Abstract:
An ultrasonic wave passes different fuels of different concentrations with different velocities. The present invention provides a detecting and controlling device where, by a non-touching method, a velocity for an ultrasonic wave in a first fuel with a first fuel concentration is measured. The velocity obtained is taken for a comparison with another velocity for the same ultrasonic wave in a fuel with a default fuel concentration so that the first fuel concentration of the fuel can be under controlled.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a detecting and controlling device; more particularly, relates to emitting an intermittent pulse wave by a transducer element to pass through a fuel pool and be reflected back to be received by a comparator for a time-deviation comparison with a base signal representing a standard fuel concentration or a default acoustic velocity, where the time deviation obtained can be turned into a control signal to remain a fuel concentration of the fuel pool with a valve or a pump. 
     DESCRIPTION OF THE RELATED ARTS 
     Following the development of the modern science, the consumption of the natural resources are increasing. To solve the energy problem, a fuel cell with high effectiveness and low pollutant is disclosed as a substitute to the internal combustion engine. In 1957, Willard T. Grubb proclaimed a Proton Exchange Membrane Fuel Cell (PEMFC). But, the PEMFC uses hydrogen as a fuel which is either stored in a gas cylinder with high pressure and so is of high danger; or, it may use the Hydrogen Storage Alloy to provide hydrogen which is too heavy and is inconvenient for supplying. 
     To solve the above problem, a Direct Methanol Fuel Cell (DMFC) using a methanol solution as a fuel is provided with easy supplying and high safety. Although the DMFC comprises a small volume and a steady and long-term power supply, its power-generating efficiency is much lower than that of the PEMFC, which reaches only one-fifth to one-third of that of the PEMFC. In addition, the methanol crossover of the methanol solution directly affects the DMFC&#39;s efficiency. The concentration and the temperature of the methanol solution also directly affect the output efficiency of the electrical energy. It means that, under different temperatures or different concentrations of the methanol solution, deviations of the output current density will happen. Furthermore, the method for sensing the concentration of the methanol solution in the DMFC is based on electrochemistry. After a certain period of time, carbon monoxide will be produced to poison the platinum electrode so that the sensor has to be replaced regularly resulting in cost increase. Moreover, the sensor for electrochemistry comprises a big volume, which is not suitable to the minimization of the DMFC power system&#39;s volume. So, the prior arts do not fulfill users&#39; requests on actual use. 
     SUMMARY OF THE INVENTION 
     Therefore, the main purpose of the present invention is to provide a detecting and controlling device of low cost for the fuel concentration of a fuel cell. 
     To achieve the above purpose, the present invention is a fuel-concentration detecting and controlling device for a fuel cell, comprising a comparative fuel pool, a comparator, a server, a controlling device and a pure fuel pool, where the comparative fuel pool comprises a standard fuel pool and a fuel-mix pool; the controlling device is a controlling valve and/or pump; the standard fuel pool and the fuel-mix pool are each connected to a waveform transforming circuit respectively; a first and a second transducer elements are respectively deposed between places where the standard fuel pool and the fuel-mix pool are connected with the waveform-transforming circuits; a time deviation is obtained by a comparator through a comparison of different arriving times of an ultrasonic wave passing through the standard fuel pool and the fuel-mix pool with different fuel concentrations; a control signal based on the time deviation is sent to drive the controlling device by the server to add a fuel (such as a methanol solution) from the pure fuel pool into the fuel-mix pool for balancing the fuel concentrations of the standard fuel pool and the fuel-mix pool between 3.5% and 4%; the first and the second transducer elements are sensors of ultrasonic element provided with tiny electricity for reducing cost and minimizing the concentration variation of the fuel-mix pool; and, the ultrasonic element is made through a micro-machine production for a volume minimization. Accordingly, a novel fuel-concentration detecting and controlling device for a fuel cell is obtained. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
       The present invention will be better understood from the following detailed descriptions of the preferred embodiments according to the present invention, taken in conjunction with the accompanying drawings, in which 
         FIG. 1  is a view showing a first preferred embodiment according to the present invention; and 
         FIG. 2  is a view showing a second preferred embodiment according to the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following descriptions of the preferred embodiments are provided to understand the features and the structures of the present invention. 
     Please refer to  FIG. 1 , which is a view showing a first preferred embodiment according to the present invention. As shown in the figure, the present invention is a fuel-concentration detecting and controlling device for a fuel cell, comprising a comparative fuel pool  1 , an ultrasonic element  2 , a comparator  3 , a server  4 , a controlling device  5  and a pure fuel pool  6 . Therein, the comparative fuel pool  1  comprises a standard fuel pool  11  and a fuel-mix pool  12  separated by a barrier  15 . The standard fuel pool  11  is filled with a fuel having a standard mixture rate. The barrier  15  is made of a material having high thermal conductivity and no chemical reaction with the fuel for balancing temperatures of the two fuel pools  11 ,  12 . The ultrasonic element  2  comprises a first waveform-transforming circuit  211 , a second waveform-transforming circuit  212  and an intermittent-pulse-wave generator  22  generating intermittent ultrasonic waves. The standard fuel pool  11  and the fuel-mix pool  12  are connected with the first waveform-transforming circuit  211  and the second waveform-transforming circuit  212  respectively. A first transducer element  111  is located at a place where the first waveform-transforming circuit  211  is connected with the standard fuel pool  11 . A second transducer element  121  is located at a place where the second waveform-transforming circuit  212  is connected with the fuel-mix pool  12 . A third transducer element  13  is located between the standard fuel pool  11  and the fuel-mix pool  12  and is connected to the intermittent-pulse-wave generator  22 . The first and the second transducer elements  111 ,  121  have corresponding equidistances to the third transducer element  13 . An end of the first transducer element  111  and an end of the second transducer element  121  are connected to an end of the comparator  3 . The comparator  3  can be an OP (operational power) amplifier, a transistor or a FLIP-FLOP circuit. Another end of the comparator  3  is connected to an end of the server  4 . An amplifier (not shown in the figure) and an A/D (analog/digital) transformer (not shown in the figure) can be further deposed between the comparator  3  and the server  4 . Another end of the server  4  is connected to a control part of the controlling device  5 . The controlling device  5  can be a uni-directional or bi-directional controlling valve or pump; and the upper and lower ways of the controlling device  5  are connected to the pure fuel pool  6  and the fuel-mix pool  12  respectively. Thus, a novel fuel-concentration detecting and controlling device for a fuel cell is obtained. 
     In the first embodiment of the present invention, an intermittent-pulse-wave signal is provided by the intermittent-pulse-wave generator  22  to excite the third transducer element  13  by transforming an electrical energy into a mechanical energy to reach the first and the second waveform-transforming circuits  111 ,  121  through the standard fuel pool  11  and the fuel-mix pool  12  respectively in a form of a longitudinal wave. The longitudinal wave can be an ultrasonic wave. The mechanical energy is then transformed back to the electrical energy to be transmitted to the first and the second waveform-transforming circuits  211 ,  212  for transforming sine wave into square wave to be transferred to the comparator  5  for a comparison. When the fuel-mix pool  12  comprises the same fuel concentration as the fuel concentration of the standard fuel pool  11 , the ultrasonic wave emitted by the third transducer element  13  reach the first and the second transducer elements  111 ,  121  at the same time without time deviation. When the fuel-mix pool  12  comprises a fuel concentration different from the fuel thickness of the standard fuel pool  11 , the ultrasonic wave emitted by the third transducer element  13  reach the first and the second transducer elements  111 ,  121  at different times with a time deviation. The value of the time deviation is obtained by the comparator  3 ; and the comparator  3  outputs a control signal to the server  4  accordingly to drive the controlling device  5  for adding fuel from the pure fuel pool  6  to the fuel-mix pool  12  so that the fuel concentration of the standard fuel pool  11  and the fuel concentration of the fuel-mix pool  12  is remain balanced. 
     Please refer to  FIG. 2 , which is a view showing a second preferred embodiment according to the present invention. As shown in the figure, the second preferred embodiment replaces the second waveform-transforming circuit  212  of the first preferred embodiment shown in  FIG. 1  with a waveform-transforming circuit  21 ; and replaces the standard fuel pool  11 , the first transducer element  111 , the third transducer element  13  and the first waveform-transforming circuit  211  of the first preferred embodiment shown in  FIG. 1  with an electronic circuit  23  setup with a default value. A thermostat is deposed at the fuel-mix pool  12  for thermo-compensation. So, the second preferred embodiment of the present invention comprises a fuel-mix pool  12 , an ultrasonic element  2 , a thermostat  14 , a comparator  3 , a server  4 , a controlling device  5  and a pure fuel pool  6 . The ultrasonic element  2  comprises the waveform-transforming circuit  21 , an intermittent-pulse-wave generator  22 , and the electronic circuit  23 . The fuel-mix pool  12  is connected to the waveform-transforming circuit  21 ; and a transducer element  121  is deposed at a place where the waveform-transforming circuit  21  is connected with the fuel-mix pool  12 . The transducer element  121  is connected to an end of the intermittent-pulse-wave generator  22 ; and another end of the waveform-transforming circuit  21  and an end of the electronic circuit  23  are connected to an end of the comparator  3 . Another end of the comparator  3  is connected to an end of the server  4 ; and another end of the server  4  is connected to a control part of the controlling device  5 . And, the upper and lower ways of the controlling device  5  are connected with the pure fuel pool  6  and the fuel-mix pool  12  respectively. 
     In the second embodiment of the present invention, an intermittent-pulse-wave signal is provided by the intermittent-pulse-wave generator  22  to excite the transducer element  121  for transforming electrical energy into mechanical energy to pass the wave signal through the fuel-mix pool  12  in a form of a longitudinal ultrasonic wave. After the ultrasonic wave is reflected back from the wall of the fuel-mix pool  12 , the ultrasonic wave is received by the transducer element  121  to be transferred to the waveform-transforming circuit  21  for transforming sine wave into square wave. The wave transformed previously and a time-base signal setup in the electronic circuit  23  for a default fuel concentration are sent together to the comparator  3  for a comparison. When the fuel concentration of the fuel-mix pool  12  is different from the default fuel concentration setup in the electronic circuit  23 , the comparator  3  outputs a control signal to the server  4  to drive the controlling device  5  for adding fuel from the pure fuel pool  6  to the fuel-mix pool  12  so that the fuel concentration of the standard fuel pool  11  and the fuel concentration of the fuel-mix pool  12  remains balanced. 
     The present invention of a fuel-concentration detecting and controlling device for a fuel cell is based on electrochemistry. Please refer to  FIG. 1 . The fuel concentration of the standard fuel pool  11  is the best fuel concentration for the fuel-mix pool  12 . Here a case when the fuel concentration of the fuel-mix pool  12  is lower than of the standard fuel pool  11  is taken. The ultrasonic wave reaches the first and the second transducer elements  111 ,  121  at different times owing to the different concentration. A comparison between the different times is done by the comparator  3  to obtain a time deviation to drive the controlling device  5  by the server  4  for adding the methanol solution with 100% concentration in the pure fuel pool  6  into the fuel-mix pool to remain the fuel concentration of the fuel-mix pool  12  being between 3.5% and 4%, the same as the fuel concentration of the standard fuel pool  11 . 
     In  FIG. 1 , the first preferred embodiment of the present invention is able to solve the problem of thermo-variation and electrode contamination by using a barrier  15  between the standard fuel pool  11  and the fuel-mix pool  12  to separate the two pools and to balance the temperatures of the two pools so that the standard fuel pool  11  and the fuel-mix pool  12  are in the same environment. In  FIG. 2 , the second preferred embodiment of the present invention uses the electronic circuit  23  and the thermostat  14  to solve the same problem. Besides, the first and the second transducer element  111 ,  121  of the first preferred embodiment are all sensors provided with tiny electricity for reducing cost and minimizing the concentration variation of the fuel-mix pool  12 ; and the sensor can be an ultrasonic element made through a micro-machine production for a volume minimization. 
     To sum up, the present invention is a fuel-concentration detecting and controlling device for a fuel cell with reduced cost, minimized volume and increased sensitivity, which controls a concentration of a fuel pool by using a time deviation caused by different concentrations. 
     The preferred embodiments herein disclosed are not intended to unnecessarily limit the scope of the invention. Therefore, simple modifications or variations belonging to the equivalent of the scope of the claims and the instructions disclosed herein for a patent are all within the scope of the present invention.