CLIAMS:We claim:
1. An exhaust gas treatment (EGT) device (10) comprising an EGT substrate (11) located in a housing (12), said housing (12) comprising an inlet flow path (14), an outlet flow path (16) and a bypass path (18) adapted to bypass at least part of the exhaust gases flowing into said EGT substrate, characterized in that
a first valve (20) located in said inlet flow path (14) and adapted to be controlled between plurality of operative positions; and
a second valve (22) located in said outlet flow path (16) and adapted to be controlled between an operative open position and an operative closed position.
2. The EGT device (10) as claimed in claim 1, wherein said first valve (20) located in said inlet flow path (14) in a manner such that the first valve (20) is located at the interface between the inlet flow path (14) and the bypass path (18).
3. The EGT device (10) as claimed in claim 1, wherein said first valve (20) is controlled to be operated in a first operative position, in said first operative position exhaust gases flow through said inlet flow path (14) and through said EGT substrate (11).
4. The EGT device (10) as claimed in claim 1, wherein said first valve (20) is controlled to be operated in a second operative position, in said second operative position exhaust gases flow through said inlet flow path (14) and through said bypass flow path (18).
5. The EGT device (10) as claimed in claim 1, wherein said second valve (22) is controlled to be operated in an operative open position, in said operative open position of said second valve (20) exhaust gases flow out of the EGT substrate (11) flow into said outlet flow path (16).
6. The EGT device (10) as claimed in claim 1, wherein said second valve (22) is controlled to be operated in an operative closed position, in said operative closed position of said second valve (20) exhaust gases flowing through said EGT substrate (11) do not flow to said outlet flow path (16).
7. A method of operating an exhaust gas treatment (EGT) device, said EGT device comprising a first valve (20) located in an inlet flow path (14) and adapted to be controlled between plurality of operative positions and a second valve (22) located in an outlet flow path (16) and adapted to be controlled between an operative open position and an operative closed position, said method comprising the following steps:
- detecting an overrun condition;
- controlling operation of said first valve (20) between plurality of operative positions; and
- controlling operation of said second valve (22) between an operative open position and an operative closed position.
8. An electronic control unit (24) adapted to control operation of an exhaust gas treatment (EGT) device, said EGT device comprising a first valve (20) located in an inlet flow path (14) and adapted to be controlled between plurality of operative positions and a second valve (22) located in an outlet flow path (16) and adapted to be controlled between an operative open position and an operative closed position, said electronic control unit (24) adapted to:
- detect an overrun condition in dependence of information received from a plurality of sensors;
- control operation of said first valve (20) between plurality of operative position in dependence of the information received from a plurality of sensors; and
- control operation of said second valve (22) between an operative open position and an operative closed position in dependence of the information received from a plurality of sensors.
,TagSPECI:Complete specification: The following specification particularly describes the invention and the manner in which it is to be performed.

Field of the invention
[001] This disclosure relates to an exhaust gas treatment device and method of operation thereof.
Background of the invention:
[002] Exhaust gas treatment substrates are commonly used in exhaust systems of vehicles to reduce the amount of pollutants such as un-burnt hydrocarbons, carbon monoxide and smoke. During engine start up, there is relatively low engine temperature which causes improper combustion of air-fuel ratio resulting in emission of large amounts of un-burnt gas components, such as un-burnt hydrocarbons (HC) and the like. Similarly, during overrun condition of the engine when there is no combustion in the engine, fresh air entering the due to natural suction results in the reduction of temperature of the exhaust gases that are sent toward the exhaust gas treatment substrates. This leads to rapid cooling of the exhaust gas treatment substrates. Hence, whenever the substrate activation temperature has not been reached or is reduced like during overrun condition of the engine the substrates cannot significantly lessen un-burnt gas components and thereby resulting in emission of large amounts of un-burnt gases. The temperature at which the catalyst works effectively is known as light off temperature. During overrun condition of the engine the temperature of the EGT components drops drastically. This prevents the EGT components to operate effectively when the injection of the fuel starts again, for example, when the downhill part of the road ends and the user starts pressing the accelerator pedal. This phenomenon also affects soot regeneration in the Diesel Particulate Filter, if the temperature reduces suddenly reduces during regeneration then the regeneration of the EGT substrates will be affected resulting in increased regeneration duration affecting soot burn-off, increasing oil dilution level, reducing fuel efficiency and subject EGT to thermal stresses.
[003] A published US patent document US2013/0167509 discloses a device and method for supplying high temperature exhaust gases to an EGT substrate. A bypass valve is provided such that the air supplied to the turbine of the turbocharger is reduced by bypassing the exhaust gases flowing through the turbine. Since the exhaust gases bypass the turbine the reduction in temperature of the exhaust gases entering the EGT substrate. This ensures that the EGT substrate is kept active.

Brief description of the accompanying drawings:
[004] An embodiment of the disclosure is described with reference to the following accompanying drawings;
[005] Figure 1 illustrates a schematic block diagram of the exhaust gas treatment device located along the exhaust gas flow path.
Detailed description of the embodiments:
[006] Figure 1 illustrates a schematic block diagram of the exhaust gas treatment device located along the exhaust gas flow path. The exhaust gas treatment (EGT) device 10 comprises an EGT substrate 11(here EGT comprises of two different substrates: Diesel Oxidation Catalyst and Diesel particulate Filter) located in a housing 12. The housing 12 comprises an inlet flow path 14, an outlet flow path 16 and a bypass path 18 adapted to bypass at least part of the exhaust gases flowing into the EGT substrate 11. The EGT device 10 is characterized such that a first valve 20 located in the inlet flow path 14 and adapted to be controlled between plurality of operative positions and a second valve 22 located in outlet flow path 16 and adapted to be controlled between an operative open position and an operative closed position. The EGT device is located downstream from an engine 1.
[007] The construction of the EGT device 10 and the components of the EGT device 10 can be explained as follows. The first valve 20 located in the inlet flow path 14 in a manner such that the first valve 20 is located at the interface between the inlet flow path 14 and the bypass path 18. The second valve 22 is located in the outlet flow path 20 downstream from the housing 12 in which the EGT substrate 11 is located. The first valve 20 is controlled to be operated in a first operative position, in the first operative position exhaust gases flow through the inlet flow path 14 and through the EGT substrate 11. The first valve 20 is controlled to be operated in a second operative position, in the second operative position exhaust gases flow through the inlet flow path 14 and through the bypass flow path 18.
[008] The second valve 22 is controlled to be operated in an operative open position, in the operative open position of the second valve 20 exhaust gases flow out of the EGT substrate 11 flow into the outlet flow path 16. The second valve 22 is controlled to be operated in an operative closed position, in the operative closed position of the second valve 20 exhaust gases flowing through the EGT substrate 11 do not flow to the outlet flow path 16.
[009] An electronic control unit 24 is adapted to control operation of an exhaust gas treatment (EGT) device. The EGT device 10 comprising a first valve 20 is located in an inlet flow path 14 and adapted to be controlled between plurality of operative positions and a second valve 22 located in an outlet flow path 16 and adapted to be controlled between an operative open position and an operative closed position. The electronic control unit 24 adapted to: detect an overrun condition in dependence of information received from a plurality of sensors; control operation of the first valve 20 between plurality of operative position in dependence of the information received from a plurality of sensors; and control operation of the second valve 22 between an operative open position and an operative closed position in dependence of the information received from a plurality of sensors.

[0010] A method of operating the exhaust gas treatment EGT device is also disclosed. The EGT device comprises a first valve 20 is located in an inlet flow path 14 and adapted to be controlled between plurality of operative positions and a second valve 22 is located in an outlet flow path 16 and adapted to be controlled between an operative open position and an operative closed position. The method comprises the following step: detecting an overrun condition; controlling operation of the first valve 20 between plurality of operative positions; and controlling operation of said second valve 22 between an operative open position and an operative closed position.
[0011] The method of operating the EGT device 10 will be further explained in detail. The EGT device 10 is located downstream of an engine 1 as seen in figure 1, the EGT device 10 is located in the exhaust gas flow path of the engine. For the ease of understanding the working of the EGT device 10 two operating modes of the engine need to defined. A first operating mode of the engine is an operating mode wherein a driver demands exists to increase the speed of the engine by pressing the accelerator pedal. A second operating mode of the engine is an operating mode wherein there is demand from the driver; this second operating mode is known as the overrun condition. Overrun is a condition where vehicle inertia will be driving the engine and no injections and there will be no in-cylinder combustion.
[0012] The method of operation the EGT device 10 in accordance with this disclosure happens as follows. During the first operating mode of the engine the first valve 20 is maintained in a first operative position and the second valve 22 is maintained in the operative open position. In the first operative position of the first valve 22 and the operative open position of the second valve 22, the exhaust gases flow from the engine 1 towards to the inlet flow path 14, through the first valve 20, through the EGT substrate 11, through the second valve 22 and to the outlet flow path 16 of the EGT device 10. When a second operating mode i.e. overrun condition of the engine occurs, an electronic control unit detects that the engine is operating the overrun condition.
[0013] When the overrun condition is detected by the electronic control unit, the electronic control unit actuates the first valve 20 and the second valve 22. The first valve 20 is actuated such that first valve 20 is switched from a first operative position to a second operative position and the second valve 22 is actuated such that second valve 22 is switched from a operative open position to an operative closed position. In the second operative position of the first valve 20, the exhaust gases entering the EGT device 10 are directed from the inlet flow path 14 towards the bypass flow path 18. In the operative closed position of the second valve the exhaust gases which have already entered the EGT substrate are not allowed to escape to the outlet flow path 16 of the EGT device 10. Thus no gases enter or leave the EGT device 10, this ensures that the temperature of the EGT substrates 11 are maintained at the same level. Since the substrates are maintained at a constant level, there is no reduction in the temperature of the substrates. Thus when the engine is operated from an overrun condition to a normal operating condition, the temperature of the EGT substrates 11 is maintained such that regeneration of the EGT substrates 11 is done efficiently. Since the EGT substrates are maintained at a constant temperature, there is no delay in activating the substrates, this also ensures that exhaust gas emissions are kept under check. Thus when the engine is working in normal operating condition, the electronic control unit actuates the first valve 20 and the second valve 22. The electronic control unit actuates the first valve 20 and the first valve switches from the second operative position to the first operative position. The electronic control unit actuates the second valve 22 and the second valve 22 switches from the operative closed position to the operative open position.
[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.

CLAIMS
We claim:
1. An exhaust gas treatment (EGT) device (10) comprising an EGT substrate (11) located in a housing (12), said housing (12) comprising an inlet flow path (14), an outlet flow path (16) and a bypass path (18) adapted to bypass at least part of the exhaust gases flowing into said EGT substrate, characterized in that
a first valve (20) located in said inlet flow path (14) and adapted to be controlled between plurality of operative positions; and
a second valve (22) located in said outlet flow path (16) and adapted to be controlled between an operative open position and an operative closed position.
2. The EGT device (10) as claimed in claim 1, wherein said first valve (20) located in said inlet flow path (14) in a manner such that the first valve (20) is located at the interface between the inlet flow path (14) and the bypass path (18).
3. The EGT device (10) as claimed in claim 1, wherein said first valve (20) is controlled to be operated in a first operative position, in said first operative position exhaust gases flow through said inlet flow path (14) and through said EGT substrate (11).
4. The EGT device (10) as claimed in claim 1, wherein said first valve (20) is controlled to be operated in a second operative position, in said second operative position exhaust gases flow through said inlet flow path (14) and through said bypass flow path (18).
5. The EGT device (10) as claimed in claim 1, wherein said second valve (22) is controlled to be operated in an operative open position, in said operative open position of said second valve (20) exhaust gases flow out of the EGT substrate (11) flow into said outlet flow path (16).
6. The EGT device (10) as claimed in claim 1, wherein said second valve (22) is controlled to be operated in an operative closed position, in said operative closed position of said second valve (20) exhaust gases flowing through said EGT substrate (11) do not flow to said outlet flow path (16).
7. A method of operating an exhaust gas treatment (EGT) device, said EGT device comprising a first valve (20) located in an inlet flow path (14) and adapted to be controlled between plurality of operative positions and a second valve (22) located in an outlet flow path (16) and adapted to be controlled between an operative open position and an operative closed position, said method comprising the following steps:
- detecting an overrun condition;
- controlling operation of said first valve (20) between plurality of operative positions; and
- controlling operation of said second valve (22) between an operative open position and an operative closed position.
8. An electronic control unit (24) adapted to control operation of an exhaust gas treatment (EGT) device, said EGT device comprising a first valve (20) located in an inlet flow path (14) and adapted to be controlled between plurality of operative positions and a second valve (22) located in an outlet flow path (16) and adapted to be controlled between an operative open position and an operative closed position, said electronic control unit (24) adapted to:
- detect an overrun condition in dependence of information received from a plurality of sensors;
- control operation of said first valve (20) between plurality of operative position in dependence of the information received from a plurality of sensors; and
- control operation of said second valve (22) between an operative open position and an operative closed position in dependence of the information received from a plurality of sensors.

Dated this 31st day of March, 2015
(Digitally signed)
Kartik PuttAiah
Patent agent of the Applicants (IN/PA-1809)

ABSTRACT
An exhaust gas treatment (EGT) device and a method of operating the EGT device is disclosed. The exhaust gas treatment (EGT) device 10 comprises an EGT substrate 11 located in a housing 12. The housing 12 comprises an inlet flow path 14, an outlet flow path 16 and a bypass path 18 adapted to bypass at least part of the exhaust gases flowing into the EGT substrate. The EGT device is characterized such that a first valve 20 located in the inlet flow path 14 and adapted to be controlled between plurality of operative positions and a second valve 22 located in outlet flow path 16 and adapted to be controlled between an operative open position and an operative closed position.
Figure 1