Influencing factors and valve leakage of YHCB type automotive arc pump valve sealing performance
The factors affecting the sealing performance of the valve are: 1 sealing surface quality; sealing surface width; 3 pressure difference before and after the valve; 4 sealing surface material and its treatment state; 5 dielectric properties; 6 surface lipophilic; 7 sealing oil film Exist; 8 rigid and structural features of the closure. The factors affecting the sealing performance of the YHCB-type automotive arc pump valve and the factors that affect the valve sealing performance of the valve leakage are:
1 sealing surface quality; 2 sealing surface width; 3 pressure difference before and after the valve; 4 sealing surface material and its treatment state; 5 medium properties; 6 surface lipophilicity; 7 the existence of sealing oil film; 8 the rigidity of the closing member Structural features.
(1) Influence of the quality of the sealing surface on the sealing performance of the valve The sealing surface of the valve refers to the portion where the valve seat and the closing member are in contact with each other to close. When the specific pressure on the sealing surface is below 40 MPa, the quality of the sealing surface plays a decisive role in the sealing performance of the valve. This is because when the specific pressure on the sealing surface is small and the surface roughness is low, the amount of leakage rapidly increases. When the specific pressure on the sealing surface is large, the influence of the surface roughness on the leakage amount is remarkably reduced.
(2) The influence of the sealing surface width on the sealing performance of the valve The width of the sealing surface determines the length of the capillary. When the width is increased, the movement stroke of the fluid along the capillary hole is lengthened, and the movement resistance of the YHCB type vehicle arc pump is increased. Increasing the width of the sealing surface reduces the erosion wear in the high pressure valve. When the width of the sealing surface is increased, Botaibang will increase the length of the leakage stroke proportionally, so that the leakage amount can be reduced proportionally. However, the width of the sealing surface is increased, and under the same sealing force, the sealing specific pressure is reduced, which increases the possibility of leakage. Therefore, the sealing face width cannot be increased indefinitely.
(3) The influence of the pressure difference between the valve and the valve on the sealing performance of the valve is theoretically analyzed. The pressure difference and the leakage amount before the valve are proportional to the leakage. However, the test proves that the YHCB-type on-board arc pump increases the leakage amount more than the pressure difference under the same conditions. The relationship between the amount of leakage and the pressure difference can be approximated by the following equation: G = M (N Δ P 2+ S ΔP) where: M, N, S - constant coefficient, these coefficients depend on the material, the sealing surface Processing quality, specific pressure on the sealing surface and other conditions; △ P - pressure difference.
(4) Influence of sealing surface material and its treatment state on valve sealing performance The sealing surface material and its treatment state have a great influence on the valve leakage. Since the size of the remaining gap between the sealing surfaces depends on the microscopic unevenness of the sealing surface, if the sealing ring of the steel material is used to cause the same degree of sealing, the YHCB type automotive arc pump must have a large specific pressure. The value must exceed the specific pressure of the seal made of brass. The surface treatment state associated with the seal, such as the deformation of the peaks, the change in size and seal gap, and other phenomena occur on the metal surface. It is obvious that the properties of the surface layer are significantly different from those of the base material. The change caused by the processing can affect the surface layer thickness of 50 μm. The base metal is not exposed during grinding. The work surface layer tissue is different from the metal matrix structure. Material properties have little effect on geometry and microgeometry. The difference in metal properties is usually less than the effects of other factors. This situation is even more pronounced when the sealing surface is operated under low pressure conditions. When the specific pressure is higher than 40 MPa, the influence of surface roughness on the sealing performance is reduced, and the influence of the material is increased.
(5) Influence of the properties of the medium on the sealing performance of the valve The influence of the liquid medium on the leakage amount is basically determined by the viscosity in the same sealing valve. Under the same conditions, the medium with high viscosity is smaller than the medium with small viscosity. many. The difference between the gaseous medium and the liquid medium is more pronounced (except for saturated steam, which is easy to ensure the sealing surface).
(6) Effect of surface lipophilicity on valve sealing performance Surface lipophilicity affects the amount of leakage due to the characteristics of capillary pores. When there is a thin oil film on the sealing surface, the YHCB type automotive arc pump needs to increase the pressure of the oil passing through the gap. Due to the good lipophilicity of the metal surface, kerosene can easily penetrate the gap between the casting and the sealing joint. Therefore, in some of the most critical situations, kerosene is used for the sealing hydraulic test. The sealing test was carried out by filling the kerosene in the cavity, which is equivalent to the oil tightness test at a pressure of 0.3 to 0.4 MPa.
(7) Influence of the presence of the sealing oil film on the sealing performance of the valve There is a sealing oil film between the sealing surfaces which has a significant influence on the sealing property. When there is a sealing oil film on the surface, the oleophilicity between the contact surfaces is destroyed, so that a large pressure difference is required to pass the medium through the capillary. In addition, a thick sealing oil film on the surface can block the passage of the medium and improve the sealing of the connection. When using oil film seals, it should be noted that the thickness of the oil film should be restored when the oil film is reduced during operation. The grease used in the valve is not allowed to dissolve in the medium, nor should it evaporate, harden or have other chemical changes.
(8) The rigidity and structural characteristics of the closure member affect the sealing performance of the valve. The rigidity and structural effects of the closure are due to the elastic action of the part. Since the closing member of the closed-circuit valve is not absolutely rigid, but has a certain elasticity, the size of the YHCB-type on-vehicle circular arc pump varies under the pressure associated with the medium, which also causes a change in the interaction of the sealing surface force. In order to compensate for the effect of these changes on the sealing performance of the closure member, it is preferred to have a smaller rigidity of the sealing surface, i.e., the elastic deformation is as large as possible.
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