JP2712416B2 - EGR device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an EGR device for an internal combustion engine.

[Conventional technology]

For example, carbon in diesel engine exhaust, from the relationship microparticles contain a relatively large number of such particulate, when a large amount of EGR in order to reduce the NO _X, in the exhaust gas sucked into the cylinder with fresh air Carbon adhered to the inner wall surface of the cylinder and was scraped off into the crankcase by the piston ring, and the amount of carbon dissolved in engine oil tended to increase sharply.

Carbon dissolved in oil promotes oil deterioration and brings about an extremely unfavorable phenomenon such as significantly reducing engine lubricity.

For this reason, Japanese Utility Model Publication No. 61-14616 discloses that a catalyst for collecting carbon is interposed in the middle of the EGR passage and a heater for selectively heating the catalyst is provided, so that the collected carbon is automatically collected. An EGR device for performing a combustion process is disclosed.

[Problems to be solved by the invention]

However, this EGR device still has an insufficient ability to trap fine particles, and thus has the same problems as the conventional ones, that is, a problem of wear of a cylinder and deterioration of engine oil. Further, there is also a problem that a large amount of deposits are deposited in the intake pipe due to the interaction between the oil mist in the blow-by gas and the fine particles in the EGR gas. On the other hand, even if the gap of the filter for collecting carbon is made fine, for example, in order to improve the collecting ability of the fine particles, clogging occurs immediately.

Accordingly, an object of the present invention is to provide an EGR device that prevents the accumulation of deposits in an intake pipe and improves the ability to collect fine particles in EGR gas.

[Means for solving the problem]

The present invention provides an EGR device for an internal combustion engine described in claims 1 and 2 as means for solving this problem.

[Action]

In the EGR device for an internal combustion engine of the present invention, fine particles contained in the EGR gas and oil mist containing sludge contained in the blow-by gas are filtered and collected by the fine particle collecting device. EG mixed into the intake air
The R gas does not contain fine particles or oil mist. Therefore, cylinder wear caused by fine particles,
In addition to solving the problem of deterioration of the engine oil, the problem of deposits being deposited in the intake pipe due to the interaction between the oil mist in the blow-by gas and the fine particles in the EGR gas is also solved. In this case, there is also an advantage that the action of collecting the fine particles in the fine particle collecting apparatus is enhanced by the tackiness of the oil in the blow-by gas that is collected at the same time.

Further, in the present invention, since a heater for heating is disposed directly in the particle collecting device in the EGR passage, the heater is provided when the amount of the particles collected by the particle collecting device reaches a predetermined value. By a simple operation of energizing and heating,
The deposited fine particles can be burned in a fine particle collection device and easily removed on the spot. This makes it possible to quickly and easily recover the collecting ability of the fine particle collecting apparatus. Such a simple collection system and operation is suitable for automatic control by an electronic control unit or the like, resulting in the advantage that the whole system is simple, inexpensive and reliable. . In addition, when the heater is energized at the time of starting the engine at a low temperature, the temperature of the EGR gas rises, and the temperature of the EGR gas is mixed with the intake air, so that the temperature of the intake air also rises. There is also an advantage that the time is shortened.

Further, in the present invention, a switching valve is provided in the blow-by gas recirculation passage, and the passage is switched by the switching valve in a predetermined state. Using this switching valve,
In the case of the EGR device of claim 1, when electricity is supplied to a heating heater provided in the particle collecting device, that is, when burning and removing fine particles deposited on the particle collecting device, When assisting the cold start of the engine, the communication between the blow-by gas recirculation passage and the particulate collection device is cut off. This can prevent high-temperature combustion gas resulting from the combustion of the fine particles from flowing through the blow-by gas recirculation passage and flowing into the head cover of the engine or the like.

Further, in the case of the EGR device according to claim 2, the switching valve is used to change the communication state between the blow-by gas recirculation passage and the particle collecting device when the pressure on the upstream side of the particle collecting device is higher than a predetermined value. In addition to shutting off, the blow-by gas recirculation passage directly communicates with the intake pipe of the internal combustion engine,
The gas can be prevented from flowing backward through the blow-by gas recirculation passage and flowing into the head cover or the like of the internal combustion engine.

In any case, the blow-by gas is directly sent to the intake pipe of the internal combustion engine, as in the case of the normal blow-by gas recirculation passage, bypassing the particulate collection device.
As long as the switching valve has not been so switched, no problems will occur.

〔Example〕

Referring to FIG. 1, 1 is a diesel engine main body, 2 is an intake pipe, 3 is an intake manifold, 4 is an exhaust manifold, 5
Indicates an exhaust pipe. An EGR control valve 7 is provided in the middle of an EGR passage 6 connecting the intake pipe 2 and the exhaust manifold 4. The EGR control valve 7 has a negative pressure chamber 9 and an atmospheric pressure chamber 10 separated by a diaphragm 8, and a diaphragm pressing compression spring 11 is inserted into the negative pressure chamber 9. Further, a valve body 13 that controls opening and closing of the valve port 12 is connected to the diaphragm 8. The negative pressure chamber 9 is connected via a negative pressure introducing pipe 14 to a vacuum pump 15 driven by the engine. In the middle of the negative pressure introducing pipe 14, a negative pressure adjusting valve 16 is provided. The opening and closing of the negative pressure regulating valve 16 is controlled by an on-off signal sent from the electronic control unit 30, and the negative pressure in the negative pressure chamber 9 can be controlled by changing the duty ratio of the on-off signal. The position of the valve 13 is controlled by the magnitude of the negative pressure in the negative pressure chamber 9, thereby controlling the opening of the valve port 12. That is, by changing the duty ratio of the on-off signal sent from the electronic control unit 30, the amount of EGR gas recirculated to the intake pipe 2 via the EGR passage 6 can be controlled. In the EGR passage 6 downstream of the EGR control valve 7, a particle collecting device 17 is provided.

FIG. 2 shows the structure of the particle collecting device 17. Referring to FIG. 2, the metal housing 18 of the particle collecting device 17 includes a central cylindrical portion 18a and conical portions 18b and 18c formed at both ends of the cylindrical portion 18a. A filter-like collection member 19 is housed in the cylindrical portion 18a. Filter-like collection member 19
Is made of a material having a high melting point and a large heat insulating property, for example, alumina, and has a cylindrical core portion 19a having a capillary-shaped void, an outer portion surrounding the core portion 19a and concentric with the core portion 19a and having no void. And a cover 19b. In FIG. 2, the exhaust gas flows in the direction of the arrow, that is, from left to right in the figure. A heater 20 is provided near the left end of the collection member 19. As shown in FIG. 3, the heater 20 is formed in a wavy shape and is disposed over substantially the entire cross section of the core portion 19a. The heater 20 is drawn out via the insulating material 21.

Referring again to FIG. 1, the inside of the head cover (not shown) connected to the crank chamber is provided with a blow-by gas recirculation passage.
The upstream side conical portion 18b of the particle collecting device 17 is connected to the side surface (see FIG. 2) of the fine particle collecting device 17 through the same 22. Blow-by gas recirculation passage
A switching valve 23 is provided in the middle of 22. The switching valve 23 is further connected to the intake manifold 3 via a passage 24. Switching valve
Reference numeral 23 is controlled by the electronic control unit 30 to selectively communicate the inside of the head cover (not shown) with the intake manifold 3 or the upstream conical portion 18b of the particle collecting device 17.

The electronic control unit 30 is composed of a digital computer, and a ROM (read only memory) 32, a RAM (random access memory) 33, a CPU (microprocessor) 34, an input port 35 interconnected by a bidirectional bus 31.
And an output port 36.

As shown in FIG. 1, a pressure for detecting the EGR gas pressure in the EGR passage 6 immediately upstream of the particle collecting device 17 is provided in the EGR passage 6 upstream of the particle collecting device 17 and near the particle collecting device 17. The sensor 50 is mounted. The pressure sensor 50 generates an output voltage proportional to the EGR gas pressure. The pressure sensor 50 is connected to the input port 35 via the AD converter 37. On the other hand, a load sensor 52 that generates an output voltage proportional to the amount of depression of the accelerator pedal 51 is attached to the accelerator pedal 51. This load sensor 52 is connected to the input port 35 via the AD converter 38. The input port 35 is connected to a rotation speed sensor 53 that generates an output signal indicating the engine rotation speed, an integrated rotation speed sensor 54 that generates an output signal for each rotation of the engine, and a starter switch 55.

On the other hand, the output port 36 is connected to the heater 20, the switching valve 23, and the negative pressure regulating valve 16 via drive circuits 39, 40, and 41, respectively.

During normal operation of the engine, the EGR control valve 7 controls the engine speed and the load sensor detected by the speed sensor 53.
Valve port based on accelerator opening detected by 52
The EGR amount is controlled by controlling the opening degree of the twelfth. by this,
An appropriate amount of EGR gas is recirculated into the intake pipe 2 according to the engine operating state.

The switching valve 23 is provided during the normal operation.
The blow-by gas containing oil mist is communicated with the EGR passage 6 immediately upstream of the EGR passage 6 immediately upstream of the particulate collection device 17.
It flows into the passage 6. The oil mist in the blow-by gas is collected by the filter-shaped collection member 19, and the adhesion of the collected oil significantly increases the collection rate of the carbon particles in the EGR gas. Therefore, accumulation of deposits in the intake pipe 2, abrasion of the cylinder, and deterioration of the engine oil are suppressed.

If the EGR gas pressure in the EGR passage 6 upstream of the particulate trap 17 detected by the pressure sensor 50 exceeds a predetermined pressure, the switching valve 23 shuts off the blow-by gas recirculation passage 22 and passes through the passage 24. To allow the inside of the head cover to communicate with the intake manifold 3. This prevents the EGR gas from flowing back into the head cover (not shown) through the blow-by gas recirculation passage 22. As a result, the blow-by gas is discharged into the intake manifold 3.

Each time the integrated engine speed obtained by counting the output signal of the integrated speed sensor 54 reaches a predetermined integrated engine speed, for example, 500,000 times, for a predetermined time, for example, 20 minutes to the heater 20 It is energized. As a result, the filter-shaped collecting member 19 is heated to a high temperature, and the oil and carbon particles collected by the filter-shaped collecting member 19 are burned and removed, thereby preventing the filter-shaped collecting member 19 from being clogged. . When the heater 20 is energized, the EGR control valve 7 is set to a predetermined opening degree, for example, about 20% of full opening, and air necessary for burning oil and carbon particles is supplied. When the heater 20 is energized, the switching valve 23 shuts off the blow-by gas recirculation passage 22, thereby preventing the combustion flame from entering the diesel engine main body 1 via the blow-by gas recirculation passage 22.

When starting the engine, fully open the EGR control valve (opening 100
%) And energize the heater 20. As a result, the EGR gas is heated by the heater, and the heated EGR gas heats the intake air, so that the engine startability at low temperatures can be improved.

Next, a routine for executing this embodiment will be described with reference to FIGS.

FIG. 4 shows a routine for controlling the opening of the EGR control valve 7. This routine is executed by interruption every predetermined time. Referring to FIG. 4, first, at step 60, the engine speed Ne and the accelerator opening θA are read. Subsequently, in step 61, it is determined whether the starter switch 55 is off, and in step 62, it is determined whether the heater 20 is off. If an affirmative determination is made in steps 61 and 62, the process proceeds to step 63, where the opening of the EGR control valve 7 is calculated based on Ne and θA from map 1 (see FIG. 7), and this routine ends. Thereby, the optimal EGR gas amount according to the engine operating state is recirculated into the intake pipe 2.

When a negative determination is made in step 61, that is, when the engine is started, the routine proceeds to step 64, where the EGR control valve 7
Is fully opened (opening 100%), and this routine ends.
As a result, the startability of the engine is improved.

If a negative determination is made in step 62, that is, if the heater 20 is on, the routine proceeds to step 65, where the EGR control valve 7
Is set to 20% of the fully opened position, and this routine ends.
As a result, air necessary for burning the oil and carbon particles collected by the filter-shaped collection member 19 is supplied.

After the above processing, by controlling the negative pressure regulating valve 16
The drive of the EGR control valve 7 is controlled.

FIG. 5 shows a routine for controlling the switching valve 23. This routine is executed by interruption every predetermined time. Referring to FIG. 5, first, in step 70, the fine particle collecting device 17 is used.
The pressure P in the EGR passage immediately upstream is read. Step 71
In step 72, it is determined whether the heater 20 is off.
There it is determined whether the following pressure P _E predetermined. If a positive determination is made in steps 71 and 72, the process proceeds to step 73,
The switching valve 23 allows the blow-by gas recirculation passage 22 to communicate, and this routine ends. As a result, the blow-by gas containing oil mist flows into the EGR passage 6 immediately upstream of the particulate trap 17.
Introduced within.

If either one of step 71 and step 72 is denied, the routine proceeds to step 74, where the blow-by gas recirculation passage is shut off, the inside of the head cover (not shown) is communicated with the intake manifold 3 via the passage 24, and End the routine. As a result, blow-by gas is discharged into the intake manifold 3. When the heater 20 is turned on,
The combustion flame of the collected oil and carbon particles passes through the blow-by gas recirculation passage 22
Inside is prevented. In addition, at the time of P> P _E,
The backflow of the EGR gas into the head cover (not shown) via the blow-by gas recirculation passage 22 is prevented.

FIG. 6 shows a routine for controlling on / off of the heater 20. This routine is executed by interruption every predetermined time. Referring to FIG. 6, first, at step 80, the integrated engine speed N is read. In step 81, it is determined whether the starter switch 55 is off. Starter switch
When 55 is on, that is, when the engine is started, the routine proceeds to step 82, where the heater 20 is turned on. As a result, the startability of the engine is improved. If an affirmative determination is made in step 81, the routine proceeds to step 83, where it is determined whether or not the flag F = 0. If a positive determination is made, it is determined in step 84 whether N is 500,000 times or more. If a negative determination is made, the routine proceeds to step 89, where the heater 20 is turned off, and this routine ends. If a positive determination is made in step 84, N is set to 0 in step 85, and the accumulated engine speed is counted again from 0 by another routine (not shown). In step 86, the flag F is set to 1. If F = 1 in step 83 and a negative determination is made, the condition that N ≧ 500,000 is satisfied and the heater 20 is energized,
Proceed to step 87. In step 87, it is determined whether, for example, 20 minutes have elapsed since the heater was turned on. If a negative determination is made, the routine proceeds to step 82, where the heater 20 is kept turned on, and this routine ends. If affirmative, step
After F is set to 0 at 88, the heater 20 is turned off at step 89, and the routine ends.

The device for collecting fine particles used in the present invention is not limited to the structure shown in FIG. 2, but may be any device capable of collecting and regenerating fine particles.

〔The invention's effect〕

According to the present invention, fine particles contained in the EGR gas, oil mist containing sludge contained in the blow-by gas and the like are filtered and collected by the fine particle collecting device, so that the cylinder generated by the fine particles Wear or
In addition to solving the problem of deterioration of the engine oil, the problem of deposits accumulating in the intake pipe is also solved. Further, there is an advantage that the action of collecting fine particles in the fine particle collecting apparatus is enhanced by the tackiness of the oil in the blow-by gas collected at the same time.

Further, in the present invention, since a heater for heating is directly disposed in the particle collecting device in the EGR passage, the fine particles accumulated in the particle collecting device are burned by a simple operation, so that the in-situ can be achieved. Can be removed. This makes it possible to quickly and easily recover the collecting ability of the fine particle collecting apparatus. According to the present invention, there is an advantage that an EGR device having a simple configuration, a low cost, and a high reliability can be easily obtained. In addition, the heater for heating can be used for the purpose of preheating the intake air flowing into the intake pipe via the EGR gas by energizing at the time of starting the engine at a low temperature to assist the starting of the engine.

In particular, in the EGR device of the present invention, since the switching valve is provided in the blow-by gas recirculation passage, the heater for the fine particle collecting device is energized to remove fine particles deposited on the fine particle collecting device, When assisting the cold start, it is possible to prevent the high-temperature combustion gas due to the combustion of the deposited fine particles from flowing through the blow-by gas recirculation passage into the engine head cover or the like by switching the switching valve. When the pressure on the upstream side of the collector is higher than a predetermined value, it is possible to prevent the EGR gas from flowing backward through the blow-by gas recirculation passage and flowing into the head cover of the internal combustion engine, thereby improving the reliability of the system. Can be.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a diesel engine employing one embodiment of the present invention, FIG. 2 is a partial cross-sectional side view of a particulate collection device, and FIG. 3 is a cross-sectional view taken along line II-II of FIG. Figure 4
5 is a flowchart for controlling the opening degree of the EGR control valve, FIG. 5 is a flowchart for controlling the switching valve, FIG. 6 is a flowchart for controlling the heater, and FIG.
FIG. 3 is a diagram showing a relationship between an R control valve opening, an engine speed, and an accelerator opening. 2: intake pipe, 6: EGR passage, 7: EGR control valve, 17: particulate collection device, 22: blow-by gas recirculation passage.

Continued on the front page (72) Inventor Masaki Takeyama 14 Iwatani, Shimoba-Kadomachi, Nishio City, Aichi Prefecture Inside the Japan Automobile Parts Research Institute Co., Ltd. Within the Research Institute (56) References JP-A-56-54948 (JP, A) JK-56-54262 (JP, U)

Claims (2)

(57) [Claims] 1. An internal combustion engine in which a part of exhaust gas is recirculated into intake air through an EGR passage and an EGR control valve, a particulate collection device is provided in the EGR passage, and the particulate collection device is provided. A blow-by gas recirculation passage is connected to the EGR passage on the more upstream side, and further, a heater for heating is arranged in the particulate collection device, and a switching valve is provided for the blow-by gas recirculation passage connected to the EGR passage. In addition, when the heater for heating provided in the particle collecting device is energized, the blow-by gas recirculating passage is switched by the switching valve, so that the blow-by gas recirculating passage and the particle collecting device are switched. EGR of an internal combustion engine characterized in that it is configured to cut off communication with the engine
apparatus. 2. An internal combustion engine in which a part of exhaust gas is recirculated into intake air through an EGR passage and an EGR control valve, wherein a particulate collection device is provided in the EGR passage, and the particulate collection device is provided. A blow-by gas recirculation passage is connected to the EGR passage on the more upstream side, and further, a heater for heating is arranged in the particulate collection device, and a switching valve is provided for the blow-by gas recirculation passage connected to the EGR passage. And an EGR in the EGR passage on the upstream side of the particulate trapping device.
When the pressure of the gas is higher than a predetermined value, the communication between the blow-by gas recirculation passage and the particle collecting device is cut off by switching the blow-by gas recirculation passage by the switching valve, and the blow-by gas recirculation is performed. An EGR device for an internal combustion engine, wherein a passage is configured to directly communicate with an intake pipe of the internal combustion engine.