US3271938A - Breather cap and dipstick combination for an oil filler pipe - Google Patents

Description

Sept. 13, 1966 F. e. REST ETAL BREATHER GAP AND DIPSTICK COMBINATION FOR AN OIL FILLER PIPE Filed June 5, 1963 INVEIEORS FREDEFEICK .REsT DAVID .NEWSTED United States Patent "ice 3,271,938 BREATHER CAP AND DIPSTICK (:QP/EBTNATiQN FOR AN 011. FHLLER PEPE Frederick G. Rest, Slrokie, and David R. Newsted, La Grange, Ill., assignors, by mesne assignments, to Allen Electric and Equipment Company, Kalamazoo, 'Miclr, a corporation of Michigan Filed June 5, 1963, Ser. No. 285,756 1 Ciaim. (Cl. 55385) This invention relates to an improved sealing cap useful as a cover for the oil filler tube or pipe of an automobile engine.

It has been common to provide for the intake of air into the crankcase of automobile engines through openings in a breather cap covering the oil filler pipe. In some automobiles, the oil dip stick fits into the oil filler pipe in which case the breather cap is usually attached to the top of the oil dip stick. For reasons to be explained, recent modifications of the fuel feeding sections of these engines for the purpose of burning crankcase vapors to minimize the production of smog-producing hydrocarbons has created certain problems in the design caps which fit over the oil filler pipes of automobiles.

Investigations conducted by State and Federal Governmental agencies indicate that automobile engine emissions are a major source of air pollution and smog in many large metropolitan areas. The case against such emissions is based on the finding that typical smog effects are produced by the solar irradiation of mixtures of hydrocarbons found in these emissions which can form smog mixtures at concentrations as low as several hundred parts per million parts of air.

While much of the air polluting automobile exhaust emissions are discharged through the tail pipes thereof, another important source of these emissions is the crankcase. The referred to investigations have indicated that whereas it was formerly believed that emissions from crankcases sometimes referred to as blowby contributed only a negligible proportion of the pollution produced by motor vehicles, they in fact are responsible for from 20% to 40% of the total hydrocarbons discharged by automobiles. Blowby emissions normally consist of approximately 85% by volume of unburned fuel-air mixture and the remainder exhaust products which are blown past the pistons into the crankcase.

The crankcase is usually provided with an exhaust tube sometimes called a road draft tube extending below the engine into the air stream, which produces a small negative pressure in the crankcase due to the aspirating effect while the vehicle is in motion. This slight pressure reduction causes clean air to be drawn into the crankcase through a breather tube which, as indicated above, is usually the oil filler tube covered by an apertured breather cap.

To prevent, or at least reduce, air pollution from this blowby source, several systems have been proposed by which the crankcase emissions are returned to the engine intake system for consumption during operation. This approach to the control of blowby emissions uses the negative pressure of the engine induction system to establish a positive flow of the crankcase emissions through the crankcase. Two general types of such control systems have been developed and are now in use. One of these is referred to as the variable-orifice metering system and the other is referred to as the direct vent tube system. In the variable-orifice metering system a tube Patented Sept. 13, 1966 of relatively small diameter connects the crankcase with the intake manifold. The direct vent tube system for preventing, or reducing, blowby emissions to the atmosphere utilizes a tube of relatively large diameter to connect the crankcase with the air horn of the carburetor or with the carburetor air cleaner.

An internal combustion engine employing these crankcase emission retarding systems operates like an air compressor pumping into a closed vessel. The successful functioning of such systems is dependent in large measure upon the internal pressures developed Within the engine, and development of proper pressures and air-fuel mixture ratios for efficient operation of the engine are influenced to a considerable extent by the amount of fresh air entering the crankcase through the breather cap which covers the crankcase breather tube. It thus becomes necessary to exercise close consistent control over the amount of air entering the breather cap in engines incorporating crankcase emission retarding systems. One difliculty in obtaining this control is the difficulty heretofore encountered in maintaining an effective seal between the portion of the breather cap which fits over the oil filler pipe due, among other things, to irregularities in the dimensions of the oil filler pipes made for a given automobile model and the difficulty in properly manually seating the breather cap on the oil filler tube to provide a good seal. The presence of an imperfect seal will affect the amount of air entering the oil filler pipe since the air can then enter the pipe both through the breathing holes provided in the cap and through the clearance space left by the imperfect seal.

It has also been proposed to seal off the oil filler pipes of automobiles from the atmosphere and to draw the crankcase vapors into the engine intake manifold or directly into the carburetor through the oil filler pipe cap, which also requires a tight seal between the cap and the oil filler pipe.

An object of the present invention is to provide a breather cap preferably to be carried by the oil filler pipe of an automobile engine which enables close consistent control over the amount of air entering the oil filler pipe. A related object of the present invention is to provide a cap to be carried by the oil filler pipe which can with ease be applied in tight sealing relation with the oil filler pipe and wherein the obtainment of a tight seal is not adversely affected by irregularities in the size and shape of the oil filler pipe.

Another object of this invention is to provide a cap satisfying the aforesaid objectives and which can be mass produced from low cost easy to assemble parts, particularly die stamped metal parts and molded seal forming elastomer-ic parts made with simple, relatively inexpensive molds. A related object of the invention is to provide a cap as described where the air seal-forming element of the cap is formed by a separate piece which can easily be assembled with other parts of the cap and allows substantial freedom in the design of the other partn of the cap.

Briefly, in the preferred breather cap application of the present invention, the breather cap comprising an inverted cup-shaped cap member which carries a filter retained in position internally of the cap member by an open-ended sleeve having a flange at the bottom thereof. The bottom face of the flange has an annular depression or trough which intersects a plurality of spaced air passage holes in the flange which direct the air to the filter. The bottom of the flange is covered by a Hat annular member provided with a small breather opening which opens onto the annular depression in the sleeve flange. The sleeve flange holes are fairly well distributed over the extent of the trough, and so the possible path lengths between the small breather hole and the nearest air pasage hole of the annular trough will not vary over too wide a range for different relative angular positions of the annular member and the sleeve flange. Precise positioning of these parts in assembly of the breather cap is thus not required.

The annular member has attached to the inner perimeter thereof a resilient, extremely pliant sealing ring. The ring is a thin walled, upwardly directed and tapering member which readily receives and closely conforms in air tight relation to the outer wall of irregularly sized and shaped oil filler pipes made within normal manufacturing tolerances commonly used in the construction of these pipes. An appreciable clearance space is provided for the flexure of the tapered sealing ring. The ring is further provided with a continuous raised annular ridge which sealingly engages with the flange inside of the annular trough thereof, to prevent air which enters the annular trough from by-passin'g the air passage holes leading to the filter.

Although some aspects of the invention are not so limited, the use of the aforesaid flat annular member as a carrier for the sealing ring enables the sealing ring to be molded in place on the annular member using simple dies. Also, the placement of the sealing ring on a separate carrier member formed by the exemplary annular member leaves substantial freedom in the design of the other parts of the cap.

Further objects, advantages and features of the present invention will become more readily apparent as the following description proceeds taken in conjunction with the accompanying drawing wherein:

FIG. 1 is a vertical sectional view of a breather cap embodying the improvements of the present invention;

FIG. 2 is a bottom plan view, with a portion brokenaway, of the breather cap illustrated in FIG. 1 showing the relationship of the various elements of the assembly;

FIG. 3 is a fragmentary vertical sectional view corresponding to the view shown in FIG. 1 with the breather cap mounted on an oil filler pipe;

FIG. 4 is an enlarged fragmentary sectional view of a portion of the breather cap illustrated in FIG. 1 showing the relationship of the elements of the assembly prior to positioning the cap on an oil filler pipe;

FIG. 5 is an enlarged fragmentary sectional view corresponding to the view of FIG. 4 showing the relationship of the elements of the assembly when the cap is mounted on an oil filler pipe;

FIG. 6 is a View in perspective of the flat annular member to which is attached the resilient sealing ring of the breather cap illustrated in FIG. 1; and

FIG. 7 is a view in perspective of the flanged sleeve of the breather cap illustrated in FIG. 1.

Referring now to the drawings, the breather cap assembly there shown and designated generally at 10 comprises an inverted cup-shaped cap member 12, desirably a die-stamped metal member having an outwardly extending shoulder 14 at the bottom of the cap member and a skirt portion 16 depending a short distance from the outer margin of the shoulder 14. Internally of the cup-shaped cap member 12 there is provided an open-ended flanged sleeve 20 having a substantially cylindrical portion 22 spaced from the side walls of the cup-shaped cap member 12. The cylindrical portion 22 of the sleeve 20 is joined to a flange portion 24 extending outwardly from the bottom thereof. The cylindrical portion 22 and the flange portion 24 of the sleeve 20 advantageously form a radius 26 at their juncture, the lower end of said vertical wall thus being above the lower end of the vertical side wall of the cup member 12, the function of which will become clear as the description proceeds. The end of the cylindrical portion 22 remote from the flange portion 24 has an inwardly extending shoulder 28 which defines an opening 29 and serves to intercept the rim 30 of an oil filler tube or pipe 32, as illustrated in FIG. 3, thereby maintaining an air space 34 above the mouth of the pipe 32 through which filtered air can pass into the top of the oil filler pipe.

The bottom face of the flange portion 24 of the sleeve 20 desirably has a depression or trough 36 provided with a number of air inlet openings 38, four such openings spaced apart being shown in the illustrated embodiment of the invention. While optimum effects are achieved with this number of holes, perhaps only three, and many more than four holes could be utilized with good results. The flanged sleeve 20 may be constructed of any durable material, die-stamped metal being preferred.

The flange portion 24- of the sleeve 20 receives a flat annular member 4a which advantageously has attached to the inner margins thereof defining an opening 42, a thin walled, resilient and highly pliant sealing ring 44. The sealing ring 44 may be fabricated of various materials such as, for example, rubber or rubber-like compositions, and can be secured to the annular member 40 during the molding of the sealing ring in any manner known to the art. A very satisfactory bond between the ring 40 and the sealing member 44 can be easily attained by employing conventional vulcanization techniques. Other methods of attachment such as for instance, gluing, may, of course, be utilized, but are less desirable.

Referring now in particular to FIGS. 4, 5 and 6 of the drawing, the sealing ring 44 desirably has a substantially fiat annular portion 46 which is attached to the fiat upper face of the annular member 40. At the perimeter of the flat portion 46 of the sealing ring 44 is a continuous raised annular ridge 48, which presses against the radius 26 of the sleeve 20 at a point inwardly of the flange depression 36 to prevent escape of air inwardly of the trough. The annular member 40 covers the trough 36 to define therewith an annular air circulation pass-age or channel 50 which receives air from a small air intake hole 52 formed in the annular member 40.

The inner margin of the flat annular portion 46 of the sealing ring 44 forms an inwardly and upwardly extending, thin upwardly tapering, resilient and highly pliant wall portion 54- which at its smallest diameter defines a cylindrical opening 56 concentric with the opening 42 of the ring 40. The opening 56 of the wall portion 54 advantageously has a diameter less than the smallest expected dimension of the oil filler pipe 32 which due to irregularities in manufacture may deviate from a true cylinder (cg. oval-shaped) and engages in snug, air sealing relation the outer surface of the oil filler pipe 32.

The breather cap 10 has a filter 60 filling the space between the cylindrical portion 22 of the sleeve 20 and the cap member 12. The filter 60 may be conveniently constructed of any suitable material such as, for example, crimped copper wire. The filter 60 serves the conventional function of removing dust and the like from the air passing into the crankcase of the engine and, the space occupied by the filter is in communication with the space 34 leading to the open top of the oil filler tube 32 and atmosphere through opening 52 in the annular member 40, the annular space or channel 50, and the sleeve flange holes 38.

The flanged sleeve 20 and the annular member 40 are secured to the cup-shaped cap member 12 by crimping or spinning and bending the skirt portion 16 of the cap member 12 about the peripheral margins of the sleeve flange 24 and the annular member 40 to form an air tight joint.

In the preferred embodiment of the invention illustrated, the breather cap 10 desirably is provided with a U-shapcd leaf spring 70 the legs 72 of which are advantageously angled outwardly to a distance that exceeds the inner diameter of the oil filler pipe 32 and then inwardly from their point of greatest separation to permit the ends 74 of the legs 72 to receive the oil filler pipe 32 and to serve as guides therefor. Where the oil filler tube forms a receptacle for an oil dip stick 80 the breather cap of this invention is attached to the dip stick as by a rivet 86 and a washer 88 which also anchors the leaf spring 70 in place. The dip stick 80 has the usual markings (not shown) at the lower end thereof to indicate the level of the oil in the crankcase at any given time.

In utilizing the improved breather cap of the present invention, the dip stick 80 is guided into the mouth of the oil filler pipe 32 and lowered therein until the rim 30 of the pipe 32 rests against the shoulder 28 of the flanged sleeve 20. In this position the U-shaped spring 70 is biased inwardly causing a portion of the spring to be pressed against the inner wall of the pipe 32 whereby the breather cap 10 is held in snug frictional engagement on the pipe 32. As the cap 10 is guided on the pipe 32, the pipe passes through the opening 56 defined by the upwardly tapering wall portion 54 of the sealing ring 44. The curvature of the portion 26 of the sleeve provides a large clearance space for flexure of the resilient and highly pliant sealing ring portion 54 required to accommodate oil filler tubes of irregular size and shape. Since the diameter of the opening 56 is less than the smallest diameter of the pipe 32, the wall portion 54 is depressed outwardly and caused to lie in snug, gas sealing relation against the radius 26 of the flanged sleeve 20. The thin, resilient, pliant character of the sealing ring 44 and upwardly tapering shape enables the ring to be readily inserted in sealing relation on the oil filler pipe and to conform to irregularities in the outer Wall of the pipe 32 where it effectively and efficiently prevents any flow of air between the outer wall of the pipe and the sealing ring. The sealing ridge 48 of the ring 44 prevents air in the annular channel 50 from by-passing the filler 60 by flowing between the outer side of the sealing ring and the sleeve 20. Thus the flow of air into the crankcase can be closely controlled and metered, and cannot by-pass the filter 60.

The distribution of the openings in the flange 24 of the flanged sleeve 20 minimizes the variation in gas flow resistance through the openings 38 and the channel 50. Thus, in placing the annular member 40 on the flange portion 24 of the sleeve 20 during assembly of the breather cap, special care need not be given to the relationship of the opening 52 in the annular member 40 and the holes 38 in the flange portion 24. When the annular member 40 is in position on the flange portion 24, the opening will always be sufliciently close to a hole in the flange portion to permit ready, metered flow of gases into and from the crankcase of the engine.

It should be understood that numerous modifications may be made in the breather cap of the invention abovedescribed without deviating from the broader aspects of the invention. Also, the construction of the sealing ring 44 and its attachment to a carrier member separate from the other parts of the oil filler pipe cap is applicable to the type of cap which is completely sealed from the atmosphere.

What is claimed is:

A cap for the oil filler pipe of a motor vehicle, said cap comprising:

a cup-shaped member having a cylindrical, substantially vertical side wall, a closed upper end and an open lower end, said cup member having an outwardly extending annular shoulder adjacent the open lower end thereof and an annular skirt portion extending a short distance axially beyond the outer margin of the shoulder and integral with said shoulder;

a dipstick and a leaf spring disposed in said cup member and fixed to the closed upper end thereof by a rivet and washer, said dipstick and leaf spring extending from said closed end through said open end of said cup member and being adapted for insertion into said oil filler pipe upon placement of said cap thereon;

an open ended, flanged sleeve encompassed by, concentric with and carried by said cup member and having an annular vertical Wall defining an opening therein for receiving the oil filler pipe, said vertical side Wall of said cup member and said annular vertical wall of said sleeve being spaced apart from one another and defining an annular chamber therebetween, said sleeve having an annular flange attached to and extending from the lower end of said annular vertical wall into contact with said skirt portion of said cup member, the lower end of said annular vertical wall being above the lower end of said vertical side wall of said cup member, said flange having at least three similar air passage openings distributed thereover;

an annular filter for said cup member, said filter substantially filling said annular chamber and being retained in position in said annular chamber by said flange, the upper end of said annular vertical wall being spaced apart from both said vertical side wall and said closed upper end of said cup member and defining a passage therebetween, said annular chamber communicating with the space encompassed by the annular vertical wall of said sleeve through said passage;

thin, flat and annular sealing ring carrier member underlying said flange and having an air intake opening generally similar in size to said air passage openings, said air passage openings in said flange being evenly spaced from one another to minimize variation in the resistance to air flow characteristics with a variation in the relative angular positions of said annular carrier member and said annular flange, the outer edge of said carrier member engaging said skirt portion, said skirt portion having an annular bent over portion Which clamps said carrier member and said flange between said bent over portion'and said annular shoulder, the inner diameter of said carrier member being slightly less than the inner diameter of said annular vertical wall;

a resilient, pliant and sealing ring attached to said carrier member and disposed in said oil filler pipe receiving opening, said sealing ring having an opening therein for receiving the oil filler pipe and bounded by a pliant, upwardly converging wall portion, said wall portion being thin measured in a radial direction, said wall portion extending inwardly of said annular, vertical wall, the upper end of said upwardly converging wall portion being spaced apart from said annular vertical wall and said annular flange, the inner margins of said sealing ring wall portion being of lesser diameter than the smallest expected dimension of the oil filler pipe and being readily expandable to form an air tight seal with an irregularly shaped oil filler pipe to prevent air from by-passing the filler pipe, there being a substantial clearance space outside of said sealing ring for the outward expansion of said sealing ring when applied over said oil filler pipe;

portion of said sealing ring together with said annular flange and said annular carrier member defining an annular channel in said cup member which communicates with the atmosphere through said air intake opening and with the space occupied by said filler through said air passage openings in said annular wall, said annular channel being formed by a depressed portion in said annular flange spaced away from said annular carrier member, said sealing ring having a continuous annular ridge which seals against said annular flange at points inwardly of the inner margin of said annular channel to prevent air entering the annular channel from by-passing the filter chamber, said carrier member and said annular flange being spaced apart at all points except for those portions of said annular flange and said carrier member which are clamped between said bent over skirt portion and said annular shoulder.

References Cited by the Examiner UNITED STATES PATENTS 2,056,755 10/1936 Welch 123-4186 2,073,156 3/1937 Kamrath 55-507 2,084,652 6/1937 Owen 55507 X 2,154,072 4/1939 Kamrath 55504 2,532,888 12/1950 Brown 55504 X 2,653,717 9/1953 Stomer 99-292 X 2,675,886 4/1954 McMullen 55507 2,789,840 4/1957 Sebok 55--507 Price 55-507 Henchert 22046 Wilber 55504 X Pritchard 55-502 X Goulet et a1. 55--510 McMahon 123198 X Jones.

Humbert et a1. 55498 Baldwin 210-462 X FOREIGN PATENTS HARRY B. THORNTON, Primary Examiner.

D. TALBERT, L. H. MCCARTER, Assistant Examiners.

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