JPH0622110Y2 - Particulate filter regeneration device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a reproducing apparatus for a particulate filter.

[Prior Art] In order to reduce particulate matter (particulate) emitted from a diesel engine, a particulate filter that collects particulate matter is known,
Further, in order to prevent the filter from being clogged by the collected particulates, there are known various regenerators that are provided with a heating means for exhaust gas to reburn the particulates to regenerate the filter (for example, a special method). Kaisho 62-255
No. 511, Japanese Utility Model Application No. 60-18501
No. 6, etc.).

In the conventional regenerator, the length of the filter element is generally long, and it is difficult to control the heating of a heating means such as an electric heater. Therefore, the combustion gas of the particulates easily escapes to the downstream portion of the element where the air resistance is small, that is, the combustion propagating property is poor, and a non-regenerated area A shown by hatching appears at the rear portion of the filter element 13 as shown in FIG. Then, the insufficiently burned particulates attached to the central portion surrounded by the circle in the region A are rapidly burned to generate the erosion region B, and the regeneration efficiency is lowered. Reference numeral 7 in the figure is an electric heater.

In general, various kinds of particulate filter regenerators are known. For example, Japanese Utility Model Laid-Open No. 60-14220 discloses a technique of controlling an ignition current depending on an operating state, but the prevention of melting damage is not sufficient. . Actual Kaisho 60-54
No. 14 and No. 59-24911, 2
A split filter is disclosed. However,
In all of these known techniques, measures against melting damage are insufficient.

[Problem to be solved] Therefore, an object of the present invention is to provide a regenerating apparatus for a particulate filter, which has high regeneration efficiency and can prevent melting damage.

[Means for Solving the Problems] According to the present invention, a particulate filter regeneration in which a filter element housed in a filter case is divided into an upstream side and a downstream side and an intermediate air chamber is defined between them is regenerated. In the apparatus, heating means that is intermittently operated is provided on the upstream side of the upstream element, and the heating means is composed of an electric heater and is connected to a control unit, and the control unit detects clogging provided near the heater. A back pressure sensor, a temperature sensor for detecting the temperature near the downstream side of the downstream element, and a rotation speed sensor and a load sensor for detecting the engine operating state are connected, and the control unit receives signals from the back pressure sensor. Based on the above, when the back pressure is large, the ON time of the heater is reduced and the OFF time is increased as the engine load increases. It has a control function.

[Explanation of Action and Effect] Therefore, the control unit judges whether or not the element is clogged with the signal from the back pressure sensor and the regeneration is necessary, and if necessary, the electric heater is intermittently operated. The time is determined according to the load from the rotation sensor and the load sensor. When the melting temperature is reached by the signal from the temperature sensor, the rotation speed and the load are input to determine whether or not the regeneration is completed. At that time, the upstream element is relatively easily clogged, but even if uneven flow occurs due to clogging, the flow can be made uniform in the intermediate air chamber, combustion propagation can be improved, and regeneration efficiency can be improved. To do.

In addition, the on / off of the heater is controlled so that it is easy to control and the proper control can be performed according to the number of rotations and the load. If the electric heater continues to heat during the combustion work for regeneration, the heater will be turned off. After that, the melting temperature is easily exceeded, but melting loss can be prevented by repeating ON and OFF intermittently. Further, since the heating time of the electric heater is changed according to the load, the melting time can be reliably prevented by shortening the heating time when the exhaust gas temperature is high and the load is high.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, an upstream element 3 and a downstream element 4 each having a length obtained by dividing a conventional filter element into two are housed in a case 2 of a particulate filter 1 via a spacer 5 with a space therebetween. The hollow air chamber 6 is defined by these.

An electric heater 7 as a heating means is provided near the upstream side of the upstream element 3, and the heater 7 is connected to the control unit 15. That unit 15
The exhaust pressure sensor 8 provided near the downstream side of the heater 7.
The temperature sensor 9 provided in the vicinity of the downstream side of the downstream element 4 is connected to the rotation speed sensor 10 and the load sensor 11 provided in the engine (not shown).

At the time of control, as shown in FIG. 2, the control unit 15 inputs the engine speed and load based on signals from the speed sensor 10 and the load sensor 11 (step S
1) Based on the signal from the exhaust pressure sensor 8, it is determined whether the exhaust pressure is higher than the standard back pressure when the elements 3 and 4 are not clogged and regeneration is necessary (step S2). . If NO, the control is terminated, and if YES, a control signal is output and the electric heater 7 is intermittently turned on (step S3). As shown in FIG. 3, the intermittent control of the heater 7 depends on the load and is ON for, for example, 5 seconds when the load is high.
Then, it is turned off for 5 seconds (characteristic I), and for a low load, for example, 6 seconds O
Since the exhaust gas temperature is higher and the flow velocity is higher as the load is higher, the control is performed so that the ON time is decreased and the OFF time is increased so as to turn off for 4 seconds (characteristic II). Next, based on the signal from the temperature sensor 9, it is determined whether the regeneration temperature t is lower than the melting temperature t1 of the element (for example, 1000 ° C.) (step S4). If YES, for example, characteristics
As in II, the ON time of the heater 7 is increased, the OFF time is reduced, and regeneration is promoted (step S5).
Returning to No. 4, in the case of NO, that is, when the regeneration temperature t reaches the melting temperature t1, the engine speed and load are input (step S6), and the exhaust pressure is set to the standard value based on the signal from the exhaust pressure sensor 8. It is determined whether or not the pressure is reached and the reproduction is completed (step S7). If NO, the process returns to step S4. If YES, a control signal is output and the operation of the heater 7 is turned off (step S8), and the control ends.

[Effects of the Invention] As described above, the present invention has the following excellent effects.

(I) Since the electric heater is intermittently turned on and off, abrupt combustion of the particulates can be suppressed, and melting damage of the wake side element can be prevented.

(ii) Since the time for which the electric heater is turned on and off differs depending on the load, temperature control is preferably performed. The electric heater can be efficiently energized with no waste, and the particulate melt damage can be prevented.

(iii) Therefore, the regeneration efficiency can be improved without causing melting loss.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention, FIG. 2 is a control flowchart diagram, FIG. 3 is an intermittent operation control characteristic diagram of a heater, and FIG. 4 is a side sectional view showing a conventional device. 2 ... Case, 3 ... Upstream element, 4 ... Downstream element, 6 ... Intermediate air chamber, 7 ... Electric heater

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Keiichi Niimura, 1-chome, Ichichome, Ageo-shi, Saitama, Nissan Diesel Industry Co., Ltd. (72) Shuichi Nakamura 1-chome, 1-chome, Ageo, Saitama Prefecture Co., Ltd. (72) Inventor, Kitamura Sentence, Io-chome, 1-chome, Ageo City, Saitama Nissan Diesel Industry Co., Ltd. (56) References , U)

Claims (1)

[Scope of utility model registration request] 1. A regenerating apparatus for a particulate filter, wherein a filter element housed in a filter case is divided into an upstream side and a downstream side, and an intermediate air chamber is defined between the two sides. A heating means for intermittent operation is provided on the side, and the heating means is composed of an electric heater and is connected to a control unit, and the control unit is provided with a back pressure sensor for detecting clogging provided in the vicinity of the heater and a downstream element. A temperature sensor that detects the temperature near the downstream side and a rotation speed sensor and a load sensor that detect the engine operating state are connected, and when the control unit has a large back pressure based on the signal from the back pressure sensor. The higher the engine load, the more O
A particulate filter reproducing apparatus having a function of performing intermittent control so as to reduce N time and increase OFF time.