JPH0544531B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an on-vehicle combustion device that efficiently regenerates a filter for removing particulates present in the exhaust gas of a diesel engine.

[Prior art]

Conventionally, this type of device does not exist, but its development is awaited for the following reasons. In other words, the amount of fine particles contained in the exhaust gas from diesel engines is being regulated because they are harmful to the human body. Regulations are already taking shape in the United States, and there are also moves toward regulations in Japan. By the way, there are two methods for reducing the amount of particulate emissions. One is to improve the diesel engine itself to reduce particulate emissions. However, although this method is ideal, it is currently only possible to expect a slight reduction, but it will not be possible if regulations become stricter.
Another method is to install a ceramic honeycomb filter, for example, in the exhaust system of a diesel engine to allow fine particles to pass through. Although this method has the disadvantage that the filter must be regenerated if it becomes clogged, it is the most effective. This filter regeneration is based on the following principle. In other words, the main component of the particles that adhere to the filter is carbon, and its ignition temperature is
Since the temperature is about 550℃, if the engine exhaust gas is heated above 550℃, the particulates will be converted into carbon dioxide and regenerated. However, when driving a diesel-equipped vehicle, the maximum exhaust gas temperature is around 400 degrees Celsius, making filter regeneration impossible. Therefore, it is necessary to add some type of heating device, and this heating device is a filter regeneration device.

Possible regeneration devices for this filter include a device that throttles the air supply to the engine to raise the exhaust gas temperature, a regeneration burner, etc., but both can accurately grasp the clogging status of the filter and start and end regeneration. Controlling the drive of the reproducing device by outputting a command is significant in improving the reliability of reproduction. By the way, possible means of detecting the timing of the start and end of regeneration include one based on the pressure loss upstream and downstream of the filter, or a timer linked to the engine operating time to perform regeneration at regular intervals for a fixed period of time. Since the exhaust gas flow rate constantly fluctuates and is affected by the driving conditions of the vehicle, an average method must be used, which lacks reliability. The latter also lacks reliability because it is the test result value of the former with a margin added.

[Summary of the invention]

This invention was made in view of the above-mentioned current situation. Carbon particles easily absorb radio waves with a dielectric material in order to understand the clogging status of filters, and radio waves can be used to detect the driving conditions of automobiles and the accompanying exhaust gas. This method focuses on the fact that it is not affected by the flow rate; in other words, when microwaves with low power are input into the filter from a magnetron, no power is applied to the carbon floating in space, and the transmitted power changes depending on the amount of carbon attached to the filter. Furthermore, the resonant frequency of the filter housing does not change before and after regeneration based on experimental data, and by comparing the detected value with the lower limit value of transmitted power stored in advance in the control device, the filter can be adjusted regardless of the driving conditions of the vehicle. The purpose of the present invention is to provide an on-vehicle combustion device in which regeneration is started depending only on the amount of carbon attached to the regeneration, and is ended by comparing an upper limit value with a detected value.

[Embodiment of the Invention] An embodiment of the invention will be described below with reference to the drawings. In the system configuration diagram shown in Figure 1, 1
is a diesel engine, 2 is an exhaust pipe of the engine 1, 3 is a filter provided in a part of the passage of this exhaust pipe 2 for trapping carbon particles, 4 is a filter housing for fixedly supporting the filter 3, 5 is a magnetron that generates microwaves, and 5a is a power supply device for the magnetron, which is a battery or an alternator. 6 is a reflector plate that prevents microwaves from leaking out of the filter housing 4; 7 is a reflector plate that prevents microwaves from leaking out of the filter housing 4;
8 is an antenna for detecting the microwave incident wave voltage and a converter for converting it into a control signal; 9 is a transmitted power; 10 is a control device whose input signals are the engine operating time and incident and transmitted power after the end of regeneration, and whose output signal is a magnetron drive signal. 11 is a muffler.
Further, FIG. 2 shows a flowchart showing an algorithm for starting and ending playback.

Next, the operation will be explained. During normal operation, that is, when the filter 3 is not regenerated, the exhaust gas discharged from the engine 1 passes through the exhaust pipe 2,
After the carbon particles are trapped by the filter 3, they are discharged into the atmosphere through the muffler 11. By the way, as the amount of carbon particles adhering to the filter 3 increases, the pressure loss before and after the filter 3 increases.
The fuel efficiency of the engine deteriorates and the engine output decreases. Therefore, a timer is provided to accumulate the engine operating time, and as shown in Fig. 2, a timer is provided that is linked to the engine operating time, and the magnetron 5 is driven at regular intervals to apply a small amount of electric power to the filter 3 so that the particulates do not become red hot. On the other hand, the transmitted power is detected by the detection antenna and the converter 9, and compared with the lower limit value stored in advance in the control device 10. If the detected value > the lower limit value, it is determined that the amount of adhesion is small and the magnetron is driven. is stopped until the next detection time, and if the detected value ≦ the lower limit value, a regeneration start command is output from the control device 10, the magnetron generates regeneration power (high power), and the carbon particles attached to the filter 3 are heated to red heat. At the same time, engine exhaust gas is introduced to cause oxygen in the exhaust gas to react with red-hot carbon particles, thereby performing regeneration. As the regeneration progresses and the amount of carbon particles adhering to the filter 3 decreases, the absorption of radio waves by the carbon particles decreases and the transmitted power increases. When the detected value is greater than or equal to the upper limit, the controller 10 outputs a regeneration end signal to stop driving the magnetron, integrates the engine operating time, and resets a timer that outputs a detection timing command.

〔Effect of the invention〕

As explained above, according to the present invention, the regeneration start and end times can be detected depending only on the amount of attached carbon particles without being affected by the driving conditions of the automobile, so that the regeneration start and end times can be detected depending only on the amount of attached carbon particles. This has the effect of improving reliability.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of an on-vehicle combustion apparatus showing an embodiment of the present invention, and FIG. 2 is a flowchart showing an algorithm for starting and ending filter regeneration. 1...Engine, 2...Exhaust pipe, 3...Filter, 4...Filter housing, 5...Magnetron, 6...Reflector, 7...Microwave supply path,
8... Incident power detection antenna and converter, 9...
...Transmitted power detection antenna and converter, 10...
Control device.

Claims (1)

[Claims] 1. A filter made of ceramic honeycomb installed in a part of the exhaust gas passage of a diesel engine to trap carbon particles in the exhaust gas, a filter housing for fixedly supporting the filter, and a microwave powered by a battery or alternator. A magnetron that generates electric power, a reflector plate installed at the front and rear ends of the filter housing to prevent leakage of microwaves, and a microwave that is electrically and mechanically coupled to the filter housing to transmit the microwaves generated from the magnetron. In an on-vehicle combustion device that is equipped with a control device that uses a supply path and a magnetron drive signal as an output signal, and that regenerates the filter by injecting microwave power into the filter and microwave-heating the carbon particles, the control device includes an engine operating system. A timer circuit linked to time is provided, and a small amount of power is injected from the magnetron at regular intervals, and an antenna and converter for detecting transmitted power is provided at the end of the filter housing, and the transmitted power is set to a lower limit stored in advance in the control device. A regeneration start signal is output only when it is below the judgment value, the power generated by the magnetron is switched to high power and regeneration is performed, and when the transmitted power exceeds the upper limit judgment value stored in advance in the control device, the regeneration ends. An on-vehicle combustion device characterized by outputting a signal, stopping driving of a magnetron, and terminating regeneration.