Patent Publication Number: US-9903238-B2

Title: Rotary valve assembly having rotatable throttle and intake assemblies

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 14/619,522 filed Feb. 11, 2015, titled “Practical Steam Engine,” which application is incorporated by reference herein in its entirety. 
    
    
     BACKGROUND 
     Many forms of power generation in thermal-fluid systems use engines for converting expansive pressure into mechanical and/or electrical power. Various engines have specific advantages and disadvantages when compared. Turbine engines offer advantages of high speed operation and high power density. However, turbines often suffer from an inability to efficiently operate in varying flow conditions. Non-turbine engines (e.g., traditional steam engines) have advantages of being very capable of operating efficiently in varying flow conditions but typically operate at very slow speeds resulting in relatively low power outputs. A desirable combination is a high speed engine design that would allow the efficient operation at varying flow conditions while producing high power outputs. One of the primary reasons for past failures to cure this deficiency is the inability to get the working fluid in and out of the engine fast enough and efficiently enough to allow this high speed operation. One major limitation of the speed of the exchange process is the valvetrain. 
     Applicant has identified a number of additional deficiencies and problems associated with conventional valvetrains and other associated systems and methods. Through applied effort, ingenuity, and innovation, many of these identified problems have been solved by developing solutions that are included in embodiments of the present invention, many examples of which are described in detail herein. 
     BRIEF SUMMARY OF THE INVENTION 
     Generally, some embodiments provided herein include rotary valve assemblies, valvetrains, engines, and associated methods. A rotary valve assembly may include a valve housing defining a cylindrical bore, an inlet, and an outlet. The rotary valve assembly may include an intake assembly configured to be at least partially received within the cylindrical bore of the valve housing. The intake assembly may include an intake body defining a cylindrical bore and having at least one intake inlet port and at least one intake chamber port. The rotary valve assembly may further include a throttle assembly configured to be at least partially received within the cylindrical bore of the intake assembly. The throttle assembly may include a throttle body defining at least one throttle inlet port and at least one throttle chamber port. The throttle assembly and the intake assembly may be concentric with respect to a longitudinal axis. In some embodiments, the throttle assembly and the intake assembly may be configured to rotate independently of one another about the longitudinal axis. The at least one intake chamber port and the at least one throttle chamber port may at least partially overlap in a longitudinal direction. The at least one intake inlet port and the at least one throttle inlet port may at least partially overlap in the longitudinal direction. In some embodiments, during operation of the rotary valve assembly, the valve housing may be configured to permit fluid to enter the cylindrical bore of the valve housing via the inlet. The intake assembly may be configured to rotate to permit the fluid to flow through the at least one intake inlet port and the at least one throttle inlet port into the throttle body. The intake assembly may be configured to permit the fluid to flow to the outlet from the throttle body through the at least one throttle chamber port and the at least one intake chamber port. 
     In some embodiments, the at least one intake chamber port may include at least two intake chamber ports spaced symmetrically about a circumference of the intake body. The at least one throttle chamber port may include one throttle chamber port. 
     The at least one intake chamber port may be spaced from the at least one intake inlet port in the longitudinal direction. In some embodiments, the at least one intake chamber ports may include a greater number of ports than the at least one throttle chamber port. 
     In some embodiments, the rotary valve assembly may include at least one throttle bearing between the intake body and the throttle body, and may include at least one seal between the at least one throttle bearing and at least one of the at least one intake inlet port, the at least one throttle inlet port, the at least one intake chamber port, or the at least one throttle chamber port. The rotary valve assembly may further include vents disposed between the at least one throttle bearing and the at least one seal. The vents may be to apply a vacuum between the at least one throttle bearing and the at least one seal. 
     Some embodiments of the rotary valve assembly may include a first pair of bearings between the bore of the valve housing and the intake assembly at a first end of the intake assembly, and a second pair of bearings between the bore of the valve housing and the intake assembly at a second end of the intake assembly. In some embodiments, the rotary valve assembly may include at least one seal between the at least one of the first pair of bearings or the second pair of bearings and at least one of the at least one intake inlet port, the at least one throttle inlet port, the at least one intake chamber port, or the at least one throttle chamber port. The rotary valve assembly may further include vents disposed between the at least one of the first pair of bearings or the second pair of bearings and the at least one seal. The vents may be configured to apply a vacuum between the at least one of the first pair of bearings or the second pair of bearings and the at least one seal. 
     In some embodiments, the rotary bushing disposed between the valve housing and a rear end of the throttle assembly. 
     In some other embodiments, an engine may be provided that includes a rotary valve assembly. The rotary valve assembly may include a valve housing defining a cylindrical bore, an inlet, and an outlet. The rotary valve assembly may further include an intake assembly configured to be at least partially received within the cylindrical bore of the valve housing. The intake assembly may include an intake body defining a cylindrical bore and having at least one intake inlet port and at least one intake chamber port. The rotary valve assembly may include a throttle assembly configured to be at least partially received within the cylindrical bore of the intake assembly. The throttle assembly may include a throttle body defining at least one throttle inlet port and at least one throttle chamber port. The throttle assembly and the intake assembly may be concentric with respect to a longitudinal axis. The throttle assembly and the intake assembly may be configured to rotate independently of one another about the longitudinal axis. The at least one intake chamber port and the at least one throttle chamber port may at least partially overlap in a longitudinal direction. The at least one intake inlet port and the at least one throttle inlet port may at least partially overlap in the longitudinal direction. The engine may further include a chamber housing comprising a chamber therein. The valve housing may be rigidly attached to the chamber housing. The rotary valve assembly may be in fluid communication with the chamber via the valve housing chamber port. In some embodiments, during operation of the engine, the valve housing may be configured to permit fluid to enter the cylindrical bore of the valve housing via the inlet. The intake assembly may be configured to rotate to permit the fluid to flow through the at least one intake inlet port and the at least one throttle inlet port into the throttle body. The intake assembly may be configured to permit the fluid to flow to the outlet and into the chamber from the throttle body through the at least one throttle chamber port and the at least one intake chamber port. 
     In some embodiments, the engine may consists of at least one of a uniflow engine, a semi-uniflow engine, or a counter flow engine. 
     Some embodiments of the engine may further include at least one throttle bearing between the intake body and the throttle body. The engine may include at least one seal between the at least one throttle bearing and at least one of the at least one intake inlet port, the at least one throttle inlet port, the at least one intake chamber port, or the at least one throttle chamber port. The engine may further include vents disposed between the at least one throttle bearing and the at least one seal. The vents may be configured to apply a vacuum between the at least one throttle bearing and the at least one seal. 
     In some embodiments, the engine may include a first pair of bearings between the bore of the valve housing and the intake assembly at a first end of the intake assembly, and a second pair of bearings between the bore of the valve housing and the intake assembly at a second end of the intake assembly. The rotary valve assembly may further include at least one seal between the at least one of the first pair of bearings or the second pair of bearings and at least one of the at least one intake inlet port, the at least one throttle inlet port, the at least one intake chamber port, or the at least one throttle chamber port. In some embodiments, the rotary valve assembly may further include vents disposed between the at least one of the first pair of bearings or the second pair of bearings and the at least one seal. The vents may be configured to apply a vacuum between the at least one of the first pair of bearings or the second pair of bearings and the at least one seal. 
     The valve housing may further include an exhaust cylindrical bore. The rotary valve assembly may further include an exhaust assembly configured to be at least partially received within the exhaust cylindrical bore of the valve housing. The exhaust assembly may include an exhaust body defining a cylindrical bore and may have at least one exhaust outlet port and at least one exhaust chamber port. 
     In some embodiments, the valve housing of the rotary valve assembly and the chamber housing may be integrally connected. 
     In yet another embodiment, a method for controlling flow of a working fluid into an engine chamber using a rotary valve assembly may be provided. The rotary valve assembly may include a valve housing defining a cylindrical bore, an inlet, and an outlet. The rotary valve assembly may further include an intake assembly configured to be at least partially received within the cylindrical bore of the valve housing. The intake assembly may include an intake body defining a cylindrical bore and may have at least one intake inlet port and at least one intake chamber port. The rotary valve assembly may further include a throttle assembly configured to be at least partially received within the cylindrical bore of the intake assembly. The throttle assembly may include a throttle body defining at least one throttle inlet port and at least one throttle chamber port. The throttle assembly and the intake assembly may be concentric with respect to a longitudinal axis. The throttle assembly and the intake assembly may be configured to rotate independently of one another about the longitudinal axis. The at least one intake inlet port and the at least one throttle inlet port may at least partially overlap in the longitudinal direction. The at least one intake chamber port and the at least one throttle chamber port may at least partially overlap in a longitudinal direction. Some embodiments of the method may include receiving working fluid into the bore of the valve housing through the inlet. The intake assembly may be disposed in the bore. The method may further include rotating the intake body of the rotary valve in the bore such that the at least one intake inlet port of the inlet assembly may at least partially aligns with the inlet of the valve housing and the at least one throttle inlet port to receive the working fluid within the throttle body. In some embodiments, during the rotation of the intake body of the intake assembly, the at least one intake chamber port at least partially aligns with the at least one throttle chamber port and the outlet of the valve housing. In some embodiments, when the at least one intake chamber port, the at least one throttle chamber port, and the outlet of the valve housing at least partially align, the working fluid may be directed into the engine chamber. 
     In some embodiments, the throttle assembly may be generally stationary during rotation of the intake body, such that the intake body rotates relative to the bore of the valve housing and the throttle assembly. The throttle assembly may be configured to be rotated independently of the intake body during operation to control cutoff of the rotary valve assembly. 
     In some embodiments of the method, rotating the intake body may further include rotating the intake body at a rotational speed less than or equal to a rotational speed of an output power shaft of the engine. 
     In some embodiments, the rotary valve assembly may further include at least one throttle bearing between the intake body and the throttle body. The rotary valve assembly may include at least one seal between the at least one throttle bearing and at least one of the at least one intake inlet port, the at least one throttle inlet port, the at least one intake chamber port, or the at least one throttle chamber port. The rotary valve assembly may further include vents disposed between the at least one throttle bearing and the at least one seal. Some embodiments of the method may further include applying a vacuum via the vents between the at least one throttle bearing and the at least one seal. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1  shows an exploded view of an intake rotary valve assembly according to some embodiments discussed herein; 
         FIG. 2  shows an exploded view of an exhaust rotary valve assembly according to some embodiments discussed herein; 
         FIG. 3  shows an isometric view of an intake valve assembly according to some embodiments discussed herein; 
         FIG. 4  shows an isometric view of an intake valve assembly according to some embodiments discussed herein; 
         FIG. 5  shows an isometric view of a throttle valve assembly according to some embodiments discussed herein; 
         FIG. 6  shows an isometric view of a throttle valve assembly according to some embodiments discussed herein; 
         FIG. 7  shows an end section view of an intake rotary valve assembly according to some embodiments discussed herein; 
         FIG. 8  shows a longitudinal cross section of an intake rotary valve assembly according to some embodiments discussed herein; 
         FIG. 9  shows a longitudinal cross section of an intake rotary valve assembly according to some embodiments discussed herein; 
         FIG. 10  shows an isometric view of an exhaust rotary valve assembly according to some embodiments discussed herein; 
         FIG. 11  shows an isometric view of an exhaust rotary valve assembly according to some embodiments discussed herein; 
         FIG. 12  shows an end section view of exhaust rotary valve assembly according to some embodiments discussed herein; 
         FIG. 13  shows a longitudinal cross section of an exhaust rotary valve assembly according to some embodiments discussed herein; 
         FIG. 14  shows a longitudinal cross section of an exhaust rotary valve assembly according to some embodiments discussed herein; 
         FIG. 15  shows an isometric view of a counter flow engine according to some embodiments discussed herein; 
         FIG. 16  shows an isometric view of a semi-uniflow engine according to some embodiments discussed herein; 
         FIG. 17  shows an isometric view of a uniflow engine according to some embodiments discussed herein; 
         FIG. 18  shows a side view of a counterflow engine according to some embodiments discussed herein; 
         FIG. 19  shows a side view of a semi-uniflow engine according to some embodiments discussed herein; 
         FIG. 20  shows a side view of a uniflow engine according to some embodiments discussed herein; 
         FIG. 21  shows a cross-sectional view of a counterflow engine according to some embodiments discussed herein; 
         FIG. 22  shows a cross-sectional view of a semi-uniflow engine according to some embodiments discussed herein; 
         FIG. 23  shows a cross-sectional view of a uniflow engine according to some embodiments discussed herein; 
         FIG. 24  shows a top view of a rotary valve assembly of a counterflow or semi-uniflow engine according to some embodiments discussed herein; 
         FIG. 25  shows a top view of a rotary valve assembly of a uniflow engine according to some embodiments discussed herein; 
         FIG. 26  shows a cross-sectional view of a rotary valve assembly of a counterflow or semi-uniflow engine according to some embodiments discussed herein; and 
         FIG. 27  shows a cross-sectional view of a rotary valve assembly of a uniflow engine according to some embodiments discussed herein. 
     
    
    
     DETAILED DESCRIPTION 
     Exemplary embodiments of the present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the exemplary embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout. 
     Some embodiments detailed herein include a rotary valve assembly for use in thermal-fluid and expansion engines, including, for example, steam engines. As detailed herein, embodiments of the rotary valve assembly (e.g., rotary valve assembly  54  shown in  FIG. 1-2, 7-9, 12-14 , or  18 - 27 ) may control the flow of a working fluid (e.g., steam) under pressure into and/or out of an engine chamber to facilitate operation of a drive member (e.g., piston, rotor, etc.). The rotary valve assemblies may include one or more intake rotary valve assemblies and/or one or more exhaust rotary valve assemblies positioned in cylindrical bores of one or more valve housings. For example, some embodiments of the rotary valve assembly may be used in counter flow, semi-uniflow, and/or uniflow expansion engines. 
     The working fluid of the engine may be an organic and/or inorganic fluid, either naturally occurring or manmade. The working fluid may include, for example: Chlorofluorocarbon (CFC) (e.g. R-11, R-12); Hydrofluorocarbons (HFC) (e.g. R-134a, R-245fa); Hydrochlorofluorocarbon (HCFC) (e.g. R-22, R-123); Hydrocarbons (HC) (e.g. Butane, methane, pentane, propane, etc.); Perfluocarbon (PFC); Basic organic compounds (Carbon dioxide, etc.); Inorganic compounds (e.g. Ammonia); Elements (Hydrogen, etc.), or a combination thereof, amongst others. A preferred working liquid is steam. 
     The rotary valve assembly (e.g., rotary valve assembly  54  shown in  FIG. 1-2, 7-9, 12-14 , or  18 - 27 ) may be used with expansion engines including piston engines (e.g., uniflow, semi-uniflow, or counterflow engines), rotary engines, or other thermal-fluid expansion engines (e.g., engines  55  shown in  FIGS. 15-23 ). The rotary valve assembly may be used on any size engine regardless of number of cylinders/chambers. Most commercial engines are piston type that have four, six, or eight cylinders where each cylinder operationally houses a piston. Although some embodiments described herein may show a single valve assembly or a single piston, the rotary valve assemblies and engines may be expanded to fit any engine type or configuration. 
     Referring to  FIG. 1 , embodiments of a rotary valve assembly  54  may include an intake valve housing  10 . The intake valve housing  10  may be attached to a chamber housing, either integrally or separately mounted, as detailed herein. The intake valve housing  10  may be an integral part of a larger engine component (e.g., an engine block of engine  55  shown in  FIGS. 15-23 ) or may be separately formed and connected. 
     The intake valve housing  10  may include a bore  11  that may receive an intake valve assembly  22 . The bore  11  may be at least partially cylindrical and an outer surface of the main body (e.g., body  22   a  shown in  FIG. 3 ) of the intake valve assembly  22  may be a complementary cylindrical shape to allow the intake valve assembly to rotate within the bore of the intake valve housing. A throttle valve assembly  23  may be positioned within the intake valve assembly  22 . The intake valve assembly  22  may include a cylindrical bore, and an inner surface of the main body (e.g., body  22   a  shown in  FIG. 3 ) of the intake valve assembly may be generally cylindrical. An outer surface of the main body (e.g., body  23   a  shown in  FIG. 5 ) of the throttle valve assembly  23  may be a complementary cylindrical shape to allow relative rotation between the intake valve assembly  22  and the throttle valve assembly  23 . 
     With continued reference to  FIG. 1 , an example intake/throttle valve assembly  25 , which may include the intake valve assembly  22  and the throttle valve assembly  23 , is shown assembled. As detailed herein, one or more valve bearing/seal assemblies  40  may support the intake/throttle valve assembly  25  along a longitudinal axis of the intake/throttle valve assembly, such that the intake valve assembly  22  and throttle valve assembly  23  may both be concentric with respect to each other and the intake valve housing bore  11 . Said differently, referring to  FIGS. 8-9 , throttle valve assembly  23  may include a throttle valve body  23   a  which has an inside diameter  23   d  and outside diameter  23   e . The intake rotary valve assembly  22  may include an intake valve body  22   a  which runs complimentary along the outside diameter  23   e  of the throttle valve body  23   a  and the intake rotary valve assembly cylindrical bore  11 . The bearing/seal assemblies  40  may allow the intake valve assembly  22  and throttle valve assembly  23  to rotate within the bore  11  about the longitudinal axis. In some embodiments, the intake valve assembly may be positioned concentrically within the throttle valve assembly. 
     A retaining assembly  41  may engage an end (e.g., rear end  23   c  shown in  FIG. 5 ) the throttle valve assembly  23  and one or more of the valve bearing/seal assemblies  40 . In some embodiments, the retaining assembly may maintain and control the rotational position of the throttle valve assembly  23  to adjust the rate of flow of working fluid through the intake/throttle valve assembly  25 . 
     With reference to  FIG. 2 , a rotary valve assembly  54  may additionally or alternatively include exhaust valve housing  12  and exhaust valve assembly  24 . The exhaust valve housing  12  may be either integrally or separately attached to a chamber housing and/or the intake valve housing  10  to form an engine (e.g., engine  55  shown in  FIGS. 15-23 ). The exhaust valve housing  12  may be an integral part of a larger engine component (e.g., an engine block of the engines  55 ) or may be separately formed and connected. 
     The exhaust valve housing  12  may include a bore  13  that may receive the exhaust valve assembly,  24 . The bore  13  may be at least partially cylindrical and an outer surface of the main body (e.g., body  24   a  shown in  FIG. 10 ) of the exhaust valve assembly  24  may be a complementary cylindrical shape to allow the exhaust valve assembly to rotate within the bore of the exhaust valve housing  12 . One or more valve bearing/seal assemblies  40  may support the exhaust valve assembly  24  along a longitudinal axis of the exhaust valve assembly, such that the exhaust valve assembly may be concentric with respect to the exhaust valve housing bore  13 . The bearing/seal assemblies  40  may allow the exhaust valve assembly  24  to rotate within the bore  13  about the longitudinal axis. A retaining assembly  41  may also engage the exhaust valve assembly and retain the exhaust valve assembly  24  within the bore  13 . For example, the retaining assembly  41  may pull the exhaust valve assembly  24  or the throttle/intake valve assembly  25  rearward and maintain the valve assembly against the bearing to prevent axial movement. In some embodiments, the valve assemblies (e.g., exhaust valve assembly  24  or the throttle/intake valve assembly  25 ) may be allowed to expand forward as they heat up. 
     In some embodiments, the intake valve assembly  22  and/or the exhaust valve assembly  24  may be connected to an engine power shaft (e.g., as shown in  FIGS. 15-17 ). The intake valve assembly  22  and exhaust valve assembly  24  may rotate at a speed directly related to engine power shaft speed. In some embodiments, the intake valve assembly  22  and/or the exhaust valve assembly  24  may rotate at one half the speed of the engine output. In some embodiments, the intake valve assembly  22  and/or the exhaust valve assembly  24  may rotate at 1/N the speed of the engine output, where “N” may be any positive integer (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, etc.). With reference to  FIGS. 15-17 , example engines  55  are shown having an output power shaft  15  connected to a front end  22   b  of the intake valve assembly  22  via an intake drive belt  46  and intake valve pulley  44 . The output power shaft  15  may be connected to a front end  24   b  of the exhaust valve assembly  24  via an exhaust drive belt  47  and exhaust valve pulley  45 . The rotation of the intake valve assembly  22  and exhaust valve assembly,  24 , may be mechanically driven by the power shaft via any type of belt, pulley, chain, gear, or other drive mechanism. In some embodiments, the speed of the intake valve assembly  22  and the exhaust valve assembly  24  may be the same (e.g., the same gear ratio with respect to the output power shaft  15 ). In some embodiments, the intake valve assembly  22  and the exhaust valve assembly  24  may rotate at different speeds. 
     Referring to  FIGS. 1, 3-9, 21-23, 26, and 27 , operation of some embodiments of the intake valve/throttle valve assembly  25  will now be described more fully. In some embodiments, working fluid may be supplied to the intake valve assembly  10  through the working fluid inlet port  35  and the working fluid may fill annular volume of the bore  13  around the intake valve assembly  22 . With reference to  FIGS. 3-4, 8, and 9 , the intake valve assembly  22  may include one or more working fluid intake inlet ports  37  radially located around a circumference of the intake body  22   a . In some embodiments, the intake inlet ports  37  may be evenly distributed around the circumference of the body  22   a , to radially balance the intake valve assembly  22 . 
     In some embodiments, the intake valve assembly  22  may include at least one intake chamber port  33  per chamber of the engine. The number of intake chamber ports  33  per chamber may depend upon the rotational speed of the intake valve assembly  22  relative to the speed of the output power shaft (e.g., shaft  15  shown in  FIGS. 15-17 ) of the engine. For example, if the intake valve assembly  22  operates at the same speed of the engine, the intake valve assembly may include one intake chamber port  33  per chamber (e.g., such that the intake chamber port  33  aligns with the outlet  30  once per revolution). If the intake valve assembly  22  operates at one half the speed of the output power shaft (e.g., shaft  15  shown in  FIGS. 15-17 ), the intake valve assembly may include two intake chamber ports  33  per chamber (e.g., such that the intake chamber ports  33  align with the outlet  30  twice per revolution). In embodiments having more than one intake chamber port  33 , the intake chamber ports may be evenly distributed relative to the circumference of the intake valve body  22   a  to radially balance the intake valve assembly  22 . In some embodiments, valve speeds slower than the engine speed (e.g., half-speed, quarter-speed, etc.) may produce a naturally balanced valve assembly while allowing higher engine speeds. 
     With reference to  FIGS. 5, 6, 8, and 9 , the throttle valve assembly  23  may include throttle inlet ports  38 , radially located around the circumference of the throttle valve body  23   a . Additionally, the throttle valve assembly  23  may include at least one throttle chamber port  32 . In operation, the throttle valve assembly  23  may remain generally stationary while the intake valve assembly  22  rotates with the engine as described above. The generally stationary rotational position of the throttle valve assembly  22  may be adjusted to vary the throughput of the rotary valve assembly  54 , as discussed below. A mechanical actuator (not shown), such as a pneumatic motor or stepper motor may engage the rear end  23   c  of the throttle valve assembly  22  to control the rotational position of the throttle valve assembly  22 . As the intake valve assembly  22  rotates, the intake inlet ports  37  may align with the throttle inlet ports  38  and the working fluid inlet port  35  of the valve assembly  10 . As the ports align, the working fluid may flow into the interior of the throttle valve assembly  23 . In some embodiments, one intake valve assembly  22  and/or one throttle valve assembly  23  may be used for multiple chambers, and chamber ports for the respective chambers may be spaced along the longitudinal direction of the assemblies. In some embodiments, separate valve assemblies may be used for each chamber. 
     In some embodiments, the intake inlet ports  37  may be spaced from the intake chamber ports  33  along the longitudinal axis, such that the intake inlet ports  37  may not align with the intake housing outlet chamber port  30  and the intake chamber ports  33  may not align with the working fluid inlet port  35 . Similarly, the throttle inlet ports  38  may be spaced from the throttle chamber ports  32  along the longitudinal axis, such that the throttle inlet ports  38  may not align with the intake housing outlet chamber port  30  and the throttle chamber ports  32  may not align with the working fluid inlet port  35 . In some embodiments, the intake inlet ports  37  may at least partially overlap with the throttle inlet ports  38  and the working fluid inlet port  35  relative to the longitudinal axis, and the intake chamber ports  33  may at least partially overlap the throttle chamber ports  32  and the intake housing outlet chamber port  30  relative to the longitudinal axis. 
     Referring to  FIGS. 7, 21-23, 26, and 27 , the intake valve body  22   a  may rotate relative to the rotary valve assembly  54  and the throttle valve assembly  23  until the intake chamber port  33  aligns with the throttle chamber port  32  and the housing outlet chamber port  30  resulting in the working fluid flowing through the housing outlet chamber port  30  and into the working chamber (e.g., cylinder  49 ) of the engine  54 . In some embodiments, the intake housing outlet chamber port  30  and/or an exhaust housing inlet chamber port  31  may terminate directly within the chamber (e.g., cylinder  49 ) of the engine  54 . The throttle valve body  23   a  may be rotationally modulated (e.g., using the mechanical actuator described above) in order to vary the timing and duration of the alignment of all three ports. The throttle valve assembly  23  may be adjusted angularly about the longitudinal axis by rotating the throttle valve assembly  23  rear end  23   c , which may result in an adjustment of the duration of communication between the interior of the throttle valve body  23   a  and the cylinder head intake port  30  (e.g., due to the narrower overlap between each of the three ports  30 ,  32 ,  33 ) resulting in control of admission cutoff. The control of this admission cutoff may be used to control engine speed and/or power output. In some embodiments, intake inlet port  37  and intake chamber port  33  may be the same port. Similarly, in some embodiments throttle inlet port  38  and throttle chamber port  32  may be the same port. In some embodiments, one exhaust valve assembly  24  may be used for multiple chambers, and chamber ports for the respective chambers may be spaced along the longitudinal direction of the assemblies. In some embodiments, separate valve assemblies may be used for each chamber. 
     With reference to  FIGS. 1-6 , in some embodiments, one of the intake inlet ports  37 , one of the throttle inlet ports  38 , and the working fluid inlet port  35  may align substantially simultaneous with the alignment of one of the intake chamber ports  33 , one of the throttle chamber ports  32 , and the intake chamber outlet port  30 . In some embodiments, the inlet ports  37 ,  38 ,  35  may align at a different time than the chamber ports  32 ,  33 ,  30 . In such embodiments, the interior of the throttle valve assembly  23  may act as a reservoir for the working fluid. Similarly, in some embodiments, one exhaust port  34  and the exhaust working fluid outlet port  36  may align substantially simultaneous with the alignment of another of the exhaust ports  34  and the exhaust housing chamber inlet port  31 . In some embodiments, the exhaust outlet ports  34 ,  36  may align at a different time than the exhaust inlet ports  34 ,  31 , including in “full-speed” embodiments of the exhaust valve assembly  24  in which only one exhaust port  34  is used. 
     In some embodiments, the intake assembly  22  may include a greater number of intake inlet ports  37  than intake chamber ports  33 . In such embodiments, the intake chamber ports  33  may align with the inlet  30  of the intake valve housing  10  at predetermined intervals based on the engine timing, as discussed herein, and the intake inlet ports  37  may communicate with the working fluid inlet  35  one or more times per engine cycle to receive the working fluid. Similarly, the throttle assembly  23  may include a greater number of throttle inlet ports  38  than throttle chamber ports  32 . 
     In some embodiments, the intake assembly  22  may include one or more times (e.g., one, two, three, four, five, six, etc. times) the number of intake chamber ports  33  as throttle chamber ports  32  in the throttle assembly  23 . In some embodiments, as discussed herein, the throttle assembly  23  may be generally stationary during operation and may be slightly adjusted to control cutoff of the rotary valve assemblies  54 . In such embodiments, the throttle assembly  23  may include one throttle chamber port  32 . 
     In reference to  FIGS. 2, 10, and 11 , the exhaust valve assembly  24  may include at least one exhaust port  34  per working chamber of the engine. The number of exhaust ports  34  per chamber may depend upon the rotational speed of the exhaust valve assembly  24  relative to the speed of the output power shaft (e.g., shaft  15  shown in  FIGS. 15-17 ) of the engine. For example, if the exhaust valve assembly  24  operates at the same speed of the engine, the exhaust valve assembly may include one exhaust port  34  per chamber. If the exhaust valve assembly  24  operates at one half the speed of the output power shaft (e.g., shaft  15  shown in  FIGS. 15-17 ), the exhaust valve assembly may include two exhaust ports  34  per chamber of the engine. In embodiments having more than one exhaust port  34 , the exhaust chamber ports may be evenly distributed relative to the circumference of the exhaust valve body  24   a  to radially balance the exhaust valve assembly  24 . In some embodiments, valve speeds slower than the engine speed (e.g., half-speed, quarter-speed, etc.) may produce a naturally balanced valve assembly. 
     In some multi-chamber embodiments detailed herein, the working fluid in the exhaust and intake assemblies may travel axially between the ports of different chambers (e.g., to exhaust working fluid from the valve or intake working fluid to the valve when one or more of the ports are closed). In some embodiments, dedicated exhaust outlet ports may be provided to communicate the exhaust valve assembly  24  with the exhaust working fluid outlet  30  more frequently, as shown with respect to the intake working fluid ports  37  and throttle working fluid ports  38 . 
     Referring to  FIGS. 12, 21, 22, and 26 , the exhaust valve body  24   a  may rotate until the exhaust chamber port  34  aligns with the exhaust housing inlet chamber port  31 . When the ports are aligned, the working fluid may flow out of the chamber of the engine  55  and into the interior of the exhaust valve assembly  24  through the exhaust housing inlet chamber port  31 . The working fluid may then exit the exhaust valve assembly  24  through the exhaust port  34  and flow into the exhaust valve housing  12 . The working fluid may exit the exhaust valve housing  12  through exhaust working fluid port  36 . In some embodiments, the working fluid may exit the exhaust valve through a dedicated exhaust working fluid port instead of through exhaust port  34 . 
     In some embodiments, the ports (e.g., any of ports  30 - 38 ) may be generally rectangularly shaped. As detailed herein, the term “generally rectangular” may include four sides arranged substantially perpendicularly and may include rectangles with rounded corners and/or tapered wall sections. In such embodiments, the rectangular shape of the ports may include a long dimension and a short dimension, in which the long dimension may be longer than the short dimension and oriented parallel to the longitudinal axis and the short dimension may be oriented circumferentially for ports disposed on one of the valve assemblies. Rectangularly shaped ports may allow for efficient opening and closing of the valves, and the longer edge in the long dimension may be perpendicular to the direction of rotation of the surface of the valves, such that the straight leading longer edges and trailing longer edges of the valves may allow for precise, quick, and efficient opening and closing during rotation. In some embodiments rectangularly shaped ports may also improve the cost efficiency of manufacturing the valves. 
     Referring to  FIGS. 3-6, 8, and 9 , the intake valve assembly  22  front end  22   b  may support the front of the intake valve body  22   a , and the intake valve assembly  22  rear end  22   c  may support the rear of the intake valve body  22   a . These components may be connected together by known fasteners such as bolts, screws, cross pins, welding, and other connectors known in the art. The intake valve assembly front end  22   b  and rear end  22   c  may be supported by one or more bearings  27  operably mounted to the intake valve housing  10 . In some embodiments, the bearings  27  may aligned concentrically with the intake rotary valve assembly  22  and the intake valve housing cylindrical bore  11  along the longitudinal axis to allow the intake rotary valve/throttle assembly  25  to rotate within the bore. The valve bearings  27  may provide support to the rotary valve/throttle assembly  25  in the radial and/or axial directions. With reference to  FIG. 9 , in some embodiments, a bushing may be operably mounted to the intake valve housing  10 , and the bushing may be concentrically aligned on the longitudinal axis with the intake valve assembly  22  and throttle valve assembly  23 . In some embodiments, the bushing may support the rear end  23   c  of the throttle valve assembly  23 . The bushing may be used instead of or in addition to a throttle bearing  29  to support and maintain the throttle valve assembly in a generally stationary position, which may be adjustable, while the intake valve assembly  22  rotates with the engine. 
     In some embodiments, seals  26  (e.g., rotary lip seals) may be disposed between the working fluid inlet  35  and the bearings  27  to protect the bearings  27  from the working fluid.  FIG. 8  illustrates the optional use of multiple valve bearings  27  for reduced deflection of the intake valve/throttle assembly  25  due to additional moment reaction in the valve assemblies. For example, multiple bearings  27  may be positioned on one or both ends  22   b ,  22   c  of the intake valve assembly  22  to stabilize the valve  22  in the radial and/or axial directions. 
     In some embodiments, leakage vents  39  may allow working fluid that leaks past the seals to escape and not compromise the integrity of the valve bearings  27 . In some further embodiments, a vacuum may be applied at the vents  39  between one or more of the seals  26  and one or more of the bearings  27  to improve the longevity of the bearings. The vacuum may be applied by pump or similar device (not shown), which may be powered by the engine  55  or by an external source. The valve bearings  27  may provide both radial and axial support. A retainer  41  is used to control thrust. In some embodiments, the retainer  41  may be a bearing nut. In some embodiments, the retainer  41  may be c-clips, pins or other retaining mechanisms. 
     The intake rotary valve assembly  22  may accommodate and receive the throttle valve assembly  23  therein. The throttle valve assembly  23  front end  23   b  may supported by at least one throttle bearing  29  positioned at the intake rotary valve assembly  22  front end  22   b  between at least a portion of the intake rotary valve assembly  22  and the throttle valve assembly  23 . Similarly, the rear end  23   c  of the throttle valve assembly  23  may be supported by at least one throttle bearing  29  positioned at the intake valve assembly rear end  22   c  between at least a portion of the intake rotary valve assembly  22  and the throttle valve assembly  23 . Multiple throttle bearings  29  may be positioned at each end to improve moment reaction and reduced deflection of throttle valve assembly  23 . The throttle bearings  29  may serve as support in the radial and/or axial direction. In some embodiments, seals  28  (e.g., rotary lip seals) may prevent working fluid leakage and protects the throttle bearings  29  from the working fluid. The vents  39  communicate to ports in the throttle valve assembly in order to evacuate working fluid that leaks past the seals  28 . As detailed above, a vacuum may also be applied at the vents between one or more of the seals  28  and one or more of the throttle bearings  29  to reduce damage to and improve the longevity of the bearings. In some embodiments, the vents  39  may simultaneously fluidly connect a space between the valve bearings  27  and seals  26  and between the throttle bearings  29  and the seals  28 , and the vents  39 , via a pump or other mechanism, may apply a vacuum therebetween. 
     Referring to  FIGS. 10, 11, 13, and 14 , the exhaust valve assembly front end  24   b  may support the front of the exhaust valve body  24   a , and the exhaust valve assembly rear end  24   c  may support the rear of the exhaust valve body  24   a . These components may be operably connected, such as by bolts, screws, cross pins, welding, or other attachment mechanisms known in the art. The exhaust valve assembly front end  24   b  and rear end  24   c  may be supported within the cylindrical bore  13  by at least one bearing  27  mounted to the exhaust valve housing  12 , such that the exhaust valve assembly  24  may be concentrically disposed within the bore and may be able to rotate about the longitudinal axis. The bearings  27  may support the exhaust valve assembly  24  in the radial and/or axial direction. 
     In some embodiments, seals  26  (e.g., rotary lip seals) may be disposed between the working fluid exhaust  36  and the bearings  27  to protect the bearings from the working fluid. With reference to  FIG. 13 , an example exhaust valve assembly  24  is shown having multiple valve bearings  27  for reduced deflection of the exhaust valve assembly  24  cause by the additional moment reaction of the valve assemblies. 
     In some embodiments, leakage vents  39  may allow working fluid that leaks past the seals  26  to escape and not compromise the integrity of the valve bearings  27 . In some further embodiments the vents  39  may be vented to vacuum, such that a vacuum is applied between one or more of the seals  26  and one or more of the bearings  27 . The vacuum may be applied by pump or similar device (not shown), or may be applied by negative pressure in the engine which may be created by the drive elements (e.g., piston  50 ) in the chamber (e.g., cylinder  49 ). The valve bearings  27  may provide both radial and axial support to the exhaust valve assembly  24 . The retainer  41  may be used to control and support the axial direction of the exhaust valve assembly. In some embodiments, the retainer  41  may be a bearing nut. In some embodiments, the retainer may include c-clips, pins or other retaining mechanisms. 
     As detailed above, the rotary valve assemblies  54  discussed herein may be attached to an expansion-driven engine. With reference to  FIGS. 15-27 , in some embodiments, the rotary valve assembly may include one or more intake valve housings  10 , which may include one or more intake valve assemblies  22  and/or throttle assemblies  23 , and one or more exhaust valve housings  12 , which may include one or more exhaust valve assemblies  24 . The rotary valve assemblies may receive working fluid (e.g., steam) under pressure from a boiler, compressor, and/or other source at the working fluid inlet port  35  for driving the engine, which may convert the pressure of the working fluid into mechanical work. As detailed herein, the rotary valve assemblies, including one or more of the intake valve housings  10  and/or exhaust valve housings  12  may be attached, either integrally or by a fastening device such as a bolt, screw, adhesive, welding, or other known attachment means, to an engine chamber housing  48 . In some embodiments the rotary valve assemblies  54  may be rigidly attached directly and/or integrally to the engine chamber housing  48 , and in some embodiments, a gasket, seal, or other device may be positioned between the rotary valve assemblies  54  and the engine chamber housing  48 . However, in either event, the rotary valve assemblies  54  and chamber housing  48  may be said to be rigidly attached. 
     For example, some embodiments of the engine may include a linear piston-driven engine as shown in  FIGS. 21-23 . In some embodiments, the engine may include any desired number of cylinders, including but not limited to one, two, four, six, or eight cylinders. Referring to  FIGS. 21-23 , for example purposes, the engine  55  is shown having a single cylinder  49 . In some embodiments, the working fluid (e.g., steam) is distributed to the engine at the working fluid inlet port  35 , and may be distributed through the engine  55  by the rotary valve assemblies  54 . With reference to  FIGS. 17, 20, and 23 , a uniflow engine receives working fluid at the working fluid inlet port  35  and applies the working fluid to the engine chamber (e.g., cylinder  49 ) to actuate the drive member (e.g., piston  50 ). With reference to  FIG. 23 , when the piston  50  passes below the cylinder wall exhaust port  52 , the working fluid may enter the cylinder wall exhaust port  52  and exit the engine through exhaust ports  51 . 
     With reference to  FIGS. 16, 19, and 22 , an example of a semi-uniflow engine is shown. A semi-uniflow engine may receive working fluid at the working fluid inlet port  35  and may apply the working fluid to the engine chamber (e.g., cylinder  49 ) to actuate the drive member (e.g., piston  50 ). The semi-uniflow engine may then exhaust working fluid through at least two exhaust ports  36 ,  39 . With reference to  FIG. 22 , when the piston  50  passes below the cylinder wall exhaust port  52 , the working fluid may enter the cylinder wall exhaust port  52  and exit the engine through exhaust ports  51 . The semi-uniflow engine may exhaust working fluid remaining in the cylinder through exhaust port  36  via the exhaust valve assembly  24  as detailed above. 
     With reference to  FIGS. 15, 18, and 21 , an example of a counterflow engine is shown. A counterflow engine may receive working fluid at the working fluid inlet port  35  and may apply the working fluid to the engine chamber (e.g., cylinder  49 ) to actuate the drive member (e.g., piston  50 ). The counterflow engine may then exhaust working fluid through the exhaust outlet  36  using an exhaust assembly  24 . 
     In some embodiments, the engine  55  may open the respective exhaust systems (e.g., exhaust ports  34  may communicate with exhaust housing chamber inlet port  31  and/or a portion of the chamber  49  holding the working fluid may be exposed to outlets  51 ) with respect to the chamber (e.g., cylinder  49 ) to allow the working fluid to exit the chamber at approximately the maximum volume of the chamber (e.g., near or at the maximum downstroke of the piston  50  in the embodiment of  FIGS. 21-23 ), and the engine may close the respective exhaust systems at some point before the minimum volume of the chamber (e.g., the maximum upstroke of the piston  50  in the embodiments of  FIGS. 21-23 ). In some embodiments, the engine may open the intake system (e.g., intake valve assembly  22  and throttle valve assembly  23 ) with respect to the chamber  49  to allow the working fluid to enter the chamber at approximately the minimum volume of the chamber (e.g., the maximum upstroke of the piston  50  in the embodiments of  FIGS. 21-23 ), and the engine may close the intake system at a throttle valve controlled point, which may be before the maximum volume of the chamber (e.g., near or at the maximum downstroke of the piston  50  in the embodiment of  FIGS. 21-23 ). 
     Similarly, a rotary valve assembly  54  including an intake/throttle assembly  25  (e.g., including intake assembly  22  and throttle assembly  23 ) and/or an exhaust assembly  24  may be either integrally or separately attached to a rotary engine. 
     In some embodiments, whether a counterflow, semi-uniflow, uniflow, or rotary type engine, the exhaust from exhaust port (e.g., exhaust ports  36 ,  39 ) may be fed into the working fluid inlet port  35  of another engine or to the working fluid inlet port  35  of another cylinder of a multiple cylinder engine. In some embodiments, working fluid may be simultaneously fed into two or more engines and/or cylinders in parallel. Any number of cylinders and/or engines may be connected and combined in either series or parallel as described herein. 
     With reference to  FIGS. 15-20  a belt drive system may be used in the engines to transmit mechanical energy throughout the system. As detailed above, the intake rotary valve assembly  22  and/or the exhaust rotary valve assembly  24  may be driven by at least one main output power shaft  15 . The power shaft  15  in piston-operated embodiments may be a crankshaft or similar mechanism that may convert reciprocating motion into rotational motion. In such embodiments, the linear motion of a reciprocating piston  50  may be converted to rotational movement at the main power shaft  15  by a crank-slider mechanism  17  or other similar mechanism. The crank-slider mechanism  17  is comprised of at least one connecting rod  16  transmitting force between the main power shaft  15  and the reciprocating piston  50 . 
     Power from the output power shaft  15  may be transmitted to the intake rotary valve assembly  22  and/or the exhaust rotary valve assembly  24  via corresponding intake drive belts  46  and/or exhaust drive belts  47 , respectively. A primary drive pulley  43  may be operationally attached at an end of the output power shaft  43  to receive the intake drive belts  46  and/or exhaust drive belts  47 . An intake valve pulley  44  may be operationally attached at the front end  22   b  of the intake rotary valve assembly  22 , and an exhaust valve pulley  45  may be operationally attached at the front end  24   b  of the exhaust rotary valve assembly  24 , such that the intake valve pulley  44  may receive torque from the intake drive belt  46  and the exhaust valve pulley  45  may receive torque from the exhaust drive belt  47 . In some embodiments, a chain, gear, hydraulic or electric motor, or other similar system may be used to transmit torque to the rotary valve assemblies. 
     Referring to  FIGS. 15-23 , the rotary valve assembly  54  may be either integrally or separately operationally attached to a chamber housing  48  (e.g., a cylinder block). The chamber housing  48  may include at least one chamber (e.g., at least one cylinder  49 ) which is comprised of at least one drive element (e.g., reciprocating piston  50 ). For semi-uniflow and uniflow engines, the chamber (e.g., cylinder  49 ) includes ports  52  in the wall. 
     Many modifications and other embodiments of the inventions set forth herein will come to mind to one skilled in the art to which these embodiments of the invention pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the embodiments of the invention are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. While some drawings and description may omit features described elsewhere for simplicity of explanation, it is understood that these features may nonetheless be present in any of the embodiments in any combination or configuration, as detailed above. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.