Fundamental Research on Gear Rattle (Effects of Mesh Stiffness Variation and Higher Harmonics of Driving Torque)

Introducing the mesh stiffness variation and higher harmonics of driving torque into the equation of motion of one pair of helical gear system, the effects of the mesh stiffness variation, the ratio of static torque to dynamic one and higher harmonics of driving torque on the rattle are studied by numerical analysis. As a result, the followings were made clear. (1) Because of interaction of dynamic torque and mesh stiffness variation, resonance occurs in low frequency region. (2) The ratio of static torque to dynamic one influences the occurrence of higher harmonic resonance. (3) When the dynamic torque is larger than the static one, vibration with larger amplitude than that of fundamental resonance occurs in extremely low frequency. (4) The acceleration amplitude of resonance at low frequency, and that of higher harmonic resonance are large enough and comparable to the amplitude of main resonance. (5) By the interaction of 1st harmonics and higher harmonics of driving torque, amplitudes of higher harmonic resonances become large. (6) When the higher harmonics exist in torque variation, region of chaos generation becomes wide.