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What is the working principle of a torque converter?
Release date:
2022-07-07 10:41
Source:
Dana torque converter What is the working principle?
The solid housing of a torque converter contains four components: the turbine, the stator, the pump impeller, and transmission fluid. The operating principle of the torque converter is as follows: the pump impeller is driven by the engine to rotate, which in turn sets the fluid into motion, causing it to spin about its axis along with the impeller and thereby acquiring both velocity (kinetic energy) and pressure. The fluid’s velocity depends on the pump impeller’s radius and rotational speed. The stator redirects the flow of transmission fluid before it strikes the pump impeller again, thereby enhancing the converter’s efficiency. The stator features a highly sophisticated blade design that can completely reverse the direction of the fluid flow.
How to maintain it Dana torque converter ?
Common malfunctions of a torque converter include insufficient power output and excessive temperature. According to the torque converter’s characteristic curve, as the output torque—i.e., the turbine torque—varies with changes in external resistance, the output torque remains relatively high while the turbine speed decreases. When the output torque rises to a constant value, the turbine speed drops to zero, whereas the input torque to the converter stays unchanged, meaning the engine load remains constant. Consequently, when external resistance reaches a certain threshold, the converter’s output torque (turbine torque) attains its maximum value, the turbine speed falls to zero, and the vehicle’s speed also becomes zero. However, the engine does not emit black smoke, decelerate, or stall; it continues to transmit torque from the pump impeller to the converter. This phenomenon is known as “stall.” Under stall conditions, the converter’s transmission efficiency drops to zero, and all the kinetic energy supplied by the engine is converted into oil‑churning losses—essentially heat—thereby raising the converter’s oil temperature. Therefore, this situation must be avoided during operation. Within the range of turbine speed variations, the converter can still propel the vehicle at high speeds.
Efficiency hinges on a single factor. Hydrodynamic transmission can achieve continuously variable speed, but this is not guaranteed and must be operated within a specific range of turbine speeds; otherwise, transmission efficiency becomes very low. Consequently, when driving machinery with hydraulic transmission, gear ratios need to be adjusted according to varying load conditions. The engine throttle should be set near the rated speed—typically around 3,360 rpm—and prolonged operation in the low-efficiency zone not only wastes fuel and time but also leads to elevated oil temperatures. Normal practice involves increasing throttle input and shifting gears frequently, while closely monitoring the torque converter’s operating oil temperature and pressure. Installation accuracy during routine maintenance also affects the torque converter’s transmission efficiency. The pump impeller, housing, and turbine of a hydrodynamic torque converter are all high-speed rotating components; their static imbalance must not exceed 15 G·cm during manufacturing. Therefore, during service, avoid using screws of unequal lengths to connect the pump impeller and turbine, as this can disrupt their balance and result in power loss. Furthermore, end-face runout during operation of the pump impeller and turbine likewise impacts transmission efficiency. During production, the runout between the cover plate and the pump impeller connection surface should not exceed 60 µm, and the runout between the wheel bearing seat face, the turbine coupling disc face, and the torque converter housing–bearing seat connection faces should not exceed 20 µm. Accordingly, thorough inspection and meticulous cleaning of these mating surfaces are essential to prevent adverse effects on runout. If the torque converter operates for extended periods at elevated oil temperatures, the rubber seals will age, leak, or become damaged.
Dana torque converter
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