JPH0521614Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an exhaust particulate treatment device for treating exhaust particulates discharged from a diesel engine.

[Conventional technology]

An exhaust particulate processing device is a device that once traps particulates in the exhaust gas in a filter, and when a predetermined amount of trapped particulates is reached, the trapped particulates are incinerated to restore the filter function.

Conventionally, a heat-resistant filter is placed inside the case, and a heating means such as a combustion burner or an electric heater is installed in parallel on the upstream side of the filter, and the exhaust particulates captured by the heat-resistant filter are heated by the heating means. Devices designed to cause the fire to burn out are known. Alternatively, instead of using the above-mentioned heating means, a heat-resistant filter carrying a catalyst is disposed inside the case, and the captured particles are incinerated by the heat-resistant filter itself, whose temperature is raised by the catalytic reaction. is also known. Furthermore, a device is known in which the ignition temperature of exhaust particulates discharged from a diesel engine is lowered by using fuel oil to which a catalyst is added.

[Problem that the invention attempts to solve]

All of the above conventional devices have the following problems. First, in a device that is equipped with a heat-resistant filter and a heating means, if a combustion burner is used as the heating means, the overall device will become larger, and if an electric heater is used, there is a limit to the heat generation temperature of the heater, and the exhaust gas must be circulated. However, if the current is applied, the disadvantage is that the temperature required to ignite the particles cannot be obtained. Next, in the case of using a heat-resistant filter carrying a catalyst, it is not possible to raise the temperature of the heat-resistant filter to a predetermined temperature over the entire operating range of a diesel engine. In particular, during low-load operation, the temperature does not reach the point where the captured particulates are ignited. Furthermore, when using fuel with a catalyst added, the metal components that make up the catalyst are emitted, which can clog the filter early, form deposits in the engine cylinder, and cause the catalyst to be released into the atmosphere along with the exhaust gas. It has the disadvantage that it poses a risk of being released into the environment and causing secondary pollution.

Furthermore, all of the above-mentioned filters have the problem that it is extremely difficult to make the temperature of the heat-resistant filter uniform. That is, in general,
Since the heat-resistant filter radiates a large amount of heat from the outer circumferential portion facing the case side, which is relatively low temperature, the center portion becomes high temperature, and a temperature gradient occurs between the central portion and the outer circumferential portion. If the temperature gradient exceeds a predetermined value, the heat resistant filter will be damaged.

[Means for solving problems]

A plurality of cylindrical heating elements consisting of porous SiC heating elements with one end closed and the other end open are placed in a case with an inlet and an exit, and each SiC heating element is energized. The structure was designed to allow

[Effect]

Particulates in the exhaust gas are captured while flowing through the SiC heating element. As the clogging progresses,
The SiC heating element is energized to raise its temperature and burn out the captured particles. The SiC heating element raises its temperature to above the ignition temperature of particulates, and restores the filter function as appropriate over the entire engine operating range when the heating element becomes clogged. The exothermic body serves both as an exothermic body and as a heating element. Since the SiC heating elements can be individually energized, a large amount of electricity can be supplied to the SiC heating elements on the outer periphery.

〔Example〕

1 and 2 show an embodiment of the present invention, in which a heat generating body 4 is disposed within a cylindrical case 3 provided with an inlet and an outlet 1 and an outlet 2. The heating element 4 is constructed by inserting a plurality of SiC (silicon carbide) heating elements 8 into a disk-shaped porous support plate 6 made of heat-resistant inorganic fiber or ceramic material. The SiC heating element 8 is porous and has a cylindrical shape with one end closed and the other end open. The heat generating body 4 is disposed inside the case 3 with a cushioning material 10 attached to the outer periphery of the porous support plate 6.

The case 3 is provided with a pressure sensor 11 on its inlet side, and further has power distribution terminals 12 and 13. The inlet side of each SiC heating element 8 of the heating element 4 is connected to a control device 14 via a power distribution terminal 12, respectively. The outlet side of each SiC heating element 8 is grounded via a power distribution terminal 13, respectively. Pressure sensor 11 is connected to control device 14 . The control device 14 is connected to a power source such as a battery. The control device 14 receives engine operating signals such as exhaust temperature, exhaust pressure, and rotation speed, and controls the heat generating filter 4.
It acts to supply current to the SiC heating element 8.

Exhaust gas flows in from the inlet 1 and passes through the exothermic body 4.
It passes through the inside of the SiC heating element 8 from the outside and flows out toward the outlet 2 from the open end. While flowing through the SiC heating element 8, the exhaust gas is filtered to separate out the fine particles it contains and discharged to the atmosphere through the outlet 2. When the trapping of particulates in the exothermic body progresses and a predetermined degree of clogging occurs, the pressure sensor 11 sends a signal to the control device 14. At the same time, signal information such as exhaust temperature and engine speed is input to the control device 14. Such a signal is processed by the control device 14, and a current is appropriately supplied to the heating element 4 to cause the SiC heating element 8 to generate heat. For example, when a certain clogging condition is reached,
The SiC heating element generates heat, and the fine particles captured on the outer surface of the heating element 8 are burned away. When the particulates are burned out and the exhaust pressure decreases, the current supply is stopped. When generating heat from the heating element, it is also possible to energize a part of the SiC heating element 8 without energizing the entire SiC heating element 8.

In addition, if the inlet 1 and outlet 2 of case 3 are reversed,
If exhaust gas flows in from outlet 2, exhaust particulates will be removed.
It is captured inside the SiC heating element 8. in this case,
The temperature inside the SiC heating element 8 increases quickly, and the captured particulates are easily combusted. The SiC heating element 8 of the heating element 4 has a heat resistance of up to approximately 1600°C, and has the property of being able to raise the temperature of the exhaust gas by 100 to 300°C more than when an electric heater is used. There is.

[Effect of idea]

As described above, the present invention forms a heat generating body made of a plurality of cylindrical SiC heat generating elements, one end of which is closed and the other end of which is open, in a case provided with an inlet and an outlet.
Since each of the SiC heating elements can be energized, it is possible to simultaneously perform a high temperature heating action and an overheating action without causing thermal damage to the heat generating filter, and without increasing the size of the entire device. Provides the desired exhaust particulate treatment.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the exhaust particulate treatment apparatus of the present invention, and FIG. 2 is a partial side sectional view of FIG. 1. 3...Case, 4...Exothermic body, 8...SiC
heating element.

Claims (1)

[Scope of utility model registration request] Inside a case with an inlet/outlet, a heat generating filter consisting of a plurality of cylindrical porous SiC heating elements with one end closed and the other end open is arranged, and each of the SiC heating elements can be energized. Exhaust particulate processing equipment.