JP2018132447A - Sealing device for leakage detection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing device for leakage inspection with which it is possible to obtain highly reliable inspection results.SOLUTION: A sealing device 10 for leakage inspection comprises a cylindrical cylinder 40, a piston 30, a spring 60, and a packing member 20. The piston is slidably provided in the cylinder, and has a first passage 32 that communicates with the inside of a fuel inspection valve 1 as an object to be inspected. The spring urges the piston toward the fuel injection valve side. The packing member 20 is provided on the fuel injection valve side of the piston and elastically deformable when the cylindrical tip is depressed, and has a small diameter part 21 located on the fuel injection valve side in the axial direction of the piston, a large diameter part 22 located on the opposite side to the fuel injection valve side of the small diameter part, and a second passage 23 penetrating the small diameter and large diameter parts and communicating with the first passage, the small diameter and large diameter parts forming a coaxially arranged stepped shape.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a sealing device for leak inspection.

  Conventionally, when a leakage inspection is performed on an inspection object having a cylindrical tip, it is necessary to keep the inside of the inspection object airtight as preparation prior to the leakage inspection. For example, Patent Literature 1 discloses a leak inspection seal device for keeping the inside of an inspection object airtight.

Japanese Patent No. 4392968

  Incidentally, a fuel injection valve that injects fuel into a cylinder in an internal combustion engine includes a cylindrical injector body, a needle that opens and closes an injection hole, a spring that urges the needle in a valve closing direction, an injection nozzle body, and the like. The fitting portion between the injector body and the injection nozzle body is fixed by welding so that the seal inside the body is maintained.

  In the manufacturing process, a leak inspection is performed to determine whether or not a leak has occurred in such a weld. In the leak inspection, the tip of the nozzle of the fuel injection valve is pressed against the packing member of the seal device for leak inspection, and the inspection gas is supplied from the fuel supply side. The conventional packing member is a member in which a passage is formed at the center and the entire shape is, for example, a simple truncated cone shape. The leak inspection sealing device is arranged in the chamber, and the gas leaking into the chamber is detected by a detector arranged outside the chamber to inspect the leakage.

  However, the leak inspection may be performed in a state where the spring for urging the needle in the valve closing direction is not yet installed due to a specification change in the manufacturing process. At this time, the valve is normally opened, and when the inspection gas is sealed in the body, the inspection gas flows out from the injection hole. In this case, the packing member of the conventional seal device for leak inspection cannot withstand high pressure, and the seal leak in the packing member is erroneously detected, leading to over-determination of a non-defective product as a defective product. There was a problem that it could not be done accurately.

  Also, there are various types of welding between the injector body and the injection nozzle body, such as outer periphery welding for welding the entire outer periphery of the injection nozzle body, and fillet welding that is stronger and stronger. For example, in the outer periphery welding, even when sealing is performed on a relatively wide surface of the packing member having a truncated cone shape, the welded portion is not covered. However, in the case of fillet welding, since the welded part is located closer to the tip of the nozzle, it is conceivable that the packing part covers the welded part. In this case, even if the packing member can withstand high pressure, leakage from the welded part cannot be accurately detected, and a defective product may be erroneously detected as a non-defective product.

  The present invention has been created in view of such a point, and an object of the present invention is to provide a sealing device for leak inspection that can obtain a more reliable inspection result.

  The sealing device for leak inspection of the present invention is a device that seals the cylindrical tip (44) of the inspection object (1) to be inspected for leakage. The seal device for leak inspection includes a cylindrical cylinder (40), a piston (30), a biasing member (60), and a packing member (20). The piston is slidably provided in the cylinder and has a first passage (32) communicating with the inside of the object to be inspected. The biasing member biases the piston toward the object to be inspected. The packing member (20) is provided on the inspection object side of the piston, and is elastically deformable when the cylindrical tip is pressed. The small diameter part (21) and the small diameter located on the inspection object side in the axial direction of the piston. A large-diameter portion (22) located on the opposite side of the inspection object side of the portion, and a second passage (23) that penetrates the large-diameter portion and the small-diameter portion and communicates with the first passage. And a large-diameter portion have a stepped shape arranged on the same axis.

  According to the configuration of the present invention, when the inspection object is attached to the leakage inspection seal device, the small diameter portion of the packing member provided at the tip of the piston receives the urging force of the urging member toward the inspection object side. Then, it is firmly pressed against the cylindrical tip of the object to be inspected. The packing member against which the cylindrical tip is pressed elastically deforms and seals the outer periphery of the cylindrical tip in an airtight state.

It is sectional drawing which shows an example of the fuel injection valve used as the object of a leak test. FIG. 2 is an enlarged view of the fuel injection valve shown in FIG. 1 and an enlarged view of a fillet weld. It is the perspective view which shows the sealing device for leak inspection by 1st Embodiment, and is the figure which looked at the state cut | disconnected along the central axis from the cutting end surface side. It is sectional drawing of the sealing apparatus for leak inspection by 1st Embodiment. It is a perspective view which shows a packing member. It is sectional drawing which shows a packing member. It is a work flowchart which shows a leak test procedure. It is a figure which shows the state which the packing member deform | transformed. It is a figure which shows the state which the packing member by the comparison form deform | transformed. It is a perspective view which shows the packing member by other embodiment.

Hereinafter, embodiments will be described with reference to the drawings.
<First Embodiment>
[Constitution]
The configuration of the first embodiment will be described with reference to FIGS. In this embodiment, the fuel injection valve 1 is employ | adopted as a to-be-inspected body which has a cylindrical front-end | tip part. Further, the leak inspection seal device 10 of this embodiment is provided in a chamber of a leak inspection device (not shown). First, the configuration of the fuel injection valve 1 as a leakage inspection target will be briefly described.

  The fuel injection valve 1 injects and supplies gasoline as fuel to the engine at a high pressure. As shown in FIG. 1, the fuel injection valve 1 includes a fixed core 2, a movable core 3, a housing 4, a first spring 5, a needle 6, and the like.

  The housing 4 includes a first cylinder member 41, a second cylinder member 42, a third cylinder member 43, and an injection nozzle 44. The first cylinder member 41, the second cylinder member 42, and the third cylinder member 43 are all formed in a cylindrical shape. The injection nozzle 44 is formed in a bottomed cylindrical shape. And it arrange | positions so that it may become coaxial in order of the 1st cylinder member 41, the 2nd cylinder member 42, the 3rd cylinder member 43, and the injection nozzle 44, and is mutually connected. An injection hole 46 is formed in the center of the bottom 45 of the injection nozzle 44. The injection nozzle 44 corresponds to a “cylindrical tip”.

  As shown in FIG. 2, in the housing 4, the fitting portion between the third cylindrical member 43 and the injection nozzle 44 is coupled by fillet welding, thereby forming a fillet weld portion 47. The leak inspection apparatus inspects whether there is no leak in the body welded portion of the housing 4 such as the fillet welded portion 47, for example.

  The fixed core 2 is formed in a substantially cylindrical shape by a magnetic material such as ferritic stainless steel. The fixed core 2 is subjected to a magnetic stabilization process. The fixed core 2 is provided so as to be fixed inside the first cylinder member 41 of the housing 4. The fixed core 2 and the first cylinder member 41 of the housing 4 are welded.

  The first spring 5 is provided so that one end thereof is in contact with the surface of the movable core 3 on the injection nozzle 44 side. The other end of the first spring 5 is in contact with the inner wall of the third cylinder member 43. The first spring 5 urges the movable core 3 in the direction opposite to the nozzle hole 46, that is, in the valve opening direction. The upper side shown in FIG. 1 is the valve opening direction, and the lower side is the valve closing direction. Hereinafter, the upper side of the drawing in the valve opening direction is also referred to as “one side”, and the lower side of the drawing in the valve closing direction is also referred to as “the other side”.

  In addition, the fuel injection valve 1 shown in FIG. 1 is a thing in the middle of manufacture when a leak test is implemented, and is not a finished product. When the fuel injection valve is completed, an adjusting pipe, a second spring, and the like (not shown) are arranged in the passage 11 formed inside the fixed core 2 in addition to the members shown in FIG. The second spring biases the needle 6 in the valve closing direction. However, since the second spring is not arranged at the leak inspection stage, the valve is always open.

  Next, the leak inspection seal device 10 for holding the inside of the fuel injection valve 1 in an airtight manner during the leak inspection of the fuel injection valve 1 will be described. As shown in FIGS. 3 and 4, the leakage inspection seal device 10 includes a packing member 20, a piston 30, a piston guide 40, a filter member 50, a spring 60, a fixing flange 70, and a work guide 80 (shown only in FIG. 4). ) Etc.

  The fixing flange 70 is fixed in a chamber (not shown) by a bolt 71 (see FIG. 4). As a result, the entire leak inspection seal device 10 is fixed in the chamber. The piston guide 40 is a cylindrical member, and is provided on the packing member 20 side of the fixing flange 70.

  The piston 30 is a cylindrical member disposed in the piston guide 40. A piston 60 is slidable by a spring 60 connected to the other side of the piston 30. The spring 60 biases the piston 30 toward the fuel injection valve 1 side. An O-ring 31 is disposed between the piston 30 and the piston guide 40. A filter member 50 is provided in the middle of the first passage 32 in the piston 30. The filter member 50 is for preventing foreign matters such as dust from entering the fuel injection valve 1 at the time of leak inspection, and is fixed in the piston 30 by a fixing screw 51.

  The work guide 80 (see FIG. 4) is a cylindrical member whose outer shape is a square shape, and is disposed on the outer periphery of the piston guide 40 on the packing member 20 side. The work guide 80 is for guiding the fuel injection valve 1 so that the fuel injection valve 1 is not displaced when the tip of the fuel injection valve 1 is pushed into the packing member 20.

  The packing member 20 is made of an elastically deformable material such as urethane, and is press-fitted and fixed to the end of the piston 30 on the fuel injection valve 1 side. As shown in FIGS. 5 and 6, the packing member 20 includes a small diameter portion 21, a large diameter portion 22, and a second passage 23. The large-diameter portion 22 is positioned on the fixing flange 70 side of the small-diameter portion 21 and is formed integrally with the small-diameter portion 21 and coaxially. Further, the large diameter portion 22 has a truncated cone shape whose diameter gradually increases from the fuel injection valve 1 side toward the opposite side in the axial direction. The second passage 23 passes through the centers of the small diameter portion 21 and the large diameter portion 22.

  An R-shaped portion 24 is formed on the outer periphery of the small diameter portion 21. The R-shaped portion 24 is concave on the shaft side so that the diameter gradually increases toward the large-diameter portion 22. The ratio between the height H of the small diameter portion 21 and the size of R of the R-shaped portion 24 is approximately 1: 1. Further, the diameter of the small diameter portion 21 is substantially smaller than the diameter of the bottom portion 45 of the injection nozzle 44, and the diameter of the large diameter portion 22 is generally large.

  A leak inspection apparatus (not shown) includes the leak inspection seal apparatus 10 described in detail above, a chamber, a gas supply unit, a vacuum pump, a detector, and the like. The leak test seal device 10 is fixed in the chamber. The vacuum pump evacuates air in a chamber that is a closed space. A detector provided outside the chamber detects the tracer gas leaking into the chamber during the leak inspection.

  Next, the leakage inspection of the fuel injection valve 1 performed using the leakage inspection sealing device 10 of the present embodiment will be described. As shown in FIG. 7, first, in step 100 (hereinafter, step is abbreviated as “S”), the fuel injection valve 1 as the object to be inspected is set in the leakage inspection seal device 10 in the chamber. At this time, the stepped portion 48 (see FIG. 1) of the third cylindrical member 43 of the fuel injection valve 1 is set to a predetermined seating reference, the injection nozzle 44 side is pressed against the packing member 20, The other side is also sealed.

  Next, in S200, the air in the chamber is evacuated by the vacuum pump. Next, in S300, the tracer gas is sealed from the fuel introduction opening 12 formed on one side of the fuel injection valve 1. In this state, the tracer gas leaking from the chamber is detected by the detector in S400. If this detected value exceeds the threshold value, it is determined that there is a leak. Next, in S500, the vacuum in the chamber is broken and the atmosphere is released to complete the inspection.

  In the leak inspection, the packing member 20 to which the injection nozzle 44 of the fuel injection valve 1 is strongly pressed is elastically deformed as shown in FIG. In FIG. 8, only the packing member 20 is illustrated in the leakage inspection seal device 10. As shown in FIG. 8, the packing member 20 is deformed by being compressed up and down, and in particular, the small-diameter portion 21 is compressed and its height becomes smaller than the original height H. However, the fillet weld portion 47 is not covered by the packing member 20.

  Further, when the injection nozzle 44 of the fuel injection valve 1 is installed in the leakage inspection seal device 10, the packing member 20 is moved in the axial direction by the spring 60 mounted just below the piston 30. As a result, the variation in the length L (see FIG. 1) from the stepped portion 48 of the third cylinder member 43 to the bottom 45 of the injection nozzle 44, which is called the neck length of the fuel injection valve 1, is absorbed.

[effect]
(1) For example, in the case of the packing member 25 having a shape of only the large-diameter portion 22, that is, a simple trapezoidal shape rather than a step as in the comparative embodiment shown in FIG. 9, the fuel injection valve of the packing member 25 The wide side surface comes into contact with the bottom 45 of the injection nozzle 44, and the packing member 25 may be deformed to cover the fillet weld 47. Thus, if the fillet welded portion 47 is covered, even if there is a seal leak in the fillet welded portion 47, the leak cannot be detected in the inspection. That is, the inspection cannot be performed correctly and the reliability is lacking.

  In this respect, in the present embodiment, the small diameter portion 21 that is relatively smaller than the large diameter portion 22 is sealed with the surface on the fuel injection valve side, and even if the small diameter portion 21 is pressed and deformed, the fillet weld portion 47 is reached. It does not cover, and it is possible to reliably inspect the welded portion that is the subject of leakage inspection.

  (2) Further, for example, when the needle 6 is normally closed, there is no gas leakage from the nozzle hole 46, so a seal that can stop a very small amount of leakage between the needle 6 and the seat surface is sufficient. However, as described above, in the present embodiment, the needle 6 is always open during the inspection, and the tracer gas leaks from the injection hole 46, so that a high pressure of 4 MPa or more is applied to the packing member. The packing member of the comparative form could not withstand such a high pressure.

  In this regard, according to the present embodiment, the packing member 20 comes into close contact with the bottom 45 of the injection nozzle 44 by receiving the biasing force toward the fuel injection valve 1 by the spring 60 without covering the fillet welded portion 47. That is, it becomes possible to seal strongly by the packing member 20, and to be able to withstand the high pressure.

  (3) In the leakage inspection seal device 10 of the present embodiment, the fuel injection valve 1 that is normally open is the inspection target, but even a fuel injection valve that is normally closed can be used. Of course, the housing 4 and the injection nozzle 44 may be of a conventional type by peripheral welding instead of fillet welding. That is, the leak inspection seal device 10 of the present embodiment is not limited to the welding mode of the fuel injection valve to be inspected or the open / closed state of the needle 6, and can test various fuel injection valves. Excellent in versatility.

  (4) In this embodiment, the piston 30 and the spring 60 are provided, and the packing member 20 fixed to the piston 30 is movable in the axial direction. Thereby, the dispersion | variation in the neck length L of the fuel injection valve 1 can be absorbed.

  (5) In the present embodiment, the large diameter portion 22 of the packing member 20 has a truncated cone shape whose diameter gradually increases from the fuel injection valve 1 side toward the opposite side in the axial direction. When the fuel injection valve 1 is removed, a force toward the fuel injection valve 1 in the direction of removal acts on the packing member 20. In other words, the packing member 20 is subjected to a force in the direction of being removed from the piston 30 every time the object to be inspected is replaced, but has a truncated cone shape so that it is difficult to be removed during repeated inspections.

  (6) In the present embodiment, the R-shaped portion 24 is provided in the packing member 20, so that the configuration is more excellent in durability. According to the results of the displacement test by the applicant of the present embodiment having the R-shaped portion 24 and the embodiment in which the R-shaped portion 24 is not provided, the present embodiment having the R-shaped portion 24 has higher durability. It turns out to have. In the durability test, the packing member 20 was separated with a mesh and subjected to stress analysis, and the displacement was measured.

  (7) In this embodiment, since the filter member 50 is provided, it can suppress that a foreign material mixes in the fuel injection valve 1 from the leak test | inspection seal apparatus 10 side.

<Other embodiments>
In the above-described embodiment, the fuel injection valve 1 is used as an object to be inspected. However, a pump-related member is used as long as it has a cylindrical tip and performs a leak inspection while keeping the inside airtight. Other members may be used.

  Further, in the above embodiment, the fuel injection valve 1 is a type having the single needle 6 and the injection hole 46 on the substantially central axis. Is possible. For example, a double needle type including an inner needle and an outer needle may be used, or a plurality of nozzle holes may be provided on the outer periphery of the central axis. In addition, the leakage inspection sealing device 10 of this embodiment can be applied to the welding mode of the housing 4 even if it is a type of peripheral welding instead of fillet welding.

  In the above embodiment, the filter member 50 may be omitted.

  In the above embodiment, the large-diameter portion 22 of the packing member 20 has a truncated cone shape, but may have other shapes.

  In the above embodiment, the R-shaped portion 24 is formed in the small-diameter portion 21 of the packing member 20, but there is no R-shaped portion like the packing member 26 shown in FIG. A simple stepped shape having the portion 211 may be used.

  The present invention is not limited to the embodiments described above, and can be implemented in various forms without departing from the spirit of the invention.

1 ... Fuel injection valve (inspected object)
DESCRIPTION OF SYMBOLS 10 ... Seal apparatus 20 for leak inspection ... Packing member 21 ... Small diameter part 22 ... Large diameter part 23 ... 2nd channel | path 24 ... R-shaped part 30 ... Piston 32 ... -1st channel | path 40 ... cylinder 50 ... filter member 60 ... spring (biasing member)

Claims (5)

A seal device for leak inspection that seals the cylindrical tip (44) of a test object (1) to be inspected for leak,
A cylindrical cylinder (40);
A piston (30) provided in a slidable manner in the cylinder and having a first passage (32) communicating with the inside of the object to be inspected;
A biasing member (60) for biasing the piston toward the object to be inspected;
A small diameter portion (21) provided on the inspection object side of the piston and elastically deformable when the cylindrical tip is pressed, and located on the inspection object side in the axial direction of the piston, the small diameter portion A large-diameter portion (22) located on the opposite side of the object to be inspected, and a second passage (23) that penetrates the large-diameter portion and the small-diameter portion and communicates with the first passage. A packing member (20) having a stepped shape in which the small diameter portion and the large diameter portion are arranged coaxially;
A leak inspection seal device comprising:   The leak inspection seal device according to claim 1, wherein an R-shaped portion (24) that is concave on the shaft side is formed on an outer periphery of the small-diameter portion so that the diameter increases toward the large-diameter portion. .   The leak inspection seal device according to claim 1, wherein the large diameter portion is formed in a truncated cone shape having a diameter that increases from the inspection object side toward the opposite side.   The leak inspection seal device according to any one of claims 1 to 3, wherein a filter member (50) is provided in the first passage of the piston.   The leak inspection according to any one of claims 1 to 4, wherein a surface of the small-diameter portion on the inspection object side is in contact with a bottom portion (45) of a fuel injection valve as the inspection object. Sealing device.

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