Abstract:
A rotary valve is disclosed suitable for replacement of poppet valves. The valve is temperature controlled through a combination of heat transfer techniques and means for reducing heat transfer between gas flows and the valve components. Assymetric geometry is used in the seals to reduce wear and friction, and a removable combustion chamber in the valve housing is used to facilitate fabrication, servicing and performances. A prototype of the valve was developed for a 30 cubic inch displacement four-stroke spark-ignition engine. The gas seals and lubricated parts of the rotary valve have been found to remain below 400 degrees Fahrenheit during test runs wherein the valve controlled gas flows and has maintained a brake mean effective pressure of 108 to 121 psi for periods of up to an hour. 
     The valve uses pure rotation, and can be dynamically balanced for operation to the peak RPM permissible with reciprocating pistons. A four-stroke engine converted to rotary valving needs very few parts. For example, a four cylinder automotive engine fitted with a spheroidal rotary valve system requires only 11 moving parts; namely a crankshaft, pistons and rods, the valveshaft and a timing belt to drive the valveshaft. The valve is applicable to new engine production and is also suitable as a cylinder head assembly for retro-fit to existing engines of the overhead camshaft type.

Description:
REFERENCE TO PRIOR APPLICATIONS 
     This utility patent application is filed with reference to a provisional application entitled: Spheroidal Rotary Valve for Combustion Engines filed at the USPTO on Aug. 25, 1997 and Ser. No. 60/057,354. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to rotary valves for use with internal combustion engines. It relates further to means for cooling rotary valves and other rotary mechanisms. It relates still further to the lubrication of rotary valves. It also relates to rotary valves having a spherical shape or a shape which is similar such as an ovoid, obloid, ellipsoid, parabaloid, ball, globular and so forth. This group of shapes will be referred to herein as spheroidal. 
     2. Background of the Invention 
     Valves known to be suitable for internal combustion engines may be classified according to both their action, which may be either lifting or sliding, and their motion which may be classed either as oscillatory or continuous. The conventional poppet valve for example has lift action and its operation requires oscillatory motion. The sliding action valve however may be designed to operate either with oscillatory motion or with a continuous motion provided by rotation, the latter valves being classed as rotary. 
     During development of the combustion engine, inventors have sought a continuous motion to improve on the oscillatory poppet with its speed limitations, complexity, cost, and in some cases, noise. In the prior art, an estimated 2,000 patents may be found which relate to novel rotary valves for use on an IC engine. Of these, approximately 70 patents, including both U. S. and foreign, may be found which relate to spheroidal valves. The following have relevance to the invention herein. 
     Charles G. Wridgway, an Englishman, in U.S. Pat. No. 942,124 issued Dec. 7, 1909 fully describes application of a spheroidal valve to an IC engine. The ingenuity and limited claims of Wridgway&#39;s invention suggests that earlier art existed when he applied Dec 31, 1908. His use of a single valve rotor to valve two adjacent cylinders of an engine has considerable merit however and was apparently used in the cylindric valved Itala engines. 
     M. G. Chandler in U.S. Pat. No. 1,080,892 issued Dec. 9, 1913 describes a spherical rotary valve with a peripheral port and fixed sealing ring. It is not known whether Chandler&#39;s valve worked, as no split is shown or described in the circular seal used to seal combustion pressure against the sphere. If no split was used and thus no possibility for radial expansion of the ring under gas pressure, the valve seal would have leaked, probably making the engine inoperable. If Chandler did use a split seal, the rotary valve engine would probably have operated well for several minutes. Provision for cooling however appear to be insufficient. Therefore, if run at any appreciable power output, the valve rotor would have overheated. Chandler does not describe any necessity for specifically cooling the seal. His valve also appears to have contacted the casing over its entire surface which would have created problems. 
     Jan Zeeman in U.S. Pat. No. 1,868,301 issued Jul. 19, 1932 discusses the need to regain the explosive gas-mixture left in the valve chambers after the inlet (stroke) and a method for accomplishing it. No special control of the scavenging flow is described. 
     Jean-Claude Fayard in U.S. Pat. No. 4,606,309 issued Aug. 19, 1986 describes a method of scavenging wherein the inducted mixture is leaned out towards the end of the inlet stroke. Fayard&#39;s method and end result both differ from the scavenging described herein. 
     The prior art regarding gas sealing indicates that other inventors consider the seal situation workable but not perfected. The variety of recent patents issued on seals for a rotary valve indicate that other inventors have not finalized a workable seal arrangement. 
     Metered lubrication is a straight forward mechanical engineering problem. However known metering methods that allow control of oil flow are complicated and expensive. No prior art could be found re a metering system as described herein. 
     Cooling methods were found for a rotary valve such as the following: 
     1) Flowing coolant through a hollow rotor shaft and through the rotor, 
     2) Flooding the rotor surface with coolant and re-collecting the coolant, 
     3) Spraying water through the hot rotor port, 
     4) Conducting heat out to a pad or a portion of the rotor casing held tightly against the rotor, the pad or casing portion being cooled. 
     James I. Thompson in U.S. Pat. No. 880,601 issued Mar. 3, 1908 for example clearly describes a frusto-conical valve for the combustion chamber of a gas engine and teaches a method for flowing water or air coolant through the valve. Other patents describe internal coolant flow through rotary cylindric and spheric valves. Due to the need for at least one rotary seal in the valve shaft for liquid coolant, these cooling methods cannot achieve the high reliability and low cost of contemporary poppet valve art. 
     E. Ballou in U.S. Pat. No. 1,018,386 issued Feb. 20, 1912 describes a rotary valve having double curvature and includes ovoids and ellipsoids. Ballou does not elaborate and gives no specific preferred shapes, no reasons for using such shapes in lieu of spherical shapes, and no suggestions for engineering such shapes into a valve. No detail was given regarding the amount of double curvature desired and very little was said as to the improvement obtained on valve operation by its use. Ballou&#39;s non-spherical shapes appeared to be merely concepts, with very little taught about their benefit or method of use. 
     J. J. Genet in French Patent # 970,264 issued Jan. 2, 1951 discusses ellipsoidal and ovoidal shapes for a rotary valve rotor. However, he does not describe how such shapes should be designed and used in a valve nor what purpose they serve, and he provides no drawings. Genet&#39;s non-spherical shapes do not appear to be sufficiently well taught for someone skilled in engine art to understand their purpose or to understand how to apply them to an engine and obtain a benefit over the use of a spherical valve, since even the spherical shape is almost unknown except in the world&#39;s patent files. 
     D. F. Browne in U.S. Pat. No. 4,821,692 issued Apr. 18, 1989 describes a spherical valve rotor rotatable and offsetable in a spheroidal casing to obtain better sealing. Browne&#39;s invention was determined to be geometrically different from my invention described herein. 
     Albert E. Moorhead in U.S. Pat. No. 1,218,296 issued Mar. 6, 1917 describes a spherical valve rotor using a through port insulated from the surface by a filling of asbestos or other insulating material. The insulated port alone is therefore old art. The “through port” valve of Moorhead&#39;s has approximately three times the surface area of a peripheral port and would collect three times as much heat from the exhaust. It would be difficult to keep such a valve properly cool. 
     F. A. Wyczalek et al in U.S. Pat. No. 3,965,681 issued Jun. 29, 1976 describes a metal liner in an engine exhaust port, the purpose being to carry the hot exhaust gas more efficiently to an exhaust turbine. This is in effect an insulating liner in the port with no attempt to conduct heat downstream and away from the cylinder head. 
     Some two-stroke engines are now being manufactured with auxiliary rotary inlet or exhaust valves placed in series with piston valved ports on the cylinder walls. These valves aid in timing gas flows in a two-stroke engine and in such application, they withstand only a few pounds per square inch, their designs being inadequate for the thousand pounds per square inch of a combustion chamber. 
     No prior art was found describing the art of cooling a rotary valve as is taught herein. No mention was found regarding the control or metering of oil to a rotary valve. 
     SUMMARY OF THE INVENTION 
     The valve invention herein is an improvement on the rotary valves of the prior art. The improvement is achieved by a combination of elements which must be used together for maximum effect. These include means to reduce heat input into a spheroidal rotary valve, means to distribute heat and conduct it through the valve, and means to conduct heat out of the valve. Most of the described elements are required in a valve used on a high output (BMEP&gt;100 psi) engine. 
     For the valve to be practical, it also requires controlled lubrication, and for economical operation this requires metering. An oil metering system with output that correlates with RPM and IMEP is therefore included. It can be built either into the valve body or into an adjacent bearing which carries the valve. 
     An insert type sleeve bearing with pressure oil feed, self contained seals and associated oil drains at each end and a built in oil release port was devised. It serves to control potential oil loss to the valve casing space from the multiplicity of bearings needed along the rotor shaft. 
     A scavenging mechanism is described which retrieves fuel-air charge that gets trapped in the rotor port. 
     Since these separate innovations all contribute to making the rotary valve a practical mechanism, they are being described here and submitted in a single application. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     FIG. 1 is a sectional view parallel with the axis of a spheroidal rotary exhaust valve and associated oil metering mechanism. 
     FIG. 2 is a sectional view perpendicular to the axis of a spheroidal valve illustrating oil metering mechanism and drive means for the valve from engine crankshaft. 
     FIG. 3 is a sectional view of a spheroidal rotor showing rotor drive, torsional damping means, oil metering means, and insert bearing. 
     FIG. 4 is a view partly in section, of a spheroidal valve casing with rotor removed, showing a gas seal, oil wiper strips arranged to divert oil away from the ports, and thc exhaust port. 
     FIG. 5 is a graph of exhaust gas temperature versus compression/expansion ratio of an engine. 
     FIG. 6 is a partial view in section of a metering mechanism with split ring valve. 
     FIG. 7 is a perspective view of a split ring metering valve. 
     FIG. 8 is a planform view of the circular sealing ring of FIG. 10 taken on line  8 — 8 , the ring being formed into an oval by an oval containment groove. 
     FIG. 9 is a spherical valve in section showing relief at the leading edge of the rotor port. 
     FIG. 10 is a planform view of the valve of FIG. 9 taken along line  10 — 10  and showing reliefs along the sides of the rotor port. 
     FIG. 11 is a planform view of a shaped sealing ring. 
     FIG. 12 is a sectional view of the scaling ring of FIG.  11 . 
     FIG. 13 is a planform view of a non-uniform spring for use under a sealing ring. 
     FIG. 14 is a sectional view of the spring of FIG.  13 . 
     FIG. 15 is a perspective view of an elongated rotor in combination with a circular heat transfer member. 
     FIG. 16 is a sectional view along line  16 — 16  of FIG.  15 . 
     FIG. 17 is a perspective view of an ellipsoidal valve rotor. 
     FIG. 18 is a sectional view along line  17 — 17  of FIG.  17 . 
     FIG. 19 is a sectional view of a rotary valve with means for scavenging the rotor port and alternative sources for the scavenge gas. 
     FIG. 20 is a partial cross sectional view along line  20 — 20  of FIG. 19 illustrating specific scavenging within the rotor port. 
     FIG. 21 is a sectional view of a hollow spheroidal rotor containing an internal coolant. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As illustrated in FIG. 1, a spheroidal rotary valve  10  described herein is suitable for controlling, with a single valve unit, both the intake flow  12  and exhaust flow  14  of an internal combustion engine cylinder  16  operating at BMEP&#39;s above 100 psi. A spheroidal valve rotor  18  is shown mounted on valve shaft  90  for rotational operation within cavity  19  defined by cylinder head  80 . In typical use, valve  10  is operated by drive means from the engine&#39;s crankshaft. One well known drive means is shown in FIG. 2 comprising a toothed timing belt  122  driving a sprocket  124  attached to valve shaft  90  wherein a four stroke cycle engine is operated with valve rotor  18  turning at one-half crankshaft speed. 
     Also shown in FIG. 1 is a novel construction for cylinder head  80  containing rotary valve  18 . Head  80  is made in two parts comprising a cap  84  which bolts to casing  42  which in turn bolts to cylinder block  86 . Parting plane  88  between the cap and casing is on a diagonal so as to allow exhaust port  78  to lie entirely within the casing and inlet port  94  to lie entirely within the cap. Since almost no heat enters the cap from the inlet port or from other sources, the cap needs no cooling. The casing, on the other hand contains the exhaust port, a major source of heat, as well as casing insert  40 , another source of heat. Thus, the casing is fitted for cooling such as the liquid cooling illustrated. Another advantage of the diagonal split is that inlet and exhaust ports can each be entirely within either the casing or in the cap, and their integrity is not affected by the presence of the necessary parting plane for assembly of the valve shaft and rotors which typically run along parallel with a bank of an engine block. 
     An exhaust heat extractor  96  is illustrated in exhaust port  78  which extractor has an insulating liner to allow exhaust heat to continue downstream without too much transfer to the walls of the extractor. Heat which does reach these walls conducts out to air fins  98  where it is dissipated into the atmosphere, thereby allowing valve rotor  18  to run cooler. 
     Insulation  100  is also placed on the inside spherical surface of casing  42  in a region adjacent the exhaust port  78 . This insulation reduces the heat absorbed from spilled exhaust flow during the exhaust blowdown and exhaust stroke of the engine. 
     Also shown in FIG. 1 is that coolant flow  100 ′ is directed directly against structure supporting sealing ring  34  where it is passed over by exiting exhaust gas. This portion of ring  34  receives the most exhaust heat and therefore should receive the most intense cooling. 
     Although illustrated with both an inlet and an exhaust port, valve  10  is also suitable for individual control of either the exhaust flow or the inlet flow of an engine. The gist of the invention is a combination of elements which together make a rotary valve practical. 
     One group of elements reduces heat input into the valve rotor  18 . A higher compression ratio than standard is used in the engine combustion chamber  20  to reduce the exhaust temperature, a higher ratio than can be used in a conventional engine chamber wherein the exhaust valve is a hot spot which can precipitate pre-ignition or detonation. The rotary valve runs cool at about the same temperature as the engine cylinder wall, leaving the spark plug tip as the only hot spot remaining in the chamber. The reduction in exhaust gas temperature that is obtainable is given in the graph of FIG.  5 . 
     Second, a peripheral port  22  is used in the spheroidal valve rotor. The alternative would be a “through port” which enters and exits the rotor surface. A through port however presents about three times as much surface area to the gas flows and would absorb excessive heat from the exhaust. 
     With reference to FIGS. 1 and 4, the opening end  24  of the rotor port and the opening end  26  of the chamber port are both shaped (squared off) to complement each other in producing quick opening and rapid release of exhaust gas. Rapid release reduces heat transfer to the valve rotor. Quick closure of the exhaust port is also desirable to switch to the inlet phase of the gas cycle. 
     As shown in FIGS. 1 and 21, the rotor port  22  contains a liner  56  to effect thermal insulation and reduce heat flow into the bore  30  of the rotor port  22  and on into the rotor  18 . Liner  56  may be a sheet of refractory material fixed in place in port  22 . An interface created between liner  56  and bore  30  in the body of the rotor serves as effective thermal insulation, although additional insulation such as a sheet of thin refractory metal e.g. stainless steel foil may be advantageous. 
     Another element needed in the valve is cooling and with reference now to FIGS. 1 and 2, a cooling mechanism is built into valve  10 . Provision is made for heat absorbed in the vicinity of port  22  to travel across rotor  18  and transfer as per arrows  54  to rotor sealing ring  34 . From the sealing ring, heat transfers to the outer wall  36  of groove  38  which contains sealing ring  34 , groove  38  being defined either a casing insert  40  as illustrated in FIG. 1, or by casing  42  itself itself as illustrated in FIG.  2 . From this outer wall  36  of groove  38 , heat is conducted to a means for cooling such as coolant duct  44  in FIG.  1 . Most of the heat entering casing  42  enters in a rotor sealing ring  34  towards exhaust port  78 , this band having a width equal to that of rotor port  22 . To prevent overheat (a temperature in excess of 400 degrees F at which temperature conventional engine oils begin to decompose rapidly) in this band and portion of rotor sealing ring  34 , fresh coolant  82  is directed into annular duct  44  immediately adjacent rotor sealing ring  34  and exhaust port  78  before the coolant has received heat from other parts of the engine. 
     To carry additional heat away from rotor  18  and base of casing  42 , a heat extractor  96  made of high thermal conductivity metal (such as a relatively pure copper alloy) conducts heat from the rotor end out away from the engine where it is dispersed to the air by air fins  98 . An internal lining of thermal insulation  76  reduces the heat transferred to extractor  96  and allows more heat to pass out with the exhaust. An additional exhaust heat load is placed on casing  42  at cavity wall  100  and  100 ′ just above and below the exhaust port. This heat load is avoided by thermal insulation  102  applied to the cavity wall in an area around exhaust port  78 . A suitable construction and a preferred embodiment for cylinder head  80  containing rotary valve  10  is to divide said cylinder head into a base  42  which bolts to engine block  86  and a cap  84  which bolts to the base  42  at parting plane  88  which plane  88  also includes the axis of valve shaft  90 . By making the parting plane at a sharp angle with the base cylinder head joint  92 , it is possible to confine coolant  82  and exhaust port  78  and most of the valve heat within base  42 . Similarly, the inlet port(s)  94  may be confined to cap  84 . 
     When gas pressure is high in combustion chamber  20 , rotor sealing ring  34  is forced into high pressure contact with rotor  18  and with casing  42  (or insert  44  depending upon which construction is being referred to). Rapid thermal transfer therefore occurs from the rotor to the casing during these periods of high gas pressure which pressure pulses are created each time combustion takes place in the gas cycle. 
     Internal heat transfer in the valve rotor carries the rotor port heat across to the area of the rotor surface which bears the high gas pressure indicated by arrows  58  illustrated in FIG. 2 during and immediately following combustion in the engine. Internal heat transfer is enhanced if the core  46  of rotor  18  is made of a material having high thermal conductivity such as aluminum. Aluminum can be used as the surface material for rotor  18  and bearing surface for seal  34  in which case an Al casting alloy such as Type A390.0 (having 17% Si and 4.5% Cu) or 393.0 is preferred. 
     An alternative and preferred embodiment is illustrated in FIG. 3 wherein rotor  18 ′ is bimetallic with a core  46  of a high thermal conductivity material such as aluminum covered with a good wearing surface metal  48  such as a high Brinell hardness cast iron. 
     Another alternative for conducting heat across the rotor is illustrated in FIG. 21 wherein rotor  18 ″ is hollow and contains a heat transferring liquid  50  which may be sealed into the rotor by plug means  52 . Liquid  50  may be a vaporizable liquid such as an alcohol which can transfer heat by vaporization at the area of heat input and condensation at the area of heat removal, or a liquid such as an oil or a liquid metal (e.g. Hg or Na) which can flow or splash around and carry heat with it. In this embodiment, the preferred rotor material is a high strength cast iron which can be accurately cast in thin sections. 
     Referring now to FIGS. 1 and 2, lubrication is required for the rotor sealing ring  34 , which is the only required contact between rotor  18  and casing  42 . Referring to FIG. 2, rotor  18  is supported by valve shaft  90  which runs on journal bearings at  62  and  62 ′. These bearings may be machined directly in casing  42  as in FIG. 2, or composed of insert bearing shells  106  as in FIG.  3 . Oil is supplied to the bearings by an oil duct  108  and feed duct  110 , or via a hollow valve shaft  90 ′ and radial feed holes  116  which pass oil through the shaft to the bearing shells. Oil is returned from oil seals  112  at each end of each bearing shells  106  via pickup ducts  118  to a common duct  120  from which oil is returned to the engine. 
     An oil metering method and system  60  operates from high pressure pulses developed in an oil film  64  which supports rotor  18  in journal bearings  62  and  62 ′ within casing  42 . These pressure pulses result from gas pressure pulses illustrated by arrows  58  in FIGS. 2 and 3, which cause mechanical pressure pulses  59  from valve shaft  90  against oil film  64 . Each pressure pulse in film  64  pumps a minute amount of oil up duct  66 ′ past pressure relief valve  68  into lubricant distribution ducts  70  and  72 . Relief valve  68  may typically be a ball held on a seat by a spring. 
     From duct  70 , oil is spread onto the rotor in a thin film by wipers such as  74  in FIG.  1  and  74 ′ shown in FIG.  4 . Wiper  74  is a circular split ring. Wipers  74 ′ are spring loaded segments of a ring arranged to divert oil away from the ports. 
     Another embodiment of the oil metering system is illustrated in FIG. 3 wherein oil flow  91  from  20  the core of valve shaft  90 ′ flows radially out through port  116 ′ and fills oil film  64 ′ between rotor  18 ′ and valve shaft  90 ′. Oil film  64 ′ is sealed in between the rotor and the shaft by oil seals  126  at each end of the rotor. Arrows illustrating gas pressure  58  on rotor  18 ′ create pressure  59 ′ on oil film  64 ′ ejecting oil from the film out duct  66 ′ to pressure relief valve-V  68 ′ and thence thru distribution ducts  70 ′ within rotor  18 ′ to the surface of the rotor. 
     Another embodiment of the oil metering mechanism is illustrated in FIGS. 6 and 7 wherein valve shaft  90  pumps oil up duct  66 ′ to pressure relief valve  68 ′ which comprises a split tubular spring  136  located in a cylindric valve seat  138 . Oil pressure collapses spring  136  slightly allowing oil to meter past it and feed out of the valve  68 ′ as per arrow  140 . 
     To facilitate assembly of the rotary valve, valve shaft  90 ′ in FIG. 3 defines a groove  128  which aligns with a groove  130  defined by the internal diameter  134  of valve rotor  18 ′. A pin  132  is fitted into these grooves  128  and  130  to provide rotary drive for the rotor. In addition, an oil film created between pin  132  and the two grooves provides torsional damping for the valve shaft. In the case of a multi-cylinder valve assembly having up to eight possible valves on a single shaft, such damping is desirable. 
     To reduce friction and wear between rotor sealing ring  34  and rotor  18  as shown in FIG. 1, several geometric modifications are available. In FIG. 8, a planform view of a rotor sealing ring  34  is shown with an oval form due to being fitted into an oval groove, not shown. The groove compresses seal  34  by a few thousandths of an inch (for a rotor with a diameter of about 3″) as per arrows  142  to create the oval shape. This ovality causes the seal to bear more heavily on the rotor along its sides between a and d and between b and c, and less heavily on the rotor periphery which bears between a and b and between c and d. 
     Another method of reducing friction and wear on the seal is to chamfer the rotor. In FIGS. 9 and 10, a peripheral chamfer  144  of roughly a thousandth of an inch is blended into the rotor spherical periphery surface at the closing end of port  22 . Chamfer  144  will reduce a tendency of the resilient sealing ring  34  to hook on the closing end of the rotor port as it approaches. A resilent sealing ring will also tend to droop into port  22  when the port is open. This causes the seal to wear at the edges of port  22 . To counteract this, side chamfers  146  are blended into the rotor surface, again on the order of a thousandth of an inch for a 3″ diameter rotor. 
     A third embodiment for reducing wear and friction is to assymmetrically shape the sealing ring  34 ′ as illustrated in FIGS. 11 and 12. The sides of the ring  148  are slightly wider than the peripheral surfaces  150  to achieve a disparity in pressure between the sides which bear on the rotor adjacent its bearings, and the peripheral surfaces  150  which bear on the rotor peripheral surface and are crossed by the rotor port. Due to asymmetry in sealing ring  34 ′, it is preferably pinned to ensure that it is initially aligned and remains with the rotor&#39;s plane of rotation. 
     Another embodiment to reduce wear and friction on the sealing ring is illustrated in FIGS. 13 and 14. In this element, a spring  152  which is placed under sealing ring  34  in groove  38  or  38 ′ such as in FIGS. 1,  2 , and  3  is designed to have non-uniform tension around its periphery. With a wire spring or a thin metal spring, this tension variation may be achieved by varying the spacing between kinks  155  formed in the circumference, as illustrated. To achieve the desired disparity in force on sealing  34  between sides and periphery p, the kinks  153  are placed more closely along the sides of spring  152 . 
     Another embodiment to provide a disparity between sealing ring pressure between the ring sides and periphery is illustrated in FIGS. 15 and 16. In this embodiment, rotor  18 ′, rotating as per arrow R, is spheroidal and elongated in the direction of its rotational axis whereby it bears on sealing ring  34  more heavily along its sides  156  (adjacent the bearings) than it does over its peripheral band or region  158  denoted by dashed lines. This elongation need only be slight on the order of a few mils difference between axial and peripheral diameter for a 3″ rotor, dependent upon the degree of disparity desired in pressures on the sealing ring. When no gas pressure is forcing the ring against rotor  18 ′, it will ride with a slight clearance  178  at the periphery of the rotor. Under gas pressure from the engine combustion chamber, resiliency of sealing ring  34  allows it to deflect into dashed position  180  and fit tightly against rotor  18 ′. 
     Referring now to FIGS. 17 and 18 rotor  18 ″ is formed as an ovoid or ellipsoid whereby the peripheral diameter  160  is greater than the axial diameter, not shown. The sealing ring  34 ′ to fit and seal against this rotor will typically approximate an ellipse, although other shapes can of course be devised. With an ellipsoid ratio on the order of 1.5:1 or greater, the size and associated breathing capacity of port  22  can be increased by 50% or more, with no major disadvantages. 
     Port  22  of rotary valve  10  has an inherent characteristic of carrying a trapped volume of inlet gases around to the exhaust port and losing these gases to the exhaust flow. In a Diesel, this would not present a problem since no fuel is in the inlet flow. In an Otto cycle engine, fuel is presently present in the inlet flow and in this case will be lost. To prevent or greatly reduce such loss, a scavenging mechanism has been devised as illustrated in FIGS. 19 and 20. In normal engine operation, after rotor  18  has passed the inlet phase and port  22  is in the position of FIG. 19, inlet gases are trapped in port  22 . At the rotation position shown, duct  162  passing through casing  42  is uncovered by the opening edge  24  of port  22 . Scavenge gas now enters from duct  162  fed from scavenge gas feed line  170  and fills port  22  forcing the trapped inlet gases as per arrows  164  back into the inlet manifold, not shown. A control valve  172  may be used to adjust gas flow to the scavenge duct  162  in correlation with engine throttle opening and RPM. Scavenge gas or air may also be used, with suitable control, for leaning the inlet gas mixture. 
     Various scavenge gases may be used, the most convenient being ambient air. Ambient air will however not scavenge well once the inlet manifold pressure nears atmospheric which it will do near full throttle operation. Modern automotive engine often have an air compressor used to feed a catalytic convertor. Air could be obtained from the same air pump. Alternatively, exhaust gas can be used as the scavenge gas and is available at slightly over atmospheric pressure if captured in the exhaust port  78  where it is struck by the initial blowdown gas when the exhaust first opens, as located at entrance duct  166 . For maximum power output from the engine, the exhaust gas used for scavenge should be cooled as by intercooler  168  located in alternative gas feed line  170 ′. 
     To promote scavenging efficiency and maintain cleanliness of the port walls, duct  162 ′ as shown in FIG. 20 may be divided or so shaped to produce a gas jet into port  22  which scrubs and scours the walls  174  of port  22 . 
     FABRICATION AND TESTS 
     Fabrication of a spherical valve was simplified in that the sphere and its socket are each definable by a single dimension, the diameter. A 1972 Ford Pinto engine was used as a test bed, and the front cylinder used for experiments while the other cylinders were disabled. Prototype cylinder head were mounted on the block, which provided a 3.55″ bore cylinder with a 3.0″ stroke and a displacement of about 30 cubic inches. The crankshaft driven timing belt provided synchronized drive for the rotary valve shaft. 
     For the first prototype, a 2.75″ diameter carbon steel rotor was used and a cast iron sealing ing of 2.0″ diameter with a thickness of 0.050″. A spring under the ring was found to be useful but certainly not essential, as runs of an hour were made without it. A casing was fabricated from aluminum which served also to define the groove for containment of the sealing ring. 
     A satisfactory gas seal was obtained in the first spherical valve prototype and gave good performance for test periods up to about five minutes after which it overheated. Water cooling was then applied to the gas seal, producing workable cooling. The addition of an insulating liner to the rotor port provided the next major gain in control of rotor temperature. Subsequent tests were then run for multiple periods of an hour each with excellent control of temperature. 
     Metering was developed and ultimately reduced to a measured oil usage of less than one quart per 1,100 mile equivalent in a Pinto, extrapolating from the single cylinder test engine operating at between 1,500 and 2,000 crankshaft RPM. Oil seals for the valve shaft bearing were developed until their oil leakage into the valve casing was undetectable. Wear on the sealing ring was ultimately reduced to a negligible level.