Okankcase ventilating system
US 2060883 A
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Description (OCR text may contain errors)
Nov. 17, 1936. w. w. LOWTHER 2,060,883
' CHANKCASE VENTILATING SYSTEM Filed July 15, 19.55
L K Fig.2
mus/v70? Wilfred W. Lowther 5v H/S AT7'0PNEY$ Patented New 3?, 393$ (CRANKCASE VENTILATING SYSTEM Application July 15, 1935, Seriai No. 311,379
8 Claims. (01. 123--1ll9) My present invention relates to internal combustion engines and more particularly to improved means for venting'and ventilating the crank cases of such engines. It is well known 5 that blow-by gases, to wit: gases blown 'by an engine's pistons from-the combustion chambers thereof into the crank case contain (a) unburned fuel vapors; and (b) water vapors with which such gases are heavily laden or nearly saturated.
These blow-by gases will, of course, if permitted to linger in and cool to the fdew point in the crank case, deposit fuel and water in the crank case which will become mixed with the engine's lubricant and present serious hazards to the enlo sine, which hazards are so well known as to need no enlargement.
It is an object of the present invention to positively prevent, under all engine-operating condi tions, the condensation of blow-by gases in crank 20 cases of internal combustion engines. In accordance with the'present invention, blow-by gases are rapidly withdrawn from the crank case under all operating conditions, and throughout the lower and most used engine speeds, a rapid circula- 5 tlon of clean air through the crank case is maintained. Condensation of blow-by gases in the crank case of an engine is, of course, most likely when the engine is cold since at this time combustion is poorest and thecool state of the crank 30 case causes rapid cooling to the dew point temperature or the heavily laden blow-by gases.
Engines are usually run in the lower speed ranges during the initial warming up period when conditions producing condensation of blow-by 35 gases in the crank case are greatest, and when this invention is employed, the blow-by gases of an engine operating in the lower speed ranges are immediately mixed with and diluted by fresh cold atmospheric air which, being essentially rel- 40 atively dry due to its cold state before entering the crank case, has its amnity for vapor materially increased when it is warmed up within the crank case, so that the dew point of the diluted blow-by gases is lowered to the point where it 45 will hold its vapors until removed from the crank case. In the high speed range, such as encountered usually only'after the engine has been warmed up to the point where condensation is less rapid, the blow-by gases are withdrawn with sufficient rapidity to prevent condensation thereof in the crank case. In the preferred arrangement,
only thoroughly cleaned air is circulated through the crank case. as In the drawing which illustrates said invention,
like characters indicate like parts throughout the several views.
Referring to the drawing:
Fig. 1 is a side elevation with some parts broken away and some parts shown in vertical sec- 5 tion, showing the invention applied to an engine which, for illustrative purposes, is a Ford V 8 engine; and
Fig. 2 is an enlarged axial section showing the air cleaner which is connected to the intake mani- 10 fold of the engine, and which by pipes or conduits, is connected to the crank case of the englue.
The construction and operation of a Ford engine such as now commercially and extensively sold byv the Ford company in connection with automobiles and trucks, is well known to those familiar with the art, and hence the parts thereof may be briefly noted as follows:
The cylinder block of the engine, which, as is well known, includes angularly disposed sections, each containing a bank of four cylinders 3, is indicated as an entirety by 3. The crank shaft is indicated as an entirety by 4 and the crank case, which latter serves as an oil reservoir, is indicated by 4'. The carburetor indicated by 5 and which is of the well-known double Venturi tube type, is provided with a throttle valve 5','for each Venturi tube thereof. The carburetor is connected to the engine cylinders through an integrally formed pair of intake manifolds'fi and ii, each of which manifolds extends from an opposite throttle valve controlled Venturi tube and distributes explosive mixture to an opposite bank of c linders 3. The manifolds t and 6" of theFord V 8 engine, are integrally formed in a plate i that extends between opposite block sections and serves to close the intermediate upper portion of the crank case i. 'In carrying out the invention, the oil filler tube 1' of the crank case, which is normally open 40 to the atmosphere, is sealed by a screw-threaded cap or the like 8. The carburetor 5 is supplied with gasoline from the supply tank, not shown, through a feed; line it having interposed therein the customary fuel pump II. This fuel pump is operated from the engines cam shaft 9 through connections, not shown, but which extend through a bearing sleeve l I and the base portion I t" of the fuel pump, which base, it will be noted, is open to the crank case.
In carrying out the invention, the intake of the engine is preferably provided with an air cleaner for removing all impurities from the air before delivery to the engine, but in so far as the in- 55 vention is concerned, this air cleaner may take various different forms.
The air cleaner illustrated comprises an axial clean air delivery or discharge tube l2, a dome or cover l3, a depending skirt or cylindrical case section I4, and a bottom-forming plate [5 provided with an upstanding cylindrical or annular flange l6 that is spaced from the skirt H so as to afford an annular air intake tube H. The bottom plate IS, with its upstanding flange l6, affords an oil well l8 in the bottom of the casing. On the bottom plate I 5 is an upstanding annular flange I9 that affords an annular oil cup within the well. The annular space surrounding the clean air discharge tube I2 is filled in with an oil and dust-intercepting means 20, preferably made up of screens. This screen is therefore placed in the air passage between the oil well and the clean air outlet of the air cleaner. The oil well will contain oil at a suitable level, usually in the vicinity of the top of the flange l9 when the air cleaner is idle. The dome I3 is shown as connected by a nut-equipped stud 2| to a cross bar 22a secured within the air tube l2.
In the arrangement illustrated, the clean air discharge tube l2 of the air cleaner is telescoped over and connected by a clamping band 23a or other suitable means to the upper end of the upstanding air intake neck or tube 9a of the carburetor 5.
In accordance with the invention, venting of the crank case and circulation of the air therethrough is brought about by independent connection of points of the engines intake at opposite sides of the throttle valves 5' to the crank case at points above the maximum oil level therein. Since it is desired to circulate only clean air through the crank case, the connections above noted are preferably taken from the intake on the engine side of the air cleaner.
In the preferred application of the invention to the Ford V 8 engine, and as illustrated, a conduit 22 is run from the atmosphere side of the throttle valve-equipped carburetor to the upper rear end portion of the crank case 4, and conduits 23 are provided for connecting the front top portion of the crank case to the intake at the engine side of the throttle valve-equipped carburetor. The conduit 22 is coupled to the intake neck 9a of the carburetor and opens into the base ll" of the fuel pump H so as to communicate with the crank case through the base of the fuel pump and the filler neck 1'. The'conduits 23 are in the nature of small holes drilled in the front end portions of the intake manifolds 6 and 6'. With the connections thus made, the conduits 22 and 23 will both be subject to vacuum or sub-atmospheric pressure under all operating conditions, but the conduits 23 will be subject to greater vacuum or more greatly reduced pressure than the conduit 22 by virtue of the air restriction offered by the throttle valve-equipped carburetor. This restriction set up by the carburetor, while always existent to some extent, will be at maximum when the throttle valve is closed and will be at a minimum when the throttle valve is open.
When the engine is operating at idle or slow speed, the throttle valve 5' being now closed, will greatly restrict the intake and the resultant difference in vacuum or pressure between points of connection of conduits 22 and 23 to the intake will be so greatly in favor of conduits 23 that the crank case will be maintained under greater vacuum or lower sub-atmospheric pressure than that existent in conduit 22, and this in spite of luted with clean cold air now rapidly circulated through the crank case. This dilution of the gases with clean cold air raises the dew point temperature of the mixture to a point where it will'easily hold its fuel and water vapors during its brief stay in the crank case. In practice, it has been found practically impossible to remove undiluted blow-by gases from a very cold crank case with suflicient rapidity to prevent condensation when the moisture-laden gases contact the cold metal parts, but by immediately diluting gases and then rapidly removing the same, as above outlined, condensation is prevented under very severe conditions.
The condition above recited will continue to a varying extent throughout the most used engine speed range, although the difference between crank case pressure and the pressure. in the intake at the point of connection of conduit 22 will be reduced as the speed of the engine is increased, such reduction being due to the following factors, to wit: (a) the reduction in intake vacuum or pressure differential between points of connection of conduits 22 and 23 to the intake, by virtue of reduced intake restriction under increased opening of the throttle valve; and (b) the inevitable increase in the volume of gases blown into the crank case under increased engine speed. At some point, usually quite high in the speed range and variable according to the crosssectional areas and relative cross-sectional areas of conduits 22 and 23 and the condition of the engine, the sub-atmospheric pressure in the crank case will rise slightly above that of the intake at point of connection of conduit 22 thereto, although still remaining below that of conduits 23. At this point, the circulation of engine intake air through the crank case will cease, the movement of air through conduits 22 reversing and now being from the crank case to the intake. From this point upward to maximum engine speed, conduits 23 and 22 will function jointly and collectively in withdrawing of blow-by gases from the. crank case and through their joint operation, will retain the crank case pressure well within safe limits and usually much below that prevailing under like conditions in crank cases vented'by the conventional open breather tube. Since, as before stated, engines are seldom run in the high speed range when very cold, condensation will be prevented by this rapid removal of the gases without dilution by fresh cold air.
In accordance with the preferred arrangement illustrated, it is important to note that the conduits 23, which carry all of the blow-by gases to the intake at the lower speeds, at which time condensation is most apt to occur, are entirely within the engine enclosure and are exceedingly short. These short internally located conduits 23 carry the moisture-laden gases to the intake without permitting the same to cool to a "dew point temperature, whereas longer external connections would be apt to chill the gases to the dew point.
The invention herein described has been thoroughly tested on a large number of cars and under many different and widely varying conditions, and has proven highly efiicient for the purpose stated. Not only does the system described efficiently eliminate condensation of gases therein, but also functions efliciently to prevent condensation of gases in the base portion of the fuel pump.
What I claim is:
1. The combination with an internal combustion engine having a sealed crank case, and an intake provided with a throttle valve therein, oi a crank case ventilating system comprising conduits extending from the intake at opposite sides of the throttle valve and independently opening into the crank case at points above the oil level in the crank case.
2. The structure defined in claim '1 in further combination with an air cleaner connected in the intake at the atmosphere side of the said throttle valve and crank case connecting conduits.
3. The combination with an internal combustion engine having a sealed crank case, and an intake provided with a carburetor therein, of a crank case ventilating system comprising conduits extending from the intake at opposite sides of the carburetor'and independently opening into the crank case at points above the oil level in the crank case.
4. The structure defined in claim 3 in further combination with an air cleaner connected in the intake at the atmosphere side of the said carburetor and crank case connecting conduits.
5. The combination with an internal combustion engine having a sealed crank-case, and an intake provided with a throttle valve-equipped carburetor, of a crank-case ventilating system comprising conduits extending from the intake at opposite sides of the carburetor throttle valve and independently opening into the crank-case at points above the oil level in the crank-case.
6. The combination with an internal combustion engine having a sealed crank-case, and an intake provided with a throttle valve-equipped carburetor, of a crank-case ventilating system comprising conduits extending from the intake at opposite sides of the throttle valve-equipped carburetor and independently opening into the crank-case at points above the oil'levei in the crank-case.
7. The structure defined in claim 5 in further combination with an air cleaner connected in the intake at the atmosphere side of the throttle valve-equipped carburetor and crank-case connecting conduits.
8. The structure defined in claim 6 in further combination with an air cleaner connected in the intake at the atmosphere side of the throttle valve-equipped carburetor and crank-case connecting conduits.
WILF'RED W. LOWTHER.