Abstract:
The invention provides a control box for selectively delivering orders to receivers ( 8, 12 ), the control box comprising:
       a shaft ( 14 ) mounted to turn about an axis of rotation (X), while being capable of sliding along said axis (X) between a rest position towards which it is urged by return means ( 24 ), and an active position;   order delivery means ( 16, 11 ) co-operating with the shaft ( 14 ) to deliver orders as a function of the angular position of the shaft ( 14 );   rotary drive means ( 15 ) for causing the shaft to turn; and   safety actuation means ( 23 ) for causing the shaft to slide from the rest position in which anti-rotation means ( 27, 28 ) prevent the shaft from turning to the active position in which the anti-rotation means ( 27, 28 ) leave the shaft free to turn under drive from the rotary drive means ( 15 ).

Description:
This application is a Divisional of U.S. application Ser. No. 13/761,767, filed Feb. 7, 2013, which claims priority to French Application No. 12 51189, filed Feb. 8, 2012, the disclosure of each is incorporated herein by reference. 
     The invention relates to a control box, in particular one that is suitable for use in operating an aircraft landing gear hatch on the ground. 
    
    
     BACKGROUND OF THE INVENTION 
     Most modern aircraft have retractable landing gear, wheel wells for receiving the landing gear while the aircraft is in flight, and hatches for closing the wheel wells. The hatches are opened and closed with the help of hatch operating actuators, e.g. hydraulic actuators. 
     When the hatch reaches the closed position, it is automatically locked in this position by hooking means, e.g. a hooking box having a hook hinged thereto that holds captive a roller fastened to the hatch. The hook is unhooked with the help of an actuator, usually a hydromechanical or an electromechanical actuator. Often the hooking box includes an emergency actuator capable of unlocking the hook in the event of it not being possible to use the main actuator. 
     In flight, the unhooking of the hook and the opening and closing of the hatch are controlled during sequences for extending and retracting the landing gear. It should be observed that the hatches are reclosed and hooked once the landing gear has been deployed. 
     When the aircraft is on the ground, it is necessary to be able to open the hatches, in particular in order to access equipment situated on the top portion of an undercarriage or in the wheel well. For this purpose, most aircraft include mechanical control means that are operable by personnel on the ground and making it possible to deactivate the hooking means in order to release the hatches. 
     These mechanical control means generally include a handle connected to the hooking box by a linkage, together with safety means for ensuring that the handle is not operated in untimely manner. 
     Those mechanical control means are particularly heavy, bulky, and therefore expensive for the aircraft manufacturer. 
     OBJECT OF THE INVENTION 
     An object of the invention is to provide a control box suitable in particular for being used in operating an aircraft landing gear hatch on the ground, which control box is of simplified design. 
     BRIEF SUMMARY OF THE INVENTION 
     In order to achieve this object, the invention provides a control box for selectively delivering orders to receivers, the control box comprising:
         a shaft mounted to turn about an axis of rotation, while being capable of sliding along said axis between a rest position towards which it is urged by return means, and an active position;   order delivery means co-operating with the shaft to deliver orders as a function of the angular position of the shaft;   rotary drive means for causing the shaft to turn; and   safety actuation means for causing the shaft to slide from the rest position in which anti-rotation means prevent the shaft from turning to the active position in which the anti-rotation means leave the shaft free to turn under drive from the rotary drive means.       

     Thus, in order to deliver an order, an operator must act simultaneously on the safety actuation means and on the rotary drive means, thus making it possible to make control safe by avoiding any untimely generation of an order by the shaft accidentally being turned. In this situation, safety consists in preventing any such turning so long as the shaft has not been pushed in, which can thus be implemented in a manner that is particularly simple and light in weight. 
     The invention also provides a device for operating an aircraft landing gear hatch on the ground, the device comprising:
         means for operating the hatch;   hooking means enabling the hatch to be locked when it reaches a closed position, the hooking means including at least one unlocking actuator arranged to act on the hooking means in order to deactivate them; and   a control box as described above, the order delivery means of the control box optionally being connected to the operating means of the hatch and to the unlocking actuator in order to run the following sequences selectively:
           an opening sequence during which the unlocking actuator is actuated to deactivate the hooking means; and   a closing sequence during which the operating means are actuated to reclose the hatch.   
               

     Thus, the hatch cannot be operated inadvertently by the action of an operator on the ground or by any other outside cause. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be better understood in the light of the following description given with reference to the figures of the accompanying drawings, in which: 
         FIG. 1  is a diagrammatic face view of an aircraft wheel well with its hatch and its undercarriage in the deployed position, the aircraft being provided with a control box of the invention for controlling the operation of the hatch on the ground; 
         FIG. 2   a  is a section view of the control box of the invention on an axis of rotation of the handle, the shaft of the control box being in a rest position; 
         FIG. 2   b  is a section view similar to the view of  FIG. 2   a , the shaft of the control box being in an active position; and 
         FIGS. 3 ,  4 , and  5  are diagrams showing portions of the shaft of the control box of the invention in perspective, respectively in a first control state, in a second control state, and in a third control state. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The control box of the invention is described herein in an application to operating aircraft landing gear hatches on the ground, in which application it is particularly useful. Nevertheless, this application is not limiting. 
     The aircraft  1  shown in  FIG. 1  has an undercarriage  2  hinged to its structure to move between a deployed position as shown and a retracted position in which the undercarriage is received in a wheel well  3  that can be closed by a hatch  4 . An actuator  5  coupled to the hatch  4  enables it to be operated. When the hatch  4  reaches a closed position, a hooking box  6  having a hook  7  serves to hook onto a roller  60  that is carried by the hatch  4 . Unhooking of the hook  7  is controlled by an electromechanical actuator  8 . 
     In order to control operation of the hatch  4  while on the ground, and in particular in order to unhook the hook  7 , the aircraft has a control box  9  of the invention that is accessible by opening a door  10 . The control box  9  in this example is electrically connected to an electrical unit  11  that is arranged to control an electrohydraulic solenoid valve  12  connected to the actuator of the hatch  5  and to control the electromechanical actuator  8  of the hooking box  6 . The various functional connections between the above-mentioned pieces of equipment are shown diagrammatically in  FIG. 1  by dashed lines. 
     The control box  9 , shown in detail in  FIGS. 2   a  and  2   b , comprises:
         a body  13  fastened to the aircraft  1 ;   a shaft  14  tunable about an axis X and also axially movable along the same axis X;   a handle  15  for being turned about the axis X by an operator on the ground, and co-operating with the shaft  14  in order to turn it; and   a processor  16  (visible in  FIG. 1 ) enabling the angular position of the shaft  14  to be delivered to the electrical unit  11  in order to control an operation of the hatch  4  as a function of the angular position of the shaft  14 .       

     The handle  15  has a grip portion  17  for being gripped by the operator that projects from a hollow hub  18  extending around the shaft  14 . The hub  18  is engaged in a cavity  19  of the body  13  in order to guide it in turning about the axis X, and it is held in place by a stop washer  20 . The hub  18  and the shaft  14  have complementary fluting  21 ,  22  enabling the shaft  14  to be turned by the handle  15  while also allowing the shaft  14  to move axially. 
     The shaft  14  is generally oblong in shape, and has an end  23  that extends to the center of the hub  18  of the handle  15  that is accessible to the operator, such that the end  23  forms an actuator member on which the operator can press in order to cause the shaft  14  to slide axially between a rest position shown in  FIG. 2   a  and an active position shown in  FIG. 2   b . A spring  24  extends between a step  25  in the body and a collar  26  on the shaft  14  in order to urge the shaft  14  towards the rest position. 
     Grooves  27  in the shaft  14  co-operate with a finger  28  secured to the body  13  in such a manner that:
         in the rest position, the finger  28  is engaged in one of the grooves  27  so as to prevent the shaft  14  from turning; and   in the active position, the finger  28  is disengaged from the grooves  27  so that the shaft  14  is free to turn under the effect of drive applied to the handle  15  by the operator.       

     The shaft  14  also has an annular portion  30  serving to transform the angular position of the shaft  14 , as controlled by the handle  15 , into orders for the electrical unit  11  for controlling the solenoid valve  12  and the electromagnetic actuator  8 . As can be seen in  FIG. 3 , this angular position  30  defines a cam  31  having two projections  32  adapted to interact with three contactors  33  situated in the body of the control box and including fingers  34  that extend into the cavity  19  in order to be pushed back if a projection  32  of the cam  31  comes into register with the associated contactor  33 . Each of the different angular positions of the shaft (visible in  FIGS. 3 ,  4 , and  5 , and referred to herein as “OPEN”, “FLIGHT”, and “CLOSE”) thus corresponds to a respective particular combination of the states of the contactors, thereby enabling each angular position to be recognized. The contactors  33  are connected to the processor  16  so that it can act, as a function of the indications from the contactors, to determine the angular position of the shaft  14  and send said position to the electrical unit  11 . 
     Thus, in order to operate the hatch  4 , it is necessary for an operator to perform two actions simultaneously, consisting in pressing on the end  23  of the shaft  14  and in turning the handle  15 , thus making it possible to avoid any unintended control. Finally, the shaft  14  has a partially recessed portion  35  comprising a recess  36  and a solid portion  37  that are adapted to interact with a fourth contactor  38  having its finger  39  pushed back when the solid portion  37  comes into register with the contactor  38 . The contactor  38  thus detects whether the shaft  14  is in the active position or the rest position. The contactor  38  is connected to the processor  16  of the control box  9 . When the contactor  38  detects an active position of the shaft  14  that causes the processor  16  to be powered together with the electrical unit  11 , with its electricity consumption thus remaining zero so long as the hatch  4  is not being operated. 
     Depending on the angular position of the handle  15 , the electrical unit  11  runs:
         an opening sequence (handle in the “OPEN” position) during which the electromechanical actuator  8  is activated in order or release the roller  10  of the hatch  4 , the solenoid valve  12  is then activated so that both chambers of the hatch actuator  5  are connected, with the resulting force opening the hatch  4  after it has been released;   a closing sequence (handle  15  in the “CLOSED” position) during which the solenoid valve  12  is actuated so that the hatch actuator  5  recloses the hatch  4 , with the hatch  4  then being hooked automatically when it reaches the closed position; and   an isolating sequence (handle in the “FLIGHT” position) that serves to ensure electrical isolation between the control box  9  and the remainder of the electricity circuit of the aircraft, thus making it possible to guarantee that no operation of the hatch  4  will be triggered in untimely manner.       

     In order to allow an operator on the ground to run a sequence, it is necessary for certain predetermined conditions to be satisfied, including:
         in order to run a closing sequence when the hatch  4  is open, it is necessary for both electrical and hydraulic energy to be available;   in order to run an opening sequence, it is necessary for electrical power to be available; and   it is not permitted to run an isolating sequence while the hatch  4  is open.       

     The body  13  of the control box  9  has two linear electrical solenoid actuators  40  interacting with the grooves  27  of the shaft  14 . The movable portion of each actuator  40  is a rod  41  that slides in a radial direction relative to the shaft  14 . These actuators  40  are controlled by the processor  16  of the control box  9 . 
     When the predetermined conditions are not satisfied, the rod  41  of the actuators  40  are engaged in the grooves  27  of the shaft  14  in the manners shown in  FIGS. 3 ,  4 , and  5  corresponding respectively to the “OPEN”, “CLOSE”, and “FLIGHT” positions. Thus, for each of the “OPEN”, “CLOSE”, and “FLIGHT” positions of the handle, the shaft presents at least one groove  27  in register with at least one actuator  40  in order to prevent the handle  15  from turning. 
     Unlike the position of the stationary finger  28 , the positions of the rods  41  of the actuators  40  are such that they can be engaged in the grooves  27  regardless of the longitudinal position of the shaft  14 : if the predetermined conditions are not satisfied, then the handle  15  is blocked even if the operator presses on the end  23  of the shaft  14 . 
     An indexing ball  42  (visible in  FIGS. 3 ,  4 , and  5 ) is mounted to slide in a housing  43  provided in the body of the control box, in such a manner that the ball  42  is flush with the surface of the cavity  19  in order to co-operate with the shaft  14  via the grooves  27 . The ball  42  is urged resiliently by a spring  44  to index turning of the shaft  14  for the purpose of aligning the grooves  27  in register with the rods  41  of the actuators  40  and for the purpose of providing the operator with physical feedback informing the operator whether the shaft is in a predefined OPEN, FLIGHT, or CLOSE position, or else is in an intermediate position. 
     The invention is not limited to the particular embodiment described above, but on the contrary covers any variant coming within the ambit of the invention as defined by the claims. 
     Although a particular number of angular position detectors are detected above and although these detectors are selected to be made using a particular technology based on contactors, and although a particular technology has been selected for the actuators, it is possible to provide for some other number and to use other technologies. For example, it is possible to use a Hall effect angular position sensor, with the magnet of the sensor occupying the shaft in such a manner as to interact electromagnetically with the detector regardless of the axial position of the shaft  14 . Similarly, the general shape of the shaft and the relative positions of the elements in the cavity may be different, providing a portion of the shaft is suitable for co-operating with the angular position detector. 
     Although in this example the control box incorporates a processor for communicating with an external electrical unit, it is possible to provide for the processor and the external electrical unit to be incorporated in the control box or else in external equipment. It is also possible for the position of the shaft to be acquired and/or for orders to be transmitted in some other way, e.g. mechanically. 
     Although the control box described is for operating a landing gear hatch from the ground, it is possible to use the control box in any other application. 
     Finally, although the safety actuation means as described herein are constituted directly by the end of the shaft on which the operator presses, the safety actuation means could comprise a mechanical, electromechanical, or hydraulic actuator arranged to move the shaft axially under the control of the operator.