Abstract: This application provides a two-speed transmission system. The two-speed transmission system includes a first fixed gear fastened on a first shaft, a first floating gear connected to a second shaft through rotation, a first connection mechanism, and a one-way clutch. The first connection mechanism is configured to implement connection or disconnection between the first floating gear and the second shaft. The one-way clutch is located between the first floating gear and the first connection mechanism. An inner surface of the one-way clutch is connected to the first floating gear. An outer surface of the one-way clutch abuts against the first connection mechanism. The outer surface of the one-way clutch is connected to the first connection mechanism. An acting force of the outer surface directly acts on the first connection mechanism instead of a tooth surface of the first floating gear, to reduce an impact on accuracy of gear transmission.

Abstract: A gear shifting mechanism includes a drive motor, a shifting drum, and a first shifting mechanism. The first shifting mechanism includes a first shifting fork, an inner shaft, an outer hub, a first coupling pin, and an elastic component. The elastic component is sleeved on the inner shaft and is located between the inner shaft and the outer hub. There is a first limiting portion and a second limiting portion between the outer hub and the inner shaft. The elastic component is located between the first limiting portion and the second limiting portion. The first limiting portion is connected to one of the outer hub and the inner shaft, and the second limiting portion is connected to the other of the outer hub and the inner shaft.

Abstract: A motor shaft, a motor, and an electric vehicle. The motor shaft includes a shaft body and an insulation coating. The shaft body includes a first mounting portion and a second mounting portion that are connected by fastening. A positioning step surface is disposed at an end that is of the first mounting portion and that is close to the second mounting portion. The first mounting portion is configured to mount a rotor. The second mounting portion is covered with the insulation coating, and the second mounting portion is configured to mount a bearing. A resistivity of the insulation coating is not less than 107 ?·m. In this way, a possibility that a shaft current is generated when a shaft voltage discharges and breaks down a lubricating oil film in the bearing to form a path can be effectively reduced.

Abstract: This application provides a gear shifting mechanism, a gearbox, and a powertrain. The gear shifting mechanism includes a gear, a gear hub, a one-way clutch, and a sliding apparatus. The gear has a first convex wall and a second convex wall that are disposed around a shaft hole. A first toothed structure is disposed at an end of the first convex wall, and a diameter of the second convex wall is less than that of the first convex wall. The gear hub is sleeved on the second convex wall. The one-way clutch is disposed between the gear hub and the second convex wall. The sliding apparatus is sleeved on the gear hub, and the sliding apparatus is capable of sliding in a direction toward or away from the gear. The gear shifting mechanism can improve stability for transmitting a gear shifting power, thereby improving driving performance of an electric vehicle.

Abstract: A drive motor and a retarder in a powertrain meet a condition that a harmonic order of the drive motor is the same as a quantity of gear teeth of an input shaft gear in the retarder such that a frequency of an electromagnetic noise harmonic generated by the drive motor is the same as a frequency of a noise harmonic generated by the retarder. When the drive motor and the retarder are coupled using a connection structure, a phase of the electromagnetic noise harmonic generated by the drive motor differs from a phase of the noise harmonic generated by the retarder by a set angle.

Abstract: An electric vehicle drive system and an electric vehicle. The electric vehicle drive system includes a powertrain and a transmission system. The powertrain includes a first power output mechanism and a second power output mechanism. One end of the transmission system is connected to the first power output mechanism, and the other end is configured to be connected to an air-conditioner compressor. The second power output mechanism is configured to drive the electric vehicle to travel. The powertrain in the electric vehicle drive system can also drive the air-conditioner compressor when driving the electric vehicle, to reduce a quantity of components inside the electric vehicle, thereby reducing space occupancy and costs.

Abstract: This application provides a two-speed transmission system. The two-speed transmission system includes a first fixed gear fastened on a first shaft, a first floating gear connected to a second shaft through rotation, a first connection mechanism, and a one-way clutch. The first connection mechanism is configured to implement connection or disconnection between the first floating gear and the second shaft. The one-way clutch is located between the first floating gear and the first connection mechanism. An inner surface of the one-way clutch is connected to the first floating gear. An outer surface of the one-way clutch abuts against the first connection mechanism. The outer surface of the one-way clutch is connected to the first connection mechanism. An acting force of the outer surface directly acts on the first connection mechanism instead of a tooth surface of the first floating gear, to reduce an impact on accuracy of gear transmission.

Abstract: This application provides a gear shifting mechanism, a two-speed gearbox, and a vehicle. The gear shifting mechanism includes a drive motor, a shifting drum, and a first shifting mechanism. The first shifting mechanism includes a first shifting fork, an inner shaft, an outer hub, a first coupling pin, and an elastic component. The elastic component is sleeved on the inner shaft and is located between the inner shaft and the outer hub. There are a first limiting portion and a second limiting portion between the outer hub and the inner shaft. The elastic component is located between the first limiting portion and the second limiting portion. The first limiting portion is connected to one of the outer hub and the inner shaft, and the second limiting portion is connected to the other of the outer hub and the inner shaft.

Abstract: This application provides a gear shifting mechanism, a gearbox, and a powertrain. The gear shifting mechanism includes a gear, a gear hub, a one-way clutch, and a sliding apparatus. The gear has a first convex wall and a second convex wall that are disposed around a shaft hole. A first toothed structure is disposed at an end of the first convex wall, and a diameter of the second convex wall is less than that of the first convex wall. The gear hub is sleeved on the second convex wall. The one-way clutch is disposed between the gear hub and the second convex wall. The sliding apparatus is sleeved on the gear hub, and the sliding apparatus is capable of sliding in a direction toward or away from the gear. The gear shifting mechanism can improve stability for transmitting a gear shifting power, thereby improving driving performance of an electric vehicle.

Abstract: A method for monitoring chatter in a machining process includes the following steps: collecting an original signal related to chatter in the machining process; for the original signal, obtaining a signal segment for calculation and analysis by updating data points in a sliding window with a set step-length, where the step-length refers to a number of data points updated every time in the sliding window, and is not greater than the size of the sliding window; calculating fractal dimensions of the signal segments in the sliding window by using a fractal algorithm; and comparing the calculated fractal dimension with an identification threshold to determine whether chatter occurs in the machining process. The measured signal does not need to be preprocessed by using the method, which can greatly improve calculation efficiency and can ensure accuracy of chatter identification.

Abstract: A method for monitoring chatter in a machining process includes the following steps: collecting an original signal related to chatter in the machining process; for the original signal, obtaining a signal segment for calculation and analysis by updating data points in a sliding window with a set step-length, where the step-length refers to a number of data points updated every time in the sliding window, and is not greater than the size of the sliding window; calculating fractal dimensions of the signal segments in the sliding window by using a fractal algorithm; and comparing the calculated fractal dimension with an identification threshold to determine whether chatter occurs in the machining process. The measured signal does not need to be preprocessed by using the method, which can greatly improve calculation efficiency and can ensure accuracy of chatter identification.