AU649791B2

AU649791B2 - Delivery device

Info

Publication number: AU649791B2
Application number: AU12828/92A
Authority: AU
Inventors: Franz Zimmerhackel
Original assignee: Deutsche Prazisions Ventil GmbH
Current assignee: Deutsche Prazisions Ventil GmbH
Priority date: 1991-09-16
Filing date: 1992-03-11
Publication date: 1994-06-02
Anticipated expiration: 2012-03-11
Also published as: AU1282892A; HUT62525A; NZ244350A; JPH05213381A; CA2062863A1; HU9201039D0; BR9200968A; JPH0662184B2; KR930005680A; EP0532822A1; CN1074991A; DE4130728A1; MX9201268A; ZA922043B

Description

649791

AUSTRALIA

Patents Act 1990 DEUTSCHE PRAZISIONS-VENTIL GMBH

ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT Invention Title: o s DELIVERY DEVICE o o The following st tement is a full description of this invention including the best method of performing it known to us:- 14 Delivery device The invention concerns a delivery device for spray cans filled with a product which is capable of flow and which is under gas pressure, having a product path which is closable by a delivery valve and has a throttle nozzle arrangement which on its inlet side has at least one inlet duct which is arranged substantially in a plane extending perpendicularly to the axial direction, and on its outlet side a substantially axially extending outlet duct into which the inlet duct opens substantially tangentially.

A delivery device of that kind is known from EP 0 420 538 Al. In that design the throttle nozzle arrangement simultaneously forms a delivery nozzle through which the product issues from the spray can into .the environment, and is sprayed or atomised. The known delivery device is used in particular where the product and the propellant gas are admittedly disposed in the interior of the spray can in a ccmnon space, oo: 15 but essentially separately from each other, that is to say, the gas is not dissolved in the product at all, or is dissolved therein only to a negligibly small degree. In such cases the gas pressure decreases with increasing emptying of the spray can. However, with decreasing pressure, I the volume flow of the delivered product normally also decreases, and the size of the droplets of the sprayed product alters. That disadvantageous phenomenon can be attenuated by means of the ]mown throttle nozzle arrangement. The volume flow and the droplet size remain substantially constant, even if the pressure drops with increasing emptying of the spray can.

In the known delivery device, the throttle nozzle arrangement, as the last throttle means in the product path, produces the strongest throttling action in regard to the issuing product. Its flow crosssection is smaller than that of the preceding throttle means.

Correspondingly there is also the greatest pressure drop across the delivery nozzle. That makes fine adjustment of the delivery volume flow a very difficult matter. If the throttle resistance is selected to be too great, it is no longer possible to ensure effective spraying of the product. If it is too small, it is no longer possible to guarantee that the volume flow will be constant. In addition, particularly when dealing with resinating or adhesive products which harden in conjunction with constituents in the air, for example oxygen, it is extremely difficult to continue operation of the known delivery device with the same properties, after an interruption in the delivery of the product. In general the throttle nozzle arrangement becomes clogged.

The invention is based on the problem of providing a delivery device which is simple to produce and which gives better controllability in respect of the delivery volume flow.

this specification, ir accordance with the invention that probl~n is solved in that the throttle nozzle arrangement is arrar in the 20 product path upstream of the delivery valve in the dire ion of flow.

t*p That arrangement does not only provide t the throttle nozzle arrangement is substantially shut away fr e ambient atmosphere and constituents in the ambient atmosphere annot therefore be involved in any chemical processes with the product, which could result in clogging of the throttle nozzle arr ement. The design also provides that the volume flow can be con t6lled in a very much better fashion. The initial product flow whic n the known case is about 0.55 g/s can be reduced to about 0.3 with the delivery device according to the invention, and that yaue can be maintained, with slight changes, over the entire 2a Accordingly, the present invention provides a delivery device for spray cans filled with a product which is capable of flow and which is under gas pressure, having a product path which is closable by a delivery valve and has a throttle nozzle arrangement which on its inlet side has at least one inlet duct which is arranged substantially in a plane extending perpendicularly to an axial direction, and on its outlet side a substantially axially extending outlet duct into which the inlet duct opens substantially tangentially, the throttle nozzle arrangement being arranged in the product path upstream of the delivery valve in the direction of flow, the inlet duct has a reduction in cross-section in the region of its mouth opening into the outlet duct and the cross-section 40: 15 of the inlet duct continuously decreasing towards the S.outlet duct.

That arrangement does not only provide that the eooee S"throttle nozzle arrangement is substantially shut away from the ambient atmosphere and constituents in the 20 ambient atmosphere cannot therefore be involved in any chemical processes with the product, which could result in clogging of the throttle nozzle arrangement. The design alsn provides that the volume flow can be controlled in a 0eo0 very much better fashion. The initial product flow which 25 in the known case is about 0.55 g/s can be reduced to 0 about 0.3 g/s with the delivery device according to the invention, and that value can be maintained, with slight changes, over the entire procedure of emptying the spray can. Furthermore, production of a

RA

9-T*Ii \CAj delivery device of that kind is substantially easier. The throttle nozzle arrangement can be fitted in a quasi self-holding fashion into the product path.

In a preferred embodiment an expansion space is provided between the throttle nozzle arrangement and the delivery valve. The flow rate of the product which flows into that expansion space is substantially reduced by the throttle nozzle arrangement in which the product has not only been throttled but also swirled around by virtue of the inlet ducts opening tangentially into the outlet duct, wherein, by virtue of the specific configuration of the throttle nozzle arrangement, the flow rate is substantially less strongly dependent on the pressure difference across the throttle nozzle arrangement, than in the case of simple throttles. Expansion in the expansion chamber is followed by a fresh throttling action in the delivery valve. A further Expansion effect and subsequently a further throttling action by a dist large nozzle is optionally possible. It has been found that, when there is the .9 ~possibility of expansion in that way, downstream of the throttle nozzle arrangement, the volume flow can be made independent of the pressure in the spray can, to a greater degree than was previously the case. The discharge flow rate of the product, that is to say the volume flow, is determined primarily by the structure and the dimensioning of the throttle nozzle arrangement.

In this connection it is preferred that the size of th'v expansion "space alters, in particular decreases, when the delivery valve is actuated, That can provide for a further and highly sensitive control of the flow of product. The delivery valve can generally be opened to a greater or lesser degree, thereby giving different pressure conditions in the expansion chamber, which are also dependent on the volume flow of the issuing product. The changes in such pressure conditions may be :ee f partially compensated by the variation in the size of the expansion space. Total compensation is of course not desirable as the fact that 4 the delivery valve is opened to a different degree means that there is also a wish to achieve a product discharge rate of different magnitude.

With the inlet duct having a reduction in cross-section in the region of its mouth opening into the outlet duct the invention results in acceleration of the product flowing through the throttle nozzle arrangement, precisely at the moment at which the product flows into the outlet duct. The tangential inflow causes a swirling turbulence in the outlet duct. The greater the inflow rate, the more intensive can the swirling turbulence effect be.

It is to be assumed that the cc ~tancy of the volume o flow is heavily dependent on the strength of the swirling t 15 turbulence effect and is improved, the greater the swirling turbulence effect. Accordingly, a reduction in the cross-section further provides that the voli ie flow can be kept constant.

In addition, by virtue of the cross-section of the S 20 inlet duct continuously decreasing towards the outlet see,, S.,1 duct the product is relatively uniformly accelerated.

to The best results can be achieved if there are a plurality of, in particular two or three, rotationally symmetrically distributed inlet ducts. That arrangement e.25 ensures on the one hand that a sufficient amount of the *see product can pass into the outlet duct. On the other hand, that arrangement can ensure that that amount is subjected to a swirling turbulence effect in a highly regular fashion.

Preferably the throttle nozzle arrangement has an insert member which is fitted into the product path and which has an outlet duct passing therethrough and an inlet duct which is at least partially open to the inlet side and which bears against an abutment in the product path, the abutment covering over the outlet duct on the inlet c 4a side and exposing a part of the inlet duct. The throttle nozzle arrangexuent is 0* a a a a. a a a a.

a.

a a. a.

a.

a a a. a.

a a a a a.

a a a. a a a therefore formed substantially by two parts, namely on the one hand the insert member and on the other hand the abutment. The abutment does not serve just as a mechanical support for the insert member. It also ,nsures that the product cannot flow freely through the outlet duct. On the contrary, it forces the product to flow through the inlet duct or ducts which it leaves partially free, and tangentially into the outlet duct in order there to be involved in a swirl turbulence effect.

Manufacture of the delivery device can be very simple, by virtue of the separate insert member.

It is also preferred that, at least in the region of the insert member, the product duct is of a circular cross-section or a crosssection in the form of a regular polygon and the cross-section of the insert member is adapted to the cross-section of the product duct. The insert member can accoriingly be inserted in practically any angular position. There is no need to pay attention to specific directions of insertion.

Preferably the insert member has a disc which contains the nlet duct and the outlet duct and which is arranged substantially perpendicularly to the axis of the product duct within a hollow e.

cylinder. The insert member is therefore in the form of a H in cross- S section, wherein the cross bar of the H represents the disc and the four legs of the H represent the wall of the hollow cylinder. By virtue of that configuration, it is possible to achieve a good sealing action for S"the insert member in the product duct without the need to take expensive measures. The product is forced to flow through the throttle nozzle arrangement without being able to flow past the side thereof.

Manufacture of an insert member of that kind is a very simple matter.

That is the case to a particular degree when the disc is defined by two substantially parallel flat surfaces.

Preferably the hollow cylinder enlarges in a conical configuration at the outlet side. That does not just have positive effects on the flow characteristics of the product on issuing from the outlet duct, the conicity also permits the return spring to be securely guided laterally and centered in relation to the insert member.

It is also preferred that on the outlet side the disc has grooves or bar portions which extend from the outlet duct outwardly, in particular radially, and communicate with axial grooves or axial bar portions provided in the inside wall of the hollow cylinder. Even if the actuating member of the outlet valve is depressed to such a degree that it comes to bear against the disc, a flow of product is ensured, a suitable flow path being formed by the grooves on the disc and the axial grooves in the inside wall of the cylinder, or the intermediate spaces between the bar portions on the disc or the axial bar portions on the inside wall of the hollow cylinder. When using axial bar portions, it is sufficient if the diametral space defined by the axial bar portions is enlarged in a conical configuration.

Advantageously the wall thickness of the hollow cylinder is substantially constant in the region of the axial grooves or in the region between the axial bar portions. The depth of the axial grooves or the thickness of the axial bar portions therefore decreases in the 20 direction towards the outlet side of the insert member. That panmits a 'progressive transition in respect of the outwardly flowing product, from the axial grooves into the expansion space. Preferably, for that purpose, at the end towards tha outlet the hollow cylinder is of a wall thickness which corresponds to that in the region of the axial grooves or in the region between the axial bar portions. In other words, directly at the edge of the hollow cylinder there is a smooth surface over which the product can flow into the expansion space.

Preferably the length of the hollow cylinder is at least equal to I its radius. That ensures sufficient stability for the hollow cy' Lnder in 30 the product duct. Tilting or twisting of the insert member upon assembly 9 is substantially eliminated.

A further advantage is that the outlet duct has a portion of smaller diameter, into which the inlet duct opens, and a portion of larger diameter. E, ying the lengths of those two portions, it is possible to provide for relatively accurate adjustment of the magnitude of the volume flow. The remaining shape of the insert member does not have to be altered. As a result manufacture is very simple. It is only necessary to replace parts of an injection mould, but there is no need to renew the entire mould.

The invention is described hereinafter by means of a preferred embodiment with reference to the drawings in which: Figure 1 is a view in cross-section through a delivery device, Figure 2 is a view in cross-section on an enlarged scale through an insert member, Figure 3 is a view of the insert member from below, Figure 4 is a view of the insert member from above, and Figure 5 is a view of an alternative insert member from above.

A delivery device 1 is disposed in a top 2 of a spray can (not shown). It has a housing 3 in which a valve member 4 of a delivery valve S* 20 5 is arranged displaceably against the force of a return spring 6. The delivery valve 5 closes off a product path 14 or opens it, when actuated. The valve rnrmber 4 has one or more transverse ducts 7. When the return spring 6 has moved the valve member 4 into the illustrated rest position 8, the transverse ducts 7 are closed by a sealing means.

25 When the valve member 4 has been pressed into the housing 3 against the force of the return spring 6, the transverse ducts 7 open into an r* annular space 9 which surrounds the valve housing 4 within the housing 3. The annular space 9 opens into an expanlion space 10 which is delimited on the opposite side by a throttle nozle arrangement 11. The throttle nozzle arrangement has an insert member 12 which bears against an abutment 13 which is provided in the product duct 14 and is connected to the wall of the product duct 14 for example by way of one or more bar portions 15. Arranged at the end of the product duct 14 at the inlet side is a riser pipe 16 by way of which a product can be supplied from the spray can. Also provided in the product duct 14 is a peripherally extending projection 29, behind which the insert member 12 latches. The projection 29 may also be interrupted. The insert member is clamped in position between the projection 29 and the abutment 13.

The product in the spray can is under the pressure of a gas which is not dissolved in the product. As the spray can is increasingly emptied, the space available for that gas becomes progressively greater.

Consequently the pressure of the gas decreases. The throttle' nozzle arrangement 11 disposed in the product duct 14 provides, in particular in conjunction with the expansion space 10 that, in spite of the reduction in the gas pressure in the container, the volume flow of the product can be kept at least approximately constant, that is to say, the delivery 1-ate of the product is substantially independent of the condition of emptying of the can.

The insert member 12 of the throttle nozzle arrangement 11 is in the form of a H in cross-section, with the cross bar of the H being S. 20 formed by a disc 17 which is disposed within a hollow cylinder 18. The •disc is delimited by two flat surfaces 19, 20 which extend substantially parallel to each other. The hollow cylinder 18 is enlarged in a conical configuration at the outlet side, that is to say its wall thickness decreases, starting fran the disc 17 towards the outlet side, in a 25 direction towards the delivery valve 5. At its end towards the inlet side the hollow cylinder 18 has a rounded configuration 21 by way of e00 which the outside wall of the hollow cylinder 18 blends into its end.

*get The hollow cylinder 18 is of greater wall thickness at its inlet end than at its outlet end. The length of the hollow cylinder 18 corresponds e0•o• at least to its radius. In general however it is larger. It may certainly also be in the region of twice the radius.

An outlet duct 22 is disposed in the disc 17 of the insert member 12. The outlet duct 22 passes completely through the disc 17. The outlet duct has a portion 22a of a smaller diameter and a portion 22b of a larger diameter, as well as a swirl space 25 which is disposed upstream of the portion 22a. Opening into the swirl space 25 of the outlet duct 22 are three rotationally symetrically arranged inlet ducts 23 which are disposed on the inlet side of the disc 17 of the insert member 12, that is to say the side which is remote from the delivery valve 5. The inlet ducts 23 are open towards the inlet side, that is to say they are of a groove-like configuration in the surface 20. They extend from the wall of the hollow cylinder 18 to the outlet duct 22, being of 'such a configuration that they open tangentially into the outlet duct 22. A flow of product which is passed through the inlet ducts 23 is therefore forced to experience swirl turbulence in the outlet duct 22, that is to say in the swirl space 25. In that case, a flow which has a substantial component in the azimuthal direction obtains in the outlet duct 22. That component may be greater than the flow component in the axial direction.

At their ends towards the outl"t duct 22, the inlet ducts 23 have a cross-sectional reduction 24 which is formed by the cross-section of the 20 inlet ducts 23 continuously decreasing in a direction towards the outlet S• duct 22. The inlet ducts 23 do not extend precisely radially but extend from the wall of the hollow cylinder 18 towards a point which is displaced outwardly by a predetermined amount relative to the central point of the disc 17.

On the outlet side, radially extending bar portions 26 or projections are arranged on the surface 19 of the disc 17 and continue in axial bar portions 27 on the wall of the hollow cylinder 18. An intermediate space remains free between the bar portions 26. The wall thickness of the hollow cylinder 18 is constant in the region between 30 the axial bar portions 27. The wall thickness of the axial bar portions 27 continuously decreases from the disc 17 to the end which is towards the outlet, until, at the end of the insert member 12, it is of a thickness which corresponds to that in the region between the axial bar portions 27.

In an alternative configuration (see Figure arranged at the outlet side in the surface 19' of the disc 17 are radially extending r( ooves 26' which open into axial grooves 27' in the wall of the hollow cylinder 18'. The wall thickness of the hollow cylinder .18' is constant in the region of the axial grooves 27'. Outside the axial grooves 27, the wall thickness continuously decreases from the disc 17 towards the end which is towards the outlet, until at the end towards the outlet of the insert member 12 it attains a thickness which corresponds to the constant thickness in the region of the axial grooves 27'.

The grooves or the intermediate spaces between the bar portions guarantee a product path, even if the valve member 4 is pressed in to a very great extent.

The mode of operation of the delivery device 1 and in particular the co-operation between the insert member 12 and the abutment 13 will S' be apparent from Figure 1. The insert member is pressed against the 20 abutment 13 by means of the projection 29. That causes the direct path through the outlet duct 22 to be blocked. Product which is conveyed through the riser pipe and the product duct 14 towards the delivery valve 5 must pass into an annular space 28 which is formed between the abutment 13 and the end of the hollow cylinder 18, which is towards the 25 inlet. From there the product is forced into the inlet ducts 23 and conveyed towards the cutlet duct 22. As the cross-section of the inlet ducts 23 continuously decreases, the product is accelerated. It passes at a higher speed into the outlet duct 22 or the swirl space 25. From there it flows through the outlet duct 22 into the expansion space where it can expand again. From the expansion space 10 it flows through the annular spa&o 9 and the transverse duct 7 to the outlet or to a delivery nozzle.

The expansion space 10 is reduced in size when the valve member 4 is pressed down, that is to say when the delivery valve 5 opens. The greater the degree to which the valve member 4 is pressed down, that is to say the greater the degree of opening of the delivery valve 5, the greater also is the extent of the reduction in size of the expansion space 10. By virtue of suitable matching as between opening of the transverse ducts 7 and the expansion space 10, it is possible to provide for partial compensation, to the effect that the volume flow increases to a smaller degree than would normally be expected upon actuation of the valve member 4. In that way, it is possible to provide for very fine and sensitive control of the volume flow upon actuation of the valve 4.

Even if the valve member 4 is movod towards the insert member 12 against the force of the return spring 6 to such an extent that it comes to bear against the insert member, the grooves 26' or the bar portions 26 guarantee a flow path for the fluid. The axial grooves 27' or the axial bar portions 27 provide on the one hand for an interruption in the smooth surface of the hollow cylinder 18, whereby the component of the flow of the product in the a2imuthal direction is reduced after leaving the outlet duct 22, while on the other hand the hollow cylinder 18, at *0 20 its end towards the outlet, has a smooth edge so that no additional turbulence phenomena occur on leaving the hollow cylinder 18.

The conicity of the hollow cylinder 18 or the axial bar portions 27 provides for centering of the return spring 6 in the insert member 12.

As the insert member 12, just like the product duct 14, is of a round cross-section, the insert member 12 can be pushed into the product duct 14 in any angular position. Assembly is further facilitated by the e* rounded portion 21.

The throttle, property of the throttle nozzle arrangement 11 can be controlled with very simple means, by way of the two portions 22a and 30 22b of the outlet duct 22. If the poion 22a is 30 22b of the outlet duct 22. If the smaller-diameter portion 22a is increased in length, the flow resistance is increased. If on the other hand it is reduced, the flow resistance is reduced. Nothing about the remainder of the shape of the insert member 12 has to be changed.

Manufacture of the delivery device 1 is very simple. It only differs frcm manufacture of a conventional delivery device in that an insert member 12 has to be additionally inserted into the product duct 14. That additional working step is very simple however, due to the rounded portion 21 and the round cross-section of the insert member 12, so that it has practically no adverse effect on production.

00 4.

4 4 *.4.4

Claims

2. A delivery device according to claim 1 characterised r in that an expansion space is provided between the throttle nozzle arrangement and the delivery valve. 20 3. A delivery device according to claim 2 characterised in that the size of the expansion space alters, in particular decreases, when the delivery valve is actuated.
4. A delivery device according to any one of claims 1 to oo 3 characterised in that there are provided a plurality of 25 and in particular two or three rotationally symmetrically distributed inlet ducts. A delivery device according to any one of claims 1 to 6 characterised in that the throttle nozzle arrangement has an insert member which is fitted into the product path and which has an outlet duct passing therethrough and an inlet duct which is at least partially open towards the inlet side and which bears against an abutment in the product path, the abutment covering over the outlet duct on the inlet side and exposing a part of the inlet duct.
6. A delivery device according to claim 5 characterised 14 in that, at least in the region of the insert member, the product duct is of a circular cross-section or a cross-section in the form of a regular polygon and the cross-section of the insert member is adapted to the cross-section of the product duct.
7. A delivery device according to claim 6 characterised in that the insert member has a disc which contains the inlet duct and the outlet duct and which is arranged substantially perpendicularly to the axis of the product duct within a hollow cylinder.
8. A delivery device according to claim 7 characterised in that the disc is defined by two substantially parallel flat surfaces. 1: 9. A delivery device according to claim 7 or claim 8 S15 characterised in that the hollow cylinder enlarges in a conical configuration at the outlet side. S"10. a delivery device according to any one of claims 7 to S' 9 characterised in that on the outlet side the disc has grooves or bar portions which extend from the outlet duct outwardly, in particular radially, and communicate with axial grooves or axial bar portions provided in the inside 6*wall of the hollow cylinder.
11. A delivery device according to claim 10 characterised eel• in that the wall thickness of the hollow cylinder is 25 sk stantially constant in the region of the axial grooves or in the region of the intermediate space between the axial bar portions.
12. A delivery device according to claim 11 characterised in that at the end towards the outlet the hollow cylinder is of a wall thickness which corresponds to that in the region of the axial grooves or in the region of the intermediate space between the axial bar portions.
13. A delivery device according to any one of claims 9 to 12 characterised in that the length of the hollow cylinder is at least equal to its radius. riii 15
14. A delivery device according to any one of claims 1 to 13 characterised in that the outlet duct has a portion of smaller diameter, into which t;he inlet duct opens, and a portion of larger diameter.
15. A delivery device substantially as hereinbefore described with reference to the accompanying drawings. DATED this 4th day of March 1994 DEUTSCHE PRAZISIONS-VENTIL GmbH Patent AttorneyG for the Applicant: F.B. RICE CO. S. S S S S* *5 5 5* SO S *5 5 9 5 S *5 S. S S 55 S S SOS SSS 5555 S S S 55 55 5 S S 5.55 S S S'S. 55 S S 59 9 5* .5.5 S 9 9555 4>' L ABSTRACT There is provided a delivery device for spray cans filled with a product which is capable of flow and which is under gas pressure, having a product path (14) which is closable by a delivery valve and has a throttle nozzle arrangement which on its inlet side has at least one inlet duct (23) which is arranged substantially in a plane extending perpendicularly to the axial direction, and on its outlet side a substantially axially extending outlet duct (22) into which the inlet ductopens substantially tangentially. The delivery volume flow of the product is to be kept substantially consteit with a delivery device of that kind, irrespective of the degree of filling of the spray can which is put under pressure by a gas which is practically not dissolved in the product, and blockage of the product flow path is to be prevented, while involving a simple structure. For that purpose the throttle nozzle arrangement (11) is *o i arranged in the product path (14) upstream of the delivery valve in the direction of flow. e S. Figure 1. S. 0O 0 *0 0 OO* 0