Abstract:
The present invention is a hand held gauge for use with refrigeration systems. The gauge includes a service port connector, a display screen, and user interfacing buttons. The gauge also includes electronic storage of the pressure-to-saturation temperature data for different refrigerants. The gauge allows for the measuring of temperature and pressure of refrigeration systems. After a user inputs a refrigerant type, the gauge uses the pressure and the saturation data to determine the saturation temperature. The saturation temperature is compared to the measured temperature to get the superheat or subcooling. These results may all be displayed on the display screen.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to electronic hand held gauges, particularly for measuring pressure and temperature, particularly for refrigeration systems. 
       BACKGROUND OF THE INVENTION 
       [0002]    In a common refrigeration process, a refrigerant starts in the form of a vapor at or slightly above ambient temperature. This vapor enters a compressor and exits the compressor at a high temperature and high pressure. This vapor then travels under pressure through a condenser. The condenser comprises a series of tubes that are passively cooled by air, water, or glycol. By traveling through the condenser, the vapor is brought to a lower temperature, but remains at a high pressure. Because of this, the vapor becomes a liquid. When this liquid exits the condenser and passes through a type of restriction, the pressure suddenly decreases. The evaporation and expansion of the liquid causes a large decrease in temperature and pressure. This now cold vapor passes through the tubes of an evaporator. A fan blows ambient air over the cold tubes of the evaporator, which produces cooled air. 
         [0003]    At the liquid outlet of the condenser, it is expected that only liquid refrigerant will be present. The number of degrees that the liquid temperature is cooler than the saturation temperature corresponding to the liquid pressure is called the liquid subcooling. The subcooling is a measure of the effectiveness of the condenser and relates to proper refrigerant charge. 
         [0004]    At the outlet of the evaporator, it is expected that only vapor refrigerant will be present. The number of degrees that the vapor temperature is warmer than the saturation temperature corresponding to the vapor pressure is called the superheat. The superheat is a measure of the effectiveness of the evaporator and relates to the refrigerant charge. 
         [0005]    The saturation temperature, as mentioned above, corresponds to a pressure of the refrigerant. If the pressure of the refrigerant and the type of refrigerant is known, the saturation temperature may be determined. Different refrigerants have different relationships between pressure and saturation temperature, but for a given refrigerant, a chart or formula may readily express the relationship. 
         [0006]    Therefore, in order to calculate the superheat or subcooling of a refrigeration system, a user must first know the type of refrigerant and the pressure of the refrigerant in the refrigeration system. Then the user must determine the saturation temperature using the measured pressure and the chart or formula corresponding to the known refrigerant. Then the user must measure the actual temperature of the refrigerant and compare this value to the determined saturation temperature. To determine the subcooling, the user by subtract the actual refrigerant temperature from the saturation temperature, and to determine the superheat, the user would subtract the saturation temperature from the actual refrigerant temperature. 
         [0007]    Refrigeration systems may be provided with service ports as a means to take these measurements. These service ports may be at one or more locations to provide the user access to both the refrigerant in the condenser and the evaporator. 
         [0008]    Hand held refrigeration gauges are known to provide refrigeration details and information to a user such as disclosed by U.S. Pat. No. 6,898,979. However, not all the necessary features for accurate subcooling and superheat determination are disclosed. The gauge disclosed does not provide a temperature sensor, but only a pressure sensor. In addition, the gauge disclosed does not provide a user interface. Also, the gauge disclosed does not provide means by which a user may interact with the operations and calculations of the gauge. 
         [0009]    The present inventor has recognized the need for a refrigeration gauge that may be held in the hand of a user. 
         [0010]    The present inventor has further recognized the need for a refrigeration gauge that has an easy-to-use user interface. 
         [0011]    The present inventor has further recognized the need for a refrigeration gauge that may measure both pressure and temperature. 
         [0012]    The present inventor has further recognized the need for a refrigeration gauge that may, given the necessary data, calculate values for superheat and/or subcooling. 
         [0013]    The present inventor has further recognized the need for a refrigeration gauge that may accept types of input from the user. 
       SUMMARY OF THE INVENTION 
       [0014]    The present invention comprises a hand held refrigeration gauge for use with a refrigeration system. The hand held refrigeration gauge includes a digital display screen on which a user may see outputs of the gauge. The outputs shown on this digital display may include, but are not limited to, temperature, pressure, saturation temperature, superheat, or subcooling. In addition, this digital display may show other information such as the current progression through the measuring and calculating process, or a notification when it is time for user input. 
         [0015]    In one embodiment, the gauge has at least one probe that measures pressure and temperature. One probe can be used to, at different times or simultaneously, measure both pressure and temperature. Alternatively, two probes may be included on the hand held gauge, with one measuring pressure and the other measuring temperature. These values may then be displayed on the digital display screen of the hand held gauge. 
         [0016]    The present invention also includes a processor for performing calculations such as subcooling and superheat and RAM for storing input and output data. This processor comprises taking a user input of refrigeration type. In addition, a measurement of the pressure of the vapor or liquid is made. Also, a chart or formula corresponding to the given refrigeration type is referenced, and a saturation temperature is determined. Furthermore, a measurement of the temperature of the vapor or liquid is made. Then, if a value of subcooling is desired, the measured temperature is subtracted from the saturation temperature. Alternatively, if a value of superheat is desired, the saturation temperature is subtracted from the measured temperature. These values may then be displayed on the digital display screen of the hand held gauge. 
         [0017]    The present invention also includes at least one button or other information transferring mechanism that allows the user to control elements of the internal process of the hand held gauge. This may comprise a button to switch between performing a calculation of superheat or subcooling. In addition, this may comprise a number of buttons to select what type of refrigerant is being used, A menu button may bring up a list of refrigerants on the digital display screen, and up and down buttons as well as a select button would allow for the choosing of a refrigerant type. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a perspective view of the hand held refrigeration gauge of the present invention; 
           [0019]      FIG. 2  is a schematic view of the internal processes of the present invention; 
           [0020]      FIG. 3  is a perspective view of another embodiment of the hand held refrigeration gauge of the present invention; and 
           [0021]      FIG. 4  is a schematic view of the superheat/subcooling calculation process of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]    While this invention is susceptible of embodiment in many different forms, there are shown in the drawings, and will be described herein in detail, specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the specific embodiments illustrated. 
         [0023]      FIG. 1  shows the preferred embodiment of the hand held refrigeration gauge  100  of the present invention. The gauge has a body  110 , a digital display screen  160 , function buttons  130 , a read button  140 , a hand grip  120 , and a service port connector  150 . 
         [0024]    The service port connector  150  is for engaging a service port of a refrigeration or air conditioning system. In operation, the service port connector  150  is fitted onto the service port of a refrigeration or air conditioning system to be measured so as to guide the refrigerant pressure and/or temperature from the service port into the gauge  100 . The service port has a seal not shown) for sealing the connection between the service port connector  150  and the service port. Pressure and/or temperature is measured upon depression of the operation function button  140 . The pressure or temperature may be displayed on the digital display screen  160 , by way of a processor  210  of the gauge  100 . 
         [0025]    In one embodiment, the gauge  100  has a projection  154  for engaging a shrader valve on the service port of the system that the gauge  100  is connected. The read button  140  is electronically or mechanically connected to the projection  154 . The read button  140  has a withdrawn position and a read position. The projection  154  has a withdrawn position and a read position, corresponding to the withdrawn position and the read position of the read button  140 . The read button  140  is movable in the A direction and the projection  154  is movable in the B direction. When the button  140  is pressed downward to the read position, the projection  154  is pressed downward and when the service port connector  150  is engaged with a service port, the projection  154  will engage a shrader valve of the service port to allow pressure to enter the gauge  100 . 
         [0026]    The body  110  contains a pressure sensor  170  in fluid communication with the service port connector  150 . The pressure sensor  170  is responsive to pressure at the service port connector  150  to generate an electrical output representative of the pressure at service port connector  150 . 
         [0027]    In one embodiment, the pressure sensor  170  is a mechanical device that measures pressure mechanically and displays the results digitally, such as disclosed in U.S. Pat. No. 6,530,281, which is herein incorporated by reference. In another embodiment, the pressure sensor  170  is an electronic pressure transducer, such as a piezosensor, that generates an electrical signal in response to the pressure to which the transducer is exposed, such as disclosed in U.S. Pat. No. 7,410,257, which is herein incorporated by reference. The electrical signal is then presented on the digital display screen  160  by way of processor  210 . 
         [0028]    In one embodiment, gauge  100  has a temperature sensor  180 . Temperature sensor  180  may, like pressure sensor  170 , be in fluid communication with the service port connector  150 . The temperature sensor  180  is responsive to temperature at the service port connector  150  to generate an electrical output representative of the temperature at service port connector  150 . Whenever the refrigerant is released to be exposed to the pressure sensor  170  by means of service port connector  150 , the refrigerant may also be exposed to a temperature sensor  180 . However the gauge is not required to measure the pressure in order to measure temperature; either function may operate separately or in concert. Temperature sensor  180  may be in the same or a different location as pressure sensor  170 . 
         [0029]    In another embodiment, shown in  FIG. 3 , the temperature sensor  181  is attached or enclosed in a compartment of the body  110 . The temperature sensor  181  is attached to the gauge  100 . The temperature sensor  181  is detachable from the body  110  so that a user may connect or touch the temperature sensor  181  to a component of the air conditioning or refrigeration system being measured. 
         [0030]    As shown in  FIG. 2 , the pressure sensor  170  and temperature sensor  180  send signals to a processor  210 . A signal from a user input device  212  may also be sent to the processor  210 . User input device  212  is operable to detect commands from a user at the device. User input device  212  could include a button, such as function buttons  130 , a keypad, a touch screen, a stylus, a microphone, and/or any other appropriate device. Processor  210  is typically responsible for responding to the commands. 
         [0031]    The processor  210  is operable to receive signals, analyze them, and generate representative signals as the output  260  to be sent to the display screen  160 . Processor  210  may, for example, accomplish this by determining a set of pulses that represent the signals from the pressure sensor  170  or temperature sensor  180 . 
         [0032]    The processor  210  may also make calculations using the data provided by the sensors and inputs. One of such calculations is the superheat and/or subcooling of the refrigeration system. In order to calculate these values, the processor  210  calculates the saturation temperature and actual temperature of the refrigerant. To do so, the processor  210  takes as an input the pressure of the refrigerant. The processor  210  also contains an electronic data storage  220  which contains known relationships between pressure and saturation temperature for different refrigerants. The data can be in the form of a pressure-to-saturation temperature table or coefficients for a polynomial or other type of equation, for one or more particular types of refrigerants. Based on the coefficients the processor can determine the saturated temperature as a function of the input pressure. U.S. Pat. No. 5,627,770, which is herein incorporated by reference, discloses such a pressure-to-saturation temperature table and a coefficient calculation. 
         [0033]    The processor  210  calculates the saturation temperature of the refrigerant eased on the measured pressure and the relationship table or equation information in the storage  220 . To obtain a superheat value, the processor  210  subtracts the saturation temperature from the measured temperature. Similarly, to calculate a subcooling value, the processor subtracts the actual temperature from the saturation temperature. Processor  210  may also calculate other pressure or temperature related data, such as exception reports. The processor may send one or more of these values to the digital display screen  160  as an output to the user. 
         [0034]      FIG. 4  shows one type of superheat or subcooling calculation function in more detail. At step  402 , the processor or data storage receives a refrigerant type value from the user comprising the type of refrigerant to be measured. In one embodiment, the device at step  402  may also be preprogrammed to operate with one specific refrigerant such that user input at step  402  is not required. At step  404  the processor or data storage receives a pressure value corresponding to the pressure of the system being measured and received from the gauge taking the pressure measurement. 
         [0035]    At step  406 , a temperature value is received into the data storage or the processor. The temperature value may be generated by a measurement from the temperature sensor  180  or  181 . Alternatively, the temperature value may be received as an input, such as from a user through function buttons  130  or through another user input  212 . 
         [0036]    At step  408  the processor references a predefined pressure-to-saturation temperature table to obtain a saturation temperature based on the refrigerant type value. The pressure-to-saturation table contains a number of saturation temperature values each corresponding to a given refrigerant type. In one embodiment, the table contains one saturation temperature value for each refrigerant type. Alternatively, in step  208  the processor data stored in the form of coefficients for a polynomial or other types of equation whereby the processor can evaluate the saturated pressure as a dependant variable, as a function of the pressure value being an independent variable. The processor at step  408  produces a value corresponding to the saturation temperature. 
         [0037]    At step  410  the processor receives a supersub value corresponding to the desired output of superheat or subcooling. This supersub value maybe predefined or may be received as an input, such as from a user, either before or at step  410 . If the supersub value corresponds to superheat, the process proceeds to step  412 . If the supersub value corresponds to subcooling, the process proceeds to step  414 . At step  412 , the processor gauge subtracts the saturation temperature value from the measured temperature value to get a superheat output value corresponding to the difference between the refrigerant and the measured temperature. If subcooling has been selected, at step  414 , the processor subtracts the measured temperature value from the saturation temperature value to get a subcooling output value, corresponding to the difference between the measured temperature and the saturation temperature. Once the output value for superheat or subcooling is determined in step  412  or step  414 , respectively, step  416  is initiated. At step  416 , the processor directs the output corresponding to the determined superheat or subcooling to be outputted. At step  416 , the output may including the output being displayed on the display  160  or the output device  260 . 
         [0038]    The processor  210  also has instructions for calculating and displaying the proper pressure range for a particular refrigerant type based on given information, such as, the ambient air temperature, indoor wet bulb temperature, and refrigerant type. Input information necessary to calculate such information may be entered by a user using the function buttons  130  or through another user input  212 . 
         [0039]    The gauge  100  may have a user output device  260 . The user output device  260  is operable to present information, whether about pressure, the device, or otherwise, to a user at the gauge  100 . In one embodiment, the output device is the display  160 . However, the information may be presented in visual, audible, tactile, or other appropriate format. 
         [0040]    Although  FIG. 2  illustrates the components for a refrigeration gauge, other refrigeration gauges may include less, more, and/or a different arrangement of components. For example, a refrigeration gauge may not include a user input device and/or a user output device. 
         [0041]    In one embodiment, the display  160  comprises a pressure display area, a temperature display area, and a superheat/subcooling display area. While  FIG. 1  and  FIG. 2  show the display comprising one screen, various display types are encompassed within the invention. The pressure display and temperature display maybe shown by a numerical display where each digit is shown in its own LED display. Alternatively, all of the display information may be presented on a single screen, such as an LCD display. 
         [0042]    While particular sequences are show and described herein, one skilled in the art will recognize that where a step requires information to be received from a measurement of the device or from an input by a user, the device  100  may receive that measurement or input at an earlier point in time and hold the information in a memory of the device until that information is needed by the device or a function of the device  100 . The electronic components may be powered by a power source (not shown) which may comprise a battery, photovoltaic cell, or other power source. One of the function buttons  130  may operate a power button for turning the gauge on or off. 
         [0043]    In the illustrated embodiment, the processor  210  can be implemented as a programmed general purpose computer, or a single special purpose integrated circuit (e.g., ASIC) having a main or central processor section for overall, system-level control, and separate sections dedicated to performing various different specific computations, functions and other processes under control of the central processor section. The processor  210  can be a plurality of separate dedicated or programmable integrated or other electronic circuits or devices (e.g., hardwired electronic or logic circuits such as discrete element circuits, or programmable logic devices such as PLDs, PLAs, PALs or the like). The processor  210  can be implemented using a suitably programmed general purpose computer, e.g., a microprocessor, microcontroller or other processor device (CPU or MPU), either alone or in conjunction with one or more peripheral (e.g., integrated circuit) data and signal processing devices. In general, any device or assembly of devices on which a finite state machine capable of implementing the procedures described herein can be used as the processor  210 . 
         [0044]    From the foregoing, it will be observed that numerous variations and modifications may be effected without departing from the spirit and scope of the invention. It is to be understood that no limitation with respect to the specific apparatus illustrated herein is intended or should be inferred.