GB2327741A

GB2327741A - Fuel check valve

Info

Publication number: GB2327741A
Application number: GB9815268A
Authority: GB
Inventors: Morihiko Kishi
Original assignee: Piolax Inc
Current assignee: Piolax Inc
Priority date: 1997-07-14
Filing date: 1998-07-14
Publication date: 1999-02-03
Anticipated expiration: 2018-07-14
Also published as: GB2327741B; GB9815268D0

Abstract

A check valve which is mounted between a fuel tank and a fuel supply pipe, includes a sliding type valve body 21. The valve body is provided with a plurality of guiding projections 26 extending up stream. The guiding projections slidingly contact an inner wall surface of the housing of the valve at the up stream side. The valve body may be further guided by an axial portion 30 which slides in a cylindrical portion 42 of a cap 41.

Description

SPECIFICATION TITLE OF THE INVENTION CHECK VALVE BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a check valve, more specifically to an improvement of a fuel back flow check valve which is held between at the connecting hole portion of a fuel tank of an automobile and a fuel supply pipe connected to the fuel tank, and prevents the fuel in the fuel tank from flowing back to the fuel supply pipe side.

Description of the Related Arts As a conventional fuel back flow check valve of this type, for example, there is one shown in Japanese Utility Model Application Publication 3-54031.

The conventional fuel back flow check valve (not shown specifically in the figure) is arranged such that a single or a plurality of valve boards are rockingly held between on the side of the connecting hole portion facing into the fuel tank, of the fuel supply pipe, and at the time of refueling, by the pressure of the flow of the supply fuel, the connecting hole portion of the fuel supply pipe is opened by the single or plurality of valve boards so as to permit the fuel to flow into the fuel tank, and after the refueling1 the connecting hole portion of the fuel supply pipe is closed by the single or plurality of valve boards so as to prevent the fuel from flowing back to the fuel supply pipe side.

However, leaving aside the number of pieces of used valve boards out of the question, basically, a conventional fuel back flow check valve is simply a valve board which is rockingly held between on the connecting hole portion side of the fuel supply pipe and only opens and closes the connecting hole portion, and therefore, it can be never the that the sealing ability is high in the state when the connecting hole portion of the fuel supply pipe is closed. Therefore, for example, in a case where the fuel supply pipe is broken or damaged because of a crash accident or the like, it sufficiently has such a risk that the fuel in the fuel tank may flow back to the fuel supply pipe side because of the lack of the sealing ability.

Furthermore, in the case of using a plurality of valve boards, a devise to forcedly ensure the closing state of each valve board is made for the present by using a spring member together, but it is not possible td improve the sealing ability between respective valve boards only by this.

SUMMARY OF THE INVENTION The present invention has been achieved with such points in mind.

It therefore is an object of the present invention to provide a check valve in which sealing ability can be improved and confirmed to check a fuel back flow between a fuel tank and fuel supply pipe.

To achieve the object, according to a first aspect of the present invention, there is provided a check valve to be mounted at a connecting hole portion between a fuel tank and a fuel supply pipe, comprising: a sliding type valve body to open and close the connecting hole portion, wherein the valve body is provided with a plurality of guiding projections expanding toward the up stream side of the connecting hole portion; and the guiding projections slidingly contact to an inner wall surface constituting the connecting hole portion at the up stream side.

Therefore, according to the first aspect, the plurality of guiding projections slidingly contact to the inner wall surface of the connecting hole portion at the up stream side, so that the valve body can be stably slid without any jamming and any jarring. At the time of refueling, the flow resistance of the fuel can be decreased, and at the time of closing of the connecting hole portion, the function of the sealing can be improved.

According to a second aspect of the present invention, as it depends from the first aspect, wherein the valve body comprises an axial portion expanding toward the down stream side of the connecting hole portion; and the axial portion is slidably supported.

Additionally, according to the second aspect of the invention, the valve body is also supported by the axial portion on the down stream side other than the up stream side with the guiding projections, so that a stable sliding may be secured because of the state that the valve body is supported at both sides thereof.

According to a third aspect, as it depends from the first or the second aspect, wherein the valve body comprises: a conical shoulder portion formed onto the peripheral portion of the valve body and the shoulder portion regulates the flowing direction of the supplied fuel; a flange portion which touches a fringe of the connecting hole portion and which is formed on the down stream side of the valve body; and an elastic sealing portion with a diameter larger than that of the flange portion which is adhered to the fringe of the connecting hole portion from the down stream side of the flange portion.

According to the third aspect of the invention, since the elastic sealing portion with a large diameter adheres to the fringe of the connecting hole portion under the condition of touching the fringe of the connecting hole portion of the flange portion, the sealing ability is much more improved, so that the fuel can surely be prevented from flowing back to the fuel supply pipe side, and at the same time, since the supply fuel is prevented from colliding with the elastic sealing portion with a large diameter as much as possible by the function of the shoulder portion, the permanent deformation by fatigue of the elastic sealing portion with a large diameter may effectively be solved, coupled with the above mentioned touching condition of the flange portion.

According to a fourth aspect of the present invention, there is provided a check valve to be mounted at a connecting hole portion between a fuel tank and a fuel supply pipe, comprising: a sliding type valve body to open and close the connecting hole portion, wherein the valve body comprises: a sliding member which is provided with a plurality of guiding projections expanding toward the up stream side of the connecting hole portion; an elastic sealing member adhering to a fringe of the connecting hole portion; and a pressing member pressing the elastic sealing member to the sliding member side.

According to the fourth aspect of the invention, since the guiding projections of the sliding member slidingly touch the inner wall surface on the up stream' side of the connecting hole portion, the valve body itself can stably be slid without jarring, and at the time of refueling, the flow resistance of the fuel is decreased, and at the time of closing of the connecting hole portion, the elastic sealing member is pressed to the sliding member side by the pressing member, and the elastic sealing member may surely be adhered to the fringe of the connecting hole portion, so that the sealing ability may be improved, and still, the fuel can effectively be prevented from flowing back to the fuel supply pipe side.

The invention described in a fifth aspect is an invention according to the first to the fourth aspect, further comprising: fuel passing cutout holes located on the down stream side of the connecting hole portion, the fuel passing cutout holes partitioned by a plurality of frame walls; and valve body rotation preventing members positioning the guide projections and the frame walls at the corresponding positions.

According to the fifth aspect of the invention, at the time of sliding of the valve body, an unnecessary rotation of the valve body itself can be prevented by the rotation preventing members, and in addition to that, the guiding projections and the frame walls can be positioned at the corresponding positions, and therefore, from this point, the flow resistance of the supply fuel can also be decreased.

The invention described in a sixth aspect is an invention according to the first to the fourth aspect, further comprising: a cap formed with a support cylindrical portion, wherein the valve body is guidedly supported by the inner wall surface of the connecting hole portion through the guiding projections at a position where the valve body closes the connecting hole portion; and the valve body is guidedly supported by the inner wall surface of the connecting hole portion through the guiding projections and supported by the support cylindrical portion through a hole formed at the down stream side portion of the valve body at a position where the valve body opens the connecting hole portion.

In the construction described above, the valve body is guidedly supported by the inner wall surface of the connecting hole portion through the guiding projections and supported by the support cylindrical portion through the hole as a through hole formed at the down stream side portion of the valve body without any sliding member which projects or protrudes from the bottom end of the valve body.

Therefore, the check valve according to the sixth aspect can be used and applicable even in a small-sized auxiliary tank or even in a tank which is provided with a baffle, without any jamming between the projection or the protrusion from the bottom end of the valve body and the baffle or walls of the smallsized auxiliary tank.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS The above and further objects and novel features of the present invention will more fully appear from the following detailed description when the same is read in conjunction with the accompanying drawings, in which: Fig. 1 is an exploded perspective view showing a fuel back flow check valve according to the first embodiment of the present invention; Fig. 2A is a cross sectional view showing a housing; Fig. 2B is a cross sectional view taken along the line IIB-IIB of Fig. 2A; Fig. 3 is a cross sectional view showing a valve body in a disassembled state; Fig. 4 is an explanation view showing the state where the fuel back flow check valve is mounted between a fuel tank and a fuel supply pipe; Fig. 5 is a cross sectional view of the principal part showing the operating state where the connecting hole portion is opened at the time of refueling; Fig. 6 is a cross sectional view of the principal part showing the operating state where the connecting hole portion is closed after the refueling; and Fig. 7A is a cross sectional vie of the principal part showing the fuel back flow check valve according to the second embodiment in the operating state where the connecting hole portion is closed after the refueling; Fig. 7B is an enlarged explanation view of the portion surrounded by a dotted circle in Figs.7A and 8A, and shows the sealing state; Fig. 8A is a cross sectional view of the principal part showing the fuel back flow check valve according to the third embodiment in the operating state where the connecting hole portion is closed; Fig. 8B is a cross sectional view of the principal part showing the fuel back flow check valve according to the third embodiment in the operating state where the valve body is operating; and Fig. 8C is a cross sectional view of the principal part showing the fuel back flow check valve according to the third embodiment in the operating state where the connecting hole portion is opened.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS There will be detailed below the preferred embodiments of the present invention with reference to the accompanying drawings. Like members are designated by like reference characters.

As shown in Fig. 1, the fuel back flow check valve according to the first embodiment comprises: a housing 1 connected to the lower end portion of a fuel supply pipe coupled to the fuel tank; a sliding type valve body 21 slidably supported in the housing 1; a cap 41 attached to the end portion facing into the fuel tank of the housing 1: and a coil spring 51 for urging the valve body 21 in the direction of the fuel supply pipe.

Then, as shown in Fig. 2, the housing 1 is composed of a tank outer portion 2A and a tank inner portion 2B which are separately formed like a cylinder'from a synthetic resin, and the tank outer portion 2A is arranged such that a ring-like convex surface 3 to which the lower end portion of the fuel supply pipe is tightly fitted, is formed on the periphery of the opening at the upper end, and under the convex surface 3, a large ring-like welding piece 4 to be welded to the side wall of a fuel tank made of a resin, is provided to project, and under the welding piece 4, a cylindrical leg wall 5 with connecting windows 5a is provided to hang down.

The tank inner portion 2B is arranged such that onto the inner wall surface of the cylindrical upper portion side thereof, 4 pieces of guiding ribs 6 which guide the guiding blades as the guiding projections of the valve body to be described later and have the relation of pairing, are provided to project, and onto the outer wall surface thereof, a ring-like receiving wall 7 with connecting claws 7a for receiving the leg wall 5 is provided, and on the other hand, the lower portion side is made to have a diameter a little larger than that of the upper portion side through a projecting collar 8. and in the periphery thereof.

large cutout holes 10 which are partitioned by 4 pieces of frame walls 9 and permit the fuel to pass, are opened, and in the periphery of the opening of the lower end, connecting windows 11 to attach the cap 41 are formed. Therefore, in the first embodiment, the inside of the projecting collar 8 of the tank inner portion 2B becomes the connecting hole portion 12 to the fuel tank, and the projecting collar 8 becomes the fringe of the connecting hole portion 12. Furthermore, as shown in Fig.

2B, it is preferable that the four(4) pieces of guiding ribs 6 and four(4) pieces of frame walls 9 are all respectively positioned on the same lines in the circumferential direction, but depending on the difference of the number of pieces or the like, it is also possible that all are not positioned on the same lines.

Accordingly, if the leg wall 5 of the tank outer portion 2A and the receiving wall 7 of the tank inner portion 2B are connected to each other through the connecting windows 5a and the connecting claws 7a while putting a seal ring 13 between them, and onto the peripheral portion thereof, a lock ring 14 is fitted, the tank outer portion 2A and the tank inner portion 2B are integrated as shown in the figure, and in the interior of the integrated housing 1, a fuel passage following on the connecting hole portion 12 is formed.

As shown in Fig. 3, the valve body 21 is composed of a sliding member 22, an elastic sealing member 23, and a pressing member 24. The sliding member 22 is formed from a synthetic resin material to be a conical shape facing to the up stream side of the connecting hole portion 12 and having a hollow interior, and is arranged such that on the peripheral portion of the conical shape, a lifting ring-like shoulder portion 25 for regulating the flowing direction of the supply fuel is formed, and above the shoulder portion 25, 4 pieces of guiding blades 26 whose tip portions enter the respectively corresponding guiding ribs 6 to be connected and slidingly touch the inner wall surface of the tank inner portion 2B of the housing 1, are provided to stand at a constant tilt angle, and at the peripheral fringe on the down stream side, a ring-like flange portion 27 touching the projecting collar 8 as the fringe of the connecting hole portion 12 of the housing 1, is provided.

Furthermore, the elastic sealing member 23 is formed like a ring from an elastic material such as a rubber, and the peripheral fringe thereof is formed to be a thin wall sealing lip portion 28 having a diameter larger than that of the flange portion 27 and bent upward. The pressing member 24 is formed from a synthetic resin material, and is arranged such that it integrally has a head portion 29 facing in the interior of the sliding member 22 and a long axial portion 30 hanging down from the head portion 29, and inside the head portion 29, a ring-like holding portion 31 for holding the upper end portion of the coil spring 51 is formed, and onto the peripheral fringe thereof, a flange portion 32 for holding the elastic sealing member 23 together with the flange portion 27 of the sliding member 22 between them, is provided.

The cap 41 is formed like a disk from a synthetic resin, and is arranged such that at the central portion thereof, a support cylindrical portion 42 with no bottom into which the long axial portion 30 of the pressing member 24 is slidably fitted to be supported, is provided to stand, and around the support cylindrical portion 42, a ring-like holding concave portion 43 for holding the lower end portion of the coil spring 51 is formed, and onto the peripheral surface, a plurality of connecting claws 44 to be connected to the connecting windows 11 formed in the tank inner portion 2B side of the housing 1, are provided.

Accordingly, the fuel back flow check valve can be assembled at the instant, when from the lower end opening side of the integrated housing 1, the sliding member 22, the elastic sealing member 23, and the pressing member 24 are inserted into the housing 1 in turn, and finally, the coil spring 51 is mounted between the holding portion 31 of the pressing member 24 and the holding concave portion 43 of the cap 41, and at the same time, while inserting the axial portion 30 of the pressing member 24 into the support cylindrical portion 42 of the cap 41, the cap 41 is attached to the lower end opening side of the housing 1 by obtaining the connecting state of the connecting windows 11 and the connecting claws 44.

Furthermore, in such an assembled state, the pressing member 24 presses the elastic sealing member 23 and the sliding member 22 to the up stream side of the housing 1 until the flange portion 27 of the sliding member 22 touches the projecting collar 8, by the urging spring pressure of the coil spring 51, and at the same time, the tip portion of each guiding blade 26 of the sliding member 22 enters each companion guiding rib 6 to be connected, and consequently, the valve body 21 itself is slidably supported in the housing 1, in the state of being supported at both ends by the sliding touch of the guiding blades 26 bound by the guiding ribs 6 to the inner wall surface of the tank inner portion 2B, and the insertion of the axial portion 30 into the support cylindrical portion 42.

Accordingly, as shown in Fig. 4, the fuel back flow check valve arranged like this may be at the service, when the welding piece 4 of the tank outer portion 2A is welded to the side wall of the fuel tank T while making the tank inner portion 2B of the housing 1 face into the fuel tank T through an attaching hole previously pierced in the side wall of the fuel tank T made of a resin, and the lower end portion of the fuel supply pipe P is fitted to the upper end opening side of the tank outer portion 2A projecting from the fuel tank T.

Then, when the refueling is performed by using a refueling gun (not shown in the figure) from the fuel supply pipe P, the valve body 21 itself slides to the down stream side against the urging spring pressure of the coil spring 51 by the pressure of the flow of the supply fuel, as shown in Fig. 5, and widely opens the connecting hole portion 12 of the tank inner portion 2B of the housing 1, and consequently, the supply fuel is permitted to flow in the fuel tank T through each cutout hole 10.

Furthermore, at this refueling time, the sliding member 22 slides along the inner wall surface of the tank inner portion 2B of the housing 1, while making the tip portion of each guiding blade 26 of itself enter each corresponding companion guiding rib 6 to be connected, in the state where an unnecessarily turning is prevented by the guiding rib 6, and therefore, the sliding attitude is extremely stable and there is no fear to raise the flow resistance of the supply fuel, and further, the guiding blade 26 sliding to the down stream side agrees with each frame wall 9 of the tank inner portion 2B, and therefore, because of this, there is no fear to raise the flow resistance of the supply fuel. Furthermore, in the valve body 21, a stable sliding is also ensured by the above mentioned state of being supported at both ends of the up stream side and the down stream side.

Furthermore, the flowing direction of the supply fuel is controlled by the lifting shoulder portion 25 of the sliding member 22, and the supply fuel is prevented from crashing into the sealing lip portion 28 of the elastic sealing member 23 as much as possible, and consequently, especially, there is no fear that the sealing lip portion 28 of the elastic sealing member 23 is permanently deformed by fatigue in a short period.

After the refueling, this time, as shown in Fig. 6, the pressing member 24 is pressed to the up stream side by the urging spring pressure of the coil spring 51, and therefore, accompanied with this, the valve body 21 itself slides to the up stream side of the housing 1 until the flange portion 27 of the sliding member 22 touches the projecting collar 8, while holding the elastic sealing member 23 between the flange portion 32 of the pressing member 24 and the flange portion 27 of the sliding member 22 in a state of a sandwich, and makes the sealing lip portion 28 with a large diameter of the elastic sealing member 23 adhere to the projecting collar 8 from the rear of the flange portion 27 of the sliding member 22, and consequently, the connecting hole portion 12 of the tank inner portion 2B of the housing 1 is closed.

Furthermore, in such a closing state, since the sealing lip portion 28 of the elastic sealing member 23 adheres to the projecting collar 8 accompanied with a spring pressure, the connecting hole portion 12 is closed in a completely sealed state, and for example, even if the fuel supply pipe P is damaged or broken because of a crash accident or the like, the fuel in the fuel tank T can effectively be prevented from flowing back to the fuel supply pipe P side through the connecting hole portion 12 of the housing 1. Furthermore, the sealing lip portion 28 of the elastic sealing member 23 elastically adheres to the projecting collar B in a state of touching the projecting collar 8 of the flange portion 27 of the sliding member 22, and therefore, because of this point, the permanent deformation by fatigue of the sealing lip portion 28 with a large diameter of the elastic sealing member 23 can also be canceled.

Next, the fuel back flow check valve according to a second embodiment will be described. Basically, the valve of the second embodiment also follows that of the first embodiment as it is, and is different in that especially, the valve body 21 side is arranged as follows.

That is, as shown in Fig. 7A, the-second embodiment adopts such an arrangement that while the axial portion 30 inserted into and supported by the support cylindrical portion 42 af the cap 41 is directly provided onto the sliding member 22 side, the whole lengths of 4 pieces of guiding blades 26 slidingly touch the inner wall surface of the tank inner portion 2B of the housing 1, and on the other hand, while a ring-like convex portion 33 is provided on the flange portion 27 and a positioning cylindrical portion 34 with a small diameter is provided at the central portion on the down stream side of the conical shape, a through hole 35 passing through the axial portion 30 is opened at the central portion of the pressing member 24, and on the up stream side thereof, a positioning cylindrical portion 36 with a large diameter to which the positioning cylindrical portion 34 is fitted with a constant clearance, is provided.

Accordingly, in the second embodiment, when the refueling from the fuel supply pipe P is performed by using a refueling gun, the valve body 21 itself also slides to the down stream side against the urging spring pressure of the coil spring 51 by the pressure of the flow of the supply fuel (not shown in the figure specifically), and widely opens the connecting hole portion 12, and consequently, similarly to the first embodiment, the supply fuel is permitted to flow into the fuel tank T from each cutout hole 10.

However, in this case, since each guiding blade 26 of the sliding member 22 slides along the inner wall surface of the tank inner portion 2B across the whole length, the sliding attitude thereof becomes stabler, and further, the sliding member 22 itself is supported in a state of being supported at both ends by the sliding touch of the guiding blades 26 to the inner wall surface and the insertion of the axial portion 30.

into the support cylindrical portion 42, and therefore, because of this, the stable sliding attitude of the valve body itself can also more be ensured.

Furthermore, as shown in Fig. 7B, after the refueling, the valve body 21 itself slides to the' up stream side by the urging spring pressure of the coil spring 51, and makes the sealing lip portion 28 of the elastic sealing member 23 adhere to the projecting collar 8, and consequently, the connecting hole portion 12 is closed. In such a state, in addition to the adhering of the sealing lip portion 28 of the elastic sealing member 23 to the projecting collar 8 accompanied with a spring pressure, the convex portion 33 provided at the flange portion 27 of the sliding member 22 also adheres to the projecting collar 8 accompanied with a spring pressure, and the connecting hole portion 12 is sealed in a state of double adhering, so that the sealing ability may be improved strikingly. Accordingly, the fuel in the fuel tank T can more effectively be prevented from flowing back to the fuel supply pipe P side.

Furthermore, it becomes possible by the action of the positioning cylindrical portions 34 and 36 that the centering of the sliding member 22 and the pressing member 24 is performed and the elastic sealing member 23 is held between at a correct position at all times, and therefore, the assembling ability of the valve body 21 itself becomes better, of course, and further, it can also additionally be ensured to make the sealing lip portion 28 of the elastic sealing member 23 surely adhere to the projecting collar 8.

Referring now to Figs. 8A,8B and 8C, the fuel back flow check valve according to a third embodiment will be described.

Basically, the valve of the second embodiment also follows that of the second embodiment as it is, and is different in that especially, the axial portion 30 of the sliding member 22 is removed. The fuel back flow check valve according to the third embodiment is improved for the purpose that the check valve according to the present invention can be used and operated even in a small-sized auxiliary tank or in a tank which is provided with a baffle eliminating fuel wave and noise.

Accordingly, in the third embodiment, when the refueling from the fuel supply pipe P is performed by using a refueling gun, the valve body 21 itself also slides to the down stream side against the urging spring pressure of the coil spring 51 by the pressure of the flow of the supply fuel (not shown in the figure specifically), and widely is opening the connecting hole portion 12 as shown in Fig. 8B. In this stage, since each guiding blade 26 of the sliding member 22 slides along the inner wall surface of the tank inner portion 2B across the whole length, the sliding attitude thereof becomes stabler, and further, the sliding member 22 itself is supported in a state of being supported at both ends by the sliding touch of the guiding blades 26 to the inner wall surface and the an upper portion of the support cylindrical portion 42 into the through hole 35 as shown in Fig. 8B.

Consequently, similarly to the stage described above, at a stage where the refueling from the fuel supply pipe P is further performed by using a refueling gun with more high pressure, the valve body 21 itself also slides to the bottom end of the stroke against the urging spring pressure of the coil spring 51, and the connecting hole portion 12 is completely opened as shown in Fig. 8C, then the supply fuel is permitted to flow into the fuel tank T from each cutout hole 10. In this stage, since each guiding blade 26 of the sliding member 22 slides along the inner wall surface of the tank inner portion 2B across the whole length, the sliding attitude thereof becomes stabler, and further, the sliding member 22 itself is supported in a state of being supported at both ends by the sliding touch of the guiding blades 26 to the inner wall surface and the insertion of the support cylindrical portion 42 into the through hole 35, and therefore, because of this, the stable sliding attitude of the valve body itself can also more be ensured.

Furthermore, since the axial portion 30 of the sliding member 22 is removed, the fuel back flow check valve according to the third embodiment can be used and applicable even in the small-sized auxiliary tank or in the tank which is provided with the baffle, without any jamming between the axial portion 30 and the baffle or walls of the small-sized auxiliary tank.

While preferred embodiments 'of the present invention have been described using specific terms, such description is for illustrative purposes, and it is to be understood that changes

Claims

CLAIMS:

1. A check valve to be mounted at a connecting hole portion between a fuel tank and a fuel supply pipe, comprising: a sliding type valve body to open and close the connecting hole portion, wherein the valve body is provided with a plurality of guiding projections extending on the upstream side of the connecting hole portion; and the guiding projections slidingly contact to an inner wall surface constituting the upstream side of the connecting hole portion.

2. A check valve according to claim 1, wherein the valve body comprises an axial portion extending on the downstream side of the connecting hole portion; and the axial portion is slidably supported.

3. A check valve according to claim 1 or 2, wherein the valve body comprises: a shoulder portion formed onto the peripheral portion of the valve body for regulating the flowing direction of the supplied fuel; a flange portion which touches a fringe of the connecting hole portion and which is formed on the downstream side of the valve body; and an elastic sealing portion with a diameter larger than that of the flange portion sealingly engageable with the fringe of the connecting hole portion from the downstream; side of the flange portion.

4. A check valve according to claim 1, 2 or 3, further comprising: fuel passing cut out holes located on the downstream side of the connecting hole portion, the fuel passing cutout holes being framed by a plurality of frame walls; and valve body rotation preventing members for positioning the guide projections and the frame walls at aligned positions.

5. A check valve according to claim 1, further comprising: a cap formed with a support cylindrical portion wherein the valve body is also guidedly supported by the support cylindrical portion through a hole formed at a downstream side portion of the valve body at a position where the valve body opens the connecting hole portion.

6. A check valve to be mounted at a connecting hole portion between a fuel tank and a fuel supply pipe, comprising: a sliding type valve body to open and close the connecting hole portion, wherein the valve body comprises: a sliding member which is provided with a plurality of guiding projections extends on the upstream side of the connecting hole portion; an elastic sealing member sealingly engageable with a fringe of the connecting hole portion; and a pressing member for pressing the elastic sealing member to the sliding member side.

7. A check valve according to claim 6, further comprising: fuel passing cutout holes located on the downstream side of the connecting hole portion, the fuel passing cutout holes being framed by a plurality of frame walls; and valve body rotation preventing members positioning the guide projections and the frame walls at aligned positions.

8. A check valve according to claim 6, further comprising: a cap formed with a support cylindrical portion, wherein the valve body is guidingly supported by an inner wall surface of the connecting hole portion through the guiding projections and supported by the support cylindrical portion through a hole formed at a downstream side portion of the valve body at a position where the valve body opens the connecting hole portion.

9. A check valve for a fuel supply to a fuel tank, said check valve comprising a housing having an inlet connectable to a fuel supply pipe and an outlet for discharging fuel supplied to said inlet into a fuel tank, and a valve body guided for sliding movement in said housing between a first position in which backs low from the outlet to the inlet is prevented and a second position in which flow from the inlet to the outlet is allowed, the valve body being biased into said first position and slidable therefrom to the second position against said bias by a predetermined pressure of fuel flow during a refuelling operation.

10. A check valve as claimed in claim 9, wherein said body obturates a flow passage between said inlet and outlet when in said first position.

11. A check valve as claimed in claim 10 wherein said body comprises guide means cooperable with surface means of said housing upstream of said flow passage.

12. A check valve as claimed in claim 11, wherein said body, or a part cooperable therewith, comprises further guide means whicb are slidably guided downstream of said flow passage.

13. A check valve as claimed in claim 10 or 11, wherein said guide means and cooperable surface means are such as to allow movement of the body along an axis whilst preventing rotation of the body about that axis.

14. A check valve as claimed in any one of claims 10 to 13 wherein said outlet comprises a plurality of the holes circumferentially spaced apart in an annular portion of said housing downstream of said flow passage.

15. A check valve substantially as hereinbefore described with reference to Figures 1 to 6 or 7A and B or 8A, B and C of the accompanying drawings.