JP3557931B2 - Internal combustion engine having a combustion heater - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an internal combustion engine having a combustion type heater, and more particularly to an internal combustion engine having a combustion type heater for introducing combustion gas into an intake system of the internal combustion engine in order to increase the temperature of engine-related components of the internal combustion engine.
[0002]
2. Description of the Related Art
2. Description of the Related Art In an internal combustion engine, particularly a diesel engine, exhaust gas discharged from the engine contains a large amount of PM (Particulate Matter) such as soot and SOF (Soluble Organic Fraction). Therefore, conventionally, a filter called DPF (Diesel Particulate Filter) is provided in the exhaust passage, and PM is collected by this.
[0003]
Since this filter gradually clogs by trapping PM, the exhaust resistance increases and the engine load increases. Therefore, it is necessary to desorb the trapped PM from the filter at an appropriate timing (hereinafter, desorption of PM from the filter is referred to as “regeneration of the filter”, and PM desorption processing is referred to as “filter regeneration”. Playback process).
[0004]
To regenerate the filter, PM should be burned, soot and SOF become CO2₂And H₂Since it changes to O, not only can the filter be regenerated, but also PM can be rendered harmless and released to the atmosphere.
[0005]
However, combustion of soot requires a temperature of 600 ° C. or higher. If the combustion temperature of soot is to be obtained by the heat of the exhaust gas flowing through the filter, the exhaust gas temperature is high during high-load operation of the engine. However, this was not possible during low load or medium load operation because the exhaust gas temperature was low. In general, the engine is operated at a lower load / medium load more often than at a high load (time), and as a result, the state of insufficient regeneration of the filter tends to become chronic, which causes a problem. Met.
[0006]
On the other hand, some vehicles are equipped with a combustion type heater for heating the passenger compartment separately from the internal combustion engine as a power source. For example, in Japanese Patent Application Laid-Open No. 60-78819, an air passage is provided around the combustion chamber of a combustion type heater, through which air for heating the vehicle interior flows, and the heat of the combustion gas of the combustion type heater is used to heat the vehicle interior. The air for heating the cabin is heated and blown out into the cabin through an air conditioner to be used for heating the cabin, while the combustion gas discharged from the combustion type heater is supplied to the exhaust system of the internal combustion engine. There is disclosed a technique in which the combustion gas is introduced upstream of a catalytic converter, and the combustion gas of the combustion heater is purified by the catalytic converter together with the exhaust gas of the internal combustion engine and released to the atmosphere.
[0007]
In the technology disclosed in this publication, the combustion gas of the combustion heater is introduced into the exhaust system of the internal combustion engine, but this is only for purifying the combustion gas by the catalytic converter. Further, this publication does not disclose a filter (DPF), nor does it disclose conditions for introducing a combustion gas upstream of a catalytic converter.
[0008]
The present invention has been made in view of such problems of the conventional technology, and an object of the present invention is to solve the problem of the combustion type heater when the exhaust gas temperature is lower than the temperature required for filter regeneration. The temperature is increased by introducing the combustion gas into the exhaust system, and the nitrogen monoxide (NO) in the gas is converted into nitrogen dioxide (NO) by the oxidation catalyst.₂) To act as an oxidant for carbon at relatively low temperatures₂And promote regeneration of the filter.
[0009]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems. An internal combustion engine having a combustion heater according to the present invention includes a filter provided in an exhaust system of the internal combustion engine for purifying exhaust gas of the internal combustion engine, and a first filter provided upstream of the filter in the exhaust system of the internal combustion engine. An oxidation catalyst, a combustion gas exhaust passage for introducing combustion gas of a combustion type heater provided to raise an engine-related element of the internal combustion engine into an intake system of the internal combustion engine, and a combustion gas discharge path of the combustion type heater.Including NOA combustion gas bypass passage that bypasses a cylinder of the internal combustion engine and introduces the combustion gas upstream of the first oxidation catalyst in an exhaust system of the internal combustion engine; and a combustion gas of the combustion heater when regenerating the filter. And an introduction means for introducing the gas into the combustion gas bypass passage.
[0010]
When the exhaust gas of the internal combustion engine is supplied to the filter, PM (Particulate Matter) such as SOF (Solutable Organic Fraction) and soot in the exhaust gas is collected by the filter, so that the filter is gradually clogged. . Therefore, it is necessary to burn and remove PM trapped in the filter at an appropriate timing, that is, to regenerate the filter. However, burning PM requires a considerably high temperature (about 600 ° C. or more). In order to obtain this temperature with the exhaust gas of the internal combustion engine, the internal combustion engine must be operated at a considerably high output. In particular, in the case of an internal combustion engine for driving a vehicle, under normal operating conditions, it is possible to obtain the exhaust gas temperature required for regeneration of the filter only during high-load operation, and the low- and medium-load operation is frequently performed. Sometimes the exhaust gas temperature is not enough to regenerate the filter.
[0011]
However, in the internal combustion engine of the present invention, when the filter is regenerated, the combustion gas of the combustion heater is introduced into the combustion gas bypass passage by the introduction means, and is introduced into the exhaust system upstream of the filter through the combustion gas bypass passage. The gas and combustion gas flow into the filter as a mixed gas. The temperature of the combustion gas of the combustion type heater is considerably high, and the temperature of the mixed gas becomes higher than the exhaust gas temperature, so that the temperature required for regeneration of the filter can be obtained. In addition, since the first oxidation catalyst is provided upstream of the filter, nitrogen monoxide (NO) in the mixed gas is oxidized by the first oxidation catalyst to form nitrogen dioxide (NO).₂). NO₂Acts as an oxidizing agent at temperatures above about 250 ° C., thus promoting filter regeneration.
[0012]
In the present invention, the internal combustion engine can be exemplified by a gasoline engine or a diesel engine, and can be exemplified by a direct injection lean burn gasoline engine or a diesel engine. Further, in the present invention, the filter for purifying the exhaust gas may be a DPF (Diesel Particulate Filter), but is not limited thereto.
[0013]
In the present invention, the engine-related element of the internal combustion engine heated by the combustion heater is engine cooling water or the internal combustion engine itself. The combustion type heater independently burns fuel and discharges combustion gas without being affected by combustion in the cylinder of the internal combustion engine body.
[0014]
In the present invention, the introduction means is for introducing the combustion gas of the combustion type heater into the combustion gas bypass passage or for preventing the introduction thereof, and may be constituted by a valve device. The operation of the introduction means is controlled by a CPU (Central Processing Unit) of an ECU (Engine Control Unit).
[0015]
Regarding the filter regeneration timing, the filter regeneration may be performed during the entire period during which the internal combustion engine is operating, or the filter regeneration timing may be set when the filter clogging reaches a predetermined level. . Here, the determination as to whether or not the clogging of the filter has reached a predetermined degree may be made based on whether or not the integrated operation time of the internal combustion engine has reached a predetermined time, or may be determined by the internal combustion engine for driving a vehicle. If so, the determination may be made based on whether the accumulated traveling distance has reached a predetermined value, or may be determined based on whether the pressure loss of the filter has reached a predetermined value.
[0016]
Further, in the present invention, when the inlet temperature of the first oxidation catalyst is equal to or lower than a predetermined temperature, the introducing means may introduce the combustion gas of the combustion heater into the combustion gas bypass passage. it can. With this configuration, when the inlet temperature of the first oxidation catalyst exceeds the predetermined temperature, the high-temperature combustion gas does not flow into the first oxidation catalyst, so that the durability of the first oxidation catalyst is improved.
[0017]
The “predetermined temperature” in “when the inlet temperature of the first oxidation catalyst is equal to or lower than a predetermined temperature” may be a temperature at which carbon is burned in an oxygen-excess atmosphere, or if carbon is NO.₂May be the temperature at which combustion takes place in the presence of.
[0018]
In the present invention, when the combustion gas of the combustion heater is introduced into the combustion gas bypass passage by the introduction means, combustion of the combustion heater is performed so that NOx is generated by combustion in the combustion heater. It is preferable to control. With this configuration, NOx generated by the combustion heater can also be used for regeneration of the filter, thereby promoting regeneration of the filter. Here, the combustion of the combustion type heater is controlled by controlling the air-fuel ratio of the combustion type heater. The air-fuel ratio control of the combustion type heater should be executed by controlling the supply amount of combustion fuel of the combustion type heater, controlling the supply amount of combustion air of the combustion type heater, or controlling both. Can be. This air-fuel ratio control is executed by the CPU of the ECU.
[0019]
In the present invention, a NOx sensor for detecting a NOx concentration is provided upstream of the first oxidation catalyst and downstream of a connection point between the exhaust system of the internal combustion engine and the combustion gas bypass passage, and the NOx sensor detects the NOx concentration. The air-fuel ratio of the combustion heater can be controlled based on the NOx concentration. There is a correlation between the air-fuel ratio of the combustion heater and the combustion temperature of the combustion heater, and the combustion temperature of the combustion heater determines the concentration of NOx generated by the combustion heater. Therefore, when the air-fuel ratio of the combustion heater is controlled based on the NOx concentration detected by the NOx sensor, the NOx concentration of the mixed gas flowing into the first oxidation catalyst is controlled to an optimum concentration for regeneration of the filter. Can be.
[0020]
In the present invention, it is possible to provide a second oxidation catalyst in the combustion gas bypass passage. This is particularly effective when the introduction means introduces the combustion gas of the combustion type heater into the combustion gas bypass passage when the inlet temperature of the first oxidation catalyst is equal to or lower than a predetermined temperature. is there. With this configuration, when the inlet temperature of the first oxidation catalyst is equal to or higher than the predetermined temperature, high-temperature combustion gas from the combustion heater does not flow through the second oxidation catalyst, and high-temperature deterioration of the second oxidation catalyst is suppressed. Is done.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of an internal combustion engine having a combustion heater according to the present invention will be described with reference to the drawings of FIGS.
[0022]
[First Embodiment]
First, a configuration of an internal combustion engine having a combustion heater according to the first embodiment will be described with reference to FIG. An engine 1 for driving a vehicle as an internal combustion engine is a water-cooled diesel engine, and includes an engine body 3 having a water jacket containing engine cooling water, and air necessary for combustion in a plurality of cylinders (not shown) of the engine body 3. An exhaust device 7 for discharging exhaust gas after combustion of the air-fuel mixture into the atmosphere, and a cabin heater 9 for heating the interior of a vehicle on which the engine 1 is mounted.
[0023]
The intake device 5 starts with an air cleaner 13 that takes in fresh air into a cylinder and terminates an intake port (not shown) of the engine body 3. In the meantime, a compressor 15a of the turbocharger 15, which is a supercharger, an intercooler 19, and an intake manifold 21 for distributing air coming through the intercooler 19 to the respective cylinders are provided.
[0024]
The components of the intake device 5 are connected by a plurality of connecting pipes described below that belong to the intake pipe 23.
The intake pipe 23 composed of a plurality of connection pipes is connected to the downstream connection pipe 27 which is in a pressurized state by forcibly pushing the intake air coming into the intake device 5 from the air cleaner 13 and the upstream which is not so with the compressor 15a as a boundary. It can be roughly divided into the side connection pipe 25.
[0025]
The upstream connecting pipe 25 connects the air cleaner 13 and the compressor 15 a with a main pipe 29 linearly extending in the left-right direction in FIG. 1 and a branch for heater as a branch pipe connected to the main pipe 29 in a bypass shape. And a tube 31.
[0026]
The downstream connection pipe 27 is an L-shaped connection pipe extending in the vertical direction in FIG. 1 that connects the compressor 15a and the intake manifold 21.
The heater branch pipe 31 includes a combustion type heater 17 in the middle thereof, and connects an upstream end of the combustion type heater 17 with the main pipe 29 and supplies air to the combustion type heater 17. A downstream end of the heater 17 and the main pipe 29 are connected to each other, and a combustion gas discharge path 35 for discharging combustion gas from the combustion heater 17 to the main pipe 29 is provided. In each of the connection points C1 and C2 between the air supply path 33 and the combustion gas discharge path 35 and the main pipe 29, the connection point C1 is located on the upstream side of the main pipe 29 than the connection point C2.
[0027]
A valve device 44 is provided in the air supply passage 33 connecting the upstream end of the combustion heater 17 and the main pipe 29 near the combustion heater 17. As shown in FIG. 4, the valve device 44 is installed between a valve body 44a that opens and closes the air supply passage 33, a drive motor 44b that drives the valve body 44a to open and close, and the drive motor 44b and the valve body 44a. An open / close mechanism 44c is provided, and the operation of the drive motor 44b is controlled by a CPU (not shown) of an engine control control unit (ECU) 46 (see FIG. 1). Further, the valve device 44 is also activated when the main throttle pipe 70 is throttled by an intake throttle valve 70 to close the valve body 44a in order to actively stop the driving of the engine 1.
[0028]
A combustion gas cooler 84 for cooling the combustion gas of the combustion heater 17 is provided in the combustion gas discharge passage 35.
A portion of the combustion gas discharge passage 35 connecting the downstream end of the combustion heater 17 and the combustion gas cooler 84 and the downstream connection pipe 27 are connected by a branch pipe 95. A three-way valve 97 having three ports is provided at a portion connecting the combustion gas discharge path 35 and the branch pipe 95. The three-way valve 97 is configured as shown in FIG.
[0029]
The three-way valve 97 connects a first port 97a, which is one of the three ports, to a downstream end of the combustion heater 17 (an exhaust outlet 17d described later).₂), The second port 97b, one of the remaining two ports, is connected to the combustion gas cooler 84 side of the combustion gas discharge path 35, and the third port 97c, the remaining one port, is connected to the branch pipe 95. Connect with In the case body 97d of the three-way valve 97, a valve body 98 which is moved in the longitudinal direction of the case body 97d by the operation of a diaphragm (not shown) is provided. The valve body 98 connects two of the three ports, that is, the first port 97a and the second port 97b, or the first port, depending on the position where the valve body 98 moves in the case body 97d. 97a and the third port 97c. In this case, when the first port 97a and the second port 97b are in communication, the third port 97c is closed, and when the first port 97a and the third port 97c are in communication, the second port 97c is closed. Port 97b closes. The operation of the diaphragm of the three-way valve 97 is controlled by the CPU of the ECU 46, that is, the connection state of each port of the three-way valve 97 is controlled by the ECU 46.
[0030]
The intake air passing through the main pipe 29 is divided into intake air that branches to the air supply path 33 at the connection point C1 and intake air that flows downstream without branching. When the three-way valve 97 is controlled so as to communicate the first port 97a and the second port 97b, the intake air branched into the air supply path 33 is supplied from the air supply path 33 to the combustion heater 17 to combustion. The gas returns to the main pipe 29 at the connection point C2 via the gas discharge path 35, and merges with the unbranched intake air. As a result, the temperature of the intake air entering the engine body 3 is increased. Further, when the three-way valve 97 is controlled so as to communicate the first port 97a and the third port 97c, the intake air branched into the air supply passage 33 enters the air supply passage 33 → the combustion heater 17 → branch. It flows through the pipe 95 and does not return to the main pipe 29.
[0031]
On the other hand, an intercooler 19 and an intake throttle valve 70 are provided in the middle of the downstream connection pipe 27 at a position upstream of a connection point with the branch pipe 95. The intercooler 19 is located upstream of the intake throttle valve 70.
[0032]
The intercooler 19 cools air downstream of the installation location of the compressor 15a, which is received by the combustion heater 17 and the compressor 15a, which warms the intake air for promoting warm-up of the engine 1 and improving startability.
[0033]
The operation of the intake throttle valve 70 is controlled by the CPU of the ECU 46 according to the operating state of the engine 1. In addition, when the engine 1 is stopped positively, the intake throttle valve 70 is controlled to be fully closed.
[0034]
The exhaust device 7 is provided with an exhaust manifold 37 and a turbine 15b of the turbocharger 15 on an exhaust pipe 42 from an exhaust port (not shown) of the engine main body 3 as a start end to an exhaust purification device 50 at the end. The exhaust gas purification device 50 accommodates an oxidation catalyst (first oxidation catalyst) 52 in an upstream part in a casing 51 and accommodates a DPF (Diesel Particulate Filter) 53 as a filter in a downstream part in the casing 51. .
[0035]
The DPF 53 has a large number of elongated cells partitioned by a porous thin wall, and a cell having an upstream opening and a downstream closing and a cell having a downstream opening and closing the upstream are arranged adjacent to each other. The exhaust gas flows through the thin-walled wall from the cell with the upstream side opened to the cell with the downstream side opened, and at that time, the soot and the SOF (Soluble Organic Fraction) in the exhaust gas. The structure is such that PM (Particulate Matter) is collected on a thin wall.
[0036]
The exhaust pipe 42 includes an inlet gas temperature sensor 40 and a NOx sensor 41 near the inlet of the exhaust gas purification device 50. The incoming gas temperature sensor 40 outputs an electric signal proportional to the temperature of the gas flowing into the exhaust gas purification device 50 to the ECU 46, and the NOx sensor 41 outputs an electric signal proportional to the NOx concentration contained in the gas flowing into the exhaust gas purification device 50. Output to ECU46.
[0037]
The engine body 3 is provided with an EGR device 88 as an exhaust gas recirculation device that returns a part of the exhaust gas to the intake system. The EGR device 88 includes an EGR passage 90 that connects the exhaust manifold 37 of the exhaust pipe 42 and the intake manifold 21 of the intake pipe 23 by bypassing a cylinder (not shown) of the engine body 3.
[0038]
The EGR passage 90 is provided with an EGR valve 92 for controlling the amount of EGR gas passing therethrough. The EGR valve 92 is electrically connected to the CPU of the ECU 46, and basically opens when the engine 1 is sufficiently warmed up, in which the EGR device 88 functions as an original exhaust gas recirculation device. It is a variable controllable valve. Further, the EGR valve 92 is connected to a pressure control valve (not shown) for negatively controlling the EGR valve 92, such as a duty VSV. When a drive pulse signal having a duty ratio corresponding to the ratio of the fully open time and the fully closed time of the EGR valve 92, in other words, a duty ratio corresponding to the open ratio of the EGR valve 92, is input from the CPU, the pressure control valve The EGR valve 92 is driven according to the following.
[0039]
Further, the branch pipe 95 of the intake device 5 and a portion of the exhaust pipe 42 immediately upstream of the exhaust gas purification device 50 are a combustion gas bypass pipe (a combustion gas bypass passage, hereinafter simply referred to as a bypass pipe) that bypasses the engine body 3. ) 48. The connection point C3 between the exhaust pipe 42 and the bypass pipe 48 is located on the upstream side of the exhaust pipe 42 with respect to the inlet gas temperature sensor 40 and the NOx sensor 41.
[0040]
A portion connecting the branch pipe 95 and the bypass pipe 48 is provided with a three-way valve 97 'having three ports. The configuration of the three-way valve 97 'is the same as the configuration of the three-way valve 97 described above, except for the connection destination of the three ports. Therefore, the description of the configuration of the three-way valve 97 'is omitted, and only the connection destination of the three ports and the communication state of the ports depending on the position of the valve body 98 will be described below with reference to FIG.
[0041]
The three-way valve 97 'connects the first port 97a, one of the three ports, to the three-way valve 97 side of the branch pipe 95, and branches the second port 97b, one of the remaining two ports. The third port 97 c, which is one remaining port, is connected to the bypass pipe 48. When the valve body 98 of the three-way valve 97 'communicates the first port 97a and the second port 97b and closes the third port 97c, the combustion gas of the combustion heater 17 introduced into the branch pipe 95 through the three-way valve 97 Flows through the downstream connecting pipe 27 to the intake manifold 21 and does not flow into the bypass pipe 48. On the other hand, when the valve body 98 of the three-way valve 97 ′ communicates the first port 97 a and the third port 97 c and closes the second port 97 b, the combustion type heater 17 introduced into the branch pipe 95 through the three-way valve 97 is closed. The combustion gas flows to the bypass pipe 48 and does not flow to the downstream connection pipe 27. The operation of the three-way valve 97 'is also controlled by the CPU of the ECU 46.
[0042]
The combustion heater 17 is a combustion device provided separately from the engine body 3 and attached to the engine 1, and independently burns without being affected by combustion in a cylinder (not shown) of the engine body 3. To emit combustion gas.
[0043]
The operation of the combustion heater 17 is controlled by the CPU so as to operate when the engine 1 is in a predetermined operating state. “When the engine 1 is in a predetermined operating state” means that the engine 1 is operating or the engine 1 is operating in a cold state at a temperature of about −10 ° C. to 15 ° C. or in an extremely cold state at a temperature of −10 ° C. or less. Is started, when the calorific value of the engine 1 itself is small (for example, when fuel consumption is small), and when the calorific value of the engine 1 itself is small and the amount of heat received by the cooling water is small, and further higher than 15 ° C. The time when the cooling water temperature is low immediately after starting at room temperature, and the time when the engine 1 is under such conditions is the time when the combustion heater 17 needs to be operated. It is the CPU of the ECU 46 that determines when it is necessary to operate the combustion heater 17, and when the CPU determines that it is necessary to operate the combustion heater 17, the combustion heater 17 is activated. High-temperature combustion gas is emitted therefrom, and the combustion gas is used for warming up the engine.
[0044]
The combustion heater 17 is a device that raises the temperature of an engine-related element such as engine cooling water in order to heat the vehicle interior or warm up the engine. However, in the present invention, the combustion heater 17 is used to regenerate the DPF 53 in the exhaust gas purification device 50. Also function as a device for promoting its regeneration. Therefore, the operation of the combustion heater 17 is controlled by the CPU of the ECU 46 so that the combustion heater 17 is also operated when the CPU of the ECU 46 determines that the combustion heater 17 needs to be operated to regenerate the DPF 53. You. This will be described later in detail.
[0045]
Next, the structure of the combustion heater 17 will be described with reference to FIG. The combustion heater 17 is connected to the water jacket containing engine cooling water. Therefore, the combustion type heater 17 includes a cooling water passage 17a through which the engine cooling water passes. The cooling water passage 17a is heated by the combustion gas flowing through the combustion chamber 17d, which is a heat source.
[0046]
The combustion chamber 17d has a combustion cylinder 17b disposed therein, and the combustion cylinder 17b is covered with a cylindrical partition wall 17c. By covering the combustion cylinder 17b with the partition 17c, the combustion chamber 17d is defined in the case body 43d of the combustion chamber main body 43, and the cooling water passage 17a is formed between the inner surface of the case body 43d and the outer surface of the partition 17c. I do.
[0047]
The combustion chamber 17d also functions as an air passage in the heater. Therefore, the combustion chamber 17d is connected to the air supply passage 33 and the combustion gas discharge passage 35 of the combustion type heater 17 through the air supply port 17d.₁And exhaust outlet 17d₂Connected. Then, as described above, when the intake air branches from the main flow pipe 29 and passes through the air supply path 33, as shown by a solid line arrow in FIG. 4, the intake air passes through the air supply path 33 → the combustion chamber 17d → the combustion gas discharge path 35. Then, the intake air containing the combustion gas returns to the main pipe 29. Since the intake air is heated by the combustion heat of the combustion gas, the heated intake air is exhausted from the combustion chamber main body 43 until the heated intake air is discharged from the combustion chamber main body 43 via the path indicated by the solid arrow. The cooling water flowing through the cooling water passage 17a as a heat medium is warmed. Therefore, the combustion chamber 17d can be said to be a heat exchange passage.
[0048]
A fuel pump 47 is connected to the combustion cylinder 17b via a fuel supply pipe 17e as a fuel supply path, and the fuel for combustion is supplied to the combustion cylinder 17b by the pump pressure of the fuel pump 47. . The operation of the fuel pump 47 is controlled by the CPU of the ECU 46 to vary the pump pressure and control the amount of combustion fuel supplied. When fuel for combustion is supplied to the combustion chamber 17d, this fuel is vaporized in the combustion cylinder 17b. Then, the vaporized fuel is ignited by an ignition device (not shown), and the vaporized fuel burns.
[0049]
Further, the combustion chamber main body 43 is provided with a blower fan 45 for feeding intake air coming from the air supply passage 33 into the combustion cylinder 17b, and a flame F is generated by supplying air to the combustion cylinder 17b. The operation of the blower fan 45 is controlled by the CPU of the ECU 46 to vary the output, and the output adjustment changes the amount of air flowing through the combustion chamber 17d. Therefore, the amount of air flowing in the combustion chamber 17d can be controlled by adjusting the output of the blower fan 45.
[0050]
The combustion type heater 17 controls the air-fuel ratio (A / F) by the CPU of the ECU 46 controlling the fuel pump 47 and the blower fan 45 to control the supply amount and the air amount of the fuel for combustion. The state is controlled, and the output of the combustion heater 17 is controlled. Therefore, in this embodiment, the blower fan 45, the fuel pump 47, and the ECU 46 constitute a combustion-type heater air-fuel ratio control unit.
[0051]
On the other hand, the cooling water passage 17a has a cooling water inlet 17a.₁And cooling water outlet 17a₂And a cooling water inlet 17a₁As shown in FIG. 1, is connected to a cooling water discharge port of a water jacket (not shown) of the engine body 3 through a water pipe W1.
[0052]
Also, the cooling water outlet 17a₂Is connected to the vehicle interior heater 9 via a water pipe W2. The cabin heater 9 is connected to a cooling water inlet of the water jacket of the engine body 3 via a water pipe W3.
[0053]
Therefore, the cooling water of the water jacket reaches the combustion heater 17 via the water pipe W1 and is warmed there, and thereafter, from the combustion heater 17 to the vehicle heater 9 via the water pipe W2, the cooling water for the vehicle cabin. Heat is exchanged as a heat medium of the heater 9 to emit warm air into the vehicle interior. The cooling water whose temperature has been lowered by the heat exchange returns to the water jacket via the water pipe W3. In this manner, the cooling water circulates between the engine main body 3, the combustion type heater 17, and the vehicle interior heater 9 via the water pipes W1 to W3.
[0054]
The air supply passage 33 and the combustion gas discharge passage 35 are tributary pipes of the main flow pipe 29 belonging to the intake pipe 23. Can be considered as a component of the combustion heater 17.
[0055]
Next, the operation of this embodiment will be described. PM (such as soot and SOF) in the exhaust gas discharged from each cylinder of the diesel engine 1 is collected by the DPF 53 of the exhaust purification device 50. First, the flow of air at that time will be described.
[0056]
The air flow is slightly different when engine warm-up is required and when it is not. The above-mentioned “when the engine 1 is in the predetermined operating state” is when the engine needs to be warmed up. At this time, the ECU 46 operates the combustion type heater 17 and sets the combustion type heater 17 to a predetermined lean empty state. Operating at the fuel ratio, the intake throttle valve 70 is fully opened, the EGR valve 92 is fully closed, the valve body 44a of the valve device 44 is fully opened, and the first port 97a and the second port 97b of the three-way valve 97 communicate with the third port 97c. Is closed, the first port 97a and the third port 97c of the three-way valve 97 'are communicated, and the second port 97b is closed. When the open / close state of each valve is as described above, the air that has entered the intake device 5 from the air cleaner 13 through the following path reaches the exhaust device 7.
[0057]
{Circle around (1)} The air that has entered the main pipe 29 of the intake pipe 23 from the air cleaner 13 branches into air that flows through the air supply path 33 of the branch pipe 31 for heater and air that flows through the main pipe 29 as it is downstream.
[0058]
(2) The air that has entered the air supply passage 33 passes through the valve device 44 and is then sent into the combustion chamber main body 43 of the combustion heater 17.
(3) The air that has entered the combustion chamber main body 43 is provided as combustion air for combustion fuel sent from the fuel supply pipe 17e in the combustion chamber 17d of the combustion chamber main body 43, and after combustion, becomes combustion gas and becomes combustion gas. Exit to the discharge path 35.
[0059]
(4) The high-temperature combustion gas that has exited the combustion gas discharge passage 35 enters the main flow tube 29 from the connection point C2 of the main flow tube 29 via the three-way valve 97 and the exhaust gas cooler 84, and passes through the main flow tube 29 without branching. Merges with the flowing air to increase the temperature of the intake air.
[0060]
(5) The intake air whose temperature has been increased passes through the compressor 15a of the turbocharger 15 and the intercooler 19, passes through the intake throttle valve 70, enters the intake manifold 21, enters each cylinder of the engine body 3, and enters the cylinder. Is provided as combustion air.
[0061]
{Circle around (6)} After the fuel is burned in each cylinder, the fuel becomes exhaust gas to reach the exhaust manifold 37, and is further exhausted through the exhaust pipe 42, the turbine 15b of the turbocharger 15, and the exhaust purification device 50.
[0062]
As described above, since the hot combustion gas of the combustion heater 17 enters the cylinder of the engine body 3, the warm-up of the engine 1 proceeds.
Since the third port 97c of the three-way valve 97 is closed, the combustion gas of the combustion heater 17 does not flow out of the three-way valve 97 to the branch pipe 95, and the second port of another three-way valve 97 '. Since the 97 b is closed, the air flowing through the downstream connecting pipe 27 does not flow out to the bypass pipe 48. Thus, the combustion gas emitted from the combustion heater 17 can be effectively used for warming up the engine.
[0063]
Then, when the engine 1 is sufficiently warmed up, the EGR valve 92 is opened, and the valve body 44a of the valve device 44 is closed. This is because the exhaust gas recirculation of the EGR device 88 is executed because the warm-up of the engine 1 is sufficient, and the valve body 44a is opened and the combustion type heater 17 is opened even though the warm-up of the engine 1 is sufficient. This is because it is not necessary to send the hot combustion gas to the engine body 3.
[0064]
Note that there is no compressor 15a in a portion between the connection point C1 with the air supply passage 33 and the connection point C2 with the combustion gas discharge passage 35 in the main pipe 29, and the compressor 15a does not operate in this portion. Since the pressure at the location C2 does not become higher than the pressure at the connection location C1, and the air is blown through the air supply path 33 by the blower fan 45 of the combustion heater 17, the air supply path 33 and the combustion gas Backflow does not occur in the combustion chamber 17d of the combustion type heater 17 connected to the main pipe 29 via the discharge path 35. Therefore, there is no occurrence of a flashback phenomenon in which the direction of the flame of the combustion heater 17 is directed toward the air supply passage 33.
[0065]
As described above, the intake path is slightly different between when the engine 1 needs to be warmed up and when it is not necessary. In any case, the exhaust gas discharged from each cylinder of the engine body 3 passes through the exhaust gas purification device 50. At this time, PM in the exhaust gas is collected by the DPF 53, and the clean exhaust gas from which the PM has been removed is exhausted.
[0066]
In addition, in the engine 1, in parallel with the collection of the PM by the DPF 53, a regeneration process for removing the PM from the DPF 53 is performed to prevent the DPF 53 from being clogged. The regeneration process of the DPF 53 will be described below.
[0067]
The mechanism of the regeneration of the DPF 53 differs slightly depending on the temperature of the exhaust gas flowing out of each cylinder of the engine body 3, and will be described in the following three exhaust gas temperature ranges. FIG. 5 shows an operating state of the engine 1 (engine rotation) when the engine 1 does not need to be warmed up (normal temperature) and the combustion gas of the combustion heater 17 is not introduced into the intake pipe 23. FIG. 3 is an example of a temperature distribution diagram showing a relationship between exhaust gas temperature and speed (load). The broken line in the figure shows an example of road running resistance (road load) in the vehicle running state. In this example, when the vehicle speed is 40 km / Hr, the exhaust gas temperature becomes 250 ° C, and the vehicle speed becomes 140 km / Hr. Sometimes the exhaust gas temperature reaches 600 ° C.
[0068]
<High temperature range H>
In FIG. 5, a high temperature region H is a region where the exhaust gas temperature is 600 ° C. or higher. Soot can be burned in an oxygen-excess atmosphere at about 600 ° C. or more, and in the high temperature range H, the exhaust gas temperature is 600 ° C. or more. Therefore, when this exhaust gas flows through the DPF 53, the soot adhering to the DPF 53 Can be burned. Since the combustion temperature of SOF is lower than that of soot, in the high temperature region H, SOF attached to the DPF 53 can be burned at the same time. Therefore, in the high temperature range H, the PM trapped in the DPF 53 can be removed and the DPF 53 can be regenerated without taking any special measures. Therefore, the high temperature range H can be called a “natural DPF regeneration range”. In addition, SOF and soot burn to produce CO2₂And H₂Since it becomes O, the PM removed from the DPF 53 can be rendered harmless and discharged.
[0069]
However, since the high temperature range H corresponds to the high load operation of the engine 1, the operation frequency of the engine 1 is smaller than the operation frequency of other temperature ranges.
[0070]
<Medium temperature range M>
In FIG. 5, the middle temperature range M is a range where the exhaust gas temperature is 250 to 600 ° C. When the exhaust gas in the middle temperature range M is directly passed through the DPF 53, the temperature required for combustion of the SOF is 200 ° C. or higher, so that if the exhaust gas temperature is higher than that, the SOF can be burned. As described above, since the combustion of soot requires an exhaust gas temperature of about 600 ° C. or more, the soot cannot be burned. However, in the case of the exhaust purification device 50, since the oxidation catalyst 52 is provided on the upstream side of the DPF 53, by passing the exhaust gas in the medium temperature range M through the exhaust purification device 50, not only the SOF but also the DPF 53 Can be burned, and the DPF 53 can be regenerated. This is for the following reason.
[0071]
Nitrogen dioxide (NO₂) Is known to function as an oxidizing agent for carbon (C) at a temperature of about 250 ° C. or higher (see the following formula).
2NO₂+ C → 2NO + CO₂
That is, NO₂In the presence, carbon can be burned at temperatures above 250 ° C.
[0072]
By the way, the exhaust gas discharged from the diesel engine 1 contains NOx, and among the NOx in the exhaust gas, nitrogen monoxide (NO) is oxidized when passing through the oxidation catalyst 52 of the exhaust purification device 50. NO₂(See the following equation), and NO originally contained as the NOx component in the exhaust gas₂At the same time, it flows to the DPF 53.
NO + (1/2) O₂→ NO₂
[0073]
Therefore, in this engine 1, if the exhaust gas temperature is in the middle temperature range M where the exhaust gas temperature is 250 ° C. or higher, NO₂When the exhaust gas containing the gas flows into the DPF 53, the SOF and PM of the soot trapped in the DPF 53 can be burned, and the DPF 53 can be regenerated. Therefore, this medium temperature range M is "NO₂DPF continuous regeneration area ".
[0074]
However, the NOx concentration and the exhaust gas amount in the exhaust gas are determined according to the operating state of the engine 1, and the NOx concentration and the exhaust gas amount required to burn all of the PM trapped in the DPF 53. Is not always the case. Therefore, it is difficult to completely regenerate the DPF 53 only by operating the engine 1 in the middle temperature range M. Therefore, in the engine 1, measures are taken to execute the regeneration process of the DPF 53 even in the low temperature range L where the exhaust gas temperature is less than 250 ° C. Hereinafter, the regeneration process of the DPF 53 in the low temperature range L will be described.
[0075]
<Low temperature range L>
If the exhaust gas temperature is equal to or lower than 250 ° C., first, EGR control (drive duty ratio increase control of the EGR valve 92) is performed so as to increase the EGR gas amount, thereby increasing the exhaust gas temperature.
[0076]
If the exhaust gas temperature cannot be increased to 250 ° C. or more even by the EGR control, the combustion type heater 17 is operated to introduce the combustion gas to the upstream of the exhaust gas purification device 50 and mix with the exhaust gas to reduce the gas. Increase the temperature. At this time, by controlling the combustion in the combustion chamber 17d of the combustion heater 17 (controlling the air-fuel ratio of the combustion heater 17), nitrogen monoxide (NO) is actively generated in the combustion chamber 17d, and NOx concentration is increased. Then, NOx contained in the combustion gas is also introduced into the exhaust gas purification device 50 together with NOx in the exhaust gas, and is used for regeneration of the DPF 53. Therefore, regeneration of the DPF 53 by the same regeneration mechanism as in the middle temperature range M is further promoted. be able to.
[0077]
Next, a routine for executing the DPF regeneration process in the low temperature range L will be described with reference to FIG. A flowchart including a plurality of steps constituting this routine is stored in the ROM of the ECU 46, and all the processes in each step are executed by the CPU of the ECU 46.
[0078]
First, in step 101, the ECU 46 reads the incoming gas temperature detected by the incoming gas temperature sensor 40 as the DPF inlet temperature Tf, and determines whether or not the DPF inlet temperature Tf is lower than 250 ° C.
[0079]
If a negative determination is made in step 101, the process returns because the exhaust gas temperature is in the middle temperature region M or the high temperature region H, and the DPF 53 can be regenerated without raising the exhaust gas temperature.
[0080]
If an affirmative determination is made in step 101, the exhaust gas temperature is in the low temperature range L, and it is impossible to regenerate the DPF 53 unless the exhaust gas temperature is raised. Execute.
[0081]
In step 102, the ECU 46 executes EGR control so as to increase the EGR amount (that is, executes drive duty ratio increase control of the EGR valve 92), and adjusts the exhaust gas temperature discharged from each cylinder of the engine body 3. Enhance. When the combustion temperature is increased by increasing the EGR amount, the NO generation amount also increases, and the NOx for DPF regeneration also increases.
[0082]
However, if the EGR amount is extremely increased, smoke is generated and the amount of PM generated is increased. Therefore, the amount of PM in the exhaust gas at the inlet of the exhaust gas purification device 50 is not increased. , The EGR amount increase control is executed.
[0083]
Next, the ECU 46 proceeds from step 102 to step 103, reads the incoming gas temperature detected by the incoming gas temperature sensor 40 as the DPF inlet temperature Tf, and determines whether or not the DPF inlet temperature Tf is lower than 250 ° C. I do.
[0084]
If a negative determination is made in step 103, the process returns. This negative determination means that the exhaust gas temperature has become equal to or higher than 250 ° C. by the EGR amount increase control, and returns because there is no need to introduce the combustion gas from the combustion heater 17. However, since the exhaust gas temperature raising process by the EGR amount increase control is performed while suppressing the amount of generated PM to a predetermined amount or less, the EGR amount increase depends on the exhaust gas temperature before the EGR amount increase control is performed. It is difficult to raise the temperature of the exhaust gas discharged from each cylinder of the engine body 3 to 250 ° C. or more only by the increase control.
[0085]
If an affirmative determination is made in step 103, the process proceeds to step 104, where the combustion gas from the combustion heater 17 is introduced upstream of the exhaust gas purification device 50. That is, in step 104, the ECU 46 fully opens the valve device 44 of the air supply passage 33, connects the first port 97 a and the third port 97 c of the three-way valve 97, closes the second port 97 c, and closes the third port 97 ′. The first port 97a communicates with the third port 97c, and the second port 97b is closed. At the same time, the ECU 46 activates (ON) the combustion heater 17. Thereby, the air that has entered the main pipe 29 of the upstream connection pipe 25 from the air cleaner 13 follows the next route and reaches the exhaust device 7.
[0086]
{Circle around (1)} The air that has entered the main pipe 29 from the air cleaner 13 is branched into air that flows through the air supply path 33 of the branch pipe 31 for heater and air that directly flows downstream through the main pipe 29.
[0087]
{Circle around (2)} The air flowing downstream as it is through the main pipe 29 flows through the above-described air path, that is, the main pipe 29 → the compressor 15a of the turbocharger 15 → the downstream connecting pipe 27 → the intercooler 19 → the intake throttle valve 70 → the intake. The gas flows into the exhaust purification device 50 through the manifold 21 → the respective cylinders of the engine body 3 → the exhaust manifold 37 → the exhaust pipe 42 → the turbine 15 b of the turbocharger 15. Since the second port 97b of the three-way valve 97 'is closed, the intake air flowing through the downstream connection pipe 27 does not flow out to the bypass pipe 48 through the three-way valve 97'.
[0088]
{Circle around (3)} On the other hand, the air that has entered the air supply passage 33 of the heater branch pipe 31 is sent to the combustion chamber main body 43 of the combustion heater 17 via the valve device 44.
(4) The air that has entered the combustion chamber main body 43 is provided as combustion air for combustion fuel sent from the fuel supply pipe 17e in the combustion chamber 17d of the combustion chamber main body 43, and after combustion, becomes combustion gas and becomes combustion gas. Exit to the discharge path 35.
[0089]
(5) The high-temperature combustion gas that has exited the combustion gas discharge passage 35 enters the branch pipe 95 via the three-way valve 97, and further exits from the branch pipe 95 via the three-way valve 97 'to the bypass pipe 48. Therefore, in this embodiment, the two three-way valves 97 and 97 ′ can be said to be introduction means for introducing the combustion gas of the combustion heater 17 into the bypass pipe (combustion gas bypass passage) 48.
[0090]
(6) The high-temperature combustion gas that has entered the bypass pipe 48 enters the exhaust pipe 42 from the connection point C3, merges with the exhaust gas of the engine 1 that follows the path of (2), and forms the combustion gas and the exhaust gas. It becomes a mixed gas. The combustion gas of the combustion heater 17 is higher than 250 ° C., and the temperature of the mixed gas after joining at the connection point C3 is higher than the temperature of the exhaust gas discharged from each cylinder of the engine body 3.
[0091]
{Circle around (7)} The high-temperature mixed gas that has joined at the connection point C3 is exhausted after passing through the oxidation catalyst 52 and the DPF 53 of the exhaust purification device 50 in this order.
Since the second port 97b of the three-way valve 97 is closed, the combustion gas of the combustion type heater 17 does not flow toward the combustion gas cooler 84 through the three-way valve 97. It does not flow into the pipe 29. Further, since the second port 97b of the other three-way valve 97 'is closed, the combustion gas of the combustion heater 17 does not flow out to the downstream connection pipe 27. Accordingly, the entire amount of the combustion gas emitted from the combustion heater 17 can be guided to the upstream of the exhaust gas purification device 50, and the combustion gas can be effectively used for the regeneration of the DPF 53.
[0092]
Next, the ECU 46 proceeds from step 104 to step 105, in which the ECU 46 controls the operation of the fuel pump 47 and the blower fan 45 such that the combustion in the combustion chamber 17d of the combustion heater 17 generates NO at a predetermined concentration. Then, the air-fuel ratio (A / F) control of the combustion heater 17 is executed. At the same time, the flow rate of the combustion gas is controlled so that the temperature of the mixed gas flowing into the exhaust gas purification device 50 becomes 250 ° C. or higher.
[0093]
When the combustion heater 17 is operated for warming up the engine 1 or heating the passenger compartment (that is, when the combustion heater 17 is operated for purposes other than the DPF regeneration process), the combustion heater 17 is set to NO. Is operated at an air-fuel ratio in which is not generated (hereinafter, the air-fuel ratio at this time is referred to as a warm-up air-fuel ratio), and this warm-up air-fuel ratio is also in a lean range. In order to obtain a high temperature for positively generating NO in the combustion chamber 17d, the air-fuel ratio is controlled to a lean degree higher than the air-fuel ratio during warm-up. Hereinafter, the target air-fuel ratio in the air-fuel ratio control in step 105 is referred to as a DPF regeneration air-fuel ratio.
[0094]
For the DPF regeneration air-fuel ratio, an experiment is performed in advance on the exhaust gas purification device 50, and based on the experiment results, the optimal NOx concentration of the mixed gas for the regeneration of the DPF 53 is set, and then the optimal NOx concentration of the combustion gas is set. In addition, a combustion experiment is also performed on the combustion heater 17 in advance, and the air-fuel ratio of the combustion heater 17 when the NOx concentration of the combustion gas reaches the optimum NOx concentration is obtained from the experiment result. It can be a fuel ratio. In this case, the DPF regeneration air-fuel ratio becomes a constant value.
[0095]
Alternatively, the NOx concentration of the mixed gas flowing into the exhaust gas purification device 50 is detected by the NOx sensor 41 provided immediately upstream of the exhaust gas purification device 50, and the deviation between the detected NOx concentration and the preset optimal NOx concentration of the mixed gas is calculated. Based on this, the air-fuel ratio of the combustion heater 17 may be feedback-controlled so that the NOx concentration of the mixed gas becomes the aforementioned optimum NOx concentration. In this case, the DPF regeneration air-fuel ratio is variable. In the present embodiment, a method of performing feedback control of the air-fuel ratio of the combustion heater 17 is employed.
[0096]
In this way, by introducing the combustion gas of the combustion type heater 17 whose air-fuel ratio is controlled in a predetermined manner into the exhaust pipe 42 immediately upstream of the exhaust purification device 50 and mixing it with the exhaust gas, it is possible to optimize the regeneration of the DPF 53. A mixed gas having a NOx concentration and having a temperature of 250 ° C. or more can flow into the exhaust gas purification device 50. As a result, even when the temperature of the exhaust gas discharged from each cylinder of the engine body 3 is in the low temperature range L, the DPF 53 can be regenerated by the same regeneration mechanism as in the medium temperature range M.
[0097]
Further, even when the temperature of the exhaust gas discharged from each cylinder of the engine body 3 is in the low-temperature region L in the engine operating state, the temperature of the mixed gas flowing into the exhaust gas purification device 50 can be maintained at 250 ° C. or higher. Accordingly, aldehydes and the like, which are substances causing an irritating odor peculiar to the exhaust gas of a diesel engine, can be oxidized and purified by the oxidation catalyst 52, and the irritating odor of the exhaust gas finally exhausted to the atmosphere can be reduced. be able to.
[0098]
In the engine 1 for driving a vehicle, the low temperature range L corresponds to a running state in an urban area at a running speed of about 40 to 50 km / Hr from an idle running state, and is the most frequently operated in the engine 1. Since the DPF 53 can be regenerated in this operation range, clogging of the DPF 53 due to PM collection can be reduced or almost eliminated.
[0099]
Thereafter, the ECU 46 proceeds from step 105 to step 106, in which the input gas temperature detected by the input gas temperature sensor 40 is read as the DPF inlet temperature Tf, and the DPF inlet temperature Tf becomes the combustion type heater operation stop temperature Tf.₀It is determined whether it is lower. Here, the combustion type heater operation stop temperature T₀Is set to a temperature higher than 250 ° C. (for example, 280 ° C.).
[0100]
If an affirmative determination is made in step 106, the process returns to step 105 to continue the process of raising the temperature of the mixed gas by the air-fuel ratio control of the combustion heater 17.
If a negative determination is made in step 106, the process proceeds to step 107, where the ECU 46 stops (OFF) the operation of the combustion heater 17 and stops introducing the combustion gas upstream of the exhaust gas purification device 50. That is, the valve body 44a of the valve device 44 is fully closed, the first port 97a and the second port 97b of the three-way valve 97 are communicated and the third port 97c is closed, and the first port 97a and the third port of the three-way valve 97 'are closed. The second port 97b is closed by connecting the second port 97c. As a result, the combustion gas does not flow out of the combustion heater 17 and the combustion gas does not flow into the connection point C3 of the exhaust pipe 42 through the bypass passage 48. Thus, the ECU 46 ends the execution of the DPF regeneration process when the exhaust gas temperature is in the low temperature range L.
[0101]
As described above, in this embodiment, in the DPF regeneration process when the exhaust gas temperature is in the low temperature range L, the entire amount of the combustion gas from the combustion heater 17 is introduced into the exhaust purification device 50 bypassing the engine body 3. Therefore, the heat energy of the combustion gas can be effectively used for the regeneration of the DPF 53.
[0102]
Further, in this embodiment, in the DPF regeneration process when the exhaust gas temperature is in the low temperature range L, first, the EGR amount increase control is performed to increase the exhaust gas temperature. Only when the temperature (250 ° C.) is not reached, the combustion gas of the combustion type heater 17 is introduced upstream of the exhaust gas purification device 50 to supplement it, so that the fuel consumption of the combustion type heater 17 is reduced as much as possible. Is economical.
[0103]
Further, in this embodiment, when the exhaust gas temperature is equal to or higher than 250 ° C., the high-temperature combustion gas does not flow into the exhaust gas purification device 50, so that the high-temperature deterioration of the oxidation catalyst 52 can be suppressed and the durability can be improved. Is improved.
[0104]
[Second embodiment]
FIG. 7 is a configuration diagram of an internal combustion engine having a combustion heater according to a second embodiment of the present invention.
[0105]
The difference between the second embodiment and the first embodiment is that in the second embodiment, an oxidation catalyst (second oxidation catalyst) 55 is accommodated near the connection point C3 in the bypass pipe 48. The only difference is that the catalytic converter 54 is provided, and the other configuration is exactly the same as that of the first embodiment.
[0106]
This catalytic converter 54 oxidizes NO in the combustion gas to oxidize the catalytic converter 54 when the combustion gas of the combustion heater 17 is introduced upstream of the exhaust gas purification device 50 when the exhaust gas temperature is in the low temperature range L. NOx oxidized by the catalyst 55₂It is provided in order to make. Since the catalytic converter 54 is provided in the bypass pipe 48, when the exhaust gas temperature is in the middle temperature range M or the high temperature range H, the exhaust gas does not flow to the catalytic converter 54. Therefore, high-temperature deterioration of the catalytic converter 54 can be reduced, and the durability is improved.
[0107]
According to the second embodiment, the present invention is established, and the same operation and effect as those of the first embodiment can be obtained.
[0108]
【The invention's effect】
According to the internal combustion engine having the combustion heater according to the present invention, a filter provided in an exhaust system of the internal combustion engine to purify exhaust gas of the internal combustion engine, and a filter provided upstream of the filter in the exhaust system of the internal combustion engine A first oxidation catalyst, a combustion gas exhaust passage for introducing combustion gas from a combustion heater provided to heat an engine-related element of the internal combustion engine into an intake system of the internal combustion engine, and combustion of the combustion heater. A combustion gas bypass passage for introducing gas upstream of the first oxidation catalyst in an exhaust system of the internal combustion engine, bypassing a cylinder of the internal combustion engine; and a combustion gas of the combustion heater when regenerating the filter. The introduction means for introducing into the combustion gas bypass passage, it is possible to suppress the filter for exhaust gas purification provided in the exhaust system from being clogged by PM collection, as a result, It is possible to suppress the reduction in the output of the combustion engine, excellent effect is exhibited.
[0109]
Further, when the combustion gas of the combustion type heater is introduced into the combustion gas bypass passage by the introduction means when the inlet temperature of the first oxidation catalyst is equal to or lower than a predetermined temperature, the combustion type heater It is economical to avoid wasting fuel in When the inlet temperature of the first oxidation catalyst exceeds a predetermined temperature, high-temperature combustion gas does not flow through the first oxidation catalyst, so that high-temperature deterioration of the first oxidation catalyst is suppressed and durability is improved. I do.
[0110]
When the combustion of the combustion heater is controlled so that NOx is generated by combustion in the combustion heater while the combustion gas of the combustion heater is being introduced into the combustion gas bypass passage by the introduction means. The NOx generated by the combustion heater can be used for regeneration of the filter, and the regeneration of the filter can be promoted.
[0111]
A NOx sensor for detecting a NOx concentration is provided upstream of the first oxidation catalyst and downstream of a connection point between the exhaust system of the internal combustion engine and the combustion gas bypass passage, and based on the NOx concentration detected by the NOx sensor. When the air-fuel ratio of the combustion heater is controlled, the concentration of NOx flowing into the first oxidation catalyst can be controlled to a concentration optimal for regeneration of the filter, and the regeneration of the filter can be efficiently performed. It can be carried out.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a first embodiment of an internal combustion engine having a combustion heater according to the present invention.
FIG. 2 is a schematic sectional view of a three-way valve constituting a part of an introduction means in the first embodiment.
FIG. 3 is a schematic sectional view of another three-way valve constituting a part of the introduction means in the first embodiment.
FIG. 4 is a schematic sectional view of a combustion type heater as a combustion device in the first embodiment.
FIG. 5 is a temperature distribution diagram showing a relationship between an operating state of the engine 1 (engine speed and load) and an exhaust gas temperature.
FIG. 6 is a DPF regeneration process execution routine when the exhaust gas temperature is in a low temperature range in the first embodiment.
FIG. 7 is a schematic configuration diagram of a second embodiment of an internal combustion engine having a combustion heater according to the present invention.
[Explanation of symbols]
1. Engine (internal combustion engine)
3. Engine body
5. Intake device
7 Exhaust device
9 ... Heater for vehicle compartment
13 ... Air cleaner
15 ... Turbocharger
15a: Turbocharger compressor
15b: Turbocharger turbine
17. Combustion heater
17a: Cooling water passage of combustion type heater
17a₁… Cooling water inlet
17a₂… Cooling water outlet
17b ... combustion cylinder
17c ... cylindrical partition
17d: Combustion chamber
17d₁... Air supply port
17d₂… Exhaust outlet
17e ... fuel supply pipe
19. Intercooler
21 ... intake manifold
23 ... intake pipe (intake system)
25 ... upstream connecting pipe
27… Downstream connecting pipe
29… Main tube
31 ... Branch for heater
33 ... Air supply path
35 ... Combustion gas discharge path
37 ... Exhaust manifold
39 ... Main catalytic converter
40 ... Inlet gas temperature sensor
41… NOx sensor
42 ... exhaust pipe (exhaust system)
43… Combustion chamber body
43a ... Case body
44 ... Valve device
44a ... valve body
44b Drive motor
44c: Opening / closing mechanism
45… Blower fan
46 ... ECU
47 ... Fuel pump
48: Bypass passage (combustion gas bypass passage)
50 Exhaust gas purification device
51 ... casing
52: first oxidation catalyst
53 ... DPF (filter)
54: Catalytic converter
55 ... second oxidation catalyst
70 ... intake throttle valve
84: Combustion gas cooler
88 EGR device
89… EGR cooler
90 ... EGR passage
91… Temperature sensor
92 ... EGR valve
95 ... Branch pipe
97 ... three-way valve (introduction means)
97 '... three-way valve (introduction means)
C1: Connection point between the air supply passage 33 and the main pipe 29
C2: connection point between the combustion gas discharge path 35 and the main pipe 29
C3: connection point between the exhaust pipe 42 and the bypass pipe 48
W1 ... Water pipeline
W2 ... 〃
W3 ... 〃

Claims (5)

A filter provided in an exhaust system of the internal combustion engine for purifying exhaust gas of the internal combustion engine, a first oxidation catalyst provided upstream of the filter in the exhaust system of the internal combustion engine, and an engine-related element of the internal combustion engine. A combustion gas exhaust passage for introducing combustion gas from a combustion heater provided to raise the temperature into an intake system of the internal combustion engine; and a combustion gas containing NO from the combustion heater bypassing a cylinder of the internal combustion engine. A combustion gas bypass passage that is introduced upstream of the first oxidation catalyst in the exhaust system of the internal combustion engine; and an introduction unit that introduces combustion gas of the combustion heater into the combustion gas bypass passage when regenerating the filter. An internal combustion engine having a combustion-type heater, comprising: 2. The combustion according to claim 1, wherein when the inlet temperature of the first oxidation catalyst is equal to or lower than a predetermined temperature, combustion gas of the combustion type heater is introduced into the combustion gas bypass passage by the introduction means. 3. An internal combustion engine having a type heater. When the combustion gas of the combustion heater is being introduced into the combustion gas bypass passage by the introduction means, combustion of the combustion heater is controlled so that NOx is generated by combustion in the combustion heater. An internal combustion engine having the combustion heater according to claim 2. An NOx sensor for detecting a NOx concentration is provided upstream of the first oxidation catalyst and downstream of a connection point between the exhaust system of the internal combustion engine and the combustion gas bypass passage, and based on the NOx concentration detected by the NOx sensor. The internal combustion engine having a combustion type heater according to claim 3, wherein the combustion type heater controls an air-fuel ratio. The internal combustion engine having a combustion heater according to any one of claims 1 to 4, wherein a second oxidation catalyst is provided in the combustion gas bypass passage.

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