Patent ID: 8935120
Filing Date: 2015-01-13
Classification: F02D

Abstract:
1. A revolution increase-decrease determination device comprising: a frequency analysis unit configured to calculate, from an engine sound, a frequency signal at a predetermined frequency for each of predetermined time periods; a revolution determination unit configured to determine whether the number of engine revolutions is increasing or decreasing, by determining whether a phase of the frequency signal is increasing at an accelerating rate over time or decreasing at an accelerating rate over time; and a phase curve calculation unit configured to calculate a phase curve approximating temporal fluctuations in the phase of the frequency signal, wherein the revolution determination unit is configured to determine whether the number of engine revolutions is increasing or decreasing by determining, on the basis of a form of the phase curve, whether the phase of the frequency signal is increasing at the accelerating rate over time or decreasing at the accelerating rate over time.