WO2017221064A2

WO2017221064A2 - Dual lip seal with controlled variable deformation

Info

Publication number: WO2017221064A2
Application number: PCT/IB2017/000894
Authority: WO
Inventors: Giorgio RAMORINO; Matteo GUINDANI; Claudio FENAROLI
Original assignee: Novotema Spa
Priority date: 2016-06-20
Filing date: 2017-06-20
Publication date: 2017-12-28
Also published as: WO2017221064A3

Abstract

A sealing element is disclosed. The sealing element may include a piston aperture extending through a portion of the sealing element and a sealing surface may be circumferentially formed around the piston aperture. A primary seal and a secondary seal may each project radially outward from the sealing surface and the secondary seal may be axially spaced away from the primary seal along the sealing surface. A piston may extend through the piston aperture and the primary seal may be sealingly engaged with the piston to form a first seal between the sealing element and the piston. The secondary seal may be spaced radially away from the piston such that a gap is defined between the secondary seal and the piston.

Description

DUAL LIP SEAL WITH CONTROLLED VARIABLE DEFORMATION CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is an International Patent Application claiming priority under U.S. 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 62/352,359, filed on June 20, 2016.

TECHNICAL FIELD

[0002] This disclosure relates generally to lip seals and, for example, to lip seals for pistons and cylinders where the pressure inside the cylinder varies during operation.

BACKGROUND

[0003] Damping assemblies often include sliding and/or moving components which incorporate one or more sealing elements configured to provide a variety of sealing needs during operation. For example, the sealing element may provide a fluid tight seal that contains or otherwise seals certain materials (i.e., fluid, oil, lubricant and the like) within a defined area of the sealing assembly. Additionally or alternatively, the sealing element may be configured to provide the fluid tight seal in order to keep contaminants (i.e., dirt, particles, debris) out of the defined area. However, one of the many challenges in maintaining these assemblies in top operational condition is that the sliding and other such movement of the assembly components may cause wear on the sealing elements. As a result, increased wear may result in a decrease of the sealing performance of the sealing element and the overall lifespan of the sealing assembly.

[0004] As such, damping assemblies may incorporate one or more sealing elements that include a plurality of lip seals configured to contact a sealing surface of the assembly in order to create a fluid tight seal. The plurality of lip seals may be compressed or otherwise deformed against the sealing surface to produce an adequate seal that ensures the host of sliding and/or moving parts are properly lubricated and protected from contamination.

Furthermore, the sealing assembly may be configured to produce sufficient sealing pressure during static and/or dynamic operational conditions. As a result, the sealing element may include lip seals that are capable of responding to an increasing/decreasing pressure created within the assembly during operation. Accordingly, the sealing assembly may adjust the sealing element in order to maintain an adequate sealing pressure across the different assembly operational conditions.

[0005] Typical seals with one or more lip seals utilize a constant deformation value on the sealing surface of the lip seals to form the fluid tight seal. However, this constant deformation of the seal causes continuous wear to both lips. Thus, there is a need to improve resistance to wear of dynamic seals such as seals with one or more lip seals because the sealing performance typically gets worse if wear increases.

SUMMARY OF THE DISCLOSURE

[0006] In accordance with one embodiment of the present disclosure, a sealing element is disclosed. The sealing element may include a piston aperture extending through a portion of the sealing element. Furthermore, the sealing element may include a sealing surface circumferentially formed around the piston aperture. A primary seal may project radially outward from the sealing surface defining a primary seal diameter. Additionally, a secondary seal may project radially outward from the sealing surface defining a secondary seal diameter, the secondary seal diameter is greater than the primary seal diameter, and the secondary seal may be spaced axially away from the primary seal along the sealing surface. Moreover, a piston may extend through the piston aperture, wherein the primary seal may be sealingly engaged with the piston to form a first seal between the sealing element and the piston and the secondary seal may be spaced radially away from the piston such that a gap is defined between the secondary seal and the piston when the pressure acting on the sealing element is less than the secondary seal contact pressure.

[0007] In accordance with another embodiment of the present disclosure, a sealing assembly having controlled variable deformation is disclosed. The sealing assembly may include an assembly housing and a sealing element disposed within the assembly housing and the sealing element may have an outer diameter configured to sealingly engage with an inner diameter of the assembly housing. The sealing element may further include a piston aperture extending through a portion of the sealing element. Moreover, the sealing element may include a sealing surface circumferentially formed around the piston aperture. A primary seal may project radially outward from the sealing surface defining a primary seal diameter. A secondary seal may project radially outward from the sealing surface defining a secondary seal diameter, the secondary seal diameter is greater than the primary seal diameter, and the secondary seal may be spaced axially away from the primary seal along the sealing surface. Furthermore, the sealing assembly may include a piston extending through the piston aperture and the piston may be configured to move within the assembly housing. The primary seal may be sealingly engaged with the piston to form a first seal between the sealing element and the piston, and wherein the internal seal is spaced radially away from the piston such that a gap is defined between the internal seal and the piston.

[0008] In accordance with yet another embodiment of the present disclosure, a method of controlling a variable deformation of a sealing assembly is disclosed. The method may included forming a sealing element having a piston aperture extending there through.

Additionally, the method may include defining a sealing surface around a circumference of the piston aperture and the sealing surface may include a primary seal having a primary seal diameter and a secondary seal having a secondary seal diameter. The method may further include inserting a piston through the piston aperture such that a first pressure exerts a first contact pressure on the sealing element causing the primary seal being sealingly engaged with a surface of the piston to form a first seal, and the secondary seal may be spaced radially away from the surface of the piston such that a gap is defined between the secondary seal and the piston.

[0009] Other advantages and features will be apparent from the following detailed description when read in conjunction with the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] For a more complete understanding of the disclosed methods and apparatuses, reference should be made to the embodiment illustrated in greater detail on the accompanying drawings, wherein:

[0011] FIG. 1 is a sectional view of the disclosed seal assembly under a low-pressure condition where the secondary seal is not in contact with the piston;

[0012] FIG. 2 is an enlarged partial view of the seal assembly shown in FIG. 1.

[0013] FIG. 3 is a sectional view of the disclosed seal assembly under a high-pressure condition where the secondary seal is in contact with the piston;

[0014] FIG. 4 is an enlarged partial view of the seal assembly shown in FIG. 3;

[0015] FIG. 5 is a graphical illustration of the primary seal and secondary seal contact area during the low pressure condition of FIG. 1 and the high-pressure condition of FIG. 3;

[0016] FIG. 6 is a graphical illustration of a standard lip contact area during the low pressure condition and the high pressure condition; [0017] FIG. 7 is a graphical illustration of the friction force behavior observed between the seal assembly of FIGS. 1-4 and a seal assembly with a standard sealing element; and

[0018] FIG. 8 is a flowchart depicting a method of controlling a variable deformation of the sealing assembly of FIGS. 1-4.

[0019] The drawings are not necessarily to scale and may illustrate the disclosed embodiments diagrammatically and/or in partial views. In certain instances, the drawings may omit details which are not necessary for an understanding of the disclosed methods and apparatuses or which render other details difficult to perceive. It should be understood, of course, that this disclosure is not limited to the particular embodiments illustrated herein.

DETAILED DESCRIPTION

[0020] Various aspects of the disclosure will now be described with reference to the drawings, wherein like reference numbers refer to like elements, unless specified otherwise. Referring now to the drawings and with specific reference to FIGS. 1-4, an assembly 20 incorporating a sealing element 22 is illustrated. Furthermore, in an embodiment, the assembly 20 including the sealing element 22 may be configured as a sealing assembly; however other assemblies are possible. The assembly 20 may be configured to provide damping, actuation, rotation, or other such condition. Moreover, the assembly further includes a piston 24 and an assembly housing 26, and the sealing element 22 may be disposed within the housing. The sealing element 22 may be configured to be circular in shape such that the sealing element 22 has a sealing element outer surface 27 with an outer diameter 28 which corresponds to a housing inner diameter 30. The sealing element 22 may be fabricated from an elasomer material such as but not limited to, nitrile butadine rubber (NBR).

However, other materials that exhibit the desired properties (i.e., hardness/softness, wear resistance, chemical resistance, and the like) may be used to fabricate the sealing element 22. [0021] As such, the sealing element 22 may be positioned within the assembly housing 26 so the outer surface 27 of the sealing element 22 sealingly engages with the inner surface 32 of the assembly housing 26 to produce a substantially fluid tight (i.e., air or liquid) seal. Moreover, the sealing element 22 may have a variable inner diameter 34 defined by a piston aperture 36 that extends through the sealing element 22. The inner diameter 34 of the sealing element 22 corresponds to an outer diameter 38 of the piston 24 such that the sealing element 22 sealingly engages with an outer surface 40 of the piston 24. In one non-limiting example, the sealing element 22 may be configured as a dual-lip seal, and the the sealing element 22 may be specifically suitable for producing a fluid tight (i.e., air or liquid) seal when the assembly 20 is operated or otherwise activated between a static state and a dynamic state.

[0022] Referrning to FIGS. 2 and 4, with continued reference to FIGS. 1 and 3, the sealing element 22 may be configured as a dual-lip seal having a sealing surface 41 formed around a circumference of the piston aperture 36. The sealing surface 41 may be configured with a primary seal 42 or external lip and a secondary seal 44 or internal lip; however other configurations and number of lips on the sealing element 22 are possible. In one non-limiting example, the sealing element 22 may be configured such that the primary seal 42 and the secondary seal 44 are adjacently positioned to the outer surface 40 of the piston 24. As such, the variable inner diameter 34 of the sealing element may be further configured with a primary seal diameter 43 at the primary seal 42 and a secondary seal diameter 45 at the secondary seal 44. In some embodiments, the primary seal diameter 43 may be slightly smaller than the outer diameter 38 of the piston 24 and the secondary seal diameter 45 may be slighly larger than the outer diameter 38 of the piston 24. As a result, during a static operational condition, the primary seal 42 may be in direct contact with the outer surface 38 of the piston 24 and the secondary seal 44 may not be in direct contact with the outer surface 38 of the piston 24. [0023] Furthermore, the primary seal 42 may be configured to be under constant deformation when the assembly 20 is in both a static operational state and a dynamic operational state. The constant deformation of the primary seal 42 produces sufficient sealing pressure between the primary seal 42 and the outer surface 40 of the piston 24. In an embodiment, the constant deformation may be caused by a first contact pressure that is equal to or greater than a first pressure PI present inside the assembly 20 during the static operational state (i.e., no movements among parts). As a result, the sealing element 22 may form a first seal 46 between primary seal 42 and the outer surface 40 of the piston 24 because the first contact pressure (i.e., PI) produces sufficient sealing pressure to engage or otherwise seal the primary seal 42 with the outer surface 40 of the piston 24.

[0024] However, the first contact pressure PI may not be sufficient to sealingly engage the secondary seal 44 with the outer surface 40 of the piston 24. In some embodiments, when the first contact pressure acts upon the sealing element 22, the deformation of the secondary seal 44 may be equal to zero or very close to zero. As a result, the secondary seal 44 is adjacently positioned relative to, but not in direct contact with, the outer surface 40 of the piston 24. When the first contact pressure PI acts upon the sealing element 22, and deformation of the secondary seal 44 is equal to zero or very close to zero, there may be a gap 48 present between the secondary seal 44 and the outer surface 40 of the piston 24. As a result, when the assembly 20 is in a standby or static operational condition, the first contact pressure present within the assembly housing 26 may be sufficient to sealingly engage the primary seal 42 with the outer surface 40 of the piston 24 while the secondary seal 44 is disengaged (i.e., no deformation) from the outer surface 40 of the piston 24.

[0025] Furthermore, as illustrated in FIGS. 3 and 4, the sealing element 22 may be configured such that both of the primary seal 42 and the secondary seal 44 are under deformation during activation or a dynamic operational condition (i.e., movement of components) of the assembly 20 where the pressure in the assembly 20 is greater than the first contact pressure PI. In some embodiments, movement by the piston 24 or other such component of the assembly 20, may cause the primary seal 42 and secondary seal 44 to each be sealingly engaged with the outer surface 40 of the piston 24 and form a fluid tight seal within the assembly 20. In one non-limiitng example, sliding or other such movement of the piston 24 may change the internal volume of the assembly 20 which may generate an increase in pressure within the assembly housing 26. This increase in pressure may, in turn, produce a second contact pressure that acts upon the sealing element 22. In some embodiments, the second contact pressure may be dependent upon the sum of the first pressure PI and second pressure P2 generated during activation or operation of the assembly 20.

[0026] Generally, the internal pressure of the assembly 20 increases with an initial movement or an increase in movement of the piston 24 relative to the sealing element 22. As such, the movement of the piston 24 may cause a change in the internal volume of the assembly 20 which may correspondinly cause an increase in the second pressure P2 within the assembly housing 26. Conversely, the internal pressure of the assembly 20 may correspondingly decrease with a reduction in movement of the piston 24 relative to the sealing element 22. As described above, the second contact pressure may be defined by the sum of the first pressure PI and the second pressure P2, and during operation of the assembly 20 the first pressure PI and the second pressure P2 may generate the second contact pressure to act upon the sealing element 22 in order to sealingly engage both the primary seal 42 and the secondary seal 44 with the outer surface 40 of the piston 24.

[0027] As illustrated in FIGS. 1 and 3, the first pressure PI and the second pressure P2, may be directed into an annular cavity 49 disposed between the piston aperture 36 and the outer diameter 28 of the sealing element 22. Accordingly, during the static operational condition the first contact pressure associated with the first pressure PI may interact with the annular cavity 49 such that the primary lip 42 is placed in direct contact with the outer surface 40 of the piston 24. Furthermore, during the dynamic operational condition the second contact pressure associated with the first pressure PI and the second pressure P2 may interact with the annular cavity 49 such that both the primary lip 42 and the secondary lip 44 are placed in direct contact with the outer surface 40 of the piston 24.

[0028] As further illustrated in FIG. 4, when the second contact pressure is applied to the annular cavity 49 and other portions of the sealing element 22, the deformation of the secondary seal 44 may no longer be equal to zero and the secondary seal 44 may be sealingly engaged with the outer surface 40 of the piston 24. As a result, the secondary seal 44 may form a second seal 50 between the sealing element 22 and the outer surface 40 of the piston 24. Therefore, during operation of the assembly 20, the first pressure PI and the second pressure P2 may create the second contact pressure to act on the sealing element 22 such that the primary seal 42 forms the first seal 46 and the secondary seal 44 forms the second seal 50 between the sealing element 22 and the outer surface 40 of the piston 24. Additionally, as the assembly 20 internal pressure increases during the dynamic operational condition, the deformation of the secondary seal 44 may similarly increase to correspondingly enlarge or otherwise increase a contact surface area of the second seal 50 formed between the secondary seal 44 and the outer surface 40 of the piston 24. Conversely, as the second contact pressure decreases, the deformation of the secondary seal 44 may similarly decrease to reduce the contact surface area of the second seal 50 formed between the secondary seal 44 and the outer surface 40 of the piston 24. When the second contact pressure decreases to zero, or close to zero, the secondary seal 44 may no longer be in direct contact with the outer surface 40 of the piston 24 and the gap 48 may reform between the secondary seal 44 and the outer surface 40 of the piston 24. [0029] Referring to FIG. 5, with continued reference to FIGS. 1-4, a dual-lip sealing element performance graph 52 of the deformed surface area of the primary seal 42 and secondary seal 44 is shown. In the dual-lip sealing element performace graph 52, the x-axis 54 labeled z-coordinate (mm) represents the surface area of each deformed portion of the primary seal 42 and the secondary seal 44 along an axial position of the pistion. The y-axis 56 labeled contact pressure, contact pair (bar) represents the contact pressure exerted by the sealing element 22. Furthermore, the primary seal 42 performance is represented by primary seal data 58 and the secondary seal 44 performance is illustrated by secondary seal data 60.

[0030] As discussed above, the primary seal 42 may generally be in contact with the outer surface 40 of the piston 24 due to the first contact pressure being greater than the first pressure PI present within the assembly housing 26. In one non-limiting example, the first contact pressure (i.e., PI) corresponds to a contact pressure of slightly less than 15 bar acting on the primary lip 42 and the second contact pressure (i.e., PI + P2) corresponds to a contact pressure of approximately 18 bar acting on the primary lip 42. As such, the primary seal data 58 illustrates that the increase in the contact pressure between the first contact pressure and the second contact pressure generally produces only a small increase in the deformation surface area of the first seal 46 formed between the primary seal 42 and the outer surface 40 of the piston 24.

[0031] Conversely, the secondary seal 44 may generally not be in contact with the outer surface 40 of the piston 24 when the assembly 20 is in an inactive or static operational condition. In one non-limiting example, the first contact pressure (i.e., PI) corresponds to a contact pressure of slightly greater than 2 bar acting on the secondary lip 44 and the second contact pressure (i.e., PI + P2) of approximately 13 bar acting on the secondary lip 44. When the assembly 20 is activated, the internal pressure within the assembly housing 26 increases producing a second contact pressure. The second contact pressure acts on the sealing element 22 causing the secondary seal 44 to contact the outer surface 40 of the piston 24. As the secondary seal 44 maintians contact with the piston 24, there is an increase in the deformation surface area of the second seal 50 formed between the secondary seal 44 and the outer surface 40 of the piston 24.

[0032] As shown by secondary seal data 60, the deformation surface area of the secondary seal 44, and the second seal 50, may continue to increase as the contact pressure within the assembly houisng increases between the first and second contact pressures. However, the increase in pressure within the assembly housing 26 presented at the second contact pressure does not cause a corresponding increase in the deformation surface area of the first seal 46 formed between the primary seal 42 and the outer surface 40 of the piston 24. Such performance by the sealing element 22 may produce a lower intial static force during the activation of the assembly 20. Furthermore, the sealing element 22 may show reduced wear during cyclic activity between the static and dynamic operational conditions, and as a result, the sealing element 22 may show an improved or extended lifetime.

[0033] For comparison, FIG. 6 illustrates a standard lip (i.e., non dual-lip) sealing element performance graph 62. Similar to the dual-lip sealing element performace graph 52, the x- axis 64 of the standard lip sealing element performance graph 62 represents the surface area of each deformed portion of a standard lip of a standard lip seal, and the y-axis 66 represents the contact pressure exerted on the standard lip seal. Reviewing the standard lip sealing element performance graph 62 it is observed that when the internal pressure of the assembly incorporating the standard lip seal increases there is a small change or low jump of the contact pressure acting on the standard lip sealing element. This characteristic of the standard lip seal is highlighted by the close grouping of contact pressure points 68 shown on the standard lip sealing element performance graph 62. Additionally, the standard lip sealing element performance graph 62 shows that as the internal pressure of the assembly incorporating the standard lip seal increases the contact surface area of the standard lip seal continues to increase.

[0034] Such an increase in the contact surface area as observed with the standard lip seal is different from the primary seal 42 performance of the sealing element 22. For example, referring back to FIG. 5, the primary seal data 58 shows a larger change or higher jump of the contact pressure acting on the primary seal 42 of the sealing element 22 when the internal pressure of the assembly 20 increases. This characteristic of the primary seal 42 is shown by the primary seal data 58 having a more spread out grouping of contact pressure points 70 for the primary seal 42 of the sealing element 22. Additionally, the primary seal data 58 shows that the deformation surface area of the primary seal 42 remains relatively constant as the internal pressure of the assembly 20 increases. This differs from the behavior observed with the standard lip seal because the contact surface area of the standard lip seal continues to increase as the internal pressure increases within the assembly incorporating the standard lip seal.

[0035] FIG. 7 illustrates another comparison between sealing element 22 (i.e., dual-lip seal) and two standard lip seals in the friction force comparison histogram 72. The evaluation of the seals compared static friction values and sliding friction values of each seal over a period of time, and the evaluation included standard seal 1 data 74, standard seal 2 data 76, and dual-lip seal data 78. In a first test, the friction values (i.e., static and sliding) for each seal in new or unused condition were evaluated at intervals of 1 week, 5 weeks, and 15 weeks, as illustrated in the histogram legend 80. After 1 week, the static friction values were measured and found to be comparable between the standard seal 1 data 74, standard seal 2 data 76, and the dual lip seal data. However, at the later measurement intervals of 5 weeks and 15 weeks there was a noticable difference between the static friction values of standard seal 1 data 74 and standard seal data 76, and the dual-lip seal data 78. At the 5 week interval and 15 week interval both the standard seal 1 data 74 and standard seal data 76 shows an increase in the static friction force. Whereas, at the 5 week interval and 15 week interval the dual-lip seal data 78 shows the static friction force remained relatively constant. Such an observable difference between the standard lip seals and the dual-lip seal of sealing element 22 may be attributed to the lower deformation surface area of the primary seal 42 during the static operational condition.

[0036] Additionally, the evaluation of the seals compared static friction values and sliding friction values of each seal after a predetermined amount of use. In this case, each of the standard seals and the dual lip seal were put through 100,000 use cycles and the static and sliding friction force was evaluated after wating 1 week. As shown in the the friction force comparison histogram 72, both the standard seal 1 data 74 and the standard seal 2 data 76 show an increase in static friction force after 100,000 cycles compared to the 1 week data measured after 0 cycles. However, the dual lip seal data 78 showed that even after 100,000 cycles the static friction force remained constant when compared with the 1 week data measured after 0 cycles. Additionally, the dual lip seal data 78 shows that the static friction force after 100,000 cycles was lower than both of the standard seal 1 and standard seal 2 data 74, 76.

Industrial Applicability

[0037] Referring now to FIG. 8, and with continued reference to the proceeding FIGS. 1-7, a flowchart illustrating an exemplary method of controlling a variable sealing assembly 82 is illustrated. In a first block 84, the sealing element 22 is formed and in some embodiments, the sealing element is configured to be disposed within the assembly housing 26 of the assembly 20 to produce a fluid tight seal within the assembly housing 26. In one non- limiting example, the assembly housing 26 may be cylindrical in shape such that the assembly 20 takes on the cylindrical shape. The sealing element 22 may further be configured with a sealing element 22 outer diameter 28 that is substantially similar in size to housing inner diameter 30 of the assembly housing 26. As a result, when the sealing element 22 is disposed within the assembly housing 26 the outer diameter 28 of the sealing element 22 may sealingly engage with an inner surface 32 of the assembly housing 26 to form a fluid tight seal between the sealing element 22 and the assembly housing 26. Additionally, the sealing element 22 may include a piston aperture 36 configured to extend through the sealing element 22. The piston aperture 36 may be circular in shape, or any other such shape that is complimentary to the piston 24 of the assembly 20. As such, the sealing element 22 includes an inner diameter 34 that determines the size of the piston aperture 36 formed in the sealing element 22.

[0038] In a next block 86, a sealing surface 41 may be defined around the circumference of the piston aperture 36. In one embodiment, the sealing surface 41 may be configured with a primary seal 42 and a secondary seal 44 that both project radially outward from the sealing surface 41. Moreover, the primary seal 42 and the secondary seal 44 may be axially spaced from each other along the sealing surface such that there is a separation of the primary seal 42 and the secondary seal 44. The piston 24 may be inserted through the piston aperture 36 in a next block 88, and the primary seal 42 and secondary seal 44 may be adjacently positioned to the outer surface 40 of the piston 24. The sealing surface 41, and more specifically the primary seal 42 and the secondary seal 44 may be configured to variably engage or otherwise interact with the outer surface 40 of the piston 24. In some embodiments, the primary seal 42 and the secondary seal 44 may be compressed against the piston 24 to form one or more fluid tight seals between the sealing element 22 and the piston 24.

[0039] In a next block 90, the pressure within the assembly housing 26 may be controlled such that there is a first contact pressure exerted upon the sealing element 22. Furthermore, the sealing element 22 may be configured to provide variable sealing capabilities during different assembly 20 operating conditions. For example, the sealing element 22 may adjust its sealing capabilities between static or inactive operational conditions and dynamic or active operational conditions. During static operating conditions, the assembly housing 26 may have a first pressure PI and the first contact pressure may be configured to be greater than the first pressure PI. Furthermore, the sealing element 22 may respond to the first contact pressure such that the primary seal 42 is engaged or otherwise deformed against the outer surface 40 of the piston 24 to form a first seal 46. The sealing element 22 may additionally respond to the first contact pressure such that there is a gap 48 between the secondary seal 44 and the outer surface 40 of the piston 24. Therefore, the first contact pressure does not cause the secondary seal 44 to be sealingly engaged with the piston 24. As a result, during periods of static operating conditions the primary seal 42 may remain in constant contact and engagement with the outer surface 40 of the piston 24 and the secondary seal 44 may be disengaged with the outer surface 40 of the piston.

[0040] During a dynamic operating condition, the piston 24 and other components of the assembly may be moved. Such movement may cause the pressure to increase within the assembly housing 26 to a second pressure P2. In some embodiments, the second pressure P2 generates a second contact pressure that acts upon the sealing element 22 and the second contact pressure causes the secondary seal 44 to sealingly engage with the outer surface 40 of the piston 24 to form a second seal 50 between the sealing element 22 and the piston 24. Furthermore, the second contact pressure maintains the engagement of the primary seal 42 with the piston 24. As a result, during dynamic operating conditions both the primary seal 42 and the secondary seal 44 may be sealingly engaged with the outer surface 40 of the piston 24 such that both the first seal 46 and second seal 50 is formed between the sealing element 22 and the piston 24. [0041] The performance of the sealing element 22 may provide a lower initial static force or breakaway force requirement to activate the assembly 20 due to the reduced surface area of the sealing element 22 in contact with the piston 24 during static operational conditions. The reduction in sealing element 22 surface area in contact with the piston 24 may be attrubuted to that only a portion of the primary seal 42 is engaged with the piston 24 when the assembly 20 is in a static position. Additionally, the sealing element 22 may show reduced wear during operation of the assembly 20 because the engaged or deformed surface area of the first seal 46 formed by the primary seal 42 is held relatively constant during the dynamic operational condition. In other words, as the pressure within the assembly housing 26 increases during the dynamic operational condition the increased contact pressure exerted on the sealing element 22 does not further compress the primary seal 42. As a result, surface area of the first seal 46 remains relatively unchanged when the assembly cycles between static and dynamic operating conditions, the and the deformation surface area of the second seal 50 only increases as the pressure increases during the dynamic operational condition.

[0042] While the foregoing detailed description has been given and provided with respect to certain specific embodiments, it is to be understood that the scope of the disclosure should not be limited to such embodiments, but that the same are provided simply for enablement and best mode purposes. The breadth and spirit of the present disclosure is broader than the embodiments specifically disclosed and encompassed within the claims appended hereto. Moreover, while some features are described in conjunction with certain specific

embodiments, these features are not limited to use with only the embodiment with which they are described, but instead may be used together with or separate from, other features disclosed in conjunction with alternate embodiments.

Claims

CLAIMS What is claimed is:

1. A sealing element comprising:

a piston aperture extending through a portion of the sealing element;

a sealing surface circumferentially formed around the piston aperture;

a primary seal projecting radially outward from the sealing surface defining a primary seal diameter;

a secondary seal projecting radially outward from the sealing surface defining a secondary seal diameter, the secondary seal diameter is greater than the primary seal diameter, and the secondary seal is spaced axially away from the primary seal along the sealing surface, the secondary seal has a secondary seal diameter greater than a primary seal diameter; and

a piston extending through the piston aperture, wherein the primary seal is sealingly engaged with the piston to form a first seal between the sealing element and the piston and the secondary seal is spaced radially away from the piston such that a gap is defined between the secondary seal and the piston.

2. The sealing element of claim 1, wherein a first pressure exerted on the sealing element generates a first contact pressure that causes the primary seal to sealingly engage the piston and the first contact pressure causes the secondary seal to maintain the gap between the secondary seal and the piston.

3. The sealing element of claim 2, wherein the first contact pressure is associated with a static operational condition of the sealing element.

4. The sealing element of claim 2, wherein the first contact pressure generates a static friction force on the sealing element and the static friction force remains constant over an operational lifetime of the sealing element.

5. The sealing element of claim 1, wherein a second pressure exerted on the sealing element generates a second contact pressure that causes both the primary seal and the secondary seal to sealingly engage the piston and the second contact pressure causes the secondary seal to form a second seal between the sealing element and the piston.

6. The sealing element of claim 5, wherein the second contact pressure is associated with a dynamic operational condition of the sealing element.

7. The sealing element of claim 6, wherein the second contact pressure produces an increased pressure compared to a first contact pressure exerted on the sealing element during a static operational condition, and wherein the increased pressure produced by the second contact pressure is exerted on the sealing element to produce a minimal increase in a first seal surface area of the primary seal.

8. The sealing element of claim 6, wherein the second contact pressure produces an increased pressure compared to a first contact pressure exerted on the sealing element during a static operational condition, and wherein the increased pressure produced by the second contact pressure is exerted on the sealing element to produce an increase in a second seal surface area of the secondary seal.

9. A sealing assembly having controlled variable deformation, the sealing assembly comprising:

an assembly housing;

a sealing element disposed within the assembly housing, the sealing element having an outer diameter configured to sealingly engage with an inner diameter of the assembly housing, the sealing element comprising:

a piston aperture extending through a portion of the sealing element, a sealing surface circumferentially formed around the piston aperture, a primary seal projecting radially outward from the sealing surface defining a primary seal diameter, a secondary seal projecting radially outward from the sealing surface defining a secondary seal diameter, the secondary seal diameter is greater than the primary seal diameter, and the secondary seal being spaced axially away from the primary seal along the sealing surface, and

a piston extending through the piston aperture and the piston configured to move within the assembly housing, wherein the primary seal is sealingly engaged with the piston to form a first seal between the sealing element and the piston, and wherein the secondary seal is spaced radially away from the piston such that a gap is defined between the secondary seal and the piston.

10. The sealing assembly of claim 9, wherein a first pressure within the assembly housing generates a first contact pressure that is exerted on the sealing element causing the primary seal to sealingly engage the piston and the first contact pressure causes the secondary seal to maintain the gap between the secondary seal and the piston.

11. The sealing assembly of claim 10, wherein the first contact pressure is generated during a static operational condition of the sealing assembly.

12. The sealing assembly of claim 10, wherein the first contact pressure generates a static friction force on the sealing element and the static friction force remains constant over an operational lifetime of the sealing assembly.

13. The sealing assembly of claim 9, wherein a second pressure within the assembly housing generates a second contact pressure that causes both the primary seal and the secondary seal to sealingly engage the piston, and the second contact pressure causes the secondary seal to form a second seal between the sealing element and the piston.

14. The sealing assembly of claim 13, wherein the second contact pressure is generated during a dynamic operational condition of the sealing assembly.

15. The sealing assembly of claim 14, wherein the second contact pressure produces an increased pressure within the assembly housing compared to a first contact pressure exerted on the sealing element during a static operational condition of the sealing assembly, and wherein the increased pressure produced by the second contact pressure is exerted on the sealing element to produce a minimal increase in a first seal surface area of the primary seal.

16. The sealing assembly of claim 14, wherein the second contact pressure produces an increased pressure within the assembly housing compared to a first contact pressure exerted on the sealing element during a static operational condition of the sealing assembly, and wherein the increased pressure produced by the second contact pressure is exerted on the sealing element to produce an increase in a second seal surface area of the secondary seal.

17. A method of controlling a variable deformation of a sealing assembly, the method comprising:

forming a sealing element having a piston aperture extending there through;

defining a sealing surface around a circumference of the piston aperture, the sealing surface including a primary seal having a primary seal diameter and a secondary seal having a secondary seal diameter;

inserting a piston through the piston aperture such that the primary seal and the secondary seal are adjacently positioned to a surface of the piston; and

controlling a pressure within the sealing assembly such that a first pressure exerts a first contact pressure on the sealing element causing the primary seal being sealingly engaged with the surface of the piston to form a first seal, and the secondary seal being spaced radially away from the surface of the piston such that a gap is defined between the secondary seal and the piston.

18. The method of claim 17, wherein controlling the pressure within the sealing assembly further includes generating a second pressure exerting a second contact pressure on the sealing element causing the primary seal to remain sealingly engaged with the surface of the piston and maintain the first seal, and wherein the second contact pressure causing the secondary seal being sealingly engaged with the surface of the piston to form a second seal.

19. The method of claim 18, wherein the first contact pressure is generated within the assembly during a static operating condition and the second contact pressure is generated within the assembly during a dynamic operating condition.

20. The method of claim 18, wherein the second contact pressure produces an increased pressure within the assembly, and wherein the increased pressure exerted on the sealing element causes a minimal increase in a first seal surface area of the primary seal and causes an increase in a second seal surface area of the secondary seal.