Abstract:
Dosing mechanism to feed germicide or disinfectant into a water supplied supply device in order to provide disinfected water for consumers. Said dosing mechanism comprises a disinfectant storage tank ( 12 ), pathway for water flow ( 20 ) leading to at least one junction point ( 30 ), a remote-controlled feeder ( 22 ) enabling germicide to be added, a control device ( 52 ) working together with a flow metro which detects flow volume of water supplied and transmitting it as a signal to the control device ( 52 ) which actuates the feeder ( 22 ) according to a predefinable concentration of germicide in water. The storage tank ( 12 ) is pressurized with compressed air and the feeder is designed as a proportional valve ( 22 ) which can be actuated by the control device.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention concerns a dosing device for introducing germicide or disinfectant into a water-supplied supply device for making aseptic or disinfected water available to users. 
     2. Description of the Related Art 
     It is generally known to disinfect water by addition of certain chemical substances. In these cases it is conventional to add germicides or disinfectants in tablet form or, in larger amounts, as solutions to the water to be disinfected in order to achieve a better mixing of the water to be disinfected. Independent of the type of addition, for the desired germicidal or disinfecting action attention must be given to make sure that a good mixing of the water with the germicide or disinfectant occurs. 
     A common environment of use is in the disinfecting of water needed by patients for dental hygiene in dental practices, for example for rinsing out the mouth. 
     Conventionally, dosing devices are employed for this, with which the water is periodically injected or inoculated. This means that the disinfectant is added at regular periods, since this device largely works on the basis of clocked magnets, which are associated with the pumps and/or valves employed therefor. 
     These types of components allow only large switch intervals, so that the intervals between the individual injections are correspondingly large. This results in substantial fluctuations in the concentration of the disinfectant in the water. 
     A further known device includes a supply container for disinfectant charged with compressed air, which is connected with a receiver via an appropriate pipe or hose conduit. In this delivery path a remote operable inlet valve for the disinfectant is provided, which controls the introduction of the disinfectant into the flow path of the water which goes to the receiver. Upon activation of the receiver this supply valve opens and in inactive times it is closed. 
     A particularly high volume concept of the water is not envisioned in this device. The mixing in of the disinfectant occurs with the help of a periodic magnet valve, of which the opening occurs periodically cyclically, as soon as the dispenser, for example pouring water into a glass for rinsing the mouth, is switched on, that is, as upon activation of the outflow. Here also fluctuations on concentration are unavoidable. 
     Finally there is known from DE 34 03 640 A1 a dosing device, which is the starting point of the present invention. In this device the disinfectant is introduced into the water in a special mixing chamber, which is incorporated in the supply conduit. The pressure conduit of a disinfectant conveying piston pump discharges into this mixing chamber. 
     For the purposes of dosing a control device is provided, which acts upon the piston pump in correspondence to the flow amount or, as the case may be, the flow velocity in the supply conduit, so that the desired amount of disinfectant is conveyed out of the supply container. The control of the piston pump can be achieved either by the rotation count of the drive motor or the transmission relationship of the reduction gear mechanism, in order to appropriately adapt the pressure stroke of the pump. 
     It has been found to be a disadvantage herein that the disinfecting action of the germicide is substantially limited in range to the mixing chamber itself. With longer periods of inactivity, as are conventional in the dental practice for example during two sequential days of the weekend, there exits the danger that the disinfecting action is reduced and impermissibly high contamination values occur. Further there occurs the problem, that in the course of the normal useage dead bacteria and other organic substances adhere as the so-called bio-film in the area of the supply conduit and in the downstream water conveying paths, which is an ideal nutrient supply for further germ growth. It is thus necessary to undertake a complete sterilization (basic- or intensive disinfecting) at regular intervals. 
     To do this the device must be taken out of commission. Thereafter the various hose connections must be released and there follows the connection to a separate pump system, which is specially provided for the complete disinfecting and the treatment with a 100% concentration of disinfectant introduced with the objective of removing the bio-film and sanitizing the water supply elements. Thereafter the conduit system must be rinsed with clean water, in order to avoid a subsequent unacceptably high concentration of disinfectant at the resumption of operation. A cleansing process of this type is time and cost consuming. 
     Further, the construction cost for this type of device is substantial, since besides the mixing chamber to be employed in the supply line, the piston pump in particular inclusive of its controls is relatively complicated. Besides the necessity to influence the rotation and/or the transmission relationship of the drive there must be provided special precautions in the form of over-pressurization valves and return conduits, in order to assure functional safety. 
     Finally, there occurs also in this device the undesirable fluctuations in concentration of germicide in the water, since the piston pump cyclically introduces the germicide corresponding to the stroke volume of the piston pump. 
     Beginning with this state of the art it is the task of the invention to provide a dosing device of the above-described type, which is simple in construction and easy to operate and which insures an addition of germicide corresponding to the requirements. 
     SUMMARY OF THE INVENTION 
     In invention is based upon the idea of completely dispensing with the pump inclusive of its complicated control, and in place of this to provide a simple supply container which can be charged with compressed air, and to achieve the addition of germicide/disinfectant via a proportional valve controlled by a control unit. Besides the simplified construction associated therewith, there results a constant addition of germicide/disinfectant material into the water flowing by. Concentration fluctuations, as had been presumed to be unavoidable in all previous dosing devices, no longer occur here. Herewith there can be achieved a secure and reliable disinfecting with reduced amounts of germicide/disinfectant. 
     The required conveyance pressure, with which the supply container is to be charged, can most economically be found in the environment in which this type of dosing device is to be operated. As an example, there can be mentioned the pressure air connection for the drive means for a drill turbine of a dental unit. 
     Beyond this, the mixing chamber can be completely dispensed with since the disinfectant can preferably be introduced directly into the supply line via the proportional valve. Because of the small space requirement of the proportional valve it is possible to provide the introduction point immediately adjacent the work place, so that contamination hardly ever occurs even in the case of longer periods of nonuse. 
     As proportional valve, preferred is a piezoelectric valve, which can be constructed particularly compactly and besides this is reliably controllable. 
     According to a further preferred embodiment of the invention the proportional valve is controllable through the control device such that the concentration of disinfectant is adjustable variably between 0% and 100%. Therewith it is possible to carry out the intensive sanitation which is required from time to time without any particular or supplemental measures. The proportional valve is so controlled in connection with the supply valve for the water, that the water supply can be completely blocked and subsequently disinfectant can be released. For the subsequent rinsing process it is essentially only necessary that the introduction of disinfectant halted, so that pure water can flow. The switching of these operating conditions occurs by the control device, wherein no further construction components or reconfiguration is necessary. 
     According to a further preferred embodiment a device is provided for determination of the actual value of the concentration downstream of the introduction point, which is connected with the control device for a closed circuit or control feedback loop. Therewith the actual achieved concentration can be continuously monitored and maintained to a constant precise value. 
     Further, a dosing device is preferred which includes a device for self-calibration, in order to counteract indications of age or changes in the response relationship of the proportional valve even after longer periods of use. It is envisioned, that the self-calibration can be allowed to occur automatically at certain, fixed, pre-determined time intervals or also automatically after longer periods of inactivity. 
     According to a further embodiment of the invention the introduction of the germicide is provided in the flow path of the treated water upstream of the flow meter. 
     Herein it is advantageously taken advantage of, that the flow meter improves at least a rotational body, for example an impeller, worm wheel or propeller, which thoroughly mixes the supply or feed water and the introduced germicide and thereby uniformly mixes these with each other. 
     In a useful embodiment of the invention the inlet of the germicide is provided in the flow path of the feed water in the area of the user. 
     According to a further preferred embodiment a recoil or backflow valve is provided between the point of the introduction of the germicide into the flow path of the water and the supply container, which effectively precludes the admission of water into the supply container. Further, a filter device is preferably also provided between the point of the introduction of the germicide into the flow path of the water and the supply container, which precludes the admission of impurities and/or clumps from the supply container, which would adversely impact the mixing and solubility in water. 
     In the case that greater than conventional amounts of germicide are needed, a second conduit with a second feed valve for the introduction of the germicide into the stream or flow of the water can be provided, which operates parallel to the first feed valve, and which brings about a more rapid introduction of the germicide at a second introduction point and is position, for example, down stream of the first introduction point. 
     Further preferred variations are concerned with the concept of an integrated buffer storage for sanitized water. So it can be necessary, in the case of strongly septic water, to increase the dwell time of the germicide to be dosed. For each type of germ a different residence time of the germicide is necessary. A buffer zone or buffer space insures, even in heavy use, the maintenance of the necessary dwell time between dosing and outflow at the instrument end. The buffer zone or buffer storage offers a possibility for this by increasing the dwell time of the germicide treated water. 
     It is preferred when the buffer storage area is constructed of a packet of tubes, which for example is comprised of a plurality of flat tubes positioned adjacent to each other. It is particularly space saving when the bundle of tubes has a rectangular or quadratic cross-section, so that the flow cross-section is optimally utilized. The tube packet is closed at the respective end pieces for the formation of a through-going flow path, wherein the end pieces exhibit apertures or through holes of the type, such that a fluid-tight, respective pair-wise connection of two adjacent tubes results. 
     It is preferred that the buffer storage area is introduced in a receptacle housing, so that a supplemental module is formed, which can be placed either immediately on the housing of the dosing device or alternatively can be positioned downstream of the dosing device. 
     In a preferred embodiment the inventive dosing device is formed as an add-on module, which is integratable into an existing dental hygiene apparatus. 
     The inventive dosing devices are preferably employed with devices for dental hygiene, for example in dental equipment used in the dental practice. In contrast to the known devices of this type, the determination of the amount of germicide or disinfectant to be introduced is based exclusively upon the amount of water flowing through. From this it follows, that the taking into consideration of further factors, for example the environment and the pressure, in which the inventive dosing device is to be employed, is not necessary for the function thereof. The retrofitting of existing dental units which do not have disinfection capability is therewith economically possible. Likewise, the inventive dosing device is suitable for dosing of similar substances, such as for example cleansing substances. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     On the basis of a schematic represented embodiment of the invention, the invention including preferred embodiments and improvements as well as particular advantages thereof will be described in greater detail. There are shown: 
     FIG. 1 schematic diagram for a circuit arrangement of a dosing device according to the invention; 
     FIG. 2 side view of an inventive dosing device; 
     FIG. 3 top view of the dosing device according to FIG. 2; 
     FIG. 4 end view of the inventive dosing device according to FIG. 2; 
     FIG. 5 buffer storage as add-on module; 
     FIG. 6 dosing device with buffer storage. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In FIG. 1 a dosing device  10  is shown with a supply container  12  for fluid disinfectant, wherein the supply container  12  is provided on its upper side with a, here only diagrammatically represented, refill pipe with integrated strainer  14 , through which the filling of the supply container  12  with disinfectant occurs. 
     Further, the supply container  12  includes on its upper side a connection pipe  16  for the pressure line  17 , by means of which the supply container  12  is charged and internally pressurized. 
     Thereby it is ensured that the disinfectant can stably flow out of the supply container  12 . 
     For this purpose an outlet pipe  18  is provided on one side, which in FIG. 1 is the left side, which is connected with a supply line  20 , which leads to a first supply valve  22  constructed as a proportional valve. This first supply valve  22  is constructed as an electrically operable proportional valve to introduce the amount of the disinfectant to be supplied via the first supply line  23  into a water pipeline  24 . 
     The water pipeline  24 , in which likewise an electrically operable valve  26  is provided, leads from a not shown supply network to a junction point  30  for one or more, here likewise shown, users. 
     In the water pipeline  24  of the pipeline segment shown in FIG. 1 there is to be found a first inlet point  28  for a first supply line  23  for disinfectant. 
     Downstream of this inlet point  28  there is provided a flow meter device  32 , which via a signal circuit  33  is connected with acentral control unit  52 , which via line  51  is supplied with electrical energy from a here not shown electrical supply network, and which flow meter measures the amount of water flowing through inclusive of the introduced disinfectant and transmits this to the central control unit  52 . Herein it is to be noted that the amount of disinfectant is in the range of 1 to 2% and thus is of negligible influence on the determination of the flow amount of water. 
     Beyond this it is possible, by appropriate programming, to adapt the recognition signal, for example, by an appropriate compensation equation, to factor out this small addition amount of disinfectant. 
     Further it is possible using circuit technology to close the supply valve  22  formed as a proportional valve for a short period of time for several milliseconds prior to making each measurement value, the behavior of the valve being similar to a condenser, in order to empty this prior to controlling with the new voltage or signal. Thereby a drift of the actual value is precluded. Since the removal of treated water respectively occurs for only a short period of time and the addition of disinfectant occurs during this interval of operation, it is also possible in this way that the potential occurrence of a drift dependent small actual value variation or deviation can likewise be disregarded. 
     Between the flow meter  32  and the junction point  30  for the one or more users there is provided a further introduction point  34  for disinfectant. This introduction point  34  is connected via a second supply line  36 , in which a second, likewise electrically operable, supply valve  38  is provided. 
     The manner of operation of this dosing device  10  is as follows. The supply container  12  is filled via fill pipe  14  with disinfectant. The therein integrated filter serves to prevented the entry of impurities into the dosing device. In order to make possible the filling with disinfectant, the previously discussed pressurized air supply via the feed pipe  16  or, as the case many be, via the thereon connected line  17 , is blocked by operation of an appropriate closure means  40 , valve, or slide and the supply container  12  is without pressure. 
     As soon as the supply container  12  is sufficiently filled with disinfectant, the fill pipe  14  is closed pressure tight. Now the pressure air valve  40  is opened, so that the pressure air from line  17  enters into the supply container  12  via the pressure air feed pipe  16  and charges the therein situated disinfectant with pressure. A pressure regulator  42  provided in the pressure supply line  17  regulates the air pressure, which is between approximately 0.4 to 0.5 Mpa, to approximately, for example, 0.3 MPa and insures thereby for an even pressurization in the supply container  12  as well as therefore, that the supply container  12  experiences no impermissible stresses from a too-high over-pressurization. A likewise provided manometer  44  for control shows the actual pressure. Herein it is to be noted, that for the problem-free operation the pressure value in the supply container  12  must consistently be sufficiently above the pressure of the water. 
     Via the outlet pipe  18  positioned at the end close to the ground the disinfectant proceeds via the supply line  20  first to a therein situated fine filter  46  which retains any fine impurities and/or clumps of the disinfectant, which would detract from the solubility in water. Downstream there follows a back-flow valve  48 , which prevents a reversal of flow into the line  20  and therewith prevents entry of water into the supply container. 
     Behind the back-flow valve  48  there is a branching  50 . From there the first supply line  23  runs to the first supply valve  22  and the second supply line  36  runs to the second supply valve  38 . 
     Depending upon the value of the flow volume determined by the flow meter  32  a signal is transmitted to the central control unit  52 , which processes this signal and therefrom determines the opening, that is the width of the opening, of the first supply valve  22  and controls this via a control line  21 . 
     In the same way water valve  26  is controlled by a control circuit  25 . Likewise the degree of fill of the supply container  12  is transmitted via signal circuit  13  to the central control unit  52 . The central control unit  52  serves both for monitoring and determining all relevant operational parameters as well as for the optimal process control of the individual valves. 
     In the case that a particularly large amount of disinfectant is to be introduced, for example for basic sterilization, then supplemental disinfectant can be introduced into the water supply line  24  through the second supply  36  via the second supply valve  34  connected to the central control unit  52  via control circuit  39 . This can also be combined with a blockage of the water line  24  via valve  26 . 
     The addition or introduction of the disinfectant occurs as previously discussed, upstream of the flow meter, so that a better mixing of the disinfectant with the water to be disinfected is achieved. Beyond this it is possible that in certain cases additives are added to the disinfectant, such as for example for preventing the depositing of calcium and algae, as well as for further reducing the surface tension, to improve the effectiveness of the flow meter and thus insure a problem free operation for the longest possible period of time. 
     For self-calibration the control unit  52  blocks the water valve  26 . Thereby there is produced between the supply container  12  and the junction point  30  the pressure existing in the supply container  12  as pressure gradient, in order to allow the disinfectant to flow with an elevated flow rate through the valve  26  and the flow meter  32  upon opening by a user. 
     The control unit  52  sequentially sends at least three fixed different voltage values to the valve  26 , which opens in response. Via the flow meter  32  the control unit  52  detects the actual flow rate, calculates the deviation from the prescribed characteristic curve (flow rate in dependence from valve voltage) and determines correction values for the adjustment of the characteristic curve. This correction values are stored (EEPROM) and are available until the next calibration process, in order to achieve the actual index values for the intended voltage for the valve  26 . 
     In FIG. 2 a practical constructed device of an inventive dosing device  10  is shown in side view, from which representation it is possible to recognize the very compact and at the same time very useful design. The representation in the further FIGS. 3 and 4 clarify the compact shape of the housing  11 . 
     The inventive device  10  includes a housing  11 , of which the wall is preferably comprised of an anti-static plastic which is easy to take care of and clean, for example polyurethane, and of which the inner side cross-section can be recognized from the indicated dashed lines. The housing  11  is formed step-shaped and possesses a flat area and an elevated area. The elevated area, which is on the right side in FIG. 2, is covered by a pivotable folding lid coupled or hinged on the lower right end side of the housing  11 , which lid is held in the rest position by a screw lock mechanism  55  and which makes possible in a simple manner to have rapid access to the supply container  12  situated inside of the housing  11 , in order, for example, to fill it. 
     In FIG. 2 the supply container  12  is represented with broken lines, since in this view it is covered by the side wall and thus under normal conditions not visible. Likewise represented with broken lines is the filling connection pipe with filter  14  positioned above the supply container  12 . On the right side of the housing  11  an exhaust valve  41  is positioned covered by the folding lid  54 , which exhaust valve is preferably integrated in the air pressure valve  40 . 
     Below this, on the front surface of the flat area of the housing  11 , that is, in the plane of the drawing, there are the control elements for setting the device or, as the case may be, for adjusting the operating perimeters, are provided on a control panel  56  easily accessible and visible. 
     Individually on the control panel  56  are provided the Manometer  44  and the second supply valve  38 , which is shown here as a manually operated magnetic valve, as well as three light indicators  58 , which are preferably constructed as LEDs. Finally, a model identification plate  59  is provided on the panel  56 . 
     On the lower side of the housing  11  there are provided base feet  60 , preferably of rubber, upon which the device is set up substantially sound insulated. Further, mounting screws  62  for securing the housing  11  are provided on the sides of the housing  11 , by means of which a securing or mounting within a larger device is possible. 
     On the side opposite to the folding lid  54 , which in FIG. 4 is shown as a side view, as well as on the side of the housing  11  lying opposite to the control panel  56 , there is respectively one special opening  64 ,  66  provided as so-called hose port, through which the supply lines  17 ,  19  for the pressurized air as well as for water are introduced. In FIGS. 5 and 6 the construction or design of a buffer storage  70  is represented. It is comprised of a flat tube packet  72 , which is formed of multiple, adjacent to each other lying tubes  71  with rectangular cross-section. For forming a through-going flow path  73  end pieces  74  are provided on the end surfaces, which respectively exhibit through-holes  76  of such a design, that fluid tight, pair-wise connections between respectively two adjacent pipes  71  are provided. Seals  77  are provided between the end pieces  74  and the tube packet  70 . 
     The so constructed buffer storage  70  is seated in a receptacle housing  78 , which can be situated immediately adjacent to the housing  53  of the dosing device, as shown in FIG.  6 . Likewise it is also possible, with appropriate other design and construction of the housing  78 , to employ the buffer storage  70  downstream of the dosing device. 
     Reference Number List 
     Dosing device 
     Supply container 
     Signal line (fill condition) 
     Fill junction pipe with strainer 
     Pressurized air connection pipe 
     Pressurized air line 
     Outlet connection pipe 
     Water supply line 
     Supply or introduction line 
     Control line (first supply valve) 
     First supply valve 
     First supply line 
     Water conduit, flow path 
     Control line (water valve) 
     Water valve 
     First introduction point 
     Junction point 
     Flow meter 
     Signal line 
     Second introduction point 
     Second supply line 
     Second supply valve 
     Control line (second supply valve) 
     Pressure air valve 
     Exhaust valve 
     Pressurized air regulator 
     Manometer 
     Fine strainer 
     Back flow valve 
     Branching 
     Electrical supply line 
     Control unit 
     Housing 
     Folding lid 
     Screw lock 
     Panel 
     Light indicators (LED) 
     Model identification plate 
     Base feet 
     Securing screws 
     Hose port 
     Hose port 
     Buffer storage 
     Tube 
     Tube packet 
     Flow path 
     End piece 
     Through-holes 
     Seal 
     Receptacle housing