JPH0355773Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] This invention relates to an exhaust gas purification device with a catalyst that purifies harmful components in exhaust gas discharged from diesel engines and gasoline engines.

[Technical background of the invention and its problems] There are various harmful components in the exhaust gas of diesel engines and gasoline engines, but three of them, C0, HC, and NO _x, are subject to regulation. . Therefore, conventionally, an exhaust gas purification device is installed in the middle of an exhaust pipe that discharges exhaust gas from an engine to absorb and purify the harmful components.

There are various types of exhaust gas purification devices, and recently, a ceramic filter equipped with a catalyst is known. A ceramic filter with a catalyst is installed inside the case body, and when exhaust gas passes through this filter, harmful components are absorbed. However, when the vehicle is running at low speed, the temperature of the exhaust gas is low, and there is a disadvantage that particulates containing soot in the exhaust gas cannot be completely combusted. Therefore, there is a disadvantage that the ceramic filter becomes clogged with the particulate and cannot absorb and purify harmful components in the exhaust gas.

[Purpose of the invention] This invention was made by focusing on the above-mentioned circumstances, and its purpose is to reduce the amount of soot contained in the exhaust gas even when the vehicle is running at low speed and the temperature of the exhaust gas is low. To provide an exhaust gas purifying device capable of completely burning particulate matter, preventing a ceramic filter from being clogged with the particulate matter, and fully exhibiting an exhaust gas purifying action.

[Summary of the invention] In order to achieve the above-mentioned purpose, this invention uses a catalyst-equipped catalyst to purify harmful components in the exhaust gas in an exhaust gas purification device installed in the middle of the exhaust pipe that discharges exhaust gas from the engine. An electric heater for heating the exhaust gas flowing inside the case body is provided on the upstream side and the downstream side in the case body having the purifying member, and a temperature detection means for detecting the temperature of the exhaust gas flowing inside the case body, and an exhaust gas. When the gas temperature is below the set value, the upstream electric heater is energized to heat the exhaust gas, and if the heating is insufficient,
The present invention is characterized in that it includes a control device that energizes the electric heater on the downstream side and heats the exhaust gas by both electric heaters.

[Embodiment of the invention] An embodiment of the invention will be described below based on the drawings.

In the figure, reference numeral 1 denotes an exhaust pipe that exhausts exhaust gas discharged from a diesel engine and a gasoline engine. A case body 2 of an exhaust gas purification device is provided in the middle of the exhaust pipe 1. Inside the case body 2 are built-in purifying members 3a and 3b made of ceramic filters with catalysts. Further, electric heaters 4 are provided on the upstream side of the purifying member 3a and between the purifying members 3a and 3b.
a and 4b are provided. The electric heaters 4a, 4b are energized to heat the exhaust gas when the purification members 3a, 3b are clogged or when the temperature of the exhaust gas is lower than a set value. That is, 5 is a pressure sensor that detects the pressure between point a on the upstream side and point b on the downstream side of the case body 2, and when the pressure difference is more than a set value, the purifying member 3
A and 3b are determined to be clogged and a signal is input to the control device 6. Further, 7 is a temperature sensor that detects the temperature at point a on the upstream side of the case body 2, that is, the temperature of the exhaust gas. This temperature sensor 7 is configured to input a signal to the control device 6 when the temperature of the exhaust gas is below a set value.
Then, the control device 6 controls the electric heater 4 based on the input signals from the pressure sensor 5 and the temperature sensor 7.
a and 4b are turned on and off.

Therefore, when the vehicle is running at high speed, the temperature of the exhaust gas is high and the particulate is completely combusted and no clogging occurs, so the purifying members 3a and 3b can purify the harmful components of the exhaust gas. However, when the vehicle is running at low speed, the temperature of the exhaust gas is low and the particulate containing soot cannot be combusted. Therefore, the purifying members 3a and 3b may become clogged, but the pressure difference between the upstream point a and the downstream point b in the case body 2 is constantly detected by the pressure sensor 5. The temperature of the exhaust gas is detected by a temperature sensor 7. Therefore, when the pressure difference exceeds the set value or when the temperature falls below the set value, the electric heaters 4a and 4b are energized. In this case, first, the electric heater 4a on the upstream side is energized to heat the exhaust gas, and combustion is started from the particulate in the purification member 3a on the upstream side. When it becomes difficult to completely burn the particulate matter in the purification member 3b on the downstream side using only the electric heater 4a, electricity is supplied to the electric heater 4b on the downstream side in addition to the electric heater 4a on the upstream side, and Heating the exhaust gas. Therefore, the exhaust gas is completely combusted in a short time by the electric heaters 4a and 4b until the particulate hydrate reaches the purification member 3b on the downstream side. Therefore, even if the temperature of the exhaust gas decreases during low-speed running, the particulate is burned, the purifying members 3a and 3b are unclogged, and harmful components in the exhaust gas are absorbed.

[Effects of the invention] As explained above, according to this invention, the temperature of exhaust gas is detected by a temperature sensor, and when the temperature falls below a set value, electricity is activated in stages from the upstream side to the downstream side. Since the heater is energized and the exhaust gas is heated by the electric heater to a temperature at which the particulate can be combusted, even if the temperature of the exhaust gas drops during low-speed driving, the particulate can be heated downstream of the purification member in a short time. Since it is completely combusted and prevents clogging, it has the effect of absorbing and purifying harmful components in the exhaust gas that passes through the purifying member.

[Brief explanation of the drawing]

The drawing is a schematic diagram showing an embodiment of this invention. 1... Exhaust pipe, 2... Case body, 3a, 3b
...Purification member, 4a, 4b...Electric heater, 7...
...Temperature sensor.

Claims (1)

[Scope of utility model registration request] In an exhaust gas purification device installed in the middle of an exhaust pipe that discharges exhaust gas from an engine, the case body has a purification member with a catalyst that purifies harmful components in the exhaust gas on the upstream and downstream sides of the case body. An electric heater is provided to heat the exhaust gas flowing inside the case body, and a temperature detection means is provided to detect the temperature of the exhaust gas flowing inside the case body, and when the exhaust gas temperature is below a set value, the electric heater on the upstream side is energized. What is claimed is: 1. An exhaust gas purification device comprising: a control device which heats the exhaust gas by heating the exhaust gas, and further energizes a downstream electric heater to heat the exhaust gas by both electric heaters when the heating is insufficient.