TURBO CHARGING SYSTEM FOR IC ENGINES

Field of invention:

The present invention relates to the fields of turbo charging system for an internal combustion (IC) engine of a motor vehicle, and more particularly to a simple construction and flow control mechanism to feed and regulate high pressure and low pressure turbines and switching off the turbines with respect to the flow requirements.

Background of invention:

Turbo chargers are usually provided for charging the intake air into the intake manifold of the IC engine at an increased pressure. Turbo chargers generally comprise an exhaust gas turbine which rotates a gas intake compressor through a connection shaft. The turbine operates by receiving exhaust gas from an internal combustion engine and passing the exhaust gas over the blades of the turbine wheel, and thereby causing the turbine wheel to rotate. This rotational force is used to rotate the compressor shaft and thereby compressing the intake air to a pressure higher than the surrounding atmospheric pressure. The compressed intake air enables to provide increased amount of air drawn into the IC engine and thereby burning more fuel within the cylinder and increasing the engine power output. In turbo charged internal combustion engines, the turbo charging system needs to satisfy a wide range of speed and power output levels and the engine has to operate with good mechanical efficiency. A smaller turbocharger satisfies air flow rates at lower and middle engine speeds but reaches the choke margin of map over-speeding the turbocharger rotor. On the other hand, a bigger turbocharger satisfies air flow requirements at higher engine speeds but fails to build the required boost pressure at lower engine speeds.

Hence both the smaller turbo charger and bigger turbo charger, have their own advantages and drawbacks. To overcome the said drawbacks and to suit wide range engine operation the ideal solution would be to have a combination of both. Multi stage turbo charging, usually two stage turbo charging is done by selecting one smaller turbocharger and one bigger turbo charger and connecting them together. A two staged turbo charged engine system comprises a high pressure turbo charger and a low pressure turbo charger, both having a compressor and a turbine. High pressure turbo charger and low pressure turbo charger are arranged such that, the turbochargers are used in combination or in single for charging the air into the engine, with respect to the engine speeds and to suit the engine operation requirements. Normally a control device is provided to channellize the flow of gas to high pressure turbine and low pressure turbine.

FIGS. 1 and 2 illustrate schematic diagram of conventional arrangement of turbo charging system of an IC engine 1 having an intake manifold 2 and exhaust manifold 3, in which a low pressure turbine (LPT) 4 and a high pressure turbine (HPT) 5 are assembled. A low pressure compressor (LPC) 6 and a high pressure compressor 7 are respectively assembled to the turbines 4 and 5 through shafts. The high pressure turbine 5 is placed upstream to the exhaust manifold and the low pressure turbine 4 is placed downstream. A high pressure turbine by-pass (HPT by-pass) 8 acts as a regulator and controls the boosting pressure within high pressure stage. A low pressure turbine waste-gate (LPTWG) 9 decreases the low pressure turbocharger speed and avoids its over speeding. In this arrangement the controlling of boost pressure is maintained by switching off the high pressure turbine (HPT) 4 at higher engine speeds. A high pressure compressor by-pass (HPC by-pass) 10 enables by-passing of high pressure stage together with high pressure turbine by-pass (HPT by-pass) 8 and enables to "switch off the high pressure turbine 5, at high engine speeds, as the high pressure compressor 7 is too small for extensive mass flow. This arrangement allows for controlling and switching off the turbines between the high pressure stage and low pressure stage, with the help of regulator and by- pass elements in the turbo charging system.

With respect to the conventional turbo charging system arrangement, it is necessary to provide regulators and by-pass elements to manage the controlling the flow and switching off the turbines, which increases number of parts and requires more space. The conventional turbo charging arrangement also suffers complex control mechanism and it is difficult to have precise flow control, and such arrangement will affect the turbo charging system and will have an undesired effect on engine performance and power output. Therefore, it is desirable to provide an improved system developed for controlling and feeding the turbines, which is capable to address and overcome the above disadvantages of conventional turbo charging systems.

Object of the invention

The object of the present invention is to provide a simple flow control mechanism to feed and regulate high pressure and low pressure turbines and switching them with respect to the flow requirements. Another object of the present invention is to improve the air flow characteristics and engine benefits for a wider range with a simple flow control and regulation mechanism on the two stage turbo charging system. A further object of the present invention is to provide a simple flow control mechanism to feed and regulate the high pressure and low pressure turbines in a cost effective manner.

Summary of the invention

The present invention, which achieves the objectives, relates to a turbo charging system for an IC engine comprises a turbocharger having a high pressure turbine and a low pressure turbine, in which a high pressure compressor and low pressure compressor are coupled together respectively. The Low pressure turbine is bigger in size and the high pressure turbine is relatively smaller in size. The turbines and the compressors are connected through respective shafts which transmits the mechanical energy received in the turbines to the compressors. The turbine is operated using the exhaust gas from the engine to drive the compressor, which pumps the charged air by compressing fresh air received from an air inlet unit. According to the invention, the low pressure turbine is placed in the upstream position to the exhaust manifold and the high pressure turbine is placed at the downstream position. The complicated controllers are eliminated and the waste gate of low pressure turbine (LPTWG) is used as a regulator to effectively manage the flow control in the turbo charging system. Low pressure turbine waste gate acting as a regulator is vacuum controlled to have precise flow control in the switching off activity with the low pressure and the high pressure turbines in the turbo charging system.

Further, the waste gate is set fully open at low engine speed operation, and thereby allowing most of the exhaust gases to fall on the high pressure turbine (HPT) placed at downstream position of turbo charging system. This allows the high pressure turbine (HPT) to build adequate boost pressures due to its smaller size. At higher speeds the LPTWG is closed and the exhaust gases are allowed to fall on the low pressure turbine (LPT). The low pressure turbine (LPT) will be able to meet the higher air mass flow requirements of the engine due to its bigger size. According to this invention, this improved design of turbo charging system allows the exhaust gas entry into the turbines using the waste gate port of low pressure turbine to feed the high pressure turbine at lower engine speeds and to switch off the high pressure turbine at higher engine speeds by closing the waste gate port.

The low pressure turbine waste gate (LPTWG) is the only regulator used to manage the flow control in the turbo charging system, which makes the turbo charging system to eliminate the usage of by-pass regulators and making the system construction simple and cost effective. In addition, this improved turbo charging system will enables to increase the engine's rated power and power-to-weight ratio. This two stage turbo charging system will enable to lower the fuel consumption and allows meeting higher emission norms.

Brief description of drawings
Referring now to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same.

FIG. 1 shows a schematic diagram of a conventional turbo charging system for a turbocharged IC engine, in accordance with a prior art;

FIG. 2 illustrates a schematic arrangement of a conventional turbo charging system for a turbocharged IC engine, in accordance with a prior art;

FIG. 3 shows a schematic diagram of an improved turbo charging system for a turbocharged IC engine, in accordance with an exemplary embodiment of the present invention.

FIG. 4 shows a graphical representation of increased boost pressure with the turbo charging system, in accordance to the present invention.

FIG. 5 shows a graphical representation of improved air fuel ratio with the turbo charging system, in accordance to the present invention.

FIG. 6 shows a graphical representation of reduced smoke number with the turbo charging system for a turbocharged IC engine, in accordance with an exemplary embodiment of the present invention.

Detailed description:

The present invention relates to the turbo charging system for an internal combustion (IC) engine having a flow control mechanism to feed and regulate the high pressure turbine and the low pressure turbine and switching off the turbines with respect to the flow requirements and the engine speeds. FIG. 3 shows a schematic diagram of an improved turbo charging system for a turbocharged IC engine in accordance with an exemplary embodiment of the present invention. The present invention generally relates to a new and improved turbo charging system, particularly a simple construction and flow control mechanism to feed and regulate the high pressure and low pressure turbines and switching off the turbines with respect to the flow requirements. Hereafter, the system can be referred as turbo charging system only for the purpose of explanation.

This turbo charging system is associated with an internal combustion engine (1), which is assembled with an intake manifold (2) and an exhaust manifold (3). The turbo charging system is arranged with a low pressure turbine LPT (4) and a high pressure turbine HPT (5). A low pressure compressor LPC (6) and a high pressure compressor HPC (7) are connected to the low pressure turbine LPT (4) and high pressure turbine HPT (5) respectively. The low pressure turbine LPT (4) and the high pressure turbine HPT (5) are connected to the low pressure compressor LPC (6) and high pressure compressor HPC (7) through the shafts (8) and (9) respectively.

The exhaust manifold (3) of the engine (1) is connected with the low pressure turbine LPT (4) and high pressure turbine HPT (5) of the turbo charging system, so that the exhaust gas from the exhaust manifold (3) of the engine (1) is passed through to run the turbines LPT (4) and HPT (5), which in turn drives the compressors LPC (6) and HPC (7) of the turbo charging system. The Low pressure turbine LPT (4) is relatively bigger in size and the high pressure turbine HPT (5) is smaller in size. The low pressure turbine LPT (4) and high pressure turbine HPT (5) are operated using the exhaust gas from the exhaust manifold (3) of the engine (1) to drive the compressors LPC (6) and HPC (7), which pumps the charged air by compressing the fresh air received from an air inlet unit (11).

The low pressure turbine LPT (4) is placed in an upstream position and the high pressure turbine HPT (5) is paced at the downstream position. A waste gate (10) is provided for the low pressure turbine (LPTWG) which acts as a regulator to effectively manage the flow control in the turbo charging system. The high pressure compressor HPC (9) of the turbo charging system receives fresh air from atmosphere through an air cleaner, which acts as an air inlet unit and provides fresh atmospheric air (11). The Low pressure turbine LPT (4) and the high pressure turbine HPT (5) are operated by the exhaust gas coming out from the exhaust manifold (3), and the compressors LPC (6) and HPC (7) of the turbo charging system are driven by the respective turbines to compress the fresh air (11) from the air inlet and thereby producing charged air (12), which is passed to the engine (1) though the intake manifold (2).

In operation, the low pressure turbine waste gate (10) acting as regulator is set fully open at low engine speed operation, and allows most of the exhaust gases to fall on the high pressure turbine HPT (5) placed at downstream position of turbo charging system. This arrangement allows the high pressure turbine HPT (5) to build adequate boost pressures due to its smaller size. At higher engine speeds the LPTWG (10) is closed and the exhaust gases are allowed to fall on the low pressure turbine LPT (4). The low pressure turbine LPT (4) will be able to meet the higher air mass flow requirements of the engine owing to its bigger size. Thus providing a turbo charging system which allows the exhaust gas entry into the selective turbines using the waste gate port to feed the high pressure turbine at lower engine speeds and switching off the high pressure turbine at higher engine speeds by closing the waste gate port.

FIG. 4 shows a graphical representation of increased boost pressure with the turbo charging system, in accordance with an exemplary embodiment of the present invention. The waste gate directs the gas flow such that the high pressure turbine HPT (5) builds adequate boost pressures at lower engine speeds and the gas flow is directed to the low pressure turbine LPT (4) at lower engines speeds. This makes the system to increase the boost pressure as shown in the graph. This increase in boost pressure will enable the system to improve the engine power output characteristics over wider load conditions and increase the engine power-to-weight ratio. The present invention allows improving the air flow requirements and provides benefits for a wider range with this simple flow control and regulation mechanism.

FIG. 5 shows a graphical representation of improved air fuel ratio with the turbo charging system. The low pressure compressor and high pressure compressor works with respect to the regulated exhaust gas flow in the respective turbines, and pressurise the fresh air passing through the inlet manifold, thus enabling the system to improve air flow characteristics. FIG. 6 shows a graphical representation of reduced smoke number with the turbo charging system for a turbocharged IC engine. The present invention of two stage turbo charging system enables the charged air to get compressed and provides increased amount of air drawn into the IC engine with respect to the engine speed requirements, thus achieving optimum level of combustion characteristics and meeting higher emission norms with reduced smoke number.

The turbo charging system, according to the present invention allows the exhaust gas entry into the turbines using the waste gate port of low pressure turbine to feed the high pressure turbine at lower engine speeds and to switch off the high pressure turbine at higher engine speeds by closing the waste gate port. The low pressure turbine waste gate is the only regulator used to manage the flow control in the turbo charging system, which makes the turbo charging system to eliminate the usage of by-pass regulators and making the system construction simple and cost effective. In addition, this improved turbo charging system enables to increase the engine's rated power and power-to-weight ratio. This two stage turbo charging system will enable to lower the fuel consumption and allows meeting higher emission norms.

The turbo charging system works with simple control elements like waste gate provided on the low pressure turbine to manage the flow control in this turbo charging system, and does not employ any complex control elements such as usage of by-pass regulators to direct the flow control in this turbo charging system, thus providing a turbo charging system with simple construction and making the system cost effective. The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

We Claim:

1. A system for regulating flow control in a turbo charger for an internal combustion engine comprising, a high pressure turbine (5) and a high pressure compressor (7) coupled together through a shaft (9), a low pressure turbine (4) and a low pressure compressor (6) coupled together through another shaft (8); wherein said low pressure turbine (4) is placed in an upstream position and said high pressure turbine (5) is placed in a downstream position; at least one waste gate (10) for the low pressure turbine (4) acting as a controller and regulating the exhaust gas flow with the high pressure turbine (5) and the low pressure turbine (4), wherein the exhaust gas from exhaust manifold (3) of the engine (1) is passed through the waste gate (10) to feed and switch off the turbines with respect to the engine speed; wherein at lower engine speeds the waste gate (10) fully opens and allows the exhaust gases towards the high pressure turbine (5) to build adequate boost pressure in the engine, and at higher engine speeds the waste gate (10) gets closed and allows the exhaust gases towards the low pressure turbine (4) to meet higher air mass flow requirements for the engine.

2. The system as claimed in claim 1, wherein said waste gate (10) of the low pressure turbine (4) is vacuum controlled to provide precise flow control with wider speed range.

3. The system as claimed in claim 1, wherein said low pressure turbine (4) is bigger in size and said high pressure turbine (5) is smaller in size.

4. The system as claimed in claim 1, wherein said waste gate (10) switch off the exhaust gas flow to said high pressure turbine (5) at higher engine speeds by closing the waste gate port.

5. The system as claimed in claim 1, wherein at lower engine speeds, said waste gate (10) allows exhaust gas flow to the high pressure turbine (5) to build adequate boost pressures.

6. The system as claimed in claim 1, wherein said turbines drive said compressors (6) for compressing the fresh air (11) from the air inlet and produce charged air (12) to said intake manifold (2).

7. The system as claimed in claim 1, wherein said shafts (8, 9) transmit the mechanical energy received in said turbines (4, 5) to said compressors (6), to pump the charged air (12) by compressing fresh air (11) received from said air inlet unit.

8. The system as claimed in claim 1, wherein said intake air flows from said compressor (6) to said intake manifold (2) of the engine (1).

9. The system as claimed in claim 1, wherein said exhaust gas flows from exhaust manifold (3) to the turbines through said waste gate (10).