Auslegung eines Synchrongelenks für den Einsatz in Schrägachsen-Axialkolbenmotoren

  • Design of a homokinetic joint for use in bent axis axial piston motors

Steinwede, Johannes; Jacobs, Georg (Thesis advisor); Schröder, Kai-Uwe (Thesis advisor)

1. Auflage. - Aachen : Verlagshaus Mainz GmbH (2021)
Dissertation / PhD Thesis

Dissertation, RWTH Aachen University, 2020

Abstract

Hydrostatic drives compete against other drive types for use in mobile machinery. The demand for higher speeds leads to a demand for high swivel angles in the widely used bent axis motors. Key point for successful high angle motors is the design of a homokinetic joint that synchronizes drive shaft and cylinder barrel. Starting from a neutral design process, three different motor concepts are derived, all using well established machine elements, but deliver high possible swivel angles. Two concepts make use of a ball-type homokinetic joint. one uses a doubled tripod joint. First, geometric parameters that affect the loads on the synchronous joint were identified. Analytic and empiric models are used to describe the joint load. The results were validated by comparing them to load measurements from the motors tested on a motor-generator test bench.To analyze the joint characteristics, the joints of all concepts were modelled, both using multi body simulation tools and/ or finite element tools where necessary. Special regard was set on failures in the angular transmission behavior, which can lead to torsional vibrations. Since lifetime calculation models for the chosen homokinetic joints only consider fatigue failures, the load capability of all joints were roughly estimated by testing. Joint testing was done in a joint test bench under close to real loads (hydraulic fluid, additional load forces, similar torque levels). Following the selection of a final motor concept, the motor with doubled tripods joint was analyzed for further load sources. First, the influence of the connected system on the joint load is analyzed by comparing results from a multi body simulation to measurement data. Second, the influence of the driven load cycle on the joint load is analyzed by comparing loads derived by real life data to generic testing cycles. The joint lifetime is obtained by comparing the load cycles to an estimated Woehler-curve from joint testing. Finally, a methodic approach is derived to describe an appropriate design process for the homokinetic joint with special regard on the universal usage of bent axis motors by respecting the different phases of product design and product application.

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