Resin tube

Abstract

The utility model provides a kind of resin pipe body for cooling of electric automobile, it has the features of the new shape of the thick wall of pipe body can be avoided and improve the pressure resistance performance Corrugated part.A kind of resin pipe body (10) for cooling of electric automobile, wherein, the curvature radius (Ra) of the outer surface center of valley (22) at corrugated part (12) is greater than the curvature radius (Rb) of inner surface center, and, the pipe thickness of valley (22) is greater than the pipe thickness of the boundary portion (34) of peak (20) and valley (22).

Description

Technical Field

[0001] This utility model relates to a resin pipe body for cooling piping in electric vehicles, and to a resin pipe body having a corrugated portion having peaks and valleys alternately arranged in the pipe length direction. Background Technology

[0002] In electric vehicles, as described in, for example, Patent Document 1 (Japanese Patent Application Publication No. 2022-135796), a non-conductive resin tube is used as the flow path for forming the cooling medium in the cooling system of heat-generating components such as batteries. Furthermore, in this invention, an electric vehicle refers to a self-propelled vehicle equipped with an electric motor as its drive mechanism, and includes, in addition to BEVs (Battery Electric Vehicles), PHEVs (Plug-in Hybrid Electric Vehicles), HEVs (Hybrid Electric Vehicles), and FCEVs (Fuel Cell Electric Vehicles).

[0003] However, in electric vehicles, many devices such as motors and batteries are housed in a limited space, requiring them to be laid out and have cooling piping installed through the gaps between these various devices.

[0004] Therefore, in order to increase the flexibility of cooling pipe layout or to facilitate installation, it is considered to use a resin pipe with corrugated sections having alternating peaks and valleys extending circumferentially along the pipe length as the cooling pipe. In such a resin pipe, bending deformation can be achieved by utilizing the expansion and contraction deformation in the corrugated sections, so by using it for cooling pipes, it is easy to achieve flexible layouts that connect limited spaces.

[0005] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2022-135796 Utility Model Content Problems to be solved by the utility model However, the inventors of this invention conducted detailed research on the stress analysis of resin pipes with corrugated sections using the finite element method. As a result, the following new problems were discovered: due to stress concentration in specific areas, it is sometimes difficult to ensure durability and reliability. For example, when further improving cooling performance, there are concerns that the problem of locally concentrated stress may worsen as the pressure of the cooling medium flowing inside the pipe increases.

[0006] Of course, such problems can be addressed by increasing the wall thickness of the resin tube to ensure durability and reliability. However, when solving the problem by increasing the wall thickness of the resin tube, it is impossible to avoid increasing costs and weight. In addition, the bending resistance in the corrugated part increases, which inevitably has an adverse effect on the layout and installation of cooling piping.

[0007] Here, the present invention provides a resin tube with a corrugated portion having a new shape feature as the problem to be solved, which can avoid the thickening of the tube wall by reducing or eliminating the concentration of local stress in the corrugated portion, and can improve the pressure resistance.

[0008] means for solving problems The following describes several aspects of the present invention used to solve such problems. Furthermore, the constituent elements employed in the various aspects described below can be combined arbitrarily within possible ranges. Additionally, it should be understood that the aspects or technical features of the present invention are not limited to the content described below, but are based on the inventive concept as described in the entire specification and drawings, or as can be understood by those skilled in the art from these descriptions.

[0009] The first aspect of this utility model is as follows.

[0010] A resin pipe body comprising a corrugated portion having alternating peaks and valleys extending circumferentially along its length, and used for cooling piping in electric vehicles, characterized in that... The radius of curvature Ra at the center of the outer surface of the valley is larger than the radius of curvature Rb at the center of the inner surface of the valley, and, The tube thickness in the valley section is greater than the tube thickness at the boundary between the peak section and the valley section.

[0011] The inventor of this invention conducted research and found that, in existing resin tubes, generally speaking, the radius of curvature of the inner surface at the valley is larger than that of the outer surface, while the thickness of the valley remains relatively constant throughout the entire tube. It was determined that in the aforementioned existing resin tube structure, stress generated on the tube wall due to internal pressure from the cooling medium tends to concentrate at approximately the central portion of the valley at the bottom of the corrugated section.

[0012] Therefore, in the resin tube body involved in this method, by making the radius of curvature Ra of the outer surface of the tube body larger than the radius of curvature Rb of the inner surface of the tube body at the valley bottom, the tube thickness at the center of the valley is ensured to be greater than that on both sides. It is thus determined that the stress generated at the valley bottom (the center of the valley) is dispersed to both sides, effectively reducing the stress generated.

[0013] Based on this, in the resin tube body involved in this method, the thickness of the valley is relatively large throughout the entire tube body compared to the tube thickness at the boundary between the peak and the valley. As a result, the stress dispersion at the bottom of the valley, achieved by Ra > Rb as described above, can be extended to a wider area of ​​the valley near the boundary with the peak.

[0014] Furthermore, according to this invention, a resin tube with a corrugated portion having such a novel valley shape feature is provided. By reducing local stress concentration at the valley, thickening of the tube wall can be avoided, and pressure resistance and durability can be improved. Therefore, for example, a resin tube for cooling electric vehicles can be achieved that effectively ensures the bending deformation characteristics and piping layout characteristics of the corrugated portion without a significant increase in cost or weight, and can also easily meet the requirements for improved pressure resistance.

[0015] Furthermore, in this embodiment, preferably, either the inner or outer surface of the corrugated portion of the resin tube is formed as a surface shape that smoothly connects the curved surface or the curved surface to a straight line without corners along the tube's length. This also helps to avoid deformation at corners, abrupt changes in stress, and stress concentration.

[0016] The second aspect of this utility model, based on the resin tube body involved in the first aspect, is characterized in that: The radius of curvature Ra at the center of the outer surface of the valley is infinite.

[0017] Furthermore, in this method, the radius of curvature Ra at the center of the outer surface of the valley is set to be infinitely large, thereby providing a straight valley surface extending for a predetermined length lv (≠0) in the tube length direction. On the other hand, the radius of curvature Rb at the center of the inner surface of the valley is formed as a non-straight curved surface according to the condition Ra > Rb.

[0018] The third aspect of this utility model, based on the resin tube body involved in the second aspect described above, is characterized in that... In the central portion of the outer surface of the valley, a straight valley surface extending in the tube length direction with a radius of curvature Ra of infinite magnitude extends on the outer surface for a length greater than 10% of the distance La between the inflection points on both sides of the boundary of the peak adjacent to both sides in the tube length direction.

[0019] The fourth aspect of this utility model, based on the resin tube body involved in any of the first to third aspects described above, is characterized in that: The distance between the boundary portions along the pipe length direction, i.e., the dimension between the boundary portions, is the distance on the central line of the pipe thickness connecting the center of the pipe thickness and the boundary portion corresponding to the inflection point of the boundary between the peak and the valley portion that are adjacent in the pipe length direction. The boundary dimension Lv between the valleys is larger than the boundary dimension Lm between the peaks.

[0020] Furthermore, in this method, the dimensions (Lm, Lv) between the peak-to-peak and valley-to-valley sections on the central line of the pipe thickness at the center of the connecting component thickness are set to Lm < Lv.

[0021] The fifth aspect of this utility model, based on the resin tube body involved in any of the first to fourth aspects described above, is characterized in that... The thickness of the tube in the valley is greatest at the center point of the outer surface and gradually decreases towards both sides in the direction of tube length.

[0022] The sixth aspect of this utility model, based on the resin tube body involved in any of the first to fifth aspects described above, is characterized in that... The radius of curvature Rc at the center of the outer surface of the peak is infinite.

[0023] Furthermore, in the resin tube body involved in this method, the radius of curvature Rc is set to be infinitely large at the center of the outer surface of the peak, thereby providing a flat surface of the peak extending for a predetermined length lm (≠0) in the tube length direction.

[0024] The seventh aspect of this utility model, based on the resin tube body involved in the sixth aspect, is characterized in that: The radius of curvature Rd at the center of the inner surface of the peak is a finite number.

[0025] The eighth aspect of this utility model, based on the resin tube body involved in the sixth or seventh aspect described above, is characterized in that: At the center of the outer surface of the valley, a straight valley surface extending with a length lv in the tube length direction is provided by making the radius of curvature Ra infinitely large. The length lv of the valley flat surface (40) is set in the range of 100% to 140% of the length lm, relative to the length lm of the peak flat surface (42) which extends in the tube length direction by making the radius of curvature Rc infinitely large at the center of the outer surface of the peak (20).

[0026] The ninth aspect of this utility model, based on the resin tube body involved in any of the first to eighth aspects described above, is characterized in that... The resin tube body has a straight section extending with a constant inner and outer diameter at a position offset from the corrugated portion along the tube length direction. The smallest inner diameter of the pipe at the valley section is smaller than the inner diameter of the pipe in the straight section.

[0027] The tenth aspect of this utility model, based on the resin tube body involved in any of the first to ninth aspects described above, is characterized in that... The resin tube body has straight tube sections extending with constant inner and outer diameters on both sides of the corrugated section along its length. The peaks are provided at the connection ends of the corrugated sections on both sides of the length direction of the corrugated section and each of the straight pipe sections.

[0028] The eleventh aspect of this utility model, based on the resin tube body involved in any of the first to tenth aspects described above, is characterized in that: The resin tube body has a straight section extending with a constant inner and outer diameter at a position offset from the corrugated portion along the tube length direction. Compared to the pipe thickness Ts of the straight pipe section, the pipe thickness Tc of the corrugated section extends throughout the entire corrugated section and satisfies 50% ≦ Tc < 100%.

[0029] That is, in the resin tube body involved in this method, the tube thickness Tc of the corrugated part is 0.5Ts≦Tc<1.0Ts relative to the tube thickness Ts of the straight part.

[0030] The twelfth aspect of this utility model, based on the resin tube body involved in any of the first to eleventh aspects described above, is characterized in that... On the center line of the pipe thickness in the center of the connecting pipe, The minimum value of the radius of curvature rv at the valley is greater than the minimum value of the radius of curvature rm at the peak.

[0031] Utility Model Effect According to this invention, stress can be dispersed to both sides at the valley where stress concentration is identified, thereby reducing stress. As a result, a resin tube for cooling electric vehicles can be made that effectively ensures the bending deformation characteristics in the corrugated section and easily meets the requirements for improved pressure resistance. Attached Figure Description

[0032] Figure 1 This is a schematic diagram showing the overall structure of the resin tube body as one embodiment of the present invention.

[0033] Figure 2 yes Figure 1 Enlarged view of section II-II of the resin tube shown.

[0034] Figure 3 yes Figure 2 Enlarged illustration of Part III.

[0035] Figure 4 yes Figure 3 The diagram shows the stress distribution in the resin tube under internal pressure.

[0036] Figure 5 This is a stress distribution diagram of a comparative example of a resin tube under internal pressure.

[0037] Explanation of reference numerals in the attached figures 10: Resin pipe body; 12: Rippled section; 14: Straight pipe section; 20: Peak; 22: Tanibe; 26: Inner surface of the pipe; 28: Outer surface of tube; 30: Pipe thickness centerline; 32: Pipe center axis; 34: Boundary section; 40: Flat surface of the valley; 42: The peak is flat and straight; Ra: Radius of curvature at the center of the outer surface of the valley; Rb: Radius of curvature at the center of the inner surface of the valley; Ba: Inflection point on the outer surface of the tube; Bb: Inflection point on the inner surface of the pipe; Bc: Inflection point on the center line of the pipe thickness; La: the distance between Ba and Ba adjacent to each other in the valley; Ps: The center point of the outer surface of the valley; Tv: Thickness of the tube in the valley section; Tm: Pipe thickness at the peak; Ts: Pipe thickness of the straight section (constant); Tc: Pipe thickness of the corrugated section (Tv and Tm); lv: Length of the flat surface at the valley level; lm: Length of the flat surface of the peak; Ds: Inner diameter of the straight section of the pipe; Dc: Inner diameter of the corrugated section. Detailed Implementation

[0038] The embodiments of this utility model will now be described with reference to the accompanying drawings.

[0039] First of all, Figure 1 The resin tube 10, as an embodiment of the present invention, is shown in its overall appearance from the side. This resin tube 10 serves as piping for a cooling device in an electric vehicle, for example, as a component forming a refrigerant flow path in a battery cooling system.

[0040] The resin tube 10 described above has a corrugated portion 12 located in the middle of its length and extending for a predetermined length. Straight tube portions 14, extending with constant inner and outer diameters, are integrally formed on both sides of the corrugated portion 12 in the length direction. Furthermore, the diameter and length dimensions of the corrugated portion 12 and the straight tube portions 14 are not limited and can be appropriately set according to the performance requirements and flow path shape of each vehicle used. Additionally, the corrugated portion 12 may be spaced apart at multiple locations along the length direction of the resin tube 10, sandwiching the straight tube portions 14.

[0041] The material of the resin tube 10 is not limited, and various resin materials can be used, taking into account the refrigerant used and environmental conditions such as temperature under operating conditions. For example, general-purpose resins such as polypropylene resins and polyamide resins can be used, as well as vinyl alcohol resins such as EVOH. It is not limited to a single-layer structure, but can also be a multi-layered stacked structure.

[0042] Here, the corrugated portion 12 is formed as a structure in which peaks 20 and valleys 22, which extend in a constant cross-sectional shape in the circumferential direction, are alternately and continuously arranged in the longitudinal direction of the tube. That is, the peaks 20 have a cross-sectional shape that protrudes on the outer peripheral surface, and the valleys 22 have a cross-sectional shape that is recessed on the outer peripheral surface.

[0043] Furthermore, these peaks 20 and valleys 22 are all formed such that, regardless of whether they are on the inner surface 26 or the outer surface 28, they have no bends in the tube length direction (left-right direction in the figure). That is, even at points with different inclination angles, they are connected by a common tangent and have a smooth, continuous curved surface shape. In particular, in this embodiment, they are formed into a surface shape that smoothly connects curves and straight lines. Furthermore, the tube thickness centerline 30 connecting the center of the tube thickness is also formed into a smooth, continuous curved shape that extends throughout the entire tube length direction connecting the peaks 20 and valleys 22 without any bends. In particular, in this embodiment, it is formed into a shape that smoothly connects curves and straight lines.

[0044] Furthermore, these peaks 20 and valleys 22 have the specific shapes described below.

[0045] (1) The radius of curvature Ra of the center of the outer surface of the valley 22 is larger than the radius of curvature Rb of the center of the inner surface of the valley 22. That is, Ra > Rb.

[0046] Furthermore, since Ra and Rb are the radii of curvature of the valley 22, it is envisioned that the resin tube 10 has a center of curvature on the outer side of the valley 22 (the side opposite to the central axis 32), and this center is set towards the central axis 32 of the resin tube 10 (see reference). Figure 2 The positive value is taken in the direction of the convex shape inside the tube where the location is located, and negative values ​​are not taken.

[0047] (2) The thickness of the valley 22 is set to be greater than the thickness of the boundary 34 between the peak 20 and the valley 22. That is, the valley 22, which has a shape that protrudes toward the inside of the tube, has the smallest thickness at both ends of the valley 22, i.e., at the boundary 34, and is formed with a thickness greater than that at both ends throughout the entire valley 22.

[0048] Furthermore, the boundary portion 34 can be objectively defined as the inflection point between the peak portion 20 protruding outwards from the tube body and the valley portion 22 recessed inwards from the tube body. That is, the tube thickness passing through the inflection point Bc on the tube thickness centerline 30 is the tube thickness of the boundary portion 34. Generally speaking, the inflection point Bc can also be understood as the midpoint on the straight line connecting the inflection point Ba of the outer surface 28 and the inflection point Bb of the inner surface 26.

[0049] Moreover, by combining the characteristics of the shapes described in (1) and (2) above, the large stress that is easily generated at the bottom of the valley (the central part of the valley 22) can be dispersed to a wide range on both sides, thereby reducing the stress. By reducing the local stress concentration at the valley 22, the thickening of the resin tube 10 can be avoided and the pressure resistance and durability can be improved.

[0050] (3) The radius of curvature Ra at the center of the outer surface of the valley 22 is infinite (∞). That is, in this method, a point is provided at the center of the outer surface of the valley 22 in the direction of tube length ( Figure 3 The valley 22 is a straight surface 40 extending with a predetermined length lv (≠0) in the left-right direction. In addition, the radius of curvature Rb at the center of the inner surface of the valley 22 is formed as a non-straight curved surface according to the condition Ra>Rb described in (1) above.

[0051] By adopting the shape characteristics described above (3) and setting a flat valley surface 40 in the center of the outer surface of the valley 22, the pressure resistance of the valley can be improved more effectively, and the degree of thickness variation of the bottom central part of the valley 22 in the tube length direction can be easily designed by the radius of curvature Rb of the inner surface 26.

[0052] (4) The valley flat surface 40 of the length lv described in (3) above is formed to have a length extending on the outer surface 28 of the tube as follows: a length of more than 10% of the straight distance La between the inflection points Ba on both sides of the peak 20 adjacent to the two sides in the tube length direction and the boundary of the peak 20.

[0053] Furthermore, an inflection point refers to the point where the center of curvature is located on the opposite side, that is, the point where the sign of the second derivative of the function representing the shape of the tube's outer surface 28 along its length changes. Additionally, when the boundary between the peak 20 and the valley 22 extends along a straight line formed by a linear function inclined relative to the tube's central axis 32, the center of the length direction of this straight line is taken as the inflection point.

[0054] By adopting the shape characteristics described above (4), the length of the flat surface of the valley can be ensured, and the effect of improving the compressive strength of the valley as described above (3) can be further improved.

[0055] (5) Regarding the dimension between the boundary between the peak 20 and the valley 22 on the central line 30 of the tube thickness, the dimension Lv between the boundary between the valley 22 and the peak 20 is larger than the dimension Lm between the boundary between the peak 20 and the valley 22. That is, Lm < Lv.

[0056] By adopting the shape characteristics described above (5), the dimensions (Lm, Lv) between the peak-to-peak and valley-to-valley boundaries on the tube thickness centerline 30 are Lm < Lv, which advantageously ensures the tube length dimension at the valley 22. Therefore, in the valley 22, where stress tends to increase compared to the peak 20, a wider area of ​​stress generation can be dispersed in the tube length direction, further improving durability, etc. Moreover, since it is a small diameter, even in the valley 22 where deformation rigidity tends to increase, flexibility or ease of bending deformation can be improved by increasing the tube length. Furthermore, in the dimensions between the boundaries Ba and Ba on the outer surface 28 of the resin tube body 10, the dimensions between the boundaries on both sides sandwiching the peak 20 and the dimensions between the boundaries on both sides sandwiching the valley 22 can be approximately the same.

[0057] (6) The thickness Tv of the valley 22 is the largest at the center point Ps of the outer surface in the direction of the tube axis, and gradually decreases from the center point Ps of the outer surface towards both sides in the direction of tube length. In addition, the thickness Tv of the valley 22 is the tube wall thickness dimension in the direction orthogonal to the tube wall at the valley 22. Generally speaking, it is the tube wall thickness dimension in the direction orthogonal to the inner surface 26 or the outer surface 28 of the tube.

[0058] By adopting the shape characteristics described above (6), the tube thickness at the central point Ps of the outer surface where stress is most likely to concentrate in the valley 22 can be ensured to be large, thereby more effectively ensuring pressure resistance and durability. In addition, by making the tube thickness of the valley 22 gradually decrease from the central point Ps of the outer surface towards both sides in the tube length direction, it is possible to avoid excessive deformation rigidity at the valley 22, and it is also easier to ensure the bending deformation performance in the corrugated part 12.

[0059] (7) The radius of curvature Rc at the center of the outer surface 28 of the peak 20 is infinite (∞). That is, in this embodiment, a radius of curvature Rc at the center of the outer surface of the peak 20 in the tube length direction is provided. Figure 3 A flat surface 42 of the peak extending 1m (≠0) in the left-right direction of the middle.

[0060] By adopting the shape characteristics described above (7), for example, stress concentration at the peak can be avoided by suppressing local thinning at the central part of the peak 20, and the bending deformation characteristics at the peak can be further improved.

[0061] (8) The radius of curvature Rd at the center of the inner surface of the peak 20 is a finite number.

[0062] By adopting the shape characteristics described in (8), the thickness of the peak 20 can be adjusted by the shape of the inner circumferential surface. For example, excessive rigidity at the peak 20 can be suppressed, thereby further improving the bending deformation characteristics of the corrugated portion 12. In particular, by combining this with the method described in (7), the inner surface of the peak 20 corresponding to the flat surface 42 of the outer surface is made into a curved surface protruding outward from the tube body. Thus, at least in the portion where the flat surface 42 is formed, the tube thickness Tm of the peak 20 is minimum at the center point of the outer surface and gradually increases towards both sides in the tube length direction. As a result, deformation and stress dispersion at the central part of the peak 20 can also be achieved.

[0063] Furthermore, since Rc and Rd are the radii of curvature of the peak 20, it is envisioned that the resin tube 10 has a center of curvature on the inner side of the peak 20 (the side where the central axis 32 is located), and that positive values ​​are taken in the direction of the tube body convex towards the outer side of the tube body on the side opposite to the central axis 32 of the resin tube 10, and negative values ​​are not taken.

[0064] (9) A peak flat surface 42 described in (7) is provided on the outer surface of the peak 20 with a length of lm, and the radius of curvature Ra at the center point Ps of the outer surface of the valley 22 is infinitely large. Thus, a valley flat surface 40 extending with a length of lv in the tube length direction is provided. The length lv of the valley flat surface 40 is set in the range of 100% to 140% of the length lm of the peak flat surface.

[0065] By adopting the shape characteristics described above (9), the length lm of the peak flat surface 42 and the length lv of the valley flat surface 40 are formed with relatively close lengths. As a result, it is possible to combine and more effectively enjoy the improved pressure resistance and durability brought about by the stress dispersion at the peak 20 and valley 22, and also to achieve good improvement in bending deformation characteristics, etc.

[0066] (10) The minimum value of the inner diameter Ds of the straight pipe portion 14 extending with a constant inner and outer diameter at a position away from the corrugated portion 12 in the pipe length direction is smaller than the minimum inner diameter of the central portion of the corrugated portion 12.

[0067] By employing the shape characteristics described above (10), even when a straight pipe with a constant inner and outer diameter is pre-formed using a known forming method such as extrusion, and a predetermined length portion in the pipe length direction is deformed by heat or the like to form a corrugated portion 12, the thickness Tc of the valley 22 in the corrugated portion 12 can be largely ensured by making the minimum inner diameter of the valley 22 in the corrugated portion 12 smaller than the inner diameter Ds of the straight pipe portion 14. As a result, pressure resistance and durability are further improved by ensuring the thickness of the valley 22, where stress is easily concentrated.

[0068] In particular, the molding method of the resin tube body 10 involved in this utility model is not limited. For example, in the extrusion molding of a straight tube obtained in advance as described above, for the straight tube that has just been extruded, the outer mold surrounding the outer peripheral surface in the thermoplastic state is continuously overlapped. While the outer peripheral surface of the straight tube is attracted to the molding surface of the outer mold by using negative pressure, the corrugated shape formed on the molding surface of the outer mold is transferred and attached, thereby continuously forming the corrugated portion 12 for the purpose in the tube length direction.

[0069] Preferably, the straight tube 10 is extruded using the inner and outer diameter dimensions of the straight tube portion 14 of the resin tube body 10 for the intended purpose. Relative to the inner diameter Ds of the straight tube portion 14, the inner diameter Dc of the corrugated portion 12 is smaller at the valley 22 (Ds > Dc), and larger at the peak 20 (Dc < Dm). Furthermore, regarding the thickness of the peripheral wall of the resin tube body 10, relative to the thickness Ts of the straight tube portion 14, the thickness Tc of the corrugated portion 12 is smaller than Ts at both the valley 22 and the peak 20 (Tc ≦ Ts). More preferably, the thickness Tc of the corrugated portion 12 is smaller than the thickness Ts of the straight tube portion 14 over its entire length, excluding the connection points with the straight tube portion 14 at both ends in the longitudinal direction (Tc < Ts).

[0070] (11) The corrugated portion 12 has a straight pipe portion 14 extending with a constant inner and outer diameter on both sides of the length direction. A peak portion 20 is provided at the connection end of each straight pipe portion 14 on both sides of the length direction of the corrugated portion 12.

[0071] By adopting the shape characteristics described above (11), the stress concentration at the valley can be more effectively reduced when the corrugated portion 12 is bent and deformed according to the piping configuration of the vehicle. That is, when the corrugated portion 12 is bent in accordance with the piping space, the stress is easily concentrated at both ends of the corrugated portion 12 in the pipe length direction due to the deformation restraint force caused by the straight pipe portion 14 with high deformation rigidity. Therefore, by arranging the peak portion 20, which is easier to bend and deform than the valley portion 22 and easier to suppress stress generation, in the above-mentioned portion (both ends of the corrugated portion 12 in the pipe length direction), the stress generated at the corrugated portion 12 can be reduced, and the bending performance of the corrugated portion 12 can be improved. Moreover, by arranging the valley portion 22 in a way that avoids the connection end of the corrugated portion 12 with the straight pipe portion 14, the stress generated in the valley portion 22 during bending of the piping can be further effectively reduced in combination with the stress dispersion effect of the valley portion 22 based on the shape of the present invention as described above.

[0072] (12) A straight pipe portion 14 extending with a constant inner and outer diameter is provided at a position offset from the corrugated portion 12 in the pipe length direction. The pipe thickness Ts of the corrugated portion 12 satisfies 50% ≦ Tc < 100% over the entire corrugated portion.

[0073] In the resin tube 10 with the shape characteristics described above (12), the tube thickness Tc of the corrugated portion 12 is 0.5Ts≦Tc<1.0Ts relative to the tube thickness Ts of the straight portion 14. This, combined with the stress dispersion effect of the valley 22 based on the shape of the valley 22 of the present invention as described above, avoids the thickening of the corrugated portion 12 and achieves good deformation characteristics, and can further effectively improve the pressure resistance and durability of the corrugated portion 12.

[0074] Furthermore, in the corrugated portion 12, the position where the pipe thickness Tc is minimum is preferably set at the central portion of the peak portion 20. Conversely, in the corrugated portion 12, the position where the pipe thickness Tc is maximum is preferably set at the central portion of the valley portion 22. This allows for a more convenient balance between improving pressure resistance and durability at the valley portion 22, where stress concentration is more likely, and ensuring good bending deformation characteristics at the peak portion 20, where stress concentration is less likely to occur compared to the valley portion 22.

[0075] (13) On the central line 30 of the pipe thickness in the middle of the connecting pipe thickness, the minimum value of the radius of curvature rv at the valley 22 is greater than the minimum value of the radius of curvature rm at the peak 20.

[0076] In the resin tube 10 with the shape characteristics described above (13), stress can be more effectively dispersed over a wide range at the valley 22 where stress concentration is prone to become a problem, and buckling deformation can also be prevented. On the other hand, bending deformation characteristics can be further improved at the peak 20.

[0077] Incidentally, the shape formed according to the characteristics described in (1) to (13) above will be used. Figures 1-3 The resin tube 10 of this embodiment, as described in the text, is used to simulate the stress distribution generated by the pressure action inside the tube, and is shown as an example. Figure 4 Furthermore, simulation results of stress distribution obtained under the same conditions for a conventional resin tube body with a structure that does not possess the shape characteristics described above (1), etc., are presented as a comparative example. Figure 5 Furthermore, in both the examples and comparative examples, the resin tube was made of a single-layer polypropylene structure, and simulations were conducted under atmospheric pressure with an internal tube pressure of 120 kPa.

[0078] According to these Figure 4 , Figure 5 The simulation results shown are in Figure 4 In the embodiments shown, almost no trace of Figure 5 The comparative example shown illustrates areas of varying density observed in the valley. Furthermore, based on specific calculation results, in... Figure 4 In the illustrated embodiment, the maximum stress value generated in the valley can be suppressed to Figure 5 The comparative example shown is less than 70%. Based on this, it can be confirmed that stress dispersion has been achieved, particularly in the valleys where stress tends to concentrate.

[0079] The above describes in detail the specific and preferred embodiments of the present invention, but the present invention should not be interpreted in a limited way based on the specific descriptions and methods described above. In particular, the shape features described in (3) to (13) above are preferred in the present invention, but can be used arbitrarily, not necessarily.

[0080] For example, the specific length, thickness, radius of curvature, and other dimensions of each part, including the gaps between the peaks 20 and valleys 22 in the corrugated section 12, need to be appropriately designed in addition to taking into account the required characteristics of the resin tube body 10, such as pressure resistance and bending performance, and also need to take into account the inner and outer diameters, etc., and are not limited.

[0081] In addition, in the above embodiments, a peak portion 20 is provided at the end of the corrugated portion 12, which serves as the connection to the straight pipe portion 14, in the pipe length direction. However, a valley portion 22 may also be provided at either end or at both ends.

[0082] Furthermore, the maximum thickness Tc at the corrugated portion 12 is preferably within 200% of the minimum thickness. Generally speaking, relative to the minimum thickness Tvmin at the valley portion 22, the maximum thickness Tmmax at the peak portion 20 is preferably Tmmax ≤ 200%. Tvmin.

[0083] In addition, the flat surface 42 of the peak 20 is not necessary, and the outer surface 28 of the tube of the peak 20 can be curved all over.

[0084] Furthermore, although not listed one by one, this utility model can be implemented with various changes, modifications, improvements, etc. based on the knowledge of those skilled in the art. Moreover, needless to say, these implementation methods are all included within the scope of this utility model without departing from its spirit.

Claims

1. A resin pipe body (10) comprising a corrugated portion (12) having alternating peaks (20) and valleys (22) extending circumferentially in the pipe length direction, and used for cooling piping in electric vehicles, characterized in that, The radius of curvature Ra at the center of the outer surface of the valley (22) is larger than the radius of curvature Rb at the center of the inner surface of the valley (22), and, The thickness of the tube in the valley (22) is greater than the thickness of the tube in the boundary (34) between the peak (20) and the valley (22).

2. The resin tube body (10) according to claim 1, characterized in that, The radius of curvature Ra at the center of the outer surface of the valley (22) is infinite.

3. The resin tube body (10) according to claim 2, characterized in that, In the central portion of the outer surface of the valley (22), a valley straight surface (40) extending in the tube length direction with a radius of curvature Ra of infinitely large extends on the outer surface with a length of more than 10% of the distance between the inflection points on both sides of the boundary of the peak (20) adjacent to both sides in the tube length direction.

4. The resin tube body (10) according to claim 1 or 2, characterized in that, The distance between the boundary portions along the pipe length direction, i.e., the dimension between the boundary portions, is the distance on the pipe thickness centerline (30) at the center of the pipe thickness that corresponds to the inflection point of the boundary between the peak portion (20) and the valley portion (22) that are adjacent in the pipe length direction. The boundary dimension Lv between the valley (22) and the peak (20) is larger than the boundary dimension Lm between the valley (22) and the peak (20).

5. The resin tube body (10) according to claim 1 or 2, characterized in that, The thickness of the valley (22) is greatest at the center point of the outer surface and gradually decreases towards both sides in the direction of tube length.

6. The resin tube body (10) according to claim 1 or 2, characterized in that, The radius of curvature Rc at the center of the outer surface of the peak (20) is infinite.

7. The resin tube body (10) according to claim 6, characterized in that, The radius of curvature Rd at the center of the inner surface of the peak (20) is a finite number.

8. The resin tube body (10) according to claim 6, characterized in that, At the center of the outer surface of the valley (22), a valley straight surface (40) extending with a length lv in the tube length direction is provided by making the radius of curvature Ra infinite. The length lv of the valley flat surface (40) is set in the range of 100% to 140% of the length lm, relative to the length lm of the peak flat surface (42) which extends in the tube length direction by making the radius of curvature Rc infinitely large at the center of the outer surface of the peak (20).

9. The resin tube body (10) according to claim 1 or 2, characterized in that, The resin tube body (10) has a straight tube portion (14) extending with a constant inner and outer diameter at a position offset from the corrugated portion (12) in the tube length direction. The smallest inner diameter of the tube at the valley section (22) is smaller than the inner diameter of the tube at the straight section (14).

10. The resin tube body (10) according to claim 1 or 2, characterized in that, The resin tube body (10) has straight tube portions (14) extending with constant inner and outer diameters on both sides of the corrugated portion (12) along its length. The peak (20) is provided at the connection end of each straight pipe section (14) on both sides of the length direction of the corrugated section (12).

11. The resin tube body (10) according to claim 1 or 2, characterized in that, The resin tube body (10) has a straight tube portion (14) extending with a constant inner and outer diameter at a position offset from the corrugated portion (12) in the tube length direction. The thickness Ts of the corrugated part (12) is Tc, which is relative to the thickness Ts of the straight part (14), and the thickness Tc of the corrugated part (12) is Tc throughout the entire corrugated part (12) and satisfies 50% ≦ Tc < 100%.

12. The resin tube body (10) according to claim 1 or 2, characterized in that, On the center line (30) of the pipe thickness in the center of the connecting pipe thickness, The minimum value of the radius of curvature rv at the valley (22) is greater than the minimum value of the radius of curvature rm at the peak (20).

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