FORM 2
THE PATENT ACT, 1970,
(39 OF 1970)
&
THE PATENTS RULE, 2003
COMPLETE SPECIFICATION
(SEE SECTION 10; RULE 13)
"VEHICLE SPEED PROFILE ADAPTED SOOT BURNING METHOD TO ENHANCE
REGENERATION EFFICIENCY"
MAHINDRA & MAHINDRA LIMITED
AN INDIAN COMPANY,
R&D CENTER, AUTOMOTIVE SECTOR,
89, M.I.D.C., SATPUR,
NASHIK-422 007,
MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES AND ASCERTAINS THE NATURE OF THIS INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

TECHNICAL FIELD:-
The present invention relates to the usage of the average vehicle speed for the evaluation of the soot burning duration to achieve optimum regeneration efficiency. The average vehicle speed over the previous soot loading cycle is taken into consideration to identify the pattern of soot formation. Based on this average vehicle speed information, regeneration duration can be increased or decreased based on the requirement.
BACKGROUND OF THE INVENTION:-
Diesel engines for Euro-5 application will need Diesel particulate Filters for reduction of particulate matter. Diesel particulate filters of the wall flow type, have about 95 % filtration efficiency. With the increase in the soot mass in the DPF, the DPF has to be regenerated to continue the soot accumulation. Active Regeneration of DPF by late post injection needs to be optimized for correct duration considering balance between regeneration efficiency and oil dilution. Soot burning conventionally is influenced by oxygen content in the exhaust during regeneration and the temperatures that can be achieved to regenerate. 'Regeneration Efficiency' is the percentage representation of the ratio of the actual amount of soot burnt during regeneration to the actual soot at the start of the regeneration. 'Oil Dilution' is the phenomenon by which the engine oil is diluted with diesel resulting in the deteriorated engine oil viscosity properties. The phenomenon is dominated when retarded injection pattern is used.
US. Patent no. US 7992381 B2 discusses the methodology of two stage temperature and oxygen requirement for better regeneration efficiencies.
US. Patent no. US 7937935 B2 discusses the identification of the consituents of the Particulate matter accumulated in the DPF, thereby adapting the maximum threshold for the regeneration trigger for preventing the damage of the DPF.

A well known problem is to provide optimum regeneration duration to compromise between regeneration efficiency and oil dilution. A too high regeneration duration will cause Oi! dilution and a too low regeneration duration will result in poor regeneration efficiency.
It is a principal objective of the present invention to implement a third factor other than Oxygen concentration and exhaust temperature to influence the regeneration duration and hence the regeneration efficiency. This factor would be the average vehicle speed over the soot accumulation cycle before regeneration.
SUMMARY OF THE INVENTION:-
Usage of Average vehicle speed for the evaluation of the regeneration duration will result in optimum regeneration duration. The vehicle average speed will help to identify the city, extra urban and highway driving cycle to adjust accordingly for the regeneration duration.
The duration of regeneration based on the average vehicle speed is controlled via control algorithm programmed into the Engine management control unit. The additional control algorithm for the regeneration duration evaluation is also a part of the invention.
Diesel Engines with Particulate filter as after-treatment device for Particulate matter reduction needs effective regeneration control for optimum performance. Optimum regeneration duration is considered to yield best results for regeneration efficiency and also for engine oil dilution. The method provides a simplified approach to evaluate the optimum soot burning duration by using the average vehicle speed as the input for soot burning.
BRIEF DESCRIPTION OF THE FIGURES:-
Figure 1. Indicates the existing model for the regeneration duration evaluation
Figure 2. Indicates the additional changes based on average vehicle speed used for regeneration duration evaluation

Figure3. Indicates the soot burning model determined based on the soot mass, lambda in the exhaust and the vehicle speed based correction factor for soot mass burning duration determination
DESCRIPTION OF THE PREFERRED EMBOPIMENT:-
Active Regeneration in Diesel particulate filters is carried out with late post injection. The duration of soot burning is dependent on oxygen concentration and the exhaust temperature during regeneration.
For regeneration to be efficient, the regeneration duration plays a vital role. A lower regeneration duration will result in reduced regeneration efficiency and reduced subsequent regeneration intervals and frequent regenerations. A higher regeneration duration will result in better regeneration efficiencies but results in more engine oil dilution problems.
Soot accumulation profile gives a feedback about the HC constituents of the soot in the DPF. An evaluation with different regeneration patterns with highway and city driving soot accumulation resulted in faster and efficient soot burning tendencies with highway driving profile. During city profile evaluation the regeneration efficiency for the same duration was on the slower side. Providing regeneration temperatures in city cycle profile for long durations is a challenge and also involves in substantially higher Post injection quantities creating higher risk of oil dilution with very high regeneration duration.
A correction factor provided in the control algorithm based on the cycle used for soot accumulation (city / highway / Extra urban) is used for calculating the time needed to regenerate the soot in the DPF.
Figure 1. describing the conventional soot burning algorithm contains only Oxygen content and exhaust temperature as the inputs. This algorithm does not consider any additional influence in the soot burning duration due to the vehicle speed profile.

Figure 2. describes the additional of correcting the existing model with vehicle speed dependent factor.
Soot burning model in the calibration logic involves the calibration of the duration of the regeneration. Conventional soot burning model involves the usage of exhaust temperature before DPF and the oxygen content in the exhaust. With the usage of the vehicle speed as a correction factor for the soot burning rate, the regeneration efficiency and the regeneration duration can be optimised for optimum results.
Regeneration input based based on vehicle speed involves in the identfication of the cycle where the soot loading pattern has occurred. On comparing the city cycle with the highway cycle, as the exhaust temperatures in the highway cycle are higher and substantial occurence of passive regeneration because of Nox is possible the regeneration duration can be less than the regeneration duration in City cycle. Also because of the better temperature controller stability in highway cycle the regeneration efficiency is better thatn in city cycle.
Ideally for the soot burning to happen from fully loaded DPF to empty DPF, the regeneration duration is lesser in highway cycle than in the city driving pattern for the above mentioned reasons.
Without the utilization of this factor based on the vehicle speed, the regeneration duration will have to be kept to a constant between highway and city cycle, leading to oil dilution and poor regeneration efficiency.
The vehicle speed is tapped from the vehicle speed sensor available in the base patform for the engine ECU. The vehicle speed is used to determine the average vehicle speed in the previous soot accumulation cycle.
The determination of the vehicle speed average is started from theime one regeneration is complete. The vehicle average speed at the beginning of regeneation is used as input for determining the correction factor for the regeneration duration determination as in the figure3.

Ideally the current strategy as per the invention is to use a correction factor to increase the soot burning duration in city driving profile and to reduce the soot burning duration in the highway cycle. The extra urban / mixed cycle will have the combined benefits of both the regeneration duration strategies.
The present Invention should not be limited to the disclosed embodiments, but may be implemented in many other ways, without departing from the spirit of the invention.

WE CLAIM:-
1. Vehicle speed profile adapted soot burning method to enhance regeneration efficiency comprises the steps of calibration of the duration of the regeneration; taking the inputs of the vehicle speed as a correction factor for the soot burning rate; and then optimizes the regeneration efficiency and the regeneration duration for the optimum results; wherein the regeneration input based on the vehicle speed involves in the identfication of the cycle where the soot loading pattern has occurred.
2. Vehicle speed profile adapted soot burning method to enhance regeneration efficiency as claimed in claim 1, wherein it comapres the city cycle with the highway cycle as the exhaust temperatures in the highway cycle are higher and substantial occurence of passive regeneration happens because of Nox and the regeneration duration is less than the regeneration duration in City cycle.
3. Vehicle speed profile adapted soot burning method to enhance regeneration efficiency as claimed in claim 1, wherein the vehicle speed is tapped from the vehicle speed sensor available in the base platform for the engine ECU and the vehicle speed is used to determine the average vehicle speed in the previous soot accumulation cycle; and the vehicle average speed at the beginning of regeneation is used as input for determining the correction factor for the regeneration duration determination.