JP2002070663A - Internal combustion engine having a combustion heater - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide a technique for preventing a liquid such as condensed water from staying in an intake passage before starting an internal combustion engine in an internal combustion engine having a combustion heater. And An internal combustion engine having a combustion heater according to the present invention includes a combustion heater having a combustion chamber independent of the internal combustion engine, and a combustion gas of the combustion heater or a medium heated by the combustion heater. A first passage leading to an intake passage, a second passage leading combustion gas of a combustion heater or a medium heated by the combustion heater to an exhaust passage of the internal combustion engine, and stopping operation of the internal combustion engine when the combustion heater is operated Path switching means for closing the first path and opening the second path when in the state.

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 mounted on a vehicle or the like, and more particularly, to an internal combustion engine having a combustion type heater for heating an internal combustion engine or heating air via a predetermined medium.

[0002]

2. Description of the Related Art In recent years, in an internal combustion engine mounted on an automobile or the like, particularly an internal combustion engine whose heat generation is relatively small, such as a compression ignition type diesel engine, the performance of an indoor heating device when the engine is cold is improved. For the purpose of promoting warm-up of an internal combustion engine and the like, a technique in which a combustion type heater is additionally provided is proposed.

[0003] As the above-mentioned combustion type heater, for example, a heat exchange section comprising a combustion chamber independent of an internal combustion engine, and a heat medium passage formed so as to surround the combustion chamber;
An intake passage for supplying combustion air to the combustion chamber,
2. Description of the Related Art There is known a fuel supply system that includes a fuel supply passage that supplies a part of fuel of an internal combustion engine to a combustion chamber.

In the combustion type heater configured as described above,
As the heat medium, engine cooling water or air for heating can be used.

When the engine cooling water is used as a heat medium, the cooling water heated by the combustion type heater is supplied to the water jacket of the internal combustion engine when the internal combustion engine is cold to warm up the internal combustion engine. Can be promoted, and the heating performance can be improved by supplying the cooling water heated by the combustion heater to the heater core of the indoor heating device.

When heating air is used as a heat medium, heating air heated by a combustion type heater is supplied into the vehicle cabin so that even when the internal combustion engine is in a cold state. Heating performance can be improved.

Further, when the internal combustion engine is cold started,
By supplying high-temperature combustion gas discharged from the combustion heater or heating air heated by the combustion heater to the intake passage of the internal combustion engine, the intake temperature of the internal combustion engine is increased,
Thus, it is conceivable to improve the startability of the internal combustion engine.

[0008] For example, an intake air heating device for an internal combustion engine of a vehicle described in Japanese Patent Application Laid-Open No. Sho 60-79149 uses heating air heated by a combustion type heater to heat a vehicle room heating device and intake air of the internal combustion engine. The heating air heated by the combustion type heater is supplied to the intake passage of the internal combustion engine when the internal combustion engine is started or when the engine is cold, for example. The supply is intended to increase the intake air temperature of the internal combustion engine, thereby improving the startability and the warm-up property.

[0009]

In the case where the temperature of the intake air of the internal combustion engine is increased by using high-temperature combustion gas discharged from the combustion heater or heating air heated by the combustion heater, the temperature of the internal combustion engine is increased. Is in an operation stop state, when the high-temperature combustion gas or the heating air is supplied into the low-temperature intake passage, the gas such as the steam in the combustion gas or the heating air is liquefied to form condensed water, and the condensed water is condensed. Water may stay in the intake passage.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in an internal combustion engine having a combustion heater, it is intended that liquid such as condensed water stays in an intake passage before the internal combustion engine is started. The aim is to provide technology to prevent it.

[0011]

The present invention employs the following means in order to solve the above-mentioned problems.

That is, an internal combustion engine having a combustion heater according to the present invention includes a combustion heater having a combustion chamber independent of the internal combustion engine, and a combustion gas of the combustion heater or a medium heated by the combustion heater. A first passage leading to an intake passage of the internal combustion engine, a second passage leading a combustion gas of the combustion heater or a medium heated by the combustion heater to an exhaust passage of the internal combustion engine, and the combustion heater And a passage switching means for closing the first passage and opening the second passage when the internal combustion engine is in an operation stop state during the operation.

In the internal combustion engine having the combustion heater configured as described above, when the combustion heater is operated, if the internal combustion engine is in an operation stop state, the first passage is closed and the second passage is closed. The passage is opened.

In this case, the combustion gas of the combustion heater or the medium heated by the combustion heater flows through the second passage and is guided to the exhaust passage of the internal combustion engine. As a result, when the operation of the internal combustion engine is stopped, the high-temperature combustion gas or medium does not flow into the low-temperature intake passage, and gas such as steam contained in the combustion gas or medium is liquefied in the intake passage. There is no stagnation.

Further, when the combustion type heater is operated and the internal combustion engine is in an operation stop state, it is necessary to preheat the internal combustion engine or to heat air for indoor heating when the internal combustion engine is cold. For example. At this time, the passage switching means closes the first passage and opens the second passage until the internal combustion engine is started, and opens and closes the first passage after the internal combustion engine is started. Preferably, the second passage is closed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of an internal combustion engine having a combustion heater according to the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing one embodiment of an internal combustion engine having a combustion type heater.

The internal combustion engine 1 shown in FIG. 1 is a water-cooled direct injection type diesel engine having a plurality of cylinders and a fuel injection valve for directly injecting fuel into a combustion chamber of each cylinder.

An intake branch pipe 2 is connected to the internal combustion engine 1.
Each branch pipe of the intake branch pipe 2 communicates with a combustion chamber of each cylinder via an intake port (not shown). The intake branch pipe 2 is
The intake pipe 3 is connected to an air cleaner box 4 in which an air filter is provided.

In the middle of the intake pipe 3, a compressor housing 5a of a centrifugal supercharger (turbocharger) 5 is provided. A compressor wheel (not shown) is rotatably supported in the compressor housing 5a. The rotary shaft of the compressor wheel is connected to a rotary shaft of a turbine wheel rotatably supported in a turbine housing 5b described later, so that the compressor wheel and the turbine wheel rotate integrally.

Subsequently, the compressor housing 5a
The downstream intake pipe 3 is provided with an intercooler 6 that cools intake air that has become hot when compressed by the compressor housing 5a. The intake pipe 3 downstream of the intercooler 6 is provided with an intake throttle valve 7 for adjusting the intake flow rate in the intake pipe 3. The intake throttle valve 7 has an actuator 8 for opening and closing the intake throttle valve 7. Installed.

In the intake system configured as described above, fresh air flowing into the air cleaner box 4 is filtered by an air filter to remove dust and dirt, and then guided to the compressor housing 5a through the intake pipe 3, and the compressor housing 5a Compressed within. The fresh air that has been compressed in the compressor housing 5 a and has become high temperature is cooled by the intercooler 6. The intake air cooled by the intercooler 6 is adjusted in its flow rate by an intake throttle valve 7 as required, then distributed to the combustion chamber of each cylinder via the intake branch pipe 2, and injected from a fuel injection valve (not shown). It is burned using fuel as an ignition source.

On the other hand, an exhaust branch 9 is connected to the internal combustion engine 1, and each branch of the exhaust branch 9 communicates with a combustion chamber of each cylinder via an exhaust port (not shown). The exhaust branch pipe 9 is connected to an exhaust pipe 10, and the exhaust pipe 10 is connected downstream to a muffler (not shown).

An exhaust gas purifying catalyst 11 for purifying harmful gas components in exhaust gas is disposed in the exhaust pipe 10. Examples of the exhaust purification catalyst 11 include a selective reduction type lean NO _X catalyst, a storage reduction type lean NO _X catalyst, a particulate filter carrying an oxidation catalyst, and the like.

The exhaust pipe 10 upstream of the exhaust purification catalyst 11 is provided with a turbine housing 5b containing a turbine wheel that rotates by the pressure of exhaust gas. In the exhaust pipe 10 (or the exhaust branch pipe 9) upstream of the turbine housing 5b, a part of the exhaust flowing through the exhaust pipe 10 is supplied to the intake pipe 3 (or the intake branch pipe 2) downstream of the intake throttle valve 7.
An exhaust gas recirculation passage (EGR passage) 12 leading to the
An EGR valve 13 for adjusting the amount of exhaust gas recirculation is provided in the EGR passage 12.

In the exhaust system configured as above, the air-fuel mixture burned in the combustion chamber of each cylinder is guided to the exhaust pipe 10 through each branch pipe of the exhaust branch pipe 9, and then to the turbine housing 5.
b. The exhaust gas flowing into the turbine housing 5b is discharged from the turbine housing 5b after rotating the turbine wheel, and flows into the exhaust purification catalyst 11 through the exhaust pipe 10 downstream of the turbine housing 5b.
At this time, if the catalyst bed temperature of the exhaust purification catalyst 11 is equal to or higher than the activation temperature, the exhaust purification catalyst 11 purifies harmful gas components in the exhaust gas.

When the EGR valve 13 is open, a part of the exhaust gas flowing through the exhaust pipe 10 is guided to the intake pipe 3 through the EGR passage 12 and the new exhaust gas flowing from the upstream of the intake pipe 3. The mixture is guided to the combustion chamber of the internal combustion engine 1 while being mixed with the air, and is reburned using the fuel injected from a fuel injection valve (not shown) as an ignition source.

Next, the combustion type heater 14
Is attached. As shown in FIG. 2, the combustion type heater 14 includes an outer cylinder 140 and an intermediate cylinder 1 provided inside the outer cylinder 140.
41, and a combustion cylinder 142 which is provided in the intermediate cylinder 141 and burns fuel for the internal combustion engine 1 independently of the internal combustion engine 1.

The combustion cylinder 142 has a vaporizing glow plug (not shown) for vaporizing fuel and an ignition glow plug (not shown) for igniting the fuel vaporized by the vaporizing glow plug. are doing. The vaporizing glow plug and the ignition glow plug may be shared by a single glow plug.

Subsequently, the outer cylinder 140 and the intermediate cylinder 14
1, a cooling water passage 200 in the heater for flowing the cooling water of the internal combustion engine 1 is formed. The outer cylinder 140 has a cooling water introduction port 143 for taking in cooling water into the cooling water passage 200 in the heater, and a cooling water discharge port 144 for discharging cooling water in the cooling water passage 200 in the heater. Is formed.

As shown in FIG. 1, the cooling water introduction port 143 communicates with a water jacket (not shown) of the internal combustion engine 1 through a cooling water introduction pipe 22, and the cooling water discharge port 144 communicates with the water jacket. It communicates via a cooling water discharge pipe 23.

An electric water pump 24 is provided in the middle of the cooling water introduction pipe 22 so that the cooling water flowing in the water jacket of the internal combustion engine 1 is forcibly fed into the cooling water introduction port 143. Has become.

In the middle of the cooling water discharge pipe 23, a heater core 25 of an indoor heating device is arranged so that heat of the cooling water flowing through the cooling water discharge pipe 23 is transmitted to the heating air. I have.

Next, a combustion gas passage 201 for flowing the combustion gas generated in the combustion cylinder 142 is formed between the intermediate cylinder 141 and the combustion cylinder 142. A combustion gas discharge port 145 for communicating the combustion gas passage 201 with the outside of the outer cylinder 140 is formed at an appropriate position of the intermediate cylinder 141.

As shown in FIG. 1, the combustion gas discharge port 145 communicates with a three-way switching valve 17 via a combustion gas discharge passage 16. The three-way switching valve 17 has an intake-side exhaust passage 1 in addition to the first combustion gas exhaust passage 16.
8 and the exhaust side discharge passage 19 are connected.

The intake side exhaust passage 18 is connected to the intake pipe 3 upstream of the intake throttle valve 7 and is connected to the exhaust side exhaust passage 1.
9 is connected to an exhaust pipe 10 located between the exhaust purification catalyst 11 and the turbine housing 5b, preferably an exhaust pipe 10 near the exhaust purification catalyst 11.

The three-way switching valve 17 selectively closes one of the intake-side exhaust passage 18 and the exhaust-side exhaust passage 19 so that the first combustion gas exhaust passage 16 and the intake-side exhaust passage 18 are closed. The discharge passage 18 is electrically connected (the exhaust-side discharge passage 19 is closed) and the first combustion gas discharge passage 16 is closed.
And the conduction of the exhaust-side discharge passage 19 (the closing of the intake-side discharge passage 18).

Next, the fuel introduction pipe 27 is
Is connected. The fuel introduction pipe 27 is connected to the fuel pump 26 as shown in FIG.
The fuel discharged from 6 is supplied to the combustion cylinder 142 through the fuel introduction pipe 27.

On the other hand, the outer cylinder 140 is provided with the combustion cylinder 1
Blower fan 149 for sending air for combustion to
And a motor 150 for rotationally driving the blower fan 149.
Is mounted.

The housing 148 has an intake port 15 for taking combustion air into the housing 148.
1 is formed. As shown in FIG.
As shown in FIG. 5, the intake passage 15 is connected, and the intake passage 15 is located in the intake pipe 3 at a position upstream of a connection with the intake-side discharge passage 18 and downstream of the compressor housing 5a. It is connected to the.

In the combustion type heater 14 configured as described above, for example, it is necessary to preheat the internal combustion engine 1 and promote warm-up, improve the performance of the indoor heating device, or increase the temperature of the exhaust purification catalyst 11. Activated if

More specifically, in the combustion type heater 14, the motor 150 operates the blower fan 149 to supply a part of the intake air flowing through the intake pipe 3 to the combustion cylinder 142 of the combustion type heater 14, and the fuel pump 26 Sucks up the fuel in a fuel tank (not shown) and supplies it to the combustion cylinder 142 of the combustion type heater 14, and further operates the water pump 24 to introduce the cooling water in the water jacket of the internal combustion engine 1 into the cooling water of the combustion type heater 14. Feed to port 143.

Then, the glow plug of the combustion cylinder 142 is energized, and a mixture of the intake air supplied by the blower fan 149 and the fuel supplied by the fuel pump 26 is burned in the combustion cylinder 145.

The combustion gas burned in the combustion cylinder 145 is pushed out of the combustion cylinder 145 to the combustion gas passage 201 by the pressure of the intake air sent out by the blower fan 149, and then from the combustion gas passage 201 to the combustion gas discharge port 145. Is discharged to

The combustion gas discharged to the combustion gas discharge port 145 passes through the combustion gas discharge passage 16 and the three-way switching valve 1
7 and is guided to the intake side exhaust passage 18 or the exhaust side exhaust passage 19 by the three-way switching valve 17.

On the other hand, the cooling water pressure-fed to the cooling water introduction port 143 of the combustion type heater 14 by the water pump 24 is guided from the cooling water introduction port 143 to the cooling water passage 200 in the heater, and passes through the cooling water passage 200 in the heater. After that, it is discharged to the cooling water discharge port 144.

At this time, the heat of the combustion gas flowing in the combustion gas passage 201 is transmitted to the cooling water flowing in the cooling water passage 200 in the heater via the wall surface of the intermediate cylinder 144, and the temperature of the cooling water rises. Thus, the cooling water passage 200 in the heater and the combustion gas passage 201 implement a heat exchange unit.

The cooling water thus heated is discharged from the cooling water discharge port 144 to the cooling water discharge pipe 23,
It is returned to the water jacket of the internal combustion engine 1 via the heater core 25 and circulates in the water jacket. In the heater core 25, part of the heat of the cooling water is transmitted to the air for heating, and the temperature of the air for heating is raised.

Returning to FIG. 1, the internal combustion engine 1 includes an electronic control unit (ECU) for controlling the engine.
ol Unit) 28 is also provided. The ECU 28 includes a CPU, a ROM,
It comprises a RAM, an input interface circuit, an output interface circuit and the like. Various sensors are connected to the input interface circuit via electric wiring, and the output interface circuit includes an EGR valve 13,
Actuator 8, combustion type heater 14 (blowing fan 14
9, the motor 150, the glow plug of the combustion cylinder 142), the three-way switching valve 17, the water pump 24, the fuel pump 26, and the like are connected via electric wiring.

The sensors connected to the input interface circuit include an air flow meter 29 attached to the intake pipe 3, a crank position sensor 30 and a water temperature sensor 31 attached to the internal combustion engine 1, and an exhaust purification catalyst 1.
1, a catalyst temperature sensor 32 attached to an accelerator pedal (not shown), an accelerator position sensor 33 attached to an accelerator lever or the like that operates in conjunction with the accelerator pedal, and an ignition switch (IG. SW) 3
4, a starter switch (ST. SW) 35 and the like can be exemplified.

The air flow meter 29 is a sensor that outputs an electric signal corresponding to the mass of intake air flowing through the intake pipe 3. The crank position sensor 30 is a sensor that outputs a pulse signal every time a crankshaft (not shown) of the internal combustion engine 1 rotates by a predetermined angle. The water temperature sensor 31 is a sensor that outputs an electric signal corresponding to the temperature of the cooling water flowing through the water jacket of the internal combustion engine 1. The catalyst temperature sensor 32 is a sensor that outputs an electric signal corresponding to the catalyst bed temperature of the exhaust purification catalyst 11. The accelerator position sensor 33 is a sensor that outputs an electric signal corresponding to the operation amount of the accelerator pedal.

The ECU 28 determines the operating state of the internal combustion engine 1 based on the output signal values of the various sensors as described above, executes fuel injection control and the like based on the determination result, and forms the gist of the present invention. The combustion heater control is performed.

Hereinafter, the combustion type heater control executed by the ECU 28 will be described.

The ECU 28 operates as shown in FIG.
The combustion type heater control routine shown in FIG. This combustion type heater control routine is executed at predetermined time intervals (for example,
This is a routine that is repeatedly executed each time the crank position sensor 30 outputs a pulse signal.

In the combustion type heater control routine,
The ECU 28 first determines in S301 whether the operating condition of the combustion heater 14 is satisfied. The operating conditions of the combustion type heater 14 here include, for example, the output signal value of the catalyst temperature sensor 32 (the catalyst bed temperature of the exhaust purification catalyst 11).
There is less than the activation temperature, a SO _x poisoning recovery processing execution timing of the exhaust purification catalyst 11, an NO _X reduction process execution time when the exhaust purification catalyst 11 is storage reduction NO _X catalyst, the indoor heating Water temperature sensor 31 with device in operation
Is lower than the predetermined temperature (that is, the internal combustion engine 1 is in a cold state).

If it is determined in S301 that the operating condition of the combustion type heater is satisfied, the ECU 28 proceeds to S301.
Proceeding to 302, it is determined whether the internal combustion engine 1 is in an operation stop state.

If it is determined in step S302 that the internal combustion engine 1 is in the operation stop state, the ECU 28 proceeds to step S3.
In step 03, the three-way switching valve 17 is controlled so as to close the intake-side exhaust passage 18 and open the exhaust-side exhaust passage 19, thereby making the combustion gas exhaust passage 16 and the exhaust-side exhaust passage 19 conductive.

Subsequently, the ECU 28 determines in S304 that the motor 150, the fuel pump 26, and the combustion cylinder 142
Drive power is applied to the glow plug of
Activate

In this case, the combustion gas discharged from the combustion type heater 14 is supplied to the combustion gas discharge passage 16 → the three-way switching valve 17.
→ It is guided to the exhaust pipe 10 upstream of the exhaust purification catalyst 11 through the exhaust side discharge passage 19 in order.

As a result, when the internal combustion engine 1 is in an operation stop state, the high-temperature combustion gas discharged from the combustion heater 14 is not supplied into the low-temperature intake pipe 3 but is contained in the combustion gas. Gases such as water vapor are not liquefied and stay in the intake pipe 3.

If it is determined in S302 that the internal combustion engine 1 is already operating, the ECU 28
Open the exhaust side exhaust passage 18 and exhaust side exhaust passage 1
The three-way switching valve 17 is controlled to close the valve 9, and the combustion gas discharge passage 16 and the intake-side discharge passage 18 are connected.

Subsequently, the ECU 28 determines in S304 that the motor 150, the fuel pump 26, and the combustion cylinder 142
Drive power is applied to the glow plug of
Activate

In this case, the combustion gas discharged from the combustion type heater 14 is supplied to the combustion gas discharge passage 16 → the three-way switching valve 17
→ The air is sequentially guided to the intake pipe 3 through the intake-side discharge passage 18.

As a result, when the internal combustion engine 1 is in the operating state, the high-temperature combustion gas discharged from the combustion heater 14 is supplied into the intake pipe 3, so that the heat of the combustion gas causes the temperature of the intake air to rise. The temperature of the air-fuel mixture and the compression end temperature in the combustion chamber are increased, so that the ignitability and combustion stability of the internal combustion engine 1 are improved.

On the other hand, if it is determined in S301 that the operating condition of the combustion type heater 14 is not satisfied, the ECU 28 stops applying the driving power to the motor 150, the fuel pump 26, and the glow plug of the combustion cylinder 142. Then, the operation of the combustion type heater 14 is stopped.

As described above, when the ECU 28 executes the combustion type heater control routine, the passage switching means according to the present invention is realized.

Therefore, according to the internal combustion engine having the combustion type heater according to the present embodiment, if the operation request of the combustion type heater 14 is generated before the internal combustion engine 1 is cold started, the combustion type heater 14 is discharged. Since the burned combustion gas is led to the exhaust pipe 10, the high-temperature combustion gas discharged from the combustion heater 14 does not flow into the low-temperature intake pipe 3.

As a result, when the high-temperature combustion gas flows into the low-temperature intake pipe 3, the water vapor in the combustion gas does not become condensed water and stay in the intake pipe 3.

In the present embodiment, the combustion type heater using engine cooling water as a medium has been described as an example. However, a combustion type heater using a medium such as air for heating may be used. Further, in the present embodiment, an example has been described in which the combustion gas of the combustion heater is selectively discharged to one of the intake passage and the exhaust passage of the internal combustion engine. A combustion type heater that can selectively supply either one of the intake passage and the exhaust passage may be used. What is necessary is just to supply it to an exhaust passage.

[0070]

In the internal combustion engine having the combustion heater according to the present invention, if the operation of the combustion heater is stopped when the internal combustion engine is stopped, the first passage is closed and the second passage is closed.
Is opened, the combustion gas of the combustion heater or the medium heated by the combustion heater is led to the exhaust passage of the internal combustion engine, and when the operation of the internal combustion engine is stopped, high-temperature combustion is performed. Gas or medium does not flow into the cold intake passage.

Therefore, according to the internal combustion engine having the combustion type heater according to the present invention, when the operation of the internal combustion engine is stopped, the gas such as the combustion gas of the combustion type heater or the vapor contained in the medium is condensed with the condensed water in the intake passage. It is possible to prevent stagnation.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of an internal combustion engine with a combustion heater according to the present invention.

FIG. 2 is a diagram showing an internal configuration of a combustion heater.

FIG. 3 is a flowchart showing a combustion type heater control routine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Intake branch pipe 3 ... Intake pipe 5 ... Centrifugal supercharger 9 ... Exhaust branch pipe 10 ... Exhaust pipe 11 ... Exhaust purification catalyst 14 ... Combustion type Heater 15. Intake intake passage 16. Combustion gas exhaust passage 17. Three-way switching valve 18. Intake side exhaust passage 19. Exhaust side exhaust passage 22. Cooling water introduction pipe 23. Cooling water exhaust pipe 25.・ Heater core 26 ・ ・ Fuel pump 27 ・ ・ Fuel supply pipe 28 ・ ・ ECU

Claims (2)

[Claims] 1. A combustion heater having a combustion chamber independent of an internal combustion engine, and a first gas for guiding a combustion gas of the combustion heater or a medium heated by the combustion heater to an intake passage of the internal combustion engine.
A second passage for guiding a combustion gas of the combustion heater or a medium heated by the combustion heater to an exhaust passage of the internal combustion engine.
And a passage switching means for closing the first passage and opening the second passage when the internal combustion engine is in an operation stop state at the time of operation of the combustion heater. An internal combustion engine having: 2. The passage switching means, if an operation request of the combustion type heater is generated before the internal combustion engine is cold started, closes the first passage until the internal combustion engine is started. The internal combustion engine having a combustion heater according to claim 1, wherein the second passage is opened, and after the internal combustion engine is started, the first passage is opened and the second passage is closed. .