IMPROVING THE EFFICIENCY OF A COMPACT INLINE HYDRO-MECHANICAL TRANSMISSION (I-HMT) AT LOCK-UP

Johnathan Hans Barkei, Perry Y. Li

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

A hydro-mechanical transmission (HMT) transmits power both mechanically and hydraulically allowing continuously variable transmission ratios and more efficient transmission than hydrostatic transmission. A conventional HMT tends to be costly and bulky since it has a hydrostatic transmission in parallel with a mechanical transmission. An alternative is a compact inline configuration that utilizes a two-shafted pump that is mechanically and hydraulically connected to a motor. This avoids the need for a planetary gear set while providing the HMT functionality. When the pump/motor displacement is zero, all of the power is transmitted mechanically and the transmission ratio is unity, a condition referred to as lock-up that is expected to be very efficient. Previous research however has shown significant losses at this operating condition in experiments. This is thought to be caused primarily by compressibility losses due to the repeated unnecessary opening and closing of the distributor valves. This paper first models the Hondamatic in simulations to confirm that compressibility losses contribute to the low efficiency at lock-up. Second, the paper proposes a solution to reduce these compressibility losses by means of a second cam mode that closes the distributor valves to prevent flow between the piston and the high and low pressure volumes. The performance of the existing inline HMT and the proposed solution at lock-up are modeled in simulations and compared. The results indicate a 10% increase in efficiency at lock-up.

Original languageEnglish (US)
Title of host publicationProceedings of ASME/BATH 2021 Symposium on Fluid Power and Motion Control, FPMC 2021
PublisherAmerican Society of Mechanical Engineers (ASME)
ISBN (Electronic)9780791885239
DOIs
StatePublished - 2021
EventASME/BATH 2021 Symposium on Fluid Power and Motion Control, FPMC 2021 - Virtual, Online
Duration: Oct 19 2021Oct 21 2021

Publication series

NameProceedings of ASME/BATH 2021 Symposium on Fluid Power and Motion Control, FPMC 2021

Conference

ConferenceASME/BATH 2021 Symposium on Fluid Power and Motion Control, FPMC 2021
CityVirtual, Online
Period10/19/2110/21/21

Bibliographical note

Publisher Copyright:
Copyright © 2021 by ASME.All right reserved.

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