Stationary Axial Flow Force Analysis on Compensated Spool Valves

Influence of Notch Shape and Number of Notches on the Metering Characteristics of Hydraulic Spool Valves

“…Several papers by the Authors were devoted to Computational Fluid Dynamics (CFD) simulation and to experimental verification of typical Downloaded by [University of Lethbridge] discharge coefficient values found in industrial components. They reported results on sharp edged geometries (Borghi et al, 1996(Borghi et al, , 1997(Borghi et al, and 1998, conic profile (Borghi et al, 1999) and on typical 'compensated' profile for the minimization of axial flow forces (Borghi et al, 2000). Work by Ellmann and Piche (1996) and Wu et al (2002), was concerned with developing a semiempirical expression describing the variability of the discharge coefficients in fixed-geometry orifices.…”

Pressure compensation using flow forces in a multi-section proportional directional control valve

“…Example solution of a proportional flow control valve with integrated pressure compensator is a KUDSR-type valve [1] or a QC-type valve [2]. Studies on the valves with integrated pressure compensator were conducted among others by Borghi [3] and Sheng et al [4]. Another possible solution is the use of electronic compensator, such as in [5,6].…”

“…. 3(-) x; x i spool displacement (mm) x g ; x g;i throttle gap width (mm) x ovr ; x ovr;i spool overlay (mm) p c;i pressure after ith section (MPa) Dp; Dp i pressure difference before and after valve/section (MPa) Q c;i ; DQ c;i control valve flow rate, flow error (dm3 /min) l i ; S i flow coeff. (-), gap area (m 2 ) m s;i spool mass (kg) F ss;i ; F ss0;i spring force, tension (N) max ; I i current intensity (A) G k ; G b ; Y M components (k-e) (J) C 1e ; C 2e ; C 3e constants (k-e) (-) s k ; s e Prandtl numbers (-) l t turbulent viscosity (Pa s) F x ; F y ; F z force components (N) Q p ; p p pump flow rate (dm 3 /min) and pump pressure (MPa) Q av ; Q pnom ; Q rel average, nominal, relief valve flow rate (dm 3 /min) in ; v out fluid velocity (m/s) a; b; a 2 ; b 2 ; h i coefficients (-) a in ; a out stream jet angle (°) k; k 2 flow force coeff., P-A, B-T position, the flow is cut off from all flow paths.…”

Effects of flow force on the characteristics of electrohydraulic servovalves

“…Reference [9][10], flow force was measured by direct measurement method. In [11,12], the research on the compensation flow forces on spool valves was shown. All the research works are mentioned above only describe the value of the flow force, but there is no research on the effects of flow forces on the servo valve performance.…”