초록 ▼

The disclosed invention introduces an efficient lifting mechanism for reciprocating vertically a load system, the load consisting of the aggregate weights of a cargo payload in conjunction with “dead weights” of moving parts of the lifting apparatus. The disclosed invention uses a hydro-pneumatic li

The disclosed invention introduces an efficient lifting mechanism for reciprocating vertically a load system, the load consisting of the aggregate weights of a cargo payload in conjunction with “dead weights” of moving parts of the lifting apparatus. The disclosed invention uses a hydro-pneumatic linear actuator to lift the load and a pressurized accumulator, acting as a force intensifier. The pressurized accumulator, acting as a self-contained stored energy source, provides to the actuator adequate power to lift the “dead weights” plus part of the cargo payload. An external power source provides to the actuator adequate power to lift the remainder of the cargo payload. The disclosed invention saves significant amounts of power and energy in applications in which the “dead weights” are sizable compared to the cargo load. The disclosed invention provides also exceptional means for accurate motion control of the cargo payload.

대표청구항 ▼

1. A hydro pneumatic counterweighted lifting system for elevating vertically cargo loads, comprising: a hydro-pneumatic, double-acting, triple-chamber actuator using hydraulic fluid and gas to reciprocate a load;said actuator mounted vertically on a structural base;said actuator comprising:an outer

1. A hydro pneumatic counterweighted lifting system for elevating vertically cargo loads, comprising: a hydro-pneumatic, double-acting, triple-chamber actuator using hydraulic fluid and gas to reciprocate a load;said actuator mounted vertically on a structural base;said actuator comprising:an outer cylinder vertically mounted on said structural base;an outer piston reciprocating inside the bore of said outer cylinder, said outer piston comprising a piston rod and a piston head, said piston head reciprocating inside the bore of said outer cylinder, said piston rod reciprocating in and out of the top end of said outer cylinder, said outer piston reciprocating said load as said piston rod reciprocates in and out of said outer cylinder;an inner cylinder affixed to the structural base of said actuator and concentric with said outer cylinder;an inner piston affixed at its upper end to the top of said outer piston and concentric with said outer piston, said inner piston comprising at its other end a piston head, said piston head comprising a first face surface, said inner piston reciprocating inside a bore of said inner cylinder;a cylinder head affixed to the upper end of said outer cylinder, said piston rod sliding in a bore of said cylinder head;wherein said structural base comprises an end cap attached to the bottom of said outer cylinder;said actuator further comprising three functional chambers, said chambers comprising:a first hydraulic chamber enclosed inside the bore of said inner cylinder beneath said inner piston first face surface, said first chamber having a hydraulic UP port connecting said first chamber to a first utility port of a hydraulic pump, said first chamber, when hydraulically pressurized, forcing said actuator to extend up by applying pressure on said first face surface of said inner piston;said first chamber having a circular shaped effective hydraulic area determined by the bore diameter of said inner cylinder, said first chamber effective area sized to provide, at full operating hydraulic pressure, an upward force equal to about half the difference between the maximum cargo load up and the minimum cargo load down;a second hydraulic chamber contained between the bore diameter of said outer cylinder and the outer diameter of said outer piston rod, said second chamber comprising a hydraulic DOWN port connecting said second chamber to a second utility port of said hydraulic pump, said second chamber, when hydraulically pressurized, forcing said actuator to retract down by applying hydraulic pressure on said outer piston;said second chamber having an annular shape hydraulic effective area, said annular shape contained between the bore diameter of said outer cylinder and the outer diameter of said outer piston rod, said second chamber effective area sized to provide, at full operating hydraulic pressure, a downward force equal to about half the difference between the maximum cargo load up and the minimum cargo load down;a third counterweight chamber contained between the bore diameter of said outer cylinder and the bore diameter of said inner cylinder, said third counterweight chamber comprising a counterweight port connecting said third counterweight chamber to at least one pressure vessel, said third counterweight chamber constantly charged with pressurized gas, providing a consistent extension force up;said third counterweight chamber having an annular shaped effective area, said annular shaped effective area contained between the bore diameter of said outer cylinder and the bore diameter of said inner cylinder, said third chamber effective area sized to provide said consistent extension force up, said force about equal to the cumulative weight of the unloaded moving parts of the lifting system plus half the difference between the maximum cargo load up and the minimum cargo load down, said force calculated at the minimum operating pressure in said third chamber;said actuator further comprising sealing means to prevent leakage of the hydraulic fluids or the pressurized gas out of said chambers;said actuator designed to automatically circulate the hydraulic fluid in and out of said hydraulic chambers during normal operation in order to bleed entrapped air, said automatic bleeding accomplished by contracting to minimum the volume of hydraulic fluid in each hydraulic chamber during the course of every duty cycle;said first hydraulic chamber decreasing its volume as said inner piston is sliding down into said inner cylinder during downstroke retraction, flushing out all hydraulic fluid and any entrapped air contained in said first hydraulic chamber, except for a small percentage, into the hydraulic system, thereby bleeding out any entrapped air from said first hydraulic chamber during every duty cycle; andsaid second hydraulic chamber decreasing its volume as said outer piston is sliding up in said outer cylinder during upstroke extension, flushing out all hydraulic fluid and any entrapped air contained in said second hydraulic chamber, except for a small percentage, into the hydraulic system, thereby bleeding out any entrapped air from said second hydraulic chamber during every duty cycle. 2. A lifting system in accordance with claim 1, wherein said at least one pressure vessel comprises a plurality of vessels containing said pressurized gas; said pressure vessels' internal volumes interconnected to each other via a plurality of conduits, said pressure vessels internal volumes connected to said third counterweight chamber of said actuator via at least one conduit;said pressure vessels charged with said pressurized gas, said pressurized gas set to apply said consistent extension force up to said outer piston, said force equal to about the cumulative weight of the unloaded moving parts of the lifting system plus half the difference between the maximum cargo load up and the minimum cargo load down, said force calculated at the minimum operating pressure in said third counterweight chamber;said internal volumes of pressurized gas in said pressure vessels and said actuator adding up to a total volume no smaller than ten times the volume of pressurized gas displaced by said actuator during one stroke, said displaced volume equal to said effective area of said third chamber multiplied by the length of a full stroke of said actuator. 3. A lifting system in accordance with claim 2, wherein said hydraulic pump is part of a power train providing hydraulic flow to reciprocate said actuator; said hydraulic pump comprises:a variable displacement closed-circuit hydraulic pump, said pump displacing a variably controlled volume of hydraulic fluid per turn of the pump;said hydraulic pump coupled to a drive comprising an electric motor, said electric motor powered by grid power or by an auxiliary generator, said drive transferring output torque at constant speed to an input shaft of said hydraulic pump;said first and second utility ports of said hydraulic pump connected via hydraulic conduits to said hydraulic UP and DOWN ports of said actuator respectively;said hydraulic pump, when commanded UP, causing hydraulic fluid to flow through said first utility port into said first hydraulic chamber, thereby causing said outer piston to move in the UP direction;said hydraulic pump, when commanded DOWN, causing hydraulic fluid to flow through said second utility port into second hydraulic chamber, thereby causing said outer piston to move in the DOWN direction. 4. A lifting system in accordance with claim 2, wherein said hydraulic pump is part of a power train providing hydraulic flow to reciprocate said actuator; said hydraulic pump comprises:a variable displacement closed-circuit hydraulic pump, said pump displacing a variably controlled volume of hydraulic fluid per turn of the pump;said hydraulic pump coupled to a drive comprising a combustion engine, said drive transferring output torque at constant speed to an input shaft of said hydraulic pump;said first and second utility ports of said hydraulic pump connected via hydraulic conduits to said hydraulic UP and DOWN ports of said actuator respectively;said hydraulic pump, when commanded UP, causing hydraulic fluid to flow through said first utility port into said first hydraulic chamber, thereby causing said outer piston to move in the UP direction;said hydraulic pump, when commanded DOWN, causing hydraulic fluid to flow through said second utility port into said second hydraulic chamber, thereby causing said outer piston to move in the DOWN direction. 5. A lifting system in accordance with claim 2, wherein said hydraulic pump is part of a power train providing hydraulic flow to reciprocate said actuator; said hydraulic pump comprises:a fixed displacement closed-circuit hydraulic pump, displacing a fixed volume of hydraulic fluid per turn of the pump;said hydraulic pump coupled to an electric motor, said electric motor powered by grid power or by an auxiliary generator, said motor transferring output torque to an input shaft of said hydraulic, the direction of rotation and speed of said electric motor controlled by a variable speed drive, said variable speed drive controlling the voltage and frequency of AC power to said electric motor, thereby controlling the direction and speed of rotation of said motor and said coupled hydraulic pump;said first and second utility ports of said hydraulic pump connected via hydraulic conduits to said hydraulic UP and DOWN ports of said actuator respectively;said hydraulic pump, when commanded UP, spinning in one direction, causing hydraulic fluid to flow through said first utility port into the first hydraulic chamber, thereby causing said outer piston to move in the UP direction;said hydraulic pump, when commanded DOWN, spinning in the opposite direction, causing hydraulic fluid to flow through said second utility port into the second hydraulic chamber, thereby causing said outer piston to move in the DOWN direction. 6. A lifting system in accordance with claim 3, 4 or 5, further comprising a control system; said control system comprising monitoring devices, including at least one position sensor monitoring continuously the stroke of said actuator, a plurality of pressure sensors monitoring continuously pressures in each of said chambers of said actuator and a plurality of flow and pressure control valves;said monitoring devices supplying data to a programmable logic controller (PLC);said data processed and acted upon by algorithms by the PLC, providing motion commands to said lifting system;said control system controlling motion parameters of the lifting system, including position, direction, velocity, start-stop, acceleration and deceleration by controlling the hydraulic flow to said actuator;said control system changing said motion parameters in real time by adjusting hydraulic flow to said actuator on both upstroke and downstroke. 7. The lifting system in accordance with claim 1, further comprising cushioning means to avoid impact loads when said outer piston comes to stop at its up and down end strokes, said cushioning means slowing down the velocity of said outer piston as it approaches end stroke by metering hydraulic fluid through said hydraulic UP and DOWN ports; said means for downstroke cushioning comprising a dome shaped pin mounted onto said first face of said inner piston and a first cylindrical cavity in said end cap, said first cavity connected to said hydraulic UP port of said first chamber, said first cavity having a slightly bigger diameter than said pin, said pin forming a first annular orifice between said pin and said first cavity when entering said first cavity, thus forcing hydraulic fluid in said first hydraulic chamber to flow out through said first annular orifice, thereby slowing down said outer piston;said pin having a variable longitudinal profile, said first annular orifice cross section area decreasing as said pin moves into said first cavity, said profile shaped to provide a desired deceleration of said outer piston;said means for downstroke cushioning further comprising a first check valve between said hydraulic UP port and said first hydraulic chamber, said valve enabling one way flow from said hydraulic UP port to said first hydraulic chamber and blocking flow in the opposite direction, thus enabling unrestricted hydraulic flow into said first hydraulic chamber on upstroke;said means for upstroke cushioning comprising a sleeve mounted onto said outer piston rod adjacent to said outer piston head and a second cylindrical cavity in said cylinder head, said second cavity connected to said hydraulic DOWN port of said second hydraulic chamber, said second cavity having a slightly bigger diameter than said sleeve, said sleeve forming a second annular orifice between said sleeve and said second cavity when entering said second cavity, thus forcing hydraulic fluid in said second hydraulic chamber to flow out through said second annular orifice, thereby slowing down said outer piston;said sleeve having a variable longitudinal profile, said second annular orifice cross section area decreasing as said sleeve moves into said second cavity, said profile shaped to provide a desired deceleration of said outer piston;said means for upstroke cushioning further comprising a second check valve between said hydraulic DOWN port and said second hydraulic chamber, said valve enabling one way flow from said hydraulic DOWN port to said second hydraulic chamber and blocking flow in the opposite direction, thus enabling unrestricted hydraulic flow into said second hydraulic chamber on downstroke. 8. The lifting system in accordance with claim 1, further comprising: at least one pulley affixed to the top of said outer piston;at least one cable wrapped around the top of said pulley, one end of each said cable anchored to a stationary point, the lifted loads suspended from the other end of each of said cable; andsaid load reciprocating freely as said outer piston moves up and down, said load reciprocating at twice the speed and stroke of the outer piston. 9. The lifting system in accordance with claim 1, further comprising: at least one gear wheel affixed to the top of said outer piston;at least one chain wrapped around the top of said gear wheel, one end of each said chain anchored to a stationary point, the lifted loads suspended from the other end of each of said chain; andsaid load reciprocating freely as outer piston moves up and down, said load reciprocating at twice the speed and stroke of the outer piston. 10. The lifting system in accordance with claim 1, further comprising: at least one sheave affixed to the top of said outer piston;at least one belt wrapped around the top of said sheave, one end of each said belt anchored to a stationary point, the lifted loads suspended from the other end of each of said belt; andsaid load reciprocating freely as outer piston moves up and down, said load reciprocating at twice the speed and stroke of the outer piston. 11. A rod-lifting system for extraction of fluids from subsurface formations, including a subsurface downhole pump immersed in a casing tube and connected via a rod string to a surface-mounted lifting system, said lifting system reciprocating the downhole pump up and down, lifting a column of fluid and gas mixture in every stroking cycle; said lifting system comprising:a hydro-pneumatic, double-acting, triple-chamber actuator using hydraulic fluid and gas to reciprocate a load;said actuator mounted vertically on a structural base;said actuator comprising:an outer cylinder vertically mounted on said structural base;an outer piston reciprocating inside the bore of said outer cylinder, said outer piston comprising a piston rod and a piston head, said piston head reciprocating inside the bore of said outer cylinder, said piston rod reciprocating in and out of the top end of said outer cylinder, said outer piston reciprocating said load as said piston rod reciprocates in and out of said outer cylinder;an inner cylinder affixed to the structural base of said actuator and concentric with said outer cylinder;an inner piston affixed at its upper end to the top of said outer piston and concentric with said outer piston, said inner piston comprising at its other end a piston head, said piston head comprising a first face surface, said inner piston reciprocating inside a bore of said inner cylinder;a cylinder head affixed to the upper end of said outer cylinder, said piston rod sliding in a bore of said cylinder head;wherein said structural base comprises an end cap attached to the bottom of said outer cylinder;said actuator further comprising three functional chambers, said chambers comprising:a first hydraulic chamber enclosed inside the bore of said inner cylinder beneath said inner piston first face surface, said first chamber having a hydraulic UP port connecting said first chamber to a first utility port of a hydraulic pump, said first chamber, when hydraulically pressurized, forcing said actuator to extend up by applying pressure on said first face surface of said inner piston;said first chamber having a circular shaped effective hydraulic area determined by the bore diameter of said inner cylinder, said first chamber effective area sized to provide, at full operating hydraulic pressure, an upward force equal to about half the weight of the fluid column in the well casing tube;a second hydraulic chamber contained between the bore diameter of said outer cylinder and the outer diameter of said outer piston rod, said second chamber comprising a hydraulic DOWN port connecting said second chamber to second utility port of said hydraulic pump, said second chamber, when hydraulically pressurized, forcing said actuator to retract down by applying hydraulic pressure on said outer piston;said second chamber having an annular shape hydraulic effective area, said annular shape contained between the bore diameter of said outer cylinder and the outer diameter of said outer piston rod, said second chamber effective area sized to provide, at full operating hydraulic pressure, a downward force equal to about half the weight of the fluid column in the well casing tube;a third counterweight chamber contained between the bore diameter of said outer cylinder and the bore diameter of said inner cylinder, said third counterweight chamber comprising a counterweight port connecting said third counterweight chamber to at least one pressure vessel, said third counterweight chamber constantly charged with pressurized gas, providing a consistent extension force up;said counterweight third chamber having an annular shaped effective area, said annular shaped effective area contained between the bore diameter of said outer cylinder and the bore diameter of said inner cylinder, said third chamber effective area sized to provide an upward force, said force about equal to the cumulative weight of the unloaded moving parts of the lifting system, rod string and downhole pump, plus half the weight of the fluid column in the well casing tube, said force calculated at the minimum operating pressure in said third chamber;said actuator further comprising sealing means to prevent leakage of the hydraulic fluids or the pressurized gas out of said chambers;said actuator designed to automatically circulate the hydraulic fluid in and out of said hydraulic chambers during normal operation, in order to bleed entrapped air, said automatic bleeding accomplished by contracting to minimum the volume of hydraulic fluid in each hydraulic chamber during the course of every duty cycle;said first hydraulic chamber decreasing its volume as said inner piston is sliding down into said inner cylinder during downstroke retraction, flushing out all hydraulic fluid and any entrapped air contained in said first hydraulic chamber, except for a small percentage, into the hydraulic system, thereby bleeding out any entrapped air from said first hydraulic chamber during every duty cycle; andsaid second hydraulic chamber decreasing its volume as said outer piston is sliding up in said outer cylinder during upstroke extension, flushing out all hydraulic fluid and any entrapped air contained in said second hydraulic chamber, except for a small percentage, into the hydraulic system, thereby bleeding out any entrapped air from said second hydraulic chamber during every duty cycle. 12. A lifting system in accordance with claim 11, wherein said at least one pressure vessel comprises a plurality of vessels containing said pressurized gas; said pressure vessels' internal volumes interconnected to each other via a plurality of conduits, said pressure vessels' internal volumes connected to said third counterweight chamber of said actuator via at least one conduit;said pressure vessels charged with said pressurized gas, said pressurized gas set to apply-a said consistent extension force up to said outer piston, said force equal to about the cumulative weight of the unloaded moving parts of the lifting system, rod string and downhole pump, plus half the weight of the fluid column in the well casing tube, said force calculated at the minimum operating pressure in said third counterweight chamber;said internal volumes of pressurized gas in said pressure vessels and said actuator adding up to a total volume no smaller than ten times the volume of pressurized gas displaced by said actuator during one stroke, said displaced volume equal to said effective area of said third chamber multiplied by the length of a full stroke of said actuator. 13. A lifting system in accordance with claim 12, wherein said hydraulic pump is part of a power train providing hydraulic flow to reciprocate said actuator; said hydraulic pump comprises:a variable displacement closed-circuit hydraulic pump, said pump displacing a variably controlled volume of hydraulic fluid per turn of the pump;said hydraulic pump coupled to a drive comprising an electric motor, said electric motor powered by grid power or by an auxiliary generator, said drive transferring output torque at constant speed to an input shaft of said hydraulic pump;said first and second utility ports of said hydraulic pump connected via hydraulic conduits to said hydraulic UP and DOWN ports of said actuator respectively;said hydraulic pump, when commanded UP, causing hydraulic fluid to flow through said first utility port into said first hydraulic chamber, thereby causing said outer piston to move in the UP direction;said hydraulic pump, when commanded DOWN, causing hydraulic fluid to flow through said second utility port into said second hydraulic chamber, thereby causing said outer piston to move in the DOWN direction. 14. A lifting system in accordance with claim 12, wherein said hydraulic pump is part of a power train, providing hydraulic flow to reciprocate said actuator; said hydraulic pump comprises:a variable displacement closed-circuit hydraulic pump, said pump displacing a variably controlled volume of hydraulic fluid per turn of the pump;said hydraulic pump coupled to a drive comprising a combustion engine, said drive transferring output torque at constant speed to an input shaft of said hydraulic pump;said first and second utility ports of said hydraulic pump connected via hydraulic conduits to said hydraulic UP and DOWN ports of said actuator respectively;said hydraulic pump, when commanded UP, causing hydraulic fluid to flow through said first utility port into said first hydraulic chamber, thereby causing said outer piston to move in the UP direction;said hydraulic pump, when commanded DOWN, causing hydraulic fluid to flow through said second utility port into said second hydraulic chamber, thereby causing said outer piston to move in the DOWN direction. 15. A lifting system in accordance with claim 12, wherein said hydraulic pump is part of a power train, providing hydraulic flow to reciprocate said actuator; said hydraulic pump comprises:a fixed displacement closed-circuit hydraulic pump, displacing a fixed volume of hydraulic fluid per turn of the pump;said hydraulic pump coupled to an electric motor, said electric motor powered by grid power or by an auxiliary generator, said motor transferring output torque to an input shaft of said hydraulic pump, the direction of rotation and speed of said electric motor controlled by a variable speed drive, said variable speed drive controlling the voltage and frequency of AC power to said electric motor, thereby controlling the direction and speed of rotation of said motor and said coupled hydraulic pump;said first and second utility ports of said hydraulic pump connected via hydraulic conduits to hydraulic UP and DOWN ports of said actuator respectively;said hydraulic pump, when commanded UP, spinning in one direction, causing hydraulic fluid to flow through said first utility port into said first hydraulic chamber, thereby causing said outer piston to move in the UP direction;said hydraulic pump, when commanded DOWN, spinning in the opposite direction, causing hydraulic fluid to flow through said second utility port into said second hydraulic chamber, thereby causing the actuator piston to move in the DOWN direction. 16. A lifting system in accordance with claim 13, 14 or 15, further comprising a control system; said control system comprising monitoring devices, including at least one position sensor monitoring continuously the stroke of said actuator, a plurality of pressure sensors monitoring continuously pressures in each of said chambers of said actuator and a plurality of flow and pressure control valves;said control system comprising monitoring devices collecting well and downhole data;said monitoring devices supplying data to a programmable logic controller (PLC);said data processed and acted upon by algorithms by said PLC, providing motion commands to said lifting system;said control system controlling motion parameters of the lifting system, including position, direction, velocity, start-stop, acceleration and deceleration by controlling the hydraulic flow to said actuator;said control system changing motion parameters in real time by adjusting hydraulic flow to said actuator on both upstroke and downstroke. 17. The lifting system in accordance with claim 11, further comprising cushioning means to avoid impact loads when said outer piston comes to stop at its up and down end strokes, said cushioning means slowing down the velocity of said outer piston as it approaches end stroke by metering hydraulic fluid through said hydraulic UP and DOWN ports; said means for downstroke cushioning comprising a dome shaped pin mounted onto said first face of said inner piston and a first cylindrical cavity in said end cap, said first cavity connected to said hydraulic UP port of said first chamber, said first cavity having a slightly bigger diameter than said pin, said pin forming a first annular orifice between said pin and said first cavity when entering said first cavity, thus forcing hydraulic fluid in said first hydraulic chamber to flow out through said first annular orifice, thereby slowing down said outer piston;said pin having a variable longitudinal profile, said first annular orifice cross section area decreasing as said pin moves into said first cavity, said profile shaped to provide a desired deceleration of said outer piston;said means for downstroke cushioning further comprising a first check valve between said hydraulic UP port and said first hydraulic chamber, said valve enabling one way flow from said hydraulic UP port to said first hydraulic chamber and blocking flow in the opposite direction, thus enabling unrestricted hydraulic flow into said first hydraulic chamber on upstroke;said means for upstroke cushioning comprising a sleeve mounted onto said outer piston rod adjacent to said outer piston head and a second cylindrical cavity in said cylinder head, said second cavity connected to said hydraulic DOWN port of said second hydraulic chamber, said second cavity having a slightly bigger diameter than said sleeve, said sleeve forming a second annular orifice between said sleeve and said second cavity when entering said second cavity, thus forcing hydraulic fluid in said second hydraulic chamber to flow out through said second annular orifice, thereby slowing down said outer piston;said sleeve having a variable longitudinal profile, said second annular orifice cross section area decreasing as said sleeve moves into said second cavity, said profile shaped to provide a desired deceleration of said outer piston;said means for upstroke cushioning further comprising a second check valve between said hydraulic DOWN port and said second hydraulic chamber, said valve enabling one way flow from said hydraulic DOWN port to said second hydraulic chamber and blocking flow in the opposite direction, thus enabling unrestricted hydraulic flow into said second hydraulic chamber on downstroke. 18. The lifting system in accordance with claim 11, further comprising: at least one pulley affixed to the top of said outer piston;at least one cable wrapped around the top of said pulley, one end of each said cable anchored to a stationary point, a polished rod connected to the other end of said cable, the polished rod, the rod string and the downhole pump reciprocating at twice the speed and stroke of the outer piston. 19. The lifting system in accordance with claim 11, further comprising: at least one gear wheel affixed to the top of said outer piston;at least one chain wrapped around the top of said gear wheel, one end of each said chain anchored to a stationary point, a polished rod connected to the other end of said chain, the polished rod, the rod string and the downhole pump reciprocating at twice the speed and stroke of the outer piston. 20. The lifting system in accordance with claim 11, further comprising: at least one sheave affixed to the top of said outer piston;at least one belt wrapped around the top of said sheave, one end of each said belt anchored to a stationary point, a polished rod connected to the other end of said belt, the polished rod, the rod string and the downhole pump reciprocating at twice the speed and stroke of the outer piston.