Setting of model boundary conditions for 5mm right displacement of multi-channel valve rotary coupling valve core of excavator: the inlet speeds of old and new valves are set to 2.77m/s and 2.944m/s, and the outlet pressure is 0mpa, that is, the rotary motor is unloaded, the turbulence intensity is taken as 10%, and the inlet and outlet hydraulic diameters are 0.012m and 0.0085m respectively. (1) The static pressure distribution gives the static pressure cloud diagram of the axial section of the return oil of the valve core of the rotary coupling of the multi-way valve of the original excavator shifted to the right by 5mm (unit: MPa; hereinafter referred to as the original static pressure cloud diagram of the return oil shifted to the right by 5mm). The inlet pressure is up to 14MPa. After passing through the variable U-shaped throttling groove, the total pressure loss is 14MPa; After the pressure oil passes through the return U-shaped throttling groove, the pressure loss is 14MPa. There is no eddy current field in the throttling groove and no negative pressure is formed. The pressure loss is mainly at the position where the oil has just entered the orifice. The pressure gradient at the inlet is large and the pressure gradient at the outlet is small.
Static pressure nephogram of 5mm return oil axial section of multi-way valve rotary coupling valve core of new excavator (unit: MPa; hereinafter referred to as new 5mm return oil static pressure nephogram). The inlet pressure reaches 9.5Mpa. After passing through the variable U-shaped throttling groove, the total pressure loss is 9.5Mpa; After the pressure oil passes through the return U-shaped throttling groove, the pressure loss is 9.5Mpa. There is no eddy current field in the throttling groove and a local negative pressure is formed.
The pressure loss is mainly at the position where the oil has just entered the orifice. The pressure gradient at the inlet is large and the pressure gradient at the outlet is small.
(2) Velocity nephogram of 5mm oil return axial section of multi-way valve rotary coupling valve core of the original excavator moving right (unit: M / S; hereinafter referred to as the original 5mm oil return velocity nephogram moving right). The inlet speed is 10m / s. when the oil passes through the minimum part of the variable U-shaped throttling groove, the speed can reach 160m / S; After the pressure oil passes through the oil inlet U-shaped throttling groove, the speed increases rapidly from 10m / s to 160m / s, resulting in local temperature rise.
The velocity is mainly generated at the minimum overflow area of the throttling slot, which also conforms to the flow continuity equation, indicating the correctness of the flow field analysis. Local high speed leads to local temperature rise of the oil, which oxidizes the oil and produces local thermal expansion deformation of the valve body, resulting in valve jamming. Velocity nephogram of 5mm oil return axial section of multi-channel valve rotary coupling spool of new excavator moving right (unit: M / S; hereinafter referred to as new 5mm oil return velocity nephogram moving right). The inlet speed is 10m / s. when the oil passes through the minimum part of the variable U-shaped throttling groove, the speed can reach 120m / S; It can be clearly seen from figure b)
It is known that after the pressure oil passes through the oil inlet U-shaped throttling groove, the speed increases rapidly from 10m / s to 120m / s, resulting in local temperature rise.
The velocity is mainly generated at the minimum overflow area of the throttling slot, which also conforms to the flow continuity equation, indicating the correctness of the flow field analysis. Local high speed leads to local temperature rise of the oil, which oxidizes the oil, resulting in local valve body deformation and valve jamming.
Summary: through the comparative analysis of the static pressure nephogram and velocity nephogram of the new and old valve cores moving to the right by 5mm, it can be known that for the static pressure nephogram, the throttling damping of the new valve is less than that of the old valve, which can reduce the throttling energy loss; For the velocity cloud chart, the maximum throttling speed of the new valve is less than that of the old valve, indicating that under the same opening, its overflow area is slightly larger than that of the old valve.
