Actuator with multi-function cap

Abstract

An actuator includes a housing having an inner surface and a proximal end. A gas generator is coupled to the proximal end. The actuator also includes a piston rod slidably engaged with the inner surface, the piston rod having a proximal end disposed adjacent the gas generator and a distal end opposite the proximal end. A cap is coupled to the proximal end of the piston rod, the cap having a seal portion and a dampening portion. The piston rod further has a shoulder disposed adjacent the proximal end of the piston rod, the shoulder having a first axial side facing the proximal end of the piston rod and a second axial side facing the distal end. The seal portion of the cap is disposed adjacent the first axial side of the shoulder and the dampening portion of the cap is disposed adjacent the second axial side of the shoulder.

Description

ACTUATOR WITH MULTI-FUNCTION CAPCross-Reference To Related Applications

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 664,895 filed on June 27, 2024, the entire contents of which are incorporated herein by reference.Technical Field

[0002] The present disclosure relates to safety devices for passenger vehicles. In particular, the disclosure relates to an actuator with a multi-function cap. Passenger vehicles may include, for example, automobiles, boats, trains, aircrafts, and spacecrafts.Background

[0003] Actuators in vehicles are capable of moving vehicle components and therefore have many potential uses, including for safety. In one example, an actuator can be used to lift a portion of a hood of an automobile (e.g., a rear portion of the hood proximate the windshield) in a situation during which the vehicle collides with a pedestrian. When actuated, the actuator raises the hood portion from its normal rest position to an elevated position to increase the space between the hood and rigid structures beneath the hood (e.g., an engine). When a pedestrian impacts the elevated hood, the extra space helps to "cushion" the pedestrian, lowering the likelihood of injury from impacting the rigid structures beneath the hood.

[0004] Prior to final installation in a vehicle, some actuator components may exit the actuator as a projectile if the actuator deploys at unexpected times due to uncontrolled factors. One example is during a fire while transporting the actuator between manufacturing facilities prior to final assembly in a vehicle, which can happen if a transporting vehicle gets into an accident. As a result, it is best to design the actuator such that energy from deployment can be managed appropriately when an unexpected deployment occurs. Often times, this requires additional components and increased cost.Therefore, there is a continuing need for maximizing functionality of actuators while minimizing the number of components to ensure increased adoption by vehicle manufacturers.Summary

[0005] in various implementations, an actuator comprises a housing comprising an inner surface, a central axis, a proximal end, and a distal end. A gas generator is coupled to the proximal end of the housing. A piston rod is slidably engaged with the inner surface of the housing, the piston rod comprising a proximal end disposed adjacent the gas generator when the piston rod is in a retracted position and a distal end disposed adjacent the distal end of the housing when the piston rod is in the retracted position. A cap is coupled to the proximal end of the piston rod, the cap comprising a seal portion and a dampening portion integrally formed together. The piston rod further comprises a central axis and a shoulder disposed adjacent the proximal end of the piston rod and extending in a plane perpendicular to the central axis of the piston rod, the shoulder comprising a first axial side facing the proximal end of the piston rod and a second axial side facing the distal end of the piston rod. The seal portion of the cap is disposed adjacent the first axial side of the shoulder and the dampening portion of the cap is disposed adjacent the second axial side of the shoulder.

[0006] In some implementations, the cap comprises a material having a melting point of 200 degrees C or less. In some implementations, the cap comprises acrylonitrile butadiene styrene (ABS). In other implementations, the cap comprises nylon. In other implementations, the cap comprises polyester.

[0007] In some implementations, the seal portion of the cap forms a seal with the inner surface of the housing to prevent fluid communication between the first axial side of the shoulder and the second axial side of the shoulder.

[0008] In some implementations, the distal end of the housing defines a distal end wall extending at least partially radially inwardly toward the central axis of the housing. In some implementations, the dampening portion of the cap impacts the distal end wall andcompresses to absorb energy when the piston rod moves from the retracted position to an extended position.

[0009] in some implementations, the dampening portion of the cap biases the central axis of the piston rod toward axial alignment with the central axis of the housing.

[0010] In some implementations, the cap defines an insertion cavity, wherein the proximal end of the piston rod is disposed within the insertion cavity.

[0011] In some implementations, the cap defines an ignition cavity and a ledge surrounding the ignition cavity, wherein the gas generator abuts the ledge when the piston rod is in the retracted position such that an outlet of the gas generator is disposed adjacent the ignition cavity.

[0012] In some implementations, the seal portion defines a weakened portion.

[0013] In some implementations, the dampening portion comprises two tabs. In some implementations, the two tabs are disposed 180 degrees apart from each other along a circumference of the cap.

[0014] In some implementations, the dampening portion comprises a plurality of tabs. In some implementations, the tabs of the plurality of tabs are equally spaced apart from each other along a circumference of the cap. In some implementations, the tabs of the plurality of tabs define an accordion shape. In some implementations, the tabs of the plurality of tabs form a snap-fit connection to the shoulder of the piston rod.

[0015] In some implementations, the shoulder comprises a non-circular shape when viewed along the central axis of the piston rod. In other implementations, the shoulder comprises a circular shape when viewed along the central axis of the piston rod.Brief Description of the Drawings

[0016] The drawings are merely exemplary to illustrate steps, structure, and certain features that can be used singularly or in combination with other features. The disclosure should not be limited to the implementations shown. Similar reference numerals (e.g., 101, 201, etc.) represent similar steps, structures, and features throughout the implementations shown.

[0017] FIG. 1 is a perspective view of an actuator in a retracted position.

[0018] FIG. 2 is a cross-sectional view of the actuator of FIG. 1 taken along the plane A-A in FIG. 1 comprising a first implementation of a cap.

[0019] FIG. 3 is a cross-sectional view of a portion of the actuator of FIG. 2.

[0020] FIG. 4 is a perspective view of a piston rod of the actuator of FIG. 2.

[0021] FIG. 5 is another perspective view of the piston rod of FIG. 4.

[0022] FIGS. 6A-6B are perspective views of the cap of FIG. 2.

[0023] FIG. 7 is a cross-sectional view of the actuator of FIG. 2 in an extended position.

[0024] FIG. 8 is a cross-sectional view of the actuator of FIG. 1 taken along the plane A-A in FIG. 1 comprising a second implementation of a cap.

[0025] FIGS. 9A-9B are perspective views of the cap of FIG. 8.

[0026] FIG. 10 is a cross-sectional view of the actuator of FIG. 1 taken along the plane A-A in FIG. 1 comprising a third implementation of a cap.

[0027] FIG. 11 is a cross-sectional view of the actuator of FIG. 10 in an extended position.

[0028] FIG. 12 is a perspective view of a piston rod of the actuator of FIG. 10.

[0029] FIG. 13 is a perspective view of the cap of FIG. 10.

[0030] FIG. 14 is a perspective view of the cap of FIG. 10 having an alternative design.

[0031] FIG. 15 is a perspective view of a fourth implementation of a cap.

[0032] FIG. 16 is a perspective view of a fifth implementation of a cap.Detailed Description

[0033] The devices, systems, and methods disclosed herein provide for an actuator having a multi-function cap. The actuator can be included in a hood lifting mechanism for lifting the hood of a vehicle, for example. The actuator includes a housing and a piston rod slidably engaged with an inner surface of the housing, wherein the piston rod comprises a proximal end and a distal end. A cap is coupled to the proximal end of the piston rod to provide a seal between the piston rod and the inner surface of the housing. Additionally, the cap provides for an energy dampening feature when the piston rod moves from a retracted position to an extended position. As used herein, the verb "seal" (and correlative nouns, adjectives, etc.) means to limit, including fully prevent, fluid communication between two or more locations, structures, surfaces, components, etc., as well as to limit, including fullyprevent, the movement of solid material (e.g., dirt or dust) between two or more locations, structures, surfaces, components, etc.

[0034] Referring to the FIGS. 1-7, an actuator 100 comprises a housing 101 comprising a proximal end 102, a distal end 103, and a wall 106 extending from the proximal end 102 to the distal end 103. The wail 106 comprises an inner surface 107 and an outer surface 108. The housing 101 further comprises a central axis 109 extending through the proximal end 102 and the distal end 103. The distal end 103 defines a distal end wall 104 extending at least partially radially inward toward the central axis 109. An opening 105 is defined by the distal end wall 104 and is configured for allowing a piston rod 116 to extend from the housing 101, as described below. An inner volume 110 is defined within the housing 101, bounded by the inner surface 107, the proximal end 102, and the distal end 103. In some implementations, the housing 101 may be formed from metal, such as stainless steel, and may be formed by a deep drawing process.

[0035] The piston rod 116 comprises a proximal end 117 and a distal end 118 opposite the proximal end 117. In a retracted position, as shown in FIG. 2, the distal end 118 of the piston rod 116 is adjacent the distal end 103 of the housing 101 and the piston rod 116 is substantially disposed within the inner volume 110 of the housing 101. In an extended position, as shown in FIG. 7 as an isolated view of the housing 101, the piston rod 116, and a cap 124 (discussed below), the proximal end 117 of the piston rod 116 is adjacent the distal end 103 of the housing 101 and the piston rod 116 is substantially disposed outside the inner volume 110 of the housing 101. The piston rod 116 may take the form of a solid rod, as shown in FIG. 2. In some implementations, the piston rod 116 may be formed from metal, such as stainless steel, and be formed by a deep drawing process.

[0036] To deploy the actuator 100 and therefore move the piston rod 116 from the retracted position to the extended position, a gas generator 111 is coupled to the proximal end 102 of the housing 101. The gas generator 111 may be coupled to a vehicle electronic control unit (ECU, not shown) via a lead wire 112 to form an electrical connection between the gas generator 111 and the ECU. In some implementations, the gas generator 111 may be a pyrotechnic gas generator, such as an initiator or micro gas generator, both well known in the art. In other implementations, the gas generator may comprise a source of stored, pressurized gas that is released upon actuation.

[0037] When the ECU sends an actuation signal to the gas generator 111, the gas generator 111 introduces high-pressure gas into the inner volume 110 of the housing 101. The high- pressure gas will push against the proximal end 117 of the piston rod 116 thereby pushing the piston rod 116 from the retracted position to the extended position. The piston rod 116 further comprises a shoulder 120 disposed adjacent the proximal end 117 of the piston rod 116 and extending in a plane perpendicular to a central axis 119 of the piston rod 116. The shoulder 120 comprises a first axial side 121 facing the proximal end 117 of the piston rod 116 and a second axial side 122 facing the distal end 118 of the piston rod 116. The cap 124 is coupled to the proximal end 117 of the piston rod 116 around the shoulder 120 to prevent the high-pressure gas from passing around the shoulder 120 and between the piston rod 116 and the inner surface 107 of the housing 101.

[0038] The cap 124 comprises a seal portion 125 and a dampening portion 126 integrally formed together such that the cap 124 is a single component. When coupled to the proximal end 117 of the piston rod 116, the seal portion 125 is disposed adjacent the first axial side 121 of the shoulder 120 and the dampening portion 126 is disposed adjacent the second axial side 122 of the shoulder. A transition portion 127 extends between the seal portion 125 and the dampening portion 126 such that the transition portion 127 fills a space between the shoulder 120 and the inner surface 107 of the housing 101, as shown in FIG. 3 for example.

[0039] The cap 124 defines an insertion cavity 131 surrounded by a ledge 130. An insertion portion 123 disposed at the proximal end 117 of the piston rod 116 extends into the insertion cavity 131 when the piston rod 116 is coupled to the cap 124 such that the proximal end 117 is disposed within the insertion cavity 131. The first axial side 121 of the shoulder 120 abuts the ledge 130 when the insertion portion 123 is fully inserted into the insertion cavity 131. The cap 124 also defines an ignition cavity 129 and a ledge 128. The gas generator 111 abuts the ledge 128 when the piston rod 116 is in the retracted position such that an outlet of the gas generator 111 is disposed adjacent the ignition cavity 129. The ignition cavity 129 facilitates an opening of the outlet of the gas generator 111 and provides an initial space for the high-pressure gases from the gas generator 111 to exit and begin pushing against the piston rod 116.

[0040] The seal portion 125 of the cap 124 forms a seal with the inner surface 107 of the housing 101 to prevent fluid communication between the first axial side 121 of the shoulder120 and the second axial side 122 of the shoulder 120. The seal portion 125 represents the largest circumference of the cap 124 such that the seal portion 125 is in contact with the inner surface 107 of the housing 101 along its entire circumference. This allows the seal portion 125 to seal the space between the piston rod 116 and the housing 101, allowing for maximum efficiency during the movement of the piston rod 116 from the retracted position to the extended position after deploying the gas generator 111.

[0041] When the piston rod 116 moves from the retracted position to the extended position, the dampening portion 126 of the cap 124 will impact the distal end wall 104 of the housing 101 and compress to absorb energy. In this instance, "compress" includes similar terms such as "crush" or "crumple," i.e., any mechanism by which the dampening portion 126 can lose structural integrity when impacting the distal end wall 104. By absorbing energy at impact during normal operation, the cap 124 helps to prevent the piston rod 116 from fully exiting the inner volume 110 and therefore the housing 101. Additionally, during normal operation of the actuator 100, absorbing energy at the end of the movement of the piston rod 116 provides a braking effect to avoid excess damage to any component moved by the actuator 100, such as a vehicle hood bracket.

[0042] In some instances, the actuator 100 may come into thermal communication with an external heat source, such as a fire on a logistics vehicle during shipment, that heats the actuator 100 to a point where the gas generator 111 could auto-deploy. Since the actuator 100 is not installed in its final end use, such as under a vehicle hood, there may be no resistance to the piston rod 116 during deployment. As a result, the dampening portion 126 could be overpowered and the piston rod 116 could exit the housing 101 and become a projectile. To avoid this hazard, the actuator needs to be able to vent at least some of the high-pressure gases from the gas generator 111 to an external environment.

[0043] The cap 124 serves this additional purpose because it is capable of melting when the external heat source raises the temperature of the cap 124 to above a threshold temperature. Once this happens, the cap 124 will lose structural integrity and the seal will be broken, thus allowing any high-pressure gases from the gas generator 111 to pass between the piston rod 116 and the inner surface 107 of the housing 101 (e.g., around the shoulder 120). This high-pressure gas can then exit the housing 101 through the opening 105 in the distal end wall 104, thus reducing the power and speed with which the piston rod 116 will move from the retracted position to the extended position. The term "melting" isused to include melting as well as other losses of structural form, depending on the material chosen for the cap 124. For example, melting can also refer to correlative processes such as the glass- transition temperature for amorphous solids. Therefore, the threshold temperature is the temperature at which a chosen material will lose its structural integrity. The above-described event is one example of a "dry fire" event, wherein the actuator 100 is actuated without resistance from an external force.

[0044] To accomplish all of the above-described features of the cap 124, the cap 124 may comprise, in some implementations, a plastic material, such as acrylonitrile butadiene styrene (ABS) with a melting temperature of approximately 220 degrees Celsius, ensuring the cap 124 loses structural integrity before the gas generator 111 actuates in response to the external heat source while being able to produce a seal and compress during normal operation of the actuator 100, as previously described. In other implementations, the cap may comprise any other material capable of performing these functions, such as other inelastic polymer materials (e.g., nylon or polyester), plastics, or elastic materials (e.g., rubber). In some implementations, the cap may comprise a material having a melting point of 200 degrees of less.

[0045] The cap 124 is capable of yet another important function. For optimal performance of the actuator 100, the central axis 119 of the piston rod 116 and the central axis 109 of the housing 101 should be coaxial with each other. As best shown in FIGS. 6A-6B, the dampening portion 126 of the cap 124 comprises a plurality of tabs 132. The tabs 132 of the plurality of tabs 132 are equally spaced apart from each other along the circumference of the cap 124. To couple the cap 124 to the piston rod 116, the proximal end 117 of the piston rod 116, including the shoulder 120 and insertion portion 123, is inserted through the tabs 132 such that the tabs 132 bend away from and then snap back over the shoulder 120 to form a snap-fit connection. As shown in FIG. 2, the tabs 132 abut the piston rod 116 around its entire circumference and therefore the dampening portion 126 biases the central axis 119 of the piston rod 116 toward axial alignment with the central axis 109 of the housing 101 (only central axis 109 is shown in FIG. 2 as it is the same as central axis 119 when the two are in axial alignment).

[0046] As shown in FIGS. 8-9B, a second implementation of a cap 224 is similar to the cap 124. The cap 224 comprises a seal portion 225, a dampening portion 226 comprising tabs 232, and a transition portion 227. However, the cap 224 includes an additional sealingmechanism. Cap 224 defines a groove 234 in which a seal 233 is disposed, such as a rubber o-ring, for example. The seal 233 can further bolster the sealing affect of the cap 224, if necessary, in certain implementations of the actuator 100 by providing another seal between the inner surface 107 of the housing 101 and the cap 224. Additionally, the insertion cavity 231 and the ignition cavity 229 (surrounded by ledges 230 and 228, respectively) may comprise one through-hole extending through the cap 224. As shown in FIG. 8, the insertion portion 123 of the piston rod 116 may extend only partially through the through-hole such that the ignition cavity 229 remains for the same purposes as described above.

[0047] In the implementations shown in FIGS. 1-9B, the shoulder 120 of the piston rod 116 comprises a circular shape when viewed along the central axis 119 of the piston rod 116, as clearly shown in FIG. 4. In FIGS. 10-14, the actuator 100 comprises a third implementation of a cap 324 which uses a piston rod 316 with a shoulder 320 that comprises a non-circular shape when viewed along the central axis 319 of the piston rod 316, as clearly shown in FIG.12. The shoulder 320 comprises two straight sides and two rounded sides. As shown in FIG.13, the cap 324 comprises a dampening portion 326 comprising a plurality of tabs 332 (e.g., 10) in opposing positions along the circumference of the cap 324 which snap over the straight sides of the shoulder 320. As shown in FIG. 14, the cap 324 comprises a different plurality of tabs 332 (e.g., 4).

[0048] As shown in FIG. 10, the dampening portion 326, i.e., the tabs 332, abuts the piston rod 316 adjacent the second axial side 322 of the shoulder 320 to facilitate axial alignment of the central axis 109 of the housing 101 and the central axis 319 of the piston rod 316, similar to the description above. The cap 324 may also comprise an extension 335 extending from the seal portion 325. A weakened portion comprising a tear seam 336 may be present between the seal portion 325 and the extension 335 to facilitate breaking apart of the seal portion 325 and the extension 335. This may be necessary in some cases if the gas generator 111 over-pressurizes internally and expands radially outward. In this case, the cap 324 can separate from the extension 335 and still operate nominally as the piston rod 316 moves from the retracted position to the extended position.

[0049] As shown in FIG. 11, the actuator 100 is in the extended position and the proximal end 317 of the piston rod 316 is adjacent the distal end 103 of the housing 101 and the piston rod 316 is substantially disposed outside the inner volume 110 of the housing 101.The dampening portion 326 of the cap 324 abuts the distal end wall 104 of the housing 101 and is compressed, as described above with respect to cap 124. As a result, the cap 324 absorbs energy from the movement of the piston rod 316 and prevents the piston rod 316 from fully exiting the housing 101, as described above.

[0050] Referring now to FIG. 15, a fourth implementation of a cap 424 is shown. The cap 424 comprises a seal portion 425, a dampening portion 426, a transition portion 427, an extension 435, an insertion cavity 431, and a ledge 430. The cap 424 is similar to the cap 324 however the dampening portion 426 comprises a plurality of tabs 432 that comprises two tabs 432. The two tabs 432 are disposed 180 degrees apart from each other along a circumference of the cap 424. Additionally, the tabs 432 define an accordion shape. The accordion shape facilitates the compression of the dampening portion 426 when the actuator 100 moves from the retracted position to the extended position.

[0051] Referring now to FIG. 16, a fifth implementation of a cap 524 is shown. The cap 524 comprises a seal portion 525, a dampening portion 526, a transition portion 527, an insertion cavity 531, and a ledge 530. The cap 524, similar to the cap 424 described above, comprises a dampening portion 526 that comprises two tabs 532 spaced 180 degrees apart from each other along a circumference of the cap 524. Here, however, the tabs 532 are shorter and lack the accordion shape of tabs 432 of the cap 424.

[0052] Finally, as shown in FIGS. 1-2 and 11, the actuator 100 may include a first mounting bracket 114 and a second mounting bracket 115 coupled to the distal end 103 of the housing 101. The mounting brackets 114 / 115 facilitate mounting the actuator 100 to a vehicle, for example, and allow for routing the lead wire 112 through to the ECU. A striker 11.3 may be coupled to the second mounting bracket 115. The striker 113 may comprise an elastic or inelastic material, for example rubber or plastic, to limit the noise associated with vehicle vibrations, for example, when the actuator 100 is installed in a vehicle. As shown in FIG. 11, the piston rod 316 may break open the striker 113 and extend through the striker 113 as the piston rod 316 moves from the retracted position to the extended position.

[0053] The description in the present disclosure has been presented for purposes of illustration but is not intended to be exhaustive or limited to the implementations disclosed. It will be understood that various modifications and variations will be apparent to those of ordinary skill in the art and may be made without departing from the spirit and scope of the following claims. Accordingly, other implementations are within the scope of the claims.The implementations described were chosen in order to best explain the principles of the actuator and its practical application, and to enable others of ordinary skill in the art to understand the assembly for various implementations with various modifications as are suited to the particular use contemplated.

[0054] The terms "coupled," "connected," and the like as used herein to mean the joining of two members directly or indirectly to one another. Such joining may be stationary (e.g., permanent) or moveable (e.g., removable or releasable). Such joining may be achieved with the two members or the two members and any additional intermediate members being integrally formed as a single unitary body with one another or with the two members or the two members and any additional intermediate members being attached to one another.

[0055] The terminology used herein is for the purpose of describing particular implementations only and is not intended to be limiting of the disclosure. As used herein, the singular forms “a,” “an,” and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises” and / or "comprising,” when used in this specification, specify the presence of stated features, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, operations, elements, components, and / or groups thereof.

Claims

CLAIMSWhat is claimed is:

1. An actuator comprising: a housing comprising an inner surface, a central axis, a proximal end, and a distal end; a gas generator coupled to the proximal end of the housing; a piston rod slidably engaged with the inner surface of the housing, the piston rod defining a central axis and comprising a proximal end disposed adjacent the gas generator when the piston rod is in a retracted position, a distal end disposed adjacent the distal end of the housing when the piston rod is in the retracted position, and a shoulder disposed adjacent the proximal end of the piston rod and extending in a plane perpendicular to the central axis of the piston rod, the shoulder comprising a first axial side facing the proximal end of the piston rod, and a second axial side facing the distal end of the piston rod; and a cap coupled to the proximal end of the piston rod, the cap comprising a seal portion disposed adjacent the first axial side of the shoulder, and a dampening portion integrally formed together with the seal portion and disposed adjacent the second axial side of the shoulder.

2. The actuator of claim 1, wherein the cap comprises a material having a melting point of 200 degrees C or less.

3. The actuator of claim 2, wherein the cap comprises acrylonitrile butadiene styrene (ABS).

4. The actuator of claim 2, wherein the cap comprises nylon.

5. The actuator of claim 2, wherein the cap comprises polyester.

6. The actuator of claim 1, wherein the seal portion of the cap forms a seal with the inner surface of the housing to inhibit fluid communication between the first axial side of the shoulder and the second axial side of the shoulder.

7. The actuator of claim 1, wherein the distal end of the housing defines a distal end wall extending at least partially radially inwardly toward the central axis of the housing.

8. The actuator of claim 7, wherein the dampening portion of the cap impacts the distal end 'wall and compresses to absorb energy when the piston rod moves from the retracted position to an extended position.

9. The actuator of claim 1, wherein the dampening portion of the cap biases the central axis of the piston rod toward axial alignment with the central axis of the housing.

10. The actuator of claim 1, wherein the cap defines an insertion cavity, wherein the proximal end of the piston rod is disposed within the insertion cavity.

11. The actuator of claim 1, wherein the cap defines an ignition cavity and a ledge surrounding the ignition cavity, wherein the gas generator abuts the ledge when the piston rod is in the retracted position such that an outlet of the gas generator is disposed adjacent the ignition cavity.

12. The actuator of claim 1, wherein the seal portion defines a weakened portion.

13. The actuator of claim 1, wherein the dampening portion comprises two tabs.

14. The actuator of claim 13, wherein the two tabs are disposed 180 degrees apart from each other along a circumference of the cap.

15. The actuator of claim 1, wherein the dampening portion comprises a plurality of tabs.

16. The actuator of claim 15, wherein the tabs of the plurality of tabs are equally spaced apart from each other along a circumference of the cap.

17. The actuator of claim 15, wherein the tabs of the plurality of tabs define an accordion shape.

18. The actuator of claim 15, wherein the tabs of the plurality of tabs form a snap-fit connection to the shoulder of the piston rod.

19. The actuator of claim 18, wherein the shoulder comprises a non-circular shape when viewed along the central axis of the piston rod.

20. The actuator of claim 18, wherein the shoulder comprises a circular shape when viewed along the central axis of the piston rod.

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