EP1484480A1 - Flexible liner for oil sump - Google Patents

Abstract

The case has a compartment (14) mounted on an internal combustion engine (10). The compartment has a tank (22) and a peripheral strap (24) with screws and holes. A flexible inner liner (16) has a profile conforming to that of the compartment. A groove in an inner side of the strap receives a thick free edge of the liner. The screws and rings are acoustically insulated at the side of the compartment.

Description

The present invention relates to a flexible liner casing forming a cover or casing, especially usable as an oil pan or as a cylinder head cover for internal combustion engines.

In internal combustion engines of vehicles, especially cars and trucks, an oil circuit is provided for the lubrication of the engine. A pump linked to the engine speed ensures the pressurization and circulation oil. This pump sucks directly from a casing which constitutes the tarpaulin.

This casing is necessarily placed at the lowest point for gravity recovery oil so that it is located under the engine block. For most of them, the casing is not an integral part of the engine block and it is attached below.

It is immediately understood that this casing is vulnerable to obstacles from the road and it is at the ground clearance limit since the engine in its set is usually positioned as low as possible, for reasons obvious lowering of the center of gravity. So this housing must has a resistance adapted to statistically probable shocks.

The oil in circulation is at a temperature of the order of a hundred degrees Celsius and the housing that contains it must not only resist it but must also present only the most limited possible deformations, in particular hot, which implies a certain mechanical resistance.

Given the ever-increasing performance of the engines, the lubrication is playing an increasingly important role so that even for small displacement engines, the volume of oil in circulation is necessarily important so that the volume of the housing is important. This is proportional and for truck engines, we understand that the crankcase volumes are very important.

A special feature of these oil sumps is still the presence of a plug of draining in the lower part of said casing in order to empty it completely for change the oil, even if the tendency is to space out the oil changes thanks to changes in oil quality and advances in engine design themselves.

It is necessary to note at this stage of the presentation of the prior art that for engines and for vehicles in general, hunting for weight is a constant concern of manufacturers.

For these reasons, the current casings are made either of thin sheet metal form by stamping, either in aluminum foundry or in materials composites. A flange is provided at the periphery of the casing to allow a fixing on the engine block, a seal being interposed between the two to sealing. This flange protrudes outward to allow the screwing of the screws which ensures the fixing.

This arrangement leads to the installation of casings which have another significant disadvantage, that of generating noise or at least of amplify, especially those from the engine block, forming a sound box. Indeed, to ensure a suitable seal, including in temperature and to provide a perfect connection to the engine block, the fixing points are numerous, evenly distributed along the peripheral flange.

By this significant tightening, the seal, even when made of elastomer, presents a certain stiffness which prohibits the elimination of certain noises, more especially in the low frequencies, while these are the most harmful more disturbing. Amortization likely to be provided by the barrier elastomer disappears.

To limit this noise, it is necessary to ensure a sound decoupling of the casing and of the engine block, while ensuring suitable fixing.

This is how we know a European patent application EP 1 239 125 which ensures the desired decoupling by providing a first metal flange secured to the engine block by screwing, a second metal flange from manufacturing with the casing and also fixed to the engine block by the same screws spacer with elastic washers for breaking vibration bridges, and a elastomer seal interposed between the first and second flanges, thereby ensuring sealing. The seal is directly attached to the two flanges by overmolding but this step remains industrially delicate.

Furthermore, the main drawback of this solution is that it only works for high frequencies, since the seal must provide a compromise between sealing with high stiffness and decoupling with low stiffness.

Therefore, other solutions are sought, which leads to the content of the present invention.

The Applicant also made an interesting finding regarding the cylinder head cover in internal combustion engines. Indeed, this piece technique has exactly the same constraints as oil sumps. This part is of complex shape, it must have mechanical resistance sufficient in particular to allow the return of organs such as a internal oil separator and / or external hoses or fixing lugs.

Sealing must be guaranteed, the fluid is identical since it is the same engine oil and temperatures are also the same.

Similarly, the drain plug is of course no longer necessary but the plug oil filling is located on this cylinder head cover and substantially imposes the same constraints as the drain plug.

Noise pollution caused by mechanical parts in operation in this closed volume and / or emitted by the cylinder head and the engine block are amplified, contributing to the discomfort of passengers of vehicles using such engines.

The solution provided by the present invention finds an application both for oil sumps only for cylinder head covers in internal combustion engines internal.

To this end, the casing according to the invention, in particular for an internal combustion engine internal, includes an enclosure intended to be attached directly or indirectly on said motor, and is characterized in that it comprises a liner interior, flexible, preferably in profile combined with that of said enclosure.

This enclosure comprises a tank and at least one peripheral flange provided with means of fixing to the engine as well as means of fixing the liner interior, flexible.

The means for fixing the flange to the motor include threads engine side and holes, screws and washers of which at least one is acoustically insulating, enclosure side, these screws screwing into the threads so as to take up only the mechanical forces.

As for the means for fixing the flexible inner liner, they comprise at least a groove in the flange, on the inner side, designed to receive a thick profile formed on the free edge of the liner, with a cross-section of that of this throat.

According to an improvement, the liner comprises peripheral bellows.

According to an alternative embodiment, the embodiment realization flange is double with two parts offset from the tank beyond the bulk motor, fixing screws on the motor and connecting screws of the two parts of said double flange.

In addition, the housing includes an opening with a hole threaded fitted with a shoulder, an annular lip, coming from manufacturing with the liner and a plug to close this tapped hole.

According to another variant, the casing comprises a tranquilizer arranged at inside the volume defined by the liner.

This tranquilizer advantageously comprises walls substantially parallel to those of the enclosure with edges inclined inward.

• figure 1, une vue en perspective éclatée d'un carter d'huile moteur selon l'invention,
• figure 2A, une vue en coupe transversale du carter avant montage, et
• figure 2B, une vue en coupe transversale du carter après montage,
• figure 3, une variante de réalisation avec extension de volume, et
• figure 4, une vue de détail de réalisation d'une ouverture.

The invention is now described in detail according to a particular, non-limiting embodiment, with regard to a set of drawings in which the different figures represent:

• FIG. 1, an exploded perspective view of an engine oil pan according to the invention,
• FIG. 2A, a cross-sectional view of the casing before mounting, and
• FIG. 2B, a cross-sectional view of the casing after assembly,
• FIG. 3, an alternative embodiment with volume extension, and
• Figure 4, a detail view of an opening.

The description which follows and the associated drawings relate to an oil pan. of an internal combustion engine but would find a direct application for the realization of a cylinder head cover, only the shapes and the connections being different by their geometries and their locations.

In FIG. 1, the engine block concerned is referenced 10 while the casing 12 according to the invention comprises at least two elements, an enclosure 14 and a liner 16 interior, flexible profile combined with that of the enclosure.

The engine block in a known manner comprises threads 18 ready to receive screws 20.

The enclosure 14 has sufficient mechanical strength to support mechanically the contents of the sump, namely the oil. Preferably, the resistance mechanical also allows it to undergo defined shocks, in particular projection stones at a given speed. Rigid plastic is sufficient in the context of the invention and the use of metals is not a necessity. Of even, the use of composites is not required since, as described below, the enclosure is not in direct contact with the contents of the housing.

This enclosure has a particular structure which is visible in the figures 2A and 2B.

Indeed, there is provided a tank 22 surmounted by a peripheral flange 24, in the occurrence, a flange coming from molding with said tank according to a first variant. This flange projects outward from the tank.

Holes 26 are provided on this flange for the passage of the screws 20.

On the inner side of the flange, there is provided a groove 28 adapted to receive the liner 16 as will be explained later.

In addition, a rigid washer 30 and an elastomer washer 32 compressible are arranged on either side of the flange to ensure a suitable mechanical assembly with effective clamping and sound insulation.

The liner 16 is made of at least one elastomer material resistant to oil and the temperature to which the oil is subjected. This elastomer must also have excellent resistance to aging.

Preferably, the liner is shaped so as to match the shape of the tank 22 enclosure 14.

Its free edge has a thick profile 34, combined with that of the groove 28, so as to be able to enter it in force and remain blocked there. Note that this profile 34 thick protrudes at the top, especially in Figure 2A, before mounting and tightening.

This liner can be fitted with 36 peripheral bellows facilitating mounting and installation in the enclosure while allowing a conformation adapted to the volume of the tank which receives it, without thereby causing deformations of the elastomer itself.

In Figure 2B, we can see the deployment of these bellows when the fluid 38, in this case oil, is introduced into the casing.

When the screws are tight, we also note the crushing of the thick edge of the liner against the engine block, crushing which seals at the interface.

The tightening does not need to be high because, the elastomer reach being low, the pressure at the right of this sealing barrier is high.

The elastomer along this barrier is clamped and its stiffness is high but it there is no transmission or at least a strong attenuation because the walls of the liner dampen the vibrations generated in the free volume it contains, whatever frequency, including low frequencies.

There is a dissociation of functions, the resumption of mechanical forces guaranteed by enclosure 14 and the sealing function provided by liner 16.

From an industrial production point of view, the two parts are easily manufactured and especially quickly pre-assembled.

Another advantage is that it requires a reduced number of clamping points therefore a reduced number of screws. This also induces blind holes in number also reduced on the engine block hence a substantial saving.

Such a housing keeps the seal even if the enclosure of the housing is deteriorated following a shock. Indeed, in the event of a reasonable shock, the enclosure 14 can be split but the flexible liner remains intact so that there is no interruption of operation of the engine equipped with the casing according to the invention.

Likewise, the material can be chosen from less noble materials and therefore very low cost since the required technical characteristics are lesser, notably resistance to aging, resistance to temperature and in contact with hydrocarbons since these constraints are transferred to the liner.

A variant of the invention shown in Figure 3 provides advantages additional.

Indeed, the flange 24 is actually double and comprises two parts 24-1 and 24-2.

Depending on the shape given to each of the parts, one can thus ensure an offset of the tank beyond the motor size while allowing access to the screws 20-1 for fixing to the engine block and to the screws 20-2 for connecting the two parts.

After removing the screws 20-2, you can access the screws 20-1 by moving the liner, even if it contains fluid.

As the 20-2 screws provide mechanical support, the number of screw is reduced because there is no sealing function to ensure. As for example, the tank 22 is fixed by means of flexible type fasteners "washers" and / or interposing between the tank 22 and the part of the flange 24-1 elastomer washers.

This offset first leads to increasing the volume of fluid 38 available, without however increase the depth which would result in a decrease in ground clearance.

As another advantage, we see that the replacement of the enclosure is very fast since it suffices to remove the screws 20-2 and reassemble a new one enclosure without removing the screws 20-1 and therefore without affecting the seal. he there is also no need to drain the fluid there.

According to another characteristic of this variant, the flange 24-1 and the liner can be in one piece, obtained by adhesion on the link flange elastomer for example.

Furthermore, it is noted according to the variant of Figure 3 that the tank 22 is not attached directly to the engine block, as for the variant in the figure 2A, but indirectly.

In this case, the decoupling is optimized because the tank 22 is simply suspended to a flange itself linked to the engine block, the liner ensuring the function sealing.

To drain the fluid, it is necessary to provide an opening 40 even if draining means can be provided by suction.

This opening, shown in FIG. 4, comprises a tapped hole 42, of preferably molded with the bottom of the tank 22. This tapped hole is provided a shoulder 44 on which is housed an annular lip 46, coming from molding with the liner 16.

A plug 48 makes it possible to close the tapped hole.

It can be seen that such an arrangement makes it possible to overcome the presence of a independent seal, since the elastomer lip 46 taken between the shoulder 44 and the plug 48 contributes to sealing.

According to an improvement of the invention, it is possible to add a tranquilizer 50 in the volume defined by the liner. Such a tranquilizer consists of walls 52 substantially parallel to those of the enclosure with edges 54 inclined towards the interior, as shown in FIGS. 1 and 2A, in phantom.

This tranquilizer is advantageously fixed to the enclosure, through the liner, of preferably on the bottom, to the right of the opening 40.

Such a tranquilizer avoids excessive fluid movements during acceleration, braking or cornering movements.

According to another characteristic of the invention, the outer surface of the liner may include protruding elements, for example grooves, in order to provide an air gap between said liner and the tank helping to improve sound and thermal insulation.

Furthermore, according to the invention, it is possible to provide between the tank 22 and the liner 16, temperature, oil level or other sensors, these different elements and their connections being protected by the tank 22.

Claims (9)

Housing (12) in particular for an internal combustion engine (10), comprising an enclosure (14) intended to be attached to said engine, characterized in that it comprises an inner liner (16), flexible, preferably of conjugate profile of that of said enclosure. Housing (12) according to claim 1, characterized in that the enclosure (14) comprises a tank (22) and at least one peripheral flange (24) provided with means (20, 26) for fixing to the motor (10) as well as means (28, 34) for fixing the flexible inner liner (16). Housing (12) according to claim 2, characterized in that the means for fixing the flange (24) on the motor (10) comprise internal threads on the motor side and holes (26), screws (20) and washers (30, 32) of which at least one is acoustically insulating, on the enclosure side, these screws (20) screwing into the threads so as to take up only the mechanical forces. Housing (12) according to claim 2 or 3, characterized in that the means (28, 34) for fixing the inner liner (16), flexible, comprise at least one groove (28) formed in the flange, on the inner side, designed to receive a thick profile (34) formed on the free edge of the liner (16), of cross section conjugate with that of this groove. Housing (12) according to any one of the preceding claims, characterized in that the liner (16) comprises peripheral bellows (36). Housing (12) according to any one of claims 2 to 5, characterized in that the flange (24) is double with two parts (24-1, 24-2) offset from the tank (22) beyond the size of the engine, screws (20-1) for fixing to the engine and screws (20-2) for connecting the two parts of said double flange. Housing (12) according to any one of the preceding claims, characterized in that it comprises an opening (40) with a tapped hole (42) provided with a shoulder (44), an annular lip (46), coming from manufacturing with the liner (16) as well as a plug (48) making it possible to close this tapped hole. Housing (12) according to any one of the preceding claims, characterized in that it comprises a tranquilizer (50) arranged inside the volume defined by the liner (16). Housing (12) according to claim 8, characterized in that the tranquilizer (50) comprises walls (52) substantially parallel to those of the enclosure (14) with flanges (54) inclined inward.

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