JP2002332829A - Exhaust emission control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an exhaust emission control device of an internal combustion engine, capable of detecting an accurate engine load, calculating the SOX amount contained in the exhaust gas, determining an SOX poisoning amount of an NOX storage- reduction catalyst, and suitably discriminating the regeneration timing of the NOX storage-reduction catalyst. SOLUTION: This exhaust emission control device comprises the NOX storage- reduction catalyst in an exhaust passage, in the internal combustion engine, an engine load calculating means for calculating engine load, based on upstream-side pressure and downstream-side pressure of a compressor, driven by the internal combustion engine in a refrigeration cycle for circulating and supplying refrigerant to the compressor, an engine speed detecting means, an air-fuel ratio control means, and a calculation means for calculating the exhaust gas amount, from the engine load, the engine speed, and the air-fuel ratio. The exhaust emission control device estimates an SOX toxic amount of the NOX storage-reduction catalyst, due to the passing of a predetermined amount of exhaust gas which pass through the NOX storage-reduction catalyst, and regenerates the NOX storage-reduction catalyst when the estimated SOX poisoning amount reaches the predetermined amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an exhaust passage having NO _X
The present invention relates to an exhaust gas purification device for an internal combustion engine having a storage reduction catalyst.

[0002]

2. Description of the Related Art In an exhaust gas purifying apparatus for an internal combustion engine provided with a conventional NO _X storage reduction catalyst, the engine load is determined from the throttle opening. That is, it has been determined that the engine load is large when the throttle opening is large, and that the engine load is small when the throttle opening is small. However, since the throttle is affected by fluctuations in the atmospheric pressure, it is not always possible to accurately detect the engine load.

[0003]

In the [0006] Therefore, the present invention, to detect a more accurate engine load, determine the SO _X poisoning amount of the NO _X occluding and reducing catalyst to accurately calculate the amount of exhaust gas, _the NO _X storage reduction It is an object of the present invention to provide an exhaust gas purification device for an internal combustion engine, which can appropriately determine the catalyst regeneration time.

[0004]

In order to solve the above-mentioned problems, according to the first aspect of the present invention, NO _{X is provided in} an exhaust passage of an internal combustion engine.
An engine load calculating means for providing an occlusion reduction catalyst and calculating an engine load from a pressure on an upstream side and a pressure on a downstream side of the compressor in a refrigeration cycle for circulating a refrigerant to a compressor driven by the internal combustion engine; a number detection means and the air-fuel ratio control means, the engine load, comprising a calculating means for calculating an exhaust gas quantity from the engine speed and the air-fuel ratio, said by a predetermined amount of exhaust gas passes through the _the NO _X storage reduction catalyst The SO _X poisoning amount of the NO _X storage reduction catalyst is estimated, and when the estimated SO _X poisoning amount reaches a predetermined amount, N
O _X it was to carry out the regeneration of the storage-reduction catalyst. In the invention of claim 2 in the invention of claim 1, it estimates the regeneration speed from the temperature of the NO _X occluding and reducing catalyst, and as the temperature of the NO _X occluding and reducing catalyst becomes enough to set short reproduction time high.
According to a third aspect of the present invention, in the second aspect, there is provided an estimating means for estimating the regeneration speed from the temperature of the NO _X storage reduction catalyst and estimating the total regeneration amount from the regeneration time and the regeneration speed. It is possible to cope with the case where the operating conditions fluctuate. According to a fourth aspect of the present invention, in the second or third aspect, the temperature of the NO _X storage reduction catalyst is controlled by changing the ignition timing.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment of the Invention) FIG.
1 is a system schematic diagram of an internal combustion engine 100 embodying the invention of claims 1 to 4. In the internal combustion engine 100, the air-fuel mixture generated by the mixer 11 is supplied to the internal combustion engine main body 1, burns in a combustion chamber (not shown), and exhaust gas is discharged through an exhaust pipe 13 (exhaust passage). NO _{X in} the middle of the exhaust pipe 13
An occlusion reduction catalyst 14 is provided.

The internal combustion engine body 1 drives a compressor 7 (compressor) via a belt 15. The compressor 7 is provided with a pipe 33 that includes a condenser 30, an expansion valve 32, and an evaporator 31 and forms a refrigeration cycle 50 in the middle. A refrigerant (not shown) circulates in the refrigeration cycle 50.

As shown in FIG. 1, a pressure sensor 4 is provided on a pipe 33 on the upstream side of the compressor 7, and a pressure sensor 5 is provided on a downstream side. The pressure sensors 4 and 5 can transmit detection signals to the CPU 2 via signal lines 21 and 22, respectively.

The CPU 2 calculates the engine load Pe by the equation (1) based on the detection signals input from the pressure sensors 4 and 5.

(Equation 1) Here, P ₁ is the upstream pressure of the compressor 7, and P ₂ is the compressor 7
, C is a coefficient, and k is a specific heat ratio of the refrigerant.

Air is supplied to the mixer 11 through a pipe 19. Fuel is supplied to the mixer 11 from the fuel tank 9 via a pipe 20 provided with an air-fuel ratio control valve 10 in the middle.

The air-fuel ratio of the air-fuel mixture in the mixer 11 can be changed by adjusting the opening of the air-fuel ratio control valve 10. For example, when the opening is increased, a large amount of fuel is supplied, so that the air-fuel ratio is reduced. Conversely, when the opening is reduced, the air-fuel ratio is increased. The opening of the air-fuel ratio control valve 10 is CP
It can be changed by a signal (command) transmitted from U2.

The internal combustion engine body 1 is provided with an engine speed detecting device 3, and a detection signal detected by the engine speed detecting device 3 is transmitted to the CPU 2 via a signal line 23. I have.

When the internal combustion engine 100 is operating normally, the air-fuel ratio λ is set to lean (lean).
Therefore, the opening of the air-fuel ratio control valve 10 is set to be small. The value of the air-fuel ratio λ is known by the CPU 2, and the fuel flow rate is determined based on the engine speed and the engine load.
U2 is calculated.

[0013] The fuel flow rate changes regardless of the engine speed, the engine load, or the air-fuel ratio. Ones in the exhaust gas, the fuel flow rate proportional to trace sulfur component (SO _X) includes a sulfur component flowing into _the NO _X storage reduction catalyst 14, which are all accumulated in the _the NO _X storage reduction catalyst 14 Assume that When the sulfur component is accumulated in the NO _X storage reduction catalyst 14, the NO _X storage capacity is reduced, and the function as a catalyst is reduced.

When the fuel flow rate is known, the NO _X storage reduction catalyst 1
The amount of poisoning by the sulfur component of No. 4 can also be calculated. When this poisoning amount reaches a predetermined amount set in advance, the NO _X storage reduction catalyst 14 is regenerated. That is, CPU
2, a signal is transmitted to the air-fuel ratio control valve 10, the opening degree of the air-fuel ratio control valve 10 is increased, and the air-fuel ratio λ is set slightly richer than λ = 1.0 (the stoichiometric air-fuel ratio). The exhaust temperature is desirably set to 600 ° C. or higher, and the operation is performed for a predetermined time under these conditions.

[0015] Thus, NO attached to _X occluding and reducing catalyst 14 sulfur component was (poisoned) is removed, to return _the NO _X storage capacity of the NO _X occluding and reducing catalyst 14 to the capacity before sulfur poisoning component Can be.

FIG. 2 shows the fuel flow rate calculated from the engine load / engine speed and the air-fuel ratio of the internal combustion engine 100 and the poisoning speed and the poisoning speed of the NO _X storage reduction catalyst 14 when the internal combustion engine 100 is performing the storage operation. It is a graph which shows an example of a temporal change of the poisoning amount by a sulfur component.

As shown in the graph of FIG. 2, the fuel flow rate decreases between the time t ₆ of time t _7, since the total amount of SO _X contained in the exhaust gas is decreased, of the NO _X occluding and reducing catalyst 14 The poisoning rate is slow, and the SO _X poisoning amount during this period has not increased much. However, when the fuel flow rate after time t ₇ is increased than the time t ₆ before than the time t ₆ before been an increase in the total amount of SO _X contained in the exhaust gas poisoning speed Hayamari, resulting, SO _X It can be seen that the poisoning amount has also increased.

(Embodiments of Claims 2 and 3) FIG.
5 is a graph showing the relationship between the regeneration speed of the NO _X storage reduction catalyst 14 and the temperature. FIG. 4 is a graph showing the temperature distribution of the exhaust gas depending on the level of the engine load and the engine speed. Further, FIG. 5, _the NO _X storage in time of reduction catalysts 14 effects operation for reproducing the playback speed and sulfur of the catalyst temperature and _the NO _X storage reduction catalyst 14 estimated from the engine load and the engine speed of the internal combustion engine 100 It is a graph which shows the time-dependent change of the poisoning amount by a component.

As shown in FIG. 3, the reproduction speed increases as the temperature rises (conversely, it decreases as the temperature decreases). When the engine load / engine speed decreases, the temperature of the exhaust gas decreases, so that the temperature of the NO _X storage reduction catalyst 14 also decreases.

[0020] Thus, in between time t ₈ in Figure 5 at time t _9, the catalyst temperature (exhaust gas temperature) is lowered by the engine load and the engine speed drops, it drops playback speed of the NO _X occluding and reducing catalyst 14 and, also, regeneration amount (decrease amount of the sulfur component) is leveled off (i.e., nO _X occluding and reducing catalyst 14 does not proceed reproduced by a temperature drop of, poisoning amount changes little) of the apparent .

[0021] Thus, the operating state of the internal combustion engine 100 (engine load and engine speed) reproduction speed is changed by the variation, NO _X occluding and reducing catalyst 14 time required to completely eliminate the sulfur components from ( (Reproduction time) fluctuates.

Therefore, the extent to which the regeneration speed is affected by variations in engine load and engine speed is investigated in advance, and a map is created from the survey results. As the engine load and the engine speed fluctuate during the regeneration operation of the internal combustion engine 100, the regeneration speed is obtained from this map, the integrated value of the regeneration amount is calculated by the CPU 2, and when the integrated value reaches the poisoning amount, Stop regeneration operation and switch to normal operation.

FIG. 6 is a graph showing the relationship between the temperature of the exhaust gas and the ignition timing. FIG.
As can be seen from FIG. 5, the exhaust gas temperature becomes higher as the ignition timing becomes later. When the engine load and the engine speed decrease, the exhaust temperature also decreases. However, the exhaust temperature can be increased by delaying the ignition timing.

[0024] Therefore, even when the engine load and the engine speed is decreased, it is possible to ensure the temperature of the NO _X occluding and reducing catalyst 14 required for reproduction by delaying the ignition timing.

[0025]

According to the first aspect of the present invention, the pressure sensors 4 and 5 are installed on the pipe 33 in the refrigeration cycle 50 on the upstream and downstream sides of the compressor 7 (compressor), respectively.
Since the engine load Pe is calculated from the equation (1) based on the pressures P ₁ and P ₂ detected by the pressure sensors 4 and 5, the engine load Pe is calculated more accurately than is obtained from the throttle opening as in the conventional case. be able to.

[0026] Thus, it is possible to accurately calculate the fuel flow rate by being able to accurately calculate the engine load, the sulfur poisoning amount of the NO _X occluding and reducing catalyst 14 can be accurately grasped.

[0027] In the second aspect of the present invention estimates the playback speed from the temperature of the NO _X occluding and reducing catalyst 14, since the higher the playback time temperature increases of the NO _X occluding and reducing catalyst 14 is set to be shorter, _the NO _X storage reduction The regeneration of the catalyst 14 can be suppressed to a necessary minimum, and the thermal efficiency in the entire operation of the internal combustion engine 100 can be improved.

According to the third aspect of the present invention, since the total regeneration amount is estimated from the regeneration speed and the regeneration time of the NO _X storage reduction catalyst 14, even if the engine load or the engine speed fluctuates, the integrated value of the regeneration is obtained. Can be accurately estimated, and the regeneration operation time can be minimized.

[0029] In the invention of claim 4, even lower than the temperature of the NO _X occluding and reducing catalyst 14 low engine load and engine speed a minimum temperature required for regeneration, to ensure a minimum temperature by retarding the ignition timing And the time required for reproduction can be reduced.

[Brief description of the drawings]

FIG. 1 is a system schematic diagram of an internal combustion engine embodying the invention of claims 1 to 4.

FIG. 2 shows changes over time in the fuel flow rate calculated from the engine load / engine speed and the air-fuel ratio of the internal combustion engine, the poisoning rate of the NO _X storage reduction catalyst, and the poisoning amount due to the sulfur component during the storage operation. 5 is a graph showing an example of the above.

FIG. 3 is a graph showing the relationship between the regeneration speed of the NO _X storage reduction catalyst and the temperature.

FIG. 4 is a graph showing the temperature distribution of exhaust gas depending on the engine load and the engine speed.

[5] In when performing an operation for reproducing _the NO _X storage reduction catalyst, the engine load, the catalyst temperature calculated from the engine speed, _the NO _X storage reduction playback speed and time of the poisoning amount of the sulfur component of the catalyst It is a graph which shows an example of a change.

FIG. 6 is a graph showing a relationship between exhaust gas temperature and ignition timing.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 internal combustion engine main body 2 CPU (estimating means) 3 engine speed detecting device 4, 5 pressure sensor 7 compressor (compressor) 9 fuel tank 10 air-fuel ratio control valve (air-fuel ratio control means) 11 mixer 13 exhaust pipe (exhaust passage) 14 NO _X storage reduction catalyst 30 Condenser 31 Evaporator 32 Expansion valve 33 Piping 50 Refrigeration cycle 100 Internal combustion engine

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 41/04 330 F02D 41/04 330C 45/00 314 45/00 314Z F02P 5/15 F02P 5/15 B (71) Applicant 000221834 Toho Gas Co., Ltd. 19-18 Sakurada-cho, Atsuta-ku, Nagoya-shi, Aichi (72) Inventor 72) Inventor Toru Nakazono 1-32 Chaya-cho, Kita-ku, Osaka-shi, Osaka Inside Yanmar Diesel Co., Ltd. (72) Inventor Hirokazu Sasaki 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka (72) Inventor Kota Yokoyama 4-1-2, Hirano-cho, Chuo-ku, Osaka-shi, Osaka Prefecture Inside Osaka Gas Co., Ltd. (72) Inventor Toru Matsui Minato-ku, Tokyo 1-5-20 Kishi Tokyo Gas Co., Ltd. (72) Inventor Masaki Honmichi 1-5-20 Coast, Minato-ku, Tokyo Tokyo Gas Co., Ltd. (72) Inventor Yoshihito Taniguchi Sakurada, Atsuta-ku, Nagoya City, Aichi Prefecture Town No.19-18 Toho Gas Co., Ltd.F-term (reference)

Claims (4)

[Claims] 1. A provided _the NO _X storage reduction catalyst in an exhaust passage of an internal combustion engine, from the upstream pressure and downstream pressure of the compressor in the circulation supplying the refrigeration cycle refrigerant to the compressor driven by the internal combustion engine An engine load calculating means for calculating an engine load; an engine speed detecting means and an air-fuel ratio control means; a calculating means for calculating an exhaust gas amount from the engine load, the engine speed and the air-fuel ratio; gas and SO _X poisoning amount of the _the NO _X storage reduction catalyst is estimated by passing through the _the NO _X storage reduction catalyst, SO _X poisoning amount that the estimated regeneration of the NO _X occluding and reducing catalyst reaches a predetermined amount An exhaust gas purifying apparatus for an internal combustion engine, characterized in that it is performed. Wherein _the NO _X storage reduction temperature from estimating the playback speed of the catalyst, the exhaust gas purification system of an internal combustion engine according to claim 1 in which the temperature of the NO _X occluding and reducing catalyst becomes enough to set short reproduction time high. 3. The exhaust gas purifying apparatus for an internal combustion engine according to claim 2, further comprising estimating means for estimating the regeneration speed from the temperature of the NO _X storage reduction catalyst and estimating the total regeneration amount from the regeneration time and the regeneration speed. 4. The exhaust gas purifying apparatus for an internal combustion engine according to claim 2, wherein the temperature of the NO _X storage reduction catalyst is controlled by changing the ignition timing.