Seal for the gas-tight mounting of an intake manifold on the cylinder head of an internal combustion engine

A seal of an elastomeric material used to mount an intake manifold in a gas-tight manner on the cylinder head of an internal combustion engine is disclosed. The seal is formed to blend together in one piece and is located in position on the side of the intake-manifold flange facing the cylinder head. The seal has sealing surfaces, which sealingly surround the periphery of the intake pipes of the intake manifold during normal operational use. The sealing surfaces are interconnected by web segments, and at least one of the web segments is designed in one area of its extent to act as a linear tolerance compensation segment, to be flexurally soft and/or capable of folding together.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a seal of an elastomeric material used to 
mount an intake manifold in a gas-tight manner on the cylinder head of an 
internal combustion engine. The seal is formed so as to blend together in 
one piece can be located on the side of the intake manifold flange facing 
the cylinder head. The seal has sealing surfaces, which sealingly surround 
the periphery of the intake pipes of the intake manifold during normal 
operation. 
2. Description of Related Art 
Seals for intake manifolds are generally known and are designed, for 
example, as flat seals. These seals are intended to seal off the 
separating joint between the intake manifold and the cylinder head so as 
to render the joint gas-tight. Such seals, however--when made of 
elastomeric materials--are subject to manufacturing tolerances and 
shrinkage that are conditional upon the process of manufacturing. 
Moreover, water absorption can cause these seals to stretch. The above 
properties require costly assembly procedures, when the aim is to achieve 
good sealing results over a long service life. This is unsatisfactory from 
the standpoint of assembly engineering and economics. These disadvantages 
become even more evident when intake manifolds of polymeric materials are 
used. Since both the seal and the intake manifold are manufactured of a 
plastic material, the manufacturing tolerances and shrinkage often combine 
to make it impossible to fix the seal exactly in position between the 
intake manifold and the cylinder head, which cylinder head is generally 
constructed of a metallic material. Accordingly, it is difficult to 
achieve a good seal between the intake manifold and the cylinder head. 
SUMMARY OF THE INVENTION 
The underlying objective of the present invention is to develop a seal so 
as to guarantee gas-tight mounting of an intake manifold on a cylinder 
head during the entire service life of the internal combustion engine. The 
present invention is especially useful when intake manifolds of a 
polymeric material are used--and provides a good seal in spite of the 
tolerances that are conditional upon manufacturing and the shrinkage that 
occurs following manufacturing of the seal. 
To achieve this objective, the sealing surfaces of the present invention 
are interconnected by web segments, and at least one of the web segments 
is designed in one area to be flexurally soft and/or capable of folding 
together, to compensate for linear tolerances. Manufacturing tolerances 
and material-related shrinkage can be easily compensated for by 
integrating axially flexurally soft and foldable linear-tolerance 
compensation in the seal. To ensure a perfect seal in the area between the 
intake manifold flange and the cylinder head, the linear tolerance 
compensation is arranged outside of the sealing zones, in those web 
segments which interconnect the sealing surfaces, thus creating a 
one-piece formed seal. 
Because the seal is formed in one piece, it is easy to manufacture, easy to 
manipulate during assembly, and is capable of being installed exactly at 
the designated location. 
One advantageous refinement of the present invention provides for the 
linear tolerance compensation feature to have an undulated shape. Since 
the tolerances to be compensated for are within the range of +0.75 to 
-0.25 millimeters, three folds generally suffice for the compensation 
needed. 
The seal is preferably used in applications in which the intake pipe and 
the cylinder head have at least two inlet ports. In the case of an in-line 
four-cylinder engine or a V-8 engine, the seal can be characterized by 
four sealing surfaces that are arranged in series, the two inner sealing 
surfaces being joined by at least one middle web segment and the linear 
tolerance compensation features being arranged in the web segments between 
the outer and the adjacent inner sealing surfaces. It is advantageous that 
the two sealing surfaces which seal off the two inner intake pipes are 
decoupled in terms of tolerance from the outer sealing surfaces. The 
comparatively small length of the two middle sealing surfaces, which are 
joined by a middle web segment, can be easily manufactured while avoiding 
undesirably large tolerances. However, given a one-piece construction of 
the two inner sealing surfaces together with the two outer sealing 
surfaces, no tolerance compensation would mean considerable manufacturing 
expenditure to ensure good sealing results, which is not satisfactory from 
the standpoint of economics. 
A seal having an advantageous linear tolerance compensation can, as 
previously described, be used for an in-line four-cylinder engine, but may 
also be used advantageously for internal combustion engines having three 
or more cylinders. 
Generally, it is possible for the seal to consist of only an elastomeric 
material. To improve the working properties and inherent stability, the 
sealing surfaces and the middle web segment can be adhesively joined 
and/or connected through form locking to a seal support constructed of a 
polymeric material. This refinement provides the seal with substantial 
inherent stability in those areas used to provide sealing action between 
the intake manifold and the cylinder head and, as a result, makes it easy 
to manipulate the seal so that installation is simplified. 
When a seal support is used, it can be provided in the area of the web 
segments having linear tolerance compensation. The greater inherent 
stiffness of the polymeric material in comparison to the elastomeric 
material guarantees that the linear tolerance compensation is allocated 
with dimensional stability to the seal without losing advantageous working 
properties. 
In another advantageous refinement of the present invention, the seal 
support can be provided on the sides facing the intake manifold and the 
cylinder head with sealing surfaces and have a profile which opens out in 
a U-shape in the direction of the intake manifold and the cylinder head, 
respectively, and which at least partially surrounds the elastomeric 
material. A profile formed in such a manner assures excellent inherent 
stability for the seal during assembly, in which case the seal support has 
at least one, and preferably a plurality, of perforations that are 
penetrated by the elastomeric material of the sealing surfaces. By 
localizing the seal support centrally between the sealing surfaces a 
uniform contact pressure and, therefore, sealing action is produced for 
each sealing surface. 
The lateral sides of the seal support, which project in the direction of 
the intake manifold and the cylinder head, can be designed as limit stops. 
The limit stops each have a smaller extent than the sealing surfaces in 
the same direction. In this manner, during the installation of the seal 
between the intake manifold and the cylinder head, the contact pressure on 
the elastomeric material is limited to a measure that is optimal for a 
sealing action by contact of the limit stops. Moreover, the advantage of 
such a refinement is that the elastomeric material is protected from 
external influences for the entire service life, because it is arranged in 
the U-shaped, opened profile of the seal support. 
The seal support and/or the flexible material of the seal can have at least 
one positioning projection that is premolded in one piece on the side 
facing the intake manifold. This positioning projection can be forced to 
engage a recess in the flange that opens toward the cylinder head. The 
sealing surfaces are preferably provided with positioning projections that 
are distributed uniformly in the circumferential direction to achieve a 
good, gas-tight connection of the intake pipe and the cylinder head in 
this area, which is particularly important for the sealing action. In 
addition, the advantage of the positioning projections is that they enable 
the intake manifold and the seal to be preassembled before the final 
assembly operation. This method is particularly advantageous when the 
intake manifold consists of a polymeric material, since the recesses 
required to accommodate the positioning projections can be directly molded 
during manufacturing. The recesses preferably have a smaller opening 
cross-section than the positioning projections. This refinement allows the 
seal and the intake flange to be press-fit together. This further 
simplifies the installation of the preassembled part on the cylinder head 
of the internal combustion engine. If the positioning projections are made 
in one piece with the seal support, then they penetrate the elastomeric 
material in the direction of the intake manifold. Within the scope of the 
present invention, however, positioning projections are preferably made of 
the elastomeric material of the seal. Overall therefore, the flexibility 
of the positioning projections allows the seal to be easily localized on 
the flange of the intake manifold pipe. 
One advantageous further development provides: 
1. for the middle web segment to be designed as a sealing bridge, 
2. for the seal support and the sealing bridge to be provided with at least 
one shared perforation, 
3. for the perforation to be formed as a connection, and 
4. for one end of the connection to be connected to the crankcase 
ventilation of the internal combustion engine, while the other end of the 
connection is connected to at least one inlet port of the internal 
combustion engine. 
It is advantageous in this case that the connection is integrated directly 
in the seal and that the crankcase gas is fed directly into the intake 
pipes adjacent to the cylinder head. This refinement and the 
heat-radiating cylinder head guarantee that the crankcase gas will be safe 
from icing when it is fed into the intake pipes. Thus, any excessive 
pressure in the crankcase and resultant damage will be reliably avoided. 
At least the sealing surfaces and the sealing bridge are delimited in each 
case by two circumferential sealing lips. These sealing lips are adjacent 
to one another with clearance and protrude in the direction of the surface 
to be sealed. The positioning projections are preferably arranged in the 
area between the sealing lips, which mutually encircle each other. 
Two exemplified embodiments of the seal according to the invention are 
clarified in greater detail on the basis of the enclosed drawings. They 
show the individual components to be considered, partially in a schematic 
representation.

DETAILED DESCRIPTION OF THE DRAWINGS 
A seal 1 made of an elastomeric material, which seals off the separating 
joint between the cylinder head of an internal combustion engine and an 
intake manifold 2 (FIG. 5) of a polymeric material, is shown in each of 
the exemplified embodiments according to FIGS. 1-4. The sealing surfaces 4 
extend in both exemplified embodiments between two sealing lips 17, 18, 
which are mutually adjacent to one another with clearance and surround the 
intake pipes 5 of the intake manifold 2. Positioning projections 12, which 
blend together in one piece and are made of an elastomeric material, are 
arranged in the clearance space between the two sealing lips 17, 18. 
FIG. 1 depicts a seal 1, which is made completely of an elastomeric 
material, in which case seal 1 seals off four intake pipes 5.1, 5.2, 5.3, 
5.4 (FIG. 5), arranged in series, from the cylinder head. The two inner 
sealing surfaces 4.2, 4.3 are interconnected with dimensional stability by 
web segments 6, while the two outer sealing surfaces 4.1, 4.4 are affixed 
by way of a linear tolerance compensation segment 7 to the adjacent, inner 
sealing surface 4.2, 4.3. In the design shown in FIG. 1, it proves to be 
advantageous when the linear tolerance compensation segment 7 is 
reinforced, so that the seal 1 is designed to be substantially 
dimensionally stable and, as a result, can be easily assembled. A 
fiberglass-reinforced plastic can be used as a reinforcement, for example, 
in the linear tolerance compensation segment 7. A sealing action is not 
needed in the area of the linear tolerance compensation segment 7. The 
middle web segment 8, which is designed as a sealing bridge 16, has three 
perforations 14 which form a connection in this exemplified embodiment. 
One end of the connection is joined to the crankcase ventilation opening 
of the internal combustion engine (not shown), while the other end of the 
connection is joined to at least one intake opening of the internal 
combustion engine. By configuring the seal 1 near the cylinder head and by 
designing the intake manifold 2 accordingly, crankcase gas can be 
conducted, as needed, through preheated lines, so that there is no danger 
of icing, nor of damage to the crankcase due to excessive pressure. In 
this exemplified embodiment, the positioning projections 12 have an oval 
shape and can be forced to engage with recesses 13 (FIG. 5) in the intake 
flange 3. 
FIG. 2 shows a seal support 9, in which the web segments that interconnect 
the sealing surfaces 4 are also linear tolerance compensation segments 7. 
In each case, the seal support 9 has a profile that opens out in a U-shape 
in the direction of the two adjoining component parts, so that the 
elastomeric material 15 is located in the depression of the U-shaped 
profile. The elastomeric material 15 engages openings 19 in the seal 
support 9 and is retained to the seal support via form locking. 
On the side opposite the linear tolerance compensation segment 7, the seal 
support 9 is provided with a perforation 20, which is bridged over during 
the normal operational use of the elastomeric material 15, as described 
below. 
In FIG. 3, the sealing part of elastomeric material 15 in accordance with 
FIG. 4 is shown, in which case the sealing surfaces 4.1, 4.2, 4.3, 4.4 
surrounding the intake pipes 5.1, 5.2, 5.3, 5.4 in the area of the flange 
3 are each connected by flexible, elastic web segments 6 to blend into one 
another in one piece. The web segments 6 bridge over perforations 20 of 
the seal support 9 in accordance with FIG. 2. 
FIG. 4 depicts the final assembled seal 1, in which case the linear 
compensation is produced on the one hand by means of the undulated 
tolerance compensation 7 of the seal support 9 and, on the other hand, in 
the opposite partial area by means of a recess in the seal support 9, 
which is penetrated by the elastomeric material 15 of the seal 1. A seal 
developed in such a manner has excellent dimensional stability and can be 
easily manipulated. 
FIG. 5 illustrates an example of an intake manifold 2 that is provided with 
a flange 3. The intake pipes 5.1, 5.2, 5.3, 5.4 are each provided on the 
side of the flange 3 facing the cylinder head with a circumferential 
recess 13, into which the positioning projections 12 of the seal 1 are 
able to be snapped. The preassembled unit is then bolted to the cylinder 
head.