WO2010090054A1

WO2010090054A1 - Overfilling prevention device for dme fuel tank

Info

Publication number: WO2010090054A1
Application number: PCT/JP2010/050255
Authority: WO
Inventors: 秀幸稲垣; 恵司岩月
Original assignee: 中央精機株式会社
Priority date: 2009-02-04
Filing date: 2010-01-13
Publication date: 2010-08-12
Also published as: JP2010180921A

Abstract

An overfilling prevention device for a DME fuel tank, capable of operating accurately and stably so that a DME fuel tank is not filled with DME fuel to a level exceeding a maximum filling level of the DME fuel tank. A diaphragm type overfilling prevention device, configured in such a manner that a diaphragm provided on the rear side of a main outlet, from which a DME fuel flows into a DME fuel tank, and forming a variable closed region which is separated in a sealed manner from the main outlet side is formed by layering a synthetic rubber plate and a metallic plate on each other in the thickness direction of the diaphragm, with the metallic plate provided on the variable closed region side. The configuration enables the diaphragm to operate accurately and stably even if filling of the tank with the DME fuel and consumption of the DME fuel are repeatedly performed, and also enables both a function of filling the tank with the DME fuel and a function of preventing overfilling of the tank with the DME fuel to be stably performed for a relatively long period.

Description

Overfill prevention device for DME fuel tank

The present invention relates to an overfilling prevention device for a DME fuel tank that is provided in a DME fuel tank that stores DME (dimethyl ether) as fuel and prevents overfilling of the DME fuel into the DME fuel tank.

For example, vehicles such as automobiles tend to increase the number of vehicles using liquefied gas fuel for the purpose of low pollution in accordance with the recent tightening of exhaust gas regulations. As the liquefied gas fuel, liquefied petroleum gas (hereinafter referred to as LPG) fuel is mainstream, but dimethyl ether (hereinafter referred to as DME) fuel is also attracting attention. This DME fuel has an excellent advantage that it has a high cetane number, and can significantly reduce the emission amount of PM and NOx, and is also highly expected as a low pollution measure.

By the way, in the fuel tank for storing the LPG fuel described above, generally, a liquid level display device for confirming the storage amount of the LPG fuel, or a predetermined value when filling the fuel tank with the LPG fuel. An overfilling prevention device or the like for preventing the filling from exceeding the specified maximum filling amount is attached.

Here, as the overfill prevention device, for example, as in Patent Document 1, a float that floats according to the liquid level of the LPG fuel stored in the fuel tank is provided, and the float becomes the maximum filling amount of the fuel tank. There has been proposed one in which the filling of LPG fuel is forcibly stopped when the liquid level is reached. In the overfilling prevention device of Patent Document 1, a diaphragm is provided in the interior of the inflow port into which the LPG fuel flows, and an outflow port through which the LPG fuel flows out on one side of the diaphragm, the inflow port, An annular inflow chamber that communicates with the diaphragm chamber, and a diaphragm chamber provided on the other side of the diaphragm, further comprising a pore communicating with the annular inflow chamber, and a pilot valve interlocked with a float in the tank; It has become. In this configuration, when the LPG fuel is filled, since the float is lowered, the pilot valve is open, so the LPG fuel that has flowed into the diaphragm chamber from the pores is removed from the gap between the pilot valve and its valve seat. It flows out into the tank. At this time, since substantially the same pressure acts on both sides of the diaphragm, the outlet is opened and maintained by the diaphragm, and the LPG fuel flowing in from the inlet enters the tank from the outlet through the annular inlet chamber. leak. On the other hand, when the LPG fuel reaches the maximum filling amount, the float rises and closes the pilot valve, so that the pressure in the diaphragm chamber is increased by the LPG fuel flowing into the diaphragm chamber from the pores, and the diaphragm passes through the outlet. Close. In this way, the diaphragm-type overfill prevention device that prevents overfilling by the operation of the diaphragm, when filling the LPG fuel, forcibly closes the outlet when the maximum filling amount is reached so as to prevent further filling. ing.

JP 2001-263598 A

In the case of using the DME fuel described above, since this DME fuel is a high-pressure gas similar to the LPG fuel, it is possible to utilize the equipment for the LPG fuel. That is, the fuel tank provided with the liquid level display device and the overfill prevention device described above is used. Here, in the overfilling prevention device disposed in the fuel tank for LPG fuel, in the case of the configuration provided with the above-described diaphragm, generally, the diaphragm is synthesized so as to exhibit high sealing performance. A structure formed of rubber or a structure in which a metal plate is embedded in a synthetic rubber is applied. As synthetic rubbers, those using nitrile rubber (NBR) are well known.

However, when DME fuel is stored in a fuel tank for LPG fuel provided with an overfilling prevention device having a diaphragm made of nitrile rubber, the usage period elapses by repeatedly filling and consuming the DME fuel. Accordingly, the operation of the overfill prevention device tends to become unstable. Specifically, there is a concern that when the overfill prevention device fills DME fuel, it does not operate even when the specified maximum fill amount is reached, and overfills beyond the maximum fill amount. Is done. If the DME fuel is stored in the fuel tank for LPG fuel in this way, there is a concern that the problem that the overfill prevention device does not operate normally with the passage of the use period is concerned.

The present invention proposes an overfilling prevention device for a DME fuel tank that is disposed in a DME fuel tank that stores DME fuel and that can operate accurately and stably so as not to fill the DME fuel beyond the maximum filling amount.

The present invention is connected to a gas flow path for allowing DME fuel to flow into the DME fuel tank by opening a filling valve disposed outside the DME fuel tank, and is disposed in the DME fuel tank. A casing body for preventing overfilling of DME fuel, comprising a connecting pipe connected to a gas flow path, and a main outlet through which the DME fuel flows into the DME fuel tank via the connecting pipe And a variable closed region that is disposed behind the main flow outlet in the casing body and is hermetically partitioned from the main flow outlet side, and is converted into a closed position for closing the main flow outlet and an open position for opening the main flow outlet A diaphragm that is provided in the casing body and that always communicates with the variable closed region and the connecting pipe line, and is supported by the casing body and follows the liquid surface height of the liquefied gas stored in the liquefied gas container. A float that floats, a valve body that opens and closes a secondary outlet that allows the DME fuel that has flowed into the variable closed region to flow into the DME fuel tank as the float floats, and the secondary outlet that is closed In the overfilling prevention device for a DME fuel tank provided with a valve urging means for urging in the direction to be moved, the diaphragm is formed by laminating a synthetic rubber plate and a metal plate in the plate thickness direction. An overfilling prevention device for a DME fuel tank, characterized in that the plate is disposed in the casing body with the variable closing region side.

In the configuration of the present invention, when the amount of fuel stored in the DME fuel tank is less than the predetermined maximum filling amount, the DME fuel that has flowed into the movable closed region via the narrow channel by the filling of the DME fuel is floated. As a result, the DME fuel flows out from the secondary outlet that opens against the valve urging means, and DME fuel flows out from the main outlet with the diaphragm at the open position. As a result, the DME fuel tank is filled with DME fuel. When the maximum filling amount is reached, the valve body closes the secondary outlet according to the valve urging means, so that the diaphragm is repositioned to the closed position by the DME fuel flowing into the movable closed region via the narrow channel. . As a result, the filling of the DME fuel is forcibly stopped so as not to exceed the maximum filling amount. In the present invention, DME is dimethyl ether.

Here, as a result of the examination of the suitability of DME fuel by the present inventors regarding the above-described diaphragm-type overfill prevention device used for a fuel tank for LPG (liquefied petroleum gas) fuel Will be explained.
Since DME is highly soluble in organic compounds, it has erosion properties into plastics and rubbers. Therefore, if DME fuel is filled in a fuel tank provided with a conventional overfill prevention device having a diaphragm formed of a synthetic rubber (for example, nitrile rubber), the DME fuel comes into direct contact with the diaphragm. The diaphragm will swell. In particular, since the DME fuel is present in the variable closed region not only at the time of filling but also when the filling outlet is stopped and the secondary outlet is closed, the synthetic rubber of the diaphragm tends to swell on the variable closed region side. When the volume of the variable closed region becomes narrow due to swelling of the diaphragm, it is difficult for the DME fuel to flow into the variable closed region, which may cause malfunction. For example, if the volume of the variable closed area is reduced, DME fuel will not easily flow out from the secondary outlet. It is easy to cause the malfunction of not doing. As described above, when the volume of the variable closed region is reduced due to the swelling of the synthetic rubber constituting the diaphragm, it is possible that the malfunction of the overfilling prevention device may be caused. On the other hand, even in the conventional configuration provided with a diaphragm in which a metal plate is embedded inside a synthetic rubber, the problems caused by swelling of the synthetic rubber described above can occur in the same manner because the front and back surfaces are made of synthetic rubber.

In view of the above, in the fuel tank for LPG fuel, in the configuration in which the overfill prevention device including the diaphragm formed of synthetic rubber or the diaphragm in which the metal plate is embedded in the synthetic rubber is disposed, the DME fuel It is clear that the fuel cannot be charged accurately and stably when the fuel is stored. Based on the results of this study, the inventors of the present invention have studied an overfill prevention device that can stably fill fuel even when DME fuel is stored, and as a result of earnest study, the DME according to the present invention has been studied. It came to invent the overfill prevention device for fuel tanks.

The present invention has a configuration in which a diaphragm formed by laminating a metal plate and a synthetic rubber plate in the thickness direction is arranged so that the metal plate is on the variable closed region side. In such a configuration, the metal plate can prevent the DME fuel that has flowed into the variable closing position from contacting the synthetic rubber plate, so that the synthetic rubber plate can be prevented from swelling in the variable closing region. The area can be maintained. Therefore, when DME fuel is filled, the DME fuel that has flowed into the variable closed region can appropriately flow out from the auxiliary outlet, and the diaphragm can be stably maintained at the open position. When the maximum filling amount is reached, the sub-flow outlet is closed, so that the internal pressure in the variable closing region increases and the diaphragm can be accurately and stably converted to the closed position. As a result, the DME fuel is not filled beyond the maximum filling amount. As described above, since the diaphragm is accurately and stably converted into the open position and the closed position, the function of filling DME fuel and preventing overfilling can be stably performed.

Here, as the synthetic rubber plate, the above-mentioned nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), or the like can be suitably used. In particular, as the hydrogenated nitrile rubber, by appropriately setting the amount of acrylonitrile and the like, the resistance to DME fuel can be improved, so that the hydrogenated nitrile rubber can be used more suitably. Moreover, as a metal plate, plates, such as carbon steel, stainless steel, and an aluminum alloy, can be used.

Also, the narrow channel can be either a configuration provided in the casing body or a configuration provided in the diaphragm. In the case of the latter, what is comprised by the narrow flow hole which penetrates in the plate | board thickness direction of a diaphragm and always connects a variable closed area and a connecting pipe line can be used suitably.

Also, as the shape of the diaphragm, a circular or elliptical plate-like configuration can be suitably used. In particular, the elliptical configuration can be used more suitably because the main flow outlet can be similarly elliptical to increase the outflow rate, and the filling time can be shortened.

Further, the metal plate constituting the diaphragm is formed in a larger area than the main outlet so as to cover the main outlet through the synthetic rubber plate at the closed position. It can be suitably used. In such a configuration, due to the rigidity of the metal plate, the diaphragm can be stably converted between the open position and the closed position, and when the main outlet is closed, the diaphragm made of synthetic rubber is sufficient. Sealability can be exhibited stably.

Further, a configuration in which the portion of the synthetic rubber plate exposed to the variable closed region side is made as small as possible by using a metal plate is preferable. Thereby, the swelling of the synthetic rubber plate can be further suppressed, and the above-described effects are further improved.

As described above, the present invention is a diaphragm-type overfill prevention device, in which the diaphragm is formed by laminating a synthetic rubber plate and a metal plate in the thickness direction, and the metal plate is placed in a variable closed region. Since it is set as the structure arrange | positioned as a side, the swelling of the synthetic rubber plate by the DME fuel which flowed into the variable closed region can be suppressed by the metal plate. As a result, even when DME fuel is repeatedly charged and consumed, the diaphragm operates accurately and stably, and the function of filling DME fuel and the function of preventing overfilling are stable over a relatively long period of time. Can be demonstrated.

1 is a cross-sectional view of a DME fuel tank 1. FIG. It is sectional drawing showing the state during fuel filling of the overfill prevention apparatus 2 of a present Example. It is sectional drawing showing the filling completion state of the overfilling prevention apparatus 2 same as the above. The diaphragm 7 is (A) a plan view of the main outlet side 16, (B) a plan view of the auxiliary outlet side 17, and (C) a longitudinal sectional view.

Embodiments of the present invention will be described in detail with reference to the accompanying drawings.
In this embodiment, a DME fuel tank 1 for storing DME fuel is disposed in a vehicle such as a truck, for example, and as shown in FIG. 1, a cylindrical body 1a and a body 1a. The hemispherical mirror portion 1b (not shown on one side) joined to both side openings. The DME fuel tank 1 is fixed to a vehicle by a fixing member (not shown), and a valve provided with a filling valve 45 and a filling valve opening / closing handle 41 for opening and closing the filling valve 45 on one mirror portion 1b. A device 40 is provided. The valve device 40 is attached to the mirror portion 1b by fixing the attached member 43 provided on the valve device 40 to an attachment member 48 disposed on the mirror portion 1b. The filling valve 45 is provided with a supply port 46 for supplying DME fuel from the outside. When DME fuel is filled, the DME fuel is supplied from the supply port 46 at a predetermined filling pressure. And is filled with fuel.

In the DME fuel tank 1, a gas filling pipe 42 communicating with the above-described filling valve 45 is disposed. And the tip of this gas filling pipe 42 is arranged in the upper part in DME fuel tank 1, and overfill prevention device 2 is connected to the tip. The gas flow path 9 according to the present invention is constituted by the inside of the gas filling pipe 42.

This overfilling prevention device 2 includes a casing body 3 and a float 10 as shown in FIGS. The casing body 3 includes a casing main body 3a connected to the gas filling pipe 42 and a casing sub body 3b attached to the upper portion of the casing main body 3a. Here, a connecting pipe part 4 that opens downward is provided at the lower part of the casing main body 3a, and the connecting pipe part 4 is fitted around the tip of the gas filling rod 42 and fixed by caulking or the like. The overfill prevention device 2 is connected to the gas filling rod 42. The connecting pipe portion 4 is provided in the vertical direction along the distal end portion of the gas filling rod 42, and the connecting pipe line 11 is constituted by the inside thereof, and the connecting pipe line 11 communicates with the gas flow path 9. At the upper part of the casing main body 3a, an elliptical annular wall 13 is provided along the horizontal direction so as to be substantially perpendicular to the longitudinal direction (vertical direction) of the connection pipe line 11, and surrounds the outer side of the elliptical annular wall 13. In addition, an elliptical annular channel 12 communicating with the connecting pipe 11 is formed. An elliptical main outlet 16 that opens into the DME fuel tank 1 is formed by the inside of the elliptical annular wall 13.

The casing sub body 3b is attached to and integrated with the casing main body 3a so as to cover the annular flow path 12 and the elliptical annular wall 13 of the casing main body 3a. Thereby, the casing body 3 is formed. An operating air region 20 having a substantially elliptical cross section in which a diaphragm 7 described later operates is formed between the casing main body 3a and the casing sub body 3b. The working airspace 20 communicates with the annular flow path 12 and the main outlet 16 inside the elliptical annular wall 13, and also communicates with the connecting pipe line 11 via the annular flow path 12. An inner end 13 a of the elliptical annular wall 13 is disposed in the working air space 20.

The casing sub-body 3b is provided with a sub-outlet 17 that opens into the DME fuel tank 1 so as to face the main outlet 16 in a state of being integrated with the casing main body 3a. In addition, the operating air region 20 and the inside of the DME fuel tank 1 communicate with each other.

An elliptical plate-like diaphragm 7 is disposed in the working airspace 20 formed inside the casing body 3 so as to divide the working airspace 20 into an elliptical annular wall 13 side and a secondary outlet 17 side. Yes. The diaphragm 7 is composed of an elliptical main plate portion 7a and an outer peripheral support edge portion 7b formed on the outer side of the main plate portion 7a (see FIG. 4). The diaphragm 7 is fixed to the casing body 3 by sandwiching and supporting the outer peripheral support portion 7b between the casing main body 3a and the casing sub body 3b. Then, the diaphragm 7 is formed in a hermetically sealed manner with the variable outlet region 21 on the side of the auxiliary air outlet 17 of the working air region 20. The diaphragm 7, the main flow outlet 16 (elliptical annular wall 13), and the sub-flow outlet 17 are arranged so that their center positions are on the same line. Further, since the outer peripheral support edge portion 7b of the diaphragm 7 is formed of a thin synthetic rubber, the diaphragm 7 is closed to close the main outlet 16 in close contact with the inner end 13a of the elliptical annular wall 13 (see FIG. 3) and an open position (see FIG. 2) that is separated from the inner end 13a and communicates with the main outlet 16 and the annular basin 12.

The diaphragm 7 is formed with a trickle hole 7c penetrating in the plate thickness direction at the outer edge of the main plate part 7a facing the annular flow path 12, and the trickle hole 7c is in a closed position. Also, the annular flow path 12 and the variable closed region 21 are communicated. The narrow channel 7c constitutes a narrow channel according to the present invention. The diaphragm 7 is a main part of the present invention and will be described in detail later.

Further, a coil-like spring 22 that urges the diaphragm 7 in the direction of the closed position is disposed in the variable closed region 21.

In the casing body 3, the major axis direction of the elliptical main flow outlet 16 is provided along the longitudinal direction of the connecting pipe portion 4 (longitudinal direction of the distal end portion of the gas filling pipe 42). This is so that the overfilling prevention device 2 and the gas filling pipe 42 can be inserted into the DME fuel tank 1 through an opening (not shown) for attaching the valve device 40 to the mirror portion 1b of the DME fuel tank 1. It is to do. Since the elliptical main flow outlet 16 has an increased opening area in the major axis direction, it has the advantage that the amount of DME fuel flowing out is large and the filling time required for filling can be shortened. Yes.

A valve body 24 having a valve portion 24 a for opening and closing the auxiliary outlet 17 is disposed at the auxiliary outlet 17 of the casing body 3. The valve body 24 is connected to the auxiliary outlet by a coiled spring 25. It is urged to close 17. Here, the spring 25 constitutes the valve biasing means according to the present invention.

Further, a tilting plate 27 that abuts on the outer end 24b of the valve body 24 described above is pivotally supported on the casing body 3 on the outside thereof. The lower portion of the tilting plate 27 abuts on the outer end portion 24 b of the valve body 24, and the substantially central portion thereof is pivotally supported by the casing sub body 3 b constituting the casing body 3. Further, a support rod 29 provided with the above-described float 10 at the tip is connected to the upper portion of the tilting plate 27. The float 10 floats according to the liquid level of the DME fuel stored in the DME fuel tank 1.

Here, when there is little DME fuel, the float 10 descends, the tilting plate 27 pushes the valve body 24 into the casing body 3 against the urging force of the spring 25, and opens the auxiliary outlet 17. . In the present embodiment, the casing body 3 is provided with a stop piece 28 for defining the lowest lowered position of the float 10. Thereby, the tilting plate 27 defines the position where the valve body 24 is pushed most. On the other hand, as the float 10 rises due to the filling of DME fuel, the tilting plate 27 tilts in a method of reducing the load acting on the valve body 24 (direction away from the valve body 24). Thereby, the valve body 24 moves in the direction of closing the auxiliary outlet 17 according to the urging force of the spring 25. The DME fuel tank 1 has 85% of the tank capacity set as the maximum filling amount of DME fuel. When the float 10 comes to a position where it floats at the level of the DME fuel stored at the maximum filling amount, the tilting plate 27 tilts to the tilting position where the auxiliary outlet 17 is closed by the valve body 24.

The operation of such an overfill prevention device 2 will be described.
When the DME fuel stored in the DME fuel tank 1 is smaller than the above-mentioned maximum filling amount, the float 10 is lowered. Therefore, the valve body 24 is pushed by the tilting plate 27 in conjunction with the float 10 and the side flow is performed. The outlet 17 is opened (see FIG. 2). In this state, the diaphragm 7 is maintained in the closed position by the urging force of the spring 22 (not shown). When the DME fuel is filled, the filling pressure of the DME fuel flowing from the filling valve 45 through the gas filling pipe 42 acts on the diaphragm 7 via the annular flow path 12 of the casing body 3. Here, since the auxiliary outlet 17 is open, the internal pressures of the variable closed region 21 and the DME fuel tank 1 are the same. Therefore, the diaphragm 7 is moved from the closed position to the open position against the biasing force of the spring 22 by the filling pressure, and the main outlet 16 is opened as shown in FIG. As a result, the DME fuel that has flowed from the gas flow path 9 of the gas filling pipe 42 flows out from the main outlet 16 into the DME fuel tank 1 through the connection pipe line 11 and the annular flow path 12 of the casing body 3. Further, the DME fuel also flows into the variable closed region 21 through the trickle hole 7 c of the diaphragm 7 and flows out into the DME fuel tank 1 from the auxiliary outlet 17.

Then, as the DME fuel stored in the DME fuel tank 1 increases and the liquid level height rises, the float 10 moves up. By tilting the tilting plate 27 in conjunction with the ascent of the float 10, the force that pushes the valve body 24 by the tilting plate 27 is reduced, and the valve body 24 is accordingly sub-flow outlet according to the biasing force of the spring 25. It moves gradually in the direction of closing 17. When the DME fuel reaches the maximum filling amount, the valve body 24 closes the auxiliary outlet 17 according to the urging force of the spring 25 as shown in FIG. Thereby, the internal pressure of the variable closed region 21 is increased by the DME fuel flowing from the trickle hole 7c of the diaphragm 7, and the diaphragm 7 is converted into the closed position by the internal pressure. Since the DME fuel flowing in from the gas filling pipe 42 cannot flow out from the main outlet 16 and the filling of the DME fuel into the DME fuel tank 1 is forcibly stopped, charging exceeding the maximum filling amount is performed. Can be prevented.

Thereafter, when the DME fuel is consumed, the float 10 descends, so that the tilting plate 27 pushes the valve body 24 into the casing body 3 and the auxiliary outlet 17 is opened. At this time, since the filling of the DME fuel from the filling valve 45 is stopped, the filling pressure does not act on the diaphragm 7, so that the diaphragm 7 is maintained in the closed position by the urging force of the spring 22.

Next, the diaphragm 7 according to the present invention will be described in detail.
As shown in FIG. 4, the diaphragm 7 is formed by laminating a synthetic rubber plate 31 and a metal plate 33 so as to overlap each other in the plate thickness direction and bonding them together to be integrated. Here, the synthetic rubber plate 31 is composed of an elliptical main plate portion 32 and the outer peripheral support edge portion 7b formed around the outer periphery of the main plate portion 32. Is formed. The main plate portion 32 is formed to be thicker than the outer peripheral support edge portion 7b, has a flat surface with a uniform back surface on which the metal plate 33 is superimposed, and protrudes outward in the center of the surface. A head-cone-shaped protrusion 32a is provided.

The metal plate 33 has substantially the same elliptical shape as the main plate portion 32 of the synthetic rubber plate 31 described above, and the surface to be bonded to the back surface of the main plate portion 32 has a flat surface shape. A protrusion 33a that protrudes in a columnar shape toward the back is provided at the center of the back surface on the opposite side. The protrusion 33a is positioned by fitting the tip of the spring 22 described above.

The metal plate 33 and the main plate portion 32 of the synthetic rubber plate 31 constitute the main plate portion 7a of the diaphragm 7 described above. Further, the main plate portion 32 of the synthetic rubber plate 31 and the metal plate 33 form an elliptical shape similar to the elliptical shape constituting the elliptical annular wall 13 of the casing body 3. The size and shape is one size larger than that. Therefore, in the state where the diaphragm 7 is in the closed position in the casing body 3, the outer peripheral edge portion of the metal plate 33 passes through the annular flow path 12 of the casing body 3 outside the main plate portion 32 of the synthetic rubber plate 31. It is made to cover partially (or entirely) through the peripheral edge (see FIG. 3).

Here, in the present embodiment, the metal plate 33 is made of steel steel. The synthetic rubber plate 31 is made of hydrogenated nitrile rubber (HNBR). This hydrogenated nitrile rubber is obtained by chemically hydrogenating unsaturated bonds contained in the main chain of nitrile rubber (NBR). In this embodiment, the amount of acrylonitrile is appropriately adjusted so as to improve the resistance to DME fuel, and the swelling phenomenon caused by exposure to DME fuel can be suppressed as much as possible. Therefore, by applying as a constituent material of the diaphragm, the durability of the diaphragm is improved, and the overfill prevention device operates appropriately and stably.

Furthermore, a plate thickness ratio between the plate thickness of the metal plate 33 and the plate thickness of the synthetic rubber plate 31 is set. In this embodiment, the synthetic rubber plate 31 is about 2.5 times as large as the metal plate 33. The plate thickness ratio is preferably set so that the plate thickness of the synthetic rubber plate 31 with respect to the metal plate 33 is 1.0 to 5.0. This is because when the plate thickness ratio is smaller than 1.0, the plate thickness of the synthetic rubber plate 31 is reduced, so that the resistance to DME fuel is reduced, or when the plate thickness of the metal plate 33 is increased, the weight is increased. To increase. On the other hand, if the plate thickness ratio is larger than 5.0, the plate thickness of the metal plate 33 becomes thin, so that the rigidity decreases, or if the plate thickness of the synthetic rubber plate 31 becomes thick, the weight increases.

The diaphragm 7 formed by integrating the metal plate 33 and the synthetic rubber plate 31 is formed on the casing body 3 such that the metal plate 33 side becomes the side outlet 17 (casing side body 3b) side. Arranged in the operating airspace 20. Specifically, when the casing main body 3a and the casing sub body 3b are attached and integrated, the outer peripheral support edge portion 7b of the diaphragm 7 is sandwiched between the casing main body 3a and the casing sub body 3b, thereby The diaphragm 7 is disposed in the working air space 20 formed in the casing body 3. As a result, a variable closed region 21 is formed in the working air region 20 formed in the casing body 3 in a sealed manner from the main outlet 16 side. Here, in the diaphragm 7, the metal plate 33 is on the side of the auxiliary outlet 17, and the main plate portion 32 of the synthetic rubber plate 31 is on the side of the main outlet 16.

In addition, the metal plate 33 and the main plate portion 32 of the synthetic rubber plate 31 are provided with the

pores

33b and 32b having the same dimensions and constituting the narrow flow holes 7c of the diaphragm 7 in the plate thickness direction. As shown in FIG. By integrating the metal plate 33 and the synthetic rubber plate 31, both the

pores

32b and 33b communicate with each other to form the trickle hole 7c. In the state where the diaphragm 7 is disposed in the casing body 3, as described above, the trickle hole 7c is formed at the outer peripheral edge of the diaphragm 7 so as to be opposed to the annular flow path 12, and is variable. The closed region 21 is always in communication with the gas flow path 9 of the gas filling pipe 42 via the annular flow path 12 and the connection pipe line 11 of the connection pipe portion 4.

As described above, the diaphragm 7 arranged in the casing body 3 as described above moves to the side of the auxiliary outlet 17 by receiving a filling pressure from the annular flow path 12 when filling with DME fuel. Then, the protrusion 33a of the metal plate 33 is positioned at a position where the auxiliary outlet 17 is not closed by the biasing force of the spring 22 that biases the diaphragm 7 toward the closed position. This positioned position is an open position. That is, the minimum volume of the variable closed region 21 is determined by the filling pressure of DME fuel and the biasing force of the spring 22.

When the DME fuel is filled, the DME fuel flows from the annular flow region 12 to the inside of the elliptical annular wall 13 by the synthetic rubber plate 31 of the diaphragm 7 and flows out from the main outlet 16. Here, since the frustoconical protrusion 32a is formed at the center of the synthetic rubber plate 31, the DME flows from the annular basin 12 toward the center along the surface of the synthetic rubber plate 31. The fuel is easy to flow toward the main outlet 16.

Further, during the filling of the DME fuel, the metal plate 33 of the diaphragm 7 is exposed to the DME fuel by the DME fuel that has flowed into the variable closed region 21 through the trickle hole 7c of the diaphragm 7. Further, the metal plate 33 of the diaphragm 7 is exposed to the DME fuel stored in the variable closed region 21 even when the DME fuel reaches the maximum filling amount and the auxiliary outlet 17 is closed. Thus, even if the metal plate 33 of the diaphragm 7 is exposed to the DME fuel, the metal plate 33 is hardly eroded, so that the operation of converting the position of the diaphragm 7 between the open position and the closed position can be stably performed.

Here, as described above, in the overfilling prevention device having a synthetic rubber diaphragm in which a metal plate is embedded, the synthetic rubber constituting the diaphragm is exposed in the variable closed region. Therefore, the synthetic rubber swells by repeated and continuous exposure to the DME fuel. In particular, in this diaphragm, the synthetic rubber tends to swell easily due to the structure in which the metal plate is arranged inside. If the synthetic rubber swells, the volume of the variable closed area will be reduced, so that the DME fuel that has flowed into the variable closed area becomes difficult to flow in from the secondary outlet, resulting in malfunction of the diaphragm. Can occur.

In contrast to such a conventional configuration, the overfilling prevention device 2 according to the present invention swells the synthetic rubber by the DME fuel because the metal plate 33 is exposed to the variable closed region 21 side as described above. Can be sufficiently suppressed. Therefore, the diaphragm 7 can be operated accurately and stably with the maximum filling amount, and the DME fuel can be stably filled via the overfilling prevention device 2.

The surface of the diaphragm 7 on the side of the main flow outlet 16 is exposed to the DME fuel when DME fuel is filled, but the diaphragm 7 is in an open position at other times than filling. Little contact with DME fuel. Therefore, swelling of the synthetic rubber plate 31 can be suppressed over a relatively long period. In particular, in the present embodiment, the effect of suppressing the swelling is further increased because the hydrogenated nitrile rubber has improved resistance to DME fuel. As a result, the overfill prevention device can operate accurately and stably over a long period of time.

Furthermore, since the diaphragm 7 is dimensioned so that the metal plate 33 partially (or entirely) covers the annular basin 12 as described above, the diaphragm 7 is made of DME fuel. In the case of operating to the open position upon receiving the filling pressure, the position can be stably changed by the rigidity of the metal plate 33 in any case of operating to the closed position due to the increase in the internal pressure of the variable closed region 21. .

The present invention is not limited to the above-described embodiments, and can be appropriately used within the scope of the gist of the present invention. For example, a configuration in which the spring 25 that urges the diaphragm 7 is not provided may be employed. Further, a leaf spring or the like can be used instead of the coiled springs 22 and 25.

1 DME fuel tank 2 Overfill prevention device 3 Casing body 7 Diaphragm 7c Narrow flow hole (narrow flow path)
DESCRIPTION OF SYMBOLS 9 Gas flow path 10 Float 11 Connection pipe line 16 Main outflow port 17 Sub outflow port 21 Variable closed area 24 Valve body 25 Spring (valve biasing means)
31 Synthetic rubber plate 33 Metal plate

Claims

When the filling valve provided outside the DME fuel tank is opened, the DME fuel tank is connected to a gas flow path for allowing the DME fuel to flow into the DME fuel tank, and is disposed in the DME fuel tank. To prevent filling,
A casing body comprising a connecting pipe line connected to the gas flow path, and a main outlet through which the DME fuel flows into the DME fuel tank via the connecting pipe line;
A diaphragm that is disposed behind the main flow outlet in the casing body, forms a variable closed region that is hermetically partitioned from the main flow outlet side, and changes the position between a closed position that closes the main flow outlet and an open position that opens. When,
A narrow channel that is provided in the casing and always communicates with the variable closed region and the connecting pipe;
A float that is pivotally supported by the casing body and floats according to the liquid level of the liquefied gas stored in the liquefied gas container;
A valve body that opens and closes a secondary outlet that allows the DME fuel flowing into the variable closed region to flow into the DME fuel tank as the float floats;
In an overfilling prevention device for a DME fuel tank comprising valve urging means for urging the valve body in a direction to close the auxiliary outlet.
A diaphragm for a DME fuel tank, characterized in that a diaphragm is formed by laminating a synthetic rubber plate and a metal plate in the plate thickness direction, and the metal plate is disposed in the casing body with the variable plateau side. Filling prevention device.