JP2000186630A - Internal combustion engine having combustion heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the appropriate combustion of an internal combustion engine by controlling recycled exhaust gas in an EGR system to an appropriate temperature. SOLUTION: In this internal combustion engine having an intake system introducing fresh air to the inside of an engine and an exhaust system exhausting exhaust gas produced by burning fuel in the inside of the engine, and also having an exhaust recirculating passage 81 returning exhaust gas exhausted from the exhaust system to the intake system by bypassing the internal combustion engine, and further having a combustion heater 22 arranged to heat an engine related element by heat obtained by burning fuel, a heat exchanger 84 performing heat exchange in exhaust gas flowing in the inside of the exhaust recirculating passage 81 is arranged in the middle of the exhaust recirculating passage 81, the combustion heater 22 is connected as a heat source to the heat exchanger 84 and exhaust gas flowing in the inside of the exhaust recalculating passage 81 is heated by the heat exchanger 84 according to the driving conditions of the internal combustion engine, thus deterioration of combustion can be prevented.

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 provided with a combustion type heater for raising the temperature of components related to the engine. More specifically, the present invention relates to a technology for using combustion gas of a combustion heater.

[0002]

2. Description of the Related Art In recent years, internal combustion engines have high thermal efficiencies, such as direct injection engines and diesel engines, for example, and the amount of excess heat discharged is small. Therefore, a combustion type heater is provided separately from the internal combustion engine to heat engine-related elements such as a heater core when the engine is started.

[0003] As long as such a combustion heater is provided, it is desired to use the exhaust gas efficiently.
On the other hand, it is known to provide an exhaust gas recirculation device (so-called EGR device) for returning exhaust gas from an exhaust system to an intake system for the purpose of reducing NOx in the exhaust gas.

[0004] As such an EGR device, for example, a device described in JP-A-7-317608 is known. Here, in addition to the exhaust gas recirculation operation area detecting means for detecting whether or not the operation area is for performing exhaust gas recirculation, an exhaust gas recirculation path cooling means for cooling the exhaust gas recirculation path is provided, Since the exhaust gas is cooled by the cooling means before entering the intake system, the exhaust gas temperature at the time of entering the intake system is sufficiently low.

[0005]

By the way, in such an apparatus, the exhaust gas circulation passage cooling means for cooling the exhaust gas recirculation passage utilizes cooling water for cooling the internal combustion engine. Since this cooling water has not yet been warmed at the time of starting the internal combustion engine, the exhaust gas passing through the EGR device is supercooled by such cooling water, and the situation that the combustion in the internal combustion engine deteriorates may occur. Occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to control the temperature of recirculated exhaust gas in an EGR device to an appropriate temperature to ensure appropriate combustion of an internal combustion engine. It is an object of the present invention to utilize the heat of a combustion type heater in realizing this.

[0007]

Means for Solving the Problems In order to solve the above problems, the present invention employs the following means. That is, in an internal combustion engine having a so-called EGR device, when the temperature of the exhaust gas recirculated by the EGR device is too low, the exhaust gas is heated by the heat of the combustion heater.

More specifically, the engine has an intake system for introducing fresh air into the engine, an exhaust system for discharging exhaust gas generated by fuel combustion in the engine, and exhaust gas discharged from the exhaust system. A combustion system provided with an exhaust gas recirculation passage (EGR passage) for returning gas to the intake system by bypassing the internal combustion engine, and further provided for raising the temperature of engine-related elements by heat obtained by burning fuel; In an internal combustion engine having a heater,
In the middle of the EGR passage, there is provided a heat exchanger for exchanging heat with exhaust gas flowing through the EGR passage, and the combustion type heater is connected to this heat exchanger as a heat source, and the heat exchanger is connected in accordance with an operation state of the internal combustion engine. The exhaust gas flowing in the exhaust gas recirculation passage is heated by the heat of the combustion heater by the heat exchanger.

Here, it is preferable to further comprise a heat exchanger control means for judging an operation state of the internal combustion engine and issuing an exhaust gas heating command by the heat exchanger according to the operation state. Further, the heat exchanger may also serve as a cooling unit for cooling the exhaust gas passing through the exhaust gas recirculation passage. When high-temperature exhaust gas is introduced into the intake system by the EGR control, the mass of the exhaust gas contained per unit volume is reduced and the volume efficiency is reduced. To cool.

In order to use the heat exchanger as a heating device and also as a cooling device, a first cooling water introduction path for introducing cooling water heated by a combustion type heater into the heat exchanger, and a combustion type heater. A second cooling water introduction passage for introducing unheated cooling water into the heat exchanger; and switching means for switching between the first cooling water passage and the second cooling water passage in accordance with an operation state of the internal combustion engine. It is good to do so.

[0011] The cooling water not heated by the combustion type heater is as follows.
This is cooling water when the cooling water from the internal combustion engine is sent to the heat exchanger without heating, or cooling water sent from the radiator to the heat exchanger as it is.

The temperature of the exhaust gas flowing through the exhaust gas recirculation passage can be controlled to a predetermined temperature range by heating or cooling the gas with the heat exchanger. The temperature of the exhaust gas used in the EGR control is optimally about 100 ° C.
The temperature of the cooling water during operation of the internal combustion engine is about 80 ° C. However, when the temperature of the cooling water of the internal combustion engine is about 20 ° C. at the time of starting the internal combustion engine, the startability of the internal combustion engine deteriorates. Therefore, when the exhaust gas flowing in the exhaust gas recirculation passage is heated by the heat of the combustion type heater by the heat exchanger, the temperature of the fuel-air mixture can be increased to prevent combustion deterioration, and the heated exhaust gas flowing into the internal combustion engine can be prevented. The temperature of the internal combustion engine is raised by the gas, and the startability is improved.

In the present invention, the term "internal combustion engine" refers to not only a normal port injection gasoline engine but also a gasoline direct injection lean burn engine, a diesel engine or a CNG (com) engine.
Also includes internal combustion engines, such as mpressed natural gas engines, in which the atmosphere in the exhaust system is excessive in oxygen and low in hydrocarbons and carbon monoxide.

The combustion type heater is a heater attached to the internal combustion engine as a separate object from the internal combustion engine main body. The combustion type heater performs its own combustion without being affected by the combustion in the cylinder of the internal combustion engine main body to generate combustion gas. To discharge. Since it is necessary to raise the temperature of the engine-related elements before the engine is started, it is provided separately from the internal combustion engine body.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an internal combustion engine according to the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which the exhaust gas purification device according to the present embodiment is applied. The internal combustion engine shown in FIG. 1 is a multi-cylinder water-cooled diesel engine.

The diesel engine has an engine body 1 having a water jacket containing engine cooling water, an intake device 2 for feeding air required for combustion into a plurality of cylinders of the engine body 1, and an exhaust gas after combustion of the air-fuel mixture. It has an exhaust device 3 for releasing gas into the atmosphere, and a heater core 4 of a heating device for warming the interior of a vehicle equipped with an engine.

The intake device 2 includes an air cleaner 5 for filtering intake air, an aero flow meter 5a for measuring the flow rate of intake air passing through the air cleaner 5, a compressor 6a of a turbocharger 6 for pumping the intake air, and the compressor 6a. An intercooler 7 that cools intake air heated by heat generated when the air is compressed at 6a, and an intake manifold 8 that sends intake air that has passed through the intercooler 7 to each cylinder of the engine body 1. These are connected to each other by an intake pipe 9. Further, an intake throttle valve 11 is arranged between the intercooler 7 and the engine body 1.

The exhaust device 3 includes an exhaust manifold 12 connected to an exhaust port of the engine body 1,
The exhaust pipe 14 includes a turbine 6b of the turbocharger 6, an exhaust purification catalyst 13 for purifying exhaust gas, and a muffler (not shown) connected to the catalyst 13. In this example, the exhaust purification catalyst 13 includes a NOx catalyst 13a on the upstream side and an oxidation catalyst 13b on the downstream side. As the NOx catalyst, a selective reduction type lean NOx catalyst and a storage reduction type lean NOx catalyst can be exemplified.

The selective reduction type lean NOx catalyst refers to an oxygen-excess atmosphere (lean atmosphere) and a hydrocarbon (H
A catalyst that reduces or decomposes NOx in the presence of C), and examples thereof include a catalyst in which a transition metal such as Cu is ion-exchanged on zeolite and a catalyst in which a noble metal is supported on zeolite or alumina. Selective reduction type N
The Ox catalyst has a catalyst bed temperature within the catalyst purification window,
If the air-fuel ratio of the inflowing exhaust gas is lean, and HC, preferably HC whose molecular size has been reduced by thermal decomposition, is present in the exhaust gas, a part of the HC is partially oxidized to form active species. The generated active species react with NOx in the exhaust gas to reduce NOx to N ₂ , H ₂ O, CO _{2 and the} like.

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

The oxidation catalyst oxidizes components of the reducing agent (fuel in the case of diesel) which have not been consumed, ie, components such as HC and CO, and discharges them as CO ₂ and water.

The selective reduction type lean NOx catalyst exerts purification ability when the catalyst bed temperature is within a predetermined temperature range (catalyst purification window). This point is due to the occlusion reduction type lean NOx catalyst and oxidation catalyst. The same is true for

Further, the exhaust pipe 14 upstream of the catalyst 13
Above, the turbine 6b of the turbocharger 6 is provided. The turbine 6b is provided with a variable nozzle vane that controls the turbine speed by adjusting the flow of exhaust gas introduced into the turbine 6b. This variable nozzle vane converts the negative pressure from the vacuum pump 41 into an electric vacuum regulating valve (EVR).
V) It is variably controlled by adjusting at 42 and driving the actuator 43.

Next, the combustion type heater 22 will be described. As shown in FIG. 1, a branch pipe 31 for a heater is provided branching from an intake pipe 9 connecting the air cleaner 5 and the compressor 6 a of the turbocharger 6. It is connected.

The combustion heater 22 heats a heat medium (cooling water) by heat generated by burning fuel separately from the engine, and uses the heat medium as an engine-related element to form the heater core 4 or the engine body 1. And heat generated thereby heats these engine-related elements. Therefore, the heat medium (cooling water) is supplied from the combustion type heater 22 via the heater core 4 and the water jacket of the engine body 1.
The heat medium circulation path which circulates is provided.

As such a heat medium circulating path, the combustion type heater 22 is provided with engine cooling water.
2 is connected to a cooling water discharge passage 33 that guides the cooling water heated in the combustion type heater 22 to the engine body 1 via the heater core 4.

Here, a specific configuration of the combustion type heater 22 will be described with reference to FIG. Inside the combustion type heater 22, a heater internal cooling water passage 22a communicating with a cooling water introduction passage 32 and a cooling water discharge passage 33 is formed for flowing cooling water from the water jacket.

The heater internal cooling water passage 22a is disposed so as to circulate around a combustion chamber 22d formed inside the combustion type heater 22, and cooling water flowing through the heater internal cooling water passage 22a is supplied from the combustion chamber 22d. The temperature rises due to the heat.

The combustion chamber 22d includes a combustion cylinder 22b as a combustion source for generating a flame, and a cylindrical partition wall 22c that covers the combustion cylinder 22b to prevent the flame from leaking to the outside. In this way, the combustion cylinder 22b is
By covering with c, the combustion chamber 22d is defined in the partition wall 22c. The partition wall 22c is covered by the outer wall 24 of the combustion type heater 22. The partition 22
An annular gap is provided between c and the outer wall 24, and this gap functions as the above-described heater internal cooling water passage 22a.

The combustion type heater 22 has an air supply port 22e.
And an exhaust outlet 22f, and the air supply port 22e and the exhaust outlet 22f communicate with the combustion chamber 22d. The heater branch pipe 31 is connected to the air supply port 22e for introducing the intake air.
2 f is connected to the exhaust pipe 15 via the combustion gas discharge pipe 51 on the upstream side of the catalyst 13. Therefore, the combustion gas discharged from the exhaust outlet 22 f is introduced into the exhaust pipe 14 and flows into the catalyst 13.

Next, the exhaust gas branches off from the exhaust pipe 14 between the exhaust manifold 12 and the turbine 6b of the turbocharger 6, and connects to the intake pipe 9 between the intake throttle valve 11 and the intake manifold 8. An EGR pipe 81 is provided as a recirculation passage.

In the middle of the EGR pipe 81, an electric vacuum regulating valve (EVRV) 8
An EGR control valve 83 is provided, which is driven by a negative pressure from the vacuum pump 41 through the EGR control valve 2. Furthermore, EGR
The EGR pipe 81 downstream of the control valve 83 is provided with a heat exchanger 84 as a heating / cooling device that heats or cools the exhaust gas by exchanging heat with the exhaust gas passing through the EGR pipe 81.

The heat exchanger 84 includes a combustion type heater 22 as a heat source and a cooling water passage 33 as a first cooling water passage.
The cooling water warmed in the combustion heater 22 flows through a heat exchange coil provided in the heat exchanger 84.

The heat exchanger 84 is also a water-cooled cooler using cooling water sent from a water jacket of the engine. When the internal combustion engine is under a high load, it is preferable that the exhaust gas recirculated by the EGR control has a low temperature. This is because, when high-temperature exhaust gas is introduced into the intake system, the mass of the exhaust gas contained per unit volume is reduced and the volume efficiency is reduced. Therefore, to prevent this and improve the volumetric efficiency, the exhaust gas is cooled by a water-cooled cooler.

When the cooling water heated in the combustion type heater 22 flows through the heat exchanger 84, the heat exchanger 84 functions as a heating device, and the cooling water not heated by the combustion type heater 22 is charged in the heat exchanger 84. , The heat exchanger 84 functions as a cooling device. Therefore, whether the heat exchanger 84 is used as a heating device or a cooling device depends on whether to use cooling water heated by a combustion heater or to use cooling water that is not heated.

The presence or absence of the heating may be determined depending on whether or not the combustion type heater is operated, and a first cooling water passage passing through the combustion type heater and a second cooling water passage not passing through the combustion type heater. Heat exchanger 8 by water passage and switching control valve
4 may be selectively connected.

Further, the selection of the first cooling water passage and the second cooling water passage by the switching control valve is performed in accordance with the operation state of the internal combustion engine, and when both water passages are separately provided, respectively. A switching control valve may be provided, and when both water paths are merged on the way, a switching control valve may be provided at the junction.

The EVRV 82 is duty-controlled by the ECU 18 according to the operating condition of the engine, and varies the negative pressure from the vacuum pump 41 according to the duty ratio.
The negative pressure applied to the diaphragm chamber of the GR control valve 83 is controlled. The opening amount of the EGR control valve 83 changes depending on the magnitude of the negative pressure. The EGR control valve 83 is a flow control valve that controls the flow rate of the exhaust gas. The ECU 18 and the EVRV 82 constitute control valve adjusting means for adjusting the opening of the valve according to the operating state of the internal combustion engine.

The ECU 18 has a cooling water temperature THW flowing through a water jacket of the internal combustion engine, an engine speed N
Signals such as E, accelerator position Accp, parking brake PB, etc. are inputted, and the switching control valve is switched in accordance with the driving state determining means for determining the driving state from the values of these signals and the result of the determination by the driving state determining means. The switching control means and the control valve adjusting means are realized on the ECU. The heat exchanger control means for issuing a cooling water heating command by the heat exchanger 84 based on the result of determination by the operating state determination means is also implemented on the ECU 18.

Continuing the description of the combustion type heater 22, the fuel introduction passage 25 is connected to the combustion cylinder 22b so that a part of the fuel discharged from the fuel pump 16 is supplied to the combustion cylinder 22b. Has become. Further, a vaporizing glow plug (not shown) for vaporizing the fuel supplied through the fuel introduction passage 25 is provided in the combustion cylinder 22b.
And an ignition glow plug (not shown) for igniting the vaporized fuel. The vaporizing glow plug and the ignition glow plug may be shared by a single glow plug.

In the combustion type heater 22 configured as described above, the intake air flowing into the air supply port 22e from the heater branch pipe 31 is guided to the combustion chamber 22d, and is supplied to the combustion cylinder 22b through the fuel introduction passage 25. The fuel is vaporized by the vaporizing glow plug. Then, the intake air and the vaporized fuel are mixed to form an air-fuel mixture, and the air-fuel mixture is ignited by an ignition glow plug in the combustion chamber 22d and burns.

The combustion type heater 22 has a combustion gas discharge pipe 51 as a combustion gas discharge path for introducing combustion gas from an exhaust discharge port 22f to an exhaust pipe 14 located downstream or upstream of the catalyst 13. Is provided. Then, the combustion gas from the exhaust outlet 22f is discharged to the downstream side or the upstream side of the catalyst 13.

Next, the EGR control valve 8 according to this embodiment
Control 3 will be described. The control of the flow rate of the combustion gas by the EGR control valve 83 is calculated from an EGR duty map determined from the fuel injection amount and the engine speed as shown in FIG. This is the same as that used for known EGR control. As a result, as shown in FIG.
When GRduty increases, the EVRV 82 opens greatly, the negative pressure applied to the control valve 83 also increases, and the EGR control valve 83 opens greatly, and the flow rate of exhaust gas, that is, EGR%
Becomes larger.

The EGR control valve 83 is opened when the internal combustion engine is in a low or middle speed range such as at low speed or medium speed and the engine temperature rises, and the exhaust gas is supplied from the exhaust system to the intake system through the EGR pipe 81. return. Note that the EGR device does not operate during a high-load operation range or during deceleration. When the EGR control valve 83 is opened during high load operation, the exhaust pressure in the exhaust pipe 14 decreases,
This may cause the rotation of the turbine 6b to decrease or cause black smoke to be generated.

The control of the EGR control valve 83 is realized by the ECU 18 executing a routine as shown in FIG. This control routine is a routine that is repeatedly executed at predetermined time intervals.

First, initialization is performed in S101, and in S102
The engine speed NE, the temperature of the cooling water flowing through the internal combustion engine, and the like are taken into the ECU 18. Next, in S103, the fuel injection amount is taken into the ECU 18. further,
In S104, the control duty ratio of the EVRV 82 is determined from the two-dimensional map determined by the engine speed × the fuel injection amount. When the control duty ratio of the EVRV 82 is determined, the opening degree of the EGR control valve 83 is determined by controlling the EVRV 82 on the basis of the value, and therefore, S10
5, the EGR%, that is, the combustion gas ratio is determined.

When the EGR control should not be performed, the EGR control valve 83 is closed, and the combustion gas from the exhaust outlet 22f is discharged downstream or upstream of the catalyst 13. In this case, if the combustion gas is discharged to the upstream side of the catalyst 13, the combustion gas passes through the catalyst and is discharged from the exhaust pipe 14, so that the catalyst can be activated before the engine is started. NOx purification performance can be improved.

Conventionally, when the engine is started, that is, before warm-up, the cooling water temperature is 20 ° C. to 30 ° C. At such time, if exhaust gas is introduced into the engine, the air-fuel ratio becomes rich and misfire occurs. In general, EGR control is not normally performed.

On the other hand, it is desirable to perform the EGR control even when the cooling water of the internal combustion engine is in a low temperature range in order to reduce the emission. However, when the heat exchanger 84 is a water-cooled cooler using cooling water, EGR control
The exhaust gas flowing through the GR pipe 81 is cooled by a water-cooled cooler to improve the volume efficiency. Even when the engine is started, the cooling water is not warmed, so if the heat exchanger 84 functions as a water-cooled cooler, the exhaust gas will be overcooled. In such a case, and in the case where the temperature of the outside air to be sucked in is low, if the supercooled low-temperature exhaust gas is further introduced, the combustion deteriorates.

Therefore, in this embodiment, the water-cooled cooler is used not as a cooling device but as a heating device, and the exhaust gas introduced by EGR control is heated by the heat exchanger 84, so that deterioration of combustion can be prevented. As a result, EGR control from a low water temperature region becomes possible.

Since the exhaust gas is heated by the heat of the combustion heater 22 through the heat exchanger 84, the warm-up is promoted by introducing the cooling water into the internal combustion engine, and the startability is improved. Further, by switching the cooling water introduced into the heat exchanger 84 by the switching control valve, it is possible to heat and cool the temperature of the exhaust gas flowing through the EGR pipe 84 and to maintain the temperature in a predetermined temperature range, thereby achieving stable operation. EGR control becomes possible.

For this reason, when the operating state determining means on the ECU 18 determines that predetermined conditions are satisfied based on input signals such as the intake air temperature, the engine speed, the cooling water temperature, and the accelerator position, the operating state determining means Upon receiving the signal, an exhaust gas heating command by the heat exchanger is issued from the ECU which is the heat exchanger control means, whereby the exhaust gas returned to the intake system during the EGR control is heated.

The predetermined condition for heating here is when the engine speed is low, EGR control is performed, and when the cooling water temperature is low or, in addition, when the intake air temperature is low. And so on. For heating, it is a condition that the combustion type heater 22 is operating.

When the warming-up of the internal combustion engine has been completed and the temperature of the cooling water has increased, and it is no longer necessary to heat the exhaust gas,
The heating of the cooling water by the combustion type heater 22 is stopped or the cooling water heated by the combustion type heater 22 is not introduced into the heat exchanger 84.

Further, when the internal combustion engine is under a high load, the heat exchanger 84 functions as a water-cooled cooler to cool the exhaust gas in order to lower the temperature of the exhaust gas recirculated by the EGR control and increase the volumetric efficiency. . For this purpose, the operating state determining means determines whether or not the internal combustion engine is under a high load, and if the internal combustion engine is under a high load, sends the cooling water not heated by the combustion type heater 22 to the heat exchanger 84, and During the control, the exhaust gas returned to the intake system is cooled. For this reason, the operation of the combustion type heater 22 is stopped or the switching control valve is switched by the switching control means in accordance with the result of determination by the operating state determination means.

[0056]

According to the present invention, the exhaust gas used in the EGR control can be heated using the heat of the combustion heater. Therefore, even when the cooling water is at a low temperature, it is possible to raise the exhaust gas temperature by the EGR control and prevent deterioration of the combustion, so that the EGR control in the low water temperature region becomes possible, and the reduction of the emission can be promoted. it can.

Further, by introducing the heated exhaust gas into the internal combustion engine at the time of starting the internal combustion engine, for example, warm-up can be promoted, and as a result, the startability can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an internal combustion engine having a combustion heater according to the present invention.

FIG. 2 is a schematic sectional view of a combustion type heater.

FIG. 3 is an EGR duty map determined from a fuel injection amount and an engine speed.

FIG. 4 is a graph showing a relationship between EGR duty and EGR%.

FIG. 5 is a diagram showing a control routine according to the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine body 2 ... Intake device 3 ... Exhaust device 4 ... Heater core 5 ... Air cleaner 6 ... Turbocharger 6a ... Compressor 6b ... Turbocharger turbine 7 ... Intercooler 8 ... Intake manifold 9 ... Intake pipe 11 ... Intake throttle valve 12 ... Exhaust manifold 13 Exhaust purification catalyst 13a NOx catalyst 13b Oxidation catalyst 14 Exhaust pipe 18 ECU 22a Heater internal cooling water passage 22b Combustion cylinder 22c Partition wall 22d Combustion chamber 22e Air supply port 22f Exhaust exhaust port Reference Signs List 24 outer wall 25 fuel introduction passage 31 heater branch pipe 32 cooling water introduction passage 33 cooling water discharge passage 41 vacuum pump 42 electric vacuum regulating valve (EVRV) 43 actuator 51 combustion gas discharge pipe 81 ... E R pipes 82 ... Electric vacuum regulating valve (EVRV) 83 ... EGR control valve 84 ... heat exchanger

Claims (5)

[Claims] An internal combustion engine having an intake system for introducing fresh air into an engine and an exhaust system for discharging exhaust gas generated by combustion of fuel in the engine, and for discharging exhaust gas discharged from the exhaust system. An internal combustion engine having an exhaust recirculation passage returning to the intake system by bypassing, and further having a combustion type heater provided to raise the temperature of the engine-related elements by heat obtained by burning fuel. In the middle of the exhaust gas recirculation passage, there is provided a heat exchanger for exchanging heat with the exhaust gas flowing in the exhaust gas recirculation passage, and the combustion type heater is connected to the heat exchanger as a heat source to operate the internal combustion engine. An internal combustion engine having a combustion type heater, wherein an exhaust gas flowing in an exhaust gas recirculation passage is heated by a heat exchanger according to a state. 2. A combustion type heater according to claim 1, further comprising heat exchanger control means for judging an operation state of the internal combustion engine and issuing an exhaust gas heating command by the heat exchanger according to the operation state. An internal combustion engine having: 3. The internal combustion engine having a combustion heater according to claim 1, wherein the heat exchanger also serves as a cooling unit for cooling exhaust gas passing through the exhaust gas recirculation passage. 4. An internal combustion engine having a combustion-type heater according to claim 3, wherein the temperature of the exhaust gas flowing through the exhaust gas recirculation passage is controlled to a predetermined temperature range by heating or cooling by the heat exchanger. . 5. A first cooling water introduction passage for introducing cooling water heated by a combustion type heater into a heat exchanger, and a second cooling water introducing cooling water not heated by a combustion type heater to a heat exchanger. 5. The combustion type heater according to claim 3, further comprising an introduction path, and switching means for switching between the first cooling water passage and the second cooling water passage according to an operation state of the internal combustion engine. Having an internal combustion engine.