Abstract:
A tank-cleaning device, having a housing ( 1 ) insertable into an opening of a tank, which housing has a rotationally fixed housing part ( 2 ) communicating with an ink for the cleaning fluid and a nozzle holder ( 4 ) rotatable relative to the rotationally fixed housing part ( 2 ) about a first pivot axis ( 5 ), and having at least one nozzle assembly with four nozzles ( 8, 9, 10, 11 ) that is disposed on the nozzle holder ( 4 ) rotatably about a second pivot axis ( 7 ), while having a simple structure, enables thorough cleaning of tanks with narrow tank openings, if two nozzles at a time ( 8, 9; 10, 11 ) of the nozzle assembly ( 6 ) are disposed at an acute angle ( 12 ) to one another in the form of respective V-formations ( 13, 14 ), and the two V-formations ( 13, 14 ) have essentially opposed directions ( 15 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a tank-cleaning device, having a housing insertable into an opening of a tank, which housing has a rotationally fixed housing part communicating with an ink for the cleaning fluid and a nozzle holder rotatable relative to the rotationally fixed housing part about a first pivot axis, and having at least one nozzle assembly with four nozzles that is disposed on the nozzle holder rotatably about a second pivot axis. 
     A similar tank-cleaning device is known from European Patent Disclosure EP 0 430 659 A2. This known tank-cleaning device has a slender housing, which can be introduced even into a narrow tank opening. The nozzle assembly has only two nozzles, which are disposed at an angle of 180° to one another. When the housing is introduced into a narrow tank opening, the nozzle assembly is rotated in such a way that the common axis of the two nozzles is parallel to the longitudinal axis of the housing. The tank opening therefore has to have an only slightly greater diameter than the slender housing of the tank-cleaning device. A small tank opening can advantageously be manufactured much more economically than a large one. 
     On the inside surface of the tank, during the cleaning operation, the two nozzles create a certain netlike spray pattern, which at a fixed, predetermined ratio of the two rotary motions about the two aforementioned pivot axes is always repeated after a certain number of rotations and has a fixed “mesh width”. The paths traced on the inside surface of the tank by the fluid streams come to have a fixed density, which cannot be increased even by providing a long cleaning period, since the fluid streams always travel along the same paths. 
     In other known devices, the cleaning density has therefore been reduced by the disposition of four nozzles instead of two nozzles. The four nozzles in the known nozzle assemblies are always disposed at uniform angular intervals of 90° each from one another. The reason for this is that in the known tank-cleaning devices, the nozzles rotate uniformly about a typically horizontally disposed pivot axis, while the entire nozzle assembly rotates uniformly about a typically vertical pivot axis. Given the equal 90° angular spacings of the nozzles, the result is accordingly a uniform spray pattern without major gaps on the inside surface of the tank. 
     The known nozzle assemblies with four nozzles have the disadvantage, however, that when they are introduced into a narrow tank opening, not all the nozzle axes can be adjusted parallel to the longitudinal axis of the housing anymore, or at least not unless further complicated engineering provisions are made. With very narrow tank openings, one is therefore forced to shorten the nozzle length, but this leads to a poorer quality of the fluid stream and less-effective cleaning, with poorer outcomes of cleaning. This means in turn, however, that so far, there has been no tank-cleaning device with four nozzles that fits through a narrow tank opening and nevertheless furnishes a fluid stream that attains effective cleaning. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is therefore to disclose a tank-cleaning device which with a simple structure permits thorough cleaning of tanks with narrow tank openings. 
     This object is attained according to the invention in that two nozzles at a time of the nozzle assembly are disposed at an acute angle to one another in the form of respective V-formations, and the two V-formations have essentially opposed directions. 
     Surprisingly, it has been found that with the arrangement of nozzles in V-formations that form an acute angle, in accordance with the invention, a uniform spray pattern without major gaps can be created. If this nozzle assembly is rotated such that one V-formation points upward and the other points downward, then the longer dimension of the nozzle assembly is oriented in the direction of the longitudinal axis of the housing. The minimum required diameter of the tank opening is then determined only by the housing width and by the slenderer dimension of the nozzle assembly. 
     In a preferred embodiment, it is provided that the rotation of the nozzle holder about the first pivot axis and the rotation of the nozzle assembly about the second pivot axis are mechanically coupled to one another and have a fixed ratio to one another, so that the spray pattern repeats after a certain number of revolutions, and that the acute angles of the V-formations are adapted to the ratio of the two rotations with a view to a uniform spray pattern. If the ratio of the rotations is fixed, then by a skilled selection of the acute angle a uniform spray pattern without major gaps can be created that does not substantially differ from the spray pattern of known tank-cleaning devices that have four nozzles each disposed at right angles. 
     If the first pivot axis coincides with the longitudinal axis of the housing and is disposed perpendicular to the second pivot axis, and if the ratio of the two rotations is 45:43, then with a view to a uniform spray pattern it is optimal that the acute angles of the V-formations amount to approximately 40°. With this arrangement of the pivot axes, uniform rotary motions can be generated by simple means. It can be calculated that at the aforementioned ratio of the two rotations, the following angles between the nozzles can be considered for attaining a uniform spray pattern: 90.00°; 81.63°; 73.26°; 64.88°; 56.51°; 48.14°; 39.77°; 31.40°; 23.02°; 14.65°; and 6.28°. The angle of 39.77° chosen here, or in round numbers 40°, represents an advantageous compromise with a view to a uniformly dense spray pattern with the smallest possible tank opening. 
     The provision that the two V-formations are disposed symmetrically to one another, so that two nozzles at a time point in opposite directions also contributes to the uniformity of the spray pattern. 
     If the two V-formations are disposed offset from one another, so that their pointed tips are each radially spaced apart from the second pivot axis, and the connecting line between the two pointed tips is substantially perpendicular to the angle bisector of the two acute angles, then the nozzles can be embodied advantageously long while optimally utilizing the little installation space available, so as to improve the quality of the fluid stream and the effectiveness of the cleaning. 
     If a turbine and a gear for driving the rotatable nozzle assembly are disposed in the elongated and slender rotationally fixed housing part in such a way that the cleaning fluid flowing in under pressure from the ink flows through the housing and drives the turbine before it emerges from the nozzles, then a slender device is obtained which is suitable for introduction into narrow tank openings and includes a simple drive mechanism for the two rotary motions, so as to assure thorough, uniform cleaning of the inside surfaces of the tank. 
     The invention can be improved still further in that an angular play of approximately 180° is provided between an element that drives the rotary motion of the nozzle assembly about the second pivot axis and the drive shaft of the nozzle assembly. As a result, in the range of the angular play, an alignment of the nozzle assembly longitudinally of the housing is made possible from any arbitrary rotary position, without having to activate the rotational drive mechanism. It is therefore possible for a nozzle assembly that may not be positioned correctly to be aligned by hand for insertion into a narrow tank opening, without having to rotate the drive elements as well, and without unnecessarily using up the cleaning fluid otherwise required for drive purposes. 
     In an advantageous feature of the aforementioned angular play, the drive shaft is provided with a pin, which protrudes radially past its outside diameter and engages a recess, extending in the direction of rotation over an angular range of 180°, in the hub region of a cone wheel supported rotatably on the drive shaft. 
     Another advantageous feature provides that a platelike baffle connected to the drive shaft in a manner fixed against relative rotation, in the hub region, has a first protrusion protruding axially inward and extending in the direction of rotation over an angular range of 90°; that a cone wheel rotatably supported on the drive shaft, in the hub region, has a second protrusion protruding axially outward, counter to the first protrusion, projecting in the same axial region as the first protrusion and extending in the direction of rotation over an angular range of 90°, so that the relative rotation between the platelike baffle and the cone wheel is limited to an angular range of 180° by the protrusions stopping against one another in the direction of rotation. The protrusions can be integrally molded in a simple way during production, in particular simultaneously with the casting of the cone wheel and baffle, with requiring further work steps such as inserting a pin into the drive shaft. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further advantages and details of the invention will become apparent from ensuing description of an exemplary embodiment in conjunction with the drawings. 
     Individually, the drawings show the following: 
     FIG. 1, a tank-cleaning device according to the invention in a plan view; 
     FIG. 2, a side view of the same tank-cleaning device; 
     FIG. 3, a sectional view of the same tank-cleaning device; 
     FIG. 4, a detail of a tank-cleaning device of the invention in a further version; 
     FIG. 5, a spray pattern produced with the tank cleaning device according to the invention; 
     FIG. 6, a detail showing the spray patterns of tank- cleaning devices having four nozzles and two nozzles, compared directly with one another. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The tank-cleaning device shown in the drawings comprises a housing  1 , which can be introduced into a narrow tank opening, not shown, and therefore has a slender shape. The housing a rotationally fixed housing part  2 , which on its top has an infeed opening  3  for connection of a source, not shown, for the cleaning fluid. The housing  1  also has a nozzle holder  4 , which is rotatable about a first pivot axis  5  relative to the rotationally fixed housing part  2 . A nozzle assembly  6  is supported on the nozzle holder  4  in a manner rotatable about a second pivot axis  7 . 
     The nozzle assembly  6  has four nozzles  8 ,  9 ,  10 ,  11 , of which two at a time, that is,  8 ,  9  on the one hand and  10 ,  11  on the other, are disposed at an acute angle  12  of approximately 40° from one another to form V-formations  13  and  14 , respectively. The two V-formations  13 ,  14  are disposed relative to one another such that they point in opposite directions  15 . This creates a nozzle assembly  4  that has a greater length in the directions  15  than transversely to these directions  15 . 
     If the nozzle assembly  4  is now aligned as shown in the drawings, that is, with the directions  15  parallel to the longitudinal direction of the housing  1 , then the tank-cleaning device can be introduced into even very narrow tank openings. 
     The two V-formations  13 ,  14  are disposed symmetrically to one another; the nozzles  9  and  10  point in opposite directions  15 , on the one hand, while the nozzles  8  and  11  also point in corresponding opposed directions. As best seen from FIG. 1, the V-formations  13 ,  14  are also offset from one another, so that their pointed tips  16 ,  17  are spaced apart from the second pivot axis  7 . The connecting line  18  between the two pointed tips  16 ,  17  is approximately perpendicular to the respective angle bisector  19 ,  20  of the two acute angles  12 . It is understood that to improve the compactness of the nozzle assembly  4 , the V-formations  13 ,  14  can also be offset in some other way than in the exemplary embodiment shown, and in particular can be displaced along the angle bisector  19 ,  20 . 
     As seen best from FIG. 3, the first pivot axis  5  is disposed perpendicular to the second pivot axis  7  and coincides with the longitudinal axis of the housing  1 . The rotationally fixed housing part  2  is embodied as elongated and slender, so that it fits through narrow tank openings. Through the infeed opening  3 , cleaning fluid flows under pressure into the interior of the housing  1 . A turbine  21  with a stator  22  and a rotor  23  is disposed in the housing part  2 . The rotor  23  is seated on a rotor shaft  24 , with which a sun wheel  25  of a planetary gear  26  is also connected in a manner fixed against relative rotation. 
     The cleaning fluid flows through blades of the stator  22  and the rotor  23  and drives the rotor. The rotor  23  thus turns the sun wheel  25 , which drives first encompassing gear wheels  27 , which in turn are connected to second encompassing gear wheels  28  in a manner fixed against relative rotation. The second gear wheels  28  revolve on a set of internal teeth  31  of the rotationally fixed housing part  2 . The two gear wheels  27 ,  28  have the same number of teeth. One set of internal teeth  29  has a number of teeth that differs by one from the other set of internal teeth  31 , so that after one revolution of the two gear wheels  27 ,  28 , the rotary part  30  and the nozzle holder  4  have rotated by a small angle relative to the rotationally fixed housing part  2 , the angle corresponding to the difference in the numbers of teeth. 
     The rotationally fixed housing part  2 , in its lower region, has a conical set of teeth  32 , which meshes with a cone wheel  33  disposed on the second pivot axis  7 . The cone wheel  33  is connected in a manner fixed against relative rotation to the nozzle assembly  6  that is supported rotatably about the second pivot axis  7 . When the turbine drive now necessarily rotates the nozzle holder  4  about the first pivot axis  5 , the second pivot axis  7  is pivoted, and the cone wheel  3  rolls along the conical teeth  32  of the rotationally fixed housing part  2 . In the process, the cone wheel  33  rotates the nozzle assembly  6  about the second pivot axis  7 . Both rotary motions take place uniformly. 
     The conical set of teeth  32  forty-five teeth, while the cone wheel  33  has only forty-three teeth. This means that the spray pattern created by the nozzles  8 ,  9 ,  10 ,  11  does not repeat until after forty-five revolutions of the nozzle assembly  6  and after forty-three revolutions of the nozzle holder  4 . The mechanical coupling with the fixedly specified ratio of 45:43 between the two rotary motions, together with the acute angle  12  of 40°, produces an optimal adaptation. 
     Downstream of the turbine  21 , the cleaning fluid also flows through the planetary gear  26  and then reaches the inside of the nozzle holder, and from there it is pressed into the nozzle assembly  6  and finally emerges from the nozzles  8 ,  9 ,  10 ,  11  and is sprayed at the inside surface of the tank. Because of the uniform double rotary motion about the two pivot axes  5 ,  7 , a spray pattern is created that uniformly covers the inside surface of the tank. 
     One such spray pattern is shown in FIG.  5 . The paths taken by the fluid stream are distributed substantially uniformly over the inside surface of the tank. A direct comparison between the spray patterns of a four-nozzle machine and a two-nozzle machine is shown in FIG.  6 . As can easily be seen, the spacing between adjacent paths and the mesh width in a two-nozzle machine are twice as large as in a four-nozzle machine. 
     As can be seen from FIG. 3, the drive shaft  36  of the nozzle assembly  6  is provided with a pin  34  protruding radially past the outside diameter of the nozzle assembly; the pin is pressed into a bore intended for it in the drive shaft  36 . The pin  34  projects radially outward and engages a recess  35  in the hub region of the cone wheel  33  that is rotatably supported on the drive shaft  36 . The recess  36  extends in the direction of rotation over an angular range of 180°, so that the cone wheel  33  can be rotated relative to the drive shaft  36  by up to 180° within the angular play, before the pin  34  strikes one of the boundaries of the recess  35  in the direction of rotation and the drive shaft  36  is driven by the cone wheel  33 . 
     This provision assures free rotatability of the nozzle assembly  6 , connected to the drive shaft  36  in a manner fixed against relative rotation, within the angular play while the cone wheel  33  is stationary, so that an alignment of the two V-formations  13 ,  14  longitudinally of the housing is possible even when the drive mechanism is at a standstill. 
     In the modified embodiment of the angular play shown in FIG. 4, a platelike baffle  37  that covers the backside of the nozzle holder  4 , is connected to the drive shaft  36  in a manner fixed against relative rotation, and rotates together with this drive shaft, is equipped in its hub region with an axially inward-projection protrusion  38 , which extends over an angular range of 90° in the direction of rotation. The cone wheel  33  rotatably supported on the drive shaft  36  is likewise equipped in its help region with an axial protrusion  39 , which projects in the axial direction outward, counter to the first protrusion  38 , in the same axial region as the first protrusion and which likewise extends in the direction of rotation over an angular range of 90°. 
     Together, the two protrusions  38 ,  39  cover an angular range of 180°, so that the relative rotation between the platelike baffle  37  and the cone wheel  33  is limited by the protrusions  38 ,  39 , striking one another in the direction of rotation, to the remaining angular range, which again is 180°. In this arrangement, the cone wheel  33  can accordingly be rotated relative to the baffle  37  by up to 180° within the angular play, before the protrusion  39  of the cone wheel  33  strikes the protrusion  38  of the baffle  37  in the direction of rotation, and thus before the drive shaft  36  is driven by the cone wheel  33  via the baffle  37 . 
     For self-cleaning of the tank-cleaning device, a special spray nozzle  40  is provided, which is disposed in the upper region of the rotationally fixed housing part  2  and whose spray direction is oriented downward in the direction of the nozzle assembly  6 . Still further spray nozzles can also be provided for the self-cleaning.