Variable area intake manifold for internal combustion
United States Patent [1 1 Loynd 1 VARIABLE AREA INTAKE MANIFOLD FOR INTERNAL COMBUSTION [76] Inventor: Richard S. Loynd, 234 Danbury Rd., Wilton. Conn. 06897 22 Filed: Aug. 8, 1973 211 Appl. No; 386,607  
 [52] US. Cl. .1 123/141; 123/52 M. 123/188 M; 43/180 C; 48/180 M; 48/180 R [51] Int. Cl. F02m 29/00 [58] Field of Search. 123/52 M, 1 11, 119 R, 119 B, 123/188 M; 48/180 R, 180 C, 180 M 3.171.395 3/1965 Bartholomew 123/57 M FOREIGN PATENTS OR APPLICATIONS Germany 123/188 M 1 1 Apr.8,1975  
 Primary Examiner-Wendell E. Burns [57] ABSTRACT A flexible intake manifold for internal combustion engines comprising a flexible tubing made of rubber or plastic being gasoline resistant. The flexible tubing can be used in place of the normal solid wall intake manifold, the flexible tubing having its wall thickness thinned at an intermediate portion thereof whereby the tubing will collapse at the thinned section from its normally circular cross section to a figure eight configuration in response to the manifold vacuum occurring during engine operation. The flexible thinned section of the intake manifold allows its size to be automatically adjusted in a continuous manner responsive to the vacuum produced by the engine.  
 I4 Claims, 8 Drawing Figures PATENTEBAPR&#39; mars snzuzu z nmm nwm  
 VARIABLE AREA INTAKE MANIFOLD FOR INTERNAL COMBUSTION BACKGROUND OF THE INVENTION The present invention relates to an automatic fuel control system for an internal combustion engine, and more particularly, to a flexible or collapsible intake manifold connected between a carburetor or carburetors and the engine.  
  The cross-sectional area of the manifold varies in a continuous manner inversely with the manifold vacuum of the engine, increasing the velocity of the fuel-air mixture sucked into the cylinders in response to the working conditions of the engine, and therefore, helping to break up the fuel droplets for improved fuel atomization.  
  Generally, as is well known in the art, intake manifolds for passenger cars and commercial vehicles are usually made of cast iron or aluminum, while intake manifolds for racing cars are made either of cast aluminum or built up of aluminum tubing. Thus, the crosssectional areas of these intake manifolds are constant and invariable under all engine operating conditions.  
  One of the major problems of modern times is the purification of the atmosphere in which we live. Since the automobile is the worst pollutant of them all, ecology is more than just a fashionable topic. It must be an active part of everyones life or we suffer the consequences. Although many strides are continually made to improve the exhaust emissions and internal combustion engines, great amounts of air pollutants, such as carbon monoxide, carbon dioxide, oxides of nitrogen, hydrocarbons and sulfur dioxide are continually spewed into the atmosphere by millions of cars throughout the United States and in fact, throughout the world. Another crisis becoming ever more apparent is the lack of sufficient fuel to meet the ever growing demand.  
  The fixed cross-sectional area of the manifold discussed above contributes to the aggravation of the above problems due to the inefficient engine operation obtained therewith. Generally, the cross-sectional area of the manifold is designed for maximum efficiency at high engine speeds, but at low speeds, the velocity of the mixture leads to gross inefficiency contributing to poor engine performance.  
  Besides the above broad societal problems, automobiles with fixed manifold cross-sections exhibit several operating difficulties. In cold weather, automotive engines often are difficult to start due to, among other factors, poor vaporization of the air-fuel mixture at low temperatures. The throttle response at low and medium speeds, in many automobiles, is sloppy&#34; due to the low mixture reaching the cylinders. Additionally, because ofthe poor fuel-air atomization at low speeds, excess fuel is utilized to compensate for this situation. Further, high overlap cam shafts are not used generally but are primarily limited to racing type vehicles because oftheir poor low speed characteristics. Even further, poor fuel vaporization and distribution results in poor burning characteristics causing attendant degradation of motor vehicle operation.  
 SUMMARY OF THE INVENTION An object ofthis invention is to overcome the abovementioned disadvantages attendant prior art intake manifolds.  
  Another object of this invention is to provide an improved intemal combustion engine which provides improved starting characteristics in both hot and cold weather.  
  Still another object of this invention is to provide an improved internal combustion engine which allows for reductions in the mixture richness thus improving mileage, conserving energy and reducing exhaust emissions.  
  Another object of this invention is to provide an improved internal combustion engine in which the throttle control is more accurate, thus reducing the use of the carburetor accelerator pump.  
  Yet a further object of this invention is to provide such an automotive engine which improves fuel vaporization and consequently fuel distribution to the engine cylinders during operation.  
  Another object of this invention is to provide such an automotive engine which may be used with high overlap cam shafts without their attendant poor low speed characteristics.  
  Still another object of this invention is to provide such an automotive engine in which the exhaust emission and fuel consumption are considerably reduced.  
  Yet another object of this invention is to provide such an automotive engine improvement which is capable of being adapted to conventional automotive engines, or in the alternative, susceptible to being easily manufactured as original equipment.  
  Other objects, advantages and features of this invention will become more apparent from the following description.  
  In accordance with the principles of this invention, the above objects are accomplished by providing a flexible intake manifold for internal combustion engines which includes a flexible tubing made of rubber or plastic having a thinned wall thickness area, the thinned wall thickness area being vacuum responsive and having its cross-sectional area automatically responsive to the suction or vacuum levels within the cylinders of the automotive engine. In this manner, the mixture velocity is increased at low and medium engine speeds. which contributes to obtaining the above-mentioned objects of this invention. The cross-section of the collapsible flexible tubing is normally circular, and under maximum suction can collapse to a figure eight configuration or any other configuration which will contribute to an improvement in the velocity characteristics of the fuel-air mixture. The flexible tubing may be utilized as the sole intake manifold or may be combined with conventional automotive engines with the fixed crosssection manifold being a secondary, while the present invention would serve as the primary manifold. The reduction in cross-sectional area which increases the velocity of fuel-air mixture helps to break up the fuel droplets to increase atomization.  
  It has been found that by using the present invention, exhaust emissions are reduced, fuel consumption is reduced, horse power output is increased, and the other above-mentioned objects are efficently attained. additionally.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a partial schematic cross-sectional view of an internal combustion engine wherein only a single cylinder, a carburetor and the intake manifold embodying the principles of the present invention have been illustrated.  
  FIG. 2 represents a view similar to FIG. 1, but showing the intake manifold in a collapsed position wherein the cross-sectional area of an intermediate portion thereof is reduced in accordance with the engine intake vacuum.  
  FIG. 3 is a cross-sectional view taken along lines 33 of FIG. 1.  
  FIG. 4 illustrates a cross-sectional view taken along lines 44 of FIG. 2.  
  FIG. 5 is a view similar to FIG. I, but showing another embodiment of the intake manifold of the present invention.  
  FIG. 6 represents a similar arrangement of FIG. 5, wherein the modified intake manifold is illustrated in a collapsed position.  
  FIG. 7 shows a longitudinal cross-sectional view of the intake manifold of the present invention enclosed within an elongated rigid tube as embodied in a supercharged engine; and  
  FIG. 8 is a cross sectional view taken along lines 88 of FIG. 7.  
 DETAILED DESCRIPTION OF DRAWINGS In FIG. 1, there is shown a schematic illustration of an internal combustion engine or fuel consumption means 10 having a plurality of cylinders, but in FIG. 1 only a single cylinder I2 has been represented for clar ity. Each cylinder includes an intake port 14 and an exhaust port, not shown, the intake port 14 being adapted to deliver a fuel air mixture to the combustion chamber I6. The introduction of the fuel mixture into each cylinder is controlled by inlet valve 18.  
  A schematic simplified carburetor or fuel supply source is operatively connected to cylinder 12 which includes a throttle valve 22 for varying the amount of fuel-air mixture that enters the cylinders, a carburetor float bowl 24 wherein the fuel level is maintained at a constant level during engine operation, and air horn 26 directly connected to the atmosphere.  
  The carburetor bowl 24 is connected to a conventional fuel tank and fuel pump (not shown) by a fuel supply line 28. The carburetor 20 is connected to the cylinder 12 through a flexible intake manifold indi cated in general by the reference numeral 30.  
  The intake manifold in its simplified and economical embodiment comprises duct means or a flexible tubing 32 made of a resilient material such as rubber or plas&#39; tic, used in place of the solid wall intake manifold. The tubing 32 is a normal gasoline resistant vacuum tubing having a thinned wall at an intermediate portion 34 with thickened walls 36 at its respective opposite ends. Preferably the thinned portion should be located close to the intake port 14. Due to this particular feature, the tubing 32 will collapse at the thinned portion 34 from its normal circular cross-section 340 as shown in FIG. 3, to a figure eight or dumbbell configuration 34b as shown in FIG. 4, in response to the high manifold vacuum which occurs at engine idle and light load. Other configurations may be achieved under such high vacuum conditions as desired. Further, stiffeners, such as 62 in FIGS. 7 and 8 may be integrated in the thinned section to provide additional structural support as the tubing collapses. These stiffeners may take the form of ribbing integrated within the wall or may be formed of a rigid structural element inserted within the intermedi ate portion about which the thinned wall section collapses.  
  The flexible intake manifold 30 may be connected to the engine either directly or it may be connected to the engine through an auxiliary pipe section or the like, as will be further and more fully explained,  
  In the form of the invention illustrated, the intake manifold 30 is generally horizontally disposed. However, the desirability for changing the relative position of the manifold to the engine, might vary depending on the particular type of engine upon which the intake manifold is to be installed.  
  Mounting flanges 38 are provided to connect the flexible intake manifold 30 to the carburetor 20 and to the engine 10. This is accomplished preferably by affixing the mounting plates 38 to the carburetor 20 and to the engine 10, in any convenient way, for example, by welding or by set bolts 42 as shown in FIG. I. Mounting flanges 38 includes a portion 40 of somewhat smaller diameter than the inside diameter of the tubing 32. Each end of the tubing 32 is mounted onto the portions 40 and held firmly secured in place by clamping means 44 allowing the manifold to be removed easily from the engine.  
  The embodiment illustrated in FIGS. 1 and 2 would be suitable for use as original equipment in automotive engines. The entire fuel-air mixture would be supplied to the cylinders along flexible tubing 32. During idle or light load, a high vacuum or suction is created within the tubing 32 causing it to collapse as shown by numeral 34 in FIG. 2. The amount of decrease in crosssectional area occasioned by the vacuum level will cause a corresponding increase in the velocity of the fuel-air mixture, thereby causing improved operating characteristics. For instance, the higher velocity at engine idel causes improved atomization of the fuel droplets providing more even burning, thereby requiring less fuel and resulting in improved fuel consumption, producing less pollution. The throttle response at low speeds is improved due to the higher velocities in the manifold. Additionally, it has been found by using the present invention, the spark lead requirements at idle and cruise can be reduced resulting in a decrease in the exhaust emissions due to the faster burning created by the improved atomization and resulting improved fuel distribution.  
  As a further benefit of the increased mixture velocity related to the engine vacuum levels, there occurs more complete burning of the fuel, thus decreasing fuel consumption and pollution. In conventional manifolds, at low engine speeds, the velocity of the mixture can fail to carry all of the mixture to the cylinder, and the condition known as manifold wetting occurs. By increasing the velocity and having improved atomization, the mixture more completely reaches the cylinders thus more efficiently utilizing the fuel. Additionally, such an increase in velocity enhances the turbulence of the mixture also improving the burning of the fuel which decreases the fuel consumption and improves the engine operation.  
  FIGS. I-4 illustrate an emobdiment of this invention suitable for use as original equipment, while FIGS. 5-6 illustrate an alternate embodiment which can be used with present manifold systems. Thus, this latter em bodiment may find more ready acceptance by automobile owners seeking to improve the automotive performance without having to purchase a new car.  
  FIGS. 5 and 6 show schematic cross-sectional views similar to the embodiment of FIGS. 1 and 2, wherein a dual intake manifold 50 having at least one flexible or collapsible tubing 32&#39; is connected to primary and secondary carburetors 52-54, respectively, and to the engine 10.  
  The dual intake manifold 50 comprises a primary pipe or tubing 56 and a secondary pipe or tubing 58. The primary tubing 56 is a short extension pipe projecting from the secondary tubing 58 substantially at an acute angle to the longitudinal axis 58:: thereof.  
  The flexible tubing 32 is indirectly connected at one end to the engine 10 by the pipe or tubing 56, and is connected to the primary carburetor 52 at the other end through a curved section 52a of the carburetor 52.  
  The flexible tubing 32&#39; is firmly held onto the curved portion 52a at one end, and onto the pipe or tubing 56 at the other end by clamping means 44 which tightens around the larger wall thickness 36&#39; of the flexible tubing 32&#39;, thereby preventing any undesirable vacuum leakage.  
  The secondary pipe or tubing 58 includes a pair of outwardly extending flange 58b connected to the engine l and to the secondary carburetor 54 through set bolts 42 in such a way that the pipe 58 registers with the intake port 14.  
  Referring now to the embodiment illustrated in FIGS. and 6, it can be seen that the flexible tubing 32 may be used in conjunction either with the secondary carburetor 54 or with the separate small carburetor 52 in accordance with predetermined conditions of the engine. Thus, for instance, the carburetor 54 may be a four barrel carburetor and the carburetor 52 may be a separate low flow carburetor, and the intake manifold 50 will connect both carburetors to the intake port 14 at a point just upstream of the tubing 58.  
  When the engine is idling or decelerating, the suction on the carburetors 52-54 is low because the throttle valves 52b54b are partially closed, and there will be very little air passing through the air horns 52e-54e. Consequently, there will be very little vacuum at that point to draw fuel from the nozzles 520-54c and therefore, fuel will not be sprayed very finely into the cylinder 12. On the other hand, on the manifold sides 52c-58c&#39;, the vacuum will be at the maximum value as long as the throttle valves S2b-54b remain in the closed position.  
  As it is well known, fuel discharge ports 52d-54d are located below the closed position of the throttle valves 52b-54b, and they will supply fuel coming from the float bowls 52f-54f. Atmospheric pressure in the float bowls will force fuel from the idle discharge ports as long as there is some degree of vacuum at the discharge ports. However. due to the fact that high manifold vacuum is generated under this condition, tubing 32&#39; will collaspe as it is shown in FIG. 6, reducing the crosssectional area in response to the engine intake vacuum.  
  The flexible tubing 32 has been thinned at 34 to give the following cross-sectional characteristics, as illustra tive,  
 Full open between inches of Mercury and zero vacuum; begins to draw closed at 10 inches of Mercury and collapses to its smallest cross-section at 18 inches of Mercury.  
 This is approximately normal manifold vacuum at engine idle. When the engine throttle is opened, the flexible thinned section 34 of the manifold 30 adjusts its size to the load of the engine, that load being a direct function of manifold vacuum. If more power is required, the  
 throttle is opened to its maximum and the manifold vacuum drops to almost zero and the flexible tubing 30 opens to its maximum size and allows the engine to produce maximum power.  
  It has been found that with the flexible intake manifold designed in accordance with the principle of the invention, there is practically no need for heat to improve vaporization.  
  The fuel-air mixture speeds are maintained at high values at idle, part throttle and cruise conditions by changing the cross-section of the intake manifold as a function of the load on the engine. This will improve low and medium speed operation where an engine is operated most of the time.  
  The embodiment shown in H68. 1 and 2 may be used with supercharged engines. However, the addition of a guiding tube 60 is preferred to prevent it from expanding excessively due to the positive pressures generated by the supercharger at high R.P.M.  
  The embodiment illustrated in FIGS. 5 and 6 may conveniently be used with present day automotive engines and may be easily adapted to said engines. The flexible tubing 32&#39; may be connected as an additonal intake manifold while the conventional manifold 58 will be used only where extra power is needed. In this instance then, the auxiliary or flexible tubing 32&#39; will replace the conventional manifold as to its function and the throttle 54b may be used and actuated only when the additional power is required. Thus, one need merely modify existing automotive engines by adding the flexible tubing and rearranging some of the connections between the present manifold and the new manifold so as to achieve the improved engine performance without requiring significant modification.  
  With the embodiment of FIGS. 5-6, the flexible tubing can be incorporated in both the pirmary and secondary manifold systems, if desired, with the attendant benefit occurring thereby.  
  The above embodiments have been described with a conventional carburetor. It is to be understood that the present invention may be used with the fuel injection system which is interchangeable with a carburetor in terms of being a fuel supply source. Additionally, the improved characteristics of the present invention may readily be adpated to a Wankel engine.  
  While this invention has been shown and described in certain particular arrangements for illustration and explanation, it will be understood that the structures and illustrations included in this application may be applied to other and widely used types of engines without departing from the spirit and scope of this invention I claim:  
  1. An automatic fuel control system comprising a fuel supply source, a fuel consumption means operating under a vacuum suction to draw a fuel-air mixture therein, and flexible duct means having a collapsible wall being responsive to the amount of said vacuum. one end of said duct means connected to said fuel supply source and the other end connected to said fuel consumption means, the cross-sectional area of said duct means varying inversely continuously with the amount of suction at said fuel consumption means to control the velocity of the fuel-air mixture entering said fuel consumption means,  
 said flexible duct means comprising a collapsible tubing connected at its ends between said fuel supply source and said fuel consumption means, said tubing having thinned walls at an intermediate portion thereof and thickened walls at its ends, said intermediate thinned portion being responsive to the amount of suction of said fuel consumption means whereby the fuel-air mixture velocity varies re sponsive to engine loads. 2. An automotive fuel control system as set forth in claim 1 wherein the cross-section of said intermediate por tion is circular under minimum suction and collapses to a dumbbell configuration at maximum suction of said fuel consumption means. 3. An automotive fuel control system as set forth in claim 1 wherein said fuel supply source comprises a carburetor, and said fuel consumption means comprises an internal combustion engine having a plurality of cylinders including intake and exhaust ports, said carburetor being connected to said internal combustion engine through said flexible duct means. 4. An automotive fuel control system as set forth in claim 3 wherein said duct means comprises a collapsible intake manifold having an intermediate wall thickness portion thinned at the manifold intersection with the intake port of said cylinders. 5. An automotive fuel control system as set forth in claim 4 wherein said cylinders are individually connected to at least one carburetor through said intake manifold. 6. An automotive fuel control system as set forth in claim 3 wherein said duct means comprises a dual manifold having at least one collapsible tubing having a cross-sectional area being responsive to the suction of said engine. primary and secondary carburetors connected to said engine through said dual manifold to supply a fuel-air mixture at a velocity which is a function of the amount of vacuum of said engine. 7. An automotive fuel control system as set forth in claim 6 wherein said dual manifold comprises primary and LII LII  
  8 secondary tubings. said primary tubing projecting from said secondary tubing at an acute angle to the direction of fuel-air mixture supply, said collapsible tubing having one end connected to said primary tubing and the other end connected to said primary carburetor to control the velocity of the fuel-air mixture entering said cylinders, said secondary tubing being connected to said cylinders to supply an auxiliary fuel-air mixture therein in response to the operating condition of said engine. 8. An automotive fuel control system as set forth in claim 7 wherein said dual manifold is connected to each cylinder of said engine and to said primary and secondary carburetors to supply said fuel-air mixture to the cylinders in accordance to a predetermined condition of said engine. 9. An automotive fuel control system as set forth in claim 1 wherein the collapsible tubing is made of a resilient material. 10. An automotive fuel control system as set forth in claim 9 wherein said resilient material is fuel resistant. 11. An automotive fuel control system as set forth in claim 9 wherein said resilient material is rubber. 12. An automotive fuel control system as set forth in claim 9 wherein said resilient material is plastic. 13. An automotive fuel control system as set forth in claim I further comprising an elongated rigid tube. said collapsible tubing being enclosed within said elongated tube to prevent excessive expansion of said collapsible tubing due to positive pressures generated at said fuel consumption means. 14. An automotive fuel control system as set forth in claim 1 wherein said intermediate portion is provided with stiffening means to control the corsssectional configuration ofthe flexible duct means in its collasped state.