Patent Publication Number: US-2010127460-A1

Title: Seals with integrated leak detection capability

Description:
BACKGROUND OF THE INVENTION 
     The present invention pertains to a multifunctional gasket or seal that provides integrated leak detection functionality. Some examples of use include seals in containment and transfer systems having hazardous or environmentally damaging fluids, seals for mechanical devices having refrigerant, coolant, lubricating or fuel fluids, and seals for structure that provides separation of dissimilar material phase, environmental, or energy state. 
     Known fluid seals are made of a variety of materials and have a multitude of design configurations that include, but are not limited to, (i) a circular conformable elastomeric O-ring seated in a channel (gland) of a metallic or plastic fitting, (ii) circular washer made of soft conformable metallic or plastic material, (iii) flat gasket of various flat pattern made with conformable fibrous, cellulous, particulate, or polymeric material, (iv) circular compression fittings with off-set tapered mating surfaces, (v) circular flared fittings with conformable flared tubings, and (vi) circular threaded pipe fittings with off-set tapers, etc. 
     It is known that sealing using conformable materials is 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. 
     It is also known that sealing of relatively rigid mating surfaces is achieved when such surfaces are in full or partial and often tight contact. Examples of such sealing are compression fittings and threaded pipe fittings that often have tapered mating surfaces that are offset to create tight contact during rotational tightening. 
     Presently, leak detection is achieved using a multitude of devices that are external and separate from the fluid containment structure and seal. Such devices include, but may not be limited to: (i) stationary chemical detection alarms, (ii) handheld portable chemical detection sensors, and (iii) handheld portable sonic emission detectors. Other means for leak detection include the use of foaming agents (soap) and dye that provide visual identification of a leak. 
     It is also known that leaks may be identified through the use of pressure sensors that measure fluid pressure within the containment system. Such systems typically measure bulk fluid pressure using a single pressure sensing device. Other means for direct indication of a leak include the use of temperature sensors that measure fluid temperature within the containment system. Such systems typically measure localized temperature at a specific location within the system using a single temperature sensing device. Fluid leakage can be identified by a corresponding increase in temperature readings. 
     Typical leak detection methods and devices identify leaks after leakage has occurred outside the fluid containment structure. One new type of seal that provides leak detection and leak progression detection before leakage has occurred outside of the fluid containing structure is disclosed in U.S. Pat. No. 7,316,154 B1 to Benneft, which is incorporated in its entirety herein by reference. 
     Bennett discloses multifunctional seals including sensors and sensor circuitry between each seal. The seals also include a power source and may include embedded electronics within a central core region. Seals are constructed to detect fluid leak progression using redundant sealing and sensors located between each set of seals to allow for the detection of leak propagation prior to leakage outside the sealed containment or transfer structure. Seal members are disclosed and the seals may include a pliable sealing material mounted to the seal member. 
     BRIEF SUMMARY OF THE INVENTION 
     In one embodiment of the invention, a seal device is provided with integrated leak detection capability for detecting the initiation of a leak of a contained fluid and includes a seal member having at least one sealing contact surface and a sensing member located on the sealing contact surface, the sensing member detecting if a breach has occurred in a seal formed between the sealing contact surface and a member against which the sealing contact surface is sealed to provide an indication of the breach before a complete breach of the seal occurs; and a deposit of sense enabling material on the seal member located between the contained fluid and the sensing member. 
     The sense enabling material can be: a material that alters the electrical performance or property of a sensing member; or a material that alters the performance or property of the contained fluid to allow it to be detected; or a material connected to the sensing circuit whose electrical property is changed by the contained fluid. 
     The seal member can be a header or other gasket, the sense enabling material can be reactive particulates that are mixed with a binder material for deposition on the seal member, and the binder material may break down upon contact with the contained fluid. In one embodiment, the contained fluid carries the electrically conductive particulate solution into contact with the sensing member to detect the initiation of a leak of the seal as made possible by detecting the resulting change in conductivity in the sensing member or the change in conductivity in the space or separating material located between at least two electrical conductors. 
     The seal member can be a header or other gasket, the sense enabling material can be reactive particulates that are mixed with a binder material for deposition on the seal member, and the binder material may break down upon contact with the contained fluid. In one embodiment, the contained fluid carries the reactive particulate solution into contact with the sensing member or an electrical conductor to detect the initiation of a leak of the seal as made possible by detecting the resulting change in conductivity in the sensing member or the change in conductivity in the space or separating material located between at least two electrical conductors, or the change in conductivity of at least on electrical conductor that occurs due to corrosion or material alteration resulting from being in contact with the reactive particles within the sense enabling material. 
     In another embodiment, the binder material is removed, while leaving the conductive or reactive particulates, prior to installation of the seal member. 
     In yet another embodiment, the conductive or reactive particulates are mixed with a fluid media prior to deposition on the seal member. The fluid media can be evaporated from the seal member prior to installation. 
     The sensing member may include at least two concentric or closely spaced electric conductors, and the conductive particulates within the sense enabling material may cause a short circuit or closed switch between the electric conductors when carried by the contained fluid. The conductive particulates may be placed in close proximity to the electric conductors upstream in the direction of fluid flow, or the conductive particulates may be placed between the electric conductors. 
     In another embodiment of the invention, a method of obtaining a seal with integrated leak detection capability for detecting the initiation of a leak of a contained fluid is provided that includes the steps of providing a fluid carrying member for containing the fluid and a sealing contact face on the fluid carrying member configured to form a seal with another member; providing a seal member, including a contact face configured to seal against the contact face of the fluid carrying member, and a sensing member located on the contact face of the seal member; providing a deposit of sense enabling material on the contact face of the seal member; forming a seal between the sealing contact surfaces of the seal member and the contact face of the fluid carrying member, wherein when the seal is intact, the sensing member and the deposit of sense enabling material are not in contact with the contained fluid in the fluid carrying member; and sensing the initiation of a leak of the seal by the contained fluid carrying the sense enabling material into contact with the sensing member. 
     The sense enabling material can include conductive or reactive particulates/mixture. The method of obtaining a seal with integrated leak detection capability may also include the steps of providing a binder and mixing the binder with the conductive or reactive particulates for deposition on the seal member. The binder material may break down upon contact with the contained fluid. The conductive or reactive particulates may be carried by the contained fluid to contact the sensing member to detect the initiation of leak of the seal. 
     The method of providing a seal with integrated leak detection capability may also include the steps of providing a fluid media and mixing the fluid media with the conductive or reactive particulates prior to deposition on the seal member. The fluid media may be evaporated from the seal member prior to installation. 
     The sensing member may include at least two concentric or adjacent electric conductors, wherein the conductive particulates may cause a short or closed circuit between the concentric or adjacent electric conductors when carried by the contained fluid. 
     The sensing member may include at least one electric conductor or sensing member, wherein the sense enabling material may cause a change in electrical performance or property of the electric conductor or sensing member as can be caused through corrosion or material alteration of the electric conductor or sensing member when reactive particulates are carried by the contained fluid into contact with the electric conductor or sensing member. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and objects of this invention and the manner of obtaining them will become more apparent and the invention itself will be better understood by reference to the following description of embodiments of the present invention taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a perspective view of one embodiment of a seal device having integrated leak detection capability in accordance with the subject invention; 
         FIG. 1A  is a cross sectional view of the seal device of  FIG. 1  taken along line  1 A- 1 A; 
         FIG. 2  is a perspective view of an alternate embodiment seal device; 
         FIG. 2A  is an enlarged view of the area indicated in  FIG. 2 ; and 
         FIG. 3  is a plan view of a cylinder block for which the seal device of  FIG. 2  may be used in conjunction to form a seal. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present invention. The exemplification set out herein illustrates embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION 
     For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings, which are described below. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. The invention includes any alterations and further modifications in the illustrated devices and described methods and further applications of the principles of the invention, which would normally occur to one skilled in the art to which the invention relates. 
     Referring now to  FIGS. 1 and 2 , one embodiment of a seal device, in accordance with the subject invention, is generally indicated as  10 . Seal device  10  includes a seal member, generally indicated as  12 ; a sensing member, generally indicated as  14 ; and a deposit of electrically conductive or chemically reactive particulates, solution, and/or mixture, generally indicated as  16 , and reference to particulates in this application shall include any form of conductive or chemically reactive material. 
     In the embodiment shown, seal member  12  is a member having the configuration of a head gasket made of elastomeric, cellulose, metallic, or other sealing material of known art. It should be appreciated, however, that seal member  12  may take on any desirable sealing configuration, including O-rings, washers, grommets, other gaskets, or fittings. Seal member  12  may be made from a single piece flexible member or may include a laminated design consisting of a compliant seal mounted on a more rigid backing plate or member. It should also be appreciated, for purposes more fully set forth below, that seal member  12  has a dielectric contact surface or includes a dielectric coating in the area of sensing member  14 . 
     Seal member  12  also includes a sealing contact face  20 , a plurality of openings  22 , corresponding with cylinder bores for holding a contained fluid and a plurality of mounting flanges  24   a - e,  including bolt openings  26   a - e,  respectively, for mounting the head gasket  12  between a cylinder head (not shown) and cylinder block. 
     In the embodiment shown, sensing member  14  includes two concentric electric conductors  30  and  32 , which are located on sealing contact face  20  and electrically separated from one another. It should be appreciated that electric conductors  30  and  32  may be applied with any known method including, but not limited to, using electrically conductive foils, printed conductive inks or compounds, or vapor metal deposition. Furthermore, device  12  includes a pair of electrical leads  34  and  36  to provide an electric current to electric conductors  30  and  32 , respectively. It should be appreciated that an insulator, insulative coating, or other means to prevent electric contact must be provided where electric lead  36  crosses electric conductor  30 . 
     Electrically conductive or chemically reactive particulates  16  are deposited on contact face  20  and concentric with electric conductors  30  and  32 . Conductive or reactive particulates  16  are located between electric conductors  30 ,  32  and cylinder openings  22 . The conductive particulates can include small particles of any electrically conductive material, such as copper, aluminum, silver, gold, carbon, or carbon nano materials. The reactive particulates can include small particles of any chemically reactive material, including, but not limited to, reactive ions, oxidants, acidic materials, caustic materials. The conductive or chemically reactive materials can be mixed with a binder for depositing the particles onto seal member  12 . The binder may be made from a material that is soluble in the contained fluid, for reasons set forth below, or alternately, the binder may be removed after depositing the particulates. and print a conductive or reactive ink onto seal member  12 . The fluid media can then be evaporated away prior to installation of the seal member. 
     Referring now to  FIG. 2 , an alternate embodiment seal device is generally indicated as  110 . Seal device  110  is similar in most respects to seal device  10 . However, seal device  10  includes a seal member  112  with a slightly different configuration. In addition, seal device  110  includes an outer electric conductor  30 A which is split about electric lead  36 , as best shown in  FIG. 2A . In addition, seal device  110  includes a pair of electric leads  34   a  and  34   b  connected to the ends of conductor  30   a  on either side of lead  36 . 
     Referring now to  FIG. 3 , a cylinder block is shown, generally indicated as  210 . Cylinder block  210  includes a sealing contact face  220  and cylinder bores  222 . Cylinder block  210  also includes numerous openings  240 ,  242 ,  246 , and  248 , for example, which may be used for bolt attachment or cooling purposes. In a normal engine operation, as is known, cylinder block  210  is mated with a cylinder head (not shown) and bolted together with a seal member, such as  12  or  112 , to provide a seal therebetween. 
     In normal operation and as installed, sealing contact face  20  of seal member  12 / 112  will form a fluid seal with sealing contact face  220  on cylinder block  210  or a sealing contact face (not shown) on the cylinder head. In normal operation, when a seal is functioning properly, electrically conductive or chemically reactive particulates  16  will be dry and not exposed to the fluid contained in the cylinder block. However, if a leak is initiated, and fluid starts escaping between sealing contact face  20  of seal member  12 / 112  and sealing contact face  220 , the fluid will contact the particulates and carry the particulates to sensing member  14 . If conductive particulates are used, as the conductive particulates fill the gap between electric conductors  30  and  32 , a short circuit or switching of the circuit will be created so that an alarm or other leak indicator may be activated to provide a notification that a leak has initiated. If reactive particulates are used, as the reactive particulates come into contact with electric conductors  30  and  32 , a corrosion or modification of the electric conductors will occur causing a change in the electrical properties or performance of the conductor to change so that an alarm or other leak indicator may be activated to provide a notification that a leak has initiated. 
     This type of early leak detection capability has the potential to provide significant savings, reduce repair costs, and prevent productivity losses due to damaged engines, as the leak can be repaired before the contained fluid escapes and causes significant damage to the engine. 
     While the invention has been taught with specific reference to these embodiments, one skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the invention. The described embodiments are to be considered, therefore, in all respects only as illustrative and not restrictive. As such, the scope of the invention is indicated by the following claims rather than by the description.