Dispensing module, applicator head and nozzle holder for dispensing a fluid, in particular hot-melt adhesive

Abstract

The invention relates to a dispensing module (1) for an applicator head for dispensing a fluid, in particular hot-melt adhesive, comprising a module housing (5), a valve body accommodated in the module housing (5), an adapter (7) through which the valve body extends, comprising a proximal end (49) and a distal end (41), the distal end (41) being connected by means of a screw connection (51) to the module housing (5), a nozzle holder (9) which is adapted to be inserted into a matching recess in a base member of the applicator head, and one or a plurality of sealing elements (57, 59, 61) for sealing the nozzle holder (9) and the base member against each other in a fluid-tight manner. According to the invention, it is proposed that the nozzle holder (9) comprises a cavity (69) through which the valve body extends, is connected by means of a screw connection (51) to the proximal end (49) of the adapter (7), comprises a valve seat (79) which is adapted to cooperate with a valve head (31) of the valve body, and comprises an elongate section (75) upstream from the valve seat (79), within which the cavity (69) is limited to a narrow gap (77).

Claims

1. A dispensing module for use with an applicator head having a base member with a recess for dispensing hot-melt adhesive, the dispensing module comprising: a module housing; a valve body having a valve stem terminating in a valve head; an adapter through which said valve body extends and having a proximal end and a distal end, said distal end being connected to said module housing; a nozzle holder configured to be inserted into the recess in the base member of the applicator head; and one or more sealing elements for sealing said nozzle holder and the base member against each other in a fluid-tight manner, wherein said nozzle holder comprises: a cavity through which said valve body extends, wherein said nozzle holder is connected to said proximal end of said adapter, said cavity comprising a first portion having a first enlarged cross-section and a second portion having a second reduced cross-section, said second reduced cross-section being smaller than said first enlarged cross-section, and said second portion further having a length over which the second portion's second reduced cross-section is constant, a valve seat configured to cooperate with said valve head of said valve body, wherein the amount of fluid passing between said valve seat and said valve head depends on the pressure drop produced by opening said valve seat and said valve head, and an elongate section, having a length and positioned upstream from said valve seat, wherein, along said length of said elongate section, said second portion of the cavity with the second reduced cross-section forms a narrow gap, said narrow gap having a width such that the pressure drop already occurs when said hot-melt adhesive is flowing through said narrow gap, and said length of said elongate section is a multiple greater than one of said width of said narrow gap, wherein said valve stem has a constant cross-section along its axial length overlapping with said second portion of the cavity, and wherein said valve body is movable to an open position when said valve head is moved away from said valve seat in a downward direction.

2. The dispensing module according to claim 1, in which said length of said elongate section is in a range of 14 to 20 times said width of said narrow gap.

3. The dispensing module according to claim 2, wherein said width of said narrow gap is in a range between 0.3 mm and 0.5 mm.

4. The dispensing module according to claim 1, wherein said elongate section is disposed adjacent to said valve seat.

5. The dispensing module according to claim 1, wherein said valve body is movable between a closed position in which said valve head is in fluid-tight contact with said valve seat, and said open position, said closed position and said open position being spaced apart from each other by a stroke, and the orifice, which is released by means of the stroke, being larger than that of the said narrow gap.

6. The dispensing module according to claim 1, wherein said valve seat comprises a seat surface having an aperture angle in the range between 120 and 140.

7. The dispensing module according to claim 6, wherein said valve head comprises a surface matching said seat surface of the valve seat and having an aperture angle between 115 and 140.

8. The dispensing module according to claim 1, wherein said adapter comprises a positioning element at said distal end and said module housing comprises a matching positioning element.

9. The dispensing module according to claim 8, wherein said adapter comprises a positioning element at said proximal end and said nozzle holder comprises a matching positioning element.

10. The dispensing module according to claim 1, wherein said elongate section is adjacent to said valve seat.

Description

(1) The invention is described in greater detail hereinafter by means of preferred embodiments and with reference to the accompanying Figures in which:

(2) FIG. 1 shows a perspective view of the dispensing module according to the invention in a preferred embodiment,

(3) FIG. 2 shows a partly sectional side view of the dispensing module of FIG. 1,

(4) FIG. 3 shows a view on an enlarged scale of a part of the structure shown in FIG. 2,

(5) FIG. 4 shows a further detail view of the structure of FIG. 2, and

(6) FIG. 5 shows a detail view on an enlarged scale of the structure in FIGS. 2 and 4.

(7) FIG. 1 shows a dispensing module 1. The dispensing module 1 has an actuator 3 which in the present example is in the form of a solenoid valve. The actuator 3 is connected to a module housing 5 of the dispensing module 1. The dispensing module 1 also has an adapter 7 connected to the module housing 5. A nozzle holder 9 is connected to the adapter 7 of the dispensing module 1.

(8) Provided on the actuator 3 is a connector socket 19 having an electrical connection 11 for the feed of electric energy for controlling the actuator 3. In the present embodiment the module housing 5 is of a two-part structure. In this embodiment the two-part module housing has a cylinder housing 13 and a housing cover 15. A sound damper 17 is provided in the housing cover 15. It is screwed into the housing cover 15 of the module housing.

(9) FIG. 2 shows a side view of the dispensing module 1 of FIG. 1. In regard to repeated references attention is directed to the description relating to FIG. 1. That also applies to the other Figures and references which are repeated therein. A part of the dispensing module 1 in FIG. 2 is shown as a sectional view. In particular the Figure shows that arranged between the actuator 3 and the housing cover 15 is an insulating plate 21, by means of which the actuator is connected to the module housing 5 or optionally the housing cover 15. Provided between the insulating plate 21 and the module housing 5 is a sealing element 35 which is in the form of a sealing plate and which extends around a multiplicity of bores. Alternatively, respective individual sealing elements could be provided here, but for reasons of manufacture and assembly it is deemed to be preferable to provide an individual sealing element which seals off those multiplicity of bores. Provided within the cylinder housing 13 are a first conduit 23 for a control fluid, for example air, and a second conduit 25 for a control fluid, for example air. By means of those conduits 23, 25 the dispensing module 1 is adapted to move a valve piston 33. The valve piston is accommodated within the module housing, in particular in a cylindrical portion of the cylinder housing 13. See in that respect also FIG. 3. The valve control of such valves is generally known so that for the sake of clarity there will not be a detailed description here relating to control of the fluid in the conduits 23, 25 by means of the actuator 3.

(10) The adapter 7 has a plurality of recesses 27 which mutually cross and each extend completely through the adapter 7. In that way a valve stem 29 of the valve body is visible from the exterior. In addition the recesses 27 are to be used for assembly purposes. The adapter 7 is screwed to the module housing 5, in particular to the cylinder housing 13 of the module housing 5, see in that respect FIG. 3.

(11) The nozzle holder 9 is also screwed to the adapter 7. The valve stem 29 of the valve body extends through the adapter 7 and the nozzle holder 9. At its proximal end the valve body has a valve head 31.

(12) The enlarged view in FIG. 3 showing a first region of the sectional view of the portion shown in FIG. 2 of the dispensing module 1 substantially shows the distal part of the valve arrangement. The valve piston 33 is movable without play in a cylindrical portion 37 within the cylinder housing 13. A return means 39 preferably in the form of a spring holds the valve body in a normally closed position (NC). In that position of the valve piston 33 the valve head 31 (see FIG. 2 and FIG. 4) is in a closed position relative to the valve seat (see FIG. 4). The valve stem 29 has a threaded portion forming a screw connection 38 to a corresponding threaded portion in the valve piston 33. The valve stem 29 is fixedly connected to the valve piston 33 by means of a lock nut 41 and the screw connection 38. Optionally the thread of the screw connection 38 has a reduced pitch.

(13) At a distal end 41 of the adapter 7 the latter is connected to the module housing 5, in particular the cylinder housing 13, by means of a screw connection 43. At the distal end 41 the adapter 7 has a positioning element 45 in the form of a centering shoulder. In the assembled condition shown in FIG. 3 the positioning element 45 co-operates with a positioning element 47, in the form of a centering bore, of the module housing 5, in particular the cylinder housing 13. In that way the adapter 7 is connected to the module housing 5 free of play and in a definitely positioned relationship.

(14) The adapter 7 further has a proximal end 49 at which the adapter 7 and the nozzle holder 9 are connected by means of a screw connection 51. In the region of the proximal end 49, the adapter also has a positioning element 53 in the form of a centering shoulder and co-operating with a corresponding positioning element 55 in the form of a centering bore in the nozzle holder 9. At its peripheral surface the nozzle holder has a plurality of blind holes 63. The blind holes 63 are adapted for accommodating corresponding engagement elements of an assembly and disassembly tool, for example an assembly wrench.

(15) As sealing means, the nozzle holder 9 has a first O-ring 57 and a second O-ring 59 arranged along the periphery of the nozzle holder. In addition, in a preferred embodiment the nozzle holder 9 has an axial sealing element 61 which is in contact with a corresponding surface of the adapter 7 and the nozzle holder 9. Alternatively the nozzle holder may comprise a flange-like end portion, at the surface of which the axial sealing element is correspondingly arranged. It will be noted however that a corresponding surface of the adapter 7 is provided for that purpose in the embodiment of FIG. 3. In addition, in the embodiment of FIG. 3 there is a seal receiving means 65 which permits a simplified arrangement of a radial sealing element. It is pushed into the region of the seal receiving means 65 and positioned and supported by assembly of the nozzle holder 9.

(16) As regards FIGS. 3, 4 and 5, reference is made to the foregoing description with respect to repeated reference signs. FIG. 4 shows a further region of the dispensing module 1 shown in cross section in FIG. 2. FIG. 4 shows in particular details relating to the nozzle holder 9 of the dispensing module 1. The nozzle holder 9 comprises one or more feed openings 67 for the fluid to be dispensed. Provided within the nozzle holder 9 is a cavity 69 for transport of the fluid fed through the feed opening 67. The cavity comprises a first portion 71. In a preferred embodiment an enlarged cross-section is provided in the portion 71. In addition in a further preferred embodiment the valve stem 29 is narrowed in the region 71. Furthermore the cavity comprises a portion 73 of reduced cross-section. Because of the reduction in cross-section in the portion 73 the nozzle holder 9 comprises an elongate region 75. A narrow gap 77 is formed in that elongate region 75. In a preferred alternative the cross-section is not reduced in the portion 73, but the diameter of the valve stem 29 is increased so that this alternative also affords an elongate region with a narrow gap. In a further preferred alternative both the cross-section in the portion 73 is reduced and also the diameter of the valve stem 29 is increased.

(17) Provided at the proximal end of the nozzle holder 9 is a valve seat 79 which in the operative position shown in FIG. 4 is in fluid-tight contact with a contact surface 81 of the valve head 31. In that condition this is referred to as the closed position. The valve head 31 substantially comprises a mushroom-type shape.

(18) FIG. 5, in contrast to FIG. 4, shows the valve in an open position. The valve head 31 has been moved from the closed position into the open position by a stroke X together with the valve stem 29 and the valve piston 33 (not shown). FIG. 5 once again emphasizes the elongate region 75, the length of which is a multiple of the width of the narrow gap 77. The contact surface 81 of the valve head 31 is of a substantially conical configuration, the cone comprising an aperture angle . In FIG. 5 the aperture angle is about 120. An opening of an internal width O has been cleared by movement of the valve head 31 by the stroke X into the open position. In the example shown in FIG. 5, the internal width O is less than a width S of the gap 77. Preferably, the internal width O is half as great as the width of the gap S. Further preferably the internal width O is 0.6 times the gap S and particularly preferably the internal width O is less than the width of the gap S. In the FIG. 5 embodiment the length of the elongate region 75 is approximately 15 times as great as the width S of the narrow gap 77.