Combustion engine with exhaust gas recirculation

Description

[0001] An internal combustion engine is known from DE 691 30 976 T2. This internal combustion engine has an exhaust gas recirculation system with a distribution line running parallel to a fresh gas line. The fresh gas line has branching fresh gas channels, each leading to the two intake valves of a cylinder unit. The distribution line opens into the fresh gas channels with individual feed lines. In known exhaust gas recirculation (EGR) coolers, the engine cooler is flowed transversely and is located in a kind of pocket directly in the engine crankcase without its own housing. The transverse flow allows the entire engine water volume to be made available to the EGR cooler due to the large flow cross-section. In contrast to longitudinal flow, the water also experiences a significantly lower temperature increase. Due to its functionality, this arrangement is ideal in terms of cooling effect and water-side pressure loss.

[0002] The problem with such arrangements is that the EGR cooler insert is not completely enclosed by the contour of the water pocket in the crankcase. As a result, a large amount of water flows around the EGR cooler, reducing the flow velocity through the cooler fins and thus diminishing the cooling effect.

[0003] Furthermore, EP 3 073 089 A1 discloses an internal combustion engine with at least one cooler having an exhaust gas inlet to the cooler and an integrated exhaust passage. The cooler is arranged in an inner cooling section of the crankcase, with projections cooperating with a cooler housing to ensure a turbulent flow of the coolant flowing around or between the projections and the cooler housing.

[0004] From EP 2 063 097 A1, an internal combustion engine is known, comprising: a cylinder housing element having a wall structure defining at least one cylinder chamber, and a cooling fluid jacket for cooling the cylinder housing element; and a gas channel extending at least partially within the cylinder housing element, such that the cooling fluid jacket reduces the temperature of a gas in the gas channel.

[0005] From DE 10 2004 015 487 A1 an internal combustion engine with a crankcase and a cylinder head is known, to which an exhaust manifold and a fresh gas line are attached, wherein the exhaust manifold and the fresh gas line are connected via an exhaust gas recirculation line to an exhaust gas recirculation control valve integrated into the exhaust gas recirculation line and an exhaust gas cooler consisting of an exhaust gas cooling line and a cooling housing, wherein the cooling housing is an integral part of the crankcase at least in a partial area.

[0006] The invention described below addresses this problem. The goal was to direct the water through the cooler and minimize leakage losses. At the same time, the solution should be implemented with minimal additional manufacturing and assembly costs.

[0007] The invention is based on the object of simplifying the installation of the exhaust gas recirculation device, in particular the distribution line, to the internal combustion engine and improving the cooling effect.

[0008] This object is achieved by an internal combustion engine having the features according to claim 1 and by a method having the features according to claim 6.

[0009] Firstly, cast fins are attached to the inlet ports of the EGR cooler, and secondly, cast ribs are inserted into the crankcase pocket. The cast ribs in the crankcase are brought up to the cast fins of the EGR cooler, with only a small gap, as shown in Fig. 1 This significantly reduces the leakage cross-section to the remaining gap. To reduce the tolerance-related variance in the gap width and thus the dispersion of the throttling effect, the cast fins on the crankcase side are machined. Due to the narrow fin width, only a small amount of material is removed, thus only slightly increasing the machining time for the crankcase. The cast fins on the EGR cooler, however, do not require machining, as the tolerances for die-casting are already sufficiently precise.

[0010] Another advantage here is that the internal combustion engine is extremely compact and that heat transfer can be carried out extremely effectively without unnecessary piping.

[0011] In a further development of the invention, it is provided that the cooling section has turbulence generators which ensure even better heat transfer.

[0012] In a further embodiment of the invention, orifices and / or throttle devices are inserted into the channels. These components allow for individual adjustment of the amount of exhaust gas supplied to the individual cylinder units.

[0013] This solution minimizes leakage losses. Conversely, flow velocities and thus the cooling effect at the EGR cooler are significantly increased or improved.

[0014] If the rear cast fin in the crankcase is extended along the entire length of the EGR cooler, the additional baffle on the rear of the EGR cooler can be omitted. This results in cost savings that should offset the additional costs for machining the fins on the crankcase.

[0015] Due to the ability to adapt the machining of the crankcase at any time, it is also possible to respond to design changes of the EGR cooler at any time.

[0016] Further advantageous embodiments of the invention can be found in the description of the drawings, in which exemplary embodiments of the invention are described in more detail. They show: Fig. 1 a perspective view of a crankcase with a cooling housing of an exhaust gas cooler of an exhaust gas recirculation device integrated into the crankcase, Fig. 2 a side view of the EGR cooler according to Fig. 1 , Fig. 3 a section through the crankcase from Fig. 1 with an EGR cooling housing, the base body of which is part of the crankcase and the base body is covered by a cover, Fig. 4 a section through the crankcase along the line CC from Fig. 3 .

[0017] Fig. 1 shows the cylinder block of the crankcase 1 of the internal combustion engine, which has a flat flange surface on its long side for receiving an EGR cooler 2. In the sealing plane of the flat flange surface, a coolant inlet opening 9 is provided in the region of one end face of the internal combustion engine, which coolant allows coolant to pass through to the cooler 2. In the immediate vicinity of the coolant inlet opening 9, the coolant outlet opening of the cooler 2 is also arranged in the sealing plane of the flange surface. In the sealing plane of the flat flange surface, an exhaust gas inlet to the cooler is provided in the region of the other end face of the internal combustion engine, which exhaust gases allow exhaust gases to pass through to the cooler. In the immediate vicinity of the exhaust gas inlet to the cooler, the integrated exhaust gas duct from the cooler is also arranged in the sealing plane of the flange surface.The internal cooling section has nose-shaped elevations which, in conjunction with flow guide elements arranged on the cooler housing, ensure a turbulent flow of the coolant flowing around or between the nose-shaped elevations and the flow guide elements. The gas is extracted from the cylinder head via the duct in the cylinder head and is passed on to the exhaust inlet via the exhaust gas inlet opening using a duct connection in the crankcase 1. The exhaust gas reaching the exhaust inlet is fed into the EGR line in the cooler 2, where it releases its waste heat to the coolant. The cooled exhaust gas then leaves the cooler 2 via the integrated exhaust gas duct through the crankcase 1 towards the exhaust system. A seal is arranged between the EGR cooler 2 and the flange surface.

[0018] In Fig. 2 is a side view of the EGR cooler 2 mounted in the crankcase 1 according to Fig. 1 This EGR cooler 2 has a cooler cassette 3 that acts as a cooling section. A guide plate 4 is arranged to support the cooling section of the cooler cassette 3. From the perspective of the exhaust gas flow direction, an inlet nozzle 5 and an outlet nozzle 8 are arranged upstream and downstream of the cooler cassette 3. The inlet nozzle 5 of the EGR cooler 2 has a cast fin 6. The outlet nozzle 8 of the EGR cooler 2 has a cast fin 6.

[0019] Fig. 3 shows a section through the crankcase 1 Fig. 1 with an EGR cooler 2 in a cooling housing, the base body of which is part of the crankcase 1 and wherein the base body is covered by a cover that is screwed to the crankcase 1. The guide plate 4, which is also flowed around by the cooling water, is arranged on the cooling section of the EGR cooler 2, around which the cooling water of the internal combustion engine flows. The cast fin 6, around which the cooling water of the internal combustion engine flows, can be seen at the inlet nozzle of the EGR cooler 2. Opposite the cast fin 6 of the EGR cooler 2, the cast rib 7 arranged on the crankcase 1 of the internal combustion engine can be seen. The arrangement of the cast fin 6 to the cast rib 7 leads to a gap in the cooling water-guided area of ​​the EGR cooler 2 when installed, which gap influences the flow velocity of the cooling water.

[0020] In Fig. 4 a section through the crankcase 1 along the line CC is taken from Fig. 3shown. Here, it becomes clear once again how the arrangement of the cast fin 6 on the inlet nozzle 5 in combination with the cast rib 7 arranged on the crankcase 1 of the internal combustion engine affects the flow conditions of the cooling water. List of reference symbols

[0021] 1Crankcase 2EGR cooler 3Cooler cassette 4Baffle 5Inlet nozzle 6Cast fin 7Cast rib 8Outlet nozzle 9Coolant inlet opening

Claims

1. Internal combustion engine with a crankcase (1) and a cylinder head, comprising at least one cylinder block, at least one flat flange surface to receive at least one EGR cooler (2), at least one EGR cooler (2), at least one coolant inlet port (9) to the EGR cooler (2), at least one coolant outlet port from the EGR cooler (2), at least one exhaust gas inlet to the EGR cooler (2), at least one exhaust gas leadthrough from the EGR cooler (2) and at least one cooler cassette (3) acting as a cooling section, wherein, in an exhaust flow direction, an inlet connection (5) is arranged upstream of the cooler cassette (3) and an outlet connection (8) is arranged downstream of the cooler cassette (3), characterized in that the inlet connection (5) and the outlet connection (8) each have a cast fin (6), wherein a cast rib (7) arranged on the crankcase (1) is provided opposite the cast fins (6), and the cast fin (6) is arranged with respect to the cast rib (7) in such a way that a gap in a cooling water-conducting area of the EGR cooler (2) is formed between them, which has an influence on the flow velocity of the cooling water.

2. Internal combustion engine according to Claim 1, characterized in that the cooler cassette (3) has turbulence generators.

3. Internal combustion engine according to one or more of the preceding claims, characterized in that the flat flange surface is arranged substantially on a longitudinal side of the crankcase (1) for receiving the EGR cooler (2).

4. Internal combustion engine according to one or more of the preceding claims, characterized in that the cast fin (6) and cast rib (7) act as orifices and / or throttle devices between the EGR cooler (2) and the crankcase (1).

5. Internal combustion engine according to one or more of the preceding claims, characterized in that the cast rib (7) on the crankcase (1) extends over the entire length of the EGR cooler (2) on the rear side.

6. Method for producing an internal combustion engine according to one or more of the preceding claims, characterized in that a tolerance-related variance of a width of the gap between the cast fin (6) and the cast rib (7) is brought about only by machining the cast rib (7) on the crankcase side.