With the debut of the automatic transmission system, vehicles were changed forever. With new components, shifting gears and general operation became much more simple as many functions began to be automatically controlled by the transmission system. One of the new additions to the automatic transmission, the torque converter, is a very important system component that replaced the clutch.
Torque converters are a type of fluid coupling, and they are what allows for an automobile engine to continue running while the wheels are stationary, among other important functions. In this blog, we will discuss what the torque converter is, as well as how they function.
Within the assembly of a vehicle, the torque converter is located in between the transmission and the flexplate of the engine, connecting the power source to the load. Typically, torque converters are composed of three different parts, those being the impeller, turbine, and stator.
The
impeller, or pump, is a component that spins with the engine crankshaft and is filled with fluid. As the angular velocity of the impeller increases, so too does the force of the fluids within it. The fluids within the impeller are then sent into the turbine, which is an assembly of blades.
The blades of the turbine rotate as fluids enter the component, and fluids flow from the outer section to the inner section repeatedly and are then sent back to the impeller, forming a fluid coupling. The stator of torque converters serves to transfer fluids back into the impeller, thus slowing them. The stator features a number of fins that reverse the direction of the fluid back into the impeller.
During operation, the torque converter conducts three operations including acceleration, stall, and coupling. When a driver of a vehicle steps on the gas pedal, the impeller begins to increase speed of rotation. As the impeller reaches an angular velocity that exceeds the turbine, torque is generated which helps in vehicle acceleration. When the vehicle needs to stop, such as at a stoplight, the stator breaks the hydrodynamic circuit, allowing the transmission to operate independently from the engine.
This allows for the vehicle to come to stop without causing a stall in the engine. The last
function of torque converter is during cruising speeds, in which the converter acts as a coupling bearing. This is due to the fact that when cruising, the impeller and turbine rotate with the same angular velocity, thus no torque is being generated. A lockup clutch then locks the turbine to the impeller, ensuring no power loss so that the car moves smoothly.
Due to the many important functions that are provided by the torque converter, it is important that they are kept well maintained and replaced as necessary. Oftentimes, a suspected transmission problem may just be the fault of the torque converter, rather than the system as a whole. Common signs of failing torque converters include the shuddering of a car at speeds between 35-45 mph, increased stall speeds, overheating, or slipping of gears.