JPH0216319A - Exhaust purification device for internal combustion engine - Google Patents

Abstract

PURPOSE:To heighten the collection efficiency of exhaust corpuscles, by providing an exhaust bypass passage so as to bypass a trap within an exhaust passage, and making control possible so that exhaust may be circulated to the side of the trap at part of an exhaust return operation sphere and at the time of a speed reduction operation from a predetermined revolution sphere. CONSTITUTION:An exhaust bypass passage D is provided so as to bypass a trap C which is interveniently provided at an engine exhaust passage B and compensates corpuscles in exhaust. The selective introduction of exhaust into this exhaust bypass D and the trap C is made possible in accordance with the operation of an opening/ closing valve E. Also, an engine operation state detecting means F is provided, and its output is inputted into a valve drive control means G. And the opening/closing valve E is controlled in drive by means of this valve drive control means G so that exhaust may flow to the trap C at least part of an exhaust return operation sphere and at the time of a speed reduction operation from a predetermined revolution sphere. Also, the operation of an exhaust return device A is stopped by means of an exhaust return stopping means H at the time of the speed reduction operation from this predetermined revolution sphere.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an exhaust gas purification device.

<Prior art> As a conventional example of an exhaust gas purification device, there is one as shown in FIG.
-Refer to Publication No. 30816).

That is, an intake throttle valve 3 is interposed in the intake passage 2 of the diesel engine 1, and an intake manifold 4 downstream of the intake throttle valve 3 and an exhaust manifold 5 are connected to each other by an exhaust gas recirculation passage (referred to as an EGR passage) 6. There is. Further, the EGR passage 6 includes an exhaust recirculation control valve (hereinafter referred to as an EGR valve).
7 is interposed.

The flow area of the EGR passage 6 is controlled by controlling the opening of the EGR valve 7, and during engine medium load operation, the exhaust gas is recirculated to the combustion chamber via the intake manifold 3 due to the pressure difference between the exhaust gas and the intake air. ing. Further, in a low rotation/low load operating region, the intake throttle valve 3 is driven to close to throttle the intake air, and the EGR pulp 7 is controlled to open, thereby increasing the pressure difference and recirculating the exhaust gas.

<Problems to be Solved by the Invention> However, in such conventional exhaust gas purification devices, exhaust gas recirculation is performed for the purpose of exhaust gas purification, but if exhaust gas recirculation is performed in the low speed/low load operating region, the exhaust gas There was a problem in that a large amount of fine particles, particularly soluble fractions (SOF), were discharged.

The present invention has been made in view of the above circumstances, and by performing exhaust gas recirculation in the low speed and low load operating region, even if a large amount of exhaust particulates are generated, it is possible to suppress the exhaust particulates from being emitted into the atmosphere. The purpose is to provide an exhaust purification device.

(Means for Solving the Problems) Therefore, as shown in FIG. a trap C that collects particulates in the exhaust gas, an exhaust bypass passage that bypasses the trap C, an on-off valve E that selectively introduces exhaust gas into the lid gas bypass passage and the trap C, and an engine. and an operating state detecting means F for detecting the operating state of the engine, and an operating state detecting means F that detects the operating state of the exhaust gas recirculating device A based on the detected operating state.・Valve drive control means G that drives and controls the opening/closing valve E to cause exhaust gas to flow through the wrap C, and the exhaust gas recirculation device A during deceleration operation from the predetermined rotation range.
The exhaust gas recirculation stop means H is provided to stop the operation of the exhaust gas recirculation.

In this way, during exhaust gas recirculation, the exhaust gas is caused to flow through the trap and exhaust particulates are collected by the trap, and during the deceleration operation, the exhaust gas is caused to flow through the trap and the exhaust particulates are processed.

<Example> Below, an example of the present invention will be described based on the drawings. In each embodiment, the same elements as in the conventional example are designated by the same reference numerals as in FIG. 9, and their explanation will be omitted.

2 and 3 show a first embodiment of the invention.

In FIG. 2, a catalyst-equipped trap 12 is interposed in an exhaust passage 11 downstream of a gathering part of an IJI-% manifold 5 of a diesel engine, and this catalyst-equipped trap 12 is housed in a trap case 14 via a buffer material 13. ing. A butterfly-type on-off valve 16 is interposed in the exhaust bypass passage 15 that bypasses the catalyst trap 12, and one end of a lever 17 is attached to the valve shaft of the on-off valve 16.

A tip end of a rod 18a of a diaphragm device 18 is rotatably attached to the other end of the lever 17, and a pressure chamber 18b of the diaphragm device 18 is connected to an output port of a three-way solenoid valve 19.

When energized, the three-way solenoid valve 19 introduces negative pressure air from a vacuum pump (not shown) into the pressure chamber 18b to close the on-off valve 16, while when de-energized, the three-way solenoid valve 19 closes the pressure chamber 18b.
Atmospheric air is introduced into the tank, and the on-off valve 16 is driven to open.

Furthermore, a detection signal from an engine rotation sensor 21 and a detection signal from a lever opening sensor 24 that detects the opening of the control lever 23 of the injection pump 22 are input to the control device 20 which is composed of a microcomputer or the like. ing.

The control device 20 operates according to a program based on the flowchart in FIG. 3, and outputs operating signals to the three-way solenoid valve 19, the intake throttle valve stealing device 25, and the exhaust recirculation control device 26. .

Here, the engine rotation sensor 21 and the lever opening sensor 24 constitute an operating state detection means, and the diaphragm device 18, the three-way solenoid valve 19, and the control device 20 constitute a valve drive control means. Further, the control device 20 and the exhaust gas recirculation control device 26 constitute an exhaust gas recirculation stopping means. Furthermore, E.G.R.
The passage 6 and the EGR valve 7 constitute an exhaust gas recirculation device.

Next, the operation will be explained according to the flowchart of FIG. 3 and with reference to FIG. 4.

At Sl, various detection signals of the detected engine speed and load (2) are read.

In S2, based on the detected engine speed and load, the current operating state is displayed on the map in the white smoke generation area (
If the answer is YES, the process proceeds to S3, and if the answer is NO, the process proceeds to S8.

In S3, it is determined whether the current operating state is idling based on the detected engine speed and load ■1. If YES, the process advances to S4, and if NO, the process advances to S5.
Proceed to.

In S5, it is determined whether the current operating state is under engine braking (smash region in Fig. 4) (during deceleration operation) based on the detected engine speed and load. The process proceeds to S6, and when the answer is No, the process proceeds to S8 without passing through S6.

In S6, based on the detected engine rotation speed, a predetermined rotation range (1500 r, p, m
, ~4000r, p, m, ) is determined, and if the result is ¥ES, the process proceeds to S7, and if NO, the process proceeds to S8.

In S7, it is determined whether or not the EGR region (shaded region in FIG. 4) is reached, and when YES, that is, when the engine brake is activated from a predetermined rotation range in the EGR2H region, the process proceeds to S9, and when NO, the process proceeds to S4.

In S9, an EGR cut signal is output to the exhaust gas recirculation device 26, the EGR passage 6 is closed by the EGR valve 7, and exhaust gas recirculation is stopped, and then the process proceeds to S4.

In S4, the three-way solenoid valve 19 is energized to introduce atmospheric air into the pressure chamber 18b of the diaphragm device 18 via the three-way solenoid valve 19. As a result, the on-off valve 16 is closed as shown by the solid line in FIG. 2, and the entire amount of exhaust gas passes through the catalyst trap 12 and is discharged into the atmosphere.

On the other hand, in S8, the three-way solenoid valve 19 is de-energized, and negative pressure air is introduced into the pressure chamber 18b of the diaphragm device 18 via the three-way solenoid valve 19. This causes the on-off valve 16 to switch to the second
The valve is opened as shown by the broken line in the figure, and all or most of the exhaust gas is discharged into the atmosphere through the exhaust bypass passage 15 without passing through the catalyst trap 12.

Here, during normal operation, the EGR valve 7 is opened in the Snake GR region shown in FIG.
After being introduced into the combustion chamber, exhaust gas is recirculated.
Outside the EGR region, the EGR valve 7 is closed and exhaust gas recirculation is stopped.

In this way, as shown in Fig. 4, the on-off valve 1 is
6 is closed, and the exhaust gas begins to pass through the trap 12 with catalyst. In addition, even in operating states other than the above-mentioned operating states, as shown in FIG. 4, when the engine brake is applied from a predetermined rotation range, the on-off valve 16 is closed to allow the exhaust gas to pass through the catalyst trap 12. The collected exhaust particulates are regenerated.

At this time, even if the operating state enters the EGR region, exhaust gas recirculation is stopped. Further, in an operating range other than the above, the on-off valve 16 is opened regardless of whether or not the engine brake is activated, and the exhaust gas is discharged into the atmosphere without passing through the catalyst trap 12.

Therefore, even if a large amount of exhaust particulates, especially soluble organic components, are generated due to exhaust gas recirculation in the low-speed/low-load operating range, they will be collected by the catalyst trap 12 and will not be released into the atmosphere. It is possible to suppress the

By the way, since there is a pressure loss in the exhaust gas in the catalyst trap 12, when the exhaust gas is passed through the catalyst trap 12 and the exhaust gas is recirculated, the pressure difference between the intake manifold 4 and the exhaust manifold 5 increases, and the exhaust gas recirculation rate increases. increase For this reason, the combustion state of the engine deteriorates and unburnt fuel (HC) and white smoke increase, so exhaust gas recirculation is stopped. Also, when the engine brake is activated, -
Since the fuel supply to the engine is stopped in a C-like manner, the amount of unburned fuel, No Exhaust particles such as soluble organic components collected in the catalyst trap 12 can be treated without increasing the amount of exhaust particles.

FIG. 5 is a flowchart showing a second embodiment of the present invention. In FIG. 5, steps that are the same as the number of steps in FIG. 3 are given the same number of steps as in FIG. 3, and the explanation thereof will be omitted.

That is, when it is determined in S3 that the operation is idling, the SIO outputs an actuation signal to the intake throttle control device 25 to drive the intake throttle valve 3 fully open, and then drives the on-off valve 16 to close in S4. let In this way, when the exhaust gas is passed through the catalyst trap 12, the exhaust pressure increases, so the intake manifold 4 and the exhaust manifold 5
Since the pressure difference increases, exhaust gas recirculation can be performed without closing the intake throttle valve 3, and an increase in the amount of unburned fuel discharged during idling operation can be suppressed.

FIG. 6 shows a third embodiment of the invention. Incidentally, the same elements as in the first embodiment are given the same reference numerals as in FIG. 2, and the explanation thereof will be omitted.

In FIG. 6, the exhaust side end of the EGR passage 31 is connected to the exhaust passage 11 downstream of the catalyst trap 12. Also, is the detection signal from the water temperature sensor 32 that detects the engine cooling water temperature controlled? ] n The device 33 is operated manually.

The control device 33 operates according to a program based on the flowchart of FIG. 7, and is designed to check various devices 1i', which will be described later.

Next, the operation will be explained in accordance with the flowchart of FIG. 7 and with reference to FIG. 8.

Sll reads various detection signals such as engine rotational speed.

In S12, the detected cooling water temperature T. It is determined whether or not the temperature is 60° C. or higher. If YES, it is determined that the warm-up has been completed and the process proceeds to S13; if NO, the process proceeds to 325.

In S13, based on the detected engine speed and load, the current operating state is determined to be engine brake activation (
It is determined whether or not it is in the smash area (in FIG. 8), and if YES, the process advances to S14, and if NO, the process advances to 318.

In S14, the EGR valve 7 is closed to stop exhaust gas recirculation, and then the process proceeds to S15.

In S15, the intake throttle valve 3 is fully opened to stop the intake throttle control, and then the process proceeds to S16.

In S16, based on the detected engine rotation speed,
It is determined whether or not engine braking is being applied from a predetermined rotation range that is a low speed to high speed driving range, and if YES, S22
If the answer is No, the process advances to S17.

In S17, the three-way solenoid valve 19 is de-energized, negative pressure air is introduced into the pressure chamber 18b of the diaphragm device 18 via the three-way solenoid valve 19, and the on-off valve 16 is opened. Thereby, the exhaust gas is discharged into the atmosphere without passing through the catalyst trap 12.

On the other hand, in S18, the current operating state is in the EGR region (eighth
(shaded area in the figure), and if YES, S1
If the answer is No, the process advances to S23.

In S19, the EGR pulp 7 is opened to start exhaust gas recirculation, and then the process proceeds to S20.

In S20, it is determined whether or not the intake throttle area (lattice-shaped area in FIG. 8) is present based on the detected engine rotational speed and load (2), and if YES, the process proceeds to S21.
When the result is O, the process proceeds to S22 without passing through S21.

In S21, the intake throttle valve 3 is driven to close by a predetermined amount to perform intake throttle control, and then the process proceeds to S22.

In S22, the three-way j:Lta valve 19 is energized, atmospheric air is introduced into the pressure chamber 18b of the diaphragm device 18 via the three-way solenoid valve 19, and the on-off valve 16 is closed. This results in
The exhaust gas is passed through a catalyst trap 12 and discharged into the atmosphere.

Further, in S23, the EGR valve 7 is closed to stop exhaust gas recirculation, and then the process proceeds to S24.

In S24, the intake throttle valve 3 is fully opened to the intake throttle side? ff1
After stopping l, the process proceeds to S17.

Further, when it is determined in Si2 that the cooling water temperature T is less than 60''C, the EGR valve 7 is closed to stop exhaust gas recirculation in 325, and then the process proceeds to S26.

In S26, the intake throttle valve 3 is fully opened to stop the intake throttle control, and then the process proceeds to S17.

In this way, when the operating state enters the EGR region after warm-up is completed, the on-off valve 16 is closed and the exhaust gas passes through the catalyst trap 12, allowing the catalyst trap 12 to collect exhaust particulates, especially soluble organic components. , thereby suppressing their emissions into the atmosphere. At this time, when the operating state enters the intake throttle range, the intake throttle valve 3 is driven to close and the exhaust gas recirculation rate is increased. In addition, even in operating states other than the above-mentioned operating states, when the engine brake is operated from a predetermined rotation range after warm-up is completed, the on-off valve 16 is closed and the exhaust gas passes through the catalyst trap 12. The exhaust particulates collected in the attached trap 12 are processed. At this time, exhaust gas recirculation is stopped.

Furthermore, in this embodiment, the exhaust gas downstream of the catalyst trap 12 is recirculated to the intake manifold 4, so that exhaust gas with greatly reduced exhaust particulates is introduced into the intake system.

Therefore, it is possible to suppress the deterioration of the lubricating oil of the engine, and also to suppress the wear of the inner wall of the combustion chamber and the sticking of the piston rings.

<Effects of the Invention> As explained above, the present invention allows exhaust gas to flow through the trap during exhaust gas recirculation operation, thereby preventing exhaust particulates such as soluble organic components generated during exhaust gas recirculation from being discharged into the atmosphere. In addition, the exhaust particulates can be efficiently processed during deceleration operation from a predetermined rotation range.

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to the claims of the present invention, Fig. 2 is a configuration diagram showing a first embodiment of the invention, Fig. 3 is a flowchart of the same, Fig. 4 is a diagram for explaining the operation of the above, 5 is a flowchart showing a second embodiment of the present invention, FIG. 6 is a configuration diagram showing a third embodiment of the present invention, FIG. 7 is a flowchart 1-1 of the same as above, and FIG. FIG. 9 is a configuration diagram showing a conventional example of an exhaust purification device for an internal combustion engine. 1...Diesel engine 6...EGR passage 7
... Snake GR valve 11 ... Exhaust passage 12.
...Catalyst trap 15...Exhaust bypass passage
16... Opening/closing valve 18... Diaphragm 20
．． 33...Control device 21...Engine rotation sensor
24... Lever opening sensor 25... Intake throttle control device 26... Exhaust recirculation control device Patent applicant Nissan Motor Co., Ltd. Representative Patent attorney Tomiji Sasashima t Figure 6 Figure 9

Claims (1)

[Claims] In an internal combustion engine equipped with an exhaust gas recirculation device that recirculates exhaust gas to an engine intake system, there is provided a trap that is interposed in an exhaust passage of the engine to collect particulates in the exhaust gas, an exhaust bypass passage that bypasses the trap, and an exhaust bypass passage that bypasses the trap. an on-off valve that selectively introduces exhaust gas into the passage and the trap; an operating state detection means that detects the operating state of the engine; and at least one of the exhaust recirculation operating ranges of the exhaust recirculation device based on the detected operating state. valve drive control means for driving and controlling the opening/closing valve to cause exhaust gas to flow through the trap during deceleration operation from the predetermined rotation region and the predetermined rotation region; and actuation of the exhaust gas recirculation device during deceleration operation from the predetermined rotation region. An exhaust gas purification device for an internal combustion engine, comprising: exhaust gas recirculation stopping means for stopping.