Compliant elastomeric shock absorbing apparatus

A shock absorbing apparatus includes a flexible membrane defining an accumulator cavity, and a compression assembly defining a compression cavity. The compression assembly is disposed within the flexible membrane such that viscous fluid contained within the cavities may be exchanged therebetween by a damping orifice, fluid conduit and or valve mechanism. The accumulator cavity deforms in response to the application of a transmitted impact load, and is capable of storing and releasing potential energy in response to the application and cessation of the transmitted impact load.

TECHNICAL FIELD

This application is generally directed to the field of energy absorption apparatus and more specifically to a shock absorbing apparatus that employs a highly flexible housing containing a quantity of hydraulic fluid. The housing is defined by at least one elastomeric membrane to limit forces transmitted to the surroundings of an attached structure, but without requiring dynamic hydraulic seals or separate spring biasing apparatus.

BACKGROUND

There are several types of apparatus that can be employed for industrial and structural uses in order to absorb energy, such as from a transmitted load. For example, high cycle blow molding apparatus employ mold or die halves which can “bounce” as a consequence of opening and closing the dies, i.e., principally the impact of closing the dies. Such bounce can produce defects in the molded product resulting in increased scrap, additional maintenance and increased downtime of the blow molding apparatus. Consequently, the throughput/efficiency of the blow molding apparatus is adversely impacted. To alleviate difficulties associated with the foregoing, conventional shock absorbers have been employed to convert the impact energy of the bounce as dissipated heat.

More specifically, these shock absorbers typically include at least one piston assembly, which is disposed within an enclosed cavity or housing, and coupled to the machine under load. In operation, a transmitted shock or impact load creates: (i) movement of the piston assembly, (ii) a change in pressure of a contained incompressible hydraulic fluid in the cavity, and (iii) flow through at least one orifice that results in conversion of the applied kinetic energy to heat. The force of the transmitted shock or impact load is reduced by the shock absorber, thereby lowering the transmitted load from other parts of the machine or other attached structure.

For proper operation, shock absorbers as described above require at least one dynamic seal interposed between the moving parts to prevent fluid leakage, and/or the ingestion of air into the hydraulic cavity of the housing. Inasmuch as blow molding or other apparatus routinely undergo a high number of cycles, it is common for the dynamic seals to fail prematurely, requiring costly repair and maintenance. Additionally, the replacement of either the hydraulic seals, or the entire shock absorber assembly, can adversely impact manufacturing schedules or other time-critical events for the purpose of repairing and/or replacing the affected assemblies. It will be appreciated that avoiding down-time for such high throughput machines is an ongoing and important goal.

It is, therefore, desirable to provide an effective and reliable shock absorbing apparatus which mitigates the need for dynamic seals and the failure modes associated therewith. Furthermore, it will be appreciated that there is a competing and prevalent need to reduce complexity, improve reliability, and lower associated costs of such high cycle, dynamic shock absorbing apparatus.

BRIEF DESCRIPTION

Therefore and according to one embodiment, a shock absorbing apparatus comprises a flexible membrane defining an accumulator cavity and a compression assembly defining a compression cavity. The compression assembly is disposed within the flexible membrane such that a viscous fluid may be exchanged between the accumulator and compression cavities via a fluid conduit, damping orifice and/or one or more valve mechanisms. The accumulator cavity deforms in response to the application of a transmitted impact load, and is capable of storing and releasing potential energy in response to the application and cessation of the transmitted impact load.

The compression assembly includes a stationary guide and a reciprocating piston slideably mounted to the stationary guide. The compression assembly is operative to: (i) develop a first pressure differential, in response to the application of the transmitted impact load, for displacing the viscous fluid through a damping orifice from the compression cavity to the accumulator cavity, and (ii) develop a second pressure differential to restore the viscous fluid to the compression cavity from the accumulator cavity.

In yet another embodiment, the compression assembly includes a stationary shock tube for slidably mounting a reciprocating piston to an internal wall surface of the shock tube. The reciprocating piston and stationary shock tube, furthermore, define the compression cavity wherein the piston is responsive to the application of the transmitted impact load. Furthermore, the reciprocating piston is displaced by the flexible membrane to move a quantity of viscous fluid through the damping orifice.

In a further embodiment, the compression assembly includes a stationary strut for slideably mounting a reciprocating piston to an external wall surface of the stationary strut. The reciprocating piston and stationary strut, furthermore, define the compression cavity wherein the piston is responsive to the application of the transmitted impact load. Additionally, the reciprocating piston is displaced by the flexible membrane to move a quantity of viscous fluid through the damping orifice.

According to another embodiment, a shock absorbing apparatus is provided comprising a flexible housing substantially formed from at least one fluid-impermeable elastomeric section and defining an interior. A plate disposed within the interior of the housing has at least one orifice, the plate creating adjacent chambers containing a hydraulic fluid that are fluidically connected by the at least one orifice. At least one mounting plate connects the housing to a structure or machine that is under load. Transmitted shock loads from the structure causes the elastomeric housing to be pressurized, as well as the contained hydraulic fluid, causing the pressurized fluid to move through the at least one orifice to provide energy dissipation through viscous damping.

In at least one version, the flexible housing can be defined by at least one elastomeric section bonded to at least one support plate. In at least one embodiment, a pair of housing portions are provided, each having at least one elastomeric section bonded to a mounting plate and a striker plate, respectively. In one version, a single orifice is defined in a center plate although this number can be suitably varied and sized to enable damping characteristics to be suitably tuned.

In another optional version, at least one shaped pin member can be provided to define a variable orifice diameter wherein the pin member can be defined by a tapered configuration that effectively reduces the flow area when the pin member is moved into the orifice while under load. In addition and according to at least one embodiment, at least one spring can be provided within the defined housing to provide an additional biasing force along with the restoring force provided by the flexible elastomeric housing and also to prevent a compressive set.

According to another embodiment, the herein described shock absorbing assembly can be configured to receive impact or shock loads at respective ends of the defined flexible interchangeable according to a housing, and in which a biasing spring can be provided in each fluidic chamber in the housing interior such that the adjacent fluid chamber and accumulation chambers are symmetric.

According to another aspect, there is provided a method for manufacturing a shock absorbing apparatus without requiring sliding hydraulic seals, the method comprising: (i) bonding outer ends of a first elastomeric section to a mounting plate to create a first housing section; (ii) bonding outer ends of a second elastomeric section to a mounting plate to create a second housing section; and (iii) mounting a plate between the first and second housing sections, the plate having at least one orifice; (iv) connecting the two housing sections together to form an enclosed flexible housing, the orifice plate being sandwiched between the mounting plates and extending through the defined housing; (v) adding hydraulic fluid to the interior of the defined housing; and (vi) attaching each of the mounting plates of the housing to a structure under load, wherein impact loads to the housing cause a pressure differential between the defined fluid chambers, to further cause movement of the contained hydraulic fluid between defined fluidic chambers through the at least one orifice in order to effect damping and a restoring spring.

In one version, the fluidic chambers can be defined using a fixed plate that is disposed within the interior of the flexible housing, in which the fixed plate further includes the at least one orifice. One or more orifice holes can be sized and configured for a desired damping level when fluid is caused to pass therethrough.

Each end of the defined housing, in at least one version, can include at least one striker or contact plate that is axially aligned at an end of the flexible housing with the defined orifice that is configured to effect damping in response to an applied load.

At least one pin member can also be optionally added to the interior of the housing, the pin member having a tapered configuration that can be translated axially into and out of the orifice based on loading conditions, and thereby creating a variable orifice diameter. For example and according to one version, the pin member is assembled using fasteners to the striker plate and reduces the effective flow area when moved into the orifice. In at least one version, a pair of tapered pin members can be provided, each of these members being axially and symmetrically aligned with one another.

In addition, at least one spring can also be optionally included within the interior of the housing and more specifically within each of the defined fluidic chambers in order to additionally provide a biasing or restoring force along with the elastomeric material of the housing and/or to prevent compression of the herein described apparatus.

According to at least one other aspect, there is provided a shock absorbing apparatus comprising a flexible housing having an interior, a first housing portion including a fluid impermeable elastomeric section having outer ends bonded to a first base plate and a first striker plate; and a second housing portion including a fluid impermeable elastomeric section having outer ends bonded to a second base plate and a second striker plate. The apparatus further comprises a plate disposed between the first and second housing sections, the plate having at least one orifice, the plate defining adjacent interior fluidic chambers fluidically connected by the orifice that contain a hydraulic fluid, wherein impact loads to a striker plate causes pressurization and movement of the contained hydraulic fluid between defined fluidic chambers through the at least one orifice in order to effect shock absorption relative to a connected structure.

Advantageously, the herein described shock absorbing apparatus is simpler and easier to assemble than prior known versions based on a fewer number of required parts. The herein described shock absorbing apparatus performs reliably, but without requiring reciprocating piston assemblies and associated hydraulic sliding seals. As a result, the herein described apparatus has a longer overall service life as compared to prior designs, and particularly in working environments that are usually characterized by frequent or high loading cycles.

In addition, the herein described apparatus is relatively easy and inexpensive to manufacture as compared to prior art versions. For example, aspects of the housing can be injection molded according to at least one version. In addition, the herein described apparatus is simple in terms of assembly and also for purposes of mounting to a specified structure or machine that is under load for purposes of shock absorption.

For manufacturing purposes, the same mold can be used with various durometer/hardness properties of elastomer to provide stiffness variation. Similarly, different orifice sizes can utilize the same plate “blank”. This allows the same components and manufacturing process/tools to be used for multiple applications of the herein described apparatus.

DETAILED DESCRIPTION

The following relates to certain embodiments of a shock absorbing apparatus that relies upon at least one elastomeric element or membrane to define a highly flexible housing containing a hydraulic fluid that can be attached to a structure or machine under load. The apparatus reliably reduces transmitted shock loads from other parts of a machine or other structure. In one embodiment, a reciprocating piston or piston assembly is eliminated along with the requirement for dynamic seals. In other embodiments, a compression assembly is fully immersed within, or enveloped by, a flexible membrane or housing. In these embodiments, immersion of the compression assembly allows for a degree of fluid leakage or passage from one cavity to an adjacent cavity.

In certain embodiments, the shock absorbing apparatus reduces transmitted shock loads without the requirement for sliding dynamic seals to move a hydraulic fluid through a damping orifice and/or separate spring biasing elements to return the elastomeric membrane to its original shape/configuration for subsequent work cycles. As such, the hydraulic shock absorbing apparatus of the present disclosure is particularly advantageous for use in environments characterized by high cyclic loading such as, for example, blow molding apparatus for fabricating plastic containers/bottles. It will also be readily apparent that the shock absorbing apparatus described herein can be employed for nearly any application that requires impact and/or shock load absorption.

For background purposes, reference is made toFIG. 1which depicts a typical shock absorbing apparatus100comprising a piston assembly106disposed within, and supported by, a cylinder120containing a hydraulic damping fluid108. More specifically, the piston assembly106includes a piston head110, at one end, disposed within, and acting against, the hydraulic damping fluid of the hydraulic cylinder120, and a cylindrical piston rod114, at an opposing end, connected to the piston head110.

In operation, the piston assembly106moves with, and is responsive to, a transmitted impact or shock load of the blow molding apparatus while the cylinder120is attached to a fixed support, or another portion, of a machine. More specifically, the transmitted shock or impact load causes axial movement of the piston assembly106, including the piston head110against the hydraulic fluid, pressurizing same and causing movement of the fluid though at least one defined orifice130to an accumulator136. This movement results in a reduction in transmitted force to the remainder of the connected structure as the energy of the shock load is dissipated over the stroke of the unit, i.e., as heat generated by the shearing action of the hydraulic fluid. The piston assembly106is configured to move axially in a reciprocating fashion in response to the transmission and cessation of load while a biasing coil spring128stores a portion of the kinetic energy of the piston assembly106as potential energy in the coil spring128. With each cycle, the impact load displaces the piston head110so as to force the damping fluid through the damping orifice130in the piston head110. With the cessation of the impact load, the coil spring128is operative to return the piston assembly106of the shock absorbing apparatus100to its initial or original position. To prevent leakage of the contained pressurized hydraulic fluid during movement of the piston head110, a dynamic (frictional) seal140is provided. Under conditions typified by high cyclic loading, this dynamic seal140is prone to failure. Consequently, shock absorbing apparatus of the prior art require frequent replacement which adversely impacts throughput and machine efficiency.

Referring toFIGS. 2 and 3, a shock absorbing apparatus200in accordance with an exemplary embodiment is defined by a flexible housing204that is made substantially from a fluid-impermeable elastomeric material. According to this specific embodiment, the shock absorbing apparatus200is defined by a pair of housing portions206,208, as well as an orifice plate212. Each of the housing portions206,208are commonly defined by a section210of an elastomeric material of suitable shape, in this instance circular, and in which each elastomeric section210has an outer periphery217that is bonded to the inner peripheral edge of a mounting plate216. It will be understood that the shape assumed for the mounting plates216and elastomeric sections210is exemplary and other configurations could be contemplated.

An inner periphery219of each elastomeric section210is further bonded to a striker plate220. When assembled, each of the bonded elastomeric sections210of the housing portions206,208form a complementary and substantially C-shaped configuration in which the mounting plates216each extend radially from the elastomeric section210and in which the striker plate220forms the center of each outwardly bowed housing portion206,208. In this embodiment, each of the housing portions206,208, including the elastomeric material section210, are identical. It should be noted, however, that each housing portion206,208could be configured with different material characteristics. For example, the thickness, shape and or material of the elastomeric sections of the first and second housing portions206,208can be varied from one another in order to produce different responses under load. In the described embodiment, the flexible elastomeric sections may be fabricated from a rubber material, including natural rubber, fluoroelastomer, fluorosilione, silicone, EPDM, butyl rubber, nitrile rubber and the like. The flexible elastomeric material employed therein may have a shear modulus greater than about 4.35×105psi, a bulk modulus greater than about 2.2×105psi, a maximum elongation greater than about 100% from an original size/length, and a durometer of between about between about thirty (30) to about seventy (70) on a Shore A hardness scale.

Each mounting or support plate216according to this embodiment is formed as a substantially planar section made from a suitable metal, plastic or elastomeric material, provided each of the plates can provide structural support. In at least one version, each of the mounting plates216could also be made from an injection molded plastic. The mounting plates216are defined by an inner peripheral end and an opposing outer peripheral end with a circular opening being formed at the center of each mounting plate216which is bounded by the inner peripheral edge of the mounting plate216. An annular groove226is formed on an opposing surface of each mounting plate216at the peripheral inner end relative to the bonded elastomeric section210. The bonding of the elastomeric sections210to the striker and base plates216,220can utilize adhesives, activated during the molding process, or as a post-molding standalone agent that creates or otherwise creates a durable fluid-tight seal. According to this embodiment, the annular groove226of each housing portion206,208is configured to receive an O-ring229or other form of static sealing member.

The striker plates220are made from a durable material, such as a thermoset wear-resistant plastic and are commonly defined by a substantially cylindrical configuration. Each striker plate220is sized to substantially correspond with the thickness of the solid elastomeric section210and includes a center through opening224sized to receive a fastener228, such as a counter sunk fastener, the fastener228having a length that extends into the interior240of the housing204when attached, as shown inFIG. 3. Each of the two mounting plates216and the sandwiched orifice plate212are defined by an aligned series of mounting holes230which are exterior to the formed flexible housing204. The mounting holes230enable attachment of the flexible housing204to a structure or machine (not shown) using fasteners (not shown). It should be noted that this embodiment depicts striker or impact plates220as part of each housing portion206,208. Alternatively, only one of the housing portions can be provided with a striker or impact plate220.

The orifice plate212according to this exemplary embodiment is defined by a planar member made from plastic, metal, composite or other durable material that is sized and configured to extend through the interior of the defined housing204with the outer end of the orifice plate212being sized to complement the mounting plates216, including the mounting holes230. At least one orifice238formed at substantially the center of the orifice plate212is axially aligned according to this embodiment with the through openings224of the striker plates220, when assembled. The orifice plate212divides the hollow interior240of the housing204into adjacent substantially hemispherical chambers242,246that are fluidically interconnected by the defined orifice238. In the context used herein, “fluidically” means a fluid connection, or the type of connection, between two portions, cavities or chambers of the hydraulic shock absorbing apparatus, i.e., that the cavities are in fluid communication. Though only a single orifice238is provided according to this embodiment, one or more orifice(s) can be suitably provided and sized in order to effectively tune the amount of damping required. According to this embodiment, the orifice plate212further includes a pair of outwardly extending annular rings234radially exterior to the housing204that are sized and configured to fit within corresponding grooves237which are formed within the inner facing side of a corresponding mounting plate216to further retain the assembly200in a press fit. Following the above described press fit assembly of the housing portions206,208, a quantity of hydraulic fluid250can be added to the hollow interior240of the housing204. According to this embodiment, the hydraulic fluid250can be added to the through opening224formed in one of the striker plates220, forming a sealable fill port, and prior to attaching the fastener228.

According to this specific embodiment and still referring toFIGS. 2 and 3, at least one pin member252can be optionally disposed within the hollow interior240of the defined housing204. More specifically and according to this exemplary embodiment, a pair of hollow pin members252can optionally be provided, each pin member252having a conical tapered configuration defined by a distal end opening254having a first diameter and a proximal end opening256having a second diameter that is larger than the first diameter. According to this exemplary embodiment, the pin members252each include a proximal opening258,FIG. 2, that receives the extending end of fasteners228at each end of the housing204. When positioned in the manner shown inFIG. 3, the application of a transmitted axial load284to the housing204will cause the pin members252to be moved into the orifice238, thereby reducing the effective flow area and creating a variable orifice diameter.

In addition, a pair of springs266can be optionally provided in the hollow interior240and aligned with the orifice238and the striker plates220in order to provide a biasing or restoring force in addition to that of the elastomeric housing204. In this embodiment, each of the springs266are mounted between the striker plate220and the orifice plate212in each respective fluidic chamber242,246with the pin member252extending through the center of the spring266. According to this specific embodiment and when assembled, the springs266are axially aligned with the orifice238, as well as the center openings224of each striker plate220and with the spring ends being in engagement between a striker plate220and the orifice plate212in each defined fluidic chamber242,246.

Fasteners (not shown) from a machine or other structure, such as threaded or other forms of fasteners, secure the herein described optional assembly through the aligned openings230of the mounting plates216and the sandwiched orifice plate212, thereby fixedly attaching the assembly to a structural component.

In operation and still referring toFIGS. 2 and 3, the herein described shock absorbing apparatus200can be disposed between respective die portions of a blow molding machine (not shown) and mounted using fasteners attached through the aligned holes230of the mounting plates216and the orifice plate212. As attached, one of the striker plates220is aligned in relation to the movable die portion (not shown) of the machine. As the die is closed, the die engages the striker plate220as depicted by arrow284, generating a compressive load against the flexible elastomeric housing204and more specifically the elastomeric section210of the housing204. This causes an inward deformation of the flexible housing204, resulting in the hydraulic fluid250contained in the first fluidic chamber242to be pressurized and forced through the orifice238and into the adjacent second fluidic chamber246with the optional tapered pin member252also being advanced into the orifice238based on the application of load.

The shearing of the contained fluid250through the orifice hole(s) and the flexion of the herein described elastomeric housing204acts to convert the energy of the applied load from the machine into heat that is dissipated to the environment. Following the application of load, the elastomeric nature of the housing204provides a restoring force to revert the housing204to its original shape in the direction of arrow288, with the hydraulic fluid250being restored to the fluidic chamber242and under the additional biasing force of the optionally provided springs266.

Another version of the herein described shock absorbing apparatus is illustrated inFIGS. 4 and 5, and as used in conjunction with a testing structure390, partially shown). According to this specific embodiment, the shock absorbing apparatus300is defined by a flexible housing304that is made from a pair of housing portions that are fastened together and sealed. Each of the housing portions, similar to the preceding embodiment, include the elastomeric section310that is attached, such as by bonding or other suitable means, to a mounting or support plate316and a striker plate320, respectively, the latter having a fastener328extending into the interior of the housing304. The latter mounting plates316are attached to one another using fasteners394or the like to opposing sides of the testing structure390.

According to this embodiment, the mounting plates316are made from a metallic material having a bonded elastomeric material such as silicone, though other suitable materials could be utilized that provide structural integrity, flexibility as well as being fluidically impermeable. In the described embodiment, the flexible elastomeric material may be fabricated from a rubber material, including natural rubber, fluoroelastomer, fluorosilione, silicone, EPDM, butyl rubber, nitrite and the like. The flexible elastomeric material may have a shear modulus greater than about 4.35×105 psi, a bulk modulus greater than about 2.2×105 psi, a maximum elongation greater than about 100% from an original size/length, and a durometer of between about thirty (30) to about seventy (70) on a Shore A hardness scale.

A pair of adjacent fluidic chambers342,346(shown in phantom inFIG. 5) are defined within a hollow interior of the herein described damping apparatus300and into which a quantity of hydraulic fluid is added, such as through an opening in the striker plate320formed at one end of the defined housing304. The adjacent fluidic chambers342,346are separated from one another and fluidically connected by a fixed orifice plate312, disposed within the interior of the housing304, the latter of which having at least one defined orifice or through opening (not shown) and in which the orifice plate312is also secured using fasteners or other suitable means to the mounting plates316in a clamped configuration.

In operation, the shock absorbing apparatus300is attached to the testing fixture390using fasteners394secured through openings formed in the mounting and support plates316. Hydraulic fluid is added to the hollow interior of the housing304through the fill port at the end of the housing304in which a plug such as the fastener328secures the port after filling. When acted upon by an axial load directed against the striker plate320, the highly flexible housing304and more specifically the elastomeric material310of the housing304is caused to deform inwardly, which decreases the internal volume of the housing304and more specifically chamber342. This reduction causes contained hydraulic fluid to also be pressurized and forced into the confines of the adjacent fluidic chamber through the defined orifice in order to provide shock absorption.

Referring toFIGS. 6 and 7, a shock absorbing apparatus400in accordance with another embodiment comprises: (i) a flexible elastomeric element or membrane404defining a compliant accumulator cavity442which deforms in response to the application or cessation of a transmitted impact load S, and (ii) a compression assembly406defining a rigid, compression cavity446operative to move or displace a contained viscous fluid450through at least one damping orifice430from the compression cavity446to the compliant accumulator cavity442. In the described embodiment, the compression assembly406is at least partially enveloped or enclosed by the flexible elastomeric membrane404such that viscous fluid contained within each of the compliant accumulator or rigid compression cavities442,446may be exchanged. More specifically, the compression assembly406is operative to create a first pressure differential by which: (i) a first pressure is developed in the compression cavity446, in response to the application of the transmitted impact load S, and (ii) a second pressure, lower than the first pressure, is developed in the compliant accumulator cavity442. This pressure differential causes displacement of a quantity of viscous fluid450through the damping orifice430from the compression cavity446to the compliant accumulator cavity442, while elastically deflecting or deforming the flexible elastomeric element or membrane404. Upon cessation of the impact load S, the first pressure within the compression cavity446reduces to zero and a second pressure differential is then created in which a quantity of contained viscous fluid450is then displaced from the compliant accumulator cavity442through a conduit408and the damping orifice430to the compression cavity446. This latter movement of fluid restores the compression cavity406to its fully extended state.

In the embodiment depicted inFIG. 6, the compression assembly406may include: (i) a reciprocating input member or piston410, (ii) a stationary piston guide412, and (iii) a valve mechanism414disposed in combination with the reciprocating input member410and operative to refill or restore a quantity of the viscous fluid450from the accumulator cavity442to the compression cavity446. With respect to the latter, the valve mechanism414prepares or readies the compression assembly406for a subsequent work cycle by allowing the fluid to flow through a conduit408which fluidically connects the cavities442,446. The cooperation between the various elements will be further discussed in greater detail.

The flexible elastomeric element or membrane404is positioned beneath the transmitted impact load S such that the elastomeric membrane404is displaced or deformed in one direction as a consequence of the application of the impact load S. Furthermore, as will be discussed in greater detail hereinafter, the flexible elastomeric membrane404stores at least a portion of the transmitted impact load S, such that in the absence of the impact load S, the flexible elastomeric membrane404returns to its original size and/or shape so as to be readied for the next work cycle. That is, the flexible elastomeric membrane404stores a portion of the energy required to displace the flexible membrane404as potential energy in the elastomeric material. The stored energy, which is principally stored as tension in the elastomeric material (i.e., similar to the way a balloon expands to store the energy as compressed air/potential energy in the high elongation rubber) may be released when the transmitted impact load S either changes direction or is periodically released with each cycle.

In the described embodiment, the elastomeric membrane404may be sealed, at one end, to a mounting plate416and, at another end, to an impact plate420. In the described embodiment, the impact plate420may be integrated with the flexible elastomeric membrane404such that it may transmit shock loads S from a blow molding apparatus (not shown) or other transmission source. The seals at the first and second ends404a,404bof the flexible elastomeric membrane404, may be permanently bonded, fused, or molded in combination with the mounting plate416and/or with the impact plate420. When bonding the flexible elastomeric membrane404to the mounting or impact plates416,420, a conventional adhesive may be used, either activated during the molding process, or as a post-molded sealing agent that creates or otherwise forms a durable fluid-tight seal. Alternatively, the flexible elastomeric membrane404may be stretched over an edge, annular lip or groove of the mounting or impact plates416,420and captured by an annular compression/sealing ring (not shown). Alternatively still, the impact plate420may be integrated with the compression assembly406, i.e., the upper portion of the reciprocating piston410, or simply bonded over an external surface of the flexible elastomeric membrane404. With respect to the latter, the compression assembly406may be disposed beneath and aligned with the impact plate420such that the flexible membrane404is sandwiched between the impact plate420and the compression assembly406.

In the described embodiment, the flexible elastomeric membrane404defines a selectively-shaped compliant vessel, e.g., cup, bell, or dome-shaped, which produces a desired spring rate stiffness. It will be appreciated that the stiffness of the flexible elastomeric membrane404will be a function of various factors, including, inter alia, the wall thickness of the elastomeric membrane404, the shear and bulk modulus of the elastomeric material, and the durometer and/or elongation properties. These and other properties determine the ability of the flexible elastomeric membrane404to: (i) react transmitted shock loads S acting on the striker plate420, and (ii) return the impact plate420to its original position or to a ready position, i.e., so that the flexible elastomeric membrane404can perform work for a subsequent cycle. It will be understood that the shape, thickness, and volume occupied by the flexible elastomeric membrane404is merely exemplary and other configurations are contemplated.

In the described embodiment, the flexible elastomeric membrane404may be fabricated from a rubber material, including natural rubber, fluoroelastomer, fluorosilione, silicone, EPDM, butyl rubber, nitrite and the like. The flexible elastomeric membrane404may have a shear modulus greater than about 4.35×105psi, a bulk modulus greater than about 2.2×105psi, a maximum elongation greater than about 100% from an original size/length, and a durometer of between about between about thirty (30) to about seventy (70) on a Shore A hardness scale.

As previously mentioned, the flexible elastomeric membrane404defines a compliant accumulator cavity442which contains a specific volume of a viscous fluid450therein. The viscosity of the fluid is tied/related to the size of the damping orifice430and the desired damping effect produced by the shock absorbing apparatus400. For the requirements of the present shock absorbing apparatus400, the viscosity of the fluid is greater than about twenty centipoise (20 cP).

The flexible elastomeric membrane404, furthermore, occupies a volume sufficient to envelop, circumscribe, or enclose the compression assembly406which, as mentioned supra, includes the reciprocating input member or piston410, the piston guide412and the valve mechanism414. More specifically, the compression assembly406is disposed between the stationary mounting plate416and the moving impact plate420to pump or move viscous fluid450through the damping orifice430in response to transmitted impact or shock loads S. Furthermore, the compression assembly406is responsive to: (i) the deformation of the flexible elastomeric membrane404, (ii) the displacement of the impact plate420relative to the mounting plate416, (iii) and the energy storage capacity of the flexible elastomeric membrane404to store at least a portion of the energy of the impact load S. With respect to the latter, it will be appreciated that the flexible elastomeric membrane404converts kinetic energy into potential energy for the purpose of returning the elastomeric membrane404to its original shape/size while, at the same time, returning the impact plate420to its original position. This, in turn, prepares or readies the shock absorbing apparatus400for another work cycle. In the described embodiment, the stationary guide412may include a shock tube422having a first end424sealably affixed to the mounting plate416by a base plate418which connects the shock tube422to the mounting plate416. More specifically and according to this embodiment, the first end424of the shock tube422is welded, bonded or fused to the base plate418such that the elongate axis of the shock tube422is orthogonal to the base plate418and parallel to the direction of the transmitted shock load S. Alternatively, the shock tube422and first end424could be machined from the same piece.

In the illustrated embodiment, the base plate418may be riveted to the mounting plate416such that an edge of the flexible elastomeric membrane404, i.e., the second end thereof, is captured between the mounting and base plates416,418. More specifically and according to this specific embodiment, a plurality of equiangularly-spaced rivets428are disposed about a mounting hole aperture432to sealably mount the base plate418to the mounting plate416. InFIG. 7, the mounting plate416may include a female-threaded sleeve436projecting traversely from the underside of the mounting plate416. In this embodiment, the base plate418includes a female-threaded sleeve438engaging the male-threaded sleeve436and a sealing O-ring (not shown) interposing the male and female-threaded sleeves436,438. The sealing O-ring may be captured in an annular groove machined or formed in one of the male and/or female-threaded sleeves436,438.

Each mounting and base plate416,418according to this embodiment is formed as a substantially planar section made from a suitable metal, plastic or fiber-reinforced composite material, provided each of the plates provide structural stiffness and support. In at least one embodiment, the mounting and base plates416,418may be fabricated from an injection molded plastic. While the mounting and base plates416,418are depicted as separate elements to facilitate assembly, it will be appreciated that the plates416,418may be integrated. For example, the mounting plate416may directly mount to the shock tube422, thereby eliminating the requirement for a separate base plate418.

InFIGS. 6-7, the first end424of the shock tube422seals to the base plate418and defines the compression cavity446, when disposed in combination with the reciprocating piston410. The second end426of the shock tube422is open to receive at least a portion of the reciprocating piston410. Furthermore, the shock tube422includes a wall structure434defining a constant cross-section internal surface436for slideably engaging the reciprocating piston410. The damping orifice430may extend through the wall structure434proximal the first end424of the shock tube422, i.e., near the base plate418, and fluidically connects the accumulator and compression cavities442,446. While several orifices430are illustrated in this embodiment, it is contemplated that a single orifice430may be employed depending upon the desired amount of load damping. Furthermore, while the damping orifice430is shown extending through the wall structure434of the shock tube422, it will be appreciated that the orifice430may be axially disposed through the piston410provided that: (i) the valve mechanism414closes in response to a compressive stroke acting on the compression cavity, (ii) opens in response to a stroke separating the reciprocating piston410and the stationary piston guide, and (iii) fluidically connects the accumulator and compression cavities442,446of the shock absorbing apparatus400.

The reciprocating piston410: (i) sits in the open second end426of the shock tube422, (ii) connects to the underside of the impact plate420and (iii) reciprocates relative to the shock tube422in response to displacement of the impact plate420. In the illustrated embodiment, the piston410is shown as being integrated with the impact plate420, though, it should be appreciated that the reciprocating piston410may be connected to the impact plate420by a separate linkage, or other axial input member (not shown). In the described embodiment, the reciprocating piston410may include a piston ring454between the periphery of the piston410and the wall surface of the shock tube422.

InFIGS. 6 and 7, the valve mechanism414includes a check valve456disposed in the flow path provided by the conduit408. More specifically, the check valve456inhibits the flow of the viscous fluid450from the compression to the accumulator cavities446,442when a first pressure differential develops in the compression cavity446. Furthermore, the check valve456facilitates the flow of the viscous fluid450from the accumulator to the compression cavities442,446when a second pressure differential develops in the compression cavity446relative to the accumulator cavity442. The first pressure differential developed between the accumulator and compression cavities442,446is characterized by a higher pressure in the compression cavity446such that fluid flows from the compression cavity446, through the damping orifice430, to the accumulator cavity442. The valve mechanism414inhibits flow through the conduit408when the first pressure differential is developed. The second pressure differential is directionally reversed from the first pressure differential and is characterized by a higher pressure in the accumulator cavity442such that fluid flows from the accumulator cavity442, through the conduit408, to the compression cavity446. The valve mechanism414facilitates flow through the conduit408when the second pressure differential is developed. Additionally, flow through the conduit408may be augmented by a secondary flow, albeit at a far lower flow rate, through the damping orifice430. In the described embodiment, the valve mechanism414is disposed in combination with the reciprocating piston410, though any of a variety of flow paths may be created between the cavities442,446to prevent and facilitate flow therebetween.

In another embodiment depicted inFIG. 8, the stationary guide412comprises a piston guide or strut470mounting to, and projecting orthogonally from, the base plate418and an external reciprocating piston474. Furthermore, the piston guide or strut470is aligned with the impact shock load S acting on the impact plate420. In the described embodiment, the strut470is tubular, i.e., having a constant, external, cross-sectional shape along its length, and is cylindrical. Notwithstanding the illustrated embodiment, the piston guide470may have any of a variety of cross-sectional shapes including rectangular, square, triangular, hexagonal, or elliptical, etc. The only requirement is that the reciprocating piston474slide freely over the external surface of the piston guide470.

The first pressure differential is developed by a combination of: (i) the relative axial movement between the external piston474and the underlying strut470, and (ii) a tapered pin480projecting upwardly from the strut470into a selectively-shaped internal chamber484of the compression cavity446. With respect to the latter, the tapered pin480augments the change in volume within the compression cavity446as the piston474reciprocates axially on the external guide surface478of the strut470.

Similar to the previous embodiments, a check valve490is disposed in the flow path provided by the conduit408. More specifically, the check valve490: (i) inhibits the flow of the viscous fluid450from the compression to the accumulator cavities446,442when first pressure differential develops in the compression cavity446, and (ii) facilitates the flow of the viscous fluid450from the accumulator to the compression cavities446,442when a second pressure differential develops in the compression cavity446relative to the accumulator cavity442. In the described embodiment, the valve mechanism414is disposed in combination with the piston strut470, although one may contemplate any of a variety of flow paths, including flow paths through the reciprocating piston474to prevent and facilitate flow between the accumulator and compression cavities442,446.

In operation, and referringFIG. 9, the shock absorbing apparatus400can be disposed between die portions of a blow molding apparatus (not shown). As attached, the impact plate420is aligned in relation to a movable die portion (not shown) of the molding apparatus. As the die is closed, it engages the impact plate420as depicted by arrow S, generating a compressive load against the flexible elastomeric membrane404. The compressive impact load S causes an inward deformation of the elastomeric membrane404toward the mounting plate416.

The deformation of the flexible elastomeric membrane404and motion of the impact plate420displaces the compression assembly406, i.e., the reciprocating piston410within the stationary guide412. The motion of the reciprocating piston410causes the check valve456to close thereby preventing the reverse or back-flow of viscous fluid450from the compression cavity446into the accumulator cavity442via the conduit408. Rather, the displacement of the piston410forces the contained hydraulic fluid450through the damping orifice430. The shearing of the contained hydraulic fluid450through the damping orifice430, and the flexure of the elastomeric flexible membrane404act to convert the energy of the applied impact load S into heat which is, in turn, dissipated into the environment.

At the same time, the flow of the viscous fluid450from the compression cavity446to the accumulator cavity442builds pressure therein in the direction of the arrows P. The flexible membrane404bows outwardly (exaggerated as dashed lines to show the expansion of the membrane404) under the compression developed as the first pressure differential develops in the compression assembly406. As such, at least a portion of the kinetic energy is stored as potential energy in the stressed elastomeric material. The build-up of pressure from the compression assembly406may be viewed as analogous to the expansion of an internally pressurized balloon.

At the bottom of the piston stroke, the impact load ceases and the pressure differential reverses direction, i.e., the pressure developed in the accumulator cavity442exceeds the pressure in the compression cavity446. This reversal causes the viscous fluid450to flow through the conduit408from the accumulator to the compression cavities446,442. That is, the check valve456opens to allow flow to travel in the opposite direction. As mentioned earlier, fluid flow may be augmented by flow through the damping orifice430, though, to a far lesser extent. As a consequence, the hydraulic fluid450is restored to the compression cavity446and the shock absorber apparatus400is prepared/readied for another work cycle.

Inasmuch as the entire compression assembly406is disposed within the accumulator cavity442, all moving parts and sliding surfaces of the compression assembly406, including valves, sliding seals, etc., are contained within the one of the fluid cavities442,446. Consequently, the requirement for costly high tolerance, dynamic seals are eliminated. Furthermore, inasmuch as the flexible membrane404also functions in the capacity of an energy storage device, the requirement for energy storing springs, or other energy converting devices may be eliminated.

While this disclosure has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the present disclosure as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the invention, as required by the following claims. The claims provide the scope of the coverage of the invention and should not be limited to the specific examples provided herein.

It will be readily apparent that other variations and modifications can be understood from the discussion of the inventive concepts that have been discussed herein, including the appended claims.