In recent years, with the booming development of the domestic automobile market, the number of cars in China has been steadily increasing, but the incidence of traffic accidents is also constantly increasing, with rear end collisions accounting for about 20%. When a car experiences a rear end collision during driving, the driver and passengers who are hit will have a significant instantaneous impact on the seat and headrest under the action of inertia. If the seat fails to lock, the driver and passengers will instantly tilt back, which may cause harm to the human body. Different backrest angles also have different degrees of physical injury to passengers. Therefore, to ensure the safety of drivers and passengers, car and seat manufacturers usually conduct strict strength performance tests to ensure that seat adjusters have good locking function.
Automatic transmission can automatically judge and select the appropriate transmission ratio based on the actual state of the vehicle transmission system itself and the outside world, combined with driving conditions, without reducing the effective power of the vehicle, and control its power system to always operate around the optimal efficiency point. At the same time, it can also eliminate the influence of different personnel operating habits on the overall vehicle control, not only reducing the driver’s workload, but also improving the reliability of vehicle driving.
This type of wheeled armored vehicle uses an electronically controlled hydraulic multi-stage bevel gear AMT with a single box two axis structure. The driving gear and the driven gear of each gear are in a constant meshing state. External power input is transmitted through the driving shaft and driving gear of the automatic transmission, driving the driven gear to rotate. The driven gears of each gear float on the driven shaft through double row needle roller bearings. Each driven gear corresponds to a driven shaft with a connecting key block arranged in the circumferential direction. When a gear key block connects the driven shaft and the driven gear into one, power can be transmitted from the driven gear of that gear to the driven shaft, After being transmitted through a normally meshed gear pair, it is output.
By analyzing and calculating the system composition structure and working principle of the hydraulic multi-stage bevel gear AMT, the overall structure and specific dimensions of each transmission component were determined. Through finite element simulation, overall modal analysis, and multi-body dynamics simulation, the designed hydraulic multi-stage bevel gear AMT meets the requirements of torque transmission, with reasonable structural dimensions and relevant parameter analysis and output characteristics consistent with theory. Based on the calculation and analysis results, the machining of the main components of the hydraulic multi-stage bevel gear AMT and the assembly and debugging of the entire machine have been completed, including some components and the overall prototype.
The hydraulic multi-stage bevel gear AMT test platform mainly consists of three parts: mechanical system, control system, and software system. The mechanical system structure diagram of the new AMT test platform in this article shows that the hydraulic multi-stage bevel gear AMT is installed between the drive servo motor and the torque sensor. The power input characteristics of the engine are simulated by controlling the drive motor. The inertia load of the automatic transmission during actual driving is simulated through the inertia disk, and the load characteristics during actual driving are simulated through the magnetic powder brake. Analysis shows that the output speed of the hydraulic multi-stage bevel gear AMT prototype in this article follows an orderly pattern and operates relatively smoothly. The actual transmission ratio is calculated by the ratio of the input speed to the output speed obtained from the experiment. The maximum error between the actual transmission ratio mean and the theoretical calculation value occurs in the first gear, with an error value of 0.111 and an error rate of 3.69%, which is within the normal range. Therefore, according to the experimental results, it can be seen that under no-load conditions with a single speed input, the transmission ratio obtained from the experiment has good consistency with the theoretical calculation value.
The transmission characteristics of the prototype were experimentally studied under different gear positions, input speeds, and load conditions. The results showed that the hydraulic multi-stage bevel gear AMT prototype had good transmission stability, and the influence of speed and load size on the transmission ratio was small. The maximum error between the measured transmission ratio and the theoretically calculated value was 0.11, with a maximum error rate of 3.7%, indicating good consistency.