| In recent years, with the development of multi-functional construction vehicle, some construction vehicles will have both functions of on-site construction and material handling. For the vehicles with a certain speed and heavy-duty, people are raising higher and higher requirements to the security of its braking system. However, the previous studies to braking system of construction vehicle tend to focus on the single conventional braking system, and the studies to united braking system included conventional and auxiliary braking system are less. In fact, in the process of driving the vehicle, the conventional braking system is just used for emergency braking, most of the time the auxiliary braking system is used for vehicles’ decelerating and stopping. Therefore, when studying the conventional braking system of construction vehicles, adding auxiliary braking system and studying the united braking system have important significance to the security use of construction vehicles.Based on the school-enterprise cooperation project "Automatic Loading Mobile Concrete Mixer Development", this paper focuses on the study for full hydraulic united braking system of a certain vehicle. In this system the main braking system is full hydraulic braking system, and the auxiliary braking system is hydraulic feedback braking system which is caused by the closed hydraulic driving system based on the NFPE technology. This kind of braking system is widely used in the field of construction vehicles. It has a certain application value for some other vehicles to do some theoretical analysis, simulation studies and experimental tests to this braking system. The full text can be included in following aspects:Through extensive reading of relevant literature, this paper summarized the form and application status of conventional braking systems. Then through elaborating key technologies and research status of full hydraulic braking system, this paper listed the main contents.Through detailed description to the components and working principle, this paper summed up the working characteristics of subsystem and system, and proposed two working way especially to hydraulic feedback braking system. Then it summarized the working characteristics through using mathematical models to analyze the main constituent elements of two subsystems included accumulator, charging valve, hydraulic brake valve, driving pump and driving motor, which can reflect the performance of the system, and laid the theoretical foundation for the full text.Relying on AMESim simulation platform for the gradual establishment of elements model, subsystem model and system model, it set the system parameters according to the actual structure and carried out simulation analysis. For full hydraulic brake system, it analyzed the working characteristics of components, as well as charging characteristics and braking characteristics of system. For hydraulic feedback braking system, it verified the actual working principle during braking and took two measures to improve. To full hydraulic united braking system it set actual simulation conditions and proved the working characteristics of united braking process: During braking, the two kinds of brake system both had braking effect. The full hydraulic brake system is better, and they didn’t work at the same time.Taking an automatic loading mobile concrete mixer as experimental subjects, it designed experimental program for full hydraulic united braking system and tested a variety of experimental conditions. Experiments show that the performance of full hydraulic united braking system was in line with the results of simulation and theoretical analysis, and some small differences were due to the piping layout. Experimental process played a very good role in verifying the text before, and it proved that full hydraulic united braking system has a good dynamic performance. |
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