Patent Description:
According to other known techniques, the mechanical seal employs additional sealing elements, such as annular O-rings, to help seal process fluid within the mechanical seal. A drawback of these conventional annular sealing elements is that they do not completely seal fluid or do not fully fill the space or groove that seats the sealing element. In certain commercial environments, such as those where it is essential that no micro bacterial growth occurs, this is unacceptable. To address this shortcoming, specially designed sealing elements were formed using conventional molding techniques. For example, the sealing elements are manufactured by shaping liquid raw material using a rigid frame called a mold. However, these conventional molding techniques are expensive and time consuming to manufacture the appropriate sealing element.

<CIT> describes a method of making gaskets.

The present invention is directed to a mechanical seal for mounting about a shaft, comprising a holder assembly having a main body having an inner surface and an opposed outer surface, and a first groove formed in the inner surface of the holder assembly and a second groove formed in the inner surface of the holder assembly, a rotary seal ring coupled to the holder assembly, a stationary seal ring disposed adjacent to the rotary seal ring, a first sealing element for seating within the first groove and having a shape that is substantially complementary to a shape of the first groove so as to fill substantially completely the first groove, and a second sealing element for seating within the second groove and having a shape that is substantially complementary to a shape of the second groove so as to fill substantially completely the second groove. Further, the main body of the holder assembly has one or more fastener-receiving apertures formed therein and extending between the inner surface and the outer surface and being sized and configured for seating a fastener.

In some embodiments, the mechanical seal employs a sealing cover element that is configured for overlying or covering the fastener-receiving aperture formed in the holder assembly, thus forming a fluid tight seal. The sealing cover element has leg portions that seat within grooves that are disposed on both sides of the fastener-receiving aperture so as to secure the sealing cover element to the holder assembly.

Also described herein, but not forming part of the present invention, is a method of forming a sealing element for a mechanical seal, comprising winding a source of elastomer material, heating the elastomer material to form a homogenous elastomer material, coating the homogenous elastomer material with a resin material, placing the resin coated elastomer material into a turning machine, forming the outer profile and shape of the sealing element into the shaped resin coated elastomer material, and cutting the sealing elements from the shaped resin coated elastomer material.

The elastomer material can include any of ethylene propylene (EP), ethylene propylene diene methylene (EPDM), fluoroelastomers including FKM and FPM as defined by the ASTM International standard D1418, perfluoroelastomers including FFKM, and tetrafluoroethylene-propylene rubber including FEPM. Further, the elastomer material has a hardness between about <NUM> Shore A and about <NUM> Shore A.

Also described herein, but not forming part of the present invention, is a system for forming a sealing element for a mechanical seal, comprising a source of elastomer material, a winding machine for winding the elastomer material, a heating unit having one or more heating elements for heating the elastomer material to form a homogenous elastomer material, a coating unit for coating the homogenous elastomer material with a resin material, a turning machine for forming the outer profile and shape of the sealing element into the shaped resin coated elastomer material, and a cutting unit for cutting the sealing element from the shaped resin coated elastomer material. The system can also include an electronic device for communicating with and controlling one or more of the winding machine, the heating unit, the coating unit, the turning machine, and the cutting unit. The electronic device comprises a processor and a memory element.

The turning machine can include one or more cutting elements for forming the profile in the shaped resin coated elastomer material.

With regard to the holder assembly, the assembly may also include first and second cover grooves formed in the outer surface of holder assembly, wherein the first cover groove is formed on one side of the fastener-receiving aperture and the second cover groove is formed on the other side of the fastener-receiving aperture, and a sealing cover element having a main body having a first leg portion, an opposed second leg portion, and an intermediate portion disposed between and coupled to the first and second leg portions. The first leg portion of the sealing cover element is sized and configured for seating within the first groove, the second leg portion of the sealing cover element is sized and configured for seating within the second groove, and the intermediate portion of the sealing cover element covers the fastener-receiving aperture.

Preferably, the first leg portion is sized and configured so as to fill substantially completely the first cover groove, and the second leg portion is sized and configured so as to fill substantially completely the second cover groove.

Preferably, the intermediate portion of the sealing cover element has a top surface and an opposed bottom surface, and the first and second leg portions each have a top surface and an opposed bottom surface. The top surface of the intermediate portion is radially spaced from the top surface of the first and second leg portions. Further, the bottom surface of the first and second leg portions is radially spaced from the bottom surface of the intermediate portion.

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 throughout 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 and, in some embodiments, a sealing cover element for providing sealing of a set screw aperture formed in a holder assembly of a mechanical seal as well as additional sealing elements for providing a fluid tight seal at selected seal locations. The present 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.

The term "shaft" as used herein 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" as 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. The terms "fluid" and "fluids" refer to liquids, gases, and combinations thereof.

The term "axially inner" as used herein refers to that portion of the stationary equipment and/or components of a mechanical seal that are disposed proximate to the stationary equipment (e.g., mechanical system) employing the mechanical seal. As such, this term also refers to the components of the mechanical seal that are mounted to or within the stationary equipment or are disposed the deepest within or closest to the equipment (e.g., inboard). Conversely, the term "axially outer" as used herein refers to the portion of stationary equipment and the mechanical seal that is disposed distal from (e.g., outboard) of the mechanical seal.

The term "radially inner" as used herein refers to the portion of the mechanical seal or associated components that are proximate to a shaft. Conversely, the term "radially outer" as used herein refers to the portion of the mechanical seal or associated components that are distal from the shaft.

The terms "stationary equipment" and/or "static surface" as used herein are intended to include any suitable stationary structure housing a shaft or rod to which a seal having a gland is secured. Those of ordinary skill will also recognize that the gland assembly can form part of the mechanical seal or part of the stationary equipment.

The terms "process medium" and/or "process fluid" as used herein generally refer to the medium or fluid being transferred through the stationary equipment. In pump applications, for example, the process medium is the fluid being pumped through the pump housing.

The term "gland" as used herein is intended to include any suitable structure that enables, facilitates or assists securing the mechanical seal to the stationary equipment, while concomitantly surrounding or housing, at least partially, one or more seal components. If desired, the gland can also provide fluid access to the mechanical seal.

The term "mechanical seal" as used herein is intended to include various types of mechanical seals, including single seals, split seals, tandem seals, dual seals, concentric seals, gas seals, spiral seals, solid seals, split seals and other known seal types and configurations.

As shown in <FIG>, the mechanical seal <NUM> of the present invention comprises an annular holder assembly <NUM>, an annular rotary seal ring <NUM>, an annular stationary seal ring <NUM>, and additional annular sealing elements, all of which are disposed about a shaft <NUM>. The holder assembly <NUM> is typically disposed within an annular gland (not shown), which is secured to stationary equipment, as is known in the art. The rotary seal ring <NUM> has a sealing surface <NUM> that is configured to be disposed in sealing contact with a sealing surface <NUM> of the stationary seal ring <NUM>. The mechanical seal <NUM> also includes one or more biasing elements, such as springs <NUM>, that are mounted between a back side or rear portion of the rotary seal ring <NUM> and an inner radial stepped surface of the holder assembly <NUM> for providing a biasing force to the rear portion of the rotary seal ring <NUM>.

The illustrated holder assembly <NUM> includes a main body <NUM> having an inner surface <NUM> and an outer surface <NUM>. The inner surface <NUM> has an inner fastener or set screw aperture <NUM> formed therein for seating a fastener, such as a pin or a set screw <NUM>. The pin or set screw <NUM> helps couple the rotary seal ring <NUM> to the holder assembly <NUM>. The inner surface <NUM> also has formed therein an innermost sealing groove <NUM> that is sized and configured for seating a sealing element <NUM>. The sealing element <NUM> provides a fluid-tight seal between the axially innermost portion of the holder assembly <NUM> and the shaft <NUM>. The inner surface <NUM> also includes an axially outermost sealing groove <NUM> for seating a sealing element <NUM>. The sealing element <NUM> provides a seal between the holder assembly <NUM> and a radially outer surface of the rotary seal ring <NUM>. An additional sealing element <NUM> can be employed to provide sealing about an upper portion of the stationary seal ring <NUM>.

The main body <NUM> of the holder assembly <NUM> also includes a fastener-receiving aperture <NUM> that is formed between the outer surface <NUM> and the inner surface <NUM> thereof. Specifically, the fastener-receiving aperture <NUM> fully extends between the inner and outer surfaces of the holder assembly <NUM>. The fastener-receiving aperture <NUM> is sized and configured for seating a fastener, such as a set screw <NUM>. The outer surface <NUM> of the main body <NUM> further comprises a pair of sealing element grooves <NUM>, <NUM> that are disposed on either side of the fastener-receiving aperture <NUM> and hence are axially spaced apart along the outer surface <NUM>. The grooves <NUM>, <NUM> are preferably disposed relatively adjacent to the fastener-receiving aperture <NUM>. The grooves are sized and configured for seating a portion of an annular sealing cover element <NUM>. According to one embodiment, the holder assembly <NUM> can have a plurality of fastener-receiving apertures <NUM> formed therein. The set screws <NUM> help position and mount the mechanical seal <NUM> at one or more selected positions, and help mechanically couple the holder assembly <NUM> to the shaft <NUM>. The sealing cover element <NUM> helps minimize or prevent process fluid from leaking past the set screw <NUM> through the aperture <NUM>.

As shown in <FIG>, the groove <NUM> includes a groove bottom or floor <NUM> and a pair of opposed groove sidewalls 44A, 44B. Similarly, the groove <NUM> includes a groove floor <NUM> and a pair of opposed sidewalls 54A, 54B. The sidewalls of the grooves <NUM>, <NUM> can be configured so as to be generally straight (i.e., generally vertical or radially extending) or can be angled relative to an elongated axis of the holder assembly <NUM>. The grooves <NUM>, <NUM> can be identical in size and shape or can be differently configured.

As shown in <FIG>, the sealing cover element <NUM> has a main body <NUM> that has a pair of opposed leg portions <NUM>, <NUM> that are coupled together by an intermediate portion <NUM>. The leg portions <NUM>, <NUM> are formed at opposed ends of the sealing cover element <NUM>. The intermediate portion <NUM> has a top surface <NUM> that is spaced both axially and radially (e.g., horizontally and vertically) from a top surface <NUM> of the leg portions <NUM>, <NUM>. Similarly, a bottom surface <NUM> of the intermediate portion <NUM> is spaced both axially and radially (e.g., both horizontally and radially) from the bottom surfaces <NUM> of the leg portions <NUM>, <NUM>. Each of the leg portions <NUM>, <NUM> also includes sidewalls. For example, the leg portion <NUM> includes opposed sidewalls 132A, 132B and the leg portion <NUM> includes opposed sidewalls 134A, 134B. The opposed sidewalls meet the bottom surface <NUM> to form corner or edge portions that can be relatively straight (e.g., at <NUM> degree angles) or can be rounded or curved. The leg portions <NUM>, <NUM> can have dimensions that are slightly larger than the dimensions of the groves <NUM>, <NUM> such that the leg portions when seated within the grooves form a frictional or mechanical fit. Moreover, the intermediate portion <NUM> has a length that corresponds to the axial distance between the grooves <NUM>, <NUM>. The sealing cover element <NUM> can be made of any suitable resilient material, and can be formed from an elastomer material.

In operation, the mechanical seal <NUM> of the present invention can be assembled and then mounted to the stationary equipment (not shown). When assembled, the rotary seal ring <NUM> is coupled to the holder assembly <NUM> by the pin or set screw <NUM>. The holder assembly <NUM> is then axially positioned along the shaft <NUM> of the stationary equipment and tightened relative thereto using the set screws <NUM>. To avoid any leakage passing the set screws <NUM>, the sealing cover element <NUM> is placed over the set screws <NUM> and corresponding fastener-receiving apertures <NUM>, thus forming a fluid-tight seal. In order to prevent the sealing cover element <NUM> from being accidentally removed or spun off of the mechanical seal <NUM> when the shaft rotates at higher speeds, the sealing cover element <NUM> can be stretched over the set screws <NUM>. Specifically, the leg portion <NUM> seats within the groove <NUM> and the leg portion <NUM> seats within the groove <NUM>. When the leg portions <NUM>, <NUM> are seated or pressed within the grooves <NUM>, <NUM>, the intermediate portion <NUM> of the sealing cover element <NUM> spans or extends between the grooves <NUM>, <NUM> and covers the fastener-receiving apertures <NUM> and the set screws <NUM> mounted therein. That is, the bottom surface <NUM> of the leg portion <NUM> contacts the floor <NUM> of the groove <NUM>, and the sidewalls 132A, 132B of the leg portion <NUM> contact the sidewalls 54A, 54B, respectively, of the groove <NUM>. Likewise, the bottom surface <NUM> of the leg portion <NUM> contacts the floor <NUM> of the groove <NUM>, and the sidewalls 134A, 134B of the leg portion <NUM> contact the sidewalls 44A, 44B, respectively, of the groove <NUM>. The mounting or seating arrangement of the sealing cover element <NUM> helps prevent fluid from passing or leaking past the thread holes of the set screw aperture <NUM> and associated set screws <NUM>. The leg portions <NUM>, <NUM> of the sealing cover element <NUM> are axially squeezed when mounted within the grooves <NUM>, <NUM> so as to avoid any potential leakage from the set screws, thus attaining a substantially fluid-tight and crevice-free design.

Further, the holder assembly <NUM> can be configured such that the sealing cover element <NUM> can be mounted on the inner surface <NUM> of the main body <NUM> thereof rather than on the outer surface <NUM>, as shown. In this embodiment, the grooves <NUM>, <NUM> are formed on the inner surface <NUM> on either side of the fastener-receiving aperture <NUM>. The grooves <NUM>, <NUM> can be configured such that the leg portions <NUM>, <NUM> of the sealing cover element <NUM> are axially squeezed into the grooves. The sidewalls of the grooves <NUM>, <NUM> are configured so as to be generally straight (i.e., generally vertical or radially extending) or can be angled relative to an elongated axis of the holder.

Based on the design and configuration of the sealing cover element <NUM>, the sealing cover element is able to meet the space constraint requirements of the mechanical seal <NUM> and associated stationary equipment. Moreover, the sealing cover element <NUM> in combination with other sealing elements serve to create a crevice-free environment, which is essential for applications where micro bacterial grow is not permitted.

Also described herein, but not forming part of the present invention, is a system and method of forming or creating the sealing elements to form a substantially crevice free design. That is, the sealing elements can be formed so as to fill substantially completely the groove or channel that seats the sealing elements. According to one practice, the term "substantially completely" is intended to mean filling the groove or channel with the sealing element such that greater than <NUM>% of the groove or channel is filled solely by the sealing element, and preferably greater than <NUM>%. One of ordinary skill in the art will be readily able to determine based on the teachings herein and based on the application or environment of the mechanical seal the percentage of the groove or channel that needs to be filled with the sealing element so as to reduce to the extent possible the unfilled portions of the groove. Further, the sealing elements can have any selected shape and size, and are preferably not circular or oval in shape.

In order to employ sealing elements, such as the sealing elements <NUM> and <NUM>, and if desired the sealing cover element <NUM>, that accommodate and seat fully within their respective channels or grooves to form a crevice-free design, they typically need to be specially formed and configured. The specially configured sealing elements are preferably configured or shaped (e.g., complementary in shape) to the selected shape and contours of the corresponding groove. The annular sealing elements <NUM> and <NUM>, as well as if desired any of the other sealing elements of the mechanical seal <NUM>, can be formed from an elastomer material. The annular sealing elements are preferably machined from an elastomer source material that includes for example elastomer tubes. The formation process allows for much higher flexibility, responsiveness and reduction of tooling costs.

The mechanical seal <NUM> of the present invention employs specially designed and configured sealing elements, such as sealing elements <NUM> and <NUM>, having varying contours and shapes designed to significantly reduce or eliminate any potential spaces or crevices in the channels or grooves that seat the sealing elements. The specially formed and shaped sealing elements are installed where conventional O-rings or sealing elements are traditionally used. When employing conventional sealing elements, there are typically spaces or gaps of unwanted sizes within the channel that can make the conventional sealing elements unsuitable for their intended purpose. The sealing elements of the present invention are machined from a source sealing material, such as elastomer tubes, to ensure maximum manufacturing flexibility. The sealing elements of the present invention are configured to substantially the same shape and size of the channel or grooves and are designed to be radially and/or axially squeezed within the respective grooves depending on the shape and contours of the particular sealing element, imbedded groove shape and/or equipment design. The sealing elements hence serve to minimize, reduce or eliminate any potential crevices such that no micro-bacterial growth may occur. This crevice-free design also allows easier and thorough cleaning of the mechanical seal <NUM>.

The sealing element <NUM> of the present invention is sized and configured for seating substantially completely within the corresponding groove or channel <NUM>, and the sealing element <NUM> is sized and configured for seating substantially completely within the groove <NUM>. The sealing elements <NUM>, <NUM> and <NUM> can be made from a relatively soft or resilient elastomer material. Specifically, the typical hardness of the elastomer material varies from between about <NUM> Shore A and about <NUM> Shore A. Typical elastomer materials suitable for use herein can include for example synthetic elastomers including ethylene propylene (EP) and ethylene propylene diene methylene (EPDM), which is a type of synthetic rubber; fluoroelastomers including FKM and FPM as defined by the ASTM International standard D1418; perfluoroelastomers including FFKM; and tetrafluoroethylene-propylene rubber including FEPM.

As shown in <FIG>, a sealing element formation system <NUM> for forming or creating an annular sealing element for use with the mechanical seal <NUM> is described. The formation system <NUM> includes a material source <NUM> that includes a source of the elastomer material. The elastomer material is then conveyed or transferred to a winding machine <NUM> so that the source material can be wound into any suitable shape, and can include a generally elongated tubular shape having a round, oval, square or rectangular cross-section. The tubes preferably have a rectangular cross-section before machining. The winding machine <NUM> can be any conventional winding machine as is known in the art. The tube of source material is then exposed to heat from a heating unit <NUM> for heating the source material tube to a selected temperature for a selected period of time. The heating unit <NUM> can be any known type of heating unit that employs one or more heating elements. For example, the heating unit <NUM> can be a resistive heating unit or any other known and suitable type of heating unit. The source material tube is heated by the heating unit to a selected temperature or temperature range so as to form a generally and substantially homogeneous product. The temperature or temperature range as well as the duration of heating can vary based on the type of source material employed by the system <NUM> and the type of mechanical seal <NUM>. The heated source material tube can then be coated with a suitable coating material by the coating unit <NUM>. The coating material can be any suitable material, such as a resin material, such that when the heated source material is coated, the coated material is sufficiently stiff for subsequent machining on any conventional chipping machine.

The coated material thus has an outer resin layer that can then be secured, such as by clamping, into a conventional turning or lathing machine <NUM>. The turning machines are standard machines in the relevant industries and need not be described further herein. The turning machine can include a relatively sharp, hard metal turning or cutting tool (not shown) that can be used to machine or cut any type of contour into the generally rectangular elastomer tube. The turning is preferably done by cutting or chipping material away from the tube until the dimensions and contours of the tube match the requirements of the sealing elements necessary for the specific channel design. The turning machine <NUM>, and any of the other relevant portions of the formation system <NUM>, can be coupled to an electronic device <NUM> that can be used to control the operation of any selected portion of the formation system <NUM>. For example, the electronic device can be used to control one or more of the winding machine <NUM>, the heating unit <NUM>, the coating unit <NUM> and/or the turning machine <NUM>. The electronic device <NUM> can be a computer, a server, a tablet, a smart phone or the like. As is known in the art, the electronic device <NUM>, in addition to other elements such as a display, user interface, and input elements (e.g., keyboard, mouse, and the like), can include a processor <NUM> and a storage or memory element <NUM>. The memory element <NUM> can store any selected application and software suitable for communicating with and/or operating one or more of the components of the system <NUM>. For example, the turning machine <NUM> can communicate with the electronic device <NUM> which can have stored thereon software instructions for operating the turning machine so as to cut or turn the material into any predetermined and pre-stored shape.

The illustrated formation system <NUM> also includes a cutting unit <NUM> that can include one or more cutting elements suitable for cutting the material. The cutting unit <NUM> can be employed to cut the turned material into the individual annular or ring-like sealing elements. The cutting of the turned material by the cutting unit <NUM> can be done by a chip less process that employs a relatively sharp cutting tool. The cutting unit employing the cutting tool can form part of the turning machine <NUM> or can be a separate component that forms part of the cutting unit <NUM>.

In operation, as shown in <FIG>, the sealing element formation system <NUM> can provide the source material, step <NUM>, via the material source unit <NUM>. The material is preferably an elastomer material that can be provided or supplied in any selected form, such as sheets. The elastomer source material is then wound into elongated structures or tubes, step <NUM>, by the winding machine <NUM>. The elastomer tubes are then heated to form a substantially homogeneous product for a selected period of time, step <NUM>.

The heated source material tube can then be coated with a suitable coating material by the coating unit <NUM>, step <NUM>. The coating material can be any suitable material, such as a resin material, such that when the heated source material is coated, the coated material is sufficiently stiff for subsequent machining on any conventional chipping or lathing machine.

The outer resin layer allows the coated material to be secured in and to be processed by the turning or lathing machine <NUM>. The turning machine <NUM> can be employed to machine or cut any type of contour into the generally rectangular elastomer source material. The turning is preferably done by machining, carving, cutting or chipping material away from the tube until the outer dimensions and contours (e.g., profile) of the tube relatively match or are complementary in shape with the specific dimensions of the channel or groove, step <NUM>. For example, the coated material can be processed or machined along the outer surface so as to create the cross-sectional profile of the sealing elements <NUM>, <NUM> and <NUM>.

The illustrated formation system <NUM> can also include a cutting unit <NUM>, which can be integrated into the turning machine <NUM> or can be a separate and distinct unit <NUM>, that includes one or more cutting elements suitable for cutting the material. The cutting unit <NUM> can be employed to cut the turned material into the individual annular or ring-like sealing elements, step <NUM>.

Claim 1:
A mechanical seal (<NUM>) for mounting about a shaft, comprising
a holder assembly (<NUM>) having a main body (<NUM>) having an inner surface (<NUM>) and an opposed outer surface (<NUM>), and a first groove (<NUM>) formed in the inner surface of the holder assembly and a second groove (<NUM>) formed in the inner surface of the holder assembly,
a rotary seal ring (<NUM>) coupled to the holder assembly,
a stationary seal ring (<NUM>) disposed adjacent to the rotary seal ring (<NUM>),
a first sealing element (<NUM>) for seating within the first groove (<NUM>) and having a shape that is substantially complementary to a shape of the first groove so as to fill substantially completely the first groove, and
a second sealing element (<NUM>) for seating within the second groove (<NUM>) and having a shape that is substantially complementary to a shape of the second groove so as to fill substantially completely the second groove,
wherein the main body (<NUM>) of the holder assembly (<NUM>) has one or more fastener-receiving apertures (<NUM>) formed therein and extending between the inner surface (<NUM>) and the outer surface (<NUM>) and being sized and configured for seating a fastener (<NUM>).