EP2138238A1 - Apparatus for intermittently dispensing fluids - Google Patents

Abstract

A method for rapid intermittent dispensing liquids, e.g. Adhesive stripes, has a pneumatic dispensing valve (10) in a dispensing head connected to liquid and compressed gas ducts. In order to achieve a rapid dispensing rate with a minimum of inertia the pneumatic valve is directly controlled by a solenoid valve (25) mounted close to the pneumatic valve, i.e. with a minimum of trapped pneumatic volume. The pneumatic valve operates against a return spring and the solenoid valve has a variable control, related to the applied voltage, to vary the dispensing rate.

Description

The invention relates to a device for the intermittent delivery of fluid media of the preamble of claim 1 corresponding type.

Such devices are used in the industry to apply, in sections, traces of fluid media, particularly adhesives, to a product displaced relative to a fluid medium dispenser. They comprise a dispensing module, which has a fluid channel opening out into a dispensing opening for the fluid medium. Further, a closure element is provided, which is pneumatically actuated between a dispensing opening opening and a dispensing opening occlusive position is displaced.

At one of the US 5407101 A Known, such device, the dispensing module is attached to a base body having a fluid channel for supplying the fluid medium and a compressed air channel for supplying compressed air to the dispensing module. The closure element is coupled in this device with a pneumatically actuated piston, which is arranged in a cylinder chamber such that a compressed air loading displaces the closure element against the action of a return spring in the dispensing opening opening position. The intermittent fluid delivery is effected by intermittently supplying compressed air to the compressed air channel. For this purpose, an external compressed air source with a likewise external valve arrangement is required, by means of which pressurized air is supplied to the compressed air channel in the frequency required for the intermittent delivery of the fluid medium.

Although such devices have proven themselves in industrial use, the maximum achievable with them operating frequencies of the closure element are limited. This is particularly disadvantageous because of the trend to ever greater relative speeds between the product and the device for the purpose of increasing productivity goes.

The invention is therefore based on the object, one from the US 5407101 A develop known device such that the actuation frequency of the closure element is increased.

This object is achieved by the reproduced in claim 1 device.

Characterized in that in the compressed air passage of the body an electrically actuated, a closure member exhibiting switching valve is turned on, which is adapted to control the dispensing module supplied compressed air so that the closure element in dependence of the applied operating voltage between the dispensing opening opening and closing the dispensing opening Position is displaced, the air volume, which must be filled to open the closure element of the dispensing module with compressed air, compared to the prior art substantially reduced. The result is that smaller amounts of air are required to build up the pneumatic pressure required for the actuation operation in the dispensing module, thereby reducing the amount of time needed to build up the pressure.

Furthermore, the steeper increase in pressure and also steeper pressure drop increase the speed of movement of the closure element, which leads to a sharper limitation of the portions of the fluid traces applied to a product.

Finally, the device of the invention over the prior art due to the integration of the switching valve in the body more compact outer dimensions, which facilitates the use of the device in industrial equipment, for example in gluing machines.

In a preferred embodiment of the device according to the invention, the switching valve comprises a coil for generating an electromagnetic Field and a movable means of the electromagnetic field armature, which is coupled to a closure member of the switching valve.

A particularly high efficiency is achieved when the coil is arranged around a portion of a pole and around a portion of the armature, as a result of which the coupling of the armature to the electromagnetic field is particularly effective.

The coupling can be further improved if the switching valve comprises a flux guide element which distributes the flow between the pole and the armature such that the closure element of the switching valve is displaced into the open position.

The flux guide element may have a non-circular cross-section. It is particularly preferred if it has a rectangular cross-section, since it can then be configured adapted to the outer contour of the two mutually parallel, planar sides having basic body.

Particularly preferred is a variant of the device according to the invention, in which the switching valve comprises means which generate restoring forces, which displace the closure member in the closed position when no actuation voltage is applied. This measure prevents uncontrolled leaking fluid from the discharge opening when the operating voltage collapses, for example due to a technical defect.

The masses moved during the actuation of the switching valve can be reduced if the switching valve is designed in such a way that the restoring forces are generated by the compressed air. However, it is preferred to effect the restoring forces by means of a return spring.

Particularly preferred is a development of the device according to the invention, in which the base body comprises a heating element. The device is then also suitable to hot melt adhesive, which unfolds its adhesive effect during solidification, apply, as it is commonly used industrially.

The maximum operating temperature of the device according to the invention, under which a fluid medium can be discharged, is limited by the heat resistance of commercially available coils. An increase in the maximum operating temperature is possible, are provided in the means for cooling the coil. However, it is particularly preferred if the coil comprises a winding of a coil provided with a heat-resistant insulation coil wire, as this can be dispensed with complex means for cooling the coil.

The closure element of the dispensing module is preferably coupled to a pneumatically operated differential piston in which the restoring forces are generated by a permanently applied pneumatic pressure. The actuating forces for displacing the closure element to open the discharge opening are effected by the fact that upon actuation of the switching valve, the pneumatic pressure is directed to a surface of the differential piston, which is larger than the surface causing the restoring forces and aligned so that the actuating forces counteract the restoring forces.

To increase the reliability of the device according to the invention, an auxiliary spring acting on the differential piston is preferably additionally provided, which displaces the closure element in the closed position at non-applied pneumatic pressure. This avoids that uncontrolled fluid escapes from the discharge opening when the pneumatic pressure should collapse.

Fig. 1

das Ausführungsbeispiel in einer teilgeschnittenen Seitenansicht;

Fig. 2

- ausschnittsweise - das Verschlussorgan und den Anker des Schaltventils in einer vergrößerten Detailansicht im geschlossenen Zustand sowie

Fig. 3

eine Fig. 2 entsprechende Darstellung im geöffneten Zustand.

In the drawing - is shown schematically - an embodiment of a device according to the invention. Show it:

Fig. 1

the embodiment in a partially sectioned side view;

Fig. 2

- Partial - the closure member and the armature of the switching valve in an enlarged detail view in the closed state and

Fig. 3

a Fig. 2 corresponding representation in the open state.

In the Fig. 1 The device 100, as a whole, comprises a dispensing module 1, which has a housing 2 with a rectangular cross-section. In the housing 2, a cylinder chamber 3 is formed, which has the shape of a stepped bore.

In the cylinder chamber 3, a differential piston 4 is arranged with two piston surfaces of different diameters such that the piston surface 5 closes tightly with the smaller diameter with the cylinder wall of the part 6 of the cylinder chamber 3 with the smaller diameter. The piston surface 7 closes tightly with the part 8 of the cylinder chamber 3, which has the larger diameter.

Between the piston part 7 forming piston part and the edge 9 formed on the basis of the stepped bore, a compression spring 4 'is supported.

The differential piston 4 is connected to a closing element 10 extending vertically from the piston surface 7, which passes through a guide bore 11, in which it is guided in a sliding manner, and extends through a fluid channel 12 as far as a discharge opening 13, into which the fluid channel 12 empties.

The closure element 10 can be displaced by means of the differential piston 4 between a position which opens the dispensing opening and a position which closes the dispensing opening, as will be described below.

In the upper part 6 of the cylinder chamber 3, a first compressed air channel 14 opens, the other end to a side wall 15 of the dispensing module 1 in a Opening 16 exits. In the lower part 8 of the cylinder chamber 3, a second compressed air channel 17 opens, the other end also emerges from the side wall 15 in an opening 18. Also, the fluid channel 12 is arranged in the housing 2 such that it opens into an opening 19 in the side wall 15.

The dispensing module 1 is attached with its side wall 15 on the end wall 20 of a base body 21 by a not visible in the drawing screw. The main body comprises a fluid channel 22, the first end of which opens into a connection 23 for a fluid supply hose and the second end of which opens into an opening 19 which is congruent to the opening 19 in the dispensing module 1.

Furthermore, the main body 1 comprises electrical connection means 26 for operating a heating device 24 of known type and an electrically actuatable switching valve 25 which is accommodated in the base body 21.

The switching valve 25 comprises a coil 27 for generating an electromagnetic field and a displaceable by means of the electromagnetic field armature 28 which is coupled to a closure member 29 of the switching valve 25.

The switching valve further includes a pole 30 protruding into the interior of the coil from one end. The armature 28 is arranged such that a portion thereof projects from the other end into the coil 27.

Further, the switching valve 25 comprises a flux guide member 31 surrounding the coil and which distributes the flow between the pole 30 and the armature 28 so that the armature 28 is attracted by the pole 30.

The flux guide element 31 has a rectangular cross section and an outer contour, which is adapted to the Außenkontor of the main body 21, that the main body 21 and the flux guide element 31 form flat, rugged outer surfaces.

In the main body 21, a central compressed air passage 32 is further arranged, one end of which opens into connecting means 33 for connecting a compressed air supply line. The compressed air channel 32 branches in the main body 21 in a passage 34 which is connected via an opening 16 'with the first compressed air channel 14, and in a channel 35 which can be selectively connected via the closure member 29 with the compressed air channel 32.

In the Fig. 1 and 2 the device according to the invention is shown in a state in which it is located when no operating voltage is applied to the coil 27 and the compressed air channel 32 is acted upon with compressed air. The closing member 29 shuts off the channel 35 from the compressed air channel 32 by abutting against a lower sealing ring 29 "of the main body 21 so that pneumatic pressure is applied to the piston surface 5 via the passage 34 and pushes the differential piston 4 downwards the closure element 10 is also pressed down and closes the discharge opening 13th

When the armature 28 is displaced upwardly by applying an electrical actuating voltage to the coil 27 in the drawing in the open state, as shown in Fig. 3 is shown, the closure element 29 is also displaced upward due to the pneumatic pressure until it rests against an upper sealing ring 29 'of the main body 21. The lower sealing ring 29 "is released, and the pneumatic pressure then also acts on the piston surface 7 via the channel 35. Since this is larger than the piston surface 5, the force acting on the piston surface 7 due to the pneumatic pressure is greater than that on the piston surface Piston surfaces 5. The differential piston 4 is displaced upwards together with the closure element 10 according to the drawing, whereby the discharge opening 13 is released It is understood that the pneumatic pressure is chosen such that the pressure acting on the piston surfaces 5, 7 Pressure creates a resultant force which is capable of overcoming the force exerted by the compression spring 4 '.

If the operating voltage is switched off, the armature 28 moves with the closure member 29 in the in the Fig. 1 and 2 shown position due the restoring forces acting on it, which are generated by a return spring 36. The return spring 36 is arranged in a provided in the anchor blind hole 37 and rests with its bottom according to the drawing at the bottom 38 of the blind hole 37 from. The upper end 39 of the return spring 36 is supported on the lower end face 40 of the pole 30 from. The upper sealing ring 29 'is released. The pressure in the chamber 3 'degrades, since by releasing the sealing ring 29', a connection of the channel 35 is made with an annular space 41 surrounding the armature, which opens into an outlet 42.

The displacement of the differential piston 4 can thus take place exclusively under the action of the applied pneumatic pressure by actuation of the switching valve 25. The compression spring 4 'is nevertheless provided so that in the event of a collapse of the pneumatic pressure, the differential piston 4 is displaced to its lower position and the discharge opening 13 is closed by the closure element 10 so as to prevent an uncontrolled escape of the fluid medium to be dispensed.

LIST OF REFERENCE NUMBERS

100

contraption

1

delivery module

2

casing

3

cylinder chamber

4

differential piston

4 '

compression spring

5

piston area

6

part

7

piston area

8th

part

9

edge

10

closure element

11

guide bore

12

fluid channel

13

discharge opening

14

first compressed air duct

15

sidewall

16, 16 '

opening

17

second compressed air channel

18

opening

19, 19 '

opening

20

end wall

21

body

22

fluid channel

23

connection

24

heater

25

switching valve

26

electrical connection means

27

Kitchen sink

28

anchor

29

closure member

29 ', 29 "

seals

30

pole

31

Flux guide

32

Compressed air duct

33

connection means

34

Through channel

35

channel

36

Return spring

37

Blind hole

38

ground

39

The End

40

front

41

annulus

42

outlet

Claims (12)

Device for the intermittent delivery of fluid media such as adhesives,
with a dispensing module (1), which comprises a fluid channel (12) opening into a dispensing opening (13),
with a closure element (10) which is pneumatically actuated between a position opening the dispensing opening (13) and a position closing the dispensing opening (13),
and a base body (21) to which the dispensing module (1) is fastened, which has a fluid channel (22) for the supply of the fluid medium and a compressed air channel (32) for the supply of compressed air to the dispensing module (1),
characterized,
in that the base body (21) comprises an electrically actuable, a closure member (29) exhibiting switching valve (25) which is turned on in the compressed air channel (32) and which is adapted to control the compressed air supplied to the dispensing module (1) so that the closure element (10) depending on the applied operating voltage between the discharge opening opening and the discharge opening closing position is displaced. Device according to claim 1,
characterized,
in that the switching valve (25) comprises a coil (27) for generating an electromagnetic field and an armature (28) displaceable by means of the electromagnetic field, which is coupled to the closure member (29) of the switching valve (25). Device according to claim 2,
characterized,
in that the coil (27) is arranged around a portion of a pole (30) and around a portion of the armature (28). Device according to claim 3,
characterized,
in that the switching valve (25) comprises a flow guide element (31) which distributes the flow between the pole (30) and the armature (28) so that the closure member (29) of the switching valve (25) is displaced to the open position. Device according to claim 4,
characterized,
that the flow guide element (31) has a non-circular cross-section. Device according to claim 5,
characterized,
that the flow guide element (31) has a rectangular cross-section. Device according to one of claims 1 to 6,
characterized,
in that the switching valve (25) comprises means which generate restoring forces which displace the closure member (29) into the closed position when no actuating voltage is applied to the coil (27). Device according to claim 7,
characterized,
that the switching valve (25) comprises a return spring (36). Device according to one of claims 1 to 8,
characterized,
that the basic body (21) comprises a heater (24). Device according to one of claims 1 to 9,
characterized,
that the coil (27) comprises a winding of a sleeve provided with a heat resistant insulation coil wire. Device according to one of claims 1 to 10,
characterized,
in that the closure element (10) is coupled to a pneumatically actuated differential piston (4). Device according to claim 11,
characterized,
that an auxiliary spring is provided, acting on the differential piston (4) such that when not touching pneumatic pressure, the closure element (10) is moved to the closed position.

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