JPH0217137Y2 - - Google Patents

Description

[Detailed description of the invention] [Technical field of the invention] The invention relates to a particulate purification device for an internal combustion engine,
In particular, particulate purification for internal combustion engines that allows the re-combustion of collected exhaust particulates to be automatically and efficiently carried out by a control device, and to minimize the decline in output and fuel efficiency of the internal combustion engine during re-combustion. Regarding equipment.

[Technical background of the invention and its problems] Exhaust gas emitted from internal combustion engines in general, and diesel engines in particular, contains unburned carbon particles with unburned hydrocarbons, sulfur oxides, or nitrogen oxides attached. It is known that it includes.
When these particulates are emitted into the atmosphere as so-called smoke, they pollute the air and cause harm to the human body.For this reason, in recent years vehicles have been equipped with internal combustion engines to eliminate this exhaust pollution. The exhaust system is equipped with an exhaust gas purification device.

This type of purification device is equipped with a filter that deposits and collects particulates in the exhaust gas in the middle of the exhaust pipe, and is further provided with a heating means upstream of this filter. There is an apparatus which periodically incinerates the exhaust particulates collected by the filter. The heating means increases the temperature of the exhaust gas itself to be discharged by reducing the intake air amount of the internal combustion engine and bringing the air-fuel ratio closer to the stoichiometric air-fuel ratio, and collects the exhaust gas with this high temperature exhaust gas. There is a method of incinerating exhaust particulates, which has conventionally been done by throttling a throttle valve provided in the intake pipe. However, if the amount of intake air in all cylinders of an internal combustion engine is reduced at the same time, the engine output will be significantly reduced, resulting in a problem that the drivability of the vehicle will be significantly deteriorated.

Therefore, in order to solve such problems,
Up to now, a carbon particulate purification device for an internal combustion engine described in Japanese Patent Application Laid-Open No. 57-124019 has been proposed. The carbon particulate purification device described in this proposal divides the internal combustion engine from the middle of the intake system to the middle of the exhaust system into multiple systems, and each of these systems is operated independently, mainly by throttling the intake air. It consists of a purification device consisting of a valve and a filter for collecting exhaust particulates, and these are operated alternately as appropriate for each system to re-burn the exhaust particulates, thereby suppressing a decrease in the output of the internal combustion engine. It was hot.

However, in this proposal, the intake throttle amount is assumed to be constant, and changes in exhaust gas temperature due to changes in the load applied to the internal combustion engine are not taken into account.
There is a risk of over-throttling the intake air under high loads, or under-throttling the intake air under low loads.
This was not completely satisfactory in terms of suppressing a decrease in engine output and deterioration of fuel efficiency, and in terms of efficiently performing re-combustion.

[Purpose of the invention] The present invention has been devised in view of the above-mentioned problems and to effectively improve them.

The purpose of this invention is to control the re-combustion of collected exhaust particulates according to operating conditions such as the load applied to the internal combustion engine, and to suppress as much as possible the reduction in engine output and deterioration of fuel efficiency during re-combustion. An object of the present invention is to provide a particulate purification device for an internal combustion engine that can perform the following steps.

[Summary of the invention] This invention installs a sensor that detects the exhaust temperature in the exhaust system downstream of the filter that collects exhaust particulates, and detects the engine load and rotation speed when the exhaust pressure in the exhaust system exceeds a predetermined value. A particulate purification device for an internal combustion engine includes a control device that adjusts the opening degree of a throttle valve in an intake system according to a detected value of a sensor and opens the throttle valve when the time integral value of exhaust temperature reaches a predetermined value. This is what I did.

[Embodiment of the invention] A preferred embodiment of the invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows a schematic configuration of a particulate purification device 1 for an internal combustion engine according to the present invention. As shown,
The intake system 3 and exhaust system 4 of the multi-cylinder internal combustion engine 2 are each divided into a plurality of systems A, B, . . . . Each of these systems A, B... is a collection of cylinders of the internal combustion engine 1 whose intake/exhaust timings are the same in order to prevent intake interference and exhaust interference. ,4b
and are formed in correspondence with each other. The illustrated example shows an in-line four-cylinder internal combustion engine 1, in which intake and exhaust systems A for cylinder groups #1 to #4 (hereinafter referred to as the first intake and exhaust system) and cylinder groups #2 to #3 are used. The cylinder group intake and exhaust system (hereinafter referred to as the second intake and exhaust system) B is divided into two parts.

The first intake/exhaust system A and the second intake/exhaust system B include the intake systems 3a and 3b, respectively.
Intake air throttle valves 5a and 5b are provided to adjust the amount of air sucked into these. These throttle valves 5a, 5b are provided upstream of the intake pipes 6a, 6b forming the intake systems 3a, 3b, and
6b is branched downstream from this to form intake manifold portions 7a, 7a, 7b, and 7b for each cylinder.

Further, on the respective exhaust systems 4a, 4b side, exhaust particulates are collected downstream of the collecting parts 10a, 10b of the exhaust manifolds 9a, 9a, 9b, 9b of each cylinder of the exhaust pipes 8a, 8b forming the exhaust system. Filters 11a and 11b with catalysts are provided to collect the water. These filters 11a, 11b
As shown in FIGS. 2 and 3, a stainless steel caning 12 that forms part of the exhaust pipe and is formed in an oval shape with an expanded diameter or width in the cross-sectional direction of the pipe, Air permeable ceramic filter members 13, 13 are elastically supported by a wire mesh 14, and the filter members 13, 13 are formed by being elastically supported by a wire mesh 14.
The space between the canning 12 and the canning 12 is shielded by gas sealing materials 15, 15 such as interrams. And, in the filter members 13, 13,
In order to promote re-combustion of exhaust particulates such as carbon collected by this, a metal-based oxidation catalyst or a dedicated catalyst of Deidel particulate (exhaust particulates) is supported.

Further, as shown in FIG. 1, the filter 11
In the exhaust system upstream from a, 11b, the pressure in the exhaust pipes 8a, 8b is increased by the filters 11a, 11b, which are disposed in the exhaust pipes 8a, 8b and are clogged by adhering to and collecting exhaust particulates. Exhaust pressure sensors 16, 16b are provided to detect exhaust pressure. The exhaust pressure sensors 16a and 16b are connected to a control device 18 that automatically throttles the amount of intake air taken into the intake system by controlling the operation of the intake system throttle valves 5a and 5b described above.
connected to. This control device 18 controls the exhaust pressure in one of the exhaust pipes 8a, 8b to exceed a set value in response to a signal from the exhaust pressure sensors 16a, 16b, and the filter 11a, 11b of that exhaust pipe collects and deposits the exhaust gas. When it is detected that the amount of exhaust particulates exceeds the allowable value, it is determined that the time has come to re-burn the exhaust particulates collected by the filters 11a and 11b, and the corresponding intake system 3a and 3b is The exhaust gas temperature is increased by reducing the intake air amount, and the exhaust gas heat is used to combust the exhaust particulates by issuing an operation command for the intake air throttle valves 5a and 5b.

On the other hand, the internal combustion engine 1 is provided with a load detection sensor 21 consisting of a potentiometer 19 and a tachometer 20 in order to detect the load applied thereto and its rotational speed. This load detection sensor 21 is connected to a correction control device 22 section. The above-mentioned control device 18 is connected to this correction control device 22, and the throttle valve 5a,
When the operation command 5b is input, the load applied to the internal combustion engine 1 is controlled by the signal from the load detection device 21 to control the throttle valves 5a and 5b according to the operating conditions.
The throttle valves 5a and 5b are driven and controlled so that the opening degree is corrected and the opening degree is increased when the exhaust temperature is high under high load, and the opening degree is decreased during low load when the exhaust temperature is low.

On the other hand, the exhaust systems 4a, 4b downstream of the filters 11a, 11b include the filters 11a, 11b.
Temperature sensors 23a and 23b are provided to detect whether the exhaust particulates deposited on the exhaust gas 11b are being burned or distorted. In the illustrated example, filters 11a, 11
It is provided on the downstream side of the canning 12 forming the canning 12, is connected to the device 18, and is configured to determine the end timing of reburning. That is, the device 18 is
Immediately after issuing the operation command for the throttle valves 5a and 5b,
The signals inputted from the temperature sensors 23a and 23b are integrated over time, and when the integrated value S reaches the set value as shown in FIG.
It is configured to consider that the exhaust particulates collected by the exhaust gas 11b have been incinerated, and to determine that the end time of re-combustion has been reached, thereby canceling the operation command for the intake air throttle valves 5a and 5b.

In addition, in Fig. 1, 24 is an air cleaner, and 2
5 is an exhaust muffler provided downstream where the first intake/exhaust system A and the second intake/exhaust system B are assembled.

Next, the operation of the present invention will be explained.

Exhaust gas discharged from the internal combustion engine 1 is guided to exhaust particulate collection filters 11a and 11b provided in exhaust systems 4a and 4b, where exhaust particulates such as unburned carbon contained in the exhaust gas are captured. It is collected, purified, and released into the atmosphere.

The amount of exhaust particles collected and deposited on the filters 11a and 11b increases in accordance with the distance traveled by the vehicle, increasing the ventilation resistance of the filters 11a and 11b.
And the exhaust pipe 8 on the upstream side of the filters 11a and 11b
The exhaust pressure inside a and 8b is increased. Exhaust pressure sensor 1
6, 16b senses the pressure and transmits it to the control device 18. The controller 18 controls the pressure to
As shown in the figure, when the set value _P1 is reached, it is determined that the time has come to re-burn the exhaust particulates collected and deposited on the filters 11a and 11b, and the throttle valves 5a and 5
Issue the activation command b. Upon receiving this operation command, the correction control device 22 detects the load, etc. applied to the internal combustion engine 1 at that time, and responds to the input signal from the load detection sensor 21 which notifies the engine operating status. The aperture degree (opening degree) of 5b is corrected and determined, and it is driven to start the reburning operation of exhaust particulates.

When the throttle valves 5a and 5b are throttled, the amount of intake air is reduced, the air-fuel ratio approaches the stoichiometric air-fuel ratio, the exhaust gas temperature is increased, and the filter 11
Promote the exothermic action of the catalyst supported on a and 11b
Increases generation of HC and CO components. This raises the temperature of the catalyst to its activation temperature, promoting re-combustion of collected and deposited exhaust particulates.

Further, the control device 18 issues an operation command for the throttle valves 5a, 5b, and at the same time, the temperature sensors 23a,
The signal input from 23b is integrated over time. As shown in FIG. 4, when this integral value S reaches the set value, it is determined that the collected exhaust particulates have been incinerated and the end time of re-combustion has been reached, and the throttle valve 5a,
5b. When this operation command is released, the correction control device 22 causes the throttle valve 5 to
a and 5b are returned to the fully open state, and the internal combustion engine 1 is returned to normal operation. Further, the above-mentioned control is performed independently and alternately in the first intake/exhaust system A and the second intake/exhaust system B. FIG. 6 shows a flowchart of the control described above. As shown in the figure, the reburning of particulates in the internal combustion engine is programmed so that the first intake and exhaust system A is first reburned, and then the second intake and exhaust system B is reburned. Therefore, since the intake air is not restricted to all cylinders during reburning, it is possible to reduce the decrease in the output and fuel efficiency of the internal combustion engine 1 during reburning. Further, the amount of intake air throttled is controlled to the minimum necessary level according to the load applied to the engine 2. In other words, the degree of throttling is reduced at high loads, where the exhaust gas temperature is high, and increased at low loads, where the exhaust gas temperatures are low, so that the exhaust gas temperature is always kept constant near the lower limit temperature required for re-combustion. ing. Therefore, there is no risk of over-throttling or under-throttling the intake air, and since a filter with a catalyst is used, the amount of intake air throttling can be made relatively small, allowing efficient re-burning of exhaust particulates in a short time. Can be removed. Therefore, reductions in engine output, fuel efficiency, etc. during reburning can be further suppressed as much as possible, and the drivability of the vehicle during reburning can be further improved.

As shown in the flowchart of FIG. 7, the flow of the control method is such that when the reburning timing judgment for the first intake/exhaust system A is NO, the reburning timing for the second intake/exhaust system B is judged. , when this becomes NO, the re-combustion timing of the first intake/exhaust system A may be determined again.

[Effects of the invention] In summary, the present invention provides the following excellent effects.

(1) The intake throttle amount is appropriately controlled according to the operating conditions such as the load on the internal combustion engine, so there is no risk of over- or under-throttling the intake air, and exhaust particulates are efficiently burned and removed in a short time. can.

(2) Since the amount of intake air throttling is controlled to the minimum necessary amount, it is possible to suppress as much as possible a decrease in the output and fuel efficiency of the internal combustion engine during reburning.

(3) The drivability of the vehicle during reburning can be further improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing a preferred embodiment of the present invention, FIG. 2 is a cross-sectional plan view of a filter equipped with a catalyst, and FIG.
The figure is a perspective view showing the filter member, Figure 4 is a diagram showing an example of the exhaust gas temperature curve from the start to the end of reburning, Figure 5 is a diagram showing the relationship between mileage and exhaust pressure, and Figure 6 is a diagram showing the relationship between travel distance and exhaust pressure. 7 is a flowchart showing one example of the control method, and FIG. 7 is a flowchart showing another example of the control method. In the figure, 1 is a particulate purification device for an internal combustion engine, 2 is a multi-cylinder internal combustion engine, 3, 3a, 3b are intake systems, 4, 4
a, 4b are exhaust systems, 5a, 5b are throttle valves, 11
a, 11b are filters with catalysts, 16a, 16b
18 is a control device, 22 is a correction control device, and 23a and 23b are temperature sensors.

Claims (1)

[Scope of utility model registration request] A sensor that detects the exhaust temperature is installed in the exhaust system downstream of the filter that collects exhaust particulates, and when the exhaust pressure in the exhaust system exceeds a predetermined value, the intake air is A particulate purification device for an internal combustion engine, which is equipped with a control device that adjusts the opening degree of a throttle valve in the system and opens the throttle valve when the time integral value of exhaust gas temperature reaches a predetermined value.