- An Idealised Fluid Coupling Mechanism Is Shown In Figure 1 Where An Input Velocity Drives A Fluid Loop Which Is Connecte 1 (328.08 KiB) Viewed 54 times
An idealised fluid coupling mechanism is shown in Figure 1 where an input velocity drives a fluid loop which is connected to a reservoir with pressure Po. The input velocity directly drives a fluid pump (KP) which feeds an accumulator. Fluid then flows from the accumulator through a hydraulic motor (Kn) via a fluid resistor. Flow through the hydraulic motor is controlled by a variable fluid resistor. The fluid system then drives a rotational mechanical system via a gearbox. Accumulator r2 Fluid resistor 天 Qp1 and 6 Wp Wh Win(t)- K Kh T1 Figure 1: A system containing electrical, mechanical and fluid-power elements. The CCRs of the fluid pump and hydraulic motor are all linear. The pump has CCRS 1 Qp = KpWp, AP= T) (1) Кр where Qp is the volumetric flow rate through the pump, APp is the pressure difference across the pump and Tp is the torque applied to the pump. Similarly, the hydraulic motor has CCRs Th = KAPh, wh = -Qh Kh (2) with similar definitions as above. a) (10%) Construct a bond graph for the system shown in Figure 1 and assign causal strokes to the graph. The reservoir pressure Po should be included in the bond graph (not omitted). b) (15%) Using your bond graph, determine a set of differential equations that describe the dynamic behaviour of the system. All components can be considered linear, except for the accumulator and fluid resistor. The fluid resistance is described by the nonlinear CCR Qα = Φ. (ΔΡ), where Qv and AP, are the volumetric flow rate through and pressure differential across the valve, respectively, and the fluid capacitor describes pressure as a nonlinear function of the volume according to Pa = Sa(Va), (3) where P, and V, are the pressure and volume of the accumulator, respectively.