JPH0510732U - Catalyst heating device for internal combustion engine - Google Patents

Abstract

(57) [Summary] [Object] To reduce the ventilation resistance of exhaust gas and prevent the output of an internal combustion engine from decreasing in a catalyst heating device used for an exhaust gas purification device using a catalytic converter equipped with an electrothermal heating device. [Constitution and Effect] In the catalyst heating device of the present invention, the ceramic insulator 5 having a shape along the inner wall cross-sectional shape of the frame body 6 having the curved inner wall surface is mounted along the inner wall surface by using the elastic material 14. The bent portion of the heater element is held by the ceramic insulator. As a result, it is possible to reduce the protrusion of the exhaust gas of the ceramic insulator toward the center of the passage, and to reduce the ventilation resistance of the exhaust gas.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a catalyst heating device used in an exhaust gas purifying device for an internal combustion engine using a catalytic converter.

[0002]

[Prior Art]

 For the purpose of purifying the exhaust gas of an internal combustion engine, an exhaust gas purifying device that mounts a three-way catalytic converter in the exhaust gas passage and controls the air-fuel ratio by an oxygen sensor is often used. However, the catalyst used in the exhaust gas purifying device is It has the property that it does not become fully active unless the temperature rises above 350 ° C. Therefore, in order to improve the exhaust gas purification efficiency at the cold start, it is necessary to mount an electrothermal heating device in the vicinity of the catalytic converter and heat the exhaust gas or the catalytic converter by energizing the internal combustion engine at the start.

However, since the heater element used in the electrothermal heating device reaches a high temperature of about 1000 ° C. during heating, it causes an electrical short circuit due to extension of the heater element or deformation during use, and normal heating is performed. May lose function.

In order to suppress such extension or deformation of the heater element and prevent an electrical short circuit, a ceramic insulator formed so that the bent portion of the heater element is housed is provided in the exhaust gas passage. There has been proposed a structure in which the heater element is attached by using an elastic material and is held (see FIG. 2).

[0005]

[Problems to be solved by the device]

 Since the ceramic insulator used in the above-mentioned prior art is formed in a shape formed by a straight line, when the inner wall surface of the frame body has a curved section (for example, a circular shape), Since the ceramic insulator is largely protruded toward the center of the exhaust gas passage, the ventilation resistance of the exhaust gas is increased, resulting in a decrease in the output of the internal combustion engine.

An object of the present invention is to reduce the ventilation resistance of exhaust gas in a catalyst heating device used in an exhaust gas purification device using a catalytic converter equipped with an electrothermal heating device, and prevent the output of an internal combustion engine from decreasing.

[0007]

[Means for Solving the Problems]

 As a means for solving the above problems, the present invention relates to an exhaust gas purifying apparatus for an internal combustion engine, which is equipped with an electrothermal heating device in the vicinity of a catalytic converter, and has an inner wall cross-sectional shape of a frame body having a curved inner wall surface. An object of the present invention is to provide a catalyst heating device in which a shaped ceramic insulator is mounted along the inner wall surface using an elastic material, and a bent portion of a heater element is held by the ceramic insulator.

[0008]

[Effect of the device]

 In the catalyst heating device of the present invention, the ceramic insulator for holding the heater element has a shape along the inner wall surface of the frame body, and the ceramic insulator is mounted along the inner wall surface of the frame body. The amount of protrusion to the center is reduced, and the ventilation resistance of exhaust gas can be reduced. As a result, it has become possible to maintain a high output of the internal combustion engine.

Further, since the heater element is arranged more generally than the catalyst heating device of the prior art with respect to the cross section of the exhaust gas passage, heating unevenness of the exhaust gas or the catalytic converter at the time of starting the internal combustion engine is reduced, and the catalyst It is also effective in improving the exhaust gas purification efficiency of the converter.

[0010]

【Example】

 The catalyst heating device of the present invention will be described with reference to the embodiment shown in FIG. The catalyst heating device 1 comprises a meandering ribbon-shaped heater element 2, a current-carrying terminal portion 3, a ceramic insulator 4, and a frame body 5 having a circular inner wall cross-sectional shape, and an end portion 6 of the heater element 2 is energized. In the terminal portion 3 for use, a bolt 9 is fastened with a washer 10 and a nut 11 while maintaining electrical insulation via the frame body 5 and the mica-like insulating material 7. Further, a ceramic insulator 4 having a bottomed hole 12 formed in conformity with the shape of each bent portion 2 ′ of the heater element and having a shape along the inner wall cross-sectional shape of the frame body 5 is a plate as the elastic material 13. It is pressed and fixed along the inner wall of the frame body 5 by using a spring. Each bent portion 2 ′ of the heater element is inserted into the bottomed hole 12 provided in the ceramic insulator 4 with a proper gap enough to accommodate the extension of the heater element and holds the heater element 2. It is configured to do. The catalyst heating device thus obtained is installed upstream or in the middle of the catalytic converter and used as an exhaust gas purifying device.

The catalyst heating device having such a structure prevents an electrical short circuit due to extension or deformation of the heater element, and since the ceramic insulator is less likely to protrude toward the center of the exhaust gas passage, the ventilation resistance of the exhaust gas is small. Therefore, when mounted in the exhaust gas passage of the internal combustion engine, the output of the internal combustion engine does not decrease. Further, since the heater elements are evenly arranged in the cross section of the passage of the exhaust gas, temperature unevenness during heating hardly occurs and exhaust gas purification efficiency is improved.

As described above, in the exhaust gas purifying apparatus for an internal combustion engine equipped with the catalyst heating device of the present invention, the ventilation resistance of the exhaust gas is reduced, and the output of the internal combustion engine can be maintained high.

The present invention is not limited to the range shown in the embodiment, and for example, the frame body 5 may be divided into two or more passages by one or more partition walls. Furthermore, the frame body 5 is applicable as long as a part of the inner wall cross section has a curved surface, and may have a flat surface portion. Further, as the elastic material 13, a coil spring may be used instead of the leaf spring.

Further, the insulator may be one in which ceramic is incorporated in a metal frame. Further, the gap between each bent portion of the heater element and the bottomed hole of the ceramic insulator may be filled with a ceramic fiber or a secondary molded body obtained by processing a ceramic fiber or the like. However, when using a secondary molded body in which all or part of the ceramic insulator is made by processing ceramic fibers or the like to give elasticity, it is necessary to provide a gap between the heater element and the secondary molded body. There is no.

Further, the heating device according to the present invention is mounted on the intake side of the internal combustion engine to be used for heating the combustion air, thereby preventing the intake resistance from increasing and increasing the combustion efficiency to improve the output of the internal combustion engine. It is also possible.

[Brief description of drawings]

FIG. 1 is a schematic view showing a cross-sectional structure of a catalyst heating device of the present invention.

FIG. 2 is a schematic view showing a cross-sectional structure of a conventional catalyst heating device.

[Explanation of Codes] 1 catalyst heating device 2 heater element 2'heater element bent portion 3 energizing terminal portion 4 ceramic insulator 5 frame body 6 heater element end portion 7 mica insulating material 9 bolt 10 washer 11 nut 12 bottomed hole 13 Elastic material

Claims (1)

Claims for utility model registration 1. In an exhaust gas purifying apparatus for an internal combustion engine, comprising an electrothermal heating device in the vicinity of a catalytic converter, a shape along a cross-sectional shape of an inner wall of a frame body having a curved inner wall surface. A ceramic heating device in which the ceramic insulator forming the element is mounted along the inner wall surface using an elastic material, and the bent portion of the heater element is held by the ceramic insulator.