Abstract:
A water pump for bodies of water such as ponds, aquariums, or fountains containing suspended particles has a housing with a pump housing part provided with an intake opening and an exit opening, in which housing part an impeller with a shaft is rotatably supported, and a motor housing part in which an electric motor is received. As an improvement, an electronically commutated motor is used and the pump has a power input as well as power and control electronics for the motor having an operating state detection device with speed detection, processor and data storage device. The processor can control an interrupt switch between the power input and the motor. In the data storage device certain characteristic lines in regard to normal operating states can be stored.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a water pump for bodies of water that contain principally not only pollution-free water but also suspended particles, mud, leaves and pieces of algae or similar materials. Such bodies of water are ponds, aquariums or fountains, for example. 
         [0002]    Pumps of the aforementioned kind as they are known in practice have usually a thermoswitch as a safety device. This switch switches off the pump when overheating occurs, for example, as a result of an integrated or downstream filter being clogged by suspended particles or as a result of clogging of a conduit in the feed or outlet lines. Also, when the pump is operated without water being actually conveyed, the pump will overheat so that after a certain amount of time the overheating protection will intervene. 
         [0003]    There are also pumps that are provided alternatively or additionally with a switch-off mechanism that immediately responds when the pump conveys no water. This state is determined in such pumps that operate with load-independent constant speed in such a way that the load on the pump is measured. When the load is extremely low, this means that the pump is running without water. The pump is switched off immediately and, up to this point, has often turned only one fourth of a revolution. When upon start-up the pump is positioned, for example, in a pump sump that is only filled minimally, it is not possible to start the pump permanently because of the early power-off since the pump is not turning long enough, despite taking in air, in order to suck in the required water quantity into the pump sump for the pump to operate properly. Also, it is not possible to test the function of the pump without water because switching off is taking place so quickly that it is not possible to detect whether the motor turns at all. 
       SUMMARY OF THE INVENTION 
       [0004]    It is therefore an object of the invention to provide a pump that avoids the aforementioned problems. 
         [0005]    This object is solved by a water pump wherein the motor is an electronically commutated motor and the pump has a power input as well as power and control electronics for the motor comprising an operating state detection device with speed detection, processor and data storage device. 
         [0006]    The combined use of an electronically commutated motor (EC motor) as well as the provision of power and control electronics with an operating state detection device by means of speed sensing, a processor, and a data storage device, the speed of the pump can be detected, evaluated in the processor and can be utilized by means of the power and control electronics for changing the pump function. An—only imprecise—detection of the load on the pump is no longer required, and an EC motor with load-dependent and accordingly adjustable speed can be used. 
         [0007]    The control electronics can thus lower as needed the speed of the motor such that there is no risk of damaging it. Preferably, the pump has also an interrupt switch between the power input and the motor that, when certain defined operating states occur, interrupts the power input so that the motor is stopped completely. Of course, the pump can have additionally a conventional overheat protection that switches off the pump, for example, by means of a thermocouple and interrupt contact, when the pump is overheating for whatever reason. 
         [0008]    The speed detection required for operating state detection can have a speed sensor that is designed for recognizing the rotor position and the rotary frequency of the motor. This sensor can be, for example, a Hall sensor. It is also possible, and realizable without additional material expenditure by means of the intelligence inherent in the pump, to configure the speed detection without a sensor. In this connection, at any point in time at the coil or coils momentarily not supplied with current and not switched at the moment, the current flow induced by the magnet rotor is measured and, based thereon, the rotor position is determined. In this connection, the speed at which the coils that generate an induced current flow change provides the rotary frequency. Both pieces of information are evaluated by means of the processor and can be utilized for control. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    Further advantages and details result from the dependent claims and the embodiments of the invention illustrated in the drawings which will be explained in the following. It is shown in: 
           [0010]      FIG. 1  schematically a pump according to the invention; 
           [0011]      FIG. 2  a diagram with pump characteristic lines and operating states; and 
           [0012]      FIG. 3  a diagram with speed characteristic lines of the pump. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0013]    The water pump illustrated in  FIG. 1  has a housing  1  that is subdivided into a pump housing part  2  and a motor housing part  3 . The pump housing part  2  has an intake opening  4  functioning as a water intake and an exit opening  5  serving as a water outlet. In the pump housing part  2  an impeller  8  is arranged on a rotatable shaft  9 . The shaft  9  extends from the pump housing part  2  into the motor housing part  3  and into an EC motor arranged therein. The EC motor has a rotor  14  fixedly connected to the shaft  9  and a stator  12  surrounding the rotor. Preferably, the rotor  14  is of a two-pole configuration and the stator  12  is of a six-pole configuration (or a two-pole configuration with protective extra-low voltage). The shaft  9  is supported in an end shield  10  that shields the motor mechanically relative to the pump housing part  2  and the impeller  8 . 
         [0014]    In the pump housing  1  control and power electronics  16  are provided which preferably are arranged also in the motor housing part  3  and thus at a spacing from the water-conveying parts. Included is also a schematically indicated microprocessor  17  that can actuate an interrupt switch  21  by means of a control line schematically indicated by arrow  19 . In this way, the electric supply between the electric power input  26  of the pump, that is connected to a electric cable  36 , and the power electronics  16  and thus the motor can be interrupted. In  FIG. 1 , the interrupt switch  21  is illustrated in the activated position, i.e., current flow is interrupted and the motor is switched off. The illustration of the interrupt switch  21  is only schematic. Of course, not only a mechanical switch but also in particular electronic switches can be utilized. 
         [0015]    The entire electronic device including power electronics  16 , microprocessor  17 , and interrupt switch  21  can be potted so as to be watertight for safety reasons. This holds true also for the stator  12  of the motor. Inasmuch as stator  12  and rotor  14  are separated by a so-called split cage, preferably the entire free motor housing part can be potted to be watertight. 
         [0016]    The pump according to the invention is utilizable in a plurality of ways when in the date storage device information in regard to a normal operating state of the pump is stored. This can be in particular the conventional pump characteristic lines and/or rotary speed characteristic lines. For an optimal control a software is to be provided in the electronics which software performs a nominal/actual value comparison between the stored normal operating state data and the detected actual operating state of the pump detected by the operating state detection device. Upon surpassing a preset difference between these two values, which preset difference is also stored within the data storage device, a change of the operating state of the pump is to be initiated by means of the control device. This change can be, for example, lowering of the speed of the pump or switching off of the pump by activation of the interrupt switch  21 . 
         [0017]    As a result of the speed detection, the pump cannot only comprise control electronics but also governing electronics without significant further material expenditure which governing electronics ensure by a closed-loop control circuit that the target speed of the pump is indeed achieved and maintained. In this connection, the speed is continuously detected, compensated, and possibly adjusted. This is done, for example, in that the permissible and preset difference for the nominal/actual value comparison between normal operating state and actual operating state is set to be very low. 
         [0018]    The application possibilities and the function of the pump according to the invention can be explained particularly well with the aid of the diagrams of  FIGS. 2 and 3 . 
         [0019]      FIG. 2  shows the water flow rate in liters/minute plotted against the pressure or the height in meters that must be overcome by the water with the aid of the pump. The light-colored line  61  is the characteristic line  61  (state  1 ) provided by the manufacturer for the height plotted against flowrate on which characteristic line the pump operates in the normal operating state. However, the pump is also able or capable of providing higher power up to a maximum characteristic line  62  (state  2 ). Additionally,  FIG. 2  illustrates two device characteristic lines  63 ,  64 . The lower device characteristic line  63  represents the proper use of the pump in a normal device in which the pump is usually utilized and for optimal free conduits and filters, i.e., for a device that as a whole is clean. The pump then operates generally at the operating state point A. 
         [0020]    The upper steeper device characteristic line  64 , on the other hand, shows possible operating points of the total device when filters are clogged, the device as a whole is soiled or higher pressures must be overcome for other reasons. In this case or, for example, in the case of a clogged filter, the operating state of the pump moves from point A along the normal characteristic line  61  to the operating state point C. In this connection, the pump no longer achieves the desired flow rate Q; the flow rate drops. By means of the software-supported pump control in such a case the operating state of the pump is moved upwardly along the device characteristic line  64  until the initial and desired flow rate is reached. This is the case at the illustrated operating state point A′. The flow rate of the pump can be increased maximally until the maximum characteristic line  62  is reached. 
         [0021]    The pump therefore can automatically adjust the desired operating state and maintain the flow rate Q at a constant rate, for example, in the case of a filter that slowly becomes clogged, over a long period of time without the operator of the pump having to continuously adjust the pump operation himself. 
         [0022]    The control is optimized in that in the data storage device different pump characteristics lines and speed characteristics lines are stored already at the time of delivery of the pump. The pump can therefore automatically react to changes of the device characteristic line and perform a readjustment to the set output. 
         [0023]    In analogy to the determination of the flow rate based on the diagram of  FIG. 2 , the speed of the pump in different operating states can be taken from the diagram of  FIG. 3 . Numeral  61  indicates again the standard characteristic line and  62  indicates the maximum pump characteristic line. 
         [0024]    The described operating state detection technology is utilized also for dry running and blocking protection. In the case of dry running of the pump, i.e., when the pump takes in no water, the pump has no resistance and therefore rotates at very high speed without any flow; this is indicated by operating state point T. The point T is above the maximum characteristic line  62 . This is recognized by the pump by means of the speed detection and the interrupt switch  21  will be activated. However, in order to prevent in the case of a brief period of dry running, for example, if not enough water is present in the pump sump, an immediate power-off of the pump, the software comprises a predetermined program that first causes one or several speed changes of the pump before the pump is switch off. Such a program can lower the engine speed, for example, once or several times, to the operating point P. An example of such a program course is as follows: 
         [0025]    2 seconds operating point T. 2 seconds operating point P 2 seconds operating point T. 2 seconds operating point P, 2 seconds operating point T. power off. 
         [0026]    During the course of this program pass, the pump has the possibility, for example, if the pump sump is not filled sufficiently, to take in the required quantity of water for its operation. In this way, there is a flow rate Q and the operating point moves on the standard characteristic line  61 . When during the program pass it is detected that the standard operating state is reached, the software is to be designed such that the program is stopped because switching off of the pump is no longer required. 
         [0027]    Such a program can advantageously be used also as a self-test of the pump. When at the time of purchase the pump is connected to a power supply without water being present, the pump runs the afore described program and powers off at the end of the program. The buyer can therefore hear that the motor of the pump is intact. 
         [0028]    When the pump is blocked, for example, in the case of a complete clogging, the opposite of a dry run occurs. In the case of blockage, the speed is reduced to zero at the indicated operating point B. This operating point B is significantly below the minimal desired nominal characteristic line  61  so that this state is detected by the electronic device as a blockage and the pump is switch off. 
         [0029]    The pump according to the invention can therefore be used in different operating states without the operator having to perform his own adjustments. As described, an automatic self-test can be provided so that even at the time of purchase the function of the pump can be demonstrated plausibly. 
         [0030]    The specification incorporates by reference the entire disclosure of German priority application 10 2006 041 317.2 having a filing date of Sep. 1, 2006. 
         [0031]    While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.