If you ’re intimate withmanual transmittal , you make out that anengineis colligate to a contagion by way of aclutch . Without this connection , a railway car would not be able to come to a complete plosive speech sound without killing the engine . Cars with automatic transmissions have no clutch that disconnects the transmission from the engine . Instead , theyuse a devicecalled atorque converter . It may not look like much , but there are some very interesting thing going on inside .
Turning a car ’s engine crankshaft grow torsion ( which is the energy you make by twisting something ) . Torque is what permit you to accelerate your car . The more torque an engine give rise , the faster a railroad car belong . A torsion convertor allow the engine in a cable car with an robotic infection to keep run even as the wheel hail to a stop .
In this article , we ’ll see whyautomatic transmissioncars need a torque converter , how a torsion converter work as well as some of its benefits and shortcomings . The machinelike gearboxes we refer to are the traditional case that have been popular in car since about the fifties . new case of automatize infection , like thesemi - manual gearboxandCVTuse other method acting of power delivery , and do n’t let in torque converters .
Torque Converter Basics
A torque converter is a eccentric offluid mating , which allows the engine to spin somewhat severally of the transmission . If the engine is ferment slowly , such as when the car is idling at a traffic light , the amount of torque passed through the torsion converter is very small , so keeping the car still requires only a light insistency on thebrake foot lever .
If you were to step on the gasoline treadle while the car is stopped , you would have topress hard on the braketo keep the machine from moving . This is because when you step on the petrol , the engine speeds up and pump more fluid into the torsion converter , stimulate more torque to be transmitted to the steering wheel .
Inside a Torque Converter
There arefour componentsinside the very strong housing of the torsion converter :
The housing of the torsion converter is bolted to the flywheel of the engine , so it turns at whatever speed the engine is running at . The fins that make up the pump of the torque convertor are bind to the housing , so they also turn at the same speed as the engine . The cutaway below indicate how everything is connected inside the torsion convertor .
Theimpellerinside a torque convertor is a type of centrifugal pump . As it spin , fluid is flung to the exterior , much as the twist cycle of awashing machineflings H2O and apparel to the exterior of the dry wash tub . As fluid is chuck out to the exterior , a vacuum is created that draws more fluid in at the center .
The fluid then enters the blades of theturbine , which is connect to the transmission . The turbine have the transmission to birl , sending might through shafts , differential , and out to the driving wheel . you may see in the graphic at allow that the blades of the turbine are veer . This means that the fluid , which inscribe the turbine from the exterior , has to switch counselling before it exits the center of the turbine . It is this directional modification that induce the turbine to reel .
to shift the direction of a moving aim , you must practice a force to that aim — it does n’t weigh if the object is a car or a drop of fluid . And whatever applies the force that stimulate the aim to sprain must also feel that force-out , but in the diametric way . So , as the turbine causes the fluid to change direction , the fluid causes the turbine to spin .
The fluid exits the turbine at the center , moving in a different direction than when it accede . The fluid exits the turbine motivate opposite the direction that the pump ( and engine ) are turn . If the fluid were permit to hit the pump , it would slow the engine down , blow world power . This is why a torque convertor has astator .
We ’ll take a closer look at the stator coil in the next section .
The Stator
The statorresides in the very center of the torsion converter . Its job is to airt the fluid returning from the turbine before it collide with the pump again . This dramatically increases the efficiency of the torque convertor .
The stator has a very aggressive blade excogitation that almost whole reverses the guidance of the fluid . A one - room batch ( inside the stator ) unite the stator to a limit shaft in the transmission ( the direction that the grip earmark the stator to spin is noted in the figure above ) . Because of this arrangement , the stator can not spin with the fluid — it can spin only in the diametric guidance , force the fluid to change direction as it hits the stator blade .
Something a little spot tricky befall when the car gets moving . At main road focal ratio , both the impeller and the turbine are spinning at almost the same rate ( the pump always spins slightly faster ) . At this point , the fluid restoration from the turbine , entering the heart already moving in the same direction as the pump , so the stator coil is not needed .
Even though the turbine changes the charge of the fluid and flings it out the back , the fluid still ends up moving in the direction that the turbine is spin because the turbine is spinning faster in one direction than the fluid is being pumped in the other direction . If you were standing in the back of a cartridge move at 60 miles per hour ( 96 kph ) , and you threw a egg out the back of that pickup truck at 40 mph ( 64 kph ) , the ball would still be going onward at 20 mph ( 32 kilometers per hour ) . This is interchangeable to what happen in the turbine : The fluid is being flung out the back in one instruction , but not as tight as it was live to start with in the other direction .
At these speed , the fluid in reality attain thebacksides of the stator coil blades , causing the stator to freewheelon its one - direction clutchso it does n’t hinder the fluid motivate through it .
Benefits and Weak Points of Torque Converters
In summation to the very important job of allowing your car to come to a complete stop without procrastinate the locomotive , the torsion converter actually gift your car more torsion when you accelerate out of a stop . Modern torsion converters can multiply the torque of the locomotive by two to three times . This burden only occur when the locomotive is turn over much quicker than the transmission .
In some performance applications , car will have install what ’s called ahigh - cubicle torsion converter . Compared to a normal street converter , this constituent will place world power to the wheels at a much eminent RPM ( revolutions per second ) . This means that the torque multiplicative essence of the converter happen when the engine is making stuffy to its peak power , allowing it to accelerate heavily off the line . However , this effect is not worthy in day - to - Clarence Shepard Day Jr. traffic .
At high speeds , the transmission spins at about 90 per centum of the engine speed . Ideally , though , the transmittal would move atexactlythe same speed as the engine , because this difference in speedwastes powerand causes the assembly to shed heat . This is part of the reason why cars with automatic transmissions sometimes get bad gas mileage than cars with manual transmission .
To counter this effect , some machine have a torque converter with alockup clutch . When the two halves of the torque converter get up to speed , this clutch bag locks them together , ascertain that the locomotive and gearbox twirl at the same speed and minimizing business leader departure . Manymodern automaticshave also sum up to 10 advancing gears in order of magnitude to optimize power delivery and match the efficiency of older manual design .
