Abstract:
A helicopter rotor blade having a blade body that defines a confined space and a control flap that is secured to the blade body that moves through a range of motion. An electric machine is secured inside of the rotor blade body that rotates a motor shaft. A transmission device is secured to the motor shaft and the control flap that transfers rotary motion of the motor shaft to the control flap to generate movement of the control flap through its range of motion. The transmission device remains substantially within the confined space throughout the range of motion.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present disclosure relates to helicopter rotor blades. More specifically, the present disclosure relates to an on-blade actuator for helicopter rotor blade control flaps. 
         [0003]    2. Description of Related Art 
         [0004]    The operation and performance of helicopter rotor blades is significant to the overall performance of a helicopter. The vertical lift and the forward and lateral movement of the helicopter are all made possible by the operation of the rotor blades. A swashplate located around the rotating shaft of a helicopter is conventionally used to mechanically control the movement of individual blades by producing their pitch for rotor thrust control (tilt of thrust and thrust magnitude). The traditional method for producing the pitch motion is by directly driving at the blade root via the swashplate. But, the swashplate is an extremely complex, very heavy and maintenance intensive mechanical system. The elimination of the swashplate can result in many benefits such as reduced empty weight and drag, and increased maintainability. 
         [0005]    Recently, on-blade control flaps have been used on the main rotor blades of helicopters to reduce the required power of actuation by controlling the pitch motion and higher harmonics of the blades during flight. Instead of the swashplate, the control flaps are driven by an on-blade actuator that produces the pitch motion of the blades by directly driving at the flap. The control flaps deflect to induce a hinge moment on the blade via the aerodynamics of the air stream acting on the flap. This moment then generates the required pitch motion of the blade about the blade pitch axis with an order of magnitude that is less power than direct driving of the blade. The control flaps can be used for both primary flight control (PFC), as well as vibration reduction and acoustic noise reduction known as high harmonic control (HHC). The control flaps eliminate the need for a swashplate, swashplate linkages, main rotor servo flaps, pitch links, main rotor bifilar, and the associated hydraulic system. Unfortunately, prior art on-blade actuators have not proven effective at reducing power consumption to desired levels. Additionally, prior art on-blade actuators have proven to be very maintenance intensive. 
         [0006]    Accordingly, there is need for on-blade actuation mechanisms that overcome, mitigate and/or alleviate one or more of the aforementioned and other deleterious effects of the prior art. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    The present disclosure provides a helicopter rotor blade having a blade body that defines a confined space and a control flap that is secured to the blade body that moves through a range of motion. An electric machine is secured inside of the rotor blade body that rotates a motor shaft. A transmission device is secured to the motor shaft and the control flap that transfers rotary motion of the motor shaft to the control flap to generate movement of the control flap through its range of motion. The transmission device remains substantially within the confined space throughout the range of motion. 
         [0008]    The above-described and other features and advantages of the present disclosure will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0009]      FIG. 1  illustrates a perspective view of a helicopter having rotor blades with control flaps that include an exemplary embodiment of an on-blade actuator according to the present disclosure; 
           [0010]      FIG. 2  is a sectional view of a rotor blade taken along lines  2 - 2  of  FIG. 1  illustrating a first exemplary embodiment of the on-blade actuator; 
           [0011]      FIG. 3  is a sectional view of the first exemplary embodiment of the on-blade actuator taken along lines  3 - 3  of  FIG. 2 ; 
           [0012]      FIG. 4  is a sectional view of a rotor blade illustrating a second exemplary embodiment of the on-blade actuator; 
           [0013]      FIG. 5  is a sectional view of the second exemplary embodiment of the on-blade actuator taken along lines  5 - 5  of  FIG. 4 ; 
           [0014]      FIG. 6  is a sectional view of a rotor blade illustrating a third exemplary embodiment of an on-blade actuator according to the present disclosure; 
           [0015]      FIG. 7  is a sectional view of a rotor blade illustrating a fourth exemplary embodiment of an on-blade actuator according to the present disclosure; and 
           [0016]      FIG. 8  is a sectional view of a rotor blade illustrating a fifth exemplary embodiment of an on-blade actuator according to the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    Referring now to the drawings and in particular  FIG. 1 , a helicopter generally referred to by reference number  10  is shown. Helicopter  10  includes one or more rotor blades  12  configured for rotation in a rotor direction  14 . Each rotor blade  12  has a blade body  40  and one or more control flaps (three shown)  16  disposed thereon. 
         [0018]    In the illustrated embodiment, control flaps  16  are disposed on a trailing edge  18  of rotor blade  12 . As used herein, the trailing edge  18  is defined as the edge of rotor blade  12  that follows or trails the movement of the rotor blade as the blade is rotated in the rotor direction  14 . Of course, it is contemplated by the present disclosure for control flaps  16  to be disposed on a leading edge  20  of the rotor blade  12 . Additionally, it is contemplated by the present disclosure for control flaps  16  to be disposed on any combination of the trailing and leading edges  18 ,  20 , respectively. 
         [0019]    In accordance with the principles of the present disclosure, the pitch of each control flap  16  is controlled by an actuator  22  on board each rotor blade  12 , namely within body  40  of the rotor blade. In this manner and when used on the trailing edge  18 , control flaps  16  can be used to replace the swashplate of the prior art. Further, when used on the leading edge  20 , control flaps  16  can be used to impart enhanced performance by delaying retreating blade stall. 
         [0020]    Advantageously, actuator  22  is configured to rotate control flaps  16 , but is sufficiently compact to fit into a confined space  48  defined by the exterior shape of rotor blade  12 . In this manner, actuator  22  minimizes and/or eliminates any portion of the actuator from protruding from confined space  48  during use so that the actuator does not effect the aerodynamics of rotor blade  12 , which enhances the effect of control flaps  16  on the airstream. 
         [0021]    Referring now to  FIG. 2 , an exemplary embodiment of actuator  22  according to the present disclosure is shown. Actuator  22  includes an electric machine  24  and a transmission device  28  that couples the motion and torque generated by electric machine  24  and transmits it to control flap  16 . Transmission device  28  is connected to control flap  16  via a rigid connector  42 . In a preferred embodiment, electric machine  24  is a direct current brushless motor and transmission device  28  is a three-stage gear train  26  with a swing arm  46  that converts forward and backward rotary motion from gear train  26  into forward and backward movement of control flap  16  about an axis  64 . Gear train  26  is housed in a gear case  44 . 
         [0022]    Actuator  22  is mounted within rotor blade body  40  so that the mass or weight of the actuator is centered proximate to the leading edge  20  of rotor blade  12 . 
         [0023]    Referring now to  FIG. 3 , a sectional view of actuator  22  according to the present disclosure is shown, taken along lines  3 - 3  of  FIG. 2 . Actuator  22  has a motor shaft  50  that is rotated by electric machine  24  along an axis of rotation  52 . Transmission device  28  transmits the rotary motion from shaft  50  to control flap  16 . 
         [0024]    In the illustrated embodiment, transmission device  28  includes a first stage  54 , a first transmission shaft  56 , a second stage  58 , a second transmission shaft  60 , a third stage  62 , and a swing arm,  46 . Motor shaft  50  rotates first stage  54  of transmission device  28 . Transmission shaft  56  converts motion from first stage  54  of transmission device  28  to second stage  58  of the transmission device. Second transmission shaft  60  converts motion from second stage  58  of transmission device  28  to the third stage  62  of the transmission device. Swing arm  46  transfers the motion from third stage  62  of transmission device  28  to control flap  16 , so that the control flap rotates about an axis of rotation  64  of control flap  16 . Swing arm  46  is connected to control flap  16  via rigid connector  42 . 
         [0025]    In the illustrated embodiment, the axis of rotation  52  of motor shaft  50  is parallel to the axis of rotation  64  of control flap  16 . Of course, it is contemplated by the present disclosure for transmission device  28  to be configured so that axes of rotation  52 ,  64  are angled (i.e., not parallel) to one another. 
         [0026]    Accordingly, actuator  22  maintains electric machine  24  and transmission device  28  substantially within confined space  48  and, preferably, entirely within the confined space, during the complete range of motion of control flap  16 . 
         [0027]    Referring now to  FIG. 4 , a second exemplary embodiment of actuator  122  according to the present disclosure is shown in which component parts performing similar or analogous functions are labeled in multiples of one hundred. In a preferred embodiment of actuator  122 , transmission device  128  is a three-stage gear train  126  with a sector gear  146  that converts forward and backward rotary motion from gear train  126  into forward and backward movement of control flap  116  about an axis  164 . 
         [0028]    Advantageously, actuator  122  is configured to rotate control flaps  116 , but is sufficiently compact to fit into a confined space  148  defined by the exterior shape of rotor blade  112 . In this manner, actuator  122  minimizes and/or eliminates any portion of the actuator from protruding from confined space  148  during use so that the actuator does not effect the aerodynamics of rotor blade  112 , which enhances the effect of control flaps  116  on the airstream. 
         [0029]    Referring now to  FIG. 5 , a sectional view of actuator  122  taken along lines  5 - 5  of  FIG. 4  is shown. Actuator  122  has a motor shaft  150  that transmits a rotational motion generated from electric machine  124  along an axis of rotation  152  to a first stage  154  of transmission device  128 . A transmission shaft  156  converts motion from first stage  154  of transmission device  128  to a second stage  158  of transmission device  128 . A second transmission shaft  160  converts motion from second stage  158  of transmission device  128  to a third stage  162  of transmission device  128 . Sector gear  146  transfers the motion from the third stage  162  of transmission device  128  to control flap  116  so that the control flap rotates about an axis of rotation  164 . Sector gear  146  is connected to control flap  116  via a rigid connector  142 . The axis of rotation  152  of motor shaft  150  is parallel to the axis of rotation of  164  of control flap  116 . 
         [0030]    Referring now to  FIG. 6 , a third exemplary embodiment of actuator  222  according to the present disclosure is shown in which component parts performing similar or analogous functions are labeled in multiples of two hundred. In a preferred embodiment, electric machine  224  is a direct current brushless motor and transmission device  228  includes a first lever  230  and a second lever  232 . First lever  230  is secured to the shaft (not shown) of electric machine  224  so that the electric machine can rotate the first lever. First and second levers  230 ,  232  are coupled to one another by a sliding pin-slot mechanism  234 . Second lever  232  is rigidly secured to control flap  216 . Mechanism  234  is configured to convert the motion of first lever  230  into a rotary motion of second lever  232  so that the second lever rotates control flap  216 . 
         [0031]    Advantageously, actuator  222  is configured to rotate control flaps  216 , but is sufficiently compact to fit into a confined space  248  defined by the exterior shape of rotor blade  212 . In this manner, actuator  222  minimizes and/or eliminates any portion of the actuator from protruding from confined space  248  during use so that the actuator does not effect the aerodynamics of rotor blade  212 , which enhances the effect of control flaps  216  on the airstream. 
         [0032]    Referring now to  FIG. 7 , a fourth exemplary embodiment of actuator  322  according to the present disclosure is shown in which component parts performing similar or analogous functions are labeled in multiples of three hundred. In a preferred embodiment, electric machine  324  is a direct current brushless motor and transmission device  328  includes a worm gear set  334  and a pair of bevel gears  336 . Worm gear set  334  steps down the speed and amplifies the torque of the rotary motion generated by motor  324 . The motion generated by transmission device  328  is transferred to control flap  316  through bevel gears  336 . In this particular configuration, worm gear set  334  is located in blade body  340  ahead of control flap  316 . Actuator  322  also includes a pair of links  338  connecting worm gear set  334  to control flap  316  so that motion from motor  324  is transmitted to control flap  316 . 
         [0033]    Advantageously, actuator  322  is configured to rotate control flaps  316 , but is sufficiently compact to fit into a confined space  348  defined by the exterior shape of rotor blade  312 . In this manner, actuator  322  minimizes and/or eliminates any portion of the actuator from protruding from confined space  348  during use so that the actuator does not effect the aerodynamics of rotor blade  312 , which enhances the effect of control flaps  316  on the airstream. 
         [0034]    Referring now to  FIG. 8 , a fifth exemplary embodiment of actuator  422  according to the present disclosure is shown in which component parts performing similar or analogous functions are labeled in multiples of four hundred. In a preferred embodiment, transmission device  428  includes a worm gear set  434  and a pair of bevel gears  436  where worm gear  434  is aligned with the rotational axis of control flap  416 . Thus, there is no additional connection mechanism necessary because transmission device  428  is capable of transmitting the rotary motion generated by electric machine  424  directly to control flap  416 . The configuration of actuator  422  is especially advantageous because worm gear  436  is located closer to the leading edge  420  of rotor blade  412  which counters the center of gravity, reduces drag and improves the effectiveness of torque and motion transmission. 
         [0035]    Advantageously, actuator  422  is configured to rotate control flaps  416 , but is sufficiently compact to fit into a confined space  448  defined by the exterior shape of rotor blade  412 . In this manner, actuator  422  minimizes and/or eliminates any portion of the actuator from protruding from confined space  448  during use so that the actuator does not effect the aerodynamics of rotor blade  412 , which enhances the effect of control flaps  416  on the airstream. 
         [0036]    Each of the aforementioned embodiments and their alternate configurations feature a very small profile, a simple design and a high efficiency in motion and torque transmission. Actuators  22 ,  122 ,  222 ,  322 , and  422  are tailored to fit into the confined space defined by the rotor blade body. Each transmission device uses either a gear or a linkage mechanism that operates at an optimal angle of transmission such that maximum efficiency is achieved. It has been determined by the present disclosure that the simple gear train mechanism and the linkage mechanism are reliable and require low maintenance. 
         [0037]    While the present disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated, but that the disclosure will include all embodiments falling within the scope of the appended claims.