FIELD OF THE INVENTION

[001]

The present invention generally relates to a method for configuring engine of a generator, and more particularly, but not exclusively, to the method for configuring the engine to meet the requirement of CPCB-II emission standard.

BACKGROUND OF THE INVENTION

[002]
Generator sets are a major source of noise and air pollution, which causes adverse health effects and also create nuisance. The rapid industrialization and growth in urban population has led to higher energy requirement. To meet the shortage in power supply, more and more generator sets are being installed by the industries as well as individuals. Diesel Internal Combustion (IC) Engines are primarily being used for power generation in the generator sets due to its higher thermal efficiency and its superior fuel consumption compared to Gasoline IC Engines. Hence, it is necessary to design and manufacture a diesel engine with less emission of smoke and less noise. The smoke emission is controlled by various emission control techniques such as tighter timing control for fuel ignition time and in-cylinder Exhaust Gas Recirculation (EGR).

[003]
In all the countries, the government has set up a committee or organization to control the air pollution and noise pollution caused by many factors such as generator sets, vehicles etc. The origination or committee designs a various emission standards for various factors of pollution. In order to meet the emission regulations of the government origination or committee, there are several techniques and processes are evolved. Typically, the engine is configured by adding of additional or new electronic items such as sensor, microcontroller to the engine to meeting the requirement of emission norms related to generator sets. Hence, the addition of new electronic items increases the cost as well increases the complexity in assembling of the engine components while manufacturing the engine.

[004]
Accordingly, the Indian government has set up a board called Central Pollution Control Board (CPCB) to set up the emission standard and norm to control the air and noise pollution in India. Recently, CPCB has released the CPCB-II norms for the diesel engines used in the generator sets. A CPCB-II norm is regarded as a specific and stringent emission legislation that regulates emissions in diesel generator engines in India. There is no method and system disclosed to convert/modify the typical engine system which is operating to meet the requirement of CPCB-I emission norms for accommodating the CPCB-II norm. Accordingly there is a need in the art to provide a solution to one or more of above said problems. The present invention solves one or more of these problems in a unique and economical manner.

SUMMARY OF THE INVENTION

[005]
An object of the present invention is to develop an engine configuration with 2-Valve to meet CPCB-II emission norms with conventional rotary mechanical fuel injection system, valve closed orifice nozzle configuration and in-cylinder EGR applied to a turbo-charged diesel IC engine

[006]
Another object of the present invention is to inject fuel from a low pressure system into the combustion chamber of the engine in such a way that combustion of fuel along with the re circulated gas takes place in combustion chamber to reduce Nitric Oxides and particulate matter.

[007]
Another object of the present invention is to develop a valve closed orifice nozzle configuration to assist in the emission reduction. The CPCB-II emission norms derives that the smoke released from the Genset diesel engine includes an Oxides of Nitrogen and Hydrocarbon in the range of 0-4 g/kW-hr, a carbon mono oxide in the range of 0-3.5 g/kW-hr and particulate matter in the range of 0-0.2 g/kW-hr.

[008]
According to one aspect of the present invention which achieves the objectives relates to developing a 2-valve engine capable of meeting CPCB-II norms with a conventional rotary mechanical fuel injection system which pumps the fuel to the combustion chamber through the valve closed/covered orifice nozzle configuration calibrated in tandem to reduce the nitric oxide emissions and particulate matter emissions within the combustion chamber with the help of in-cylinder EGR which is directed through the 2-valve air porting configuration. The present invention discloses a method and optimal technique with reduced cost and up gradation of the engine from CPCB I to CPCB II in minimum time with minimum design changes.

[009]
According to another aspect of the present invention which achieves the objectives relates to pumping the fuel into the combustion chamber of the engine with aid of low pressure injection system and by guiding the exhaust gas to the combustion chamber of the engine such that the combustion of pumped fuel along with the exhaust gas takes place in the combustion chamber of the engine.

[0010]
New invention includes an internal combustion engine having an intake and exhaust manifold. An intake air conduit extends from compressor of turbocharger to intake manifold. An exhaust conduit extends from exhaust manifold to turbine of turbocharger. This air is then introduced in engine cylinder for combustion where it is mixed with the in-cylinder EGR directed through valve porting by valve overlap provided in the camshaft which inducts hot exhaust air from exhaust valve into the intake valve which provides the necessary EGR for emission reduction.

[0011]
In one aspect of the invention, a method for configuring an engine is provided. The method includes (i) configuring a fuel injection pump to start injecting the fuel at a first range of crack angle degree of a cylinder, wherein the first range of crack angle degree is determined based on a power rating of a generator and a load acting on the engine, (ii) configuring a characteristics of a Valve Covered Orifice (VCO) nozzle assembly to inject the fuel into a combustion chamber based on the power rating of the generator and a piston bowl geometry of the engine, wherein the characteristics comprises a through flow, a number of holes and a spray cone angle, and (iii) configuring an exhaust cam lobe and an intake cam lobe to increase a duration of overlapping of a inlet valve and an outlet valve provided in the combustion chamber of the engine.

BRIEF DISCRIPTION OF THE ACCOMPANYING DRAWINGS

[0012]
The advantages and features of the invention will become more clearly apparent from the following description which refers to the accompanying drawings given as non-restrictive examples only and in which:

[0013]
Figures 1A through IE illustrate a pictorial representation of inputs required to design the LLA arrangement for 160 kVA generator to meet the requirement of CPCB-II emission standards in accordance to the preferred embodiment herein;

[0014]
Figures 2A and 2B illustrates a LLA setting points characteristics with respect to an advanced crank angle and a fuel delivery for four cylinder engine and six cylinder engine respectively in accordance to the preferred embodiment herein.;

[0015]

Figure 3 illustrates a schematic diagram of a valve covered/closed orifice nozzle configuration used in the fuel injection pump of the IC engine in accordance to the preferred embodiment herein;
[0016]

Figure 4 illustrates a valve timing diagram for the in-cylinder exhaust gas recirculation arrangement in accordance to the preferred embodiment herein; and
[0017]

Figure 5 illustrate an intake cam lobe and an exhaust cab lobe used for achieving in-cylinder EGR in accordance to the preferred embodiment herein.

DETAILED DISCRIPTION OF THE INVENTION

[0018]

The present invention will be described herein below with reference to the accompanying drawings. A method for configuring an engine is described.

[0019]

The following description is of exemplary embodiment of the invention only, and is not limit the scope, applicability or configuration of the invention. Rather, the following description is intended to provide a convenient illustration for implementing various embodiments of the invention. As will become apparent, various changes may be made in the function and arrangement of the structural/operational features described in these embodiments without departing from the scope of the invention as set forth herein. It should be appreciated that the description herein may be adapted to be employed with alternatively configured devices having different shaped, components, and the like and still fall within the scope of the present invention. Thus the detailed description herein is presented for purposes of illustration only and not of limitation.

[0020]

The present embodiment provides a method for configuring the engine, and more particularly, the embodiment provides the method for configuring a diesel engine in the generator sets to meet the requirement of CPCB-II emission norms. The engine is referred herein and exemplified as the diesel engine in the figures. However, the engine may comprise any engine capable of operating similar to diesel engine.

[0021]

In general, the diesel Internal Combustion (IC) Engine is used in generators. The typical diesel IC engine configured to meet the CPCB-II emission norm by the following method. The CPCB-II emission norms derives that the smoke released from the generator diesel engine includes an Oxides of Nitrogen and Hydrocarbon in the range of 0-4.7 g/kW-hr, a carbon mono oxide in the range of 0-3.5 g/kW-hr and particulate matter in the range of 0-0.3 g/kW-hr. The IC engine operation is mainly governed by two parameters (i.e.) air Supply and fuel supply. The air supply to the engine is provided from the turbo charger input through the in-cylinder exhaust gas re- circulation via the two valve configuration. The in-cylinder exhaust gas recirculation replaces around 8-10% of fresh air with exhaust gas which reduces the maximum combustion temperature, thereby reducing NOx emissions. The air fuel ratio of around 20-25 is maintained by the proper selection of turbocharger for this application. The fuel supply is provided by the rotary fuel injection pump through the valve closed orifice nozzle configuration developed for the engine's combustion bowl. These two systems work in tandem to produce the desired performance and emission results.

[0022]

To minimize exhaust emissions and smoke, the tighter timing control for fuel injection is required in the rotary fuel injection pump. The tighter timing control is accomplished with the LLA (Light Load Advance) arrangement which is designed to optimize the duration of injection under different load conditions. The rotary fuel injection pump is designed to advance or retards the fuel injection based on the predefined LLA setting points to meet the desired emission standards. The predefined LLA setting points are optimized to attain the desired CPCB-II emission standards. The LLA arrangement is designed to control the injection time based on different load conditions and the crank angle position of the piston for different generator ratings. Below is Table I which shows injection duration in terms of crank angle for different load. The table should in no way be construed as limiting.

TABLE I
[0023]

The critical input required to design the LLA arrangement are include the start of injection, end of injection and duration of injection. Figures 1A through IE illustrate a pictorial representation of inputs required to design the LLA arrangement for 160 kVA generator to meet the requirement of CPCB-II emission standards in accordance to the preferred embodiment herein. This input determines the point from which the fuel injection pump should start pumping fuel into the engine based on the position of the piston with respect to TDC (Top Dead Center) of the first cylinder. This value is inclusive of the Line delay (The time taken for the fuel to reach the injector from the fuel injection pump through the high pressure injector pipes) of the injector pipes. This also indicated the time duration for completion of the injection process to have the emissions under control. The inputs are mainly SOI (Start of Injection), EOI (End of Injection) and DOI (Duration of Injection). Figures 1A-1E depicts the terminology of the input in pictorial representation. The combustion pressure is used as a secondary reference to check the SOI values as the SOI values coincides with the peak combustion pressure value.

[0024]

Figures 2A-2B illustrates a LLA setting points characteristics with respect to an advanced crank angle and a fuel delivery for four cylinder engine and six cylinder engine respectively in accordance to the preferred embodiment herein. From the figures 1 A-IB, there is no LLA setting point has been set for the 100 percent load point and 75 percent load point. Hence, fuel injection pump is configured to inject the fuel with no LLA action. However the duration of injection is optimized in the range of 25.5° to 27.5° crank angle degrees for 100 percent load point and 23° to 24° crank angle degrees for different generator ratings (as listed in the table I) to meet the desired CPCB-II emission standards. At 50 percent load point, the LLA action is taken place and this is the setting point determination of the pre-load of the LLA Piston. This is a critical setting point for LLA behavior. Hence, the fuel injection pump is configured to perform LLA action i.e. the LLA piston is activated at advance crank angle degrees as shown in figures 1A-1B for the different generator ratings. The duration of injection is optimized in the range of 18° to 22° crank angle degrees for 50 percent load point for different generator ratings (as listed in the table I). The LLA setting point at 25 percent load point used to determine the spring rate used in the LLA assembly of the rotary fuel injection pump. The LLA setting point at 10 percent load point is determines a maximum advance of LLA. This is used to eliminate the white smoke during starting and during running of the engine at low loads.

[0025]

Figure 3 illustrates a schematic diagram of a valve covered/closed orifice nozzle configuration used in the fuel injection pump of the IC engine in accordance to the preferred embodiment herein. To reduce the emission, the fuel injection pump is configured to inject the fuel using a valve closed orifice nozzle configuration. VCO (Valve Closed/Covered Orifice) nozzles are used for fuel direct injection in Diesel Engines. In VCO nozzles, the holes lead directly to the needle seat area and are therefore shut by the needle itself. Because of this feature, the fuel injection timing and quantities are very accurate but fuel distribution to the different holes is very sensitive to needle/nozzle concentricity during needle lift. To reduce the emission and to meet the CPCB-II emission norms, 7-hole nozzle configuration with a hydraulic through flow of 1800 cc/min and co-efficient of discharge of 0.85 is used. To reduce the emission and to meet the CPCB-II emission norms in 62.5 kVA generator rating, the through flow is configured to 1400 cc/min and the number of holes is configured to 7. The above said nozzle configuration was designed and selected exclusively to suit the requirements to meet performance and emission requirements.

[0026]

The internal combustion engine having an intake and an exhaust manifold. An intake air conduit extends from compressor of turbocharger to the intake manifold. An exhaust conduit extends from the exhaust manifold to the turbine of turbocharger. The in-cylinder EGR is attributed by the use of the valve overlapped camshaft. The valve overlapped camshaft directs the hot exhaust gas from the exhaust valve with the help of exhaust valve overlap during the scavenging process to the combustion chamber through the intake valve overlap. The hot air that enters into the combustion chamber through the intake valve due to valve overlap helps in the reducing the peak combustion temperature and also reduces the amount of fresh air available for combustion. This helps in reducing NOx emissions which in turn aids in achieving the emission requirements of CPCB - II norms. The valve overlap period typically occurs between the opening of the inlet valve and the closing of the exhaust valve(s), the exhaust valve closing after the inlet valve has opened such that both valves are open during the overlap period. Figure 4 illustrates a valve timing diagram for the in-cylinder exhaust gas recirculation arrangement in accordance to the preferred embodiment herein. The valve overlap of the intake valve and the exhaust valve is achieved through valve timing optimization such that it secondary opening of exhaust valve for a duration of 88 deg of crank angles during intake stroke and secondary opening of intake valve for a duration of 64 deg of crank angles during exhaust stroke.

[0027]

During secondary intake valve opening exhaust gases are trapped in the intake manifold which are latter sucked into the cylinder in suction stroke and during the secondary exhaust valve opening, exhaust gases are drawn into the cylinder from the exhaust port. Certain amount of EGR is obtained from the former while the remaining EGR is obtained sequentially during the latter process. The latter also helps in scavenging process.

[0028]

Figure 5 illustrate an intake cam lobe and an exhaust cab lobe used for achieving in-cylinder EGR in accordance to the preferred embodiment herein. The valve overlapped camshaft includes two cam lobes such as an intake cam lobe and an exhaust cam lobe. The intake cam lobe and exhaust cam lobe are positioned above the intake valve and the exhaust valve to control open or close function of the respective valves. The intake cam lobe and exhaust cam lobe are designed to provide more valve overlap timings to direct the hot exhaust gas to inside the combustion chamber. The primary lift is provided for both Intake and Exhaust valve are provided at 0 deg with respect to rotating plane. The secondary lift for the intake valve is started at 218 deg till 234 deg with respect to rotating plane. Similarly the secondary lift for the exhaust valve is started at 119 deg till 147 deg with respect to rotating plane. The maximum lift during the secondary intake and exhaust valve opening occurs at 234 deg and 147 deg respectively.

[0029]

The present embodiment facilitates to provide the diesel engine which is configured to meet the requirement of CPCB-II emission norms. The air supply and fuel supply of the engine is optimized to meet the requirement of CPCB-II emission norms. The air supply is optimized through in-cylinder EGR using overlapped camshaft arrangement. The design characteristics of the intake cam lobe and the exhaust cam lobe are optimized to attain the desired emission norms. The fuel supply for the diesel engine is optimized by configuring the conventional rotary fuel injection pump with LLA arrangement and VCO nozzle assembly. The LLA arrangement is used to control the start of injection, duration of injection and end of injection with respect to crank angle degree of the piston. The VCO nozzle assembly is used to inject the fuel into the combustion chamber to attain the desired emission norms i.e. CPCB-II emission norms.

[0030]

Several exemplary embodiments have thus been described. Modifications and alterations may occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiments be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

We claim:

1. A method for configuring an engine comprising the steps of:
configuring a fuel injection pump to inject a fuel at a first range of crack angle degree of a cylinder, wherein said first range of crack angle degree is determined based on a power rating of a generator and a load acting on said engine; configuring a characteristics of a Valve Covered Orifice (VCO) nozzle assembly based on said power rating of said generator and a piston bowl geometry of said engine, to inject said fuel into a combustion chamber, wherein said characteristics comprises a through flow, a number of holes and a spray cone angle; and configuring an exhaust cam lobe and an intake cam lobe to increase a duration of overlapping of a inlet valve and an outlet valve provided in a camshaft of said engine.

2. The method as claimed in claim 1, wherein said first range of crack angle degree comprises (i) 25.5° to 27.5 ° when said load is 100 percent, (ii) 23° to 24 ° when said load is 75 percent, (iii) 18° to 22 ° when said load is 50 percent, (iii) 14° to 16.5 ° when said load is 25 percent and (iv) 12° to 16 ° when said load is 10 percent.

3. The method as claimed in claim 1, wherein said through flow is configured to 1800 cc/min and said number of holes is configured to 7.

4. The method as claimed in claim 1, wherein said through flow is configured to 1400 cc/min and said number of holes is configured to 7 when said generator rating is 62.5 kVA.

5. The method as claimed in claim 1, wherein said outlet valve of said combustion chamber configured to direct exhaust gas to said inlet valve during said overlapping.

6. The method as claimed in claim 1, wherein said spray cone angle is configured to 146 degree to spray said fuel completely within said combustion chamber.

7. The method as claimed in claim 1, wherein said engine reduces the NOx and particulate matter emissions.

8. The method as claimed in claim 7, wherein said engine emission comprises Oxides of Nitrogen and Hydrocarbon in the range of 0-4.7 g/kW-hr, a carbon mono oxide in the range of 3.5 g/kW-hr and particulate matter in the range of 0-0.3 g/kW-hr.

9. An engine comprising: an fuel injection pump which is configured to inject a fuel with respect to first range of crank angle degrees, wherein said first range of crank angle degrees is determined based on a power rating of a generator and a load acting on said engine; a Valve Covered Orifice (VCO) nozzle assembly configured to inject said fuel into a combustion chamber; and a camshaft comprising an intake cam lobe and an exhaust cam lobe which are configured to increase a duration of overlapping of an intake valve and an exhaust valve of said combustion chamber to allow said exhaust gas to said combustion chamber through said outlet port.