Patent Description:
Conventional rotary seals are employed in a wide variety of environments and settings, such as for example, in mechanical apparatuses, to provide a fluid-tight seal. The sealing assemblies are usually positioned about a rotating shaft or rod that is mounted in and protrudes from a stationary mechanical housing. Polymer or rubber seals are generally not present in split configurations.

A seal may be deployed upon equipment. As the equipment ages, several problems may develop. For example, as a rotating shaft ages, the radially outer surface of the shaft (i.e., the surface of the shaft presented to the sealing surface of the seal) may become inconsistent, pitted, pocked, damaged, or otherwise made uneven. If the sealing surface of a seal assembly cannot conform to the uneven surface of the shaft, the seal assembly will not be capable of maintaining a tight seal with the shaft.

Furthermore, the shaft may not be rotating perfectly concentrically within the equipment. For example, the centerline of the equipment bore and the shaft may not be coincident during operation. The concentricity of the shaft is indicated by the Total Indicated Runout (TIR) of the shaft. In real-world applications, the TIR of a shaft is typically not zero; that is, the shaft will move radially towards and away from the seal as the shaft rotates. If the seal is unable to move radially with the shaft, the sealing performance of the seal assembly is degraded. As a result, many conventional seals do not perform adequately and wear out prematurely.

<CIT> discloses a seal assembly for high pressure dynamic and static services. <CIT> discloses a seal arrangement for a piston rod, according to the preamble of claim <NUM>.

The present application addresses these and other problems, as described in more detail below.

The present invention is generally directed to a split rotary seal assembly employing an energizer, housing, and a rotational seal element such as a matrix. The seal assembly seals against a rotating shaft to prevent the leakage of petroleum and synthetic oil, grease, and other fluids.

In the presently described sealing assembly, the matrix and energizer may move and deform. Due to combined movement of energizer and matrix, the matrix follows shaft in radial displacements. Thus, the matrix moves radially in/out within the housing to follow the shaft, even though the shaft may not be rotating concentrically within the equipment. As the sealing element follows the shaft runout, the surfaces of the matrix that are perpendicular to the shaft maintain a leakfree interface with the inside channel walls of the housing.

Furthermore, due to the nature of the presently described matrix, the matrix will comply with inconsistent or damaged surfaces within older equipment, but will not wear excessively due to abrasion resistance. Accordingly, the matrix provides an effective seal on worn or degraded shaft surfaces, while still maintaining sealing capability on new surfaces.

According to one embodiment an annular mechanical seal assembly, and a method of fabricating a mechanical seal assembly, are provided.

The annular mechanical seal assembly includes a housing having a radially interior inside channel defined at least in part by an interior axially extending wall. The housing may be formed from elastomer, plastic, polyeurethane, or metal. The radially interior inside channel includes an interior axially extending wall and two interior substantially radially extending walls.

The housing may further include a radially inner first slanted wall extending from one of the interior substantially radially extending walls to a meeting point, and a radially inner second slanted wall extends from the meeting point to a radially extending exterior wall of the housing, the radially inner first slanted wall and the radially inner second slanted wall being slanted away from the axial direction at different angles. The first and second slanted walls may serve to prevent a sealing element (such as a matrix) disposed in the radially interior inside channel from rotating.

The housing may also include one or more static sealing elements provided on a radially outer surface of the housing. The one or more static sealing elements may be integral with the housing, or may be provided in a radially exterior outside channel of the housing. The static sealing element may be an O-ring.

The annular mechanical assembly further includes a matrix provided substantially within the radially interior inside channel of the housing and protruding from the radially interior inside channel. The matrix has a radially inner surface for sealing against the shaft. The matrix may include composite reinforced fibers or yarns and one or more lubricants. The fibers or yarns may be carbon, aramid, rayon, kynol, Kevlar, cotton, and polytetrafluoroethylene (PTFE) fibers or yarns. The fibers may be woven or braided. The lubricants may include carbon, graphite, and PTFE based lubricants.

The matrix may have an inner diameter and the housing has an inner diameter defined at the radially innermost point of the housing, and the inner diameter of the matrix is less than the inner diameter of the housing. In this way, a portion of the matrix may extend beyond the housing, thereby preventing the housing from coming into contact with the rotating shaft. The annular mechanical assembly comprises an anti-rotational mechanism to prevent the matrix from rotating with the shaft.

The annular mechanical assembly further includes an energizer for providing a radial force to the matrix. The energizer may be made up of elastomer, foam, silicone, fluorocarbons, ethylene propylene diene Monomer (M-class) rubber (EPDM), nytrile, a sponge, or a metallic spring.

The energizer is disposed in the radially interior inside channel of the housing between the matrix and the interior axially extending wall in the radial direction. The energizer presses against the interior walls of the radially interior inside channel when compressed.

The energizer may be selected to be less rigid than the matrix, and furthermore may be selected to have a resistive force of <NUM>-<NUM> N/mm.

One or more of the housing, the matrix and the energizer may have two ends and comprise a split separating the two ends. Further, at least one of the energizer and the matrix is in the form of a cord. By forming the energizer or matrix in the form of a cord, the energizer or matrix can be easily split. Providing a split may serve to ease installation.

Other exemplary embodiments provide a pressure actuation passage for introducing a process fluid at a higher than ambient pressure for energizing the matrix. The pressure actuation passage may be provided in a radially extending side of the housing and may extend into the radially interior inside channel at a location lateral to the energizer. The pressure actuation passage allows for additional sealing force to be applied to the matrix, further enhancing the assembly's sealing properties.

The anti-rotational mechanism comprises an anti-rotational element for preventing the matrix from rotating, the anti-rotational element extending through the housing and energizer and into the matrix. The anti-rotational element may be a pin or a screw inserted through the housing in a radial direction. In some embodiments, the anti-rotational element may be inserted into a thru-hole in the housing, and the thru-hole may permit radial movement of the anti-rotational element. The amount of radial movement permitted may be controlled by a sleeve.

In another configuration, a unitized housing made from an elastomer material (i.e. polyurethane) is provided. Thinner sections of the body allow flexure for radial movement and simultaneously provide anti-rotation for the matrix.

In yet further embodiments, a fluid leakage collecting channel may be provided for collecting fluid from the shaft.

These and other features and advantages of the present invention will be more fully understood by reference to the following detailed description in conjunction with the attached drawings in which like reference numerals refer to like elements through the different views. The drawings illustrate principals of the invention and, although not to scale, show relative dimensions.

The present invention provides a mechanical seal assembly for providing sealing on a rotating shaft. The invention will be described below relative to illustrated embodiments. Those skilled in the art will appreciate that the present invention may be implemented in a number of different applications and embodiments and is not specifically limited in its application to the particular embodiment depicted herein.

In some embodiments, a split rotary seal assembly employing an energizer, housing, and a rotational seal element such as a matrix is provided. The seal assembly seals against a rotating shaft to prevent the leakage of petroleum and synthetic oil, grease, and other fluids.

Exemplary embodiments of a matrix split rotary seal assembly according to the present invention are useful for sealing against surfaces rotating at a low to a high speed and at a variety of pressure conditions, from vacuum to a high pressure differential across the seal. Exemplary embodiments are suitable for high shaft runout applications, because the matrix follows the shaft in radial displacements. Further, because the matrix conforms to the surface of the rotating shaft, the presently described matrix split rotary seal is effective on worn or degraded shaft surfaces. Ease of installation is facilitated due to a split formed in the housing, energizer, and matrix, although the assembly may be solid in some embodiments.

In some embodiments, a pressure actuating feature is provided in the housing. Accordingly, additional pressure may be provided to the matrix and the energizer to further enhance the sealing capabilities of the seal assembly. An anti-rotational mechanism is provided to prevent the matrix from rotating with the shaft.

Exemplary embodiments of the present invention are particularly useful for large diameter rotating shafts (e.g., <NUM> - <NUM>) with a long lifespan or high speed or wear characteristics, such as those found on wind turbines. However, the present invention is not so limited, and may be equally employed on smaller shafts or other surfaces. Further, although exemplary embodiments are described as sealing against a rotating shaft, one of ordinary skill in the art will recognize that the present invention is not so limited, and may be employed with any suitable sealing surface.

Exemplary embodiments of the present invention will be described with reference to the following terms.

The terms "seal assembly" and "sealing assembly" as used herein are intended to include various types of sealing assemblies, including single seals, split seals, concentric seals, spiral seals, and other known seal and sealing assembly types and configurations.

The term "shaft" is intended to refer to any suitable device in a mechanical system to which a seal can be mounted and includes shafts, rods and other known devices.

The terms "axial" and "axially" used herein refer to a direction generally parallel to the axis of a shaft. The terms "radial" and "radially" used herein refer to a direction generally perpendicular to the axis of a shaft, in a direction away from the center of the shaft. The terms "fluid" and "fluids" refer to liquids, gases, and combinations thereof.

The term "radially inner" as used herein refers to the portion of the seal assembly proximate a shaft. Conversely, the term "radially outer" as used herein refers to the portion of the seal assembly distal from a shaft.

The terms "stationary equipment", "static surface" and " gland" as used herein are intended to include any suitable stationary structure housing a shaft or rod to which a seal is secured.

The phrase "ambient environment" or "ambient pressure" is intended to include any external environment or pressure other than the internal environment of the housing of the seal assembly.

The present invention will be better understood with reference to the attached Figures.

<FIG> is a close-up cross-sectional perspective view of a matrix split rotary seal assembly <NUM> according to an illustrative example of the invention. As shown in <FIG>, a matrix <NUM> or other rotational sealing element is provided on the radially interior side of the matrix split rotary seal assembly <NUM>. The matrix <NUM> forms a dynamic sealing element made up of a composite reinforced fiber impregnated with one or more lubricants. The matrix may be formed directly into the radially interior inside channel <NUM> of the housing <NUM>.

The matrix <NUM> is not generally a stiff solid material. It may be a material with a large percentage (by weight and volume) of fibers and yarn combined with lubricants or polymer based dispersions. The composite reinforced fiber of the matrix <NUM> may be a natural or synthetic fiber. Suitable fibers include, but are not limited to, one or a combination of carbon, aramid, rayon, kynol, Kevlar, cotton, and polytetrafluoroethylene (PTFE) fibers or yarns. The inventors have generally found that the robust nature of fiber reinforcement is superior as compared with sintered PTFE and rubber compounds. The fibers may be woven or braided in a textile fashion. The lubricants of the matrix <NUM> may include carbon, graphite, PTFE, or other lubricants.

Accordingly, the matrix <NUM> provides the enhanced benefits of low friction materials with the high strength of a composite with high tensile strength fiber reinforcement. This combination provides for high pressure-velocity (PV) running characteristics operating on a rotating shaft. Due to the matrix's <NUM> flexibility resistance, the matrix <NUM> will comply with inconsistent or damaged surfaces within older equipment, but will not wear excessively due to abrasion resistance.

The matrix <NUM> can meld to conform to both small and relatively large imperfections in the counter-sealing surface of a rotating shaft, as might be found on an old or worn shaft. This alleviates the need to repair, replace, or reconstruct equipment, while still providing sealing properties against new surfaces.

The matrix <NUM> may be in cord form. By providing the matrix <NUM> in cord form, the matrix <NUM> may easily be provided in a split configuration, making the matrix <NUM> conducive for use with small to very large diameter equipment. If the matrix <NUM> is split with a skieve cut, the matrix <NUM> can be easily re-assembled.

The matrix <NUM> may be formed in different cross-sectional geometries. Suitable geometries may include a square, rectangle, trapezoid, and other sealing element geometries that will be familiar to one of ordinary skill in the art.

An energizer <NUM> is provided between the matrix <NUM> and a portion of the housing <NUM>, and provides a seal force to the matrix <NUM> which is directed in a radially inward direction. The energizer may be made from elastomer, closed foam elastomer, other foams, silicone, fluorocarbons, ethylene propylene diene Monomer (M-class) rubber (EPDM), nytrile, a sponge, or a metallic spring. For example, the energizer may be made from a 50A durometer material.

The energizer material and shape is selected to have appropriate stress/strain characteristics. In general, the energizer has a spring constant which dictates how much sealing force is applied to the matrix. The energizer optimally applies a spring load of <NUM> N/mm, although spring loads in the range of <NUM>-<NUM> N/mm are also suitable for exemplary embodiments of the present invention.

The energizer should generally be selected to be less rigid than the matrix so that the energizer deforms before the matrix. At the same stress level, the strain on the energizer should typically be an order of magnitude or more higher than the matrix.

The energizer <NUM> may be provided in cord form so that the energizer <NUM> may be easily placed within the radially interior inside channel <NUM> of the housing <NUM>, and so that the energizer <NUM> may be easily split. The energizer may have a generally cylindrical shape that is circular in cross-section, although other geometric shapes are also suitable for embodiments of the present invention.

The seal force applied to the matrix <NUM> by the energizer <NUM> can be varied by using energizer materials of different hardness and foams with different densities. The range of deflection within these materials will also dictate the load force applied.

The matrix <NUM> and energizer <NUM> are supported in a housing <NUM>. The housing <NUM> is an integrated component that fits directly into equipment. The housing <NUM> is an annular body with an inside diameter channel. The housing130 may be formed from elastomer, plastic, polyeurethane, or metal. The housing <NUM> should generally be rigid enough to act as a housing for the other components of the seal assembly, but should be flexible enough to be split and wrapped around a rotating shaft.

The housing <NUM> may generally have an "H" shape in cross-section. The cross-sectional shape of the housing <NUM> may be formed by providing a radially exterior outside channel <NUM>, and a radially interior inside channel <NUM>. The radially interior inside channel <NUM> accommodates the matrix <NUM> and the energizer <NUM>, while the radially exterior outside channel <NUM> may accommodate one or more static sealing surfaces. The radially exterior outside channel <NUM> is not necessarily provided in all illustrative examples.

Static sealing surfaces are provided on the outside diameter of the housing <NUM>. The static sealing surfaces may be integral with, or formed as a part of, the housing <NUM>, as in the case of the housing integral static sealing surfaces <NUM>.

Alternatively, a separate static sealing element <NUM>, such as an O-ring, gasket, or other sealing element may be provided and may be supported in the radially exterior outside channel <NUM> of the housing, or by grooves in the housing.

The integral static sealing surfaces <NUM> may also be employed in combination with one or more separate static sealing elements <NUM>. Whether to provide integral or non-integral static sealing elements is dependent upon the particular application for the sealing assembly <NUM>. For example, if anti-rotational screws or pins are provided (see <FIG> and <NUM>, described below), a non-integral static sealing element may be used to cover the proximal end of the anti-rotational element. On the other hand, integrally-formed static sealing elements may be less expensive to produce and simpler to deploy than non-integral static sealing elements.

The matrix <NUM> and energizer <NUM> are provided in a radially interior inside channel <NUM> of the housing <NUM>. The matrix <NUM> is provided at the most radially interior location of the assembly <NUM> and faces a rotating shaft to provide sealing against the shaft. The energizer <NUM> is situated between the matrix <NUM> and an axially extending wall of the radially interior inside channel <NUM> in the radial direction.

The manner in which these sealing elements fit together to form an annular assembly is shown in <FIG> is a cutaway perspective view depicting an exemplary matrix split rotary seal assembly <NUM> having a matrix <NUM>, an energizer <NUM>, and a housing <NUM>.

As shown in <FIG>, a radially inner matrix surface <NUM> is provided at a radiallyinnermost portion of the seal assembly. The radially inner matrix surface <NUM> faces towards the radial center of the seal assembly and contacts a rotating shaft (or other piece of equipment) to provide a sealing surface of the assembly <NUM>. The radially inner matrix surface <NUM> is typically a flat surface, although the shape of the radially inner matrix surface <NUM> will vary depending on the shape of the matrix <NUM>.

A radially outer matrix surface <NUM> is provided on the opposite end of the matrix <NUM> from the radially inner matrix surface <NUM>. The radially outer matrix surface <NUM> faces the energizer <NUM>. During operation, the energizer <NUM> may be compressed so that at least a portion of the energizer <NUM> presses against the radially outer matrix surface <NUM>. Accordingly, the matrix is energized and a radially directed sealing force may be applied.

The housing <NUM> includes a radially outer housing surface <NUM>. The radially outer housing surface <NUM> faces a static surface and accommodates one or more static sealing elements. Thus, the radially outer housing surface <NUM> may establish a seal against the static sealing surface.

The housing <NUM> additionally has a radially inner housing surface <NUM>. The radially inner housing surface <NUM> may be provided with one or more slanted surfaces in order to secure the matrix <NUM> during operation, so that the matrix <NUM> does not rotate with a rotating shaft. The slanted surfaces are described in more detail with respect to <FIG>.

The radially inner matrix surface <NUM> protrudes from the radially inner housing surface <NUM> towards the radial center of the assembly <NUM>. As will be discussed in more detail below with respect to <FIG>, by allowing the matrix <NUM> to extend beyond the end of the housing <NUM>, the ends of the matrix <NUM> will be compressed between the housing <NUM> and a rotating shaft around which the seal assembly <NUM> is disposed. This prevents the housing <NUM> from making contact with the rotating shaft in operation.

Whilst not specifically showing an anti-rotational mechanism, <FIG> is a perspective view of an assembled matrix split rotary seal assembly <NUM> according to an illustrative embodiment of the invention. The matrix <NUM> is split at a matrix split <NUM>. This facilitates ease of installation of the matrix <NUM> about a rotating shaft. Furthermore, as noted above the matrix extends radially beyond the radially inner end <NUM> of the housing, exposing a matrix side portion <NUM>. During operation, this side portion <NUM> is compressed and disposed between the housing radially inner surface <NUM> and a rotating shaft.

The housing is split at a housing split <NUM>. The housing split <NUM> is provided to facilitate ease of installation. In some embodiments, the housing split <NUM> provides other advantages, such as preventing misalignment and allowing system pressure to enhance sealing at the interface of the split <NUM>. Housing splits are described in more detail with reference to <FIG>, below.

Although hidden in <FIG>, the energizer is also split. In operation, due to the mechanical compression of the energizer within an annular region between the inside diameter of the annular housing and the outside diameter of the matrix the split ends of the energizer are squeezed together and forced against each other. Thus, the split ends of the energizer form a leak proof joint.

The housing includes two radially extending surfaces disposed on opposite sides in the axial direction. A housing first radially extending surface <NUM> is shown in <FIG>, while a housing second radially extending surface <NUM> is provided on the opposite side of the assembly <NUM> and is hidden from view.

Whilst not specifically showing an anti-rotational mechanism, a fully assembled matrix split rotary seal <NUM> is depicted in <FIG>. The assembly <NUM> may include straps <NUM> for temporarily securing the matrix <NUM> to the housing <NUM>. The housing <NUM> is split at a housing split <NUM>. More or fewer housing splits <NUM> may also be provided.

In operation, the assembly <NUM> would be deployed between a rotating shaft and a static surface. For example, <FIG> is a cross-sectional view depicting a shaft <NUM>, an exemplary matrix split rotary seal assembly according to an illustrative example, and a static component <NUM>.

As indicated in <FIG>, the axial direction generally follows the longitudinal length of the shaft. The radial direction extends outwardly from the center of the shaft in a direction perpendicular to the axial direction. It should be noted that the radial direction indicated in <FIG> is only one example of a radial direction.

A rotating shaft <NUM> is provided at the radial center of the seal assembly. The seal assembly forms a seal between the radially outer surface of the rotating shaft <NUM> and the radially inner surface of the matrix <NUM>. The energizer <NUM> is disposed between the matrix <NUM> and an axially extending inner wall of a housing <NUM>.

The static component <NUM> includes a radially inner surface, against which a radially outer surface of the housing <NUM> effects a seal. This may be accomplished by providing a static sealing surface <NUM> which is integral with the radially outer surface of the housing, or by providing one or more elastomeric static sealing elements <NUM> in a radially exterior outside channel of the housing <NUM>. Examples of suitable elastomeric static sealing elements <NUM> include o-rings, gaskets, and other elastomeric structures suitable for effecting a seal.

Instead of providing separate, non-integral , static sealing elements <NUM>, the static sealing can be effected solely using an integral sealing surface <NUM> on the radially outer end of the housing <NUM>, as in the illustrative example depicted in <FIG>.

<FIG> is a cross-sectional perspective view of a matrix split rotary seal according to another illustrative example. A rotating shaft <NUM> effects a seal with a radially inner surface of a matrix <NUM>. The matrix <NUM> is energized by an energizer <NUM>, and the matrix <NUM> and energizer <NUM> are provided in a housing <NUM>. Integrated housing static sealing surfaces <NUM> effect a seal with a static component <NUM>.

As further shown in <FIG>, the matrix <NUM> has a matrix inner diameter DiM <NUM>, which is measured from the radially inner surface of the matrix <NUM>. The matrix inner diameter DiM <NUM> is determined by the diameter of the shaft <NUM> against which the matrix <NUM> will effect a seal.

Further, the housing <NUM> defines a housing first inner diameter DiH1 <NUM>, which is measured from the radially innermost point on radially innermost surface the housing. A housing second inner diameter DiH2 <NUM> is measured from the radially outermost point on the radially innermost surface of the housing. In a preferred embodiment, the matrix inner diameter DiM <NUM> is less than the housing first inner diameter DiH1 <NUM>. In this way, a portion of the matrix <NUM> protrudes outside the housing <NUM> in the radial direction.

The housing further defines a housing outer diameter DoH <NUM>, which is measured across the radially outermost points on the housing. This is typically the point at which the housing static sealing surface <NUM> contacts the static surface <NUM>.

The seal assembly <NUM> of <FIG> is shown in more detail in the cross sectional views of <FIG>.

<FIG> is a cross-sectional view of the matrix split rotary seal assembly of <FIG>. As shown in <FIG>, a rotating shaft <NUM> effects a seal with a radially inner surface of a matrix <NUM>. The matrix <NUM> is energized by an energizer <NUM>, and the matrix <NUM> and energizer <NUM> are provided in a housing <NUM>. The radially outer surface of the housing <NUM> effects a seal with a static component <NUM>.

<FIG> is a cross-sectional view of the matrix split rotary seal assembly of <FIG> showing the matrix <NUM> and the energizer <NUM> in more detail.

The matrix <NUM> is defined by a matrix width <NUM> and a matrix height <NUM>. The matrix width <NUM> and height <NUM> will vary depending on the size and application of the seal assembly. In one exemplary embodiment the matrix width <NUM> is <NUM> and the matrix height <NUM> is <NUM>.

Furthermore, the dimensions of the matrix <NUM> will vary depending on the cross-sectional geometry of the matrix <NUM>. The matrix <NUM> need not be rectangular in cross-section, but may accommodate any of a variety of suitable shapes, such as a trapezoid.

The energizer diameter <NUM> defines the cross-sectional size of the energizer. The energizer <NUM> need not be circular in cross-section, but may accommodate any of a variety of suitable shapes, such as a rectangle or trapezoid.

Typically, the energizer diameter <NUM> and the matrix width <NUM> may be dictated by the size and shape of the radially interior inside channel of the housing <NUM> in which the matrix <NUM> and the energizer <NUM> are disposed. The energizer diameter <NUM> and the matrix width <NUM> are slightly larger than the width of the radially interior inside channel to ensure a snug fit and ease operation.

Furthermore, the energizer diameter <NUM> and the matrix height <NUM> in combination may be dictated by the radial length of the radially interior inside channel of the housing <NUM>. The energizer diameter <NUM> and the matrix height <NUM> should be selected so that the matrix <NUM> may protrude from the radially interior side of the housing <NUM>, even when the matrix <NUM> and the energizer <NUM> are compressed during operation.

As shown in <FIG>, a cross section of the housing <NUM> may be symmetrical about a centerline draw in the radial direction. The housing <NUM> has an overall housing depth <NUM>, extending from one radially extending face of the housing <NUM> (e.g., radially extending face <NUM>) to radially extending face on the opposite side of the housing <NUM> in the axial direction. Although the housing depth <NUM> will vary by application, an exemplary housing depth <NUM> is <NUM>.

The housing <NUM> is also defined by the housing outermost width <NUM>, which extends in the radial direction from the radially innermost point on the housing to the radially outermost point of the housing. Although the housing outermost width <NUM> will vary by application, an exemplary housing outermost width <NUM> is <NUM>.

As shown in <FIG>, the housing <NUM> includes two arms <NUM>, <NUM> surrounding the radially interior inside channel <NUM>. Each of the arms <NUM>, <NUM> has an inner depth <NUM>. Although the inner depth <NUM> will vary by application, an exemplary inner depth <NUM> is <NUM>.

The arms <NUM>, <NUM> surround the radially interior inside channel <NUM>, which includes three walls. An interior axially extending wall <NUM> is provided at the radially outermost location of the radially interior inside channel <NUM> and extends between the two arms <NUM>, <NUM>. Although the length of the interior axially extending wall <NUM> will vary by application, an exemplary length is <NUM>.

The radially interior inside channel <NUM> further includes two interior substantially radially extending walls <NUM>, <NUM>. The substantially radially extending walls <NUM>, <NUM> extend substantially in the radial direction. However, the substantially radially extending walls <NUM>, <NUM> may extend at an angle from the radial direction, such as an angle in the range of <NUM> to <NUM> degrees. Thus, the substantially radially extending walls <NUM>, <NUM> may cause the radially interior inside channel <NUM> to taper towards a radially interior end, thus securing and slightly compressing the matrix <NUM>. Although the length of the substantially radially extending walls <NUM>, <NUM> will vary by application, an exemplary length is <NUM>.

<FIG> is a close up of a radially outer portion of the cross-sectional view of the matrix split rotary seal assembly of <FIG>. As shown in <FIG>, the housing <NUM> includes a series of raises surfaces for effecting a seal against a static surface <NUM>. Each raised surface extends radially outwardly from a flat axially extending surface of the housing <NUM> by a predetermined distance <NUM>. Although the amount of the predetermined distance <NUM> will vary by application, an exemplary amount is <NUM>.

Further, more than one raised surface may be provided, depending on the application. In the exemplary sealing assembly depicted in <FIG>, three such surfaces are present. Each raised surface includes a peak at a point where the raised surface makes contact with the static surface <NUM> and a trough at a point where the raised surface returns to the height of the flat axially extending surface of the housing <NUM>. Accordingly, a housing integrated static sealing element peak-to-peak distance <NUM> is defined between the peaks of two adjacent raised surfaces. The amount of the peak-to-peak distance <NUM> will vary by application. Similarly, a housing integrated static sealing element trough-to-trough distance <NUM> is also defined. Although the amount of the trough-to-trough distance <NUM> will vary by application, an exemplary amount is <NUM>.

Furthermore, the axially outermost raised surfaces may reach a trough a certain distance from the axially outer edges of the housing <NUM>. Accordingly, a housing integrated static sealing element trough-to-edge distance <NUM> is defined. Although the amount of the trough-to-edge distance <NUM> will vary by application, an exemplary amount is <NUM>. The trough-to edge distance <NUM> may be zero; that is, the axially outermost raised surfaces may end directly on the axially outer edges of the housing <NUM>.

Further, the raised surfaces which extend from the flat axially extending surface of the housing <NUM> are provided at a predefined distance <NUM> away from the previously described housing interior axially extending wall <NUM>. The amount of the predefined distance <NUM> will vary by application.

<FIG> is a close up of a radially inner portion of the cross-sectional view of the matrix split rotary seal assembly of <FIG>. As previously described, a portion <NUM> of the matrix is exposed beyond the end of the housing <NUM>. Although the amount of the exposed portion <NUM> may vary depending on the application, an exemplary amount is <NUM>.

Furthermore, a housing radially inner first slanted wall <NUM> and a housing radially inner second slanted wall <NUM> extend along the radially innermost surface of the housing <NUM> and meet at a meeting point <NUM>. The housing radially inner first slanted wall <NUM> and the housing radially inner second slanted wall help to prevent the matrix <NUM> from rotating. The angles of the housing radially inner first slanted wall <NUM> and the housing radially inner second slanted wall <NUM> (relative to the axial direction) may be selected accordingly. Generally, the angle of the housing radially inner first slanted wall <NUM> is different than the angle of the housing radially inner second slanted wall <NUM>. The angle of the housing radially inner first slanted wall <NUM> may be selected from a range encompassing <NUM>°-<NUM>° relative to the axial direction. The angle of the housing radially inner second slanted wall <NUM> may be selected from a range encompassing <NUM>°-<NUM>° relative to the axial direction.

The various components of the sealing assembly may be compressed during operation. <FIG> depicts a matrix split rotary seal assembly according to the first embodiment of the invention in operation, showing a change in shape of the energizer and matrix.

A rotating shaft <NUM> effects a seal with a radially inner surface of a matrix <NUM>. The matrix <NUM> is energized by an energizer <NUM>, and the matrix <NUM> and energizer <NUM> are provided in a housing <NUM>. Integrated housing static sealing surfaces <NUM> effect a seal with a static component <NUM>.

In operation, the energizer <NUM> compresses and conforms to the boundaries of the radially interior inside channel <NUM> of the housing <NUM>. As the energizer <NUM> compresses, the energizer may form four sides. By conforming to the boundaries of the radially interior inside channel <NUM> of the housing <NUM>, the energizer <NUM> provides sealing areas on each of the three facing sides of the radially interior inside channel <NUM> of the housing <NUM> and the outside diameter of the matrix <NUM>. The energizer <NUM> may also act as a static seal between the matrix <NUM> and an axially extending inner wall of the radially interior inside channel <NUM> of the housing <NUM>.

The matrix <NUM> moves radially in/out within the housing <NUM> to follow the shaft <NUM> which may not be rotating concentrically within the equipment. Due to the combined movement of energizer <NUM> and matrix <NUM>, the matrix <NUM> follows the rotating shaft <NUM> in radial displacements.

As the matrix <NUM> follows the shaft <NUM> runout, the surfaces of the matrix <NUM> that are perpendicular to the shaft <NUM> maintain a leakfree interface with the radially interior inside channel <NUM> walls of the housing <NUM>. Furthermore, the seal assembly does not need to be constantly readjusted.

A third example not part of the invention is depicted in <FIG>. As shown in <FIG>, a rotating shaft <NUM> effects a seal with a radially inner surface of a matrix <NUM>. The matrix <NUM> is energized by an energizer <NUM>, and the matrix <NUM> and energizer <NUM> are provided in a housing <NUM>. Two static sealing elements <NUM> effect a seal with a static component <NUM>.

As shown in <FIG>, in operation the matrix <NUM> may deform by a certain deformation amount <NUM>. The deformation amount <NUM> may vary depending on the application. Furthermore, in operation the energizer <NUM> may deform by a second deformation amount <NUM>. Although the second deformation amount <NUM> may vary depending on the application, an exemplary amount is <NUM>.

<FIG> is a close up of a radially outer portion of the matrix split rotary seal of <FIG>. As shown in <FIG>, the static sealing elements <NUM> (o-rings in the present case) have a static sealing element diameter <NUM>. Although the static sealing element diameter <NUM> may vary depending on the application, an exemplary amount is <NUM>.

A portion <NUM> of the static sealing element <NUM> is exposed above an axially extending surface of the housing <NUM>. The size of the exposed portion <NUM> may generally correspond to the static sealing element height <NUM> of <FIG>, and may be selected by varying the depth of the radially exterior outside channels <NUM> provided on a radially exterior axially extending surface of the housing <NUM>. The radially exterior outside channels <NUM> are each defined by radially extending walls <NUM> and an axially extending wall <NUM>. The first radially extending wall <NUM> extends from a first radially exterior axially extending wall <NUM> in a radial direction and terminates at a second radially exterior axially extending wall <NUM>. A second radially extending wall extends from the first radially exterior axially extending wall <NUM> in a radial direction and terminates at a third radially exterior axially extending wall <NUM>.

In this way, one or more radially exterior outside channels <NUM> may be provided for accommodating static non-integral sealing elements <NUM>.

A fourth example not part of the invention employing a pressure actuation port is described with reference to <FIG>. As shown in <FIG>, a rotating shaft <NUM> effects a seal with a radially inner surface of a matrix <NUM>. The matrix <NUM> is energized by an energizer <NUM>, and the matrix <NUM> and energizer <NUM> are provided in a housing <NUM>. Two static sealing surfaces <NUM> formed on a radially outward side of the housing <NUM> effect a seal with a static component <NUM>, in conjunction with a non-integral static sealing element <NUM>.

Further, the housing <NUM> includes one or more pressure actuating ports <NUM>. The pressure actuating port <NUM> is drilled axially into the housing at a location radially lateral to the energizer <NUM>. Process fluid at a pressure higher than the ambient pressure may be supplied through the pressure actuating port <NUM>. This allows process pressure to actuate the energizer, thereby applying additional force on the outside diameter of the matrix <NUM> to create sufficient sealing force between the rotating shaft <NUM> and the inside diameter of the matrix <NUM>. That is, the process fluid may energize the matrix from the back side. Accordingly, leakage of process fluid may be prevented.

In some examples, the pressure actuating port <NUM> has a diameter <NUM> in the range of <NUM> to <NUM>. Another embodiment of the invention is described below with reference to <FIG>.

<FIG> is a cross-sectional view of a matrix split rotary seal including a pressure actuation port and an anti-rotation element according to a fifth embodiment of the invention. As shown in <FIG>, a rotating shaft <NUM> effects a seal with a radially inner surface of a matrix <NUM>. The matrix <NUM> is energized by an energizer <NUM>, and the matrix <NUM> and energizer <NUM> are provided in a housing <NUM>. Two static sealing surfaces <NUM> formed on a radially outward side of the housing <NUM> effect a seal with a static component <NUM>, in conjunction with a non-integral static sealing element <NUM>. Furthermore, the housing <NUM> may include one or more pressure actuating ports <NUM>.

In general, some sort of anti-rotation feature may be needed to hold the matrix <NUM> to counter rotating frictional forces applied between the shaft and the inside diameter of the matrix <NUM>. The force applied to the matrix <NUM> is the product of the coefficient of friction of the matrix <NUM> and the normal force applied by the energizer <NUM> on the outside diameter of the matrix <NUM>.

In some circumstances, the compression force applied axially to the matrix <NUM> due to interference with the housing <NUM> may be sufficient to prevent the matrix <NUM> from rotating. However, in other circumstances where the compression force is not sufficient to hold the matrix <NUM>, a positive anti-rotational force may be advantageous. Accordingly, an additional anti-rotational element <NUM> may be superimposed to positively capture the matrix <NUM> and prevent the matrix <NUM> from rotating.

The anti-rotational element <NUM> may be one or more pins, staples, or screws applied in a radial fashion to the housing <NUM>. One or more thru-holes may be drilled into the housing <NUM> and an anti-rotational element <NUM> may be applied to the matrix <NUM>. The through holes and the anti-rotational element <NUM> may or may not be threaded. In some embodiments (e.g., as shown in <FIG>), the anti-rotational element <NUM> may extend through the housing <NUM>, the matrix <NUM>, and/or the energizer <NUM> (and other components, if present) in a radial direction. In other embodiments (e.g., see <FIG>), the anti-rotational element <NUM> may extend through one or more of these components in an axial direction.

The anti-rotational element <NUM> may be formed of plastic or polymer. The anti-rotational element <NUM> would typically not be formed of a metal, in order to prevent damage if the anti-rotational element <NUM> comes into contact with the rotating shaft <NUM>.

In addition to providing anti-rotational properties, the anti-rotational element <NUM> also provides matrix attachment while the seal assembly is opened and maneuvered into position during installation.

<FIG> is a close up of the anti-rotation element <NUM> of <FIG>. As shown in <FIG>, the anti-rotation element <NUM> includes a proximal end <NUM> and a distal end <NUM>. During installation, the distal end <NUM> is inserted through the housing <NUM> and the matrix <NUM>. The distal end <NUM> pierces the matrix <NUM> to a predetermined depth, for example <NUM>. Care should be taken so that the distal end <NUM> will not protrude through the end of the matrix, which could cause the anti-rotation element <NUM> to contact the rotating shaft <NUM>, damaging the anti-rotation element <NUM> or the shaft <NUM>. However, the distal end <NUM> of the anti-rotation element <NUM> should extend far enough into the matrix <NUM> so that the anti-rotation element <NUM> can hold the matrix <NUM> in place. Accordingly, a size of the anti-rotation element shaft <NUM> should be selected so that the distal end <NUM> of the anti-rotation element <NUM> can extend from the proximal end <NUM> an appropriate amount. For example, in one embodiment, the shaft <NUM> of the anti-rotation element <NUM> is <NUM> in diameter.

<FIG> is a perspective view of the matrix split rotary seal assembly of <FIG>. As show in <FIG>, the pressure actuating ports <NUM> are spaced approximately every <NUM> along a radially extending face of the housing. One anti-rotation element <NUM> is employed in the example depicted in <FIG>, although more or fewer anti-rotation elements <NUM> may be used, depending on the application.

Another embodiment of the invention employing a fluid leakage collecting channel and a sleeve is shown in <FIG>. As shown in <FIG>, a rotating shaft <NUM> effects a seal with a radially inner surface of a matrix <NUM>. The matrix <NUM> is energized by an energizer <NUM>, and the matrix <NUM> and energizer <NUM> are provided in a housing <NUM>. A static sealing surface <NUM> is formed on a radially outward side of the housing <NUM> and effects a seal with a static component.

In some embodiments, a fluid leakage collecting channel <NUM> may serve as a gutter for collecting expelled fluid in a separate vessel. The channel scavenges any leakage from the interface between the matrix and shaft. The size of the collecting channel can be small relative to the size or the matrix seal footprint. The fluid leakage collecting channel <NUM> may be formed directly in the housing <NUM>.

The anti-rotational element <NUM> and the matrix <NUM> may be allowed to move radially inwardly and outwardly, because the thru-hole in the housing <NUM> may allow movement of the screw. A sleeve <NUM> cut to an appropriate depth that spans from the countersink hole to the outside diameter of the matrix in the housing <NUM> may control the amount the anti-rotational element <NUM> enters into the matrix <NUM>. The anti-rotational element <NUM> and sleeve <NUM> may be made out of plastic materials to reduce any adverse effects if contact is made with the rotating shaft <NUM>.

<FIG> is a cross sectional view of a matrix split rotary seal according to another embodiment of the invention. As shown in <FIG>, a rotating shaft <NUM> effects a seal with a radially inner surface of a matrix <NUM>. The matrix <NUM> is energized by an energizer <NUM>, and the matrix <NUM> and energizer <NUM> are provided in a housing <NUM>. A static sealing surface <NUM> is formed on a radially outward side of the housing <NUM> and effects a seal with a static component.

A fluid leakage collecting channel <NUM> connects to a fluid leakage discharge channel <NUM> formed in the housing <NUM>. The channel <NUM> is positioned at the <NUM> o'clock position in the installation. This allows fluid collected in the channel housing <NUM> to move due to gravity down flow out through channel <NUM>. Electively, a reservoir can be used to collect effluent as opposed to discharging in an uncontrolled manner.

<FIG> depict different types of splits which may be employed in exemplary embodiments of the present invention. Different types of splits can be achieved using manufacturing techniques known in the art. A split configuration provides ease of installation; however, a solid unitary seal without a split may also be provided in some embodiments without deviating from the scope of the appended claims.

The housing, energizer, and sealing element (e.g., a matrix) may be split in an interlocking fashion with a radial configuration. For example, <FIG> is a perspective view of a matrix split rotary seal having a housing <NUM> that is split <NUM> in the form of a "V" cut. <FIG> is a perspective view of a matrix split rotary seal having a housing <NUM> that is split <NUM> in the form of a keyway split or block intercut. An interlocking split like the ones in <FIG> serves to lock two ends of the seal within an equipment bore, preventing misalignment. Once the annular matrix rotary seal assembly is introduced into the annular equipment configuration, the seal is locked and compressed. For example, the two ends may be pressed together.

As an alternative to an interlocking design, the housing, energizer, and sealing element (e.g., a matrix) may be split by a butt or skieve geometry. For example, <FIG> is a perspective view of a matrix split rotary seal having a housing <NUM> that is split <NUM> in the form of a skieve cut. A skieve cut <NUM> has the advantage of allowing system pressure to enhance sealing at the interface in the axial direction.

<FIG> is a flowchart depicting an exemplary method for manufacturing a matrix split rotary seal according to an exemplary embodiment of the invention. The steps described below are exemplary only, and need not be performed in the same order described.

At step <NUM> a housing is provided. The housing may be formed from elastomer, plastic, polyeurethane, or metal, and may be fabricated according to any method suitable for forming the selected material. The housing may be split.

The housing includes a radially interior inside channel, which is defined (in part) by an interior axially extending wall. In addition to the interior axially extending wall, the radially interior inside channel includes two interior radially extending walls.

At a radially interior end of the housing, a radially inner first slanted wall may be formed. The first slanted wall may extend from one of the interior substantially radially extending walls to a meeting point, and a radially inner second slanted wall may extends from the meeting point to a radially extending exterior wall of the housing. The radially inner first slanted wall and the radially inner second slanted wall being slanted away from the axial direction at different angles.

At step <NUM>, one or more thru-holes may be drilled into the housing for seating one or more anti-rotational elements. The thru-holes need not necessarily be drilled, but may be provided using any means for creating a hole in the material selected for the housing. The thru-holes may be drilled in a radial direction from a radially outer end of the housing.

At step <NUM>, one or more sleeves may be formed in the housing. The sleeves may allow the anti-rotational elements inserted into the thru-holes to move radially inwardly and outwardly during operation of the mechanical seal. The sleeves may be shaped to accommodate the anti-rotational elements.

At step <NUM>, one or more pressure actuation passages may be drilled into a radially extending side of the housing. The pressure actuation passages need not necessarily be drilled, but may be provided using any means for creating a hole in the material selected for the housing. The pressure actuation passages may be drilled in an axial direction from one axial end of the housing into the radially interior inside channel of the housing at a location radially lateral to the location where the energizer will be provided (see step <NUM>). The pressure actuation passages may be provided at regular intervals along the radially-extending side of the housing, for example every <NUM> along the circumference of the annular seal.

At step <NUM>, one or more fluid leakage collecting channels and fluid leakage discharge channels may be formed in the housing. The collecting channels would be annular configurations that are adjacent to the matrix. Collecting channels are made to be integral with the housing and can be of any geometry, rectangular being the most basic.

At step <NUM>, an energizer for providing a radial force to a matrix is positioned in the radially interior inside channel of the housing. The energizer may be made up of elastomer, foam, silicone, fluorocarbons, ethylene propylene diene Monomer (M-class) rubber (EPDM), nytrile, a sponge, or a metallic spring. The particular type, shape, and size of the energizer may be selected so that the energizer has a resistive force of <NUM>-<NUM> N/mm. The energizer may be split, and may be in the form of a cord.

At step <NUM> a matrix is provided substantially within the radially interior inside channel of the housing. The matrix may be formed of composite reinforced fibers or yarns and one or more lubricants. The fibers or yarns may be braided or woven in a textile fashion. The fibers may be carbon, aramid, rayon, kynol, Kevlar, cotton, or polytetrafluoroethylene (PTFE) fibers, or a combination. The lubricants may include carbon, graphite, and PTFE based lubricants.

The matrix is configured and positioned such that the matrix (when deployed in conjunction with an energizer) protrudes from the radially interior inside channel. The matrix has a radially inner surface for sealing against the equipment. The matrix is positioned such that the energizer is disposed between the matrix and the interior axially extending wall in the radial direction. The matrix may be split, and may be in the form of a cord.

The matrix may be selected so that the matrix has an inner diameter and the housing has an inner diameter defined at the radially innermost point of the housing, and the inner diameter of the matrix is less than the inner diameter of the housing. The matrix may also be selected to be more rigid than the energizer.

At step <NUM>, one or more anti-rotational elements may be inserted into the through-holes and pushed through the energizer and at least a part of the matrix. The anti-rotational elements may be screws or pins, and may be formed, for example, from plastic.

At step <NUM>, one or more static sealing elements may be provided on a radially outer surface of the housing. The static sealing elements may be formed integrally with the housing. Alternatively, a radially exterior outside channel may be formed in the housing, and a non-integral static sealing element, such as an o-ring, may be provided in the radially exterior outside channel. If one or more thru-holes and anti-rotational elements were provided at step <NUM>, the sealing elements may be provided so as to cover a proximal end of the anti-rotational elements.

<FIG> depict another embodiment not part of the present invention. In this embodiment, multiple anti-rotational elements are present. <FIG> is a perspective view of the seal assembly from a first side, while <FIG> is a perspective view of the seal assembly from a second side opposite the first side. <FIG> is a close-up view of the second side of the seal assembly. <FIG> and <FIG> are cross-sectional views of the seal assembly.

In the embodiment of <FIG>, a first set of anti-rotational elements (energizer pins, in one embodiment) may extend through the housing and the energizer of the seal assembly at one or more locations along a circumference at a radial distance r<NUM> from the center of the shaft so as to extend through the energizer substantially at the center of the energizer. A second set of anti-rotational elements (sealing element pins, in one embodiment) may extend through the housing and the matrix of the seal assembly at one or more locations along a circumference at a radial distance r<NUM> from the center of the shaft so as to extend through the matrix substantially at the center of the matrix.

It should be noted that the anti-rotational elements need not extend through the energizer or the matrix at precisely the center, and in other embodiments one or more pins may be provided which pass through each of these elements at the center and/or at locations offset from the center of these elements.

In view of the above, it will be seen that the invention efficiently attains the objects set forth above, among those made apparent from the preceding description.

Claim 1:
An annular seal assembly for sealing against a rotating shaft extending in an axial direction, wherein a radial direction extends outward from the shaft perpendicular to the axial direction, the seal assembly comprising:
a housing (<NUM>, <NUM>) comprising a radially interior inside channel, the radially interior inside channel being defined by an interior axially extending wall and two interior radially extending walls;
a matrix (<NUM>, <NUM>) provided substantially within the radially interior inside channel of the housing and protruding from the radially interior inside channel, the matrix having a radially inner surface for sealing against the shaft; and
an energizer (<NUM>, <NUM>) for providing a radial force to the matrix, wherein the energizer is disposed in the radially interior inside channel of the housing between the matrix and the interior axially extending wall in the radial direction, and wherein the energizer contacts the matrix and the interior axially extending wall and the two interior radially extending walls of the radially interior inside channel when compressed, and
wherein the matrix contacts the two interior radially extending walls and the energizer in addition to the shaft, characterized in that the seal assembly comprises an anti-rotational mechanism to prevent the matrix from rotating with the shaft, wherein the anti-rotational mechanism comprises an anti-rotational element (<NUM>, <NUM>) for preventing the matrix from rotating, the anti-rotational element extending through the housing and energizer and into the matrix.