Exhaust gas treatment device for diesel engine
阅读说明:本技术 柴油发动机的排气处理装置 (Exhaust gas treatment device for diesel engine ) 是由 井上胜支 藤原正德 冈野宏昭 于 2019-06-04 设计创作,主要内容包括:本发明提供一种能够进行准确的灰烬堆积量的推定的柴油发动机的排气处理装置。在DPF(2)的再生处理结束后,基于从DPF(2)的再生处理的结束时起到追溯规定时间的追溯时为止的再生即将结束之前的期间存储于存储装置(6)的所述压差和排气流量的数据,通过灰烬堆积量推定装置(7)推定DPF(2)的灰烬堆积量。优选地,电子控制装置(20)基于灰烬堆积量的推定值达到了规定的警报必要值的情况,通过警报装置(8)发出警报。(The invention provides an exhaust gas treatment device for a diesel engine, which can estimate the ash accumulation amount accurately. After the regeneration process of the DPF (2) is finished, the ash accumulation amount of the DPF (2) is estimated by an ash accumulation amount estimation device (7) on the basis of the data of the pressure difference and the exhaust gas flow rate stored in a storage device (6) during a period from the end of the regeneration process of the DPF (2) to a retrospective time traced back for a predetermined time immediately before the regeneration is finished. Preferably, the electronic control device (20) issues an alarm by the alarm device (8) based on the fact that the estimated value of the ash deposition amount has reached a predetermined alarm necessary value.)
1. An exhaust gas treatment device for a diesel engine,
comprising:
a DPF (2) disposed on the exhaust path (1);
a PM accumulation amount estimation device (4) that estimates the amount of PM accumulated in the DPF (2); and
an electronic control device (20),
the electronic control device (20) performs regeneration processing of the DPF (2) based on the condition that the PM accumulation amount of the DPF (2) reaches a specified regeneration necessary value,
the exhaust gas treatment device is provided with: an exhaust gas temperature sensor (38); a differential pressure sensor (3); an exhaust gas flow rate calculation device (9); a storage device (6); a timing device (5); and an ash deposition amount estimation device (7),
data on a differential pressure between an exhaust gas inlet side and an exhaust gas outlet side of a DPF (2) detected by a differential pressure sensor (3) and an exhaust gas flow rate calculated by an exhaust gas flow rate calculation device (9) is stored in a storage device (6) (S3), and after a regeneration process of the DPF (2) is completed (S5), an ash accumulation amount of the DPF (2) is estimated by an ash accumulation amount estimation device (7) on the basis of the data on the differential pressure and the exhaust gas flow rate stored in the storage device (6) immediately before the regeneration is completed from the completion of the regeneration process of the DPF (2) to a retrospective time traced back by a predetermined time (S6).
2. The exhaust gas treatment device of a diesel engine according to claim 1,
has an alarm device (8),
the electronic control device (20) issues an alarm by the alarm device (8) based on the fact that the estimated value of the ash accumulation amount has reached a predetermined alarm necessary value.
3. The exhaust gas treatment device of a diesel engine according to claim 1 or 2,
having an air flow sensor (22), an atmospheric pressure sensor (40) and a fuel supply map (15),
an electronic control device (20) calculates the exhaust gas flow rate by an exhaust gas flow rate calculation device (9) based on the intake air flow rate measured by an air flow sensor (22), the atmospheric pressure detected by an atmospheric pressure sensor (40), the differential pressure detected by a differential pressure sensor (3), and the fuel supply amount measured by a fuel supply map (15).
4. The exhaust gas treatment device of a diesel engine according to claim 1 or 2,
having an air flow sensor (22),
an electronic control device (20) regards the intake air flow rate measured by an air flow sensor (22) as an exhaust gas flow rate, and calculates the exhaust gas flow rate by an exhaust gas flow rate calculation device (9).
Technical Field
The present invention relates to an exhaust gas treatment device for a diesel engine, and more particularly, to an exhaust gas treatment device for a diesel engine capable of estimating an accurate ash deposition amount.
Background
Conventionally, an exhaust gas treatment device for a diesel engine includes: this device includes a DPF disposed on an exhaust path, a PM accumulation amount estimation device that estimates an accumulation amount of PM accumulated in the DPF, an exhaust gas temperature increasing device, and an electronic control device that performs a DPF regeneration process based on a case where an estimated value of the PM accumulation amount of the DPF reaches a predetermined regeneration necessary value (see, for example, patent document 1).
Patent document 1: japanese patent laid-open No. 2006-105056 (refer to FIGS. 1-4)
In the device of patent document 1, immediately after the DPF regeneration process is completed, the electronic control unit estimates the amount of ash accumulation based on the differential pressure between the exhaust gas inlet side and the exhaust gas outlet side of the DPF, but immediately after the DPF regeneration process is completed, the differential pressure and the exhaust gas flow rate greatly fluctuate due to fluctuations in the engine load and the engine speed, and it is difficult to estimate the accurate amount of ash accumulation.
Disclosure of Invention
The present invention addresses the problem of providing an exhaust gas treatment device for a diesel engine, which can estimate the amount of ash deposition accurately.
In the present invention, after the end of the DPF regeneration process, the ash deposition amount of the DPF is estimated by the ash deposition amount estimation device based on the data of the differential pressure and the exhaust gas flow amount stored in the storage device immediately before the end of the regeneration from the end of the DPF regeneration process to the retrospective time retrospectively traced by a predetermined time.
In the present invention, it is preferable that the electronic control device issues an alarm by the alarm device based on a case where the estimated value of the ash deposition amount reaches a predetermined alarm necessary value.
According to the present invention, by maintaining the exhaust gas temperature within the predetermined range immediately before the end of regeneration, variations in the pressure difference and the exhaust gas flow rate are reduced, and the PM that hinders estimation of the ash deposition amount is almost completely burned, so that the ash deposition amount can be accurately estimated.
Drawings
Fig. 1 is a schematic diagram of an engine according to an embodiment of the present invention.
Fig. 2 is a flowchart of processing of the electronic control device of the engine of fig. 1.
Description of the reference numerals:
1: exhaust path
2:DPF
3: differential pressure sensor
4: PM deposit amount estimation device
5: time-piece
6: storage device
7: ash deposition amount estimation device
8: alarm device
9: exhaust flow rate calculation device
15: fuel supply map
19: exhaust temperature rising device
20: electronic control device
22: airflow sensor
38: DPF inlet side exhaust gas temperature sensor
40: atmospheric pressure sensor
S3: storing
S5: end of regeneration process
S6: estimating the amount of ash accumulation
Detailed Description
Fig. 1 and 2 are diagrams illustrating an engine according to an embodiment of the present invention, and in this embodiment, a vertical water-cooled inline four-cylinder diesel engine having an exhaust gas treatment device will be described.
The outline of the engine working machine is as follows.
As shown in fig. 1, the engine includes: a
The outline of the intake device is as follows.
As shown in fig. 1, the intake device includes: a
The
The electronic control device 20 uses an engine ECU. The ECU is an abbreviation of an electronic control unit, and is a microcomputer.
The outline of the fuel supply device 19a is as follows.
As shown in fig. 1, the fuel supply device 19a is of a common rail type, and includes: a plurality of
The
In the fuel supply device 19a, the electronic control device 20 calculates an engine load based on a deviation between a target rotation speed and an actual rotation speed of the engine, and the
As shown in fig. 1, the
As shown in fig. 1, the
The cylinder determination sensor 31 detects passage of a projection of a
The
The outline of the exhaust apparatus is as follows.
As shown in fig. 1, the exhaust apparatus includes: an
The outline of exhaust
Exhaust
The DPF is an abbreviation for diesel particulate filter, and is used to trap PM in engine exhaust. PM is an abbreviation for particulate matter. As shown in fig. 1, a wall-flow ceramic honeycomb in which a plurality of
DOC is an abbreviation for diesel oxidation catalyst, and oxidizes CO (carbon monoxide) and NO (nitrogen monoxide) in engine exhaust. In the DOC35, a flow-through ceramic honeycomb is used in which a plurality of
The exhaust
The regeneration device R of the DPF2 includes: a PM accumulation amount estimating device 4 for estimating the accumulation amount of PM accumulated in the DPF2, and an electronic control device 20, wherein the electronic control device 20 performs a regeneration process of the DPF2 based on the fact that the PM accumulation amount of the DPF2 reaches a predetermined regeneration necessary value. In the regeneration process of the DPF2, the exhaust gas temperature increasing device 19 increases the temperature of the
The PM accumulation amount estimation device 4 is constituted by the electronic control device 20, and estimates the accumulation amount of PM accumulated in the DPF2 based on the differential pressure detected by the
The exhaust gas temperature increasing device 19 includes: an
The
As shown in fig. 1, in the
When the exhaust gas temperature is low and the inlet-side exhaust gas temperature of the DOC35 does not reach the activation temperature of the DOC35, the
The start timing of the DPF regeneration process is as follows.
When the inlet-side exhaust gas temperature of the DOC35 reaches the activation temperature of the DOC35 at the time when the differential pressure detected by the
When the differential pressure detected by the
Instead of the post injection of the common rail type fuel supply device 19a, an exhaust pipe in which unburned fuel is injected into the
The engine has an ash accumulation alarm device for ash accumulated on the DPF.
The ash refers to ash of zinc compounds, calcium compounds, and the like.
The zinc compound is derived from an anti-wear agent and an antioxidant contained in the engine oil, and the calcium compound is derived from a cleaning agent and an acid neutralizing agent contained in the engine oil.
As shown in fig. 1, the engine has an ash deposition amount estimation device.
The ash deposition amount estimation device comprises: an exhaust
At the time of the regeneration process of the DPF2, the electronic control device 20 maintains the exhaust gas temperature within a predetermined range based on the detection of the exhaust
By maintaining the exhaust gas temperature within a predetermined range immediately before the end of regeneration, not only the pressure difference and the exhaust gas flow rate are less varied, but also PM that interferes with the estimation of the ash deposition amount is sufficiently burned, so that the ash deposition amount can be accurately estimated.
As shown in fig. 1, the storage device 6 and the
The storage device 6 may use a nonvolatile memory built in the electronic control device 20, and may use, for example, a flash memory, a P-ROM, an EP-ROM, or an E2P-ROM.
As shown in fig. 1, the engine includes an
Thus, the need for ash cleaning can be notified to the engine operator by an alarm.
The
The
The
As shown in fig. 1, the engine has an
The electronic control device 20 calculates the exhaust gas flow rate by the exhaust gas flow
A
In this case, the exhaust flow rate is calculated based on the intake air flow rate, the atmospheric pressure, the differential pressure, and the fuel supply amount, and therefore, the exhaust flow rate can be accurately estimated.
The exhaust flow rate is an exhaust volume flow rate per unit time, and is obtained by converting the intake flow rate measured by the
The volume flow rate of exhaust gas per unit time was set to V (m)3And/sec), the intake mass flow rate per unit time is G (G/sec), the DPF temperature is T (K), the atmospheric pressure is P0(kPa), the pressure difference of the DPF is Δ P (kPa), and the fuel supply amount per unit time is Q (cc/sec). The DPF temperature is estimated from the inlet exhaust temperature of
V(m3/sec)
=[G(g/sec)/28.8(g/mol)]
×22.4×10-3(m3/mol)
×[T(K)/273(K)]
×[P0(kPa)/(P0(kPa)+ΔP(kPa))]
+Q(cc/sec)/207.3(g/mol)
×0.84(g/cc)×6.75
×22.4×10-3(m3/mol)
×[P0(kPa)/(P0(kPa)+ΔP(kPa))]
The first term on the right of equation converts mass flow of the intake air to volumetric flow.
The second term on the right is the amount of increase from intake to exhaust gas caused by combustion of the injected fuel. In the second term, 0.84(g/cc) is a representative liquid density of light oil. 22.4X 10-3(m3/mol) is the volume of each 1mol of ideal gas at 0 degrees celsius at 1 atmosphere (atm). 6.75 is the rate of increase in the number of moles of the exhaust gas with respect to the fuel injection amount 1 (mol).
The estimation of the ash deposition amount can be based on the differential pressure Δ p (kpa) of the DPF2 divided by the exhaust gas flow rate V (m)3A/sec) obtained by the following steps3) When the differential pressure conversion value PC reaches a predetermined value (for example, 50kPa sec/m)3) When the estimated value of the ash deposition amount reaches the predetermined alarm necessary value, it is determined.
In this engine, instead of the above-described precise estimation of the exhaust gas flow rate, a simple estimation of the exhaust gas flow rate may be performed.
That is, the engine may be provided with an
In this case, the exhaust flow rate is calculated by considering the intake air flow rate as the exhaust flow rate, and therefore, the exhaust flow rate can be easily estimated.
The procedure of processing such as DPF regeneration and estimation of the amount of ash accumulation by the electronic control device will be described with reference to a flowchart.
As shown in fig. 2, in step S1, it is determined whether the estimated value of the PM accumulation amount of the DPF2 has reached a predetermined regeneration necessary value. The determination is repeated until affirmative, and if the determination is affirmative, the process proceeds to step S2.
In step S2, the DPF regeneration process is started, and the process proceeds to step S3. In the regeneration process of the DPF, when the inlet-side exhaust gas temperature of the DOC35 has not reached the activation temperature of the DOC35 and the
In step S3, the pressure difference and the exhaust gas flow rate on the exhaust gas inlet side and the exhaust gas outlet side of the DPF are stored, and the process proceeds to step S4.
In step S4, it is determined whether or not the regeneration end condition is satisfied. If the determination is positive, the process proceeds to step S5.
The regeneration end condition is that the integrated time for maintaining the DPF inlet exhaust gas temperature at a predetermined regeneration request temperature (for example, about 500 ℃) by post injection reaches a predetermined end set time.
In the regeneration of the DPF, when the exhaust gas temperature on the DPF outlet side reaches an abnormally high temperature (for example, about 700 ℃), the post injection is stopped in order to avoid thermal damage to the
In step S5, the DPF regeneration process is ended, and the process proceeds to step S6.
In step S6, the ash deposition amount is estimated from the differential pressure and the exhaust gas flow rate immediately before the end of regeneration, and the process proceeds to step S7. In the present embodiment, the period immediately before the end of the regeneration is a period between the end of the regeneration and a trace back time traced back by a predetermined time (10 minutes) from the end of the regeneration.
At step S7, it is determined whether the ash deposition amount has reached a predetermined alarm necessary value, and if the determination is affirmative, the routine proceeds to step S8.
In step S8, an alarm is issued, and the process returns to step S1.
When it is confirmed that ash from DPF2 is removed by cleaning and DPF2 is replaced, the alarm is released.
If the determination at step S4 is negative, the process proceeds to step S9.
In step S9, the regeneration process of the DPF2 is continued, and the process returns to step S3.
If the determination at step S7 is negative, the process returns to step S1 without issuing the alarm at step S8.