EP1402155B1 - Recycling circuit for crankcase gases on an internal combustion engine - Google Patents

Abstract

A recycling circuit for crankcase gases from an internal combustion engine having an intake manifold with a throttling valve assembly and a cylinder head cover, in which a valve facilitates at least partial control of the flow of crankcase gases to be recirculated. The valve includes a spring and a diaphragm which divides the valve into two distinct chambers, one communicating with the atmosphere and the other communicating with the intake manifold, located downstream of the valve assembly, with a crankcase gas sampler, in which the chamber in communication with the manifold and with the crankcase gas sampler is integrated in the intake manifold and/or the cylinder head cover such that the membrane assures sealing of a part of the manifold or the cylinder head cover from the atmosphere.

Description

The present invention relates to a rebreathing circuit of the crankcase gases of an internal combustion engine.

In internal combustion engines, the lack of tightness between the combustion chamber and the casing causes the latter to progressively fill with leakage gas or crankcase gas, which must be evacuated to prevent a rise in pressure. Formerly, these gases were directly released to the atmosphere but a growing concern for the environment has since led to the development of circuits for the re-aspiration of these gases, that is to say for their reintroduction to combustion, in the engine. .

Thus, in the techniques of the engineer ( Volume BL2 - Mechanical Engineering - Alternative Internal Combustion Engines Technology - B 2800 by Christian Clos - 1996 Edition ), it is recommended the use of two recirculation circuits: a primary circuit, which connects the stitching of the crankcase gases to the air intake pipe downstream of the throttle, and which operates mainly at low speed, when the throttle valve is (almost) closed; and a secondary circuit, which connects the stitching of the crankcase gases to the air filter, and which operates mainly at high speed, when the throttle is open. To avoid excessive vacuum in the sump, which would lead to oil suction, a vacuum limiter (diaphragm valve) can be placed on the primary circuit. However, this way of proceeding involves a large number of parts and fittings and its design is not optimized according to a given engine.

The patent application EP 724206 proposes an improved circuit comprising a diaphragm valve provided with a mouthpiece that can be connected to the stitching of the casing gases and another mouthpiece that can be mounted directly on the intake manifold. Such a circuit always involves fixing a separate part on the collector during assembly of the vehicle, with the risk of leakage resulting therefrom. In addition, it is relatively heavy and expensive and is not further optimized for a given engine, the valve being a standard valve with a wide range of use.

Internal combustion engine with a crankcase gas evacuation valve (10) and a valve body (14, 16), a gas inlet duct (32) connected with the interior space of the crankcase (12), an gas vent (28) connected to an air intake duct of the internal combustion engine and a diaphragm (18) which divides the valve body (14,16) into a chamber (22,24) located inside with respect to the housing (12) and another located outside and has a gas re-aspiration valve head (34), the diaphragm (18) provided with the gas re-suction valve head (34). ) alternately opening the gas evacuation pipe (28) as a function of the pressure difference between the two chambers (22, 24), characterized in that the outer chamber (24) of the valve body (14, 16) ) is connected with the gas supply duct (32) and a ventilation duct (26) arranged in the direction of the casing is also provided, which is elie the inner chamber (22) of the valve body (14, 16) with a surrounding pressure.

The subject of the present invention is therefore a circuit for re-sucking the crankcase gases of an internal combustion engine, which minimizes the number of parts to be assembled during assembly of the vehicle, thus also minimizing the risk of leaks, and of which it is easy to optimize the design according to a given engine.

The present invention therefore relates to a rebreathing circuit of the crankcase gases of an internal combustion engine equipped with an intake manifold provided with a throttle body and a cylinder head cover, in which a valve makes it possible to regulate at least in part the rate of re-suction of the crankcase gases, said valve comprising a spring and a membrane which divides the valve into two separate compartments, one communicating with the atmosphere and the other with the downstream intake manifold of the throttle body and with a crankcase gas tapping, characterized in that the compartment communicating with the manifold and with the crankcase gas tapping is integrated with the intake manifold and / or the cylinder head cover, and that the membrane makes it possible to seal a portion of the collector and / or the head cover towards the atmosphere and that a ventilation hole is in the housing.

An internal combustion engine is understood to mean an internal combustion engine comprising at least one cylinder in which a reciprocating piston which is converted into rotational movement by means of a crank-rod circuit and in which Chemical energy from burning a fuel is transformed into kinetic rotational energy of a tree. The present invention applies to any type of internal combustion engine, but preferably to vehicle engines and in particular gasoline motor vehicles which comprise an intake manifold provided with a throttle body whose purpose is to regulate the supply of combustion air to the engine cylinder. These engines are also equipped with a crankcase that includes the lubricating oil and a cylinder head cover that covers the engine cylinder head (where the oil is injected) and that seals and a thermal insulation and phonic with respect to the outside. The housing and the cylinder head cover generally communicate with each other and constitute a circuit in which the crankcase gases circulate.

According to the invention, these gases are taken in the circuit casing / cylinder head cover by means of a stitching generally carried out at its upper part.

The valve which regulates the rate of re-suction of the crankcase gases according to the present invention is a diaphragm valve, that is to say that it comprises a membrane and a spring whose relative movement leads either to the opening or shutting a communication between the stitching of the crankcase gases and the collector. The membrane divides the valve into two compartments: one communicating with the atmosphere, and the other with the intake manifold and the crankcase venting. According to the invention, the membrane is also used to ensure the sealing of a portion of the collector and / or the cylinder head cover to the atmosphere and in doing so, saves material (the wall of the collector and / or the cylinder head cover being interrupted at this point).

The present invention advantageously makes it possible to eliminate the secondary rebreathing circuit by means of adequate sizing, which will be detailed hereinafter. In this case, the entire re-suction flow rate is regulated by the valve described above.

According to a first variant of the present invention, illustrated in a nonlimiting manner in Figure 1, the collector (1) and the cylinder head cover (not shown) are separate parts and the valve is integrated in the collector. In this case, the compartment (2) communicating with the manifold (1) and the stitching of the crankcase gases (not shown) via a connecting pipe (3) is integrated in the intake manifold, the membrane (4) serving to both to ensure the sealing of the collector and to regulate the re-aspiration flow, together with the spring (5). Indeed, there is constantly balance between the force exerted by the atmospheric pressure of one side of the membrane (compartment 6) and the forces exerted on the other side (compartment (2)) by the depression in the housing, by the depression in the manifold and by the spring. The dimensioning of the elements of this valve (useful diameter of the membrane, displacement of the membrane (function of its rigidity), diameter of the communication orifices, hardness of the spring ...) is optimized according to a given engine to allow its direct integration with the intake manifold. Such optimization (engine bench for example) makes it possible to greatly reduce the size of the membrane and to ensure good regulation for all operating points of the engine. Regarding the gain of material and number of parts, it will be seen that the circuit according to this variant of the invention is reduced to the essential: it essentially comprises a diaphragm / spring pair, a housing (7), a coupling to the stitching of the crankcase gases (3) and fastening means (such as clamps) of this connection respectively on the valve and on the stitching (not shown). The housing (7) can be fixed in any suitable manner on the manifold, for example by clipping or welding. Advantageously, in order to avoid the wear of the membrane and thus, once again, to optimize its dimensions, the membrane may comprise a reinforcement (8) at its center, where it comes into contact with the orifice to the manifold (9), this orifice being in fact generally the end of a manifold. The reinforcement may be an insert, preferably made of a more rigid material than that constituting the membrane.

According to a second variant of the present invention, the manifold and the cylinder head cover are also separate parts, but the valve is this time integrated into the cylinder head cover. In this case, the volume (1) of Figure 1 is the volume between the cylinder head and the cylinder head cover, and the connector (3) this time connects the valve to the collector, all other things being equivalent to those according to the first variant described.

According to a third, preferred variant of the present invention, the intake manifold and the cylinder head cover are integrated, that is to say that they comprise at least one common wall. This variant, illustrated in a nonlimiting manner in FIG. 2, makes it possible to further reduce the number of parts compared with the other variants, since it makes it possible to save the connection either towards the stitching of the crankcase gases (variant 1) or towards the collector (variant 2) and the fastening means of this connection. Indeed, it is sufficient to position the saddle valve on the manifold and on the cylinder head cover and to allow direct tapping of the crankcase gases under the cylinder head cover, via a hole (10) in the lower part of the housing (7). ) located under the cylinder head cover. In Figure 2, (1) represents the internal volume of the intake manifold and (1 ') represents the volume between the cylinder head and the cylinder head cover. Such a fully integrated circuit (collector, cylinder head cover and rebreathing circuit) has only one element to fix during assembly of the vehicle and as it is optimized according to each type of engine, it reduces to the maximum releases to the atmosphere while reducing the weight and size of parts.

The constituent materials of the circuit elements according to the invention are chosen according to their weight, their mechanical strength and their workability, according to their function and design. Thus, in particular to reduce the weight of the assembly and facilitate its realization, it may be advantageous to choose plastic materials as soon as possible, that is to say for most parts, except perhaps be spring loaded and clamps. For example, the membrane and the connection to the quilting are preferably based on an elastomer (such as a silicone, fluoro-silicone or acrylic modified (ACM) rubber), and preferably, a fluoroelastomer if the environment requires it; Clamps and spring are often made of an environmentally resistant metal under the bonnet and salty mists; and the valve housing is advantageously based on a thermoplastic material such as a polyamide or a polyolefin, but preferably a polyamide. This plastic is preferably reinforced by means of a filler such as glass fibers. The The casing is generally made by molding, the injection molding being particularly suitable.

The present invention also relates to an integrated intake manifold for an internal combustion engine, said manifold integrating the valve of the circuit according to the first variant of the invention.

The present invention furthermore relates to an integrated cylinder head cover for an internal combustion engine, said cylinder head cover incorporating the valve of the circuit according to the second variant of the invention.

The present invention also relates to an integrated intake manifold / cylinder head cover for an internal combustion engine, said manifold / valve cover incorporating the valve of the circuit according to the third variant of the invention.

The present invention also relates to a method for the design of a casing gas rebreathing circuit of an internal combustion engine as described above. This method consists in optimizing the parameters (geometry, materials, etc.) of the valve described above according to the operating parameters of an engine, thanks to the use of an engine bench. By engine bench, is meant to designate a test bench that allows, depending on the characteristic points of the engine (speed and torque function) to impose a crankcase suction flow rate and a vacuum on admission. We then measure the value of the depression at the crankcase and compare the value with that of the specifications of the vehicle manufacturer.

The present invention finally relates to a diaphragm valve for a rebreathing circuit, an intake manifold and / or an integrated cylinder head cover as described above, this valve being preferably mainly made of plastic. By "mainly plastic" is meant that the valve housing is made of plastic material, preferably injection moldable (such as polyamide or polyolefin, optionally filled with glass fibers), and that the The membrane is also made of plastic but preferably of a silicone elastomer or not, optionally fluorinated.

Claims (6)

1. Recycling circuit for the crankcase gases of an internal combustion engine equipped with an intake manifold that is provided with a throttle valve assembly and a cylinder head cover, the said recycling circuit including a valve that enables the flow recycling the crankcase gases to be regulated at least in a partial manner, the said valve including a spring and a diaphragm (4), which divides the valve into two specific compartments, the one communicating with the atmosphere and the other with the intake manifold downstream of the throttle valve assembly and with a crankcase gas tap, and in that the compartment communicating with the manifold and with the crankcase gas tap is integrated in the intake manifold and/or the cylinder head, characterised in that the diaphragm allows a part of manifold and/or the cylinder head to be sealed towards the atmosphere and in that there is a ventilation hole in the housing (7) containing the diaphragm (4).
2. Circuit according to the preceding claim, characterised in that the entire recycling flow is regulatable by the valve.
3. Circuit according to claim 1 or 2, characterised in that the manifold and the cylinder head cover are separate parts and in that the valve is integrated in the manifold.
4. Circuit according to claim 1 or 2, characterised in that the manifold and the cylinder head cover are separate parts and in that the valve is integrated in the cylinder head cover.
5. Circuit according to one of claim 1 or 2, characterised in that the intake manifold and the cylinder head cover include at least one common wall, and in that the valve is positioned astride the manifold and the cylinder head cover so as to allow the crankcase gases to be tapped directly under the cylinder head cover.
6. Integral intake manifold for an internal combustion engine, characterised in that the said intake manifold incorporates the circuit valve according to any one of the claims 1 to 3.

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