Patent Publication Number: US-7713042-B1

Title: Rotary engine

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   None 
   BACKGROUND 
   1. Field of the Invention 
   This invention relates to rotary engines powered by compressed air or steam, specifically to a rotary engine using compressed air or steam that produces power more advantageously than a combustion engine. The most preferred embodiment of the present invention rotary engine has a two-part casing that houses a rotor having three equally spaced-apart vanes/pistons (hereinafter referred to as pistons without intent of limitation) secured to the rotor via slots. During use of the present invention, the rotor and its three vanes are its only moving parts. Also, the casing fits closely around the rotor and pistons, which are centered within the casing. In addition, the free ends of the pistons are angled to form a tip, and each piston further contains an internally positioned spring that biases the angled piston tip against the interior surface of the casing to create a reactionary force upon start up. The pistons divide the interior space within the casing into three working chambers, and each revolution of the rotor within the casing produces three power strokes. The pistons are hollow and receive high pressure steam or compressed air from a center fixed valve having two inlet ports in opposed positions from one another. Thus, as the pistons rotate within the casing, injection of high pressure steam or compressed air into each piston occurs twice during one revolution of the rotor. Each piston also contains an opening adjacent to its angled free end through which the high pressure steam or compressed air used to produce power is delivered into the working chamber behind it. The delivery/end openings in all pistons are identically oriented away from the direction of rotor rotation. 
   The interior surface of the present invention casing has two arcuate lobes separated by two opposed flattened areas across which the pistons also move during their rotation. Furthermore, two exhaust ports are formed through the casing in opposed positions, each adjacent to a different one of the flattened areas and in a location that allows each piston to move across it prior to reaching the adjacent flattened area. Shortly after a piston passes one of the flattened areas and before the piston ahead of its has moved across the next approaching exhaust port to open it, the piston passing the flattened area will advance into a position where it is in fluid communication with the center valve through inlet ports, wherein it will begin to receive high pressure steam or compressed air from the center valve and release it into the working chamber behind it. However, as the piston continues to rotate, pressure continues to build in the working chamber in front of it, as the piston ahead of it will not yet have uncovered the exhaust port associated with the second flattened area (that is in an opposed location from the first flattened area). Once the exhaust port becomes uncovered, the advancing piston begins to move the steam or air from the previous power cycle through the exhaust port, giving a power boost to the piston ahead of it. Shortly thereafter, the piston ahead of it will come into fluid communication with the center valve via the opposing inlet port, and begin to release high pressure steam or compressed air into the working chamber ahead of it causing pressure to build in that working chamber until the piston ahead of it uncovers the next approaching exhaust port. When the present invention is used to power a motor vehicle, it will stop when the vehicle it powers is at rest, such as during a temporary stop at a traffic light. In addition, the present invention rotary engine has many advantages over a combustion engine, including but not limited to, the present invention is inexpensive to manufacture as there is not much tooling needed to make it; increasing horsepower simply involves increasing the width dimensions of the casing, rotor, and pistons; no crankshaft or connecting rods are needed when it is used to power a vehicle; it runs silently; compressed air adds no fuel weight/load to the vehicles it powers; it uses a small volume of air per cycle because the air is able to travel through its pistons; no wasteful energy is needed to cool it; no flammable fuel is used; it has breathable exhaust; no starter is required; and it instantly starts in cold weather. Also, air compressors associated with the present invention rotary engine can be electrically and/or mechanically driven. Applications are varied and many, including providing more reliable and economical power for motorized vehicles than is possible with a combustion engine. A small and compact present invention rotary engine has sufficient power to run a four passenger vehicle at 80-mph, with added horsepower easily achieved for larger vehicles by widening working chambers, piston, and rotor. 
   2. Description of the Related Art 
   Prior art rotary engines are known to comprise triangular-shaped rotors and vaned rotors, and many have their rotors mounted on eccentric shafts. Also, the rotor housings used in prior art rotary engines are known to comprise circular interior surfaces and two-lobed epitrochoidal interior surfaces. The rotary mechanism disclosed in U.S. Pat. No. 3,891,357 to Davis (1975) includes an interior surface having two arcuate lobes separated by two opposed flattened areas, as is found in the present invention. However, it also has differing structure to include an eccentric shaft/rotor relation, cooling nozzles 92 in ends walls 22 and 24 that provide a stream of cooling liquid to cool the rotor, exhaust ports 102 also through the end walls 22 and 24, and a gas inlet 100 through each of the opposed flattened areas. Furthermore, the Davis invention has structure configured to overcome oil sealing problems encountered with Wankel-type engines. The fixed center valve with opposing inlet ports, the peripheral exhaust ports, and the three-vane structure of the present invention are not disclosed as a part of the Davis invention. U.S. Pat. No. 4,047,856 to Hoffman (1977) discloses a rotary steam engine having a triangular-shaped hollow rotor, an eccentric shaft/rotor relation, radial grooves 72a-c and 73a-c in fluid communication with inlet ports 82 and 83 that help to conduct pressure fluid from the hollow rotor to the cavity lobes 20 and 21, and exhaust passages 80 and 81 through the housing wall. The present invention has no similar grooves and no eccentric shaft/rotor relation, and the Hoffman invention has no fixed center valve with opposing inlet ports, the peripheral exhaust ports, and the three-vane structure critical to the present invention. U.S. Pat. No. 4,115,045 to Wyman (1978) further discloses a rotary motor with spring-biased seals on the outer circular periphery of its rotor 12. Its rotor 12 has a hub 10, twenty-four radial spokes, and a circular rim 26. Multiple working chambers are defined by the seals, and a series of steam inlet and exhaust steam outlet pairs communicated with the chamber as the rotor is rotated by expansion of live steam against the radial spokes 24. Although both have vaned rotors, many differences exist between the Wyman motor and that of the present invention including the number of vanes and the number and positioning of inlet ports and exhaust ports. 
   Although important differences exist between it and the present invention, the rotary motor thought to be the closest to the present invention is the rotary motor disclosed in U.S. Pat. No. 1,953,378 to Vias (1934). The Vias invention comprises two adjacently positioned rotor housings having back-pressure eliminating ports that are able to move trapped fluid from one paired housing into the other according to need. Each housing also has one rotor with two vanes, and each vane having an expansion spring that constantly maintains it in engagement with the periphery of the housings working chamber (see page 1, lines 75-77). Thus, although the Vias motor has vanes with spring biasing similar to that used in the present invention, it does not teach the remainder of the present invention. Important differences in structure between the present invention and the Vias invention is that the present invention does not teach a paired housing structure with back-pressure eliminating ports, and the present invention rotor is centered within its casing, not eccentrically disposed therein. Also, the Vias motor has a cylindrical working chamber 17 with a circular periphery (see page 1, line 50 and FIGS. 3-4), while the present invention has an interior surface with two semi-circles separated by two opposed flattened areas, and in addition, its inlet ports and exhaust ports have different locations from that in the Vias motor. Also in the Vias invention, each rotor is formed with a centrally located circular exhaust chamber 23 (see page 1, lines 81-82). In the Vias invention, its intake ports 26/27 are formed through cylindrical members 16 and 16a (see FIGS. 2-4), its outlet ports 24/25 are formed through end head members 10 (see FIG. 2), and its exhaust chamber 23 is centrally located (see FIG. 4). In the present invention the opposite occurs, and a fixed valve having two opposed inlet ports is centrally located and two exhaust ports each located adjacent to a different one of the two opposed flattened area across which the free angled end of the pistons collectively move before they reach the adjacent flattened area. No other rotary engine is known to have the same structure, function in the same manner, or provide all of the advantages of the present invention. 
   BRIEF SUMMARY OF THE INVENTION 
   It is the primary object of this invention to provide an inexpensive and high efficiency rotary engine that uses compressed air or high pressure steam to produce power more advantageously than a combustion engine. It is also an object of this invention to provide a rotary engine that does not use flammable fuel. Further objects of this invention are to provide a rotary engine with only four moving parts, does not require a catalytic converter to meet environmental standards, and has breathable exhaust. It is also an object of this invention to provide a rotary engine that only uses a small volume of air per cycle, and has no wasteful energy lost in cooling it. Other objects of this invention are to provide a rotary engine that does not require a starter, instantly starts in cold weather, and does not run when the vehicle it powers has come to a temporary stop, such as at a stoplight. It is also an object of this invention to provide a rotary engine that runs silently. It is a further object of this invention to provide a rotary engine with an approximate 300-degree power stroke. 
   As described herein, properly manufactured and used, the present invention provides a rotary engine that can use compressed air or high pressure steam to produce power, and further produces three power strokes for each revolution of its rotor. Furthermore, the volume of air used for a single cycle of the present invention is less, because the air travels through the pistons/vanes. Its casing has a two-lobed working chamber, with the two lobes separated from one another by two opposed flattened areas. In addition, two exhaust ports are each adjacent to a different one of the flattened areas, three spring-biased and equally spaced-apart pistons depend from a rotor, and a center fixed valve with two inlet ports that provide high pressure steam or compressed air to each of the three pistons/vanes twice during one revolution of the rotor, resulting in an approximate 300-degree power stroke for each revolution of the rotor. The engine stops when the vehicle it powers is at rest, and the expansion spring in each piston/vane provides contact (a reactionary force) of the tip of the angled free end of each piston/vane with the interior surface of the two-lobed rotor casing upon start up. In addition, the present invention rotary engine is inexpensive to manufacture as there is not much tooling needed to make the rotary engine, it runs silently, it uses a small volume of air per cycle and has no wasteful energy lost in cooling it, no flammable fuel is used, its exhaust is breathable, no starter is required, it instantly starts in cold weather, and there are only four moving parts, its rotor and the three pistons/vanes attached to it via equally spaced-apart slots in the rotor. Multiple present inventions (using hydraulic fluids, compressed air or high pressure steam) can be placed side-by-side to increase torque. In addition, no crankshaft or connecting rods are needed to power a vehicle, and when compressed air is used, it is quiet during its operation. Furthermore, use of compressed air does not add any fuel weight to the vehicle it powers, adding to its fuel economy. The vanes/pistons of the present invention can be hardened stainless steel, although its rotor is preferably made from hardened bronze. The present invention is more reliable and economical than a combustion engine, the torque is high for a small engine, and it has a power stroke 3 times in 360 degrees. Thus, many advantages are provided by the present invention over combustion engine use. 
   While the description herein provides preferred embodiments of the present invention rotary engine, the examples provided should not be construed as limiting the scope of the present invention. For example, it is within the contemplation of the present invention to incorporate variations other than those shown and described herein, such as variations in the thickness dimension of the working chambers; the number of present invention motors that can be used in concert to provide power; the materials from which the casings, springs, and fixed valve are made; the number and size of fasteners used to secure the two halves of casing together; and the size of the piston&#39;s fuel delivery opening. Thus, the scope of the present invention rotary engine should be determined by the appended claims and their legal equivalents, rather than being limited to the examples given. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       FIG. 1  is a schematic view of a power stroke in the most preferred embodiment of the present invention rotary engine and showing three pistons under counterclockwise rotation within a space bounded by a casing having two peripheral exhaust ports therein, with three working chambers defined between the three rotating pistons, an expansion spring in each of three pistons, and a fixed center valve connected to two opposed inlet ports, and further with exhaust present being marked with interconnecting lines, while the compressed air or high pressure steam present is marked with substantially parallel rippled lines. 
       FIG. 2  is a sectional view of the most preferred embodiment of the present invention showing the narrow width of the space between opposed casing pieces in which the rotor and pistons move, fasteners connecting the casing pieces together, a mounting bracket attached to one of the casing pieces, a drive shaft secured through an opening in one casing, and the fixed valve secured through an opening in the opposed casing piece, and further with a steam/air delivery tube having threaded connection to the fixed valve, while the compressed air or high pressure steam present in the delivery tube, the two inlet ports, and one piston is marked with substantially parallel rippled lines. 
       FIG. 3  is a front view of one of the casing pieces in the most preferred embodiment of the present invention showing opposed flattened areas each adjacent to a different one of the two peripheral exhaust ports present, multiple perimeter fastener holes used for securing the two casing pieces together, two dowels also used for connecting the casing pieces together, broken lines identifying the central positioning of an extension behind the casing piece and outwardly-depending from it through which a drive shaft is inserted for connection to the rotor, broken lines also showing the bore through the drive shaft receiving extension, in addition to a solid circular line centrally in the casing piece that identifies a center opening/bore used to receive the fixed/non-rotating valve that in combination with inlet ports serially introduces air/steam into the three working chambers defined by the rotor, springs, and three pistons between the two joined casing pieces adjacent to the interior surfaces of both lobes, with a section line G-G also marked on one part of the casing piece. 
       FIG. 4A  is side view of the casing piece shown in  FIG. 3 , with the drive shaft receiving extension, its central bore, the center opening/bore used to receive the fixed/non-rotating valve, two fasteners holes, and the location of one of the flattened areas all being illustrated. 
       FIG. 4B  is side view of the casing piece shown in  FIG. 3 , with a thickened central area having a central bore configured and sized to receive the fixed valve used to introduce air/steam into the working chambers, two fasteners holes, and the location of one of the flattened areas all being illustrated. 
       FIG. 5  is sectional view along the G-G line in  FIG. 3 , showing the solid construction of the casing piece shown in  FIG. 3 . 
       FIG. 6  is a front view of a rotor usable as a part of the most preferred embodiment of the present invention and showing three equally spaced-apart slots each used to receive a different one of the pistons, broken lines identifying a thickened central area behind the rotor and extending outwardly from it to engage from the drive shaft, or depend from it, and solid lines indicating the receiving bore/hole for the fixed valve. 
       FIG. 7  is a side view of the rotor shown in  FIG. 5  showing the thickened central area with a central bore configured and sized to receive the drive shaft, with broken lines indicating the receiving bore/hole for the fixed valve. 
       FIG. 8  is a front view of a fixed valve usable as a part of the most preferred embodiment of the present invention, with a central hole used for fluid communication with a source of high pressure steam or compressed air, two opposed inlet ports in fluid communication with the central hole that deliver steam/air to rotating pistons, and an angle marked by the letter “a” that indicates the orientation needed for the inlet ports relative to the flattened areas of the casing for optimal working efficiency of the rotary engine. 
       FIG. 9  is a side view of the fixed center valve shown in  FIG. 8  with the central hole used for fluid communication with a source of high pressure steam or compressed air shown intersecting with inlet ports  10  and  10 ′. 
       FIG. 10  is a front view of the fixed center valve shown in  FIG. 8  and its central hole used for fluid communication with a source of high pressure steam or compressed air. 
       FIG. 11  is a front view of a piston usable as a part of the most preferred embodiment of the present invention, which is inserted into one of the slots in the rotor, and showing a chamfer at the top end of the piston, the angled tip at the bottom end of the piston that engages the interior wall of the casing as the piston rotates, the receiving chamber for an expansion spring, a steam/air delivery opening near the angled tip, and the connecting tube providing fluid communication between the receiving chamber and the delivery opening. 
       FIG. 12  is a side view of the piston in the most preferred embodiment of the present invention rotated 90-degrees from the piston shown in  FIG. 11 , and showing the angled tip at the bottom end of the piston as it engages the interior wall of the casing, the angled clearance between the slanted bottom surface of the piston and the interior wall of the casing, the receiving chamber for an expansion spring, a steam/air delivery opening near the angled tip, and the connecting tube providing fluid communication between the receiving chamber and the delivery opening. 
       FIG. 13  is an end view of the piston shown in  FIG. 11  showing the receiving chamber for an expansion spring, a steam/air delivery opening near the angled tip, and the connecting tube providing fluid communication between the receiving chamber and the delivery opening. 
   

   COMPONENT LIST IDENTIFYING REFERENCE NUMBERS USED IN THE DRAWINGS 
   
       
         2 —rotary engine 
         4 —piston (also marked as D, E, and F in  FIG. 1  for discussion purposes) 
         6  and  6 ′—the two pieces that together form the casing within which rotor  32  and pistons  4  rotate (preferably made from two pieces of hardened bronze that are joined together by multiple fasteners  26 ) 
         8 —fixed center valve used to deliver compressed air or high pressure steam  14  to inlet ports  10  and  10 ′ (non-rotating and connected to tubing  58 ) 
         10  and  10 ′—central inlet ports in fluid communication with fixed center valve  8   
         12  and  12 ′—peripheral exhaust ports through the casing made from casing pieces  6  and  6 ′ (positioned adjacent to one of the flattened areas within the casing so that pistons pass over the exhaust port before moving across the associated flattened area) 
         14 —high pressure steam or compressed air 
         16 —exhaust 
         18 —expansion spring 
         20 —delivery opening in piston  4  below connecting tube  42  (the openings  20  in all pistons  4  connected to the same rotor  32  will be oriented in like direction and location relative to casing pieces  6  and  6 ′ and rotor  32 ) 
         22  and  22 ′—opposed flattened areas in casing pieces  6  and  6 ′ (with one adjacent to each exhaust port  12  or  12 ) 
         24 —angled clearance between the slanted bottom surface of each piston  4  and the inside wall of the adjacent casing piece  6  or  6 ′ 
         26 —fastener for use in connecting casing pieces  6  and  6 ′ together so as to provide a secure and leak proof connection between them 
         28 —holes in casing pieces  6  and  6 ′ for fasteners 
         30 —receiving chamber in piston  4  for spring  18   
         32 —rotor having slots  54  each used to receive one piston  4   
         34 —mounting bracket (example of one type of mounting bracket that can be used to secure casing pieces  6  and  6 ′ in a fixed location during use) 
         36 —dowel used to secure casing pieces  6  and  6 ′ together 
         38 —drive shaft connected to rotor  32   
         40 —center bore or hole through casing pieces  6  and  6 ′ that is used for receiving fixed valve  8   
         42 —connecting tube in piston  4  providing fluid communication between receiving chamber  30  and delivery opening  20   
         44 —angled tip on the free end of piston  4  that engages the interior surfaces of casing pieces  6  and  6 ′ 
         46 —45-degree chamfer in end of piston  4  adjacent to fixed valve  8  (reduces interference with spring  18  on start-up) 
         48 —central hole in fixed valve  8  through which high pressure steam or compressed air  14  is delivered to inlet ports  10  and  10 ′ (also preferably has a threaded opening  56  configured for secure connection to a steam/air delivery tubing  58 ) 
         50 —extension outwardly-depending from casing  6  with a through bore dimensioned to receive drive shaft  38   
         52 —bore through casing  6  dimensioned for receiving drive shaft  38   
         54 —slot in rotor  32  used for receiving a piston  4  (marked as R, S, and T in  FIG. 6  for discussion purposes) 
         56 —threaded opening leading to central hole  48  in fixed valve  8   
         58 —tubing connected to the central hole  48  in fixed valve  8  via threaded opening  56 , and which is used to deliver high pressure steam or compressed air  14  to inlet ports  10  and  10 ′ (which then travels through rotating pistons  4  into working chambers A, B, and C) 
         60 —fastener used to maintain valve  8  within the center bore  40  in casing  6 ′ 
         62 —thickened central area depending outwardly from rotor  32  that engages or depends from drive shaft  38  (it also has a bore/opening  40  that houses the interior most portion of fixed valve  8 ) 
         64 —hole/bore extending between slot  54  and the center hole  40  in rotor  32   
       A, B, and C—working chambers in  FIG. 1  defined by pistons  4 , rotor  32 , and casing pieces  6  and  6 ′ (marked as A, B, and C for discussion purposes) 
       a—angle that is preferably 28-degrees and related to the optimal positioning of inlet ports  10  and  10 ′ relative to exhaust ports  12  and  12 ′ 
     
  
   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention rotary engine  2  can use compressed air or high pressure steam  14  to produce power more advantageously than a combustion engine. Each revolution of the present invention rotor  32  and pistons  4  produces three power strokes. Furthermore, the volume of air  14  used for a single cycle of the present invention rotary engine  2  is less, since the compressed air  14  travels through its pistons/vanes  4  (also marked as D, E, and F in  FIG. 1  to facilitate the description herein). Its casing is made from two casing pieces  6  and  6 ′ that are joined together via fasteners  26 , and it also has two exhaust ports  12  and  12 ′ each adjacent to one of the flattened areas  22  and  22 ′ that are a part of the casings interior surface against which the angled tips  44  of the pistons  4  make contact. Flattened areas  22  and  22 ′ are in opposed positions from one another; with three spring-biased and equally spaced-apart pistons  4  inserted into slots  54  in a rotor  32  positioned for rotation within the casing made from casing pieces  6  and  6 ′. The present invention rotary engine  2  also has a center valve  8  in fluid communication with two opposed inlet ports  10  and  10 ′ that provide high pressure steam or compressed air  14  (distinguished visually in  FIG. 1  by substantially parallel rippled lines) to the hollow pistons/vanes  4  wherein each revolution of rotor  32  produces three power strokes. Also, rotary engine  2  stops when the vehicle (not shown) that it powers is at rest, and the springs  18  located within the pistons/vanes  4  provide contact between them and the casings interior surface (a reactionary force) upon start up. In addition, rotary engine  2  is inexpensive to manufacture as there is not much tooling needed to make rotary engine  2 . Also, rotary engine  2  runs silently, it uses a small volume of air  14  per cycle and has no wasteful energy lost in cooling it, no flammable fuel is used and its exhaust  16  is breathable, no starter is required and rotary engine  2  instantly starts in cold weather, and there are only four moving parts, its rotor  332  and the three pistons/vanes  4  attached to it.  FIG. 1  shows the relative positioning of high pressure steam or compressed air  14  and exhaust  16  during a power stroke in the three identified working chambers (marked as A, B, and C for descriptive purposes) of the most preferred embodiment of the present invention rotary engine  2 , as the rotor  32  and pistons  4  rotate in a counterclockwise direction. In contrast,  FIG. 2  shows a sectional view of the rotary engine  2  in  FIG. 1  and the narrow width of the space created between casing pieces  6  and  6 ′ used for the rotation of rotor  32  and the pistons  4  inserted into its slots  54 . In addition,  FIG. 3  shows casing  6  and the preferred positioning of exhaust valves  12  and  12 ′, flattened areas  22  and  22 ′, and fastener holes  28 .  FIGS. 4A ,  4 B, and  5  also show side and sectional views of casing pieces  6  and  6 ′. Furthermore,  FIGS. 6 and 7  show the preferred structure for rotor  32  and pistons  4 , while  FIGS. 8-10  show preferred structure for fixed center valve  8  and the opposed inlet ports  10  and  10 ′ that are in fluid communication between fixed center valve  8  and the rotating pistons  4 . Finally,  FIGS. 11-13  show preferred structure for pistons/vanes  4  (hereinafter ‘pistons  4 ’ without any intention of limitation), the angled clearance  24  between the end surface of each piston  4  and the interior surface of casing pieces  6  and  6 ′, and the opening  20  in each piston  4  through which high pressure steam or compressed air  14  is introduced into the working chambers D, E, and F defined by rotor  32 , casing pieces  6  and  6 ′, and pistons  4 . Although the components shown in  FIGS. 1-13  represent the most preferred embodiment of the present invention, some variation thereof is contemplated and considered to also be within the scope of the present invention. Therefore, one should consult the appended claims for a determination of the full scope of the present invention rotary engine  2 . 
     FIG. 1  is a schematic view of a power stroke in the most preferred embodiment of the rotary engine  2 , which shows a rotor  32  and three pistons  4  (further individually marked by the letters D, E, and F for descriptive purposes) positioned for rotation relative to the interior space made from the joining of two similar casing pieces  6  and  6 ′ (casing piece  6  is shown in  FIG. 1 ) that are secured to one another with multiple fasteners  26  (see  FIG. 2 ) each inserted through a different fastener hole  28  (see  FIG. 3 ).  FIG. 1  also shows pistons  4 , rotor  32 , and casing piece  6  further defining three working chambers A, B, and C that are adjacent to the interior surface of casing piece  6 , and further with piston D located so that it is in fluid communication with a fixed center valve  8  via inlet port  10 , wherein high pressure steam or compressed air  14  (marked by substantially parallel rippled lines) is able to flow through piston D and into working chamber C. Neither piston E or piston F are shown in  FIG. 1  to be in fluid communication with the opposed inlet valve  10 ′, although due to the counterclockwise rotation for pistons  4  indicated by the large arrow in  FIG. 1 , fluid communication between piston E and inlet valve  10 ′ is imminent. In addition,  FIG. 1  shows high pressure steam or compressed air  14  (distinguished visually by substantially parallel rippled lines in chambers B and C) before its compression by the next advancing piston  4  (E or F), which is imminent in working chamber B by approaching piston E. In contrast in  FIG. 1 , exhaust  16  is visually distinguished by the use of crossed lines and spaced-apart arrows that lead to and through exhaust ports  12  and  12 ′, as shown in working chambers A and C, with pistons D and F respectively moving exhaust  16  toward exhaust ports  12  and  12 ′. Furthermore, as shown in  FIG. 1 , piston D will continue to deliver high pressure steam or compressed air  14  into working chamber C via opening  20  near its angled surface on its free end, until it reaches a comparable position to that shown for piston F in  FIG. 1  relative to the opposing inlet port  10 , where fluid communication with the fixed center valve  8  has ceased.  FIG. 1  also shows the angled/slanted free ends of pistons D, E, and F that provide angled clearance  24  between each piston  4  and the interior surface of casing pieces  6  and  6 ′. In addition,  FIG. 1  shows each piston D, E, and F having an expansion spring  18  that biases the angled tip  44  of piston D, E, or F against the interior surface of casing pieces  6  and  6 ′ to create a reactionary force upon start up of rotor  32 .  FIG. 1  further shows the flattened areas  22  and  22 ′ over which the pistons D, E, and F pass after closing the working chamber (A, B, or C) in front of it to fluid communication with an exhaust port  12  or  12 ′. The drive shaft  38  (shown in  FIG. 2 ) and which connected to (or depends from) rotor  32 , is not illustrated in  FIG. 1  as it would be behind rotor  32 . Applications for the present invention rotary engine  2  are varied and many, including providing more reliable and economical power for motorized vehicles than is possible with a combustion engine. Examples of relative dimensions used to construct a working prototype of the present invention rotary engine  2 , which would be able to power a four passenger car up to 80 mph, are presented in a subsequent paragraph herein below. The width dimensions of the rotor  32 , pistons  4 , and casing pieces  6  and  6 ′ can be varied, and if widened will increase the horsepower of rotary engine  2 . 
     FIG. 2  is a sectional view of the most preferred embodiment of the present invention rotary engine  2 .  FIG. 2  shows fasteners  26  and  26 ′ securing casing piece  6  to casing piece  6 ′ (although in  FIG. 3  one can see additional fastener holes  28  that are used to receive additional fasteners  26  that also help to secure casing piece  6  to casing piece  6 ′).  FIG. 2  further shows a mounting bracket  34  connected to fastener  26 ′, as an example of one type of mounting that is contemplated for rotary engine  2 . However, it should be understood that it is not intended for the type of mounting (bracket or otherwise) used for rotary engine  2  to be limited to that shown in  FIG. 2 . In addition,  FIG. 2  shows a drive shaft  38  extending through casing piece  6 , and the fixed center valve  8  extending through casing piece  6 ′.  FIG. 2  also shows peripheral exhaust ports  12  and  12 ′ at the top and bottom of the illustration, with flattened area  22 ′ marked between exhaust port  12 ′ and rotor  32 . When viewing  FIG. 1 , one can see the angled top of piston E against flattened area  22  and not extending beyond the perimeter edge of rotor  32 , while the expansion springs  18  in pistons D and F cause them to become extended beyond the perimeter edge of rotor  32  so that their angled tips  44  can reach the arcuate interior surfaces of the two opposed lobes formed between flattened areas  22  and  22 ′.  FIG. 2  shows no visible clearance between rotor  32  or piston  4  and casing pieces  6  and  6 ′, with the mounting of rotor  32  between casing pieces  6  and  6 ′ requiring a close fit therebetween so that high pressure steam or compressed air can become further compressed to cause a power stroke in working chambers A, B, and C by the advancement of rotating pistons  4 , however, the clearance between rotor  32  or piston  4  and casing pieces  6  and  6 ′ must be sufficient to allow rotational movement of pistons  4  and rotor  32  between casing pieces  6  and  6 ). In addition,  FIG. 2  shows the delivery opening  20  near the angled tip  44  of piston  4 , with substantially parallel rippled lines and a longitudinal arrow pointing toward delivery opening  20  representing high pressure steam or compressed air  14  flowing through piston  4  for delivery via opening  20  into a working chamber (A, B, or C as shown in  FIG. 1 ). The spring  14  shown in  FIG. 2  is housed within receiving chamber  30  in piston  4 , with connecting tube  42  below receiving chamber  30  providing fluid communication between receiving chamber  30  and delivery opening  20  that allows high pressure steam or compressed air  14  to pass through piston  4  and enter a working chamber as long as the proximal end of piston  4  (A, B, or C as shown in  FIG. 1 ), as long as the proximal end of piston  4  is in fluid communication with either of the two opposed inlet ports  10  or  10 ′. Thus,  FIG. 2  shows a piston  4  in a position below fixed valve  8  that is receiving high pressure steam or compressed air  14  from inlet port  10 , while only the rotor  32  is shown in a position above fixed valve  8  with no flow of high pressure steam or compressed air  14  beyond the distal end of inlet port  10 ′. Furthermore,  FIG. 2  identifies the extension  50  outwardly-depending from casing  6  with a through bore  52  dimensioned to receive drive shaft  38 , and the center bore  40  in casing piece  6  that is used for receiving the interior end of fixed valve  8 . Although not identified in  FIG. 2 , a center bore  40  is also formed in casing piece  6 ′ for use in receiving the remainder of fixed valve  8 .  FIG. 2  further shows a fastener  60  that helps to maintain fixed valve  8  in its desired position of use and prevents its rotation, a central hole  48  in fixed valve  8 , and tubing  58  connected to central hole  48  via a threaded opening  56  that provides fluid tight connection therebetween. Although not shown in  FIG. 2 , tubing  58  is connected to a source of high pressure steam or compressed air  14  that is shown moving through tubing  58 , into the central hole  48  in fixed valve  8  and then into inlet ports  10  and  10 ′, wherein when a piston  4  during its rotation with rotor  32  becomes aligned with inlet port  10  or  10 ′, the high pressure steam or compressed air  14  traveling into inlet port  10  or  10 ′ will be caused to move into piston  4  and thereafter be delivered through opening  20  into the working chamber (A, B, or C as shown in  FIG. 1 ) that is immediately behind piston  4  as it advances toward the next approaching exhaust port  12  or  12 ′. 
     FIGS. 3 ,  4 A,  4 B, and  5  show casing pieces  6  and  6 ′ as they would appear in the most preferred embodiment of the present invention rotary engine  2 . Although not critical, in the most preferred embodiment of the present invention, it is contemplated for casing pieces  6  and  6 ′ to be made from stainless steel.  FIG. 3  shows casing piece  6  having opposed flattened areas  22  and  22 ′ respectively adjacent to exhaust ports  12  and  12 ′ in a position where rotating pistons  4  pass over exhaust ports  12  and  12 ′ prior to passing over the adjacent flattened areas  22  or  22 ′.  FIG. 3  also shows a solid circular line representing the center opening  40  through casing  6  that receives the innermost portion of fixed valve  8 , and broken lines representing the extension  50  outwardly-depending from casing  6  with its through bore  52  dimensioned to receive drive shaft  38  that allows connection of the drive shaft  38  to rotor  32 .  FIG. 3  also shows multiple fastener holes  26  around its perimeter that are used with fasteners  26  to securely connect casing piece  6  to casing piece  6 ′.  FIG. 3  also shows one position adjacent to each flattened area  22  and  22 ′ where a dowel  36  is inserted for enhanced alignment and fluid tight connection of casing pieces  6  and  6 ′ to one another. In addition,  FIG. 3  shows the line G-G that defines the location where the sectional view of casing  6  shown in  FIG. 5  is taken, which reveals a solid construction for casing piece  6  (which is also anticipated and preferred for the casing piece  6 ′ used in the most preferred embodiment of the present invention rotary engine  2 . In contrast,  FIGS. 4A and 4B  are side views respectively of casing pieces  6  and  6 ′, which are substantially similar in configuration.  FIG. 4A  shows multiple fastener holes  28  through casing piece  6 , a central location for fixed valve  8 , the drive shaft  38  receiving extension  50  and its central bore  52 , and the location of flattened area  22 .  FIG. 4B  shows the structure of casing piece  6 ′, with a thickened central area (unnumbered) having a central bore  40  configured and sized to receive the fixed valve  8  used to introduce air/steam  14  into the working chambers (A, B, and C shown in  FIG. 1 ), two fasteners holes  28 , and the location of flattened area  22 ′. The thickness of casing pieces  6  and  6 ′ is not limited to that shown in  FIGS. 3 ,  4 A,  4 B, and  5 , and could vary according to the horsepower needed from rotary engine  2 . 
     FIGS. 6 and 7  show the rotor  32  in the most preferred embodiment of the present invention rotary engine  2 , with the three slots  54  that each receive a piston  4 . Slots  54  are additionally marked with the designations R, S, and T in  FIGS. 6 and 7  for descriptive purposes.  FIG. 6  is a front view of a rotor  32  that is usable as a part of the most preferred embodiment rotary engine  2 , which shows three equally spaced-apart slots  54  each used to receive a different one of the pistons  4 . Broken lines through two of the slots  54  indicate the center line for that slot  54 , and a double-headed arrow is provided to show a 120-degree separation between adjacent slots  54 . Each slot  54  is shown to be open-ended, so that the expansion spring  18  within each piston  4  can move it beyond the perimeter surface of rotor  32  as needed during the transition from a flattened area  22  or  22 ′ to one of the acruate lobes positioned between flattened areas  22  and  22 ′ so as to maintain bias of the angled tip  44  of each piston  4  against the interior surface of casing pieces  6  and  6 ′. Circular broken line  62  represents thickened central area depending outwardly from rotor  32  that engages or depends from drive shaft  38 , with the solid circular concentric line within broken line  62  representing the bore/opening  40  that receives the interior most portion of fixed valve  8  (see  FIG. 7 ). The designations of R, S, and T are helpful in viewing  FIG. 7 , which is a side view of the rotor shown in  FIG. 6 . The thickened central area  62  is shown with broken lines that indicate the central bore  40  configured and sized to receive the interior most portion of fixed valve  8 . Thickened central area  62  may be connected to a drive shaft  38 , or otherwise depend from it. The positioning of inlet ports  10  and  10 ′ are also shown in  FIG. 7 , in addition to the location of the open-ended three slots  54 , each of which is indicated by its respective letter designation R, S, or T. The slot  54  designated by the letter T is marked in broken lines, as it is pointed away from a viewer and would otherwise be hidden in  FIG. 7 . 
     FIGS. 8-10  show more structural detail about the fixed center valve  8  in the most preferred embodiment of the present invention rotary engine  2 .  FIG. 8  is a front view of a fixed valve  8  that is usable as a part of rotary engine  2 , with a central hole  48  used for fluid communication with a source (not shown) of high pressure steam or compressed air  14 . Two opposed inlet ports  10  and  10 ′ are in fluid communication with central hole  48  and are used to deliver steam/air  14  to rotating pistons  4 . Inlet ports  10  and  10 ′ both become widened on their distal ends, so that a sufficient amount of high pressure steam or compressed air  14  can pass through each piston  4  to achieve optimal power strokes within working chambers A, B, and C (see  FIG. 1 ).  FIG. 8  also shows an angle marked by the letter “a” that indicates the orientation needed for the inlet ports  10  and  10 ′ relative to the flattened areas  12  and  12 ′ of the casing pieces  6  and  6 ′ for optimal working efficiency of the rotary engine. In the inventor&#39;s prototype, angle “a” was approximately 28-degrees, and placed the center line extending through inlet ports  10  and  10 ′ approximately 28-degrees below a center line (not shown in  FIG. 1 ) that would extend through casing  6  between flattened areas  22  and  22 ′.  FIG. 9  is a side view of the fixed center valve  8  with its central hole  48  used for fluid communication with a source of high pressure steam or compressed air  14  via a tubing  58  that preferably would have a threaded connection  56  (see  FIG. 2 ) to central hole  48  to provide a fluid tight connection therebetween. Central hole  48  is shown in  FIG. 9  in substantially perpendicular orientation to and intersecting with inlet ports  10  and  10 ′.  FIG. 10  is a front view of the fixed center valve  8  shown in  FIGS. 8 and 9  and the positioning of its central hole  48  used for fluid communication with a source of high pressure steam or compressed air  14 , which passes through fixed valve  8  and enters rotating pistons  4  as they become periodically aligned with inlet ports  10  and  10 ′. The size of central hole  48  relative to the diameter dimension of fixed valve  8  shown in  FIG. 10  should not be considered as limited to that shown in  FIGS. 8-10 . Although not critical, in the most preferred embodiment of the present invention rotary engine  2 , it is contemplated for fixed center valve  8  to be made from stainless steel. 
     FIGS. 11-13  show further structural detail for pistons  4  used in the most preferred embodiment of the present invention rotary engine  2 .  FIG. 11  is a front view of a piston  4  usable as a part of the most preferred embodiment of the present invention, which is inserted into one of the slots  54  in rotor  32 .  FIG. 11  shows a chamfer at the top end of piston  4  that upon start-up of rotary engine  2  reduces interference with the expansion spring  18  housed within piston  4 .  FIG. 11  also shows the angled tip  44  at the bottom end of each piston  4  that engages the interior wall of casing pieces  6  and  6 ′ as the piston  4  rotates with rotor  32 , with the broken line immediately above the line representing angled tip  44  indicating the rear portion of the slanted/inclined bottom surface of the piston  4  that reduces friction as piston  4  and rotor  32  rotate relative to casing pieces  6  and  6 ′.  FIG. 11  also shows the receiving chamber  30  configured for housing expansion spring  18 , a steam/air delivery opening  20  near the angled tip  44 , and the connecting tube  42  providing fluid communication for high pressure steam or compressed air  14  between receiving chamber  30  and delivery opening  20 .  FIG. 12  is a side view of the piston  4  in the most preferred embodiment of the present invention rotated 90-degrees from the piston  4  shown in  FIG. 11 .  FIG. 12  also shows the relative positioning of an adjacent portion of casing piece  6 . The angled tip  44  at the bottom end of the piston  4  shown in  FIG. 12  is in contact with the interior wall of casing piece  6 , and the inclined/slanted bottom surface of piston  4  provides the angled clearance  24  from casing  6  that is identified by the number  24 . In addition,  FIG. 12  shows the receiving chamber  30  for housing an expansion spring  18 , a steam/air delivery opening  20  near the angled tip  44 , and the connecting tube  42  providing fluid communication between receiving chamber  30  and delivery opening  20 .  FIG. 13  is an end view of the piston shown in  FIGS. 11 and 12 , which shows a substantially cylindrical receiving chamber  30  for expansion spring  18 , a steam/air delivery opening  20  extending away from receiving chamber  30 , and the connecting tube  42  providing fluid communication between receiving chamber  30  and delivery opening  20 . Although not critical, in the most preferred embodiment of the present invention, it is contemplated for expansion springs  18  housed within receiving chambers  30  to be made from stainless steel. 
   Although not limited thereto, examples of size dimensions possible for use in the present invention include the following. For a drive shaft  38  having a diameter dimension of approximately one inch, the flattened areas  22  and  22 ′ on the inside of working chambers A, B, and C are expected to be approximately one inch in length dimension, with corresponding flattened areas on the outside surfaces (not assigned a reference number) of casings  6  and  6 ′ having an approximate one-and-one-half inch length dimension. Furthermore, the anticipated diameter dimension of exhaust ports  12  and  12 ′ is approximately one-fourth of an inch. Also, the width and thickness dimensions of the perimeter walls in casings  6  and  6 ′ through which fasteners holes  28  having a diameter dimension of approximately nine-thirty-seconds of an inch are formed, respectively are approximately three-fourths of an inch and approximately one-half inch. Additionally, the length and width dimensions of each piston  4  respectively are approximately one-and-one-half inches and approximately one-half inch, while the length and diameter dimensions of the cylindrical receiving chamber  30  within each piston  4  used for containment of an expansion spring  18  respectively are approximately one-and-one-sixteenth of an inch and approximately three-eighths of an inch. Furthermore, the diameter dimension of the opening  20  adjacent to the angled bottom end of each piston  4  is approximately three-sixteenths of an inch, with its center approximately five-thirty seconds of an inch above angled tip  44 . Furthermore, the corresponding maximum contact area of the angled tip  44  with the interior surface of casing pieces  6  and  6 ′ is approximately 0.062 inches. In addition, (although not limited thereto) it is contemplated in the most preferred embodiment of the present invention rotary engine  2  for the fixed center valve  8  to have a length dimension of approximately one-and-one-half inch, a diameter dimension slightly less than one inch, inlet ports  10  centered at approximately three-fourths of an inch within fixed center valve  8 , and the diameter dimension of the center hole  48  used for connection of tubing  58  (that is in fluid communication with a source of high pressure steam or compressed air  14 ) having diameter and length dimensions of approximately five-sixteenths of an inch and approximately one-and-one-eight inches. Furthermore, the corresponding height and width dimensions for widened portions of inlet ports  10  which respectively are approximately three-sixteenths of an inch and approximately five-sixteenths of an inch. Additionally, the corresponding diameter dimension of rotor  32  would be slightly larger than five inches, and the diameter dimension of each hole/bore  64  extending between a slot  54  and the center hole  40  in rotor  32  is approximately three-sixteenths of an inch Since it is also contemplated for the present invention to incorporate variations other than those shown and described herein, the scope of the present invention should be determined by the appended claims and their legal equivalents, rather than being limited to the examples given. A small and compact present invention rotary engine  2 , such as disclosed hereinabove has sufficient power to run a four passenger vehicle at 80-mph, with added horsepower easily achieved for larger vehicles by increasing the width dimensions of working chambers (A, B, and C), pistons  4 , each casing piece  6  and  6 ′, and rotor  32 . Although not shown in the accompanying illustrations, oil bearing access would be provided between drive shaft  38  and extension  50 , as well as between drive shaft  38  and fixed valve  8 .