JP2008151243A - Relief valve - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a relief valve adapted to have sufficient sealability even when force for pressing a valve element to a valve seat is small. <P>SOLUTION: The relief valve is disposed in a discharge passage of fuel vapor for discharging the fuel vapor in a fuel tank to the discharge passage when pressure in the fuel tank exceeds a predetermined value. The relief valve comprises a valve element housing part 70, an opening portion 74 formed in the valve element housing part 70, the valve element 80 for opening and closing the opening potion 74 and a spring 95 for pressing the valve element 80 and biasing it to normally close the opening portion 74. The valve seat 90 molded separately from the valve element housing part 70 is attached to the opening portion 74, the valve seat 90 has a tube portion 91 inserted in an inner periphery of the opening portion 74 and a flange portion 93 contacting with an outer or inner circumference of the opening portion 74, and a surface of the valve seat 90 contacting with the valve element 80 is formed so that flatness is 0.02 mm or less and the maximum height Ry of surface roughness is 1 μm or less. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is arranged in the fuel vapor discharge passage, and adjusts the pressure in the fuel tank by discharging the fuel vapor in the fuel tank to the discharge passage when the pressure in the fuel tank exceeds a predetermined value. A relief valve that can be used.

  Generally, the fuel tank is provided with a relief valve for adjusting the pressure in the fuel tank by discharging the fuel vapor to the canister when the pressure in the fuel tank increases to a predetermined value or more. As such a relief valve, generally used is a structure in which a valve body made of rubber or the like is pressed against an opening for communicating the fuel vapor discharge passage and the inside of the fuel tank by an elastic biasing means such as a spring. Has been.

  On the other hand, in the following Patent Document 1, a bottomed cylindrical shape is provided, a main body provided with a communication path at the bottom, a valve seat disposed at the bottom of the main body, and a valve seat arranged so as to be able to contact and separate. A relief valve comprising a valve body (poppet), a spring that presses the valve body against the valve seat side, and an adjustment screw that is attached to the opening side of the main body and adjusts the biasing force of the spring is disclosed. ing. In addition, a seal body molded separately from the valve seat is fixed to the outer periphery of the valve seat and the contact surface with the valve body, so that the valve body abuts through the seal body. It has become.

Then, when the pressure of the fluid flowing into the main body rises above a predetermined value from the communication passage provided at the bottom of the main body, the valve body slides against the urging force of the spring, and the seal fixed to the valve seat The pressure can be adjusted by allowing the fluid to escape from the gap formed between the body and the valve body.
Japanese Utility Model Publication No. 62-102073

In general, in a relief valve, when the fluid pressure is below a predetermined value, there is a gap between the valve body and the valve seat, so that the fluid does not leak from there. A high sealing performance is required between them.
In this case, if an elastic member is used for at least one of the contact surfaces of the valve body and the valve seat, the elastic member is compressed by the pressing force of the spring and the gap is eliminated, so that the sealing performance can be improved. Immediately before the pressure is applied, the pressure of the spring and the pressure of the fluid are balanced, and the force that presses the valve body against the valve seat is reduced.Therefore, the elastic member is not compressed and it is difficult to ensure the sealing performance. there were.

  In addition, the relief valve of the fuel tank needs to be designed compactly because of low valve opening pressure and space requirements, and since the diameter of the opening is limited, only a spring with a small spring force can be placed There are many. As a result, since the force for pressing the valve body against the valve seat becomes small, there is a problem that the sealing performance cannot be sufficiently improved even if an elastic member is used.

  Even in the relief valve described in Patent Document 1, the sealing performance is enhanced by fixing a seal body molded separately from the valve seat to the outer periphery of the valve seat and the contact surface with the valve body. As described above, there has been a problem that sufficient sealing performance cannot be obtained when the force pressing the valve body against the valve seat becomes small.

  Accordingly, an object of the present invention is to provide a relief valve that can obtain a sufficient sealing performance even when the force for pressing the valve body against the valve seat is small.

In order to achieve the above object, a first aspect of the present invention is arranged in a fuel vapor discharge passage for communicating between a fuel tank and a canister arranged outside the fuel tank, and the pressure in the fuel tank is In the relief valve that discharges the fuel vapor in the fuel tank to the discharge passage when it becomes a predetermined value or more,
A valve body accommodating portion provided in the discharge passage; an opening for communicating the inside of the fuel tank formed at one end of the valve body housing portion with the discharge passage; and opening and closing the opening. Similarly to the valve body slidably disposed in the valve body housing portion, the valve body is also disposed in the valve body housing portion, and presses the valve body toward the opening portion, and is elastically biased so as to always close the opening portion And a spring to
A valve seat molded separately from the valve body housing portion is attached to the opening, and the valve seat comes into contact with the valve body to close the opening,
The valve seat has a cylinder part inserted into the inner periphery of the opening part, and a flange part formed on the outer periphery of the cylinder part and in contact with the outer periphery or the inner periphery of the opening part,
A relief valve characterized in that the surface of the valve seat that contacts the valve body is formed so that the flatness is 0.02 mm or less and the maximum height Ry of the surface roughness is 1 μm or less. Is to provide.

  According to the above invention, when the pressure in the fuel tank increases, the valve body slides against the urging force of the spring and moves away from the valve seat. As a result, the opening is opened. Flows into the discharge passage from the opening and is sent to the canister disposed outside through the discharge passage. For this reason, it can suppress that the pressure in a fuel tank becomes more than predetermined value, and can prevent the burst by the internal pressure rise of a fuel tank, etc.

  The valve seat that is molded and attached to the opening separately from the valve body housing part has a flatness of 0.02 mm or less on the surface that contacts the valve body and the maximum height of the surface roughness. Since Ry is formed to be 1 μm or less, it has a smooth surface with high flatness and little unevenness. For this reason, the adhesiveness between the valve body and the valve seat is improved, and a good sealing property can be obtained even when the pressing force by the spring cannot be sufficiently obtained.

  Further, since the valve seat is molded separately from the valve body housing portion, the valve seat can be formed in a relatively simple shape as compared with the case of being molded integrally with the valve body housing portion, and the surface accuracy is improved. Therefore, the flatness and the surface roughness as described above can be easily obtained.

  According to a second aspect of the present invention, in the first aspect, the flange portion of the valve seat abuts on the inner side of the opening portion, and the flange portion has a predetermined length toward the opposite side to the cylindrical portion. The flange portion of the valve seat is formed integrally with a guide wall portion having an inner diameter that matches the outer diameter of the valve body, and abuts on the inner side of the opening portion, and on the periphery of the flange portion. Provides a relief valve that extends in a predetermined length toward the opposite side of the cylindrical portion and is integrally formed with a guide wall portion having an inner diameter that matches the outer diameter of the valve body. .

  According to the above invention, since the guide wall is integrally formed on the periphery of the flange portion of the valve seat, the guide wall smoothly slides when the valve body slides away from the valve seat. When the valve body comes into contact with the valve seat, the valve body is brought into contact with the valve seat in a stable posture without tilting, and the sealing performance between the valve body and the valve seat is improved. Further improvement can be achieved.

  According to the relief valve of the present invention, the surface of the valve seat that contacts the valve body is formed so that the flatness is 0.02 mm or less and the maximum height Ry of the surface roughness is 1 μm or less. Therefore, the flatness is high and the surface is smooth with little unevenness, the adhesion between the valve body and the valve seat is enhanced, and a good sealing property can be obtained even when the pressing force by the spring cannot be obtained sufficiently. In addition, since the valve seat is formed separately from the valve body housing portion, it can be formed in a relatively simple shape, so that the flatness and surface roughness as described above can be easily obtained.

  Hereinafter, with reference to FIGS. 1-7, one Embodiment of the relief valve of this invention is described.

  In the case of this embodiment, the relief valve according to the present invention is a valve device 10 provided with a cut valve for preventing the fuel in the fuel tank from leaking to the outside when the vehicle turns or greatly tilts. Are integrally provided.

  1 to 3, the valve device 10 includes a case body 20 that slidably accommodates the float valve 40, a lower cap 30 that is attached to a lower opening of the case body 20, and a case body. 20 and an upper cap 50 mounted on the upper side of the case body 20, and further, a valve body housing portion 70 for slidably housing the valve body 80 is formed on the upper side of the case body 20. A valve seat 90 that is separate from the valve body housing portion 70 is attached to an opening 74 formed at one end of the valve body housing portion 70.

  The case body 20 includes a cylindrical peripheral wall 21 and an upper wall 23 that closes the upper surface thereof, and a communication hole 25 passes through the center of the upper wall 23. A plurality of through holes 21a serving as passages for fuel and fuel vapor are formed in the peripheral wall 21, and a claw portion 21b that engages with an engagement hole 33a of the lower cap 30 described below is provided below the peripheral wall 21. A plurality are formed along the circumferential direction.

  Similar to the peripheral wall 21 of the case body 20, the lower cap 30 attached to the lower opening of the case body 20 has a circular bottom plate 31 in which a through hole 31 a that allows fuel to pass is formed, and the bottom plate 31. The cover wall 33 is erected from the peripheral edge and covers the lower outer periphery of the peripheral wall 21 of the case body 20. A support protrusion 34 is formed in the center of the bottom plate 31 to stably support one end of the float valve spring 45. Further, the cover wall 33 is formed with an engagement hole 33a that engages with a claw portion 21b formed on the peripheral wall 21 of the case main body 20, whereby the lower cap 30 is attached to the lower opening of the case main body 20. Is done.

  Further, a standing wall 35 that rises upward is formed at one location on the outer periphery of the cover wall 33, and a stopper wall 37 that has a through hole 37 a for allowing fuel to pass through protrudes from the upper outside of the standing wall 35. Yes. As shown in FIG. 3, when the lower cap 30 is attached to the case main body 20, the stopper wall 37 has a flange portion 93 (described later) of the valve seat 90 attached to the opening 74 of the valve body housing portion 70. The flange portion 93 of the valve seat 90 is sandwiched between the stopper wall 37 and the bottom wall 73 of the valve body housing portion 70, and the valve seat 90 is inserted into the opening 74. It is designed to be secured. The stopper wall 37 also serves to prevent foreign matter from entering the opening 74.

  The float valve 40 accommodated in the case body 20 has a substantially cylindrical shape, and a valve head 41 projects from the center of the upper surface. The valve head 41 contacts and separates from the communication hole 25 formed in the case body 20. It is supposed to be. In addition, a plurality of ribs 43 are formed on the outer periphery of the float valve 40 so as to extend vertically at equal intervals along the circumferential direction. The ribs 43 are in sliding contact with the inner periphery of the peripheral wall 21 of the case body 20. The up / down sliding operation is guided.

  Then, the float valve 40 is accommodated in the case body 20 with the float valve spring 45 inserted into the recess 44 provided at a predetermined height from the bottom surface of the float valve 40, and then the lower cap 30. The lower cap 30 is mounted below the case body 20 by engaging the claw portions 21b formed on the lower outer periphery of the peripheral wall 21 with the engagement holes 33a. In this way, the float valve spring 45 is provided between the float valve 40 and the bottom plate 31 of the lower cap 30 and applies an upward biasing force to the float valve 40.

  Further, when the float valve 40 is not immersed in fuel, the float valve spring 45 is compressed by its own weight and is placed on the bottom plate 31 of the lower cap 30. When the fuel rises due to the inclination of the vehicle and the float valve 40 is immersed in the fuel, the float valve 40 is lifted by the buoyancy and the urging force of the float valve spring 45, and the valve head 41 is placed in the case. As shown in FIG. 5, the communication hole 25 is closed by contacting the lower inner periphery of the communication hole 25 of the main body 20. The part demonstrated above comprises the cut valve of the valve apparatus 10 in this embodiment.

  Further, a bracket 60 is provided above the upper wall 23 of the case body 20 so as to be fixed to the fixing bracket 5 fixed in the fuel tank 1 to fix the valve device 10 in the fuel tank. . The bracket 60 has a frame-shaped outer wall portion 61 erected from the upper surface of the upper wall 23 of the case body 20. As shown in FIG. 1, the outer wall portion 61 extends long in one direction, and a front portion thereof protrudes outward from the case body 20. Further, a flange portion 63 extends from the upper wall of the outer wall portion 61 to the rear from the middle portion, and a predetermined gap is provided from the upper wall 23 in parallel. A rear end portion of the flange portion 63 The engaging claw 65 extends outward from the case body 20.

  Then, as shown in FIG. 1, the bracket 60 is inserted into a U-shaped cutout portion 7 a formed on the bottom plate 7 of the fixture 5, thereby fixing the fixture 5 in the gap between the flange 63 and the upper wall 23. And the flange 63 engages with the peripheral edge of the notch 7 a, and the engaging claw 65 engages with one side of the rear of the bottom plate 7. Is designed to be secured.

  As described above, the front portion of the outer wall portion 61 of the bracket 60 protrudes outward from the case body 20, but the frame-like valve body housing portion 70 is formed below the front portion of the outer wall portion 61. Is provided. This valve body accommodating part 70 becomes a part which comprises the relief valve of this invention. And in this valve body accommodating part 70, the valve body 80 which consists of the slide cylinder 81 and the sealing member 85 is arrange | positioned so that a slide is possible, and this valve body 80 is pressed toward the opening part 74, and the opening part 74 is always used. A spring 95 that is elastically biased so as to be closed is accommodated, and a relief valve is configured to perform a function of discharging fuel vapor out of the fuel tank when the pressure in the fuel tank increases to a predetermined value or more. .

  2 to 4, the valve body accommodating portion 70 is formed on a pair of side walls 71, 71 extending in parallel with each other from below the front portion of the outer wall portion 61, and on one side portion of each of the side walls 71, 71. It has a substantially rectangular tube shape surrounded by a connected front wall 72 and a bottom wall 73 connected below the pair of side walls 71, 71. Further, the other side portions of the side walls 71 and 71 are connected to the front surface of the peripheral wall 21 of the case main body 20, the back side of the valve body housing portion 70 is closed, and the upper opening thereof is an upper cap 50 described later. It is obstructed by the front part.

  In addition, a circular opening 74 is formed at the center of the bottom wall 73, and a valve seat 90 described later is attached to the opening 74, and a seal member 85 constituting the valve body 80 serves as the valve seat 90. The opening 74 is opened and closed in contact with and away from the opening. The valve body 80 and the valve seat 90 will be described in detail later.

  2 and 3, the upper portion on the back side of the valve body housing portion 70 communicates with a space surrounded by the upper wall 23, the frame-like wall 67, and the upper cap 50, and the inflow port 75. Is formed. As shown in FIG. 2, when the buoyancy due to fuel does not act on the float valve 40 and the communication hole 25 above the case body 20 is open, the inflow port 75 passes through the communication hole 25 and the upper wall 23. This is a portion for introducing the fuel vapor flowing in the space surrounded by the frame-shaped wall 67 and the upper cap 50 into the valve body housing portion 70. A circular outlet 76 is formed in the middle of the front wall 72 in the height direction, and a connecting pipe 77 is integrally projected from the periphery of the outlet 76. The outlet 76 is a portion for sending the fuel vapor in the valve body accommodating portion 70 to the connecting pipe 77, while the connecting pipe 77 is connected to a pipe connected to a canister (not shown) on its outer periphery, 1 constitutes a part of a fuel vapor discharge passage for communicating the inside and outside of 1.

  Furthermore, a plurality of guide ribs 78 extending in the vertical direction are formed inside the valve body housing portion 70 along the circumferential direction (see FIGS. 1 and 4). More specifically, there is an angular rib 78a having a triangular cross-section that gradually becomes narrower from the inside of the four corners of each wall portion constituting the valve body housing portion 70 toward the center of the valve body housing portion 70. Between the square ribs 78a formed and excluding the front wall 72, intermediate ribs 78b having a triangular cross-section are protruded at a height lower than that of the square ribs 78a. These ribs guide the sliding operation of the cylindrical slide cylinder 81 constituting the valve body 80, and a gap is formed between the outer periphery of the slide cylinder 81 and the inner periphery of the valve body accommodating portion 70, When the valve body 80 is opened from the opening 74, the fuel vapor is passed therethrough. A guide projection 83a of a slide cylinder 81, which will be described later, is fitted between the square ribs 78a, 78a on both sides of the inner periphery of the front wall 72, thereby restricting rotation during sliding movement of the slide cylinder 81.

  A frame-like wall 67 is formed inside the outer wall portion 61 of the bracket 60 so as to be concentric with the outer wall portion 61. The communication hole 25 formed in the upper wall 23 described above is located inside the rear end portion of the frame-like wall 67, and the inside of the case body 20 and the inside of the frame-like wall 67 are in communication with each other. Yes. Further, the inner side of the front portion of the frame-shaped wall 67 is connected to the peripheral edge of the upper opening of the valve body housing part 70, and a guide rib 78 formed on the inner periphery of the valve body housing part 70 is provided on the inner periphery thereof. Further, the internal space of the frame-shaped wall 67 and the internal space of the valve body accommodating portion 70 are in communication with each other.

  A valve body 80 and a spring 95 that presses the valve body 80 are housed in the valve body housing portion 70. In this state, the upper cap 50 is attached to the upper opening of the bracket 60 provided above the case body 20. The The upper cap 50 includes a ceiling plate 51 having a shape that matches the outer shape of the outer wall portion 61 of the bracket 60, and an outer peripheral rib that extends from below the ceiling plate 51 so as to match the inner periphery of the outer wall portion 61. 53, and is attached to the upper opening of the bracket 60 by an adhering means such as ultrasonic welding or hot plate welding.

  Although the bracket 60 is closed by the upper cap 50, as described above, the internal space of the frame-shaped wall 67 communicates with the internal space of the valve body housing portion 70, and thus the communication hole 25 of the upper wall 23. The fuel vapor that has flowed from the air passes through the space surrounded by the upper wall 23, the frame-like wall 67, and the upper cap 50, and flows into the valve body housing portion 70.

  Further, a columnar support protrusion 55 projects from the front lower surface of the ceiling plate 51 of the upper cap 50. The support protrusion 55 is inserted into the inner periphery of the spring 95 when the upper cap 50 is attached to the bracket 60, and supports the inner periphery of the spring 95 with the outer peripheral surface thereof. One end of the spring 95 comes into contact with the lower surface of the ceiling plate 51 to support the spring 95.

  The valve body 80 is slidably accommodated in the valve body accommodating portion 70 described above. The valve body 80 in this embodiment includes a substantially cylindrical slide cylinder 81 and a seal member 85 attached to one end of the slide cylinder 81. As shown in FIGS. 1 and 3, the slide cylinder 81 includes a circular bottom wall 82 that supports the other end of the spring 95, and a cylinder wall 83 that extends from the periphery of the bottom wall 82 by a predetermined length, In the middle of the cylindrical wall 83 in the length direction, a pair of through holes 84 and 84 are formed to face each other, and further, in the center of the bottom wall 82 is a shaft hole into which the shaft portion 87 of the seal member 85 is inserted. 82a is formed. In addition, a guide protrusion 83a is formed on the outer periphery of the upper end portion of the cylindrical wall 83 to be fitted between the square ribs 78a and 78a on the front wall 72 side shown in FIG. In addition, an inclination preventing small projection 83b narrower than the guide projection 83a is provided on the outer periphery of the lower end portion of the cylindrical wall 83, and abuts against the lower inner surface of the front wall 72 (see FIG. 2). It serves to prevent the tilt of 81.

  On the other hand, a seal member 85 attached to the slide cylinder 81 includes a thin disc-shaped flange portion 86, a shaft portion 87 extending from the center of the flange portion 86 by a predetermined length, and in the middle of the shaft portion 87 in the axial direction. It is formed from a retaining projection 88 that is enlarged by a predetermined diameter. Then, from the outside of the bottom wall 73 of the valve body housing portion 70, the shaft portion 87 is inserted into the shaft hole 82a and pulled out from the opposite side, thereby contacting the outer surface of the flange portion 86 bottom wall 82 and the bottom wall 82. A retaining protrusion 88 abuts on the inner surface of the sliding cylinder 81, and the sealing member 85 can be prevented from being attached to the bottom wall 82 of the slide cylinder 81 without being loosely attached. As the material of the sealing member 85, rubber materials such as fluorine-based rubber, fluorosilicone rubber, H-NBR (hydrogenated nitrile rubber), NBR (nitrile rubber) are preferably used.

  In this embodiment, the valve body 80 includes the slide cylinder 81 and the seal member 85. However, the spring 95 is directly brought into contact with the disc-shaped seal member without providing the slide cylinder 81. This may be a valve body and is not particularly limited.

  Further, in the valve device 10 described above, the portions excluding the springs 45 and 95 and the seal member 85 of the valve body 80 are made of, for example, aromatic nylon, polyoxymethylene (POM), polyphenylene sulfide (PPS), or the like. It is made of synthetic resin material.

  The valve body 80 is housed and disposed in the valve body housing portion 70 with the seal member 85 attached to one end of the slide cylinder 81. At this time, the seal member 85 of the valve body 80 is placed in the opening 74. Instead of contacting directly, the valve seat 90 attached to the opening 74 is contacted. The relief valve according to the present invention is characterized in that the valve seat 90 is formed separately from the valve body housing portion 70 and the surface accuracy of the surface in contact with the valve body 80 is set to a predetermined value. .

  Referring to the partially enlarged view shown in FIG. 1, the valve seat 90 has a through hole 92 and a cylindrical tube portion 91 inserted into the inner periphery of the opening 74, and the tube portion 91. The flange portion 93 is formed so as to expand in an annular shape from the outer periphery of the base end portion and engages with the outer peripheral edge of the opening 74. In the case of this embodiment, the cylindrical portion 91 has an outer diameter that is the same as or slightly larger than the inner diameter of the opening 74, and the cylindrical portion 91 is press-fitted into the opening 74. ing. Moreover, the height of the cylinder part 91 is formed so as to be higher than the plate thickness of the bottom wall 73 of the valve body housing part 70, and as shown in FIG. When attached, it protrudes from the inner surface of the bottom wall 73.

  And while aligning the front-end | tip part of the cylinder part 91 with the opening part 74 and pushing the valve seat 90 from the outer side of the opening part 74, the cylinder part 91 is press-fitted in the inner periphery of the opening part 74, and the valve seat 90 is still inserted. When pushed in, the flange portion 93 abuts against the outer peripheral edge of the opening portion 74 and further pressing is restricted, and the flange portion 93 engages with the outer peripheral edge of the opening portion 74, and the valve seat 90 is inserted into the opening portion 74. Can be installed.

  In addition, the valve seat 90 in this embodiment is formed of a synthetic resin material such as polyoxymethylene (POM), as in each part of the valve device 10, but in some cases, a metal such as stainless steel or the sealing member A rubber material such as fluorinated rubber similar to 85 may be used.

  Furthermore, in this embodiment, the valve seat 90 is attached by press-fitting the cylindrical portion 91 into the opening 74, but it may be attached by other methods. For example, the valve seat 90 may be attached by applying an adhesive to the outer periphery of the cylindrical portion 91 and / or the inner periphery of the opening 74 and bonding the portions to each other, or ultrasonic welding, spin welding, laser The valve seat 90 may be attached to the opening 74 by welding the outer periphery of the cylindrical portion 91 and the inner periphery of the opening 74, the periphery of the flange portion 93 and the opening 74, or the like by welding means such as welding. Further, at least the cylindrical portion 91 of the valve seat 90 is formed of a rubber material, and the outer periphery of the cylindrical portion 91 is formed slightly larger than the inner periphery of the opening 74, and the outer periphery of the cylindrical portion 91 is formed of a rubber material. The valve seat 90 may be attached to the opening 74 by being elastically pressed against the inner periphery of the opening 74 by the elastic force. Further, the valve seat 90 is attached to the opening 74 by screwing a female screw on the inner periphery of the opening 74 and screwing a male screw on the outer periphery of the cylindrical portion 91 and screwing them together. Also good. Further, the valve seat 90 may be integrally attached to the opening 74 by insert-molding the valve seat 90 in the valve body accommodating portion 70.

  As described above, the valve seat 90 attached to the opening 74 is configured such that the distal end surface of the cylindrical portion 91 protrudes from the inner end surface of the bottom wall 73 as shown in FIG. The flange portion 86 of the sealing member 85 of the valve body 80 abuts on the projecting end surface of the cylindrical portion 91, thereby closing the through hole 92 in the cylindrical portion 91 and closing the opening 74. ing.

  In the present invention, as described above, the surface accuracy of the surface of the valve seat 90 that contacts the valve body 80 (hereinafter referred to as “valve seat contact surface”) is defined by a predetermined value. It is one of the features. That is, in this embodiment, it is formed so that the flatness of the distal end surface of the cylindrical portion 91 that is the valve seat contact surface is 0.02 mm or less and the maximum height Ry of the surface roughness is 1 μm or less. ing. Thus, since the surface accuracy of the valve seat contact surface is defined, the valve seat contact surface can be a smooth surface with high flatness, less unevenness, and the valve body when the valve body is closed. The sealing performance between 80 and the valve seat 90 can be improved.

  The reference length when measuring the maximum height Ry of the surface roughness of the valve seat contact surface is 0.8 mm.

  Here, the surface roughness Ry of the valve seat abutting surface is set to 1 μm or less. If the surface roughness Ry is larger than 1 μm, the unevenness of the valve seat abutting surface becomes large, and the valve body 80 This is because sufficient adhesion to the film cannot be obtained. On the other hand, the flatness of the valve seat abutment surface is set to 0.02 mm or less. If the flatness is greater than 0.02 mm, a portion that is not in close contact with the abutment surface between the valve body 80 and the valve seat 90 occurs. This is because a gap is generated and the sealing performance is lowered. Further, depending on the elastic biasing force of the spring 95 that presses the valve body 80, the amount of bending of the flange portion 86 of the seal member 85 is reduced, and as a result, the sealing performance between the valve seat contact surface and the valve body 80 is sufficiently increased. However, in the present invention, the flatness and the surface roughness of the valve seat abutting surface are set as described above, so that even if the elastic biasing force of the spring 95 is small, the valve body 80 can be firmly brought into contact with the valve seat abutment surface to ensure a sufficient sealing performance.

  Further, as shown in FIG. 3, the spring 95 has one end supported on the lower surface of the front portion of the ceiling plate 51 of the upper cap 50 and the other end supported on the inner surface of the bottom wall 82 of the slide cylinder 81. It is made to hold | maintain in the state compressed by the inside of the valve body accommodating part 70. Accordingly, the valve body 80 is elastically biased so as to press the seal member 85 toward the opening 74, and the flange portion 86 of the seal member 85 of the valve body 80 projects from the inner periphery of the opening 74. The opening 74 is in contact with the distal end surface of the cylindrical portion 91 of the valve seat 90 and is closed. When the pressure in the fuel tank 1 increases to a predetermined value or more, the seal member 85 of the valve body 80 is pressed from the outside, and the valve body 80 slides upward against the urging force of the spring 95 to open the opening. The part 74 is opened.

  Next, the operation of the valve device 10 having the above configuration will be described with reference to FIGS.

  As described above, the valve device 10 is fixed to the upper side of the fuel tank 1 via the fixing bracket 5.

  As shown in FIG. 2, when the vehicle does not shake, the liquid level of the fuel F in the fuel tank 1 does not tilt, and the float valve 40 is not immersed in the fuel, the float valve 40 is floated by the weight of the float valve 40. The valve spring 45 is compressed, the valve head 41 of the float valve 40 is separated from the communication hole 25, and the communication hole 25 is opened. In this state, when the pressure in the fuel tank 1 increases due to traveling of the vehicle or the like and fuel vapor is generated, the fuel vapor is transferred from the communication hole 25 to the upper wall 23, the frame wall 67 and the upper cap 50. Through the enclosed space, it flows into the inside of the valve body housing part 70 from the inflow port 75, passes through the clearance between the inner periphery of the valve body housing part 70 and the slide cylinder 81, and the connection pipe from the outflow port 76. 77, introduced into a canister (not shown), and discharged to the outside of the fuel tank 1.

  In the above state, when the vehicle turns or greatly tilts and the liquid level of the fuel F rises and the fuel is immersed in the float valve 40 by a predetermined height or more, buoyancy acts on the float valve 40 and the float valve Due to the urging force of the spring 45, the float valve 40 is lifted, and the valve head 41 comes into contact with the lower inner periphery of the communication hole 25 to close the communication hole 25 as shown in FIG. As a result, the fuel F is prevented from flowing into the space surrounded by the upper wall 23, the frame-shaped wall 67 and the upper cap 50 through the communication hole 25, and the fuel to the outside of the fuel tank 1 is prevented. F leakage can be reliably prevented.

  There is a case where the pressure in the fuel tank 1 still increases with the liquid level of the fuel F rising and the communication hole 25 being closed by the float valve 40. The relief valve of the present invention provided in the valve device 10 of this embodiment functions in such a case. That is, in the state shown in FIG. 5, when the pressure in the fuel tank 1 further increases to a predetermined value or more, it contacts the valve seat 90 projecting from the inner periphery of the opening 74 of the valve body accommodating portion 70, and the opening The seal member 85 of the valve body 80 that closes 74 is pressed by the fuel vapor, and the valve body 80 slides upward against the biasing force of the spring 95. As a result, the seal member 85 of the valve body 80 The through hole 92 in the cylindrical portion 91 is opened away from the distal end surface of the cylindrical portion 91 of the seat 90, and the opening 74 is accordingly opened.

  Then, the fuel vapor flowing in from the opening 74 passes through a gap between the outer periphery of the slide cylinder 81 of the valve body 80 and the inner periphery of the valve body housing portion 70, which is provided by the guide rib 78 on the inner periphery of the valve body housing portion 70. And flows in the valve body accommodating portion 70. Since a through hole 84 is formed in the cylinder wall 83 of the slide cylinder 81, a part of the fuel vapor flows through the valve hole 70 through the through hole 84. Then, the fuel vapor that has flowed through the valve body accommodating portion 70 is sent from an outlet 76 formed in the front wall 72 to a connecting pipe 77 that is a part of the discharge passage, and then sent to a canister (not shown). The fuel tank 1 is discharged to the outside. As a result, it is possible to suppress the pressure in the fuel tank 1 from exceeding a predetermined value, and to prevent rupture due to an increase in the internal pressure of the fuel tank 1.

  And in the relief valve of this invention, the surface (valve seat contact surface) which contact | abuts the valve body 80 of the valve seat 90 formed separately from the valve body accommodating part 70 has a flatness of 0.02 mm or less. In addition, since the maximum height Ry of the surface roughness is 1 μm or less, the surface is microscopically smooth and macroscopically distorted, and the valve body 80 and the valve seat 90 It is possible to improve the sealing property by improving the adhesion.

  Further, the valve seat 90 is molded separately from the valve body housing portion 70 and attached to the valve body housing portion 70, so that the shape is compared with the case where it is molded integrally with the valve body housing portion 70. Therefore, the flatness and surface roughness as described above can be easily manufactured.

  8 to 10 show another embodiment of the relief valve of the present invention. Note that substantially the same parts as those of the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

  This embodiment also has a mode in which a relief valve is integrally provided in the valve device 10 provided with a cut valve, as in the case of the above embodiment. The shape of the valve body accommodating portion 70 is different. Further, the valve seat 90 of the above embodiment is attached from the outside of the opening portion 74, whereas the valve seat 90a of this embodiment is inserted from the upper opening portion of the valve body housing portion 70, and from the inside of the opening portion 74. It is designed to be installed.

  That is, the valve seat 90a in this embodiment is formed so as to expand in a shape that fits the cylindrical tube portion 91 having the through-hole 92 and the base portion outer periphery of the tube portion 91 to the inner periphery of the valve body housing portion 70. And has a flange portion 93 that abuts on the inner periphery of the opening 74, and further extends to the periphery of the flange portion 93 in a substantially rectangular tube shape toward the side opposite to the tube portion 91. The guide wall portion 94 is integrally formed.

  Further, as shown in FIG. 9, the guide wall portion 94 has an upper wall of the case body 20 in a state where the tube portion 91 is inserted into the opening 74 and the valve seat 90 a is disposed in the valve body housing portion 70. It extends to be the same height as 23. Furthermore, the outer diameter of the guide wall portion 94 is sized to match the inner diameter of the valve body housing portion 70, and can be arranged in the valve body housing portion 70 without backlash. In relation to this, the valve body accommodating portion 70 has a shape in which the guide rib 78 is not provided on the inner periphery thereof, but instead, an angular rib is provided on the inner periphery of the guide wall portion 94 of the valve seat 90a. Guide ribs 78 including 78a and intermediate ribs 78b are provided in the same manner as the inner periphery of the valve body accommodating portion 70 of the above-described embodiment (see FIG. 10). In the invention according to this embodiment, the inner diameter of the guide wall portion 94 means the inner diameter of the portion including the tip portion of each guide rib. That is, the inner diameter of the guide wall portion 94 is a size that substantially matches the outer diameter of the valve body 80.

  Further, an outflow hole 94 a is formed on one side wall of the guide wall portion 94 at a position substantially aligned with the outflow port 76 provided in the front wall 72 of the valve body housing unit 70, and fuel vapor is supplied to the outflow port 76. It can be introduced (see FIG. 9).

  In addition, as shown in FIG. 8, the valve seat 90a of this embodiment is inserted from the upper opening part of the valve body accommodating part 70, and after making the cylinder part 91 contact | abut to the inner periphery of the opening part 74, it is a guide wall. The valve seat 90 is attached to the opening 74 by fixing the portion 94 to the valve body housing portion 70 by fixing means such as welding.

  And according to this embodiment, since the guide wall part 94 is integrally formed in the periphery of the flange part 93 of the valve seat 90a, the valve body 80 slides away from the valve seat 90a by this guide wall part 94. When operating, the valve body 80 can slide smoothly, and when the valve body 80 contacts the valve seat 90a, the valve body 80 does not tilt and contacts the valve seat 90a in a stable posture. Thus, the sealing performance between the valve body 80 and the valve seat 90a can be further improved.

  FIG. 11 shows still another embodiment of the relief valve of the present invention. Note that substantially the same parts as those of the above-described embodiment are denoted by the same reference numerals, and description thereof is omitted.

  In this embodiment, like the valve device 10 of the above embodiment, the relief valve is not integrated with the cut valve, and the relief valve is made as a single part and attached in the middle of a fuel vapor pipe (not shown). Is different.

  That is, the relief valve 10 a has connection pipes 77 connected to fuel vapor pipes (not shown) on both sides, and a valve body housing part 70 for housing the slide cylinder 81 is formed between the connection pipes 77. The valve body accommodating part 70 consists of a substantially cylindrical casing, the opening part 74 is formed in the lower end surface, and the upper cap 50 is mounted | worn with the upper end surface. The upper cap 50 has a columnar support protrusion 55 that enters the valve body housing portion 70, and a spring 95 is attached to the outer periphery of the support protrusion 55, and one end of the spring 95 abuts on the inner surface of the upper cap 50. The other end is supported by the bottom wall 82 of the slide cylinder 81, the valve body 80 is pressed toward the opening 74, and abuts against the front end surface of the valve seat 90 attached to the opening 74. The part 74 is always closed.

  In the relief valve 10a, a fuel vapor pipe connected to a fuel tank is connected to one connection pipe 77, and a fuel vapor pipe connected to a canister (not shown) is connected to the other connection pipe 77, so that the fuel vapor pipe is connected. It is arranged in the middle of the piping. When the pressure in the fuel tank rises above a predetermined value, the valve body 80 slides upward against the urging force of the spring 95, the valve body 80 is opened away from the opening 74, and the fuel vapor Can be released to a canister (not shown).

  In this relief valve 10a as well, the surface of the valve seat 90 that is formed separately from the valve body housing portion 70 and that contacts the valve body 80 has a flatness of 0.02 mm or less and a surface roughness of Since the maximum height Ry is formed to be 1 μm or less, the sealing performance between the valve body 80 and the valve seat 90 when the valve body 80 is closed can be improved.

It is a disassembled perspective view which shows the valve apparatus provided with the relief valve of this invention. It is sectional drawing of the valve apparatus. It is a principal part expanded sectional view of the valve apparatus. It is an expanded sectional view in the AA arrow line of FIG. It is sectional drawing which shows the 1st operation state of the valve apparatus provided with the relief valve of this invention. It is sectional drawing which shows the 2nd operation state of the valve apparatus. It is sectional drawing which shows the 3rd operation state of the valve apparatus. FIG. 5 is an exploded perspective view showing another embodiment of the relief valve of the present invention and showing a valve device provided with the relief valve. It is principal part sectional drawing of the valve apparatus. In the same valve device, it is a sectional view in the state where a slide cylinder was stored in a valve body storage part. It is sectional drawing which shows other embodiment of the relief valve of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel tank 10 Valve apparatus 10a Relief valve 70 Valve body accommodating part 74 Opening part 80 Valve body 90,90a Valve seat 91 Tube part 93 Flange part 94 Guide wall part 95 Spring

Claims (2)

The fuel tank is disposed in a fuel vapor discharge passage that allows the inside of the fuel tank and a canister disposed outside the fuel tank to communicate with each other, and when the pressure in the fuel tank exceeds a predetermined value, In a relief valve for discharging fuel vapor into the discharge passage,
A valve body accommodating portion provided in the discharge passage; an opening for communicating the inside of the fuel tank formed at one end of the valve body housing portion with the discharge passage; and opening and closing the opening. Similarly to the valve body slidably disposed in the valve body housing portion, the valve body is also disposed in the valve body housing portion, and presses the valve body toward the opening portion, and is elastically biased so as to always close the opening portion And a spring to
A valve seat molded separately from the valve body housing portion is attached to the opening, and the valve seat comes into contact with the valve body to close the opening,
The valve seat has a cylinder part inserted into the inner periphery of the opening part, and a flange part formed on the outer periphery of the cylinder part and in contact with the outer periphery or the inner periphery of the opening part,
A relief valve characterized in that the surface of the valve seat that contacts the valve body is formed so that the flatness is 0.02 mm or less and the maximum height Ry of the surface roughness is 1 μm or less. .   The flange portion of the valve seat is in contact with the inside of the opening, and the peripheral edge of the flange portion extends to a side opposite to the cylindrical portion with a predetermined length and conforms to the outer diameter of the valve body. The relief valve according to claim 1, wherein the guide wall portion having an inner diameter is integrally formed.

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