Patent Application
20200217437
The present invention relates to rotary devices such as rotary unions, swivel unions, slip rings and the like.
Fluid coupling devices such as rotary unions or rotary joints are used in various applications such as industrial applications, for example, machining of metals or plastics, work holding, printing, plastic film manufacture, papermaking, and other industrial processes that require a fluid medium to be transferred from a stationary source such as a pump or reservoir into a rotating element such as a machine tool spindle, work-piece clamping system, or rotating drums or cylinder. Additional types of application include use on vehicles, for example to inflate tires during vehicle motion, or to transfer pneumatic or hydraulic fluid into a rotating shaft to activate a propeller pitch adjustment device on a marine application. Often these applications require relatively high media pressures, flow rates, or high machine tool rotational speeds.
One example of a rotary joint can be seen in U.S. Pat. No. 7,407,198 to Ott et al. (“Ott”), which describes a radial rotary transfer assembly. In the device of Ott, a ring-shaped rotor and stationary part include sealing rings therebetween to seal a fluid passage extending through the stationary part and into a shaft disposed within the rotor. While the radial rotary transfer assembly of Ott is at least partially effective in providing a fluid seal between a rotating shaft and a stationary part, its arrangement requires disassembly and/or reassembly, e.g., during service, from one side of the shaft, and further requires cutouts in its sealing rings to prevent their rotation while the rotor is rotating.
The disclosure describes, in one aspect, a rotary joint. The rotary union includes a rotatable assembly adapted for mounting onto a shaft. The rotatable assembly includes an internal fluid opening extending in a radial direction through the rotatable assembly, and two ring seals disposed in opposed orientation on a rotor. Each of the two ring seals is sealably engaged on the rotor and slidable relative to the rotor in an axial direction, which is perpendicular to the radial direction. A non-rotatable assembly is disposed around the rotatable assembly and forms an external fluid opening extending in the radial direction through the non-rotatable assembly. The non-rotatable assembly includes two ring flanges disposed at axially distal ends thereof. Each of the two ring seals slidably contacts a respective one of the two ring flanges to form a mechanical sliding face seal. A radial gap is defined between the rotatable and non-rotatable assemblies. The radial gap is sealed in an axial direction, at least in part, by the mechanical sliding face seals between the two ring seals and the two ring flanges.
In another aspect, the disclosure describes a rotary joint, which includes a rotor adapted for mounting onto a shaft, the rotor including an internal fluid opening extending in a radial direction through the rotor, and two ring seals disposed in opposed orientation on the rotor, each of the two ring seals being sealably engaged on the rotor and slidable relative to the rotor in an axial direction, which is perpendicular to the radial direction. The rotary joint further includes a stator disposed around the rotor and the two ring seals, the stator forming an external fluid opening extending in the radial direction through the stator, the stator including two ring flanges disposed at axially distal ends thereof. Each of the two ring seals slidably contacts a respective one of the two ring flanges to form a mechanical sliding face seal. A radial gap is defined between the rotor and the stator. The radial gap is sealed in an axial direction, at least in part, by the mechanical sliding face seals between the two ring seals and the two ring flanges.
In yet another aspect, the disclosure describes a method for operating a rotary joint. The method includes providing a rotor mounted onto a shaft, the rotor including an internal fluid opening extending in a radial direction through the rotor and fluidly communicating with a fluid passage in the shaft; providing two ring seals disposed in opposed orientation on the rotor, each of the two ring seals being sealably engaged on the rotor and slidable relative to the rotor in an axial direction, which is perpendicular to the radial direction; providing a stator disposed around the rotor and the two ring seals, the stator forming an external fluid opening extending in the radial direction through the stator, the stator including two ring flanges disposed at axially distal ends thereof; slidably contacting a respective one of the two ring flanges with each of the ring seals to form a mechanical sliding face seal; and biasing the two ring flanges away from one another and towards the ring flanges.
In the drawings, which form a part of this specification,
As can be seen from the outline view of
When the rotary joint 100 is installed on a shaft (not shown), the inner sleeve 204 is disposed with a clearance fit around an outer surface of the shaft and overlaps a section thereof that may include fluid openings, for example, for supplying hydraulic fluid to operate a pitch control mechanism of propeller blades (not shown). To seal against leakage of fluid at the inner surface 110, the inner sleeve 204 includes two radial seal grooves 210 disposed axially on either side of the internal fluid openings 106 along the inner surface 110. In the illustrated embodiment, an anti-rotation collar 211, which includes notches 212 that matingly engage with corresponding cutouts or keyways formed in the exterior of the shaft (not shown), rotatably engages the rotor 202 with the rotating shaft (not shown).
The non-rotatable assembly 104 includes a stator 214, which has a generally hollow cylindrical shape and surrounds the rotor 202 in the radial direction. The stator 214 forms the external fluid openings 108, which extend in the radial direction through the stator 214 to fluidly connect the external surface 112 with an internal surface 216 of the stator 214. As can be seen from
To prevent leakage of fluid passing through the radial gap 218, the rotary joint 100 includes two mechanical face seals 222 disposed axially relative to the longitudinal axis L on either side of the radial gap 218. Each face seal 222 has an annular shape and slidingly contacts the two opposed ring flanges 224 and two opposed ring seals 226. In the embodiment shown in
The ring seals 226 are placed in opposing orientation and form part of the rotatable assembly 102. In the embodiment shown in
In the exemplary embodiment shown in
For assembling the rotary joint 100 between a shaft (not shown) and a static receiver (also not shown), the rotor 202 can be installed around a section of the shaft, followed by the ring seals 226 on either side of the rotor 202. The stator 214 can then be placed around the ring seals 226 and the ring flanges 224 installed on either side. For installing the ring flanges, openings 242 may be formed externally thereto to permit engagement with a tool (not shown). Chamfers 244 may be formed on the inner, leading and trailing edges of the rotor 202 to facilitate installation onto a shaft.
As discussed above, the ring seals 226 are rotatably engaged to rotate (or not rotate) with the rotor 202 and form part of the rotatable assembly 102. The rotatable engagement between the ring seals 226 and the rotor 202 can be accomplished in various ways such as keyed arrangements, splines and the like. In the illustrated embodiment, and as shown in
An enlarged cross section of an alternative embodiment of a rotary joint 600 is shown in
In the embodiment shown in
If friction or other external forces and accelerations that may act on the ring seal 226 in its operating environment are disregarded, for sake of discussion, in the presence of a fluid under pressure within the radial gap 218, a hydraulic closing force 606 may act on the ring seal 226 as the seal's closing hydraulic surfaces are exposed to fluid pressure. It is noted that, for the seal on the right of
In the opposite, opening direction, which for the ring seal 226 discussed here is towards the left or away from the ring flange 224, a hydraulic opening force 610 acts on the ring seal 226 as the seal's opening hydraulic surfaces are exposed to fluid pressure. A seal pressure 612, which has a linear profile for incompressible fluids, or a curved profile for compressible fluids, acts along the mechanical face seal 222. If the spring force 608 is not taken into account, the ratio of the opening hydraulic forces over the closing hydraulic forces can define a balance ratio, B, for the ring seal 226, which can be selected to be equal to one (B=1) for a transitional seal, less than one (B<1) for a stable seal, and more than one (B>1) for an unstable seal. In the illustrated embodiment, the balance ratio is less than 85% but other ratios may be used depending on the type of fluid used, the operating pressures, whether an opening, closing or no spring is used, the type of spring and value of spring constant, and other parameters. For example, a larger contact area between sliding surfaces in the mechanical face seal 222 may decrease the balance ratio and, likewise, a smaller contact area can increase the balance ratio.
A cross section of an alternative embodiment for a rotary joint 700 is shown in
More specifically, the threaded connection 228 between the ring flanges 224 and the stator 214, unlike the embodiment shown in
With respect to spring placement, as can be seen in
Finally, for installing the rotor 202 onto the shaft 602, the anti-rotation collar 211 and notches 212 (
When the rotor 202 is installed onto the shaft 602, either singularly or with the remaining components of the rotary joint 700 assembled thereon, the rotor 202 is slid along the shaft 602 until it overlaps the tip 716 of the pin 712. Upon continued motion of the rotor 202, the tip retracts compressing the spring until an axial position in which a ramped notch 718 passes over the tip 716, allowing the tip 716 to extend into the ramped notch 718. The ramped notch 718 has a generally U-shape with slanted axial faces or ramps 720 on either axial end that define a concave depression that faces inwardly. The ramps 720 allow disassembly of the rotor 202 when axially moved along the shaft 602 by causing a compression of the spring 714 and retraction of the tip 716 as the tip 716 follows the ramps 720.
While the tip 716 of the pin 712 is disposed within the notch 718, side faces 722 that are planar and extend parallel to the longitudinal axis L push sideways (into or out from the page in the orientation shown in
In reference to
All references, including publications, patent applications, technical documentation and user manuals, patents, and other material cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.
The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.
Preferred embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.
