JPH08284639A - Exhaust particulate purifying device - Google Patents

Abstract

PURPOSE: To prevent abnormal combustion at the time of recollection in a filter in which reformation is suspended by inhibiting collection on the filter, when regeneration of the filter is suspended, at least from generation of suspension until a prescribed time, namely till the filter in which regeneration is suspended is cooled sufficiently. CONSTITUTION: Filters 5, 7 are arranged on the exhaust pipe side of a diesel engine 1 and on the branch downstream side of the exhaust pipe in parallel to each other, and regenerating heaters 6, 8 are arranged upstream from each filter 5, 7. In the case where a collecting amount exceeds a prescribed value, for example, when the filter 5 is re-generated, air control valves 14, 15 are closed, combustion air is supplied to the filter 5, and also the electric heater 6 is heated so as to ignite and burn the collecting particulate on the filter 5. In the case where an IGSW 21 is turned off during regeneration of the filter 5, it is memorized in a non-volatile memory in a condition in which a regenerating flag is set. After that in the case where the IGSW 21 is turned on, it is inhibited by regenerating flag that the particulate is collected on the filter 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to exhaust particulate matter (particulates) contained in exhaust gas of a diesel engine.
The present invention relates to an exhaust particle purification device that collects exhaust gas using a filter and burns the collected exhaust particles to regenerate the filter.

[0002]

2. Description of the Related Art Generally, since exhaust gas of a diesel engine contains a large amount of exhaust particles, a filter for collecting exhaust particles is installed in the exhaust passage.
As the amount of exhaust particulates accumulated inside the filter increases with use, the air permeability gradually deteriorates and engine performance deteriorates.Therefore, it is recommended that the filter be regenerated periodically according to the amount of exhaust particulates collected. It has become. The filter regeneration means that exhaust particulate matter is burned and removed by operating a regeneration means such as an electric heater provided on an end surface of the filter or an air pump for supplying air required for burning exhaust particulate matter.

Further, in such an exhaust emission control device,
Japanese Unexamined Patent Publication No. 6-101450, Japanese Utility Model Laid-Open No. 3-43519
In the publication, in order to prevent the reproduction from being interrupted by turning off the ignition switch (IGSW) during the filter reproduction, even if the IGSW is OFF during the reproduction.
There is disclosed a device that continues engine operation and continues regeneration even if F is given.

[0004]

However, in the above-described filter regenerator, the engine operation is continued while regeneration is continued even after the IGSW is turned off, which is a safety problem. Therefore, it is conceivable to interrupt the reproduction immediately after turning off the IGSW and continue the reproduction after turning on the IGSW next time. However, since the exhaust particulates in the vicinity of the heater are burning, the combustion cannot be propagated to the exhaust particulates in the unburned downstream region, and the regeneration cannot be performed after the IGSW is turned on. Therefore, it is necessary to collect again for regeneration.

However, after the IGSW is turned on, when the collection is started by the regeneration interruption filter, if the IGSW off time is short, the internal temperature of the filter is high and abnormal combustion occurs, which causes the filter to be melted and damaged. The present invention has been made in view of the above problems, and an object thereof is to prevent abnormal combustion at the time of recollection of a filter whose regeneration has been interrupted.

[0006]

In order to achieve the above object, in the invention described in claim 1, the exhaust gas passage of the diesel engine (1) is selectively switched between the first and second passages. A switching means (12, 13) and a filter (5, 7) installed in the first flow path for collecting exhaust particulates in exhaust gas when the first flow path is selected by the switching means. ), A regeneration means (2, 6, 8) for regenerating the filter by burning the exhaust particulates collected by the filter, and when the exhaust particulates collected by the filter reach a predetermined amount, An exhaust particulate purifying apparatus comprising: a control means (3) for controlling the switching means to switch the exhaust flow path to the second flow path and for regenerating the regenerating means. When the regeneration of the filter is interrupted Predetermined time from the time when at least the interruption occurred is characterized by having a prohibiting means for prohibiting the collection at the filter (102-111).

According to a second aspect of the present invention, in the exhaust particulate purifying apparatus according to the first aspect, the prohibiting means maintains the exhaust passage in the second passage and collects it in the filter. The feature is that it is prohibited. In the invention according to claim 3, the first and the first exhaust passages are installed in the exhaust gas flow passage of the diesel engine (1) and are respectively divided into two branched passages to collect the exhaust fine particles in the exhaust gas. 2 filters (5, 7) and switching means (12, 1) for switching the two channels to a collection channel and a regeneration channel.
3), and regeneration means (2, for regenerating the exhaust particulates collected by the filter installed in the one of the first and second filters which is the regeneration flow path by the switching means).
6 and 8), and when the amount of exhaust particulates collected by the filter in the collection channel reaches a predetermined amount, the switching means is controlled to switch between the collection channel and the regeneration channel and the regeneration is performed. And a control means (3) for performing a regenerating operation by means, wherein the control means regenerates the filter when the regeneration is interrupted, at least for a predetermined time from when the interruption occurs. Prohibition means (102 to 111) for inhibiting collection in the filter in which regeneration is interrupted by using the one in which the interrupted filter is installed as a regeneration flow path, and collecting flow by controlling the switching means when the predetermined time has elapsed. It is characterized by having means (112) for switching between the passage and the regeneration passage.

According to a fourth aspect of the present invention, in the exhaust particulate purifying apparatus according to any one of the first to third aspects, the regeneration interruption of the filter is performed by turning off an engine key switch (21) of the regeneration means. It is caused by the stoppage of the operation, and the prohibiting means prohibits the trapping by the filter which has suspended the regeneration for a predetermined time after the engine key switch is turned on.

According to a fifth aspect of the present invention, in the exhaust particulate purifying apparatus according to the fourth aspect, a non-volatile storage means for non-volatilely storing that the regeneration interruption of the filter has occurred even when the engine key switch is off ( A non-volatile memory), and the prohibiting means prohibits collection by the filter in which the reproduction is interrupted based on the storage state of the non-volatile storage means.

The symbols in parentheses for the above means are as follows:
It shows a correspondence relationship with a specific means described in the embodiments described later.

[0011]

According to the first and second aspects of the present invention, when the regeneration of the filter is interrupted, the collection by the filter is prohibited at least for a predetermined time from the time when the interruption occurs. Therefore, while the regeneration interrupted filter does not collect in the filter while it cools sufficiently,
It is possible to prevent abnormal combustion at the time of recollection of the filter whose regeneration has been interrupted.

According to the third aspect of the present invention, in the dual type exhaust particulate purifying device which alternately collects and regenerates, the regeneration interrupted filter is installed for a predetermined time after the regeneration interruption occurs. One is the regeneration channel, and the collection channel and the regeneration channel are switched when a predetermined time has elapsed. Therefore, since the filter for which the regeneration is interrupted moves to the collection state after a predetermined time, it is possible to restart the collection regardless of the regeneration state at the time of the interruption of the regeneration, and properly perform the alternate operation of the collection and regeneration thereafter. it can. In other words, if the collection amount of the collection filter reaches a predetermined value and the flow path is switched after the passage of a predetermined time and the collection of the filter that was interrupted at that point is restarted, the regeneration is interrupted. The collection ability varies depending on the regeneration state at the time. At this time, if the other filter is used for regeneration, the collection is continued even though the collection capacity is at its limit, and proper collection cannot be performed. Therefore, such a problem can be prevented by shifting the filter of which the regeneration is suspended to the collecting state after a predetermined time.

According to the fourth and fifth aspects of the present invention, the trapping by the filter whose regeneration is interrupted at the time after the engine key switch is turned on is prohibited. Therefore, by using the predetermined time after the engine key switch is turned on, it is possible to sufficiently secure the cooling time of the filter for which the regeneration is interrupted, without measuring the time from the time when the regeneration of the filter is interrupted.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an overall configuration diagram of an exhaust emission control device for a diesel engine. On the exhaust pipe side of the diesel engine 1, a filter 5 for collecting exhaust particulates to be exhausted
And the filter 7 are provided in parallel on the branch downstream side of the exhaust pipe. On the upstream side of the filters 5 and 7, electric heaters 6 and 8 for igniting the collected exhaust particulates are provided. Then, the exhaust pipes merge again and are connected to the muffler 18. An air cleaner 10 is provided on the intake side of the diesel engine 1.

Exhaust gas switching valves 12 and 13 are provided at two branch portions of the exhaust pipe to switch the two branched flow passages to a collection flow passage and a regeneration flow passage. In FIG. 1, the flow path on the filter 7 side is a collection flow path, and the filter 7 is in a state of collecting exhaust particulates in the exhaust. Air pump (A /
The discharge side of P) 2 is connected to the upstream side of the filters 5 and 7 through the air control valves 14 and 16, and the air cleaner 9 for the air pump is provided on the suction side of the air pump 2.

The downstream sides of the filters 5 and 7 are open to the atmosphere via the air control valves 15 and 17. The air control valves 14 to 17 are for configuring a flow path for supplying combustion air to the filter to be regenerated, and in FIG. 1, the air control valve 14 from the air pump 2 is used to regenerate the filter 5 side. , Filter 5, air control valve 15, and
An air flow path that opens to the atmosphere is configured.

Further, the pressure sensors 4a and 4b for detecting the differential pressure generated in the filter, and the engine speed sensor 1
1, and an exhaust temperature sensor 20 for detecting the exhaust temperature is provided. When the IGSW 21 is turned on, the ECU 3 is based on these input signals, and based on these input signals, the air pump 2, the electric heaters 6 and 8, the exhaust switching valves 12 and 13, the air control valve 1 described above.
The arithmetic processing which controls 4-17 etc. is performed. Also EC
An EEPROM is provided in the U3 as a non-volatile memory.

The operation of the above structure will be described with reference to the flowchart of FIG. First, when the IGSW 21 is turned on to supply power, the ECU 3 is put into an operating state, and the arithmetic processing shown in FIG. 2 is executed. First, the in-reproduction flag for the filters 5 and 7 is read from the nonvolatile memory provided inside the ECU 3 (step 101), and it is determined whether or not the in-reproduction flag for any of the filters is set (= 1) ( Step 102). When the during-reproduction flag is set, it indicates that the filter corresponding to the during-reproduction flag was interrupted by the IGSW 21 being turned off during the previous operation.

When none of the reproducing flags is set, the information for identifying the filter collected at the end of the previous operation is read from the non-volatile memory and the collection by the collected filter is restarted. To do so, the states of the exhaust switching valves 12 and 13 are set (step 10).
3). After that, the amount of collection by the collection filter is calculated (step 104). The calculation of this collection is performed as follows using a known arithmetic expression. First, the signals from the engine speed sensor 11 and the exhaust temperature sensor 20 are input, and the volume flow rate V of the exhaust gas is obtained from V = f (Ne, Tex) from the engine speed Ne and the exhaust temperature Tex.

Further, the differential pressure ΔP of the collecting filter is set to the pressure value P1 from the upstream pressure sensor 4a and the downstream pressure sensor 4b.
The differential pressure ΔP = P1−P2 is obtained from the pressure value P2 from Then, based on the differential pressure ΔP and the exhaust volume flow rate V, the trapped amount of exhaust particulates is determined by g (ΔP, V). This function g is basically set so as to obtain a value obtained by dividing the differential pressure ΔP by the volume flow rate V. The value obtained by using this function indicates the ventilation resistance, that is, the clogging amount of the filter, which is taken as the collection amount.

Then, it is judged whether or not the collected amount has reached a predetermined value (that is, a limit value requiring regeneration) (step 105). The above collection amount calculation process is repeated until the collection amount reaches a predetermined value. When the trapped amount reaches a predetermined value, the trapped filter and the regenerated filter are switched (step 106). Specifically, the exhaust switching valves 12 and 13 are switched and driven.
Also, a reproducing flag indicating that the filter that has been collected up to that time is to be reproduced is set. This playing flag is stored in a non-volatile memory.

After that, the filter is reproduced (step 107). In this regeneration process, the air control valves 14 to 17 are driven to form a flow path for supplying combustion air to the filter to be regenerated, and the electric heater provided in the filter to be regenerated is energized.
Operate the air pump 2. This reproduction processing is performed for a predetermined reproduction time, and it is determined whether reproduction is completed (step 10).
8), the previously set reproducing flag is reset (= 0). Then, the process returns to step 104, and the collection amount is calculated for the filter in the collection state. Thereafter, the above-mentioned collection and regeneration processes are alternately repeated for each filter.

As described above, the reproducing flag is set until the reproducing process is completed for the filter to be reproduced. Therefore, even if the IGSW 21 is turned off during the reproducing process and the reproducing process is interrupted, the non-volatile memory does not store it. It is stored with the reproducing flag set. It should be noted that the playback interruption is IGS
This is caused by stopping the operation of the electric heater and the air pump when W21 is turned off.

Then, the reproduction process is interrupted and the next IGSW
When 21 is turned on, the determination is YES when step 102 is reached due to the reproducing flag stored in the nonvolatile memory. In this case, in order to prohibit the collection by the filter for which the regeneration is interrupted, the exhaust switching valves 12, 1 are arranged so that the collection is performed by the other filter, that is, the filter collected when the IGSW 21 is off.
The state of 3 is set (step 110). In this case, the filter for which reproduction has been interrupted is in a dormant state in which nothing is done.

When this state continues for T1 time (time until the filter is naturally cooled, for example, a time period of 1 minute to 20 minutes), it is judged that the temperature of the filter for which the regeneration is suspended has sufficiently decreased (step 111). Then, the exhaust switching valves 12 and 13 are switched and driven in order to perform collection by the filter whose regeneration is interrupted (step 112). Therefore, thereafter, the collection is carried out by the filter for which the regeneration is interrupted, and when the collected amount reaches a predetermined value, the regeneration is carried out.

In the above-mentioned embodiment, the collection of the exhaust particulate and the regeneration of the filter are alternately performed by the two flow paths, but only one of the flow paths, that is, the first flow path is provided. A filter is provided, and the other flow path, which is the second flow path, is used as a bypass flow path without a filter, exhaust particulates are collected in the first flow path, and an exhaust switching valve is used when the filter is regenerated. The exhaust gas may be bypassed to the second flow path, and the filter provided in the first flow path may be regenerated during that time.

Further, the collection prohibition time in the regeneration interruption filter is required to be sufficient for its natural cooling, and in the above embodiment, the operation of the ECU 3 is stopped when the IGSW 21 is off, so the time after the IGSW 21 is turned on. However, in the case where the ECU 3 is operating even when the IGSW 21 is off, the time from the time when the reproduction interruption occurs may be measured.

In the above embodiment, each step shown in the flowchart of FIG. 2 is understood as a function realizing means for realizing each function, and has a hard logic configuration corresponding to those functions. You may make it comprised.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an exhaust emission control device for a diesel engine showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a calculation process of an ECU 3 in FIG.

[Explanation of symbols]

1 ... Diesel engine, 2 ... Air pump, 3 ... EC
U, 5, 7 ... Filter, 6, 8 ... Electric heater.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shoji Morita, 1-1, Showa-machi, Kariya city, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Inventor, Takayuki Toya, 1-1, Showa-cho, Kariya city, Aichi prefecture Within the corporation

Claims (5)

[Claims] 1. A switching means for selectively switching an exhaust gas flow path of a diesel engine between a first flow path and a second flow path; and a first flow path installed in the first flow path by the switching means. When is selected, a filter that collects exhaust particulates in the exhaust gas, a regenerating unit that burns the exhaust particulates that are collected by the filter to regenerate the filter, and an exhaust particulate that is collected by the filter When a predetermined amount is reached, the switching means is controlled to move the exhaust passage to the second passage.
And a control means for regenerating the regeneration means while switching to the flow path of the filter, the control means, when the regeneration of the filter is interrupted, at least for a predetermined time from the time when the interruption occurs, the control means captures with the filter. An exhaust particulate purifying device having a prohibiting means for prohibiting collecting. 2. The exhaust particulate matter according to claim 1, wherein the inhibiting means maintains the exhaust passage in the second passage to inhibit collection by the filter. Purification device. 3. A first and a second filter installed in each of the two branched passages in the middle of the exhaust gas passage of a diesel engine to collect exhaust particulates in the exhaust gas, and the two filters A switching means for switching the flow path to a collection flow path and a regeneration flow path, and a filter installed on the one of the first and second filters which is the regeneration flow path by the switching means. A regeneration unit that burns and regenerates exhaust particulates, and when the exhaust particulates collected by the filter in the collection channel reaches a predetermined amount, the switching unit is controlled to switch the collection channel and the regeneration channel. And a control unit for switching the regeneration operation by the regeneration unit, wherein the control unit is provided with a filter whose regeneration is interrupted when regeneration of the filter is interrupted, at least for a predetermined time from when the interruption occurs. You It has a prohibition means for prohibiting collection by a filter whose regeneration is interrupted as a raw flow path, and means for controlling the switching means to switch between the collection flow path and the regeneration flow path when the predetermined time has elapsed. A characteristic exhaust particulate purification system. 4. The interruption of the regeneration of the filter is caused by stopping the operation of the regeneration means by turning off the engine key switch, and the prohibiting means interrupts the regeneration for a predetermined time after the engine key switch is turned on. The exhaust particulate purifying device according to any one of claims 1 to 3, wherein collection by a filter is prohibited. 5. A non-volatile storage means is provided for non-volatilely storing that the reproduction interruption of the filter has occurred even when the engine key switch is off, and the prohibition means is based on the storage state of the non-volatile storage means. The exhaust particulate purifying apparatus according to claim 4, wherein collection by the filter is prohibited.