Method for checking the efficacy of an exhaust gas after-treatment device

Abstract

The invention relates to a method for checking the efficacy of an exhaust gas after-treatment device (9), especially of a catalyst, for an internal combustion engine, exhaust gas generated by a donor internal combustion engine (2) flowing through the exhaust gas after-treatment device (9) to be checked. In order to allow the efficacy of an exhaust gas after-treatment device (9) to be checked with a high degree of flexibility and in a simple manner, a partial quantity is withdrawn from the exhaust gas flow of the donor internal combustion engine (2) and is fed to a defined partial inlet cross-section (22) of the exhaust gas after-treatment device (9) to be checked.

Claims

1. A method for checking the efficacy of an exhaust gas after-treatment device for an internal combustion engine, comprising the following steps: (a) generating exhaust gas in a donor internal combustion engine and discharging an exhaust gas stream, (b) separating a partial exhaust gas quantity from the exhaust gas stream, (c) adding at least one reactant to the partial exhaust gas quantity, (c1) masking at least one entry or exit cross-sectional area of the exhaust gas after-treatment device, and (d) supplying the partial exhaust gas quantity with said at least one reactant to a defined partial entry cross section of the exhaust gas after-treatment device to be tested.

2. The method according to claim 1, wherein the at least one reactant added in step (c) is selected from the group consisting of CO, NO, NO.sub.2, SO.sub.2, NH.sub.3 and hydrocarbon.

3. The method according to claim 1, comprising a step of controlling a temperature of the partial exhaust gas quantity taken from the exhaust gas stream in step (b) prior to step (d).

4. The method according to claim 3, wherein the step of controlling the temperature of the partial exhaust gas quantity comprises heating the partial exhaust gas quantity.

5. The method according to claim 1, wherein the step of controlling the temperature of the partial exhaust gas quantity comprises cooling the partial exhaust gas quantity.

6. The method according to claim 1, comprising the step of compressing the partial exhaust gas quantity prior to step (d).

7. A test stand apparatus for checking the efficacy of an exhaust gas after-treatment device for an internal combustion engine, comprising a donor internal combustion engine having an exhaust line, from which at least one secondary exhaust line branches off, wherein the secondary exhaust line is connected to a defined partial entry cross section of an exhaust gas after-treatment device to be tested, so that a partial exhaust gas quantity can be taken from the exhaust gas stream via the secondary exhaust line and can be supplied to the defined partial entry cross section of the exhaust gas after-treatment device to be tested, wherein the secondary exhaust line branches off in a region of a branching point from the exhaust line, wherein the exhaust line is continued downstream of the branching point as a main exhaust line, and wherein the test stand apparatus comprises at least one screen for closing at least one entry or exit cross-sectional area of the exhaust gas after-treatment device.

8. The test stand apparatus according to claim 7, wherein a gas metering unit for introducing gas into the exhaust gas stream is provided between the donor internal combustion engine and the exhaust gas after-treatment device, the gas metering unit discharging into the secondary exhaust line.

9. The test stand apparatus according to claim 8, wherein the gas metering unit discharges at least one reactant from the group consisting of CO, NO, NO.sub.2, SO.sub.2, NH.sub.3, and hydrocarbon.

10. The test stand apparatus according to claim 7, including at least one temperature-changing device between the donor internal combustion engine and the exhaust gas after-treatment device.

11. The test stand apparatus according to claim 10, wherein the temperature-changing device includes a cooling device or a heating device.

12. The test stand apparatus according to claim 7, including at least one gas analyzer which is connected to at least one removal point for exhaust gas test quantities on the secondary exhaust line.

13. The test stand apparatus according to claim 7, including at least one compressor or at least one flow rate setting element arranged upstream of the exhaust gas after-treatment device.

14. The test stand apparatus according to claim 11, wherein the cooling device includes at least one heat exchanger or at least one electrical cooling element.

15. The test stand apparatus according to claim 11, wherein the heating device includes at least one heat exchanger or at least one electrical heating element.

16. The test stand apparatus according to claim 7, wherein at least one compressor or at least one flow rate setting element is arranged upstream of the cooling device or the heating device or the gas metering device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in greater detail hereafter on the basis of nonrestrictive exemplary embodiments, which are illustrated in the figures. In the figures:

(2) FIG. 1 shows a first variant of the test stand arrangement according to the invention for carrying out the method according to the invention; and

(3) FIG. 2 shows a second variant.

DETAILED DESCRIPTION OF THE DEPICTED EMBODIMENTS

(4) FIG. 1 schematically shows a test stand arrangement 1 for carrying out the method according to the invention. The test stand arrangement 1 has a donor internal combustion engine 2, which generates exhaust gas for the checking, having an exhaust line 3, from which a secondary exhaust line 5 branches.

(5) FIG. 2 shows a variant in which the exhaust line 3 divides at a branching point into a main exhaust line 4 and a secondary exhaust line 5. Except for this, the variants illustrated in FIG. 1 and FIG. 2 are identical, wherein identical elements bear the same reference signs in both figures.

(6) FIG. 2 shows a variant, in which the exhaust line 3 divides at a branching point into a main exhaust line 4 and a secondary exhaust line 5. Except for this, the variants illustrated in FIG. 1 and FIG. 2 are identical, wherein identical elements bear the same reference signs in both figures.

(7) A compressor 6, at least one temperature changing devicein the illustrated exemplary embodiment a cooling device 7 and a heating device 8and the exhaust gas after-treatment device 9 (for example, a catalytic converter) to be checked are arranged in the secondary exhaust line 5. A flow rate meter 10 is provided downstream of the exhaust gas after-treatment device 9. Sampling points 11 and 12 for an exhaust gas test quantity from the secondary exhaust line 5 are provided upstream and downstream of the exhaust gas after-treatment device 9, via which a small exhaust gas test quantity is supplied to a gas analyzer 13. Fundamentally, only a single such sampling point 11, 12 can also be provided either upstream or downstream of the exhaust gas after-treatment device 9.

(8) The discharge opening 14 of a gas metering device 15 is provided upstream of the exhaust gas after-treatment device 9, via which at least one additional gaseous, liquid, or solid reactant 16, for example, a harmful material for the exhaust gas after-treatment device 9 from the group CO, NO, NO.sub.2, SO.sub.2, NH.sub.3, or hydrocarbon can be supplied to the secondary exhaust line 5. The exhaust gas flow in the main exhaust line 4 is identified with reference signs 17, and the exhaust gas flow in the secondary exhaust line 5 with reference sign 18.

(9) Reference signs p and T identify measurement points for pressure and temperature, respectively, upstream of the exhaust gas after-treatment device 9, in the exhaust gas after-treatment device 9, and downstream of the exhaust gas after-treatment device 9.

(10) Via the secondary exhaust line 5, an exhaust gas partial quantity is taken from the exhaust gas of the internal combustion engine 2 and supplied to the exhaust gas after-treatment device 9 to be testedhowever, only to a partial entry cross section 22 of the exhaust gas after-treatment device 9. Therefore, exhaust gas actually only flows through a small volume portion 19 of the exhaust gas after-treatment device 9. To achieve this, the exhaust gas after-treatment device 9 is masked on the entry and exit sides by screens 20, 21, which screens 20, 21 dose the entry cross-sectional area 9a and exit cross-sectional area 9b of the exhaust gas after-treatment device 9 except for the partial entry cross section 22 or partial exit cross section 23 through which the partial exhaust gas quantity flows.

(11) Before the partial exhaust gas quantity reaches the exhaust gas after-treatment device 9 via the secondary exhaust line 5, the exhaust gas is thermally conditioned in the cooling device 7 and/or the heating device 8, i.e., brought to a desired target temperature. The cooling device 7 or heating device 8 can have a heat exchanger and/or an electrical cooling or heating element, respectively, such as a Peltier cooling element, a resistance heating element, or the like, to achieve rapid response behavior. This enables the exhaust gas testing to be carried out at various exhaust gas temperatures, without changing the measurement structure.

(12) Cooling device 7 and heating device 8 can also be combined in a common temperature changing device.

(13) Furthermore, the exhaust gas can be enriched via the gas metering unit 15 with various gaseous, liquid, or solid reactants 16in the present case CO, NO, NO.sub.2, SO.sub.2, NH.sub.3, HC, or the liketo increase the emission level for relevant exhaust gas components. This improves the quality and informative power of the examination of the exhaust gas after-treatment device 9.

(14) The test stand arrangement 1 enables donor internal combustion engines 2 of different sizes and exhaust gas after-treatment devices 9 of different sizes to be used, wherein only the screens 20, 21 have to be adapted to the respective size of the respective exhaust gas after-treatment device 9. The partial exhaust gas quantity withdrawn from the exhaust gas of the exhaust line 3 can be set exactly via the flow rate setting element 24 and the compressor 6.

(15) A defined exhaust gas partial quantity can thus be withdrawn from the exhaust gas stream of the donor internal combustion engine 2.

(16) It is therefore possible to supply the exhaust gas after-treatment device g or parts thereof to tests and experiments already in very early development phases of an engine development, the results of which can be incorporated into the further development.