Title of Invention	AN ARRANGEMENT FOR CONTROLLING IDLE SPEED OF AN ENGINE
Abstract	This invention relates to a device that achieves control over engine idling speed for gas engines. The engine idle speed control mechanism consists of separate means for increasing and controlling the quantity of the mixture flow at idling. The throttle plate is provided with the bleed holes whose flow area can be varied. The external idle air bypass consists of a parallel path for gas air mixture flow under closed throttle condition. The idle speed controller may consist of one or more or a combination of these means. In order to have simplicity and reliability of operation with lower cost of the device, mechanical means of idle mixture control are proposed.

Title of Invention

AN ARRANGEMENT FOR CONTROLLING IDLE SPEED OF AN ENGINE

Abstract

This invention relates to a device that achieves control over engine idling speed for gas engines. The engine idle speed control mechanism consists of separate means for increasing and controlling the quantity of the mixture flow at idling. The throttle plate is provided with the bleed holes whose flow area can be varied. The external idle air bypass consists of a parallel path for gas air mixture flow under closed throttle condition. The idle speed controller may consist of one or more or a combination of these means. In order to have simplicity and reliability of operation with lower cost of the device, mechanical means of idle mixture control are proposed.

Full Text	FORM 2 THE PATENTS ACT 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See Section 10; rule 13) TITLE OF THE INVENTION An Arrangement For Controlling Idle Speed Of An Engine APPLICANTS TATA MOTORS LIMITED, an Indian company having its registered office at Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001 Maharashtra, India INVENTORS Mr. Dattatraya R. Katkar, Mr. Deepak S. Kulkarni both Indian Nationals of TATA MOTORS LIMITED, an Indian company having its registered office at Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai 400 001 Maharashtra, India PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner in which it is to be performed FIELD OF INVENTION This invention relates a device for controlling idling speed of carburetion type engines. More particularly, it relates to gas engines which do not have a separate means of controlling idling speed. This device can be attached to mono-fuel, bi-fuel gas engines. BACKGROUND OF INVENTION Natural gas, LPG are being considered as an alternate fuels for conventional fuels. The drivers for use of natural gas, LPG in engines are i) Environmental aspects ii) Shift to non conventional fuel iii) Operating economics. Due to above reasons engines operating on Natural gas, LPG have a great significance in Indian context. Currently, most of the gas operated vehicles in India make use of carbureted type of system. These engine fall under either of the two categories - i) Existing base gasoline engines are made to run on natural gas in bi-fuel mode, ii) Modifying existing diesel engines to run on dedicated CNG mode of operation. Unlike ECU controlled MPFI engines, carburatted gas engines do not have separate mechanism for idle speed control. Idling condition of the engine is the first interaction of the customer with the vehicle. Similarly increased city driving, stops at signals etc. also necessitate the reliable engine idle operation. At present, engine idle speed is maintained by either of the two ways - i) Mechanically opening the throttle to a predetermined angle by a screw. ii) Manually opening the throttle through accelerator pedal. It is worthwhile to note that engine idle air flow is @ 10 % of the rated air flow. The throttle is sized for air flow at rated speed of the engine. Thus, this method results in a very coarse control on engine idle speed. Similarly, the position of idle screw may also vary in field due to vibration during vehicle operation leading to engine stalling or higher engine idle speed. The idle speed of an S.I engine is an outcome of flow of air into the engine under closed throttle condition. The air flow into the engine under closed throttle is mainly through - i) Leakage past closed throttle, ii) Flow through partially opened throttle (if opened through adjusting screw), iii) Flow through bypass passage. Typically, idle air flow requirement is less than 10% of the rated air flow and at the same time the idle speed of an engine is very sensitive to air flow. The requirement of engine idle air flow varies depending upon - i) Condition of the engine, ii) Ambient conditions, iii) Auxiliary load on the engine. The engine fuel consumption at idle condition depends upon idle speed, idle air fuel ratio, and other parameters like engine friction. Increased city traffic has necessitated precise idle speed control for the engines. Considerable amount of work has been done in idle speed control mechanisms for carbureted gasoline engines. In case of carbureted gasoline the engine idle speed control features are already developed by carburetor manufacturers. Most of these are well documented. These include separate idle air and fuel flow arrangements. The carbureted gasoline engines have become obsolete on account of emission and are replaced by MPFI engines which have elaborate ECU controls to maintain engine idle speed. These include stepper motor controlled idle air bypass with water temperature correction. Carbureted gas engines are still in use and will continue to be in use since, these engines in their simplest form are capable of meeting current and future emission regulations. US 4,438745 teaches that an engine idle speed control device consists of throttle body which has main rotatable throttle plate and additionally a shuttle type side valve is mounted on the main throttle plate. The shuttle plate can be aligned or mis aligned with the apertures on the main throttle plate. This adjustment in turn controls the volume of the air, air/ fuel ratio through the throttle plate into the engine regardless of altitude or position of the main throttle plate. The flow through the apertures supplements the main flow. The shuttle plate is moved by power means energized by electrical signals from microprocessor. The microprocessor gets an input from operating conditions of the engine to decide the position of the side valve to maintain an idle speed schedule. US 4,212,272 teaches that an idle speed control device of a compact size has a miniature D.C. motor operably connected by a speed reducing gear train to drive a threaded shaft to adjust the position of the throttle stop of an engine throttle valve. Thus controlling an engine idle speed. Initially, the throttle stop is moved by the throttle lever to close a normally open switch within the device. This enables the motor operation only during idle and when the throttle stop reaches a maximum throttle valve opening position the threaded shaft disengages from the gear train and reengages when the motor reverses. It is worthwhile to note that the idle speed control systems employed in MPFI gasoline systems can not be employed to carbureted gas engines. The theory and fundamentals of idle speed control remain unchanged but the practice will differ. Present invention deals with simple, cost effective methods of maintaining idle speed for carbureted gas engines. OBJECTS OF INVENTION The main object of this invention is to provide an arrangement for controlling idling speed of carbureted gas engines which can be retrofitted. Another object of this invention is to provide designed, precise and controlled means for controlling idle rpm carbureted gas engines. Yet another object of this invention is to provide the engine idle speed control by built in design as well as through an add on design and through mechanical control with driver. Yet another object of this invention is to provide low cost mechanical device for controlling engine idle speed. SUMMARY OF INVENTION This invention relates to a device that results in improved idling performance of the engine. The device consists of additional means of regulating the flow of air fuel mixture under idling condition. The regulated mixture flow results in stable engine idle operation. The control over air fuel mixture flow is achieved by one or more or combination of the means given below - i) Controlled internal bleed ii) Bypass a) Variable opening bypass controlled by mechanical means b) Variable opening bypass by electromechanical means. According to this invention an arrangement for controlling idle speed of an engine, the arrangement comprising, an air intake system having an intake manifold, a throttle body assembly affixed to said intake manifold, said throttle body assembly includes a throttle plate attached to a throttle shaft, said throttle plate having at least one orifice, and at least one hinged flap located on said throttle plate for covering said orifice thereby controlling the flow area. According to another embodiment of the present invention an arrangement for controlling idle speed of an engine, the arrangement comprising, An air intake system having an intake manifold, a throttle body assembly affixed to said intake manifold, said throttle body assembly includes a throttle plate having at least one orifice attached to a throttle shaft, at least one hinged flap located on said throttle plate for covering said orifice thereby controlling the flow area, and a variable volume air bypass channel connecting the intake manifold on opposite sides of the throttle body for the bypass of air around throttle body. BRIEF DESCRIPTION OF DRAWINGS Figure 1 shows arrangement of flaps for varying air bleed passage area in accordance with present invention. Figure 2 shows the combination of variable internal bleed and variable external bypass with manual control Figure 3 shows the combination of variable internal bleed and variable external bypass with electromechanical control DESCRIPTION OF PREFERRED EMBODIMENTS 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 Referring to figures 1 to 3, Fig 1 shows the arrangement for adjusting the internal bleed passage flow area. At the front portion of the inlet manifold a throttle body is attached. Basically the throttle body of comprises of circular plate whose angular position is changed through accelerator linkage. Gas induction device is attached to the throttle. In accordance with this invention the throttle plate (11) is attached to a throttle shaft (13). Orifices (12) are provided on the throttle plate. The size of the holes is decided based on the engine size or application. The other possible arrangement is to fit the orifice inserts at the drilled holes. This arrangement gives added flexibility for controlling the flow area. The flaps (14) are hinged (15) to the throttle plate in such away that by suitably adjusting the orientation of flap the flow to the engine under closed throttle can be controlled. This arrangement of adjusting the flow area makes the arrangement suitable for retrofitment as well as suitable for different capacity engines. Fig 2 shows a combination of internal bleed and external manually variable bypass arrangement. The internal variable air bypass comprises of a controlled diameter orifice (12) along with hinged flap (14) regulates the mixture flow past throttle under closed throttle operation. The external variable volume air bypass comprises of a bypass tube (23) attached to the intake system through adapters (22). The bypass tube (23) is connecting the intake manifold on opposite sides of the throttle body for the bypass of air around throttle body. Manually adjustable remote operated flow control valve (24) is fitted into the bypass tube. The position of flow control valve is adjusted by a linkage (26) similar to choke cable. Thus the position of the flow control valve can be varied by the driver himself while sitting in his seat. This arrangement is designed for applications when the auxiliary loads on the engine vary during the operation. For example electrical loads, air conditioning load etc. This arrangement can be adapted as an add-on to any engine without major modifications in the intake system components. Fig 3 shows a combination of internal bleed and external electromechanically controlled bypass arrangement. The internal variable air bypass comprises of a controlled diameter orifice (12) along with hinged flaps (14) regulates the mixture flow past throttle under closed throttle operation. The external variable air bypass comprises of a bypass tube (23) attached to the intake system through adapters (22). The bypass tube (23) is connecting the intake manifold on opposite sides of the throttle body for the bypass of air around throttle body. A stepper motor (31) is fitted into the bypass tube. The opening position of the stepper motor is controlled by an electronic controller (32) based on engine speed signal and set value of engine idle speed. The electronic controller (32) comprises of a comparator which compares the engine speed value with the set value. Based on the difference between actual idle speed and the set point the signal is given to the stepper motor. Thus the position of the flow control valve is controlled automatically. This arrangement is designed for applications where the auxiliary load on the engine vary during the operation and the adjustment is required without the driver intervention.. This arrangement can be adapted as an add on to any engine without major modifications in the intake system components Advantages 1. Idle speed adjustment mechanism designed for carbureted gas engines both dedicated and bi-fuel engines operating with natural gas or LPG as a second fuel. 2. The adjustment mechanism is suitable for retrofitment in existing vehicles. 3. The engine idle speed adjustment is possible by the driver from cabin sitting in his seat. 4. Engine idle speed adjustment mechanism that is suitable for engine of any size and capacity by varying the internal bleed area and y pass flow area 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. An arrangement for controlling idle speed of an engine, the arrangement comprising, An air intake system having an intake manifold, a throttle body assembly affixed to said intake manifold, said throttle body assembly includes a throttle plate attached to a throttle shaft, said throttle plate having at least one orifice, and at least one hinged flap located on said throttle plate for covering said orifice thereby controlling the flow area. 2. An arrangement for controlling idle speed of an engine, the arrangement comprising, An air intake system having an intake manifold, a throttle body assembly affixed to said intake manifold, said throttle body assembly includes a throttle plate attached to a throttle shaft, said throttle plate having at least one orifice, at least one hinged flap located on said throttle plate for covering said orifice thereby controlling the flow area, and a variable volume air bypass channel connecting the intake manifold on opposite sides of said throttle body for the bypass of air around throttle body. 3. The arrangement for controlling idle speed of an engine as claimed in either claim 1 or 2, wherein said flap can be rotated on a hinge to cover the orifice to reduce or increase flow area. 4. The arrangement for controlling idle speed of an engine as claimed in claim 2, wherein said air bypass channel having a valve to control the air flow. 5. The arrangement for controlling idle speed of an engine as claimed in claim 4, wherein said valve activated manually. 6. The arrangement for controlling idle speed of an engine as claimed in claim 4, wherein said valve activated by electromechanically. 7. The arrangement for controlling idle speed of an engine as claimed in claim 6, wherein said valve activated by an electronic controller based on engine speed. 8. The arrangement for controlling idle speed of an engine as claimed in claim 2, wherein said variable volume air bypass channel can be retrofitted on intake manifold using adaptors. 9. The arrangement for controlling idle speed of an engine substantially as herein described with reference to accompanying drawings. ABSTRACT "An Arrangement For Controlling Idle Speed Of An Engine" Figure 1 This invention relates to a device that achieves control over engine idling speed for gas engines. The engine idle speed control mechanism consists of separate means for increasing and controlling the quantity of the mixture flow at idling. The throttle plate is provided with the bleed holes whose flow area can be varied. The external idle air bypass consists of a parallel path for gas air mixture flow under closed throttle condition. The idle speed controller may consist of one or more or a combination of these means. In order to have simplicity and reliability of operation with lower cost of the device, mechanical means of idle mixture control are proposed.

Full Text

FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION An Arrangement For Controlling Idle Speed Of An Engine
APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Mr. Dattatraya R. Katkar, Mr. Deepak S. Kulkarni
both Indian Nationals
of TATA MOTORS LIMITED,
an Indian company having its registered office
at Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION The following specification particularly describes the invention and the manner
in which it is to be performed

FIELD OF INVENTION
This invention relates a device for controlling idling speed of carburetion type engines. More particularly, it relates to gas engines which do not have a separate means of controlling idling speed. This device can be attached to mono-fuel, bi-fuel gas engines.
BACKGROUND OF INVENTION
Natural gas, LPG are being considered as an alternate fuels for conventional fuels. The drivers for use of natural gas, LPG in engines are i) Environmental aspects ii) Shift to non conventional fuel iii) Operating economics. Due to above reasons engines operating on Natural gas, LPG have a great significance in Indian context. Currently, most of the gas operated vehicles in India make use of carbureted type of system. These engine fall under either of the two categories -
i) Existing base gasoline engines are made to run on natural gas in bi-fuel
mode, ii) Modifying existing diesel engines to run on dedicated CNG mode of
operation.
Unlike ECU controlled MPFI engines, carburatted gas engines do not have separate mechanism for idle speed control. Idling condition of the engine is the first interaction of the customer with the vehicle. Similarly increased city driving, stops at signals etc. also necessitate the reliable engine idle operation. At present, engine idle speed is maintained by either of the two ways -
i) Mechanically opening the throttle to a predetermined angle by a screw.
ii) Manually opening the throttle through accelerator pedal.

It is worthwhile to note that engine idle air flow is @ 10 % of the rated air flow. The throttle is sized for air flow at rated speed of the engine. Thus, this method results in a very coarse control on engine idle speed. Similarly, the position of idle screw may also vary in field due to vibration during vehicle operation leading to engine stalling or higher engine idle speed.
The idle speed of an S.I engine is an outcome of flow of air into the engine under closed throttle condition. The air flow into the engine under closed throttle is mainly through - i) Leakage past closed throttle, ii) Flow through partially opened throttle (if opened through adjusting screw), iii) Flow through bypass passage.
Typically, idle air flow requirement is less than 10% of the rated air flow and at the same time the idle speed of an engine is very sensitive to air flow.
The requirement of engine idle air flow varies depending upon - i) Condition of the engine, ii) Ambient conditions, iii) Auxiliary load on the engine. The engine fuel consumption at idle condition depends upon idle speed, idle air fuel ratio, and other parameters like engine friction. Increased city traffic has necessitated precise idle speed control for the engines.
Considerable amount of work has been done in idle speed control mechanisms for carbureted gasoline engines.
In case of carbureted gasoline the engine idle speed control features are already developed by carburetor manufacturers. Most of these are well documented. These include separate idle air and fuel flow arrangements. The carbureted gasoline engines have become obsolete on account of emission and are replaced by MPFI engines which have elaborate ECU controls to maintain engine idle speed. These include stepper motor controlled idle air bypass with water temperature correction.

Carbureted gas engines are still in use and will continue to be in use since, these engines in their simplest form are capable of meeting current and future emission regulations.
US 4,438745 teaches that an engine idle speed control device consists of throttle body which has main rotatable throttle plate and additionally a shuttle type side valve is mounted on the main throttle plate. The shuttle plate can be aligned or mis aligned with the apertures on the main throttle plate. This adjustment in turn controls the volume of the air, air/ fuel ratio through the throttle plate into the engine regardless of altitude or position of the main throttle plate. The flow through the apertures supplements the main flow. The shuttle plate is moved by power means energized by electrical signals from microprocessor. The microprocessor gets an input from operating conditions of the engine to decide the position of the side valve to maintain an idle speed schedule.
US 4,212,272 teaches that an idle speed control device of a compact size has a miniature D.C. motor operably connected by a speed reducing gear train to drive a threaded shaft to adjust the position of the throttle stop of an engine throttle valve. Thus controlling an engine idle speed. Initially, the throttle stop is moved by the throttle lever to close a normally open switch within the device. This enables the motor operation only during idle and when the throttle stop reaches a maximum throttle valve opening position the threaded shaft disengages from the gear train and reengages when the motor reverses.
It is worthwhile to note that the idle speed control systems employed in MPFI gasoline systems can not be employed to carbureted gas engines. The theory and fundamentals of idle speed control remain unchanged but the practice will differ. Present invention deals with simple, cost effective methods of maintaining idle speed for carbureted gas engines.

OBJECTS OF INVENTION
The main object of this invention is to provide an arrangement for controlling idling speed of carbureted gas engines which can be retrofitted.
Another object of this invention is to provide designed, precise and controlled means for controlling idle rpm carbureted gas engines.
Yet another object of this invention is to provide the engine idle speed control by built in design as well as through an add on design and through mechanical control with driver.
Yet another object of this invention is to provide low cost mechanical device for controlling engine idle speed.
SUMMARY OF INVENTION
This invention relates to a device that results in improved idling performance of the engine. The device consists of additional means of regulating the flow of air fuel mixture under idling condition. The regulated mixture flow results in stable engine idle operation. The control over air fuel mixture flow is achieved by one or more or combination of the means given below -
i) Controlled internal bleed
ii) Bypass
a) Variable opening bypass controlled by mechanical means
b) Variable opening bypass by electromechanical means.
According to this invention an arrangement for controlling idle speed of an engine, the arrangement comprising, an air intake system having an intake manifold, a

throttle body assembly affixed to said intake manifold, said throttle body assembly includes a throttle plate attached to a throttle shaft, said throttle plate having at least one orifice, and at least one hinged flap located on said throttle plate for covering said orifice thereby controlling the flow area.
According to another embodiment of the present invention an arrangement for controlling idle speed of an engine, the arrangement comprising, An air intake system having an intake manifold, a throttle body assembly affixed to said intake manifold, said throttle body assembly includes a throttle plate having at least one orifice attached to a throttle shaft, at least one hinged flap located on said throttle plate for covering said orifice thereby controlling the flow area, and a variable volume air bypass channel connecting the intake manifold on opposite sides of the throttle body for the bypass of air around throttle body.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 shows arrangement of flaps for varying air bleed passage area in accordance with present invention.
Figure 2 shows the combination of variable internal bleed and variable external bypass with manual control
Figure 3 shows the combination of variable internal bleed and variable external bypass with electromechanical control
DESCRIPTION OF PREFERRED EMBODIMENTS
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

Referring to figures 1 to 3,
Fig 1 shows the arrangement for adjusting the internal bleed passage flow area. At the front portion of the inlet manifold a throttle body is attached. Basically the throttle body of comprises of circular plate whose angular position is changed through accelerator linkage. Gas induction device is attached to the throttle. In accordance with this invention the throttle plate (11) is attached to a throttle shaft (13). Orifices (12) are provided on the throttle plate. The size of the holes is decided based on the engine size or application. The other possible arrangement is to fit the orifice inserts at the drilled holes. This arrangement gives added flexibility for controlling the flow area. The flaps (14) are hinged (15) to the throttle plate in such away that by suitably adjusting the orientation of flap the flow to the engine under closed throttle can be controlled. This arrangement of adjusting the flow area makes the arrangement suitable for retrofitment as well as suitable for different capacity engines.
Fig 2 shows a combination of internal bleed and external manually variable bypass arrangement. The internal variable air bypass comprises of a controlled diameter orifice (12) along with hinged flap (14) regulates the mixture flow past throttle under closed throttle operation. The external variable volume air bypass comprises of a bypass tube (23) attached to the intake system through adapters (22). The bypass tube (23) is connecting the intake manifold on opposite sides of the throttle body for the bypass of air around throttle body. Manually adjustable remote operated flow control valve (24) is fitted into the bypass tube. The position of flow control valve is adjusted by a linkage (26) similar to choke cable. Thus the position of the flow control valve can be varied by the driver himself while sitting in his seat. This arrangement is designed for applications when the auxiliary loads on the engine vary during the operation. For example electrical loads, air conditioning

load etc. This arrangement can be adapted as an add-on to any engine without major modifications in the intake system components.
Fig 3 shows a combination of internal bleed and external electromechanically controlled bypass arrangement. The internal variable air bypass comprises of a controlled diameter orifice (12) along with hinged flaps (14) regulates the mixture flow past throttle under closed throttle operation. The external variable air bypass comprises of a bypass tube (23) attached to the intake system through adapters (22). The bypass tube (23) is connecting the intake manifold on opposite sides of the throttle body for the bypass of air around throttle body. A stepper motor (31) is fitted into the bypass tube. The opening position of the stepper motor is controlled by an electronic controller (32) based on engine speed signal and set value of engine idle speed. The electronic controller (32) comprises of a comparator which compares the engine speed value with the set value. Based on the difference between actual idle speed and the set point the signal is given to the stepper motor. Thus the position of the flow control valve is controlled automatically. This arrangement is designed for applications where the auxiliary load on the engine vary during the operation and the adjustment is required without the driver intervention.. This arrangement can be adapted as an add on to any engine without major modifications in the intake system components
Advantages
1. Idle speed adjustment mechanism designed for carbureted gas engines both dedicated and bi-fuel engines operating with natural gas or LPG as a second fuel.
2. The adjustment mechanism is suitable for retrofitment in existing vehicles.

3. The engine idle speed adjustment is possible by the driver from cabin sitting in his seat.
4. Engine idle speed adjustment mechanism that is suitable for engine of any size and capacity by varying the internal bleed area and y pass flow area
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. An arrangement for controlling idle speed of an engine, the arrangement comprising, An air intake system having an intake manifold, a throttle body assembly affixed to said intake manifold, said throttle body assembly includes a throttle plate attached to a throttle shaft, said throttle plate having at least one orifice, and at least one hinged flap located on said throttle plate for covering said orifice thereby controlling the flow area.
2. An arrangement for controlling idle speed of an engine, the arrangement comprising, An air intake system having an intake manifold, a throttle body assembly affixed to said intake manifold, said throttle body assembly includes a throttle plate attached to a throttle shaft, said throttle plate having at least one orifice, at least one hinged flap located on said throttle plate for covering said orifice thereby controlling the flow area, and a variable volume air bypass channel connecting the intake manifold on opposite sides of said throttle body for the bypass of air around throttle body.
3. The arrangement for controlling idle speed of an engine as claimed in either claim 1 or 2, wherein said flap can be rotated on a hinge to cover the orifice to reduce or increase flow area.
4. The arrangement for controlling idle speed of an engine as claimed in claim 2, wherein said air bypass channel having a valve to control the air flow.
5. The arrangement for controlling idle speed of an engine as claimed in claim 4, wherein said valve activated manually.

6. The arrangement for controlling idle speed of an engine as claimed in claim 4, wherein said valve activated by electromechanically.
7. The arrangement for controlling idle speed of an engine as claimed in claim 6, wherein said valve activated by an electronic controller based on engine speed.
8. The arrangement for controlling idle speed of an engine as claimed in claim 2, wherein said variable volume air bypass channel can be retrofitted on intake manifold using adaptors.
9. The arrangement for controlling idle speed of an engine substantially as herein described with reference to accompanying drawings.

ABSTRACT
"An Arrangement For Controlling Idle Speed Of An Engine"
Figure 1
This invention relates to a device that achieves control over engine idling speed for gas engines. The engine idle speed control mechanism consists of separate means for increasing and controlling the quantity of the mixture flow at idling. The throttle plate is provided with the bleed holes whose flow area can be varied. The external idle air bypass consists of a parallel path for gas air mixture flow under closed throttle condition. The idle speed controller may consist of one or more or a combination of these means. In order to have simplicity and reliability of operation with lower cost of the device, mechanical means of idle mixture control are proposed.

Documents:

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Patent Number

268787

Indian Patent Application Number

586/MUM/2008

PG Journal Number

38/2015

Publication Date

18-Sep-2015

Grant Date

16-Sep-2015

Date of Filing

24-Mar-2008

Name of Patentee

TATA MOTORS LIMITED

Applicant Address

BOMBAY HOUSE, 24,HOMI MODY STREET, HUTATMA CHOWK, MUMBAI.

Inventors:

#	Inventor's Name	Inventor's Address
1	DATTATRAYA RAJARAM KATKAR	BOMBAY HOUSE,24,HOMI MODY STREET,HUTATMA CHOWK,MUMBAI-400001.
2	DEEPAK SURYAKANT KULKARNI	BOMBAY HOUSE,24, HOMI MODY STREET,HUTATMA CHOWK,MUMBAI-400001.

PCT International Classification Number

F02D11/10

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA