Abstract:
A rotor nozzle for a high-pressure cleaning appliance is provided. The rotor nozzle has a housing, which comprises at least one inlet opening tangentially, and which is provided in a front wall with a pan-shaped depression with a central opening. A nozzle body is arranged in the housing and supported with a spherical end in the pan-shaped depression. A longitudinal axis of the nozzle body is inclined to the longitudinal axis of the housing, it being possible for liquid in the housing to be caused to rotate about the longitudinal axis, and the nozzle body rotating together with the rotating liquid. In order to reduce flow losses in the rotor nozzle, without the operation of the rotor nozzle (in particular, start-up behavior of the nozzle body) being noticeably impaired, the nozzle body is provided with an outer contour deviating from the circular shape in a rear end area.

Description:
This application is a continuation of international application number PCT/EP2010/057080 filed on May 21, 2010 and claims the benefit of German application number 10 2009 023 647.3 filed on May 25, 2009. 
     The present disclosure relates to the subject matter disclosed in international application number PCT/EP2010/057080 of May 21, 2010 and German application number 10 2009 023 647.3 of May 25, 2009, which are incorporated herein by reference in their entirety and for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     The invention relates to a rotor nozzle for a high-pressure cleaning appliance with a housing, which comprises at least one inlet for a liquid opening tangentially into the housing, and which is provided in a front wall with a pan-shaped depression with a central opening, and with a nozzle body arranged in the housing, the nozzle body having a through-channel and being supported with a spherical end in the pan-shaped depression, and the longitudinal axis of the nozzle body being inclined to the longitudinal axis of the housing, it being possible for liquid in the housing to be caused to rotate about the longitudinal axis of the housing by the liquid flowing via the at least one inlet into the housing, and the nozzle body rotating together with the rotating liquid and in doing so bearing with a contact surface at its circumference against the inside wall of the housing. 
     Such rotor nozzles are known, for example, from DE 41 29 026 C1. With these a compact jet of liquid circulating on the surface of a cone can be generated, which, for example, for cleaning purposes can be directed onto a surface to be cleaned. For this purpose, the inlet of the housing can be connected to a high-pressure cleaning appliance, so that liquid under high pressure can be supplied to the housing. In the housing there is located a nozzle body, which is only mounted at one side on the pan-shaped depression and otherwise can move in the housing about the longitudinal axis of the housing. The nozzle body has a through-channel through which the liquid can pass through the depression of the housing, which has an opening. The longitudinal axis of the nozzle body is inclined in relation to the longitudinal axis of the housing. Owing to the liquid entering the housing tangentially, the nozzle body is pressed into the pan-shaped depression, which forms a bearing for the nozzle body, and, at the same time, the nozzle body is caused to rotate about the longitudinal axis of the housing. As a consequence of this, the exiting jet of liquid also describes the desired circular movement, so that a relatively large surface can be acted upon with liquid at a pressure comparable to spot jet nozzles. 
     The supplying of the liquid under pressure via the inlet opening tangentially into the housing ensures that liquid located in the housing is rotated about the longitudinal axis of the housing and the nozzle body is thereby also rotated about the longitudinal axis of the housing by a rotating liquid column forming inside the housing. The at least one tangential inlet does, however, form a flow resistance for the liquid, which results in flow losses. In order to reduce the flow resistance, the diameter of the at least one tangential inlet could be increased. However, this then has the consequence that the flow velocity of the liquid in the area of the at least one tangential inlet is reduced, and this, in turn, may have the consequence that the nozzle body cannot in all cases, be reliably caused to rotate about the longitudinal axis of the housing. In particular, the so-called “start-up behavior” of the nozzle body may be impaired. Start-up behavior is to be understood as initiation of the rotation of the nozzle body. Before liquid under pressure is supplied to the housing, the nozzle body is at rest relative to the inside wall of the housing, i.e., it is not yet executing a rotational movement about the longitudinal axis of the housing. When liquid under pressure is now supplied via the at least one tangential inlet, the static friction between the nozzle body and the inside wall of the housing must first be overcome in order to be able to cause the nozzle body to rotate. A relatively large initial frictional force must, therefore, first be overcome in order to move the nozzle body. When the nozzle body then executes a rotational movement, it is the sliding friction, which is usually smaller than the initial static friction, that is then responsible for the frictional behavior of the nozzle body at the inside wall of the housing. As a consequence of this, a lower force is required for maintaining a rotational movement of the nozzle body about the longitudinal axis of the housing than for initiating the movement. 
     If the flow cross section of the at least one tangential inlet is now increased, in order to reduce flow losses in the area of the inlet, the flow velocity of the liquid in the area of the inlet is thereby reduced, and this may, in turn, have the consequence that the force exerted by the liquid on the nozzle body is not sufficient to cause the nozzle body to rotate about the longitudinal axis of the housing. 
     The object of the present invention is to so develop a rotor nozzle of the kind mentioned at the outset that flow losses can be reduced in the area of the rotor nozzle without operation of the rotor nozzle, in particular, start-up behavior of the nozzle body, thereby being noticeably impaired. 
     SUMMARY OF THE INVENTION 
     This object is accomplished, in accordance with the invention, with a rotor nozzle of the generic kind in that the nozzle body has an outer contour deviating from the circular shape in a rear end area facing away from the front, spherical end. 
     Owing to the outer contour deviating from the circular shape in the rear end area of the nozzle body, a force by means of which the nozzle body is caused to rotate about the longitudinal axis of the housing can be transferred more effectively to the nozzle body by the liquid rotating in the housing. This, in turn, makes it possible to increase the flow cross section of the at least one inlet opening tangentially into the housing, without operation of the rotor nozzle and, in particular, start-up behavior of the nozzle body being thereby adversely affected. As a result of increasing the flow cross section of the at least one inlet, the flow velocity of the liquid is reduced in the area of the inlet, but owing to the outer contour deviating from the circular shape in the rear end area of the nozzle body, this does not impair its start-up behavior. Rather, the nozzle body is also reliably caused to rotate by the rotating liquid flowing in the housing about its longitudinal axis when the flow cross section of the at least one tangential inlet is increased. 
     Therefore, flow losses of the liquid in the area of the rotor nozzle can be reduced by the outer contour deviating from the circular shape in the rear end area of the nozzle body, and yet it is ensured that a cleaning jet under high pressure circulating on the surface of a cone can be reliably generated by the rotor nozzle. 
     It is advantageous for the area of the nozzle body with an outer contour deviating from the circular shape to extend right up to the rear end of the nozzle body. It has been found that this allows a particularly effective transfer of forces from the liquid rotating about the longitudinal axis of the housing to the nozzle body. 
     In its area with an outer contour deviating from the circular shape, the nozzle body is of non-circular configuration, which allows an effective transfer of forces from the rotating liquid to the nozzle body. For example, the nozzle body may have an oval shape or an undulating outer contour in this area. 
     A construction has proven particularly effective, in which the nozzle body is of angular configuration in the area with an outer contour deviating from the circular shape. In this area, the nozzle body may, for example, be of star-shaped configuration or in the form of a polygon, in particular, a square or a hexagon. The provision of edges in the area of the outer contour of the nozzle body enables a particularly efficient transfer of forces from the liquid rotating about the longitudinal axis of the housing to the nozzle body so that it follows the movement of the liquid and also rotates about the longitudinal axis of the housing. 
     In an advantageous configuration of the invention, the nozzle body has outwardly protruding ribs in its rear end area. The ribs impart an outer contour deviating from the circular shape to the nozzle body. 
     It is particularly advantageous for at least some ribs to extend in a radial plane in relation to the longitudinal axis of the nozzle body. The nozzle body may, for example, comprise a plurality of ribs distributed uniformly in the circumferential direction, which are each radially orientated. 
     As an alternative or supplement, it may be provided that at least some ribs extend perpendicularly to a radial plane in relation to the longitudinal axis of the nozzle body. Here radial plane is to be understood as a plane which is orientated in the radial direction in relation to the longitudinal axis of the nozzle body. 
     A plurality of ribs are preferably aligned parallel to one another. 
     The liquid rotating in the housing about its longitudinal axis may not only result in the nozzle body rotating in accordance with the liquid about the longitudinal axis of the housing. The liquid rotating about the longitudinal axis of the housing may, in particular, in the front area of the nozzle body with which it is mounted in the central, pan-shaped depression act as rotary drive for the nozzle body about its longitudinal axis, so that the nozzle body is caused to rotate inherently about its own longitudinal axis. The rotational movement of the nozzle body on the conical surface of the housing is superimposed by the inherent rotation about the longitudinal axis of the nozzle body. The inherent rotation results in the liquid jet that exits from the nozzle body also being made to rotate about its longitudinal axis. Once the liquid particles accelerated accordingly in the circumferential direction leave the nozzle body the liquid jet can, therefore, fan out. This may have the consequence that the cleaning effect of the liquid jet already deteriorates at a short distance from the nozzle body. To keep the inherent rotation of the nozzle body low, it is advantageous for the nozzle body to have a circular outer contour in its end area facing the front, spherical end. The transfer of forces from the liquid rotating in the housing to the nozzle body is reduced in the front area of the nozzle body by the circular outer contour. The risk of the liquid jet fanning out after leaving the nozzle body is thereby kept slight. In such a configuration, the nozzle body, therefore, has in its rear end area an outer contour deviating from the circular shape, which improves the start-up behavior of the nozzle body, and in its front end area, the nozzle body has a circular outer contour, which keeps the inherent rotation of the nozzle body about its own longitudinal axis low. 
     A cylindrical configuration of the nozzle body in its front end area is particularly advantageous. 
     Preferably, the area with a circular outer contour extends over at least half of the total length of the nozzle body. In such a configuration, the nozzle body has an outer contour deviating from the circular shape in its rear end area. However, this area extends, at most, over half of the total length of the nozzle body. 
     The area of the nozzle body with an outer contour deviating from the circular shape is preferably shorter in relation to the longitudinal axis of the nozzle body than the area with a circular outer contour. 
     In particular, it may be provided that the area with an outer contour deviating from the circular shape extends in the longitudinal direction of the nozzle body over an area of at most 40% of the total length of the nozzle body. It has been found that a particularly good start-up behavior with relatively low inherent rotation of the nozzle body is thereby achievable. 
     As mentioned at the outset, the nozzle body rotating about the longitudinal axis of the housing bears with a contact surface against the inside wall of the housing. The contact surface is preferably formed by an annular bead which is rotationally fixedly connected to the nozzle body. 
     It is expedient for the annular bead to be followed in the longitudinal direction of the nozzle body on both sides by areas with an outer contour deviating from the circular shape. In such a configuration, the annular bead is arranged at a distance from the rear end of the nozzle body, and the nozzle body has an outer contour deviating from the circular shape both in the area between the annual bead and the rear end of the nozzle body and in the area following the annular bead in the direction towards the front end of the nozzle body. A relatively large force can thereby be transferred by the liquid rotating about the longitudinal axis of the housing to the nozzle body on both sides of the annular bead, i.e., on both sides of the contact surface. It has been found that the start-up behavior of the nozzle body can thereby be improved. 
     The annular bead can be formed by, for example, an O-ring which is connected in a frictionally engaged manner to the nozzle body and is arranged in an annular groove surrounding the nozzle body. 
     The annular bead, in particular, the O-ring, is preferably made of a rubber-elastic material. 
     The inherent rotation of the nozzle body, explained above, about its own longitudinal axis can be reduced by the nozzle body comprising in its rear end area a mass element which increases the centrifugal force. Owing to its rotational movement about the longitudinal axis of the housing, the nozzle body is subject to a centrifugal force which acts upon the nozzle body perpendicularly to the longitudinal axis of the housing and presses the nozzle body against the inside wall of the housing. The inherent rotation of the nozzle body about its own longitudinal axis is thereby impeded. The centrifugal force acting on the nozzle body can be reinforced by the mass of the nozzle body being increased in its rear end area. It is, therefore, expedient for it to comprise a mass element, for example, a metal body, in this end area. 
     A spherical mass element, for example, a metal ball, in particular, a steel ball, is preferably used. 
     The liquid supplied to the housing via the at least one tangential inlet can only leave the housing by flowing through the through-channel of the nozzle body and then passing through the depression, which has an opening, at the front wall of the housing. The through-channel expediently extends in the axial direction through the nozzle body. The liquid can, therefore, enter the through-channel at the rear end of the nozzle body and leave the through-channel at the front end of the nozzle body. It has been found that the cleaning effect of the rotor nozzle is improved by such a through-channel. The through-channel has a relatively large length. Turbulences in the flow of liquid are thereby calmed. Such turbulences can cause a fanning-out of the jet of liquid flowing out of the nozzle body. The risk of turbulences is reduced by the relatively large length of the through-channel. 
     It is particularly expedient for a flow straightener to be arranged in the through-channel as turbulences in the jet of liquid can thereby be calmed particularly effectively. The flow straightener may comprise walls which extend parallel to the longitudinal axis of the nozzle body and pass diametrically through the through-channel. In particular, it may be provided that the flow straightener comprises two walls extending perpendicularly to each other and parallel to the through-channel and passing diametrically through the through-channel. 
     A mass element which increases the centrifugal force and around which the liquid flows is expediently arranged in the rear end area of the through-channel. The mass element may be pressed into the through-channel. This facilitates assembly of the nozzle body. 
     It is particularly advantageous for a flow straightener which follows the mass element in the direction towards the front, spherical end of the nozzle body to be arranged in the through-channel. In such a configuration, the liquid can flow axially through the nozzle body, with it entering the through-channel at the rear end of the nozzle body and first flowing around the preferably spherical or cylindrical mass element. The liquid then flows through the flow straightener following the mass element in the direction towards the front end of the nozzle body. The flow straightener brings about a calming of the jet of liquid by turbulences in the jet of liquid being attenuated. A practically turbulence-free flow of liquid can be achieved, so that the risk of the jet of liquid fanning out as it leaves the nozzle body is particularly slight. 
     The following description of a preferred embodiment of the invention serves for a more detailed explanation in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a diagrammatical longitudinal section through a rotor nozzle in accordance with the invention with a housing in which a nozzle body is arranged; 
         FIG. 2  shows a side view of the nozzle body with the housing cut in the longitudinal direction; 
         FIG. 3  shows a sectional view along line  3 - 3  in  FIG. 1 ; and 
         FIG. 4  shows a sectional view along line  4 - 4  in  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A rotor nozzle  10  for a high-pressure cleaning appliance, not represented in the drawings, is shown diagrammatically in the drawings. The rotor nozzle  10  is screwed onto a jet pipe  12  of the high-pressure cleaning appliance. The jet pipe  12  is only partially reproduced in the drawings as it is known per se to the person skilled in the art. It comprises a pipe section  13 , at whose end, not shown in the drawings, facing away from the rotor nozzle  10 , the pressure hose of the high-pressure cleaning appliance can be connected in the usual manner, and also a connecting section  14  with an external thread  16  for releasable connection of the jet pipe  12  to the rotor nozzle  10 . 
     The rotor nozzle  10  comprises a housing  20  with a first housing part  21  and a second housing part  22 , which define an interior  24 . The first housing part  21  has a frustoconical front housing section  26  with a front wall  28  and a casing  30 , and a rear housing section  32 , which integrally adjoins the front housing section  26  and is of hollow-cylindrical configuration. It carries an internal thread  34  into which the connecting section  14  of the jet pipe  12  is screwed with its external thread  16 . Adjoining the internal thread  34  in the direction towards the front wall  28  is a cylindrical sealing section  36 , which continues into the substantially frustoconical interior  24  via a shoulder  40  which is directed radially inwardly in relation to the longitudinal axis  38  of the housing  20 . 
     The second housing part  22  is configured in the form of an end plate  42 , which delimits the interior  24  in the axial direction, and bears, on the one hand, against the shoulder  40  and, on the other hand, against the free end  44  of the jet pipe  12 . Adjoining the end plate  42  in the direction facing away from the front wall  28  is a sealing ring  46  which surrounds the jet pipe  12  in the circumferential direction and ensures a liquid-tight connection of the jet pipe  12  to the rotor nozzle  10 . 
     The end plate  42  comprises a plurality of, preferably four, tangential inlets  48  spaced equidistantly from one another in the circumferential direction, via which liquid supplied to the rotor nozzle  10  via the jet pipe  12  from a high-pressure cleaning appliance can enter the interior  24 . Owing to the tangential orientation of the inlets  48 , the liquid entering the interior  24  has a directional component orientated tangentially in relation to the longitudinal axis  38 . Liquid is thereby caused to rotate about the longitudinal axis  38  of the housing  20  in the interior  24 . 
     The front wall  28  of the front housing section  26  has a central opening  50 , which widens conically in the direction facing away from the end plate  42 . On the inside, the central opening  50  is surrounded by a pan-shaped bearing ring  52 , which carries on the outside a sealing ring  54  and is thereby sealed off from the front housing section  26 . 
     The spherical front end  56  of a nozzle body  60  is supported in the bearing ring  52 . The nozzle body  60  is of multipart configuration. It comprises a nozzle  62 , which forms the front end  56  of the nozzle body  60 , and a nozzle carrier  64  with a through-channel  68 , which extends in the axial direction along the longitudinal axis  66  of the nozzle body  60  and into which the nozzle  62  is pressed with a nozzle channel  70  which is aligned with the through-channel  68 . The through-channel  68  widens stepwise in its end area that faces away from the nozzle  62 . Pressed into the through-channel  68  in the area of the widening is a mass body in the form of a steel ball  72  which increases the centrifugal force. Adjoining the steel ball  72  in the through-channel  68  in the direction of the nozzle  62  is a flow straightener  74 , which comprises two walls  75 ,  76 , which extend perpendicularly to each other, run parallel to the longitudinal axis  66  of the nozzle body  60  and pass diametrically through the through-channel  68 . 
     Liquid can flow around the steel ball  72  in the through-channel  68 . After passing through the flow straightener  74  and the nozzle  62 , this liquid can, therefore, flow through the bearing ring  62  and the central opening  50  and thereby leave the rotor nozzle  10 . 
     The nozzle carrier  64  has a front peripheral area  78  with a circular outer contour and an adjoining rear peripheral area  80  with an outer contour that deviates from the circular shape. The outer contour of the rear peripheral area  80 , which deviates from the circular shape is formed by ribs  82 ,  83 ,  84 ,  85 ,  86 ,  87 ,  88 ,  89  which protrude from the outside of the nozzle carrier  64 . This will be clear, in particular, from  FIG. 3 . The ribs  82  and  86  are diametrically opposed and are each radially orientated in relation to the longitudinal axis  66  of the nozzle body  60 . In a corresponding manner, the ribs  84  and  88  are diametrically opposed and radially orientated. In contrast thereto, the ribs  83  and  89  are orientated in alignment with each other and parallel to the ribs  84  and  88 , and the ribs  85  and  87  are also orientated in alignment with each other and parallel to the ribs  84  and  88 . The spacing of the ribs  85  and  87  from the ribs  84  and  88 , respectively, is identical to the spacing of the ribs  83  and  89  from the ribs  84  and  88 , respectively. 
     At the level of the ribs  82  to  89 , the nozzle carrier  64  comprises in the rear peripheral area  80  an annular groove  91  which extends in the circumferential direction and in which an O-ring  92  is held in a frictionally engaged and thereby rotationally fixed manner. In relation to the longitudinal axis  66  of the nozzle body  60 , the O-ring protrudes in the radial direction beyond the ribs  82  to  89 . It forms a contact surface with which the nozzle body  60  can be made to bear against the inside wall  94  of the housing  20 . As will be clear, in particular, from  FIGS. 1 and 2 , the ribs  82  to  89  extend in the axial direction on either side of the O-ring  92 , and they run up to the rear end  96  of the nozzle body  60  that faces away from the front end  56 . 
     In the axial direction, the ribs  82  to  89  extend over less than half of the total length of the nozzle body  60 . In the illustrated embodiment, the length of the ribs  82  to  89  is less than 40% of the total length of the nozzle body  60 , for example, 30% to 35% of the total length. 
     As explained above, during operation, the rotor nozzle  10  is supplied with liquid under high pressure, for example, water, via the jet pipe  12  from a high-pressure cleaning appliance. The liquid flows via the tangential inlets  48  into the interior  24  of the housing  20  and can leave the interior via the through-channel  68 , the nozzle channel  70 , the bearing ring  52  and, following this, via the central opening  50 . During operation of the rotor nozzle  10 , the interior  24  is filled with liquid which is caused to rotate about the longitudinal axis  38  of the housing  20  by the liquid flowing in via the tangential inlets  48 . A liquid column rotating about the longitudinal axis  38  is thus formed in the interior  24 . The rotating liquid column takes along the nozzle body  60  supported with its spherical front end  56  in the bearing ring  52 , so that the nozzle body  60  also rotates about the longitudinal axis  38  of the housing  20 . The nozzle body  60  bears against the inside wall  94  of the housing  20  via the O-ring  92  held in a rotationally fixed manner on the nozzle body  60 . The longitudinal axis  66  of the nozzle body  60  is, therefore, at an inclination to the longitudinal axis  38  of the housing  20 . Owing to the inclination of the nozzle body  60 , the rear peripheral area  80  of the nozzle body  60  is located, at least at the level of the steel ball  72 , on only one side of the longitudinal axis  38  of the housing  20 , whereas the front peripheral area  78  extends both on the one side and on the opposite other side of the longitudinal axis  38 . This will be clear from  FIGS. 3 and 4 .  FIG. 3  shows a sectional view perpendicular to the longitudinal axis  38  of the housing  20  at the level of the steel ball  72 , and  FIG. 4  shows a sectional view perpendicular to the longitudinal axis  38  of the housing  20  approximately at the center of the front peripheral area  78 . 
     Owing to the inclination of the nozzle body  60  relative to the longitudinal axis  38  of the housing  20 , liquid flows in the same direction of flow around the rear peripheral area  80  at the level of the steel ball both on its radial outer side  98  in relation to the longitudinal axis  38  and on its radial inner side  99  in relation to the longitudinal axis  38 . The velocity vectors of the liquid flowing around the rear peripheral area  80  at the level of the steel ball  72  are indicated by arrows  101  and  102  in  FIG. 3 . Arrow  101  shows the velocity vector of the liquid flowing around the rear peripheral area  80  on the radial outer side  98 , and arrow  102  shows the velocity vector of the liquid flowing around the rear peripheral area  80  on the radial inner side  99 . On the radial outer side  98 , the liquid has a higher velocity than on the radial inner side, but the direction of the velocities coincides. The consequence of this is that in the rear peripheral area  80 , which is characterized by an outer contour deviating from the circular shape, a considerable force can be transferred to the nozzle body  60  by the liquid column rotating about the longitudinal axis  38  of the housing  20 , so that the nozzle body  60  follows the rotational movement of the liquid column about the longitudinal axis  38 . 
       FIG. 4  shows the flow conditions of the liquid flowing around the nozzle body  60 , which prevail in the front peripheral area  78 . The front peripheral area  78  is at a relatively short distance from the bearing ring  52 . In spite of its inclination to the longitudinal axis  38 , the nozzle body  60  therefore has on either side of the longitudinal axis  38  peripheral areas around each of which liquid rotating about the longitudinal axis  38  flows. Arrow  104  symbolizes the velocity vector of the liquid which flows around the front peripheral area  78  on a first side, and arrow  105  symbolizes the velocity vector of the liquid which flows around the front peripheral area  78  on the second side opposite the first side. It is evident that the velocity vectors  104  and  105  are opposed to each other. The liquid flowing around the nozzle body  60  in the front peripheral area  78 , therefore, has the tendency to cause the nozzle body  60  to perform an inherent rotation about its own longitudinal axis  66 . However, since the front peripheral area  78  has, in contrast to the rear peripheral area  80 , a circular outer contour, only a relatively low force is transferred to the nozzle body  60  by the liquid rotating about the longitudinal axis  38  of the housing  20  in the front peripheral area  78 . The nozzle body  60 , therefore, has a relatively low inherent rotation. However, since it is acted upon in the rear peripheral area  80  by the liquid rotating about the longitudinal axis  38  on both the inside and the outside by forces in the same direction, which owing to the non-circular outer contour in this area are of a considerable size, the nozzle body  60  is reliably set in rotational movement about the longitudinal axis  38  without these forces bringing about an inherent rotation of the nozzle body  60 . 
     The rotational movement of the nozzle body  60  about the longitudinal axis  38  results in a compact cleaning jet, which circulates on the surface of a cone, exiting from the housing  20  of the rotor nozzle  10 . This compact cleaning jet is particularly suitable for cleaning purposes.