Patent Description:
in the truck industry, turbochargers are commonly used with Diesel cycle internal combustion engines. A turbocharger is a turbine-driven device that increases the efficiency and the power of an internal combustion engine by forcing extra air into the combustion chamber. Typically, a turbocharger is powered by a turbine driven by the hot exhaust gas of the engine.

In most of the cases, the turbine is a fixed geometry turbine that includes a flange provided with a dividing wall to separate the flow of exhaust gases in two flows. Typically, considering a six-cylinder manifold, exhaust gases coming from the first three cylinders are separated from exhaust gases coming from the three other cylinders. A comparable flange is provided on the exhaust manifold. The separation of the exhaust gases in two separate flows helps reducing fuel consumption.

Most of the time, the exhaust manifold and the turbine are two different parts, meaning that the connection between the two flanges needs to be sealed. To this end, one uses a gasket, which is often referred to as a sealing gasket. This gasket includes two flow passage openings separated by a dividing wall. In operation, exhaust manifold and turbocharger dividing walls are subjected to high temperatures, in particular when a stabilized phase is reached, i.e. after long full load running. The hottest part of exhaust manifold and turbocharger are dividing walls as they are in contact with both hot gas flows circulating through exhaust manifold and turbocharger openings and as it is not in contact with ambient air. The thermal expansion of the dividing walls is then greater than for the rest of flanges, which causes contact pressure between dividing walls. This contact pressure reduces the contact pressure of the gasket on flanges, which may cause leakage issues.

One basic solution to this problem is to delete the dividing wall portion of the gasket between the two openings, making a big large opening in the gasket. However, two disadvantages result from this solution. A first one is that the two flows of exhaust gas may communicate at the interface between the manifold and the turbine, creating losses of pulse energy and increasing full consumption. A second one is that the exhaust manifold and turbo dividing walls are locally hotter, which may cause cracks.

The invention intends to remedy these drawbacks by proposing a new gasket design, with which there is no risk of gas communication at the interface between the manifold and the turbine and with which there is less risk of leakages due to the thermal expansion of dividing walls.

To this end, the invention concerns a sealing gasket, for sealing a connection between an exhaust manifold and a turbine of a vehicle, according to claim <NUM>.

<CIT> discloses an example of a sealing gasket between an exhaust manifold and a turbine. The sealing gasket includes a sealing portion extending around the two openings of the gasket. This sealing portion includes a seal ring housed in a ringshaped groove milled into the sealing gasket. The problem of this gasket is that it does not efficiently prevent gas communication at the interface between the turbine and the manifold.

<CIT> discloses another example of a sealing gasket, which is mounted between a turbo-supercharger and an exhaust manifold of a diesel engine. The gasket is provided with two flow passage openings and with two sealing ribs extending each around a respective opening of the gasket. The problem of this gasket is that it does not efficiently prevent gas leakages.

Other similar sealing gaskets are disclosed in <CIT> and <CIT>.

Thanks to the invention, the first sealing portion extending around the two openings enables avoiding as far as possible the gas leakages due to the thermal deformation of exhaust manifold and turbocharger flanges and the second sealing portion enables avoiding as far as possible the two flows of exhaust gas to communicate at the interface between the turbine and the manifold. In other words, the sealing functions of the gasket are enhanced in comparison with prior art sealing gaskets. The first and the second sealing portion are designed to compensate different deformation.

Further advantageous features of the gasket are defined below:.

The invention also concerns an internal combustion engine comprising an exhaust manifold, a turbine, and a sealing gasket as previously defined, sealing the connection between the turbine and the manifold.

The invention also concerns a vehicle, such as a truck or a tractor truck, comprising an internal combustion engine as defined above.

The invention will be better understood from reading the following description, given solely by way of two non-limiting examples and with reference to the appended drawings, which are schematic depictions, in which:.

<FIG> represents, in side view, a vehicle which is, in the example, a tractor truck <NUM>. However, in a non-represented alternative embodiment, the vehicle may be different from a tractor truck. For instance, the vehicle may be a light, medium or heavy-duty vehicle, a utility vehicle, an autonomous vehicle, etc..

The tractor truck <NUM> includes an internal combustion engine comprising an engine block (not represented) including a plurality of combustion cylinders, typically six cylinders.

The engine further includes an exhaust gas manifold <NUM>, represented on <FIG>, which collects the gas exhausting from the combustion chambers of the engine cylinders. Typically, the exhaust gas manifold <NUM> includes six inlets <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> to be respectively connected to the combustion chambers of the engine. Exhaust gases coming from the first three cylinders, i.e. flowing in the inlets <NUM> to <NUM>, are separated from exhaust gases coming from the three other cylinders, i.e. flowing in the inlets <NUM> to <NUM>. Accordingly, the manifold <NUM> includes two gas flow channels <NUM> and <NUM> that open on a connecting flange <NUM> of the manifold <NUM>. Both gas flow channels <NUM> and <NUM> are separated by a dividing wall <NUM> of the manifold <NUM>. The dividing wall <NUM> extends up to the connecting flange <NUM>.

The engine also includes a turbocharger <NUM> (cf. <FIG>) comprising a compressor part <NUM> and turbine part <NUM> that can be, for instance, a fixed geometry turbine (FGT). Turbine <NUM> converts the thermal and kinetic energies of the exhaust gases into a mechanical torque. Typically, the generated mechanical torque may be used to power the compressor part <NUM>. According to an alternative of the invention that is not represented, the turbine <NUM> is not necessary part of a turbocharger and can be used to power another vehicle equipment such as, for instance, a pump. The turbine <NUM> includes two inlets gas flow channels <NUM> and <NUM>, to be connected respectively with the two gas flow channels <NUM> and <NUM> of the exhaust gas manifold <NUM> via a connecting flange <NUM> of the turbine <NUM> and the connecting flange <NUM> of the manifold <NUM>.

Both inlets gas flow channels <NUM> and <NUM> open on the connecting flange <NUM>. The connecting flange <NUM> is provided with a dividing wall <NUM> to separate the inlets of the gas flow channels <NUM> and <NUM> and to therefore separate the flow of exhaust gases in two flows. A gasket <NUM>, represented on <FIG>, is used for sealing the connection between the flange <NUM> of the turbine and the flange <NUM> of the manifold <NUM>. The gasket <NUM> is in the form of the turbine flange <NUM> and is made of a single steel layer.

The gasket <NUM> comprises two flow passage openings <NUM> and <NUM> separated by a dividing wall <NUM> corresponding to the dividing walls <NUM> and <NUM>, respectively of the manifold <NUM> and of the turbine <NUM>.

Preferably, there are only two flow passage openings. In the example, the two openings are of rectangular shape. However, any other shape is possible. Typically, the openings <NUM> and <NUM> may be of circular shape.

Advantageously, the gasket <NUM> delimits holes <NUM> for the passage of fixing bolts (not represented).

The gasket <NUM> includes a first sealing portion <NUM>, represented schematically with broken lines, extending around the two openings <NUM> and <NUM>. Preferably, the sealing portion <NUM> is a sealing bead that is integral with the rest of the gasket. In particular, this sealing bead forms a rectangle surrounding the openings <NUM> and <NUM>.

The sealing gasket comprises also a second sealing portion <NUM>, represented schematically with broken lines, extending around the opening <NUM>. The sealing gasket may comprise a third sealing portion <NUM>, also represented schematically with broken lines, extending around the opening <NUM>. Preferably, the sealing portions <NUM> and <NUM> are two distant sealing beads that are integral with the rest of the gasket <NUM>. in particular, each sealing bead forms a rectangle surrounding the opening <NUM> or <NUM>. Alternatively, the sealing portions <NUM>, <NUM> and <NUM> may be of different shape. Typically, the sealing portions <NUM>, <NUM> and <NUM> may be of circular shape.

Advantageously, sealing portions <NUM> and <NUM> are surrounded by the sealing portion <NUM>.

Given that the sealing beads <NUM>, <NUM> and <NUM> are integral with the rest of the gasket <NUM>, the gasket <NUM> may be easily manufactured in one-piece, for example by stamping.

According to claim <NUM>, the gasket is made of a single steel layer.

On <FIG>, arrows F2 represent the direction of the two respective gas flows coming from the manifold <NUM> and entering into the turbine <NUM>. As shown on this figure, in assembled state, the channel <NUM> communicates in a gas-tight manner with channel <NUM> and channel <NUM> communicates in a gas-tight manner with channel <NUM>.

For the clarity of the drawing, the gasket <NUM> is represented on <FIG> but the sealing beads are not represented.

Preferably, the first sealing portion <NUM> and the second sealing portion <NUM> are designed differently, to compensate different deformation. When the sealing gasket <NUM> comprises a further third sealing portion <NUM>, the first sealing portion <NUM> on the one hand and the second and the third sealing portions <NUM>, <NUM> on the other hand are designed differently to compensate different deformation.

According to an improvement of the sealing gasket <NUM>, the first sealing portion <NUM> has a height H1 (<FIG>) measured over the thickness of the plate and when it is in a rest state , that is to say in non-compressed state, that is higher than the height H2 of the second sealing portion <NUM>. When the sealing gasket <NUM> comprises a further third sealing portion <NUM>, the first sealing portion <NUM> has a height H1, measured over the thickness of the plate, (when it is not compressed) that is higher than the heights H2, H3 of the second and third sealing portions <NUM>, <NUM>.

Owing to this, the thermal expansion of the dividing walls <NUM> and <NUM>, that is greater than for the rest of the flanges <NUM>, <NUM>, is compensated by the provision on the gasket <NUM> of a first sealing portion <NUM> having a height H1 (<FIG>) measured over the thickness of the plate that is higher than the heights H2, H3 of the second and third sealing portions <NUM><NUM>. Thanks to that, when the sealing gasket <NUM> is mounted on an engine and the engine is running, the contact pressure of the gasket <NUM> between the flange <NUM> and the flange <NUM> is maintained in the peripheral zone of the flanges that extends around the two openings <NUM> and <NUM> even when the dividing walls <NUM> and <NUM> have a greater thermal expansion than the rest of the flanges <NUM>, <NUM>. Consequently, leakage issues can be avoided in this peripheral zone even when the dividing walls <NUM> and <NUM> have a greater thermal expansion than the rest of the flanges <NUM>, <NUM>.

Preferably, the first sealing portion <NUM> has a height H1, measured over the thickness of the plate, that is at least <NUM>% higher than the height H2 of the second sealing portion <NUM>. When the sealing gasket <NUM> comprises a further third sealing portion <NUM>, the first sealing portion <NUM> has a height H1, measured over the thickness of the plate, that is at least <NUM>% higher than the heights H2, H3 of the second and third sealing portions <NUM>, <NUM>. For instance, the first sealing portion <NUM> may have a height H1 that is comprised between <NUM> and <NUM> and the second sealing portion <NUM> and/or the third sealing portion <NUM> may have a height H2, H3 that is comprised between <NUM>,<NUM> and <NUM>.

Preferably, the second sealing portion <NUM> and the third sealing portion <NUM> are designed to compensate amplitudes of the thermal deformations of the dividing walls <NUM> and <NUM>.

Preferably, the height of the first sealing portion <NUM> is determined such that in a compressed state of the first sealing portion <NUM>, the height h1 of the first sealing portion <NUM> (measured over the thickness of the sealing gasket <NUM>) is equal to the height h2 or h3 of the second or third sealing portion <NUM> or <NUM> when compressed plus a height HA corresponding to the maximum amplitude A of deformation of the second or third sealing portion <NUM> or <NUM> at the dividing wall <NUM> such as met under operating conditions, that is to say when the sealing gasket <NUM> is mounted on the engine. Under operating conditions, the amplitude A of deformation of the second or third sealing portion <NUM> or <NUM> at the dividing <NUM> is mainly caused by the thermal deformation of the dividing walls <NUM> and <NUM>. Preferably, said amplitude A caused by thermal deformations of the dividing walls <NUM> and <NUM> is measured between ambient temperature of the exhaust manifold <NUM> when the engine is stop or just started and high temperatures of the exhaust manifold <NUM> met during some operations of the engine. The amplitude A is measured according to a direction that is perpendicular to the sealing gasket main surface.

The two sealing beads <NUM> and <NUM> are preferably not merged in the region of the dividing wall <NUM>, meaning that there is a double sealing between the two openings <NUM> and <NUM> of the gasket <NUM>. Accordingly to this improved arrangement, the gasket <NUM> according to the invention provides an improved sealing between the two gasket openings <NUM>, <NUM>, i.e. in the region of the dividing wall <NUM>.

Preferably, sealing portions <NUM>, <NUM> and <NUM> are provided on both sides of the sealing gasket <NUM>, meaning that a first group of three sealing portions are designed for being in sealing contact with the manifold flange <NUM> on one side of the gasket <NUM> and that a second group of three identical sealing portions are designed for being in sealing contact with the turbine flange <NUM> on the other side of the gasket <NUM>.

Alternatively, and as shown on <FIG>, the gasket <NUM> may include only two sealing portions <NUM> and <NUM>, i.e. two sealing beads. In other words, the sealing portion <NUM> (or <NUM>) is purely optional.

Claim 1:
Sealing gasket (<NUM>), for sealing a connection between an exhaust manifold (<NUM>) and a turbine (<NUM>) of a vehicle (<NUM>), the sealing gasket comprising two flow passage openings (<NUM>, <NUM>) separated by a dividing wall (<NUM>) and a first sealing portion (<NUM>) extending around the two openings, in which the sealing gasket comprises at least a second sealing portion (<NUM>) extending around one (<NUM>) of the two openings, and a third sealing portion (<NUM>) extending around the other (<NUM>) of the two openings, each sealing portion (<NUM>, <NUM>, <NUM>) is a sealing bead, that is integral with the rest of the gasket, in which the sealing gasket (<NUM>) is in the form of a plate and sealing portions (<NUM>, <NUM>, <NUM>) protrude at least on one side of the plate, characterized in that the sealing gasket (<NUM>) is made of a single steel layer, and in that the first sealing portion (<NUM>) has a height (H1), measured over the thickness of the sealing gasket (<NUM>), that is at least <NUM>% higher than the heights (H2, H3) of the second and third sealing portions (<NUM>, <NUM>).