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Model testing of the internal leaks of valve body in automatic transmission

Dziubak T., Szczepaniak P.

Journal of KONES

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2017

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Vol. 24, No. 3

71--78

EN

The article presents the working conditions and the functions of the ATF fluid in an automatic transmission. It was noted that the correct operation of the automatic transmission is heavily influenced by the quality of the ATF fluid, which operates in disadvantageous conditions of oxidising environment, is subject to contamination and undergoes intense shearing, thus changing its physical and chemical properties during use. The analysis included the disadvantageous, from the point of view of loss of fluid pressure in the automatic transmission’s hydraulic system, phenomenon of the fluid’s flow through fractures (clearances) of the hydraulic precise pairs “called the rate of flow through internal leaks” or an “internal leak”. The model of the rate of flow through internal leaks was proposed to determine the impact of the precise pairs’ wear and the hydraulic fluid’s properties on the aggregated leaks in the hydraulic system controller of the automatic transmission. The modelling utilised the dependency between the rate of flow through internal leaks of the hydraulic precise pair and the coaxial circular fracture. The model’s assumptions were formulated. The values of clearances of the electrohydraulic controller’s precise pairs were determined during the measurements of the actual structure – based on the automatic transmission’s mileage. The measurements featured relevant diameters of pushers and sliders, as well as internal diameters of cylindrical openings of manifold sliders and hydraulic suppressors. Variant model testing was conducted with various degrees of the fluid’s wear and temperature (viscosity and density) for conditions of driving with transmission “1” and “2”.

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Wear processes in precise pairs of hydraulic control devices

Ułanowicz L.

Journal of KONES

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2016

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Vol. 23, No. 1

405--412

EN

One of the most important tasks in a complex of activities aimed at increasing the use quality of a hydraulic drive are studies concerning the impact of operating conditions of hydraulic precise pairs on their durability. With supercritical values of the slide velocity, there is a stepwise and rapid quantitative characteristics of the wear process on the surface of a hydraulic precise pair’s elements. The phenomenon of wear by oxidation and the occurrence of adhesive seizing (tacking), created in the course of the process of mutual impact of surfaces of hydraulic precise pairs in control devices, under load resulting from a hydraulic drive’s pressure pulsation requires thorough consideration. The paper discusses operating conditions of slider pairs of hydraulic control devices associated with the kinetics of their movement and their load conditions. They were supported by results of empirical studies. General characteristics and mechanism of the wear by oxidation in a slider control pair was presented. The impact of loss of stability of a control spring in a slider control pair and the relative displacement of pair’s elements during the operating process, on the character and intensity of the adhesive seizing event were discussed. The conditions of occurrence of adhesive seizing in hydraulic slider pairs, under load resulting from pressure pulsation in a hydraulic drive were discussed.

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Modelling of a process, which causes adhesive seizing (tacking) in precise pairs of hydraulic control devices

Ułanowicz L.

Eksploatacja i Niezawodność

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2016

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Vol. 18, no. 4

492--500

EN

Lack of complete knowledge in the scope of the impact of operating conditions of precise pairs of hydraulic units on the character of the destructive processes arising in them, results in not taking these conditions into account at the early stages of design and manufacturing. One of such little described issues are factors causing adhesive seizing (tacking), created during the process of interaction between slider surfaces of pairs of hydraulic control devices under contact-vibration load. The articles presents general characteristics and mechanisms causing adhesive seizing (tacking) in precise pairs of hydraulic control devices under contactvibration load. It also presents a model describing the process, which causes adhesive seizing (tacking) in a slider hydraulic pair under contact-vibration load. The model allows to carry out both, qualitative, as well as quantitative analysis of the impact of vibration and load parameters on the occurrence of adhesive seizing (tacking) in slider pairs of hydraulic control devices. Practical application of the model requires the determination of the values of coefficients, which characterise the intensity of restoration and seizing resistance of metal oxides on cooperating surfaces of a hydraulic pair. An empirical method for estimating coefficients of the model and an example of estimating model coefficients for a pressure increase limiter were presented.

PL

Brak pełnej wiedzy w zakresie wpływu warunków pracy par precyzyjnych zespołów hydraulicznych na charakter powstawania w nich procesów destrukcyjnych powoduje, że na etapach projektowania i wytwarzania nie uwzględnia się tych warunków. Jednym z takich mało opisanych zagadnień są czynniki wywołujące zacieranie adhezyjne (sczepianie), powstające w procesie wzajemnego oddziaływania powierzchni suwakowych par hydraulicznych urządzeń regulacyjnych przy obciążeniu kontaktowo-wibracyjnym. W artykule przedstawiono ogólną charakterystykę i mechanizmy wywołujące zacieranie adhezyjne (sczepianie) w hydraulicznych parach precyzyjnych urządzeń regulacyjnych przy obciążeniu kontaktowo-wibracyjnym. Zaprezentowano model opisujący proces wywołujący zacieranie adhezyjne w suwakowej parze hydraulicznej przy jej obciążeniu kontaktowo – wibracyjnym. Model pozwala przeprowadzić zarówno jakościową, jak i ilościową analizę wpływu parametrów wibracji i obciążenia na wystąpienie zacierania adhezyjnego (sczepiania) w suwakowych parach hydraulicznych urządzeń regulacyjnych. Praktyczne wykorzystanie modelu wymaga określenia wartości współczynników charakteryzujących intensywność odtwarzania i opór ścierania tlenków metalu ze współpracujących powierzchni pary hydraulicznej. Przedstawiono empiryczną metodę szacowania współczynników modelu i przykład szacowania współczynników modelu dla ogranicznika narastania ciśnienia.