Advanced Automotive Fault Diagnosis
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LÔØI NOÙI ÑAÀU, ledklok
- Điều hướng trang này:
- 2.4.3 Noise conditions
| 2.4.2 Noise, vibration and
harshness Noise, vibration and harshness (NVH) concerns have become more important as drivers have become more sensitive to these issues. Drivers have higher expectations of comfort levels. Noise, vibration and harshness issues are more noticeable due to reduced engine noise and better insulation in general. The main areas of the vehicle that pro- duce NVH are: ● tyres; ● engine accessories; ● suspension; ● driveline. It is necessary to isolate the NVH into its specific area(s) to allow more detailed diagnosis. A road test as outlined later is often the best method. The five most common sources of non-axle noise are exhaust, tyres, roof racks, trim and mouldings, and transmission. Ensure that none of the following conditions is the cause of the noise before proceeding with a driveline strip down and diagnosis. 1. In certain conditions, the pitch of the exhaust may sound like gear noise or under other con- ditions like a wheel bearing rumble. 2. Tyres can produce a high pitched tread whine or roar, similar to gear noise. This is particu- larly the case for non-standard tyres. 3. Trim and mouldings can cause whistling or whining noises. 4. Clunk may occur when the throttle is applied or released due to backlash somewhere in the driveline. 5. Bearing rumble sounds like marbles being tumbled. 2.4.3 Noise conditions Noise is very difficult to describe. However, the following are useful terms and are accompanied by suggestions as to when they are most likely to occur. ● Gear noise is typically a howling or whining due to gear damage or incorrect bearing pre- load. It can occur at various speeds and driv- ing conditions, or it can be continuous. ● ‘Chuckle’ is a rattling noise that sounds like a stick held against the spokes of a spinning bicy- cle wheel. It usually occurs while decelerating. ● Knock is very similar to chuckle though it may be louder and occurs on acceleration or deceleration. Check and rule out tyres, exhaust and trim items before any disassembly to diagnose and correct gear noise. tải về 7.07 Mb. Chia sẻ với bạn bè của bạn:
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