JP5450575B2 - Gasket with beads - Google Patents

Description

  The present invention relates to a beaded gasket in which a gasket sandwiched between two members has a bead that is formed between first and second flat surfaces and protrudes to one side of the two members.

  Patent Document 1 listed below discloses that a bead having a trapezoidal cross-sectional shape is used to improve sealing performance by forming a bowl-shaped bead on a gasket.

  In addition, Patent Document 2 below discloses that a trapezoidal cross-section bead of Patent Document 1 is changed to an arc.

  Further, the upper base portion of the trapezoidal bead of Patent Document 1 is changed to a triangle, and the triangular portion is sharpened upward by increasing the inclination angles of the two sides of the triangle more than the inclination angles of the two leg portions of the trapezoid. This is known from Patent Document 3 below.

JP-A-8-159284 Japanese Utility Model Publication No. 6-73539 JP 2001-32939 A

  By the way, as described in detail in the section “Description of Embodiments”, the above-described Patent Document 1 discloses that the upper bottom portion of the trapezoidal bead is bent downward when a compressive force is applied to the gasket. Therefore, only both ends of the upper bottom portion come into contact with one of the two members. Therefore, the width of the contact surface that exhibits the sealing function during high compression is reduced.

  Further, as described in detail in the section “Description of Embodiments”, the above-described Patent Document 2 describes that the arc-shaped portion of the bead functions as an arch even when a compressive force is applied to the gasket. In order to exhibit high rigidity, the portion is difficult to be crushed and comes into contact with one of the two members with a small contact surface. Therefore, even if the gasket is compressed, the width of the contact surface that exhibits the sealing function remains small and does not increase.

  In addition, since the trapezoidal portion of the bead with low rigidity is easily deformed and the triangular portion of the bead with high rigidity is difficult to deform when the compression force is applied to the gasket, only the vertex of the triangular portion is described in Patent Document 3 described above. It abuts on one of the two members. Therefore, even if the gasket is compressed, the width of the contact surface that exhibits the sealing function remains small and does not increase.

  If the contact width of the gasket is small, for example, if the surface to be sealed has scratches or a casting hole in the casting, the scratch or the diameter of the casting hole exceeds the contact width of the gasket and the sealing performance is impaired. there is a possibility. Further, when the surface to be sealed of a thin member is fastened with a bolt, the compression stroke of the gasket may be different between the vicinity of the seat surface of the bolt and between the seat surfaces. Even in such a case, in order to seal between the members, it is necessary to stably obtain a wide contact width from the compression initial stage (at the time of low compression) to the time of high compression.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to stably obtain a wide contact width from the initial compression stage to the high compression stage in a gasket sandwiched between two members.

In order to achieve the above object, according to the first aspect of the present invention, a gasket sandwiched between two members is formed between the first and second flat surfaces, and one side of the two members. a beaded gasket having a projecting bead, the bead, the first seen in the cross section, a first respectively a second flat surface, each flat first bending through a second bend 1, a second bead surface, the viewed in the cross section first, third, respectively the second bead surface, each flat first connecting mutually the fifth bent portion bent through the 4th bend section 3, and a fourth bead surface, wherein the first of said first bead surface of the first bent portion, the inclination angle against the second flat surface, said third bead surface in the third bent portion first 1, greater than the inclination angle against the second flat surface, put the second bend Said first of said second bead surface, the inclination angle against the second flat surface, the first of the fourth bead surface in the fourth bent portion is larger than the inclination angle against the second flat surface, the four A beaded gasket is proposed in which each of the two inclination angles is an acute angle.

  According to the structure of Claim 1, the bowl-shaped bead formed between the 1st, 2nd flat surfaces of the gasket is comprised by the 1st-4th bead surface connected by the 1st-5th bending part. The When the fifth bent portion of the bead is compressed by one member toward the other member, the bending rigidity of the first and second bent portions having a large inclination angle is the bending rigidity of the third and fourth bent portions having a small inclination angle. Therefore, the third and fourth bent portions having low bending rigidity are pushed and bent first, and the third and fourth bead surfaces become flat. Even if it is further compressed from here, the fifth bent portion is originally bent upward and convexly, so that the fifth bent portion is prevented from being bent downward and protruding away from one member, The third and fourth bead surfaces continue to contact one member throughout the entire area. As a result, a wide contact width can be stably obtained from the initial compression of the gasket to the time of high compression.

The figure which shows the gasket clamped between the mission case and the oil pan. The figure which shows the cross-sectional shape of a gasket. The graph which shows the relationship between the compression stroke of a gasket, and a contact width. The figure which shows distribution of a cross-sectional shape when a gasket is compressed, and surface pressure.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, a metal gasket G is sandwiched between a flange 11 a of a transmission case 11 of an automobile transmission and a flange 12 a of an oil pan 12, and oil in the oil pan 12 is held by the gasket G. Is sealed to prevent leakage to the outside.

  FIG. 2 shows the shape of the cross section of the gasket G. The gasket G in a free state where no load is applied is a first bead having a planar shape between the first flat surface 13A and the second flat surface 13B. A bowl-shaped bead 15 including a surface 14A, a second bead surface 14B, a third bead surface 14C, and a fourth bead surface 14D is provided. The first bent portion 16A that becomes the boundary between the first flat surface 13A and the first bead surface 14A is bent at an inclination angle θ1, and the second bent portion 16B that becomes the boundary between the second flat surface 13B and the second bead surface 14B is inclined. The third bent portion 16C that bends at the angle θ2 and becomes the boundary between the first bead 1 surface 4A and the third bead surface 14C is bent at the inclination angle θC and becomes the boundary between the second bead surface 14B and the fourth bead surface 14D. The fourth bent portion 16D is bent at an inclination angle θD, and the fifth bent portion 16E serving as a boundary between the third bead surface 14C and the fourth bead surface 14D is bent at the apex angle θE.

Note that the inclination angle θA~θD herein, is defined as an inclined angle against the first and second flat surfaces 13A, 13 B. The bead 15 of the embodiment has a bilaterally symmetric shape with respect to a plane orthogonal to the first and second flat surfaces 13A and 13B through the fifth bent portion 16E, and thus θA = θB and θC = θD. .

The bead 15 protrudes to one side of the gasket G, the inclination angle θA of the first bent portion 16A is set larger than the inclination angle θC of the third bent portion 16C (θA> θC), and the second bent portion 16B. Is set to be larger than the inclination angle θD of the fourth bent portion 16D (θB> θD). The inclination angle θA, θB, θC, θD are both are acute. Therefore, a virtual surface connecting the first flat surface 13A and the second flat surface 13B and the first to fourth bead surfaces 14A to 14D are the first to fifth bent portions 16A to 16E in the cross section of the bead 15. Convex pentagon with a vertex.

  The graph of FIG. 3 shows the compression stroke (horizontal axis) when the gasket G of the embodiment, the gasket G of the comparative example 1, and the gasket G of the comparative example 2 are sandwiched and compressed between two members. And the contact width (vertical axis). The contact width is a width of a portion where the bead 15 of the gasket G is compressed and is in close contact with one member, and it is determined that the sealing performance of the gasket G is higher as the contact width is larger in a wide compression stroke range.

  The bead 15 of the gasket G of Comparative Example 1 is shown in FIG. 4B and corresponds to that described in Patent Document 2 above. The bead 15 of the gasket G of Comparative Example 2 is shown in FIG. 4C and corresponds to that described in Patent Document 1.

  As is apparent from the table of FIG. 3, the test pieces of the embodiment, Comparative Example 1 and Comparative Example 2 have their height, width, upper height, upper width, inclination angles θ1, θ2 and inclination angles θ3. The difference between the first comparative example and the embodiment is that the third bead surface 14C and the fourth bead surface 14D of the embodiment are changed to arcs in the first comparative example. The difference of the comparative example 2 with respect to the form is that the third bead surface 14C and the fourth bead surface 14D of the embodiment are changed to one plane in the comparative example 1.

  As is clear from the graph of FIG. 3, the gasket G of the embodiment can obtain a wide contact width of 3 mm to 4 mm in a wide region where the compression stroke is 80 μm to 220 μm. The reason is that, as shown in FIG. 4A, when the fifth bent portion 16E of the gasket G is compressed downward by the upper member, the first and second bent portions 16A, 16B having large inclination angles θA, θB. Is higher than the bending rigidity of the third and fourth bent portions 16C and 16D having the small inclination angles θC and θD, so that the third and fourth bent portions 16C and 16D having the lower bending rigidity are pushed and bent first. The third and fourth bead surfaces 14C and 14D are deformed flat. Even if further compressed from here, since the fifth bent portion 16E is originally bent upward and convex, the fifth bent portion 16E is prevented from being bent upward and bent away from the upper member. This is because the third and fourth bead surfaces 14C and 14D are in contact with the upper member over the entire area to form a wide contact surface.

  On the other hand, the gasket G of Comparative Example 1 gradually increases in contact width as the compression stroke increases, but only a contact width of slightly over 1 mm can be obtained even when the compression stroke reaches 220 μm. The reason for this is that, as shown in FIG. 4B, the arc-shaped portion of the bead 15 has an arch structure and exhibits extremely high rigidity against the load from above, so that even if the compression stroke increases, the arc shape This is because is held and contacts the upper member in a small area.

  Further, the gasket G of Comparative Example 2 has a contact width of 3 mm in the vicinity of the compression stroke of 70 μm, but in a region where the compression stroke is larger than that, the contact width is greatly reduced to about 1 mm. The reason for this is that, as shown in FIG. 4C, the flat surface of the top of the bead 15 is extremely low in rigidity, so that it is easily folded downward when pressed by the upper member. Two small contact portions separated in the vicinity of the third and fourth bent portions 16C and 16D at the upper ends of the second bead surfaces 14A and 14B are formed. In the second comparative example, the flat surface of the folded top portion comes into contact with the lower member to form a new contact surface.

  The contact portion formed between the gasket G and the lower member is not much different between the embodiment, Comparative Example 1 and Comparative Example 2, and the first and second flat surfaces 13A and 13B and the first, Only two small contact portions are formed in the vicinity of the first and second bent portions 16A and 16B at the boundary with the second bead surfaces 14A and 14B.

  Further, when the compression stroke exceeds 220 μm, the contact width of any of the embodiment, Comparative Example 1 and Comparative Example 2 increases abruptly because the bead 15 of the gasket G is completely crushed. The shape becomes meaningless. In such a compression stroke region, the elasticity of the bead 15 is lost and the sealing function is lowered, so that it cannot be used.

  For example, when the gasket G is sandwiched between the flange 11a of the transmission case 11 and the flange 12a of the oil pan 12 and fastened with a bolt, the axial force increases near the bolt and the compression stroke increases, and at a position away from the bolt. Since the axial force is weakened and the compression stroke is reduced, the size of the compression stroke is not uniform in each part of the gasket G. However, according to this embodiment, since a wide contact width of 3 mm or more can be obtained in a wide region where the compression stroke is 80 μm to 220 μm, a high seal is provided over the entire circumference of the gasket G regardless of the position of the bolt. The ability to show off.

  For example, in the case of a conventional gasket, when the recess 11b (see FIG. 1) is present on the workpiece flange due to a nest during casting or machining, the diameter of the recess 11b exceeds the contact width of the bead 15 of the gasket G. The sealing performance has been significantly reduced. However, according to the present embodiment, the bead 15 of the gasket G has a very wide contact width from the initial compression stage to the high compression stage, so even if there is a recess 11b that would deteriorate the sealing performance in the prior art. High sealing performance can be exhibited.

  The embodiments of the present invention have been described above, but various design changes can be made without departing from the scope of the present invention.

  For example, the gasket with a bead of the present invention is not limited to the one used for sealing between the mission case 11 and the oil pan 12, and can be used in any place.

  In the embodiment, the inclination angle θA = the inclination angle θB and the inclination angle θC = the inclination angle θD are set. Inclination angle θA ≠ inclination angle θB or inclination angle θC ≠ inclination angle θD. That is, the cross-sectional shape of the bead 15 does not necessarily have to be symmetric with respect to a plane that passes through the fifth bent portion 16E and is orthogonal to the first and second flat surfaces 13A and 13B.

11 Mission case
12 Oil pan (member)
13A 1st flat surface 13B 2nd flat surface 14A 1st bead surface 14B 2nd bead surface 14C 3rd bead surface 14D 4th bead surface 15 bead 16A 1st bent part 16B 2nd bent part 16C 3rd bent part 16D 4th Bent portion 16E Fifth bent portion θA Inclination angle θB in first bent portion Inclined angle θC in second bent portion Inclined angle θD in third bent portion Inclined angle G in fourth bent portion Gasket

Claims (1)

A gasket (G) sandwiched between the two members (11, 12) is formed between the first and second flat surfaces (13A, 13B) and protrudes to one side of the two members (11, 12). A beaded gasket having a bead (15) that comprises:
Said bead (15), the first seen in the cross section, a second flat surface (13A, 13B) first, respectively from the second bent portion (16A, 16B) each planar first bending through the second bead surface and (14A, 14B), is bent through the first look at the same cross section, the second bead surface (14A, 14B) respectively from the third and fourth bent portion (16C, 16D) And third flat and fourth bead surfaces (14C, 14D) connected to each other at the fifth bent portion (16E),
The first of said first bent portion and the at (16A) first bead surface (14A), the inclination angle against the second flat surface (13A, 13B) (θA), the in the third bent portion (16C) the first third bead surface (14C), a second flat surface (13A, 13B) to be larger than the inclination angle (.theta.C) against,
Said first of said second bead surface in the second bent portion (16B) (14B), the inclination angle against the second flat surface (13A, 13B) (θB), said in the fourth bent portion (16D) the first fourth bead surface (14D), a second flat surface (13A, 13B) to be larger than the inclination angle (theta] D) against,
A gasket with a bead characterized in that all of the four inclination angles (θA, θB, θC, θd) are acute angles.

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