Patent Publication Number: US-2004045539-A1

Title: Gaseous fuel supply apparatus and with shut-off valve

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
     [0001] This is a Continuation Application of PCT Application No. PCT/JP02/04357, filed May 1, 2002, which was not published under PCT Article 21(2) in English. 
    
    
     
       [0002] This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2001-320263, filed Oct. 18, 2001, the entire contents of which are incorporated herein by reference.  
       BACKGROUND OF THE INVENTION  
       [0003] 1. Field of the Invention  
       [0004] The present invention relates to a gaseous fuel supply apparatus with a shut-off valve.  
       [0005] 2. Description of the Related Art  
       [0006] In recent years, from the viewpoint of environmental and energy resources problem, development of an automobile with an internal combustion engine using gaseous fuel instead of a diesel engine has been actively pursued. The automobile with the gaseous fuel engine has a plurality of gaseous fuel tanks in which gaseous fuel such as natural gas is stored under a high pressure. Gaseous fuel is fed from each of the gaseous fuel tanks to the gaseous fuel engine through a gaseous fuel supply apparatus. Each of the gaseous fuel supply apparatus has a gaseous fuel flow unit, for example, including a gas pipe extending from each of the gaseous fuel tanks toward the gaseous fuel engine. The plurality of gaseous fuel flow units extending from the plurality of gaseous fuel tanks are unified into one by an unification element such as a manifold, and one unified gaseous fuel flow unit reaches at the gaseous fuel engine.  
       [0007] Each of the gaseous fuel supply apparatus further has a shut-off valve provided in the gaseous fuel flow unit between the unification element and the gaseous fuel tank, and the shut-off valve selectively opens or shuts a flow of the gaseous fuel in the gaseous fuel flow unit. The conventional shut-off valve has a valve drive unit for driving a valve member by an electromagnetic force.  
       [0008] The conventional shut-off valve used in such a conventional gaseous fuel supply apparatus as described above is well known by Jpn. Pat. Appln. KOKAI Publication No. 10-141516. The shut-off valve disclosed in this publication comprises: a valve housing which includes a first connection port connected to a first part of a gaseous fuel flow unit, the first part being close to a gaseous fuel tank, a second connection port connected to a second part of the gaseous fuel flow unit, the second part being close to the gaseous fuel engine, and a valve chest provided between the first and second connection ports and having a valve port communicating the first and second connection ports with each other; a valve member which is provided in the valve housing and is movable between a closed position and an open position, at the closed position the valve member closing the valve port of the valve chest and at the open position the valve member separating from the valve port and opening the valve port of the valve chest; and a valve member drive unit which drives the valve member by an electromagnetic force.  
       [0009] In an inside surface of the valve chest of the valve housing, an area around the valve port is tapered to form a valve seat. A part of the valve member facing the valve seat is also tapered, and an O-ring is fit to a surface of the tapered part of the valve member.  
       [0010] In the conventional gaseous fuel supply apparatus, a gaseous fuel charge unit, for example, including a gas pipe, is branched from the unification element to charge gaseous fuel from an outer side into the gaseous fuel tank. A connection element for detachably connecting with an outer gaseous fuel source is provided on an extending end of the gaseous fuel charge unit. The gaseous fuel charge unit includes a switch valve at a position near to the connection element and a check valve at a position nearer to the unification element than the switch valve.  
       [0011] The gaseous fuel flow unit of the conventional gaseous fuel supply apparatus further has a by-pass unit with a check valve, which is for charging high-pressurized gaseous fuel into the gaseous fuel tank corresponding thereto. The by-pass unit connects a position between the unification element and the shut-off valve with a position between the shut-off valve and the gaseous fuel tank corresponding thereto in the gaseous fuel flow unit.  
       [0012] The gaseous fuel flow unit of the conventional gaseous fuel supply apparatus further has a check valve between the shut-off valve and the fuel tank sided bypass unit connection point. These by-pass unit and check valves are so structured that they prevent gaseous fuel from flowing through the shut-off valve while gaseous fuel is charged into the gaseous fuel tank from the outside.  
       [0013] In the conventional gaseous fuel supply apparatus as described above, the by-pass unit complicates the structure of the conventional gaseous fuel supply apparatus and increases the manufacturing cost of the conventional gaseous fuel supply apparatus.  
       [0014] If gaseous fuel charged from the outside to the gaseous fuel tank can be flown through the conventional shut-off valve for regulating a supply of gaseous fuel from the gaseous fuel tank to the gaseous fuel engine through the gaseous fuel flow unit, the conventional by-pass unit and the conventional check valves can be omitted so that the manufacturing cost of the conventional gaseous fuel supply apparatus can be decreased. However, if gaseous fuel charged from the outside into the gaseous fuel tank is flown through the conventional shut-off valve, the conventional shut-off valve tends to be failed.  
       [0015] The reason causing such a failure is as follows. The shut-off valve for the gaseous fuel flow unit drives the valve member relatively frequently by using electromagnetic force, and heat of high temperature generated by the electromagnetic force each time the valve member drive unit operates is transferred to the valve member. As a result, the heat of high temperature is also transferred to the O-ring on the valve member relatively frequently, and the O-ring is easily degraded by the heat. The degraded O-ring reduces the sealability of the shut-off valve.  
       [0016] Further, if the gaseous fuel charged from the outside into the gaseous fuel tank is flowed through the shut-off valve of the above described conventional gaseous fuel flow unit, the extremely highly pressurised gaseous fuel charged from the outside is expanded in an adiabatic condition and rapidly lowers the temperature thereof in the valve chest after the highly pressurised gaseous fuel passes through the valve port of the shut-off valve and flows into the valve chest. The gaseous fuel of such a low temperature is directly blown with high speed onto the O-ring on the valve member so that the O-ring on the valve member is rapidly chilled to lose the elasticity thereof. The elastically lowered O-ring tends to be broken into pieces and blown off from the valve member. And, this tendency becomes large with the progress of the degration of the O-ring by heat.  
       [0017] The present invention has been made under the above circumstances. It is an object of the present invention is to provide a gaseous fuel supply apparatus with a shut-off valve, which is simple in structure and is failed rarely.  
       BRIEF SUMMARY OF THE INVENTION  
       [0018] In order to achieve the above described object, a gaseous fuel supply apparatus with a shut-off valve according to one aspect of the present invention, comprises:  
       [0019] a gaseous fuel flow unit which is communicated with a gaseous fuel tank and a gaseous fuel combustion engine and flows gaseous fuel between the gaseous fuel tank and the gaseous fuel combustion engine;  
       [0020] a shut-off valve which is provided in the gaseous fuel flow unit and selectively opens or closes a flow of the gaseous fuel in the gaseous fuel flow unit; and  
       [0021] a gaseous fuel charge unit which is provided in the gaseous fuel flow unit between the gaseous fuel combustion engine and the shut-off valve and is used to charge the gaseous fuel from an outside into the gaseous fuel flow unit.  
       [0022] And, the shut-off valve comprises:  
       [0023] a valve housing which includes a first connection port connected to a first part of the gaseous fuel flow unit, the first part being close to the gaseous fuel tank, a second connection port connected to a second part of the gaseous fuel flow unit, the second part being close to the gaseous fuel engine and the gaseous fuel charge unit, and a valve chest provided between the first connection port and the second connection port and having a valve port communicating the first and second connection ports with each other;  
       [0024] a seal member which surrounds the valve port on an inner surface of the valve chest of the valve housing;  
       [0025] a valve member which is provided in the valve housing and is movable between a closed position and an open position, at the closed position the valve member being in contact with the seal member and closing the valve port of the valve chest and at the open position the valve member separating from the seal member and opening the valve port of the valve chest; and  
       [0026] a valve member drive unit which drives the valve member by an electromagnetic force.  
       [0027] Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter. 
     
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
     [0028] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention.  
     [0029]FIG. 1 is a schematic view of a gaseous fuel supply apparatus with a shut-off valve, according to an embodiment of the present invention;  
     [0030]FIG. 2 is an enlarged vertical sectional view of the shut-off valve of FIG. 1, with a valve member of the shut-off valve located at a closed position;  
     [0031]FIG. 3 is an enlarged exploded perspective view of the valve member and a plunger of a plunger-solenoid assembly, both being used in the shut-off valve of FIG. 2;  
     [0032]FIG. 4 is a vertical sectional view of the valve member of FIG. 3;  
     [0033]FIG. 5 is an enlarged vertical sectional view of one end portion of the plunger of FIG. 3;  
     [0034]FIG. 6 is a perspective view of an auxiliary seal member provided at the one end portion of the plunger of FIG. 5;  
     [0035]FIG. 7 is a vertical sectional view of a seal member supporting member which supports a seal member in a valve housing of FIG. 2;  
     [0036]FIG. 8 is a schematic vertical sectional view of the shut-off valve of FIG. 2, with the valve member of the shut-off valve being located at an open position; and  
     [0037]FIG. 9 is a schematic vertical sectional view of the shut-off valve of FIG. 2, with the valve member of the shut-off valve being in an initial state of moving from the closed position to the open position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0038] Hereinafter, a gaseous fuel supply apparatus with a shut-off valve, according to an embodiment of the present invention will be explained in detail with reference to the attached drawing.  
     [0039]FIG. 1 shows a schematic view of the gaseous fuel supply apparatus with the shut-off valve, according to the embodiment of the present invention.  
     [0040] The gaseous fuel supply apparatus  1  is used for supplying gaseous fuel from a gaseous fuel tank  2  storing gaseous fuel such as natural gas, to an internal combustion engine using gaseous fuel. The gaseous fuel supply apparatus  1  can be installed in structures, vehicles and ships, together with the gaseous fuel tank  2  and the internal combustion engine using gaseous fuel. The vehicles include a bus, truck and passenger car.  
     [0041] In this embodiment, the gaseous fuel supply apparatus  1  has two fuel tanks  2 ,  2 . Each of the two fuel tanks  2 ,  2  has one gaseous fuel inlet-outlet hole. A gaseous fuel flow unit  3  including a gas pipe is extended from the one gaseous fuel inlet-outlet hole. The extended ends of two gaseous fuel flow units  3  are unified into one unified gaseous fuel flow unit by an unification element  4  such as a manifold, and the one unified gaseous fuel flow unit is connected to the gaseous fuel internal combustion engine.  
     [0042] A normally opened fuel tank open/close valve  6  is provided at a position near to the one gaseous fuel inlet-outlet hole on each of the gaseous fuel flow units  3 , and further a shut-off valve  7  driven electromagnetically is provided at a position opposite to the one inlet-outlet hole with respect to the open/close valve  6  on each of the gaseous fuel flow units  3 . The electromagnetically driven shut-off valve  7  is so structured that it selectively opens or closes the flow of gaseous fuel in the gaseous fuel flow units  3 .  
     [0043] A gaseous fuel charge unit  8 , for example including a gas pipe, is also connected to the unification element  4 , and the charge unit  8  is used for charging high pressurized gaseous fuel from an outer gaseous fuel source (not shown) into the gaseous fuel tanks  2 . A connection element (not shown) for detachably connecting with the outer gaseous fuel source (not shown) is provided on the extended end of the charge unit  8 . The charge unit  8  includes a switch valve (not shown) at a position near to the connection element and a check valve (not shown) at a position nearer to the unification element than the switch valve.  
     [0044] Further, a pressure gauge (not shown) is provided on the unification element  4 , and the pressure gauge is used for measuring the pressure of gaseous fuel passing therethrough.  
     [0045] Next, the configuration of the electromagnetically driven shut-off valve  7  will be explained in detail with reference to FIGS.  2  to  7 .  
     [0046] Referring to FIG. 2, the shut-off valve  7  comprises a valve member drive unit  10  and a valve structure  11 .  
     [0047] The drive unit  10  includes an outer housing  15  and a plunger-solenoid assembly housed in the outer housing  15 . The plunger-solenoid assembly includes a rod-shaped core  16  and two types of solenoid coils  17 ,  18 . These coils  17 ,  18  are wound independently each other around the outer circumferential surface of the rod-shaped core  16  at two positions separated from each other along the longitudinal direction of the core  16 . A male screw is formed on the outer circumferential surface of one end portion  19  of the core  16 . The one end portion  19  of the core  16  is inserted into a through-hole formed in the outer housing  15 , directing from the inside space to the outside space of the outer housing  15 . A nut  20  is fixed to the outer projecting one end portion of the core  16 . With this structure, the core  16  with the solenoid coils  17 ,  18  is located at a predetermined position in the inside space of the outer housing  15 .  
     [0048] The first solenoid coil  17  located near to the one end portion  19  is configured to have a larger resistance than that of the second solenoid coil  18  located far from the one end portion  19 .  
     [0049] One end portion of a cylindrical movement guide member  15  is fixed to the outer circumferential surface of the other end portion of the core  16  by well known fixing means, for example, such as welding, so that the guide member  15  is coaxially arranged with the core  16 . A connection member  26  for connecting with the valve structure  11  is fixed to the outer circumferential surface of the other end portion of the guide member  25 . In this embodiment, a male screw is formed on the outer circumferential surface of the connection member  26 .  
     [0050] A columnar-shaped plunger  27  is arrange in the inside space of the guide member  25 , and the plunger  27  is slidable in the longitudinal direction of the guide member  25 . A tapered concave is formed in the end of the other end portion of the core  16 , and the end of the one end portion of the plunger  27  facing the end of the other end portion of the core  16  is tapered to correspond to the above-mentioned tapered concave. An urging element  28  is provided between the center of the concave on the end of the other end portion of the core  16  and the center of the end of the tapered one end portion of the plunger  27 . In this embodiment, the urging element  28  has a compression coil spring.  
     [0051] The valve structure  11  includes a valve housing  30 . The valve housing  30  is in contact with and fixed to a good thermal conductive member in an object in which the gaseous fuel supply apparatus  1  is installed. If the apparatus is installed in a vehicle, the good thermal conductive member is, for example, a chassis.  
     [0052] The valve housing  30  includes a valve chest  31 , a first connection port  32  connected to a first part of the gaseous fuel flow unit  3 , the first part being close to the gaseous fuel tank  2 , and a second connection port  33  connected to a second part of the gaseous fuel flow unit  3 , the second part being close to the internal combustion engine and unification element  4  (i.e., the gaseous fuel charge unit  8 ). The valve chest  31  is provided between the first connection port  32  and the second connection port  33 , and is communicated with the first connection port  32  through a communicating port  35 . The valve chest  31  is further communicated with the second communicating port  33  through a valve port  36 . Filters  37  and  38  are fixed in the first connection port  32  and second connection port  33 , and these filters  37  and  38  catch foreign matters included in the gaseous fuel passing through the first and second connection ports  32  and  33 . These filters  37  and  38  may be detachably fixed in the first and second connection ports  32  and  33 .  
     [0053] A valve member drive unit connection opening is formed at a position facing the valve port  36  in the inside surface of the valve chest  31 . The connection member  26  on the other end portion of the cylindrical movement guide member  25  of the valve drive unit  10  is fixed to the valve member drive unit connection opening, with a seal element  39  such as an O-ring.  
     [0054] A valve member  40  is provided between the valve port  36  and the other end portion of the plunger  27  of the valve member drive unit  10  in the valve chest  31  of the valve housing  30 .  
     [0055] As particularly shown in FIG. 3 in the enlarged fashion, a cylindrical blind hole  41  is formed in one end (the plunger facing end) of the valve member  40  which faces the other end portion of the plunger  27 , and the cylindrical blind hole  41  is arranged coaxially to the longitudinal center line of the plunger  27 . A pair of connection holes  42  are also formed in the valve member  40 , and the connection holes  42  are arranged on a line orthogonally extending to the longitudinal center line of the plunger  27 . The connection holes  42  penetrate the cylindrical blind hole  41  in the diametrical direction of the plunger  27 .  
     [0056] The other end portion of the plunger  27  is made as a small-diameter column  43 , and can be inserted into the cylindrical blind hole  41  of the valve member  40 . The small-diameter column  43  of the plunger  27  is slidable in the cylindrical blind hole  41  of the valve member  40  along the longitudinal direction of the plunger  27 . A connection hole  44  is formed in the small-diameter column  43 , and is extending in the diametrical direction of the plunger  27 . The diameter of the connection hole  44  in the small-diameter column  43  of the plunger  27  is smaller than the diameter of each of the connection holes  42  of the valve member  40 .  
     [0057] Before the valve member drive unit  10  is connected with the valve housing  30  as described above, the cylindrical blind hole  41  of the valve  40  is fitted on the small-diameter column  43  of the other end portion of the plunger  27 , and a connecting rod  45  is inserted into the connection hole  44  in the small-diameter column  43  of the plunger  27  through the connection holes  42  of the valve member  40 . As a result of this, the valve member  40  is connected to the other end portion of the plunger  27  by the connecting rod  45 , and the valve member  40 , together with the other end portion of the plunger  27 , is movable. Further, the above-mentioned difference between the diameter of the connection hole  44  of the small-diameter column  43  of the plunger  27  and the diameter of each of the connection holes  42  of the valve member  40  causes the valve member  40  to be movable relative to the plunger  27  on the outer circumferential surface of the small-diameter column  43  of the plunger  27  along the longitudinal direction of the plunger  27  by the above-mentioned difference.  
     [0058] A communication port  50  is further formed in the valve member  40 . One end of the communication port  50  opens at the other end of the valve member  40 , and the other end of the communication port  50  opens at the one end of the valve member  40 , the other end facing the valve port  36  of the valve chest  31  of the valve housing  30  (that is, the valve port facing end) and the one end facing the plunger  27  (that is, the plunger facing end). More precisely, both ends of the communication port  50  open at a center of the bottom surface of the blind hole  41  on the one end (the plunger facing end) and at a center of the other end (the valve port facing end).  
     [0059] As particularly shown in FIG. 4 in the enlarged fashion, a circular projection  51  is provided around the opening of the communication port  50  at the bottom surface of the blind hole  41 , and the circular projection  51  swells up like a tapered shape around the above-mentioned opening.  
     [0060] As shown in FIGS. 2 and 3, an auxiliary seal member  52  is provided at the center portion of the end of the small-diameter column  43  of the plunger  27 . The auxiliary seal member  52  is made of synthetic rubber, for example.  
     [0061] As particularly shown in FIG. 5 in the enlarged fashion, au auxiliary seal member storing concave  55  is formed in the center portion of the end of the small-diameter column  43  of the plunger  27 . A diametrical size of the inner periphery of the storing concave  55  in the diametrical direction of the plunger  27  is larger than that of the opening of the storing concave  55  at the end of the plunger  27  in the diametrical direction. The auxiliary seal member  52  is stored in the storing concave  55 , and a circular stop washer  56  having the outer diameter larger than the diametrical size of the above-mentioned opening is also stored in the storing concave  55  between the above-mentioned opening and the auxiliary seal member  52 . The circular stop washer  56  prevents the auxiliary seal member  52  from escaping off from the storing concave  55  through the opening.  
     [0062] As particularly shown in FIG. 6, a plurality of radially extending grooves  57  is formed in a region of the outside surface of the auxiliary seal member  52 , the region facing the inside surface of the storing concave  55 . The plurality of grooves  57  configure a communicating structure for communicating the clearance between the inside surface of the storing concave  55  and the inside surface facing region of the outside surface of the auxiliary seal member  52 , with the clearance between the end of the other end portion of the plunger  27  (the end of the small-diameter column  43 ) and the plunger facing end of the valve member  40  (the bottom surface of the blind hole  41 ), through the opening of the storing concave  55 .  
     [0063] Now, referring back to FIG. 2, a circular seal member  61  is fixed to the circular part surrounding the valve port  36  on the inside surface of the valve chest  31  in the valve housing  30 . The seal member  61  is made of synthetic rubber, for example.  
     [0064] Explaining in more detail with reference to FIG. 7 in addition to FIG. 2, in this embodiment, a circular seal member support block  60  is fixed to the circular part surrounding the valve port  36  on the inside surface of the valve chest  31  in the valve housing  30 . The circular support block  60  is formed independently of the valve housing  30 . The circular support block  60  may be detachably fixed to the circular part on the inside surface of the valve chest  31 . A circular groove  62  is formed in a region of the outside surface of the circular support block  60 , the region facing the valve member  40 , and the circular groove  62  surrounds the valve port  36 . The circular seal member  61  is provided and fixed in the circular groove  62 . A center hole  60   a  of the circular support block  60  allows the communication between the valve chest  31  and second connection port  33  through the valve port  36 .  
     [0065] As shown in FIGS. 2 and 4, a circular projection  65 , projecting toward the circular seal member  61  around the valve port  36 , is formed at the other end (the valve port facing end) of the valve member  40 , the other end facing the valve port  36  of the valve chest  31 .  
     [0066] In the shut-off valve  7  structured as described above, the plunger  27  with the valve member  40  is normally urged, by the urging element  28 , toward the valve port  36  of the valve chest  31  in the valve housing  30 . Therefore, while electric current is not applied to the two solenoid coils  17  and  18  of the valve member drive unit  10 , the circular projection  65  at the other end (the valve port facing end) of the valve member  40  is pressed on the circular seal member  61  around the valve port  36  by the urging force of the urging element  28  applied to the valve member  40  through the plunger  27 , as shown in FIG. 2. Further, the auxiliary seal member  52  at the end of the other end portion of the plunger  27  (the end of the small-diameter column  43 ) is pressed on the projected end of the tapered projection  51  at the plunger facing end of the valve member  40  (the bottom of the blind hole  41 ) while the valve member  40  is arranged in the sealing position on the seal member  61 .  
     [0067] In this state, the shut-off valve  7  completely shuts off the communication through the valve chest  31  and valve port  36  between the first connection port  32  and second connection port  33  (i.e., between the gaseous fuel tank  2  and the gaseous fuel engine).  
     [0068] Now, the operation of the gaseous fuel supply apparatus with the shut-off valve, according to the embodiment of the present invention and configured as described above, will be described.  
     [0069] When charging gaseous fuel from the external gaseous fuel source (not shown) into one of the two gaseous fuel tanks  2 , the external gaseous fuel source (not shown) is connected with the connection element (not shown) at the extended end of the gaseous fuel charge unit  8  while electric current is not applied the two types of solenoid coils  17  and  18  of the shut-off valve  7  of each of the two gaseous fuel flow unit  3  and the shut-off valve  7  makes the valve member  40  arrange at the above described sealing position only by the urging force of the urging element  28 .  
     [0070] Then, the above described switch valve (not shown) in the gaseous fuel charge unit  8 , and gaseous fuel is charged from the external gaseous fuel source (not shown) through the gaseous fuel charge unit  8  and unification element  4  into the two gaseous fuel tanks  2 . The pressure of the charged gaseous fuel is very larger than that of gaseous fuel in the two gaseous fuel tanks  2 . Therefore, the high pressurized gaseous fuel flowing from the external gaseous fuel source (not shown) into the second connection port  33  of the shut-off valve  7 , pushes the valve member  40  together with the plunger  27  toward the core  16  against the pressure of the low pressurized gaseous fuel in the valve chest  31  communicating with the gaseous fuel tank  2  and the urging force of the urging element  28  of the valve member drive unit  10 .  
     [0071] As a result, as shown in FIG. 8, the valve member  40  separates from the seal member  61  around the valve port  36  in the valve chest  31 , and the high pressurized gaseous fuel flowing from the valve port  36  into the valve chest  31  is charged into the gaseous fuel tank  2  through the first connection port  35  and the remaining part of the gaseous fuel flow unit  3 . During this charging, the high pressurized gaseous fuel flowing through the shut-off valve  7  passes through the filters  38  and  37  provided in the second connection port  33  and first connection port  32 . If the high pressurized gaseous fuel contains foreign materials, the foreign materials are caught by the filters  38  and  27 , and the foreign materials do not flow into the gaseous fuel tank  2 .  
     [0072] The above-mentioned high pressurized gaseous fuel expands in the adiabatic condition and rapidly lowers the temperature thereof in the valve chest  31  just after the high pressurized gaseous fuel passes through the valve port  36  of the valve housing  30 . However, the gaseous fuel of low temperature just after passing through the valve port  36  is not directly blown on the seal member  61  around the valve port  36 . Therefore, the seal member  61  do not lose its elasticity greatly by the gaseous fuel of low temperature, and the seal member  61  is not drawn away from the groove  62  of the seal member support block  60  by the flow of the high pressurized gaseous fuel passing through the valve port  36  at high speed.  
     [0073] Further, the seal member support block  60  is made of material with a high thermal conductivity and high resistant to a change in temperature, the low temperature transferred from the high pressurized gaseous fuel of low temperature in the valve chest  31  to the seal member support block  60  can be rapidly diffused to the valve member housing  30  and the above-mentioned object with which the valve member housing  30  is in contact and in which the gaseous fuel supply apparatus  1  is installed. This causes the degree of loose of elasticity of the seal member  61  to be further lowered.  
     [0074] This filing is stopped when the above described pressure gauge (not shown) provided to the unification element  4  reaches a predetermined value. At this time, the above described switch valve (not shown) of the gaseous fuel charge unit  8  is closed, and then the outer gaseous fuel source (not shown) is separated from the connection element (not shown) at the extended end of the gaseous fuel charge unit  8 .  
     [0075] After the charging of the gaseous fuel is stopped as described above and the gaseous fuel does not flow through the valve port  36  of the valve housing  30 , the valve member  40  together with plunger  27  is pushed back toward the seal member  61  around the valve port  36  in the valve chest  31  in the valve housing  30  by the urging force of the urging element  28  of the valve member drive unit  10 . And, as shown in FIG. 2, the circular projection  65  at the end (the valve port facing end) of the other end portion of the valve member  40  is pressed on the circular seal member  61  around the valve port  36 , and the auxiliary seal member  52  at the end of the other end portion of the plunger  27  (the end of the small-diameter column  43 ) is pressed on the projected end of the tapered projection  51  of the plunger facing end (the bottom surface of the blind hole  41 ) of the valve member  40 .  
     [0076] In this state, the shut-off valve  7  completely shuts off the communication through the valve port  36  and valve chest  31  between the first connection port  32  and the second connection port  33  (i.e., between the gaseous fuel tank  2  and the gaseous fuel engine).  
     [0077] Further, the valve member  40  facing the valve port  36  directly is strongly urges to the closed position shown in FIG. 2, by the pressure difference between the gaseous fuel in the valve chest  31  communicating through the first connection port  32  with the gaseous fuel tank  2  in which the high pressurized gaseous fuel is charged, and the gaseous fuel in the second connection port  33  communicating with the gaseous fuel engine that is shut off the communication with the gaseous fuel tank  2  by the shut-off valve  7 .  
     [0078] In this state, the urging force coursed by the above described pressure difference is also applied to the plunger  27  which faces the valve port  36  indirectly through the communication hole  50  of the valve member  40 . However, since the cross sectional area of the communication hole  50  is very small relative to that of the valve port  36 , the urging force applied on the plunger  27  by the above described pressure difference is very small relative to the urging force applied on the valve member  40  by the above described pressure difference.  
     [0079] To drive the gaseous fuel engine by the gaseous fuel supplied from one of the gaseous fuel tanks  2 , at first a current with predetermined voltage is applied to the second solenoid coil  18  of low resistance of the valve member drive unit  10  in the shut-off valve  7  of each of the two gaseous fuel flow units  3  to generate a relatively large electromagnetic force.  
     [0080] The valve member  40  is freely movable relative to the plunger  27  by the above-mentioned difference (predetermine distance) between the diameter of each of the connection holes  42  of the valve member  40  and the diameter of the connection hole  44  of the small-diameter column  43  of the plunger  27 . Therefore, when the above-mentioned relatively large electromagnetic force is applied to the plunger  27 , the plunger  27  is easily moved by the above-mentioned predetermined distance in a direction in which the plunger  27  moves away from the valve port  36 , against the urging force of the urging element  28  and the small urging force caused by the above described pressure difference, while the valve member  40  is held at the closed position shown in FIG. 2 by the relatively large urging force caused by the above described pressure difference.  
     [0081] As a result, as shown in FIG. 9, the auxiliary seal member  52  at the end of the small-diameter column  43  of the plunger  27  is separated from the end of the tapered projection  51  at the bottom surface of the blind hole  41  in the plunger facing end of the outside surface of the valve member  40 .  
     [0082] The clearance between the end of the small-diameter column  43  of the plunger  27  and the bottom surface of the blind hole  41  in the plunger facing end of the outside surface of the valve member  40 , is communicated with the internal space in the valve chest  31  through the clearance between the outer circumferential surface of the column  43  and the inner circumferential surface of the blind hole  41  of the valve member  40 , the clearance between the connection rod  45  and each of the two connection ports  42  of the valve member  40 , and the clearance between the inner circumferential surface of the cylindrical movement guide member  25  and the outer circumferential surface of the valve member  40 . Therefore, a part of the high pressurized gaseous fuel in the valve chest  31  flows out from these clearances to the valve port  36  and the second connection port  33  through the communication hole  50  of the valve member  40 . And, the pressure difference between the gaseous fuel in the valve chest  31  and the gaseous fuel in the second connection port  33  is lowered, and the urging force caused by the pressure difference and urging the valve  40  toward the closed position is lowered.  
     [0083] That is, the unification of the auxiliary seal member  52  at the end of the small-diameter column  43  of the plunger  27  and the communication hole  50  of the valve member  40  functions selectively to lower the pressure difference.  
     [0084] At a moment when the auxiliary seal member  52  at the end of the small-diameter column  43  of the plunger  27  separates from the end of the tapered projection  51  at the bottom surface of the blind hole  41  in the plunger facing end of the outside surface of the valve member  40 , the high pressurized gaseous fuel rapidly flows from the above-mentioned clearance into the communication hole  50  of the valve member  40  so that the auxiliary seal member  52  is strongly drawn toward the communication hole  50 .  
     [0085] The auxiliary seal member  52  may be attached to the auxiliary seal member storing concave  55  in the end of the small-diameter column  43  of the plunger  27  by forcibly fitting the auxiliary seal member  52  in the storing concave  55 . However, in this case, a clearance is formed between the bottom surface of the storing concave  55  and the bottom surface facing end of the outer surface of the auxiliary seal member  52 . while the valve member  40  and the plunger  27  are located in the closed position, the high pressurized gaseous fuel in the valve chest  31  is flown into and stored in this clearance after the high pressurized gaseous fuel passes through the clearance between the end of the small-diameter column  43  of the plunger  27  and the bottom surface of the blind hole  41  in the plunger facing end of the outer surface of the valve member  40  and penetrates the auxiliary seal member  52 . The high pressurized gaseous fuel stored in the clearance on the bottom surface of the storing concave  55  serves to push out the auxiliary seal member  52  from the storing concave  55  when the auxiliary seal member  52  separates from the communication hole  50  and is strongly drawn toward the communication hole  50  as described above. If this phenomenon is repeated, the auxiliary seal member  52  may drop off from the end of the small-diameter column  43  of the plunger  27 .  
     [0086] However, in this embodiment, the communication structure configured by the plurality of grooves  57  formed in the inside surface facing region of the outside surface of the auxiliary sealing member  52  (refer to FIGS. 5 and 6) always surely communicates the clearance between the inside surface of the storing concave  55  and the inside surface facing region of the outside surface of the auxiliary sealing member  52  with the valve chest  31 . With this structure, although the high pressurized gaseous fuel from the valve chest  31  is stored in the clearance while the valve member  40  and the plunger  27  are located in the closed position, the high pressurized gaseous fuel stored in the clearance will not serve to push out the auxiliary sealing member  52  from the storing concave  55  while the auxiliary seal member  52  separates from the communication hole  50  and is strongly drawn toward the communication hole  50  as described above.  
     [0087] After the auxiliary seal member  52  on the small-diameter column  43  of the plunger  27  is separated from the communication hole  50  and the above described pressure difference strongly urging the valve member  40  toward the closed position is lowered as described above, the above described predetermined free movement of the plunger  27  relative to the valve member  40  is completed. Then, the plunger  27  further moves with carrying the valve member  40 , and can separates the valve member  40  easily from the closed position shown in FIG. 9.  
     [0088] After the valve member  40  is separated from the closed position shown in FIG. 9, electric current with the predetermined voltage is further applied to the first solenoid coil  17  of high resistance of the valve member drive unit  10 . And, the drive unit  10  can hold the plunger  27  together with the valve member  40  at the open position against the urging force of the urging element  28 , by the electromagnetic force generated in the first and second solenoid coils  17  and  18 . While the plunger  27  together with the valve member  40  is held at the open position as described above, the valve member  40  can be movable relative to the small-diameter column  43  of the other end portion of the plunger  27  in the above described predetermined distance. However, the valve member  40  is not arranged in the closed position while the valve member  40  moves in the above described predetermined distance.  
     [0089] The valve member drive unit  10  selectively uses the first or second solenoid coil  17  or  18  to move the valve member  40  from the closed position to the open position and then hold the valve member  40  in the open position. This makes the electric consumption which is need to operate the shut-off valve  7  according to the one embodiment of the present invention lower. Therefore, the plunger  27  and the valve member  40  are not heated heavily by the electromagnetic force generated for the above described operation, and the auxiliary seal member  52  provided on the end of the other end portion of the small-diameter column  43  of the plunger  27  is not influenced severely by the heat transferred from the plunger  27 . Further, the plurality of grooves  57  of the communication structure on the inside surface facing region of the outer side surface of the plunger  27  lowers the influence of the transferred heat from the plunger  27  to the auxiliary seal member  52 .  
     [0090] More further, the valve member  40  held in the open position is not in contact with the seal member  61  provided on the inside surface of the valve chest  31  and surrounding the valve port  36 . This causes the heat generated in the valve member drive unit  10  for moving the valve member  40  from the closed position to the open position and then holding the valve member  40  in the open position, not to be transferred to the seal member  61  through the plunger  27  and the valve member  40 . And, the seal member  61  is not influenced by the heat.  
     [0091] Even if the heat is transferred to the valve housing  30  of the valve structure  11  from the valve member drive unit  10  through the connection member  26 , the transferred heat is rapidly diffused to the above-mentioned object with which the valve housing  30  is in contact and to which the gaseous fuel supply apparatus  1  is provided. And, the seal member  61  is not degraded.  
     [0092] Further, since the seal member support block  60  holding the seal member  61  is formed independently of the valve housing  30 , it is possible to perform a process for making the seal member support block  60  hold the seal member  61  sufficiently and independently of the valve housing  30 . This process includes roughing (e.g., shot blasting) the inside surface of the groove  62  (refer to FIG. 7) to increase the strength of holding the seal member  61  in the circular groove  62 , applying adhesive in the groove  62 , injecting material of the seal member  61  into the groove  62  to hold the seal member  61  into the groove  62  and vulcanizing the injected material in the groove  62  to fix the seal member  61  in the circular groove  62 . It is important not to make a clearance between the inside surface of the groove  62 , the adhesive applied to the inside surface, and the seal member  61  injected into the inside surface, by the application of the adhesive, injection of seal member  61  and vulcanizing of the injected seal member  61 .  
     [0093] With this process, the holding strength of the seal member  61  in the seal member support block  60  can be extremely increased. Further, when replacing the seal member  61 , the seal member support block  60  holding the seal member  61  to be replaced can be removed from a predetermined region surrounding the valve port  36  in the inside surface of the valve chest  31  of the valve housing  30 , and then a new seal member support block  60  holding a new seal member  61  can be fixed to the predetermined region. Therefore, it is obvious that this detachably fixed seal member support block  60  makes the replacement of the seal member  61  being much faster and more secure, comparing with the case of fixing the seal member  61  directly to the predetermined region.  
     [0094] To stop supplying gaseous fuel from the two gaseous fuel tanks  2  to the gaseous fuel engine, apply of the electric current to the two solenoid coils  17  and  18  of valve member drive unit  10  is stopped.  
     [0095] As a result, the valve member  40  together with the plunger  27  is pushed back toward the seal member  61  around the valve port  36  in the valve chest  31  of the valve housing  30 , by the urging force of the urging element  28  of the valve member drive unit  10 . And, as shown in FIG. 2, the circular projection  65  at the other end (the valve port facing end) of the valve member  40  is pressed on the circular seal member  61  around the valve port  36 , and the auxiliary seal member  52  at the end of the other end portion of the plunger  27  (the end of the small-diameter column  43 ) is pressed on the projected end of the tapered projection  51  in the plunger facing end of the valve member  40  (the bottom surface of the blind hole  41 ).  
     [0096] In this state, the shut-off valve  7  completely shuts off the communication between the first connection port  32  and the second connection port  33  (i.e., between the gaseous fuel tank  2  and the gaseous fuel engine) through the valve port  36  and valve chest  31 .  
     [0097] Further, the valve member  40  is strongly urged to the closed position shown in FIG. 2, by the pressure difference between the gaseous fuel in the valve chest  31  communicating with the gaseous fuel tank  2  charged with the high pressurized gaseous fuel through the first connection port  32 , and the gaseous fuel in the second connection port  33  communicating with the gaseous fuel engine that is interrupted the communication with the gaseous fuel tank  2  by the shut-off valve  7 .  
     [0098] In one embodiment described above with reference to FIG. 2, gaseous fuel is supplied from the two gaseous fuel tanks  2 ,  2  to one gaseous fuel engine, or gaseous fuel is charged from an external gaseous fuel source into two gaseous fuel tanks  2 ,  2 . However, according to the aspect of the present invention, the gaseous fuel supply apparatus according to the present invention can be configured to supply gaseous fuel from one gaseous fuel tank to one or plural gaseous engines, and to supply gaseous fuel from two or more gaseous fuel tanks to one or multiple gaseous fuel engines.  
     [0099] Further, in the valve member drive unit  10 , if the material of auxiliary seal member can be held in the storing concave  55  at the end of the small-diameter column  43  of the plunger  27  without no clearance therebetween, such a no clearance held auxiliary seal member as described above can be used in place of the combination of the stop washer  56  and the auxiliary seal member  52  on the outside surface of which the plural grooves  57  are formed as shown in FIGS. 5 and 6. The no clearance held auxiliary seal member can be obtained by the same process as the above described process through which the seal member  61  is held in the circular groove  62  of the seal member holding block  60 . That is, the process includes roughing (e.g., shot blasting) the inside surface of the storing concave  55  to increase the strength of holding the no clearance held auxiliary seal member in the storing concave  55 , applying adhesive in the storing concave  55 , injecting material of the auxiliary seal member into the storing concave  55  and vulcanizing the injected material in the storing concave  55  to fix the auxiliary seal member in the storing concave  55 . It is important not to make a clearance between the inside surface of the storing concave  55 , the adhesive applied to the inside surface, and the auxiliary seal member injected into the inside surface, by the application of the adhesive, injection of auxiliary seal member and vulcanizing of the injected auxiliary seal member.  
     [0100] Further, if the positions of the two solenoid coils  17  and  18  in the valve member drive unit  10  are changed to each other, the valve member drive unit in which the positions of the two solenoid coils  17  and  18  are changed to each other as described above can perform the same operation as the valve member drive unit  10  in which the two solenoid coils  17  and  18  are positioned as shown in FIG. 2.  
     [0101] More further, the circular seal member  61  may be directly fixed to the circular part surrounding the valve port  36  on the inside surface of the valve chest  31  in the valve housing  30 , without using the circular seal member support block  60  formed independently of the valve housing  30 . In this case, a circular groove is formed in the circular part surrounding the valve port  36  on the inside surface of the valve chest  31  in the valve housing  30 , and the circular seal member  61  is provided and fixed in the circular groove  62 . The process for this provision and fixation may be the same as that for providing and fixing the material of the seal member  61  in the circular groove  62  formed on the above described seal member support block  60 .  
     [0102] More further, the gaseous fuel supply apparatus  1  according to one embodiment of the present invention and described above may be used to supply gaseous fuel to any kinds of gaseous fuel combustion engine other than the gaseous fuel internal combustion engine, including such as a gaseous fuel external combustion engine.  
     [0103] Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.