US 3354898 A
Description (OCR text may contain errors)
Nov. 28, 1967 w. I. BARNES 3,354,898
CRANKCASE VENTILATING VALVE HAVING ROTATABLE METERING PLUNGER Filed May 2, 1966 2 Sheets-Sheet 1 ATTORNEKS' W. l. BARNES Nov. 28, 1967 CRANKCASE VENTILATING VALVE HAVING ROTATABLE METERING PLUNGER 2 Sheets-Sheet 2 Filed May 2, 1966 MO'ld SOOBSVE) INVENTOR William I. Barnes United States Patent 3,354,818 CRANKQASE VENTILATING VALVE HAVING ROTATABLE METERING PLUNGER William I. Barnes, Birmingham, Mich, assignor to Standard Screw Company, a corporation of New Jersey Filed May 2, 1966, Ser. No. 546,995 7 Claims. (Cl. 137-331) ABSTRACT OF THE DKSCLOSURE A flow meteringvalve adapted for use in an automotive crankcase ventilating system comprising a generally elongated valve housing having an inlet end, an outlet end, and a bore provided with a restricted portion intermediate its ends to form a metering orifice. A generally elongated metering plunger is provided in the bore of said housing and a sealing member is disposed adjacent the inlet end of said housing, said plunger and said sealing member being magnetically attracted to prevent flow through said valve until a predetermined flow pressure is attained. A spring is movably mounted in said housing and yieldably supports the plunger after the predetermined flow pressure has been attained to permit axial movement of said plunger relative to said orifice in response to changes in pressure in said valve housing.
This invention is a continuation-in-part of application Serial No. 436,439 filed March 2, 1965, now abandoned.
This invention relates to fluid flow control and more particularly to metering valves adapted for use in positive crankcase ventilating systems for engine operated vehicles so as to materially reduce discharge into the atmosphere of smog inducing blow-by accumulating in the crankcase.
One system of attaining positive crank-case ventilating involves the use of a conduit communicating the crankcase with the intake manifold so that the manifold vacuum will draw air and the blow-by through the conduit from the crankcase and deliver the blow-by laden air back to the cylinders. However, the performance of the engine will not be satisfactory unless the prescribed amount of air for the selected carburetor setting can be controlled in a continuous flow.
Accordingly, it is necessary to provide some means to precisely meter the flow. One type of device which has been found generally suitable for positive crankcase ventilation is a spring loaded valve having a plunger of a varying cross section along its length cooperating with a metering orifice provided in the bore of the valve housing. This plunger moves axially in the bore in response to changes in pressure in the manifold and the movement of the plunger varies the size of the effective fiow metering orifice.
A metering valve of the type described above must be capable of permitting delivery of a prescribed amount of the blow-by laden air in a continuous manner without interfering with proper engine performance, and must maintain this capability despite the fact many different types of engines are to be served. Thus, it is the practice of engine manufacturers, to assure as little interference as possible with proper engine performance, to require that these valves produce a smooth flow curve when tested to determine the fluid flow under various pressure differentials across the valve, and it is required that the valves do so with the limits of the flow curves by the manufacturer for each of its engines.
It was found that one of the problems with spring loaded valves of the type having a free floating pin, particularly those designed to center the pin to prevent the pin from contacting the valve housing and the walls, was axial oscillation or jiggling of the metering plunger under 3,354,893 Patented Nov. 28, 1967 operating conditions caused by pressure fluctuations. Such oscillations created such instability of the metering pin or plunger as to cause irregular rather than smooth fiow curves. To solve this problem, the spring which surrounded the plunger was arranged so as to cock the plunger in the bore of valve housing so that the pin would rub against wall portions of the metering orifice, and thus dampen out the inst-ability of the plunger during metering of the flow. In arranging the spring so as to cant the plunger in the axial bore of the valve housing, one means found satisfactory was to laterally offset the innermost coil of the spring and to make this coil of a size so that it would embrace the plunger about the pin adjacent the head portion in a press fit.
A problem that occurred with valves of the type described above was the build-up on the metering plunger of sludge or gunk present in the blow-by passing through the valve body. If too much gunk became deposited on the plunger this would also interfere with proper engine performance due to a decrease of the flow through the valve.
Accordingly, the primary aim of the present invention is to provide means to prevent an undesirable build-up of gunk on those portions of the canted plunger which do not ordinarily rub against the wall portion of the metering orifice.
A further problem occurred in the starting of an engine utilizing valves of the type described above. It is well known that a large volume of air flow is required when the intake manifold vacuum is low during maximum throttle conditions. However, during starting of the engine, when the intake manifold vacuum is also low, an excessive amount of air passes through the valve from the crankcase causing a leaning out of the air-fuel ratio, and therefore, poor starting conditions.
It is, therefore, another aim of the present invention to provide a means which shuts off the flow of air through the valve when starting the engine and, thereafter, permits the air to attain a normal flow.
Briefly summarized, the present invention provides a flow metering device utilizing a spring loaded plunger. The spring is a compression spring provided with a laterally ofiset coil so as to cock or cant the plunger to dampen oscillations by reason of the plunger rubbing against adjacent wall portions of a metering orifice provided in the bore of the valve housing. Means are provided on the plunger to frictionally receive the laterally offset coil of the compression spring yet to permit free rotation of the plunger relative to the laterally otfset coil. As a consequence, in operation, the plunger will rotate in the valve housing and metering orifice and substantially all portions of the periphery of plunger that cooperate with the orifice in metering the flow will rub against wall portions of the orifice and prevent any material depositing of gunk on the corresponding portions of the plunger.
As a further aid in the prevention of build-up of gunk on the valve assembly, the metering orifice may be made of a plastic material and the plunger may be chromeplated.
Further, a magnetic backfire washer may be provided adjacent the inlet end of the valve structure, the magnetic properties of the washer being such that the steel plunger is held fast against the washer to shut off air flow until a predetermined manifold vacuum is obtained, at which time the plunger will lift off the washer and assume its normal fiow position.
Reference is now made to the accompanying drawings for a better understanding of the nature and objects of the present invention, these drawings being but an illustration of the best mode contemplated by the applicants for carrying out the invention, but not to be taken as restrictions or limitations on its scope.
FIG. 1 is a skeleton elevation of a typical installation of a positive crankcase ventilation system;
FIG. 2 is a vertical sectional view, with portions in elevation for purposes of illustration, showing a valve structure incorporating the present invention with the metering plunger and spring assembly disposed in the position it assumes when the automotive engine is being accelerated;
FIG. 3 is a view like FIG. 2, showing the position of the metering plunger and spring assembly when the engine is idling;
FIG. 4 is also a vertical sectional view like FIG. 2, showing the position of the plunger and spring assembly in the event of backfire in the engine;
FIG. 5 is an elevational view of the metering plunger for the valve structure shown in FIGS. 2, 3 and 4;
FIG. 6 is an end elevational view of the valve structure shown in FIGS. 2, 3 and 4 taken from the inlet end of the device;
FIG. 7 is a cross section on line 77 of FIG. 2;
FIG. 8 is a cross section on line 8-8 of FIG. 3; and
FIG. 9 is a graphical representation of two flow curves obtained for this type engine utilizing the present invention.
Reference is now made to the details of the invention wherein, it will be noted as shown in FIG. 1, the valve, generally indicated by reference numeral 10, may be suitably attached to the rocker arm cover 12 of the en- :gine with the outlet end 18 up. A flexible tube or hose 14 may be coupled at one of its ends to the outlet end 18 of the valve structure and at its other end to the intake manifold 16 of the engine. However, these means for interconnecting the parts of the positive crankcase ventilating system form no part of this invention since these essentially plumbing details are well known to those skilled in the art.
The inlet end 20 of the valve structure is provided with a countersink 22 in the axial bore of a generally cylindrical housing 24 to receive a back-fire washer 26 fitted into the countersink. Washer 26 may be permanently fixed in countersink 22 or the latter may be provided with an annular groove 28 to receive a generally C-shaped retainer clip 30. The clip 30 seats in the groove 28 abutting adjacent portions of the back-fire washer 26 disposed inwardly of the retainer clip 30. The retainer clip 30 may be provided with means to facilitate removal of the clip with a suitable prying tool such as laterally extending fingers 32.
The bore of the housing 24 is reduced in cross section intermediate the inlet and outlet ends of the valve structure as best shown in FIGS. 2, 3 and 4. The junction of the reduced portion of the bore of the housing with the portion of larger cross section defines a metering orifice 34 provided for cooperation with a generally elongated solid metering plunger 36 to meter the flow of crankcase blow-by through the bore of housing 24.
The metering plunger 36 has an end portion 38 of reduced cross section which as it extends inwardly joins with an intermediate portion 40 of the body of the plunger. The port-ion 40 progressively increases in cross section in the direction of the opposite or inlet end of the metering plunger and merges with another intermediate portion 42 which may progressively increase in cross section in the direction of the inlet end of the plunger, as shown in the drawings, or which may be of a uniform diameter.
It will be noted that the metering plunger 36 is of a length that the end portion 38, which constitutes the outlet end of the plunger, is within the confines of the orifice 34 in all positions of operation. Further, the end portion 38 and the intermediate portions 40 and 42 constitute the effective portions of the plunger for varying the size of the orifice for metering purposes as the plunger moves axially to and fro in response to the changes in pressure in the manifold,
Adjacent the intermediate portion 42, in the direction of the outlet end of the pin, the metering plunger is provided with a further portion 44 which is of reduced cross section, relative to portion 42, and merges with a portion 46 of a progressively increasing cross section toward the inlet end of the plunger.
The inlet end of metering plunger 36 is provided with an enlarged portion 48 constituting a head portion. Inwardly of the head portion 48, the metering plunger is provided with an annular groove or undercut 50 constituting a seat to receive a laterally offset coil 52 of a compression spring 54 in the bore of the housing. This construction permits free radial rotation of the plunger relative to the spring and yet resists axial movement of the plunger. Coil 52 of the compression spring may be laterally offset relative to the intermediate coils 56 and an outermost coil 58, the coils 56 and 58 being concentrically disposed relative to each other. Spring 54 normally urges the plunger in the direction of the valve inlet 20.
By providing the metering plunger 36 with the undercut 50, between the head portion 48 and the enlarged portion 46, the laterally offset coil 52 fits into the undercut and thus cocks the metering plunger so that it is not centered in the bore. The coil 52 fits in the undercut relatively loosely, thus permitting substantially free radial rotation of the metering plunger 36 relative to the coils of the compression spring 54.
It is to be understood that it is not absolutely necessary that coil 52 be laterally offset, as long as it performs the function of cocking the plunger so that it rubs against a portion of the metering orifice. For example, the coil 52 could be coaxial with the remaining coils, but bent in a manner to urge the plunger into the above mentioned position.
The outermost coil 58 of the compression spring while coaxial with the intermediate coils 56 is of a lesser diameter. This coil 58, when the valve is in operation, abuts a stop shoulder 60 formed at the junction of the restricted portion of the bore of the valve housing 24.
It will be noted that the metering plunger and spring assembly and the back-fire washer 26 may be effectively and removably retained within the valve housing 24 by the C-shaped retaining clip 28, which as stated above can itself be removed by a prying tool manipulated against the laterally offset fingers 32.
As a further aid in preventing the build-up of gunk in the valve assembly, at least the portion of the bore defiining the metering orifice may be made of a plastic such as nylon, this material being utilized due to the fact that nylon has a resistance to sludge and varnish that tend to form in the valve assembly. For similar reasons, the plunger 36may be chrome-plated in addition, or as an alternate, to making the bore of nylon.
In operation, as best shown in FIGS. 2 and 3, the metering plunger is axially displaced to and fro in response to pressure changes across the valve, and the desired quantity of flow is metered by variations of the effective size of the metering orifice 34 defined by the mouth of the restricted portion of the bore of valve housing 24. Due to the laterally offset coil 52 seated in the undercut 50, the metering plunger 36 is cocked or canted so that portions along the length of one side of the plunger rub against the adjacent portion of the walls of the metering orifice while the side of the plunger opposite from the side riding against the wall portion is spaced from all wall portions of the orifice to permit fluid flow through said space. Inasmuch as the plunger is rotatable within the compression spring 54, the rubbing will occur throughout the periphery of the effective flow metering portions of the metering plunger along its length, thus preventing an undue build-up of gunk on such portions of the plunger. What is more, there are different relative motions or movements in the spring and plunger assembly in that not only does the entire assembly rotate with respect to the adjacent walls of the valve housing, but the plunger rotates within the spring.
According to another feature of this invention, the backfire washer 26 may be of a magnetic material and plunger 36 of steel, in order that the plunger may be held fast against the washer during engine starting until a predetermined vacuum is obtained across the valve. As stated earlier, this eliminates the passing of an excessive amount of air through the valve from the crankcase during starting which causes an undesirable leaning out of the air fuel ratio. Referring to FIG. 9 of the drawings, a pair of engine flow curves obtained utilizing this magnetic washer are depicted, the solid curve representing the flow obtained as the intake manifold vacuum increase from a zero vacuum to a positive vacuum, and the broken curve representing the flow obtained as the vacuum decreases from this positive vacuum to zero vacuum.
As seen from the curves, a large volume of flow from the crankcase to the intake manifold is required when the intake manifold vacuum is relatively low which normally occurs during maximum throttle conditions as shown by section B-C of the curve. Also, a smaller volume of emission flow is required when the intake manifold vacuum is high during minimum or idle throttle conditions as shown at section C-D of the curve. However, during the starting conditions shown at section AB of the curve, a problem exists due to the fact that, immediately upon a manifold vacuum being created while the engine is being started, an excessive air flow results which leads to an undesirable leaning out of the air-fuel ratio. The applicant has solved this problem by providing a backfire washer 26 of the proper magnetic properties so that plunger 26 is held fast against the washer during starting of the engine, thus eliminating air flow despite the existence of a low manifold vacuum during this time. As seen from section A-B of the solid curve obtained from this arrangement, the air flow remains at zero despite the manifold vacuum increasing from zero to a predetermined amount, which may be approximately 0.5 inch Hg. A vacuum in excess of this amount causes a force to be exerted against the plunger which is greater than that of the magnetic force, the plunger thus being released from the washer to assume its position during normal flow conditions as represented by section 13-1) of the curve. As the intake manifold vacuum decreases from a positive to a Zero value, the gaseous flow follows the broken curve as seen in FIG. 9.
It is to be understood that other variations of the above arrangement are possible as long as the above magnetic creating hysteresis is present. For example, the plunger could be magnetic and the washer of a material that is responsive thereto.
Accordingly, this invention results in a metering valve for positive crankcase ventilating system capable of long use without becoming clogged and capable of producing the desired flow of blow-by at all times without seriously afi'ecting proper engine performance.
What is claimed is:
1. A flow metering valve adapted for use in an automotive crankcase ventilating system comprising a generally elongated valve housing having an inlet end and an outlet end, said housing having a bore provided with a restricted portion intermediate its ends constituting a metering orifice, a generally elongated metering plunger in the bore of said housing, one end portion of said plunger extending into said orifice, a sealing member disposed adjacent the inlet end of said housing, said plunger and said sealing member being magnetically attracted to prevent flow through said valve until a predetermined fiow pressure is attained, and support means movably mounted in said housing, engaging said restricted portion of said housing, and yieldably supporting said plunger after said predetermined flow pressure has been attained to permit axial movement of said plunger relative to said orifice in response to changes in pressure in said valve hous'mg, said support means loosely engaging said plunger to permit relative movement between said support means and said plunger.
2. The combination defined by claim 1, including retaining means removably mounted in the bore of said housing to retain said plunger and support means in said housing.
3. The combination defined by claim 1, wherein said support means comprises a compression spring having a plurality of coils surrounding said plunger, one of said coils being laterally offset relative to the other coils and positioned around said plunger so as to cause portions of said plunger along its length to rub against portions of the wall of said orifice during axial movement of the plunger in response to a change of pressure.
4-. The combination defined by claim 3, wherein the side of said plunger opposite from the side riding against the wall portion is spaced from all wall portions of the orifice to permit fluid flow through said space.
5. The combination defined by claim 1, wherein said sealing member is a magnetic washer, the magnetic field of which attracts said plunger thereto.
6. The combination defined by claim -1, wherein said plunger is of a magnetic material, the magnetic field of which attracts the plunger to said sealing member.
7. The combination defined by claim 1, wherein at least the portion of the bore defining the metering orifice is of a plastic material and said plunger is chrome-plated.
References Cited UNITED STATES PATENTS 2,145,977 2/1939 Foster 251324 X 3,111,138 11/1963 Humphreys 137480 3,165,097 1/1965 Lowther 137483 3,198,208 8/1965 Tramontini 137480 3,199,524 8/1965 Mitchell 251 X 3,225,752 12/ 1965 Robinson 12 31 19 3,225,753 12/1965 Bintz 251-65 X 3,263,699 8/1966 Givler 137-480 ALAN COHAN, Primary Examiner.
HAROLD W. WEAKLEY, Examiner.