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This article proposes a rubber suspension bushing model considering amplitude dependence as a useful tool at the initial design phase. The purpose of this study is not to express physical phenomena accurately and in detail and to explore the truth academically, but to provide a useful design method for initial design phase. Experiments were carried out to verify several dynamic characteristics of rubber bushings under vibration up to a frequency of 100 Hz, which is an important frequency range when designing ride comfort performance. When dynamic characteristic theory and the geometrical properties of the force-displacement characteristic curve were considered using these dynamic characteristics as assumptions, an equation was derived that is capable of calculating the dynamic stiffness under an arbitrary amplitude by identifying only two general design parameters (dynamic stiffness and loss factor) under a reference amplitude.

The CVT offers high fuel economy, presumably because it ensures a low BSFC driving condition with its continuously variable ratio characteristics. Focusing solely on BSFC values, i.e., indices that represent the engine's thermal efficiency, is not enough, as substantial work loss occurs in the drivetrain, including the transmission and engine accessories, from the engine to wheels. Therefore, attention needs to be paid to the efficiency of the entire powerplant, including engine and transmission, rather than just focusing on engine thermal efficiency, as has been conventionally done. Engine and CVT controls should be integrated as in addition to the stoichiometric operation, an engine may be operated in modes of lean burn and exhaust-gas recirculation. This paper describes a newly developed algorithm for the calculation of the combinations between the engine torque and CVT ratio in order to achieve the highest overall efficiency for the engine and transmission system.