Plunger with annular exterior seals and method of installing annular seals on an exterior surface of a plunger

A method of installing annular seals on a plunger. A first step involves positioning an annular seal on a seal installation tool adapted to hold the annular seal in an expanded state. A second step involves positioning the annular seal so that the annular seal overlies a body of a plunger. A third step involves transferring the annular seal from the seal installation tool to a seal groove in the body of the plunger.

This application claims priority from Canadian Application Serial No. 2,515,134 filed Jul. 26, 2005.

FIELD OF THE INVENTION

The present invention relates to a plunger with annular exterior seals and a method of installing annular seals on an exterior surface of a plunger.

BACKGROUND OF THE INVENTION

Gas lift plungers have a number of annular exterior seals. A joint is positioned at each seal location to allow the disassembly of the plunger, in order to facilitate installation of the annular seals. Each joint is a potential failure point for the plunger.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided a plunger, which has a cylindrical body. All or at least a portion of the body is in one piece with more than one circumferential exterior seal groove. Replaceable annular seals are positioned in selected ones of the seal grooves.

According to another aspect of the present invention there is provided a method of installing annular seals on a plunger. A first step involves positioning an annular seal on a seal installation tool adapted to hold the annular seal in an expanded state. A second step involves positioning the annular seal so that the annular seal overlies a body of a plunger. A third step involves transferring the annular seal from the seal installation tool to a seal groove in the body of the plunger.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment, a plunger generally identified by reference numeral10, will now be described with reference toFIG. 1.

Plunger10has a cylindrical body12. Body12is machined in one piece with numerous circumferential exterior seal grooves14. Replaceable annular seals16made from elastomer are positioned in seal grooves14. As depicted, annular seals16are positioned in every other seal groove14. Plunger10has the distinct advantage of having no joints. It will be appreciated that it not essential that there be no joints. Benefits could be gained by simply reducing the number of joints. This is done by placing more than one of seal grooves14on each portion of more than one portion of body12.

It would not be possible to make plunger10, unless some method were developed for installing annular seals16onto a one piece body12.

Referring toFIG. 2 through 6, there will now be described a preferred method of installing annular seals16. Referring toFIG. 4, annular seal16is positioned on a seal installation tool20. Seal installation tool20is adapted to hold annular seal16in an expanded state. Seal installation tool20can take a number of forms. The form selected for illustration is a sleeve-form body22with an exterior surface24on which is positioned a seal seat26. Referring toFIG. 5, body22is positioned so that annular seal16overlies body12of plunger10. Referring toFIG. 6, annular seal16is then transferred from seal installation tool20to one of seal grooves14on body12of plunger10.

It will be appreciated that body22of seal installation tool20need not be in the form of a sleeve. It will also be appreciated that body22need not overlie plunger10, as long as annular seal16does. It will also be appreciated that seal seat26can be discontinuous, as annular seal16could be just as effectively held in an expanded condition by a plurality of fingers arranged in a ring.

Referring toFIG. 2, a seal expanding member30has been developed for use in expanding annular seal16. Seal expanding member30has a truncated conical body32. It will be appreciated that body32need not be truncated, but only the lower portion of body32is needed to perform the expanding operation. An upper portion of body32, does not serve a useful function if its outer diameter is smaller than the inner diameter of annular seal16. It will be appreciated that the conical form is merely a convenient form of inclined plane shape to accomplish the desired objective. Other forms of inclined plane could be used to expand annular seal16onto seal seat26. Referring toFIG. 3, once annular seal16is expanded it is transferred from seal expanding member30to seal seat26of seal installation tool20in preparation for installation, as described above.