Abstract:
The present invention is a height adjustable pedestal having a gas spring which is easily separated from a furniture component support. The height adjustable pedestal of the present invention can be used in chairs and table. The present invention also provides a method of releasing the tapered upper section of the gas spring from the socket in which it is retained. The method involves no impact forces. The pry lever can be used to apply a force directly on the top of the gas spring cylinder. The invention allows the gas spring to be released simply without the possibility of damage to the gas spring, or other chair component.

Description:
RELATED APPLICATIONS 
     The present application claims the benefit under Title 35, United States Code, Section 119E of the U.S. Provisional Patent Application Ser. No. 60/132,715, filed May 6, 1999 entitled “Gas Spring Quick Release Mechanism and Method”. 
    
    
     BACKGROUND 
     Height adjustable work chairs are used in home, office, education, and industry. These height adjustable chairs typically include a seat that swivels in relation to the base of the chair. The height adjustment is typically obtained from a telescoping spring height adjustment mechanism which is usually a gas spring. This gas spring is a telescoping column that includes a cylinder which includes a pressurized gas such as nitrogen; a piston extending downwardly from the cylinder which supports the cylinder in an elevated position and includes an end which secures the gas spring to the chair base; and a valve located within the cylinder which allows the movement of gas within the cylinder. 
     The upper section of the cylinder is typically tapered and is secured within a tapered socket within a furniture component support mechanism. The furniture component support mechanism is used to support a furniture component such as a chair seat or table top. If the furniture component support mechanism supports a chair seat, the mechanism may be referred to as a chair seat support mechanism. The chair seat support mechanism is also known as the chair tilt mechanism, particularly on chairs with adjustable backrests or chairs having a tilting chair seat. 
     Also included in the furniture component support mechanism is a lever that actuates the valve located in the gas spring. The valve typically includes a button extending from the top of the cylinder. When the button is depressed by the lever the pressurized gas within the cylinder is allowed to move through the valve. The cylinder will descend if a force exceeding gas pressure is applied on the spring or raise the cylinder if no force is applied on the spring. The gas spring may additionally include an air or oil damping mechanism which slows the rate of compression and extension for the gas spring. 
     The gas spring is typically supported in a vertical position between a base and a furniture component support by a vertical stand tube. The stand tube includes a top opening sized so that the cylinder of the gas spring can move vertically and rotationally in relation to the stand tube, yet remain supported by the stand tube regardless of the vertical or rotational position of the cylinder. The stand tube is typically a metal cylinder which includes top and bottom ends. An opening on the top end is included which is sized to accommodate a gas spring cylinder which moves vertically in relation to the stand tube. In some instances a bushing may be disposed within the opening to minimize friction between the gas spring cylinder and the stand tube. The opening serves to both guide the gas spring cylinder as well as to vertically support the gas spring which extends between the chair seat support mechanism and the chair base. 
     The bottom end of the stand tube cylinder typically is tapered for insertion into a base. The tapered bottom end is typically pressed into a tapered socket at the hub or center of the base. The stand tube bottom typically includes an opening through which the distal end of the piston of the gas spring can extend so as to be secured to the bottom of the stand tube. Typically, a clip type fastener is typically used to secure the distal end of the piston of the gas spring to the bottom of the stand tube. 
     During assembly of a chair the tapered upper section of the gas spring cylinder is seated, or secured, into the socket of the gas spring support mechanism. Similarly, during the assembly process the tapered end of the stand tube is seated within the tapered socket of the chair base. 
     During use of the chair, the weight of the chair user is transferred from the chair seat to the chair base through the gas spring/stand tube assembly. Because of this, the tapered upper section of the gas spring cylinder can become very securely pressed into the socket of the gas spring support mechanism. 
     Replacing a damaged gas spring typically involves the replacement of the entire gas spring/stand tube assembly. For this reason, the tapered upper section of the gas spring cylinder must be released from the socket within the gas spring support mechanism. Additionally, the tapered end of the stand tube must also be released from the chair base. This procedure is required to replace a damaged gas spring such as one which has developed excessive play or one which has lost internal gas pressure. 
     Release of the gas spring cylinder from the socket of the gas spring support mechanism typically requires a sharp impact force applied to the chair seat. The force of this impact will eventually cause the release of the tapered upper section of the gas spring cylinder from the socket. This impact force, however is transferred directly through the chair seat, and may in result in damage to the chair seat or another chair component. 
     In the event that the procedure needs to be done in view of the chair owner, the chair owner would watch a hammer wielding technician or sales person disassemble the chair. Multiple hammer blows is hardly the type of treatment that the chair owner expects their expensive chair should receive in this circumstance. 
     For this reason, there is needed a mechanism which assists the removal of the tapered upper section of the gas spring cylinder from the socket within the furniture component support within which it is secured. 
     SUMMARY 
     The present invention is a height adjustable pedestal having a gas spring which is easily separated from a furniture component support. The height adjustable pedestal of the present invention can be used in chairs and tables. The present invention also provides a method of releasing the tapered upper section of the gas spring from the socket in which it is retained. The method involves no impact forces. The pry lever can be used to apply a force directly on the top of the gas spring cylinder. The invention allows the gas spring to be released simply without the possibility of damage to the gas spring, or other chair component. 
     Depending on the type of furniture component support used in the pedestal, access holes which allow for the quick release pry lever to be used are provided within the furniture component support. In some versions of the invention, the access holes provide a surface on which the pry lever can pivot. In other version, a separate pivot surface is provided within the furniture component support. The inclusion of access holes in a chair seat support or other furniture component support does not represent any difficulty for the manufacturer. Because of this, the invention provides significant benefits at little cost to chair assemblies. The invention would work equally well in table assemblies that use telescoping gas spring assemblies. 
     The present invention greatly eases the process of gas spring replacement as it is performed in height adjustable pedestals. Through the use of the present invention, the chair owner or service technician is ensured that no damage to the chair will result from the release of the gas spring from the furniture component support within which it has been disposed. No damaging hammer blows will be applied to the chair seat. 
     These and other features and advantages of the present invention will be apparent upon inspection of the following drawings, description, and claims. 
    
    
     DRAWINGS 
     FIG. 1A-1 shows a side view of a portion of one version of a height adjustable pedestal of the present invention. 
     FIG. 1A-2 shows a side view of a second portion of one version of a height adjustable pedestal of the present invention. 
     FIG. 1B shows a chair seat which could be used with the height adjustable pedestal of the present invention. 
     FIG. 1C shows a table top which could be used with the height adjustable pedestal of the present invention. 
     FIG. 1D show a top view of a furniture component support including a pry lever. 
     FIG. 1E shows a side view of the upper section of a gas spring with a pry lever disposed above the top surface of the gas spring. 
     FIG. 1F shows a side view of a specific furniture component support, a chair tilt mechanism and a pry lever usable with the chair tilt mechanism. 
     FIG. 2A shows a top view of a furniture component support including a second version of the pry lever. 
     FIG. 2B show the second version of the pry lever used with a chair tilt mechanism. 
     FIG. 3A shows a side view of another version of the height adjustable pedestal of the subject invention. 
     FIG. 3B shows a top view of the version of the height adjustable pedestal shown in FIG.  3 A. 
    
    
     DESCRIPTION 
     FIGS. 1A-1 and  1 A- 2  show a side view of one version of a height adjustable pedestal of the present invention. FIG. 1A-1 shows a base  10 , a height adjustable column which is a gas spring/stand tube assembly  20 . The gas spring/stand tube assembly  20  includes a gas spring  30  which is one version of a telescoping spring height adjustment mechanism usable within the height adjustable pedestal. A stand tube  22  is used to support the gas spring  30 . The stand tube is a metal tube and includes a top opening  24  within which the gas spring is supported. The bottom of the stand tube is secured within a socket in the base  10 . The gas spring  30  includes a cylinder  32  and a piston  38  rod which extends downwardly from the cylinder. The bottom of the piston rod is secured to the bottom of the stand tube by a clip  40 . The upper section of the gas spring  30  includes a top surface  34  and a tapered conical portion beneath the top surface. An actuation button  36  extends from the top surface of the gas spring. A resilient spring material in the gas spring cylinder is pressurized gas, typically nitrogen. 
     A furniture component support  50  is shown in partial cross section in FIG. 1A-2. The furniture component support  50  includes a peripheral wall  51 , a top surface  52  on which a furniture component such as a chair seat or table top may be supported. A socket  54  is shown within the furniture component support, and within which the tapered upper section of the gas spring is secured. 
     The furniture component support  50  includes an actuation lever  56  and a pry lever  60 . The actuation lever  56  includes a first end  58  which is disposed above the actuation button  36 . The actuation lever  56  is used to move the valve actuation button  36  by pressing downwardly on the button. The actuation lever serves to unlock the gas spring. Once the gas spring is unlocked, relative movement between the cylinder and piston can occur. The actuation lever toggles between a first position where the button is not depressed and a second position where the button is depressed. The actuation lever is disposed through an opening  57  within the peripheral wall of the furniture component support. 
     A pry lever  60  is disposed on the furniture component support opposite the actuation lever. The pry lever includes a first end  66  and a second end  68 . The pry lever first end  66  presses downwardly on the top surface  34  of the gas spring resulting in the separation of the tapered upper section of the gas spring from the socket  54  of the furniture component support. The pry lever  60  passes through opening  59  disposed within the peripheral wall of the furniture component support. The wall of the opening  59  provides a pivot surface for the pry lever. The pry lever in this version also includes retaining washers  62  and  64  which serve to retain the pry lever in a usable position on the furniture component support. 
     FIG. 1B shows a chair seat  70  and FIG. 1C shows a table top  72  which could be used with the height adjustable pedestal of the present invention. 
     FIG. 1D shows a top view of the furniture component support  50 . The actuation lever  56  is shown having a first end  58  which presses on the actuation button  36  of the gas spring. A pivot  72  serves as the fulcrum and as a retainer for the actuation lever. The pry lever  60  is shown passing through the peripheral wall  51  of the furniture component support. As was previously shown in FIG. 1A, an opening (not shown) is provided within the wall  51  through which the pry lever passes. Retaining washers  62  and  64  serve to retain the pry lever in position within the furniture component support. 
     The pry lever includes a first end  66  which is disposed above the top surface  34  of the gas spring. The second end  68  of the pry lever serves as the end which will be moved upwardly forcing the first end downwardly onto the top surface  34  of the gas spring. The downward force applied by the first end  66  presses on the top surface  34 . This downward force results in the release of the tapered upper portion of the gas spring from the socket  54  within which it is disposed. 
     FIG. 1E shows the upper section of the gas spring including the tapered section  32  of the cylinder, and the cylinder top surface  34 . An actuation button  36  extends upwardly from the top surface  34 . The actuation lever first end  58  is shown in cross section disposed above the actuation button  36 . The pry lever first end  66  is shown disposed above the top surface  34  of the gas spring cylinder. 
     FIG. 1F shows a chair tilt mechanism  150  which includes an opening  152 . The chair tilt mechanism is a specific type of furniture component support, and as its name suggests is used to support a chair seat and a chair backrest. A pry lever  160  is shown prior to assembly into the chair tilt mechanism where the pry lever can be used to release the gas spring from a socket (not shown) within the chair tilt mechanism  150 . Although the socket has not been shown in this figure, such chair tilt mechanism are commonly part of an assembly that includes a socket. The sockets within these chair tilt mechanisms are typically integrated directly into the chair tilt mechanism. Alternatively, the chair tilt mechanism could straddle a furniture component support such as been shown in FIGS.  1 A and  1 D. In either case, the opening  152  may provide a pivot surface for the pry lever  160  or a pivot surface other than the opening could be provided. The pry lever retaining washers  162  and  164  are also shown prior to assembly. 
     FIG. 2A shown a modified version of the invention. As shown, this version includes a furniture component support  250 , which includes a peripheral wall  251 . The peripheral wall includes an opening  259  through which a pry lever  260  has been inserted. The pry lever  260  includes a forked first end having ends  266 A and  266 B, and a second end  268 . The forked ends contact the top surface  234  of the gas spring at opposite sides of the actuation button  236 . The pry lever  260  pivots about a pivot surface  274  horizontally disposed within the furniture component support. The upper section of the gas spring can be released from the socket  254  by moving the second end of the pry lever upwardly. This causes the pivoting of the pry lever about the pivot surface, resulting in the forked ends pressing downwardly on the top surface of the gas spring. 
     FIG. 2B shows another version of the invention where a chair tilt mechanism  290  includes two openings  292  and  294 . In this version the two opening themselves provide the pivot surface for the pry lever  260 . The pry lever includes forked ends  266 A and  266 B. The forked ends of the pry lever again are used to press downwardly on the gas spring  230  causing the release of the gas spring from a socket (not shown in this figure). 
     The pry lever as is shown in FIG. 2B is not permanently assembled into the chair tilt mechanism. It is understood that the previous versions of the invention which used retaining washers to retain the pry lever on the furniture component support could have omitted the retaining washers. Accordingly, there is no requirement of the present invention to remain permanently attached to the furniture component support. However, as the pry lever does not represent a significant additional cost to the furniture component support, it is felt that permanently mounting the pry lever in many cases is desirable. 
     Although gas springs have been described throughout this description, it is understood that telescoping spring height adjustment mechanisms that include spring materials other than pressurized gas could also have been used. Metallic coil springs are also found in these devices. 
     FIGS. 3A and 3B show another version of the invention. In this version, a base  210  includes a tapered center socket  212 . A channel  214  extends horizontally through the base into the center socket. The bottom tapered portion of a stand tube  222  is disposed within the socket. The stand tube includes an opening  224 . The top of the opening  224  extends to a vertical position below the top of the channel  214 . A pry lever  230  is inserted through the channel and through the opening into the interior of the stand tube. Pressing downward on the pry lever causes the pry lever to pivot about the bottom surface of the channel. Upon pivoting, the pry lever will push upwardly on the top surface of the opening within the stand tube. The pry lever needs to move the stand tube vertically a very small distance to release the stand tube from the socket within the base. 
     It is understood that various other modifications and changes of form or detail could readily be made without departing from the spirit of the invention. It is intended that the invention be not limited to the exact form and detail herein shown and described, nor to anything less than the whole of the invention disclosed and hereinafter claimed.