Crankcase vacuum system

An engine crankcase vacuum system wherein a check valve is interposed between the intake manifold and the fuel pump and is in open communication with the crankcase breather of the engine in order to rapidly create and maintain a vacuum in the crankcase. The crankcase vacuum greatly reduces oil migration around the piston rings and valve guides of the engine in order to reduce oil consumption, decrease contamination of the combustion chamber from oil leakage, and reduce detonation tendency. The crankcase vacuum also allows a reduction in oil ring tension which in turn reduces engine friction, resulting in a high power output and cooler running engine during operation thereof.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to improvements in engines and more particularly, 
but not by way of limitation, to a crankcase vacuum system for improving 
the overall operation of the engine. 
2. Description of the Prior Art 
In an internal combustion engine, or the like, a crankcase is usually 
bolted or otherwise secured to the engine block for encasing the crank 
shaft and bearings and for maintaining a supply of suitable lubricating 
fluid or oil for operation of the pistons, and the like. During the 
operation of the engine, the lubricating fluid or oil frequently leaks 
across the piston rings and enters the combustion chamber, which not only 
fouls the combustion chamber but also reduces the operating efficiency of 
the engine. 
SUMMARY OF THE INVENTION 
The present invention contemplates a novel crankcase vacuum system which 
has been particularly designed for overcoming the foregoing disadvantages. 
The novel system comprises a check valve interposed between the fuel pump 
and intake manifold of the engine, and in communication with the crankcase 
breather. When the engine is started, the normal manifold vacuum quickly 
evacuates the crankcase through the check valve. The manifold vacuum will 
pull through the check valve at any time when the intake manifold vacuum 
is greater than the crankcase vacuum, and this condition is particularly 
present when the engine is at an idling speed or when the engine is at a 
part throttle operating condition. The fuel pump continuously draws a 
vacuum, particularly in these operating conditions, since it is driven by 
the engine. 
During higher throttle operation of the engine, and particularly at a wide 
open throttle operation, the manifold vacuum will drop below the crankcase 
vacuum. When this happens, the check valve will automatically close and 
prevent the communication of the manifold pressure to the crankcase. The 
fuel pump continues to draw a vacuum, and since the check valve is closed, 
this fuel pump operation maintains the crankcase vacuum. 
Of course, other means of producing a vacuum in the crankcase may be 
interposed in the system, either in series with or parallel with the 
manifold, crankcase and fuel pump. In any event, the creation of the 
vacuum in the crankcase provides an improved oil control, reduces oil 
consumption, maintains a cleaner condition for the combustion chamber, 
reduces detonation tendency, and allows a reduction of oil ring tension 
for reducing engine friction and increasing power output with a cooler 
running engine. The novel system is simple and efficient in operation and 
economical of installation.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings in detail, and particularly FIG. 1, a crankcase 
vacuum system is shown which comprises a suitable check valve 10 secured 
to a conduit or tube 12 extending to the intake manifold (not shown) of an 
internal combustion engine, or the like (not shown). Whereas the valve 10 
may be of any well known type, as shown herein, the valve comprises a 
housing 14 having an inlet port 16 provided at one end thereof and an 
outlet port 18 provided at the opposite end thereof. The inlet port 16 is 
preferably in communication with the interior of the conduit 12 and 
suitable sealing means 20 may be interposed between the inlet 16 and 
conduit 12 for precluding leakage of fluid therebetween. A closure member 
22 is movably disposed in the proximity of the outlet port 18 and is 
yieldable retained in engagement therewith in any suitable manner, such as 
by a helical spring 24 anchored between the closure member 22 and the 
inner periphery of the housing 14. The spring member 24 maintains the 
closure member 22 in a normal closed position against the outlet port 18 
as is well known. However, when the pressure differential acting on the 
closure member 22 exceeds the force of the spring 24, the closure member 
22 will be moved away from the port 18 for permitting the flow of fluid 
therethrough as will be hereinafter set forth. 
The outlet port 18 is in communication with a suitable conduit 26 which is 
connected with a line or conduit 28 by a suitable Tee-fitting 30, or the 
like, as is well known. The conduit 28 extends between the usual fuel pump 
32 and a line or conduit 34 communicating with the usual crankcase 
breather (not shown), and in this manner the check valve inlet port 22 is 
in communication with both the fuel pump 32 and the interior of the 
crankcase for a purpose as will be hereinafter set forth. The fuel pump 32 
is provided with an outlet 36 which is open to the atmosphere. 
When the engine (not shown) is initially started in the usual or well known 
manner, a vacuum is pulled or created in the intake manifold, and this 
vacuum is communicated to the valve 10 through the conduit 12 and the 
inlet port 16. When the vacuum in the intake manifold is greater than the 
vacuum present within the crankcase, or in other words, when the pressure 
within the intake manifold is less than the pressure within the crankcase, 
the pressure differential acting on the closure member 22 will overcome 
the force of the spring 24 and move the closure member away from the port 
18 whereby communication is established between the intake manifold and 
the interior of the crankcase. The crankcase will thus be quickly 
evacuated through the check valve to establish a vacuum in the crankcase. 
The reduced pressure thus present in the crankcase decreases oil migration 
around the piston rings (not shown) and valve guides, thus greatly 
reducing accidental passage of the lubricating fluids into the combustion 
chamber. 
Under any conditions wherein the vacuum present in the intake manifold is 
greater than the vacuum within the crankcase, the communication will be 
established between the manifold and crankcase through the valve 10. This 
condition is usually present at engine idling speeds, and at part throttle 
conditions. 
When the intake manifold vacuum drops to a point below the crankcase 
vacuum, the closure member 22 will be urged in a direction toward the port 
18 and maintained in a closed position thereagainst by the spring 24. This 
precludes the communication of the manifold pressure to the crankcase, and 
maintains the crankcase vacuum condition since the fuel pump draws a 
vacuum during its entire operation and the crankcase is in communication 
with the fuel pump 32 through the conduits 28 and 34. 
Referring now to FIG. 2, a modified crankcase vacuum system is shown 
wherein a first check valve 40 generally similar to the valve 10 is 
interposed in a suitable conduit 42 which communicates between the intake 
manifold (not shown) and a closed circuit conduit 44. The conduit 44 
extends from the inlet port 46 of the fuel pump 32 to the outlet port 48 
thereof for circulation of fluid pressure as will be hereinafter set 
forth. A first branch line or conduit 50 is interposed in the circuit 44 
and extends into communication with the interior of the crankcase (not 
shown), and a second check valve 52 is interposed in the circuit 44 
outboard of the conduit 50 with respect to the fuel pump 32. A second 
branch conduit 54 is interposed in the circuit 44 and extends into 
communication with a third check valve 56 which in turn opens to a pitot 
tube 58 which empties into the usual exhaust collector 60. 
In this embodiment of the invention, fluid pressure is circulated through 
the fuel pump in a closed pathway through the conduit 44. However, as in 
the first embodiment, a vacuum is pulled in the intake manifold upon 
energization of the engine (not shown), which opens the valve 40 and pulls 
fluid pressure in the direction indicated by the arrow 62. This pulls a 
vacuum in the crankcase (not shown) through the conduit 50 in the 
direction indicated by the arrow 64. As long as the pressure within the 
manifold is less than the pressure in the crankcase, the valve 40 will 
remain open for pulling the vacuum through the conduit 50. Of course, the 
pressure being evacuated from the crankcase may be exhausted through the 
circuit 44 in the direction of either arrow 66 or 68. The pressure moving 
in the direction of the arrow 66 passes through the open valve 52 for 
movement through the open valve 56 to discharge through the pitot tube 58 
into the exhaust collector 60. Of course, the outlet 48 is also in 
communication with the valve 56 wherein exhaust from the fuel pump 32 may 
pass through the valve and into the pitot tube 58 for discharge through 
the exhaust collector 60. 
When pressure conditions in the pitot tube 58 and in the downstream side of 
the valve 52 exceed the pressure being evacuated from the crankcase, the 
valve will automatically close, thus assuring that the vacuum condition in 
the crankcase will be maintained throughout operation of the engine. The 
valve 56 will close only when the pressure in the pitot tube 58 exceeds 
the pressure at the outlet 48 of the pump. 
As hereinbefore set forth, the novel crankcase vacuum system improves oil 
control, reduces oil consumption, and facilitates maintenance of a clean 
operating condition in the combustion chamber. In addition, oil ring 
tension can be reduced, which reduces engine friction, resulting in a 
higher power output and a cooler running engine. Furthermore, with the 
addition of the exhaust in the vacuum system, the capacity of the 
crankcase vacuum system is boosted or increased, thus enabling the system 
to handle higher concentrations or amounts of piston ring "blow by", or 
fluid leakage. 
From the foregoing it will be apparent that the present invention provides 
a novel crankcase vacuum system wherein a vacuum is rapidly pulled or 
created within the crankcase upon initiation of engine operation, and 
maintained therein throughout the engine operation, thus reducing piston 
ring "blow by" or oil leakage around the piston rings which results in a 
cleaner condition for the combustion chamber and provides greater engine 
efficiency with less oil consumption. 
Whereas the present invention has been described in particularly relation 
to the drawings attached hereto, it should be understood that other and 
further modifications, apart from those shown or suggested herein may be 
made within the spirit and scope of this invention.