Page 729 - Automotive Engineering Powertrain Chassis System and Vehicle Body

CHAP TER 2 2. 1 Exterior noise: Assessment and control

3. Product Conformity Assessment (assessing the is placed on the manufacturer to ensure that the product
ability to produce series products in conformity with complies with the appropriate requirements.
the specification, performance and labelling/marking The original technical Directive relating to type ap-
requirements of the type approval). proval and noise was 70/157/EEC. This defined limiting
noise levels outside the vehicle during a particular form
In the United Kingdom, the Vehicle Certification of acceleration test (the test being improved since then
Agency (VCA – an executive agency of the Department and now detailed in ISO 362:1998). An acceleration test
of the Environment, Transport and the Regions – was chosen to provide a vehicle operating condition with
DETR) is the only Competent Authority (as defined in worst-case noise emissions. The original test was as
70/156/EEC) for the type approval of vehicles under follows:
EC Directives. The VCA is therefore the only body
in the UK to issue EC type approval certificates. The test site, a section of level road (more than 3 m
However, an EC type approval certificate issued by wide) in an open area of minimum radius 50 m, is
a Competent Authority in another Member State is constructed in accordance with ISO 10844. ISO
equally valid in all Member States including the UK. 10844 defines the texture and porosity and hence
The VCA is also the only test authority in the UK for the acoustic effect of the road surface. The road
EC type approval. In other Member States, such as widens at one point to make a 20 m by 20 m test
Germany, there are several test authorities but only one area of special road surface as shown in Fig.
Government Authority may issue type approval 22.1-1.
certificates. A line is drawn down the centre line of the road. The
EC Component Type Approval may be obtained for driver follows that line throughout the test.
generic components (to be fitted to any vehicle) after One microphone position is marked on each side
evaluation against particular technical EC Directives. EC of the road, 7.5 m from the centre point of the
Separate Technical Unit Type Approval may be obtained test area and at a height of 1.2 m. A type 1 sound
for components to be fitted to only one type of vehicle level meter is placed at one of the microphone
after evaluation against particular technical EC positions.
Directives. The test vehicle approaches the test area at a fixed
EC approval of most new mass-produced road vehi- speed and in a predetermined gear. For common
cles is based on whole vehicle approval. In such cases, EC passenger cars of category M1 with 5-speed
a representative example of the production intent vehicle manually operated transmissions the approach speed
is tested/evaluated by the Competent Authority (they is 50 km hr 1 and the test is performed in both
must at least attend all tests if they do not actually second and third gears.
conduct them). The items tested include: When the front of the vehicle enters the 20-m long
seat belts test area, the driver depresses the throttle briskly
lights and fully and holds it in that position until the rear of
the vehicle leaves the test area.
tyres
brakes The maximum, fast-weighted, A-weighted, noise
emissions (including noise) level recorded whilst the vehicle is within the test
seats and head restraints area is noted. The results are considered valid when
four consecutive results are within 2 dB from each
reward visibility other.
vehicle impact test.
At least four valid levels are recorded on both sides of
Compliance with around 45 technical standards is the vehicle.
checked. VCA practises worst case selection in order to
reduce the amount of testing needed across a range of
product types. (Source: www.vca.gov.uk.)
10 m
7.5
22.1.1.2 EC noise homologation
7.5
Current EC automotive Directives are what are known as 10 m
old approach whereby a third party tests for compliance
with the requirements of particular technical Directives.
10 m 10 m
In new approach Directives (that Member States have so
far rejected for automotive applications) more obligation Fig. 22.1-1 The test area defined in ISO 362:1998.

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