WO2019121552A1 - Internal combustion engine assembly with controlled ignition injecting a pulverised anti-knock agent into an intake manifold - Google Patents

Abstract

The invention relates to an internal combustion engine (1) assembly comprising: - an intake manifold (2) comprising: a plurality of intake ducts (21); a tubular plenum (3) serving compressed air into all the intake ducts (21) via a main inlet (30); - a tank (5) containing a pulverised anti-knock agent. According to the invention, the tubular plenum (3) comprises a Venturi throat arranged upstream of the main inlet. The tank (5) of pulverised anti-knock agent leads into the tubular plenum (3) at the Venturi throat. The assembly also comprises a forced circulation system pushing the pulverised anti-knock agent towards the tubular plenum (3).

Description

 Spark ignition internal combustion engine unit injecting an anti-rattling spray agent into an intake manifold

The invention relates to a spark ignition internal combustion engine assembly for the injection of a powdered anti - rattling agent into an intake manifold or intake manifold of the engine.

 In a known manner, car manufacturers offer different methods for increasing the power of the engine while driving the vehicle. One of these methods is to inject compressed air into combustion chambers in order to improve their filling rate. The compressed air is sent from a compressor driven by the engine or from a turbocharger driven by the exhaust gas flow. This method is still called the engine boost.

 However, for a spark-ignition engine (of the type operating for example with gasoline), the supercharging of the engine makes the latter more sensitive to rattling, a phenomenon of uncontrolled combustion of the fuel in the combustion chamber before combustion does not occur. triggered by the spark plug. Knocking usually occurs in places where pressure and temperature are high, especially at the walls of the firebox. The rattling is manifested by a metallic noise, perceptible to the ear or can be detected by a piezoelectric sensor. The rattling can severely degrade the piston as well as the cylinders.

In order to reduce the risk of rattling, one of the existing solutions is to introduce an anti-rattling agent into combustion chambers. By definition, an anti-knock agent is a fuel that has a higher octane number than the fuel (eg gasoline) that is primarily consumed in the engine for fuel. couple production. The anti-knock agents commonly used are ethanol, methyl tert-butyl ether (MTBE), tert-butyl ethyl ether (ETBE).

 This solution is described in document US 2006/0102146. In this document, the anti-knock agent is either introduced directly into the combustion chambers or premixed with gasoline, the mixture thus obtained then being sent into the combustion chambers.

 However, this solution is still perfectible, especially in terms of distribution of anti-rattling agent in the combustion chambers. A non-homogeneous mixture of the anti-knock agent reduces the performance thereof.

 In addition, it is necessary to install a cylinder injection system, either for the anti-rattling agent alone, or for mixing the anti-rattling agent with the fuel, which complicates the structure, therefore the manufacture, of the engine and adds a potential source of failure in the engine.

 Thus, an object of the invention is to provide an internal combustion engine assembly for a homogeneous distribution of the anti-rattling agent in the combustion chambers, thus an optimal efficiency to prevent or prevent knocking.

 Another object of the invention is to provide such a set which is economical and reliable to install.

 For this purpose, the invention relates to an internal combustion engine assembly comprising

 - an intake distributor comprising

 • several intake ducts;

 • a tubular plenum serving compressed air in all intake ducts via a main entrance;

A reservoir containing a spray anti-rattling agent. According to the invention, the plenum comprises a Venturi neck disposed upstream of the main entrance. The reservoir of spray anti-knock agent opens into the plenum at the level of the Venturi neck. The assembly further includes a forced circulation system moving sprayed anti-rattling agent to the plenum.

 On the one hand, the forced circulation system forces the spray anti-rattling agent to move to the plenum. On the other hand, the presence of the Venturi neck in the plenum makes it possible to lower the pressure at this level, which facilitates the entry of the spray anti-rattling agent into the plenum. Thus, the pulverized anti-rattling agent can be introduced into the plenum despite a high pressure of the compressed air circulating therein.

 In addition, the anti-rattling agent being sprayed, the mixture thereof with compressed air in the tubular, is made homogeneously.

 Since the anti-rattling agent opens into the Venturi neck upstream of the main inlet, the homogeneous mixture of the anti-rattling agent with compressed air is produced before it is dispensed to all intake ducts from the plenum. The inlet ducts of the distributor open into corresponding combustion chambers of the engine. Thus, the homogeneous mixture of the anti-rattling agent with compressed air is sent into each of the combustion chambers, which allows a homogeneous distribution of the anti-rattling agent in each combustion chamber, thus an optimal performance. anti-rattling agent to prevent rattling.

Moreover, the assembly does not require much change in the structure of the engine itself, including the structure of the cylinder head of the engine, because it does not need an individual injection system cylinder. A distributor whose tubular plenum is equipped with a collar of Venturi is sufficient to serve the homogeneous mixture to all the inlet ducts of the distributor and then to all the combustion chambers.

 According to a feature of the invention, the assembly comprises a butterfly valve preceding the tubular distributor. The Venturi neck is preferably arranged in alignment with the butterfly valve. In fact, the shorter the path of the gas stream between the butterfly valve and the neck, the higher the dynamics of this vein. Conversely, a large distance between the butterfly valve and the neck tends to slow the dynamics of the gas stream, which results in a degradation of the behavior of the engine in transient.

 According to one characteristic of the invention, the forced circulation system comprises

 - a first tapping on the plenum of the distributor upstream of the Venturi pass;

 - a second stitching on the reservoir sprayed anti-knock agent;

 A connection duct connecting the first quilting to the second quilting; and

 - A non-return valve installed in the connection duct so as to allow the circulation of the compressed air from the first tapping to the second tapping.

In this way, on the one hand, the pressure at the second tapping, that is to say at the level of the bore in the anti-knocking agent reservoir, is substantially equal to the pressure of the compressed air in the plenum. On the other hand, the tank opens into the plenum at the level of the Venturi neck where the pressure is lower than the pressure of the compressed air flow in the plenum. The pressure difference at the second stitching and at the Venturi neck thus displaces the spray anti-rattling agent into the plenum of the manifold. According to a characteristic of the invention, the forced circulation system comprises a pump connected to the spray anti-rattling agent reservoir and arranged in such a way as to be able to inject the pulverized anti-rattling agent under pressure.

 According to one characteristic of the invention, the forced circulation system comprises a deformable membrane wall constituting one of the walls of the spray anti-rattling agent reservoir, and an actuating member for deforming the deformable membrane wall. Thus, the wall can be deformed so as to reduce the volume of the tank and thus increase the pressure in the tank so that it is greater than the pressure at the Venturi neck.

 According to one characteristic of the invention, the set comprises

 - a knock detector;

 - a compressed air flow estimator;

 a solenoid valve installed in a pipe leading from the anti-rattling agent to the plenum of the distributor;

 a control unit for controlling the solenoid valve to introduce a quantity of anti-rattling agents adapted according to the signal of the knock sensor and the compressed air flow estimator.

 Thus, all these elements make it possible to introduce the appropriate amount of anti-rattling agent according to the type of rattling detected in order to optimize efficiency to avoid rattling. Furthermore, the control unit allows economical management of the motor assembly according to the invention. Indeed, it can operate the motor assembly only in case of need.

According to a feature of the invention, the motor assembly comprises an ultrasonic spray apparatus and an additional pump preceding the anti-tank agent reservoir. rattling sprayed. The additional pump introduces liquid anti-rattling agent into the ultrasonic spray apparatus which then transforms it into liquid spray form.

 Other characteristics and innovative advantages will emerge from the following description, provided for information only and in no way limitative, with reference to the appended drawings, in which:

 FIG. 1 schematically represents a perspective view of an engine assembly according to the invention

 - Figure 2 shows schematically a top view of the motor assembly of Figure 1;

 FIG. 3 schematically represents a cross-sectional view illustrating constituent elements of the motor assembly of FIG. 1.

 The structurally and functionally identical elements, present in several distinct figures, are assigned a single numerical or alphanumeric reference.

 With reference to FIG. 1, an exemplary embodiment of a motor assembly 1 according to the invention is illustrated. The engine assembly 1 comprises an intake manifold 2, also called intake manifold 2, composed of several intake ducts 21 each opening into a cylinder of the engine and a plenum 3 serving air in all intake ducts 21 of the distributor.

 Plenum 3 is tubular in shape, oblong, generally cylindrical.

 Here, the intake ducts 21 are arranged parallel to each other along an intake face (not shown) of the engine. The tubular plenum 3, hereinafter called plenum, extends parallel to the intake face and communicates with each intake duct 21 via an opening

31 practiced on its lateral side. In an exemplary embodiment of the invention the distributor consists of two separate parts: a first part which comprises the intake ducts 21 and a first half-cylindrical portion of the plenum 3, and a second part which consists of the Another half-cylindrical portion of the plenum 3. For example, the two parts are previously made of injected plastic, and they are then welded together at a joint plane which connects the two semi-cylindrical portions of the plenum 3. Alternatively, the distributor can be made in one piece, for example by molding the plastic part around a fuse metal core whose shape corresponds to the volume of the plenum and ducts, and then melting the core.

 According to the invention and in this example, in order to increase the power of the engine, the compressed air is sent into the cylinders via the intake manifold 2. A butterfly valve 4 is installed upstream of the distributor 3 to regulate the flow Compressed air admitted first to manifold 3 of intake manifold 2. Unless otherwise stated, the terms "before" and "after", "upstream" and "downstream" are defined in relation to the direction of flow. air in the engine assembly 1.

 The compressed air comes from an air intake circuit comprising a compressor which can be driven by the engine or by a source of electrical energy, or by a turbocharger whose turbine drives the exhaust gases and transfers the fuel. energy of the expansion of the gases to the compressor.

 In the illustrated example, the opening diameter of the butterfly valve 4 can be modified by means of a motorized control box 41 shown in FIG. 1 and FIG.

2.

The motor assembly 1 further comprises a reservoir 5 which contains an anti-knock agent, for example ethanol as a sprayed liquid. In this state, the anti-rattling agent is in very fine droplets forming a so-called mist or mist, as the state of a liquid dispensed by a nebulizing nozzle. To obtain this mist, an ultrasonic spray apparatus 51 is used, in this example, next to the tank 5. In a first step, the liquid anti-rattling agent is sent into the spray apparatus 51 by means of an additional pump. In a second step, the anti-rattling agent thus sprayed is sent into the tank 5 for storage.

 In FIG. 2 and in FIG. 3, the anti-knocking agent is introduced into a portion 33 of the plenum 3 located between the butterfly valve 4 and a main inlet 30. The main entrance 30 is understood to mean the location of the plenum of the plenum. distributor through which the airflow passes before being distributed in each intake duct of the distributor. In other words, the main entrance 30 can be considered as a section 30 of the distributor 2, more precisely the plenum 3 of the distributor 2, located before the first lateral opening 31 opening into the intake duct 21 which is located closest to 4. In this example, the intake duct 21 located closest to the butterfly valve 4 is the rightmost one in FIG. 2. The main inlet is illustrated by a line denoted 30.

 In FIG. 3, the tank 5 opens into the plenum

3 at the level of a Venturi 6 neck placed between the butterfly valve

4 and the main entrance 30. The spray anti-rattling agent enters the plenum 3 via an orifice 32 made on a wall 34 of the plenum, the orifice 32 being placed at the level of the neck of the Venturi 6.

The purpose of the establishment of the Venturi neck 6 is to lower the pressure locally in the plenum 3 in order to facilitate the introduction of the spray anti-rattling agent. Indeed, the spray anti-rattling agent is stored in the tank 5 at atmospheric pressure P _atm . When the compressed air is sent into the inlet manifold 2, the pressure in the plenum Pi of the distributor becomes higher than the atmospheric pressure P _atm . It is therefore necessary to find a means for locally lowering the pressure in the plenum 3 of the distributor to be able to introduce the anti rattling agent pulverized.

 The means proposed by the motor assembly 1 according to the invention is to arrange the Venturi neck 6 between the butterfly valve 4 and the main inlet 30, because in a manner known per se, the velocity of the fluid at the level of the Venturi neck 6 increases, which has the effect of lowering the pressure of the fluid at this point to a pressure P2 less than the pressure Pi of the flow of compressed air in the plenum 3. In other words, the local decrease of the pressure sucks the anti-rattling agent sprayed in the plenum 3.

 The ratio of the diameter of the Venturi neck di and the diameter d2 of the other non-narrowed sections of the plenum 3 (i.e. the other tubular sections of the plenum before and after the neck) can be determined by the following equation:

(Equ.l) Pi - P2 = ½ · p · V1 ² · [(d2 / di) ² - 1]

With

 Pi the static pressure upstream of the collar

 P2: the static pressure in the neck

P: the density of the air-agent mixture, calculated from the rat) o air-agent which is provided

 Vi: the speed of the airflow upstream of the neck

 The ratio of diameters will be chosen so that the following two conditions are fulfilled simultaneously:

Pi P2> 0 And

 The flow velocity remains in the subsonic domain, i.e. vi <Mach 1.

 In this example, the neck of the Venturi 6 is advantageously placed in alignment with the butterfly valve 4, or more exactly the opening 42 of the butterfly valve 4, so as to improve the dynamics of the air stream.

 In order to force the flow of the spray anti-rattling agent towards the distributor 3, the engine assembly 1 according to the invention provides a forced circulation system 7. In the example illustrated, this system 7 comprises a first sewing 71 on the plenum 3 upstream of the neck of the Venturi 6, a second stitching 72 on the tank and a connecting pipe 73 connecting the first stitching 71 to the second stitching 72. The forced circulation system 7 further comprises a non-return valve 74 installed so as to allow only the displacement of the fluid in the direction of the plenum 3 towards the reservoir 5.

 The forced circulation system 7 thus allows a part of the compressed air flow at pressure Pi to go to the second stitching 72. As a result, the pressure at the second stitching P3 is relatively close to the pressure of the flow. This is in addition to the effect of the suction created by the Venturi neck 6 to move the mist consisting of the sprayed agent to the plenum 3.

 Moreover, the forced circulation system 7 makes it possible to reduce or even eliminate the effect of the friction of the anti-pinging agent sprayed against the walls of the tank 5, this friction being unfavorable to the flow of the fog towards the plenum 3 .

According to the invention and in this example, the motor assembly 1 further comprises a knock detector, a flow meter measuring the amount of compressed air fed into the distributor 2, a solenoid valve 8 acting on the flow rate of the spray anti-rattling agent sent into the distributor 2.

 The knock detector is for example a piezoelectric sensor fixed on a crankcase (or engine block) of the engine so as to be able to measure the vibration frequency of the crankcase. Indeed, rattling is a detonating inflammation that generates vibrations propagated in the crankcase. So, one of the ways to detect rattling is to measure vibration frequencies.

 The solenoid valve 8 is installed in a pipe 52 connecting the tank 5 to the plenum 3. Precisely, the solenoid valve 8 is arranged, in this example, before the orifice 32 made on the wall 34 of the plenum 3 at the Venturi neck . The term "before" here is defined with respect to the direction of flow of the spray anti-rattling agent.

 The engine assembly 1 also includes a control unit is able to control, control one or more electronic components. The control unit is also able to receive data measured by at least one of these electronic components and give a decision based on these data. The decision is generally the actuation or adjustment of one of the parameters of the electronic components. In this example, the control unit is connected to the knock detector, the flow meter and the solenoid valve 8.

 We will now describe the operation of the motor assembly.

The knock detector measures the crankcase vibration frequency and determines whether the measured frequency is in a predefined rattling spectrum. This spectrum is a range of frequencies in which rattling is believed to be present. If this is the case, the knock detector translates the measured frequency into an electrical signal, for example in voltage, and sends this signal to the control unit. This last determines, based on the signal reported, the degree of severity of the detected knock. For example, it is slow or nascent type rattling and franc type rattling. Slow rattling is less severe than straight rattling.

 Once the type of knock is determined, the control unit acts on the solenoid valve 8 so that it introduces the amount of the anti-rattling agent adapted. For example, a large quantity of the anti-ping agent sprayed in the case of free rattling is required. It should be noted that the control unit may also be required to reduce the ignition advance immediately in order to protect the motor.

 The amount of the anti-rattling agent also depends on the amount of air admitted into the distributor 2 and the amount of fuel that is injected into the engine, for example directly into the engine cylinders. The quantity of air is measured and sent to the control unit by the flowmeter. The amount of fuel can be determined by the fuel injection time determined by the control unit.

 At most of its operating speed-load points, a spark-ignition type engine operates at richness 1, i.e., in stoichiometric proportions. For example, for an engine operating with a fuel that is pure gasoline, the ratio air: fuel is substantially equal to 14.7: 1, that is to say that the engine admits 14.7 g of air to burn 1 gram of fuel. For an engine running on a fuel that is pure ethanol, the ratio of air to fuel is only 9: 1, that is to say, it is necessary to admit 9 g of air to burn 1 g fuel .

In the case of an engine running on a main fuel that is gasoline and with an anti-knock agent which is pure ethanol, for example, in the case of slow rattling, the proportion of compressed air and pulverized anti-knock agent may be 0.9: 1, with simultaneous adaptation of the ratio air: gasoline to the value 13,23: 1, which corresponds to the introduction of 10% introduction of ethanol. In the case of rattling franc, this proportion air: ethanol can be 3, 6: 1, the ratio air: petrol being equal to 8,82: 1, which corresponds to the introduction of ethanol up to 40 %.

 In both cases, the anti-knock agent is pulverized in a suitable amount in the plenum 3. The stirring of the anti-rattling agent sprayed with compressed air from the air intake circuit is carried out using the air flow rate in the plenum 3 of the distributor 2, in particular at the Venturi neck 6 where the spray anti-rattling agent opens. The mixture thus obtained is homogeneous and ready to be sent into the intake ducts 21, then into the combustion chambers to participate in the thermodynamic cycle of the engine, that is to say to the combustion.

 Of course, it is possible to bring to the invention many modifications without departing from the scope thereof.

 For example, the forced circulation system 7 may comprise, in addition to the connecting duct 73 and the taps 71, 72 previously described, a deformable membrane wall forming part of the walls of the tank 5. An actuating member deforms this wall by to change the pressure in the tank. Alternatively, the forced circulation system may comprise only the deformable membrane wall and the actuating member.

Claims

1. Internal combustion engine assembly (1) comprising  an intake distributor (2) comprising • several intake ducts (21); A tubular plenum (3) serving compressed air in all the intake ducts (21) via a main inlet (30);  a reservoir (5) containing a spray anti-knock agent;  said assembly being characterized in that  the tubular plenum (3) comprises a Venturi neck (6) disposed upstream of the main inlet (30);  - the reservoir (5) sprayed anti-knock agent opens into the tubular plenum (3) at the Venturi neck (6);  the assembly comprises a forced circulation system (7) moving pulverized anti-rattling agent towards the tubular plenum (3). 2. Assembly (1) according to claim 1, characterized in that the assembly (1) comprises a butterfly valve (4) preceding the tubular plenum (3) and in that the neck of the Venturi (6) is disposed in the alignment of the butterfly valve (4). 3. An assembly according to claim 1 or claim 2, characterized in that the ratio between the diameter (di) of the Venturi neck (6) and the diameter (d2) of the radially narrowed portion of the tubular plenum (3). is determined so that the pressure (P2) at the Venturi neck is less than the pressure (Pi) at the level of the radially narrowed part of the plenum and that the gaseous flow in the neck remains in the subsonic domain. 4. Assembly (1) according to one of claims 1 to 3, characterized in that the forced circulation system (7) comprises  - a first stitching (71) on the tubular plenum (3) upstream of the Venturi neck (6);  - a second stitching (72) on the reservoir (5) sprayed anti-knock agent;  a connection duct (73) connecting the first quilting (71) to the second quilting (72); and  - A non-return valve (74) installed in the connection duct (73) so as to allow the circulation of compressed air from the first quilting (71) to the second quilting (72). 5. Assembly (1) according to one of claims 1 to 4, characterized in that the forced circulation system (7) comprises a deformable membrane wall constituting one of the walls of the reservoir (5) sprayed anti-rattling agent , and an actuator for deforming the deformable membrane wall. 6. Assembly (1) according to one of the preceding claims, characterized in that the assembly comprises  - a knock detector;  - a compressed air flow estimator;  - a solenoid valve (8) installed in a pipe (52) leading the anti-rattling agent to the tubular plenum (3); a control unit for controlling the solenoid valve (8) for introducing a quantity of anti- ratchet adapted according to the signal of the knock detector and the compressed air flow estimator. 7. Assembly (1) according to one of the preceding claims, characterized in that it comprises an ultrasonic spray apparatus (51) and an additional pump preceding the reservoir (5) sprayed anti-rattling agent. 8. Motor vehicle characterized in that it comprises a motor assembly (1) according to one of the preceding claims.