Blow and suction nozzle for household or industrial suction tools
BACKGROUND OF THE INVENTION 
     The invention relates to nozzles for household or industrial suction tools; such nozzles serve as attachment (accessory) for the cleaning of objects. 
     For the removal of dust by suction, nozzles of various types are used, mostly as attachments to household and industrial suction tools. The combination of suction nozzles with brush inserts is intended to effect, at the same time, the sweeping and sucking of dust particles. Also known is the use of rotating brush parts. Thus the cleaning effect is intended to be intensified. 
     The above mentioned accessories come into direct contact with the objects to be cleaned and cause damage, especially, if the dust particles settle on delicate objects. Additionally, when cleaning rugged objects, not all dust particles are seized. Especially with small and lightweight objects, the danger of entanglement and overturning is to be pointed out. 
     There is known a vacuum cleaner (German Offenlegungsschrift DE-OS No. 22 18 351) which overcomes most of the above mentioned disadvantages by reversing the intake air after the filter and conducting it back to the nozzle as exhaust air. There is, however, a second separate pipe and tube system required, in addition to the usual suction pipe or suction tube. 
     U.S. Pat. No. 3,328,827 describes a vacuum cleaner the suction blower of which is driven by a pneumatic wheel whereby the compressed air is then blown out via nozzles around the suction jet. The normally used electric motor thus is replaced by the pneumatic wheel. 
     In contrast to this, it is an object of this invention to provide a nozzle for household or industrial suction tools which can be used at will for any suction tool. According to a further object, no additional power supply shall be required. Finally, it shall be possible to do the cleaning without coming into contact with and therefore without mechanical damage to the object to be cleaned. 
     SUMMARY OF THE INVENTION 
     To solve these objects the invention is characterized in that a first turbine wheel is located within the nozzle and is driven by the intake air flow and operates a second turbine wheel that generates a blown air flow directed to the object to be cleaned by means of at least one blow pipe. 
     According to the invention, the blow and suction nozzle utilizes the driving force of the intake air of vacuum cleaners or other suction tools in order to drive the turbine wheel positioned in the intake air flow. This moves a second turbine wheel in the compressed air part of the device which in turn generates an exhaust air flow via a blow pipe. Without additional power supply, thus a blow pressure together with the suction effect is achieved by means of a counterflow process. The raised dust particles are taken into the suction tool together with the suction flow existing anyway. By means of a coaxial arrangement of the turbine wheels, a technically uncomplicated and lightweight construction of the device can be achieved. With permanent lubrication, maintenance is not necessary. 
     In a preferred version of the invention, the nozzle consists of a pressure pipe in which ends coaxially a suction pipe whereby the thus resulting annular surface separates the pressure and suction area, and the blow pipe is connected to the pressure area via connecting tubes ending in an annular surface thereof. The connecting tubes enable an optional design of the blower section adapted to the respective purpose. 
     In an especially preferred version of the invention, a cap is put onto the nozzle in the suction area thereof, said cap being tapered at the mouth of the blow pipe in such a way that an eddy (air whirl) of the intake and exhaust air flows is generated. This controlled turbulence taking place at some distance from the mouth of the blow pipe achieves a noticeable cleaning effect on the objects to be cleaned. The loosened dust particles are seized from the whirling intake air flow without the object being blown at having to serve as a deflecting surface to return the exhaust air flow. Contrary to the known blow or suction nozzles having their highest effect in the immediate vicinity of their entrance ends, the blow and suction nozzle of the invention has its highest effect at a distance of e.g. approximately 5 cm from the mouth. Therefore, when cleaning especially small objects, there is no danger that these are overturned by the exhaust airflow or sucked into the intake airflow. With the cap removed, an especially strong blow pressure can be achieved as the blow pressure now is not influenced by the return flow of the intake air. 
     As a result of the construction as per the invention, the nozzle can be exchanged quickly and simply for other attachments. The working principle on which the invention is based can be used, however, also for other machines or instruments as an integrated part. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the following the invention is described in detail by means of some examples of design as shown in the drawings in which: 
     FIG. 1 is a longitudinal sectional view of a nozzle of the invention with turbine wheels set one behind the other on a common shaft; 
     FIG. 1a is a sectional view along line Ia--Ia of FIG. 1; 
     FIG. 2 is a longitudinal sectional view of a nozzle of the invention with turbine wheels set coaxially at one plane; 
     FIG. 3 is a longitudinal sectional view of a nozzle of the invention with a cap in the suction area of the nozzle; and 
     FIG. 4 shows the nozzle of FIG. 3 without cap. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     According to FIGS. 1 and 1a, a suction pipe 1 consists of two straight-lined sections 3 and 4 connected by a knee 2 of 90°. Section 4 and knee 2 are located in a pressure pipe 5 coaxial with section 4, while section 3 runs sealed through the jacket of pressure pipe 5 to the outside serves for connection to a suction tool, e.g. the suction pipe of a vacuum cleaner. In section 4, a coaxial tube 6 is mounted projecting into pressure pipe 5 through a wall of knee 3. At both ends of tube 6, two turbine wheels 7 and 8 are rotatably mounted one behind the other and which are connected by shaft 9. The wing rims of these turbine wheels 7 and 8 are set in such a way that turbine wheel 7 in the suction pipe is driven by the intake air flow of the suction tool thereby starting to move also turbine wheel 8 in pressure pipe 5 via shaft 9, and the exhaust air flow generated by wheel 8 is directed opposite to the intake air flow, as indicated by arrows S (intake air flow) and arrows B (exhaust air flow). On the free side of turbine wheel 7, suction pipe 1 and pressure pipe 5 are connected by an annular plate 10 being equipped with holes 11 spaced in circumferential direction, to which holes connecting tubes 12 are attached in a conical arrangement. These connecting tubes 12 end in a blow pipe 13 which ends at approximately the same plane as pressure pipe 5 so that an annular space 14 is formed between the blow pipe 13 and the pressure pipe 5, which space is only interrupted by the connecting tubes 12. The outer jacket of suction pipe 1 separates the pressure and suction area. 
     The compressed air generated by turbine wheel 8 at first flows through the area between suction pipe 1 and pressure pipe 5 and from there it arrives in blow pipe 13 through the connecting tubes 12. The emerging exhaust air flow is directed, as indicated by the arrows, to any object, e.g. a plate 15, is then reflected from that and mixed with the intake air, and is finally together with the intake air sucked into suction pipe 1 whereby the intake air flow passes at first the annular space 14, then runs through between the connecting tubes 12, and finally arrives in suction pipe 1 through a central opening of annular plate 10. 
     In the embodiment according to FIG. 2, a suction pipe 16 has a constriction 17 at its front end surrounded by a pressure pipe 18 being distanced from the broadened part of suction pipe 16 by an annular space 19 to let the air in. The rear end of suction pipe 16 serves as connection to a suction tool. To generate the intake or suction, and exhaust or blow air flows (arrows S and B, respectively), a common turbine wheel unit 20 is provided which has an inner turbine wheel 21 rotatably mounted in the constriction 17 and, coaxially therewith, an outer ring-shaped turbine wheel 22 that is only rotatably mounted in the annular space between pressure pipe 18 and constriction 17. The wing rims of the turbine wheels 21,22 are set into opposite directions so that the intake air and the exhaust air flow are opposite to each other. In the area of turbine wheel unit 20 the constriction 17 is divided to accomodate a sliding surface of turbine wheel unit 20 located between the two turbine wheels 21 and 22 for bearing both of them at the same time. A suitable sealing in this area is also provided. Otherwise, the configuration corresponds with FIGS. 1 and 1a. The intake air and the exhaust air again flow, as indicated by the arrows, in opposite directions, i.e. similar to a counterflow. 
     The embodiment of FIGS. 3 and 4 corresponds with the embodiment of FIG. 1 in its rear section, and therefore identical parts are designated by the same reference numbers. Connecting tubes 24 are, however, mounted parallel to the axis of a blow pipe 31. These tubes 24 are set into the holes 11 of annular plate 10 and end in the openings of a circular plate 25 the radius of which is somewhat smaller than the radius of the pressure pipe 5 ending at annular plate 10. According to FIG. 3, a cap 26 can be put onto the nozzle. Cap 26 has an annular section 27 that surrounds the connecting tubes 24 and is slid with clamp fit onto the annular plate 10. Preferably, cap 26 is coaxial with the nozzle. From the location at which plate 25 is provided, cap 26 has for example a cone-like tapering portion 28 ending at the front end of the jet in a cylindrical part 29. Similarly, for example a conical wall section 30 is mounted onto plate 25 and ends in a cylindrical section 31. Thus a conical space is formed between tapering portion 28 and wall section 30 whereas a cylindrical annular space is formed between part 29 and section 31. Part 29 and section 31 end in approximately the same plane. Similar to the other embodiments, the exhaust air is blown out through the connecting pipes 24 and the section 31 being effective as a blow pipe. With the cap 26 put on, however, the exhaust air and the intake air whirl into each other automatically at some distance from the mouth of section 31 (compare the arrows), and then the united air flows are sucked through the cylindrical and conical spaces respectively and between the connecting pipes 24 into suction pipe 1. With the cap 26 removed as shown in FIG. 4, the exhaust air is deflected from an object as shown in FIGS. 1 and 2 and then transported as intake air through the space between the connecting pipes 24 into suction pipe 1. 
     The effect of the jet can be influenced by the following measures: 
     Position of blow pipe mouth with respect to the suction nozzle of the outer cylinder, 
     Modification (reduction) of the suction flow, 
     Modification (reduction) of the exhaust flow, 
     Shape of blow pipe nozzle, and 
     Shape of suction nozzle of pressure pipe or cap. 
     According to further embodiments of the invention, the pressure pipes can also be mounted inside the suction pipes such that the suction pipes are the outside pipes of the nozzle.