Oil temperature influence on friction torque characteristics in hydraulic pumps

Abstract

This article presents a practical approach to the investigation of the influence of oil temperature on the friction torque in various types of hydraulic pumps using a mathematical model. Currently, an external gear, an internal gear or a vane pump is commonly used for an automatic transmission. These pumps have their own friction torque characteristics, which depend not only on pump-operating conditions such as operating pressures, pump speeds and oil temperature but also on structures and dimensions of the pumps. For various pumps, however, the friction torque characteristics can be represented by an identical mathematical model. In the pump-operating conditions, the oil temperature significantly and complicatedly affects them. The pump should be operated under conditions to obtain a higher mechanical efficiency, and the mathematical model is helpful to analyse how the oil temperature influences the friction torque. It is found that with an increase in oil temperature, the friction torque at a high pump speed decreases in a low oil temperature region, but it would not decrease in a high oil temperature region for all the tested pumps. This fact suggests that the pump overall efficiency would not improve at a high oil temperature, even if the volumetric efficiency does not go down.

Keywords

Fluid power system hydraulic pump friction torque mechanical efficiency mathematical model oil temperature

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References

Martin B, Redinger CJ and Dourra H. Chrysler 45RFE a new generation light truck automatic transmission. SAE paper 1999-01-1260, 1999.

Kunii

Sumi

. The development of a new lightweight, compact and high efficient CVT. Proc JASE Annu Congr 2002; 14(2): 1–4.

Neyrat S, Orand N and Jonquet D. Modeling and analysis of automatic transmission internal gear oil pump with cavitation. SAE paper 2005-01-2448, 2005.

Ozeki T and Umeyama M. Development of Toyota’s transaxle for mini-van hybrid vehicles. SAE paper 2002-01-0931, 2002.

Englisch

Faust

Homm

. Entwicklungs-potenziale für stufenlose Getriebe. ATZ 2003; 105(8): 676–685.

Shimizu K, Waki H, Saito T, et al. Development of a new-generation CVT with medium torque capacity for front-drive cars. SAE paper 2006-01-1306, 2006.

Ide T. Effect of belt loss and oil pump loss on the fueleconomy of a vehicle with a metal V-belt CVT. In:Proceedings of Seoul 2000 FISITA world automotivecongress, 12–15 June 2000, paper no. FA200A131, pp.1–6. Seoul: Korean Society of Automotive Engineers.

Kluger MA, Fussner DR and Roethler B. A performance comparison of various automatic transmission pumping systems. SAE paper 960424, 1996.

Kluger MA and Long DM. An overview of current automatic, manual and continuously variable transmissin efficiencies and their projected future improvements. SAE paper 1999-01-1259, 1999.

10.

Murrenhoff H, Piepenstock U and Kohmäscher T. Analysing losses in hydrostatic drives. In: Proceedings of the 7th JFPS international symposium on fluid power, Toyama Japan, 15–18 September 2008, paper no. OS4-1, pp.103–108.

11.

Wilson

. Rotary-pump theory. Trans ASME 1946; 68(4): 371–383.

12.

Wilson

. Performance criteria for positive-displacement pumps and fluid motors. Trans ASME 1949; 71(2): 115–120.

13.

Schlösser

WMJ

. Ein mathematisches Modell für Verdrängerpumpen und -motoren. Oelhydraulik und pneumatik 1961; 5(4): 122–129.

14.

Hibi

Ichikawa

. Mathematical model of the torque characteristics for hydraulic motors. Bull JSME 1977; 20(143): 616–621.

15.

Inaguma

Hibi

. Friction torque characteristics of a vane pump. J Jpn Hydraul Pneumatics Soc 1994; 25(7): 843–849. (in Japanese)).

16.

Inaguma Y, Watanabe K, Kato H, et al. Energy-saving and reduction of oil temperature rising in hydraulic power steering system. SAE paper 1999-01-0392, 1999.

17.

Inaguma

. Friction torque characteristics of an internal gear pump. Proc Inst Mech Eng Part C: J Mech Eng Sci 2011; 225: 1523–1534.

18.

Inaguma

Hibi

. Reduction of friction torque in vane pump by smoothing cam ring surface. Proc Inst Mech Eng Part C: J Mech Eng Sci 2007; 221: 527–534.