AT523180B1 - COMBUSTION MACHINE WITH MULTIPLE CYLINDERS - Google Patents

Abstract

The invention relates to an internal combustion engine (1) with several cylinders (21, 22, 23, 24) with an intake system (3) and an exhaust system (4), as well as an exhaust gas recirculation system (5) for recirculating exhaust gas from the exhaust system (4) in the intake system (3), wherein the exhaust gas recirculation system (5) has at least one exhaust gas recirculation flow path (50) in which at least one exhaust gas cooling device (8) with at least one exhaust gas cooler (80; 81, 82, 83, 84) is arranged. In order to achieve an even distribution of the condensate to the individual cylinders, it is provided that the exhaust gas recirculation flow path (50) in or upstream of the exhaust gas cooling device (8) is divided into partial exhaust gas flows and the partial exhaust gas flows for cylinder-selective exhaust gas recirculation in cylinder-selective exhaust gas recirculation paths (51, 52, 53 , 54), with each cylinder (21, 22, 23, 24) being assigned at least one cylinder-selective exhaust gas recirculation path (51, 52, 53, 54) which enters an inlet flow path (31, 32, 33, 34) of the assigned cylinder (21, 22, 23, 24) or opens directly into the associated cylinder (21, 22, 23, 24).

Description

description

The invention relates to an internal combustion engine with several cylinders, an intake system, an exhaust system and an exhaust gas recirculation system for recirculating exhaust gas from the exhaust system into the intake system, the exhaust gas recirculation system having at least one exhaust gas recirculation flow path in which at least one exhaust gas cooling device is arranged with at least one exhaust gas cooler , wherein the exhaust gas recirculation flow path in or upstream of the exhaust gas cooling device is divided into partial exhaust gas flows and the partial exhaust gas flows for cylinder-selective exhaust gas recirculation are guided in cylinder-selective exhaust gas recirculation paths, each cylinder being assigned at least one cylinder-selective exhaust gas recirculation path which opens into an inlet flow path of the assigned cylinder or directly into the assigned cylinder .

Internal combustion engines with different exhaust gas recirculation devices and systems are known in the prior art. It has been shown that the fuel efficiency of a vehicle can be increased by using exhaust gas recirculation. In order to reduce emissions, various systems have been introduced in recent years, through which the exhaust gas is returned to each cylinder to improve combustion.

US 2018/0179999 A1 describes an intake manifold for an internal combustion engine with an exhaust gas recirculation flow path and an exhaust gas cooling device. Downstream of the exhaust gas cooling device, the recirculated exhaust gas is divided into individual exhaust gas streams in a cylinder-selective manner, each exhaust gas stream opening into an inlet pipe.

US 2019/0170095 A1 shows an EGR manifold which is connected to the inlet manifold in order to supply EGR gas to the inlet pipes in a cylinder-selective manner. The EGR distributor is arranged adjacent to a heating part through which hot water flows.

DE 601 26 190 T2 describes a device for feeding blow-by gases and recirculated exhaust gases into an inlet line, the exhaust gas being fed via a corrugated pipe to an exhaust gas recirculation chamber unit, the cover of which has parallel cooling fins on the upper surface.

DE 689 01 853 T2 describes an adapter for intake manifolds, which has a connecting pipe having cooling fins for returning the exhaust gas of an internal combustion engine.

JP H08210196 A discloses a direct injection diesel internal combustion engine with a plurality of cylinders, exhaust gas being taken from one cylinder and supplied to an adjacent cylinder via a solenoid valve.

WO 2014/140150 A1 describes an internal combustion engine with a plurality of cylinders with an exhaust gas recirculation path between the exhaust system and the intake system, which has an exhaust gas cooler. Downstream of an electric compressor and downstream of an exhaust gas cooler, the exhaust gas recirculation path is divided into individual cylinder-selective supply channels, with at least one supply channel opening into an inlet flow path for each cylinder. Another cylinder-selective exhaust gas recirculation device is known from DE 10 2007 033 675 A1.

When recirculated exhaust gas is cooled, condensate is formed, which is usually separated off and stored in a buffer. From DE 10 2015 200 706 A1 it is known to feed this stored condensate to the fresh gas tract or to inject the condensate into the combustion chamber of the internal combustion engine. The aim is, on the one hand, to reduce the tendency to knock and, on the other hand, to reduce high exhaust gas temperatures. Similar arrangements are also described in the publications DE 10 2016 205 666 A1, DE 10 2016 207 189 A1, EP 2 998 560 A1, US 9,145,850 B2 or WO 2009/045154 A1.

The known solutions have the disadvantage that without controlled further processing of the condensate - e.g. by pumps or volume dividing devices - the uniform supply of the condensate to the individual cylinders is not ensured. So it can be

come that individual cylinders are oversupplied with condensate, while others are undersupplied. The provision of pumps and other processing devices increases costs and leads to disadvantages in packaging.

It is therefore the object of the invention to ensure an even distribution of the condensate to the individual cylinders in the simplest possible manner in an internal combustion engine with an exhaust gas recirculation system.

Starting from an internal combustion engine of the type mentioned, this object is achieved according to the invention in that the exhaust gas cooling device has an exhaust gas cooler with a manifold, the exhaust gas cooler between the manifold and an exhaust gas outlet area from the exhaust gas cooler having several flow channels, the individual flow channels in terms of flow are separated, and that a group of at least two flow channels is each assigned to a cylinder-selective exhaust gas recirculation path and the assigned cylinder-selective exhaust gas recirculation path in the exhaust gas outlet area of the exhaust gas cooler emanates from a collecting chamber assigned to the cylinder-selective exhaust gas recirculation path, into which the flow channels of a group open.

One embodiment of the invention provides that the exhaust gas cooling device has several exhaust gas coolers, each exhaust gas recirculation path being assigned at least one exhaust gas cooler, and wherein the exhaust gas recirculation flow path is divided into the parallel flow through cylinder-selective exhaust gas recirculation paths upstream of the exhaust gas cooler. In other words, at least one exhaust gas cooler is operatively connected to each exhaust gas recirculation path. The exhaust gas routed in the exhaust gas recirculation path is thus cooled by the exhaust gas cooler.

In another embodiment of the invention it is provided that the distributor space is arranged in the region of an exhaust gas inlet into the exhaust gas cooler. In each case one flow channel is preferably assigned to a cylinder-selective exhaust gas recirculation path, the assigned cylinder-selective exhaust gas recirculation path starting in the exhaust gas outlet region of the exhaust gas cooler from this assigned flow channel.

The fact that a group of at least two flow channels is each assigned to a cylinder-selective exhaust gas recirculation path and the assigned cylinder-selective exhaust gas recirculation path in the exhaust gas outlet area of the exhaust gas cooler emanates from a collecting chamber assigned to the cylinder-selective exhaust gas recirculation path, into which the flow channels of a group open, particularly good cooling can be achieved because the division into several flow channels results in more surface that can be brought into operative contact with the exhaust gas cooler.

The cylinder-selective exhaust gas paths are not only - as in the prior art - after the exhaust gas cooling device, but already before or in the exhaust gas cooling device performed separately from one another. The exhaust gas recirculation flow path is advantageously divided up in a condensation-free area of the exhaust gas cooling device. In other words, the exhaust gas recirculation flow path is divided up in the exhaust gas cooling device upstream of a region in which a condensate-forming cooling effect occurs. The condensate formation takes place after the division in each case in the individual flow channels and / or exhaust gas recirculation paths. The division of the exhaust gas recirculation flow path upstream of the exhaust gas cooling device or in the condensation-free area of the exhaust gas cooling device ensures that the condensate is evenly distributed over the individual cylinders.

Thus, the condensate is not collected in a container as in the solutions known from the prior art and only then fed to the individual cylinders. Rather, the condensate arising in the individual flow channels and / or flow paths within the exhaust gas cooling device is fed together with the cooled exhaust gas either directly to each individual cylinder or at least to one inlet flow path of each cylinder. Components such as condensate collecting tanks, condensate lines, condensate pumps and condensate injection devices are therefore not absolutely necessary and can be omitted. On the one hand, this frees up installation space and reduces the number of components required. On the other hand

only a few parts are exposed to the corrosive condensate, thus significantly reducing maintenance costs.

In order to achieve an equal distribution of the condensate to the individual cylinders, it is advantageous if the length differences between at least two adjacent cylinder-selective exhaust gas recirculation paths between the division of the exhaust gas flow path and the opening in the inlet flow path or in the cylinder is a maximum of 10%, preferably a maximum 5%, particularly preferably a maximum of 2% of the length of the longest exhaust gas recirculation path.

A particularly good uniform distribution of the condensate is possible if at least two - preferably all - cylinder-selective exhaust gas recirculation paths have approximately the same length and / or the same cross section. The cylinder-selective exhaust gas recirculation paths are expediently made as short as possible.

As a result, the same amount of recirculated exhaust gas is supplied to each inlet flow path and / or each cylinder on the one hand, and the same amount of condensate on the other hand.

In a further development of the invention it can be provided that at least one cylinder-selective exhaust gas recirculation path - at least in sections - is designed to be thermally insulated.

In order not to negatively affect the exhaust gas recirculation paths on the degree of delivery, one embodiment of the invention provides that the oscillation lengths of the cylinder-selective exhaust gas recirculation paths are matched to the oscillation lengths of the inlet flow paths or intake pipes (e.g. 31-51) of the internal combustion engine. In other words, the oscillation length of an exhaust gas recirculation path assigned to a cylinder is matched to the oscillation length of the inlet flow path assigned to this cylinder.

For the even distribution of the condensate to the individual cylinders, it is advantageous if the exhaust gas cooling device is arranged near the openings in the inlet channels or near the openings in the cylinder. This also minimizes the variation in the corresponding amounts of heat and the result is an even maintenance of the liquid phase of the condensate. According to a variant embodiment of the invention, the exhaust gas cooling device is arranged between an inlet manifold of the inlet system and the cylinders.

The invention is explained in more detail below with reference to the non-limiting exemplary embodiments shown in the figures. They show schematically:

1 shows an internal combustion engine according to the invention in a first variant,

2 shows an internal combustion engine according to the invention in a second embodiment variant,

3a shows a first variant of an exhaust gas cooling device, [0028] FIG. 3b shows a second variant of an exhaust gas cooling device, and [0029] FIG. 3c shows a third variant of an exhaust gas cooling device.

The same elements are provided with the same reference symbols in the design variants.

1 and 2 show an internal combustion engine 1 with several cylinders 21, 22, 23, 24 with an intake system 3 and an exhaust system 4, and an exhaust gas recirculation system 5 for recirculating exhaust gas from the exhaust system 4 into the intake system 3. The exhaust system 4 has an exhaust gas aftertreatment system 6, the components of which, formed for example by three-way catalytic converters and / or particle filters, are designated by 61, 62. In principle, the components of the exhaust gas aftertreatment system 6 can be selected as desired or according to the respective requirements.

The intake system 3 has an intake manifold 30, from which intake flow paths 31, 32, 33, which lead to the individual cylinders 21, 22, 23, 24 of the internal combustion engine 1,

34 go out.

The exhaust gas recirculation system 5 has an exhaust gas recirculation flow path 50 in which at least one exhaust gas recirculation valve 7 and an exhaust gas cooling device 8 with at least one exhaust gas cooler 80 is arranged, the exhaust gas recirculation valve 7, for example, upstream of the exhaust gas cooler 80 (Fig. 1, 2) or the exhaust gas cooler 81, 82, 83, 84 (Fig. 3a) is arranged. Optionally, a single-flow exhaust gas precooler 9 can also be arranged upstream of the exhaust gas recirculation valve 7 in addition to the exhaust gas cooling device 8, as shown in FIG. 1 by dotted lines. Single flow means that the exhaust gas flow path 50 is not divided into partial exhaust gas flows.

The dashed lines 50a, 50b, 50c, 50d in Figs. 1 and 2 show different possible variants of the removal of the recirculated exhaust gas from the exhaust system 4 or the exhaust gas aftertreatment system 6. The recirculated exhaust gas can be the exhaust system 4 via the exhaust gas recirculation line 50a on the exhaust tract 41 of a cylinder 21, 22, 23, 24 or via the exhaust gas recirculation line 50b after the merging of the exhaust tracts 41, 42, 43, 44 of several cylinders 21, 22, 23, 24 upstream of the exhaust gas aftertreatment system 6 or via the exhaust gas recirculation line 50c between two components 61, 62 of the exhaust gas aftertreatment system 6 or via the exhaust gas recirculation line 50d after the exhaust gas aftertreatment system 6.

In all embodiment variants, the exhaust gas recirculation flow path 50 is divided according to the invention in or downstream of the exhaust gas cooling device 8 into cylinder-selective exhaust gas recirculation paths 51, 52, 53, 54 through which partial exhaust gas flows flow in parallel, with each cylinder 21, 22, 23, 24 having at least one cylinder-selective one for the cylinder-selective exhaust gas recirculation Exhaust gas recirculation path 51, 52, 53, 54 is assigned, which opens into an inlet flow path 31, 32, 33, 34 of the assigned cylinder 21, 22, 23, 24 or directly into the assigned cylinder 21, 22, 23, 24.

There is thus a flood separation of the exhaust gas flow before or within the exhaust gas cooling device 8. Flood separation means in the context of the present disclosure that an exhaust gas flow is divided into several exhaust gas partial flows, the exhaust gas partial flows being passed into the separate cylinder-selective exhaust gas recirculation paths 51, 52, 53, 54 become.

The length differences between the cylinder-selective exhaust gas recirculation paths 51, 52, 53, 54 between the division of the exhaust gas flow path 50 and the opening in the inlet flow path 31, 32, 33, 34 or in the cylinder 21, 22, 23, 24 are a maximum of 10 %, preferably a maximum of 5%, particularly preferably a maximum of 2% of the length of the longest exhaust gas recirculation path 51, 52, 53, 54. It is particularly advantageous for the even distribution of the recirculated exhaust gas and the condensate if the cylinder-selective exhaust gas recirculation paths 51, 52, 53, 54 all have approximately the same length and the same cross section, the exhaust gas recirculation paths 51, 52, 53, 54 should be dimensioned as short as possible. This can be achieved, for example, if the exhaust gas cooling device 8 is arranged between the inlet manifold 30 and the cylinders 21, 22, 23, 24 of the internal combustion engine 1, as shown in FIG. 1. In Fig. 1, an internal combustion engine 1 is shown only schematically - in a real implementation, the exhaust gas cooling device 8 would be arranged above and / or below the pipes running between the inlet manifold 30 and cylinders 21, 22, 23, 24.

In particular, it is advantageous if the line run downstream of the exhaust gas cooler 80 in the direction of the inlet flow paths 31, 32, 33, 34 of the associated cylinders 21, 22, 23, 24 or - depending on the embodiment - directly into the cylinder 21, 22, 23, 24, when the internal combustion engine 1 is used as intended, is designed to decrease in the geodetic sense. It can thus be ensured that the condensate is fed to the combustion and does not remain in the lines of the exhaust gas recirculation system 5 or possibly even the outlet system 4.

In addition, the lengths of the cylinder-selective exhaust gas recirculation paths 51, 52, 53, 54 can each be matched to an oscillation length of the associated inlet flow paths 31, 32, 33, 34 of the internal combustion engine 1 in order to enable a high degree of filling.

To downstream of the exhaust gas cooling device 8, an uneven formation of condensate

To avoid different heat transports, the cylinder-selective exhaust gas recirculation paths 51, 52, 53, 54 can be designed to be thermally insulated.

The exhaust gas cooling device 8 can have a plurality of individual exhaust gas coolers 81, 82, 83, 84 through which there is parallel flow, as is shown in FIG. 3a. An exhaust gas cooler 81, 82, 83, 84 is assigned to each cylinder 21, 22, 23, 24. In this case, the flow separation into individual exhaust gas recirculation paths 51, 52, 53, 54 takes place before entering the exhaust gas cooling device 8. An exhaust gas cooler 81, 82, 83, 84 is arranged in each exhaust gas recirculation path 51, 52, 53, 54. The exhaust gas recirculation flow path 50 is divided into the cylinder-selective exhaust gas recirculation paths 51, 52, 53, 54 through which there is parallel flow, that is, upstream of the cylinder-selective exhaust gas cooler 81, 82, 83, 84.

In the embodiment variants shown in FIGS. 3b and 3c, the exhaust gas cooling device 8 has a common or one-piece exhaust gas cooler 80.

In FIG. 3b, another embodiment variant is shown, in which the exhaust gas cooling device 8 has an exhaust gas cooler 80 with a distributor space 802 arranged in the region of an exhaust gas inlet 801 in the exhaust gas cooler 80. The exhaust gas cooler 80 has a plurality of flow channels 101, 102, 103, 104 between the distributor space 802 and an exhaust gas outlet region 803 from the exhaust gas cooler 80, the individual flow channels 101, 102, 103, 104 being separated in terms of flow. A flow channel 101; 102; 103; 104 exactly one cylinder-selective exhaust gas recirculation path 51; 52; 53; 54 assigned. This cylinder-selective exhaust gas recirculation path 51; 52; 53; 54 starts in the exhaust gas outlet region 803 of the exhaust gas cooler 80 from the flow channel. The multi-flow exhaust gas cooler thus has one flow per exhaust gas recirculation path 51, 52, 53, 54 and thus per cylinder 21, 22, 23, 24. The exhaust gas recirculation paths 51, 52, 53, 54 are each assigned to a cylinder 21, 22, 23, 24, as can be seen, for example, in FIG. 1 or in FIG. 2, or one of the respective cylinders 21, 22, 23, 24 associated inlet flow path 31, 32, 33, 34.

In the embodiment variant shown in FIG. 3c, the exhaust gas cooling device 8 has an exhaust gas cooler 80 with a distributor space 802 arranged in the region of an exhaust gas inlet 801 in the exhaust gas cooler 80. The exhaust gas cooler 80 has a multiplicity of flow channels 100 between the distributor space 802 and an exhaust gas outlet region 803 from the exhaust gas cooler 80, the individual flow channels 100 being separated in terms of flow.

In each case a group A, B, C, D with at least two flow channels 100 is assigned to a cylinder-selective exhaust gas recirculation path 51, 52, 53, 54. The flow channels 100 of each group A, B, C, D open in the exhaust gas outlet region 803 of the exhaust gas cooler 80 into a respective collecting space 804A, 804B, 804C, 804D. From each plenum 804A; 804B; 804C; 804D, an assigned cylinder-selective exhaust gas recirculation path 51, 52, 53, 54 starts. The multi-flow exhaust gas cooler 80 thus has several flows per exhaust gas recirculation path 51, 52, 53, 54 and thus per cylinder 21, 22, 23, 24.

The line 11 in FIGS. 3a to 3c indicates the boundary between a condensation-free area and a condensation-prone area, with the condensation-free area on the left of the boundary 11 in FIGS. 3a to 3c and the condensation-free area on the right condensation-prone area is located. The position of this limit 11 can change depending on the operating point and the ambient conditions. The boundary 11 drawn in FIGS. 3a to 3c represents the earliest start of condensation in the operating temperature state. It can be clearly seen that in each of the embodiment variants shown in FIGS. 3a, 3b and 3c the division of the exhaust gas recirculation flow path 50 into flow channels 100 ; 101, 102, 103, 104 and / or in cylinder-selective exhaust gas recirculation paths 51; 52; 53; 54 already takes place in a condensation-free area of the exhaust gas cooling device 8.

With the solution according to the invention, the condensate formed in an exhaust gas recirculation system 5 can be fed to the cylinders selectively and a uniform supply of the cylinders can be achieved. While an application is particularly suitable for naturally aspirated engines - e.g. in a hybrid arrangement - turbo engines, e.g. with high-pressure exhaust gas recirculation, can also be improved.

Claims (10)

Claims 1. Internal combustion engine (1) with several cylinders (21, 22, 23, 24), an intake system (3), an exhaust system (4) and an exhaust gas recirculation system (5) for recirculating exhaust gas from the exhaust system (4) into the intake system ( 3), the exhaust gas recirculation system (5) having at least one exhaust gas recirculation flow path (50) in which at least one exhaust gas cooling device (8) with at least one exhaust gas cooler (80; 81, 82, 83, 84) is arranged, the exhaust gas recirculation flow path (50) in which or upstream of the exhaust gas cooling device (8) is divided into partial exhaust gas flows and the partial exhaust gas flows for cylinder-selective exhaust gas recirculation are guided in cylinder-selective exhaust gas recirculation paths (51, 52, 53, 54), with each cylinder (21, 22, 23, 24) at least one cylinder-selective exhaust gas recirculation path ( 51, 52, 53, 54), which enters an inlet flow path (31, 32, 33, 34) of the associated cylinder (21, 22, 23, 24) or directly into the associated cylinder (21, 22, 23, 24 ) einmün det, characterized in that the exhaust gas cooling device (8) has an exhaust gas cooler (80) with a distributor space (802), the exhaust gas cooler (80) having several flow channels between the distributor space (802) and an exhaust gas outlet area (803) from the exhaust gas cooler (80) (100; 101, 102, 103, 104), the individual flow channels (100; 101, 102, 103, 104) are separated in terms of flow, and that a group (A, B, C, D) of at least two flow channels (100) is assigned to a cylinder-selective exhaust gas recirculation path (51, 52, 53, 54) and the assigned cylinder-selective exhaust gas recirculation path (51, 52, 53, 54) in the exhaust gas outlet area (803) of the exhaust gas cooler (80) starts from a collecting chamber (804A, 804B, 804C, 804D) assigned to the cylinder-selective exhaust gas recirculation path (51, 52, 53, 54), in which the flow channels (100) of a group (A, B, C, D) open. 2. Internal combustion engine (1) according to claim 1, characterized in that the exhaust gas cooling device (8) has a plurality of exhaust gas coolers (81, 82, 83, 84), with each exhaust gas recirculation path (51, 52, 53, 54) at least one exhaust gas cooler (81, 82, 83, 84), and the exhaust gas recirculation flow path (50) is divided into the parallel flow through cylinder-selective exhaust gas recirculation paths (51, 52, 53, 54) upstream of the exhaust gas cooler (81, 82, 83, 84). 3. Internal combustion engine (1) according to claim 1, characterized in that the distributor space (802) is arranged in the region of an exhaust gas inlet (801) in the exhaust gas cooler (80). 4. Internal combustion engine (1) according to one of claims 1 to 3, characterized in that in each case a flow channel (101, 102, 103, 104) is assigned to a cylinder-selective exhaust gas recirculation path (51, 52, 53, 54) and the associated cylinder-selective exhaust gas recirculation path ( 51, 52, 53, 54) in the exhaust gas outlet region (803) of the exhaust gas cooler (80) starts from this associated flow channel (101, 102, 103, 104). 5. Internal combustion engine (1) according to one of claims 1 to 4, characterized in that the exhaust gas recirculation flow path (50) is divided in a condensation-free region of the exhaust gas cooling device (8). 6. Internal combustion engine (1) according to one of claims 1 to 5, characterized in that the differences in length between at least two adjacent cylinder-selective exhaust gas recirculation paths (51, 52, 53, 54) between the division of the exhaust gas recirculation flow path (50) and each of the opening into the inlet flow path (31, 32, 33, 34) or in the cylinder (21, 22, 23, 24) a maximum of 10%, preferably a maximum of 5%, particularly preferably a maximum of 2% of the length of the longest exhaust gas recirculation path (51, 52, 53, 54) be. 7. Internal combustion engine (1) according to one of claims 1 to 6, characterized in that at least two - preferably all - cylinder-selective exhaust gas recirculation paths (51, 52, 53, 54) have approximately the same length and / or the same cross section. 8. Internal combustion engine (1) according to one of claims 1 to 7, characterized in that at least one cylinder-selective exhaust gas recirculation path (51, 52, 53, 54) - is formed thermally insulated - at least in sections. 9. Internal combustion engine (1) according to one of claims 1 to 8, characterized in that the oscillation lengths of the cylinder-selective exhaust gas recirculation paths (51, 52, 53, 54) are related to the oscillation length of the inlet flow paths (31, 32, 33, 34) of the internal combustion engine (1 ) are matched. 10. Internal combustion engine (1) according to one of claims 1 to 9, characterized in that the exhaust gas cooling device (8) is arranged between an inlet manifold (30) of the inlet system (3) and the cylinders (21, 22, 23, 24). In addition 3 sheets of drawings