Patent Publication Number: US-6210131-B1

Title: Fluid intensifier having a double acting power chamber with interconnected signal rods

Description:
The United States Government has rights in this invention pursuant to Contract No. W-7405-ENG-48 between the United States Department of Energy and the University of California for the operation of Lawrence Livermore National Laboratory. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to fluid driven reciprocating apparatus, particularly to a fluid intensifier, and more particularly to a fluid driven reciprocating apparatus having a double acting power chamber with connected signal rods functioning as high pressure pistons or to transmit reciprocating mechanical power. 
     In industry, high pressure fluid, which includes air, water, and hydraulic fluid, has many application. For example, delivering fluid at a high pressure is often accomplished with an intensifier, which is a reciprocating fluid device having one or more large pistons connected to one or more small pistons. Intensifiers are powered by a low pressure fluid, such as compressed air or running water. Intensifiers can operate at any flow rate and still maintain their high pressure output, whereas this would be difficult to achieve with a high pressure pump driven by an electric motor, for example. 
     One common arrangement for an intensifier is one large double-acting low pressure power cylinder containing a piston which has a rod protruding from each face which are each connected to a small piston within a high pressure pumping cylinder. These prior art intensifiers generally have a single 4-way valve which switches both ends of the power chamber between intake and exhaust. The 4-way valve is controlled by one or two small pilot valves which are actuated by the main piston when it reaches either end of its stroke. These prior art intensifiers are relatively complicated. 
     One example of a market which can benefit from low cost intensifiers are homes having remote water supplies and no cheap source of electricity to pump water to the homes. If, for example, the homes are located on a hill and the water supply is running water in a stream bed at a lower elevation, intensifiers are commonly used to lift the water from the stream bed to a storage tank for the homes. In such instances, the intensifier is located at a lower elevation than the stream bed and is connected via a short pipe having its inlet located in the stream bed (e.g. to provide 10 meters of head water) which can pump water up the hill (e.g. 100 meters above the intensifier). Such commercial intensifiers are known in the art, as exemplified by the High Lifter Water Pump, Real Goods, 1991 Sourcebook, page 219, and U.S. Pat. No. 4,523,895 and U.S. Pat. No. 4,627,794. Other applications for fluid intensifiers include hydraulic and pneumatic applications, as well as for pressure amplifiers and booster pumps. 
     The present invention involves a fluid intensifier which is of a less complicated structure, and this in view of its simpler construction is lower in cost when compared to the existing commercial units. The present invention is a fluid driven reciprocating apparatus having a single double acting power chamber having a double acting piston which is connected to signal rods which also function as high pressure pistons or to transmit mechanical power. Optionally, only one rod may be used as a pump or power transmitter. When used as an intensifier the signal rods, which each include a pair of spaced seals or sealable members between which is located a vent, in addition to being high pressure pistons, provide a dual use as valve switching mechanisms, thereby replacing the conventionally used pilot valves. The double acting power chamber utilizes two separate intake-exhaust valves controlled by movement of the signal rods. The high pressure section of the apparatus includes two sets of inlet-outlet valves, and by the use of the vents controlled by the signal rods, the driving fluid and driven fluid can&#39;t mix. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an improved fluid intensifier. 
     A further object of the invention is to provide a fluid driven reciprocating apparatus having signal rods, that can function as a fluid intensifier or as a mechanical power transmitter. 
     A further object of the invention is to provide a double acting fluid driven apparatus having a double acting piston with connected signal rods which perform a switching function for intake-exhaust valves for the double acting piston, thereby eliminating separate pilot valves. 
     Another object of the invention is to provide a fluid driven reciprocating apparatus which includes a double acting piston controlled by a pair of intake-exhaust valves, and to which are connected a pair of signal rods which may function as high pressure fluid pistons and serve to control the intake-exhaust valves. 
     Another object of the invention is to provide a fluid intensifier or mechanical power transmitter which eliminates conventional 4-way valves and pilot valves, thus simplifying the construction and reducing the costs compared to conventional fluid intensifiers. 
     Other objects and advantages of the present invention will become apparent from the following description and accompanying drawings. The invention involves a fluid driven reciprocating apparatus having a double acting power chamber with connected opposed signal rods serving as high pressure pistons or for power transmission, and which eliminates the conventional pilot valves for the double acting power chamber. The dual use of the signal rods for valve switching and as high pressure pistons, for example, results in an intensifier which is simpler in construction and lower in cost compared to existing fluid intensifiers. The invention may use the opposite rods as signal rods, but use only of the rods as a pump or power rod. The double acting power chamber is controlled by a pair of intake-exhaust valves switched by the signal rods and thereby replaces the complex prior art 4-way valves. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings, which are incorporated into and form a part of the disclosure, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
     FIGS. 1,  2 , and  3  schematically illustrate in cross-section one-half cycle of oscillation of an embodiment of a fluid intensifier made in accordance with the present invention. 
     FIGS. 4,  5 ,  6  and  7  partially schematically illustrate in cross-section another embodiment of the double acting power chamber for the fluid intensifier with the intake-exhaust valves being in separate housings. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention involves a fluid driven reciprocating apparatus which can be utilized as a fluid intensifier or as a transmitter of mechanical power. The reciprocating apparatus can be driven by air, water, and hydraulic fluid, and includes a large double-acting piston located in a cylinder, and to which a pair of opposed rods are connected, and each rod provided with a pair of opposed spaced smaller piston-like members or seals which reciprocate in opposed cylinders which includes a vent located intermediate the piston-like members or seals. Movement of the large double-acting piston is controlled by a pair of intake-exhaust valve assemblies which are actuated by movement of said rods. For application as a fluid intensifier, each of the cylinders containing the rods also contain inlet-outlet valve assemblies. Thus, the opposed rods and piston-like members or seals function as high pressure pumps and as signal rods for the large double-acting piston. 
     The invention is described hereinafter and illustrated as a fluid intensifier, wherein the large double-acting piston is driven by low pressure fluid, such as a head of running water in a stream bed, and the opposed rods with the piston-like members or seals function as high pressure pistons to pump the running water to a point of use, such as a storage tank, for example. The fluid intensifier of the present invention achieves similar results as prior intensifiers, but with less complexity, greater performance advantages, and at lower costs due to the relative simplicity of construction. 
     The present invention, for example, utilizes two separate intake-exhaust valve assemblies to control the intake and exhaust of the large cylinder, rather than the previously used complex 4-way valves. This invention eliminates the need for the prior used pilot valves by making use of the spaced piston-like members or seals on the opposed rods to control the pair of intake-exhaust valve assemblies depending on piston position and the state of pressurization in each end of the power chamber containing the large double-acting piston. Note that because each rod has two piston-like members or seals along its length with a vented space in between, the driving fluid and driven fluid can&#39;t mix. The opposed rods perform a switching function to eliminate separate pilot valves. 
     Another difference between the present invention and the prior art fluid intensifiers is that the main (double-acting) piston doesn&#39;t impact any hard stop at the end of a stroke, which can be an advantage for high speed operation. In the prior art intensifiers the main piston typically impacts the pilot valves at each end of the double strokes, and makes subsequently hard stops when the pilot valves reach the end of their stroke. 
     An embodiment of the present invention is schematically illustrated in FIGS. 1-3, described in detail hereinafter, but only one-half cycle of oscillation which is sufficient to provide an understanding of the operation thereof. It is understood that the housing shown must be made of multiple pieces to permit manufacture and assembly, and such can be carried out by those skilled in the manufacturing art. Also, the seal or piston-like members located on the rods are provided with fluid seals such as o-rings to prevent leakage about the moving parts. Also, valve seats, which are well known in the art, could be included in the pair of intake-exhaust valve assemblies as an alternative to or to supplement the reciprocating seals or piston-like members therein. 
     FIGS. 1-3 illustrate the intake-exhaust valve assemblies as being integrated into the same housing as the large double-acting piston and the opposed rods. Alternately, these valve assemblies can each be located in a cylinder head of the power chamber (cylinder), or they can be located in separate housings, as illustrated in the embodiment of FIGS. 4-7. 
     Replacing the prior art 4-way valve, which is typically a spool valve with reciprocating seals, with separate intake-exhaust valves provides for a performance advantage because the separate valves of this invention have larger flow areas than similarly sized spool valves. Also, each valve in this invention can be located close to its cylinder head, located at opposite ends of the double-acting piston, so that long flow passageways from the cylinder head to the valve are eliminated. The resulting reductions in pressure losses in the driving fluid is an advantage when the driving fluid is viscous (e.g. water), or when high speed operation is desired. Thus, the present invention can provide a higher output for a given intensifier size. 
     If in utilizing the present invention, there is an exhaust restriction causing the exhausting side of the power chamber to be pressurized to a large fraction of the driving pressure, such could inadvertently shut the intake valve on the driving side, depending on the area ratio of the ends of the moving valve part, and thus any exhaust restriction should be avoided. Further, exhaust restrictions are normally avoided since power would be wasted in pumping the exhaust out of the chamber. 
     Referring now to the drawings, FIGS. 1-3 illustrate in cross-section an embodiment of the present invention configured as a fluid intensifier, and as pointed out above only show one-half cycle of oscillation. As shown in FIGS. 1-3, the fluid intensifier is mounted in a single housing generally indicated at  10  in which located a power chamber or cylinder  11 , a pair of intake-exhaust valve chambers  12  and  13 , and pair of high pressure chambers or cylinders  14  and  15 , and a pair of fluid inlet-outlet valve chambers  16  and  17 . Reciprocally mounted in power chamber  11  is a double acting piston  18  having signal rods  19  and  20  connected thereto and which extend into high pressure cylinders  14  and  15 , and on each are mounted a pair of spaced members or pistons  21 - 22  and  23 - 24 . The housing  10  includes a pair of power fluid supply or intake ports  25  and  26  connected to valve chambers  12  and  13 , and a pair of power fluid exhaust ports  27  and  28 , also connected to valve chambers  12  and  13 . In addition, housing  10  is provided with two pair of fluid passageways  29 - 30  and  31 - 32 , with passageways  29  and  31  interconnecting valve chambers  12  and  13  with power chamber or cylinder  11 , but on opposite sides of piston  18 , and passageways  30  and  32  interconnecting valve chambers  12  and  13  with high pressure chambers or cylinders  14  and  15 . Housing  10  additionally includes a pair of signal vent ports  33  and  34  in high pressure cylinders  14  and  15  located intermediate respective pistons or members  21 - 22  and  23 - 24 . The pair of fluid inlet-outlet valve chambers  16  and  17  are in open communication with ends of high pressure cylinders  14  and  15 , and each include an inlet port  35 - 36  for fluid to be pumped and an outlet port  37 - 38  for pumped fluid. Reciprocally mounted in each of valve chambers  12  and  13  is a valve member  39 - 40 , each having a pair of pistons or members  41 - 42  and  43 - 44  interconnected by stems or rods  45 - 46 , which move in different diameter sections  47 - 48  and  49 - 50  forming the valve chambers  12  and  13 . Power fluid supply or intake ports  25  and  26  and fluid passageways  29  and  31  are connected to the smaller diameter sections  47  and  49 ; while power fluid exhausts ports  27  and  28  and fluid passageways  30  and  32  are connected to the larger diameter sections  48  and  50  of valve chambers  12  and  13 . Fluid inlet outlet valve chambers  16  and  17  are provided with check or ball valve or members  51 - 52  and  53 - 54 , which cooperate with respective seats  55 - 56  and  57 - 58 , and function as known in the art. 
     In the example set forth above, the intake ports  35  and  36  of valve chambers  16  and  17  are connected to a supply of water to be pumped, such as a stream, lake, etc., and the outlet ports  37  and  38  of valve chambers  16  and  17  are connected to a point of use or to a storage tank, etc. Similarly, power fluid supply or intake ports  25  and  26  are connected to the same water supply as intake ports  35  and  36  of valve chambers  16  and  17 , but power fluid exhaust ports  27  and  28 , which must be at a lower pressure, may or may not be connected to the same point of use or storage tank as are outlet ports  37  and  38  of valve chambers  16  and  17 . The exhaust must be at a low pressure, e.g., ambient or located further downstream or below lake level, for example. Also, while not shown, it is to be understood that the piston  18  in power chamber or cylinder  11 , pistons or members  21 - 22  and  23 - 34  in high pressure chambers or cylinders  14  and  15 , and the pistons or members  41 - 42  and  43 - 44  of valve members  39 - 40  in valve chambers  12  and  13 , are each provided with an appropriate fluid seal, such as one or more o-rings, to prevent leakage of fluid therepast as these members or pistons move in their respective cylinders or chambers. Also, the valve seats  55 - 56  and  57 - 58  of valve chambers  16  and  17  may be formed of a different material, not shown, than the material of housing  10 . 
     In operation, as shown in FIG. 1, power fluid via supply or intake port  25  enters valve chamber section  47  moving valve member  39  to the right, whereby the fluid enters passageway  29 , chamber  11 , an inner portion of cylinder  14 , passageway  32  and into valve chamber section  50  moving valve member  40  to the right, whereby power fluid supply port  26  is blocked. As shown exhaust port  28  is open thereby venting passageway  31 . Passageway  30  and an inner portion of cylinder  15  is vented via signal vent port  34 , and an outer portion of cylinder  14  is vented via signal vent port  33 , whereby piston  18  is moved to the right as shown by arrow  59  causing rods  19  and  20 , along with their spaced pistons or members  21 - 22  and  23 - 24 , to move to the right to the position shown in FIG. 2, wherein the power fluid supply is now only in valve chamber section  47 , passageway  29  and in chamber or cylinder on the left side of piston  18  which has been moved to the right in cylinder  11 . As piston  18  and rods  19 - 20  travel to the right, fluid to be pumped enters valve chamber  16  and is discharged from valve chamber  17 , to a point of use, as indicated by the valve members  51  and  54  being raised from their seats  55  and  58 , and as shown in FIG. 2, at the end of the stoke of piston  18  and rods  19 - 20 , valve members  51  and  54  are again seated. Near the end of the stroke of piston  18  as shown in FIG. 2, member  22  has moved so that passageway  32  and chamber section  50  vent through port  33 . With chamber section  50  vented the pressure of the power fluid in supply or intake port  26  in valve chamber  13  is sufficient to move the valve member  40  to the left as shown in FIG. 2, and as valve member  40  is moved further to the left, as shown in FIG. 3, it allows valve chamber section  49  to be connected to passageway  31  whereby the power fluid enters cylinder  11  at the right of piston  18 , and passes into an inner portion of cylinder  15 , through passageway  30  to valve chamber section  48  causing valve member  39  to move to the left blocking fluid passage from valve chamber  47  to passageway  29 , see FIG. 3, due to the greater cross-sectional area on the face of valve member  42  compared to the cross-sectional area on the face of value member  41 . While not shown in FIG. 3, valve member  39  continues its leftward movement to vent the left side of the power cylinder  11  out through passageway  29  and port  27 . As the power fluid continues to fill the right side of power chamber  11  the piston  18  and connected rods  19  and  20  are moved to the left initiating a return stroke. As the return stroke begins, the state of the apparatus is opposite to that shown in FIG. 1, with precise symmetry. The return stroke causes the pump chamber  17  to fill and the pump chamber  16  to discharge to a point of use. Near the end of the return stroke of piston  18  (to the left), passageway  30  is vented through port  34  so that power fluid again enters supply or intake port  25  of valve chamber  12  and the sequence of FIGS. 1,  2  and  3  are repeated. 
     The embodiment of FIGS. 4-7, which omits the fluid pumping chamber  16  and  17 , and the outer pistons or members  21  and  24  of the FIGS. 1-3 embodiment, illustrate an embodiment, similar to that of FIGS. 1-3, but designed to produce or transmit mechanical power rather than for intensifying the flow of fluid as in the FIGS. 1-3 embodiment. Also, the intake/exhaust valves in FIGS. 4-7 are located in separate housings from the power chamber housing. As shown in FIGS. 4-7 the fluid driven reciprocating apparatus generally indicated at  60  basically comprises a piston housing  61  and a pair of intake/exhaust valve housings  62  and  63 . Located in housing  61  are three cylinder sections  64 ,  65  and  66  in which are located pistons  67 ,  68  an  69 , with pistons  68  and  69  connected to piston  67  via rods  70  and  71 . Housing  61  is provided with four ports or openings  72 ,  73 ,  74  and  75 , with ports  72  and  74  being located in cylinder section  64 , port  73  located in cylinder section  65 , and port  75  located in cylinder section  66 . Intake/exhaust valve housings  62  and  63  have chamber sections  76 - 77  and  78 - 79  with chamber sections  77  and  79  being larger in diameter than chamber sections  76  and  78 . Valve chamber sections  76  and  78  includes ports  80 - 81  and  82 - 83 , while valve chamber sections  77  and  79  includes ports  84 - 85  and  86 - 87 . Ports  80  and  82  are connected to supply lines  88  and  89 , which are connected to a fluid source indicated at  90 . Port  81  is connected by line  91  to port  72  of housing  61 , port  84  being connected to port  75  in housing  61  by a line  92 , port  83  being connected by line  93  to port  74  of housing  61 , port  86  being connected to port  73  of housing  61  via a line  94 , with ports  85  and  87  open to atmosphere, for example. 
     As shown in FIG. 4, with intake port  80  open and the exhaust port  87  open, fluid under pressure from fluid source  90  passes through line  88 , port  80  and into valve chamber section  76  moving a valve member  95  to the right, and then through port  81 , line  91 , port  72 , chamber section  64 , an inner portion of chamber section  65 , port  73 , line  94 , port  86 , and into valve chamber section  79  moving a valve member  96  to the right thereby closing the port  82  connected to line  89 . Valve members  95  and  96  have pistons or members  97 - 98  and  99 - 100  interconnected by stems  101  and  102 , with pistons  98  and  100  having a larger cross-sectional area than pistons  97  and  99 , whereby the valve members  95  and  96  are moved to the location shown in FIG. 4 due to the differential in pressure thereacross. As shown in FIG. 4, entry of pressurized fluid into cylinder section  64  causes piston  67  and connected pistons  68  and  69  to move to the right as indicated by arrow  103 . 
     Piston  67  continues to move to the right as indicated by arrow  104  in FIG. 5 to a switching position when piston  67  nears the end of its rightward stroke in chamber section  64  of housing  61 . At the switching point, as shown in FIG. 5, piston or member  68  has moved past port  73 , whereby the fluid pressure is exhausted from valve chamber section  79 , and the fluid pressure in line  89  via port  82  acts against valve piston  99  causing it to move to the left, as seen in FIG. 5, whereby the fluid pressure is only in valve chamber section  76 , line  91  and housing cylinder section  64 , as shown. Further movement of valve  96  to the left initiates a switching action which causes fluid from source  90  to enter line  93 , the cylinder section  64  at the right of piston  67 , and inner section of cylinder section  66 , line  92  and into valve chamber section  77  cause valve member  95  to move to the left as shown in FIG. 6, wherein the valve member  95  is in a switching mode and valve member  96  has its intake open. As the valve member  95  continues to move to the left, the fluid under pressure into valve chamber section  76  is blocked as shown in FIG.  6 . Continued movement to the left of valve member  95  causes valve piston  97  to uncover port  81 , whereby fluid on the left side of the piston  67  is exhausted via chamber section  76 , chamber section  77  and exhaust port  85 , as shown in FIG. 7, whereby the piston  67  and connected pistons  68  and  69  move to the left as shown by arrow  105  in FIG. 7, and thus valve member  95  is in an exhaust open mode and valve member  96  is in an intake open mode, which will continue until piston  67  nears the end of its leftward stroke and the valve  95  and  96  initiate a switching action to reverse the movements of the pistons. It is understood that as pistons or members  68  and  69  move in either direction they transmit mechanical energy, such as may be used to drive a reciprocating device, such as a saw blade fluid motor. Also, as pointed out above, the pistons and valve pistons are provided with fluid seals, such as o-rings to prevent leakage of fluid therepast. 
     It has thus been shown that the present invention provides a simply constructed reciprocating fluid drive mechanism, which can be utilized as a fluid intensifier or as a mechanical energy transmitting device. The mechanism of this invention eliminates the need for complicated 4-way valve assemblies, as well as eliminating pilot valves for controlling movement piston direction. The invention can be used as a reciprocating air motor or as a hydraulic motor (oil or water), but is ideally suited to be used as a fluid pressure intensifier. For example, by using 100 psi air to drive the mechanism, the mechanism can deliver hydraulic fluid at 1000 psi; or it can be used for lifting water from a stream up to a house or storage tank located on a hill, by merely using the power of the water itself. 
     While particular embodiment of the invention have been illustrated and described to exemplify and teach the principles of the invention, such are not intended to be limiting. Modifications and changes may become apparent to those skilled in the art, and it is intended that the invention be limited only by the scope of the appended claims.