Device and method for dispensing a flowable medium

Abstract

A device and method for dispensing a flowable medium has a housing with an interior space and a rod mounted in the housing that is movable between a first end position and a second end position and passes through a diaphragm mounted in a sealed manner in the housing radially on the outside and in the rod radially on the inside. The diaphragm divides the interior space into a first cavity and a second cavity separated from the first cavity in a fluid tight manner. The flowable medium can flow through at least one channel that opens into the first cavity, and is dispensed through a dispensing opening. A sealing section of the rod closes the dispensing opening in the first end position and is at a distance from the dispensing opening in the second end position. A pressure medium acts on the diaphragm in the second cavity.

Claims

1. A device for dispensing a flowable medium comprising: a housing with an interior space; a rod mounted in the housing, wherein the rod is movable between a first end position and a second end position in an axial direction; a diaphragm, wherein the rod passes through the diaphragm, wherein the diaphragm is mounted in a sealed manner in the housing radially on the outside and is mounted in a sealed manner in the rod radially on the inside, wherein the diaphragm divides the interior space into a first cavity and a second cavity, wherein the diaphragm separates the first cavity from the second cavity in a fluid tight manner, and wherein the first cavity serves to hold the flowable medium; at least one channel which opens into the first cavity and through which the flowable medium can flow into the first cavity; and a dispensing opening, opening into the first cavity, for dispensing the flowable medium, wherein the rod has a sealing section, wherein the sealing section closes the dispensing opening in the first end position and is arranged at a distance from the dispensing opening in the second end position; wherein a pressure medium acting on the diaphragm is arranged in the second cavity, wherein the pressure medium is formed by a fluid or by an elastomer.

2. The device as claimed in claim 1, wherein the second cavity is sealed off in a fluid tight manner.

3. The device as claimed in claim 1, wherein the diaphragm is connected to the rod in a manner fixed relative to the rod.

4. The device as claimed in claim 3, wherein the diaphragm is held in the rod with a clamping action.

5. The device as claimed in claim 1, wherein the diaphragm is held with a clamping action between a housing wall section delimiting the first cavity and a housing wall section delimiting the second cavity.

6. The device as claimed in claim 1, wherein a barrier medium is arranged adjoining the diaphragm in the second cavity.

7. The device as claimed in claim 1, wherein a center line of a section of the at least one channel which opens into the first cavity intersects the diaphragm.

8. The device as claimed in claim 1, wherein the diaphragm comprises a thermoplastic.

9. The device as claimed in claim 1, wherein a material of the diaphragm is flexible in shape and inflexible in volume.

10. The device as claimed in claim 1, wherein, in the first end position of the rod, a section of the diaphragm which is arranged in the interior space and adjoins the housing and a section of the diaphragm which adjoins the rod are arranged in the same plane, and wherein the plane is formed perpendicularly to the axial direction.

11. The device as claimed in claim 1, wherein the diaphragm is designed as a flat diaphragm, a beaded diaphragm or a rolling diaphragm.

12. The device as claimed in claim 1, wherein the diaphragm has at least one section, which surrounds the rod and extends around the rod radially, and is arched in the axial direction.

13. A method for operating the device as claimed in claim 1, wherein the flowable medium is arranged in the first cavity, wherein the flowable medium acts on the diaphragm with a first pressure, wherein the pressure medium arranged in the second cavity acts on the diaphragm with a second pressure opposed to the first pressure, wherein the magnitude of the second pressure is 90% to 110% of the first pressure.

14. The method as claimed in claim 13, wherein the first pressure is 20 bar to 100 bar.

15. The device as claimed in claim 1, wherein the flowable medium is a hot melt adhesive.

16. The device as claimed in claim 8, wherein the diaphragm is composed of a thermoplastic.

17. The device as claimed in claim 9, wherein the material of the diaphragm comprises a thermoplastic.

18. The device as claimed in claim 12, wherein the diaphragm has two sections arched in opposite directions.

19. The method as claimed in claim 14, wherein the first pressure is 70 bar to 80 bar.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURE

(1) The invention is illustrated in the accompanying drawing FIGURE with reference to an exemplary embodiment without being restricted thereto.

(2) FIG. 1 shows a partial region of a device for dispensing a flowable medium in section, parallel to an axial direction.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENT OF THE INVENTION

(3) FIG. 1 shows a device 1 according to the invention for dispensing a flowable medium, in the present case for dispensing a hot melt adhesive. The device 1 has a head section 12 and a main body section 13. In this arrangement, the head section 12 is inserted into the main body section 13 and connected to the main body section 13, preferably being screwed to the latter at an end.

(4) The head section 12 and the main body section 13 form elements of a housing of the device 1, wherein this housing has an interior space with two cavities 2, 3.

(5) The device 1 has a flexible diaphragm 7, wherein a rod 5 mounted in the housing passes through the diaphragm 7 and wherein the diaphragm 7 is mounted in a sealed manner in the housing radially on the outside, in the present case being held with a clamping action between the head section 12 and the main body section 13, and is mounted in a sealed manner in the rod 5 radially on the inside, in the present case being held with a clamping action in the rod 5. The diaphragm 7 is connected to the rod 5 in a manner fixed relative to the rod 5, wherein in the present case the diaphragm 7 is held with a clamping action between a radial projection 16 of the rod 5 and a sleeve 14 connected to the rod 5. In the region of this clamping, the diaphragm 7 has a bead 17. The diaphragm 7 also has a bead 18 in its radially outer region, which is mounted with a clamping action between the head section 12 and the main body section 13.

(6) The diaphragm 7 is arranged in the interior space in such a way that it divides said space into a first cavity 2, which is rotationally symmetrical with respect to an axis passing through rod 5, and a second cavity 3, which is rotationally symmetrical with respect to the axis passing through rod 5, wherein the diaphragm 7 separates the first cavity 2 from the second cavity 3 in a fluid tight manner.

(7) The first cavity 2 serves to hold the flowable medium, wherein the device 1, in the present case the head section 12, has a channel 11 which opens into the first cavity 2 and through which the flowable medium can flow into the first cavity 2.

(8) The channel 11 is of angled configuration, wherein a center line 15 of a section of the channel 11 which opens into the first cavity 2 intersects the diaphragm 7. Thus, the inflowing flowable medium flows into the first cavity 2 in the direction of the second cavity 3.

(9) The head section 12 of the device 1 furthermore has a dispensing opening 4, which opens into the first cavity 2, for dispensing the flowable medium.

(10) For the purpose of closing the dispensing opening 4, the rod 5 has a sealing section 6. The rod 5 can be moved by means of an actuator (not illustrated) between a first end position and a second end position in an axial direction Z and vice versa, wherein the sealing section 6 closes the dispensing opening 4 in the first end position and is arranged at a distance from the dispensing opening 4 in the second end position. FIG. 1 shows the first end position in the left-hand half and the second end position in the right-hand half.

(11) The lift H, i.e. the axial distance between the first end position and the second end position of the rod 5, is preferably in a range of from 0.05 mm to 1 mm.

(12) The actuator can be a pneumatic cylinder, an electromechanical drive or an electropneumatic drive, for example.

(13) A pressure medium acting on the diaphragm 7 is arranged in the second cavity 3, wherein in the present case the pressure medium is a liquid.

(14) In the present case, the second cavity 3 is configured in such a way that the second cavity 3 is sealed off in a fluid tight manner during the operation of the device 1, and therefore no outflow or inflow of the fluid acting as the pressure medium is possible.

(15) The diaphragm 7 is held with a clamping action between a housing wall section 8 delimiting the first cavity 2 and a housing wall section 9 delimiting the second cavity 3, wherein wall section 8 is part of the head section 12 and wall section 9 is part of the main body section 13.

(16) In the first end position of the rod 5, a section of the diaphragm 7 which is arranged in the interior space and adjoins the housing and a section of the diaphragm 7 which adjoins the rod 5 are arranged in the same plane, wherein the plane is formed perpendicularly to the axial direction Z. This can be seen especially from the left-hand half of FIG. 1.

(17) The diaphragm 7 has precisely two sections 10, which surround the rod 5, extending around it radially, and are arched in the axial direction Z, wherein the two sections 10 are arched in opposite directions. In this case, the radially outermost arched section 10 is arched in the direction of the second cavity 3. In the sectional illustration shown in FIG. 1, an undulating cross section of the diaphragm 7 is thus obtained.

(18) By means of the device 1, it is possible to process flowable media which are under a high pressure, e.g. a pressure of 80 to 100 bar, and temperatures in a range of from 120° C. to 185° C., such as those which typically arise during the processing of hot melt adhesives, and yet to achieve a high switching frequency and a precise switching behavior and nevertheless a long life of the diaphragm 7.

(19) In addition to use for dispensing a hot melt adhesive, slight structural modifications also enable the device 1 to be used for control purposes. Slight structural modifications enable the device 1 to be used as a pressure control valve or as a restrictor, for example.

(20) When used as a restrictor or as a pressure control valve, the dispensing opening 4 remains permanently open in operation, and thus the rod 5 is outside the first end position. In this case, the axial distance from the first end position is either continuously controlled in order to limit or regulate a pressure, or the distance remains constant for a restrictor function.

(21) The device 1 can also be used to limit a pressure and can thus be a safety element, which is normally closed, the rod 5 thus being in the first end position, and very seldom performs the function of pressure limitation, in which the rod 5 transfers to a position which does not correspond to the first end position.