JPH0327732B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a particulate purification device for a diesel engine, and particularly to an electric heater provided in the particulate purification device.

Exhaust gas discharged from a diesel engine is passed through a trap installed in the exhaust passage, and particulates such as soot (hereinafter referred to as particulates) contained in the exhaust gas are passed through a porous ceramic material that constitutes the trap. It is collected by a collection material consisting of: As time passes, particulate accumulates in the trap, increasing pressure loss and increasing engine output loss. Therefore, before particulate accumulates to a certain extent and affects output, the particulate is incinerated and removed to regenerate the trap. There is a need.

This regeneration can be done either by placing an electric heater on the collection material and using the electric heater to directly ignite the particulate and burning it, or by restricting intake and exhaust air to raise the exhaust gas passing through the collection material to a temperature above the combustion temperature of the particulate. This is done by letting the heated exhaust gas burn the particulate. The same battery as the power source for other vehicle electrical components is used as the power source for the electric heater. Among these electrical components for vehicles, there are some that take priority over the above-mentioned electric heater, that is, it is undesirable if the voltage changes instantaneously when the electric heater is turned on or off. For example, head lamps. If you turn the electric heater on or off while the headlamp is on, the brightness of the headlamp will change momentarily at the moment you turn it on or off. In order to minimize changes in the brightness of the headlamp, it is possible to divide the electric heater into multiple parts and energize each heater separately, but in the case of distributed energization, the entire ignition time is energized at once. It takes longer than the case where the process is completed, which is unfavorable in terms of emission and fuel consumption. In other words, it has been thought that completing trap regeneration in a short time and minimizing voltage changes in vehicle electrical components such as headlamps are incompatible, and a solution to this problem has been desired.

The present invention aims to minimize momentary changes in the voltage of vehicle electrical components that occur when the electric heater is turned on and off while the vehicle electrical components are in operation, which takes priority over the electric heater, and to complete trap regeneration in a short time. The purpose of this invention is to provide a control structure for a particulate purification device for a diesel engine, particularly an electric heater, to achieve this goal.

In order to achieve this object, in the diesel engine particulate purification device of the present invention, the electric heater provided in the trap of the diesel engine is composed of a plurality of electric heaters, and the electricity supply to the electric heater is controlled by the electric heater. A computer connected to the energization control circuit is controlled so that when the vehicle electrical component is not in operation, a plurality of components are energized in a concentrated manner, and when the vehicle electrical component is in operation, the power is distributed in a distributed manner, that is, by reducing the number of instantaneously energized components. That is,
When it is time to regenerate the trap and the electric heater is energized, the energization pattern is differentiated depending on whether the vehicle electrical component that has priority over the electric heater is operating or not. The regeneration of the trap by the electric heater is carried out by central energization while the vehicle electrical components that have priority over the electric heater are not operating, and the trap regeneration period is unavoidably performed when the vehicle electrical components are operating. In this case, distributed energization, that is, the number of electric heater wires that are instantaneously energized is smaller than the number of electric heater wires that are energized during concentrated energization. By controlling the energization to the electric heater in this way, regeneration is performed in a short period of time with concentrated energization, and with distributed energization, changes in battery voltage are suppressed, and instantaneous changes in the voltage of the vehicle electrical components are suppressed. Minimized.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the diesel engine particulate purifying device of the present invention will be described below with reference to the drawings. In the following explanation, a headlamp will be taken as an example of a vehicle electrical component that has priority over an electric heater, that is, it is undesirable if the voltage changes instantaneously when the electric heater is turned on or off, but the present invention is not limited to headlamps.

FIG. 1 shows a system of an embodiment of a diesel engine particulate purification device according to the present invention. In the figure, 1 is an exhaust passage of a diesel engine, and 2 is a trap for collecting particulate matter in the exhaust gas. trap 2 against trap 2
A bypass passage 3 is provided for bypassing the air, and a bypass valve 4 is disposed in the bypass passage 3. The bypass valve 4 is opened and closed by a diaphragm 5, and the operation of the diaphragm 5 is
This is done by VSV6 and 7. One VSV6
is connected to the vacuum pump, and the other VSV7
leads to the atmosphere. A collection material 8 for collecting particulate matter is charged in the trap 2, and an electric heater 9 for igniting the collected particulate matter is provided upstream thereof.
This electric heater 9 is body grounded. Further, the trap 2 is provided with a temperature detection sensor 10, which detects, for example, the temperature of the incoming gas. The electric circuit of the electric heater 9 is provided with a battery 11 and an energization control circuit that controls energization from the battery 11 to the electric heater 9, such as a relay 12 that turns on and off the energization to the electric heater 9. The application of electricity to the electric heater 9 for regenerating the trap 2 is controlled by a computer 13 (ECU). When the ECU 13 determines that the regeneration time has come, the bypass valve 4 is opened by operating the VSVs 6 and 7, the relay 12 is turned on and the electric heater 9 is energized, and then the exhaust gas flows through the trap 2. Regeneration is performed by controlling the flow rate by opening and closing the bypass valve 4. The computer 13 has this control function. The electric heater 9 described above is configured as shown in FIG. That is, the electric heater 9 is composed of a plurality of electric heaters 9 (eight in the figure).

The power supply to the electric heater 9 is controlled by the ECU 13 as follows. That is, the ECU 13 first determines whether or not the trap regeneration time has come, and if it is the trap regeneration time, it determines whether the headlamp is turned off or turned on. When the headlamp is off, the eight electric heaters 9 are energized all at once or in a group, and when the headlamp is on, the eight electric heaters 9 are energized one at a time, or fewer heater wires than the number of heater wires are energized when the headlamp is off. The lights are turned on in sequence according to the number of instantaneously energized units, that is, they are energized in a distributed manner. Whether the headlamp is turned off or turned on is determined, for example, by the switching position of the light control switch 14, as shown in FIG. In FIG. 3, the contact 14a is connected to the left and right head lamps 1.
The contact point 14b is the position where only the tail lamp 17 is turned on, and the contact point 14c is the position where both the head lamps 15, 16 and the tail lamp 17 are not turned on. When the head lamps 15 and 16 are turned on, the contact 14a of the light control switch 14 is on, and when the other contact 14b is on and the contact 14c is on, the head lamps 15 and 16 are turned off. It's time. light control switch 14
and the ECU 13 are electrically connected, and receive a signal from the light control switch 14.
The ECU 13 determines whether the headlamp is turned on or off.

Next, the operation of the apparatus configured as described above will be explained.

In FIG. 1, the bypass valve 4 is normally closed and the exhaust gas flows through the trap 2.
Particulate matter in the exhaust gas is collected by the collection material 8, and the exhaust gas is purified and discharged into the atmosphere. When the cumulative engine speed is below a certain number of revolutions, for example 200,000 revolutions, the bypass valve 4 is kept closed and the entire amount of exhaust gas is passed through the trap 2 and collected by the particulate. has decided that it is time for a rebirth,
Open bypass valve 4. Subsequently, the electric heater 9 is energized by the relay 12 . At this time, as described above, the energization pattern is distinguished depending on whether the headlamps 15, 16 are lit or not. That is, the light control switch 14
It is determined whether the headlamps 15, 16 are on or not depending on the switching position of the headlamps 15, 16, and when the headlamps 15, 16 are on, the electric heaters 9 are energized one by one,
Minimize changes in headlamp brightness.
That is, if all eight electric heaters 9 are energized at the same time, the power consumption will be large and the voltage of the battery 11 will change greatly, resulting in a change in brightness that can be felt in the head lamps 15 and 16 powered by the same battery 11. However, when the electric heaters 9 are energized one by one, the instantaneous change in the voltage of the battery 11 is small, and the change in the brightness of the headlamps 15 and 16 is suppressed to a minimum. On the contrary, head lamp 15,
16 Since changes in brightness do not matter when the lights are off, there can be no problem with a large voltage drop in the battery voltage, and since no power is consumed by the headlamps 15 and 16, several or all of the electric heaters 9 are energized at once. Is possible. By energizing in this way, the time required to ignite the trap 2 during regeneration can be shortened.
It is preferable from the viewpoint of emission and fuel efficiency.

As explained above, the diesel engine particulate purification device of the present invention distinguishes the energization pattern to the electric heater depending on whether the vehicle electric component that has priority over the electric heater is operating or not, and When the vehicle electrical component is in operation, the electric heater wires are energized in a distributed manner, and when the vehicle electrical component is not in operation, several electric heater wires are energized in a concentrated manner. According to the present invention, the regeneration of the trap by the electric heater is performed in the vehicle. It is possible to carry out concentrated energization in a short time when the vehicle electrical components are not operating, which is advantageous in terms of emissions and fuel efficiency.Also, when the vehicle electrical components are operating and it is time to regenerate the trap, distributed energization is possible. This provides the effect that changes in the voltage of the vehicle electrical components can be suppressed to a minimum.

[Brief explanation of drawings]

Fig. 1 is a system diagram of one embodiment of the diesel engine particulate purification device of the present invention, Fig. 2 is a front view of the electric heater of the device of Fig. 1, and Fig. 3 is an electric circuit showing the light control switch circuit. Figure. 1... Exhaust passage, 2... Trap, 3... Bypass passage, 4... Bypass valve, 8... Collection material, 9... Electric heater, 11... Battery, 12
...Relay, 13 ...Computer (ECU), 1
4...Light control switch.

Claims (1)

[Claims] 1. A trap provided in the exhaust passage of a diesel engine is provided with a plurality of electric heaters, and the energization control circuit of the electric heater is set to take priority over the electric heater when the vehicle electrical components are not in operation. A particulate purification device for a diesel engine, characterized in that the particulate purification device for a diesel engine is connected to a computer that controls energization during trap regeneration so that a plurality of traps are energized in a concentrated manner and energized in a distributed manner when the vehicle electrical components are activated. 2. The vehicle electrical component is a headlamp,
A particulate purification device for a diesel engine according to claim 1, wherein turning off and turning on the headlamp corresponds to switching of a light control switch.