关键词: 商用车；机械式自动变速器；滑套；变速箱制动器

Abstract: Automaticed mechanical transmission (AMT) is a transmission device that can automatically shift gears according to the operating state of the vehicle and the road environment of the vehicle. The AMT commonly used in commercial vehicles isshifting powered by compressed air, and the transmission control unit (TCU) controls the solenoid valve according to the software logic to realize the disengage and engage of the clutch and the gearshifting of the gearbox. The synchronization process of commercial vehicle AMT shift is automatically completed by the gearbox, and the mainstream commercial vehicle AMT at home and abroad adopts the dog clutch structure with simpler structure, lower cost and more reliable quality. Compared to synchronizers, the dog clutch structure requires a transmission brake (TB) to synchronize the process during upshift. This paper analyzes the factors affecting the performance of AMT TB, and designs a specific experimental test method to test the effects of each factor on the performance of TB on the experimental test bench. The test result has shown that the diameter of TB friction plates affects the braking rate, and the larger the diameter, the greater the braking rate; The number of TB friction pads has an impact on response time and braking rate. The more the number, the faster the response time and the greater the braking rate; The TB airway diameter affects the response and exit time, and the larger the airway diameter, the faster the response and exit time; The air source pressure affects the braking rate of TB, and the greater the pressure, the greater the braking rate. The conclusions of this paper provide support for the design and calibration work of AMT TB on commercial vehicle

Key words: commercial vehicle; AMT; dog clutch; transmission brake