JPH0596420U - Exhaust gas purification device for diesel engine - Google Patents

Abstract

(57) [Summary] [Object] The present invention aims to provide an exhaust emission control device for a diesel engine that regulates the maximum temperature during regeneration of a trap filter, improves reburning efficiency, and prevents melting damage of a filter element. I am trying. In a diesel engine having a trap filter and a bypass passage bypassing the filter in an exhaust passage, a moving average process is performed on data of engine rotation, exhaust temperature, and exhaust pressure to determine a regeneration time, and the trap inlet is based on the data. A control device is provided to control the gas amount.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention provides a trap filter in the exhaust passage of an engine, a bypass passage bypassing the trap filter, an opening / closing valve for opening and closing each passage, and a heater in front of the trap filter, an exhaust temperature sensor, an exhaust pressure The present invention relates to an exhaust emission control device for a diesel engine, which has a control device that controls regeneration of the trap filter based on signals from a sensor and an engine rotation sensor.

[0002]

[Prior Art]

 There is known a technique of fixing the opening / closing valve at the entrance of the trap filter at the time of regeneration of the trap filter and controlling the opening / closing valve of the bypass passage by the differential pressure across the trap filter to control the amount of exhaust gas flowing to the trap filter (for example, , Japanese Unexamined Patent Publication No. 1-155017).

[0003]

[Problems to be solved by the device]

 However, since the above technology detects the differential pressure before and after the trap filter and controls the exhaust gas flow rate, it cannot respond to changes in the gas flow rate during sudden acceleration / deceleration, and the exhaust gas flow rate flowing to the trap filter cannot be adjusted. There is a problem in that the filter suddenly changes and the maximum temperature during trap regeneration cannot be suppressed and the filter is damaged.

[0004] Also, Japanese Utility Model Laid-Open No. 3-118210 is disclosed by the present applicant, but it is insufficient because the above-mentioned differential pressure is detected and controlled.

Therefore, an object of the present invention is to provide an exhaust emission control device for a diesel engine, which suppresses the maximum temperature during regeneration of the trap filter, improves reburning efficiency, and prevents melting damage of the filter element.

[0006]

According to the present invention, a trap filter is provided in an exhaust passage of an engine, a bypass passage for bypassing the trap filter, an opening / closing valve for opening / closing each passage, and a front surface of the trap filter are provided. In a diesel engine exhaust gas purification device having a heater, and having a control device that controls regeneration of the trap filter based on signals from an exhaust gas temperature sensor, an exhaust gas pressure sensor, and an engine speed sensor, engine rotation and exhaust gas temperature A control device that determines the regeneration timing based on data obtained by moving average processing the data of exhaust pressure and controls the on-off valve based on the data to adjust the amount of exhaust gas flowing into the trap filter to control regeneration of the trap filter. Is provided.

[0007]

[Action]

 In the exhaust gas purification device for a diesel engine configured as described above, the data from the engine speed sensor, exhaust temperature sensor and exhaust pressure sensor are subjected to moving average processing by the control device to determine the regeneration time, and the trap entrance side The on-off valve is closed to raise the temperature of the front heater to a constant temperature, and the trap inlet gas flow rate is controlled to be constant based on the data obtained by moving average processing the engine rotation, exhaust temperature and exhaust pressure data. The amount of gas entering the trap does not change suddenly because it is based on the moving average processed data. If there is a sudden change in the gas amount or temperature change in the filter, the open / close valve on the trap side is closed and the bypass side is opened so that the entire exhaust gas flows to the bypass side. Melting damage is prevented.

[0008]

【Example】

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, a trap filter 1 is attached to an exhaust pipe 2 attached to an engine 20, an inlet valve 7 which is an opening / closing valve is provided at an inlet of the trap filter 1, and a front heater is provided downstream thereof. 4 is provided and is connected to the power source via an electromagnetic switch 5 connected to the controller 14. A bypass valve 9 which is an opening / closing valve is attached to the inlet of the bypass pipe 3 that bypasses the trap filter. An exhaust temperature sensor 15 that detects the exhaust temperature Te and an exhaust pressure sensor 16 that detects the exhaust pressure Pe are provided upstream of the inlet valve 7, and are connected to the controller 14 by signal circuits. Further, the inlet control valve 10 and the bypass valve control valve 11 for controlling the inlet valve 7 and the bypass valve 9, respectively, are connected to the vacuum pump 12 and also connected to the drive unit for driving the inlet valve 7 and the bypass valve 9. The control valves 10 and 11 are connected to the controller 14.

A bypass pressure sensor 17 for detecting the bypass pressure P2 is provided on the downstream side of the bypass valve 9, and an inlet pressure sensor 18 for detecting the trap inlet pressure is provided on the downstream side of the inlet valve 7, and is connected to the controller 14. Has been done. Further, a front surface temperature sensor 6 for detecting a front surface temperature Tf is provided on the front surface of the trap filter 1, and an internal temperature sensor 8 for detecting an internal temperature Ti is provided inside the filter 1, and each of them is provided with a controller 14 It is connected to the.

An outlet pressure sensor 19 for detecting the outlet pressure P3 is provided at the outlet of the filter, and an engine rotation sensor 13 for detecting the engine rotation Ne is provided in the engine.

The operation will be described below with reference to FIG.

During operation, the engine speed Ne, exhaust pressure (exhaust pressure) Pe, exhaust temperature (exhaust temperature) Te, inlet pressure (inlet pressure) P1, bypass pressure (bypass pressure) P2, outlet pressure (outlet pressure) P3 is input (step S1). Then, in step S2, Y1 (representing the moving average of the gas amount) and X1 (representing the moving average of the differential pressure of the filter) are calculated, and referring also to FIG. 3, Y1 / X1 is calculated from the slope indicated by A. It is judged whether or not it is larger (step S3). If NO, the process returns. If YES, the inlet valve 7 is fully closed, the bypass valve 9 is fully opened, and the front heater 4 is turned ON (step S4), and the regeneration timing is set. Judge.

Next, with reference to FIG. 5, it is determined whether the filter front surface temperature Tf is higher than a predetermined temperature TB (eg, 700 ° C.) (step S5). If NO, the process returns, and if YES, Y2 and X2 are calculated (step S6), and the reproduction preparation ends.

Referring also to FIG. 4, the opening degree of the inlet valve 7 is adjusted (step S7), and it is determined whether Y2 / X2 is larger than the inclination indicated by B (step S8). . If YES, the opening of the bypass valve is adjusted (step S9). If NO, it is determined whether the inlet valve 7 is fully closed (step S13). If NO, the process returns to step S7. If YES , And proceeds to step S9.

Further, it is determined again whether Y2 / X2 is larger than the slope B (step S10). If NO, the process returns to step S9, and if YES, it is determined whether or not a fixed time (for example, 20 minutes) has elapsed since the heater was turned on (step S11). If NO, the process returns and if YES, the inlet valve 7 is fully opened, the bypass valve 9 is fully closed, and the heater 4 is turned off (step S12) to terminate the trap filter regeneration control.

Next, as abnormal processing, referring to FIGS. 5 and 6, interrupt processing (IRQ; see FIG. 7) is performed when the temperature change (ΔT / Δt) inside the trap becomes large. In FIG. 7, the engine speed Ne, the exhaust pressure Pe, and the exhaust temperature Te are input (step S15), the gas amount is calculated, and it is determined whether or not it is between the constants K1 and K2 (step S16). If NO, the process returns, and if YES, it is determined whether the temperature change in the trap filter is normal (step S17). If YES, the process returns. If NO, the inlet valve 7 is fully closed and the bypass valve is fully opened. Then, the heater 4 is turned off to prevent the trap filter from melting.

[0018]

[Effect of the device]

 Since the present invention is configured as described above, it is possible to control the inlet gas amount of the trap filter with high accuracy to be constant, and the regeneration efficiency is high. In addition, since the on-off valves at two locations are controlled, exhaust pressure does not rise easily, fuel consumption can be prevented from deteriorating, and the maximum temperature of the filter can be suppressed even during rapid acceleration / deceleration, thus preventing filter meltdown. Therefore, the filter can be used efficiently for a long period of time.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart of the control of FIG.

FIG. 3 is a diagram showing a relationship between a differential pressure for determining a regeneration time and a gas amount.

FIG. 4 is a diagram showing a relationship between a differential pressure for adjusting a valve opening and a gas amount.

FIG. 5 is a regeneration temperature chart.

FIG. 6 is a diagram showing a relationship among gas amount, filter temperature, and regeneration efficiency.

FIG. 7 is a flowchart of interrupt processing.

[Explanation of symbols]

 1 ... Trap filter 3 ... Bypass pipe 4 ... Front heater 5 ... Electromagnetic switch 6 ... Front temperature sensor 7 ... Inlet valve 8 ... Internal temperature sensor 9 ... Bypass valve 10 ... Trap inlet control valve 11 ... Bypass inlet control valve 13 ... Engine rotation Sensor 14 Controller 15 Exhaust temperature sensor 16 ... Exhaust pressure sensor 17 ... Bypass pressure sensor 18 ... Inlet pressure sensor 19 ... Outlet pressure sensor

Claims (1)

[Scope of utility model registration request] 1. A trap filter is provided in an exhaust passage of an engine, a bypass passage bypassing the trap filter, an opening / closing valve for opening and closing each passage, and a heater are provided in front of the trap filter, and an exhaust temperature sensor and an exhaust pressure are provided. In an exhaust emission control device for a diesel engine having a control device for controlling the regeneration of the trap filter based on the signals from the sensor and the engine rotation sensor, the data of the engine rotation, the exhaust temperature and the exhaust pressure are regenerated with the data obtained by moving average processing. Exhaust gas purification of a diesel engine, which is provided with a control device that determines the timing, controls the on-off valve based on the above data, adjusts the amount of exhaust gas flowing into the trap filter, and controls the regeneration of the trap filter. apparatus.