FIELD OF INVENTION
The present invention concerns boosting air supply to diesel engines. In particular, the present invention relates to a system for enhancing air supply to a single-cylinder diesel engine having intermittent exhaust gas flow. More particularly, the present invention relates to a system for boosting air supply to a single-cylinder diesel engine by supercharging and turbo-compounding.
BACKGROUND OF THE INVENTION
Power turbine rotates when the exhaust gases pass through the turbine utilizing some of the energy of the exhaust gases. Power turbine is usually coupled to the crankshaft of the engine through suitable drive for the purpose of compounding, i.e. Turbo-Compounding. Conventionally, the turbocharger employs the compressor and turbine mounted on single shaft.
Supercharger is a mechanical device which compresses air from atmosphere to a higher pressure above ambient in order to deliver it to the engine/cylinders.
Supercharger can be driven by belt drive or gear drive or any other drive. For example, belt drive couples the supercharger to receive power from the engine crankshaft. Similarly, power turbine can be driven by any drive. For example, a gear drive delivers the power generated by the power turbine back to the engine crankshaft.
Internal combustion engines involve single cylinder engines or multi-cylinder engines. However, single cylinder engines are always difficult to turbocharge, whether petrol powered single cylinder engines or diesel-powered engine.

In particular, turbocharging of single cylinder diesel engine is difficult due to a phase lag experienced between the Intake and exhaust valve opening duration therein, which is explained below.
On opening the exhaust valve, exhaust gases available at high pressure and temperature rush out through the exhaust port and hits the turbine blades of the turbocharger, which increases the speed of turbocharger and this in turn enables the compressor to compress air to a pressure higher than the ambient pressure. However, this compressed air has no place to go to because the intake valve is closed during the exhaust stroke of the engine. When the intake valve is opened during the operation thereof, the turbine does not receive the exhaust energy because the exhaust valve is already closed. This creates a phase lag between the intake valve opening period and the exhaust valve closing period, during which the turbocharger speed cannot be increased for charging the engine with high pressure air.
PRIOR ART
US2015007560A1, titled: "Turbocharged single cylinder internal combustion engine using an air capacitor" discloses an internal combustion engine system, which includes a single-cylinder engine having an engine volume, the single cylinder engine having an intake manifold for introducing air into the engine and an exhaust manifold for discharge of exhaust gases. A turbocharger communicates with the exhaust manifold to receive exhaust gases to power the turbocharger. The turbocharger includes a compressor section communicating with the intake manifold to pressurize ambient air. An air capacitor is arranged to receive the pressurized ambient air from the turbocharger and to deliver the pressurized air to the engine during an intake stroke.

A reference is also made to an unpublished Indian patent application for an invention by the same inventors as of the present application.
It is titled "A plenum unit for a turbocharged single-cylinder engine" and concerns a turbocharger assembly for a single-cylinder engine (200) includes a plenum unit (100) having an inlet (110), an inlet flange (115), a chamber (105), and a turbocharger (215) mounted on the engine (200). The plenum (105) reduces the fluctuations in the speed of the turbocharger and increases the life and efficiency of the engine (200). A pressure sensor is placed inside the plenum unit (100).
Moreover, as the exhaust energy is available only intermittently (i.e. the exhaust valve of a single-cylinder engine opens only once for about 240° during every two revolutions of the crankshaft, i.e. 720° of crank angle.
Whereas, in multi-cylinder diesel engines has exhaust valves provided for each cylinder and so one of the cylinders will always be in an exhaust stroke, thus providing the energy of exhaust gases to the turbine across the aforesaid 720° crank angle.
Therefore, this intermittently available exhaust gases in single-cylinder engine operation create exhaust pulses, which in turn cause fluctuations in the speed of the turbocharger. These speed fluctuations drastically damage the bearings of turbocharger.
In addition, due to the occurrence of intermittent exhaust pulses, the turbocharger experiences very high thrust forces which also cause serious damages to thrust bearings thereof.

Further, the turbocharger experiences high losses, both at the compressor side and at the turbine side. So, the turbocharger operates not under a steady state condition but operates high fluctuations. This impairs the operations of the compressor and turbine and causes them to function at very low efficiencies due to several losses like windage losses.
Charging air into the engine by other means, for example by employing a mechanically driven supercharger substantially increases the fuel consumption, because this supercharger consumes some power and this power is tapped from the crankshaft itself.
So, the engine power boost is achieved at the cost of higher fuel consumption, which is a serious disadvantage. Accordingly, boosting air charge of the single cylinder diesel engines has always been a difficult task.
Therefore, there is an existing need for enhancing the air-charging of single-cylinder engines, particularly single-cylinder diesel engines, which however does not increase fuel consumption of the engine.
OBJECTS OF THE INVENTION
Some of the objects of the present invention - satisfied by at least one embodiment of the present invention - are as follows:
An object of the present invention is to provide a fuel-efficient system for enhancing air-charging in single-cylinder diesel engines.
Another object of the present invention is to provide a system for enhancing air-charging in single-cylinder diesel engines to increase the engine power.

Still another object of the present invention is to provide a system for increasing power of single-cylinder engines by incorporating the impulse power turbines.
Yet another object of the present invention is to provide a system for enhancing air-charging in single-cylinder diesel engines by decoupling of compressor/supercharger from the turbine of turbocharger.
A further object of the present invention is to provide a system for enhancing air-charging in single-cylinder diesel engines to reduce fuel consumption and thus to improve fuel economy.
Still further object of the present invention is to provide a system for enhancing air-charging in single-cylinder diesel engines to reduce pollution.
These and other objects and advantages of the present invention will become more apparent from the following description, when read with the accompanying figures of drawing, which are however not intended to limit the scope of the present invention in any way.
DESCRIPTION OF THE INVENTION
Compressor/Supercharger is directly coupled to the engine crankshaft by belt drive or gear drive or other suitable means. The turbine is directly coupled to the engine crankshaft via suitable belt drive or gear drive or other suitable means.
Supercharger helps in boosting the intake air, thereby improving the engine power. But supercharger consumes power for delivering boosted air.

The crux of the present invention is in de-coupling the compressor and the turbine of the conventional turbocharger. Since the compressor is de-coupled from the turbine of the turbocharger, the supercharger can be suitably selected un-biased for catering to a wide range of speeds.
This turbo-compounding provide in accordance with the present invention helps in improving the power delivered by the engine. The pulsated or intermittent exhaust flow having high kinetic energy is extracted better using an impulse turbine than a conventional reaction type of turbocharger turbine.
Unlike a conventional turbocharger turbine which has to be matched with the compressor, the present invention facilitates in selecting/designing the turbine according to the engine characteristics and un-biased.
Therefore, the impulse power turbine is most suitably for extracting energy from the pulsated flow of exhaust gases, which is typical for single cylinder engines.
SUMMARY OF INVENTION
In accordance with the present invention, there is provided a system for supercharging and turbo-compounding of single-cylinder diesel engine, the system comprises:
• a diesel engine coupled to a power turbine and a supercharger;
• the power turbine decoupled from the supercharger;
• the supercharger driven by the engine to supply compressed air thereto;

• the power turbine connected downstream the exhaust outlet of the engine for generating additional power from exhaust gases produced therein;
wherein the power turbine and the supercharger are directly coupled to the crankshaft of the engine on either side thereof by means of a power drive.
Typically, the power turbine comprises a direct coupling to the engine via a gear or belt drive.
Typically, the power turbine is configured based on the characteristics of the engine.
Typically, the power turbine is an impulse turbine for better extraction of power from the high kinetic energy contained in pulsated or intermittent exhaust gas flow from the engine.
Typically, the power turbine is un-biased by decoupling thereof from the compressor, the compressor being independent of the impulse turbine for power requirements thereof.
Typically, the supercharger comprises a direct coupling to the engine via a gear or belt drive.
Typically, the supercharger comprises a compressor directly driven by the engine to supply compressed air thereto to boost air supply thereof.
Typically, the supercharger is directly coupled to the crankshaft of the engine via a gear or belt drive.

Typically, an intake plenum is disposed between the supercharger and the intake port of the engine; the intake plenum having an inlet manifold (356) for storing compressed air delivered from the compressor to be supplied to the engine whenever required, on opening of the intake port.
Typically, the power turbine comprises a convergent nozzle and an impeller; the nozzle being disposed between the impeller and the exhaust port of the engine; the nozzle directing the exhaust gases towards the blades of the impeller for rotation thereof.
Typically, the power turbine is selected individually depending on the requirements of the engine to make the system operable at any range of speeds, such as low-speeds as well as at high-speeds.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The present invention will be briefly described in the following with reference to the accompanying drawings.
Figure 1 shows a conventional air-charging layout for a single-cylinder diesel engine.
Figure 2 shows a conventional air-charging layout for a single-cylinder diesel engine with turbocharger coupled to the compressor on the same shaft.
Figure 3 shows an improved system for air-charging of a single-cylinder diesel engine configured with super charging and turbo-compounding therein.

Figure 4 shows an improved air-charging layout of the system of Figure 3.
Figure 5 shows conventional exhaust port layout of the single-cylinder engine system of Figure 4 depicting the exhaust port thereof.
Figure 6 shows an improved air-charging layout of the system of Figure 3 depicting the exhaust power turbine thereof coupled to the single-cylinder diesel engine flywheel through gear drive.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
In the following, the system for boosting air supply to a single-cylinder diesel engine by supercharging and turbo-compounding and configured in accordance with the present invention will be described in more details with reference to the accompanying drawings without limiting the scope and ambit of the present invention.
Figure 1 shows a conventional air-charging layout for a single-cylinder diesel engine 10 having an intake port 12, and exhaust port 14 and a line 16 for conducting exhaust gases from exhaust port 14 to turbine 20 of turbocharger 40. Turbocharger 40 includes a turbine 20 and compressor 30 coupled to each other and mounted on the same shaft 35. Turbine 20 includes an inlet 22 for drawing exhaust gases from exhaust port 14 and an exhaust outlet 24. Compressor 30 includes inlet 32 for ambient or atmospheric air 05 to be compressed and outlet 34 for supplying compressed air 36 to engine 10 for better fuel combustion.
Figure 2 shows a conventional air-charging layout for a single-cylinder diesel engine 110 with power turbine 140 and supercharger/compressor 150. Engine 110 includes an intake port 112 and exhaust port 114. Line 116

supplies exhaust gases from exhaust port 114 to inlet port 122 of turbine 120 and exhaust gases are exhausted from exhaust outlet 124 thereof. Here, supercharger/compressor 150 is decoupled from power turbine 140. Compressor 130 has inlet 132 for ambient or atmospheric air 05 to be compressed and exited from outlet 134 and supplied via line 136 through intake port 112 of engine 110 to achieve better combustion.
Figure 3 shows an improved system 200 for air-charging of a single-cylinder diesel engine 210 configured with an arrangement for supercharging and turbo-compounding therein. Engine 210 includes intake and exhaust ports 212, 214 connected to power turbine 220 via exhaust line 216. Turbine 220 has exhaust inlet 222 and exhaust 224. Decoupled Supercharger/compressor/250 includes a compressor 230 having inlet 232 for drawing atmospheric air 05 for compression and outlet 234 for supplying compressed air for combustion via line 236 to intake port 212 of engine 210. A mechanical coupling 218 couples the engine crankshaft (not shown) to supercharger/compressor 250 for operation thereof. Another mechanical coupling 228 is coupled between the engine crankshaft (not shown) and power turbine 240 which transfers additional power generated by the exhaust gases received in the power turbine 220.
Figure 4 shows a further improved air-charging layout of the system 300, in which the engine 310 receives air compressed through inlet port 312. Compressor/supercharger 350 includes a compressor 330 having inlet 332 to draw air from atmosphere 05 and via a direct discharge outlet 334 feeds compressed air 336 into the intake plenum 355. Intake plenum 355 includes an inlet manifold 356 to store compressed air 336 delivered from compressor 330 and to be supplied to the engine 310 whenever required, i.e. on opening of intake valve 312. A mechanical coupling 318 couples the engine crankshaft (not shown) to the supercharger/compressor 350, 330

receiving power from engine 310 to rotate the compressor shaft (not shown). Another mechanical coupling 328 couples the engine crankshaft (not shown) to power turbine 340. The exhaust gases produced after combustion in engine 310 are exhausted through exhaust port 314 and passed via a convergent nozzle 315 to turbine 340. Exhaust gases 316 hit blades of impeller 320 of the power turbine 340 for rotation thereof.
Figure 5 shows a layout of the conventional exhaust port layout of the single-cylinder engine 100 of Figure 2 depicting the exhaust port 114 thereof.
Figure 6 shows an improved air-charging layout of the system 300 of Figure 4 depicting the power turbine 340 and flywheel 370 of single-cylinder engine 310 coupled via idler gear 380 to gear drive 390 connected to engine crankshaft X.
TECHNICAL ADVANTAGES AND ECONOMIC SIGNIFICANCE
The air-charging system for single-cylinder engine having impulse turbine in turbocharger thereof by supercharging and turbo-compounding and configured in accordance with the present invention offers the following advantages:
• Enables an un-biased supercharger selection irrespective of the turbine/power turbine chosen, unlike the conventional turbocharger.
• Substantially increases fuel-efficiency of single-cylinder engines.
• Most-suitable for optimized turbine selection/design to single-cylinder diesel engine characteristics, optimized power turbine design/selection in order to extract maximum power, unlike

conventional turbocharger in which turbine design influences the compressor design/selection.
• Impulse power turbine facilitates extracting energy recovery from exhaust gases despite pulsated flow thereof.
• Efficient boosting of single cylinder engine (without losing very high exhaust energy).
• Extracting maximum energy of exhaust gas otherwise wasted into the atmosphere, by placement of a power turbine.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments.
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. The exemplary embodiments described in this specification are intended merely to provide an understanding of various manners in which this embodiment may be used and to further enable the skilled person in the relevant art to practice this invention.
Although, the embodiments presented in this disclosure have been described in terms of its preferred embodiments, the skilled person in the art would readily recognize that these embodiments can be applied with modifications possible within the spirit and scope of the present invention as described in this specification.

Accordingly, the skilled person can make innumerable changes, variations, modifications, alterations and/or integrations in terms of materials and method used to configure, manufacture and assemble various constituents, components, subassemblies and assemblies, in terms of their size, shapes, orientations and interrelationships without departing from the scope and spirit of the present invention.
The numerical values given of various physical parameters, dimensions and quantities are only approximate values and it is envisaged that the values higher or lower than the numerical value assigned to the physical parameters, dimensions and quantities fall within the scope of the disclosure unless there is a statement in the specification to the contrary.
Throughout this specification, the word "comprise", or variations such as "comprises" or "comprising", shall be understood to imply including a described element, integer or method step, or group of elements, integers or method steps, however, does not imply excluding any other element, integer or step, or group of elements, integers or method steps.
The use of the expression "a", "at least" or "at least one" shall imply using one or more elements or ingredients or quantities, as used in the embodiment of the disclosure in order to achieve one or more of the intended objects or results of the present invention.
The description of the exemplary embodiments is intended to be read in conjunction with the accompanying drawings, which are to be considered part of the entire written description. In the description, relative terms such as "lower", "upper", "horizontal", "vertical", "above", "below", "up", "down", "top", and "bottom" as well as derivatives thereof (e.g. "horizontally",

"downwardly", "upwardly" etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion.
These relative terms are for convenience of description and do not require that the corresponding apparatus or device be constructed or operated in a particular orientation.
Terms concerning attachments, coupling and the like, such as "connected" and "interconnected", refer to a relationship, wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise.

We claim:
1. A system (200, 300) for supercharging and turbo-compounding of
single-cylinder diesel engine (210, 310), wherein said system (200, 300)
comprises:
• a diesel engine (210, 310) coupled to a power turbine (240) and a supercharger (250);
• said power turbine (240, 340) decoupled from said supercharger (250, 350);
• said supercharger (250, 350) driven by said engine (210, 310) to supply compressed air thereto;
• said power turbine (240, 340) connected downstream the exhaust outlet (214, 314) of said engine (210, 310) for generating additional power from exhaust gases produced therein;
wherein said power turbine (240, 340) and said supercharger (250, 350) are directly coupled to the crankshaft of said engine on either side thereof by means of a power drive.
2. System (200, 300) as claimed in claim 1, wherein said power turbine (240, 340) comprises a direct coupling (218, 318) to said engine (210, 310) via a gear or belt drive.
3. System (200, 300) as claimed in claim 2, wherein said power turbine (240, 340) is configured based on the characteristics of said engine (210, 310).

4. System (200, 300) as claimed in claim 2, wherein said power turbine (240, 340) is an impulse turbine (220, 320) for better extraction of power from the high kinetic energy contained in pulsated or intermittent exhaust gas flow from said engine (210.310).
5. System (200, 300) as claimed in claim 2, wherein said power turbine (220, 320) is un-biased by decoupling thereof from said compressor (230, 330), said compressor being independent of said impulse turbine (220, 320) for power requirements thereof.
6. System (200, 300) as claimed in claim 1, wherein said supercharger (250, 350) comprises a direct coupling (218, 318) to said engine (210, 310) via a gear or belt drive.
7. System (200, 300) as claimed in claim 6, wherein said supercharger (250, 350) comprises a compressor (230,330) directly driven by said engine (210, 310) to supply compressed air thereto to boost air supply thereof.
8. System (200, 300) as claimed in claim 7, wherein said supercharger (250, 350) is directly coupled to the crankshaft of said engine (210, 310) via a gear or belt drive (218, 318).
9. System (300) as claimed in claim 8, wherein an intake plenum (355) is disposed between said supercharger (350) and the intake port (312) of said engine (310); said intake plenum (355) having an inlet manifold (356) for storing compressed air (336) delivered from said compressor (330) to be supplied to said engine (310) whenever required, on opening of said intake port (312).

10. System (300) as claimed in claim 9, wherein said power turbine (340) comprises a convergent nozzle (315) and an impeller (320); said nozzle (320) being disposed between said impeller (320) and the exhaust port (314) of said engine (310); said nozzle (315) directing the exhaust gases towards the blades of said impeller (320) for rotation thereof.
11. System (200, 300) as claimed in claim 1, wherein said power turbine (240, 340) are selected individually depending on the requirements of said engine (210, 310) to make said system (200, 300) operable at any range of speeds, such as low-speeds as well as at high-speeds.