GB2493326A

GB2493326A - An exhaust gas recirculation valve

Info

Publication number: GB2493326A
Application number: GB1110955.0A
Authority: GB
Inventors: Fiorello Losano
Original assignee: GM Global Technology Operations LLC
Current assignee: GM Global Technology Operations LLC
Priority date: 2011-08-02
Filing date: 2011-08-02
Publication date: 2013-02-06
Anticipated expiration: 2031-08-02
Also published as: GB201110955D0; GB2493326B

Abstract

Disclosed is an exhaust gas recirculation (EGR) valve assembly for selectively opening or closing exhaust gas flow. The valve assembly may be used to control the flow of exhaust gas from a source, such as an exhaust manifold 225, to an EGR cooler 310 or to an EGR cooler bypass passage 310a or both. The valve arrangement comprises a single by-pass valve 320a and a housing 1 having inlet F1 for the exhaust gas, a first outlet F2 connected to the EGR cooler passage 310 and a second outlet F3 connected to the EGR cooler bypass passage 310a. The single by-pass valve comprises at least a shut-off member 2, possibly in the form a piston having a shaft 3 and a head 4 which may be slid to at least partially cover either the first or second outlets or moved to a position in which it covers neither outlet.

Description

SIMPLIFIED EGR VALVE ASSEMBLY

*. *.*

Technical Field

The present invention relates to a simplified exhaust gas recirculation (EGR) valve assembly and, in particular, to a by-pass valve for selectively open or close exhaust gas flow from exhaust manifold to EGR cooler, to EGR cooler bypass passage or both.

Background

Internal combustion engine (ICE) , the modern multi-valve, high compression engine can create NOx (Nitrogen Oxides) during the high temperature combustion process. In order to prevent the formation of I'JOx the internal combustion engine is provided with Exhaust Gas Recirculation (EGR) valves.

Usually, an engine recirculates exhaust gas by piping it from the exhaust manifold to the intake manifold and a control valve within the circuit regulates and times the gas flow.

The EGR valve, or Exhaust Gas Recirculation valve, is a controlled valve which allows a specific amount of exhaust gas back into the intake manifold. This exhaust mixes with the intake air and actually cools the combustion process, thus preventing the formation of Nitrogen related gases.

As a matter of fact EGR was developed to reduce the combustion temperatures to below 2,500 degrees, the threshold where NOx is created.

The EGR system are provided also with an EGR cooler used for cooling the exhaust gases and with an EGR cooler bypass to avoid overcooling.

Conventional EGR system comprises two valves acting on two different gas paths. In particular a first valve allows flowing the recirculating exhaust gases from exhaust manifold to the EGR cooler and a second valve control the flowing of EGR gases through the EGR cooler bypass.

Therefore is know in the art that the EGR system is provided with two separate valves, the EGR valve and EGR cooler bypass.

The use of two separate valves for controlling the gas flowing either to the EGR cooler or to the EGR cooler bypass involve high number of components, two valves and relative mechanism to manage and high costs.

An object of an embodiment of the present invention is to solve the above mentioned problems and to provide a single valve that can allow alone to manage the flow from exhaust manifold to EGR cooler, to EGR cooler bypass passage or both.

Another object of an embodiment of the present invention is to provide a single valve functional for selectively close, open or regulate the exhaust gas flow trough the EGR cooler, the EGR cooler bypass or both.

Another object of an embodiment of the present invention is to provide a single simplified valve with better function and durability, less costly and easy to install.

Summary

These objects are achieved by means of an embodiment of the present invention, which relates to an exhaust gas recirculation (EGR) valve assembly comprising a single by-pass valve, said single by-pass valve comprising at least a shut-off member and a housing provided with at least one inlet opening, at least a first outlet opening, at least a second outlet opening, said inlet opening being connected to a source of exhaust gases, e.g. an exhaust gas manifold, said first opening being connected to a cooler by-pass and said second outlet opening being connected to an EGR cooler.

According to an exemplary embodiment, the shut-off member can slide in said housing selectively closing at least said inlet opening or at least one of said outlet openings.

According to an aspect of the invention, the shut-off member can slide in said housing partially closing at least said inlet opening or at least said first outlet opening for metering the flow.

According to a further aspect of the invention, the shut-off member slides in said housing following a linear path.

According to a further exemplary embodiment, the by-pass valve is integrated at the inlet end of the EGR cooler.

According to a further exemplary embodiment, the EGR cooler is integrated in the intake manifold.

According to a common aspect of the embodiments the shut-off member comprises at least a head element and at least a shaft element, said head element having a cylindrical shape.

Brief Description of the Drawings

Further advantages and features of an embodiment of the present invention will be more apparent from the

description below, provided with reference to the

accompanying drawings, purely by way of a non-limiting

example, wherein:

-Figure 1 shows a top view of an automotive system; -Figure 2 shows a side view of an automotive system; -Figure 3 shows a schematic top view of a simplified ECR valve assembly according to an exemplary embodiment of the invention; and -Figures 4a-4d show a schematic sectional view of a single by-pass valve with relative working positions mounted in a simplified EGR valve assembly according to an exemplary embodiment of the invention.

Detailed Description

Some embodiments may include an automotive system 100, as shown in Figures 1 and 2, that includes an internal combustion engine (ICE) 110 having an engine block 120 defining at least one cylinder 125 having a piston 140 coupled to rotate a crankshaft 145. A cylinder head 130 cooperates with the piston 140 to define a combustion chamber 150. A fuel and air mixture (not shown) is disposed in the combustion chamber 150 and ignited, resulting in hot expanding exhaust gasses causing reciprocal movement of the piston 140. The fuel is provided by at least one fuel injector 160 and the air through at least one intake port 210. The fuel is provided at high pressure to the fuel injector 160 from a fuel rail 170 in fluid communication with a high pressure fuel pump 180 that increase the pressure of the fuel received a fuel source 190. Each of the cylinders 125 has at least two valves 215, actuated by a camshaft 135 rotating in time with the crankshaft 145.

The valves 215 selectively allow air into the combustion chamber 150 from the port 210 and alternately allow exhaust gases to exit through a port 220. In some examples, a cam phaser 155 may selectively vary the timing between the camshaft 135 and the crankshaft 145.

The air may be distributed to the air intake port(s) 210 through an intake manifold 200. An air intake duct 205 may provide air from the ambient environment to the intake manifold 200. In other embodiments, a throttle body 330 may be provided to regulate the flow of air into the manifold 200. In still other embodiments, a forced air system such as a turbocharger 230, having a compressor 240 rotationally coupled to a turbine 250, may be provided.

Rotation of the compressor 240 increases the pressure and temperature of the air in the duct 205 and manifold 200.

An intercooler 260 disposed in the duct 205 may reduce the temperature of the air. The turbine 250 rotates by receiving exhaust gases from an exhaust manifold 225 that directs exhaust gases from the exhaust ports 220 and through a series of vanes prior to expansion through the turbine 250. The exhaust gases exit the turbine 250 and are directed into an exhaust system 270. This example shows a variable geometry turbine (VGT) with a VGT actuator 290 arranged to move the vanes to alter the flow of the exhaust gases through the turbine 250. In other embodiments, the turbocharger 230 may be fixed geometry and/or include a waste gate.

The exhaust system 270 may include an exhaust pipe 275 having one or more exhaust aftertreatrnent devices 280. The aftertreatrnent devices may be any device configured to change the composition of the exhaust gases. Some examples of aftertreatment devices 280 include, but are not limited to, catalytic converters (two and three way) , oxidation catalysts, lean NOx traps, hydrocarbon adsorbers, selective catalytic reduction (SCR) systems, and particulate filters.

Other embodiments may include an exhaust gas recirculaticn (EGR) system 300 coupled between the exhaust manifold 225 and the intake manifold 200. The EGR system 300 may include an EGR cooler 310 to reduce the temperature of the exhaust gases in the EGR system 300. An EGR valve 320 regulates a flow of exhaust gases in the EGR system 300.

The automotive system 100 may further include an electronic control unit (ECU) 450 in communication with one or more sensors and/or devices associated with the ICE 110. The ECU 450 may receive input signals from various sensors configured to generate the signals in proportion to various physical parameters associated with the ICE 110. The sensors include, but are not limited to, a mass airflow and temperature sensor 340, a manifold pressure and temperature sensor 350, a combustion pressure sensor 360, coolant and oil temperature and level sensors 380, a fuel rail pressure sensor 400, a cam position sensor 410, a crank position sensor 420, exhaust pressure and temperature sensors 430, an EGR temperature sensor 440, and an accelerator pedal position sensor 445. Furthermore, the ECU 450 may generate output signals to various control devices that are arranged to control the operation of the ICE 110, including, but not limited to, the fuel injectors 160, the throttle body 330, the EGR Valve 320, the VGT actuator 290, and the cam phaser 155. Note, dashed lines are used to indicate communication between the ECU 450 and the various sensors and devices, but some are omitted for clarity.

Turning now to the ECU 450, this apparatus may include a digital central processing unit (CPU) in communication with a memory system and an interface bus. The CPU is configured to execute instructions stored as a program in the memory system, and send and receive signals to/from the interface bus. The memory system may include various storage types including optical storage, magnetic storage, solid state storage, and other non-volatile memory. The interface bus may be configured to send, receive, and modulate analog and/or digital signals to/from the various sensors and control devices. The program may embody the methods disclosed herein, allowing the CPU to carryout out the steps of such methods and control the ICE 110.

Figure 3 shows a schematic view of an EGR system assembly with a single simplified EGR bypass valve 320a to manage the flow from an exhaust gases source, e.g. an exhaust manifold 225 to EGR cooler 310, to EGR cooler bypass 3lOa or both. In the internal combustion engine (ICE) exhaust gases from exhaust manifold 225 are directed through the EGR cooler 310 and/or to the ECR cooler bypass 310a by means cf a simplified single EGR by-pass valve 320a and subsequently delivered to an intake manifold 200.

Said single EGR by-pass valve 320a substitutes the functions of two valves commonly used i-n conventional ICE.

As a matter of fact in known ICE a first valve opens or closes the passage of the gas flow from the exhaust manifold to the EGR cooler, while a second valve opens or closes the passage of the gas flow through the EGR cooler bypass.

The single EGR by-pass valve 320a is design in such a way to manage by itself the gas flow through both the EGR cooler 310 and the EGR cooler bypass 310a. As a matter of fact the EGR by-pass valve 320a can selectively close and/or open the exhaust gas flow from exhaust manifold 225 to EGR cooler 310, to EGR cooler bypass 3lCa passage or both. Such by-pass valve 320a is also used for metering the flow entering the EGR cooler or the EGR cooler by-pass.

Figures 4a-4d show a schematic sectional view of the single by-pass valve 320a with relative working positions mounted in a simplified EGR valve assembly according to an exemplary embodiment of the invention.

The single by-pass valve 320a comprises a shut-off member 2 and a housing 1, said housing 1 being provided with an inlet opening Fl, a first outlet opening E2, and a second outlet opening F3.

The inlet opening Fl is connected to the exhaust gas manifold 225 through a passage El, the first opening F2 is connected to the cooler by-pass 310a through a passage P2 and the second outlet opening F3 is directly connected to the EGR cooler 310.

The inlet opening El and the first outlet opening F2 are preferably placed opposite to one another while the second outlet opening F3 is placed orthogonally to the sliding direction of the shut-off member 2 in the housing 1.

S As a matter of fact the shut-off member 2 slides in said housing 1 following a linear path and comprises a head element 4 and a shaft element 3.

Preferably said head element 4 of the shut-off member 2 has a cylindrical shape and the base of the head element 4 and the second outlet opening F3 have the same shape and dimensions so that the head element 4 can slide through.

The shut-off member 2 slides in said housing 1 selectively closing said inlet opening Fl or the first outlet opening F2 or the second outlet opening F3 as shown respectively in Figures 4a-4c. Moreover, the shut-off member 2 can slide in said housing 1 partially closing at least said inlet opening El for metering the flow as shown in Figure 4d.

In Figure 4a the cylindrical shaped head 4 of the shut-off member 2 closes the ingress of the exhaust gases in the housing 1 of the by-pass valve 320a. The shut-off member 2 is preferably provided with an 0-ring around the head 4 so to guarantee perfect sealing.

By moving the shaft member 3 the inlet opening Fl can be open completely and the first outlet opening F2 closed. In this way the flow goes all through the EGR cooler 310 as shown in Figure 4b.

In case of overcooling, or when needed, the shaft 3 can be moved towards the second outlet opening F3 in order to close said second opening F3 and let the first outlet opening F2 be open so to guarantee to the exhaust gases to flow through the EGR cooler bypass 310a as shown in Figure 4c.

The bypass valve 320a can be used also for metering precisely the ingress of the exhaust gases in the EGR cooler 310 as shown in Figure 4d. The shaft 3 of the shut-off member 2 can be millimetricaly adjustable along the shut-off member path so to meter the gas through the inlet opening Fl. As a matter of fact the shut-off member head 4 can partially close the inlet opening Fl according to the desidered gas flow passing through it.

According to an another exemplary embodiment of the invention the EGR by-pass valve 320a can be integrated at the inlet end of the EGR cooler 310.

According to a further exemplary embodiment of the invention, the EGR cooler 310 is integrated in the intake manifold 200.

While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.