FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL SPECIFICATION
(See Section 10; rule 13)


TITLE OF THE INVENTION A Novel Reed Valve Controlled Exhaust Gas Recirculation (EGR) System
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. Dattfltraya R. Katkar, Mr. Deepak S. Kulkarni and Mr. N B
Khandarkar all 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 refers to exhaust gas recirculation for an internal combustion engines. More particularly, it deals with the mechanical controls on EGR to suit engine requirements
BACKGROUND OF INVENTION
Environmental concerns and fuel economy are becoming major concerns world over. Exhaust gas recirculation has emerged as a technology to achieve these goals in cost effective way. Different EGR mechanisms are developed to suit different engine requirement. These include On - Off EGR, proportional EGR etc. In modern engines the EGR flow is controlled by the engine management system. All these systems make use of electronic and costly equipment to control the EGR to meet the engine requirement. The engine requirement for EGR is as below -
i) No EGR at idle
ii) Proportionate EGR flow under mid speed and load
iii) No EGR at full load If these requirements are met with a simple and low cost system the system can be implemented on low end engines as well. The present invention aims at providing a mechanical EGR control system for automotive engines.
PRIOR ART:
US patent no 5241940 teaches about exhaust gas recirculation system contains pressure sensors responsive to changes in exhaust manifold gas pressure to control the movement of EGR. A water vapor condenser is installed in the exhaust gas signal line to the pressure sensor so that any water vapor present in the exhaust gas will be condensed out and not cause a malfunction of pressure sensor and erroneous output signal.
US patent 6062 535 teaches about a flow control valve having a controllable flow area which varies with the valve displacement. The flow control valve includes a

poppet - type valve element mounted to reciprocate between a closed and open position in a valve cavity formed in valve housing. The valve housing has an inlet and outlet passage to allow the fluid to flow there through. A removable insert having a flow passage is positioned in the valve cavity adjacent the poppet valve for controlling the flow rate of gaseous fluid from the inlet passage to the outlet passage while the poppet valve is in an open position. Movement of the poppet valve from a closed to an open position varies the effective cross sectional flow area of the flow passage.
US patent no 5,937,834 teaches about exhaust gas recirculation apparatus capable of preventing the occurrence of dewing inside an exhaust gas recirculation pipe after the engine stop and corrosion inside the exhaust gas recirculation pipe. An EGR valve, a reed valve etc., and eventually capable of improving the engine durability and engine life. The exhaust gas recirculation apparatus includes an exhaust gas recirculation pipe having an EGR valve for controlling an exhaust recirculation quantity and connected between an exhaust passage includes an exhaust gas recirculation pipe having an EGR valve for controlling exhaust recirculation quantity and connected between an exhaust passage and an intake passage in an internal combustion engine equipped with a supercharger, and a check valve for preventing intake air from flowing into the exhaust gas recirculation pipe when an internal pressure of exhaust gas recirculation pipe is lower than an internal pressure of intake passage, disposed at the junction between exhaust gas recirculation pipe and the intake passage, wherein the check valve has a clearance for communication between exhaust gas recirculation pipe and the intake passage while the engine stops.
US patent no 4475 525 teaches about exhaust gas recirculation system for an internal combustion engine, orifices disposed in a passage for reticulating the exhaust gas made of a sheet of a bimetal or other material capable of changing from a normal shape to deformed shape when the heat of exhaust gas is applied in order to prevent carbon contained in exhaust gas from depositing on the orifices.

OBJECT OF INVENTION
• The main object of this invention is to provide a simple mechanism to EGR system.
• Yet another object of this invention is to provide the mechanical ON OFF switch to EGR system.
• Yet another object of this invention is to provide the mechanical ON OFF switch with independently settable On & OFF settings.
• Yet another object of this invention is to provide a robust mechanical ON OFF switch for EGR controls
• Yet another object of this invention is to provide a simple and cost effective ON OFF switch for EGR
SUMMARY OF INVENTION
The present invention aims at providing a ON /OFF as well as proportional characteristics for a mechanical EGR device. It primarily aims at providing mechanical reed valve strip for operation of ON OFF functionality. Two different plates are used for opening & closing EGR flow. The reed valve plates are attached to both the end of a tube in such a way that EGR off reed plate is placed upstream & EGR ON plate is placed to downstream side. The stiffness of the reed plates are selected according to set points for ON & OFF operations. Exhaust back pressure is used as an input signal for reed plate operation. The ON OFF arrangement can be add on type or it is integrated in the EGR circuit.
DESCRIPTION OF PREFFERED EMBODIMENTS
Fig. 1 shows EGR circuit for an internal combustion engine.
Fig. 2 shows EGR circuit for an IC engine in accordance with present invention.
Fig. 3 shows the details of EGR circuit for mechanical ON OFF system
Fig. 4 shows the details of the EGR circuit in accordance with spring loaded valve

As shown in Fig.l the EGR circuit for an internal combustion engine which is vaccum operated and comprises of an EGR tube (1) connected from exhaust (2) to intake manifold (3). The rate of exhaust flow is decided by the orifice diameter of tube (1). which is minimum flow area in the circuit.
As shown in Fig.2 the EGR system comprises of a tube (6) whose area is decided by the quantity of EGR flow required. The tube has two reed plates attached to both ends of tube. The reed tube upstream side of the tube is termed as OFF reed plate (7) and the plate downstream of the tube is termed as ON reed plate (5) During engine idle and under light loads ON reed plate is closed condition and thus during idle or at light loads there is no EGR flow into the engine. As the load on the engine increases the exhaust flow & exhaust backpressure increases the EGR On reed plate (5) is moved away from the opening hole of tube (6) and the EGR flow starts. As the engine speed increases in turn the backpressure also increases the ON reed plate move and in turn EGR flow increases further. Finally a steady state is reached when the engine load increases further the OFF reed plate is pushed towards the tube and thus closing the EGR flow into the engine. The stiffness of the reed valve plates are designed in such a way that the OFF reed plate is stiffer than ON plate. This ensures that the ON reed plate opens earlier and controls the EGR flow under part load operations and finally under high load operation the EGR is closed completely.
Fig.3 shows yet another configuration of EGR circuit suited for an internal combustion engine. As shown in fig.3 the circuit comprises of a mechanically operated ON OFF reed valve EGR system that comprises a through hole through which EGR is passed. Two reed plates are attached to both ends of the through hole. The reed plate upstream of the EGR hole is OFF EGR plate & the reed plate on downstream side of the EGR hole is ON EGR plate. The stiffness of reed plates are decided based on ON OFF points as a function of exhaust backpressure. The ON reed plate (8) is normally in closed position. As the engine operates at the idle

& light loads the ON reed plate does not deflected (open).As the load on the engines increases further the ON reed plate reflects in proportion to the backpressure thus EGR flow is regulated. As the engine load increases further the EGR ON reed plate open full and beyond a certain engine load near full load operation the EGR OFF reed plate (9) closes the EGR hole and stops the EGR flow completely.
Fig.4 shows yet another configuration of EGR flow regulating circuit suited for an internal combustion engines. The EGR circuit comprises of an EGR tube which connects exhausts manifold to inlet manifold. As ON OFF valve is placed with EGR circuit. The EGR valve is operated based on engine speed & throttle position signal. The further control & EGR is achieved by reed valve (10) or by spring loaded cone shaped spool valve(ll). The EGR flow is closed by closing the EGR valve.
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.
Dated this 26th day of March 2009
TATA MOTORS LIMITED
By their Agent & Attorney

Karuna Goleria of DePENNING & DePENNING