Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
  • F04B53/16—Casings; Cylinders; Cylinder liners or heads; Fluid connections
  • F04B53/162—Adaptations of cylinders
  • F04B53/164—Stoffing boxes

Definitions

• This invention relates to seals for high pressure fluid pumps having reciprocating plungers.
• seal designs for use in such an environment include an extrusion resistant seal that seals against the plunger and is supported by a back-up ring.
• the back-up ring and seal may be supported by a seal carrier and may be biased toward the seal carrier with a coil spring that encircles the plunger.
• the spring may be held in place against the seal with a collar that has a bore through which the plunger passes and that has a flange encircling one end of the spring.
• the present invention is directed toward methods and apparatuses for sealing components of a high pressure pump having a reciprocating plunger.
• the apparatus may include a cylinder having a cylinder wall with at least one opening, an elongated plunger extending through the opening, and a spring disposed about the plunger.
• the spring may have an inner surface facing toward the plunger and an outer surface facing away from the plunger.
• the assembly may further comprise a seal having a sealing surface that seals against the plunger and an engaging surface that engages at least one of the inner and outer surfaces of the spring to restrict lateral motion of the spring relative to the plunger.
• the seal may have several shapes.
• the seal may include a continuous flange that extends around to the circumference of the spring.
• the seal may include a plurality of spaced-apart projections that engage the spring.
• the flange may have a first engaging surface adjacent the inner surface of the spring and a second engagement surface adjacent the outer surface of the spring.
• the present invention is also directed toward a method for restricting motion of a spring disposed about a plunger of a high pressure pump.
• the method may comprise sealably engaging a seal with the plunger, engaging the seal with at least one of the inner surface and the outer surface of the spring toward one end of the spring, and restricting lateral motion of the spring relative to the plunger.
• the method may include engaging both the inner and outer surfaces of the spring, and may further include engaging an opposite end of the spring.
• the method may include engaging a portion of one coil of the spring corresponding to half a diameter of a filament that comprises the spring, or may include engaging more than one coil of the spring.
• Figure 1 is a partial cross-sectional plan view of a pump assembly having a seal carrier and seal in accordance with an embodiment of the invention.
• Figure 2 is an enlarged partial cross-sectional plan view of the seal and seal carrier illustrated in Figure 1.
• Figure 3 is a detailed cross-sectional plan view of the seal carrier illustrated in Figures 1 and 2.
• Figure 4 is a partial cross-sectional plan view of a seal assembly having a seal that engages an outer surface of a spring in accordance with another embodiment of the invention.
• Figure 5 is a partial cross-sectional plan view of a seal assembly having a seal that engages an inner surface of a spring in accordance with still another embodiment of the invention.
• Figure 6 is a partial cross-sectional plan view of a seal assembly having a seal that engages inner and outer surfaces of a spring in accordance with yet another embodiment of the invention.
• Figure 7 is an isometric view of a seal having projections in accordance with still another embodiment of the invention.
• Figure 8 is a partial cross-sectional plan view of a seal assembly having a back-up ring in accordance with yet another embodiment of the invention.
• a high pressure fluid seal assembly 10 is provided in accordance with one embodiment of the present invention, as illustrated in Figure 1.
• the seal assembly 10 is for use in a high pressure pump assembly 22 having a reciprocating plunger 14 coupled to a drive mechanism 26.
• the plunger 14 reciprocates in a high pressure cylinder 24.
• the seal assembly 10 is positioned adjacent the plunger 14 at one end of the cylinder 24 to restrict and/or prevent the leakage of high pressure fluid from a high pressure region 23 within the high pressure cylinder 24.
• a check valve 30 at the opposite end of the cylinder 24 includes a plurality of inlet ports 31, an outlet port 32, and a poppet 33 that seals the inlet ports.
• the check valve 30 directs fluid through the inlet ports 31 and into the cylinder 24 when the plunger 14 partially withdraws from the cylinder during an intake stroke.
• the check valve 30 directs pressurized fluid out of the cylinder 24 through the outlet port 32 when the plunger 14 moves into the cylinder during a pressure stroke.
• a collar or retainer 50 may be located within the cylinder 24 between the seal assembly 10 and the check valve 30 to reduce the volume within the cylinder and thereby increase the pressure generated with each pressure stroke of the plunger 14.
• the collar 50 also applies a biasing force to the poppets 33 via a poppet spring 34 and to the components of the seal assembly 10 via a seal spring 60, as will be discussed in greater detail below.
• the seal assembly 10 includes a seal carrier 12 having a bore 13 through which the reciprocating plunger 14 passes.
• the seal carrier 12 has a first annular groove 15 in which an annular seal 17 is positioned.
• the annular seal 17 has a sealing surface 55 that seals against the plunger 14.
• An annular elastomeric seal 25 is provided around the outer circumference of annular seal 17, to energize the annular seal 17 during the start of the pressure stroke.
• the seal spring 60 engages the annular seal 17 and urges it toward the first annular groove 15 to restrict motion of the annular seal 17 away from the seal carrier 12.
• the seal carrier 12 has an integral, annular guidance bearing 19 that is positioned in a second annular groove 16 within the bore 13. The second annular groove 16 and the guidance bearing 19 positioned therein are axially spaced apart from the first annular groove 15 and the annular seal 17 contained therein.
• Figure 3 is a detailed cross-sectional view of the seal carrier 12 and the guidance bearing 19 shown in Figure 2.
• an inner diameter 20 of the guidance bearing 19 is smaller than an inner diameter 21 of the seal carrier bore 13 in a region 11 between the seal 17 ( Figure 2) and the guidance bearing 19.
• the inner diameter 20 is .0005-.0015 inch smaller than the inner diameter 21.
• an end region 18 ( Figure 2) of the annular seal 17 is supported by region 11 of the seal carrier 12; however, the region 11 of seal carrier 12 is not in contact with the plunger 14, because the diameter 21 of the bore 13 in region 11 is greater than the inner diameter 20 of the guidance bearing 19.
• An embodiment of the seal assembly 10 shown in Figures 1-3 therefore supports the seal 17 directly with the seal carrier 12, eliminating the need for a back-up ring.
• the integral guidance bearing 19 prevents the plunger 14 from contacting the seal carrier 12, thereby reducing frictional heating in the vicinity of the seal 17, which in turn extends the life of the seal.
• the materials for the components are selected to minimize the friction between the plunger 14 and the guidance bearing 19 and between the plunger 14 and the seal 17.
• the plunger 14 is made of partially stabilized zirconia ceramic
• the guidance bearing 19 is made of a resin impregnated graphite
• the seal 17 is made of an ultra-high molecular weight polyethylene.
• a variety of materials may be used, and the materials selected for one component may depend on the materials selected for another component.
• the seal assembly 10 is preferably manufactured by pressing the guidance bearing 19 into the seal carrier 12, and machining the bore 13 through the guidance bearing and through region 11 of the seal carrier in the same machining setup.
• the inner diameter of the bore 13 in region 11 is machined slightly larger than the inner diameter 20 of the bore through the guidance bearing.
• the seal 17 may be biased toward the seal carrier 12 by the seal spring 60, as discussed above.
• the seal spring 60 may include a wire filament coiled about the plunger 14 to form a plurality of coils 64 that encircle the plunger. Each coil 64 may have an inner surface 61 facing the plunger 14 and an outer surface 62 facing away from the plunger. In other embodiments, the seal spring 60 may have other shapes that also bias the annular seal 17 toward the seal carrier 12.
• the seal springs may flex transverse to the axis of the plunger 14 and rub against either the plunger or the collar 50. Accordingly, the seal springs may wear down and may place an uneven load on the seals against which the seal springs bear, causing the seals to leak. Alternatively, the seal springs may cause either the collar 50 or the plunger 14 to wear, reducing the useful life of these components.
• the annular seal 17 may include a body 28 and an annular flange portion 54.
• the flange portion 54 extends away from the body concentric with the seal spring 60, the plunger 14 and the annular seal 17, and engages the outer surface 62 of the seal spring.
• the flange portion 54 may have an engaging surface 56 that engages two of the coils 64 of the seal spring 60.
• the engaging surface 56 may be curved to correspond to the curved shape of the coils 64.
• the engaging surface 56 may engage more or fewer coils 64 and/or other portions of the seal spring 60, as is discussed in greater detail below with reference to Figures 4-9.
• the engaging surface 56 may engage seal springs 60 having shapes other than the axisymmetric coiled shape shown in Figure 2.
• An advantage of the seal 17 and the flange portion 54 is that they may engage the outer surface 62 of the seal spring 60 and restrict motion of the seal spring transverse to the axis of the plunger 14. Accordingly, the seal spring 60 may be less likely to contact the plunger 14 and/or the collar 50, potentially increasing the life of the plunger, the collar, and the seal spring. Furthermore, by reducing friction between the seal spring 60, the plunger 14, and the collar 50, the heat generated in the cylinder 24 may be reduced, thereby increasing the life of the seal 17.
• the collar 50 may include a flange portion 54a having an engaging surface 56a.
• the engaging surface 56a may be positioned to engage the outer surface 62 of the seal spring 60, opposite the portion of the seal spring engaged by the engaging surface 56 of the seal 17.
• Figure 4 is a partial cross-sectional plan view of a seal assembly 10 having a seal 117 with a shortened annular flange 154 in accordance with another embodiment of the invention.
• the flange 154 has an engaging surface 156 that engages a portion of the seal spring 60 approximately equal to half a diameter D of the filament comprising the seal spring.
• the flange 154 may engage a greater or lesser portion of the seal spring 60, so long as it engages enough of the seal spring to restrict and/or prevent lateral motion of the seal spring relative to the plunger 14.
• An advantage of the seal 117 when compared to the seal 17 shown in Figure 2 is that it may require less material to manufacture.
• Figure 5 is a partial cross-sectional plan view of a seal assembly 10 having a seal 217 with an annular flange 254 adjacent the plunger 14.
• the seal 217 may therefore sealably engage a larger portion of the plunger 14, and may accordingly provide a better seal with the plunger.
• the flange 254 has an engaging surface 256 that engages the inner surface 261 of a seal spring 260 to restrict and/or prevent lateral motion of the seal spring 260 relative to the plunger 14 and the collar 50.
• the engaging surface 256 may engage a single coil 264 of the seal spring 260, or may engage a greater or lesser portion of the spring, as discussed above with respect to Figures 2 and 4.
• FIG. 5 is a partial cross-sectional plan view of a seal assembly 10 having a seal 317 with an inner flange 354a spaced apart from an outer flange 354b.
• the inner flange 354a has an engaging surface 356a that engages the inner surface 61 of the seal spring 60
• the outer flange 354b has an engaging surface 356b that engages the outer surface 62 of the spring. Accordingly, the seal 317 may further prevent lateral motion of the spring 60 relative to the plunger 14.
• Figure 7 is an isometric view of a seal 517 having a plurality of engaging members 554 spaced around the circumference of a bore 557.
• the bore 557 may be sized to slidably engage the plunger 14 (Figure 2) and the engaging members 554 may include engaging surfaces 556 positioned to engage the seal spring 60 ( Figure 2).
• the engaging surfaces 556 are configured to engage the outer surface 62 ( Figure 2) of the seal spring 60, and in other embodiments, the engaging surfaces may be configured to engage the inner surface 61 ( Figure 2) of the seal spring.
• the spring guide 517 may include seven engaging members 554 and may include a greater or lesser number of engaging members in other embodiments.
• Figure 8 is a partial cross-sectional plan view of a seal assembly 10 that includes a seal carrier 612 retaining an annular seal 617 and a back-up ring 634.
• the back-up ring 634 may support the annular seal 617 relative to the plunger 14.
• the annular seal 617 may include a flange portion 654 that engages the outer surface 62 of the seal spring 60.
• the flange portion 654 may be configured to engage the inner surface 61 of the seal spring 60 in a manner similar to that shown in Figure 5, or both the inner and the outer surfaces 61, 62 in a manner similar to that shown in Figure 6.
• annular seal 617 may engage enough of the seal spring 60 to restrict and/or prevent contact between the seal spring 60 and one or both of the collar 50 and the plunger 14.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Details Of Reciprocating Pumps (AREA)
• Sealing Devices (AREA)
• Mechanical Sealing (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

Applications Claiming Priority (5)

Publications (2)

Family

ID=26752562

Family Applications (1)

Country Status (9)

Families Citing this family (6)

Family Cites Families (3)

• 1998
  • 1998-09-17 DE DE69821125T patent/DE69821125T2/de not_active Expired - Fee Related
  • 1998-09-17 CA CA002303103A patent/CA2303103C/en not_active Expired - Fee Related
  • 1998-09-17 JP JP2000512008A patent/JP4409761B2/ja not_active Expired - Lifetime
  • 1998-09-17 EP EP98948308A patent/EP1015768B1/de not_active Expired - Lifetime
  • 1998-09-17 ES ES98948308T patent/ES2214731T3/es not_active Expired - Lifetime
  • 1998-09-17 AU AU94904/98A patent/AU9490498A/en not_active Abandoned
  • 1998-09-17 AT AT98948308T patent/ATE257910T1/de not_active IP Right Cessation
  • 1998-09-17 WO PCT/US1998/019410 patent/WO1999014500A1/en not_active Ceased
  • 1998-09-18 TW TW087115582A patent/TW490535B/zh not_active IP Right Cessation

Non-Patent Citations (1)

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