JP3525779B2 - Internal combustion engine having a combustion heater - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine having a combustion heater, and more particularly to a combustion heater for introducing combustion gas into an intake system of the internal combustion engine in order to raise the temperature of engine-related elements of the internal combustion engine. It relates to an internal combustion engine.

[0002]

2. Description of the Related Art In recent years, catalysts have been widely used as means for purifying exhaust gas discharged from internal combustion engines such as gasoline engines and diesel engines. There are oxidation catalysts, three-way catalysts, lean NOx catalysts, etc. as the exhaust gas purification catalyst. In any case, in order to obtain a predetermined purification rate, the catalyst temperature (catalyst activity Temperature) is required, and at a temperature lower than this activation temperature, the purification rate is extremely low or almost no purification is possible. The activation temperature of the catalyst is peculiar to each catalyst.

Usually, the catalyst temperature is raised by the heat of the exhaust gas discharged from the internal combustion engine, and when the internal combustion engine is started or the light load is operated, the exhaust gas temperature may become lower than the activation temperature of the catalyst. There is a problem that the catalyst temperature becomes lower than the activation temperature at that time.

On the other hand, some vehicles are equipped with a combustion heater for heating the passenger compartment in addition to an internal combustion engine as a power source. For example, JP-A-60-78819 discloses that
An air passage is provided around the combustion chamber of the combustion heater to allow air for heating the vehicle compartment to be heated by the heat of the combustion gas from the combustion heater to heat the air for heating the vehicle compartment. Air is blown into the passenger compartment through an air conditioner to heat the passenger compartment, while the combustion gas discharged from the combustion heater is introduced upstream of the catalytic converter in the exhaust system of the internal combustion engine to burn the combustion heater. A technique is disclosed in which gas is purified by a catalytic converter together with exhaust gas of an internal combustion engine and is then released into the atmosphere.

In the technique disclosed in this publication, the combustion gas from the combustion heater is introduced into the catalytic converter. However, this is for the purpose of purifying the combustion gas from the combustion heater by the catalytic converter, and is positive. It does not mean that the catalyst is warmed up. Further, there is no description about the conditions for introducing the combustion gas of the combustion heater to the upstream of the catalytic converter.

The present invention has been made in view of the above problems of the prior art, and the problem to be solved by the present invention is to burn the combustion heater only when it is necessary to warm up the catalyst. The gas is introduced into the catalyst, and the combustion of the combustion heater is controlled so that the combustion gas contains a large amount of CO. The reaction heat generated when the CO in the combustion gas is oxidized by the catalyst positively activates the catalyst. It is intended to accelerate the warm-up of the catalyst by raising the temperature to.

[0007]

The present invention adopts 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 main catalyst which is provided in an exhaust system of the internal combustion engine to purify exhaust gas of the internal combustion engine, and a combustion which is provided to raise temperature of engine-related elements of the internal combustion engine. Gas exhaust passage for introducing the combustion gas of the internal combustion engine into the intake system of the internal combustion engine, and at least a part of the combustion gas of the internal combustion engine bypassing the cylinder of the internal combustion engine and the exhaust system of the internal combustion engine. A combustion gas bypass passage introduced upstream of the main catalyst, warm-up determination means for determining whether or not warm-up is required for the main catalyst, and warm-up for the main catalyst by the warm-up determination means. Introduction means for introducing the combustion gas of the combustion type heater into the combustion gas bypass passage when it is determined that the main catalyst is required to be warmed up by the warm-up determination means. Characterized in that it comprises a combustion heater air-fuel ratio control means for combusting baked heater in the stoichiometric or rich air-fuel ratio, a.

In the internal combustion engine of the present invention configured as above, when the warm-up determination means determines that the main catalyst needs to be warmed up, the introduction means causes the high-temperature combustion gas emitted from the combustion heater to A part or all of this is introduced into the combustion gas bypass passage, and at the same time, the combustion heater air-fuel ratio control means makes the air-fuel ratio of the combustion heater stoichiometric or rich. When combustion is performed at a stoichiometric or rich air-fuel ratio in the combustion heater, carbon monoxide (CO) is generated, so that the combustion gas contains CO. The combustion gas containing CO is introduced into the exhaust system upstream of the main catalyst through the combustion gas bypass passage,
Then, it will be introduced into the main catalyst. Then,
Since CO in the combustion gas is oxidized in the main catalyst to generate reaction heat, the temperature of the combustion gas rises due to this reaction heat and the catalyst temperature of the main catalyst rises. In other words, the temperature of the main catalyst is further increased by passing through the catalyst, which is originally high in temperature, so that the temperature of the main catalyst can be raised extremely quickly.

In the present invention, the internal combustion engine may be a gasoline engine or a diesel engine, and may be a direct injection type lean burn gasoline engine or a diesel engine.

In the present invention, examples of the main catalyst include an oxidation catalyst, a three-way catalyst, and a lean NOx catalyst. The lean NOx catalyst includes a selective reduction type NOx catalyst and a storage reduction type NOx catalyst.

The selective reduction type NOx catalyst is a catalyst that reduces or decomposes NOx in the presence of hydrocarbons in an atmosphere of excess oxygen, for example, a catalyst in which a transition metal such as Cu is ion-exchanged and supported on zeolite, , A catalyst in which a noble metal is supported on zeolite or alumina, and the like.

The storage reduction type NOx catalyst determines the ratio of air and fuel (hydrocarbon) supplied to the engine intake passage and the exhaust passage upstream of the storage reduction type NOx catalyst to the exhaust gas flowing into the storage reduction type NOx catalyst. When referred to as an air-fuel ratio, it is a catalyst that absorbs NOx when the air-fuel ratio of the inflowing exhaust gas is lean, releases the absorbed NOx when the oxygen concentration in the inflowing exhaust gas decreases, and reduces it to N ₂ . This occlusion reduction type NOx catalyst uses, for example, alumina as a carrier, and on this carrier, for example, potassium K, sodium Na, lithium Li, an alkali metal such as cesium Cs, an alkaline earth such as barium Ba, calcium Ca, or lanthanum La. , At least one selected from rare earths such as yttrium Y, and a noble metal such as platinum Pt.

In the present invention, the engine-related element of the internal combustion engine whose temperature is raised by the combustion heater is engine cooling water or the internal combustion engine itself. This combustion heater is
The fuel gas is independently burned to discharge the combustion gas without being affected by the combustion in the cylinder of the internal combustion engine body.

In the present invention, the determination as to whether or not warm-up is required by the warm-up determination means is executed by the CPU (central processing unit) of the ECU (engine control unit).

In the present invention, the introducing means is for introducing the combustion gas of the combustion type heater into the combustion gas bypass passage or for inhibiting the introduction thereof, and can be constituted by a valve device. This introduction method is EC
Its operation is controlled by the U CPU.

In the present invention, the combustion-type heater air-fuel ratio control means makes the air-fuel ratio of the combustion-type heater lean, stoichiometric, or rich, and controls the supply amount of combustion fuel of the combustion-type heater. It can be performed by controlling the supply amount of the combustion air of the combustion heater, or by controlling both of them.

The air-fuel ratio when it is determined that the main catalyst needs to be warmed up and the air-fuel ratio of the combustion heater is controlled to stoichiometric or rich is the same as when the main catalyst does not need to be warmed up. It is preferable to make the rich degree larger than the air-fuel ratio during normal operation of the combustion heater. This is because the larger the amount of CO produced, the larger the heat of reaction, and the greater the effect.

In the present invention, it is preferable to provide a sub-catalyst having an oxidizing ability in the combustion gas bypass passage. With this configuration, before the combustion gas of the combustion heater is introduced into the main catalyst, CO in the combustion gas is oxidized in the sub catalyst to generate reaction heat, and the combustion gas can be heated. As a result, a rapid temperature rise in the main catalyst can be avoided, and high temperature deterioration of the main catalyst can be suppressed. The sub-catalyst only needs to have oxidizing ability,
Therefore, it is not limited to the oxidation catalyst. Since the selective reduction type NOx catalyst and the occlusion reduction type NOx catalyst also have oxidizing ability, these catalysts can also be used as the sub catalyst.

In the present invention, when the temperature of the sub-catalyst provided in the combustion gas bypass passage exceeds the activation temperature, the stoichiometric or rich air-fuel ratio control by the combustion heater air-fuel ratio control means is executed. Is preferred. Even if the air-fuel ratio of the combustion heater is stoichiometric or rich and the amount of CO in the combustion gas is increased when the temperature of the sub-catalyst is less than the activation temperature, this CO is not oxidized in the sub-catalyst and is therefore emitted as CO. This is because the amount of CO emission increases and the exhaust emission is deteriorated, and the combustion fuel of the combustion type heater is wasted.

In the present invention, the warm-up determination means can determine whether or not the main catalyst needs to be warmed up when the internal combustion engine is started. However,
This does not limit the determination timing of the warm-up determination means in the present invention at the time of engine startup, but when the necessity of warming up the main catalyst arises during engine operation, the main catalyst warm-up processing is executed. You may choose to do this.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an internal combustion engine having a combustion heater according to the present invention will be described below with reference to the drawings of FIGS.

[First Embodiment] First, the configuration of an internal combustion engine having a combustion heater according to the first embodiment will be described with reference to FIG. The engine 1 as an internal combustion engine is a water-cooled diesel engine and has an engine body 3 having a water jacket containing engine cooling water.
The engine 1 is equipped with an intake device 5 for sending air required for combustion into a plurality of cylinders (not shown) of the engine body 3, an exhaust device 7 for releasing exhaust gas into the atmosphere after combustion of the air-fuel mixture. The vehicle interior heater 9 is provided for heating the interior of the vehicle.

The intake device 5 starts with an air cleaner 13 that takes in fresh air into the cylinder and terminates an intake port (not shown) of the engine body 3. And in the meantime,
Compressor 15 of turbocharger 15 which is a supercharger
a, an intercooler 19, and an intake manifold 21 that distributes air coming through the intercooler 19 to each of the cylinders.

The constituent members of the intake device 5 are connected by a plurality of connecting pipes belonging to the intake pipe 23, which will be described below. The intake pipe 23, which is composed of a plurality of connecting pipes, is separated from the air cleaner 13 by the compressor 15a.
The downstream side connecting pipe 27 and the upstream side connecting pipe 2 which are not pressurized by the incoming intake air being forcedly pushed
It can be roughly divided into 5.

The upstream connecting pipe 25 serves as a main pipe 29 connecting the air cleaner 13 and the compressor 15a and extending linearly in the left-right direction in FIG. 1, and a tributary pipe connected to the main pipe 29 in a bypass shape. It is composed of a heater branch pipe 31.

The downstream connecting pipe 27 is a compressor 15a.
1 is an L-shaped connecting pipe that extends in the up-down direction in FIG. 1 and connects the intake manifold 21 with the intake manifold 21. The heater branch pipe 31 includes a combustion heater 17 in the middle thereof, connects the upstream side end of the combustion heater 17 and the main flow pipe 29, and supplies an air supply path 33 for supplying air to the combustion heater 17, It comprises a combustion gas discharge passage 35 which connects the downstream end of the heater 17 to the main pipe 29 and discharges the combustion gas of the combustion heater 17 to the main pipe 29. Further, each connection point C1 between the air supply passage 33 and the combustion gas discharge passage 35 and the main flow pipe 29,
As for C2, the connection point C1 is the main flow pipe 2 more than the connection point C2.
Located upstream of 9.

The upstream end of the combustion heater 17 and the main flow pipe 29
A valve device 44 is provided near the combustion heater 17 in the air supply path 33 connecting to the. As shown in FIG. 4, the valve device 44 is installed between the valve body 44a that opens and closes the air supply passage 33, the drive motor 44b that drives the valve body 44a to open and close, and between the drive motor 44b and the valve body 44a. Opening / closing mechanism section 44
The drive motor 44b is controlled by an unillustrated CPU of an engine control unit (ECU) 46 (see FIG. 1). In addition, the valve device 44 operates to close the valve body 44a when the main flow pipe 29 is throttled by the intake throttle valve 70 described later in order to positively stop the driving of the engine 1.

A combustion gas cooler 84 for cooling the combustion gas of the combustion type heater 17 is provided in the middle of the combustion gas discharge passage 35. The combustion heater 17 in the combustion gas discharge passage 35
A part connecting the downstream side end of the combustion gas cooler 84,
The downstream connecting pipe 27 is connected by a branch pipe 95. A three-way valve 97 having three ports is provided at a portion connecting the combustion gas exhaust passage 35 and the branch pipe 95. The three-way valve 97 has a structure as shown in FIG.

The three-way valve 97 connects the first port 97a, which is one of the three ports, to the downstream end of the combustion heater 17 (exhaust outlet 17d ₂ described later), and of the remaining two ports. The one second port 97b is connected to the combustion gas cooler 84 side of the combustion gas exhaust passage 35, and the remaining one third port 97c is connected to the branch pipe 95. In the case body 97d of the three-way valve 97, there is a case body 97.
A valve element 98 is provided which moves in the longitudinal direction of d by the operation of a diaphragm (not shown). This valve body 98 has two ports among the three ports, that is, the first port according to the moving position of the valve body 98 in the case body 97d.
The port 97a communicates with the second port 97b, or the first port 97a communicates with the third port 97c. Then, in that 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 97a 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 EC.
Controlled by U46.

The intake air passing through the main flow pipe 29 and the intake air branching to the air supply passage 33 at the connection point C1 and the main flow pipe 2 without branching.
9 is divided into intake air that goes downstream as it is. And
When the three-way valve 97 is controlled so as to connect the first port 97a and the second port 97b, the air supply passage 33
The intake air that branches into the intake air returns to the main pipe 29 at the connection point C2 via the air supply passage 33 → the combustion heater 17 → the combustion gas discharge passage 35 and joins the intake air that has not branched. As a result, the temperature of the intake air entering the engine body 3 is increased. Further, the three-way valve 97 has the first port 97a and the third port 97c.
When controlled so as to communicate with, the intake air branched into the air supply passage 33 flows through the air supply passage 33 → the combustion heater 17 → the branch pipe 95 and does not return to the main pipe 29.

On the other hand, in the middle of the downstream side connecting pipe 27, the intercooler 19 is provided upstream of the connection point with the branch pipe 95.
And an intake throttle valve 70. The intercooler 19 is located upstream of the intake throttle valve 70.

The intercooler 19 receives heat from the combustion heater 17 and the compressor 15a for warming the intake air in order to accelerate warm-up of the engine 1 and improve startability.
The air on the downstream side of the installation location of 5a is cooled.

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. Further, when the engine 1 is actively stopped, the intake throttle valve 70 is fully closed.

The exhaust device 7 is provided with an exhaust manifold 37 and a turbine 15b of the turbocharger 15 on an exhaust pipe 42 between an exhaust port (not shown) of the engine body 3 as a start end and a main catalytic converter 39 at the end thereof. ing. In the main catalytic converter 39,
A catalyst (main catalyst) for purifying the exhaust gas of the engine 1, for example, a selective reduction NOx catalyst is housed. The exhaust pipe 42 is provided with an inlet gas temperature sensor 40 and an outlet gas temperature sensor 41 near the inlet and outlet of the main catalytic converter 39. The incoming gas temperature sensor 40 sends an electric signal E proportional to the temperature of the gas flowing into the main catalytic converter 39.
The output gas temperature sensor 41 outputs the electric signal to the ECU 46, which is proportional to the temperature of the gas flowing out from the main catalytic converter 39.

The engine body 3 is provided with an EGR device 88 as an exhaust gas recirculation device for returning 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.

The EGR passage 90 is provided with an EGR valve 92 for controlling the amount of EGR gas passing therethrough. EGR valve 9
2 is electrically connected to the CPU of the ECU 46, and
The GR device 88 is a variable controllable valve that basically functions as an exhaust gas recirculation device and that basically opens when the engine 1 is warmed up sufficiently. Also, the EGR valve 92
Is connected to a pressure control valve (not shown) for controlling the negative pressure, such as a duty VSV. This pressure control valve receives 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, the open ratio of the EGR valve 92, from the CPU. The EGR valve 92 is driven in accordance with.

Further, the branch pipe 95 in the intake device 5 and the main catalytic converter 39 in the exhaust pipe 42 described above.
A combustion gas bypass pipe (combustion gas bypass passage, hereinafter simply referred to as a bypass pipe) 48 that bypasses the engine body 3 is connected to a portion immediately upstream of the engine main body 3. 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 incoming gas temperature sensor 40.

A sub-catalyst converter 49 accommodating an oxidation catalyst (sub-catalyst) is provided in the bypass pipe 48 near the connection point C3, and an incoming gas temperature sensor 50 is provided near the inlet of the sub-catalyst converter 49. There is. The incoming gas temperature sensor 50 outputs to the ECU 46 an electric signal proportional to the temperature of the gas flowing into the sub-catalyst converter 49.

A three-way valve 97 'having three ports is provided at a portion connecting the branch pipe 95 and the bypass pipe 48. The structure of the three-way valve 97 'is the same as the structure of the three-way valve 97 described above, and only the connection destination of the three ports is different. Therefore, the description of the structure of the three-way valve 97 'is omitted, and
Only the connection destination of the two 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.

The three-way valve 97 'has one of three ports.
The first port 97a, which is one of the two, is connected to the three-way valve 97 side of the branch pipe 95, and the second port 97b, which is one of the remaining two ports, is connected to the downstream side connecting pipe 27 side of the branch pipe 95, The third port 97c, which is the remaining one port, is connected to the bypass pipe 48. The valve body 98 of the three-way valve 97 'is the first
Port 97a communicates with second port 97b Third port 9
When 7c is closed, the combustion gas of the combustion type heater 17 introduced into the branch pipe 95 through the three-way valve 97 is the downstream side connecting pipe 2
7 to the intake manifold 21 and not to the bypass pipe 48. On the other hand, the valve body 98 of the three-way valve 97 '
When the first port 97a and the third port 97c communicate with each other and the second port 97b closes, the branch pipe 9 passes through the three-way valve 97.
The combustion gas of the combustion type heater 17 introduced in 5 flows into the bypass pipe 48 and does not flow into the downstream side connecting pipe 27. The operation of the three-way valve 97 'is also controlled by the CPU of the ECU 46.

The combustion heater 17 is a combustion device provided separately from the engine body 3 and attached to the engine 1. The combustion heater 17 is unique without being affected by combustion in a cylinder (not shown) of the engine body 3. It burns to produce combustion gas.

The operation of the combustion type 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 during cold weather, which is a temperature of about −10 ° C. to 15 ° C., and extremely cold weather, which is a temperature of −10 ° C. or less. After starting the engine, when the heat generation amount of the engine 1 itself is small (for example, when fuel consumption is small), and when the heat reception amount of the cooling water is small due to the heat generation amount of the engine 1 itself being low, further 15 ° C.
Immediately after starting at a higher normal temperature, the temperature of the cooling water is low, and the time when the engine 1 is under such conditions is “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 operates. Combustion gas of high heat comes out from there,
The combustion gas is used to warm up the engine.

The combustion heater 17 is originally a device for raising the temperature of engine-related elements such as engine cooling water in order to heat the interior of the vehicle and warm up the engine. In the present invention, however, the catalytic converter 39 is warmed up. It also functions as a facilitator. Therefore, the combustion heater 17 operates in the CPU of the ECU 46 so that the combustion heater 17 operates even when the CPU of the ECU 46 determines that the catalytic converter 39 needs to be warmed up.
Operation is controlled by. This will be described in detail later.

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 the engine cooling water. Therefore, the combustion heater 17 is provided with a cooling water passage 17a through which the engine cooling water passes. This cooling water passage 17a
Is warmed by the combustion gas flowing through the combustion chamber 17d which is a heat source.

In the combustion chamber 17d, a combustion cylinder 17b is arranged, and the combustion cylinder 17b is covered with a cylindrical partition wall 17c. By covering the combustion cylinder 17b with the partition wall 17c,
The combustion chamber 17d is defined in the case body 43d of the combustion chamber 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 wall 17c.

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, the air supply port 17d ₁ and the exhaust gas exhaust passage, respectively. It is connected at the exit 17d ₂ . Then, as described above, when the intake air branches from the main flow pipe 29 and passes through the air supply passage 33, it passes through the air supply passage 33 → the combustion chamber 17d → the combustion gas discharge passage 35 as shown by the solid arrow in FIG. Then, the intake air containing the combustion gas returns to the main flow pipe 29. Since this intake air is warmed by the combustion heat of the combustion gas, the warmed intake air is discharged until the warmed intake air is discharged from the combustion chamber main body 43 through the path indicated by the solid line arrow. The cooling water flowing through the cooling water passage 17a is heated as a heat medium. Therefore, the combustion chamber 17d can be said to be a heat exchange passage.

A fuel pump 47 is connected to the combustion cylinder 17b via a fuel supply pipe 17e serving as a fuel supply passage, and the combustion fuel is supplied to the combustion cylinder 17b by the pump pressure of the fuel pump 47. Has become. Fuel pump 4
The CPU 7 is operated and controlled by the CPU of the ECU 46 to vary the pump pressure and control the amount of combustion fuel supplied. Combustion chamber 1
When the fuel for combustion is supplied to 7d, this fuel is burned to the combustion cylinder 17
It vaporizes in b. Then, this vaporized fuel is ignited by an ignition device (not shown), and the vaporized fuel burns.

The air supply passage 3 is provided in the combustion chamber body 43.
A blower fan 45 is provided for feeding the intake air coming from the inside of the combustion cylinder 17b into the combustion cylinder 17b, and the flame F can be generated by supplying air to the combustion cylinder 17b. The blower fan 45 is controlled in operation by the CPU of the ECU 46 to vary the output, and the output adjustment adjusts the amount of air flowing in 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.

The combustion heater 17 is connected to the ECU 46.
The CPU controls the fuel pump 47 and the blower fan 45 to control the supply amount of combustion fuel and the air amount, thereby controlling the air-fuel ratio to control the combustion state, and the combustion heater 1
The output of 7 is controlled. Therefore, in this embodiment, the blower fan 45, the fuel pump 47, and the ECU 46 form a combustion type heater air-fuel ratio control means.

On the other hand, the cooling water passage 17a has a cooling water introduction port 17a ₁ and a cooling water discharge port 17a ₂ , and the cooling water introduction port 17a ₁ is connected via a water pipe W1 as shown in FIG. It is connected to a cooling water discharge port of a water jacket (not shown) of the engine body 3.

The cooling water discharge port 17a ₂ is connected to the vehicle interior heater 9 via a water pipe W 2. The vehicle interior heater 9 is connected to the cooling water introduction port of the water jacket of the engine body 3 via the water conduit W3.

Therefore, when the cooling water in the water jacket reaches the combustion type heater 17 via the water line W1, it is heated there, and thereafter, the water is cooled from the combustion type heater 17 to the water line W2.
To the heater 9 for the passenger compartment, and heat is exchanged as a heat medium of the heater 9 for the passenger compartment to emit warm air into the passenger compartment. The cooling water whose temperature has dropped due to heat exchange returns to the water jacket via the water conduit W3. In this way, the cooling water circulates among the engine body 3, the combustion heater 17, and the vehicle interior heater 9 via the water conduits W1 to W3.

Further, although the air supply passage 33 and the combustion gas discharge passage 35 are tributaries of the main flow pipe 29 belonging to the intake pipe 23, considering that they are applied only to the combustion heater 17, These tubes can be regarded as a constituent element of the combustion heater 17.

Next, the catalyst warm-up processing execution routine will be described with reference to FIG. The flowchart of the routine of the ECU 46 shown in FIG.
It is stored in the OM, and all processing in each step is executed by the CPU of the ECU 46.

First, the ECU 46 determines in step 101 whether or not the engine 1 is being started. That is, the ECU 46 turns on the ignition switch,
When the crankshaft of the engine 1 enters the cranking state, it is determined that the engine 1 has started, and if the affirmative determination is made in step 101, the process proceeds to step 102,
When a negative decision is made, the process returns. This is because in the present embodiment, the catalyst warm-up process is executed when the catalyst temperature of the main catalytic converter 39 has not reached the activation temperature when the engine 1 is started.

When the engine 1 is started, the valve element 4 of the valve device 44 provided in the air supply passage 33 of the heater branch pipe 31 is used.
4a is fully closed, the intake throttle valve 70 is fully open, the EGR valve 92 is fully closed, and the three-way valve 97 is the first port 97a and the second port 97.
b, the third port 97c is closed, the three-way valve 97 'connects the first port 97a and the third port 97c, and the second port 97b is closed, so that the combustion heater 17 is inactive (OF
F). Therefore, when the engine 1 is started, the air that has entered the air cleaner 13 follows the following path and flows from the intake device 5 to the exhaust device 7.

From the air cleaner 13 to the upstream connecting pipe 25
The air that has entered the main flow pipe 29 of No. 2 passes through the compressor 15a of the turbocharger 15 and flows to the downstream side connecting pipe 27.
It enters the intake manifold 21 through the intercooler 19 and the intake throttle valve 70.

The air that has entered the intake manifold 21 enters the cylinders of the engine body 3 and is used as combustion air for fuel. After combustion, it becomes exhaust gas and exits to the exhaust manifold 37.

The exhaust gas that has entered the exhaust manifold 37 flows into the exhaust pipe 42, and the turbocharger 15
The gas is exhausted through the turbine 15b and the main catalytic converter 39.

Since the valve device 44 is fully closed, the air flowing through the main flow pipe 25 does not flow through the heater branch pipe 31 into the combustion type heater 17, and the second port 97b of the three-way valve 97 'is closed. Since it is closed, the air flowing through the downstream side connecting pipe 27 does not flow out to the bypass pipe 48.

Next, in step 102, the ECU 46 calculates an average value of the inlet gas temperature and the outlet gas temperature detected by the inlet gas temperature sensor 40 and the outlet gas temperature sensor 41, and the average value of the main catalytic converter 39 is calculated. Catalyst temperature (Fig. 5
In the flowchart of (1), it is read as a substitute for (displayed as catalyst bed temperature).

Next, the ECU 46 proceeds to step 103 to determine whether it is necessary to raise the temperature of the main catalytic converter 39. That is, the ECU 46 determines whether or not the catalyst temperature of the main catalyst converter 39 detected in step 102 has reached a preset activation temperature of the main catalyst (for example, 200 ° C.), and the activation temperature is set to the activation temperature. When it has not reached the temperature, it is determined that the temperature of the main catalytic converter 39 needs to be raised, and when it has reached the activation temperature, it is determined that it is not necessary to raise the temperature. This is because the main catalytic converter 39 cannot purify the exhaust gas unless the catalyst temperature is equal to or higher than the activation temperature, and therefore it is necessary to raise the temperature. In this embodiment, the part of the series of signal processing by the ECU 46 that executes step 103 can be said to be warm-up determination means for determining whether or not warm-up is required for the main catalyst.

If an affirmative decision is made in step 103, the routine proceeds to step 104, where the catalyst warm-up processing after step 104 is executed, and if a negative decision is made, the routine returns.
The ECU 46 determines in step 104 that the air supply passage 3
No. 3 valve device 44 is fully opened, and the three-way valve 97 is connected to the first port 9
7a and the 3rd port 97c are connected, and the 2nd port 97c is closed. At the same time, the ECU 46 controls the combustion heater 17
Is operated (ON), and the fuel pump 47 and the blower fan 45 are controlled to operate the combustion heater 17 at a lean air-fuel ratio. As a result, the air that has entered the mainstream pipe 29 of the upstream connecting pipe 25 from the air cleaner 13 follows the next path to reach the exhaust device 7.

The air that has entered the mainstream pipe 29 from the air cleaner 13 is branched into the air flowing through the air supply passage 33 of the heater branch pipe 31 and the air flowing through the mainstream pipe 29 as it is downstream.

The air flowing through the main flow pipe 29 as it is to the downstream side is the above-mentioned air path, that is, the main flow pipe 29 → the compressor 15a of the turbocharger 15 → the downstream side connecting pipe 27 → the intercooler 19 → the intake throttle valve 70 → the intake. It flows through the manifold 21 → each cylinder of the engine body 3 → the exhaust manifold 37 → the exhaust pipe 42 → the turbine 15b of the turbocharger 15 to the main catalytic converter 39.

On the other hand, the air supply path 3 of the heater branch pipe 31
The air entering 3 is sent to the combustion chamber main body 43 of the combustion heater 17 via the valve device 44. The air that has entered the combustion chamber main body 43 is provided as combustion air for the combustion fuel sent from the fuel supply pipe 17e in the combustion chamber 17d of the combustion chamber main body 43, and becomes combustion gas after combustion to form the combustion gas discharge passage 35. Go to. This combustion heater 1
The temperature of the combustion gas emitted from the main catalytic converter 3
9 much higher than the activation temperature of 9 (eg 400-
500 ° C or higher).

The high-temperature combustion gas discharged to the combustion gas discharge passage 35 enters the branch pipe 95 via the three-way valve 97, and further passes from the branch pipe 95 via the three-way valve 97 'to the bypass pipe 48.
Go to. Therefore, in this embodiment, the two three-way valves 9
7, 97 'can be said to be an introduction means for introducing the combustion gas of the combustion heater 17 into the bypass pipe (combustion gas bypass passage) 48.

The high-temperature combustion gas that has entered the bypass pipe 48 enters the sub-catalyst converter 49 and warms it, and then enters the exhaust pipe 42 from the connection point C3 and joins the exhaust gas of the engine 1 that follows the above-mentioned path. And becomes a mixed gas. The exhaust gas of the engine 1 before joining at the connection point C3 is not so high in temperature immediately after the engine is started, but the combustion gas of the combustion heater 17 is extremely high in temperature, so that the mixture after joining at the connection point C3 is mixed. The gas temperature is much higher than the exhaust gas temperature.

The high temperature mixed gas, which has merged at the connection point C3, enters the main catalytic converter 39 to warm it, and is then exhausted. The second port 97b of the three-way valve 97
Is closed, the combustion gas of the combustion heater 17 does not flow through the three-way valve 97 toward the combustion gas cooler 84, and therefore the combustion gas does not flow out of the branch pipe 35 to the main flow pipe 29. Also, another three-way valve 9
Since the second port 97b of 7'is closed, the air flowing through the downstream side connecting pipe 27 does not flow out to the bypass pipe 48, and the combustion gas of the combustion type heater 17 is discharged from the downstream side connecting pipe 27.
It doesn't flow to As a result, the combustion heater 17
The combustion gas emitted from the exhaust gas can be effectively used to raise the temperature of the main catalytic converter 39.

Next, the ECU 46 proceeds from step 104 to step 105 to read the incoming gas temperature detected by the incoming gas temperature sensor 50 as a substitute for the catalyst temperature of the sub catalytic converter 49.

Next, in step 106, the ECU 46 determines whether or not the catalyst temperature of the sub-catalyst converter 49 is equal to or higher than the preset activation temperature of the sub-catalyst (for example, 150 ° C.). If an affirmative decision is made in step 106, the operation proceeds to step 107, and if a negative decision is made, the operation returns to step 105. Sub catalytic converter 49
Is, as will be described later, carbon monoxide (CO) in the combustion gas.
Is provided for the purpose of further raising the temperature of the combustion gas by the reaction heat generated at that time, and if the catalyst temperature of the sub-catalyst converter 49 is not higher than the activation temperature of the sub-catalyst, the sub-catalyst converter is activated. 49 cannot function in this way.

The ECU 46, in step 107,
The fuel pump 47 and the blower fan 4 are arranged so that the air-fuel ratio (A / F) of the combustion heater 17 becomes stoichiometric or rich.
The operation control of No. 5 is performed (hereinafter, this is referred to as A / F rich control). The combustion heater 17 normally operates at a lean air-fuel ratio, and CO is hardly generated when operating at a lean air-fuel ratio. However, if combustion is performed at stoichiometric or rich air-fuel ratio, C in the combustion chamber 17d
O is produced, and this CO comes to be contained in the combustion gas. As a result, the combustion gas containing CO passes through the path described above, that is, the combustion heater 17 → the three-way valve 97.
-> Branch pipe 95-> Three-way valve 97 '-> Bypass pipe 48 to enter the sub-catalyst converter 49. At this time, since the catalyst temperature of the sub-catalyst converter 49 is equal to or higher than the activation temperature of the sub-catalyst, CO in the combustion gas is oxidized in the sub-catalyst converter 49 and becomes CO ₂ . And CO
As the temperature of the combustion gas rises further due to the heat of reaction generated when is oxidized to CO ₂ , the combustion gas whose temperature has risen merges with the exhaust gas from each cylinder of the engine body 3 at the connection point C 3 to form a mixed gas. , The temperature of the mixed gas increases. The mixed gas thus heated passes through the main catalytic converter 39, so that the catalyst temperature of the main catalytic converter 39 is further increased.

The A / F rich control of the combustion heater 17 may be controlled to a preset constant rich degree, but as the rich degree of the air-fuel ratio of the combustion heater 17 increases, Since the amount of CO in the combustion gas increases and the amount of reaction heat generated in the sub-catalytic converter 49 is determined according to the amount of CO, the amount of CO is rich according to the temperature difference between the catalyst temperature of the main catalytic converter 39 and the activation temperature of the main catalyst. The degree may be variably controlled.

Next, the ECU 46 proceeds from step 107 to step 108 to detect the catalyst temperature of the main catalytic converter 39. The procedure for detecting the catalyst temperature of the main catalytic converter 39 is the same as that in step 102.

Next, the ECU 46 proceeds to step 109 to determine whether or not it is necessary to raise the temperature of the main catalytic converter 39. That is, the ECU 46 determines whether or not the catalyst temperature of the main catalytic converter 39 detected in step 108 is equal to or higher than a preset predetermined temperature (hereinafter, this temperature is referred to as catalyst warm-up stop temperature), and the catalyst warm-up is performed. When the temperature is equal to or higher than the engine stop temperature, it is determined that the temperature rise of the main catalytic converter 39 is not necessary, and when the temperature is lower than the catalyst warm-up stop temperature, it is determined that the temperature rise of the main catalytic converter 39 is still necessary. . The catalyst warm-up stop temperature is equal to or higher than the activation temperature of the main catalytic converter 39 (for example, 200 ° C.).

When a negative determination is made in step 109, the process returns to step 107, the rich control operation of the combustion type heater 17 is continued, and the catalyst warm-up of the main catalytic converter 39 is continued.

If an affirmative decision is made in step 109, the routine proceeds to step 110, where the ECU 46 determines that the combustion heater 17
Is stopped (OFF), 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 with each other, and the third port 97c is closed. As a result, the combustion gas does not come out of the combustion heater 17, and the combustion gas does not come out to the connection point C3 of the exhaust pipe 42 through the bypass passage 48. Then, only the exhaust gas emitted from each cylinder of the engine body 3 enters the main catalytic converter 39 through the exhaust pipe 42. At this time, since the catalyst temperature of the main catalytic converter 39 has already reached the activation temperature of the main catalyst or higher, HC, CO, NO in the exhaust gas
x is purified by the main catalytic converter 39, and the purified exhaust gas is discharged. With this, EC
U46 ends the catalyst warm-up process.

As described above, in the catalyst warm-up process for the main catalytic converter 39 in this embodiment, the total amount of the combustion gas of the combustion type heater 17 is introduced into the main catalytic converter 39 while bypassing the engine body 3. The heat energy of the combustion gas can be effectively used for catalyst warm-up.

Further, the amount of CO in the combustion gas is increased by the A / F rich control of the combustion heater 17, the CO in the combustion gas is oxidized by the sub-catalyst converter 49, and the reaction heat generated at that time causes the temperature of the combustion gas to rise. Is further increased, the catalyst can be warmed up to the main catalytic converter 39 more quickly. Moreover, since the sub catalytic converter 49 is arranged immediately upstream of the main catalytic converter 39, the energy loss from the sub catalytic converter 49 to the main catalytic converter 39 is very small, and the heat obtained in the sub catalytic converter 49 is small. Energy can be used for catalyst warm-up without waste.

Further, in this embodiment, until the sub-catalyst converter 49 can oxidize CO, that is, until the catalyst temperature of the sub-catalyst converter 49 reaches the activation temperature of the sub-catalyst, the combustion heater 17 is set to the lean air-fuel ratio. Since the engine is operated at 1, the exhaust emission during that time is not deteriorated, and the waste of the combustion fuel of the combustion heater can be prevented. Even if CO is generated in the combustion gas by making the air-fuel ratio of the combustion heater 17 stoichiometric or rich when the catalyst temperature of the sub-catalytic converter 49 is lower than the activation temperature, this CO is not oxidized in the sub-catalytic converter 49. , CO will be discharged as it is, and C
The amount of O 2 emission increases, exhaust emission deteriorates, and the combustion fuel of the combustion heater is wasted. This does not occur in this embodiment.

Further, in this embodiment, since the sub-catalyst converter 49 is provided in the bypass pipe 48,
Before the mixed gas containing the combustion gas of the combustion heater 17 enters the main catalytic converter 39, the sub catalytic converter 49
In, the CO in the mixed gas can be oxidized to generate reaction heat to heat the mixed gas, and as a result, a rapid temperature rise in the main catalytic converter 39 can be avoided, and the high temperature deterioration of the main catalytic converter 39 can be prevented. Can be suppressed.

After the completion of the catalyst warm-up process for the main catalytic converter 39, the combustion heater 17 operates in the ECU 4
6 follows the normal operation control during operation of the engine 1. That is, when it is necessary to heat the vehicle interior and when the engine 1 is in a predetermined operating state as described above,
The ECU 46 operates the combustion heater 17. In this case, the ECU 46 operates the combustion heater 17 at a lean air-fuel ratio, fully opens the intake throttle valve 70, and connects the first port 97a and the second port 97b of the three-way valve 97 to the third port 97.
c is closed, the first port 97a and the third port 97c of the three-way valve 97 'are communicated with each other, and the second port 97b is closed.

When the port connection state of the three-way valve 97 is as described above, the combustion gas of the combustion type heater 17 can flow to the main flow pipe 29 through the combustion gas discharge passage 35, but the branch pipe. It will be impossible to flow to 95.

Further, the EGR valve 92 and the valve element 44a of the valve device 44 may be open or closed.
This differs mainly when the engine 1 is not warmed up yet and when it is sufficiently warmed up.

When the former engine 1 is not sufficiently warmed up, the EGR valve 92 is closed and the valve element 44a is opened. In this way, the air that has entered the intake device 5 from the air cleaner 13 reaches the exhaust device 7 along the following path.

The air that has entered the mainstream pipe 29 of the intake pipe 23 from the air cleaner 13 is branched into the air flowing through the air supply passage 33 of the heater branch pipe 31 and the air flowing through the mainstream pipe 29 as it is downstream.

The air that has entered the air supply passage 33 is sent to the combustion chamber body 43 of the combustion type heater 17 after passing through the valve device 44. The air that has entered the combustion chamber main body 43 is provided as combustion air for the combustion fuel sent from the fuel supply pipe 17e in the combustion chamber 17d of the combustion chamber main body 43, and becomes combustion gas after combustion to form the combustion gas discharge passage 35. Go to.

The high temperature combustion gas discharged to the combustion gas discharge passage 35 enters the main flow pipe 29 from the connection point C2 of the main flow pipe 29 via the three-way valve 97 and the exhaust gas cooler 84, and flows into the main flow pipe 29 without branching. Combines with the flowing air to raise the temperature of the intake air.

The intake air whose temperature has been raised 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, and passes through the inside of the cylinder of the engine body 3 to reach the exhaust manifold 37. Exhaust pipe 42,
The gas is exhausted through the turbine 15b of the turbocharger 15 and the catalytic converter 39.

As described above, since the high-heat combustion gas of the combustion heater 17 enters the cylinder of the engine body 3, the engine 1 is warmed up. When the latter engine 1 is sufficiently warmed up, the EGR valve 92 is opened and the valve element 44a is closed. This is because the engine 1 is warmed up sufficiently, so EGR
In order to perform the original exhaust gas recirculation of the device 88, it is necessary to open the valve body 44a and send the high-heated combustion gas emitted by the combustion heater 17 to the engine body 3 even though the engine 1 is sufficiently warmed up. Because there is no.

It should be noted that there is no compressor 15a in the 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 flow pipe 29, and the compressor 15a does not operate in that portion. Therefore, the pressure at the connection point C2 side does not become higher than that at the connection point C1, and moreover, the blower fan 45 of the combustion heater 17 sucks air through the air supply path 33, so that the air supply path 33 And the combustion chamber 1 of the combustion type heater 17 connected to the main flow pipe 29 via the combustion gas discharge passage 35
No backflow occurs in 7d. Therefore, the flashback phenomenon in which the flame direction of the combustion heater 17 faces the air supply passage 33 side does not occur.

[Second Embodiment] FIG. 6 is a configuration diagram of an internal combustion engine having a combustion heater according to a second embodiment of the present invention.

The second embodiment differs from the first embodiment only in that the second embodiment does not have the sub-catalyst converter 49 and the incoming gas temperature sensor 50 upstream thereof. The other configurations are exactly the same as those of the first embodiment.

The present invention is also realized by the second embodiment in which the sub-catalyst converter 49 is not provided, and the same action and effect as in the case of the first embodiment can be obtained. The reason is that the selective reduction type NOx catalyst as the main catalyst housed in the main catalytic converter 39 also has an oxidizing ability and oxidizes CO to generate reaction heat at that time. This is because the temperature at which the reducing NOx catalyst can oxidize CO is lower than the temperature at which HC, NOx, etc. can be purified.

Therefore, the combustion type heater 1 containing CO
When the mixed gas of the combustion gas and the exhaust gas of No. 7 enters the main catalytic converter 39, the main catalytic converter 39
In, the CO in the mixed gas is oxidized, and the temperature of the mixed gas rises due to the reaction heat at that time, and as a result, the catalyst temperature of the main catalytic converter 39 rises.

Since the NOx storage reduction catalyst also has an oxidizing ability, the same effect can be obtained even when the NOx storage reduction catalyst is used as the main catalyst instead of the selective reduction NOx catalyst.

[0097]

According to the internal combustion engine having the combustion heater according to the present invention, the main catalyst provided in the exhaust system of the internal combustion engine for purifying the exhaust gas of the internal combustion engine and the engine-related element of the internal combustion engine are elevated. A combustion gas exhaust passage for introducing the combustion gas of the combustion heater provided for warming into the intake system of the internal combustion engine, and at least a part of the combustion gas of the combustion heater bypassing the cylinder of the internal combustion engine. A combustion gas bypass passage introduced upstream of the main catalyst of the exhaust system of the internal combustion engine;
Warm-up determination means for determining whether or not warm-up is required for the main catalyst, and combustion of the combustion heater when the warm-up determination means determines that warm-up is required for the main catalyst. Introducing means for introducing gas into the combustion gas bypass passage, and combustion for burning the combustion type heater at a stoichiometric or rich air-fuel ratio when the warm-up determination means determines that warm-up is required for the main catalyst. By providing the type heater air-fuel ratio control means, the main catalyst can be quickly warmed up, and the excellent effect that the discharge of unpurified exhaust gas can be extremely reduced is achieved.

When a sub-catalyst having an oxidizing ability is provided in the combustion gas bypass passage, there is an effect that deterioration of the main catalyst can be suppressed. When the stoichiometric or rich air-fuel ratio control by the combustion-type heater air-fuel ratio control means is executed when the temperature of the sub-catalyst provided in the combustion gas bypass passage exceeds the activation temperature, the main catalyst It is possible to prevent the emission of exhaust gas from deteriorating while the engine is warming up, and to prevent waste of fuel in the combustion heater.

[Brief description of 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 cross-sectional view of a three-way valve that constitutes a part of the introducing means in the first embodiment.

FIG. 3 is a schematic cross-sectional view of another three-way valve that constitutes a part of the introducing means in the first embodiment.

FIG. 4 is a schematic cross-sectional view of a combustion type heater as a combustion device in the first embodiment.

FIG. 5 is a catalyst warm-up processing execution routine for the main catalyst in the first embodiment.

FIG. 6 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]

DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine) 3 ... Engine main body 5 ... Intake device 7 ... Exhaust device 9 ... Cabin heater 13 ... Air cleaner 15 ... Turbocharger 15a ... Turbocharger compressor 15b ... Turbocharger turbine 17 ... Combustion heater 17a ... Cooling water passage 17a ₁ of combustion heater ... Cooling water inlet 17a ₂ ... Cooling water discharge port 17b ... Combustion tube 17c ... Cylindrical partition 17d ... Combustion chamber 17d ₁ ... Air supply port 17d ₂ ... Exhaust discharge port 17e ... Fuel Supply pipe 19 ... Intercooler 21 ... Intake manifold 23 ... Intake pipe (intake system) 25 ... Upstream connecting pipe 27 ... Downstream connecting pipe 29 ... Main flow pipe 31. Heater branch pipe 33 ... Air supply passage 35 ... Combustion gas discharge Line 37 ... Exhaust manifold 39 ... Main catalytic converter 40 ... Incoming gas temperature sensor 42 ... Exhaust pipe (exhaust system) 4 ... combustion chamber body 43a ... case body 44 ... valve device 44a ... valve body 44b ... driving motor 44c ... opening / closing mechanism 45 ... blower fan (combustion type heater air-fuel ratio control means) 46 ... ECU 47 ... fuel pump (combustion type heater empty) Fuel ratio control means) 48 ... Bypass passage (combustion gas bypass passage) 49 ... Sub catalytic converter 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 ... 3-way valve (introducing means) 97 '... 3-way valve (introducing means) C1 ... Connection point between air supply passage 33 and main pipe 29 C2 ... Connection point W1 between combustion gas exhaust passage 35 and main pipe 29 ... Water pipe W2 ... 〃 W3 ... 〃

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) F01N 3/08-3/36 B60H 1/22 F02N 17/00

Claims (4)

(57) [Claims] 1. A main catalyst provided in an exhaust system of an internal combustion engine for purifying exhaust gas of the internal combustion engine, and combustion gas of a combustion type heater provided to raise an engine-related element of the internal combustion engine as the internal combustion engine. Combustion gas exhaust passage introduced into the intake system of the engine, and combustion introducing at least part of the combustion gas of the combustion type heater into the exhaust system of the internal combustion engine upstream of the main catalyst by bypassing the cylinder of the internal combustion engine. A gas bypass passage, warm-up determination means for determining whether or not warm-up is required for the main catalyst, and the warm-up determination means for determining whether or not warm-up is required for the main catalyst. Introducing means for introducing the combustion gas of a combustion heater into the combustion gas bypass passage; and the combustion heater when the warm-up determination means determines that the main catalyst needs to be warmed up. Internal combustion engine having a combustion heater, characterized in that it comprises a combustion heater air-fuel ratio control means for burning a rich air-fuel ratio. 2. The internal combustion engine having a combustion heater according to claim 1, wherein a sub catalyst having an oxidizing ability is provided in the combustion gas bypass passage. 3. The stoichiometric or rich air-fuel ratio control is executed by the combustion-type heater air-fuel ratio control means when the temperature of the sub-catalyst provided in the combustion gas bypass passage exceeds an activation temperature. An internal combustion engine having the combustion heater according to claim 2. 4. The warm-up determination means determines whether or not the main catalyst needs to be warmed up when the internal combustion engine is started. Internal combustion engine having a combustion heater.