DESC:CROSS REFERENCE TO RELATED APPLICATION
This application is based on and derives the benefit of Indian Provisional Application 202141050707 filed on 5-Nov-2021, the contents of which are incorporated herein by reference.
TECHNICAL FIELD
[001] The embodiments herein generally relate to a forced air induction system of an automobile engine, and more particularly to a mechanical centrifugal supercharger driven by a two stage helical gearbox with high step up ratio for a vehicle engine and a method thereof.
BACKGROUND
[002] One of the biggest global concerns today is the dreadful consequences of climate change including its effects on human health. One of the leading causes is the polluting greenhouse gas emissions (GHG Emissions) from transport sector besides other sectors like industries. The transport sector hugely contributes to the problem through the vehicular exhaust emissions and heavy consumption of fossil fuels which are also challenged with depleting reserves leading to continuously rising prices. Globally, the efforts to mitigate this problem have been focused on enforcing stricter norms for vehicular tailpipe emissions along with norms for fuel economy without a compromise on safety standards. Besides oems adapting expensive methods and technologies to comply with the new norms, it has also led to the focused efforts in migrating from Internal Combustion Engines (ICE) to other perceived cleaner powertrain technologies such as Battery Electric Vehicles (BEV), Plugin Hybrid Electric Vehicles (PHEV), & Fuel Cell Electric Vehicles (FCEV).
[003] Though globally, the large scale adoption of electric vehicles (EV) appears to be a great solution to satisfy emission legislations, but can only be a solution in long term, the EV industry is still caught up in developing technologies for enhanced capacity of batteries, re-charging time, etc to deliver the targets such as range, infrastructure and cost. As EVs are the long term target, a powertrain for mobility which can satisfy the combined demand of current target emissions, fuel economy and safety standards while maintaining sufficient power for customer acceptance is most sought after. Hybrid, PHEV, and I.C. Engines are the preferred options available. Interestingly, all options involve use of an I.C. Engine. Hence it is evident that significant improvement of the I.C. Engine through technological advancements and modifications to cater to target parameters is the need of the hour. Such improvements can be implemented in the new engines. But the greater need is a solution for reducing polluting emissions and wasteful fuel consumption from I.C. Engines, as they are major contributors to the current problem.
[004] It is also the fact that globally in developing and under-developed countries the major problem faced is from the emissions of in-use vehicles whose age ranges from 1yr to 20yrs but has mostly remained unaddressed barring efforts of various governments to contain the problem by implementing ‘Scrapping of Old Vehicles’ which too has not been successful owing to lack of infrastructure, time needed to replace all old version ICE vehicles, its economic impact and political constraints.
[005] Hence besides tightening the norms and regulations for new vehicles, there is a dire need for solutions to control emissions and enhance fuel economy of in-use vehicles.
[006] This situation translates to an urgent need for one stop solution for I.C. Engines that can address simultaneously
• easily adaptable to in-use vehicles
• drastic reduction in exhaust emissions
• better fuel efficiency ( lower fuel consumption)
• safety norms
• better specific power /torque resulting in better driveability
[007] Engine downsizing is a proven approach for achieving increased engine performance through superior fuel efficiency and to significantly reduce tailpipe emissions to address the current environment issues/ emission regulations. Usually, engine downsizing is achieved by reducing the swept volume of the engine and/ or by increasing the power output of the engine by employing a forced air induction system, which means the size of the engine is reduced considerably. Most forced air induction systems of the engine uses a turbocharger which is driven by exhaust gases from the engine. Other forced air induction systems of the engine uses a supercharger which is an air compressor mechanically driven by the engine to provide compressed air to the engine. But the act of physical downsizing of an engine in an existing or in-use vehicle is both technically non feasible and economically non-viable. The current population of in-use vehicles including the recent releases and those aged > 15 years are powered by either Naturally Aspirated (NA) Engines or Turbocharged Engines. Turbocharging though adapted for achieving increased engine performance through superior fuel efficiency and to significantly reduce tailpipe emissions, has not been able to meet the target objectives due its inherent drawbacks.
[008] Turbocharger is subjected to exhaust back pressure on engines thereby increasing pumping losses. Turbo lag occurs because turbochargers rely on the buildup of exhaust gas pressure to drive a turbine of the turbocharger. The exhaust gas pressure of the engine at engine idling, low engine speeds, or low throttle is usually insufficient to drive the turbine of the turbocharger. Only when the engine reaches sufficient speed, the turbine spins fast enough to rotate the turbocharger compressor to provide compressed air with intake pressure above atmospheric pressure.
[009] To overcome these drawbacks, mechanically driven supercharging is adapted. Over the years, the centrifugal superchargers have technically evolved to establish themselves to be a feasible solution. While the degree of urgency and priority of solution being sought is for engines of in-use vehicles. Considering supercharging as prospective solution, adaptability or retrofitability of superchargers using screw-type compressor is ruled out on account of complexities of modification required in the engine structure, bulkiness vs space constraint, and lack of its operability over the entire operating speeds of the engine, thereby leaving mechanically driven centrifugal superchargers as the only choice.
[0010] But the solution for the engines of in-use vehicles that can be considered as a feasible, mandates a Mechanically driven Centrifugal Supercharger with the following features
• A compact gearbox with very high stepup ratio
• Easily adaptable assembly
• Acceptable Noise levels
• Which demands either NIL or least & affordable modifications in the vehicle
• Overall Affordable & economically viable.
[0011] It is known fact that in the gear technology / gear-train art, manufacturing cost of a high precision internal helical gear element needed to achieve a combination of high speed and low noise levels is extremely and prohibitively expensive. Alternatively, such high speeds can only be achieved by a high ratio External Helical Gear drive, however a typical single stage helical gear-train is not desirable due to transmission errors, contact ratio and extremely large size and skewed configuration of the assembly.
[0012] Also, currently, the centrifugal superchargers which are available are not very efficient in comparison to screw type superchargers, as they are incapable of delivering the required/adequate air mass at lower engine speeds. For the centrifugal superchargers to overcome this deficiency they are to be designed to deliver higher mass flow at lower engine speeds, which can be achieved either by large size compressors or by higher compressor speeds at lower engine speeds.
[0013] Therefore, there exists a need for a mechanical centrifugal supercharger with a high step-up ratio and a method, which obviates the aforementioned drawbacks.
OBJECTS
[0014] The principal object of an embodiment herein is to provide a compact centrifugal supercharger for use with engine of vehicles.
[0015] Another object of an embodiment herein is to provide the compact centrifugal supercharger which is a highly responsive, and includes a highly efficient gearbox with very high step up ratio.
[0016] Another object of an embodiment herein is to provide the compact centrifugal supercharger which consists of high speed two-stage helical gearbox, which enhances air boost to the engine whenever there is torque dip at engine crankshaft, which occurs during engine idling, low engine speeds, clutch pedal pressing, shifting gears, braking, and while the vehicle is moving on sloping surface, thereby enabling reduction of polluting emissions and also enhancing fuel efficiency.
[0017] Another object of an embodiment herein is to provide the compact centrifugal supercharger which is retrofitable to existing/in-use engine of the vehicles.
[0018] Another object of an embodiment herein is to provide the compact centrifugal supercharger which can enhance the specific power /torque of an engine and consequently provide better driveability of the vehicle.
[0019] Another object of an embodiment herein is to provide a method of providing a compact centrifugal supercharger for an engine.
[0020] These and other objects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.
BRIEF DESCRIPTION OF DRAWINGS
[0021] The embodiments of the invention are illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein will be better understood from the following description with reference to the drawings, in which:
[0022] Fig.1 depicts a top view of an I.C. Engine arrangement and packaging around an engine block of an existing vehicle, according to embodiments as disclosed herein;
[0023] Fig. 2 depicts a sectional side view of a centrifugal supercharger driven by high speed two-stage helical gear box, according to embodiments as disclosed herein;
[0024] Fig. 3 depicts a front view of the centrifugal supercharger, according to embodiments as disclosed herein;
[0025] Fig.4 depicts a front view of centrifugal supercharger of present invention compared with dimensions of supercharger if it is driven by a single stage helical gearbox, according to embodiments as disclosed herein;
[0026] Fig.5 depicts a sectional side view of the centrifugal supercharger using a double sided impeller compressor, according to embodiments as disclosed herein; and
[0027] Fig.6 is a flowchart depicting a method of providing a compact centrifugal supercharger for an engine, according to embodiments as disclosed herein
DESCRIPTION
[0028] The embodiments herein and the various features and advantageous details thereof are explained more fully with reference to the non-limiting embodiments that are illustrated in the accompanying drawings and detailed in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
[0029] The embodiments herein achieve performance enhancement of an internal combustion engine, especially in existing or in-use vehicles by way of power density and torque enhancement, emission reduction, better and smoother driveability. Additionally, the embodiments herein achieve a compact centrifugal supercharger which consists of high speed two-stage helical gearbox, which enhances air boost to the engine whenever there is torque dip at engine crankshaft, which occurs during engine idling, low engine speeds, clutch pedal pressing and shifting gears, braking, and while the vehicle is moving on sloping surface, thereby enabling reduction of polluting emissions and also enhancing fuel efficiency. Referring now to the drawing, and more particularly to Fig. 1 through Fig. 6, where similar reference characters denote corresponding features consistently throughout the figures, there are shown embodiments.
[0030] Fig. 1 shows the top view of the packaging/arrangement of the I.C. Engine and other accessories in a typical I.C. Engine vehicle including an existing vehicle, where an Engine Block (10) with its inlet and exhaust manifolds attached to the block, A1, A2, A3 and A4 being Front End Accessories Drive (FEAD) by a crankshaft (101). In the case of Turbocharged engines, a turbocharger ”TC” assembly is located near the exhaust manifold consisting of a Turbine “T” and a Compressor “CT”, the entire arrangement being within the limits of rigid body frame /chassis “C” of the vehicle. Generally, an area ”S” shown is an unoccupied and relatively free space available and also the most suitable area/location for retrofitment of the compact supercharger 100, also as the existing ducting from the compressor “CT” of TC can be used for connecting the compressor of supercharger thereby reducing costs and minimizing modifications. Further, the centrifugal supercharger is desired to be disposed within the Area “S” with limiting dimensions width “W” and Length “L”.
[0031] Fig. 2 depicts the sectional side view of the supercharger which may be preferably located in the area “S” in the existing vehicle as shown in Fig.1 and may be mounted only in the manner and position such that input pulley/clutch (102) is in a same plane of the input pulleys of FEAD as shown in Fig. 1. This results in the input /output axis of the supercharger (100) being parallel/in-line with the cylinders of the I.C. Engine, with the total length of the supercharger shown as dimension “Ls” being parallel to “L” of Area “S”. The combination of location, position and alignment in turn mandates the external dimensions of the supercharger 100 as shown in Fig.3 to be less than the limiting dimensions Width “W” and Length “L” of the Area “S”.
[0032] As shown in Fig. 3, dimension “B” is a diameter of the compressor casing. Further to dispose the supercharger 100 within the space available, a compact compressor with dimension “B” being less than dimension “W” may be used. Also due to the phenomenon of “supplied boost increases with square of the rotational speed” in the centrifugal compressor, the demand for a gearbox with high step-up ratio to enhance the input speed at the pulley/clutch (102) which is driven by the engine crankshaft (101) becomes mandatory, specially due to the requirement of spinning the compressor to a very high speed at the low engine speeds (at which input speed of pulley being low) to enable the compressor 200 operate in the higher isentropic and volumetric efficiency.
[0033] A two stage helical Gear box as shown in Fig. 2 includes a step ratio of about 17-18 and outer dimensions of the gearbox “C” not exceeding 11.5 cm and “A” not exceeding 20 cm, and the outer diameter of a corresponding adapted compressor “B” being 17 cm and weighing collectively as supercharger assembly including the clutch assembly around 6.0 kgs. In an embodiment, the speed step-up arrangement SSA is adapted to provide a step ratio of about 17X-18X, when the input shaft 105 receives an input of X. The dimension “A” fits in the vertical dimension of the Area “S” which is not limited by the vehicle. Due to adaptation of two stage gear-train over single stage, the size of the gearbox axially increases however not very significantly. In an embodiment, the size is increased by 4cm axially. However, the space in the axial direction “L” is not a constraint and therefore the increase in the size/dimension “Ls” does not hinder packaging requirements.
[0034] The gears are designed to be ultra-high precision gears with the quality of their teeth profile being DIN 4 and additionally teeth surfaces being coated by special Solid-Lubricant coating such as NASA PS304 or the variants of MiTi-KorolonTM coatings, or derivatives such as Emralon™ or a tooth coating of Molybdenum DisulphideMoS2-WC, cumulatively result in low noise level and low heat generation of the gear-train further resulting in reduction in churning losses.
[0035] Fig. 4 depicts the comparison of the size of the gearbox of the present invention with a gearbox to achieve the same step-up ratio or output speed of the compressor in a single stage arrangement, wherein it can be observed that dimension “B” of the single stage would be 1.7X and similarly dimension “A” would be atleast 2X. Such a large dimension far exceed the limitations of dimensions “W” & depth of the space “S” shown in Fig. 1 and cannot be packaged in the vehicle. Additionally, such single stage arrangement poses challenges of balancing of rotating parts and heavy weight issues.
[0036] In the supercharger assembly 100 shown in Fig. 2, the supercharger includes an input shaft 105, a step-up gearbox arrangement A, an output shaft 110 and a compressor 200. An input from a pulley (not shown) mounted on the crankshaft 101 is received through the pulley/clutch drive 102 which is transferred to the input shaft 105. The input shaft 105 is mounted on a bearing arrangement 103 in a housing 104. The speed step-up arrangement SSA includes a first driving gear 107 which meshes with a first shaft FS, which is mounted in a pair of bearings 106 as shown Fig. 2. The first driving gear 107 defines a bore to receive the input shaft 105 at center portion of the first driving gear 107. The first shaft FS includes a driven gear 108 which meshes with the first driving gear 107. In an embodiment, the first driving gear 107 has a larger diameter than a diameter of the first driven gear 108. The first shaft FS includes a stepped diameter portion which defines a plurality of circumferential teeth to form the first driven gear 108. The first driven gear 108 has a larger diameter than a diameter of said first shaft FS. Further, the SSA includes a second driving gear 109 which is mounted on the first shaft FS which meshes with the output shaft 110. In an embodiment, said second driving gear 109 has a larger diameter than the diameter of the first shaft FS and the diameter of the first driven gear 108. The output shaft 110 is mounted on a bearing arrangement 111 in a housing 112. In an embodiment, the first housing 104 and the second housing 112 are connected together to contain the input shaft 105, the speed step-up arrangement SSA and the output shaft 110. An impeller 202 of a compressor 200 is further retained on the output shaft 110 with help of a nut 203. A volute casing 201 of the compressor 200 is assembled to the housing 112. As is shown, the axes of input and output shafts are offset by a distance “E” not exceeding 6mm, which is near to being coaxial similar to a planetary gearing arrangement. A pressure ratio and a flow rate can be varied in the present supercharger 100 and configured to match the demand specifications of a NA engine without modification of any of the components. This enables easy adaptation to a NA Engine for addressing the emissions problem besides improving fuel economy.
[0037] In an alternate arrangement, the supercharger with the high speed two stage helical gear-box may be coupled to a double sided impeller compressor, as shown in Fig. 5. The supercharger 100 includes one of a single sided impeller compressor 200 and a double sided impeller compressor 300 for torque enhancement, emission reduction, better and smoother driveability.
[0038] Fig.6 is a flowchart depicting a method of providing a compact centrifugal supercharger for an engine, according to embodiments as disclosed herein. A method of providing a compact centrifugal supercharger for an engine is provided. The method 600 includes installing an input shaft 105 in a housing 104 (at step 602). Further, the method 600 includes connecting a speed step-up arrangement SSA to said input shaft 105 (at step 604). Furthermore, the method 600 includes connecting an output shaft 110 to said speed step-up arrangement SSA (at step 606). Additionally, the method 600 includes attaching an impeller to said output shaft 110 (at step 608).
[0039] The technical advantages of the embodiments disclosed herein includes performance enhancement of the internal combustion engine, retrofitable to existing vehicles, power density and torque enhancement, fuel economy, emission reduction, better and smoother driveability.
[0040] 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 understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
,CLAIMS:We claim,
1. A compact supercharger 100 for an engine, comprising:
an input shaft 105 connected to a pulley drive 102 which is turn driven by a pulley mounted on the crankshaft 101 of said engine 10 at one end;
a speed step-up arrangement SSA connected to other end of said input shaft 105;
an output shaft 110 connected to said speed step-up arrangement SSA; and
an impeller 202 connected to a free end of said output shaft 110,
wherein,
said speed step-up arrangement SSA includes:
a first driving gear 107 connected to said input shaft 105;
a first shaft FS defining a first driven gear 108 at one end and connected to a second driving gear 109 at the other end, said first driving gear 107 meshes with said first driven gear 108; and
said second driving gear 109 configured to mesh with said output shaft 110 to deliver a step-up rotational movement to said output shaft 110.

2. The compact supercharger 100 as claimed in claim 1, wherein said first driving gear 107 defines a bore to receive said input shaft 105, said first driving gear 107 has a larger diameter than a diameter of said first driven gear 108.

3. The compact supercharger 100 as claimed in claim 1, wherein
said first shaft FS includes a stepped diameter portion which defines a plurality of circumferential teeth to form said first driven gear 108, said first driven gear 108 has a larger diameter than a diameter of said first shaft FS; and
said second driving gear 109 has a larger diameter than said diameter of said first shaft FS and said diameter of said first driven gear 108.

4. The compact supercharger 100 as claimed in claim 1, wherein said supercharger 100 includes a first housing 104 and a second housing 112 which are connected together to contain said input shaft 105, said speed step-up arrangement SSA and said output shaft 110.

5. The compact supercharger 100 as claimed in claim 1, wherein said supercharger 100 includes:
a compressor 200 which is adapted to receive said impeller 202 in an interior space defined by a volute compressor casing 201; and
said impeller 202 of said compressor 200 is retained on the output shaft 110 through at least one nut 203.

6. The compact supercharger 100 as claimed in claim 1, wherein
said input shaft 105 and said output shaft 110 are coplanar and eccentric to each other;
said input shaft 105 is mounted on a bearing arrangement 103 in said housing 104;
said first shaft FS is mounted within said housing 104 and 112 through a pair of bearings 106;
said output shaft 110 is mounted on a bearing arrangement 111 in said housing 112.

7. The compact supercharger 100 as claimed in claim 1, wherein said first and second gears are at least helical gears with a quality teeth profile being DIN 4, said teeth includes a surface which is being coated by a solid-lubricant coating which are selected from a group having NASA PS304 or the variants of MiTi-KorolonTM coatings, or derivatives such as Emralon™ or a tooth coating of Molybdenum DisulphideMoS2-WC.

8. The compact supercharger 100 as claimed in claim 1, wherein said speed step-up arrangement SSA is adapted to provide a step ratio of about 17X-18X, when the input shaft 105 receives an input of X.

9. The compact supercharger 100 as claimed in claim 1, wherein said supercharger 100 includes one of a single sided impeller compressor 200 and a double sided impeller compressor 300.

10. A method of providing a compact centrifugal supercharger for an engine, comprising:
installing an input shaft 105 in a housing 104;
connecting a speed step-up arrangement SSA to said input shaft 105;
connecting an output shaft 110 to said speed step-up arrangement SSA;
attaching an impeller to said output shaft 110.