JP2020128737A - Seal component for engine intake system and seal structure for engine intake system - Google Patents

Abstract

To provide a seal component for engine intake system having durability even under an environment containing a polycyclic aromatic component while using hydrogenated nitrile-based rubber having fuel resistance and heat resistance, and a seal structure for engine intake system.SOLUTION: The present invention relates to a seal component for engine intake system to be appropriately used for a seal (a member of code 1) of a direct connection part between a cylinder head 3 and an intake manifold 2 of an engine. The seal component for engine intake system contains: a hydrogenated nitrile rubber of which the bonded acrylonitrile amount ranges from 15% to 20.5% on a mass basis and the hydrogenation rate is 93% or higher; and an inorganic filler of which the blending amount is at least 125 pts.mass or more with respect to 100 pts.mass of polymers, and a hardness thereof is adjusted within a range of 63-77. The present invention also relates to a seal structure for engine intake system employing the same.SELECTED DRAWING: Figure 1

Description

The present invention relates to a seal component for an engine intake system and a seal structure for an engine intake system.

Conventionally, hydrogenated nitrile rubber has been used for seal components of engine intake systems from the viewpoint of fuel resistance (oil resistance) and heat resistance.
On the other hand, there is a tendency that a large amount of blown back fuel is blown back from the combustion chamber to the intake system due to direct injection of fuel, complication of valve timing, and the like accompanying the demand for improvement in fuel consumption.

The blow-back fuel contains a polycyclic aromatic component that is secondarily generated in the combustion chamber, and the polycyclic aromatic component adheres to and impregnates the hydrogenated nitrile rubber seal component. .. The polycyclic aromatic component acts as a nucleating agent for crystallization of the hydrogenated nitrile rubber itself in the hydrogenated nitrile rubber, crystallizes and cures. As a result, the sealing component made of hydrogenated nitrile rubber in the compressed state loses rubber elasticity and impairs the sealing function.

In order to improve this problem, it is common to use fluororubber or fluorosilicone rubber that is not affected by polycyclic aromatic components as the material for the seal parts, but compared to the case of using hydrogenated nitrile rubber. Therefore, the cost will be greatly increased.

Further, in Patent Document 1, α,β-ethylenically unsaturated nitrile monomer units, diene monomer units, α,β-ethylenically unsaturated dicarboxylic acid monoester monomer units and other α,β, It has a β-ethylenically unsaturated carboxylic acid ester monomer unit, an α,β-ethylenically unsaturated nitrile monomer unit content of 21.0 to 23.0% by weight, and an iodine value of 120 or less. A polyamine vulcanizable highly saturated nitrile rubber is blended with 4 to 31 parts by mass of an aliphatic carboxylic acid diester compound of polyalkylene glycol per 100 parts by mass of the polyamine vulcanizable nitrile rubber. A polyamine vulcanizable highly saturated nitrile rubber composition having excellent properties is disclosed. However, in the present composition, the blow-back fuel containing a larger amount of polycyclic aromatic component has a low effect of improving the low-temperature sealing property and is not sufficient.

In particular, regarding the seal at the direct connection part between the engine cylinder head and the intake manifold, the distance from the engine combustion chamber is short, and the polycyclic aromatic component is more likely to be exposed to blowback fuel. A seal structure that is as resistant to the components as possible is desired.

International Publication No. 2013/175878

Therefore, the present invention provides a seal component for an engine intake system which uses a hydrogenated nitrile rubber having fuel resistance and heat resistance and has durability even in an environment having a polycyclic aromatic component. With the goal.
Another object of the present invention is to provide a seal structure for an engine intake system that has a resistance to polycyclic aromatic components as high as possible.

In order to solve the above problems, according to one aspect of the present invention relating to an engine intake system seal component,
The amount of bound acrylonitrile is in the range of 15% to 20.5% on a mass basis, and the hydrogenation rate is 93% or more, and the compounding amount is 125 parts by mass with respect to at least 100 parts by mass of the polymer content. Including the above inorganic filler,
Provided is a seal component for an engine intake system, which has a hardness adjusted to a range of 63 to 77 degrees.

According to one aspect of the present invention related to the engine intake system seal component described above, the amount of bound acrylonitrile, which is easily affected by the polycyclic aromatic component, is greatly reduced, and crystallization due to the polycyclic aromatic component is suppressed. Since other performances such as heat resistance, fuel resistance, and durability can be secured, it is possible to provide an engine intake system seal component having higher resistance to polycyclic aromatic components.

In one embodiment of the present invention, it is desirable that it be peroxide-vulcanized or amine-vulcanized. According to the engine intake system seal component obtained by these vulcanization methods, resistance to compression set, that is, creep property (settling property) can be improved.

In one aspect of the present invention, it is preferable that a nitrile rubber having a bound acrylonitrile amount of 20% or more on a mass basis is blended within 30% by mass with respect to the hydrogenated nitrile rubber. By mixing the non-hydrogenated nitrile rubber component that is less likely to be affected by the polycyclic aromatic component within a range that does not easily affect the heat resistance, the resistance to the polycyclic aromatic component can be further increased.

The engine intake system seal component according to an aspect of the present invention can be particularly preferably used for sealing a direct connection portion between an engine cylinder head and an intake manifold. Since the location is easily exposed to blowback fuel containing a polycyclic aromatic component, durability is improved by using the engine intake system seal component according to one embodiment of the present invention having high resistance to the polycyclic aromatic component. improves.

On the other hand, according to one aspect of the present invention related to the seal structure of the engine intake system,
A seal structure for the direct connection between the engine cylinder head and the intake manifold,
The intake manifold has a seal mounting groove,
The engine intake system seal component according to an aspect of the present invention is mounted in the seal mounting groove with a part thereof protruding, and the protruding end portion is directly connected to the intake manifold in the cylinder head. It is pressed by the surface that becomes the part
In a cross section of the seal mounting groove, a rectangle surrounded by the cylinder head, the seal mounting groove, and extensions of both side surfaces thereof, in a state where the engine intake system seal parts are in contact with both side surfaces of the seal mounting groove. The ratio (y/x) of the area (y) of the cross section of the engine intake system seal component to the cross sectional area (x) of the seal space (hereinafter, sometimes referred to as “rectangular seal space”) of A seal structure for an engine intake system is provided, which is in the range of 0.75 to 0.90.

According to the above aspect of the present invention related to the seal structure of the engine intake system, the existing area of the seal component for the engine intake system with respect to the area of the rectangular seal space in the direct connection portion between the cylinder head of the engine and the intake manifold. The ratio (hereinafter, sometimes referred to as “filling ratio”) is increased as much as possible while securing a margin, thereby ensuring proper sealing performance while suppressing compression deformation of the engine intake system seal component. can do.

In the engine intake system seal structure according to the aspect of the present invention, it is preferable that the intake manifold is made of resin.
By using a resin intake manifold, a complicated seal groove shape and layout can be manufactured accurately in a short time in a single molding process. Therefore, as a result, a high sealing property can be secured at low cost.

As described above, according to the engine intake system seal component of the present invention, it is possible to obtain higher resistance to polycyclic aromatic components.
Further, according to the engine intake system seal structure of the present invention, the resistance to the polycyclic aromatic component can be made as high as possible.

FIG. 4 is a partial cross-sectional view of the vicinity of the cylinder head of the engine, showing a state in which the engine intake system seal component of the embodiment according to the present invention is applied to the seal of the direct connection portion between the cylinder head and the intake manifold. It is an expanded sectional view of a direct connection part of a cylinder head and an intake manifold. FIG. 3 is a further enlarged cross-sectional view in the vicinity of the engine intake system seal component in the direct connection portion of FIG. 2. It is an expanded sectional view of the engine intake system seal components manufactured in the example. It is a schematic cross section which shows the use condition of the aluminum jig used for the evaluation test in an Example.

Hereinafter, the engine intake system seal component of the present invention will be described in detail and its application will be described, and the engine intake system seal structure of the present invention will be described with reference to preferred embodiments.

[Ingredients]
The engine intake system seal component of the present invention (hereinafter, may be simply referred to as "the seal component of the present invention") contains hydrogenated nitrile rubber as a polymer and an inorganic filler as essential components, Other ingredients are included depending on the purpose and requirements.

<Polymer>
The seal component of the present invention contains hydrogenated nitrile rubber as a main component polymer, and in particular, the amount of bound acrylonitrile is within the range of 15% to 20.5% on a mass basis, and the hydrogenation rate is 93% or more. Contains hydrogenated nitrile rubber as a main component.

In the seal part of the present invention, the amount of bound acrylonitrile of the hydrogenated nitrile rubber used is in the range of 15% to 20.5% on a mass basis, but preferably in the range of 15% to 18%. If the amount of bound acrylonitrile is too large, the resistance to polycyclic aromatic components tends to be insufficient, and if the amount of bound acrylonitrile is too small, there is a concern that basic performance such as fuel resistance will be insufficient as a seal component.

The hydrogenation rate of the hydrogenated nitrile rubber used is 93% or more, preferably 95% or more. By increasing the hydrogenation rate, the fuel resistance and heat resistance for the engine intake system can be improved. As the hydrogenated nitrile rubber having a bound acrylonitrile amount of 15% to 20.5% on a mass basis and a hydrogenation rate of 93% or more, a single structure may be used. You may use together the thing of a kind of structure.

A non-hydrogenated nitrile rubber (hereinafter, simply referred to as “nitrile rubber” means a non-hydrogenated one) may be used together with the polymer. The combined use of nitrile rubber, which is not easily affected by the polycyclic aromatic component, can be expected to have the effect of improving the resistance to the polycyclic aromatic component.

As the nitrile rubber used at this time, the amount of bound acrylonitrile is preferably 20% by mass or more, and more preferably 25% by mass or more and 42% by mass or less. If the amount of bound acrylonitrile in the nitrile rubber used is too small, the fuel resistance may be insufficient, and if it is too large, mechanical properties deteriorate due to poor low temperature resistance and poor dispersion with hydrogenated nitrile rubber. There is a fear.

The amount of nitrile rubber used in combination is preferably 30% by mass or less, more preferably 15% by mass or more and 30% by mass or less, based on the hydrogenated nitrile rubber. If the blending amount of the nitrile rubber is too large, the fuel resistance and heat resistance may be insufficient, and if it is too small, the effect of improving the resistance to the polycyclic aromatic component due to the combined use cannot be expected.

In the present invention, as the hydrogenated nitrile rubber and the polymer other than the nitrile rubber, other polymers may be mixed as long as the function as the seal component of the present invention is not impaired. Examples of the polymer that can be mixed include vinyl chloride resin, ethylene pyropyrene rubber, ethylene propylene diene rubber, fluororubber, chloroprene rubber, epichlorohydrin rubber and acrylic rubber.

<Inorganic filler>
The sealant of the present invention contains an inorganic filler. Here, the "inorganic filler" is added to the rubber component to increase the amount thereof, and exerts almost no chemical action (excluding simple electrostatic influence) on the rubber component. Refers to inorganic solids.

Examples of suitable inorganic fillers used in the present invention include carbon black, silica, calcium carbonate, kaolin, talc, mica, wollastonite, montmorillonite, sericite, pyrophyllite, and alumina. .. Among these, carbon black, silica, calcium carbonate and kaolin are particularly preferable.

The blending amount of the inorganic filler is 125 parts by mass or more with respect to 100 parts by mass of the polymer content, preferably 125 parts by mass or more and 200 parts by mass or less, and 135 parts by mass or more and 190 parts by mass or less. It is more preferably within the range. By mixing the inorganic filler in a predetermined amount or more, the influence of the polycyclic aromatic component can be suppressed and the resistance can be improved. On the other hand, if the blending ratio of the inorganic filler is too large, it becomes difficult to secure appropriate hardness, flexibility and compression set as a sealing material.

<Other ingredients>
In addition to the above-described essential components or main components, the seal component of the present invention can be blended with other components such as various known additives. Examples of other components that can be blended include conventionally known plasticizers, antioxidants, processing aids, acid acceptors, coupling agents, and pigments.

Further, a vulcanizing agent or a vulcanization accelerator may be added to vulcanize the hydrogenated nitrile rubber and the nitrile rubber. In the present invention, peroxide vulcanization or amine vulcanization is preferably performed for vulcanization of hydrogenated nitrile rubber and nitrile rubber. In general vulcanization with sulfur, there is a concern that resistance to compression set, that is, creep property (settling property) may cause a problem, but to improve such a problem by performing peroxide vulcanization or amine vulcanization. You can

As a vulcanizing agent when performing peroxide vulcanization, di-cumyl peroxide, di-t-butyl peroxide, benzoyl peroxide, t-butyl peroxybenzoate, 2,5-dimethyl-2,5-di (T-Butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)-hexyne-3, α,α′-bis(t-butylperoxy)-p-diisopropylbenzene Etc. can be mentioned. Further, as a vulcanization accelerator when performing peroxide vulcanization, ethylene glycol dimethacrylate (EDMA), trimethylolpropane trimethacrylate (TMPT), triallyl cyanurate (TAC), triallyl isocyanurate (TAIC) ) And the like.

Examples of the vulcanizing agent when performing amine vulcanization include polyvalent amines such as hexamethylenediamine, hexamethylenediamine carbamate, and hexamethylene benzoate. Moreover, 1,8-diazabicyclo[5,4,0]undecene 7 (DBU), 1,5-diazabicyclo[4,3,0]nonene 5 (DBN) is used as a vulcanization accelerator when performing amine vulcanization. ) And other basic vulcanization accelerators.

[hardness]
The seal component of the present invention is produced by the above-mentioned composition and is adjusted so that the hardness after production is in the range of 63 to 77 degrees. The hardness is preferably adjusted to fall within the range of 65 to 75 degrees, and more preferably adjusted to fall within the range of 67 to 73 degrees. By setting the hardness within an appropriate range, it is possible to secure flexibility as a seal part and suppress creep during long-term use, and it is possible to obtain a seal part having practicality.
The "hardness" referred to here is the hardness defined by JIS K6253-3 "Vulcanized rubber and thermoplastic rubber-Method of determining hardness-Part 3: Durometer hardness".

Examples of the method for adjusting the hardness of the seal component of the present invention after production include adjustment by appropriately selecting the proportions and types of various compounding components (particularly, inorganic fillers and plasticizers) and vulcanizing agents. The crosslinking density can be adjusted by appropriately selecting the ratio and type of the vulcanization accelerator, and the like, but the method is not limited to these.

[Production method]
The seal component of the present invention can be manufactured as follows. That is, the above components except the vulcanizing agent and the vulcanization accelerator are mixed, and the compound A kneading is prepared with a kneader such as a kneader or a Banbury mixer. After that, a vulcanizing agent (further a vulcanization accelerator if necessary) is added, and B kneading is carried out to finish the kneaded material. The obtained dough may be put into a seal-shaped mold and subjected to press molding vulcanization, injection molding vulcanization, or extrusion molding + electric furnace or steam vulcanization.
Further, it is preferable to stabilize the crosslink density (state) by performing secondary vulcanization.

[Uses of Sealing Parts for Engine Intake System of the Present Invention]
The seal component of the present invention is used in an engine intake system. In particular, it is preferably used for sealing a direct connecting portion between an engine cylinder head and an intake manifold.

FIG. 1 is a partial cross-sectional view in the vicinity of a cylinder head of an engine, showing a state in which a seal component according to an embodiment of the present invention is applied to a seal at a direct connecting portion between a cylinder head and an intake manifold. Each cylinder 6 of the engine has a piston 7 therein, and when the piston 7 moves up and down, the mixture of fuel and air in the combustion chamber 8 is sucked, compressed, expanded, and discharged. ing.

In the following examples, a 4-stroke (4-cycle) engine that uses gasoline as a fuel is taken as an example, but the present invention can be applied to a 2-stroke (2-cycle) engine or a diesel engine without a spark plug. The seal component of such an embodiment can be applied without any problem.

The cylinder head 3 is provided above the cylinder 6. The cylinder head 3 is provided with intake and exhaust passages A and B, and the intake passage A is in a sealed state by an intake valve 5a and the exhaust passage B is an exhaust valve 5b in principle. The intake passage A communicates with the intake manifold 2, and the fuel injection device 4 is provided on the way.

The outside air is sent from the intake manifold 2 to the cylinder head 3, and the fuel is injected and mixed by the outside air into the cylinder head 3 to generate an air-fuel mixture. The generated air-fuel mixture is supplied into the combustion chamber 8 from the intake valve 5a that is opened in a protruding state with respect to the combustion chamber 8. At this time, the piston 7 descends from the upper end toward the lower end and acts so as to suck the air-fuel mixture into the combustion chamber 8 (intake stroke).

When the intake of the fuel is completed, the intake valve 5a is closed, the piston 7 is inverted and moved upward, and the air-fuel mixture in the combustion chamber 8 is compressed (compression stroke). At the end of the compression process, that is, when the piston 7 reaches the upper end, or before and after that, the air-fuel mixture in the combustion chamber 8 is ignited by an ignition plug (not shown), and the air-fuel mixture explodes. Then, the explosive expansion force of the air-fuel mixture at that time expands the inside of the mixer 8 and pushes down the piston 7 (expansion stroke).

When the piston 7 reaches the lower end, the exhaust valve 5b is opened in a protruding state with respect to the combustion chamber 8, and as the piston 7 rises, the air-fuel mixture (combustion gas) after combustion in the combustion chamber 8 is exhausted through the exhaust path B. Is pushed out (exhaust stroke). When the piston 7 reaches the upper end and the combustion gas in the combustion chamber 8 is pushed out, the exhaust valve 5b is closed and the cycle proceeds from the next intake stroke.

During the exhaust stroke, the combustion gas remaining in the combustion chamber 8 contains incomplete combustion components. Due to various structural and driving conditions, this incomplete combustion component is blown back to the intake passage A when the intake valve 5a is opened immediately before the start of the intake stroke. This is called "blowback fuel". The blown-back fuel contains a polycyclic aromatic component that is secondarily produced in the combustion chamber.

The blowback fuel may reach the direct connection portion between the cylinder head 3 and the intake manifold 2. The seal component (engine intake system seal component) 1 according to the present embodiment is preferably used for the seal of the direct connection portion (the embodiment of the engine intake system seal structure according to the present invention).

FIG. 2 shows an enlarged cross-sectional view of a direct connection portion between the cylinder head 3 and the intake manifold 2. Around the tip opening of the intake manifold 2, a seal mounting groove 21 is formed so that the groove opening faces the cylinder head 3 so as to surround the tip opening. The annular seal component 1 is fitted into the seal mounting groove 21 with a part thereof protruding from the opening of the groove. Then, the protruding seal component 1 is pressed by the surface of the cylinder head 3, which is a mating member, which is the direct connecting portion, and the direct connecting portion between the cylinder head 3 and the intake manifold 2 is sealed.

FIG. 3 shows a further enlarged sectional view in the vicinity of the seal component 1. A state in which the ring-shaped seal component 1 having an elliptical cross section is mounted in the seal mounting groove 21 provided so as to surround the front end opening of the intake manifold 2 is illustrated. At this time, the end of the seal component 1 protruding from the seal mounting groove 21 is pressed by the surface of the cylinder head 3. Further, in the cross section of the seal mounting groove 21, the seal component 1 is in contact with both side surfaces 22 of the seal mounting groove 21.

At this time, the seal with respect to the cross-sectional area (x) of the rectangular seal space 11 surrounded by the cylinder head 3, the seal mounting groove 21, and the extension of both side surfaces 22 thereof (broken line between the cylinder head 3 and the intake manifold 2). The ratio of the existing areas of the cross section (y) of the component 1 (filling ratio=y/x) is preferably in the range of 0.75 to 0.90, and is in the range of 0.78 to 0.87. Is more preferable. By setting the filling ratio within the appropriate range, it is possible to secure the proper sealing property while suppressing the compressive deformation of the seal component 1.

Generally, the cylinder head 3 of an engine is manufactured by casting aluminum or iron because of quality requirements such as heat resistance and rigidity dimensional accuracy. On the other hand, since the intake manifold 2 is a component of the intake system, it is not required to have high heat resistance and rigidity as high as that of the cylinder head 3, so that in recent years, the use of resin has been increasing. Since the intake manifold 2 is made of resin, it has high suitability for manufacturing, contributes to weight reduction of the engine, and enables complicated seal groove design, so that high sealing performance can be secured at low cost. Specific resins that can be used for the intake manifold 2 include polyamide 66, polyamide 6, aromatic polyamide, polypropylene and the like. Whichever resin is used, it is preferably a resin reinforced with glass fiber or carbon fiber in order to improve its mechanical strength.

Although the engine intake system seal component and the engine intake system seal structure of the present invention have been described above with reference to the preferred embodiments, the engine intake system seal component and the engine intake system seal structure of the present invention are described. Is not limited to the configuration of the above embodiment.
For example, in the above embodiment, an example in which the cross-sectional shape of the seal component is an elliptical shape has been described, but the present invention is not limited to this, and various cross-sectional shapes can be applied. For example, there is no problem even with the seal component 10 having the cross-sectional shape shown in FIG. Any other cross-sectional area can be adopted, and there is no problem as long as the sealability can be ensured, and a good sealability can be suitably adopted.

In addition, those skilled in the art can appropriately modify the engine intake system seal component of the present invention and the engine intake system seal structure according to the conventionally known knowledge. Such modifications are, of course, included in the scope of the present invention as long as the engine intake system seal component of the present invention and the structure of the engine intake system seal structure are provided.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to the examples.

(Example 1)
First, the following raw materials were prepared.
Hydrogenated nitrile rubber (“Zetpol 158T” manufactured by Nippon Zeon Co., Ltd., amount of bound acrylonitrile (mass standard) 16.4%, hydrogenation rate 95.2%): 100 parts by mass Silica (manufactured by Tosoh Silica Corporation “ Nispil ER"): 55 parts by mass of calcium carbonate (Shiraishi Calcium Co., Ltd., "Shirotanka CC"): 55 parts by mass of clay Kaolin clay (Shiraishi Calcium Co., Ltd. of "KAOFINE"): 50 parts by mass of plasticizer, trimellitic acid Tris(2-ethylhexyl) (manufactured by Mitsubishi Chemical Corporation): 35 parts by mass/aging inhibitor 4,4′-bis(α,α-dimethylbenzyl)diphenylamine (“Nocrac CD” manufactured by Ouchi Shinko Chemical Industry Co., Ltd.) 3. 1.5 parts by mass vulcanizing agent Hexamethylenediamine carbamate ("Diak #1" manufactured by DuPont): 2.1 parts by mass vulcanization accelerator ("Legnolan XLA-60" manufactured by LANXESS Co., Ltd.): 0 parts by mass

Vulcanization by finely adjusting the respective compounding amounts of silica, calcium carbonate, clay and plasticizer so that the rubber hardness becomes 70 degrees (according to JIS K6253-3) without changing the total compounding amount of the inorganic filler. An A kneading compound was prepared by introducing the compounding ingredients excluding the vulcanizing agent and the vulcanization accelerator into a 1 liter kneader and kneading. Then, a vulcanizing agent and a vulcanization accelerator were blended, and B was kneaded with a 6-inch roll to prepare a rubber compound.

The obtained rubber compound was filled in a mold having a cross-sectional shape of the seal component 10 shown in FIG. 4 (a filling ratio of 83% to a rectangular seal space of a test jig 20 or 30 shown in FIG. 5 described later), and 170 After press vulcanization at 20° C. for 20 minutes, secondary vulcanization was further performed at 170° C. for 2 hours in an electric furnace to obtain a seal part of Example 1.

(Example 2)
As a hydrogenated nitrile rubber, instead of "Zetpol 158T" manufactured by Nippon Zeon Co., Ltd., "Zetpol 3610" manufactured by Nippon Zeon Co., Ltd. (amount of bound acrylonitrile (mass basis) 20.5%, hydrogenation rate 95.2%) was used. The amount of each of silica, calcium carbonate, kaolin clay, and a plasticizer was changed so that the rubber hardness was 70 degrees (according to JIS K6253-3) without changing the total amount of the inorganic filler. A sealing component of Example 2 was obtained in the same manner as in Example 1 except that it was adjusted appropriately.

(Example 3)
55 parts by mass of silica (“Nispil ER” manufactured by Tosoh Silica Co., Ltd.), 35 parts by mass of calcium carbonate (“Shiratsuka CC” manufactured by Shiraishi Calcium Co., Ltd.), clay kaolin clay (Shiroishi Calcium Co., Ltd.) The production of “KAOFINE”) was 35 parts by mass, and the total amount of the inorganic filler was 125% by mass, except that the sealing component of Example 3 was prepared in the same manner as in Example 1. Obtained.

(Example 4)
As a polymer, 30 parts by mass of nitrile rubber (“Nipol DN2850” manufactured by Nippon Zeon Co., Ltd., bound acrylonitrile amount (mass standard) 28%) was added, and the rubber hardness was 70 degrees (according to JIS K6253-3). In the same manner as in Example 1, except that the respective amounts of silica, calcium carbonate, kaolin clay and plasticizer were adjusted appropriately without changing the total amount of the inorganic filler. The sealing part of Example 4 was obtained.

(Example 5)
A stainless steel spacer having a thickness of 0.1 mm is arranged on the bottom of the seal mounting groove 23 of the jig 20 shown in FIG. 5 described later (apparently in FIG. 5, the ceiling surface of the seal mounting groove 23; the same as in Example 7). In the same manner as in Example 1 except that the seal mounting groove 23 was raised to the bottom and compression sealing was performed so that the filling ratio of the jigs 20 and 30 for testing to the rectangular seal space was 90%. I got the seal parts.

(Example 6)
As the polymer, 50 parts by mass of nitrile rubber (“Zetpol DN2850” manufactured by Nippon Zeon Co., Ltd., bound acrylonitrile amount (mass basis) 28%) was added, and the rubber hardness was 70 degrees (according to JIS K6253-3). In the same manner as in Example 1, except that the respective amounts of silica, calcium carbonate, kaolin clay and plasticizer were adjusted appropriately without changing the total amount of the inorganic filler. The sealing part of Example 6 was obtained.

(Example 7)
A 0.5 mm-thick stainless steel spacer is arranged on the bottom of the seal mounting groove 23 of the jig 20 shown in FIG. A seal part of Example 5 was obtained in the same manner as in Example 1 except that compression sealing was performed so that the filling ratio was 93%.

(Comparative Example 1)
As the hydrogenated nitrile rubber, instead of "Zetpol 158T" manufactured by Nippon Zeon Co., Ltd., "Zetpol 3710" manufactured by Nippon Zeon Co., Ltd. (amount of bound acrylonitrile (mass standard) 23.4%, hydrogenation rate 95.2%) was used. The amount of each of silica, calcium carbonate, kaolin clay, and a plasticizer was changed so that the rubber hardness was 70 degrees (according to JIS K6253-3) without changing the total amount of the inorganic filler. A sealing component of Comparative Example 1 was obtained in the same manner as in Example 1 except that the sealing component was appropriately adjusted.

(Comparative example 2)
55 parts by mass of silica (“Nispil ER” manufactured by Tosoh Silica Co., Ltd.), 20 parts by mass of calcium carbonate (“Shiratsuka CC” manufactured by Shiraishi Calcium Co., Ltd.), kaolin clay (manufactured by Shiraishi Calcium Co., Ltd.) The sealing component of Comparative Example 2 was obtained in the same manner as in Example 1 except that the amount of "KAOFINE") was set to 20 parts by mass and the total amount of the inorganic filler was set to 95% by mass. It was

The manufacturing conditions of the seal parts of Examples 1 to 7 and Comparative Examples 1 and 2 are summarized in Table 1 below.

<Evaluation test>
The following evaluation tests were performed using the obtained seal components of Examples 1 to 7 and Comparative Examples 1 and 2. The results are summarized in Table 2 below.

[Polycyclic aromatic component resistance test]
The aluminum jigs 20 and 30 shown in FIG. 5 were prepared. The aluminum jig 30 imitates the cylinder head side of the engine, and the aluminum jig 20 imitates the intake manifold side. The aluminum jig 20 has an elliptical shape with a long axis of 37 mm and a short axis of 25 mm, has a liquid storage portion with a height of 15 mm, and is provided with a seal mounting groove 23 having a width of 3.5 mm and a depth of 5 mm outside the opening edge by 5 mm. Has been.

In the seal mounting groove 23 provided in the aluminum jig 20, the stainless spacers described above only in Examples 5 and 7 are arranged, and then the seal parts 10 of Examples 1 to 7 and Comparative examples 1 to 3 are respectively arranged. After mounting, the jig 30 made of aluminum was pressed against the seal component 10, and the seal component 10 was compressed with a compression margin of 1.5 mm (gap 0.2 mm between the jig 30 made of aluminum and the jig 20 made of aluminum).

A simulated polycyclic aromatic-containing fuel oil (hereinafter referred to as “simulated oil”) is formed in a space formed between the aluminum jigs 20 and 30 and sealed by the sealing component 10 (hereinafter referred to as “accommodation space”). 8 ml) was sealed, kept at 60° C. in an explosion-proof constant temperature bath at 60° C., and left for 72 hours.
The simulated oil is obtained by mixing 20% by mass of phenanthrene with 80% by mass of a mixed solvent (fuel oil C) of 50% by volume of isooctane+50% by volume of toluene.

After that, the simulated oil was extracted from the accommodation space, and the heat treatment was carried out at 110° C. for 24 hours with the seal component 10 set in the aluminum jig 20.
After the heat treatment, the airtightness test was carried out after leaving the jig 20 made of aluminum in the environment of -30° C. for 4 hours.
In the airtightness test, the pressure was increased from -90 kPa to 120 kPa in steps of 10 kPa, and the pressure at which airtight leakage occurred was recorded.

The evaluation criteria are as follows.
◎: 120 kPa or more ◯: 50 kPa or more and less than 120 kPa ×: less than 50 kPa

[Fuel oil resistance]
The aluminum jigs 20 and 30 shown in FIG. 5 used in the polycyclic aromatic component resistance test were also used in the fuel oil resistance test. 8 ml of a mixed solvent of 50% by volume of isooctane+50% by volume of toluene (fuel oil C) was enclosed in the accommodation space of the jig, and the mixture was kept at 60° C. in an explosion-proof constant temperature bath at 60° C. and left for 72 hours.

After that, the fuel oil C was taken out from the accommodation space, and the sealing component 10 was left in the aluminum jig 20 for 4 hours in an environment of −30° C., and then an airtight test was performed.
In the airtight test, the pressure was increased from -90 kPa to 120 kPa in steps of 10 kPa, and the pressure at which airtight leakage occurred was recorded.

The evaluation criteria are as follows.
◎: 120 kPa or more ◯: 50 kPa or more and less than 120 kPa Δ: 30 kPa or more and less than 50 kPa ×: less than 30 kPa

[Compression set]
The aluminum jigs 20 and 30 shown in FIG. 5 used in the polycyclic aromatic component resistance test were also used in compression set. Nothing was stored in the storage space of the jig, and a heat aging test was carried out at 150° C. for 500 hours in a constant temperature bath.

After that, the aluminum jigs 20 and 30 are taken out from the constant temperature bath, left at room temperature for 30 minutes, and then the seal part 10 is removed from the aluminum jig 20 and opened, and the height of the seal part 10 (initially 6.7 mm) is measured. The compression set was calculated from the following equation.
Compression set (%)=(hi-ha)/1.5×100
(In the above formula, hi represents the initial seal height, and ha represents the seal height after heat aging.)

The evaluation criteria are as follows.
◎: Less than 50% ◯: 50% or more and less than 70% △: 70% or more and less than 80% ×: Compression set of 80% or more

1: Seal parts (engine intake system seal parts)
2: Intake manifold 3: Cylinder head 4: Fuel injection device 5a: Intake valve 5b: Exhaust valve 6: Cylinder 7: Piston 10: Seal parts for testing (seal parts for engine intake system)
11: Sealed space 20: Aluminum jig (intake manifold side)
21, 23: Seal mounting groove 22: Both side surfaces 30: Aluminum jig (cylinder head side)

Claims (6)

The amount of bound acrylonitrile is in the range of 15% to 20.5% on a mass basis, and the hydrogenation rate is 93% or more, and the compounding amount is 125 parts by mass with respect to at least 100 parts by mass of the polymer content. A seal component for an engine intake system, comprising the above inorganic filler and having a hardness adjusted to a range of 63 to 77 degrees. The engine intake system seal component according to claim 1, wherein the seal component is peroxide vulcanized or amine vulcanized. The engine air intake system seal component according to claim 1, wherein a nitrile rubber having a bound acrylonitrile amount of 20% or more on a mass basis is blended with the hydrogenated nitrile rubber within 30% by mass. The seal component for an engine intake system according to any one of claims 1 to 3, which is used for sealing a direct connecting portion between an engine cylinder head and an intake manifold. A seal structure for the direct connection between the engine cylinder head and the intake manifold,
The intake manifold has a seal mounting groove,
The engine intake system seal component according to claim 4 is mounted in the seal mounting groove with a part thereof protruding, and the protruding end portion is a direct connection portion with the intake manifold in the cylinder head. Is pressed by the surface that becomes
In a cross section of the seal mounting groove, a rectangle surrounded by the cylinder head, the seal mounting groove, and extensions of both side surfaces thereof, in a state where the engine intake system seal parts are in contact with both side surfaces of the seal mounting groove. The ratio (y/x) of the existing area (y) of the cross-section of the engine intake system seal component to the cross-sectional area (x) of the seal space is in the range of 0.75 to 0.90. The engine intake system seal structure. The engine intake system seal structure according to claim 5, wherein the intake manifold is made of resin.

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