JP3246151B2 - Diesel engine exhaust purification system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exhaust gas purifying apparatus for a diesel engine capable of efficiently burning and removing particulates collected by a filter.

[0002]

2. Description of the Related Art Exhaust gas discharged from a diesel engine contains particulates. Therefore, in order to collect the particulates, a filter for collecting the particulates is provided in an exhaust passage of the diesel engine (see FIG. 1 described later).

The above-mentioned filter is, for example, a honeycomb body made of a porous member, and has a large number of flow paths for introducing and discharging exhaust gas. An oxidation catalyst such as Pt or Pd for burning and removing the collected particulates is carried on the microporous wall provided between the flow paths. The filter is always disposed in the exhaust system path, is regenerated by burning and removing the collected particulates, and is used repeatedly by collecting and regenerating.

As a method of regenerating the filter, the exhaust gas temperature is raised to a temperature higher than the particulate combustion temperature by reducing the valve opening of an intake throttle valve provided upstream of the diesel engine. A removal method has been proposed (Japanese Patent Laid-Open No. 57-1).
79348). According to this method, the temperature of the exhaust gas can be increased, the particulates can be removed by burning, and the filter can be regenerated with a simple structure.

[0005]

However, in the above-mentioned conventional method, the aim is only to raise the temperature of the exhaust gas to a high temperature (for example, 400 ° C.) required for burning and removing the particulates. For this reason, if the intake throttle valve is simply excessively throttled in order to raise the exhaust gas temperature, the fuel consumption is deteriorated and the emission is significantly deteriorated (the explanation in the first embodiment described later and FIGS. 2 and 3). reference).

The present invention has been made in view of the above-mentioned conventional problems, and an exhaust gas purifying apparatus for a diesel engine capable of efficiently burning and removing particulates and regenerating a filter without deteriorating fuel consumption and emission. It is something to offer.

[0007] The present invention comprises a catalyst with a filter for collecting particulates in interposed in an exhaust passage of a diesel engine exhaust gas, and the operating condition detecting means for detecting an operating condition of de I over diesel engine, the filter over and heating means for raising to the combustion temperature of the particulate temperature, and collection amount calculating unit for calculating the amount of collected particulates captured in full Iruta, Shin from the collection amount calculating section
Signal and the signal from the operating state detection means.
Dust collection amount and operation status of diesel engine
A temperature raising control section for operating the temperature raising means according to the state.
Diesel exhaust gas purifying equipment
The heating means is the fuel that supplies fuel to the diesel engine.
Low intake air consisting of a supply device and an intake throttle valve or exhaust throttle valve
Means for reducing the temperature, and the temperature raising control section
The engine load detected by the state detection means is medium rotation, medium load
The boundary between the area B and the area A with low rotation and low load is K1,
The boundary between the area B and the high-speed, high-load area C is K2
Relatively high rotation on the side close to the area C in the area B,
When the boundary with the high load area B ′ is K3,
The area B in which the gin load is between the boundaries K1 and K2.
Only when it is located in
At this time, and at this time, the engine load is
In the case of the above-mentioned region B ′ between the boundary 3 and the boundary K2,
Operate only the above fuel supply device to raise the temperature of the filter.
And the engine load is equal to the boundary K3 in the region B.
If it is between the boundary K1, the fuel supply device and the intake low
Operate both reducing means to raise the temperature of the filter,
Depending on the amount of particulates collected on the
Is an exhaust gas purifying apparatus for a diesel engine , wherein a filter is continuously regenerated .

[0008] It should be most noticeable in the present invention, above
Focusing on the boundaries K1, K2, and K3, the engine load is K
Heating means only in the region B between 1 and K2
To raise the temperature of the filter.
When the load is in the B 'region between K3 and K2,
Operate the fuel supply to raise the temperature of the filter,
Fuel supply when engine load is between K3 and K1
The temperature of the filter is raised by operating both the device and the intake reduction unit
Depending on the amount of particulates collected on the filter.
That is, the filter is regenerated .

The temperature increase control section is configured to operate the temperature increase section in accordance with the collection amount and the operating condition of the diesel engine, based on signals from the collection amount calculation section and the operating state detecting means. You. As a result, it is possible to perform more appropriate particulate combustion removal and filter regeneration according to the operating conditions of the diesel engine (low rotation speed, low load, up to high rotation speed, high load) as described later.

[0010] As the temperature raising means, there is an intake throttle valve for introducing air into a diesel engine. In this case,
The exhaust gas temperature is increased by reducing the opening degree of the intake throttle valve. That is, the exhaust gas temperature is increased by reducing the amount of air introduced into the diesel engine. The larger the throttle amount of the intake throttle valve, the higher the exhaust gas temperature.

Further, as a temperature raising means, there is an exhaust throttle valve provided in an exhaust pipe behind the filter. Also in this case, the temperature of the exhaust gas is increased by reducing the opening degree of the exhaust throttle valve. That is, the exhaust gas temperature is raised by reducing the amount of exhaust gas coming out of the filter. The larger the throttle amount of the exhaust throttle valve, the higher the exhaust gas temperature. And the above intake throttle valve or waste throttle valve
Constitutes intake reduction means.

Further, as a heating means, there is a fuel supply device for supplying fuel to a diesel engine. Examples of the fuel supply device include an injection amount increasing device and a fuel injection retarding device. The above-described injection amount increasing device is a device for increasing the amount of fuel supplied to the diesel engine as compared with the case of normal operation.

The fuel injection retarding device is a device for delaying (retarding) the timing of injecting fuel into the diesel engine as compared with the case of normal operation. The injection amount increasing device and the fuel injection retarding device are usually operated by a controller of the fuel injection valve. In addition, the exhaust gas temperature increases as the fuel increases and the retard angle increases.

The trapping amount calculating section calculates the trapping amount of the particulates based on signals from the differential pressure detecting means and the operating state detecting means. The differential pressure detecting means detects a pressure difference between before and after the filter. As the amount of particulates collected in the filter increases, the pressure difference increases.

The operating condition detecting means detects the engine speed and the load condition of the diesel engine. Therefore, the trapping amount is calculated based on the detection values from the differential pressure detecting means and the operating state detecting means. And
The signal of the trapping amount is sent to the temperature raising control unit.

The temperature raising control section operates the temperature raising means according to the trapped amount to raise the temperature of the exhaust gas. As an example of a method of increasing the exhaust gas temperature, in the case of an intake throttle valve, the valve opening degree is set in a two-stage system (FIG. 3), a multi-stage system (FIG. 8), and a continuous system (stepless system, FIG. 9). ), The temperature can be increased in accordance with each stage method. This can also be achieved by operating the injection amount increasing device and the fuel injection retarding device in a stepwise manner as described above.

Further, the above-mentioned heating means is not limited to one kind,
For example, the intake throttle valve and the injection amount increasing device or the fuel injection retarding device, the injection amount increasing device or the fuel injection retarding device and the exhaust throttle valve, and the like may be operated in combination. As a result, the fuel efficiency and emission of the diesel engine can be further improved, and the particulate combustion can be more effectively removed.

Further, it is preferable that the temperature increase control section has an exhaust gas temperature sensor for detecting a temperature of the exhaust gas. As a result, at low temperatures immediately after the start of the diesel engine,
Even during a high-load operation, it is possible to accurately determine whether or not it is necessary to operate the temperature raising means for removing and burning the particulates. Therefore, it is possible to avoid the operation of removing and burning particulates, which is originally impossible at the low temperature, and to improve the fuel efficiency and emission.

[0019]

In the exhaust gas purifying apparatus for a diesel engine according to the present invention, the particulates in the exhaust gas of the diesel engine are sequentially collected and deposited by the above-mentioned filter. So, for example, the entrance of the filter
The differential pressure signal of the filter in the differential pressure detecting means for detecting the differential pressure between the pressure and the outlet, and the signal from the operating state detecting means,
The collection amount calculation unit calculates the collection amount.

When the trapping amount has reached an amount necessary for filter regeneration, the temperature-raising control section operates the temperature-raising means in a stepwise or continuous manner in accordance with the trapping amount, thereby reducing exhaust gas. The temperature is raised above the burning temperature of the particulates to burn off the particulates.

If the pressure difference in the differential pressure detecting means decreases as the combustion removal proceeds, the combustion removal is completed, and the operation of the temperature raising means is stopped. By these operations, the burning and removal of the particulates, that is, the regeneration of the filter is completed.

The operation timing of the temperature raising means is related to the trapped amount. Therefore, the set value of the trapping amount that needs to be removed by combustion is determined in advance by an experiment or the like. When the exhaust gas temperature is raised not only to one but also to the two-stage system and the multi-stage system as described above, there are a plurality of values corresponding thereto. Further, in the case of the continuous system, after the temperature reaches a certain set value, the temperature increasing means is gradually operated to complete the combustion removal.

As described above, according to the present invention, not only the differential pressure in the filter but also the trapped amount is detected.
The heating means is operated in multiple stages. As a result, the diesel engine can avoid an excessive operation of the temperature raising means as compared with the case of the particulate combustion removal by the conventional method, and can maintain a favorable operation state. Therefore, there is no deterioration in fuel consumption and emission during combustion removal.

Further, when the temperature raising control section is operated in accordance with the collection amount and the operating conditions based on the signals from the collection amount calculating section and the operating state detecting means, the fuel consumption and the emission are further improved. , Filter regeneration can be performed. That is, the temperature raising control section raises the temperature of the exhaust gas in accordance with the collection amount and the operating condition of the diesel engine based on the signals from the trapping amount calculating section and the operating state detecting means. (See Examples). The operating conditions include, for example, a low-speed, low-load area A, a medium-speed, medium-load area B, a high-speed, high-load area C shown in FIG. And especially
In the following description, among the areas A, B, and C,
In the area B ', where the rotation is relatively high and the load is relatively high
Attention should be paid to the area between the above boundaries K1, K2, and K3.
Therefore, various kinds of temperature raising operations are performed. That is, the book
According to the invention, the engine load is relatively large in the region B.
In the region B 'between K3 and K2, only the fuel supply device is used.
To regenerate the filter. That
Therefore, there is no emission deterioration. If B '
If the intake air volume is reduced in the
When the filter temperature rises, emission deteriorates.
In other words, when the intake air volume is reduced, the exhaust gas temperature rises,
The molecular weight of the gas drawn into the engine cylinder is reduced
Therefore, the amount of heat received per molecule of the suction gas increases.
Therefore, the peak temperature in the cylinder when the fuel burns
Get higher. As a result, the amount of generated NOx increases.
You. This phenomenon is due to the heavy load of the diesel engine,
It increases sharply as the amount of fuel burned increases. The present invention
Has been eliminated. On the other hand, in region B,
In the region between K3 and K2 where the load is relatively small, NO
x hardly increases and the engine load is relatively small
No. Therefore, it is necessary to raise the filter temperature significantly.
If there is, both the fuel supply device and the intake reduction means
Operation to make sure that the temperature of the filter rises.
Perform playback.

Therefore, according to the present invention, it is possible to provide an exhaust gas purifying apparatus for a diesel engine capable of efficiently burning and removing particulates and regenerating a filter without deteriorating fuel consumption and emission.

[0026]

【Example】

Embodiment 1 An exhaust gas purifying apparatus for a diesel engine according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the exhaust gas purifying apparatus of this embodiment includes a filter 12 provided with a catalyst and interposed in an exhaust pipe 17 of a diesel engine 11 for trapping particulates in exhaust gas, and an inlet and an outlet of the filter 12. Differential pressure detecting means 15 for detecting the differential pressure of the engine, and diesel engine operating state detecting means 16
And an intake throttle valve 13 as a temperature raising means for raising the temperature of the exhaust gas introduced into the filter 12 to the combustion temperature of the particulates. Diesel engine 1
An intake pipe 10 is provided on the upstream side of 1.

The differential pressure detecting means 15, the operating state detecting means 16, and the intake throttle valve 13 are electrically connected to an ECU (central control unit) 14. Also, this ECU
A collection amount calculation unit 141 for calculating a collection amount of particulates collected by the filter based on signals from the differential pressure detection unit 15 and the operation state detection unit 16; and a collection amount calculation unit. A temperature raising control unit 142 that operates the intake throttle valve 13 as the temperature raising means in a stepwise manner in accordance with the trapping amount and the operating conditions in accordance with a signal from the 141 and the operating state detecting means 16.

That is, the exhaust pipe 1 of the diesel engine 11
In the middle of 7, a filter 12 with an oxidation catalyst for collecting particulates in exhaust gas is provided. The filter 12 has a large number of flow paths formed by a honeycomb lattice made of a porous material such as ceramic.
The inlet and outlet of the flow path are alternately plugged with a sealing material. Further, a coating layer of γ-alumina or the like is provided on the surface of the porous member, and Pt,
An oxidation catalyst such as Pd or Cu is supported.

Further, there are provided a differential pressure detecting means 15 for detecting a pressure difference between before and after the filter 12, and an operating state detecting means 16 for detecting the rotational speed and load of the diesel engine 11.
Then, based on the outputs from the differential pressure detecting means 15 and the operation state detecting means 16, the trapping amount calculation unit 141 calculates the trapping amount of the particulates in the filter 12, and when the trapping amount exceeds the set value. Next, an actuator (not shown) is operated based on a command from the temperature raising control unit 142 in the ECU 14 to reduce the valve opening of the normally open butterfly type intake throttle valve 13 provided in the intake pipe 8.

Next, the operation and effect of this embodiment will be described.
In the exhaust gas purification apparatus configured as described above, if particulates are trapped in the filter 12, clogging occurs, so that the differential pressure across the filter 12 detected by the differential pressure detecting means 15 increases. On the basis of the output of the differential pressure detecting means 15 and the output of the operating state detecting means 16, the trapping amount calculating section 141 calculates the trapping amount of the particulates in the filter 12.

When the trapping amount exceeds a set value at which particulate combustion is required to be removed, the intake throttle valve 13 is throttled. When the intake throttle valve 13 is throttled, the temperature of the exhaust gas discharged from the diesel engine 11 rises, so that the particulates on the filter 12 are burnt and removed by oxidative combustion.
Is played.

However, at this time, the intake throttle valve is simply
If the throttle is excessively reduced as in the conventional example, the output of the diesel engine decreases, and as shown in FIG. 2, the emission is greatly deteriorated in addition to the fuel consumption (fuel consumption). In particular, conventionally, as shown in FIG.
When the set value m1 (for example, 20 g), which is a large amount of trapping, is exceeded, the intake throttle valve is made large (for example, 50%) at a time.
The filter 12 was reproduced by squeezing (dotted line in FIG. 3).
As a result, fuel economy and emissions deteriorated significantly (Fig. 2).

On the other hand, in the present embodiment, the intake throttle valve is throttled in consideration of the amount of trapped particulates, and as shown in FIG.
The first set value m2 (for example, 1 <2
0 g), the intake throttle valve is made smaller (for example, 2 g).
5%) Regenerate the filter 12 by squeezing.

At this time, if the filter 12 cannot be regenerated in this state, the trapping amount increases, and the second set value m1
If it exceeds (for example, 20 g), the intake throttle valve is reduced by a conventional amount (for example, 50%). That is, in this example, by controlling the throttle amount of the intake throttle valve in accordance with the trapped amount of particulates, deterioration of fuel efficiency and the like is minimized, and the filter 12 is reliably and efficiently installed. It can be played.

Next, the operation of the intake throttle valve in the exhaust gas purifying apparatus will be described with reference to the flowchart shown in FIG. In this flowchart, the case where the throttle amount of the intake throttle valve is controlled according to the operating conditions of the diesel engine in response to the signal from the operating state detecting means 16 is shown.

First, in S (step) 101,
From the differential pressure signal from the differential pressure detecting means 15 and the operating condition reading signal of the diesel engine (E / G) from the operating state detecting means 16, the trapping amount calculation unit 141 calculates the trapping amount of particulates. . In S102, it is determined whether or not the trapping amount m is larger than the first set value m2. If it is smaller, the process returns to S101. on the other hand,
When the trapping amount m is larger than the above-mentioned m2, the process proceeds to S103, and the throttle amount of the intake throttle valve is controlled according to the operating conditions of the diesel engine.

That is, when the operation condition of the diesel engine 11 is low rotation and low load (A region in FIG. 5), the exhaust gas temperature is low, for example, 250 ° C. or less. Therefore, it is difficult to raise the exhaust gas temperature to the particulate combustion temperature by restricting the intake throttle valve while suppressing deterioration of fuel efficiency and the like. In addition, the amount of particulates discharged is small at low rotation and low load. Therefore, regeneration of the filter is postponed. Therefore, in the flowchart, S10
Then, the flow shifts from S3 to S1042, where the above-mentioned aperture is not performed.

On the other hand, when the diesel engine is running at a high speed and a high load (region C in FIG. 5), the exhaust gas temperature becomes, for example, 4
The temperature is as high as 00 ° C or higher, and is higher than the burning temperature of particulates. Therefore, there is no need for any further heating operation.
No intake throttle is performed. Therefore, in the flowchart, S
The process proceeds from S103 to S105 via S1043.

When the diesel engine is rotating at medium speed and medium load (region B in FIG. 5), the amount of particulates discharged is relatively large, and the exhaust gas temperature is not high as in the case of high speed and high load. Therefore, S10 of the flowchart
The process proceeds from S3 to S1041, and the intake throttle valve is reduced by the throttle amount a. A, B, C in the flowchart of FIG.
Indicates areas A, B, and C under the above-mentioned operating conditions.

Then, in S105, the above-described S10
The trapping amount is calculated in the same manner as in step 1. In step S106, the trapping amount m <m0 (m0 is, for example, 0.5 g), and when it is determined that the particulates have been burnt and removed,
Proceeding to 112, the intake throttle valve 13 is fully opened (throttle amount = 0), and the regeneration is terminated. In S106, the collected amount is m
If not <m0, the process proceeds to S107, and it is determined whether the trapping amount m is equal to or more than the second set value m1 (large collecting amount). If the trapped amount m is not more than the set value m1, the cycle of returning to S103 is repeated.

On the other hand, if the collected amount m is equal to or more than m1, the process proceeds to S108 because the collected amount is large, and again returns to S1.
The operating condition is detected by the operating state detecting means in the same manner as shown in FIG. Then, the area A (low rotation,
In the case of (low load), the flow shifts to S1092, where the intake throttle valve is not throttled. If the operating condition is the region C (high rotation, high load) in FIG. 5, the flow shifts to S1093, and shifts to S110 without throttling the intake throttle valve.

The operating conditions are as shown in the area B (medium rotation,
In the case of (medium load), the flow shifts to S1091, where the intake throttle valve is set to a larger throttle amount b. As a result, the temperature of the exhaust gas is further increased, and the combustion is removed. And
In S110, the collection amount is calculated in the same manner as in S101. If the collection amount is not m <m0 in S111, the cycle of returning to S108 is repeated. On the other hand, if the trapping amount m <m0 in S111, the burning and removal of the particulates have been completed, and the process proceeds to S112.
With the throttle amount of the intake throttle valve set to zero, the collection of particulates is continued again.

Next, as can be seen from the description of the flowchart, whether or not the filter 12 can be regenerated by burning the particulates depends on the operating conditions (rotational speed, load) of the diesel engine at that time and the exhaust gas temperature. It is determined as shown in FIG. That is, in the upper right range from F1 in FIG. 6, the exhaust temperature is high due to high rotation and high load as in the region C in FIG. 5, and natural regeneration of the filter 12 is possible. However, compared to the entire range of use of the diesel engine, the range at the upper right of F1 is narrow. Therefore, it cannot be expected that the filter 12 will be regenerated by relying only on the case where the operating conditions fall within this range in normal operation.

Therefore, when the intake throttle valve is reduced by the throttle amount a as described above (S1041 in the flowchart of FIG. 4),
The exhaust gas temperature rises. Therefore, the reproducible range of the filter 12 is expanded not only to F1 in FIG. 6 but also to F2. In normal operation, the diesel engine changes from a high load to a low load.
It is highly probable that it will be in the upper right area than 2. In this state,
Since the exhaust temperature is high, regeneration of the filter 12 can be sufficiently expected. Moreover, since the throttle amount of the intake throttle valve is small,
There is almost no deterioration in fuel efficiency.

However, if only low-load operation (the area at the lower left of F2 in FIG. 6) continues for a long time, the regeneration of the filter 12 cannot be completed because the exhaust gas temperature does not rise, and particulate collection is not performed. The amount exceeds the second set value m1 (S107 in the flowchart of FIG. 4). Therefore, only at this time, the intake throttle valve is further reduced to the throttle amount b (S1091 in the flowchart of FIG. 4).

As a result, the reproducible range of the filter is expanded to the upper right area of F3 in FIG. Also in this case, similarly to the case of FIG. 5, it is determined whether or not the intake throttle valve is throttled according to the operating conditions. However, the exhaust gas temperature has risen by restricting the intake air.
The judgment is made based on FIG. 7 in which the B and C areas are enlarged as compared with FIG.

As described above, according to the present embodiment, it is possible to avoid the deterioration of fuel efficiency and the like due to the conventional excessive intake throttle and to perform the regeneration of the filter reliably. In many cases, the amount of trapped particulates in the filter is equal to or less than the first set value m2 for starting regeneration (conventionally, only m1, but m2 <m1). Therefore, the average trapping amount is smaller than before. As a result, the back pressure of the diesel engine is reduced, and fuel efficiency during particulate collection is improved.

Furthermore, since the heat generated during the particulate combustion is reduced, the filter can be prevented from being exposed to an excessively high temperature, and the durability of the catalyst and the filter is greatly improved. In the above,
FIG. 3 shows an example in which the throttle amount of the intake throttle valve is changed in two stages. However, the throttle amount, that is, the exhaust gas temperature, may be multi-steps of three or more steps as shown in FIG. 8 or may be stepless (continuous) as shown in FIG.

Embodiment 2 In this embodiment, as shown in FIG. 10, the exhaust pipe 17 is provided with an exhaust throttle valve 130 as a temperature raising means. The exhaust throttle valve 130 is electrically connected to a temperature raising control unit provided in the ECU 14. That is, in this embodiment, the exhaust throttle valve 1 is used as a temperature raising means instead of the intake throttle valve 13 in the first embodiment.
30 is used. In this example, the filter is reproduced in the same manner as in the flowchart (FIG. 4) shown in the first embodiment. In this embodiment, the same effect as in the first embodiment can be obtained.

Embodiment 3 In this embodiment, as shown in FIGS. 11 and 12, instead of the intake throttle valve of Embodiment 1, an injection amount increasing device 131 is used as a temperature increasing means.
Is used. The injection amount increasing device 131 includes an ECU
14 is electrically connected to a temperature raising control unit. The injection amount increasing device 131 uses an electronic fuel injection device. By increasing the valve opening, the amount of fuel supplied to the diesel engine can be increased. As a result, the temperature of the exhaust gas is raised to regenerate the filter.

In this example, the filter is regenerated by controlling the injection amount increasing device according to the flowchart shown in FIG. The figure shows the fuel increase amount a, b or zero by the injection amount increase device (S3041 to 3043, and S30
91 to 3093), and in the case of m <m0 in S306, the process proceeds to S312 and the amount of increase is zero, except that it is the same as the flowchart of FIG. 4 are omitted for the same steps as in FIG. 4 (the same applies hereinafter).

The presence / absence of the above-described fuel increase is the same as the presence / absence of the throttle amount of the intake throttle valve in the first embodiment. The operation of the injection amount increasing device is performed according to the particulate trapping amount and the operating condition of the diesel engine based on the signal from the temperature raising control unit as in the first embodiment. Others are Example 1.
Is the same as In this embodiment, the same effect as in the first embodiment can be obtained.

Fourth Embodiment In this embodiment, as shown in FIGS. 13 and 14, a fuel injection retarding device 132 is used as a temperature raising means instead of the injection amount increasing device 131 of the third embodiment. Fuel injection retarding device 1
By retarding the fuel injection timing by 32, the exhaust gas temperature is raised and the filter is regenerated.

The fuel injection retarding device 132 is a device for retarding the injection timing in the electronic fuel injection device.
In this example, the filter is regenerated by controlling the fuel injection retarding device 132 according to the flowchart shown in FIG. The figure shows the retard amounts a and b by the fuel injection retard device.
Or zero (S4041-4043 and S4091-S
4093), and if m <m0 in S406, S4
12 is the same as the flowchart in FIG. 4 except that the amount of retard is set to zero. The reference numerals are omitted for the same steps as those in FIG.

The presence or absence of the fuel injection retard amount is determined in the first embodiment.
Is the same as the presence or absence of the throttle amount of the intake throttle valve. The operation of the fuel injection retarding device is performed in accordance with the amount of trapped particulates and the operating conditions of the diesel engine in accordance with a signal from the temperature raising control unit as in the first embodiment. Others
This is similar to the first embodiment. In this embodiment, the same effect as in the first embodiment can be obtained.

Embodiment 5 In this embodiment, as shown in FIGS. 15 to 18, an intake throttle valve 13 and a fuel injection retarding device 132 are combined as a temperature raising means. In this embodiment, the determination as to whether or not to activate the temperature raising means uses FIG. 17 instead of FIG. 5 and FIG. 18 instead of FIG. That is, FIG.
Is obtained by dividing the region B of the middle rotation and the medium load shown in FIG. 5 into two regions, a region B and a region B ′. Region B 'region C (high rotation, high load) region closer to, i.e. Ryo
The region B has a relatively high rotation speed and a high load in the region B. Ma
17 and 18 show the boundary K1 between the regions B and A,
A boundary K2 between the region B and the region C, a region B ′ in the region B,
Is displayed.

Then, a region B 'near high rotation and high load ,
That is, between the boundaries K3 and K2, the injection angle is retarded by the fuel injection retarding device as shown in S5041 and S5091 of the flowchart of FIG. Further, in the area B, between the boundaries K3 and K1 , as shown in S5043 or S5093 in the above flowchart,
The fuel injection retarding device and the intake throttle valve execute the retardation of the injection angle and the throttle amount a or the throttle amount b of the intake throttle valve, respectively.

On the other hand, in the regions A and C, neither the fuel injection retarding device nor the intake throttle valve is operated, and the exhaust gas temperature is not increased as in the first embodiment (S50 in the flowchart).
42, S5044, S5092, S5094). Also,
If m <m0 in S506, the process proceeds to S512, where the aperture amount and the retard amount are set to zero. Others are the same as the first embodiment. According to this embodiment, since the exhaust gas temperature is increased by the intake throttle valve and the fuel injection retarding device, the fuel efficiency can be further improved as compared with the first and fourth embodiments. That is, in this example, the comparison is made in the above-mentioned B region.
In the B 'region between K3 and K2 where the dynamic engine load is large
The filter is regenerated by raising the temperature only with the fuel supply device
Are doing. As a result, emissions do not deteriorate.
No. If the amount of intake air is reduced in the region B ',
And emission when the filter temperature rises due to NOx increase
Will be worse. In other words, when the intake air volume is reduced,
Although the air temperature rises, it is drawn into the cylinder of the engine.
Because the molecular weight of the inhaled gas is reduced,
The amount of heat received increases. Therefore, when fuel burns
The peak temperature in the cylinder increases. As a result, NOx emission
The amount of production will increase. This phenomenon is
The greater the engine load and the more fuel burned, the more rapidly
To increase. This example solves this. On the other hand, B
K3 to K2 where the engine load is relatively small in the region
In the region between the two, there was almost no increase in NOx, and
Load is relatively small. Therefore, increase the filter temperature.
If it is necessary to raise the temperature,
Operating both the air intake reduction means and the filter
The temperature is raised and the regeneration is performed. Further, according to this embodiment, the same effect as that of the first embodiment can be obtained.

Embodiment 6 In this embodiment, as shown in FIGS. 19 and 20, an intake throttle valve 13 and an injection amount increasing device 131 are combined as a temperature raising means. Also in the case of this example, FIG.
7. It is determined based on the areas A, B, B 'and C in FIG.

Then, the area B ' , that is, the boundaries K3 and K2
Between S604 and S604 in the flowchart of FIG.
1, as shown in S6091, the injection amount is increased by the injection amount increasing device. In the area B, the boundary
Between K3 and K2 , S604 of the above flowchart is executed.
As shown in 3 or S6093, the injection amount increasing device and the intake throttle valve execute the injection increase and the throttle amount a or b of the intake throttle valve, respectively.

On the other hand, in the regions A and C, neither the injection amount increasing device nor the intake throttle valve is operated, and the exhaust gas temperature is not increased as in the first embodiment (S60 in the flowchart).
42, S6044, S6092, S6094). Also,
If m <m0 in S606, the process proceeds to S612, where the aperture amount and the increase amount are set to zero. Others are the same as the fifth embodiment. According to this embodiment, the same effects as in the fifth embodiment can be obtained.

Embodiment 7 This embodiment is an example in which an exhaust gas temperature sensor 19 is provided between the diesel engine 11 and the filter 12 in Embodiment 1 as shown in FIGS. 21 and 22. Based on the output of the temperature sensor 19, it is determined whether or not the intake throttle valve 13 is to be throttled during filter regeneration. That is, at the time of regeneration, the exhaust gas temperature is lower than t1 (for example, 250 ° C.) or lower, or t2 (for example, 40
When the temperature is higher than 0 ° C), the heating means is not operated and the intake throttle valve is not throttled.

This is because, at the low temperature, it is difficult to raise the exhaust gas temperature to the particulate combustion temperature by restricting the intake throttle valve while suppressing deterioration in fuel efficiency and the like. On the other hand, when the temperature is higher than t2,
This is because the particulates are burned and removed at that temperature, and it is not necessary to forcibly operate the temperature raising means.

The flowchart of FIG. 22 shows the above flow. That is, when the trapping amount m is larger than the first set value m2, it is determined in S703 whether the exhaust gas temperature t is lower than the set value t1 or higher than the set value t2. <T <t2), S7
In step 041, the exhaust gas temperature is increased by setting the intake throttle valve to the throttle amount a. On the other hand, when t <t1 or t> t2, the flow shifts to S7042 or S7043, and the intake throttle valve is not operated.

If the trapping amount m is larger than the second set value m1, it is determined in S708 whether or not the exhaust gas temperature t is within the range between t1 and t2. Then, the intake throttle valve is set to the throttle amount b. If t <t1, the process proceeds to S7092, and if t> t2, the process proceeds to S7093, and the intake throttle valve is not operated. If m <m0 in step S706, the process advances to step S712 to set the aperture amount to zero. Others are the same as the first embodiment.

According to the present embodiment, the necessity of the operation of the temperature raising means is determined on the basis of the exhaust gas temperature.
The necessity can be determined, and filter regeneration can be performed under more appropriate conditions. Further, the same effect as in the first embodiment can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an exhaust gas purification device according to a first embodiment.

FIG. 2 is a diagram showing a relationship between a throttle amount of an intake throttle valve, an exhaust gas temperature, and a fuel consumption increase rate in the first embodiment.

FIG. 3 is a diagram showing a relationship between a particulate collection amount and a throttle amount of an intake throttle valve in the first embodiment.

FIG. 4 is a flowchart according to the first embodiment.

FIG. 5 is a diagram showing a relationship between a rotational speed of the diesel engine and a load in the first embodiment.

FIG. 6 is a diagram showing a relationship between a rotational speed and a load of a diesel engine and a reproducible range of a filter in the first embodiment.

FIG. 7 is a diagram showing another relationship between the rotational speed of the diesel engine and the load in the first embodiment.

FIG. 8 is a diagram showing a relationship between a trapped amount of particulates and a multi-stage throttle amount of an intake throttle valve in the first embodiment.

FIG. 9 is a diagram showing a relationship between a trapped amount of particulates and a stepless throttle amount of an intake throttle valve in the first embodiment.

FIG. 10 is an explanatory diagram of an exhaust gas purification device according to a second embodiment.

FIG. 11 is an explanatory diagram of an exhaust gas purification device according to a third embodiment.

FIG. 12 is a flowchart in the third embodiment.

FIG. 13 is an explanatory diagram of an exhaust gas purification device according to a fourth embodiment.

FIG. 14 is a flowchart in the fourth embodiment.

FIG. 15 is an explanatory diagram of an exhaust gas purification device according to a fifth embodiment.

FIG. 16 is a flowchart in the fifth embodiment.

FIG. 17 is a diagram showing a relationship between the rotational speed of the diesel engine and the load in the fifth embodiment.

FIG. 18 is a diagram showing a relationship between the rotational speed of the diesel engine and the load in the fifth embodiment.

FIG. 19 is an explanatory diagram of an exhaust gas purification device according to a sixth embodiment.

FIG. 20 is a flowchart in the sixth embodiment.

FIG. 21 is an explanatory view of an exhaust gas purification device according to a seventh embodiment.

FIG. 22 is a flowchart in the seventh embodiment.

[Explanation of symbols]

 11. . . Diesel engine, 12. . . Filter, 13. . . Intake throttle valve, 130. . . Exhaust throttle valve, 131. . . Injection amount increasing device, 132. . . 13. fuel injection retarding device; . . ECU, 15. . . Differential pressure detecting means, 16. . . Operating state detecting means, 19. . . Exhaust temperature sensor,

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI F02D 9/02 341 F02D 9/02 341G 9/04 9/04 E (56) References JP-A-3-233121 (JP, A ) Actual Opening 63-132819 (JP, U) Actual Opening Hei 2-115911 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) F01N 3/02 F02D 9/04 F02D 9 / 02

Claims (4)

(57) [Claims] 1. A is interposed in an exhaust passage of a diesel engine and a catalyst with a filter for collecting particulates in exhaust gases, operating condition detecting means for detecting the operating conditions of the de I over diesel engine, the temperature of the filter over and heating means for raising to the combustion temperature of the particulates, the trapping amount calculating unit for calculating the amount of collected particulates captured in full Iruta, the signal from the collection amount calculation unit, the operation State detection means
Based on the signal from the
Depending on the operating condition of the diesel engine,
Diesel engine having a heating
In the gas purification apparatus, the temperature raising means supplies fuel to the diesel engine.
A fuel supply device and an intake or exhaust throttle valve
Consists of a gas-reduction means, the Atsushi Nobori control unit is detected by the operating condition detecting means
The engine load is medium rotation, medium load area B and low rotation,
The boundary with the low-load area A is K1, the area B is high rotation,
The boundary with the high load area C is K2,
A relatively high rotation and high load area B ′ near the area C
When the boundary of the engine is K3, the engine load is
Only when it is in the area B between K1 and K2,
The temperature of the filter is raised by operating the temperature raising means. At this time, the engine load is reduced by the boundary K3 and the boundary K2.
, The fuel supply
Operate only the device to raise the temperature of the filter.
The load is between the boundary K3 and the boundary K1 in the region B.
In both cases, both the fuel supply and the intake reduction
Operate to raise the temperature of the filter,
Depending on the amount of trapped
An exhaust purification device for a diesel engine, characterized in that the regeneration of luter is performed . 2. The fuel supply device according to claim 1, wherein
An exhaust purification device for a diesel engine, which is a fuel injection retard device. 3. The fuel supply device according to claim 1,
Is the above-mentioned injection amount increasing device.
Exhaust gas purification device for Zel engine. 4. A any one of claims 1 to 3
The exhaust gas purifying apparatus for a diesel engine, wherein the temperature raising control unit includes an exhaust gas temperature sensor for detecting a temperature of the exhaust gas.