Abstract:
A refrigerant measuring and warning device includes a casing, at least one sensing element, and a detection circuit. The casing forms connectors, which are connected together by a conduit, to selectively connect to sources of refrigerant to be detected. The sensing element has an enclosure forming a connector at an end for connection with the conduit and an interior chamber communicating the connector via a pressure-dropping necked passage, a pressure detection chip and a thermocouple arranged at a top of the chamber for detecting pressure and temperature of the refrigerant to be detected. The detection circuit is housed in the casing and stores multiple sets of reference temperature and pressure for different type of refrigerants for comparison with the detected pressure and temperature, both data being displayed on a display device for visual observation and comparison. The detection circuit receives settings of alarm thresholds for the detected pressure and temperature via a keypad whereby a warning unit may issue a warning sound or voice alarm when the detected pressure and temperature reach/exceed the thresholds.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention generally relates to a refrigerant measuring and warning device and a sensing element thereof, and in particular to a refrigerant measuring and warning device that features comparison and detection of refrigerant pressure and temperature, digital display, and alarm by exceeding of thresholds. 
         [0003]    2. The Related Arts 
         [0004]    Air conditioner and refrigeration facility provides air conditioning and refrigeration by means of refrigerant that is filled in and circulates through the air conditioner or the refrigeration facility through compression-expansion cycles. Conventionally, a meter is used to detect the pressure of the refrigerant filled into the air conditioner or refrigeration system. The meter is an analog device and can only provide a single reading of the detected pressure of the filled refrigerant. Visual observation of the meter reading is not very precise and can results in significant error. Further, the conventional meter cannot detect temperature of the filled refrigerant. In addition, the conventional meter cannot provide references for the detected pressure of the refrigerant, which often causes troubles to the operator in carrying out refrigerant filling and measuring. 
         [0005]    Moreover, in case that multiple refrigerant equipments need to be monitored simultaneously during the refrigerant filling process, additional operators are required to perform a one-to-one monitoring and operation. This certainly increases the costs. Besides, the problems of incorrect reading of the meters mentioned above also induce impreciseness for the operation of refrigerant filling that may be very important in certain applications. 
         [0006]    An example of the conventional technical of refrigerant filling operation is disclosed in Taiwan Utility Model Publication No. M82088, which is also filed by the present applicant. 
       SUMMARY OF THE INVENTION 
       [0007]    Thus, an object of the present invention is to provide a refrigerant measuring and warning device comprising: a casing forming connectors for selectively connecting sources of refrigerant to be detected, the connectors being connected by a connection conduit; at least one sensing element connected to the connection conduit that connects the connectors of the casing to detect pressure and temperature of refrigerant and supply detected signals of the pressure and temperature; and a detection circuit comprising a microprocessor, a memory, a display device, a keypad, a warning unit, and a power supply device, the microprocessor having a built-in input signal conversion circuit, which is coupled to the sensing element to receive and convert the detected pressure and temperature signals for the microprocessor, the memory storing multiple sets of reference refrigerant pressure and temperature, the keypad being operable to enter selection instruction and warning instruction of pressure and temperature to the microprocessor and the display device being operable to show the detected refrigerant pressure and temperature and the reference pressure and temperature on the display for comparison, the warning unit being coupled to the microprocessor to issue an alarm when the detected refrigerant pressure and temperature reach/exceed preset warning thresholds, the power supply device powering the microprocessor, the memory, the display device, the keypad, and the warning unit. 
         [0008]    Another objective of the present invention is to provide a sensing element comprising: an enclosure having an end forming a connector for connecting a supply of refrigerant to be detected, the enclosure forming an interior chamber, which communicates the connector with a pressure-dropping necked passage to convey the refrigerant to be detected, in a pressure dropped condition, into the chamber; a pressure detection chip arranged at a top of the chamber to detect pressure of refrigerant supplied into the chamber of the enclosure; and a thermocouple arranged at the top of the chamber to detect temperature of the refrigerant supplied into the chamber of the enclosure. 
         [0009]    The refrigerant measuring and warning device allows for precise measurement, display, and monitoring of the pressure and temperature of the refrigerant to be detected and can provide multiple sets of reference pressure and temperature that are directly displayed on a display device, for comparison with the detected refrigerant pressure and temperature. Further, the device of the present invention allows for issuance of alarms when the detected pressure and temperature reach/exceed preset thresholds of pressure and temperature. Thus, the filling of the refrigerant in an air conditioner or refrigeration facility can be performed in a more precise and controlled manner. Besides, the problems of errors caused by visual observation of the conventional analog meter can be eliminated. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    In order to clearly show and make better comprehension of these and other features and advantages of the present invention, the present invention will now be described by way of examples, with reference to a preferred embodiments illustrated in the drawings, in which: 
           [0011]      FIG. 1  shows a perspective view of a refrigerant measuring and warning device constructed in accordance with the present invention; 
           [0012]      FIG. 2  shows, in cross-section, the construction of a casing and detection connectors of the refrigerant measuring and warning device of the present invention; 
           [0013]      FIG. 3  is an exploded view, partially broken, of a sensing element in accordance with a preferred embodiment of the present invention; 
           [0014]      FIG. 4  is a cross-sectional view of the sensing element shown in  FIG. 3 ; 
           [0015]      FIG. 5  is an exploded view, partially broken, of a sensing element in accordance with another embodiment of the present invention; 
           [0016]      FIG. 6  is a block diagram of a detection circuit of the refrigerant measuring and warning device in accordance with the present invention; 
           [0017]      FIG. 7  is a block diagram of an input signal conversion circuit that forms in part a microprocessor of the detection circuit shown in  FIG. 6 ; 
           [0018]      FIG. 8  shows an example layout of a display device and a keypad of the refrigerant measuring and warning device of the present invention; 
           [0019]      FIG. 9  shows another application of the sensing element of the present invention; and 
           [0020]      FIG. 10  is a block diagram of a detection circuit of the refrigerant measuring and warning device in accordance with another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0021]    With reference to the drawings and in particular to  FIGS. 1 and 2 , a refrigerant measuring and warning device constructed in accordance with the present invention, generally designated with reference numeral  100 , comprises a casing  10 , at least one sensing element  20 , and a detection circuit  30 . The casing  10  is provided with a plurality of detection connectors  11 ,  12 ,  13 , which provide connection with refrigerant to be detected. The detection connectors  11 ,  12 ,  13  are connected together with a connection conduit  14 . 
         [0022]    Also referring to  FIGS. 3 and 4 , the sensing element  20 , which is constructed in accordance with a first embodiment of the present invention, is shown. The sensing element  20  comprises an enclosure  21 , a pressure detection chip  22 , and a thermocouple  23 . An end of the enclosure  21  forms a connector  211  and an opposite end forms an inner-threaded opening  212 . The connector  211  connects to the connection conduit  14  that is arranged inside the casing  10 . In the embodiment illustrated, two sensing elements  20  are provided and the connectors  211  of the sensing elements  20  connect to respective ends of the connection conduit  14 . It is apparent that the sensing element  20  can be connected to any position along the connection conduit  14  without departing from the spirit of the present invention. The inner-threaded opening  212  forms thread  212   a  on an inside wall (not labeled) thereof to engage and retain a threaded closing member  212   b  inside the opening  212 . 
         [0023]    The enclosure  212  forms an interior chamber  213 , which communicates the connector  211  with a pressure-dropping necked passage  214 . The passage  214  has an inside diameter that is much smaller than those of the connector  211  and the interior chamber  213 . The refrigerant to be detected is supplied into the interior chamber  213  through the passage  214  after being subject to pressure dropping caused by the necked passage  214 . 
         [0024]    The pressure detection chip  22  is mounted to a bottom face (not labeled) of the threaded closing member  212   b . The pressure-detection chip  22  comprises a detection end  221  and an opposite end forming terminals  222 . The detection end  221  faces toward bottom of the chamber  213  to detect the pressure of the refrigerant supplied into the chamber  213  and, in response thereto, generates a pressure detection signal corresponding to the detection of pressure. The terminals  222  extend through the threaded closing member  212   b  to output the detected pressure detection signal. 
         [0025]    The thermocouple  23  is arranged on the bottom face of the threaded closing member  212   b  and faces toward the bottom of the chamber  213  to detect the temperature of the pressure-dropping refrigerant that is supplied into the chamber  213  and generates a corresponding temperature detection signal. The thermocouple  23  has a pair of terminals  231  for outputting the temperature detection signal and the terminals  231  extend through the threaded closing member  212   b.    
         [0026]    Referring to  FIG. 5 , which shows another embodiment of the present invention, in which the pressure-detection chip  22  and the thermocouple  23  are mounted on a single control circuit board  24 , the single control circuit board  24  has pressure-detection signal terminals  241  that are connected to the terminals  222  of the pressure-detection chip  22  and temperature-detection signal terminals  242  that are connected to the terminals  231  of the thermocouple  23  and the terminals  241  and  242  extend through the threaded closing member  212   b.    
         [0027]    Referring to  FIGS. 6 and 7 , wherein  FIG. 6  shows a block diagram of the detection circuit  30  of the refrigerant measuring and warning device  100 , which illustrates only an example of the circuit that embodies the present invention, and should not be construed as limitation to the present invention, the detection circuit  30  is arranged inside the casing  10  and comprises a microprocessor  31 , a memory  32 , a display device  33 , a keypad  34 , a warning unit  35 , and a power supply device  36 . The microprocessor  31  is built therein with an input signal conversion circuit  311 , which can be of any known circuit, and may comprise, in the embodiment illustrated, amplifiers  311   a ,  311   b ,  311   c , a level transformation circuit  311   d , and an analog-to-digital converter  311   e , as shown in  FIG. 7 . The amplifiers  311   a ,  311   b  are connected to the terminals  222  of the pressure-detection chip  22  of the sensing element  20  to amplify the pressure detection signal of the refrigerant supplied to the chamber  213  and apply the amplified signal to the analog-to-digital converter  311   e  where the amplified signal, which is originally analog, is converted into corresponding digital signal for output. 
         [0028]    The level transformation circuit  311   d  can be of any know type, and comprises, in the embodiment illustrated, a circuit comprised of transistors and/or thyristors for transformation of voltage level of an input signal. The level transformation circuit  311   d  is coupled to the terminals  231  of the thermocouple  23  of the sensing element  20  to receive the temperature detection signal of the refrigerant supplied to the chamber  213  and transforms the voltage level of the temperature detection signal. The level transformation circuit  311   d  is also coupled to the amplifier  311   c , which amplifies the transformed temperature detection signal and applies the amplified and transformed temperature detection signal, which is originally analog, to the analog-to-digital converter  311   e  to provide a corresponding digital signal for output. 
         [0029]    The analog-to-digital converter  311   e  is coupled to the microprocessor  31  to supply the digital signals of pressure and temperature of the refrigerant to the microprocessor  31  for subsequent processing. 
         [0030]    Software or programs for converting and displaying the refrigerant pressure and temperature are built in the microprocessor  31  for processing the digital data of the refrigerant pressure and temperature from the analog-to-digital converter  311   e  to form data that can be displayed on the display device  33 . 
         [0031]    Sets of different standard data or reference data of refrigerant pressure and temperature are stored in the memory  32  that is coupled to the microprocessor  31  whereby the microprocessor  31  may issue instructions to the memory  32  for access or retrieve a selected set of standard data of refrigerant pressure and temperature from the memory  32 . 
         [0032]    Also referring to  FIG. 8 , the display device  33  can be of any type, and may comprise, in the embodiment illustrated, a liquid crystal display (LCD) device. Apparently, other equivalent display devices, such as light-emitting diode (LED) display and cathode ray tube (CRT) display, are within the scope of the present invention. The display device  33  comprises a LCD drive circuit  331 , a display panel  332 , and a backlight drive circuit  333 . The LCD drive circuit  331  and the backlight drive circuit  333  are coupled to the microprocessor  33  to receive from the microprocessor  33 , the refrigerant pressure and temperature of the refrigerant supplied to the chamber  213 , as well as those data retrieved from the memory  32 . The data are displayed on the display panel  332 .  FIG. 8  illustrates an example of the display panel  332 , which comprises a left section that shows the pressure and the temperature of the refrigerant detected and a right section that shows corresponding reference data or standard data of refrigerant pressure and temperature for immediate comparison. 
         [0033]    The keypad  34  is coupled to the microprocessor  31  and can be of any type, such as thin-film touch-control keypad that is taken as an example for explanation purposes herein.  FIG. 8  shows an example of the keypad  34 , comprising buttons  341 ,  342 ,  343 ,  344 ,  345 ,  346 ,  347 ,  348 , which are a power button, a unit system conversion button, a refrigeration type selection button, a reset button, a backlight setting display button, a memory button, a memory clearing button, and a warning setting button, respectively, for manual input of instruction or data related to power, conversion of unit system, selection of refrigerant type, resetting, backlight setting display, memory, memory clearing, and warning setting. Apparently, this button can be configured in different ways. It is noted that the warning setting button  348  is provided for selective actuation and setting of warning levels of refrigerant pressure and temperature to the microprocessor  31 , which serve as thresholds for issuing alarm for the pressure and temperature of the refrigerant supplied to the sensing element  20 . 
         [0034]    The warning unit  35  is coupled to the microprocessor  31  and is connected to an alarm device  351 , which can be of any type, and is embodied as a buzzer in the embodiment illustrated. When the pressure and/or temperature of the refrigerant to be detected reach the thresholds or warning settings given by the warning setting button  348  of the keypad  34 , the microprocessor  31  signals the warning unit  35  to actuate the alarm device  351 , which then gives off an alarm, which can be a single tone or a voice alarm or any combination thereof. 
         [0035]    The power supply device  36  can be of any type, and is comprised of a battery set of direct current, as shown in the embodiment illustrated. Other equivalent power supplies, such as direct-current adaptor for a household electric main, are apparently within the scope of the present invention. The power supply device  36  supplies power to the sensing element  20 , the microprocessor  31 , the memory  32 , the display device  33 , the keypad  34 , and the warning unit  35 . 
         [0036]    In practical use of the refrigerant measuring and warning device  100 , setting and actuation of power, conversion of unit system, selection of refrigerant type, resetting, backlight setting display, memory, memory clearing, and warning setting are operated through the buttons  341 ,  342 ,  343 ,  344 ,  345 ,  346 ,  347 ,  348  of the keypad  34 . The refrigerant measuring and warning device  100  provides a display that allows for comparison between the detected refrigerant pressure and temperature and reference or standard pressure and temperature and also an alarm may be issued by the alarm device  351  that is actuated by the warning unit  35  under the control of the refrigerant measuring and warning device  100 , if the detected values of the pressure and temperature reach/exceed preset thresholds. 
         [0037]    Referring to  FIG. 9 , which shows another application of the sensing element  20 , in the application, the sensing element  20  is housed in a casing  10 ′. The casing  10 ′ also houses the detection circuit  30 . A display  33 ′ is provided on the casing  10 ′ to display detected refrigerant pressure and temperature and reference or standard pressure and temperature, as well as thresholds for pressure and temperature. A plurality of buttons  341   a ,  342   a ,  343   a ,  344   a  are provide on a surface of the casing  10 ′ for performing setting and operation of power, backlight displaying, switching of refrigerant pressure and temperature, and switching of function to thereby provide a simplified, single-input refrigerant measuring and warning device  100 ′ that still realize the above discussed functions of comparison and display of the detected refrigerant pressure and temperature and reference or standard pressure and temperature and the thresholds of pressure and temperature, as well as setting of the thresholds of pressure and temperature. 
         [0038]    Referring to  FIG. 10 , which shows another embodiment of the detection circuit  30 , in the illustrated detection circuit  30 , the pressure detection chip  22  of the sensing element  20  is coupled to a constant current source  37 . The constant current source  37  is connected to a power supply device  36  to provide a constant current to the pressure detection chip  22  in order to eliminate errors caused by variation of current induced by external temperature or temperature rise occurring in the circuit whereby more precise detection of the refrigerant supplied to the sensing element  20  by the pressure detection chip  22  can be effected. 
         [0039]    Although the present invention has been described with reference to the preferred embodiments thereof, it is apparent to those skilled in the art that a variety of modifications and changes may be made without departing from the scope of the present invention which is intended to be defined by the appended claims.