New Concept of a Rocker Engine –– Kinematic Analysis

Abstract

The paper presents concept and design of a four-stroke 4-cylinder internal combustion engine consisted of a single connecting rod to a crankshaft and four additional rods joining pistons with a rocker. The rocker is a specific element in the engine construction that makes this engine different from the typical reciprocating internal combustion piston engine. Furthermore, kinematical analysis of this piston -rocker -crankshaft mechanism was conducted. As concluded from the analysis, this mechanism implemented to the engine, provides several advantages with respect to both dynamic and thermodynamic related issues. First of all, a profile of the piston motion can be easily changed with change in the mechanism geometry e.g. major dimensions of connecting rods, the rocker etc. Thus, the piston motion profile can be asymmetrical with slow motion to and relatively fast distancing from the TDC. This feature can be useful in reducing thermal losses to an engine cooling system. Additionally, the mechanism characterizes itself with low transverse force from the piston, which acts on a cylinder liner. As a result, it significantly reduces frictional losses and should increase the overall efficiency of the engine. Among disadvantages, higher inertial forces are the most important problem. As analyzed, the rocker is the main component that contributes to increase in inertial forces by approximately three to four times. On the other hand, total inertia forces, due to specific kinematical chain of the mechanism, can be remarkably reduced in case the mechanism is correctly optimized.

The Szymkowiak’s over-expanded cycle in the rocker engine with the variable compression ratio – kinematics

“…It is carried out on various levels, including the search for new kinematic solutions that enable the variable compression ratio and over-expanded cycle implementations into the engine. As a result, several solutions were invented to convert the reciprocating motion of the piston into the rotary motion of the crankshaft [1][2][3].…”

“…Its inventor is the Polish engineer Mirosław Szymkowiak. Szymkowiak has been working on his solutions for years [3] and as a result, he has achieved several improvements. The main feature of the developed mechanism is the rocker arm that connects two connecting rods: the first one is located between the piston and the rocker arm, the second one -between the rocker arm and the crankshaft, respectively.…”

Modelling of Combustion Characteristics of a Single Curved-Cylinder Spark-Ignition Crank-Rocker Engine

“…The idea and concept of toroidal engines have been around since the 1900s but have currently gained attention by researchers in both academia and industry. Some technical limitations resulting from the toroidal engines have been identified as follows [5]:…”

“…Recently, several new configurations of toroidal engines employing the concept of crank-rocker (CR) mechanism have been proposed by many researchers [5][6][7]. The crank-rocker mechanism can become one of the most promising new engine configurations due to its simplicity in design and manufacturing.…”