Field of the invention
[0001] This invention relates to a diesel particulate filter and more specifically to a
method for correcting a pressure differential across a new diesel particulate filter.
Background of the invention
[0002] JP 2005214084 A - To prevent a DPF (Diesel Particulate Filter) from being damaged. This regenerative apparatus for the particulate filter comprises the DPF, an inlet side pressure lead-in pipe and an outlet side pressure lead-in pipe for leading pressures at the inlet and outlet sides of the DPF, pressure differential sensors connected to the inlet side pressure lead-in pipe and the outlet side pressure lead-in pipe and detecting a pressure difference (a pressure difference across the filter) between the inlet side and the outlet side of the DPF, and temperature sensors as a lead-in exhaust gas flow determination means for determining whether an exhaust gas flow occurs in the pressure lead-in pipes or not. When the exhaust gas flow is determined to occur in at least either of the inlet side pressure lead-in pipe and the outlet side pressure lead-in pipe, the DPF is regenerated when the collected amount of exhaust particulates collected in the DPF is calculated when the pressure difference across the DPF reaches a pre-set specified amount.
Brief description of the accompanying drawing
[0003] Figure 1 illustrates a flow chart indicating a method for correcting a pressure
differential across a new diesel particulate filter.
Detailed description of the embodiments
[0004] Figure 1 illustrates a method to correct a differential pressure across a new diesel particulate filter. The method comprises sensing a differential pressure of exhaust gas between an exhaust gas inlet pipe and an exhaust gas outlet pipe that are each secured to a diesel particulate filter, by means of a differential pressure sensor at

a predetermined time interval. The method further comprises comparing the differential pressure of exhaust gas that exists between the fuel inlet pipe and the fuel outlet pipe with a predetermined differential pressure of exhaust gas that is stored within a memory unit, and offsetting the differential pressure of exhaust gas that exists between the fuel inlet pipe and the fuel outlet pipe to a zero value if the differential pressure of exhaust gas that exists between the fuel inlet pipe and the fuel outlet pipe is one of greater or lesser than the predetermined differential pressure of exhaust gas that is stored within the memory unit.
[0005] The method 10 to correct a differential pressure across a new diesel particulate filter comprises securing an exhaust gas inlet pipe and an exhaust gas outlet pipe to a diesel particulate filter. The exhaust gas that flows through the diesel particulate filter via the exhaust gas inlet pipe is channeled into the exhaust gas outlet pipe after the soot particles from the exhaust gas are captured by the diesel particulate filter. A differential pressure sensor is secured between the exhaust gas inlet pipe and the exhaust gas outlet pipe of the diesel particulate filter and senses a differential pressure of exhaust gas that exists between the exhaust gas inlet pipe and the exhaust gas outlet pipe. The differential pressure of exhaust gas between the exhaust gas inlet pipe and the exhaust gas outlet pipe is sensed by the differential pressure sensor at a predetermined time interval. More specifically, the differential pressure of exhaust gas between the fuel inlet pipe and the fuel outlet pipe is sensed by the differential pressure sensor from the time the diesel particulate filter is installed until a predetermined interval of time e.g. 50 kilometers from the time of installation of the diesel particulate filter.
[0006] Once the differential pressure of exhaust gas between the fuel inlet pipe and the fuel outlet pipe is sensed by the differential pressure sensor, the differential pressure of exhaust gas that exists between the fuel inlet pipe and the fuel outlet pipe

is compared with a predetermined differential pressure of exhaust gas that is stored within a memory unit. The predetermined differential pressure of exhaust gas that is stored within the memory unit is preprogrammed by the user before the diesel particulate filter is installed. The method further comprises offsetting the pressure differential of exhaust gas that exists between the fuel inlet pipe and the fuel outlet pipe to a zero value if the pressure differential of exhaust gas that exists between the fuel inlet pipe and the fuel outlet pipe is one of greater or lesser than the predetermined pressure differential of exhaust gas that is stored within a memory unit. If the pressure differential of exhaust gas that exists between the fuel inlet pipe and the fuel outlet pipe is equal to the predetermined pressure differential of exhaust gas that is stored within the memory unit, the pressure differential of exhaust gas that exists between the fuel inlet pipe and the fuel outlet pipe is set to be equal to zero.
[0007] The method to correct a differential pressure for a new diesel particulate filter is described with reference to Figure 1. The method 10 comprises determining 20 a delta pressure between an exhaust gas inlet pipe and an exhaust gas outlet pipe of an empty diesel particulate filter when it has been newly installed by an engine control unit. Therein, a theoretical value of delta pressure between the exhaust gas inlet pipe and the exhaust gas outlet pipe of an empty diesel particulate filter when it has been newly installed is retrieved from a data map 40 by the engine control unit. The engine control unit then compares 60 the delta pressure between the exhaust gas inlet pipe and the exhaust gas outlet pipe of the empty diesel particulate filter when it has been newly installed with the theoretical value of delta pressure between the exhaust gas inlet pipe and the exhaust gas outlet pipe of an empty diesel particulate filter when it has been newly installed from the retrieved data map 40.
[0008] If the delta pressure between the exhaust gas inlet pipe and the exhaust gas outlet pipe of the empty diesel particulate filter when it has been newly installed is

equal to the theoretical value of delta pressure between the exhaust gas inlet pipe and the exhaust gas outlet pipe of an empty diesel particulate filter when it has been newly installed from the data map 40, the actual value 65 of the diesel particulate filter pressure is set to be the new value 75 of delta pressure between the exhaust gas inlet pipe and the exhaust gas outlet pipe of an empty diesel particulate filter when it has been newly installed. If the delta pressure between the exhaust gas inlet pipe and the exhaust gas outlet pipe of the empty diesel particulate filter when it has been newly installed is not equal to the theoretical value of delta pressure between the exhaust gas inlet pipe and the exhaust gas outlet pipe of an empty diesel particulate filter when it has been newly installed from the data map 40, the data map 40 is updated 80 with the value of the delta pressure between the exhaust gas inlet pipe and the exhaust gas outlet pipe of the empty diesel particulate filter when it has been newly installed. Therein, the actual value of the diesel particulate filter pressure is set to be the new value 75 of the delta pressure between the exhaust gas inlet pipe and the exhaust gas outlet pipe of the empty diesel particulate filter when it has been newly installed.
[0009] At the beginning 90 of the actual soot load estimation, the differential pressure 92 between the exhaust gas inlet pipe and the exhaust gas outlet pipe is measured. This measured differential pressure between the exhaust gas inlet pipe and the exhaust gas outlet pipe is subtracted 94 from the differential pressure across the diesel particulate filter when the diesel particulate filter is empty at the beginning of the installation of the diesel particulate filter. The difference between the measured differential pressure between the exhaust gas inlet pipe and the exhaust gas outlet pipe and the differential pressure across the diesel particulate filter when the diesel particulate filter is empty at the beginning of the installation of the diesel particulate filter is equal to the differential pressure 98 caused due to soot accumulation in the diesel particulate filter. As the soot continues to accumulate in the diesel particulate filter, the difference between the measured differential pressure between the exhaust gas inlet pipe and the

exhaust gas outlet pipe and the differential pressure across the diesel particulate filter when the diesel particulate filter is empty at the beginning of the installation of the diesel particulate filter continues to increase. When the difference between the measured differential pressure between the exhaust gas inlet pipe and the exhaust gas outlet pipe and the differential pressure across the diesel particulate filter when the diesel particulate filter is empty at the beginning of the installation of the diesel particulate filter increases beyond a critical threshold, an indication is provided to a user that the diesel particulate filter is required to be replaced. Once the differential pressure 98 caused due to the soot accumulation in the diesel particulate filter is determined, the level of soot 99 accumulated in the diesel particulate filter can be effectively estimated.
[0010] It must be understood that the embodiments explained above are only illustrative and do not limit the scope of the disclosure. Many modifications in the embodiments with regard to dimensions of various components are envisaged and form a part of this invention. The scope of the invention is only limited by the scope of the claims.

1. A method to correct a differential pressure across a new diesel particulate filter, said method comprising:
sensing a differential pressure of exhaust gas between an exhaust gas inlet pipe and an exhaust gas outlet pipe that are each secured to a diesel particulate filter, by means of a differential pressure sensor at a predetermined time interval; comparing the differential pressure of exhaust gas that exists between the fuel inlet pipe and the fuel outlet pipe with a predetermined differential pressure of exhaust gas that is stored within a memory unit; and
offsetting the differential pressure of exhaust gas that exists between the fuel inlet pipe and the fuel outlet pipe to a zero value if the differential pressure of exhaust gas that exists between the fuel inlet pipe and the fuel outlet pipe is one of greater or lesser than the predetermined differential pressure of exhaust gas that is stored within the memory unit.