Abstract:
An airplane high lift surface drive system having a first actuator connected to a first high lift surface and a second actuator connected to a second high lift surface, wherein the first actuator is electrically connected to the second actuator in series.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to an apparatus for controlling airplane high lift surfaces, and more specifically, airplane leading edge flaps, or slats, or trailing edge flaps. 
     One type of prior art airplane flap drive system uses a centrally located power drive unit with mechanical transmission to the flap locations. The power drive unit includes either an electrical motor, a hydraulic motor or both types of motor. Because the power drive unit is not located at the flap locations, additional transmission components are required to connect the power drive unit to the flaps. 
     Another type of prior art airplane flap drive system uses separate power drive units positioned at each flap location. Each power drive unit includes an electric motor having its own controller. During repositioning of the flaps, both flaps require approximately the same torque output (within a given tolerance) from their respective drive motors. A separate controller is used to drive each motor such that both flaps move in a similar manner. Any position difference between the left and right flaps is eliminated through use of a synchronizer mechanism such as a torque bar. 
     In view of the foregoing, it is an object of this invention to provide a simplified airplane high lift surface drive system apparatus. 
     It is also an object of this invention to provide an airplane high lift surface drive system apparatus that eliminates the need for multiple controllers and that drives airplane flaps. 
     It is another object of this invention to provide an airplane high lift surface drive system apparatus that eliminates the need for multiple controllers and includes power drive units or actuators positioned near the flap locations. 
     SUMMARY OF THE INVENTION 
     These and other objects of the invention are accomplished in accordance with the principles of the invention by using multiple drive motors that are electrically connected to each other in series and are governed by a single controller. 
     Further features of the invention, its nature and various advantages will be more apparent from the accompanying drawings and the following detailed description of the preferred embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram of one embodiment of the circuitry of the invention. 
     FIG. 2 is a perspective view of one embodiment of the invention. 
     FIG. 3 is a schematic diagram of a portion of another embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a schematic diagram of a preferred embodiment of the invention. FIG. 2 is a perspective view of a preferred embodiment of the invention. Referring to FIGS. 1 and 2, motor  1  and motor  2  are similar, preferably direct current, motors included in actuator  30  and actuator  40  (shown in FIG.  2 ), respectively. Actuators  30  and  40  drive high lift surfaces  10  and  20  (shown in FIG.  2 ), respectively. High lift surfaces  10  and  20  may be left and right trailing edge flaps or left and right leading edge flaps (slats). Positioning actuators  30  and  40  at the high lift surface locations eliminate the need for extended transmission components that would be necessary if the high lift surfaces were driven from a centrally located power drive unit. 
     Referring to FIG. 1, motors  1  and  2  are electrically connected in series to each other and therefore share the same current. Because torque and current are related monotonically in direct current motors and motors  1  and  2  share the same current, motors  1  and  2  produce approximately the same torque (within a given tolerance). A single controller  11  regulates the current provided to motors  1  and  2  that drives the motors in a similar manner. Separate controllers for motors  1  and  2  are not needed to drive the motors and move their loads in a similar manner. 
     Motors  1  and  2  are connected to power bridge  5 . Power bridge  5  produces the output of controller  11  and is wired in series with motors  1  and  2 . Position detector  3  and position detector  4  are potentiometers or resolvers that provide signals indicative of the position of high lift surfaces  10  and  20  driven by actuator  30  and actuator  40 , respectively. Position detectors  3  and  4  are connected to position comparator  8  which produces a position feedback signal corresponding to the average of the positions of high lift surfaces  10  and  20 . Position comparator  8  also produces a signal indicative of asymmetry between position detectors  3  and  4 . The position feedback signal is summed with a position command signal in operational amplifier  7  to generate an error signal. The position command signal is a steady electrical potential corresponding to a desired high lift surface position selected by the system operator. Monitoring block  9  receives the error signal and enables or disables pulse width modulation controller  6  according to several control factors, including the level of asymmetry between position detectors  3  and  4 . If enabled by monitoring block  9 , pulse width modulation controller  6  drives power bridge  5  to run motors  1  and  2  in the proper direction to cancel the error signal. Monitoring block  9  disables pulse width modulation controller  6  when the error signal falls below a certain value. 
     During normal operation, the high lift surface drive system moves the left and right high lift surfaces such that they synchronously extend and retract. Motors  1  and  2  both generate torque corresponding to the current provided by power bridge  5 . Because motors  1  and  2  may experience different loads causing the resulting position of high lift surfaces  10  and  20  to differ, a torque transfer mechanism between motors  1  and  2  must be used to assure synchronous movement of the high lift surfaces and the same resultant position. Referring to FIG. 2, one embodiment of the invention includes a torque tube  50  for transferring torque between motors  1  and  2  as necessary to assure synchronous movement of high lift surfaces  10  and  20 . Torque tube  50  is connected between high lift surfaces  10  and  20  through attachment to high lift surface hanger arms  60  and  70 , respectively. In order to assure synchronization, the torque transfer mechanism may be attached between the high lift surfaces either directly, or indirectly through other components, including attachment to outputs of the electric motors. 
     FIG. 3 is a schematic diagram showing an alternate means for transferring torque between motors to assure synchronous movement of high lift surfaces  10  and  20 . Shaft  90  is a relatively low-weight synchronizing shaft that is mechanically connected to the outputs of motors  1  and  2  through step up gearboxes  70  and  80 . 
     One skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which are presented here for purposes of illustration and not of limitation, and the present invention is limited only by the claims that follow.