JPH0436249B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an exhaust purification device for a diesel engine, and more specifically, it physically removes carbon particles and similar particulate matter (hereinafter referred to as particulate matter) contained in exhaust gas. The present invention relates to a filter regeneration device in an exhaust gas purification apparatus suitable for collecting particulate matter on a suitable collection material such as a filter element, periodically incinerating the collected particulate, and regenerating the collection material.

Prior Art Most of the particulate matter contained in the exhaust gas of diesel engines is flammable, such as carbon particles, and such flammable particulate matter is collected by a filter, and the collected particulate matter is incinerated. Various diesel engine particulate traps for regenerating filters are known. An electric heater is generally used as a means for burning the collected particulate and regenerating the filter. That is, an electric heater is attached over the entire front surface of the filter, and the heater burns the particulate matter adhering to the surface of the filter, and uses it as a heat source to self-combust the downstream particulate matter.
However, in such a system, the power consumption of the heater during regeneration is not small, and it is desirable to keep the power consumption as low as possible, especially when an on-board battery is used as a power source, as in the case of an automobile. To achieve this, it is possible to place the electric heater and the filter as close as possible, but in doing so, there are various difficulties in assembling the heater or processing accuracy, and it is also difficult to place the heater close to the filter. There is also the problem of damaging the heater if it is placed too close.

There is also a method in which the filter is heated by engine exhaust gas in order to reduce power consumption, but this method generally has the problem of complicating the system.

Purpose of the Invention The present invention was made in order to solve the problems in the conventional device as described above, and its purpose is to improve the ignition ability of the electric heater in an electric ignition type filter regeneration device. The power consumption is minimized, and there is no need for accuracy control when assembling the heater, and there is no damage to the heater.
An object of the present invention is to provide a filter regeneration device in an exhaust purification device for a diesel engine.

Structure of the Invention In order to achieve the above object, the present invention is characterized in that two types of heaters, a heater for preheating the filter and a heater for igniting particulate matter, are provided on the front surface of the filter.

Embodiments Examples of the present invention will be described below with reference to the drawings.

FIG. 1 is a system diagram of the entire diesel engine to which the filter regeneration device of the present invention is applied. In the figure, 1 is the diesel engine main body, 2 is the intake passage, and 3 is the exhaust passage. Reference numeral 4 designates a particulate trap provided in the exhaust passage 3, in which a suitable filter is housed, and an electric heater is attached to the front surface of the filter, the details of which will be described later. 5 is a bypass path provided in the exhaust path 3;
Its opening and closing is controlled by a bypass valve 6. 7
is an actuator for driving the bypass valve 6, and operates to open the bypass valve 6 by introducing negative pressure from the vacuum pump 8 into the diaphragm chamber of the actuator 7.

Numerals 9 and 10 are negative pressure switching valves that switch between introducing negative pressure and introducing atmospheric air into the actuator 7, and their operation is controlled by a computer 11. 12 is an electric heater relay whose operation is controlled by the computer 11;

13 is a fuel injection pump, 14 is an intake throttle valve, 1
5 is an actuator for driving an intake throttle valve, 16 is a water temperature sensor, 17 is a load sensor, 18 is a rotation speed sensor, 19 and 20 are negative pressure switching valves, and 21 is an intake negative pressure sensor.

As shown in FIGS. 2 and 3, the arrangement of the electric heaters in the embodiment of the filter regeneration device according to the present invention is divided into two types: a filter preheating heater 31 and a particulate ignition heater 32. The preheating heater 31 is a filter 36
The heater 32 is attached to the electric heater support flange 30 and the electric heater support stay 35 so as to cover the front peripheral part of the filter 36, and the particulate ignition heater 32 is attached to the electric heater support stay 35 so as to cover the central part of the front surface of the filter 36. be.

33 is an electric heater power supply terminal, and 34 is a power supply connector.

The operation of this embodiment having the above configuration is as follows.

In FIG. 1, the detection result of the engine rotation speed is sent to the computer 1 by the rotation speed sensor 18.
1, the number of rotations is accumulated, and when the preset cumulative number of rotations is reached, the computer 1
1 determines that it is time to regenerate the filter 36 and starts energizing the electric heater,
Open bypass valve 6.

To energize the electric heater, first, the electric heater relay 12 is activated by a command from the computer 11 to energize only the filter preheating heater 31 to raise the temperature of the front peripheral portion of the filter 36 to about 300 to 400°C. The power required at this time is 500 W in total for the four preheating heaters 31 shown in FIG.

After a certain period of time, computer 1
1, the electric heater relay 12 is switched and operated to start energizing the particulate ignition heater 32 and the filter preheating heater 31.
Cut off the power to the

Note that the reason why the bypass valve 6 is opened at the same time as the electric heater is energized is to prevent the temperature of the electric heater from being lowered by the exhaust gas. 5, and only about 10% of the exhaust gas flows to the side where the particulate trap 4 is located, which prevents the temperature of the electric heaters 31 and 32 from lowering. To open the bypass valve 6, the negative pressure switching valves 9 and 10 are switched and actuated in response to a command from the computer 11, and negative pressure is introduced into the bypass valve driving actuator 7 to open the bypass valve 6.

The filter 36 reaches the ignition temperature by the particulate ignition heater placed in the center of the front surface of the filter 36, and the particulate collected in the filter 36 begins to burn, using this as a heat source to self-combust downstream and burn out. be done. The power required in this case is 500W, and the power density is 100W/cm ² because it is concentrated only in the center of the filter 36, compared to conventional devices of this type that do not have a heater for preheating the filter. Power density can be significantly increased.

In this way, in this embodiment, when the filter is regenerated, electric power is concentrated in the central part of the filter 36 to improve the ignition ability in that part, and the front peripheral part of the filter 36 is heated by the heater 3 for preheating the filter.
1, the particulate ignition heater 32 is preheated before activation and only the surface thereof is combusted, so the combustion effect of the particulate in the center of the filter 36 spreads more toward the periphery. As shown in the figure, the collected particulate matter is burned out over the entire area of the filter 36 by a part A that is combusted by the filter preheating heater 31 and a part B that is combusted by the particulate matter ignition heater 32. , which improves the ignition ability of electric heaters with less electric power.

Further, by installing the filter preheating heater 31, ignition can be sufficiently achieved even if the electric heaters 31, 32 and the front surface of the filter 36 are separated by about 1 to 2 mm.

Note that the higher the preheating temperature of the filter preheating heater 31, the lower the power consumption.
The preheating temperature of the preheating heater is preferably determined as appropriate in consideration of the specifications of the engine.

Effects of the Invention The present invention, when igniting the particulate matter collected on the filter using an electric heater, installs a filter preheating heater to preheat the required portions of the filter prior to full-scale ignition. By improving its ignition ability, it is possible to reduce power consumption, and by improving its water landing ability, it is possible to regenerate the filter even if there is a certain distance between the electric heater and the filter. This has various effects such as there is no risk of damage to the electric heater due to placing it too close to the filter, and there is no need for strict accuracy control in assembling the electric heater.

[Brief explanation of drawings]

Fig. 1 is a system diagram of the entire diesel engine equipped with the filter regeneration device of the present invention, Fig. 2 is an enlarged front view of an embodiment of the present invention, and Fig. 3 is the arrangement of the filter preheating heater and the particulate ignition heater. FIG. 3 is a side view conceptually showing the state. 1... Diesel engine body, 3... Exhaust path, 4
...Party cure trap, 5...Bypass passage, 6...Bypass valve, 30...Flange for supporting electric heater, 31...Heater for filter preheating, 32...Heater for particulate ignition, 33...Electric heater power supply terminal, 34...For power supply Connector, 35... Stay for supporting electric heater.

Claims (1)

[Scope of Claims] 1. A filter regeneration device in an exhaust gas purification device for a diesel engine, which includes two types of heaters, a filter preheating heater and a particulate ignition heater, provided in front of the filter. 2. A filter regeneration device in a diesel engine exhaust purification device according to claim 1, wherein the preheating heater is provided at the periphery of the filter, and the particulate ignition heater is provided at the center of the filter.