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Title:
DEVICES FOR SEALING HIGH PRESSURE AND ULTRAHIGH PRESSURE FLUID SYSTEMS
Document Type and Number:
WIPO Patent Application WO/2013/109474
Kind Code:
A1
Abstract:
A seal assembly is provided which is operable with a pump having a plunger configured to reciprocate within a cylinder thereof along a longitudinal axis to generate pressurized fluid during operation. The seal assembly includes a seal carrier including an external surface configured to sealingly mate with the cylinder of the pump when the seal carrier is installed in a mouth of the cylinder and urged toward the cylinder by a compressive force and further includes a bearing received and circumferentially surrounded by the seal carrier. The bearing and seal carrier include features designed to enable prolonged component life, including in particular at ultrahigh high pressures.

Inventors:
HOPKINS JORDAN J (US)
Application Number:
PCT/US2013/021265
Publication Date:
July 25, 2013
Filing Date:
January 11, 2013
Export Citation:
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Assignee:
FLOW INT CORP (US)
International Classes:
F04B53/02; F04B37/12; F04B53/16; F16J15/48; F16J15/56
Foreign References:
US3877707A1975-04-15
US5493954A1996-02-27
US4470607A1984-09-11
US7247006B22007-07-24
EP0391487A21990-10-10
US4474382A1984-10-02
US6623259B12003-09-23
US4878815A1989-11-07
US6086070A2000-07-11
US6802541B22004-10-12
US7247006B22007-07-24
US7568424B22009-08-04
US6802541B22004-10-12
Attorney, Agent or Firm:
LINFORD, Lorraine et al. (Suite 5400701 Fifth Avenu, Seattle WA, US)
Download PDF:
Claims:
CLAIMS

1 . A seal assembly operable with a pump having a plunger configured to reciprocate within a cylinder thereof along a longitudinal axis to generate pressurized fluid at or above 40,000 psi during operation, the seal assembly comprising:

a seal carrier including an external surface configured to sealingly mate with the cylinder of the pump when the seal carrier is installed in a mouth of the cylinder and urged toward the cylinder by a compressive force, and the seal carrier including a seal recess to receive an annular seal through which the plunger reciprocates during operation; and

a bearing received and circumferentially surrounded by the seal carrier at a position adjacent the seal recess, the bearing including a first portion having an inner surface of a first diameter and a second portion having an inner surface of a second diameter greater than the first diameter, the first diameter sized such that when the seal carrier receives the annular seal during operation the inner surface of the first portion of the bearing is generally coextensively aligned with an inner surface of the annular seal, and the second diameter sized such that at least a portion of the inner surface of the second portion of the bearing contacts the plunger during at least a portion of operation.

2. The seal assembly of claim 1 wherein the inner surface of the first portion of the bearing extends in a longitudinal direction less than twenty percent of an overall height of the bearing.

3. The seal assembly of claim 1 wherein the inner surface of the first portion of the bearing extends in a longitudinal direction less than ten percent of an overall height of the bearing.

4. The seal assembly of claim 1 wherein the first diameter of the inner surface of the first portion of the bearing is at least 0.001 inch less than the second diameter of the inner surface of the second portion of the bearing.

5. The seal assembly of claim 1 wherein the first diameter of the inner surface of the first portion of the bearing is between 0.001 inch and 0.025 inch less than the second diameter of the inner surface of the second portion of the bearing.

6. The seal assembly of claim 1 wherein the bearing includes a third portion between the first portion and the second portion which has a tapered inner surface.

7. The seal assembly of claim 1 wherein a central portion of the bearing has a wall thickness which is less than a respective thickness of each of opposing terminal ends of the bearing.

8. The seal assembly of claim 1 wherein the second diameter of the second portion of the bearing is sized relative to the first diameter of the first portion of the bearing to maintain contact between the second portion of the bearing and the plunger at least during periods of operation characterized by high system pressure.

9. The seal assembly of claim 1 wherein the second diameter of the second portion of the bearing is sized relative to the first diameter of the first portion of the bearing to substantially reduce contact stresses arising from contact of the second portion of the bearing with the plunger during operation.

10. The seal assembly of claim 1 , further comprising: the annular seal received in the seal recess of the seal carrier.

1 1 . The seal assembly of claim 1 wherein the seal recess of the seal carrier is configured to captively receive the annular seal and retain the annular seal in an abutting relationship with the first portion of the bearing.

12. The seal assembly of claim 1 wherein the bearing includes a tapered section that increases in wall thickness with increasing distance from the seal recess in a direction parallel to a central axis of the bearing.

13. The seal assembly of claim 12 wherein the tapered section increases continuously in wall thickness.

14. The seal assembly of claim 12 wherein the tapered section includes a step where the first portion of the bearing transitions to the second portion of the bearing.

15. A seal assembly operable with a pump having a plunger configured to reciprocate within a cylinder thereof along a longitudinal axis to generate pressurized fluid at or above 40,000 psi during operation, the seal assembly comprising:

a seal carrier including an external surface configured to sealingly mate with the cylinder of the pump when the seal carrier is installed in a mouth of the cylinder and urged toward the cylinder by a compressive force, and the seal carrier including a seal recess to receive an annular seal through which the plunger reciprocates during operation; and

a bearing received and circumferentially surrounded by the seal carrier at a position adjacent the seal recess, the bearing including a central aperture which defines a central axis and the bearing having a tapered section that increases in wall thickness with increasing distance from the seal recess in a direction parallel to the central axis.

16. The seal assembly of claim 15 wherein the central aperture has a constant diameter.

17. The seal assembly of claim 15 wherein the central aperture includes two or more sections each having different diameters.

18. The seal assembly of claim 15 wherein the bearing further includes a terminal section having a constant wall thickness, the wall thickness of the terminal section being thinner than any other portion of the bearing.

19. The seal assembly of claim 15 wherein the bearing further includes a terminal section defined by a constant wall thickness, the terminal section of the bearing positioned to abut the annular seal when the annular seal is received in the seal recess.

20. The seal assembly of claim 15 wherein a longitudinal length of the tapered section of the bearing is greater than thirty percent of an overall height of the bearing.

21 . The seal assembly of claim 15 wherein the tapered section has a draft angle between about five degrees and about twenty- five degrees.

22. The seal assembly of claim 21 wherein the tapered section has a draft angle between about ten degrees and about twenty degrees.

23. The seal assembly of claim 15 wherein the bearing includes a shoulder at one end of the tapered section to mate with a corresponding shoulder of the seal carrier.

24. The seal assembly of claim 15 wherein the tapered section is interposed between two opposing sections each having a uniform wall thickness.

25. The seal assembly of claim 24 wherein a wall thickness of one end of the bearing is less than about one-third of a wall thickness of the opposing end of the bearing and wherein a wall thickness of the tapered section varies therebetween.

26. The seal assembly of claim 15 wherein, when the seal carrier sealingly mates with the cylinder during operation, a reference line normal to a tangential contact angle defined by contact between the seal carrier and the cylinder passes through the tapered section of the bearing.

27. The seal assembly of claim 15, further comprising: the annular seal received in the seal recess of the seal carrier.

28. The seal assembly of claim 15 wherein the seal recess of the seal carrier is configured to captively receive the annular seal and retain the annular seal in an abutting relationship with an end of the bearing.

29. A pump having a plunger configured to reciprocate along a longitudinal axis within a cylinder thereof to generate pressurized fluid at or above 40,000 psi, the pump including a seal assembly of one of the preceding claims installed in a mouth of the cylinder.

Description:
DEVICES FOR SEALING

HIGH PRESSURE AND ULTRAHIGH PRESSURE FLUID SYSTEMS

BACKGROUND

Technical Field

The present disclosure relates to high pressure and ultrahigh pressure fluid systems, and in particular, to components and assemblies for sealing high pressure and ultrahigh pressure systems, such as ultrahigh pressure pumps.

Description of the Related Art

High pressure pumps and ultrahigh pressure pumps draw a volume of fluid into the pump on an intake stroke of a plunger, and on a pressure stroke of the plunger, pressurize the volume of fluid to a desired pressure, up to and beyond 87,000 psi and including over 100,000 psi. The pressurized fluid flows through a check valve body to an outlet check valve. If the pressure of the fluid is greater than a biasing force provided by high pressure fluid in an outlet area acting on a downstream end of the outlet check valve, the high pressure fluid overcomes the biasing force, and passes through the outlet check valve to the outlet area. Typically, a pump has multiple cylinders, and pressurized fluid from the outlet area of each pump is collected in an accumulator. High pressure fluid collected in this manner is then selectively used to perform a desired function, such as cutting or cleaning. Such pumps are manufactured, for example, by the assignee of the present invention, Flow International Corporation of Kent, Washington. As the plunger reciprocates within a bore of the pump cylinder, the plunger passes through a dynamic seal assembly that prevents pressurized fluid in the cylinder from flowing past the plunger into the pump. Example dynamic seal assemblies are shown in U.S. Patent Nos. 6,086,070; 6,802,541 ; 7,247,006 and 7,568,424, which are incorporated herein by reference in their entireties, and which are assigned to the assignee of the present application, Flow International Corporation.

While known dynamic seal assemblies provide suitable sealing arrangements under many operating conditions, Applicants believe it would be desirable in many situations to further optimize the operation of high pressure pumps and ultrahigh pressure pumps and increase the longevity of components thereof, particularly for operation at ultrahigh pressures of up to and beyond 87,000 psi, including pressures above 100,000 psi. Increasing the longevity of pump components will reduce the frequency of component replacement and as a result will reduce machine down time and lost productivity. More robust, long- lasting components also enhance operational safety of the host pumps.

BRIEF SUMMARY

The seal assemblies and components thereof described herein are particularly well adapted for use in high pressure and ultrahigh pressure pumps to seal around a reciprocating plunger in a reliable and robust manner.

According to one embodiment, a seal assembly for a high pressure pump may be summarized as including a seal carrier having an external surface configured to sealingly mate with a cylinder of the pump when the seal carrier is installed in a mouth of the cylinder and urged toward the cylinder by a compressive force, and the seal carrier having a seal recess to receive an annular seal through which the plunger reciprocates during operation; and a bearing received and circumferentially surrounded by the seal carrier at a position adjacent the seal recess. The bearing includes a first portion having an inner surface of a first diameter and a second portion having an inner surface of a second diameter greater than the first diameter, the first diameter sized such that when the seal carrier receives the annular seal during operation the inner surface of the first portion of the bearing is generally coextensively aligned with an inner surface of the annular seal, and the second diameter sized such that at least a portion of the inner surface of the second portion of the bearing contacts the plunger during at least a portion of operation. The bearing may also include a tapered section that increases in wall thickness with increasing distance from the seal recess in a direction parallel to a central axis of the bearing. The tapered section may increase continuously in wall thickness or may include a step where the first portion of the bearing transitions to the second portion of the bearing.

According to another embodiment, a seal assembly for a high pressure pump may be summarized as including a seal carrier having an external surface configured to sealingly mate with the cylinder of the pump when the seal carrier is installed in a mouth of the cylinder and urged toward the cylinder by a compressive force, and the seal carrier having a seal recess to receive an annular seal through which the plunger reciprocates during operation; and a bearing received and circumferentially surrounded by the seal carrier at a position adjacent the seal recess. The bearing includes a central aperture which defines a central axis and has a tapered section that increases in wall thickness with increasing distance from the seal recess in a direction parallel to the central axis. The central aperture may have a constant diameter or may include two or more sections each having different diameters.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Figure 1 is a partial cross-sectional plan view of a conventional ultrahigh pressure pump incorporating a prior art dynamic seal assembly.

Figure 2 is an enlarged partial cross-sectional plan view of a conventional ultrahigh pressure pump incorporating another prior art dynamic seal assembly.

Figure 3 is an isometric view of a dynamic seal assembly usable within ultrahigh pressure pumps, according to one embodiment.

Figure 4 is an enlarged cross-sectional isometric view of the dynamic seal assembly of Figure 3.

Figure 5 is an enlarged cross-sectional elevational view of the dynamic seal assembly of Figure 3. Figure 6 is an enlarged cross-sectional isometric view of a dynamic seal assembly according to another embodiment.

Figure 7 is an enlarged cross-sectional elevational view of the dynamic seal assembly of Figure 6. DETAILED DESCRIPTION

In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one of ordinary skill in the relevant art will recognize that

embodiments may be practiced without one or more of these specific details. In other instances, well-known structures associated with high pressure and ultrahigh pressure fluid systems, including high pressure and ultrahigh pressure pumps, and components thereof, may not be shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments.

Unless the context requires otherwise, throughout the specification and claims which follow, the word "comprise" and variations thereof, such as, "comprises" and "comprising" are to be construed in an open, inclusive sense, that is as "including, but not limited to."

Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the content clearly dictates otherwise. It should also be noted that the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise. In many situations, it would be desirable to optimize an operation of high pressure and ultrahigh pressure fluid pumps at high and ultrahigh pressures and improve longevity of components thereof. For example, an ultrahigh pressure intensifier pump, such as those manufactured by Flow International Corporation, may be used for a variety of applications, such as supplying high pressure fluid to an abrasive waterjet cutting head. While the below discussion will use an ultrahigh pressure intensifier as an example, it will be understood that embodiments of the present invention may have application in sealing an axially reciprocating plunger of any pump, including those capable of supplying pressurized fluid in excess of 100,000 psi.

By way of further background, Figure 1 shows an ultrahigh pressure fluid system 10, such as an intensifier pump, which is provided with a plunger 12 that reciprocates within a bore 13 of a pump cylinder 1 1 during operation. The plunger 12 draws a volume of fluid from a source of fluid 18 into the bore 13 via an inlet valve 16 provided in check valve body 14 on an intake stroke of the plunger illustrated by the direction arrow marked 17. On a pressure stroke 19, the plunger 12 pressurizes the volume of fluid, the pressurized fluid flowing through the check valve body 14 to the outlet check valve 37. If the pressure of the pressurized fluid is sufficiently high to overcome the biasing force on the outlet check valve 37, the pressurized fluid passes through the outlet check valve 37 to an outlet area 20, after which the pressurized fluid is collected in an accumulator and used in any desired manner, as is known in the art.

As further shown in Figure 1 , the plunger 12 reciprocates through a sealing assembly 21 . The sealing assembly 21 includes a seal 22, which is preferably made of a plastic material, such as, for example, ultrahigh molecular weight polyethylene. The annular seal 22 is provided with a bore through which the plunger 12 reciprocates during operation. A bearing 24, is positioned adjacent and/or contiguous the seal 22, and is also provided with a bore through which the plunger 12 reciprocates during operation. The material of the bearing 24 is preferably chosen to be a material which can ride along the plunger 12 while the plunger 12 is in motion with relatively minimal friction. While the bearing 24 and plunger 12 may be made of any appropriately cooperative materials, the bearing 24 can be made of a high strength bronze, aluminum or copper alloy, and the plunger can be made from a ceramic material, such as partially stabilized Zirconia (PSZ).

A seal carrier 26 surrounds a circumference of the bearing 24 and captures the seal 22. Although the seal carrier 26 may be made of a variety of materials, it is preferably made of stainless steel. During operation, the seal carrier 26 is subjected to a compressive force that is sufficiently high to circumferentially collapse the seal carrier 26 in a radial direction against the bearing 24. This collapse of the seal carrier 26 against the bearing 24 causes an inner surface of the bore of the bearing 24 to contact with an outer surface of the plunger 12.

With continued reference to Figure 1 , the compressive force on the seal carrier 26 may be achieved by tightening tie rods 29 of the system that load the cylinder 1 1 via end cap 38 seating the check valve body 14 against a first end 15 of cylinder 1 1 . The cylinder 1 1 may be seated against the seal carrier 26 in such a way as to form a static seal along a tangential sealing area 32, as described in more detail in U.S. Patent No. 6,802,541 . The compressive force applied via the tie rods 29 and the cylinder 1 1 on the seal carrier 26 may be sufficiently great and applied in such a manner given the geometry of the system to collapse the seal carrier 26 and bearing 24 onto the plunger 12.

Accordingly, the bearing 24 may apply compressive stress on the plunger 12 as the plunger 12 reciprocates through the bearing 24 during operation. As the pressure within the cylinder 1 1 cycles between atmospheric pressure and high or ultrahigh pressures, the cylinder 1 1 , seal carrier 26 and other components may expand and contract at different rates and the seal carrier 26 and bearing 24 may be urged into contact with the plunger 12 with varying degree.

Accordingly, stresses arising from the interaction of the bearing 24 and the plunger 12 may vary over the course of operation. Further, the amount of deformation of the seal carrier 26 can vary based on the angles of the surfaces of the cylinder 1 1 and seal carrier 26 that form the tangential sealing area 32, the selected materials, as well as the amount of assembly loading, for example, as may be achieved through tightening of tie rods 29. While tie rods 29 are described and illustrated in the present disclosure, it will be understood that the loading at assembly may be accomplished in any available manner.

Figure 2 illustrates a portion of an ultrahigh pressure fluid system 50 including another known seal carrier 52 having an inner surface 54 proximate the plunger 12 and an outer surface 56 opposing the inner surface 54 along a lateral axis substantially perpendicular to a longitudinal axis 58 along which the plunger 12 may reciprocate. As illustrated in Figure 2, a first portion 60 of the inner surface 54 is configured to circumferentially surround and captively receive a seal 62. For example, a first indent 61 formed in the first portion 60 captively receives the seal 62. A second portion 64 of the inner surface 54 is configured to circumferentially surround a bearing 66, which is positioned adjacent and/or contiguous the seal 62. The inner surface 54 of the seal carrier 52 may also include a second indent 68 circumferentially and axially surrounding an o-ring 70. In some embodiments, the second indent 68 is formed in the first indent 61 , laterally interposing the o-ring 70 between the seal 62 and the seal carrier 52. The seal carrier 52 of the ultrahigh pressure fluid system 50 may substantially prevent any potential longitudinal displacement of the seal 62 and the o-ring 70.

The seal carrier 52 of the ultrahigh pressure fluid system 50 may further comprise a recess 72 formed along a circumference of at least a portion of the outer surface 56 of the seal carrier 52 to promote a distribution of stresses in a less concentrated manner across at least a portion of a cross- sectional area of the seal carrier 52. The seal carrier 52 may further comprise at least one vent to allow water that may potentially seep between the seal carrier 52 and the seal 62, to vent away from this region to a surrounding environment, such as, for example, the bore 13 in which the plunger 12 reciprocates during operation. While known dynamic seal assemblies, such as the dynamic seal assemblies discussed immediately above, provide suitable sealing

arrangements under many operating conditions, Applicants believe it would be desirable in many situations to further optimize the operation of high pressure pumps and ultrahigh pressure pumps and increase the longevity of components thereof, particularly for operation at ultrahigh-high pressures of up to and beyond 87,000 psi, and including pressures above 100,000 psi.

Figures 3 through 5 show one embodiment of a dynamic seal assembly 100 according to one embodiment of the present invention that is particularly well adapted for increasing the longevity of the components thereof and a plunger (not shown) which reciprocates through the dynamic seal assembly 100 during the operation of a host pump (not shown), such as, for example, an intensifier pump of the type partially shown in Figures 1 and 2.

According to the example embodiment of Figure 3, the dynamic seal assembly 100 includes a seal carrier 102 and a bearing 104. The bearing 104 may be press-fit into the seal carrier 102. Accordingly, the seal carrier 102 may include interior features which are correspondingly shaped to exterior features of the bearing 104 to receive the bearing 104 in a manner that slightly compresses the bearing 104 and resists inadvertent withdrawal of the bearing 104 from the seal carrier 102. Further details of the seal carrier 102 and bearing 104 of the dynamic seal assembly 100 can be seen in the cross- sectional views of Figures 4 and 5.

As shown in Figures 4 and 5, the seal carrier 102 includes an external surface 1 10 that is shaped to sealingly mate with a cylinder of a host pump when the seal carrier 102 is installed in a mouth of the cylinder and urged toward the cylinder by a compressive force during installation, such as by tensioning tie rods or other appropriate devices. The seal carrier 102 further includes a seal recess 1 12 to receive an annular seal (not shown) that includes a central aperture through which a plunger of the host pump reciprocates during operation, the annular seal being sized to sealingly engage the plunger. The seal recess 1 12 may be shaped to captively receive the annular seal such that the annular seal is prevented from displacing in either of opposing longitudinal directions.

As further shown in Figures 4 and 5, a supplemental seal recess 1 14 may be formed in the seal recess 1 12 for receiving a supplemental seal, such as an o-ring or other similar seal, which differs in material and properties from that of the annular seal engaging the plunger during operation. In a fully assembled state, the seal carrier 102 receives the supplemental seal in the supplemental seal recess 1 14 and the annular seal in the seal recess 1 12, the annular seal and supplemental seal cooperating to provide a suitable seal around the plunger during operation as supported by the seal carrier 102, and more particularly, an end 1 16 of the seal carrier 102 which is shaped to extend at least partially into the cylinder of the host pump when the seal assembly 100 is installed. The seal carrier 102 may further include one or more vents 1 18 communicating with the seal recesses 1 12, 1 14 to relieve pressure that may otherwise build behind the seals during operation.

With continued reference to Figures 4 and 5, the bearing 104 is received and circumferentially surrounded by the seal carrier 102 at a position adjacent the seal recess 1 12 such that when the annular seal is installed, a terminal end 122 of the bearing 104 abuts the annular seal. The bearing 104 includes a first portionl 24 having an inner surface 126 of a first diameter and a second portion 128 having an inner surface 130 of a second diameter greater than the first diameter. The first diameter being sized such that when the seal carrier 102 receives the annular seal during operation the inner surface 126 of the first portion 124 of the bearing is generally coextensive with the inner surface of the annular seal, which may advantageously prevent the annular seal from extruding into gaps that might otherwise be present between the bearing 104 and an exterior surface of the plunger. The second diameter of the inner surface 130 of the second portion 128 is sized smaller than the first diameter of the inner surface 126 of the first portion 124 yet sized to ensure that at least a portion of the inner surface 130 of the second portion 128 of the bearing 104 contacts the plunger during at least a portion of operation, such as, for example, during periods characterized by high or ultrahigh system pressure. In some embodiments, the first diameter of the inner surface 126 of the first portion 124 of the bearing 104 is at least 0.001 inch less than the second diameter of the inner surface 130 of the second portion 128 of the bearing 104, and in some embodiments, the first diameter of the inner surface 126 of the first portion 124 of the bearing 104 is between about 0.001 inch and about 0.025 inch less than the second diameter of the inner surface 130 of the second portion 128 of the bearing 104. The second diameter of the inner surface 130 of the second portion 128 is also sized relative to the first diameter of the inner surface 126 of the first portion 124 to substantially reduce contact stresses arising from contact of the second portion 128 of the bearing 104 with the plunger during operation, and particularly during periods when system pressure may be relatively low, such as, for example, during an intake stroke of the plunger.

The bearing may include a third or intermediary portion 132 between the first portion 124 and the second portion 128. The third or intermediary portion 132 may have a tapered inner surface 134. When so provided, the tapered inner surface 134 of the third or intermediary portion 132 may gradually transition the first diameter of the inner surface 126 of the first portion 124 to the second diameter of the inner surface 130 of the second portion 128 over a relatively short distance or a relatively long distance. In some embodiments, the draft of the tapered inner surface 134 may be between about ten degrees and about fifty degrees, and in other embodiments, may be between about fifteen degrees and about thirty degrees. Collectively, the inner surfaces 126, 130, 134 of the first, second and third portions 124, 128, 132 of the bearing 104 may form an entirety of an inner surface of the bearing 104. However, in other embodiments, the inner surface of the bearing may include additional surfaces, such as, for example, concave or convex surfaces which may be provided at the intersection of surfaces having linear profiles.

As can be appreciated from Figures 4 and 5, the inner surface

126 of the first portion 124 of the bearing 104 may extend a relatively short distance in a longitudinal direction defined by a central axis A of the seal assembly 100 when compared to an overall height H of the bearing 104. For example, in some embodiments, the inner surface 126 of the first portion 124 of the bearing 104 may extend less than twenty percent of the overall height H of the bearing 104, or in other embodiments, less than ten percent of the overall height H of the bearing 104.

As can be appreciated from Figures 4 and 5, a central portion 136 of the bearing 104 may have a wall thickness which is less than a respective thickness of each of opposing ends of the bearing 104. In some embodiments, a wall thickness of one end of the bearing 104 may be less than about one-third of a wall thickness of the opposing end of the bearing 104 and a wall thickness of the central portion therebetween may be appreciably less than both ends of the bearing 104. In other embodiments, rather than or in addition to sections having a stepped wall thickness, the bearing 104 may also include a tapered section that increases in wall thickness with increasing distance from the seal recess 1 12 in a direction parallel to the central axis A of the bearing 104. The tapered section may increase continuously in wall thickness or may include a step where the first portion 124 of the bearing 104 transitions to the second portion 128 of the bearing 104.

In accordance with the illustrated embodiment of the seal assembly 100 of Figures 3 through 5 and variations thereof, described immediately above, the seal assembly 100 can provide a sealing arrangement which advantageously reduces stresses and associated wear between a plunger of a host pump system and the bearing 104 of the seal assembly 100, thereby leading to prolonged component life. In particular, the seal assembly 100 includes a bearing 104 which includes relief within the interior bore or cavity thereof which reduces the normal contact forces (and thus friction) both in terms of magnitude and also in the percentage of time in which certain portions of the bearing 104 are in contact with the plunger during operation. The provided relief feature is particularly advantageous when the system pressure may be at relatively low pressures, such as, for example, during the retraction stroke of pre-compression stroke of a reciprocating plunger. In fact, the relief feature may ensure that, when the system is operating at lower pressures (either due to a low desired output pressure or due to the fact that the plunger of the system is retracting in order to fill the system), the otherwise high contact stresses ultimately transmitted immediately radially inward from the point of sealing contact between the external surface 1 10 of the seal carrier 102 and the cylinder of the host pump (due, for example, to the required tie rod loading of the system) to the plunger/bearing 104 interface are significantly reduced or even eliminated in some instances. Contact loading between the bearing 104 and the plunger is still evident, but it is biased to occur more predominately at the more critical condition of higher system pressures and at preferred areas of the bearing 104. In this manner, the seal assemblies 100 can advantageously prolong the life of the bearing 104 as well as the plunger with which the bearing 104 interoperates.

Figures 6 and 7 show another embodiment of a dynamic seal assembly 200 that is also particularly well adapted for increasing the longevity of the components thereof and a plunger (not shown) which reciprocates through the dynamic seal assembly 200 during operation of a host pump (not shown), such as, for example, the type of intensifier pump partially shown in Figures 1 and 2.

According to the example embodiment of Figures 6 and 7, the dynamic seal assembly 200 includes a seal carrier 202 and a bearing 204. The bearing 204 may be press-fit into the seal carrier 202. Accordingly, the seal carrier 202 may include interior features which are correspondingly shaped to exterior features of the bearing 204 to receive the bearing 204 in a manner that slightly compresses the bearing 204 and resists inadvertent withdrawal of the bearing 204 from the seal carrier 202.

With continued reference to Figures 6 and 7, the seal carrier 202 includes an external surface 210 that is shaped to sealingly mate with a cylinder of a host pump when the seal carrier 202 is installed in a mouth of the cylinder and urged toward the cylinder by a compressive force during installation. The seal carrier 202 further includes a seal recess 212 to receive an annular seal (not shown) that includes a central aperture through which a plunger of the host pump reciprocates during operation, the annular seal being sized to sealingly engage the plunger. The seal recess 212 may be shaped to captively receive the annular seal such that the annular seal is prevented from displacing in either of opposing longitudinal directions.

As further shown in Figures 6 and 7, a supplemental seal recess 214 may be formed in the seal recess 212 for receiving a supplemental seal, such as an o-ring or other similar seal, which differs in material and properties from that of the annular seal engaging the plunger during operation. For example, the annular seal may be made of plastic materials such as ultrahigh molecular weight polyethylene and the supplemental seal may be made of synthetic rubber materials. In a fully assembled state, the seal carrier 202 receives the supplemental seal in the supplemental seal recess 214 and the annular seal in the seal recess 212, with the annular seal and supplemental seal cooperating to provide a suitable seal around the plunger during operation as supported by the seal carrier 202, and more particularly, as supported by an end 216 of the seal carrier 202 which is shaped to extend at least partially into the cylinder of the host pump when the seal assembly 200 is installed. The seal carrier 202 may further include one or more vents 218 communicating with the seal recesses 212, 1 14 to relieve pressure that may otherwise build behind the seals during operation.

With continued reference to Figures 6 and 7, the bearing 204 is received and circumferentially surrounded by the seal carrier 202 at a position adjacent the seal recess 212 such that when the annular seal is installed, a terminal end 222 of the bearing 204 abuts the annular seal. According to the example embodiment shown in Figures 6 and 7, the bearing 204 includes a central aperture 224 of a constant diameter which defines a central longitudinal axis A. It is appreciated, however, that in other embodiments, the central aperture 224 may include two or more sections each having different diameters, similar to the central aperture of the bearing 104 of the example embodiment of Figures 3 through 5. The bearing 204 further includes a tapered section 226 that increases in wall thickness with increasing distance from the seal recess 212 in a direction parallel to the central axis A. The tapered section 226 comprises a significant portion of the bearing 204. For example, in some embodiments, a longitudinal length of the tapered section 226 is greater than thirty percent of an overall height H of the bearing 204. In other embodiments, the longitudinal length of the tapered section 226 may be between about forty percent and about sixty percent of the overall height H of the bearing 204. According to some embodiments, the tapered section 226 may have a draft angle less than about thirty degrees, and in some other embodiments, may have a draft angle between about five degrees and about twenty-five degrees. In still other embodiments, the tapered section 226 may have a draft angle between about ten degrees and about twenty degrees, and in one particularly advantageous embodiment, the tapered section 226 may have a draft angle of about sixteen degrees. The tapered section 226 may be positioned such that, when the seal carrier 202 sealingly mates with the cylinder during operation, a reference line L normal to a tangential contact angle defined by contact between the seal carrier 202 and the cylinder passes through the tapered section 226 of the bearing 204. The tapered section 226 may begin at or proximate a location which is immediately radially adjacent where the seal carrier 202 is configured to sealingly engage the cylinder.

The bearing 204 further includes a terminal section 228 having a constant wall thickness, the wall thickness of the terminal section 228 being thinner than any other portion of the bearing 204 and positioned to abut the annular seal when the annular seal is received in the seal recess 212. In other embodiments, however, the tapered section 226 may continue to the terminal end 222 of the bearing 204. The bearing 204 may further include an upper section 230 having a constant wall thickness. The tapered section 226 may intersect the upper section 230 to form a shoulder 232, the shoulder 232 of the bearing 204 being configured to mate with a corresponding shoulder 234 of the seal carrier 202. According to some embodiments, including the example embodiment shown in Figures 6 and 7, the tapered section 226 may be interposed between two opposing sections 228, 230 each having a uniform wall thickness. The wall thickness of one end 236 of the bearing 204 may be less than about one-third of the wall thickness of the opposing end 238 of the bearing 204 and the wall thickness of the tapered section 226 may vary between such thicknesses. In some embodiments, the wall thickness of the tapered section 226 may vary linearly between a first thickness equal to that of the terminal section 228 and a second thickness that is at least ten percent less than the thickness of the upper section 230.

In accordance with the example embodiment of the seal assembly 200 of Figures 6 and 7 and variations thereof, described immediately above, the seal assembly 200 may provide a sealing arrangement which advantageously resists appreciable plastic deformation of the bearing 204 component that can otherwise arise in other known bearing geometries, and consequently may significantly extend the life of the provided seal. For instance, the tapered section 226 of the bearing 204 provides a geometry which is more resistant to the influence of axial compression caused by static pressure, friction between the bearing 204 and plunger or a combination of the same. This resistance to axial compression and the plastic deformation which can arise from such compression is believed to be beneficial in preventing excessive stresses at the plunger/bearing interface. Accordingly, the seal assemblies 200 may advantageously prolong the life of the bearing 204 as well as the plunger with which the bearing 204 interoperates by providing a bearing 204 in a friction-resistant, structurally robust form factor which also retains sealing characteristics necessary to seal the host system around the plunger as well as to provide an adequate seal at the interface of the seal carrier 202 and cylinder. For instance, the seal assembly 200 also provides sufficient surrounding structure in the body of seal carrier 202 to withstand the entirety of the required tie rod loading, for example, without succumbing to appreciable plastic yielding. There is also sufficient structure in the body of the seal carrier 202 to provide enough rigidity to ensure sufficient contact stresses buildup between the exterior surface 210 of the seal carrier 202 and the cylinder to guarantee a proper metal-to-metal seal at that location.

In view of the above, a high pressure or ultrahigh pressure fluid system (e.g., intensifier pump) provided with seal assemblies 100, 200 of the various embodiments described herein can enable the system to operate quite reliably at pressures up to and beyond 87,000 psi, and including pressures above 100,000 psi. However, while embodiments of the present invention are particularly beneficial at such higher pressure, it will be understood that aspects of the present invention may also have application at lower pressures up to and beyond 40,000 psi.

Moreover, the various embodiments described above can be combined to provide further embodiments. For example, as discussed above, the bearing 104 of the example embodiment of Figures 3 through 5 may include a tapered section having a generally increasing wall thickness similar to the bearing 204 of the example embodiment of Figures 6 and 7, and the bearing 204 of the example embodiment of Figures 6 and 7 may include a central aperture 224 having two or more sections each of different diameters similar to the bearing 104 of the example embodiment of Figures 3 through 5. These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.