CLEANING NOZZLE

Abstract

The cleaning nozzle according to the invention having a nozzle body (100) and a nozzle head (104) arranged on a shaft (106) rotatably seated on said nozzle body, and having a cavity (107), which extends in axial direction in said nozzle body (100) and which is connected with a pressurized water supply (102), by means of which cavity pressurized water supplied via the pressurized water supply (102) is guided to the nozzle head (104) and is discharged to the outside in said nozzle head (104) by at least one nozzle orifice (118), is formed especially by a friction brake comprising at least two disc elements (108, 110) that are in mechanical contact one with the other in the axial direction for restricting the rotational motion of the shaft (106).

Description

In the drawings

FIG. 1 shows a sectional view of a corresponding cleaning nozzle according to the prior art;

FIG. 2 shows a corresponding sectional view of a preferred embodiment of the cleaning nozzle according to the invention; and

FIG. 3 shows an enlarged exploded view of the embodiment of the friction brake illustrated by the sectional view of FIG. 2.

FIG. 1 shows a cleaning nozzle 1 of the kind described in EP 0 645 191 A1. The nozzle comprises a substantially cylindrical housing 2 provided with an outer thread 3 on its rear end. The housing 2 encloses a continuously cylindrical inner space 4 which transitions, at the end face 5 of the housing 2, into a bore 6 extending coaxially to the housing. Fitted in the coaxial bore 6 is a flange bushing 7, made from PTFE (polytetrafluoroethylene), which has its flange located in the inner space 4. Further, the nozzle comprises a fluid inlet 11 formed by a bore with an inner thread 12 that extends through the bottom of a cap nut 9.

A turbine 13, rotating inside the cylindrical inner space 4, is configured as a cylindrical disc and comprises turbine blades not visible in the described drawing. At its end 15, the disc forming the turbine 13 terminates without interruption in a turbine shaft 17.

Pressurized water supplied through the fluid inlet 11 is guided via oblique bores 32 into a pre-chamber 31 preceding the turbine 13, whereby the turbine 13 is set into rotation. The pressurized water then reaches a pressurized water chamber 33. From the pressurized water chamber 33, the pressurized water proceeds to a pressurized water channel 34, extending centrally in the turbine shaft 17, and finally, via the pressurized water channel 34, to a pressurized water discharge chamber 42 arranged in a nozzle head 37 from where the pressurized water is finally discharged in radially outward direction via nozzle-shaped fluid outlets 41, 44.

The axial forces of the turbine occurring during operation of the known cleaning nozzle 1 are absorbed by an axial bearing 23 the bearing surfaces of which are formed, respectively, by a flat inner end face of a flange 8 and by a ring 25 which is slipped onto the turbine shaft 17 and up to a shoulder 19.

A preferred embodiment of the cleaning nozzle according to the invention will now be described with reference to FIG. 2. In the present embodiment, the cleaning nozzle has a three-piece design, being composed of a central nozzle body 100, a pressurized water connection piece 102 and a nozzle head 104 arranged on a rotating shaft 106. In the arrangement of the present embodiment, the central nozzle body 100 and the pressurized water connection piece 102 are screwed together (detachably) at points not visible in FIG. 2. However, the two parts may also be connected, either detachably or non-detachably, in any other manner known to the man of the art, for example by welding. Correspondingly, the nozzle head 104 and the shaft 106 are screwed together in the present case at points likewise not visible in FIG. 2 although they might be connected, detachable or non-detachably, in any other way known to the man of the art, for example by welding. The shaft 106 as such is, however, rotatably seated in the central nozzle body 100, its rotary axis extending in axial direction.

Formed in the shaft 106, at the level of the central axis, is an axially extending cylindrical hollow space 107 by means of which pressurized water is supplied to the nozzle head 104 through a pressurized water supply opening 113 provided on the pressurized water connection piece 102, and from there to the outside via laterally provided nozzle orifices 118 and a central nozzle orifice 120 formed at the level of the central axis. The lateral nozzle orifices 118 simultaneously produce, due to the before-mentioned repulsion effect, on the one hand a cleaning effect acting substantially in a radially outward direction and, on the other hand, a rotary movement of the shaft 106. In contrast, the axially central nozzle orifice of the present embodiment only serves to produce a cleaning effect on the front of the nozzle head 104. The supply of the pressurized water from the cavity 107 to the said nozzle orifices 118, 120 is effected via corresponding pressurized water channels 116, 119 provided in the nozzle head 104.

The cleaning nozzle illustrated in FIG. 1 is provided especially with a friction brake of the kind described at the outset for reducing the rotary movement of the shaft 106 or of the nozzle head 104 arranged on the shaft 106, respectively. In the illustrated embodiment, the friction brake consists of a first disc element 108, seated in a recess or cutout in the shaft 106, which recess is arranged concentrically relative to the rotary shaft 106, and of a second disc element 110 being in mechanical contact with the first disc element 108 and being embedded in a likewise concentric circular recess or cutout in a sleeve body 111.

With respect to their function, the two disc elements 108, 110 simultaneously form sliding bearings for the shaft 106 and are preferably made from a ceramic material. Due to the surface roughness of that material, an optimum friction coefficient is obtained during rotation of the two ceramic discs 108, 110. Further, the two disc elements 108, 110 are frictionally embedded in the said recesses or cutouts whereby any movement or rotation of the elements in the recesses during rotation is prevented so that the maximum frictional force will be available at the point of contact between the two disc elements 108, 110 during rotation of the shaft 106.

The sleeve body 111 is sealed relative to the pressurized water connection piece 102 by an 0 ring 112 in order to prevent, as far as possible, any pressurized water from being pressed out from between the outer wall of the sleeve body 111 and the opposite inner wall of the pressurized water connection piece 102. In case any “excess” pressurized water should still be pressed out—a condition that never can be fully excluded—such water will be carried off by a plurality of pressurized water discharge channels 114 arranged along a concentric circle (FIG. 3). At the same time, the O ring 112 prevents the braking effect of the two disc elements 108, 110 from becoming excessively high.

According to the invention, the friction produced by the friction brake 108,110 during rotation of the shaft 106, which counteracts the rotary movement, is especially produced or reinforced by the fact that on its way through the pressurized water supply opening 113 and the cavity 107 in the area of the annular edge of step 115 of the sleeve body 111, projecting beyond the inner wall of the cavity 107, the pressurized water will “hit against” or form slight turbulences against such edge, thereby increasing the contact pressure between the two disc elements 108, 110. Consequently, the increase of the contact pressure can be adjusted precisely and continuously by varying the width of the edge 115 in the radial direction.

As has been described before, the nozzle head 104 is driven via the jet-propelled nozzle orifices 118, 120. Braking the rotary movement of the nozzle 104 is effected inside a hollow thrust pad to which a flow of pressurized water is supplied and which is pressed against the shaft end of the drive shaft by a cylinder. The friction moment thereby obtained counteracts the torque of the rotor head, thereby reducing its speed. The brake bodies used consist of two ceramic discs resting flat one against the other so that only minor quantities of leakage water will be permitted to escape during rotation which means that the discs simultaneously act as sealing elements. Accordingly, the system can do without any high-pressure lip seal of the kind required by the system of the prior art.

The two ceramic discs 108, 110 act as seal and simultaneously as brake. This allows the desired speed to be precisely and finely adjusted in the system of the invention via a pressurized water flow guided through the brake nozzle orifices while maintaining the relatively slow rotation of the nozzle head over a wide pressure range of approximately 70 to 150 bars, without any loss in function.

The two ceramic discs 108, 110 may be formed as one-piece or as multi-piece units. A spring biasing means provided for the ceramic discs 108, 100 effectively prevents any penetration of dirt. The present rounded rectangular shape prevents any torsional movement of the one ceramic disc so that the latter remains fixed against rotation relative to the nozzle housing.

As regards the surfaces of the two ceramic discs 108, 110 that are in contact one with the other, an arrangement is preferred where the one surface is relatively smooth while the other surface is relatively rough so that static friction between the two surfaces will not become excessively high and sliding by jerks of the two ceramic discs 108, 110, one relative to the other, will be effectively prevented.

As can be further seen in FIG. 2, the pressurized water is supplied to the nozzle head 104 via a radially central pressurized water supply opening 113, i.e. along a straight path. In the case of the nozzle illustrated in FIG. 1, in contrast, the pressurized water is introduced at the inlet via oblique bores in order to set the turbine into rotation. To say it in other words, the water enters the shaft above the turbine only, in the reinforced part of the shaft, via oblique braking bores, at an angle of approximately 90°.

In the case of the cleaning nozzle according to the invention, the incoming pressurized water flows through the two ceramic discs 108, 110 directly, whereas in the case of the nozzle described in FIG. 1, the pressurized water flows through the shaft only while the two sliding bearings are arranged outside the shaft. It is that direct “contact” with the pressurized water that finally permits the described precise adjustment of the friction effect.

The high flow rate of the pressurized water further results in the known “water-jet blast effect”, i.e. a partial vacuum dependent on the flow rate, due to which a suction effect is additionally produced between the two ceramic discs 108, 110. That suction effect, which acts to increase the friction effect, is missing completely in the cleaning nozzle illustrated in FIG. 1 since, as has been mentioned before, the sliding bearings of that nozzle are not even passed by the pressurized water.

FIG. 3 once more shows the pressurized water connection piece 102 illustrated in FIG. 2 and the different parts of the friction brake according to the invention, likewise illustrated in FIG. 2, in an enlarged exploded view. As can be seen in particular in FIG. 3, the sleeve body 111 described above has a laterally flattened shape in a transition area 200 and engages a recess 202 of a corresponding non-circular shape in the pressurized water connection piece 102. That flattened portion 200 prevents the sleeve body 111 from rotating with the two ceramic discs 108,110 during relative rotation of the two discs, which otherwise would reduce the friction force between the two ceramic discs 108, 110.

The end portion 204 of the sleeve body 111, being likewise contracted in the said transition area 200, engages the pressurized water supply opening, engages the pressurized water connection piece 102 by friction, forming in this position the annular edge that has been described above in detail and which likewise influences the contact pressure between the two ceramic discs 108, 110. Further, the before-mentioned O ring 112 is indicated in FIG. 3, as are the openings of the concentric pressurized water discharge channels 114.

Claims

1. A cleaning nozzle having a nozzle body and a nozzle head arranged on a shaft rotatably seated on said nozzle body, and having a cavity, which extends substantially in axial direction in said nozzle body and which is connected with a pressurized water connection supply, by means of which cavity pressurized water supplied via the pressurized water supply is guided to the nozzle head and is discharged from the nozzle head to the outside by at least one nozzle orifice, characterized by at least two disc elements, arranged in the area of the cavity and moving substantially into mechanical contact one with the other in the direction of flow of the pressurized water, which elements form a friction brake that acts to restrict the rotational motion of the shaft.

2. The cleaning nozzle as defined in claim 1, characterized in that the pressurized water is emitted tangentially in the circumferential direction of the nozzle head, from the at least one nozzle orifice, in order to thereby exert a torque on the shaft.

3. The cleaning nozzle as defined in claim 1, characterized in that the first one of the at least two disc elements is embedded in a recess of the shaft which is arranged concentrically relative to the rotary axis of the shaft.

4. The cleaning nozzle as defined in claim 1, characterized in that the second one of the at least two disc elements is embedded together with the first disc element in a concentrically arranged circular recess of a sleeve body.

5. The cleaning nozzle as defined in claim 3, characterized in that the first one and/or the second one of the at least two disc elements is/are embedded by friction.

6. The cleaning nozzle as defined in claim 1, characterized in that the at least two disc elements simultaneously act as sliding bearings for the shaft.

7. The cleaning nozzle as defined in claim 1, characterized in that the one of the at least two disc elements has a relatively smooth surface, at least on the side of the contact surface of the two disc elements, and that the respective other disc element has a relatively rough surface, at least on the side of the contact surface of the two disc elements.

8. The cleaning nozzle as defined in claim 7, characterized in that the at least two disc elements are made from a ceramic material, preferably from Al2O3.

9. The cleaning nozzle as defined in claim 4, characterized in that the sleeve body is sealed relative to the nozzle body by a gasket.

10. The cleaning nozzle as defined in claim 4, characterized in that any pressurized water that may penetrate from between the sleeve body and the nozzle body is recycled via pressurized water discharge channels.

11. The cleaning nozzle as defined in claim 4, characterized in that the sleeve body forms an edge on the inside of the cavity, on which the pressurized water flowing through the cavity produces turbulences or vortexes whereby the contact pressure of the at least two disc elements is increased.

12. The cleaning nozzle as defined in claim 11, characterized in that the contact pressure between the at least two disc elements can be adjusted by varying the width of the edge.

13. The cleaning nozzle as defined in claim 1, characterized in that the at least two disc elements are of a one-piece or of a multi-piece design.

14. The cleaning nozzle as defined in claim 1, characterized in that the at least two disc elements are mechanically spring-biased one relative to the other.

15. The cleaning nozzle as defined in claim 1, characterized in that at least one of the at least two disc elements has a contour of the outer surface different from a circular shape.

16. The cleaning nozzle as defined in claim 2, characterized in that the first one of the at least two disc elements is embedded in a recess of the shaft which is arranged concentrically relative to the rotary axis of the shaft.

17. The cleaning nozzle as defined in claim 4, characterized in that the first one and/or the second one of the at least two disc elements is/are embedded by friction.