EP0464122B1

EP0464122B1 - Spray head for a spray can

Info

Publication number: EP0464122B1
Application number: EP19900905695
Authority: EP
Inventors: Edgar Ivo Maria Van Der Heijden
Original assignee: Airspray International BV
Current assignee: Airspray International BV
Priority date: 1989-03-23
Filing date: 1990-03-20
Publication date: 1992-12-30
Anticipated expiration: 2010-03-20
Also published as: JPH04504244A; WO1990011237A1; EP0464122A1; NL8900729A; AU5351690A

Abstract

A spray head for a spray can, comprising a hollow stem having a bore which is adapted to be brought into communication with the liquid space of the spray can, and which on the other hand, terminates near a spray nozzle having an exit aperture, so as to force liquid driven into said bore by the outward pressure of the spray can through said aperture for being sprayed; according to the invention, in the flow path (3, 4, 6) of the liquid, a passage operating as a jet pump (7) driven by the liquid flow pressed outwards is included, the suction side (10) of which communicates with the ambient air.

Description

The invention relates to a spray head for a spray can, comprising a hollow stem having a bore which is adapted to be brought into communication with the liquid space of the spray can, and which on the other hand, terminates near a spray nozzle having an exit aperture, so as to force liquid driven into said bore by the outward pressure of the spray can through said aperture for being sprayed.
In the known spray cans using a driving agent contained in the spray can as a liquid which strongly evaporates at the ambient temperature and mixes with the liquid to be sprayed, the droplets of the sprayed liquid formed in the nozzle will still contain driving agent which immediately evaporate, so that the droplets will be reduced which enhances the formation of a fine mist.
With some liquids coalescence of droplets occurs in the sprayed jet or large drops are formed by other causes which will lead to the formation of a coherent layer on a sprayed surface which is undesired. In order to avoid this, it is known to mix in a mixing chamber an additional amount of the driving medium with the liquid pressed towards the nozzle which will lead to a reduction of the droplet size. This requires, of course, providing a larger quantity of driving agent in the spray can, which is unfavourable, and discharging noxious driving agents into the ambient air is highly undesirable.
In order to avoid the use of such driving agents it is known to use compressed air as the driving agent, which, for instance, is obtained by means of a protecting cap for the spray head operating as a pump. Since the air dissolved in the liquid to be sprayed will hardly evaporate from the liquid droplets at or after spraying, larger drops will sooner occur in such spray cans than when using an evaporating driving agent, so that when using air the admixture of air will nearly always be required. This leads, however, to a larger air consumption so that air is to pumped in very often which can be onerous for the user.
It is an object of the invention to provide a spray head for spray cans allowing to avoid a large driving agent consumption as a consequence of admixture, which spray head is intended, in the first place, for spray cans with air drive, but can also be applied with spray cans of the first-mentioned kind, and then the ejection of undesired driving gas can be reduced or avoided.
To that end the spray head of the invention is formed as characterised in claim 1.
In this manner ambient air is used as the additional mixing gas, so that the consumption of pressurised driving agent is reduced accordingly.
From NL-A 67 08 525 a spray head for a spray can is known, comprising a jet pump to be operated by propellant gas from the can, the pressure reduction being used for drawing a foamable liquid upwards from the can, additional passages communicating with the outside being present for drawing ambient air inwards, the propellant and the air being used for forming a foam. This jet pump does not comprise a jet nozzle for forming droplets to be ejected as a mist.
This spray head can be constructed in various manners, as defined in the subclaims.
The invention will be elucidated below by reference to a drawing, showing in:

Fig. 1 a diagrammatical representation of a spray head for elucidating the principle of the invention; and
Figs. 2 and 3 cross-sections of practical embodiments of the spray head of the invention.

The principle of the invention is diagrammatically represented in Fig. 1. Therein a spray head 1 is shown in a simplified manner, which head comprises a stem 2 with a bore 3, which stem is to be mounted on a spray can, and is designed for opening a dispensing valve not shown when being pressed downwards. Then the liquid to be sprayed will be driven into the bore 3 by the gas or vapour pressure acting within the spray can.
At its upper end the bore 3 is continued by a transverse bore 4 of a spray nozzle terminating in a dispensing aperture 6. So far the present head 1 corresponds with the current spray heads.
In the stem 2 a jet pump 7 is diagrammatically indicated. This pump comprises a jet nozzle 8 through which the liquid driven through the bore 3 flows, said nozzle 8 opening into a wider chamber 9 communicating, via an additional bore 10, with the ambient air.
When the liquid flows through the bore 3,because of the negative pressure generated thereby in the chamber 9, air will be sucked inwards in the known manner through the bore 10, and will be mixed with the liquid, which will be enhanced by arranging means for forming turbulences in the chamber 9. As a consequence thereof the mist jet emerging from the aperture 6 is mixed with air to such an extent that the liquid droplets formed will not coalesce, and a fine mist is obtained.
As, now, ambient air is used for supporting the spraying, no gas from the pressure space of the spray can is to be used anymore. In the case of an evaporating and often noxious driving agent this means less air pollution, and, when using an air pump for providing the interior pressure in the spray can, an air charge can be used longer so that less pumping is required.
The jet pump 7 diagrammatically shown can be realised in many other ways, e.g. in the form of a venturi tube. Moreover the location thereof in the bore 3 can be varied. It can be favourable to arrange it as closely as possible near the aperture 6, and this in view of manufacturing as well in view of the mixing effect.
In Fig. 2 a first practical embodiment of the spray head 1 is shown. The parts thereof corresponding with Fig. 1 have been indicated therein with the same reference numerals.
The transverse bore 4 terminates into a substantially annular chamber 11 into which a cylindrical cap 12 has been inserted which has a front wall 13 in which the aperture 6 is provided. The wall 13 defines, together with an end face 14 of a central piece 15 of the nozzle portion 5, a chamber 16 communicating with the bore 4 in which sloping baffles 17 can be arranged in order to allow the liquid to be brought in a revolving motion before emerging through the aperture 6.
A thin tube 18, having a bore which forms the air suction passage 10, ends beyond the end face 14 coaxially in the aperture 6 which is so much wider than the end of the tube 18 that the liquid flowing through the bore 4 and chamber 16 can emerge along the tube end outwards. This tube end and the aperture 6 form together the jet pump 7 as well as the spray nozzle 8 of Fig. 1.
This embodiment of the nozzle 5 is of the current design with the exception of the additional tube 18 opening into the aperture 6 which adaptation can easily be realised.
Fig. 3 shows still another practical embodiment in which, again, parts corresponding with Figs. 1 and 2 have been provided with the same reference numerals.
Here the tube 18 has been omitted, and before the end face 13 of the cap 12 a disc 19 directed parallel thereto is provided which, together with this end face 13, defines a passage 10′ forming the air suction passage. Near the outer edge of the disc 19 air suction openings 20 are provided, and in the centre of this disc an aperture 6′ has been formed which is situated coaxially with the aperture 6 of the cap and has substantially the same diameter. Also the passage 10′ can be provided, if required, with guiding baffles for imparting a revolving motion to the air flow sucked in, which motion, as the case may be, can be opposite to that of the revolving motion of the liquid caused by the baffles 17.

Claims

A spray head for a spray can, comprising a hollow stem having a bore which is adapted to be brought into communication with the liquid space of the spray can, and which on the other hand, terminates in a spray nozzle having an exit aperture, so as to force liquid driven into said bore by the internal pressure of the spray can through said aperture for being sprayed, characterised in that said spray nozzle (8, 16) opens into a passage operating as a jet pump (7) driven by the liquid flow pressed outwards, an additional passage (10, 10′) being provided which connects the suction side of said jet pump (7) with the ambient air.
The spray head of claim 1, characterised in that the passage operating as a jet pump (7) is formed by an additional passage (18) in the head (5), which opens separately from the liquid passage (4, 16) into the exit aperture (6), said aperture being so much wider than the outer periphery of said additional passage (18) that a passage for the liquid emerging from the liquid passage (16) remains free.
The spray head of claim 2, in which the bore of the stem opens into an annular chamber communicating with the exit aperture, characterised in that the additional passage (18) is a bore (10) extending substantially coaxially with the annular chamber (16), a wall (14) defining this chamber being provided with a projection extending into said aperture and surrounding the end of said bore (10).
The spray head of claim 1, in which the exit aperture has been formed in a disc closing the liquid passage, characterised in that the passage operating as a jet pump (7) is formed by a second disc (19) arranged at the exit side of the former disc (13) and at a small distance thereof and parallel thereto, said second disc (19) being provided with a second aperture (6′) situated coaxially in respect of the first aperture and having substantially the same diameter, the interspace (10′) between both discs (13, 19) communicating (20), near the circumference, with the surroundings.
The spray head of claim 4, characterised in that in the interspace (10′) between both discs (13, 19) guiding baffles are provided which are adapted to impart a revolving motion to the air flow sucked therethrough.