JP2011094667A - Gasket and sealing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gasket which can exhibit sealing performance without being affected by the surface state of a contact surface of a mounting counterpart, and a sealing structure. <P>SOLUTION: In a cross section of the gasket 1 along the height direction which is a compression direction and along the width direction which is a facing direction of both side surfaces of a groove, areas forming sealing surfaces in an outline of the cross section are circular parts 2 composed of convex curves toward a groove bottom surface and toward a surface of the other member in a state before the gasket 1 is compressed between two members. The gasket 1 has circular constricted parts 3 composed of concave curves in areas facing side surfaces of the groove. The circular parts 2 are composed of curves having curvatures smaller than a curvature of a cross section of a gasket having a circular cross section with approximately the same height. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a gasket and a sealing structure.

  A gasket such as an O-ring is sandwiched between two members and compressed to seal a gap between the two members. Generally, a groove for mounting a gasket is provided on one of the two members. When the gasket mounted in the groove is in close contact with the groove bottom surface and the other member surface, the gap between the two members is sealed. The gasket is deformed so as to be crushed between the two members, and the contact surface with the two members functions as a seal surface.

  The gasket exhibits sealing properties when the gasket and the two members are in close contact with each other without any gap. However, if there are irregularities on the surface of the two members, a gap may be formed between the gasket and the two members, which may cause leakage of the sealing fluid.

  A die-cast part such as an engine part may have a concave portion due to a cast hole on the finished surface. In cast parts, voids between particles may remain inside the part even after sintering to form a cast hole. The surface of the cast part may be finished by cutting in order to improve dimensional accuracy, flatness, etc., but at this time, the cast hole inside the part may be exposed to the surface by cutting to form a concave part. When the size of the concave portion is larger than the width of the sealing surface of the gasket, the sealing fluid may leak through the concave portion.

  In recent years, in order to reduce the manufacturing cost by simplifying the manufacturing process, a technique of assembling a product using a cast product is often employed. However, due to the occurrence of the above-mentioned casting hole, it is not possible to obtain sufficient sealing performance, so it is necessary to provide a number of stages of sealing, discard the product as a nonconforming product, or give up casting material There are cases like this.

  Conventionally, resin or liquid rubber (FIPG) is applied to the concave portion to seal the gap between the gasket and the cast part, or the cast part itself is replaced with a structure with less influence of the cast hole. (See Patent Document 1). However, in recent mechanical design, there is a demand for downsizing and weight reduction for the purpose of securing space and improving fuel consumption, and by increasing the downsizing, the shape of products that are difficult to form increases, and defect management in the manufacturing process Work is getting harder. Therefore, it is considered that the gasket itself needs some contrivance for countermeasures against the cast hole.

  However, most of the gaskets that have been proposed so far have been designed to reduce the reaction force and prevent falling, etc. during installation, and can be adequately handled even when the condition of the contact surface of the installation partner is poor. Absent. For example, the gasket disclosed in Patent Document 2 has a constricted shape on the side surface of the gasket to reduce reaction force at the time of mounting, and suppresses deformation on the seal surface by concentrating deformation on the constricted portion. However, since the increase in the contact width is suppressed, there is a risk of leakage if the above-described concave portion or the like is formed on the contact surface of the mating member.

JP 2001-113404 A JP 2007-107546 A

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a gasket capable of exhibiting a sealing property without being affected by the surface state of the contact surface of the mounting partner. And providing a sealing structure.

In order to achieve the above object, the gasket of the present invention comprises:
It is mounted in a groove provided in one of the two members and is compressed between the two members, thereby forming a sealing surface that closely contacts the groove bottom surface of the groove and the surface of the other member. A gasket for sealing a gap between members,
In the cross section along the height direction and the width direction, the region that forms the seal surface in the cross section along the height direction and the width direction, with the compression direction as the height direction and the direction in which both side surfaces of the groove face each other as the width direction, In a state before the gasket is compressed between the two members, each is an arc-shaped portion configured with a convex curve toward the groove bottom surface of the groove and the surface of the other member,
In the gasket having an arcuate constricted portion formed of a concave curve in a region facing the side surface of the groove,
The convex arcuate portion is formed by a curve having a curvature smaller than the curvature of the cross-section of the gasket having a circular cross-section having substantially the same height.

  In this way, by reducing the curvature of the convex arcuate part, when the gasket is compressed between the two members, the two members come into contact with each other with a crushing amount substantially equal to that of the gasket having a circular cross section in the height direction. The width of the region (seal surface) is increased. Here, the amount of crushing is the height of the gasket cross section before compression by two members, and the distance between the groove bottom surface and the other member surface in the height direction (height of the gasket cross section after compression by two members). And the difference. Thereby, the influence on the sealing performance by the condition of the contact surface of the mating member is reduced. That is, even when the groove bottom surface or the other member surface has unevenness, leakage through the unevenness can be suppressed by the enlarged seal surface covering the unevenness.

  As a case where a concave portion is formed on the groove bottom surface or the other member surface, for example, a case where both or one of the two members is a cast product and a concave portion due to a cast hole is formed on the contact surface with the gasket is considered. . In addition, for example, it is conceivable that unevenness is formed by scratching the groove bottom surface or the other member surface. In addition, as a case where unevenness arises in the contact surface with the gasket in two members, it is not limited to these cases. That is, the gasket of the present invention can be suitably used even when the contact surface of the mating member is in a surface state that is difficult to seal sufficiently with conventional gaskets.

In order to achieve the above object, the sealing structure in the present invention comprises:
Two members, both or one of which is a casting,
The gasket for sealing the gap between the two members;
It is characterized by providing.

  As described above, even when a concave portion due to a cast hole is formed on the contact surface of the two members with the gasket, the expanded sealing surface of the gasket covers the concave portion to suppress leakage through the concave portion. be able to. Therefore, the trouble by employ | adopting the above-mentioned casting product is eliminated, and it can contribute to the reduction of the number of processes, the reduction of nonconforming product, the reduction of management work, etc.

  According to the present invention, it is possible to exhibit the sealing performance without being affected by the surface state of the contact surface of the mounting partner.

It is typical sectional drawing of the gasket which concerns on the Example of this invention. It is typical sectional drawing of the sealing structure which concerns on the Example of this invention. It is typical sectional drawing of the sealing structure which concerns on the Example of this invention. It is a schematic diagram explaining the amount of crushing. It is a schematic diagram explaining the amount of crushing. It is a table | surface which shows the verification result of the performance comparison with the gasket which concerns on the Example of this invention, and the conventional O-ring. It is a table | surface which shows the verification result of the performance comparison with the gasket which concerns on the Example of this invention, and the conventional O-ring. It is a table | surface which shows an analysis result when changing a curvature radius in the gasket which concerns on the Example of this invention. It is a table | surface which shows the analysis result when changing the product core width in the gasket which concerns on the Example of this invention. It is a table | surface which shows the analysis result when changing the relationship between product core width and product width in the gasket which concerns on the Example of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

(Example)
With reference to FIGS. 1-10, the gasket and sealing structure which concern on the Example of this invention are demonstrated. FIG. 1 is a schematic cross-sectional view of a gasket according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a sealing structure (planar fixing seal) according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of a sealing structure (cylindrical surface fixing seal) according to an embodiment of the present invention. FIG. 4 is a schematic diagram illustrating the squashing amount. FIG. 5 is a schematic diagram illustrating the crushing rate. FIG. 6 is a table showing verification results of performance comparison between gaskets according to examples of the present invention and conventional O-rings. FIG. 7 is a table showing verification results of performance comparison between the gasket according to the example of the present invention and the conventional O-ring. FIG. 8 is a table showing analysis results when the curvature radius is changed in the gasket according to the example of the present invention. FIG. 9 is a table showing the analysis results when the product core width is changed in the gasket according to the embodiment of the present invention. FIG. 10 is a table showing analysis results when the relationship between the product core width and the product width is changed in the gasket according to the embodiment of the present invention.

<Gasket>
The gasket 1 according to the present embodiment is made of a rubber-like elastic body. Specific examples of the rubber-like elastic material include acrylic rubber, nitrile rubber, fluorine rubber, and the like.

  The gasket 1 according to the present embodiment is used for various devices such as automobile parts and industrial equipment. More specifically, it is used for various applications such as inlet manifolds, filter blankets, cylinder head covers, timing belt covers, and fuel cell separators. In particular, it is suitable for sealing of cast parts such as aluminum die-cast products in which a concave portion due to a cast hole is formed on the contact surface, sealing of a cast surface, sealing of a blast surface, and sealing of a machined surface.

In the various devices described above, the gasket 1 is sandwiched and compressed between two opposing surfaces having opposing surfaces facing each other to seal a gap between the two members. Generally, a groove for mounting the gasket 1 is provided on the opposing surface of one of the two members. The gasket 1 is mounted in the groove, and seals the gap between the two members by being in close contact with the groove bottom surface and the other member surface.

  As shown in FIG. 1, the gasket 1 is a cross section provided with an arc-shaped portion 2 that forms a seal surface and a constricted portion 3 for absorbing a compressive load in a cross section cut along the height direction and the width direction. It has a shape. Here, the height direction is a direction in which the gasket is compressed between the two members at the time of mounting, and the width direction is a direction in which both side surfaces of the groove in which the gasket is mounted face each other. The cross-sectional shape of the gasket 1 is configured symmetrically in the width direction about the central axis X of the cross section extending in the height direction.

  The arc-shaped portion 2 has a smaller curvature than the arc-shaped portion in the conventional gasket (O-ring) 100 having a substantially perfect circular cross section having the same product height as the gasket 1. That is, the arc-shaped portion 2 is configured with a radius of curvature ra that is larger than the radius rb of the gasket 100. Therefore, the gasket 1 has a wider contact width of the seal surface formed when the gasket 1 and the gasket 100 are compressed by the same amount in the height direction.

  The gasket 1 is provided with an arcuate constricted portion 3 formed of a concave curve on a side portion facing the groove side surface 43. That is, the width of the side portion of the gasket 1 is configured to gradually decrease from both end portions in the height direction to the center portion. By providing the constricted portion 3 in this way, the cross-sectional shape of the gasket 1 when compressed can be a substantially rectangular shape close to the cross-sectional shape of the groove 41. As a result, the overhang of the gasket side surface in the direction of the groove side surface 43 due to compressive deformation is eliminated, so that the filling rate to the groove 41 at the time of sealing is increased, the groove space is effectively used, and the seal surface is enlarged. An increase in the reaction force of the gasket 1 due to is suppressed.

<Sealing structure>
With reference to FIG.2 and FIG.3, the sealing structure which concerns on a present Example is demonstrated. The sealing structure according to the present embodiment is a structure in which a gap 6 between two members, that is, one member 4 and the other member 5 is sealed by the gasket 1. Both or either of the two members is a cast product, and the surface to which the gasket 1 is in close contact is finished by adjusting dimensions and flatness by cutting. The one member 4 and the other member 5 are assembled and fixed to each other by means not shown (for example, known means such as fitting, fastening with screws, adhesion, etc.). In addition, the arrow in a figure has shown the application pressure direction of the sealing fluid which acts on the gasket 1 from the sealing object area | region.

  The gasket 1 according to the present embodiment seals a gap between planar opposing faces as shown in FIG. 2 and seals a gap between cylindrical opposing faces as shown in FIG. There is. The overall shape of the gasket 1 varies depending on the configuration of the mating member (two members). For example, in the case of the sealing structure shown in FIG. 2, the planar shape of the gasket 1 (the shape seen in the vertical direction in each drawing) is various, such as a circle or a polygon, depending on the target product to which the gasket is applied. Generally, it has an endless shape having no end. Moreover, in the case of the sealing structure shown in FIG. 3, the gasket 1 is comprised in ring shape.

  The sealing structure shown in FIG. 2 will be described. In this sealing structure, the two members have planar opposing surfaces. One of the two members 4 is provided with a groove 41 for mounting the gasket 1 on a surface 40 facing the other member 5. The gasket 1 is attached to the groove 41 and is compressed and deformed so as to be crushed between the groove bottom surface 42 and the opposing surface 50 of the other member 5 to seal the gap 6 between the two members. In FIG. 2, the gasket 1 is shown in a state before being compressed by two members. Actually, as shown in FIG. 5, the gap 6 becomes narrower than the illustrated state, and the gasket 1 is compressed in the opposing direction of the two members by the groove bottom surface 42 and the opposing surface 50.

  The sealing structure shown in FIG. 3 will be described. In this sealing structure, the two members have cylindrical surfaces facing each other. Of these two members, for example, one member 4 is a shaft, and the other member 5 is a housing having a shaft hole into which the shaft is inserted. An annular groove 41 for mounting the gasket 1 is provided on the opposing surface (outer peripheral surface) 40 of one member 4. The gasket 1 is mounted in the groove 41, and is compressed and deformed so as to be crushed in the radial direction between the groove bottom surface 42 and the opposing surface (shaft hole inner peripheral surface) 50 of the other member 5, and the gap 6 between the two members Is sealed. FIG. 3 also shows the gasket 1 in a state before being compressed by the two members, as in FIG. Actually, as shown in FIG. 5, the gap 6 becomes narrower than the illustrated state, and the gasket 1 is compressed in the opposing direction of the two members by the groove bottom surface 42 and the opposing surface 50.

<Dimension setting of gasket>
Each dimension of the cross section of the gasket 1 which concerns on a present Example is set as follows.

As shown in FIG. 1, the product height h0 of the gasket 1 is set to be equivalent to that of the conventional gasket 100 having a substantially circular cross section. Therefore, the gasket 1 of the present embodiment is compressed with a crushing amount equivalent to that of the conventional gasket 100, and the contact width of the sealing surface is larger than that of the gasket 100 by the amount that the curvature of the arc portion 2 is smaller than that of the conventional gasket 100. Greatly increased. Here, as shown in FIG. 4, the crushing amount refers to the product height h0 of the gasket 1 before compression by two members and the distance from the groove bottom surface 42 to the opposing surface 50 in the height direction (the gasket after compression). 1 product height). Further, as shown in FIG. 5, the crushing rate is obtained by dividing the crushing amount by the product height h0, that is, the difference between the product height h0 and the product height h0 ′ at the time of compression (sealing). The one divided by h0.
Crushing rate = (h0−h0 ′) / h0

  6 and 7 show verification results of performance comparison between the gasket according to the present embodiment and the conventional O-ring. In this verification, the gasket for flat surface fixing shown in FIG. 2 is made of a rubber material corresponding to a hardness of 70 degrees as a gasket according to this example, and has an inner diameter of 21.8 mm, h0 of 2.4 mm, and d0 of 2.4 mm. Gasket shape B was used. Further, as a conventional O-ring, a plane fixing O-ring having the same rubber material as the gasket shape B and having the same product width and inner diameter and having a perfect cross-sectional shape was used. The seal contact width, reaction force per unit length, and maximum surface pressure when these gaskets were compressed at a crushing rate of 8% and 25% were calculated from FEM analysis.

  As shown in FIGS. 6 and 7, the gasket shape B according to the present example has a larger contact width on the seal surface while the reaction force and surface pressure are substantially the same as those of a conventional O-ring. Therefore, in sealing the gap between two members having a concave portion formed on the contact surface, it is possible to cover and seal a larger concave portion than the O-ring.

  8-10 has shown the analysis result at the time of changing each dimension of the cross-sectional shape of the gasket which concerns on a present Example.

  As shown in FIG. 8, it can be seen that the contact width of the seal surface is increased by increasing the curvature radius ra. The gasket used in this analysis is made of a rubber material having a hardness of 70 degrees, the crushing rate is 8%, and the friction coefficient is 0.3.

  However, the curvature radius ra is defined in relation to the product width d0, and is preferably set to 0.75 to 2.5 times the product width d0. If it exceeds 2.5 times, the reaction force becomes too large with respect to the predetermined amount of squashing. When the reaction force increases, not only does the deformation stress on the member increase and the member is damaged, but also when the shaft with the gasket attached is inserted into the shaft hole in the cylindrical surface fixing seal application as shown in FIG. There is a concern that the resistance will increase.

  As shown in FIG. 9, it can be seen that the reaction force of the gasket is reduced by reducing the product core width d1, which is the narrowest section width in the constricted portion. The gasket used in this analysis is made of a rubber material having a hardness of 70 degrees, the crushing rate is 8%, and the friction coefficient is 0.3.

  Note that the product core width d1 is desirably set to be larger than 0.4 times the product width d0 in order to suppress buckling or collapse of the gasket 1 which is concerned by providing the constricted portion 3.

  As shown in FIG. 10, in the gasket G (d0 / d1 is 0.4) with a product core width d1 of 0.6 mm, the shaft on which the gasket is mounted in the sealing structure shown in FIG. 3 is inserted into the shaft hole of the housing. When it was done, the gasket collapsed. On the other hand, such a collapse did not occur in the gasket B in which the product core width d1 was 1.6 mm. The gasket used in this analysis is made of a rubber material having a hardness of 70 degrees, the crushing rate is 16%, and the friction coefficient is 0.3.

  The contact width of the sealing surface increases as the product width d0 is increased, and the sealing performance for a cast hole having a larger opening is improved. However, buckling during compression, collapse and reaction force during insertion are reduced. In order to suppress it, the aspect ratio of the gasket shape (product height h0 / product width d0) is preferably 0.8 to 2.0. If it is less than 0.8, the reaction force becomes large in the same seal contact width, and if it exceeds 2.0, it tends to buckle when crushing. On the other hand, by setting it to 0.8 to 2.0, it is possible to expect not only the suppression of buckling during compression and the collapse during insertion but also the reduction of the reaction force during sealing.

<Excellent points of this embodiment>
According to the present embodiment, a seal contact width larger than that of the O-ring 100 having the same product width (product height) can be obtained with the same crushing amount. Thereby, the influence on the sealing performance by the condition of the contact surface of the mating member is reduced. That is, even when the concave portion 51 is formed on the groove bottom surface 42 or the other member surface 50, the expanded sealing surface covers the concave portion 51, thereby suppressing leakage of a sealing fluid or the like through the concave portion 51. can do.

  Further, according to the present embodiment, the constricted portion 3 is provided on the side portion facing the groove side surface 43 of the gasket 1, so that the filling rate of the groove 41 during sealing is increased and the groove space is effectively used. At the same time, an increase in the reaction force of the gasket 1 due to an increase in the contact width of the seal surface is suppressed. In particular, the reduction of the reaction force of the gasket 1 is particularly suitable when both or one of the two members is a resin member that easily deforms compared to a metal member.

  In addition, even when the recessed part is not formed in the surface of 2 members, it can apply as a conventional gasket.

  When the aspect ratio (product height h0 / product width d0) of the gasket 1 according to the present embodiment is 1.0, it can be applied to a mounting groove shape of an O-ring standardized by normal JIS. Therefore, no special groove shape is required.

  According to the present embodiment, it is possible to eliminate problems caused by adopting a cast product. Therefore, it is possible to actively adopt cast products, which can contribute to a reduction in the number of processes, non-conforming products, management work, and the like.

1 Gasket 2 Arc-shaped part (seal surface)
3 Constricted portion 4 One member 40 Surface 41 Groove 42 Groove bottom surface 43 Groove side surface 5 Other member 50 Surface 51 Concave portion 6 Gap

Claims (2)

It is mounted in a groove provided in one of the two members and is compressed between the two members, thereby forming a sealing surface that closely contacts the groove bottom surface of the groove and the surface of the other member. A gasket for sealing a gap between members,
In the cross section obtained by cutting the gasket along the height direction and the width direction with the compression direction as the height direction and the direction in which both side surfaces of the groove face each other as the width direction, the region forming the seal surface in the outline of the cross section Is an arc-shaped portion configured with a curved curve toward the groove bottom surface and the surface of the other member, respectively, in a state before the gasket is compressed between the two members.
In the gasket having an arcuate constricted portion formed of a concave curve in a region facing the side surface of the groove,
The convex arcuate portion is constituted by a curve having a curvature smaller than a curvature of a cross section of a gasket having a circular section having substantially the same height. Two members, both or one of which is a casting,
The gasket according to claim 1, which seals a gap between the two members;
A sealing structure comprising:

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