NOZZLE UNIT

Abstract: A nozzle unit for use at a precise dosage of liquid in small quantities and which comprises a nozzle body (1) with a substantially conical nozzle duct (5) in a region near by the nozzle orifice (6) may meet the conflicting requirements concerning a large section of the nozzle orifice for a high rate of throughput, and a small section of the nozzle orifice for a small drop size so as to obtain a high accuracy of dosage. This is the case if the nozzle body (1), at least in the region (4) in the immediate vicinity of the nozzle orifice (6) is made of elastical material, preferably acid-proof rubber. In case such a nozzle unit is intended to work with high pressures it may be provided with a reinforcement, e.g. in the form of a surrounding tube (7), so as to prevent the occurence of the so-called balloon-effect.

Description: NOZZLE UNIT Background of the Invention The present invention relates to a nozzle unit for use at a pre¬ cise dosage of liquid in small quantities comprising a nozzle body, which has a substantially conical nozzle duct in the region near by the nozzle orifice and which at least in the region in the immediate vicinity of the nozzle orifice is made of elastic material, preferably acid-proof rubber. From the specifications of US patents No. 3,129,894 and No. 3,612,409 nozzle units are known which have a substantially conical nozzle duct and which are made of resilient material. However, none of the nozzles disclosed are suited for use at a precise dosage of liquid in small quantities, seeing that the two nozzles disclosed, have an increasing material thichness in the region near by the nozzle orifice so as to obtain a substantially firm nozzle duct for producing of high rates of flow. It is known that the accuracy of discharge of a nozzle depends on the dimensions of the orifice of the nozzle. In obtaining a high accu¬ racy it is necessary to use a small nozzle orifice, in that a small orifice provides for a high accuracy, whereas a bigger orifice, owing to the size of the drop at the nozzle orifice, permits a less accuracy of dosage only. However, it is advisable to reduce the time used for the dosage and in case an excessive drop of pressure across the nozzle should be avoided this will require a bigger orifice. In case big nozz- le orifices are used it is necessary to provide a source of vacuum, which is connected with the nozzle at the end of the discharge so as to ensure that a big drop at the orifice will not "fall off" and here¬ by reduce the accuracy of dosage. It is obvious that the manufacture of such a structure is complex and expensive. Accordingly, conflicting requirements exist concerning the struc¬ ture of the nozzle, and it is the purpose of the present invention to comply with these requirements in providing an especially simple and inexpensive nozzle unit allowing both a comparative high rate of throughput and a high accuracy of dosage. According to the present invention this is achieved by means of a nozzle unit of the type referred to in the introductory paragraph cha¬ racterized in that a part of the nozzle body length arranged remotest from the nozzle orifice is provided with a reinforcement, which extends to a region in the immediate vicinity of the nozzle orifice, so that only the elastic material in the immediate vicinity of the nozzle ori¬ fice is able to expand as a result of high pressure in the nozzle, whereby a variable nozzle orifice is imparted to the nozzle. A nozzle unit is hereby obtained which in a structural simple way is imparted a variable nozzle orifice, which may be adapted to fluids of different viscosities and different rates of flow by a convenient choise of elastic material and wall thichness, which choice will be possible to a skilled in the art. By its design and dimensions the reinforcement ensures that a so-called balloon effect will not occur, which otherwise, might cause an inaccurate dosage or a rupture of the elastic material. With a nozzle orifice provided in such a way, it becomes possible to work with a bigger drop of pressure across the nozzle, and accordingly, a higher rate of throughput as a higher pres¬ sure in the nozzle will cause an expanding of the nozzle orifice, whe¬ reby the throughput may be increased, and simultaneously, when the pressure inside the nozzle falls and due to the elasticity of the ma¬ terial a contraction will occur, and hereby the nozzle orifice will reassume its small section ensuring a high accuracy of dosage, in that a big drop will not occur at the nozzle orifice at the end of the dis¬ charge, which otherwise could fall off and reduce the accuracy of dosa¬ ge. In a preferred embodiment of the invention the nozzle unit is characterized in that the nozzle body throughout is made of elastic material and that the reinforcement comprises an increase of the mate¬ rial thickness in the wall of the nozzle body. Hereby a nozzle body with the above mentioned structure is obtained which is provided with an especially simple reinforcement excluding the balloon effect and, wherein the nozzle body and the reinforcement can be made by casting of a single material. This type of nozzle unit will especially be ap¬ plicable in connection with nozzle units where moderate pressures occur in that it is possible to prevent the occurrence of the balloon effect solely by means of the material increase. According to a further preferred embodiment of the invention the nozzle unit is characterized in that the reinforcement comprises a substantialle non-elastic tube with a length shorter than the length of the nozzle body and that the tube is arranged surrounding the nozzle body or embedded therein. Hereby a nozzle unit is obtained wherein occuring of the balloon effect in the nozzle body is prevented in a safe way. Particularly this is the case when a tube surrounding the nozzle body has a length such that it partly extends out over the conical part of the nozzle body, seeing that the balloon effect is most likely to occur in the vicinity of the transition between the conical part and the cylindrical part, where an increase of pressure arises due to the reduced section. In a convenient embodiment the surrounding tube has a length of about 80 - 95% of the length of the nozzle body as it hereby becomes possible to prevent the balloon effect to occur at any position along substantially the whole extension of the conical part rather than at the transition between the conical part and the cylindrical part. In an advantageous embodiment of the nozzle unit for discharging of tint to a base paint the nozzle body has a length of 50 mm and an inner diameter of about 5 mm at the collar, and the surrounding tube has a length of about 40 - 45 mm. Hereby a reinforcement of substantially the whole extension of the nozzle unit is obtained when a high pressu¬ re, by discharges of tint, is created inside the duct, which pressure expands the conical nozzle duct to abut on the surrounding tube. The surrounding tube may not have a length corresponding to or greater than the length of the nozzle body, since hereby a risk arises for adhering drops which might fall off and reduce the accuracy of dosage. Description of the Drawings The invention will hereinafter be further explained with referen¬ ce to the drawing wherein, Fig. 1 shows a section through a nozzle unit according to the present invention Fig. 2 shows a section through the nozzle unit of Fig. 1 and a surrounding tube, and Fig. 3-6 sections, in a reduced scale through further embodiments of a nozzle unit according to the present invention. On Fig. 1 a nozzle unit 1 is shown, comprising a collar 2 for securing and fixing of nozzle body as regards a holder (not shown). The nozzle body 1 comprises a cylindrical part 3 and a substantially conical part 4 with a conical nozzle duct 5. The conical nozzle duct 5 extends from the nozzle orifice 6 over the greater part of the whole length of the nozzle body 1. The nozzle body 1 has substantially con¬ stant wall thickness over the whole length and is made of acid-proof rubber, to resist aggressive constituents, such as solvents in the discharged fluid. The elasticity of the rubber will depend on the in¬ tended use, and it can be chosen with due regard to the properties requested for the nozzle. On Fig. 2 a corresponding nozzle body 1 is shown, which is provi- ded with a reinforcement in the form of a tube 7. Hereby it will be possible to use the nozzle body 1 shown in connection with a greater pressure drop across the nozzle. The tube 7 extends from the collar 2 beyond the transition 8 between the cylindrical part 3 and the conical part 4. Accordingly, at the transition 8 where the section is decreased and where the largest stresses on the wall of the nozzle body occur, the tube 7 will insure that no balloon effect arises in the nozzle body 1 since the expansion thereof is limited of the non-elastic tube 7. When fluid is dosed through the nozzle an increase of the pressu- re, during a period of maximum throughput, will cause an increase of the nozzle orifice 6, as the elasticity of the material is overcomed by the pressure in the duct 5. Hereby it is possible to obtain a high rate of throughput. When the input to the nozzle is cut off, the pres¬ sure will drop at the end of the dosage and, accordingly, the elasti- city of the material of the wall of the nozzle body again will overco¬ me the pressure in the duct 5, and the nozzle body reassumes its origi¬ nal unstressed configuration. Hereby a nozzle orifice 6 with a small magnitude is obtained, and accordingly, a high accuracy depending on the size of the drop at the nozzle orifice 6 is obtained. Figs. 3-6 show further embodiments of the nozzle body intended to be made of the same material as is the nozzle body shown on Figs. 1 and 2. Fig. 3 shows a nozzle body 1, wherein the cylindrical part 3 is of a length considerably larger than the length of the substantially conical part. This nozzle body may be sourrounded by a tube (not shown) corresponding to the tube 7 of Fig. 2. Fig. 4 shows a nozzle body 1, wherein the substantialle conical part is extending wholly along the length of the nozzle body 1. This nozzle body, too, may be surrounded by a tube corresponding to the tube 7 of Fig. 2. Figs. 5 and 6 show two nozzle bodies, each of which integrally is provided with a reinforcement. On Fig. 5 the nozzle body 1 is provided with a reinforcement in the form of a tube 10 embedded in the very wall 9 of the nozzle 1, in the cylindrical part 3 thereof. The tube illustrated extends wholly along the length of the conical part 3. On Fig. 6 the nozzle body is provided with a reinforcement in the form of an increase of the wall thickness, extending along a part of the length of the nozzle body. This increased wall thickness will in the embodi¬ ment shown substantially extends along the whole length of the cylin¬ drical part. Though nozzle bodies with cylindrical and conical configuration have been explained and illustrated in the above, it is obvious that the nozzle body may be made with a curvature, starting at the nozzle orifice 6 and extending wholly or partly along the length of the nozz¬ le body 1. An example of the accuracy obtainable with a nozzle unit according to the present invention may be given. In connection with an embodiment substantially corresponding to the embodiment illustrated on Fig. 1, an accuracy of dosage of 0,05 ml, depending on the drop size at the nozzle orifice, has been achieved. This has been achieved in a nozzle unit, which has a rate of throughput of 10 ml/sec at a pressure of 2,8 bar as measured in the nozzle body orifice. The nozzle unit employed had a length of about 50 mm, an inner diameter of about 5 mm at the collar 2 and a diameter of about 0,5 mm at the nozzle orifice 6 and the fluid employed had a viscosity substantially corresponding to the viscosity of water.

Claims: C l a i m s 1. Nozzle unit for use at a precise dosage of liquid in small quantities comprising a nozzle body, which has a substantially conical nozzle duct (5) in the region near by the nozzle orifice (6) and which at least in the region (4) in the immediate vicinity of the nozzle orifice (6) is made of elastic material, preferably acid-proof rubber, c h a r a c t e r i z e d in that a part (3) of the nozzle body length arranged remotest from the nozzle orifice is provided with a reinforce¬ ment (3,7,10), which extends to a region in the immediate vicinity of the nozzle orifice, so that only the elastic material in the immediate vicinity of the nozzle orifice is able to expand as a result of high pressure in the nozzle, whereby, a variable nozzle orifice is imparted to the nozzle. 2. Nozzle unit according to claim 1, c h a r a c t e r i z e d in that the nozzle body throughout is made of elastic material and that the reinforcement comprises an increase (3, Fig. 6) of the material thickness in the wall (9) of the nozzle body. 3. Nozzle unit according to claim 1, c h a r a c t e r i z e d in that the reinforcement comprises a substantially non-elastic tube (10) with a length shorter than the length of the nozzle body, and that the tube (10) is arranged embedded in the nozzle body. 4. Nozzle unit according to claim 1, c h a r a c t e r i z e d in that the reinforcement comprises a substantially non-elastic tube (7) with a length shorter than the length of the nozzle body, and that the tube (7) is arranged surrounding the nozzle body. 5. Nozzle unit according to claim 4, c h a r a c t e r ! * z e d in that the surrounding tube has a length such that it partly extends out over the conical part (4) of the nozzle body (1). 6. Nozzle unit according to claim 4 or 5, c h a r a c t e r i z e d in that the tube (7) has a length of about 80 - 95% of the length of the nozzle body. 7. Nozzle unit according to claim 4,5 or 6, c h a r a c t e r i ¬ z e d in that the nozzle body has a length of 50 mm and an inner dia¬ meter of about 5 mm at the collar (2), and that the surrounding tube (7) has a length of about 40 - 45 mm.

Inventors: HANSEN OLE KOUSTRUP, WASS RENE JOHNNY BERNHARD, HANSEN, OLE, KOUSTRUP, WASS, RENE, JOHNNY, BERNHARD
Applicants: ON COMPUTER ELECTRONICS A S, ON COMPUTER ELECTRONICS A/S
Application year: 1987
Main classification: B05B1
IPC codes: B05B1, F16L59