AT525576A4 - Device and method for exhaust gas measurement on a test object - Google Patents

Abstract

The invention relates to a device (1) for measuring exhaust gas on a test object (2) to which intake air (AL) can be supplied via an intake line (7) and can be drawn off from the exhaust gas (AG) via an exhaust line (11), the intake line (7 ) upstream of the test specimen (2) is and/or can be connected to a supply line (5) for intake air (AL), and an exhaust gas measuring unit (3) is provided which is connected to the exhaust gas line (11) of the test specimen (2) and via a The diluting line (8) is and/or can be connected to the supply line (5) upstream of the test specimen (2), an outlet line (9) for discharging a measurement gas (MG) from the exhaust gas measurement unit (3) being provided, which is connected to the exhaust gas measurement unit ( 3) and is connected to a suction device (4). According to the invention, a bypass line (6) is provided which branches off from the feed (5), intake (7) or diluter line (8) upstream of the test object (2) and opens into the outlet line (9) downstream of the exhaust gas measuring unit (3), and in the delivery pipe (5) upstream of a connection of the intake air pipe (7) to the delivery pipe (5) and/or upstream of a connection of the diluting pipe (8) to the delivery pipe and/or upstream of the branch of the bypass pipe (6) from the delivery pipe ( 5) or the suction line (7) or the dilution line (8) a gas supply unit (10) is arranged.

Description

15

20

25

30

35

AV-4288 AT

Device and method for exhaust gas measurement on a test object

The present invention describes a device and a method for measuring exhaust gas on a test specimen, to which intake air can be supplied via an intake line when the device and the test specimen are used as intended and can be derived from the exhaust gas via an exhaust gas line, with the intake line upstream of the test specimen having a feed line for intake air is connected and/or connectable, and an exhaust gas measuring unit is provided, which is and/or can be connected to the exhaust gas line of the test specimen and is and/or can be connected to the supply line via a diluting line upstream of the test specimen, with an outlet line for discharging a measurement gas is provided from the exhaust gas measurement unit, which is connected to the exhaust gas measurement unit

and is connected to a suction device.

On the basis of regulatory framework conditions, exhaust gas measurements of vehicles are often carried out as real driving emissions (RDE) during a real test drive of a vehicle on a test site or on the public road network. However, such RDE journeys are complex, the results depend on the current environmental conditions and the traffic situation, and specially equipped test vehicles are required for this. As an alternative to this, whole vehicles are tested separately on a roller test stand or parts of vehicles on a test stand.

For example, a combustion engine can be tested on an engine test bench.

Due to the increasingly strict legal framework, representative measurements of exhaust gases from an internal combustion engine are becoming increasingly important, since there are often also normative or norm-like regulations for maximum emissions, for example from

vehicles.

In addition to the classic combustion products such as carbon dioxide, carbon monoxide, nitrogen oxides, methane and polycyclic aromatic hydrocarbons and the like, fine dust particles such as soot particles and the number of soot particles are also of interest in the exhaust gas measurement. A Constant Volume Sampling (CVS) system is used in the operation of a test bench to determine the mass of these exhaust gas components. All of the exhaust gas is fed into the CVS system and diluted with filtered air in such a way that a constant volume flow is always achieved. The total flow rate is measured and a proportionate sample of the total flow rate is continuously collected in bags. After the test, the samples from the bags are analyzed as quickly as possible, but usually after 20 minutes at the latest. An optimized measuring range can be set for each exhaust gas analyzer by means of adjustable throughput levels

to be set.

2118

15

20

25

30

35

AV-4288 AT

As described above, test benches are able to realistically specify the various loads on a test object, such as a vehicle or an internal combustion engine, i.e. to simulate uphill and downhill gradients, for example. However, different ambient pressures (at a certain altitude, i.e. the height above sea level) affect the operation of a combustion engine and thus also the composition of the exhaust gas. Due to the different total pressure, the partial pressures of the combustion educts and products in the exhaust gas also change accordingly and can therefore influence the concentration of the exhaust gas analytes in the exhaust gas via the chemical equilibrium. Condensation reactions of exhaust gas analytes are also possible as a result of pressure changes and can also have effects on the concentrations of the exhaust gas analytes. It is also possible that condensation reactions affect particle sizes in the exhaust gas. For example, the pressure at 2000 meters above sea level is only 77% compared to 0 meters above sea level. Thus, a climb of a test car on a

Test stand with regard to the exhaust gas measurement can only be mapped insufficiently.

To regulate the pressure, the entire test bench can be placed in a height chamber. However, this leads to high design and equipment costs, since the entire

test stand must be covered.

In the prior art, as described for example in US Pat. No. 7,818,379 B2, DE 10 2017 205 995 A1 and EP 2 295 950 B1, a test object, for example an engine or a test vehicle, is supplied with intake air at a specific pressure. A specific ambient pressure can thus be simulated on the intake side. However, the pressures on the exhaust gas side are different and there can therefore be changes in the exhaust gas composition on the way to the exhaust gas measurement unit. Thus, no representative measurement of the

exhaust gas are ensured.

WO 2008/036993 A1 discloses an engine test bench on which a test specimen and an exhaust gas measuring unit are arranged and a blower generates a reduced pressure after the exhaust gas measuring unit in order to set the required volume flow through a CVS. However, with this setup there is a pressure gradient along the measurement setup, so that the pressure for the air supply to the test object and for the measurement of the exhaust gas is not the same, which again results in the same problems with the exhaust gas measurement

result.

The object of the present invention is therefore an improved measurement of

To enable exhaust gas analysis from a test object on the test bench.

The object is achieved by a device according to the invention in that a bypass line is provided which is upstream of the test specimen from the

Feed line or suction line or diluter line branches and downstream

3118”

15

20

25

30

35

AV-4288 AT

of the exhaust gas measurement unit opens into the exhaust line, and that in the feed line upstream of a connection of the intake air line with the feed line and/or upstream of a connection of the diluter line with the feed line and/or upstream of the branching of the bypass line from the feed line or the

Intake line or the diluter line, a gas supply unit is arranged.

This is advantageous because a certain suction pressure can be set by the flow control unit and the suction device. The bypass line then makes it possible for a uniform pressure level to prevail in the entire test bench, ie upstream and downstream of the test object and in particular also in the exhaust gas measuring unit and downstream of the exhaust gas measuring unit. This means that there is no negative influence on the exhaust gas measurement on the test bench and different ambient pressures can be reliably simulated on the test bench. It can thus be a representative measurement of the

Exhaust gas done at a set pressure.

In an advantageous embodiment, the gas supply unit is designed to provide a volume flow of intake air in the supply line. This allows the precise gas flow to be set in the device and thus can also be used in conjunction with

the suction device, a precise pressure can be set in the device.

In a further advantageous embodiment, at least one branch is arranged in the feed line downstream of the gas feed unit in order to branch off the bypass line, the intake line and the diluter line. A gas flow in the device can thus be controlled in a targeted manner. Advantageously, valves can be used in the branches, which a precise distribution of the gas flows, such as the

Intake air allow.

In a further advantageous embodiment, a first control flap is arranged in the supply line downstream of the gas supply unit and upstream of the bypass line, the suction line and the diluting line, in order to adjust a supply volume flow in the supply line. A volume flow can thus only be set roughly via the gas supply unit and the fine control is carried out via the first control flap. With it

an even more precise pressure regulation can take place in the device.

In a further advantageous embodiment, a second control valve is arranged downstream of where the bypass line joins the outlet line and upstream of the suction device in the outlet line, in order to set a discharge volume flow in the outlet line. With the second control flap, precise regulation is possible

of the suction device and thus enable very precise pressure control.

In a further advantageous embodiment, the gas supply unit is designed

to condition provided intake air. This can be based on given conditions, such as

4118”

15

20

25

30

35

AV-4288 AT

Weather conditions, are optimally received, and thus a very precise test run of the

test object can be realized.

In a further advantageous embodiment, the relative humidity, the temperature and/or a pre-pressure of the intake air is to be set. All parameters of the intake air for the test run can thus advantageously be specified. Adjusting the relative humidity can suffice to represent various geographically different climatic conditions. A form can, for example, be adapted to high or low pressure weather conditions. The temperature can also represent different climatic conditions. This allows a test run to be very accurate

seasonal and geographic conditions.

In a further advantageous embodiment, a control unit is provided, which controls the gas supply unit and/or the first control flap for setting the supply volume flow and/or the suction device and/or the second control flap for setting

of the discharge volume flow controls.

In a further advantageous embodiment, a pressure measuring device is provided in the supply line or the bypass line or the intake line or the diluter line or the outlet line in order to measure the pressure and the control unit, depending on the measured pressure, the gas supply unit and/or the first control valve for adjusting the supply volume flow activates and/or activates the suction device and/or the second control flap for adjusting the discharge volume flow. This allows the pressure measurement to be controlled by using the pressure measurement device to obtain an actual

value of the pressure is transmitted to the control unit.

An exhaust gas measurement is advantageously carried out on a test specimen, with the test specimen being connected to the intake line in order to supply intake air to the test specimen and being connected to the exhaust gas line in order to discharge exhaust gas from the test specimen, with a pressure in the test specimen being used to simulate an altitude of the test specimen Intake line and the outlet line is adjusted by controlling at least one of the gas supply unit, the first control flap of the suction device and the second control flap. In this way, for example, different weather conditions with different air pressure and/or mountain trips can be set by the control unit. These pressure specifications can be provided by a simulation unit

and are transmitted to the control unit.

The subject invention is explained in more detail below with reference to FIGS. 1 to 2, which are advantageous by way of example, diagrammatically and not by way of limitation

Show configurations of the invention. show it

51187

15

20

25

30

35

AV-4288 AT

1 shows a device according to the invention for measuring the exhaust gas of a test object

Pressure control, and Figure 2 an advantageous embodiment of the device for measuring exhaust gas.

Fig. 1 shows the device according to the invention for measuring exhaust gas on a test specimen 2. A test specimen 2 can be, for example, an entire vehicle on a roller test bench, or part of a vehicle, such as an internal combustion engine on an engine test bench or a drive train with an internal combustion engine on a drive train test bench. A test specimen 2 preferably has an internal combustion engine, but a test specimen 2 based on another system, such as a fuel cell, can also be measured as the energy source. In principle, any type of test object 2 is conceivable in which the aim is to analyze the composition and components of an exhaust gas AG. At a

Fuel cell exhaust gas can be the discharged anode or cathode gas.

The device 1 is therefore preferably a test bench set up accordingly for carrying out the exhaust gas measurement. Such test benches are sufficiently well known for various test specimens, which is why we only go into them here to the extent that it is necessary for understanding the invention. Other devices that are usually present and known on a test bench, such as a loading machine for the test object, a test bench control unit, other measuring devices, etc., are described in

Figures not shown because they are irrelevant to the invention.

In order to operate the test object 2 in the device 1 , intake air AL is supplied to it via an intake line 7 . The intake air AL is used to carry out a redox process in test object 2, e.g. combustion, in addition to the fuel, such as diesel, petrol or hydrogen. In the simple case of an Otto engine or diesel engine, ambient air can be supplied, with the fuel being converted in the internal combustion engine and combustion products being generated in the process, which are discharged with the exhaust gas AG. In a fuel cell, ambient air can also be supplied, usually at the cathode. However, it is also possible to supply gases other than ambient air, for example pure oxygen, nitrogen and others. The combustion products can be, for example, carbon dioxide (CO), carbon monoxide (CO), polyaromatic hydrocarbons (PAH), methane (CHa), nitrogen oxides (NOx), particles or soot particles, etc. In the case of a fuel cell, a reaction product can only be water vapor (H2O). Each combustion product can thus be an exhaust gas component in the exhaust gas AG, which can be measured and/or analyzed in the course of an exhaust gas measurement. The products of combustion are discharged as exhaust gas AG to an exhaust pipe 11 connected to the specimen 2. The exhaust pipe 11 can

to an exhaust pipe in the case of a whole vehicle or to an exhaust manifold

6118”

15

20

25

30

35

AV-4288 AT

be tightly connected to an internal combustion engine. In the case of a fuel cell, the exhaust line 11 can be connected to the cathode or anode exhaust line. The

Exhaust gas AG is discharged from test object 2 via exhaust pipe 11 .

The exhaust gas AG of the test specimen 2 is fed to an exhaust gas measuring unit 3 via the exhaust line 11 . For this purpose, the exhaust gas measuring unit 3 is connected to the exhaust gas line 11 downstream of the test object 2 . The exhaust gas measuring unit 3 is also supplied with intake air AL via a thinner line 8 . The intake air AL can be used to dilute the exhaust gas and/or to operate the exhaust gas measuring unit 3 . The exhaust gas AG is advantageously routed via a Constant Volume Sampling (CVS) unit as an exhaust gas measuring unit 3, which intake air AL is used for suitable dilution of the exhaust gas AG. In the CVS unit, the exhaust gas AG is collected in bags and either analyzed online, i.e. immediately during the exhaust gas measurement by a measuring unit,

or analyzed offline after the test run on the test bench in an external measuring unit.

In an advantageous embodiment, the exhaust gas measuring unit 3 consists of a dilution unit in which the exhaust gas AG of the test object 2 is diluted with intake air AL in a predetermined ratio and a measuring unit in which the diluted exhaust gas

or at least one exhaust gas component in the exhaust gas is measured and/or analyzed.

The measurement unit of the exhaust gas measurement unit 3 can be designed to analyze at least one exhaust gas component. For this purpose, for example, a flame ionization detector (FID), chemiluminescence (CLD), an infrared measurement (IR)), an ultraviolet/visible measurement (UV/VIS) or a mass spectrometric measurement can be provided. The intake air AL can be used as a dilution gas so that the concentrations of the exhaust gas components to be measured are in a range to be analyzed. In some methods, it is also possible that the exhaust gas measurement unit 3 can measure a plurality of exhaust gas components, such as Faourier Transform Infrared Spectroscopy (FTIR). The measurement method can also depend on the exhaust gas component to be analyzed. For example, particles as an exhaust gas component in the exhaust gas AG require different measurement methods than gaseous ones

exhaust components.

The intake air AL is supplied via a supply line 5 which is located upstream of the dilution line 8 and the intake line 7 . The intake air AL supplied via the feed line 5 is divided in a predetermined ratio upstream of the test piece 2 into the intake line 7, the thinner line 8 and a bypass line 6, which is explained in greater detail below. For this purpose, a branch 12 can be provided in the supply line 5, with which the intake line 7, the dilution line 8 and the bypass line

6 are connected. The branch 12 can, for example, a cross piece or a

7118

15

20

25

30

35

AV-4288AT

be a combination of tees. However, it is also possible for the branch 12 to contain a valve or a flow control. In this way, the distribution of the intake air AL between the thinner line 8, the intake line 7 and the bypass line 6 can be controlled. However, it is also conceivable for the intake air to be divided over a number of branches 12, 12', with the intake line 7 branching off from the supply line 5 at a first branch 12 and, downstream of this, the bypass line 6 at a second branch 12' from the Diluter line 8 (as shown in Fig.2). However, the arrangement of the branches 12, 12' can also be reversed,

so that the bypass line 5 branches off upstream of the intake line 7 .

The intake air AL is provided by a gas supply unit 10 to which the supply line 5 is connected. The gas supply unit 10 is connected to a gas source 17 of the device 1

connected.

In the simplest embodiment, a gas supply unit 10 can be a mass flow or volume flow control unit which is connected to a compressed air supply as the gas source 17 of the device 1 . It is also possible to supply the gas supply unit 10 with synthetic air or a certain gas from a gas bottle as the gas source 17 or another suitable container. Other gases can also be fed accordingly. This can be beneficial, as compressed air often contains contaminants, such as oil residue from a compressor, and these can then be avoided. Such impurities, such as oil residues, can have a direct influence on a measurement result

Have exhaust gas measuring unit 3.

The gas supply unit 10 can contain a volume flow control and specifies a predefined supply volume flow V/m1 of intake air AL. However, the supply volume flow Vm1 can also be adjusted in a separate unit upstream or downstream of the gas supply unit 10, for example with a control valve 13 downstream of the gas supply unit 10, as in FIG. The supply volume flow Vm1 corresponds at least to the volume flow of intake air AL required by the test specimen 2 and the exhaust gas measurement unit 3 . Any excess intake air AL can be diverted via the bypass line 6 . The gas supply unit 10 can also be connected to a control unit 15

and be controlled by it.

The gas supply unit 10 is advantageously designed as a gas conditioning unit. The gas conditioning unit can be used to specify a preset temperature T, an air humidity rH, a supply volume flow \\m1 and/or a form p1 for the intake air AL. A form p1 of the intake air AL may be necessary in order to achieve a defined

To generate supply volume flow Vm1. Such gas conditioning units are dem

15

20

25

30

35

AV-4288AT

Those skilled in the art are well known and can be used in test benches of all kinds

become.

The exhaust gas measurement unit 3 supplies a measurement gas to an outlet line 9 connected to it

MG off. The measuring gas MG is usually a mixture of exhaust gas AG and intake air AL.

According to the invention, a bypass line 6 is provided in the device 1 . The bypass line 6 branches off from the feed line 5 (as in FIG. 1) or the intake line 7 or the diluting line 8 (as in FIG. 2) upstream of the test object 2 . For this can

Branches 12, 12' can be arranged in the corresponding lines.

For example, the bypass line 6, the intake line 7 and the thinner line 8 branch off from a branch 12, which is designed, for example, as a cross piece, in the supply line 5 (as in FIG. 1). However, the bypass line 6 can also branch off at a further branch 12' in the thinner line 8 (as in FIG. 2) or in the intake line 7, which is then designed as a T-piece. Likewise, in the supply line 5 (such as

in Fig.1) a branch 12 may be provided at which the intake line 7 branches off.

The bypass line 6 opens into the outlet line 9 downstream of the exhaust gas measuring unit 3. This allows pressure equalization in the device 1 between the supply line 5 and the outlet line 9 to be achieved, so that the pressure on the intake side and the pressure on the exhaust gas side on the test object 2 are the same. Pressure losses through pipes or any installations in the pipes can also be taken into account here. Then the bypass line 6

be dimensioned in such a way that the resulting pressure loss is minimized.

A suction device 4 is arranged on the outlet line 9 downstream of the exhaust gas measuring unit 3 . The suction device 4 is designed to suck in the measurement gas MG with a discharge volume flow Vm2. The pressure p2 in the lines of the device 1 can thus be set with the suction device 4 and the set discharge volume flow Vm2. The suction device 4 can also be connected to the control unit 15

be connected (as in Figure 2) to allow regulation of the pressure p2.

The suction device 9 can have gas treatment so that pollutants in the measurement gas MG are not released into the environment. For this purpose, for example, filter systems, such as electrostatic precipitators or carbon filters, and condensation units can be provided.

CO2 scrubbers or CO2 (carbon) capture units are also conceivable.

2 shows an advantageous embodiment of the device according to the invention. In this embodiment, a first control flap 13 is arranged in the supply line 5 upstream of the distribution of the intake air AL to the intake line 7 , the dilution line 8 and the bypass line 6 . The first control flap 13 is designed to have a supply volume flow \Vm1 in the

To control supply line 5, and thus also the amount of supplied intake air AL

9/18”

15

20

25

30

35

AV-4288AT

set. In this embodiment, the gas supply unit 10 provides a gas as intake air AL, preferably a conditioned gas, and the first control valve 13 sets the supply volume flow \V\m1. In such an embodiment, volume flow control in the gas supply unit 10 is not absolutely necessary. For this purpose, the first control flap 13 can be connected to the control unit 15, which controls the first control flap 13 in order to set the desired or required supply volume flow Vm1. The use of the first control flap 13 for controlling the supply volume flow Vm1 also enables a faster change in the supply volume flow Vm1 and thus a more dynamic one

Regulation of the supply volume flow Vm1.

The pressure p2 (indicated in FIG. 1) in the outlet line 9 and the intake line 7, the

Diluter line 8 and the bypass line 6 set.

Advantageously, a second control valve 14 is arranged downstream of where the bypass line 5 joins the outlet line 9 . The second control valve 14 can also be connected to a control unit 15 and controlled by it. The second control flap 14 then adjusts the discharge volume flow Vm2. In this case, the suction device 4 does not have to adjust the discharge volume flow /m2 and can then be operated, for example, at an advantageous constant operating point. The use of the second control flap 14 for controlling the discharge volume flow \\m2 also enables a faster change in the discharge volume flow \\m2 and thus a more dynamic regulation of the discharge volume flow Vm2. Thus, one is very accurate

Pressure control of the pressure p2 in the device 1 possible.

A control valve 13, 14 can, for example, as a ring throttle valve, flanged throttle valve

or butterfly valve.

A first external pressure p1 can thus be present upstream of the first control flap 13 and a second external pressure p3 can be present downstream of the second control flap 14 . The first external pressure p1 and the second external pressure p3 can also be the same and, for example, correspond to the current air pressure at the installation site of the device 1 . A form pv of a gas supply unit 10 as a gas conditioning unit can also correspond to a first external pressure p1

are equivalent to.

Due to the interaction of the set supply volume flow Vm1 and the discharge volume flow Vm2, which are set, for example, via the first control flap 13 and the second control flap 14, in the lines of device 1 (intake line 7, diluter line 8, bypass line 6, outlet line 9) compared to a prevailing Ambient pressure, a negative pressure or positive pressure can be generated. This

Negative pressure or positive pressure is the same upstream and downstream of test specimen 2,

"-9

15

20

25

30

AV-4288AT

which improves the performance of the exhaust gas measurement. The same pressure p2 can thus be specified both for the test specimen 2 during operation and for the exhaust gas measuring unit 3 for the measurement

become.

The bypass line 6 allows the pressure p2 in the lines of the device 1 to be constant and no pressure gradients to form. Such a pressure gradient can be caused, for example, via the exhaust gas measurement unit 3 . On a CVS unit, it can

a pressure drop over the filling of the bags can be caused.

In an advantageous embodiment, the gas supply unit 10 generates a predetermined volume flow of intake air AL. The first control flap 13 adjusts this volumetric flow to a predetermined supply volumetric flow Vm1 of the intake air AL. The first control flap 13 is controlled by the control unit 15 for this purpose. The second control valve 14 before

Suction device 4 sets the discharge volume flow Vm2.

To simulate pressure conditions at altitudes with a pressure below 1 bar, the discharge volume flow \/m2 is greater than the supply volume flow Vm1. However, it is also conceivable to specify overpressures, ie a pressure greater than 1 bar. Then the discharge volume flow \V/m2 can be smaller than the supply volume flow Vm1. Due to the fact that the pressure is directly proportional to the amount of gas, the regulation of the pressure p2 in the lines of the device 1 is dependent on the amount of substance of the gas in the lines. That can

approximately by the ideal gas equation PV=nRT—>p-n

be described, where at constant volume V, and constant temperature T of

Pressure p is directly proportional to the amount of substance n of the gas in the device 1.

To adjust the pressure p2 in the lines of the device 1, a pressure measuring unit 18 can also be provided in one of the lines (intake line 7, dilution line 8, bypass line 6, outlet line 9) of the device 1, which measures the current pressure in the lines. The measured pressure can then be supplied to the control unit 15, which then adjusts the pressure to a predetermined target pressure via the first control flap 13 (and/or via the gas supply unit 10) and/or the second control flap 14 (and/or

via the suction device 4).

The control unit 15 is advantageously connected both to the gas supply unit 10, the suction device 4, to the first control flap 13 and the second control flap 14 and

controls them accordingly.

A user interface can be present on the control unit 15, on which, for example

a pressure p2 to be set can be entered by an operator.

15

AV-4288AT

It is also possible for the control unit 15 to be coupled to a system control unit 16, as in FIG. The system control unit 16 can thus specify a test run, during which execution different altitudes can also be simulated, for example in the form of a test specimen 2 driving uphill. Changing weather conditions with changes in the air pressure can thus also be mapped. The control unit 15 then sets the

Pressure defaults of the plant control unit 16 in the device 1 to.

The control unit 15 or the system control unit 16 can also be provided to the test specimen 2, and possibly also other devices of the device 1, such as a connected to the test specimen 2 loading machine, according to

To control specifications of the test run to be carried out.

The control unit 15 and/or the system control unit 16 can be microprocessor-based hardware (e.g. a computer), an integrated circuit such as a Field Programmable Gate Array (FPGA) or an application-specific integrated circuit (ASIC), also with a microprocessor, or an analog one circuit or

to be an analog computer. Mixed forms are also conceivable.

-11

Claims (18)

15 20 25 30 35 AV-4288 AT patent claims 1. Device (1) for measuring exhaust gas on a test specimen (2), which, when the device (1) and the test specimen (2) are used as intended, can be supplied with intake air (AL) via an intake line (7) and from the exhaust gas (AG) via a The exhaust gas line (11) can be derived, the intake line (7) being and/or being connectable to a supply line (5) for intake air (AL) upstream of the test specimen (2), and an exhaust gas measuring unit (3) being provided which is connected to the is and/or can be connected to the exhaust gas line (11) of the test specimen (2) and is and/or can be connected to the supply line (5) via a thinner line (8) upstream of the test specimen (2), with an outlet line (9) for discharging a measurement gas (MG) from the exhaust gas measurement unit (3), which is connected to the exhaust gas measurement unit (3) and to a suction device (4), characterized in that a bypass line (6) is provided, which is upstream of the test object (2) from the feed line (5) or the intake line (7) or the diluter line (8) and opens into the outlet line (9) downstream of the exhaust gas measurement unit (3), and that in the feed line (5) upstream of a connection of the intake air line (7) with the feed line (5) and/or upstream of a junction of the diluting line (8) with the feed line and/or upstream of the branching of the bypass line (6) from the feed line (5) or the intake line (7) or a gas supply unit (10) is arranged on the thinner line (8). 2. Device (1) according to claim 1, characterized in that the gas supply unit (10) is formed in the supply line (5) has a volume flow of intake air to provide. 3. Device (1) according to Claim 1 or 2, characterized in that downstream of the gas supply unit (10) in the supply line (5) at least one branch (12, 12°) is arranged in order to connect the bypass line (6) to the intake line (7 ) and the thinner line (8) to branch off 4. Device (1) according to one of claims 1 to 3, characterized in that downstream of the gas supply unit (10) and upstream of the bypass line (6), the suction line (7) and the diluting line (8) in the supply line (5) a first control valve (13) is arranged in the supply line (5) a supply volume flow (Vm1) to set. 5. Device (1) according to any one of claims 1 to 4, characterized in that downstream of the confluence of the bypass line (6) in the outlet line (9) and upstream of the suction device (4) in the outlet line (9) a second control flap 13 / 18 degrees 15 20 25 30 35 AV-4288AT (14) is arranged to in the outlet line (9) a discharge volume flow (Vm2) set. 6. Device (1) according to any one of claims 1 to 5, characterized in that the Gas supply unit (10) is designed to condition the provided intake air (AL). 7. Device (1) according to claim 6, characterized in that the gas supply unit (10) the relative humidity (rH), the temperature and / or a form (pv) of intake air adjusts. 8. Device (1) according to one of Claims 1 to 7, characterized in that a control unit (15) is provided which controls the gas supply unit (10) and/or the first control flap (13) for setting the supply volume flow (Vm1) and / or the suction device (4) and / or the second control flap (14) for adjusting the discharge volume flow (Vm2) controls. 9. Device (1) according to claim 8, characterized in that a pressure measuring device (18) is provided in the supply line (5) or the bypass line (6) or the intake line (7) or the diluting line (8) or the outlet line (9). in order to measure the pressure (p2) and the control unit (15), depending on the measured pressure (p2), controls the gas supply unit (10) and/or the first control flap (13) to adjust the supply volume flow (Vm1) and/or the Suction device (4) and / or controls the second control valve (14) to set the discharge volume flow (Vm2). 10. A method for measuring exhaust gas on a test object (2), with a supply line (5) providing intake air (AL), the test object (2) being connected and/or connectable via an intake line (7) connected to the supply line (5). first part of the intake air (AL) provided is supplied and when the test object (2) is in operation, an exhaust gas (AG) is discharged from the test object (2) to an exhaust pipe (11), with an exhaust gas measuring unit (3) receiving the exhaust gas (AG) via the exhaust line (11) and a second portion of the intake air (AL) provided is supplied via a dilution line (8) connected and/or connectable to the supply line (5) and the exhaust gas (AG) with the second portion of the intake air (AL) to one Measuring gas (MG) is diluted, and the exhaust gas measuring unit (3) is connected to an intake device (4) via an outlet line (9), characterized in that upstream of the test specimen (2) the feed line (5) and/or the intake air line ( 7) and/or the diluting line (8) and downstream of the exhaust gas measurement unit (3) the outlet line (9) is/are connected by means of a bypass line (6), and that via a gas supply unit (10) in the supply line (5) upstream of a connection the intake air duct (7) with the supply duct (5) and/or upstream of a connection of the diluter duct (8) with the supply duct and/or upstream of the branch of the Bypass line (6) from the supply line (5) or the suction line (7) or the 14/18” 15 20 25 30 35 AV-4288AT Thinner line (8) and/or via the intake device (4) a pressure (p2) in the intake air line (7), thinner line (8), bypass line (6) and the outlet line (9) is set. 11. The method according to claim 10, characterized in that a volume flow Intake air is provided by the gas supply unit (10) in the supply line (5). 12. The method according to claim 10 or 11, characterized in that by a first control valve (13) which is located downstream of the gas supply unit (10) and upstream of the bypass line (6), the intake line (7) and the diluting line (8) in the supply line (5) is arranged, in the supply line (5) a supply volume flow (Vm1) is set. 13. The method according to any one of claims 10 to 12, characterized in that by a second control valve, which downstream of the junction of the bypass line (6) in the outlet line (9) and upstream of the suction device (4) in the outlet line (9) (14) is arranged, in the outlet line (9) a discharge volume flow (Vm2) is adjusted. 14. The method according to any one of claims 10 to 13, characterized in that the provided intake air (AL) is conditioned by the gas supply unit (10). 15. The method according to claim 14, characterized in that on the gas supply unit (10) the relative humidity (rH), the temperature and / or a form (pv) of intake air is adjusted. 16. The method according to any one of claims 10 to 15, characterized in that a control unit (15) which controls the gas supply unit (10) and/or the first control flap (13) for setting the supply volume flow (Vm1) and/or the suction device (4) and/or the second control valve (14) for adjusting the discharge volume flow (Vm2) is controlled. 17. The method according to claim 16, characterized in that the pressure ( p2) is measured and the gas supply unit (10) and/or the first control flap (13) for adjusting the supply volume flow (Vm1) is controlled by the control unit (15) depending on the measured pressure (p2) and/or the suction device (4) and/or the second control valve (14) is actuated to set the discharge volume flow (/m2). becomes. 18. Use of the device (1) according to one of Claims 1 to 9 for carrying out an exhaust gas measurement on a test object (2), the test object (2) being connected to the intake line (7) in order to supply the test object (2) with intake air (AL ) and with the exhaust pipe (11) is connected in order to discharge exhaust gas (AG) from the test object (2), thereby 15/18 degrees characterized in that to simulate an altitude of the test object (2), a pressure (p2) in the intake line (7) and the outlet line (9) by controlling at least one of the gas supply unit (10), the first control flap (13) of the suction device (4) and the second control valve (14) is set. 16/18”