The "turbine" in the torque converter is fixed to the output shaft by the internal spline and the "locking clutch", and the power is output to the gear box.
Focus on this issue and understand why the turbine is locked with the lockup clutch. Why do I need a lockup clutch? Is there a free running part in the torque converter? And what is the meaning of the guide wheel? It is necessary to start with the purpose and structure of the torque converter.
The main purpose of using a torque converter is:
Through the flow of oil, the flexible transmission of torque, and a small range of variable torque. It is used in most automatic models to make the vehicle more compliant when starting and shifting, and to initially amplify the engine torque.
The main structure of the torque converter:
The inside of the torque converter is composed of "pump wheel", "turbine", "guide wheel (fixed impeller)" and "locking clutch", and the inside is filled with hydraulic oil as a force transmitting medium.
The "pump wheel" is affixed to the torque converter housing and is connected to the input shaft.
The "turbo" and "lockup clutch" are connected together with the output shaft.
The "guide wheel" is sandwiched between the pump wheel and the turbine and is fixed to the casing by a one-way clutch.
The working principle of the torque converter:
After the power is output from the engine flywheel, the pump wheel connected to the torque converter housing is driven, and the pump wheel agitates the internal hydraulic oil, and the oil rushes toward the turbine along the pump wheel casing under the centrifugal action, and pushes the turbine to rotate and then flows. The position of the shaft center passes through the guide wheel to the direction of the oil flow, and returns to the pump wheel again and again, and the power is transmitted to the gear box through the output shaft connected to the turbine.
The role of "guide wheel":
If there are only pump impellers and turbines in the structure, the entire mechanism will lose its torque and become a simple coupler. After the guide wheel is added, the hydraulic oil flows from the turbine into the fixed non-rotating guide wheel, and the direction changes, so that the flow direction is consistent with the rotation direction of the pump wheel, which enhances the rotation torque of the pump wheel, thereby increasing the output torque. Make the entire mechanism have a torque function.
Free moving parts in the torque converter:
When the pump wheel and the turbine speed are basically the same, the guide wheel completes its work. At this time, if the guide wheel continues to be fixed and does not rotate, the oil will impact the back of the guide wheel, causing loss of output torque, so the fixed guide wheel is fixed at this time. When the one-way clutch fails, the guide wheel will rotate freely with the oil in the same direction.
The role of the "locking clutch":
Although the torque converter has a torque converter, the transmission efficiency will change with the change of the speed ratio between the turbine and the pump wheel. When the speed ratio reaches 80% (the pump wheel and the turbine are basically synchronized), the transmission of the torque converter The efficiency will drop suddenly, when the lock-up clutch will work, the output shaft is hard-wired to the torque converter housing, and the transmission efficiency is maximized, which is suitable for the vehicle to be in cruise or gentle acceleration conditions.
