Rotating spray nozzle with controlled braking action

Details Rotating spray nozzle with controlled braking action Rotating spray nozzle with controlled braking action

1997-09-08

2001-02-27

Weldon, Kevin (Department: 1734)

Fluid sprinkling, spraying, and diffusing

Distributor continuously moves relative to support during...

Spray fluid motor drive means

Reexamination Certificate

active

06193169

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to a rotating nozzle for spraying one or more jets of water or other fluid.
BACKGROUND OF THE INVENTION
In the cleaning of walls such as a container wall, it is necessary to use a liquid jet which impinges on the wall with a comparatively high jet force. All parts of the wall must be reached with the jet in order to achieve the desired cleaning effect. In the case of, for example, a cylindrical container, it is advantageous to use a rotating nozzle head which itself sprays the jet over the entire inner circumferential surface of the container. The cleaning fluid that flows through the nozzle is used to rotate the nozzle head.
To be effective, a rotating nozzle head must run slowly in order to insure thorough cleaning of the container wall rather than mere wetting of the wall. High speed nozzles produce a spray jet of fine particles which are retarded by ambient atmosphere and do not impinge on the container wall with sufficient velocity to ensure effective cleaning of the wall. Moreover, it is desirable that the nozzle head rotate at a speed that is substantially independent of the pressure of the cleaning fluid and especially when the cleaning fluid is foam. In order to provide a slowly rotating nozzle head, it is a known practice to use the cleaning fluid to drive a turbine which acts through a gear to rotate the nozzle head. The requirement for a gear makes the nozzle structure relatively expensive.
SUMMARY OF THE INVENTION
The general aim of the present invention is to provide a comparatively low cost rotating nozzle in which the nozzle head is driven directly and without a gear at a low rotational speed and in which the speed of the head in a predetermined pressure range remains relatively constant.
In part, the foregoing is achieved through the provision of a rotating nozzle having an axial thrust bearing with relatively slidable surfaces which act simultaneously as a friction brake, the braking action of which is controlled by the fluid pressure. Although it is not fully known as to how the friction brake automatically limits the rotational speed, it is possible that, at low pressures, a liquid friction exists in the axial gap of the two bearing surfaces of the axial bearing as a result of the liquid flowing through the nozzle. At increasing pressures, the friction is believed to convert into a dry friction by reason of increased pressure forces acting on upstream surfaces of the turbine that act to increase braking action of the axial bearing surfaces of the thrust bearing. Thus, the coefficient of friction changes in dependence on pressure and, up to an operating pressure of 0.5 bar, the rotational speed of the turbine and the nozzle head increases approximately proportionally to the pressure, there being achieved depending on construction of the nozzle a rotational speed up to about 35 r.p.m. At about 0.5 bar, the proportionality between rotational speed and fluid pressure ends. Above such pressure, the rotational speed actually begins to decline, the decrease in the rotational speed also being dependent on construction parameters of the nozzle.
In order not to impair the desired braking effect by the axial thrust bearing, no appreciable sealing is provided at the bearing except for the sealing effected by the bearing itself. Automatic starting of the rotating nozzle head may be achieved when the coefficient of friction in the axial thrust bearing is low and lies in the range between 0.05 and 0.15. Such coefficients of friction can be achieved if one or both axial bearing surfaces contain, for example, PTFE or a material with a comparable coefficient of friction.
In order to make the turbine efficient, an injector is located on the inlet side of the turbine. Inclined passages in the injector generate a generally tangential jet flow into the turbine. A very simple turbine is provided in the form of a cylindrical plate, in the outer circumferential surface of which grooves are formed to define passages. To enable the rotating nozzle head to start of itself and run with uniform angular velocity, the number of passages in the injector is aliquot of the number of passages in the turbine.
These and other objects and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.


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patent: 680684 (1969-02-01), None
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patent: 42 25 421 A1 (1993-02-01), None
patent: 8150 (1904-05-01), None

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