WO1992005878A1

WO1992005878A1 - Jet assembly for powder sprayers

Info

Publication number: WO1992005878A1
Application number: PCT/SE1991/000680
Authority: WO
Inventors: Ingemar LÖÖF
Original assignee: Icoma Ab
Priority date: 1990-10-09
Filing date: 1991-10-09
Publication date: 1992-04-16
Also published as: SE9003216D0; SE9003216L; SE467527B

Abstract

A jet assembly for powder sprayer has a plurality of outlet orifices (12), in which outlet jets are intended to be mounted. At least one annular tube (4, 6) is connected to the sprayer mouth. Means are disposed in the tube for causing the powder to rotate during its passage through the tube, and the outlet orifices are formed in the wall of the tube.

Description

Jet Assembly for Powder Sprayers

The present invention relates to a jet assembly for powder sprayers with a plurality of outlet orifices in which outlet jets are intended to be mounted.

It is previously known to connect to the outlet of a powder sprayer four, substantially axially directed outlet jets. It is also previously known to arrange in the outlet tube of a powder sprayer a plurality of thin plastic tubes through which the powder is ejected. The tubes are twisted together helically, and have their ends extending beyond the outlet tube, so that the spray pattern obtained may be changed by bending the end portions of the tubes. A draw-back of this implementation is that the arrangement of a plurality of helically twisted tubes inside the outlet tube is compli- cated.

The object of the present invention is to enable variation of the spray pattern into desired configurations in a con¬ siderably simpler manner than hitherto particularly for achieving a larger continuous spray width than has been possible so far.

This object is achieved by a jet assembly of the kind mentioned in the introduction and with the distinguishing features disclosed in claim 1.

With the assembly in accordance with the invention the additional advantage is obtained that the ejection rate is increased and that a better electrostatic charging is obtained of the powder in the case of friction charging.

In accordance with an advantageous embodiment of the assembly according to the invention, the directions of the outlet ori¬ fices are individually adjustable, thus enabling the spray pattern to be easily adapted to the application in question.

The jet assembly tube is preferably made up from a plurality of sections, each being provided with an outlet orifice and being turnable relative to the others for directing the ori¬ fices in a desired manner. In many applications it is de¬ sirable to arrange the orifices in a straight line along the length of the wall of the tube, thus providing a continuous powder curtain over the desired spray width.

In accordance with another advantageous embodiment of the assembly according to the invention, means are provided, in the form of an elongated core, centrally disposed in the tube and at least one turbulator for causing the powder to rotate. This is important, partly for providing effective friction charging of the powder in this configuration of the sprayer and partly for enabling effective ejection of the powder through the orifices in the tube wall.

In accordance with another advantageous embodiment of the assembly according to the invention, the central core may be removed from the tube through the end thereof opposite to the connection member, whereby cleaning of the inside of the tube, the turbulator and the central core is easily accomplished.

The entire jet assembly can be formed as a unitary con¬ struction, so that the whole assembly may be removed, e.g. for changing the spray pattern. Alternatively, the tubes may be removably mounted in the connection member.

The assembly according to the invention is particularly suitable for use with a powder sprayer of the ionizing type, the assembly according to the invention being made from a material, e.g. teflon, suitable for friction charg¬ ing of the spray powder. However, the assembly according to the invention may also be used in a sprayer where powder pre- charged by electrodes is used. An embodiment of the assembly according to the invention, selected as an example, will now be described in more de¬ tail with reference to the accompanying drawing, where:

Fig 1 illustrates the assembly according to the invention in lateral view in an assembled state,

Fig 2 is a longitudinal section of a jet assembly tube according to the invention, and

Fig 3 is a cross section of a connection member of the assembly according to the invention.

The assembly according to the invention includes a connec- tion member 2 intended for fitting to the mouth of a powder sprayer. Two jet assembly tubes 4,6 are mounted to the con¬ nection member 2 via openings 8, 10 in the side wall thereof. Openings 8, 10 are diametrically opposed to each other, and in the example now described the tubes 4, 6 are exactly the same.

The two tubes may also be arranged tangential to the sprayer outlet conduit and oppositely to each other, and the assembly according to the invention may of course be formed with one tube, or more than two tubes, and of course the individual tubes can be differently formed. The tubes may also be made up from sections that can be put together and that can be turned in relation to each other, so that given direction is afforded for the outlet orifices .12, which are made in the wall of the tube, and in which outlet jets are intended to be disposed.

In the example illustrated in the figures, the outlet ori¬ fices 12 are arranged in line, in order to provide a con- tinuous spray powder curtain over the desired spray width. The positioning, direction and size of the orifices 12 may of course vary according to requirements. Thus the sizes of the individual orifices 12 may of course vary according to requirements. Thus the sizes of the individual orifices may alsy be varied, thus when necessary varying the amount of powder ejected from the different orifices.

A central core 14 is disposed inside the tube 4, such as to form an annular duct 16 between the central core and the inner face of the tube 4.

At the inlet portion of the tube 4, which is intended to be inserted into the opening 8 in the side wall of the connec- tion member 2, a turbulator 18 is disposed for providing the inflowing powder with a rotational movement, so that it will move helically along the duct 16 before it is ejected through the orifices 12. This helical movement of the powder is necessary for it to be effectively ejected through the orifices 12 and the helical movement further contributes to improved charging by friction in sprayers of the friction charging type.

The central core 14 may be removed from the tube 4 through the end of the tube opposite to the connection member, i.e. to the left in Fig 2, thus enabling in a simple way cleaning of the central core 14, the tube and the turbulator 18.

The central core is provided with a pointed Portion 20, and when the central core 14 is disposed in the tube 4 this portion 20 is fitted into a corresponding bore in the tur¬ bulator 18, such as to ensure a safe centering of the core in the tube 4.

The turbulator may, for example, be of the kind described in Swedish Patent 8701775-2, and more than one turbulator may be arranged along the tube 4. It is also possible to form the central core and the turbulator in one piece.

In Fig 3 the connection member 2 is shown in cross section. The connection member 2 is attached in a suitable manner to the mouth of the powder sprayer, e.g. by a screwing or some form of quick-release locking means. At its upper part, the connection means 2 is formed with a central, conical protuberance 22, which has been found p r- tant in achieving effective deflection of the powder from the sprayer into the radially extending ducts. The powder coming from the sprayer into the connection member normally rotates, and the protuberance 22 has a function to distribute the powder into the ducts.

Claims

1. Jet assembly for powder sprayers with a plurality of out- let orifices in which outlet jets are intended to be mounted characterised in that at least one annular tube is connected to the sprayer mouth, in which tube means are disposed for causing the powder to rotate during its passage through the tube, and in that outlet orifices are formed in the wall of the tube.

2. Assembly as claimed in claim 1, characterised in that a connection member is connectable to the sprayer mouth, and in that the tube is joined to the connection member perpendi- cularly to the sprayer outlet conduit, said connection member being adapted to deflect powder coming from the sprayer into the tube.

3. Assembly as claimed in claim 2, characterised in that two tubes are joined to the connection member, said tubes being disposed perpendicularly to the sprayer outlet conduit and mutually opposed.

4. Assembly as claimed in any one of claims 1-3, character- ised inthat the directions of the outlet orifices are individually adjustable.

5. Assembly as claimed in any one of claims 1-4, character¬ ised in that the tube is made up from a plurality of sections that can be interconnected.

6. Assembly as claimed in claim 5, characterised in that each section is provided with an outlet orifice, and in that after mounting together the sections to form a tube the sections are turnable relative each other for directing the orifices in a desired manner.

7. Assembly as claimed in any one of claims 1-3, character¬ ised in that the orifices are disposed in a straight line along the length of the wall of the tube.

8. Assembly as claimed in any one of claims 1-7, character¬ ised in that said means for causing the powder to rotate include an elongated core centrally disposed in the tube and at least one turblator.

9. Assembly as claimed in either of claims 7 and 8, char¬ acterised in that the turbulator is disposed in the inlet portion of the tube.

10. Assembly as claimed in either of claims 8 and 9, char¬ acterised in that the central core may be removed from the tube through the end therof opposite to the connection member.

11. Assembly as claimed in any one of claims 8-10, character¬ ised in that the central core has a pointed portion facing towards the turbulator, such that when the core is disposed in the tube this portion is fitted into an aperture formed in the turbulator for centering the core in the tube.

12. Assembly as claimed in any one of claims 8-11, character¬ ised in that the central body and the turbulator(s) are form- ed as one unit.

13. Assembly as claimed in any one of claims 2-12, character¬ ised in that the connection member ar.d the tube are formed in one piece.

14. Assembly as claimed in any one of claims 2-13, character¬ ised in that a central, conical internal protuberance is pro¬ vided in the connection member at its end wall opposite to the sprayer mouth.

15. Assembly as claimed in any one of claims 1-14, character¬ ised in that said assembly is made from a material, preferab¬ ly teflon, suitable for electrostatically charging the spray powder by friction charging.