JP2000186637A - Internal combustion engine having combustion type heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the lowering of combustibility at least during high output, in an internal combustion engine to improve startability and promote warming-up by introduction of combustion gas of a combustion type heater to a cylinder. SOLUTION: This internal combustion engine comprises a combustion type heater 17 to increase the temperature of an engine-related element, a combustion gas discharge passage 35 to discharge combustion gas of the heater 17 to an intake passage 11; a combustion gas lead-in passage 21 to guide combustion gas, flowing through the combustion gas discharge passage 35, to an exhaust passage 12 not through a combustion gas cylinder 2; a switch valve 36 to selectively switch and open either the combustion gas lead-in passage 12 or the combustion gas discharge passage 35; and a CPU being a high output demand deciding means to decide whether, during engine operation, an engine 1 is demanded for a high output. When it is decided by a high output demand deciding means that a high output is demanded, the switch valve 36 is switched to open a combustion gas lead-in passage 21 to guide combustion gas to the exhaust passage 12.

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 the startability particularly in cold weather and to promote warm-up.

For example, Japanese Patent Application Laid-Open No. 62-75069 discloses a combustion type heater provided in an intake passage of an internal combustion engine.
A technique is shown in which combustion gas emitted from a combustion heater is supplied to a cylinder via the intake passage. Putting the combustion gas from the combustion type heater into the cylinder means taking the combustion gas as intake air. Since combustion gas is also exhaust gas, putting combustion gas, which is exhaust gas, into the cylinder means that the amount of fresh air occupying the intake air of the internal combustion engine decreases accordingly, that is, the amount of oxygen supplied to the cylinder decreases. become. For this reason, putting combustion gas into the cylinder is not preferable from the viewpoint of combustibility.

[0004]

On the other hand, an internal combustion engine provided with a turbocharger as a supercharger, that is, a so-called turbo-charged engine is well known, and even with this turbo-charged engine, it is possible to improve the startability and promote warm-up. In order to achieve this, a technique of putting combustion gas of a combustion heater into a cylinder can be applied. Even in such a case, the problem of flammability may occur.
Also, for engines with a high focus on high power output, such as engines with turbochargers, the combustion gas from the combustion heater is transferred to the cylinder at high power, in other words, when it is necessary to maximize engine performance. , Engine performance is reduced as described above. For this reason, driving feeling and drivability may be reduced.

The present invention has been made under such a technical background. In an internal combustion engine in which combustion gas of a combustion type heater is injected into a cylinder to improve startability and promote warm-up, at least a high output power is required. It is an object to prevent a decrease in flammability in the method.

[0006]

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

That is, a combustion heater for raising the temperature of an engine-related element by heat obtained by burning fuel, a combustion gas discharge passage for discharging combustion gas from the combustion heater to an 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 either the combustion gas introduction passage or the combustion gas discharge passage. A switching valve for opening, and high output request determining means for determining whether the internal combustion engine is required to have a high output when the internal combustion engine is operating, wherein the internal combustion engine is required to have a high output. And the high output request determination means determines that the switching valve is switched to open the combustion gas introduction passage, thereby guiding the combustion gas of the combustion heater to the exhaust passage. An internal combustion engine having a motor.

Here, the "combustion gas introduction passage" is desirably a bypass passage which connects the intake system and the exhaust system and bypasses the engine body. However, even if the bypass passage connects the intake system and the exhaust system and bypasses the engine body, the exhaust gas is returned from the exhaust system to the intake system during the operation of the internal combustion engine for the purpose of reducing NOx, even if the exhaust gas is recirculated. It does not include devices (hereinafter referred to as “EGR devices”). This is because the EGR device operates for the purpose of reducing NOx in the middle and low load range when the engine is operating, and the exhaust gas flows through the EGR passage which is a main component of the EGR device and actually connects the intake system and the exhaust system.

The "high-power-request determining means" is a computer, that is, a central processing control unit (hereinafter "CP") which is a component of an engine control unit (hereinafter referred to as "ECU").
U ". ). The CPU determines whether 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 type heater according to the present invention, when the CPU which is the high output request determination means determines that the internal combustion engine is required to have high output, the CPU determines whether the internal combustion engine requires the high output. A switching valve that selectively switches any one opens a combustion gas introduction passage. Therefore, if the combustion heater operates at this time, the combustion gas guides the combustion gas to the exhaust passage via the combustion gas introduction passage. The combustion gas introduction passage is a passage for introducing the combustion gas of the combustion 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 at the time of high output of the internal combustion engine. 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 related art in which the combustion gas is introduced into the cylinder at the time of high output, the combustibility is improved, not to mention lowering of the combustibility.

As a further preferred means, the internal combustion engine has a supercharger for supercharging intake air into an intake passage. When the supercharger supercharges the intake passage, the switching valve is switched to switch over the combustion. The gas introduction passage may be opened. The term “supercharging” refers to a case where the engine load is large, such as when the internal combustion engine is rotating at high speed or when accelerating, and when the intake passage is higher than the atmospheric pressure. Therefore, the case of no supercharging is other than that, for example, a case where the engine is in a middle to low load range.

Therefore, the supercharging is a time when the internal combustion engine is required to have a high output, so that the same operation and effect as described above can be obtained. Further, the switching valve may be operated by receiving a supercharging pressure generated in the intake passage. If the switching valve is operated by the supercharging pressure, a special mechanism for operating the switching valve becomes unnecessary. Therefore, the size of the apparatus can be reduced accordingly, and the cost can be reduced.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 includes a cylinder 2, an intake device 3 for feeding air required for combustion into the cylinder 2, and a cylinder 2.
And 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 thereon. A piston 5 is provided in the cylinder so as to be vertically movable. A combustion chamber 6 is formed in a piston head constituting the upper part of the piston 5.

The cylinder head 2a is provided with an intake port 8 and an exhaust port 9 that face the combustion chamber 6 when the piston 5 comes up. The intake port 8 and the exhaust port 9 incorporate an intake valve 8a and an exhaust valve 9a, respectively. An injector 10 for injecting fuel into the cylinder 2 is disposed between the two valves so as to face the cylinder 2.

The injector 10 receives a pump pressure from an injection pump (not shown) to eject 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 outside air entering the engine I as a starting point and an intake port 8 as a terminating end. And the air cleaner and intake port 8
A plurality of intake system structures, a turbocharger, that is, a compressor 15 of a turbocharger,
a, a combustion heater 17 for raising the temperature of an engine-related element such as engine cooling water with heat obtained by burning fuel, an intercooler as an intake cooling device (not shown), an intake manifold as an intake branch pipe, and the like are arranged. It is.

The exhaust device 4 has the exhaust port 9 as a starting end and a muffler (not shown) as an end. In 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, a catalytic converter 19 as a gas purification device, and the like are arranged.
The catalytic converter 19 mainly purifies the exhaust gas of the engine I and purifies the combustion gas of the combustion heater 17 together. The catalytic converter 19 contains a catalyst (not shown) therein. The catalyst is activated when it reaches a certain temperature, thereby purifying exhaust gas and the like.

The intake device 3 and the exhaust device 4 are connected by two connecting pipes that connect the two separately, that is, a combustion gas introduction passage 21 and an EGR device 23. For more information,
The combustion gas introduction passage 21 is a bypass passage that bypasses the engine body (strictly, the cylinder 2). Therefore, the combustion gas of the combustion type heater 17 is
After passing through 1, the air 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 discharged from the exhaust port 9 to the intake system, thereby reducing nitrogen oxides generated in the cylinder 2. The EGR device 23 includes an EGR passage 23a as an exhaust recirculation passage connecting 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, for example, when the engine I is in a low or middle speed range (hereinafter referred to as "normal running") such as when the engine I is at low speed or medium speed. Exhaust gas is returned from the exhaust system to the intake system. The EGR device 23 does not operate during idling and at high speed. This is because when idling, the engine temperature is low and the NOx reduction effect is small. Further, when the EGR passage 23a is opened at high speed, the exhaust pressure in the exhaust passage 12 decreases, and the rotation of the turbine 15b decreases.

On the other hand, the combustion type heater 1 belonging to the intake device 3
7 burns fuel together with an air supply passage 33 for supplying air from the intake passage 11 to the combustion type heater 17 and combustion air supplied from the air supply passage 33, and then burns the combustion gas of the combustion type heater 17 And a combustion gas discharge passage 35 that discharges to 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 type heater 17 has a blower fan 17a for adjusting the amount of air flowing through an air flow passage (not shown) of the combustion type heater 17.

The air supply passage 33 of the intake passage 11
And a connection point C1 between the intake passage 11 and a connection point C2 between the combustion gas discharge passage 35 and the intake passage 11,
An intake throttle valve 38 for restricting intake air passing through the intake passage 11 is provided.

In the middle of the combustion gas discharge passage 35, a three-way valve 36 is provided. 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 a location C3 in the vicinity of the upstream side. In addition, three-way valve 3
6 is connected to the compressor 15a so that it operates under the supercharging pressure. .

As shown in FIG. 1, at the time of supercharging, that is, at the time of high output of the engine I, 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 portion C3 of the exhaust passage 12 through a part of the combustion gas discharge passage 35 and the combustion gas introduction passage 21. . Since the point C3 is located near and upstream of the catalytic converter 19, the combustion gas that has reached the point C3 is
Enter 9 and activate the catalyst.

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

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, but flows to a location C 3 near the upstream side of the catalytic converter 19. That is, since the combustion gas discharge passage 35 is closed, the combustion gas from the combustion heater 17 does not flow into the intake passage 11. Therefore, the combustion type heater 1
Only the outside air, which does not contain the combustion gas emitted from the intake passage 7 and is introduced as it is from the intake passage 11, flows.

As shown in FIG. 2, in the case of no supercharging, the three-way valve 36 closes the combustion gas introduction passage 21. Conversely, the combustion gas discharge passage 35 opens. Therefore, in this case, the combustion gas flows into the combustion gas discharge passage 3 as indicated by the solid line arrow in FIG.
5 to the intake passage 11 and then the cylinder 2
It works inside to warm up the engine. At this time, the intake throttle valve 38 remains open. Therefore, the intake air toward the cylinder 2 is a mixture of the combustion gas and the outside air.

When the engine temperature rises during supercharging and during normal running, 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 shown by the dashed arrow in FIG. In this case, since it is not at the time of supercharging, the turbine 15b is not rotating. Therefore, even if the EGR passage 23a is opened, the rotation of the turbine 15b is not adversely affected even if the exhaust pressure in the exhaust passage 12 is reduced.

As described above, the three-way valve 36 selectively switches between the combustion gas introduction passage 21 and the combustion gas discharge passage 35 to open the gas passage according to the running state of the vehicle. Since it is a valve, the three-way valve 36 is called a gas flow switching valve.

The intake throttle valve 38 in the intake passage 11
An intake pressure sensor 39 is mounted between the compressor and the compressor 15a. If the combustion heater 17 is operated when the pressure of the intake system becomes equal to or higher than a predetermined value, the combustion gas discharged from the combustion heater 17 is discharged through the combustion gas introduction passage 21 even when the engine I is operating. It can flow into the passage 12.
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 type heater is operated, so that no backflow occurs. Therefore, it refers to a value that allows the combustion gas of the combustion heater to flow toward the engine exhaust system.

The high output request determining means for determining whether the internal combustion engine is required to have high output includes a computer, that is, a central processing unit CPU which is a component of the engine control unit ECU. The CPU controls various types of sensors provided in the engine I, such as an accelerator opening sensor and a rotation speed sensor, regardless of whether or not there is a description.
It is determined whether a high output is required for the internal combustion engine based on the value detected for each of the operating states. Then, according to the determination result, the CPU determines whether 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 and closed to distribute the combustion gas to the required locations. <Operation and Effect of Embodiment> Next, the operation and effect of the embodiment will be described.

In the engine I, the switching valve is used when the CPU as the high output request determining means determines that there is a request for high output, that is, there is a request for supercharging the intake passage 11 with the intake passage 11. The three-way valve 36 is switched by the supercharging pressure to open the combustion gas introduction passage 21. At this time, if the combustion heater 17 is operating, the combustion gas flows to 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 at the time of high output, the combustion gas is
Do not enter. Since the combustion gas does not enter the cylinder 2 in this manner, the amount of oxygen occupying the intake air increases accordingly.
Therefore, not only does the combustibility not decrease during supercharging, but also the combustibility improves.

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

[0035]

According to the internal combustion engine having the combustion type heater according to the present invention, in the internal combustion engine having the combustion type heater for improving the startability and promoting the warm-up by putting the combustion gas into the cylinder, In particular, it is possible to not only reduce the flammability at the time of high output but also to improve the flammability.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an internal combustion engine having a combustion-type heater according to the present invention, showing an operating state at the time of supercharging.

FIG. 2 is a schematic configuration diagram of an embodiment of an internal combustion engine having a combustion type heater according to the present invention, showing an operation state in a 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 ... compressor of turbocharger (supercharger) 15b ... turbine of turbocharger 17 ... combustion type 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: catalytic converter 19 Upstream front portion (the junction of the exhaust passage 12 of the combustion gas introducing passageway 33) CPU ... high output request detector

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Claims (3)

[Claims] 1. A combustion heater for raising the temperature of an engine-related element by heat obtained by burning fuel; a combustion gas discharge passage for discharging combustion gas from 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 into the exhaust passage of the internal combustion engine without passing through the cylinder; and a passage for selectively switching either the combustion gas introduction passage or the combustion gas discharge passage. A switching valve for opening, and a high output request determining means for determining whether the internal combustion engine is required to have a high output when the internal combustion engine is operating, wherein the internal combustion engine is required to have a high output. And the high output request determination means determines that the switching valve is switched to open the combustion gas introduction passage, thereby causing the combustion heater to guide the combustion gas of the combustion heater to the exhaust passage. Having an internal combustion engine. 2. The internal combustion engine has a supercharger for supercharging intake air into the intake passage. When the supercharger supercharges the intake passage, the switching valve is switched to introduce the combustion gas. The internal combustion engine having a combustion type heater according to claim 1, wherein the passage is opened. 3. The internal combustion engine having a combustion type heater according to claim 2, wherein the switching valve is operated by receiving a boost pressure generated in the intake passage.