JP2007154818A - Cooling device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling device for an internal combustion engine improving deterioration of exhaust emission at the time of engine start further in the multiple cylinder internal combustion engine. <P>SOLUTION: These devices are the cooling devices 10a, 10b for the multiple cylinder internal combustion engine operating part of cylinders at the time of engine start. When only part of the cylinders 1a are operated at the time of engine start, a fixed quantity of cooling water is circulated around the part of the cylinders but is not circulated around cylinders 1b other than the part of the cylinders 1a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cooling device for an internal combustion engine.

  When the engine is started, since the engine body is not warmed up, fuel vaporization in the cylinder becomes insufficient, and the exhaust gas contains a relatively large amount of unburned fuel. In addition, since the engine exhaust system catalyst device is not warmed up, the exhaust gas containing such a relatively large amount of unburned fuel cannot be sufficiently purified, and the exhaust emission is greatly deteriorated. To do.

  Accordingly, it has been proposed to improve the deterioration of exhaust emission by operating only some cylinders of a multi-cylinder internal combustion engine and reducing the amount of exhaust gas when starting the engine (see, for example, Patent Document 1). .

JP 2003-148185 A JP 2004-346903 A 7-4841 JP 2000-356133 A

  According to the above-described technique, it is true that the amount of exhaust gas including a large amount of unburned fuel at the time of starting the engine is reduced and the deterioration of exhaust emission is improved as compared with the case where all cylinders are operated at the time of starting the engine. be able to. However, by devising a cooling device for an internal combustion engine, it is possible to further improve the deterioration of exhaust emission.

  Accordingly, an object of the present invention is to provide a cooling device for an internal combustion engine for further improving deterioration of exhaust emission at the time of engine start in a multi-cylinder internal combustion engine.

  The cooling device for an internal combustion engine according to claim 1 of the present invention is a cooling device for a multi-cylinder internal combustion engine that operates only a part of the cylinders when the engine is started, and only the part of the cylinders is operated when the engine is started. When the engine is in operation, a certain amount of cooling water circulates around the partial cylinders and does not circulate around cylinders other than the partial cylinders.

  A cooling device for an internal combustion engine according to a second aspect of the present invention is the cooling device for an internal combustion engine according to the first aspect, wherein the cooling water circulation passage around the partial cylinder and the cooling around the cylinders other than the partial cylinder are provided. The water circulation passages are formed independently of each other.

  According to a third aspect of the present invention, there is provided a cooling device for an internal combustion engine according to the first aspect, wherein the cooling water circulation passage around the partial cylinder and the cooling around the cylinders other than the partial cylinder are provided. The water circulation passage communicates with each other via an on-off valve.When only the part of the cylinders is in operation at the time of engine start, by closing the on-off valve, the fixed amount of cooling water is It circulates around the partial cylinders and does not circulate around cylinders other than the partial cylinders.

  According to the cooling device for an internal combustion engine according to claim 1 of the present invention, when only a part of the cylinders is operated at the time of starting the engine, a certain amount of cooling water circulates around the part of the cylinders, It is designed not to circulate around cylinders other than cylinders. Thereby, a certain amount of cooling water circulates only around some of the operating cylinders, so that the temperature rises early, and some cylinders are warmed up early. In this way, when the engine is started, the fuel vaporization in the cylinders of some of the operating cylinders becomes good early and the amount of unburned fuel contained in the exhaust gas is reduced. Even if the warm-up of the engine is insufficient, the amount of unburned fuel released into the atmosphere is reduced, and the exhaust emission at the start of the engine can be improved.

  According to the cooling device for an internal combustion engine according to claim 2 of the present invention, in the cooling device for the internal combustion engine according to claim 1, cooling water circulation passages around some cylinders and cooling around cylinders other than some cylinders The water circulation passages are formed independently of each other. Thereby, in order to circulate only around a part of the operating cylinders through a coolant circulation passage around a part of the cylinders at the time of starting the engine without requiring any particular control. An effect similar to that of the cooling apparatus for an internal combustion engine according to claim 1 can be obtained. If necessary, circulation of the cooling water may be stopped in the cooling water circulation passage around the cylinders other than some cylinders.

  According to the cooling device for an internal combustion engine according to claim 3 of the present invention, in the cooling device for the internal combustion engine according to claim 1, cooling water circulation passages around some cylinders and cooling around cylinders other than some cylinders The water circulation passage communicates with each other via an on-off valve, and closes the on-off valve when only a part of the cylinders is operated at the time of engine start. Accordingly, at the time of starting the engine, a certain amount of cooling water circulates only around the operating part of the cylinders through the cooling water circulation passage around the part of the cylinders. The same effect as that of the cooling device can be obtained. In addition, when the partial cylinder operation at the start of the engine is finished and the full cylinder operation is started, if the on-off valve is opened, the cooling water circulation passage around some cylinders and the cooling around the cylinders other than some cylinders are cooled. The water circulation passage is communicated. Accordingly, at this time, a certain amount of cooling water whose temperature has already increased in the cooling water circulation passages around some cylinders also circulates in the cooling water circulation passages around the cylinders other than some cylinders. The warm-up of cylinders other than the partial cylinders can be accelerated.

  FIG. 1 is a schematic view showing a first embodiment of a cooling device for an internal combustion engine according to the present invention. In the present embodiment, the internal combustion engine is a V-type internal combustion engine. In FIG. 1, 1a is a first bank of a V-type internal combustion engine, and 1b is a second bank. 2a is a first intake manifold of the first bank 1a, and 2b is a second intake manifold of the second bank 1b. A first intake passage 3a is connected to the first intake manifold 2a, and a second intake passage 3b is connected to the first intake manifold 2b. Throttle valves 4a and 4b are arranged in the first intake passage 3a and the second intake passage 3b, respectively, and the intake air amounts of the first bank 1a and the second bank 1b can be controlled independently of each other.

  5a is a first exhaust manifold of the first bank 1a, and 5b is a second exhaust manifold of the second bank 1b. A first exhaust passage 6a is connected to the first exhaust manifold 5a, and a second exhaust passage 6b is connected to the second exhaust manifold 5b. The first exhaust passage 6 a and the second exhaust passage 6 b merge at the exhaust merging portion 7, and the main catalyst device 8 is disposed downstream of the exhaust merging portion 7.

  The present V-type internal combustion engine mainly operates at a stoichiometric air-fuel ratio, and a three-way catalyst device is selected as the main catalyst device 8. Although the main catalyst device 8 is relatively large, there is no problem of vehicle mountability because it is disposed under the vehicle floor. Thus, a large amount of exhaust gas discharged from each cylinder at the time of high engine load can be purified well by the main catalyst device 8. However, the exhaust gas discharged from each cylinder when the engine is under a low load has a relatively low temperature. When the exhaust gas flows into the main catalyst device 8, the temperature further decreases, so that the main catalyst device 8 is brought to the catalyst activation temperature. It cannot be maintained, and exhaust gas purification becomes insufficient.

  Therefore, in the present embodiment, the first sub catalyst device 9a is disposed as the three-way catalyst device in the first exhaust passage 4a, and the second sub catalyst device 9b is disposed as the three-way catalyst device in the second exhaust passage 4b. Has been. Thereby, even if the first bank 1a and the second bank 1b are operated at the time of engine low load, the first sub-catalyst device 9a and the second sub-catalyst 9a and the second sub-catalyst do not decrease the temperature of the exhaust gas having relatively low temperature. In order to flow into the apparatus 9b, the catalyst carried on each is maintained at the activation temperature, and the exhaust gas at this time can be sufficiently purified.

  10a is a first cooling water circulation passage formed in the cylinder block of the first bank 1a, and 10b is a second cooling water circulation passage formed in the cylinder block of the second bank 1b. An inlet pipe 11a and an outlet pipe 12a are connected to the first cooling water circulation passage 10a, and the cooling water supplied from the inlet pipe 11a through a circulation pump (not shown) passes through the first cooling water circulation passage 10a. When discharging from 12a, each cylinder of the first bank 1a is cooled. Further, an inlet pipe 11b and an outlet pipe 12b are connected to the second cooling water circulation passage 10b, and the cooling water supplied from the inlet pipe 11b through a circulation pump (not shown) passes through the second cooling water circulation passage 10b. When discharging from the outlet pipe 12b, each cylinder of the second bank 1b is cooled.

  By the way, since the engine temperature is low when the engine is started, the fuel is difficult to vaporize in the cylinder, and the exhaust gas contains a relatively large amount of unburned fuel. Sub-catalyst devices 9a and 9b are arranged near each bank, but these sub-catalyst devices 9a and 9b also do not rise to the catalyst activation temperature immediately after the cranking starts, and unburned fuel. Exhaust gas containing a large amount of gas is not sufficiently purified by the sub-catalyst device and is released into the atmosphere, resulting in a very worse exhaust emission.

  In this embodiment, at the time of engine start, for example, from the start of cranking to a set time after the start is completed, or from the start of cranking until the required engine load becomes equal to or higher than the set load due to vehicle running, etc. Is a partial cylinder operation in which only the cylinders of the first bank 1a are operated and the fuel injection to the cylinders of the second bank 1b is stopped. As a result, exhaust gas containing a large amount of unburned fuel at the time of starting the engine is discharged only from the cylinders of the first bank 1a, and the amount of exhaust gas at the time of starting the engine can be reduced (halved). Even if the purification by is insufficient, the exhaust emission can be improved.

  In the present embodiment, the exhaust emission at the time of starting the engine can be further improved by the cooling device having the first cooling water circulation passage 10a and the second cooling water circulation passage 10b as described above. Since the first cooling water circulation passage 10a and the second cooling water circulation passage 10b are independent of each other including the circulation pump, by operating the circulation pump on the first cooling water circulation passage 10a side when starting the engine, A certain amount of cooling water circulating through the first cooling water circulation passage 10a rises quickly because it circulates only around the cylinders of the operating first bank 1a without passing through the radiator by a general thermostat structure. The cylinders in the first bank 1a are warmed up early. Thus, when the engine is started, the fuel vaporization in the cylinders of the cylinders of the first bank 1a during operation becomes good early and the amount of unburned fuel contained in the exhaust gas is reduced. Even if the catalyst device is not sufficiently warmed up, less unburned fuel is released into the atmosphere, and exhaust emission at the time of engine startup can be further improved.

  In the present embodiment, since the first cooling water circulation passage 10a and the second cooling water circulation passage 10b are independent of each other including the circulation pump, the circulation pump on the second cooling water circulation passage 10b side when the engine is started. The same effect as described above can be obtained regardless of whether it is operated or stopped. However, it does not make sense to circulate the cooling water in the second cooling water circulation passage 10b of the second bank 1b that is not operating when the engine is started. For example, the circulation pump and the second cooling water circulation passage on the first cooling water circulation passage 10a side. Except for the case where the circulation pump on the 10b side is driven by the same motor, it is preferable to reduce the power consumption by stopping only the circulation pump on the second cooling water circulation passage 10b side when starting the engine.

  When the start of the engine is completed and the operation of the second bank 1b is started, if the circulation pump on the second cooling water circulation passage 10b side is stopped, this is activated. Regarding the second bank 1b, the engine start is started from this time, but the main catalyst device 8 on the downstream side of the exhaust merging portion 7 has been discharged from each cylinder of the first bank 1a by this time. Exhaust gas has passed and a certain degree of catalytic activity has been realized, and part of the heat generated by the operation of each cylinder of the first bank 1a is transmitted to the second bank 1b by this time, The engine temperature of the second bank 1b is higher than that at the start of the engine start of the first bank 1a. Accordingly, the exhaust gas discharged from each cylinder of the second bank 1b does not contain so much unburned fuel, and the exhaust gas discharged from each cylinder of the second bank 1b Since the catalyst device 8 is purified to some extent, the exhaust emission does not deteriorate so much at the start of operation of each cylinder of the second bank 1b.

  FIG. 2 is a schematic view showing a second embodiment of the cooling device for an internal combustion engine according to the present invention. Only differences from the first embodiment will be described below. In the present embodiment, the first cooling water circulation passage 10 a and the second cooling water circulation passage 10 b are communicated by a communication pipe 13 in which an on-off valve 14 is disposed, and a single inlet pipe 15 from the circulation pump is connected to the communication pipe 13. The on-off valve 14 is connected to the first cooling water circulation passage 10a side.

  In the present embodiment, only one circulation pump is provided. When the first bank 1a is operated by a part of the cylinders, the circulation pump is operated simultaneously with the start of each cylinder, and the on-off valve 14 of the communication pipe 13 is set. Close the valve. Thus, when the engine is started and opened, a certain amount of cooling water passes through the first cooling water circulation passage 10a without passing through the radiator by a general thermostat structure, and only around the cylinders of the operating first bank 1a. In order to circulate, the temperature rises early, and the cylinders of the first bank 1a are warmed up early. Thus, when the engine is started, the fuel vaporization in the cylinders of the cylinders of the first bank 1a during operation becomes good early and the amount of unburned fuel contained in the exhaust gas is reduced. Even if the catalyst device is not sufficiently warmed up, less unburned fuel is released into the atmosphere, and exhaust emission at the time of engine startup can be further improved.

  Further, when the start of the engine is completed and the operation of the second bank 1b is started, the on-off valve 14 of the communication pipe 14 is opened. Regarding the second bank 1b, the engine start is started from this time, but the main catalyst device 8 on the downstream side of the exhaust merging portion 7 has been discharged from each cylinder of the first bank 1a by this time. Exhaust gas has passed and a certain degree of catalytic activity has been realized, and part of the heat generated by the operation of each cylinder of the first bank 1a is transmitted to the second bank 1b by this time, The engine temperature of the second bank 1b is higher than that at the start of the engine start of the first bank 1a. In addition, a certain amount of cooling water whose temperature has risen by cooling each cylinder of the first bank 1a is circulated to the second cooling water circulation passage 10b through the communication pipe 13 by opening the on-off valve 14. The warm-up of the second bank 1b can be accelerated.

  As a result, the exhaust gas discharged from each cylinder of the second bank 1b contains less unburned fuel than the first embodiment, and from each cylinder of the second bank 1b. Since the exhaust gas discharged is purified to some extent by the main catalyst device 8, the exhaust emission does not deteriorate so much at the start of operation of each cylinder of the second bank 1b.

In the two embodiments described above, the main catalytic converter 8 has been a three-way catalytic converter, when one in which the internal combustion engine carrying out the lean burn operation may be a NO _X catalyst device. In addition, the internal combustion engine performs the partial cylinder operation at the time of starting the engine, but, of course, the partial cylinder operation may be performed even at a low load other than at the time of starting the engine. For the partial cylinder operation other than the engine start, the second bank 1b may be used as the operating cylinder group.

  Although the internal combustion engine is V-shaped, this is not a limitation of the present invention. Even if a plurality of cylinders are arranged in series, a plurality of cylinders are operated when the engine is started and a cylinder group is stopped when the engine is started. If the cooling device enables a certain amount of cooling water to circulate around the cylinder group that is operated when the engine is started and not circulate around the cylinder group that is not operated when the engine is started, The invention can be applied.

1 is a schematic view showing a first embodiment of a cooling device for an internal combustion engine according to the present invention. It is the schematic which shows 2nd embodiment of the cooling device of the internal combustion engine by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a 1st bank 1b 2nd bank 7 Exhaust merge part 8 Main catalyst apparatus 9a 1st subcatalyst apparatus 9b 2nd subcatalyst apparatus 10a 1st cooling water circulation path 10b 2nd cooling water circulation path 13 Communication pipe 14 On-off valve

Claims (3)

  A cooling device for a multi-cylinder internal combustion engine that operates only some cylinders when the engine is started. When only the some cylinders are operated when the engine is started, a certain amount of cooling water flows around the some cylinders. A cooling device for an internal combustion engine, which circulates and does not circulate around the cylinders other than the partial cylinders.   2. The cooling apparatus for an internal combustion engine according to claim 1, wherein the cooling water circulation passage around the partial cylinder and the cooling water circulation passage around the cylinder other than the partial cylinder are formed independently of each other. .   The cooling water circulation passages around the partial cylinders and the cooling water circulation passages around the cylinders other than the partial cylinders communicate with each other via an on-off valve, and only the partial cylinders are operated when the engine is started. When the open / close valve is closed, the fixed amount of cooling water circulates around the partial cylinders and does not circulate around the cylinders other than the partial cylinders. The cooling device for an internal combustion engine according to claim 1.

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