JP5387984B2 - Internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine having a burner device for promoting warm-up of an exhaust purification catalyst in an exhaust passage.

  There is a case where a burner device is provided upstream of the exhaust purification catalyst in the exhaust passage of the internal combustion engine, and the exhaust purification catalyst is heated using the heating gas generated by the burner device to promote warming up of the exhaust purification catalyst. .

  In addition, there exists a thing disclosed by patent document 1 as a technique relevant to this. In this case, some cylinders of the multi-cylinder spark ignition engine are operated with a rich mixture, and the remaining cylinders are stopped to supply fuel and used as an air blower. Combustible gas generated in some cylinders and air supplied from the remaining cylinders are mixed to form a combustible mixture. This combustible air-fuel mixture is burned in a combustor having an ignition mechanism such as a spark plug, and the downstream catalyst is heated.

JP 08-170525 A

  The burner device supplies fuel into the gas in the exhaust passage, ignites the gas / fuel mixture by an appropriate ignition means, and burns it. Therefore, unless the oxygen concentration of the gas is sufficiently high, ignition tends to be impossible.

  On the other hand, some internal combustion engines have a turbocharger. In this case, it is conceivable to install a burner device on the downstream side of the turbine. However, in this case, the gas that has passed through the turbine and heated by the turbine is supplied to the burner device. When the gas is heated, its oxygen concentration naturally decreases, which is not suitable for the burner apparatus.

  Therefore, an object of the present invention is to provide an internal combustion engine that can operate a burner device satisfactorily even when a turbocharger is provided.

According to one aspect of the invention,
A first exhaust passage is connected to some cylinders of the multi-cylinder internal combustion engine, a second exhaust passage is connected to the remaining cylinders of the internal combustion engine, and the first and second exhaust passages are connected to the downstream end. To gather together to form a gathering passage,
A turbocharger turbine is disposed in the first exhaust passage;
The rest of the cylinders can be stopped independently of the some cylinders by stopping fuel injection,
An internal combustion engine is provided in which a burner device having a fuel supply nozzle, a glow plug and an oxidation catalyst is disposed in the second exhaust passage.

  When the remaining cylinders are deactivated, the remaining cylinders function as an air pump that discharges intake air as it is. The air discharged from the remaining cylinders is supplied to the burner device without passing through the turbine. Therefore, it is possible to prevent the heating of the air by the turbine, and hence the decrease in the oxygen concentration of the air, and to operate the burner device efficiently.

  Preferably, the burner device is activated when the remaining cylinders are deactivated.

  Preferably, an exhaust purification catalyst is disposed in the collecting passage.

  According to the present invention, it is possible to provide an internal combustion engine capable of operating the burner device satisfactorily even when a turbocharger is provided.

1 is a diagram schematically showing an internal combustion engine according to an embodiment of the present invention. It is a flowchart which shows an example of control.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

  FIG. 1 schematically shows an internal combustion engine according to an embodiment of the present invention. Reference numeral 1 denotes a compression ignition type internal combustion engine or diesel engine for automobiles, 2 denotes an intake manifold communicated with an intake port, and 4 denotes a combustion chamber defined by a cylinder and a piston. In the present embodiment, fuel supplied from a fuel tank (not shown) to the high-pressure pump 5 is pumped to the common rail 6 by the high-pressure pump 5 and accumulated in a high-pressure state. 4 is directly supplied by injection. In addition, as a form of a diesel engine, it is not restricted to the thing provided with such a common rail type fuel injection device.

  The intake air introduced from the air cleaner 10 into the intake passage 11 passes through the air flow meter 12, the compressor C of the turbocharger 8, the intercooler 13, and the throttle valve 14 in order to reach the intake manifold 2. The air flow meter 12 is a sensor for detecting the amount of intake air. The throttle valve 14 is an electronically controlled type.

  The exhaust system of the engine 1 is configured as follows. First, the engine 1 is a multi-cylinder engine, specifically an in-line four-cylinder engine, in which the cylinders # 1 to # 4 are arranged in order from the left side in the drawing. The first exhaust passage 31 is connected to the # 1 and # 4 cylinders located at both ends, and the second exhaust passage 32 is connected to the # 2 and # 3 cylinders located at the intermediate portion. .

  The first exhaust passage 31 is branched at the upstream end and is individually connected to the # 1 and # 4 cylinders, and the downstream side is gathered from the upstream end. A turbine T of the turbocharger 8 is disposed in the middle of the collecting portion 31 </ b> A of the first exhaust passage 31.

  The second exhaust passage 32 is also branched at the upstream end portion and individually connected to the # 2 and # 3 cylinders, and the downstream side is gathered from the upstream end portion. A burner device 40, which will be described in detail later, is disposed in the middle of the collecting portion 32A of the second exhaust passage 32.

  The downstream end portion of the collecting portion 31A of the first exhaust passage 31 and the downstream end portion of the collecting portion 32A of the second exhaust passage 32 are gathered at the merging position X, and the collecting passage 33 is arranged downstream of the merging position X. Form. An exhaust purification catalyst 34 is disposed in the middle of the collecting passage 33.

  The exhaust purification catalyst 34 in the present embodiment is a NOx catalyst that reduces and purifies NOx in the exhaust. The NOx catalyst may be an occlusion reduction type or a selective reduction type. Preferably, a plurality of exhaust purification catalysts are provided, and in addition to the NOx catalyst, an oxidation catalyst for oxidizing and purifying unburned components (particularly HC) in the exhaust is provided. In addition, a particulate filter (hereinafter referred to as DPF) that collects particulates (PM, particulates) such as soot in the exhaust is provided. Some DPFs continuously oxidize and burn fine particles collected by supporting a catalyst made of a noble metal, and these catalysts are also included in the exhaust purification catalyst. In particular, in the case of a spark ignition type internal combustion engine, the exhaust purification catalyst may be a three-way catalyst.

  The burner device 40 is for generating heated gas, supplying the generated heated gas to the exhaust purification catalyst 34 on the downstream side, and maintaining and promoting the warming up and the active state of the exhaust purification catalyst 34. The burner device 40 includes a fuel supply nozzle 41, a glow plug 42, and an oxidation catalyst 43, which are arranged from the upstream side.

  During operation of the burner device 40, fuel is injected from the fuel supply nozzle 41 into the exhaust passage 32, and the glow plug 42 is energized. Then, a rich air-fuel mixture composed of the fuel supplied from the fuel supply nozzle 41 and the gas existing in the exhaust passage 32 is ignited or at least oxidized by the glow plug 42. The ignited or oxidized air-fuel mixture passes through the oxidation catalyst 43, where it is further combusted or oxidized.

  In this way, high-temperature heated gas is discharged from the oxidation catalyst 43, and by supplying this heated gas to the exhaust purification catalyst 34, it is possible to maintain and promote the warm-up and active state of the exhaust purification catalyst 34. It becomes. In particular, the burner device 40 is advantageous for improving cold emission immediately after the cold start of the engine.

  Here, the oxidation catalyst 43 is configured to occupy a partial cross-sectional area of the exhaust passage 32. Accordingly, only part of the gas in the exhaust passage 32 passes through the oxidation catalyst 43, and the gas flow rate inside the oxidation catalyst 43 is lower than the gas flow rate outside. Therefore, a sufficient reaction time can be secured inside the oxidation catalyst 43, which is advantageous for raising the temperature of the heated gas. When the oxidation catalyst 43 is sufficiently hot, the glow plug 42 may be stopped and the air-fuel mixture may be directly combusted in the oxidation catalyst 43. On the other hand, when the oxidation catalyst 43 is not sufficiently high, such as immediately after a cold start of the engine, it is preferable to operate the glow plug 42. In order to efficiently guide the fuel injected from the fuel supply nozzle 41 to the glow plug 42 and the oxidation catalyst 43, a collision member that collides and reflects the injected fuel may be provided.

  The engine 1 includes an electronic control unit (hereinafter referred to as ECU) 100 as control means. ECU 100 includes a CPU, a ROM, a RAM, an input / output port, a storage device, and the like. The ECU 100 controls the injector 7, the high pressure pump 5, the throttle valve 14, the fuel supply nozzle 41, the glow plug 42, and the like so that desired engine control is executed based on detection values of various sensors. The above-described air flow meter 12 is connected to the ECU 100 as sensors.

  The ECU 100 is connected to a crank angle sensor 15, an accelerator opening sensor 16, a common rail pressure sensor 25, an exhaust temperature sensor 35, and a water temperature sensor 36. The crank angle sensor 15 outputs a crank pulse signal to the ECU 100 when the crank angle rotates. ECU 100 detects the crank angle of engine 1 based on the crank pulse signal and calculates the rotational speed of engine 1. The accelerator opening sensor 16 outputs a signal corresponding to the accelerator pedal opening (accelerator opening) operated by the user to the ECU 100. The common rail pressure sensor 25 outputs a signal corresponding to the fuel pressure (common rail pressure) in the common rail 6 to the ECU 100.

  The exhaust temperature sensor 35 outputs a signal corresponding to the exhaust temperature at the outlet of the exhaust purification catalyst 34 to the ECU 100. The water temperature sensor 36 outputs a signal corresponding to the engine coolant temperature to the ECU 100.

  In particular, the ECU 100 can deactivate the # 2 and # 3 cylinders corresponding to the second exhaust passage 32 independently of the # 1 and # 4 cylinders corresponding to the first exhaust passage 31. That is, the ECU 100 stops the fuel injection by the # 7 and # 3 cylinder injectors 7 while executing the fuel injection by the # 1 and # 4 cylinder injectors 7 and deactivates the # 2 and # 3 cylinders. The engine can be operated only by the # 1 and # 4 cylinders.

  According to this embodiment, the # 2 and # 3 cylinders are deactivated, and the engine can be operated with only the # 1 and # 4 cylinders. If it carries out like this, # 2 and # 3 cylinder will function as an air pump which discharges intake air as it is. Then, the air discharged from the # 2 and # 3 cylinders is supplied to the burner device 40, and a gas having a sufficiently high oxygen concentration is supplied to the burner device 40. Accordingly, the burner device 40 can ignite the injected fuel well and reliably, and the burner device 40 can be operated efficiently.

  Here, it is assumed that the burner device 40 is installed on the downstream side of the turbine T in the first exhaust passage 31, and the # 1 and # 4 cylinders are idle cylinders. In this case, the air discharged from the # 1 and # 4 cylinders is heated by the turbine T when passing through the turbine T. Then, the oxygen concentration of the air will fall, and the burner apparatus 40 cannot be operated as efficiently as this embodiment.

  In this embodiment, the exhaust passage is divided into cylinders that can be deactivated (# 2, # 3 cylinders) and cylinders that are not (# 1, # 4 cylinders), and the former includes the burner device 40 and the latter includes the turbine T. I made it. Therefore, the air discharged from the restable cylinder can be supplied to the burner device 40 without passing through the turbine T, and the efficiency of the burner device 40 can be improved.

  In a normal turbo engine, that is, an engine in which a turbine is provided in an exhaust passage common to all cylinders, it is assumed that a burner device is provided on the downstream side of the turbine. In this case, if air is supplied to the burner device, it is limited at the time of fuel cut (fuel injection stop) of all the cylinders, and there is a possibility that the engine operating conditions when operating the burner device are limited. In the present embodiment, this is not the case, and only the partial cylinders can be fuel cut and the remaining cylinders can be operated. Therefore, it is considered that the burner device can be operated under all engine operating conditions. Naturally, the burner device can be operated even when the fuel is cut in all cylinders.

  The heated gas from the burner device 40 and the exhaust gas from the turbine T are merged at the merge position X and mixed. Thereby, it is possible to raise the temperature of the exhaust gas, which has become low temperature due to the heat received by the turbine T, by mixing with the heated gas. Such mixed gas heats the exhaust purification catalyst 34 to maintain and promote its warm-up and active state.

An example of the control executed by the ECU 100 when the burner device 40 is operated is shown in FIG. First, in step S101, it is determined whether or not the operating condition of the burner device 40 is satisfied. For example, when the exhaust temperature detected by the exhaust temperature sensor 35 is equal to or lower than a predetermined temperature corresponding to the upper limit temperature when the exhaust purification catalyst 34 is inactive, it is determined that the operating condition is satisfied, and otherwise, the operating condition is not satisfied. To be judged.
Alternatively, the activation or inactivation of the exhaust purification catalyst 34 may be determined by substituting the water temperature or the fuel injection amount. That is, when the water temperature detected by the water temperature sensor 36 is a predetermined temperature (for example, 60 ° C.) or less and the fuel injection amount from the injector 7 is a predetermined amount (for example, 30 m ³ / st) or less, the operation condition is established. If not, it may be determined that the operating condition is not satisfied.

  Thus, here, an example is shown in which the burner device 40 is operated before the exhaust purification catalyst activation immediately after the cold start. However, the timing for operating the burner device 40 is not limited to such an example.

  When the operating condition is not satisfied, the standby state is established. On the other hand, when the operating condition is satisfied, the process proceeds to step S102. In step S102, fuel injection to the # 2 and # 3 cylinders is stopped, and these cylinders are deactivated.

  Next, in step S103, the burner device 40 is activated. That is, the fuel supply nozzle 41 is energized to supply fuel from the fuel supply nozzle 41, and at the same time, the glow plug 42 is energized. As a result, heated gas is generated, and warming up of the exhaust purification catalyst 34 is promoted. In particular, the burner device 40 is supplied with air from the # 2 and # 3 cylinders, so that ignition in the burner device 40 can be ensured and the burner device 40 can be operated with high efficiency.

  As mentioned above, although embodiment of this invention was described, this invention can also take other embodiment. For example, the use, type, and the like of the internal combustion engine are arbitrary, and are not limited to the compression ignition type internal combustion engine, but may be a spark ignition type internal combustion engine (gasoline engine). The number of cylinders that can be deactivated is arbitrary, and is not limited to two cylinders as described above, but may be one cylinder or three or more cylinders.

  The embodiment of the present invention is not limited to the above-described embodiment, and includes all modifications, applications, and equivalents included in the concept of the present invention defined by the claims. Therefore, the present invention should not be construed as being limited, and can be applied to any other technique belonging to the scope of the idea of the present invention.

1 internal combustion engine 8 turbocharger 31 first exhaust passage 32 second exhaust passage 33 collecting passage 34 exhaust purification catalyst 40 burner device 41 fuel supply nozzle 42 glow plug 43 oxidation catalyst T turbine

Claims (3)

A first exhaust passage is connected to some cylinders of the multi-cylinder internal combustion engine, a second exhaust passage is connected to the remaining cylinders of the internal combustion engine, and the first and second exhaust passages are connected to the downstream end. To gather together to form a gathering passage,
A turbocharger turbine is disposed in the first exhaust passage;
The rest of the cylinders can be stopped independently of the some cylinders by stopping fuel injection,
An internal combustion engine characterized in that a burner device having a fuel supply nozzle, a glow plug and an oxidation catalyst is disposed in the second exhaust passage.   The internal combustion engine according to claim 1, wherein the burner device is operated when the remaining cylinders are deactivated.   The internal combustion engine according to claim 1, wherein an exhaust purification catalyst is disposed in the collecting passage.

Images