Molded piston seal with leak-proof slip line

Abstract

The seal (20) defining the chamber (28) includes a first portion (22), a second portion (24) facing away from the first portion (22), and a central portion (26) between the first and second portions (22, 24). The central portion 26 defines a sealing surface 26a. The seal defines a split line (26b) located between the sealing surface (26a) and one of the first and second portions (22, 24).

Description

[Technical Field]

[0001] The present disclosure relates to seals, and more particularly to piston seals for medical injector metering pumps. [Background technology]

[0002] This application claims priority to U.S. Provisional Application No. 63 / 415,076, entitled "Molded Piston Seal with Anti-Leak Deported Split Line," filed October 11, 2022, the entire disclosure of which is incorporated herein by reference in its entirety.

[0003] Wearable medical devices, such as automatic injectors, have the advantage of providing treatment to patients at locations remote from clinical facilities and / or while worn individually under the patient's clothing. The wearable medical device can be applied to the patient's skin and can be configured to automatically administer a dose of a pharmaceutical composition within a predetermined period of time after applying the wearable medical device to the patient's skin, such as after a 27-hour delay. After the device delivers the pharmaceutical composition to the patient, the patient can subsequently remove and discard the device.

[0004] Automatic injectors typically utilize multiple seals. Many seals used in automatic injectors, such as O-ring type seals, define split lines during manufacturing that require re-machining to create a smooth sealing surface. Re-machining is typically accomplished by drum machining, buffing, or cryogenic machining. Disadvantages include the additional cost associated with re-machining and the potential for surface irregularities that can compromise the integrity of the seal.

[0005] Accordingly, those skilled in the art continue to research and develop the field of seals, and more specifically, piston seals for medical injector metering pumps. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2015 / 157174 Summary of the Invention [Means for solving the problem]

[0007] Disclosed is a seal.

[0008] In one example, the seal defines a chamber and includes a first portion, a second portion facing away from the first flange portion, and a central portion between the first and second portions. The central portion defines a sealing surface. The seal defines a parting line between the sealing surface and one of the first and second portions.

[0009] The first portion, the second portion, and the central portion may be a single monolithic piece. The first portion, the second portion, and the central portion may define an O-ring seal. At least a portion of the seal may be overmolded onto a portion of the piston.

[0010] The split line may be located in the central portion. The split line may be located at an outermost radial portion of the central portion. The central portion of the seal may be toroidal. The seal may include an elastomeric material.

[0011] Also disclosed is a metering pump for a medical injector having a reservoir and a cannula.

[0012] In one example, a metering pump includes a housing, a sleeve at least partially received within the housing, a piston at least partially received within the sleeve, and a seal disposed over a portion of the piston. The seal has a first portion, a second portion facing the first portion, and a central portion located between the first portion and the second portion. The central portion defines a seal surface. The seal defines a slip line located between the seal surface and one of the first portion and the second portion. The metering pump seal may be a single monolithic piece. The metering pump seal may be an O-ring seal. At least a portion of the seal may be overmolded over a portion of the piston. The metering pump seal may include an elastomeric material.

[0013] The split line of the seal may be located at the central portion. The split line of the seal may be located at an outermost radial portion of the central portion. The central portion of the seal may be toroidal.

[0014] The piston and sleeve of the metering pump may define a chamber. The piston may be movable between a first position in which the chamber has a first volume and a second position in which the chamber has a second volume, the first volume being greater than the second volume. The sleeve may be movable between a first rotational position in which the inlet may be in fluid communication with the chamber, a second rotational position in which the outlet may be in fluid communication with the chamber, and a third rotational position in which the inlet and outlet are isolated from the chamber. The seal of the metering pump may be sized and shaped such that the sealing surface may be configured to be movably nested within the sleeve.

[0015] Corresponding reference characters indicate corresponding parts throughout the several views. The illustrations presented herein illustrate exemplary embodiments of the present disclosure, and such illustrations should not be construed as limiting the scope of the present disclosure in any way.

[0016] The above and other features and advantages of the present disclosure, as well as the manner in which they are achieved, will become more apparent, and the disclosure itself will be better understood, by reference to the following description of embodiments of the disclosure taken in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is an exploded view of a rotary metering pump for a medical injector. [Figure 2] FIG. 2 is a perspective view of a rotary metering pump. [Figure 3] FIG. 3 is a perspective view of a portion of the rotary metering pump of FIG. [Figure 4] FIG. 4 is a cross-sectional view of a portion of the rotary metering pump of FIG. [Figure 5] FIG. 5 is a cross-sectional view of a portion of the rotary metering pump of FIG. [Figure 6] 6 is an exploded perspective view of a mold for forming a portion of the rotary metering pump of FIG. 2. FIG. [Figure 7] 7 is an exploded perspective view of a portion of the rotary metering pump of FIG. 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] Corresponding reference characters indicate corresponding parts throughout the several views. The illustrations presented herein illustrate exemplary embodiments of the present disclosure, and such illustrations should not be construed as limiting the scope of the present disclosure in any way.

[0019] Spatial or directional terms such as "left," "right," "inner," "outer," "above," "below," etc. should not be considered limiting as the present invention may assume various alternative orientations.

[0020] All numbers used in the specification and claims should be understood as modified in all instances by the term "about." By "about" is meant a range of plus or minus ten percent of the stated value. As used in the specification and claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. The terms "first," "second," etc. are not intended to refer to any particular order or chronology, but instead refer to different states, properties, or elements. "At least" means "greater than or equal to."

[0021] Referring generally to FIGS. 1 and 2, a metering pump 10 for a medical injector 12 or drug delivery device is shown. The metering pump 10 is a rotary metering pump and is described in U.S. Patent Application Publication No. 2009 / 0129994, the entire contents of which are incorporated herein by reference. The rotary metering pump 10 is connected to a DC motor and gearbox assembly (not shown) configured to rotate a sleeve 14 within a housing 16. The sleeve 14 is provided with a helical groove 32. A coupling pin 34 connected to a piston 18 translates along the helical groove 32 to guide retraction and insertion of the piston 18 within the sleeve 14 as the sleeve 14 rotates in one direction and then the opposite direction, respectively. The sleeve 14 has an end plug 36, as shown in FIG. 7. As shown in FIG. 5, two seals 20 on each end of the piston 18 and end plug 36 within the sleeve 14 define a cavity or chamber 28 when the piston 18 is retracted, following the aspiration stroke and thus ready to dispense. The volume of chamber 28 varies depending on the degree of retraction of piston 18. When piston 18 is fully inserted and seals 20 are substantially in contact with each other after the dispense stroke and therefore ready for aspiration, the volume of chamber 28 is negligible or essentially zero.

[0022] The disclosed seal 20 has leak-proofing properties designed to prevent the formation of leak paths. The seal 20 is designed to contain split lines on the non-sealing surface while keeping the sealing surface free of split lines and potential flash. This may be achieved by moving the split lines away from the sealing surface during manufacturing. In the case of O-ring-type seals overmolded onto a rigid part, the sealing surface may be located at the outermost radial position of the toroid.

[0023] The seal 20 may be formed in a mold 40, as shown in FIG. 6 . The mold 40 may include one or more sections to define each portion of the seal 20. The mold 40 may be designed to eject the molded elastomeric part (i.e., the seal 20) by relying on the reversible elastic deformation of the elastomeric material. In one example, the split line 26b caused by the mating of the mold 40 parts is moved away from the sealing surface. In the case of an O-ring-type seal overmolded to the piston 18, the mold may be configured with at least one portion of a front surface that extends beyond a point in the radial direction such that the split line 26b is away from the outermost radial location that forms the sealing surface when the seal 20 is interference-fitted with a bore-containing component. For example, the split line 26b may be offset from the outermost diameter of the sealing surface 26 by a distance greater than 0.1 mm. In another example, mold 40 includes three bodies that allow for axial split lines, such as longitudinal split line 30, on the non-sealing surface and radial split lines, such as recessed radial split line 32, on the other non-sealing surface.

[0024] Referring to FIGS. 3-4 , the seal 20 may comprise any suitable material for its intended use. In one example, the seal 20 comprises an elastomeric material. The seal 20 is defined by a first portion 22, a second portion 24 facing away from the first portion 22, and a central portion 26 located between the first portion 22 and the second portion 24. The first portion 22 and the second portion 24 may be generally continuous, such that they do not have any grooves or split lines. In another example, one or more of the first portion 22 and the second portion 24 may include one or more spiral grooves or split lines formed during molding. In another example, one of the first portion 22 and the second portion 24 is flanged, or both the first portion 22 and the second portion 24 are flanged.

[0025] The central portion 26 may be generally rounded. In one example, the central portion 26 is toroidal. The central portion 26 defines a sealing surface 26a. The sealing surface 26a is designed to contact a surface, such as a tubular surface, such that the sealing surface 26a nests and forms a seal within the tube. In one example, the sealing surface 26a is continuous, without grooves or split lines, to ensure a proper seal for drawing a vacuum or discharging fluid within the tube. The sealing surface 26a is further configured for sliding engagement with a surface such that the sealing surface 26a can maintain a seal while moving along the surface, such as within a tube or other structure of similar size and shape to the sealing surface 26a.

[0026] Referring to FIG. 4 , the seal 20 defines a split line 26b. The split line 26b is offset from the seal surface 26a so as not to lie on the seal surface 26a and therefore not to impair the sealing characteristics of the seal 20. The split line 26b may be located between the seal surface 26a and one of the first portion 22 and the second portion 24. In one example, the split line 26b is located on a non-sealing surface portion of the central portion 26. In another example, the split line 26b is located on the outermost radial portion of the central portion 26.

[0027] In one example, first portion 22, second portion 24, and central portion 26 are a single monolithic piece. In another example, first portion 22, second portion 24, and central portion 26 define an O-ring seal.

[0028] 2, a metering pump 10 for a medical injector 12 includes a reservoir 6 and a cannula 8 (not shown). The metering pump 10 includes a housing 16, a sleeve 14 at least partially received within the housing 16, a piston 18 at least partially received within the sleeve 14, and a seal 20 disposed over a portion of the piston 18.

[0029] 3 and 4, the seal 20 of the metering pump 10 has a first portion 22, a second portion 24 opposite the first portion 22, and a central portion 26 located between the first portion 22 and the second portion 24. The central portion 26 defines a sealing surface 26a. The seal 20 defines a split line 26b located between the sealing surface 26 and one of the first portion 22 and the second portion 24. The seal 20 is sized and shaped such that the sealing surface 26 is configured to movably nest within the sleeve 14.

[0030] In one example, the piston 18 and the sleeve 14 define a chamber 28 within the housing 16. The piston 18 is movable between a first position in which the chamber has a first volume and a second position in which the chamber has a second volume. In one example, the first volume is greater than the second volume. The sleeve 14 is movable between a first rotational position in which the inlet is in fluid communication with the chamber 28, a second rotational position in which the outlet is in fluid communication with the chamber 28, and a third rotational position in which the inlet and outlet are isolated from the chamber 28.

[0031] With reference to FIG. 7 , in one or more examples, the seal 20 may be configured to mechanically engage with one or more engagement features 38. The one or more engagement features 38 may be on the piston 18 with reference to FIG. 5 or on the end plug 36 with reference to FIG. 7 . For example, as shown in FIG. 7 , the seal 20 may include one or more receiving features 38′ shaped and sized to nest with the engagement features 38. The engagement features 38 and receiving features 38′ may be any shape or geometry, such as tab-shaped, triangular, rounded, rectangular, etc., and are not limited to the plus shape shown in FIG. 7 .

[0032] While the present invention has been described in detail for purposes of illustration, based on what are presently considered to be the most practical and preferred embodiments, it should be understood that such detail is for this purpose only, and that the present invention is not limited to the disclosed embodiments or aspects, but on the contrary, is intended to cover modifications and equivalent arrangements within the spirit and scope of the appended claims. For example, it should be understood that the present invention contemplates that, to the extent possible, one or more features of any embodiment can be combined with one or more features of any other embodiment.

Claims

1. A seal (20) defining a chamber (28), a first portion (22) proximal to said chamber (28); a second portion (24) facing the first portion (22); a central portion (26) between the first portion (22) and the second portion (24), the central portion (26) defining a sealing surface (26a), the seal (20) defining a split line (26b) located between the sealing surface (26) and one of the first portion (22) and the second portion (24).

2. The seal (20) of claim 1, wherein the split line (26b) may be offset from an outermost diameter of the sealing face (26) by a distance greater than 0.1 mm.

3. The seal (20) of claim 1, wherein the first portion (22), the second portion (24), and the central portion (26) are a single monolithic piece.

4. The seal (20) of claim 1, wherein the first portion (22), the second portion (24), and the central portion (26) define an O-ring seal.

5. The seal (20) of claim 1, wherein at least a portion of the seal (20) is overmolded onto a portion of the piston (18).

6. The seal (20) of claim 5, wherein at least a portion of the seal (20) forms a chemical bond with a substrate of the piston (18).

7. The seal (20) of claim 5, wherein the piston (18) comprises at least one engagement feature (38) configured to mechanically engage the seal (20).

8. The seal (20) of claim 1, wherein the split line (26b) is located in the central portion (26).

9. The seal (20) of claim 1, wherein the split line (26b) is located at an outermost radial portion of the central portion (26).

10. The seal (20) of claim 1, wherein the central portion (26) is toroidal.

11. The seal (20) of claim 1, wherein the seal (20) comprises an elastomeric material.

12. A metering pump (10) for a medical injector (12) including a reservoir (6) and a cannula (8), a housing (16); a sleeve (14) at least partially received within said housing (16); a piston (18) at least partially received within the sleeve (14); a seal (20) disposed on a portion of the piston, the seal (20) having a first portion (22), a second portion (24) opposing the first portion (22), and a central portion (26) between the first portion (22) and the second portion (24), the central portion (26) defining a sealing surface (26a), and the seal defining a split line (26b) located between the sealing surface (26) and one of the first portion (22) and the second portion (24).

13. The metering pump (10) of claim 12, wherein the seal (20) is a single monolithic piece.

14. The metering pump (10) of claim 12, wherein the seal (20) is an O-ring seal.

15. The metering pump (10) of claim 12, wherein the seal (20) is overmolded onto the portion of the piston (18).

16. 13. The metering pump (10) of claim 12, wherein the split line (26b) is disposed on the central portion (26).

17. 13. The metering pump (10) of claim 12, wherein the split line (26b) is located at an outermost radial portion of the central portion (26).

18. The metering pump (10) of claim 12, wherein the central portion (26) is toroidal.

19. The metering pump (10) of claim 12, wherein the seal (20) comprises an elastomeric material.

20. 13. The metering pump of claim 12, wherein the piston and the sleeve define a chamber, the piston being movable between a first position in which the chamber has a first volume and a second position in which the chamber has a second volume, the first volume being greater than the second volume, and the sleeve being movable between a first rotational position in which an inlet is in fluid communication with the chamber, a second rotational position in which an outlet is in fluid communication with the chamber, and a third rotational position in which the inlet and outlet are isolated from the chamber.

21. 21. The metering pump (10) of claim 20, wherein the seal (20) is sized and shaped such that the sealing surface (26) is configured to movably nest within the sleeve (14).

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