JP2015507158A - Rotary actuator - Google Patents

Abstract

A reference structure 110, an output member 113 arranged for rotational movement relative to the reference structure, and an output for moving the first motor member 119 and the second motor member 122 away from each other along a generally linear direction. A first linear motor 116 arranged and arranged to selectively apply and configured and arranged to cause torque between the output member and the reference structure in a first direction, generally along a linear direction Arranged to selectively apply an output that moves the first member 134 and the second motor member 137 of the second linear motor away from each other and in a direction opposite to the first direction, A rotary actuator 100 is provided having a second linear motor 137 configured and arranged to cause torque with the structure.

Description

  This application claims priority from US Provisional Patent Application No. 61 / 597,141, filed February 9, 2012, which is incorporated herein by reference.

  The present invention relates generally to the field of rotary actuators, and more specifically to high performance miniature rotary actuators.

  In general, several types of rotary actuators are known. For example, vane-based rotary hydraulic actuators are produced similar to pure electric motor-based rotary actuators.

  With reference to the bracketed symbols corresponding to parts, portions, or surfaces of the disclosed embodiment for purposes of illustration and not limitation, reference structure (110) and rotation relative to the reference structure about an axis. A first linear motor (116) having an output member (113) and a first member (119) and a second member (122) arranged to perform movement, generally along a linear direction Configured and arranged to selectively apply an output to move the first member and the second member away from each other, the first member of the first linear motor being coupled to the reference structure, The second member of the linear motor is coupled to the output member so that when the first linear motor applies an output, the first member moves between the output member and the reference structure about the axis in the first direction. Configured and arranged to cause torque at A first linear motor (116) and a second linear motor (131) having a first member (134) and a second member (137), generally along a linear direction Configured and arranged to selectively apply an output for moving a first member of a second linear motor and a second member of a second linear motor that are separated, and a first of the second linear motor The second member of the second linear motor is coupled to the output member, and when the output of the second linear motor is applied, the first member around the axis is coupled to the reference structure. A rotary actuator (100) having a second linear motor (131) constructed and arranged to cause torque between the output member and the reference structure in a direction opposite to the direction of Is done.

  The first linear motor (216) may comprise a single acting hydraulic motor. The first member of the first linear motor can have a prismatic chamber and / or the second member of the first linear motor can have a piston (222). The prismatic chamber may be a cylinder (219). The first linear motor can have a piston link (248) disposed between the piston and the output member. The first member of the first linear motor can be rigidly attached to the reference structure. The piston link and / or the piston may be connected through a ball joint. The piston link and output member may be connected through a pivot joint (228) or pin joint. Each of the first linear motor and the second linear motor can have a direction of action that can be generally parallel. The output member can have a shaft. The output member may include a first pivot bearing (228) coupled to a second member of the first motor and / or a second pivot bearing (240) coupled to a second member of the second motor. ). The first pivot bearing and the second pivot bearing may be separated by a predetermined offset in a dimension parallel to the axis.

  The first pivot bearing, the second pivot bearing, and the axis may be collinear. The first member of the first linear motor can have a cylinder, the second member of the first linear motor can have a piston, and the piston has a first surface and a second surface. Have. The first surface can form a first chamber (245) with the cylinder and the second surface can form a second chamber (255) with the cylinder. The cylinder can have a generally cylindrical surface. The cylindrical surface can have a hole between the first surface of the piston and the second surface of the piston. The rotary actuator can further have a drive link coupled to the piston. The drive link may cross the hole.

  The second linear motor (231) can comprise a single acting hydraulic motor. The first linear motor and the second linear motor, which are displaced by the predetermined linear motor operating linear distance, can have the same amount of hydraulic oil. The first linear motor and the second linear motor can be balanced by hydraulic pressure. The output member may be coupled to the aircraft control wing surface. The rotary actuator can further include a position sensor configured and arranged to measure the angle between the output member and the reference structure. The rotary actuator can further have a servo controller.

  In another aspect, an actuator (300) is provided that rotates a shaft (313) about an axis (319). The actuator (300) includes a housing (303), a first single acting cylinder (322) disposed in the housing, and having a first piston (328) and a first connecting link (349) therein. A crank (334) attached to the axis, and a second single-acting cylinder (325) disposed in the housing and having a second piston (331) and a second connecting link (349) therein. Have. Here, the first and second connecting links may be mounted at different locations on the crank, and the actuator is configured such that the operation of the first single acting cylinder causes the crank to rotate in the first direction, and The crank is configured and arranged to rotate in a second direction opposite to the first direction by operation of the second single-acting cylinder.

  The first and second cylinders may be oriented substantially parallel. Both the first and second cylinders may be configured and arranged such that each has a preload that applies force in the same general direction to eliminate backlash. The shaft can rotate on a set of bearings disposed within the housing. The shaft can be coupled to the aircraft control surface. The actuator may be configured and arranged to move the crank from the first position to the second position by applying additional pressure to one of the first pressure chamber and the second pressure chamber. . The actuator may be configured and arranged such that the crank position can be maintained by applying substantially equal pressure in the first and second pressure chambers.

  The actuator can be configured and arranged to maintain the crank position by preventing hydraulic fluid from flowing into or out of the first pressure chamber or the second pressure chamber. The first and second single acting cylinders may have a cross section that may not be circular. The first connecting link may be connected to the first piston through a ball joint (352). The first connecting link and the output member can be connected through a pivot joint or a pin joint. The first and second single acting cylinders may be separated by a predetermined offset in a dimension parallel to the axis. The first and second single acting cylinders can share a common bore. Configuring and arranging the actuator such that the first single acting cylinder releases an amount of hydraulic oil substantially equal to the amount of hydraulic oil drawn by the second single acting cylinder to move the shaft; Can do. The actuator can further include a position sensor arranged and configured to measure the angle between the shaft and the housing. The actuator can further have a servo controller.

  In another aspect, a reference structure (110), an output member (113) arranged for rotational movement relative to the reference structure about an axis, a first member (119) and a second member A first linear motor (116) having (122) configured and arranged to selectively apply an output to move the first member and the second member away from each other along a generally linear direction. The first member of the first linear motor is coupled to the reference structure, the second member of the first linear motor is coupled to the output member, and the first linear motor applies the output. A first linear motor (116) configured and arranged to cause torque between the output member and the reference structure about the axis in a first direction; and a first member (134) and second member (137) A second linear motor (131) that selects an output that moves the first member of the second linear motor and the second member of the second linear motor away from each other generally along a linear direction; The first member of the second linear motor is coupled to the reference structure, and the second member of the second linear motor is coupled to the output member, A second linear motor configured and arranged to cause torque between the output member and the reference structure in a direction opposite to the first direction about the axis when the output of the two linear motors is applied; A first non-zero force applied to the first linear motor and a second non-zero to the second linear motor. Force the power of the Comprising the step which can reduce the rush is provided.

  The method includes receiving a requested output member property and, when the output member has an actual property that does not match the requested output member property, the first non-zero force into a second non-zero force. The method may further comprise a step of adjusting for. The output member characteristic may be an angle with respect to the reference structure. The method increases the second non-zero force relative to the first non-zero force when the output member has an angle that is less than the requested angular position of the output member, thereby The method may further include a step capable of applying a torque to the reference structure.

  In another aspect, a cylinder (419) having a generally cylindrical inner surface about a longitudinal axis, a first end, and a second end, the inner surface being connected to the first end. A cylinder (419) having a hole (470) disposed between the second end and a piston (422) configured and arranged for sliding movement within the cylinder, wherein A first surface and a second surface, wherein the first surface and the second surface are opposed in a generally opposite direction along the longitudinal axis, the first surface together with the cylinder defining the first chamber (494). A piston (422), a first hydraulic port (492) in fluid communication with the first chamber, a second chamber, and a second surface forming a second chamber (495) with the cylinder A second hydraulic port (493) in fluid communication; And a second end, and a drive link (448) disposed through the hole, wherein the first end of the drive link has a first surface and a second end. A hydraulic actuator (400) having a drive link (448) coupled to a position on the piston between the surface and the actuator when the piston moves relative to the cylinder. A hydraulic actuator (400) is provided that may be configured and arranged to cause movement of the link.

  The drive link does not pass through the first chamber or the second chamber. The hydraulic actuator is between the reference structure and the drive link and the reference structure configured and arranged to allow rotational movement between the drive link and the reference structure about the axis. And a pivot joint. The cylinder can be attached to the reference structure. The hydraulic actuator can further include a drive shaft (413) configured and arranged to provide rotational movement with respect to the cylinder. A drive shaft can be coupled to the drive link. The cylinder can have a non-circular cross section. The drive link may be coupled to the piston through a pivot joint or pin joint. The drive link may be coupled to the piston through a universal joint. The drive link may be coupled to the piston through a ball joint. The first chamber and the second chamber can be balanced by hydraulic pressure.

  The actuator may be configured and arranged such that the first chamber releases an amount of hydraulic oil substantially equal to the amount of hydraulic oil drawn by the second chamber to effect piston movement relative to the cylinder. it can. The hydraulic actuator may further comprise a position sensor configured and arranged to measure the angle between the drive link and the cylinder. The hydraulic actuator can further include a servo control device.

  In another aspect, an oblique hydraulic pump (740) having a first hydraulic port (733), a second hydraulic port (735) and an input drive shaft, and an input drive shaft for the oblique pump Actuator assembly having a mechanically coupled gear shaft having a gear shaft for providing a mechanical advantage to rotate the oblique pump at a slower speed than the gear shaft (750) A system is provided, where the actuator power system can be configured and arranged to cause fluid flow between the first hydraulic port and the second hydraulic port when the gear shaft is rotatable. is there. The actuator power system can further include an electric motor (760) coupled to the gear shaft. The actuator power system can further include a hydraulically balanced rotary actuator that is constructed and arranged to receive power from the oblique axis hydraulic pump.

It is a side view of the 1st example of a rotary actuator. It is a side view of 2nd Example of a rotary actuator. FIG. 6 is a perspective view of a third embodiment of a rotary actuator. FIG. 4 is a front view of the rotary actuator shown in FIG. 3. FIG. 4 is a side view of the rotary actuator shown in FIG. 3. FIG. 4 is a perspective view of the embodiment shown in FIG. 3 with the case removed. FIG. 7 is a front view of the embodiment shown in FIG. 6. FIG. 7 is a side view of the embodiment shown in FIG. 6. FIG. 7 is an elevation view of the piston and connecting rod assembly of the rotary actuator shown in FIG. 6. It is sectional drawing by line 10A-10A of FIG. FIG. 10B is an exploded perspective view of a portion of the assembly shown in FIG. 10A. FIG. 13 is a side cross-sectional view of a fourth embodiment of a rotary actuator taken along line 11-11 in FIG. It is a front view of the 4th example of a rotary actuator. FIG. 13 is a perspective view of the piston assembly of the rotary actuator shown in FIG. 12. FIG. 14 is a side sectional view of the piston assembly shown in FIG. 13. It is an enlarged view of the site | part enclosed with the broken-line circle | round | yen shown by FIG. It is a front view of 5th Example of a rotary actuator. It is side surface sectional drawing of the rotary actuator shown by FIG. FIG. 6 is an isometric view of an alternative piston assembly. FIG. 19 is a top view of the alternative piston assembly shown in FIG. 18. FIG. 19 is a side view of the alternative piston assembly shown in FIG. FIG. 19 is a side cross-sectional view of the alternative piston assembly shown in FIG. FIG. 6 is a side view of another embodiment of the rotary actuator with the case removed. It is a systematic diagram of a rotary actuator system. FIG. 24 is a cross-sectional view of the first version of the pump shown in FIG. 23.

  Initially, like reference numerals are intended to consistently identify the same structural element, portion, or surface throughout the drawings, and the element, portion, or surface is further described or described throughout the specification. This detailed description of which can be an integral part. Unless otherwise specified, the drawings are intended to be read with the specification (eg, cross-hatching, component placement, proportions, degrees, etc.) and considered as part of the overall written description of the invention. Should be done. The terms “horizontal”, “vertical”, “left”, “right”, “upper”, and “lower”, as well as their adjective and adverb forms (for example, , “In the horizontal direction”, “in the right direction”, “upward”, etc.) simply refers to the orientation of the illustrated structure when the particular drawing faces the reader. Similarly, the terms “inward” and “outward” generally refer to the orientation of the surface relative to its extension or rotation axis, as appropriate.

  The disclosed embodiment provides a high performance rotary actuator and rotary actuator system driven by a linear motor. Referring now to the drawings, and more particularly to FIG. 1, a side view of a first embodiment of a rotary actuator is disclosed. The rotary actuator 100 includes a reference structure 110, a first linear motor 116, a second linear motor 131, and an output member 113. As shown in FIG. 1, the reference structure 110 is generally a ramen or a housing. The output member 113 is also generally rigid. Output member 113 is coupled to reference structure 110 through pivot joint 114. Pivot joint 114 allows rotational movement between reference structure 110 and output element 113 about axis 115 (axis 115 shown in FIG. 1 has a direction perpendicular to the page). The pivot joint 114 also includes a sensor that measures the angle and / or torque between the reference structure 110 and the output member 113.

  The linear motor 116 has two main parts including a first member 119 and a second member 122. The first member 119 and the second member 122 are coupled to perform a linear motion with respect to each other. When the linear motor 116 is activated, a force is applied to move the first member 119 and the second member 122 away from each other along the direction 160.

  The linear motor 131 is the same as the linear motor 116. The linear motor 131 has two main parts, a first member 134 and a second member 137. The first member 134 and the second member 137 are coupled to perform a linear motion with respect to each other. When the linear motor 131 is operated, a force is applied to move the first member 134 and the second member 137 away from each other along the direction 163.

  The first member 119 of the linear motor 116 is coupled to the reference structure 110 at the coupling 125. Second member 122 is coupled to output member 113 at coupling 128. Couplings 125 and 128 can include pivot joints, universal joints, or ball joints. Couplings 125 and 128 may be rigid attachments when a portion of first member 119 and second member 122 are rotatable relative to each other. The linear motor 116 is actuated to move the second member 122 so that it is driven to the right with respect to the first member 119 along the line 160. By this operation, the coupling 125 and the coupling 128 are effectively separated. Stated another way, the linear motor 119 causes a force applied between the reference structure 110 at location 125 and the output member 113 at location 128 in the direction in which the two are separated. Since the coupling 128 is above the line 165 formed between the coupling 125 and the pivot joint 114, the force applied by the linear motor 116 is between the reference structure 110 and the output member 113. Torque 169 is caused.

  The linear motor 131 is similarly connected between the reference structure 110 and the output element 113, but the linear motor 131 is the torque 169 applied between the reference structure 110 and the output element 113. Arranged to selectively cause torque 166 in the opposite direction. More specifically, the first member 134 of the linear motor 131 is coupled to the reference structure 110 at the coupling 143. Second member 137 is coupled to output member 113 at coupling 140. Couplings 143 and 140 can include pivot joints, universal joints, ball joints, or rigid attachments when portions of first member 134 and second member 137 are rotatable relative to each other. It may be. The linear motor 131 is operated to move the second member 137 so as to be driven in the right direction with respect to the first member 134. By this operation, the coupling 143 and the coupling 140 are effectively separated. Stated another way, the linear motor 131 causes a force applied between the reference structure 110 at location 143 and the output member 113 at location 140 in the direction in which the two are separated. Since the pivot joint 140 is below the line 167 formed between the coupling 143 and the pivot joint 114, the force applied by the linear motor 131 is between the reference structure 110 and the output member 113. Torque 166 is caused.

  Since the pivot joint 140 is below the line 167 compared to the pivot joint 128 above the line 165, the torques 166, 169 applied by each linear motor are in opposite directions. The linear motors 116 and 131 need only be able to provide a force in one direction between the reference structure 110 and the output element 113. It is not required that the linear motors 116 and 131 can provide both directions, ie "push" and "pull" forces. It is only necessary that the linear motors 116 and 131 are arranged so as to cause a torque in the opposite direction applied between the reference structure 110 and the output element 113. Although only a single-acting linear motor is required for the rotary actuator 110, a double-acting linear motor can be used in the rotary actuator 110 without departing from the spirit of the present invention. Also, since linear motors 116 and 131 will still be able to provide opposing torques, both motors are single acting linear motors that provide only a “pull” force instead of a “push” force. Can be replaced.

  Linear motors 116 and 131 may be electric motors, single acting hydraulic actuators, pneumatic actuators, linear drive screws, or some other similar motor type. The rotary actuator 110 can also include a servo controller.

  The rotary actuator 100 can be operated in a plurality of different modes of operation. The first method of operation is the low backlash mode. In the low backlash mode, a minimum threshold force is always applied by each linear motor 116, 131 while the rotary actuator 100 is in use. Under this mode, any tolerances or “plays” in the joints 114, 125, 128, 140, and 143 are “biased” in their “play” area, since the mechanical linkage of the system is constantly pressurized. This effectively prevents backlash. For example, if the rotary actuator 100 is initially required to apply a clockwise torque to the output member 113 and then apply a counterclockwise torque, the mechanical linkage in the rotary actuator 100 will always be Due to the pressurization, there will be no significant backlash. More specifically, in order to apply clockwise torque 169 to output member 113, linear motor 116 may be required to apply a force of 20N, while linear motor 131 has a minimum of 10N. Required to apply threshold force. Therefore, the force of 10N is canceled out between the motors, and the reaction force of 10N passes through the mechanical link mechanism between the motors. Thus, since each element of the rotary actuator 100 is under pressure caused by the reaction force, none of the joints of the rotary actuator 100 will “sway” freely. Next, if the rotary actuator 100 is required to apply a counterclockwise torque 166, the linear motor 116 is required to apply a minimum threshold force of 10N while the linear motor 131 is 20N. It is required to apply the power of. This causes a net torque on the output member 113 and shifts from clockwise to counterclockwise, but all of the joints of the rotary actuator 100 remain pressurized. A typical prior art rotary actuator with a single-acting motor maintains all joints of its pressurized mechanical linkage when switching between clockwise and counterclockwise torque Cannot be damaged by backlash when individual mechanical linkage joints are switched from a pressurized and extended state.

  The rotary actuator 100 can also be operated in a low friction mode, where only one motor is running at a time. By preventing continuous stretching in the mechanical linkages that exist in low backlash mode operation, the friction generated at the joints of the individual linkages is reduced. Low friction mode operation helps reduce the wear rate of the joint and linear motor. Further, since each motor does not operate continuously, the efficiency can be increased by the low friction mode compared to the operation in the low backlash mode.

  Also, depending on the specific needs of the system at a certain time, the operating mode of the rotary actuator 100 can be selectively adjusted.

  FIG. 2 is a side sectional view of a second embodiment of the rotary actuator. The rotary actuator 200 includes main components of a reference frame 210, a first single-acting hydraulic motor 216, a second single-acting hydraulic motor 231, and an output member 213. The rotary actuator 200 is arranged to drive a driven member 250 that is rigidly coupled to the output member 213.

  The first hydraulic motor 216 has a cylinder 219 and a piston 222. The cylinder 219 is firmly attached to the reference frame 210. The piston 222 is constructed and arranged within the cylinder 219 so that it can slide left and right within the cylinder 219 and maintains a seal between the outer surface of the piston 222 and the cylindrical wall inside the cylinder 219. Piston 222 and cylinder 219 form a chamber 245 that is in fluid communication with hydraulic port 246. The piston 222 has a pivot joint 247 coupled to the left end of the connection link 248. The right end of the connecting link 248 is coupled to the output member 213 through the pivot joint 228.

  The output member 213 is coupled to the reference structure 210 through the pivot joint 214, which allows the output member 213 to rotate relative to the reference frame 210 about the axis 215. The pivot joint 214 has a rotary position sensor 217, which detects the angle between the reference frame 210 and the output member 213 and outputs this angle information at the output line 218. . The follower member 250 is rigidly coupled to the output member 213 and the pivot joint 214 so as to rotate with the output member 213 relative to the reference frame 210.

  The second hydraulic motor 231 includes a cylinder 234 that is firmly attached to the reference frame 210 and a piston 237. The piston 237 is constructed and arranged within the cylinder 234 so that it can slide left and right within the cylinder 234 and maintains a seal between the outer surface of the piston 237 and the cylindrical wall inside the cylinder 234. Piston 237 and cylinder 234 form a chamber 255 in fluid communication with hydraulic port 256. The piston 237 has a pivot joint 257 that is coupled to the left end of the connecting link 258. The right end of the connection link 258 is coupled to the output member 213 through the pivot joint 240.

  Ports 246 and 256 supply hydraulic oil to single acting linear hydraulic motors 216 and 231, respectively. The output caused by linear motors 216 and 231 is directly dependent on the fluid pressure at ports 246 and 256, respectively. The pressure at ports 246 and 256 can be controlled by standard hydraulic valves.

  The operation of the rotary actuator 200 is substantially the same as that of the rotary actuator 100. More practically, both the hydraulic motors 216 and 231 cause a different polarity torque applied between the reference structure 210 and the output member 213, respectively, between the reference structure 210 and the output member 213. Bringing "push" power. Similarly, in the operation of the rotary actuator 100, the motors 119 and 131 provide a relative torque between the reference structure 110 and the output member 113. Further, the rotary actuator 200 can be operated in the low backlash mode and the low friction mode similarly to the operation mode of the rotary actuator 100.

  The dimensions of the linear hydraulic motors 216 and 231 are substantially the same. More specifically, the cross-sectional area of the cylinder 219 is substantially the same as the cross-sectional area of the cylinder 234. With these dimensions, the amount of hydraulic oil that flows through the port 246 when the piston 222 is displaced in the right direction is the amount of hydraulic oil that flows into the port 256 when the piston 237 is displaced in the same right direction. Become equivalent. When the rotary actuator 200 is “centered” in the sense that the piston 222 is displaced to the same extent as the piston 237, the rotation of the output member 213 is substantially equivalent to the case where the piston 237 is displaced leftward. The piston 222 is displaced in the right direction. The property of “balanced displacement” of the rotary actuator 200 has a fairly positive implication for the overall hydraulic system used to drive the rotary actuator 200. With the exception of oil reservoirs, the total hydraulic pressure during operation in the hydraulic system generally remains constant in systems that have only “balanced and displaced” actuators, such as the rotary actuator 200, so that the efficiency of the system Will improve considerably. Compared to an unbalanced hydraulic system, the workability of the high pressure fluid is not lost each time the overall hydraulic pressure of the system is reduced.

  Turning to FIGS. 3-10, and initially referring to FIG. 3, the rotary actuator 300 of the third embodiment has a housing 303 formed with a body 306 surrounding a shaft 313 (best in FIGS. 6 and 8). It is shown). The shaft 313 may be attached to a bearing (not shown) at both ends, and may include an output member 316. The output member 316 may be integrally formed with or attached to the shaft 313. Thus, the output member 316 rotates about the central longitudinal shaft axis 319. The housing 303 also includes two cylinders 322 and 325 extending from the body 306. Cylinders 322 and 325 define a chamber for pistons 328 and 331 (shown in FIGS. 6 and 8). Pistons 328 and 331 have a circular cross section suitable for use in cylinders 322 and 325. The cylinders 322 and 325 in this embodiment are single acting hydraulic cylinders as will be described in detail below. Based on this disclosure, the term cylinder is used to describe a linear motor cylinder and is not intended to be limited to any particular shape, but other chambers that receive pistons of different shapes. One skilled in the art will appreciate that shapes are also suitable. For example, a cylinder may refer to a cylinder having a non-circular cross section or a cylinder having a generally prismatic shape. Cylinders 322 and 325 have longitudinal axes 323 and 324, respectively, disposed on opposite sides of shaft axis 319, as best shown in FIG.

  In FIG. 6, the housing 303 has been removed to clearly show the arrangement of the pistons 328 and 331. Pistons 328 and 331 are coupled to crankpins 334 and 337 disposed at opposite ends of the central longitudinal shaft axis 319. Accordingly, the downward movement of the piston 328 causes the shaft 313 to rotate counterclockwise about the axis 319 with respect to the orientation of FIG. 6, and the downward movement of the piston 331 causes the shaft 313 to rotate. Rotates clockwise about the axis 319 with respect to the orientation of FIG. As best shown in FIG. 5, the cylinders 322 and 325 can be mounted at different locations along the length of the shaft 313. Further, as best shown in FIG. 4, pistons 322 and 325 can be arranged 327 in a zigzag or offset manner relative to each other.

  The piston 328 has a substantially flat surface 340 at the first end 343 so that when the piston 328 is installed in the cylinder 322, the end wall of the pressure chamber is formed. Cylinder 322 is single acting because the portion of the chamber adjacent to surface 340 is the only portion exposed to the working fluid. Accordingly, only the piston 328 must be sealed against one pressure chamber, and the piston 328 and connecting rod 349 are not sealed at the second end 346. The connecting rod 349 is attached to the piston 328 by a ball and pin structure 352, described in more detail below. The support portions 362, 365 of the connecting rod 349 are connected to a crank pin 334 on the shaft 313, as will be described in more detail below. The piston 331 has a flat surface 332, is installed in the cylinder 331, and is connected to the crankpin 337 by a connecting rod 349, similar to the piston 328.

  Turning to FIG. 9, the piston 328 and connecting rod 349 are shown in more detail. The upper surface 340 of the piston 328 is exposed to the working fluid. Piston 328 has rings 350, 353 for sealing engagement and sliding within the cylinder, as is known to those skilled in the art. The connecting rod 349 has a pair of support portions 362 and 365 that extend downward and slightly outward with respect to the second ends 357 and 358. Supports 362 and 365 have openings 363 and 366 through which crankpins 334 or 337 are received. The openings 363, 366 typically comprise a bearing surface 367 (FIG. 10A), such as a bushing, as will be appreciated by those skilled in the art. Turning to FIG. 10A, the connecting rod 349 is coupled to the piston 328 by a pin 356 mounted in the sphere 359. The connecting rod 349 has an opening 354 for receiving the sphere 359. The sphere 359 has a central opening for receiving the pin 356. The piston 328 has a central axial opening 329 for receiving the first end 351 of the connecting rod 349, and the piston 328 is lateral to the piston axis 370 (indicated by arrow 369). A pair of lateral openings 364, 368 are disposed on either side of the piston 328 to receive the pins 356. The pin 356 passes through the opening in the sphere 359 and through the lateral openings 364 and 368 in the piston 328 and is fixed in place by the connecting member 373. As best shown in FIG. 10B, the connecting member 373 has a main portion 375 having a flange 377 at one end 379 and a cap 381 having a flange 383 at one end 385. When the two portions of the connecting member 373 are attached, the flanges 377, 383 prevent the pin 356 from sliding out of the sphere 359 and the lateral openings 364, 368 in the piston 328. The main portion 375 of the connecting member 373 has a longitudinal portion 387 extending in the direction of the longitudinal axis 388. The longitudinal portion 387 has a reduced width portion 389 located toward the end portion 390. The reduced width portion 389 extends to a finger-like portion 391 having the same width as the remainder of the longitudinal portion 387 relative to the portion 392 and then to an angled portion 393 that terminates at the end portion 390. A cylindrical portion 393 having an opening 396 is disposed around the cap 381. Ring 397 is formed on the opposite side of opening 396, and ring 397 terminates at end 399.

  A hollow pin 356 is installed on both sides of the piston 328 through the lateral openings 364, 368 and through the sphere 359, by placing the main part 375 of the connecting member 373 through the pin 356 and the cap 381 by the main part 375. It is fixed by attaching it to the end portion 390. When the cap 381 is engaged with the main portion 375, the direction of the finger-like portion 391 is shifted inward and then fitted into the opening 396, and the ring 399 is incorporated into the reduced width portion 389 on the main portion 375. It is.

  The ball and pin structure 352 described above provides a mechanical advantage and reduces the size and weight of the connecting rod 349 and pin 356. Pin 356 sends the force received from the pressure chamber into sphere 359, and sphere 359 sends the force from pin 356 into crankshaft 313. The use of spheres 359 instead of pivot joints allows for additional degrees of freedom useful for relieving stress from any misalignment.

  Other structures for joining the connecting rod 349 to the piston 328 may be suitable as will be apparent to those skilled in the art.

  The first, second and third embodiments provide several surprising advantages. The rotary actuators 100, 200 and 300 have the advantage that they can be selectively operated in a low backlash mode, which provides greater accuracy in controlling the output member. Further, since the operation in the low backlash mode is arbitrary, a precise operation by the operation in the low wear mode is possible instead.

  Furthermore, the rotary actuators 100, 200 and 300 have the advantage that the hydraulic actuator is balanced. More specifically, in a balanced hydraulic actuator system, an amount of hydraulic oil equivalent to the amount of fluid exiting the smaller chamber enters the expanding chamber. Having an actuator system with fluid and force balanced provides a number of advantages. A balanced hydraulic system results in greater hydraulic pump efficiency. Furthermore, it is possible to use a hydraulic pump such as an oblique axis type hydraulic pump that is more suitable for balanced hydraulic operation. In addition, since the servo control algorithm and the hydraulic control valve do not necessarily cause a difference in right / left force, it is possible to design a simpler servo control device with balanced force.

  The rotary actuators 100, 200 and 300 also have the advantage of having a very thin housing. More specifically, as shown in FIG. 7, the lateral width of the rotary actuator 300 is much smaller than similar prior art systems. Since the cylinders 328 and 331 are arranged so as to be shifted in a zigzag manner relative to each other, a thin actuator housing that is impossible when the cylinders 328 and 331 are not arranged in a zigzag manner is realized. Furthermore, the connecting rod 349 of each piston in the rotary actuator 300 is connected by a pivot joint of a double support (362 and 365 in FIG. 6) and has a high surface area, so that the ball joint (352) Very large forces can be applied without damaging the joint, and the lever can be made shorter and the housing can be made thinner.

  Further, since the linear actuator requires only a single action, the number of parts is small, and the design is cheaper and simpler than the double-acting linear actuator of the prior art. Single acting linear motors used in actuators 100, 200 and 300 also provide the advantage of having a low hydraulic leakage. More specifically, prior art double acting hydraulic pistons typically have a piston link through a high pressure chamber that operates on one side of the piston. Such prior art systems require a high pressure seal across the piston link surface, which is problematic to design and maintain and often leads to significant leakage. In the disclosed embodiment, only a high pressure seal is provided between the outer surface of the piston and the inner surface of the cylinder, so that a high level of hydraulic oil leakage, such as would occur in prior art piston link seals. There is no.

  FIGS. 11-15 provide aspects of a fourth embodiment of a rotary actuator. FIG. 11 is a side sectional view of the rotary actuator 400 taken along section line 11-11 in the front view of FIG. As shown in FIGS. 11 to 12, the rotary actuator 400 includes a housing 410, an output shaft 413, a cylinder 419, a piston 422, a connection link 448, and a plain bearing 447. FIG. 11 also shows a left end plate 490 and a right end plate 491. The end plate 490 has been removed in FIG.

  The housing 410 is formed from cast iron, steel, composite material, high strength plastic, or other similar material. The housing 410 provides a surface for bolting or mounting the actuator 400 to the reference structure. The cylinder 419 is formed as a through hole of the housing 410. The cylinder 419 has a generally hollow cylindrical shape with a first end 471 and a second end 472. Near the middle between the first end 471 and the second end 472, the upper wall of the cylinder 419 has a hole 470.

  Piston 422 is arranged and configured for sliding engagement within cylinder 419. As shown in FIG. 11, the piston 422 has a generally cylindrical shape with a generally rectangular prismatic region 401 cut into the cylinder. More specifically, as shown in the orientation of FIG. 11, the piston 422 has a generally shaped cylinder disposed on its side. The piston 422 has a left vertical circular end surface 473 having a diameter substantially similar to the inner diameter of the cylinder 419. When the clockwise outer periphery of the cylinder 422 is traced, the upper edge of the surface 473 is connected to the horizontal cylindrical surface 475. The horizontal cylindrical surface 475 has a ridge facing the cylinder 419 and is configured to maintain a seal between the piston 422 and the cylinder 419. Such a seal is ring-shaped and made of Teflon or some other similar material. The cylindrical surface 475 extends rightward and is connected to the annular vertical surface 476. Tubular vertical surface 476 extends down to a flat horizontal surface 477. A flat horizontal plane 477 extends to the right and connects to a semi-cylindrical surface 478 having a cylindrical axis oriented perpendicular to the page, as shown in FIG. Surface 478 initially extends back, then to the right, and back up to a flat horizontal plane 479. Surface 479 is parallel to surface 477 and in the same plane. Surface 479 extends rightward to annular vertical surface 480. The annular surface 480 has an outer diameter. This outer diameter is substantially equal to the diameter of the cylinder 419. Surface 480 extends upward and connects to horizontal cylindrical surface 481. The horizontal cylindrical surface 481 also has a ridge facing the cylinder 419 and is configured to maintain a seal. Surface 481 extends rightward into vertical circular surface 474. Surface 474 extends downward and joins back to cylindrical surface 481 at 482. As shown in FIG. 11, 481 and 482 refer to the same cylindrical surface by a cut surface. The surface indicated by 481 and 482 is also the same surface as indicated by 475 and 483. The surface at 482 extends to the left to 483. The surface at 483 is in contact with the lower end of the vertical circular surface 473 and completes a clockwise outer periphery that rotates about the piston 422.

  Passing through the central region of the cylindrical surface 478 is a vertical through hole 485. A cylindrical sliding bearing 447 is disposed within the cylindrical surface 478 with close tolerances. The plain bearing 447 is a piston surface 478 in two degrees of freedom, including longitudinal sliding in and out of the page (as directed in FIG. 11) and rotation about the axis of the cylindrical surface 478. Slides freely against.

  The plain bearing 447 has a generally cylindrical shape with a cylindrical axis that is coaxial with the cylindrical axis of the surface 478. The slide bearing 447 has a cylindrical through-hole 486, which holds the lower end 448a of the rod-shaped connecting link 448 in sliding engagement. More specifically, the link 448 can slide relative to the sliding bearing 447 along line 487. The connecting link 448 extends through the through hole 470 where it connects to the output member 413 and continues to extend its upper end 448 b into the chamber 403. Chamber 403 is defined by the upper wall of housing 410, end plates 490 and 491, and the upper wall of cylinder 419. Chamber 403 is in fluid communication with hole 470, region 401, and fluid port 499 located on the top wall of housing 410.

  The output member 413 is disposed over the hole 470 and is coupled to the pivot joint 414. Pivot joint 414 allows output member 413 to rotate relative to housing 410 about axis 415 oriented perpendicular to the page as shown in FIG. The output member 413 has a cylindrical through-hole 488 that forms a sleeve around the link member 448 that holds the link 448 in close non-moving engagement. The pivot joint 414 is also coupled to the link 448 to cause movement of the link 448 that is limited to rotational movement about the axis 415.

  The end plates 490 and 491 are respectively disposed at the left and right ends of the cylinder 419 and attached to the housing 410. The hydraulic port 492 connects through the end plate 490 to the chamber 494 formed by the cylinder 419 and the piston surface 473. Similarly, hydraulic port 493 connects through end plate 491 to chamber 495 formed by cylinder 419 and piston surface 474. Around the upper end 448b of the link 448 is a sliding bearing 447 '. The sliding bearing 447 'is substantially similar to the sliding bearing 447 and is shown for illustrative purposes only in FIGS. Although this embodiment does not have a sliding bearing 447 ′, FIGS. 11-15 show how easily the sliding bearing 447 ′ can be added with a second piston that is symmetric with respect to the piston 422 in the chamber 403. Indicate.

  FIGS. 13-15 show aspects of the piston assembly shown in FIG. 11, which includes a piston 422, a connecting link 448, a pivot joint 414, and a plain bearing 447. Note that in FIGS. 13-15, the connecting link 448 is oriented vertically, whereas in FIGS. 11 and 12, the connecting link 448 is in a rotated configuration.

  Comparing the changes from FIG. 11 to FIG. 15, how the sliding bearing 447 is rotated counterclockwise, and the lower end 448 a of the connecting link slides downward with respect to the sliding bearing 447, and the bore 486. You can see penetrating into.

  The rotary actuator 400 generally operates by adjusting the hydraulic pressure in the ports 492 and 493 to move the piston 422 to the left or right, and then actuate the connecting link as a rotating lever, after which the output The link 413 is also rotated.

  Illustratively, consider the rotary actuator 400 in the state shown in FIG. 11 where it is desired to rotate the output member 413 counterclockwise. First, the ports 492 and 493 will be connected to the hydraulic control lines, the housing 410 will be attached to the reference structure, and the output shaft / link 413 will be a rotationally driven member. Will be linked. Then, the hydraulic pressure in the port 492 is increased, but the hydraulic pressure in the port 493 is decreased. This increases the pressure in chamber 494 and decreases the pressure in chamber 495. When the pressure in chamber 494 falls below the pressure in chamber 495, a net rightward force is effectively applied to piston 422. More practically, the pressure exerted by the fluid in chamber 494 provides a rightward force on cylindrical surface 473. A similar leftward force is provided by the pressure in chamber 495 on cylindrical surface 474. Because the pressure in 494 is greater than 495, the rightward force is greater than the leftward force, so that a net rightward force is applied to the piston 422. This force is effectively interposed on the piston 422 through the housing 410 and the end plates 490 and 491.

  The rightward force on the piston 422 is transmitted as a rightward force at the lower end of the connecting link 448a through the sliding bearing 447. Because the connecting link 448 is rigidly coupled to the output shaft 413 and the link 448 and the output shaft 413 are coupled to the pivot joint 414, the connecting rod 448 moves to rotate about the pivot joint 414. Is only possible. The rightward force applied to the connecting link 448 serves as a lever having a fulcrum at the pivot joint 414. Accordingly, the rightward force applied by the piston 422 is converted to counterclockwise torque on the connecting link 448 and then sent to the output shaft 413.

  Since the piston 422 slides to the right with respect to the housing 410, the connection link 448 rotates counterclockwise with respect to the housing 410. Since the connecting link 448 rotates counterclockwise, the lower end portion 448a of the link 448 must slide downward with respect to the sliding bearing 447. In other words, since the lower end 448a of the link must advance in an arc shape with respect to the pivot joint 414, the vertical height of the lower end 448a relative to the piston 422 always changes as the rotation angle of the connection link 448 changes. To do. In addition, since the connecting link 448 rotates counterclockwise with respect to the housing 410, the sliding bearing 447 always rotates counterclockwise with respect to the piston 422. This is because the connecting link 448 rotates with the sliding bearing 447. It is because it is surrounded by low tolerance.

  If there is any misalignment in the alignment between the connecting link 448, the piston 422 and the cylinder 419, the sliding bearing 447 is free to move into or out of the page shown in FIG. 11 to mitigate such misalignment. To slide. If the cylinder 419 is not completely orthogonal to the plane in which the connecting link 448 rotates, such as when the right end of the cylinder 419 is tilted slightly out of the page, the sliding bearing 447 will loosely contact the connecting link 448. Can be slid upward / downward as the piston 422 moves left and right.

  Since the cross-section of the cylinder 419 is the same on the left side of the piston 422 and the right side of the piston 422, the amount of fluid that should flow through the port 492 is the amount of fluid that flows out of the port 493 as the piston 422 moves to the right. Must be equal to the amount of. Therefore, the rotary actuator 400 is a hydraulic actuator that is balanced.

  A seal disposed between piston 422 and cylinder 419 at 475 and 481 prevents high pressure from chambers 494 and 495 from passing through regions 401 and 403. Thus, the output shaft 413 does not contact any high pressure chamber. Port 499 is used to supply oil that may need to be lubricated to output shaft 413 and connecting link 448 or to gradually drain any oil that leaks across the seal between piston 422 and cylinder 419. To do.

  FIGS. 18-21 illustrate a variation of the rotary actuator 400 having a second version of the piston assembly 505 in which a cylindrical slide bearing 447 is replaced with a spherical slide bearing 547. FIG. 18 is a perspective view of the second version of the piston assembly 505 showing the piston 522 holding the ball slide bearing 547 surrounding the connecting link 548. FIG. 19 is a top view of assembly 505 showing the placement of ball slide bearings 547 within piston 522. FIG. 20 is a side view of the piston assembly 505, and FIG. 21 is a cross-sectional side view taken along line 21-21 in FIG. As shown in FIG. 21, the ball slide bearing 547 is held in a two-dimensional rotational engagement with the piston 522 through the race 507. The race 507 is held in the piston 522 by a flanged annular end stop 506. The ball sliding bearing 547 allows the lower end 548a of the connecting link 548 to slide linearly in and out of the central through hole of the ball sliding bearing 547.

  The ball slide bearing 547 operates very similar to the cylindrical slide bearing 447 in the rotary actuator 400. However, as seen in FIG. 21, instead of providing a page inward and outward freedom for a piston such as a sliding bearing 447, the ball sliding bearing 547 is referred to as rotational movement between the ball sliding bearing 547 and the piston 522. Give two degrees of freedom. This second degree of freedom mitigates any misalignment of the connecting links 548, where the connecting links 548 are not perfectly positioned in the plane of the page shown in FIG.

  FIGS. 16-17 illustrate another embodiment of a rotary actuator similar to the rotary actuator 400 but having four cylinders and four pistons. FIG. 16 is a top view of actuator 600 with end plates removed showing parallel cylinders 619a, 619b, 619c, and 619d. 17 is a side cross-sectional view taken along line 17-17 in FIG. As shown in FIG. 17, pistons 622a and 622b are disposed in respective cylinders 619a and 619b. The piston 622a and the piston 622b are substantially symmetric about the axis of the pivot joint 614. When clockwise torque is desired at the output shaft 613, the piston 622a is driven to the right while the piston 622b is driven to the left. The drive pistons 622a and 622b of the hydraulic port may or may not be hydraulically coupled. When these pistons 622a and 622b are hydraulically coupled, the hydraulic phase adjustment becomes easier. If the pistons 622a and 622b are not hydraulically coupled and phase adjustment is more difficult, the system will allow for duplexing if one of the piston-cylinder pairs is compromised by hydraulic pressure. Although not shown, pistons 622c and 622d have a plane that is symmetrical to pistons 622a and 622b. All four pistons are coupled to the output shaft 613.

  Embodiments 400 and 600 have several surprising advantages over prior art rotary actuator systems. The rotary actuators 400 and 600 have the advantage of being balanced hydraulic actuators like the actuators 100, 200 and 300. For example, referring to FIG. 11, the amount of fluid entering chamber 494 is substantially equal to the amount of fluid exiting chamber 495 because piston 422 moves to the right. In prior art double-acting pistons having a piston rod through one chamber, the amount of fluid entering / exiting the piston rod side chamber is determined by the cross-sectional area of the piston rod, the fluid exiting / entering the chamber without the piston rod Less than. Furthermore, due to the cross-sectional area of the piston rod, the force applied to the piston for a certain oil pressure will be different on the piston side without the piston rod. Because the rotary actuator 400 does not have a piston rod that passes through the chamber 494 or 495, the magnitude of the force applied to the piston 422 for a constant pressure in the chamber 494 is applied by the chamber 495 to which an equivalent pressure is applied. It is equivalent to the force in the opposite direction to be applied. Having an actuator system with fluid and force balanced provides a number of advantages. A balanced hydraulic system results in greater hydraulic pump efficiency. Furthermore, it is possible to use a hydraulic pump such as an oblique axis type hydraulic pump that is more suitable for balanced hydraulic operation. In addition, since the servo control algorithm and the hydraulic control valve do not necessarily cause a difference in right / left force, it is possible to design a simpler servo control device with balanced force.

  Furthermore, the rotary actuators 400 and 600 have the advantage of being thin and having a small number of parts, as seen in the actuators 100, 200 and 300. The low profile allows these actuators to be used in thin wing aircraft designs or other environments that require low profile.

  As shown in FIG. 22, multiple rotary actuators 300 can be combined to drive the same output member 316 to achieve a high drive torque or fault tolerance / redundancy system. Actuators 300 are shown, but their housings are removed for clarity. The actuator shafts 313 of the two actuators 300 are connected to form a single unit that can be acted upon simultaneously by all four pistons.

  FIG. 23 illustrates an actuator system 700 that includes one or more rotary actuators 720 and an electro-hydraulic beveled pump system 730. System 700 also includes an oil reservoir 725 and a servo valve system 722. The pump 730 is specifically designed for efficient operation in a balanced hydraulic system.

  FIG. 24 shows a side cross-sectional view of an electrohydraulic oblique shaft pump system 730. The pump system 730 includes the major components of a housing 731 that holds each of the oblique shaft pump 740, the gear box 750, the electric motor 760, and other components together. Pump system 730 provides a pressure differential and fluid flow between hydraulic ports 733 and 735 when driven.

  Oblique shaft pump 740 includes piston heads 737a and 737b coupled to piston links 738a and 738b, respectively. Piston heads 737a and 737b are located in the pump main part supported by bearing 739. Piston links 738a and 738b are coupled to a rotor 744 suspended by bearings 741.

  The gear box 750 includes gears 751, 752, and 753. The gears 751, 752, and 753 are held in the housing 731. Gear box 750 is mechanically coupled to rotor 744. The motor 760 has an output shaft 761 that is coupled to the gear box 750. The motor 760 also has a stator 762 and a rotor 763. The gear box 750 is configured to provide a mechanical advantage that causes the oblique pump rotor to rotate at a slower speed than the motor shaft 761.

  The pump system 730 is particularly suitable for use with a balanced hydraulic actuator. Since the oblique shaft pump 740 has only two ports, in particular, a balanced hydraulic actuator that does not require the need for a third hydraulic port to increase or decrease the amount of hydraulic oil in the system. Suitable for In addition, the use of a gear box that provides mechanical advantage allows the pump system life to be extended, which is particularly appropriate for aircraft applications.

  The particular embodiment shown can also be combined with a servo controller. A linear motor to adjust the output force or position based on the required output member torque / position and the measured output member torque / position using standard servo controllers Can be controlled.

Accordingly, while preferred forms of the invention have been disclosed and described with respect to rotary actuators, rotary actuator systems, and methods of operating rotary actuators, and some modifications thereof have been described, those skilled in the art It will be readily appreciated that various additional changes may be made without departing from the spirit of the invention.

Claims (56)

A reference structure;
An output member arranged to perform a rotational motion relative to the reference structure about an axis;
A linear motor having a first member and a second member configured to selectively apply an output that moves the first member and the second member away from each other in a generally linear direction; A first linear motor disposed;
The first member of the first linear motor coupled to the reference structure;
The second member of the first linear motor coupled to the output member, and when the first linear motor applies the output, the output member and the center around the axis The second member of the first linear motor configured and arranged to cause torque in a first direction with respect to a reference structure;
A second linear motor having a first member and a second member, the first member of the second linear motor and the second member of the second linear motor generally A second linear motor constructed and arranged to selectively apply an output that moves away along a linear direction;
The first member of the second linear motor coupled to the reference structure;
The second member of the second linear motor coupled to the output member, and when the output of the second linear motor is applied, the output member and the center around the axis A rotary actuator comprising: a second member of the second linear motor configured and arranged to cause a torque with a reference structure in a direction opposite to the first direction.   The rotary actuator of claim 1, wherein the first linear motor comprises a single acting hydraulic motor.   The rotary actuator according to claim 2, wherein the first member of the first linear motor has a prismatic chamber, and the second member of the first linear motor has a piston.   The rotary actuator according to claim 3, wherein the prismatic chamber is a cylinder.   The rotary actuator of claim 3, wherein the first linear motor has a piston link disposed between the piston and the output member.   4. The rotary actuator of claim 3, wherein the first member of the first linear motor is rigidly attached to the reference structure.   The rotary actuator of claim 5, wherein the piston link and the piston are connected through a ball joint.   The rotary actuator of claim 5, wherein the piston link and the output member are connected through a pivot joint or a pin joint.   The rotary actuator of claim 1, wherein the first linear motor and the second linear motor each have a generally parallel direction of action.   The output member includes a shaft, a first pivot bearing coupled to the second member of the first motor, and a second pivot bearing coupled to the second member of the second motor. The rotary actuator according to claim 1.   The rotary actuator of claim 10, wherein the first pivot bearing and the second pivot bearing are separated by a predetermined offset in a dimension parallel to the axis.   The rotary actuator of claim 10, wherein the first pivot bearing, the second pivot bearing, and the axis are collinear.   The first member of the first linear motor has a cylinder, the second member of the first linear motor has a piston, and the piston has a first surface and a second surface. The rotary actuator of claim 1, wherein the first surface forms a first chamber with the cylinder and the second surface forms a second chamber with the cylinder.   The rotary actuator of claim 13, wherein the cylinder includes a generally cylindrical cylindrical surface, the cylindrical surface having a hole between the first surface of the piston and the second surface of the piston. .   The rotary actuator of claim 14, further comprising a drive link coupled to the piston and traversing the hole.   The rotary actuator of claim 2, wherein the second linear motor comprises a single acting hydraulic motor.   The rotary actuator of claim 16, wherein the first linear motor and the second linear motor have equal displacement hydraulic volumes for a predetermined linear motor operating linear distance.   The rotary actuator of claim 16, wherein the first linear motor and the second linear motor are balanced hydraulically.   The rotary actuator of claim 1, wherein the output member is coupled to an aircraft control surface.   The rotary actuator of claim 1, further comprising a position sensor configured and arranged to measure an angle between the output member and the reference structure.   The rotary actuator of claim 20, further comprising a servo controller. An actuator that rotates a shaft about an axis,
A housing,
A first single acting cylinder disposed within the housing and having a first piston and a first connecting link therein;
A crank disposed on the shaft;
An actuator having a second single-acting cylinder disposed in the housing and having a second piston and a second connecting link therein;
The first and second connecting links are mounted at different locations on the crank, and the actuator is arranged so that the crank rotates in a first direction by actuation of the first single acting cylinder. An actuator configured and arranged so that operation of a second single acting cylinder causes the crank to rotate in a second direction opposite to the first direction.   23. The actuator of claim 22, wherein the first and second cylinders are oriented substantially parallel.   23. The actuator of claim 22, wherein both the first and second cylinders are each configured and arranged to have a preload that applies a force in the same general direction to remove backlash. .   23. The actuator of claim 22, wherein the shaft rotates on a set of bearings disposed within the housing.   The actuator of claim 22, wherein the shaft is coupled to an aircraft control surface.   The actuator is configured and arranged to move the crank from a first position to a second position by applying additional pressure to one of the first pressure chamber and the second pressure chamber. The actuator according to claim 22.   28. The actuator of claim 27, wherein the actuator is configured and arranged to maintain the position of the crank by applying substantially equal pressure in the first and second pressure chambers.   The actuator is constructed and arranged to maintain the position of the crank by preventing hydraulic fluid from flowing into or out of the first pressure chamber or the second pressure chamber. Item 27. The actuator according to Item 27.   23. The actuator of claim 22, wherein the first and second single acting cylinders have a non-circular cross section.   23. The actuator of claim 22, wherein the first connection link is connected to the first piston through a ball joint.   23. The actuator of claim 22, wherein the first connection link and the output member are connected through a pivot joint or a pin joint.   23. The actuator of claim 22, wherein the first and second single acting cylinders are separated by a predetermined offset in a dimension parallel to the axis.   23. The actuator of claim 22, wherein the first and second single acting cylinders share a common bore.   The actuator is configured such that the first single-acting cylinder releases an amount of hydraulic oil substantially equal to the amount of hydraulic oil drawn by the second single-acting cylinder to move the shaft. 24. The actuator of claim 22, wherein the actuator is disposed.   23. The actuator of claim 22, further comprising a position sensor configured and arranged to measure an angle between the shaft and the housing.   37. The actuator of claim 36, further comprising a servo controller. A reference structure;
An output member arranged to perform a rotational motion relative to the reference structure about an axis;
A first linear motor having a first member and a second member for selectively applying an output that moves the first member and the second member away from each other along a generally linear direction. A first linear motor constructed and arranged in
The first member of the first linear motor coupled to the reference structure;
The second member of the first linear motor coupled to the output member, and when the first linear motor applies the output, the output member and the center around the axis The second member of the first linear motor constructed and arranged to cause torque in a first direction with respect to the reference structure;
A second linear motor having a first member and a second member, wherein the first member of the second linear motor and the second member of the second linear motor are in a generally linear direction. A second linear motor configured and arranged to selectively apply an output that moves away along the line;
The first member of the second linear motor coupled to the reference structure;
The second member of the second linear motor coupled to the output member, and when the output of the second linear motor is applied, the output member and the center around the axis A method of operating an actuator having a second member of the second linear motor constructed and arranged to cause torque in a direction opposite to the first direction with a reference structure. And
Causing the first linear motor to apply a first non-zero force and causing the second linear motor to apply a second non-zero force;
Thereby reducing backlash. Receiving the requested output member characteristics;
Adjusting the first non-zero force with respect to the second non-zero force when the output member has an actual characteristic that does not match the requested output member characteristic; 40. The method of claim 38.   40. The method of claim 39, wherein the output member property is an angle relative to the reference structure.   When the output member has an angle that is less than the required angular position of the output member, the second non-zero force is increased relative to the first non-zero force, thereby 41. The method of claim 40, further comprising the step of applying torque between the reference structure. A cylinder having a generally cylindrical inner surface with a longitudinal axis, a first end, and a second end;
The inner surface having a hole disposed between the first end and the second end;
A piston constructed and arranged to perform a sliding motion within the cylinder, the piston having a first surface and a second surface, the first surface and the second surface being in the longitudinal axis A piston generally facing in the opposite direction,
The first surface forming a first chamber with the cylinder, and the second surface forming a second chamber with the cylinder;
A first hydraulic port in fluid communication with the first chamber;
A second hydraulic port in fluid communication with the second chamber;
A drive link having a first end and a second end and disposed through the hole, wherein the first end of the drive link is connected to the first surface; A hydraulic actuator having a drive link coupled to a position on the piston between the second surface,
The actuator is constructed and arranged to cause movement of the drive link relative to the cylinder as the piston moves relative to the cylinder.   43. The hydraulic actuator of claim 42, wherein the drive link does not pass through the first chamber or the second chamber.   A reference structure and a pivot joint between the drive link and the reference structure to allow rotational movement between the drive link and the reference structure about an axis 43. The hydraulic actuator of claim 42, further comprising a pivot joint configured and arranged on the cylinder, wherein the cylinder is mounted to the reference structure.   43. The hydraulic actuator of claim 42, further comprising a drive shaft configured and arranged to provide rotational movement relative to the cylinder, wherein the drive shaft is coupled to the drive link.   43. The hydraulic actuator of claim 42, wherein the cylinder has a non-circular cross section.   43. The hydraulic actuator of claim 42, wherein the drive link is coupled to the piston through a pivot joint or pin joint.   43. The hydraulic actuator of claim 42, wherein the drive link is coupled to the piston through a universal joint.   43. The hydraulic actuator of claim 42, wherein the drive link is coupled to the piston through a ball joint.   43. The hydraulic actuator of claim 42, wherein the first chamber and the second chamber are hydraulically balanced.   The actuator is constructed and arranged such that the first chamber releases an amount of hydraulic oil substantially equal to the amount of hydraulic oil drawn by the second chamber to effect movement of the piston relative to the cylinder. 43. The hydraulic actuator of claim 42, wherein:   43. The hydraulic actuator of claim 42, further comprising a position sensor configured and arranged to measure an angle between the drive link and the cylinder.   53. The hydraulic actuator of claim 52, further comprising a servo controller. An oblique hydraulic pump having a first hydraulic port, a second hydraulic port and an input drive shaft;
A gear shaft mechanically coupled to an input drive shaft of the oblique shaft for providing a mechanical advantage that rotates the oblique pump at a slower speed than the gear shaft. An actuator power system having a gear assembly comprising:
An actuator power system constructed and arranged to cause fluid flow between the first hydraulic port and the second hydraulic port when the gear shaft is rotated.   55. The actuator power system of claim 54, further comprising an electric motor coupled to the gear shaft.   56. The actuator power system of claim 55, further comprising a hydraulically balanced rotary actuator configured and arranged to receive power from the oblique axis hydraulic pump.

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