DE102015122784B3 - Method for determining the time of emission of exhaust packets from an engine and determination device for determining the time of exit of exhaust packets from a motor - Google Patents

Abstract

The invention relates to a method for determining the time of emission of exhaust packets (70-73) from an engine (10), in particular from an engine (10) of a vehicle, into an exhaust pipe (20), comprising the steps of: subdividing the undiluted exhaust gas at a first location in the exhaust conduit (20) corresponding to a predetermined frequency into logical exhaust packets (70-73), determining the volume of the respective exhaust packet, assigning a timestamp to each exhaust packet, determining the transit time for each exhaust packet for the route from the engine ( 10) to the first location by means of the determined volumes, and calculating the time of exit of the respective exhaust packet from the engine (10) into the exhaust conduit (20) by means of the timestamp of the exhaust packet and by means of the determined transit time.

Description

The invention relates to a method for determining the time of emission of exhaust packets from an engine according to claim 1, a determination device for determining the time of emission of exhaust packets from an engine according to claim 6 and a vehicle having such a determination device according to claim 9.

Monitoring and measuring engine exhaust emissions is becoming increasingly important nowadays. A variety of methods for monitoring exhaust emissions of an engine are exemplified in the references DE 10 2004 049 737 A1 . DE 10 2010 031 654 A1 . DE 10 2011 013 481 A1 or Vogt M .: "Charging systems for gasoline engines in comparison", Logos Verlag Berlin, known in 2010. The exhaust gas is usually not analyzed directly at the output of the engine or collected for analysis, but is located at a distance from the output of the engine A problem with previously known methods is that a constant transit time from the engine or the output of the engine to the location of the analysis or the location of the collection point / removal of the exhaust gas was assumed for the assignment of the respective detected or measured exhaust gas values to the engine state. However, this means that the exhaust gas values are assigned to the wrong engine states, ie that, for example, high CO ₂ values are assigned to engine states with low engine speeds and vice versa.

The object of the invention is to provide a method with which it is possible to assign the detected exhaust gas values to the engine conditions that have actually exhausted the respective exhaust gas values, i. the correct engine conditions.

This object is achieved by a method for determining the time of emission of exhaust packets from an engine according to claim 1.

In particular, the object is achieved by a method for determining the time of emission of exhaust packets from an engine, in particular from an engine of a vehicle, into an exhaust pipe, comprising the steps of: subdividing the undiluted exhaust gas at a first location in the exhaust pipe according to a predetermined one Frequency in logical exhaust packets, determining the volume of the respective exhaust packet, assigning a time stamp to each exhaust packet, determining the transit time for each exhaust packet for the route from the engine to the first location by means of the determined volumes, and calculating the time of exit of the respective exhaust packet from the engine into the exhaust pipe by means of the timestamp of the exhaust gas package and by means of the specific running time. In order to determine the transit time of each exhaust gas package, the volume in the exhaust gas line filled in front of the respective exhaust gas package by measured exhaust gas packets before a measuring point is calculated step by step, by means of the determined volumes. The frequency steps and the respectively occupied volume are added up until the volume occupied by the previously measured exhaust gas packets in the exhaust gas line is greater than the volume between the engine and the measuring point.

An advantage of this is that the detected exhaust values can be assigned to the correct engine conditions, i. The detected exhaust gas values may be assigned to the engine conditions that generated the respective exhaust gases or exhaust gas values. The date of generation of the exhaust gases is thus correctly or correctly assigned to the respective detected or measured exhaust gas values. As a result, studies on emissions and emission reductions can be improved.

The volume of the respective exhaust gas package can be determined by measuring the mass flow. This increases the accuracy of the assignment of the time stamp to the exhaust gas packets.

The volume of the respective exhaust gas packet can be determined by measuring the mass flow of ambient air diluted exhaust gas at a measuring point. An advantage of this is that the method can be used in the so-called constant-volume sampling method.

In a further embodiment, the volume of the respective exhaust gas package is determined by measuring the mass flow of undiluted exhaust gas at a measuring point in the exhaust pipe, in particular at the end of the part of the exhaust pipe in which the exhaust gas flows undiluted in the exhaust pipe. An advantage of this is that the method can be used in the so-called on-board emission measurement method. In particular, the method can be used in the evaluation methods EMROAD and CLEAR.

The calculation direction of the transit time of a gas packet is reversed to the flow direction of the gas. This means that a measured emission package is introduced from the metering point into the tunnel. In the next calculation step, the emission packet measured one time step before is filled into the tunnel and thus pushes the considered emission package from the measuring point in the direction of the engine. In order to determine the transit time of each exhaust gas packet, the emission packets measured directly in time before the emission package under consideration are pushed into the volume between the engine and the measuring point until the considered cumulative volume of the previously measured emission packets is greater than the volume of the exhaust pipe between the engine and the measuring point. Thus, the considered emission package has left the volume between engine and measuring point and has been pushed further to the engine. Through this (logical) "shifting back" of the exhaust gas packets from the measuring point to the output of the engine or up to the engine, the transit time for each exhaust gas packet can be determined particularly accurately and consequently each exhaust gas packet can be assigned as accurately as possible or exactly one time stamp.

In order to determine the transit time of each exhaust gas package, the volume in the exhaust gas line filled in front of the measuring point, frequency-by-frequency, by means of the determined volumes, is calculated directly in front of the respective exhaust gas package by measured exhaust gas packets. The frequency steps and the respectively occupied volume are added up until the volume occupied by the previously measured exhaust gas packets in the exhaust gas line is greater than the volume between the engine and the measuring point. As a result, the run time for each exhaust gas packet is determined very accurately.

In another embodiment, the instantaneous state of the engine, including e.g. Speed, fuel consumption and aspirated air volume, detected at the predetermined frequency and associated with each detected state of a timestamp. As a result, the detected exhaust gas values can be stored with the respectively associated states of the engine. An advantage of this is that the exhaust emissions can be particularly easily assigned to the engine conditions.

The object is also achieved by a determination device for determining the point in time of the emission of exhaust gas packets from an engine, in particular an engine of a vehicle, into an exhaust gas line, according to claim 6.

In particular, the object is achieved by a determination device for determining the time of emission of exhaust packets from an engine, in particular an engine of a vehicle, in an exhaust pipe, comprising a partitioning device for dividing the undiluted exhaust gas at the first position in the exhaust pipe according to a predetermined frequency logical exhaust packets, and a timestamping device for assigning a timestamp to each exhaust packet, and wherein the determination device is configured such that the transit time for each volume exhaust packet from the engine to the measurement point is determined by the determined volume of each exhaust packet, and the time the leakage of the respective exhaust gas package from the engine is calculated in the gas line by means of the time stamp of the exhaust gas packet and by means of the specific transit time. In order to determine the transit time of each exhaust gas package, the volume in the exhaust gas line filled in front of the measuring point, frequency-by-frequency, by means of the determined volumes, is calculated directly in front of the respective exhaust gas package by measured exhaust gas packets. The frequency steps and the respectively occupied volume are added up until the volume occupied by the previously measured exhaust gas packets in the exhaust gas line is greater than the volume between the engine and the measuring point.

An advantage of this is that the detected exhaust values can be assigned to the correct engine conditions, i. The detected exhaust gas values may be assigned to the engine conditions that generated the respective exhaust gases or exhaust gas values. The date of formation of the exhaust gases is thus correctly or correctly assigned to the respective exhaust gases or emission values. Consequently, studies on emissions and emission reductions can be improved

The determining device may further comprise a mass flow meter for determining the volume of each exhaust gas packet. This increases the accuracy of the assignment of the time stamp to the exhaust gas packets.

In one embodiment, the determining device further comprises an engine state detecting device, wherein the engine state detecting device is configured such that the current state of the engine including e.g. Speed, fuel consumption and inducted air volume, is detected at the predetermined frequency and the respective detected state is assigned a time stamp. As a result, the detected exhaust gas values can be stored with the respectively associated states of the engine. An advantage of this is that the exhaust emissions can be particularly easily assigned to the engine conditions.

Also, the object is achieved by a vehicle having such a determination device.

Preferred embodiments will be apparent from the dependent claims. The invention will be explained in more detail with reference to drawings of exemplary embodiments. Show here

1 a schematic view of a first embodiment of the determining device according to the invention;

2 a schematic view of the calculation steps for the assignment of the time stamp to the exhaust gas packets; and

3 a schematic view of a second embodiment of the determining device according to the invention.

In the following description, the same reference numerals are used for the same and the same parts acting.

1 shows a schematic view of a first embodiment of the determining device according to the invention 5 , The determination device 5 serves to determine the timing of the exit of exhaust gas packets 70 - 73 from an engine 10 , The motor 10 especially the engine 10 a (power) vehicle, such as a car or a truck or a ship. However, it is also conceivable that the engine 10 is the engine of a stationary machine.

The determination device 5 divides the exhaust flow of the engine 10 in logical exhaust packages 70 - 73 , This means that the exhaust gas flow of the engine 10 is not physically divided (eg by flaps or similar devices), but the exhaust gas flow from the determining device 5 in (discrete) exhaust gas packages 70 - 73 is divided mathematically or logically. Between the exhaust packages 70 - 73 There is no fixed or physical limit, but this is determined more or less arbitrarily.

The exhaust gas is in the engine 10 produced. It passes from the engine outlet E or engine outlet (undiluted) through the exhaust pipe 20 of the motor 10 , At the end D of the exhaust pipe 20 of the motor 10 the exhaust gas enters the undiluted sample line 25 , At the end of the sample line 25 the exhaust gas enters the Constant Volume Sampling Tunnel (CVS tunnel) at point C (dilution point) 30 , Here is the exhaust with dilution air 40 (eg ambient air) diluted. At the exit of the CVS tunnel 30 (Point B) the diluted exhaust gas enters the diluted sample line 50 , Finally, the (diluted) exhaust gas reaches the analyzer 60 (Point a).

The determination device 5 includes a mass flow meter 80 , With the mass flow meter 80 is at a fixed frequency (eg 1 Hz), the mass of the respective exhaust gas package 70 - 73 certainly. The specified frequency thus also determines the exhaust gas package size (volume of the respective exhaust gas package). By means of the ideal gas equation, by measuring the pressure p (in the undiluted exhaust gas line 20 ) and the temperature using the gas constant of air (R) determines the exhaust gas volumetric flow V: V _i = (m _i * R * T _i ) / p

For every exhaust package 70 - 73 Thus, the volume flowed through per unit time can be calculated. The location of the measurement in the undiluted part of the exhaust pipe does not influence the result, since a change in the volume flow propagates at the speed of sound and thus the same volume flow is present in the entire undiluted part of the exhaust pipe / sample line at a respective point in time.

This will be the volume of each exhaust packet 70 - 73 certainly. The volume can be different in size because of the engine 10 Depending on the condition, more or less exhaust gas is produced. As a result, the exhaust gases move at different speeds through the exhaust pipe and arrive at different speeds, ie at different times, to the analyzer 60 ,

t_i

Zeitverschiebung [s]

V_j

Volumenpaket

∆t

Berechnungsschritt [s]

V_Abgasleitung

Volumen der Abgasleitung zwischen Messstelle und Motorauslass

The variable transport time t _i for a volume packet in a calculation step (the calculation step is eg 1 s at a frequency of 1 Hz and 0.5 s at a frequency of 2 Hz, for example) is determined from the sum of the volume packets, one after the other larger than the volume the exhaust pipe between measuring point and engine outlet are:

t _i

Time difference [s]

V _j

volume package

.delta.t

Calculation step [s]

V _{exhaust pipe}

Volume of the exhaust pipe between measuring point and engine outlet

In the thinned part of the exhaust pipe move the exhaust gas packets 70 - 73 with the same speed. In the undiluted part of the exhaust pipe 20 the exhaust packages move 70 - 73 but with different speeds.

Each detected exhaust volume packet becomes frequency step by frequency step (ie at a frequency of 1 Hz, with steps of 1 s, at a frequency of 2 Hz with steps of 0.5 s) in the direction of the motor 10 or engine output shifted, ie it is the volume integrated, which occupy the previously measured exhaust gas packets. The frequency steps are also added or integrated. This happens until the integrated volume of the exhaust gas packets 70 - 73 greater than the entire volume of the undiluted portion of the exhaust system 20 . 25 is. After that, the exhaust package 70 - 73 the corresponding, ie the (using the sum of the frequency steps) back calculated, timestamp assigned. Allocation is made on a straight-line basis according to the proportion to which the shifted exhaust package 70 - 73 lies in the individual volumes of the engine output.

In the runtime calculation, the volume of the previously measured exhaust gas package is pushed into the tunnel in each time step, and thus the considered exhaust gas package is pushed further. If the volume of all inserted exhaust gas packages is greater than the volume between engine and measuring point, then the considered exhaust gas package has reached the engine. The calculation direction is opposite to the flow direction of the gas. Therefore, the previously measured exhaust gas packets are filled into the tunnel and push the considered exhaust gas package on. 2 shows a schematic view of the calculation steps for the assignment of the time stamp to the exhaust gas packets 70 - 73 ,

First, from the time of measurement of the first exhaust gas packet 70 (The same applies to the 2nd, 3rd, 4th, etc. exhaust gas package) at the measuring point the time (back) is calculated, at which the first exhaust gas package 70 was at the point C was. It is assumed that the speed of the or each exhaust gas package 70 - 73 in the dilute part of the exhaust pipe is always constant or equal.

Subsequently, the exhaust gas packets 71 - 73 , which were measured in time before the first exhaust gas package, in the tunnel or the undiluted exhaust pipe frequency step for frequency step "pushed". Through the volumes of the exhaust gas packages 71 - 73 in front of the considered exhaust package 70 becomes the considered exhaust package 70 pushed through the tunnel. This happens as long as the considered exhaust gas package 70 the tunnel or the undiluted part of the exhaust pipe 20 left and (again) in the engine 10 located.

The first exhaust package 70 gets in the present example that in 2 is shown, the time stamp 10, since the first exhaust gas package 70 according to the in 2 shown calculation in the frequency step 10 completely in the engine 10 was.

At time 13 is the first exhaust gas package 70 at the point of the mixture, ie at point C. The point in time of the calculation is point in time 12, since the exhaust gas packet at this time is completely in the undiluted sample line 25 located. At time 11, the first exhaust gas package 70 in the exhaust pipe of the engine, since the exhaust gas package by the previously measured exhaust gas package 71 further into the tunnel is purely displaced.

Accordingly, for every single exhaust package 70 - 73 the variable transit time in the undiluted part of the exhaust pipe 20 calculated (modal measurement). Increasing the frequency increases the accuracy of the assignment of the time stamp, since the exhaust gas packets 70 - 73 get smaller. The second exhaust package 71 gets the timestamp accordingly 8th (not shown), since at this time, the second exhaust gas package 71 completely inside the engine 10 was.

However, the exhaust gas packages often overlap at the points A and C, respectively, and thus the beginning and end of an exhaust gas package leave the exhaust gas line / undiluted sample line in different time steps. In this case, the exhaust gas packets are logically split and assigned to the respective time steps depending on the overlapping volume. Since the real emissions in a measured time step but i.A. are not constant, arises in this division an unavoidable inaccuracy, which decreases with higher measurement frequency of the mass flow.

In the 3 The embodiment shown differs from that in FIG 1 shown embodiment only in that the mass flow meter 80 in the undiluted part of the exhaust pipe 20 located.

The mass flow meter 80 can determine the mass flow eg by means of ultrasound.

In the analyzer 60 is the composition of the exhaust gas or the exhaust gas packets 70 - 73 analyzed. This can be done, for example, by chemical and / or physical analysis. In this case, for example, the CO ₂ content and / or NO _x content or mass of the exhaust gas for each exhaust gas package 70 - 73 certainly.

In addition, the condition of the engine 10 detected by a motor state detecting device (not shown) and provided with a time stamp. The condition of the engine 10 includes, for example, speed, torque and / or sucked or injected fuel. This is combined with the analyzed values of the associated exhaust gas package 70 - 73 ie the exhaust gas package 70 - 73 that has the same timestamp saved.

It will be the exhaust masses of each at any one time an exhaust gas measurement from the engine 10 leaked exhaust packages 70 - 73 summed to determine the engine raw emissions time-resolved.

LIST OF REFERENCE NUMBERS

5

determiner

10

engine

20

Exhaust pipe of the engine

25

undiluted sample line

30

CVS-Tunnel

40

dilution air

50

diluted sample line

60

analyzer

70-73

exhaust gas packets

80

Mass flow meter

Claims (9)

Method for determining the time of exit of exhaust gas packets ( 70 - 73 ) from a motor ( 10 ), in particular from an engine ( 10 ) of a vehicle, into an exhaust pipe ( 20 ), comprising the steps of: dividing the undiluted exhaust gas at a first location in the exhaust line ( 20 ) according to a predetermined frequency into logical exhaust gas packets ( 70 - 73 ), Determining the volume of the respective exhaust packet, assigning a time stamp to each exhaust packet, determining the transit time for each exhaust packet for the distance from the engine ( 10 ) to the first location by means of the determined volumes, and calculating the time of exit of the respective exhaust packet from the engine ( 10 ) in the exhaust pipe ( 20 ) by means of the timestamp of the exhaust gas packet and by means of the determined transit time, wherein for determining the transit time of each exhaust gas packet ( 70 - 73 ), directly in front of the respective exhaust package ( 70 - 73 ), filled by measured exhaust gas packets volume in the exhaust pipe ( 20 ) before a measuring point frequency step for frequency step, by means of the specific volumes, is calculated, and the frequency steps and the respectively occupied volume are added up until by the previously measured exhaust gas packets ( 70 - 73 ) occupied volume in the exhaust pipe ( 20 ) is greater than the volume between the engine ( 10 ) and the measuring point. Method according to claim 1, wherein the volume of the respective exhaust gas packet ( 70 - 73 ) is determined by measuring the mass flow. Method according to claim 2, wherein the volume of the respective exhaust gas packet ( 70 - 73 ) is determined by measuring the mass flow of exhaust gas diluted with ambient air at a measuring point. Method according to claim 2, wherein the volume of the respective exhaust gas packet ( 70 - 73 ) by measuring the mass flow of undiluted exhaust gas at a measuring point in the exhaust pipe, in particular at the end (C) of the part of the exhaust pipe ( 20 ), in which the exhaust gas undiluted in the exhaust pipe ( 20 ), is determined. Method according to one of the preceding claims, wherein the instantaneous state of the engine ( 10 ), comprising, for example, speed, fuel consumption and intake air volume, is detected at the predetermined frequency and the respective detected state is assigned a time stamp. Determination device ( 5 ) for determining the time of the exit of exhaust gas packets ( 70 - 73 ) from a motor ( 10 ), in particular an engine of a vehicle, in an exhaust pipe ( 20 ), comprising a partitioning device for dividing the undiluted exhaust gas at the first position in the exhaust pipe ( 20 ) according to a predetermined frequency into logical exhaust gas packets ( 70 - 73 ), and a timestamp device for assigning a timestamp to each exhaust packet ( 70 - 73 ), and wherein the determining device ( 5 ) is designed such that the transit time for each exhaust gas packet ( 70 - 73 ) for the volume of the engine ( 10 ) up to the measuring point by means of the determined volume of each exhaust gas packet ( 70 - 73 ) is determined, and the time of the exit of the respective exhaust gas packet ( 70 - 73 ) from the engine ( 10 ) in the gas line by means of the timestamp of the exhaust gas packet ( 70 - 73 ) and is calculated by means of the determined transit time, whereby in order to determine the transit time of each exhaust gas packet ( 70 - 73 ), directly in front of the respective exhaust package ( 70 - 73 ), filled by measured exhaust gas packets volume in the exhaust pipe ( 20 ) before a measuring point frequency step for frequency step, by means of the specific volumes, is calculated, and the frequency steps and the respectively occupied volume are added up until by the previously measured exhaust gas packets ( 70 - 73 ) occupied volume in the exhaust pipe ( 20 ) is greater than the volume between the engine ( 10 ) and the measuring point. Determination device ( 5 ) according to claim 6, further comprising a mass flow meter ( 80 ) for determining the volume of each exhaust gas packet ( 70 - 73 ). Determination device ( 5 ) according to claim 6 or 7, further comprising an engine state detecting device, wherein the engine state detecting device is configured such that the current state of the engine ( 10 ), comprising, for example, speed, fuel consumption and intake air volume, is detected at the predetermined frequency and the respective detected state is assigned a time stamp. Vehicle with a determination device ( 5 ) according to any one of claims 6-8.

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