Damper with hydraulic end stop

A damper includes a pressure tube and a piston. The piston defines a rebound chamber and a compression chamber. The damper further includes a piston rod that reciprocates with the piston. The damper includes a sealing ring slidably disposed around the piston rod. The sealing ring includes a locking mechanism adapted to lock the sealing ring around the piston rod. The sealing ring also includes an inner surface having a plurality of concave surfaces and a plurality of convex surfaces. Each of the plurality of concave surfaces is located adjacent to a corresponding convex surface of the plurality of convex surfaces. The sealing ring further includes an upper surface extending between the outer and inner surfaces. The upper surface defines a plurality of channels. The sealing ring further includes grooves and bleeds for tuning energy dissipated by the damper during rebound stroke to help reduction of noise.

TECHNICAL FIELD

The present disclosure generally relates to dampers. More particularly, the present disclosure relates to a damper having a hydraulic end stop.

BACKGROUND

Shock absorbers/dampers are generally installed on different types of equipment, such as vehicles, to damp vibrations during operation. For example, dampers are generally connected between a body and the suspension system of the vehicle in order to absorb the vibrations. Conventional dampers typically include a pressure tube, a reserve tube, a piston, a piston rod, and one or more valves. During a compression stroke and a rebound stroke of the damper, the piston may limit a flow of damping fluid between working chambers defined within a body of the damper due to which the damper produces a damping force for counteracting the vibrations. By further restricting the flow of damping fluid within the working chambers of the damper, greater damping forces may be generated by the damper.

For reasons relating to comfort, the damping force of the damper cannot be increased beyond a certain threshold as it may cause an axle of the vehicle and the damper to move into a rebound limit at high speeds. A hydraulic rebound end stop is typically provided to reduce the speed at which the damper moves into the rebound limit. Current hydraulic rebound end stop designs utilize a sealing ring, such as a brass sealing ring, with a controlled gap. When such sealing rings enter a hydraulic rebound stop zone towards an end of the rebound stroke, a high damping force is created that causes dissipation of kinetic energy and helps in reduction of noise. Under certain conditions, for example, when the sealing ring is outside the hydraulic rebound stop zone or in a transition zone, high velocity of oil flowing around the sealing ring forces the sealing ring to plastically deform and open up. Such unlocking of the sealing ring may cause the sealing ring to fail and may in turn affect hydraulic rebound end stop function of the damper and binding in the damper.

SUMMARY

In an aspect of the present disclosure, a damper is provided. The damper includes a pressure tube defining a first end and a second end opposite to the first end. The damper also includes a piston slidably disposed within the pressure tube. The piston defines a rebound chamber and a compression chamber within the pressure tube. The damper further includes a piston rod adapted to reciprocate with the piston. The piston rod is partially received within the pressure tube. The damper includes a sealing ring slidably disposed around the piston rod. The sealing ring includes an inner surface facing the piston rod. The inner surface includes a plurality of concave surfaces and a plurality of convex surfaces. Each of the plurality of concave surfaces is located adjacent to a corresponding convex surface of the plurality of convex surfaces. The sealing ring also includes an upper surface extending between the outer and inner surfaces. The upper surface defines a plurality of channels.

In another aspect of the present disclosure, a damper is provided. The damper includes a pressure tube defining a first end and a second end opposite to the first end. The damper also includes a piston slidably disposed within the pressure tube. The piston defines a rebound chamber and a compression chamber within the pressure tube. The damper further includes a piston rod adapted to reciprocate with the piston. The piston rod is partially received within the pressure tube. The damper includes a first collar disposed around the piston rod. The damper also includes a second collar disposed around the piston rod and axially spaced apart from the first collar. The damper further includes a sealing ring slidably disposed around the piston rod and disposed between the first and second collars. The sealing ring includes an inner surface facing the piston rod. The inner surface includes a plurality of concave surfaces and a plurality of convex surfaces. Each of the plurality of concave surfaces is located adjacent to a corresponding convex surface of the plurality of convex surfaces. The sealing ring also includes an outer surface opposite to the inner surface. The outer surface defines at least one groove. The sealing ring further includes an upper surface extending between the outer and inner surfaces. The upper surface defines a plurality of channels.

In yet another aspect of the present disclosure, a damper is provided. The damper includes a pressure tube defining a first end and a second end opposite to the first end. The damper also includes a piston slidably disposed within the pressure tube. The piston defines a rebound chamber and a compression chamber within the pressure tube. The damper further includes a piston rod adapted to reciprocate with the piston. The piston rod is partially received within the pressure tube. The damper includes a first collar disposed around the piston rod. The damper also includes a second collar disposed around the piston rod and axially spaced apart from the first collar. The damper further includes a snap ring disposed adjacent to the second collar and extending along a circumference of the piston rod. The snap ring is at least partially received within a ring groove of the piston rod. The damper includes a sealing ring slidably disposed around the piston rod and disposed between the first and second collars. The sealing ring includes an inner surface facing the piston rod. The inner surface includes a plurality of concave surfaces and a plurality of convex surfaces. Each of the plurality of concave surfaces is located adjacent to a corresponding convex surface of the plurality of convex surfaces. The sealing ring also includes an outer surface opposite to the inner surface. The outer surface defines at least one groove. The sealing ring further includes an upper surface extending between the outer and inner surfaces. The upper surface defines a plurality of channels.

Wherever possible, the same reference numbers will be used throughout the drawings to refer to same or like parts.

DETAILED DESCRIPTION

FIG. 1illustrates an exemplary vehicle100incorporating a suspension system102in accordance with the present disclosure. The vehicle100may include a vehicle driven by an internal combustion engine, an electric vehicle, or a hybrid vehicle. The vehicle100includes a body104. The suspension system102of the vehicle100includes a rear suspension106and a front suspension108.

The rear suspension106includes a transversely extending rear axle assembly (not shown) adapted to operatively support a pair of rear wheels110. The rear axle assembly is operatively connected to the body104by means of a pair of dampers112and a pair of helical coil springs114. Similarly, the front suspension108includes a transversely extending front axle assembly (not shown) which operatively supports a pair of front wheels116. The front axle assembly is operatively connected to the body104by means of another pair of the dampers112and a pair of helical coil springs118. In an alternative example, the vehicle100may include an independent suspension unit (not shown) for each of the four corners instead of front and rear axle assemblies.

The dampers112of the suspension system102serve to damp relative movement of the unsprung portion (i.e., the front and rear suspensions108,106) and the sprung portion (i.e., the body104) of the vehicle100. While the vehicle100has been depicted as a passenger car, the dampers112may be used with other types of vehicles or any equipment that requires damping. Examples of vehicles include buses, trucks, off-road vehicles, and so forth. Furthermore, the term “damper” as used herein will refer to dampers in general and will include shock absorbers, McPherson struts, and semi-active and active suspensions.

In order to automatically adjust each of the dampers112, an electronic controller120is electrically connected to the dampers112. The controller120is used for controlling an operation of each of the dampers112in order to provide appropriate damping characteristics resulting from movements of the body104of the vehicle100. Further, the controller120may independently control each of the dampers112in order to independently regulate a damping level of each of the dampers112. The controller120may be electrically connected to the dampers112via wired connections, wireless connections, or a combination thereof. In examples, each of the dampers112may include a dedicated electronic controller that may be located onboard the respective damper112. Further, the functionalities of the controller120may be performed by an Electronic Control Unit (ECU) of the vehicle100.

The controller120may independently adjust the damping level or characteristic of each of the dampers112to optimize a riding performance of the vehicle100. The term “damping level”, as used herein, refers to a damping force produced by each of the dampers112to counteract movements or vibrations of the body104. A higher damping level may correspond to a higher damping force. Similarly, a lower damping level may correspond to a lower damping force. Such adjustments of the damping levels may be beneficial during braking and turning of the vehicle100. The controller120may include a processor, a memory, Input/Output (I/O) interfaces, communication interfaces, and other components. The processor may execute various instructions stored in the memory for carrying out various operations of the controller120. The controller120may receive and transmit signals and data through the I/O interfaces and the communication interfaces. Further, the controller120may include microcontrollers, application-specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), and so forth.

FIG. 2illustrates a cross-sectional view of the damper112. The damper112may be any of the four dampers112of the vehicle100. The damper112may include a Continuously Variable Semi-Active Suspension system (CVSA) damper or a shock absorber, without any limitations. In the illustrated example, the damper112is a double-tube damper. Alternatively, the damper112may include a mono-tube damper. The damper112may contain a fluid which can be a hydraulic fluid or oil. The damper112includes a pressure tube122defining a first end124and a second end126opposite to the first end124. The pressure tube122is embodied as a monolithic pressure tube. The pressure tube122may be further embodied as a substantially cylindrical tube with open ends.

A piston128is slidably disposed within the pressure tube122. The piston128defines a rebound chamber130and a compression chamber132within the pressure tube122. The rebound chamber130is proximal to the first end124, while the compression chamber132is distal to the first end124. Each of the rebound and compression chambers130,132contains the fluid therein. A volume of each of the rebound and compression chambers130,132varies based on a reciprocating motion of the piston128. Additionally, a pair of piston valves (not shown) may be disposed within the piston128to regulate fluid flow between the rebound and compression chambers130,132. More particularly, the piston valves may maintain desired pressures in each of the rebound and compression chambers130,132.

Further, the piston128is connected to the body104of the vehicle100by a piston rod134. The piston rod134is coupled to the piston128. The piston rod134is adapted to reciprocate with the piston128. Further, the piston rod134is partially received within the pressure tube122. The piston rod134extends through the first end124of the pressure tube122. The damper112also includes a piston rod guide assembly136(seeFIG. 3A) disposed proximal to the first end124of the pressure tube122. A movement of the piston rod134is axially limited proximal to the first end124by the piston rod guide assembly136.

In some examples, the damper112may include a base valve (not shown). The base valve may be disposed proximal to the second end126of the pressure tube122. The base valve may allow fluid flow between the compression chamber132and a reserve chamber142. Further, at least one of the piston valves and the base valve may be electronically controlled by the controller120(shown inFIG. 1) such that the controller120may regulate the piston valves and the base valve in order to control the damping level of the damper112.

The damper112also includes a reserve tube138disposed around the pressure tube122. In some examples, the reserve tube138is concentrically disposed around the pressure tube122. The reserve tube138defines the reserve chamber142. Specifically, the reserve chamber142is disposed between the pressure tube122and the reserve tube138. The reserve chamber142may be in fluid communication with an external fluid reservoir (not shown), such as an accumulator. Further, the damper112may include a valve assembly (not shown) that provides fluid communication between the reserve chamber142and the external fluid reservoir. In such examples, the valve assembly may regulate a flow of fluid between the reserve chamber142and the external fluid reservoir. The valve assembly may be electronically controlled by the controller120.

Referring now toFIG. 3A, the damper112includes a hydraulic rebound end stop system300disposed proximal to the first end124of the damper112. The hydraulic rebound end stop system300includes a rebound bumper302, a snap ring304, a first collar306, a sealing ring308, and a second collar307. The damper112includes the rebound bumper302. The rebound bumper302may embody an annular member made from plastic, a polymer, an elastic material, or a metal which defines a through bore (not shown) through which the piston rod134extends. The rebound bumper302may be received within a space140defined between the piston rod134and the pressure tube122. The rebound bumper302surrounds the piston rod134. In an example, the rebound bumper302may be disposed around the piston rod134by a snap fit arrangement. In some examples, the rebound bumper302may be compressed when the piston128moves towards the first end124during the rebound stroke or when the piston128is in a full rebound condition against the rebound bumper302.

Further, the damper112includes the first collar306. The first collar306is disposed around the piston rod134and adjacent to the rebound bumper302. The first collar306is embodied as an annular ring disposed around the piston rod134that defines a through opening (not shown) to receive the piston rod134therethrough. The first collar306includes a planar upper surface (not shown) and a planar lower surface (not shown) disposed opposite to the upper surface. The upper surface faces the rebound bumper302whereas the lower surface faces the sealing ring308. The first collar306may be made of a plastic, a polymer, or a metal. In an example, the first collar306is slidable along an axis “A-A1” defined by the damper112. Moreover, the damper112includes the second collar307that is disposed around the piston rod134and axially spaced apart from the first collar306. The second collar307includes a substantially L-shaped cross-section defining a first portion314, a second portion316, and a through opening (not shown) to receive the piston rod134therethrough. The second portion316of the second collar307contacts an outer surface318of the piston rod134. Further, the second portion316defines an extension320that allows the second collar307to be crimped with the piston rod134for connecting the second collar307to the piston rod134. Thus, the second collar307is fixedly coupled to the piston rod134and does not slide along the axis “A-A1”. The second collar307may be made of a plastic, a polymer, or a metal.

Further, the damper112includes the snap ring304that is disposed adjacent to the second collar307and extends along a circumference of the piston rod134. The snap ring304is at least partially received within a ring groove322of the piston rod134. The ring groove322is defined on the outer surface318of the piston rod134. In an assembled condition of the damper112, the first collar306and the sealing ring308are disposed between the snap ring304and the second collar307, such that the first collar306and the sealing ring308are movable between the snap ring304and the second collar307based on the movement of the piston rod134. The snap ring304is embodied as an annular ring and may be made of a suitable material. For example, the snap ring304may be made of metal or metal alloys.

FIG. 3Billustrates another design of a first collar378associated with the damper112. In this example, the first collar378includes an extending portion380provided on an inner surface of the first collar378. For example, the extending portion may include a ring extending from the inner surface of the first collar378and may be received within a groove382provided on the outer surface318of the piston rod134. In an example, the extending portion380may include a flexible pad. Such an optimized design of the first collar378may eliminate the requirement of the snap ring304(shown inFIG. 3A). Further, the first collar378may also reduce a dead length of the damper112, which may in turn reduce an overall cost of the damper112.

FIG. 3Cillustrates yet another design of a first collar384associated with the damper112. In this example, the first collar384is press-fitted or loose-fitted over a first snap ring386. The piston rod134defines a first ring groove388provided on the outer surface318of the piston rod134. Further, the first snap ring386is received within the first ring groove388. Additionally, a second collar390of the damper112is press-fitted or loose-fitted over a second snap ring392. The piston rod134defines a second ring groove394provided on the outer surface318of the piston rod134. The second snap ring392is received within the second ring groove394. Thus, the second collar390does not include an extension similar to the extension320associated with the second collar307shown inFIG. 3A. Further, the first and second snap rings386,394are similar to the snap ring304illustrated inFIG. 3A. The design of the first and second collars384,390illustrated herein can be used in damper applications with high level topping loads, which may prevent transmission of topping loads to the sealing ring308.

The damper112also includes the sealing ring308slidably disposed around the piston rod134. More particularly, the sealing ring308is slidably disposed around the piston rod134and disposed between the first and second collars306,307. In some examples, the sealing ring308is disposed such that an axial gap (not shown) exists between the sealing ring308and the first collar306to allow some amount of fluid flow through the axial gap. The sealing ring308may be made of a plastic or a polymer.

Referring toFIG. 4A, the sealing ring308defines a through opening324to receive the piston rod134(seeFIGS. 2 and 3) therethrough. Further, the sealing ring308defines an inner surface326. In an assembled condition of the damper112, the inner surface326faces the piston rod134. As shown inFIGS. 4B and 4C, the inner surface326defines an inner diameter “D1”. The inner diameter “D1” is greater than or equal to an outer diameter of the piston rod134(seeFIG. 3A). The inner surface326includes a plurality of concave surfaces328and a plurality of convex surfaces330. Each of the plurality of concave surfaces328is located adjacent to the corresponding convex surface330of the plurality of convex surfaces330. More particularly, the inner surface326includes six concave surfaces328and six convex surfaces330. The inner surface326therefore includes alternating concave and convex surfaces328,330. However, a total number of the concave and convex surfaces328,330may vary as per system requirements. Each concave surface328is curved away from the piston rod134. Therefore, a space is defined between each concave surface328and the piston rod134. Further, each convex surface330is curved towards the piston rod134.

Referring now toFIG. 5, a cross-sectional view of the damper112during the compression stroke is illustrated. During the compression stroke, the sealing ring308may contact the first collar306and may be spaced apart from the second collar307. As illustrated, each of the concave surfaces328defines a first flow path “F1” of fluid within a high pressure region141proximal to the first end124(seeFIG. 2). The high pressure region141may correspond to a region defined in the rebound chamber130with a reduced diameter of the pressure tube122. The reduced diameter may be generated by various processes, such as swaging. Alternatively, the pressure tube122may include a sleeve insert (not shown) instead of the swaged design of the pressure tube122. Each of the concave surfaces328allows fluid flow through the space defined between each concave surface328and the piston rod134. The first flow path “F1” allows fluid flow towards the first end124. More particularly, during the compression stroke, the concave surfaces328allow fluid flow therethrough along the first flow path “F1”.

Further, the concave surfaces328and channels340may allow fluid flow therethrough during the compression stroke and may assist in replenishing the rebound chamber130. Further, when the damper112switches from the compression stroke to the rebound stroke, the concave surfaces328may not allow flow of fluid therethrough along the first flow path “F1” as the first flow path “F1” is restricted by the second collar307. Thus, in such conditions, fluid may flow through the grooves338(seeFIG. 4A) and a bleed path374(seeFIGS. 4C and 4D). Moreover, during the rebound stroke, any fluid flow along the first flow path “F1” may be restricted by the second collar307and fluid may flow only through the grooves338and the bleed path374. Further, the concave surfaces328may provide improved sealing of the sealing ring308against the pressure tube122which may in turn assist in approaching high peak damping forces thereby providing increased energy dissipation.

As shown inFIG. 4A, the sealing ring308further defines a plurality of first segments332spaced apart from each other. In the illustrated example, the sealing ring308includes six first segments332. Each of the plurality of first segments332includes the corresponding concave surface328of the plurality of concave surfaces328. The sealing ring308includes an outer surface336opposite to the inner surface326. As shown inFIGS. 4B and 4C, the outer surface336defines an outer diameter “D2”. The outer diameter “D2” is lesser than or equal to an inner diameter of the pressure tube122(seeFIG. 3A). The outer surface336defines at least one groove338. In the illustrated example, the outer surface336defines a pair of grooves338. However, a total number of the grooves338may vary as per system requirements. It should be noted that the sealing ring308may include a single groove, two grooves, or three grooves based on tunability requirements of the damper112. More particularly, a number of the grooves338and an area of the corresponding groove338may be varied to vary a peak damping force of the damper112. Further, in some examples, the sealing ring308may be designed such that the sealing ring308does not include any of the grooves338.

Referring now toFIG. 6, a cross-sectional view of the damper112during the rebound stroke is illustrated. During the rebound stroke, the sealing ring308may contact the first and second collars306,307. As illustrated, each of the grooves338defines a second flow path “F2” of fluid within the high pressure region141. More particularly, each of the grooves338allows fluid flow through a space between each of the grooves338and the pressure tube122. The second flow path “F2” allows fluid flow towards the second end126(seeFIG. 2). During the rebound stroke, as the pressure in the high pressure region141increases, the grooves338allow dissipation of kinetic energy. Accordingly, the damping force of the damper112increases and the velocity of the piston rod134may reduce thereby allowing reduction in noise. Further, when the damper112switches from the rebound stroke to the compression stroke, the concave surfaces328and the channels340may allow flow of fluid therethrough along the first and third flow paths “F1”, “F3”, respectively. Additionally, when the damper112switches from the rebound stroke to the compression stroke, the grooves338may also allow fluid flow therethrough along the second flow path “F2”. Moreover, during the compression stroke, the grooves338are designed such that the grooves338may allow fluid flow therethrough.

As shown inFIG. 4A, the sealing ring308includes an upper surface334extending between the outer and inner surfaces336,326. The upper surface334defines the plurality of channels340. Each of the plurality of channels340extends from the inner surface326to the outer surface336. Further, each of the channels340defines a third flow path “F3” (shown inFIG. 5) of fluid. Each of the channels340allows fluid flow therethrough. The third flow path “F3” allows fluid flow towards the first end124(seeFIG. 2). More particularly, each of the channels340receives the fluid that exits the space between each concave surface328and the piston rod134along the first flow path “F1”. The fluid flowing along the third flow path “F3” may then exit the sealing ring308and flow towards the first end124. During the compression stroke, the channels340allow dissipation of kinetic energy. Accordingly, the damping force of the damper112increases and the velocity of the piston rod134may reduce thereby allowing reduction in noise. Further, when the damper112switches from the compression stroke to the rebound stroke, the channels340may not allow flow of fluid therethrough along the third flow path “F3” as the third flow path “F3” is restricted by the second collar307. Thus, in such conditions, fluid may only flow through the grooves338and the bleed path374. Moreover, during the rebound stroke, any fluid flow along the third flow path “F3” may be restricted by the second collar307and fluid only flows through the grooves338and the bleed path374.

Further, the sealing ring308defines a plurality of second segments342,368,370spaced apart from each other. In the illustrated example, the sealing ring308includes six second segments342,368,370, each of the plurality of second segments342,368,370being adjacent to the corresponding first segment332of the plurality of first segments332. Further, each of the plurality of second segments342,368,370includes the corresponding convex surface330of the plurality of convex surfaces330, wherein one second segment368or370of the plurality of second segments342,368,370defines the at least one groove338. Specifically, each of the second segments368,370defines the groove338. Further, the convex surfaces330of the sealing ring308allow centering of the sealing ring308. More particularly, the convex surfaces330allow centering of the sealing ring308with respect to the piston rod134. Thus, any misalignment of the sealing ring308with respect to the piston rod134may be eliminated, especially when the damper operates at a high pressure. Further, the convex surfaces330may provide improved sealing of the sealing ring308against the pressure tube122.

Further, each of the plurality of second segments342,368,370includes a top surface344and a bottom surface346opposite to the top surface344. The at least one groove338extends from the top surface344to the bottom surface346of the one second segment368,370. The bottom surface346may be substantially planar. In the illustrated example, the at least one groove338includes the plurality of grooves338defined on the outer surface336of the sealing ring308. Each of the plurality of grooves338is defined by the corresponding second segment368,370of the plurality of second segments342,368,370. Moreover, each of the plurality of second segments342,368,370includes the top surface344and a pair of lateral surfaces348,350extending upwardly from opposing sides of the top surface344. Each of the plurality of channels340is defined by the top surface344and the pair of lateral surfaces348,350of the corresponding second segment342,368,370of the plurality of second segments342,368,370. Each channel340is substantially U-shaped. The sealing ring308also includes a third segment352disposed between two of the second segments342. The third segment352includes a pair of concave surfaces354,356and a convex surface358disposed between the pair of concave surfaces354,356. Each of the concave surfaces254,356also defines a space through which fluid can flow during the rebound and compression strokes. Further, the convex surfaces358assist in centering of the sealing ring308.

The sealing ring308further includes a locking mechanism360adapted to lock the sealing ring308around the piston rod134. The locking mechanism360is disposed diametrically opposite to the third segment352. The locking mechanism360includes a first tongue362and a second tongue364. The first tongue362is adapted to engage with the second tongue364to lock the sealing ring308around the piston rod134. Further, the locking mechanism360includes a projection366extending substantially parallel to the upper surface334of the sealing ring308. As shown inFIG. 4D, the projection366is disposed below the first tongue362and the second tongue364. More particularly, the projection366defines a land that is disposed beneath the locking mechanism360. The projection366minimizes a leakage of fluid through a leakage path372that exists between the first and second tongues362,364. The projection366covers the leakage path372from below such that leakage of fluid is minimized.

The locking mechanism360also defines a bleed path374. Further, the locking mechanism360includes a leakage prevention feature376(shown inFIG. 4C). The leakage prevention feature376eliminates any axial or radial leakage of fluid therethrough, thereby eliminating leakage of fluid through the bleed path374. In an example, the leakage prevention feature376may include a first tab that couples with a second tab to seal the bleed path374. It should be noted that the leakage prevention feature376described herein is exemplary in nature, and the leakage prevention feature376may include any other design features that allow sealing of the bleed path374. The locking mechanism360is designed such that unintentional opening of the sealing ring308due to high hydraulic pressures during the operation of the damper112is eliminated.

The design of the sealing ring308associated with the damper112explained above may include a simplified construction and robust design and may be easy to manufacture. Further, the sealing ring308described above may be incorporated in the damper112at a lower cost as compared to existing sealing rings. The sealing ring308may improve durability and tunability of the hydraulic rebound end stop system300. This design of the sealing ring308may be repeatable and consistent in performance. Additionally, an application of the damper112described herein is not restricted to vehicles and may be used in any application that incorporates a damper112.

Referring toFIG. 2, as the piston128travels towards the first end124during the rebound stroke, the volume of the compression chamber132increases and the volume of the rebound chamber130decreases. As shown inFIG. 6, during the rebound stroke, the sealing ring308is held between the first collar306and the second collar307and any fluid flow along the first and third flow paths “F1”, “F3” (seeFIG. 5) is restricted. Further, due to decrease in the volume of the rebound chamber130, the pressure in the rebound chamber130increases. As the pressure in the rebound chamber130increases, the sealing ring308allows controlled flow of fluid through the second flow path “F2” within the high pressure region141. During the rebound stroke, the second flow path “F2” directs the fluid flow towards the second end126(seeFIG. 2). Further, as the piston128moves from the rebound stroke to the compression stroke, the concave surfaces328, the grooves338, and the channels340may allow fluid flow therethrough.

Referring toFIG. 5, during the compression stroke, the upper surface334(seeFIG. 4A) of the sealing ring308is in contact with the lower surface of the first collar306. Further, an axial gap is defined between the sealing ring308and the second collar307. During the compression stroke, the sealing ring308allows controlled flow of fluid through the first and third flow paths “F1”, “F3” towards the first end124(seeFIG. 2). More particularly, the concave surfaces328and the channels340allow fluid flow therethrough along the respective first and third flow paths “F1”, “F3” within the high pressure region141. Additionally, during the compression stroke, the grooves338are designed such that the grooves338may also allow fluid flow therethrough. As the piston128moves from the compression stroke to the rebound stroke, the concave surfaces328and the channels340may not allow fluid flow therethrough along the first and third flow paths “F1”, “F3”, respectively, as the flow paths “F1”, “F3” are restricted by the second collar307.

The sealing ring308allows controlled flow of fluid through the first, second, and third flow paths “F1”, “F2”, “F3” (seeFIGS. 5 and 6) to dissipate some amount of kinetic energy thereby eliminating any hard stop of the piston rod134. More particularly, provision of the concave surfaces328, the grooves338, and the channels340(seeFIG. 4A) allow dissipation of kinetic energy. The dissipation of kinetic energy causes reduction in the velocity of the piston rod134thereby allowing reduction in noise generated by the damper112as well as reduction of forces experienced by various components of the vehicle.

FIG. 7is an exemplary plot700illustrating peak rebound forces for a sealing ring308(seeFIG. 4A) having different groove areas that is defined by grooves formed on the sealing ring308. Exemplary groove areas in terms of square millimeters (mm2) is marked on the X-axis whereas peak damping forces in terms of kilonewton (kN) is marked on the Y-axis. The plot700is prepared by plotting results for the different groove areas. More particularly, the pattern702is generated by plotting points “P1”, “P2”, “P3”, “P4” corresponding to different groove areas. As illustrated, the point “P1” corresponds to the sealing ring308with no grooves, thus the groove area is zero. Further, the point “P2” corresponds to the sealing ring308with a single groove, the point “P3” corresponds to the sealing ring308with two grooves, whereas point “P4” corresponds to the sealing ring308with three grooves. It can be concluded that as the groove area and/or number of grooves increases, the peak damping force of the damper112decreases. The number and/or area of the grooves may be tuned or adjusted as per application requirements.

FIG. 8is an exemplary plot800illustrating benchmark comparison between two different sealing rings. The plot800is generated by moving the piston rod134at a desired velocity and displacing the piston rod134by a desired displacement beyond a full rebound condition of the damper112. Exemplary displacement of the sealing rings in terms of millimeters (mm) is marked on the X-axis whereas peak damping forces in terms of kilonewton (kN) is marked on the Y-axis.

The plot800is prepared by plotting results for two different sealing rings. More particularly, the pattern802is generated by plotting points corresponding to the sealing ring308shown inFIG. 4Awhereas the pattern804is generated by plotting points corresponding to a conventional sealing ring. For pattern802, point “P5” represents a hydraulic rebound end stop initial rate whereas point “P6” represents a hydraulic rebound end stop final rate. More particularly, the hydraulic rebound end stop initial rate and the hydraulic rebound end stop final rate correspond to an initial velocity and a final velocity, respectively, of the piston rod134that may be controlled based on the design of the sealing ring308in order to achieve desired tunability.

It can be concluded that at similar velocity of the piston rod134and similar piston rod displacement, the sealing ring308corresponding to the pattern802exhibits greater peak damping forces as compared to the sealing ring corresponding to the pattern804. Further, energy dissipated by the damper112is represented by an area806. Accordingly, it can be concluded that the energy dissipated by the damper112having the sealing ring308is greater than energy dissipated by the damper112having the conventional sealing ring.