초록 ▼

A method is provided for operating an internal combustion engine in whose exhaust-gas region an exhaust-gas treatment device is situated, and in which a reagent is introduced into the exhaust-gas region of the internal combustion engine. in addition, a device is provided for implementing the method.

A method is provided for operating an internal combustion engine in whose exhaust-gas region an exhaust-gas treatment device is situated, and in which a reagent is introduced into the exhaust-gas region of the internal combustion engine. in addition, a device is provided for implementing the method. The reagent pressure occurring between a reagent safety valve and a reagent dosing valve, disposed directly in the exhaust-gas region is recorded during different states of the reagent safety valve and/or the reagent dosing valve and compared to at least one threshold value. If the threshold is exceeded, a fault signal is provided. This may offer high safety which may be of particular importance when fuel is used as reagent.

대표청구항 ▼

What is claimed is: 1. A method for operating an internal combustion engine in whose exhaust-gas region an exhaust-gas treatment device is situated, comprising: introducing a reagent into the exhaust-gas region upstream in front of the exhaust-treatment device; immediately and directly spraying the

What is claimed is: 1. A method for operating an internal combustion engine in whose exhaust-gas region an exhaust-gas treatment device is situated, comprising: introducing a reagent into the exhaust-gas region upstream in front of the exhaust-treatment device; immediately and directly spraying the reagent into the exhaust-gas region, wherein in a flow direction of the reagent, which is brought to a predefined reagent source pressure, a switchable reagent safety valve is arranged first and then a continuous reagent dosing valve, the reagent dosing valve being disposed in the exhaust-gas region; recording a reagent pressure in a reagent path, the reagent path being between the reagent safety valve and the reagent dosing valve; comparing the reagent pressure detected in at least one predefined state of at least one of the reagent safety valve, and the reagent dosing valve, to at least one threshold value, wherein the comparing step includes: a first checking step including checking whether the reagent pressure is just below the reagent source pressure, minus a pressure drop at the reagent safety valve when the reagent safety valve and the reagent dosing valve are open simultaneously; and a second checking step including checking whether the reagent pressure is above an exhaust-gas pressure and below the reagent source pressure, minus the pressure drop at the reagent safety valve following a closing of the reagent safety valve subsequent to the first checking step and a closing of the reagent dosing valve subsequent to the first checking step; and providing a fault signal in case of a threshold exceedance. 2. The method as recited in claim 1, wherein the comparing step further includes a third step including checking whether the reagent pressure is below the reagent source pressure minus a pressure drop at the reagent safety valve when the reagent safety valve and the reagent dosing valve are closed. 3. The method as recited in claim 1, further comprising: checking whether the reagent pressure drop does not exceed a predefined pressure gradient. 4. The method as recited in claim 1, wherein the comparing step further includes a third checking step including checking whether the reagent pressure exhibits at least an exhaust-gas pressure when the reagent safety valve and the reagent dosing valve are closed. 5. The method as recited in claim 4, wherein the comparing step further includes a fourth checking step including checking whether the reagent pressure corresponds at least approximately to the reagent source pressure following an opening of the reagent safety valve subsequent to the third checking step. 6. The method as recited in claim 5, wherein the comparing step further includes a fifth checking step including checking whether the reagent pressure has at least the exhaust-gas pressure following a closing of the reagent safety valve subsequent to the fourth checking step and an opening of the reagent dosing valve subsequent to the closing, subsequent to the fourth checking step, of the reagent safety valve. 7. The method as recited in claim 5, wherein the comparing step further includes a fifth checking step including checking whether the reagent pressure continues to correspond at least approximately to the reagent source pressure following a closing of the reagent safety valve subsequent to the fourth checking step. 8. The method as recited in claim 7, wherein the comparing step further includes a sixth checking step including checking whether the reagent pressure has at least the exhaust-gas pressure following a closing of the reagent safety valve subsequent to the fifth checking step and an opening of the reagent dosing valve subsequent to the closing, subsequent to the fifth checking step, of the reagent safety valve. 9. The method as recited in claim 8, wherein the fourth checking step is performed following the third checking step, the fifth checking step is performed following the fourth checking step, the sixth checking step is performed following the fifth checking step, the first checking step is performed following the sixth checking step, and the second checking step is performed following the first checking step. 10. The method as recited in claim 9, wherein the third checking step further includes checking whether the reagent pressure is below the reagent source pressure minus a pressure drop at the reagent safety valve when the reagent safety valve and the reagent dosing valve are closed. 11. The method as recited in claim 10, further comprising: following the second checking step, checking whether the reagent pressure drop does not exceed a predefined pressure gradient. 12. A device for operating an internal combustion engine having an exhaust-gas region, an exhaust-gas treatment device being situated in the exhaust-gas region, the device comprising: a control unit configured to control the following steps: introducing a reagent into the exhaust-gas region upstream in front of the exhaust-treatment device; immediately and directly spraying the reagent into the exhaust-gas region, wherein in a flow direction of the reagent, which is brought to a predefined reagent source pressure, a switchable reagent safety valve is arranged first and then a continuous reagent dosing valve, the reagent dosing valve being disposed in the exhaust-gas region; recording a reagent pressure in a reagent path, the reagent path being between the reagent safety valve and the reagent dosing valve; comparing the reagent pressure detected in at least one predefined state of at least one of the reagent safety valve, and the reagent dosing valve, to at least one threshold value, wherein the comparing step includes: a first checking step including checking whether the reagent pressure is just below the reagent source pressure, minus a pressure drop at the reagent safety valve when the reagent safety valve and the reagent dosing valve are open simultaneously; and a second checking step including checking whether the reagent pressure is above an exhaust-gas pressure and below the reagent source pressure, minus the pressure drop at the reagent safety valve following a closing of the reagent safety valve subsequent to the first checking step and a closing of the reagent dosing valve subsequent to the first checking step; and providing a fault signal in case of a threshold exceedance. 13. The device as recited in claim 12, wherein the control unit includes a diagnostic controller, a threshold value selection and a comparator for comparing the reagent pressure to at least one threshold value.