Patent Publication Number: US-2016230605-A1

Title: Practical steam engine

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
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     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
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     INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC 
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     BACKGROUND OF INVENTION 
     Low grade fuels (low density, low heating value solid, liquid and gaseous substances) are not competitive with higher grade commercial fuels in small scale (e.g., less than 2000 kW) mobile and stationary power plants. This is mainly due to the lack of small scale, efficient, low cost steam prime movers that can economically convert low grade fuels into usable, industrial power. 
     The traditional reciprocating steam engine, in its various forms, has become economically and technologically obsolete due to the availability of refined, petroleum based fuels that were better utilized in more efficient heat engine cycles (Otto, Diesel and Brayton cycles) and the development of low cost electrical power delivered by the interconnected utility power grid. The traditional steam engine is limited by its ability to convert raw, unrefined fuel sources into clean, high quality steam energy that is converted to mechanical work. The final evolution of reciprocating steam engine technology circa 1950 is represented by the uniflow steam engine. The first American uniflow engine was built in 1913 by the Skinner Engine Company of Erie, Pa.; the last one was built in 1982. The Skinner Engine Company closed its doors and was liquidated in 2003. 
     The Skinner Universal Uniflow steam engine, circa 1950, represents the current state of the art for commercially manufactured, industrial steam engines applied to stationary service. The Skinner Uniflow steam engine was a major improvement over previous engine types because it improved steam flow dynamics and thermal efficiency. But it could only work at relatively low speeds (e.g., generally not exceeding 400 rpm). Thus, it required high torque outputs. The result is that the Skinner Uniflow engine had five major weaknesses: (a) massive and costly components that could not withstand high reaction forces generated by large piston diameters due to low rotational speeds (generally not above 400 rpm); (b) double acting pistons required complex piston rod/crosshead/connecting rod assemblies that limited rotational speeds due to high inertia forces that could not be adequately balanced at high speed; (c) long cutoffs of up to 40% that adversely impacted thermodynamic performance; (d) need for large concrete foundations to support the heavy engine weights and separate condenser, and, therefore, lack of portability; and (e) higher cost compared to less efficient steam turbines due to higher manufacturing and labor costs. 
     A compact, thermodynamically and power efficient steam engine that runs at higher speeds, and therefore, requires lower torque outputs, has smaller components and does not require a massive support foundation is unknown in the prior art. 
     SUMMARY OF INVENTION 
     The present invention is directed to a Practical Steam Engine that can run at higher speeds (at least 400 rpms) and, thus, requires lower torque outputs. This lower torque output, in turn, allows the power delivery through smaller components that do not need to be supported by a massive concrete foundation as does the prior art uniflow engine. The fact that the Practical Steam Engine can be made compactly and relatively portable makes it ideal for off-grid power generation applications. The Practical Steam Engine may be fueled by biomass, such as slash and thinnings as part of forest management practices, or for providing steam-generated power at a merchantable timber source to add value to wood product processes. 
     The Practical Steam Engine includes at least one cylinder head assembly, an admission and exhaust valve assembly, a cylinder/piston assembly, a crank shaft assembly or other similar apparatus that converts between reciprocating motion and rotational motion, a valve gear assembly. The admission or the exhaust valve assembly, or both the admission and exhaust valve assembly includes a variable duration, rotary valve (the “rotary valve”). The rotary valve eliminates reciprocating motion reducing the number of moving components therefore reducing the failure rate of mechanical components. Another advantage of the rotary valve is that it, in its typical motion, does not move in a direction significantly affected by the forces of net pressure forces of the working fluid, a common problem experienced by poppet-valves and slide valves conventionally used in these types of engines. 
     When the Practical Steam Engine is placed into a conventional Rankine cycle with an evaporator (boiler), condenser, and pumps, the overall energy generation plant may produce mechanical work using raw, unrefined fuel sources such as biomass (e.g., residual forest waste) and other unconventional fuel sources, as well as conventional fuel sources. The Practical Steam Engine steam-powered generator is more compact in size than prior art. For example, The Practical Steam Engine may, for example, be transported to remote areas, particularly where remotely-accessed biomass may be located. This cuts down on the high cost and pollution from using conventional fuel sources (e.g., Diesel oil) to transport the biomass to the Practical Steam Generator. This compact-size steam generator using the Practical Steam Engine can be utilized within deep forests as part of forestry management or at a merchantable timber source to allow value-added processing at or closer to the power source (such as at sawmills, or wood palletizing and pulp chipping). Further, the Practical Steam Engine may be used to produce higher value wood processed products closer to the power source, thereby reducing transportation logistics, costs and additional carbon emissions from such transportation. 
     The single acting, simple expansion design of the Practical Steam Engine lends itself to conversion of a counter flow, semi-uniflow or uniflow engine to a counter flow, semi-uniflow, or uniflow engine for steam operation. The conversion process replaces a cylinder head, including the poppet valves, of a conventional engine with a cylinder head having an integral valve assembly. The resulting converted engine to steam engine operates at high volumetric efficiency. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       Other features and advantages of the present invention will become apparent in the following detailed descriptions of the preferred embodiment with reference to the accompanying drawings, of which: 
         FIG. 1  is an isometric view of an exemplary counterflow engine; 
         FIG. 2  is an isometric view of an exemplary semi-uniflow engine 
         FIG. 3  is an isometric view of an exemplary uniflow engine; 
         FIG. 4  is a side view of an exemplary counterflow engine; 
         FIG. 5  is a side view of an exemplary semi-uniflow engine; 
         FIG. 6  is a side view of an exemplary uniflow engine; 
         FIG. 7  is a section view of an exemplary counterflow engine (section  1 - 1 ) taken from  FIG. 4 ; 
         FIG. 8  is a section view of an exemplary semi-uniflow engine (section  2 - 2 ) taken from  FIG. 5 ; 
         FIG. 9  is a section view of an exemplary uniflow engine (Section  3 - 3 ) taken from  FIG. 6 ; 
         FIG. 10  is a top view of dual valve head assembly for exemplary counterflow engine and semi-uniflow engine; 
         FIG. 11  is a top view of single valve head assembly for an exemplary uniflow engine; 
         FIG. 12  is a section view of intake valve assembly as used in exemplary counterflow engine, semi-uniflow engine and uniflow engine (section  4 - 4 ) taken from  FIG. 11 ; 
         FIG. 13  is a section view of exhaust valve assembly as used in exemplary counterflow engine and semi-uniflow engine (section  5 - 5 ) taken from  FIG. 10 ; 
         FIG. 14  is a section view of cylinder head assembly as used in exemplary counterflow engine and semi-uniflow engine (section  6 - 6 ) taken from  FIG. 10 ; 
         FIG. 15  is a section view of cylinder head assembly as used in an exemplary uniflow engine (section  7 - 7 ) taken from  FIG. 11 ; 
         FIG. 16  is an isometric view of intake valve assembly as used in exemplary counterflow engine, semi-uniflow engine and uniflow engine; 
         FIG. 17  is an isometric view of exhaust valve assembly as used in exemplary counterflow engine and semi-uniflow engine; 
         FIG. 18  is an isometric view of adjustment valve assembly as used in exemplary counterflow engine, semi-uniflow engine and uniflow engine. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, may be embodied in many different forms and should not be construed as limited to the embodiments set for herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. The current invention is a high speed, two-stroke engine that is counter flow, semi-uniflow, or uniflow and is comprised of at least one variable rotary valve mechanism. Working fluid, referred to herein, may be organic and/or inorganic fluid, naturally occurring and/or man-made. Working fluid may include: Chlorofluorocarbon (CFC) (e.g. R-11, R-12); Hydro-fluorocarbons (HFC) (e.g. R-134a, R-245fa); Hydro-chlorofluorocarbon (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 water. 
     Most commercial engines have four, six, or eight cylinders where each cylinder operationally houses a piston. The current invention may have a conventional number of cylinders however; it must have at least one cylinder. Referring to  FIGS. 1, 2, 3 , for exemplary purposes, the Practical Steam Engine  10  is illustrated as an engine having a single cylinder. Working fluid is distributed to the engine at  35  by an intake rotary valve assembly  22 . Referring to  FIGS. 1, 4, 7 , in a counterflow engine working fluid exits the engine through at least one exhaust port  36  which is regulated by an exhaust rotary valve assembly  24 . Referring to  FIGS. 2 ,  5 ,  8 , in a semi-flow engine working fluid exits the engine through at least two exhaust ports  36  and  39 . Preferably, the exhaust port  39  exhausts working fluid from at least one cylinder wall exhaust port  40  when the piston  14  travels below the cylinder wall exhaust ports  40 . Referring to  FIGS. 3, 6, 9 , in a uniflow engine working fluid exits the engine through exhaust port  39  from wall port  40  when the piston  14  travels below the cylinder wall exhaust ports  40 . In one embodiment, whether a counterflow, semi-uniflow or uniflow type engine, the exhaust from exhaust port ( 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. 
     Referring to  FIGS. 1, 2, 3 , preferably, a belt drive system is used to transmit mechanical energy. More specifically, the intake rotary valve assembly  22  and exhaust rotary valve assembly  24  are driven by at least one main power shaft  15 . The power shaft  15  may be a crankshaft or similar mechanism that converts between reciprocating motion and rotational motion. Torque is transmitted to the intake drive belt  41  and exhaust drive belt  42  from the power shaft  15  via a primary drive pulley  43 . The intake drive belt  41  and exhaust drive belt  42  transmits torque to the intake rotary valve assembly  22  and exhaust rotary valve assembly  24  by through an intake valve pulley  44  and exhaust valve pulley  45 . The intake valve pulley  44  and the exhaust valve pulley  45  are operationally attached to the intake rotary valve assembly  22  front end  22   b  and exhaust rotary valve assembly  24  front end  24   b , respectively. Alternatively, a chain, gear, hydraulic, electric or other similar system may be used to transmit torque through the system. 
     Referring to  FIGS. 1-6 and 14, and 15 , the cylinder head assembly  11  is operationally attached to a cylinder block  12 . The cylinder block  12  houses at least one cylinder  13  which is comprised of at least one reciprocating piston  14 . The linear motion of the reciprocating piston  14  is 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  which transmits force between the main power shaft  15  and the reciprocating piston  14 . 
     Referring to  FIG. 14 , preferably, in a semi-uniflow engine the interior of the cylinder head assembly  11  is comprised of an intake rotary valve assembly cylindrical bore  20 , and an exhaust rotary valve assembly cylindrical bore  21 . Referring to  FIG. 15 , preferably, in a uniflow engine the interior of the cylinder head assembly  11  is comprised of an intake rotary valve cylindrical bore  20 . Referring to  FIG. 14 , preferably, in a counter-flow engine the interior of a cylinder head assembly is comprised of an intake rotary valve assembly cylindrical bore  20  and exhaust rotary valve assembly cylindrical bore  21 . The inside diameter of the intake rotary valve assembly  22  receives an adjustment valve assembly  23 . 
     Referring to  FIG. 18 , the adjustment valve assembly  23  is comprised of an adjustment tube  23   a  which has an inside diameter  23   d  and outside diameter  23   e . Referring to  FIGS. 12 and 16 , the intake rotary valve assembly  22  is comprised of an intake tube  22   a  which runs complimentary along the outside diameter  23   e  of the adjustment tube  23   a  and the intake rotary valve assembly cylindrical bore  20 . The adjustment valve assembly  23  communicates with the intake rotary valve assembly  22  via adjustment valve port  32 . The intake rotary valve assembly  22  communicates with the cylinder via intake valve cylinder port  33  and cylinder head intake port  30 . Contained within the exhaust valve cylindrical bore  21  is the exhaust rotary valve assembly  24 . Referring to  FIGS. 13 and 17 , the exhaust rotary valve assembly  24  communicates with the cylinder  13  via exhaust tube port  34  and cylinder head exhaust port  31 . 
     Referring to  FIGS. 12 and 16 , the intake rotary valve assembly  22  is turned by the intake valve assembly  22  front end  22   b  which is driven by the power shaft  15  of the engine. The intake valve assembly  22  front end  22   b  supports the front of the intake valve tube  22   a  and the intake valve assembly  22  rear end  22   c  supports the rear of the intake valve tube  22   a . These components are connected together by known fasteners such as bolts, screws, cross pins, amongst others. The intake valve assembly front end  22   b  is supported by a bearing  25  operably mounted to the cylinder head assembly  11 . Preferably, the bearing  25  is aligned concentrically to the intake rotary valve assembly  22  cylindrical bore  20 . Known seals protect the bearings  25  from the working fluid; preferably, the seals are rotary lip seal  26 . 
     The intake rotary valve assembly  22  accommodates the adjustment valve assembly  23 . The adjustment valve assembly  22  front end  23   b  is supported by a bearing  27  mounted to the intake rotary valve assembly  22  front end  22   b . Similarly, the rear end  23   c  of the adjustment valve assembly  23  rear end is supported by a bearing  27  located to the intake valve assembly rear end  22   c . Additionally, a stationary bushing  28  is operably mounted to the cylinder head assembly  11 . Preferably, the stationary bushing  28  is aligned concentrically with the intake rotary valve assembly cylindrical bore  20 , and supports the rear end  23   a  of the adjustment valve assembly  23 . Known seals prevent working fluid leakage and protects the valve bearing  25  from the working fluid; preferably, the seal is a rotary lip seals  29 . 
     Working fluid is supplied through the working fluid inlet port  35  and fills the cylinder head annular volume around the intake valve assembly  22 . The working fluid travels through working fluid ports  37 , radially located around the circumference of the intake valve tube  22   a . As the intake valve assembly  22  rotates, these ports align with adjustment tube working fluid ports  38 , radially located around the circumference of the adjustment valve tube  23   a , thus supplying working fluid to the interior of the adjustment valve tube  23   a . When the intake valve cylinder ports  33  and adjustment valve cylinder ports  32  align as described in  FIG. 7 , the working fluid is admitted to the cylinder. The adjustment valve angular position, as described in  FIG. 7 , may be varied by providing external rotational force to the adjustment valve rear end  23   c  on the shaft protruding from the rear of the cylinder head assembly. 
     Referring to  FIGS. 13 and 17 , the exhaust valve assembly front end  24   b  supports the front of the exhaust valve tube  24   a  and the exhaust valve assembly rear end  24   c  supports the rear of the exhaust valve tube  24   a . These components are operably connected by known fasteners such as whether bolts, screws, cross pins, amongst others. The exhaust valve assembly front shaft is supported by a bearing  25  mounted to the cylinder head assembly  11 , located concentrically to the exhaust rotary valve assembly cylindrical bore  21 . Preferably, the exhaust valve assembly front shaft is supported by a bearing  25  mounted to the cylinder head assembly  11 , located precisely concentrically to the exhaust rotary valve assembly cylindrical bore  21 . Any known seal can protect the bearing  25  from the working fluid; preferably, rotary lip seals  26  are used. 
     Once exhaust working fluid leaves the cylinder  13  and is delivered to the interior of the exhaust valve tube  24   a  through the exhaust tube port  34 , the exhaust rotary valve assembly  24  rotates until the exhaust tube port  34  aligns with the primary exhaust port  36 . The intake rotary valve assembly  22  rotates at a speed directly related to the engine speed. The intake rotary valve assembly  22  may rotate at the same speed of the engine, one-half the engine speed, one-third of the engine speed, etc. Preferably, the intake rotary valve assembly  22  rotates at one-half engine speed. When the working fluid inlet port  38  aligns with the cylinder head intake port  30  and the adjustment valve cylinder port  32 , working fluid is allowed into the interior of the adjustment valve tube  23   a  to be supplied to the cylinder  13  via the cylinder head intake port  30 . 
     The adjustment valve assembly  23  may be adjusted angularly by rotating the adjustment valve assembly  23  rear end  23   c  by adjusting the duration of communication between the interior of the adjustment valve tube  23   a  and the cylinder head intake port  30 , resulting in control of admission cutoff. The control of this admission cutoff may be used to control engine speed and/or power output. The exhaust valve tube  24   a  also rotates at a speed directly related to engine speed. The exhaust rotary valve assembly  24  may rotate at the same speed of the engine, one-half the engine speed, one-third of the engine speed, etc. Preferably the exhaust rotary valve assembly  24  rotates one-half the speed of the engine. As the exhaust valve tube  24   a  rotates, the exhaust tube port  34  aligns with the cylinder head exhaust port  31 . Working fluid is exhausted from the cylinder  13  into the interior of the exhaust valve tube  24   a . When the exhaust tube port  34  aligns with the primary exhaust port  36 , working fluid is exhausted from the interior of the exhaust valve, thus allowing exhaust working fluid to exit the cylinder head assembly  11  and subsequently the engine  10 . Preferably, both the intake valve tube  22   a  and the exhaust valve tube  24   a  may utilize diametrically opposed cylinder ports, thus producing an inherently radially balanced valve. Preferably the intake valve  22  and the exhaust valve  24  operate at precisely one-half engine speed—increasing bearing life. 
     Referring to  FIG. 12 , the intake rotary valve assembly  22  is comprised of: an intake valve tube  22   a , a front end  22   b  and a rear end  22   c . The front end  22   b  and the rear end  22   c  are operably connected to the intake valve tube  22   a  via known fasteners such as bolts, screws, cross pins, amongst others. The intake valve tube  22   a  includes at least one cylinder port  33  and at least one working fluid inlet port  37 . 
     Referring to  FIG. 9 , the exhaust rotary valve assembly  24  is comprised of: an exhaust valve tube  24   a , a front end  24   b  and a rear end  24   c . The front end  24   b  and the rear end  24   c  are operably connected to the exhaust valve tube  24   a  via known fastening methods such as bolts, screws, cross pins, welded, amongst others. The exhaust valve tube  24   a  includes at least one tube port  34 . 
     Referring to  FIG. 10 , the adjustment valve assembly  23  is comprised of the following components: an adjustment valve tube  23   a , a front end  23   b  and a rear end  23   c . The front end  24   b  and the rear end  24   c  are operably connected to the adjustment valve tube  23   a  via known fastening methods such as bolts, screws, cross pins, welded, amongst others. The adjustment valve tube  23   a  includes at least one cylinder port  32  and at least one working fluid inlet port  38 .