Spray nozzle with directly mounted plate

Details Spray nozzle with directly mounted plate Spray nozzle with directly mounted plate

2000-06-21

2001-06-05

Scherbel, David A. (Department: 3752)

Fluid sprinkling, spraying, and diffusing

Flow deflecting or rotation controlling means

Fluid rotation inducing means upstream of outlet

C239S493000, C239S496000, C239S492000, C239S497000, C239S463000

Reexamination Certificate

active

06241165

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention concerns nozzles for spraying liquids, which can be used in the most diverse applications, such as spray pumps, evaporators, combustion burner nozzles and internal combustion engine injectors, for example.
The invention applies more particularly to spray nozzles in which the liquid to be sprayed is fed into a central swirl chamber via lateral fluid inlet passages injecting the liquid tangentially, the liquid then leaving the central swirl chamber through a coaxial outlet passage.
Spray nozzles with a central swirl chamber generally spray liquids well.
Usually they are made of metal, by conventional machining processes, and comprise a hollow nozzle body, with an external peripheral wall having a longitudinal axis, and a radial anterior external wall incorporating an axial outlet hole for the outflow of the fluid. The central swirl chamber is delimited by a peripheral wall with a shape of revolution about a longitudinal axis, an anterior wall with a coaxial outlet passage, and a posterior wall. The anterior wall with the coaxial outlet passage is formed by said radial anterior external wall, which is perpendicular to the longitudinal axis. At least one lateral fluid inlet passage is provided in the peripheral wall, opening into the central swirl chamber, and shaped to suit the inlet flow of fluid and to inject the fluid tangentially into the central swirl chamber.
In use, the spray nozzles produce an outflow in the form of a liquid spray in the form of fine droplets, the flow being generally conical in the direction of the longitudinal axis, and the droplets being distributed at random within the cone.
In machining metal spray nozzles on an industrial scale, there is a broad spread of the main outflow parameters, namely the size of the droplets, the outlet angle value, and the spectrum of distribution of the droplets within the cone.
The spread in the outflow characteristics leads to considerable difficulties in using the spray nozzles. In particular, this leads to a random increase in the level of carbon monoxide and in the level of hydrocarbons in the exhaust gas, a reduction in combustion efficiency, and soiling of heat exchange walls around the combustion area.
The spreads of the liquid outflow parameters are due to the spread of the dimensions of the fluid inlet passages and, most importantly, the dimensions of the central swirl chamber. It is not economically feasible to reduce the spreads of these dimensions with conventional manufacturing methods which machine the metal parts constituting the prior art spray nozzles, because this would require very accurate machining and this cannot be done economically, especially in the case of small spray nozzles.
Document CH-421 009 A proposes to facilitate manufacture by making the peripheral and anterior walls of the swirl chamber, the coaxial outlet passage and the lateral fluid inlet passages in the form of posterior openings and grooves in an anterior plate fastened into a hollow nozzle body and pressed against an anterior external wall by a posterior core.
The anterior plate and the posterior core are both retained laterally and independently of each other by the peripheral wall of the nozzle body.
This structure with an attached anterior plate does not lend itself to economic and reproducible mass production of spray nozzles including a coaxial posterior opening in the posterior core extending the swirl chamber towards the rear.
A coaxial posterior opening of this kind can in particular be beneficial for stabilizing the spray cone at the nozzle outlet.
STATEMENT OF THE INVENTION
The problem addressed by the present invention is that of designing a new spray nozzle structure with a central swirl chamber that can be manufactured economically and accurately using high-precision techniques, so that the fluid inlet passages and the central swirl chamber dimensions are precise and reproducible, and so that a posterior swirl chamber opening is precisely centered.
The invention aims in particular to provide small spray nozzles of this kind, in which the fluid inlet passages and the central swirl chamber are of small size, in such a way that the necessary dimensional accuracy leads to absolute accuracies in the order of only a few microns.
Another problem, addressed by some embodiments, of the invention is that of avoiding the risks of damage to the spray nozzle if the fluid contained in the spray nozzle freezes.
To achieve the above and other objects, the invention provides a spray nozzle having:
a hollow nozzle body with a peripheral external wall having a longitudinal axis and a radial anterior external wall incorporating an axial outlet hole,
a central swirl chamber delimited by a peripheral wall with a shape of revolution about the longitudinal axis, an anterior wall incorporating a coaxial outlet passage smaller than the axial outlet hole, and a posterior wall,
at least one lateral fluid inlet passage in the peripheral wall, opening into the central swirl chamber and shaped to inject the fluid tangentially into the central swirl chamber,
an anterior plate fastened into the hollow nozzle body and bearing against the radial anterior external wall, incorporating posterior openings and grooves forming the peripheral and anterior walls at least of the central swirl chamber, the coaxial outlet passage and said at least one lateral fluid inlet passage, and
a posterior core fitted into the hollow nozzle body, and having peripheral fluid feed passages, and an anterior face pushing said at least one attached anterior plate towards said radial anterior external wall of the hollow nozzle body,
and in which:
the posterior core comprises a posterior core body retained in the hollow nozzle body by fixing means, and a posterior plate held in position by the posterior core body and bearing axially against the anterior plate to form the posterior wall of the central swirl chamber and to delimit said at least one fluid inlet passage towards the rear,
the anterior and posterior plates are provided with relative centering means for centering the plates relative to each other about the longitudinal axis,
the posterior plate comprises, along the longitudinal axis, a posterior recess with a smaller cross section than the central swirl chamber, and
at least one of the anterior and posterior plates is mounted with radial clearance in the hollow nozzle body.
One option is for the relative centering means for the plates to be formed on their respective front bearing surfaces.
The relative centering means for the plates preferably comprise a posterior peripheral rib on the anterior plate in which the periphery of the posterior plate engages.


REFERENCES:
patent: 1183393 (1916-05-01), Merrell
patent: 2378348 (1945-06-01), Wilmes et al.
patent: 2753218 (1956-07-01), Kelsey et al.
patent: 421009 (1964-11-01), None

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