Sealing cover element in a mechanical seal

A mechanical seal that includes a holder assembly having a fastener-receiving aperture formed therein and having a pair of grooves disposed on either side of the fastener-receiving aperture. A sealing cover element is disposed over the fastener-receiving aperture and has opposed leg portions that seat within the groove.

BACKGROUND OF THE INVENTION

In conventional mechanical seals, the holder portion of the mechanical seal is typically secured, such as by clamping, between an impeller and a shaft of commercial equipment, such as for example a pump, so as to reduce the number of crevices in the seal. This helps reduce unwanted leakage of process fluid from the pump. However, this securing technique requires field personnel to modify the design of the mechanical seal by introducing the securing mechanism. This can compromise the overall sealing integrity of the mechanical seal.

SUMMARY OF THE INVENTION

The present invention is directed to a mechanical seal that employs a sealing cover element that is configured for overlying or covering a fastener-receiving aperture formed in a holder assembly, thus forming a fluid tight seal. The sealing cover element110has 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.

According to one aspect, the present invention includes a mechanical seal for mounting about a shaft, comprising a holder assembly, a rotary seal ring coupled to the holder assembly, and a stationary seal ring disposed adjacent to the rotary seal ring. The holder assembly includes a main body that has an inner surface and an opposed outer surface, and one or more fastener-receiving apertures that extends between the inner surface and the outer surface and is sized and configured for seating a fastener. The holder assembly also includes first and second grooves formed in the outer surface, where the first groove is formed on one side of the fastener-receiving aperture and the second groove is formed on the other side of the fastener-receiving aperture.

The mechanical seal also includes 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.

According to another aspect, 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. Also, the bottom surface of the first and second leg portions is radially spaced from the bottom surface of the intermediate portion. The sealing cover element is formed from an elastomer material and preferably has an annular shape.

According to another embodiment, the inner surface of the holder assembly includes a first sealing groove for seating a first sealing element and an axially spaced second sealing groove for seating a second sealing element. The first sealing groove is formed on one side of the fastener-receiving aperture and the second sealing groove is formed on the other side of the fastener-receiving aperture. Thus, in operation, the first sealing element is positioned for contacting the shaft and the second sealing element is positioned for contacting the stationary seal ring.

DETAILED DESCRIPTION

The present invention provides a sealing cover element for providing sealing of a set screw aperture formed in a holder assembly of a mechanical seal. 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 inFIGS. 1-3, the mechanical seal10of the present invention comprises an annular holder assembly20, an annular rotary seal ring90, an annular stationary seal ring100, and additional annular sealing elements, all of which are disposed about a shaft12. The holder assembly20is typically disposed within an annular gland (not shown), which is secured to stationary equipment, as is known in the art. The rotary seal ring90has a sealing surface92that is configured to be disposed in sealing contact with a sealing surface102of the stationary seal ring100. The mechanical seal10also includes one or more biasing elements, such as springs84, that are mounted between a back side or rear portion of the rotary seal ring90and an inner radial stepped surface of the holder assembly20for providing a biasing force to the rear portion of the rotary seal ring90.

The illustrated holder assembly20includes a main body22having an inner surface24and an outer surface26. The inner surface24has an inner set screw aperture28formed therein for seating a fastener, such as a pin or a set screw30. The pin or set screw30helps couple the rotary seal ring90to the holder assembly20. The inner surface24also has formed therein an innermost sealing groove32that is sized and configured for seating a sealing element80. The sealing element80provides a fluid-tight seal between the axially innermost portion of the holder assembly20and the shaft12. The inner surface24also includes an axially outermost sealing groove34for seating a sealing element82. The sealing element82provides a seal between the holder assembly20and a radially outer surface of the rotary seal ring90. An additional sealing element88can be employed to provide sealing about an upper portion of the stationary seal ring100.

The main body22of the holder assembly20also includes a fastener-receiving aperture36that is formed between the outer surface26and the inner surface24thereof. Specifically, the fastener-receiving aperture38fully extends between the inner and outer surfaces of the holder assembly20. The fastener-receiving aperture36is sized and configured for seating a fastener, such as a set screw38. The outer surface26of the main body22further comprises a pair of sealing element grooves40,50that are disposed on either side of the fastener-receiving aperture36and hence are axially spaced apart along the outer surface26. The grooves40,50are preferably disposed relatively adjacent to the fastener-receiving aperture36. The grooves are sized and configured for seating a portion of an annular sealing cover element110. According to one embodiment, the holder assembly20can have a plurality of fastener-receiving apertures36formed therein. The set screws38help position and mount the mechanical seal10at one or more selected positions, and help mechanically couple the holder assembly20to the shaft12. The sealing cover element110helps minimize or prevent process fluid from leaking past the set screw38through the aperture36.

As shown inFIGS. 1-2, the groove40includes a groove bottom or floor42and a pair of opposed groove sidewalls44A,44B. Similarly, the groove50includes a groove floor52and a pair of opposed sidewalls54A,54B. The sidewalls of the grooves40,50can 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 assembly20. The grooves40,50can be identical in size and shape or can be differently configured.

As shown inFIG. 3, the sealing cover element110has a main body112that has a pair of opposed leg portions116,118that are coupled together by an intermediate portion114. The leg portions116,118are formed at opposed ends of the sealing cover element110. The intermediate portion114has a top surface120that is spaced both axially and radially (e.g., horizontally and vertically) from a top surface122of the leg portions116,118. Similarly, a bottom surface126of the intermediate portion114is spaced both axially and radially (e.g., both horizontally and radially) from the bottom surfaces128of the leg portions116,118. Each of the leg portions116,188also includes sidewalls. For example, the leg portion116includes opposed sidewalls132A,132B and the leg portion118includes opposed sidewalls134A,134B. The opposed sidewalls meet the bottom surface128to form corner or edge portions that can be relatively straight (e.g., at 90 degree angles) or can be rounded or curved. The leg portions118,118can have dimensions that are slightly larger than the dimensions of the groves40,50such that the leg portions when seated within the grooves form a frictional or mechanical fit. Moreover, the intermediate portion114has a length that corresponds to the axial distance between the grooves40,50. The sealing cover element110can be made of any suitable resilient material, and can be formed from an elastomer material.

In operation, the mechanical seal10of the present invention can be assembled and then mounted to the stationary equipment (not shown). When assembled, the rotary seal ring90is coupled to the holder assembly20by the pin or set screw30. The holder assembly20is then axially positioned along the shaft12of the stationary equipment and tightened relative thereto using the set screws38. To avoid any leakage passing the set screws38, the sealing cover element110is placed over the set screws38and corresponding fastener-receiving apertures36, thus forming a fluid-tight seal. In order to prevent the sealing cover element110from being accidentally removed or spun off of the mechanical seal10when the shaft rotates at higher speeds, the sealing cover element110can be stretched over the set screws38. Specifically, the leg portion116seats within the groove50and the leg portion118seats within the groove40. When the leg portions116,118are seated or pressed within the grooves40,50, the intermediate portion114of the sealing cover element110spans or extends between the grooves40,50and covers the fastener-receiving apertures36and the set screws38mounted therein. That is, the bottom surface128of the leg portion116contacts the floor52of the groove50, and the sidewalls132A,132B of the leg portion116contact the sidewalls54A,54B, respectively, of the groove50. Likewise, the bottom surface128of the leg portion118contacts the floor42of the groove40, and the sidewalls134A,134B of the leg portion118contact the sidewalls44A,44B, respectively, of the groove40. The mounting or seating arrangement of the sealing cover element110helps prevent fluid from passing or leaking past the thread holes of the set screw aperture36and associated set screws38. The leg portions116,188of the sealing cover element110are axially squeezed when mounted within the grooves40,50so as to avoid any potential leakage from the set screws, thus attaining a substantially fluid-tight and crevice-free design.

Further, the holder assembly20can be configured such that the sealing cover element110can be mounted on the inner surface24of the main body22thereof rather than on the outer surface26, as shown. In this embodiment, the grooves40,50are formed on the inner surface24on either side of the fastener-receiving aperture36. The grooves40,50can be configured such that the leg portions116,188of the sealing cover element110are axially squeezed into the grooves. The sidewalls of the grooves40,50are 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 element110, the sealing cover element is able to meet the space constraint requirements of the mechanical seal10and associated stationary equipment. Moreover, the sealing cover element110in combination with other sealing elements serve to create a crevice-free environment, which is essential for applications where micro bacterial grow is not permitted.

It will thus be seen that the invention efficiently attains the objects set forth above, among those made apparent from the preceding description. Since certain changes may be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.