WO2003095883A1

WO2003095883A1 - Cryogenic fluid coupling

Info

Publication number: WO2003095883A1
Application number: PCT/US2003/014342
Authority: WO
Inventors: John Pickett; James Turey
Original assignee: J.C. Carter Japan K.K.
Priority date: 2002-05-07
Filing date: 2003-05-07
Publication date: 2003-11-20
Also published as: JP3389241B1; KR20040105548A; TWM269386U; CN1533489A; AU2003239380A1; JP2003322284A

Abstract

To provide a cryogenic fluid coupling (30) in which coalescence of male (10) and female coupling (20) is maintained even when the cryogenic fluid coupling is used alone while solving ice and gas purging problems, and which has satisfactory workability and a wide scope of application. The cryogenic fluid coupling is used to supply of cryogenic fluid between a storage tank and a mobile unit. A coalescing lock mechanism (8), which maintains or releases the coalescence of the male coupling member (10) and the female coupling member (20) in association with the coalescing linkage mechanism (1), is provided.

Description

CRYOGENIC FLUID COUPLING

Detailed Description of the Invention [Field of the Invention]

[0001 ] The present invention relates to a cryogenic fluid coupling for use in supplying cryogenic fluid, such as liquefied natural gas (LNG), between a storage tank and a tank of a mobile unit. [Prior Art]

[0002] Conventionally, cryogenic fluid, such as liquefied natural gas (LNG), is supplied, for example, from a storage tank provided at a base station to a tank of a mobile unit, such as a tank trailer, in the following manner. An open/close valve is provided on each of the base station and the mobile unit. The base station is provided with a loading arm on a supply pipeline extending from the open/close valve toward the mobile unit. The connection tip portion thereof has a flange structure. The connection flange can be moved vertically and horizontally and held at any position. The supply pipeline tip portion of the mobile unit also has a flange structure. The connection flange of the base station is aligned with the flange of the mobile unit and both flanges are joined together with a bolt, so that the supply pipelines of the base station and the mobile unit are connected to each other. Cryogenic fluid is supplied through the supply pipeline.

[0003] Note that when the cryogenic fluid is supplied, typically, the coupling of the base station and the mobile unit is performed in a closed system, in which not only the connection of the supply pipelines for supply but also connection of feedback pipelines, through which an amount of gas in the receiving tank equal to supplied cryogenic fluid is flowed back to the supplier tank, are required. The connection of the feedback pipelines has a structure similar to that of the supply pipelines.

[0004] The reason for such a simple structure of conventional pipeline connections will be descried below, where the cryogenic fluid is liquefied natural gas (LNG), for example. The liquefied natural gas has a temperature of as low as about -162°C in the liquid form. When a pipeline or the like accommodating it contact air, moisture in the air is immediately turned into ice which is in turn attached to the pipeline and interferes with a is not possible to employ a quick disconnect coupling commonly used for typical fluid, which has a valve mechanism at a connection tip portion thereof.

[0005] However, in the connection supply method, each pipeline is inevitably open to air from its open/close valve to the connection site. There is a risk of explosion caused by mixture of natural gas with oxygen contained in the air. Moreover- to avoid contamination of supply with foreign substances, after the base station and the mobile unit are connected with their flanges, gas purging is performed as follows. The air present in the pipelines between the open/close valves is first removed by forcedly injecting nitrogen gas. When only nitrogen gas is present in the pipeline, vaporized natural gas is forcedly injected therein, so that only vaporized natural gas occupies in the pipeline. Subsequently, both open/close valves are opened to allow liquefied natural gas to be supplied.

[0006] This gas purging is required when the connection of the pipelines is released after supply, and is performed in the reverse procedure.

[0007] In this case, when liquefied natural gas is supplied from the storage tank to the mobile unit (tank trailer), the supply efficiency is improved by providing a plurality of supply stations so as to supply a plurality of tank trailers. Since there is the possibility that gas purging causes leakage of vaporized natural gas, the startup of the engine of a tank trailer is forbidden during a time for which gas is supplied to other tank trailer, including the time of gas purging, i.e., liquefied natural gas must be simultaneously supplied to a plurality of tank trailers.

[0008] The gas purging also requires additional pipelines for discharging purged gas so as to discharge the same amount of inner gas as the forcedly-injected nitrogen gas or vaporized natural gas into the atmosphere. Therefore, unwanted gas must be discharged from a high chimney or the like located far away from the natural gas supply station. Further, minimization of such discharged gas is required in terms of environmental protection. [0009] U.S. Patent No. 5,429,155 proposes a cryogenic fluid coupling which provides a solution to the above-described problems with the supply of cryogenic fluid. This cryogenic fluid coupling is shown in Figure 19. [0010] A cryogenic fluid coupling comprises a female coupling provided in a mobile unit and a male coupling in a base station. A coalescing link mechanism provided in the male coupling is used to coalesce and fit the mail coupling with the female coupling, thereby making it possible to supply and flow cryogenic fluid between the male coupling and the female coupling.

[0011] The female coupling comprises a valve tube and a butt valve element. The butt valve element is housed in the valve tube in such a manner that the butt valve element can be slid back and forth. The butt valve element is closed by a sealing portion of the valve tube and is given a biasing force so as to maintain the sealing. The male coupling comprises an outer tube, a valve tube and a butt valve element. The valve tube is housed in the outer tube in such a manner that the valve tube can be slid back and forth. The valve tube is given a biasing force so that the valve tube is maintained at a predetermined retracted position relative to the outer tube. The butt valve element is housed in the valve tube in such a manner that the butt valve element can be slid back and forth. The butt valve element is closed by a sealing portion of the valve tube, and is given a biasing force so as to maintain the sealing.

[0012] In the thus-obtained cryogenic fluid coupling, the coalescing linkage mechanism is used to hold and fit the male coupling into the female coupling so that the tip of the valve tube of the female coupling abuts the inner collar of the outer tube of the male coupling. In this situation, when the coalescing linkage mechanism is subjected to an attachment operation using a lever in a direction indicated by the solid line arrow shown in Figure 19, only the valve tube is slid relative to the outer tube forward (the solid line direction shown in Figure 19) to be fitted into the valve tube of the female coupling. In this case, the tips of butt valve elements and of the respective female and male couplings and push each other. In this situation, only the valve tube is slid forward so that the butt valve elements and are retracted relative to the respective valve tubes. Therefore, the sealing by the sealing portions is released, so that cryogenic fluid can be supplied and flowed between the female coupling and the male coupling. [0013] In this case, a cryogenic seal provided at the outer tip portion of the valve tube of the male coupling secures fluid seal between the valve tubes of the respective female and male couplings, whereby flowing cryogenic fluid cannot leak.

[0014] In the above-described cryogenic fluid coupling, the fluid seal between the butt valve elements and the valve tubes of the female and male couplings is released when the butt valve elements push each other while the fluid seal between the valve tubes is maintained. In this case, the space between the valve tubes sealed and isolated from the outside is considerably small and limited. The air contained in this space need not be particularly removed. Therefore, gas purging which is otherwise conventionally required is unnecessary.

[0015] The front edge of the valve tube of the female coupling and the front edge of the outer tube of the male coupling valve tube scrape off an ice film, which is generated by the influence of the cryogenic fluid and attached on the surface of the other coupling, when both are fitted together. Further, the outer tube is provided with an ice escape window which allows the scraped ice to escape to the outside so that the ice film generated and attached by the influence of the cryogenic fluid is prevented from interfering with satisfactory connection of the couplings.

[0016] However, the cryogenic fluid coupling allows simultaneous connection both between the fluid supply pipelines and between the feedback pipelines for excess gas, and has a structure in which the two couplings are placed adjacent to each other and combined and can be removed from each other. A maintenance mechanism for maintaining the connection coalescence of the couplings is provided as a separate body (apart from the coupling) between the couplings.

[0017] Therefore, it is assumed that when cryogenic fluid is supplied, the supply pipeline and the feedback pipeline are independently located at absolutely different positions, or when the feedback pipeline is unnecessary. In this case, if an attempt is made to use the cryogenic fluid coupling alone, the absence of the above-described maintenance mechanism leads to a situation that the connection coalescence cannot be maintained. Therefore, improvements are unavoidable in ease of handling and wide-range applications of couplings.

[Problems to be Solved by the Invention]

[0018] The present invention is provided to solve the above-described problems. The object of the present invention is to provide a cryogenic fluid coupling in which the coalescence of male and female couplings can be maintained when the cryogenic fluid coupling is used alone, and in which ease of handling and wide-range applications can be achieved while solving the ice and gas purging problems.

[Means for Solving the Problems]

[0019] A cryogenic fluid coupling according to claim 1 for use in transporting cryogenic fluid, such as liquefied natural gas (LNG), between a storage tank and a mobile unit, wherein a male coupling comprising a coalescing linkage mechanism having a coalescing manipulation lever is coalesced with a female coupling so as to transport fluid, wherein the cryogenic fluid coupling comprises a coalescing lock maintaining mechanism; and when the male coupling and the female coupling are fitted together by insertion and the coalescing manipulation lever are operated, fitting means provided for the male coupling and the female coupling is actuated, thereby maintaining the coalescence of the male coupling and the female coupling. •

[0020] According to the cryogenic fluid coupling in which male and female couplings are coalesced so that fluid can be supplied, a coalescing lock maintaining mechanism for maintaining or releasing coalescence of male and female couplings in association with a coalescing linkage mechanism is integrated with the cryogenic fluid coupling comprising the coalescing linkage mechanism. Therefore, the cryogenic fluid coupling can be used alone while solving the ice and gas purging problems. The scope of application of the coupling is large. After connection and coalescence, a worker can release and leave the coupling unattended and do other related tasks, thereby making it possible to improve efficiency. [0021] A cryogenic fluid coupling according to claim 2 for use in transporting cryogenic fluid, such as liquefied natural gas (LNG), between a storage tank and a mobile unit, wherein a male coupling is coalesced with a female coupling so as to transport fluid, wherein the male coupling comprises a coalescing linkage mechanism having a first butt valve element provided with material flowing holes on a peripheral wall thereof, a valve tube provided with a material opening at a storage tank side and a valve port at a female coupling side, in which the valve port is closed by the first butt valve element consistently given a biasing force, an outer tube housing the valve tube, in which the valve tube is consistently given a biasing force in a non-coalescing direction, and a coalescing manipulation lever, wherein the coalescing manipulation lever is operated so that the valve tube is shifted relative to the outer tube to a coalescence position, the female coupling comprises a second butt valve element provided with a material flowing hole at a peripheral wall thereof, and a junction tube provided with a material opening at a mobile tank side thereof and a valve port at a male coupling side thereof, in which the valve port is closed by the second butt valve element consistently given a biasing force, the cryogenic fluid coupling further comprises a coalescing lock maintaining mechanism, wherein the coalescing lock maintaining mechanism comprises at least a latch claw pivoted at an appropriate position of an outer wall of the outer tube of the male coupling while being given a biasing force in a locking direction, a lock tube moved back and forth outside the outer tube in association with the valve tube, and a latch groove provided at a position of the junction tube of the female coupling corresponding to the latch claw, thereby, when the outer tube of the male coupling is fitted into the junction tube of the female coupling by insertion, the latch claw is locked by the latch groove; thereafter, when the coalescing manipulation lever is operated into a coalescing direction, the valve tube is shifted so that the first and second butt valve elements abut each other, whereby the valve ports of the valve tube of the male coupling and the junction tube of the female coupling are opened and cryogenic fluid is permitted to be transferred while the lock tube covers the latch claw so as to maintain disabling of release of the lock state. [0022] In the cryogenic fluid coupling, the structure of the coupling capable of supplying cryogenic fluid without being influenced by ice generated by cryogenic fluid is clarified, and the structure of the coalescing lock maintaining mechanism is also clarified in the structure of the coupling. Specifically, the coalescing lock maintaining mechanism has a simple configuration in which in the male coupling, a latch claw is provided in the outer tube and a lock tube is provided in such a manner that the lock tube is slid outside the outer tube in association with the coalescing linkage mechamsm, while in the female coupling, a latch groove is provided at the outer wall of the front edge of the junction tube. Thereby, the coalescing lock maintaining mechanism as a unit can be achieved without increasing the cost of the entire coupling much.

[0023] A cryogenic fluid coupling according to claim 3 is the cryogenic fluid coupling of claim 2, in which a releasing taper portion is provided at a back side and rear portion of the latch claw and at an inner wall of a front edge of the lock tube, and when the lock tube is positioned at a rear end, the releasing taper portions abut each other so that the latch claw is moved in a lock releasing direction.

[0024] In the cryogenic fluid coupling, lock/release can be achieved simply by providing a release taper portion on the lock tube and the latch claw. The lock/release is also carried out in association with the coalescing linkage mechanism. The configuration is simple and the cost is reduced.

[0025] A cryogenic fluid coupling according to claim 4 is the cryogenic fluid coupling of any of claim 2 or 3, in which the male coupling and the female coupling comprise ice removing means for scraping off ice generated by cryogenic fluid; and the ice removing means comprises at least a scraper ring comprising a front edge of the outer tube of the male couphng, an ice escape hole provided at an appropriate position of the outer tube, a scraper ring provided at a tip of the valve tube of the male coupling, and a scraper ring comprising a front edge of the junction tube of the female coupling.

[0026] A cryogenic fluid coupling according to claim 5 is the cryogenic fluid coupling of any of claims 2 to 4, in which the first butt valve element of the male coupling has a sealing portion abutting the female coupling and the second butt valve element of the female coupling has a sealing portion abutting the male coupling; and the sealing portions are exchangeable.

[0027] In the cryogenic fluid coupling, the seal portions of the first butt valve element and the second butt valve element are removable and exchangeable. Therefore, the seal portion, which is the most important portion and is most frequently contacted and removed when the coupling is used so that abrasion often occurs, is exchangeable. The coupling can be continuously used by exchanging such a portion without reducing sealing perforaiance, thereby making it possible to reduce cost.

Brief Description of the Drawings [0028] Figure 1 is a front view showing an appearance of a cryogenic fluid coupling according to the present invention.

[0029] Figure 2(a) is a perspective view showing an appearance of the coupling in

Figure 1 showing a pre-lock state

[0030] Figure 2(b) is a perspective view showing an appearance of the coupling in

Figure 1 showing a lock state.

[0031 ] Figure 3 is a front view showing a male coupling in Figure 1.

[0032] Figure 4 is a longitudinal section view, taken along XA-XA of the male coupling in Figure 3.

[0033] Figure 5(a) is a longitudinal section view of a valve tube and a first butt valve element constituting the male coupling in Figure 1. [0034] Figure 5(b) is a front view of Figure 5(a).

[0035] Figure 5(c) is a diagram for explaining an operation of the first butt valve element relative to the valve tube in Figure 5(a).

[0036] Figure 6(a) is a longitudinal section view of the first butt valve element of

Figure 5(a).

[0037] Figure 6(b) is a front view thereof.

[0038] Figure 6(c) is a perspective view of an appearance thereof.

[0039] Figure 7(a) is a diagram showing m detail a front portion of an outer tube in

Figure 1.

[0040] _^ Figure 7(b) is a longitudinal section view thereof. [0041] - Figure 7(c) is a diagram showing a rear portion thereof in detail. [0042] Figure 8(a) is a cross-sectional view, taken along XB-XB in Figure 5(b).

[0043] Figure 8(b) is a longitudinal section view, taken along XC-XC.

[0044] Figure 8c(c) is a front view.

[0045] Figure 9(a) is a front view of the latch claw in Figure 1.

[0046] Figure 9(b) is a cross-sectional view, taken along XD-XD in (a). [0047] Figure 10(a) is a front view of the lock tube in Figure 1.

[0048] Figure 10(b) is a cross-sectional view thereof, taken along XE-XE in (c).

[0049] • Figure 10(c) is a longitudinal section view thereof.

[0050] Figure 11(a) is a front view of a linkage fixing plate in Figure 1.

[0051] Figure 11 (b) is a side view thereof.

[0052] Figure 12(a) is a front view of a connecting plate in Figure 1.

[0053] Figure 12(b) is a side view thereof.

[0054] Figure 13 is a longitudinal section view of a female coupling in Figure 1.

[0055] Figure 14(a) is a front view of a second butt valve element in Figure 13.

[0056] Figure 14(b) is a longitudinal section view thereof.

[0057] Figure 14(c) is a diagram showing an appearance thereof.

[0058] Figure 15(a) is a front view of a housing in Figure 13.

[0059] Figure 15(b) is a longitudinal section view thereof.

[0060] Figure 16 is a diagram for explaining the principle of a coalescing linkage mechanism of the male coupling in Figure 1.

[0061] Figure 17(a) is a diagram for explaining a lock releasing state of the coupling in Figure 1.

[0062] Figure 17(b) is a diagram for explaining a lock maintaining state.

[0063] Figure 18 is a diagram showing an exemplary whole system for LNG supply using the cryogenic fluid coupling in Figure 1.

[0064] Figure 19 is a diagram showing a conventional cryogenic fluid coupling.

[Detailed Description of the Preferred Embodiments]

[0065] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0066] Figure 1 is a front view of the appearance of a cryogenic fluid coupling according to the present invention. [0067] A cryogenic fluid coupling 30 consists of a male coupling 10 provided in a storage tank, such as a tank in a base station or a tank in a liquefied natural gas (LNG) supply station, and a female coupling 20 provided in a tank of a mobile unit, such as a tank trailer or an LNG-driven vehicle. The cryogenic fluid coupling 30 is used to supply cryogenic fluid, such as LNG, between the storage tank and the mobile unit.

[0068] The male coupling 10 comprises a coalescing linkage mechanism 1. The coalescing linkage mechanism 1 comprises a coalescing manipulation lever Id. The coalescing manipulation lever Id is subjected to an attachment operation using the lever from a pre-lock maintaining state [0] indicated by a chain double-dashed line in the figure to a lock maintaining state [6] indicated by a solid line along the solid line arc with an arrow, whereby both couplings are coalesced without gas purging or the influence of an ice film caused by cryogenic fluid so that fluid can be supplied.

[0069] The cryogenic fluid coupling 30 further comprises a coalescing lock maintaining mechanism 8 which maintains or releases the coalescence of the male coupling 10 and the female coupling 20 in association with the coalescing linkage mechanism 1 (within the view of Figure 1, the coalescing lock maintaining mechanism 8 comprises a lock tube 2 'Which moves in a direction indicated by a line with an arrow from the state indicated by the chain double-dashed line to the state indicated by the solid line in association with the coalescing linkage mechamsm 1, and a latch claw 3 whose movement in a lock releasing direction is regulated by the lock tube 2, and the like).

[0070] The male coupling 10 comprises an outer tube 4 and a valve tube 5 in addition to the above-described coalescing linkage mechanism 1, the lock tube 2 and the latch claw 3. [0071] The coalescing linkage mechamsm 1 comprises a linkage -fixing plate la, a connecting plate lb, a linking plate lc, and the above-described coalescing manipulation lever Id. The linkage fixing plate la is fixed at a fixation point A of an outer rear edge portion of the outer tube 4. The linkage fixing plate la supports the coalescing manipulation lever Id so that the coalescing manipulation lever Id can be rotated about a pivot B. The connecting plate lb is fixed at a predetermined position exposed from a rear portion of the outer tube 4 of the valve tube 5. The connecting plate lb is provided with a linkage supporting point D for allowing the valve tube 5 to be slid relative to outer tube 4 in association with the rotational operation of the coalescing manipulation lever Id. The linking plate lc links the linkage supporting point C of the coalescing manipulation lever Id and the linkage supporting point D of the connecting plate lb.

[0072] The coalescing linkage mechanism 1 further comprises a connecting rod le for connecting and associating the connecting plate lb with the lock tube 2. The connecting rod le is also a functional portion of the above-described coalescing lock maintaining mechanism

8.

[0073] The lock tube 2, the latch claw 3 for locking the coalescence of the male coupling 10 and the female coupling 20, the outer tube 4, and the valve tube 5 will be described in detail below.

[0074] The female coupling 20 comprises a housing 12 provided with a junction tube

11 which is to be fitted and coalesced with the male coupling 10 as described below, and an auxiliary connection device 15 connected to a rear portion of the housing 12 for connecting a pipeline of the mobile unit.

[0075] In this structure, the cryogenic fluid coupling 30 comprises the coalescing lock maintaining mechanism 8. Therefore, the attachment operation using the lever (the solid line arc with an arrow in Figure 1) of the coalescing linkage mechanism 1 causes the coalescing lock maintaining mechanism 8 to be slid in the solid straight line with an arrow in association with the valve tube 5. As a result, the outer wall of the latch claw 3 is covered by the lock tube 2 so that the movement of the latch claw 3 in a lock releasing direction is prevented, i.e., the latch claw 3 is prevented from being opened outward, thereby exhibiting a lock maintenance function. The coalescent lock maintaining mechanism 8 does not have any influence on a mechanism provided inside the outer tube 4 for solving the ice and gas purging problems.

[0076] Therefore, according to the present invention, cryogenic fluid coupling can be used alone while solving the ice and gas purging problems, whereby the scope of application of the coupling is large and a worker does not have to hold and take care of the coupling after the connection and coalescence and can operate other related tasks, thereby improving efficiency.

[0077] Figure 2 is a perspective view of the appearance of the coupling shown in

Figure 1. Figure 1(a) shows a pre-lock state and Figure 1(b) shows a lock state. The same portions as those described above are referenced with the same reference numerals, and the overlapping description is omitted.

[0078] The pre-lock state shown in Figure 2(a) corresponds to the state indicated by the chain double-dashed line in Figure 1. The lock state shown in Figure 2(b) corresponds to the state indicated by the solid line shown in Figure 1. With this perspective view, the relationship between position at which the coalescing linkage mechanism 1, the lock tube 2, the latch claw 3, the outer tube 4 and the coalescing lock maintaining mechanism 8 of the male coupling 10 are installed can be well understood.

[0079] Referring to Figure 2, the structure of the above-described cryogenic fluid coupling 30 provided with the coalescing lock maintaining mechanism 8 will be described in detail below.

[0080] Figure 3 is a front view showing the male coupling shown in Figure 1. Figure

4 is a cross-sectional view of the male coupling, longitudinally taken along XA-XA shown in

Figure 3. Figure 3 shows the male coupling 10 viewed over the paper in which the female coupling 20 is removed from Figure 1, and the male coupling 10 is in a pre-lock maintaining state (the state indicated by the chain double-dashed line).

[0081] As can be seen from Figure 3 and 4, the coalescing manipulation lever Id of the coalescing linkage mechanism 1 comprises a pair of vertically symmetrical levers provided on each of the right and left side of the coalescing linkage mechanism 1. A gripper

Ida, which is a round bar, is provided between the upper and lower levers. The worker holds the male coupling 10 using the gripper Ida.

[0082] The lock tube 2 is fitted with the outer wall of the outer tube 4, and can be slid back and forth relative to the outer tube 4 (upward and downward in Figure 4). A connection ring 21 is provided at a rear portion of the lock tube 2 in such a manner that the connection ring 21 contacts the inner wall of the lock tube 2. The connection ring 21 is fixed with a screw 22 from the outer wall of the lock tube 2. The connection ring 21 is provided with a female thread along its longitudinal direction, with which the tip male thread of the connecting rod le is engaged. With this connecting rod le, the lock tube 2 is linked with the connecting plate lb fixed with the valve tube 5. As a result, the lock tube 2 can be slid back and forth in association with the valve tube 5.

[0083] Three latch claws. 3 are supported by supporting points 3a so as to be positioned at respective three latch embedding holes provided at a front portion of the outer wall of the outer tube 4 so .that the three latch claws 3 can be rotated from the inside to the outside of the outer tube 4. A spring 3b is provided between a rear portion of the latch claw 3 and a corresponding portion of the outer tube 4 so that the latch claw 3 is always given a biasing force in a direction (toward the inside of the outer tube 4) such that a front edge (upper portion in Figure 4) of the latch claw 3 maintains the coalescing lock with the female coupling 20.

[0084] The valve tube 5 is housed in the outer tube 4 in such a manner that the valve tube 5 can be slid back and forth. A spring 41 is provided between the valve tube 5 and the outer tube 4. The spring 41 gives a biasing force to the valve tube 5 so that the valve tube 5 is maintained at a rear slide position relative to the outer tube 4. When the coalescing manipulation lever Id is rotated from the pre-lock maintaining state [0] to the lock maintaining state [6], the valve tube 5 is slid forward from the pre-lock maintaining state [0] to the lock maintaining state [6] (indicated by the chained double-dashed line) against the biasing force as shown in Figure 4.

[0085] A stop ring 42 is fitted on the outer wall of the outer tube 4 and substantially at the middle of the outer tube 4 with respect to the longitudinal direction thereof. The stop ring 42 abuts the connection ring 21 fixed with the lock tube 2 so that the lock tube 2 is not slid backward relative to the outer tube 4 beyond the stop ring 42. As a result, the valve tube 5 is regulated so that the valve tube 5 is not slid backward relative to the outer tube 4 beyond the

[0086] The valve tube 5 is further provided with an auxiliary tube 51 and a spring 52.

The first butt valve element 6 is provided with a male poppet 7. These will be described in detail below with reference to Figures 5 and 6.

[0087] Figure 5(a) is a longitudinal section of the valve tube and the first butt valve element constituting the male coupling shown in Figure 1. Figure 5(b) is a front view of

Figure 5(a). Figure 5(c) is a diagram for explaining the operation of the first butt valve element relative to the valve tube shown in Figure 5(a).

[0088] The valve tube 5 is provided with a cryoresistive sealing means 5a, a scraper ring 5b and a stop ring 5c at an outer front edge thereof. When the valve tube 5 is fitted with the male coupling 10, the cryoresistive sealing means 5 a provides a fluid seal between the valve tube 5 and the inner wall of the junction tube 11 fitted therewith. The scraper ring 5b is provided immediately before the sealing means 5 a and plays a role in scraping of an ice film attached on the inner wall of the junction tube 11. The stop ring 5c fixes the sealing means

5a and the scraper ring 5b so that the sealing means 5a and the scraper ring 56 do not drop off the tip of the valve tube 5

[0089] The inner wall of the front edge is opened so as to form a valve port 5h through which fluid is passed. The valve port 5h is closed by the first butt valve element 6 so that fluid seal is maintained.

[0090] A semicircular groove 5e for fixing the connecting plate lb shown in Figure 1 is provided at a predetermined position of a rear portion of the outer wall of the valve tube 5.

Further, a tapering female thread 5 f for a pipeline for connecting the tip of a pipeline from the storage tank is provided at the inner wall of the rear edge of the valve tube 5. The opening of the rear edge is a material opening 5g.

[0091] The valve tube 5 houses the first butt valve element 6 which can be slid back and forth, and an auxiliary tube 51 fixed by the stop ring 5d at a rear position thereof. The valve tube 5 houses the spring 52 between the auxiliary tube 51 and the first butt valve .

16

element 6. The spring 52 gives a biasing force to the first butt valve element 6 in a forward sliding direction. The biasing force causes the first butt valve element 6 to consistently close the valve port 5h of the valve tube 5, so that fluid seal is maintained. In this case, a predetermined gap E is formed between the front edge of the auxiliary tube 51 and the rear edge of the first butt valve element 6.

[0092] When the first butt valve element 6 receives a downward sliding force against the biasing force, the first butt valve element 6 is retracted relative to the valve tube 5 to the extent that the gap E is removed as shown in Figure 5(c), whereby the above-described fluid seal is released.

[0093] Most portions of the first butt valve element 6 are smaller as compared to the internal diameter of the valve tube 5 to the extent that a predetermined size of space is' generated. The first butt valve element 6 abuts the inner wall of the valve tube 5 without any- gap at two protrusion portions 6a provided around front and rear portions thereof. A sliding' metal ring 61 is embedded in a groove in the outer wall of the protrusion 6a so that the first butt valve element 6 can be smoothly slid in the valve tube 5.

[0094] Since the valve tube 5 and the first butt valve element 6 can maintain the fluid seal, the male coupling 10 has a so-called auto-sealing function such that even when the male coupling 10 is separated from the female coupling 20, fluid does not leak from the male coupling 10.

[0095] Figure 6(a) is a longitudinal section view of the first butt valve element shown in Figure 5(a). Figure 6(b) is a front view thereof. Figure 6(c) is a perspective view of an appearance thereof.

[0096] In addition to those described above, the first butt valve element 6 comprises a poppet attachment portion 6b provided at a tip thereof. A male poppet 7 comprises a poppet body 7a provided with a protruding end 7aa at a tip thereof and a seal body 7b constituting a sealing portion for closing the valve port 5h of the valve tube 5. The male poppet 7 is attached with a screw 62 to the poppet attachment portion 6b so that the seal body 7b is interposed between the poppet body 7a and the poppet attachment portion 6b. [0097] The seal body 7b is a sealing portion which is most frequently subjected to attachment and removal when the coupling is used, so that abrasion often occurs therein. The seal body 7b is exchangeable. Therefore, the coupling can be continuously used by exchanging such a portion without reducing sealing performance, thereby making it possible to reduce cost.

[0098] Further, since the seal body is exposed to cryogenic fluid, it is desirable that the seal body has cryoresistance and excellent sealing performance. A preferable material for the seal body is a polytetrafluorethylene sheet. Since the seal body is removable and exchangeable, when a more preferable material is available, exchange of the previous material with the more preferable material can achieve more preferable abrasion resistance and seal performance.

[0099] A material flowing hole 6c is provided immediately after the poppet attachment portion 6b of the first butt valve element 6 so that fluid can be passed from the outer wall to the inner wall of the first butt valve element 6 with as large a cross-sectional area for passing fluid as possible.

[0100] Figure 7(a) is a diagram showing in detail a front portion of the outer tube shown in Figure 1. Figure 7(b) is a longitudinal section view thereof. Figure 7(c) is a diagram showing a rear portion thereof in detail. Figure 8(a) is a cross-sectional view thereof, taken along XB-XB in Figure 7(b). Figure 8(b) is a XC-XC longitudinal section view. Figure 8(c) is a front view thereof.

[0101] The outer tube 4 is in the form of a tube as a whole. As shown in Figures 7(a) and (b), thsr 'outer tube 4 is provided with three latch embedding holes 4a at a front portion thereof which penetrate from the outer wall to the inner wall thereof. The latch embedding hole 4a is provided with a latch claw pivoting hole 4aa which penetrates the wall of the embedding hole 4a along the circumference direction. A spring pin or the like is fitted into the pivoting hole 4aa by insertion. Thus, the pivot 3a of the latch claw 3 described in Figure 4 is constructed. Further, the front edge of the outer tube 4 functions as a scraper ring 49 which scrapes off an ice film from the outer wall of the junction tube 11 which the outer tube

4 contacts.

[0102] The embedding hole 4a is provided with a latch claw rear receiving portion

4ab at a rear portion thereof. The latch claw rear receiving portion 4ab is provided with a spring receiving hole 4ac into which the spring 3b (Figure 4) for giving a biasing force to a rear lower surface of the latch claw 3 is to be embedded.

[0103] The ice escape window 4b is provided in the outer wall of the outer tube 4 after the latch embedding hole 4a. Ice attached on the outer wall of the valve tube 5 which is slid forward in the outer tube 4 is scraped off by the scraper ring 11a which is the front edge of the junction tube 11 of the female coupling 20 (Figure 13). The scraped ice is discharged from the ice escape window 4b.

[0104] A ring groove 4c for fitting the stop ring 42 (Figure 4) into the outer wall of the outer tube 4 is provided at the middle of the ice escape window 4b in the longitudinal direction thereof.

[0105] A semicircular groove 4d for fixing the linkage fixing plate la of the coalescing linkage mechanism 1 is provided at the end portion of the outer wall of the outer tube 4.

[0106] The inner wall of the outer tube 4 is provided with partial protrusion portions

4e and 4f at front and rear portions thereof. The inner diameters of the protrusion portions 4e and 4f are determined so that the protrusion portions 4e and 4f fit the outer wall of the valve tube 5 without a gap. The valve tube 5 can be smoothly slid in the outer tube 4 back and forth. A rear portion of the rear protrusion portion 4f corresponds to a front portion of the spring 41 shown in Figure 4, and receives the biasing force between the outer tube 4 and the valve tube 5.

[0107] Figure 9(a) is a front view of the latch claw shown in Figure 1. Figure 9(b) is a cross-sectional view, taken along XD-XD shown in Figure 9(a).

[0108] The latch claw 3 is in the form of a rectangular parallelepiped. The latch claw

3 is provided with a pivot hole 3a penetrating a rear portion of a longitudinal surface thereof (corresponding to the supporting point 3 a in Figure 4) and a groove on the lower side thereof extending parallel to the pivot hole. The front wall of the groove forms a latch portion 3d.

The back side of latch claw 3 opposed to the lower side on which the latch portion 3d is provided is a flat portion 3e extending beyond the pivot hole 3a. A rear portion of the latch claw 3 following the flat portion 3e comprises a releasing taper portion 3 s and a flat portion

3f. The releasing taper portion 3s causes the latch claw 3 to move counterclockwise or in the lock releasing direction about the pivot hole 3 a when the lock tube 2 is retracted at the rear end to contact the latch claw 3 (Figure 9(b)).

[0109] A spring receiving hole 3c for receiving the spring 3b shown in Figure 4 is provided at the lower side and rear portion of the latch claw 3, more specifically, at the position opposed to the latch portion 3d with respect to the pivot hole 3a.

[0110] Figure 10(a) is a front view of the lock tube shown in Figure 1. Figure 10(b) is a cross-sectional view, taken along XE-XE in Figure 10(b). Figure 10(c) is a longitudinal section view thereof.

[0111] The lock tube 2 is in the form of a cylinder as a whole. The lock tube 2 is provided with six windows 2a penetrating from the outer wall to the inner wall thereof which are equally spaced along the circumference. The lock tube 2 has a protrusion portion 2b having a smaller inner diameter at a front portion (in the assembly) and a release taper portion

2s, which corresponding to the release taper portion 3s of the latch claw 3, after the protrusion portion 2b, i.e., the inner side of the front edge of the lock tube 2. The inner diameter of the lock tube 2 is increased toward the rear portion along the release taper portion

3s.

[0112] An attachment hole 2c for attaching the connection ring 21 shown in Figure 4 is provided around the rear edge of the lock tube 2.

[0113] As can also be seen from Figure 4, the protrusion portion 2b covers the outer wall of the latch claw 3 provided in the outer tube 4, playing a role in regulating the latch claw 3 so that the latch claw 3 does not enter the lock releasing state from the lock maintaining state. [0114] As can also be seen from Figure 4, the above-described release taper portions

3s and 2s of the respective latch claw 3 and lock tube 2 cause the latch claw 3 to move counterclockwise or in the lock releasing direction when the lock tube 2 is retracted at the rear end (slightly further downward from the situation shown in Figure 4) to contact the latch claw 3.

[0115] Figure 11(a) is a front view of the linkage fixing plate shown in Figure 1.

Figure 11 (b) is a side view thereof.

[0116] The linkage fixing plate la is in the form of a flat plate. The linkage fixing plate la is provided with a large-diameter outer tube fixing hole laa penetrating the upper and lower surface thereof, and an outer tube fixing auxiliary hole lab (corresponding to point

A in Figure 1) and a supporting point hole lac for fitting a pivot axis (supporting point B in

Figure 1) by insertion, both of which penetrate opposite sides of the linkage fixing plate la. .

[0117] Figure 12(a) is a front view of the connecting plate shown in Figure 1. Figure

12(b) is a side view thereof.

[0118] The connecting plate lb is in the form of a flat plate as a whole. The connection plate lb is provided with a large-diameter valve tube fixing hole lba penetrating the upper and lower sides thereof, a connecting rod hole lbb on the opposite sides thereof with respect to the longitudinal direction, through which the connecting rod le penetrates, and valve tube fixing auxiliary holes lbc penetrating sides thereof. The valve tube fixing auxiliary hole lbc corresponds to the linkage supporting pomt D in Figure 1.

[0119] Figure 13 is a longitudinal section view of the female coupling in Figure 1.

The longitudinal section view in Figure 13 shows the female coupling 20 (Figure 1) separated from the male coupling 10, and turned upside down.

[0120] As shown in Figure 13, the female coupling 20 comprises a second butt valve element 13 comprising a female poppet 14, and a spring 16 in addition to the junction tube

11, the housing 12 and the auxiliary connection device 15 described in Figure 1.

[0121] The junction tube 11 protrudes from the housing 12. The junction tube 11 and the housing 12 are assembled in such a manner that they can be separated. The junction tube 11 is fitted between the valve tube 5 and the outer tube 4 of the male coupling 10. The outer diameter of the fitting portion gradually decreases so as to fit into the male coupling 10. The junction tube 11 is provided with a scraper ring 1 la for scraping off an ice film attached on the male coupling 10, and a latch groove lib at a rear portion thereof, into which the latch portion 3d of the latch claw 3 provided in the outer tube 4 is fitted.

[0122] The inside of the junction tube 11 provides a passage for fluid. A side of the passage opposed to the male coupling is referred to as a material opening l ie. A portion of the junction tube 11 at which the passage is closed by the second butt valve element 13 so as to achieve fluid seal is referred to as a valve port l id.

[0123] Note that the latch groove 1 lb of the junction tube 11 , the latch claw 3 of the outer tube 4, the lock tube 2 for regulating the lock/release of the latch claw 3, and the like are fitting means for maintaining the connection of the male and female couplings. [0124] The scraper ring 1 la of the junction tube 11, the, scraper ring 5b of the valve tube 5, and the scraper ring 4g and the ice escape window 4b of the outer tube 4 are all means for removing ice. They are collectively referred to as ice removing means. [0125] , , The second butt valve element 13 is housed in the housing 12 in such a manner that the second butt valve element 13 can be slid back and forth. The second butt valve element 13 is consistently given a biasing force toward the junction tube 11 by the spring 16 so as to achieve fluid seal. As shown in Figure 13, the female coupling 20 has a so- called auto-sealing function such that even when the female coupling 20 is separated from the male coupling 10, fluid does not leak from the male coupling 20.

[0126] Figure 14(a) is a front view of the second butt valve element shown in Figure

13. Figure 14(b) is a longitudinal section view thereof. Figure 14(c) is an outline view thereof.

[0127] The second butt valve element 13 has substantially the same configuration as that of an upper portion of the first butt valve element 6 of the male coupling 10 in Figure 6. The second butt valve element 13 is provided with a poppet attachment portion 13a. A female poppet 14 comprises: a poppet body 14a comprising a protruding end 14aa provided at a tip of the poppet attachment portion 13a; and a seal body 14b forming a sealing portion with the junction tube 11. The female poppet 14 can be attached to the second butt valve element 13 with a screw 17 while the seal body 14b is interposed between the poppet body 14a and the poppet attachment portion 13a.

[0128] The seal body 14b is a sealing portion which is most frequently subjected to removal when the coupling is used, so that abrasion often occurs therein. The seal body 14b is exchangeable. Therefore, the coupling can be continuously used by exchanging such a portion without reducing sealing performance, thereby making it possible to reduce cost. [0129] Further, since the seal body is exposed to cryogenic fluid, it is desirable that the seal body has cryoresistance and excellent sealing performance. A preferable material for the seal body is a polytetrafluoroethylene sheet. Since the seal body is removable and exchangeable, when a more preferable material is available, exchange of the previous material with the more preferable material can achieve more preferable abrasion resistance and seal performance.

[0130] A material flowing hole 13b is provided immediately after the poppet attachment portion 13a of the second butt valve element 13 so that fluid can be passed from the outer wall to the inner wall of the second butt valve element 13 with as large a cross- sectional area for passing fluid as possible.

[0131] Figure 15(a) is a front view of the housing shown in Figure 13. Figure 15(b) is a longitudinal section view thereof.

[0132] The housing 12 as a whole is in the form of a flange. One flange side is an attachment side 12a to which the junction tube 11 is attached. The attachment side 12a is provided with female attachment screw holes 12aa for the attachment equally spaced on a predetermined circle.

[0133] A center portion of the attachment side 12a forms a housing hole 12b for housing the second butt valve element 13 in such a manner that the second butt valve element 13 can be slid. A bottom side 12c of the housing hole 12b is provided with a groove 12d for fitting the spring 16 which gives a biasing force toward the junction tube 11 to the second butt valve element 13.

[0134] A penetrating hole 12e for providing a passage for fluid is provided at a center portion of the bottom side 12c, reaching a protruding side 12f on the opposite side of the housing 12. The protruding side 12f abuts the junction side of the auxiliary connection device 15. A step side 12g at the peripheral of the protruding side 12f is provided with female attachment screw holes 12ga for attaching the auxiliary connection device 15 which are equally spaced on a predetermined circle. Figure 16 is a diagram for explaining the principle of the coalescing linkage mechanism of the male coupling in Figure 1. [0135] The coalescing linkage mechanism of the present invention comprises a reversing mechanism which easily and certainly maintains coalescence lock in corporation with the coalescing lock maintaining mechanism. Hereinafter, the coalescing linkage mechanism and the reversing mechanism will be described.

[0136] In Figure 16, symbols A, B, C and D correspond to the fixation point A, the pivot B of the coalescing manipulation lever Id, the linkage supporting point C, and the linkage supporting point D of the connecting plate lb shown in Figure 1. A line through the fixation point A and the pivot B corresponds to the linkage fixing plate la, i.e., the outer tube 4 in Figure 1. A line through the supporting points B and C corresponds to the coalescing manipulation lever Id. A line through the supporting points C and D corresponds to the linking plate lc. The linkage supporting point D corresponds to the movements of the valve tube 5 and the lock tube 2.

[0137] According to this linkage model, it can be understood how the valve tube 5 and the lock tube 2 are slid back and forth when the coalescing manipulation lever Id is rotated. Specifically, when the coalescing manipulation lever Id is rotated to the right (in a direction indicated by a solid line arc with an arrow in Figure 16) in such a manner that the linkage supporting point C is transitioned from state [0] to [1], [2], [3], [4], [5], and [6] in this order. In response to this, the linkage supporting point D is slid in the back and forth directions of the valve tube 2 from state [0] to [1], [2], [3], [4], [5], and [6] in this order. [0138] In state [5] in Figure 16, the orientation of the coalescing manipulation lever

Id is identical to the orientation of the linking plate lc. In this case, an arc BC is obtained by linkage B-C drawing an arc about the supporting point B. An arc DC is obtained by linkage

C-D drawing an arc about the supporting point D.

[0139] As can be seen from comparison between the arc DC and the arc BC, state [5] is a furthest forward destination of the supporting point D which is slid forward. In this case, the coalescing manipulation lever Id is further rotated to the right, i.e., to state [6], the supporting point D is conversely slid backward.

[0140] In this situation, the supporting point D is consistently given a backward biasing force with respect to the outer tube 4 by the spring.41 between the outer tube 4 and the valve tube 5. The biasing force is indicated with an open arrow in Figure 16. Therefore, if the supporting point D goes beyond state [5], the coalescing manipulation lever Id is given a biasing force so as to be further rotated clockwise, thereby maintaining state [6]. In other words, even if a hand which was used to rotate the coalescing manipulation lever Id is released so that the coalescing manipulation lever Id is, left unattended, state [6] can be maintained.

[0141] Such a mechamsm comprising the coalescing linkage mechanism 1 is referred to as a reversing mechanism.

[0142] Note that the coalescing manipulation lever Id is not further rotated from state

[6] in the coalescing direction. This is because the lever Id abuts the lock tube 2 as an outer portion of the male coupling 10 or the like. A stopper may be optionally provided.

[0143] Figure 17(a) is a diagram for explaining the lock releasing state of the coupling in Figure 1. Figure 17(b) is a diagram for explaining the lock maintaining state.

Referring to these figures, coupling coalescence and lock maintenance/release in the cryogenic fluid coupling of the present invention provided with a coalescing lock maintaining mechanism will be described.

[0144] The male and female couplings 10 and 20 of the cryogenic fluid coupling 30 are coalesced and connected with each other in the following manner. Initially, the outer tube 4 of the male coupling 10 is externally fitted into the junction tube 11 of the female coupling 20. The male coupling 10 is pushed into the female coupling 20 until the tip of the outer tube 4 abuts a shoulder portion of the junction tube 11. In this case, the scraper ring 4g of the outer tube 4 scrapes off an ice film attached to the outer wall of the junction tube 11, so that the ice film does not interfere with the pushing.

[0145] Note that when the male coupling 10 is separated from the female coupling 20, or after both are coalesced and until fluid seal is forcedly released, each coupling 10 and 20 achieves fluid seal due to auto-seal function (Figures 5 and 13), so that fluid does not leak. [0146] This situation is shown in Figure 17(a). Here, the latch portion 3d of the latch claw 3 is not fitted into the latch groove lib of the junction tube 11. This is because the coalescing manipulation lever Id of the coalescing linkage mechanism 1 is in the lowest state [0], so that the release taper portions 2s and 3s (Figure 9 and 10) of the respective lock tube 2 and the latch claw 3 abut each other to cause the latch claw 3 to be in the lock releasing state. [0147] In this case, if the coalescing manipulation lever Id is manipulated and rotated from state [1] to [6] as shown in Figure 16, the latch portion 3d of the latch claw 3 is first fitted into the latch groove lib of the junction tube 11, so that the coalescence of the male and female couplings is locked, and eventually the male and female couplings come into a state shown Figure 17(b). In Figure 17(b), the positions of the tip portions of the lock tube 2 are indicated by symbols [1] to [6] in accordance with the states shown in Figure 16. [0148] As described in Figure 16, only the valve tube 5 and the lock tube 2 are sequentially slid forward relative to the outer tube 4 in response to the rotation of the coalescing manipulation lever Id. Initially, the tip of the valve tube 5 is slid while abutting the inner Wall of the junction tube 11 of the female coupling, so that the scraper ring 5b, which is the tip portion of the valve tube 5, scrapes off an ice film attached on the inner wall of the junction tube 11. An ice film attached on the outer wall of the valve tube 5 remains the closed space between the junction tube 11 and the valve tube 5. Nevertheless, since the closed space is sufficiently large as compared to the scraped ice, the ice does not interfere with the coalescence of the male and female couplings. [0149] On the other hand, the scraper ring 1 la of the junction tube 11 scrapes off an ice film attached on the outer wall of the valve tube 5. The ice enters a gap between the valve tube 5 and the outer tube 4, or is discharged outward through the ice escape window 4b (Figures 7 and 8) of the outer tube 4, so that the ice does not interfere with the coalescence. [0150] . The fluid seal between the inner wall of the junction tube 11 and the outer wall of the valve tube 5 is maintained by the sealing means 5a provided at the tip of the valve tube 5.

[0151] When the male coupling is further slid into the female coupling, the protruding end 7aa of the male poppet 7 of the first butt valve element 6 of the male coupling abuts the protruding end 14aa of the female poppet 14 of the second butt valve element 13. Thereafter, only the valve tube 5 is further slid forward. The biasing force of the spring 52 (Figure 5) giving a biasing force to the first butt valve element 6 relative to the valve tube 5 of the male coupling is set to be smaller than the biasing force of the spring 16 giving a biasing force to the second butt valve element 13 relative to the junction tube 11 of the female coupling. Therefore, only the first butt valve element 6 of the male couphng is slid in a direction opposite to the forward sliding, i.e., backward, until the gap E is zero and the rear end of the first butt valve element 6 abuts the front end of the auxiliary tube 51 as shown in Figure 5e. [0152] Thereafter, when the valve tube 5 is further slid, the first butt valve element 6 can be slid backward no further. Therefore, the second butt valve element 13 of the female coupling is retracted relative to the junction tube 11 , the fluid seal is released. In this manner, first, the fluid seal between the first butt valve element 6 and the valve tube 5 in^" the male coupling is released and thereafter, the fluid seal between the second butt valve element 13 and the junction tube 11 of the female coupling is released. Thereafter, cryogenic fluid can be supplied and flowed between the male coupling 10 and the female coupling 20. [0153] In this case, immediately before the poppets 7 and 14 of the respective male and female couplings abut each other to release the seal, the closed space fluid-sealed by the junction tube 11 and the valve tube 5 is very small. Therefore, the influence of oxygen contained in outside air can be ignored and gas purging is no longer required. [0154] In this case, the coalescence of the male coupling 10 and the female coupling

20 is locked by the latch claw 3 of the male couphng and the latch groove 1 lb of the junction tube 11 of the female coupling as shown in Figure 17(b). The latch claw 3 is prevented by the protrusion portion 2b of the lock tube 2 (Figure 10) from being rotated in a releasing direction (outward movement to open), so that the lock is maintained. [0155] In this situation, the coalescing manipulation lever Id is in state [6]. Even if a hand is released from the coalescing manipulation lever Id, leaving it unattended, state [6] can be maintained and the lock maintaining state is maintained. Therefore, a worker can do other related tasks.

[0156] When the connection is released and the male and female couplings 10 and 20 are separated from each other, a reverse procedure to the above-described procedure is performed. Also, in this case, the fluid-sealed closed space between the junction tube 11 and the valve tube 5 is very small. Therefore, even if cryogenic fluid remaining in the closed space is discharged into outside air by separating the couplings, the risk of an adverse effect on the environment or ignition and explosion is low and there is substantially no problem in safety. Figure 18 is a diagram showing an exemplary whole system for LNG supply using the cryogenic fluid coupling shown in Figure 1.

[0157] As an example, the LNG supply system 50 employs the cryogenic fluid coupling 30 of the present invention where liquefied natural gas (LNG) is supplied from a base station tank BT as a storage tank to a tank MT of a tank trailer as a mobile unit. [0158] A supply main pipeline PO provided with a pressure gauge PG and a feedback main pipeline PI are connected to the base station tank BT. The supply main pipeline PO is branched into branch supply pipelines PO1, PO2, ..., on which a pressure gauge PG, a flow meter FM, a control valve CN, a loading arm LA, a male coupling 10 are provided in this order, respectively. The feedback main pipeline PI is branched into branch' feedback pipelines PI1, PI2, ..., on which a pressure gauge PG, a flow meter FM, a control valve CN, a loading arm LA, a male coupling 10 are provided in this order, respectively. [0159] The branch supply pipeline PO1 together with the branch feedback pipeline

PI1 each provided with the male coupling 10 are referred to as an LNG supply station 40.

The system 50 is provided with a plurality of LNG supply stations 40.

[0160] Two female couplings 20 for supply and feedback, respectively, are fixed and connected to the tank MT of a tank trailer. The tank MT is supplied with LNG using the couplings successively or alternately. In other words, for a pair of male couplings 10, a number of female couplings 20 are used. In this regard, it is preferable that the female coupling 20 has a simple structure as in the present invention and low cost.

[0161] The LNG supply system 50 employs the cryogenic fluid coupling 30 of the present invention so as to establish a pipeline connection with the tank MT of a mobile unit, whereby gas purging is not required. Therefore, a pipeline for discharging purged gas required when a base station employs conventional flange couplings, an open/close valve required only for opening or closing supply, and the like become unnecessary, thereby making it possible to reduce cost.

[0162] Even when a plurality of stations are installed, it is not necessary to wait for completion of supply to other mobile units. Therefore, convenience of LNG supply is greatly improved, and contamination of the environment due to leakage of purged gas or the like is reduced.

[0163] Since the cryogenic fluid coupling 30 is provided with the coalescing lock maintaining mechanism 8, the male coupling 10 can be left unattended if the coalescence is locked and other related tasks can be carried out. Therefore, workability is improved.

Moreover, when releasing, only manipulation of the coalescing linkage mechanism is required. Therefore, manipulation is easy.

[0164] Each male coupling 10 alone exhibits a coalescence lock maintaining function without being combined with another male coupling 10. The male coupling 10 can be used in the case where a supply pipeline and a feedback pipeline when cryogenic fluid is supplied are independently installed at different positions, or the case where no feedback pipeline is required. Therefore, the scope of application is large. [0165] Note that the coalescing lock maintaining mechanism characterizing the cryogenic fluid coupling of the present invention can be combined with not only the coupling in the above-described examples but also a cryogenic fluid coupling having a similar function. The coalescing lock maintaining mechanism is also not limited to the above- described combination of a latch claw, a lock tube, and the coalescing linkage mechanism comprising the reversing mechanism, and various modifications are possible. [0166] For example, a latch claw may be consistently given a biasing force toward the lock releasing side, and a lock tube is used to regulate the lock/release of the latch claw. In this case, a separate releasing means is not required. Moreover, the latch claw may be concave while the latch groove may be convex.

[0167] In the above-described examples, a female coupling is provided in a mobile unit while a male coupling is provided in a base station. According to embodiments of supply of cryogenic fluid, a female coupling is provided in a base station while a male coupling is provided in a mobile unit. [Effects of the Invention]

[0168] According to the cryogenic fluid coupling of claim 1 in which male and female couplings are coalesced so that fluid can be supplied, a coalescing lock maintaining mechanism for maintaining or releasing coalescence of male and female couplings in association with a coalescing linkage mechanism is integrated with the cryogenic, fluid coupling comprising the coalescing linkage mechanism. Therefore, the cryogenic fluid coupling can be used alone while solving the ice and gas purging problems. The scope of application of the coupling is large. After connection and coalescence, a worker can release and leave the coupling unattended and do other related tasks, thereby making it possible to improve efficiency

[0169] According to the cryogenic fluid coupling of claim 2, in addition to the effect of claim 1, the structure of the coupling capable of supplying cryogenic fluid without gas purging is claπfied, and the structure of the coalescing lock maintaining mechanism is also clarified in the structure of the coupling. Specifically, the coalescing lock maintaining mechanism has a simple configuration in which in the male coupling, a latch claw is provided in the outer tube and a lock tube is provided in such a manner that the lock tube is slid outside the outer tube in association with the coalescing linkage mechanism, while in the female coupling, a latch groove is provided at the outer wall of the front edge of the junction tube. Thereby, the coalescing lock maintaining mechanism as a unit can be achieved without increasing the cost of the entire coupling much.

[0170] According to the cryogenic fluid coupling of claim 3, in addition to the effect of claim 2, lock/release can be achieved simply by providing a release taper portion on the lock tube and the latch claw. The lock/release is also carried out in association with the coalescing linkage mechanism. The configuration is simple and the cost is reduced! [0171] According to the cryogenic fluid coupling of claim 4, in addition to any of the effects of claims 2 and 3, means for removing ice is further provided, thereby making it possible to coalesce male and female couplings without an influence of an ice film generated on the coupling due to cryogenic fluid.

[0172] According to the cryogenic fluid coupling of claim 5, in addition to any of the effects of claims 2 to 4, the seal portions of the first butt valve element and the second butt valve element are removable and exchangeable. Therefore, the seal portion, which is the most important portion and is most frequently contacted and removed when the coupling is used so that abrasion often occurs, is exchangeable. The coupling can be continuously used by exchanging such a portion without reducing sealing performance, thereby making it possible to reduce cost.

Claims

1. A cryogenic fluid coupling for use in transporting cryogenic fluid, such as liquefied natural gas (LNG), between a storage tank and a mobile unit, wherein a male coupling comprising a coalescing linkage mechanism having a coalescing manipulation lever is coalesced with a female coupling so as to transport fluid, wherein the cryogenic fluid coupling comprises a coalescing lock maintaining mechanism; and when the male coupling, and the female coupling are fitted together by insertion and the coalescing manipulation lever is operated, fitting means provided for the male coupling and the female coupling are actuated, thereby maintaining the coalescence of the male coupling and the female coupling.

2. A cryogenic fluid coupling for use in transporting cryogenic fluid, such as liquefied natural gas (LNG), between a storage tank and a mobile unit, wherein a male coupling is coalesced with a female coupling so as to transport fluid,

• wherein the male coupling comprises a coalescing linkage mechanism having a first butt valve element provided with material flowing holes on a peripheral wall thereof, a valve tube provided with a material opening at a storage tank side and a valve port at a female coupling side, in which the valve port is closed by the first butt valve element consistently given a biasing force, an outer tube housing the valve tube, in which the valve tube is consistently given a biasing force in a non-coalescing direction, and a coalescing manipulation lever, wherein the coalescing manipulation lever is operated so that the valve tube is shifted relative to the outer tube to a coalescence position, the female coupling comprises a second butt valve element provided with a material flowing hole at a peripheral wall thereof, and a junction tube provided with a material opening at a mobile tank side thereof and a valve port at a male coupling side thereof, in which the valve port is closed by the second butt valve element consistently given biasing force, the cryogenic fluid coupling further comprises a coalescing lock maintaining mechanism, wherein the coalescing lock maintaining mechanism comprises at least a latch claw pivoted at an appropriate position of an outer wall of the outer tube of the male coupling while being given a biasing force in a locking direction, a lock tube moved back and forth outside the outer tube in association with the valve tube, and a latch groove provided at a position of the junction tube of the female coupling corresponding to the latch claw, thereby, when the outer tube of the male coupling is fitted into the junction tube of the female coupling by insertion, the latch claw is locked by the latch groove; thereafter, when the coalescing manipulation lever is operated in a coalescing direction, the valve tube is shifted so that the first and second butt valve elements abut each other, whereby the valve ports of the valve tube of the male coupling and the junction tube of the female coupling are opened and cryogenic fluid is permitted to be transferred while the lock tube covers the latch claw so as to maintain disabling of release of the lock state.

3. The cryogenic fluid coupling of claim 2, wherein a releasing taper portion is provided at a back side and rear portion of the latch claw and at an inner wall of a front edge of the lock tube, and when the lock tube is positioned at a rear end, the releasing taper portions abut each other so that the latch claw is moved in a lock releasing direction.

4. The cryogenic fluid coupling of any of claim 2 or 3, wherein the male coupling and the female coupling comprise ice removing means for scraping off ice generated by cryogenic fluid; and the ice removing means comprises at least a scraper ring comprising a front edge of the outer tube of the male coupling, an ice escape hole provided at an appropriate position of the outer tube, a scraper ring provided at a tip of the valve tube of the male coupling, and a scraper ring comprising a front edge of the junction tube of the female coupling.

5. The cryogenic fluid coupling of any of claims 2 to 4, wherein the first butt valve element of the male coupling has a sealing portion abutting the male coupling and the second butt valve¹ element of the female coupling has a sealing portion abutting the male coupling; and the sealing portions are exchangeable.