FR2509414A1 - IMPROVED FLAT GASKET AND METHOD OF MANUFACTURING THE GASKET - Google Patents

Abstract

THIS FLAT GASKET INTENDED TO BE PLACED BETWEEN TWO SURFACES TO FORM A WATERPROOF JOINT BETWEEN THESE SURFACES INCLUDES A METAL CORE 14, A PATTERN OF BOLTS 28, 30, FOR EXAMPLE OF SILICONE FIXED BY ADHESION ON THIS CORE, A COATING LAYER 16 ATTACHED TO THE CORE AND COVERING THE BOURRELET PATTERN IN SUCH A WAY THAT THIS PATTERN IS ENCLOSED BETWEEN THE CORE AND THE COATING LAYER, AND OPENINGS 20, PROVIDED IN THE JOINT AROUND WHICH THE BOURRELETS ARE PROVIDED; DURING USE, THE CUSHIONS ARE PROTECTED FROM DIRECT CONTACT WITH SURFACES. THE INVENTION APPLIES IN PARTICULAR TO CYLINDER HEAD GASKETS OF INTERNAL COMBUSTION ENGINES, IN PARTICULAR DIESEL ENGINES.

Description

Laminated cylinder head gaskets comprising a

  central metallic core and one or two sheets of coating

  Tightly fitted with a seal pattern attached to the coating sheets are becoming increasingly important in sealing internal combustion engines. Most commonly, the seal patterns are

  applied by a silk screen process.

  For several reasons, the cover sheets

  These usually require the application of coatings or surface treatment materials in addition to the seal patterns, so that the seal can resist wear corrosion, abrasion and

  disturbance or destruction of the seal pattern.

  Since the seal patterns are frequent

  difficult to adhere to coating sheets

  ment pretreated, that is to say sheets which have undergone surface treatments which may be advantageous for the coating but which may interfere with hardening

  or fixation by adhesion, it is frequently necessary

  apply the waterproof seal patterns and apply

  then apply a coating or a surface treatment material on the joint covering sheet, sometimes

  without covering the waterproof seal pattern This is very

  hit harder and much more expensive and some-

  times less effective than if the coating, the material

  surface treatment where treatment was applied first

  and the seal pattern applied thereafter.

  A flat seal according to the invention can constitute

  a cylinder head gasket for an internal combustion engine.

  The flat seal is adapted to be placed between the cylinder head-

  se and the cylinder block of the engine The flat seal has at least one combustion chamber opening and a series of holes, for example for oil and water The flat seal comprises an expandable metal core and an expandable coating layer substantially the same extent, fixed to one face of the core, preferably rightly

  a coating layer fixed to each of the faces ex-

  bandages of the core A watertight seal pattern is provided

  deformable This pattern may include one or more bulges

  reins facing the face of the core and is located between the face of the core and the coating layer, so that

  the core and the covering layer enclose the beads.

  The seal pattern advantageously surrounds at least one of the holes to enhance the sealing effect of the

  joint in the region of the beads of the pattern.

  When such a cylinder head gasket is compressed

  between a cylinder head and a cylinder block, the seal pattern is protected from direct contact with the cylinder head and

  with the block and, therefore, abrasion, cha-

their and creep.

  The seal pattern is preferably

  elastomeric nature and it surrounds the openings of the cham-

  burners and one or more of the holes.

  Most preferably, the seal pattern is bonded to the core and the coating layer is bonded to the core by pressurized adhesive in an area which closely surrounds the seal pattern and the bead. lateral displacement of the seal pattern and reinforces this pattern when the seal is

  put in compression In addition, this compresses and densi-

fie the coating layer.

  The invention will be described below in more detail with regard to a nonlimiting embodiment and with reference to the appended drawings in which, Figure 1 is a top plan view of a seal applying the principles of l 'invention; Figure 2 is a partial view, in section

  transverse of a Diesel engine using the joint shown

  felt in Figure 1; Figure 3 is a partial plan view of the seal core of Figure 1, with a seal pattern

  waterproof applied to this core; -

  Figure 4 is a partial plan view, ana-

  log to that of Figure 3, of the flat seal of Figure 1, Figure 5 is an enlarged view and in cross section taken roughly along line 5-5 of Figure 4; and Figure 6 is a partial enlarged view of part of Figure 5 when the seal has been

  precompressed in accordance with the invention.

  Referring now to the drawings, there is shown a diesel engine 1 comprising a cylinder head 2 and a cylinder block 3 and using a flat seal 10 which is specially shaped and constructed for use in

  this engine We can see that block 3 includes an opening

  ture of cylinder 4, a cylinder liner 5 and a piston

  ton 6 Engine 1 has several combustion cylinders

  tion 4 of which only one is shown in Figure 2.

  The joint 10 is a laminate and it can be seen that it comprises a metallic core 14 of generally flat shape,

  massive, expandable and two sides of expanded coating

  bles 16, generally flat in shape The core 14 has flat or flat upper and lower faces such as the faces 18, on which the covering sheets are laminated 16 The core can also be punched, stamped or modified on the surface of another way, by

  example by engraving, in desired locations.

  The covering sheets 16 are formed from a compressible composite material for external covering

  for flat joints and can be reinforced with fibers.

  They are laminated on the faces 18 mechanically.

  as or by adhesion, for example by means of a suitable heat activated adhesive Suitable heat activatable adhesives include phenolic-nitrile rubber and polybutyral rubber which is advantageously applied initially on the faces of the coating sheets. coating may include asbestos, glass fibers or other suitable fibrous materials and may use elastomers of the nitrile, neoprene or polyacrylic type

  as a binder Frequently, the binder represents between approxi-

  ron 15 and about 25% of the covering sheet, whether asbestos fibers or other fibers are used, fillers or equivalent substances of organic or inorganic nature In the embodiment shown, the covering sheets 16 have a thickness of about 0.6 mm although, naturally, this thickness can vary with the application. The coating sheets 16 generally resist degradation by oils and coolants, they stop the effects of torsion, reduce creep to a minimum and possess

  good heat resistance.

  The seal 10 is perforated to form combustion chamber openings and holes such as the bolt passage holes 22, and a series of oil and water passages 24 The core can be made of rolled steel

  when cold and its thickness may vary with the application.

  Thicknesses of approximately 0.15 mm to approximately 1.25 mm are typical To reinforce the grip, the faces 18 of

the soul can be phosphated.

  In the embodiment shown, the core 10 has a relief 21 which surrounds the opening 20 of the combustion chamber The seal 10 can then be provided with an annular reinforcement 25 fixed around the relief 21 in a manner known for help close the opening

  of combustion chamber with watertight seal.

  In the embodiment considered, the desired seal pattern 26 is disposed and fixed on one or each of the two faces of the core. The seal pattern 26 can comprise a series of sealing beads 28, 30 applied in areas where it is necessary to exert stronger or increased sealing forces in the application for which the seal 10 is intended Typically, the beads 28 are formed to substantially surround the opening of the combustion chamber and the beads 30 are formed to substantially surround the water and oil passages between the cylinder head and the associated cylinder block Sometimes, due to the configuration of the cylinder head and the block and the location of the bolt passage holes , or for other design reasons, we can be satisfied with a configuration of beads which is not entirely circular or which does not entirely encircle, as has been shown.

in Figures 1 to 3.

  In the embodiment shown, the bulges

  relets 28 and 30 forming the pattern 26 can be formed

  a silicone sealant which is preferably

  rence deposited by a silk screen printing process, for example as described in US Pat. No. 3,477,867, and with a height at the top of the bead from about 0.15 to about 0, 2 mm Silicone can be

  a liquid silicone which is hardenable in two components

  When the sealing beads are deposited and glued to the strongly adherent, dimensionally stable core, they can be deposited in exactly desired locations, with precision and in a way

  reproducible from one joint to another.

  When the seal pattern has been deposited and hardened in a known manner on the two faces 18 of the core 14, the compressible covering sheets 16 are put in place to cover the core and the seal pattern and fixes them to the core by lamination, for example by means of a conventional adhesive layer interposed The adhesive sticks the coating layer to the core and, when the core and the layers are laminated under pressure, the coating layer is compressed and densified in the seal pattern area When

  the soul is phosphated or otherwise appropriately treated

  required to strengthen adhesion, the coating sheets

  They adhere easily and securely to the faces of the core and, depending on the nature of the sealing material which constitutes the seal pattern 26, they may adhere or not adhere to the beads 28 and 30 In any case, the covering sheets and the metallic core enclose or envelop and surround the sealing beads. The covering sheet is advantageously fixed to the face 18 of the core in a zone Z which closely surrounds the beads, to enclose the bead and to oppose any significant lateral movement of the seal pattern and the beads when the seal is

put under compression.

  The wrapping of the beads presents a cer-

  a number of advantages Among these advantages, there is that

  consisting of the displacement or creep of the bump

  relet, when it is made of elastomer, is limited, which reinforces the load-bearing capacity of the bead When the covering layer and the core very closely surround the bead, not only does the creep be restricted but the beads of elastomer tend to exhibit a steeper load-strain curve than that

  would have the same beads if they were free

  exposed on the face of the covering sheet, as in the conventional technique In this way, under compression, the compression of the beads tends to be limited to a certain indentation in the internal or lower surface of the covering sheet, but without creep , so that the bead and the covering which covers it can behave as an element of

  waterproof seal under higher compression loads

  earlier and more effectively than was possible

laughingly.

2509-414

  When using gaskets with patterns

  seal on their faces, this pattern must initial-

  sinking or almost completely embedded in the coating layer before a load can be applied to other areas of the joint.

  with the joint according to the invention, and according to the precornpres-

  existing in the areas of the enveloping beads

  weight, the application of a load in zones other than the zones of beads, can take place substantially

  immediately When the bead pattern is sensi-

  slightly incompressible as are, for example, elastomers such as silicones or other rubbers and when the seal is compressed in the areas of the beads or of the seal pattern, either in service or during manufacture, the coating material which covers the watertight seal pattern and, since it was slightly porous, tends to

  become even more impermeable to the passage of fluids.

  In this way, the coating material in this area has improved sealing properties and improved physical characteristics which are different.

  of those it presents in areas that are immedi-

  diatent adjacent to the bead and pattern areas

waterproof seal.

  In FIG. 5, the seal is shown before.

  compression compression in the areas of the joint pattern

  waterproof and bead However, the seal is pre-

  ference compressed in these areas during the manufacture of

  in such a way that the coating layers are densely

  as shown in Figure 6 This Figure shows that the silicone layer 28 has been pressed into the coating layer 16 and that this coating layer has been compressed in the area of the bead The height Y of the bead, which was substantially equal, in Figure 5, to the projection of the covering layer in the bead area, was significantly reduced, on the

  Figure 6, as indicated by the height X The ratio

  port between heights X and Y is advantageously not more than about 1: 2, that is to say about a half and preferably less As a whole, the surface of the joint is of a profile closer to the flat profile than that of a seal in which the bead is on the surface which improves the sealing characteristics of the seal

over its entire surface.

  Another advantage which is provided by the seal according to the invention consists in that the bead is protected, not only from creep but also from surface phenomena. These phenomena include the

  rupture or disturbance of the beads during the experiment

  dition, handling and installation, as well as the tendency to break or destroy the bead during use in the engine This break may be due to the roughness of the complementary surfaces between which it is a question of establishing a joint waterproof, case in which the tendency to cut and break the bead due to the rough surface condition is strong. Furthermore, it is known that excessive heat tends to adversely affect the sealing bead made of elastomer. last, in the way

  described, the seal pattern is much better isolated

  This is due to the detrimental effects of heat only when the pattern is on the surface of the joint. In addition, in some environments, bead erosion occurs through wear. Although the coatings can be treated to resist corrosion by wear,

  has so far been very difficult to deal with bour-

  sealing reels such as silicone beads using wear-resistant materials,

  because of the difficulty in gaining adherence

  rer an appropriate protective layer on these beads.

  Also, as already mentioned, when the seal pattern is not on the surface, it becomes possible to apply anti-wear coatings and other surface treatments in an easy and inexpensive manner. over the entire surface of a covering sheet, all without having compensated for these treatments

  nor to use additional phases in the manufacturing

  tion of the joint In addition, by filing the joint motif

  waterproof on the core and not on the sheets of coating

  It is no longer necessary to pre-coat the coating sheets with special screen coating materials.

  to facilitate the hardening of stuffing materials

  lets such as silicones, special materials which are now frequently needed due to the tendency of the coating material itself to inhibit hardening The seals according to the invention also provide the possibility of ensuring better control

deformation of the cylinder head.

  Although the seal pattern and padding

  lets have been described as an elastomer of

  silicone type, it is also possible to use other elasto-

  mothers and elastic materials and these elastomers and other materials include nitrile rubber (polybutadiene-nitrile rubber) or neoprene, epoxies such as flexible and rubber-modified epoxies, as well as combinations of these materials Furthermore, since the bead and the covering sheet cooperate, to transmit the sealing forces in the area of each bead, it is possible to envisage the use of more rigid materials which are not necessarily elastic to establish the waterproofing in certain locations or in all locations where a joint must be made

  waterproof with beads The tendency to sink

  cementing the beads in the covering sheet will tend

  also to improve compliance, with a view to sealing-

  of the faces of the covering sheets with those of the

  cylinder head or cylinder block to a degree that they cannot

  would not reach if the beads were on the external surfaces, as in the current technique-

classic.

  In the embodiment shown, the seal pattern and the beads are attached to

  the core and the coverings are then fixed to the core.

  Depending on the materials used, it can also be

  desirable to attach the beads to the coverings equally

  during the layering process.

Claims (9)

  1. Flat seal intended to be placed between two   surfaces to be joined with a tight seal, characteristic   terized in that it comprises: a metal core (14), a seal pattern (26) fixed to the core by adhesion, a coating layer (16) fixed to the core and which covers the pattern a seal so that the seal pattern is enclosed between the core and the coating layer, at least one opening (20, 22) formed in the seal and around which the seal pattern (26) is disposed , so that, in use, this   seal pattern of the flat seal is protected from   direct contact with the surfaces to be brought together seal.   2. flat seal according to claim 1, character-   rised in that said covering layer (16) is fixed to the core in an area which closely surrounds the seal pattern (26) to prevent any significant lateral displacement of said seal pattern when the flat seal is put in compression.   3 flat seal according to claim 2, character-   laughed at in that said seal pattern (26) is made   an elastomeric material which can deform under the   pressure and in that said coating layer (16)   restricts the deformation of this seal pattern.   4 flat seal according to claim 1 intended for an internal combustion engine and adapted to be interposed between the cylinder head and the cylinder blocks of this engine, this seal delimiting at least one opening of   combustion (20) and a series of holes (22, 24), characteristic   laughed in that said seal pattern (26) is deformable and surrounds at least one of the openings (20) or holes (22, 24) to enhance the sealing effect   of said flat seal in the area of said seal pattern - waterproof (26).   5. Flat seal according to claim 4, charac-   terized in that said seal pattern (26) is made of elastomer and surrounds a combustion opening (20) and   at least one of said holes (22, 24).   6 flat seal according to claim 5, characterized in that said seal pattern (26) is fixed to the core (14) by adhesion and that said coating layer (16) is fixed to the core by adhesion in an area which closely surrounds said seal pattern, thereby opposing any notable lateral movement of said seal pattern when the seal dish is put under compression.   7. Method of manufacturing a flat seal intended   to be interposed between two surfaces that it is about   nir seal, characterized in that: there is a seal pattern (26) on the surface of a metal core (14), a compressible coating layer (16) is positioned on said core and on said pattern   waterproof seal so that the waterproof seal pattern   che is enclosed between the core and the coating layer, said flat seal delimiting at least one opening (20) around which said seal pattern (26) is disposed, said coating layer (16) is fixed by adhesion on said core (14) under pressure so that the covering layer (16) is compressed and densified in the region of said seal pattern,   so that, in use, said watertight seal pattern   che of the flat gasket is protected from direct contact with   surfaces to be joined with a waterproof seal.   8 Method according to claim 7, character-   laughed in that said coating layer is attached to   the core (14) by adhesion in an area which surrounds narrowly   said seal pattern (26) to oppose any significant lateral displacement of said seal pattern when the flat seal is put under compression,   in order to limit the compression of said coating layer   when compressed under pressure.   9. Method according to claim 7, character-   rised in that said coating layer (16) is com-   award-winning under pressure during adhesion fixing,   in such a way that the height of the projection of the neck   coating over the seal pattern (26) is not more than about half the   height of this seal pattern.