Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B1/00—Nozzles, spray heads or other outlets, with or without auxiliary devices such as valves, heating means
  • B05B1/005—Nozzles or other outlets specially adapted for discharging one or more gases

Definitions

• the present invention relates to a further development of the blowing tool described in the mentioned patent.
• Fig. 1 is a longitudinal section view.
• the gas is supplied to the tool through a high pressure hose 2 which is connected to the gas source and has a high pressure above atmospheric.
• a hand grip 3 is depressed, a valve slide 4 being moved so that gas can pass through a groove in the slide and an extension tube 6 out through the mouth 7 of the extension tube.
• the pressure before the mouth at which critical pressure ratio can be obtained is determined by the counter pressure after the mouth which in its turn is influenced by the degree of coejection, i.e. to which extent the air jet leaving the mouth in its motion takes the ambient air with it, in such a way that the higher co-ejection which can be obtained the higher supply pressure can be applied on the high pressure hose 2 before the critical pressure ratio is reached.
• the resulting higher density of the gas gives larger blowing force in addition to the supplementary blowing power that co-ejected air gives. If the interior of the blowing tool is designed so as to achieve low losses, i.e.
• the pressure of the gaseous medium immediately before the outlet would substantially correspond to the applied supply pressure within the high pressure hose 2, i.e. at normally occurring supply pressure of 6-8 bars the pressure of the gas immediately before the outlet would be substantially equal to 6-8 bars.
• the pressure of the gas would, if all the air passages before the outlet are substantially greater than the outlet passage, after expansion be greater than 3.15 bars, i.e. more than 3 times the pressure existing around the tool.
• the object of the. present invention which is based on studies is to provide a blowing tool having a low noise level, a great blowing power and a high mecanical efficiency.
• a blowing tool according to the invention has the characteristic features stated in the claims.
• Figs. 2 to 9 show examples of blowing tools according to the invention.
• the gas is supplied to the tool through a connection 8 and passes through a passage between the valve plate 9 and the valve seat 10 as the front rubber cone 11 is tilted.
• this passage is greater than 0.5, suitably greater than 0.65, preferably greater than 0.8 times the total outlet area of the outlet apertures 12 at the nozzle 13, i.e. preferably so that the velocity of the gas at the valve passage is lower than the velocity of the gas at the outlet passage, so that the generation of noise at the valve preferably is lower than the generation of noise at the outlet.
• valve passage By having the outlet apertures spaced from each other a large distance the valve passage can advantageously also be made larger, preferably substantially larger than the total outlet passage, so that in the main the whole supply pressure connec ted to the blowing tool can be utilized, i.e. the gas pressure in the chamber 14 can advantageously be essentially equal to the supply pressure.
• the front part of the tool can be formed as a cylinder, a trun cated cone or with the chamfering increasing towards the nose.
• the outlet passages can advantageously end. near or in the mantle surface as appears from Figs. 2-5 and Figs. 6-7 respectively.
• the outlet apertures are so positioned that co-ejection is obtained around the whole periphery of each partial jet.
• this can in practice be realized a.o. by placing the outlet apertures 12 on a circle the diameter D of which is greater than 4 times the diameter d of the largest outlet passage, which is less than 2 mm, preferably at the most 1.5, e.g. about 1 mm, and by spacing the apertures with a large distance and substantially not within the central parts of the nozzle.
• the outlet apertures should be positioned with a mutual centr distance which is larger than 2 times the diameter of the aperture for outlet apertures which are less than 1 mm.
• the mutual centre distance should be greater than 2 times the square of the dia meter of the aperture . In this way also a reduced mutual inte action between the outgoing gas jet is obtained.
• more than 10 %, suitably more than 20 % , preferably more than 40 %, of the outlet area should be positioned outside a surface A c , which is 3 times greater than the sum A ut of the cross sectional areas of the outlet passages, A c being situated so that its centre of gravity coincides with the centre of gravity of a form area A f situated in the same plane as A c , being uniform with A c and with the smallest possible periphery containing the outlet areas of all the exhaust passages.
• the largest cross sectional dimension of the outlet jet should be at the most 2 mm, preferably at the most 1-5 mm, e.g. about 1 mm, i.e. for circular outlet apertures the diameter should be at the most 2 mm, preferably at the most 1.5 mm and can e.g. be about 1 mm. for a.o. having a fast pressure equalization between the ambient pressure and the pressure in the central parts of the gas jet.
• a form area A f is first designed by connecting the outer outlet apertures in the picture of the apertures with straight lines which in relation to the centre of the picture of the apertures are tangents to the outer side at the outer apertures.
• the area A c is so situated that its centre of gravity coincides with the centre of gravity of the form area A c
• Each side of A c is parallel to the corresponding side of the form area A f .
• the area A is thus projected symmetrically around the centre of the circle.
• the mantle 15 at the termination of the nozzle can be conical or tapering as in one of the shown embodiments.
• Half of the cone angle, ⁇ according to Fig. 4 should then be less than 20°, however not less than 10°.
• the outlet aper tures should be spaced with a centre distance exceeding 1.5 preferably exceeding 2 times the diameter of the aperture for the outlet passages which is less than 2 mm, preferably less than 1.5 mm, e.g. 1 mm.
• more than 10 %, preferably more than 20 %,and best more than 40 %, of the sum Aut. of the cross sectional area of the exhaust passages at the outlet, transversally to the direction of the flow, should be placed outside an.area A which is 2 times larger than A ut , A being so located that its centre of gravity coincides with the centre of gravity of a form area A f , situated in the same plane as A c , being uniform with A c and completely enclosing with the smallest possible periphery the outlet areas of all the outlet passages.
• Half of the cone angled for the nozzle should then be between 10° and 20°, and in addition it is assumed that the direction of the flow from the outle passages does not deviate more than 10° from the axis of the cone.
• the termination of the nozzle can advantageously be provided with means 16 projecting from the nozzle body as shown in Figs.2 and 4 to 9, which are so designed that they do not influence the co-ejection capacity of the nozzle or otherwise disturb the outflow of gas. It is important that the nozzle has this mechanical shield, because if for instance only one of the outlet apertures should be deformed, for instance by a burr or a flash arising within the flow area, this will result in an increase of. the noise leve which can be of 3to4 dB (A).
• the increase in the noise level should be placed on an equality, as regards the risk of impaired hearing, with an increase of the noise level of 13-14 dB (A) for a wide band noise.
• the exhaust passages of the nozzle together give directed exhaust of the gazeous fluid from the nozzle.
• the hypothetical central lines of the passages in the direction of the fluid flow can be parallel to each other, but this is not necessary, as said central linescan diverge up to about 20 or even 30° between themselves and in relation to the exhaust direction of the nozzle and yet give a directed jet of fluid from the nozzle.
• Annularly arranged exhaust passages of a nozzle having a conically mantle can for instance have their central lines located on a hypothetical conical surface situated inside and presenting a smaller cone angle than the conical mantle of the nozzle.
• Prototypes of the device according to the invention in accordance with the embodiments illustrated in Figs. 2 to 9 have been subjected to practical testing and have been compared with most commercially available so-called silent blowing nozzles having a body of porous, sintered metal inserted into the exhaust tube. and have also been compared with the majority of conventional blowing nozzles. In all the cases for a given blowing power in addition to a higher air consumption the noise level was considerably higher for the comparison nozzles than for the blowing tool according to the invention.

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• Jet Pumps And Other Pumps (AREA)
• Nozzles (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

Family

ID=20339540

Family Applications (1)

Country Status (9)

Cited By (1)

Families Citing this family (4)

Family Cites Families (6)

• 1979
  • 1979-12-12 SE SE7910235A patent/SE7910235L/ unknown
• 1980
  • 1980-12-09 JP JP56500179A patent/JPH0316182B2/ja not_active Expired - Lifetime
  • 1980-12-09 DE DE8181900027T patent/DE3068922D1/de not_active Expired
  • 1980-12-09 WO PCT/SE1980/000327 patent/WO1981001668A1/en active IP Right Grant
  • 1980-12-09 EP EP81900027A patent/EP0041534B1/de not_active Expired
  • 1980-12-11 IT IT26560/80A patent/IT1134668B/it active
  • 1980-12-11 BE BE0/203121A patent/BE886598A/fr not_active IP Right Cessation
• 1981
  • 1981-07-20 DK DK323781A patent/DK323781A/da not_active Application Discontinuation
  • 1981-07-23 FI FI812316A patent/FI69256C/fi not_active IP Right Cessation

Non-Patent Citations (1)

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