**3. Exhaust emissions legislation for light-duty vehicles**

**Figure 2.** Equipment: (a) AVL MSS analyzers for the measurement of PM [13] and (b) TSI 3090 EEPS™ equipment for PM

**Figure 1.** SEMTECH DS analyzer used for the measurement of exhaust gaseous components under actual conditions of

size distribution under actual conditions of operation [14].

operation [12].

102 Improvement Trends for Internal Combustion Engines

From the analysis of global exhaust emission standards for passenger cars (PC) and lightduty vehicles (LDV), we know that within the present decade, these standards will undergo modifications in all regions of the world (**Figure 4**). Due to the global reach of production and sales of motor vehicles by a variety of carmakers, a trend of unification of the test procedures is conspicuous. The exhaust emission limits are to remain varied and the introduction by a given legislator of additional tests will be allowed.

Currently homologation according to the ECE R83/06 directive describing the requirements for the obtainment of the Euro 5 and 6 standards. The details of the homologation legislation have been included in the EU (WE) 692/2008 regulation that is the amendment of regulation (WE) 715/2007. Item 1 article 3 of the (WE) 692/2008 regulation stipulates that in order to obtain a WE homologation in terms of exhaust emissions and the information related to vehicle repair and maintenance, the manufacturer confirms that the vehicles conform to the testing methods described in III–VIII, X–XII, XIV, and XVI of the said regulation. Aside from the said tests, the manufacturers are obliged to perform a procedure for conformity in operation, to check the operation of the on-board diagnostic system (OBD) and perform a measurement of the emission of CO2 and fuel consumption. The regulation also includes the limits of individual exhaust components. For spark ignition engines of the Euro 6 standard, a limit of

**2.** changing the mass of CO2

**3.** introducing a limit of NO2

low temperatures; and

equivalent;

lates and the procedures of their measurement.

**1.** Class 1—low power output vehicles, PWr ≤ 22;

**2.** Class 2—vehicles in the range 22 < PWr ≤ 34; and **3.** Class 3—high power output vehicles, PWr ≥ 34.

construed as CO2

in the CoC mass of greenhouse gases as an equivalent of CO2

limit. The maxi-

, under

105

and NO2

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and increasing or canceling the limit of the sum of hydrocarbons. Methane would then be

mum value of the emission must be determined based on the assessment of consequences;

**5.** authorizing the European Commission to update the limits of mass and number of particu-

The most important amendment of the homologation procedures of PC and LDV vehicles is the replacement of the New European Driving Cycle (NEDC) with worldwide harmonized light vehicles test procedures (WLTP). They assume a global harmonization of driving cycles used for the testing of motor vehicles performed on chassis dynamometers. In ECE/TRANS/WP.29/2014/27 [20], a proposal has been presented for new test cycles that will be implemented in 2017. Three types of test cycles have been determined in this document, classified according to unit index of

power (the ratio of effective power to the curb weight of the vehicle—PWr coefficient):

**Figure 5.** Curves of the WLTC driving cycle for vehicles: (a) Class 1, (b) Class 2, and (c) Class 3 [21].

**4.** supplementing of the tests (Type 6) with emission measurement of NOx

emission into the supplement to the total NOx

Measurement of Exhaust Emissions under Actual Operating Conditions with the Use of PEMS...

**Figure 4.** World emission standards 2010–2020 [16].

the particulate number (PN) was introduced for vehicles fitted with direct injected engines. Such regulations were not applicable in earlier standards.

Beside the exhaust emission limits, a very important aspect is the reduction of the emission of CO2 from a fleet of vehicles. This emission is tantamount to fuel consumption. In 2007, European Commission (EC) proposed a 30% reduction of the emission of greenhouse gases in developed countries by 2020 and that the EU itself should undertake to reach at least a 20% reduction of these gases. Aside from the environmental aspects, the introduction of these regulations aims at accelerating and facilitating of the introduction of ultra low emission vehicles manufactured by the EU members. Regulation WE 443/2009 is applicable for the M1 vehicle category while WE 510/2011 is dedicated for the N1 category. Both legislations set the admissible limits of the road emission of CO2 , potential transition periods and deviations from these limits. The measurement of the CO2 emission from both groups of vehicles is performed according to the methodology set forth in WE 715/2007 [17–19].

Prior to introducing the Euro 6 standard, an amendment of a series of regulations was planned. At the end of 2014, The European Commission passed to the European Parliament a motion (COM(2014) 28 final version) to amend the WE 715/2007 and WE 595/2009 regulation related to vehicle homologation procedures. The most important changes were as follows [16]:

**1.** increasing the gross vehicle weight from regulation WE 715/2007 (Euro 5 and 6) for the M1 , M2 , N1 , and N2 vehicle categories from 2610 to 5000 kg;


The most important amendment of the homologation procedures of PC and LDV vehicles is the replacement of the New European Driving Cycle (NEDC) with worldwide harmonized light vehicles test procedures (WLTP). They assume a global harmonization of driving cycles used for the testing of motor vehicles performed on chassis dynamometers. In ECE/TRANS/WP.29/2014/27 [20], a proposal has been presented for new test cycles that will be implemented in 2017. Three types of test cycles have been determined in this document, classified according to unit index of power (the ratio of effective power to the curb weight of the vehicle—PWr coefficient):


the particulate number (PN) was introduced for vehicles fitted with direct injected engines.

Beside the exhaust emission limits, a very important aspect is the reduction of the emission

Prior to introducing the Euro 6 standard, an amendment of a series of regulations was planned. At the end of 2014, The European Commission passed to the European Parliament a motion (COM(2014) 28 final version) to amend the WE 715/2007 and WE 595/2009 regulation related to vehicle homologation procedures. The most important changes were as follows [16]:

**1.** increasing the gross vehicle weight from regulation WE 715/2007 (Euro 5 and 6) for the M1

vehicle categories from 2610 to 5000 kg;

 from a fleet of vehicles. This emission is tantamount to fuel consumption. In 2007, European Commission (EC) proposed a 30% reduction of the emission of greenhouse gases in developed countries by 2020 and that the EU itself should undertake to reach at least a 20% reduction of these gases. Aside from the environmental aspects, the introduction of these regulations aims at accelerating and facilitating of the introduction of ultra low emission vehicles manufactured by the EU members. Regulation WE 443/2009 is applicable for the M1 vehicle category while WE 510/2011 is dedicated for the N1 category. Both legislations set the

, potential transition periods and deviations from

,

emission from both groups of vehicles is performed

Such regulations were not applicable in earlier standards.

according to the methodology set forth in WE 715/2007 [17–19].

admissible limits of the road emission of CO2

these limits. The measurement of the CO2

**Figure 4.** World emission standards 2010–2020 [16].

104 Improvement Trends for Internal Combustion Engines

of CO2

M2 , N1

, and N2

**Figure 5.** Curves of the WLTC driving cycle for vehicles: (a) Class 1, (b) Class 2, and (c) Class 3 [21].

For the Class 1 vehicles, the worldwide harmonized light-duty test cycle (WLTC) test is composed of three parts representing the driving conditions with two low and medium speed (**Figure 5a**). Its maximum value is 49.1 and 64.4 km/h, respectively. The average speed in the entire cycle is 33.3 km/h (counted without vehicle stationary) or 26.8 km/h including the vehicle stops that total 21.1% of the entire test duration. The test designed for Class 2 vehicles has an additional phase representing high speeds (**Figure 5b**). Its total time amounts to 1800 s and the vehicle covers a distance of 22.649 km. The values of the maximum and average speeds are different than those of the Class 1 vehicles. The most complex is the WLTC test for Class 3 vehicles (**Figure 5c**). It is composed of four phases. In the final part of the test, the vehicle develops a speed of 131.3 km/h [22]. In relation to the NEDC test, it is a 10% increase. The total WLTC test time for this class of vehicles is 1800 s. Comparing the WLTC test with the NEDC one, we can see a fundamental difference related to the velocity curve—the NEDC test is composed of repeated segments, while the WLTC tests have different velocity profiles that are a representation of the actual driving cycle. High variability of acceleration is a characteristic of these tests compared to the NEDC test of constant accelerations (**Table 1**).

The work area of a combustion engine in the emission homologation tests is much smaller than the area occurring under actual operation (**Figure 6**). For this reason, an introduction of new methods of exhaust emissions measurements to the existing test procedures was proposed (real driving emissions). Portable emission measurement equipment will be used for this purpose (PEMS). On 10 March 2016, an EU Regulation—(UE) 2016/427 [23] was published containing a detailed description of the performance of these measurements for PC and LDV vehicles.

Measurement of Exhaust Emissions under Actual Operating Conditions with the Use of PEMS...

Two vehicles were selected for the evaluation of the start-stop system. Vehicle A was fitted

catalytic converter (**Table 2** and **Figure 7**). The engine was characterized with a volumetric

and was lower by 17% than the index of vehicle A. The engine of this vehicle was fitted with

ditions of the vehicle in traffic in the Poznań city. The vehicle route during the tests has been

The length of the route was 12.71 km. It was diversified and included a typical urban portion and an extra-urban portion where it was possible to drive at highway speeds (with a maximum speed of 120 km/h). The extra-urban portion was 5.5 km long. As shown in **Figure 8**, the length of the vehicle route during the road test was similar to that of the NEDC test [3]. The driving time in the road tests of approximately 1200 s was similar to that of the NEDC test.

. In this case, the volumetric power output index amounted to 58.7 kW/dm3

, fitted with a three-way

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107

. Vehicle B was fitted with a diesel engine of the displace-

, CO, and THC) were performed under real operating con-

**4. Tests of PC and LDV vehicles**

power output index of 70.8 kW/dm3

ment of 3.0 dm3

**4.2. Testing methods**

shown in **Figure 8**.

Exhaust emission tests (CO2

**Table 2.** Characteristics of the tested objects.

**4.1. Characteristics of the research objects and testing methods**

a diesel oxidation catalyst (DOC) and a diesel particulate filter.

, NOx

**Parameter Vehicle A Vehicle B**

Engine displacement 0.9 dm3 3.0 dm3 Cylinder number and arrangement Straight—2 V—6

Volumetric power output index 70.8 kW/dm3 58.7 kW/dm3 Injection system MPI Common rail Aspiration Turbocharger Turbocharger Aftertreatment system TWC EGR, DPF, DOC Type of transmission Automatic Automatic

Type of ignition Spark ignition Compress ignition

Maximum torque 145 N m @ 1800 rpm 550 N m @ 2000–2250 rpm

with a turbocharged gasoline engine of the displacement of 0.9 dm3


**Table 1.** Characteristics of the NEDC and WLTC emission tests [20, 21].

**Figure 6.** Engine parameters in different emission tests [22].

The work area of a combustion engine in the emission homologation tests is much smaller than the area occurring under actual operation (**Figure 6**). For this reason, an introduction of new methods of exhaust emissions measurements to the existing test procedures was proposed (real driving emissions). Portable emission measurement equipment will be used for this purpose (PEMS). On 10 March 2016, an EU Regulation—(UE) 2016/427 [23] was published containing a detailed description of the performance of these measurements for PC and LDV vehicles.
