건설차량용 반자동 변속기 유압제어계의 성능 개선

In this study, as a strategy to improve shift characteristics, the authors developed a new style pressure modulator which can reduce shock torque during power shift by modulating the pattern of pressure increase in the cylinder for actuating the clutch. The remarkable merits of this new pressure modulator lie in its structural simplicity and durability, because the modulator is only composed of a poppet type valve and a few orifices. The usefulness of the new pressure modulator is confirmed by experiments and numerical analyses on a clutch control hydraulic system simpli- fied for easy test. Also, the excellency of the transmission with the new pressure modulator is veri- fied by experiments on a test bench for simulating the running power train of an excavator.