JP2007032394A - V type engine - Google Patents

Abstract

An object of the present invention is to solve the problem of exhaust interference in a V-type engine and to greatly improve turbine efficiency and EGR distribution.
An appropriate cylinder 4 is extracted from the cylinder row 2 distributed to the left and right so that half of the cylinder groups are configured so that the exhaust strokes do not overlap with each other at substantially equal intervals, and are divided into two groups. The exhaust systems are grouped and connected individually to the turbines 9 of the pair of turbochargers 8 provided for each of the left and right cylinder rows 2.
[Selection] Figure 1

Description

  The present invention relates to a V-type engine.

  FIG. 6 shows an example of the configuration of an intake system in a conventional V-type engine. In FIG. 6, reference numeral 1 denotes a V-type engine in which a pair of cylinder rows 2 are distributed so as to form a V-shape around a crankshaft (not shown) (In FIG. 6, the case of a V-type 8-cylinder engine composed of eight cylinders 4 as indicated by # 1 to # 8 is illustrated), and the left and right cylinder rows 2 of the V-type engine 1 are shown. The intake air 5 is introduced into each cylinder 4 through the intake manifold 3 arranged corresponding to each cylinder row 2.

  Then, the exhaust gas 6 discharged from each cylinder 4 is sent to the turbine 9 of a separate turbocharger 8 via the exhaust manifold 7 for each cylinder row 2 to collect exhaust energy and then to the outside of the vehicle through the exhaust pipe 10. It is supposed to be discharged.

  Further, in the example shown here, the vicinity of the inlet of the turbine 9 of each turbocharger 8 and each intake manifold 3 are connected by EGR pipes 11, respectively. An EGR valve 12 that appropriately opens and closes each EGR pipe 11 and an EGR cooler 13 for cooling the recirculated exhaust gas 6 are provided.

  That is, this type of EGR (Exhaust Gas Recirculation) system is provided, and if a part of the exhaust gas 6 is extracted from the exhaust side and returned to the intake side, the exhaust gas 6 returned to the intake side is used. By suppressing combustion of fuel in each cylinder 4 and lowering the combustion temperature, it becomes possible to reduce the generation of NOx. In particular, when the exhaust gas 6 to be recirculated is cooled by the EGR cooler 13, the exhaust gas 6 By reducing the temperature and reducing the volume of the engine, it becomes possible to reduce the combustion temperature and reduce the generation of NOx effectively without significantly reducing the engine output.

In addition, as the prior art document information related to the above-described V-type engine, for example, the following Patent Document 1 exists.
Japanese Patent Laid-Open No. 10-8951

  However, in such a V-type engine 1, the exhaust timings of the cylinders 4 of # 1 to # 4 in the left bank are as shown in FIG. 7, and the ignition order of the four cylinders 4 is # 1 → # 4 → Although # 2 → # 3, the exhaust timing of cylinder # 4 and cylinder # 4 are too close to each other and the exhaust strokes overlap each other. Therefore, in the region indicated by the hatched portion in FIG. Exhaust interference occurs, and due to this exhaust interference, the pressure of the exhaust gas 6 in the turbine 9 and the EGR pipe 12 drops as shown in FIG. 8, and the turbine efficiency and EGR distribution characteristics (uniform mixing of the recirculated exhaust gas 6 to the intake air 5) The horizontal axis in FIGS. 7 and 8 indicates the crank angle, the vertical axis in FIG. 7 indicates the lift of the exhaust valve, and the vertical axis in FIG. 8 indicates the exhaust gas pressure. .

  On the other hand, the exhaust timings of the cylinders 4 of # 5 to # 8 in the right bank are as shown in FIG. 9, and the ignition order of the four cylinders 4 is # 6 → # 5 → # 8 → # 7. However, since the exhaust timings of the cylinder # 4 and the cylinder # 5 are too close to each other and the exhaust strokes overlap each other, exhaust interference occurs in the region indicated by the hatched portion in FIG. The pressure of the exhaust gas 6 in the turbine 9 and the EGR pipe 12 dropped as shown in FIG. 10 due to the interference, causing the same problem as on the left bank side (the horizontal axis in FIGS. 9 and 10 is the crank angle, the vertical axis in FIG. 9). The axis represents the lift of the exhaust valve, and the vertical axis in FIG. 10 represents the pressure of the exhaust gas).

  In the present invention, the slight overlap between the closing of the exhaust valve in FIGS. 7 and 9 and the start of opening of the exhaust valve of another cylinder 4 is not regarded as the overlap of the exhaust stroke. Only when the main regions of the exhaust strokes overlap each other to such an extent that substantial exhaust interference can occur, the exhaust strokes are defined as overlapping.

  As shown in FIG. 11, a dual type exhaust manifold 7 (refer to the above-mentioned patent document 1) is employed to solve such an exhaust interference problem, and each cylinder 4 in the left bank overlaps the exhaust stroke in the left bank. The exhaust system is divided into two groups, # 1, # 2 and # 3, # 4, and is introduced into the turbine 9 of one turbocharger 8 separately for each group, and each cylinder in the right bank 4 is divided into two groups, # 5, # 8 and # 6, # 7, in which the exhaust stroke does not overlap in the right bank, and the exhaust system is divided into two systems, and the turbine 9 of the other turbocharger 8 is separately provided for each group. It is already known as a well-known technique.

  In this way, the pressure drop of the exhaust gas 6 in the turbine 9 and the EGR pipe 12 is somewhat mitigated as shown in FIG. 12 (left bank) and FIG. 13 (right bank). Exhaust interference is unavoidable, and a fundamental solution to the problem related to exhaust interference has not been achieved.

  In other words, if the interior of each turbine 9 as well as the exhaust system can be divided into two systems, it is considered that exhaust interference can be substantially avoided. However, in a turbo engine equipped with an EGR system in recent years, a turbocharger can be avoided. 8 is a variable nozzle type, and in such a variable nozzle type turbocharger 8, a number of nozzle vanes surrounding the turbine impeller are divided into two with a partition wall interposed therebetween, and each nozzle vane is placed on both sides of the partition wall. Since it is technically difficult to change the angle with the variable nozzle type turbocharger 8, it is a fact that the dual system inside the turbine 9 in the variable nozzle type turbocharger 8 has not yet been realized.

  The reason why the variable nozzle type turbocharger 8 is indispensable for the turbo engine is that the intake side is supercharged and the pressure difference from the exhaust side is reduced, making it difficult to achieve a high EGR rate. This is because it is necessary to ensure a pressure difference from the intake side by appropriately reducing the exhaust gas 6 on the side and increasing the pressure on the exhaust side.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to solve the problem of exhaust interference in a V-type engine and to greatly improve turbine efficiency and EGR distribution.

  The present invention extracts appropriate cylinders so that two or more cylinder groups are configured so that the exhaust strokes do not overlap with each other and are continued at substantially equal intervals from the left and right cylinder rows, and are divided into two groups. The present invention relates to a V-type engine characterized in that an exhaust system is individually connected for each group to a pair of turbocharger turbines installed for each left and right cylinder row.

  Thus, in this way, the exhaust stroke between the cylinders does not overlap in each of the exhaust systems connected to each turbine without dividing the inside of the turbine of each turbocharger into two systems. Exhaust interference in the turbine of the turbocharger is reliably avoided, the pressure of exhaust gas in the turbine does not drop, exhaust energy is efficiently recovered by the turbine, and the turbine efficiency is greatly improved.

  Further, in the present invention, it is preferable that an EGR system that recirculates a part of the exhaust gas to the intake side is individually provided in the exhaust system grouped for each group. It is efficiently fed into the EGR system and is effectively mixed and introduced into the intake air, so that exhaust gas recirculation that is more efficient than the conventional one is realized, and the EGR distribution is greatly improved.

  According to the V-type engine of the present invention described above, various excellent effects as described below can be obtained.

  (I) According to the invention described in claim 1 of the present invention, exhaust interference in the turbine of each turbocharger can be surely avoided, so that exhaust energy is efficiently recovered by the turbine without losing exhaust energy as much as possible. The turbine efficiency can be greatly improved.

  (II) According to the invention described in claim 2 of the present invention, exhaust pulsation can be efficiently fed into the EGR system and mixed and introduced into the intake air effectively. This can be realized and the EGR distribution can be greatly improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIGS. 1-5 shows an example of the form which implements this invention, and the part which attached | subjected the code | symbol same as FIGS. 6-13 represents the same thing.

  As shown in FIG. 1, in this embodiment, an appropriate number of cylinder groups are configured so that the exhaust strokes are continuous at substantially equal intervals without overlapping each other from the cylinder row 2 distributed to the left and right banks. The cylinders 4 are extracted and divided into two groups, and the exhaust systems are collectively connected to the turbines 9 of the pair of turbochargers 8 installed in the left and right cylinder rows 2 individually for each group. .

  More specifically, a dual-type exhaust manifold 7 is employed, and the cylinders 2 of the cylinder row 2 distributed to the left bank are consecutive in the same bank without overlapping the exhaust strokes # 1, # The exhaust system is divided into two groups, 4 and # 2, # 3, and the cylinders 2 in the cylinder row 2 allocated to the right bank are continuously connected without overlapping the exhaust stroke in the same bank. The exhaust system is divided into two groups # 5, # 8 and # 6, # 7, and the exhaust strokes do not overlap each other in each cylinder row 2 of the left and right banks and are continuously arranged at substantially equal intervals. Groups, that is, groups # 2, # 3 and # 5, # 8 (see FIG. 2), and groups # 1, # 4, # 6, and # 7 (see FIG. 3). Combined with each other, the exhaust system is divided into two systems, and a group consisting of # 2, # 3 and # 5, # 8 is combined. Is connected to the turbine 9 of one turbocharger 8 and the exhaust system of the group consisting of # 1, # 4 and # 6, # 7 is connected to the turbine 9 of the other turbocharger 8. Yes.

  Thus, even if the inside of the turbine 9 of each turbocharger 8 is not divided into two systems in this way, the exhaust strokes between the cylinders 4 do not overlap in each exhaust system. Exhaust interference in the turbine 9 is reliably avoided, and the pressure drop of the exhaust gas 6 in the turbine 9 and the EGR pipe 12 does not occur as shown in FIG. 4 (left bank) and FIG. 5 (right bank). Exhaust energy is efficiently recovered by the turbine 9 to significantly improve the turbine efficiency, and exhaust pulsation is efficiently fed into the EGR pipe 11 constituting the EGR system and effectively mixed and introduced into the intake air 5. Thus, exhaust gas recirculation that is more efficient than in the past is realized, and the EGR distribution is greatly improved.

  Therefore, according to the above embodiment, the exhaust interference in the turbine 9 of each turbocharger 8 can be avoided reliably, so that the exhaust energy can be efficiently recovered by the turbine 9 without losing as much as possible. Turbine efficiency can be greatly improved, and exhaust pulsation can be efficiently fed into the EGR system and mixed and introduced into the intake air 5 effectively, so that more efficient exhaust gas recirculation can be realized. Thus, the EGR distribution can be greatly improved.

  Note that the V-type engine of the present invention is not limited to the above-described embodiments, and can be applied to a V-type engine having no EGR system, and does not depart from the gist of the present invention. Of course, various changes can be made within the range.

It is the schematic which shows an example of the form which implements this invention. It is a graph which shows the exhaust timing of each cylinder in one group of FIG. 2 is a graph showing the exhaust timing of each cylinder in the other group of FIG. 1. It is a graph which shows the pressure fluctuation of the exhaust gas in one group of FIG. It is a graph which shows the pressure fluctuation of the exhaust gas in the other group of FIG. It is the schematic which shows a prior art example. It is a graph which shows the exhaust timing of each cylinder of the left bank of FIG. It is a graph which shows the pressure fluctuation of the exhaust gas in the left bank of FIG. It is a graph which shows the exhaust timing of each cylinder of the right bank of FIG. It is a graph which shows the pressure fluctuation of the exhaust gas in the right bank of FIG. It is the schematic which shows another prior art example. It is a graph which shows the pressure fluctuation of the exhaust gas in the left bank of FIG. It is a graph which shows the pressure fluctuation of the exhaust gas in the right bank of FIG.

Explanation of symbols

1 V type engine 2 cylinder row 4 cylinder 6 exhaust gas 7 exhaust manifold (exhaust system)
8 Turbocharger 9 Turbine 11 EGR pipe (EGR system)

Claims (2)

  Appropriate cylinders are extracted from the cylinder rows distributed to the left and right so that the exhaust strokes do not overlap with each other and are arranged at approximately equal intervals, and divided into two groups. A V-type engine characterized in that an exhaust system for each group is individually connected to a pair of turbocharger turbines installed for each group.   2. The V-type engine according to claim 1, wherein an EGR system that recirculates a part of the exhaust gas to the intake side is individually provided in an exhaust system that is grouped for each group. 3.

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