Valve for regulating an exhaust gas flow of an internal combustion engine, heat exchanger for exhaust gas cooling, system having at least one valve and having at least one heat exchanger

The present invention relates to a valve for regulating an exhaust gas flow of an internal combustion engine according to the preamble of claim 1 and to a heat exchanger for cooling exhaust gas having at least one valve, and a system having at least one valve and having at least one heat exchanger.

In order to meet the current and future exhaust gas emission regulations, cooled exhaust gas recirculation is being used in diesel engines and/or spark ignition engines for passenger cars or for utility vehicles as a means of reducing the nitrogen oxide emissions (NOx). Reliability problems of these systems are caused, for example, by failures or faults in a EGR valve which are due to the thermal loading by the hot exhaust gas stream or the formation of deposits from the exhaust gas stream. An EGR valve controls, in particular, the mass flow of recirculated exhaust gas which can flow through a heat exchanger, in particular an exhaust gas heat exchanger. The EGR valve can usually be actuated or activated electrically or pneumatically. The EGR valve can have various open-loop or closed-loop control positions. In a first position, the EGR valve prevents, for example, exhaust gas from flowing through the exhaust gas heat exchanger. In a second position, for example the entire mass flow of recirculated exhaust gas flows through the exhaust gas heat exchanger. In a third position of the EGR valve, a mass flow of recirculated gas flows through the exhaust gas heat exchanger, said mass flow being between zero mass flow of recirculated gas and the maximum mass flow of recirculated gas.

The EGR valve can be arranged downstream or upstream of the heat exchanger, in particular of the exhaust gas cooler. In addition, the EGR valve can be arranged in, or adjacent to, the exhaust gas cooler. In a further embodiment, the EGR valve can be embodied in one piece with the heat exchanger, in particular the exhaust gas cooler.

The EGR valve and the heat exchanger, in particular the exhaust gas cooler, can be arranged in a system having at least one internal combustion engine and at least one turbine, with which, in particular, a compressor for supercharging charge air or charge air and exhaust gas can be driven, on the outflow side of the turbine, i.e. on the low pressure side, or on the inflow side of the turbine, i.e. on the high pressure side.

When the EGR valve is arranged on the inflow side of the heat exchanger, in particular of the exhaust gas cooler, the EGR valve is subjected to high temperature requirements owing to the hot exhaust gas. It is known in this context that the temperature requirement of the EGR valve can be reduced if the exhaust gas is not fed directly to the EGR valve from the exhaust section but instead the recirculated exhaust gas is not fed to the EGR valve and/or the exhaust gas heat exchanger until it has passed through the cylinder head of the engine. As a result of this routing of exhaust gas, heat is already extracted from the hot exhaust gas by the engine coolant before said hot exhaust gas is in contact with the EGR valve. Nevertheless, the EGR valve still experiences very high temperature loading.

The arrangement of the EGR valve downstream of the exhaust gas cooler is usually selected in order to reduce the temperature loading of the EGR valve and of the corresponding actuator, in particular of the electrical or pneumatic actuator. However, it is disadvantageous here that the unburnt hydrocarbons (HC) which are contained in the exhaust gas form deposits on the EGR valve in conjunction with soot particles. As a result of the relatively low gas temperatures after the exhaust gas has flowed through the exhaust gas heat exchanger, the deposits which are formed in the EGR valve can be removed again only with difficulty since, for example, the deposits can only be burnt off with difficulty. The deposits cause the valve to become blocked due to sooting up or carbonizing and is therefore no longer functionally capable.

On the other hand, arranging the EGR valve on the inflow side of the exhaust gas cooler makes it possible, owing to the high exhaust gas temperatures upstream of the exhaust gas heat exchanger, to burn off the deposits which are formed, for example in relatively high-load operating states of the internal combustion engine. However, the high temperature loading of the EGR valve also leads to heavy loading of the actuator. Even after the recirculated exhaust gas cools in the cylinder head, the actuator and EGR valve are still heavily loaded by the engine coolant.

The applicant\'s unpublished document DE 102 005 029 322.0 discloses an EGR valve and an arrangement for recirculating and cooling exhaust gas of an internal combustion engine with an EGR valve. In one exemplary embodiment, the valve device is arranged here on the inflow side of a high temperature cooler, or in another exemplary embodiment the exhaust gas cooler is arranged on the outflow side.

In addition, in the applicant\'s document DE 102 005 048 911.7, which is also still unpublished, an arrangement is disclosed for recirculating and cooling exhaust gas of an internal combustion engine in which an EGR valve is arranged on the outflow side of an exhaust gas cooler. In the applicant\'s document DE 102 005 049 309.2, which is also still unpublished, an EGR valve is disclosed, which has, in particular, an oxidation catalytic converter on the inflow side of an exhaust gas cooler.

In the applicant\'s unpublished document DE 102 005 044 088.6, it is disclosed that an EGR valve is integrated into the inlet diffuser of a heat exchanger, in particular of an exhaust gas heat exchanger.

The object of the present invention is to improve a valve of the type mentioned at the beginning.

The object is achieved by means of the features of claim 1.

Further advantageous refinements of the invention emerge from the subclaims and from the drawings.

A valve is proposed for regulating an exhaust gas flow of an internal combustion engine which has at least one closure element and at least one actuator for activating the closure element, wherein the valve has at least one heat transfer duct for cooling the valve, through which heat transfer duct at least one first medium can flow.

The at last one closure element can perform open-loop or closed-loop control on, in particular, a mass flow of a second medium such as, for example, exhaust gas. The closure element can be actuated by means of an actuator. The valve has at least one heat transfer duct for cooling the valve, through which heat transfer duct at least one medium, in particular coolant such as cooling fluid or air can flow or does flow.

In one advantageous development, the heat transfer duct is embodied as an annular duct. The first medium, in particular cooling fluid or air, can particularly advantageously flow from an inlet opening to an outlet opening here.

In addition it is possible to provide that the heat transfer duct has at least one wall pairing whose walls are embodied concentrically with respect to one another. In this way, the flow duct can particularly advantageously be formed in a plate by means of primary shaping fabrication methods such as, for example, injection molding, or by means of a material-removing fabrication method such as, for example, milling.

In one advantageous development, the valve has at least a first opening for the inflow of the first medium and/or at least a second opening for the outflow of the first medium. In this way, the first medium can particularly advantageously flow through the heat transfer duct via the first opening, and the first medium can particularly advantageously flow out again from the second opening after it has flowed through the heat transfer duct.

In addition it is possible to provide that the first medium is coolant, in particular a cooling fluid or air. In this way, the valve can be cooled particularly advantageously.

Furthermore, it can particularly preferably be provided that the valve has at least one plate in which the heat transfer duct is arranged. In this way, the heat transfer duct can particularly advantageously be provided in the plate, for example by means of a primary shaping fabrication method such as injection molding, or by means of a material-removing fabrication method such as milling or drilling, and can particularly advantageously be connected to the valve.

In a further advantageous embodiment, the plate has reinforcing devices and/or cavities in order to save weight. In this way, the plate can be made particularly lightweight.

In addition it is possible to provide that the plate is connected to a valve housing in a materially joined and/or positively locking fashion. In this way, the plate can particularly advantageously be connected to the valve housing, for example by soldering, welding, bonding etc. and/or particularly advantageously connected in a positively locking fashion.

In a further advantageous development, the plate is embodied in one piece with the valve housing. In this way, it is possible, in particularly advantageous way, to make savings in terms of assembly processes.