Abstract:
A hydraulic cylinder contamination prevention system for preventing large and small contaminants from entering into a hydraulic cylinder, including a hydraulic cylinder rod cover for underwater use with at least one automatic valve for preventing water circulation between the outside environment and the enclosed environment of the cylinder rod cover when the cylinder is stationary, egress of water from the cylinder rod cover when the cylinder is retracted, and ingress of water into the cylinder rod cover when cylinder is extended, and an external and abrasive cylinder rod scrubber.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 12/356,932 filed on Jan. 21, 2009 and claims priority to Provisional Patent Application No. 61/021,748 filed on Jan. 17, 2008. 
    
    
     FIELD OF INVENTION 
     The invention generally relates to an apparatus and method for preventing contamination from entering a hydraulic cylinder in an underwater environment. 
     BACKGROUND OF INVENTION 
     The use of hydraulic cylinders for lifting heavy loads is well known. A common problem in the use of hydraulic cylinders in dirty or underwater environments is contaminants entering into the hydraulic system and causing problems with the hydraulic pumps. Contaminants such as mud, dirt, marine growth, and mineral deposits build up on the cylinder rod and are dragged through the seals of the cylinder barrel. One of the most challenging contaminants are mineral deposits because they are microscopic particles diluted into water. As water flows around the cylinder rod minerals such as calcium carbonate attach to the cylinder rod. 
     There are many solutions for protecting a hydraulic cylinder shaft in above water applications, but most will not work in an underwater application for various reasons that will be described. The most common cylinder rod protection is a boot that prevents contaminants from contacting the rod of a cylinder. These can be seen in use on motorcycle shock absorbers, heavy machinery and more. The main problem with using a standard boot on an underwater cylinder is the change in volume inside the cylinder boot when the cylinder expands and contracts. Standard cylinder boots allow air to free flow in and out of the boot such as in U.S. Pat. No.6,932,356 to Gloaguen. If the standard cylinder boot is used underwater the boot will implode while the cylinder extends because the cylinder boot cannot suck in water at same rate it can suck air in. When the cylinder retracts the cylinder boot will balloon because the cylinder boot cannot push water out as fast as it can push air out. A simple solution to allowing water to flow in and out of the cylinder boot would be to add a large vent hole. The cylinder boot with a large vent hole would work to keep large contaminants off of the cylinder rod, but because the hole in the cylinder boot allows water to free flow in and out of the cylinder boot unlimited minerals can float into the cylinder boot and attach to the cylinder rod still leaving a contamination problem. 
     Another common device used to prevent contamination entering into a hydraulic cylinder is an internal cylinder scrapper. U.S. Pat. No.4,577,363 to Wyse, U.S. Pat. No. 4,461,486 to Tregonning and U.S. Pat. No. 6,047,970 to Friend are examples of cylinder scrapers. Internal cylinder scrappers are knife edged rings, made from stainless steel or bronze, that are fixed into a cylinder head above the cylinder seals. Internal cylinder scrappers do a good job of removing large marine growth like barnacles, but they allow small particles like mineral deposits or marine growth residue to pass through into the cylinder. 
     Accordingly, there is a need in the art for a cylinder contamination protection system suitable for underwater use that protects a cylinder from one or both of large contaminants such as mud, dirt and marine growth, and small contaminants such as mineral deposits and marine growth residues. 
     SUMMARY OF THE INVENTION 
     The disclosed embodiments of the present invention include a hydraulic cylinder contamination prevention system that prevents one or both of large and small contaminants from entering into the hydraulic cylinder. The hydraulic cylinder contamination prevention system may include a hydraulic cylinder rod cover for underwater use with at least one automatic valve for preventing water circulation between the outside environment and the enclosed environment of the cylinder rod cover when the cylinder is stationary, egress of water from the cylinder rod cover when the cylinder is retracted, and ingress of water into the cylinder rod cover when cylinder is extended. The hydraulic cylinder contamination prevention system may include an external and abrasive cylinder rod scrubber. 
     The cylinder boot with at least one automatic valve serves two purposes; it protects the cylinder rod from large contaminant build up like mud, barnacles, muscles, and other marine growth and it eliminates the free flow of mineral filled water around the cylinder rod, thus greatly reducing and possibly eliminating the mineral build up on the cylinder rod. The preferred embodiment of the automatic valve of the cylinder rod cover is a rubber flapper valve with a diameter of at least ⅜ inch. The rubber flapper valve seals on itself while the cylinder is stationary. When the cylinder is retracted or extended the force of the water entering in or exhausting from the cylinder rod cover pushes open the flapper valve. The open flapper valve allows water to flow in and out of the cylinder rod cover without causing implosion or ballooning of the cylinder rod cover when the cylinder is extending or retracting. The automatic valve may also be a slit in the flexible material of the hydraulic cylinder rod cover such as a slit in a rubber cylinder boot. 
     The preferred embodiment of the cylinder rod cover is a corrugated shape similar to a bellows. The number and size of the corrugations is selected to allow marine growth on the cylinder rod cover while not inhibiting the expansion and contraction of the corrugated cylinder rod cover. The cylinder rod cover is preferably be made of a durable material such as EPDM rubber so the marine growth does not cause tearing. The durometer of the material is also to be considered since too soft durometer material will allow ballooning of the cylinder rod cover and too hard a durometer material will cause the cylinder rod cover to buckle. Through testing a preferred durometer is around Shore 80A. 
     If some small contaminants are able to attach to the cylinder rod the external and abrasive cylinder rod scrubber removes the remaining contaminants from the cylinder rod. The preferred embodiment of the cylinder rod scrubber is cut out of an abrasive scotch-brite type pad and then wrapped around the cylinder rod and clamped to the cylinder barrel. The cylinder rod slides through the abrasive cylinder rod scrubber removing any small contaminant build up. 
     Preferably, the cylinder rod cover and cylinder rod scrubber will be used together, but in some cases the cylinder rod cover and cylinder rod scrubber can be used separate of each other and perform their singular functions. An example of this would be a location with high marine growth, but low mineral content in the water (such as in salt water); in this case someone may choose to use just the cylinder rod cover. Another example would be a low marine growth low mineral content water location (such as in a fresh water lake); in this case someone may choose to use just the cylinder rod scrubber to keep the cylinder rod clean. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, which are schematic, and not to scale, wherein: 
         FIG. 1  is an isometric view of a cylinder boot. 
         FIG. 2  is a transparent isometric view of the cylinder boot. 
         FIG. 3  is a side view of the cylinder boot. 
         FIG. 4  is an isometric view of the cylinder boot mounted to a cylinder. 
         FIG. 5  is an isometric view of a boat lift with an extend cylinder with a boot attached thereto. 
         FIG. 6  is an isometric view of the boat lift of  FIG. 5  with the cylinder retracted. 
         FIG. 7  is a side view of the cylinder boot with an abrasive ring. 
         FIG. 8  is an isometric view of a second embodiment of the cylinder boot. 
         FIG. 9  is a second embodiment of the abrasive ring. 
         FIG. 10  is a side view of a cylinder with the abrasive ring of  FIG. 9  shown attached to the cylinder. 
         FIG. 11  is a cross-sectional side view of the cylinder of  FIG. 10  with a cylinder boot and abrasive ring attached. 
         FIG. 12  is a cross-sectional side view of an alternative cylinder boot extending over a hydraulic fluid port of a cylinder. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following descriptions illustrate aspects of the invention, and identify certain preferred embodiments of these aspects. The descriptions are not intended to be exhaustive, but rather to inform and teach a person of skill in the art who will come to appreciate more fully other aspects, equivalents, and possibilities presented, and hence the scope of the invention is set forth in the claims, which alone limit its scope. 
     Several details of the preferred embodiments are set forth in the following description:  FIGS. 1 through 12  provide a thorough understanding of such embodiments. One skilled in the art will understand that the present invention may be practiced without several of the details described herein. In the following description of the embodiments, it is understood that the figures related to the various embodiments are not to be interpreted as conveying any specific or relative physical dimension, and that specific or relative dimensions related to the various embodiments, if stated, are not be considered limiting unless the claims state otherwise. 
       FIG. 1  shows an isometric view of a preferred embodiment of a cylinder boot  10  comprising of a flexible corrugated cylinder  11 . The cylinder boot  10  uses a cylinder barrel attachment  12  which may be a clamp or zip tie to hold it fast to a cylinder barrel  41  of a hydraulic cylinder  40  such as shown in  FIG. 4 . The cylinder boot  10  also includes cylinder rod attachment  13  which is a end portion of the cylinder boot which fits more tightly around a cylinder shaft or rod  42  such as shown in  FIG. 4  to hold the end portion fast to the cylinder rod so that the end portion of the cylinder boot attached to the cylinder rod moves with the cylinder rod as it extends from and retracts into the cylinder barrel  41 . In the illustrated embodiment, the cylinder rod attachment  13  includes a pin hole  16  that is sized and located to coincide with a pin hole in the cylinder rod to allow insertion of a pin (not shown) through the pin hole  16  and the pin hole of the cylinder rod and thereby attach the end of the cylinder rod  42  to the mechanism it moves. When the pin is inserted into the pin hole  16  and the pin hole in the cylinder rod, the end portion of the cylinder boot  10  is securely affixed to the cylinder rod  42  and held in place during operation of the hydraulic cylinder  40 . 
     The cylinder boot  10  also includes a duck bill vent  14  and flapper vent  15 . Duck bill vent  14  and flapper vent  15  of cylinder boot  10  allow water to flow in and out of cylinder boot  10  when it travels between extended position “A” (shown in  FIG. 5 ) and collapsed position “B” (shown in  FIG. 6 ). When cylinder boot  10  is stationary, duck bill vent  14  and flapper vent  15  keep water from free flowing through cylinder boot  10 . The cylinder boot  10  may be made of a rubber material. Alternative venting may include a slit in the flexible material of the cylinder boot  10 . Although a slit would allow some leakage since not a perfect seal, it would serve the same purpose and accomplishes the desired function. In the preferred embodiments passive acting valves are used so their action is automatic and require no external control or power to operate, and simply respond to the water pressure applied thereto during operation of the cylinder boot  10  and the water flow. 
       FIG. 2  is a transparent isometric view of the cylinder boot  10  further comprising interiorly positioned collapsing guides  21 . Collapsing guides  21  have holes  22  to allow water to flow through. 
       FIG. 3  is a side cross-sectional view of cylinder boot  10  showing collapsing guides  21  nesting in the corrugated flaps of flexible corrugated cylinder  11 . 
       FIG. 4  is an isometric view of cylinder  40  illustrating its cylinder barrel  41  and cylinder rod  42 , shown with cylinder boot  10  protecting cylinder rod  42 . As discussed above, cylinder boot  10  attaches to cylinder  40  at cylinder barrel  41  with cylinder barrel attachment  12  and at cylinder rod  42  with cylinder rod attachment  13 . Collapsing guides  21  of cylinder boot  10  slide over cylinder rod  42  to allow cylinder boot  10  to collapse evenly when cylinder  40  is drawn into the collapsed position “B” (see  FIG. 6 ). The cylinder barrel  41  of cylinder  40  includes two hydraulic fluid ports  43  and  44  to control fluid powered operation of the cylinder. In the embodiment of  FIG. 4 , the cylinder barrel attachment  12  is located longitudinally outward of the fluid port  43  at the end of the cylinder barrel  41  from which the cylinder rod  42  extends. 
       FIG. 5  is a partial isometric view of a boatlift  50  with cylinder  40  in the extended position “A” with the cylinder rod  42  extended, with the cylinder boot  10  protecting cylinder rod  42  from the marine environment. 
       FIG. 6  is a partial isometric view of boatlift  50  with cylinder  40  in the collapsed position “B” with the cylinder rod  42  retracted, again with the cylinder boot  10  protecting cylinder rod  42  from the marine environment. 
       FIG. 7  is a side cross-sectional view of cylinder boot  10  showing collapsing guides  21  nesting in the corrugated flaps of flexible corrugated cylinder  11 . The rear collapsing guide  21  has abrasive ring  71  attached which serves as a cylinder rod scrubber. Abrasive ring  71  fits tightly to cylinder rod  42  shown in  FIG. 4 , to clean off any contamination attached to the cylinder rod  42 . 
       FIG. 8  shows an isometric view of a second preferred embodiment of the cylinder boot  10  comprising of a flexible corrugated cylinder  11 , cylinder barrel attachment  12 , cylinder rod attachment  13 , pin hole  16 , and flapper vent  15 . Flapper vent  15  of cylinder boot  10  allows water to flow in and out of cylinder boot  10  when it travels between extended position “A” (shown in  FIG. 5 ) and collapsed position “B” (shown in  FIG. 6 ). When cylinder boot  10  of  FIG. 8  is stationary, duck bill vent  14  and flapper vent  15  keep water from free flowing through cylinder boot  10 . 
       FIG. 9  is a second embodiment showing an alternative abrasive ring  90 . The abrasive ring  90  is preferably manufactured from a flat stock material by cutting out the design illustrated in  FIG. 9  with a scrubbing head portion including a pair of opposite diagonal cuts  91  which mate together in opposing positions when wrapped around the cylinder rod  42  when installed on the cylinder rod, and a scrubbing surface  93  that engages the cylinder rod as it extends and retracts to clean the cylinder rod. The cylinder rod  42  slides through the abrasive ring  90  which scrubs and thereby removes any small contaminant build up. The abrasive ring  90  includes a pair of attachment legs  92  that when the installed abrasive ring is wrapped around the cylinder rod  42  are positioned on opposite sides of the cylinder barrel  41  as shown in  FIG. 10 . The legs  92  are spaced apart sufficiently to be positioned with the fluid port  43  projecting therebetween. The preferred embodiment of the abrasive ring  90  is cut out of an abrasive scotch-brite type pad and then wrapped around cylinder barrel  41  and cylinder rod  42 , and clamped to thereto as will be described below. 
       FIG. 10  is a side view of cylinder  40  with abrasive ring  90  of  FIG. 9  clamped to cylinder rod  42  with scrubbing surface  93  thereof extending around the cylinder rod and clamped thereto by zip ties  111  thereby holding the scrubbing surface in tight engagement with the cylinder rod. The legs  92  of the abrasive ring  90  are shown clamped to cylinder barrel  41  with a zip tie  112 . With this arrangement, the cylinder rod  42  can slide through scrubbing surface  93  to clean off mineral deposits such as calcium carbonate. 
       FIG. 11  is a side cross-sectional view of cylinder  40  of  FIG. 8  with cylinder boot  10  and abrasive ring  90  attached. 
       FIG. 12  is a side cross-sectional view of cylinder  40  of  FIG. 9  using an alternative cylinder boot  10  with an end portion that extends over the fluid port  43  of the cylinder barrel  41  which has a hole or cutout sized and positioned to permit the fluid port  43  to extend therethrough. In this embodiment the fluid port  43  retains the cylinder boot  10  attached to the cylinder barrel  41  with or without the use of the zip time  112 .