1) Calculation model analysis of oil inlet and intermediate oil return when the valve core of multi-channel valve rotary coupling of excavator moves 4mm to the right setting of boundary conditions of the model: set the inlet speed as 10.04m/s and the outlet pressure as 0mpa, that is, the rotary motor has no load. The turbulence intensity is taken as 10%, and the inlet and outlet hydraulic diameters are 00073m and 0012m respectively.
(1) Static pressure distribution figure 42 shows the static pressure cloud diagram of the 4mm axial section of the rotary coupling valve core of the multi-channel valve of the original excavator (unit:
MPa; hereinafter referred to as the original 4mm static pressure cloud diagram shifted to the right) it can be seen from the a diagram that the inlet pressure reaches 2MPa, and the total pressure loss is 22Mpa after passing through the variable U-shaped throttling groove; It can be seen from figure b) that after the pressure oil passes through the oil inlet U-shaped throttling groove, the pressure loss is 22Mpa, which is due to the eddy current field at the upper part of the throttling groove and the local negative pressure, resulting in cavitation, which greatly affects the performance of the valve: it can be seen from figure C that after the pressure oil passes through the oil return U-shaped throttling groove, the pressure loss is 2MPa. The local negative pressure is relatively small, but at this time, the return oil overflow area is greater than the inlet oil overflow area, so the pressure loss is relatively small compared with the inlet U-shaped throttling groove. It can be seen from b) and C) that the pressure loss is mainly at the joint surface between the orifice and the inner cavity of the main valve core. The pressure gradient at the inlet is large and the pressure gradient at the outlet is small.
Figure 4-3 shows the static pressure cloud diagram of the 4mm axial section of the multi-way valve rotary coupling valve core of the new excavator (unit: MPa; hereinafter referred to as the new 4mm static pressure cloud diagram).
It can be seen from figure a) that the inlet pressure reaches 1MPa, and the total pressure loss is LPA after passing through the variable U-shaped throttling groove; it can be seen from figure b) that the pressure oil passes through the oil inlet U-shaped throttling groove, and the pressure loss is i|mpa, which is because there is a vortex field at the upper part of the throttling groove and a local negative pressure is formed, resulting in cavitation, which greatly affects the performance of the valve; It can be seen from Fig. C) that after the pressure oil passes through the oil return U-shaped throttling groove, the pressure loss is impa. The local negative pressure is small, but the overflow area is larger than the oil inlet overflow area, so the pressure loss is smaller than the oil inlet U-shaped throttling groove. It can be seen from b) and C) that the pressure loss is mainly at the joint surface between the orifice and the inner cavity of the main valve core. The pressure gradient at the inlet is large and the pressure gradient at the outlet is small.
(2) Velocity distribution
Fig. 44 shows the velocity cloud diagram of the 4mm axial section of the multi-channel valve rotary coupling valve core of the original excavator moving to the right (unit: s; hereinafter referred to as the original 4mm velocity cloud diagram moving to the right)
It can be seen from the a) diagram that the inlet speed is 10ms (the column diagram does not show the complete speed level). When the oil passes through the minimum position of the variable U-shaped throttling groove, the speed can reach 240ms; from the B) diagram, it can be seen that after the pressure oil passes through the oil inlet U-shaped throttling groove, the speed quickly increases from 40m / s to 240m, resulting in local temperature rise. It can also be seen from figure C) that after the pressure oil passes through the oil return U-shaped throttling groove, the speed increases rapidly from 20m / s to 240m / s, resulting in local temperature rise, and the area of oil high-speed area is larger than that of oil inlet state. It is known from b) and C) that 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.
Figure 45 shows the velocity cloud diagram of the 4mm axial section of the multi-channel valve rotary coupling valve core of the new excavator moving to the right (unit: M / S; hereinafter referred to as the new 4mm velocity cloud diagram moving to the right)
It can be seen from figure a) that the inlet speed is 10ms. When the oil passes through the minimum part of the variable U-shaped throttling groove, the speed can reach 100M / S; It can be seen from figure b) that after the pressure oil passes through the oil inlet U-shaped throttling groove, the speed increases rapidly from 40ms to 160ms, resulting in local temperature rise. It can also be seen from figure C) that after the pressure oil passes through the oil return U-shaped throttling groove, the speed increases rapidly from 30ms to 160ms, resulting in local temperature rise, and the area of the high-speed oil area is smaller than that of the oil inlet state. It is known from b) and C) that 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.
