Claims:We Claim:
1. An electronic control unit (10) to maintain a temperature in an exhaust system (12) of a vehicle, said control unit (10) adapted to :
- detect a temperature at an upstream (24) of a diesel oxidation catalyst (DOC) (14) during at least one vehicle operating condition, in a regenerative mode ;
- increase a load on an engine (16) of said vehicle, when said detected temperature at said DOC (14) is less than a predefined temperature;
- operate a compressor (18) connected to said engine (16), to increase said load on said engine (16) for a higher combustion temperature in said engine (16);
- maintain said predefined temperature at said upstream (24) of said DOC (14), when said combustion temperature in said engine (16) is increased, due to said compressor load (18).

2. The control unit (10) as claimed in claim 1, further comprises a temperature sensor (20) adapted to sense said temperature at said DOC (14) in said regenerative mode.

3. The control unit (10) as claimed in claim 1, wherein said at least one vehicle operating condition is chosen from any one of the following conditions comprising a low-speed condition and a low-load condition.

4. The control unit (10) as claimed in claim 1, wherein said control unit (10) adapted to inject fuel into said engine (16) to operate said compressor (18) during said at least one vehicle operating condition.

5. The control unit (10) as claimed in claim 4, wherein said fuel is injected into said engine (16) to increase said combustion temperature in said engine (16), to maintain said predefined temperature at said upstream (24) of said DOC (14).

6. A method of maintaining a temperature in an exhaust system (12) of a vehicle, said method comprising :
- detecting a temperature at a diesel oxidation catalyst (DOC) (14), during at least one vehicle operating condition, using a temperature sensor (20) in a regenerative mode;
- increasing a load on an engine (16) of said vehicle, when said detected temperature at said DOC (14) is less than a predefined temperature;
- operating a compressor (18) connected to said engine (16) by an electronic control unit (10), to increase said load on said engine (16) for a higher combustion temperature in said engine (16);
- maintaining said predefined temperature at an upstream (24) of said DOC (14), when said combustion temperature in said engine (16) is increased due to said compressor load (18).

7. The method as claimed in claim 6, injecting fuel into said engine (16) to operate said compressor (18) connected to said engine (16).
, Description:Complete Specification:
The following specification describes and ascertains the nature of this invention and the manner in which it is to be performed.
Field of the invention
[0001] This invention relates to an electronic control unit to maintain a temperature in an exhaust system of a vehicle and a method thereof.

Background of the invention
[0002] From the year 2020 in India, with the implementation of BS6 emission legislation, the diesel particulate filter (DPF) is mandatory for all class of vehicles in order to meet particulate matter number targets. With the current DPF regeneration strategies, it is observed that the catalytic converter light-off temperature (temperature at upstream of the diesel oxidation catalyst) is critically low at low speed and low load conditions. It is seen that the light-off temperatures are very low (<200degC) in low speed/low load zone and therefore the diesel oxidation catalyst does not convert any hydrocarbons being injected in the into the exhaust. Due to the above process, the regeneration is interrupted. It is also observed that with increase in engine capacity (commercial vehicles), the light-off temperatures at the low-speed and low –load conditions, further decreases. To avoid such a scenario, extensive calibration efforts are required to optimize this particular zone (low-speed and low-load) for higher exhaust temperatures.
[0003] A Prior art document US8230679 discloses an internal combustion engine system includes: an engine with a variable load driven by rotary power from the engine, a sensor to provide a sensor signal corresponding to temperature of exhaust from the engine; and a controller coupled to the sensor and operable to regulate a regeneration operation of one or more components of the aftertreatment equipment. The controller responds to the sensor signal to generate one or more control signals to adjust the variable load to increase loading of the engine and correspondingly raise the temperature of the exhaust for the regeneration operation.

Brief description of the accompanying drawing
[0004] Different modes of the invention are disclosed in detail in the description and illustrated in the accompanying drawing:
[0005] Fig.1 illustrates an electronic control unit in a vehicle in accordance with one embodiment of the invention; and
[0006] Fig. 2 illustrates a method of maintaining a temperature in an exhaust system of a vehicle in accordance with one embodiment of the invention.

Detailed description of the embodiments
[0007] Fig.1 illustrates an electronic control unit 10 in a vehicle, in accordance with one embodiment of the invention. The electronic control unit 10 adapted to detect a temperature at upstream of diesel oxidation catalyst (DOC) 14 during at least one vehicle operating condition, in a regenerative mode. The control unit 10 adapted to increase a load on an engine 16 of the vehicle, when the detected temperature at the DOC 14 is less than a predefined temperature. The control unit 10 adapted to operate a compressor connected to the engine 16, to increase the load on the engine 16 for a higher combustion temperature in the engine 16. The control unit 10 adapted to maintain the predefined temperature at upstream 24 of the DOC 14, when the combustion temperature in the engine 16 is increased, due to the compressor load 18.

[0008] Further the construction of the electronic control unit 10 and the exhaust system 12 in a vehicle and the working of the components of the exhaust system 12 are explained below. The electronic control unit 10 further comprises a temperature sensor 20 adapted to detect the temperature upstream 24 of the DOC 14. At least one operating conditions is chosen from any one of the following operating conditions comprising a low-speed condition and a low-load condition. During the regenerative mode, when the vehicle is operating in the low-speed condition or low-load condition, the temperature at upstream 24 of the DOC 14 reduces beyond the predefined temperature, which reduces the conversion process of hydrocarbons (present in the post-injected fuel) into an exothermal energy. To improve the conversion process and to increase a temperature in a diesel particulate filter (DPF) 22 of the exhaust system 12, for a soot oxidization, the electronic control unit 10 maintains the temperature at upstream 24 of DOC 14 above the predefined temperature.

[0009] The connection and working of the engine 16 operating the compressor 18 is known to a person skilled in the art. The compressor 18 disclosed above could be a mechanically operated or an electrically operated compressor. For instance, in the mechanically operated compressor 18, the control unit 10 engages a clutch of the compressor 18 (which is connected to the engine 16) continuously, to increase the load on the engine 16, upon detecting the temperature at upstream 24 of the DOC 14 less than the predefined temperature, during at least one vehicle operating condition. The engaged compressor 18 adapted to compress the atmospheric air and is supplied to a braking system of the vehicle. The control unit 10 connected to engine 16 and to the compressor 18, adapted to control at least one operating condition of the engine 16 and the compressor 18 during the regenerative mode. The control unit 10 adapted to inject fuel into the engine 16 to operate the compressor 18, during the low-load or low-speed condition. The control unit 10 is chosen from a group of control units comprising a microprocessor, a microcontroller, an integrated chip and the like. According to one embodiment of the invention, the electronic control unit 10 is an engine control unit.

[0010] Fig. 2 illustrates a method of maintaining a temperature in an exhaust system of a vehicle according to one embodiment of the invention. In step S1, a temperature at a diesel oxidation catalyst (DOC) 14 during at least one vehicle operating condition, is detected using a temperature sensor 20 in a regenerative mode. In step S2, a load on an engine 16 of the vehicle is increased, when the detected temperature at the upstream 24 of the DOC 14 is less than a predefined temperature. In step S3, a compressor 18 connected to the engine 16 is operated by an electronic control unit 10, to increase the load on the engine for a higher combustion temperature in the engine 16. In step S4, the control unit 10 adapted to inject the fuel into the engine 12 to operate the compressor 18. In step S5, the predefined temperature at upstream 24 of the DOC 14 is maintained, when the combustion temperature in the engine 16 is increased due to the compressor load 18.

[0011] A detailed description of the method of maintaining the temperature in the exhaust system 12 of the vehicle is explained as follows. The regenerative mode is activated in the vehicle for every predefined distance, the vehicle is operated. For instance, the regenerative mode is activated based on the amount of soot loaded in the vehicle. In the regenerative mode, when the vehicle is in the idling or low –speed or low-load condition, the temperature at the upstream 24 of the DOC 14 is reduced, thus reducing the conversion process of hydrocarbons present in the post-injected fuel and further reducing the temperature in the diesel particulate filter (DPF) 22. The control unit 10 upon detecting the temperature at upstream 24 of the DOC 14 being less than the predefined temperature increases the load on the engine 16. According to one embodiment of the invention, the temperature at the upstream 24 of the DOC 14 should be maintained above 220 degrees Celsius, thus the temperature in the DPF 22 reaches to 600 degrees Celsius, which is efficient to oxidize the soot accumulated in the DPF 22.

[0012] when the control unit 10 detects the temperature at upstream 24 of the DOC 14 less than or equal to 220 degrees, then the control unit 10 engages the compressor 18 which is connected to the engine 16. To operate the compressor load 18, the control unit 10 injects the fuel into the engine 16, thus increasing the combustion temperature in the engine 16. Due to the higher combustion temperature in the engine 16, the temperature at the upstream 24 of the DOC 14 increases more than the predefined temperature during the low-load or low-speed condition. (i.e., it increases more than 220 degree Celsius). The control unit 10 engages the compressor 18 until the load on the engine 16 or speed of the engine 16 is increased.

[0013] With the above disclosed method, regeneration process in the vehicle is not interrupted, as DOC 14 upstream temperature is maintained above the predefined temperature which is critical during a city driving condition or where a low speed and a low load driving conditions are prevalent. With the reduction in interruptions in the regeneration process, dependent factors such as oil dilution, increase in the fuel consumption are reduced.

[0014] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims