The present disclosure relates generally to a contaminate separator, and more particularly, to a contaminate separator for seals of rotating shafts.
Rotating shafts, such as crankshafts or drive shafts, often extend from a housing in which a lubricant, such as oil, is contained. A seal may be provided between the shaft and the housing to prevent leakage and/or contamination of the lubricant. Numerous types of seals (e.g., radial lip seals and end face mechanical seals) have been developed to provide a seal between rotating and stationary machine components. Radial shaft seals, for example, may have two main components including a rigid outer component designed to position and retain the seal in the housing, and a flexible inner lip designed to seal dynamically and statically against the shaft.
Seals utilized in rotating shaft applications may be exposed to contamination by particles naturally present in the ambient air. Such particles may degrade the seal over time, which may lead to high failure rates. For example, contaminates between the seal lip and the shaft may cause excessive heat generation due to the friction generated by the sliding contact. Excessive heat may accelerate aging of the lip material (e.g., a rubber material) and may lead to premature hardening and cracking of the seal lip. In addition, contaminates may abrade, wear, or create grooves in the seal lip and/or shaft, which may degrade the performance and cause leakage.
One attempt to reduce the amount of degradation caused by seal contamination is described in U.S. Pat. No. 4,114,902 (the '902 patent) issued to Orlowski on Sep. 19, 1978. The '902 patent describes sealing rings having a first ring and a second ring. The second ring is permitted to rotate within a recess of the first ring. Various grooves are formed between the rings designed to accumulate particles. The particles are expelled through an orifice in the first ring, where the particles will gravitate to due to the centrifugal action of the first ring rotating.
Although the sealing rings of the '902 patent may be capable of removing some particles that contaminate the seal, they may still suffer from a number of possible drawbacks. For example, the sealing rings of the '902 patent may only be able to remove particles that travel into the grooves of the rings. Therefore, the remaining portions of the seal may still be susceptible to contamination. In addition, the sealing rings of the '902 patent do not prevent particles from entering the seal, but rather, may only remove particles that are already in the seal. Consequently, the sealing rings may still be susceptible to contamination by the particles.
The separators and methods disclosed herein may be directed to mitigating or overcoming one or more of the possible drawbacks set forth above.
In one aspect, the present disclosure is directed to a contaminate separator for a seal of a rotatable shaft. The contaminate separator may include an annular casing defining an internal cavity and being configured to rotate with the rotatable shaft. The annular casing may include an inlet port configured to direct air into the internal cavity. The annular casing may also include a first outlet passage configured to discharge a first air flow from the internal cavity to atmosphere. The annular casing may further include a second outlet passage configured to direct a second air flow from the internal cavity to the seal. The annular casing may be configured to separate particulates from the second air flow.
In another aspect, a seal assembly for a rotatable shaft extending from a housing may include a seal mounted on the rotatable shaft and a contaminate separator mounted adjacent the seal. The contaminate separator may include an annular casing defining an internal cavity configured to rotate with the shaft. The annular casing may include an inlet port configured to direct air into the internal cavity. The annular casing may also include a first outlet passage configured to discharge a first air flow from the internal cavity. The annular casing may further include a second outlet passage configured to direct a second air flow from the internal cavity to the seal. The annular casing may be configured to separate particulates from the second air flow.
In yet another aspect, the present disclosure is directed to a method of protecting a seal mounted on a shaft from airborne contaminates. The method may include rotating a contaminate separator positioned adjacent the seal such that air is drawn into an internal cavity of the contaminate separator. The method may also include separating the air in the internal cavity into a higher-contaminated air flow and a lower-contaminated air flow. The method may further include discharging the higher-contaminated air flow from the internal cavity to the atmosphere. The method may also include directing the lower-contaminated air flow from the internal cavity to the seal
Exemplary seal assembly 10 may include, for example, a seal 16 and a contaminate separator 17 positioned adjacent seal 16. Although exemplary seal 16 is shown in
According to the exemplary embodiment shown in
Inner lip 20 may be coupled to outer component 18 via, for example, bonding or mechanically crimping Inner lip 20 may be configured to contact shaft 12 around its outer circumference and provide both a static and dynamic seal Inner lip 20 may be configured as a retention lip (e.g., as shown in
As shown in
Casing 22 may be formed of one or more components. For example, casing 22 may be formed of two separate annular rings that are configured to be coupled together. For example, according to some embodiments, casing 22 may be formed from two ring-shaped halves that are configured to be coupled around shaft 12. Such an exemplary assembly may simplify installation of separator 17, for example, by eliminating the need to slip separator 17 over the end of shaft 12. The two components may be coupled to each other using a variety of techniques, such as, for example, bonding and/or mechanical fastening.
Axial length 26 and radial thickness 28 of casing 22 may vary depending on, for example, the use and/or the size of the corresponding shaft 12, seal 16, and bore 21. For example, in some embodiments where separator 17 is at least partially recessed within bore 21, radial thickness 28 of at least a portion of casing 22 may be selected to ensure adequate clearance between an outer diameter of separator 17 and an inner surface of bore 21. In some embodiments where a portion of separator 17 is external to bore 21, that external portion may have a greater radial thickness 28 than the portion internal to bore 21, for example, as shown in
According to some embodiments, casing 22 may be configured to be coupled to shaft 12, for example, such that separator 17 may rotate together with shaft 12. Casing 22 may be coupled to shaft 12 by any suitable means, for example, a mechanical interference fit. In some embodiments, for example, where a component of seal 16 rotates with shaft 12 (e.g., for end face mechanical seals), casing 22 may be coupled to the rotating component of seal 16, such that both casing 22 and the rotating seal component rotate with shaft 12. Casing 22 may be coupled to the rotating component of seal 16 by a variety of techniques, such as, for example, adhesive bonding and/or mechanical fastening. In some embodiments, for example, where a component of seal 16 rotates with shaft 12, casing 22 may be formed as an integral component of the seal. For example, the rotating portion of seal 16 may extend out from housing 14 and encompass separator 17.
Casing 22 may be formed from a variety of materials that have suitable material properties. For example, casing 22 may be formed from metal (e.g., aluminum, cast iron, stainless steel, or other alloys), a polymer (e.g., CR, EPDM, PTFE, NBR, or other polymer), a composite (e.g., fiber glass, carbon fiber, reinforced plastics, or other composite), and/or any other materials having similar characteristics. In some embodiments, casing 22 may be formed from a combination of materials, for example, a metal or composite frame encased in a polymer. In some embodiments, casing 22 may be produced by an additive material manufacturing process, for example, 3D printing. The material selection may vary based on the parameters of the application, for example, temperature, rotational speed, pressure, and/or corrosiveness of the environment. A selected material may be sufficiently rigid such that it maintains shape at high rotational speeds.
According to some embodiments, separator 17 may further include one or more inlet ports 30 configured to draw ambient air 31 into the internal cavities 24, for example, as shown in
According to some embodiments, the projection of inlet ports 30 may be oriented toward a direction of rotation 34 of shaft 12 and separator 17. As shaft 12 and separator 17 rotate, ambient air 31 can be induced or directed (i.e., pushed, scooped, or funneled) into the openings of inlet ports 30 and internal cavities 24, for example, as shown in
In some embodiments, inlet ports 30 may be configured such that the orientation of the opening switches based on the direction of rotation of shaft 12. In some embodiments, one or more of inlet ports 30 may be generally flush with the surface of outer axial end wall 32, whereby the rotation of separator 17 draws the ambient air into internal cavities 24. In some embodiments, inlet ports 30 may be positioned on other surfaces of casing 22, for example, an outer annular wall 38.
In the exemplary embodiment shown in
As shown in
As shown in
As shown in
Exemplary separator 17 may further include one or more first outlet passages 52 and one or more second outlet passages 54 defined by casing 22, that are in flow communication with internal cavities 24. Each internal cavity 24 may have a first outlet passage 52 and a second outlet passage 54. In some embodiments, for example, the number of first outlet passages 52 and second outlet passages 54 may correspond to (e.g., may be equal) the number of internal cavities 24. In the exemplary embodiment shown in
In the exemplary embodiment shown in
As shown in
In some embodiments, first outlet passages 52 and second outlet passages 54 may include ramped surfaces forming hood-shaped projections that extend radially outward from the wall on which they are disposed. The hood-shaped projections may have openings that face, for example, away from and/or perpendicular to the direction of rotation 34. For example, in some embodiments, first outlet passages 52 may face away from the direction of rotation 34, while second outlet passages 54 face perpendicular to the direction of rotation toward seal 16. In some embodiments, first outlet passages 52 may be configured to discharge air flows 40 directly to the atmosphere (i.e., ambient environment). For example, as shown in
According to some embodiments, second outlet passages 54 may be configured to direct air flows 44 into bore 21. For example, as shown in
The contaminate separator of the present disclosure may be applicable to any rotary seal where increased reliability and longer life are desired. The disclosed contaminate separator may increase reliability and extend seal life by reducing an amount of contaminates (e.g., particles) in contact with the seal. Operation of contaminate separator 17 will now be discussed in detail.
According to some embodiments, during rotational operation of shaft 12, separator 17 may rotate with shaft 12 and, in some embodiments (e.g., a mechanical face seal), with a rotating component of the seal. While rotating with shaft 12, separator 17 may draw ambient air into internal cavities 24 through inlet ports 30. The ambient air flowing into internal cavities 24 may contain contaminates, for example, particles or particulates of varying size. Due to the rotation of separator 17 and the air inside internal cavities 24, a centrifugal force may be applied to the particles that cause the larger, heavier, and denser particles to move outward, while the smaller, lighter, less dense particles are displaced and move inward. Consequently, the air in internal cavities 24 may be separated into higher-contaminated air flows 40 (e.g., dirtier air flow) and lower-contaminated air flows 44 (e.g., cleaner air flow).
Air flows 40 and air flows 44 may be separated by diverters 46 and discharged from internal cavities 24 by way of first outlet passages 52 and second outlet passages 54, respectively. In some embodiments, first outlet passages 52 may be positioned external to bore 21, thereby enabling air flows 40 to be discharged directly into the atmosphere. In such embodiments, second outlet passages 54 may be positioned within bore 21, thereby enabling air flows 44 to be directed into bore 21. More specifically, air flows 44 may be directed, for example, to inner lip 20 of seal 16.
Air flows 44, being directed into bore 21, may generate a positive pressure (i.e., pressure greater than the surrounding environment) within bore 21. The positive pressure may cause air to flow out of bore 21, thereby inhibiting ingress of ambient air, which may contain larger contaminates (e.g., dust and dirt particles) into bore 21 (e.g., between outer annular wall 38 and the inner surface of bore 21). By inhibiting introduction of ambient air into bore 21, large particles entrained in the ambient air may be inhibited from entering bore 21 and contacting seal 16 at, for example, inner lip 20. The positive pressure difference may range, for example, from greater than about 0 psi to about 3 psi.
Although, the embodiments of contaminate separator 17 disclosed herein have been described in relation to seals that contact a radial surface of the shaft, the use of contaminate separator 17 is not so limited. Contaminate separator 17 may also be used in conjunction with seals configured to contact and seal an axial surface (e.g., an axial end wall) of a rotating shaft.
The disclosed contaminate separator 17 may be manufactured using conventional techniques such as, for example, casting or molding. Alternatively, the disclosed contaminate separator 17 may be manufactured using conventional techniques generally referred to as additive manufacturing or additive fabrication. Known additive manufacturing/fabrication processes include techniques such as, for example, 3D printing. 3D printing is a process wherein material may be deposited in successive layers under the control of a computer. The computer controls additive fabrication equipment to deposit the successive layers according to a three-dimensional model (e.g. a digital file such as an AMF or STL file) that is configured to be converted into a plurality of slices, for example substantially two-dimensional slices, that each define a cross-sectional layer of the contaminate separator 17 in order to manufacture, or fabricate, the contaminate separator. In one case, the disclosed contaminate separator would be an original component and the 3D printing process would be utilized to manufacture the contaminate separator. In other cases, the 3D process could be used to replicate an existing contaminate separator and the replicated contaminate separators could be sold as aftermarket parts. These replicated aftermarket contaminate separators could be either exact copies of the original contaminate separators or pseudo copies differing in only non-critical aspects.
With reference to
The three-dimensional model may be formed in a number of known ways. In general, the three-dimensional model is created by inputting data 1003 representing the contaminate separator to a computer or a processor 1004 such as a cloud-based software operating system. The data may then be used as a three-dimensional model representing the physical contaminate separator. The three-dimensional model is intended to be suitable for the purposes of manufacturing the contaminate separator. In an exemplary embodiment, the three-dimensional model is suitable for the purpose of manufacturing the contaminate separator by an additive manufacturing technique.
In one embodiment depicted in
The additive manufacturing process utilized to create the disclosed contaminate separator 17 may involve materials such as plastic, rubber, metal, etc. In some embodiments, additional processes may be performed to create a finished product. Such additional processes may include, for example, one or more of cleaning, hardening, heat treatment, material removal, and polishing. Other processes necessary to complete a finished product may be performed in addition to or in lieu of these identified processes.
It will be apparent to those skilled in the art that various modifications and variations can be made to the contaminate separator of the present disclosure without departing from the scope of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed contaminate separator. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
This application is entitled to and claims the benefit of priority from U.S. application Ser. No. 14/705,092 (Attorney Docket no. 08350.1873) by Davis, Tyler J., filed May 6, 2015, the contents of which are expressly incorporated herein by reference.
Number | Date | Country | |
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61996999 | May 2015 | US |