US3056420A

US3056420A - Crankcase vent valve

Info

Publication number: US3056420A
Authority: US
Inventors: Howard H Dietrich
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1960-06-15
Filing date: 1960-06-15
Publication date: 1962-10-02
Anticipated expiration: 1979-10-02

Description

Oct. 2, 1962 H. H. DIETRICH CRANKCASE VENT VALVE Filed June 15, 1960 2' -1 u ..1 LL

LLI U) 0 2 [I U I I I l I I8 15 I2 9 INVENYZOR.

MANIFOLD VACUUM Zdarafiflze/rzcfi ATTORNEY United States Patent Ofiice 3,056,420 Patented Oct. 2, 1962 3,056,420 CRANKtZASE VENT VALVE Howard H. Dietrich, Rochester, N.Y., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed June 15, 1968, Ser. No. 36,240 5 Claims. (Cl. 137-245) The present invention relates to a valve device for venting or drawing off fuel vapors from an internal combustion engine crankcase and redirecting them into the intake manifold whereby they will subsequently be consumed during the combination cycle of the engine. Valves of this type are generally old and function to draw off such fuel vapors in accordance with variations in manifold vacuum. More specifically, the present invention relates to an improved crankcase vent valve in which a non-clogging feature has been added.

Crankcase ventilating valves of the general type involved are important as means for eliminating one source of unburned fuels which have been vented to the atmosphere in the past. The present vent valve insures the consumption of crankcase gases by the engine and avoids their being discharged into the atmosphere.

The details as well as other objects and advantages of the present invention will be apparent from a perusal of the detailed description which follows.

In the drawings:

FIGURE 1 is a diagrammatic representation of the subject vent valve cooperating with an internal combustion engine; and

FIGURE 2 is a graph showing the general relationship of crankcase air flow to manifold vacuum.

Referring to FIGURE 1, an internal combustion engine is shown generally at including a carburetor 12 mounted on an intake manifold 14, a crankcase 15 and an oil pan 16. During normal engine operation a certain amount of the combustion gases are blown by the engine cylinder piston rings into the crankcase. In the past, crankcases have been openly vented, usually through the crankcase filler pipe, whereby the blow-by gases have been discharged to the atmosphere and thereby contributing to the contamination of the latter.

In the present invention, a vent valve device 18 is provided whereby crankcase gases are adapted to be drawn into intake maniiold 14 and subsequently consumed during the normal combustion cycle of the engine. Vent valve device 18 includes a pair of easing

members

20 and 22 peripherally clamping a diaphragm 24 therebetween. In the present instance, diaphragm 24 is made of metal and actually provides a spring force the purpose of which will subsequently be considered. To permit adequate fiex ing a plurality of concentric annular rings or folds 26 are formed in diaphragm 24.

A central opening is provided in casing 20 and adapted to threadably receive a tube 28 which is open at one end and communicates at its other end through a conduit 30 with crankcase 15. The open end of tube 28 terminates adjacent the flattened center portion 32 of diaphragm 24. The spring construction of diaphragm 24 is such that it is urged away from the open end of tube 28 thereby tending to communicate chamber 34 defined by diaphragm 24 and casing 20 with the tube. A second tube 36 extends through a second opening provided in casing 20. Tube 36 communicates with intake manifold 14 through a conduit 37. Thus both tubes 28 and 36 are adapted to communicate with chamber 34 and thereby cause air to flow from crankcase 15 to intake manifold 14.

A central opening is provided in casing 22 and is adapted to threadably receive an adjusting screw 38. Adjusting screw 38 provides a seat for one end of a spring 40 the other end of which biases against central portion 32 of diaphragm 24. By adjusting screw 38, the resultant spring actuation of the metal diaphragm 24 may be varied to vary crankcase air flow. A second hole 42 is provided in casing 22 and communicates chamber 44 defined by casing 22 and diaphragm 24 to the atmosphere.

Upon a decrease in manifold vacuum the spring force of diaphragm 24 will uncover the open end of tube 28 permitting manifold vacuum to draw crankcase gases through the open end of tube 28 and out of tube 36 to intake manifold 14. On the other hand, during conditions of high manifold vacuum, as occurs during light engine loads, the vacuum force acting on the right side of diaphragm 24 will move center portion 32 of the diaphragm to block the open end of tube 28. However, to insure a predetermined amount of crankcase ventilation even under high vacuum conditions, a slot 46 is formed in tube 28 which provides a desired low value of crankcase venting since blow-by is low at light engine load and little air flow is required. Also at idle total air flow into the engine is low, e.g., 6 c.f.m. most of which should go through the carburetor for proper i-dle operation of engine.

Referring to FIGURE 2, a curve is indicated showing the relationship between crankcase air flow and manifold vacuum. The curve indicates a relatively flat portion A representing the constant air flow condition which occurs when diaphragm 24 closes the open end of tube 28. Under this condition crankcase air flow is limited to that amount which passes through slot 46. Portion B of the curve illustrates that as manifold depression decreases diaphragm 24 progressively uncovers the open end of tube 28 thereby increasing the quantity of air flow through the crankcase.

The present device insures the minimum air flow represented by portion A of the curve of FIGURE 2 even when manifold vacuum is suificiently high to block the open end of tube 28.

Inasmuch as crankcase gases contain particles of oil and other impurities, over a period of time slot or fixed orifice 46 can become clogged thereby reducing or entirely eliminating crankcase air flow under the high manifold vacuum conditions noted. To prevent this occurrence a hairpin like spring wire 48 is provided. One end of wire 48 is fixed to tube 28 while the other end is free and biases against central portion 32 of diaphragm 24. Thus as diaphragm 24 flexes, wire 48 is moved longitudinally back and forth through slot 46 thereby continuously cleaning the same and leaving it free of any fouling material. The spring force of wire 48 is negligible and is not intended to in any way affect the spring function of diaphragm 24.

I claim:

1. An engine crankcase vent valve comprising first and second casing members, a resilient diaphragm peripherally clamped between said casing members, a first tube centrally supported by one of said casing members and terminating in an open end disposed proximate said diaphragm, a vacuum chamber defined by said diaphragm and said one casing member, a second tube mounted in said one casing member and openly communicating with said chamber, said first tube having an engine crankcase connection, said second tube having an engine intake manifold connection whereby when said engine crankcase connection is made to an engine crankcase and said intake manifold connection is made to an engine intake manifold crankcase gases may be drawn through said first tube, said chamber and said second tube to be discharged into an engine intake manifold said diaphragm being adapted to be moved under the influence of engine manifold vacuum to block the open end of said first tube against the resilient force of said diaphragm, a slot formed in said first tube and openly communicating with said chamber under all operating conditions, and means operated by said diaphragm to clear said slot of any impurities tending to collect therein.

2. A crankcase vent valve as set forth in claim 1 which includes means for adjusting the resilience of said diaphragm.

3. A crankcase vent valve as set forth in claim 1 in which said slot cleaning means includes a hairpin like wire member fixed at one end to said first tube and having its other end projecting through said slot and engaging said diaphragm whereby movement of the diaphragm will cause said other end to move through said slot.

4. A crankcase vent valve as set forth in claim 2 in which the means for adjusting the diaphragm comprises a screw member threadably supported in the other of said casing members and a spring member biasing between said adjustable screw and said diaphragm.

5. A crankcase vent valve as set forth in claim 1 in which said resilient diaphragm comprises a thin metallic member having a flat central portion and a plurality of concentrically related annular folds.

References Cited in the file of this patent UNITED STATES PATENTS 10 2,592,380 Beckett Apr. 8, 1952 2,716,398 McMullen Aug. 30, 1955 2,742,057 Krieck Apr. 17, 1956 2,884,950 Settelmayer et 'al May 5, 1959 l I I l