Instantaneous speed fluctuations of thermal engines. Excitations applied to the crankshaft : Exact and approximate expressions for excitation torques

Exact and approximate expressions for excitation torques
Instantaneous speed fluctuations of thermal engines. Excitations applied to the crankshaft

Authors : Jean-Louis LIGIER, Elian BARON

Publication date: September 10, 2021 | Lire en français

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4. Exact and approximate expressions for excitation torques

As mentioned in the introduction to this article, the excitation torque can be estimated from a liner-piston or connecting rod-crankpin force. These two cases will be dealt with below. However, to avoid overloading the notations, no new index is used to differentiate between these two types of torque. They can be easily identified by reading the comments accompanying their literal expressions.

4.1 Couple notations

The crankshaft excitation torque is C_m. The torque C_vi corresponds to the contribution of inertia terms to the excitation torque, and C_vg to the contribution of gas terms. We therefore have :