WO2015044256A1

WO2015044256A1 - Exhaust gas removal probe

Info

Publication number: WO2015044256A1
Application number: PCT/EP2014/070467
Authority: WO
Inventors: Klaus-Christoph Harms; Alexander Bergmann
Original assignee: Avl List Gmbh
Priority date: 2013-09-25
Filing date: 2014-09-25
Publication date: 2015-04-02
Also published as: AT513007A2; AT513007B1; AT513007A3; DE112014004412A5

Abstract

The aim of the invention is to reduce pressure pulses in an exhaust gas removal probe (1) when removing exhaust gas from the exhaust pipe (2) of a vehicle or an internal combustion engine. This is achieved in that a tubular exhaust gas removal probe (1) is provided with a first axially extending exhaust gas removal probe section (11) and a second axially extending exhaust gas removal probe section (12) which adjoins the first section. The first exhaust gas removal probe section (11) is arranged at a first axial end (5) of the exhaust gas removal probe (1), and the tubular exhaust gas removal probe (1) is closed at the end face at the first axial end (5). At least one opening (10) is provided in the circumferential face (6) of the first exhaust gas removal probe section (11), wherein the opening forms a feed channel to the exhaust gas removal probe (1), said feed channel extending over the axial length (l_F) of the first exhaust gas removal probe section (11).

Description

Exhaust gas sampling probe

The subject invention relates to an exhaust gas sampling probe and the use of the exhaust gas sampling probe for the removal of exhaust gas from an exhaust of a vehicle or an internal combustion engine.

For research and development on internal combustion engines and vehicles, the measurement of the exhaust particles is of particular importance. In this case, exhaust gas sampling probes are used with which exhaust gas from the exhaust of the internal combustion engine or the vehicle is removed. The exhaust gas is then fed via an exhaust pipe to an exhaust gas measuring device, where it can be used for a variety of measured variables, such as Emissions, particle number, particle size distribution, etc., is examined.

It is known e.g. Exhaust gas sampling probes in the form of a frontally open tube, which is inserted into the exhaust. A spacer may be disposed on the tube to hold the probe spaced from the exhaust wall in the exhaust. The exhaust gas sampling probe is inserted axially, with the end open at the front end in the exhaust pipe of the vehicle and fixed, for example, with a spring clip on the tailpipe. As a result of the directed in the axial direction against the exhaust gas flow opening of the exhaust gas sampling probe but not only reach the end of the tailpipe relatively low pressure fluctuations, but also the considerable, resulting from backpressure of the pulsating flow of exhaust gas in the exhaust pressure pulsations in the Abgasaufnahmesondenrohr and the subsequent measurement system Complex measures in the meter are required to compensate for these pressure pulsations.

It is therefore an object of the subject invention to provide an exhaust gas sampling probe for the removal of exhaust gas from an exhaust, can be reduced with the pressure pulsations in the exhaust gas sampling probe.

This object is achieved in that the tubular exhaust gas sampling probe with a first, axially extending exhaust gas sampling probe section and an adjoining second axially extending exhaust gas sampling probe section is performed, wherein the first exhaust gas sampling probe portion is disposed at a first axial end of the exhaust gas sampling probe and the tubular exhaust gas sampling probe on the first axial end is closed at the end and in the peripheral surface of the first Abgasaufnahmesondenabschnitts at least one opening is provided which forms an over the axial length of the first exhaust gas sampling probe section extending inflow channel to the exhaust gas sampling probe. Due to the fact that the inflow channel extends over an axial length, a determination of the pressure pulsations in the exhaust gas emission be reached, causing pressure pulsations in the tailpipe not or only weakened in the exhaust gas sampling probe, and thus in the downstream measuring instruments propagate.

The opening can be designed as an axial slot, or a plurality of openings can be provided, which are arranged distributed axially over the first exhaust gas sampling probe section. Likewise, a plurality of openings can be arranged distributed in the circumferential direction. It is always essential here that an inflow channel extending in the axial direction through the opening (s) results for the exhaust gas sampling probe.

In order to achieve an advantageous as isokinetic exhaust gas removal, the sum of the cross-sectional areas of all openings is equal to the flow cross-section of the exhaust gas sampling probe. Isokinetic here means that the velocity of the flow into and through the exhaust gas sampling probe does not change.

It is particularly advantageous if the length of the first exhaust gas sampling probe section, on which the openings are arranged, corresponds to at least half the diameter, preferably two thirds of the diameter, of the exhaust in which the exhaust gas sampling probe is arranged according to operation. The resulting pressure pulsations in the exhaust gas sampling probe are significantly reduced when the length of the first exhaust gas sampling probe section is chosen in relation to the exhaust pipe diameter.

In order to reliably prevent ambient air from being sucked into the exhaust gas sampling probe, the length of the second exhaust gas sampling probe section preferably corresponds to at least five times the diameter of the exhaust gas in which the exhaust gas sampling probe is operatively arranged.

With a second exhaust gas sampling probe section as a double-walled pipe section, an effective temperature control of the exhaust gas line can be achieved, as a result of which it is also possible to dispense with heating elements on the exhaust gas line. In this case, the axial end of the double-walled pipe section can be closed or open on the front side, that is to say on the side directed against the exhaust gas flow when used. When the end is closed, heat insulation in the form of an insulating air cushion is formed, and with the end open, hot exhaust gas flows through the double-walled section, whereby the exhaust gas line is tempered.

However, the filling of the double-walled pipe section with exhaust gas can also advantageously take place through many small openings which are arranged in the outer circumferential surface of the double-walled pipe section, as a result of which a detail is described below size-selective particle filter results and a relatively clean, largely freed from larger particles exhaust gas passes into the double-walled pipe section.

By a spacer on the exhaust gas sampling probe is achieved that the exhaust gas sampling probe is arranged in the exhaust at a radial distance, thereby preventing any condensate collecting in the exhaust is sucked into the exhaust gas sampling probe.

Preferably, the exhaust gas sampling probe is connected via an exhaust pipe or directly to an exhaust gas conditioning device. In particular, in the direct arrangement of the exhaust gas sampling probe on an exhaust gas conditioning device, or in a very short exhaust pipe, can be dispensed with a possible required heating an interposed exhaust pipe, which significantly reduces the cost of the measuring system.

By means of a curved exhaust sampling probe in front of the exhaust conditioning means, downstream components, such as e.g. an exhaust gas conditioning, advantageously kept from the hot, chemically aggressive exhaust gas jet.

The subject invention will be explained in more detail below with reference to Figures 1 to 5, which show by way of example, schematically and not by way of limitation advantageous embodiments of the invention. It shows

1 shows an exhaust gas sampling probe according to the invention in an exhaust,

FIGS. 2 and 3 embodiments of the exhaust gas sampling probe with double-walled exhaust gas sampling probe section,

4 shows a block diagram of an exhaust gas measuring device connected to the exhaust gas sampling probe and

5 shows an embodiment of a connected to the exhaust gas sampling probe exhaust gas conditioning.

1, a tubular exhaust gas sampling probe 1 according to the invention is arranged in an exhaust tailpipe of an exhaust 2. For this purpose, the exhaust gas sampling probe 1 is axially inserted into the exhaust 2, here in the tailpipe, and fixed by means of a fixing unit 3, here for example in the form of a spring clip attached to the exhaust gas sampling probe 1 on the exhaust 2. The exhaust gas sampling probe 1 is preferably made of stainless steel in order to withstand the chemically aggressive exhaust gas constituents and to prevent excessive cooling of the exhaust gas in the exhaust gas sampling probe 1. The exhaust gas taken with the exhaust gas sampling probe 1 is fed to an exhaust gas measuring device 8 via an exhaust gas line 7 connected to the exhaust gas sampling probe 1. In or after the flue gas meter 8 is preferably a suction pump 9 (indicated in Figure 1) arranged to suck exhaust gas from the exhaust 2 through the exhaust gas sampling probe 1.

The tube cross-section of the exhaust sampling probe 1 may be circular, but may also take other forms which are not prone to particulate contamination, e.g. oval, rectangular or polygonal with no sharp corners.

Arranged on the axial end 5 of the exhaust gas sampling probe 1 facing the exhaust gas flow, a spacer 4 is provided on which the exhaust gas sampling probe 1 is kept at a distance from the pipe wall of the exhaust 2, in order to prevent any condensate collecting in the exhaust 2 enters the exhaust gas sampling probe 1. However, the spacer 4 may also be attached to another location of the exhaust sampling probe 1, e.g. shown in Fig.2.

The exhaust sampling probe 1 is preferably curved in the area located outside of the exhaust 2 during use, which facilitates attachment to the exhaust 2 and prevents equipment connected downstream of the exhaust sampling probe 1, such as e.g. an exhaust gas conditioning device 20 are exposed directly to the hot exhaust gas jet.

The exhaust gas sampling probe 1 is closed on the front side (ie, on the side of the stream directed against the exhaust gas flow during the use according to the invention) on the axial end 5 arranged in the exhaust 2. In the region of the axial end 5, at least one opening 10 is provided on the peripheral surface 6 of the exhaust gas sampling probe 1 at a first exhaust gas sampling probe section 1, through which an inflow channel is formed, through which exhaust gas from the exhaust 2 can flow into the exhaust gas sampling probe 1. The opening 10, or the forming inflow channel, extends substantially over the axial length l _{F of} the first exhaust gas sampling probe section 1 1. Preferably, exhaust gas is sucked with the suction pump 9 through the opening 10 in the exhaust gas probe 1.

The inflow channel into the exhaust gas sampling probe 1 can also be designed in the form of several distributed openings 10. As openings 10, for example, holes distributed over the circumference are provided, as shown in FIG. For example, three in each case lying in a cross-sectional plane, offset by 120 ° holes, with several such drilling arrangements are arranged axially one behind the other, here, for example, six axially successively arranged bore arrangements, each with three holes offset by 120 °. The axially consecutively arranged bore arrangements can in turn be rotated by a certain angle, in this case for example 180 °. Of course, other openings 10 and arrangements of openings 10 are conceivable, such as circumferentially distributed, axial slots (as shown in Figure 2) or distributed in the axial direction slots in the circumferential direction (as shown in Figure 3). Likewise, of course, combinations of different openings 10 are conceivable. It is essential that the inflow channel to the exhaust gas sampling probe 1 is distributed over an axial length l _F.

For this purpose, it is advantageous if the sum of the areas A _{F of} the openings 10 corresponds approximately to the flow cross-section A _{s of} the exhaust gas sampling probe 1, that is, if ZA _F = A _S , since then a possible isokinetic exhaust gas removal is achieved.

The length l _{F of} the first exhaust gas sampling probe section 1 1 at the axial end 5 of the exhaust gas sampling probe 1, on which the openings 10 are arranged, is selected such that possible pressure pulsations in the exhaust gas stream in the exhaust gas sampling probe 1 are as much as possible. For this purpose, the openings 10 are distributed to the exhaust gas sampling probe 1 over a certain length l _F , wherein the length l _{F is} greater than or equal to half, preferably two-thirds, of the exhaust pipe diameter D. Furthermore, it is desirable to provide a second exhaust gas sampling probe section 12 having a length l _s without openings 10, which is arranged during use in the exhaust 2, this length l _{s being} greater than or equal to five times the exhaust pipe diameter D is, so l _s ^ 5-D, since then it can be safely prevented that ambient air is sucked into the exhaust gas sampling probe 1 from outside the exhaust 2.

The cross section A _F , or in the case of bores of the diameter, the openings 10, can be selected so that a size-selective particle filter is formed. There is a known relationship between cross section A _F , flow velocity in the exhaust gas sampling probe 1 (or exhaust gas mass flow) and the size of the particles in the exhaust gas flow, which are sucked through the openings 10. Thus, on the basis of the openings 10 and the resulting flow velocity (depending on the negative pressure in the exhaust gas sampling probe 1 and the cross section A _{s of} the exhaust gas sampling probe 1) in the exhaust gas sampling probe 1 (for example, specified by the suction pump 9) a separation characteristic can be set in the particle certain Size in exhaust gas should not be sucked into exhaust gas sampling probe 1. This cut-off point for exhaust gas measurements is typically about 2.5 μm, which is achieved, for example, with openings 10 in the form of bores having a diameter of 1.5 mm and an exhaust gas mass flow in the exhaust gas sampling probe 1 of 5 l / min.

In a possible advantageous embodiment of the exhaust gas sampling probe 1, the second exhaust gas sampling probe section 12, which has no openings 10, and preferably also the optionally connected to the exhaust gas sampling probe 1 exhaust pipe 7, double-walled, as shown in Figure 2. The arranged in proper use in the exhaust 2 axial end of the double-walled pipe section 13 is closed at the end, so that in the double-walled pipe section 13, ie between the inside lying tube and outer pipe 14, an air cushion forms, which acts as a heat-insulating and thus a cooling the exhaust gas in the exhaust gas sampling probe 1 or in the exhaust pipe 7 is prevented or at least considerably reduced. This otherwise unnecessary heating elements for the exhaust pipe 7 are obsolete. In the double-walled pipe section 13, of course, a vacuum can be generated, which further increases the heat-insulating effect.

In an alternative to this, the double-walled pipe section 13 may be open on the front side on the axial end 5 facing the first exhaust gas sampling probe section 11 with opening (s) 10, as shown in FIG. Hot exhaust gas flows from the exhaust pipe 2 in the double-walled pipe section 13 between the inner pipe and the outer pipe 14, as a result of which the exhaust gas sampling probe 1 and a possible exhaust pipe 7 are tempered at the same time. Before the exhaust gas measuring device 8, or an exhaust gas conditioning device 20, the double-walled pipe section 13 opens to the outside, to allow a flow of exhaust gas through the double-walled pipe section 13.

The filling of the double-walled pipe section 13 with exhaust gas can, however, also take place with closed end face of the double-walled pipe section 13 exclusively or in the case of an open end face, also by many small inlet openings 15 arranged in the outer circumferential surface of the outer pipe 14 of the double-walled pipe section 13 are as indicated in Fig.2. As a result of the above-described effect of the separation of large particles at the small inflow openings 15, a relatively clean exhaust gas, which is largely freed from larger particles, will enter the double-walled pipe section 13.

The exhaust gas sampling probe 1 supplies exhaust gas for a downstream downstream exhaust gas meter 8. In front of the exhaust gas meter 8, an exhaust gas conditioning device 20 may be connected upstream. 4, an embodiment of an exhaust gas measuring device 8 is shown schematically. Here, the exhaust gas measuring device 8 is designed with two channels in that the supplied exhaust gas stream in the exhaust gas measuring device 8 is split into two parallel arranged measuring lines 28, 29 with particle measuring devices 21, 22, such as scattered light measuring devices, opacimeters, particle counters, aerosol electrometers, etc. arranged therein. Of course, however, more than two measuring channels, or even a single measuring channel, may be provided. It is likewise conceivable to arrange two particle measuring devices 21, 42 one behind the other in a measuring line 28, 29, as indicated in FIG. When using multiple particle gauges 21, 22, 42, the sensitivity of the exhaust gas measuring device 8 can be increased by using particle measuring devices 21, 22, 42 with different resolutions and / or measuring ranges.

In order to be able to easily adjust the volume flow through the individual exhaust gas measuring devices 8, a bypass line 24 arranged parallel to the measuring lines 28, 29 can be provided with a filter unit 23. In each of the lines, a critical orifice 25, 26, 27 may additionally be arranged, which also serves to control the volume flows in the individual lines 24, 28, 29. Downstream of the particle measuring devices 21, 22, 42, the individual lines 24, 28, 29 are brought together again to form an outlet line 31, in which a pulsation damper 30 can be arranged. In the outlet 31, the suction pump 9 can also be arranged. In addition, a safety valve 32 may be provided on the outlet side in order to prevent a backflow of ambient air into the measuring channels of the exhaust gas measuring device 8.

A dilution stage 56 can also be provided in the exhaust gas conditioning unit 20, in which the withdrawn exhaust gas is diluted with gas or preferably with particle-free air, as will be described in detail below with reference to FIG. To provide the pure air required for this purpose, air treatment can also be provided in the exhaust gas measuring device 8, as shown by way of example in FIG. In this case, ambient air is sucked in with a dilution air pump 33, cooled in a gas cooler 34, dried in a condensate separator 35, and filtered in filter units 36, 37. The thus treated air can then be removed and fed to an exhaust gas conditioning unit 20. In the dilution air line 38 may also be a pulsation damper 39 and a mass flow control device 40 may be arranged. Separate condensation water can be removed by means of a condensate pump 41 from the exhaust gas meter 8. In the exhaust gas conditioning unit 20, as shown in FIG. 5, a preheating section 50 is provided, for example, in which the supplied exhaust gas is preheated by means of heating element 51. In preheating 50 also volatile exhaust gas components are converted into the gas phase. Thereafter, a catalytic converter 52 connects, eg as described in AT 13 239 U1, in which volatile exhaust gas constituents are removed from the exhaust gas. The catalyst 52 comprises an oxidation catalyst 53 in which volatile organic exhaust gas constituents are burned, and a sulfur trap 54 in which volatile sulfatic particles are bound and thus removed from the exhaust gas. The catalyst 52 is preferably tempered by means of a heater 55. Connected downstream of the catalytic converter 52 is a dilution stage 56 in which the purified exhaust gas stream is diluted with pure air. Here, the dilution step 56 is carried out, for example, as a porous diluent, as described in EP 2 264 423 A2. Of course, other embodiments of the dilution stage 56 are conceivable, for example as a rotary diluent, as described in EP 2 025 979 B1, or as a well-known dilution tunnel. An embodiment of the exhaust gas conditioning device 20 without a downstream dilution stage 56 is also conceivable.

The exhaust gas conditioning device 20 may be connected via an exhaust pipe 7, or directly, to the exhaust gas sampling probe 1.

Claims

claims

1 . A tubular exhaust gas sampling probe having a first, axially extending exhaust gas sampling probe section (11) and a second, axially extending exhaust gas sampling probe section (12), the first exhaust gas sampling probe section (11) at a first axial end (5) of the exhaust gas sampling probe (1) is arranged, wherein the tubular exhaust gas sampling probe (1) at the first axial end (5) is closed at the end and in the peripheral surface (6) of the first Abgasaufnahmesondenabschnitts (1 1) at least one opening (10) is provided, the one about the axial length (l _F ) of the first exhaust gas sampling probe portion (1 1) forming inflow channel to the exhaust gas sampling probe (1) is formed.

2. Tubular exhaust gas sampling probe according to claim 1, characterized in that the opening (10) is designed as an axial slot.

3. tubular exhaust gas sampling probe according to claim 1, characterized in that a plurality of openings (10) are provided, which are distributed axially over the first exhaust gas sampling probe section (1 1).

4. tubular exhaust gas sampling probe according to claim 2 or 3, characterized in that a plurality of openings (10) are arranged distributed in the circumferential direction.

5. tubular exhaust gas sampling probe according to one of claims 1 to 4, characterized in that the cross-sectional area (A _F ) of all openings (10) is substantially equal to the flow cross-section (A _s ) of the exhaust gas sampling probe (1).

6. tubular exhaust gas sampling probe according to one of claims 1 to 5, characterized in that the length (l _F ) of the first exhaust gas sampling probe portion (1 1) at least half the diameter (D), preferably two-thirds of the diameter (D), the exhaust (2 ), in which the exhaust gas sampling probe (1) is arranged according to the operation, corresponds.

7. tubular exhaust gas sampling probe according to one of claims 1 to 6, characterized in that the length (l _s ) of the second exhaust gas sampling probe portion (12) at least five times the diameter (D) of the exhaust (2), in which the exhaust gas sampling probe (1) arranged according to operation is, corresponds.

8. tubular exhaust gas sampling probe according to claim 1, characterized in that the second exhaust gas sampling probe section (12) is designed as a double-walled pipe section (13).

9. tubular exhaust gas sampling probe according to claim 8, characterized in that the first exhaust gas sampling probe section (1 1) facing the axial end of the double-walled pipe section (13) is closed at the end.

10. Tubular exhaust gas sampling probe according to claim 8, characterized in that the first exhaust gas sampling probe section (1 1) facing the axial end of the double-walled pipe section (13) is frontally open.

1 1. Tubular exhaust gas sampling probe according to one of claims 8 to 10, characterized in that on the outer peripheral surface of the double-walled pipe section (13) a plurality of inflow openings (15) are provided.

12. Tubular exhaust gas sampling probe according to one of claims 1 to 10, characterized in that on the exhaust gas sampling probe (1), a spacer (4) is arranged.

13. tubular exhaust gas sampling probe according to one of claims 1 to 12, characterized in that the first exhaust gas sampling probe section (1 1) facing away from the end of the second exhaust gas sampling probe portion (12) is curved.

14. tubular exhaust gas sampling probe according to one of claims 1 to 13, characterized in that the exhaust gas sampling probe (1) via an exhaust pipe (7) or directly with an exhaust gas conditioning device (20) is connected.

15. The use of the tubular exhaust gas sampling probe according to one of claims 1 to 14 in an exhaust gas measuring system, wherein the exhaust gas sampling probe (1) exhaust from an exhaust (2) of a vehicle or an internal combustion engine is removed and an exhaust gas meter (8) is supplied.