CN114430789A

CN114430789A - Device for injecting air into an exhaust

Info

Publication number: CN114430789A
Application number: CN202080066511.7A
Authority: CN
Inventors: F·阿尔梅达; J·勒斐伏尔; V·菲利普; T·维尼齐亚尼
Original assignee: Renault SAS
Current assignee: Renault SAS
Priority date: 2019-09-24
Filing date: 2020-09-17
Publication date: 2022-05-03
Also published as: WO2021058360A1; FR3101111A1; JP2022548518A; FR3101111B1; EP4208631A1; KR20220066286A

Abstract

A system (4) for injecting air into the exhaust of a combustion engine (3) is disclosed, comprising: -an air injection device (17), and-a solenoid valve (20), the air injection device (17) comprising a cylinder head (6) and a cylinder head cover (13) comprising a body in which a first air duct (25) is formed; the cylinder head includes a body in which a second air pipe (26) and an exhaust gas pipe (9) are formed; the first air pipe (25) is connected upstream to an air injection pump (19), the first air pipe (25) is connected downstream to the second air pipe (26), the second air pipe (26) is connected downstream to the exhaust gas pipe (9), the solenoid valve (20) is fastened on the cylinder head cover (13) and connected downstream to the first air conduit (25).

Description

Device for injecting air into an exhaust

Technical Field

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 a powertrain comprising such an air injection device and/or such an air injection system. The invention finally relates to a motor vehicle comprising such a drive train and/or such an air injection device and/or such an air injection system.

Background

Internal combustion engines of motor vehicles may have systems for injecting air into the exhaust, also referred to as secondary air injection systems. Injecting pressurized fresh air into the exhaust pipe of a combustion engine causes combustion of some of the residuals in the exhaust pipe. This combustion causes an increase in the exhaust gas temperature upstream of pollution control components (such as catalytic converters, particulate filters, selective catalytic reduction devices). Since these pollution control means are only effective from a certain exhaust gas temperature (e.g. around 400 ℃), integrating the system for injecting air into the exhaust enables to improve its operation. In particular, the system for injecting air into the exhaust when the engine is started makes it possible to accelerate the increase in the temperature of the pollution control member, so as to reach the anti-pollution standard.

The system for injecting air into the exhaust is substantially constituted by an air injection pump which pressurizes the air captured at the outlet of the air filter, a solenoid valve which controls the flow rate of the air and a system for diffusing the air towards the exhaust manifold. These systems include a large number of tubes. As a result, they are heavy and bulky, and their integration into the engine compartment can be cumbersome. In addition, these systems can be easily contaminated. The interface between the bulk of the tubing may also cause leaks. Therefore, systems for injecting air into the exhaust are sometimes not very reliable. Finally, the bulk air tube causes a pressure drop. The pump of the air injection system must therefore be powerful enough to compensate for these pressure drops.

Disclosure of Invention

It is an object of the present invention to provide a device for injecting air into an exhaust which overcomes the above disadvantages and improves the devices known from the prior art.

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

A second subject of the invention is a device for injecting air into an exhaust emission that does not become contaminated easily.

A third subject of the present invention is an apparatus for injecting air into exhaust without causing air leakage or exhaust gas leakage.

A fourth subject of the invention is a device for injecting air into an exhaust causing a minimum pressure drop.

A fifth subject of the invention is a device for injecting air into an exhaust, which is easily accessible for the purpose of possible maintenance interventions.

Summary of the invention

The invention relates to a system for injecting air into the exhaust of a combustion engine, the air injection system comprising:

-means for injecting air into the exhaust, and

-a solenoid valve for controlling the flow of air,

the air injection device includes a cylinder head and a cylinder head cover including a body in which a first air pipe is formed; the cylinder head includes a body in which a second air pipe and a gas discharge pipe are formed; the first air pipe upstream is connectable to an air injection pump, the first air pipe downstream is connected to the second air pipe, the second air pipe downstream is connected to the gas discharge pipe, the solenoid valve is secured against the cylinder head cover, the solenoid valve downstream is connected to the first air pipe.

The air injection system may include a second sealing device between the cylinder head and the cylinder head cover, the second sealing device being capable of preventing air or exhaust gas from leaking from the first air tube or from the second air tube.

The second sealing means may comprise a metal seal.

The cylinder head may include a plurality of gas discharge pipes, and the second air pipe may include a chamber and a plurality of air pipe portions, each air pipe portion being connected upstream to the chamber and each air pipe portion being connected downstream to one of the gas discharge pipes, respectively.

The first air pipe may be arranged vertically above the second air pipe, and the second air pipe may extend the first air pipe, the second air pipe being arranged vertically above the gas discharge pipe, such that condensate formed in the first air pipe or in the second air pipe cannot be trapped in the first air pipe or in the second air pipe.

The cylinder head cover may comprise a fastening interface (interface) for the solenoid valve, which fastening interface comprises third sealing means intended to prevent leakage of air or exhaust gases.

The air injection system may comprise a support for a solenoid valve, said support being fastened directly to the cylinder head cover, the solenoid valve being fastened directly to said support, said support comprising an air collection chamber connected downstream to the first air duct.

The cylinder head cover may include a cutout (cutout) to increase the volume of the air collection chamber.

The air injection system may include a first sealing device between the cylinder head and the cylinder head cover, the first sealing device being capable of preventing oil vapor from leaking to the outside of the cylinder head body, the first sealing device including a resin seal.

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

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

Drawings

These subjects, characteristics and advantages of the invention will be explained in detail in the following description of a particular embodiment, given by way of non-limiting example, with reference to the accompanying drawings, in which:

fig. 1 is a schematic view of a motor vehicle comprising a device for admitting air into an exhaust according to an embodiment of the invention.

Fig. 2 is a cross-sectional side view of a combustion engine equipped with a device for admitting air into an exhaust according to an embodiment of the invention.

Fig. 3 is an isometric perspective view of a cylinder head cover of a device for admitting air into an exhaust.

Fig. 4 is an isometric view from above of the cylinder head cover.

Fig. 5 is an isometric view from below of the cylinder head cover.

Detailed Description

Fig. 1 schematically illustrates a motor vehicle 1 equipped with a powertrain 2 according to an embodiment of the invention. The vehicle 1 may be of any kind. In particular, it may be, for example, a private car, a utility car, a truck or a passenger car. The power train 2 comprises a combustion engine 3 and a system 4 for injecting air into the exhaust gases.

In the following description, upstream and downstream are defined with reference to the natural flow direction of air or exhaust gas. Air or exhaust gas is circulated from upstream to downstream. In addition, the vehicle 1 is considered to be resting on a horizontal ground. The vertical axis Z is represented by a bottom-up oriented vector.

The combustion engine 3 comprises an engine block 5 in which cylinders are formed, which are locations where fuel (e.g. gasoline or diesel) is combusted. There may be any number of cylinders, for example three cylinders, four cylinders, six cylinders or eight cylinders. The combustion engine 3 further comprises a cylinder head 6 fastened to the engine block 5. The cylinder head 6 is the part of the combustion engine closing the top of the cylinder. The cylinder head 6 houses or supports in particular air intake valves, exhaust valves 7 and a camshaft 8 mechanically connected to the intake and exhaust valves 7. The discharge valve is a mechanical member that separates each of the cylinders from the gas discharge pipe 9. The gas discharge pipe 9 is a passage formed in the cylinder head for discharging discharge gas (i.e., gas resulting from combustion of fuel in the cylinder). The cylinder head may comprise as many individual gas discharge pipes 9 as there are cylinders. Each gas discharge pipe delivers exhaust gas from the cylinder to the outside of the cylinder head.

The power train also comprises an exhaust device comprising an exhaust manifold 10, for example fastened against the cylinder head at the outlet of the gas exhaust pipe 9. The exhaust manifold may include as many inlets as there are gas exhaust pipes, and a single outlet. It is connected downstream to a discharge pipe 11, which is itself connected downstream to a pollution control element 12. The pollution control component may be, for example, a catalytic converter, a particulate filter, a selective catalytic reduction device (also referred to as an SCR device), or any other component capable of purifying or reducing the particulate content of the exhaust gas. The pollution control means may require that the exhaust gas reach a temperature threshold (e.g. a threshold of about 400 ℃) in order to operate in an optimal manner.

The combustion engine 3 further comprises a cylinder head cover 13. The cylinder head cover is the upper part of the combustion engine 3 that covers the cylinder head 6. As shown in fig. 2, the head cover 13 may be mounted to vertically rest on the cylinder head 6. A substantially horizontal plane P1 may vertically separate the head cover 13 from the cylinder head 6. The cylinder head 6 may comprise two lower half-bearings 14 and the cylinder head cover 13 may comprise 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 inner volume 16 in which in particular the camshaft 8 and the valve 7 can be arranged. Oil in the form of vapor or droplets may be located in the interior volume 16 to lubricate various moving elements of the combustion engine, in particular to lubricate the camshaft and valves.

The cylinder head and the cylinder head cover may be a one-piece component. They may be made of metal. They may be obtained by machining and/or casting. The cylinder head cover is fastened in a sealing manner to the cylinder head, for example by means of fastening screws. As seen in fig. 3, 4 and 5, the cylinder head and the cylinder head cover may further include: reinforcement ribs, openings intended to receive, for example, injectors and/or spark plugs.

The system 4 for injecting air into the exhaust includes 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. The air filter 18 is connected downstream to an air injection pump 19 via a first outer tube 21. The air injection pump 19 is connected downstream to the solenoid valve 20 through a second outer tube 22.

The air filter 18 is a member capable of drawing out fresh air from the outside and filtering the fresh air. In particular, the air filter may filter suspended particles in the air in order to prevent them from further entering the system for injecting air into the exhaust. The air filter 18 may also be used to filter fresh air supplied to the cylinders via the intake pipe in order to allow fuel to burn.

The air injection pump 19, or more simply the air pump 19, is a pump capable of pressurizing air from the air filter 18. The air injection pump may be electrically connected to the source of electrical energy and to the electronic control unit. The activation of the air injection pump 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 therethrough. It may comprise a connector electrically connected to the electronic control unit. The control commands issued by the electronic control unit enable the air flow rate through the solenoid valve to be controlled. The solenoid valve is fastened to the cylinder head cover 13 by a support 23. The support 23 is directly fastened (e.g., screwed) to the cylinder head cover, and the solenoid valve is directly fastened (e.g., screwed) to the support 23. The support 23 is fastened to a fastening interface 24 of the cylinder head cover, which is clearly visible in fig. 4. The solenoid valve is thus held firmly against the combustion engine 3 without overhang. This fastening of the solenoid valve is particularly reliable and resistant to vibrations. The support 23 comprises an air collection chamber connected downstream to the air injection means 17. The support 23 may also comprise a channel upstream connecting the air collection chamber and downstream connecting the air injection device 17, in particular to a first air duct 25 formed in the cylinder head cover. As a variant, the support 23 and the cylinder head cover may form only a single part. In other words, the solenoid valve may be fastened directly to the cylinder head cover.

The cylinder head cover may also include cutouts to save material and increase the volume of the collection chamber. The cut-out may advantageously be positioned below the solenoid valve 20.

The air injection device 17, i.e. the part of the system 4 for injecting air into the exhaust gases formed in the combustion engine block, will now be described in more detail.

The cylinder head cover 13 includes a body in which a first air pipe 25 is formed. Similarly, the cylinder head comprises a body in which the second air pipe 26 and the gas discharge pipe 9 are formed. The first air duct 25 and the second air duct are thus cutouts realized in the body of the head cover 13 and in the body of the cylinder head 6, respectively. The first air tube 25 is connected downstream (i.e., docked) to the second air tube 26. The second air pipe 26 is connected downstream to the gas discharge pipe 9.

The first air duct 25 thus includes an inlet that may be disposed on an upper surface of the head cover and an outlet that may be disposed on a lower surface of the head cover, the lower surface being in contact with the cylinder head 6. By following the first air duct from its inlet to its outlet, i.e. from upstream to downstream, it can be seen that it follows a downward or even locally horizontal trajectory.

Similarly, the second air tube 26 includes an inlet disposed on an upper surface of the cylinder head and an outlet that may be disposed on a side surface of the cylinder head. By following the second air duct from its inlet to its outlet, i.e. from upstream to downstream, it can be seen that it also follows a downward or even locally horizontal trajectory.

The first air pipe 25 is arranged above the second air pipe 26. The second air pipe extends the first air pipe 25 and is arranged above the gas discharge pipe 9. Thus, the liquid or condensate formed in the first air pipe cannot be retained there and is drained under gravity to the second air pipe. Similarly, the liquid or condensate formed in the second air pipe cannot stay there and drain under gravity towards the gas discharge pipe 9. In other words, neither the first air tube 25 nor the second air tube 26 includes a low point that forms a stagnant volume of liquid. The first and second air tubes may be oriented as vertically as possible to promote the flow of any liquid or condensate under gravity to the drain.

With reference to fig. 1, 2 and 5, the assembly formed by the cylinder head and the cylinder head cover comprises a first sealing device 31 and a second sealing device 32, both of which are arranged between the cylinder head and the cylinder head cover along a plane P1. The first sealing means can prevent oil vapor from leaking to the outside of the assembly formed by the cylinder head and the cylinder head cover. The first sealing means may be arranged around the inner volume 16, in which the lubricating oil may be pressurized. The second sealing device can prevent air or exhaust gas from leaking from the first air pipe or the second air pipe of the air injection device. The second sealing device is disposed around an interface formed between the first air tube and the second air tube. It may have a shape substantially reproducing the cross-sectional shape of the first air tube and the second air tube, e.g. substantially circular or substantially rectangular.

The two sealing means are thus subject to different constraints. The first device is designed to withstand an environment filled with lubricating oil and the second device is designed to withstand pressurized air from upstream or high temperature exhaust gas from the gas exhaust pipe 9 which may occasionally occur in the upstream direction. Advantageously, the first sealing means 31 may comprise a resin seal. The second sealing means may comprise a metal seal. In a variant embodiment, the air injection means may comprise a single sealing means that is resistant to oil, to pressurized air and to exhaust gases at the same time. The single sealing means may be, for example, a metal seal. However, a single sealing device is more complex and expensive to implement than two separate sealing devices of different kinds.

With reference to fig. 4, the housing cover further comprises third sealing means 33 arranged on the fastening interface 24 of the support 23 for holding the solenoid valve 20. In a manner similar to the second sealing means, the third sealing means 33 is designed to withstand pressurized air from upstream or exhaust gases from the gas exhaust pipe 9 which may occasionally occur in the upstream direction. The third sealing means may comprise a metal seal.

The system for injecting air into an exhaust thus formed enables air ducts to be saved compared to systems for injecting air into an exhaust known in the prior art. Specifically, with the system according to the invention, no pipe needs to be provided between the solenoid valve 20 and the cylinder head cover. This saves space in the engine compartment where the combustion engine is located. In addition, the line formed by the

air pipes

25 and 26 contributes to the lightening of the combustion engine.

Referring to fig. 2, the combustion engine 3 may be positioned a short distance from the hood 34 of the vehicle. The solenoid valve may be positioned to be accessible directly under the hood 34 of the vehicle. Thus making its maintenance and/or possible replacement easier.

When the combustion engine is running, fresh air is drawn in from the outside by the air injection pump. This fresh air enters the system 4 for injecting air into the exhaust through the air filter 18, then passes through the first outer pipe 21, and then the air injection pump 19. This air is pressurized by the air injection pump 19, passes through the second outer tube 22 and then reaches the solenoid valve 20. The flow rate of air 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 injection device at the cylinder head cover 13. By means of the third sealing means 33 no air or exhaust gas leakage occurs at the interface between the support 23 and the cylinder head cover. This air then passes through a first air pipe 25 and reaches a second air pipe 26 integrated in the cylinder head. By means of the second sealing device 32, no air or exhaust gas leakage occurs at the interface between the first air tube and the second air tube. The air then reaches the chamber 27 from where it is distributed into the air duct portion 28. This air is then injected into the gas discharge pipe 9 as close as possible to the discharge valve 7. This path of the air from the outside and away from the gas discharge pipe provides a low pressure drop and good distribution uniformity in the various gas discharge pipes 9. The air mixed with the exhaust gases thus allows the residues present in the exhaust gases to burn. The temperature of the exhaust gases can thus rise rapidly as soon as the combustion engine is started. The exhaust gases are subsequently discharged from the combustion engine 3 through an exhaust manifold 10, an exhaust pipe 11 and a pollution control element 12. Since the exhaust gas has reached a high temperature, the pollution control member can be operated in an optimal manner. The exhaust gas thus treated can then be discharged from the vehicle. When condensate forms in the system for injecting air into the exhaust, it is directed under gravity to the gas exhaust pipe 9. Thus, condensate cannot be trapped or accumulate in one of the pipes of the system for injecting air into the exhaust. In parallel with this operation, the various moving members within the cylinder head 6 may be lubricated with pressurized oil. By means of the first sealing means 31, pressurized oil cannot escape through the interface between the head cover and the cylinder head.

Claims

1. A system (4) for injecting air into the exhaust of a combustion engine (3), characterized in that it comprises:

-air injection means (17), and

-a solenoid valve (20),

the air injection device (17) includes a cylinder head (6) and a head cover (13) including a body in which a first air tube (25) is formed; the cylinder head comprises a body in which a second air tube (26) and a gas discharge tube (9) are formed; the first air pipe (25) is connectable upstream to an air injection pump (19), the first air pipe (25) is connected downstream to the second air pipe (26), the second air pipe (26) is connected downstream to the gas discharge pipe (9), the solenoid valve (20) is secured against the cylinder head cover (13), the solenoid valve (20) is connected downstream to the first air pipe (25).

2. The air injection system (4) according to the preceding claim, characterized in that it comprises a second sealing device (32) between the cylinder head (6) and the cylinder head cover (13) which is able to prevent air or exhaust gas from leaking from the first air duct or from the second air duct.

3. The air injection system (4) according to the preceding claim, wherein the second sealing means (32) comprises a metal seal.

4. The air injection system (4) according to one of the preceding claims, characterized in that the cylinder head (6) comprises a plurality of gas discharge pipes (9) and in that the second air pipe (26) comprises a chamber (27) and a plurality of air pipe portions (28), each air pipe portion (28) being connected upstream to said chamber (27) and each air pipe portion being connected downstream to one of the gas discharge pipes (9), respectively.

5. The air injection system (4) according to one of the preceding claims, characterized in that the first air pipe (25) is arranged vertically above the second air pipe (26), and in that the second air pipe (26) extends the first air pipe (25), the second air pipe (26) being arranged vertically above the gas discharge pipe (9), so that condensate formed in the first air pipe (25) or in the second air pipe (26) cannot remain in the first air pipe or in the second air pipe.

6. The air injection system (4) as claimed in one of the preceding claims, characterized in that the cylinder head cover (13) comprises a fastening interface (24) for the solenoid valve (20), which fastening interface (24) comprises third sealing means (33) which are intended to prevent leakage of air or exhaust gases.

7. The air injection system (4) as claimed in one of the preceding claims, characterized in that it comprises a support (23) for a solenoid valve, said support (23) being fastened directly to the cylinder head cover (13), the solenoid valve (20) being fastened directly to said support (23), said support comprising an air collection chamber connected downstream to the first air duct (25).

8. The air injection system (4) according to the preceding claim, characterized in that the cylinder head cover comprises a cut-out in order to increase the volume of the air collection chamber.

9. The air injection system (4) of one of the preceding claims, comprising a first sealing means (31) between the cylinder head (6) and the cylinder head cover (13), the first sealing means being capable of preventing oil vapour from leaking outside the cylinder head body (6), the first sealing means (31) comprising a resin seal.

10. A powertrain (2), characterized in that it comprises a combustion engine (3), which combustion engine (3) comprises an air injection system (4) according to one of the preceding claims.

11. A motor vehicle (1) characterised in that it comprises an air injection system (4) according to one of the preceding claims, and/or a powertrain (2) according to one of the preceding claims.