Abstract: In recent years, China's automobile industry has developed rapidly, with the design level and production continuously improving. The assembly design and process of automobile water pump bearings affect the bearing life, reasonably reduce costs, and improve the stability of the entire vehicle. This article conducts research on the assembly design and process of automotive water pump bearings, and proposes several improvement suggestions.
Keywords: Automotive water pump; Bearings; Assembly design; workmanship
0 Introduction
The development of China's automotive industry is rapid, and the requirements for production and quality are gradually increasing. At the same time, the design and process requirements for automotive water pump bearings are also constantly improving. In the design process of automotive water pump bearings in China, imitation is mainly used, and there is no unified assembly design standard, resulting in significant differences in internal structure. Pay attention to the assembly design and process improvement of automotive water pump bearings, scientifically construct internal structures, strengthen parameter control of strength, temperature, and service life, improve load-bearing capacity, reduce friction phenomena, reasonably reduce costs, be good at using press machines for assembly, and design reasonable fixtures to achieve bearing installation. The assembly design and process of automotive water pump bearings are the key to reasonably extending the service life of bearings, providing reliable power for the cooling system of automobiles and improving the stability of the entire vehicle.
1 The importance of assembly design and process research for automotive water pump bearings
In recent years, China's automotive industry has made great efforts to develop towards high-power and high power, which has put forward new requirements for automotive water pump bearings. They need to have high characteristics such as heat resistance, sealing, and long service life. Reasonable assembly design and process application can provide reliable guarantees for system operation. With the application of new structures, the shaft connected bearing structure is gradually being widely used, and should be widely adopted in countries such as the United States, Germany, and Japan. In recent years, China has also attached importance to its standardized development and research, providing a reliable foundation for the assembly design and process improvement of automotive water pump bearings. By using water pump bearings, the problem of rapid engine temperature rise caused by fuel combustion and energy driven crankshaft and connecting rod mechanism movement can be reduced, ensuring effective control of mechanical and wear issues of internal parts of the engine and ensuring normal engine operation. The water pump provides reliable power for the cooling system of the car, and drives the impeller to rotate through bearings to obtain pressure and speed for the coolant, realizing the transportation of the cooling system flow channel and ensuring the effective operation of the system. The pump body, impeller, bearings, water seals, and pulleys make up the automotive water pump. Faced with harsh environments such as high temperature and humidity during operation, the assembly design and process requirements of the water pump are higher. As a precision mechanical component, in the assembly and process flow, attention is paid to the management of bearings and surrounding parts, and the replacement of mechanical processing scars, burrs, and other issues. During the installation process, more precise tools must be used to ensure the consistency of the main shaft and inner hole, and to ensure the healthy operation of the automotive water pump.
2 Assembly Design of Automobile Water Pump Bearings
2.1 Performance analysis of water pump bearings
The structure of automotive water pumps is relatively compact, and their working environment is harsh, which requires high stability and service life of the equipment. Especially in the assembly design process, it must be combined with reality to ensure that the water pump bearings are in a Z-optimal operating state, reduce friction losses, temperature rise and other issues, and reasonably improve the service life of the bearings. The car cold water pump is composed of a shell, a pulley, bearings, a water seal, an impeller, a cooling fan, and other transmission components. During operation, one end of the bearing is subjected to radial force generated by the rotation of the belt, while the other end is subjected to unbalanced force generated by the rotation of the impeller. As a non-standard shaft, the water pump bearing has good assembly performance and can meet operational needs, reduce clearance adjustment space, and achieve the operation of the entire vehicle cooling system. During the operation of the car water pump, the speed of the water pump is high, and the bearings need to have high bearing capacity to prevent problems such as centrifugal force caused by eccentric mass of the coupling and cooling water entering the mechanical seal ring. During operation, the space of the water pump is relatively limited, and there is a lot of operating temperature, humidity, and dust. To ensure the durability of the seal, the bearings need to operate under harsh conditions. During the assembly process, a high-precision press and press process are also required to provide reliable support for bearing assembly.
2.2 Pay attention to the assembly design of water pump bearings for bearing capacity
Due to limited internal space, the distance control of the water pump bearing structure is mainly based on the rolling inspection of two rows of rollers and balls. In the structure of automotive water pumps, grooves are made on the inner shaft of the bearings. In the design process, attention should be paid to the bearing life. The rated dynamic load and equivalent are calculated separately on the ball and roller rows to ensure the durability requirements during operation. The technology of shaft connected bearings in automotive water pump bearings has been standardized and promoted abroad. Relevant enterprises in China also pay attention to this information, timely develop different products, actively introduce products and technologies in the assembly design process, reasonably improve the cost control ability of design and development, focus on extending the bearing life, and ensure the effective operation of the system. In automotive water pump bearings, the structure of one row of rollers and one row of balls is suitable for situations with larger radial load coefficients. Currently, the double row ball structure is mainly suitable for systems with smaller radial load coefficients. The outer diameter size of the bearing, the loading position of the pulley, and the distance between the two rows of balls affect the bearing capacity. During the driving process of a car, the cooling water is generally maintained between 60-80 degrees. The water pump bearing is mainly composed of axial force and rotational resistance moment generated by the fan rotation. The pulley has belt tension, and the water pump impeller generates axial force, radial force, and rotational resistance moment. The radial and axial reaction forces of the two rows of rollers have weight on each component, which affects the bearing capacity of the car water pump shaft. In the design process, relevant content must be considered, and based on different force calculations, the required bearing capacity of the water pump bearing should be formulated to ensure the stable service life of the water pump bearing.
2.3 Strengthen the design of sealing rings for automotive water pump bearings
In the assembly design of automotive water pump bearings, the sealing ring design of the water pump should also be considered. The structure of the automotive water pump should prevent water and oil from seeping in, reducing the system life. The sealing ring of water pump bearings is generally made of a metal skeleton to increase the rigidity of the structure, with rubber as the main body of the sealing ring, strengthen the fit with the outer ring teeth, and adopt a reasonable sealing structure to ensure the occurrence of grease leakage and water entering the bearing cavity in the water environment. The reasonable control of the interference between the shaft and the seal is insufficient, resulting in friction heat generation and insufficient sealing. In addition, there are micro convex problems on the bearing surface. In assembly design, attention must be paid to the fatigue of the contact surface between the shaft and the sealing ring, and the periodic alternating stress and its distribution on the contact surface should be reasonably formulated. Combined with fatigue life theory, the effective life of the bearing sealing ring should be extended.
3 Assembly process of automotive water pump bearings
The assembly process of automotive water pump bearings is one of the main factors affecting the bearing life cycle. Through years of research and development, the assembly process of bearings has been continuously improved, and the application of press machines has gradually become mainstream. The precision of press machines has been continuously improved to ensure the balanced operation of bearings. In the assembly process of bearings, it is necessary to keep the axial centerline consistent with the assembly hole. Once the bearing assembly is unbalanced, it can cause the load on the steel ball due to the tilting of the press fit, which can easily lead to deviation of the raceway trajectory, increased stress on the grease mixing and retainer, resulting in high bearing temperature and increased equivalent load on the steel ball, all of which have an impact on the service life of the bearing. In the interference fit between the water pump bearings and the pump body, a press is used for pressing. There are generally two types of presses, hydraulic and pneumatic, and pressure monitoring equipment is equipped. An alarm will be triggered if the pile pressing process exceeds the set range, and problems such as excessive pressing, tilting of the bearings during pressing, and other issues can be timely grasped. However, due to the large pressure range, precision controllability cannot be achieved, which can easily cause deviations and is not easy to detect. As a precision component, the water pump shaft bearing must be inspected for quality issues such as machining marks, burrs, and cutting between the casing, flange, impeller, and water seal in the equipment to prevent installation force from acting on the rolling ball during installation. Mechanical pressure should be reasonably used for pressing, and auxiliary tools should be used to adjust the consistency between the inner hole and the main shaft to ensure functional coordination. The interference fit between the water pump bearing and flange should be designed and installed reasonably to meet the load-bearing and strength requirements of the structure, reduce the phenomenon of excessive stress concentration at the edges of the contact area, and set a reasonable interference fit. Methods such as chamfering or arcing can be used at stress concentration points to improve the strength of the structure and ensure operational requirements.
Before installing the bearing, it is necessary to check the mating surface, grooves, and machining quality of the connecting surface between the shaft and the casing. The mating connecting surface must be cleaned as necessary and installed in a dry and clean environment. The selection of lubricating oil for bearings should also be emphasized. Lubricating grease with good performance such as impurity free, antioxidant, and rust prevention should be selected, and a reasonable filling amount should be filled into the bearing. The lubricating grease already filled for double row roller bearings with sealing structures and water pump shaft connecting bearings cannot be cleaned and can be used directly.
In the assembly process of automotive water pump bearings, bearing pressing is the key point of design. Reasonable use of pressing technology ensures the force balance of the bearings, reduces friction, and reasonably improves the service life of the bearings. The design lifespan of automotive water pump bearings is required to be over 5000 hours. Before pressing the bearings, the pump body needs to be heated to 100 degrees Celsius to meet the increased demand for thermal expansion in the shaft hole. To increase the pulling force of the bearings, the adhesive coating method can be used to reduce the pressing force. If the pump body wall thickness is prone to shell deformation and fracturing, the bearing hole wall can be used as a support to facilitate pressing and debugging, strengthen the precision and pressure accuracy of pressing, ensure accurate positioning of pressing depth, strength, and pressure within the required range. Pay attention to the parameter setting of the pressing machine, ensure correct pressing data, avoid deviations during testing, improve the effectiveness of the pressing machine, and provide reliable guarantee for the operation of bearings. During the pressing process, fixture guidance can be used, and attention should be paid to the distance between the pressing guide sleeve and the positioning block to prevent excessive or insufficient coaxiality, matching the clearance between the guide sleeve and the inner shaft of the bearing with the length of the bearing, and preventing tilting of the pressing and wear of the steel ball. The pressure, speed, and time of the pressing should be deeply controlled, and the positioning and guiding accuracy of the bearing should be emphasized. After installation, a rotation test should be carried out using power for no-load or low-speed operation. If there are no abnormalities, the rotation speed and load should be slowly increased according to the operating conditions. The generated noise, vibration, and temperature rise should be monitored. If any abnormalities occur, the operation should be stopped immediately and checked before normal use can be carried out.
4 End
The assembly design and process of automotive water pump bearings involve the service life of the bearings, providing reliable guarantees for the automotive cooling system. In the assembly design, attention is paid to the bearing's bearing capacity and sealing design to ensure the effectiveness of operation. In the assembly process, emphasis is placed on the control of the pressing process to ensure the balanced assembly of the shaft and assembly hole, and to provide guarantees for the operation of the steel ball. In the current era of continuous improvement in automotive technology, the water pump, as the key to the cooling system, plays a role in stabilizing and extending the engine. As a weak link in the water pump, bearings not only need to be improved in the design process, but also need to improve their lifespan and durability from the perspective of process methods, achieving the healthy and stable operation of water pump bearings and providing reliable guarantees for the cooling system. With the continuous development of China's automotive industry, reasonable assembly design and process improvement have effectively extended the service life of automotive water pump bearings. In the structural design process, emphasis is placed on the scientificity of various parameters, and the installation accuracy is improved in terms of technology, providing reliable guarantees for the operation of cooling systems, maintaining the smooth operation of automotive engines, and providing reliable guarantees for the development of the industry.
2024 April 4th Week VAFEM Product Recommendation:
Water pump bearings are double row bearings and, in contrast to conventional double row bearings, do not have an inner ring but raceways machined directly into the surface of the shaft.
As a precious high quality water pump bearings manufacturer and supplier in China, VAFEM can guarantee the quality and precision of the products through complete testing technology and advanced equipment. Please come to buy water pump bearings at the best price and quality from VAFEM. Please contact us for any questions!
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2024-04-28