WO2017201261A1 - Load normalized air pump - Google Patents

Abstract

The present disclosure provides pump apparatuses and systems and methods for operating pump apparatuses for compression of a gas. The pump includes a frame portion, a first and second compression cylinder, a connecting shaft is coupled to a first piston head and the second piston head in the respective compression cylinders and a first compression spring pivotally coupled to the frame portion at a first fixed pivot point and pivotally coupled to the connecting shaft at a first translating pivot point. The pump apparatus includes a second compression spring pivotally coupled to the frame portion at a second fixed pivot point and pivotally coupled to the connecting shaft at a second translating pivot point. The first translating pivot point and the second translating pivot point are configured to translate reciprocally and contemporaneously with the connecting shaft.

Description

Load Normalized Air Pump

RELATED APPLICATION

The present application claims priority to U. S. Provisional Patent Application No. 62/338,458, filed on May 18, 2016, entitled "Load Normalized Air Pump," which application is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to air compression systems.

BACKGROUND

Compressing air efficiently is a fundamentally difficult process. Modern reciprocating piston air compressors are about 10% efficient overall. Much of this low efficiency can be traced to the inefficiency of the compression process itself, as air generates heat when it's compressed. Further inefficiencies are rendered by the pump, however, and conventional reciprocating piston pumps alone are 30-50% efficient. The lost energy manifests as heat, vibration, and noise, all of which are prominent features of air compressor operation.

In terms of efficiency, slower speeds of a reciprocating piston compressor generally correspond to greater efficiency. Practical considerations are what dominate in the low-speed range. As a pump is slowed (from a design perspective), the flywheel of a compressor must increase in size and mass. Conserving for power and throughput yields an approximate cubic relation between flywheel inertia and pump speed. In some instances, this is implemented for stationary air compressors. For portable/handheld air compressors, more efficient pumps with large and heavy flywheels driven by high-reduction belt drives are not practical, so the inefficiencies of higher speed pumps are endured.

Ideal compression of air manifests as a large cylinder with a slender aspect ratio, where the air is slowly compressed. A larger cylinder provides more surface area and thereby enable greater for heat dissipation. A slender aspect ratio yields even more surface area given a volume constraint. A slower action of the pump for compression permits more heat to escape through the cylinder walls, resulting in less work being done against the fluid. Furthermore, slow action of the compression pump allows for the use of more flexible valves that reduce pressure losses and improve air delivery per stroke.

With regards to compressor design, a tough issue to address is the highly nonlinear nature of the load curve seen by the piston head. The non-linear nature is manifested, for example, when one uses a bicycle hand pump. When pumping a bicycle hand pump the force experienced through the first part of the stroke is almost nothing, after which it spikes rapidly towards the end of the stroke and levels off as the air is delivered into a pressure vessel. In order to maximally utilize the power derived from an electric motor, the motor must experience a relatively constant voltage, current, torque, and speed. A simple solution has been employed since the beginning of air compression design: Use an inertial intermediary. A flywheel normalizes the load curve for the motor, providing excess power to the cylinder and absorbing excess power from the motor when each condition is necessary. The flywheel approach can effectively normalize the torque curve seen by an electric motor, as long as the running speed is high and the cylinder is relatively small.

However, as cylinder size for the compressor increases or the motor running speed decreases, the flywheel implemented for normalization becomes exponentially larger and heavier.

SUMMARY

Various embodiments disclosed herein provide pump apparatuses and systems and methods for operating pump apparatuses for compression of a gas. The pump apparatuses are configured to be driven by an electromechanical linear actuator.

In particular embodiments a pump apparatus includes a frame portion. The pump apparatus includes a first compression cylinder comprising a first piston head and having a first diameter is coupled to the frame portion. The pump apparatus includes a second compression cylinder comprising a second piston head and a second diameter different than first diameter is coupled to the frame portion. The pump apparatus includes an connecting shaft is coupled to the first piston head and the second piston head. The connecting shaft is configured to reciprocate and to drive the first piston head and the second piston head such that an expansion of a first volume in the first compression cylinder is contemporaneous with the contraction of a second volume in the second compression cylinder as the connecting shaft is moved in a first direction and such that a contraction of the first volume in the first compression cylinder is contemporaneous with the expansion of the second volume in the second compression cylinder as the connecting shaft is moved in a second direction opposite the first direction. The pump apparatus includes an intake valve in fluid

communication with the first compression cylinder to intake ambient air. The pump apparatus includes a transfer conduit for transferring compressed air from the first cylinder to the second cylinder. The pump apparatus includes a transfer valve in fluid communication with the transfer conduit to control the transfer of compressed through the transfer conduit. The pump apparatus includes an exhaust valve in fluid communication with the second compression cylinder to release compressed air from the second compression cylinder. The pump apparatus includes a first compression spring pivotally coupled to the frame portion at a first fixed pivot point and pivotally coupled to the connecting shaft at a first translating pivot point. The pump apparatus includes a second compression spring pivotally coupled to the frame portion at a second fixed pivot point and pivotally coupled to the connecting shaft at a second translating pivot point. The first translating pivot point and the second translating pivot point are configured to translate reciprocally and contemporaneously with the connecting shaft. The compression in the first and second compression springs changes as the first and second translating pivot points reciprocate with the connecting shaft.

In some implementations, the pump apparatus includes a linear actuator coupled to the connecting shaft configured to reciprocally drive the connecting shaft.

In certain implementations, the first compression cylinder and the second compression cylinder have differing diameters in a proportion in the range of 1.3: 1 to 2.5: 1.

In some implementations, the first compression spring and the second compression spring are configured to be axially aligned with one another, orthogonal to the connecting shaft, and at a maximum compression. The force of the first compression spring and the second compression spring is directed radially inward in opposing directions. The exhaust valve can be configured to exhaust compressed air from the first compression cylinder at the maximum compression.

In particular implementations, the first compression cylinder and the second compression cylinder are coaxially aligned along the connecting shaft

In some implementations, the connecting shaft comprises the transfer conduit. In certain implementations, the pump apparatus comprises a gas accumulator coupled to the second compression cylinder by the exhaust valve.

In various implementations, the transfer conduit includes the transfer valve.

In some implementations, one or more of the transfer valve, the intake valve and the exhaust valve are electronically controlled, via one or more processors.

In particular implementations, the frame portion forms at least a portion of at least one of the first compression cylinder and the second compression cylinder.

In certain implementations, the first compression spring and the second compression spring have a compression spring stiffness selected such that at a maximum pumping pressure, an average driving load along a main axis of the actuator shaft is within 70% of a peak load experienced by a linear actuator coupled to the connecting shaft for reciprocally driving the connecting shaft.

In various implementations, the pump apparatuses are driven by a linear actuator such as those disclosed in U. S. Patent Application No. 14/339,947 (U. S. Patent No. 9, 121,481) and U. S. Patent Application No. 15/200,389, which applications are incorporated herein by reference in their entireties. The linear actuator can be coupled to a drive shaft of the pump. The pump design renders efficient air compression and a normalized load curve that results in optimal electrical power use supplied by a linear actuator. As compared to a double-acting single-stage cylinder design, efficacy gains of more than 2x are realized and near-constant current and voltage can be supplied to the motor. The result is that, given maximum voltage and current constraints from a power source, approximately twice as much air is delivered by the pump.

The pump uses two main design techniques to provide a normalized load curve for the linear actuator. The first is to employ a two-stage compression design that produces different load curves for each direction of motion. The second is to use a particular geometric arrangement of springs to further normalize the load curves. The result of these two techniques is that, if such a pump was actuated by a person (as a bicycle pump, for example), the user would experience nearly-constant force in their hands in both the extension and contraction directions of motion. This behavior allows for maximal use of an electric power supply and correspondingly maximum air production given a linear-actuator driven air pump design. Particular embodiments provide a gas compression apparatus, consisting of a pump apparatus configured according to any one of the implementations or embodiments described herein and driven by a linear power source that is coupled to both the mobile pivots of the compression springs and the compression of gas in the cylinders via the piston heads. The linear power source generally performs two actions as motion happens to the left as per Fig. 3 : Intake of atmospheric gas into the large cylinder volume via an input valve and delivery of compressed gas through a delivery valve exiting the small cylinder into a gas accumulator, with the linear power source generally assisted by the compression springs that also drive the compression and delivery stroke in the small cylinder. The linear power source generally performs two actions as motion happens to the right as per the convention of Fig. 4:

Compression of the gas as gas travels from the large cylinder volume to the smaller cylinder volume via the gas conduit that is of a substantially small volume, in addition to energizing the compression springs. The linear power source having a relatively stable output force along the stroke that is within 70% of the peak force experienced by the linear power source in both directions.

Various embodiments provide a pump apparatus having two stages of compression and a method of operating the two stage compression pump apparatus. The first stage of compression occurs as air is transferred through the transfer conduit from a larger cylinder to a smaller cylinder of the pump apparatus. The gas present in the smaller cylinder experiences a rising pressure as the smaller cylinder expands in volume. The second stage of compression consists of the smaller cylinder first compressing within the smaller cylinder and then expelling the compressed gas through an exhaust valve in the smaller cylinder.

It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided such concepts are not mutually inconsistent) are contemplated as being part of the inventive subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing at the end of this disclosure are contemplated as being part of the inventive subject matter disclosed herein. It should also be appreciated that terminology explicitly employed herein that also may appear in any disclosure incorporated by reference should be accorded a meaning most consistent with the particular concepts disclosed herein. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the load normalized air pump.

FIG. 2 depicts a cross section of the air pump of FIG. 1

FIG. 3 depicts air spaces and valves within the pump of FIG. 1.

FIG. 4 shows air spaces and valves within the pump of FIG. 1

FIG. 5 shows the pump of FIG. 1 at the leftmost extreme of motion.

FIG. 6 depicts the pump of FIG. 1 at an intermediary position.

FIG. 7 depicts the pump of FIG. lat the singularity of the spring system, near the rightmost extreme of motion.

FIG. 8 depicts the pump of FIG. 1 at its rightmost extreme of motion.

FIG. 9 depicts the force curves (supplied by a linear actuator) that are required to drive the pump-and-spring system of FIG. 1.

DETAILED DESCRIPTION FIG. 1 shows a pump apparatus 100 for compressing a gas. The pump apparatus 100 includes two opposed compression cylinders 1,2 (housing

corresponding piston heads), a central connecting shaft 7, two compression springs 4a,b, pivoting coupling 6a,6b,5a,5b that place the springs 4a,b within a linkage 15a,b in two force member compression between the pivoting couplings 6a,6b,5a,5b of the respective springs 4a,b, and a supporting frame 3a, 3b that provides structural support for the fixed pivot couplings 6a, 6b. The pivot couplings 5a,b are configured to slide along the connecting shaft 7. In certain embodiments the central connecting shaft 7 is hollow and is in fluid communication with the compression cylinders. The compression cylinders 1,2 may be finned to increase heat dissipation.

FIG. 2 shows a cross section of the pump apparatus 100. Evident in this figure are the cylinder walls 1,2, the compression springs 4a,4b, the pivoting couplings 5a,5b that are coupled to the central shaft 7, a primary compression airspace 8, a secondary compression airspace 9, a primary piston head 10, a secondary piston head 11, an intake valve 12, a transfer valve 13, and a delivery valve 14.

The piston heads 10,11 are affixed to the central shaft 7 and the pivoting couplings 5a,5b, all of which are free to slide along their axis with respect to the frame 3a,3b and the cylinders 1,2. FIGs. 3-8 illustrate operation of the pump and the configuration that the pump components go through during compression. The first stage of compression of the gas is unconventional in that it happens as the gas transfers through the transfer conduit (e.g. central shaft 7 or a separate conduit coupled between the primary compression airspace 8 and the secondary compression airspace 9), with the compression ratio being substantially the ratio of the two comparative areas. In other words, air that resides in the primary compression airspace 8 of larger cylinder 1 is forced via the transfer conduit into the smaller cylinder 2, which is smaller in volume. For example, if the cylinders 1 and 2 differ by a factor of 2 in diameter, the compression ratio will be approximately 4. Typically, a two-stage compressor will compress air into an intermediary conduit that is of a large volume in comparison to the second cylinder 2, so 1 st stage compression happens entirely in the large cylinder 1. Air is then drawn from the intermediary volume into the second cylinder 2 for the 2nd stage of compression.

FIG. 3 shows the pistons and shaft moving to the left as depicted. The large airspace 8 fills with air through the intake valve 12 until the termination of the motion. At the end of a leftward motion, the system is in a geometric state as per FIG. 5.

FIG. 4 shows the pistons and shaft moving to the right. In particular embodiments, after filling, the large cylinder 1 transfers its charge of air through the central shaft 7 and the transfer valve 13 into the small airspace 9. In certain embodiments, a separate conduit fluidly and selectably (e.g. via a valve) coupled to airspace 8 and airspace 9 transfers compressed air from cylinder 1 to cylinder 2. This constitutes the first stage of compression as the air is forced from the large airspace 8 (i.e. larger than airspace 9) into a smaller volume of small airspace 9. At the termination of this motion, the system is in a geometric state as per FIG. 8.

There is now a pre-compressed charge of air residing within the small airspace 9 that is contained by the secondary cylinder 2 and the secondary piston head 11. As the shaft and piston heads proceed to move left, the pre-compressed air in small airspace 9 is compressed further to the delivery pressure (equilibrated with the pressure vessel through the delivery valve 14, neglecting pressure loss across the valve) and forced through the delivery valve 14 into an air storage pressure vessel. While this happens, a new charge of air is pulled into the primary airspace 8. Thus, we see asymmetric compressive action between the directions of motion: As the central shaft 7 and piston heads 10,11 move to the left, intake and delivery strokes are taking place. As the central shaft 7 and piston heads 10, 11 move to the right, the first stage of compression takes place.

FIG. 9 depicts an exemplary force profile of each stroke. In this case, 150 mm of travel and 2,000 N of maximum load are chosen, though these values can be varied greatly. The zero of the position/displacement axis is at the leftmost position, depicted in FIG. 5, and the 150 mm position is at the rightmost position, depicted in fig 8. The convention for the load is taken to be the load exerted upon the shaft by a linear actuator, with a positive sign denoting rightward force.

Line 901 depicts the first stage of compression absent of intervention by the spring. As can be seen, line 901 progresses upward in the typical fashion of compressing a gas. Line 902 depicts the second stage of compression (the negative values of the curve correspond to leftward force being exerted upon the central shaft.) Note that equilibration with tank pressure occurs about 40% of the way through the stroke, after which the load upon the piston head remains essentially constant.

Line 903 represents the force required to overcome the springs that span pivots between the frame 6a, 6b and the central shaft 5a,5b. At the leftmost position (Fig 5) the springs are still preloaded in compression and are exerting a leftward force upon the shaft. As the springs 4a, 4b move rightward towards the opposite extreme of motion, the resistive load builds to a maximum at a position shown in Fig 6. The resistive load then proceeds to fall to zero as springs reach their singularity position shown in Fig 7. At this point, both springs and their pivots are pointing

perpendicularly to the central shaft, thus proffering neither impedance nor assistance. Beyond the singularity, the springs provide assistive action to the right.

The electromechanical linear actuator that provides power to the pump apparatus 100 counters the loads due to air compression, the spring forces, and friction. Thus, curve 904 at the top of the frame, which superposes curve 903 (the spring curve) and curve 901 (1 st stage of air compression), represents the total load seen by the linear actuator as it moves from left to right. During this motion, the linear actuator is able to do more positive work up to the singularity point than it would be otherwise able of accomplishing without the spring. In addition, the average load is much higher, constituting 83% of the peak value in this direction. Curve 905 on the bottom of the frame represents the load due to the second stage of compressing the air and delivering it into the pressure vessel, plus the spring load curve. As motion happens from right to left (150 mm -> 0 mm), one sees that the initial load encountered by the actuator is higher than it would be without the spring. This is due to the additional effort of forcing the springs back to their singularity. After the singularity, however, the actuator receives massive assistance from the spring that was previously generated during the opposite stroke. This serves to keep the total load on the actuator below 2,000 N, when it would otherwise see loads of nearly 3,000 N.

The choices of relative cylinder size, spring stiffness, geometric placement of pivots, and spring preload are chosen such that curves 904 and 905 remain nearly constant in nature in their respective directions. Averaged through the stroke and combined, the curves achieve 85% of the peak load. This is in stark contrast to the 30-38% average of peak load that is seen by a double-acting single-stage pump. The result of this is two-fold. First, the normalized load seen by the linear actuator mirrors a similarly constant electric current that is required to maintain the actuator's load. This helps to maximize power usage from a power supply if given a maximum current constraint. Secondly, the disclosed invention allows more air per stroke to be delivered, when given a constraint of maximum load upon the linear actuator. As compared to a double-acting single stage air compression, the disclosed invention delivers over twice as much air per stroke given a maximum actuator load constraint.

Implementations of the subject matter and the operations described in this specification can be implemented by digital electronic circuitry, or via computer software, firmware, or hardware, including the structures disclosed in this

specification and their structural equivalents, or in combinations of one or more of them. Implementations of the subject matter described in this specification can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions, encoded on computer storage medium for execution by, or to control the operation of, data processing apparatus.

A computer storage medium can be, or be included in, a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination of one or more of them. Moreover, while a computer storage medium is not a propagated signal, a computer storage medium can be a source or destination of computer program instructions encoded in an artificially generated propagated signal. The computer storage medium can also be, or be included in, one or more separate physical components or media (e.g., multiple CDs, disks, or other storage devices).

The operations described in this specification can be implemented as operations performed by a data processing apparatus on data stored on one or more computer-readable storage devices or received from other sources. For example, particular embodiments of the invention include a linear actuator for driving the pump apparatus 100, where the linear actuator is controlled by one or more processors. The one or more processors can control the rate of linear actuation and/or the duration, for example based on one or more sensors such as pressure sensor coupled to an air storage tank or one or more of the cylinders of the pump apparatus 100.

The term "data processing apparatus" encompasses all kinds of apparatus, devices, and machines for processing data, including by way of example a programmable processor, a computer, a system on a chip, or multiple ones, or combinations, of the foregoing. The apparatus can include special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit). The apparatus can also include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, a cross-platform runtime environment, a virtual machine, or a combination of one or more of them. The apparatus and execution environment can realize various different computing model infrastructures, such as web services, distributed computing and grid computing infrastructures.

A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, obj ect, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

The processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform actions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., a FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random access memory or both. The essential elements of a computer are a processor for performing actions in accordance with instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Moreover, a computer can be embedded in another device, e.g., a mobile telephone, a personal digital assistant (PDA), a mobile audio or video player, a game console, a Global Positioning System (GPS) receiver, or a portable storage device (e.g., a universal serial bus (USB) flash drive), to name just a few. Devices suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

To provide for interaction with a user, implementations of the subject matter described in this specification can be implemented on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input. In addition, a computer can interact with a user by sending documents to and receiving documents from a device that is used by the user; for example, by sending web pages to a web browser on a user's user device in response to requests received from the web browser.

Implementations of the subject matter described in this specification can be implemented in a computing system that includes a back end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front end component, e.g., a user computer having a graphical display or a Web browser through which a user can interact with an implementation of the subject matter described in this specification, or any combination of one or more such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network ("LAN") and a wide area network ("WAN"), an inter-network (e.g., the Internet), and peer-to-peer networks (e.g., ad hoc peer-to-peer networks).

The computing system can include users and servers. A user and server are generally remote from each other and typically interact through a communication network. The relationship of user and server arises by virtue of computer programs running on the respective computers and having a user-server relationship to each other. In some implementations, a server transmits data (e.g., an HTML page) to a user device (e.g., for purposes of displaying data to and receiving user input from a user interacting with the user device). Data generated at the user device (e.g., a result of the user interaction) can be received from the user device at the server.

While this specification contains many specific implementation details, these should not be construed as limitations on the scope of any inventions or of what may be claimed, but rather as descriptions of features specific to particular

implementations of particular inventions. Certain features that are described in this specification in the context of separate implementations can also be implemented in combination in a single implementation. Conversely, various features that are described in the context of a single implementation can also be implemented in multiple implementations separately or in any suitable sub combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub combination or variation of a sub combination.

As utilized herein, the terms "approximately," "about," "substantially" and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and are considered to be within the scope of the disclosure.

It should be noted that the term "exemplary" as used herein to describe various embodiments is intended to indicate that such embodiments are possible examples, representations, and/or illustrations of possible embodiments (and such term is not intended to connote that such embodiments are necessarily extraordinary or superlative examples).

For the purpose of this disclosure, the term "coupled" means the joining of two members directly or indirectly to one another. Such joining may be stationary or moveable in nature. Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another. Such joining may be permanent in nature or may be removable or releasable in nature.

It should be noted that the orientation of various elements may differ according to other exemplary embodiments, and that such variations are intended to be encompassed by the present disclosure. It is recognized that features of the disclosed embodiments can be incorporated into other disclosed embodiments. It is important to note that the constructions and arrangements of spring systems or the components thereof as shown in the various exemplary embodiments are illustrative only. Although only a few embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter disclosed. For example, elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present disclosure.

All literature and similar material cited in this application, including, but not limited to, patents, patent applications, articles, books, treatises, and web pages, regardless of the format of such literature and similar materials, are expressly incorporated by reference in their entirety. In the event that one or more of the incorporated literature and similar materials differs from or contradicts this application, including but not limited to defined terms, term usage, describes techniques, or the like, this application controls.

While various inventive embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the inventive embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the inventive teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific inventive embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, inventive embodiments may be practiced otherwise than as specifically described and/or claimed. Inventive embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the inventive scope of the present disclosure.

Also, the technology described herein may be embodied as a method, of which at least one example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.

All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms.

The indefinite articles "a" and "an," as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean "at least one."

The phrase "and/or," as used herein in the specification and in the claims, should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with "and/or" should be construed in the same fashion, i.e., "one or more" of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the "and/or" clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to "A and/or B", when used in conjunction with open-ended language such as "comprising" can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

As used herein in the specification and/or in the claims, "or" should be understood to have the same meaning as "and/or" as defined above. For example, when separating items in a list, "or" or "and/or" shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as "only one of or "exactly one of," or, when used in the claims, "consisting of," will refer to the inclusion of exactly one element of a number or list of elements. In general, the term "or" as used herein shall only be interpreted as indicating exclusive alternatives (i.e. "one or the other but not both") when preceded by terms of exclusivity, such as "either," "one of," "only one of," or "exactly one of "Consisting essentially of," when used in the claims, shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and/or in the claims, the phrase "at least one," in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B," or, equivalently "at least one of A and/or B") can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

In the claims, and/or in the specification above, all transitional phrases such as "comprising," "including," "carrying," "having," "containing," "involving,"

"holding," "composed of," and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases "consisting of and "consisting essentially of shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent

Examining Procedures, Section 2111.03.

Any claims should not be read as limited to the described order or elements unless stated to that effect. It should be understood that various changes in form and detail may be made by one of ordinary skill in the art without departing from the spirit and scope of embodiments of the invention.

Claims

WHAT IS CLAIMED IS:

1. A pump apparatus comprising:

a frame portion;

a first compression cylinder comprising a first piston head and having a first diameter, the first compression cylinder coupled to the frame portion;

a second compression cylinder comprising a second piston head and a second diameter different than first diameter, the second compression cylinder coupled to the frame portion;

a connecting shaft coupled to the first piston head and the second piston head, the connecting shaft configured to reciprocate and to drive the first piston head and the second piston head such that an expansion of a first volume in the first compression cylinder is contemporaneous with the contraction of a second volume in the second compression cylinder as the connecting shaft is moved in a first direction and such that a contraction of the first volume in the first compression cylinder is contemporaneous with the expansion of the second volume in the second compression cylinder as the connecting shaft is moved in a second direction opposite the first direction;

an intake valve in fluid communication with the first compression cylinder to intake ambient air;

a transfer conduit for transferring compressed air from the first cylinder to the second cylinder;

a transfer valve in fluid communication with the transfer conduit to control the transfer of compressed through the transfer conduit;

an exhaust valve in fluid communication with the second compression cylinder to release compressed air from the second compression cylinder;

a first compression spring pivotally coupled to the frame portion at a first fixed pivot point and pivotally coupled to the connecting shaft at a first translating pivot point; and

a second compression spring pivotally coupled to the frame portion at a second fixed pivot point and pivotally coupled to the connecting shaft at a second translating pivot point, the first translating pivot point and the second translating pivot point configured to translate reciprocally and contemporaneously with the connecting shaft.

2. The pump apparatus according to claim 1, further comprising a linear actuator coupled to the connecting shaft configured to reciprocally drive the connecting shaft. 3. The pump apparatus according to claim 1, wherein the first compression cylinder and the second compression cylinder have differing diameters in a proportion in the range of 1.

3: 1 to 2.5: 1.

4. The pump apparatus according to claim 1, wherein the first compression spring and the second compression spring are configured to be axially aligned with one another, orthogonal to the connecting shaft, and at a maximum compression.

5. The pump apparatus according to claim 1, wherein the exhaust valve is configured to exhaust compressed air from the first compression cylinder at the maximum compression.

6. The pump apparatus according to claim 1, wherein the first compression cylinder and the second compression cylinder are coaxially aligned along the connecting shaft

7. The pump apparatus according to claim 1, wherein the connecting shaft comprises the transfer conduit.

8. The pump apparatus according to claim 1, further comprising a gas accumulator coupled to the second compression cylinder by the exhaust valve.

9. The pump apparatus according to claim 1, wherein the transfer conduit includes the transfer valve and an exhaust valve.

10. The pump apparatus according to claim 9, wherein one or more of the transfer valve, the intake valve and the exhaust valve are electronically controlled.

11. The pump apparatus according to claim 1, wherein the frame portion forms at least a portion of at least one of the first compression cylinder and the second compression cylinder.

12. The pump apparatus according to claim 1, where the first compression spring and the second compression spring have a compression spring stiffness selected such that at a maximum pumping pressure, an average driving load along a main axis of the actuator shaft is within 70% of a peak load experienced by a linear actuator coupled to the connecting shaft for reciprocally driving the connecting shaft.