Patent Publication Number: US-2019178267-A1

Title: Assembly for filling a gas tank

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority of German patent application no. 10 2017 011 344.0, filed Dec. 8, 2017, the entire content of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to an assembly for filling a gas tank for a gas-powered combustion engine. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 8,807,240 B2 has disclosed a handheld work apparatus which, as an operating fluid tank, has an exchangeable gas cartridge. The gas cartridge is provided for being inserted upside down into a receptacle on the housing of the work apparatus. When the gas cartridge has been emptied, it must be exchanged for a new gas cartridge. For a relatively long period of working operation, the user must therefore keep a stock of a corresponding number of gas cartridges. Empty gas cartridges are recycled or are refilled at other locations with suitable filling plants. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an assembly for filling a gas tank for a gas-powered combustion engine, which assembly is easy to operate and permits rapid on-site refilling of a gas tank. 
     This object can, for example, be achieved via an assembly for filling a gas tank for a gas-powered combustion engine. The assembly includes: a gas-filled storage bottle; the gas tank; a filling device arranged between the gas tank and the storage bottle; the gas tank having at least one fill valve, a pressure relief valve for gas in the gaseous state, and an extraction valve for liquefied gas; the filling device having a gas connection for the storage bottle and a fill connection for the fill valve; the fill valve being connected to the storage bottle via the filling device; wherein, when the fill valve is open, liquefied gas flows from the storage bottle into the gas tank via the fill valve and, during the inflow of liquefied gas, the pressure relief valve of the gas tank is configured to at least intermittently open; and, a filling level gauge configured to indicate a predefined filling level of the gas tank. 
     Between the gas tank for filling and a storage bottle, there is arranged a filling device which has a gas connection for the storage bottle and a fill connection for a fill valve of the gas tank. The gas tank has not only the fill valve for liquefied gas but also a pressure relief valve for gas in the gaseous state and an extraction valve for liquefied gas. The fill connection of the filling device is connected to the fill valve of the gas tank. During the inflow of liquefied gas through the fill valve into the gas tank, the pressure relief valve of the gas tank is at least intermittently kept open. The storage bottle is situated geodetically higher than the gas tank, such that the liquefied gas can flow unpressurized from the storage bottle into the gas tank. Via the pressure relief valve, the empty area of the gas tank is kept at a low pressure level, such that the liquefied gas flows in without disruption. A predefined filling level of the gas tank is indicated via a filling level gauge, such that, when the predefined filling level is reached, the user can close the bottle valve and end the filling process. 
     In an embodiment, the filling level gauge is in the form of a float which, when the predefined filling level in the gas tank is reached, closes at least the fill valve. The fill process thus ends automatically without the need for the user to intervene. It is expedient if, when the predefined filling level is reached, the float closes not only the fill valve but also the pressure relief valve. 
     A simple embodiment of a filling level gauge is formed by a monitoring pipe. That opening of the monitoring pipe which is situated in the tank lies at the height of the predefined maximum filling level. When the latter has been reached, liquefied gas phase enters the monitoring pipe and flows out. The user thus recognizes that the predefined maximum filling level has been reached, and can close the bottle valve. 
     To identify the attainment of a predefined filling level regardless of position, provision is made for the filling level gauge to be in the form of a monitoring snorkel which floats on the liquid phase of the gas introduced into the tank. In the gas tank, there is provided a filling cage, the cage volume of which is smaller than the predefined filling volume of the gas tank. The monitoring snorkel is situated within the filling cage, which is permeable to liquid. If the filling level in the gas tank rises, the monitoring snorkel floats on the liquid level until it abuts against the filling cage. The monitoring snorkel remains positionally fixed, while the filling level rises further. The monitoring snorkel is thus submerged by the liquid phase of the gas, such that liquefied gas emerges via the monitoring snorkel. Owing to the emergence of liquefied gas phase, the user can recognize that the predefined filling level has been reached, and can close the bottle valve. 
     In an embodiment, the filling cage is arranged in the gas tank with a distance on all sides. Here, the filling cage is configured such that, irrespective of the situation of the gas tank, the monitoring snorkel is always submerged by liquefied gas phase when the predefined maximum filling level has been reached. It is thus ensured that—irrespective of the situation of the gas tank during the filling process—a residual volume of the gas tank remains free from liquefied gas phase. 
     The monitoring pipe or the monitoring snorkel is expediently connected to the pressure relief valve of the gas tank. In an embodiment, provision is made for the pressure relief valve to be connected to a pressure reducer, which reduces the pressure of the outflowing gas in the gaseous state. 
     In an embodiment, provision is made for the filling device to be formed with a pump. The pump is in particular in the form of a membrane pump. To ensure unpressurized pumping, provision is made for the pressure connection of the pump and the suction connection of the pump to be connected to one another via a pressure equalization valve. Unpressurized conveyance of liquefied gas is thus achieved. 
     In an embodiment, the pump is equipped with a magnetically driven pump element, at least one drive magnet of the pump element being arranged outside the closed pump housing. The pump housing thus has no passages, which have to be sealed, for moving parts. 
     The drive magnet is situated in a drive plane and is provided for being moved relative to the pump element by a movement drive. The attracting or repelling magnetic forces move the pump element up and down as soon as the drive magnet is moved in the drive plane by the movement drive. To realize good conveying performance, provision is made whereby, above the pump element, multiple drive magnets are arranged on a circular path. A large stroke is achieved if the multiple drive magnets have alternating polarity. The drive magnets which follow one another on a circular path preferably each have different polarity. 
     The gas tank is advantageously mounted on a gas-powered combustion engine and provided so as to enable the outlet of the pressure relief valve to open into an intake channel of the combustion engine. 
     The gas-powered combustion engine is preferably provided as a drive engine in a handheld work apparatus, the fillable gas tank being fixedly mounted on the work apparatus as an operating fluid tank fixed to the apparatus. 
     Further advantageous embodiments are realized through any desired combination of the stated features and of the described embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will now be described with reference to the drawings wherein: 
         FIG. 1  shows, in a schematic side view, a handheld work apparatus with a gas tank, based on the example of a motorized chainsaw; 
         FIG. 2  shows, in a schematic side view, a handheld work apparatus with a gas tank, based on the example of a blower apparatus; 
         FIG. 3  shows a schematic partial view of the gas tank of a work apparatus as an operating fluid tank on a combustion engine; 
         FIG. 4  is a schematic illustration regarding the feed of liquefied gas to a mixture formation unit of a combustion engine; 
         FIG. 5  is a schematic illustration of an assembly for filling a gas tank; 
         FIG. 6  is a schematic illustration of a gas tank with a monitoring snorkel within a filling cage; 
         FIG. 7  is a schematic illustration as per  FIG. 6  with a gas tank in an altered situation; 
         FIG. 8  is an illustration as per  FIG. 6  with a gas tank in an altered situation; 
         FIG. 9  shows an assembly for filling a gas tank with a pump; 
         FIG. 10  is a diagrammatic illustration of a pump with a hand crank; and, 
         FIG. 11  shows a section through the pump as per  FIG. 10 . 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
       FIG. 1  shows a handheld work apparatus  1  based on the example of a motorized chainsaw. The work apparatus  1  has a housing  2  which has a rear handle  3  and an upper bale handle  4 . The bale handle extends from one longitudinal side of the housing  2  to the other longitudinal side of the motorized chainsaw. The handle  3  extends in a longitudinal direction of the work apparatus. A front guide bar  5  also extends in the longitudinal direction of the work apparatus, which guide bar is provided on the front end of the housing  2 . A saw chain  6  circulates on the guide bar  5 , which saw chain is driven, via a sprocket which is not illustrated, by a combustion engine  10  provided in the housing  2 . The combustion engine  10  is illustrated physically in  FIGS. 3 and 11 . Combustion engine  10  is operated with liquefied gas from a gas tank  11  provided in particular as an operating fluid tank  50 . In the embodiment as per  FIG. 1 , the gas tank  11  as operating fluid tank  50  is situated in the housing  2  of the work apparatus  1  below an air filter  7  in the region of the rear handle  3 . 
     The operation of the saw chain  6  is controlled by a safety brake device. An actuating bracket  8  which is arranged between the saw chain  6  and the upper bale handle  4  serves as an actuating element of the safety brake device. 
     The combustion engine  10  is started via a pull-rope starter  9 . A spring-type starter, an electrical starter or similar starting device may also be provided as starting device. 
       FIG. 2  illustrates a work apparatus  1  based on the example of a backpack-type blower apparatus. The combustion engine  10  is arranged in the housing  2  of the blower apparatus. The combustion engine  10  drives a blower impeller which is arranged in a blower housing  12 . The blower housing  12  opens into a blower tube  13 , which is provided for being operated via a handle  14 . 
     A spray fluid is fed via a line  15  to the blowing air stream emerging from the blowing tube  13 , which spray fluid is stored in a spray fluid tank  16 . 
     Below the combustion engine  10 , a gas tank  11  as operating fluid tank  50  is situated between the carrier frame  17  of the backpack-type blower apparatus and the housing  2  of the drive. Liquefied gas as operating fluid is fed from the gas tank  11  to the combustion engine  10 . 
     As shown in  FIGS. 3 and 4 , the gas-powered combustion engine  10  has a cylinder  18  with a combustion chamber  19 , which is delimited by a piston  20 . For the feed of combustion air  21 , an intake channel  31  is formed, expediently on a mixture formation unit  30 . A gas  23  is fed via a supply line  22  to the mixture formation unit  30 . The gas  23  is advantageously fed in the liquid phase. The supply line  22  in the gas tank  11  is preferably in the form of an elastic hose  28 , the end of which has an opening  24 . The liquefied gas  23  enters the supply line  22  from the gas tank  11  at the opening  24 . As shown for example in  FIG. 5 , the opening  24  is expediently formed as a suction housing  25 . A weight that is preferably provided at the opening  24  ensures that the opening  24  is situated in the liquefied phase of the stored gas  29  in every situation of the gas tank  11 . The elastic hose  28  extends from the opening  24  in the liquefied gas phase to a pass through  32  in the tank wall  33 . In the pass through  32 , there is preferably provided an extraction valve  34  which permits the extraction of the stored, liquefied gas  29  from the gas tank  11 . 
     As shown in  FIG. 3 , in the embodiment illustrated, the gas tank  11  is fixed to the crank case  40  of the combustion engine  10 . For this purpose, the crank case  40  expediently has at least one, preferably two, carrying clamps  41 ,  42 , which may in particular be formed integrally with the crank case  40 . The cylinder  18  is fixed to the crank case  40 , wherein, in the crank case  40 , there is mounted a crank shaft  43 , which is connected via a connecting rod  44  to the piston  20 . 
     As shown in  FIG. 4 , the combustion engine  10  is a piston-ported combustion engine, in particular a two-stroke engine. The intake  45 , connected to the mixture formation unit  30 , of the combustion engine  10  opens into the crank case  40 . The air/gas mixture entering the crank case  40  via the intake  45  is, as the piston  20  travels downward, compressed and forced via flow transfer channels into the combustion chamber  19  of the cylinder  18 . As the piston  20  travels upward, the mixture in the combustion chamber  19  is compressed and, in the region of the top dead center of the stroke movement, is ignited by an ignition device (not illustrated in any more detail). The combustion pressure drives the piston  20  downward again. Via an exhaust gas outlet  48 , the exhaust gases  61  are discharged via an exhaust muffler  64 . 
     As shown in  FIG. 4 , the liquefied gas  23  extracted from the gas tank  11  is fed in the arrow direction  60  to an evaporator  53 . For temperature equalization, the evaporator  53  is expediently situated in the spatial region of a heat source, for example in the spatial region of the cylinder  18 , of the exhaust muffler  64 , or is flowed around by the discharged exhaust gases  61 . The evaporator  53  ensures that the liquefied gas  23  fed in the arrow direction  60  in the liquefied phase transitions into the gaseous phase. Connected downstream of the evaporator  53  is a pressure reducer  54  for the gaseous phase of the gas. The outlet  55  of the pressure reducer  54  opens via a pressure-controlled control valve  56  into the control chamber  57  of a carburetor, in particular a membrane-type carburetor. The control chamber  57  is delimited by a flexible membrane  58 . If gas flows out of the control chamber  57  into the mixture formation unit  30 , the pressure in the control chamber  57  will decrease, and the membrane  58  will protrude into the control chamber  57 , as illustrated at the top left in  FIG. 4 . Via a lever assembly  59 , the membrane  58  opens the control valve  56 , such that gas  65  in the gaseous phase can flow from the pressure reducer  54  in the arrow direction  75  into the mixture formation unit  30 . 
     The gas tank illustrated in  FIG. 3  has not only the extraction valve  34  but also a fill valve  35  and expediently a pressure relief valve  36 , which is shown in  FIG. 5 . Arranged within the gas tank  11  is a protective cage  38  in which there is arranged an in particular mechanical filling level gauge  49 . The filling level gauge  49  is expediently configured as a float  39  which includes a hollow body  51  which floats on the liquid level of the filling level  37 . A predefined filling level  37  of the gas tank  11  can be indicated via the filling level gauge  49 . In an advantageous embodiment of the construction, provision is made whereby the float  39 , via a control lever  52 , controls at least the fill valve  35 . If the filling level  37  in the gas tank  11  reaches a predefined height, then at least the fill valve  35  is closed via the control lever  52 . It may be expedient if, alternatively to the fill valve  35  or simultaneously with the fill valve  35 , the pressure relief valve  36  is closed via the float  39 , as illustrated via dashed lines in  FIG. 5 . 
     The fill valve  35  and the pressure relief valve  36  open into the gas tank  11  within the protective cage  38 . The movable float  39  and its control lever  52  are likewise provided in the protective cage  38 . It is thereby ensured that the elastic hose  28 , which is movable in terms of its situation in the gas tank  11 , does not impair the mechanism of the filling level gauge  49 , or the float  39  thereof. The elastic, flexible hose  28  is situated permanently outside the protective cage  38 . 
     In a first embodiment of the assembly  66  for filling a gas tank  11 , provision is made for a storage bottle  70  to be connected via a filling device  80  to the gas tank  11 . The storage bottle  70  in this case lies higher, in terms of its situation, than the gas tank  11 . 
     The filling device  80  has a gas connection  81  for the storage bottle  70  and has a fill connection  82  for the fill valve  35 . The gas tank  11  is connected by the fill connection  82  and the fill valve  35  to the filling device  80 . Furthermore, a pressure relief valve  36  of the gas tank  11  is connected via a discharge connection  63 . The discharge connection  63  is connected—preferably via a pressure reducer  85 —to the atmosphere. 
     If the bottle valve  71  is connected to the gas connection of the filling device  80  and the bottle valve  71  is opened, then, owing to the higher situation of the storage bottle  70 , liquefied gas flows via the extraction hose  73  thereof via the bottle valve  71 , the gas connection  81 , the fill connection  82  and the fill valve  35  into the gas tank  11 , which is situated at a lower height. During the inflow of the liquefied gas  72  from the storage bottle into the gas tank  11 , the pressure relief valve  36  of the gas tank  11  is—at least intermittently—open. Via the discharge connection  63  of the filling device  80 , the pressure relief valve  36  is connected to the pressure reducer  85 . Gas—in the gaseous state—flowing out via the pressure relief valve  36  and the discharge connection  63  is released via the pressure reducer  85  into the surroundings. 
     To monitor the amount of liquefied gas  29  introduced into the gas tank  11 , a filling level gauge  49  is provided, which signals the present filling state  37  of the gas tank  11 . This may be realized visually or acoustically or recognized via the change in the phase of the outflowing gas. 
     As shown in  FIG. 5 , the filling level gauge  49  is in the form of a float  39  which, when a predefined filling level  37  is reached, closes at least the fill valve  35 . For this purpose, the float  39  is connected via a control lever  52  to the fill valve  35 . It may be expedient if, when the predefined filling level  37  is reached, the float  39  closes not only the fill valve  35  but also the pressure relief valve  36 . This is indicated by dashed lines in  FIG. 5 . 
     A simple embodiment of a filling level gauge is a monitoring pipe  95 , as illustrated in  FIG. 9 . In a predetermined situation of the gas tank  11 , the monitoring pipe  95  detects the predefined, in particular maximum admissible filling level  37 . When the filling level  37  is reached, liquefied gas phase will emerge from the monitoring pipe  95 , such that a user can recognize that the predefined filling level  37  has been reached. The gas expediently escapes from the monitoring pipe  95  via a pressure relief valve  36 . 
     It is preferable if the pressure relief valve  36  or the pressure reduction valve  85  in the embodiment as per  FIG. 5 or 9  opens into the atmosphere. It may be expedient for the outlet  26  of the pressure relief valve  36  or the pressure reduction valve  85  to open into the intake channel  31  of the combustion engine  10 . 
     In a preferred embodiment, the filling level gauge is in the form of a monitoring snorkel  90  as illustrated in  FIGS. 6 to 8 . The monitoring snorkel  90  floats on the liquid phase of the gas  29  introduced into the gas tank. The monitoring snorkel  90  is provided within a filling cage  91 , which is situated within the gas tank  11  with a distance  94  on all sides. The cage volume  92  of the filling cage  91  is smaller than a maximum filling volume  93  of the gas tank  11 . 
     If—for example in the tank situation in  FIG. 6 —the gas tank  11  is filled, the monitoring snorkel  90  will float on the liquid level  97  of the liquefied gas  29 . The filling cage  91  is permeable to the liquefied gas phase. The filling cage  91  is composed for example of a coarse-mesh, dimensionally stable network or grid. 
     If the liquid level  97  rises, the monitoring snorkel  90  abuts against the wall of the filling cage  91  and is submerged by the liquid level  97  of the liquefied gas phase, which rises further. Then, liquefied gas phase emerges via the monitoring snorkel  90  and indicates to the user that the tank has reached its predefined filling level  37 . 
     The advantage of the monitoring snorkel  90  consists in that it is connected—via an elastic hose—to the pressure relief valve and thus reliably indicates the attainment of the predefined filling level in every operating situation of the gas tank ( FIGS. 7 and 8 ). The contour of the filling cage  91  shown in  FIGS. 6 to 8  is selected such that, when the predefined filling level is reached, irrespective of the situation of the gas tank, a residual volume  98  of the gas tank  11  always remains free from liquefied gas phase. 
       FIG. 9  shows an assembly  66  for filling a gas tank  11 , having a filling device  80  in which a pump  88  is arranged. In the embodiment shown, the pump  88  is in the form of a membrane pump; other pump embodiments may be expedient. 
     The pump  88  of the filling device  80  as shown in the embodiment as per  FIG. 9  has a suction connection  83 , which is connected to the gas connection  81  for the supply bottle  70 , and a pressure connection  84 , which is connected to the fill connection  82  of the filling device  80 . Provision is made here for the pressure connection  84  of the pump  88  and the suction connection  83  of the pump  88  to be connected to one another via a pressure equalization valve  86 . In this way, unpressurized pumping of the liquefied gas phase is made possible. 
     The pump chamber  87  of the membrane pump is delimited by a membrane  89  which, driven by a movement drive  110 , performs pump strokes. The rear area  79 , which is separated from the pump chamber  87 , of the pump  88  is expediently connected via a connecting line  78  to the pressure connection  84  of the pump  88 . Higher conveying performance can be achieved in this way. 
     The pump  88  of the filling device  80  expediently has a magnetically driven pump element  101 , as shown in  FIG. 11 . For the movement of the pump element  101 , at least one drive magnet  103 ,  105 ,  107 ,  109  is arranged outside the closed pump housing  100 . In the embodiment shown, four drive magnets  103 ,  105 ,  107  and  109  lie in a drive plane  112  and are provided for being moved relative to the pump element  101  on a circular path  111  ( FIG. 10 ) about a rotary axis  102  via a movement drive  110 . It is preferable for drive magnets  103 ,  105 ,  107  and  109  which follow one another on the circular path  111  to have alternating polarity, such that, during a rotational movement about the rotary axis  102 , the pump element  101  is alternately attracted and repelled. In this way, the liquefied gas flowing in in the arrow direction  75  is sucked via a suction valve  104  into the pump chamber  87  and, via a pressure valve  106 , is fed via the pressure connection  84  of the pump housing  100  to the fill valve  35  in the arrow direction  77 . 
     The rotational movement of the movement drive  110  is, in the embodiment of  FIGS. 9 and 10 , actuated via a hand crank  108 . It may be expedient for the movement drive  110  to be provided by an attached battery-powered screwdriver, a drilling machine or the like. 
     It is understood that the foregoing description is that of the preferred embodiments of the invention and that various changes and modifications may be made thereto without departing from the spirit and scope of the invention as defined in the appended claims.