EP2630353B1

EP2630353B1 - Turbocharger egr module

Info

Publication number: EP2630353B1
Application number: EP11834877.0A
Authority: EP
Inventors: Robert D. Keefover
Original assignee: BorgWarner Inc
Current assignee: BorgWarner Inc
Priority date: 2010-10-18
Filing date: 2011-10-13
Publication date: 2015-11-25
Anticipated expiration: 2031-10-13
Also published as: WO2012054282A3; EP2630353A4; US20130195628A1; CN103154468A; WO2012054282A2; EP2630353A2; KR20130143052A

Description

This application claims the benefit of United States Provisional Application Serial Number 61/394,023 filed October 18, 2011 .

TECHICAL FIELD

The technical field generally relates to products including turbochargers for internal combustion engines having an exhaust gas recirculation valve. In particular, the invention concerns a product according to the preamble part of claim 1. Such a product is known from WO 2006/122306 A2 . US 2008/223038 A1 is an example for the integration of a low pressure loop EGR valve in a compressor housing. US 2010/024414 A1 discloses the integration of a high pressure loop EGR valve in a turbine housing.

BACKGROUND

Federal and State legislation require control of vehicle exhaust emissions. Oxides of Nitrogen (NOx) are one of the exhaust gas emissions that must be controlled. Formation of NOx will occur at higher combustion temperatures. A system, referred to as the exhaust gas recirculation system, has been developed to reduce excess oxygen and combustion temperatures to control NOx emissions. A portion of the exhaust gas is recirculated back to the intake where it will be combined with incoming air reducing excess oxygen content in the total air mixture. When this mixture is compressed and ignited in the cylinder, the result is a reduction in NOx due to reduced oxygen content and a lower combustion temperature. A schematic of this system is shown in Figure 1.
The traditional system consists of the "high pressure" EGR loop, named because the EGR loop operates on the high pressure side between the engine and the turbocharger 7. This EGR loop consists of an exhaust gas recirculation (EGR) valve 1 that controls the flow of exhaust gas to the intake manifold 2. The EGR valve shown in Figure 1 is positioned after (cold side) the exhaust gas cooler 5, but it may also be positioned before (hot side) the cooler. As the EGR valve opens and closes it will increase or decrease the flow rate of exhaust gas to the intake manifold. It is also typical to have a throttle valve 6 to control airflow and pressure in the intake manifold and, an exhaust gas cooler 5 to reduce temperature of recirculated exhaust gas, and a cooler bypass valve 4 to bypass exhaust gas around the cooler under certain operating conditions.
To further reduce NOx and improve vehicle fuel economy, recently developed engine systems may add an additional "low pressure" EGR loop that operates on the low pressure side of the turbocharger, after the exhaust turbine and before intake compressor. This system consists of another EGR valve 10 to control the flow rate of exhaust gas to the air intake, and an exhaust throttle valve 11 to control the exhaust back pressure needed to drive the exhaust gas flow. This EGR loop may also includes a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) 9, and an additional exhaust gas cooler 12. Low pressure loop exhaust gas has the additional advantage of passing through the air charge cooler 8 before reaching the engine. Similar to the high pressure loop, the low pressure loop valve can be placed either before (hot side) or after (cold side) the exhaust gas cooler.
EGR valves may be actuated by hydraulic, pneumatic, or electric means. Pneumatically actuated valves depend upon the availability of pressure or vacuum on the vehicle and this may be an undesirable requirement. They also require a means of electrically controlling the pneumatic source to allow overall electrical control of the system. An electric vacuum or pressure regulator is used to provide this control. Operating force is another factor used in the selection criteria for the type of actuator used for the EGR valve. Higher flow rates require larger valves with greater area and higher operating forces. Lower pressure differential between the exhaust and intake manifold will require larger valves to achieve the desired flow rate. Contamination in the exhaust gas can accumulate on the valve components and cause them to stick or restrict movement if sufficient operating force is not available.
The type of valve technology best suited to a particular application is at least partially driven by the required EGR flow rate. Single poppet valves are well suited for typical engine applications because of low gas leakage passed the valve when the valve is closed. Because the operating forces required typically increase with the valve size, for higher EGR flow rates in moderately sized engines dual poppet valves (two poppet valves on the same shaft) are often chosen; a dual poppet valve increases the flow capacity of a poppet valve while balancing and reducing the required operating forces. For very high EGR flow rates in large engine applications, where a poppet valve or dual poppet valve would need to be very large (> 32 mm in diameter), a throttle valve (or butterfly valve) potentially becomes an attractive solution. A throttle valve is also a potentially attractive solution for "low pressure loop" EGR systems due to lower differential valve pressure and subsequent less stringent requirements for gas leakage when the valve is closed. When compared to a poppet valve: 1) a throttle valve is not typically able to achieve the low leakage rates of a poppet valve, this however is typically of less importance for very large engines. 2) a throttle valve is naturally balanced resulting in lower operating forces for very large valves. 3) a throttle valve can typically achieve a similar EGR flow rate in a smaller diameter valve because of their inherently higher flow efficiency.
EGR valves, and other valves that control the flow of high temperature fluids, may have components that are sensitive to the high temperature. These components may include: actuators, shaft seals, bearings, position sensors, and plastic molded parts. Typical actuators may include: pneumatic devices, linear solenoids, torque motors, stepper motors, and D.C. motors. Additional measures such as liquid cooling, heat shields, remote mounting, or use of expensive materials may be required to achieve suitable durability when operating at the high temperature.

SUMMARY OF SELECT EMBODIMENTS

The invention includes a product including a turbocharger including a turbine torsionally connected to a compressor and a compressor housing fixed to a turbine housing. An exhaust gas recirculation valve is mounted on at least one of the compressor housing and the turbine housing.
Other exemplary embodiments of the invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while disclosing exemplary embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a generalized schematic illustration of a prior art EGR system utilizing a turbocharger.
FIG. 2 is a generalized schematic illustration EGR system utilizing a turbocharger according to one embodiment.
FIG. 3 is a perspective exploded view of a turbocharger and EGR valves according to one embodiment.
FIG. 4 is a generalized schematic illustration of another prior art EGR system utilizing a turbocharger.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The invention includes integration of several of the EGR valves with the turbocharger. The placement of the EGR valves within the engine system architecture is chosen such that that the exhaust gas inlet for the high pressure EGR valve 1 coincides with a junction to the inlet to the turbine of the turbo charger 7 and such that the outlet of the low pressure EGR valve 10 coincides with a junction to the inlet to the compressor of the turbo charger 7. Configuring the system in this manner allows for the potential to integrate one or more of the EGR valves into the packaging of the turbocharger assembly. A schematic of a system with a Turbo EGR module according to the invention is shown in Figure 2.
The module concept can be extended further with the possibility to integrate the EGR cooler bypass valve 4, and/or a low pressure intake valve 13, and/or a gas mixer/diffuser 14 at the junction between the low pressure exhaust gas and the inlet to the compressor from a prior art system as illustrated in Figure 4.
Another embodiment is shown pictorially in Figure 3, in which a throttle type low pressure loop EGR valve is integrated to the inlet of the turbo compressor and/or a poppet type high pressure EGR valve is integrated to the inlet of the turbo turbine.
numerous embodiments are within the scope of the invention include but not limited to the following.
Embodiment 1 includes a product comprising: a turbocharger comprising a turbine torsionally connected to a compressor, a housing for said turbine, a housing for said compressor fixed with respect to said turbine housing;
wherein there is a low pressure exhaust gas recirculation valve mounted on said compressor housing.
wherein there is a high pressure exhaust gas recirculation valve mounted on said turbine housing.
Embodiment 2 may include a product wherein said exhaust gas recirculation valve is a poppet type valve.
Embodiment 3 may include a product wherein said exhaust gas recirculation valve is water cooled,
Embodiment 4 may include a product wherein said exhaust gas recirculation valve has a DC motor drive.
Embodiment 5 may include a product further comprising a cooler bypass valve mounted to said turbine housing.
Embodiment 6 may include a product wherein said exhaust gas recirculation valve has a DC motor drive.
Embodiment 7 may include a product wherein said exhaust gas recirculation valve is a throttle type valve.
Embodiment 8 may include a product further comprising an exhaust gas mixing unit mounted between said compressor housing and said exhaust gas recirculation valve.
Embodiment 12 may include a product further comprising an intake valve mounted to said compressor housing.
The description of the invention is merely exemplary (illustrative) in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention.

Claims

A product comprising:
a turbocharger (7) comprising a turbine torsionally connected to a compressor,

a housing for said turbine, and

a housing for said compressor fixed with respect to said turbine housing; characterized in that

a high pressure exhaust gas recirculation valve (1) is mounted on said turbine which coincides with an inlet to said turbine and wherein there is a low pressure exhaust gas recirculation valve (10) mounted on said compressor housing which coincides with an inlet to said compressor.
A product as described in claim 1 wherein said high pressure exhaust gas recirculation valve (1) is a poppet type valve.
A product as described in claim 1 wherein said high pressure exhaust gas recirculation valve (1) is water cooled.
A product as described in claim 1 wherein said high pressure exhaust gas recirculation valve (1) has a DC motor drive.
A product as described in claim 1 further comprising a cooler bypass valve (4) mounted to said turbine housing.
A product as described in claim 1 wherein said low pressure exhaust gas recirculation valve (10) has a DC motor drive.
A product as described in claim 1 wherein said low pressure exhaust gas recirculation valve (10) is a throttle type valve.
A product as described in claim 1 further comprising an exhaust gas mixing unit (14) mounted between said compressor housing and said low pressure exhaust gas recirculation valve.
A product as described in claim 1 further comprising an intake valve (13) mounted to said compressor housing.