Due to its inherent design, an automobile engine is subject to rotating fluctuations. Such fluctuations are caused by explosive combustion of the fuel and by imbalances in the crankshaft and other inertial components. Variation in engine revolution is one of the leading causes of noise and vibration problems in the drivetrain.
While driving, except for the drive gear, the other gears are freely spinning on the shaft and when rotating, the meshing of the gears generates a rattling noise that can be heard within the cabin. This rattling noise is not only heard directly by the driver, it is also transmitted through the shift lever and other elements of the clutch environment.
To prevent such noise, the NVH is absorbed by a clutch damper function which suppresses the movement of the free, spinning gears and attenuates the vibration transmitted to the transmission. The clutch damper function is provided by a series of springs located between the flywheel and the transmission. If the spring used for the clutch is not appropriate at certain engine speeds, the vibration in the transmission and the differential gear will be amplified. This will aggravate the noise of gear rattling and transmit more vibration to the vehicle body. By using a spring with the appropriate rigidity, the engine vibration is prevented from being transmitted to the transmission.
From a vehicle manufacturer's perspective, the cabin noise in the vehicle must be as quiet as possible. Here's where dampening comes into play; a damper system improves the driving comfort and delivers a reduction in NVH (noise, vibration and harshness). EXEDY employs the latest noise and vibration analysis technology to develop clutch dampers that ensure quiet and comfortable driving. What's more, our damper systems also limit the possibility of mechanical damage by reducing shock loading through the driveline.
The first type of clutch disc is a conventional sprung disc, with a low angular displacement. A typical kind of disc found in a petrol clutch kit for petrol applications made up of a single splined hub with typically four or six torsion springs. It's a relatively simple design, and it's quite suitable for gasoline or petrol type engines.
By far, this is the most common form of dampening within passenger and commercial vehicles until recent years. Springs included within the clutch driven disc hub allow dampening of torsional shock loadings when the clutch is engaged.
Conventional Clutch Disc Characteristics:
When it comes to diesel vehicles or more modern engines with higher NVH, we need to look at something a little bit more sophisticated than a conventional sprung disc. The next level of damper that EXEDY manufactures delivers a more complex construction of the disc required by more modern gasoline applications. The silent type disc or multistage disc, as opposed to the conventional style, is built with a two-piece spline hub, which delivers two stages of noise and vibration absorption. Within this type of damper, we have what we term an idle spring and as the name suggests, the idle spring absorbs noise and vibration at idle, providing dampening at the first stage. Once the vehicle is underway, the torsion springs start absorbing NVH operating between 7 degrees to 18 degrees of movement.
Silent Type Clutch Disc Characteristics:
Primarily for diesel applications, EXEDY has manufactured a silent type disc called the Wide-Angle Damper, also known as N.V.R. type disc in the Aisin range. This type of disc offers the most sophisticated design to absorb noise and vibration, and similarly to the silent type disc, it delivers superior multistage dampening.
Within the clutch, you will find the friction washer, a two-piece spline hub, the idle springs and the torsion springs. A WAD type disc has a vast angular displacement and softer springs, with a slightly different construction that allows the damper to rotate 30 to 40 degrees in angular rotation. The difference between the wide-angle damper and the silent type disc, as the name suggests, is the length and angular movement of the springs, which enables much superior dampening than the other styles of dampers.
A WAD type disc delivers three stages within the damper mechanism; the first stage at idle, the second stage up to about 26 degrees of angular movement and the final stage out to 28 degrees of movement. This design enables increased torsional angular displacement and longer reduced spring rate (softer) springs within the clutch driven disc hub, allowing more refined dampening. This type of clutch disc is commonly used within late passenger and light - heavy commercial vehicles.
WAD Type Clutch Disc Characteristics:
EXEDY is dedicated to the development of the best drivetrain dampers in the world by emphasizing quietness and comfort, fuel economy and other environmental concerns based on a thorough understanding of customer needs.
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