# Kinematic and Dynamic Response of a Novel Engine Mechanism Design Driven by an Oscillation Arm
## 1 Introduction  
### Background  
The fleet of vehicles has expanded from year to year and has led to an undesired overall increasing of the exhaust emission and consumption. For this reason, engineers are pushed to improve and optimize the existing constructive solutions of current engines. Furthermore, the increased pressure on the engine manufacturers has imposed implementation in the production stream of some new constructive solutions for the current engine that must accomplish current standard requests imposed by the marketplace. This means an improvement of some parameters or engine characteristics, such as: increased power and torque and lower consumption and emissions, which allow to increase durability and reliability [1; 2; 3; 4; 5]. Generally, the efficiency of an engine with internal combustion is evaluated by means of characteristic processes on a cycle or based on some constructive parameters, such as: engine displacement, stroke-bore ratio and compression ratio. Furthermore, the efficiency can be evaluated based on the operational parameters (engine management, forming and controlling mixture air/combustible and ignition timing). One of the most representative concepts developed after year 2000 in order to meet these requirements is an engine constructive solution with satisfactory outcomes based on an oscillatory arm and variable compression ratio (VCR). The promoter of this solution was Dr. [PERSON] who after 11 years of research, implemented it on the Mayflower e3 engine for the first time [6; 7]. In this configuration, the compression ratio is a controllable parameter. Therefore, for this engine with internal combustion, the VCR technology [8] could be considered one of the keys that led tobetter performances both for partial loads and for the full loads of engines. This technology is based on a multi-link mechanism that allows to change the top and bottom dead center positions, which enable the compression ratio to be continuously changed [9]. It can provide higher compression ratio, variable valve timing, low friction, reduced throttling losses, boosting and down-sizing [10]. However, most benefits are related to minimal fuel consumption, minimal nitric oxides and particulate matter emissions [11]. To obtain superior performances, a cumulative method is required for improving the design process and final geometry, combustion process parameters [12; 13; 14; 15] type of fuel [16] and other environmental parameters. Other researchers have focused on VCR development and they have developed various technological solutions. In this sense, the SAAB has developed two concepts for the gasoline engine with natural aspiration: the engine with variable compression ratio SVC (Saab Variable Compression) and the system to control the combustion process SCC (Saab Combustion Control). Both solutions led to a reduction of consumption by 30%. The SVC system from SAAB allows continuous variation of the compression between 8:1 and 14:1 [17]. Another VCR solution developed by Peugeot is for the MCE-5 VCRi engine [18]; it has added an intermediary element in the form of a special gear. The system can change the compression ratio from 7:1 to 18:1, and the system can even control each cylinder separately, allowing all four cylinders to operate at different compression ratios. Gommecsys offered another VCR solution based on the possibility to rotate the crank axis, changing the position of the eccentric on the big end of the connecting rod. In this type of engine, an eccentric mounted carrier carries the crankshaft bearings that can rotate to raise or lower the pistons to the top dead center (TDC) in the cylinder. The compression ratio can be adjusted by just altering the rotation of the eccentric carrier. This technology saves fuel and overall CO\({}_{2}\) emission by 18% [19; 20; 21; 22; 23]. Nissan has achieved considerable success in the development of VCR engines over time [24; 25].