Research On Structure, Performance, Mechanism And Preparation Technology Of Automobile Oil Filtration Material

From perspective of market researches and literatures, we know that the preparation technology of automotive engine oil filter materials is mainly concentrated in foreign countries and oil filtration materials are mainly rely on imports due to its poor filtration efficiency and short service life of our own filtration materials. In order to meet the domestic market for automobile engine oil filtration materials and to break the foreign monopoly on engine oil filter material preparation technology, it is necessary to adopt new materials or technology to develop new filtration material and filter on the basis of our own research ability.(1) Based on the research of structure and performance of commonly used automobile engine oil filtration materials, we know that these oil filtration materials are porous materials which have good pore characteristics and disorderly arrangement fiber structures. To achieve better filtering effect, the oil filtration materials should have smaller fiber diameter and pore diameter, larger porosity, smaller weight and thickness, larger air permeability, breaking strength and breaking elongation. Through a deep analysis of structure and performance changes of automobile engine oil filtration material and air material before and after use, we know that the oil and air filtration materials of automobile after use both have decreased pore diameter and air permeability, increased thickness and weight.(2) Hemp fiber, viscose staple fiber and long-staple cotton fiber are used to develop hemp/cotton (60/40) spunlaced nonwoven, hemp/cotton (60/40) needled nonwoven, and hemp/viscose (60/40) spunlaced nonwoven, respectively. Meanwhile, the41.67tex hemp yarns are used to develop hemp plain weave fabric. Then three types of hemp nonwovens and hemp plain weave fabric are used to make a comparison of pore diameter, filtration accuracy and pressure drop. And the different hemp/cotton (60/40) spunlaced nonwovens are used to research the effect of filtration area on pressure drop. The hemp/cotton spunlaced nonwoven is also used to research the filtration property and the change of different parameters in the process of filtration. The flux of experimental oil and quality of impurity particles have great influence on the pressure drop, and the pressure drop increase with the increasing of flux of experimental oil and quality of impurity particles. Through an observing the SEM figures of hemp/cotton spunlaced nonwoven after filtration, we know that the particles can be trapped on the surface of single fiber or trapped in pores between two fibers. The concentration of impurity is in a dynamic change and filtration efficiency increase as the increasing of particle diameter in the process of filtration. Compared filtration properties with5#glass fiber nonwoven, the hemp/cotton spunlaced nonwoven has higher thickness, mass per square area and pore diameter, while smaller porosity. Compared filtration efficiency with experimental valuewe know the obvious difference between theoretical value of EI、EG、ES and experimental value E, and E,<E<EG, Es<<E. The filtration efficiency of theoretical value Es can be neglected due to the smaller value Es<<E. It can be found that interception mechanism and gravity deposition mechanism play a great role in filtration. Compared with standard automobile engine oil filter, we know that the hemp/cotton spunlaced nonwoven can be easily prepared into oil filter, while it is difficult to fold the hemp/cotton spunlaced nonwoven to form a better shape due to its higher folding gap and worse bonding effect.(3) The multi-layer porous composite materials are prepared to research the filtration effect. The PA6nanofiber layer is formed on the surface of hemp/viscose spunlaced nonwoven. The thickness and mass per square area are27.2μm and2.08g/m2, respectively. The results indicate that substrate layer+PA6nanofiber layer composite material has smaller pore diameter and better filtration effect than hemp/cotton spunlaced nonwoven. Compared with higher thickness0.82mm and mass per square area131.94g/m2of substrate layer, it can be found that the PA6nanofiber layer possesses smaller thickness and mass per square area. The adhesives have a higher influence on thickness and mass per square area of composite material than PA6nanofiber layer, while the PA6nanofiber layer has higher effect on filtration effect. Compared with two substrate layer composite material, the substrate layer+PA6nanofiber layer composite material has better filtration effect. Meanwhile, the filtration property of sandwich structure composite material is similar to5#glass fiber nonwoven, which possesses smaller thickness, mass per square area, pore diameter and better filtration effect. The sandwich structure composite material has better filtration effect than substrate layer+PA6nanofiber layer composite material. While the obvious slice phenomenon between substrate layer and PA6nanofiber layer can be solved by the sandwich structure. Compared of pressure drop with different composite materials without PA6nanofiber layer, the composite material including PA6nanofiber layer has higher pressure drop at different flux of clean experimental oil. The thickness, mass per square area, filtration effect and pressure drop increase as the increasing of the layer number of composite material.(4) The hemp paper is prepared after a series process of cutting, cooking, bleaching, defibering, beating, pulp making, squeezing and drying to research the filtration properties. The obvious and different pores can be observed from SEM figures of different hemp papers; moreover, some hemp fibers are cut off by the mechanical action of ZQS2-45pulper fly knife roller while others are not in the process of beating. The typical characteristic of vertical stripes can’t be seen from the surface of hemp fiber after the beating process. On the basis of constant value of mass per square area of hemp paper, the results indicate that the thickness of hemp paper decrease from163μm to132.4μm, the compactness of hemp paper increase from0.43g/cm3to0.53 g/cm3and the air permeability decrease from2.748μm/Pa·s to0.646μm/Pa·s as the increasing of beating degree. The filtration efficiency of hemp paper for0.33um particles in the oil and0.26μm NaCl aerosol particle increase as the increasing of beating degree. The filtration efficiency of different hemp papers for0.33μm particle in the oil and0.26μm NaCl aerosol particle comes to99.852%-99.958%and99.942%-99.973%, respectively. On the basis of constant value of beating degree (60°SR) of hemp paper, the results indicate that the thickness of hemp paper increase from132.4μm to174.88μm, the compactness of hemp paper increase from0.53g/cm3to0.633g/cm3and the air permeability decrease from0.646μm/Pa·s to0.276μm/Pa·s as the increasing of mass per square area. The results indicate that the thickness and compactness increase while the air permeability decrease as the increasing of mass per square area of hemp paper in the constant value of beating degree. The filtration efficiency of hemp paper for0.33μm particles in oil and filtration efficiency for0.26μm NaCl aerosol particle both have similar change. And the filtratin efficiency of hemp paper increase as the increasing of weight. The filtration efficiency of different hemp papers for0.33μm particle in the oil and0.26μm NaCl aerosol particle comes to99.958%-99.975%and99.964%-100%, respectively. The results demonstrate that beating degree has higher influence on pore volume than mass per square area.Compared filtration properties with commonly used automobile engine oil filtration materials, we know that different hemp papers have higher filtration efficiency of99.852%-99.975%and pressure drop, while the hemp weave fabric has the worst filtration efficiency of3.8%and the smallest pressure drop of6.87Pa.On the basis of same condition of cooking, bleaching, defibering process, the hemp paper of38°SR and70.49g/m2is used to pilot preparation and making automobile engine oil filter. Compared with standard oil filter, we know that the hemp paper oil filter has better filtration efficiency and formability, while there are still some problems should be solved in the future for practical application.(5) After analysis of the predecessors’ theory of pressure drop, it can be found that the materials and purposes of predecessors’ theory are different from this paper, moreover, there is no pressure theory of cleaning oil flowing through porous material. The hemp/cotton spunlaced nonwoven is used to make a deep comparison of pressure drop between theoretical value and experimental value, which indicates that there is an obvious difference between them, so it is necessary to set up our own pressure drop theory. Compared with experimental value of pressure drop, it can be demonstrated that the theoretical value of revised equation has a better fitting effect for different hemp papers and hemp/cotton spunalced nonwoven. Meanwhile, parameters of df=14.53μm,ω=84.99%, μ=1.275×10-2Pa-s and p=850kg/m3are used to simulate internal flow field of hemp/cotton spunlaced nonwoven in the case of2D model.