Abstract:
A cover for a crankcase of an internal combustion engine is disclosed. The cover has an inside surface in which walls are formed extending from the inside surface to form channels. A plate covers the channels to form passages that allow the flow of oil from various inlets to various outlets in the passages, but does not necessarily completely seal the channels. The plate is secured to the inside surface of the cover by threaded members that are inserted through fastening apertures in the plate and are threaded into corresponding internally threaded apertures in the inside surface of the cover.

Description:
FIELD OF THE INVENTION 
   The present invention relates to internal combustion engines. In particular, the present invention relates to covers for crankcases within internal combustion engines and the oil passages with the covers. 
   BACKGROUND OF THE INVENTION 
   Internal combustion engines contain a crankcase, which typically houses many of the internal workings of the engine such as the crankshaft, cams, counterweights, and various gears. The crankcase is also used to collect and hold the oil or other lubricant used in the engine. The accumulated oil is transferred from the crankcase, typically through an oil filter, is delivered to various engine parts for lubrication, and is then returned to the crankcase. 
   Many engines currently use splash lubrication and/or rolling element bearings to deliver oil from the crankcase to the various engine parts. These methods are typically used because they are fairly simple and avoid the complexity of full pressure oil circuits. However, the disadvantage of these methods is that they do not have the capacity of full pressure oil circuits and typically suffer from higher wear. Therefore, it is desirable to use a full pressure oil circuit to maintain the capacity and durability of the oil delivery system. 
   A full pressure oil circuit typically delivers oil from an oil pump to various engine parts under pressure. In order to do this, the circuit that the oil follows must be enclosed as to maintain the oil under pressure throughout the oil circuit. 
   One way to create a full pressure oil circuit in an internal combustion engine is to create passages within the crankcase itself. Two designs for this type of oil circuit are disclosed in U.S. Pat. No. 4,285,309, which issued on Aug. 25, 1981, to Rolf A. G. Johansson, and U.S. Pat. No. 4,926,814, which issued on May 22, 1990, to Kevin G. Bonde. In both of these patents, there are passages integral to the crankcase itself. 
   In the Johansson patent, channels are made in the upper surface of the crankcase. Similarly, in the Bonde patent, multiple walls are formed in the top wall of the crankcase defining multiple channels. In both patents, the channels are then enclosed when the crankcase is assembled with an upper housing forming multiple passages. However, the designs in both the Johansson and the Bonde patents have certain disadvantages. In particular, if the upper housing and the upper surface of the crankcase do not fit perfectly, there will be some leaking of the oil. In these designs, any oil that leaks will leak out of the crankcase and be lost. 
   Another disadvantage is that the channels in both designs must either be machined into the upper portion of the crankcase or be molded integral with the crankcase. If the channels are machined, at least one additional step is added to the manufacture of the crankcase, which costs extra time and expense. If the channels are molded integral with the crankcase, the die for the crankcase becomes more complicated and costly and may require die-slides that will increase the cost of the die itself and will not allow dies for multiple parts. In addition, once the basic shapes of the channels are formed, there may be additional machining steps required to complete the full passages. 
   One way to overcome these disadvantages is to create passages within the crankcase cover rather than the crankcase itself. By having the passages in the crankcase cover, any oil that may leak from the passages is returned to the crankcase rather than leaking out of the crankcase and being lost. In addition, the manufacture of the crankcase itself is not complicated by requiring large upper surfaces, extra machining steps, or complicated and inefficient die molds. 
   One common way to create passages with a cover is to use oil tubes that are cast directly into the cover. However, molding a cover using cast in oil tubes is an extremely complex process, is expensive, and can lead to poor quality such as porosity around the oil tubes. In addition, once the cover has been cast with the oil tubes, the cover requires extra machining to eliminate any burrs on the oil tubes and many designs require extremely long drillings in order to complete the full oil circuit. Finally, the mold dies required for crankcase covers with cast in oil tubes are typically expensive and complicated because they require die-slides, they do not allow for molding multiple parts on a single die tool, and the molding procedures are complicated. 
   It would therefore be advantageous if a crankcase cover could be designed that contained passages that allowed the use of a full pressure oil circuit without the use of cast in oil tubes. In particular, it would be advantageous if the crankcase cover was easily manufactured, without the need for extra machining steps or long drillings, and could be manufactured with simple mold dies which do not include die-slides and allow for the manufacture of multiple parts on a single mold die to simplify and reduce the cost of the manufacture of the cover. 
   SUMMARY OF THE INVENTION 
   The present inventors have discovered a crankcase cover design that can be used in a full pressure oil circuit in which multiple walls are molded directly into the cover itself forming multiple channels. The channels are then enclosed by a plate that is secured to the cover thereby forming multiple passages within the cover. Because the passages are formed in the cover, any oil that may leak from the passages is merely returned to the crankcase to be reused rather than leaking out of the crankcase all together. In addition, because the channels are formed by walls molded into the cover, the manufacture of the cover is simplified and the cost of manufacture is reduced. The mold die can be a simple open and close die that does not require any die-slides, molded in parts, or other complicated molding procedures, multiple parts can be made from a single mold die for better casting economy, and no extra machining steps or complicated drillings are required. 
   In particular, the present invention relates to a cover for the crankcase of an internal combustion engine that has a channel formed in the inside surface of the cover body and a means for covering the channel to form a passage that has an inlet and an outlet. 
   The present invention further relates to a crankcase of an internal combustion engine that has a body formed by a floor and side walls. The floor and side walls define an interior volume. The floor and each of the side walls has an interior surface facing the interior volume and the side walls each have an end surface opposite the floor. The end surfaces of the side walls define an opening in the body which is covered by a cover body having an inside surface facing the interior volume. The cover has a channel formed in the inside surface of the cover and a means for covering the channel to form a passage that has an inlet and an outlet. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a first perspective view of a single cylinder engine, taken from a side of the engine on which are located a starter and cylinder head. 
       FIG. 2  is a second perspective view of the single cylinder engine of  FIG. 1 , taken from a side of the engine on which are located an air cleaner and oil filter. 
       FIG. 3  is a third perspective view of the single cylinder engine of  FIG. 1 , in which certain parts of the engine have been removed to reveal additional internal parts of the engine. 
       FIG. 4  is a fourth perspective view of the single cylinder engine of  FIG. 1 , in which certain parts of the engine have been removed to reveal additional internal parts of the engine. 
       FIG. 5  is fifth perspective view of portions of the single cylinder engine of  FIG. 1 , in which a top of the crankcase has been removed to reveal an interior of the crankcase. 
       FIG. 6  is a sixth perspective view of portions of the single cylinder engine of  FIG. 1 , in which the top of the crankcase is shown exploded from the bottom of the crankcase; 
       FIG. 7  is a top view of the single cylinder engine of  FIG. 1 , showing internal components of the engine in grayscale. 
       FIG. 8  is a first perspective view of a crank case cover of the single cylinder engine of FIG.  1 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to  FIGS. 1 and 2 , a new single cylinder, 4-stroke, internal combustion engine  100  designed by Kohler Co. of Kohler, Wis. includes a crankcase  110  and a blower housing  120 , inside of which are a fan  130  and a flywheel  140 . The engine  100  further includes a starter  150 , a cylinder  160 , a cylinder head  170 , and a rocker arm cover  180 . Attached to the cylinder head  170  are an air exhaust port  190  shown in  FIGS. 1 and 2  and an air intake port  200  shown in  FIGS. 2 and 3 . As is well known in the art, during operation of the engine  100 , a piston  210  (see  FIG. 7 ) moves back and forth within the cylinder  160  towards and away from the cylinder head  170 . The movement of the piston  210  in turn causes rotation of a crankshaft  220  (see FIG.  7 ), as well as rotation of the fan  130  and the flywheel  140 , which are coupled to the crankshaft. The rotation of the fan  130  cools the engine, and the rotation of the flywheel  140 , causes a relatively constant rotational momentum to be maintained. 
   Referring specifically to  FIG. 2 , the engine  100  further includes an air filter  230  coupled to the air intake port  200 , which filters the air required by the engine prior to the providing of the air to the cylinder head  170 . The air provided to the air intake port  200  is communicated into the cylinder  160  by way of the cylinder head  170 , and exits the engine by flowing from the cylinder  160  through the cylinder head  170  and then out of the air exhaust port  190 . The inflow and outflow of air into and out of the cylinder  160  by way of the cylinder head  170  is governed by an input valve  240  and an output valve  250 , respectively (see FIG.  7 ). Also as shown in  FIG. 2 , the engine  100  includes an oil filter  260  through which the oil of the engine  100  is passed and filtered. Specifically, the oil filter  260  is coupled to the crankcase  110  by way of incoming and outgoing lines  270 ,  280 , respectively, whereby pressurized oil is provided into the oil filter  260  and then is returned from the oil filter  260  to the crankcase  110 . 
   Referring to  FIGS. 3 and 4 , the engine  100  is shown with the blower housing  120  removed to expose a cover  290  of the crankcase  110 . With respect to  FIG. 3 , in which both the fan  130  and the flywheel  140  are also removed, a coil  300  is shown that generates an electric current based upon rotation of the fan  130  and/or the flywheel  140 , which together operate as a magneto. Additionally, the cover  290  of the crankcase  110  is shown to have a pair of lobes  310  that cover a pair of gears  320  (see FIGS.  5  and  7 - 8 ). With respect to  FIG. 4 , the fan  130  and the flywheel  140  are shown above the cover  290  of the crankcase  110 . Additionally,  FIG. 4  shows the engine  100  without the cylinder head  170  and without the rocker arm cover  180 , to more clearly reveal a pair of tubes  330  through which extend a pair of respective push rods  340 . The push rods  340  extend between a pair of respective rocker arms  350  and a pair of cams (not shown) within the crankcase  110 , as discussed further below. 
   Turning to  FIGS. 5 and 6 , the engine  100  is shown with the cover  290  of the crankcase  110  removed from a body  370  of the crankcase  110  to reveal an interior volume  380  of the crankcase. Additionally in  FIGS. 5 and 6 , the engine  100  is shown in cut-away to exclude portions of the engine that extend beyond the cylinder  160  such as the cylinder head  170 . With respect to  FIG. 6 , the cover  290  of the crankcase  110  is shown above the body  370  of the crankcase  110  in an exploded view. In this embodiment, the body  370  includes a floor  390  and side walls  400 . The side walls  400  of the crankcase  110  each have and interior surface  460  facing the interior volume  380  and an end surface  470  opposite and facing away from the floor  390 . The end surfaces  470  of the side walls  400  together define an opening  480  in the body  370  of the crankcase  110 . The cover  290  only acts as the roof of the crankcase  110  by covering the opening  480 . The cover  290  and body  370  are manufactured as two separate pieces such that, in order to open the crankcase  110 , one physically removes the cover  290  from the body  370 . Also, as shown in  FIG. 5 , the pair of gears  320  within the crankcase  110  are supported by and rotate upon respective shafts  410 , which in turn are supported by the body  370  of the crankcase  110 . 
   Referring to  FIG. 7 , a top view of the engine  100  is provided in which additional internal components of the engine are shown in grayscale. In particular,  FIG. 7  shows the piston  210  within the cylinder  160  to be coupled to the crankshaft  220  by a connecting rod  420 . The crankshaft  220  is in turn coupled to a rotating counterweight  430  and reciprocal weights  440 , which balance the forces exerted upon the crankshaft  220  by the piston  210 . The crankshaft  220  further is in contact with each of the gears  320 , and thus communicates rotational motion to the gears. In the present embodiment, the shafts  410  upon which the gears  320  are supported are capable of communicating oil from the floor  390  of the crankcase  110  (see  FIG. 5 ) upward to the gears  320 . The incoming line  270  to the oil filter  260  is coupled to one of the shafts  410  to receive oil, while the outgoing line  280  from the oil filter is coupled to the crankshaft  220  to provide lubrication thereto.  FIG. 7  further shows a spark plug  450  located on the cylinder head  170 , which provides sparks during power strokes of the engine to cause combustion to occur within the cylinder  160 . The electrical energy for the spark plug  450  is provided by the coil  300  (see FIG.  3 ). 
   In the present embodiment, the engine  100  is a vertical shaft engine capable of outputting 15-20 horsepower for implementation in a variety of consumer lawn and garden machinery such as lawn mowers. In alternate embodiments, the engine  100  can also be implemented as a horizontal shaft engine, be designed to output greater or lesser amounts of power, and/or be implemented in a variety of other types of machines, e.g., snow-blowers. Further, in alternate embodiments, the particular arrangement of parts within the engine  100  can vary from those shown and discussed above. For example, in one alternate embodiment, the cams could be located above the gears  320  rather than underneath the gears. 
   Referring to  FIG. 8 , a perspective view of the cover  290  is shown. The cover  290  has an inside surface  500  that faces the interior volume  380  when the cover  290  is assembled to the crankcase  110 . Walls  510  are molded directly into the cover  290  and extend from the inside surface  500  towards the interior volume  380 , forming channels  520  in the inside surface  500 . A plate  530  completely covers the channels  520  and forms passages (not shown) that allow the flow of oil or other fluids. The plate  530  does not necessarily have to completely seal the channels  520  because there is little consequence to minor leaking as any oil or other fluid that leaks from the passages will be returned to the crankcase  110 . Threaded members  580 , such are screws or bolts, are assembled through fastening apertures  590  in the plate  530  and thread into internally threaded apertures  600 , which are molded directly into the cover  290 , to secure the plate  530  to the inside surface  500  of the cover  290 . In alternate embodiments of the invention, other methods of securing the plate  530  to the inside surface  500  could be used, such as welding, adhesive, rivets, etc. 
   The passages allow the flow of oil or other fluids from the shafts  410 , through the oil filter  260 , and to crankshaft  110  and gears  320 . In addition, by varying the number and path of the passages, oil or other fluids could be distributed to any engine part requiring lubrication. Oil from one of the shafts  410  passes through a first inlet  540  in one passage, through the passage itself, and through an outlet  550  from the passage leading to the incoming line  270  of the oil filter  260 . From the oil filter  260 , the oil passes through the outlet line  280 , through a second inlet  560  in a second passage, through the passage itself, and is distributed to the crankshaft  110  and gears  320  via apertures  570  in the plate  530 . In alternate embodiments of the invention, other methods of distributing the oil or other fluid from the passages to various engine parts could also be used such as the use of nozzles, tubes, or other distribution devices. 
   In the present embodiment, the crankcase cover  290  has been designed for use with a single cylinder, 4-stroke, internal combustion engine. In alternate embodiments of the invention, the cover  290  can be used with any type of internal combustion engine by varying the number and path of the passages to distribute the oil or other fluid to various engine parts. 
   While the foregoing specification illustrates and describes the preferred emodiments of this invention, it is to be understood that the invention is not limited to the precise construction herein disclosed. The invention can be embodied in other specific forms without departing from the spirit or essential attributes of the invention. Accordingly, reference should be made to the following claims, rather than to the foregoing specification, as indicating the scope of the invention.