US3512510A - Multistage carburetor - Google Patents

Description

May 19, 1970 o. MANNING 3,512,510

I MULTISTAGE` CARBURETOR Fl'ed Nov.' 9, 1967 www Nm N INVENTOR. Wa. lA/1l O. MANN/N6 Patented May 19, 1970 3,512,510 MULTISTAGE CARBURETO'R William O. Manning, Plymouth, Mich., assigner to Holley Carburetor Company, Warren, Mich., a corporation of Michigan Filed Nov. 9, 1967. Ser. No. 681,868 Int. Cl. F02m 1]/04, 1]/10 U.S. Cl. 123-127 6 Claims ABSTRACT OF THE DISCLOSURE A carburetor, having primary and secondary induction passages with mechanically actuated primary and secondary throttle valves respectively situated in the induction passages, is provided with a pressure responsive diaphragm member exposed to engine vacuum and adapted to operatively engage the secondary throttle to prevent the opening of the secondary throttle during certain periods of engine operation.

BACKGROUND OF THE INVENTION Heretofore multibarrel multistage carburetors could be classified into two categories. The first would be, vacuum actuated, which would include all the carburetors wherein the secondary throttle valves are actuated (opened and closed) by pressure responsive means exposed to primarily venturi-generated vacuum. The second category would be, mechanically actuated, which would include all the carburetors wherein the secondary throttle valves are actuated (opened and closed) by mechanical linkages responsive to the vehicle operators movement of the foot throttle lever.

Usually, the mechanical linkages in such carburetors were provided with effective lever arms and/ or cams so as to cause the secondary throttle valves to open slower or later than the primary throttle valves. Nevertheless, in such situations when the vehicle operator causes the primary throttle to lbe suddenly opened from, for example, idle engine operation to a Wide-open-throttle (W.O.T.) position the secondary throttles are often caused to also become opened thereby providing a relatively large area for air flow. However, because of the differences in inertia of air as compared to the fuel, the resulting fuel-air mixture is too lean to adequately support combustion thereby causing stalling of the engine.

In View of the above, it is apparent that multistage multibarrel carburetors having mechanically actuated secondary throttle valves possess inherent characteristics which present definite problems to achieve smooth engine operation in all conditions of engine operation.

SUMMARY OF THE INVENTION The present invention comprises a multistage multibarrel carburetor, for an internal combustion engine, having mechanically actuated primary and secondary throttle valves respectively situated in primary and secondary barrels of the carburetor, and pressure responsive means exposed to engine vacuum for at certain times preventing the opening of said secondary throttle valve even though said primary throttle has been moved to W.O.T. position and even though mechanical linkage between said primary and secondary throttle would otherwise dictate the opening of said secondary throttle.

Accordingly, a general object of this invention is to provide, in a multistage multibarrel carburetor having mechanically actuated primary and secondary throttle valves respectively situated in said barrels, means responsive to engine vacuum for at times preventing the opening of the secondary throttle valve.

Another object of this invention is to provide, in a multistage multibarrel carburetor having mechanically actuated primary and secondary throttle valves respectively situated in said barrels, means responsive to engine vacuum for at certain times maintaining the secondary throttle valve closed and 10st-motion connecting means operatively connected to said primary and secondary throttle valves which permits said primary throttle valve to open even though said secondary throttle valve is maintained in a closed position.

Other more specific objects and advantages of the invention will become apparent when reference is made to the following description considered in conjunction with the drawings.

DESCRIPTION OF DRAWINGS In the accompanying drawings:

FIG. 1 is a side View, mostly in cross-section, of a multistage multibarrel carburetor employing the invention disclosed herein;

FIG. 2 is an enlarged fragmentary portion of the carburetor of FIG. 1, in cross-section, illustrating the application of the instant invention thereto;

FIG. 3 is a fragmentary portion of the arrangement of FIG. 2 and illustrating a modification of the invention; and

FIG. 4 is a view, similar to that of FIG. 3, illustrating another modification of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now in greater detail to the drawings, FIG. 1 illustrates a multistage carburetor 10 comprising a body 12 with at least one primary induction passage 14 and at least one secondary induction passage 16 extending therethrough and communicating with the induction passages of the engine intake manifold 17. 'Ihe air intake 18 provided for the primary induction passage 14 is adapted to be controlled by a choke plate 20 mounted on a rotatable shaft 22 whose position is controlled by a choke control assembly 24 (which may be mounted on the carburetor 10 or the vehicle engine) which includes therein temperature responsive means operatively connected to a linkage 26. When the temperature responsive means of the choke control assembly 24 cools, linkage 26 is moved upwardly causing lever 28, secured to choke shaft 22, to rotate clockwise resulting in the closure of choke valve 20.

A primary fuel bowl 30 is mounted on the body 12 oppositely to the secondary fuel bowl 32. The primary induction passage or :bore 14 has a venturi 34 formed therein with a main fuel nozzle 36 situated generally centrally thereof. The main fuel nozzle 36 communicates with the fuel within chamber 38 formed by the hollow fuel bowl 30 through conduits 42., 44 and 46 and metering restriction 48. The idle fuel system, which may include a port 50 and transfer port 52 opening into the induction passage 14, communicates with chamber 38 by rneans of conduits 54, 56, 58 and 60 and the metering restriction 62.

The secondary induction passage 16 has a venturi 64, a main fuel nozzle 66 and a throttle valve 68 which is manually actuated, as will become evident in view of the subsequent discussion, through suitable linkage means. The main fuel nozzle 66 communicates with chamber 70 of fuel bowl 32 by means of conduits 72, 74 and 76 and metering restriction 78. An idle fuel system, similar to the one in the primary passage, is comprised of a port 78 opening into the secondary bore of passage 16 and being supplied by conduits 80, 82 and 84 and metering restriction y86.

FIG. 2, an enlarged `fragmentary portion of FIG. l,

illustrates the manner and means whereby actuation of the primary and secondary throttles is accomplished.

The primary bore 14 contains the primary throttle valve 88 which is suitably secured to a throttle shaft 90, journaled within carburetor body 12, :for pivotal rotation therewith. Throttle shaft 90 extends beyond body 12 and such extension carries a throttle lever 92 rigidly secured thereto so that, for example, counter-clockwise rotation of lever 92 about the centerline of throttle shaft 90 causes like rotation of the primary throttle valve 88. Additionally, throttle shaft 90 carries a second lever 94 which is relatively loosely mounted thereon so that relative angular motion can readily be experienced as between the second lever 94 and throttle shaft 90. A torsion spring 96, wound generally about the extension of throttle shaft 90, is generally interposed between levers 92 and 94 so as to have its arms 96 and 98 in abutting engagement with levers 92 and 94, respectively.

A second throttle shaft 100, journaled in body 12, has secured thereto secondary throttle valve 68 and a secondary throttle actuating lever 102 each of which is rigidly secured to the shaft 100. A linkage 104 has its opposite ends 106 and 108 pivotally received in apertures 110 and 112 respectively formed through levers 102 and 94. A foot-operated throttle control lever 114 may be operatively connected to one end of control linkage 116 as through a suitable lever 118. The other end 120 of linkage 116 is pivotally received in an aperture 122 formed through lever 92. As foot lever 114 is rotated clockwise about a pivot point 124, lever 118 rotates clockwise causing linkage 116 to mo-ve to the left thereby rotating lever 92 and throttle shaft 90 counter-clockwise opening throttle valve 88. A throttle return spring 126 may be secured to a suitable support as at 128 and connected to primary throttle lever 92 as by means of :an aperture 130 formed therethrough.

A pressure responsive motor assembly 132, which may be secured to the carburetor as by a bracket 134 and screw 136, may be comprised of first and second housing sections 138 and 140 which cooperate to retain therebetween a pressure responsive diaphgram member 142. Chamber 144, formed generally by housing section 138 and pressure responsive member 142, contains a compression spring 145 therein which continually urges the diaphragm to the right. A motion transmitting member 146 is secured at one end to diaphragm 142 as by means of a ange 148 and plate 150 disposed on opposite sides of diaphragm 142 and secured thereto as by a peenedover portion 152, Chamber 154, formed generally by diaphragm 142 and housing section 140 is exposed to the atmosphere and in order to assure complete exposure to the atmosphere, a plurality of passages 156 may be formed throughhousing section 140. The other end 158 of linkage 146 is slidably received through an elongated slot 160 formed in secondary throttle lever 102. When rod 146 is maintained in the position illustrated, throttle lever 102 is held against rotation in the opening direction.

Chamber 144 of pressure responsive assembly 132 is in communication with a conduit 162 which leads to a ball check valve assembly 164. The pressure responsive assembly 132 may be provided with a conduit portion 166 for connection to conduit 162 and, if desired, a restriction 168 may be provided within conduit portion 166 for purposes of calibration.

The check valve assembly 164, which may be secured to carburetor 10 as by a bracket 170 and screw 172, is comprised of a body 174 with first and second passages 176 and 178 formed therein so as to be in communication with each other. One end of passage 176 is closed by means of a plug-like member 200 which also has a projection 202 formed thereon. A ball valve member and ball seat 206 are situated within passage 176 in a manner so as to have the ball valve generally between the seat 206 and projection or stops 202 of plug 200. Prefera- Cil 4 bly, the seat 206 is staked or notched as at 208 in order to provide a calibrated leak passage between ball valve 204 and seat 206. Passageway 178 communicates with one end of a conduit 210 which has its other end in communication with a source of manifold vacuum as illustrated by conduit 212.

OPERATION OF INVENTION Before discussing the operation in detail, it should be made clear that when either throttle is referred to as being closed a certain predetermined quantity of air flow exists past the throttle valves. The quantity of air is that necessary to maintain idle engine operation.

Assuming now that the internal combustion engine is self-sustaining and operating at idle condition, throttle valves 68 and 88 will be closed, as illustrated, and a manifold vacuum will be generated within the engine intake manifold 17 and communicated to both primary and secondary induction passages 14 and 16 below throttle valves 68 and 88. The manifold or engine vacuum, of a relatively high valve during idle, is communicated to conduit 212 and through conduit 210 to passage 178 of the ball check valve assembly 164. As a consequence, ball valve 204 is lifted on the seat 206 and the manifold vacuum is conveyed through seat 206, conduits 176, 162 and conduit portion 166 to chamber 144 of the pressure responsive motor assembly 132. The vacuum so directed to chamber 144 causes the diaphragm member 142 to move to the left against the force of spring thereby pulling the motion transmitting member 146 to the left as illustrated in FIG. 2.

If it is desired to accelerate from engine idle to some other engine speed, primary throttle valve 88 must be opened so as to permit more air and fuel to pass into the engine intake manifold. However, the opening of the primary throttle valve 88 is accompanied by a reduction in manifold vacuum. Accordingly, if it is assumed that primary throttle valve 88 is moved suddently from the engine idle position to a wide-open-throttle (W.O.T.) position, there will be a corresponding sudden reduction in manifold vacuum. If at this time the secondary throttle valve 68 were permitted to also go to wide-open-throttle position, high air flow would be occasioned through both primary and secondary induction passages 14 and 16. However, because of the greater inertia of the fuel, as compared to air, in, for example, conduits 76, 74 and 72 and conduits 46, 44 and 42, the mixture passing through the induction passages 14 and 16 into the engine intake manifold 17 would be too lean in fuel and consequently cause stalling of the engine.

In order to overcome such engine stalling, the invention herein disclosed contemplates the provision of pressure responsive means 132 for maintaining the secondary throttle valve 68 closed during certain predetermined engine operating conditions even though the mechanical linkage controlled by the manually positioned throttle lever 114 would indicate that the secondary throttle valve 68 should be fully opened.

As throttle lever 114, linkage 116 and arm 92 are moved in order to rotate primary throttle valve 88 counter-clockwise to a position equivalent to or approaching W.O.T., it can be seen that the value of manifold vacuum is quickly and substantially reduced. However, it should be remembered that immediately prior to the opening of primary throttle valve 88 high manifold vacuum was communicated to chamber 144 of pressure responsive means 132. Accordingly, as the primary throttle valve 88 is moved to the W.O.T. position, conduit 212 is exposed to a pressure, Po, more nearly approaching atmospheric pressure while chamber 144 remains at a high vacuum, Pm, which is a lesser pressure than Po. Therefore, a pressure differential of Pov to Pm is created across hall check valve 204 which causes the valve 204 to be urged against its seat 206. This serves to somewhat maintain the high manifold vacuum, Pm, within chamber 144 overcoming the force of spring 145 and maintaining linkage 146, lever 102 and secondary throttle valve 68 in the positions illustrated.

Since throttle valve 68 is held against movement by pressure responsive motor means 132, it follows that connecting linkage 104 and lever 94, to which end 108 of linkage 104 is connected, also cannot move from their respective illustrated positions. This is accomplished by having a torsion spring 96 situated generally about throttle shaft 90 and having one arm 97 abutably engaged with lever 94 and an other arm 99 abutably engaged with lever 92. Accordingly, it can be seen that torsion spring 96 serves as a lost-motion connection between levers 92 and 94. This becomes evident when one remembers that the pressure responsive device 132 holds the secondary throttle valve 68 closed while the primary throttle valve 88 is being moved to its W.O.T. position. At this time, of course, lever 92 is forced to rotate against the force of torsion spring 96 thereby permitting the lever 94 to remain in the position illustrated. In view of the above, it should be apparent that the maximum force developed in torsion spring 96 is insuflicient to overcome the force generated by the high manifold vacuum, Pm.

As previously mentioned, seat 206 is staked or notched as at 208 thereby providing a calibrated leak passage around ball 204. In this manner chamber 144 is, in a controlled rate, permitted to be exposed to the higher pressure P0. As more air passes through the leak passage 208 the value of the vacuum in chamber 144 diminishes or, in other words, the pressure Pm increases thereby enabling compression spring 145 to slowly move linkage 146 to the right thereby permitting the torsion spring 96 to slowly rotate lever 94 counter-clockwise resulting in the clockwise rotation of lever 102 and secondary throttle valve 68. The rate of rotation of the secondary throttle valve is, of course primarily dependent upon the restricting effect of ball valve 204 and the leak passage 208.

The retarding eiect on the opening of the secondary throttle valve 68 causes the primary induction to first experience the increased air ow. This, of course, causes a higher air velocity about the main fuel nozzle 36 and venturi 34 thereby resulting in a higher venturi vacuum which causes an increase in fuel ow out of the main fuel nozzle 36. As the vacuum in chamber 144 decreases torsion spring 96 slowly causes rotation of the secondary throttle valve 68 towards its W.O.T. position. Such a controlled rate of opening of the secondary throttle valve 68 permits the rate of air flow around throttle valve 68 to slowly increase at a rate which takes into account the inertia of the fuel so as to assure suiiicient fuel liow from either or both the secondary idle fuel system and the secondary main fuel system.

FIG. 3 illustrates a second embodiment of the invention. All elements which are like or similar to those of FIG. 2 are identified with like reference numbers.

An inspection of FIG. 3 shows that conduit 210, instead of communicating with conduit 212 as in FIG. 2, now communicates with` a transverse conduit 214 which, in turn, communicates with a generally vertical passage or chamber 216 which may `be formed in the body 12 generally `between the .primary and secondary induction passages 14 and 16. Another conduit 218 communicating with chamber 216 terminates at its other end in an aperture 220 downstream or on the engine side of primary throttle valve 88.

It can be seen that port 220 is below and in relatively close proximity to the edge of primary throttle valve 88. Consequently, during curb idle operating conditions (wherein the vehicle is standing but the engine is per- -mitted to operate at au idle condition) a high manifold vacuum, Pm, is applied to chamber 144 by means 'of inter-communicating conduits 218, 216, 214, 210, 178, 176, 162 and 166.

As the primary throttle 88 is quickly rotated counterclockwise toward W.O.T. position, the edge 222 passes beyond port 220 causing the port or aperture 220 to be exposed to air pressure approaching or substantially equal to atmospheric pressure.' It should be apparent, in comparing the embodiments of FIGS. 2 and 3, that the provision of a conduit 218 and port 220 enables the conduit 210 to be exposed to a higher pressure and in less time than that achieved by the embodiment of FIG. 2. That is, conduit 212 continues to be within the area of the then existing manifold vacuum as the primary throttle plate 88 rotates counterclockwise. However, in the embodiment of FIG. 3, the movement of the throttle valve 88 toward W.O.T. causes port 220 and conduit 218 to be exposed to atmospheric pressure then existing above or upstream of the throttle valve 88.

The general operation of the other elements as disclosed with regard to FIG. 2 is the same for the second embodiment disclosed in FIG. 3 and operation will not be repeated. It suffices to say that the pressure responsive motor means 132 serves to inhibit movement of the secondary throttle valve 68 during rapid movement of the primary throttle valve in the same manner as disclosed with reference to the embodiment of FIG. 2.

FIG. 4 illustrates a third embodiment of the invention. All elements which are like or similar to those of FIGS. 2 or 3 are identified with like reference numbers.

An inspection of FIG. 4 shows that the basic dierence existing between the embodiments of FIGS. 3 and 4 is the provision of a second conduit 224 which communicates at one end with chamber 216 and terminates at its other end in a port 226 in the induction passage 14 at a point somewhat above or upstream of primary throttle valve 88. Just as in the second embodiment of FIG. 3, the third embodiment does not contain the conduit 212 of FIG. 2.

With throttle valve 88 closed, conduit 220 is exposed to the high manifold vacuum under throttle valve 88; however, at the same time conduit 224 is exposed to the atmospheric pressure existing above throttle valve 88, The conduit 224 is of a controlled diameter, that is, it is selected in order to provide an atmospheric lbleed in order to more closely tailor the communicated engine vacuum to that value of vacuum required to maintain a satisfactory W.O.T. acceleration `from idle engine operation.

For example, if it is found that conduit 218 alone communicates vacuum to the pressure responsive motor means 132 of a value in excess of that sufficient to momentarily hold the secondary throttle closed, then an atmospheric bleed such as conduit 224 can be provided in order to diminish the valve of the vacuum communicated to the pressure responsive motor means 132.

Even though the invention has been disclosed as employing the ball check valve assembly 164, the invention can be practiced without the ball check Valve assembly 164 by having conduit 162 communicate directly with either conduit 212 or conduit 214. In such event, the restriction 168 would be calibrated so as to provide some delay before releasing the secondary throttle valve 68 from its closed position as during those situations wherein the primary throttle is quickly moved toward W.O.T. position.

However, the provision of a ball check valve assembly 164 as illustrated provides additional benefits to the entire system. For example, the calibrated restriction 168 can be eliminated thereby reducing the possibility of having restriction 168 become clogged with dirt or gasoline tars. The ball check valve assembly is not as prone to becoming 4clogged with dirt or gasoline tars because each time the ball 204 is raised passage 176 and seat 206 therein are subjected to a relatively sudden movement of air which keeps the passage 176, and seat 206 therein, along with the leak passage 208, clean of any foreign matter.

In the three embodiments disclosed the vacuum for the pressure responsive means 132 has always been obtained at a point in the primary induction passage downstream of the primary throttle valve 88. However, this should not be interpreted as limiting the invention to using only the primary induction passage 14 as the source of engine vacuum. In fact the invention should be considered as also embracing arrangements wherein the conduit for communicating vacuum (such as conduit 220 or conduit 212) to chamber 144 is exposed to the engine or manifold vacuum at a point below the secondary throttle valve 68. This is possible because whenever the primary throttle valve is moved toward a more nearly W.O.T. position the engine or manifold vacuum decreases and such decrease is evident in the secondary induction passage below the secondary throttle valve 68.

Further, the invention herein disclosed has been illustrated as being a part of or in combination with a multistage, multibarrel (induction passage) carburetor wherein each of the barrels or induction passages is provided with a venturi and main fuel nozzles situated generally within such venturi. However, the invention should not be considered as being so limited. For example, the invention herein disclosed is equally well suited for carburetors wherein the primary induction passage contains a venturi, with a main fuel nozzle therein, but wherein the secondary passage is devoid of a venturi and instead has an air valve situated anterior of the secondary throttle valve and adapted to control the ow of fuel out of fuel nozzles positioned generally between the throttle valve and air valve.

In other words, the invention herein disclosed is equally well suited for use in any multistage multibarrel carburetor having mechanically actuated primary and secondary throttle valves.

I claim:

1. A multistage carburetor for an internal combustion engine having an intake manifold, comprising a body; primary and secondary induction passages formed through said body; primary and secondary throttle valves located respectively within said primary and secondary induction passages and adapted to control the flow of combustible mixtures therefrom to said intake manifold of said engine; first means for manually controlling the position of said primary throttle valve; second means operatively interconnecting said primary and secondary throttle valves enabling said primary and secondary throttles to be at least at times simultaneously positioned by said first means; said primary and secondary throttle valves being respectively secured for rotation to first and second throttle shafts pivotally carried by said body; said first means comprising a first lever fixedly secured to said first throttle shaft for rotation therewith; said second means comprising a second lever mounted on said first throttle shaft for relative rotation thereabout, and being operatively connected to said first lever in order to at times be rotated by said first lever, and linkage means operatively connected between both said second lever and said second throttle shaft for at times transmitting motion from said first lever to said secondary throttle valve; and pressure responsive holding means in communication with a source of engine vacuum for at times operatively holding said secondary throttle valve in order to control said secondary throttle valve over a range of movement thereof in the opening direction.

2. A multistage carburetor according to claim 1, wherein said second means also comprises resilient motion transmitting means interconnecting said first and second levers, and including a third lever operatively connected to said second throttle shaft for rotation therewith, said third lever also being operatively connected to said linkage means whereby motion can be transmitted from said second lever to said secondary throttle shaft and said secondary throttle valve.

3. A multistage carburetor for an internal combustion engine having an intake manifold, comprising a body; primary and secondary induction passages formed through said body; primary and secondary throttle valves located respectively within said primary and secondary induction passages and adapted to control the flow of combustible mixtures therefrom to said intake manifold of said engine, said primary and secondary throttle valves are respectively secured for rotation to first and second throttle shafts pivotally carried by said body; first means for manually controlling the position of said primary throttle valve, said first means comprising a first lever fixedly secured to said first throttle shaft for rotation therewith; second means operatively interconnecting said primary and secondary throttle valves enabling said primary and secondary throttles to be at least at times simultaneously positioned by said first means, said second means comprising a second lever mounted on said first throttle shaft lfor relative rotation thereabout, a third lever fixedly secured to said second throttle shaft, a torsion spring having arm portions engaging said first lever and said second lever in a manner so that movement of said first lever toward the throttle-opening direction resiliently urges movement of said second lever in a direction the same as the direction in which said first lever is being moved, motion transmitting linkage means pivotally connected at one end to said second lever and pivotally connected at the other end to said third lever so as to cause said second throttle shaft and said secondary throttle valve to be rotated toward the throttleopening direction whenever said second lever is rotated by said first lever; and pressure responsive holding means in communication with a source of engine vacuum for at times operatively holding said secondary throttle valve in order to control said secondary throttle valve over a range of movement thereof in the opening direction, said pressure responsive means comprising first and second housing sections, a relatively flexible diaphragm generally peripherally retained between said first and second housing sections thereby forming first and second distinct but variable chambers, said second chamber being vented to ambient atmospheric pressure, a movable member connected at one end to said diaphragm to be moved thereby and connected at the other end to said third lever, a compression spring contained within said first chamber and acting against said diaphragm so as to continually urge said diaphragm in a direction resulting in a decrease in the volume of said second chamber; a flow control valve assembly; first conduit means operatively connected to said first chamber and said valve assembly in order to complete communication therebetween; second conduit means operatively connected to said valve assembly and to said source of vacuum in order to complete communication therebetween; and a valving member situated within said valve assembly so as to be generally between said first and second conduit means, said valving member being effective when closed to permit a calibrated flow of air past said valving member and also being effective when opened to permit a substantially unrestricted flow of air past said valving member.

4. A multistage carburetor according to claim 3, wherein said second conduit means includes la first conduit portion terminating in a first aperture formed in said primary induction passage at a point upstream of said primary throttle valve, and a second conduit portion terminating in a second aperture formed in said primary induction passage at a point downstream of and in 4close proximity to said primary throttle valve.

5. A multistage carburetor according to claim 3, wherein said second conduit means terminates in `at least one aperture in said primary induction passage at a point downstream of said primary throttle Valve.

6. A multistage carburetor according to claim 5, wherein said aperture is downstream of said primary throttle valve and in relatively close proximity to the edge of said primary throttle valve when said primary throttle valve is closed so as to be generally traversed by said edge when said primary throttle valve is moved toward a more nearly open position thereby exposing bient atmospheric pressure.

said aperture to a pressure more nearly approaching am- 2,837,322 6/ 1958 Thome et a1.

2,857,146 10/ 1958 Carlson. 3,396,948 8/ 1968 Stettner 123-127 X References Cited FOREIGN PATENTS UNITED STATES PATENTS 5 956,527 4/1964 Great Britain.

8/1953 Braun 123-127 1/ 1956 Smitley. AL LAWRENCE SMITH, Primary Examiner 10/ 1956 Smitley.

5/ 1957 Carlson 12S-12.7 X U.S. C1. X.R.

2/1958 Glynn. 10 261-23 2/ 1958 Smith.

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