JP3598572B2 - Exhaust particulate purification equipment - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an exhaust particulate purification device that collects exhaust particulates (particulates) contained in exhaust gas of a diesel engine using a filter and burns the collected exhaust particulates to regenerate the filter.
[0002]
[Prior art]
In this exhaust particulate purification apparatus, exhaust particulates in exhaust gas are collected by a ceramic filter disposed in an exhaust passage of a diesel engine, and the amount (collected amount) of the collected exhaust particulates is detected and reproduced. The timing is determined (JP-A-6-26327). When the regeneration time is determined, the filter regenerates by burning the exhaust particulates attached to the filter.
[0003]
[Problems to be solved by the invention]
However, if the trapping amount to be regenerated is small, unburned residue and the like are generated, resulting in incomplete regeneration. If the trapping amount is large, the regenerating temperature rises excessively, causing problems such as filter cracking and erosion.
Therefore, it is necessary to regenerate the filter when the trapping amount becomes a value within a predetermined range. However, for some reason, for example, when a regeneration start condition other than the trapping amount is set, the condition is not satisfied for a long time. In the case where the reproduction cannot be performed due to a failure of the component to be reproduced or due to a failure of the component to be reproduced, the reproduction is started in an excessively collected state, and the above-described problem due to an excessive increase in the reproduction temperature occurs.
[0004]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to detect an over-collection state and not to perform regeneration at that time.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the exhaust gas is provided in an exhaust passage through which all exhaust gas from the upstream side passes at all times during operation of the diesel engine (1). A filter (7), a regenerating means (8 and an air pump not shown) for regenerating the filter by burning the exhaust particulates collected by the filter, and the regenerating means (8 and an air pump not shown) according to the amount of the exhaust particulates collected by the filter. In the exhaust particulate cleaning apparatus provided with a control means (3) for controlling the regenerating means, the control means includes a trapped amount detecting means (101 to 104) for detecting a trapped amount of the filter. When the amount of collected fine particles becomes equal to or more than the value indicating the excessive collection state, the regeneration of the filter by the regeneration unit is prohibited (105).
[0006]
According to the second aspect of the present invention, the filter (7) provided in the exhaust passage of the diesel engine (1) for collecting the exhaust particulates, and the filter is regenerated by burning the exhaust particulates collected by the filter. And a control means (3) for controlling the regenerating means in accordance with the amount of exhaust particulates collected by the filter. It includes a collection amount detection means for detecting an amount of particulate matter trapped in the filter (101-104), and a state determining means determines that due to a possible state reproducing said reproducing means, is the detected There the value of the reproduction range between the minimum collection amount and the highest amount of collection of the particulate collection volume requires regeneration, and the to be reproduced is capable state is determined by the state determining means Kiniwa, to perform the regeneration of said filter, said when the detected particulate collection amount is equal to or greater than said maximum collection amount or more is shown an over-collecting state value does not perform regeneration of the filter It is characterized in that way.
[0007]
According to the third aspect of the present invention, in the exhaust particulate cleaning apparatus according to the first or second aspect , a warning unit that issues a warning when the detected amount of trapped particulates is equal to or greater than a value indicating an excessive trapping state. 16, 108, 109). The symbols in parentheses of the above-mentioned means indicate the correspondence with specific means described in the embodiments described later.
[0008]
Operation and Effect of the Invention
According to the first to third aspects of the present invention, the regeneration of the filter is prohibited when the amount of trapped fine particles of the filter is equal to or greater than the value indicating the over-collection state. By not performing the regeneration, it is possible to eliminate problems such as filter cracking and erosion due to an excessive increase in the regeneration temperature.
[0009]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the overall configuration of an exhaust gas purification device for a diesel engine.
An air cleaner 2 is provided on the intake side of the diesel engine 1, and a hot-wire type flow sensor 3 for detecting the intake flow rate is provided in the middle of a flow path from the air cleaner 2 to the diesel engine 1.
[0010]
The exhaust pipe 4 of the diesel engine 1 is provided with an exhaust purification device 5. The exhaust gas purification device 5 has a housing 6 that communicates with the exhaust pipe 4, and the exhaust gas passes through the housing 6.
A filter 7 is disposed in the housing 6, and the filter 7 is made of a porous ceramic. Exhaust particulates in the exhaust gas are collected by passing the exhaust gas through the filter. An electric heater 8 is provided on the upstream end face of the filter 7, and ignites the exhaust particulates when the filter 7 is regenerated. At the time of regeneration of the filter 7, air necessary for combustion of exhaust particulates is supplied from an air pump (not shown). Therefore, the electric heater 8 and the air pump constitute a regenerating means for regenerating the filter 7 by burning the exhaust fine particles collected by the filter 7.
[0011]
Further, the exhaust gas purification device 5 is provided with a pressure sensor 9 for detecting an absolute pressure (front pressure) of the filter 7 on the diesel engine 1 side and a pressure sensor 10 for detecting an absolute pressure (back pressure) of the filter 7 on the exhaust side. Have been. Further, a temperature sensor 11 for detecting the temperature of exhaust gas flowing into the filter 7 from the diesel engine 1 and a temperature sensor 12 for detecting the temperature of exhaust gas flowing out of the filter 7 are provided.
[0012]
Then, signals from the sensors are input to an electronic control unit (ECU) 13. A CPU 14 is provided in the ECU 13, and each sensor signal is finally input to the CPU 14. The CPU 14 calculates a trapped amount of exhaust particulates to determine a regeneration timing, and executes a computation process for regenerating the filter 7 at the time of the regeneration timing determination.
[0013]
The CPU 14 also performs a process of turning on the warning lamp 15 when it is determined that the filter 7 is in the over-collection state, to warn the driver.
The operation of the above configuration will be described with reference to the flowchart of FIG.
First, sensor values from the sensors 3 and 9 to 12 are fetched (step 101). The processing of steps 102 and 103 is performed based on the acquired sensor values. That is, the pressure difference ΔP (= P1−P2) of the filter 7 is obtained by subtracting the pressure P2 detected by the pressure sensor 10 from the pressure P1 detected by the pressure sensor 9 (step 102). The gas flows into the filter 7 from the intake air mass flow rate G detected by the flow rate sensor 3, the pre-pressure P1, and the average temperature Tex of the incoming gas temperature detected by the temperature sensor 11 and the outgoing gas temperature detected by the temperature sensor 12. The volume flow rate V to be calculated is determined by f (G, Tex, P1) (step 103). This function f is a function for converting an intake air mass flow rate into an exhaust volume flow rate based on the temperature and pressure of exhaust gas.
[0014]
Next, the trapped amount PMq of exhaust particulates is calculated from g (ΔP, V) from the filter differential pressure ΔP and the volume flow rate V flowing into the filter 7 (step 104). This function g is basically set 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 airflow resistance, that is, the amount of clogging of the filter, which is used as the trapping amount.
[0015]
Thereafter, it is determined whether or not the obtained trapping amount PMq is within a regeneration range between the minimum trapping amount PMq1 and the maximum trapping amount PMq2 at which the filter can be stably regenerated, that is, within a regeneration determination area. Is determined (step 105).
If the trapping amount is still small and the trapping amount PMq has not reached the minimum trapping amount PMq1, the process returns to step 101 via steps 105 to 107 and repeats the above-described arithmetic processing.
[0016]
Thereafter, when the trapping amount PMq falls within the above-described range of the regeneration determination area, the determination in step 105 is YES, and it is determined whether the system is in a reproducible system state (step 106). The regenerable system state is, for example, a component that performs regeneration when the engine speed calculated from the hot-wire flow sensor 3 is equal to or greater than a predetermined value, and the filter temperature immediately before regeneration determined from the gas input temperature of the temperature sensor 11 is equal to or greater than a predetermined value. (Electric heater 8, air pump, etc.) are not in a regeneration prohibited state due to a failure (this process is not shown, but failure detection is performed in CPU 14).
[0017]
When the determination in step 106 is YES, the reproduction control is performed in the reproduction control routine 200. In the regeneration control routine 200, a known process of operating the electric heater 8 and an air pump (not shown) to burn the exhaust fine particles collected by the filter 7 is performed.
Even if the trapping amount PMq has reached the value in the regeneration determination area in step 105, if the system is not in a reproducible system state, the determination in step 106 will not be YES, and the regeneration control will not be performed. I can't. If such an unreproducible system state continues for a long time and the trapping amount PMq exceeds the maximum trapping amount PMq2, the determination in step 105 becomes NO, and the determination in next step 107 becomes YES. , The warning light 16 is turned on to notify the driver of the over-collection state.
[0018]
After that, since the value of the trapping amount PMq increases, the value does not become a value in the above-described regeneration determination region, and the regeneration process of the filter 7 is not performed. That is, when the trapping amount PMq becomes equal to or more than the maximum trapping amount, the regeneration of the filter 7 is prohibited.
When the regeneration is prohibited, the filter 7 needs to be replaced or the like. However, until the filter is clogged, the clogging of the filter progresses rapidly. Thereafter, the engine may be stopped by stopping the fuel supply to the engine.
[0019]
In the above embodiment, the regeneration start condition other than the trapping amount, that is, the condition in which the system state determination process of step 106 is provided, is not provided. Even in the case where the reproduction is started, if the reproduction start timing is delayed due to a failure of a component to be reproduced, an over-collection state may occur, and the present invention is applied to such a case. be able to.
[0020]
In the above embodiment, each step shown in the flowchart of FIG. 2 is grasped as a function realizing means for realizing each function, and is configured with a hardware logic configuration corresponding to those functions. You may do so.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a diesel engine exhaust gas purification apparatus showing one embodiment of the present invention.
FIG. 2 is a flowchart showing a calculation process of a CPU 14 in FIG.
[Explanation of symbols]
1. Diesel engine, 2. Air cleaner, 3. Hot wire flow sensor,
5 exhaust gas purifier, 7 filter, 8 electric heater, 9, 10 pressure sensor,
11, 12: temperature sensor, 13: ECU, 14: CPU, 15: warning light.

Claims (3)

A filter provided in an exhaust passage through which all the exhaust gas from the upstream side passes at all times during operation of the diesel engine, and a filter for collecting exhaust particulates, and the filter is regenerated by burning the exhaust particulates collected by the filter. And a control means for controlling the regenerating means according to the amount of exhaust particulates collected by the filter,
The control means includes a trapping amount detecting means for detecting a trapping amount of the fine particles of the filter, and when the detected trapping amount of the filter becomes equal to or more than a value indicating an excessive collecting state, An exhaust particulate purification device characterized in that regeneration of a filter is prohibited. A filter provided in the exhaust passage of the diesel engine to collect exhaust particulates; a regeneration unit configured to burn the exhaust particulates collected by the filter to regenerate the filter; and a filter for exhaust particulates collected by the filter. Control means for controlling the regeneration means according to the amount, in the exhaust particulate purification device,
The control unit includes a trapping amount detecting unit that detects a trapping amount of the fine particles of the filter, and a state determining unit that determines that the filter can be regenerated by the regenerating unit. When the collection amount is within a regeneration range between the minimum collection amount and the maximum collection amount that require regeneration, and the state determination unit determines that the regeneration is possible, The filter is to be regenerated, and when the detected amount of trapped fine particles is equal to or more than the value indicating the excessive collection state that is equal to or more than the maximum collection amount, the filter is not regenerated. Exhaust particulate purification equipment. 3. The exhaust particulate cleaning device according to claim 1, further comprising a warning unit that issues a warning when the detected particulate collection amount is equal to or greater than a value indicating an excessive collection state.

Images