FR2973071A1 - Oil decanter for separating liquid and gas phases of blow-by gas in e.g. positive-ignition engine, has casing internally defining cooling channel for passage of coolant, where channel is hermetically isolated from decantation chamber - Google Patents

Abstract

The invention relates to a decanter (100) comprising a casing which delimits a settling chamber (110) of gases discharged from an oil sump. According to the invention, the casing also delimits a cooling channel (120) for the passage of coolant, which is hermetically isolated from said settling chamber.

Description

TECHNICAL FIELD TO WHICH THE INVENTION RELATES The present invention relates generally to the separation of the liquid and gaseous phases of the gases contained in the oil sump of an internal combustion engine. It relates more particularly to an oil decanter which comprises a casing delimiting a chamber for decantation of these gases. It also relates to an internal combustion engine comprising: - an engine block provided with a cylinder block, an oil sump located under the cylinder block, and a cylinder head covering the cylinder block, a cooling circuit in which circulates coolant, and - a settling circuit in which circulates gases discharged from the oil sump. BACKGROUND ART In an internal combustion engine of the aforementioned type, the cylinder block has cylinders closed, on the top, by the cylinder head, and, on the bottom, by pistons. The internal volume of each cylinder, which is the place of combustion of the fuel and of the air sucked by the engine, is called the combustion chamber. When the engine is running, most of the flue gas escapes from the combustion chambers through the exhaust line. A small part of these flue gas nevertheless escapes from the combustion chambers to the oil sump, passing between the pistons and the cylinders. These burned gases then mingle with the hot gases contained in the oil sump, increasing their pressure. In order to lubricate all of its members, the engine block further comprises pumps that are adapted to draw hot oil into the oil sump to project on its organs. These projections of oil generate oil particles, vaporized or not, which mingle with the hot gases contained in the oil sump. These gases evacuated from the oil sump, hot, under pressure and loaded with oil are commonly referred to by anglicism "blow-by gas". To ensure the proper functioning of the engine, it is then necessary to separate the liquid and gaseous phases of these gases in order to recover the oil and return it to the oil sump, so that it can continue to exert the lubrication function for which it is intended. It is also necessary to evacuate from the oil sump a portion of these gases in order to reduce the pressure of the gases contained in this sump. For this, the engine includes a decanter in which the gases evacuated from the hottest sump up, condense and then are discharged to the engine air intake. The decanter has for this purpose internal walls which define a labyrinth for gases discharged from the oil sump. The walls of this labyrinth then form so many surfaces on which the oil vapors contained in the gases discharged from the oil sump condense and against which the liquid oil particles are projected. In this way, the decanter makes it possible to recover a portion of the oil contained in the gases evacuated from the oil sump to return it to the sump. The efficiency of a decanter is then measured in part according to its ability to rapidly condense the oil vapors contained in the gases discharged from the oil sump. OBJECT OF THE INVENTION The present invention then proposes a new decanter, whose efficiency is optimized. More particularly, according to the invention, there is provided a decanter as defined in the introduction, wherein the housing also defines a cooling channel for the passage of cooling liquid, which is hermetically isolated from said settling chamber. Thus, thanks to the invention, when the engine is running, the coolant circulates inside the decanter, which makes it possible to cool the walls delimiting the decantation chamber of the decanter. It then follows an acceleration of the condensation rate of the oil vapors, in favor of the efficiency of the decanter. Other advantageous and non-limiting characteristics of the clarifier according to the invention are the following: said cooling channel and said settling chamber extend in length, and said cooling channel runs along said settling chamber; said cooling channel is isolated from said settling chamber by an internal partition of the casing; the casing comprises a junction wall to be applied against a corresponding wall of an engine block, which delimits at least one gas inlet discharged from the oil sump inside said settling chamber and at least one outlet of oil evacuation to the engine block; the casing delimits at least one coolant inlet inside said cooling channel and at least one coolant outlet, which are situated at a distance from said junction wall; and - the housing defines a housing housing a thermostat. The invention also proposes an internal combustion engine as defined in the introduction, which comprises a decanter as mentioned above, the casing of which is fixed to the engine block, the cooling channel of which is connected to the cooling circuit, and the chamber of which decantation is connected to the settling circuit. Other advantageous and non-limiting features of the internal combustion engine according to the invention are as follows: the decanter is fixed on an outer face of the cylinder block; - The cooling circuit comprises a thermostat whose valve is located in the cooling channel of the decanter; and the cooling circuit comprises a water pump having a coolant inlet, and the decanter housing carries a coolant outlet duct which is directly connected to the inlet of the water pump. DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT The following description, with reference to the accompanying drawings, given by way of non-limiting example, will make it clear what the invention consists of and how it can be achieved.

In the accompanying drawings: - Figure 1 is a schematic sectional view of an engine block equipped with a decanter according to the invention; - Figures 2 and 3 are schematic perspective views of the decanter of Figure 1, shown at two different angles; and - Figure 4 is a schematic rear perspective view of the decanter of Figure 1, a rear portion of the housing has been removed to reveal the interior of the decanter. In the description, the terms "upstream" and "downstream" will be used according to the flow directions of the fluids. In Figure 1, there is shown schematically a motor block 2 of an internal combustion engine 1 of the spark ignition type (or "gasoline"). This engine block 2 comprises a cylinder block 3 provided with cylinders 4 in Al axis lines slightly inclined relative to the vertical V1, here four in number, only one of them appears in the figure. This cylinder block 3 is closed on its lower part by an oil sump 5 containing oil for lubricating the various engine components, and on its upper part by a cylinder head 10 which is itself covered with a cylinder head cover 7.

Conventionally, the cylinder 4 houses a piston 8 which is adapted to slide inside thereof in a reciprocating rectilinear motion of Al axis. The piston 8 has a peripheral skirt which is pierced transversely by two openings for receiving an axis 8A. There is also provided a connecting rod 9, one end is linked (by a pivot connection) to this axis 8A and the other end is connected (by an eccentric pivot connection) to a crankshaft 9A. Thus, the reciprocating rectilinear movement of the piston 8 makes it possible to drive the crankshaft 9A of the internal combustion engine 1 in rotation. The cylinder head 10 of the engine block 2, for its part, houses the various engine distribution members, ie that is to say the different organs for supplying fresh air and fuel each cylinder 4. The cylinder head 10 has for this purpose a base 11 of generally parallelepiped shape, having a lower face 12, also called "fire face" to apply against the upper face of the cylinder block 3. This lower face 12 has in particular four recessed portions 13, here conical, located in the extension of the cylinders 4 of the cylinder block 3 and intended to close the upper ends of these four cylinders 4 These four recessed portions form four cylinder heads 13. Each cylinder 4 thus delimits, with the cylinder head 13 and the piston 8 associated therewith s, a combustion chamber 6. For the fresh air intake of each cylinder 4, the base 11 of the cylinder head 10 is pierced with at least one intake duct 20 which extends from an air distributor 16 attached to the cylinder head 10 to the cylinder head 13 associated with the cylinder 4. For the exhaust of the burned gases outside each cylinder 4, the base 11 of the cylinder head 10 is pierced with at least one exhaust pipe 30 which originates on the cylinder head 13 and which opens into an exhaust manifold 18 fixed to the cylinder head 10.

Finally, to regulate the flow rates of fresh air and exhaust gas burned in each cylinder 4, the cylinder head 10 comprises intake valves 21 and exhaust valves 31, controlled in position by camshafts 22, 32. For the fuel admission of the cylinders 4, the cylinder head 10 comprises fuel injectors (not shown) which open into the intake ducts 20 or, alternatively, directly into the combustion chambers 6. To initiate the combustion of the mixture of fuel and fresh air in the cylinders, the cylinder head 10 comprises a spark plug 14 which opens into the combustion chamber 6.

To cool its various components, the engine block 2 comprises a cooling circuit 40 which is closed and in which circulates a cooling liquid (for example a mixture of water and glycol). This cooling circuit 40 comprises a conduit and a water pump (not shown in the figures) which makes it possible to generate a continuous circulation of coolant in this conduit. As shown in Figure 1, this duct is formed of a plurality of channels 41, 42, 43, 44 of particular shapes that pass through the cylinder block 3 and the cylinder head 10. During operation of the engine, particles of Hot oil mixes with the hot gases contained in the oil sump 5. In addition, a small portion of the flue gases escapes from the combustion chamber 6 to the oil sump 5 passing between the pistons 8 and the cylinders 4. These burnt gases also mingle with the hot gases contained in the oil sump 5. These gases evacuated from the sump, mixed with each other, under pressure and loaded with oil are commonly known as "blow-off gas". by ».

In order to evacuate these pressurized gases by first extracting from them the oil they contain, the internal combustion engine 1 comprises a settling and evacuation circuit 50. This decanting and evacuation circuit 50 comprises firstly a decanter 100, which is designed to extract oil from the exhaust gases from the oil sump. It also comprises a first channel 51 designed to bring the gases discharged from the oil sump to the decanter 100. This first channel 51 originates in the oil sump 5, passes through a portion of the cylinder block 3, and opens into the decanter 100. It also comprises a second channel 52 designed to evacuate the gases after they have been treated by the decanter 100. This second channel 52 originates in the decanter 100 and opens into the inlet duct 20, such that these gases discharged from the oil pan and then treated are then burned in the combustion chamber 6. Finally, it comprises a control valve (not shown) of the flow rate of gas to be treated, which is generally located in the first channel 51 In Figures 2 to 4, there is shown the oil settler 100, which is more particularly the object of the present invention.

As shown in Figures 2 and 3, the oil decanter 100 comprises a casing 101 consisting of two elements, including a housing 103 which is formed by molding aluminum, and a rear wall 102 which is formed by cutting by cutting. an aluminum strip. The housing 103 generally has an elongated front wall 104, which is lined at the rear by a side wall 105. This housing 103 is open towards the rear. The side wall 105 is itself bordered at the rear by an outer peripheral return 105A, which extends in a plane parallel to the mean plane of the front wall 104.

The rear wall 102 is designed to close the rear opening of the housing 103. It has for this purpose a contour substantially identical to that of the outer peripheral return 105A. This housing 101 is equipped with securing means 130 to the engine block 2.

These securing means comprise, on the outer peripheral return 105A of the housing 103, six openings of fastening screw passages aligned with six openings of passages provided in correspondence in the rear wall 102.

The housing 101 of the decanter 100 is thus adapted to be attached by its rear wall 102 on the engine block 2, and to be screwed thereon by means of six fixing screws (not shown). In a conventional manner, the casing 101 defines internally a settling chamber 110 of the gases discharged from the oil sump (see FIG. 4). It also has at least one inlet 111, 112 of gases discharged from the oil sump, charged with oil vapors and with liquid oil particles, at least one outlet 116 of decanted gases, and at least one evacuation outlet. of oil 113 in the liquid phase. According to a particularly advantageous characteristic of the invention, the housing 101 also delimits a cooling channel 120 (see FIG. 4) which is hermetically isolated from the settling chamber 110. It furthermore has at least one inlet 160 and at least one outlet 150 of coolant. As best shown in FIG. 4, the internal volume of the housing 101 is divided into two parts by a single internal partition 106 which isolates the cooling channel 120 from the settling chamber 110.

The settling chamber 110 has a generally parallelepiped shape, with a volume substantially equal to 0.6 liter. The bottom 112 of this settling chamber 110, on which the oil extracted from the gases discharged from the oil sump, is formed by the upper face of the inner partition 106.

The face of the settling chamber 110, which is situated opposite this bottom 112, is here called the ceiling 119. It is carried on the side wall 105 of the housing 103. In order to optimize the condensation rate of the oil vapors contained therein in the gases discharged from the oil sump which pass through the settling chamber 110, there are provided first fins 114 which extend from the bottom 112 of the settling chamber 110, orthogonally thereto, up to the vicinity of the ceiling 119, and second fins 115 which extend from the ceiling 119 of the settling chamber 110, orthogonally thereto, to near the bottom 112.

These different fins 114, 115 make it possible to increase the total internal surface of the settling chamber 110. The oil vapors contained in the gases evacuated from the oil sump are thus likely to condense on a larger surface area. increases their rate of condensation.

These different fins 114, 115 here extend in parallel planes, which are orthogonal to the longitudinal axis of the housing 103. The first and second fins 114, 115 are alternately arranged (one of the second fins is located between each pair of first fins). These fins thus form inside the decantation chamber 110 a labyrinth which forces the gases discharged from the oil sump to follow a non-rectilinear trajectory, which makes it possible to project the liquid oil particles contained in these gases against the The oil thus extracted from the gases evacuated from the oil sump then flows by gravity into the bottom 112 of the settling chamber 110. To recover this oil and return it to the sump of the oil sump. oil 5, there is provided a hollow recess 111 in the inner partition 106. As shown in Figure 3, the rear wall 102 is then opened by a window 113 which is located in the extension of this cavity 111 and which is arranged to open into the oil sump 5.

This rear wall 102 is also opened by two windows 111, 112 which are respectively located at both ends of the settling chamber 110 and which are connected to the first channel 51 of the settling circuit 50. These two windows 111, 112 thus form two inputs gas evacuated from the oil sump inside the settling chamber 110.

It is also provided, projecting from the side wall 105 of the housing 103, a tubular connection 116 which originates in the ceiling 119 of the settling chamber 110 and on which a hose for evacuation of the gases discharged from the oil sump can be fitted and secured with a clamp. This tubular connection 116 thus forms the gas outlet to the inlet duct 20 of the cylinder head 10. As shown in FIG. 4, the cooling channel 120 also extends in length. It extends more precisely along the settling chamber 110, under it, to promote heat exchange between the coolant (whose temperature is about 90 ° C) and the gases evacuated from the crankcase. oil (whose temperature is about 140 ° C). The circulation of cooling liquid in this cooling channel 120, under the inner partition 106, allows in particular to cool the fins 114, which promotes the rate of condensation of the oil vapors in the settling chamber 110. The inlet 160 and the coolant outlet 150 in the cooling channel 120 are provided at the ends of this channel. The side wall 105 of the housing 103 carries for this purpose, at one of the two ends of the housing 101, a tubular connection 160 on which a flexible hose for the arrival of cooling liquid can be fitted and fixed with the help of a clamp. It also comprises, at the other end of the housing 101, an outlet duct 150 whose free end is arranged to be connected to the inlet of the water pump.

Advantageously, as shown in Figures 2 and 4, the housing 101 also defines a receiving housing 140 of a thermostat 200 having a valve (not visible in the figures). The housing 101 has for this purpose a platform 141 (Figure 2) on which is fixed a fastening flange 201 provided on the thermostat 200. It also defines a coolant passage 142 (Figure 4) in which is engaged the valve of the thermostat 200. As shown in the figures, the thermostat 200 is double-acting, in that it allows, when the engine is cold, to bypass the radiator so as to promote the rise in temperature of the engine block 2.

The casing 101 of the decanter 100 comprises for this purpose a tubular connector 170 which originates in the receiving housing 140 and on which a flexible hose of coolant can be fitted and fixed by means of a clamping collar. The passage of coolant in this hose then allows to short-circuit the radiator.

As shown in Figures 2 to 4, there is also provided on the outlet duct 150 another tubular connection 180 which originates in this outlet duct and on which a flexible hose degassing can be fitted and fixed using a clamp. This tubular connection 180 makes it possible to connect the cooling circuit to an expansion tank (not shown), which makes it possible to absorb the variations in the volume of the coolant when the temperature of the engine varies. Thanks to the receiving housing 140 of the thermostat 200, to the outlet duct 150 which connects directly to the water pump, and to the tubular connectors 170, 180, the decanter 100 thus centralizes various functions. It thus frees up space on the engine block, which facilitates the design and assembly of this engine block. Here, the decanter 100 is more precisely fixed on the lateral face of the cylinder block 3 which faces upwards, which favors the raising of the gases discharged from the hot oil sump into the settling circuit 50. cylinders 3 also defines internally a pre-settling chamber (not shown), with a volume of about 0.3 liter, for initiating the condensation of the oil vapors before the gases evacuated from the oil sump do not enter the decanter 100.

For this purpose, this pre-settling chamber has an inlet into which the first channel 51 of the settling circuit 50 opens, and two outlets situated opposite the inlets 111, 112 provided on the housing 101 of the settling tank 100. The present invention It is by no means limited to the embodiment described and shown, but the person skilled in the art will be able to make any variant that is in keeping with his spirit. In particular, it would be possible for the decanter housing to come from a one-piece plastic molding formation (with the exception of the internal partition 106).

It is also possible to provide for the cooling channel and / or the settling chamber to have a different shape, provided that the circulation of the cooling liquid makes it possible to reduce the temperature of the gases discharged from the oil sump. The cooling channel could for example form a spiral around the settling chamber.

In Figure 1, the decanter is shown mounted on a spark ignition engine. The invention is of course applicable to all types of engines (compression ignition, V architecture, ...).

Claims (10)

REVENDICATIONS1. Decanter (100) having a housing (101) which internally delimits a settling chamber (110) of gases discharged from an oil sump, characterized in that the housing (101) also internally delimits a cooling channel (120) for the coolant passage, which is hermetically isolated from said settling chamber (110). Decanter (100) according to the preceding claim, wherein said cooling channel (120) and said settling chamber (110) extend in length, and wherein said cooling channel (120) runs along said settling chamber ( 110). 3. Decanter (100) according to one of the preceding claims, wherein said cooling channel (120) is isolated from said settling chamber (110) by an inner partition (106) of the housing (101). 4. Decanter (100) according to one of the preceding claims, wherein the housing (101) comprises a connecting wall (102) to be applied against a corresponding wall of an engine block (2), which delimits at least one inlet (111, 112) of gas evacuated from the oil sump inside said settling chamber (110), and at least one outlet (113) for discharging oil to the engine block (2). 5. Decanter (100) according to the preceding claim, wherein the housing (101) defines at least one inlet (160) of coolant inside said cooling channel (120) and at least one outlet (150) of coolant, which are located at a distance from said junction wall (102). 6. Decanter (100) according to one of the preceding claims, wherein the housing (101) defines a receiving housing (140) of a thermostat (200). 7. Internal combustion engine (1) comprising: - an engine block (2) provided with a cylinder block (3), an oil sump (5) 30 located under the cylinder block (3) , and a cylinder head (10) covering the cylinder block (3), - a cooling circuit (40) in which coolant circulates, and a settling circuit (50) in which exhaust gases are circulated. oil sump (5), characterized in that it comprises a decanter (100) according to one of the preceding claims, the housing (101) is attached to a portion of the engine block (2), whose channel cooler (120) is connected to the cooling circuit (40) and the settling chamber (110) is connected to the settling circuit (50). 8. Internal combustion engine (1) according to the preceding claim, wherein the decanter (100) is fixed on an outer face (3A) of the cylinder block (3). 9. Internal combustion engine (1) according to one of claims 7 and 8, wherein the cooling circuit (40) comprises a thermostat (200) of which a valve is located in the cooling channel (120) of the decanter ( 100). 10. Internal combustion engine (1) according to one of claims 7 to 9, wherein the cooling circuit (40) comprises a water pump having a coolant inlet, and wherein the housing (101) of the decanter (100) carries an outlet duct (150) of coolant which is directly connected to the inlet of the water pump.