FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
PROVISIONAL SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
BLOWBY GAS RECIRCULATION SYSTEM AND METHOD THEREOF


2. APPLICANT
MAHINDRA & MAHINDRA LTD.
1, GATEWAY BUILDING, APOLLO BUNDER, MUMBAI - 400001.
AN INDIAN COMPANY.
The following specification describes the invention.


FIELD OF THE INVENTION
The present invention generally relates to processing of blowby gas in an internal combustion engine in vehicle such as tractor or alike, and particularly, relates to a novel arrangement and method of recirculation of bloby gas to avoid evaporative emission, through simple and cost effective construction.
BACKGROUND OF THE INVENTION
In Internal combustion engine, at the end of combustion process, some amount of unburned or partially burned fuel-air mixture remains in the combustion chamber which escapes into the crankcase through the gap between the cylinder liner and the piston rings. This unburned or partially burned gas, also called as blowby gas, is highly concentrated with hydrocarbons and carbon particles. In past years, the practice was to discharge this blowby gas to atmosphere, but that meant causeing atmospheric pollution. To avoid this atmospheric pollution much work has been done in the field of crankcase blowby gas recirculation and emission control system towards a solution of routing this blowby gas back to the combustion chamber.
Blowby gas also consists of oil particles which are added to it due to flashing and evaporation of oil used for lubrication of engine components within the system. Hence an oil separator is provided in the path of blowby gas flow from crankcase to combustion chamber, so that oil gets separated and can be returned back to lubrication oil sump. Conventional practice in the field of tractors and similar farm

machines is to expose the blowby gas straight to atmosphere through a flexible blowby tube or pipe kind of arrangement connected to a cap placed on top of the cylinder head cover. When engine runs, blowby gas comes in the space between oil sump and crankcase, from there it goes up through crankcase to cylinder head then to cylinder head cover and is finally released to the atmosphere through blowby cap and tube arrangement. The blowby gas with some amount of lubricating oil vapor present therein results in environmental pollution.
Generally, the blowby gas coming out through blowby tube is distinctly visible as white smoke due to presence of unburned or partially burned fuel. This results in customer / user dissatisfaction as the white smoke is perceived as an indication of an unhealthy engine. To avoid this, many tractor manufacturers reroute the blowby gas tube in such a way that its open end comes near radiator fan, so that the white smoke (unburned fuel and oil) present in blowby gas is dispersed in the air draft of the radiator fan. Thus the problem is not solved but rather camouflaged so that customer / user cant notice the white smoke. However, the unburned fuel and lubricating oil vapour present in blowby gas sticks on to surrounding parts of the vehicle / tractor. Due to this, atmospheric dust, mud etc. sticks and gets accumulated onto these parts and in due course of time, the whole area turns sticky, black and dirty.
To avoid aforementioned problem, another solution has been provided by few tractor manufacturers, that is to connect outlet of blowby tube directly to intake manifold of the internal combustion engine. However, with this arrangement, the lubricating oil, soot & other abrasive contents of blowby gas directly enter into the combustion chamber

mixing with fresh filtered air coming from air cleaner. This arrangement has another disadvantage. When engine (RPM) is revved up, high intake air depression (vacuum) is created in the intake system, which is transferred to crankcase via this blowby tube. As a result atmospheric air is sucked into crankcase and oil sump through front oil seal of the engine. Dust particles present in atmospheric air damage oil seal leap, dust particles mix with engine lubricating oil and damage moving parts of the engine.
There are patents which describe different processing systems of blowby gas as well as recirculation of blowby gas to combustion chamber via intake manifold. Some of them are mentioned hereunder as prior art.
US patent 3177858A discloses Anti-Fouiing of Blowby Return System which describes a system for supplying an additive fluid to mix with the return stream of crankcase emission flowing to the air intake manifold. The supply means typically includes a container for additive liquid, a delivery duct having an inlet in the container, and a venturi of adequate capacity to pass the blowby gas, the venturi communicating with the delivery duct to draw additive fluid from the container to the venturi for mixing in atomized form with the blowby gas as it flows to the air intake system. However, this invention has shortcomings such as having to provide for, within the constrained space, an additional container for storing additive fuel, separate regulator to control proper mixing of additive fuel with air fuel mixture, change in air fuel ratio which would further lead to change in chemical property of air fuel mixture and, thereafter, further leading to change in combustion

process. This makes the engine less reliable and adversely affecting its performance.
US Patent 4681068 discloses Biowby gas processing arrangement for automotive internal combustion engines which describes recirculation of biowby gas to intake manifold. This invention includes a cylinder block having a chamber for collecting biowby gas and plurality of oil mist separating passages for separating the oil from biowby gas and an oil separator to remove the oil remains in the biowby gas after passing through the oil mist passages and a PCV valve. However, the invention has disadvantages of having a complex design of cylinder block and addition of external chamber for collecting the biowby gas and an oil separator which would increase the size of engine and would not be possible at times to accommodate / fit in the provided engine compartment size.
US Patent 5803025 discloses a biowby disposal system for disposing of oil and contaminants from a contaminant mixture of internal combustion engine; it includes an air-oil separator, a biowby pump, an exhaust system, and plurality of passages connecting the engine, the separator, the pump, and the exhaust system. Air oil separator separates large amount of oil from biowby gas mixture and takes back to crankcase chamber. The remainder of the mixture is sent to engine exhaust system by a biowby pump so as to make this as part of overall exhaust emission stream. Some disadvantages here are, by making the contaminant mixture as part of conventional practice of exhaust system using a pump, may lead to develop back pressure in the exhaust manifold and further, will cause the combustion process to become inefficient, thereby affecting total engine performance. Also,

this invention consists of multiple passage ways which need proper routing within the limited engine compartment space and also, additional component like the pump would require power, eating into available engine power or needing some additional power source.
Hence, it is necessary to propose a solution which can overcome the disadvantages of aforementioned prior art. According to the proposed invention, a blowby tube is connected from a breather cap provided on top of the cylinder head cover, to oil bath bowl of the air cleaner existing on a tractor. This ensures that crankcase and oil sump pressure is governed by head of oil level present in oil bath and not by the depression in air intake system and does not go down drastically as mentioned above. So, when engine is running, oil content present in the blowby gas gets condensed and deposited in the oil bath of the air cleaner while remaining blowby gas bubbles out of the oil bath and goes to engine combustion chamber through layers of filter elements such as wire-mesh, provided in the air cleaner.
OBJECTS OF THE INVENTION
The present invention overcomes the shortcomings associated with the background art and achieves other advantages not realized by the background art.
The main object of the invention is to provide a blowby gas recirculation system for vehicles with oil bath type air cleaner, with a simple and cost effective method and construction.

Another object of the invention is to provide a blowby gas recirculation system without need of any additional oil separator or breather chamber, and hence without disturbing the present position and arrangement of the engine components.
Yet another objective of the invention is to make use of the existing breather tube and air clearner for directing the blowby gas to the combustion chamber through the air cleaner.
Yet another objective of the invention is to reclaim and reuse engine lubricating oil vapour present in blowby gas; the oil mist present in the blowby gas cools and condenses in the oil bath at the bottom of the air cleaner, other contaminants present in the blowby gas also get filtered and deposited at the bottom of the air cleaner.
Yet another object of the invention is, by directing the blowby gas through air cleaner, the oil mist present in the blowby gas gets cooled and deposited in the oil sump of the air cleaner making an additional oil supply so that frequency of topping-up of oil to the air cleaner is reduced.
One or more of these and other objects are accomplished by providing blowby gas emission control system comprising an oil bath air cleaner, a blowby gas tube and a breather cap Wherein
one end of the said blowby gas tube is connected to cylinder head cover via a breather cap and another end of the tube is connected to bottom of the said oil bath air cleaner so that the oil content present in

the blowby gas gets cooled down and collected in the oil sump in the air cleaner and other contaminants are filtered out when they pass through multiple layers of wire mesh and paper element filters, then goes to combustion chamber mixing with fresh air.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the present invention, as well as the structure and operation of the present invention, is described here below in details with reference to the accompanying drawing.
FIG. 1 shows novel arrangement of blowby gas recirculating system according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to FIG.l, describes a blowby gas recirculating system comprising an internal combustion engine 1, conventionally, having a central portion called crankcase or cylinder block 6, bottom portion called oil sump 10, and upper portion called cylinder head 5. The oil sump 10 serves as a reservoir to carry engine lubricating oil. The

cylinder block 6 carries cylinder sleeves, pistons, piston rings, etc, (not shown) and hollow provisions for disposing other engine components. The cylinder head 5 is also provided with hollow provisions to dispose other, respective, engine components and for making path for inlet manifold and exhaust manifold, and provided with a cylinder head cover 4 over the top to restrict flow of lubrication oil / blowby gas outside the engine.
Generally, an air cleaner 11 is located near the engine 1 to receive fresh and filtered air from atmosphere to combustion chamber. In accordance with present invention and with reference to FIG. 1, bottom bowl 8 of the oil bath air cleaner 11, which carries the same engine lubrication oil as in oil sump 10, is provided with a port 12 at the extreme bottom thereof. Said port 12 is welded / brazed with a steel or other material pipe 9, opening of which projects upwards. The cylinder head cover 4 is provided with a port 13 at the top side thereof and further mounted a breather cap 3 thereto. Port 13 of the said breather cap is connected with one end of a flexible tube 2, hereinafter called as blowby tube, and other end is communicated with upward end of the said pipe 9. Said upward end of the steel pipe 9 is maintained at a particular level, functionally, above the oil level 7 contained in the bowl 8 so as to ensure that the oil present in the bowl 8 will not overflow while the blowby tube 2 is disconnected from the upward end of the pipe 9.
The aforementioned detailed construction, according to the present invention, explains the processing of blowby gas and its recirculation to combustion chamber as described below. When engine is running, the unburned or partially burned air fuel mixture, referred as blowby

10
gas, present in the combustion chamber (not shown) is getting escaped through the clearance between piston and cylinder liner, to the crankcase 6. The hot blowby gas contains unburned hydrocarbons, carbon particles and also carries some amount of oil mist present in the chamber and thereafter goes to cylinder head cover 4 through hollow paths, which are provided for disposing different engine components, present in the crankcase 6 as well as cylinder head 5, and further gets accumulated there. From the cylinder head cover 4, the said blowby gas passes through the blowby tube 2 and bubble out from the oil present in the bowl 8 at the bottom of the air cleaner 11, thereby the oil content present in the blowby gas getting condensed and deposited in the bowl. Said bubbled out blowby gas then mixes with the fresh air coming to the air cleaner from atmosphere and goes to combustion chamber through intake manifold.