JP2001141063A - Cylinder head gasket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylinder head gasket that can completely remove dead volume and machining of a projection on the upper part of a cylinder liner is not required. SOLUTION: A fire ring 7 is mounted to the inner peripheral side of a metallic bore grommet 3 mounted on a metallic core pleat 9a. Both surfaces of a metal plate 7a of the fire ring 7 are coated with compound layers 7c containing compressive inorganic fiber except for asbestos, compressive organic fiber, inorganic filler, and rubber. Thickness t7a of the metal plate 7a is thinner than the thickness of the bore grommet 3 at a fastening time, and total thickness t7 of the fire ring 7 before the fastening is thicker than the thickness of the bore grommet 3 at the fastening time. When fastening, the compound layers 7c are compressed, both surfaces of the fire ring 7 closely adhere to the lower surface of a cylinder head and the upper surface of the cylinder liner to completely remove the dead volume.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cylinder head gasket mounted between a cylinder head and a cylinder block of an engine.

[0002]

FIG. 1 shows an example of the structure of a cylinder in a conventional large diesel engine. In order to reduce the load acting on the main body 1a of a cylinder liner 1, a bore grommet 3 of a cylinder head gasket 2 is shown. Is positioned outside the inner circumference of the liner 1, so that the gas seal portion of the cylinder head gasket 2 is located on the outer periphery of the upper end of the liner 1.
It is shifted to the side to reduce bore deformation. In order to prevent a large so-called dead volume A in which unburned gas is accumulated between the upper surface of the liner 1, the lower surface of the cylinder head 4 and the inner periphery of the bore grommet 3, the liner 1
(A flame prevention zone) 1c is provided at the upper end of the slab. Reference numeral 6 denotes a cylinder block.

FIG. 2 shows another example of the structure of a cylinder in a conventional large diesel engine. In order to reduce the dead volume A, a protrusion 1c is not provided at the upper end of the liner 1 and a cylinder head is provided. Gasket 2
The inner circumference of the bore grommet 3 part is set close to the inner circumference of the liner 1.

FIG. 3 shows still another example of the structure of a cylinder in a conventional large diesel engine. In order to reduce the dead volume A, the protrusion 1c is not provided at the upper end of the liner 1 and metal is used. A fire ring 7 composed of only a plate is provided on the inner peripheral side of the bore grommet 3 of the cylinder head gasket 2.

[0005]

However, in the conventional cylinder structure shown in FIG. 1, it is necessary to (a) process the projection 1c on the liner 1, and this processing is performed when the cylinder head gasket 2 is tightened. Since it is necessary to prevent the projection 1c from coming into contact with the cylinder head 4 and to prevent the distance from the head 6 from becoming large, high processing accuracy is required, so that the processing cost of the liner 1 increases. B) Even if the above processing is performed, the dead volume A cannot be completely removed, and unburned gas accumulates in the dead volume A, and there is a problem that the HC concentration in the exhaust gas is increased.

Further, in the conventional cylinder structure shown in FIG. 2, since it is not necessary to process the projections 1c on the liner 1, the processing cost of the liner 1 can be reduced, but (c) it is less than in the case of FIG. However, it is still impossible to completely remove the dead volume A. (d) Liner 1
Crack 8 is likely to occur near the intersection between the main body 1a and the block holding portion 1b, and (e) cylinder bore deformation is liable to occur as shown by the dashed line 1 ', thereby increasing oil consumption and increasing piston performance. There are problems such as easy seizure.

Further, the conventional cylinder structure shown in FIG. 3 does not need to process the projection 1c on the liner 1, so that the processing cost of the liner 1 can be reduced. In addition, bore grommet 3
Is located outside the inner circumference of the liner 1, so that in an appropriate assembly state, deformation of the cylinder bore, cracking of the liner 1, and the like can be prevented. However, (f) Since the fire ring 7 is made of only metal, a clearance is required between the cylinder head 4 and the cylinder liner 1 and the fire ring 7, and these clearances become dead volumes A. One fire ring 7 has a cylinder head 4 and a cylinder liner 1
Contact, there are problems such as gas leakage, increased bore deformation, and cracking of the liner 1.

[0008] The present invention has been made in view of such conventional circumstances, and one object of the present invention is to completely eliminate dead volume, thereby reducing the concentration of HC in exhaust gas. It is another object of the present invention to provide a cylinder head gasket that can improve fuel efficiency and does not need to process a projection on an upper portion of a cylinder liner.

Another object of the present invention is to provide a cylinder head gasket in which a fire ring portion does not adhere to a cylinder head and a liner portion.

[0010] Still other objects of the present invention will become apparent from the following description.

[0011]

SUMMARY OF THE INVENTION A cylinder head gasket according to the present invention comprises a core plate made of metal, a cylinder hole provided in the core plate, and a bore grommet made of metal mounted on a peripheral portion of the cylinder hole. And a fire ring mounted on the inner peripheral side of the bore grommet, wherein the fire ring is formed of a metal plate and coated on both sides of the metal plate, compressible inorganic fibers other than asbestos, A layer of a compound containing a conductive organic fiber, an inorganic filler and rubber, wherein the thickness of the metal plate of the fire ring is smaller than the thickness of the bore grommet portion when tightened. The total thickness of the fire ring before tightening is greater than the thickness of the bore grommet portion when tightened.

According to the present invention, since the total thickness of the fire ring before tightening is greater than the thickness of the bore grommet portion at the time of tightening, the fire ring is interposed between the cylinder head and the cylinder block and tightened. When fired, the layer of compound of the fire ring is compressed between the cylinder head and the cylinder liner, and both surfaces of the fire ring adhere to the lower surface of the cylinder head and the upper surface of the cylinder liner, respectively. Therefore, the dead volume can be completely removed.

Further, since the compound layer contains a compressible organic fiber, a compressible inorganic fiber and a rubber, it is highly compressible, so that the fire ring conforms well to the lower surface of the cylinder head and the upper surface of the liner.
From this point, the dead volume can be completely removed.

Further, the lower surface of the cylinder head and the upper surface of the cylinder liner come into contact with both surfaces of the fire ring. However, the total thickness of the fire ring before tightening is excessively larger than the thickness of the bore grommet portion when tightened. Unless otherwise mentioned, since the compound layer is highly compressible as described above, the applied stress is small, so that the gas sealing property is not reduced, the cylinder bore deformation is increased, and the liner portion is not cracked.

Further, as described above, since the compound layer has high compressibility, even if the thickness of the bore grommet portion at the time of tightening varies, there is little variation in the load surface pressure of the fire ring portion.

Generally, the temperature of the lower surface of the cylinder head and the upper surface of the liner is about 200 ° C. However, since the compound contains a compressible organic fiber, a compressible inorganic fiber, an inorganic filler and rubber, the compound has a heat resistance of 400 ° C.
Since it can be set to a degree, it has sufficient heat resistance.

The total thickness of the fire ring before tightening is 4 times larger than the thickness of the bore grommet portion when tightened.
The thickness is preferably up to 12%, particularly preferably 5 to 9%. If the total thickness of the fire ring is too small than the thickness at the time of tightening the bore grommet, the surface pressure of the fire ring will be too small and the compound layer will have a large settling, and the fire ring, cylinder head and cylinder liner It is easy for gas to enter between. On the other hand, if the total thickness of the fire ring is too large than the thickness at the time of tightening the bore grommet portion, the compression amount of the fire ring becomes excessive as a whole, and the surface pressure of the fire ring may become excessive. .

Further, if the surface of the compound layer is coated with a layer mainly composed of graphite, adhesion of the upper and lower surfaces of the fire ring to the lower surface of the cylinder head and the upper surface of the cylinder liner can be prevented,
During operation, the fire ring including the compound layer is not deteriorated due to the movement of the lower surface of the head and the upper surface of the liner.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION As a metal plate for a fire ring in a cylinder head gasket of the present invention, for example, a stainless steel plate such as SUS, a steel plate such as SPCC, and the like are preferable.

The compressible inorganic fibers constituting the compound of the fire ring in the cylinder head gasket of the present invention include, for example, glass fiber, ceramic fiber, rock wool, mineral wool, fused quartz fiber, chemically treated high silica fiber, Molten silicate alumina fiber, alumina continuous fiber, stabilized zirconia fiber, boron nitride fiber, alkali titanate fiber, whisker, boron fiber and the like can be used.

Examples of the compressible organic fibers constituting the compound include aramid fibers (aromatic polyamide fibers), polyamide fibers, polyolefin fibers, polyester fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers, and the like. Polyvinyl chloride fiber, polyurea fiber, polyurethane fiber, polyfluorocarbon fiber, phenol fiber, cellulose fiber and the like can be used.

It is preferable that the compressible inorganic fiber and the organic fiber are blended in the compound in an amount of about 30 to 80% by weight.

Since compressible inorganic fibers other than asbestos have poor flexibility, if only inorganic fibers other than asbestos are used as the fibers constituting the compound, the conformability of the fire ring to the cylinder head and the liner is reduced. . On the other hand, since the heat resistance of the organic fiber is poor, if only the organic fiber is used as the fiber constituting the compound, the heat resistance of the fire ring deteriorates. Also, when an organic filler is used as the filler, the heat resistance is reduced. Therefore, if both the compressible inorganic fiber and the compressible organic fiber and the inorganic filler are used, both the conformability and the heat resistance can be satisfied.

Examples of the elastomer constituting the compound include nitrile rubber (NBR), styrene butadiene rubber (SBR), isoprene rubber (IR), chloroprene rubber (CR), butadiene rubber (BR), butyl rubber (IIR), ethylene -Propylene rubber (EP
M), fluoro rubber (FPM), silicone rubber (S
i), chlorosulfonated polyethylene (CSM), ethylene-vinyl acetate rubber (EVA), polyethylene chloride (CP)
E), rubber materials such as butyl chloride rubber (CIR), shrimp chlorohydrin rubber (ECO), and nitrile isoprene rubber (NIR) can be used. Also, other types of elastomers can be used instead of rubber.

Further, as the inorganic filler constituting the compound, for example, clay, talc, barium sulfate,
Sodium bicarbonate, graphite, lead sulfate, tripoliite, wollastonite and the like can be used.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

FIGS. 4 to 6 show an embodiment of the cylinder head gasket 2 according to the present invention, and FIG. 7 shows a state in which this embodiment is interposed between the cylinder head 4 and the cylinder block 6 and tightened. . The cylinder head gasket 2 of the present embodiment includes a gasket main body 9 and a bore grommet 3.
And a fire ring 7. The gasket main body 9 includes a core plate 9a made of a metal plate such as SUS or SPCC, and a surface plate 9 laminated on both sides of the core plate 9a.
b. Each of the surface plates 9b is a metal plate 9c.
Are coated with a thin compound layer 9d containing compressible inorganic fibers other than asbestos, compressible organic fibers, inorganic filler and rubber.

The gasket body 9 has a cylinder hole 1
1, a water hole 12 for passing cooling water, an oil hole 13 for passing lubricating oil, and a bolt hole 14 are provided. In the gasket main body 9, the surface plate layer 9 b is not provided in the peripheral portion of the cylinder hole 11, and the metal bore grommet 3 made of stainless steel such as SUS is provided on both sides of the peripheral portion. It is attached so as to sandwich it.

The fire ring 7 is formed by applying a heat-resistant adhesive 7b to both surfaces of an annular metal plate 7a made of a stainless steel plate such as SUS, a steel plate such as SPCC, etc., and then forming a compound layer 7c having the following composition. After coating on both surfaces of the metal plate 7a and further coating a layer 7d containing graphite as a main component (hereinafter referred to as a graphite layer) 7d on the surface of the compound layer 7c,
Heat treatment is performed at a temperature of 60 ° C. for 30 to 40 minutes. [Compound composition] Glass fiber: 30% by weight Fibrillated aromatic polyamide fiber (Kevlar pulp, manufactured by DuPont): 10% by weight Nitrile rubber (NBR): 16% by weight Rubber chemicals: 4% by weight Inorganic filler ... 40% by weight In the composition of the compound, the glass fiber is a kind of inorganic fiber, and the fibrillated aromatic polyamide fiber is a kind of organic fiber.

The rubber chemicals in the composition of the compound include, for example, vulcanizing agents such as sulfur, zinc oxide, magnesium oxide, peroxide, dinitroribenzene, and the like, thiazole compounds, polyamine compounds, sulfenamide compounds. , Dithiocarbamate compounds, aldehyde amine compounds, guanidine compounds, thiourea compounds,
Vulcanization accelerators such as xanthate compounds can be used.

The heat treatment after the coating of the graphite layer 7d is performed by the rubber and rubber chemicals in the compound and the synthetic resin mixed in the graphite layer 7d. This is performed in order to cross-link by reacting the graphite layer 7d).

The thickness of each part of the cylinder head gasket 2 of this embodiment before tightening is as follows.

The thickness t ₃ ... 0 of the thickness of the thickness t _9b ... 0.45 mm surface board 9c of the plate thickness t _9a ... 0.9 mm surface plate 9b of the core plate 9a t _9c ... 0.45 mm grommet 3. the thickness t _7d of 45mm metal plate 7a of the plate thickness t _7a ... 1.4 mm layer and the graphite layer 7d layer 7c and the adhesive 7b compounding thickness of the sum _t 7bcd ... 0.215mm graphite layer 7d ... 2～3Myu the total plate thickness t ₇ ... 1.83 mm Fire ring 7 also TokibanAtsu t _B tightening grommet 3 (see FIG. 7) is defined to be 1.7 ± 0.04 mm. Accordingly, the plate thickness t _7a of the metal plate 7a of the fire ring 7 is made smaller than the plate thickness t _B of the bore grommet 3 at the time of tightening, while the total plate thickness t ₇ of the fire ring 7 before tightening is the bore grommet. 7.6% are thicker than TokibanAtsu t _B with 3 parts of tightening.

It is needless to say that the thickness of each part in the present invention is not limited to the specific numerical value of the above embodiment.

As shown in FIG. 5, the outer peripheral surface 15 of the fire ring 7 is concave, and the outer peripheral surface 15 is fitted to the inner peripheral surface of the convex bore grommet 3. Therefore, the fire ring 7 is mounted on the gasket main body 9. As shown in FIG. 4, a portion of the inner periphery of the metal plate 7a corresponding to the valve mounting portion 16 of the cylinder head 4 is concavely formed in a circular arc shape when viewed from above to form a concave portion 17. .

In this cylinder head gasket 2, the total thickness t ₇ of the fire ring 7 before tightening is:
Since the bore grommet 3 is thicker than the fastening plate thickness t _B , when the bore grommet is fastened by being interposed between the cylinder head 4 and the cylinder block 6 as shown in FIG. The layer 7c is compressed between the cylinder head 4 and the cylinder liner 1, and both surfaces of the fire ring 7 are in close contact with the lower surface of the cylinder head 4 and the upper surface of the cylinder liner 1, respectively. Therefore, the dead volume can be completely removed.

Since the layer of the compound 7c contains a compressible organic fiber, a compressible inorganic fiber and a rubber, and has a high compressibility, it fits into the fire ring 7 with respect to the lower surface of the cylinder head 4 and the upper surface of the liner 1. The dead volume can be completely removed from this point as well.

The lower surface of the cylinder head 4 and the upper surface of the cylinder liner 1 come into contact with both surfaces of the fire ring 7, but as described above, the compound layer 7c is highly compressible, so that no excessive surface pressure occurs. More specifically, the tightening plate thickness t _B of the three parts of the bore grommet is normally regulated to about ± 0.04 mm from the engine output securing surface. As shown in the figure, the surface pressure of the fire ring 7 is 100 to 350.
It is about Kgf / cm ^2, and does not cause excessive surface pressure. Therefore, the gas sealability is not reduced, the deformation of the cylinder bore is increased, and the liner 1 is not cracked.

As described above, the compound layer 7c
Since a high compressibility, even if variations in TokibanAtsu t _B tightening grommet 3 parts, variations in the load surface pressure fire ring 7 parts is small.

FIG. 8 is a comparison of the compression characteristics of the fire ring 7 of this embodiment and the fire ring 7 (made of SPCC, 1.75 mm in thickness) of FIG. is there. In this figure, a curve B shows the relationship between the compressive load and the compressive strain of the fire ring 7 of this embodiment, and a curve C shows that of the conventional fire ring 7 of FIG.

Table 1 shows the surface pressure of the fire ring 7 of this embodiment and the conventional fire ring 7 of FIG. 3, and the plate thickness t _B when the bore grommet 3 was tightened was 1.66 m.
m, 1.70 mm, 1.74 mm
This is calculated and shown.

[0042]

[Table 1] Generally, the temperature of the lower surface of the cylinder head 4 and the upper surface of the liner 1 is about 200 ° C. However, the compound layer 7c is composed of compressible organic fibers, compressible inorganic fibers,
Since it contains an inorganic filler and rubber, it has a heat resistance of 400
Since it can be set to about ° C, it has sufficient heat resistance.

In this embodiment, the compound layer 7
Since the graphite layer 7d is formed on the surface of c,
The upper and lower surfaces of the fire ring 7 are prevented from sticking to the lower surface of the cylinder head 4 and the upper surface of the cylinder liner 1, and during operation, the movement of the lower surface of the head 4 and the upper surface of the liner causes the fire ring 7 including the compound layer 7c to move. It rarely deteriorates.

[0044]

As described above, according to the present invention, (b) a cylinder liner capable of completely removing a dead volume, thereby reducing the concentration of HC in exhaust gas and improving fuel efficiency. There is no need to process the protrusion on the upper part of the cylinder, (c) there is no decrease in gas sealability, increase in cylinder bore deformation and no cracks in the liner part, and (d) the thickness of the bore grommet part at the time of tightening varies. In addition, excellent effects such as a small variation in the load surface pressure of the fire ring portion and (e) sufficient heat resistance can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a cylinder structure of a conventional engine.

FIG. 2 is a cross-sectional view showing another example of a cylinder structure of a conventional engine.

FIG. 3 is a sectional view showing still another example of the cylinder structure of the conventional engine.

FIG. 4 is a plan view showing one embodiment of a cylinder head gasket according to the present invention.

FIG. 5 is a sectional view taken along line VV in FIG. 4;

FIG. 6 is an enlarged sectional view showing a part of a fire ring in the embodiment.

FIG. 7 is a sectional view showing a cylinder structure of an engine equipped with the cylinder head gasket of the embodiment.

FIG. 8 is a characteristic diagram showing compression characteristics of the fire ring of the embodiment and the conventional fire ring of FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cylinder liner 2 Cylinder head gasket 3 Bore grommet 7 Fire ring 7a Metal plate 7c Compound layer 7d Graphite layer 9a Core plate 11 Cylinder hole t _B Plate thickness at the time of tightening of bore grommet part t ₇ Total thickness of fire ring t _7a Metal plate thickness

Claims (3)

[Claims] 1. A core plate made of metal, a cylinder hole provided in the core plate, a bore grommet made of metal mounted on a peripheral portion of the cylinder hole, and a bore grommet mounted on an inner peripheral side of the bore grommet. The fire ring comprises a metal plate, and a compressive inorganic fiber other than asbestos, a compressible organic fiber, a compressible organic fiber, an inorganic filler and a rubber coated on both surfaces of the metal plate. The thickness of the metal plate of the fire ring is smaller than the thickness of the bore grommet portion when tightened, while the total thickness of the fire ring before tightening is A cylinder head gasket which is thicker than a plate thickness when the bore grommet portion is tightened. 2. The total thickness of the fire ring before tightening is 4 to 1 more than the thickness of the bore grommet portion at the time of tightening.
The cylinder head gasket according to claim 1, which is 2% thicker. 3. The method according to claim 1, wherein the surface of the compound layer is coated with a layer mainly composed of graphite.
Or the cylinder head gasket according to 2.