JP3528645B2 - 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.

[0002]

2. Description of the Related Art In an internal combustion engine, it is necessary to improve startability and warm up, especially in cold weather.

Therefore, for example, in Japanese Patent Laid-Open No. 62-75069, a combustion type heater is provided in the intake passage of an internal combustion engine,
It shows a technique of supplying combustion gas emitted from a combustion heater to a cylinder via the intake passage. Putting the combustion gas emitted from the combustion heater into the cylinder means taking in the combustion gas as intake air. Since the combustion gas is also exhaust gas, putting the combustion gas, which is exhaust gas, in the cylinder means that the amount of fresh air in the intake air of the internal combustion engine decreases, that is, the amount of oxygen supplied to the cylinder decreases. become. Therefore, it is not preferable to put the combustion gas into the cylinder from the viewpoint of combustibility.

[0004]

On the other hand, an internal combustion engine provided with a turbocharger which is a supercharger, that is, a so-called turbo engine is known, and even in this turbo engine, improvement of startability and promotion of warm-up are promoted. In order to achieve this, it is possible to apply the technique of putting the combustion gas of the combustion heater into the cylinder. Even in that case, the combustibility problem may occur.
In addition, in an engine focused on producing a high output, such as a turbo engine, when the output is high, in other words, when it is necessary to maximize the engine performance, the combustion gas of the combustion heater is used as a cylinder. When it enters, the engine performance is deteriorated as described above. Therefore, driving feeling and drivability may be deteriorated.

The present invention has been made under such a technical background, and in an internal combustion engine for improving startability and warming up by putting combustion gas of a combustion heater into a cylinder, at least at high output. It is an object of the present invention to prevent deterioration of flammability in

[0006]

In order to solve the above problems, an internal combustion engine having a combustion heater according to the present invention employs the following means.

That is, a combustion type heater for raising the temperature of elements related to the engine by the heat obtained by burning the fuel, and a combustion gas discharge passage for discharging the combustion gas of the combustion type heater to the intake passage of the internal combustion engine, A combustion gas introduction passage for introducing the combustion gas flowing through the combustion gas discharge passage into the exhaust passage of the internal combustion engine without passing through the cylinder, and a passage for selectively switching one of the combustion gas introduction passage and the combustion gas discharge passage. A switching valve for opening and a high output request determination means for determining whether or not the internal combustion engine requires high output when the internal combustion engine is operating, and the internal combustion engine is required to output high output. Is determined by the high output request determination means, the switching valve is switched to open the combustion gas introduction passage, thereby leading the combustion gas of the combustion heater to the exhaust passage. An internal combustion engine having a motor.

Here, it is desirable that the "combustion gas introduction passage" is a bypass passage that connects the intake system and the exhaust system to bypass the engine body. However, even though they are the same in terms of a bypass passage that connects the intake system and the exhaust system to bypass the engine body, exhaust gas recirculation that returns exhaust gas from the exhaust system to the intake system during operation of the internal combustion engine for the purpose of reducing NOx. The device (hereinafter referred to as "EGR device") is not included. This is because the EGR device operates for the purpose of reducing NOx in the medium and low load range when the engine is operating, and the exhaust gas flows through the EGR passage which is the main constituent member of the EGR device and which actually connects the intake system and the exhaust system.

The "high output demand determination means" is a computer, that is, a central processing control unit (hereinafter "CP") which is a component of an engine control unit (hereinafter "ECU").
U ”. ). The CPU determines whether or not the internal combustion engine is currently required to have a high output, based on detection values detected by various sensors provided in the internal combustion engine for each engine operating state.

In the internal combustion engine having the combustion heater according to the present invention, when the CPU, which is the high output request determining means, determines that the internal combustion engine is required to have a high output, the combustion gas introduction passage or the combustion gas discharge passage is determined. The combustion gas introduction passage is opened by the switching valve that selectively switches either one. Therefore, if the combustion heater is operating at this time, the combustion gas guides the combustion gas to the exhaust passage through the combustion gas introduction passage. The combustion gas introduction passage is a passage for introducing the combustion gas of the combustion type heater into the exhaust passage of the internal combustion engine without passing through the cylinder as described above. Therefore, the combustion gas does not enter the cylinder when the internal combustion engine has a high output. In the present invention, since the combustion gas does not enter the cylinder, the amount of oxygen occupying the intake air increases accordingly. Therefore, as compared with the conventional technique in which the combustion gas is introduced into the cylinder at the time of high output, the combustibility is not deteriorated and the combustibility is improved.

As a further preferable means, the internal combustion engine has a supercharger for supercharging intake air in the intake passage, and when the supercharger supercharges the intake passage, the switching valve is switched to perform the combustion. The gas introduction passage may be opened. Supercharging refers to a case where the internal combustion engine is rotating at a high speed, a case where the engine is accelerated, or the like, where the engine load is large, and the intake passage is higher than atmospheric pressure. Therefore, the non-supercharging state is the other case, for example, the case where the engine is in the middle and low load range.

Therefore, since the internal combustion engine is required to have a high output during supercharging, the same operational effects as described above are obtained. Further, the switching valve may be operated by receiving a supercharging pressure generated in the intake passage. If the switching valve operates by supercharging pressure, a special mechanism for operating the switching valve becomes unnecessary. Therefore, the apparatus can be downsized and the cost can be reduced.

[0013]

DETAILED DESCRIPTION OF THE INVENTION An internal combustion engine having a combustion heater according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

A diesel engine I as an internal combustion engine to which the present invention is applied has a cylinder 2, an intake device 3 for sending air required for combustion into the cylinder 2, and a cylinder 2.
An exhaust device 4 for discharging exhaust gas emitted from the exhaust gas to the atmosphere.

The cylinder 2 has a cylinder head 2a mounted and fixed on the upper portion thereof. Further, a piston 5 is provided inside the cylinder so as to be vertically movable. A combustion chamber 6 is formed in the piston head that constitutes the upper part of the piston 5.

Further, the cylinder head 2a is provided with an intake port 8 and an exhaust port 9 which face the combustion chamber 6 when the piston 5 rises. An intake valve 8a and an exhaust valve 9a are incorporated in the intake port 8 and the exhaust port 9, respectively. An injector 10 for injecting fuel into the cylinder 2 is arranged between both valves so as to face the cylinder 2.

The injector 10 receives the pump pressure of an injection pump (not shown) and ejects fuel. An intake passage 11 is connected to the intake port 8 and an exhaust passage 12 is connected to the exhaust port 9.

The intake device 3 has an air cleaner (not shown) for filtering the outside air entering the engine I as a starting end and an intake port 8 as an ending end. And air cleaner and intake port 8
A plurality of intake system structures, that is, a compressor 15 of a turbocharger, that is, a turbocharger, is provided on an intake passage 11 between
a, a combustion heater 17 for raising the temperature of engine-related elements such as engine cooling water by the heat obtained by burning the fuel, an intercooler (not shown) which is an intake cooling device, an intake manifold which is an intake branch pipe, etc. are arranged. There is.

The exhaust device 4 has an exhaust port 9 as a starting end and a muffler (not shown) as an ending end. Then, on the exhaust passage 12 between the exhaust port 9 and the muffler, a plurality of exhaust system structures such as a turbine 15b of a turbocharger and a catalytic converter 19 as a gas purifying device are arranged.
The catalytic converter 19 mainly purifies the exhaust gas of the engine I and also purifies the combustion gas of the combustion heater 17. The catalytic converter 19 contains a catalyst (not shown) therein. The catalyst is activated when it reaches a predetermined temperature, thereby purifying exhaust gas and the like.

The intake device 3 and the exhaust device 4 are connected by two connecting pipes connecting the two separately, that is, the combustion gas introduction passage 21 and the EGR device 23. For more information,
The combustion gas introduction passage 21 is a bypass passage that bypasses the engine body (strictly speaking, the cylinder 2). Therefore, the combustion gas of the combustion heater 17 is the combustion gas introduction passage 2
When it goes through 1, it is introduced from the intake system to the exhaust system without passing through the engine body.

The EGR device 23 is a device for returning the exhaust gas emitted from the exhaust port 9 to the intake system, and thereby reduces the nitrogen oxides generated in the cylinder 2. The EGR device 23 includes an EGR passage 23a as an exhaust gas recirculation passage that connects the intake device 3 and the exhaust device 4, and an EGR passage 23a.
And an EGR valve 23b for adjusting the amount of exhaust gas passing through. The EGR valve 23b opens when the engine temperature rises when the engine I is in a medium or low load range such as when the engine I is low speed or medium speed (hereinafter referred to as "normal running"), and at this time, through the EGR passage 23a. Return exhaust gas from the exhaust system to the intake system. The EGR device 23 does not operate during idling and at high speed. This is because the engine temperature is low during idling and the NOx reduction effect is small. Also, if the EGR passage 23a is opened at a high speed, the exhaust pressure in the exhaust passage 12 is reduced, and the rotation of the turbine 15b is reduced.

On the other hand, the combustion type heater 1 belonging to the intake device 3
Reference numeral 7 denotes an air supply passage 33 for supplying air from the intake passage 11 to the combustion heater 17, and a combustion gas supplied from the air supply passage 33. And a combustion gas discharge passage 35 that discharges into the intake passage 11. The combustion heater 17 is connected to the intake passage 11 by the air supply passage 33 and the combustion gas discharge passage 35. Further, the combustion heater 17 has a blower fan 17 a for adjusting the amount of air flowing through an air flow passage (not shown) of the combustion heater 17.

In addition, the air supply passage 33 of the intake passage 11
And between the connection point C1 of the intake passage 11 and the connection point C2 of the combustion gas discharge passage 35 and the intake passage 11,
An intake throttle valve 38 that throttles intake air passing through the intake passage 11 is provided.

A three-way valve 36 is provided in the middle of the combustion gas discharge passage 35. One end of the combustion gas introduction passage 21 is connected to the three-way valve 36, and the other end of the combustion gas introduction passage 21 is connected to the catalytic converter 19 in the exhaust passage 12.
Is connected to the upstream vicinity C3. Also, three-way valve 3
The compressor 6 is connected to the compressor 15a so that the compressor 6 operates by receiving supercharging pressure. .

As shown in FIG. 1, during supercharging, that is, when the engine I has a high output, the three-way valve 36 is switched to open the combustion gas introduction passage 21. By opening the combustion gas introduction passage 21, the combustion gas of the combustion heater 17 flows toward the location C3 of the exhaust passage 12 via a part of the combustion gas discharge passage 35 and the combustion gas introduction passage 21. . Since the location C3 is located upstream of the catalytic converter 19 in the vicinity, the combustion gas reaching the location C3 is then transferred to the catalytic converter 1
9 is entered and the catalyst is activated soon.

Further, during supercharging, the combustion gas introducing passage 21
Is opened by the three-way valve 36, the intake throttle valve 38
To open the intake passage 11. However, at this time, E
The GR valve 23b is closed. During supercharging, EGR valve 2
This is to prevent this because the rotational force of the turbine is weakened and the output is reduced if 3b is opened.

Then, in the case of supercharging, the combustion gas flows through the combustion gas introduction passage 21, that is, the combustion gas does not pass through the cylinder 2 and flows to a portion C3 near the upstream side of the catalytic converter 19. That is, since the combustion gas discharge passage 35 is closed, the combustion gas of the combustion heater 17 does not flow into the intake passage 11. Therefore, the combustion heater 1 is installed in the cylinder 2.
Only the outside air that is directly introduced from the intake passage 11 does not flow, and does not include the combustion gas emitted by the fuel cell 7.

As shown in FIG. 2, in the case of no supercharging, the three-way valve 36 closes the combustion gas introducing passage 21. On the contrary, the combustion gas discharge passage 35 is opened. Therefore, in this case, the combustion gas flows through the combustion gas discharge passage 3 as shown by the solid arrow in FIG.
5 to the intake passage 11 and then the cylinder 2
Once inside, it acts as a warm-up engine. At this time, the intake throttle valve 38 remains open. Therefore, the intake air directed to the cylinder 2 is a mixture of combustion gas and outside air.

Further, if the engine temperature rises during normal running without supercharging, the EGR valve 23b is opened. Therefore,
The EGR device 23 operates. Then, in this case, the exhaust gas is recirculated from the exhaust side to the intake side as indicated by the dashed arrow in FIG. In this case, since it is not during supercharging, the turbine 15b is not rotating. Therefore, even if the EGR passage 23a is opened and the exhaust pressure of the exhaust passage 12 is reduced by this, the rotation of the turbine 15b is not adversely affected.

As described above, the three-way valve 36 selectively switches either the combustion gas introduction passage 21 or the combustion gas discharge passage 35 in accordance with the running state of the vehicle to open the gas passage. Since it is a valve, the three-way valve 36 is called a gas flow path switching valve.

Further, in the intake passage 11, the intake throttle valve 38
An intake pressure sensor 39 is mounted between the compressor and the compressor 15a. If the combustion type heater 17 is operated when the pressure of the intake system exceeds a predetermined value, the combustion gas emitted from the combustion type heater 17 is exhausted through the combustion gas introduction passage 21 even when the engine I is operating. Can be flowed to passage 12.
Note that the "predetermined value" means that the pressure of the engine intake system is equal to or higher than the predetermined value, and the pressure of the engine intake system is higher than the pressure of the engine exhaust system when the combustion heater is operated, so that backflow does not occur. Therefore, it means the value at which the combustion gas of the combustion type heater can flow toward the engine exhaust system.

Further, as the high output request judging means for judging whether or not the internal combustion engine is required to output a high output, there is a computer, that is, a central processing control unit CPU which is a component of the engine control unit ECU. The CPU is provided with various sensors such as an accelerator opening sensor and a rotation speed sensor provided in the engine I regardless of the description.
It is determined whether or not the internal combustion engine is required to have a high output, based on the value detected for each operating state. Then, according to the determination result, the CPU determines that the three-way valve 36 or the intake throttle valve 3
Activate 8. As a result, the combustion gas introduction passage 21 and the intake passage 11 are opened / closed to distribute the combustion gas to the required places. <Operation and Effect of Embodiment> Next, the operation and effect of the embodiment will be described.

The engine I is a switching valve when a high output demand, that is, a demand for supercharging intake air in the intake passage 11 is determined by the high output demand determination means CPU. The three-way valve 36 is switched by the boost pressure to open the combustion gas introduction passage 21. At this time, if the combustion heater 17 is operating, the combustion gas flows into the exhaust passage 12 via the combustion gas introduction passage 21. The combustion gas introduction passage 21 is a passage for introducing the combustion gas of the combustion heater 17 into the exhaust passage 12 without passing through the cylinder 2. Therefore, at the time of supercharging which is a high output, the combustion gas becomes
I can't go in. Since the combustion gas does not enter the cylinder 2 in this way, the amount of oxygen occupied in the intake air increases accordingly.
Therefore, the combustibility is not deteriorated at the time of supercharging, but the combustibility is improved.

The three-way valve 36, which is a switching valve, operates by receiving the boost pressure generated in the intake passage by the compressor 15a. If the three-way valve 36 operates by supercharging pressure, a special mechanism for operating the three-way valve 36 can be dispensed with. Therefore, the size of the device can be reduced and the cost can be reduced.

[0035]

According to the internal combustion engine having the combustion type heater of the present invention, in the internal combustion engine having the combustion type heater and injecting the combustion gas into the cylinder, the startability is improved and the warm-up is promoted. In particular, the combustibility is not deteriorated at the time of high output, and the combustibility can be improved.

[Brief description of 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, showing an operating state in the case of supercharging.

FIG. 2 is a schematic configuration diagram of an embodiment of an internal combustion engine having a combustion heater according to the present invention, showing an operating state in the case of no supercharging.

[Explanation of symbols]

I ... Diesel engine (internal combustion engine) 2 ... Cylinder 2a ... Cylinder header 3 ... Intake device 4 ... Exhaust device 5 ... Piston 6 ... Combustion chamber 8 ... Intake port 8a ... Intake valve 9 ... Exhaust port 9a ... Exhaust valve 10 ... Injector 11 ... intake passage 12 ... exhaust passage 15a ... turbocharger (supercharger) compressor 15b ... turbocharger turbine 17 ... combustion heater 19 ... catalytic converter 21 ... combustion gas introduction passage 23 ... exhaust gas recirculation device (EGR device) 23a ... EGR passage 23b ... EGR valve 33 ... Air supply passage 35 ... Combustion gas discharge passage 36 ... Three-way valve (switching valve) 38 ... Intake throttle valve 39 ... Intake pressure sensor C1 ... Connection point between air supply passage 33 and intake passage 11 C2 ... Connection point between the combustion gas discharge passage 35 and the intake passage 11 C3 ... Location on the upstream side of the catalytic converter 19 ( Baked junction of the exhaust passage 12 of the gas introduction passage 33) CPU ... high output request detector

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02M 31/08 301 B60H 1/22 F01N 3/36 F02M 25/07 570 F02M 31/07

Claims (3)

(57) [Claims] 1. A combustion heater for heating engine-related elements by the heat obtained by burning fuel, and a combustion gas discharge passage for discharging combustion gas of the combustion heater to an intake passage of an internal combustion engine, A combustion gas introduction passage for introducing the combustion gas flowing through the combustion gas discharge passage to the exhaust passage of the internal combustion engine without passing through the cylinder, and a passage for selectively switching between the combustion gas introduction passage and the combustion gas discharge passage. A switching valve for opening, and a high output request determination means for determining whether or not the internal combustion engine requires a high output when the internal combustion engine is in operation, and the internal combustion engine is requested for a high output. And the high output request determining means determines that the combustion type heater that guides the combustion gas of the combustion type heater to the exhaust passage by switching the switching valve to open the combustion gas introduction passage. Internal combustion engine having. 2. The internal combustion engine includes a supercharger for supercharging intake air in the intake passage, and when the supercharger supercharges the intake passage, the switching valve is switched to introduce the combustion gas. An internal combustion engine having a combustion type heater according to claim 1, wherein a passage is opened. 3. The internal combustion engine having a combustion heater according to claim 2, wherein the switching valve operates by receiving supercharging pressure generated in the intake passage.