JPH05125923A - Exhaust purifying device of internal combustion engine - Google Patents

Abstract

PURPOSE:To suppress increase of a collection amount in the center part of a filter when particule component (particulates) in exhaust gas are collected, and surely prevent the temperature of a filter center part from over-rising when the filter is regenerated. CONSTITUTION:In an exhaust purifying device 3, the case 5 having an aperture larger than the aperture of an exhaust pipe 4 is provided on the exhaust pipe 4 provided between an internal combustion engine main body 17 and a muffler 18, and a filter 6 is housed in the case 5. A straightening vane 12 having a slant face for inducing exhaust gas or regenerated gas to the outer circumferencial part of a filter 6, is provided in the hollow part provided upsteam from the filter 6. In the case of a shaft 6 which is slidable in a sleeve in axial direction, one end thereof is fixed on the upsteam side of the straightening vane 12, and the other end is connected to a link 21 by an electromagnetic actuator 19. The straightening vane 12 is thus moved in axial direction according to collection condition or regeneration condition of the filter 6 so as to control exhaust gas or regenerated gas which flows-in the center part of the filter 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purification device for a diesel engine, and more specifically, to an exhaust gas provided with a flow regulating plate for regulating a flow path of exhaust gas on an upstream side of an exhaust gas purification filter provided in an exhaust passage. Purification device

[0002]

2. Description of the Related Art Conventionally, as an exhaust emission control device for a diesel engine, as disclosed in Japanese Utility Model Laid-Open No. 62-176417, Japanese Utility Model Laid-Open No. 1-174510, Japanese Patent Laid-Open No. 63-285217, etc. It is known that a rectifying plate is provided on the upstream side of the filter in the exhaust passage in order to efficiently collect the particulate components (particulates) such as carbon contained in the exhaust gas on the filter. This type of exhaust gas purification device operates, for example, a rectifying plate so that exhaust gas is actively flowed to the outer peripheral portion of the filter when collecting the fine particle component, and when the filter is regenerated, a central portion of the filter that tends to have a relatively high temperature is used. The flow plate is operated so as to cool the central portion of the filter by positively flowing the regeneration gas.

[0003]

However, according to the conventional exhaust gas purifying apparatus, when the particulate matter component is collected, the flow velocity of the exhaust gas is relatively small and the amount of the particulate matter component accumulated on the outer peripheral portion of the filter is small. As shown in FIG. 11 (A), by the rectifying plate 2 provided on the upstream side of the filter 1,
Exhaust gas is sufficiently introduced into the outer peripheral portion of the filter, but if the flow velocity of the exhaust gas is relatively large and the amount of trapped particulate matter in the outer peripheral portion of the filter increases, as shown in FIG. There is a problem that the amount of fine particle components trapped in the center of the filter tends to increase because the flow around the center of the filter easily flows around between the 1a and the rectifying plate 2.

Further, when the filter center is regenerated, when the combustion in the center of the filter precedes the outer peripheral portion of the filter and reaches the rear end face of the filter, the regenerated air flows only in the center of the filter, so that the center of the filter is overheated due to excess oxygen. There is a problem in that as the temperature rises, unburned particulate components tend to remain on the rear end side of the outer peripheral portion of the filter. The present invention has been made in order to solve such a problem, and suppresses an increase in the amount of the particulate matter collected at the time of collecting the fine particle component, and
An object of the present invention is to provide an exhaust gas purification device for an internal combustion engine, which reliably prevents excessive temperature rise in the center of the filter when the filter is regenerated.

[0005]

An exhaust gas purifying apparatus for an internal combustion engine according to a first aspect of the present invention for solving the above-mentioned problems, comprises:
An exhaust gas purification device comprising a filter provided in an exhaust passage of an internal combustion engine and capable of purifying exhaust gas, and heating means for regenerating the filter by burning exhaust gas components collected by the filter, wherein the exhaust gas Provided on the filter upstream side of the passage so as to face the filter upstream side end surface,
A rectifying plate that guides exhaust gas to the outer peripheral portion of the filter, a link mechanism that is fixed to the rectifying plate, and is movable in the axial direction of the rectifying plate, and the filter upstream end face and the rectifying member by driving the link mechanism. An actuator that adjusts the distance to the plate is provided.

An exhaust gas purifying apparatus for an internal combustion engine according to a second aspect of the present invention is a filter provided in an exhaust passage of the internal combustion engine for purifying exhaust gas, and the exhaust gas component collected by the filter is combusted to burn the filter. An exhaust gas purification device comprising: a heating means for regenerating the exhaust gas, wherein the exhaust gas purification device is provided on the filter upstream side of the exhaust passage so as to face the filter upstream end surface, and is made of an elastic body that guides exhaust gas to the filter outer peripheral portion. A rectifying plate, a shaft that is attached to the central portion of the rectifying plate, supports the rectifying plate in an axially slidable manner, and is provided between the filter and the rectifying plate, and adjusts the wind pressure of the fluid passing through the exhaust passage. Accordingly, there is provided a stopper for slidably supporting the downstream end portion of the flow straightening plate in the radial outward direction of the flow straightening plate.

An exhaust gas purification apparatus for an internal combustion engine according to a third aspect of the present invention is a filter provided in an exhaust passage of the internal combustion engine and capable of purifying exhaust gas, and the filter by burning exhaust gas components collected by the filter. An exhaust emission control device comprising: a heating means for regenerating the exhaust gas, wherein the filter upstream side of the exhaust passage is provided to face the filter upstream end surface, and a rectifying plate that guides exhaust gas to the filter outer peripheral portion, A shaft that slidably supports the flow straightening plate in the axial direction, a biasing unit that is inserted into the shaft and biases the flow straightening plate toward the upstream side, and a fluid that is fixed to the shaft and flows through the exhaust passage. A rotating body that rotates at a rotational speed according to the flow velocity, and a flyweight that rotates together with the rotating body and moves the flow straightening plate to the downstream side against the biasing means as the centrifugal force increases. Characterized in that it has a.

[0008]

According to the exhaust gas purifying apparatus of the first aspect of the present invention, the rectifying plate is moved in the axial direction by the driving force of the actuator in response to the signal from the control unit or the like, and the exhaust gas or the regenerated gas is prevented from flowing into the central portion of the filter. Control. According to the exhaust gas purifying apparatus of the second aspect of the present invention, the end portion of the straightening plate made of an elastic body is elastically deformed so as to expand in the radially outward direction according to the wind pressure to prevent the exhaust gas or the regeneration gas from flowing into the filter central portion. Control. According to the exhaust emission control device of the third aspect of the present invention, the flow straightening plate moves in the axial direction by the centrifugal force of the flyweight that rotates according to the flow velocity of the fluid, and controls the inflow of exhaust gas or regenerated gas into the center of the filter. ..

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an exhaust emission control device according to a first embodiment of the present invention.
As shown in FIG. As shown in FIG. 2, the exhaust emission control device 3 has a case 5 having a diameter larger than the diameter of the exhaust pipe 4 in the exhaust pipe 4 between the internal combustion engine body 17 and the muffler 18, and a honeycomb-shaped case 5 is provided in the case 5. It contains the filter 6. The exhaust pipe 4 is provided with a bypass pipe 7 that bypasses the filter 6 from the branch portion 4a of the exhaust pipe 4 to the muffler 18, and exhaust gas can be introduced into the bypass pipe 7 by opening and closing an exhaust control valve 8 provided in the bypass pipe 7. It has become. An air pump 9 provided on the upstream side of the case 5 of the exhaust pipe 4 can supply secondary air as a regeneration gas to the filter 6 when the filter 6 is regenerated.

The filter 6 is of a wall flow monolith type formed of a porous ceramic such as cordierite or alumina, and the partition wall extending in the exhaust gas flow direction of the filter 6 collects fine particle components in the exhaust gas. .. The upstream end surface 6a of the filter 6 is provided with an electrothermal heater 10 made of a nichrome material, a kathal material or the like, and when the particulate component trapped in the filter 6 reaches a predetermined amount, the electrothermal heater 10 is energized. , Filter 6
Is played.

As shown in FIG. 1, in the cavity 11 on the upstream side of the filter 6, a conical straightening plate 12 for guiding the exhaust gas or regeneration gas introduced into the case 5 to the outer peripheral portion of the filter.
Is provided. The slope 12a of the straightening vane 12 is formed to incline radially outward from the center of the straightening vane 12 toward the downstream side of the case 5, and is fixed to the top of the slanting face 12a by the stay 14 on the case 5. Sleeve 1
One end of a shaft 16 slidable in the shaft 5 is fixed. The other end of the shaft 16 has an electromagnetic actuator 19
Is connected to a link 21 rotatable about a fulcrum 20 within a predetermined angle range, and transmits the operating force of the electromagnetic actuator 19 to the rectifying plate 12. Therefore, the rectifying plate 12 can move in the axial direction in conjunction with the electromagnetic actuator 19, and changes the distance L between the rectifying plate 12 and the filter 6.
A disc-shaped stopper 22 is provided on the upstream end face 6 a of the filter so that the rectifying plate 12 does not come into contact with the filter 6.

The amount of movement of the current plate 12 is controlled by the control device (EC
U) 23. The ECU 23 includes exhaust pressure sensors 24, 25 for detecting exhaust pressures on the upstream and downstream sides of the filter 6, temperature sensors 26, 27 for detecting temperatures of the central portion and the outer peripheral portion of the downstream end face 6b of the filter 6,
In addition, the detection signal of the rotation speed sensor 28 shown in FIG. 2 for detecting the rotation speed of the internal combustion engine body 17 is input. And
The ECU 23 arithmetically processes each detection signal, determines an appropriate amount of movement of the rectifying plate 12, and outputs a drive signal to the electromagnetic actuator 19.

At the time of collecting the fine particle component, the exhaust gas is rectified by the straightening plate 1.
2 is positively introduced to the outer peripheral portion of the filter upstream end surface 6a. Therefore, the particulate component in the exhaust gas is collected in the filter outer peripheral portion before the filter central portion. Then, as the collection of the filter outer peripheral portion progresses, the differential pressure across the filter increases. When the exhaust pressure sensors 24 and 25 detect that a predetermined differential pressure across the filter has been reached, the electromagnetic actuator 19 moves the rectifying plate 12 from the position shown in FIG. 1 so as to approach the filter upstream end face 6a.
Thereby, the exhaust gas is prevented from flowing into the downstream side of the straightening vane 12, and the function of the straightening vane 12 can be sufficiently exhibited. Regarding the movement of the rectifying plate 12, in addition to when the differential pressure across the filter 12 exceeds a predetermined value,
This is also carried out at the time of regeneration, when unburned residue is generated in the fine particle component, when the rotational speed of the internal combustion engine body 17 becomes large, and the flow velocity of exhaust gas becomes high. In this case, the ECU 23 determines an appropriate amount of movement of the straightening vane 12 based on the detection signals of the temperature sensors 26 and 27 and the rotation speed sensor 28, respectively.

When the electric heater 10 is energized when the filter 12 is regenerated and the secondary air is introduced into the case 5 from the air pump 9 at a predetermined flow velocity, the fine particle component collected by the filter 12 is burned and the upstream of the filter 12 is heated. Combustion propagates from one side to the downstream side. In this case, the interval L between the filter upstream end surface 12a and the straightening vane 12 is set to a distance such that the secondary air slightly goes around to the downstream side of the straightening vane 12. When the temperature sensors 26 and 27 detect that the temperature of the center of the filter is higher than the temperature of the outer periphery by a predetermined temperature or more, the rectifying plate 12 moves so as to come as close as possible to the filter 12 side, as shown in FIG. To do. As a result, the oxygen concentration in the center of the filter is reduced, and it is possible to prevent excessive temperature rise in the center of the filter.

Next, an example of controlling the amount of movement of the current plate 12 will be described with reference to the flow charts shown in FIGS. When it is determined in step 31 that the rotational speed NE of the internal combustion engine body 17 is 800 rpm or more when collecting the fine particle component,
In step 32, the maximum temperatures T _1max and T _2max of the central portion and the outer peripheral portion of the filter downstream side end surface 6b are called, and in step 33, the exhaust pressure P on the upstream side and the downstream side of the filter 12 is called.
₁ and P ₂ are measured, and the corrected exhaust pressures p ₁ and p ₂ on the upstream side and the downstream side of the filter 12 corrected at the position of the straightening plate 12 are calculated in step 34. Then, in step 35, it is judged whether or not the maximum temperature T _1max is 600 ° C. or higher, and 600 ° C.
If so, the process proceeds to step 36, and if it is less than 600 ° C., the process proceeds to step 42 described later. If the maximum temperature T _2max is determined to be 600 ° C. or higher in step 36, the process proceeds to step 37, and if it is less than 600 ° C., the process proceeds to step 49 described later. In step 37, the difference between the corrected exhaust pressure p ₁ and the corrected exhaust pressure p ₂ is calculated, and this difference is used as the filter differential pressure coefficient K.
If it is ₁ or more, the interval L between the flow straightening plate 12 and the filter upstream end face 12a is set to 1 cm in step 41, and if this difference is smaller than the filter pressure difference coefficient K _1, step 3
In step 8, it is determined whether the rotational speed NE of the internal combustion engine body 17 is less than 2000 rpm. If it is less than 2000 rpm, the interval L is set to 3 cm in step 39. If the rotational speed NE is 2000 rpm or more in step 38, the interval L is set to 0.8 cm in step 40.

In step 35, the maximum temperature T_1maxIs 600 ° C
If it is determined to be less than, as shown in FIG.
Maximum temperature T at 2_2maxIs above 600 ℃,
If it is 600 ° C. or higher, in step 43, the corrected exhaust pressure p₁ 
And p₂ Difference and filter differential pressure coefficient K₁ And compare
Positive exhaust pressure p₁ And p₂ Is the filter differential pressure coefficient K₁ Less than
If so, set interval L to 1.5 cm in step 44
And filter differential pressure coefficient K ₁ If so, step 45
To set the interval L to 0.5 cm. Also step
Maximum temperature T at 42_2maxIs less than 600 ° C,
Corrected exhaust pressure p₁ And p₂ Difference and filter differential pressure
Coefficient K₂ Compensated exhaust pressure p₁ And p ₂ The difference between
Differential pressure coefficient K₂If it is less than, it is step 47
L is set to 0.8 cm, filter differential pressure coefficient K₂ Above
If so, set interval L to 0.5 cm in step 48
To do.

Further, when the maximum temperature T _2max is determined to be less than 600 ° C. in step 36 shown in FIG. 4, as shown in FIG. 6, the difference between the corrected exhaust pressures p ₁ and p ₂ and the filter differential pressure are step 49. comparing the coefficient K _3, corrected if the difference between the exhaust pressure p ₁ and p ₂ is less than the filter differential pressure coefficient K _3, and set the distance L to 0.8 in step 50, the filter differential pressure coefficient K ₃ or more If so, the interval L is set to 0.5 cm in step 51. When the set value of the interval L is determined in this way, step 33 and subsequent steps are repeated.

During filter regeneration, the interval L is set in step 52.
For example, set to 3 cm, step 53 and step 5
4 shows the temperature of the central part and the outer peripheral part of the filter downstream side end face 6b.
Degree T ₁ , T₂ Is measured, and in step 55,
For temperature T₁ And T₂ Remember the maximum value of. That
In step 56, the required playback time and the playback set time T_M When
And the required playback time is the playback set time T_M Or more
For example, in step 57, the reproduction is stopped and the process returns to the start of the reproduction. Playback
Required time is playback set time T_M If less than, step 58
To the center temperature T of the downstream end face 6b of the filter.₁ Is 8
It is determined whether the temperature is 00 ° C or higher. Center temperature T₁ But
If it is determined that the temperature is 800 ° C. or higher, step 59
The interval L is set to 0, and the outer peripheral temperature T is set in step 60.₂ 
Is less than 800 ° C. And the
Temperature 60 at the outer circumference₂ Is determined to be below 800 ° C
If so, the air pump 9 is stopped in step 62.
If the air pump 9 is stopped,
In step 63, the air pump 9 is driven, and in step 53
Return. Further, in step 60, the outer peripheral temperature T₂ Is over 800 degrees
If it is judged to be above, the air pump 9 is stopped in step 61.
Then, the process returns to step 32.

Next, the second and third embodiments of the present invention will be described. An exhaust emission control device according to the second embodiment is shown in FIG. The exhaust gas purification device 70 is provided with a tubular straightening plate 12 made of an elastic body in a hollow portion on the upstream side of the filter 6. The current plate 12 is formed so as to incline radially outward as it faces the downstream side of the case 5, and the upstream opening 12 is formed.
The disk 72 is fixed to c, and the stopper 22 fixed in the case 5 is in contact with the downstream opening 12d. The shaft 16 fixed on the upstream side of the stopper 22 has a disc 72
It is slidably inserted in a shaft hole 76 formed in the central portion of the. The circular plate 72 arranged so as to be orthogonal to the flow direction of the exhaust gas is such that the exhaust gas introduced into the case 5 is the straightening plate 12
The stopper 22 arranged in parallel with the disc 72 is formed in a stitch shape so as to facilitate the circulation of exhaust gas to the downstream side. The distance L ₂ between the stopper 22 and the upstream end surface 6a of the filter is set to such a distance that the straightening plate 12 is not damaged by the heat of the electric heater 10.

When the flow velocity of the exhaust gas increases during the collection of the fine particle component, the exhaust gas flowing through the central portion of the case 5 receives wind pressure on the disk 72, and as shown by the broken line 12 in FIG. At the same time, the downstream opening 12 of the straightening plate 12
d slides on the stopper 22 in the radially outward direction. For this reason,
Even when the flow velocity of the exhaust gas is relatively high, the exhaust gas is less likely to enter the inside of the straightening vane 12. Further, when the flow velocity of the regeneration gas is increased during regeneration of the filter 6, it is possible to prevent the regeneration gas from being supplied to the central portion of the filter 6 more than necessary,
It is possible to prevent an excessive temperature rise in the center of the filter.

An exhaust emission control device according to a third embodiment of the present invention is shown in FIGS. 9 and 10. The exhaust emission control device 80 is configured so that the flow regulating plate 12 can be moved by the centrifugal force of the flyweight 81 arranged in the hollow portion 11 inside the case 5. The rectifying plate 12 having the inclined surface 12a inclined radially outward according to the downstream side of the case 5 has a shaft hole 83 formed at the top of the slope surface 12a, and the shaft hole 83 is formed in the shaft 16 arranged in the axial direction. It is slidably inserted. Shaft 16
Is rotatably supported by a support member 86 fixed to the case 5, and a fan 87 that rotates together with the shaft 16 according to the flow rate of exhaust gas is fixed to the upstream end of the shaft 16. A spring seat 88 is formed at the downstream end of the shaft 16, and a coil spring 89 that biases the current plate 12 to the upstream side is disposed on the spring seat 88. Shaft 1
A weight holder 90 and a flyweight 81 are rotatably attached between the current plate 12 of 6 and the fan 87 in association with the fan 87. The flyweight 81 is rotatable radially outward about a fulcrum 81a by a centrifugal force. As shown in FIG. 10, the sleeve 91 slidably inserted into the shaft 16 contacts the cam portion 81 b of the flyweight 81 and the top portion of the flow regulating plate 12. The weight and center of gravity of the flyweight 81, the profile of the cam portion 81b, the set load of the coil spring 89, the propeller shape of the fan 87, and the like are set so that the straightening plate 12 is at a predetermined position with respect to the flow velocity of the exhaust gas.

When the exhaust gas is introduced into the case 5 shown in FIG. 9, the fan 87 and the fly weight 81 rotate according to the flow velocity of the exhaust gas. At this time, when the flow velocity of the exhaust gas is relatively low, the centrifugal force acting on the flyweight 81 is smaller than the set load on the coil spring 89, so the flow straightening plate 12 does not move. When the flow velocity of the exhaust gas becomes relatively large, the rotation speed of the fan 87 becomes large, and when the centrifugal force of the fly weight 81 becomes larger than the set load of the coil spring 89, the cam portion 81b pushes the sleeve 91, and the straightening plate 12 is drawn. It is moved in the direction of the arrow indicated by 10. This prevents the exhaust gas from easily entering the central portion of the filter 12 depending on the flow velocity of the exhaust gas. Further, also when the filter is regenerated, the rectifying plate 12 controls the introduction of the regenerated gas locally to the center of the filter as the flow velocity of the regenerated gas increases.

[0023]

As described above, according to the exhaust gas purifying apparatus for an internal combustion engine of the present invention, since the position of the straightening vane is made variable according to the collecting condition or the regenerating condition of the filter, the particulate component in the exhaust gas is There is an effect that it is possible to suppress the accumulation of oxygen in the center of the filter and to reduce it, and to reduce the oxygen concentration in the center of the filter to prevent a local temperature rise.

[Brief description of drawings]

FIG. 1 is a partial schematic diagram showing an exhaust emission control device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing an exhaust emission control device according to a first embodiment of the present invention.

FIG. 3 is a partial schematic view for explaining the operation of the exhaust emission control device according to the first embodiment of the present invention during filter regeneration.

FIG. 4 is a flowchart showing an example of control of a current plate during exhaust gas purification according to the first embodiment of the present invention.

FIG. 5 is a flowchart showing a continuation of part A shown in FIG.

FIG. 6 is a flowchart showing the continuation of part B shown in FIG. 4;

FIG. 7 is a flowchart showing an example of control of a rectifying plate during filter regeneration according to the first embodiment of the present invention.

FIG. 8 is a partial schematic view showing an exhaust emission control device according to a second embodiment of the present invention.

FIG. 9 is a partial schematic diagram showing an exhaust emission control device according to a third embodiment of the present invention.

FIG. 10 is a partially enlarged view showing an exhaust emission control device according to a third embodiment of the present invention.

FIG. 11 is a partial schematic view showing an exhaust emission control device according to a conventional example.

[Explanation of symbols]

 Reference Signs List 4 exhaust pipe (exhaust passage) 6 filter 6a filter upstream end face 10 electric heater (heating means) 12 straightening plate 12d downstream end (downstream opening) 16 shaft 17 internal combustion engine body (internal combustion engine) 19 electromagnetic actuator (actuator) ) 20 fulcrum (link mechanism) 21 link (link mechanism) 81 fly weight 87 fan (rotating body) 89 coil spring (biasing means) L interval

Claims (3)

[Claims] 1. An exhaust gas purification apparatus comprising a filter provided in an exhaust passage of an internal combustion engine and capable of purifying exhaust gas, and heating means for regenerating the filter by burning exhaust gas components collected by the filter. There is a rectifying plate that is provided on the filter upstream side of the exhaust passage so as to face the filter upstream side end face, and guides exhaust gas to the filter outer peripheral portion, and is fixed to the rectifying plate, and the rectifying plate is in the axial direction. An exhaust gas purifying apparatus for an internal combustion engine, comprising: a movable link mechanism; and an actuator that drives the link mechanism to adjust a distance between the filter upstream end surface and the rectifying plate. 2. An exhaust gas purification apparatus comprising a filter provided in an exhaust passage of an internal combustion engine and capable of purifying exhaust gas, and heating means for regenerating the filter by burning exhaust gas components collected by the filter. There is a rectifying plate which is provided on the filter upstream side of the exhaust passage so as to face the filter upstream side end face, and which is made of an elastic body that guides exhaust gas to the filter outer peripheral portion, and is attached to the central portion of the rectifying plate. A shaft that slidably supports the flow straightening plate in the axial direction; a shaft that is provided between the filter and the flow straightening plate and that straightens the downstream end of the flow straightening plate according to the wind pressure of the fluid passing through the exhaust passage. An exhaust emission control device for an internal combustion engine, comprising: a stopper that slidably supports the plate in a radial direction. 3. An exhaust gas purification apparatus comprising a filter provided in an exhaust passage of an internal combustion engine and capable of purifying exhaust gas, and heating means for regenerating the filter by burning exhaust gas components collected by the filter. And a rectifying plate which is provided on the filter upstream side of the exhaust passage so as to face the filter upstream end surface, and guides exhaust gas to the filter outer peripheral portion, and supports the rectifying plate slidably in the axial direction. A shaft; an urging means that is inserted into the shaft and urges the rectifying plate to an upstream side; a rotating body that is fixed to the shaft and rotates at a rotation speed according to a flow velocity of a fluid flowing through the exhaust passage; An exhaust gas purification apparatus for an internal combustion engine, comprising: a flyweight that rotates together with the rotating body and moves the straightening vane to a downstream side against the biasing means as the centrifugal force increases. Apparatus.