Design of a Noncircular Gear Mechanism With Twice Unequal Amplitude Transmission Ratio

Abstract

This study proposes a new non–circular gear transmission mechanism with an involute–cycloid composite tooth profile to realize the twice unequal amplitude transmission (In a complete rotation cycle of gear transmission, instantaneous transmission ratio has twice fluctuations obvious with unequal amplitude) of non–circular gears. The twice unequal amplitude transmission ratio curve was designed based on Fourier and polynomial functions, the change law of the Fourier coefficient on the instantaneous transmission ratio(In non-circular gear transmission, the transmission ratio changes with time, and the transmission ratio of non-circular gear should be instantaneous transmission ratio) was analyzed, and the pressure angle and contact ratio of the involute–cycloid composite tooth profile was calculated. The involute–cycloid composite tooth profile non–circular gear was machined by WEDM technology, while its meshing experiment was performed using high-speed camera technology. The results demonstrate that the instantaneous transmission ratio curve value obtained via the high-speed camera experiment was consistent with the simulation value of virtual software. Furthermore, the involute–cycloid composite tooth profile was applied in the seedling pickup mechanism of non–circular gear planetary gear train. The possibility of the application of the involute–cycloid composite tooth profile in the seedling pickup mechanism was verified by comparing the consistency of the theoretical and simulated seedling picking trajectory.

WITHDRAWN: Design and application of non-circular gear with cusp pitch curve

“…The contact ratio [25] of the involute and incomplete cycloid profile is the ratio of its meshing line to its tooth pitch of non-circular gear with cusp pitch curve. The tooth pitch is different from the rotation direction of non-circular gear with cusp pitch curve in this paper, that is, the contact ratio of the involute and incomplete cycloid composite tooth profile designed in this paper is related to the rotation direction.…”

“…Contact ratio is an important characteristic for the feasibility of tooth profile design. It is the ratio of the length of the meshing line to the pitch [25]. The meshing line and contact ratio of anticlockwise rotation of incomplete variable cycloid tooth profile corresponding to different elliptical eccentricity are shown in Figures.…”

“…According to the theoretical transmission ratio curve shown in Figure 15(b) and center distance L=55.38 mm, the driving gear tooth profile is designed based on the design software in Figure 5, and the driven gear tooth profile is designed based on the envelope method [25], a non-circular gear transmission mechanism is designed, as shown in Figure 14. The transmission ratio curve in Figure 15 shows that the theoretical and simulated transmission ratio curves are almost the same.…”

“…The non-circular gear designed by this method has high quality and low precision, and its transmission accuracy is greatly affected by processing and assembly. At the early stage, the non-circular gear of pitch curve with small curvature radius was designed by use of the involute and cycloid composite tooth profile [25]. This involute and cycloid composite tooth profile has cusp at the tooth profile connection of the pitch curve, so using micro segments was necessary to modify the involute and cycloid at the tooth profile connection slightly, and the involute and cycloid composite tooth profile cannot solve the non-circular pitch curve with cusp.…”

Design and Application of Non-Circular Gear with Cusp Pitch Curve

“…The non-circular gear designed by this method has high quality and low precision, and its transmission accuracy is greatly affected by processing and assembly. At the early stage, the non-circular gear of the pitch curve with a small curvature radius was designed by use of the involute and cycloid composite tooth profile [32]. This involute and cycloid composite tooth profile has a cusp at the tooth profile connection of the pitch curve, so using micro-segments was necessary to modify the involute and cycloid at the tooth profile connection slightly.…”