Piping connection structure

Abstract

To pull out only a pipe in pulling out the pipe disposed outside of a case from a through hole.SOLUTION: In a pipe connection structure for connecting a first pipe 1 and a second pipe 2 via a gasket 3 in a state of sealing a part between a through hole 10A formed on a wall body 101 of a case 100 and the first pipe, and a part between the through hole and the second pipe, the gasket has: a cylindrical first holding portion externally fitted to one end 1a of the first pipe; an inner peripheral first lip portion 32 formed on an inner peripheral surface of the first holding portion and elastically kept into contact with an outer peripheral surface 1aa of the first pipe; an outer peripheral lip portion 31 formed on an outer peripheral surface of the first holding portion and elastically kept into contact with an inner peripheral surface of the through hole; a cylindrical second holding portion externally fitted to an end portion 2a of the second pipe disposed in the case; and an inner peripheral second lip portion 43 formed on an inner peripheral surface of the second holding portion and elastically kept into contact with an outer peripheral surface of the second pipe. Resistance applied to the first holding portion in pulling out the first pipe from the through hole is smaller than the total pulling-out resistance of the outer peripheral lip portion and the inner peripheral second lip portion.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a piping connection structure that connects a first pipe arranged outside a case to a second pipe arranged inside the case in a sealed state, for example, via a gasket that connects the first pipe to a through hole provided in the case. [Background technology]

[0002] Examples of disclosures of the above-described connection structure include Patent Document 1 and Patent Document 2 listed below. Patent Document 1 and Patent Document 2 listed below describe a gasket that seals between a through hole provided in a wall of a case and a pipe inserted into the through hole. In this gasket, an inner seal area on the inner periphery, where an inner peripheral lip portion that elastically contacts the outer peripheral surface of the pipe is arranged, is located so as not to radially overlap with an outer seal area on the outer periphery, where an outer peripheral lip portion that elastically contacts the inner peripheral surface of the through hole is arranged. This suppresses the effect of eccentricity on the seal surface pressure and reduces the pipe insertion load, resulting in a gasket that is easy to assemble. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6818303 [Patent Document 2] Japanese Patent Publication No. 2020-41632 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described connection structure, the piping arranged outside the case may be removed during maintenance or the like. However, the structures disclosed in Patent Documents 1 and 2 are designed to be designed so that when the piping arranged outside the case is pulled out from the through-hole, not only the piping but also the gasket is pulled out and removed, and are not designed to allow only the piping arranged outside the case to be pulled out. If a fluid such as a cooling medium flows through the piping, if the gasket is pulled out along with the piping during maintenance, the through-hole will no longer be sealed, and there is a risk that the fluid, dust, or the like may enter the case through the through-hole.

[0005] The present invention has been made in consideration of the above-mentioned situation, and aims to provide a piping connection structure that allows only the piping arranged outside the case to be pulled out from the through hole. [Means for solving the problem]

[0006] In order to achieve the above object, a pipe connection structure according to the present invention is a pipe connection structure that connects a first pipe arranged outside a case and a second pipe arranged inside the case via a gasket, in a sealed state between a through hole provided in a wall of the case and the first pipe, and between the through hole and the second pipe, wherein the gasket includes a cylindrical first holding portion that is fitted onto one end of the first pipe, an inner peripheral first lip portion that is formed on an inner peripheral surface of the first holding portion and that elastically contacts an outer peripheral surface of the first pipe, and The case has an outer peripheral lip portion formed on the outer peripheral surface of the first retaining portion and elastically contacting the inner peripheral surface of the through hole, a cylindrical second retaining portion that is externally fitted onto the end of the second piping arranged in the case, and an inner peripheral second lip portion formed on the inner peripheral surface of the second retaining portion and elastically contacting the outer peripheral surface of the second piping, and is configured so that the resistance applied to the first retaining portion including the inner peripheral first lip portion when the first piping is pulled out of the through hole is smaller than the combined resistance in the pulling direction that occurs in each of the outer peripheral lip portion and the inner peripheral second lip portion.

[0007] In the above configuration, a lubricant may be applied to a portion of the inner peripheral first lip portion that elastically contacts the outer peripheral surface of the first pipe. Also, in the above configuration, the first pipe may have an annular groove into which the first holding portion is fitted, and the first holding portion may have a flat portion that is formed flat so as to abut along the outer peripheral wall of the groove, and a lubricant may be applied to a portion of the flat portion that elastically contacts the outer peripheral wall. Furthermore, in the above configuration, the case may be a case that houses an electronic device, and a cooling medium that cools the electronic device may circulate through the first pipe and the second pipe. [Effects of the Invention]

[0008] The pipe connection structure according to the present invention has the above-described configuration, so that when the pipe arranged outside the case is pulled out from the through-hole, only the pipe can be pulled out. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic perspective view showing a case, pipes, etc. to which the pipe connection structure according to one embodiment of the present invention is applied, for explaining an example in which the structure is applied; [Figure 2] FIG. 2 is a diagram for explaining the pipe connection structure according to the embodiment, and is a schematic partial cross-sectional view showing a connection portion between the case and the pipe shown in FIG. 1. [Figure 3] 10 is a diagram for explaining the pipe connection structure according to the embodiment, and is a schematic partial cross-sectional view showing a process of pulling out one of the pipes connected to each other via a gasket. FIG. [Figure 4] FIG. 10 is a diagram for explaining the pipe connection structure according to the embodiment, and is a schematic partial cross-sectional view showing a state in which only one of the pipes is pulled out from a state in which the pipes are connected to each other via a gasket. [Figure 5] FIG. 4 is a schematic cross-sectional view illustrating a gasket used for connecting pipes according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that in some drawings, some of the detailed reference numerals used in other drawings are omitted. Also, in Fig. 5, the gasket 3 in its original shape, not elastically deformed, is shown by solid lines to clearly explain the shapes of the components of the gasket 3. However, in reality, the gasket 3 is assembled in an elastically deformed state as shown in Figs. 2 to 4.

[0011] The piping connection structure of this embodiment connects a first piping 1 arranged outside the case 100 and a second piping 2 arranged inside the case 100 via a gasket 3, with the through hole 10A provided in the wall 101 of the case 100 and the first piping 1, and the through hole 10A and the second piping 2 being sealed. The gasket 3 has a cylindrical first retaining portion 30 fitted onto one end 1a of the first pipe 1, an inner circumferential first lip portion 32 formed on the inner circumferential surface 30a of the first retaining portion 30 and in elastic contact with the outer circumferential surface 1aa of the first pipe 1, an outer circumferential lip portion 31 formed on the outer circumferential surface 30b of the first retaining portion 30 and in elastic contact with the inner circumferential surface 10a of the through hole 10A, a cylindrical second retaining portion 40 fitted onto the end 2a of the second pipe 2 disposed in the case 100, and an inner circumferential second lip portion 42 formed on the inner circumferential surface 40a of the second retaining portion 40 and in elastic contact with the outer circumferential surface 2aa of the second pipe 2. In this pipe connection structure, the resistance applied to the first retaining portion 30 including the inner circumferential first lip portion 32 when the first pipe 1 is pulled out of the through hole 10A is smaller than the combined resistance in the pulling direction generated by the outer circumferential lip portion 31 and the inner circumferential second lip portion 42. Details are provided below.

[0012] The piping connection structure of this embodiment can be applied, for example, as a structure for connecting a cooling pipe of a cooler that cools automotive electronic devices with a coolant to an external hose. Such a piping connection structure is required to not only prevent leakage of the coolant but also to withstand intrusion of rainwater and the like from the outside and sprays of water used when high-pressure washing a vehicle, and to maintain a seal that can be maintained even if the piping is eccentric. Furthermore, a structure is required that allows only the external hose to be removed from the through-hole when performing maintenance, etc. The following describes a piping connection structure that connects a second piping 2 disposed within an inverter case 100 for an automobile to a first piping 1 disposed outside the inverter case 100 using a gasket 3. Note that the structure of the inverter case 100, which constitutes part of an actual power control unit (PCU), is complex, but is shown simplified in the figures.

[0013] <Inverter> When an automobile is equipped with an electric motor as a drive source, the operation of the electric motor is controlled by an inverter 20. The electric motor functions as a motor or the like that receives power from a battery and generates drive force, and the inverter 20 converts DC power supplied from the battery or the like into AC power through a switching action, and supplies power to the electric motor. The inverter 20 used in such an automobile is required to have a large amount of power, and large currents flow through the switching elements, etc., which generates a large amount of heat. Therefore, the inverter case 100 according to this embodiment employs a system that configures a coolant flow path within the inverter case 100 through which a coolant such as coolant water or coolant flows, thereby cooling the various electronic devices that make up the inverter 20.

[0014] The inverter case 100 is a box-shaped, generally rectangular parallelepiped structure divided into upper and lower halves. The inverter case 100 shown in FIG. 1 includes a lid case 100A, an upper case 100B, and a lower case 100C. The inverter case 100 is configured by stacking the upper case 100B on the lower case 100C, and then covering the upper case 100B with the lid case 100A. The inverter case 100 is made of a metal material such as aluminum or a resin material. A wall 101 disposed on the side of the upper case 100B is provided with an outlet 300 to which a pipe (not shown) for discharging the cooling medium to the outside of the upper case 100B is connected, and a circular through-hole 10A (see FIG. 2, etc.) to which one end 1a of the first pipe 1 is connected. A stepped portion 102 is provided around the through-hole 10A of the wall 101, and the stepped portion 102 is configured to accommodate a flange 12A on the one end 1a of the first pipe 1. As shown in FIG. 2 and other figures, the second pipe 2 is arranged so that the tip side of its end 2a is located within the through-hole 10A, and is configured to communicate with a cooling plate (not shown) provided in the stack unit 200. A wall 103 arranged on the side surface of the lower case 100C is provided with a circular through-hole 10B to which the other end 1b of the first pipe 1 is connected. A step 104 is provided around the through-hole 10B in the wall 103, and is formed to fit a flange 12B on the other end 1b side of the first pipe 1.

[0015] The cooling medium supplied into the lower case 100C from a supply port (not shown) of the lower case 100 passes through a cooling medium flow path 6 (see FIG. 2, etc.) provided in the lower case 100C, reaches a first pipe 1 and a second pipe 2, and circulates through the second pipe 2 in the cooling plate provided in the stack unit 200. Then, the cooling medium that has passed through the cooling medium flow path provided in the upper case 100B is finally discharged from a discharge port 300 provided in the upper case 100B.

[0016] <Gasket> The gasket 3 is a single component that connects the first pipe 1 and the second pipe 2 and forms a coolant flow path. The entire gasket 3 is a cylindrically molded elastic body made of rubber, elastomer, synthetic resin, or other rubber material, such as ethylene propylene rubber, butyl rubber, or silicone rubber. The gasket 3 has a first retaining portion 30, a second retaining portion 40, and a connecting portion 50. One end 3a of the gasket 3 is the end of the first retaining portion 30, and the other end 3b is the end of the second retaining portion 40. The first retaining portion 30 is fitted over the one end 1a of the first pipe 1 and is fitted into the inner circumferential surface 10a of the through hole 10A. The second retaining portion 40 is fitted over the end 2a of the second pipe 2. The connecting portion 50 is a member that connects the first holding portion 30 and the second holding portion 40, and because the connecting portion 50 itself has elasticity, it allows radial displacement even if the first pipe 1 and the second pipe 2 are eccentric. The outer diameter of the first pipe 1 is slightly larger than the outer diameter of the second pipe 2, and therefore the inner diameter of the first holding portion 30 is larger than the inner diameter of the second holding portion 40. Therefore, the connecting portion 50 that connects the first holding portion 30 and the second holding portion 40 has a tapered shape that gradually reduces in diameter from the first holding portion 30 toward the second holding portion 40.

[0017] <First piping, second piping> The first pipe 1 is made of a hollow cylindrical body made of resin, aluminum, or the like, and is formed in a substantially U-shape. As shown in FIG. 1 , one end 1a of the first pipe 1 is connected to the upper case 100B, and the other end 1b is connected to the lower case 100C. This allows the coolant that has passed through the upper case 100B and reached the second pipe 2 to be sent to a coolant flow path 6 provided in the lower case 100C. The second pipe 2 is made of a hollow cylindrical body made of resin, aluminum, or the like, and is provided to circulate the coolant that has passed through the cooling plate of the stack unit 200 to the first pipe 1.

[0018] As shown in FIG. 2 and other figures, one end 1a of the first pipe 1 is provided with an annular groove 11 and an annular flange 12A formed on the outer periphery of the groove 11 and protruding radially outward. The groove 11 has a bottom 11c, an inner circumferential wall 11a (which is also the outer circumferential surface 1aa of the first pipe 1), an outer circumferential wall 11b, and an opening 11d, and the first holding portion 30 of the gasket 3 is fitted into the groove 11. Lubricants G1 and G2 are applied to the fitting portion between the groove 11 and the first holding portion 30; these lubricants G1 and G2 will be described later. The groove 11 may have a strip-like slit (not shown) formed along the axial direction to serve as an air passage. For example, if a slit portion is formed along the outer peripheral wall 11b from the bottom 11c of the groove 11 to the opening 11d, air escapes from the slit portion when the first retaining portion 30 is fitted, facilitating insertion of the first retaining portion 30 of the gasket 3 into the outer peripheral surface 1aa of the first piping 1 (corresponding to the inner peripheral wall 11a of the groove 11). Furthermore, if a slit portion is formed, the lubricants G1 and G2 are retained in the slit portion when the first piping 1 is pulled out, reducing the resistance generated in the first retaining portion 30 and making it easier to pull out. The flange portion 12A has a diameter larger than that of the through hole 10A but smaller than that of the stepped portion 102 so that it can fit within the stepped portion 102 provided in the wall body 101. An insertion hole (not shown) is formed in the flange portion 12A for inserting a fastener such as a screw. Then, one end 1 a of the first pipe 1 can be fixed to the wall body 101 by fixing this flange portion 12 to the outer surface of the wall body 101 with a fixing tool (not shown).

[0019] The other end 1b of the first pipe 1 is provided with an annular flange 12B that protrudes radially outward. An insertion hole (not shown) is formed in flange 12B through which a fastener such as a screw can be inserted. The other end 1b of the first pipe 1 can be fixed to the wall 103 by fastening it to the outer surface of the wall 103 of the lower case 100C with a fastener (not shown). An annular ring gasket 7 with a generally circular cross section is attached between the tip 1ba of the other end 1b of the first pipe 1 and the outer wall 104a of the stepped portion 104. This seals the gap between the other end 1b of the first pipe 1 and its connection portion. The tip of the end 2a of the second pipe 2 is provided with a sloped tip 2ab (see FIG. 5) that is slightly smaller in diameter than the other portions to facilitate attachment and detachment of the gasket 3.

[0020] <1st holding part> As shown in FIG. 5 and other figures, the first retaining portion 30, which constitutes part of the gasket 3, has an inner peripheral first lip portion 32, an inner peripheral protrusion 33, an outer peripheral lip portion 31, a flat portion 34, and an end portion 35. The inner peripheral first lip portion 32 is a ring-shaped lip formed continuously in the circumferential direction and having a substantially right-angled triangular shape, and multiple inner peripheral first lip portions 32 of the same shape are provided. The portion of the inner peripheral first lip portion 32 corresponding to the hypotenuse elastically contacts the outer peripheral surface 1aa of the first pipe 1. As the inner peripheral first lip portion 32 is inserted into the groove 11, it elastically deforms, tilting, and fits into the groove 11 in this state. Therefore, the inner peripheral first lip portion 32 is elastically deformed in the direction opposite to the direction of insertion of the first pipe 1, and is fitted into the groove 11 (see the enlarged view of portion X in FIG. 2). The inner peripheral protrusion 33 is disposed adjacent to the inner peripheral first lip portion 32 and is formed in a generally isosceles triangle shape in cross section, with the amount of protrusion of the inner peripheral protrusion 33 being smaller than the amount of protrusion of the inner peripheral first lip portion 32. The outer peripheral lip portion 31 is a circumferentially continuous annular lip that elastically contacts the inner peripheral surface 10a of the through hole 10A with a tightening margin due to bending deformation. The amount of protrusion of the outer peripheral lip portion 31 is greater than the amount of protrusion of the inner peripheral first lip portion 32. The flat portion 34 is formed flat so as to abut along the outer peripheral wall 11b of the groove portion 11. The end portion 35 is formed flat so as to abut along the bottom portion 11c of the groove portion 11. A plurality of inner peripheral first lip portions 32 are disposed side by side, and the inner peripheral region where the plurality of inner peripheral first lip portions 32, 32 are arranged is referred to as the inner seal region S1. The inner sealing area S1 is a sealing portion that separates the coolant flow paths, and can be said to be an area that seals the coolant flow paths outside the inverter case 100. The outer peripheral area where the outer peripheral lip portion 31 is arranged is called the outer sealing area S2. The outer sealing area S2 can also be said to be a sealing area that separates the inside and outside of the inverter case 100.

[0021] According to the pipe connection structure of this embodiment, the inner seal region S1 and the outer seal region S2 are positioned so as not to overlap in the radial direction. Therefore, when the gasket 3 is fitted and assembled to one end 1a of the first pipe 1 and inserted into the through hole 10A of the wall body 101, an increase in insertion load can be prevented, improving assembly efficiency. Even if the axis L1 of the first pipe 1 and the axis L of the through hole 10A are misaligned and eccentric, the inner seal region S1 and the outer seal region S2 are positioned so as not to overlap in the radial direction, and sealing performance can be maintained without being affected by fluctuations in surface pressure or internal stress at the inner and outer seal regions S1 and S2 due to eccentricity. The inner seal region S1 is positioned on the opposite side of the outer seal region S2 in the insertion direction of the first pipe 1. The outer peripheral surface corresponding to the portion where the inner seal region S1 is formed is a flat portion 34 that fits into the groove portion 11 of the first pipe 1. Therefore, even if the first pipe 1 is eccentric, the plurality of inner peripheral first lip portions 32, 32 arranged in the inner seal area S1 maintains the sealing performance for the first pipe 1, and a stable sealing performance can be ensured.

[0022] Because the inner peripheral protrusion 33 is provided on the inner peripheral surface 30a corresponding to the position where the outer peripheral lip portion 31 is formed, even if a force is applied to the first pipe 1 to cause it to become eccentric, the posture of the first pipe 1 can be maintained in the correct position (a position where the axis of the first pipe 1 and the axis L of the through hole 10A are approximately aligned). Even if the first pipe 1 becomes eccentric, the inner peripheral protrusion 33 abuts against the outer peripheral surface 1aa of the first pipe 1, suppressing excessive compression of the inner peripheral first lip portion 32 and preventing an effect on the sealing surface pressure of the inner peripheral first lip portion 32, thereby maintaining stable sealing performance. Furthermore, when the pressure of the coolant passing through the first pipe 1 increases, a force is generated that tries to cause the first holding portion 30 attached to the first pipe 1 to come out of the groove portion 11, but the pressing force of the inner peripheral first lip portion 32 and the inner peripheral protrusion 33 acts to prevent the first holding portion 30 from coming out. In this embodiment, the inner peripheral protrusion 33 is illustrated as a contact with the outer peripheral surface 1aa of the first piping 1, but it may be in elastic contact when eccentric, but close to the outer peripheral surface 1aa (with a slight gap) when in the correct position.

[0023] An outer peripheral lip portion 31 that elastically deforms and abuts against the inner peripheral surface 10a of the through hole 10A is provided on the outer peripheral surface 30b of the first holding portion 30. The outer peripheral lip portion 31 deforms into a collapsed state as shown in Fig. 2 and other figures and elastically contacts the inner peripheral surface 10a of the through hole 10A, so that sealing with the inner peripheral surface 10a of the through hole 10A can be maintained even when the first pipe 1 or the second pipe 2 is eccentric, and high followability can be achieved by the bending deformation of the outer peripheral lip portion 31.

[0024] <Lubricant> As shown in the enlarged view of section X in FIG. 2 and the enlarged view of section Y in FIG. 4, a lubricant G1 is applied to the elastically contacting portion of the inner first lip portions 32, 32 of the first holding portion 30 with the outer peripheral surface 1aa of the first pipe 1. Furthermore, a lubricant G2 is applied to the elastically contacting portion of the flat portion 34 of the first holding portion 30 with the outer peripheral wall 11b. This configuration allows the resistance applied to the first holding portion 30, including the inner first lip portions 32, 32, when the first pipe is pulled out of the through hole to be smaller than the combined resistance in the pulling direction that occurs in the outer peripheral lip portion 31 and the inner second lip portion 42. In other words, the resistance (load) applied when the first pipe 1 is pulled out can be expressed as the inner seal region S1 < the outer seal region S2 + the lip-forming region A.

[0025] When the first pipe 1 and the second pipe 2 are connected via the gasket 3, in order to ensure a seal that can prevent leakage of the cooling medium in the first pipe 1 and the second pipe 2 and prevent intrusion of rainwater and the like from the outside (first pipe 1 side) of the inverter case 100, the resistance applied to the first holding portion 30 including the inner circumferential first lip portion 32 is made larger than the combined resistance in the pull-out direction that occurs in the outer circumferential lip portion 31 and the inner circumferential second lip portion 42. That is, to prevent the first pipe 1 from easily coming out of the through hole 10A, the compression amount of the various lips (inner circumferential first lip portion 32, outer circumferential lip portion 31, inner circumferential second lip portion 42, etc.) provided on the gasket 3 is set as high as possible within a range of, for example, 0.2 mm to 0.7 mm. The greater the compression amount, the better the seal, but the first pipe 1 cannot be pulled out alone during maintenance; if an attempt is made to pull out the first pipe 1, the gasket 3 will also be removed. However, as described above, applying lubricants G1 and G2 to the elastic contact portions of the inner peripheral first lip portions 32, 32 of the first retaining portion 30 that contact the outer peripheral surface 1aa of the first pipe 1 and the elastic contact portion of the flat portion 34 that contacts the outer peripheral wall 11b reduced the resistance of the inner seal region S1 by approximately 80% even with the same compression amount. Therefore, even after the first pipe 1 is removed from the through hole 10A for maintenance or other purposes, the gasket 3 and the second pipe 2 remain attached to the through hole 10A. This allows the outer peripheral lip portion 31 to seal between the through hole 10A and the first retaining portion 30, and the inner peripheral second lip portion 42 to seal between the second pipe 2 and the second retaining portion 40. Removing the first pipe 1 prevents the coolant flowing through the first pipe 1 and the second pipe 2 from entering the upper case 100B. Furthermore, the reduced insertion load facilitates assembly of the first pipe 1 and the gasket 3 during the production process or other processes.

[0026] The lubricants G1 and G2 are not particularly limited, but when the gasket 3 is made of, for example, ethylene propylene rubber, a silicone-based oil is suitable as it has little effect on the rubber material or the cooling medium. If a silicone-based oil is used, it will not evaporate or crystallize in the usage environment, and will not deteriorate surrounding parts or hinder the deformation of the gasket 3. For example, KF-96 1000CS manufactured by Shin-Etsu Chemical Co., Ltd. may be used as the silicone-based oil. The viscosity of the lubricants G1 and G2 is also not particularly limited, but the lower the viscosity, the more likely it is that friction will be reduced due to seepage and dripping, and the higher the viscosity, the worse the handling will be. Therefore, it is preferable to use a lubricant with a base oil kinematic viscosity of 700 mm at 25°C. 2 / S~1000mm 2 The method of applying the lubricants G1 and G2 to the elastic contact portions is not particularly limited, and the lubricants may be impregnated into a sponge or the like and transferred to the gasket 3, or may be applied to the groove portion 11.

[0027] <Connecting part> The connecting portion 50 connects the first holding portion 30 attached to one end 1a of the first pipe 1 and the second holding portion 40 attached to the end 2a of the second pipe 2, and is elastically deformable. The first holding portion 30 and the second holding portion 40 have different diameters depending on the diameters of the first pipe 1 and the second pipe 2, so the connecting portion 50 has a tapered shape.

[0028] The connecting portion 50 is provided with an outer peripheral protrusion 51 that is adjacent to the insertion direction side (second holding portion 40 side) of the outer peripheral lip portion 31, has a mountain-shaped cross section, and elastically contacts the inner peripheral surface 10a of the through hole 10A. The outer peripheral protrusion 51 may be formed continuously along the circumferential direction, or may be formed at appropriate intervals. The outer peripheral protrusion 51 is formed in a mountain-shaped cross section with a smaller protrusion amount than the outer peripheral lip portion 31. In this embodiment, an example is illustrated in which the outer protrusion 51 abuts against the inner surface 10a of the through hole 10A, but it may also be close to the inner surface 10a (with a slight gap) and make elastic contact when the first pipe 1 or the second pipe 2 becomes eccentric.

[0029] <Second holding part> The inner circumferential surface 40a of the second retaining portion 40 abuts against the outer circumferential surface 2aa of the second piping 2 and has a lip-forming region A where an annular inner circumferential second lip portion 42 is provided. An annular groove portion 41 is provided on the outer circumferential surface 40b of the second retaining portion 40 corresponding to the lip-forming region A formed on the inner circumferential surface 40a. This lip-forming region A is a sealing region that separates the coolant flow paths and can be said to be a region that seals the coolant flow paths within the inverter case 100. The groove portion 41 is formed in an annular shape along the circumferential direction, and a reinforcing ring 4 that reinforces the fit to the second piping 2 is housed in the groove portion 41 in a fitted state. The reinforcing ring 4 is an annular body made of a metal material, a synthetic resin material, or the like, and the groove depth and width of the groove portion 41 are determined according to the dimensions of the reinforcing ring 4. When the reinforcing ring 4 is accommodated in the groove portion 41 of the second holding portion 40 and fitted onto the second piping 2, it exerts a tightening action in the centripetal direction, strengthening the sealing force applied to the second piping 2 by the reinforcing ring 4 and the inner second lip portion 42, and enabling the second piping 2 to be held more stably.

[0030] A protrusion 43 is formed adjacent to the inner circumferential second lip portion 42 at an end of the second retaining portion 40, i.e., on the other end 3b side of the gasket 3. The protrusion 43 is formed continuously along the circumferential direction, and its top is formed with a mountain-shaped cross section that slopes away from the insertion direction to facilitate insertion of the gasket 3 into the second pipe 2. The protrusion 43 is formed to elastically contact the outer peripheral surface 2aa of the second pipe 2. The protrusion amount of the protrusion 43 and the distance between the protrusion 43 and the adjacent inner circumferential second lip portion 42 are desirably formed to be such that the protrusion 43 does not abut against the inner circumferential second lip portion 42 even when the protrusion 43 is fitted into the outer peripheral surface 2aa of the second pipe 2 and its top is slightly elastically deformed and tilted toward the inner circumferential second lip portion 42. In this structure, the protrusion amount of the protrusion 43 is smaller than the protrusion amount of the inner circumferential second lip portion 42.

[0031] Each of the inner second lip portions 42 has a mountain-shaped cross section, and multiple inner second lip portions 42 are formed in a ring shape along the circumferential direction, spaced at a fixed distance (interval). The amount of protrusion of the inner second lip portions 42, 42, 42 is greater than the distance between adjacent inner second lip portions 42, 42. The inner second lip portions 42 are configured to elastically contact the second piping 2 with an interference, and the distance between adjacent inner second lip portions 42, 42 is greater than the interference of the inner second lip portions 42. The second pipe 2 may vibrate, or thermal expansion may occur in the second pipe 2 depending on the material of the second pipe 2, but even in such cases, if the multiple inner circumferential second lip portions 42, 42 are provided as described above, they will not come into contact with each other when assembled to the second pipe 2, and will be able to follow the movement of the second pipe 2 and maintain sealing performance. Furthermore, because adjacent inner circumferential second lip portions 42, 42 will not come into contact with each other when assembled to the second pipe 2, the inner circumferential second lip portions 42 will adhere to each other (the inner circumferential second lip portions 42, 42 will not stick), preventing an excessive increase in lip reaction force and preventing an increase in insertion and extraction load, thereby improving insertion and extraction performance.

[0032] Next, with reference to FIG. 2, a procedure for connecting the first pipe 1 and the second pipe 2 at the through hole 10A using the gasket 3 configured as described above will be described. <Connection instructions> First, the reinforcing ring 4 is fitted into the groove 41 of the second retaining portion 40 of the gasket 3 in advance. Next, the first retaining portion 30 of the gasket 3 is fitted into the groove 11 of one end 1a of the first pipe 1, and the gasket 3 is assembled to the first pipe 1. During this assembly, the first inner lip portion 32 elastically deforms, tilting obliquely from the bottom portion 11c toward the opening 11d (resulting in the same state as shown in the enlarged view of portion X in Figure 2). The ring gasket 7 is then attached to the other end 1b of the first pipe 1. At this time, predetermined amounts of lubricants G1 and G2 have been applied to the first inner lip portions 32, 32 and flat portion 34 of the first retaining portion 30 of the gasket 3.

[0033] Then, first, the ring gasket 7, followed by the first pipe 1, is inserted through the through-hole 10B in the wall 103 from the other end 1b of the first pipe 1. At the same time, the gasket 3, followed by the first pipe 1, is inserted from the outside through the through-hole 10A in the wall 101. The other end 3b of the gasket 3 reaches the end 2a of the second pipe 2, and the top of the protrusion 43 first elastically contacts the tip 2ab of the second pipe 2. The tip 2ab is formed with a smaller diameter than the other portions of the second pipe 2 and is inclined so that the diameter gradually increases. Therefore, the protrusion 43, which is inclined in the direction opposite to the insertion direction, smoothly elastically deforms. Next, the inner second lip 42, located on the other end 3b side, elastically contacts the outer circumferential surface 2aa of the second pipe 2, is compressed and elastically deformed, and is fitted over the second pipe 2 in an obliquely inclined state. In this case, if the axes of the inserted first pipe 1 and second pipe 2 deviate from the axis L of the through hole 10A, the outer peripheral protrusion 51 abuts against the inner peripheral surface 10a of the through hole 10A, preventing eccentricity of the first pipe 1 and the second pipe 2 and reducing the effect on the sealing surface pressure of the outer peripheral lip portion 31. The outer peripheral protrusion 51 is located on the second retaining portion 40 side of the outer peripheral lip portion 31, opposite the direction in which the outer peripheral lip portion 31 falls, so they do not come into contact with each other. Furthermore, the outer peripheral protrusion 51 is located on the first retaining portion 30 side of the connecting portion 50, so it is structured to reliably abut against the inner peripheral surface 10a of the through hole 10A. Furthermore, the outer peripheral protrusion 51 also has the effect of removing foreign matter from the inner peripheral surface 10a of the through hole 10A when the gasket 3 is inserted, preventing foreign matter from becoming trapped at the contact surface of the outer peripheral lip portion 31.

[0034] As shown in FIG. 2, the first pipe 1 is inserted until its flanges 12A and 12B are seated within the stepped portions 102 and 104, respectively, and abut against the walls 101 and 103. At this time, the outer lip portion 31 of one end 1a of the first pipe 1 is in elastic contact with the inner circumferential surface 10a of the through hole 10A, and the ring gasket 7 is in elastic contact with the stepped portion 104 at the other end 1b. Since the inner seal region S1 and the outer seal region S2 of the gasket 3 are positioned so as not to overlap radially, an increase in insertion load can be prevented, improving assembly ease. Even if the axis L of the first pipe 1 and the axis L of the through hole 10A are misaligned and eccentric, the inner seal region S1 and the outer seal region S2 are positioned so as not to overlap radially, which minimizes the effect of surface pressure fluctuations and internal stresses on the inner and outer seal regions S1 and S2, thereby maintaining stable sealing performance. At this time, the connecting portion 50 has elasticity and can be displaced radially, so even if there is some misalignment between the axis L of the through hole 10A and the axis of the second pipe 2, this is absorbed by the elastic deformation of the connecting portion 50. In particular, since the connecting portion 50 has a tapered shape, this, combined with the fact that the connecting portion 50 itself is made of an elastic material, effectively absorbs the amount of eccentricity. Then, by fixing the flange portion 12A of the first pipe 1 to the wall body 101 with a fixing device (not shown), the connection of the first pipe 1 and the second pipe 2 is completed.

[0035] 2, an annular inner peripheral first lip portion 32 and an inner peripheral second lip portion 42 are respectively interposed in a compressed state on the outer fitting portion of the first holding portion 30 fitted onto the first pipe 1 and the outer fitting portion of the second holding portion 40 fitted onto the second pipe 2, thereby providing a highly sealed connection structure and allowing the coolant to flow between the first pipe 1 and the second pipe 2 via the gasket 3. Furthermore, an annular outer peripheral lip portion 31 is interposed in a compressed state between the first holding portion 30 and the through hole 10A, thereby sealing the inside and outside of the inverter case 100 through the through hole 10A and preventing dust and other foreign matter from entering the inverter case 100 from the outside through the through hole 10A.

[0036] Next, with reference to FIGS. 2 to 4, a procedure for pulling out the first pipe 1 connected as described above will be described. <Removal procedure> First, the fasteners (not shown) that secure the first pipe 1 to the walls 101 and 103 are removed, and a force is applied to grasp the first pipe 1 and pull it away from the second pipe 2, i.e., in the pulling direction. The resistance applied to the first holding portion 30, including the inner first lip portions 32, 32, is smaller than the combined resistance in the pulling direction that occurs in the outer peripheral lip portion 31 and the inner second lip portions 42, 42, 42. Therefore, only the first pipe 1 can be pulled out. In other words, if the resistance applied to the inner first lip portions 32, 32 when the first pipe 1 is pulled out of the through hole 10A were greater than the combined resistance in the pulling direction that occurs in the outer peripheral lip portion 31 and the inner second lip portions 42, 42, 42, 42, the gasket 3 would also be pulled out when the first pipe 1 is pulled out. However, with the above configuration, only the first pipe 1 can be pulled out when the first pipe 1 is pulled out of the through hole 10A.

[0037] In the above embodiment, a pipe connection structure is described in which a second pipe 2 disposed inside an inverter case 100 for an automobile is connected to a first pipe 1 disposed outside the inverter case 100 using a gasket 3. However, the present invention is similarly applicable to other pipe connection structures as long as the first pipe and the second pipe, which are axially spaced apart and arranged opposite each other in a through hole in a wall, are connected via a gasket. The configuration of the gasket 3 is also an example and is not limited to the illustrated example. The number and shapes (e.g., protrusion amount, protrusion width) of the inner second lip portion 42, the protrusion 43, the outer lip portion 31, the inner first lip portion 32, the inner protrusion 33, and the outer protrusion 51 are also not limited to the illustrated example. The shapes of the through holes 10A and 10B formed in the wall bodies 101 and 103 are also not particularly limited to the illustrated example and are formed according to the shape and size of the first pipe 1 (external hose) to be connected to the second pipe 2. Furthermore, the groove 11 and the flanges 12A and 12B may be formed integrally with the first pipe 1 as shown in FIG. 1, or may be formed as separate bodies that are fitted onto a cylindrical pipe. [Explanation of symbols]

[0038] 100 Inverter Case 101 Wall 10A through hole 10a Inner surface 1 First piping 2 Second piping 3. Connecting members 30 1st holding part 30b Outer surface 31 Outer lip 40 Second holding part 50 Joint 51 Outer peripheral protrusion

Claims

1. A pipe connection structure that connects a first pipe arranged outside a case and a second pipe arranged inside the case via a gasket in a sealed state between a through hole provided in a wall of the case and the first pipe, and between the through hole and the second pipe, the gasket has a cylindrical first retaining portion fitted onto one end of the first piping, a first inner lip portion formed on the inner peripheral surface of the first retaining portion and in elastic contact with the outer peripheral surface of the first piping, a first outer lip portion formed on the outer peripheral surface of the first retaining portion and in elastic contact with the inner peripheral surface of the through hole, a second cylindrical retaining portion fitted onto the end of the second piping disposed in the case, and a second inner lip portion formed on the inner peripheral surface of the second retaining portion and in elastic contact with the outer peripheral surface of the second piping, A piping connection structure characterized in that, when the first piping is pulled out of the through hole, the resistance applied to the first retaining portion including the inner first lip portion is smaller than the combined resistance in the pulling direction generated by each of the outer lip portion and the inner second lip portion.

2. In claim 1, A pipe connection structure, characterized in that a lubricant is applied to a portion of the inner peripheral first lip portion that elastically contacts the outer peripheral surface of the first pipe.

3. In claim 1 or claim 2, the first pipe has an annular groove into which the first holding portion is fitted, the first holding portion has a flat portion formed flat so as to abut along an outer peripheral wall of the groove portion, A pipe connection structure, characterized in that a lubricant is applied to the portion of the flat portion that elastically contacts the outer peripheral wall.

4. In claim 1 or claim 2, The case is a case in which an electronic device is housed, and a piping connection structure is provided in which a cooling medium for cooling the electronic device flows through the first piping and the second piping.

5. In claim 3, The case is a case in which an electronic device is housed, and a piping connection structure is provided in which a cooling medium for cooling the electronic device flows through the first piping and the second piping.

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