JPS6034717A - Fine particle collecting apparatus - Google Patents

Abstract

PURPOSE:To regenerate a trap at an optimum time by firing collected fine particles when the pressure loss, proportional to the amt. of the collected fine particles which are accumulated in a filter, exceeds a specified value. CONSTITUTION:The collected fine particles are fired when the specified amt. of the fine particles are accumulated in a filter 24 and the pressure loss thereof exceeds a specified value. Since the amt. of the collected fine particles corresponds almost precisely to the pressure loss in this way, the regeneration of a trap 20 can be carried out at an optimum time. Accordingly the damage and failure of the trap 20 can be prevented, and the highly reliable apparatus is obtained.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a particulate collection device that collects particulates contained in the exhaust gas of an engine, and particularly to a particulate collection device in which particulates collected in a filter are ignited and burned by a heater. This is a particulate collection bag that allows the filter to be reused.

[Background Art] Diesel engines may contain particulates in their exhaust gas. These fine particles are generated due to incomplete combustion of fuel and are made of carbon, hydrocarbons, metals, etc.
Flammable.

When the exhaust gas containing the fine particles is directly discharged from the vehicle, the exhaust gas becomes black smoke-like and is accompanied by an unpleasant odor.

Therefore, it is inconvenient to discharge such exhaust gas directly from the engine in terms of maintaining a clean and comfortable environment.

In this type of device, particulates contained in the exhaust gas are collected by a filter to purify the exhaust gas.

In addition, at a predetermined time before a predetermined amount of particulates are collected and accumulated in the filter and the output of the engine is reduced, the most upstream collected particulates are ignited by the heater. The ignited particulates act as a spark, and the collected particulates downstream self-combust due to the oxygen in the exhaust gas. This combustion completes the regeneration of the filter, making it possible to collect particulates again.

This kind of conventional? In conventional systems, the regeneration timing of the trap was determined based on the cumulative engine speed, vehicle mileage, or cumulative engine operating time, so the amount of particles collected differs depending on the driving conditions, etc., and the regeneration timing may vary. A large amount of particulates could accumulate on the surface.

Therefore, conventionally, when a large amount of fine particles that have been collected at this time are ignited, the temperature of the trap rises abnormally. As a result, there has been a problem that the trap is damaged or its durability is reduced.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its object is to provide a particulate collection device that does not cause damage to the trap or decrease in its durability.

[Summary of the Invention] In order to achieve the second object, the present invention provides a trap including a filter that collects particulates contained in engine exhaust gas and a heater that ignites the particulates collected by the filter; and a power supply circuit that supplies an ignition current to the heater when the pressure loss of the filter exceeds a predetermined value. It is characterized by

[Embodiments of the Invention] Hereinafter, embodiments of the apparatus according to the present invention will be described based on the drawings.

FIG. 1 shows the overall configuration of the apparatus of this embodiment.

In the figure, an intake throttle valve 12 is provided on the intake side of a diesel engine 10, and the intake throttle valve 12 is driven by an actuator 14.Furthermore, the intake throttle valve 12 is driven by an actuator 14, and further controls the fuel injection amount for the diesel engine 10. A valve 16 is provided, and an EGR valve 18 that recirculates exhaust gas to the intake side is provided between the intake and exhaust.

A trap 20 is provided in the exhaust route of the diesel engine 10. The casing 22 of the trap 20 is formed into a columnar shape with a substantially elliptical cross section with embossed ends. This casing 22 is filled with a filter 24 . The filter 24 can collect particulates contained in the exhaust gas of the diesel engine 10, and the particulates gradually accumulate from the exhaust inlet to the outlet of the filter 24.

Further, within the casing 22, a heater 26 is provided on the end surface of the filter 24 on the diesel engine 10 side for igniting the particulates collected on the filter 24.

Note that foamed ceramic is used for the filter 24 of this embodiment, and the filter 24 has a three-dimensional network structure skeleton having a large number of elliptical holes that communicate with each other.

Further, the heater 26 of this embodiment is connected to the electric power jji11.3 connected to the terminal 28-1.28-2 as shown in FIG.
0-1.30-2.3o-3,3o-4,30-5,3
It has 0-6, 3o-7, 3o-8. Note that the heater 26 is grounded to the body of the vehicle.

An ignition current is supplied to this heater 26 from a power supply circuit, and the power supply circuit is connected to a circuit 32 in FIG.
and an ECU 34. Chisel collar circuit 32
1 constitutes a main power supply circuit and consists of switching transistors 38 and 40 that chop the output current of the battery 36, and the chopping operation is controlled by an ECU 34 mainly composed of a microcomputer.

Furthermore, in FIG. 1, an exhaust passage 42 is formed bypassing the trap 20, and this exhaust passage 42 is provided with an exhaust flow rate control valve 44.

This exhaust flow rate control valve 44 is driven to open and close by a diaphragm 46, and the diaphragm 46 has a vSV of 48.5.
0. The vSV48 is connected to a vacuum pump (not shown), and the vsvso
is open to the atmosphere, and both are controlled by the ECU 34.

As mentioned above, the ECU 34 controls the diesel engine IO, heater 26. Although the exhaust flow rate control valve 44 is controlled,
Various detection signals are supplied to the ECU 34 to perform these controls.

In the mt diagram, the opening of the intake throttle valve 12 is determined by the opening sensor 5.
2, the intake side pressure of the diesel engine 10 is detected by the pressure sensor 54, and the engine water temperature is detected by the temperature sensor 5.
6 and the engine load are detected by a load sensor 58, respectively.

Also, the rotation speed of the diesel engine 10 is detected by the rotation speed sensor 6.
0, the vehicle speed is detected by the vehicle speed sensor 62, and the oxygen concentration in the exhaust gas is detected by the O2 sensor 64.

Further, the temperature of the exhaust gas initially discharged from the diesel engine 1o to the trap 2° is detected by a temperature sensor 66, and the pressure thereof is detected by a pressure sensor 68. The operation sensor 72 detects whether or not the light control switch 7o, which turns on and off the headlights, is operated.

The ECU 34 uses the above opening sensor 52. pressure sensor 54,
Temperature sensor 56, load sensor 58, rotation speed sensor 60.
It is configured so that the diesel engine 10 can be controlled based on various detection signals from the vehicle speed sensor 82, 02 sensor 64, temperature sensor 66, pressure sensor 68, and operation sensor 72, and the following controls can be performed. .

The ECU 34 can control the chopper circuit 32 so that the chopper circuit 32 supplies ignition current to the heater 26 when the pressure loss of the filter 24 exceeds a predetermined value.

In this embodiment, this control is performed based on detection signals from the load sensor 58, rotational speed sensor 60, and pressure sensor 68.

The IJOM of the ECU 34 stores the characteristic P shown in diagram t53, in which the horizontal axis represents the engine rotational speed detection value N, and the vertical axis represents the engine load detection value. The ECU 34 includes a load sensor 58 and a rotation speed sensor 60.
Determine the exhaust pressure reference value PO using the characteristic P from the detection signal of
It is possible to control the chopper circuit 32 so that the chopper circuit 32 supplies the ignition current to the heater 2B when the detected value of the pressure sensor 68 exceeds this reference value PO.

Further, the ECU 34 can control the chopper circuit 32 to prohibit the supply of ignition current to the heater 26 until the trap 20 is warmed by exhaust gas, and to start supplying the ignition current for the first time when the trap 20 is warmed up.

Detection signals from the temperature sensor 66 and the temperature sensor 56 are used for this control, and the ECU 34 detects that when a predetermined time has elapsed after starting the diesel engine IO, the temperature of the exhaust gas supplied to the trap 20 has exceeded a predetermined value f1. When it is confirmed by the detection signal of the temperature sensor 66 that the temperature of the engine h cooling water is higher than a predetermined value, it is determined that the trap 20 has warmed up and the supply of ignition current to the heater 26 is started. 1t (I can control it.

Note that when controlling the start of the ignition current to the heater 26,
The ECU 34 can confirm in advance that the integrated value of the vehicle speed and the integrated value of the engine speed (for example, 200,000 revolutions) each exceed a predetermined value and that the pressure sensor 68 does not malfunction.

Then, the ECU 34 controls the flow rate of the exhaust gas flowing through the deck 20 by adjusting the opening degree of the exhaust flow rate control valve 44 so that the collected particulates ignited by the heater 26 are properly combusted.

Also, at this time, the ECU 34 outputs the 02 sensor 64. By adjusting the opening degree of the exhaust flow rate control valve 44 in accordance with the detection signal of the temperature sensor 66, the flow velocity of the exhaust gas flowing through the trap 20 can be reduced, thereby preventing the trap 20 from melting.

Further, the ECU 34 controls the value of the ignition current so that the value correlates with the power supply voltage when the headlamp is turned on.

In this embodiment, since the output voltage of the battery 36 depends on the engine rotation speed, the value of the ignition current supplied to the heater 26 is controlled according to the detection signal of the rotation speed sensor 60, that is, the engine rotation speed. That is, when the engine speed is low, the duty ratio of the ignition current is decreased and its value is reduced, and when the engine speed is high, the duty ratio is increased and its value is increased. The value of the fire current is controlled by its duty ratio according to the characteristic 100 in FIG. As a result, the output voltage of the battery 36 is controlled to be substantially constant.

In addition, the ECU 34 controls the heater 26 when the headlamp is turned on.
The value of the ignition current can be gradually increased or decreased.

The ECU 34 of this embodiment detects the lighting state of the headlamp based on the detection signal of the operation sensor 72, and gradually controls the duty ratio of the ignition current to increase or decrease over time as shown by the characteristic 102 in FIG. are doing. Furthermore, EC
U34 is electric heat 1130-1, 30-2, 30-3, 30
-4, 30-5, 30-6, 30-7, 30-8 are energized one by one in the prescribed order, and the last heating wire 3
The duty of the switching transistors 38 and 40 of the circuit 32 can be controlled so that the value of the ignition current is gradually reduced when the transistor 0 is de-energized.

The present embodiment has the above configuration, and its operation will be explained below.

FIG. 6 shows a main routine explaining the entire process of the ECU 34, in which processes including a control process for the diesel engine 10 (step 200) and a regeneration process for the wrap 20 are repeatedly performed.

In step 200, the basic fuel injection amount and injection timing are first determined based on the amount of depression of the accelerator pedal, that is, the lever opening of the injection pump and the engine rotational speed. The basic injection amount and injection timing are corrected based on the engine coolant temperature, intake air temperature, etc., and the output of the diesel engine 10 is controlled using these corrections.

During operation of diesel engine IO, exhaust flow IL! li1
The control valve 44 is closed and the exhaust gas is guided to the trap 20 side, so that the particulates contained in the exhaust gas gradually flow from the upstream surface of the filter 24 toward the downstream direction.
is collected in the filter 24 and stored in the filter 24.

As a result, clean gas containing no particulates is emitted from the vehicle, thereby preventing any negative impact on the surrounding environment.

In step 202, the process shown in FIG. 7 is first performed.

In the processing for the seventh cause, it is determined whether or not the filter 24 collects MI particles that are rrI-certified in the following manner.

In Figure t57, the ECU 34 determines whether the pressure loss of the filter 24 exceeds a predetermined value by using the characteristic P in Figure 3 from the detection signals of the load sensor 58 and rotational speed sensor 6o to determine the reference value. po is determined, and it is determined whether the detected value of the pressure sensor 68 exceeds this reference value Po (step 300).

When it is determined that the detected value of this good pressure sensor 68 exceeds the reference value PO, the pressure loss of the filter 24 has exceeded the predetermined value and a predetermined amount of particulates have been collected in the filter 24, resulting in an output loss of the diesel engine IO. has increased to a certain extent.

Next, the ECU 34 determines whether the integrated rotational speed value and the integrated vehicle speed value of the diesel engine 10 each exceed a set value (steps 302 and 304).

When it is determined in Stella 7' 302 that the calculated value of the diesel engine 10 (7) revolutions a8 does not exceed the set value, the determination is made in step 300, and in step 304, it is determined that the vehicle speed integrated value does not exceed the set value. When this happens, the determinations in steps 300 and 302 are once invalidated.

In step 306, the determinations in steps 300 and 302 that were once invalidated in steps 302 and 304 are examined. Note that when there is no risk that the reference value PO used in step 300 will be destroyed, step 302 is performed.
, 304.306 are preferably omitted.

In this way, when it is detected that a certain amount of particulates have accumulated in the filter 24, if the collection of particulates continues, the loss on the exhaust side increases and the output of the diesel engine 1O decreases, so the filter 24 The fine particles collected by the heater 24 are ignited and burned by the heater 26 in the following manner.

Tree II! In this case, the supply of ignition current to the heater 2B is inhibited until the trap 20 is warmed up by the exhaust air, and is only started once the trap 20 is warmed up.

In FIG. 8, it is first confirmed that the exhaust system has been warmed up after a predetermined period of time has passed since the diesel engine IO was started (step 400).

Next, it is confirmed by the detection signal of the temperature sensor 66 that the temperature of the exhaust gas discharged from the diesel engine IO into the trap 20 is higher than a predetermined temperature (step 402
).

Furthermore, it is confirmed from the detection signal of the temperature sensor 56 that the cooling water temperature of the diesel engine IO is 60° C. or higher (step 404).

As described above, in this embodiment, the trap 20 is warmed up when a predetermined period of time has elapsed since the start of four-turn rotation of the diesel engine lO, the exhaust temperature has reached a predetermined temperature or higher, and the cooling water temperature has reached 60°C or higher. After that, the ignition combustion process of the particulates collected by the filter 24 is started (step 406). Note that a temperature sensor is provided to directly detect the temperature of the trap 20 or the temperature of the exhaust system. The signal may be used to confirm that the trap 20 has been warmed up.

As described above, in this embodiment, combustion of the particulates collected in the filter 24 is started after the trap 20 is warmed up, so thermal stress is prevented from occurring in the casing 22 and the filter 24, and Corruption is avoided.

Next, the process of step 406 will be explained.

In FIG. 9, the process of step 406 is performed by the filter 24
Process for controlling ignition of fine particles collected in (step 5)
00) and a process for controlling the opening degree of the exhaust flow rate control valve 44 (step 502), and both processes are started at the same time.

FIG. 10 shows the ignition process in step 500, in which first, whether or not the headlamp is lit is determined based on the detection signal of the operation sensor 72 (step eoo).

If it is determined that the headlamp is on, it is determined whether the rotation speed of the diesel engine 10 is high or low based on the detection signal of the rotation speed sensor 60. In this embodiment, when the rotation speed of the diesel engine 10 is 110011 rpm or more, it is determined that the rotation speed is high.
If it is less than that, it is determined that it is low (step 602).

Furthermore, when it is determined in step 600 that the headlights are not lit, the duty ratio of the ignition current supplied to the heater 26 is set to a large value (step 60).
4) Also, when it is determined that the engine speed is high when the headlights are on, the duty ratio of the ignition current is set to a medium value (step 60B), and it is determined that the engine speed is low when the headlights are on. When the duty ratio of the ignition current is set to a small value (step 608).

Thereafter, the supply of the ignition current with the duty ratio set as described above is started (steps 810 and 812).
).

When the supply of the ignition current with the duty ratio set in step 60B, -808 is started, the duty ratio is gradually increased as shown in FIG. 1゜30-2.30-3.3
0-4.30-5.30-6.30-7.30-8 are fired in a predetermined order (step 614).

At this time, the ignition time of the heater 26 is monitored, and if it is determined that a predetermined time has elapsed (step 61
B), ignition of the heater 213 is terminated (step 60
B), when the ignition of this heater 26 is completed, each heating wire 3
0-1.30-2.30-3.30-4.30-5.3
When lighting was performed in the order of 0-6.30-7.30-8, the duty ratio of the ignition current supplied to the last heating wire 30 was gradually reduced as shown in FIG.
L/I controlled.

Next, fr n is performed in step 502 of FIG.
/11n processing will be explained.

When the particulates collected by the filter 24 are ignited by the heater 26, the exhaust flow rate regulator and valve 44 provided in the exhaust passage 42 are temporarily opened to allow most of the exhaust to flow into the exhaust passage 42. This limits the amount of exhaust gas flowing into the trap 20.

As a result, the flow velocity of the exhaust gas flowing into the trap 20 is reduced, and the particulates collected in the filter 24 are smoothly ignited and burned.

Further, under a predetermined exhaust gas temperature condition where the oxygen concentration in the exhaust gas is high, the exhaust flow aim moderation valve 44 is forcibly controlled to open. This control is performed for the following reason.

If high-load operation such as steep climbing or high-speed driving is performed continuously with a sufficient amount of particulates collected in the filter 24, the exhaust temperature will become considerably high, and the oxygen concentration in the exhaust will decrease. It is small because the amount of fuel injected is large.

If the accelerator pedal is opened or opened halfway during this high-load operation, the oxygen concentration in the exhaust gas will rapidly increase because a large amount of air is being supplied to the diesel engine 10.

Therefore, since a large amount of oxygen is supplied to a place where the exhaust gas temperature is considerably high, the ignited collected particles are rapidly combusted.

As a result, there is a risk that the filter 24 will become hot and the trap 20 will melt.

Therefore, in this embodiment, when the oxygen concentration in the exhaust gas increases under the exhaust temperature condition where the exhaust gas is at a considerably high temperature, the valve 44 is forcibly opened and the amount of exhaust gas flowing through the trap 20 is reduced. . Note that the temperature of the exhaust gas is detected from the detection signal of the temperature sensor 66, and the oxygen concentration is detected from the detection signal of the 02 sensor 64.

By performing the above-described ignition process (step 500) and valve control process (step 502), the part of the particulate matter collected on the filter 24 at the most upstream side of the exhaust gas is ignited.

Since #n'J5 particulates are flammable and there is sufficient oxygen in the exhaust gas, the ignited collected particulates are ignited and the combustion of the collected particulates progresses toward the downstream of the exhaust. do.

When this combustion is completed, there is no remaining particulate phase in the fill 24, and as a result, the pressure loss in the trap 20 is reduced to the initial loss. That is, the playing cards 20 are regenerated and can be reused.

As explained above, according to this embodiment, when a predetermined amount of particles are implanted in the filter 24 and the pressure loss thereof exceeds a predetermined value, the collected particles are ignited, and the amount of captured particles and the pressure loss are increased. Since these correspond almost exactly, it is possible to regenerate the trap 20 at an optimal time.

In contrast, the engine speed integrated value, vehicle running IAi
If the regeneration timing of the playing cards 20 is determined only based on the PJ, engine operating time cumulative value, etc., the amount of particles collected will differ depending on the driving conditions, etc., and a large amount of particles will accumulate at the regeneration timing. If the collected particles are ignited at this time, the temperature of the trap 20 rises abnormally. As a result, the trap 20 suffers FII loss or the durability of the trap 20 decreases.

As described above, according to this embodiment, the trap 20 is activated at the optimal time.
Since the regeneration process is performed, it is possible to prevent the playing cards 20 from being damaged or to improve their durability.

In this embodiment, the pressure loss was detected by the electrical pressure sensor 68, but a pipe line is formed between the upstream side and the downstream side of the trap 20, and the trap 20 is placed in the pipe line. It is also possible to reduce costs by providing a mechanical switch such as a diaphragm that is activated when the pressure difference between the upstream side and the downstream side reaches a predetermined value, and using this instead of the pressure sensor 6B. This is suitable from the viewpoint of

Furthermore, according to this embodiment, after it is confirmed that the trap 20 has warmed up, the particulates that have been collected by the filter 24 are ignited, so that a large temperature difference can be prevented from occurring in the trap 20 part. be done. Therefore, it is possible to avoid the inconvenience that the playing cards 20 and the like are damaged due to thermal stress caused by this temperature difference, and therefore it is possible to improve the durability of the device.

Furthermore, according to this embodiment, when the trap 20 is regenerated when the headlamp is turned on, the battery 3
Since the ignition current with a duty ratio correlated to the output voltage of No. 6 is supplied to the heater 26, a decrease in illuminance of the headlamp can be prevented. Therefore, even if the regeneration process of the trap 20 is started while driving at night, good driving visibility is ensured, and therefore safe driving is possible.

It is also preferable to configure the device so that a voltage needle is provided to detect the output voltage of the buffer battery 36 and the duty ratio of the ignition current is controlled in accordance with the detection signal.

According to this embodiment, when the trap 20 is regenerated when the headlamp is turned on and the ignition current to the heater 26 is suddenly increased or decreased, such as when the ignition current is turned on or off, the increase or decrease is done gradually. The supply voltage to the headlamp does not fluctuate suddenly, so
Even if the regeneration of the trap 20 starts or ends when the headlamp is turned on, flickering of the headlamp light will not be visible to the driver. Therefore, there is no need for the driver to feel uneasy about the vehicle.

Further, according to the present embodiment, even if the oxygen concentration in the exhaust gas increases when the exhaust gas is under a predetermined exhaust temperature condition in which the exhaust gas is at a high temperature, the valve 44 is forcibly opened and the exhaust gas flows to the trap 20. Since the amount of particles is limited, abnormal combustion of the particulates collected in the trap 20 can be prevented. For this reason, trap 2
0 can be prevented from melting and the reliability of the device can be improved.

[Effects of the Invention] As explained above, according to the present invention, the collected particulates are ignited when the pressure loss of the filter, which almost exactly corresponds to the amount of collected particulates collected in the filter, exceeds a predetermined value. Therefore, it is possible to regenerate the trap at an optimal time.

Therefore, playing cards are not recycled after a large amount of fine particles have been collected, and this prevents the trap temperature from rising abnormally and damaging the trap or reducing its durability. As a result, a highly reliable device can be provided.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the overall configuration of an apparatus according to the present invention. Fig. 2 is an explanatory diagram of the configuration of the heater in Fig. 1, Fig. 3 is an explanatory diagram of the characteristics of the exhaust pressure reference value, Fig. 4 is a characteristic diagram showing the relationship between the ignition current and its duty ratio, and the t55 diagram is the elapsed time. Fig. t56, Fig. 7, Fig. 8, Fig. 9, and Fig. 1O are explanatory diagrams of control characteristics of duty conversion for
It is a flowchart figure explaining the control operation of U. 10---・Diesel engine, 20・・・・・trap, 24・・
・-Filter. 26・30・Heater. 32...1 chopper circuit, 34... ECU. 68...Φ pressure sensor. Agent Patent Attorney Jun Nakataka

Claims (1)

[Claims] (1) A trap including a filter that captures particulates contained in engine exhaust gas and a heater that ignites the particulates collected by the filter; a pressure loss detection means that detects pressure loss of the filter; and pressure loss detection means for detecting pressure loss. A particulate collection device comprising: a power supply circuit that supplies an ignition current to a heater when the pressure loss of the filter exceeds a predetermined value.