Abstract:
According to one embodiment, a CNG dispenser is provided that includes a user-actuatable button for allowing selection of a pressure to which to fill a vehicle tank with CNG, and a controller for opening a high pressure fill valve to dispense high pressure CNG into the vehicle tank while monitoring the pressure of the vehicle tank until the pressure reaches the user-selected pressure. According to another embodiment, the controller is operable in a selected one of two modes of operation. The two modes of operation include a one-pressure bank operation mode in which only the input of a high pressure fill valve is coupled to a CNG supply line, and a three-pressure bank operation mode in which the inputs of each of three fill valves are coupled to respective CNG supply lines. A graphic fuel gage may be provided on the dispenser payment terminal screen.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61/793,754, filed on Mar. 15, 2013, entitled “IMPROVED CNG DISPENSER,” by Sarah Ann Lambrix et al., the entire disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention generally relates to dispensers for dispensing compressed natural gas (CNG) to vehicles. 
     SUMMARY OF THE INVENTION 
     According to an embodiment of the present invention, a CNG dispenser is provided comprising: a cabinet; a fill hose extending from the cabinet; a pressure sensor disposed to sense a pressure within the fill hose that corresponds to a pressure of a vehicle tank when the fill hose is coupled to the vehicle tank; a high pressure fill valve disposed between a high pressure CNG supply line and the fill hose; at least one user-actuatable button disposed on the cabinet for allowing a user to select a pressure to which to fill the vehicle tank with CNG; and a controller coupled to the at least one user-actuatable button, the pressure sensor, and the high pressure fill valve for opening the high pressure fill valve to dispense high pressure CNG into the vehicle tank while monitoring the pressure of the vehicle tank as sensed by the pressure sensor until the pressure reaches the user-selected pressure. 
     According to another embodiment of the present invention, a CNG dispenser is provided comprising: a cabinet; a fill hose extending from the cabinet; a pressure sensor disposed to sense a pressure within the fill hose that corresponds to a pressure of a vehicle tank when the fill hose is coupled to the vehicle tank; a low pressure fill valve having an input configured to be coupled to a lower pressure CNG supply line, and an output coupled to the fill hose; a medium pressure fill valve having an input configured to be coupled to a medium pressure CNG supply line, and having an output coupled to the fill hose; a high pressure fill valve having an input configured to be coupled to a high pressure CNG supply line, and having an output coupled to the fill hose; and a controller coupled to the pressure sensor, and the low, medium, and high pressure fill valves, wherein the controller is operable in a selected one of two modes of operation that may be selected by an operator of a filling station where the CNG dispenser is located, the two modes of operation include a one-pressure bank operation mode in which only the input of the high pressure fill valve is coupled to a CNG supply line, and a three-pressure bank operation mode in which the inputs of each of the fill valves are coupled to respective CNG supply lines. 
     These and other features, advantages, and objects of the present invention will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a hydraulic flow diagram in schematic form of CNG flow control components of a dispenser according to some of the embodiments; 
         FIG. 2  is an electrical circuit diagram in block form of electrical components of a dispenser according to some of the embodiments; 
         FIG. 3  is an elevational view of a front of a CNG dispenser in which the embodiments described herein are implemented; 
         FIG. 4  is an elevational view of a close-up of a portion of the front of the CNG dispenser of  FIG. 3 ; 
         FIG. 5  is an elevational view of a display of the CNG dispenser of  FIG. 3  showing a graphic fill indicator; 
         FIG. 6  is a hydraulic flow diagram in schematic form of CNG flow control components of a dispenser according to an alternative embodiment; 
         FIG. 7  is a hydraulic flow diagram in schematic form of CNG flow control components of a dispenser according to an another alternative embodiment; and 
         FIG. 8  is a hydraulic flow diagram in schematic form of CNG flow control components of a dispenser according to another alternative embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the present preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. In the drawings, the depicted structural elements are not to scale and certain components are enlarged relative to the other components for purposes of emphasis and understanding. 
       FIG. 1  is a hydraulic flow diagram showing the CNG hydraulic components  210   a  of a dispenser  205  ( FIG. 3 ). There are typically two to four lines that run between a dispenser and the pressure banks of a natural gas farm where the CNG is typically stored in one or three pressure banks. In typical CNG dispensers that are used with a one-pressure bank system, these lines include a vent line  252  and a supply line  216  that supplies CNG at a single high pressure to the dispenser. If the CNG dispensers are used with a three-pressure bank system, these lines include a vent line  252 , and a first supply line  212  that supplies CNG at a first pressure to the dispenser, a second supply line  214  that supplies CNG at a second pressure (higher than the first pressure), and a third supply line  216  that supplies CNG at a third pressure (higher than the first and second pressures). Natural gas farms often store CNG at multiple pressures due to the cost of storing CNG at the high pressures (i.e., 3000 to 3600 psi) required for vehicles. More specifically, a natural gas farm may store CNG in a first pressure bank at 2000 psi, in a second pressure bank at 3000 psi, and in a third pressure bank at 4000 psi. When filling a vehicle tank up to 3600 psi, for example, CNG is first drawn off the first pressure bank through first supply line  212  until the vehicle tank is partially filled at 2000 psi, then CNG is drawn off the second pressure bank through second supply line  214  until the vehicle tank is partially filled at 3000 psi, and then CNG is drawn off the third pressure bank through third supply line  216  until the vehicle tank is completely filled at 3600 psi. The actual pressure at which the vehicle is filled may depend on ambient temperature as discussed further below. Because the CNG in the lower-pressure first and second pressure banks costs less to supply, the cost of filling a vehicle tank is reduced by filling the vehicle as much as possible by initially using the lower pressure first and second pressure banks to partially fill the vehicle tank. 
     Some of the embodiments described below provide a CNG dispenser  205  that may be configured with software to operate with either a one-pressure bank system or a three-pressure bank system. In this manner, a filling station would not have to switch CNG dispensers  205  when changing from a one-bank system to a three-bank system or vice versa. 
     Dispenser  205  further includes manual shut-off valves  218 ,  220 , and  222  on supply lines  212 ,  214 , and  216 , respectively. Each of supply lines  212 ,  214 , and  216  further includes a filter  224 ,  226 , and  228 , respectively. After filtration, each of supply lines  212 ,  214 , and  216  is split into first and second branches  212   a  and  212   b ,  214   a  and  214   b , and  216   a  and  216   b , where the two branches are provided for the two vehicle fill hoses  230   a  and  230   b  that are positioned on either side of dispenser  205  (see also  FIG. 3 ). In a typical CNG dispenser  205 , one fill hose  230   a  is configured for supplying pressure to 3000 psi and the other fill hose  230   b  is configured for supplying pressure to 3600 psi. In some cases, a nozzle on fill hose  230   a  is shaped differently than a nozzle on fill hose  230   b . For example, fill hose  230   a  may have a nozzle that is shaped to fit a vehicle fill connector of a vehicle that runs on CNG at a pressure of 3000 psi while fill hose  230   b  may have a nozzle that is shaped to fit a vehicle fill connector of a vehicle that runs on CNG at a pressure of 3600 psi. This is to prevent users from inadvertently using the wrong fill hose and filling their tank to the wrong pressure. However, having different fill hoses that operate at different predetermined pressures limits the number of available fill hoses at a filling station and makes it difficult for a user to pull up to a dispenser that may be available on one side only to find out that the fill hose needed is already in use at the other side of the dispenser  205 . One embodiment addresses this problem by providing a CNG dispenser  205  that allows the user to select a pressure to be delivered through any one fill hose  230   a ,  230   b . In other words, dispenser  205  may be configured to allow selection of a “grade” of CNG having either 3000 psi or 3600 psi to be dispensed through a single fill hose  230   a ,  230   b . In this regard, fill hose  230   a  may have a nozzle  232   a  that is shaped to fit either of the available vehicle fill connector styles, and fill hose  230   b  may have a nozzle  232   b  that is also shaped to fit either of the available vehicle fill connector styles. 
     The first branches  212   a ,  214   a , and  216   a  of supply lines  212 ,  214 , and  216  include a respective low pressure fill valve  238   a , medium pressure fill valve  240   a , and high pressure fill valve  242   a . Likewise, the second branches  212   b ,  214   b , and  216   b  of supply lines  212 ,  214 , and  216  include a respective low pressure fill valve  238   b , medium pressure fill valve  240   b , and high pressure fill valve  242   b . The outputs of valves  238   a ,  240   a , and  242   a  are coupled to a first manifold  236   a  that connects first branches  212   a ,  214   a , and  216   a  with a first fill line  234   a , which is coupled to first fill hose  230   a . The outputs of valves  238   b ,  240   b , and  242   b  are coupled to a second manifold  236   b  that connects second branches  212   b ,  214   b , and  216   b  with a second fill line  234   b , which is coupled to second fill hose  230   b.    
     Each of valves  238   a ,  240   a ,  242   a ,  238   b ,  240   b , and  242   b  are selectively and independently opened and closed under control of a dispenser controller  110  ( FIG. 2 ). In this manner, only one of valves  238   a ,  240   a , and  242   a  is opened at any one time to supply CNG at selected pressure through first fill hose  230   a . Similarly, only one of valves  238   a ,  240   a , and  242   a  is opened at any one time to supply CNG at a selected pressure through second fill hose  230   a.    
     Valves  238   a ,  240   a ,  242   a ,  238   b ,  240   b , and  242   b  may be pneumatically-actuated hydraulic valves, which are controlled by controller  110  via respective actuator valves  239   a ,  241   a ,  243   a ,  239   b ,  241   b , and  243   b  ( FIG. 2 ). These actuator valves  239   a ,  241   a ,  243   a ,  239   b ,  241   b , and  243   b  may be electrically-actuated pneumatic valves. The use of such a valve system allows the pneumatically-actuated hydraulic valves  238   a ,  240   a ,  242   a ,  238   b ,  240   b , and  242   b  to be located in the hazardous area of dispenser  205  and the electrically-actuated pneumatic actuator valves  239   a ,  241   a ,  243   a ,  239   b ,  241   b , and  243   b  to be located in the electrical portion of a cabinet  206  ( FIG. 3 ) of dispenser  205 , thus isolating the hazardous area from any electrical lines. Alternatively, fill valves  238   a ,  240   a ,  242   a ,  238   b ,  240   b , and  242   b  may be electrically-operated explosion proof valves thereby eliminating the need for the electrically-actuated pneumatic actuator valves  239   a ,  241   a ,  243   a ,  239   b ,  241   b , and  243   b.    
     A first meter  244   a  is provided in fill line  234   a  for measuring the CNG flowing through it. A second meter  244   b  is provided in fill line  234   b  for measuring the CNG flowing through it. As discussed further below, meters  244   a  and  244   b  are electrically coupled to dispenser controller  110  ( FIG. 2 ), which reads meter data during various periods of operation. 
     A first digital pressure sensor  246   a  is also provided in first fill line  234   a  proximate first vehicle fill hose  230   a  for providing pressure readings to controller  110 . When filling a vehicle tank using first fill hose  230   a , controller  110  may first reads a selected pressure as determined by which grade the user selected by pressing a grade select button  128  (if provided) corresponding to the desired pressure. Controller  110  then opens first low pressure fill valve  238   a  while keeping closed first medium pressure valve  240   a  and first high pressure valve  242   a  such that CNG from the low pressure bank supplied via first supply line  212  is dispensed to the vehicle tank. Controller  110  monitors the pressure readings from first digital pressure sensor  246   a , which correspond to the pressure in the vehicle tank when filling the vehicle tank. Thus, controller  110  may monitor the progress of the filling of the vehicle tank and when the pressure reaches a first pressure level corresponding to the low pressure level supplied from first supply line  212  (i.e., 2000 psi), controller  110  may close first low pressure fill valve  238   a  and open first medium pressure valve  240   a  while keeping closed first high pressure valve  242   a  such that CNG from the medium pressure bank supplied via second supply line  214  is dispensed to the vehicle tank. Then, when the pressure reaches a second pressure level corresponding to the medium pressure level supplied from second supply line  214  (i.e., 3000 psi), controller  110  may close first medium pressure fill valve  240   a . If the pressure selected by the user is 3000 psi, the sale is completed. On the other hand, if the pressure selected by the user is 3600 psi, controller  110  opens first high pressure valve  242   a  while keeping closed first low pressure valve  238   a  and first medium pressure valve  240   a  such that CNG from the high pressure bank supplied via third supply line  216  is dispensed to the vehicle tank. Once the pressure reaches a third pressure level corresponding to the user-selected pressure, controller  110  closes first high pressure valve  242   a  and completes the sale. 
     It will be apparent to those skilled in the art that the second branches with associated fill valves  238   b ,  240   b , and  242   b  that are used to feed second fill line  234   b  and fill hose  230   b  may be operated in the same manner. 
     A digital temperature sensor  270  ( FIG. 2 ) reads the ambient temperature of the outside air surrounding dispenser  205  and supplies the temperature data to controller  110 . Controller  110  may use the ambient temperature reading to adjust the pressure to which the vehicle tank is to be filled. For example, if the proper pressure for a vehicle is 3600 psi at 60° F., controller  110  reduces the pressure at colder temperatures such that the CNG does not over-pressurize as it warms up. Likewise, controller  110  increases the pressure at warmer temperatures. Controller  110  may display the ambient temperature on ambient temperature display  120 . 
     As noted above, the system further includes vent line  252  ( FIG. 1 ), which connects to vent hoses  250   a  and  250   b  extending from respective nozzles  232   a  and  232   b  via check valves  254   a  and  254   b.    
     Dispenser  205  further includes a pressure relief valve  256 , which is coupled to pressure relief lines  235   a  and  235   b  branching off of fill lines  234   a  and  234   b , respectively. Pressure relief valve  256  may open and vent to vent line  252  when the pressure in either of pressure relief lines  235   a  and  235   b  exceeds a predetermined pressure of, for example, 4500 psi. Pressure relief lines  235   a  and  235   b  may include check valves  258   a  and  258   b , respectively. A manually operated bleed valve  260  may be connected between pressure relief lines  235   a  and  235   b  and vent line  252  to bleed off excess pressure in fill lines  234   a  and  234   b  to vent line  252 . 
     Dispenser  205  may further include analog pressure gauges  248   a  and  248   b  for displaying pressure in fill lines  234   a  and  234   b , respectively. Such gauges  248   a ,  248   b  provide a way to confirm the accuracy and calibration of the digital pressure sensors  246   a  and  246   b.    
     Having generally described the basic structure of the LNG flow control components  210   a  of dispenser  205 , reference is made to  FIG. 2 , which shows the electronic components  207  of dispenser  205 . 
     As already mentioned, dispenser  205  includes dispenser controller  110 ; meters  244   a  and  244   b ; temperature sensor  270 ; pressure sensors  246   a  and  246   b ; fill valves  238   a ,  240   a ,  242   a ,  238   b ,  240   b , and  242   b ; and optional actuator valves  239   a ,  241   a ,  243   a ,  239   b ,  241   b , and  243   b . Dispenser controller  110  may comprise one or more of: microprocessors or equivalents thereof, programmed logic arrays, digital-to-analog converters, analog-to-digital converters, clocks, memory, buffers, and any other analog or digital circuitry to perform the functions described herein. 
     Dispenser  205  further includes a communication interface  112  that enables controller  110  to send and receive communications to and from a control console  200  that may control the pressure banks of a natural gas farm. According to one embodiment, the communication interface  112  and control console  200  may be coupled to one another through a network and communicate with one another using a PLC communication protocol. An example of a preferred protocol is disclosed in U.S. Provisional Application No. 61/793,256, entitled “IMPROVED FUEL DISPENSERS” filed on Mar. 15, 2013 by Sarah Ann Lambrix et al., the entire disclosure of which is incorporated herein by reference. 
     As also shown in  FIGS. 3 and 4 , dispenser  205  may further include the aforementioned fill hoses  230   a  and  230   b , fill nozzles  232   a  and  232   b , and a user interface section  265  including a user interface keyboard or numeric keypad  114 , user interface buttons  116 , a dispenser display  118 , an ambient temperature display  120 , a pressure display  122 , a sale/GGE display  124 , one or more grade selection displays  126 , one or more optional grade selection buttons  128 , a receipt printer  130 , a card reader  132 , and a stop button  134 . User interface buttons  116  are preferably capacitive touch switches to reduce the risk of a spark. Buttons  116  and dispenser display  118  are multifunctional. A duplicate user interface section  265  may be provided on the other side of dispenser  205  for use by a user operating fill hose  230   b.    
     Controller  110  may control display  118  to show graphic displays. One such graphic display is a fill indicator bar, which displays the relative levels at which the vehicle tank is filled based upon the sensed pressure relative to the desired pressure.  FIG. 5  shows an example of such a graphic fill indicator display  300 . The graphic fill indicator display  300  includes a graphic representation of a vehicle CNG tank  302  and may include a textual message  304 . When a fill is in progress, the tank graphic  302  is initially all colored white representing an empty tank. The textual message  304  may read “Fill in Progress.” As the vehicle tank fills, the tank graphic  302  shown on display  118  gradually changes in color from white to blue from the bottom of the tank upward to an extent proportional to the amount the vehicle tank is filled. For example, when the vehicle tank is half filled (as determined by the pressure of the tank relative to the selected pressure), tank graphic  302  is colored such that the bottom half is blue. When the vehicle tank is full, the tank graphic  302  turns all green and the textual message  304  reads “Full Fill.” 
     In addition, display  118  may be used to display graphic training illustrations such as those disclosed in U.S. Provisional Application No. 61/793,256, entitled “IMPROVED FUEL DISPENSERS” filed on Mar. 15, 2013 by Sarah Ann Lambrix et al., the entire disclosure of which is incorporated herein by reference. 
     Pressure display  122  is provided to display the pressure of the CNG fuel as sensed by a corresponding pressure sensor  246   a  or  246   b.    
     Sale/GGE display  124  is provided to display the sale cost (in dollars) and the gasoline gallon equivalent (GGE) or mass in pounds or kilograms of the CNG dispensed to the vehicle tank as measured by a corresponding meter  244   a  or  244   b . The GGE information may be displayed on an alternative existing display of dispenser such as displays  118 ,  120 , 122 , and  126  or on an additional display. Stop button  134  is provided for initiating an emergency stop. 
     Dispenser  205  may further include an optional gas sensor  138 , a boot nozzle sensor  140 , and a fresh air purge system  142 . 
     Gas sensor  138  is provided for sensing methane gas in the environment outside the dispenser cabinet. If gas is sensed, controller  110  performs a shutdown procedure at least until such time that gas is no longer sensed. This is an improvement over prior systems where a gas sensor was coupled to a remote controller that would shut down the dispenser in a less than orderly manner. 
     Boot nozzle sensor  140  senses when the nozzle  232   a ,  232   b  is inserted in a nozzle boot  274  and provides this information to controller  110 . In essence, boot nozzle sensor  140  serves as an on/off switch. Nozzle boot  274  may also include a locking mechanism for locking nozzle  232   a  or  232   b  in nozzle boot  274  when the dispenser is not operational. 
     Fresh air purge system  142  is provided in the upper chamber of the dispenser cabinet where the electrical components  207  are located to purge the air in this chamber with fresh air. This maintains a positive pressure in the electrical chamber, which keeps any methane gas from reaching the electrical components. 
     Components  210   b  of a second embodiment of a CNG dispenser are shown in  FIG. 6 , which is designed for a one-pressure bank system where a vent line  252  and only a high pressure supply line  216  are provided. In this embodiment, some of the components are eliminated and the remaining components are the same as those mentioned above. In essence, the second embodiment eliminates supply lines  212  and  214 , main shut off valves  218  and  220 , filters  224  and  226 , fill valves  238   a ,  238   b ,  240   a , and  240   b , and manifolds  236   a  and  236   b.    
     In operation, controller  110  simply fills from a high pressure supply line (i.e., 4000 psi) by opening valve  242   a  or  242   b  depending on which fill hose  230   a  or  230   b  is being used, and keeping the valve open while monitoring the pressure reading from the corresponding pressure sensor  246   a  or  246   b  until the selected pressure is reached at which point controller  110  closes valve  242   a  or  242   b  and completes the sale. 
     Although the second embodiment does not provide the advantage of being capable of being used with a three-bank system, it still provides all of the other novel features and thus benefits from their advantages. 
     Although both of the above embodiments above show dispensers with two fill hoses, the various aspects of the present invention may be implemented in dispensers having one fill hose or dispensers having more than two fill hoses. Examples of two embodiments having four fill hoses (two per side) are shown in  FIGS. 7 and 8  and described further below. 
     In the embodiment shown in  FIG. 7 , all of the components are identical to the embodiment shown in  FIG. 1  except that the components  210   c  of the embodiment shown in  FIG. 7  include the following additional components: a third fill hose  230   c , a third nozzle  232   c , a third vent hose  250   c , a third check valve  254   c , a fourth fill hose  230   d , a fourth nozzle  232   d , a fourth vent hose  250   d , a fourth check valve  254   d , first, second, third, and fourth pressure relief valves  256   a ,  256   b ,  256   c , and  256   d , and first, second, third, and fourth hose selection valves  261   a ,  261   b ,  261   c , and  261   d . First and third pressure relief valves  256   a  and  256   c  may be configured to vent at about 3750 psi, whereas second and fourth pressure relief valves  256   b  and  256   d  may be configured to vent at about 4000 psi. 
     In the embodiment shown in  FIG. 7 , the system operates similar to the embodiment of  FIG. 1  except that for each side of dispenser, a fill hose is provided for delivering CNG at 3000 psi (first and third fill hoses  230   a  and  230   c ) and a fill hose is provided for delivering CNG at 3600 psi (second and fourth fill hoses  230   b  and  230   d ). Accordingly, controller  110  controls hose selection valves  261   a  and  261   d  to open one of those valves and close the other valve depending upon the pressure selected by the user so that CNG is delivered to the appropriate one of fill hoses  230   a  and  230   d  corresponding to the selected pressure. Controller  110  similarly controls hose selection valves  261   b  and  261   c  to select to which fill hose  230   b  or  230   c  to deliver CNG associated with the user selected pressure. This allows different nozzles to be used for different pressures. 
     In the embodiment shown in  FIG. 8 , all of the components are identical to the embodiment shown in  FIG. 6  except that the components  210   d  of the embodiment shown in  FIG. 8  includes the following additional components: a third fill hose  230   c , a third nozzle  232   c , a third vent hose  250   c , a third check valve  254   c , a fourth fill hose  230   d , a fourth nozzle  232   d , a fourth vent hose  250   d , a fourth check valve  254   d , first, second, third, and fourth pressure relief valves  256   a ,  256   b ,  256   c , and  256   d , and first, second, third, and fourth hose selection valves  261   a ,  261   b ,  261   c , and  261   d . First and third pressure relief valves  256   a  and  256   c  may be configured to vent at about 3750 psi, whereas second and fourth pressure relief valves  256   b  and  256   d  may be configured to vent at about 4000 psi. 
     In the embodiment shown in  FIG. 8 , the system operates similar to the embodiment of  FIG. 6  except that for each side of dispenser  205 , a fill hose is provided for delivering CNG at 3000 psi (first and third fill hoses  230   a  and  230   c ) and a fill hose is provided for delivering CNG at 3600 psi (second and fourth fill hoses  230   b  and  230   d ). Accordingly, controller  110  controls hose selection valves  261   a  and  261   d  to open one of those valves and close the other valve depending upon the pressure selected by the user so that CNG is delivered to the appropriate one of fill hoses  230   a  and  230   d  corresponding to the selected pressure. Controller  110  similarly controls hose selection valves  261   b  and  261   c  to select to which fill hose  230   b  or  230   c  to deliver CNG associated with the user selected pressure. This allows different nozzles to be used for different pressures. 
     The above description is considered that of the preferred embodiments only. Modifications of the invention will occur to those skilled in the art and to those who make or use the invention. Therefore, it is understood that the embodiments shown in the drawings and described above are merely for illustrative purposes and not intended to limit the scope of the invention, which is defined by the claims as interpreted according to the principles of patent law, including the doctrine of equivalents.