JP3435792B2 - Sealing device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealing device.
The seal device of the present invention is applied to, for example, an ignition device for an internal combustion engine. 2. Description of the Related Art Japanese Patent Application Publication No. 4-402 filed by the present applicant.
No. 57 discloses an ignition device for an internal combustion engine. In this ignition device for an internal combustion engine, a control circuit part with a terminal is housed together with a coil part in a case in which a connector cylinder part is integrally formed, and after this terminal is made to protrude from the connector cylinder part, it is cast into the case. It is formed by casting resin. In addition, a bush made of an elastic body is fitted to the terminal in advance, and this bush is tightly attached to the inner peripheral surface of the cylindrical portion of the connector tube portion to seal the inside of the case.
Further, a lip is formed on the outer periphery of the bush, and the elastic deformation of the lip prevents resin leakage to the connector tube portion side. [0003] In the above-mentioned conventional apparatus, the bush has a circular cross section in the radial direction. However, in order to increase the number of poles of the terminal while suppressing an increase in the total cross sectional area of the bush. Preferably, the radial cross section of the bush is somewhat square. The inventors of the present invention have conducted tests on a square cross section in which the corners of the bush have been chamfered to some extent, and have found that the following problems occur. [0004] For simplicity, this problem will be described with an example of a bush having a substantially square cross section (see FIG. 5). FIG. 5 shows an enlarged front view of a corner portion of the bush 100. However, in FIG. 5, the radial dimension of the lip 101 is shown in an enlarged view for easy understanding. The dashed line P indicates the inner peripheral surface of the fitting surface portion of the connector tube portion (not shown) of the case.
Reference numeral 102 denotes an axial direction of an outer peripheral portion of the bush 100 indicated by a solid line, and reference numeral 103 denotes a lip 10 indicated by a solid line.
The top line of 1 is shown in the axial direction. Naturally, the lip 101 is formed around the bush. FIG. 5 shows a state before the bush 100 is pressed into the fitting surface of the connector tube, and the lip 101 is not elastically deformed. Also, in FIG. 5, it is assumed that the axis Mb of the bush coincides with the axis Mc of the fitting surface of the connector tube. However, when the bush 100 is actually press-fitted into the connector cylinder while the lip 101 and the like are elastically deformed, it is impossible to exactly match the two axes Mc and Mb. M
This is performed in a state where c and Mb are eccentric in a predetermined direction by a predetermined distance. For example, in the bush and the connector cylinder shown in FIG. 5, both axes Mc and Mb are aligned in the vertical direction in which one pair of sides of the connector cylinder extends, and in the other direction of the connector cylinder. Consider a case in which the pair of sides are displaced by the same distance Δd and fitted in the horizontal direction in which the pair of sides extend. The corners in this case are shown enlarged in FIG.
However, the outer periphery of the lip should not originally be able to bulge outward from the inner peripheral surface (that is, the alternate long and short dash line P) of the connector tube portion. However, FIG. It is shown positioned radially outside the inner peripheral surface (dot-dash line P) of the cylindrical portion. [0007] In FIG. 6, a dotted line D indicates both axes Mc, M
When b coincides, the position of the outer periphery (top line) of the lip (before elastic deformation) 101 is shown in the axial direction, and the dashed line P is
5 shows an inner peripheral surface of a fitting surface portion of a connector tubular portion (not shown) of a case. The solid line shows the outer peripheral portion 102 of the bush 100 and the top line 103 (before elastic deformation) of the lip 101 when the axis Mb is displaced by the displacement vector V from the original position, that is, the axis Mc of the connector cylinder. As can be seen from FIG. 6, the top line 103 of the lip 101 still protrudes outside the inner peripheral surface of the connector tube portion indicated by the dashed line P at the side of the lip 101, and the elasticity of this protruding portion Although the seal is secured by the deformation, the top line 103 of the lip 101
At the corner of the lip 10, the lip 10 is almost overlapped with the inner peripheral surface of the connector tubular portion indicated by the dashed line P.
It was found that sealing at the corner of No. 1 by elastic deformation of the lip 101 could not be expected. More specifically, with reference to the displacement vector V in FIG. 6, the vertical and horizontal sides of the lip 101 are displaced by the displacement vectors Vv and Vh, respectively. Absolute value (displacement distance) Vo of displacement vectors Vv and Vh
Are equal because the displacement is oblique by 45 degrees, and as a result, the absolute value (displacement distance) of the displacement vector V at the corner of the lip 101
Is about 1.4 Vo. [0010] That is, the shortest distance from the top line 103 of the lip 101 to the inner peripheral surface of the connector cylindrical portion is determined by the two axial centers M
Unless c and Mb are matched, if not manufactured larger at the corners than at the sides, there is a problem that the sealing performance is deteriorated. The present invention has been made in view of the above problems, and an object of the present invention is to provide a sealing device capable of preventing a decrease in sealing performance despite having a lip having a rectangular cross section in a radial direction. And [0011] The sealing device of the present invention comprises:
The connector tube portion 5 having a square hole is integrally formed, and
A resin case 1 having a built-in road device, a lip 8 having elasticity over the entire outer peripheral portion, a rectangular projection fitted into the rectangular hole, and a terminal 7 protruding.
That a bush 6 which has a terminal hole 69, the lip 8 in the fitted state in the seal device is pressed against the mating surface of the square hole, the axial center the lip 8 of the connector tube portion 5 A corner between an outer dimension of the lip 8 having a dimension up to the outer periphery of the lip and an inner dimension of a corner of the fitting surface having a dimension from the axis of the bush 6 to the corner of the fitting surface. part pop-out amount, the re consisting dimensions up shaft center side portion outer periphery of the lip 8 of the bush 6
The protrusion amount of the side portion between the outer size of the side portion of the tap 8 and the inner size of the side portion of the fitting surface portion, which is a dimension from the axis of the connector tube portion 5 to the side portion of the fitting surface portion, The lip has a side portion 82 and a corner portion and is large.
The top 81 of the corner of the step 8
It is characterized in that it has a radius of curvature smaller than the inner peripheral surface of the barrel portion 5 . [0012] [0013] In sheet Lumpur apparatus of the present invention the effect of the action and the present invention,
The amount of protrusion of the corner between the outer dimension of the lip and the inner dimension of the mating surface of the connector tube is the outer dimension of the lip and the connector.
The protrusion is formed to be larger than the amount of the side protruding from the inner dimension of the side of the fitting surface of the tubular part . In this way, Bush and
Even if the relative displacement vector between the two axial centers of the connector and the cylindrical part of the connector is generated radially oblique to the lip or the side of the fitting surface, the leakage prevention function at the corner of the lip is prevented from deteriorating. Can be. Further, since the lip height is not increased over the entire circumference of the lip, the ease of fitting can be maintained. An embodiment of the present invention will be described with reference to a specific embodiment. FIG. 1 is a sectional view of an example applied to an ignition device for an internal combustion engine to which the present invention is applied, in particular, to a capacity discharge ignition device.
An electronic circuit device 3 mounted on a printed circuit board 2 is housed in a case 1 having a resin molded body with openings at both ends from the right end opening in the figure, and is placed on a guide ridge 10 on the inner surface of the case 1. After the electronic circuit device 3 is housed, a sealing resin (considered to be transparent) 4 is cast into the case 1 from the right end opening. In the drawing of the case 1, a connector tube portion 5 is formed integrally with the case and protrudes from the left end. The support protrusion 60 of the bush 6 is fitted into a hole (not shown) of the printed board 2, whereby the bush 6 is fixed to the printed board 2. A pair of terminals 7 each having one end soldered to the printed circuit board 2 penetrate a terminal hole 69 of the bush 6 and protrude leftward in the figure. FIG. 2 is an enlarged sectional view of a main part of FIG. The tip outer peripheral surface 61 of the bush 6 is connected to the inner peripheral surface 5 of the connector tube portion 5.
0 is tightly fitted in the narrowest part. Bush 6
Has a main outer peripheral surface 62 slightly larger in diameter than the distal end outer peripheral surface 60 adjacent to the distal end outer peripheral surface 60, and a step 63 is formed at the boundary between both outer peripheral surfaces 61, 62. When the bush 6 is fitted, the step portion 63 abuts against a step portion (stopper surface) 51 formed on the inner peripheral surface 50 of the connector tube portion 5 and the bush 6
Regulates any further protrusion. A lip 8 is formed on the main outer peripheral surface 62 of the bush 6 over the entire periphery at a position close to the outer peripheral surface 61 of the front end. When the bush 6 is fitted, the lip 8 comes into close contact with the inner peripheral surface of the connector tube portion 5 and elastically deforms to perform a lip sealing function. FIG. 3A is a front view of the case 1 (FIG. 1).
1 shows a state viewed from the right to the left, and FIG. 2B shows a front view of the bush 6 (viewed from the left to the right in FIG. 1). Terminals penetrate the bush 6 in three rows each of upper and lower two stages. Reference numeral 54 denotes a guide wall extending to the case 1 side for guiding the bush 6 to the connector tube 5, and a part of the guide wall 54 is provided with a notch 55. The formation of the notch 55 is for facilitating the insertion of the bush 6. Hereinafter, features of the present embodiment will be described with reference to FIG. However, in FIG. 4, the radial size of the lip 8 is greatly enlarged for easy understanding.
An alternate long and short dash line P indicates the inner peripheral surface (the inner peripheral surface of the fitting surface portion) 50 of the connector tube portion 5. The broken line T indicates the connector cylinder 5
The top line (outermost diameter, but without elastic deformation) of the lip 8 when the axis of the bush 6 coincides with the axis of the bush 6 is shown in the axial direction. The solid line T ′ indicates the top line (outermost diameter, but no elastic deformation) of the lip 8 in the axial direction when the axis of the bush 6 is displaced from the axis of the connector cylinder 5 by the displacement vector Vp. In this embodiment, the center of curvature Cp at the corner of the one-dot chain line P and the center of curvature Ct 'at the corner of the top line of the lip 8 after the displacement are matched. When the two centers of curvature Cp and Ct 'coincide with each other, the connector cylinder 5
The radius of curvature (in this embodiment, the radius of the circle) rp of the inner peripheral surface 50 at the corner of is calculated from the radius of curvature (in this embodiment, the radius of the circle) rt ′ of the corner of the top line T ′ of the lip 8. It is designed to be smaller by Δd. That is, in this state,
The lip 8 is uniformly Δ at both corners and sides.
It can be elastically compressed and deformed by d, and the sealing properties become substantially equal. Next, let us consider an ideal state in which both axis centers of the connector tubular portion 5 and the bush 6 coincide. Of course, at this time,
The top line of the lip 8 becomes a dashed line T, and the center of curvature of the corner becomes Ct. As a result, the top line T of the lip 8 is formed, and at the corner thereof, a shape bulging radially outward from the inner peripheral surface of the connector tube portion 5 is formed. As described above, in this embodiment, the top 81 of the corner of the lip 8 is fitted to the connector tube 5
Has a smaller radius of curvature than the inner peripheral surface of
Since the top 81 of the lip 8 protrudes more than its side 82 without eccentricity, even if the bush 6 and the lip 8 are displaced in the radial direction, the top 81 of the lip 8 leaks more easily than the top 82 of the side of the lip 8. There is no. (Modification) Another embodiment will be described below.
In the above embodiment, the radial cross sections of the connector tube portion 5 and the bush 6 are chamfered rectangles. However, other polygons having a corner may be used as long as they have corners. May be. In a state in which both axis centers of the connector tube portion 5 and the bush 6 are aligned, the angle of the connector tube portion 5 is determined from the amount of protrusion from the inner peripheral surface of the side portion of the connector tube portion 5 to the outer periphery of the side portion of the lip 8. In order to increase the amount of protrusion from the inner peripheral surface to the outer periphery of the corner of the lip 8, the following method can be adopted. First, the distance from the outer periphery of the lip 8 to the outer periphery of the corner of the bush 6, that is, the height of the lip is determined by the distance from the outer periphery of the lip 8 to the outer periphery of the side of the bush 6, that is, the side height of the lip. Increase. Alternatively, the radius of curvature of the outer periphery of the corner of the lip 8 is made smaller than the radius of curvature of the inner peripheral surface of the connector tube 5. The thickness of the lip 8 in the axial direction can be made larger at the corners 81 than at the sides 82. By doing so, the elastic deformation of the corners 81 of the lip 8 is less likely to be elastically increased, and the minimum elastic compression amount Δ of the lip 8 required for sealing is increased.
Since d can be reduced at the corner portion 81, eccentricity can be tolerated accordingly. Also, the lip 8 of the present embodiment can be applied to other sealing devices, and the bush 6 or the fitting body and the lip 8 are separated from each other, and the ring-shaped lip 8 is fitted to the fitting body 6. You can also.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of an ignition device for an internal combustion engine according to the present embodiment. FIG. 2 is an enlarged sectional view of a main part of FIG. FIG. 3 is a front view of a bush 6 and a case 1. FIG. 4 is an enlarged schematic diagram showing a state of a corner of a lip 8 of the present embodiment. FIG. 5 is a schematic front view of a conventional bush. FIG. 6 is an enlarged sectional view of a main part of FIG. 5; [Description of References] 1 is a case, 5 is a connector tube portion (fitted body), 8 is a lip, 6 is a bush (fitted body), 62 is an outer peripheral surface of the bush 6, and 7 is a terminal.

Claims (1)

(57) [Claims 1] A connector tube portion 5 having a square hole is integrally formed.
And a resin case 1 having a built-in electronic circuit device, a rectangular projection having an elastic lip 8 over the entire outer periphery and fitted into the rectangular hole, and having a terminal.
And a bush 6 having a terminal hole 69 Le 7 protrudes, the lip 8 in the fitted state in the seal device is pressed against the mating surface of the square hole, the axis of the connector tube portion 5 and the angular outer dimensions of the lip 8 of dimensions down corner periphery of the lip 8, the blanking
The amount of protrusion of a corner between an inner dimension of the fitting surface portion and a dimension from the axis of the bush 6 to the corner portion of the fitting surface portion is determined from the axial center of the bush 6 to the outer periphery of the side of the lip 8. and the side outer dimensions of the lip 8 of dimensions up, the co
Than sides pop-out amount between the fitting surface of the side portion inside dimension consisting of dimensions to the axial center side portion of the fitting surface of the connector tube portion 5 is larger, the lip, the side portions 82 And a corner, and the lip 8
The connector tube with which the top 81 of the corner is fitted
A seal device having a radius of curvature smaller than the inner peripheral surface of the portion 5 .