Active air spring

Abstract

An active air spring regulates and controls compression and rebound travel, speed, and shock position by modulating internal pressures in an air bag and/or air cylinder in real time by varying the internal volume of discrete air reservoirs in fluid connection with one another as controlled by valves, venting, and self-pressurization.

Claims

1. An active air spring for use on vehicles, comprising: an air bag spring which includes a compressible air bag having an upper end and a lower end, said upper end sealingly connected to a first mount; an air cylinder having an upper end and a lower end and defining an interior gas volume, said air cylinder having a pressure side gas port and a vacuum side gas port and having a second mount disposed on said lower end; a fitting sealingly coupling said air bag to said air cylinder and having a gas control port in fluid communication with said interior gas volume of said air bag; a piston having a piston rod connected at one end to said first mount, slidingly passing through said fitting, and coupled at a second end to a piston head slidingly disposed in said air cylinder, said piston head having an upper side defining a negative pressure side of said air cylinder and a lower side defining a positive pressure side of said air cylinder; a fluid line connecting said pressure side gas port, said vacuum side gas port, and said gas control port; and an adjustable control valve disposed on said fluid line that may be set to be selectively or automatically responsive to shock conditions to regulate gas flow from said positive pressure side of said air cylinder interior gas volume to said negative pressure side of said air cylinder; wherein said air bag spring modulates internal air cylinder pressures by changing the relative pressures of said positive pressure side and said negative pressure side through said fluid line and said adjustable control valve to control compression and rebound travel and speed and shock position.

2. The active air spring of claim 1, wherein said air spring is both a spring and a damper and switches functions according to impact conditions.

3. The active air spring of claim 1, wherein a vacuum on said negative pressure side of said air chamber is employed to lock said piston in position and to be released spontaneously to respond to an impact.

4. The active air spring of claim 1, wherein when said compressible air bag is compressed, a vacuum or negative pressure forms on said negative pressure side of said piston head and a positive pressure forms on said positive pressure side.

5. The active air spring of claim 4, wherein when said control valve is in a closed position, said piston is locked in an extended position.

6. The active air spring of claim 5, wherein said control valve may be selectively opened in varying degrees to control shock movement by placing said gas control port, said pressure side gas port, and said vacuum side gas port into varying degrees of fluid communication with one another and with ambient air.

7. The active air spring of claim 6, wherein said control valve controls pressures and vacuums to adjust shock velocity and position.

Description

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

(1) FIG. 1 is a schematic side view in elevation showing the inventive air spring installed on the front shocks of a bicycle;

(2) FIG. 2 is a highly schematic cross-sectional side view in elevation of an embodiment of the active air spring of the invention;

(3) FIG. 3 is an upper perspective view of another embodiment having an air pump installed alongside the air cylinder and air bag to move in direct relation to spring movements and thus “read” spring speed and movement;

(4) FIG. 4 is a highly schematic cross-sectional side view in elevation of an alternative embodiment.

DESCRIPTION OF THE INVENTION

(5) Referring to FIGS. 1 through 4, wherein like reference numerals refer to like components in the various views, there is illustrated therein a new and improved air spring for a shock absorber system for vehicles, generally denominated 10 herein. FIG. 1 shows the invention 10 installed on a typical mountain bike B, a vehicle selected for illustrative purposes but not defining or limiting the potential fields of use. Here it is seen that the air spring may be mounted on the steering tube ST or fork crown FC at the upper end of the stanchions S, and the fork arch (or brace) FA ad the upper end of the lowers L of a mountain bike.

(6) In an embodiment 10, as shown in FIG. 2, the air shock of the present invention includes a gas (air) cylinder 12, a piston 14, and a compressible air bag 16 stacked in either orientation (air bag above air cylinder or the reverse) to create a unified shock absorber 10. The air bag is sealingly coupled at its lower end 18 to the air cylinder with a fitting 20, which allows passage of the reciprocating piston rod 22 and includes a gas control port 24 in fluid communication with the interior gas volume 26 of the air bag.

(7) A first mount (eyelet) 28 sealingly couples to the upper end of the air bag and to the upper end 30 of the piston rod 22, and a second mount (eyelet) 32 is integral with or affixed to the end 34 of the bottom side 36 of air cylinder 12. The upper mount attaches to a vehicle frame while the lower mount attaches to moving wheel structure, in a manner well known in the art.

(8) Air cylinder 12 includes a pressure side control port 38 and a vacuum side control port 40 in fluid communication with one another and with the air bag gas control port 24 through a fluid line 42 with a control valve 44 that may be manually set and/or automatically responsive to shock conditions to regulate flow from the positive pressure side 46 of the air cylinder interior volume to the negative pressure (vacuum) side 48 of the air cylinder, which correspond, respectively, to the upper and lower sides of the piston head 50.

(9) When the shock is compressed, a vacuum or negative pressure forms on the vacuum side 48 of piston head 50, while a positive pressure forms on the positive pressure side 46. If desired, control valve 44 may be set to remain closed and the piston thus remains locked in the expanded position. Otherwise, control valve 44 can be opened or set to open in varying degrees to control shock movement by placing the control ports 24, 38, 40 into varying degrees of fluid communication with one another and with ambient air. Control valve 44 can spontaneously control pressures and vacuums and in turn shock velocity and position. Not shown are intake and exhaust valves in air cylinder 12 which may be installed to enable it to act as an air pump with shock movement, as desired. Also, as will be appreciated, piston head 50 includes packing and rings to slidingly seal the head within and against the interior side of air cylinder 12 so as to prevent air bleeding past piston head 50 when in operation. The structures required to accomplish such a seal are well known and in no need of detailed description here.

(10) FIG. 3 shows an alternative embodiment of the inventive air spring, which include all of the elements of FIG. 2 in primary shock assembly 72 (thus promoting and importing those elements herein), as well as a supplementary air pump 74 in fluid communication with the air cylinder 76. Air cylinder and air bag porting and coupling are the same as recited with respect to FIG. 2. Here, however, an air pump is provided to be responsive to shock movements. The assembly is installed, for instance, on the fork arch FA and steering tube ST or fork crown FC of a mountain bike. The air pump include a reciprocating piston 78 having a piston rod 80 with an eyelet 82 secured with a bolt 84 coaxially disposed through eyelet 82 and lower mount 84 of the primary shock assembly 72. A movement sensor 86 detects movements of piston 80 within the air pump and 74 and opens or closes the control valve (not shown in this view) for the primary shock assembly 72. Further, the air pump is in fluid communication with the positive pressure side 88 of the air cylinder 76 through a gas line 90, the gas movement controlled by a two way valve 92. In compression, the control valve is closed and air spring piston movement is fully enabled. The movement sensor may open the control valve in proportion to impact forces, thereby equalizing piston pressure. The movement sensor also detects rebound and actuates the air spring control valve to open and equalize pressure in the air spring cylinder, thereby enabling the air spring bag to rebound a predetermined percentage of spring power.

(11) Referring next to FIG. 4, in another embodiment 100 the inventive air spring is formed in a conventional fashion for incorporation in a telescoping fork of the kind shown in FIG. 2. This embodiment includes a cylinder 102, a piston head 104 and a connecting rod 106. The connecting rod and cylinder are connected between the stanchions and the lowers of a telescoping fork to act as a spring. In this configuration the piston has a negative pressure (vacuum) side 108, and a positive pressure side 110. Air lines 112 connect the vacuum side and positive pressure side through variable vacuum reservoir valve 114, and 116, to their respective corresponding reservoirs, variable vacuum reservoir 118, and pressure reservoir 120, preferably mounted on the crown of the telescoping forks.

(12) When the telescoping fork is weighted and compressed, variable vacuum reservoir valve 112 is closed, and a strong vacuum is formed on the vacuum side 108 of the air cylinder 102. Thus, the telescoping fork will ride as stiffly as a fixed fork. With mechanical or electronic input the vacuum valve 114 can selectively open or close sequentially to a series of partitioned air reservoirs to add or subtract volume and change the negative pressure, thereby instantly changing the fork preload. The positive pressure side is connected by air lines 122 through pressure reservoir valve 116 to remote pressure reservoir 120. The volume of air cylinder 102 is a fraction of the pressure reservoir volume; accordingly, the internal pressure does not increase greatly even when the piston is fully compressed, and the air spring can work in a linear fashion. Pressure reservoir valve 116 can be actuated at any time during fork movement to increase or reduce pressure volume and to alter the fork rebound or compression characteristics.

(13) Equalization (charge) valve 124 can open to equalize pressure to change the compression and rebound characteristics and “recharge” the vacuum and compression sides on every stroke so that all fork parameters can reset instantly, if desired. In such a configuration, the vacuum and pressure sides work synergistically, combining pressures to increase spring strength. The pressure side works more as a conventional air spring with a relatively constant pressure, and the vacuum works as the variable side that instantly adjusts preload, rebound, compression, and height for varying conditions. Because the vacuum and pressure sides work together, internal pressure is greatly reduced. And note that the vacuum can be controlled to lock the forks in position on smooth terrain and release instantly to respond to impacts.

(14) From the foregoing, it will be seen that the inventive air spring is an active air spring that includes a plurality of air springs, a preferred embodiment being an air bag type spring combined with an air cylinder spring, which modulate internal pressures by varying internal volume through fluid lines and reservoirs, either external or internal only, connected by valves, venting, and self-pressurization to control compression and rebound travel and speed and shock position.