Page 58 - Automotive Engineering Powertrain Chassis System and Vehicle Body

Emissions control CHAPTER 3.1

Fig. 3.1-2 Top, in 1992, a hot transient mode, (b) was added to the earlier EEC test cycle, (a). Sampling begins after 40 s. The lower
limit, (d ) is for vehicles incapable of attaining the higher maximum speed. Mid-left, the Japanese 10 mode cycle, which has to be run
through 6 times. Mid-right, the Japanese 11 mode cycle to be run through 4 times. Below, Japanese hot transient test introduced in the
early 1990s, comprising 24 s idle, the first three modes of its predecessor and a 15 mode high speed, or hot, test. Bottom, US Federal
Test Program (FTP).

termed the hot transient stage of a journey started with while NO x emissions are of little significance except
a hot engine. under hot running conditions.
By applying weighting factors to alter the relative Conditions that encourage the generation of NO x in
effects of the three bag analyses on the totals, the results the combustion chamber are principally temperatures

of the test are easily adjusted to represent different above about 1350 C in the gas at high pressures and
characteristic types of operation. Obviously HC emis- the length of dwell at those temperatures. Exhaust
sions are high for the period following starting from cold, gas recirculation (EGR) was introduced to lower the

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