JPH08285084A - Packing - Google Patents

Abstract

PURPOSE: To provide packing having a large restoring stroke and sufficient durability. CONSTITUTION: Packing 1 is formed of a body part 2 fitted into a groove 7 formed at a cylinder head cover 5, and a leg part 3 extended in bifurcated shape from the cylinder head cover 5 side of the body part 2. A space 4 is formed at the cylinder head cover 5 side center part of the leg part 3 extended in bifurcated shape, and the length of the body part 2 is made shorter than the depth of the groove 7 formed at the cylinder head cover 5. At the time of clamping a cylinder head 6 and the cylinder head cover 5, the leg part 3 is first flexure-deformed, then the body part 2 is compression-deformed, and finally the leg part 3 is compression-deformed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packing for sealing between two members to be joined.

[0002]

2. Description of the Related Art While a cylinder head and a head cover of an internal combustion engine have a scattering of oil inside and a high sealing performance is required, a thin portion is inevitably required to prevent deformation. In connection with the requirement that the joint cannot be tightened with a large force, an elastic packing is provided, and the sealing force is secured by the restoring force of the packing. Therefore, the packing used as described above is required to have a large restoring stroke and a long restoring force. Therefore, conventionally, various packings have been developed and, for example, according to Japanese Utility Model Laid-Open No. 2-134360, a main body portion fitted in a fitting groove and two protrusions for elastically engaging the overlapping surface are provided. A packing having a groove for absorbing deformation of the ridge on both sides of the ridge is disclosed.

[0003]

However, in the packing of the above publication, in order to prevent excessive deformation of the two protrusions, the reaction force of tightening is received by the central body portion. Therefore, the variation in the tightening amount with respect to the variation in the reaction force may increase, and the tightening force at the time of assembly may vary. Also, in order to increase the compression allowance, it is necessary to increase the crushing amount of the main body part, which increases the tightening force and causes the flattening of the seal washer used when tightening the cylinder head cover and cylinder head with bolts. However, there is a problem that the tightening force of the member is reduced. In view of the above problems, it is an object of the present invention to provide a packing that is easy to perform tightening management, has a large restoring stroke, and can maintain a long restoring force.

[0004]

According to the present invention, a main body portion fitted into a groove formed in one member of two members to be fastened and a bending margin space from the other member side of the main body portion. A packing composed of a leg portion extending in a forked shape sandwiching the leg portion, wherein a length in a tightening direction of the main body portion is set to be larger than a depth of the groove to be fitted, and a bending deformation ratio of the leg portion with respect to a tightening load. Is set to be larger than the compressive deformation rate of the main body portion with respect to the tightening load, and when the tightening load is applied to the two members, the leg portion is bent and deformed by the tightening load applied to the main body portion until there is no bending allowance space. After that, the packing is characterized in that only the main body portion is compressed and deformed, and then the leg portion is compressed and deformed after the one member is brought into contact with the leg portion.

[0005]

In the present invention, the deformation ratio of the leg portion with respect to the tightening load is set to be higher than the compressive deformation ratio of the main body portion with respect to the tightening load. Therefore, when the two members are fastened, It is greatly bent and deformed. That is, when the main body comes into contact with the bottom of the groove during tightening,
The leg portion is bent and deformed by the compressive force acting through the main body portion until there is no bending allowance space. Then, after that, since there is no bending deformation, only the main body portion is compressed and deformed, and after the leg portion comes into contact with the one member, only the leg portion is compressed and deformed, whereby the tightening load changes in three stages.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a cross-sectional view of a packing according to the present invention used between a cylinder head and a cylinder head cover of an engine, showing a state before tightening. FIG.
In FIG. 1, 1 is the whole packing, 2 is its body part, 3 is a leg part, and 4 is a bending margin space formed in the lower central part of the leg part 3. On the other hand, 5 is a cylinder head cover, and 6 is a cylinder head. A groove 7 is provided in the cylinder head cover 5, and the main body 2 of the packing 1 is fitted in the groove 7. Further, although not shown, the cylinder head cover 5 and the cylinder head 6 are bolted via a seal washer having elasticity, so that a tightening force acts on the packing.
Here, the depth D of the groove 7 is smaller than the length L in the tightening direction of the body portion 2 of the packing 1 before the tightening force is applied. Further, the bending deformation ratio of the leg portion 3 in the tightening direction with respect to the tightening load is set to be larger than the compressive deformation ratio of the main body portion 2 in the tightening direction with respect to the tightening load.

FIG. 2 shows the change from the state before tightening to the end of tightening. Further, FIG. 3 shows the relationship between the tightening amount and the tightening force, that is, the reaction force of the packing 1, between them. FIG. 2A shows a state before tightening, and in this state, a bending allowance space 4 having a depth h1 exists. Then, when the tightening is started, the bending deformation rate in the tightening direction is set to be higher than the compressive deformation rate in the tightening direction of the main body portion 2.
Bends and expands to the left and right, the bending allowance space 4 gradually decreases, and finally disappears, and the center 3a of the leg portion 3 abuts on the surface of the cylinder head 4, resulting in the state of FIG. Therefore, the amount of tightening between (A) and (B) of FIG. 2 is equal to the depth h1 of the bending allowance space 4, and the reaction force therebetween increases slightly from point A to point B in FIG. In this range, the tightening amount (restoring stroke) can be taken without increasing the reaction force.

When the tightening is further performed from the state of FIG. 2B, the bending allowance space 4 disappears, so that bending deformation no longer occurs and only the main body 2 of the packing 1 is compressed, and eventually. As shown in FIG. 2C, the flat portion 5a of the cylinder head cover 5 comes into contact with the upper surface 3b of the leg portion 3. During this time, the main body 2 changes from the value close to the original length L to the groove depth D, but the tightening amount h2 between (B) and (C) in FIG. 2 is substantially equal to L-D. And the reaction force between them is from point B to point C in FIG.
It increases more than the rate of increase from point to point B.

When the state shown in FIG. 2C is further tightened, the flat portion 5a of the cylinder head cover 5 comes into contact with the upper surface of the leg portion 3 and the leg portion 3 starts to be compressed. Then, the reaction force further increases from point C in FIG. The increase in the reaction force with respect to the tightening amount increases from point C onward, but this is due to the large pressure receiving area of the legs. And
Tightening is completed at point D where the reaction force reaches a predetermined value. In this way, by controlling the tightening force at point D where the increase in the reaction force with respect to the tightening amount is large, even if the tightening force varies, the error in the tightening amount can be reduced. 2D shows the state in which the tightening is completed as described above, and the tightening amount h3 between (C) and (D) in FIG. 2 is the opposite from the point C to the point D in FIG. Corresponding to increased power.

At point D where the tightening reaction force is large, a large compressive stress is generated in the seal washer, and the seal washer may creep due to the high temperature environment during actual operation. However, due to this creep, the compression amount of the packing decreases. The amount of tightening of the packing is in the range from point A to point B or from point B to point C, and the compressive stress acting on the seal washer sharply decreases. Due to the reduction of the compressive stress, the seal washer does not creep any more, and thus it is possible to maintain a stable sealed state for a long period of time. Further, since the leg portion after tightening is in close contact with the cylinder head over a wide range, oil leakage can be further reduced.

[0011]

According to the present invention, the leg is returned from the bent state, the body is returned from the compressed state, and the leg is returned from the compressed state. 3 with return
Since a large amount of restoration can be used, the restoration stroke can be made large and the sealing performance can be maintained for a long period of time. Further, by controlling the tightening force in the compressed portion of the leg portion, it is possible to reduce variations during assembly.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a diagram showing a change in the shape of packing with a change in a tightening amount.

FIG. 3 is a diagram showing a relationship between a tightening amount and a reaction force of a packing.

[Explanation of symbols]

 1 ... Packing 2 ... Body part 3 ... Leg part 4 ... Bending allowance 5 ... Head cover 6 ... Cylinder head 7 ... Groove

Claims (1)

[Claims] 1. A body portion fitted into a groove formed in one member of two members to be fastened, and a leg portion extending in a bifurcated shape from the other member side of the body portion with a bending margin space therebetween. The length of the main body in the tightening direction is set to be larger than the depth of the groove to be fitted, and the bending deformation rate of the legs with respect to the tightening load is the compression deformation of the main body with respect to the tightening load. When the tightening load is applied to the two members, the leg part is bent and deformed until the bending allowance space disappears, and then only the main body part is compressed and deformed. Then, the packing is characterized in that the leg portion is compressed and deformed after the one member contacts the leg portion.