Design and optimization of truck cab tilting system


        There are two types of truck cab tilting systems, mechanical and hydraulic. The mechanical output torque is small, which is suitable for light trucks; the hydraulic output torque is large, which is suitable for heavy trucks. The design of hydraulic tilting system mostly relies on the engineering experience of technicians, and there is no complete design theory and method.

        The mechanical type is mainly composed of torsion bars, etc., which has the advantage of low cost, but the torsion bars are prone to stress concentration and lead to failure; the hydraulic type is mainly composed of oil cylinders, oil pumps, etc., and has the advantages of large output torque and high reliability.

        Heavy-duty truck cab tilting system, now choose hydraulic type. The hydraulic tilting system is designed from two aspects of mechanical structure and hydraulic circuit. In the mechanical structure design, the specific positions of the upper and lower fulcrums of the oil cabin tilt cylinder are selected according to the structural layout and possibility of the whole vehicle, and the hard connection between the oil cylinder and the cab is determined, and the stroke and turning angle of the oil cab cylinder, the oil volume of the oilcabin pump and the diameter of the piston are deduced.The quantitative relationship between the operating force of the oil pump and the diameter of the plunger, from which the stroke of the oil cylinder, the lifting force of the oil cylinder, the oil storage capacity of the oil pump and the operating force of the oil cab pump are calculated. In the hydraulic circuit design, the oil cylinder and the oil pump are used as the main components of the hydraulic circuit, and the turning process is divided into lifting and pulling back circuits for design. The lift circuit mainly supplies oil to the rodless chamber of the cylinder through the oil pump, the pressure difference between the two chambers of the cab tilt cylinder pushes the piston rod out and lifts the cab, the pull-back circuit supplies oil to the rod chamber of the cylinder through the oil cabin pump, and the pressure difference between the two chambers pushes the piston rod back Retract and pull back the cab; add a one-way throttle to the pullback circuit to prevent the cab from automatically dropping back.

        The mechanical structure and hydraulic system of the hydraulic turning system are modeled and simulated, and the turning angle, oil port pressure and piston rod displacement curve are obtained, and they are compared with the corresponding requirements to verify whether the design results meet the technical requirements. For the return vibration of the oil tilting cylinder, the ball diameter of the check valve was selected as the optimization analysis factor by using the DOE test design method, and the opening and closing process of the check valve was analyzed from the statics and dynamics. Quantitative relationship of valve line diameter. Further flipping, crawling and several performance tests were carried out, the flipping angle, oil port pressure and piston rod displacement curves were collected, and the test results were compared with the simulation results to verify whether the physical prototype meets the design requirements. According to the technical requirements of a heavy truck cab with a mass of 900kg and a flip angle of 55°, the design cylinder diameter is 59mm, the piston diameter is 30mm, the piston rod diameter is 38mm, the stroke is 348mm, the oil pump plunger diameter is 3mm, and the oil storage capacity is 308ml. The simulation results are that the flip angle is 55°, the oil port pressure is 27.8MPa, the displacement of the piston rod is 346.5mm, and the relative errors are 0.71% and 0.43%, respectively, which meet the design requirements. The test results are that the flip angle is 55°, the displacement of the piston rod is 348mm, which is in full agreement with the requirements, the oil port pressure is 27.9MPa, and the relative error is 0.36%, which meets the design requirements.