Exhaust gas recirculation module with cooled exhaust gas recirculation valve

Abstract

Exhaust gas recirculation module for an internal combustion engine, in particular of a motor vehicle, comprising an exhaust gas recirculation valve (22) with which a volume flow of recirculated exhaust gas can be determined, and a heat exchanger (16) in which the recirculated exhaust gas can be cooled, wherein the exhaust gas recirculation valve (22) has a valve housing (50) and a valve actuator (60), wherein at least one coolant channel (62) is provided for a coolant with which components of the exhaust gas recirculation module can be cooled, characterized in that the exhaust gas recirculation module has a coolant inlet (18) and a coolant outlet (20) and the at least one coolant channel (62) runs through the exhaust gas recirculation valve (22) and the heat exchanger (16), wherein a branch carries away a portion of the coolant flowing through the coolant channel (62) in the valve housing (50).via an inlet (90) from the coolant channel (62) to a valve actuator (60) and from there via an outlet (92) back into the coolant channel (62).

Description

[0001] The invention relates to an exhaust gas recirculation module for an internal combustion engine, in particular of a motor vehicle, comprising an exhaust gas recirculation valve with which a volume flow of exhaust gas to be recirculated can be determined, and a heat exchanger in which the exhaust gas to be recirculated can be cooled, wherein the exhaust gas recirculation valve has a valve housing and a valve drive, wherein at least one coolant channel is provided for a coolant with which components of the exhaust gas recirculation module can be cooled.

[0002] In internal combustion engines, exhaust gas is typically extracted from the exhaust line and mixed with the combustion air. This serves to reduce nitrogen oxides (NOx) and comply with emission limits according to applicable regulations.

[0003] For example, the exhaust gas can be extracted directly at the exhaust manifold and reintroduced into the intake side of the internal combustion engine. Depending on the conditions, the exhaust gas is either cooled before being fed into the combustion air or fed in uncooled.

[0004] To cool the exhaust gas, the exhaust gas recirculation module features an exhaust gas cooler through which the exhaust gas can be routed. If the exhaust gas is to be supplied uncooled, a bypass is opened (for example, by a vacuum unit that opens or closes a bypass flap valve), allowing the exhaust gas to flow through a bypass channel and bypass the heat exchanger. The total amount of exhaust gas recirculated is controlled by a control valve, which, for example, enables the desired volumetric flow rate based on a map.

[0005] Coolant must be supplied to the exhaust gas recirculation module at various points. Firstly, coolant must be passed through the heat exchanger to extract heat from the recirculated exhaust gas. Secondly, the exhaust gas recirculation valve must be cooled because it is located very close to exhaust-carrying and therefore very hot components. If the exhaust gas recirculation valve were not cooled, there would be a risk of damage.

[0006] In the prior art, there has often been a separate circuit for each of the two components, heat exchanger and exhaust gas recirculation valve, through which coolant is supplied and removed. This solution is comparatively complex, as there are a total of eight interfaces between a cooling medium circuit and the respective component. Furthermore, the solutions known from the prior art are quite space-consuming. Other solutions use a common cooling system, which, however, is not suitable for all exhaust gas recirculation valves because heat-sensitive components are not taken into account. In yet other solutions, the exhaust gas recirculation valve is cooled via additional components in the form of heat exchangers arranged on the exhaust gas recirculation valve. However, this results in increased space requirements and costs.

[0007] DE 10 2004 010 117 A1 discloses an exhaust gas recirculation device comprising an exhaust gas recirculation flow rate control valve, an EGR gas cooler, and a cooling water channel through which coolant flows via a cooling water inlet pipe and a cooling water outlet pipe. The cooling water channel runs through the EGR gas cooler and the exhaust gas recirculation flow rate control valve.

[0008] DE 10 2007 049 336 A1 discloses a module comprising, among other things, an exhaust gas control device and an exhaust gas cooler, wherein a coolant flows into the module via the coolant inlet. A first portion of the coolant is supplied to the exhaust gas cooler through a first opening, and a second portion of the coolant is supplied to the exhaust gas control device through a second opening and a coolant line for cooling a valve seat.

[0009] From DE 10 2007 007 393 A1 an exhaust gas control valve is known which is cooled by means of a cooling plate through which a cooling medium flows, which then enters an exhaust gas heat exchanger via an outlet.

[0010] From DE 10 2013 102 549 A1 an exhaust valve device is known with a valve arranged in a valve housing and an actuator for adjusting the valve, wherein the actuator is surrounded by an actuator housing.

[0011] In addition, a coolant channel is provided that runs through the valve housing and has an inlet and outlet.

[0012] The object of the invention is to simplify the supply of coolant to components of the exhaust gas recirculation module.

[0013] To achieve this object, the invention provides for an exhaust gas recirculation module of the type mentioned at the outset, wherein the exhaust gas recirculation module has a coolant inlet and a coolant outlet, and the at least one coolant channel runs through the exhaust gas recirculation valve and the heat exchanger, wherein a branch directs a portion of the coolant flowing through the coolant channel in the valve housing via an inlet from the coolant channel to a valve drive and from there via an outlet back into the coolant channel. The invention is based on the basic idea of ​​using a single coolant channel that runs through the two components, exhaust gas recirculation valve and heat exchanger. Thus, only an upstream coolant inlet and a downstream coolant outlet are necessary. The branch enables cooling of the valve drive without the need for external connections.

[0014] Preferably, the coolant inlet is arranged at the exhaust gas recirculation valve. This ensures that the exhaust gas recirculation valve is supplied with a coolant at a low temperature. Furthermore, the heat input into the coolant in the exhaust gas recirculation valve is so low that the coolant still has sufficient heat transfer capacity for the requirements of the heat exchanger.

[0015] Preferably, the exhaust gas recirculation valve has a valve housing made of a material with good heat conductivity. This ensures that the coolant can optimally cool all components and that the heat to be dissipated is effectively transferred to the coolant.

[0016] The valve housing can be made of an aluminum alloy, in particular. Aluminum alloys are characterized by good castability and high heat transfer capacity.

[0017] The coolant drain is preferably located at the heat exchanger. This allows the coolant, after absorbing heat from the exhaust gas, to be returned to the coolant circuit, where it releases its heat, for example, to the environment.

[0018] According to a preferred embodiment, the heat exchanger comprises a heat exchanger housing made of a material with good heat conductivity. This ensures effective heat dissipation.

[0019] An aluminum alloy can be used as the material for the heat exchanger housing, resulting in a low component weight.

[0020] Preferably, the valve housing and the heat exchanger housing are attached to each other by means of a flange connection. This results in a mechanically simple, easy-to-assemble structure that can also be sealed with minimal effort.

[0021] According to the preferred embodiment of the invention, the coolant channel is formed within the valve housing and within the heat exchanger housing and extends through the flange connection. In this embodiment, no separate measures are required to establish the sealed coolant flow from the exhaust gas recirculation valve to the heat exchanger; rather, this connection is established automatically when the exhaust gas recirculation valve is mounted on the heat exchanger.

[0022] According to one embodiment of the invention, the coolant channel between the coolant inlet and the coolant outlet runs through additional components. For example, a portion of the coolant can be diverted to cool the valve drive of the exhaust gas recirculation valve without the need for external connections.

[0023] The invention is described below with reference to a preferred embodiment, which is illustrated in the accompanying drawings. In these drawings: - Fig. 1 shows a perspective exploded view of a cylinder head with exhaust gas recirculation module; - Fig. 2 the cylinder head of Fig. 1 with exhaust gas recirculation module in a first perspective view; - Fig. 3 in a perspective view an assembly consisting of exhaust gas recirculation valve and heat exchanger, which in the exhaust gas recirculation assembly of the Fig. 1 and Fig. 2 is used; - Fig. 4 which in Fig. 3 shown assembly in a partial section; - Fig. 5 shows an enlarged detail of the assembly of Fig. 4; - Fig. 6 in an exploded view the exhaust gas recirculation valve of the assembly of Fig. 3; and - Fig. 7 in an enlarged, partially sectioned perspective view a detail of the exhaust gas recirculation valve of Fig. 6.

[0024] Based on the Fig. 1 and Fig. 2, the basic structure of an exhaust gas recirculation module as implemented within the scope of the present invention is explained below.

[0025] A cylinder head 10 is shown, which serves, in a conventional manner, to supply intake air to several cylinders of an internal combustion engine and to discharge combustion gases from the cylinders. The intake air is provided via an intake system 12, and the combustion gases are discharged via an exhaust manifold 14.

[0026] Under certain operating conditions, a portion of the exhaust gas can be extracted from the exhaust system of the internal combustion engine and recirculated to the intake side. Two different flow paths are possible for this.

[0027] A first flow path runs through a heat exchanger 16, in which heat can be extracted from the exhaust gas. A coolant inlet 18 and a coolant outlet 20 are provided for this purpose. An exhaust gas recirculation valve 22, also referred to as a valve unit, is provided to control or regulate the volume flow through the heat exchanger 16.

[0028] A second flow path runs through a bypass channel 24, through which exhaust gas can be directed directly from the exhaust side to the intake side, bypassing the heat exchanger 16. A bypass valve 26 is assigned to the bypass channel 24, with which the volume flow through the bypass channel can be controlled or regulated.

[0029] Core feature of the Fig. 1 and Fig. 2 is that a continuous coolant channel is provided from the coolant inlet 18 to the coolant outlet 20, which extends through the exhaust gas recirculation valve 22 and the heat exchanger 16 (see in particular the arrows in Fig. 4).

[0030] The exhaust gas recirculation valve 22 has a valve housing 50, which is connected to the heat exchanger 16 via a mounting flange 52. Within the valve housing 50, a flow channel A for exhaust gas is formed, through which the exhaust gas can flow from an inlet 54 through a controllable flow cross-section between a valve seat 56 and a valve element 58 to the heat exchanger 16. The valve element 58 is actuated here by a schematically illustrated valve drive 60. This can be, for example, an electromagnetic valve drive. Other electric drives are also conceivable.

[0031] The valve housing 50 is double-walled, at least in sections, so that a coolant channel 62 is formed in the valve housing 50. Through this channel, coolant can flow from the coolant inlet 18 to a plug-in connection 64, where it is transferred into the interior of a heat exchanger housing 66 of the heat exchanger 16. The plug-in connection 64 is integrated into the mounting flange 52 of the valve housing 50 and a mounting flange 68 of the heat exchanger housing 66.

[0032] Within the heat exchanger housing 66, the coolant flows around several heat transfer elements 70, which provide a media-tight separation between the exhaust gas flow and the coolant. The coolant then flows out of the interior of the heat exchanger housing 66 through the coolant outlet 20.

[0033] The valve housing 50 and the heat exchanger housing 66 may both be made of an aluminum alloy so that they are kept at a low temperature by the coolant. A portion of the coolant flowing through the coolant passage 62 in the valve housing 50 may be diverted to cool the valve actuator 60 (see the Fig. 6 and Fig. 7). For this purpose, an inlet 90 is provided, which leads to the valve drive 60, and an outlet 92, which leads the coolant back to the valve housing 50. The inlet 90 is located near the coolant inlet 18. The height of a rib 94 arranged within the valve housing can generate a certain back pressure there, ensuring that the coolant flows through the inlet 90, the valve drive 60, and the outlet 92 back to the coolant channel 62.

[0034] The inlet 90 and the outlet 92 can be designed as small nozzles located in the parting plane between the valve housing 50 and the valve actuator 60. This automatically creates a media-tight connection of the valve actuator 60 to the coolant channel 62 when the valve actuator 60 is mounted on the valve housing 50.

Claims

[1] Exhaust gas recirculation module for an internal combustion engine, in particular of a motor vehicle, with an exhaust gas recirculation valve (22) with which a volume flow of exhaust gas to be recirculated can be determined, and a heat exchanger (16) in which the exhaust gas to be recirculated can be cooled, wherein the exhaust gas recirculation valve (22) has a valve housing (50) and a valve drive (60), wherein at least one coolant channel (62) is provided for a coolant with which components of the exhaust gas recirculation module can be cooled, characterized byin that the exhaust gas recirculation module has a coolant inlet (18) and a coolant outlet (20) and the at least one coolant channel (62) runs through the exhaust gas recirculation valve (22) and the heat exchanger (16), wherein a branch directs a portion of the coolant flowing through the coolant channel (62) in the valve housing (50) via an inlet (90) from the coolant channel (62) to a valve drive (60) and from there via an outlet (92) back into the coolant channel (62). [2] Exhaust gas recirculation module according to claim 1, characterized by that the coolant inlet (18) is arranged on the exhaust gas recirculation valve (22). [3] Exhaust gas recirculation module according to claim 1 or claim 2, characterized by that the valve housing (50) is made of a material with good heat conduction. [4] Exhaust gas recirculation module according to claim 3, characterized by that the valve housing (50) is made of an aluminum alloy. [5] Exhaust gas recirculation module according to one of the preceding claims, characterized by that the coolant drain (20) is arranged on the heat exchanger (16). [6] Exhaust gas recirculation module according to one of the preceding claims, characterized by that the heat exchanger (16) has a heat exchanger housing (66) which consists of a material with good heat conduction. [7] Exhaust gas recirculation module according to claim 6, characterized by that the heat exchanger housing (66) is made of an aluminum alloy. [8] Exhaust gas recirculation module according to one of claims 6 and 7 in combination with one of claims 3 and 4, characterized by that the valve housing (50) and the heat exchanger housing (66) are fastened to one another by means of a flange connection (52, 68). [9] Exhaust gas recirculation module according to claim 8, characterized bythat the coolant channel (62) is formed within the valve housing (50) and within the heat exchanger housing (66) and extends through the flange connection. [10] Exhaust gas recirculation module according to one of the preceding claims, characterized by that the coolant channel (62) runs between the coolant inlet (18) and the coolant outlet (20) through further components (60).

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