JPH0417794Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to an exhaust purification device for a diesel engine that can prevent overheating of a particulate trap installed in an exhaust passage.

[Conventional technology]

In order to prevent dust in the exhaust from being released into the atmosphere, a monolith-type particulate trapper is installed in the exhaust passage of a diesel engine. There was no way to prevent Toratsupa from overheating.

[Problem that the invention attempts to solve]

Therefore, even if the soot becomes clogged with soot and re-combusts, causing the temperature of the particulate trap to rise excessively, this cannot be prevented and the particulate trap is damaged. There is a risk of

The purpose of this invention is to provide an exhaust purification device for a diesel engine that can prevent overheating of a particulate trapper due to soot re-combustion.

[Means for solving problems]

Therefore, the exhaust purification device for diesel engines according to this invention includes a particulate trapper disposed in the exhaust passage, an optical sensor that detects combustion light in the particulate trapper, and an output of this optical sensor. The degree of combustion in the particulate trap is detected, and if the combustion is severe, the fuel injection amount is reduced via the electronic governor of the injection pump, and the fuel injection amount is reduced via the electronic timer of the injection pump. and fuel injection control means for advancing the injection timing.

[Effect]

When reburning of soot occurs in the particulate trapper and the combustion light becomes stronger, the fuel injection control means reduces the fuel injection amount and advances the fuel injection timing. The reduction in the amount of fuel injection reduces the amount of soot generated, and the advancement of the fuel injection timing causes combustion in the combustion chamber to end earlier, thereby reducing the amount of soot discharged into the exhaust passage. This suppresses the re-burning of soot in the particulate trapper and suppresses the temperature rise of the particulate trapper.

[Effect of idea]

As a result of preventing the particulate trapper from overheating in this way, it is possible to prevent damage to the particulate trapper due to overheating.

〔Example〕

This invention will be explained below with reference to the embodiments shown in the drawings.

The diesel engine 1 receives fuel from an injection pump 2, and the injection pump 2 is connected to an electronic governor 3 that controls the fuel injection amount.
and a well-known electronic timer 4 that controls the fuel injection timing by changing the oil pressure acting on the timer piston. The exhaust side of the diesel engine 1 is connected to an exhaust pipe 6 via an exhaust branch pipe 5. A monolith type particulate trapper 7 is disposed in the exhaust pipe 6 to capture dust in the exhaust gas and prevent it from being released into the atmosphere. The optical sensor 8 is
It is disposed at the downstream end of the particulate trapper 7, includes an optical fiber, etc., and detects combustion light within the particulate trapper 7. computer 9
receives an input signal from the optical sensor 8 and controls the electronic governor 3 and the electronic timer 4.

The operation of the embodiment will be explained. When the particulate trapper 7 becomes clogged with soot and the combustion light in the particulate trapper 7 becomes stronger due to re-burning of the soot, the computer 9 reduces the fuel injection amount via the electronic governor 3. At the same time, the fuel injection timing is advanced via the electronic timer 4. Reducing the amount of fuel injection reduces the amount of soot generated, and advancing the timing of fuel injection ends combustion in the combustion chamber of the diesel engine 1 earlier, reducing the amount of soot discharged into the exhaust passage, thus reducing particulate matter. The amount of soot sent to the trapper 7 is reduced, and re-burning of soot in the particulate trapper 7 is suppressed. This will result in a
overheating and damage caused by it can be avoided.

In other cases, the combustion light in the particulate trapper 7 is weak, so that the computer 9 does not take the above-mentioned measures to prevent the particulate trapper 7 from overheating.

[Brief explanation of drawings]

The drawing is a block diagram of one embodiment of this invention. DESCRIPTION OF SYMBOLS 1... Diesel engine, 3... Electronic governor, 4... Electronic timer, 6... Exhaust pipe, 7... Particulate trapper, 8... Optical sensor, 9
...computer.

Claims (1)

[Claims for Utility Model Registration] (1) A particulate trapper disposed in the exhaust passage, an optical sensor for detecting combustion light in the particulate trapper, and a An exhaust gas purification device for a diesel engine, comprising a fuel injection control means that detects the degree of combustion in a particulate trapper and, when combustion is intense, reduces the fuel injection amount and advances the fuel injection timing. (2) The fuel injection control means reduces the fuel injection amount via an electronic governor of the injection pump and advances the fuel injection timing via an electronic timer of the injection pump. The exhaust purification device for a diesel engine according to item 1.