For more than 130 years, the crankshaft has been the mechanism utilized in internal combustion engines to convert the reciprocating linear motion of the pistons to rotary movement.
The CV design replaces the crankshaft with what we call the powershaft, which fundamentally alters the relationship of the motion of the piston stroke, the travel from top dead center (TDC) to bottom dead center (BDC), relative to the movement of the rotating shaft.
Crankshaft design engines are at the core of our industrial society, turning wheels in vehicles, spinning propellers in planes and boats, powering all manner of land, air and water based vehicles, moving air and fluids with pumps and/or compressors and powering devices as diverse as generators, cars, trucks, motorcycles, off-road and on-water recreational and commercial vehicles of all types, plus marine engines, both inboard and outboard, lawn and garden equipment, etc.
Modern crankshaft design has advanced significantly in terms of quality and durability, and the appendages connected to and/or related to the crankshaft design have evolved since its creation. As a result, power and fuel efficiency have been improved over time.
However, the mechanics of the crankshaft design, relating to the transfer of force of linear motion to rotational movement are simple but unchangeable. This presents a major shortcoming, as devices using crankshafts lose greater than 60% (sixty percent) of their mechanical transfer of power as a direct result of the inefficiencies associated with crankshaft geometry, and piston side load.
Lever arm length is the distance from the center of the rotating shaft to the point where the linear movement is applied. The lever arm length determines the amount of power transferred, from the force exerted on the piston, to the rotating shaft.
The CV design has its maximum lever arm length achieved within less than 10% of the piston stroke after TDC and maintains at maximum length until over 90% of stroke after TDC. The crankshaft does not achieve its maximum lever arm length until 43% after TDC and instantly decreases.
Additionally, in the crankshaft design, the shorter the connecting rod length, the greater the off-center angle force vector, which increases both friction, heat and wear between the cylinder wall and the piston, decreasing fuel efficiency while increasing emissions. This results in the diversion of the transfer of the linear piston force away from the rotational movement and therefore, less piston power is transferred to rotation.
The crankshaft design, because its maximum lever arm length is achieved only at about mid stroke, requires an over-fueling charge in order to make the presence of the expanding combustion gasses last to mid stroke. This is necessary to achieve transfer of power to the crankshaft from the piston force.
In the CV design, the maximum lever arm length is achieved just past TDC at about 8% of piston stroke. The duration of the maximum lever arm length is considerably longer than the same stroke crankshaft design. Therefore, the amount of fuel charge required to perform maximum transfer of power from the piston to the CV powershaft greatly reduces the amount of fuel used as compared to the same stroke crankshaft design. This is expected to produce greater than twice the fuel efficiency.
Two major components of the CV Engine are the moving parts (assemblies):
There is always total engagement between the rodrack and the powershaft throughout the stroke and the reversing stroke. The ramp up creates perfect alignment with the teeth, while providing additional strength at the highest concentration of force caused by combustion and stroke turn around. Restated, the ramp down provides controlled deceleration to zero and the ramp up provides controlled acceleration to gain proper speed for engagement of the reverse stroke.
The rodrack has two sets of teeth positioned at an offset from each side of the centerline of the linkrods, allowing for engagement with the powershaft. Each end of the rodrack connects to the linkrods using the turning shaft axle. This is also rigidly attached as if made of one piece. The top and bottom of the rodrack have machined parallel surfaces, which fit into bearings, which are mounted to the case. This provides for a precise linear movement of the rodrack assembly. The piston assemblies are mounted to the rodrack in a collinear position. The precise linear movement of the rodrack assembly maintains the pistons in the center of the cylinder in a collinear path. The rigid assembly is possible because there are no rotating linkages and unbalanced or eccentric loads.
The ideal engine would be comprised of two rodrack assemblies providing four cylinders (pistons). The linear direction of each rodrack would be opposite the other; this would help eliminate or counter balance their respective reciprocal forces. The CV Engine can be reduced to two opposing cylinders if necessary for a particular application.
The following images are: (A) a cut-away, and (B) an assembly for a four-cylinder CV Engine showing some of the key features. Image (A) is the complete assembly, and Image (B) is an assembly highlighting the patented replacement of the crankshaft with a rodrack connected directly to the pistons, moving as one unit.
In both images, the linear motion of the pistons act with a linear force directly upon the gold colored rodrack, which turns the gray powershaft, thereby, replacing the crankshaft to convert linear motion to rotary movement.
In order to better visualize the interaction of the rodrack and powershaft, a video of the operating CV engine can be viewed at www.youtube.com/watch?v=DtKRI-SPGNU or accessed directly from YouTube by searching for “CV Engine Concept in Slow Motion.”
The CVE can be configured as:
The key benefit of the CV design is the increase in delivered torque to the powershaft, with the maximum lever arm length for the longest period during the piston stroke and particularly at the most favorable period of the combustion process.
The cylinder pressure during combustion is greatest at the top of the piston stroke near top dead center (TDC). The graphic below is for an equal piston stroke and shows the relationship of the respective lever arms for the CV design and a crankshaft design. The crankshaft loses more than 50% of the potential torque and worse, is not at maximum until greater than 40% of the piston stroke. To restate this, the CV design cylinder pressure force on the piston is acting on a longer lever arm length for a longer period to produce more power/torque and earlier than a crankshaft design can with equal bore and stroke. Torque is a direct relationship to the length of the lever arm or throw of a crankshaft.
The crankshaft is at maximum torque for only an instant at greater than 40% of the piston stroke after TDC. The CV design has constant torque starting in less than 10% of stroke after TDC and maintains until over 90% of stroke after TDC. Further, the crankshaft lever arm is always 50% of the piston stroke where the CV design lever arm length is greater than 62% of the piston stroke. This relates to a 25% increase in lever arm length for the CV design.
The crankshaft mass, with piston cycling, induces pulsating harmonics and vibration. In addition, the variable lever arm length of the crankshaft results in a highly variable piston velocity throughout the piston stroke. The mass of the crankshaft is much greater than the piston; therefore, the piston must change its relative velocity. In contrast, the CV Engine piston is at constant velocity relative to the powershaft for nearly the entire piston stroke. Therefore, the pulsating harmonics and vibration are nearly eliminated, producing a smoother, more consistent power output. The powershaft in the CV design is smaller in diameter, more balanced and stronger than a crankshaft.
US Patent (Patents also held in EU, Japan, S. Korea and India)
The internal combustion engine has evolved for over 130 years (since the 1880’s) to a point where it has reached its limits of design efficiency. One of the inherent design inefficiencies is in the geometry of the crankshaft, which is used to convert the linear motion to rotational movement.
The crankshaft has an inherent mechanical loss in the amount of force applied to the top of the piston that converts to rotational torque. The crankshaft loses over 50% of the force generated, plus 10 to 20% friction for losses, that increases with speed.
The CV design has three major mechanical improvements over the crankshaft design. These improvements relate to much greater power output using less fuel and having much less harmful exhaust emissions than the crankshaft with the same bore and stroke.
The CV Engine can deliver its benefits in one of two equally attractive ways: