US3282261A - Gasoline engines - Google Patents

Description

Nov. 1, 1966 Filed Nov. 2, 1964 E. BARTHOLOMEW GASOLINE ENGINES 8 Sheets-Sheet 1 IFUGALAO CENTR ADVANCE NVENTDR:

ELU'ZBartholomew',7

VACUUM m H6 lp l5 Zaoo sooo ENGINE SPEED RPM ATTORNEY NOV. 1, '1966 E, BARTHOLQMEW 3,282,261

GASOLINE ENGINES 8 Sheets-Sheet 2 Filed Nov. 2, 1964 INVENTOR: EcULBczrthoZo/.new

ATTORNEY Nov. l, 1966 E. BARTHOL'OMEW GASOLINE ENGINES Fiied Nov. 2, 1964 8 Sheets-Sheet 3 arZBgr/wlmew Nov. l, 1966 E. BARTHoLoMEw 3,282,261

GASOLINE ENGINES Filed Nov'. 2, 1964 8 Sheets-Sheet 4 l NVNTOR ECWLBUFHL olomew ATTORNEY NOV 1, 1966 E. BARTHoLoMr-:w 3,282,261

y'GASOLINE ENGINES Filed Nov. 2, 1964 8 Sheets-Sheet 5 INVENTOR: Ear'L Bartholomew EQMWM 'ATTORNEY N0V- l, 1956 E. BARTHoLoMEw 3,282,261

GASOLINE ENGINES Filed Nov. 2, 1964 8 SheetsSheet 6 Qi y@ /NTAKE MAN/FOLD t940 BY MW ATTORNEY Nov. l, 1966 E. BARTHoLoMEw 3,282,261

GASOLINE ENGINES Filed Nov. 2, 1964 8 Sheets-Sheet, 'l

Il, l

TO SUCTION INVENTOR Earl Bartholomew ATTORNEY Nov. 1, 1966 E. BARTHoLoMEw 3,282,261

GASOLINE ENGINES Filed Nov. 2. 1964 s sheets-sheet a 501 `80E' 6g@ 60j 650 604 7 l l Mw j 306 Y INVENTOR: Earlartholomeuf ATTORNEY United States Patent O This application is in part a continuation of prior applications Serial No. 171,856 led February 8, 1962 (U.S. Patent 3,171,395 granted March 2, 1965), Serial No. 301,- 249 led August 12, 1963 (abandoned but replaced by Serial No. 445,856 filed March 29, 1965) and Serial No.

314,814 led October 8, 1963 (U.S. Patent 3,198,187 granted August 3, 1965).

The present invention relates to gasoline engines7 and particularly to induction and ignition systems used to supply the fuel-air mixture and the ignition spark to the cylinders of these engines.

Among the objects of the present invention is the provision of novel induction and ignition systems that are relatively simple yet provide improved and more eiiicient engine operation.

The above as well as additional objects of the present invention will be more fully appreciated from the following description of several of its exemplications, reference being made to the accompanying drawings wherein:

FIG. 1 is a side view partly broken away of a gasoline engine according to the present invention showing the carburetor part of the intake manifold and some control elements;

FIG. 2 is a graph showing a typical ignition timing arrangement exemplifying the present invention;

v FIG. 3 is a generally schematic illustration of the essential elements of a gasoline engine having a dual induction system pursuant to the present invention.

FIGS. 4, 5, 6vand 7 are generally schematic illustrations of dual intake manifold systems representative of the present invention;

FIG. 8 is a vertical sectional view partly broken away of the construction of FIG. 4 showing some of its internal details;

FIG. 9 is a generally schematic view -of a modified dual inducttion system illustrating another aspect of the present invention;

FIG. 10 is a sectional view of a carburetor control laccording to a still further modification of the invention; and

FIG. 1l is a vertical sectional view yof yet another induction system pursuant to the present invention.

According to the present invention a gasoline engine has a mixture intake system connected to provide (a) a fuel-air mixture which under non-choking conditions has an air-to-fuel Weight ratio not lower than about 14 except under high torque operation, (b) a throttle-closing check connected to limit the reduction of the rate of mixture o'w to the intake system to about 5-l0% per second when the throttle control is abruptly closed during high speed operation and the air flow rate reaches about 0.4 pound per |hour per cubic inch displacement, (c) an idle air flow rate about to 60% greater than minimum for no road load with 6 ignition advance before top dead center, and (d) ignition timing mechanism connected to retard the ignition to about 3 to 6 degrees after top dead center at idle, the timing mechanism having a vacuum advance system that provides essentially no vacuum advance when the throttle is in idle position.

The induction system can be arranged to heat the combustion mixture to a temperature of from about 160 to about 185 F. under light load conditions inasmuch as this enables smoother idling and low power operation. Arrangements can be provided to reduce the mixture heating under maximum torque conditions or the like.

3,282,261 Patented Nov. 1, 1966 Setting the idle air ow rate to about 20 t-o 60% above the rate ordinarily used is an important aspect of the present invention and it should be noted that the idle operation here referred to is the equilibrium or so-called hot idle after the system has completed its warm-up. The fast or cold idle generally used during warm-up is only effective for a very short time to minimize stalling during the period when the engine needschoking. It should be further noted that the higher idle air ow of the present invention is provided without increasing the idle r.p.m. to any significant degree or at all, as explained below, whereas the prior art cold idle has for its primary purpose the increasing of the idle r.p.m.

Combining the throttle-closing check with the increased idle air flow enables combustion to continue during periods of deceleration, regardless of the speed from which deceleration begins. Because of the continued combustion there is very little unburned or partially burned fuel components discharged through the exhaust during deceleration, the time when the discharge'of such undesirable emission is generally many times as high as during engine operation at constant speed. This has been the most diicult emission problem of the prior art and it is substantially completely solved by the very simple combination of increased idle air ow and throttle checking.

It is preferred to use hydraulic throttle checking rather `than throttle checking with a pneumatic dash-pot, al-

though both of them will give good results. Pneumatic dash-pots tend to be more non-uniform, particularly where the throttle is closed with large variations in closing force, and will show -an undesirable initial rebound. Such rebound should be taken into consideration in providing the 5 to 10% mixture reduction per second.

Checking can also be provided in other ways, as by applying the inertia of a rotating mass geared to the throttle shaft to rotate at high speed during the last few degrees of throttle closing. The inertia of such mass keeps the throttle closing from being too rapid.

Another alternative checking technique is to have the throttle shaft geared to a rapidly rotating vane whose rotation is slowed by air resistance as in a spring-wound musi-c box movement.

The addition of ignition retarding to the combination of high idle air ilow and throttle checking provides good engine braking during deceleration without loss of combustion thoroughness. Engine braking is lan important factor in practical automobile engines for example, and without it automobiles tend to be more difficult to control.

The further use of a lean fuel mixture with the foregoing combination makes the combustion so thorough that the exhaust shows exceedingly low levels of unburned and partially burned fuel ingredients during deceleration. An engine operated in this manner easily meets the emission limits set by the State of California in its anti-smog requirements.

The foregoing features can be used with either single intake manifold arrangements conventionally used in gasoline engines, or with the parallel-connected dual intake manifold arrangements described in the above-listed prior applications, for example. Such dual intake mani- Ifold systems are diflicult to operate smoothly, particularly from a cold start, unless there is adequate heating of the manifold that is only opened for high power use. For acceptably rapid warm-up the high power manifold has a heating surface or hot spot arranged to reach a ternperature of from about 300 to about 450 F. when the engine is operated from Ia cold start for `about 3 minutes under low-speed cruise conditions. During low-speed cruise this heating will warm the stagnant contents in the secondary manifold to an equilibrium temperature generally in the `range of from about to about 225 F.

u The low power or primary manifold preferably provides a mixture supply passageway with a cross-sectional area less than about Ss square inch lfor every 100 cubic inches of engine displacement, and is arranged to supply mixtures having an air-to-fuel Weight ratio of at least about 14 except under maximum torque conditions when the mixture can be richened to -a ratio of from about 12 to about 12.8. The foregoing manifold cross-section is adequate even when two successively firing cylinders are fed from the same manifold duct and have their intakes overlapping each other so that the duct is loaded a little heavier than otherwise. The heating of the mixture in the low power manifold can be to a temperature of from about 140 to about 185 F., preferably between 140 and 165 F. whether or not the high idle air rate and retarded spark combination discussed above is used.

According to lanother aspect of the present invention, the recirculation of exhaust to the intake manifold of a gasoline engine is throttled in such a way as to cut off the recirculation when the mixture intake throttle is at idle and to establish such recirculation lup to a maximum of 15% of the intake under all other throttle positions except at or near maximum open position. Such recirculation is very simply provided by merely having a recirculation throttle mounted on the same shaft as the principal throttle or the low power throttle in dual induction systems, so that both throttles operate together. The operation can be adjusted so that when maximum power is desired the exhaust recirculation is completely cut oif. At maximum throttle the combustion mixture is fairly rich and burns to give relatively small quantities of nitrogen oxides, so that exhaust recirculation is not needed then.

On the other hand, recirculation cut-off at maximum throttle is not needed in dual induction systems inasmuch as the exhaust recirculation is preferably proportioned to the low power or primary induction portion and when the high power or secondary induction system is brought into operation most of the induction takes Place through it so that the exhaust recirculation to the total intake is very small.

The interior of the secondary manifold should have a cross-sectional area at least as large as that of the primary manifold. By having the interior of the secondary manifold substantially larger than that of the primary manifold, the induction system will cause nearly all of the fuelair mixture to ow through the secondary manifold when the throttling system controlling these manifolds is wide open. For example, when the interior of the secondary manifold has a cross-sectional area about 21/2 times that of the primary manifold, about 80 to 90% of the fuel-air mixture will flow through the larger manifold during maximum throttle operation. Under such conditions it makes very little difference whether the smaller manifold is kept open or shut when the larger manifold is in use. Substantial simpliiication in the controls is effected by leaving the smaller manifold in use at all times.

Both manifolds of the dual induction systems of the present invention are open to each other at each of the engines intake ports and the terminations of the primary manifold at each intake port are preferably an average distance of about 1/3 to 1 inch from the intake valve seat. It is also very helpful to have the terminations of the primary `manifold above their respective intake valve seats.

The bypassing nature of the dual manifolds of the present invention also enables one manifold to act as equalizer for the other so that better induction is obtained, particularly with engines in which the suction strokes of adjacent positioned cylinders are not uniformly displaced. In a V-S engine having the firing order 1-8-4-3-6-5-7-2 for instance, there will be two pairs of adjacent cylinders whose intake strokes overlap through at least 90 of crankshaft rotation whereas other pairs of cylinders adjacent to each other will have their intake strokes spaced by 90 of inactive intake.

The acceleration pump normally used in gasoline en- 4 gines to improve the engines response to rapid opening of the throttle is not needed in the primary manifold of the dual systems of the present invention. Such a pump can be used in the secondary induction portion, however.

FIG. 1 shows an induction system having a single carbuertor 10 mounted on an intake manifold 12 and provided with a dash-pot 14 that acts as a check on the closing of the throttle valve 16. The checking action is hydraulic in nature, provided by a body of liquid in reservoir 18 that flows into the cylinder 20 through one-way valve 22 when a piston 24 is pushed out in the cylinder as by a compression spring 26. The piston has a piston rod 28 that carries an externally projecting nose 30 of polytetrauoroethylene, for example, positioned in the path of throttle-operating arm 32 which is fixed to the shaft 34 that carries the throttle valve 16. A linkage 36 connected to arm 32 controls the operati-on of the throttle valve.

Valve 16 is shown in idle position and is adjusted to provide an idle air flow about 20 to 60% greater than minimum for no road load with 6 ignition advance before top dead center. This is arranged by keeping the valve lips 3S, 40 from engaging the walls of the carburetor barrel 42, as by a conventional stop, not shown. The lenticular or crescent-shaped passageways thus formed between the lips and the walls allow the appropriate How of air. An idle fuel supply arrangement shown as including needle-controlled idle hole 44 and transfer idle holes 46, 4S are connected `to an idle fuel bleed passageway for this purpose.

The last 10 to 20 degrees of throttle valve closing is arranged to take place with the arm 32 pushing against the nose Si) of the check 14. During such closing the liquid in check cylinder 20 is squeezed back into reservoir 18 through a bleed passageway 50 that restricts the throttle closing rate to give the desired rate of air ilow lreduction mentioned above. A scavenging return as by means of a passageway opening at 52 in the lower portion of cylinder 20 outside the piston and at 54 in the reservoir permits the return of any liquid that may leak past the piston.

A vacuum supply hole 56 is also provided in the wall of carburetor barrel 42, and communicates through conduit S8 to ignition timing mechanism such as the standard vacuum -control system of an ignition distributor. The vacuum hole 56 is so located that it is substantially completely above the adjacent edge of throttle valve 16 when in idle position, and very little vacuum is produced during idle. only provide vacuum advance of the ignition when the vacuum in the control is greater (the pressure lower) than the small vacuum produced in hole 56 at idle as well as during at least the last vportion of a deceleration with the throttle in idle position.

FIG. 2 shows one ignition timing relationship suitable for use in connection with the construction of FIG. l. The basic timing of the ignition of this engine is set at 5 after top dead center with a speed-responsive advancing control such as the standard centrifugal weights and the vacuum-responsive advancing control described above. The vacuum control is shown as beginning to produce an ignition advance when the vacuum reaches about 6 inches of mercury, the advance increasing with increasing vacuum until at about 16 inches of mercury the ignition is at about 20 degrees before top dead center. This makes a total vacuum advance of 25 degrees. A limit is provided so that no further ignition advance is caused by additional increases in the vacuum.

Speed-responsive ignition advance is shown to start at about 600 r.p.m. engine speed, advancing it to 30 before top dead center at about 3400 r.p.m. This makes a total speed-control ignition advance of 35. It is preferred to have the speed-responsive ignition advance climb more steeply at the lower engine speeds, and FIG. 2 accordingly shows that the ignition is moved to about 15 The vacuum control is also connected to before topdead center when the engine speed reaches about 1600 r.p.ri'i. At higher speeds the advance can be made uniform or substantially so. The ignition timing advance mechanism can lbe connected in the usual Way so that the vacuum advance adds to the speed-responsive advance and either will be effective regardless of the other. The vacuum control can alternatively be connected so that when the throttle is closed at high engine or road speeds, the centrifugal advance is entirely or partially offset by a vacuum retard. This arrangement provides greater engine braking during deceleration and can be provided by an auxiliary retard control connected for operation only when the manifold vacuum reaches the particularly high levels (low pressures) that it attains during deceleration from high or medium speeds.

The induction system of FIG. 1 is preferably arranged to provide a relatively lean fuel mixture under all except maximum torque conditions. A particularly eifective arrangement is to have the idle mixture about 14 pounds of air per pound of fuel, with a main fuel jet providing a mixture of about 14.5 :1 and a power jet that increases the richness under maximum torque conditions to 12.5 or thereabouts. This type of operation will give a very low order of emission in the exhaust of unburned or partially burned fuel ingredients as well as of carbon monoxide. A feature of this low emission is that it is extremely low even during deceleration regardless of the speed from which deceleration takes place. Abrupt closing of the throttle control from speeds of 3000 r.p.m. -or even higher when an engine is used to operate an aut-omobile, for example, will cause the engine to keep firing during the resulting deceleration. At the same time the ignition will be sharply retarded by abrupt loss of all vacuum advance and if desired by the `auxiliary vacuum retard, so.that the power delivered by the engine during deceleration is sharply reduced and very effective engine braking is obtained.

Because of the relatively large opening of the lenticular passages at each end of the throttle valve 16, these passages are not as subject to variation through accumulation of deposits or the like, and the idle system described above does not need as many idle tune-ups as is found `desirable in conventional induction systems. However, if desired the throttle valve can be arranged to completely close with the idle air provided by a bypass as described for example in the above-identied earlier patent applications.

The carburetor of FIG. 1 can be essentially the same as standard carburetors and can havean accelerator pump to improve the accelerating characteristics of the engine, although this adds measurably to the degree of undesired emission discharged in the exhaust. The throttle-closing check can also be arranged to operate with liquid taken from the fuel bowl of the carburetor, as for example in the carburetor illustrated in Fig. 149 on page 67 of the 1963 Ford Galaxie and 1962-63 Mercury Monterey Shop Manual Supplement, copyright 1962 by the Ford Motor Company, Dearborn, Michigan.

The rate at which the mixture flow reduction takes place can be adjusted by varying the viscosity of the hydra-ulic check medium, the size of the restriction through which the medium is forced, the linkage that actuates the checking piston, and the strength of the compression or return spring 26. The last two variables can also be arranged to vary the uniformity of the rate of mixture flow reduction. A uniformathrottle closure rate is obtained during checking by keeping the force on the checking piston uniform. To this end the -lever arm of arm32 can Ibe made substantially unvarying through the checking travel, and the actuating force of the throttle return spring (not shown) can be made more uniform as by changing Iits component in the direction of motion. The tendency of this lever arm to increase in length with the retraction of arm 36 from the fully closed position illustrated in FIG. 1, for example, can be compensated for by rounding the nose 30 so that the point of tangency of the arm on the nose remains on the same spot of the arm although the point travels along the surface of the nose. This compensation is provided by the arrangement of FIG. 1. This arrangement also shifts the component of the throttle-closing force so as to compensate at least partially for the normal drop in the closing force applied by the throttle-closing spring as the throttle closes.

The throttle-checking of FIG. 1 can also be connected so that it is disabled at low speeds, as described in application Serial No. 301,249. Such disabling can respond to low eng-ine speeds, or low speeds of an automobile powered by the engine.

The minimum mixture velocity in the intake manifold of the induction system of FIG. 1 is higher than that of standard engines used in automobiles, even higher than those that are normally yoperated with a relatively fast or more powerful idle to make sure that power-consuming accessories such as air conditioner pumps do not cause stalling. In general, the air flow increase of the construction of FIG. 1 is larger for engines with fewer accessories of the foregoing power-consuming kind. In the case of an engine with an all-mechanical transmission the air ilow increase is preferably about 40 to 60%, whereas an engine with an automatic transmission can have an increase of only about 20 to 45% for best results. In either type of situation the increased flow rate is not suflicient to give smooth operation with the lean mixtures that are preferred, unless the intake mixture temperature is in the range of about 140 to about 185 F., preferably 160 to 185 F., at light load. Such heating Ais readily obtained by suitable adjustment of the flow of exhaust gases onto a heating surface in good heat-transfer relation with the intake manifold, preferably just before it branches. The heating of the mixture can be effected in other Ways, but it is desirably controlled in the cony ventional manner so that increases in under-hood temperatures or the like will reduce the amount of exhaust or other heating, thereby keeping the mixture temperature from getting too high when the engine is hot. It is also helpful to interconnect the throttle with the heat control so that opening the throttle to the widest will completely close off the flow of exhaust through the heating path,

thereby increasing the volumetric efficiency of the engine at maximum power operation. An extra linkage 60 as shown in FIG. 1 is connected to throttle control 36 for this purpose.

Reduction tof undesirable emission from the exhaust under deceleration conditions is so sharp, even when used in automobiles having manual, that is all-mechani- `cal transmissions, that the improvement thereby obtained cannot be attained with fuel-cut-oif devices. Such devices may, for example, stop all ow of fuel into the carburetor throttle when decelerating from high speed, but because combustion is also stopped the fuel in the mixture in the manifold before cut-off continues to pass through the engine and produces a relatively high level of undesirable emission. The construction of FIG. 1 accordingly does not need any fuel cut-olic arrangement, and thus avoids some complexity.

Also because of the relatively high minimum air flow velocity in the induction system, the throttle-checking described above Iis not very critical in nature. So long as it begins to take eiect when the air ow rate drops to about $40 pound per hour per cubic inch displacement and causes further reduction to proceed at about 5 to 10% per second, the desired results are obtained. Only about 5 to 10 seconds of checking is thus needed.

The foregoing induction and ignition combinations can also be used in dual intake manifold systems such as those describe-d in the vabove-listed prior applications. A more simplified yet highly effective dual intake manifold assembly is illustrated in FIG. 3. The assembly of FIG. 3 has two carburetor barrels 132, 232 each terminating at its lower end inra flanged connector 71, 72

for mounting `against intake manifold lopenings 61, 62 respectively. At their upper ends these barrels have choke valves 140, 240 which can be operated in the conventional manner. Barrel 132 has a throttle valve 134 connected forl rotation by shaft 104 which carries 4an arm 106 located outside the barrel. Throttle valve 134 is arranged to seat directly against the walls of barrel 132 when the throttle of the induction system is to be closed, so that no significant ow takes place between this valve and the walls of its barrel.

The iiow of idle air is arranged to take place through a hole 148, preferably round, punched or drilled through valve 134, or by an external by-pass that connects the barrel above the throttle valve with the barrel below the throttle valve. Idle air flow can also be provided by a combination of hole 148 and external by-pass. As explained above, this arrangement shifts the idle air flow away from the lenticular or crescent-shaped gaps usually provided between the ends of the throttle valve and the walls of the barrel. Such crescent-shaped gaps are subject to so much variation due to accumulation of deposits and/ or wear that continual maintenance is needed to keep in proper adjustment the conventional idle systems that use such gaps.

Barrel 132 can have conventional gasoline supply arrangements for idle fuel, high speed fuel, and high power fuel, and these arrangements are not illustrated. Reference is made to application Serial No. 301,249 for effective supply arrangements, particularly one in which a main fuel supply jet has an air bleed thermostatically modulated to enrich the main jet mixture when the ambient temperature is very low.

Carburetion barrel 232 is generally similar to barrel 132 except that it is shown somewhat larger in crosssectional area. Only a supply of high power fuel is needed for barrel 232 so that a throttle valve 234 in this barrel can close against its barrel walls without any provision for a by-pass. Throttle valve 234 is controlled by an arm 206 arranged for actuation when throttle 134 is wide open and more power is called for.

Manipulation of the throttles is effected by a rod 92, one end 94 of which is connected to the throttle control such as the accelerator pedal of an automobile in which the engine is mounted. The rod 92 passes loosely through two bosses 96, 98, each of which in turn has a projecting stud 88 that is pivotally received in their respective arms 106, 206. Rod 92 also has two collars 85, 86 xed in position as shown. A compression spring 83 between collar 85 and boss 96 enables movement of rod 92 toward the left as seen in FIG. 3, to rotate arm 106 around shaft 104. A washer 81 can be inserted between the spring 33 and boss 96. As the rod 92 is moved more and more to the left, its collar 86 eventually engages boss 98 when throttle 134 is open wide. Further movement of rod 92 to the left will then open throttle 234 while spring 83 compresses to allow the rod to move through boss 96 without disturbing the open position of throttle 134.

A mechanical bias such as tension spring 84 urges throttle 234 toward fully closed position, and a separate bias such as spring S7 can be used to urge throttle 134 closed. Spring 84 can be made more powerful than the bias for the throttle 134, so that the operator can tell when he is operating the throttle pedal far enough to open the large induction system. The degree of force required to open the large throttle can be made such that the operator cannot readily maintain it open for a long period `of time so that the engine is more apt to be operated on the small induction system alone.

The carburetion assembly of FIG. 3 also includes a small pump 210 to momentarily supply to secondary barrel 232 a small amount of additional fuel each time the secondary barrel is brought into use. Pump 210 can have a conventional accelerator pump construction with an intake 219 opening into the liquid in carburetor 8 bowl 150, and a discharge line 245 running into throat 232. A ball check 220 in the intake and another check 221 in the discharge make sure the liquid is pumped properly and yet not permitted to be sucked into throat 232 when the pump is not operated.

Pump 210 has a diaphragm 216 secured to a piston 231 carried by a piston rod 230 slidably tted through the wall of the pump. The slidable tting can also act as a vent for the chamber around the piston rod, and a spring 238 in the cylinder urges the piston outwardly to bring the pump into position for a pumping stroke.

When the control operates to effect the opening of the manifold of larger cross-section, rod 92 engages piston 230 and causes it to compress its spring 233, squirting a single charge of supplementary fuel into throat 232. Pump 210 will continue to operate as an acceleration pump for the larger manifold. When there is a return to the use of only the smaller manifold, rod 92 is disengaged from piston rod 230, permitting the piston to be pushed out by its spring 238. This draws replenishing fuel from the carburetor bowl through intake 219, and the pump is thus prepared for the next pumping stroke.

Pump 210 can be arranged to operate essentially only when shift-over takes place to the larger induction system. This is readily accomplished by arranging for the pump to have an extremely short stroke that is completed when the large throttle 234 is barely opened. Further manipulation of that throttle will then not pump any more fuel so that pump 210 will not operate as an acceleration pump under those conditions and will merely be a shift-over pump.

A single charge of about 1/2 milliliter of supplementary fuel per cubic inches of engine displacement, made when the manifold of larger cross-section is brought into use, has been found to make particularly smooth the change-over in engine operation, even when the engine is under heavy load, without detracting significantly from the eiciency of the engine and without significantly increasing its emission of unburnt and partially burnt fuel as well as of carbon monoxide. However, as much as l milliliter can be used per 100 cubic inches of engine displacement with very good results, and as little as 1/s milliliter per 100 cubic inches will give detectable irnprovement, although no extra fuel whatever is needed to make the engine perform adequately.

It is not necessary to have a fixed quantity of supplementary fuel delivered by pump 210 each time the large throttle is opened. The quantity can be varied as by means of a temperature responsive control that inserts a wedge-shaped spacer between the piston rod 230 and control rod 92.

The engine operation shows no detectable roughness when the large manifold is switched off by closing of the large throttle valve. No accelerator pump is needed for the small carburetor inasmuch as the small induction system has a cross-sectional area less than 5A; square inch per hundred cubic inches displacement of total engine displacement, and the mixture ow is accordingly very rapid at idle even without the higher air flow of the construction of FIG. l.

Throttle valve 134 is also arranged so that it cannot be abruptly moved into its fully closed position. For this purpose a stop arm secured to the throttle valve 134 cooperates with a dash-pot 182 having a plunger 184 positioned for engagement by the stop arm as it approaches the fully closed position. The plunger 184 is secured to a diaphragm 186 that defines an air cushion zone 188 vented by a small opening 190. A spring 192 inside the dash-pot urges the plunger outwardly to engage the stop arm, but is not strong enough to overcome the throttle-closing forces. The throttle will then move to its fully closed position only as fast as the air cushion 188 is permitted to vent through opening 190. A few seconds is thus required for the last few degrees of throttle closure.

9 The return of the plunger 184 by its spring 192 when the throttle is opened, can be made much more rapid and is preferably completed in about a second or less so as to be prepared for another deceleration when it will introduce another appropriate delay. This helps assure a minimum of undesired emission products.

FIG. 3 `shows opening 190 to be incorporated in a check valve disc 191 biased as by a spring against a stop that restricts outflow of air to that opening but permits inflow of air around the disc. This will provide the more rapid return of plunger 184.

Notwithstanding the relatively high speed with which a fuel-air mixture moves through the primary manifold even at idle, this manifold can still be provided with heat- King sufficient to bring the mixture it conducts to a Wet bulb temperature of between about 140` .and 165 F. measured onder light load at a branching point in the manifold. The temperature of the mixture in the primary manifold can be as high as 185 F. but the lower range is preferred to give the smoothest operation combined with rapid warm-up.

It has generally been considered that Iheating requirements become less and less acute as the velocity of the fue-l-air mixture increases. This is based on the observation that high velocities in the intake manifold so speed up the movement of the vaporized fuel droplets and films that branching tends to take place more and more uniformly.

Pursuant to the present invention, however, the mixture in the primary manifold is made quite lean at light load and at idle, and this leanness seems to entirely offset the equalizing effect of Ithe higher mixture velocity.

The secondary manifold requires substantial heating, particularly to provide quick warm-up. It has been discovered that heating the internal surface of the secondary manifold so that it reaches a temperature from about 300 to 450 F. when the engine is opera-ted from a cold start for three minutes under lowspeed cruise conditions, e.g. 20 miles per hour, is readily accomplished and is highly desirable. Such heating enables very effective and smooth operation when the secondary throttle is opened three minutes after a cold start with very little or no choking, even at ambient temperatures of F. As indicated above, this heating will warm the stagnant contents in the secondary manifold to an equilibrium temperature generally in the range of from about 170 to 225 F.

Although a pneumatic throttle check is illustrated in FIG. 3, hydraulic checks of the kinds referred to above can be substituted.

FIGS. 4 and 8 show a dual inta-ke manifold assembly applied to a four cylinder in-line overhead valve engine in which the cylinder head is indicated at 410. One side of the head has a series of openings 421, 422, 423, 424, 425, 426 and 427 leading to or acting as ports for the intake and exhaust valves in the individual cylinders. Openings 421 and 427 are exhaust ports for the end cylinders respectively, and `opening 424 is an enlarged exhaust port which is common to the two center cylinders. An exhaust manifold 430 has flanged connections 431, 434 and 437 secured as by the usual manifold mounting bolts to the cylinder head 410 to collect the exhaust from all four cylinders .and deliver it to flanged exhaust pipe discharge 439.

Two intake manifolds 448, 450 are secured to the head 410. Manifold 450l has a set of flanged connections 452, 453, 455 and 456 arranged to |be connected with the upper portions of intake openings 422, 423, 425 and 426 respectively. The lower or remaining portions of these head openings are connected by extensions 442, 443, 445 and 446 to the main branches 448, 449 `of intake manifold From FIG. 8 it will be noted that intake head opening 422 is divided by a partition 412 into an upper intake port 414 and a lower intake port 416. Connection 452 of the intake manifold 450 leads directly into upper port 414, and connection 442 of int-ake manifold 440 leads directly into lower intake port 416. Both ports 414 and 416 merge into .a comm-on intake chamber 418 adjacent t-he intake valve seat 419.

Between branches 448, 449 of intake manifold 440 in FIG. 4, there is a mounting connection 461 for a fuel-air supply barrel of a carburetor. In the same way another mounting connection 462 is provided, preferably in the central portion 459 of intake manifold 450 for another barrel of a carburetor.

The central portions of both manifolds 440, 450` are shown as located directly over the central portion of exhaust manifold 430` so .as to have the exhaust manifold provide the heating for the intake manifolds. For greater effectiveness the central portion 459 of manifold 450 is placed at a lower level than its head openings 452, 453, 455, 456 so as to bring it closer to the exhaust manifold even though openings 452, 453, 455, 456 are some distance .above the exhaust manifold. Alternatively the exhaust manifold can be so shaped that its upper surface is elevated where it runs lunder manifold 450 to bring that surface into good heating relation with that manifold.

The two carburetion barrels connected to mounting openings 461, 462 of the intake manifolds can be the two barrels of the carburetion assembly described in FIG. 3 or any one of the parent applications Serial No. 171,856, Serial No. 301,249 and Serial No. 314,814.

FIG. 5 shows a dual intake manifold modification suitable for use with a V-8 engine in accordance with the present invention. In this construction there is a pair of primary manifolds 548, 549, each identical in configuration. Manifold 540 has branches 541, 542, 543, 544 that run respectively t-o the intake ports of the outer two cylinders of the second bank .and the inner two cylinders of the first bank. Similarly, manifold 549 has branches 545, 546, 547 and 548 for connecting respectively to the intake ports of the inner two cylinders of the second bank and of the outer two cylinders of the first bank.

Each primary manifold has an intake opening 530, 539 for connection to separate carburetor barrels of a dual barrel primary carburetor, each lbarrel of which can be identical to barrel 132 of the construction of FIG. 3.

Directly under and extending beyond both ends of the primary intake manif-olds is a pair of secondary manifolds 550 ,and 559. Manifold 550 has branches 551, 552, 553 and 554 running to the intake manifolds of the inner cylinders of the first bank and of the outer cylinders of the second bank respectively. Manifold 559 conversely has branches 555, 556, 557 and 55S, for the intake ports of the :inner cylinders of the second bank and lthe outer cylinders of the rst bank, respectively. The Ibranches of the outer cylinders at the adjacent ends of the two banks cross over each other, and the cross-overs can be of either hand. That is, branch 554 can cross over the top of branch 558 or branch 558 can cross over the top of branch 554. The s-ame applies to branches 553 and 557.

iInstead of having the carburetor connections of the secondary manifolds in the central portions of the manifolds, they Iare shown at 561, 562 in the portions of the secondary manifolds that extend beyond the ends of the primary manifolds. On each site 561, 562, connections are provided in a dual barrel arrangement and each barrel at each of these locations can be identical to barrel 232 of the construction of FIG. 3. Location 561 can have one of its barrel intakes 571 opening into manifold 55E) adjacent the location where branches 551, 553 join. Similarly, barrel intake 572 at location 561 opens into secondary manifold 559 adjacent the location where 1 1 branches 556, 557 join. At location 562 one of the barrel intakes 581 similarly opens into branches 552 and 554 of manifold 550 while barrel intake 582 leads to branches 555 and 558 of manifold 559.

A heating jacket 52@ is shown as surrounding the entire central portions of primary manifolds 540 and 549 as well as the central portions of secondary manifolds 55@ and 559, and provides the heating referred to above. The jacket is conveniently connected as by ducts 521, 522 to exhaust ldischarge openings that are conventionally provided in each bank of the cylinders.

The ends lof the primary manifold branches in the construction of FIG. 5 are smaller in diameter than the ends of the secondary manifold branches and the primary branch ends are shown as penetrating through the walls of the secondary branch ends so that the primary ends are brought down to a level below that of the secondary ends internally of the secondary branches. The effective lengths of the primary fuel supply paths are thereby diminished, as compared with running the ends around the secondary manifold 'branches to get below them.

Three dual barrel carbuertors can be connected to the barrel intake openings of the manifold assembly of FIG. 5. A primary carbuertor of this type supplies the primary manifold intake openings 530, 539, and two secondary oarburetors of this type, one each at locations 561, 562 supply the secondary manifold combination.

In accordance with the present invention other modifications of intake manifolds are effectively used with V-8 type engines. For example, the primary manifolds 540, 549 in FIG. 5 can be combined into a single manifold fed by a single barrel of a carburetor having eight branches, one for each cylinder. Another modification is the elimination of the central portions of secondary manifolds 550, 559 from the construction of FIG. 5 and leaving the two carburetor barrel intake locations S61, 562 disconnected from each other. At each such location, according to this modification, each carburetor barrel intake opening supplies only two cylinders. A further variation is to have at each location 561, 562 only a single carburetor barrel intake opening leading to the four cylinders at that end of the engine. In this single barrel variation the single barrels at each end of the engine can either be disconnected from each other, or they can be united through an equalizing conduit as in the construction of FIG. 5.

The carburetor barrel intake openings at locations 561, 562 can also be moved into positions adjacent the carburetor barrel intake openings 530, 539 of the primary manifolds so that a unitary carburetor with an appropriate number of barrels can be mounted in place to supply all the manifolds. This combination is more readily eected when the equalizing conduits for the secondary manifolds are eliminated. In any event, by such bringing together of the various carburetor barrel intake openings a V-8 engine can be equipped with just one triple barrel carburetor having one primary barrel for the primary manifold and two secondary barrels, one for each barrel intake opening of the secondary manifold combination.

FIG. 6 illustrates a manifold assembly with a triple carburetor barrel intake. The primary manifold 640 is fed by a central barrel intake 630 and two secondary manifolds 659, 659 have barrel intakes 661, 662, respectively, on either side of intake 630. To allow closer juxtaposition the secondary manifolds are each made about twice as high as they are wide, and they each branch into upper and lower halves that extend out to the respective cylinders. The upper half 611 of the manifold 650 terminates in branches 657, 658, whereas the lower half ends in branches 651, 652. A similar construction is shown for secondary manifold 659.

There is no communication between the two secondary manifolds except by way of the branches of the primary manifold 640. These branches can be at a level low engine such as that illustrated in FG. 2.

enough to `directly penetrate into the corresponding ends of the secondary manifold branches.

To make the mixture flow paths more or less equal in length for each cylinder, the lower halves of the secondary manifold can be arranged below the level of the cylinder intake ports so that the inner branches 651, 652, for instance, extend upwardly before they reach the ports. This added upward distance plus the added distance the mixture travels to reach the lower manifold half from intake 661, can be made to equal the total travel distance through the upper manifold half.

The intake openings 661, 662, are also offset to correspond to the offset orientation of the intake ports in a V-8 engine, for example, so that these openings are in the longitudinally central portions of their respective manifolds.

The small manifold can have its branches lowered so as to be below the heating jacket 624i shown as enveloping the central portion of both manifolds. This reduces the heating of the primary manifold with respect to the secondary.

It is not necessary to have the primary and secondary manifold branch ends adjacent each other at each cylinder. FIG. 7 shows an effective intake arrangement for an In the construction of FIG. 7 the intake valve seat 719 leads to an intake port or chamber 718 that divides into two branches extending out different sides of the head. A primary branch 716 is arranged for connection to a primary intake manifold on one side of the head, and a secondary branch 714 is arranged for connection to a secondary manifold on the other side of the head. Such branched intake openings can be arranged in heads even of the liquid-cooled overhead valve type without significantly reducing the heat-transfer characteristics of cooling jackets and the like.

It is desirable to have the fuel-air mixture conduit from the pri-mary intake manifold terminate at a location that averages about one-third to one inch from the intake valve seat. If the distance that separates the primary conduit termination from the intake valve seat is made materially larger than one inch, the liquid components of the mixture tend to be excessively deposited on the walls of the relatively large open end of the conduit for the secondary fuel-air mixture. On the other hand, making the average distance between the valve seat and the termin-ation of the primary fuel-air con-duit significantly smaller than lone-thi-rd inch makes the construction awkward to manufacture.

The average distance referred to is the distance between the valve seat and the avera-ge level of the primary fuel-air mixture conduit opening, measured along a line connecting that average level with the nearest portion of the valve seat. For primary fuel-air mixture conduits of circular, square, eliptical Vor similarly symmetrical crosssections, the average level is the level of the center of such cross-sections.

The flow of unvaporized portions of the fuel-air mixture from the termination of the primary conduit of the present invention into the valve port is better when such flow is downhill than when it is uphill. Accordingly, overhead valve engines in which the intake valve seats are below the valve port or chamber from which they are supplied, are preferred. A similar benefit is Iobtained with L-head type engines but in this arrangement the engine would be turned upside down, that is with its crank shaft up and its head down, and such an arrangement is not ordinarily desirable in automobiles because -of the awkwardness in transmitting the power from the relatively high crank shaft to the relatively low location of the driving axles.

There seems to be no real limit to the minimum size of the primary manifolds. Even if its internal opening is pencil-thin, it will supply an adequate amount of fuel to operate high-displacement engines at fair power out- 13 puts. Accordingly while the primary manifold is conveniently made with an internal cross-sectional area onefifth that of the secondary manifolds, it can be made substantially smaller than one-fifth, as for example onesixth or one-seventh, particularly if maintenance provisions permit the removal of dep-osits that tend to form within the manifolds.

FIG. 9 illustrates the exhaust recirculation aspects of the present invention. Here a carburetor 910 which may be of the dual induction type, has a primary barrel 932 opening into engine intake manifold 949 and controlled by throttle valve 934. Shaft 904 pivotally holds the throttle valve 934 and is extended to 4hold an exhaust recirculation valve in an exhaust recirculation line 942 that opens intake manifold 940 to the engi-ne exhaust. The valves 934 and 944 are arranged to be operated simultaneously as by arm 906 fixed to shaft 904 and controlled by an actuator rod 994 as in the construction of FIG. 3, for example.

The simultaneous action of the throttle and recirculation valves provides a very effective and practical exhaust recirculation control. At idle it is better to have no exhaustrecirculation, whereas at other throttle positions as much as 15% or so of exhaust recirculation can be handled to achieve sharp decreases in emission of nitrogen oxides. By having recirculation conduit 942 with a cross-sectional area about 15 of that of the carburetor throat 932, such highly effective recirculation control is very simply attained by the construction of FIG. 9. A venturi 955 can be inserted in the recirculation conduit to even more closely proportion the recirculation to the flow through the principal venturi 945 in throat 932.

For maximum power output, it is desirable to shut off the exhaust recirculation. To this end the construction lof FIG. 9 includes a further control valve 964 that is normally open but is automatically closed when the main throttle is wide open. An arm 926 is shown as operating valve 964 and Imounted for engagement by the control rod 994 when in the wide-open throttle position. By shortening arm 926 it can be made to actuate valve 964 from fully open to fully closed as the contr-ol rod moves the main throttle valve through only the last few degrees of opening. Alternatively the valve 964 can be arranged to begin to close only after the main throttle is wi-de open, as by having a resilient or overtravel connection between the main throttle and the -operating rod 994.

The foregoing arrangement can be used with an engine having a single intake manifold, and will give very good results with no attention on the part of the operator. For engines with dual induction systems as in FIG. 3, the manifold`940 can be the primary or low-power manifold and the secondary or high-power manifold can be used without an yadditional'exhaust recirculation supply to it. The opening of the throttles in both primary and secondary manifolds will cause at least 80% or more of the combustion mixture to be carried by the secondary manifold so that the exhaust recirculation to the primary manifold is of less significance and the auxiliary recirculation valve 964 can be eliminated without greatly detracting from maximum power output. Where 90% or more of the combustion mixture is delivered through the secondary manifold, the power limitation resulting from elimination of valve 964 is insignificant.

The combination of FIG. 9 can be used with the principal throttle valve 934 arranged to completely close against the walls of carburetor throat 932 for idle operation. In such an arrangement a by-pass as indicated at 948 can be used so that valves 934 and 944 can be parallel, that is positioned in oo-planar arrangement. On the other hand, principal throttle valve 934 can be provided with a stop that keeps it from engaging the Walls of throat 932 at idle, as in the construction of FIG. 1. In that event it is preferred to have exhaust control valve 944 tilted somewhat with respect to valve 934 t-o permit exhaust control valve 944 to completely close when valve 934 is in idle position. Only a few degrees of tilting is needed and this has no significant effect on the exhaust recirculati-on. The slight reduction in the resulting recirculation proportion can -be compensated if desired by suitably enlarging `the cross-sectional area of the recirculation duct as compared wit-h that of the intake manifold.

By combining the features of the apparatus of FIG. 1 with that of FIG. 9, there is obtained an engine strikingly superior in its exhaust emissi-on characteristics. However, the features of the construction of FIG. 9 can be used by themselves as well as with those of the dual induction system of FIG. 3 or those of the above-referred to earlier patent applications.

Where the increased idle air flow deceleration system of FIGS. l and 2 is not used, it is preferred to incorporate a fuel cut-off deceleration system as described, for example, in applications Serial Nos. 301,249 and 314,814. A modified form of such fuel cut-off arrangement is illustrated in FIG. 10 based on the prirnry fuel carburetor constructions of FIG. 4 in application Serial No. 314,814.

As described in the last-mentioned application, the carburetor of FIG. l0 has a throat 132 connected to manifold 321, and with a venturi 336. Fuel is supplied from an inlet tube 354 to a float chamber 352 and from there through the combination of a main jet orice 358, a supplementary jet orifice 331, and a power jet orifice 384. An idle fuel take-off 368 branches from the main jet passageway and leads to idle discharge port 341 controlled by adjusting screw 378, as well as to idle transfer port 372. Throttle plate 134 closes against the wall of throat 132 and when so closed shuts off all passage of air and fuel except for idle fuel and an idle air bypass 346.

F-low of fuel through the main jet orifice is also controlled by a cut-off valve 162 which is operated by the automatic control 351 connected through conduit 302 to the interior of manifold 321. A branch 300 of that conduit is also connected to directly actuate a valve 396 that controls the power fuel jet. This jet is modulated by a temperature-controlled air bleed 383, and a similar modulation can be applied to the main or supplementary jets in place of or in addition to the power jet. The modulation action as well as the operation of the other carburetor features are more fully described in application Serial No. 314,814 and that description is hereby incorporated herein as though fully set forth.

Control 351 controls the application of suction from a suction source 142 to a conduit 143 that operates cutoff valve 162. To this end lines 142, 143 are connected through a slide valve 330 with a hollow interior in which is slidably fitted a valve block 332 having a recess 340 that spans the distance between the locations where lines 142, 143 open into the valve.

Block 332 is actuated by a pneumatic cylinder that has a piston 171 fitted to be moved to the left, as seen in FIG. 10, to compress biasing spring 168 when the vacuum in line 302 reaches a magnitude at which fuel 'cut-off is to be effected. A piston rod 166 carried by piston 171 is shown as penetrating into the slide valve 330 and passing loosely through a passageway 331 in the block 332. Collars 311, 312 are carried by the piston rod and can be fixed or adjustably located on the rod to engage and move the slide block with a lost motion gap indicated by the spacing 314.

Asillustrated, cut-off valve 162 is biased towards cutoff position by spring 166, and the flow of fuel is cut offwhenever suction is not applied to line 143. The development of relatively high vacuum in manifold line 302 by an abrupt deceleration of an yautomobile operated by an engine having the carburetor of FIG. l0, moves piston 171 to the left carrying slide block 332 with it into the illustrated position. This disconnects the suction from line 143 and fuel is cutoff.

As deceleration proceeds, the vacuum in line 302 diminishes gradually and piston 171 will slowly be forced to the right under the inuence of its biasing spring 168. Spacing 314 permits the piston to move a substantial distance before it begins to move valve block 332 to the right to apply suction to line 143 and open the cut-off valve 162. Biasing spring 168 is preferably arranged so that the fuel flow is not restored until the deceleration proceeds to the desired extent. By the above arrangement the lost motion of spacing 314 provides a control hysteresis which is particularly preferred as compared with the frictional type of hysteresis disclosed in application Serial No. 301,249. The lost motion is subject to substantially no variation as a result of temperature changes and the like, and can be accurately set in production.

Decelerations of automobiles should produce fuel cutoff only when the deceleration is from relatively high speed, over miles an hour, in order to keep the exhaust emission low, and the manifold vacuum changes during such decelerations are somewhat critical. For example, decelerations from about 30 miles an hour can increase the manifold vacuum to about 22 inches of mercury so that the control 351 is preferably set to cause cut-olf when the manifold vacuum reaches 221/2 inches. During deceleration the manifold vacuum will drop to about 211/2 inches when the vehicle speed comes down to a satisfactory low level such as 18 miles per hour, and control 351 is accordingly also arranged so that at this level of vacuum the biasing spring 168 will push piston 171 to the right sumciently far to cause restoration of fuel ow. Before this level of vacuum is reached, biasing spring 168 can push piston 171 a distance corresponding to the lost motion.

Once the flow of fue-l is restored the lost motion will keep it from being cut off again until the manifold vacuum reaches the 221/2 inch level. Since this level is not reached when the automobile is operated in any way other than deceleration from the appropriate high speed, there is no interference with the operation of the automobile. The cutting off of fuel will also terminate and fuel flow will be restored whenever there is a power demand on the engine, as by opening of the carburetor throttle. Such opening sharply reduces the manifold vacuum to a 'level well below 211/2 inches so that piston 171 is rapidly moved all the way over to the right by its biasing spring. An automobile equipped with a relatively large size engine can be operated in the above manner by having the fuel cutoff respond to deceleration from at least about 1200 r.p.m. with the cutoic terminating when the engine speed falls below about 850 r.p.m.

FIG. 10 also shows control 351 connected to supply a small amount of auxiliary fuel when a fuel cut-off is terminated. This additional fuel is provided by pump 110 operated by a separate suction line 141 that is also under the control of slide valve 330. To this end valve block 332 is arranged as in application Serial No. 314,814 to connect suction source 142 with line 141 when the suction source is disconnected from line 143, and vice versa. The pumping of the fuel is more fully described in the lastmentioned application and takes place through a pump outlet 349 that opens into air bypass 346, preferably in a relatively wide portion 353 of the bypass with the stream of pumped fuel 350 directed at a narrowed portion of the bypass.

The construction of FllG. 11 has a three-carburetorbarrel intake feeding a single induction manifold of a V-8 type engine. This induction system has a common passageway 800 branching to all cylinders, and a mu-ltiple carburetion assembly connected to said passageway, said assembly including one carburetor 811 having a venturi 821 with a cross-sectional area between about 5 and 30% that of the passageway. Four of the manifold branches or runners open at 801, 802, 8d3, 804 in one wall 806 of the passageway, the remaining four opening in a similar manner in the opposite Wall and are not seen in the figure.

Two additional carburetors 812, 813 are connected to the passageway 800, and these carburetors can in general resemble the secondary carburetor system of FIG. 3. The secondary carburetors do not require an idle fuel supply, idling of the engine being accomplished with the fuel mixture supplied by the primary carburetor 811. The venturi 821 of the primary carburetor has a cross-sectional area about 5 to 25% of the total cross-sectional area of the primary and secondary fuel mixture supplies. The venturis 822, 823 of the secondary carburetors can, for example, each have a cross-sectional area twice that of the primary venturi.

An engine according to FIG. 11 will surprisingly enough operate very satisfactorily under part throttle conditions with a fuel mixture leaner than heretofore considered practical. Thus in a standard 1964 model Pontiac V-8 in which the standard two-barrel carburetor intake manifold has had its common wall, .a partition 1%@ inch deep by 1% inch long known as the riser partition removed and the carburetor has been replaced with 4one that has a venturi 0.88 inch in diameter and adjusted to supply a mixture with a selectable ratio, very good operation was obtained with air-to-fuel weight ratios as high as 15:1 and higher. In this configuration the venturi had a cross-sectional area about 11% of that of the cornmon passageway. Misring did not begin until the ratio reached about 17.5: 1, and the engine was judged suitable for general part throttle duty with a ratio of up to 16: 1.

The removing of the riser partition from the standard two-barrel carburetor intake manifold converted it to one in which a common passageway branched to all cylinders. Before the riser partition was removed the same engine operating with the normal two low-speed barrels of a standard four-barrel carburetor recommended for use with it would not operate smoothly at part throttle with mixtures leaner than about 14: 1.

The small venturi 821 of the carburetor 811 is the only one used at part throttle operation, that is when the engine delivers a-ll the power demanded and the throttle of carburetor 811 is not open wide. Apparently the small size of this venturi provides a very uniform part-throttle mixture which distributes itself uniformly to the cylinders via a single common passageway, particularly in a V-8 engine where the distribution is otherwise very poor. Although the common passageway is large enough to adequately carry the much more concentrated fuel mixtures needed for operation at maximum power, and the part throttle fuel mixtures are much more rareed, they still travel through the common manifold at a rate fast enough to achieve good distribution. It is the lack of good distribution in the conventional V-8 engines which leads to mixture enrichment for the purpose of providing adequate performance from the cylinder receiving the leanest mixture as a result of the poor distribution.

The small venturi carburetor is the only one used at idle, and in combination with the single common manifold provides idle operation which is smoother than with the standard two-barrel carburetor and much simpler to adjust. Idling can accordingly be accomplished with the engine of FIG. 11, using idle mixtures of about 14.5 :1. The idle adjustment of two carburetor barrels each supplying half the cylinders as in the standard engine, is almost impossible to accomplish properly without a set of expensive instruments, whereas the accurate adjustment of a single idle barrel as in the construction of FIG. 11, is readily carried out with only a tachometer.

In the part throttle operation of the engine of FIG. 11, generally at speeds of at least 1000 r.p.m., the automobile can be driven at a constant speed as much as 75 miles per hour, so that most of the engine operation is under such conditions. The emission of undesired products such as CO and unburned or partially burned hydrocarbons is sharply reduced by the lean mixture operation under those conditions, and fuel economy is correspondingly improved. In the standard engine described above hydroother hand the engine of FIG. 1l performed very smoothly at part throttle with a mixture ratio of 16:1 and a hydrocarbon emission of only 112 parts per million. The comparable fuel consumption rates at 1200 r.p.m. and horsepower output were 11.7 pounds per hour for the standard engine as against 10.6 pounds per hour with the engine of FIG. 11.

The heating of the induction mixture in the construction of FIG. 11 can also be to between 140 and 185 F, and that ligure illustrates a ribbed hot spot 830 in the common passageway 800 and in good heat exchange relation with a duct 840 that carries exhaust gases. The hot spot is preferably directly under the small carburetor.

The larger carburetors 812, 813 are brought into use under high power demand as for example when the throttle of carburetor 811 is wide open and more power is needed. The controls for such purpose can be of the type illustrated in FIG. 3, although there is no need for extra pumping of fuel when the large carburetors are opened. Instead of having two large carburetors 812, 812, the high power mixture can be supplied by one large carburetor or by three or more carburetors, or even by fuel injection combined with additional air supply means into the manifold or into the intake ports or into the cylinders themselves. The large carburetons need not be arranged downstream from the small carburetor, but can be connected transversely with respect to it. A conventional acceleration pump does help the acceleration of the engine of FIG. 11.

In the foregoing combination of a 0.88 inch venturi with a modified Pontiac intake manifold, the venturi provided a cross-sectional area about 0.10 of the total venturi cross-sectional area used for maximum power in the standard engine. Also this was 0.11 of the crosssectional area of the common passageway in the manifold and about 0.16 square inch per 100 cubic inches of piston displacement. This latter proportion can vary from about 0.1 to about 0.2 square inch per 100 cubic inches of piston displacement. Inasmuch as about 70 horsepower can be obtained from each 100 :cubic inches of displacement, this corresponds to 0.1 to 0.2 square inch of venturi cross-section for every 70 horsepower of maximum engine output. Engines with a relatively large number of cylinders such as 8cylinder engines or engines whose speed is limited to relatively low values such as large truck, bus orv industrial engines will normally operate best near the low limit of this range while other engines can make effective use of venturi sizes nearer the high limit.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed:

1. A gasoline engine h aving (a) a mixture intake system connected to provide a fuel-air mixture Which underh` non-choking conditions has an air-to-fuel weight ratio not lower than about 14 except under high torque operation and to maintain a tiow of fuel throughout all decelerations, (b) a throttle-closing check connected to limit the Y reduction of the rate of mixture flow to the intake system to about 5-10% per second when the throttle control is abruptly closed during high speed operation and the air flow rate reaches about 0.4 pound per hour per cubic inch displacement, (c) an idle air flow rate about to 60% greater than the minimum for idling at no road load with 6 ignition advance before top center, and (d) ignition timing mechanism connected to retard the ignition to about 3 to 6 after top dead center at idle,

said mechanism having a vacuum advance system that provides essentially no vacuum advance when the throttle is in idle position.

2. The combination of claim 1 in which the engine has a plurality of cylinders and the intake system has an unbypassed manifold connected to provide a mixture having a temperature of from about 160 to about 185 F. at light load.

3. The combination of claim 1 in which the throttleclosing check has liquid dash-pot check mechanism.

4. The combination of claim 1 in which the engine has a plurality of cylinders and the intake system has a'lowpower manifold bypassed by a high-power manifold, the low-power manifold being connected to provide a mixture having a temperature of from about to 165 F. at light load.

5. The combination of claim 2 in which the intake system includes mechanism -connected to reduce the mixture temperature at maximum torque condition.

6. A method for keeping a gasoline engine firing during rapid deceleration from relatively high speeds while maintaining good engine braking, which method comprises checking the rate of throttle closure so that the reduction of the rate of mixture flow to the intake systern is about 5 to 10% per second when the air flow rate reaches about 0.4 pound per hour per cubic inch displacement, limiting the shut-down of induction mixture flow to an air intake about 20 to 60% higher than the minimum for idling under no road load -with 6 ignition advance .before top center, retarding the ignition to reduce the engine power during the deceleration, and maintaining the flow of fuel throughout the deceleration.

7. An induction system for a multicylinder gasoline engine, said system having first and second intake manifolds in reciprocally bypassing arrangement, the first manifold has an effective cross-sectional area less than about 5%; square inch for every 100 cubic inches of engine displacement, a carburetion assembly is connected to supply to said first manifold under non-choking conditions a fuel-air mixture varying from an idle mixture of at least about 14 pounds of air per pound of fuel to a power mixture of from about 12 to about 12.8 pounds of air per pound of fuel, the assembly including throttling elements connected to supply a fuel-air power mixture to the second manifold only when these elements call for at least about as much power as obtained when the throttling of the supply to the first manifold is about at its minimum, and heating structure connected to heat the mixture in the first manifold to from 140 to 185 F., and to provide a heating surface for heating the mixture supplied to the second manifold to cause that surface to reach a temperature of about 300 to about 450 F. when the system is operated from a cold start for about 3 minutes under low-speed cruise conditions.

8. The combination of claim 7 in which the carburetion assembly is connected to maintain the supply of fuelair mixture to the first manifold when the fuel-air mixture is supplied to the second manifold.

9. The combination of claim 7 in which the power mixture for the second manifold has no more than about 12.5 pounds of air per pound of fuel.

10. The combination of claim 7 in which the carburetion assembly is connected to supply to the first manifold a mixture that is not temporarily enriched by throttle-opening movements.

11. The combination of claim 7 in which the throttling elements include delay structure connected so that when the throttle control is abruptly closed the throttled mixture delivery rate drops off about 5 to 10% per second when it reaches about 0.4 pound per hour per cubic inch displacement.

12. An induction system for a multicylinder gasoline engine, said system having first and second intake manifolds in reciprocally bypassing arrangement, the first manifold has an effective cross-sectional area less than S; square inch for every 100 cubic inches of engine displacement, a carburetion assembly is connected to supply to said first manifold under non-choking conditions a fuelair mixture varying from an idle mixture of at least about 14 pounds of air per pound of fuel to a power mixture of from about 12 to about 12.8 pounds of air per pound of fuel, said carburetion assembly being further connected to only supply to the second manifold a mixture of from about 11.5 to 12.5 pounds of air per pound of fuel, and to shut off the supply to the second manifold except under maximum engine demand conditions, the second manifold has heating structure connected to provide a heating surface for heating the mixture supplied to the second manifold, and to cause that surface to reach a temperature of about 300 to about 450 F. when the system is operated from a cold start for about 3 minutes under low-speed cruise conditions, the carburetion assembly maintains the ow of fuel through all decelerations and includes delay elements connected so that when the throttle control is abruptly closed the throttled mixture delivery rate drops off about 5 to 10% per second when it reaches about 0.4 pound per hour per cubic inch displacement and the first manifold has an idle stop that provides an air flow to the intake about to 60% greater than the minimum for idling under no road load With 6 ignition advance before top center.

13. The combination of claim 12 and further including ignition mechanism connected to provide no vacuum spark advance when the throttle control is fully closed and to provide idle ignition about 3 to 6 degrees after top center.

14. An induction system for a multicylinder gasoline engine, said system having first and second intake manifolds in reciprocally bypassing arrangement, the first manifold having a cross-sectional area smaller than that of the second manifold, each manifold being connected to a separate source of a fuel-air mixture including a throttle valve that controls the supply of the mixture to that manifold, the cross-sectional areas of the two manifolds being so related that when both throttles are wide open at least about 80% of the fuel-air mixture supplied for combustion will pass through the larger manifold, a control assembly is connected to keep the throttle for the second manifold closed under low power demand conditions and under all other conditions when the throttle for the first manifold is not about fully open, the source of fuel-air mixture being connected to deliver to the larger manifold a fuel-air mixture richer than that delivered to the smaller manifold, and the control assembly includes a pump connected to deliver additional gasoline to the fuel-air mixture for the second manifold Whenever the throttle for the second manifold is opened.

1.5. The combination of claim 14 in which the fuel-air mixture source for the first manifold is connected to supply a mixture that is not temporarily enriched by throttleopening movements.

16. The combination of claim 14 in which the control assembly includes delay elements connected so that when the throttle control is abruptly closed the throttled mixture delivery rate drops off about 5 to 10% per second when it reaches about 0.4 pound per hour per cubic inch displacement.

17. The combination of claim 14 in which the rst manifold has an idle stop that provides an air flow rate to the intake about 20 to 60% greater than the minimum for idling under no road load with 6 ignition advance before top center.

18. The combination of claim 14 in which the second manifold has heating structure connected to provide a heating surface for heating the mixture supplied to the second manifold and to cause that surface to reach a temperature of about 300 to about 450 F. when the system is operated from a cold start for about 3 minutes under low-speed cruise conditions.

19. The combination of claim 14 in which the control assembly includes automatic structure to warn an operator when the throttle of the larger manifold is being opened, and to urge the last-mentioned throttle toward closed position with a force sharply greater than it urges the throttle of the smaller manifold toward closed position.

20. In an induction system for a gasoline engine having a throttle-controlled mixture intake and an exhaust recirculation intake, the improvement according to which the exhaust recirculation intake is throttled and such throttling is connected to cut off the recirculation when the mixture intake throttle is at idle and establish such recirculation at all other throttle positions except near maximum open position.

21. A gasoline engine induction system having two intake manifolds in reciprocally bypassing arrangement, a rst throttle connected to supply fuel-air mixture to one manifold for low power operation, a second throttle connected to supply a fuel-air mixture to the second manifold for high power operation, and additional throttle elements connected to (a) control recirculation of exhaust into the first manifold only, (b) shut off such recirculation when the first throttle is at idle position, and (c) establish such recirculation at about 15% as the first throttle is moved to near maximum open position.

22. The combination of claim 21 in which the first throttle has a throttle valve that is completely closed when at idle position, and the recirculation throttle elements include a similar valve aligned'with and operated simultaneously with the first-mentioned throttle valve.

23. A fuel cut-off control for a gasoline engine, said control including actuator means connected to detect the beginning of an abrupt deceleration from at least about 1200 r.p.m. and to only cut olf the supply of gasoline to the engine in response thereto, said actuator means being further connected to terminate the fuel cut-off when the engine speed is below about 850 r.p.m.

24. The combination of claim 23 in which the actuator means is further connected to terminate the fuel cut-off in response to any power demand on the engine.

25. The combination of claim 24 in which the actuator means includes a conduit for connection to the intake manifold of the engine, and measuring mechanism for measuring the degree of vacuum in the conduit and for controlling the fuel cut-off in response thereto.

26. The combination of claim 7 in which the first manifold has an idle stop that provides an air flow rate to the intake about 20 to 60% greater than the minimum for no road load with 6 ignition advance before top center.

References Cited by the Examiner UNITED STATES PATENTS 1,552,819 9/1925 Brush 123-119 1,623,750 4/ 1927 Pingree 123-127 1,651,250 11/1927 Brownback 123--127 1,680,373 8/1928 Francis 123--122 1,804,754 5/ 1931 Edwards 123-127 1,860,641 5/1932 Woolson 123-119 1,916,952 7/1933 Heitger 123-122 2,033,396 3/1936 Perrine.

2,732,038 1/ 1956 Olson.

2,807,457 9/ 1957 Brueder.

2,886,021 5/1959 Burrell 123-127 2,967,514 1/1961 Riester 123-127 X 2,993,485 7/1961 Cornelius 123-97 3,003,488 10/ 1961 Carlson 123-127 3,037,493 6/1962 Burch 123-52 MARK NEWMAN, Primary Examiner.

KARL I. ALBRECHT, Examiner.

A. L. SMITH, Assistant Examiner.

Claims (2)

1. 6. A METHOD FOR KEEPING A GASOLINE ENGINE FIRING DURING RAPID DECELERATION FROM RELATIVELY HIGH SPEEDS WHILE MAINTAINING GOOD ENGINE BRAKING, WHICH METHOD COMPRISES CHECKING THE RATE OF THROTTLE CLOSURE SO THAT THE REDUCTION OF THE RATE OF MIXTURE FLOW TO THE INTAKE SYSTEM IS ABOUT 5 TO 10% PER SECOND WHEN THE AIR FLOW RATE REACHES ABOUT 0.4 POUND PER HOUR PER CUBIC INCH DISPLACEMENT, LIMITING THE SHUT-DOWN OF INDUCTION MIXTURE FLOW TO AN AIR INTAKE ABOUT 20 TO60% HIGHER THAN THE MINIMUM FOR IDLING UNDER NO ROAD LOAD WITH 6* IGNITION ADAVANCE BEFORE TOP CENTER, RETARDING THE IGNITION TO REDUCE THE ENGINE POWER DURING THE DECELERATION, AND MAINTAINING THE FLOW OF FUEL THROUGHOUT THE DECELERATION.
2. 20. IN AN INDUCTION SYSTEM FOR A GASOLINE ENGINE HAVING A THROTTLE-CONTROLLED MIXTURE INTAKE AND AN EXHAUST RECIRCULATION INTAKE, THE IMPROVEMENT ACCORDING TO WHICH THE EXHAUST RECIRCULATION INTAKE IS THROTTLED AND SUCH THROTTLING IS CONNECTED TO CUT OFF THE RECIRCULATION WHEN THE MIXTURE INTAKE THROTTLE IS AT IDLE AND ESTABLISH SUCH RECIRCULATION AT ALL OTHER THROTTLE POSITIONS EXCEPT NEAR MAXIMUM OPEN POSITION.

Images