Actuator with cap

Abstract

An actuator includes a housing having a central axis, an inner surface, a distal end, and a proximal end. The distal end defines a distal end wall that extends at least partially radially inwardly toward the central axis. A gas generator is coupled to the proximal end. The actuator also includes a piston rod slidably engaged with the inner surface of the housing, the piston rod having a proximal end disposed adjacent the gas generator and a distal end disposed adjacent the distal end of the housing..A cap is coupled to the distal end of the piston rod, the cap defining a cavity having a first portion, a second portion, and an end wall. The first portion has a first wall and the second portion has a second wall, and the second wall tapers toward the central axis from adjacent the first wall toward the end wall.

Description

Client Docket No.: P-2-00535 WO1 Attorney Docket No.: 10213-294WO1 ACTUATOR WITH CAP CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 653,362 filed on May 30, 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 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 the 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] Unfortunately, the area under the hood in a vehicle, where the actuator is typically installed, is not sealed from the environment and is susceptible to moisture, dirt, mud, and other contaminants depending on weather and road conditions. As a result, any actuator installed under the hood needs to be effectively sealed against these and other contaminants in order to ensure long term functionality and optimum performance. Due to the nature of actuators including extending piston rods, sealing the actuator can be difficult. Therefore, there is a continuing need for improved sealing with respect to vehicle actuators, such that long-term, consistent performance can be achieved. ^Client Docket No.: P-2-00535 WO1 Attorney Docket No.: 10213-294WO1 SUMMARY

[0005] In various implementations, an actuator comprises a housing comprising a central axis, an inner surface, a distal end, and a proximal end, the distal end defining a distal end wall extending at least partially radially inwardly toward the central axis. 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 distal end of the piston rod, the cap defining a cavity comprising a first portion, a second portion, and an end wall. The first portion comprises a first wall and the second portion comprises a second wall, wherein the second wall tapers toward the central axis from adjacent the first wall toward the end wall.

[0006] In some implementations, the cap comprises a cover portion and a dampening portion. In some implementations, the cover portion is disposed outside of the housing when the piston rod is in the retracted position. In some implementations, the dampening portion is disposed within the housing when the piston rod is in the retracted position. In some implementations, the cap further defines a groove between the cover portion and the dampening portion, wherein the distal end wall is disposed within the groove when the piston rod is in the retracted position.

[0007] In some implementations, the first portion of the cavity comprises a rectangular cross section as taken through a plane parallel to the central axis. In some implementations, the second portion of the cavity comprises a substantially trapezoidal cross section as taken through the plane parallel to the central axis. In some implementations, the cap further comprises a transition portion, wherein the transition portion is disposed between the first portion and the second portion. In some implementations, the transition portion comprises a third wall, wherein the third wall extends from the first wall to the second wall. In some implementations, the transition portion comprises a trapezoidal cross section as taken through the plane parallel to the central axis.

[0008] In some implementations, the piston rod is movable from the retracted position to an extended position upon actuation of the gas generator. In some implementations, the cover portion defines a weakened portion, wherein the piston rod breaks the weakened portion and ^Client Docket No.: P-2-00535 WO1 Attorney Docket No.: 10213-294WO1 extends through the cover portion as the piston rod moves from the retracted position to the extended position.

[0009] In other implementations, the cover portion defines a weakened portion, wherein the piston rod breaks the weakened portion and separates the cover portion from the dampening portion as the piston rod moves from the retracted position to the extended position. In some implementations, the end wall of the cap is permanently coupled to the distal end of the piston rod by an adhesive.

[0010] In some implementations, the housing further comprises an outer surface, wherein the housing defines gas relief openings extending from the inner surface to the outer surface. In some implementations, the actuator further comprises a sleeve, the sleeve covering the gas relief openings. In some implementations, the sleeve comprises acrylonitrile butadiene styrene (ABS). In some implementations, the sleeve defines a shoulder, wherein the proximal end of the piston rod abuts the shoulder when the piston rod is in the retracted position.

[0011] In some implementations, the cap comprises an elastic material. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] 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.

[0013] FIG.1 is a perspective view of an actuator having a cap.

[0014] FIG.2 is a cross-sectional view of the actuator of FIG.1 as taken along the plane A-A in FIG.1.

[0015] FIG.3 is a cross-sectional view of a portion of the actuator of FIG.2.

[0016] FIG.4 is a cross-sectional view of a different portion of the actuator of FIG. 2.

[0017] FIG.5 is a perspective view of the cap of FIG.1.

[0018] FIG.6 a cross-sectional view of the cap of FIG.5 as taken along the plane B-B in FIG. 5. ^Client Docket No.: P-2-00535 WO1 Attorney Docket No.: 10213-294WO1

[0019] FIG.7 is another perspective view of the cap of FIG.5.

[0020] FIG. 8 is a cross-sectional view of a portion of the actuator of FIG. 2 showing an isolated view of a piston rod coupled to the cap prior to final installation into a housing.

[0021] FIG. 9 is a cross-sectional view of the piston rod and cap of FIG. 8 installed into the housing.

[0022] FIGS.10A-10B are cross-sectional views of a portion of the actuator of FIG.2 wherein the cap comprises a weakened portion allowing a cover portion of the cap to separate from the cap.

[0023] FIGS.11A-11B are cross-sectional views of a portion of the actuator of FIG.2 wherein the cap comprises a weakened portion allowing the piston rod to push through the cap. DETAILED DESCRIPTION

[0024] The devices, systems, and methods disclosed herein provide for an actuator having a 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 distal end of the piston rod to provide a seal between the piston rod and the housing when the piston rod is in a retracted position. As used herein, the verb “seal” means to limit, including fully prevent, fluid communication between two or more locations, structures, surfaces, components, etc., as well as to limit, including fully prevent, the movement of solid material (e.g., dirt or dust) between two or more locations, structures, surfaces, components, etc.

[0025] Referring to the FIGS. 1-4, 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 wall 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 from the inner surface 107. An opening 105 is defined by the distal end wall 104 and is configured for allowing a piston rod 116 to extend ^Client Docket No.: P-2-00535 WO1 Attorney Docket No.: 10213-294WO1 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.

[0026] The piston rod 116 comprises a piston head 119 adjacent 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, 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. A seal 120, such as a rubber o-ring, may be disposed around the piston head 119, wherein the piston head 119 and seal 120 may be sized such that they are slidably engaged with the inner surface 107 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.

[0027] To deploy the actuator 100 and therefore move the piston rod 116 from the retracted position to the extended position, a gas generator 113 is coupled to the proximal end 102 of the housing 101. The gas generator 113 may be coupled to a vehicle electronic control unit (ECU, not shown) to form an electrical connection between the gas generator 113 and the ECU. In some implementations, the gas generator 113 may be a pyrotechnic gas generator, such as an initiator or micro gas generator. In some implementations, the gas generator may comprise a source of stored, pressurized gas that is released upon actuation.

[0028] When the ECU sends an actuation signal to the gas generator 113, the gas generator 113 introduces high-pressure gas into the inner volume 110 of the housing 101. The seal 120 inhibits the high-pressure gas from passing around the piston head 119 and between the piston rod 116 and the inner surface 107 of the housing 101. The high-pressure gas will therefore 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.

[0029] As shown in FIGS. 2 and 4, the actuator 100 may further comprise a sleeve 114 disposed within the inner volume 110 of the housing 101 adjacent the proximal end 102 of the housing 101 and around the gas generator 113. The sleeve 114 covers gas relief openings 111 ^Client Docket No.: P-2-00535 WO1 Attorney Docket No.: 10213-294WO1 formed in the housing 101 extending from the inner surface 107 to the outer surface 108, inhibiting fluid communication between the inner volume 110 of the housing 101 and the outside environment during normal operation of the actuator 100. The sleeve 114 defines a shoulder 115 adjacent to the proximal end 117 of the piston rod 116 in the retracted position. In some implementations, the proximal end 117 abuts the shoulder 115 in the retracted position. The shoulder 115 defines an opening to allow high-pressure gas from the gas generator 113 to push against the distal end 117 of the piston rod 116.

[0030] In the event the actuator 100 is in communication with an external heat source, such as a fire that heats the actuator 100 and causes the sleeve 114 to be heated above a threshold temperature, the sleeve 114 melts, allowing fluid communication between the outside environment and the inner volume 110 of the housing 101 through the gas relief openings 111. The threshold temperature is defined as the melting temperature of the sleeve 114. Therefore, in the event the gas generator 113 actuates in response to the external heat source after the sleeve 114 melts, high-pressure gases from the gas generator 113 will flow to the outside environment through the gas relief openings 111, reducing the pressure on the proximal end 117 of the piston rod 116. This event is one example of a “dry fire” event, wherein the actuator 100 is actuated without resistance from an external force, such as the hood of the vehicle.

[0031] During a dry fire event, there is a risk that the piston rod 116 may be driven with too much energy and could fully exit the housing 101. Therefore, reducing the pressure by venting the high-pressure gas to the outside environment reduces this risk. In some implementations, the sleeve 114 may comprise a plastic material, for example acrylonitrile butadiene styrene (ABS) with a melting temperature of approximately 220 degrees Celsius, ensuring the sleeve 114 decomposes before the gas generator 113 actuates in response to the external heat source. In other implementations, the sleeve 114 may be made from any other material capable of melting before the gas generator 113 actuates automatically in response to the external heat source, such as other plastic materials and certain metals. In some implementations, a seal tape 112 surrounds the outer surface 108 of the housing 101 and cover the gas relief openings 111, further sealing them from the outside environment during normal operation while being capable of melting during a dry fire event to allow fluid communication between the outside environment and the inner volume 110 of the housing 101.

[0032] Referring now to FIGS. 1-3 and 5-9, a cap 121 is coupled to the distal end 118 of the piston rod 116. The cap 121 comprises a cover portion 122 and a dampener portion 124. The ^Client Docket No.: P-2-00535 WO1 Attorney Docket No.: 10213-294WO1 cover portion 122 comprises a shoulder 125 and a groove 126 is defined between the shoulder 125 and the dampener portion 124. A portion of the distal end wall 104 is disposed within the groove 126 when the actuator 100 is fully assembled. As a result, the cover portion 122 is disposed outside of the inner volume 110 of the housing 101 while the dampener portion 124 is disposed within the inner volume 110 of the housing 101.

[0033] The cap 121 may be made from an elastic material, such as rubber, to enable the cap 121 to seal the inner volume 110 of the housing 101 from the outside environment, as further described below. Additionally, the elastic material allows the dampener portion 124 to absorb energy from the piston rod 116 as it moves from the retracted position to the extended position. When the piston rod 116 nears the end of its stroke, the piston head 119 will impact a retaining wall 135 of the dampener portion 124 and cause the dampener portion 124 to compress. Energy absorption in this way will ensure the piston rod 116 does not eject from the housing 101. This added feature of the cap 121 removes any necessity for a separate dampener component within the housing 101.

[0034] The cap 121 defines a cavity 127 extending from the retaining wall 135 to an end wall 134. The cavity 127 comprises a first portion 128, a second portion 130, and a transition portion 132 disposed between the first portion 128 and the second portion 130. The first portion comprises a first wall 129 and the second portion 130 comprises a second wall 131. The transition portion 130 comprises a third wall 133 which extends from the first wall 129 to the second wall 131.

[0035] As shown in FIG.6, the first portion 128 comprises a rectangular cross section as taken through a plane parallel to the central axis 109 (B-B as shown in FIG.5). In other words, when viewed as a cross section taken along the plane parallel to the central axis 109, the first portion 128 comprises a rectangular shape. The transition portion 132 comprises a trapezoidal cross section as taken through the plane parallel to the central axis 109. In other words, when viewed as a cross section taken along the plane parallel to the central axis 109, the transition portion 132 comprises a trapezoidal shape. The second portion 130 comprises a substantially trapezoidal cross section as taken through the plane parallel to the central axis 109. In other words, when viewed as a cross section taken along the plane parallel to the central axis 109, the second portion 130 comprises a substantially trapezoidal shape, as the second wall 131 may curve into the end wall 134 along a radius of curvature, as best shown in FIG.6. ^Client Docket No.: P-2-00535 WO1 Attorney Docket No.: 10213-294WO1

[0036] The second wall 131 tapers toward the central axis from adjacent the first wall 129 toward the end wall 134. As shown in FIG.8, the second wall tapers at an angle theta (^) with respect to a line parallel to the central axis 109 from the third wall 133 toward the end wall 134. In some implementations, the angle ^ can be 1 degree to 20 degrees. In one example, the angle ^ is approximately 5 degrees. In another example, the angle ^ is approximately 10 degrees.

[0037] To install the piston rod 116 and cap 121 into the actuator 100, the distal end 118 of the piston rod 116 is inserted into the first portion 128 of the cavity 127 up to the transition portion 132, as shown in FIG. 8. When inserted into the housing 101, the cap 121 will push through the opening 105 in the distal end wall 104 facilitated by a ramped surface 123, resulting in the distal end wall 104 being disposed within the groove 126. The dampening portion 124 is sized to inhibit the cap 121 from pushing further through the opening 105 by pushing against the end wall 104.

[0038] To finish installation of the piston rod 116 into the actuator 100, the piston rod 116 is pushed through the transition portion 132 and through the second portion 130 until the distal end 118 of the piston rod 116 reaches and abuts the end wall 134 of the cavity 127. The trapezoidal cross section of the transition portion 132 acts as a ramp to facilitate easier movement of the piston rod 116 from the first portion 128 to the second portion 130. As the piston rod 116 moves through the second portion 130, the tapered second wall 131 will be forced radially outward and partially axially toward the distal end wall 104 of the housing 101, as shown by the arrows in FIG.9. The cap 121 will therefore be compressed between the piston rod 116 and the distal end wall 104 of the housing 101, resulting in an effective, reliable seal between the piston rod 116 and the housing 101.

[0039] In some implementations, when the piston rod 116 moves from the retracted position to the extended position, the piston rod 116 may separate the cover portion 122 from the cap 121. As shown in FIGS.10A-10B, the cap 121 may comprise weakened portions 136, such as a thinned-out portion or groove, which allows the cover portion 122 to tear apart from the cap 121. The distal end 118 of the piston rod 116 may be permanently coupled to the end wall 134 of the cap 121, for example by an adhesive, such that the cover portion 122 will remain coupled to the distal end 118 of the piston rod 116 before, during, and after actuation of the actuator 100. ^Client Docket No.: P-2-00535 WO1 Attorney Docket No.: 10213-294WO1

[0040] In other implementations, when the piston rod 116 moves from the retracted position to the extended position, the piston rod 116 may break through the cover portion 122. As shown in FIGS. 11A-11B, the cap 121 may comprise a severance feature in the form of weakened portion 136 (e.g., a thinned-out portion, a groove, a parting line, a separation line, etc.) which allows the cover portion 122 to break open. The distal end 118 of the piston rod 116 may push through the weakened portion 136 of the cover portion 122, such that the cover portion 122 will remain coupled to the rest of the cap 121 as one integrally formed structure. As shown in FIGS. 10A and 10B, the cap 121 includes a weakened portion 136 in the form of an annular parting line that allows the cover portion 122 to completely separate from the cap 121 during actuation to the extended position. FIG. 10B shows the cover portion 122 removed from the cap 121 and maintained in contact with the distal end 118 of the piston rod 116. As shown in FIGS. 11A and 11B, the cap 121 includes a weakened portion 136 in the form of a point weakness, allowing the distal end 118 of the piston rod 116 to pierce through the cover portion 122. As shown in FIG.11B, the cover portion 122 remains connected to the cap 121 when the piston rod 116 is arranged in the extended position. In some implementations, the weakened portion 136 may include radial parting lines extending from a central point weakness, disconnected radial parting lines, concentric parting lines, or other severance features, as desired.

[0041] 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.

[0042] 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 ^Client Docket No.: P-2-00535 WO1 Attorney Docket No.: 10213-294WO1 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.

[0043] 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.

[0044] Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another aspect includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about”, it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. The terms “about” and “approximately” are defined as being “close to” as understood by one of ordinary skill in the art. In one non-limiting aspect the terms are defined to be within 10%. In another non-limiting aspect, the terms are defined to be within 5%. In still another non-limiting aspect, the terms are defined to be within 1%. ^

Claims

Client Docket No.: P-2-00535 WO1 Attorney Docket No.: 10213-294WO1 CLAIMS What is claimed is:

1. An actuator comprising: a housing comprising a central axis, an inner surface, a distal end, and a proximal end, the distal end defining a distal end wall extending at least partially radially inwardly toward the central axis; 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 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; and a cap coupled to the distal end of the piston rod, the cap defining a cavity comprising a first portion, a second portion, and an end wall; wherein the first portion comprises a first wall and the second portion comprises a second wall; wherein the second wall tapers toward the central axis from adjacent the first wall toward the end wall.

2. The actuator of claim 1, wherein the cap comprises a cover portion and a dampening portion.

3. The actuator of claim 2, wherein the cover portion is disposed outside of the housing when the piston rod is in the retracted position.

4. The actuator of claim 3, wherein the dampening portion is disposed within the housing when the piston rod is in the retracted position.

5. The actuator of claim 4, wherein the cap further defines a groove between the cover portion and the dampening portion, wherein the distal end wall is disposed within the groove when the piston rod is in the retracted position.

6. The actuator of claim 1, wherein the first portion comprises a rectangular cross section as taken through a plane parallel to the central axis. ^Client Docket No.: P-2-00535 WO1 Attorney Docket No.: 10213-294WO1 7. The actuator of claim 6, wherein the second portion comprises a substantially trapezoidal cross section as taken through the plane parallel to the central axis.

8. The actuator of claim 7, wherein the cap further comprises a transition portion, wherein the transition portion is disposed between the first portion and the second portion.

9. The actuator of claim 8, wherein the transition portion comprises a third wall, wherein the third wall extends from the first wall to the second wall.

10. The actuator of claim 9, wherein the transition portion comprises a trapezoidal cross section as taken through the plane parallel to the central axis.

11. The actuator of claim 2, wherein the piston rod is movable from the retracted position to an extended position upon actuation of the gas generator.

12. The actuator of claim 11, wherein the cover portion defines a weakened portion, wherein the piston rod breaks the weakened portion and extends through the cover portion as the piston rod moves from the retracted position to the extended position.

13. The actuator of claim 11, wherein the end wall of the cap is permanently coupled to the distal end of the piston rod.

14. The actuator of claim 13, wherein the cover portion defines a weakened portion, wherein the piston rod breaks the weakened portion and separates the cover portion from the dampening portion as the piston rod moves from the retracted position to the extended position.

15. The actuator of claim 14, wherein the end wall of the cap is permanently coupled to the distal end of the piston rod by an adhesive.

16. The actuator of claim 1, wherein the housing further comprises an outer surface, wherein the housing defines gas relief openings extending from the inner surface to the outer surface. ^Client Docket No.: P-2-00535 WO1 Attorney Docket No.: 10213-294WO1 17. The actuator of claim 16, further comprising a sleeve, the sleeve covering the gas relief openings.

18. The actuator of claim 17, wherein the sleeve comprises acrylonitrile butadiene styrene (ABS).

19. The actuator of claim 17, wherein the sleeve defines a shoulder, wherein the proximal end of the piston rod abuts the shoulder when the piston rod is in the retracted position.

20. The actuator of claim 1, wherein the cap comprises an elastic material. ^

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