JPH0623707Y2 - Exhaust gas filter overheat prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an exhaust gas filter overheat prevention device for removing unburned materials in exhaust gas of an internal combustion engine.

[Prior Art] As shown in FIG. 4, the exhaust gas burned in the internal combustion engine 6 is
After being discharged from the exhaust manifold 7 to the exhaust pipe 8 and being silenced by the silencer 9, unburned substances (patty culate) are removed by the filter 14 and discharged from the exhaust pipe 17 to the outside. The filter 14 is composed of a ceramic molded body that extends from the inlet side to the outlet side and has a large number of narrow passages communicating with each other on the way, and unburned components are removed in the passage while the exhaust gas passes. The unburned matter removed by the filter 14 is exposed to high temperature by electric heat to send combustion air to re-combust, or the high temperature combustion gas generated in the combustor 19 is sent to the filter 14 from the combustion gas supply pipe 18. It is burnt again and removed. As a result, the filter 14 is reproduced.

During the regeneration period of the filter 14, the switching valve 11 closes the exhaust pipe 12 on the inlet side of the filter 14, and the exhaust gas from the silencer 9 is discharged to the outside via the bypass pipe 10.

The clogging state of the filter 14 depends on the pressure sensors 13 and 16 arranged on the inlet side and the outlet side of the filter 14 and the internal combustion engine 6
Is detected from the signals of the load sensor 3 that is installed opposite to the fuel control rod of the fuel injection pump 2 and the rotational speed sensor 4 that is installed opposite to the flywheel 5 of the internal combustion engine 6. With the output of the electronic control unit 21 which receives these signals as input, the switching valve 11 is switched, the combustor 19 and the fuel ignition device 20 are driven, the combustion gas is sent to the filter 14, and the filter 14 is regenerated.

When the filter 14 is regenerated, the fuel ignition device 20 and the combustor 19 are stopped, the switching valve 11 is returned, and the exhaust gas from the silencer 9 is discharged to the exhaust pipe 17 through the filter 14.

By the way, when the high temperature combustion gas is sent to the filter 14 to burn the unburned matter as described above, the filter 1 is changed from the state of the flow of the combustion gas as indicated by the symbol A in FIG.
Unburned material is likely to remain in the periphery of the inlet side of No. 4. In particular, although the combustion gas spreads to some extent and flows through the center of the filter 14, if the unburned material in the center is removed early,
Combustion gas flows more easily through the center. When the temperature of the combustion gas is increased in order to burn the unburned material in the peripheral portion A that is easily cooled from the outside, the temperature of the outlet side center portion C of the filter 14 becomes abnormally high, and the filter 14 may be melted and damaged. There is.

In order to make the temperature distribution inside the filter uniform, for example, in the technique disclosed in Japanese Utility Model Laid-Open No. Sho 59-114408, although the combustion gas on the inlet side is deflected to the surroundings by a straightening plate, unburned matter is generated. When reburned, the center of the filter 14 becomes hotter than the surroundings due to electric heat, and the filter 14 melts or cracks.

[Problems to be Solved by the Invention] In view of the above problems, an object of the present invention is to avoid abnormal temperature rise at the outlet of the filter, thereby promoting combustion of unburned materials in the peripheral portion of the filter and making the filter uniform. Another object of the present invention is to provide an exhaust gas filter overheat prevention device that can be regenerated.

[Means for Solving the Problem] In order to achieve the above object, the structure of the present invention axially supports a baffle plate that expands in a disk shape from a folded state at the outlet center of the filter, and keeps it at a predetermined temperature. As described above, the baffle plate is provided with the heat-actuated actuator for expanding the baffle plate.

[Operation] The baffle plates 33, 33a axially supported in a foldable manner arranged in the center of the outlet of the filter 14 expand into a disc shape when the temperature at the outlet of the filter exceeds a predetermined value, thereby causing the flow of combustion gas. Is deflected to the peripheral portion, and the oxygen concentration in the central portion of the filter 14 decreases. Therefore, the combustion temperature of the unburned material in the center is lowered, and the melting or cracking of the filter 14 is avoided.

BEST MODE FOR CARRYING OUT THE INVENTION As shown in FIGS. 1 and 2, a housing 31 for accommodating a cylindrical filter 14 has constrictions at both ends to form an inlet 31a and an outlet 31b. The filter 14 made of a ceramic molded body has a large number of narrow passages in the axial direction, and these passages communicate with each other on the way. Such filters 14 are known and will not be described further.

According to the present invention, the support shaft 32 is provided on the center side of the outlet of the filter 14.
A pair of semicircular baffle plates 33, 33a that can be expanded and contracted is supported by. That is, when the temperature at the outlet of the filter exceeds a predetermined value, the pair of baffle plates 33, 33a expands in a disk shape by the thermal actuator 22, and when the temperature becomes lower than the predetermined value, they fold each other as shown by the broken line. It will be in a state of being broken. Both ends of the hinge support shaft 32 are supported by bearings 34 on the peripheral wall portion of the housing 31.

As shown in FIG. 3, the heat-actuated actuator 22 is accommodated in an empty space provided on the outlet side of the filter 14. For example, as shown in FIG. 3, a strip made of a shape memory alloy is formed into a U shape. It is folded back, and the upper end is connected to the hinge part of the baffle plate 33a, and the lower end part is connected to the hinge part of the baffle plate 33, respectively.

When the heat-actuated actuator 22 is exposed to combustion gas and exceeds a predetermined temperature, the baffle plates 33 and 33a are expanded from the state shown by the broken line to a memorized shape, that is, a rhombus, and the baffle plates 33 and 33a are expanded around the support shaft 32, and the filter 14 Close the exit center. As a result, the flow of the combustion gas is deflected from the central portion to the peripheral portion, and the unburned materials in the entire filter are uniformly burned.

After the unburned material of the filter 14 is completely removed, the combustor 1
If the operation of 9 is stopped, the temperature at the outlet of the filter will drop,
The baffles 33 and 33a are in a state of being folded together,
Does not impede the flow of exhaust gas during normal engine operation.

In another embodiment of the heat-actuated actuator 22 shown in FIG. 4, one end of the heat-resistant metal plate 27 curved in a U shape or a rhombus is a hinge portion of the baffle plate 33, and the other end is a hinge portion of the baffle plate 33a. Be combined. Then, the bimetal 25 is joined between the heat-resistant metal plates 27 folded up and down. In this embodiment, when the temperature at the outlet of the filter becomes high, the bimetal 25 is elongated and the heat-resistant metal plate 27 is pushed and expanded, and the baffles 33 and 33a are expanded into a disc shape.

In the embodiment shown in FIG. 5, between the pair of heat-resistant metal plates 27 that are superposed on each other, the thermal expansion body 26 that replaces the bimetal 25
Are housed in a chamber between the cylinder and the piston, and when the temperature at the outlet of the filter exceeds a predetermined value, the piston and the cylinder relatively expand, and the pair of heat-resistant metal plates 27 are pushed apart from each other. The baffles 33 and 33a are expanded into a disc shape.

[Advantage of the Invention] As described above, the present invention axially supports the baffle plate that expands in a disc shape from the folded state at the outlet side center portion of the filter,
Since the baffle is equipped with a heat-actuated actuator that expands the baffle at a specified temperature or higher, the combustion gas introduced from the inlet to the filter causes unburned matter to be generated in the center of the filter before the surrounding area where heat loss is high. When combustion occurs and the combustion temperature rises, this temperature activates the thermo-responsive actuator, the baffle plate at the outlet of the filter expands into a disc shape, and the center of the outlet of the filter is closed, so the combustion gas flowing into the filter is closed. Is deflected to the peripheral portion, the temperature rise in the central portion is suppressed, and unburned matter in the peripheral portion of the filter is efficiently reburned. Therefore, burning or cracking due to local overheating of the filter is avoided, and the filter is regenerated as a whole as a whole.

[Brief description of drawings]

FIG. 1 is a side view showing a schematic structure of an exhaust gas filter overheat prevention device according to the present invention, FIG. 2 is a rear view of the same, FIG. 3 is a side view of a heat-actuated actuator, and FIGS. 4 and 5 are heat-actuated actuators. FIG. 6 is a side view showing another example of the above, FIG. 6 is an overall configuration diagram of an exhaust gas purifying apparatus for an internal combustion engine, and FIG. 7 is a side view illustrating an operation of a filter of the apparatus. 14: Filter, 22, 24: Heat-actuated actuator,
25: bimetal, 32: support shaft, 33, 33a: baffle plate

Claims (1)

[Scope of utility model registration request] 1. A heat-responsive actuator for axially supporting a baffle plate that expands into a disc shape from a folded state at the center of the outlet of the filter and expands the baffle plate at a predetermined temperature or more. An exhaust gas filter overheat prevention device characterized in that