Steering shaft grommet

Abstract

To provide a grommet capable of inhibiting occurrence of involution of a cup seal at a time of abutting against a dash panel and contributing to upgrading of efficiency in molding work of the grommet.SOLUTION: A grommet 1 that covers a steering shaft 6 is interposed between a dash panel 9 and steering gear box 3. The grommet includes an attachment proximal part 20 that is engaged with the steering gear box 3 and sheathes the steering gear box, a cylindrical part 21, and a cup seal 22 that presses and abuts against the perimeter of a shaft insertion hole 9a of the dash panel 9. The cup seal has a toric seal part 22c, which abuts against the dash panel, on an end surface of an open end 22b on the periphery of the cut seal. An arc-shaped reinforcement rib 23 is formed on an internal surface of the cup seal on the side of a short-diameter side end 22d which is present at least on an early stage of abutment when the seal part is abutted against the dash panel.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a grommet for a steering shaft in a vehicle, and more particularly to a cylindrical grommet that is interposed between a dash panel that separates an engine compartment from a passenger compartment and a steering gear box, and through which a steering shaft passes. [Background technology]

[0002] An example of this type of steering shaft grommet is described in Patent Document 1. This type of grommet is also called a steering hole cover or a steering shaft cover because it is a cylindrical grommet that covers the steering shaft that passes through a hole formed in the dash panel.

[0003] FIG. 1 is a schematic explanatory diagram of a grommet according to the present invention and a conventional grommet in a properly assembled state, FIG. 10 is an explanatory diagram showing the direction in which the grommet abuts against the dash panel during assembly, FIG. 11(a) is a vertical cross-sectional view of the conventional grommet, and FIG. 11(b) is an enlarged view of part A in FIG. 11(a).

[0004] A conventional grommet 40 is formed as a single unit from a flexible rubber material, and is interposed, for example, as shown in FIG. 1, between a dash panel 9 that separates an engine room 7 from a passenger compartment 8 and a steering gear box 3. As shown in FIG. 11(a), the grommet is provided with a mounting base 41 that is fitted onto the end of the steering gear box 3, a cylindrical tubular portion 42 that is formed as a single unit with the mounting base 41 and covers the periphery of the steering shaft 6, and a large-diameter annular cup seal 43 that is provided as a single unit with the end of the tubular portion 42 and abuts against the edge of the shaft insertion hole 9a of the dash panel 9 from the engine room 7 side to provide a seal.

[0005] 11(a), the cup seal 43 has a disk-shaped maximum diameter portion 43a, an annular open end 43b facing the dash panel 9, and an annular seal portion 43c formed integrally with the outer periphery of the end face of the open end 43b and abutting against the vicinity of the edge of the shaft insertion hole 9a in the dash panel 9. The cup seal 43 also has a flange portion 44 formed integrally with the inner periphery of the seal portion 43c. The flange portion 44 is disk-shaped and extends around the entire inner periphery of the open end 43 of the cup seal 43, thereby increasing the rigidity of the entire cup seal 43.

[0006] That is, when assembling grommet 40 to dash panel 9, cup seal 43 of grommet 40 is brought into contact with abutment surface 9b near the edge of shaft insertion hole 9a of dash panel 9 at a predetermined angle θ indicated by the solid arrow with respect to a perpendicular line (dotted chain line) to abutment surface 9b, as shown in FIG. 10 . Therefore, the portion of cup seal 43 that first contacts abutment surface 9b of dash panel 9 is minor diameter portion 43d, which has a short radial length. At this time, there is a risk that minor diameter portion 43d may bend and bend inward from its outer edge, as indicated by the white arrow in the figure. Therefore, in the prior art, flange portion 44 is provided to increase the rigidity of the entire cup seal 22 and prevent the minor diameter end portion 43d from being rolled inward. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 5162558 (Figure 6) Summary of the Invention [Problem to be solved by the invention]

[0008] However, although the conventional grommet 40 can prevent inward rolling during assembly by the disk-shaped flange portion 44, this flange portion 44 becomes an undercut when the grommet 40 is removed vertically after molding, which can make it difficult to remove (demold) the mold that molds the cup seal 22. Therefore, a method has been adopted in which, after molding, high-pressure air is blown into the cup seal 43 from inside the mounting base 41 using an air demolding device, thereby expanding and deforming the entire cup seal 43, thereby allowing for demolding. This makes the molding process for the grommet 40 complicated, inevitably reducing the efficiency of the molding process and increasing the molding costs.

[0009] The present invention was devised in consideration of these conventional technical problems, and aims to provide a grommet that can improve the efficiency of the grommet molding process while suppressing the occurrence of the cup seal being rolled inward when assembled to the dash panel. [Means for solving the problem]

[0010] The invention according to claim 1 of the present application is a steering gear box that is interposed between a dash panel that separates an engine room from a passenger compartment and a steering gear box, and through which a steering shaft that is connected to the steering gear box passes. Made of flexible material A cylindrical grommet, a mounting base that is fitted onto an end of the steering gear box; a cylindrical portion formed integrally with the mounting base and covering the periphery of the steering shaft; a cup seal provided integrally with the end of the cylindrical portion opposite the mounting base portion, the cup seal having an annular seal portion on its outer periphery that abuts against one side surface of the dash panel facing the engine compartment; Equipped with When the seal portion of the inner circumferential surface of the cup seal is brought into elastic contact with the one side surface of the dash panel, at least at the initial stage of contact becomes On the inner circumferential surface of the contact portion, flexible material Reinforcement ribs togetherIt is characterized by the fact that it has been established. [Effects of the Invention]

[0011] According to the invention described in claim 1, it is possible to improve the efficiency of the grommet molding process and reduce costs while suppressing the occurrence of the cup seal being rolled inward when the grommet is assembled to the dash panel. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic explanatory diagram of a grommet according to the present invention and a conventional grommet in a properly assembled state; [Figure 2] 1 is a vertical cross-sectional view showing a first embodiment of a grommet according to the present invention. [Figure 3] FIG. 2 is a bottom view of the grommet of the present embodiment. [Figure 4] FIG. 4 is a vertical cross-sectional view showing a second embodiment of a grommet according to the present invention. [Figure 5] FIG. 2 is a bottom view of the grommet of the present embodiment. [Figure 6] FIG. 10 is a vertical cross-sectional view showing a third embodiment of a grommet according to the present invention. [Figure 7] FIG. 2 is a bottom view of the grommet of the present embodiment. [Figure 8] FIG. 10 is a vertical cross-sectional view showing a fourth embodiment of a grommet according to the present invention. [Figure 9] FIG. 2 is a bottom view of the grommet of the present embodiment. [Figure 10] FIG. 10 is an explanatory diagram showing the direction in which the grommet abuts against the dash panel during assembly. [Figure 11] (a) is a longitudinal cross-sectional view of a conventional grommet, and (b) is an enlarged view of part A in (a). DETAILED DESCRIPTION OF THE INVENTION

[0013] As mentioned above, FIG. 1 is a schematic explanatory diagram of the grommet according to the present invention in a properly assembled state, FIG. 2 is a vertical cross-sectional view showing a first embodiment of the grommet according to the present invention, and FIG. 3 is a bottom view of the grommet according to this embodiment.

[0014] As shown in Fig. 1, a vehicle steering device to which grommet 1 of this embodiment is applied includes a steering wheel 2, a steering gear box 3 of, for example, a rack-and-pinion type as a steering mechanism, and first to third steering shafts 4, 5, and 6 that connect the steering wheel 2 and the steering gear box 3. The third steering shaft 6 is inserted through a shaft insertion hole 9a provided in a dash panel 9 that separates an engine compartment 7 from a passenger compartment 8. The grommet 1 is provided between the dash panel 9 and the steering gear box 3, covering the periphery of the third steering shaft 6 from the engine compartment 7.

[0015] The first to third steering shafts 4 to 6 are interconnected via universal joints 10 and 11. The front end of the third steering shaft 6 is connected to a pinion 12 in the steering gear box 3. The pinion 12 is engaged with a rack shaft 13 that is provided so as to be able to reciprocate in the vehicle width direction, and both ends of the rack shaft 13 are connected to the knuckle arms of the left and right front wheels via tie rods, so that the left and right front wheels are steered in response to the rotation of the steering wheel 2.

[0016] An electric motor (not shown) is provided on the side of the steering gear box 3 to assist the driver in turning the steering wheel 2. The steering mechanism described above is not limited to the rack and pinion type, but may also be of a ball and nut type.

[0017] The grommet 1 is made of a flexible material such as rubber and has a substantially stepped cylindrical shape so that the third steering shaft 6 can be inserted therethrough and can cover the steering shaft 6, as described above.

[0018] Specifically, this grommet 1 is integrally molded by molding using a plurality of molding dies, and as shown in Figures 1 to 3, has a mounting base 20 that is fitted onto the end of the steering gear box 3, a cylindrical tubular portion 21 that is formed integrally with one axial end of the mounting base 20 and covers the periphery of the third steering shaft 6, and an annular cup seal 22 that is formed integrally with the end of the tubular portion 21 opposite the mounting base 20 and abuts against an abutment portion 9b around the hole edge of the shaft insertion hole 9a in the dash panel 9.

[0019] The mounting base 20 is formed in a cylindrical shape and has an insertion hole 20a formed therethrough, through which the third steering shaft 6 is inserted, and on the inner surface of the insertion hole 20a, multiple stages of fine seal bead portions 20b are formed, into which the end of the steering gearbox 3 is fitted.

[0020] The cylindrical portion 21 has a main body 21a that is coaxial with the mounting base 20, and a wall portion 21b that is integrally formed on the outer periphery of the main body 21a. A shaft hole 21c that is continuous with the insertion hole 20a of the mounting base 20 is formed through the main body 21a. One axial end of the wall portion 21b is joined to the outer periphery of the mounting base 20, and the other axial end is joined to the outer surface of the cup seal 22.

[0021] 2 and 3, cup seal 22 is formed in a generally funnel shape, with a disk-shaped maximum diameter portion 22a located in the middle in the height direction that is relatively thin and flexible and easily deformable, and an open end 22b that faces dash panel 9 is formed in a generally elliptical shape. In addition, an annular seal portion 22c that elastically contacts a contact surface 9b of dash panel 9 is provided on the outer periphery of the end face of open end 22b.

[0022] As shown in FIG. 1, when grommet 1 having such a basic configuration is properly assembled to steering gear box 3, third steering shaft 6 protruding from steering gear box 3 faces into passenger compartment 8 through shaft insertion hole 9a in dash panel 9, and therefore grommet 1 covers the portion of third steering shaft 6 that is on the engine compartment 7 side and close to dash panel 9.

[0023] In this state, mounting base 20 of grommet 1 is fitted onto the end of steering gearbox 3, thereby being held by steering gearbox 3, and cup seal 22 is mainly flexibly or compressively deformed in the axial direction (a direction perpendicular to the surface of dash panel 9) between steering gearbox 3 and dash panel 9, so that seal portion 22c of cup seal 22 elastically contacts abutment surface 9b around shaft insertion hole 9a of dash panel 9. This seals the gap between shaft insertion hole 9a of dash panel 9 and steering gearbox 3, ensuring airtightness, watertightness, and sound insulation.

[0024] In addition, while the mounting base 20 and the cylindrical portion 21 of the grommet 1 are both formed concentrically, the center line (axis) P2 of the cup seal 22 in Fig. 2 is set to intersect with the center line (axis) P1 of the cylindrical portion 21 at a predetermined angle θ1. Therefore, the cup seal 22 is formed integrally with the mounting base 20 and the cylindrical portion 21 in a manner that is inclined relative to them.

[0025] As shown in Figures 2 and 3, the cup seal 22 has a reinforcing rib 23 integrally formed on the inner surface of the short diameter side portion 22d of the inner surface of the open end portion 22b, which is the portion that first comes into contact with the contact surface 9b around the shaft insertion hole 9a of the dash panel 9 when the cup seal 22 is assembled to the dash panel 9.

[0026] The reinforcing rib 23 is formed inside the seal portion 22c in an arc shape extending from the center line P of the minor diameter portion 22d of the open end 22b along the circumferential direction of the inner peripheral surface in the left-right direction by a predetermined length L. In other words, the reinforcing rib 23 is not formed on the entire inner peripheral surface of the open end 22b, but on the minor diameter portion 22d that first comes into contact with the dash panel 9 when the open end 22b is assembled to the dash panel 9. part In other words, as described above, grommet 1 is set so that center line (axis) P2 of cup seal 22 intersects with center line (axis) P1 of cylindrical portion 21 at a predetermined angle θ1, and therefore, when grommet 1 is assembled to dash panel 9, minor diameter side portion 22d comes into contact with dash panel 9 first, as shown in Fig. 10. Therefore, in order to ensure the rigidity of minor diameter side portion 22d of cup seal 22, reinforcing rib 23 is partially provided on the inner peripheral surface of minor diameter side portion 22d.

[0027] The reinforcing rib 23 has a substantially rectangular cross-sectional shape, with the outer peripheral portion 23a integrally joined to the inner surface of the open end portion 22b, and the end portion 23b on the tubular portion 21 side integrally joined to the bottom surface of the maximum diameter portion 22a, forming a solid interior.

[0028] Such an arrangement and structure of the reinforcing ribs 23 ensures the rigidity of the area of ​​the center line P on the minor diameter side portion 22d side and the area around this, as described above.

[0029] As described above, the grommet 1 in this embodiment has a short diameter side of the open end portion 22b of the cup seal 22. part Since the rigidity of the 22d side is increased by the reinforcing rib 23, when the cup seal 22 of the grommet 1 is brought into contact with the contact surface of the dash panel 9 during assembly of the components, the occurrence of inward rolling-in of the minor diameter side portion 22d, including the seal portion 22c of the cup seal 2 that first comes into contact with the dash panel 9, can be suppressed.

[0030] Furthermore, unlike the conventional technology described above, there is no need to form a continuous annular flange in the circumferential direction on the inner periphery of the open end 22b of the cup seal 22, i.e., on the inner periphery of the seal portion 22c, to ensure rigidity. This eliminates the so-called undercut that occurs when molding the grommet with a mold. Therefore, there is no need to use an air demolding device or the like to remove the undercut from the mold during demolding, making it easier to demold the molded grommet. As a result, the molding process is easier and the efficiency of the molding process is improved. [Second embodiment] 4 and 5 show a second embodiment of the present invention, in which the basic structure of the grommet 1 is the same as that of the first embodiment, but the shape of the reinforcing rib is changed.

[0031] That is, the reinforcing ribs are arranged in three separate pieces along the inner surface of the short diameter side portion 22d, with the first reinforcing rib 24 being arranged at the center line P of the short diameter side portion 22d, and the other second and third reinforcing ribs 25, 26 being arranged on both sides of the first reinforcing rib 24 with certain gaps C1, C2 between them.

[0032] The central reinforcing rib 24 has a circumferential length L1 that is slightly longer than the circumferential lengths L2, L2 of the reinforcing ribs 25, 26 on both sides, and each of its outer circumferential portions 24a to 26a is integrally joined to the inner surface of the open end portion 22b, while its end portions 24b to 26b on the cylindrical portion 21 side are integrally joined to the bottom surface of the maximum diameter portion 22a, forming a solid interior. Therefore, the first to third reinforcing ribs 24 to 26 ensure sufficient rigidity on the minor diameter side portion 22d side.

[0033] Therefore, according to the grommet 1 of the second embodiment, as in the first embodiment, when the cup seal 22 of the grommet 1 is brought into contact with the contact surface of the dash panel 9, the minor diameter side of the cup seal 2 part Inward rolling on the 22d side can be suppressed, and the absence of an undercut portion makes it easier to remove the molded grommet from the mold.

[0034] Furthermore, by providing the gaps C1, C2 between the reinforcing ribs 24 to 26, the minor diameter portion 22d can be easily flexed and deformed even if only slightly, which improves the ease of assembling (contacting) the grommet 1 to the dash panel 9. This makes it easier to assemble the grommet 1. [Third embodiment] 6 and 7 show a third embodiment of the present invention, which is based on the second embodiment and has a configuration in which the minor diameter side of the cup seal 22 is part The long diameter side is located symmetrically on the opposite side of 22d in the radial direction. part Three reinforcing ribs 27, 28, and 29 are also formed on the 22e side.

[0035] The reinforcing ribs 27 to 29 have the same circumferential lengths L1 and L2 and cross-sectional shapes as the reinforcing ribs 24 to 26 of the second embodiment, and gaps C3 and C4 are formed between the reinforcing ribs 27 to 29. part The two reinforcing ribs 25, 26 located away from the center line P on the 22d side and adjacent to the long diameter side part Between the two reinforcing ribs 28 and 29 on the 22e side, gaps C5 and C6 are formed which are longer in the circumferential direction than the other gaps C1 to C4.

[0036] Therefore, according to the third embodiment, the six reinforcing ribs 24 to 26 and 27 to 29 reinforce the short diameter side. part 22d side and long diameter side part Since the rigidity on the 22e side is increased, the rigidity of the entire cup seal 22 (open end 22b) is increased.

[0037] Therefore, as in the second embodiment, the minor diameter side of the cup seal 2 part 22d can be prevented from being rolled inward, and the molded grommet can be easily released. part Since the rigidity of the 22e side is also increased, the contact force of the entire cup seal 22 of the grommet 1 against the dash panel 9 increases, allowing the seal portion 22b to be strongly pressed against the contact surface 9b of the dash panel 9, further improving the sealing performance around the shaft insertion hole 9a.

[0038] Furthermore, gaps C1 to C6 are formed between the reinforcing ribs 24 to 29, which allows the cup seal 22 to bend and deform easily through the gaps C1 to C6. This allows the grommet 1 (cup seal 22) to flexibly conform to the contact surface of the dash panel 9, improving the ease of assembly to the dash panel 9. In particular, the large lengths of the gaps C5 and C6 make it easy to bend the cup seal 22 at its center, further improving the ease of assembly. [Fourth embodiment] 8 and 9 show a fourth embodiment of the present invention, in which a plurality of reinforcing ribs 30a, 30b are formed with a plurality of gaps Cn over the entire inner circumferential surface of the open end 22b of the cup seal 22. Each reinforcing rib 30a, 30b has the same cross-sectional shape and is solid as those of the first to third embodiments, but differs in that their circumferential lengths are different, with some reinforcing ribs 30a having a long circumferential length L3 and other reinforcing ribs 30b having a short circumferential length L4, and these ribs are arranged intermittently and continuously in the circumferential direction in a mixed state.

[0039] Therefore, this fourth embodiment also achieves the same effects as the first to third embodiments described above, and in particular, since each reinforcing rib 30a, 30b is arranged intermittently across the entire inner surface of the cup seal 22 via a gap Cn, the rigidity of the entire cup seal 22 can be increased and flexible deformation can be ensured.

[0040] This improves the ease of assembly to dash panel 9, and also improves the sealing performance of seal portion 22b around shaft insertion hole 9a because cup seal 22 abuts dash panel 9 with a substantially uniform pressure around the entire circumferential direction. As a result, even if water pressure due to water hammer acts from the steering gear box 3 side toward grommet 1, seal portion 22b can prevent water from entering the interior.

[0041] It goes without saying that primary watertightness is provided between the steering gear box 3 and the mounting base 20 of the grommet 1 by the sealing function of the seal bead portion 20b.

[0042] The present invention is not limited to the configurations of the above-described embodiments, and for example, the cross-sectional shape of each reinforcing rib can be further changed to a triangle or the like, and any shape is acceptable as long as it ensures the rigidity of the cup seal and does not result in an undercut during mold molding. [Explanation of symbols]

[0043] 1...Grommet 2...Steering wheel 3...Steering gearbox 4...First steering shaft 5...Second steering shaft 6...Third steering shaft 7...Engine room 8…Vehicle compartment 9...Dash panel 9a...Shaft insertion hole 9b…Abutment surface 20...Mounting base 21...Cylindrical part 22...Cup seal 22a...Maximum diameter part 22b...Open end 22c...Seal part 22d...Shorter diameter end (initial contact area) 22e...Long diameter end 23...Reinforcing rib 24~26...Reinforcing rib 27~29...Reinforcing rib C...Gap

Claims

1. A cylindrical grommet made of a flexible material, interposed between a dash panel separating an engine room from a passenger compartment and a steering gear box, through which a steering shaft connected to the steering gear box passes, a mounting base that is fitted onto an end of the steering gear box; a cylindrical portion formed integrally with the mounting base and covering the periphery of the steering shaft; a cup seal provided integrally with the end of the cylindrical portion opposite the mounting base portion, the cup seal having an annular seal portion on its outer periphery that abuts against one side surface of the dash panel facing the engine compartment; Equipped with A steering shaft grommet characterized in that a reinforcing rib made of flexible material is integrally provided on the inner surface of the cup seal, at least on the inner surface of the contact area that becomes the initial contact area when the seal portion is elastically contacted with one side of the dash panel.

2. 2. The steering shaft grommet according to claim 1, 10. A grommet for a steering shaft, wherein the reinforcing rib is formed in an arc shape along the inner peripheral surface of the cup seal on the contact portion side.

3. 2. The steering shaft grommet according to claim 1, A steering shaft grommet characterized in that the reinforcing ribs are provided on the inner surface of the cup seal other than the contact area side, in addition to the contact area side of the cup seal, with a predetermined gap between them in the circumferential direction.

4. 2. The steering shaft grommet according to claim 1, A steering shaft grommet, characterized in that a plurality of the reinforcing ribs are provided at predetermined intervals in the circumferential direction on the entire inner peripheral surface of the cup seal.

5. 5. The steering shaft grommet according to claim 4, A grommet for a steering shaft, wherein the plurality of reinforcing ribs have different circumferential lengths.

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