![]() ![]() EMI has two main classes-conducted and radiated-that can lead to longer design time to market and added cost. To reduce EMI in a design, engineers first must understand how EMI propagates into a design. The limits and methods of measurements are intended to protect onboard receivers from disturbances produced by components, such as a switching regulator in a power-supply design.ĭesigners need to fully understand CISPR and other emission standards before they begin their power designs (see References 2 and 3). CISPR 25 is one of the most stringent international emission standards for vehicles and devices targeting radio disturbance characteristics. The efforts required to achieve compliance affect both product development costs and time to market. ![]() For example, two requirements are to ensure that electronic systems don’t emit excessive EMI or noise, and be immune to the noise emitted by other systems. Regulatory compliance to EMC standards, CISPR 25 for automotive applications, is critical in a product design. The automotive industry and individual automobile manufacturers must meet a variety of electromagnetic-compatibility (EMC) requirements. These should help designers pass EMI standards testing in their respective regions. This is similar to what happens in the turbine: The fluid is being flung out the back in one direction, but not as fast as it was going to start with in the other direction.Īt these speeds, the fluid actually strikes the back sides of the stator blades, causing the stator to freewheel on its one-way clutch so it doesn't hinder the fluid moving through it.Covered here will be EMI filtering and other system techniques that can be integrated into the system architecture to minimize RF EMI interference, both conducted and radiated. If you were standing in the back of a pickup moving at 60 mph, and you threw a ball out the back of that pickup at 40 mph, the ball would still be going forward at 20 mph. At this point, the fluid returns from the turbine, entering the pump already moving in the same direction as the pump, so the stator is not needed.Įven though the turbine changes the direction of the fluid and flings it out the back, the fluid still ends up moving in the direction that the turbine is spinning because the turbine is spinning faster in one direction than the fluid is being pumped in the other direction. There is a point, around 40 mph (64 kph), at which both the pump and the turbine are spinning at almost the same speed (the pump always spins slightly faster). Something a little bit tricky happens when the car gets moving. We'll take a closer look at the stator in the next section. This is why a torque converter has a stator. If the fluid were allowed to hit the pump, it would slow the engine down, wasting power. If you look at the arrows in the figure above, you can see that the fluid exits the turbine moving opposite the direction that the pump (and engine) are turning. The fluid exits the turbine at the center, moving in a different direction than when it entered. So as the turbine causes the fluid to change direction, the fluid causes the turbine to spin. And whatever applies the force that causes the object to turn must also feel that force, but in the opposite direction. ![]() In order to change the direction of a moving object, you must apply a force to that object - it doesn't matter if the object is a car or a drop of fluid. This is where it connects to the transmission. The torque converter turbine: Note the spline in the middle. It is this directional change that causes the turbine to spin. This means that the fluid, which enters the turbine from the outside, has to change direction before it exits the center of the turbine. You can see in the graphic below that the blades of the turbine are curved. The turbine causes the transmission to spin, which basically moves your car. The fluid then enters the blades of the turbine, which is connected to the transmission. The pump section of the torque converter is attached to the housing. As fluid is flung to the outside, a vacuum is created that draws more fluid in at the center. As it spins, fluid is flung to the outside, much as the spin cycle of a washing machine flings water and clothes to the outside of the wash tub. The pump inside a torque converter is a type of centrifugal pump. How the parts of the torque converter connect to the transmission and engine ![]()
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