Patent Publication Number: US-6655499-B2

Title: Washer and tamper-evident cap for oil plug

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention is directed to a device to prevent oil from “inadvertently” draining from the oil pan. More particularly, the present invention is directed to a combined sealing washer and a tamper evident cap for enclosing the drain plug. 
     Following an oil change, a vehicle&#39;s drain plug will occasionally not be fully seated and will vibrate loose, resulting in the oil draining out of the crank case (or oil pan) and the engine overheating, seizing or otherwise being severely damaged. A recent scam being employed by some unscrupulous persons is to take a “clunker” to a local outlet of a nationwide chain of service centers, having the oil changed, intentionally backing the plug out a few rotations, knowing that after a few hundred miles, the plug will work its way out of threaded engagement in the oil pan. The oil “inadvertently” drains out, resulting in a blown engine that is then replaced by the nationwide chain to avoid the bad publicity of a dissatisfied customer. This results in a significant cost to the service center which necessarily is passed on to the consumer in the form of increased costs of service. 
     The present invention is designed to keep the oil plug in threaded engagement with the oil pan and to prevent anyone from backing the plug out to perpetrate such a fraud on a service center. The sealing device is comprised of a elastomeric washer that seats under the head of the bolt serving as the oil plug; a cylindrical sleeve extending up from the washer and integral therewith, the cylindrical sleeve having securement means adjacent an upper edge thereof, a tamper-resistant, tamper-evident cap attachable to the cylindrical sleeve by said securement means, the cap surrounding the head portion of the oil plug preventing access thereto, attempted removal of the cap resulting in damage to said apparatus which makes such an attempt apparent; whereby the sealing device prevents loosening of the oil plug until it is intentionally removed. The device further comprises a membrane extending between the washer and the cap whereby said apparatus forms a single integral unit. The integral unit is preferably made of a single elastomeric material such as polypropylene. The device includes a thin-walled region of at least one of the cylindrical wall and the cap whereby attempted removal of the apparatus will result in the apparatus being rendered unusable. It will be impossible to loosen the bolt and reengage the cap to make it appear as if the installer was at fault. Further, the device is sized such that when the cap is secure, even were the oil plug to loosen, it would nonetheless remain in threaded engagement with the oil pan. In on embodiment, even if the cap is pried off, the washer will remain in sealing engagement beneath the bolt head maintaining the oil plug fully seated until it is intentionally removed to permit the oil to be drained. In a second embodiment, the prying off of the cap results in the cap being torn so that the oil cap cannot be reengaged. This prevents the oil plug from being tampered with and the cap reinstalled to make it appear that an error was made by the professional at the service center. In addition, these weakened areas of the cylindrical wall and the cap facilitate removal prior to a subsequent oil change. 
     Various other features, advantages and characteristics of the present invention will become apparent after a reading of the following specification. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The preferred embodiment(s) of the present invention are set forth in the drawings, like items bearing like reference numerals and in which 
     FIG. 1 is a cross-sectional side view of a first embodiment of the tamper-evident cap of the present invention; 
     FIG. 2A is an inverted side view of the first embodiment shown installed with parts broken away for clarity; 
     FIG. 2B is top view showing the washer secured beneath the oil plug after tampering; 
     FIG. 3 is a top view of the sealing cap of a second embodiment of the tamper-evident cap of the present invention; and 
     FIG. 4 is a front view of the sealing cap of the second embodiment of the tamper-evident cap of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     A first embodiment of the sealing device for an oil plug  11  is shown in FIGS. 1 and 2A generally at  20 . Sealing device  20  includes elastomeric washer  22  which is seated under the head  13  of oil plug  11  against the oil pan (not shown). Elastomeric washer  22  will be compressed when bolt  11  is properly seated such that it will inhibit loosening of the bolt  11  as any conventional washer would. 
     A partially closed-ended cylindrical sleeve  24  surrounds washer  22 , extends upwardly there from and is formed integrally therewith, with the washer  22  and partially closed end of sleeve  24  defining floor  23 . Securement means is formed as a protruding lip  26  around the upper periphery of sleeve  24 . Cap  28  has a inwardly extending abutment  30  which engages over lip  26  to secure the cap  28  to the cylindrical sleeve and an outwardly extending flange  32 . Cap  28  is designed to be tamper-resistant and tamper-evident such that any effort to remove cap  28  will result in the sealing device  20  becoming detached and rendered incapable of reuse. 
     In the first embodiment (FIGS. 1,  2 A and  2 B), this is accomplished by weakening a portion of the floor  23  between washer  22  and cylindrical sleeve  24 . In use, bolt  11  is secured through opening  34  in washer  22  into the oil pan (not shown). Abutment  30  of cap  28  is flexed outwardly over lip  26  by bending interconnecting membrane  36  into a U-shape (FIG.  2 A). Once abutment  30  is engaged under lip  26 , the tamper-evident cap  20  may not be reopened until it is time to remove it. When removal of sealing device  20  is desired, a screw driver, or the like, is used to pry upwardly on outwardly extending flange  32 . This will cause weakened portion of floor  23  to break away leaving washer  22  seated under bolt head  13  until oil plug  11  is removed. As will be apparent, even should someone attempt to prematurely remove sealing device  20 , washer  22  will retain oil plug  11  secured in the oil pan (FIG. 2B) until it is intentionally removed eliminating the problem of the oil plug  11  vibrating out of the oil pan. 
     A second embodiment of the sealing device of the present invention is shown in FIGS. 3 and 4 generally at  20 ′. In this embodiment, two portions of cap  28 ′ on either side of flange  32 ′ are weakened as by thinning the wall, as at  38 ′. Since regions  38 ′ are thinned, when a screw driver is used to pry upwardly on flange  32 ′, cap  28 ′ will tear at these points. This facilitates removal of sealing device  20 ′ for a subsequent oil change and makes evident any attempt to open cap  28 ′ to tamper with bolt  11 . In addition, washer  22  remains engaged beneath bolt head  13  avoiding loosening of the oil plug  11 . 
     The present invention provides a sealing device  20 ,  20 ′ which secures a oil plug  11  against inadvertent loosening by provision of a elastomeric washer  22  beneath the bolt head  13 . A cylindrical sleeve  24  surrounds the bolt head  13  and, once abutment  32 ,  32 ′ on cap  28 ,  28 ′ is engaged beneath lip  26  atop sleeve  24 , bolt  11  is secured from tampering. Any attempt to gain access to bolt  11  will be made evident either by the tearing of the weakened area of floor  23  or by the tearing of weakened areas  38 ′. Sealing device  20 ,  20 ′ will significantly reduce or eliminate the costly repairs associated with “inadvertent” loss of lubricating oil from the engine resulting from oil plug  11  vibrating loose. 
     Various changes, alternatives and modifications will become apparent to one of ordinary skill in the art after a reading of the foregoing specification. It is intended that all such changes, alternatives and modifications as fall within the scope of the appended claims be considered part of the present invention.