rotate relative thereto. 
   The bushing  121 ″ is constrained to rotate with the cap  201 ″ of the rotary portion  200 ″ by means of screws  123 ″ (only one screw is visible in  FIG. 4 ). Thus, the rotation of the wheel  2  is transmitted to the bushing  121 ″ so that the measurement means  122 ″ generate an electrical signal in response to rotation of the bushing  121 ″. 
   In the same manner as above, the sleeve  101 ″ carries a first antenna  106 ″. The cap  201 ″ carries a second antenna  207 ″ in register with the first antenna  106 ″ so that the first and second antennas interact electro-magnetically. The cap  201 ″ carries a third antenna  209 ″ electrically connected to the second antenna  207 ″. A pressure sensor  211 ″ is implanted in the half-rim  3  and includes a fourth antenna  214 ″ that extends in register with the third antenna  209 ″ so that the third and fourth antennas interact electromagnetically. 
   As above, none of the elements of the equipment of the invention that are disassembled in order to gain access to the wheel has any electrical connection with the pressure sensor or any other element, such that disassembling these elements does not lead to any risk of damaging a connection. In addition, the only mechanical connection between the stationary portion  100 ″ and the rotary portion  200 ″ is constituted by screws  123 ″ between the bushing  121 ″ and the cap  201 ″. This drive is easily disassembled merely by unscrewing the screws  123 ″ that become accessible once the impeller  115 ″ has been removed. 
   Preferably, between the second and third antennas ( 207 / 209 ,  207 ′/ 209 ′,  207 ″/ 209 ″), i.e. between the antennas that are secured to the rotary portion, electro-magnetic tuning is provided, e.g. by means of capacitors, so that the circuit comprising the second antenna and the third antenna is resonant at the frequency of the power supply current fed to the first antenna ( 106 ,  106 ′,  106 ″). This increases the transmission quality of the pressure acquisition connection, thus making it possible to have a greater distance between the third antenna and the fourth antenna (the antenna secured to the pressure sensor), thus making it possible to reduce the risk of collision between the pressure sensor and the cap when the cap is being removed from the wheel. 
     FIG. 6  shows a variant of the first embodiment in which the first antenna  106  is carried at the end of the sleeve  101  which extends outwards from the axle  1 . Thus, the stationary portion of the equipment need not be contained completely within the axle, but may project therefrom, at least in part. 
   The second antenna  207  is still carried by the cylindrical portion  205  secured to the cap  201 , but in this variant the cylindrical portion  205  extends inside the sleeve  101 , such that the second antenna  207  extends inside the first antenna  106 . It should be observed that the second antenna does not penetrate into the axle  101 . 
   In a fourth embodiment shown in  FIGS. 7 and 8  and that does not include a tachometer, the fourth antenna  214  is no longer secured directly to the pressure sensor  211  but is offset so as to be closer to the cap  201  of the rotary portion  200 . 
   For this purpose, the pressure sensor  211  is associated with a carrier member  220  having two branches that extend against the flanks of spokes of the half-rim  3  of the wheel  2 , matching the shape of the gaps between the spokes. The ends of the branches meet in order to receive the fourth antenna  214  which is thus located close to the cap  201  of the rotary portion  200 . The carrier member  220  is designed to be lightly forced between the spokes of the half-rim  3 , so as to avoid any vibration of the fourth antenna  214 . 
   The carrier member  220  houses connection wires between the pressure sensor  211  and the fourth antenna  214 , so as to ensure that the wires are protected from impacts. 
   The third antenna  209  is carried by a projection  221  that extends from the cap  201  but that is much shorter than the projection  210  of the first embodiment shown in  FIG. 1 , such that the cap  210  is generally more compact and easier to handle. 
   The connection wires  208  connecting the third antenna  209  to the second antenna  207  is completely sheltered by the cap and by the projection  221 . 
   It should be observed that the third antenna  209  is designed to overlap the fourth antenna  214 , thus informing the person carrying out assembly about the angular position of the cap  201  relative to the pressure sensor  211 . The third antenna  209  and the fourth antenna are thus much closer together, thereby improving the efficiency of transmission. 
   The invention is not limited to the description above, but on the contrary covers any variant coming within the ambit defined by the claims. 
   In particular, although the sensor implanted on the rim is described as being a pressure sensor, the invention naturally covers the use of other sensors, e.g. a temperature sensor. 
   Although the equipment shown herein has remote connection means each comprising a pair of antennas in electromagnetic interaction, it is possible to use any other remote connection means, for example infrared means. 
   Although it is stated that two remote connection means are used, such that the rotary portion has no physical electrical connection either with the sensor or with the rotary portion, the invention also covers equipment in which the only remote connection extends between the rotary portion and the sensor. Under such circumstances, it is necessary to provide an electrical connection of some other type between the rotary portion and the stationary portion, for example a connection by means of brushes.

Technology Classification (CPC): 1