EP0879644B1

EP0879644B1 - Delivery lance with rotary nozzle

Info

Publication number: EP0879644B1
Application number: EP97202633A
Authority: EP
Inventors: Giuseppe Arsi; Erminio Landini
Original assignee: Interpump Group SpA
Current assignee: Interpump Group SpA
Priority date: 1997-05-22
Filing date: 1997-08-28
Publication date: 2004-07-07
Anticipated expiration: 2017-08-28
Also published as: EP0879644A2; DE29716005U1; EP0879644A3; ITRE970034A1; IT1294433B1; DE69729788T2; DE69729788D1; ATE270587T1

Abstract

A high-pressure water delivery lance with rotary nozzle (11) comprises a cylindrical chamber (10) known as the stator, which is fed with pressurized water via at least one tangential conduit the direction of which has an axial component, and in which there rotates a nozzle (11) known as the rotor having an at least partly frusto-conical wall which rolls on the chamber surface, a sized axial hole and an end sealedly resting in an end seat of the chamber, the rotor and stator being formed of materials having between them a dynamical friction coefficient of less than 0.20. <IMAGE>

Description

This patent relates to pressurized water delivery lances of the rotary nozzle type, as usually used in hot or cold water jet washers. Such a water delivery lance according to the preamble of claim 1 is s known from US 4 542 853.
Rotary nozzle delivery lances comprise a cylindrical chamber into which the water to be delivered is fed at high velocity in a direction at least partly tangential, ie having a tangential component, and which has an axial exit hole acting as the support seat for a nozzle.
The nozzle is in the form of a body with an at least partly conical wall arranged to rest against the inner surface of the cylindrical chamber, and at its top a spherical surface arranged to bear under hydraulic seal conditions against the axial exit hole of the chamber, said body also having a narrow axial hole from which the pressurized water emerges.
The nozzle is immersed in a body of liquid in the form of the water filling the chamber, in which body of liquid the nozzle lies in an inclined position with its top resting against the axial exit hole of the chamber, and its lateral wall resting against the chamber.
By virtue of the rotation of the body of liquid impressed on the water by its axial feed, the nozzle is subjected to rotary motion about the chamber axis, by which the water jet leaving the nozzle travels in the form of a conical surface having a vertex angle double the inclination of the nozzle axis to the chamber axis.
In known devices said rotary motion has a velocity of the order of 2000-3000 r.p.m.
Rotary nozzle delivery devices of the aforedescribed type operate more effectively the higher the rotational velocity of the nozzle about the axis of the cylindrical chamber containing it.
However the mode of operation of said devices also induces rotation of the nozzle about its own axis, in the opposite direction to the rotation of the nozzle about the chamber axis.
If the rotational velocity of the nozzle about its axis exceeds certain limits, it causes an undesirable phenomenon in the form of disintegration of the jet leaving the nozzle due to centrifugal force.
The rotational velocity of the nozzle about its axis is regulated by regulating the friction coefficient, or rather the friction force, arising from the sliding of the nozzle against the cylindrical wall of the chamber.
It is considered that the friction coefficient between the cylindrical chamber surface and the nozzle body must conveniently exceed 0.25.
Effectively, because of the friction the nozzle is rotated in the opposite direction to the direction of rotation of the body of liquid containing the nozzle at a velocity proportional to the friction coefficient.
Indicatively it can be considered that with a friction coefficient of 0.25 and an average nozzle diameter of one half the chamber diameter, the velocity of rotation of the nozzle about its axis is about one half the velocity of rotation of the nozzle about the chamber axis and is in the same direction thereas.
A serious drawback of the aforesaid known art is that the need to maintain a high rotational velocity of the body of liquid containing the nozzle, the braking action exerted between the chamber surface and the nozzle surface, and the consequent turbulence of the body of liquid give rise to negative phenomena.
These are mainly represented by a pressure drop which can be considerable, and hence a reduction in the general efficiency of the delivery lance.
In the case of low power devices, such as non-professional devices, said pressure drop can significantly compromise the device efficiency.
The object of the present invention is to optimize the velocity of rotation of the nozzle about its own axis and about the axis of the cylindrical chamber which contains it, while at the same time minimizing the pressure drop and consequently the turbulence in the body of liquid containing the nozzle.
This object is attained by choosing the materials of the nozzle (the rotor) and of its containing chamber (the stator) such as to minimize the friction coefficient between them.
It has been surprisingly noted that by reducing the relative velocity between the rotor and stator to a value close to zero, turbulence in the body of water containing the rotor is substantially reduced, with consequent substantial reduction in energy dissipation, turbulence and the drawbacks deriving therefrom.
For equal rotational velocities of the body of water containing the nozzle, the water feed conduits to the stator can be not only of greater cross-section but also possibly have an axial direction with a lesser tangential component.
The resultant pressure drop enables water to be fed to the stator at a lower pressure without compromising the effectiveness of the exit jet, so allowing jet washers to be constructed of lower power and cost than currently known jet washers of equal performance.
This result is very important not so much for professional jet washers, as for those for the hobbyist for which there is an ever increasing demand and for which absorbed power and small dimensions determine their commercial success.
The merits and constructional and operational characteristics of the invention will be more apparent from the detailed description given hereinafter with reference to the figures of the accompanying drawings, which show a preferred embodiment thereof.
Figure 1 is a section through a delivery lance or gun according to the invention.
Figure 2 is an enlarged detail thereof comprising the rotary nozzle.
The figures show a delivery Lance comprising a tubular-body 1 acting as a handgrip 2, connected at one end 3 to the water feed hose and having a delivery end 4.
The end 3 communicates with a piece 6 containing the rotary nozzle, as best seen in Figure 2.
The piece 6 is substantially shaped as a cup 7 having in its end an axial aperture 8, and having an internal section which tapers stepwise towards its end.
The widest part of the cup 7 sealedly receives the end of the water feed conduit, having a closed head 91 in which peripheral inclined ducts 92 are provided.
Said peripheral ducts open into the cup 7, in proximity to its wall, in a direction having a tangential component.
The head 91 of the conduit 9 defines within the cup 7 a chamber 10 containing a nozzle 11.
At that of its ends distant from the head 91, the nozzle comprises an insert 110 of ceramic or another suitable hard anti-wear material, which is of hemispherical shape and sealedly rests in a conjugate ceramic seat provided in a ring 71 inserted into the narrowest section of the cup 7.
The body of the nozzle 11 has a frusto-conical portion 111 intended to rest against the inner cylindrical wall 72 of the cup 7, and an axial sized duct 112 having a diameter which in the illustrated example is 1.25 mm.
In the illustrated example two ducts 92 are provided, each of 1.5 mm² cross-section, their inclination to the plane perpendicular to the axis of the chamber 10 being 0°.
They induce in the body of water contained in the chamber 10 a velocity of rotation about the chamber axis not exceeding 4000 r.p.m.
The velocity of rotation of the nozzle 11 about its own axis is at least 10% less than its velocity of rotation about the axis of the chamber 10.
The cup 7 is constructed of acetal resin monopolymer filled with teflon micropowder, which has a dynamic friction coefficient against itself of the order of 0.30.
This resin (deldrin + teflon) is known as DE9156 and is manufactured and marketed by Du Pont de Nemours Italiana S.p.A.
The body of the nozzle 11 is constructed of acetal resin monopolymer modified with silicone, which has a dynamic friction coefficient against itself of the order of 0.10, is known as DE8903 and is manufactured and marketed by Du Pont de Nemours Italiana S.p.A.
The dynamic friction coefficient between said two materials is about 0.19 under dry conditions, and much less under wet conditions.

Claims

A high-pressure water delivery lance with rotary nozzle, comprising a cylindrical chamber known as the stator, which is fed with pressurized water via at least one tangential conduit the direction of which has an axial component, and in which there rotates a nozzle as the rotor, characterized by an at least partly frusto-conical wall which rolls on the chamber surface and rests on this latter along the whole length of its generatrix, a sized axial hole and an end sealedly resting in an end seat of the chamber, and characterised in that the rotor and stator are formed of materials having between them a dynamical friction coefficient of less than 0.20.
A high-pressure watar delivery lance with rotary nozzle (11) as claimed in claim 1, characterised in that the constituent materials of the rotor and stator are synthetic resins.
A high-pressure water delivery lance with rotary nozzle (11) as claimed in claim 1 , characterised in that the constituent materials of the rotor and stator are acetal resins.
A high-pressure water delivery lance with rotary nozzle (11) as claimed in claim 1, characterised in that the constituent materials of the rotor and stator are acetal resins filled with teflon micropowder.
A high-pressure water delivery lance with rotary nozzle (11) as claimed in claim 1, characterised in that the constituent materials of the rotor and stator are acetal resins modified with silicone.