Molded piston seal with leak-proof offset parting line

Abstract

A seal (20) defining a chamber (28) includes a first portion (22), a second portion (24) opposite 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 parting line (26b) between the sealing surface (26a) and one of the first and second portions (22, 24).

Description

[0001] Cross - reference to related applications

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

[0003] Background of the invention

[0004] Field of the Invention

[0005] The present disclosure relates to a seal, and more particularly, to a piston seal for a medical syringe metering pump.

[0006] Description of the Related Art

[0007] Wearable medical devices (e.g., auto-injectors) have the advantage of providing treatment to a patient when discretely worn at a location remote from a clinical facility and / or under the patient's clothing. A wearable medical device can be applied to a patient's skin and is configured to automatically deliver a dose of a pharmaceutical composition after a predetermined period of time (e.g., after a 27-hour delay) following application of the wearable medical device to the patient's skin. After the device delivers the pharmaceutical composition to the patient, the patient can then remove and dispose of the device.

[0008] Auto-injectors typically employ multiple seals. Many seals used in auto-injectors (e.g., O-ring type seals) define a split line during manufacturing that requires reworking to form a smooth sealing surface. This reworking is typically accomplished by sanding, polishing, or cryo-machining. Disadvantages include the additional cost associated with reworking and potential surface irregularities that can compromise the integrity of the seal.

[0009] Accordingly, those skilled in the art continue to research and develop in the field of seals, and more particularly, research and development of piston seals for medical syringe metering pumps. Summary of the Invention

[0010] A seal is disclosed.

[0011] In one example, the seal defines a chamber and includes a first portion, a second portion opposite the first flange portion, and a central portion located between the first portion and the second portion. The central portion defines a sealing surface. The seal defines a parting line that is located between the sealing surface and one of the first portion and the second portion.

[0012] The first portion, the second portion, and the central portion can be a single integral piece. The first portion, the second portion, and the central portion can define an O-ring seal. At least a portion of the seal can be over-molded on a portion of the piston.

[0013] The parting line can be located on the central portion. The parting line can be located on the outermost radial portion of the central portion. The central portion of the seal can be annular. The seal can include an elastomeric material.

[0014] Also disclosed is a metering pump for a medical syringe, the medical syringe having a reservoir and a barrel.

[0015] In one example, the metering pump includes a housing, a sleeve, a piston, and a seal, the sleeve being at least partially received within the housing, the piston being at least partially received within the sleeve, and the seal being positioned on a portion of the piston. The seal has a first portion, a second portion opposite the first portion, and a central portion located between the first portion and the second portion. The central portion defines a sealing surface. The seal defines a parting line that is located between the sealing surface and one of the first portion and the second portion. The seal of the metering pump can be a single integral piece. The seal of the metering pump can be an O-ring seal. At least a portion of the seal can be over-molded on that portion of the piston. The seal of the metering pump can include an elastomeric material.

[0016] The parting line of the seal can be located on the central portion. The parting line of the seal can be located on the outermost radial portion of the central portion. The central portion of the seal can be annular.

[0017] The piston and the sleeve of the metering pump can define a chamber. The piston can be movable between a first position and a second position, in the first position, the chamber having a first volume, and in the second position, the chamber having a second volume, the first volume being greater than the second volume. The sleeve can be movable between a first rotational position, a second rotational position, and a third rotational position, in the first rotational position, an inlet being in fluid communication with the chamber, in the second rotational position, an outlet being in fluid communication with the chamber, and in the third rotational position, the inlet and the outlet being isolated from the chamber. The size and shape of the seal of the metering pump can be designed such that the sealing surface can be configured to movably nest within the sleeve.

[0018] In all of the several views, corresponding reference numerals denote corresponding parts. The examples presented herein illustrate exemplary embodiments of the present disclosure, and such examples should not be construed as limiting the scope of the present disclosure in any way. Description of the Drawings

[0019] The above and other features, advantages, and ways of achieving these features and advantages of the present disclosure will become more apparent and the present disclosure itself will be better understood by reference to the following description of embodiments of the present disclosure in conjunction with the accompanying drawings, in which:

[0020] Figure 1 is an exploded view of a rotary metering pump for a medical syringe;

[0021] Figure 2 is a perspective view of the rotary metering pump;

[0022] Figure 3 is Figure 2 a perspective view of a part of the rotary metering pump;

[0023] Figure 4 is Figure 2 a cross-sectional view of a part of the rotary metering pump;

[0024] Figure 5 is Figure 2 a cross-sectional view of a part of the rotary metering pump;

[0025] Figure 6 is for forming Figure 2 an exploded perspective view of a mold for a part of the rotary metering pump; and

[0026] Figure 7 is Figure 2 an exploded perspective view of a part of the rotary metering pump.

[0027] In all of the several views, corresponding reference numerals denote corresponding parts. The examples presented herein illustrate exemplary embodiments of the present disclosure, and such examples should not be construed as limiting the scope of the present disclosure in any way. Detailed Description

[0028] Spatial or directional terms such as “left,” “right,” “inner,” “outer,” “above,” “below,” etc. should not be considered restrictive since the present invention may assume various alternative orientations.

[0029] All numbers used in the specification and claims should be understood to be modified in all instances by the term "about". "About" refers to a range of plus or minus ten percent of the recited 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. do not refer to any particular order or sequence, but rather to different conditions, characteristics, or elements. The phrase "at least" means "greater than or equal to".

[0030] Generally referring to Figure 1 and Figure 2 , there is shown a metering pump 10 for a medical syringe 12 or a drug delivery device. The metering pump 10 is a rotary metering pump as described in International Publication No. WO 2015 / 157174, the entire content of which is incorporated herein by reference. The rotary metering pump 10 is configured to be connected to a DC motor and a gearbox assembly (not shown) to rotate a sleeve 14 within a housing 16. A helical groove 32 is provided on the sleeve 14. When the sleeve 14 rotates in one direction and then in the opposite direction, a coupling pin 34 connected to a piston 18 translates along the helical groove 32 to respectively guide the piston 18 to retract and insert within the sleeve 14. See Figure 7 , the sleeve 14 has end plugs 36. As Figure 5 shown, when the piston 18 retracts after a suction stroke and is thus ready for dispensing, two seals 20 located on the respective ends of the piston 18 and the end plugs 36 and within the sleeve 14 define a cavity or chamber 28. The volume of the chamber 28 changes according to the degree of retraction of the piston 18. When the piston 18 is fully inserted after a dispensing stroke and the seals 20 are substantially in contact with each other and are thus ready for suction, the volume of the chamber 28 can be negligible or substantially zero.

[0031] The seals 20 disclosed have leak - prevention characteristics that are designed to prevent the formation of leak paths. The seals 20 are designed to include a parting line on a non - sealing surface while keeping the sealing surface free of parting lines and potential flash. This can be achieved during manufacturing by moving the parting line away from the sealing surface. In the case where an O - ring type seal is overmolded onto a rigid part, the sealing surface can be located at the outermost radial position of the ring.

[0032] See Figure 6, the seal 20 can be formed using a mold 40. The mold 40 can include one or more sections for defining each part of the seal 20. The mold 40 can be designed to eject the molded elastomeric part (i.e., the seal 20) by relying on the reversible elastic deformation of the elastomeric material during ejection. In one example, the parting line 26b caused by the intersection of the mold 40 parts is moved away from the sealing surface. In the case where an O-ring type seal is overmolded on the piston 18, the mold includes at least one part having a front surface extending beyond the radial point. For example, when there is an interference fit with a component including a hole, the parting line 26b is offset from the outermost radial dimension forming the sealing surface. For example, the parting line 26b can be offset from the outermost diameter of the sealing surface 26 by a distance greater than 0.1 millimeter (mm). In another example, the mold 40 includes three bodies, allowing for an axial parting line (e.g., the longitudinal parting line 30) on a non-sealing surface and a radial parting line (e.g., the offset radial parting line 32) on other non-sealing surfaces.

[0033] Reference Figure 3 and Figure 4 , the seal 20 can include any suitable material for the intended application. In one example, the seal 20 includes an elastomeric material. The seal 20 is defined by a first part 22, a second part 24 opposite the first part 22, and a central part 26 located between the first part 22 and the second part 24. The first part 22 and the second part 24 can be substantially continuous such that the first part and the second part do not have any grooves or parting lines. In another example, one or more of the first part 22 and the second part 24 can include one or more helical grooves or parting lines formed during molding. In another example, one of the first part 22 and the second part 24 is flanged, or both the first part 22 and the second part 24 are flanged.

[0034] The central part 26 can be substantially rounded. In one example, the central part 26 is annular. The central part 26 defines a sealing surface 26a. The sealing surface 26a is designed to contact a surface (e.g., a tubular surface) such that the sealing surface 26a nests within the tube and forms a seal within the tube. In one example, the sealing surface 26a is continuous such that the sealing surface does not have any grooves or parting lines to ensure a proper seal for evacuating the tube or dispensing fluid within the tube. The sealing surface 26a is also configured to slidably engage with the surface such that the sealing surface can maintain a seal when moving along the surface (e.g., the interior of the tube or other structures having a similar size and shape to the sealing surface 26a).

[0035] Reference Figure 4, the seal 20 defines a parting line 26b. The parting line 26b is offset from the sealing surface 26a such that the parting line is not located on the sealing surface 26a and thus does not compromise any sealing performance of the seal 20. The parting line 26b may be located between the sealing surface 26a and one of the first part 22 and the second part 24. In one example, the parting line 26b is located on a non-sealing surface portion of the central portion 26. In another example, the parting line 26b is located on the outermost radial portion of the central portion 26.

[0036] In one example, the first part 22, the second part 24, and the central portion 26 are a single integral piece. In another example, the first part 22, the second part 24, and the central portion 26 define an O-ring seal.

[0037] Return reference Figure 2 , a metering pump 10 for a medical syringe 12 is disclosed, the medical syringe including a reservoir 6 and a cannula 8 (not shown). The metering pump 10 includes a housing 16, a sleeve 14, a piston 18, and a seal 20, the sleeve being at least partially received within the housing 16, the piston being at least partially received within the sleeve 14, and the seal being positioned on a portion of the piston.

[0038] As Figure 3 and Figure 4 shown, the seal 20 of the metering pump 10 has a first part 22, a second part 24 opposite the first part 22, and a central portion 26 located between the first part 22 and the second part 24. The central portion 26 defines a sealing surface 26a. The seal 20 defines a parting line 26b that is located between the sealing surface 26 and one of the first part 22 and the second part 24. The size and shape of the seal 20 are designed such that the sealing surface 26 is configured to be movably nested within the sleeve 14.

[0039] 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 and a second position, where in the first position the chamber has a first volume and in the second position the chamber has a second volume. In one example, the first volume is greater than the second volume. The sleeve is movable between a first rotational position, a second rotational position, and a third rotational position, where in the first rotational position the inlet is in fluid communication with the chamber 28, in the second rotational position the outlet is in fluid communication with the chamber 28, and in the third rotational position the inlet and the outlet are isolated from the chamber 28.

[0040] Reference Figure 7 , in one or more examples, the seal 20 may be configured to mechanically engage one or more engagement features 38. The one or more engagement features 38 may be located on the piston 18 (see Figure 5) or end plug 36 (see Figure 7 ) thereon. For example, as Figure 7 shown, the seal 20 may include one or more receiving features 38′ that are shaped and sized to nest with the engagement feature 38. The engagement feature 38 and the receiving feature 38′ may have any shape or geometry, such as plate-like, triangular, circular, rectangular, and are not limited to Figure 7 the plus shape shown therein.

[0041] Although, for purposes of illustration, the present invention has been described in detail based on the presently considered to be the most practical and preferred embodiments, it is to be understood that such detail is for that purpose only and that the present invention is not limited to the disclosed embodiments, but rather, the present invention is intended to cover modifications and equivalent arrangements within the spirit and scope of the appended claims. For example, it is to be understood that it is contemplated by the present invention that, to the extent possible, one or more features of any embodiment may be combined with one or more features of any other embodiment.

Claims

1. A seal (20), the seal defining a chamber (28), the seal (20) comprising: a first portion (22) adjacent to the chamber (28); a second portion (24) opposite to the first portion (22); and a central portion (26) located between the first portion (22) and the second portion (24), the central portion (26) defining a sealing surface (26a), the seal (20) defining a parting line (26b) located between the sealing surface (26) and one of the first portion (22) and the second portion (24).

2. The seal (20) according to claim 1, wherein the parting line (26b) can deviate from the outermost diameter of the sealing surface 26 by a distance greater than 0.1 mm.

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

4. The seal (20) according to 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) according to claim 1, wherein at least a portion of the seal (20) is overmolded on a portion of the piston (18).

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

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

8. The seal (20) according to claim 1, wherein the parting line (26b) is located on the central portion (26).

9. The seal (20) according to claim 1, wherein the parting line (26b) is located on the outermost radial portion of the central portion (26).

10. The seal (20) according to claim 1, wherein the central portion (26) is annular.

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

12. A metering pump (10) for a medical syringe (12), the medical syringe comprising a reservoir (6) and a barrel (8), the metering pump (10) comprising: 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) positioned on a portion of the piston, the seal (20) having 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) defining a sealing surface (26a), the seal defining a parting 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) according to claim 12, wherein, the seal (20) is a single integral piece.

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

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

16. The metering pump (10) according to claim 12, wherein, the parting line (26b) is located on the central portion (26).

17. The metering pump (10) according to claim 12, wherein, the parting line (26b) is located on the outermost radial portion of the central portion (26).

18. The metering pump (10) according to claim 12, wherein, the central portion (26) is annular.

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

20. The metering pump (10) according to claim 12, wherein, the piston and the sleeve (14) define a chamber (28), the piston (18) being movable between a first position and a second position, in the first position, the chamber having a first volume, in the second position, the chamber having a second volume, the first volume being greater than the second volume, the sleeve (14) being movable between a first rotational position, a second rotational position and a third rotational position, in the first rotational position, an inlet being in fluid communication with the chamber (28), in the second rotational position, an outlet being in fluid communication with the chamber, in the third rotational position, the inlet and the outlet being isolated from the chamber (28).

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

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