Abstract:
A mobile oil recycling system adapted for use with an oil-lubricated combustion engine. The inventive system includes an evaporation chamber for changing the pressure of the oil from a first pressure to a second pressure lower than the first pressure. Metering holes in a textured three-dimensional evaporation surface at the second pressure allow oil to spread over the three-dimensional surface area and evaporate contaminants from the oil. In a specific embodiment, the system further includes a filtering system for removing solid contaminants from the oil. A housing contains and supports the filtering system and the contaminant removal chamber, and directs the flow of oil through the recycling system. In a more specific embodiment the housing includes a base having an oil inlet for allowing pressurized oil to enter the oil recycling system and an oil outlet for allowing oil at atmospheric pressure to exit the recycling system. The three-dimensional evaporation surface has channels or grooves therein and is located in the liquid and gas contaminant removal chamber. A vent in the housing allows vaporized contaminants to escape from the chamber. The unique three-dimensional surface of the present invention obviates the need for an electric heater element, and eliminates wasted space and excess weight inherent in systems that have evaporation units stacked on filters.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates to oil recycling devices. Specifically, the present invention relates to devices for maintaining clean engine oil while an engine is operating. 
     2. Description of the Related Art 
     Oil is a lubricant in a variety of applications ranging from electric generators to printing presses to automobiles. Such applications require clean oil with minimal liquid, gas, and solid contaminants. 
     Typical engine oil contains a variety of solid, gas, and liquid contaminants. Engine oil is contaminated by gases from engine cylinder blow-by; by solids from engine component wear, and by liquids from coolant leeks and condensed blow-by gasses. Liquids combine with sulfur and other compounds from cylinder blow-by, creating corrosive acids, such as sulfuric acid. These contaminants corrode engine parts and deplete special minerals and detergents added to help maintain important oil properties including lubricity and viscosity. 
     To reduce problems associated with oil contamination, full-flow filters were developed. All oil circulating around an engine equipped with a full flow filter is directed through the filter or filter housing. High flow requirements limit the ability of conventional full flow filters to remove very small solid contaminants. Large particles of twenty microns or larger often pass through such filters and contribute to engine wear. In addition, conventional full flow filters are ineffective at removing liquid contaminants from the oil. 
     To remove both solid and liquid contaminants from engine oil, mobile, i.e., onboard oil refining systems were developed. The systems continually remove, clean, and replace small amounts of oil from the engine as the engine operates. The systems include a special evaporation compartment that attaches to a by-pass filter. The evaporation compartment removes both gas and liquid contaminants from the oil, and the filter removes solid contaminants as small as one micron in diameter. Such small particles are often smaller than engine tolerances and do not contribute to engine wear. These oil refining systems may obviate the need for interval oil changes but require interval filter changes. 
     The systems require a large evaporation compartment and an expensive electric heating element. The heating element increases the risk of the systems exploding due to gas ignition. To reduce explosion danger, the evaporation compartments are constructed of strong, thick, and heavy metal. Also, the heating element eliminates a beneficial oil cooling effect that would otherwise occur. 
     The large size of the systems limits installation to large trucks and automobiles with ample space. Installation on most modern automobiles is difficult and expensive due to limited space. In addition, electrical connections required for the electric heating elements complicate installation, and decrease the reliability of the systems. Public acceptance of the systems has been minimal as a result of these problems. 
     Hence, a need exists in the art for a safe, space-efficient and cost-effective mobile oil recycling system that removes both solid and liquid contaminants from oil. There is a further need for a system that may be easily installed on modern automobiles. 
     SUMMARY OF THE INVENTION 
     The need in the art is addressed by mobile oil recycling system of the present invention. In the illustrative embodiment, the inventive system is adapted for use with a combustion engine and includes an evaporation chamber for changing the pressure of the engine oil from a first pressure to a second pressure lower than the first pressure. Metering holes in a textured three-dimensional evaporation surface at the second pressure allow oil to spread over the three-dimensional surface area and evaporate contaminants from the oil. This evaporation process has a desirable oil cooling effect. 
     In a specific embodiment, the system includes a filtering system for removing solid contaminants from the oil. A housing contains and supports the filtering system and the evaporation chamber, and directs the flow of oil through the system. The housing includes a base having an oil inlet for allowing pressurized oil to enter the oil recycling system and an oil outlet for allowing oil at atmospheric pressure to exit the recycling system. An evaporation surface in the liquid and gas contaminant removal chamber facilitates the removal of gas and liquid contaminants from the oil. A vent in the housing allows vaporized contaminants to escape. 
     The housing includes a first wall and a second wall. The inside surface of the first wall is the evaporation surface and is textured for maximizing evaporation surface area. The filtering system includes a space between the first wall and the second wall. Oil enters the space via the oil inlet in the base of the housing. The filtering system includes a jet on the oil inlet for creating a centrifugal flow in the space that forces large particles out of circulation. 
     In the illustrative embodiment, the housing includes a spin-on filter canister. The filtering system includes a gradient density low-micron filter that removes solid contaminants and helps absorb and neutralize liquid contaminants. The filter is located between the space and the first wall. Strategically located holes in the first wall allow oil to pass through the filter and onto the evaporation surface. The first wall and the second wall are concentric tubular walls, capped at one end by the base of the housing, and at the other end by an end cap. 
     The novel design of the present invention is facilitated by grooves or channels in the evaporation surface that increase the rate of evaporation of contaminants from oil on the surface, thereby obviating the need for an electric heater element. This texturing of the surface to create a three-dimensional surface eliminates wasted space and excess weight inherent in systems that have evaporation units and heater elements stacked on filters. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a cross-sectional view of a conventional mobile oil recycling system. 
     FIG. 2 is cross-sectional view of a mobile oil recycling system constructed in accordance with the teachings of the present invention. 
     FIG. 3 is a cross-sectional view of the recycling system of the present invention including an evaporation heater. 
     FIG. 4 is a cross-sectional view of a first alternative embodiment of the present invention including a spin-on filter. 
     FIG. 5 is a cross-sectional view of an illustrative embodiment of the present invention. 
     FIG. 6 is a cross-sectional view of a second alternative embodiment of the present invention. 
     FIG. 7 is a cross-sectional view of a third alternative embodiment of the present invention. 
    
    
     DESCRIPTION OF THE INVENTION 
     While the present invention is described herein with reference to illustrative embodiments for particular applications, it should be understood that the invention is not limited thereto. Those having ordinary skill in the art and access to the teachings provided herein will recognize additional modifications, applications, and embodiments within the scope thereof and additional fields in which the present invention would be of significant utility. 
     The following review of the operation of a conventional mobile oil recycling system is intended to facilitate an understanding of the present invention. 
     FIG. 1 is a cross-sectional view of a conventional mobile oil recycling system  20 . The conventional system  20  includes an evaporation unit  22  and a filter  24 . Oil enters the refining system  20  via an oil inlet  26  screwed into the side of the evaporation unit  22 . The oil inlet  26  carries pressurized oil from an engine (not shown) and deposits the oil in a first hollow space  28  between the filter  24  and the evaporation unit  22 . The oil then flows through a filter element  30  that removes solid contaminants down to one micron in size. 
     After solid contaminants are removed from the oil via the filter  30 , the oil passes into a second hollow space  32 . Then, the pressurized oil passes through a metering orifice  34  where the oil pressure changes to atmospheric pressure from engine pressure. The metering orifice  34  serves to restrict the flow of the pressurized oil. Oil passing through the orifice  34  enters a third hollow space  36 . From the third hollow space  36 , the oil flows through oil channels (shown in phantom) into an evaporation compartment  40 . Then, the oil flows across a small, flat evaporation surface  38  in the evaporation compartment  40 . The evaporation surface  38  is heated by an electric heating element  42 . The heating element  42  is powered by electricity from an engine alternator, or a battery. 
     The oil disperses into a film over the heated surface  38 , which facilitates the evaporation of gas and liquid contaminants from the oil. Evaporated gases and liquids are vented via a vent  44 . The vent  44  is typically connected to an engine air intake (not shown) allowing contaminant gases and liquid vapors to be re-burnt in the engine. 
     Oil coagulates at the bottom of the evaporation compartment  40 . Gravity then pulls the oil back to the engine via a gravity feed oil return  48 . Because the oil return  48  exits the side of the system  20  and not the bottom, oil coagulates at a bottom  46  of the evaporation compartment  40 . This coagulation minimizes the effective surface area of the heated surface  38 , and increases the susceptibility of the compartment  50  backing up with oil and overflowing out the vent  44 . 
     The first hollow space  28 , the second hollow space  32 , and the third hollow space  36  all illustrate an inefficient use of space. The large metallic evaporation unit  22  is both heavy and bulky, which complicates installation and increases the cost of the system  20 . The system  20  must be mounted using very sturdy metal brackets and screws, which are expensive, bulky, and require a near flat mounting surface, which is difficult to find under the hoods of modern automobiles. In addition, the heating element  42  is an expensive, often unreliable and dangerous component. Also, the evaporation surface  38  is small and does not extend to the top of the compartment  40 . As a result, the surface  38  is inefficient and illustrates additional wasted space in the compartment  40 . 
     In a similar oil recycling system (not shown) the oil inlet  26  is placed in the bottom of the filter  24 , and the second hollow space  32  is replaced by filter element. In this system, dirty oil in the filter  24  flows back to the engine causing unwanted fluctuations in oil pressure and oil levels in addition to re-contaminating the engine oil. This decreases the efficiency of such systems. 
     FIG. 2 is cross-sectional view of a mobile oil recycling system  50  constructed in accordance with the teachings of the present invention. The system  50  includes a cylindrical liquid and gas removal chamber  54  surrounded by a low-micron, gradient-density filter  52  that is contained in a system housing  56 . The filter  52  may be ordered from a filter supply house, such as Harrington Industrial Plastics. The bulky evaporation unit (see  22  of FIG. 1) of conventional mobile oil recycling systems is replaced by the liquid and gas removal chamber  54  corresponding to the second hollow space (see  32  of FIG.  1 ). The removal of gas and liquid contaminants by the system  50  is based on surface area and pressure gradients rather than electrical heating. It is widely known that the rate of evaporation of a liquid is proportional to the surface area of the liquid. By expanding the surface area of a liquid, the rate of evaporation of the liquid will increase correspondingly. 
     In the present specific embodiment, the system  50  is adapted for use with high-grade synthetic oil that is resistant to breakdown. The synthetic oil enters the system  50  via an oil inlet  58  in a base  60  of the system housing  56 . The inlet  58  includes a hollow tube  61  having an inlet orifice  62 . Pressurized oil entering the system  50  via the inlet  58  passes through the tube  61  and out the orifice  62 . The inlet orifice  62  shoots pressurized oil into a high velocity stream (not shown) tangent to the surface of the filter  52 . The high velocity stream creates an oil circulation  64  in a centrifuge chamber  66  between the filter  52  and the system housing  56 . The circulation  64  results in a centrifugal force that causes large particles  68  to flow to an outside wall  70  of the housing  56  and subsequently fall to the base  60  of the housing  56 . This increases the life of the filter  52  and the time between filter changes. 
     Those skilled in the art will appreciate that the metering orifice  62  may be omitted without departing from the scope of the present invention. The tube  61  may be extended, and the metering orifice  62  may be elevated. In addition, a pre-filter may be attached to the oil inlet  58 . Also, the inlet  58  may be located in another part of the housing  56  such as in the wall  70  or in the cap  72 . 
     Oil in the chamber  66  is held at engine pressure in part by a cap  72  that screws on to the system housing  56 . Oil flows from the centrifugal chamber  66  through the filter  52  and toward a cylindrical filter support wall  74  that has holes  78 . The filter support wall  74  is a tube that is screwed into the base  60 . Those skilled in the art will appreciate that the support wall  74  may be a part of the housing  56  or base  60  without departing from the scope of the present invention. In addition, the chamber  66  may be at approximately atmospheric pressure without departing from the scope of the present invention. 
     Oil passing through the filter  52  enters the contaminant removal chamber  54  via the holes  78 . The oil is released from a first pressure, such as approximately engine pressure, to atmospheric pressure as it passes through the holes  78 . The contaminant removal chamber  54  is at atmospheric pressure. Clean oil flows out of the chamber  54  and back to the engine via an oil outlet  82 . Gravity pulls oil out of the chamber  54  and back to the engine or engine oil pan. The holes  78  are drilled sufficiently small so that the rate of oil entering the chamber  54  and the rate of oil exiting the chamber  54  equalize, preventing the chamber  54  from filling up with oil. By locating the gravity return  82  at the bottom of the system  50 , oil circulation through the system  50  is enhanced. 
     A special evaporation surface  80  exists on the inside of the support wall  74 . The surface  80  is ridged and textured to maximize the surface area of the surface  80 . The surface area of the surface  80  is orders of magnitude larger than the corresponding evaporation surface area (shown in FIG. 1 as  38 ) of conventional mobile recycling devices. The extra size of the evaporation surface  80  obviates the need for an electric heater element. Heat from the operating environment of the engine is sufficient to allow the evaporation of contaminant liquids and the removal of contaminant gases from the oil via the evaporation surface  80 . The textured evaporation surface  80  allows the system  50  to be installed on automobiles at a near horizontal angle, since channeling, which would limit the effective surface area, is limited by the textured surface. A screen, mesh, or other device may be fitted over the surface  80  for further increasing the effective evaporation surface area of the contaminant removal chamber  54 . Hence, the lightweight, space-efficient system  50  may be easily strapped to engine components at a variety of angles, making installation easy and cost-effective. 
     The end cap  72  is screwed onto the housing  56 . The end cap  72  is sealed against the top surface of the wall  74  via a washer  84 , closing off the contaminant removal chamber  54 . The cap  72  also contains grooves  88  for facilitating gripping of the cap  72 . The contaminant removal chamber  54  includes a vent  86  for venting vaporized liquid contaminants from the chamber  54 . In the present specific embodiment, the vent  86  includes a check valve to prevent oil from exiting the chamber  54  in case of an oil flow imbalance. The vent  86  is directed to an air intake (not shown). 
     In the present specific embodiment the filter  52  is a high-quality one-micron gradient-density filter that may be ordered from a filter supply house. The varying density of the filter  52  provides for a more uniform dirt distribution, greatly extending the life of the filter  52 . 
     When installing the system  50 , the oil inlet  58  is connected to an engine pressure tap, such as an oil pressure sending unit. The oil outlet  82  is connected to an oil pan or valve cover operating at or near atmospheric pressure. Those skilled in the art will appreciate that check valves and flow control valves may be stalled on the oil inlet  58  and the oil outlet  82  to further control the flow of oil to and from the system  50 . In addition, a sleeve made of rubber or some other insulator may be fitted over the housing  56  to reduce heat loss from the system  50 . 
     In the present embodiment, the housing  56 , the end cap  72 , and the filter supporting wall  74  are constructed of a lightweight metal alloy, and may be manufactured at a conventional machine shop. All materials are heat-resistant and corrosion-resistant. 
     Unlike the system  20  of FIG. 1, which has an undesirable oil heating effect, the system  50  has a desirable oil cooling effect. The oil sweats out liquid contaminants in the chamber  54 . This has an oil cooling effect as contaminant molecules having high kinetic energies evaporate. This lowers the average kinetic energy of molecules in the oil and thus the temperature of the oil. 
     FIG. 3 is a cross-sectional view of a recycling system  50 ′ constructed in accordance with the present invention. An electric heating coil  90  is embedded in a wall  74 ′. The embedding may be performed at a conventional machine shop. The wall  74 ′ includes a first cylindrical wall  75  and a concentric second cylindrical wall  77  having a smaller radius than the first wall  75 . The coil  90  is rapped around the second cylindrical wall  77 . The first wall  75  is placed adjacent to the second wall  77 , forming a coil space  79  where the coil  90  resides. The coil  90  has a conventional protective sleeve (not shown) that prevents oil from contacting the coil  90  itself. The holes  78  are fitted with conventional oil resistant sleeves  81  to prevent oil from entering the coil space  79 . The concentric walls  75 ,  77  are sealed at the top by the ring washer  84 . 
     The coil  90  has a resistivity and voltage differential sufficient to heat the chamber  54  to 195 degrees Fahrenheit and may be powered by an engine alternator (not shown), battery (not shown), or other means. The heat from the coil  90  facilitates contaminant evaporation from the surface  80  when oil from the oil inlet  58  is not sufficiently hot to separate liquid and gas contaminants from the oil on the surface  80 . 
     The coil  90  acts as an electromagnet in accordance with Faraday&#39;s Law of Electromagnetic Induction. The magnetic field acts to remove any remaining metallic particles from the oil. 
     Those skilled in the art will appreciate that the coil space  79  may be filled with an oil resistant epoxy after the coil  90  is wrapped around the second wall and before the holes  78  are drilled. This obviates the need for the protective coil sleeve (not shown) and the oil resistant sleeves  81 . In addition, the coil  90  may be replaced by a different type of heater; the coil  90  may extend partially up the wall  78 ; or a pre-heater may be attached to the inlet  58 , without departing from the scope of the present invention. Also, a permanent magnet may be used in place of the coil  90  to achieve magnetic filtration. 
     FIG. 4 is a cross-sectional view of an alternative embodiment  100  of the present invention including a spin-on filter  102  having a spin-on filter canister  103 . The filter  102  is a filter of conventional design with the exception that the filter  102  includes a special interior surface  104  and a vapor vent  106 . 
     The filter  102  is screwed onto a base plate  108  that includes an oil outlet  82  and an oil inlet  112 . Pressurized oil from an engine (not shown) enters the filter  102  through a base plate  108 . Oil passes through a filtering element  114  included in the filter  102 , where solid contaminants are removed, and some liquid contaminants are absorbed and/or neutralized. The pressurized oil, free of solid contaminants, is released to atmospheric pressure as it passes through the special surface  104  via small holes  116 . The holes  116  are drilled sufficiently small to prevent oil from backing up inside the filter  102 . This change in pressure facilitates vaporization of liquid contaminants and the separation and removal of gas contaminants from the oil. The special surface  104  is grooved and roughened for facilitating the dispersion of oil across the surface  104 . Oil disperses into a thin film across the surface  104 , where the oil that has been heated by the engine releases any liquid or gas contaminants. The oil then flows out of the alternative embodiment  100  via the oil outlet  82  in the base plate  108 . 
     FIG. 5 is a cross-sectional view of an illustrative embodiment  120  of the present invention adapted for use with a conventional spin-on filter  122 . The illustrative embodiment  120  includes a plate  124  and an evaporation attachment  126 . The attachment  126  is a tube having a textured inside surface  128  with holes  130  and is screwed into the plate  124 . Oil cleaned by the filter  102  may flow through the holes  130  and over a top  132  of the evaporation attachment  126 . Those skilled in the art will appreciate that oil flow may be prevented from flowing over the top  132  without departing from the scope of the present invention. 
     The operation of the illustrative embodiment  120  is analogous to the operation of the alternative embodiment of FIG. 4 with the exception that vapors vaporized from the surface  128  may exit through the plate  124  instead of the top of the filter  120 . The plate  124  has a vapor outlet  134 . A vapor tube  136  extends from the vapor outlet  134  and opens into the evaporation attachment  126 . In the present embodiment, the vapor tube  136  includes a ball valve  138  to prevent oil from escaping out the vapor outlet  134  via the vapor tube  136 . 
     FIG. 6 is a cross-sectional view of a second alternative embodiment  150  of the present invention. The system  150  includes a filter  152  surrounded by an expanded evaporation surface  156 . 
     Heated, pressurized oil enters the system  50  via an oil inlet  112 ′. Oil flows through the filter  152  and onto the evaporation surface  156  via the small holes  116 ′. Oil passing through the holes  116 ′ is released to atmospheric pressure, facilitating the vaporization of contaminants from the oil on the surface  156 . Vapors are vented through a vent hole  158  in a cap  157  and clean oil drains back to the engine (not shown) via an oil outlet  82 . 
     A groove  160  varies in depth around the circumference of the system  50 , helping to direct oil to the oil outlet  82 , and preventing oil coagulation in the groove  160 . 
     FIG. 7 is a cross-sectional view of a third alternative embodiment  170  of the present invention. The oil recycling system  170  includes an end cap  172 . The end cap  172  includes a pressure inlet  174  and an evaporation vent tube  176 . The vent tube  176  is made large to minimize the amount of vapor pressure required to vent liquid contaminants. A filter housing  178  screws onto the end cap  172  that seals to the housing at a first oil-tight seal  180 . The filter housing  178  has oil inlet passages  182  that feed pressurized oil from the oil inlet  174  to a low micron or sub-micron filtering media  184 . An evaporation/drainage assembly  186  screws into the bottom of the filter housing  178  and forms a second oil-tight seal  188 . The evaporation/drainage assembly  186  includes a threaded pipe  190  that extends into a center space partially surrounded by the filter media  184 . Threads  191  of the pipe  190  provide a large evaporation surface for oil entering the pipe from the filter media  184 . 
     Oil flows from the filter media  184  and over the top of the pipe  192 . The oil then flows over the threads  191  where vaporized contaminants pass out the vent tube  176 . The rate of oil flow through the oil recycling system  170  is controlled by a conventional flow control valve (not shown) connected to the oil inlet  174 . The flow of oil is controlled so that a thin film flows over the threads  191  in the pipe  190 . The depth of the film is on the order of the dimensions of the threads  191 . 
     The end cap  172  may be constructed at an ordinary machine shop. All other components or parts may be purchased separately at a hardware store or filter supply house. 
     The novel design of the present invention is facilitated by the unique combination of the end cap  172  with the evaporation/drainage assembly  186  which are easily adaptable to existing filter housings. 
     Those skilled in the art will appreciate that a co-linear embodiment of the present invention may be implemented wherein the filter and evaporation surface are not concentric without departing from the scope of the present invention. 
     Thus, the present invention has been described herein with reference to a particular embodiment for a particular application. Those having ordinary skill in the art and access to the present teachings will recognize additional modifications, applications, and embodiments within the scope thereof. 
     It is therefore intended by the appended claims to cover any and all such applications, modifications and embodiments within the scope of the present invention. 
     Accordingly,