Breather device for an internal combustion engine

Field of the invention

The present invention relates to "Breather device for an internal combustion engine" and more particularly to an oil separator device provided to separate oil from the blow-by gases in an internal combustion engine.

Description of the prior art

In internal combustion engines, such as 4-stroke motorcycle engines, a small portion of exhaust gases those are present after ignition of the air/fuel mixture in a cylinder of the engine penetrates between the cylinder and the piston into the crankcase. The amount of such "blow-by" usually increases as the engine wears.

The blow-by gas results in an increase of pressure in the crankcase that needs to be reduced in order to reduce loss of power or torque of the engine and consequently the crankcase typically is ventilated. In order to reduce toxic emission of the engine it is usually not permissible to ventilate the crankcase directly to the environment. Crankcase ventilation therefore usually comprises a tube that is connected with one end to a portion of the crankcase and with the other end to an air-filter element of the engine.

However, usually an oil-vapour is also emitted from the crankcase together with the exhaust and the ejected oil vapour will contaminate and eventually block-up the air-filter element. If the air filter element is contaminated, oil will typically be emitted directly into the environment. Thus it leads to further oil losses and decrease in efficiency of the engine.

Hence the main objective of the present invention is to provide a breather device for an internal combustion engine that eliminates any residual oil from the crankcase, thus preventing oil losses and unintended envirorrmental release.

Brief description of the invention

The present invention relates to an oil separator device provided on the air filter unit to separate oil from the breather (blow by) gases in an internal combustion engine. As blow-by gas coming from engine crankcases enters into an oil separator chamber through an intake path, the oil separator baffle is designed such that blow by gas change its flow direction for a plurality of times. At the time the flow direction of the blow by gas is changed in the oil separator chamber, due to collision of blow by gas with the baffle wall several times, oil mist contained in the blow by gas changes to oil droplets and falls onto the bottom plate. Bottom plate is inclined so as to collect oil drops into a drain tube and gases alone come out of the separator chamber and mix with the intake air.

Brief description of the drawings

Figure 1 illustrates side view of a motorcycle

Figure 2 illustrates an engine according to the prior art

Figure 3 and 4 illustrates an air cleaner assembly along with a section cut across A-B according to the present invention

Detailed description of the invention

A selected illustrative embodiment of the present invention will be now described with respect to the accompanying figures 1,2,3 and 4. A motorcycle as illustrated in figure 1 comprises of a frame 101, front fork 102 attached to a pivot tube 103 of the vehicle frame 101, a front wheel 104 attached to these front forks 102, a handle bar 105 connected to the front forks 102, a fuel tank 106 attached so as to straddle an upper part of the vehicle frame 101, a seat 107 attached to the upper reapportion of the vehicle frame 101, an engine unit 200 attached to the lower front section of the vehicle frame 101, a swing arm 109 attached to a lower rear section of the vehicle frame 101, suspended by a rear shock absorber 110 from the vehicle frame 101 and a rear wheel 111 attached to a rear end of swing arm 109. The intake system of the engine (not shown in the figure) comprises of a carburettor, intake duct and an air cleaner. The exhaust system of the engine (not shown in the figure) comprises of exhaust pipe and a muffler. The motorcycle is also provided with a side cover 112 for covering a side section of the vehicle frame 101, a seat cover (not shown in the figure) for covering a rear section of the vehicle frame 101 below the seat 107, a front fender 113 for covering an upper part of the front wheel 104, and a rear fender 114 for covering an upper part of the rear wheel 111. The core part of the engine 200 as illustrated in figure 2 is the cylinder 201 with the piston 202 moving up and down inside the cylinder 201. Some of the key engine parts along with their functions are spark plug (nor shown in the figure) which supplies the spark which ignites the air/fuel mixture so that combustion could occur; valves 203 wherein the intake and exhaust valves open at the proper time to let in air and fuel to let out exhaust; a piston 202 which is a cylindrical piece of metal that moves up and down inside the cylinder 201; piston rings 204 that provide a sliding seal between the outer edge of the piston 202 and the inner edge of the cylinder 201; connecting rod 205 which connects the piston 202 to the crankshaft 206; crankshaft 206 which turns the piston's up and down motion into circular motion; a sump 207 which surrounds the crankshaft 206 and contains oil which collects in the bottom of the sump 207; etc. The said crankshaft drives a driven shaft (not shown in the figure).

The blow by gases from the crankcase is passed through the air filter unit that filters it and adds to the intake gases going into for combustion. An air cleaner assembly 300 comprises an air filter unit, an air intake pipe, air outlet pipe, drain pipe, breather pipe, et. al.

According to one of the embodiments, the present invention relates to an oil separator device provided on the air filter unit in an air cleaner assembly 300 to separate oil from the breather (blow by) gases in an internal combustion engine. Figure 4 illustrates a sectional view along A-B as indicated in figure 3. As blow-by gas coming from engine crankcases enters into an oil separator chamber 301 through an intake path 304, the oil separator baffle 303 is designed such that blow by gas change its flow direction for a plurality of times. At the time the flow direction of the blow by gas is changed in the oil separator chamber 301, due to collision of blow by gas with the baffle wall 303 several times, oil mist contained in the blow by gas changes to oil droplets and falls onto the bottom plate. Bottom plate is inclined so as to collect oil drops into a drain tube 302 and gases alone come out of the separator chamber 301 and mix with the intake air.

Moreover, the oil separator baffle is removable and is a separate piece. This separate piece makes the passage most optimum for oil separation and for manufacturability.
Although the subject matter has been described in considerable detail with reference to certain preferred embodiments thereof, other embodiments are possible. As such, the spirit and scope of the appended claims should not be limited to the description of the preferred embodiment contained therein.

Claims We claim:

1. A breather device for an internal combustion engine, the said device
comprising

an intake means for receiving air and lubricant molecules from crankcase;

a fluid flow path receiving air and lubrication oil mist from said intake means;

a drain means, in fluid communication with said fluid flow path for

receiving lubricant oil mist, wherein the said fluid flow path causes

change in flow direction by incorporating a circuitous path having several hair pin bends.

2. The breather device for an internal combustion engine as claimed in claim 1, wherein the said circuitous path is incorporated in an air filter assembly through a baffle.

3. The breather device for an internal combustion engine as claimed in claim 1, wherein the said breather device is an integral part of air filter assembly.