JPS597720A - Diesel particulate filter system - Google Patents

Abstract

PURPOSE:To both prevent melting damage of a trap and improve durability and reliability of a filter system, by providing a timer which automatically operates a recombustion device for a certain time after stopping of an engine. CONSTITUTION:If a key switch is turned off and an engine 1 is stopped, an engine stop detector circuit 16 generates an output signal, and an AND gate circuit 17 generates an operation signal in response to output signals from a particulate collective amount detector circuit 15 and the detector circuit 16, then a timer 18 operates a recombustion device 11 for a preset fixed time in response to said operation signal. An electric current from a power source 13 flows in a fuel pump 6, air pump 8 and a glow plug 10, and a mixture of fuel and air jetted from a fuel nozzle 7 and an air nozzle 9 is fired by the glow plug 10, then particulate collected in a trap 5 is burnt.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diesel particulate filter system that reduces particulates in exhaust gas discharged from an automobile diesel engine.

Conventionally, as a method for reducing particulate emissions from automotive diesel engines, a trap for collecting particulates is installed in the engine exhaust system, and the particulates in the trap are re-burned and incinerated using a light oil burner, electric heater, etc. .

In this method, particulates are re-burned when the amount of particulates collected in the trap reaches the permissible limit for deterioration of engine output and/or fuel efficiency, but the fuel consumption, excess air ratio, etc. are not properly controlled. If this happens, abnormal combustion occurs within the trap, causing problems such as melting and damage of the trap or failure of complete combustion of particulates.

As a countermeasure against this problem, it is desirable to reburn the particulates when the engine is stopped when the atmosphere inside the trap is in a stable state. As an example of such a conventional method, re-combustion of particulates is started in response to stopping the engine, and the temperature at the outlet of the particulate is detected by a temperature sensor provided at the outlet of the trap, and the above-mentioned restriction is determined from this detected temperature. There are some that determine the progress of combustion and terminate it. However, this method requires a temperature sensor, a judgment circuit, etc. to end the gate combustion, which is not only expensive, but also has limited durability because the temperature sensor is under high temperature conditions in the exhaust system. There is a problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a diesel particulate filter system that eliminates the above-mentioned conventional problems, can be manufactured at low cost, and has high durability and reliability.

In order to achieve this object, the present invention provides a reburning device that reburns particulates in the exhaust gas of a tasel engine that have been collected in a trap, and a particulate device that detects a state in which the trap is clogged with particulates. A tasel putty characterized in that it is equipped with a timer that automatically operates the reburning device for a certain period of time after the engine has stopped in response to both signals from the captured amount detection means and the engine stop detection means. This paper proposes a regulated filter system.

According to the above configuration of the present invention, since the reburning device is automatically operated for a certain period of time after the engine is stopped by the timer, the refrigeration device is automatically operated for a certain period of time after the engine is stopped. In addition to properly incinerating the ticulate and preventing the trap from melting, it also eliminates the need for expensive temperature sensors, reading circuits, etc., allowing the filter system to be manufactured at low cost, and improving its durability and reliability. It is.

Hereinafter, one embodiment of "Kienri" will be described in detail with reference to the accompanying drawings.

In the tasel baticulate filter system shown in FIG. 1, 1 is an automobile diesel engine, 2 is an air cleaner that purifies the air supplied to the engine l,
Reference numeral 3 denotes a fuel injection pump that outputs fuel from a fuel tank (not shown) to the engine.In the exhaust pipe 4 of the exhaust line of the engine 1, a trap 5 is arranged to collect particulates from the air. The trap 5 has a conventionally known structure made of a heat-resistant porous body. In the exhaust pipe 4 on the earth flow side of the trap 5, there is a fuel nozzle 7 that spouts out fuel from a fuel tank that is pumped by a fuel pump 6, and a fuel nozzle 7 that is arranged around the nozzle and that jets out air that is pumped by an air pump 8. An air nozzle 9 and a glow plug or spark plug 10 immediately downstream of both nozzles are provided for reburning of particulates! It constitutes the i-mount 7711.

A control device that controls the operation of the reburning device is disposed in the exhaust pipe 4 on the mold flow side of the trap 5, and includes a pressure sensor 12 that detects exhaust pressure, and an exhaust pressure signal and a signal from the pressure sensor 12. It has a controller 14 that receives engine signals representing the operating state of the diesel engine 1 and applies current from a power source 13 to the fuel pump 6, air pump 8, and glow plug 10 based on these signals. Controller 1
4, as shown in FIG. 2, it is determined from the exhaust pressure signal from the pressure sensor 12 and the engine signal that the amount of particulates trapped in the trap 5 is clogged to the allowable limit for deterioration of engine output and/or fuel consumption. a particulate trap detection circuit 15 that detects and issues an output signal, an engine stop detection circuit 16 that detects that the engine 1 has stopped due to the key switch being turned off and issues an output signal, and a 'particulate capture amount detection circuit'. 15 and the engine stop detection circuit 16, which outputs an activation signal only when receiving the Ryokawa power signal from the AND gate circuit 16, and in response to the activation signal from the AND gate circuit 17, a current is supplied to the reburning device 11 for a certain period of time. It has a timer 18 which is operative to supply. The time required to completely burn particulates is inevitably determined once the size of the trap 5 is determined, so the operating time of the timer 18 is set in advance to, for example, 2 to 3 minutes, depending on the size of the trap 5. It is set. Further, the output signal from the particulate collection amount detection circuit 15 is input to an alarm 19 such as a tank or a buzzer provided in the driver's cabin of the automobile.

During operation of an automobile diesel engine 1, if the amount of particulates collected in the trap 5 is below the allowable limit for deterioration of engine output and/or fuel efficiency, the controller≠14 causes the fuel pump 6, the air pump 8, and the glow plug to 10 is not supplied with current from the power source 13, and the ladle combustion device 11 is in an inactive state.

When the amount of particulates collected in the trap 5 exceeds the above-mentioned allowable limit while the engine 1 is running, the particulates collected amount detection circuit 15 issues an output signal, but at this point, since the engine 1 is running, The engine stop detection circuit 16 does not provide an output signal, so the afterburner 11 remains inactive. In addition, the alarm 19 is activated by the output signal from the particulate collection amount detection circuit 15, and the alarm 19 is activated.
Reburning will automatically start the next time the engine is stopped. Therefore, the driver is advised not to restart the engine for several minutes until the reburning is complete.

When the engine 1 is stopped by turning off the key switch for parking, etc., the engine stop detection circuit 16 issues an output signal, and the AND gate circuit 17 responds to the output signals from the rain detection circuits 15 and 16 to issue an activation signal. The timer 18 operates the reburning device 11 for a predetermined period of time in response to this activation signal. As a result, current from the power source 13 flows to the fuel pump 6, air pump 8, and glow plug IO.

The mixture of fuel and air ejected from the fuel nozzle 7 and the air nozzle 9 is ignited by the glow plug IO to burn the particulates collected in the trap 5.
t'6 Reject.

As described above, the tasel particulate filter system according to the present invention operates for a preset time according to the size of the trap 5 after the engine is stopped by the timer 18.
The reburning device 11 is configured to be automatically activated. As a result, since particulates consisting of solid carbon and hydrocarbons generally burn at temperatures of about 500°C, it is possible to re-burn the particulates when the engine is stopped and the atmosphere inside the trap 5 is stable.
It can be stably burned between about 806C and about 1000C, and therefore the trap 5, which can melt at about 2600C, can be prevented from being melted away. In addition, since the timer 18 is used to terminate particulate re-burning, the filter system has a simpler structure compared to conventional systems that use expensive temperature sensors and judgment circuits to terminate re-burning. It can be manufactured at a low cost, and since there is no need for a temperature sensor placed under the temperature condition of the cylinder of the exhaust system, it has excellent durability and reliability.

Furthermore, if the engine is restarted in the middle of re-combustion, most of the easily flammable hydrocarbons that are particulates will be burned, leaving only solid carbon, which will be used for the next re-combustion. However, the alarm 19 notifies the driver that ``the engine must not be restarted for several minutes until the reburning is complete.''
This is extremely beneficial as it can prevent the driver's erroneous operations before the completion of reburning as much as possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a diesel particulate filter system according to the present invention, and FIG. 2 is a block circuit diagram of the controller of FIG. 1. 1. Diesel engine, 4. Exhaust 'A'fl, 5.
・Trap, 6...Fuel pump, 8...Air pump, 1
0... Glow plug, 11... Reburning device, 12... Pressure sensor, 14... Controller, 15... Particulate collection amount detection circuit, 16... Engine stop detection N path, 17... AND gate circuit , 1B... timer.

Claims (1)

[Scope of Claims] F [means for re-burning particulates in the exhaust gas of a diesel engine that have been collected in the exhaust trap, engine stop detection means for detecting that the engine has stopped, and the amount of particulates collected. A diesel particulate filter system characterized by comprising a timer that automatically operates the reburning device for a certain period of time after the engine is stopped in response to both signals from the detection means and the engine stop detection means.