Patent Application
20160178057
The present disclosure relates to seal devices and more particularly to a seal device and method for forming a seal device that provides a visual indication of seal integrity, or lack thereof.
Seals are used in numerous applications to prevent a fluid from leaking between two structures. Fluid seals are made of a variety of materials and have a multitude of design configurations. Such seals may begin to fail when exposed to high temperatures or pressures.
U.S. Pat. No. 5,501,945 to Kanakkanatt discloses using dyes in packaging materials that respond to specific stimuli and indicate exposure to stimuli by a change or shift in the frequencies of light which they adsorb. Although the methods disclosed by Kanakkanatt include use of photochromic, chemichromic, or piezochromic dyes to indicate specific changes in the environment of the packaging materials, Kanakkanatt does not disclose using such dyes to detect seal failures for mechanical components. Instead, the dyes are used for verification of heat seal quality to detect whether a packaged food or medical use product has been properly sealed.
The disclosed devices and methods are directed to solve one or more of the problems set forth above and/or other problems in the art.
In one embodiment, a seal device is provided. The seal device includes a seal member configured to seal a first component and a second component and a tab member formed on a seal member perimeter. The tab member is configured to extend substantially outward from the seal member perimeter to a respective component perimeter. The seal member and the tab member are formed from a mixture of a seal compound and a characteristic changing compound. The tab member is configured to provide a visual indication of seal integrity without separating the first component and the second component.
In one embodiment, method for visually indicating seal integrity is provided. The method includes mixing a seal compound and a characteristic changing compound. The method further includes forming a seal device using the mixture of the seal compound and the characteristic changing compound. Forming the seal device includes forming a seal member configured to seal a first component and a second component and forming a tab on a seal member perimeter. The tab is configured to extend substantially outward from the seal member perimeter to a respective component perimeter. The tab and the characteristic changing compound provide a visual indication of seal integrity without separating the first and second sealed components.
In one embodiment, a seal device is provided. The seal device includes a seal member configured to seal a first component and a second component. The seal device further includes a tab member formed on a seal member perimeter. The tab member is configured to extend substantially outward from the seal member perimeter to a respective component perimeter and fit within a corresponding tab channel formed within at least one of the first component and the second component. The seal member and the tab member are formed from a mixture of a seal compound, a pressure sensitive compound, and a temperature sensitive compound. The tab member is configured to provide a visual indication of seal integrity without separating the first component and the second component.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several aspects of the disclosure and together with the description, serve to explain the principles of the disclosure. In the drawings:
Referring now to
The seal member 12a may generally be formed having a length and a cross section that may be generally uniform along the length of the seal member 12a, though minor dimensional changes of the cross section may occur due to normal manufacturing variability. The seal member 12a may generally include an outer perimeter and an inner perimeter. The seal member 12a may have a multitude of design configurations that include, but are not limited to, an elastomeric O-ring seal, a press-in-place seal, an H-type seal, a washer made of a soft conformable material, a flat gasket made from a soft conformable material, a compression fitting, a circular flared fitting, a threaded pipe fitting, etc. Sealing using conformable materials may be achieved when such material is placed between relatively rigid mating surfaces and that sealing occurs when the material displaces to conform to and fill the space between the mating surfaces. In some embodiments, the seal member 12a may be formed as a continuous core of conformable material. In the embodiments shown in
The tab member 14a may extend or project outward substantially away from the seal member outer perimeter to an edge of the one or more sealed components (e.g., first and second structures 16, 18) such that the tab member 14a may be visible when the components are sealed. Thus, the tab member 14a may be configured to provide a visual indication of an alteration in a physical characteristic of the seal upon exposure of the seal to at least one of an unacceptably high temperature or pressure when the seal is in use without separating the sealed components. Referring to
With continued reference to
To provide a visual indication of instances when the seal device 10a is exposed to a higher than acceptable temperature and pressure (based on normal thresholds for the seal device 10a), the material used to form the seal device 10a may include a mixture of a conformable seal compound and a characteristic changing material. A known seal compound used for forming the seal device 10a, or any of the components forming the seal device 10a (e.g., seal member 12a, tab member 14a) may include a variety of seal forming materials. For instance, the seal compound or material used to form the seal device 10a may be an elastomeric or polymer based material, cellulose, thermoset rubber, acrylic, composite, polyacrylic, or other flexible sealing material of known art.
The characteristic changing material may be a reactive substance that is mixed with the seal compound for forming the seal device 10a. The reactive substance can be reactive particulates, dyes, liquids and/or powders that are mixed with a seal compound for forming the seal device 10a that change in appearance when certain thresholds are exceeded. Thus, using the characteristic changing material, detecting an undesirable change in seal pressure or temperature may then be made possible by visually detecting a change in a physical characteristic of the seal device 10a (or at least the tab member 14a of the seal device 10a) when the seal device 10a has been exposed to a mechanical stress or temperature above a threshold intensity (shown as seal device 10b and corresponding components seal member 12b and tab member 14b in
The seal device 10a may be designed to have a threshold intensity that is no greater than the minimum intensity that would cause the seal device to be rejected as defective or possibly defective due to excessive experienced stress or an excessive increase in temperature. Then, if the seal device so designed is subjected to such excessive stress or temperature and exhibits a change of appearance, this change of appearance indicates that it has experienced a stress or temperature exceeding its threshold intensity. The seal device 10b can be replaced based on detection of the change of appearance. For example, in instances when the strain on the seal device 10a exceeds a max pressure (e.g., sixty three percent for PIP seals, sixty-nine percent for O-ring type seals, or eighty percent for H-type seals), or a max temperature, the seal device 10a and/or the tab member 14a alone may change in appearance. Thus, the characteristic changing material and tab member 14a are configured to provide a visual indication of seal integrity by providing a change in a seal characteristic that may be visible without separating sealed components, as shown in
In some embodiments, the reactive substance may be a thermochromic, piezochromic, or chemichromic compound or dye. In other instances, the reactive substance can include small particles of any pressure sensitive, thermally or chemically reactive material, including, but not limited to, reactive ions, oxidants, acidic materials, caustic materials.
In exemplary embodiments, at least a portion of the characteristic changing material is a thermochromic material. Thermochromic material may be configured to change the one or more frequencies of light which it principally absorbs in response to one or more temperature changes. In some embodiments, the thermochromic dye is a pH-indicator dye or a leuco dye. Thus, thermochromic material can be used to indicate whether the seal device 10a has been exposed to a particular temperature. In any embodiment, the thermochromic material or compound may include one or more of thermochromic pigments or dyes that exhibit a change in absorption spectrum through changes in the pressure applied to them. Thus, at least a portion of the seal device 10a may change its appearance by developing or changing color after exposure to a mechanical stress exceeding a threshold intensity. Accordingly, the color of at least a portion of the thermochromic material (and thus, the seal device 10a or at least a portion of the seal device 10a) may be a color other than a usual seal color after at least a portion of the seal is exposed to the mechanical stress exceeding the threshold intensity (e.g., seal device 10b including seal member 12b and tab member 14b shown as having horizontal stripes in
The color change can be a permanent shift in the one or more frequencies absorbed or a reversible shift that slowly or quickly reverts back to absorbing appropriate frequencies for the initial temperature. The type of thermochromic material mixed with the seal material may be based on the process for verification of seal quality. Thus, a one embodiment includes a permanent or irreversible thermochromic material. An irreversible thermochromic material may be configured to retain the coloration change upon exposure to excess temperatures, which may be generally an indication of the highest temperature reached by the seal material during the seal operation. In this manner, permanent thermochromic material may provide a mechanism for replacing the seal device 10b after detection of the seal device 10b having been exposed to a higher than acceptable temperature. Other embodiments may include a reversible thermochromic material. A reversible thermochromic material may be configured to reverse the changed characteristic (e.g., color change) when the stress to the seal has ceased. This would allow for a visual inspection of a change in characteristic while the seal is in place and in use during operation (e.g., while an engine is running), but also allow for the characteristic change to reverse when not in operation (e.g., when the engine is off and cool again). In some embodiments, the thermochromic compound is a UV thermochromic ink
In further exemplary embodiments, at least a portion of the characteristic changing material is a piezochromic material. Piezochromic materials are compounds or dyes which, upon exposure to different compressive or tensile forces, alter or shift the frequencies of light which they absorb. Thus, piezochromic material would desirably be included in the seal device 10a in applications where the seal device 10a was in compressive or tensile stress. In preferred embodiments, the piezochromic material may be configured to change its appearance when the seal device 10a is exposed to mechanical stress exceeding a threshold intensity. Using the tab member 14a, the seal device 10a may be inspected from the exterior for a change in the appearance of at least some of its piezochromic material that is characteristic of exposure of the seal to mechanical stress exceeding a threshold intensity or stress level. For instance, where the seal device 10a material includes piezochromic material, at least a portion of the seal device 10a may not be activated before at least a portion of the seal is exposed to mechanical stress exceeding the threshold intensity.
In any embodiment, the piezochromic material or compound may include one or more of piezochromic pigments or dyes that exhibit a change in absorption spectrum through changes in the pressure applied to them. Thus, at least a portion of the seal device 10a may change its appearance by developing or changing color after exposure to a mechanical stress exceeding a threshold intensity. Accordingly, the color of at least a portion of the piezochromic material (and thus, the seal device 10a or at least a portion of the seal device 10a) may be a color other than a usual seal color after at least a portion of the seal is exposed to the mechanical stress exceeding the threshold intensity. For instance, the color of at least a portion of the seal device 10b may be blue after at least a portion of the seal is exposed to the mechanical stress exceeding the threshold intensity. In other embodiments, the color of at least a portion of the seal device 10b may be green after at least a portion of the seal is exposed to the mechanical stress exceeding the threshold intensity. In some embodiments, the change of appearance may be detectable by the eye of a human observer. In some embodiments, the change of appearance may be detectable by the unaided eye of a human observer. In some embodiments, the threshold intensity is lower than the intensity necessary to damage the seal. In all embodiments, inspecting the seal device 10a may be carried out at least partially using visual inspection to determine the change in the appearance of at least some of its piezochromic material.
In some embodiments, the piezochromic material may be irreversible. Irreversible piezochromic material may be adapted so that when the seal device 10a is strained but then returns to its original dimensions, the piezochromic material may be irreversibly changed or at least changed in a way that may be detectable for a period of time after it occurs. Other embodiments may include a reversible piezochromic material. A reversible piezochromic material may be configured to reverse the changed characteristic (e.g., color change) when the stress to the seal has ceased. This would allow for a visual inspection of a change in characteristic while the seal is in place and in use during operation (e.g., while an engine is running), but also allow for the characteristic change to reverse when not in operation (e.g., when the engine is off and cool again). In further embodiments, chemical compounds known as sensitizers could optionally be added to the compounds to change or adjust the amount of stress required to trigger absorption of different light frequencies or cause a color change.
The seal compound containing the characteristic changing material may be processed by a variety of well-known processing techniques. These include extrusion, injection molding, transfer molding, compression molding, solution casting and variations thereof. For instance, the seal compound and the characteristic changing material may be placed in the hopper of a laboratory model injection molding machine for mixing. In all instances, the pressure sensitive, thermally or chemically reactive particulates, dyes, powders or other such mixable substances may be mixed with the seal forming compound such that a uniform or substantially uniform distribution of characteristic changing material may be achieved throughout the entirety of the seal device 10a. The characteristic changing material may alternatively be adsorbed onto or absorbed into seal compounds.
A seal device 10a as described herein is configured to provide a visual indication of seal integrity. Specifically, the seal device 10a includes a combination of a characteristic changing material mixed with a standard seal compound used to form a seal member 12a and an outward extending seal tab member 14a. The combination of the characteristic changing material and the tab member provide a visual indication that a temperature or pressure limit of the seal has been exceeded without separating the sealed components. Specifically, the seal device 10a in its entirety or the exposed tab member 14a alone may be configured to change colors when the seal is subjected to a temperature or pressure that exceeds a threshold temperature or pressure for the seal device 10a.
The type of early seal failure detection capability described herein has the potential to provide significant savings, reduce repair costs, and prevent productivity losses due to damaged engines. Specifically, a seal can be repaired upon detection that the seal has been compromised and/or before the contained fluid escapes and causes significant damage to the sealed components or machine in high pressure and/or high temperature applications. Such applications include, but are not limited to, hydraulic pumps, motors, actuators, connectors and the like.
It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed seal device. Other embodiments will be apparent to those skilled in the art from consideration of the specification and practice of the disclosed seal device. It is intended that the specification and examples be considered as exemplary only, with a true scope being indicated by the following claims and their equivalents.
