JP7592071B2 - Device for injecting air into the exhaust - Google Patents

Description

The invention relates to an apparatus 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 including such an air injection device and/or such an air injection system. The invention finally relates to a motor vehicle including such a powertrain and/or such an air injection device and/or such an air injection system.

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. The injection of pressurized fresh air into the exhaust pipe of the combustion engine causes certain residues to burn in the exhaust pipe. This combustion increases the temperature of the exhaust gases upstream of the pollution control elements, such as catalytic converters, particulate filters, selective catalytic reduction devices, etc. Since these pollution control elements are only effective at certain exhaust gas temperatures (for example around 400°C), their operation can be improved by integrating a system for injecting air into the exhaust. In particular, a system for injecting air into the exhaust during engine start-up allows the temperature rise of the pollution control elements to be accelerated and pollution control standards to be met.

Systems for injecting air into the exhaust generally consist of an air injection pump that pressurizes the air captured at the outlet of the air filter, a solenoid valve that controls the flow rate of the air, and a system that diffuses the air towards the exhaust manifold. These systems consist of a large number of tubes. Therefore, these systems are heavy and bulky, and it can be difficult to integrate these systems in the engine compartment. Furthermore, these systems can easily become dirty. The interfaces between the multiple tubes can also develop leaks. Therefore, systems for injecting air into the exhaust can be unreliable. Finally, the large number of air tubes causes pressure drops. Therefore, the pump of the air injection system must be powerful enough to compensate for these pressure drops.

PRESENTATION OF THE INVENTIVE EMBODIMENT The object of the present invention is to provide a device for injecting air into an exhaust gas, which overcomes the above mentioned drawbacks and improves on the devices known from the prior art.

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

The second subject of the present invention is a device for injecting air into the exhaust so that it does not easily become dirty.

The third subject of the invention is a device for injecting air into the exhaust without causing air or exhaust gas leaks.

The fourth subject of the invention is a device for injecting air into the exhaust, which creates a minimal pressure drop.

The fifth subject of the invention is a device for injecting air into the exhaust, easily accessible for the purpose of possible intervention for repairs.

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 gas;
- a solenoid valve;
Equipped with
The air injection device includes a cylinder head and a cylinder head cover, the cylinder head cover includes a main body having a first air pipe formed therein, the cylinder head includes a main body having a second air pipe and a gas exhaust pipe formed therein, the first air pipe is connectable to an air injection pump on an upstream side , the first air pipe is connected to a second air pipe on a downstream side , the second air pipe is connected to a gas exhaust pipe on a downstream side , a solenoid valve is fixed to the cylinder head cover, and the solenoid valve is connected to the first air pipe on a downstream side .

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 leakage of air or exhaust gas from the first air pipe or the second air pipe.

The second sealing device may include a metal seal.

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

The first air pipe may be disposed vertically above the second air pipe, and the second air pipe may be an extension of the first air pipe, and the second air pipe is disposed vertically above the gas exhaust pipe such that condensation formed in the first air pipe or the second air pipe cannot stagnate in the first air pipe or the second air pipe.

The cylinder head cover may be provided with 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 a solenoid valve, said support being fixed directly to the cylinder head cover, and said solenoid valve being fixed directly to said support, said support including an air collection chamber connected downstream to the first air pipe.

The cylinder head cover may have a 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 leakage of oil vapor outside the cylinder head body, the first sealing device including a resin seal.

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

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

These objects, 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 attached figures.

1 is a schematic diagram of a motor vehicle including a device for admitting air to an exhaust according to an embodiment of the present invention; 1 is a side view in cross section of a combustion engine equipped with a device for admitting air into the exhaust according to an embodiment of the present invention; FIG. 2 is an isometric view of the cylinder head cover of the device for injecting air into the exhaust. FIG. 2 is a top isometric view of the cylinder head cover. FIG. 2 is an isometric view from below of the cylinder head cover.

Figure 1 shows a schematic representation of a motor vehicle 1 with a powertrain 2 according to an embodiment of the present invention. The vehicle 1 can be of any type. In particular, the vehicle 1 can be, for example, a car, a utility vehicle, a truck or a 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 the air or exhaust gases. The air or exhaust gases circulate 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 the cylinders are formed, which are the places of combustion of a fuel, for example gasoline or diesel. The cylinders can be any number, for example 3 cylinders, 4 cylinders, 6 cylinders, 8 cylinders, etc. The combustion engine 3 also comprises a cylinder head 6 fixed to the engine block 5. The cylinder head 6 is a component of the combustion engine that closes the top of the cylinders. The cylinder head 6 houses or supports, among other things, the intake valves, the exhaust valves 7, as well as the camshaft 8 that is mechanically connected to the intake and exhaust valves 7. The exhaust valves are mechanical members that separate each cylinder from the gas exhaust pipes 9. The gas exhaust pipes 9 are channels formed in the cylinder head for the discharge of exhaust gases, i.e. gases resulting from the combustion of the fuel in the cylinders. The cylinder head may include as many separate gas exhaust pipes 9 as there are cylinders. Each gas exhaust pipe carries the 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 relative to the cylinder head at the outlet of the gas exhaust pipe 9. The exhaust manifold may comprise as many inlets as there are gas exhaust pipes and a single outlet. The exhaust manifold is connected downstream of an exhaust pipe 11, which is itself connected downstream of a pollution prevention member 12. The pollution prevention member may be, for example, a catalytic converter, a particulate filter, a selective catalytic reduction device (also called SCR device) or any other member capable of disinfecting or reducing the content of particles in the exhaust gases. The pollution prevention 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.

The 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 mounted so as to rest vertically on the cylinder head 6. A substantially horizontal plane P1 may vertically separate the cylinder head cover 13 from the cylinder head 6. The cylinder head 6 may include two lower half bearings 14 and the cylinder head cover 13 may include two upper half bearings 15. The two lower half bearings 14 cooperate with the two upper half bearings 15 to form two bearings supporting 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 camshafts 8 and the valves 7 may be located in particular. Oil in the form of vapor or droplets may be placed in this internal volume 16 to lubricate the various moving elements of the combustion engine, in particular the camshafts and the valves.

The cylinder head and the cylinder head cover can be one integral component. They may be made of metal. They 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 fastening screws. As can be seen in figures 3, 4 and 5, the cylinder head and the cylinder head cover can also include reinforcing ribs, openings, for example intended to receive injectors and/or spark plugs.

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

The air filter 18 is a member capable of drawing and filtering fresh air from the outside. In particular, the air filter 18 can filter particles suspended in the air to prevent them from further entering the system for injecting air into the exhaust. The air filter 18 can also serve to filter the fresh air supplied to the cylinders via the intake pipe to enable the combustion of fuel.

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

The solenoid valve 20 is a member that can control the flow rate of air passing through it. The solenoid valve 20 may include a connector electrically connected to an electronic control unit. The electronic control unit issues a control command that can control the flow rate of air passing through the solenoid valve. The solenoid valve 20 is fixed to the cylinder head cover 13 via a support 23. The support 23 is fixed, for example screwed, directly to the cylinder head cover and the solenoid valve is fixed, for example screwed, directly to the support 23. The support 23 is fixed to a fixing 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 overhanging. Such a fixing of the solenoid valve is particularly reliable and vibration-resistant. The support 23 is provided with an air collection chamber connected downstream to the air injection device 17. The support 23 may also include a channel connected upstream to the air collection chamber and downstream to the air injection device 17, in particular to a first air pipe 25 formed in the cylinder head cover. As a variant, the support 23 and the cylinder head cover may form only one component, in other words the solenoid valve may be fixed directly to the cylinder head cover.

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

The air injection device 17, i.e., 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 comprises a body in which a first air pipe 25 is formed. Similarly, the cylinder head comprises a body in which a second air pipe 26 and a gas exhaust pipe 9 are formed. The first air pipe 25 and the second air pipe are thus cut-outs realized in the body of the cylinder head cover 13 and the body of the cylinder head 6, respectively. The first air pipe 25 is connected downstream (i.e. butted) to the second air pipe 26. The second air pipe 26 is connected downstream to the gas exhaust pipe 9.

The first air pipe 25 thus comprises an inlet which may be located on the upper surface of the cylinder head cover and an outlet which may be located 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 pipe from the inlet to the outlet, i.e. from upstream to downstream, it can be seen that the first air pipe follows a downward or locally horizontal trajectory.

Similarly, the second air pipe 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. By following the second air pipe from inlet to outlet, i.e. from upstream to downstream, it can also be seen that the second air pipe follows a downward or locally horizontal trajectory.

The first air pipe 25 is disposed above the second air pipe 26. The second air pipe extends the first air pipe 25 and is disposed above the gas exhaust pipe 9. Thus, any liquid or condensate formed in the first air pipe cannot stagnate there and is discharged under gravity toward the second air pipe. Similarly, any liquid or condensate formed in the second air pipe cannot stagnate there and is discharged under gravity toward the gas exhaust pipe 9. In other words, neither the first air pipe 25 nor the second air pipe 26 includes a low point that forms a liquid retention volume. The orientation of the first air pipe and the second air pipe can be as vertical as possible to promote the flow of any liquid or condensate under gravity toward the exhaust pipe.

1, 2 and 5, the assembly formed by the cylinder head and the cylinder head cover includes 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 the plane P1. The first sealing device can prevent oil vapor from leaking outside the assembly formed by the cylinder head and the cylinder head cover. The first sealing device can be arranged around the internal volume 16 in which the lubricating oil can 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 arranged around the interface formed between the first air pipe and the second air pipe. The second sealing device can have a shape that substantially reproduces the shape of the cross section of the first air pipe and the second air pipe, for example, a substantially circular or substantially rectangular shape.

The two sealing devices are therefore subject to different constraints: the first device is designed to withstand a lubricant-laden environment, the second device is designed to withstand pressurized air coming from upstream, or possibly hot exhaust gases rising sporadically in the upstream direction from the gas exhaust pipe 9. Advantageously, the first sealing device 31 may comprise a plastic seal. The second sealing device may comprise a metal seal. In a variant embodiment, the air injection device may comprise 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 sealing device is more complex and expensive to implement than two separate sealing devices of different types.

Referring 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 rising sporadically in the upstream direction from the gas exhaust pipe 9. The third sealing device may comprise a metal seal.

The system for injecting air into the exhaust thus formed makes it possible to save air pipes compared to systems for injecting air into the exhaust known from the prior art. In particular, in the system of the invention, no piping is required between the solenoid valve 20 and the cylinder head cover. This saves space in the engine compartment in which the combustion engine is located. Furthermore, the piping line formed by the air pipes 25 and 26 helps to make the combustion engine lighter.

With reference to FIG. 2, the combustion engine 3 may be located at a short distance from the vehicle bonnet 34. The solenoid valve may be positioned so that it is accessible directly under the vehicle bonnet 34. Thus, maintenance and/or possible replacement thereof is facilitated.

During operation of the combustion engine, fresh air is sucked in from the outside by the air injection pump. The fresh air enters the system 4 for injecting air into the exhaust via the air filter 18, then passes through the first external pipe 21 and then through the air injection pump 19. The air is pressurized by the air injection pump 19, passes through the second external pipe 22 and then reaches the solenoid valve 20. Depending on the state of the solenoid valve controlled by the electronic control unit, the flow rate of air through the solenoid valve 20 can be adjusted. The air then passes through the support 23 and then reaches the air injection device of the cylinder head cover 13. The third sealing device 33 ensures that no air or exhaust gas leakage occurs at the interface between the support 23 and the cylinder head cover. The air then passes through the first air pipe 25 and reaches the second air pipe 26, which is integrated into the cylinder head. The second sealing device 32 ensures that no air or exhaust gas leakage occurs at the interface between the first and second air pipes. The air then arrives at the chamber 27, from where it is distributed to the air pipe section 28. The air is then injected into the gas exhaust pipe 9 as close as possible to the exhaust valve 7. The route of the air from the outside to the gas exhaust pipe provides a low pressure drop in the various gas exhaust pipes 9 and good uniformity of distribution. The air thus mixed with the exhaust gases allows the combustion of residues present in the exhaust gases. Thus, as soon as the combustion engine starts, the temperature of the exhaust gases can rise quickly. The exhaust gases are then discharged from the combustion engine 3 and pass through the exhaust manifold 10, the exhaust pipe 11 and the pollution prevention member 12. Due to the high temperature of the exhaust gases, the pollution prevention member works optimally. The exhaust gases thus treated can then be discharged from the vehicle. If condensate forms in the system for injecting air into the exhaust, it is directed under gravity towards the gas exhaust pipe 9. Thus, the condensate cannot stagnate or accumulate in one of the pipes of the system for injecting air into the exhaust. In parallel with this operation, the various moving parts in the cylinder head 6 can be lubricated with pressurized oil. The first sealing device 31 prevents pressurized oil from escaping through the interface between the cylinder head cover and the cylinder head.

Claims (10)

An air injection system (4) for injecting air into the exhaust of a combustion engine (3), comprising:
An air injection device (17);
A solenoid valve (20);
Equipped with
The air injection device (17) includes a cylinder head (6) and a cylinder head cover (13), the cylinder head cover includes a body in which a first air pipe (25) is formed, the cylinder head includes a body in which a second air pipe (26) and a gas exhaust pipe (9) are formed, the first air pipe (25) can be connected upstream to an air injection pump (19), the first air pipe (25) is connected downstream to the second air pipe (26), and the second air pipe (26) is connected downstream to the gas exhaust pipe (9). a first air pipe (25) connected downstream to said chamber (27), said solenoid valve (20) being fixed to said cylinder head cover (13), said solenoid valve (20) being connected downstream to a first air pipe (25) , said cylinder head (6) including a plurality of gas exhaust pipes (9), said second air pipe (26) including a chamber (27) and a plurality of air pipe sections (28), each of said air pipe sections (28) being connected upstream to said chamber (27), each of said air pipe sections being connected downstream to one of said gas exhaust pipes (9).
2. An air injection system (4). The air injection system (4) according to claim 1, further comprising a second sealing device (32) between the cylinder head (6) and the cylinder head cover (13), the second sealing device being capable of preventing leakage of air or exhaust gas from the first air pipe or the second air pipe. The air injection system (4) of claim 2, characterized in that the second sealing device (32) includes a metal seal. 4. An air injection system (4) according to any one of claims 1 to 3, characterized in that the first air pipe (25) is arranged vertically above the second air pipe (26), the second air pipe (26) being an extension of the first air pipe (25), the second air pipe (26) being arranged vertically above the gas exhaust pipe (9) so that condensate formed in the first air pipe (25) or the second air pipe (26) cannot stagnate in the first air pipe or the second air pipe. 5. The air injection system (4) according to claim 1, characterized in that the cylinder head cover ( 13 ) comprises a fixed interface (24) for the solenoid valve (20), the fixed interface (24) including a third sealing device (33) intended to prevent leakage of air or exhaust gases. 6. An air injection system (4) according to any one of claims 1 to 5, characterized in that it comprises a support (23) for a solenoid valve, said support (23) being fixed directly to said cylinder head cover (13), said solenoid valve (20) being fixed directly to said support (23), said support including an air collection chamber connected downstream to said first air pipe ( 25 ). 7. Air injection system (4) according to claim 6 , characterized in that the cylinder head cover comprises a cutout for increasing the volume of the air collection chamber. 8. The air injection system (4) according to claim 1, further comprising a first sealing device (31) between the cylinder head (6) and the cylinder head cover (13), the first sealing device being capable of preventing leakage of oil vapor outside the body of the cylinder head ( 6 ), the first sealing device (31) including a resin seal. A powertrain (2) comprising a combustion engine (3), characterized in that said combustion engine (3) is equipped with an air injection system (4) according to any one of the claims 1 to 8 . Motor vehicle (1), characterized in that it comprises an air injection system (4) according to any one of claims 1 to 8 and/or a powertrain (2) according to claim 9 .

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