JP4130862B2 - Seal structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a seal structure of two members, and more particularly to a seal structure of an engine cylinder head and a rocker cover.
[0002]
[Related background]
In the engine, a valve mechanism is provided on the cylinder head, and a rocker cover is placed on the cylinder head in order to protect it.
By the way, the lubricating oil is supplied to the valve operating mechanism for the purpose of lubricating each part such as the camshaft, and the rocker cover scatters the lubricating oil around by the high speed operation of each part such as the camshaft. It also has a function to prevent this.
[0003]
Furthermore, blowby gas leaking from the gap between the cylinder and the piston is generally guided into the space inside the rocker cover (hereinafter referred to as the rocker chamber). The rocker cover leaks this blowby gas to the surroundings. It also has a role to prevent it.
For this reason, it is necessary to completely prevent leakage of lubricating oil and blow-by gas to the outside of the engine, and a seal member is interposed between the cylinder head and the rocker cover in order to seal the rocker chamber. I have to. For example, a groove having a rectangular cross section is formed in the peripheral flange portion of the rocker cover facing the cylinder head, and an annular seal member (gasket) having elasticity molded in advance so as to fit the groove is fitted into the groove. A method is known in which a cover is pressed against a cylinder head while being fastened with a fastening member so that the seal member is compressed and brought into close contact with the cylinder head for sealing.
[0004]
Furthermore, Japanese Utility Model Laid-Open No. 64-14960 discloses a seal structure in which the cross-sectional shape of the groove is asymmetrical and the compressive stress is concentrated on one side of the seal member to improve the seal performance.
However, in such a sealing structure in which a projection of a sealing member molded in advance in a deep groove having a rectangular cross section is fitted and compressed and deformed on two asymmetric steeply inclined surfaces to obtain a sealing property, the groove and the sealing member In such a case, there is a possibility that a gap is generated between the rocker cover and the seal member, and the rocker chamber cannot be maintained in a sealed state. It is not preferable because there is a risk of breaking. Furthermore, in order to improve the sealing performance, planar pressing that pushes the sealing member in a perpendicular direction on a flat surface is preferable. However, in the above structure, the pressing force may decrease and the sealing performance may deteriorate.
[0005]
Therefore, the peripheral flange portion of the rocker cover is a flat surface, and a coating hardening molding gasket (CIPG; Cured In-Place Gasket) is applied and cured on the flat surface, and the rocker cover is pressed while being fastened to the cylinder head with a fastening member. Thus, a method of bringing the coating / curing gasket into close contact with the upper surface of the cylinder head by compression has been put into practical use.
[0006]
[Problems to be solved by the invention]
By the way, in the method using the coating and hardening formed gasket with the peripheral flange portion of the rocker cover as a flat surface, no gap is generated between the rocker cover or the cylinder head and the coating and hardening formed gasket. If it is not securely bonded to at least one of the cylinder heads, there is a problem that the peripheral flange portion is displaced from an appropriate position due to a change in pressure in the rocker chamber. If the coating / curing gasket is displaced in this manner, the airtightness of the rocker chamber is impaired, and lubricating oil and blow-by gas leak to the outside, which is not preferable.
[0007]
Therefore, in order to prevent this, primer paint is applied (primer treatment) to either the peripheral flange portion of the rocker cover or the cylinder head facing the rocker cover, thereby ensuring that the coating and curing gasket is applied to the rocker cover or cylinder head. However, application of primer paint leads to cost increase due to increase in material cost and work man-hours, and adhesiveness depends on the application form and includes quality instability factors. It is not preferable.
[0008]
The present invention has been made to solve such problems, and an object of the present invention is to provide an inexpensive and highly reliable seal structure.
[0009]
[Means for Solving the Problems]
To achieve the above object, the invention of claim 1, a groove is formed in opposing surfaces of the Uchi該rocker cover of the opposing surfaces of the cylinder head and the rocker cover is fastened via a sealing member having elasticity, in sealing structure sealing member fastening the said cylinder head and rocker cover while being maintained in the interior of the groove, the rocker cover the groove has a triangular cross-section, the deepest in the direction along the above facing surfaces The inward side is biased. That is, the groove has a “he” shape.
[0010]
Therefore, by attaching an elastic seal member so as to be along the deepest part of the groove having a triangular cross section formed on the opposite surface of the rocker cover , the seal member can be satisfactorily held in the groove, and the groove A rocker cover seal member in which a groove with a gentle slope can be formed on the other side of the cross-sectional triangle by biasing the deepest part of the cross-sectional triangle toward the inner side of one rocker cover in a direction along the opposing surface. By increasing the effective pressing surface against the above, it is possible to obtain a pressing force substantially the same as the flat pressing with the highest pressing force, and a high sealing performance can be obtained.
[0011]
Furthermore, the seal member generates a pressing force with an inward force toward the deepest portion due to the action of the surface having the gentle slope due to its elasticity, and the inward force in the pressing force is the rocker that is biased to the deepest portion. Since the inward inclination of the cover is reliably received by a steep surface, the seal member is corrected and held so as not to be displaced in the groove.
Further, the pressing force accompanied with the inward force has an action of pushing back the penetration of the leakage from the deepest portion into the seal portion surface. That is, when pressure from the deepest part is applied, the seal member deforms between the cylinder head and the rocker cover and functions like a rust, further improving the sealing performance , despite the increased pressure in the rocker chamber. Leakage of lubricating oil and blow-by gas is reliably prevented.
[0012]
As a result, it is possible to realize a low-cost and highly reliable seal structure without applying a primer treatment, although it is a simple structure .
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
Referring to FIG. 1, an engine 1 to which a seal structure according to the present invention is applied is shown.
The engine 1 is, for example, an OHC (overhead cam) type gasoline engine, and a cylinder head 4 is mounted and fastened to the cylinder block 2. The cylinder head 4 includes an ignition plug, an intake / exhaust valve, A valve operating mechanism such as a rocker arm and a camshaft is provided. As shown in the figure, a rocker cover 6 is placed on the cylinder head 4 to protect the spark plug and the valve mechanism, and the rocker cover 6 is fastened to the cylinder head 4 with bolts or the like. ing. The rocker cover 6 is made of, for example, a moldable aluminum cast alloy.
[0016]
By the way, lubricating oil is supplied to the valve operating mechanism through an oil passage provided in the engine 1, and the lubricating oil is scattered around by high-speed rotation of the camshaft. Accordingly, the rocker cover 6 also has a function of preventing the scattered lubricating oil from leaking to the outside. Further, the space inside the rocker cover 6, that is, the rocker chamber 12 is configured such that blowby gas leaking from the gap between the cylinder and the piston is temporarily stored before being sent to the intake system. Has a role not to leak the blow-by gas to the outside.
[0017]
For this reason, the rocker chamber 12 needs to be sealed, and a gasket 10 (seal member) is interposed between the cylinder head 4 and the rocker cover 6. Thereby, the clearance gap between the cylinder head 4 and the rocker cover 6 is sealed, and the airtightness of the rocker chamber 12 is ensured. Hereinafter, the seal structure between the cylinder head 4 and the rocker cover 6 according to the present invention will be described in detail.
[0018]
Referring to FIG. 2, a cross section taken along line AA in FIG. 1 is shown. As shown in the figure, a flange 7 is formed on the periphery of the rocker cover 6 facing the upper surface of the cylinder head 4 so as to extend outward. A surface 7a of the flange 7 facing the upper surface of the cylinder head 4 is formed on the surface 7a. A groove 8 having a triangular cross section is formed over the entire circumference of the flange 7.
[0019]
As shown in the figure, the depth a of the groove 8 is not so deep. For example, the ratio (a / b) to the width b of the groove 8 is about 0.1 to 0.17.
The deepest portion 8a of the groove 8 is biased toward the inner side of the rocker cover 6, that is, the rocker chamber 12 side. In other words, the groove 8 is formed in a “h” shape with the deepest portion 8 a positioned on the inner side of the rocker cover 6.
[0020]
The gasket 10 is interposed between the flange 7 and the upper surface of the cylinder head 4 so as to be along the deepest portion 8 a of the groove 8.
Here, the gasket 10 is, for example, the above-described coating-curing gasket (CIPG or the like), that is, a gel-like shape having adhesiveness when applied, and changes to an elastic rubber shape after a certain amount of time in the air. It is a gasket with properties.
[0021]
Therefore, in practice, the gasket 10 is previously applied to the rocker cover 6 in advance so that the material cross-sectional area is constant at a predetermined value along the deepest portion 8a of the groove 8 of the flange 7. When the rubber shape is obtained, the rocker cover 6 is placed on the upper surface of the cylinder head 4. As a result, the gasket 10 is interposed between the flange 7 and the upper surface of the cylinder head 4 as illustrated.
[0022]
By the way, as shown in the figure, the flange 7 is provided with a plurality of protrusions 9 having a predetermined height at predetermined intervals so as not to interfere with the gasket 10, and the protrusions 9 are formed by the rocker cover 6. When placed on the upper surface of the cylinder head 4, the upper surface of the cylinder head 4 is brought into contact with the upper surface. Here, the predetermined height is set to a value sufficiently smaller than the material diameter of the gasket 10. Thereby, even if the rocker cover 6 is fastened to the cylinder head 4 with a bolt or the like, the gasket 10 is prevented from being excessively compressed and causing a material crack or breakage.
[0023]
As shown in FIG. 4, the protrusion 9 may not be provided, and the rocker cover 6 and the cylinder head 4 may be in contact with the outer peripheral side plane and the inner peripheral side plane of the groove 8.
Hereinafter, the effect of the seal structure configured as described above will be described.
As described above, the gasket 10 is interposed between the rocker cover 6 and the cylinder head 4 along the deepest part 8 a of the groove 8 of the flange 7 formed in the rocker cover 6.
[0024]
That is, on the rocker cover 6 side, the gasket 10 is in contact with the steep slope 8b extending from the deepest portion 8a to the inside of the rocker cover 6, that is, the rocker chamber 12 side, and the gentle slope 8c extending to the outside of the rocker cover 6. .
Thus, when the gasket 10 is in contact with the steep slope 8b and the gentle slope 8c, the hardened gasket 10 is reliably blocked by the steep slope 8b although it is pushed to the rocker chamber 12 side by the inward force generated by the gentle slope 8c. , It cannot move to the rocker chamber 12 side, but is corrected to the position of the deepest portion 8a and stably held. Even when the pressure in the rocker chamber 12 becomes smaller than the atmospheric pressure and the gasket 10 is pushed to the rocker chamber 12 side by the atmospheric pressure, the gasket 10 is well held at the deepest portion 8a position of the groove 8 and the rocker It is preferably prevented from falling off to the chamber 12 side.
[0025]
Further, since the gasket 10 is in contact with the gentle slope 8c, the pressing surface on which the flange 7 presses the gasket 10 is sufficiently secured as in the case where the flange 7 is a flat surface without the groove 8. That is, when the rocker cover 6 is fastened to the cylinder head 4 with a bolt or the like, the flange 7 presses the gasket 10, and thus an effective pressing surface of the flange 7 against the gasket 10 is sufficiently secured. As a result, a pressing force substantially the same as the flat pressing with the highest pressing force is obtained, the gasket 10 is compressed well, and a sufficient pressing force is generated by the elastic force of the gasket 10, and between the rocker cover 6 and the gasket 10 and High sealing performance is obtained between the cylinder head 4 and the gasket 10.
[0026]
FIG. 3 shows a situation where the pressure in the rocker chamber 12 is higher than the atmospheric pressure and the gasket 10 is pushed outward from the rocker cover 6.
As shown in the figure, when the pressure in the rocker chamber 12 becomes higher than the atmospheric pressure, the gasket 10 tries to move to the outside of the rocker cover 6 along the gentle slope 8c. When the gasket 10 is peeled off, the gasket 10 moves slightly toward the outside of the rocker cover 6 along the gentle slope 8c.
[0027]
However, at this time, as shown in the figure, the gap between the flange 7 and the cylinder head 4 becomes smaller toward the outer side of the rocker cover 6 due to the presence of the gentle slope 8c, and the gasket 10 is placed on the upper surface of the cylinder head 4. It extends in the direction along which the width expands. The deformation of the gasket 10 so that the width of the gasket 10 increases in this way means that the effective pressing surface with which the flange 7 presses the gasket 10 increases, and the elasticity of the gasket 10 causes the flange 7 of the gasket 10 and the cylinder head 4 to This means that the crimping force of is increased. That is, when the pressure in the rocker chamber 12 becomes higher than the atmospheric pressure and the gasket 10 is pushed to the outer side of the rocker cover 6, the gasket 10 functions like a wedge between the flange 7 and the upper surface of the cylinder head 4. This serves to push back the penetration of the lubricating oil or blow-by gas into the seal portion, thereby improving the sealing performance. This reliably prevents leakage of the lubricating oil and blow-by gas to the outside regardless of an increase in the pressure in the rocker chamber 12.
[0028]
As described above, in the seal structure of the present invention, the deepest portion 8 a is positioned on the inner side of the rocker cover 6, and the groove 8 having a triangular cross section formed in a “he” shape is formed over the entire circumference of the flange 7. Thus, it is possible to ensure a high sealing performance at all times and to hold the gasket 10 in the groove 8 satisfactorily without being displaced regardless of the pressure change in the rocker chamber. Therefore, according to the present invention, a low-cost and highly reliable seal structure between the rocker cover 6 and the cylinder head 4 can be obtained without applying a primer treatment.
[0029]
That is, by applying the seal structure according to the present invention between the rocker cover and the cylinder head of the engine, providing a groove on the rocker cover side, and biasing the deepest part of the groove having a triangular cross section toward the inside of the rocker cover, The seal member can be pressed well at the other gently inclined portion of the cross-sectional triangle of the groove to ensure the sealing performance, and the inward force during the pressing force is reliably received on the steeply inclined surface so that the seal member can be It can be held stably between the cylinder heads, and when the pressure in the rocker chamber rises and the seal member tries to shift to the outside of the rocker cover where the groove is slanted, a pressure is applied to push the seal member back to the rocker chamber side. It is possible to further improve the sealing performance and prevent leakage of lubricating oil and blow-by gas to the outside despite the pressure rise in the rocker chamber. It is possible to really prevent. This makes it possible to obtain a rocker cover sealing structure that is inexpensive and highly reliable.
[0030]
【The invention's effect】
As described above in detail, according to the seal structure of claim 1 of the present invention, the facing surface of the Uchi該rocker cover of the opposing surfaces of the cylinder head and the rocker cover is fastened via a sealing member having elasticity Since the groove with the “H” shape is formed with a triangular cross section and the deepest part is biased toward the inner side of one of the rocker covers in the direction along the opposite surface, the groove is inclined to the other side of the cross sectional triangle of the groove. Can be formed, and by increasing the effective pressing surface against the seal member of the rocker cover in which the groove is formed, it is possible to obtain almost the same pressing force as the flat pressing with the highest pressing force, and high sealing performance In addition, the inward force during the pressing force can be reliably received on the deepest part and the steeply inclined surface on the inner side of the rocker cover that is biased, and the seal member is corrected so that it does not slip into the groove do it It is possible to equity. Also, when the pressure from the deepest part rises, the seal member deforms between the cylinder head and the rocker cover , functions like a wedge and works to push back the penetration of the leaked part from the deepest part side. Thus, extremely high sealing performance can be ensured. Thereby, although it is a simple structure, it can implement | achieve cheap and reliable sealing structure, without performing a primer process.
[Brief description of the drawings]
FIG. 1 is a view showing an engine to which a seal structure according to the present invention is applied.
2 is a cross-sectional view taken along the line AA in FIG. 1, and is a view showing details of a seal structure according to the present invention.
FIG. 3 is a diagram showing a situation when a gasket is pushed outward from the rocker cover due to an increase in pressure in the rocker chamber.
4 is a diagram showing details of a seal structure when no protrusion is provided with respect to FIG. 2. FIG.
[Explanation of symbols]
1 Engine 4 Cylinder head 6 Rocker cover 8 Groove 8a Deepest part 8b Steep slope 8c Slow slope 10 Gasket (seal member)

Claims (1)

Said cylinder in a state in which a groove is formed in opposing surfaces of the Uchi該rocker cover of the opposing surfaces of the cylinder head and the rocker cover, the sealing member is maintained in the interior of the groove which is fastened via a sealing member having elasticity A seal structure for fastening the head and the rocker cover ;
The groove structure has a triangular cross section, and the deepest portion is biased inward of the rocker cover in a direction along the facing surface.

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