Abstract:
The invention relates to a regulating system for a gas burner. Regulating systems for gas burners are used for guiding a gas flow and a combustion air flow to the burner. The gas flow can be regulated depending on combustion air pressure. Pressure is measured in known regulating devices with the aid of a membrane, that is pneumatically. The pneumatic pressure measurement limits the scope of application of known regulating devices. In the invention regulating device, a sensor ( 16 ) is arranged between a first line ( 10 ) guiding a gas flow and a second line ( 12 ) guiding the combustion air flow, an electric or electronic signal ( 19 ) being generated by the sensor that is used to regulate the gas valve ( 11 ).

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a regulating device for gas burners. Regulating devices for gas burners serve to provide a gas-air mixture, which supplies a gas stream and a combustion air stream to a burner. According to various embodiments described herein, the gas stream is capable of being set as a function of the combustion air pressure by means of a gas valve. 
     Regulating devices for gas burners of the above type are well known from the prior art. In one regulating device, the pressure is determined with the aid of a diaphragm, or pneumatically. See EP 0 390 964 A1. The gas stream is regulated by means of the gas valve as a function of this pressure measurement. However, the one disadvantage with this pneumatic method is that it restricts the scope of use of known regulating devices. In such devices the hysteresis properties of the diaphragm and the forces acting between the diaphragm and the gas valve restrict the working range and therefore the scope of use. Furthermore, the interaction between the low actuating forces and the operating tolerances of the diaphragm as a result of disturbing influences, such as temperature fluctuations or the like, cause a restriction in the scope of use of known regulating devices. 
     There are other regulating devices for gas burners found in the prior are with similar disadvantages. See DE 24 27 819 A1 and DE 43 17 981 A1. 
     SUMMARY OF INVENTION 
     The present invention attempts to provide a regulating device for gas burners, which avoids the disadvantages of known devices, thus providing a greater scope of use. Various embodiments described herein solve the scope of use problem by means of a regulating device for gas burners. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a first embodiment of a regulating device for a gas burner system, and 
     FIG. 2 is a second embodiment of a regulating device for a gas burner system. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention relates to regulating devices for gas burners. A gas/air mixture is to be supplied to a burner(not illustrated). In FIG. 1, a first line  10  supplies a gas stream to a gas burner. The gas stream in the first line  10  flows from a valve  11  to a gas nozzle  15 . 
     A second line  12  supplies a combustion air stream to the gas burner. The combustion air in the second line  12  flows from a blower  13 . The rotational speed of the blower  13  determines the combustion air pressure, and therefore the combustion air stream. The second line  12  contains a throttle point  14  upstream of the gas nozzle  15 . The gas stream in the first line  10  exits from the nozzle  15  into the second line  12 . Therefore, a gas/air mixture exists downstream of the gas nozzle  15  in the direction of the combustion air stream. 
     The embodiment illustrated by FIG. 1 provides a combined 1:1 gas/air mixture regulation. Thus, if the combustion air pressure increases 1 millibar (mbar), the gas pressure will likewise increase by 1 mbar. A sensor  16  located between the first line  10  and the second line  12  provides the combined 1:1 gas/air mixture regulation. The sensor  16  functions as a differential pressure sensor, of the flowmeter or anemometer type. 
     The sensor  16  is connected to the first line  10  by means of a first measuring point  17 . The sensor  16  is connected to the second line  12  by means of a second measuring point  18 . The first measuring point  17  is positioned upstream of the gas nozzle  15 . The second measuring point  18  is positioned upstream of the throttle point  14 . 
     To accomplish the combined 1:1-gas/air regulation presented in the FIG. 1 embodiment, the gas pressure must equal the combustion air pressure. Thus, when the sensor  16  is a flowmeter or anemometer, the flow through the sensor  16  will be zero. If, for example, the combustion air pressure decreases in relation to the gas pressure, the sensor  16  experiences a throughflow from the first line  10  in the direction of the second line  12 . By contrast, if the combustion air pressure increases in relation to the gas pressure, the sensor  16  experiences a throughflow from the second line  12  in the direction of the first line  10 . Accordingly, based on the throughflow quantity and direction, the sensor  16  can determine the pressure ratios between the combustion air pressure and the gas pressure. The sensor  16  generates, as a function of these pressure ratios, an electric or electronic signal  19  that adjusts the gas valve  11 . According to FIG. 1, the signal  19  is supplied to a control or regulating unit  20  which generates a regulating signal  21  for an actuating drive  22  of the gas valve  11 . 
     Consequently, the regulating device of FIG. 1, regulates the gas stream using the gas valve  11  to achieve combined 1:1-gas/air regulation. When the sensor  16  detects a pressure differential of zero between the combustion air pressure and gas pressure, the signal  19  corresponds to a pressure difference of zero and the gas valve  11  operates unchanged. When the sensor  16  detects a combustion air pressure higher than the gas pressure, the signal  19  will activate the gas valve  11  so that the gas stream is increased. This is accomplished by the regulating unit  20  generating a regulating signal  21  for the actuating drive  22  of the gas valve  11 , so that the signal  19  corresponds to a pressure difference of zero. By contrast, when the sensor  16  detects a combustion air pressure lower than the gas pressure, the signal  19  activates the gas valve  11  so that the gas stream is decreased. 
     The gas valve  11  may be designed in a variety of ways. For example, the actuating drive  22  of the gas valve  11  is controlled or regulated so the gas valve  11  switches between the on/off or open/shut states. If the combustion air pressure is higher than the gas pressure, a regulating signal  21  is generated, causing either the actuating drive  22  to open or the gas valve  11  to activate. Likewise, if the combustion air pressure is lower than the gas pressure, the actuating drive  22  will close or deactivate the gas valve  11  based on the regulating signal  21 . A resulting oscillating signal provides information on the proper operation of the regulating system, thus it and can function as a safety signal. With the oscillating sensor signal present, a safety valve (not illustrated) preceding the gas valve  11  can be activated or opened. 
     Alternatively, it is also possible to activate the gas valve  11  to assume any desired opening positions between the on/off or open/shut states. The regulating device of FIG. 1 can be used for air quantity measurement when the gas valve  11  is closed. This is because the sensor  16  has the second measuring point  18  on the second line  12 , upstream of the throttle point  14  in the flow direction of the combustion air. Furthermore, the sensor  16  has the first measuring point  16  on the first line  10  downstream of the throttle point  14  and the gas valve  11  is closed. If the gas valve  11  is closed, the pressure difference across the throttle point  14  can be determined by the sensor  16 , and an air quantity can be measured. 
     The air quantity measurement can be used to set the parameter range of the blower  13  as a function of a configuration of the combustion air supply and smoke gas discharge. The air quantity measurement also can be used to monitor and set a minimum combustion air supply, which is required to reliably start the gas burner. 
     FIG. 2 illustrates another embodiment of a regulating device for a gas burner system that provides combined 1:N gas/air regulation. This is accomplished by using a different transmission ratio in the FIG. 2 embodiment than in the FIG. 1 embodiment. In FIG. 2, a coupling line  23  is positioned between a first line  10  supplying the gas stream and a second line  12  supplying the combustion air stream. In the coupling line  23  there is a first contraction  24  and a second contraction  25 . The first contraction  24  and the second contraction  25  are throttle points. 
     No specific position of the first contraction  24  and the second contraction  25  within the coupling line  23  in relation to the first line  10  and the second line  12  is required. However, the flow resistance of the first line  10  and the second line  12  must be noticeably lower than the flow resistance of the first contraction  24  and the second contraction  25 . 
     In FIG. 2, the coupling line  23  is connected to the second line  12  downstream of the throttle point  14  in the direction of flow of the combustion air. The coupling line  23  is connected to the first line  10  upstream of the gas nozzle  15  in the direction of flow of the gas. 
     In the FIG. 2 embodiment, like in the FIG. 1 embodiment, a sensor  16  is positioned between the first line  10  and the second line  12 . However, in FIG. 2, a first measuring point  17  is positioned in the coupling line  23  between the first contraction  24  and the second contraction  25 . A second measuring point  18  is positioned in the second line  12  upstream of the throttle point  14 . 
     In FIG. 2, a regulating unit  20  generates a regulating signal  21  for an actuating drive  22  of the gas valve  11 , so that a signal  19  from the sensor  16  corresponds to a pressure difference of zero. However, because of the arrangement of the coupling line  23  with the first contraction  24  and the second contraction  25 , combined 1:N-gas/air regulation can be implemented. Thus, an increase in the combustion air pressure of 1 mbar will increase the gas pressure by N mbar. 
     Consequently, in FIG. 2, the gas pressure is intensified in relation to the combustion air pressure. The degree of intensification is determined by the first contraction  24  and the second contraction  25 . 
     Furthermore, either the first contraction  24  or the second contraction  25  may be designed to be variable or modifiable. In that case, it is possible, by modifying or adjusting either the first contraction  24  or the second contraction  25 , to vary the transmission ratio between the combustion air stream and the gas stream, or the intensification. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 List of reference symbols 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 10 
                 First Line 
               
               
                   
                 11 
                 Gas valve 
               
               
                   
                 12 
                 Second Line 
               
               
                   
                 13 
                 Blower 
               
               
                   
                 14 
                 Throttle point 
               
               
                   
                 15 
                 Gas nozzle 
               
               
                   
                 16 
                 Sensor 
               
               
                   
                 17 
                 First Measuring point 
               
               
                   
                 18 
                 Second Measuring point 
               
               
                   
                 19 
                 Signal 
               
               
                   
                 20 
                 Regulating unit 
               
               
                   
                 21 
                 Regulating signal 
               
               
                   
                 22 
                 Actuating drive 
               
               
                   
                 23 
                 Coupling line 
               
               
                   
                 24 
                 First Contraction 
               
               
                   
                 25 
                 Second Contraction