JPH0569312U - Particulate collection amount measuring device - Google Patents

Abstract

(57) [Abstract] [Purpose] Diesel particulate filter (DP
D) DPF durability by measuring the self-regeneration amount (self-burning amount) of particulates accumulated in F) to obtain the amount of particulate accumulation that changes depending on operating conditions, and correcting the set threshold that controls the filter regeneration time Try to. [Composition] Before and after the exhaust gas aftertreatment device 5 for collecting and burning particulates in exhaust gas, the exhaust aftertreatment device 5 is provided.
Concentration of oxygen in the exhaust gas flowing into the same aftertreatment device 5
Oxygen concentration sensors 10 and 11 for outputting the concentration of oxygen contained in the treated exhaust gas flowing out from the exhaust gas aftertreatment device are arranged according to the difference in the outputs from the sensors 10 and 11. 5 was connected to the control means 8 for obtaining the particulate self-regeneration amount D1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a measuring device for measuring the amount of particulates collected in an exhaust gas aftertreatment device.

[0002]

[Prior Art]

 BACKGROUND ART An exhaust gas post-treatment device that purifies exhaust gas by collecting and burning particulates contained in exhaust gas is known. This device collects particulates in exhaust gas with a diesel particulate filter (DPF), and when a certain amount of them is accumulated, it is heated by a heater and burns the accumulated particulates to regenerate the DPF. Are doing.

Back pressure detection, direct detection, integration detection method, and the like are currently used to measure the amount of particulate collection in such an apparatus. Among them, the integration detection method is the engine speed. The accumulated amount of particulates per unit time is calculated from the accelerator opening and smoke concentration, which are load information, and integrated, and when the integrated value exceeds the set threshold value, the particulates are burned and the DPF It is playing.

[0004]

[Problems to be solved by the device]

 By the way, since particulate matter usually burns at around 700 ° C, it is difficult to burn it only with exhaust temperature, and it is heated and burned by a heating device such as a heater. It is set assuming the amount of particulates that may exist. However, some of the particulates may self-ignite and burn (self-regenerate) at a temperature (350 ° C) lower than the above-mentioned temperature (700 ° C) depending on the state, and the assumed particulate collection There is a gap between the volume and the actual particulate collection volume. Regarding the current threshold setting, the amount of particulates self-regenerating is not taken into consideration, so if the filter is burned based on the threshold set above, the filter will burn excessively, and the durability of the filter will be reduced. Causes a problem.

[0005]

[Means for Solving the Problems]

 Therefore, in the present invention, a pair of exhaust gas after-treatment devices for collecting and burning the particulates contained in the exhaust gas emitted from the engine exhaust system are arranged before and after the exhaust gas after-treatment device and flow into the exhaust after-treatment device. An oxygen concentration sensor that detects the oxygen concentration in the exhaust gas and the oxygen concentration contained in the treated exhaust gas that flows out from the exhaust gas post-treatment device is connected to each of the oxygen concentration sensors. We propose a particulate collection amount measuring device comprising a control means for obtaining the self-regeneration amount in the exhaust gas aftertreatment device based on the difference in the detected values.

[0006]

[Action]

 The oxygen concentration in the untreated exhaust gas flowing into the exhaust gas aftertreatment device and the oxygen concentration in the treated exhaust gas flowing out from the exhaust gas aftertreatment device are detected by the oxygen concentration sensor and output to the control means, The control means calculates the amount of self-regeneration (self-combustion amount) from the output difference, so by subtracting the amount of self-regeneration from the amount of particulate inflow into the exhaust gas aftertreatment device, the particulates collected in the diesel particulate filter are The amount of crate collection is calculated.

[0007]

【Example】

 Embodiments of the present invention will be described below. In FIG. 1, reference numeral 1 indicates a diesel engine. An exhaust gas post-treatment device 5 is arranged in the exhaust passage 2 of the engine 1 via a primafra 3 and an exhaust shut valve 4. An introduction path 7 connected to an air pump 6 is connected between the exhaust shutoff valve 4 and the exhaust gas aftertreatment device 5, and secondary air is introduced into the exhaust gas aftertreatment device 5 from this pump 6 at appropriate times. A bypass passage 12 is formed to bypass the exhaust shutoff valve 4 and the exhaust gas aftertreatment device 5, and a normally closed on-off valve 14 is attached to the bypass passage 12.

The exhaust shut-off valve 4 and the opening / closing valve 14 are connected to the controller 8. The output signal sent from the controller 8 closes the bypass passage 12 when the exhaust passage 2 is opened, and the bypass passage 12 when the exhaust passage 2 is closed. It is controlled so as to open 12, and regulates the inflow of exhaust gas into the exhaust gas post-treatment device 5.

The exhaust gas post-treatment device 5 is a diesel particulate filter which is a ceramic filter section having a honeycomb structure for collecting particulates (Pct) contained in the exhaust gas discharged from the exhaust manifold of the engine 1. The (DPF) 9 is the center, and an air-permeable heat shield member (not shown) and a heater, which is a heating device, are housed in the canning container.

Oxygen concentration sensors (hereinafter referred to as “O ₂ sensors”) 10 and 11 connected to the controller 8 are respectively arranged in the exhaust passages 2a and 2b located before and after the exhaust gas aftertreatment device 5, respectively. The sensors 10 and 11 and the controller 8 constitute a particulate collection amount measuring device 12.

The O ₂ sensor 10 detects the concentration of oxygen in the untreated exhaust gas flowing into the exhaust gas post-treatment device 5, and the O ₂ sensor 11 processes the exhaust gas after-treatment device 5 which has been treated. The oxygen concentration in the exhaust gas is detected, and the detection result is output to the controller 8 as oxygen concentration information.

A main part of the controller 8 is configured by a well-known microcomputer, and is connected to a power supply via a power supply circuit (not shown). The above-mentioned sensors 10 and 11 are connected to an input circuit (not shown) of the controller 8, and output signals from these sensors are fetched into the control circuit at appropriate times.

The storage means of the controller 8 is a writing program that can store a program for DPF regeneration processing as shown in FIG. 2 to FIG. It also has a dedicated ROM and non-volatile memory that stores data regardless of whether the engine main switch is on or off.

As described above, the controller 8 serves as the control device 100 of the particulate collection amount measuring device 12, as shown in FIG. 3, as a Pct emission amount calculation means 101, a Pct self-combustion amount calculation means 102, and a Pct collection amount. It has the functions of the amount calculation means 103 and the Pct collection amount region determination means 104.

The Pct emission amount calculation means 101 calculates the particulate amount per unit exhaust amount flowing into the exhaust gas aftertreatment device 5 from the engine speed Ne, the accelerator opening θ and the smoke concentration (Bosch smoke rate). , Pct self-combustion amount calculation means 102, O ₂ Se uptake the oxygen concentration information from the oxygen concentration information and O ₂ sensor 11 from the capacitors 10, self-combustion of particulates from the deviation of the oxygen concentration (oxygen consumption) To calculate. The Pct accumulation amount calculation means 103 calculates the particulate accumulation amount to be accumulated in the DPF from the deviation between the particulate emission amount and the particulate self-combustion amount, and the Pct accumulation amount region determination means 104 is included in the particulate compensation amount area determination means 104. It is determined whether or not the collection amount exceeds a preset threshold value, and the DPF reproduction signal ΔU is output according to the determination result.

Hereinafter, the control operation of the particulate matter collection amount measuring device 12 will be described according to the control program executed by the controller 8.

In step 1, the controller 8 receives output signals for the engine speed Ne and the accelerator opening θ. In step 2, the Pct emission amount C per unit displacement is calculated using the maps shown in FIGS. 2 (a) and 2 (b), and in step 3, the Pct emission amount C is integrated over time to obtain Pct per unit time. The emission amount, that is, the Pct emission amount C1 with respect to the unit time unit exhaust amount is calculated and stored. In Fig. 2 (a), the vehicle was run on a chassis dynamo under certain conditions, exhaust gas emitted per unit time was collected and filtered, and the degree of contamination of the filter paper was calculated using a reflected light measurement device. FIG. 2B is a Pct emission amount calculation map in which the Pct emission amount C is calculated with respect to the smoke emission concentration (Bosch smoke concentration) created by using the smoke emission concentration that is the test data value. FIG. 2B shows the engine rotation speed Ne. And a flue gas concentration calculation map showing flue gas concentration with respect to accelerator opening θ. In other words, the inflow amount C1 of Pct into the exhaust gas post-treatment device 5 per unit time and unit displacement is calculated by creating a map that calculates the Bosch smoke concentration% from the engine speed Ne and the accelerator opening θ. That is why.

When the inflow amount C1 of Pct into the exhaust gas aftertreatment device 5 is calculated, the process proceeds to step 4. In step 4, the oxygen concentration information D 1 and D 2 sent from the O ₂ sensors 10 and 11 is input. In step 5, the deviation between D 1 and D 2 is obtained, and the combustion amount due to self-ignition of particulates is obtained using FIG. D (self-regeneration amount) is calculated, and in step 6, the combustion amount D is integrated over time, and the Pct combustion amount D1 per unit time is calculated and stored. FIG. 4 shows the oxygen consumption which is the deviation between the oxygen concentration output value D1 contained in the exhaust gas flowing into the exhaust gas post-treatment device 5 and the oxygen concentration output value D2 contained in the exhaust gas flowing out from the exhaust gas post-treatment device. It is a map showing the Pct combustion amount D with respect to the amount (oxygen concentration).

When the Pct inflow amount C1 per unit time and the Pct combustion amount D1 per unit time are calculated, the difference between the two is calculated in step 7, and the Pct collection amount B to be accumulated in the DPF is calculated, and the step At 8, it is judged whether or not this collection amount B is equal to or more than the set threshold value S. When it is determined that the Pct collection amount B is equal to or more than the set threshold value, the process proceeds to step 9, the DPF regeneration signal ΔU is issued from the controller 8 to turn on the exhaust shut valve 4 and the opening / closing valve 14, and the heater and the like are activated. To be done. As a result, the shut valve 4 is closed, the on-off valve 14 is opened, and the DPF 5 is regenerated (forced combustion) (step 10). If the Pct collection amount B has not reached the threshold value S yet, the collection amount calculation in step 7 is performed until the collection amount B reaches the threshold value S (step 11).

As described above, the O ₂ sensors 10 and 11 are arranged in the exhaust passages 2a and 2b located on the inflow side and the exhaust side of the exhaust gas post-treatment device 5, and the oxygen concentration information sent from the sensors 10 and 11 is measured. Since the amount of particulate self-regeneration D (combustion amount due to self-ignition) is calculated from D1 and D2, the Pct amount B accumulated in the DPF during traveling can be detected more accurately, and the threshold value S can be set more accurately. It can be set appropriately.

[0021]

[Effect of the device]

 According to the present invention, since the threshold value set based on the test data can be corrected according to the operating state, there is no fear of excessively burning the DPF filter of the exhaust gas aftertreatment device, and the durability of the filter is improved. be able to.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a particulate collection amount measuring device according to an embodiment of the present invention.

FIG. 2 (a) is a particulate emission amount reference map used in the particulate collection amount measuring device of FIG. 1, (b).
3 is a map showing the inflow of particulates used in the particulate collection amount measuring apparatus of FIG.

FIG. 3 is a control block diagram of the particulate collection amount measuring device of the present invention.

4 is a map showing a characteristic of a particulate combustion amount used in the particulate collection amount measuring device of FIG. 1. FIG.

FIG. 5 is a flowchart of a DPF regeneration processing routine used in the particulate matter collection amount measurement device of FIG. 1.

[Explanation of symbols]

1 Engine 5 Exhaust Gas Aftertreatment Device 10, 11 Oxygen Concentration Sensor (O ₂ Sensor) 8 (100) Control Means 12 Particulate Collection Measurement Device

Claims (1)

[Scope of utility model registration request] 1. A pair of exhaust gas after-treatment devices for collecting and burning particulate matter contained in exhaust gas discharged from an exhaust system of an engine, the pair being arranged before and after the exhaust gas after-treatment device and flowing into the exhaust after-treatment device. Each oxygen concentration sensor that outputs the oxygen concentration in the exhaust gas and the oxygen concentration contained in the processed exhaust gas that flows out from the exhaust gas post-treatment device, and the oxygen concentration sensor that is connected to the output from the sensor A device for measuring the amount of particulate collection in the exhaust gas aftertreatment device according to the above difference.