Grommet and wire harness with grommet
Patent Information
- Application Number
- PCT/JP2026/015041
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-04-17
- Filing Date
- 2026-04-13
- Publication Date
- 2026-10-22
Smart Images
Figure JP2026015041_22102026_PF_FP_ABST
Abstract
Description
Grommet and wire harness with grommet
[0001] The present disclosure relates to a grommet and a wire harness with a grommet.
[0002] Patent Document 1 discloses an automotive grommet that includes a pair of mounting portions, and a bellows-shaped hollow cylindrical portion that integrally connects the pair of mounting portions via respective elbow-shaped portions, wherein a spiral portion having continuous spiral crests and troughs is formed on the bellows-shaped hollow cylindrical portion. Such a grommet is mounted between a door and a vehicle body. Further, the bellows-shaped hollow cylindrical portion is intended to improve followability to the twisting action applied to the grommet during door opening and closing, and to also improve durability and waterproof performance.
[0003] Japanese Unexamined Patent Application Publication No. 2007-157495
[0004] It is desired that a grommet including a spiral bellows cylindrical portion be easy to manufacture using a mold.
[0005] Accordingly, an object of the present disclosure is to provide a technique that facilitates the manufacture of a grommet including a spiral bellows cylindrical portion using a mold.
[0006] The grommet of the present disclosure is a grommet formed by a mold having a plurality of outer molds and at least one inner mold, comprising a cylindrical portion including a helical bellows cylindrical portion, the helical bellows cylindrical portion having peaks and valleys that extend helically around the axis of the cylindrical portion, the outer surface of the helical bellows cylindrical portion having a plurality of dividing lines formed along the axial direction of the cylindrical portion as traces of the plurality of outer molds, the plurality of dividing lines having a first dividing line and a second dividing line adjacent to the first dividing line along the circumferential direction of the helical bellows cylindrical portion, the helical bellows cylindrical portion having a first portion located between the first dividing line and the second dividing line in the circumferential direction, and in a cross section perpendicular to the axial direction, the first portion The grommet is such that the direction connecting the secant line and the second dividing line is defined as the first direction, the direction perpendicular to the first direction is defined as the second direction, the first portion has an outer surface portion extending from the first dividing line and the second dividing line, and an inner surface portion opposite to the outer surface portion, the innermost portion of the outer surface portion located furthest inward along the first direction is defined as the innermost portion, the outermost portion of the inner surface portion located furthest outward along the first direction is defined as the outermost portion, and in the first portion, at any position along the axial direction, there is no undercut shape, or if there is an undercut shape, the innermost portion is located further outward along the first direction than the outermost portion in the portion having an undercut shape.
[0007] According to this disclosure, grommets including a helical bellows section can be easily manufactured using a mold.
[0008] Figure 1 is a perspective view showing a grommet according to Embodiment 1. Figure 2 is a cross-sectional view along line II-II in Figure 1. Figure 3 is a cross-sectional view along line III-III in Figure 1. Figure 4 is a cross-sectional view showing the process of forming the helical bellows portion. Figure 5 is a cross-sectional view showing the process of forming the helical bellows portion. Figure 6 is a cross-sectional view showing the process of forming the helical bellows portion. Figure 7 is an enlarged view of region R1 in Figure 5. Figure 8 is a cross-sectional view showing a grommet according to Embodiment 2. Figure 9 is a cross-sectional view showing the process of forming the helical bellows portion. Figure 10 is a cross-sectional view showing the process of forming the helical bellows portion of a grommet according to Reference Example 1. Figure 11 is a cross-sectional view showing the process of forming the helical bellows portion of a grommet according to Reference Example 2.
[0009] [Description of Embodiments of the Disclosure] First, embodiments of the Disclosure will be listed and described.
[0010] The grommets of this disclosure are as follows:
[0011] (1) A grommet formed by a mold having a plurality of outer molds and at least one inner mold, comprising a cylindrical portion including a helical bellows cylindrical portion, the helical bellows cylindrical portion having peaks and valleys extending helically around the axis of the cylindrical portion, a plurality of dividing lines formed on the outer surface of the helical bellows cylindrical portion as traces of the plurality of outer molds being removed along the axial direction of the cylindrical portion, the plurality of dividing lines having a first dividing line and a second dividing line adjacent to the first dividing line along the circumferential direction of the helical bellows cylindrical portion, the helical bellows cylindrical portion having a first portion located between the first dividing line and the second dividing line in the circumferential direction, and in a cross section perpendicular to the axial direction, the first dividing line and the front The grommet is such that the direction connecting the first dividing line and the second dividing line is defined as the first direction, the direction perpendicular to the first direction is defined as the second direction, the first part has an outer surface portion extending from the first dividing line and the second dividing line, and an inner surface portion opposite to the outer surface portion, the innermost part of the outer surface portion located furthest inward along the first direction is defined as the innermost part, and the outermost part of the inner surface portion located furthest outward along the first direction is defined as the outermost part, and in the first part, at any position along the axial direction, there is no undercut shape, or if there is an undercut shape, the innermost part is located further outward along the first direction than the outermost part in the portion having an undercut shape.
[0012] According to the grommet in (1), in the first part, at any position along the axial direction, there is no undercut shape, or if there is an undercut shape, the innermost part of the part with the undercut shape is located outward in the first direction from the outermost part, thereby suppressing contact between the outer mold and the inner mold when removing the mold.
[0013] (2) In the grommet of (1), the plurality of dividing lines have three or more dividing lines, and the first portion does not have to have an undercut shape at any position along the axial direction. This makes it possible to suppress interference between the outer mold and the grommet when the outer mold is removed.
[0014] (3) In the grommet of (1), the first portion has an undercut shape at least in part along the axial direction, and the distance between the innermost portion and the outermost portion in the first direction at the position having the undercut shape may be 30% or more of the thickness of the helical bellows cylinder portion. Because the first portion has an undercut shape on its outer surface, the outer mold and the grommet interfere when the outer mold is removed. Even in this case, the outer mold can be removed by the elasticity of the grommet. By having the distance between the innermost portion and the outermost portion in the first direction be 30% or more of the thickness of the helical bellows cylinder portion, it is possible to prevent the distance between the outer mold and the inner mold from becoming too small when the outer mold is removed.
[0015] (4) In any one of the grommets from (1) to (3), the number of peaks along the circumferential direction of the helical bellows tube may be twice or more the number of dividing lines. This increases the number of peaks included in one outer mold, and reduces the number of outer molds.
[0016] (5) In the grommet of (4), the number of peaks along the circumferential direction of the helical bellows cylinder portion may be an integer multiple of the number of dividing lines. This makes it possible to make the shape of the portion forming the helical bellows cylinder portion the same among the multiple outer molds.
[0017] (6) The grommeted wire harness of the present disclosure is a grommeted wire harness comprising one grommet from (1) to (5) and a wire harness passed through the cylindrical portion of the grommet.
[0018] [Details of Embodiments of the Disclosure] Specific examples of grommets and wire harnesses with grommets of the Disclosure are described below with reference to the drawings. However, the Disclosure is not limited to these examples and is intended to include all modifications within the meaning and scope of the equivalents of the claims, as indicated by the claims.
[0019] In each drawing, some parts of the configuration may be exaggerated or simplified for ease of explanation. Also, the dimensional ratios of each part may differ in each drawing. Furthermore, in this specification, "parallel" and "orthogonal" do not only refer to strictly parallel or orthogonal connections, but also to connections that are approximately parallel or orthogonal within the range that achieves the function and effect of this embodiment.
[0020] In this disclosure, the three mutually orthogonal directions are defined as the X direction, the Y direction, and the Z direction. One side of the X direction is designated as the X1 direction, and the other side as the X2 direction. One side of the Y direction is designated as the Y1 direction, and the other side as the Y2 direction. One side of the Z direction is designated as the Z1 direction, and the other side as the Z2 direction. In each drawing, the X1 direction, X2 direction, Y1 direction, Y2 direction, Z1 direction, and Z2 direction are shown.
[0021] [Embodiment 1] Hereinafter, a grommet and a wire harness with a grommet according to Embodiment 1 will be described. Figure 1 is a perspective view showing a grommet 10 according to Embodiment 1. Figure 2 is a cross-sectional view along the line II-II in Figure 1. Figure 3 is a cross-sectional view along the line III-III in Figure 1. Figures 4 to 6 are cross-sectional views showing the process of forming the helical bellows cylinder portion 20. The cross-section in Figure 4 corresponds to the cross-section at the position along the line IV-IV in Figure 3. The cross-section in Figure 5 corresponds to the cross-section at the position along the line V-V in Figure 3. The cross-section in Figure 6 corresponds to the cross-section at the position along the line VI-VI in Figure 3. Figure 7 is an enlarged view of region R1 in Figure 5.
[0022] The grommet 10 includes a cylindrical portion 12 through which a wire harness 82 passes. The cylindrical portion 12 has an outer surface 13 and an inner surface 14. In this embodiment, the axial direction of the cylindrical portion 12 is along the X direction. Two directions perpendicular to the axial direction of the cylindrical portion 12 are along the Y direction and the Z direction. In the grommet 10, as shown in Figure 2, the cross section along the axial direction of the cylindrical portion 12 is a longitudinal cross section, and as shown in Figure 3, the cross section perpendicular to the axial direction of the cylindrical portion 12 is a transverse cross section. In this embodiment, the grommet 10 includes a wiring fixing portion 50. The wiring fixing portion 50 may be omitted. The grommet 10 is formed from an elastic material such as rubber or elastomer. The grommet 10 is, for example, an injection molded product using a mold M.
[0023] The cylindrical portion 12 includes a helical bellows cylindrical portion 20. The helical bellows cylindrical portion 20 is a cylindrical portion in which bellows sections having peaks 21 and valleys 22 extend helically around the axis of the cylindrical portion 12. In this disclosure, the convex portions on the outer surface 13 are referred to as peaks 21, and the concave portions on the outer surface 13 are referred to as valleys 22. On the inner surface 14, the convex-concave relationship of the peaks 21 and valleys 22 is reversed compared to the outer surface 13. That is, on the inner surface 14, the peaks 21 are concave and the valleys 22 are convex.
[0024] In the helical bellows section 20, multiple sets of peaks 21 and valleys 22 are arranged in a spiral pattern parallel to each other. For example, the number of sets of peaks 21 and valleys 22 is not particularly limited, but may be, for example, 5 to 25 sets. The number of sets of peaks 21 and valleys 22 may be even or odd. Here, 12 sets of peaks 21 and valleys 22 extend spirally around the cylindrical section 12 in parallel to each other, forming the helical bellows section 20. As shown in Figure 3, in the cross-section of the helical bellows section 20, the 12 sets of peaks 21 and valleys 22 are arranged alternately in the circumferential direction.
[0025] The number of times the peaks 21 and valleys 22 circle around the cylindrical portion 12 from one end to the other of the helical bellows cylindrical portion 20 is not particularly limited and can be set as appropriate. Here, the number of times the peaks 21 and valleys 22 circle around the helical bellows cylindrical portion 20 from one end to the other is about half a turn. In the longitudinal section of Figure 2, the peaks 21 are the peaks 21 of adjacent grooves. When the number of peaks 21 aligned axially in the longitudinal section of Figure 2 exceeds the number of peaks 21 aligned circumferentially in the cross section of Figure 3, the peaks 21 complete one full circle around the cylindrical portion 12. In this embodiment, since the number of peaks 21 in the cross section of Figure 3 is 12, when the number of peaks 21 aligned axially in the longitudinal section of Figure 2 exceeds 12, the peaks 21 complete one full circle around the cylindrical portion 12. For example, in the longitudinal section of Figure 2, if there are 13 peaks 21 aligned in the axial direction, the first peak 21 and the thirteenth peak 21 are the same peak 21.
[0026] The depth from the peak 21 to the valley 22 is not particularly limited and can be set as appropriate. The depth from the peak 21 to the valley 22 can also be considered as the radial distance between the peak 21 and the valley 22. Alternatively, the depth from the peak 21 to the valley 22 can be considered as the difference between the outer diameter OD at the peak 21 and the inner diameter ID at the valley 22. In Figure 3, dimension OD represents the outer diameter from the center of the helical bellows cylinder 20 to the outer surface 13 of the peak 21. Dimension ID represents the inner diameter from the center of the helical bellows cylinder 20 to the inner surface 14 of the valley 22. Dimension G represents the difference between dimension OD and dimension ID. Dimension G is an indicator of the depth from the peak 21 to the valley 22. As will be described in more detail later, the shallower the depth from the peak 21 to the valley 22, the easier it is to manufacture the grommet 10.
[0027] In this embodiment, the cylindrical portion 12 includes mounting cylindrical portions 30 and 40. The helical bellows cylindrical portion 20 and the mounting cylindrical portions 30 and 40 are in communication with each other. The mounting cylindrical portion 30 is located on one side (X1 side) of the helical bellows cylindrical portion 20 along the X direction, and the mounting cylindrical portion 40 is located on the other side (X2 side). In the cylindrical portion 12, the mounting cylindrical portion 30, the helical bellows cylindrical portion 20, and the mounting cylindrical portion 40 are arranged in that order from one side (X1 side) along the axial direction. One or both of the two mounting cylindrical portions 30 and 40 may be omitted.
[0028] The mounting cylinder portions 30 and 40 are parts that are attached to the vehicle body panel. For example, one of the mounting cylinder portions 30 and 40 is attached to the vehicle body panel, and the other is attached to the door panel. A fitting groove 32 is formed on the outer surface 13 of the mounting cylinder portion 30. A fitting groove 42 is formed on the outer surface 13 of the mounting cylinder portion 40. The peripheral edges of the holes in the vehicle body panel fit into the fitting grooves 32 and 42. The mounting cylinder portions 30 and 40 protect the portion of the wire harness 82 that penetrates the hole in the vehicle body panel from the peripheral edges of the hole. The spiral bellows cylinder portion 20 protects the portion of the wire harness 82 that extends out of the hole in the vehicle body panel. In this embodiment, the axial direction of the cylinder portion 12 follows a single straight line from one end to the other. The cylinder portion 12 is formed in a straight line. The cylinder portion 12 may be bent when mounted on the vehicle.
[0029] In the axial direction of the cylindrical portion 12, the lengths of the helical bellows portion 20 and the mounting cylindrical portions 30 and 40 are not particularly limited and can be set as appropriate. For example, in the axial direction of the cylindrical portion 12, the helical bellows portion 20 may be longer than the mounting cylindrical portions 30 and 40. For example, in the axial direction of the cylindrical portion 12, the helical bellows portion 20 may occupy more than half of the length of the cylindrical portion 12.
[0030] The helical bellows section 20 has an end section and an intermediate section that are aligned along the axial direction. The shapes of the peaks 21 and valleys 22 are slightly different in the end section and the intermediate section. Specifically, the peaks 21 and valleys 22 of the end section spread outward along the axial direction of the cylindrical section 12 more than the peaks 21 and valleys 22 of the intermediate section. The direction of extension of the peaks 21 and valleys 22 of the end section is closer to parallel to the axial direction of the cylindrical section 12 than the direction of extension of the peaks 21 and valleys 22 of the intermediate section. However, the shapes of the peaks 21 and valleys 22 may be the same in the end section and the intermediate section of the helical bellows section 20.
[0031] The wiring fixing portion 50 is provided at one end of the cylindrical portion 12. The wiring fixing portion 50 includes a plurality (in this case, a pair) of extension pieces 52. The plurality of extension pieces 52 are spaced apart from each other along the circumferential direction of the cylindrical portion 12. The plurality of extension pieces 52 protrude axially from the tip of the mounting cylindrical portion 30. Multiple slits are formed at multiple locations along the circumferential direction of the cylindrical portion, forming the plurality of extension pieces 52.
[0032] For example, with the wire harness 82 passed through the grommet 10, a fastening member such as adhesive tape or a cable tie is wrapped around the wire harness 82 and the pair of extension pieces 52, thereby fixing the wire harness 82 to one end of the grommet 10.
[0033] As shown in Figure 2, the inner diameter of the mounting cylinder portion 40 is the same as or larger than the inner diameter of the helical bellows cylinder portion 20. It is preferable that the inner diameter of the portion of the mounting cylinder portion 40 in which the fitting groove 42 is formed is the same as or larger than the inner diameter of the helical bellows cylinder portion 20.
[0034] The spacing between the multiple extension pieces 52 is smaller than the inner diameter of the mounting cylinder portion 30. The multiple extension pieces 52 are spaced apart from each other in the circumferential direction and are not cylindrical, so they are more easily expanded in diameter than the mounting cylinder portion 30.
[0035] As shown in Figure 2, the inner diameter of the portion of the mounting cylinder 30 in which the fitting groove 32 is formed is preferably the same as or larger than the inner diameter of the helical bellows cylinder 20. The inner diameter of the tip of the mounting cylinder 30 on the extension piece 52 side is smaller than the inner diameter of the helical bellows cylinder 20. This portion is near the slit forming the extension piece 52 and is thinner than the portion of the mounting cylinder 30 in which the fitting groove 32 is formed, making it easier to expand in diameter than the portion of the mounting cylinder 30 in which the fitting groove 32 is formed.
[0036] The grommet 10 is formed by a mold M having a plurality of outer molds OM and at least one inner mold IM. A fluid resin is filled between the outer molds OM and the inner mold IM. The outer molds OM form the shape of the outer surface 13 of the grommet 10. The inner mold IM forms the shape of the inner surface 14 of the grommet 10. In this embodiment, four outer molds OM and one inner mold IM are provided as outer molds OM and inner mold IM for forming the helical bellows cylinder portion 20. The four outer molds OM are arranged in the circumferential direction of the helical bellows cylinder portion 20. Hereinafter, when it is necessary to distinguish between the four outer molds OM, they will be referred to as outer molds OM1, OM2, OM3, and OM4. The number of outer molds OM and inner molds IM for the mounting cylinder portions 30 and 40 may be the same as or different from the number of outer molds OM and inner molds IM for the helical bellows cylinder portion 20.
[0037] In Figures 4 to 6, arrows RD indicate the demolding direction (removal direction) of each outer mold OM. Arrow RD1 indicates the demolding direction of outer mold OM1. Arrow RD2 indicates the demolding direction of outer mold OM2. Arrow RD3 indicates the demolding direction of outer mold OM3. Arrow RD4 indicates the demolding direction of outer mold OM4. The angle between the demolding directions RD of adjacent outer molds OM may be equal to the value obtained by dividing 360 degrees by the number of outer molds OM. For example, in the case of four outer molds OM, the angle between the demolding directions RD of adjacent outer molds OM may be 90 degrees, which is 360 degrees divided by 4.
[0038] Multiple outer molds OM may form equal areas of the helical bellows cylinder portion 20 in the circumferential direction. For example, four outer molds OM may each form 90 degrees of the outer surface 13 of the helical bellows cylinder portion 20.
[0039] Multiple dividing lines PL are formed on the outer surface 13 of the helical bellows cylinder portion 20. The dividing lines PL are traces left by the removal of multiple outer molds OM. The dividing lines PL are formed at the boundary portions of the molded surfaces of adjacent outer molds OM. The dividing lines PL extend along the axial direction of the cylinder portion 12. For example, the dividing lines PL are portions on the outer surface 13 that are slightly convex toward the outer surface 13 side in the circumferential direction compared to the portions on either side of the dividing line PL. The dividing lines PL are similar to those that can occur in general injection molding. Basically, the number of dividing lines PL in the circumferential direction of the helical bellows cylinder portion 20 is the same as the number of outer molds OM arranged in the circumferential direction of the helical bellows cylinder portion 20. In this embodiment, since there are four outer molds OM for the helical bellows cylinder portion 20, four dividing lines PL are provided on the helical bellows cylinder portion 20. If distinction is necessary between the four dividing lines PL, they shall be designated as dividing lines PL1, PL2, PL3, and PL4. Dividing line PL1 is formed at the boundary between outer mold OM1 and outer mold OM2. Dividing line PL2 is formed at the boundary between outer mold OM2 and outer mold OM3. Dividing line PL3 is formed at the boundary between outer mold OM3 and outer mold OM4. Dividing line PL4 is formed at the boundary between outer mold OM4 and outer mold OM1.
[0040] The portion of the spiral bellows cylinder 20 between adjacent dividing lines PL is called a divided portion P. The number of divided portions P is the same as the number of dividing lines PL. In this embodiment, since there are four dividing lines PL, four divided portions P are provided. When it is necessary to distinguish between the four divided portions P, they are referred to as divided portions P1, P2, P3, and P4. Divided portion P1 is the portion between dividing line PL1 and dividing line PL2. Divided portion P2 is the portion between dividing line PL2 and dividing line PL3. Divided portion P3 is the portion between dividing line PL3 and dividing line PL4. Divided portion P4 is the portion between dividing line PL4 and dividing line PL1. Divided portion P1 is the portion formed by the outer mold OM1. Divided portion P2 is the portion formed by the outer mold OM2. Divided portion P3 is the portion formed by the outer mold OM3. Divided portion P4 is the portion formed by the outer mold OM4.
[0041] Here, we focus on the dividing lines PL1 and PL2, and the divided portion P1 between them. Dividing lines PL1 and PL2 are examples of first and second dividing lines that are adjacent to each other along the circumferential direction of the helical bellows cylinder portion 20. Divided portion P1 is an example of a first portion located between the first and second dividing lines. Hereinafter, dividing line PL1 may be referred to as the first dividing line PL1, dividing line PL2 as the second dividing line PL2, and divided portion P1 as the first portion P1.
[0042] In a cross-section perpendicular to the axial direction, the direction connecting the first dividing line PL1 and the second dividing line PL2 is defined as the first direction D1. In the same cross-section, the direction perpendicular to the first direction D1 is defined as the second direction RD1. The second direction RD1 is the demolding direction of the outer mold OM1 in the first part P1 of the multiple outer molds OM. In Figure 4, the direction indicated by arrow D1 is the first direction D1. In Figure 4, the direction indicated by arrow RD1 is the second direction RD1. Here, the first direction D1 is the direction along the Y direction. The second direction RD1 is the direction along the Z1 direction.
[0043] In the helical bellows section 20, the peaks 21 and valleys 22 extend in a helical shape, so the shape of the outer surface 13 at each position of the first dividing line PL1 and the second dividing line PL2 also transitions along the axial direction (X direction). For example, at the position of the cross section in Figure 4, the valleys 22 are located at each position of the first dividing line PL1 and the second dividing line PL2. At the position of the cross section in Figure 5, the portion between the peaks 21 and the valleys 22 is located at each position of the first dividing line PL1 and the second dividing line PL2. At the position of the cross section in Figure 6, the peaks 21 are located at each position of the first dividing line PL1 and the second dividing line PL2.
[0044] In FIG. 4 where the valley portions 22 are located at the first parting line PL1 and the second parting line PL2, the first portion P1 includes three peak portions 21A, 21B, 21C and four valley portions 22A, 22B, 22C, 22D. In FIG. 5 and FIG. 6, the positions of the peak portions 21 and the valley portions 22 are shifted in the circumferential direction from the state of FIG. 4. In FIG. 5, the first portion P1 includes three peak portions 21A, 21B, 21C and three valley portions 22B, 22C, 22D. In FIG. 5, the valley portion 22A is included in the adjacent divided portion P4. In FIG. 6, the first portion P1 includes four peak portions 21A, 21B, 21C, 21D and three valley portions 22B, 22C, 22D. The peak portion 21D is included in the adjacent divided portion P2 in FIG. 5, and is included in the first portion P1 in FIG. 6.
[0045] The first portion P1 has an outer surface portion 24 and an inner surface portion 26. The outer surface portion 24 is a portion extending from the parting line PL. The inner surface portion 26 is a portion of the inner surface 14 located on the side opposite to the outer surface portion 24.
[0046] Here, the first portion P1 has outer surface portions 24L, 24R and inner surface portions 26L, 26R. The outer surface portion 24L is a portion extending from the first parting line PL1. The outer surface portion 24R is a portion extending from the second parting line PL2. The outer surface portion 24L is a portion from the first parting line PL1 to the peak portion 21 or the valley portion 22 closest to the first parting line PL1 in the first portion P1. The outer surface portion 24R is a portion from the second parting line PL2 to the peak portion 21 or the valley portion 22 closest to the second parting line PL2 in the first portion P1. The inner surface portion 26L is a portion of the inner surface 14 located on the side opposite to the outer surface portion 24L. The inner surface portion 26R is a portion of the inner surface 14 located on the side opposite to the outer surface portion 24R.
[0047] In the spiral bellows tube portion 20, since the crest portions 21 and the trough portions 22 extend in a spiral shape, the shapes of the outer surface portions 24L, 24R and the shapes of the inner surface portions 26L, 26R also transition along the axial direction (X direction). In FIG. 4, the first portion P1 has outer surface portions 24L1, 24R1 and inner surface portions 26L1, 26R1. In FIG. 5, the first portion P1 has outer surface portions 24L2, 24R2 and inner surface portions 26L2, 26R2. In FIG. 6, the first portion P1 has outer surface portions 24L3, 24R3 and inner surface portions 26L3, 26R3. In the axial direction, the shapes of the outer surface portions 24L, 24R and the shapes of the inner surface portions 26L, 26R are the same at a first position and a second position where the crest portion 21 is offset by one in the circumferential direction.
[0048] The outer surface portion 24L1 in FIG. 4 is a surface extending from the trough portion 22A of the first parting line PL1 toward the adjacent crest portion 21A. The outer surface portion 24R1 in FIG. 4 is a surface extending from the trough portion 22D of the second parting line PL2 toward the adjacent crest portion 21C. The inner surface portion 26L1 in FIG. 4 is the surface on the opposite side of the outer surface portion 24L1. The inner surface portion 26R1 in FIG. 4 is the surface on the opposite side of the outer surface portion 24R1.
[0049] The outer surface portion 24L2 in FIG. 5 is a surface extending from a position between the crest portion 21A and the trough portion 22A on the first parting line PL1 toward the adjacent crest portion 21A. The outer surface portion 24R2 in FIG. 5 is a surface extending from a position between the crest portion 21D and the trough portion 22D on the second parting line PL2 toward the adjacent trough portion 22D. The inner surface portion 26L2 in FIG. 5 is the surface on the opposite side of the outer surface portion 24L2. The inner surface portion 26R2 in FIG. 5 is the surface on the opposite side of the outer surface portion 24R2.
[0050] The outer surface portion 24L3 in FIG. 6 is a surface extending from the crest portion 21A of the first parting line PL1 toward the adjacent trough portion 22B. The outer surface portion 24R3 in FIG. 6 is a surface extending from the crest portion 21D on the second parting line PL2 toward the adjacent trough portion 22D. The inner surface portion 26L3 in FIG. 6 is the surface on the opposite side of the outer surface portion 24L3. The inner surface portion 26R3 in FIG. 6 is the surface on the opposite side of the outer surface portion 24R3.
[0051] In this embodiment, the first portion P1 has an undercut shape at some positions along the axial direction and does not have an undercut shape at other positions. In Figure 4, where the valley portion 22 is located on the first dividing line PL1 and the second dividing line PL2, and in Figure 6, where the peak portion 21 is located on the first dividing line PL1 and the second dividing line PL2, the first portion P1 does not have an undercut shape. In Figure 5, where the portion between the peak portion 21 and the valley portion 22 is located on the first dividing line PL1 and the second dividing line PL2, the first portion P1 has an undercut shape. The undercut shape is the portion of the outer surfaces 24L and 24R that extends outward from the dividing line PL along the first direction D1. In Figure 5, one outer surface portion 24L2 has an undercut shape. In Figure 5, the other outer surface portion 24R2 does not have an undercut shape. Undercut shapes tend to occur in the outer surface portion 24 that extends from the location of the valley portion 22 or from a location between the peak portion 21 and the valley portion 22 toward the adjacent peak portion 21.
[0052] In portions without an undercut shape, no interference occurs between the outer mold OM and the inner mold IM when removing the outer mold OM. In portions with an undercut shape, interference may occur between the outer mold OM and the inner mold IM when removing the outer mold OM. In this disclosure, the helical bellows cylinder portion 20 is configured so that even in portions with an undercut shape, no interference occurs between the outer mold OM and the inner mold IM when removing the outer mold OM.
[0053] In the portion having an undercut shape, the innermost part of the outer surface 24 along the first direction D1 is defined as the innermost portion 25. Also, in the portion having an undercut shape, the outermost part of the inner surface 26 along the first direction D1 is defined as the outermost portion 27. In Figure 7, the position of the first dividing line PL1 on the outer surface 24L2 is the innermost portion 25. The position of the end on the mountain portion 21A side of the inner surface 26L2 is the outermost portion 27. In the portion having an undercut shape, the innermost portion 25 is located further outward (in this case, towards Y2) along the first direction D1 than the outermost portion 27. As a result, even in the portion having an undercut shape, no interference occurs between the outer mold OM and the inner mold IM when the outer mold OM is removed.
[0054] At a position having an undercut shape, the distance between the innermost portion 25 and the outermost portion 27 in the first direction D1 may be, for example, 30% or more of the thickness of the helical bellows cylinder portion 20. In Figure 7, dimension D2 indicates the distance between the innermost portion 25 and the outermost portion 27 in the first direction D1. In Figure 7, dimension D3 indicates the thickness of the helical bellows cylinder portion 20. The thickness of the helical bellows cylinder portion 20 may be, for example, a dimension along the first direction D1 at the position of the innermost portion 25. Dimension D2 is 30% or more of dimension D3. Dimension D2 may be 50% or more of dimension D3. Dimension D2 may be 70% or more of dimension D3. Dimension D2 may be 80% or more of dimension D3. Dimension D2 may be 90% or more of dimension D3. Dimension D2 may be 100% or less of dimension D3.
[0055] When the outer mold OM1 is removed (released) in the second direction RD1, the portion having an undercut shape (the portion between the outer surface portion 24L2 and the inner surface portion 26L2) may be compressed. Even in this case, the fact that dimension D2 is 30% or more of dimension D3 can prevent the degree of compression from becoming too large.
[0056] In both the axial and circumferential directions, it is preferable that the distance between the two outer surfaces 24 gradually narrows from the valleys 22 on both sides of a single peak 21 toward the peak 21. It is preferable that the valleys 22 on both sides of a single peak 21 do not form a C-shape toward the peak 21. If the valleys 22 on both sides of a single peak 21 form a C-shape toward the peak 21, a portion will be created where the distance between the two outer surfaces 24 widens toward the peak 21. In this way, the portion where the distance between the two outer surfaces 24 widens toward the peak 21 tends to form an undercut shape.
[0057] In Figure 7, angle AG1 is the angle of the outer surface portion 24 from the dividing line PL toward the peak portion 21A. When angle AG1 exceeds 90 degrees, an undercut shape is formed. In this case, typically, the end of the outer surface portion 24 on the dividing line PL side becomes the innermost portion 25, and the end of the inner surface portion on the peak portion 21A side becomes the outermost portion 27. In the example shown in Figure 7, angle AG1 exceeds 90 degrees, resulting in an undercut shape. In the example shown in Figure 7, angle AG1 is 95 degrees. When an undercut shape is present, the closer angle AG1 is to 90 degrees, the smaller dimension D2 can be. For example, angle AG1 may be 120 degrees or less, 110 degrees or less, or 100 degrees or less.
[0058] The number of peaks 21 along the circumferential direction may be the same as the number of dividing lines PL. In this case, an outer mold OM is provided for each peak 21. The number of peaks 21 along the circumferential direction may be greater than the number of dividing lines PL. In this case, the number of outer molds OM can be less than the number of peaks 21. The number of peaks 21 along the circumferential direction of the helical bellows cylinder portion 20 may be twice or more the number of dividing lines PL. In this case, one outer mold OM contains two or more peaks 21. Here, the number of peaks 21 along the circumferential direction is 12, and the number of dividing lines PL is 4, so the number of peaks 21 along the circumferential direction is three times the number of dividing lines PL. The number of peaks 21 along the circumferential direction may be more than one and less than or equal to two times the number of dividing lines PL. The number of peaks 21 along the circumferential direction may be two times or more and less than or equal to three times the number of dividing lines PL. The number of peaks 21 along the circumferential direction may be three times or more the number of dividing lines PL.
[0059] The number of peaks 21 along the circumferential direction of the helical bellows cylinder portion 20 may be an integer multiple of the number of dividing lines PL. In this case, the shape of the molding surface forming the outer surface 13 of the helical bellows cylinder portion 20 can be made the same in multiple outer molds OM. Here, the number of peaks 21 along the circumferential direction is 12, and the number of dividing lines PL is 4, so the number of peaks 21 along the circumferential direction of the helical bellows cylinder portion 20 is 3 times the number of dividing lines PL. The number of peaks 21 along the circumferential direction of the helical bellows cylinder portion 20 may be 2 times the number of dividing lines PL, or 4 times or more. The number of peaks 21 along the circumferential direction of the helical bellows cylinder portion 20 does not have to be an integer multiple of the number of dividing lines PL.
[0060] <Wire harness with grommet> The wire harness with grommet 80 comprises the grommet 10 and a wire harness 82 passed through the grommet 10.
[0061] The wire harness 82 includes a wiring member and at least one connector provided at the end of the wiring member. The wiring member is, for example, an electric wire that transmits electricity or an optical cable that transmits light. Typically, multiple transmission members are bundled together to form the wiring member. The wiring member passes through the grommet 10. The grommet 10 is fitted to the middle portion of the wiring member. Hereinafter, the portion of the wiring member to which the grommet 10 is fitted will be referred to as the grommet fitting portion. At least one connector is provided at the end of the wiring member that is one end away from the grommet fitting portion.
[0062] For example, the wire harness 82 is passed through the grommet 10 from one end beyond the grommet mounting portion. In this case, the connector on one end of the wire harness 82 beyond the grommet mounting portion needs to pass through the grommet 10 from one end to the other. If the inner diameter of the cylindrical portion 12 is smaller than the outer diameter of the connector, the grommet 10 needs to be expanded and deformed.
[0063] If the wire harness 82 has multiple connectors on one end of the grommet mounting portion, the outer dimensions of the connectors and the inner diameter of the grommet 10 are set so that the largest connector can pass through the grommet 10. In this case, the connectors other than the largest one can also pass through the grommet 10. Note that the other end of the wire harness 82 that is not mounted on the grommet 10 does not pass through the grommet 10, so the size of the connector does not need to be considered.
[0064] Here, the inner diameter of the portion of the mounting cylinder 30, 40 in which the fitting grooves 32, 42 are formed may be larger than the outer dimensions of the largest connector. The outer dimensions of the connector are the largest dimensions in the cross-section of the connector. For example, if the connector is rectangular, it is the dimension connecting two opposite corners of the square as viewed from the axial direction. In this way, if the inner diameter of the portion of the mounting cylinder 30, 40 in which the fitting grooves 32, 42 are formed is larger than the outer dimensions of the largest connector, the portion of the mounting cylinder 30, 40 in which the fitting grooves 32, 42 are formed will not undergo expansion deformation when the connector is inserted.
[0065] The outer dimensions of the connector may be larger than the inner diameter of the helical bellows section 20. In this case, the helical bellows section 20 expands in diameter when the connector is passed through it. For example, the helical bellows section 20 expands in diameter when its tip is twisted in the direction of arrow A1 in Figure 1.
[0066] The wire harness 82 may be inserted into the grommet 10 when the grommet 10 is not attached to the vehicle body, or when the grommet 10 is attached to the vehicle body. In the latter case, the wire harness 82 is inserted into the grommet 10 with the periphery of the hole in the vehicle body panel fitted into the fitting groove 32 or fitting groove 42. In this case, the portion of the mounting cylinder 30, 40 in which the fitting grooves 32, 42 are formed becomes difficult to expand in diameter because the periphery of the hole in the vehicle body panel is fitted into the fitting grooves 32, 42. Even in this case, the inner diameter of the portion of the mounting cylinder 30, 40 in which the fitting grooves 32, 42 are formed is larger than the outer diameter of the largest connector among the connectors that pass through the grommet 10, so the wire harness 82 can be passed through the portion of the mounting cylinder 30, 40 in which the fitting grooves 32, 42 are formed without significantly expanding in diameter.
[0067] The thickness of the wiring member is usually smaller than the outer dimensions of the connector. Therefore, if the grommet 10 is large enough to allow the connector to pass through, the wiring member can also be passed through it. The wiring member may be branched. In this case, it may be necessary to pass some of the branch wires of the wiring member and some of the connectors through the grommet 10 at the same time. In this case, for example, the inner diameter of the portion of the mounting cylinder 30, 40 in which the fitting grooves 32, 42 are formed may be greater than or equal to the sum of the thickness of the branch wires of the wiring member being passed through at the same time and the dimension of the short side of the connector. This makes it possible to pass some of the branch wires of the wiring member and some of the connectors through the grommet 10 at the same time without expanding or deforming the portion of the mounting cylinder 30, 40 in which the fitting grooves 32, 42 are formed.
[0068] The diameter of the grommet mounting portion of the wiring member may be smaller than the inner diameter of the helical bellows portion 20. In this case, the grommet-equipped wire harness 80 may be held in a reduced-diameter deformed state. For example, the helical bellows portion 20 is reduced in diameter by twisting its tip in the direction of arrow A2 in Figure 1. For example, the helical bellows portion 20 may be held in a reduced-diameter deformed state by fixing the wiring fixing portion 50 to the wire harness 82 while the helical bellows portion 20 is in a reduced-diameter deformed state. The inner surface 14 of the helical bellows portion 20 (the inner surface 14 of the valley portion 22) may be in close contact with the grommet mounting portion.
[0069] [Embodiment 2] A grommet according to Embodiment 2 will be described. Figure 8 is a cross-sectional view showing a grommet 110 according to Embodiment 2. Figure 9 is a cross-sectional view showing the process of forming the helical bellows portion 120 of the grommet 110. Figure 9 corresponds to a cross-section at the same position as in Figure 5. In the following description, components similar to those described so far will be denoted by the same reference numerals and their descriptions will be omitted.
[0070] In the grommet 110, the shape of the helical bellows portion 120 differs from the shape of the helical bellows portion 20 in the grommet 10. The first portion P1 of the helical bellows portion 120 does not have an undercut shape at any position along the axial direction.
[0071] The number of peaks 21 and dividing lines PL in the grommet 110 is the same as the number of peaks 21 and dividing lines PL in the grommet 10. In the grommet 110, the depth from the peaks 21 to the valleys 22 is shallower than the depth from the peaks 21 to the valleys 22 in the grommet 10. As a result, in the outer surface portion 24L2, the angle AG1 from the position of the dividing line PL toward the peaks 21 can be made smaller than 90 degrees, and an undercut shape can be avoided.
[0072] <Reference Example> Figure 10 is a cross-sectional view showing the process of forming the helical bellows portion S11 of the grommet S10 according to Reference Example 1.
[0073] The number of peaks S12, valleys S13, and dividing lines S14 in grommet S10 is the same as the number of peaks 21, valleys 22, and dividing lines PL in grommet 10. In grommet S10, the depth from peaks S12 to valleys S13 is deeper than the depth from peaks 21 to valleys 22 in grommet 10. In grommet S10, the greater depth from peaks S12 to valleys S13 gives grommet S10 an undercut shape, and furthermore, the innermost part S15 of the outer surface is located inward along the first direction compared to the outermost part S16 of the inner surface. In this case, interference with the inner mold S18 may occur when removing the outer mold S17.
[0074] As can be seen from the three grommets 10, 110, and S10, when the number of peaks 21 and S12 and the number of dividing lines PL and S14 are the same, the shallower the depth from the peaks 21 and S12 to the valleys 22 and S13, the less likely an undercut shape is to occur. As a result, grommets 10 and 110 are easier to manufacture than grommet S10. On the other hand, in terms of diameter change function or ease of diameter change, a deeper depth from the peaks 21 and S12 to the valleys 22 and S13 is preferable.
[0075] Figure 11 is a cross-sectional view showing the process of forming the helical bellows portion S21 of the grommet S20 according to Reference Example 2.
[0076] The number of dividing lines S24 in grommet S20 is different from the number of dividing lines PL in grommet 110. There are two dividing lines S24 in grommet S20. Except for the number of dividing lines S24, grommet S20 has the same configuration as grommet 110. Therefore, the number of peaks S22 and valleys S23 in grommet S20 is the same as the number of peaks 21 and valleys 22 in grommet 110. In grommet S20, the depth from peak S22 to valley S23 is the same as the depth from peak 21 to valley 22 in grommet 110.
[0077] The helical bellows portion S21 of the grommet S20, which has two dividing lines S24, is formed by two outer molds S27. When there are two dividing lines S24, an undercut shape occurs at one of the positions along the axial direction. For example, as shown in Figure 11, an undercut shape occurs in the cross section where the dividing line S24 is located at the valley S23.
[0078] As can be seen from the two grommets 110 and S20, when the configuration is the same except for the number of dividing lines PL and S24, the more dividing lines PL and S24 there are, the less likely undercut shapes are to occur. As a result, grommet 110 is easier to manufacture than grommet S20. When forming the helical bellows cylinder portion 20, it is preferable that the number of dividing lines PL be three or more in order to prevent undercut shapes from occurring.
[0079] If there are two dividing lines S24, it is preferable that in the portion having an undercut shape, the innermost portion S25 is positioned outward in the first direction (Y direction) compared to the outermost portion S26, as in the grommet 10 described above.
[0080] In the example shown in Figure 11, the innermost portion S25 is not configured to be located outward along the first direction (Y direction) compared to the outermost portion S26. In this case, interference with the inner mold S28 may occur when removing the outer mold S27. In the example shown in Figure 11, for example, by making the depth from the peak portion S22 to the valley portion S23 shallower than the depth shown in Figure 11, the innermost portion S25 can be configured to be located outward along the first direction (Y direction) compared to the outermost portion S26.
[0081] <Effects, etc.> With the grommet 10 and wire harness 80 configured as described above, the first portion P1 has an undercut shape. Even in this case, the innermost portion 25 in the portion with the undercut shape is located outward along the first direction D1 from the outermost portion 27. Furthermore, with the grommet 110, the first portion P1 does not have an undercut shape at any position along the axial direction. As a result, contact between the outer mold OM and the inner mold IM can be suppressed when removing the mold M.
[0082] Furthermore, with respect to the grommet 10 and the wire harness 80 with the grommet, the first portion P1 has an undercut shape at least in some positions along the axial direction, and at the positions with the undercut shape, the distance between the innermost portion 25 and the outermost portion 27 in the first direction D1 is 30% or more of the thickness of the helical bellows cylinder portion 20. Because the outer surface 13 of the first portion P1 has an undercut shape, the first outer mold OM and the grommet 10 interfere with each other when the outer mold OM is removed. Even in this case, the outer mold OM can be removed by the elasticity of the grommet 10. The distance between the innermost portion 25 and the outermost portion 27 in the first direction D1 is 30% or more of the thickness of the helical bellows cylinder portion 20, which prevents the distance between the outer mold OM and the inner mold IM from becoming too small when the outer mold OM is removed.
[0083] Furthermore, the grommet 110 has three or more dividing lines PL, and the first portion P1 does not have an undercut shape at any position along the axial direction. This makes it possible to suppress interference between the first outer mold OM and the grommet 110 when the outer mold OM is removed.
[0084] Furthermore, with grommets 10, 110 and wire harness 80 with grommets, the number of peaks 21 along the circumferential direction of the helical bellows cylinder portion 20 is more than twice the number of dividing lines PL. As a result, the number of peaks 21 included in one outer mold OM increases, and the number of outer molds OM can be reduced.
[0085] Furthermore, the number of peaks 21 along the circumferential direction of the helical bellows section 20 is an integer multiple of the number of dividing lines PL. This makes it possible to make the shape of the portion forming the helical bellows section 20 among the multiple outer molds OM identical.
[0086] [Note] The components described in each of the above embodiments and modifications can be combined as appropriate, as long as they do not contradict each other.
[0087] 10, 110 Grommet 12 Cylinder section 13 Outer surface 14 Inner surface 20 Helical bellows section 21, 21A, 21B, 21C, 21D Peak section 22, 22A, 22B, 22C, 22D Valley section 24, 24L1, 24L2, 24L3, 24R1, 24R2, 24R3 Outer surface section 25 Innermost section 26, 26L1, 26L2, 26L3, 26R1, 26R2, 26R3 Inner surface section 27 Outermost section 30, 40 Mounting cylinder section 32, 42 Fitting groove 50 Wiring fixing section 52 Extension piece 80 Wire harness with grommet 82 Wire harness D1 First direction M Mold IM Inner mold OM, OM1, OM2, OM3, OM4 Outer mold P, P2, P3, P4 Divided part P1 Divided part (first part) PL, PL3, PL4 Dividing line PL1 Dividing line (first dividing line) PL2 Dividing line (second dividing line) RD, RD2, RD3, RD4 Release direction RD1 Release direction (second direction) S10, S20 Grommet of the example S11, S21 Helical bellows section of the example S12, S22 Peak section of the example S13, S23 Valley section of the example S14, S24 Dividing line of the example S15, S25 Innermost part of the example S16, S26 Outermost part of the example S17, S27 Outer mold of the example S18, S28 Reference example internal mold
Claims
1. A grommet formed by a mold having a plurality of outer molds and at least one inner mold, comprising a cylindrical portion including a helical bellows portion, the helical bellows portion having peaks and valleys extending helically around the axis of the cylindrical portion, a plurality of dividing lines formed on the outer surface of the helical bellows portion along the axial direction of the cylindrical portion as traces of the plurality of outer molds being removed, the plurality of dividing lines having a first dividing line and a second dividing line adjacent to the first dividing line along the circumferential direction of the helical bellows portion, the helical bellows portion having a first portion located between the first dividing line and the second dividing line in the circumferential direction, in a cross section perpendicular to the axial direction, the direction connecting the first dividing line and the second dividing line is defined as the first direction, and the direction perpendicular to the first direction is defined as the second direction, the first portion having an outer surface portion extending from each of the first dividing line and the second dividing line, and an inner surface portion opposite to the outer surface portion. A grommet wherein the innermost portion of the outer surface along the first direction is defined as the innermost portion, the outermost portion of the inner surface along the first direction is defined as the outermost portion, and in the first portion, at any position along the axial direction, the innermost portion does not have an undercut shape, or if it does, in the portion having an undercut shape, the innermost portion is located further outward along the first direction than the outermost portion.
2. A grommet according to claim 1, wherein the plurality of dividing lines have three or more dividing lines, and the first portion does not have an undercut shape at any position along the axial direction.
3. A grommet according to claim 1, wherein the first portion has an undercut shape at at least a portion of the position along the axial direction, and the distance between the innermost portion and the outermost portion in the first direction at the position having the undercut shape is 30% or more of the thickness of the helical bellows portion.
4. A grommet according to any one of claims 1 to 3, wherein the number of peaks along the circumferential direction of the helical bellows tube is at least twice the number of the plurality of dividing lines.
5. A grommet according to claim 4, wherein the number of peaks along the circumferential direction of the helical bellows tube is an integer multiple of the number of dividing lines.
6. A wire harness with a grommet, comprising: a grommet according to any one of claims 1 to 3; and a wire harness passed through the cylindrical portion of the grommet.