JPH0315618A - Exhaust particulate processing device for internal combustion engine - Google Patents

Abstract

PURPOSE:To effectively carry out regenerative processing of a trap by heating the trap through raising of an engine revolution speed with throttling either one of intake or exhaust at idling driving during stop and then by operating a heating device with having most of exhaust bypassed. CONSTITUTION:A trap C for scavenging exhaust particulate, a device F for heating the trap C and a plurality of throttle valves G1 and G2 for throttling at least one of intake flow or exhaust flow are provided in an exhaust passage B of an internal combustion engine A. And at idling driving during a stop, a switch valve E is closed and the throttle valves G1 and G2 are throttled driven by a means H while engine revolution speed is raised by a predetermined amount by a means I. And after a predetermined time has passed, the switch valve E is opened, the heating device F is heated, and exhaust particulate is processed by a means J. After that, the switch valve E is closed, and the above heating and throttling actions are both stopped by a means K.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an exhaust particulate treatment device for an internal combustion engine.

<Prior Art> A conventional example of an exhaust particulate treatment device for an internal combustion engine is shown in FIGS. 4 and 5 (see S.A.E., Paper 850015).

That is, a turbine rotor of an exhaust turbo supercharger 2 is interposed in the exhaust passage 1 of the engine, and a trap 3 with a catalyst for collecting exhaust particulates in the exhaust is interposed in the exhaust passage 2 upstream of the turbine rotor. ing.

As shown in FIG. 5, in the catalyst trap 3, flow paths 3B substantially parallel to the exhaust flow are formed by a honeycomb-shaped lattice 3A made of a porous member such as ceramic, and an outlet and an inlet of each flow path 3B are formed. and are alternately sealed with sealing material 3C. Further, the catalyst-equipped trap 3 is coated with a catalyst.

The exhaust particles collected in the catalyst trap 3 are
Due to the catalytic action, the exhaust gas is re-combusted at an exhaust temperature of 350''C to 400''C or higher, and the catalytic trap 3 is regenerated.

In addition, in order to quickly regenerate the catalyst trap 3, the temperature of the exhaust gas introduced into the catalyst trap 3 is lowered from that during normal operation by making the exhaust gas bypass the turbine of the exhaust turbo supercharging m2 and by optimizing the gear ratio of the transmission. is also increasing.

Problems to be Solved by the Invention However, in such conventional exhaust particulate treatment devices, the exhaust gas temperature is controlled by bypassing the turbine of the exhaust turbo supercharger or by optimizing the gear shift value of the transformer during driving. Since the trap is regenerated by increasing the temperature, the exhaust temperature cannot be raised sufficiently without impairing driving performance when driving in a driving range where the exhaust gas temperature is low, such as in an urban area. As a result, the trap is not regenerated sufficiently and becomes clogged, leading to an increase in exhaust pressure and deterioration of output and fuel efficiency.Additionally, if a large amount of accumulated exhaust particulates burns at once, the trap will melt. There was a problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an exhaust particulate treatment device for an internal combustion engine that can periodically regenerate the trap and prevent the trap from clogging.

<Means for Solving the Problems> For this reason, the present invention, as shown in FIG. exhaust bypass passage D;
An on-off valve E that opens and closes the exhaust bypass passage D, a heating device F that heats the trap, and a throttle valve G that throttles at least one of the intake air flow and the exhaust flow downstream of the catalyst trap.
G. , the on-off valve E is closed and the throttle valve G. , G2, and a rotation speed increasing means I that increases the engine rotation speed by a predetermined amount while the valve drive means H is in operation; Exhaust particulate processing means J that opens the valve E and heats the heating device F; and after the operation of the exhaust particulate processing stage J, closes the opening/closing valve E and the heating device F.
heating operation and said throttle valve G. , and stop means K for stopping the throttle operation of G2.

<Function> In this way, while the vehicle is stopped and the exhaust bypass passage is closed, at least one of the intake throttling and exhaust throttling is performed while the engine rotational speed is increased to raise the exhaust temperature and heat the playing cards. With the exhaust bypass passage open and exhaust gas flowing through the exhaust bypass passage, the heating device is operated to regenerate the trap, thereby preventing deterioration of fuel efficiency and output by periodically performing regeneration processing. This makes it possible to prevent the trap from melting away.

<Example> Embodiments of the present invention will be described below based on the drawings.

2 and 3 show a first embodiment of the invention.

In FIG. 2, a trap 13 with a catalyst is interposed in an exhaust passage l2 of a diesel engine l1, and a trap 13 with a catalyst is installed in the exhaust passage l2.
The upstream exhaust passage 12 is provided with an electric heater 14 as a heating device for heating exhaust gas. An exhaust bypass passage 15 is provided to bypass the catalyst trap 13, and a butterfly-type on-off valve 16 is provided in the exhaust bypass passage l5.
is interposed. The external terminal of the electric heater 14 is connected to an external power source outside the vehicle since a large capacity is required to raise the exhaust gas to a high temperature.

Further, an intake throttle valve 18 as a throttle valve is interposed in the intake passage l7 of the diesel engine 11. The electric heater 14 is energized by a signal from a control device 19, and the on-off valve l6 and the intake throttle valve 18 are driven to open and close by a control signal from the control device 19. Here, during normal driving, the on-off valve 16 is kept closed, the intake throttle valve 18 is kept open, and the power supply to the electric heater 14 is stopped.

Next, the operation will be explained according to the operating procedure shown in the flowchart of FIG.

While the vehicle is running, all of the exhaust particles in the exhaust gas are collected in the catalyst trap 13 because the bypass passage 15 is closed, and the exhaust gas is purified. And trap with catalyst 1
The exhaust particulates collected in the trap 13 are re-burned by the exhaust gas temperature only without using the electric heater 14 in the operating range where the exhaust temperature is 350''C to 400'C or higher due to the catalytic action, and the catalyst trap 13 is re-burned. will be played.

However, when driving at low to medium speeds such as when driving in a city, the exhaust temperature is mostly below 300°C, so the exhaust gas temperature alone is not enough to regenerate the catalyst trap 13, and the exhaust particles enter the catalyst trap 13. Deposited. At this time, it is possible to heat the exhaust gas with the electric heater 14 while driving to re-burn the exhaust particulates, but most of the heat is taken away by the exhaust gas, so the electric capacity is extremely large in order to effectively re-burn the exhaust gas. (for example, several tens of kilowatts or more) is unrealistic. Further, it is not preferable to open the bypass passage 15 while the vehicle is running from the viewpoint of exhaust gas purification.

Therefore, in this embodiment, maintenance work is performed on commercial vehicles such as buses and trucks, where maintenance work is relatively easy, while the vehicle is stopped, such as when the driver returns to the garage.

That is, first, at Sl, the driver turns off the accelerator to bring the vehicle into an idling state, and then connects an external power source to the external terminal of the electric heater 14. As this external power source, an on-board battery may be used, and preferably one with a larger capacity than the on-board battery is used.

In S2, when the regeneration start switch (not shown) is turned on, the control device l9 continues to fully close the on-off valve l6 and drives the intake throttle valve 18 to close to the set opening degree to perform intake throttling. . Instead of the intake throttle valve l8, an exhaust throttle valve may be provided in the exhaust passage 12 downstream of the catalyst trap 13 to throttle the exhaust gas, or the intake throttle and exhaust throttle may be used together.

The use of these may be determined by the exhaust temperature level, which is increased by the accelerator operation, and the set rotational speed, which will be described later.

Therefore, this portion constitutes the valve driving means.

In S3, an alarm lamp (not shown) is turned on to notify the driver that the next step is to proceed.

In S4, the driver depresses the accelerator to increase the engine rotation speed to a preset rotation speed, thereby increasing the exhaust temperature. Therefore, this portion constitutes a rotational speed increasing means.

In S5, it is determined whether or not a predetermined period of time (for example, 3 to 5 minutes) has elapsed since the control to increase the engine rotational speed has elapsed. If YES, the process advances to S6, and if NO, the process returns to S3. When the speed is controlled to increase for a predetermined period of time in this way, the exhaust gas temperature quickly rises to the catalyst activation temperature of the catalyst trap 13 because the intake air is throttled.

In S6, an alarm lamp is turned on to notify the driver that the rotation speed increase control has ended and that the next stage will proceed.

In S7, the accelerator is released to stop the rotational speed increase control, and the process proceeds to S8.

In S8, the on-off valve 16 is opened to open the exhaust high-pass passage 1.
5 is opened, and energization to the electric heater 14 is started. As a result, most of the exhaust gas discharged at this time during idling flows through the exhaust high-pass passage l5.
Even if the exhaust temperature is low (the exhaust temperature during idling is 10
(around 0°C) can prevent the catalyst trap 13 from being cooled by exhaust gas, and can maintain the active state of the catalyst in the catalyst trap 13. Furthermore, since the exhaust gas introduced into the catalyst trap 13 is heated by the electric heater 14 and the oxygen concentration in the exhaust gas during idling is high, re-combustion of exhaust particulates is maintained well and the effect of the electric heater 14 is fully brought out. At the same time, the catalyst trap 13 can be regenerated.

In S9, the control in S8 determines whether a set time (for example, 10 to 20 minutes) has elapsed, and if YES, it is determined that the playback process has ended, and the process proceeds to SIO, and if NO, the process proceeds to S8.
Return to

Therefore, S8 and S9 constitute exhaust particulate processing means.

In SIO, the on-off valve l6 is closed to close the exhaust bypass passage 15, the intake throttle valve l8 is fully opened to stop the intake throttle, and the electric heater 14 is de-energized to stop the regeneration process.

Therefore, this portion constitutes the stopping means.

At Sll, an alarm lamp is turned on to notify the driver that the regeneration process has been completed.

After this, the driver may restart the vehicle or may stop the engine.

As explained above, when the engine is idling while stopped, the exhaust bypass passage 15 is closed, the intake air is throttled, and the engine rotational speed is increased to raise the exhaust temperature to the catalyst activation temperature and activate the catalyst. After that, the engine speed is lowered to idle speed, the exhaust bypass 15 is opened, and the electric heater 14 is energized to re-burn the exhaust particulates, so that the catalytic trap 13 can be regenerated efficiently and the driver can regenerate it. Processing can be performed periodically. Therefore, the regeneration process of the catalyst trap 13 can be carried out frequently and reliably, which prevents the catalyst trap 13 from clogging, suppresses the deterioration of fuel efficiency and output, and prevents a large amount of exhaust particulates from being re-burned. Trap with catalyst 13
can prevent melting and damage.

4 and 5 show a second embodiment of the invention.

Note that explanations of the same elements as in the first embodiment will be omitted, and only different parts will be explained.

In FIG. 4, a valve shaft 21 of an on-off valve 16 that opens and closes the exhaust bypass passage 15 and an output shaft of a drive motor 22 are connected by a wire 23, and the drive motor 22 is operated by a drive signal from a control device 24. The on-off valve 1 is controlled
6 to open and close.

Note that 25 is a coil spring.

Next, the operation will be explained according to the flowchart shown in FIG.

In this embodiment, the manual operation in the first embodiment is automated, and when the regeneration start switch is turned on while the vehicle is stopped, the routine shown in the flowchart of FIG. 5 is executed.

That is, in S21, it is determined whether or not the engine is idling,
When the answer is YES, the process advances to S22, and when the answer is No, the routine is ended.

In S22, the on-off valve 16 is kept fully closed to close the exhaust bypass passage 15, and the intake throttle valve (not shown) is driven to close to a set opening degree to throttle the intake air. At this time, the exhaust throttle valve may also be operated.

In S23, the opening degree of the control lever (not shown) of the combustion injection pump (not shown) is controlled in the opening direction by a predetermined opening degree. This increases the engine rotation speed.

In 324, it is determined whether the actual rotation speed has reached the set rotation speed, and if YES, the process advances to S25, and if No, the process returns to 323, and the opening degree of the control lever is further controlled in the fully open direction by a predetermined opening degree. .

In S25, the opening degree of the control lever is maintained at a constant position to maintain the engine rotational speed at the set rotational speed.

In S26, it is determined whether or not a predetermined period of time has elapsed during which the engine rotational speed was maintained at the set rotational speed. If YES, the process proceeds to 327, and if NO, the process proceeds to 325.

As a result, the exhaust gas temperature is sufficiently raised to the catalyst activation temperature of the catalyst-equipped trap 13 in combination with the intake throttle.

In S27, the control lever is returned to the idle position.

At 328, the on-off valve l6 is opened to open the exhaust bypass passage l5 and to start energizing the electric heater (not shown). As a result, most of the exhaust gas passes through the exhaust bypass passage 15, so that the trap 13 with a catalyst can be effectively regenerated by the electric heater while preventing the trap 13 with a catalyst from being cooled.

In step 329, the intake throttle valve is fully opened to stop the intake throttle, and then the process proceeds to S30.

At 330, the control at 328 determines whether or not a set time has elapsed, and when YES, it is determined that the regeneration process has ended and the process proceeds to 331, and when NO, the process returns to S28.

In S31, the on-off valve 16 is closed to close the exhaust bypass passage 15, and the electric heater is de-energized to stop the regeneration process.

In S32, an alarm lamp is turned on to indicate to the driver that the regeneration has ended. An alarm may be provided by a buzzer or the like.

When supplying the operating voltage to the electric heater from the alternator, the engine rotation speed is maintained at a predetermined amount below the idle rotation speed without returning the control lever to the idle position in S27 to supply sufficient electric power. It may also be supplied by a heater.

This configuration also provides the same effects as the first embodiment.

<Effects of the Invention> As explained above, the present invention increases the exhaust temperature by increasing the engine rotation speed while closing the exhaust bypass passage and performing at least one of intake throttling and exhaust throttling during idle operation while stopped. After heating the playing cards, the exhaust bypass passage is opened and the heating device is operated while most of the exhaust gas flows through the exhaust high-pass passage, so that trap regeneration processing can be performed efficiently and periodically. As a result, it is possible to suppress deterioration of fuel efficiency and output, and prevent melting and damage of the trap.

[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 present invention, Fig. 3 is a flowchart of the same as above, and Fig. 4 is a configuration showing a second embodiment of the present invention. 5 is a flowchart of the same as above, FIG. 6 is a block diagram showing a conventional example of an exhaust particulate treatment device, and FIG. 7 is an enlarged view of the main part of the same. 11...Diesel engine l2...Exhaust passage
13... Trap with catalyst l4... Electric heater
15... Electric heater 16... Open/close valve

Claims (1)

[Claims] A trap installed in an exhaust passage of an engine to collect exhaust particulates, an exhaust bypass passage that bypasses the trap, an on-off valve that opens and closes the exhaust bypass passage, a heating device that heats the trap, and an intake flow. a throttle valve that throttles at least one of the exhaust flow downstream of the catalyst trap and the exhaust flow downstream of the catalyst trap; a valve drive means that drives the on-off valve to close and throttles the throttle valve during idling operation during a stopped state; a rotational speed increasing means for increasing the engine rotational speed by a predetermined amount during operation; and an exhaust particulate processing means for opening the on-off valve and heating the heating device when the engine rotational speed has been increased for a predetermined period of time. and a stop means for closing the on-off valve and stopping the heating operation of the heating device and the throttling operation of the throttle valve after the exhaust particulate processing means is activated. Exhaust particulate treatment equipment.