US3182647A - Flame arrestor for crankcase ventilating apparatus - Google Patents

Description

May 11, 1965 L. J. BINTZ 3,

FLAME ARRESTOR FOR CRANKCASE VENTILATING APPARATUS Filed Feb. 28, 1964 2 Sheets-Sheet 1 'IIIII '0- g 6 INVENTOR. i Lou/.9 c]- B/NTZ BY' 20 i M 5 1/9214/ United States Patent 3,182,647 FLAME ARRESTOR FOR CRANKCASE VENTILATKNG APPARATUS Louis J. Bintz, Placeute, Calif, assignor to News- Thermad'or Corporation, Los Angeles, Calif a corporation of California Filed Feb. 28, 1964, Ser. No. 348,217 17 Claims. (Cl. 123119) The present invention relates to air pollution control by ventilating blowby gases from internal combustion engine crankcases and returning these blowby gases to the air-fuel intake systems, and it relates particularly to a novel method and apparatus employed in connection with such crankcase ventilating systems for preventing damage which might otherwise occur to the engine due to backfiring in situations when thereis gasoline in the crankcase, and for preserving normal carburetor operation during cold start conditions when such crankcase ventilating systems tend to disrupt the normal fuel-air mixture required'for vehicle starting.

Control of exhaust emissions from automotive internal combustion engines has become a serious problem in urban areas because of the large quantities of smogforming and other harmful exhaust gas components, such as unburned or partially burned hydrocarbons and carbon monoxide, which are being dumped into the atmosphoto from the engines of automobiles, trucks and buses. These pollutants are discharged into the air through the exhaust system of the engine, and also as gases blown past the pistons in the cylinders and into the crankcase. These contaminantcontaining blowby gases are then discharged from the crankcase into the air through the oil fill cap or other crankcase vent tube, such as the road draft tube usually employed with automobile engines. Such blowby gases account for a substantial portion of the air pollutants from internal combustion engines.

Several systems are presently in use for controlling these blowby exhaust gases, the systems usually involving con duit means connecting the crankcase with the intake manifold to utilize the vacuum condition in the intake manifold to draw the blowby exhaust gases out of the crankcase and into the vehicle intake system, so that the combustibles in the blowby gases, which are the principal harmful ingredients, will again be subjected to the engine combustion cycle. A typical crankcase ventilating system of this general type will provide the conduit between the valve rocker arm cover, which is accessible at the top of the engine and which communicates with the crankcase, and the intake manifold, which is also readily accessible. Some valve means is normally employed in the conduit so as to restrict or control the volume of gas flow from the crankcase to the intake manifold, in an attempt to prevent the application of too much vacuum to the crankcase, which would tend to draw air in through the crankcase seals, and at the same time to prevent the introduction of so much air to the engine intake system from the crankcase as to disrupt carburetion.

One such internal combustion engine crankcase ventilating system which has been found satisfactory is disclosed in copending application Serial No. 321,556, filed November 5, 1963, entitled Apparatus for Ventilating Internal Combustion Engine Crankcase, which is a joint application of the present applicant and Kenneth E. Rawald. Said copending application Serial No. 321,556, employs a flow regulator valve in the conduit from the crankcase to the intake manifold which is responsive both to intake manifold vacuum and to the vacuum or pressure condition within the crankcase so as to meter the flow from the crankcase to the intake manifold generally "ice in accordance with the amount of the blowby gases which are accumulating in the crankcase under various engine operating conditions. Although the present invention may be employed in connection with any crankcase ventilating system of the type embodying a conduit from the crankcase to the engine intake manifold, I have shown and described the present invention in association with a system having a flow regulator valve of the type disclosed in said copending application Serial No. 321,556, because when the invention is used in combination with such system the conduit from the crankcase to the intake mani fold is properly apertured for substantially all operational conditions that are likely to be encountered.

There are several problems in connection with crankcase ventilating systems which it is the purpose of the. present invention to cure. One problem is that under certain engine. operating conditions, such as when cranking the engine during cold starts, raw gasoline or gasoline fumes are likely to accumulate in the crankcase, and if the engine should backfire, i.e. if the mixture should ignite in the intake manifold and carburetor, with the added crankcase ventilating conduit the backfire flame will pass through the conduit and a damaging explosion may occur in the crankcase. Another problem which it is a purpose of the invention to cure is that when the engine is being started, particularly in cold wheather, air is drawn into the intake manifold from the crankcase through the communicating conduit of the ventilating system, which breaks the vacuum in the manifold and disturbs the fuel-air mixture, thus making starting more diificult.

in view of these and other problems, it is an object of the present invention to provide a novel method and apparatus employed in connection with a crankcase ventilating system of the type providing communication between the crankcase and the engine intake manifold, which will positively block the passage of backfire flames from the intake manifold through the crankcase ventilating conduit so that any gasoline or gasoline fumes in the crankcase cannot be ignited by backfiring. I

Another object-of the present invention is to provide a method and apparatus of the characterdescribed for use in a crankcase ventilating system, wherein the ventilating conduit from the crankcase to the intake manifold is effectively closed during cold start conditions so that the intake fuel-air mixture will not be disturbed by air being sucked in from the crankcase, yet which does not interfere with the normal ventilating operation of the system under other engine operating conditions.

A more specific object of the present invention is to provide novel valve apparatus in a crankcase ventilating system which is normally open to permit the free flow of blowby exhaust gases from the crankcase to the intake manifold, yet which automatically closes in response to backfire pressure in the intake system to protect against crankcase explosions, and which will also automatically be held closed during cold start conditions to prevent disturbance of the normal fuel-air mixture at that time.

Further objects and advantages of the present invention will appear during the course of the following part of the specification, wherein the details of construction and mode of operation of several embodiments are described with reference to the accompanying drawings, inwhich:

FIGURE 1 is an elevation view showing crankcase ventilating apparatus embodying the present invention in a typical installation, with an associated internal combustion engine graphically represented in phantom.

FIGURE 2 is an axial section through the How regulator valve of the system shown in FIGURE 1, with one embodiment of the flame arrestor of the present invention disposed in the same case as the flow regulator, the

3 elements of the flow regulator and flame arrestor being shown in positions they would assume during engine operation.

FIGURE 3 is a cross-sectional view taken on the line 3-3 in FIGURE 2, illustrating internal details of construction'of the flame arrestor.

. FIGURE 4 is an exploded view illustrating the fire check plate and seal diaphragm components of the embodiment of the invention shown in FIGURES 2 and 3.

FIGURE 5 is an axial sectional view similar to FIG- URE 2, but with the elements of both the flow regulator and the flame arrestor shown in their positions of repose, as they would be with associated internal combustion engine inoperative.

FIGURE 6 is an axial section generally similar to FIGURE 2, but illustrating an alternative form of the flame arrestor associated with the flow regulator.

FIGURE 7 is a cross-sectional view taken on the line 7-7 of FIGURE 6 showing further details of this alternative form of the invention.

FIGURE 8 is an exploded view illustrating the spacer and valve element parts of the alternative form of the invention shown in FIGURES 6 and 7.

Referring to the drawings, and at first to FIGURE 1 thereof, the crankcase ventilating apparatus in which the present invention is employed is designated generally by the numeral 10, and includes a flow regulator 12 having an inlet conduit 14 which is connected to engine rocker arm cover 16. The blowby exhaust gases accumulating in the engine crankcase 18 flows through the engine along the path shown by the arrows to the space within rocker arm cover 16, and thence into conduit 14. The flow regulator valve 12 has an output conduit 20, in this case a flexible hose, which is connected to a suitable fitting on the intake manifold 22 of the engine. The flame arrestor 24- of the present invention has been shown embodied within an extension of the housing for the flow regulator valve 12, although it is to be understood that the fiame arrestor may be disposed at any place in the flow conduit means from the crankcase 18 to the intake manifold 22. Preferably, the flame arrestor will be disposed in the conduit means on the intake manifold side of the flow regulator valve 12 so as to provide protection for the flow regulator valve 12.

' FIGURES 2 to 5 illustrate the details of construction of the flow regulator valve 12 and the associated flame arrestor 24. Although the flame arrestor 24 may be employed in connection with any crankcase ventilating system which provides connection between the crankcase and the intake manifold, the particular system with which flame arrestor 24 has been shown in the drawings cooperates with the flame arrestor to provide substantially the desired rate of gas flow through the system under virtually all conditions of engine operation, which is unique for this combination of the particular flow regulator valve and flame arrestor shown.

Referring now particularly to FIGURES 2 to 5, the flow regulator valve 12 has a casing 26 which includes a body 28 and a cap 30 peripherally clamped to body 28. Formed as a part of the body 28 is a valve outlet nozzle 32 having an inner end opening 34 which provides the valve seat. A flexible diaphragm 36 is peripherally clamped between the body 28 and the cap 30 so as to divide the space within the casing 26 into a pair of chambers 37 and 38, the chamber 37 being on the body side of the diaphragm and the chamber 38 being on the cap side of the diaphragm.

A diaphragm plate 39 seats against diaphragm 36, and has a central bulge 40 which is adapted to seat in the nozzle opening 34 in the closed position of the flow regulator valve. The bulge 40 has a bleed slot 42 therein to permit a small amount of gas flow through the valve even in such closed position. Valve spring 44 is engaged at one end against the body 28, being positioned over valve o let nozzle 32, and is engaged at its other end against the diaphragm plate 39, the spring 44 holding plate 39 against diaphragm 36 and biasing the diaphragm and plate away from the nozzle opening 34 so that the position of repose of the valve is the open position. The spring 44 engages the diaphragm plate proximate the annular juncture between the bulge 40 and the fiat part of the plate, so that the spring 44 tends to center the bulge 40 with respect to the nozzle opening 34. Otherwise, the plate 39 is free-floatin g with respect to diaphragm 36, so that the plate bulge 40 has a self-centering action as it moves into the closed position in the nozzle opening 34. By this means, proper closure of the flow regulator valve is assured despite irregularities which might occur from manufacturing tolerances or some physical damage to the valve, thus assuring relatively accurate control of the exhaust gas flow through the valve.

The conduit 14 which is connected to the engine rocker arm cover communicates with valve chamber 37 through valve inlet port 46.

An atmosphere vent hole 48 is provided in cap 30 so that chamber 38 is an atmospheric pressure.

The spring 44 is a relatively light spring which is adapted to keep the valve nozzle open for outlet gas pressures (i.e. intake manifold negative pressures) equal to and more positive than a pie-selected outlet gas pressure. Thus, the spring has a force equal to the desired valve opening pressure times the effective diaphragm plate area opposite the valve nozzle opening 34.

The pre-selected pressure to be maintained at the regulator valve inlet port 46, and hence in the crankcase chamber itself, is a negative pressure sufficient to draw all of the blowby gases out of the crankcase, yet which is not so negative that too much air will be drawn in through the crankcase, or to cause a tendency to draw dirt in through the crankcase seals. While there is a sufficiently strong vacuum in the intake manifold to draw such blowby gases from the crankcase if a simple open tube connection is made from the manifold to the crankcase, such a procedure is not practical because the high manifold vacuums at low speeds are too high to be transmitted directly to the crankcase. The flow regulator valve 12 which is shown in FIGURES 2 and 5, and which has the same essential functional elements as that shown in said copending application Serial No. 321,556, provides controlled flow of gases from the crankcase to the intake manifold which closely matches the flow volume of blowby gases into the manifold.

The operation of the flow regulator 12 is generally as follows: The intake manifold vacuums are transmitted to the regulator valve through the valve nozzle 32 with its open end 34 inside the chamber 37, these negative pressures varying from about 20 inches of mercury to less than about 1 inch of mercury. These intake manifold negative pressures act directly upon the central bulge 4i) of the diaphragm plate, on an area about equal to the cross-sectional area of the nozzle opening 34, tending to pull the diaphragm and diaphragm plate against the open end of the valve nozzle to shut it. The spring 44 functions to push the diaphragm plate and diaphragm away from the open end of the valve nozzle when the blowby rate increases so that these gases may pass into the nozzle.

The spring 44 forces the diaphragm plate and diaphragm away from the valve opening when the intake manifold vacuum tending to close the valve becomes weaker than the force of the spring tending to open the valve. The spring is selected so as to have a valve opening force equal to the force of a selectedintake manifold negative pressure, as for example about 16 or 15 inches of mercury. The diaphragm will, therefore, be drawn against the open end of the valve nozzle at high manifold vacuums, as for example 20 to 16 inches of mercury. The blowby flow rate at these high manifold vacuums is low and the small amountof blowby gases are drawn into the valve nozzle opening through various leakage points, or by the limited access port formed by the bleed slot 42. When the intake manifold vacuums become weaker, or more positive, as for example 16 or inches negative pressure, the force of the spring pushes the diaphragm plate and diaphragm away from the valve nozzle opening allowing a larger gas passage to the valve nozzle. The blowby gas flow rate is beginning to increase at these manifold pressures, and gases are able to easily flow into the valve nozzle opening because of the larger access area. The now increasingly absolute, or more positive, pressures in the crankcase provided a lifting force against the diaphragm tending to push the diaphragm and diaphragm plate further away from the valve nozzle opening, making an even greater access passage.

There is always a negative pressure in the crankcase. At high intake manifold vacuums, the direct manifold action drawing the diaphragm plate and diaphragm down against the nozzle will be assisted by the weaker negative pressure in the crankcase, which will also tend to keep the valve shut by pulling on the larger area of the diaphragm which is radially outwardly disposed relative to the nozzle. However, as the intake manifold vacuum becomes weaker, the crankcase vacuumv likewise becomes weaker; and once the spring has opened the valve the crankcase vacuums will become increasingly weaker, tending to allow the spring to push the diaphragm even further away. In this regard, it is to be noted that the terms used herein stating that negative pressures or vacuums become weaker, or more absolute, or more positive, means that the pressure is approaching atmospheric pressure.

The crankcase pressures exert only a small diaphragm lifting pressure, but they exert their force on a much larger area of the diaphragm than the intake manifold pressures.

These crankcase pressures exert their force over an annular portion of the diaphragm extending from the diaphragm flexure or bending line into about the circular area of the bulge of the diaphragm plate adjacent the open end of the nozzle. The diaphragm'lifting action of the increasingly more absolute crankcase pressures on the larger area of the diaphragm increasingly releases the spring biasing force on the diaphragm plate and the spring pushes the diaphragm plate away from the valve nozzle providing a maximum size passage for unrestricted flow into the valve nozzle, and this condition is the condition of engine operation which provides high blowby flow rates.

As the engine speed or workload increases, the blowby flow rate will increase, and at the same time the intake manifold vacuum will decrease. Conversely, as the engine speed or workload decreases, the blowby flow rate decreases, while at the same time the intake manifold vacuum tends to increase. As seen from the above description of the operation of how regulator valve 12, the valve tends to be closed by increased manifold vacuums, and tends to be opened by increased flow rates of blowby gases into the crankcase, which tends to increase crankcase pressure, whereby the combined effects tend to modulate the valve so as to accommodate the flow of blowby gases at various engine operating conditions without applying too much vacuum to the crankcase, and without providing too much air from the crankcase to the intake manifold so as to interfere with proper carburetion.

FIGURE 2 illustrates the flow regulator valve 12 in a slightly open position, which would correspond to a moderate engine speed or workload, while FIGURE 5 illustrates the regulator valve in its completely open position, or position or repose, which is the position of the valve when the engine is not operating. It will be apparent that when the engine is being cranked for starting, at which time it is revolving at only about 50 to 150 r.p.m., the intake manifold vacuum will not be sufiicient to substantially close the valve 12, and it will be at or near its position of repose as shown in FEGURES, during which condition the how regulator valve 12 provides practical- 6 1y a wide open communication between the crankcase and the intake manifold. However, such wide open communication between the crankcase and intake manifold destroys the eifectiveness of the choke valve for cold start conditions, breaking the intake manifold vacuum, and provides added air so that the mixture is too lean for proper starting. Thus, it is important for proper cold starting to provide additional flow control means in the conduit from the crankcase to the intake manifold which will be substantially closed during cold start conditions to compensate for the substantially wide open condition of the how regulator valve 12, and this additional means is provided by the flame arrestor of the present invention.

Another circumstance in which it is important to close the conduit between the crankcase and the intake manifold is whenever there is a backfire (i.e. inadvertent ignition of the fuel-air mixture in the carburetor-intake manifold system). This latter circumstance is most dangerous whenever there is a tendency for raw gasoline or gasoline fumes to concentrate in the crankcase, which tends to occur during cold starting conditions and also frequently when the engine has been operating, is turned off, and is again turned on while it is still hot. The present invention automatically blocks the conduit between the crankcase and intake manifold whenever there is such a backfire, regardless of how open the regulator valve 12 might be at that particular engine operating condition.

The body 23 of the casing for the flow regulator valve is provided with an emension St) for housing the flame arrestor. Extension '54) has an annular shoulder 52, beyond which the extension terminates in an annular lip 54.

Seated against the shoulder 52 and disposed within lip '54 is a tire check plate 56, which may be composed of sheet metal or other suitable material, and which has a plurality of apertures 53 therethrough. -Although three of the apertures 58 can be employed, preferably there are four apertures 58 provided, and these are regularly spaced about plate 56 at approximately the same radial distance from the center of the plate. The =fire check plate 56 is preferably bowed or dished somewhat in the downstream direction for a purpose to be hereinafter described.

Immediately downstream of the fire check plate 56 is fire check seal diaphragm 69 comprising a relatively thin, flat sheet of materialwhich jis resilient and flexible and which has good memory characteristics, preferably but not necessarily an elastomer material; Diaphragm 6t has substantially the same diameter as the check plate'56, and is provided with a plurality of slits 62, the number of which depends upon the number ofapertures S8 in the fire check plate 56. Thus, in the embodiment shown in the drawings, a pair of the slits 62am provided, cross.- ing each other at right angles, with small circular holes 64 provided at the ends of the slits to prevent tearing. The slits 62 thus provide a plurality of generally .triangular flaps 66, these being four in number. in the embodiment shown in the drawings. The seal diaphragm 60 is rotationally oriented with respect to fire check plate 56 so that each of the flaps 66 registers with a respective aperture 58,.and the slits. 62 extend between the apertures 58. In this manner, when the sealdiaphragm 60 is in its position of repose, as shown in FIGURE 5, the flaps 66 will completely close oil the respective apertures 58. Since the seal diaphragm 69 is a fiat sheet of resilient material in its completely relaxed position, the bowed or dished shape of fire check plate so will apply a downstream deflection to each of the four flaps 66 of diaphragm d d as shown in FIGURE .5, which results in each of the flaps 66 being biased to its closedposition over its respective aperture 58 due to the resiliency of the diaphragm material.

The flame arrestor structure of the embodiment shown in FIGURES 2 to 5 is completed by a closure 68 which has an outwardly directed annular flange 7t) that fitsinto the body extension lip 54, the lip 5 3 being turned inwardly to compress the flange '76 against the periphery of diaphragm 60 so as to peripherally seal the diaphragm and fire check plate within the extension 50. Closure 68 also has a tubular nipple 72 which extends downstream and is adapted to provide a hose connection for the hose 20 shown in FIGURE 1 leading to the intake manifold. The closure 63 may also include a shoulder 73 facing upstream which limits the amount of flexing of the diaphragm flaps 66 to minimize wear of the flaps.

Under normal engine operating conditions the diaphragm flaps 66 are highly flexible, and they will not substantially impede the free flow of blowby gases passing from the crankcase and through the flow regulator valve 12 to the intake manifold. The flaps 66 will merely flex in a downstream direction as shown in FIGURE 2 so that the blowby exhaust gases will flow through the apertures 58 without substantial resistance from the flaps 66.

However, in the event of a backfire, there will be a sudden increase of intake manifold pressure with respect to the pressure in the crankcase, causing a reverse rush of gases, which will instantaneously close the flaps 66 over the respective apertures 58 and prevent the flame front of the backfire from passing through the flame arrestor 24, and hence back through the flow regulator valve 12 and into the crankcase, where raw gasoline or gasoline fumes might be ignited. At this time the fire check plate functions as a valve seat against which the diaphragm flaps rest. As the backfire subsides, and the normal direction of flow is resumed as indicated by the arrows in FIGURE 2, the flaps 66 will again automatically open.

Control of the flow of gases from the crankcase to the intake manifold during cold start conditions is achieved in the flame arrestor 24 by employing a resilient flexible material in the seal diaphragm 60 which becomes stilt or substantially rigid when it is cold, so that when the engine is cold the diaphragm flaps 66 will be fixed in their closed positions as shown in FIGURE 5, thus preventing any substantial flow of air or other gases from the crankcase to the intake manifold. It is desirable that the material of diaphragm 60 stiffen or freeze up at temperatures below about 70 F., and it is particularly important at sub-zero temperatures.

Although any sufliciently durable material having these characteristics may be employed in the present invention, one such material which the applicant has found to be satisfactory in operation is the synthetic rubber product Viton produced by Du Pont, which has the characteristic of stiffening and losing its flexibility at about 20 F. and lower, but which is quite flexible at higher temperatures.

When the engine is turned off after operation, it will be hot and the diaphragm 60 will be flexible, so that the diaphragm will automatically move to its closed position as shown in FIGURE 5. Thus, this is the position in which the diaphragm will stiffen when the engine becomes cold. Accordingly, when the engine is cold the diaphragm flaps 66 will remain substantially closed as shown in FIGURE and there will be no substantial flow of air or other gaseous materials from the crankcase into the intake manifold to in any way disturb the rather sensitive carburetion balance under cold starting conditions. However, long before the engine reaches normal operating temperatures of about 200 F. the diaphragm 60 will become highly flexible and the flaps 66 will be permitted to flex to their open positions as shown in FIGURE 2, to accommodate the passage of blowby exhaust gases from the crankcase to the intake manifold.

Referring now to FIGURES 6, 7 and 8, these FIG- URES illustrate an alternative flame arrestor 74 which utilizes a substantially rigid, spring-biased flame arrestor valve element instead of elastomcr seal diaphragm 60 of the form of the invention shown in FIGURES 2 to 5.

The flame arrestor 74 is adapted to be mounted in the flow regulator valve body extension 58, and includes a spacer 76 supported in the lip 54 against shoulder 52. Spacer 76 is in the form of a spider having radially outwardly projecting legs 78 which are engaged against the shoulder 52, and includes a central tubular guide ring 80 extending in the upstream direction from the legs 78.

The closure 82 is similar in construction to closure 68, including an outwardly directed annular flange 84 which seats against the spacer legs 78 and is secured there in substantially sealed relationship to the housing by the lip 54 of the housing extension being turned inwardly. The closure 82 includes nipple 86 to provide a connection for the hose 20 shown in FIGURE 1.

The flame arrestor 74 includes a valve element 35 comprising a generally flat disc 90 having peripheral tongues 92 which extend in the downstream direction at right angles to the disc. The flame arrestor valve element 88 is normally biased by a spring 94 toward its closed position against a valve seat $6 in the housing at the downstream end of nozzle 32. The spring 94 is engaged at one end about the tubular guide ring 86 and at its other end against the disc 90 of flame arrestor valve element 88, the valve element being held in alignment with the nozzle 32 by engagement of spring 94 between the tongues '52.

The spring 94 is a relatively light spring, so that the flame arrestor valve clement does not substantially impede the free flow of blowby exhaust gases from the crankcase to the intake manifold during normal engine operating conditions. However, in the event of a backfire, the reversed pressure differential will instantaneously move the flame arrestor valve element against the seat 96 to prevent passage of the flame front to the crankcase.

The flame arrestor embodiment '74 has a cold start operation which is somewhat similar to that of the embodiment 24 shown in FIGURES 2 to 5. Several factors contribute to this. One factor is that the engine starter will crank the engine at from about 50 to about r.p.n1., which produces only a relatively small amount of intake manifold vacuum. By choosing a spring 94 of the proper strength, the spring 94 will tend to hold valve element 88 in a substantially closed position when the engine is rotating at this very low starting speed, but as soon as the engine assumes a condition of normal operation, as for example idling (at 500 r.p. m. or more), or other operating condition, the pressure differential on opposite sides of the flame arrestor valve element 88 will cause the element 88 to open as shown in FIGURE 6.

Another factor contributing to the cold start operation of the flame arrestor embodiment 74 is the fact that a film of engine oil from the crankcase will become deposited on the flame arrestor valve element 88 and its valve seat 96, and when the engine is cold and flame arrestor valve element 88 is in its position of repose biased against its valve seat 96, the cold and hence viscous oil will cause the valve element 88 to stick against seat 96. This action is enhanced by providing flat surface engagement between the valve element disc 90 and the generally flat seat 96, which provides a substantial area of the viscous oil film for causing the valve element 83 to adhere to the valve seat 6. When the engine warms up, this oil will likewise warm up and become more fluid, thereby releasing the valve element 88 from seat 96.

While the instant invention has been shown and described herein in what are conceived to be the most practical and preferred embodiments, it is recognized that departures may be made therefrom within the scope of the invention, which is therefore not to be limited to the details disclosed herein, but is to be accorded the full scope of the claims.

What I claim is:

1. A flame arrestor for use in a crankcase ventilating conduit extending between the crankcase and the intake manifold of an internal combustion engine, said flame arrestor comprising a housing adapted to be disposed in said conduit, said housing having a passage therethrough forming a part of said conduit, a valve seat proximate said passage in said housing facing-downstream for the normal direction of gas flow from the crankcase to the intake manifold, a valve element in said housing on the downstream side of said seat, said valve element being held by the flow of gases in an open position spaced downstream of said valve seat during normal engine operation when the intake manifold is at a lower pressure than the crankcase to permit the substantially unimpeded flow of blowby exhaust gases from the crankcase through the conduit to the intake manifold, and the valve element being movable to a closed position against said seat to block the flame front from the crankcase upon a pressure reversal resulting from backfiring in the engine fuel intake system, and means lightly biasing said valve element toward said seat, whereby the position of repose of said element when the engine is inoperative and there is no pressure differential between'the crankcase and the intake manifold is the closed position of the element against the seat, said biasing means exerting a biasing force which is suiiiciently light so that during normal engine operation said element will not substantially impede the flow of blowby exhaust gases from the crankcase to the intake manifold.

' 2. A flame arrestor as defined in claim 1, wherein said biasing means has the physical characteristic that it stiflens and becomes substantially rigid at low temperatures corresponding to cold start engine temperatures, whereby under cold engine starting conditions said biasing means will be substantially rigid with said valve element in its said closed position so as to substantially block the flow of gases from the crankcase to the intake manifold so that such flow will not upset carburetion at that time.

3. Apparatus as defined in claim 1, wherein said valve element comprises a sheet of resilient material supported in said housing with a portion thereof movable between said open and closed positions, said sheet being so arranged that the resiliency thereof provides said biasing means.

4. Apparatus as defined in claim 1, wherein said valve element is a substantially rigid member, said biasing means comprising a spring supported in the housing and engaged against the valve element.

5. Apparatus as defined in claim 4, wherein said valve element and seat have opposed, substantially flat surfaces which mate in said closed position of the valve element so that at low temperatures oil entrapped between said surfaces will be highly viscous and will cause i said surfaces to adhere together, whereby under cold engine starting conditions said valve element will substantially block the flow of gases from the crankcase to the intake manifold so that such flow will not upset carburetion at that time.

6. A flame arrestor for use in a crankcase ventilating conduit extending between the crankcase and the intake manifold of an internal combustion engine, said flame arrestor comprising a housing adapted to be disposed in said conduit, said housing have a passage therethrough forming a part of said conduit, a valve seat proximate said passage in said housing facing downstream for the normal direction of gas flow from the crankcase to the intake manifold, and a valve element comprising a sheet of resilient material supported in said housing with a portion thereof disposed on the downstream side of said seat and movable between an open position spaced from said seat where it is held by the flow of gases during normal engine operation when the intake manifold is at a lower pressure than the crankcase to permit the substantially unimpeded flow of blowby exhaust gases from the crankcase through the conduit to the intake manifold, and a closed position against said seat to block the flame front from the crankcase upon a pressure reversal resulting from backfiring in the engine fuel intake system, said sheet of resilient material being so arranged that its resiliency biases said portion thereof toward said seat,-whereby the position of repose thereof when the engine is inoperative and there is not pressure differential between the crankcase and the intake manifold is the closed position of said portion of the sheet of resilient material.

7. Aflame arrestor as defined in claim 6, wherein said resilient material has the physical characteristic that it stiffens and becomes substantially rigid at low temperatures corresponding to cold start engine temperatures, whereby under cold engine starting conditions said portion of the resilient sheet will be substantially rigid in its said closed position so as to substantially block the flow of gases from the crankcase to the intake manifold so that such flow will not upset carburetion at that time.

8. A flame arrestor for use in a crankcase ventilating conduit extending between the crankcase and the intake manifold of an internal combustion engine, said flame arrestor comprising a housing adapted to be disposed in said conduit, said housing having a passage therethrough forming a part of said conduit, a fire check plate supported in said housing so as to extend across said passage and having a plurality of gas flow apertures therethrough, and a resilient diaphragm supported in said housing on the side of said platewhich is downstream for the normal direction of gas flow from the crankcase to the intake manifold, said diaphragm being slit to provide a plurality of flap portions which are flexible between open positions spaced from said plate where they are held by the flow of gases during normal; engine operation when the intake manifold is at a lower pressure than said crankcase to permit the substantially unimpeded flow of blowby exhaust gases from the crankcase through the conduit and said apertures to the intake manifold, and closed positions seated against said plate in covering relationship over the respective said apertures to block the flame front from the crankcase upon a pressure reversal resulting from backfiring in the engine fuel intake system, said plate and diaphragm being so arranged that said flap portions are biased toward their said closed positions by the resiliency of the diaphragm material.

9. A flame arrestor as defined in claim 8, wherein said plate and diaphragm are generally disc-shaped, said apertures being at least three in number and being substantially regularly spaced about said plate at substantially the same radial distance from the center of the plate, and the diaphragm being slit radially outwardly from substantially the center thereof so that flap portions are generally triangular with apexes at substantially the center of the diaphragm.

10. A flame arrestor as defined in claim 9, wherein said diaphragm is substantially flat in its unflexed condition, and is held against said plate at its periphery, and wherein said plate is bowed toward the diaphragm so that said diaphragm flap portions are flexed in a downstream direction in their positions of repose against said plate, whereby said flap portions are biased against the plate.

11. A flame arrestor as defined in claim 8, wherein said resilient diaphragm has the physical characteristic that it stiffens and becomes substantially rigid at low temperatures corresponding to cold start engine temperatures, whereby under cold engine starting conditions said flap portions of the diaphragm will be substantially rigid in their said closed positions so as to substantially block the flow of gases through said apertures and hence from the crankcase to the intake manifold so that such flow will not upset carburetion at that time.

12. Apparatus for use in a crankcase ventilating conduit extending between the crankcase and the intake manifold of an internal combustion engine comprising: a flow regulator comprising a casing, a flexible diaphragm within the casing dividing into a first chamber and a second chamber, said first chamber having a gas inlet and a i i r a gas outlet adapted to be connected into said conduit so that gases flowing downstream through said conduit for the normal direction of gas flow from the crankcase to the intake manifold will flow through said casing from the inlet to the outlet, a valve nozzle inside the first chamber, one end of the nozzle communicating with the gas outlet, the other end of the nozzle terminating in an open end adjacent said diaphragm, the open end of the nozzle being at least partially blocked to the passage of gases therethrough by the diaphragm when the diaphragm is drawn to the open end of the nozzle by intake manifold negative pressures in the nozzle, and a spring supported in the casing biasing the diaphragm away from the nozzle to keep open said open end of the nozzle for outlet gas pressures equal to and more positive than a pre-selected gas pressure; and a flame arrestor comprising a housing adapted to be disposed in said conduit, said housing having a passage therethrough forming a part of said conduit, a valve seat proximate said passage in said housing facing downstream, and a valve element in said housing on the downstream side of said seat, said valve element being held by the flow of gases in an open position spaced downstream of said valve seat during normal engine operation when the intake manifold is at a lower pressure than the crankcase so that the valve element will not substantially interfere with control of the flow of blowby gases by the diaphragm, and the valve element being movable to a closed position against said seat to block the flame front from the crankcase upon a pressure reversal resulting from 'backfiring in the engine fuel intake system.

13. Apparatus as defined in claim 12, wherein said flame arrestor is on the downstream side of said flow regulator.

14. Apparatus as defined in claim 13, wherein said flame arrestor housing comprises an extension of said flow regulator casing.

15. Apparatus as defined in claim 12, which includes means lightly biasing said valve element toward said seat, whereby the position of repose of said element when the engine is inoperative and there is no pressure differential between the crankcase and the intake manifold is the closed position of the element against the seat, said biasing means exerting a biasing force which is sufficiently light so that during normal engine operation said element will not substantially impede the flow of blowby exhaust gases from the crankcase to the intake manifold.

16. A flame arrestor as defined in claim 15, wherein said biasing means has the physical characteristic that it stifiens and becomes substantially rigid at low temperatures corresponding to cold start engine temperatures, whereby under cold engine starting conditions said biasing means will be substantially rigid with said valve element in its said closed position so as to substantially block the flow of gases from the crankcase to the intake manifold so that such fiow will not upset carburetion at that time.

17. Apparatus as defined in claim 16, wherein said valve element comprises a sheet of resilient material supported in said housing With a portion thereof movable between said open and closed positions, said sheet being so arranged that the resiliency thereof provides said biasing means.

References Cited by the Examiner UNITED STATES PATENTS 3,088,447 5/63 Henderson 123--119 KARL J. ALBRECHT, Primary Examiner.

Claims (1)

1. A FLAME ARRESTOR FOR USE IN A CRANKCASE VENTILATING CONDUIT EXTENDING BETWEEN THE CRANKCASE AND THE INTAKE MANIFOLD OF AN INTERNAL COMBUSTION ENGINE, SAID FLAME ARRESTOR COMPRISING A HOUSING ADAPTED TO BE DISPOSED IN SAID CONDUIT, SAID HOUSING HAVING A PASSAGE THERETHROUGH FORMING A PART OF SAID CONDUIT, A VALVE SEAT PROXIMATE SAID PASSAGE IN SAID HOUSING FACING DOWNSTREAM FOR THE NORMAL DIRECTION OF GAS FLOW FROM THE CRANKCASE TO THE INTAKE MANIFOLD, A VALVE ELEMENT IN SAID HOUSING ON THE DOWNSTREAM SIDE BY SAID SEAT, SAID VALVE ELEMENT BEING HELD BY THE FLOW OF GASES IN AN OPEN POSITION SPACED DOWNSTREAM OF SAID VALVE SEAT DURING NORMAL ENGINE OPERATION WHEN THE INTAKE MANIFOLD IS AT A LOWER PRESSURE THAN THE CRANKCASE TO PERMIT THE SUBSTANTIALLY UNIMPEDED FLOW OF BLOWBY EXHAUST GASES FROM THE CRANKCASE THROUGH THE CONDUIT TO INTAKE MANIFOLD, AND THE VALVE ELEMENT BEING MOVABLE TO A CLOSED POSITION AGAINST SAID SEAT TO BLOCK THE FLAME FRONT FROM THE CRANKCASE UPON A PRESSURE REVERSAL RESULTING FROM BACKFIRING IN THE ENGINE FUEL INTAKE SYSTEM, AND MEANS LIGHTLY BIASING SAID VALVE ELEMENT TOWARD SAID SEAT, WHEREBY THE POSITION OF REPOSE OF SAID ELEMENT WHEN THE ENGINE IS INOPERATIVE AND THERE IS NO PRESSURE DIFFERENTIAL BETWEEN THE CRANKCASE AND THE INTAKE MANIFOLD IS THE CLOSED POSITION OF THE ELEMENT AGAINST THE SEAT, SAID BIASING MEANS EXERTING A BIASING FORCE WHICH IS SUFFICIENTLY LIGHT SO THAT DURING NORMAL ENGINE OPERATION SAID ELEMENT WILL NOT BE SUBSTANTIALLY IMPEDE THE FLOW OF BLOWBY EXHAUST GASES FROM THE CRANKCASE TO THE INTAKE MANIFOLD.

Images