I11111 111111ll111 Ill11 Ill11 US005908016AIIIII IIIII Ill11 IIIII Ill11 IIIII 11ll11111111111111 United States Patent [19] [ill Patent Number: 5,908,016 Northam et al. [45] Date of Patent: Jun. 1,1999 CARBON FIBER REINFORCED CARBON 4,894,286 111990 Gray ........................................ 4281408 COMPOSITE ROTARY VALVES FOR 4,909,133 311990 Taylor . INTERNAL COMBUSTION ENGINES 5,052,349 1011991 Buelna ................................. 1231190.6 5,083,537 111992 Onofrio et al. Inventors: G. Burton Northam, Carrollton; Philip 5,154,147 1011992 Muroki 1231190.4 5,255,645 1011993 Templeton ........................... 1231190.4 0. Ransone, Gloucester; H. Kevin 5,315,969 511994 Macmillan ........................... 1231190.6 Rivers, Hampton, all of Va. 5,370,087 1211994 Guimond et al. 5,490,485 211996 Kutlucinar ........................... 1231190.4 Assignee: The United States of America as 5,524,579 611996 Eluchans .............................. 1231190.6 represented by the Administrator of 5,526,780 611996 Wallis .................................. 1231190.6 the National Aeronautics and Space 5,536,574 711996 Carter ...................................... 4281381 Administration, Washington, D.C. 5,654,059 811997 Hecht ..................................... 428165.9 Appl. No.: 08/812,826 Primary Examinerarick R. Solis Attorney, Agent, or Firmxurt G. Hammerle Filed: Mar. 6. 1997 [571 ABSTRACT Related U.S. Application Data Carbon fiber reinforced carbon composite rotary, sleeve, and Provisional application No. 601013,306, Mar. 6, 1996. disc valves for internal combustion engines and the like are disclosed. The valves are formed from knitted or braided or Int. C1.6 ........................................................ FOlL 7/16 warp-locked carbon fiber shapes. Also disclosed are valves U.S. C1. .................................... 123/190.17; 1231190.8 fabricated from woven carbon fibers and from molded Field of Search .............................. 1231190.1, 190.4, carbon matrix material. The valves of the present invention 1231190.6, 190.8, 190.17 with their very low coefficient of thermal expansion and excellent thermal and self-lubrication properties, do not References Cited present the sealing and lubrication problems that have U.S. PATENT DOCUMENTS prevented rotary, sleeve, and disc valves from operating efficiently and reliably in the past. Also disclosed are a 975.777 10/1934 Bournonville ....................... 1231190.6 sealing tang to further improve sealing capabilities and 4:010:727 311977 Cross et al. .......................... 1231190.4 anti-oxidation treatments. 4,370,955 211983 Ruggeri ................................ 1231190.6 4,683,809 811987 Taylor . 4,736,676 411988 Taylor . 2 Claims, 5 Drawing Sheets US. Patent Jun. 1,1999 Sheet 1 of 5 5,908,016 18 1 I 16’ I I I I I I 1J FIG. 1 FIG. 2 US. Patent Jun. 1,1999 Sheet 2 of 5 5,908,016 50 49 4841s Jf 45 FIG. 3 44 43 41 51 44 47q4eJ 48 45 f FIG. 4 US. Patent Jun. 1,1999 Sheet 3 of 5 5,908,016 62 - 72 69 FIG. 5 US. Patent Jun. 1,1999 Sheet 4 of 5 5,908,016 83 83 -90 83 -83 -84 85 -82 \ 90 -81 / 86 89 FIG. 6 us. Patent Jun. 1,1999 Sheet 5 of 5 5,908,016 I FIG. 8 5,908,016 1 2 CARBON FIBER REINFORCED CARBON noisier valve trains. More efficient and powerful and quiet COMPOSITE ROTARY VALVES FOR engines could be designed if a satisfactory alternative to the INTERNAL COMBUSTION ENGINES poppet valve could be found. Another inherent problem with poppet valves is the fact CWMOF BENEFIT OF PROVISIONAL 5 that they stand directly in the path of the intake and exhaust APPLI CAT1ON charges they are meant to admit and discharge. Over the years almost every variation in combustion chamber shape, Pursuant to 35 U.S.C. 5 119, the benefit of priority from valve position, and manifold design has been tried to maxi- provisional application Ser. No. 601013,306 with a filing mize the amount of charged fuel that can flow past a poppet date of Mar. 6, 1996, is claimed for this non-provisional valve into the chamber. The current trend has been to give application. the intake charge (and, to a lesser extent, the exhaust charge as well) as straight a path as possible into the combustion ORIGIN OF THE INVENTION chamber. Nevertheless, the poppet valve still stands in the The described invention was made by employees of the way. The ability of an engine to admit a charge efficiently United States Government and may be manufactured and 15 could be significantly improved if an unblocked path into the used by the government for government purposes without combustion chamber could be designed. the payment of any royalties thereon or therefor. Another inherent problem with metallic poppet valves is that they quickly lose strength as temperatures increase. BACKGROUND OF THE INVENTION Low cost, commodity steel poppet valves used in the over- 2o whelming majority of combustion engines are limited to 1. Technical Field exhaust gas temperatures in the 1500 to 1750 degree Fahr- This invention relates to rotary, sleeve and disc valves enheit range. Combustion efficiencies could be improved made of carbon fiber reinforced carbon composite materials, and undesirable emissions reduced if exhaust gas tempera- for use in internal combustion engines and the like. tures could be raised beyond this level. 2. Description of the Related Art 25 Over the years engineers have proposed the use of rotary, Current internal combustion, 4-cycle engines use metal sleeve, and disc valves to overcome the inherent limitations poppet valves. While 2-cycle engines still use reed, disc, and of the poppet valve. The basic design of these valves is to rotary valves, stricter air pollution standards are causing rotate a valve body to expose and close intake and exhaust manufacturers to turn to poppet valves even for these ports. In this way, the need to reciprocate a poppet valve is engines. Most poppet valves are cast, forged, or machined 30 avoided. There are three very general designs of rotary from billets of metal. These valves are inherently heavy and valves: cylindrical, sleeve, and disc. One type of cylindrical have poor structural properties at higher temperatures. By rotary valve is open at each end and separated inside by a design, poppet valves must reciprocate: starting from a full wall, creating two chambers, each ported to the combustion stop and accelerating to very high speeds, only to be brought chamber through windows in the side of the cylinder. to a stop again and reaccelerated and brought again to a stop 35 Another type of cylindrical rotary valve is substantially solid at the place it started. Due to their significant mass, metallic and has in its sides one or more recesses that expose the valves develop substantial inertia as engine speed combustion chamber to a manifold. These two types of (revolutions per minute or “RPM”) increases. Almost all cylindrical rotary valves have axes of rotation that are production poppet valves are restrained by metallic springs. perpendicular to the cylinder. Another type of rotary valve However, as RPM increases, the spring’s ability accurately 40 has its axis of rotation parallel to the cylinder. One such type to restrain the poppet valve’s travel is overwhelmed by the is in the general shape of a cone, the base of which is valve’s inertia and it “floats”. This tendency to float inhibits exposed to the combustion chamber. A port from the base the engine’s ability to reach higher RPM, where more power and through the side of the cone permits gases to be admitted can be produced more efficiently. or expelled. The sleeve valve is in the shape of a cylinder Over the years, many poppet valves have been designed 45 and also acts as the cylinder in which the piston reciprocates. to control valve motion, even at high RPM. Ducati The sleeve valve rotates, and in some cases also Mechanic, Spa., the Italian manufacturer of road and racing reciprocates, exposing ports. The disc valve can operate in motorcycles, uses a fully mechanical poppet valve opening substantially the same manner as the cone-shaped rotary and closing, “desmodromic” system. The efficacy of this valve, or it can operate at different positions, such as at the design has never been conclusively established and it is an so side of the cylinder, as is the general practice with 2-cycle extremely expensive system to manufacture and maintain. disc valves. Rotary valves in 4-cycle engines have never Electrically operated poppet valves are currently being seen volume production. Sleeve valves have been used in tested, but they have not yet been shown successfully to production aero engines, but have never gained wide favor. operate at even moderately high RPMs. International For- The principal of these valve designs is that the rotary mula 1 racing teams have in recent years employed pneu- 5s valve and the surface it rides in must be very closely mated matic springs to overcome the limitations of metal springs. in order adequately to seal the combustion chamber, but as It is not clear when or if these designs will be put into engine temperatures rise the different expansion rates of production engines, but it will be recognized that these these metallic parts leads either to sealing problems, if the systems do not avoid the basic problem: poppet valves must parts are not close enough, or to seizure, if they are too close. reciprocate. 60 An additional defect of these designs is that they are difficult In production engines, the tendency of poppet valves to to lubricate and when they are adequately lubricated they float is compensated for by the use of increasingly stiff tend to admit lubricating oil into the combustion chamber, springs. However, increasing spring stiffness also increases leading to undesirable emissions. Moreover, if a metallic the work the engine must perform just to open the valves, rotary valve is used to discharge exhaust gases it will tend and this in turn results in significant power drain.