As a key supporting structure of the urea pump upper and lower aluminum plates of the automotive urea pump are susceptible to thermal deformation, directly impacting the pump's sealing performance, metering accuracy, and overall reliability. In diesel engine exhaust aftertreatment systems, the urea pump operates continuously under high temperature and high-frequency vibration. Due to its high coefficient of thermal expansion, the aluminum plate is prone to deformation caused by localized temperature gradients or structural stress concentration, leading to urea solution leakage, pump wear, or injection deviation. Reducing the risk of thermal deformation through structural design optimization requires a comprehensive approach considering material properties, structural topology, and thermal management.
The material properties of the aluminum plates in the urea pump upper and lower aluminum plates are a fundamental factor influencing thermal deformation. While aluminum alloys offer lightweight advantages, their coefficient of thermal expansion is approximately twice that of steel, making them prone to significant deformation under temperature fluctuations. Optimized design should prioritize alloys with low coefficients of thermal expansion, such as 6061-T6 or 7075-T6. These materials can have their resistance to thermal deformation significantly improved through solution strengthening and aging treatments. Meanwhile, surface treatment processes can further improve material properties. For example, anodizing can form a dense oxide film on the aluminum plate surface, which not only improves corrosion resistance but also constrains substrate expansion and reduces deformation through film hardness. Furthermore, localized material strengthening techniques, such as laser shock peening or shot peening, can introduce residual compressive stress in critical areas of the aluminum plate, offsetting tensile deformation caused by thermal stress and improving structural fatigue resistance.
Structural topology optimization is a core method for reducing the risk of thermal deformation. Traditional aluminum plate designs often employ flat plate structures of uniform thickness. However, during urea pump operation, the upper and lower aluminum plates of the urea pump are in contact with the pump body, support, and high-temperature exhaust pipe, resulting in a significant temperature gradient. Uniform thickness design easily leads to excessive expansion in areas of concentrated heat, causing plate warping. Through topology optimization technology, the stress distribution of the aluminum plate under a thermo-mechanical coupling field can be simulated based on finite element analysis (FEA), identifying high-stress areas and adding targeted reinforcing ribs. For example, designing annular reinforcing ribs around the urea pump mounting holes can improve local stiffness and disperse heat through the thermal conductivity of the ribs, reducing temperature gradients. A gradient thickness structure can be designed at the edges of the aluminum plate, appropriately increasing the thickness in high-temperature zones and decreasing the thickness in low-temperature zones, thus balancing thermal expansion through mass redistribution. Furthermore, using biomimetic structures, such as hexagonal grid reinforcing ribs mimicking a honeycomb, can significantly reduce the risk of deformation while ensuring lightweight design and dispersing stress through multi-directional support.
Thermal management design is an important supplement to structural optimization. During urea pump operation, the surface temperature of the aluminum plate may exceed 80°C, while the ambient temperature may drop to -40°C. This extreme temperature difference can exacerbate thermal deformation. Optimized design needs to address both heat dissipation and insulation: for heat dissipation, microchannel structures can be designed on the aluminum plate surface to carry away heat through fluid circulation (such as coolant or air), reducing the plate surface temperature; or high thermal conductivity materials (such as copper-based composites) can be locally embedded in the aluminum plate to form efficient heat conduction paths and reduce heat accumulation. For thermal insulation, a ceramic fiber insulation layer can be added between the aluminum plate and the high-temperature source (such as an exhaust pipe) to block heat conduction; alternatively, a polyimide film with low thermal conductivity can be used to cover the surface of the aluminum plate to reduce radiative heat transfer efficiency. Through thermal-structural coupling simulation verification, the optimized aluminum plate can reduce the temperature fluctuation range by more than 30% and the thermal deformation by 50% under the same operating conditions.
Improved assembly processes can also indirectly reduce the risk of thermal deformation. The connection method between the aluminum plate and the urea pump body and bracket directly affects the stress transmission path. Traditional bolted connections are prone to loosening due to differences in thermal expansion coefficients, leading to loosening or deformation. Optimized designs can use elastic connectors, such as wave spring washers or rubber shock absorbers, to absorb thermal stress through elastic deformation, avoiding stress concentration caused by rigid connections. Furthermore, using low-heat-input welding processes such as laser welding or friction stir welding can reduce the heat-affected zone, lower the risk of local material performance degradation, and improve the overall structural stability.
By comprehensively applying material selection, structural topology optimization, thermal management design, and assembly process improvements, the risk of thermal deformation of the upper and lower aluminum plates of the urea pump in automotive components can be significantly reduced. The optimized aluminum plates not only meet the reliability requirements of the urea pump under high temperature and high frequency vibration environments, but also improve the fuel economy of the entire vehicle through lightweight design, ensuring the long-term stable operation of the diesel engine exhaust aftertreatment system.
