Abstract:
A novel engine is provided with a crankshaft that is offset from a centerline of the bore shaft, where a reciprocally sliding piston is disposed. A curved or angularly shaped connecting rod is pivotably connected to the piston at one end and to the crankshaft at the opposite end. The position of the crankshaft and the shape of the connecting rod maximize the travel of the connecting rod through the piston stroke in relation to the overall size of the connecting rod. The design permits maximum compression to be achieved after the top dead center of the crankshaft to further promote engine efficiency.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to engines and more particularly to an engine having at least one curved or angular connecting rod that couples at least one piston to a crankshaft, which is offset from a centerline that extends through the piston bore. 
   2. Description of the Prior Art 
   Engines of having various designs and configurations power automobiles, lawn mowers, generators, compressors, and more. Most internal combustion engines are comprised of similar components, which typically include a block, a crankshaft, a piston and a connecting rod that couples the piston with the crankshaft. The connecting rod is crucial in that it transfers the reciprocating power of the piston to the rotating crankshaft. The most common connecting rod design is straight, rotatably connected at one end to a wrist pin in the piston and at the other end to a crankpin on the crankshaft. Many prior art engine designs have attempted to increase efficiency and power by altering the length and configuration of the connecting rods. 
   One prior art engine design uses a compound connecting rod having separate upper and lower connecting rod sections that are pivotably coupled to one another at one end. The opposite ends of the rod sections are coupled to the piston and crankshaft. A separate sleeve is disposed beneath the piston and is attached to the lower rod section at a pivot point. This design provides an improved level of engine efficiency but increases the overall number of component parts and the likelihood of mechanical failure. Moreover, the complex geometry and multiple pivot points of the compound linkage create increased manufacturing and maintenance costs. 
   Other prior art designs attempt to increase the functional length of the connecting rods by slidably mounting a piston slide within the piston skirt or in the piston crown. This arrangement provides a pivot point for the connecting rod that is independent of the piston wrist pin and compensates for cyclic changes in the connecting rod effective length. However, much like the compound connecting rods, this connecting rod design is overly complex, suffering from manufacturing and maintenance costs that outweigh the benefits gained in power and efficiency. Reliability of an engine is oftentimes more important than modest gains in performance. 
   Accordingly, what is needed is an engine design that provides increased levels of efficiency and power without increasing relative manufacturing and maintenance costs or decreasing reliability. Such an engine design should also be able to provide desired output ranges with a reduced overall engine size. 
   SUMMARY OF THE INVENTION 
   The engine assembly of the present invention is generally provided with a block having at least one cylinder, a crankshaft rotatably coupled with said block, a piston slidably disposed within the cylinder, and a connecting rod that couples the piston to the crankshaft. The connecting rod is provided with an elongated body portion that extends between opposite ends. The body of the connecting rod has at least one bend along its length so that a portion of the centerline of the body is angularly and laterally spaced from an axis that extends through the opposite ends of the connecting rod. In a preferred embodiment, the crankshaft is rotatably coupled with the block so that the centerline of said crankshaft is horizontally spaced from a bore centerline of the cylinder. The displaced position of the crankshaft works in concert with the bend in the connecting rod to maximize the effective length of the connecting rod and produce a maximum compression just past top dead center. 
   It is therefore a principal object of the present invention to provide an engine having angular or curved connecting rods that maximize the power and efficiency of the engine by maximizing the effective length of the connecting rod. 
   A further object of the present invention is to provide an engine that combines curved or angular connecting rods with a crankshaft that is displaced from a centerline of the engine&#39;s piston bore to maximize the effective length of the connecting rods. 
   Still another object of the present invention is to provide an engine having one-piece, angular or curved connecting rods that permit the engine to be arranged in an inline, “V” or opposed cylinder configuration. 
   Yet another object of the present invention is to provide an engine having increased overall efficiency and reduced overall size. 
   A further object of the present invention is to provide an engine having an increased overall efficiency that is simple in design. 
   Still another object of the present invention is to provide an engine having an increased overall efficiency with relatively low manufacturing and maintenance costs. 
   These and other objects of the present invention will be apparent to those having skill in the art. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front elevation view of one preferred embodiment of an engine of the present invention having a connecting rod and offset crankshaft assembly as the same could be positioned toward the beginning of a power stroke; 
       FIG. 2  is a front elevation view of the engine depicted in  FIG. 1  as the connecting rod and crankshaft assembly could be positioned near bottom dead center; 
       FIG. 3  is a front elevation view of the engine depicted in  FIG. 1  as the connecting rod and crankshaft assembly could be positioned toward the beginning of an exhaust stroke; 
       FIG. 4  is a front elevation view of the engine depicted in  FIG. 1  as the connecting rod and crankshaft assembly could be positioned near top dead center; 
       FIG. 5  is an isometric, partially disassembled view of one embodiment of a piston, connecting rod and crankshaft assembly of the present invention; and 
       FIG. 6  is a front elevation view of another preferred embodiment of an engine of the present invention having a curved connecting rod and offset crankshaft assembly, as the same could be positioned near top dead center. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   In the following detailed description of exemplary embodiments, reference is made to accompanying  FIGS. 1–6 , which form a part hereof and show, by way of illustration, exemplary embodiments of the present invention. These embodiments are disclosed in sufficient detail to enable those skilled in the art to practice the invention. It is to be understood that other embodiments may be utilized, however, and other changes may be made without departing from the spirit or scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense in that the scope of the present invention is defined only by the appended claims. 
   The engine  10  of the present invention is generally provided with a block  12  having at least one cylinder  14 , which is defined by interior walls of the block  12  and a cylinder head  16 . For ease of explanation only, the engine  10  will be described as having a single cylinder. However, it is contemplated that the present invention will also apply to engines having multiple cylinders and various configurations thereof. For example, the engine  10  of the present invention could be provided in the form of a multi-cylinder inline engine, a V configuration engine, or an opposed cylinder engine. 
   A piston  18  is slidably disposed within the cylinder  14 . The piston  18  may be of typical configuration, having a crown  20  and a piston skirt  22 . Accordingly, depending upon the particular application in which the engine  10  will function, piston rings  24  of various configurations may be employed for a ceiling engagement between the piston  8  and the walls of the cylinder  14 . However, other methods of providing a sufficiently sealed engagement are contemplated. 
   A crankshaft  26  is rotatably coupled with the block  12  and is provided with a main  28  that extends along a centerline of the crankshaft  26 . At least one crankarm  30  extends radially from the crankshaft  26 . In a preferred embodiment, the crankshaft is positioned with respect to the block  12  so that the main  28 , or centerline, of the crankshaft  26  is horizontally spaced from a centerline of the bore of the cylinder  14 . Examples of this configuration are depicted in  FIGS. 1–4  and  6 . The displacement of the crankshaft&#39;s  26  centerline from the centerline of the cylinder  14  may be accomplished with minor design modifications to inline engine blocks, V configured engine blocks and even opposed cylinder engine blocks. 
   A connecting rod  32 , having a first end portion  34  and a second end portion  36  is provided for operatively coupling the piston  18  with the crankshaft  26 . Specifically, the first end portion  34  of the connecting rod  32  is rotatably coupled with the piston  18 . In one preferred embodiment, the first end portion  34  is rotatably coupled to a wrist pin  38  that extends through the piston skirt of the piston  18 . However, it is contemplated that a similarly structured, rotatable connection may be provided using other forms of connectors and may even be rotatably coupled within the piston crown  20 . The second end portion  36  of the connecting rod  32  is rotatably coupled, in a preferred embodiment, with a crankpin  40  that is disposed at the distal end of the crankarm  30 . In this structural arrangement, bearings  42  and caps  44  are contemplated but may be replaced by equivalently functioning structures. For example, the second end portion  36  may be provided in a one-piece construction. 
   A body portion  46  of the connecting rod  32  extends between the first end portion  34  and the second end portion  36 . The body portion  46  is provided with at least one bend along its length so that a centerline of the body portion  46  is angularly and laterally spaced from an axis that extends through the first end portion  34  and the second end portion  36 . Preferably, the displacement of the body portion&#39;s  46  centerline from the axis extending between the opposite ends of the connecting rod  32  occurs at least adjacent the apex of the bend. It is contemplated that the bend in the body portion  46  could be angular, as depicted in  FIGS. 1–5 . The specific angle may range from obtuse to acute and will depend upon the configuration of the block  12  and the desired application for the engine  10 . Other considerations will certainly include the shape and configuration of the components to the crankshaft  26 . In an alternate embodiment, depicted in  FIG. 6 , the bend may be relatively smooth and curved in nature. 
   In a preferred embodiment, the connecting rod  32  and the crankshaft  26  are shaped and coupled with one another so that the piston  18  is cycled through a reciprocating piston stroke, having a predefined distance, as the crankshaft  26  is rotated. In a preferred embodiment, the bend in the body portion  46  of the connecting rod  32  defines a base leg  48  that extends from the second end portion  36  to the apex of the bend and a main leg  50  that extends from the first end portion  34  to the apex of the bend. The base leg  48  and main leg  50  are preferably formed to be rigidly adjoined to one another adjacent the apex of the bend. Accordingly, a one-piece construction is contemplated between the base leg  48  and main leg  50 , but is not crucial, so long as they are rigidly joined to one another. In one preferred embodiment, the base leg  48  is provided with a length that approximates half the distance of the piston stroke. Likewise, the crankarm  30  could be provided with a length that approximates half the distance of the piston stroke. Where both the crankarm  30  and the base leg  48  are provided in this manner, their combined lengths will approximate the total length or distance of the piston stroke. Changes to the lengths of either or both of the crankarm  30  and the base leg  48  are contemplated in order to accommodate different configurations of the engine block  12  or other relevant design aspects dictated by the application chosen for the engine  10 . 
   One preferred configuration for the engine  10  is depicted in  FIGS. 1–4  as the engine  10  is cycled from the beginning portion of a power stroke through a beginning portion of an exhaust stroke. In this manner the shape of the connecting rod  32 , the displaced position of the crankshaft  26  and their structural orientation with one another can be easily viewed. The advantages of these arrangements will be clear to those of skill in the art. For example,  FIG. 4  demonstrates that, in a preferred embodiment, top dead center of the piston  18  occurs after the top dead center (or point of maximum elevation of the crankarm  30 ) of the crankshaft  26 , thereby providing an increased effective momentarm of the crankarm  30  throw at the moment of combustion and maximum pressure within the cylinder  14 . The effective momentarm of the crankarm  30  is longer during the initial combustion period when maximum cylinder pressure is experienced. Accordingly, mechanical and thermodynamic efficiency are increased along with the torque, as measured at the crankshaft  26 . The shape of the body portion  46  of the connecting rod  32  further extends the period of high compression, or dwell, due to the fact that the piston  18  will tend to “stall” in its positions of top dead center and bottom dead center. Accordingly, overall efficiency of the engine  10  is improved by ensuring that the fuel is more completely burned and exhaust gases are more completely expelled from the cylinder  14 . The engine  10  will also tend to operate more quietly and produce less pollutants due to the constant volume burn achieved by the geometry and orientation of the connecting rod  32  and the crankshaft  26 . 
   In the drawings and in the specification, there have been set forth preferred embodiments of the invention and although specific items are employed, these are used in a generic and descriptive sense only and not for purposes of limitation. Changes in the form and proportion of parts, as well as a substitution of equivalents, are contemplated as circumstances may suggest or render expedient without departing from the spirit or scope of the invention as further defined in the following claims. 
   Thus it can be seen that the invention accomplishes at least all of its stated objectives.