Patent Application
20080054214
With reference to
As stated above the drive subassembly 204 includes the diaphragm subassembly 206 and the lever subassembly 208. The diaphragm subassembly 206 is attached to the housing 202 via the opening 228 in the cylindrical body 220. The cavity 232 defined by the housing 202 contains the lever subassembly 208.
The diaphragm subassembly 206 generally includes the diaphragm 210 and the diaphragm rod 212. Additionally, the diaphragm subassembly 206 includes a housing 234, a diaphragm plate 236, a first compression spring 2318, a second compression spring 240, a threaded fastener 242, and a rod end-bearing 243. The housing 234 includes an upper housing 234a and a diaphragm casing 234b secured together by a plurality of cap screws 244. The diaphragm casing 234b defines an inlet port 245 adapted to be connected to a pressure source such as a pneumatic line. The upper housing 234a is generally cup-shaped and includes a lower shelf portion 246 and an upper shelf portion 248. The upper housing 234a contains a majority of the remainder of the diaphragm subassembly 206.
As mentioned above, the diaphragm 210 is operatively coupled to the diaphragm rod 212. More specifically, the diaphragm plate 236 couples the diaphragm 210 to the diaphragm rod 212. The diaphragm plate 236 is a contoured circular plate having an outer annual surface 250, an inner annular surface 252, and a central aperture 254. In the embodiment depicted in
The diaphragm 210 includes a relatively flexible disk-shaped member having an outer disk portion 210a arid an inner disk portion 210b. In one embodiment, the diaphragm 210 is constructed of a fabric. However, in alternate embodiments, the diaphragm 210 may be constructed of a polymer or any other material or combination of materials capable of serving, the principles of the present disclosure. The outer disk portion 210a is secured between the diaphragm casing 234b and the upper housing 234a. The inner disk portion 210a is disposed above the diaphragm plate 236 and may be secured to the diaphragm 210 in numerous ways known to one skilled in the art. In an alternative embodiment, the inner disk portion 210a of the diaphragm 210 is not secured to the diaphragm plate 236 at all, but rather, merely gravitationally engages the diaphragm plate 236.
The first and second compression springs 238, 240 are concentrically disposed around the diaphragm rod 212 and between the diaphragm plate 236 and the tipper housing 234a. In the depicted embodiment, the first compression spring 238 has a diameter that is smaller than a diameter of the second compression spring 240. The first compression spring 238 is axially disposed between the lower shelf portion 246 of the upper housing 234a and the inner annular surface 252 of the diaphragm plate 236. The second compression spring 240 is axially disposed between the upper shelf portion 248 of the upper housing 234a and the outer annular surface 250 of the diaphragm plate 236. Accordingly, the first and second compression springs 238, 240 bias the diaphragm plate 236, the diaphragm rod 212, and the diaphragm 210 into the position illustrated in
During operation of the diaphragm subassembly 206, a pressure is introduced into the housing 234 via the inlet port 245. As the pressure increases between the diaphragm 210 and the diaphragm casing 234b, the pressure forces the diaphragm 210 and diaphragm plate 236 downward relative to the orientation of the actuator 200 depicted in
With reference to
More specifically, the lever yoke 217 includes a pair of flanges 264 that extend radially outward from the lever 214. The flanges 264 each include an aperture 266 receiving a bolt 268. The rod end-bearing 243 includes a spherical ball 270 and a threaded shaft 272. The threaded shaft 272 is threaded into the second end 212b of the diaphragm rod 212. The spherical ball 270 includes a cylindrical bore 274 therethrough. The cylindrical bore 274 receives the bolt 268 disposed through the apertures 266 in the flanges 264 of the lever yoke 217. A nut 276 is threaded onto an end of the bolt 268 thereby operatively securing the diaphragm rod 212 to the lever 214.
The lever 214 includes a generally hollow cylindrical member having a central body portion 278, a first end portion 280, a second end portion 282, a first collar portion 284, and a second collar portion 286. The first and second collar portions 284, 286 comprise generally annular collar portions extending radially outward from the central body potion 278. The first collar portion 284 is disposed adjacent the first end portion 280 and includes a first axial end surface 284a. The second collar portion 286 is disposed adjacent the second end portion 282 and includes a second axial end surface 286a. The axial end surfaces 284a, 286a are disposed generally parallel to the inner surfaces 222a, 224a of the cover plates 222, 224, respectively. The first axial end surface 284a faces the inner surface 222a of the first cover plate 222. The second axial end surface 286a faces the inner surface 224a of the second cover plate 224.
With continued reference to
The lever 214 is disposed in the cavity 232 of the housing 202 such that the first end portion 280 is disposed for rotational displacement in the cylindrical bore 222b of the first cover plate 222 and the second end portion 282 is disposed for rotational displacement in the cylindrical bore 224b of the second cover plate 224. In the depicted embodiment of the actuator 200, the cylindrical bores 222b, 224b contain bushings 296 for minimizing any rotational friction between the lever 214 and the cover plates 222, 224.
As illustrated in
Referring specifically to
The collet fingers 251 are located adjacent to the second end portion 282 of the lever 214. The collet fingers 251 are circumferentially spaced and have outer surfaces 251a and inner surfaces 251b. The outer surfaces 251a are shaped and configured to slidably engage the second receiver portion 294 of the lever 214. More specifically, the outer surfaces 251a of the collet fingers 251 are generally shaped as partial frustoconical surfaces. Similar to the second receiver portion 294, the outer surfaces 251a of the collet fingers 251 radially converge from the second end portion 282 of the collet 256 toward the central portion 290 of the bore 288 in the lever 214. The inner surfaces 251b of the collet fingers 251 are shaped and configured to engage the rotary valve shaft 219. For example, as mentioned above, the rotary valve shaft 219 of one embodiment of a rotary valve may have a square cross-section. Accordingly, the inner surfaces 251b of the collet fingers 251 would have flat surfaces such as those depicted in
During assembly, with the cover plates 222, 224 removed from the housing 202, the lever subassembly 208 is attached to the diaphragm subassembly 206 via the lever yoke 217 and rod end-bearing 243, as discussed above. Subsequently, the first and second positioning devices 216, 218 are disposed adjacent the first and second end portions 280, 282 of the lever 214, respectively. In a preferred embodiment, the first and second positioning devices 216, 218 include disk springs, and therefore the first and second positioning devices 216, 218 are disposed onto the first and second end portions 280, 282, respectively, of the lever 214.
Once the positioning devices 216, 218 are located relative to the lever 214, the first and second cover plates 222, 224 are fixed to the body 220 with the plurality of threaded fasteners 226 such that the first end portion 280 of the lever 214 is rotatably supported in the bore 222b of the first cover plate 222 and the second end portion 282 of the lever 214 is rotatably supported in the bore 224b in the second cover plate 224. At this point, the collet 256 would be disposed within the lever 214 such that portions of the collet fingers 251 extend axially outside of the second end portion 282 of the lever 214. So configured, the collet fingers 251 would be spread apart such that a dimension between the inner surfaces 251b thereof would be greater that a cross-sectional dimension of the rotary valve shaft 219. The actuator 200 would then be prepared to be coupled to the valve shaft 219. It should be appreciated by one of ordinary skill in the art that the positioning devices 216, 218 provide a “centering action” on the lever 214, such that during assembly, a predetermined compliance in the lever position results. That is, by providing positional compliance to the lever 214 during tightening, a slight deflection or translation can occur during engagement of the collet 224 and the valve shaft 219. The slight translation, which is proportional to the tolerance between the axial end surfaces 284a, 286a of the lever 214 and the inner surfaces 222a, 224a of the end plates, respectively, substantially prevents the lever 214 from being drawn tight or immediately adjacent to either inner surfaces 222a, 224a, which may substantially reduce the tension imparted to the valve shaft 219 during tightening.
Once the actuator 200 is assembled, the valve shaft 219 is disposed between the collet fingers 251. Next, the draw nut 258 is tightened on the threaded portion 253 of the collet 256. This causes the collet 256 to slidably displace within the bore 288 in the lever 214 toward the left relative to the orientation of the actuator 200 depicted in
As mentioned, the tightening of the draw nut 258 draws the collet 256 through the lever 214. As the collet fingers 251 begin to slidably engage the second receiver portion 294, friction generated therebetween applies a load to the lever 214 which can displace the lever 214 within the housing 202. Particularly, the lever 214 will be displaced in a direction toward the valve shaft or toward the right as depicted in
In response, the second positioning device 218 resiliently deforms. Upon cessation of tightening the draw nut 258, the second positioning device 218 deflects back to its natural state, which is depicted in
In the embodiment depicted herein, the predetermined position comprises a substantially centered position within the housing 202. Under certain conditions, the second positioning device 218 may displace the lever 214 beyond the centered position. Accordingly, as stated above, the actuator 200 disclosed herein is equipped with the first positioning device 216. The first positioning device 216 is generally identical to the second positioning device 218, but located adjacent the first end portion 280 of the lever 214. Therefore, the first positioning device 216 resiliently deflects in a manner just described with respect to the second positioning device 218, but to bias the lever 214 to the right relative to the orientation of the actuator 200 toward the center of the housing 202. Thus, the first and second positioning devices 216, 218 of the disclosed embodiment desirably counteract any axial displacement of the lever 214 to appropriately position the same within the housing 202.
While the actuator 200 has just been described as including a first positioning device 216 and a second positioning device 218 working in cooperation to locate the lever 214, an alternative embodiment may only include one of the first and second positioning devices 216, 218. Furthermore, it should be appreciated that the lever 214 has been described herein as including a first receiver portion 292 and a second receiver portion 294 disposed on opposite ends of the lever 214. However, thus far, the description has only disclosed the second receiver portion 294 serving a specified purpose. It should be appreciated that the actuator 200 disclosed herein is reversible. For example, the orientation of the collet 256 within the lever 214 may be reversed such that the actuator 200 may be adapted to be coupled to a valve shaft of a rotary valve on the left side relative to the orientation of the actuator in
Referring back to
Therefore, as the collet 256 is drawn by tightening of the draw nut 258, the lever 214 displaces along axis 260 and into engagement with the curved spring washer 300 during attachment to a rotary valve, as described above. Thus, the curved spring washer 300 deflects such that the opposing base edges 310 slightly spread apart. This causes the entire curved spring washer 300 to slightly flatten. As the lever 214 is drawn into engagement, the curved spring washer 300 resiliently returns to its original form and forces the lever 214 toward the center of the housing 202.
Similar to that described above with respect to the curved spring 300, as the wave spring 400 undergoes an application of force by the lever 214 during attachment to a rotary valve, the wave spring 400 deflects and slightly flattens out. As the force decreases, the wave spring 4 resiliently returns to its original form and forces the lever 214 toward the center of the housing 202.
Similar to the curved spring washer 300 described above with reference to
Therefore, as the lever 214 engages the finger disk spring 500 during attachment to a rotary valve, as described above, the finger springs 508 and, more particularly the inclined portions 510 of the finger springs 508 detect and the flat portions 512 of the finger springs 508 slide on the inner surfaces 222a, 224a of the respective cover plates 222, 224. Accordingly, the entire finger disk spring 500 slightly flattens. As the force decreases, the finger springs 508 resiliently return to their original form and force the lever 214 toward the center of the housing 202.
It should be understood that in one embodiment of the actuator 200, the load applied to the lever 214 by drawing the collet 256 through the bore 288 is a relatively small load and the deflection of the respective positioning device 216, 218 in response to the load may generally be on the order of between approximately 0.05 inches and 0.15 inches. In a preferred embodiment, for example, the positioning devices 216, 218 such as the curved spring washer 300, the wave spring 400, or the finger disk spring 500 are adapted to deflect on the order of approximately 0.10 inches. However, in alternative embodiments, it should be appreciated that the positioning devices 216, 218 may be adapted to deflect any amount operable to serve the principles of the present disclosure,
As mentioned, the positioning devices 216, 218 described herein generally comprise metal spring devices, for example, the curved spring washer 300, the wave spring 400, or the finger disk spring 500. In one embodiment, however, the positioning devices 216, 218 may comprise any other type of resilient or non-resilient member capable of counteracting the forces generated by drawing the collet 256 through the lever 214. For example, in one alternative embodiment, the positioning devices 216, 218 may comprise rubber springs or grommets, coil springs, lever springs, or any other foreseeable device.
Furthermore, while the positioning devices 216, 218 have been described herein as being positioned adjacent at least one of the first and second end portions 280, 282 of the lever 214, alternative embodiments of the actuator 200 may include the positioning devices 216, 218 disposed within cavities formed in the lever 214 and/or the cover plates 222, 224 of the housing 202. Additionally, although the first positioning device 216 has been disclosed as being generally identical to the second positioning device 218, alternative embodiments of the actuator 200 may include first and second positioning devices 216, 218 that are different from each other. For example, in one alternative embodiment, the first positioning device 216 may include a spring coefficient that is greater than or less than a spring coefficient that the second positioning device 218; or the first and second positioning devices 216, 218 may be constructed of different materials for achieving different objectives. Further yet, while the positioning devices 216, 218 have been disclosed herein as generally axially centering the lever 214 within the cavity 232 of the housing 202, another embodiment of the actuator 200 may comprise one or more positioning devices centering the lever 214 about its axis of rotation 260. For example, in alternative embodiment, one or more positioning device may be disposed between the lever 214 and the bore 222b, 224b of one of the cover plates 222, 224.
Further still, while the positioning devices 216, 218 have been described herein as being incorporated into a rotary valve actuator 200, the positioning devices 216, 218 are not limited to rotary valve actuators and may be implemented in linear drive actuators or any other type of actuator.
Therefore, in light of the foregoing it should be appreciated that the present disclosure provides a rotary valve actuator having a lever that is rotatable within a housing thereof. Specifically, the present disclosure provides an actuator including positioning devices that are operable to bias, force, or otherwise locate the lever in a predetermined position, thereby ensuring an appropriate relationship exists between the actuator and the rotary valve and, particularly, the rotary valve shaft,
