Abstract:
An apparatus for draining oil from an engine. The apparatus includes an engine having an engine housing, crankshaft, a piston, and an oil reservoir, an engine starting mechanism configured to engage the crankshaft and piston, a check valve configured to prevent pressure in a crankcase from escaping and configured to allow filtered air into the engine, and a selector valve configured to open a flow path between the check valve and a vent so oil can be drained.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to lubrication systems for an internal combustion engine. More specifically, the invention relates to an oil removal system and method for an engine. 
       BACKGROUND OF THE INVENTION 
       [0002]    In internal combustion engines, including engines used in a lawnmower, a snowblower, or other outdoor power equipment, the oil should be periodically drained and changed to maintain optimal engine performance. In these applications, the engine is typically mounted to a frame, such as a mower deck. When it is necessary to drain the engine oil, the oil is typically drained through a drain hole located near the bottom of the engine or tilting the equipment such that the oil can drain from the drain hole. Such methods require manipulation of sometimes heavy equipment and the use of gravity to drain the oil, and often result in spillage. 
       SUMMARY 
       [0003]    In one embodiment, the invention provides an apparatus for draining oil from an engine. The apparatus includes an engine having an engine housing, crankshaft, a piston, and an oil reservoir, an engine starting mechanism configured to engage the crankshaft, a check valve configured to prevent pressure in a crankcase from escaping and configured to allow filtered air into the engine, and a selector valve configured to open a flow path between the check valve and a vent so oil can be drained. 
         [0004]    In another embodiment the invention provides a method for draining oil from an engine. The method includes moving a selector valve from a normal engine operation position to an oil drain position, activating an engine starting mechanism, opening a flow path between a check valve and a vent, and creating positive pressure to force oil from the engine. 
         [0005]    Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a perspective view of a lawnmower having an embodiment of the present invention. 
           [0007]      FIG. 2  is a schematic of an oil removal system embodying the present invention. 
           [0008]      FIG. 3  is a perspective view of an engine housing having an oil drain hole. 
           [0009]      FIG. 4  is another perspective view of a drilled passage for oil removal. 
           [0010]      FIG. 5  is a side view of the drilled passage for oil removal. 
           [0011]      FIG. 6  is a graphical illustration of oil evacuation time based on volume of oil. 
       
    
    
     DETAILED DESCRIPTION 
       [0012]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms “mounted,” “connected,” “supported,” and “coupled” and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, “connected” and “coupled” are not restricted to physical or mechanical connections or couplings. 
         [0013]      FIG. 1  illustrates a lawnmower  10  having an internal combustion engine  14  with a starting mechanism  18 . The engine  14  is shown as powering a lawnmower, but the engine could be adapted for any situation in which a small engine is required. For example, the engine could be used to power other lawn and garden equipment, outdoor power equipment, augers, cultivators, a pump of a pressure washer or to power a generator. The starting mechanism  18  is shown as a recoil starter configured for manipulation by an equipment operator. However, the starting mechanism can be an electric starter or other type of starting mechanism. 
         [0014]    As illustrated in  FIG. 2 , the engine  14  includes an engine housing  22 , a breather  26 , an air cleaner  30 , a selector valve  34 , a crankshaft assembly  38 , and a piston  42 . The engine housing  22  is adapted to at least partially rotatably support a crankshaft assembly  38  in a crankcase  46 . The engine housing  22  also includes an oil reservoir  50  to collect engine oil. Breather  26  includes a check valve  54   a  configured to vent the engine crankcase  46  to the engine air cleaner  30 , while also preventing reverse oil flow, such that an oil mist will not escape the engine. During engine operation, the piston  42  is configured to slidingly reciprocate in the engine cylinder  78 . The sliding motion of the piston  42  creates pressure within the engine  14  to enable combustion and control pressure-induced engine functions. 
         [0015]    The selector valve  34  is configured for manipulation by an equipment operator. The selector valve has a first position  58  and a second position  62 . The first position  58  corresponds to the normal engine operating condition, wherein the equipment operator uses the equipment. The second position  62  corresponds to an oil drain condition, during which the equipment operator drains the oil from the engine  14  according to the present invention. In the illustrated embodiment, the selector valve  34  is a single valve with two positions. However, in other embodiments, the selector valve may have a plurality of ports and a plurality of positions. Alternatively, the selector valve could include a first valve for the normal engine operation and a distinct second valve for oil drainage. 
         [0016]    As illustrated in  FIGS. 2-4 , the engine housing  22  includes an oil port  66  configured for oil drainage. The oil port  66  is preferably a passage  70  formed through the lowest point of the engine housing  22  to permit maximum drainage. However, the oil port  66  can be a passage  70  formed at other locations in the engine housing  22  in which the passage  70  allows oil to drain. The oil port  66  can be drilled or formed by another type of manufacturing process. In some embodiments, a pick-up tube  86  ( FIG. 5 ) can be utilized to allow oil drainage to the oil port  66  from the lowest points of the engine housing  22 . The oil port  66  includes a shut-off valve  74  positioned on the exterior of the engine housing  22 . The shut-off valve  74  closes the oil port  66  to prevent unwanted oil drainage when the selector valve  34  is in the first position  58 . 
         [0017]    In other embodiments, the oil port includes a quick-disconnect sleeve  90 . The quick-disconnect sleeve  90  enables the equipment operator to attach a plastic tube or a plastic bag to the quick-disconnect sleeve to collect the oil for disposal. In some embodiments, the plastic bag includes a cover to close the oil drain hole of the plastic bag, thereby enabling the plastic bag to be used for multiple oil collections and drainages. In still other embodiments, the oil passage includes a spout or faucet for use with the quick-disconnect sleeve. The spout enables oil drainage and collection in a pan or other oil disposal receptacle. 
         [0018]    Under standard engine operation, the selector valve  34  is in the first position  58 . When the piston  42  travels downward in the cylinder  78  toward crankcase  46 , the positive pressure is released because the breather  26  functions as a check valve  54   a  positioned to allow gas pressure to escape. The breather  26  also has a separator that reduces the amount of oil entrained in the vented crankcase gases. 
         [0019]    To accomplish oil drainage from the engine  14 , the engine  14  functions as a pump. More specifically, the engine starting mechanism  18  and piston  42  act in conjunction as a pump to pump out the oil, thereby eliminating the need for a separate pump to accomplish engine oil drainage. To drain oil from the engine  14 , the selector valve  34  is moved to the second position  62  and engine ignition is prevented by either disconnecting the ignition wire(s) or grounding the ignition signals. In the second position  62 , check valve  54   b  opens a unidirectional flow path  55  from the air filter  30  to engine crankcase  46 , such that a positive pressure is built up in the crankcase  46  during oil drainage. The build-up of positive pressure forces oil out of the engine  14  through passages  70  or  86  and then through oil port  66 . The selector valve  34  preferably includes an electrical ground switch  82  to ground the engine ignition while the selector valve  34  is in the second position  62  to prevent engine ignition while the engine oil is draining. With the selector valve  34  in the second position  62 , oil drainage is initiated by manipulation of the starting mechanism  18 . Pulling of the recoil starter or engaging the electric starter by the equipment operator causes positive pressure to build in the crankcase  46 , forcing the oil out of the crankcase through the oil port  66 . 
         [0020]    The typical oil capacity of a small, single cylinder, internal combustion engine is about 16-20 ounces. In an engine with an oil capacity of 18 ounces, approximately five pulls on a manual recoil starter will force about 12-14 ounces of oil out of the engine housing the present invention. Approximately ten pulls will force the maximum amount of oil from the engine housing the present invention, whereby approximately three ounces of oil will remain in the engine housing following oil evacuation. 
         [0021]    With the engine  14  and piston  42  operating as a pump, using the engine starting mechanism  18  provides a low-cost alternative to having a separate pump to drain the engine oil. 
         [0022]      FIG. 6  graphically illustrates test data showing the volume of oil evacuated versus the crank time. The test samples included straight grade SAE  30  oil at 230 degrees Fahrenheit and control sample oil having the viscosity of hot oil, but which was tested at room temperature.  FIG. 6  shows that the amount of oil evacuated from the oil reservoir levels off as the crank time increases. The pressure generated for oil drainage is high enough to accomplish oil drainage, yet low enough so as not to exceed the engine specifications (e.g., for the gaskets). 
         [0023]    Various features and advantages of the invention are set forth in the following claims.