CROSS REFERENCE TO RELATED APPLICATION [0001] This application claims the benefit of and incorporates by reference the entirety of US Provisional Patent Application No. 62281115 filed on January 20, 2016, U.S. Provisional Application No. 62345512 filed on June 3, 2016 and U.S. Provisional Application No. 62345541 filed on June 3, 2016.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] Not applicable.

SEQUENCE LISTING, TABLE OR COMPUTER

PROGRAM ON COMPACT DISC

[0003] Not applicable.

FIELD OF INVENTION

[0004] This invention relates generally to pneumatic circuits utilizing directional control valves and more particularly to systems and methods for operating same.

BACKGROUND OF THE INVENTION [0005] Certain industrial applications require the charging and subsequent discharging of a working vessel with compressed gas in a repeated cycle. For example, in blow molding applications, a part mold (the working vessel) is filled with compressed gas during the molding process. After the part is formed, the compressed gas used to pressurize the mold is subsequently discharged from the mold. The process of charging (i.e., pressurizing) and subsequent discharging (i.e., depressurizing) of the mold with compressed gas is repeated for the next molded part.

[0006] Another example of a process involving repeated charging and discharging of a working vessel is the actuation of a single-acting pneumatic cylinder (a/k/a "actuator"). The fluid chamber of a single-acting pneumatic cylinder is a working vessel that is actuated by a single compressed gas line, and for which compressed gas (typically air) is used to effect either the retraction or extension stroke of a piston and rod assembly within the cylinder, while a spring is used to effect the opposing stroke (i.e., extension or retraction, respectively). As such, repeated extension and retraction of the piston and rod assembly requires repeated charging and discharging of the compressed gas side (chamber) of the pneumatic cylinder. The mold in a blow molding application, and the cylinder in a single-acting pneumatic cylinder, can each be regarded as a working (pressure) vessel, which in general is a volume of space that is pressurized with compressed gas.

[0007] A double-acting pneumatic cylinder uses the force of fluid (typically air) to move in both the extension and retraction strokes. The typical double-acting cylinder includes a piston housing (the cylinder) that encapsulates a piston that can slidably move within the housing along its length. The piston divides the piston housing into two chambers (a first and second chamber), the size of each chamber is variable and depends upon the location of the piston within the housing. Thus, a double-acting cylinder has two ports, one for each chamber, to allow air in. Air entering into one chamber and pressing against the piston will effect an extension (or retraction) stroke of the piston, while air entering the other chamber and pressing against the piston will effect a respective counter retraction (or extension) stroke of the piston. When the fluid in one chamber is at a higher pressure than the fluid in the other chamber, the piston will be caused to move in the direction of the low pressure chamber. Some double-acting cylinders include biasing springs within one or more of the chambers so as to regulate the expansion of the chambers; the biasing spring typically serving to counteract a chosen amount of movement of the piston into the chamber in which the spring is located. As with the single-acting pneumatic cylinder, the chambers of a double-acting pneumatic cylinder can also each be regarded as a working pressure vessel.

[0008] The processes of pressurizing and depressurizing (or charging and discharging) a working vessel (or pressure vessel) in applications such as are described above are often controlled by a 3 -way valve. A typical 2-position, 3 -way, 3 -port valve (hereafter called a 3 -way valve) is defined for purposes of this application as one that selectively connects three fluid ports in one of two respective port connectivity positions. A schematic diagram of the port connectivity provided by a standard 3 -way valve 1 is shown in Figure 1, where the labels PI and P2 correspond to first and second valve positions, respectively. Although various arrangements of the three ports are possible, in keeping with a conventional usage, the three ports will be respectively referred to here as the supply (conventionally labeled in technical drawings with the letter "S"), exhaust (conventionally labeled in technical drawings with the letter Έ"), and the outlet port (conventionally labeled in technical drawings with the letter "A"). Given this nomenclature, a standard 3 -way valve can either be configured into a first position PI, which provides a port connectivity configuration in which outlet port A is connected to supply port S, and exhaust port E is isolated; or into a second position P2, which provides a port connectivity configuration in which outlet port A is connected to (in fluid communication with) exhaust port E, and supply port S is isolated (fluid flow between the supply port and all of the other ports of the valve is prevented). As shown in Figure 2, supply port S is in fluid communication with pressure supply 2, which supplies a compressed fluid for the relevant industrial application. Exhaust port E is in fluid communication with (discharges to) an exhaust 6, which is typically atmosphere or exhaust piping or receptacle. In some cases, a 3 -way valve may include a third position F3, which corresponds to a third port connectivity configuration, such as one in which all ports are isolated. In typical operation, however, only the first and second valve positions (i.e., port connectivity configurations) PI, P2 are used.

[0009] Figures 2 and 3 show a typical configuration in which a 3 -way valve 1 is used to control the charging and discharging of a working vessel 3 via gas line 30. As shown in Figure 2, when valve 1 is in a first position PI, outlet port A is connected to supply port S, and working vessel 3 is charged (i.e., pressurized). As shown in Figure 3, when valve 1 is in a second position P2, outlet port A is connected to exhaust port E, and the compressed gas in working vessel 3 is discharged through exhaust port E. Although valve 1 might be moved between positions PI and P2 manually, in most automated applications, valve 1 is moved between the first and second positions PI, P2 via electrical actuation, such as via direct or pilot-actuated solenoid operation.

[0010] The processes of pressurizing and depressurizing (or charging and discharging) a working vessel in applications such as are described above are also often controlled by a 2-way, 2-position valve (hereafter called a 2-way valve). The repeated actuation of a working vessel such as the chamber of a single-acting actuator or double-acting actuator can be implemented by using 2-way valves. A schematic representation of an application using two 2-way valves is shown in Figures 36. As seen in the figure, a 2 -way valve has a first port and a second port. A 2-way valve is defined for purposes of this application as one that be configured into a first valve position PI and a second valve position P2, where in the first valve position PI the two ports are in fluid isolation, and where in the second valve position P2 the two ports are in fluid communication. In a typical application as shown in Figure 36, two 2-way valves can be used to pressurize and subsequently depressurize a working vessel by connecting a first 2-way valves to a pressure source and the working vessel and by connecting a second 2-way valve to an exhaust and to the same working vessel. As shown in Fig. 36, by placing the first 2-way valve in position P2 and the second 2-way valve in position PI, the working vessel will be fluidly connected to the pressure source and the working vessel will be pressurized. By switching both valves to the opposition position, specifically by switching the first 2-way valve in position PI and the second 2-way valve in position P2, the working vessel will then be fluidly connected to the exhaust and the working vessel will be depressurized.

[0011] The pneumatic circuit of the prior art, whether using 2-way or 3 -way valves suffers from the fact that it is not energy efficient and is not deployed in an energy efficient manner. For example, in the case of a 3 -way valve circuit, during the course of a typical repeated charge and discharge cycle( as illustrated in Figures 2 and 3), the entire mass of compressed gas contained within working vessel 3 is vented to atmosphere after each cycle. This discharge is inefficient and requires the provision of a new volume of compressed gas for each application. The same discharge occurs with prior art pneumatic circuits using 2-way valves. Rather than discard the entire mass of compressed gas during each discharge phase of the cycle, it would be desirable to reduce the consumption of compressed air by temporarily storing a portion of the compressed gas during the discharge process, and subsequently reusing a portion of the stored compressed gas during the following charging portion of the cycle.

SUMMARY OF THE INVENTION

[0012] The present invention is directed to improved systems and methods that reserve compressed gas for use in an application cycle. More specifically, this application describes embodiments of energy-saving charge/discharge systems and methods that use 2 -way valve circuits and 3 -way valve circuits to control the repeated charging and discharging of a working vessel in a manner that enables the storage and subsequent reuse of compressed gas during the repeated charge and discharge cycle. In contrast to the methods of the prior art, the present invention method does not discard the entire mass of compressed gas during each discharge phase of the cycle. An energy savings results from the recycling of compressed gas, which reduces the net consumption of compressed gas for a given charge/discharge cycle of a given working vessel.

[0013] The present invention systems and methods allow for the storage and reuse of compressed gas with a minimal amount of additional apparatus, and with minimal requirement for system reconfiguration, relative to a conventional implementation. A minimum amount of apparatus is required to implement the recycling of compressed gas. The present invention systems and methods reduce the consumption of compressed air by permitting the temporary storing of a portion of the compressed gas in a pressure reservoir during the discharge process. The valves can be actuated to reuse a portion of the stored compressed gas during the following charging portion of the cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic diagram of port connectivity for a standard 2 -position,

3-way, 3-port valve.

[0015] Figure 2 is a schematic diagram of a standard configuration for a working vessel charging via a standard 3-way control valve, the diagram showing the control valve in the first position.

[0016] Figure 3 is a schematic diagram showing a standard configuration for a working vessel discharging via a standard 3-way control valve, the diagram showing the control valve in the second position.

[0017] Figures 4-7 illustrate an embodiment pneumatic system and method for the repeated charging and discharging of a working vessel using a plurality of standard 3-way valves. The figures show the configuration of the valves as the system goes through the states in which the pressure vessel is charged and discharged. The shown system depicting an optional arrangement having sensors and a controller.

[0018] Figures 8-11 illustrate an alternate embodiment pneumatic system and method for the repeated actuation of a single-acting actuator using a plurality of standard 3-way valves. The figures show the configuration of the valves as the system goes through the states in which the cylinder is configured between the first and second actuation positions. The figures illustrate a single-acting rod-style cylinder that uses pressurization for its retracted state, but this embodiment is not meant to be limiting.

[0019] Figures 12-19 illustrate an embodiment pneumatic system and method for the repeated actuation of a double-acting actuator using the temporary storage of a portion of compressed gas during the discharge process, and subsequently reusing a portion of the stored compressed gas during the following charging portion of the cycle. The disclosed system employs a plurality of standard 3 -way control valves to effect the principle. The figures show the configuration of the valves as the system goes through the states in which the chambers of the double-acting actuator are charged and discharged.

[0020] Figures 20-23 illustrate an embodiment pneumatic system and method for the repeated charging and discharging of a working vessel using a plurality of standard 2-way valves. The figures show the configuration of the valves as the system goes through the states in which the working vessel is charged and discharged.

[0021] Figures 24-27 illustrate an alternate embodiment pneumatic system and method for the repeated actuation of a single-acting actuator using a plurality of standard 2-way valves. The figures show the configuration of the valves as the system goes through the states in which the cylinder is configured between the first and second actuation positions. The figures illustrate the actuator as a single-acting rod-style cylinder that uses pressurization for its retracted state, but this embodiment is not meant to be limiting.

[0022] Figures 28-35 illustrate an alternate embodiment system and method for the repeated actuation of a double-acting actuator using a plurality of standard 2-way valves. The figures show the configuration of the valves as the system goes through the states in which the actuator is configured between the first and second actuation positions.

[0023] Figure 36 shows a typical application in which two 2-way valves can be used to pressurize and subsequently depressurize a working vessel.

DETAILED DESCRIPTION [0024] The inventive systems and methods will now be described in the context of their preferred embodiments. The inventive method of the temporary storage and re-use of compressed gas during the repeated charging and discharging of a working vessel can be implemented by using a plurality of standard 3 -way valves la, lb, configured as shown in Figures 4-7. An embodiment energy saving method employs a fluid supply 2, a working vessel 3, a fluid reservoir 4, and first three-way control valve la and second three-way control valve lb. Each three-way control valve la, lb respectively includes a supply port Sa, Sb, an exhaust port Ea, Eb and an outlet port Aa and Ab. Valves la, lb can each can be configured into a first valve position PI and a second valve position P2. In the first valve position PI, supply port S is in fluid communication with outlet port A, while exhaust port £ is isolated. In the second valve position P2, exhaust port £ is in fluid communication with outlet port A, while supply port S is isolated. Working vessel 3 and reservoir 4 each respectively include at least one fluid port 7, 8.

[0025] The ports of each respective component are connected as follows. Supply port Sa of first valve la is connected to fluid supply 2. Exhaust port Ea of first valve la is connected to fluid port 8 of reservoir 4 via line 31. Outlet port Ab of second valve lb is connected to fluid port 7 of working vessel 3 via line 30. Supply port Sb of second valve lb is connected to outlet port Aa of first valve la. Exhaust port Eb of second valve lb is connected to exhaust 6.

[0026] As illustrated in Figure 4, working vessel 3 is maintained in a charged state when the first and second valves la, lb are configured respectively in the first valve position PI. As illustrated in Figure 6, working vessel 3 is maintained in a discharged state when first and second valves la, lb are configured respectively in the second valve position P2.

[0027] Working vessel 3 is configured from the charged state of Figure 4 and into the discharged state of Figure 6 by first configuring first valve la from the first valve position PI into the second valve position P2. This is shown in Figure 5. The configuration of Figure S enables compressed gas to flow from working vessel 3 to reservoir 4. Subsequently configuring second valve lb from the first valve position PI to the second valve position P2 (Figure 6) discharges the remaining compressed gas in working vessel 3 to exhaust.

[0028] Working vessel 3 is configured from the discharged state of Figure 6 to the charged state of Figure 4 by first configuring second valve lb from the second valve position P2 into the first valve position PI. This is shown in Figure 7. This configuration enables compressed gas to flow from reservoir 4 to working vessel 3. Subsequently configuring first valve la from the second valve position P2 to the first valve position PI as shown in Figure 4 fully charges the pressure vessel via supply 2.

[0029] The process of compressed gas savings can be modelled as follows. Assuming ideal gas constitutive behavior, isothermal processes, and constant-volume chambers, one can show that the high-pressure equilibrium pressure is given by: where VR is the volume ratio between the reservoir 4 and pressure vessel 3, given by:

where V _A and VB are the volumes of a working vessel 3 and reservoir 4, respectively, k denotes the charge/discharge cycle (where ft=l is the first cycle), is the high-pressure equilibrium

pressure at the current charge/discharge cycle, is the low-pressure equilibrium pressure

during the previous change/discharge cycle, and Ps is the supply pressure. Given similar assumptions, the low-pressure equilibrium pressure at the current cycle is given by:

where is the low-pressure equilibrium pressure at the current charge/discharge cycle k, is the high-pressure equilibrium pressure at the current cycle given by (1), and PATM is

atmospheric pressure. Equations (1) and (3) can be combined to yield a single recursive equation for the low-pressure equilibrium pressure:

This equation is a first-order difference equation of the form:

[0030] Assuming reservoir 4 is fully depressurized at the start of the charge/discharge process, the initial pressure, PLPE(0) in (9) is PATM- Equation (9) is stable if and only if a < 1 , which based on equation (6), will always be true. As such, the difference equation (9) will converge at a sufficient number of cycles to a steady-state equilibrium pressure given by:

Substituting equations (6-8) into equation (11) yields a low-pressure equilibrium pressure in the steady state of:

Combining equations (9) and (10), one can show that the number of cycles required to obtain a fraction γ of the steady state pressure, assuming the initial pressure in the reservoir is PATM, is given by:

[0031] Assuming, for example, a reservoir 4 of equal volume to the pressure vessel 3

(i.e., F/f=l), one can show from equation (12) that the low-pressure equilibrium pressure will reach 95% of its steady-state value (i.e., 7 ^* = 0.95) after three cycles. Assuming the system reaches the steady-state low-pressure equilibrium pressure given by equation (12), and continuing the assumptions of ideal gas behavior and an isothermal process, the ratio of mass recycled during each cycle to total charge mass can be written as: where is the mass of compressed gas recycled from the previous cycle and is the total

mass of compressed gas required to charge working vessel 3. The amount of mass required to charge working vessel 3 without recycling is given by:

where RT is the product of the ideal gas constant and the nominal gas temperature (i.e., a constant under the assumed isothermal conditions). The amount of mass required to charge vessel 3 with recycling is given by:

As such, the amount of compressed gas required for each charge cycle relative to the amount without recycling is given by:

and therefore the compressed gas savings relative to a standard system is given by:

[0032] Assuming, for example, reservoir 4 is of equal volume to pressure vessel 3 (i.e., atmospheric pressure of 0.1 MPa (1 bar), and a supply pressure of 0.6 MPa (6 bars), the steady-state low-pressure equilibrium pressure would be: such that the compressed gas savings would be and the savings relative to a standard

process given by In the limit that reservoir 4 becomes much larger than pressure vessel 3, assuming the same ratio of atmospheric to supply pressure (1:6), the steady- state low-pressure equilibrium pressure will approach: such that the compressed gas savings will approach and the savings relative to a standard

process will similarly approach (50% savings). In the case that no pressure reservoir 3 is used ( the steady-state equilibrium pressure will be the relative mass

requirement , and the relative savings (i.e., no savings possible without a pressure

reservoir. The foregoing discussion regarding the modelling of compressed gas savings is equally applicable to the inventive 2-way valve circuits discussed below.

[0033] In a further embodiment, the method for the temporary storage and re-use of compressed gas can be employed to effect the repeated actuation of a single-acting actuator 20 (e.g., a working vessel) by using a plurality of standard 3 -way valves 1. This method is shown in Figures 8-12. The embodiment energy saving method employs a fluid supply 2, a single-acting actuator 20, a fluid reservoir 4, a first three-way control valve la and a second three-way control valve lb. Each three-way control valve la, lb includes a supply port S, at least one exhaust port E and an outlet port A. Valves la, lb can each be configured into a first valve position and a second valve position. In the first valve position, supply port S is in fluid communication with outlet port A, while exhaust port E is isolated. In the second valve position, outlet port A is in fluid communication with exhaust port E, while supply port S is isolated. The single-acting actuator 20 and reservoir 4 respectively include at least one fluid port 7, 8.

[0034] The ports of each respective component are connected as follows. Outlet port Ab of second valve lb is connected via line 30 to fluid port 7 of actuator 20. Supply port Sb of second valve lb is connected to outlet port Aa of first valve la. Exhaust port Eb of second valve lb is connected to exhaust 6. Supply port Sa of first valve la is connected to fluid supply 2. Exhaust port Ea of first valve la is connected via line 31 to port 8 of reservoir 4.

[0035] As illustrated in Figure 8, actuator 20 is configured into a first actuator position

(piston retracted) when first valve la and second valve lb are configured respectively in the first valve position. As illustrated in Figure 10, actuator 20 is configured into a second actuator position when first valve la and second valve lb are configured respectively in the second valve position.

[0036] Single-acting actuator 20 is configured to move from the first actuator position of

Figure 8 to the second actuator position of Figure 10 by first configuring first valve la from the first valve position into the second valve position as shown in Figure 9. This configuration of valve la enables compressed gas to flow from the pressurized chamber 25 of actuator 20 to reservoir 4. Subsequently configuring the second valve lb from the first valve position to the second valve position as shown in Figure 10 allows the discharge of the remaining compressed gas in the actuator chamber 25 to exhaust 6, which configures actuator 20 into the second actuator position (extended piston).

[0037] Single-acting actuator 20 is configured to move from the second actuator position depicted in Figure 10 into the first actuator position of Figure 8 by first configuring second valve lb from the second valve position into the first valve position. This is shown in Figure 11. The valve configurations of Figure 11 enable compressed gas to flow from reservoir 4 to the pressure chamber 25 of actuator 20. Subsequently configuring first valve la from the second valve position to the first valve position as shown in Figure 8 fully charges actuator chamber 25 and configures actuator 20 into the first actuator position (piston retracted). [0038] The inventive system and method of temporarily storing a portion of the compressed gas during the discharge process, and subsequently reusing a portion of the stored compressed gas during the following charging portion of the cycle to reduce the consumption of compressed air can be applied in systems employing a double-acting pneumatic actuator. An embodiment method for an exemplary pneumatic circuit including such an actuator 120 is shown in Figures 12-19.

[0039] A double-acting pneumatic actuator is one that is configured into one of two piston positions (a first actuator position and second actuator position) via pneumatic forces. In the case of linear actuator 120, these two positions can be regarded as retraction and extension of the piston and rod assembly 121 (the assembly 121 comprising piston 122 and rod 123). A double-acting pneumatic actuator 120 is actuated by compressed gas entering in from two compressed gas lines 130a, 130b, wherein compressed gas (typically air) is used to effect both the retraction and extension stroke of piston and rod assembly 121 within housing (shown as a cylinder in the drawings) 126 of actuator 120. The repeated extension and retraction of the piston and rod assembly 121 requires repeated charging and discharging of the compressed gas chambers 124, 125 of the housing 126. It should be noted that the embodied representation of the double-acting pneumatic actuator as a rod-style cylinder is not meant to be limiting. Any double-acting pneumatic actuator can be used in the inventive application.

[0040] The method for the temporary storage and re-use of compressed gas during the repeated actuation of a double-acting actuator 120 can advantageously be implemented by using a plurality of standard 3 -way valves 1, configured as shown in the exemplary system 102 shown in Figures 12-19. For purposes of illustration, the configuration shown depicts actuator 120 for which pressurization of chamber 125 of housing 126 and depressurization of chamber 124 of housing 126 causes retraction of piston and rod assembly 121. Depressurization of chamber 125 of housing 126 along with pressurization of chamber 124 of housing 126 moves piston and rod assembly 121 to the extension configuration.

[0041] An embodiment energy saving system and method employs a fluid supply 2, a double-acting actuator 120, a fluid reservoir 4, and first, second, third and fourth three-way control valves la, lb, lc, Id. Each three-way control valve employs a supply port S, an exhaust port £, and an outlet port A. Each valve la, lb, lc, Id can be configured into a first valve position depicted as PI and a second valve position depicted as P2. In the first valve position, the supply port S is in fluid communication with the outlet port A, while the exhaust port E is isolated. In the second valve position, the exhaust port E is in fluid communication with the outlet port A, while the supply port is isolated. The double-acting actuator 120 includes at least first and second actuator ports 128, 129, while the reservoir 4 includes at least one fluid port 8.

[0042] The ports of each respective component are connected as follows. Outlet port Ab of second valve lb is connected via line 130a to first actuator port 128 of actuator 120. Supply port Sb of second valve lb is connected via line 132a to outlet port Aa of first valve la. Exhaust port Eb of second valve lb is connected to exhaust 6. Supply port Sa of first valve la is connected to supply 2. Exhaust port Ea of first valve la is connected via line 131a to reservoir 4. Outlet port Ac of third valve lc is connected via line 130b to second actuator port 129 of actuator 120. Supply port Sc of third valve lc is connected via line 132b to outlet port Ad of fourth valve Id. Exhaust port Ec of third valve lc is connected to exhaust 6. Supply port Sd of fourth valve Id is connected to fluid supply 2. Exhaust port Ed of fourth valve Id is connected via line 131b to reservoir 4. [0043] As illustrated in Figure 12, actuator 120 is configured into a first actuator position when first and second valves la, lb are configured respectively in the first valve position PI, while the third and fourth valves lc, Id are configured in the second valve position P2. As illustrated in Figure 16, actuator 120 is configured into a second actuator position when the first and second valves la, lb are configured respectively in the second valve position P2, while the third and fourth valves lc, Id are configured in the first valve position PI .

[0044] Double-acting cylinder 120 is configured to move from the first actuator position of Figure 12 and into the second actuator position shown in Figure 16 by a sequence of valve configurations. In the first configuration (state 1), valve la is in the first position, valve lb is in the first position, valve lc is in the second position and valve Id is in the second position. This configuration of valves causes fluid from fluid supply to flow into chamber 125 of actuator 120 via valves la, lb and effect the retraction of piston assembly 121. The second configuration sequence involves maintaining all other valves in the configurations shown in Figure 12 and configuring first valve la from the first valve position and into the second valve position. This action is shown in Figure 13 and causes compressed gas in chamber 125 to flow from the pressurized chamber 125 of the actuator 120 to reservoir 4 (state 2). In the third configuration sequence, shown in Figure 14, while maintaining all other valves in the configuration of state 2 (Figure 13), second valve lb is configured from the first valve position to the second valve position. This last step discharges the remaining compressed gas in first actuator chamber 125 to exhaust 6 (state 3).

[0045] In the fourth configuration sequence, while maintaining all other valves in the configuration of state 3 (Figure 14), third valve lc is configured from the second valve position to the first valve position as shown in Figure IS (state 4). This causes compressed gas to flow from the reservoir 4 to the second chamber 124 of actuator 120. In the fifth sequence, while maintaining all other valves in their configuration of state 4 shown in Figure IS, fourth valve Id is configured from the second valve position to the first valve position to connect to fluid supply 2. This fifth configuration is shown in Figure 16 and completes the charging process of second actuator chamber 124, and completes the configuring of actuator 120 into the second actuator position (state 5).

[0046] Double-acting cylinder 120 can be configured to move from the second actuator position shown in Figure 16 and into the original first actuator position shown in Figure 12 by another series of configuration sequences. In this respect, while maintaining all other valves in their configuration of state 5, fourth valve Id is configured from the first valve position into the second valve position as depicted in Figure 17 (state 6). This sixth configuration of valves la, lb, lc, Id results in compressed gas flowing from pressurized chamber 124 of actuator 120 to reservoir 4. In the next (seventh) configuration, while maintaining all other valves in their configuration of state 6, third valve lc is configured from the first valve position to the second valve position as shown in Figure 18. This configuration allows for the discharge of the remaining compressed gas in second actuator chamber 124 to exhaust (state 7). Once chamber 124 exhausts, then the eighth configuration sequence involves configuring second valve lb from the second valve position to the first valve position while all other valves are maintained in their configuration shown in Figure 18. This configuration action is shown in Figure 19 and causes compressed gas to flow from the reservoir 4 to the chamber 125 of actuator 120 (state 8). Configuring first valve la from the second valve position to the first valve position, while maintaining all other valves in their configurations of state 8, as indicated in Figure 12 completes the charging process of the first actuator chamber and completes the configuring of actuator 120 into the first actuator position.

[0047] The inventive systems and methods will now be described in the context of their

2-way valve preferred embodiments. Figure 36 is a schematic diagram of a standard configuration for a working vessel charging via two standard 2-way control valves. The configuration shows the pressurized state of the system. A preferred embodiment of the proposed systems and methods can be implemented by using a plurality of standard 2-way valves 201a, 201b, 201c configured as shown in Figs. 20-23. As seen in the figures, a 2-way valve can be configured into a first valve position and a second valve position, where in the first valve position the two ports (a first port A and second port B) are in fluid isolation, and where in the second valve position the two ports are in fluid communication.

[0048] The embodiment energy saving method of Figs. 20-23 includes a fluid supply 2, a working vessel 3, a fluid reservoir 4, and first, second, and third 2-way control valves 201a, 201b and 201c. Working vessel 3 and reservoir 4 respectively each include at least one fluid port 7, 8. The respective first ports Aa, Ab, Ac of the first, second, and third valves 201a, 201b, 201c are connected to fluid port 7 of working vessel 3. Second port Ba of first valve 201a is connected to a fluid supply 2. Second port Bb of second valve 201b is connected to exhaust 6. Second port Be of third valve 201c is connected to fluid port 8 of reservoir 4.

[0049] As illustrated in Figure 20, working vessel 3 is maintained in a charged state when first valve 201a is configured in the second valve position (i.e., fluid communication), while the second and third valves 201b, 201c are configured respectively in the first valve position (i.e., fluid isolation). As illustrated in Figure 22, working vessel 3 is maintained in a discharged state when first valve 201a is configured in the first valve position, second valve 201b is in the second valve position, and third valve 201c in the first valve position.

[0050] Working vessel 3 is configured from the charged state Figure 20 into the discharged state of Figure 22 by: configuring first valve 201a from the second valve position into the first valve position and subsequently configuring third valve 201c from the first valve position to the second valve position. These configurations are shown in Figure 21. The valve configurations of Figure 21 enable compressed gas to flow from working vessel 3 to reservoir 4. After achieving the configuration of Figure 21, third valve 201c is configured from the second valve position to the first valve position and men second valve 201b is configured from the first valve position to the second valve position. These steps are shown in Figure 22. The configurations of Figure 22 discharge the remaining compressed gas from the pressure vessel to exhaust.

[0051] Working vessel 3 is configured from the discharged state of Figure 22 to the charged state shown in Figure 20 by configuring second valve 201b from the second valve position to the first valve position and subsequently configuring third valve 201c from the first valve position to the second valve position as shown in Figure 23. These valve configurations of Figure 23 enable compressed gas to flow from reservoir 4 to pressure vessel 3. Next, third valve 201c is configured from the second valve position to the first valve position and first valve 201a is configured from the first valve position to the second valve position. These configurations are shown in Figure 20 and complete the charging process of the pressure vessel.

[0052] In a further embodiment, the method for the temporary storage and re-use of compressed gas can be employed to effect the repeated actuation of a single-acting actuator 20 (e.g., the fluid chamber of which is a working vessel) by using a plurality of standard 2-way valves 201a, 201b, 201c. This method is shown in Figs. 24-27. The embodiment energy saving system and method employs a fluid supply 2, a single-acting actuator 20, a fluid reservoir 4 and first, second, and third 2 -way control valves 201a, 201b, 201c. The single-acting actuator 20 and reservoir 4 respectively include at least one fluid port 7, 8. The respective first ports Aa, Ab, Ac of the first, second, and third valves 201a, 201b, 201c are connected to fluid port 7 of actuator 20. Second port Ba of first valve 201a is connected to supply 2. Second port Bb of second valve 201b is connected to exhaust. Second port Be of third valve 201c is connected to fluid port 8 of reservoir 4.

[0053] As illustrated in Figure 24, actuator 20 is configured into a first actuator position when first valve 201a is configured in the second valve position (i.e., fluid communication), while second and third valves 201b, 201c are configured respectively in the first valve position (i.e., fluid isolation). As illustrated in Figure 26, actuator 20 is configured into a second actuator position when first valve 201a is configured in the first valve position, second valve 201b is configured in the second valve position and third valve 201c in the first valve position.

[0054] Single-acting cylinder 20 is configured to move from the first actuator position shown in Figure 24 into the second actuator position shown in Figure 26 by undergoing a first and second configuration sequence. The first configuration sequence involves maintaining second valve 201b in the first configuration and configuring first valve 201a from the second valve position into the first valve position and then subsequently configuring third valve 201c from the first valve position to the second valve position. This configuration of valves is shown Figure 25 and enables compressed gas to flow from the pressurized side of the actuator 20 to reservoir 4. The second configuration sequence involves maintaining first valve 201a in the first configuration and configuring third valve 201c from the second valve position to the first valve position and subsequently configuring second valve 201b from the first valve position to the second valve position. These latter configurations are shown in Figure 26 and result in the discharge of the remaining compressed gas in the actuator chamber 25 to exhaust, completing the discharging process of actuator chamber 25 and completing the configuring of actuator 20 into the second actuator position (shown in this embodiment as piston extended).

[0055] Actuator 20 is configured to move from the second actuator position of Figure 26 and on into the first actuator position of Figure 24 by undergoing two further configuration sequences (the third and fourth configuration sequences). The third configuration sequence involves maintaining first valve 201a in the first position while configuring second valve 201b from the second valve position to the first valve position and subsequently configuring third valve 201c from the first valve position to the second valve position. These configurations are shown in Figure 27. The configurations of Figure 27 enables compressed gas to flow from reservoir 4 to actuator chamber 25. After completing the third configuration sequence, the fourth configuration sequence proceeds. In this fourth configuration sequence second valve 201b is maintained in the first valve position while configuring third valve 201c from the second valve position to the first valve position and subsequently configuring first valve 201a from the first valve position to the second valve position as shown in Figure 24. The configurations of Figure 24 allow for the completion of the charging process of actuator chamber 25 resulting in the movement of piston and rod assembly 21 into the retracted position, which is the first actuator position.

[0056] The method for the temporary storage and re-use of compressed gas during the repeated actuation of a double-acting actuator 120 can advantageously implemented by using a plurality of standard 2-way valves 201a, 201b, 201c, 201d, 201e, 201f configured as shown in the exemplary system 202 shown in Figures 28-35. For purposes of illustration, the configuration shown depicts actuator 120 for which pressurization of chamber 125 of housing 126 and depressurization of chamber 124 of housing 126 causes retraction of piston and rod assembly 121. Depressurization of chamber 125 of housing 126 along with pressurization of chamber 124 of housing 126 moves piston and rod assembly 121 to the extension configuration. It should again be noted that the embodied representation of the double-acting pneumatic actuator as a rod-style cylinder is not meant to be limiting. Any double-acting pneumatic actuator can be used in the inventive application.

[005η 2-way valves 201a, 201b, 201c, 201d, 201 e, 201f are configured as shown in the exemplary system 202 shown in Figures 28-35. The 2-way valve embodiment of the energy saving system and method employs a fluid supply 2, a double-acting actuator 120, a fluid reservoir 4, and first, second, third, fourth, fifth, and sixth 2-way control valves 201a, 201b, 201c, 201d, 201 e, 201f. Double-acting actuator 120 includes a first actuator port 128 and second actuator port 129. Reservoir 4 includes at least one fluid port 8. The respective first ports Aa, Ab, Ac of the first, second, and third valves 201a, 201b, 201c are connected to first port 128 of actuator 120, which comprises two chambers, 124, 125. The respective first ports Ad, Ae, Af of the fourth, fifth, and sixth valves 201d, 201 e, 201f are connected to second port 129 of actuator 120. The second ports of first and sixth valves 201a, 201f are connected to fluid supply 2. The second ports of second and fifth valves 201b, 201 e are connected to exhaust The second ports of third and fourth valves 201c, 201d are connected to fluid port 8 of reservoir 4.

[0058] As illustrated in Figure 28, actuator 120 is configured into a first actuator position

(piston assembly retracted) when valves 201b, 201c, 201d, 201f are configured respectively in the first valve position (i.e., fluid isolation) and first and fifth valves 201a, 201e are configured respectively in the second valve position (i.e., fluid communication). As illustrated in Figure 32, actuator 120 is configured into a second actuator position (chamber 124 fully charged and piston 122 assembly fully extended) when the second and sixth valves 201b, 201f are configured respectively in the second valve position, while the remaining valves 201a, 201c, 201d, 201e are configured respectively in the first valve position.

[0059] Double-acting cylinder 120 is configured to move from the first actuator position of Figure 28 and into the second actuator position of Figure 32 by manipulating the valves through a series of configuration sequences described as follows. In the first configuration sequence, while maintaining all other valves in the valve positions shown in Figure 28, first valve 201a is configured from the second valve position into the first valve position and then third valve 201c is configured from the first valve position to the second valve position. This completed configuration sequence is shown in Figure 29 and enables compressed gas to flow from chamber 125 of actuator 120 to reservoir 4. In the second configuration sequence, while maintaining all other valves in the valve positions shown in Figure 29, third valve 201c is configured from the second valve position to the first valve position and then subsequently second valve 201b is configured from the first valve position to the second valve position. This completed configuration sequence is shown in Figure 30 and discharges the remaining compressed gas in the first actuator chamber 125 to exhaust In the third configuration sequence, while mamtaining all other valves in the valve positions shown in Figure 30, fifth valve 201e is configured from the second valve position to the first valve position and then subsequently fourth valve 201d is configured from the first valve position to the second valve position. This completed configuration sequence is shown in Figure 31 and enables compressed gas to flow from reservoir 4 to the chamber 124 of actuator 120. In the fourth configuration sequence, while maintaining all other valves in the valve positions shown in Figure 31, fourth valve 201d is configured from the second valve position to the first valve position and then sixth valve 201f is configured from the first valve position to the second valve position. This completed configuration sequence is shown in Figure 32 and completes the charging process of second actuator chamber 124 and completes the configuring of actuator 120 into the second actuator position.

[0060] Double-acting cylinder 120 is configured to move from the second actuator position of Figure 32 into the first actuator position of Figure 28 by manipulating the valves through a series of configuration sequences described as follows. In the fifth configuration sequence, while maintaining all other valves in the valve positions of Figure 32, sixth valve 201f is configured from the second valve position into the first valve position and then fourth valve 201d is configured from the first valve position to the second valve position. This completed sequence is shown in Figure 33 and enables compressed gas to flow from the pressurized chamber 124 to reservoir 4. In the sixth configuration sequence, while all other valves are maintained in their positions shown in Figure 33, fourth valve 201d is configured from the second valve position to the first valve position and then fifth valve 201e is configured from the first valve position to the second valve position. This completed sequence is shown in Figure 34 and discharges the remaining compressed gas in the second actuator chamber 124 to exhaust. In the seventh configuration sequence, while all other valves are maintained in the positions shown in Figure 34, second valve 201b is configured from the second valve position to the first valve position and then third valve 201c is configured from the first valve position to the second valve position. This completed configuration sequence is shown in Figure 35 and enables compressed gas to flow from reservoir 4 to first chamber 125 of actuator 120. In the eighth configuration sequence, while maintaining all other valves in their valve position of Figure 35, third valve 201c is configured from the second valve position to the first valve position and then first valve 201a is configured from the first valve position to the second valve position. This completed sequence results in the valve positions of shown in Figure 28 and completes the charging process of first actuator chamber 125 and also completes the configuring of actuator 120 into the first actuator position.

[0061] In any of the systems and methods described and shown in this application reservoir 4 can include a pressure sensor 60 and controller 50 to control timing of the periods during which fluid is moving into or out of the reservoir (also known as the "dwell" periods). This option is shown in Figures 4-7. The reservoir may also include additively or separately, a ball valve to empty the reservoirs if needed. Any of the working vessels can include one or more pressure sensors 60 and the pressure equilibration process can be regulated such mat equilibration process is terminated when the rate of change of pressure falls below a predetermined threshold.

[0062] For purposes of satisfying the required dwell times, an embodiment system may include a controller 50 programmed to cause the valve to stop and remain in a configuration sequence in which fluid flows into or out of the reservoir for a specified period of time. The specified period of time can vary among configuration sequences during which fluid moves into the reservoir and fluid moves out of the reservoir. In one embodiment, the controller 50 determines the specified period of time for which the system remains in a configuration sequence based upon an input of the amount of time necessary for pressure in a working vessel (or chamber thereof) and reservoir 4 to equilibrate. In another embodiment system, the controller 50 will determine the specified period of time for which the valve remains in a configuration sequence using as an input the length of time required for the pressure difference between the working vessel 3 and reservoir 4 to fall below a predetermined threshold.

[0063] While exemplary embodiments are described herein, it will be understood that various modifications to the systems and methods described can be made without departing from the scope of the invention. The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.