Patent Application
20200301463
A rotorcraft may include one or more rotor systems. One example of a rotor system is a main rotor system on the rotorcraft. A main rotor system may generate aerodynamic lift to support the weight of the rotorcraft in flight and may generate thrust to counteract aerodynamic drag and move the rotorcraft in forward flight. Another example of a rotorcraft rotor system is a tail rotor system. A tail rotor system may generate thrust in the same direction as the main rotor system's rotation to counter the torque effect created by the main rotor system and to keep the rotorcraft's fuselage aligned in a desired direction.
Rotorcraft have flight control systems that allow pilots to control the main and tail rotor systems. Flight control systems comprise a collection of mechanical linkages and equipment connecting cockpit controls, such as a collective, a cyclic, and rudder pedals, to flight control surfaces that allow a rotorcraft to be flown with precision and reliability. For example, the rotorcraft flight control system controls operation (e.g. pitch) of the rotor blades through a swash plate component. The rotorcraft's flight control system is critical to flight safety.
Embodiments are directed to a flight control device comprising a grip, a stick associated with the grip, and a gimbal. The gimbal comprises a spherical bearing coupled to the stick, a first plate having a first hole configured to receive a top portion of the spherical bearing, and a second plate having a second hole configured to receive a bottom portion of the spherical bearing, wherein the first plate and the second plate are configured to move relative to each other to apply a variable force against the spherical bearing. The first hole further comprises a first inner surface, and the second hole comprises a second inner surface. The variable force against the spherical bearing may be applied by mechanical interaction between the first and second inner surfaces and a surface of the spherical bearing.
The flight control device further comprises a clamping device coupled to the first plate and the second plate, wherein the clamping device is configured to move the first plate and the second plate relative to each other. The clamping device may comprise a knob portion configured to receive a bolt portion. The knob is positioned to apply a force against the first plate, and the bolt portion is positioned to apply a force against the second plate. Turning the knob portion in a first direction reduces a distance between the first plate and the second plate. Turning the knob portion in a second direction opposite the first direction increases the distance between the first plate and the second plate. The clamping device may be selected from a mechanical clamp, an electronic motor, and a hydraulic actuator.
The first plate and the second plate may be configured to remain in a generally parallel relationship as they move relative to each other. Alternatively, a first end of the first plate and a first end of the second plate may be configured to remain at a fixed distance from each other, and a second end of the first plate and a second end of the second plate may be configured to move relative to each other to apply a variable force against the spherical bearing.
The flight control device may further comprise a lever coupled to the spherical bearing at a position opposite to the stick. The lever may be configured to be coupled to a flight control linkage. The flight control device may further comprise a cyclic stop coupled to the second plate, and a bump stop coupled to the spherical bearing and the lever, wherein the cyclic stop and the bump stop are configured to limit a range of motion of the spherical bearing.
Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:
While the system 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 system to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present application as defined by the appended claims.
Illustrative embodiments of the system of the present application are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer'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.
In the specification, reference may be made to the spatial relationships between various components and to the spatial orientation of various aspects of components as the devices are depicted in the attached drawings. However, as will be recognized by those skilled in the art after a complete reading of the present application, the devices, members, apparatuses, etc. described herein may be positioned in any desired orientation. Thus, the use of terms to describe a spatial relationship between various components or to describe the spatial orientation of aspects of such components should be understood to describe a relative relationship between the components or a spatial orientation of aspects of such components, respectively, as the device described herein may be oriented in any desired direction.
A pilot may manipulate one or more pilot flight control devices in order to achieve controlled aerodynamic flight. Inputs provided by the pilot to the pilot flight control devices may be transmitted mechanically and/or electronically (e.g., via a fly-by-wire flight control system) to flight control systems. Flight control systems may represent devices operable to change the flight characteristics of the aircraft. Examples of flight control systems on rotorcraft 100 may include the control system operable to change the positions (e.g., pitch) of blades 120 and blades 160.
Rotorcraft 100 may feature at least three sets of pilot flight control devices: a collective control assembly, a cyclic control assembly, and a pedal assembly. Although examples discussed herein describe pilot flight controls such as cyclic control assemblies, collective control assemblies, and pedal assemblies, teachings of certain embodiments recognize that other pilot flight controls may be used. For example, in some embodiments, a tiltrotor aircraft may include a power control device, and a thrust control device.
In general, cyclic pilot flight controls may allow a pilot to impart cyclic motions on blades 120. Cyclic motions in blades 120 may cause rotorcraft 100 to tilt in a direction specified by the pilot. For tilting forward and back (pitch) and/or tilting sideways (roll), the angle of attack or pitch of blades 120 may be altered cyclically during rotation, creating different amounts of lift at different points in the cycle.
Collective pilot flight controls may allow a pilot to impart collective motions on blades 120. Collective motions in blades 120 may change the overall lift produced by blades 120. For increasing or decreasing overall lift in blades 120, the angle of attack or pitch for all blades 120 may be collectively altered by equal amounts at the same time resulting in ascents, descents, acceleration, and deceleration.
Anti-torque pilot flight controls may allow a pilot to change the amount of anti-torque force applied to rotorcraft 100. As explained above, blades 160 may provide thrust in the same direction as the rotation of blades 120 to counter the torque effect created by rotor system 110 and blades 120. Anti-torque pilot flight controls may change the amount of anti-torque force applied to change the heading of rotorcraft 100. For example, providing anti-torque force greater than the torque effect created by rotor system 110 and blades 120 may cause rotorcraft 100 to rotate in a first direction, whereas providing anti-torque force less than the torque effect created by rotor system 110 and blades 120 may cause rotorcraft 100 to rotate in an opposite direction. In some embodiments, anti-torque pilot flight controls may change the amount of anti-torque force applied by changing the pitch of blades 160, increasing or reducing the thrust produced by blades 160 and causing the nose of rotorcraft 100 to yaw in the direction of the applied pedal. In some embodiments, rotorcraft 100 may include additional or different anti-torque devices, such as a rudder or a NOTAR (no tail rotor) anti-torque device, and the anti-torque flight controls may change the amount of force provided by these additional or different anti-torque devices.
The gimbal assembly 230 has a first function to hold that flight control device 200 in place and to act as the rotation point for the device. The secondary purpose of gimbal assembly 230 is to control friction in the system, which appears to an operator as “stiffness” associated with moving grip 210 and stick 220. A friction knob 280 may be configured such that twisting friction knob 280 applies friction to gimbal assembly 230 so that movement of flight control device 200 requires more force. In one embodiment, clockwise movement around axis 290 increases the friction applied by gimbal assembly 230 to flight control device 200, while turning friction knob 280 counter-clockwise around axis 290 decreases the friction applied by gimbal assembly 230. Therefore, when the friction applied by gimbal assembly 230 is increased, grip 210 may become harder to move; and when the friction applied by gimbal assembly 230 is decreased, grip 210 may become easier to move.
There may be several reasons why an adjustment of the friction by gimbal assembly 230 is preferable. For example, a pilot of rotorcraft 100 (
Friction is applied to cyclic stick support 300 using friction knob 360. Friction knob 360 has a stem 361 with a threaded portion 362. End portion 363 of stem 361 abuts plate 364 and prevents stem 361 from being removed from cyclic stick support 300 when friction knob 360 is moved. Friction wedge 365 is treaded to match threaded portion 362. When friction knob 360 is turned, stem 361 and threaded portion 362 also turn. The rotating threads on portion 362 cause wedge 365 to move upward or downward depending on which direction knob 360 is turned. Friction wedge 365 has a sloped surface 366 that pushes against a sloped surface 321 of bearing wedge 322. As friction wedge 365 is moved upward, sloped surface 366 moves against sloped surface 321, which causes bearing wedge 322 to move to the right in
Even though the configuration of cyclic stick support 300 has its advantages, such as limiting the movement of flight control stick coupling 310, it may also have some potential disadvantages. One potential disadvantage may be local “stiff” spots due to the mechanical system. For example, because bearing housing 340 applies force against spherical bearing 320 only at regions 341 and 342 to create friction, this may effectively create an axis 370 that spherical bearing 320 can more freely rotate around. Therefore, friction created in this manner is uneven, with the friction in the longitudinal stick direction always higher than in the lateral direction. Moreover, this configuration may be ineffective at holding a minimum friction setting, and a maximum friction setting may not be high enough. Because there can be potential disadvantages to using the friction system illustrated in
Friction is applied to cyclic stick support 400 using friction knob 460. Friction knob 460 has a stem 461 with a threaded portion 462. End portion 463 of stem 461 abuts plate 464 and prevents stem 461 from being removed from cyclic stick support 400 when friction knob 460 is moved. Plate 465 is threaded to match threaded portion 462. When friction knob 460 is turned, stem 461 and threaded portion 462 also turn. The rotating threads on portion 462 cause plate 465 to move upward or downward depending on which direction knob 460 is turned. When friction knob 460 is turned to move plate 465 upward, then plate 465 causes end 453 of bottom plate 450 to also move upward toward end 443 of top plate 440. Spacer 470 holds end 444 of top plate 440 at a fixed distance from the corresponding end 454 of bottom plate 450. When end 453 of bottom plate 450 moves upward due to tightening of friction knob 460, the gap 421 between bottom plate 450 and top plate 440 is reduced. This movement also causes the inner walls 442, 452 of holes 441, 451 in top plate 440 and bottom plate 450, respectively, to clamp against spherical bearing 420 thereby creating friction.
The friction generated using the system illustrated in
Although a threaded knob 460 and bolt 462 are used to move the plates 440 and 450 closer together or farther apart in the example illustrated in
Plates 440 and 450 may be configured to remain in a generally parallel arrangement in some embodiments. For example, plates 440 and 450 may move on rails, pins, or guides, such as bolts 462 and 471, so that the plates maintain a parallel relationship as the distance between plates 440 and 450 changes. Alternatively, plates 440 and 450 may hinge or pivot around a fixed point, such as spacer 470, when a clamping force is applied so that the distance between one end 443, 453 of each plate varies as the other end 444, 454 of each plate maintains a constant distance. In other embodiments, springs may be used in cyclic stick support 400 to push plates 440 and 450 apart in opposition to the clamping force applied by clamping system 460-464. For example, springs may be provided at location 472 and/or in place of spacer 470 to provide a force opposite to clamping system 460-464 so that plates 440 and 450 move quickly and freely as friction is applied or reduced.
In various configurations, either plate 440 or plate 450 may be considered to be in a fixed location, such as attached to the floor or deck of a rotorcraft cockpit. For example, if plate 440 is attached to the cockpit floor, then clamping system 460-464 would have the effect of pulling plate 450 upward to increase friction forces on spherical bearing 420. Alternatively, if plate 450 is attached to the cockpit floor, then clamping system 460-464 would have the effect of pulling plate 450 downward to increase friction forces on spherical bearing 420.
Cyclic stick support 400 further comprises a cyclic stop 480 coupled to plate 450. Cyclic stop 480 may be an annular ring having a hollow center region defined by an inner wall 481. A spherical bump stop 482 is coupled to the spherical bearing 420 and lever 430. Cyclic stop 480 may limit the movement of cyclic stick support 400. When bump stop 482 hits inner wall 481 due to movement of spherical bearing 420, the inner wall 481 and bump stop 482 prevent spherical bearing 420 from further movement in that direction. This effectively limits the degree of freedom and range of motion available to a stick attached to flight control stick coupling 410 and/or to flight control linkages attached to lever 430.
Friction is applied to cyclic stick support 500 by adjusting a clamping force applied by bearing housing ring 540 to spherical bearing 520. Bearing housing ring 540 does not form a complete circle but has a gap 541 that is defined by edges 542 and 543. The inner diameter of bearing housing ring 540 can be reduced by closing gap 541—i.e., by moving edges 542 and 543 closer together. Reducing the inner diameter of bearing housing ring 540 would assert a clamping force on spherical bearing 520 thereby increasing the friction in cyclic stick support 500. Conversely, the inner diameter of bearing housing ring 540 can be increased by opening gap 541—i.e., by moving edges 542 and 543 farther apart. Increasing the inner diameter of bearing housing ring 540 reduces the clamping force on spherical bearing 520 thereby reducing friction.
In one embodiment, friction is applied using friction knob 560. Friction knob 560 has a stem 561 that passes through lugs 544 and 545 on bearing housing ring 540. Lugs 544 and 545 may be any bump, spur, tab, or projection that allow friction knob 560 and stem 561 to be connected to bearing housing ring 540. Lugs 544 and 545 may be integral components of bearing housing ring 540 or may be separate attachments to bearing housing ring 540. In one embodiment, lug 544 is threaded and lug 545 is unthreaded. In other embodiments, either lug 544 or lug 545 may be threaded. Jam nut 562 is attached to stem 561 at a point adjacent to lug 544. Nut 563 is attached to stem 561 at a point adjacent to lug 545.
Friction is controlled by turning knob 560, which causes lugs 544 and 545 to move toward each other or apart from each other. Movement of lugs 544 and 545 cause corresponding movement of edges 542 and 543 of bearing housing ring 540. The direction and degree to which lugs 544 and 545 move in response to turning knob 560 is determined by the direction and pitch of the threads in lug 544. In one embodiment, the threads are configured so that clockwise movement of knob 560 moves lugs 544 and 545 closer together. In this configuration, nut 563 presses up against unthreaded lug 545 causing the bearing housing ring clamp to close. Jam nut 562 on lug 544 may set a maximum amount that the bearing housing ring clamp can open, which also sets a minimum friction. As lugs 544 and 545 move together, the inner diameter of bearing housing ring 540 decreases, which applies a clamping force on spherical bearing 520 thereby generating friction.
The friction generated using the system illustrated in
Although a knob 560 and threaded lug 544 are used to adjust gap 541 and to move edges 542 and 543 relative to each other in the example illustrated in
In one embodiment, a flight control device comprises a grip, a stick associated with the grip, and a gimbal. The gimbal comprising a spherical bearing coupled to the stick, a first plate having a first hole configured to receive a top portion of the spherical bearing, and a second plate having a second hole configured to receive a bottom portion of the spherical bearing. The first plate and the second plate are configured to move relative to each other to apply a variable force against the spherical bearing. The first hole further comprises a first inner surface, and the second hole comprises a second inner surface. The variable force against the spherical bearing is applied by mechanical interaction between the first and second inner surfaces and a surface of the spherical bearing.
The flight control device may further comprise a clamping device coupled to the first plate and the second plate. The clamping device is configured to move the first plate and the second plate relative to each other. The clamping device may comprise a knob portion configured to receive a bolt portion, wherein the knob is positioned to apply a force against the first plate and the bolt portion is positioned to apply a force against the second plate, and wherein turning the knob portion in a first direction reduces a distance between the first plate and the second plate. Turning the knob portion in a second direction opposite the first direction increases the distance between the first plate and the second plate. The clamping device may be selected from a mechanical clamp, an electronic motor, and a hydraulic actuator.
The first plate and the second plate may be configured to remain in a generally parallel relationship as they move relative to each other.
In a further embodiment, a first end of the first plate and a first end of the second plate are configured to remain at a fixed distance from each other. A second end of the first plate and a second end of the second plate are configured to move relative to each other to apply a variable force against the spherical bearing.
The flight control device may further comprise a lever coupled to the spherical bearing at a position opposite to the stick. The lever may be configured to be coupled to a flight control linkage. A cyclic stop may be coupled to the second plate. A bump stop may be coupled to the spherical bearing and the lever, wherein the cyclic stop and the bump stop are configured to limit a range of motion of the spherical bearing.
In another embodiment, a flight control stick support comprises a spherical bearing coupled to a flight control stick, a first plate having a first hole configured to receive a top portion of the spherical bearing, a second plate having a second hole configured to receive a bottom portion of the spherical bearing, and a clamping device configured to move the first plate relative to and the second plate to apply a variable force against the spherical bearing.
The first hole may comprise a first inner surface, and the second hole may comprise a second inner surface. The variable force against the spherical bearing is applied by mechanical interaction between the first and second inner surfaces and a surface of the spherical bearing.
The clamping device may be configured to apply a variable amount of stiffness to the flight control stick.
The clamping device may comprise a knob portion configured to receive a bolt portion, wherein the knob is positioned to apply a force against the first plate and the bolt portion is positioned to apply a force against the second plate, and wherein turning the knob portion in a first direction reduces a distance between the first plate and the second plate. Turning the knob portion in a second direction opposite the first direction increases the distance between the first plate and the second plate.
The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized that such equivalent constructions do not depart from the invention as set forth in the appended claims. The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present invention.
