JP2022548518A - device for injecting air into the exhaust - Google Patents

Abstract

An air injection system (4) for injecting air into the exhaust of a combustion engine (3), comprising an air injector (17) and a solenoid valve (20), the air injector (17) comprising: It comprises a cylinder head (6) and a cylinder head cover (13), the cylinder head cover comprising a body in which a first air pipe (25) is formed, the cylinder head comprising a second air pipe (26) and a gas exhaust. a body formed with a tube (9), the first air tube (25) being connected upstream of the air injection pump (19), the first air tube (25) being connected to the second air tube (26), the second air pipe (26) is connected downstream of the gas exhaust pipe (9), the solenoid valve (20) is fixed to the cylinder head cover (13) An air injection system (4) is disclosed, wherein a solenoid valve (20) is connected downstream of a first air pipe (25). [Selection drawing] Fig. 2

Description

The present invention relates to a device for injecting air into the exhaust of a combustion engine. The invention also relates to a system for injecting air into the exhaust of a combustion engine. The invention also relates to powertrains including such air injection devices and/or such air injection systems. The invention finally relates to motor vehicles including such powertrains and/or such air injection devices and/or such air injection systems.

An internal combustion engine of a motor vehicle may have a system for injecting air into the exhaust, also called a secondary air injection system. Injecting pressurized fresh air into the exhaust of a combustion engine burns certain residues in the exhaust. This combustion increases the temperature of the exhaust gas upstream of pollution control components such as catalytic converters, particulate filters, and selective catalytic reduction devices. Since these anti-pollution components are effective only at certain exhaust gas temperatures (eg, about 400° C.), their operation can be improved by integrating a system for injecting air into the exhaust. In particular, a system that injects air into the exhaust at engine start-up speeds up the temperature rise of the anti-pollution member to meet anti-pollution standards.

Systems that inject air into the exhaust generally consist of an air injection pump that pressurizes the air trapped at the outlet of the air filter, a solenoid valve that controls the air flow rate, and a system that diffuses the air toward the exhaust manifold. be. These systems consist of multiple tubes. These systems are therefore heavy and bulky, and it can be difficult to integrate them into the engine compartment. Additionally, these systems can easily become dirty. Interfaces between multiple tubes can also cause leaks. Therefore, systems for injecting air into the exhaust may be unreliable. Ultimately, multiple air tubes cause a pressure drop. Therefore, the air injection system's pump must be powerful enough to compensate for these pressure drops.

Presentation of the invention The object of the present invention is to provide a device for injecting air into the exhaust which overcomes the above-mentioned drawbacks and which improves the devices known from the prior art.

More precisely, the first subject of the invention is a particularly light and compact device for injecting air into the exhaust.

A second subject of the invention is a device for injecting air into the exhaust air so that it is not easily fouled.

A third subject of the invention is a device for injecting air into the exhaust that does not cause air leaks or exhaust gas leaks.

A fourth subject of the invention is a device for injecting air into the exhaust that produces minimal pressure drop.

A fifth subject of the invention is a device for injecting air into the exhaust that is easily accessible for the purposes of possible repair interventions.

The present invention relates to an air injection system for injecting air into the exhaust of a combustion engine, the air injection system comprising:
- a device for injecting air into the exhaust;
- a solenoid valve;
with
The air injection device includes a cylinder head and a cylinder head cover, the cylinder head cover including a body having a first air pipe formed therein, and the cylinder head having a body having a second air pipe and a gas exhaust pipe formed thereon. wherein the first air pipe can be connected upstream of the air injection pump, the first air pipe is connected downstream of the second air pipe, and the second air pipe is connected downstream of the gas exhaust pipe, a solenoid valve is fixed to the cylinder head cover, and the solenoid valve is connected downstream of the first air pipe.

The air injection system may comprise a second sealing device between the cylinder head and the cylinder head cover, the second sealing device sealing air or exhaust gases from the first air conduit or the second air conduit. leakage can be prevented.

The second seal device may include a metal seal.

The cylinder head may include a plurality of gas exhaust tubes and the second air tube may include a chamber and a plurality of air tube sections, each air tube section connecting upstream of said chamber. and each air tube section is respectively connected downstream of one of the gas exhaust tubes.

The first air tube may be arranged vertically above the second air tube, the second air tube may extend the first air tube, and the first air tube or the second air tube may The second air pipe is arranged vertically above the gas exhaust pipe so that condensate formed in the air pipe cannot stagnate in the first air pipe or the second air pipe.

The cylinder head cover may have a fixed interface for the solenoid valve, the fixed interface including a third sealing device intended to prevent leakage of air or exhaust gases.

The air injection system may comprise a support for the solenoid valve, said support being fixed directly to the cylinder head cover, the solenoid valve being fixed directly to said support, said support being , including an air collection chamber connected downstream of the first air conduit.

The cylinder head cover may have cutouts to increase the volume of the air collection chamber.

The air injection system may comprise a first sealing device between the cylinder head and the cylinder head cover, the first sealing device being able to prevent leakage of oil vapor to the outside of the cylinder head body, The first sealing device includes a resin seal.

The invention also relates to a powertrain comprising a combustion engine, the combustion engine comprising an air injection system as defined above.

The invention also relates to a motor vehicle with an air injection system as defined above and/or a powertrain as defined above.

These subjects, features and advantages of the present invention are explained in detail in the following description of one particular embodiment given as a non-limiting example with reference to the accompanying figures.

1 is a schematic illustration of a motor vehicle including a device for influencing air into the exhaust according to one embodiment of the invention; FIG. 1 is a cross-sectional side view of a combustion engine with a device for influencing air into the exhaust according to one embodiment of the present invention; FIG. 1 is an isometric view of a cylinder head cover of a device for influencing air into the exhaust; FIG. Figure 3 is an isometric view from above of a cylinder head cover; Figure 3 is an isometric view from below of the cylinder head cover;

Figure 1 schematically shows a motor vehicle 1 with a powertrain 2 according to an embodiment of the invention. The vehicle 1 may be of any type. In particular, vehicle 1 can be, for example, a private car, utility vehicle, truck or bus. The powertrain 2 comprises a combustion engine 3 and a system 4 for injecting air into the exhaust.

In the following description, upstream and downstream are defined with reference to the direction of natural flow of air or exhaust gases. Air or exhaust gas circulates from upstream to downstream. Also, the vehicle 1 is considered to be stationary on a horizontal plane. The vertical axis Z is represented by a vector directed from bottom to top.

The combustion engine 3 comprises an engine block 5 in which cylinders are formed, which are places of combustion of fuel, for example petrol or diesel. The number of cylinders can be any number, for example 3 cylinders, 4 cylinders, 6 cylinders, 8 cylinders, and so on. Combustion engine 3 also comprises a cylinder head 6 fixed to engine block 5 . The cylinder head 6 is a component of the combustion engine that closes the top of the cylinder. The cylinder head 6 houses or supports, among other things, an intake valve, an exhaust valve 7 and a camshaft 8 mechanically connected to the intake and exhaust valves 7 . An exhaust valve is a mechanical member that separates each cylinder from the gas exhaust pipe 9 . The gas exhaust pipe 9 is a channel formed in the cylinder head for discharging exhaust gases, ie gases resulting from the combustion of fuel in the cylinder. The cylinder head may contain as many separate gas exhaust pipes 9 as there are cylinders. Each gas exhaust pipe carries exhaust gases from the cylinder towards the outside of the cylinder head.

The powertrain also comprises an exhaust system, for example with an exhaust manifold 10 fixed to the cylinder head at the outlet of the gas exhaust pipe 9 . The exhaust manifold may contain as many inlets and a single outlet as there are gas exhaust tubes. The exhaust manifold is connected downstream of an exhaust pipe 11 which itself is connected downstream of a pollution control member 12 . The pollution control member is, for example, a catalytic converter, a particulate filter, a selective catalytic reduction device (also called an SCR device), or any device capable of disinfecting or reducing the content of particles in the exhaust gas. It can be another member. A pollution control member may require that the exhaust gases reach a temperature threshold, for example a threshold of about 400° C., in order to operate in an optimal manner.

Combustion engine 3 also comprises a cylinder head cover 13 . The cylinder head cover is the upper part of the combustion engine 3 and covers the cylinder head 6 . As shown in FIG. 2 , the cylinder head cover 13 may be attached to the cylinder head 6 so as to rest vertically thereon. A substantially horizontal plane P1 can vertically separate the cylinder head cover 13 from the cylinder head 6 . The cylinder head 6 may contain two lower half bearings 14 and the cylinder head cover 13 may contain two upper half bearings 15 . The two lower half bearings 14 cooperate with the two upper half bearings 15 to form two bearings supporting the two camshafts. The assembly formed by the cylinder head 6 and the cylinder head cover 13 forms a sealed internal volume 16 in which the camshaft 8 and the valve 7 can be specifically arranged. Oil in vapor or droplet form may be placed in this internal volume 16 to lubricate the various moving elements of the combustion engine, in particular the camshafts and valves.

The cylinder head and cylinder head cover can be an integral component. The cylinder head and cylinder head cover may be made of metal. Cylinder heads and cylinder head covers can be obtained by machining and/or casting. The cylinder head cover is fixed to the cylinder head in a sealed manner, for example by means of fixing screws. As seen in Figures 3, 4 and 5, the cylinder head and cylinder head cover may also include reinforcing ribs, openings intended to receive injectors and/or spark plugs, for example.

The system 4 for injecting air into the exhaust comprises an air injection device 17 formed in the cylinder head 6 and the cylinder head cover 13 . The system also includes an air filter 18 , an air injection pump 19 and a solenoid valve 20 . Air filter 18 is connected downstream of air injection pump 19 by a first external tube 21 . Air injection pump 19 is connected downstream of solenoid valve 20 by a second external pipe 22 .

The air filter 18 is a member capable of extracting and filtering fresh air from the outside. In particular, the air filter 18 may filter airborne particles to prevent further particles from entering the system for injecting air into the exhaust. The air filter 18 may also help filter the fresh air supplied to the cylinders via the intake manifold to allow combustion of the fuel.

Air injection pump 19 , or more simply air pump 19 , is a pump capable of pressurizing the air coming from air filter 18 . The air injection pump 19 can be electrically connected to an electrical energy source and an electronic control unit. Activation of the air injection pump 19 can be controlled by control commands issued by the electronic control unit.

The solenoid valve 20 is a member capable of controlling the flow rate of air passing through the solenoid valve 20 . Solenoid valve 20 may include a connector electrically connected to an electronic control unit. Control commands issued by the electronic control unit can control the flow of air through the solenoid valve. The solenoid valve 20 is fixed to the cylinder head cover 13 via a support 23 . The support 23 is directly fixed, eg screwed, to the cylinder head cover and the solenoid valve is directly fixed, eg screwed, to the support 23 . The support 23 is fixed to a fixed boundary surface 24 of the cylinder head cover, clearly visible in FIG. The solenoid valve is therefore held firmly against the combustion engine 3 without bulging. Such fixing of the solenoid valve is particularly reliable and vibration-resistant. The support 23 comprises an air collection chamber connected downstream of the air injection device 17 . The support 23 may also include channels upstream of the air collection chamber and downstream of the air injection device 17, connected to a first air tube 25 formed in particular in the cylinder head cover. As a variant, the support 23 and the cylinder head cover can form only one component. In other words, the solenoid valve can be fixed directly to the cylinder head cover.

The cylinder head cover may also include cutouts to conserve material and increase the volume of the collection chamber. This cutout can advantageously be located below the solenoid valve 20 .

The air injector 17, ie part of the system 4 for injecting air into the exhaust formed in the body of the combustion engine, will now be described in more detail.

The cylinder head cover 13 has a body in which a first air pipe 25 is formed. Similarly, the cylinder head comprises a body in which a second air tube 26 and a gas exhaust tube 9 are formed. Accordingly, the first air tube 25 and the second air tube are cutouts realized in the body of the cylinder head cover 13 and the body of the cylinder head 6 respectively. The first air tube 25 is connected (ie, butted) downstream of the second air tube 26 . A second air pipe 26 is connected downstream of the gas exhaust pipe 9 .

The first air pipe 25 thus comprises an inlet which can be arranged on the upper surface of the cylinder head cover and an outlet which can be arranged on the lower surface of the cylinder head cover, the lower surface being in contact with the cylinder head 6 . By following the first air tube from inlet to outlet, ie upstream to downstream, it can be seen that the first air tube follows a downward or locally horizontal trajectory.

Similarly, the second air tube 26 has an inlet located on the top surface of the cylinder head and an outlet that may be located on the side of the cylinder head. It can also be seen that by following the second air tube from inlet to outlet, ie from upstream to downstream, the second air tube follows a downward or locally horizontal trajectory.

The first air tube 25 is arranged above the second air tube 26 . A second air pipe extends the first air pipe 25 and is arranged above the gas exhaust pipe 9 . Therefore, liquid or condensate formed in the first air tube cannot stagnate there and is discharged under gravity toward the second air tube. Similarly, liquid or condensate formed in the second air tube cannot stagnate there and is discharged under gravity towards the gas exhaust tube 9 . In other words, neither the first air tube 25 nor the second air tube 26 contain low points that form a liquid retention volume. The orientation of the first air tube and the second air tube may be as vertical as possible to promote the flow under gravity of any liquid or condensate toward the exhaust tube.

1, 2 and 5, the assembly formed by the cylinder head and cylinder head cover includes a first sealing device 31 and a second sealing device 32, both of which lie in plane P1. between the cylinder head and the cylinder head cover. The first sealing device can prevent leakage of oil vapor to the outside of the assembly formed by the cylinder head and the cylinder head cover. A first sealing device may be arranged around an internal volume 16 in which the lubricating oil may be pressurized. The second sealing device can prevent leakage of air or exhaust gas from the first air pipe or the second air pipe of the air injector. A second sealing device is disposed about an interface formed between the first air tube and the second air tube. The second seal device may have a shape that substantially reproduces the cross-sectional shape of the first air tube and the second air tube, for example, a generally circular or generally rectangular shape.

Therefore, the two sealing devices are subject to different constraints. The first device is designed to withstand a lubricated oil laden environment and the second device is pressurized air coming from upstream or possibly high temperature sporadically rising upstream from the gas exhaust pipe 9 . designed to withstand the exhaust fumes of Advantageously, the first sealing device 31 may comprise a resin seal. The second seal device may include a metal seal. In alternative embodiments, the air injection device may include a single sealing device that is simultaneously resistant to oil, pressurized air, and exhaust gases. This single sealing device may be, for example, a metal seal. However, a single seal device is more complex and costly to implement than two separate seal devices of different types.

With reference to FIG. 4, the casing cover also comprises a third sealing device 33 arranged on the fixed interface 24 for the support 23 holding the solenoid valve 20 . Like the second sealing device, the third sealing device 33 is designed to withstand pressurized air coming from upstream or possibly exhaust gases sporadically rising upstream from the gas exhaust pipe 9. . A third sealing device may include a metal seal.

A system for injecting air into the exhaust that is formed in this way makes it possible to save air pipes compared to systems for injecting air into the exhaust that are known from the prior art. Specifically, the system of the present invention does not require piping between the solenoid valve 20 and the cylinder head cover. This saves space in the engine compartment where the combustion engine is located. Furthermore, the tube line formed by air tubes 25 and 26 serves to lighten the combustion engine.

Referring to Figure 2, the combustion engine 3 may be located a short distance from the hood 34 of the vehicle. The solenoid valve may be located for access directly under the hood 34 of the vehicle. Maintenance and/or possible replacement thereof is thus facilitated.

During operation of the combustion engine, fresh air is drawn in from outside by the air injection pump. Fresh air enters system 4 for injecting air into the exhaust through air filter 18 , then through first external tube 21 and then through air injection pump 19 . Air is pressurized by the air injection pump 19 , passes through the second external tube 22 and then reaches the solenoid valve 20 . The flow rate of air passing through the solenoid valve 20 can be adjusted according to the state of the solenoid valve controlled by the electronic control unit. The air then passes through the support 23 and then reaches the air injectors in the cylinder head cover 13 . The third sealing device 33 ensures that no air or exhaust gas leaks occur at the interface between the support 23 and the cylinder head cover. The air then passes through a first air tube 25 and reaches a second air tube 26 integrated into the cylinder head. The second sealing device 32 ensures that no air or exhaust gas leaks occur at the interface between the first air tube and the second air tube. The air then reaches chamber 27 and is distributed from there to air tube section 28 . Air is then injected into the gas exhaust pipe 9 as close as possible to the exhaust valve 7 . The passage of air from the outside to the gas exhausts provides low pressure drop and good distribution uniformity within the various gas exhausts 9 . The air mixed with the exhaust gas in this way enables the combustion of residues present in the exhaust gas. Therefore, the temperature of the exhaust gas can rise rapidly as soon as the combustion engine starts. Exhaust gases then exit combustion engine 3 and pass through exhaust manifold 10 , exhaust pipe 11 and pollution control member 12 . Due to the high temperature of the exhaust gases, the anti-pollution member operates optimally. The exhaust gas thus treated can then be discharged from the vehicle. When condensate forms in the system for injecting air into the exhaust, the condensate is directed under gravity towards the gas exhaust pipe 9 . Condensate therefore cannot stagnate or accumulate in one of the tubes of the system for injecting air into the exhaust. In parallel with this operation, various moving parts within the cylinder head 6 can be lubricated with oil under pressure. Pressurized oil is prevented from escaping through the interface between the cylinder head cover and the cylinder head due to the first sealing device 31 .

Claims (11)

An air injection system (4) for injecting air into the exhaust of a combustion engine (3), comprising:
an air injector (17);
a solenoid valve (20);
with
The air injection device (17) includes a cylinder head (6) and a cylinder head cover (13), the cylinder head cover including a body having a first air pipe (25) formed therein, the cylinder head comprising: It comprises a body in which a second air pipe (26) and a gas exhaust pipe (9) are formed, said first air pipe (25) being capable of being connected upstream of an air injection pump (19). The first air pipe (25) is connected downstream of the second air pipe (26), and the second air pipe (26) is connected to the gas exhaust pipe (9). The solenoid valve (20) is fixed to the cylinder head cover (13), and the solenoid valve (20) is connected downstream of the first air pipe (25). An air injection system (4), characterized by: a second sealing device (32) between the cylinder head (6) and the cylinder head cover (13), wherein the second sealing device is connected to the first air pipe or the second air pipe 2. An air injection system (4) according to claim 1, characterized in that it is possible to prevent leakage of air or exhaust gases from the . An air injection system (4) according to claim 2, characterized in that said second sealing device (32) comprises a metal seal. Said cylinder head (6) comprises a plurality of gas exhaust pipes (9) and said second air pipe (26) comprises a chamber (27) and a plurality of air pipe portions (28), each air pipe A section (28) is connected upstream of said chamber (27) and each air tube section is connected respectively downstream of one of said gas exhaust tubes (9). 4. An air injection system (4) according to any one of claims 1 to 3. Said first air tube (25) is arranged vertically above said second air tube (26), said second air tube (26) extending said first air tube (25). and condensate formed in said first air pipe (25) or said second air pipe (26) cannot stagnate in said first air pipe or said second air pipe. 5. An air injection system according to any one of claims 1 to 4, characterized in that said second air pipe (26) is arranged vertically above said gas exhaust pipe (9). (4). Said cylinder head cover (13) comprises a fixed boundary surface (24) for said solenoid valve (20), said fixed boundary surface (24) being a third interface intended to prevent air or exhaust gas leakage. 6. An air injection system (4) according to any one of the preceding claims, characterized in that it comprises a sealing device (33). A support (23) for a solenoid valve, said support (23) being fixed directly to said cylinder head cover (13) and said solenoid valve (20) being directly fixed to said support (23) 7. Air injection according to any one of claims 1 to 6, characterized in that the support comprises an air collection chamber connected downstream of the first air conduit (25). system (4). 8. An air injection system (4) according to claim 7, characterized in that the cylinder head cover comprises cutouts for increasing the volume of the air collecting chamber. A first sealing device (31) is provided between the cylinder head (6) and the cylinder head cover (13), and the first sealing device prevents oil vapor from flowing out of the body of the cylinder head (6). 9. An air injection system (4) according to any one of the preceding claims, characterized in that it is leak proof and said first sealing device (31) comprises a plastic seal. A powertrain (2) comprising a combustion engine (3), characterized in that said combustion engine (3) comprises an air injection system (4) according to any one of claims 1 to 9. A motor vehicle (1) comprising an air injection system (4) according to any one of claims 1 to 9 and/or a powertrain (2) according to claim 10.

Images