Abstract:
A rechargeable pneumatic reciprocating piston engine that uses a mixture of compressed air and water as the working fluid with a combination of gravity and spring force functioning to return the piston after completion of the power stroke whereafter repeated power strokes may be achieved from a single charge of compressed fluid thereby providing a rechargeable pneumatic engine capable of running for an extended period of time on a single charge is disclosed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation-in-part of U.S. patent application Ser. No. 12/207,606, filed on Sep. 10, 2008. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    N/A 
       COPYRIGHT NOTICE 
       [0003]    A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or patent disclosure as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all rights whatsoever. 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    The present invention relates generally to reciprocating piston engines, and more particularly to a rechargeable pneumatic engine wherein a mixture of compressed air and water functions as the working fluid, with a combination of gravity and spring force functioning to return the piston after completion of the power stroke. 
         [0006]    2. Description of Related Art 
         [0007]    An internal combustion engine is one in which combustion of the fuel takes place in a confined space, producing expanding gases that are used directly to provide mechanical power. Such engines are classified as reciprocating or rotary, spark ignition or compression ignition, and two-stroke or four-stroke. The most familiar combination is the reciprocating, spark-ignited, four-stroke gasoline engine, commonly found in automobiles. 
         [0008]    The first person to experiment with an internal-combustion engine was the Dutch physicist Christian Huygens, about 1680. But no effective gasoline-powered engine was developed until 1859, when the French engineer J. J. Étienne Lenoir built a double-acting, spark-ignition engine that could be operated continuously. In 1862 Alphonse Beau de Rochas, French scientist, patented but did not build a four-stroke engine; sixteen years later, when Nikolaus A. Otto built a successful four-stroke engine, it became known as the “Otto cycle.” The first successful two-stroke engine was completed in the same year by Sir Donald Clerk, in a form which (simplified somewhat by Joseph Day in 1891) remains in use today. In 1885 Gottlieb Daimler constructed what is generally recognized as the prototype of the modern gas engine: small and fast, with a vertical cylinder, it used gasoline injected through a carburetor. In 1889 Daimler introduced a four-stroke engine with mushroom-shaped valves and two cylinders arranged in a V, having a much higher power-to-weight ratio; with the exception of electric starting, which would not be introduced until 1924, most modern gasoline engines are descended from Daimler&#39;s engine. 
         [0009]    The most common internal-combustion engine is the piston-type gasoline engine used in most automobiles. The confined space in which combustion occurs is called a cylinder. The cylinders are now usually arranged in one of four ways: a single row with the centerlines of the cylinders vertical (in-line engine); a double row with the centerlines of opposite cylinders converging in a V (V-engine); a double zigzag row somewhat similar to that of the V-engine but with alternate pairs of opposite cylinders converging in two V&#39;s (W-engine); or two horizontal, opposed rows (opposed, pancake, flat, or boxer engine). In each cylinder a piston slides up and down. One end of a connecting rod is attached to the bottom of the piston by a joint; the other and of the rod clamps around a bearing on one of the throws, or convolutions, of a crankshaft; the reciprocating (up-and-down) motions of the piston rotate the crankshaft, which is connected by suitable gearing to the drive wheels of the automobile. The number of crankshaft revolutions per minute is called the engine speed. The top of the cylinder is closed by a metal cover (called the head) bolted onto it. Into a threaded aperture in the head is screwed the spark plug, which provides ignition. 
         [0010]    A significant disadvantage present with the use of internal combustion engines that burn hydrocarbon fuel is the resulting pollution. In order to meet U.S. government restrictions on exhaust emissions, automobile manufacturers have had to make various modifications in the operation of their engines, primarily to reduce the emission of nitrogen oxides and other toxic substances. The pollution generated by conventional internal combustion engines has spurred the development of engines capable of delivering power while significantly reducing, or entirely eliminating, polluting emissions. 
         [0011]    U.S. Pat. No. 289,250, issued to Goyne discloses an operating valve for steam pumps wherein the piston is caused to flow forward and backward power strokes when the cylinder impacts piston L thereby moving slide valve C such that steam enters the opposite side of the piston. 
         [0012]    U.S. Pat. No. 371,636, issued to Snow, discloses a Steam Bell Ringer wherein a suspended bell is swung by the thrust of a piston of a single acting engine wherein the steam-inlet is closed and the exhaust passage opened early in the stroke. Snow discloses use of a “three-winged puppet valve,” referenced as “V” for controlling the admission of steam under the piston. The tail of valve “V” extends into the cylinder cavity so as to be struck by the piston in its decent thereby opening the valve. 
         [0013]    U.S. Pat. No. 384,095, issued to Snow, discloses a Steam Bell Ringer wherein further improvements are disclosed. Steam is admitted under piston “B” to drive same upward to the upper end of its stroke until its momentum is spent whereafter “gravity” will cause it to descend. 
         [0014]    U.S. Pat. No. 3,079,900, issued to Hunnicutt, discloses a fluid motor having an automatically operable servo valve that is directly responsive to pressure conditions and the position of the piston within the displacement chamber. A piston is resiliently biased toward one end of the cylinder by a compression spring. Compression spring functions to move the piston to its starting position where the face contacts an extending nose portion of poppet valve. Engagement of the poppet valve allows air to enter though conduit and throttle valve. 
         [0015]    U.S. Pat. No. 6,006,517, issued to Kownacki et al., discloses a fluid engine wherein a valve rod is movably housed to open a valve opening and close exhaust apertures during the piston&#39;s power stroke. 
         [0016]    U.S. Pat. No. 6,073,441, issued to Harju, discloses a pneumatic piston/cylinder apparatus which performs a single working stroke in one working direction, and is returned to its initial position without any external supply of compressed air by using a second compressed air channel to return the piston to its initial position. 
         [0017]    Many of the references in the background art rely on steam as the working fluid. The use of steam as a working fluid requires a steam generating apparatus, such as a boiler capable of producing high pressure steam. Use of a high pressure steam boiler, however, is considered undesirable due to complexity and the danger associated with high pressure steam. Furthermore, the high temperature associated with steam requires components capable of withstanding such temperatures further complicating the apparatus. Accordingly, there exists a need for a pneumatic reciprocating piston engine that uses a safe and reliable working fluid, other than steam. 
         [0018]    A further complication recognized with fluid motors has been the development of a reliable pneumatic reciprocating motor having simplified mechanics that provide reliable automatic cycling. The references in the art disclose overly complex valve and control structures that increase cost and degrade reliability. The references disclosed in the art simply fail to provide a reliable pneumatic reciprocating piston motor. Accordingly, there exists a need for an improved pneumatic reciprocating piston motor capable of powering a wide variety of devices. 
         [0019]    A further disadvantage with fluid motors of the background art involves the inability to run for a significant period of time on a single charge of pressurized fluid. Accordingly, there exists a need in the art for a rechargeable pneumatic engine capable of ramming for an extended period of time on a single charge. 
       BRIEF SUMMARY OF THE INVENTION 
       [0020]    The present invention overcomes the limitations and disadvantages present in the art by providing an improved pneumatic reciprocating piston engine that uses a mixture of compressed air and water as the working fluid with a combination of gravity and spring force functioning to return the piston after completion of the power stroke whereafter repeated power strokes may be achieved from a single charge of compressed fluid thereby providing a rechargeable pneumatic engine capable of running for an extended period of time on a single charge. 
         [0021]    A working fluid, preferably comprising a source of compressed air, is in fluid communication with the bottom portion of a generally vertically disposed cylinder via an inlet valve biased to a normally closed position. A piston is configured for reciprocating motion within the cylinder and traverses between bottommost and topmost positions. The piston is configured to engage the inlet valve when at the bottommost position thereby actuating the valve for a limited period of time to an open position so as to allow the introduction of compressed air and initiating of the power stroke to drive the piston upward. In a preferred embodiment, water is injected into the compressed air stream entering the cylinder to provide lubrication for the piston. The piston is driven upward by the working fluid until an uppermost stop is reached wherein the piston head has cleared a fluid exhaust port formed in the cylinder thereby allowing the working fluid to escape whereby the fluid travels through a closed loop circuit including a plurality of spaced check valves and a heat exchanger for absorbing heat from the surrounding environment ultimately directing pressurized fluid back into the cylinder inlet. A mass is connected to the piston, in overhead relation, by a spring connection. When the piston reaches the uppermost stop, momentum causes the spring connected mass to continue upward thereby placing the spring in compression and maintaining the piston above the exhaust port so as to allow escape of the working fluid therethrough. Return of the mass downward, caused both by gravity and spring energy, causes the mass to engage the piston and return the piston to its bottommost position whereby another stroke is initiated. Power output may be transferred to any suitable system. 
         [0022]    As the piston approaches top dead center, fluid is allowed to escape into a fluid return circuit via a cylinder exhaust port which incorporates a cheek valve to ensure one-way travel. The fluid return circuit includes, in the direction of flow, a pneumatic booster pump actuated by the return movement of the main piston to increase the pressure of the fluid. The booster cylinder output is in communication with the inlet of a heat exchanger that allows the expanding gas to absorb heat from the surrounding environment thereby providing beneficial cooling. The heat exchanger outlet is fluid communication with a remainder of the fluid return circuit including a plurality of spaced check valves that function to maintain pressure within the return circuit by preventing reverse flow. The fluid return circuit terminates at an inlet valve biased to a normally closed position. 
         [0023]    Accordingly, it is an object of the present invention to provide an improved pneumatic reciprocating piston engine that uses a mixture of compressed air and water as the working fluid with a combination of gravity and spring force functioning to return the piston after completion of the power stroke. 
         [0024]    Another object of the invention is to provide a rechargeable pneumatic engine capable of running for an extended period of time on a single charge. 
         [0025]    In accordance with these and other objects, which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0026]      FIG. 1  is a schematic illustration of a pneumatic reciprocating piston engine with the piston at bottom dead center; 
           [0027]      FIG. 2  is a schematic illustration showing the piston in mid-stroke; and 
           [0028]      FIG. 3  is a schematic illustration showing the piston at top dead center. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    With reference now to the drawings,  FIGS. 1-3  depict an improved pneumatic reciprocating piston engine, generally referenced as  10 , in accordance with the present invention. Pneumatic engine  10  is powered by a mixture of compressed air and water. A compressor  12  has an outlet  12   a  in fluid communication with a pressure vessel  14  via a compressed gas line  13 . Pressure vessel  14  includes a fan  11 , such as a squirrel cage type blower, that functions to increase pressure while thoroughly mixing the water and air. Pressure vessel  14  has an outlet  14   a  in fluid communication with a cylinder intake, generally referenced as  20 , via a compressed gas line  15  terminating in a valve  17 . Valve  17  comprises a normally closed valve. In a preferred embodiment, the compressed gas is air, however, the use of an alternate gas (such as Nitrogen) is considered within the scope of the present invention. A water source  16  is also in fluid communication with gas line  15  so as to provide a mixture of compressed air and water/water vapor to cylinder intake  20 . Injecting a relatively small amount of water, or other suitable liquid, into the compressed air supply has been found to unexpectedly increase the work extracted from the compressed air. In addition, the water functions as a lubricant for the reciprocating piston. 
         [0030]    Cylinder intake  20  is in fluid communication with a cylinder  30 . Intake  20  includes a check valve  22  having a movable element  22   a  that controls the flow of the compressed gas and water mixture into pneumatic engine  10 . As used herein, the term “check valve” shall broadly refer to any valve structure capable of actuation between open and closed positions, including biased valves intended to restrict flow to a single direction. Check valve  22  is maintained in a normally closed position by compressed air from the compressed air source. Check valve  22  is actuated from its normally closed position by forced downward movement of stem  22   b  that projects upward from intake  20  into cylinder  30 , and returns to the normally closed position as the piston moves upward. As more fully discussed below, actuation of check valve  22  is caused by engagement of a piston  40  as it returns to the bottom dead center position shown in  FIG. 1  Check valve  22  further functions to actuate valve  17  to an open position. More particularly, moveable element  22   a  of check valve  22  functions, upon opening by downward movement, to engage valve  17  thereby actuating it to an open configuration to allow for the introduction of pressurized fluid (e.g. air). 
         [0031]    Piston  40  includes peripheral seals  41 , and a connecting rod  42  fixed thereto that projects vertically upward therefrom. Connecting rod  42  preferably includes laterally extending reciprocating rigid members  44  that function to transmit power from piston  40  to any suitable external power receiving source via elongate, vertically disposed slotted apertures  32  defined in the cylinder wall. Cylinder  30  further includes at least one exhaust port  34  to allow at least a portion of the compressed air and water mixture to exit into a fluid return circuit as more fully discussed below when the piston  40  is at the top dead center position depicted in  FIG. 3 . Exhaust port  34  may be structured such that water may pool therein and subsequently back flow into the cylinder above the piston to provide a source of lubrication. A mass assembly  46  is connected to connecting rod  42  by a spring connection  48  whereby mass assembly  46  may separate from connecting rod  42 . More particularly as piston  40  travels upward, the top dead center position is reached when rigid members  44  reach the uppermost end of slotted apertures  32  formed in the cylinder wall thereby causing piston  40  to come to an abrupt stop. At the top dead center position, piston  40  has cleared exhaust port  34  sufficiently to allow for the escape of air thereby initiating the exhaust cycle. 
         [0032]    As best seen in  FIG. 3 , once piston  40  reaches top dead center, momentum causes mass assembly  46  to separate from connecting rod  42  and continue traveling upward compressing spring  48  and an optional upper spring  50 . Springs  48  and  40  function to dampen vibration resulting from piston  40  coming to an abrupt stop at top dead center. In addition, allowing mass assembly  46  to continue the momentum based upward travel functions to maintain piston  40  at the top dead center position for a period of time thereby allowing air to escape from cylinder  30  via exhaust port  34 . Ultimately springs  48  and  50  along with the influence of gravity cause mass assembly  46  to travel downward. Once mass assembly  46  engages connecting rod  42 , gravity functions to force piston  40  downward to bottom dead center wherein stem  22   b  of poppet valve  20  is automatically engaged thereby initiating the next power stroke. 
         [0033]    Power is transferred from pneumatic engine  10  via reciprocating motion of projecting members  44 . As should be apparent, work generated by engine  10  may be used to power any power consuming or receiving apparatus or system, including vehicles, generators, or any other suitable device. 
         [0034]    Exhaust port  34  is preferably in fluid communication with a fluid return circuit, generally referenced as  60  via a cylinder exhaust port which incorporates a check valve  62  to ensure one-way travel. Fluid return circuit  60  includes, a pneumatic booster primp  64  actuated by the return stroke of piston  40  to increase the pressure of the fluid downstream of booster pump  64 . Booster pump  64  has an outlet in fluid communication with the inlet of a heat exchanger  66  that allows the expanding gas to absorb heat from the surrounding environment thereby providing beneficial cooling. Heat exchanger  66  has an outlet in fluid communication with a check valve  67  and a second booster pump  68 , that is preferably actuated by an external source. Second booster pump  68  has an outlet in fluid communication with a heat exchanger  69  which functions to raise the temperature of the fluid within return circuit  60 . Heat exchanger  69  has an outlet in fluid communication with a pressure vessel  70  that provides an increased volume for containing pressurized fluid. Pressure vessel  70  includes a fan  71 , such as a squirrel cage type blower, that functions to increase pressure while thoroughly mixing the water and air. Pressure vessel  70  has an outlet in fluid communication with a series of check valves  72  whereafter the fluid return circuit includes a T-connection  74 . T-connection  74  includes a first outlet in fluid communication with a manually actuated valve  76  which in turn is in fluid communication with pressure vessel  14 . T-connection  74  further includes a second outlet in fluid communication with a fluid line  78  which terminates at a normally closed valve  79  having an outlet in fluid communication with cylinder intake  20 . Check valve  22  further functions to actuate valve  79  to an open position. More particularly, moveable element  22   a  of check valve  22  functions, upon opening by downward movement, to engage valve  79  thereby actuating it to an open configuration to allow for the introduction of pressurized fluid (e.g. air). 
         [0035]    The instant invention has been shown and described herein in what is considered to be the most practical and preferred embodiment. It is recognized, however, that departures may be made therefrom within the scope of the invention and that obvious modifications will occur to a person skilled in the art.