Grommet and rotary electric machine

Abstract

To prevent damage due to excessive compression of a grommet having a linear projection.SOLUTION: The grommet 6 includes the contact portion 21 that comes into contact with the 4N of the cutout portion provided in the opening portion of the case 4, the pressing portion 22 that is pressed by the cover 5 that closes the opening portion, the through hole 23 into which the wire is inserted, the groove portion side 21G provided in the contact portion 21 along the direction intersecting the penetrating direction of the through hole 23, and the line-shaped protruding portion 24 provided on the groove portion side 21G along the direction intersecting the penetrating direction. When the cover 5 is attached to the opening part, the projection part 24 is pressed against the cutout part 4N and compressed, and a gap 21G is left around the projection part 24 in the groove part 24V.SELECTED DRAWING: Figure 13

Description

[Technical Field]

[0001] The present invention relates to a grommet and a rotating electric machine. [Background technology]

[0002] Devices equipped with a motor as a drive source require electric wires to supply power to the coil housed in the motor case. The electric wires are often routed through a notch in the case, and a sealant is provided to close the gap between the notch and the electric wire to prevent the intrusion of foreign matter (water, dust, etc.) and to protect the electric wires. Known examples of such sealants include grommets (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-214429 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-369346 Summary of the Invention [Problem to be solved by the invention]

[0004] The grommets disclosed in Patent Documents 1 and 2 have linear protrusions (lips, ribs) on their outer periphery. When the grommet is attached to a case, the linear protrusions are compressed, improving sealing performance. However, if the linear protrusions are compressed excessively, the grommet may be damaged.

[0005] SUMMARY OF THE INVENTION In consideration of the above circumstances, an object of the present invention is to prevent damage to a grommet having a linear protrusion due to excessive compression. [Means for solving the problem]

[0006] In order to solve the above problem, the grommet of the present invention comprises a contact portion that contacts a notch provided in an opening of a case, a pressing portion that is pressed by a cover that covers the opening, a through hole into which an electric wire is inserted, a groove portion provided in the contact portion along a direction intersecting the penetration direction of the through hole, and a linear protrusion portion provided in the groove portion along a direction intersecting the penetration direction, and when the cover is attached to the opening, the protrusion portion is pressed against the notch and compressed, leaving a gap around the protrusion within the groove portion.

[0007] The protrusions may be provided at a plurality of locations in the through-hole direction, and small diameter portions having small inner diameters may be provided in the through-hole at positions corresponding to one or more of the protrusions.

[0008] The protrusions may be provided at three or more locations in the penetration direction, and the small diameter portions may be provided at positions corresponding to two of the plurality of protrusions that are not adjacent to each other.

[0009] The grommet may include a flange portion facing at least one of the outer surface and the inner surface of the case around the notch.

[0010] A rotating electric machine according to the present invention includes any one of the above-described grommets, the cover, and the case.

[0011] The notch and the contact portion may be tapered. [Effects of the Invention]

[0012] According to the present invention, it is possible to prevent damage to a grommet having a linear protrusion due to excessive compression. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a perspective view showing a motor according to an embodiment of the present invention; [Figure 2] 1 is an exploded view showing a motor according to an embodiment of the present invention. [Figure 3] 1 is a perspective view showing a grommet according to an embodiment of the present invention. [Figure 4] 1 is a front view showing a grommet according to an embodiment of the present invention. [Figure 5] FIG. 1 is a left side view showing a grommet according to an embodiment of the present invention. [Figure 6] FIG. 5 is a cross-sectional view showing a cross section II of FIG. 4. [Figure 7] FIG. 2 is a bottom view showing the grommet according to the embodiment of the present invention. [Figure 8] FIG. 5 is a cross-sectional view showing the II-II cross section of FIG. [Figure 9] FIG. 3 is a cross-sectional view showing a protrusion according to one embodiment of the present invention. [Figure 10] 10A and 10B are schematic diagrams illustrating a state in which a grommet according to an embodiment of the present invention is attached to a notch portion. [Figure 11] 1 is a schematic diagram showing a state in which a grommet according to an embodiment of the present invention is attached to a cutout portion. FIG. [Figure 12] 10 is a cross-sectional view showing a state in which the grommet according to the embodiment of the present invention comes into contact with the notch and the cover. FIG. [Figure 13] 10 is a cross-sectional view showing a state in which a protrusion of a grommet is compressed after assembly is completed according to an embodiment of the present invention. FIG. [Figure 14] FIG. 10 is a cross-sectional view showing a state in which a convex portion of a conventional grommet is compressed. [Figure 15] FIG. 1 is a schematic diagram showing a conventional grommet. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a grommet 6 and a rotating electric machine according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a motor 1 is shown as an example of a rotating electric machine, but the present invention may also be applied to a generator.

[0015] First, the overall configuration of motor 1 will be described. Fig. 1 is a perspective view of motor 1. Fig. 2 is an exploded view of motor 1. For ease of explanation, the axial direction of rotating shaft 10 (see Fig. 2) of motor 1 will be described as the up-down direction, and the side on which grommet 6 is exposed will be described as the front side, but motor 1 may be installed in any orientation. In each figure, U, Lo, Fr, Rr, L, and R represent up, down, front, rear, left, and right, respectively.

[0016] The motor 1 includes a case 4, a cover 5, a grommet 6, and a rotating shaft 10. The case 4 is formed in a cylindrical shape with a bottom and an opening 4A at its upper end. The rotating shaft 10 is supported by the case 4 with its axial direction aligned vertically. A stator (not shown) is press-fitted into the inner peripheral surface of the case 4. A rotor (not shown) is attached to the rotating shaft 10 and is disposed radially inward of the stator. A cover 5 is attached to the opening 4A of the case 4 to cover the opening 4A.

[0017] An annular bus bar 11 is provided above the stator. A connector 12 is provided on the bus bar 11. One end of an electric wire 13 is connected to the connector 12. The other end of the electric wire 13 is connected to a power source (not shown). The stator is provided with a plurality of coils (not shown). Power is supplied to the coils from the power source via the electric wire 13 and the bus bar 11.

[0018] FIG. 3 is a perspective view of grommet 6. FIG. 4 is a front view of grommet 6. FIG. 5 is a left side view of grommet 6. FIG. 6 is a cross-sectional view showing section II of FIG. 4. FIG. 7 is a bottom view of grommet 6. FIG. 8 is a cross-sectional view showing section II-II of FIG. 4. FIG. 9 is a cross-sectional view showing protrusions 24 and 25. FIG. 10 is a schematic view showing how grommet 6 is fitted into notch 4N. FIG. 11 is a schematic view showing how grommet 6 is fitted into notch 4N. FIG. 12 is a cross-sectional view showing how grommet 6 contacts notch 4N and cover 5. FIG. 13 is a cross-sectional view showing how protrusions 24 and 25 of grommet 6 are compressed after assembly is complete.

[0019] [Notch] The opening 4A of the case 4 has internal threads 4F (see FIG. 2) that open in the vertical direction formed at multiple locations. The cover 5 has multiple screw holes (not shown) that correspond to the internal threads 4F of the case 4. The opening 4A of the case 4 has a notch 4N (see FIG. 2). The notch 4N is provided on the front side of the case 4. The notch 4N (see FIG. 10) has an arc-shaped bottom 4B and a pair of side portions 4S that face each other in the left-right direction above the bottom 4B. The pair of side portions 4S are tapered in a direction that decreases the distance between the side portions 4S as they extend downward (see FIGS. 10 and 11). Note that in FIGS. 10 and 11, the taper angle of the side portions 4S is drawn larger than it actually is to facilitate understanding.

[0020] [Grommet] The grommet 6 is formed into a shape that fits the notch 4N. After the grommet 6 is fitted into the notch 4N, the cover 5 is placed over the opening 4A and the bolt 5B is tightened into the female thread 4F, causing the cover 5 to press against the grommet 6, and the grommet 6 comes into close contact with the notch 4N and the cover 5 (see Figures 1 and 10). The grommet 6 is provided to prevent foreign matter (such as water or dust) from entering the case 4 and to protect the electric wires 13. The grommet 6 is made of flexible resin.

[0021] The grommet 6 includes a contact portion 21 (see FIGS. 3, 5 to 8) that contacts the notch 4N, a pressing portion 22 (see FIGS. 3 to 6) that is pressed by the cover 5, and a through hole 23 (see FIGS. 3, 4, 6, and 8) into which the electric wire 13 is inserted. The grommet 6 is formed symmetrically in both the left-right direction and the front-to-back direction.

[0022] [Contact part, pressing part] The contact portion 21 has an arc-shaped bottom portion 21B (see FIGS. 3 and 5) that contacts the bottom portion 4B of the cutout portion 4N, and a pair of left and right side portions 21S that contact the side portions 4S of the cutout portion 4N. The pair of side portions 21S are tapered in a direction that decreases the distance between the side portions 21S downward (see FIGS. 3, 8, 9, and 10). The pressing portion 22 is the upper surface of the grommet 6.

[0023] [Through hole] The through holes 23 are circular holes that penetrate in the front-to-rear direction. There are four through holes 23 provided: two on the left and right near the center in the up-down direction of the grommet 6, and two above and below near the center in the left-to-right direction. The four through holes 23 are arranged symmetrically both left-to-right and up-to-down. The number and arrangement of the through holes 23 may differ from those in this embodiment.

[0024] [Grooves, convex parts] A groove 21G (see FIGS. 3, 5 to 8) is provided in the center of the front-rear direction of the contact portion 21 (bottom portion 21B and side portion 21S) along a direction intersecting the penetration direction (front-rear direction) of the through-hole 23. Linear protrusions 24 are provided in the groove 21G at multiple locations in the penetration direction, extending along a direction intersecting the penetration direction of the through-hole 23. In this embodiment, the protrusions 24 are provided at three locations in the penetration direction, but any number of protrusions 24 may be provided.

[0025] A groove 22G (see FIGS. 3, 5, and 6) is also provided in the center of the pressing portion 22 in the front-rear direction, extending along a direction intersecting the penetration direction (front-rear direction) of the through-hole 23. Linear protrusions 25 are provided in the groove 22G in a plurality of locations, the same number as the protrusions 24, extending along a direction intersecting the penetration direction of the through-hole 23. The three protrusions 24 of the contact portion 21 and the three protrusions 25 of the pressing portion 22 are disposed at the same positions in the penetration direction and are connected to each other (see FIG. 3). In other words, the protrusions 24 and the protrusions 25 are provided around the entire circumference of the grommet 6 in the circumferential direction intersecting the penetration direction.

[0026] A cross section of the protrusion 24 perpendicular to the circumferential direction (see FIG. 9) has a pair of upright front and rear side portions 24S and an arch portion 24A formed in an arch shape connecting the upper ends of the pair of side portions 24S. The arch portion 24A protrudes beyond the outer contact surface 21C of the groove portion 21G of the contact portion 21 (see FIGS. 6 and 8).

[0027] Similarly, a cross section of the protrusion 25 perpendicular to the circumferential direction (see FIG. 9) has a pair of upright front and rear side portions 25S and an arch portion 25A formed in an arch shape connecting the upper ends of the pair of side portions 25S. The arch portion 25A protrudes beyond the outer contact surface 22C of the groove portion 22G of the pressing portion 22 (see FIG. 6).

[0028] [Small diameter section] The through hole 23 has a standard portion 23N having an inner diameter of a standard value, a small-diameter portion 23S having an inner diameter smaller than that of the standard portion 23N, and a large-diameter portion 23L having an inner diameter larger than that of the standard portion 23N. The small-diameter portions 23S are provided at positions corresponding to one or more of the protrusions 24 of the through hole 23 (see FIGS. 6 and 8). Specifically, the small-diameter portions 23S are provided at positions corresponding to two of the multiple protrusions 24 that are not adjacent to each other. In this embodiment, the small-diameter portions 23S are provided at positions corresponding to the front-most and rear-most protrusions 24 of the three protrusions 24. The inner surface of the small-diameter portion 23S bulges inward of the through hole 23 in a direction intersecting the through hole penetration direction. The inner diameter of the position corresponding to the central protrusion 24 of the three protrusions 24 is equal to that of the standard portion 23N. The large-diameter portions 23L are provided in sections of a predetermined length from both the front and rear ends of the through hole 23. The standard portion 23N is provided between the front large diameter portion 23L and the small diameter portion 23S, and between the rear large diameter portion 23L and the small diameter portion 23S.

[0029] [Flange] The grommet 6 has flanges 26 (see FIGS. 3 to 8) that face at least one of the outer surface and inner surface of the case 4 around the notch 4N. In this embodiment, the flanges 26 are provided in front of and behind the contact portions 21 and face the outer surface and inner surface of the case 4 around the notch 4N. The flanges 26 are provided to prevent the grommet 6 from falling off the case 4 and to improve the waterproofing of the motor 1. For this reason, it is desirable for the flanges 26 to be in close contact with the outer surface and inner surface of the case 4 around the notch 4N, and the distance between the front and rear flanges 26 is substantially equal to the width in the front-to-rear direction of the contact surface 4C (see FIG. 12) that contacts the contact portion 21 of the grommet 6 at the notch 4N.

[0030] When assembling the motor 1, the rotating shaft 10, stator, coil, rotor, busbar 11, connector 12, etc. are assembled into the case 4, and then the grommet 6 and cover 5 are attached. Next, the electric wire 13 is inserted into the through hole 23 of the grommet 6, and one end of the electric wire 13 is connected to the connector 12. Next, the grommet 6 is fitted into the cutout 4N (see FIGS. 10 and 11), and the cover 5 is placed over the opening 4A (see FIG. 12). At this time, the arch portion 24A of the convex portion 24 provided in the groove 21G of the contact portion 21 contacts the contact surface 4C of the cutout 4N, and the arch portion 25A of the convex portion 25 provided in the groove 22G of the pressing portion 22 contacts the underside of the cover 5.

[0031] Next, bolt 5B is inserted into female thread 4F through a screw hole (not shown) in cover 5. As bolt 5B is tightened into female thread 4F, the pressure applied by cover 5 to grommet 6 increases. As the pressure increases, protrusions 24 and 25 are compressed. Then, bolt 5B is tightened until contact surface 4C of notch 4N comes into contact with outer contact surface 21C of groove 21G of contact portion 21 (see FIG. 13), and the bottom surface of cover 5 comes into contact with outer contact surface 22C of groove 22G of pressing portion 22, completing the assembly of motor 1.

[0032] In this embodiment, when cover 5 is attached to opening 4A, protrusion 24 is pressed against notch 4N and compressed, but gap 24V remains around protrusion 24 within groove 21G (see FIG. 13). Protrusion 25 is also compressed, but gap 25V remains around protrusion 25 within groove 22G. Gaps 24V and 25V indicate that protrusions 24 and 25 are appropriately compressed, and good sealing properties are obtained.

[0033] In this embodiment, small diameter portions 23S are provided at positions corresponding to two non-adjacent protrusions 24 among the plurality of protrusions 24. A gap remains between the through hole 23 and the electric wire 13 between the two small diameter portions 23S, and therefore the small diameter portions 23S are pressed appropriately against the electric wire 13 (not shown), thereby suppressing friction between the electric wire 13 and the through hole 23.

[0034] 14 is a cross-sectional view showing the state in which the protrusions 24, 25 of a conventional grommet 6 are compressed. In this example, no gap 24V remains around the protrusion 24 in the groove 21G, and no gap 25V remains around the protrusion 25 in the groove 22G. In this case, excessive compression of the protrusions 24, 25 may damage the grommet 6. Furthermore, the small diameter portion 23S may apply excessive pressure to the electric wire 13 (not shown), which may damage the coating of the electric wire 13.

[0035] An O-ring design method may be applied to achieve a state in which the protrusions 24 and 25 are appropriately compressed. The filling rate n [%] of the O-ring is expressed by formula (1). n=(π W 2 / 4·G·H)×100 ···(1) W [mm]: O-ring thickness (wire diameter) G [mm]: groove width H [mm]: Groove depth

[0036] In this embodiment, the thickness W of the O-ring is replaced by the cross-sectional area of ​​the multiple protrusions 24, 25. The groove width G is the width of grooves 21G, 22G, and the groove depth H is the depth of grooves 21G, 22G. For example, by setting the cross-sectional area of ​​protrusions 24, 25 and the width and depth of grooves 21G, 22G so that the filling rate n is 75% or more and 95% or less, it is possible to achieve a state in which protrusions 24, 25 are appropriately compressed.

[0037] 15 is a schematic diagram showing a conventional grommet 6. In this example, a pair of side portions 4S of the cutout portion 4N are parallel, and a pair of side portions 21S of the contact portion 21 of the grommet 6 are also parallel. In this case, when the grommet 6 is pressed downward by attaching the cover 5, pressure is generated on the side portions 21S due to the Poisson effect.

[0038] On the other hand, in this embodiment, as described above, the notch 4N and the contact portion 21 are tapered (see FIG. 10), so when the grommet 6 is pushed downward by attaching the cover 5, the downward force F has a component F1 perpendicular to the side portion 21S and a component F2 parallel to the side portion 21S, and of these, the perpendicular component F1 acts on the side portion 4S. Therefore, in addition to the pressure due to the Poisson effect similar to the conventional configuration, pressure due to the perpendicular component F1 is generated, resulting in improved sealing performance compared to the conventional configuration.

[0039] The grommet 6 according to the present embodiment described above includes a contact portion 21 that contacts a notch 4N provided in the opening 4A of the case 4, a pressing portion 22 that is pressed by the cover 5 that closes the opening 4A, a through hole 23 into which the electric wire 13 is inserted, a groove 21G provided in the contact portion 21 along a direction intersecting the through-hole 23's penetration direction, and a linear protrusion 24 provided in the groove 21G along a direction intersecting the through-hole 23's penetration direction. When the cover 5 is attached to the opening 4A, the protrusion 24 is pressed against the notch 4N and compressed, leaving a gap 24V around the protrusion 24 within the groove 21G. This configuration prevents damage to the grommet 6 due to excessive compression. Furthermore, the force F required to press the cover 5 during assembly is small, improving the ease of assembly.

[0040] Furthermore, in grommet 6 according to this embodiment, protrusions 24 are provided at multiple locations in the penetration direction, and small diameter portions 23S having a small inner diameter are provided at positions corresponding to one or more protrusions 24 of through hole 23. With this configuration, when protrusion 24 is pressed against notch 4N, small diameter portion 23S is pushed inward and pressed against electric wire 13, thereby improving the adhesion between grommet 6 and electric wire 13.

[0041] Furthermore, in the grommet 6 according to this embodiment, the protrusions 24 are provided at three or more locations in the penetration direction, and the small diameter portions 23S are provided at positions corresponding to two of the multiple protrusions 24 that are not adjacent to each other. With this configuration, a gap remains between the through hole 23 and the electric wire 13 between the two small diameter portions 23S, preventing damage to the grommet 6 due to excessive compression. Furthermore, only a small force F is required to press the cover 5 during assembly, improving the ease of assembly.

[0042] Furthermore, the grommet 6 according to this embodiment is provided with a flange 26 that faces at least one of the outer surface and the inner surface of the case 4 around the notch 4N. This configuration can improve the waterproofness of the grommet 6.

[0043] Furthermore, the motor 1 according to this embodiment includes the grommet 6, the cover 5, and the case 4. This configuration can prevent damage to the grommet 6 due to excessive compression. Furthermore, only a small force F is required to press the cover 5 during assembly, improving the ease of assembly.

[0044] Furthermore, in the motor 1 according to this embodiment, the notch 4N and the contact portion 21 are tapered. With this configuration, when the cover 5 is attached to the case 4, the contact portion 21 is pressed against the notch 4N by a component F1 of the force F that the cover 5 applies to the grommet 6, which is perpendicular to the contact portion 21, thereby improving waterproofing. Furthermore, the grommet 6 can be easily inserted into the notch 4N, improving assembly workability. Furthermore, the intersection of the opening 4A and the notch 4N forms an obtuse angle, which reduces damage to the grommet 6 when it is inserted into the notch 4N.

[0045] The above embodiment may be modified as follows.

[0046] In the above embodiment, an example in which the protrusions 24 are provided at a plurality of positions in the penetration direction has been shown, but the protrusion 24 may be provided at one position in the penetration direction.

[0047] In the above embodiment, an example has been shown in which the notch 4N and the contact portion 21 are tapered, but the notch 4N and the contact portion 21 do not have to be tapered.

[0048] <Additional Notes> The above embodiment can be specified as follows.

[0049] <Appendix 1> a contact portion that contacts a notch provided in an opening of the case; a pressing portion that is pressed by a cover that closes the opening; a through hole into which an electric wire is inserted; a groove portion provided in the contact portion along a direction intersecting the penetration direction of the through hole; a linear protrusion provided in the groove along a direction intersecting the penetration direction, A grommet characterized in that, when the cover is attached to the opening, the convex portion is pressed against the cutout portion and compressed, leaving a gap around the convex portion within the groove portion.

[0050] <Appendix 2> The protrusions are provided at a plurality of locations in the penetration direction, The grommet described in Appendix 1, characterized in that a small diameter portion with a small inner diameter is provided at a position of the through hole corresponding to one or more of the protrusions.

[0051] <Appendix 3> The protrusions are provided at three or more locations in the penetration direction, The grommet described in Appendix 2, characterized in that the small diameter portion is provided at a position corresponding to two of the multiple protrusions that are not adjacent to each other.

[0052] <Appendix 4> 4. The grommet according to claim 1, further comprising a flange portion facing at least one of the outer surface and the inner surface of the case around the notch.

[0053] <Appendix 5> A grommet according to any one of appendices 1 to 4; A rotating electric machine comprising the cover and the case.

[0054] <Appendix 6> 6. The rotating electric machine according to claim 5, wherein the notch and the contact portion are tapered. [Explanation of symbols]

[0055] 1. Motor (rotating electric machine) 4 cases 4A opening 4N Notch 5 Cover 13 Electric wire 21 Contact part 21G Groove 22 Pressing section 23 Through hole 23S Small diameter section 24 Convex part 24V gap 26 Tsuba

Claims

1. a contact portion that contacts a notch provided in an opening of the case; a pressing portion that is pressed by a cover that closes the opening; a through hole into which an electric wire is inserted; a groove portion provided in the contact portion along a direction intersecting the penetration direction of the through hole; a linear protrusion provided in the groove along a direction intersecting the penetration direction, A grommet characterized in that, when the cover is attached to the opening, the convex portion is pressed against the cutout portion and compressed, leaving a gap around the convex portion within the groove portion.

2. The protrusions are provided at a plurality of locations in the penetration direction, The grommet according to claim 1, wherein the through hole is provided with a small diameter portion having a small inner diameter at a position corresponding to one or more of the protrusions.

3. The protrusions are provided at three or more locations in the penetration direction, The grommet according to claim 2, wherein the small diameter portions are provided at positions corresponding to two of the plurality of protrusions that are not adjacent to each other.

4. 4. The grommet according to claim 1, further comprising a flange portion facing at least one of the outer surface and the inner surface of the case around the notch.

5. The grommet according to claim 1; A rotating electric machine comprising the cover and the case.

6. 6. The rotating electric machine according to claim 5, wherein the notch and the contact portion are tapered.

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