Gas permeable internal floating piston

Disclosed herein is a novel gas permeable internal floating piston specifically designed for installation in the multiple stage air shock whereby the multiple stage air shock is covered in prior patent applications. The multiple stage air shock includes a mixture of oil and gas whereby the mixture provides the shock with emulsion dampening properties. The gas permeable internal floating piston operates by separating the oil from the gas thereby improving the dampening properties of the shock. The permeability of the internal floating piston is based on a membrane that allows the gas but not the oil to pass through the structure of the internal floating piston. The mechanism of the permeability is governed by the creation of a pressure differential across the structure of the internal floating piston, the creation effected with a spring. The membrane features a slow rate of permeation thereby ensuring that the internal floating piston moves in conjunction with the shaft during the operation of the shock.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application represents a novel internal floating piston that is designed exclusively for the multiple stage air shock. The multiple stage air shock is covered in U.S. patent application Ser. Nos. 13/854,055 and 14/935,423.

Not Applicable

Not Applicable

BACKGROUND OF THE INVENTION

Disclosed in patent application Ser. No. 13/854,055 is the multiple stage air shock; and, disclosed in patent application Ser. No. 14/935,423 is a process for constructing the multiple stage air shock whereby the process introduces several features including the determination of various lengths and spring rates that are absent in the art. The multiple stage air shock possesses both dampening and suspension spring capabilities whereby the dampening capability is based on an emulsion comprised of a mixture of oil and gas.

The emulsion is well known in the art and is considered to provide unpredictable dampening properties in a shock absorber, which in turn, lead to unpredictable handling characteristics for the vehicle. The deficiency of the emulsion lies in the mixing of the oil with the gas. The mixing permits the gas to alter the movement of the oil through the working piston whereby the movement of the oil through the working piston defines the dampening properties. One of the techniques used to improve the dampening properties of an emulsion based shock absorber is to prevent the oil from mixing with the gas, in effect eliminate the emulsion, which is achieved by simply separating the oil from the gas.

A common method of separating the oil from the gas is by installing an internal floating piston into the working tube of the shock absorber. The oil and gas are placed on opposing sides of the internal floating piston thereby effectively separating the oil from the gas. Such a method represents the basis for a shock absorber known as the monotube shock absorber whereby the monotube shock absorber is revered for its dampening properties. In a monotube shock absorber, the oil can be separated from the gas by attaching check valves to each end of the working tube whereby the check valve serves to add the oil and gas to the working tube. Then the oil is added via one check valve while the gas is added via the other check valve. This addition process serves to place the oil and gas on opposing sides of the internal floating piston.

Such an addition process is not realistic for the multiple stage air shock. The multiple stage air shock involves interconnecting components that serve in a manner like a working tube. However, one of the ends of one interconnecting component travels into another interconnecting component during the operation of the air shock, and therefore, is not available for receiving a check valve. A more realistic method would involve the addition of the oil and gas into the interconnecting component via a single check valve and then separating the oil from the gas in an autonomous fashion. In this case, the autonomous fashion refers to the selection of materials used in the construction of the internal floating piston. In principle, an internal floating piston that allows the gas but not the oil to pass through its structure would represent a viable means to separate the oil from the gas. This means serves as the basis for the present invention.

BRIEF SUMMARY OF THE INVENTION

The present invention offers a novel internal floating piston intended for use with the multiple stage air shock. The dampening properties of the multiple stage air shock are based on an emulsion comprised of a mixture of an oil and gas. The internal floating piston is uniquely capable of separating the oil from the gas, and in turn, changing the dampening properties of the multiple stage air shock.

The present invention also offers an internal floating piston that:

is constructed with a gas permeable membrane whereby the membrane permits the gas but not the oil to pass through the structure of the internal floating piston. This passage serves to separate the oil from the gas;

operates autonomously with the use of a spring, the spring serves to create a pressure differential across the structure of the internal floating piston whereby the pressure differential serves to induce passage of the gas through the structure thereby separating the oil from the gas;

moves in conjunction with the shaft during both compression and extension of the shaft the movement, particularly during extension, is a consequence of restricting permeation of the gas throughout the operation of the shaft, the restriction achieved by utilizing a membrane with a slow rate of permeation;

improves the dampening properties of each stage in the air shock by maintaining the separation of the oil and gas throughout the operation of each stage in the air shock;

serves to shorten the extended length, but has no effect on the spring rate, of the air shock.

DETAILED DESCRIPTION OF THE INVENTION

Described below is a gas permeable internal floating piston specifically designed for installation in the multiple stage air shock. The multiple stage air shock is disclosed in patent application Ser. No. 13/854,055 whereby a process for constructing the multiple stage air shock is disclosed in patent application Ser. No. 14/935,423. The internal floating piston features a gas permeable membrane that has a slow rate of permeation the permeability serves to separate the oil from the gas while the slow rate of permeation permits the internal floating piston to move in conjunction with the shaft during the operation of the air shock. To facilitate understanding of the present invention, the multiple stage air shock is described; and then exemplified with the four stage air shock.

Referring toFIGS. 1-4, the internal floating piston10is illustrated in detail. The internal floating piston10has a composite construction that includes a cup11and gas permeable membrane12. The cup11is made from metal alloy or plastic with a solid wall, porous bottom with inner and outer sides11aand11b, and is able to be associated with a spring13. The wall represents a cylindrical surface that facilitates the sliding motion of the internal floating piston10within the space of the working tube or dual function shaft in the same manner as does the working piston. The cylindrical surface and porous bottom give the internal floating piston10the structure of a porous cup whereby the structure gives the internal floating piston10a thickness ip. The inner bottom of the cup11refers to the inner side11aof the internal floating piston10while the outer bottom of the cup11refers to the outer side11bof the internal floating piston10. The membrane12is attached to the outer side11bof the internal floating piston10and is permeable to gases but not liquids. The porous bottom of the cup11cooperates with the permeable membrane12such that the internal floating piston10is permeable to the gas but not the oil whereby the internal floating piston10being permeable to the gas indicates that the gas is able to pass through the structure of the internal floating piston10. The permeation mechanism is adsorption of the gas into the membrane12, diffusion of the gas across the membrane12, and desorption of the gas from the membrane12. The permeation of the gas across the membrane12defines the permeation of the gas through the structure of the internal floating piston10and is governed by the presence of a pressure differential across the inner and outer sides11aand11bof the internal floating piston10. The spring13is constructed from steel wire and has short and long ends whereby the short end is attached to the inner side11aof the internal floating piston10while the long end is able to be butted up against the closed end of the working tube or dual function shaft.

Referring toFIGS. 5-14, there is shown the installation of the internal floating piston10in a stage. The stage refers to the fundamental shock unit in the multiple stage air shock. The multiple stage air shock includes a working tube and two or more shafts, working pistons, and end caps. The stage consists of the one and second interconnected components whereby the one component is the dual or single function shaft16or17while the second component is the working tube15or dual function shaft16.

The working tube15has the one and second ends whereby the one end is closed and the second end is open such that the closed end is attached to a mounting eyelet while the open end is attached to the end cap19. The end cap19serves as a seal in a manner like a torus gasket.

The one or second component is able to define a shaft and has the one and second ends whereby the type of the shaft is defined by the type of the ends the shaft has: the one end is closed and the second end is either closed or open. The one end is attached to the working piston18. When the second end is closed, the second end is attached to the mounting eyelet and the one component is a single function shaft17; whereas when the second end is open, the second end is attached to the end cap19and the one or second component is a dual function shaft16.

The working piston18has a disk and shims whereby the disk contains a large hole in the center and smaller surrounding holes. The center hole permits the working piston18to be attached to the one component. The shims have varying holes, diameters, and thicknesses whereby the shims are arranged sequentially on each side of the disk.

The interconnection between the one and second components refers to the one closed end of the one component being slidably inserted into the open end of the second component whereby the one component sliding into or out of the second component refers to the one component being compressed or extended, and thereby refers to the stage being compressed or extended, respectively. The compression or extension of the stage refers to the operation of the stage and is caused by suspension forces acting on the stage. The insertion defines a space within the second component whereby the space is between the closed end and end cap19, has a volume, and refers to a volume of the stage. The end cap19is equipped with a check valve20whereby the check valve20permits oil and gas to be added to or removed from the stage. The addition of a given amount of oil or gas refers to the oil or gas charge, respectively. The oil and gas occupy the space such that the sealing action of the end cap19confines the oil and gas to the space whereby the confinement allows the oil to have a volume and gas to have both a volume and pressure. The gas pressure is related to the gas charge and defines a force whereby the force is able to be a suspension spring force. The suspension spring force provides the stage with a suspension spring capability thereby enabling the stage both to support part of the weight of the vehicle and to react to suspension movements.

Assembling the stage involves: first, the internal floating piston10is slidably inserted into the open end of the second component thereby the internal floating piston10is enabled to slide within the second component under guidance by the solid wall of the internal floating piston10whereby the long end of the spring13is butted up against the closed end of the second component; and second, the one component is slidably inserted into the open end of the second component whereby the one and second components are able to belong to one and another stages, respectively. The internal floating piston10divides the space within the second component into the one and second cells21and22, respectively, such that the one cell21is between the outer side11bof the internal floating piston10and end cap19while the second cell22is between the inner side11aof the internal floating piston10and closed end23of the second component whereby the spring13is located in the second cell22. The space has a volume such that the volume defines the volumes of the one and second cells21and22, the volumes of the one and second cells21and22refers to the volume of the stage.

Referring toFIGS. 9 and 10, during the operation of the stage both the internal floating piston10and one component move in the same direction such that during compression, the internal floating piston10slides towards the closed end of the second component while the one component slides into the second component; whereas during extension the internal floating piston10slides away from the closed end of the second component while the one component slides out of the second component. Referring toFIGS. 11 and 12, the dimensions of the stage are shown including: diameter and length of the second component DWand LW, diameter and length of the one component DSand LWS, shaft stroke LS, and thicknesses of the internal floating piston ip, working piston wp, shaft shoulder ss, end cap ec, and mounting eyelet me, respectively.

Referring toFIGS. 15 and 16, there is shown the mechanism of dampening by the working piston18, in this case emphasizing the process of charging a stage with oil and gas. For purposes of discussion: (1) the stage comprises the shaft S and component C whereby the shaft S refers to the dual or single function shaft16or17while the component C refers to the working tube15or dual function shaft16; and (2) the working piston18has a disk24and shims25and26, and is located between the fastener27and shaft shoulder28whereby the fastener27attaches the working piston18to the shaft S. The shims25and26are arranged sequentially on each side of the disk24such that the shims25are located next to the fastener27while the shims26are located next to the shaft shoulder28.

Since the working piston18is attached to the shaft S, the working piston18moves in concert with the shaft S as the shaft S slides into or out of the component C: referring toFIG. 15, the dashed arrows show that the working piston18is sliding into the component C thereby indicating that the stage is undergoing compression; while referring toFIG. 16, the dashed arrows show that the working piston18is sliding out of the component C thereby indicating that the stage is undergoing extension. The motion of the working piston18causes the oil to flow through the holes in the disk24and shims25and26: referring toFIG. 15, the shaded dotted line boxes define the holes in the disk24and shims25and26. The solid arrows show that: during compression, the oil flows into the holes in the shims25, through the holes in the disk24, and out of the holes in the shims26, and then into the passageway29between the shaft S and cylinder wall of the component C; while during extension, the oil flows out of the passageway29between the shaft S and cylinder wall of the component C and into the holes in the shims26, through the holes in the disk24, and out of the holes in the shims25.

The flow of the oil through the holes causes the working piston18to resist the sliding of the shaft S whereby the resistance acts to dampen the suspension spring motion of the stage. The suspension spring motion of the stage refers to the suspension spring capability of the stage whereby the suspension spring capability of the stage is provided by the gas pressure. The emulsion that results from the mixing of the oil and gas is known to cause the dampening ability of the working piston to vary unpredictably whereby the unpredictable dampening results in unpredictable handling for the vehicle. The installation of the internal floating piston10into the component Coffers the ability to separate the oil from the gas in the component C whereby this separation prevents the mixing of the oil and gas and leads to predictable dampening. Predictable dampening leads to predictable reactions by the shock to suspension forces which in turn results in predictable handling for the vehicle.

Referring toFIG. 17, there is shown a representation of a common monotube shock that is comprised of one working tube15, single function shaft17, and internal floating piston10. The oil can be easily separated from the gas by utilizing one and a second check valves20aand20b—the one check valve20ais mounted to the closed end23of the working tube15while the second check valve20bis mounted to end cap19. The one check valve20ais used only for adding the oil while the second check valve20bis used only for adding the gas. Since the internal floating piston10is located within the space between the closed end23of the working tube15and end cap19, this method of addition naturally leads to the oil occupying the one cell21between the end cap19and internal floating piston10while the gas occupies the second cell22between the closed end of the working tube15and internal floating piston10.

Referring toFIG. 18, there is shown a four stage air shock in which each stage is fully compressed; each stage is equipped with the internal floating piston10. The closed end23of each dual function shaft16is inserted into the interconnecting component and therefore is not available for receiving a check valve20. Since each end cap19remains outside the interconnecting component at all times during the operation of each stage, then only the end cap19is able to receive a check valve20. Both the oil and gas must be added to each stage via the check valve20that is mounted to each end cap19. A logical alternative would require some type of channel to be machined within the cylinder wall of each dual function shaft16from each end cap19to the closed end23of each dual function shaft16. The interconnecting component refers to the working tube15or dual function shaft16.

Referring toFIG. 19, there is shown a close-up view of a stage that comprises a dual function shaft16and shaft S, in this case emphasizing both a shaded channel30that is machined into the cylinder wall of the dual function shaft16and a shaded channel31that is machined into the end cap19. One and a second check valves20aand20bare mounted to the end cap19. The channel30connects a hole in the closed end23of the dual function shaft16to the one check value20awhile the channel31connects a hole in the end cap19to the second check value20b. The one check valve20avents to the second cell22because the one check valve20ais connected to the second cell22via the channel30that is machined into the cylinder wall of the dual function shaft16; while the second check valve20bvents to the one cell21because the second check valve20bis connected to the one cell21via the channel31that is machined into the end cap19.

Cooperation between the channel31and second check valve20brepresents the normal means by which oil and gas are added to or removed from the space within a stage in the multiple stage air shock. The oil would be added via the second check valve20bin the normal manner into the one cell21thereby locating the oil between the end cap19and internal floating piston10. Meanwhile the gas could be added via the one check valve20aand channel30into the second cell22thereby locating the gas between the closed end23of the dual function shaft16and internal floating piston10. The additions serve to locate the oil and gas on opposite side of the internal floating piston10and thereby separate the oil from the gas. However, the process of machining a channel30within the wall of a thin-walled cylinder is not realistic. As a practical matter, both the oil and gas must be added via the second check valve20b. Following the addition of the oil and gas, the oil must be separated from the gas autonomously within the space of the stage. The present invention suggests three different methods of effecting this autonomous separation whereby this autonomous separation refers to the operation of the internal floating piston10.

Note: referring toFIG. 18, in the four stage air shock the working tube15could be equipped with another check valve at the closed end23in addition to the check valve20that is attached to the end cap19; and therefore, oil and gas can be separated as discussed for the common monotube shock. For purposes of discussion, the working tube15is treated in the same manner as each dual function shaft16.

Referring toFIGS. 20-36, there is shown the stage that is equipped with the internal floating piston10, in this case emphasizing the process of the internal floating piston10separating the oil and gas into the one and second cells, respectively. For purposes of discussion: (1) the dual function shaft16and single function shaft17and are referred to as the component16and shaft17, respectively, whereby the component16refers to the working tube15or dual function shaft16while the shaft17refers to the dual function shaft16or single function shaft17, (2) referring toFIG. 20, the stage is oriented right side up whereby the stage is in a vertical position such that the closed end23of the component16is at the top of the space while the end cap19of the component16is at the bottom of the space whereby the one cell21is below the internal floating piston10while the second cell22is above the internal floating piston10; and, referring toFIG. 21, the stage is oriented upside down whereby upside down is the opposite of right side up, and (3) the internal floating piston10is not attached to the spring13except as noted in method 3 below. The space within the component16contains the internal floating piston10whereby the internal floating piston10divides the space into the one and second cells21and22. The oil and gas are able to occupy opposite sides of the internal floating piston10such that the oil occupies the one cell21while the gas occupies the second cell22. The process of separating the oil and gas into the one and second cells21and22involves two steps: in step one, the stage is charged with oil and gas such that both the oil and gas occupy the one cell21; and in step two, the gas permeable membrane12is utilized in conjunction with a pressure differential. The membrane12allows the gas but not oil to pass through the structure of the internal floating piston10while the creation of a pressure differential across the sides of the internal floating piston10serves as the force that induces a net flow of gas through the structure of the internal floating piston10from the one cell21into the second cell22.

The pressure differential can be created with at least three methods: the process of charging the stage with oil and gas in methods 1 and 2 is different than that for method 3, therefore step one for methods 1 and 2 is discussed separately from that for method 3.

Step One for methods 1 and 2: Referring toFIG. 22, the stage is oriented upside down such that the end cap19of the component16is at the top of the space while the closed end23of the component16is at the bottom of the space. The shaft17is fully compressed such that the working piston18pushes the internal floating piston10against the closed end23whereby the space within the component16consists of the one cell21only. The stage is charged with oil and gas through the check valve20that is located on the end cap19: first the oil charge is added thereby filling up the one cell21whereby a small amount of air occupies the cup11in the structure of the internal floating piston10and is ignored; second referring toFIG. 23, the gas charge is added whereby the shaft17fully extends to accommodate the gas, and the space within the component16consists of the one cell21only whereby the one cell21is positioned above the internal floating piston10while the internal floating piston10is still bottomed out against the closed end23of the component16. Since the oil and gas are immiscible, the oil does not mix with the gas and since the oil and gas occupy the one cell21, the oil locates next to the gas such that the surface of the oil contacts that of the gas whereby the contacting surfaces are defined as the interface. The locations of the oil and gas at the interface are defined by density such that the more dense oil will locate below the interface next to the internal floating piston10while the less dense gas will locate above the interface next to the end cap19. After addition of the gas charge, the stage is rotated 180 degrees to the right side up orientation such that the closed end23of the component16is at the top of the space while the end cap19of the component16is at the bottom of the space; the one cell21is below the internal floating piston10such that the oil will locate below the interface next to the end cap19while the gas will locate above the interface next to the internal floating piston10. For method 1; referring toFIG. 24, the internal floating piston10is heavy enough that it slides downward in the space within the component16, the force of gravity FVacting to pull the internal floating piston10downward against the gas. For method 2; referring toFIG. 25, the working piston18and internal floating piston10are constructed in a manner such that they possess strong permanent magnetic properties. Upon insertion into the space within the component16, the internal floating piston10is positioned such that it is magnetically attracted to the working piston18. Slow compression of the shaft17either by mechanical means or by installing the shock on a vehicle and cycling the suspension through its range of travel will act locate the working piston18close to the internal floating piston10, the close proximity between the working piston18and internal floating piston10serves to create a strong attractive magnetic interaction between the working piston18and internal floating piston10, the interaction between the working piston18and internal floating piston10causes a magnetic force FMthat acts to pull the internal floating piston10downward against the gas.

Step One for method 3: the short end of the spring13is attached to the inner side11aof the internal floating piston10and then the internal floating piston10is inserted into the component16such that the long end of the spring13is butted against the closed end23of the component16. Referring toFIG. 26, the stage is oriented upside down such that the end cap19of the component16is at the top of the space while the closed end23of the component16is at the bottom of the space, and the shaft17is fully compressed such that the internal floating piston10bottoms out against the closed end23of the component16, the location of the internal floating piston10serves to fully compress the spring13. Referring toFIG. 27, gas is added such that the shaft17fully extends whereby fully compressing the stage and then adding gas serves to purge the space within the component16of the moisture that is in the air; the small amount of air occupying the cup11of the internal floating piston10is not purged and is ignored. The process of fully extending the shaft17allows the spring13that is attached to the internal floating piston10to also fully extend whereby the gas, at atmospheric pressure, occupies both the one and second cells21and22, respectively. Referring toFIG. 28, the component16is charged with oil whereby the fully extended spring13positions the internal floating piston10in a manner such that the addition of the oil charge acts to fill up the one cell21whereby the gas in the second cell22is at atmospheric pressure.

Referring toFIGS. 29 and 30, the component16is charged with gas whereby the more dense oil will locate below the interface next to the internal floating piston10while the less dense gas charge will locate above the interface next to the end cap19, the one cell21now contains both the oil and gas charges. The pressure of the gas charge exerts a force on the oil whereby the oil is non-compressible while the internal floating piston10is impermeable to the oil thereby enabling the oil to transfer the force against the internal floating piston10. The pressure of the gas charge is greater than atmospheric pressure while the force of the gas pressure is greater than that of the spring thereby enabling the force of the gas pressure to cause the internal floating piston10to slide downward, the downward motion of the internal floating piston10compresses the spring13, decreases the volume of the second cell22, and increases the pressure of the gas in the second cell22; the downward motion continues until the pressure of the gas in the second cell22is the same as that of the gas charge. Since the density of the gas is less than that of the oil, the gas in the second cell22will exert a force FUPthat acts upward against the internal floating piston10. Since the internal floating piston10is permeable to the gas, the upward force FUPdefines an increase in pressure next to the inner side11aof the internal floating piston10while there is no change in pressure next to the outer side11bof the internal floating piston10. The pressure imbalance defines a pressure differential across the structure of the internal floating piston10whereby the pressure differential induces a net flow of gas GFthrough the structure of the internal floating piston10from the second cell22and into the one cell21. As soon as the gas from the second cell22passes through the internal floating piston10into the one cell21, the gas is able to bubble upward through the oil and accumulate with the gas charge that is next to the end cap19whereby the gas from the second cell22and gas charge are hereafter referred to as the gas. The combination of the flow of the gas GFthrough the structure and the force of the gas pressure being greater than that of the spring13causes the internal floating piston10to continue sliding downward until the internal floating piston10bottoms out against the closed end23of the component16. The force of the gas pressure holds the internal floating piston10against the closed end23of the component16whereby the location of the internal floating piston10fully compresses the spring13. The space within the component16consists of the one cell21only.

Note: After the oil charge is added but before the gas charge is added, the oil is heavier than the gas that is in the second cell22thereby resulting in a difference in density between the oil and gas. This difference in density will allow the gas to exert a force that acts upward against the internal floating piston10. Since the internal floating piston10is permeable to the gas, the upward force will serve to create a pressure differential across the sides of the internal floating piston10such that the gas is induced to flow through the structure of the internal floating piston10from the second cell22and into the one cell21. However, this flow of gas is ignored because the force associated with the difference in density is insufficient to compress the spring13. The spring13would necessarily have to be compressed in order to account for the increase in volume of the one cell21and equivalent decrease in volume of the second cell22that would result from the flow of gas through the structure of the internal floating piston10. In particular, the downward motion of the internal floating piston10only compresses the spring13and does not create a pressure differential that induces the flow of gas GFthrough the structure of the internal floating piston10from the second cell22and into the one cell21. The force of the gas pressure that causes the downward motion of the internal floating piston10is due to the gas pressure next to the outer side11bbeing greater than that next to the inner side11awhich is opposite the increase in pressure next to the inner side11awith no change in pressure next to the outer side11b. The increase in pressure next to the inner side11awith no change in pressure next to the outer side11bdefines the pressure differential that serves to induce the flow of gas GFthrough the structure of the internal floating piston10from the second cell22and into the one cell21.

Referring toFIG. 31, the stage is rotated 180 degrees to the right side up orientation such that the closed end23of the component16is at the top of the space while the end cap19of the component16is at the bottom of the space whereby the more dense oil is below the interface next to the end cap19while the less dense gas is above the interface next to the internal floating piston10. Since the internal floating piston10is permeable to the gas, the gas is able to flow through the internal floating piston10. The ability to flow indicates that the force of the gas pressure is able to have no effect on the internal floating piston10, and instead acts against the closed end of the component16. The absence of the effect cancels the force of the gas pressure against the internal floating piston10; therefore the internal floating piston10is no longer held against the closed end23of the component16. Since the internal floating piston10is no longer held against the closed end23of the component16, the spring13that is attached to the internal floating piston10begins to extend exerting the force FSPagainst the internal floating piston10such that the internal floating piston10pushes downward against the gas.

Step Two: Referring toFIG. 32for methods 1 and 2, andFIG. 33for method 3, the downward motion MDof the internal floating piston10creates a greater pressure zone next to the outer side11bof the internal floating piston10while an equivalent lower pressure zone is created next to the inner side11aof the internal floating piston10. Again the pressure imbalance defines the pressure differential across the structure of the internal floating piston10, the pressure differential induces the net flow of gas GFthrough the structure of the internal floating piston10from the one cell21and into the second cell22such that the oil occupies the one cell21and the gas occupies the second cell22.

Referring toFIGS. 34 and 35, the forces FVand FMcreated by gravity and magnetism in methods 1 and 2 and the fully extended spring13in method 3 will serve to constantly hold the internal floating piston10at the interface; in particular the forces FVand FMcreated in methods 1 and 2 are constantly exerted on the internal floating piston10and in turn the internal floating piston10transfers the forces FVand FMagainst the oil, respectively. Referring toFIG. 36, since both the shaft17and spring13that is attached to the internal floating piston10are fully extended when the one cell21is filled up with oil and since the oil is non-compressible, then any force that acts to compress the shaft17from full extension will also serve to compress the spring13; in effect anytime the shaft17is not in the fully extended position, the spring13will be compressed, and therefore, will exert a force FSPagainst the internal floating piston10and in turn the internal floating piston10transfers the force FSPagainst the oil. Since the downward forces FV, FM, and FSPare constantly acting against the oil, then so long as the stage is oriented right side up the more dense oil will remain below the interface in the one cell21and the less dense gas will remain above the interface in the second cell22while the internal floating piston10remains at the interface and maintains separation of the oil and gas, regardless of the stroke of the shaft17or pressure of the gas.

While the methods 1-3 are each capable of maintaining separation of the oil and gas during the operation of the stage, the present invention focuses on the method 3. Henceforth, all subject matter is based on the principles discussed in method 3.

Referring toFIGS. 37-45, there are shown the stage that is equipped with the internal floating piston10, in this case emphasizing the motion of the internal floating piston10during the operation of the stage. For purposes of discussion, (1) the single function shaft17is called a shaft17and refers to the dual or single function shaft while the dual function shaft16is called a component16and refers to the working tube or dual function shaft, (2) road obstructions define suspension forces that are exerted on the stage while the gas pressure defines a force that counteracts the suspension force, and (3) the volume of the gas G occupying the cup of the internal floating piston10is ignored:

Referring toFIGS. 37-40, there is shown the stage undergoing compression. During the operation of the stage, suspension forces are exerted on the stage thereby causing the stage to compress; whereas when the suspension forces are reduced, the force of the gas pressure counteracts the suspension force and causes the stage to extend: (1) during compression, suspension forces are exerted on the stage thereby causing the shaft17to slide into the component16. The suspension forces that are exerted on the shaft17are transferred to the oil. Since the internal floating piston10is not permeable to the oil, then the suspension forces that are exerted on the oil are transferred to the internal floating piston10thereby causing the internal floating piston10to slide towards the closed end of the component16. The motion of the internal floating piston10decreases the volume of the second cell whereby the decrease in the volume serves to increase the gas pressure; (2) during extension, the suspension forces exerted on the stage are reduced, in turn, the suspension forces exerted on the shaft17are reduced, in turn, the suspension forces that are transferred to the oil are reduced, in turn, the suspension forces that are transferred to the internal floating piston10are reduced. Since the internal floating piston10is permeable to the gas but not the oil, then in principle the gas is able to flow through the internal floating piston10. The ability to flow indicates that the force of the gas pressure is able to have no effect on the internal floating piston10. The absence of the effect indicates that the force of the gas pressure does not act on the internal floating piston10, and instead the gas pressure exerts a force directly on the oil; this way when the suspension forces that are transferred to the internal floating piston10are reduced, the force of the gas pressure that is exerted on the oil is transferred to the shaft17thereby causing the shaft17to slide out of the component16.

During extension, the shaft17slides out of the component16and away from the internal floating piston10. In principle, the motion of the shaft17serves to create a low pressure zone next to the outer side11bof the internal floating piston10while the gas pressure serves to create a high pressure zone next to the inner side11aof the internal floating piston10. The resulting pressure differential induces a net flow of gas through the structure of the internal floating piston10from the second cell and into the one cell. Since the motion of the shaft17is able to be very rapid, then the internal floating piston10must also be able to move very rapidly in conjunction with the shaft17in order for the internal floating piston10to remain at the interface and maintain separation of the oil and gas. Such rapid motion by the internal floating piston10can be realized by utilizing a membrane12that possesses a slow permeation rate. During the rapid extension of the shaft17, the slow permeation rate indicates that the gas is able to remain in the second cell such that the pressure of that gas is able to exert a force against the internal floating piston10thereby causing the internal floating piston10to move while very little, if any, of the gas will permeate across the internal floating piston10. In reaction to suspension forces, the movement of the shaft17can occur on the order of fractions of a second while the slow permeation rate of the gas occurs on the order of minutes. During the operation of the stage, the shaft17can undergo numerous of cycles of compression and extension within a minute. For example, assume one cycle occurs every second while the gas permeates across the internal floating piston10in 5 minutes then: (a) in one minute the shaft17will have cycled 60 times while only 20% of the gas will be able to permeate across the internal floating piston10(b) in three seconds, the shaft17will have cycled 3 times while only 1% of the gas will be able to permeate across the internal floating piston10and (c) in one second during any given cycle at least 99% of the gas will remain in the second cell such that the pressure of that gas will exert a force against the internal floating piston10thereby causing the internal floating piston10to move while at most 1% of the gas will be able to permeate across the internal floating piston10. Moreover only 50% of those cycles, i.e., the extension movements, require the slow permeation rate of the membrane12to keep the gas in the second cell because the remaining 50% of those cycles, i.e., the compression movements, will serve to push the internal floating piston10against the spring13, in turn, the spring13compresses thereby creating the pressure differential that serves to induce the net flow of gas through the internal floating piston10from the one cell and into the second cell. In effect, once the internal floating piston10separates the oil and gas such that they occupy the one and second cells, then the oil and gas will remain separated by the internal floating piston10during the operation of the stage.

As a practical matter, during extension the force of the gas pressure is exerted on the internal floating piston10rather than directly on the oil. Therefore the force of the gas pressure that is exerted on the internal floating piston10is transferred to the oil, in turn, the force of the gas pressure that is exerted on the oil is transferred to the shaft17thereby causing the shaft17to slide out of the component16. The slow permeation rate of the membrane12ensures that the oil and gas remain separated and occupy the one and second cells, respectively, thereby ensuring that the force of the gas pressure is exerted on the internal floating piston10such that the internal floating piston10rapidly slides away from the closed end of the component16and moves in conjunction with the shaft17.

The motion of the shaft17causes a change in the volume of the space within the component16, the volume of the space define the volumes of the one and second cells while the one and second cells define the volume of the stage. Since the oil occupies the one cell and is non-compressible, then the volume of the one cell remains constant; and, results in the change in the volume of the space within the component16referring to the change in the volume of the second cell ΔVIFP, i.e., the change in the volume of the space within the component16is the same as the change in the volume of the second cell ΔVIFP. Therefore, the change in the volume of the second cell ΔVIFPdefines the change in the volume of the stage. Since the gas occupies the second cell, then the change in the volume of the space within the component16refers to the change in the volume of the gas ΔVGwhereby the change in the volume of the gas ΔVGis the same as the change in the volume of the second cell ΔVIFP. Since the motion of the shaft17causes the change in the volume of the space within the component16, then the change in the volume of the shaft stroke ΔVSrefers to the change in the volume of the space within the component16. In summary, the change in the volume of the shaft stroke ΔVSdefines the change in the volume of the space within the component16, the change in the volume within the component16refers to the change in the volume of the second cell ΔVIFP, the change in the volume of the second cell ΔVIFPrefers to the change in the volume of the gas ΔVG—in short, the change in the volume of the shaft stroke ΔVSdefines the change in the volume of the gas ΔVG. Since the change in the volume of the second cell ΔVIFPdefines the change in the volume of the stage, then the change in the volume of the gas ΔVGdefines the change in the volume of the stage.

During the motion of the shaft17, the working piston18and internal floating piston10are displaced. Referring toFIG. 37; starting with the stage at full extension, then the origins of the displacements are shown as the right-hand side rWPand rIFPof the working piston18and internal floating piston10, respectively. The displacements dWPand dIFPof the working piston18and internal floating piston10are different, respectively: since the working piston18is attached to the shaft17, then the displacement dWPof the working piston18is the same as the change in the shaft stroke ΔLS. In contrast, the displacement dIFPof the internal floating piston10is less than the displacement dWPof the working piston18; the difference being due to part of the oil flowing into or out of the passageway29between the shaft17and cylinder wall of the component16. Referring toFIGS. 37-40, as the stage undergoes compression, part of the oil flows into the passageway29between the shaft17and cylinder wall of the component16whereby this flow reduces the amount of oil between the working piston18and internal floating piston10—in effect the working piston18gets closer to the internal floating piston10. Since the working piston18gets closer to the internal floating piston10, then the internal floating piston10is moving slower than the working piston18and thereby the displacement dIFPof the internal floating piston10is less than the displacement dWPof the working piston18.

Referring toFIGS. 41-45, there is shown a set of equations used to find the relative displacements dWPand dIFPof the working piston18and internal floating piston10, respectively. Since the change in the volume of the second cell ΔVIFPrefers to the change in the volume of the shaft stroke ΔVS, then the relationship between the change in the volume of the second cell VIFPand that of the shaft stroke VScan be used to describe the relationship between the displacement dIFPof the internal floating piston10and displacement dWPof the working piston18. Referring toFIG. 45, the set of equations is used to derive an algorithm that shows that the displacement dIFPof the internal floating piston10is less than the displacement dWPof the working piston18.

In principle, the volume of the gas VGis the sum of the volume of the shaft stroke VSplus the volume of the gas G occupying the cup of the internal floating piston10. For purposes of discussion, the volume of the gas G occupying the cup is ignored; therefore, the volume of the gas VGis the same as the volume of the shaft stroke VS. As a practical matter, the difference between the volume of the shaft stroke VSand that of the gas VGthat is caused by the volume of the gas G occupying the cup has negligible effect on computations regarding gas pressure particularly those involving spring rate and therefore this difference is ignored.

Referring toFIGS. 46-51, there is shown the four stage air shock in various states of operation, in this case emphasizing the installation of the internal floating piston into each stage of the four stage air shock:

The first stage includes the working tube32, first dual function shaft33, and first internal floating piston45. The working tube32has a closed end and an open end whereby the closed end is affixed to a mounting eyelet while the open end is attached to a first end cap41. The first dual function shaft33has a closed end and an open end whereby the closed end is attached to a first working piston37while the open end is attached to a second end cap42. The first internal floating piston45has the structure of a porous cup whereby the structure comprises a solid wall, inner and outer sides, and a first spring49; and, the first spring49has a short and long ends whereby the short end is attached to the inner side. The first internal floating piston45is slidably inserted into the open end of the working tube32thereby the first internal floating piston45is enabled to slide within the working tube32under guidance by the solid wall whereby the long end of the first spring49is butted up against the closed end of the working tube32; then, the first dual function shaft33is slidably inserted into the open end of the working tube32. The process of the first dual function shaft33being inserted into the working tube32defines a space within the working tube32between the closed end of the working tube32and first end cap41; whereas, the first internal floating piston45divides the space into the one and second cells whereby the one cell is between the outer side of the first internal floating piston45and first end cap41while the second cell is between the inner side of the first internal floating piston45and closed end of the working tube32. The space has a volume VWwhich defines the volumes of the one and second cells whereby the volumes of the one and second cells define the volume VWof the first stage. The first end cap41is equipped with a check valve20, the check valve20serves as a means to add oil and gas to or remove oil and gas from the first stage. The first internal floating piston45has a gas permeable membrane whereby the membrane is attached to the outer side of the first internal floating piston45and is permeable to gases but not liquids. The permeability allows the gas but not the oil to pass through the structure thereby the first internal floating piston45is able to separate the oil and gas such that the oil is able to occupy the one cell while the gas is able to occupy the second cell. The first end cap41acts as a seal such that the oil and gas are confined to the one and second cells; and the confinement allows the oil to have a volume and gas to have both a volume and pressure whereby the gas pressure defines a force.

The second stage includes the first dual function shaft33, second dual function shaft34, and second internal floating piston46. The second dual function shaft34has a closed end and an open end whereby the closed end is attached to a second working piston38while the open end is attached to a third end cap43. The second internal floating piston46has the structure of a porous cup whereby the structure comprises a solid wall, inner and outer sides, and a second spring50; and, the second spring50has a short and long ends whereby the short end is attached to the inner side. The second internal floating piston46is slidably inserted into the first dual function shaft33thereby the second internal floating piston46is enabled to slide within the first dual function shaft33under guidance by the solid wall whereby the long end of the second spring50is butted up against the closed end of the first dual function shaft33; then the second dual function shaft34is slidably inserted into the first dual function shaft33. The process of the second dual function shaft34being inserted into the first dual function shaft33defines a space within the first dual function shaft33between the closed end of the first dual function shaft33and second end cap42; whereas, the second internal floating piston46divides the space into the one and second cells whereby the one cell is between the outer side of the second internal floating piston46and second end cap42while the second cell is between the inner side of the second internal floating piston46and closed end of the first dual function shaft33. The space has a volume VW1which defines the volumes of the one and second cells whereby the volumes of the one and second cells define the volume VW1of the second stage. The second end cap42is equipped with a check valve20, the check valve20serves as a means to add oil and gas to or remove oil and gas from the second stage. The second internal floating piston46has a gas permeable membrane whereby the membrane is attached to the outer side of the second internal floating piston46and is permeable to gases but not liquids. The permeability allows the gas but not the oil to pass through the structure thereby the second internal floating piston46is able to separate the oil and gas such that the oil is able to occupy the one cell while the gas is able to occupy the second cell. The second end cap42acts as a seal such that the oil and gas are confined to the one and second cells; and the confinement allows the oil to have a volume and gas to have both a volume and pressure whereby the gas pressure defines a force.

The third stage includes the second dual function shaft34, third dual function shaft35, and third internal floating piston47. The third dual function shaft35has a closed end and an open end whereby the closed end is attached to a third working piston39while the open end is attached to a fourth end cap44. The third internal floating piston47has the structure of a porous cup whereby the structure comprises a solid wall, inner and outer sides, and a third spring51; and, the third spring51has a short and long ends whereby the short end is attached to the inner side. The third internal floating piston47is slidably inserted into the second dual function shaft34thereby the third internal floating piston47is enabled to slide within the second dual function shaft34under guidance by the solid wall whereby the long end of the third spring51is butted up against the closed end of the second dual function shaft34; then the closed end of the third dual function shaft35is slidably inserted into the second dual function shaft34. The process of the third dual function shaft35being inserted into the second dual function shaft34defines a space within the second dual function shaft34between the closed end of the second dual function shaft34and third end cap43; whereas, the third internal floating piston47divides the space into the one and second cells whereby the one cell is between the outer side of the third internal floating piston47and third end cap43while the second cell is between the inner side of the third internal floating piston47and closed end of the second dual function shaft34. The space has a volume VW2which defines the volumes of the one and second cells whereby the volumes of the one and second cells define the volume VW2of the third stage. The third end cap43is equipped with a check valve20, the check valve20serves as a means to add oil and gas to or remove oil and gas from the third stage. The third internal floating piston47has a gas permeable membrane whereby the membrane is attached to the outer side of the third internal floating piston47and is permeable to gases but not liquids. The permeability allows the gas but not the oil to pass through the structure thereby the third internal floating piston47is able to separate the oil and gas such that the oil is able to occupy the one cell while the gas is able to occupy the second cell. The third end cap43acts as a seal such that the oil and gas are confined to the one and second cells; and the confinement allows the oil to have a volume and gas to have both a volume and pressure whereby the gas pressure defines a force.

The fourth stage includes the third dual function shaft35, single function shaft36, and fourth internal floating piston48. The single function shaft36has the one and second closed ends whereby the one closed end is attached to a fourth working piston40while the second closed end is affixed to a mounting eyelet. The fourth internal floating piston48has the structure of a porous cup whereby the structure comprises a solid wall, inner and outer sides, and a fourth spring52; and, the fourth spring52has a short and long ends whereby the short end is attached to the inner side. The fourth internal floating piston48is slidably inserted into the third dual function shaft35thereby the fourth internal floating piston48is enabled to slide within the third dual function shaft35under guidance by the solid wall whereby the long end of the fourth spring52is butted up against the closed end of the third dual function shaft35; then the single function shaft36is slidably inserted into the third dual function shaft35. The process of the single function shaft36being inserted into the third dual function shaft35defines a space within the third dual function shaft35between the closed end of the third dual function shaft35and fourth end cap44; whereas, the fourth internal floating piston48divides the space into the one and second cells whereby the one cell is between the outer side of the fourth internal floating piston48and fourth end cap44while the second cell is between the inner side of the fourth internal floating piston48and closed end of the third dual function shaft35. The space has a volume VW3which defines the volumes of the one and second cells whereby the volumes of the one and second cells define the volume VW3of the fourth stage. The fourth end cap44is equipped with a check valve20, the check valve20serves as a means to add oil and gas to or remove oil and gas from the fourth stage. The fourth internal floating piston48has a gas permeable membrane whereby the membrane is attached to the outer side of the fourth internal floating piston48and is permeable to gases but not liquids. The permeability allows the gas but not the oil to pass through the structure thereby the fourth internal floating piston48is able to separate the oil and gas such that the oil is able to occupy the one cell while the gas is able to occupy the second cell. The fourth end cap44acts as a seal such that the oil and gas are confined to the one and second cells; and the confinement allows the oil to have a volume and gas to have both a volume and pressure whereby the gas pressure defines a force.

Referring toFIGS. 52-53, there is shown the four stage air shock whereby each stage is equipped with the internal floating piston, in this case emphasizing the orientation of the four stage air shock:

The four stage air shock is able to be oriented right side up or upside down: referring toFIG. 52, right side up defines the four stage air shock being in a vertical position such that the four stages are arranged in the descending order: first, second, third, and fourth stage whereby the closed end of the working tube32, first dual function shaft33, second dual function shaft34, or third dual function shaft35is at the top of the space within the working tube32, first dual function shaft33, second dual function shaft34, or third dual function35shaft while the first, second, third, or fourth end cap41,42,43or44is at the bottom of the space within the working tube32, first dual function shaft33, second dual function shaft34, or third dual function shaft35whereby the one cell is below the first, second, third, or fourth internal floating piston45,46,47, or48while the second cell is above the first, second, third, or fourth internal floating piston45,46,47, or48, respectively; referring toFIG. 53, upside down is opposite right side up; the opposite defines the four stage air shock being in a vertical position such that the four stages are arranged in the descending order: fourth, third, second, and first stage whereby the closed end of the working tube32, first dual function shaft33, second dual function shaft34, or third dual function shaft35is at the bottom of the space within the working tube32, first dual function shaft33, second dual function shaft34, or third dual function35shaft while the first, second, third, or fourth end cap41,42,43or44is at the top of the space within the working tube32, first dual function shaft33, second dual function shaft34, or third dual function shaft35whereby the one cell is above the first, second, third, or fourth internal floating piston45,46,47, or48while the second cell is below the first, second, third, or fourth internal floating piston45,46,47, or48, respectively.

Referring toFIGS. 54-56, there is shown the four stage air shock whereby each stage is equipped with the internal floating piston, in this case emphasizing the process of charging each stage with oil. Referring toFIG. 54, the four stage air shock is oriented upside down and each stage is fully compressed:

Referring toFIG. 55, the first stage is filled with gas such that the first stage fully extends whereby the filling is performed through the check valve20, the check valve20is attached to the first end cap41. The process of compressing and then filling the first stage is done in order to purge the first stage of moisture. When the first stage fully extends, the first spring49also fully extends whereby the gas, at atmospheric pressure, occupies both the one and second cells of the working tube32. Referring toFIG. 56, the oil charge is added through the check valve20and into the one cell of the working tube32. The fully extended first spring49positions the first internal floating piston45in a manner such that the addition of the oil charge acts to fill up the one cell whereby the gas in the second cell is at atmospheric pressure.

Referring toFIG. 55, the second stage is filled with gas such that the second stage fully extends whereby the filling is performed through the check valve20, the check valve20is attached to the second end cap42. The process of compressing and then filling the second stage is done in order to purge the second stage of moisture. When the second stage fully extends, the second spring50also fully extends whereby the gas, at atmospheric pressure, occupies both the one and second cells of the first dual function shaft33. Referring toFIG. 56, first the oil charge is added through the check valve20and into the one cell of the first dual function shaft33. The fully extended second spring50positions the second internal floating piston46in a manner such that the addition of the oil charge acts to fill up the one cell whereby the gas in the second cell is at atmospheric pressure.

Referring toFIG. 55, the third stage is filled with gas such that the third stage fully extends whereby the filling is performed through the check valve20, the check valve20is attached to the third end cap43. The process of compressing and then filling the third stage is done in order to purge the third stage of moisture. When the third stage fully extends, the third spring51also fully extends whereby the gas, at atmospheric pressure, occupies both the one and second cells of the second dual function shaft34. Referring toFIG. 56, the oil charge is added through the check valve20and into the one cell of the second dual function shaft34. The fully extended third spring51positions the third internal floating piston47in a manner such that the addition of the oil charge acts to fill up the one cell whereby the gas in the second cell is at atmospheric pressure.

Referring toFIG. 55, the fourth stage is filled with gas such that the fourth stage fully extends whereby the filling is performed through the check valve20, the check valve20is attached to the fourth end cap44. The process of compressing and then filling the fourth stage is done in order to purge the fourth stage of moisture. When the fourth stage fully extends, the fourth spring52also fully extends whereby the gas, at atmospheric pressure, occupies both the one and second cells of the third dual function shaft35. Referring toFIG. 56, the oil charge is added through the check valve20and into the one cell of the third dual function shaft35. The fully extended fourth spring52positions the fourth internal floating piston48in a manner such that the addition of the oil charge acts to fill up the one cell whereby the gas in the second cell is at atmospheric pressure.

Referring toFIGS. 57-58, there is shown the four stage air shock whereby each stage is equipped with the internal floating piston and has been charged with oil, in this case emphasizing the process of charging each stage with gas. The four stage air shock is oriented upside down with each stage fully extended:

The first stage is charged with gas by adding the gas charge through the check valve20and into the one cell of the working tube32. Since the oil and gas are immiscible, the oil does not mix with the gas and since the oil and gas occupy the one cell, the oil locates next to the gas such that the surface of the oil contacts that of the gas whereby the contacting surfaces are defined as the interface. The locations of the oil and gas at the interface are defined by density such that the more dense oil will locate below the interface next to the first internal floating piston45while the less dense gas will locate above the interface next to the first end cap41whereby the one cell now contains both the oil and gas charges. The pressure of the gas charge exerts a force on the oil the oil is non-compressible while the first internal floating piston45is impermeable to the oil thereby enabling the oil to transfer the force against the first internal floating piston45. The pressure of the gas charge is greater than atmospheric pressure while the force of the gas pressure is greater than that of the first spring49thereby enabling the force of the gas pressure to cause the first internal floating piston45to slide downward. The downward motion of the first internal floating piston45compresses the first spring49, decreases the volume of the second cell, and increases the pressure of the gas in the second cell; the downward motion continues until the pressure of the gas in the second cell is the same as that of the gas charge. Since the density of the gas is less than that of the oil, the gas in the second cell will exert a force FUPthat acts upward against the first internal floating piston45. Since the first internal floating piston45is permeable to the gas, the upward force FUPdefines an increase in pressure next to the inner side of the first internal floating piston45while there is no change in pressure next to the outer side of the first internal floating piston45. The pressure imbalance defines a pressure differential across the structure of the first internal floating piston45, the pressure differential induces a net flow of gas GFthrough the structure of the first internal floating piston45from the second cell and into the one cell. As soon as the gas from the second cell passes through the first internal floating piston45into the one cell, the gas is able to bubble upward through the oil and accumulate with the gas charge that is next to the first end cap41whereby the gas from the second cell and gas charge are hereafter referred to as the gas. The oil and gas do not mix together such that their surfaces contact one another at the interface whereby the more dense oil is positioned below the interface next to the first internal floating piston45while the less dense gas is positioned above the interface next to the first end cap41. The combination of the flow of the gas GFthrough the structure and the force of the gas pressure being greater than that of the first spring49causes the first internal floating piston45to continue sliding downward until the first internal floating piston45bottoms out against the closed end of the working tube32. The force of the gas pressure serves to hold the first internal floating piston45against the closed end of the working tube32whereby the location of the first internal floating piston45serves to fully compress the first spring49. The space within the working tube32consists of the one cell only.

The second stage is charged with gas by adding the gas charge through the check valve20and into the one cell of the first dual function shaft33. Since the oil and gas are immiscible, the oil does not mix with the gas and since the oil and gas occupy the one cell, the oil locates next to the gas such that the surface of the oil contacts that of the gas whereby the contacting surfaces are defined as the interface. The locations of the oil and gas at the interface are defined by density such that the more dense oil will locate below the interface next to the second internal floating piston46while the less dense gas will locate above the interface next to the second end cap42whereby the one cell now contains both the oil and gas charges. The pressure of the gas charge exerts a force on the oil the oil is non-compressible while the second internal floating piston46is impermeable to the oil thereby enabling the oil to transfer the force against the second internal floating piston46. The pressure of the gas charge is greater than atmospheric pressure while the force of the gas pressure is greater than that of the second spring50thereby enabling the force of the gas pressure to cause the second internal floating piston46to slide downward whereby the downward motion of the second internal floating piston46compresses the second spring50, decreases the volume of the second cell, and increases the pressure of the gas in the second cell; the downward motion continues until the pressure of the gas in the second cell is the same as that of the gas charge. Since the density of the gas is less than that of the oil, the gas in the second cell will exert a force FUPthat acts upward against the second internal floating piston46. Since the second internal floating piston46is permeable to the gas, the upward force FUPdefines an increase in pressure next to the inner side of the second internal floating piston46while there is no change in pressure next to the outer side of the second internal floating piston46. The pressure imbalance defines a pressure differential across the structure of the second internal floating piston46whereby the pressure differential induces a net flow of gas GFthrough the structure of the second internal floating piston46from the second cell and into the one cell. As soon as the gas from the second cell passes through the second internal floating piston46into the one cell, the gas is able to bubble upward through the oil and accumulate with the gas charge that is next to the second end cap42whereby the gas from the second cell and gas charge are hereafter referred to as the gas. The oil and gas do not mix together such that their surfaces contact one another at the interface whereby the more dense oil is positioned below the interface next to the second internal floating piston46while the less dense gas is positioned above the interface next to the second end cap42. The combination of the flow of the gas GFthrough the structure and the force of the gas pressure being greater than that of the second spring50causes the second internal floating piston46to continue sliding downward until the second internal floating piston46bottoms out against the closed end of the first dual function shaft33. The force of the gas pressure serves to hold the second internal floating piston46against the closed end of the first dual function shaft33whereby the location of the second internal floating piston46serves to fully compress the second spring50. The space within the first dual function shaft33consists of the one cell only.

The third stage is charged with gas by adding the gas charge through the check valve20and into the one cell of the second dual function shaft34. Since the oil and gas are immiscible, the oil does not mix with the gas and since the oil and gas occupy the one cell, the oil locates next to the gas such that the surface of the oil contacts that of the gas whereby the contacting surfaces are defined as the interface. The locations of the oil and gas at the interface are defined by density such that the more dense oil will locate below the interface next to the third internal floating piston47while the less dense gas will locate above the interface next to the third end cap43whereby the one cell now contains both the oil and gas charges. The pressure of the gas charge exerts a force on the oil the oil is non-compressible while the third internal floating piston47is impermeable to the oil thereby enabling the oil to transfer the force against the third internal floating piston47. The pressure of the gas charge is greater than atmospheric pressure while the force of the gas pressure is greater than that of the third spring51thereby enabling the force of the gas pressure to cause the third internal floating piston47to slide downward whereby the downward motion of the third internal floating piston47compresses the third spring51, decreases the volume of the second cell, and increases the pressure of the gas in the second cell; the downward motion continues until the pressure of the gas in the second cell is the same as that of the gas charge. Since the density of the gas is less than that of the oil, the gas in the second cell will exert a force FUPthat acts upward against the third internal floating piston47. Since the third internal floating piston47is permeable to the gas, the upward force FUPdefines an increase in pressure next to the inner side of the third internal floating piston47while there is no change in pressure next to the outer side of the third internal floating piston47. The pressure imbalance defines a pressure differential across the structure of the third internal floating piston47whereby the pressure differential induces a net flow of gas GFthrough the structure of the third internal floating piston47from the second cell and into the one cell. As soon as the gas from the second cell passes through the third internal floating piston47into the one cell, the gas is able to bubble upward through the oil and accumulate with the gas charge that is next to the third end cap43whereby the gas from the second cell and gas charge are hereafter referred to as the gas. The oil and gas do not mix together such that their surfaces contact one another at the interface whereby the more dense oil is positioned below the interface next to the third internal floating piston47while the less dense gas is positioned above the interface next to the third end cap43. The combination of the flow of the gas GFthrough the structure and the force of the gas pressure being greater than that of the third spring51causes the third internal floating piston47to continue sliding downward until the third internal floating piston47bottoms out against the closed end of the second dual function shaft34. The force of the gas pressure serves to hold the third internal floating piston47against the closed end of the second dual function shaft34whereby the location of the third internal floating piston47serves to fully compress the third spring51. The space within the second dual function shaft34consists of the one cell only.

The fourth stage is charged with gas by adding the gas charge through the check valve20and into the one cell of the third dual function shaft35. Since the oil and gas are immiscible, the oil does not mix with the gas and since the oil and gas occupy the one cell, the oil locates next to the gas such that the surface of the oil contacts that of the gas whereby the contacting surfaces are defined as the interface. The locations of the oil and gas at the interface are defined by density such that the more dense oil will locate below the interface next to the fourth internal floating piston48while the less dense gas will locate above the interface next to the fourth end cap44whereby the one cell now contains both the oil and gas charges. The pressure of the gas charge exerts a force on the oil the oil is non-compressible while the fourth internal floating piston48is impermeable to the oil thereby enabling the oil to transfer the force against the fourth internal floating piston48. The pressure of the gas charge is greater than atmospheric pressure while the force of the gas pressure is greater than that of the fourth spring52thereby enabling the force of the gas pressure to cause the fourth internal floating piston48to slide downward whereby the downward motion of the fourth internal floating piston48compresses the fourth spring52, decreases the volume of the second cell, and increases the pressure of the gas in the second cell; the downward motion continues until the pressure of the gas in the second cell is the same as that of the gas charge. Since the density of the gas is less than that of the oil, the gas in the second cell will exert a force FUPthat acts upward against the fourth internal floating piston48. Since the fourth internal floating piston48is permeable to the gas, the upward force FUPdefines an increase in pressure next to the inner side of the fourth internal floating piston48while there is no change in pressure next to the outer side of the fourth internal floating piston48. The pressure imbalance defines a pressure differential across the structure of the fourth internal floating piston48whereby the pressure differential induces a net flow of gas GFthrough the structure of the fourth internal floating piston48from the second cell and into the one cell. As soon as the gas from the second cell passes through the fourth internal floating piston48into the one cell, the gas is able to bubble upward through the oil and accumulate with the gas charge that is next to the fourth end cap44whereby the gas from the second cell and gas charge are hereafter referred to as the gas. The oil and gas do not mix together such that their surfaces contact one another at the interface whereby the more dense oil is positioned below the interface next to the fourth internal floating piston48while the less dense gas is positioned above the interface next to the fourth end cap44. The combination of the flow of the gas GFthrough the structure and the force of the gas pressure being greater than that of the fourth spring52causes the fourth internal floating piston48to continue sliding downward until the fourth internal floating piston48bottoms out against the closed end of the third dual function shaft35. The force of the gas pressure serves to hold the fourth internal floating piston48against the closed end of the third dual function shaft35whereby the location of the fourth internal floating piston48serves to fully compress the fourth spring52. The space within the third dual function shaft35consists of the one cell only.

Referring toFIGS. 59-61, there is shown the four stage air shock whereby each stage is equipped with the internal floating piston and has been charged with oil and gas, in this case emphasizing the process of the internal floating piston separating the oil and gas into one and the other cells, respectively. The four stage air shock is rotated 180 degrees from being upside down to right side up:

For the first stage, the rotation causes the oil and gas to reverse positions in the one cell of the working tube32such that the oil is positioned below the interface next to the first end cap41while the gas is positioned above the interface next to the first internal floating piston45. Since the first internal floating piston45is permeable to the gas, the gas is able to flow through the first internal floating piston45. The ability to flow indicates that the force of the gas pressure is able to have no effect on the first internal floating piston45, and instead acts against the closed end of the working tube32. The absence of the effect cancels the force of the gas pressure that holds the first internal floating piston45against the closed end of the working tube32. The lack of the first internal floating piston45being held against the closed end of the working tube32allows the first spring49to extend. The extension of the first spring49exerts the force FSPagainst the first internal floating piston45thereby causing the first internal floating piston45to slide downward MDagainst the gas whereby the downward motion MDcreates a greater pressure zone next to the outer side of the first internal floating piston45while an equivalent lower pressure zone is created next to the inner side of the first internal floating piston45. The pressure imbalance defines the pressure differential across the structure of the first internal floating piston45. The pressure differential induces the net flow of gas GFthrough the structure of the first internal floating piston45from the one cell and into the second cell such that the oil occupies the one cell and the gas occupies the second cell.

For the second stage, the rotation causes the oil and gas to reverse positions in the one cell of the first dual function shaft33such that the oil is positioned below the interface next to the second end cap42while the gas is positioned above the interface next to the second internal floating piston46. Since the second internal floating piston46is permeable to the gas, the gas is able to flow through the second internal floating piston46. The ability to flow indicates that the force of the gas pressure is able to have no effect on the second internal floating piston46, and instead acts against the closed end of the first dual function shaft33. The absence of the effect cancels the force of the gas pressure that holds the second internal floating piston46against the closed end of the first dual function shaft33. The lack of the second internal floating piston46being held against the closed end of the first dual function shaft33allows the second spring50to extend. The extension of the second spring50exerts the force FSPagainst the second internal floating piston46thereby causing the second internal floating piston46to slide downward MDagainst the gas whereby the downward motion MDcreates a greater pressure zone next to the outer side of the second internal floating piston46while an equivalent lower pressure zone is created next to the inner side of the second internal floating piston46. The pressure imbalance defines the pressure differential across the structure of the second internal floating piston46. The pressure differential induces the net flow of gas GFthrough the structure of the second internal floating piston46from the one cell and into the second cell such that the oil occupies the one cell and the gas occupies the second cell.

For the third stage, the rotation causes the oil and gas to reverse positions in the one cell of the second dual function34shaft such that the oil is positioned below the interface next to the third end cap43while the gas is positioned above the interface next to the third internal floating piston47. Since the third internal floating piston47is permeable to the gas, the gas is able to flow through the third internal floating piston47. The ability to flow indicates that the force of the gas pressure is able to have no effect on the third internal floating piston47, and instead acts against the closed end of the second dual function34. The absence of the effect cancels the force of the gas pressure that holds the third internal floating piston47against the closed end of the second dual function shaft34. The lack of the third internal floating piston47being held against the closed end of the second dual function shaft34allows the third spring51to extend. The extension of the third spring51exerts the force FSPagainst the third internal floating piston47thereby causing the third internal floating piston47to slide downward MDagainst the gas whereby the downward motion MDcreates a greater pressure zone next to the outer side of the third internal floating piston47while an equivalent lower pressure zone is created next to the inner side of the third internal floating piston47. The pressure imbalance defines the pressure differential across the structure of the third internal floating piston47. The pressure differential induces the net flow of gas GFthrough the structure of the third internal floating piston47from the one cell and into the second cell such that the oil occupies the one cell and the gas occupies the second cell.

For the fourth stage, the rotation causes the oil and gas to reverse positions in the one cell of the third dual function shaft35such that the oil is positioned below the interface next to the fourth end cap44while the gas is positioned above the interface next to the fourth internal floating piston48. Since the fourth internal floating piston48is permeable to the gas, the gas is able to flow through the fourth internal floating piston48. The ability to flow indicates that the force of the gas pressure is able to have no effect on the fourth internal floating piston48, and instead acts against the closed end of the third dual function shaft35. The absence of the effect cancels the force of the gas pressure that holds the fourth internal floating piston48against the closed end of the third dual function shaft35. The lack of the fourth internal floating piston48being held against the closed end of the third dual function shaft35allows the fourth spring52to extend. The extension of the fourth spring52exerts the force FSPagainst the fourth internal floating piston48thereby causing the fourth internal floating piston48to slide downward MDagainst the gas whereby the downward motion MDcreates a greater pressure zone next to the outer side of the fourth internal floating piston48while an equivalent lower pressure zone is created next to the inner side of the fourth internal floating piston48. The pressure imbalance defines the pressure differential across the structure of the fourth internal floating piston48. The pressure differential induces the net flow of gas GFthrough the structure of the fourth internal floating piston48from the one cell and into the second cell such that the oil occupies the one cell and the gas occupies the second cell.

Referring toFIGS. 62-64, there is shown the four stage air shock whereby each stage is equipped with the internal floating piston and charged with oil and gas. The oil and gas occupy the one and second cells, respectively, and each internal floating piston utilizes a membrane that possesses a slow permeation rate. In this case emphasis is placed on the motion of each internal floating piston during the operation of each stage, the operation of each stage being caused by suspension forces acting on each stage: referring to:FIG. 62, the first, second, third, and fourth stages are all fully extended;FIG. 63, the first, second, third, and fourth stages are all fully compressed; andFIG. 64, the first and second stages are fully extended while the third stage is compressed to 70% of shaft stroke and fourth stage is compressed to 40% of shaft stroke:

Regarding operation of the first stage: (a) during compression the suspension forces are exerted on the first dual function shaft33thereby causing the first dual function shaft33to slide into the working tube32whereby the sliding motion of the first dual function shaft33pushes the first working piston37through the oil. The suspension forces that are exerted on the first dual function shaft33are transferred to the oil, in turn, the suspension forces that are exerted on the oil are transferred to the first internal floating piston45, in turn, the suspension forces that are exerted on the first internal floating piston45cause the first internal floating piston45to slide towards the closed end of the working tube32. The motion of the first internal floating piston45decreases the volume of the second cell whereby the decrease in the volume of the second cell refers to a decrease in the volume of the first stage and causes an increase in the gas pressure; (b) during extension the force of the gas pressure is transferred to the first internal floating piston45, in turn, the force of the gas pressure that is exerted on the first internal floating piston45is transferred to the oil, in turn, the force of the gas pressure that is exerted on the oil is transferred to the first dual function shaft33thereby causing the first dual function shaft33to slide out of the working tube32whereby the sliding motion of the first dual function shaft33pulls the first working piston37through the oil. The slow permeation rate of the membrane ensures that the oil and gas remain separated and occupy the one and second cells, respectively, thereby ensuring that the force of the gas pressure is exerted on the first internal floating piston45and then transferred from the first internal floating piston45to the oil such that the first internal floating piston45is able to slide away from the closed end of the working tube32and move in conjunction with the first dual function shaft33. The motion of the first internal floating piston45increases the volume of the second cell whereby the increase in the volume refers to an increase in the volume of the first stage and causes a decrease in the pressure of the gas. The change in pressure of the gas in the first stage causes the suspension spring movement of the first stage whereby the suspension spring movement of the first stage is dampened by the movement of the first working piston37through the oil. The length of the first dual function shaft33from full extension to full compression or vice versa refers to the first dual function shaft stroke LD1or shaft stroke of the first stage LD1.

Regarding operation of the second stage: (a) during compression the suspension forces are exerted on the second dual function shaft34thereby causing the second dual function shaft34to slide into the first dual function shaft33whereby the sliding motion of the second dual function shaft34pushes the second working piston38through the oil. The suspension forces that are exerted on the second dual function shaft34are transferred to the oil, in turn, the suspension forces that are exerted on the oil are transferred to the second internal floating piston46, in turn, the suspension forces that are exerted on the second internal floating piston46cause the second internal floating piston46to slide towards the closed end of the first dual function shaft33. The motion of the second internal floating piston46decreases the volume of the second cell whereby the decrease in the volume of the second cell refers to a decrease in the volume of the second stage and causes an increase in the gas pressure; (b) during extension the force of the gas pressure is transferred to the second internal floating piston46, in turn, the force of the gas pressure that is exerted on the second internal floating piston46is transferred to the oil, in turn, the force of the gas pressure that is exerted on the oil is transferred to the second dual function shaft34thereby causing the second dual function shaft34to slide out of the first dual function shaft33whereby the sliding motion of the second dual function shaft34pulls the second working piston38through the oil. The slow permeation rate of the membrane ensures that the oil and gas remain separated and occupy the one and second cells, respectively, thereby ensuring that the force of the gas pressure is exerted on the second internal floating piston46and then transferred from the second internal floating piston46to the oil such that the second internal floating piston46is able to slide away from the closed end of the first dual function shaft33and move in conjunction with the second dual function shaft34. The motion of the second internal floating piston46increases the volume of the second cell whereby the increase in the volume refers to an increase in the volume of the second stage and causes a decrease in the pressure of the gas. The change in pressure of the gas in the second stage causes the suspension spring movement of the second stage whereby the suspension spring movement of the second stage is dampened by the movement of the second working piston38through the oil. The length of the second dual function shaft34from full extension to full compression or vice versa refers to the second dual function shaft stroke LD2or shaft stroke of the second stage LD2.

Regarding operation of the third stage: (a) during compression the suspension forces are exerted on the third dual function shaft35thereby causing the third dual function shaft35to slide into the second dual function shaft34whereby the sliding motion of the third dual function shaft35pushes the third working piston39through the oil. The suspension forces that are exerted on the third dual function shaft35are transferred to the oil, in turn, the suspension forces that are exerted on the oil are transferred to the third internal floating piston47, in turn, the suspension forces that are exerted on the third internal floating piston47cause the third internal floating piston47to slide towards the closed end of the second dual function shaft34. The motion of the third internal floating piston47decreases the volume of the second cell whereby the decrease in the volume of the second cell refers to a decrease in the volume of the third stage and causes an increase in the gas pressure; (b) during extension the force of the gas pressure is transferred to the third internal floating piston47, in turn, the force of the gas pressure that is exerted on the third internal floating piston47is transferred to the oil, in turn, the force of the gas pressure that is exerted on the oil is transferred to the third dual function shaft35thereby causing the third dual function shaft35to slide out of the second dual function shaft34whereby the sliding motion of the third dual function shaft35pulls the third working piston39through the oil. The slow permeation rate of the membrane ensures that that oil and gas remain separated and occupy the one and second cells, respectively, thereby ensuring that the force of the gas pressure is exerted on the third internal floating piston47and then transferred from the third internal floating piston47to the oil such that the third internal floating piston47is able to slide away from the closed end of the second dual function shaft34and move in conjunction with the third dual function shaft35. The motion of the third internal floating piston47increases the volume of the second cell whereby the increase in the volume refers to an increase in the volume of the third stage and causes a decrease in the pressure of the gas. The change in pressure of the gas in the third stage causes the suspension spring movement of the third stage whereby the suspension spring movement of the third stage is dampened by the movement of the third working piston39through the oil. The length of the third dual function shaft35from full extension to full compression or vice versa refers to the third dual function shaft stroke LD3or shaft stroke of the third stage LD3.

Regarding operation of the fourth stage: (a) during compression the suspension forces are exerted on the single function shaft36thereby causing the single function shaft36to slide into the third dual function shaft35whereby the sliding motion of the single function shaft36pushes the fourth working piston40through the oil. The suspension forces that are exerted on the single function shaft36are transferred to the oil, in turn, the suspension forces that are exerted on the oil are transferred to the fourth internal floating piston48, in turn, the suspension forces that are exerted on the fourth internal floating piston48cause the fourth internal floating piston48to slide towards the closed end of the third dual function shaft35. The motion of the fourth internal floating piston48decreases the volume of the second cell whereby the decrease in the volume of the second cell refers to a decrease in the volume of the fourth stage and causes an increase in the gas pressure; (b) during extension the force of the gas pressure is transferred to the fourth internal floating piston48, in turn, the force of the gas pressure that is exerted on the fourth internal floating piston48is transferred to the oil, in turn, the force of the gas pressure that is exerted on the oil is transferred to the single function shaft36thereby causing the single function shaft36to slide out of the third dual function shaft35whereby the sliding motion of the single function shaft36pulls the fourth working piston40through the oil. The slow permeation rate of the membrane ensures that that oil and gas remain separated and occupy the one and second cells, respectively, thereby ensuring that the force of the gas pressure is exerted on the fourth internal floating piston48and then transferred from the fourth internal floating piston48to the oil such that the fourth internal floating piston48is able to slide away from the closed end of the third dual function shaft35and move in conjunction with the single function shaft36. The motion of the fourth internal floating piston48increases the volume of the second cell whereby the increase in the volume refers to an increase in the volume of the fourth stage and causes a decrease in the pressure of the gas. The change in pressure of the gas in the fourth stage causes the suspension spring movement of the fourth stage whereby the suspension spring movement of the fourth stage is dampened by the movement of the fourth working piston40through the oil. The length of the single function shaft36from full extension to full compression or vice versa refers to the single function shaft stroke LD4or shaft stroke of the fourth stage LD4.

Referring toFIGS. 65-83, there is shown the effect of the internal floating piston on the compressed and extended lengths of the four stage air shock whereby each stage is equipped with the internal floating piston. For purposes of discussion, (1) the shaft refers to the first, second, or third dual function shaft or single function shaft while the component refers to the working tube or first, second, or third dual function shaft, (2) the four stage air shock that has an internal floating piston in each stage is referred to as the internal floating piston equipped four stage air shock:

The compressed and extended lengths are determined using a modified form of the one methodology that was disclosed in patent application Ser. No. 14/935,423. Referring toFIGS. 65and66, the modification refers to the incorporation of the thickness ipnof the internal floating piston into the set of equations used in the computations where n=1-8. Referring toFIGS. 67-72, there are shown the set of equations that are used to compute the compressed and extended lengths of the internal floating piston equipped four stage air shock. The following dimensions are used in the equations: extended length, ELX, compressed length, CLX, length of the working tube, LX, length of the nth dual or single function shaft, LWn, shaft stroke of the nth stage, LSn, thickness of the nth working piston, wpn, shaft shoulder, ssn, end cap, ecn, or internal floating piston, ipn, and thickness of the mounting eyelet, me where X or n=1-8. Values are selected for the length of the working tube, L1, thicknesses of the nth working piston, wpn, shaft shoulder, ssn, end cap, ecn, and internal floating piston, ipn, and thickness of the mounting eyelet, me. Referring toFIG. 83, there is shown the selected value for the length of the working tube, L1; referring toFIGS. 75-82, there are shown the selected values for the thicknesses of the nth working piston wpn, shaft shoulder ssn, and end cap ecn; referring toFIG. 73, there is shown the selected value for the mounting eyelet, me; and referring toFIG. 74, there is shown the relationship between the thickness of the nth internal floating piston, ipn, and that of the nth working piston, wpn.

Since the internal floating piston is inserted into the space within the component and since the working piston and shaft shoulder are also in the space within the component whereby the shaft is shorter than the component in order to account for the thicknesses of the working piston and shaft shoulder such that the shaft is able to slide fully into the component, then the thickness of the internal floating piston must also be accounted for when determining the length of the shaft; in particular, the shaft must be shorter than the component in order to account for the thicknesses of the working piston, shaft shoulder and internal floating piston such that the shaft is able to slide fully into the component. Specifically, the length of the shaft is the sum of the length of the component less the thicknesses of the working piston, shaft shoulder, and internal floating piston plus the end cap; while, the shaft stroke of each stage is the sum of the length of each component less the thicknesses of each working piston, shaft shoulder, and internal floating piston. This way, the thickness of the internal floating piston serves to decrease the length of the shaft or shaft stroke of each stage.

Since the extended length is computed as the sum of the compressed length plus the shaft stroke of each stage and since the thickness of the internal floating piston serves to decrease the shaft stroke of each stage, then the extended length of the internal floating piston equipped four stage air shock is less than that of the four stage air shock. Referring toFIG. 83, there is shown the data table with values for the compressed and extended lengths of the internal floating piston equipped four stage air shock: for example given a compressed length of 13.50 inches and that other dimensions have the same values for both the internal floating piston equipped four stage air shock and four stage air shock, then the extended length for the internal floating piston equipped four stage air shock is 30.50 inches while that for the four stage air shock is 38.00 inches.

This analysis emphasizes that the incorporation of the internal floating piston into each stage leads to a decrease in the extended length of the multiple stage air shock. Even though the selected values for the thicknesses of each working piston, shaft shoulder, end cap, and mounting eyelet are the same, the shaft stroke of each stage must be shortened in order to account for the thickness of each internal floating piston. Since the extended length of the multiple stage air shock is directly related to the shaft stroke of each stage, then the extended length is decreased for each internal floating piston that is incorporated into each stage of the multiple stage air shock.

Note: referring toFIGS. 73-82and L1inFIG. 83, the dimensions and values listed therein are selected for purposes of discussion only and are not meant to imply proper values for any stage in the multiple stage air shock.

Referring toFIGS. 84-104, there is shown the effect of the internal floating piston on the spring rate for the four stage air shock whereby each stage is equipped with the internal floating piston. For purposes of discussion, (1) the shaft refers to the first, second, or third dual function shaft or single function shaft while the component refers to the working tube or first, second, or third dual function shaft, (2) the four stage air shock that has an internal floating piston in each stage is referred to as the internal floating piston equipped four stage air shock, and (3) in principle, the force of the spring serves to push the shaft out of the component and indirectly increase the force of the gas pressure. However, this spring force is ignored regarding spring rates because the spring is designed to create a pressure differential across the structure of the internal floating piston and is not nearly strong enough to serve as a suspension spring:

The spring rate is estimated using the same second methodology that was used for the four stage air shock disclosed in patent application Ser. No. 14/935,423; however, the selected data for the shaft strokes for each stage in the internal floating piston equipped four stage air shock are different than those selected for each stage in the four stage air shock. Referring toFIGS. 84 and 85, the difference refers to the internal floating piston being inserted into the space within the component. When compared to the shaft stroke for each stage in the four stage air shock, the shaft stroke for each stage in the internal floating piston equipped four stage air shock must be shortened in order to account for the thickness of the internal floating piston. Since the shaft stroke directly relates to the volume of the shaft stroke or volume of the gas, then when compared to the volume of the shaft stroke for each stage in the four stage air shock the volume of the shaft stroke for each stage in the internal floating piston equipped four stage air shock is decreased in proportion to the decrease in shaft stroke for each stage, and in turn, the volume of the gas is decreased in proportion to the decrease in shaft stroke for each stage.

Referring toFIGS. 86-97, there is shown a set of equations used to compute various dimensions of the internal floating piston equipped four stage air shock The set of equations are excerpted from patent application Ser. No. 14/935,423 thereby representing part of the same equations defined in the second methodology while the dimensions and the symbols depicting the dimensions are the same as those defined in the second methodology.

Referring toFIG. 98, there are shown the selected values for the diameter of each stage, DD1, DD2, DD3, DS1, shaft stroke of each stage, LD1, LD2, LD3, LS1, suspension force exerted on each stage at ride height, F1-4, and percent of the shaft stroke not compressed at ride height for each stage, % L1-4The values selected for DD1, DD2, DD3, DS1, F1-4and % L1-4are the same as those selected for the four stage air shock disclosed in patent application Ser. No. 14/935,423; whereas the values selected for LD1, LD2, LD3, LS1are different from those selected for the four stage air shock disclosed in patent application Ser. No. 14/935,423, the values being the same as those for LS1-4that are computed with the modified form of the one methodology described above, respectively.

Referring toFIGS. 99-104, there are shown data tables and graphs. InFIGS. 99-102, the data tables comprise the following dimensions for each stage in the internal floating piston equipped four stage air shock: the selected incremental shaft stroke, LZ, percent change in incremental shaft stroke, %ΔLZ, suspension force, FZ, change in incremental shaft stroke, ΔLZ, and spring rate, SRZwhere ZΞ1e, 2f, 3g, and 4h for the first, second, third, and fourth stage, respectively. InFIGS. 103 and 104, the graphs show the estimate of the spring rate for the internal floating piston equipped four stage air shock whereby the values for the suspension force FZand change in incremental shaft stroke ΔLZare used to derive the graphs. In particular, the values for FZfor the internal floating piston equipped four stage air shock are the same or nearly the same as those for the four stage air shock while the values for ΔLZfor the internal floating piston equipped four stage air shock are different from those for the four stage air shock, the difference being due to the difference in the shaft stroke Ln.

The shortened shaft stroke Lnin the internal floating piston equipped four stage air shock produces a change in incremental shaft stroke ΔLZthat is less than that for the four stage air shock. For example referring toFIGS. 99-102, the change in incremental shaft strokes ΔLZfor the first, second, third, and fourth stages in the internal floating piston equipped four stage air shock are 0.63, 0.48, 0.35, and 0.25 while those for the first, second, third, and fourth stages in the four stage air shock are 0.71, 0.63, 0.58, and 0.53, respectively. Referring toFIGS. 103 and 104, there are shown the curved lines53,54,55, and56for the first, second, third, and fourth stages in the internal floating piston equipped four stage air shock plotted on graphs whereby the curved lines and graphs are derived with the second methodology. Since the change in incremental shaft stroke ΔLZis used to determine the spacing between adjacent data points that are plotted for each curved line, then the spacing between adjacent data points that are plotted for each curved line for the internal floating piston equipped four stage air shock are less than those for the four stage air shock. In principle this decreased spacing results in a gradually sloping curved line part for each stage in the internal floating piston equipped four stage air shock being slightly steeper than that for the four stage air shock. Yet, a comparison of the dotted line trace57for the internal floating piston equipped four stage air with that for the four stage air shock reveals that the slope of the dotted line trace57for the internal floating piston equipped four stage air looks the same as that for the four stage air shock. More importantly, the dotted line trace57for the internal floating piston equipped four stage air is relatively straight thereby suggesting that the spring rate for the internal floating piston equipped four stage air shock is relatively linear. Indeed, the shape of the dotted line trace57for the internal floating piston equipped four stage air shock looks virtually the same as for the four stage air shock.

This analysis emphasizes that given similar selected values for the dimensions of each stage in the multiple stage air shock, then the estimate of the spring rate for the internal floating piston equipped four stage air shock is virtually the same as that for the four stage air shock. Since the selected values for the dimensions of each stage in the internal floating piston equipped four stage air shock are the same as that for the four stage air shock, except for shaft stroke, then the estimate is not affected by changes in the selected values of the shaft stroke. The estimate is not affected by changes in the selected values of the shaft stroke because the estimate is based on the computed values of the suspension force, FZ, and the computed values of FZare not affected by changes in the selected values of the shaft strokes. The computed values of FZare not affected by changes in the selected values of the shaft strokes because the changes in the selected values of the shaft strokes cause a proportional decrease in other dimensions, or the shaft strokes are factored or canceled out in the computations of other dimensions.

Note: referring toFIGS. 98-102, the properties and values listed therein are selected for purposes of discussion only and are not meant to imply proper values for any stage in a multiple stage air shock.

While the invention has been illustrated and described as a device that separates the oil from the gas in a shock absorbing and spring product, it is not intended to be limited to the details shown, since it will be understood that various omissions, modifications, substitutions and changes in the forms and details of the device illustrated and in its operation can be made by those skilled in the art without departing in any way from the scope and spirit of the present invention.