FORM - 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE
Specification
(See section 10 and rule 13)
DIESEL ENGINE WITH IMPROVED EMISSION
CHARACTERISTICS

KIRLOSKAR OIL ENGINES LTD
an Indian Company of Laxmanrao Kirloskar Road, Khadki, Pune 4 Maharashtra, India.

THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE
PERFORMED.

Field of invention:
This invention relates to a diesel engine with improved emission characteristics.
Background of the invention:
In a diesel engine that works on a 4-stroke cycle, air is drawn inside the cylinder due to the motion of the piston, from one end to the other, in the cylinder. These ends are termed as 'top dead center (TDC)' and 'bottom dead center (BDC)". Air comes in through a passage in the cylinder head, generally called as "inlet port" that has a valve at one of its opening at the cylinder end. This valve is opened at a particular moment during the cycle and air is admitted into the cylinder head, this is called the 'suction stroke' out of the 4-stroke cycle. Further this air is compressed in the next stroke called as 'compression stroke' due to the motion of the piston from BDC to TDC. The air gets compressed upto such an extent that temperature of air rises resulting in spontaneous igniting of the fine droplets of diesel sprayed at the end of the compression stroke. These fine droplets are mixed intimately with the air in the cylinder. Ignition cause violent explosion, which expands the air resulting in motion of the piston from TDC to BDC, which is called the 'expansion/power stroke' The burnt gases are then expelled out of the cylinder during the next stroke, called 'exhaust stroke' during which the piston from BDC to TDC. For expelling the burnt gases, there is another passage in the cylinder head called as the 'exhaust port', which also has a valve similar to the inlet valve and opens at a particular moment during the above cycle. The reciprocating motion of the piston during repetitive and sequential suction, compression, expansion and
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exhaust strokes (called as 4-stroke cycle) causes rotation of a crankshaft due to its connection to the piston by a 'connecting rod'.
In diesel engines the inlet and exhaust ports act as pathway for admitting fresh air and removing exhaust gases respectively. The design of these ports has a large effect on the economy and performance of the engine. Two dimensionless numbers namely 'swirl number and 'flow coefficient' play a dominant role in engine design, thermodynamic performance and exhaust emissions. Swirl number relates to the rotation of the fluid in the cylinder and the flow coefficient is a measure of the pressure loss introduced by the port/valve combination.
Swirl number is defined as the ratio of the anemometer speed measured by the stationary flow test and fictitious engine speeds obtained by equating the mean axial flow velocity to mean piston speed. The swirl number represents airflow patterns. Swirl number is optimized based on the engine size. The swirl improves air and fuel mixing which results in efficient combustion in turn resulting into reduction in exhaust emissions like smoke and particulate matter.
Flow co-efficient is the ratio of actual flow rate at a certain pressure drop through a known cross-section to the theoretical mass flow rate at equal pressure drop through a reference cross-section. Flow coefficient improves breathing of the engine and hence improves air to fuel ratio, which reduces emissions like NOx, HC and CO.
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Emission of various types of gases is an important consideration for the purpose of engine design. It is a mandatory requirement that engines should meet the national and international emission requirements. Hence it is necessary that engine components be designed in a manner such that the emission is below the prescribed limit.
Prior Art:
In the Diesel engines known in the prior art, the inlet port and the exhaust port are tangentially provided in the cylinder head, both the ports have circular openings and both the ports are located on the same side of the piston head. Such construction of the cylinder head leads to incomplete combustion of the fuel (Diesel) in the engine cylinder, resulting into higher pollutants such as carbon monoxide (CO), Oxides of Nitrogen (NOx), HC, PM, smoke in the exhaust emissions from the engine. Exhaust emissions from the engine creates air pollution causing health hazards, and therefore, exhaust emissions from the engines are required to be maintained within the prescribed limits, beyond which it is not permissible.
Referring to figures 1, 2 and 3 of the accompanying drawings which respectively illustrates plan view, right hand side view and sectional view as seen in the direction of line A-A' in figure 1, of a cylinder head in accordance with the prior art. The cylinder head (20) of a diesel engine comprises an air inlet port (22) and exhaust port (24) provide side by side on the same side of the cylinder head (20). The inlet port (22) and the outlet port (24) are tangential ports with a circular cross section. An injection nozzle (26) and a cooling passage (28) are also provided within the cylinder head (20). An inlet valve (30) is provided at the cylinder end of the inlet port
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and an exhaust valve (32) is provided at the cylinder end of the exhaust port. The air inlet port (22) and the exhaust port (24) are provided side by side, thus the air entering in the cylinder is not isolated from the hot exhaust gases in the exhaust port (26), hence air entering the inlet port (22) gets heated before entering the cylinder, which in turn affects the engine efficiency. Further, the inlet port (22) being tangential, swirl depends mainly on the interaction of air flowing into the cylinder and the walls of the cylinder. This results in incomplete combustion of fuel causing high level of pollutants in the exhaust gases. Such high levels of pollutant emissions are not permissible in accordance with the emission norms.
This invention seeks to overcome the limitations of the prior art.
An object of this invention is to reduce the emission of pollutants from the exhaust emission of an engine.
Another object of this invention is to provide a cylinder head, which achieves an optimum value of swirl number and flow coefficient.
Another object of this invention is to provide an improved system for facilitating complete combustion of fuel.
An object of this invention is to isolate the exhaust gases from the fresh air entering the inlet port of the cylinder head of an engine.
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Summary of the invention:
In accordance with this invention there is provided a cylinder head
comprising:
(i) an air inlet port defined by a helically shaped passage having an
inlet opening and an outlet opening, said passage defining an inlet end
portion having a rectangular cross section and an outlet end portion
having a circular cross section;
(ii) an exhaust port defined by a passage having an inlet opening
and an outlet opening for removal of exhaust gases;
(iii) a fuel injection nozzle for supply of fuel to said cylinder; and
(iv) at least one cooling passage to cool said air inlet port and
exhaust port.
Typically, the rectangular cross section portion extends upto 60 to 70% of
the total length of the helical passage.
Typically, the inlet opening of the inlet port and the outlet opening of the
exhaust port are on opposite side of the cylinder head.
Typically, the rectangular section of the helical passage is smoothly
converted to a circular cross section of the helical passage.
Brief description of the accompanying drawings:
The invention will be described in detail with reference to a preferred
embodiment. Reference to this embodiment does not limit the scope of the
invention.
In the accompanying drawings:
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Figure 1, 2 and 3 respectively illustrates plan view, right hand side view and sectional view as seen in the direction of line A-A in figure 1, of a cylinder head in accordance with the prior art;
Figure 4, 5, 6 and 7 respectively illustrate plan view, right hand side view, left hand side view and sectional view in the direction of the line A-A as seen in figure 4, of a cylinder head in accordance with this invention; Figure 8 illustrates a perspective view of the engine cylinder with piston and connecting rod assembly having cylinder head according to this invention; Figure 9 illustrates a tabulated emission report of a water-cooled engine for an engine incorporating a cylinder head known in the prior art; Figure 10 illustrates a tabulated emission report of a water-cooled engine for an engine incorporating a cylinder head in accordance with this invention; Figure 11 illustrates a tabulated emission report of an air-cooled engine for an engine incorporating a cylinder head known in the prior art; and Figure 12 illustrates a tabulated emission report of an air-cooled engine for an engine incorporating a cylinder head in accordance with this invention.
Detailed description of the invention:
The invention will now be explained with reference to Figures 4 to 12 of the accompanying drawings.
Figure 4, 5, 6 and 7 respectively illustrate plan view, right hand side view, left hand side view and sectional view in the direction of the line B-B' as seen in figure 4, of a cylinder head (34) and Figure 8 illustrates a perspective view of the engine cylinder with piston and connecting rod assembly having cylinder head according to this invention. The cylinder head (34) is provided with exhaust port (36) and air inlet port (38) on the opposite sides of the
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cylinder head (30) and are preferably diametrically opposite to each other thereby facilitating isolation of hot exhaust gases in the exhaust port (36) from the air entering the inlet port (38) which will remain cool, resulting in better performance of the engine. The cylinder head (34) is also provided with injection nozzle (40) and cooling passage (42).
The total length of the inlet port (38) is the range of 120mm to 150mm. The opening of the inlet port (38) at the air entry end has a rectangular cross section, this rectangular cross section is maintained for upto 60% to 70% of the total length of the inlet port (38). For an engine with bore x stroke value of 95 x 110mm the inlet end portion having a rectangular cross section has width x height dimensions of 31 x 43mm. For an engine with bore x stroke value of 102 x 116mm the inlet end portion having a rectangular cross section has width x height dimensions of 32.5 x 64.5mm. For an engine with bore x stroke value of 114.3 x 116mm the inlet end portion having a rectangular cross section has width x height dimensions of 32.5 x 64.5mm. The remaining 30 to 40% of the port length is smoothly converted to have a circular cross section. The opening of the inlet port (38) at the cylinder end has a circular cross section. The change in the cross section through the length of the port facilitates in making the inlet port (38) helical within the space available in the cylinder head (34). The helical inlet port (38) is such that the airflow, upstream the valve is brought in rotation and therefore exits the inlet valve (44) with an angular velocity component around the valve axis. This, in turn results in a higher air rotation in the cylinder which helps in achieving complete combustion of the fuel and giving acceptable emission norms. The helical air inlet port (34) provided in the cylinder head (30) achieves a suitable value of flow coefficient and swirl number such that
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exhaust emission contain lower pollutant content thus satisfying emission norms.
The exhaust port (32) may also be provided with rectangular cross section at the exit end of the exhaust gases, which is smoothly converted into circular cross section at the piston end of the exhaust gases. At the exit end of the exhaust gases an exhaust valve (46) is provided which opens at the start of the exhaust stroke thus helping in removing the exhaust gases from the engine cylinder.
For the purpose of testing a test rig was set up to determine the smoke and exhaust emissions for different types of water cooled and air cooled engines as known in the prior and in accordance with this invention. Similar engines were selected as known in the prior art and in accordance with this invention with respect to bore x stroke values. Three representative engines of each type having an inlet port of length 145mm were selected in the trials, all engines were set up at a uniform speed of 1500 rpm, the following parameter namely specific fuel consumption (SFC), exhaust temperature, lub oil pressure and temperature, smoke and exhaust emissions were noted for all the engines except that the volume of smoke generated was not checked for engine of the prior art. The results were tabulated and are shown in figures 9 to 12 of the accompanying drawings. The specific fuel consumption for all bore x stroke values was found to be consistently lower in engines in accordance with the present invention as compared to engines known in the prior art.
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The smoke generated in the exhaust emissions measured in BOSCH was significantly lower in engines in accordance with the present invention as compared to engines known in the prior art.
Similarly values of NOx, HC, CO and particulate matter in the exhaust emissions was found to be consistently and significantly lower in engines in accordance with this invention as compared to engines known in the prior art. These test results therefore confirm the adoption of the features of the present invention, which on one hand improves the fuel consumption and also concomitantly improves the quality of the emissions including smoke, HC, CO, NOx and particulate matter.
A diesel engine used for gensets, incorporating a cylinder head in accordance with this invention was tested, the data tabulated below was obtained as a result of the tests. Hie improvements achieved in the emission levels are as below:

Parameter Unit % Improvement (reduction in emission parameter)
Nox gm/kW-hr 50 to 60
CO gm/kW-hr 60 to 63
HC gm/kW-hr 82 to 88
PM gm/kW-hr 76 to 80
Smoke Bosch No. 58 to 60
The reduction in emission parameters obtained are a result of the decrease in swirl number from approximately 3.7 to approximately 2.5/2.7 and increase in the value of flow co-efficient from 0.30 to 0.35/0.36. Value of swirl
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number is directly proportional to the fuel consumption and value of flow coefficient is inversely proportional to the fuel consumption. Hence the specific fuel consumption reduces from 251gms/kW-hr to 230/235 gms/kW-hr, due to the cylinder head used in accordance with this invention.
While considerable emphasis has been placed herein on the various components of the preferred embodiment and the interrelationships between the component parts of the preferred embodiment, it will be appreciated that many alterations can be made and that many modifications can be made in the preferred embodiment without departing from the principles of this invention. These and other changes in the preferred embodiment as well as other embodiments of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.
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We claim;
1. A cylinder head for an engine cylinder, said cylinder head comprising:
(i) an air inlet port defined by a helically shaped passage having an inlet opening and an outlet opening, said passage defining an inlet end portion having a rectangular cross section and an outlet end portion having a circular cross section;
(ii) an exhaust port defined by a passage having an inlet opening and an outlet opening for removal of exhaust gases;
(iii) a fuel injection nozzle for supply of fuel to said cylinder; and
(iv) at least one cooling passage to cool said air inlet port and exhaust port.
2. A cylinder head as claimed in claim 1, wherein said rectangular cross section portion extends upto 60 to 70% of the total length of said helical passage.
3. A cylinder head as claimed in claim 1, wherein said inlet opening of said inlet port and said outlet opening of said exhaust port are on opposite side of said cylinder head.
4. A cylinder head as claimed in claim 1, wherein said rectangular section of said helical passage is smoothly converted to said circular cross section of said helical passage.
5. A cylinder head as claimed in claim 1, as described herein with reference to the accompanying drawings.

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ABSTRACT
A filter assembly for fuel is disclosed. The assembly includes a housing and a filter element located in the housing and held in place by a spring. In the space between the inner wall of the housing and the base of the filter element a compressibly resilient element is located which absorbs hydraulic pulses, the filter assembly is subjected to.
- 6 MAR 2006