FLUID APPLICATOR HAVING A VALVE MODULE WITH A FLOATING MEMBER AND THE VALVE MODULE

Abstract

A valve module with floating member for use in a fluid applicator and a fluid applicator comprising said valve module are disclosed. The fluid applicator further includes a valve module that is configured to control a flow of fluid from the chamber to the cavity. The valve module includes an upper valve seat and a valve stem operatively coupled to the drive pin and extending from the chamber to the cavity. The valve module further includes a retaining tip attached to the valve stem and a floating member disposed in the cavity between the opening and the retaining tip such that the valve stem passes through the floating member and the floating member is movable along a longitudinal axis of the valve stem.

Claims

1. A method of controlling a flow of fluid from a chamber of a fluid applicator to a cavity of said fluid applicator, said cavity having an upper valve seat via which fluid enters said cavity and an outlet via which fluid is dispensed, the method comprising: moving a valve stem, in a direction away from said upper valve seat and along a longitudinal axis of said valve stem, to a first position; and moving said valve stem, in the direction away from said upper valve seat and along said longitudinal axis of said valve stem, from said first position to a second position, wherein said second position is a greater distance from said upper valve seat than said first position, wherein said valve stem comprises a retaining tip disposed within said cavity, and wherein a floating member, disposed within said cavity between said upper valve seat and said retaining tip and through which said valve stem passes, is caused to move, at least in part, along said longitudinal axis of said valve stem by at least one of moving said valve stem to said first position and moving said valve stem from said first position to said second position.

2. The method of claim 1, wherein moving said valve stem to said first position comprises moving said valve stem from a closed position in which said floating member is engaged with said upper valve seat.

3. The method of claim 2, wherein said floating member is in contact with said retaining tip in said closed position.

4. The method of claim 3, wherein moving said valve stem to said first position causes said floating member to disengage from the upper valve seat.

5. The method of claim 4, wherein moving said valve stem to said first position further causes said floating member to remain in contact with said retaining tip.

6. The method of claim 5, wherein moving said valve stem from said first position to said second position further causes said floating member to move, along said longitudinal axis of said valve stem, towards said upper valve seat.

7. The method of claim 6, wherein said floating member moving towards said upper valve seat is caused, at least in part, by pressure in said cavity exceeding pressure in said chamber, wherein said pressure in said cavity exceeding said pressure in said chamber is caused, at least in part, by moving said valve stem from said first position to said second position.

8. The method of claim 7, wherein moving said valve stem from said first position to said second position further causes said floating member to reengage with said upper valve seat.

9. The method of claim 8, wherein moving said valve stem from said first position to said second position comprises positioning said valve stem at said second position, the second position being the maximum travel of said valve stem from said upper valve seat, and positioning said valve stem at said second position causes, subsequent to said floating member reengaging with said upper valve seat, said floating member to disengage from said upper valve seat.

10. The method of claim 9, wherein said floating member disengaging from said upper valve seat is responsive to said pressure in said cavity equaling said pressure in said chamber, wherein said pressure in said cavity equaling said pressure in said chamber is caused, at least in part, by positioning said valve stem at said second position.

11. The method of claim 9, wherein positioning said valve stem at said second position further causes said floating member to move away from said upper valve seat until contacting said retaining tip.

12. The method of claim 11, further comprising: moving said valve stem, towards said upper valve seat, from said second position to a third position.

13. The method of claim 12, wherein moving said valve stem from said second position to said third position causes said floating member to move towards said upper valve seat.

14. The method of claim 13, wherein moving said valve stem from said second position to said third position causes said floating member to reengage said upper valve seat.

15. The method of claim 1, wherein said floating member has an inner surface and a spacing is defined between said inner surface of said floating member and said valve stem.

16. The method of claim 1, wherein said floating member is spherical and said valve stem passes through the center of said sphere.

17. The method of claim 1, wherein said valve stem has a terminal end and said retaining tip is attached to said terminal end of said valve stem.

18. The method of claim 17, wherein said cavity comprises a lower valve seat and said retaining tip has a conical bottom surface generally parallel to the surface of said lower valve seat of said cavity.

19. The method of claim 1, wherein said retaining tip is configured with a flat upper surface generally perpendicular to said longitudinal axis of said valve stem.

20. The method of claim 1, wherein movement of said valve stem is caused by reciprocal movement of a drive pin disposed in said chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The following detailed description is better understood when read in conjunction with the appended drawings. For the purposes of illustration, examples are shown in the drawings; however, the subject matter is not limited to the specific elements and instrumentalities disclosed. In the drawings:

[0016] FIG. 1 illustrates a fluid applicator according to an embodiment of the present disclosure; and

[0017] FIGS. 2-7 illustrate a close-up view of the valve module in various positions.

DETAILED DESCRIPTION

[0018] FIGS. 1-7 illustrate an exemplary embodiment of a fluid applicator 12 having a valve module 10. The fluid applicator 12 is configured to dispense small, intermittent quantities of a fluid, such as an adhesive. The fluid applicator 12 includes a body 14 in which the valve module 10 and other various dispensing mechanisms are disposed. A fluid inlet 16, disposed within the body 14, supplies an outer fluid chamber 18 with a pressurized fluid. The outer fluid chamber 18 is defined on its outer perimeter by the body 14 and on its inner perimeter by an outer surface of a divider 20, of which the outer fluid chamber 18 annularly surrounds. The outer fluid chamber 18 is fluidly connected to an inner fluid chamber 22 via one or more passageways 24. The inner fluid chamber 22 is generally defined by an inner surface of the divider 20. Accordingly, the outer fluid chamber 18 concentrically surrounds the inner fluid chamber 22. In an alternative embodiment, the outer fluid chamber 18 may be omitted entirely and the fluid inlet 16 may instead connect directly to the inner fluid chamber 22.

[0019] The inner fluid chamber 22 includes an upper portion 26, a middle portion 28, and a lower portion 30. The upper portion 26 includes the openings to the passageways 24 through which fluid is received from the outer fluid chamber 18. The upper portion 26 further abuts on its upper-most end with the body of an actuator 32 providing a reciprocal movement of a drive pin 34 and valve stem 36 and thus effectuating the operation of the valve module 10, as will be discussed in greater detail below. A sealing assembly including a backup ring 35 (e.g., a rubber O-ring) and a spring-energized lip seal 37 provides a fluid seal with the drive pin 34, sealing and isolating the upper portion 26 of the inner fluid chamber 22 (and the inner fluid chamber 22 in general) from the actuator 32.

[0020] The drive pin 34 is operatively coupled with the actuator 32, which causes movement of the drive pin 34 and valve stem 36 along their respective longitudinal axes. The actuator 32 may comprise, for example, a piezoelectric actuator, a pneumatic actuator, a solenoid actuator, or any other type of suitable actuator. The drive pin 34 extends through the inner fluid chamber 22 and includes the valve stem 36 at the position generally corresponding to the valve module 10. While the drive pin 34 and the valve stem 36 are integrally formed in the embodiment shown in FIG. 1, the drive pin 34 and the valve stem 36 may instead be formed as separate, operatively coupled components. The diameter of the valve stem 36 is less than the diameter of the drive pin 34. In particular, the diameter of the portion of the valve stem 36 upon which the floating member 48 moves is less than the diameter of the portion of the drive pin 34 that is inside the inner fluid chamber 22.

[0021] The middle portion 28 of the inner fluid chamber 22 is formed in an elongate, cylindrical shape and narrows to the lower portion 30 of the inner fluid chamber 22. The lower portion 30 of the inner fluid chamber 22 adjoins, at the perimeter of an opening 38 defining an upper valve seat 40, a cavity 42. As will be discussed in greater detail below, the cavity 42 receives fluid from the inner fluid chamber 22 upon disengagement of the floating member 48 and the upper valve seat 40. The cavity 42 in the depicted embodiment is defined by the body 14 of the fluid applicator 12. The cavity 42 is in fluid communication with a fluid outlet 46 disposed at the bottom of a lower valve seat 54 defining the bottom end of the cavity 42. The fluid outlet 46, in turn, leads to the exterior of the fluid applicator 12 whereat a substrate may be positioned to receive the fluid dispensed from the fluid outlet 46.

[0022] The valve stem 36 extends through the opening 38 of the upper valve seat 40 and includes a retaining tip 44 on the valve stem's 36 terminal end. The retaining tip 44 serves, at least in part, to restrict the downward movement of a floating member 48 movably disposed on the valve stem 36. The retaining tip 44 is generally cylindrical- or disc-shaped and includes a flat upper surface 50, the plane of which is generally perpendicular to the longitudinal axis of the valve stem 36. The bottom surface 52 of the retaining tip 44 is formed in a generally conical shape such that the bottom surface 52 is generally parallel with the surface of the lower valve seat 54 of the cavity 42. In some aspects, the retaining tip 44 may be integrally formed with the valve stem 36.

[0023] The spherical floating member 48 is positioned on the valve stem 36 such that the valve stem 36 passes through a hole 56 in the floating member 48. The valve stem 36 and/or the hole 56 in the floating member 48 are sized or otherwise configured for the floating member 48 to freely move up and down on the valve stem 36 according to the various pressures (described in detail below) exerted on the floating member 48 by the flow of the fluid in the valve module 10 and subject to the bounds imposed by the retaining tip 44 below the floating member 48 and the upper valve seat 40 above the floating member 48. In the embodiment shown, a spacing 58 is created between the valve stem 36 and an inner surface 57 of the floating member 48, thus allowing some fluid to pass therethrough when the valve module 10 is in an open position. In other aspects, the inner surface of the floating member 48 may be flush against the valve stem 36 (yet still movable), thereby precluding the spacing 58.

[0024] The floating member 48 and the upper valve seat 40 are cooperatively configured to provide a fluid seal between the inner fluid chamber 22 and the cavity 42 when the floating member 48 is retained flush against the upper valve seat 40 by the upward movement or force imparted by the retaining tip 44 of the valve stem 36. Similarly, the contact between the floating member 48 and the upper surface 50 of the retaining tip 44 prevents the flow of any fluid from within the spacing 58 between the inner surface 57 of the floating member 48 and the valve stem 36.

[0025] FIGS. 2-7 illustrate a close-up side view of the valve module 10 in various states during a dispensing operation. In FIG. 2, the valve module 10 is depicted in a closed position. The valve stem 36 is held at its upper-most position by operation of the actuator 32 and/or the biasing element 37. Accordingly, the floating member 48 is positioned in contact with the upper valve seat 40 to provide a fluid seal and thereby prevent the flow of fluid from the inner fluid chamber 22 into the cavity 42. The floating member 48 is also held in contact with the upper surface 50 of the retaining tip 44 to prevent fluid flow from the spacing 58 between the valve stem 36 and the inner surface 57 of the floating member 48.

[0026] In FIG. 3, the process of opening the valve module 10 is initiated. Namely, in a first open position, driven by the actuator 32, the valve stem 36 and the attached retaining tip 44 move downward toward the fluid outlet 46. Under a supply pressure P.sub.1 in the inner fluid chamber 22, the floating member 48 is forced downward in conjunction with the retaining tip 44 and out of engagement with the upper valve seat 40. Since the floating member 48 is disengaged with the upper valve seat 40, the fluid from the inner fluid chamber 22 begins to flow into the cavity 42, thereby affecting a cavity pressure P.sub.2 in the cavity 42.

[0027] In FIG. 4 and in a second open position, the floating member 48 begins to move back upwards towards the upper valve seat 40. This occurs when the cavity pressure P.sub.2 in the cavity 42, increased by the flow of fluid from the inner fluid chamber 22 and the downward movement of the valve stem 36 and the retaining tip 44 (which positively displace additional fluid), exceeds the supply pressure P.sub.1 in the inner fluid chamber 22.

[0028] In FIG. 5 and in a third open position, the retaining tip 44 and valve stem 36 continue to move downward toward the fluid outlet 46 and the floating member 48 re-seats with the upper valve seat 40 due to the higher cavity pressure P.sub.2 in the cavity 42 relative to the supply pressure P.sub.1. The cavity pressure P.sub.2 exceeding the supply pressure P.sub.1 is caused by the positive displacement of the retaining tip 44, which at the typical opening velocity is greater than a steady state flow through the cavity 42. During this time in which the floating member 48 is reseated with the upper valve seat 40 and the valve stem 36 and retaining tip 44 are still moving downward, the flow of fluid from the cavity 42 and through the fluid outlet 46 is driven primarily by the movement of the valve stem 36 and the retaining tip 44. Notably, the floating member 48 moving upwards and re-engaging the upper valve seat 40 due to the cavity pressure P.sub.2 being greater than the supply pressure P.sub.1, as shown in FIGS. 4 and 5, serves to prevent or lessen the aforementioned hammerhead effect (i.e., the undesirable and disproportionately large quantity of fluid dispensed at the start of a dispensing operation) by restricting fluid flow from the inner fluid chamber 22 until the cavity pressure P.sub.2 is reduced to a level equaling that of the supply pressure P.sub.1.

[0029] In FIG. 6 and in fourth open position, the valve stem 36 and retaining tip 44 reach their lower-most position and stop their downward movement. The cavity pressure P.sub.2 equalizes with the supply pressure P.sub.1 since there is no longer a positive displacement of fluid caused by motion of the valve stem 36 and the retaining tip 44. Accordingly, the floating member 48 disengages with the upper valve seat 40 and moves downward until coming into contact with the retaining tip 44 as fluid flows past the floating member 48 in the cavity 42 and through the fluid outlet 46.

[0030] In a fifth open position (not shown), the floating member 48 engages with and remains in contact with the retaining tip 44 until the end of the dispensing operation (i.e., until the valve stem 36 and retaining tip 44 begin to move back upwards towards the upper valve seat 40). The floating member 48 is moved into engagement with the retaining tip 44 due to the cavity pressure P.sub.2 continuing to increase above the supply pressure P.sub.1, which is caused by the restriction between the upper valve seat 40 and the valve stem 36.

[0031] In FIG. 7, to conclude the dispensing operation, the valve stem 36 and retaining tip 44, and thereby also the floating member 48, are moved upward until the floating member 48 engages the upper valve seat 40 to stop fluid flow from the inner fluid chamber 22. The upper surface 50 of the retaining tip 44 is also brought into contact with the bottom of the floating member 48 to prevent fluid flow from the spacing 58 between the inner surface 57 of the floating member 48 and the valve stem 36.

[0032] It will be appreciated that the foregoing description provides examples of the disclosed system and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the foregoing examples. All references to the disclosure or examples thereof are intended to reference the particular example being discussed at that point and are not intended to imply any limitation as to the scope of the disclosure more generally. All language of distinction and disparagement with respect to certain features is intended to indicate a lack of preference for those features, but not to exclude such from the scope of the disclosure entirely unless otherwise indicated.

[0033] Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. Use of the term generally or the like with respect to any characteristic shall be understood to mean a variation of plus or minus 10% with respect to that characteristic All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.