Abstract
When exposed to viscous heating, hydraulic valve orifices experience thermal deformation, which causes spool clamping and actuator disorder. Quantitative research on thermal deformation can help reveal the micro-mechanism of spool clamping. In this study, miniature thermocouples are embedded into a valve orifice with an opening size of 1 mm to measure temperature distribution. An optimization algorithm based on measurement data (M-OA) for the thermal deformation of the valve orifice is proposed. The temperature and thermal deformation of the valve orifice are calculated through Fluent and Workbench joint simulation, with the measurement data serving as boundary conditions. Results show that, for a valve orifice with a valve wall length of 18 mm, when the temperature of the sharp edge is at 60 °C, thermal deformation measures 7.7 μm via observation and 7.62803 μm via M-OA, indicating that the M-OA method is reliable. The results of the joint simulation can be accepted because measurements of temperature reached an accuracy rate of 95%, and that of deformation reached 82.7%. A large drop in pressure led to a rapid increase in temperature, causing serious thermal deformation of the valve orifice. With an inlet pressure of 3 MPa, the temperature of the sharp edge reached 72.9 °C within 110 min, and radial thermal deformation can reach 8.3 μm. Such deformation poses great risk of spool clamping for a spool valve of Φ36 mm.
Highlights
Hydraulic systems control the motions of actuators via hydraulic valves
Spool clamping is caused by two main factors: unexpected forces generated at macro level, such as flow force [1,2,3,4,5], and deterioration of lubrication clearance generated at micro level
When the sharp edge was at a temperature of implemented in calculating the thermal deformation of a hydraulic valve orifice with an uneven deformation results obtained via observation and M-OA
Summary
The most widely used type, exert a strong impact on the stability of actuators, and spool clamping leads directly to actuator disorder and even safety-related accidents. Spool clamping is caused by two main factors: unexpected forces generated at macro level, such as flow force [1,2,3,4,5], and deterioration of lubrication clearance generated at micro level. Barriers to achieving ideal clearance include factors such as roughness variation [8,9,10,11], particle pollution [12,13,14,15,16,17] and thermal deformation of valve orifices. Thermal deformation occurs when viscous heating generated by fluids increases the temperature of the valve orifice
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