Patent Publication Number: US-2013230381-A1

Title: Device For Monitoring A Pump

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of PCT International Application No. PCT/EP2011/066396, filed Sep. 21, 2011, which claims priority under 35 U.S.C. §119 from German Patent Application No. 10 2010 049 138.1, filed Oct. 22, 2010, the entire disclosures of which are herein expressly incorporated by reference. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The invention relates to a device and a method for monitoring rotating components in centrifugal pumps or systems which comprise centrifugal pumps. 
     Centrifugal pumps are used in a multiplicity of systems where they are subjected to very rough conditions from time to time. The state of a centrifugal pump, in particular of the impeller wheel, must therefore be monitored precisely as a function of the application in order to avoid damage to the centrifugal pump or to the entire system. 
     DE 40 055 03 A1 presents a device for monitoring an impeller wheel by means of a light transmitter and an optical probe. This form of monitoring requires stationary centering of the light transmitter and sensor on the front edges of the vanes. However, this monitoring method is suitable only for a centrifugal pump which delivers a visually transparent medium. 
     DE 10 2008 019 472 A1 discloses a vacuum pump with a pump stator and a pump rotor, wherein the pump rotor contains a transponder. In addition, sensors, a microcontroller and a memory which are connected to the transponder are arranged in the rotor. A reader which is arranged in the stator reads the sensor data of the rotor from the transponder. This type of monitoring makes very stringent demands of the electromagnetic compatibility of the vacuum pump. 
     The object of the invention is to provide a device for monitoring rotating components in centrifugal pumps or systems which comprise centrifugal pumps, which device can be used for any liquid delivery media or delivery media which are laden with solids, and is independent of electromagnetic peripheral conditions. 
     The solution provides a device for monitoring rotating components in centrifugal pumps or systems which comprise centrifugal pumps, wherein the transmission of signals takes place acoustically by means of sound waves. This permits simple and reliable transmission of signals of a monitored rotating component. 
     In one refinement of the invention, liquid and solid sound-conducting media are provided on the transmission link between a first unit, the transmitting unit, and a second unit, the receiver unit. It is advantageous here that the sound can be conducted along a path and the properties of the path can be clearly determined. The phase transitions of the sound between solid and liquid media can be taken into account in the transmission. Corresponding encoding of the signal takes into account losses at the phase transitions. 
     A further advantage is obtained if the first unit has a setpoint value memory in which comparison values for the measured sensor signals are stored. Threshold values which are compared with the measured values can be stored in this setpoint value memory. If a threshold value is reached, a corresponding signal is transmitted to the receiver unit. 
     Degradation of the transmitted signal is prevented by selecting a different frequency for the transmission of information from frequencies of system noise. The term system noise is to be understood as meaning all acoustic emissions of the centrifugal pump and of the components connected thereto. In particular, the combination of different components gives rise to natural frequencies of the system which depend specifically on the individual configuration of the system. As a result of this measure, incorrect interpretations during the analysis of the received signals are prevented. In the case of selective adaptation of the signal, the transmission becomes insensitive with respect to interference as a result of the abovementioned system noise. 
     In order to be able to differentiate ambient noise, that is to say acoustic influences on the centrifugal pump or the system, which is input from the outside from the acoustically transmitted signals, in the second unit a soundwave sensor for determining ambient noise is provided. By means of a suitable filter it is possible to separate the ambient noise from the transmitted signal, as a result of which the signal information is improved. The use of a transmitting device, which is permanently connected to the centrifugal pump impeller wheel, occurs frequently in a very rough environment for electronic components. It is therefore advantageous if the first unit is integrated into a component, in particular if it is cast into the component. The surface of the component therefore at the same time protects the transmitting device. Owing to the acoustic transmission it is possible to integrate the first unit into a metallic component since the acoustic transmission of signals functions outstandingly in metals. Likewise it is possible to integrate the second unit, which comprises the receiver, into a metallic housing or to fit it onto the housing from the outside. 
     The first unit is equipped with an energy supply, this being a battery in the simplest case. Generators can also be provided which acquire electrical energy from the movement of the component, from vibrations or from temperature gradients. The autonomous supply of the first unit with energy is significant, in particular, if the latter is embedded in an encapsulated fashion into the component. In this case, the energy supply has to be ensured for the service life of the component. 
     In one refinement of the invention, the sensor of the first unit is designed to sense component properties of the centrifugal pump or of the system, for example machine temperature, mechanical pressure or stress or component fracture. As a result, selective monitoring of individual components is possible. Particularly component fractures can be detected easily by corresponding fracture sensors which are embodied as wires which run through the component, since an interruption in the wire in the case of a component fracture can be detected through a simple short-circuit of the wire. Furthermore, operating parameters can be sensed by means of a sensor. In the case of the centrifugal pump these are, for example, the rotational speed, power demand or period of use. This permits further monitoring of the components whose state can be heavily dependent on these parameters. 
     In a further refinement it is possible for the sensor to sense properties of the delivery medium. In this context, it is possible, for example, to detect the viscosity, the temperature or the concentration of the medium, which are then evaluated by the microprocessor. The analysis results thereof are transmitted to the outside. 
     Furthermore, a method is to be described for monitoring components having a device as mentioned above, in which an interrogation of the at least one sensor takes place at cyclically recurring intervals. The measured sensor data is compared with setpoint values from the setpoint value memory and when a threshold value is exceeded a signal is transmitted to the receiving unit. Alternatively it is possible to transmit a signal continuously, as a result of which the functionality of the transmitting device can be detected. In the event of a threshold value being exceeded, a signal is no longer transmitted, which indicates a fault which requires checking of the centrifugal pump or of the system. 
     The receiving unit continuously receives noise and selectively filters for possible transmission noise, specifically specifiable frequencies and pulse shapes. If a signal is detected, it is evaluated and either displayed on a display and/or passed on to a superordinate system controller. 
     In a further refinement of the method, during the evaluation of signals information is used which takes into account the ambient noise of the centrifugal pump or system. As a result errors can be reduced. 
     The invention also comprises an impeller wheel of a centrifugal pump which is equipped with the device for monitoring components. This simple and cost-effective device permits contactless monitoring of the impeller wheel, wherein during the contactless or wireless transmission of signals neither properties of the delivery medium nor electromagnetic influences from the surroundings of the centrifugal pump have to be taken into account. 
     For the integration of the device for monitoring components into an impeller wheel it is particularly suitable if the impeller wheel is manufactured from a polymer material, in particular from polymer concrete or mineral casting. These materials are cast cold, with the result that particular protection of the cast-in first unit is not necessary. 
     Further embodiments arise from the combination of the previously presented embodiments and are therefore not explained further here. 
     An exemplary embodiment of the invention is illustrated in the drawing and will be described in more detail below. 
     Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a device for monitoring rotating components in centrifugal pumps or systems which comprise centrifugal pumps. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a device for monitoring rotating components in centrifugal pumps or systems which comprise centrifugal pumps, composed of a first unit  1 , which is permanently connected to the component to be monitored. In addition to an arrangement in the direct vicinity of the component there is the possibility of integrating the first unit directly into the component. This is suitable, for example, if the component is composed of a cast material which can be cast at low temperatures, for example a polymer material, in particular polymer concrete or mineral casting. For this purpose, the ready-configured, autonomous first unit which is configured without cables is cast, for example, into a centrifugal pump impeller wheel. The component itself is not depicted for the sake of simplified illustration. 
     The first unit  1  comprises a sensor  2  for sensing component properties, which sensor  2  is connected to the first unit  1  at a sensor connection  3 . It is also possible to connect a plurality of sensors  2  to the first unit  1 . Possible sensors  2  are, for example, temperature, pressure and/or substance sensors or others. A fracture sensor, which is composed of at least one wire which runs through regions of the component at risk of fracture, is indicated in the figure. If a rupture forms on the component at a location through which the wire runs, the wire will tear as the rupture progresses and the electrical line will be interrupted along this wire. Ruptures in the component can be easily detected in this way. When there is a plurality of wires connected in parallel, progression of the formation of ruptures can also be observed. 
     A microprocessor  4  for analyzing sensor signals directly evaluates the data picked up by the sensor  2  and passes on the analysis result to a transmitting unit  5  for transmission to a receiver which is spatially separate from the monitored component. The frequency of the sensor interrogation depends on the probability of an expected event. Said frequency significantly influences the energy requirement. A low testing frequency gives rise to long battery service lives and is improved further if the system is placed in an energy saving mode or switched off in the intervals between two interrogations. 
     The inventive monitoring of components by means of the acoustic transmission of data constitutes the variant which is the safest and most cost-effective within the design used. The signal  8  can be embodied as an acoustic message telegram which can contain various frequencies, pulse sequences or combinations thereof. By repeating the same signal it is possible to avoid incorrect transmissions. The embodiment of the sound generator, which forms the transmitting unit  5  in this embodiment, depends heavily on the information to be transmitted, the frequencies used and the surrounding delivery medium, since the signal  8  must pass through the latter. It is to be borne in mind here that in the case of an embedded first unit the signal must first exit the component, wherein a transition between the solid component and the liquid delivery medium or delivery medium which is laden with solids takes place. A further transition of the signal takes place if the second unit is also integrated into a solid component, for example into a housing, or if the second unit is mounted on the outside of a housing, within the acoustic range. Furthermore, a source for supplying energy  6  is accommodated on the first unit  1 . A battery and a device which can acquire energy from the movement of the rotating impeller wheel or from temperature distributions in the impeller wheel are suitable for this. 
       FIG. 1  also shows a second unit  9  which is equipped with a receiver unit  10 . The latter is mounted in or on the pump housing during use in a centrifugal pump. Depending on the loading by the delivery medium, the receiver unit is to be provided with protection. As in the first unit  1 , it can be appropriate to cast the second unit  9  directly into the pump housing. The receiver  10  is tuned to the transmitter  5  with respect to its frequency range which can be captured. The signals which are captured are fed to an evaluation unit  11 . In the exemplary embodiment shown, the evaluation result can be shown directly on the pump, for which reason a corresponding display means  12  is provided. The display can take place acoustically or visually. Alternatively, there is the possibility of passing on the evaluation result to a superordinate system controller for which the connection  13  is provided. 
     LIST OF REFERENCE NUMERALS 
       1  first unit 
       2  sensor 
       3  sensor connection 
       4  microprocessor 
       5  transmitting unit 
       6  energy supply 
       7  transmission link 
       8  signal 
       9  second unit 
       10  receiver 
       11  evaluation unit 
       12  display 
       13  connection 
     The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.