METHOD FOR OPERATING A DRIVE DEVICE AND CORRESPONDING DRIVE DEVICE

Abstract

The invention relates to a method for operating a drive device that, for purifying of exhaust gas, comprises at least one catalytic converter having an oxygen storage. wherein upstream of the catalyst a pre-catalyst molecular mass of a first substance, and a pre-catalyst molecular mass of oxygen is determined. According to the invention, in order to calculate a post-catalytic converter lambda value, a post-catalytic converter oxygen molecular mass is determined by considering the reaction equation for the reaction of the oxygen with the first substance, and, in order to determine the post-catalytic converter oxygen molecular mass, a second reaction equation that describes a reaction of the first substance with the oxygen stored in the oxygen storage, and a third reaction equation that describes the introduction of oxygen from the exhaust gas into the oxygen storage are additionally considered, wherein a fill level of the oxygen storage is entered in a reaction rate of the second reaction equation and in a reaction rate of the third reaction equation. The invention further relates to a drive device

Claims

1. Method for operating a drive device, which for purifying exhaust gas has a catalytic converter with an oxygen accumulator, wherein upstream of the catalytic converter a pre catalytic converter molecular mass of a first substance and a pre catalytic converter oxygen molecular mass of oxygen, wherein for calculating a post catalytic converter lambda value a post catalytic converter oxygen molecular mass is determined in that by means of a first reaction equation the reaction of the oxygen with the first substance is taken into account and that in the determination of the post catalytic converter oxygen molecular mass additionally a second reaction equation which describes a reaction of the first substance with the oxygen stored in the oxygen accumulator, and a third reaction equation which describes the introduction of oxygen form the exhaust gas into the oxygen accumulator are taken into account, wherein a load state of the oxygen accumulator factors into a reaction speed of the second reaction equation and a reaction speed of the third reaction equation, characterized in that as second reaction equation
M.sub.2+O.sub.2,sp.fwdarw.M.sub.2O is used, wherein the reaction speed for the second reaction equation is $k_{M_{2,}.Math.O_{2,\mathrm{sp}}}\left(T,\mathrm{OSC},\mathrm{ROL}\right)=y_{M_2}.Math.\mathrm{OSC}.Math.\frac{k_{{\mathrm{ROL}}_{M_2}}.Math.\mathrm{ROL}}{1+k_{{\mathrm{ROL}}_{M_2}}.Math.\mathrm{ROL}}.Math.k_{M_2,O_{2,\mathrm{sp}}}^{300.Math..Math..Math.C.}.Math.e^{\frac{E_{M_2,O_{2,\mathrm{sp}}}}{R}.Math.\left(\frac{1}{T}-\frac{1}{573.15.Math.K}\right)},$ wherein M stands for the first substance, y for the partial pressure, k for the reaction speed prevailing at standard ambient conditions, E for the activation energy of the reaction equation, R for the universal gas constant, T for the absolute temperature of the exhaust gas, O.sub.2,sp for the molecular oxygen present in the oxygen accumulator, OSC for the storage capacity of the catalytic converter, ROL of the relative load state of the oxygen accumulator and k.sub.ROL of the influence of the availability of the oxygen stored in the oxygen storage on the reaction, and or that as third reaction equation
O.sub.2.fwdarw.O.sub.2,sp is used, wherein the reaction speed for the third reaction equation is $k_{O_{2,}.Math.O_{2,\mathrm{sp}}}\left(T,\mathrm{OSC},\mathrm{ROL}\right)=y_{O_2}.Math.\mathrm{OSC}.Math.\frac{k_{{\mathrm{ROL}}_{O_2}}.Math.\left(1-\mathrm{ROL}\right)}{1+k_{{\mathrm{ROL}}_{O_2}}.Math.\left(1-\mathrm{ROL}\right)}.Math.k_{O_2,O_{2,\mathrm{sp}}}^{300.Math..Math..Math.C.}.Math.e^{\frac{E_{O_2,O_{2,\mathrm{sp}}}}{R}.Math.\left(\frac{1}{T}-\frac{1}{573.15.Math.K}\right)},$ wherein M stands for the first substance, y for the partial pressure, k for the reaction speed prevailing under standard ambient conditions, E for the activation energy of the reaction equation, R for the universal gas constant, T for the absolute temperature of the exhaust gas, O.sub.2,sp for the molecular oxygen present in the oxygen accumulator, OSC for the storage capacity of the catalytic converter, ROL for the relative load state of the oxygen accumulator and k.sub.ROL for the influence of the availability of the oxygen stored in the oxygen accumulator on the reaction.

2. Method according to claim 1 characterized in that as first reaction equation
M.sub.2+O.sub.2.fwdarw.M.sub.2O is used, wherein a reaction speed of the first reaction equation is $k_{M_{2,}.Math.O_2}\left(T\right)=y_{M_2}.Math.y_{O_2}.Math.k_{M_2,O_2}^{300.Math..Math..Math.C.}.Math.e^{\frac{E_{M_2,O_2}}{R}.Math.\left(\frac{1}{T}-\frac{1}{573.15.Math.K}\right)}.$

3. Method according to one of the preceding claims, characterized in that in addition a fourth reaction equation is taken into account, which describes the influence of the stored oxygen on a reaction of water contained in the exhaust gas with a second substance, wherein the load state of the oxygen accumulator factors into a reaction speed of the fourth reaction equation.

4. Method according to one of the preceding claims, characterized in that as fourth reaction equation
H.sub.2O.fwdarw.H.sub.2+O.sub.2,sp Is used, wherein the reaction speed for the fourth reaction equation is $k_{H_2.Math.O,O_{2,\mathrm{sp}}}\left(T,\mathrm{OSC},\mathrm{ROL}\right)=y_{H_2.Math.O}.Math.\mathrm{OSC}.Math.\frac{1}{1+k_{{\mathrm{ROL}}_{H_2.Math.O}}.Math.\left(1-\mathrm{ROL}\right)}.Math.k_{H_2.Math.O,O_{2,\mathrm{sp}}}^{300.Math..Math..Math.C.}.Math.e^{\frac{E_{H_2.Math.O,O_{2,\mathrm{sp}}}}{R}.Math.\left(\frac{1}{T}-\frac{1}{573.15.Math.K}\right)}.$

5. Method according to one of the preceding claims, characterized in that in addition a fifth reaction equation is taken into account which describes the efflux of stored oxygen into the exhaust gas, wherein the load state of the oxygen accumulator factors into a reaction speed of the fifth reaction equation.

6. Method according to one of the preceding claims, characterized in that as fifth reaction equation
O.sub.2,sp.fwdarw.O.sub.2 is used, wherein the reaction speed for the fifth reaction equation is $k_{O_{2,\mathrm{sp},}.Math.O_2}\left(T,\mathrm{OSC},\mathrm{ROL}\right)=\mathrm{OSC}.Math.\frac{1}{1+k_{{\mathrm{ROL}}_{O_2}}.Math.\left(1-\mathrm{ROL}\right)}.Math.k_{O_{2,\mathrm{sp}},O_2}^{300.Math..Math..Math.C.}.Math.e^{\frac{E_{O_{2,\mathrm{sp}},O_2}}{R}.Math.\left(\frac{1}{T}-\frac{1}{573.15.Math.K}\right)}.$

7. Method according to one of the preceding claims, characterized in that the load state is determined by at least one reaction equation by integrating, wherein the at least one reaction equation is selected from the second reaction equation, the third reaction equation, the fourth reaction equation and the fifth reaction equation.

8. Drive device, in particular for implementing the method according to one or more of the preceding claims, wherein the drive device has at least one catalytic converter with an oxygen accumulator for purifying exhaust gas, wherein it is provided to determine upstream of the catalytic converter a pre catalytic converter molecular mass of a first substance and a pre catalytic converter oxygen molecular mass of oxygen, wherein the drive device is configured to determine a post catalytic converter oxygen molecular mass for calculating a post catalytic converter lambda value, in that by means of a first reaction equation the reaction of the oxygen with the first substance is taken into account, and that in the determining of the post catalytic converter oxygen molecular mass additionally a second reaction equation which describes a reaction of the first substance with the oxygen in the oxygen accumulator and a third reaction equation which describes the introduction of oxygen form the exhaust gas into the oxygen accumulator are taken into account, wherein the load state of the oxygen accumulator factors onto a reaction speed of the second reaction equation and a reaction speed of the third reaction equation, characterized in that as
M.sub.2+O.sub.2,sp.fwdarw.M.sub.2O is used, wherein the reaction speed for the second reaction equation is $k_{M_{2,}.Math.O_{2,\mathrm{sp}}}\left(T,\mathrm{OSC},\mathrm{ROL}\right)=y_{M_2}.Math.\mathrm{OSC}.Math.\frac{k_{{\mathrm{ROL}}_{M_2}}.Math.\mathrm{ROL}}{1+k_{{\mathrm{ROL}}_{M_2}}.Math.\mathrm{ROL}}.Math.k_{M_2,O_{2,\mathrm{sp}}}^{300.Math..Math..Math.C.}.Math.e^{\frac{E_{M_2,O_{2,\mathrm{sp}}}}{R}.Math.\left(\frac{1}{T}-\frac{1}{573.15.Math.K}\right)},$ wherein M stands for the first substance, y for the partial pressure, k for the reaction speed prevailing at standard ambient conditions, E for the activation energy of the reaction equation, R for the universal gas constant, T for the absolute temperature of the exhaust gas, O.sub.2,sp for the molecular oxygen present in the oxygen accumulator, OSC for the storage capacity of the catalytic converter, ROL of the relative load state of the oxygen accumulator and k.sub.ROL of the influence of the availability of the oxygen stored in the oxygen storage on the reaction, and or that as third reaction equation
O.sub.2.fwdarw.O.sub.2,sp is used, wherein the reaction speed for the third reaction equation is $k_{O_{2,}.Math.O_{2,\mathrm{sp}}}\left(T,\mathrm{OSC},\mathrm{ROL}\right)=y_{O_2}.Math.\mathrm{OSC}.Math.\frac{k_{{\mathrm{ROL}}_{O_2}}.Math.\left(1-\mathrm{ROL}\right)}{1+k_{{\mathrm{ROL}}_{O_2}}.Math.\left(1-\mathrm{ROL}\right)}.Math.k_{O_2,O_{2,\mathrm{sp}}}^{300.Math..Math..Math.C.}.Math.e^{\frac{E_{O_2,O_{2,\mathrm{sp}}}}{R}.Math.\left(\frac{1}{T}-\frac{1}{573.15.Math.K}\right)},$ wherein M stands for the first substance, y for the partial pressure, k for the reaction speed prevailing under standard ambient conditions, E for the activation energy of the reaction equation, R for the universal gas constant, T for the absolute temperature of the exhaust gas, O.sub.2,sp for the molecular oxygen present in the oxygen accumulator, OSC for the storage capacity of the catalytic converter, ROL for the relative load state of the oxygen accumulator and k.sub.ROL for the influence of the availability of the oxygen stored in the oxygen accumulator on the reaction.

Description

[0035] In the following the invention is described in more detail with reference to the exemplary embodiments shown in the drawing, without limiting the invention. Hereby it is shown in:

[0036] FIG. 1 diagrams in which a pre catalytic converter lambda value, a determined and an actual post catalytic converter lambda value, a pre catalytic converter molecular mass of a first substance, a pre catalytic converter oxygen molecular mass, a post catalytic converter molecular mass of the first substance and a post catalytic converter oxygen molecular mass and a load state of an oxygen accumulator of a catalytic converter are plotted over time, wherein only a first reaction equation is taken into account,

[0037] FIG. 2 a diagram in which reaction speeds of a second and a third reaction equation are shown,

[0038] FIG. 3 diagrams which show values analogous to FIG. 1, wherein in addition the second reaction equation and the third reaction equation are taken into account,

[0039] FIG. 4 a diagram in which reaction speeds for the second, the third and a fourth reaction equation are shown,

[0040] FIG. 5 diagrams which show values analogous to FIG. 1, wherein in addition a fourth reaction equation is taken into account,

[0041] FIG. 6 a diagram in which reaction speeds for the second reaction equation, the third reaction equation, the fourth reaction equation and a fifth reaction equation are shown plotted over the load state of the oxygen accumulator, and

[0042] FIG. 7 diagrams, which show values in analogy to FIG. 1, wherein in addition the fifth reaction equation is taken into account.

[0043] FIG. 1 shows multiple diagrams in which a course 1 describes a pre catalytic converter lambda value and course 2 describes a post catalytic converter lambda value over time t. A second diagram shows courses 3, 4, 5 and 6 over the time t. The course 3 describes a pre catalytic converter oxygen molecular mass, the course 4 a pre catalytic converter molecular mass of a first substance, the course 5 a post catalytic converter oxygen molecular mass and the course 6 a post catalytic converter molecular mass of the first substance. Finally the third diagram shows a course 7, which represents a filing level of an oxygen accumulator of a catalytic converter over the time t. the course 2 is hereby determined by way of the first reaction equation and the corresponding reaction speed described above.

[0044] FIG. 2 shows a diagram in which a course 8 shows a reaction speed of a second reaction equation on dependence on the load state of the oxygen accumulator. The course 9 on the other hand shows the reaction speed of a fourth reaction equation also over the load state.

[0045] FIG. 3 shows diagrams analogous to those of FIG. 1, wherein the here shown values however were determined by way of the first reaction equation, the second reaction equation and the third reaction equation, respectively with the corresponding reaction speeds. The additional course 2 represents the actually present post catalytic converter lambda value. It can be seen that the modeled post catalytic converter lambda value, which is described by the course 2, is already significantly closer to the actual course 2 than was the case in FIG. 1.

[0046] The diagram of FIG. 4 shows beside the courses 8 and 9, as they are already known from FIG. 2, a course 10. This course described the reaction speed of a fourth reaction equation over the load state of the oxygen accumulator. The fourth reaction equation essentially represents a water-gas-shift-equation.

[0047] The diagrams shown in FIG. 5 correspond to those shown in FIGS. 1 and 3, wherein the values shown therein, however, were determined by way of the reaction equations 1 to 4. A further improvement of the results compared to those of FIG. 3 can be seen.

[0048] FIG. 6 shows a diagram, which again shows the courses 8, 9 and 10. In addition a course 11 is shown which represents the reaction speeds of a fifth reaction equation. The fifth reaction equation describes the transition of oxygen form the oxygen accumulator into the exhaust gas.

[0049] The results when taking the reaction equations 1 to 5 into account are shown in FIG. 7. It can be seen that the course 2 corresponds to the course 2. This means that by taking the reaction equations 1 to 5 into account for modeling the post catalytic converter oxygen molecular mass and thus in the calculation of the post catalytic converter lambda value, results are achieved that reflect the theoretical results with good accuracy.

LIST OF REFERENCE SIGNS

[0050] 1 course [0051] 2 course [0052] 3 course [0053] 4 course [0054] 5 course [0055] 6 course [0056] 7 course [0057] 8 course [0058] 9 course [0059] 10 course [0060] 11 course