Abstract:
A damper includes a housing that forms a fluidly sealed cavity for receiving a fluid therein. The fluid is configured to change fluid properties as electrical energy is induced. An electrical subsystem provides electrical energy to the fluid, which is monitored with a control subsystem. The method includes inducing the fluid with electrical energy to change the dampening effects of the damper in real time.

Description:
BACKGROUND 
       [0001]    1. Field of the Invention 
         [0002]    The present application relates generally to damper systems, and more specifically, to damper systems for aircraft. 
         [0003]    2. Description of Related Art 
         [0004]    Dampers are well known in the art for effectively dampening adverse forces exerted on a structure. Rotary aircraft utilize dampers to dampen forces, e.g., lead/lag forces, exerted on the components of the rotor system via the rotor blades during flight. The dampers are typically manufactured with one or more elastomeric materials that are configured to dampen the forces. In some embodiments, the dampers could utilizes a plurality of fluid chamber in communication with each other, wherein movement of the damper means disposed within the damper causes the fluid carried within the chambers to pass through a common passage, which in turn dampens the adverse forces. 
         [0005]    It should be understood that rotary aircraft must undergo preflight preparations to “warm” the dampers prior to flight. Current methods to prepare the dampers for flight include operating the aircraft at non-flight conditions. The process exhausts considerable time, resulting in significant costs. 
         [0006]    Another problem associated with conventional dampers is the inability to change the spring rate of the damper in real time. For example, the aircraft operates at various flight conditions, which affects the damper&#39;s performance. In some cases, it is possible to fly outside the designed damper spring rate, thus greatly reducing the efficiency of the damper. 
         [0007]    Although the foregoing developments in dampers represent great strides, many shortcomings remain. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0008]    The novel features believed characteristic of the embodiments of the present application are set forth in the appended claims. However, the embodiments themselves, as well as a preferred mode of use, and further objectives and advantages thereof, will best be understood by reference to the following detailed description when read in conjunction with the accompanying drawings, wherein: 
           [0009]      FIG. 1  is a side view of a helicopter according to a preferred embodiment of the present application; 
           [0010]      FIG. 2  is a perspective view of a tiltrotor aircraft according to another preferred embodiment of the present application; 
           [0011]      FIGS. 3 and 4  are perspective views of a rotary system of  FIG. 1 ; and 
           [0012]      FIG. 5  is a cross-sectional view of the damper of  FIG. 3  and a damper system in accordance with the preferred embodiment. 
       
    
    
       [0013]    While the system and method of the present application is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular embodiment disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the process of the present application as defined by the appended claims. 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0014]    Illustrative embodiments of the apparatus and method are provided below. It will of course be appreciated that in the development of any actual embodiment, numerous implementation-specific decisions will be made to achieve the developer&#39;s specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure. 
         [0015]    The system and method of the present application overcome the above-listed problems commonly associated with conventional dampers. Specifically, the system includes a damper associated with a heater for providing heat to the dampening means disposed within the damper. This feature greatly reduces the time exhausted for preparing the aircraft for flight. The system is further provided with fluid configured to change viscosity as electrical energy is received, which in turn changes the damper spring rate. This feature allows real time regulation of the damper spring rate for optimal performance during flight. Further detailed description of these features are provided below and illustrated in the accompanying drawings. 
         [0016]    The system and method of the present application will be understood, both as to its structure and operation, from the accompanying drawings, taken in conjunction with the accompanying description. Several embodiments of the system are presented herein. It should be understood that various components, parts, and features of the different embodiments may be combined together and/or interchanged with one another, all of which are within the scope of the present application, even though not all variations and particular embodiments are shown in the drawings. It should also be understood that the mixing and matching of features, elements, and/or functions between various embodiments is expressly contemplated herein so that one of ordinary skill in the art would appreciate from this disclosure that the features, elements, and/or functions of one embodiment may be incorporated into another embodiment as appropriate, unless described otherwise. 
         [0017]    Referring now to the drawings wherein like reference characters identify corresponding or similar elements throughout the several views,  FIG. 1  depicts an aircraft  101  in accordance with a preferred embodiment of the present application. In the exemplary embodiment, aircraft  101  is a helicopter having a fuselage  103  and a rotor system  105  carried thereon. A plurality of rotor blades  107  is operably associated with rotor system  105  for creating flight. 
         [0018]    Although shown associated with a helicopter, it will be appreciated that the damper system of the present application could also be utilized with different types of rotary aircraft and vehicles. For example,  FIG. 2  illustrates a tiltrotor aircraft  201  that utilizes the damper system in accordance with the present application. 
         [0019]    Tiltrotor aircraft  201  includes rotor assemblies  213   a  and  213   b  that are carried by wings  215   a  and  215   b , and are disposed at end portions  216   a  and  216   b  of wings  215   a  and  215   b , respectively. Tilt rotor assemblies  213   a  and  213   b  include nacelles  220   a  and  220   b , which carry the engines and transmissions of tilt rotor aircraft  201 , as well as, rotor proprotors  219   a  and  219   b  on forward ends  221   a  and  221   b  of tilt rotor assemblies  213   a  and  213   b , respectively. Tilt rotor assemblies  213   a  and  213   b  move or rotate relative to wing members  215   a  and  215   b  between a helicopter mode in which tilt rotor assemblies  213   a  and  213   b  are tilted upward, such that tilt rotor aircraft  201  flies like a conventional helicopter; and an airplane mode in which tilt rotor assemblies  213   a  and  213   b  are tilted forward, such that tilt rotor aircraft  201  flies like a conventional propeller driven aircraft. 
         [0020]      FIGS. 3 and 4  depict perspective views of rotor system  105  having a yoke  301  rotatably attached to rotor blade  107 . A damper  303  is shown operably attached to both yoke  301  and blade  107 . During operation, damper  303  dampens the forces exerted on the yoke via the blade. 
         [0021]    In the exemplary embodiment, damper  303  is shown operably associated with the rotor system; however, it will be appreciated that the features of the damper system discussed herein could also be utilized on one or more different systems and devices of the aircraft and should not be narrowly construed as limited to rotor systems. 
         [0022]    Damper  303  includes a dampening device  304  configured to dampen forces exerted against damper  303 , which in the preferred embodiment, is a piston  305  disposed within a housing  307  and situated between two fluid chambers  309  and  311 . A passageway  312  extending through the thickness of piston  305  provides fluid communication between the two chambers. In the exemplary embodiment, three elastomeric seals  313 ,  315 , and  317  are utilized to secure piston  305  to an inner surface  319  of housing  307 . 
         [0023]    Damper  303  is shown pivotally attached to yoke  301  via a piston rod  321 , and pivotally attached to rotor blade  107  via a fastener  323  that attaches to housing  307 . 
         [0024]    During operation, the elastomeric materials and fluid passing between the two chambers operate to dampen the forces exerted on the rotor yoke via the rotor blade, as depicted with arrow “D” in the drawings. In the illustrative embodiment, damper  303  is configured to reduce lead/lag forces of the rotor blade. Of course, it will be appreciated the features discussed herein could be incorporated on other types of dampers that dampen different forces in lieu of the preferred embodiment. 
         [0025]      FIG. 5  depicts a damper system  501  in accordance with the preferred embodiment of the present application. Damper system  501  includes one or more of a heater  503 , a sensor  505 , an electrical subsystem  507 , and a control subsystem  509 ; all being operably associated with damper  303 . 
         [0026]    Heater  503  is configured to provide heat energy, for example, provide heat energy to the elastomeric material and to the fluid of damper  303 . In the contemplated embodiment, heater  503  includes a plurality of coils  511  disposed within chamber  311 ; however, it will be appreciated that alternative embodiments could include other types of heating means positioned within the chamber. 
         [0027]    One unique feature believed characteristic of the present application is warming the components of the damper with heat energy from the heater prior to flight. This feature greatly reduces the time and costs associated with preparing the aircraft for flight. It should be appreciated that these features overcome the problems commonly associated with conventional damper systems. 
         [0028]    Electrical subsystem  507  is configured to provide electrical energy to the fluid disposed within damper  303 . In the contemplated embodiment, electrical subsystem  507  is positioned within chamber  309  and conductively coupled to an electrical energy source  513 . During operation, the electrical subsystem  507  induces electrical energy in the fluid. To achieve this feature, fluid  515  is an electrorheological fluid that changes in viscosity as electrical energy is added “induced.” 
         [0029]    Another unique feature believed characteristic of the present application is changing the spring rate of damper  303  in real time by changing the viscosity of the fluid by utilizing the electrorheological fluid and the electrical subsystem  507 . Thus, the damper allows selective controlling of the spring rate in real time according in accordance with different flight conditions. This feature overcomes the problems commonly associated with dampers, for example, dampers having a single spring rate. 
         [0030]    In the contemplated embodiment, sensor  505  is operably associated with both heater  503  and electrical subsystem  507  for sensing energy output and operation of damper  303 , and is configured to relay the sensed data to control subsystem  509 . The control subsystem  509  then either autonomously or manually regulates to heat and/or electrical input, thereby warming the components of damper  303  and/or changing the spring rate by regulating the electrical energy. 
         [0031]    It is apparent that a system and method with significant advantages has been described and illustrated. The particular embodiments disclosed above are illustrative only, as the embodiments may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. It is therefore evident that the particular embodiments disclosed above may be altered or modified, and all such variations are considered within the scope and spirit of the application. Accordingly, the protection sought herein is as set forth in the description. Although the present embodiments are shown above, they are not limited to just these embodiments, but are amenable to various changes and modifications without departing from the spirit thereof.