BACKGROUND OF THE INVENTION

Field of the Invention

This invention relates to new automotive gasolines having intermediate carbon ranges, and their improved use in internal combustion engines. In particular the invention relates to new gasoline for use in improved gasified carburetion systems.

Badcgro ^y -T-d "reformation Present day automotive gasoline consists of a mixture of hydrocarbons which range from C to about C ₁₂ . The lower molecular weight fraction, such as butane isomers, is more volatile and it has always been the practice to include substantial portions of these volatiles in the fuel to insure proper engine performance. This practice, however, is at best a compromise since the presence of the volatiles, on the one hand, causes an undue risk of explosion during storage and handling; and the inherent evaporative and emission losses contribute to pollution; but, on the other hand, the volatiles have always been considered necessary for good cold engine starting. Thus, a certain amount of the volatiles have been incorporated in gasoline. The exact amount of the volatiles may vary according to the climate where it is sold. In fact, industry has set voluntary limits so that each area will have a motor fuel having sufficient volatility for the prevailing climate. High levels of volatile components assure satisfactory starting and warm-up at the lowest

temperature expected, and low levels of volatile component protect against vapor-lock in high temperature climates.

Generally current gasolines exhibit high levels o volatiles measured in terms of Reid Vapor Pressure. Rei Vapor Pressure is the accepted measurement of gasolin volatility and it represents the vapor pressure at 100° (37.78°c). current fuels require a relatively high amoun of volatile components which raises the Reid Vapor Pressur to undesirable levels. It is highly desirable to formulat a fuel which satisfies the volatility requirements withou raising the Reid Vapor Pressure to the undesirable leve found in the prior art fuels.

The use of these volatiles in prior art fuels i associated with several problems. One such problem is tha because present day engines depend on the volatiles, th spontaneous loss of them in storage results in a the fue which is of inferior quality after a period of storage Thus, because of varying storage times, the consumer ca never be certain if the gas he is purchasing contains th required amount of volatiles at the time of purchase Naturally, therefore, a fuel whose efficiency an dependability is less dependent on the presence o volatiles is more desirable.

Another problem arising out of the use of thes volatiles is the evaporative loss of gasoline which ca occur in the gas tank. Industry has been hard pressed t solve this problem for quite some time. While this proble has been recognized for some time, industry has always bee reluctant to solve the problem by reducing the volatilit of the gasoline because in doing so they would lose th benefits of the compromise (i.e.. engine performance) . I fact, this point has been expressed in the publicatio titled Effects of Automotive Emission Requirements o Gasoline Requirements: Symposium, American Society fo

Testing and Materials; 1971. Here it is stated on page 111 that "Severe volatility reduction could produce other problems. A more effective method than volatility reduction can be seen to be the elimination of evaporative losses by some mechanical device". This invention, however, seeks to reduce volatility or Reid Vapor Pressure and still maintain a fuel which can perform well.

Present day gasoline also contains, in addition to the volatile light-weight and the intermediate-weight components, a heavy-weight component which, like the volatile component, is also associated with several disadvantages. For example, the gasoline of today, when used as a fuel in present day short stroke engines, results in incomplete combustion because there is insufficient time or temperature to burn the heavy hydrocarbon components. This results in a certain amount of gasoline being wasted and this contributes to pollution. Conventional C ₄ -C ₁₂ has too much energy in it for conventional internal combustion engines in that if combusted with enough air (stoichiometric or slightly above) it will burn too hot for the engine or it will produce high levels of nitrous oxides. Yet, in spite of these shortcomings, the heavy components are left in present day fuel because their presence is considered necessary to provide a fuel having suitable properties for automotive use.

The presence of these heavy components in conventional C ₄ -C _.2 gasoline requires considerable front end priming with light components (C ₄ and/or C ₅ ) to achieve adequate front end volatility for starting engines equipped with standard carburetion systems. In addition, conventional C ₄ -C ₁₂ gasoline which contains these heavy components (C _n and C ₁₂ ) cannot be easily gasified and maintained in the gaseous state without recondensing. Consequently, conventional "" ₁₂ gasoline has limited utility in a more efficient carburetion system of the type which requires gasification

in the absence of air before mixing the gasified fuel with air for combustion. Therefore, in view of the shortcomings associated with the heavy weight hydrocarbons, especially C-- and C ₁₂ , it would be highly desirable to formulate the gasoline without these heavy components being present while also avoiding the problems associated with the absence of these components.

The use of conventional C ₄ -C ₁₂ fuels in standard carbureted internal combustion engines requires that the volatility of the fuel be adjusted to achieve a Reid Vapor Pressure of at least 9 in the summer and 12 in the winter. If the Reid Vapor Pressure of conventional C ₄ -C ₁₂ gasoline falls below the above limits, starting and running the engine is severely impaired. The fuels of the present invention will easily start and operate identical engines yet these fuels have a reduced Reid Vapor Pressure in comparison to the above-mention conventional C ₄ -C ₁₂ gasoline. Thus the summer fuels of the present invention may have a Reid Vapor Pressure less than 9 and the winter fuels may have a Reid Vapor Pressure of less than 12. In particular, it is been discovered that the fuel of the present invention having a Reid Vapor Pressure as low as 6 in the summer and 9 in the winter will easily start and operate identical engines which require conventional fuels having a Reid Vapor Pressure of 9 in the summer and 12 in the winter. The Reid Vapor Pressures can be reduced even further by using the fuels of the present invention in combination with the improved carburetion system of -the present invention.

The ideal combustion mixture for internal combustion engines consists of gasoline in the vapor or gaseous state thoroughly mixed with adequate air to support combustion. In this condition, fuel-rich pockets, which are responsible for detonation or "knock," are eliminated and carbon deposits responsible for preignition are minimized due to

more complete combustion. Because detonation or preignition can damage or ruin an engine, current gasolines have octane boosters such as aromatics contained therein to reduce "knock" since current engines have fuel and air intake systems which produce droplets of fuel that contribute to fuel rich pockets in the combustion chambers of the engines. Slowing the burn with octane boosters lowers the combustion efficiency of the engine and increases the exhaust pollution. Therefore, it would be highly desirable to provide a fuel which avoids octane boosters, is rated at a lower octane value but which has highly desirable burning characteristics so that the fuel does not produce engine knock.

Automotive and aviation gasolines have always had an ASTM average octane number ( ^R+H / ₂ ) of 80 or higher; wherein

R represents the research octane number and M represents the motor octane number, current engines generally require an average octane number in excess of 85.

SUMMARY OF THE INVENTION

A primary object of this invention is to provide an improved gasoline which facilitates the achievement of ideal combustion mixtures for internal combustion engines.

Another object of this invention is to provide a lower octane fuel and method of use so as to further improve the combustion efficiency of the fuel in an internal combustion engine.

A further object of this invention is to provide a method whereby greater combustion efficiencies can be achieved in engines.

It is an object of this invention to provide gasolines for automotive engines which minimize the requirement for

volatile components in the fuel without sacrificin adequate engine performance and which lowers the Reid Vapo Pressure while maintaining good front end volatility.

It is also an object of this invention to provide gasoline having a low Reid Vapor Pressure which combust more efficiently than conventional gasoline of the typ having a hydrocarbon range of C ₄ -C ₁₂ .

It is another object of this invention to provide gasoline which has greater tolerance for alcohol enrichmen because of low Reid Vapor Pressure.

It is yet another object of this invention to provid a gasoline which minimizes the priming needed to achiev adequate front end volatility for starting engines equippe with standard carburetion systems.

It is a further object of this invention to provide a improved gasoline which has enhanced gasificatio characteristics in improved carburetion systems.

It is another object of this invention to provide a improved process for more completely combusting the fuel o this invention in an engine thus negating the need for fue injection systems or catalytic converters.

These and other objects of the invention will becom apparent to those skilled in the art from the followin disclosure of the invention.

The objects of the present invention are achieved b the discovery that front-end priming of gasoline is no necessary in gasifier type carburetors and that the heavie components in gasoline are not stable as gases in air usin gasifier type carburetors. Therefore it was possible t develop new intermediate hydrocarbon range gasolines tha

have unique benefits not obtained in c ₄ -c ₁₂ gasoline. in addition the new gasification methods have distinct advantages over the prior art.

One aspect of the invention relates to a gasoline having an intermediate hydrocarbon range relative to conventional C ₄ -C ₁₂ gasoline which contains C ₄ , C ₅ , C ₆ , C _7/ c ₈ , c ₁₀ , c-n and c ₁₂ hydrocarbons. The intermediate range gasoline is made by removing the lighter volatile component as well as the heavier component from a conventional gasoline starting material. The resulting fuel is C ₆ -C ₁₀ ; i.e. the hydrocarbons are limited to those in the range C ₆ -C ₁₀ . Also, in accordance with this aspect of the invention, it may be desirable to further remove the C ₁₀ component to form a C ₆ -C ₉ gasoline for improved winter performance in gasifier type carburetors.

Suitable starting material to produce the gasoline of this invention is conventional gasoline having a range of C ₄ -C ₁₂ . Both the heavy and light components are removed by any of the known methods currently available such as heat fractionization or the use of heat and vacuum in the absence of air. Once removed, the heavy component may be "cracked" at the refinery to make more gasoline and the volatile component, most of which is being wasted today, may be fully recovered at the refinery.

Although gasoline having a range of C ₄ -C ₁₂ is mentioned as a useful starting material, it is not critical that the starting material be precisely in this range. Rather, it is the essence of this invention to produce a gasoline fraction of intermediate carbon range relative to the given range C ₄ -C ₁₂ that may be produced directly from refinery hydrocarbon streams.

It will be apparent, of course, that the C ₆ -C ₁₀ and C ₆ -C ₉ fuels of the invention cannot be used efficiently in

conventional internal combustion engines withou modification of the carburetion system. It has been found, however, that the gasoline of this invention can be quickl volatilized in a heated chamber by heating to a temperatur above final boiling point of the fuel at one atmospher pressure in the absence of air, and such apparatus can b readily installed in an automobile. The resulting vapo

(produced as needed) will mix readily with air to form homogenous mixture without formation of condensed droplet which can wet the wall in an internal combustion engine; will not be subject to liquid phase oxidation prior t ignition; and will ignite well in the gaseous form.

Since not all the C ₆ -C ₁₀ and C ₆ -C ₉ gasoline can be use efficiently in a conventional internal combustion engin without modification of the carburetion system, the presen invention also provides an improved fuel for use in car having standard carburetion systems. In connection wit this, it has been discovered that the above described C ₆ -C ₁ and C ₆ -C ₉ gasoline can be used in an internal combustio engine having a standard carburetion system by priming th gasoline with a minimum amount of C ₄ ,C ₅ or a mixture of C and C ₅ to produce a gasoline having adequate front en volatility for starting cars equipped with standar carburetion systems. Since the gasoline may be primed wit c ₄ and/or C ₅ , then the permissible range of such a fue will be C ₄ -C ₉ (winter) and C ₄ -C ₁₀ (summer) . In particular, it has been discovered that the amount of C ₄ or C ₅ primin necessary for achieving adequate front end volatility ^~ for starting engines equipped with a standard carburetio system is less than the amount required with conventiona C ₄ -C- ₁₂ gasoline. Thus, this aspect of the invention provide an improved fuel for standard carbureted engines and thi fuel will advantageously contain less C ₄ or C ₅ tha conventional C ₄ -C ₁₂ gasoline while maintaining adequat front end volatility and reduced Reid Vapor Pressures. I other words, the C ₆ -C ₁₀ and C ₆ -C gasoline requires les

priming to achieve adequate front end volatility for starting engines equipped with standard carburetion systems than does normal C ₄ -C ₁₂ automotive gasoline. This represents a unique and unexpected method of achieving lower Reid Vapor Pressure in automotive gasoline while maintaining adequate-front end volatility since one would assume that lighter gasoline (C ₄ -C ₉ and C-C ₁₀ ) would have higher Reid Vapor Pressure than heavier C ₄ -C ₁₂ gasoline.

The amount of C ₄ , C ₅ or mixture of C ₄ and C ₅ used to prime the C ₆ -C ₁₀ or C ₆ -C ₉ gasoline is a minimum amount necessary to achieve adequate front end volatility for starting a car equipped with a standard carburetor.

The C ₄ -C ₀ and C ₄ -C ₉ gasoline can also be made by removing the heavy and light components from gasoline as described above for making C ₆ -C ₁₀ and C ₆ -C ₉ with the exception that an adequate amount of C ₄ and/or C ₅ is retained in the product to achieve adequate front end volatility for starting a car equipped with a standard carburetor.

It has also been discovered that adequate front end volatility for engines equipped with standard carburetion can be achieved by priming with additional C ₅ so that adequate front end volatility can be achieved without any C ₄ priming.

It has also been discovered that prior art gasoline having a carbon range of C ₄ to C ₁₂ can be improved by removing the higher molecular weight constituents so as to produce a gasoline fuel having a narrower carbon range of C ₄ to Cn and a boiling point range of ll ^β P to 38 °F (-11.7 to 195.6°C). Such a narrower range fuel facilitates both the ability of the gasoline to be vaporized or gasified as well as the ability of the vapor or gas to remain as a vapor or gas when mixed with ambient air without forming

droplets which can wet the surface in an interna combustion engine. This narrower fuel allows idea combustion mixtures to be used in internal combustio engines and, in turn, allows lower octane gasoline to b used which further improves combustion efficiency an lowers the production of pollutants produced durin combustion.

Prior art aviation gasoline having a carbon range o c ₄ to C would not require the removal of higher molecula weight constituents to be stable as a vapor or gas i ambient air but the use of such prior art fuels woul require the lowering of the octane to increase the speed o burn, thus improving combustion efficiency and lowering th pollutants produced during combustion.

Since the temperature of intake air used in an engin can vary widely because of seasonable variations o altitudes, the amount of heavy molecules removed can vary Preheated intake air systems could utilize more of th energy contained in the dense heavier molecules but thi would result in too much loss in volumetric efficienc caused by the preheating or preexpansion of the intake air

The conversion of the fuels of this invention int vapors or gasses, homogenizing these vapors or gasses wit intake air (ambient or heated) while maintaining gas o vapor stability and combusting this fuel mixture in a engine represents an improved method for achieving highe combustion efficiency while lowering the pollutants o combustion.

Brief Description of the Drawings Figure 1 is a graph which illustrates the fue efficiency of selected fuels in a 1500 c.c. Volkswage engine at various engine speeds. The vertical axis show the efficiency in term of lbs. of fuel/horsepower hour

The horizontal axis measures the engine speed. Figure 1 also illustrates the fuel efficiency of the gasoline of this invention combusted in an identical engine equipped with the improved carburetor of this invention.

DETAILED DESCRIPTION OF THE

INVENTION AMD PREFERRED EMBODIMENTS

In the manufacture of a gasoline in accordance with a preferred embodiment of the present invention, both the lighter volatile component and the heavier, slow-burning component are removed from gasoline in the C ₄ -c ₁₂ range. The removal of the volatile component makes the resultant fuel have a slower rate of burning. By also removing the heavy slow-burning component, the resultant fuel is an intermediate gasoline having a burn rate comparable to or better than the starting stock gasoline (C ₄ -C ₁₂ ) from which it was made.

The most abundant of the volatile components in conventional C ₄ -C ₁₂ gasoline is butane and pentane. With regard to the removal of the volatile components it is primarily the butane and pentane which is removed from the ^C ₄ " ^C ₁₂ gasoline in the practice of this invention. If the gasoline contains hydrocarbons lighter than butane, it is desirable that they too be removed. The heavy, slow-burning component consists primarily of C^ and C ₁₂ , each of which exists in numerous isomeric forms. These are removed and, if the starting stock gasoline contains hydrocarbons greater than C ₁₂ , it is desirable that they also be removed. In both cases the light volatile components and the heavy, slow-burning components are removed according to conventional known methods.

In the practice of a preferred embodiment of this invention, both components are removed, resulting in an intermediate hydrocarbon range. The boundaries of this

range depend upon the extent to which the heavy and ligh components are removed. In this invention, both component are substantially removed but it is recognized that som may be left behind due to imperfections in curren fractionation techniques. It is most desirable that th heavy and light components be substantially removed.

It is also recognized that the heavy and ligh components do not exist as absolutes but rather, as points on a continuum with the most volatile being the lighte hydrocarbons, and a gradual reduction in volatility an burning tendency as the weight is increased. This gives rise to certain "border line" components near both ends of the continuum. It is inevitable that some of these will be removed with the heavier and the lighter components. I general, it is recognized that the border line weights are C ₆ and C ₁₀ . Thus, according to this invention, a substantial quantity of volatile component is removed to effectivel reduce the potential for explosion and minimize the loss of gasoline due to evaporation. Likewise, the heavy componen is also removed in an effective amount to raise the bur rate of the fuel and effect more complete combustion. Bot of these components are removed and this fuel is used wit an improvement in fuel combustion efficiency and engin performance.

This improvement is illustrated in Figure 1. It will be noted that Figure 1 shows a comparison which measure the efficiency of the fuel of the present invention versus the efficiency of conventional C ₄ -C ₁₂ prior art fuels a various engine speeds. The fuel efficiency is measured i terms of Brake Specific Fuel Consumption (lbs. of fuel pe horsepower hour) . Lower Brake Specific Fuel Consumptio values indicate better fuel efficiency.

The C ₆ -C ₁₀ fuel of this invention may be used to run a engine equipped with the improved gasifier carbureto

described herein. However, it is not necessary that volatile components be absent from the fuels used in the improved gasifier combustors since their presence in the fuel does not hinder the gasification process. Thus, some volatile C ₄ and/or C ₅ may be added to the C ₆ -C ₁₀ fuel so that the fuel can be used in a standard carbureted engine as well as an engine equipped with the improved gasifier carburetor. For this reason the comparison presented in Figure l utilized a C ₆ -C ₁₀ fuel containing some C ₅ volatile component so that the resulting C ₅ -C ₁₀ fuel will run an engine equipped with an improved gasifier carburetor as well as a standard carbureted engine. The C ₅ -C ₁₀ has a boiling point range about 49 ^β F-345 ^β F (9.4 to 174°C).

In order to obtain the data shown in Figure 1, identical engines were used to compare conventional C ₄ -C ₁₂ unleaded gasoline (line A) with the C ₅ -C ₁₀ fuel of this invention (line B) . An identical engine was used to test the use of Cs-C ₁₀ fuel in an improved carburetion system of the present invention (line C) . It will be noted by comparing line A with line B that at all engine speeds, more pounds of fuel are required per horsepower hour for the c ₄ -c ₁₂ gasoline than for the c ₅ -c ₁₀ gasoline of the present invention. Therefore, the C ₅ -C ₁₀ is significantly more efficient when combusted in identical engines. It will also be noted from Figure 1 that an even greater efficiency is observed when the C ₅ -C ₁₀ fuel is combusted in an identical engine equipped with the improved carburetion system of the present invention.

In a preferred embodiment of this invention, the C-C ₁₂ gasoline is used as a starting ingredient from which the volatile C ₄ and C ₅ constituents and the heavy C _n and C ₁₂ components are removed. In the preferred embodiment the starting C ₄ -c ₁₂ gasoline contains a mixture of each of the hydrocarbons (i.e. - a mixture containing C ₄ , C ₅ , C ₆ , C ₇ , c ₈ , c ₉ , C ₁₀ , Cn and C ₁₂ ) . Consequently, the intermediate C ₆ -C ₉

and C ₆ -C ₁₀ gasoline of the preferred embodiment will likewis contain the same intermediate hydrocarbons which ar present in the starting gasoline. In other words, C ₆ -C will contain, C ₆ , C ₇ , C ₈ , and c ₉ and the C ₆ -C ₁₀ gasoline wil contain, C ₆ , C ₇ , C ₈ , C ₉ and C ₁₀ hydrocarbons.

The fuels of the present invention have a intermediate hydrocarbon range relative to conventiona gasoline which has a hydrocarbon range of C ₄ -C ₁₂ . Th conventional C ₄ -C ₁₂ gasoline contains paraffinic hydrocarbon including C ₄ , C ₅ , C _6/ C ₇ , C ₈ , C ₉ , C ₁₀ , C^ and C ₁₂ paraffini hydrocarbons. Thus removing the C^ and C ₁₂ paraffini components of the C ₄ -C ₁₂ fuel will result in a fuel whic contains paraffinic hydrocarbons, including paraffinic C and C ₁₀ which were originally present in the C ₄ -C ₁ paraffinic fuel from which the fuel of this invention ma be derived.

Preferably the C ₄ -C ₁₁ fuel should be formulated, wit or without additives, to produce a maximum Reid Vapo Pressure of less then 5 psi. Such a fuel is particularl suitable for gasifier engines or other engines havin enhanced vaporization capability. However, a C ₄ -C ₁₁ fue having a maximum Reid Vapor pressure of less than 5 psi i not suitable for combustion in a standard or conventiona carbureted engine. A full range Cβ~ ^c fuel has RVP whic is less than 5 psi. A C ₄ -C fuel can be easily formulate to meet this criteria by the appropriate selection of C ₄ -C ₁ constituents so as to limit the RVP to less than 5 psi.

In one embodiment of the present invention the ligh and heavy components are removed from conventional C ₄ -C ₁ gasoline to produce a gasoline having a hydrocarbon rang of C ₅ -C ₁₀ . Such a fuel is identical to the C ₆ -C ₁₀ fuel wit the exception of the presence of C ₅ component in the C ₅ -C ₁ fuel. Thus the c ₅ -c ₁₀ fuel will have a boiling point rang Of about 49°F-345 ^β F (9.45 to 174°C) .

Although the starting gasoline preferably contains the entire range of hydrocarbons from C ₄ -C ₁₂ as described above, it is not absolutely essential that all of the intermediate hydrocarbons be present in the starting gasoline. However, it is critical that the C ₆ -C ₉ fuel contains C hydrocarbon and the C ₆ -C ₁₀ gasoline contain C and C ₁₀ hydrocarbon.

The preferred intermediate range C ₆ -C ₁₀ gasoline may be defined as the portion remaining when C ₄ -C ₁₂ gasoline has removed therefrom an effective amount of lower weight volatile components to substantially reduce evaporative loss and explosion potential and effective amount of higher weight components to raise the burn rate of the remaining hydrocarbons. A C ₆ -C ₁₀ gasoline which has these characteristics can be made by removing the volatile and heavy components so that the remaining hydrocarbon mixture will boil within a range of about 121°F-345°F (49.4 to 174°C) at one atmosphere. Such a boiling point range encompasses the boiling point of the lowest boiling C ₆ component and the highest boiling C ₁₀ component. Of course, it is possible that a small amount of C ₄ , C 5, C-n and C ₁₂ may remain after the separation process due to imperfections of gasoline fractionation procedures.

Since the largest hydrocarbon in the preferred C ₆ -C ₁₀ gasoline is C ₁₀ , then the final boiling point of such a mixture will be 345°F (174°C). It has been discovered that hydrocarbons having boiling points above 350"F (177°C) must be substantially eliminated so that the intermediate fuel can be gasified in a heated chamber in the absence of air, and then mixed with ambient air (i.e.. about 70°F or 21°C) without condensing to form droplets of heavy hydrocarbons which could wet the surfaces in an internal combustion engine. However in warm or hot climates C may be included without resulting in the formation of droplets which could wet the surfaces in an internal combustion engine. This property is an essential aspect of the C ₆ -c ₁₀ gasoline

because the C ₆ -C ₁₀ fuel is used in a modified carburetio system in which the fuel is gasified in a heated chambe and then mixed with air for immediate combustion in a automotive internal combustion engine. The absence o condensed droplets allows the gasoline to burn much mor efficiently than conventional C ₄ -C ₁₂ gasoline and consequently, reduces pollution and improves engin performance. By removing C-n and c ₁₂ components from th starting stock gasoline, the final boiling point will b 345°F (174°C) and, thus, the gasoline will have the desire gasification property.

The gasification system used for intermediat hydrocarbon range gasoline requires heating the gasoline t lower temperatures that would be required for th gasification of C ₄ -C ₁₂ gasoline. When lower temperatures ar attained, the volumetric efficiency of the air and ga mixture going into an engine is improved.

The gasoline having hydrocarbons comprised essentiall of C ₆ -C ₁₀ hydrocarbons will have lower Reid Vapor Pressur than conventional C ₄ -C ₁₂ gasoline with functional Reid Vapo Pressures less than two. Nonetheless, the C ₆ -C ₁₀ gasolin will exhibit good ignition properties in the gaseous stat when mixed with air. It will also provide excellent engin starting ability, will have reduced explosive potential an will burn more completely than C ₄ -C ₁₂ gasoline. In addition the C ₆ -C ₁₀ gasoline will burn cooler in the engine with th modified carburetor and consequently the use of such a ^' fue will result in less lubrication requirements for th engine.

Conventional C ₄ -C ₁₂ gasoline has high Reid Vapo Pressure and the Reid Vapor Pressure can be adjuste somewhat to provide summer or winter fuels. For example the Reid Vapor Pressure can be increased by addin volatiles such as C ₄ to enhance the winter performance o

the conventional gasoline. However, the present C ₆ -C ₁₀ invention requires lowering the Reid Vapor Pressure by removing the C ₄ and C ₅ components. Thus it would be expected that ability to formulate winter and summer fuels would be lost if the hydrocarbon range is limited to essentially C ₆ -C ₁₀ hydrocarbons. It is therefore surprising that the c ₆ -c ₁₀ gasoline can be formulated for winter use without additional C ₄ priming. It has been discovered that a winter fuel can be made in the same manner as the C ₆ -C ₁₀ summer gasoline with the exception being that the C ₁₀ component is additionally separated from the starting C ₄ -C ₂ gasoline along with the C ₄ , C ₅ , C and C ₁₂ components to provide a fuel that when gasified will remain substantially a gas when mixed with colder air. Thus, the present invention also provides a winter fuel having hydrocarbons which consists essentially of hydrocarbons in the range C ₆ -C . The C ₆ -C ₉ winter gasoline differs from the C ₆ -C ₁₀ gasoline only in the elimination of the C ₁₀ component which is left in the C ₆ -C ₀ summer gasoline. Consequently, the winter C ₆ -C ₉ gasoline has a final boiling point of 303°F (15l°C) and a boiling range of about 121°F-303*F (49 to 151"C).

The C ₆ -C gasoline must contain the C ₉ hydrocarbon component and preferably should contain the remaining intermediate hydrocarbons which are C ₆ , C ₇ , and C ₈ since these are preferably present in the C ₄ -c ₁₂ gasoline. The C ₆ -C ₉ winter gasoline is burned in an engine in the same manner described above with respect to the C ₆ -C ₁₀ gasoline and enjoys the same benefits described above with respect to the C ₆ -C ₁₀ gasoline.

The C ₆ -C ₁₀ and C ₆ -C ₉ gasoline is gasified by heating in a chamber in the absence of air to a temperature above the final boiling point of the gasoline. The c ₆ -C ₁₀ and c ₆ -c ₉ fuels are preferably heated to a temperature 350°F (177°C). Higher temperatures may be used but are not necessary.

Conventional C ₄ -C ₁₂ would require a temperature of about 75° (24°C) higher to gasify and when mixed with air it wou still have the problem of forming condensation droplet Additionally, the higher temperature would lower t volumetric efficiency of the engine.

It has been emphasized that C-, and C ₁₀ must be prese in the C ₆ -Cιo gasoline and C must be present in the C ₆ - gasoline because heavy molecular components have t highest energy density. Since these are the highes density components capable of being gasified and remaini a gas when mixed with air, it is important that they remai in the gasoline for production of engine power.

It has also been discovered that the C ₆ -C ₁₀ and t C ₆ -C ₉ gasoline can be adapted for use in engines havi standard carburetion (i.e. - carburetors which do no require gasification in a heated chamber in the absence o air) . In particular, it has been discovered that primi the C ₆ -C ₉ and the C ₆ -C ₁₀ gasoline with a small amount of volatile component will result in the production of a improved gasoline which may be used in automobiles equippe with standard carburetion. The priming agent may be C _4/ C ₅ or a mixture of C ₄ and C ₅ . Consequently the primed gasoli will have hydrocarbons which consists essentially o hydrocarbons in the range C ₄ -C ₁₀ (summer) and C ₄ -C (winter) The C ₄ -C ₉ and C ₄ -C ₁₀ gasoline is the same as the analogo C ₆ -C ₉ and C ₆ -C ₁₀ gasoline except for the presence of a smal amount of priming agent in both the C-C and C ₄ -C gasoline.

In both the winter and summer fuel, the amount priming agent is an amount effective to raise the front e volatility so that the fuel can be used in cars equipp with standard carburetion. Thus the c ₄ -c ₉ is particular suitable for winter use and the C ₄ -C ₁₀ is particular suitable for summer use in cars equipped with standa

carburetors. It is particularly significant and surprising that the amount of C ₄ or C ₅ in the C ₄ -C ₉ and C ₄ -C ₁₀ gasoline is less than the amount of C or C ₅ in conventional C ₄ -C ₁₂ gasoline without sacrificing any of the desirable properties of the gasoline. It is also surprising that the C ₄ -C and C ₄ -Cιo gasolines have adequate front end volatility yet are lower in Reid Vapor Pressure than conventional C ₄ -C ₁₂ gasoline. It is believed that this is because removal of C _n and C ₁₂ from C ₄ -C ₁₂ gasoline means that the remaining fuel will have a higher percentage of C ₄ , C _s , and C ₆ hydrocarbons, therefore much of the C ₄ and some of the C ₅ hydrocarbons can be removed from the C ₄ -C ₁₀ and C ₄ -C gasoline to obtain a functionally equivalent front end volatility in comparison to the original C ₄ -C ₁₂ gasoline. This reduces the Reid Vapor Pressure.

The gasoline of this invention may also contain any of the various additives presently in use or known to be useful in gasoline. In fact, because this invention produces a gasoline having a low Reid Vapor Pressure, as compared to normal automotive gasoline, it is possible to add large amounts of alcohol such as ethanol to the gasoline of this invention without raising the Reid Vapor Pressure above the current allowable limits. Alcohol addition to conventional gasoline is known to raise the Reid Vapor Pressure above the allowable limits. Additions of alcohol can be added to the fuels of this invention in an amount of 10-20 per cent by weight without exceeding current Reid Vapor Pressure standards.

It is also possible to add lubricants or anti-knock compounds to the gasoline. For example, a suspension of fine synthetic upper end lubricants or small amounts of anti-knock compounds may be added the gasoline of this invention.

It has also been surprisingly discovered that th fuels of this invention when gasified burn almos completely in the engine producing equivalent torques wit less fuel and at temperatures which are lower than th temperatures achieved when combusting conventional fuels i engines equipped with standard carburetion systems. Thi is true at stoichiometric or slightly higher air-to-fue ratios which would normally result in the development o excessive engine temperature. Therefore, combusting th gasoline of this invention produces less nitrous oxide an allows some increase in compression or superchargin without damage to the engine and without environmenta contaminatio .

The gasoline of this invention is an intermediat hydrocarbon fuel and naturally exists in the liquid stat at standard temperature and pressure. Thus the gasolin can be shipped, stored and dispensed like conventiona gasoline and requires no further processing for use.

It has also been discovered that the fuels of thi invention burn cooler than conventional C ₄ -C ₁₂ fuel. Fo this reason may be advantageous to add an oxygen source t the fuel to obtain more complete combustion. The oxyge source raises the combustion temperature. However, due t the fact that the fuels of the present invention bur cooler than conventional C ₄ -C ₁₂ gasoline, the elevate combustion temperature can be tolerated in automobil engines. Thus, an oxygenate compound may be added to- th fuels of the present invention to raise combustio temperatures or to effect more complete combustion. Man suitable oxygen source may be used. Typical oxygen source include oxygenated hydrocarbons such as l, 2 butylen oxide.

Example 1 C ₅ -C ₁₀ fuel was made by removing the hydrocarbons lighter than C ₅ and the hydrocarbons heavier than C ₁₀ from a conventional C-C-| ₂ gasoline. The C ₄ -Cι ₂ gasoline which served as the starting ingredient contains C ₅ , C ₆ , C ₇ , c ₈ , Cc,, and c ₁₀ hydrocarbons in addition to the heavy and light hydrocarbons which were removed therefrom. The resulting C ₅ -Cιo fuel therefore contains C ₅ , C ₆ C ₇ , C ₈ , Cς,, C ₁₀ hydrocarbons. The C ₅ -C ₁₀ fuel had a Reid Vapor Pressure of 6. The fuel was used to start and run a standard carbureted Volkswagon engine. Measurements of fuel efficiency were taken and the results are shown in Table I, (line B) . During the test it was noted that the standard carbureted engines started and ran easily even though the fuel had a Reid Vapor Pressure of only 6.

Example 2 For the purpose of comparison, the C-C ₁₂ fuel described in example 1 was used to start and run a Volkswagon engine which was identical to the engine used for testing the C ₅ -C ₀ fuel in example 1. The C-C ₁₂ fuel had a Reid Vapor Pressure of 10. The efficiency of the C ₄ -C ₁₂ fuel was measured and the results are shown in Figure 1 (line A) .

Example 3 The C ₅ -C ₁₀ fuel used in example 1 was also tested in an engine identical to the engine used in example l with the exception that the engine used in example 3 was equipped with an improved carburetion system of the present invention. The fuel efficiency was measured and the results are shown in Table I (line C) . During the test it was noted that the C ₅ -C ₁₀ fuel easily started and ran the engine equipped with the improved carburetor even though the fuel had a Reid Vapor Pressure of only 6.

While the present invention has been described terms of certain preferred embodiments and exemplified wi respect thereto, one skilled in the art will readi appreciate that variations, modifications, change omissions and substitutions may be made without departi from the spirit thereof. It is intended, therefore, th the present invention be limited solely by the scope of t following claims: