JP2015098834A - Catalyst device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst device for an internal combustion engine, capable of preventing/suppressing the formation of an electric leakage path due to condensed water and at the same time facilitating the positioning of one catalyst part relative to the other.SOLUTION: A catalyst device 1A for the internal combustion engine includes an outer cylinder 2, an electric heating type catalyst part 3 held in the outer cylinder 2 via a first mat 5, a downstream side catalyst part 4 provided on the downstream side of the electric heating type catalyst part 3 and held in the outer cylinder 2 via a second mat 6, and a spacer 7A provided between the first and second mats 5 and 6 in the state of contacting the electric heating type catalyst part 3 and the downstream side catalyst part 4, and having such a cylindrical shape that the inside of a lower part 7a extends to the further radial inside than the inside of an upper part 7b. An insulating material is applied to the inner face of the outer cylinder 2. For example, an insulating mat is applicable for the spacer 7A.

Description

  The present invention relates to a catalyst device for an internal combustion engine.

  2. Description of the Related Art A catalyst device including an electrically heated catalyst unit that can be heated by energization is known (see, for example, Patent Document 1). Patent Document 1 discloses an electrically heated catalyst device including a downstream catalyst portion on the downstream side of an electrically heated catalyst portion. Patent Document 2 discloses a tandem metal carrier in which an intermediate outer cylinder into which a thin honeycomb body is inserted is held by a retainer. Patent Document 3 discloses a monolith converter including a spacer for maintaining a space between a plurality of monolith catalysts divided in the axial direction.

JP 2012-21488 A Japanese Utility Model Publication No. 6-80814 Japanese Utility Model Publication No. 63-79426

  As disclosed in Patent Document 1, the electrically heated catalyst unit and the downstream catalyst unit can be held on the outer cylinder via a common mat having insulating properties, for example. However, the exhaust contains moisture. For this reason, in this case, there is a possibility that a leakage path from the electrically heated catalyst part to the non-insulating part is formed on the mat by the condensed water. As a result, there is a possibility that electric leakage may occur during energization of the electrically heated catalyst unit.

  An appropriate interval is required between the electrically heated catalyst part and the downstream catalyst part in order to avoid occurrence of substrate cracking due to thermal stress. And the positioning for that requires the device for avoiding the occurrence of the base material crack due to the thermal stress. Specifically, for example, in order to secure an appropriate interval, it is necessary to manage the press-fitting allowance. For this reason, positioning between the electrically heated catalyst part and the downstream catalyst part is not always easy.

  In view of the above problems, an object of the present invention is to provide a catalyst device for an internal combustion engine that can prevent or suppress the formation of a leakage path due to condensed water and at the same time facilitate positioning between catalyst parts.

  The present invention provides an outer cylinder, an electrically heated catalyst part held in the outer cylinder via a first mat, and a second mat in the outer cylinder on the downstream side of the electrically heated catalyst part. Is provided between the first and second mats in contact with the electrically heated catalyst unit and the downstream catalyst unit, and the lower part inside is more than the upper part inside. A catalyst device for an internal combustion engine comprising a spacer having a cylindrical shape extending radially inward.

  According to the present invention, the formation of a leakage path due to condensed water can be prevented or suppressed, and at the same time, the positioning of the catalyst portion can be facilitated.

1 is a schematic configuration diagram of a catalyst device for an internal combustion engine according to Embodiment 1. FIG. FIG. 3 is a schematic configuration diagram of a catalyst device for an internal combustion engine according to a second embodiment. FIG. 5 is a schematic configuration diagram of a catalyst device for an internal combustion engine according to a third embodiment. FIG. 6 is a schematic configuration diagram of a catalyst device for an internal combustion engine according to a fourth embodiment. FIG. 10 is a schematic configuration diagram of a catalyst device for an internal combustion engine according to a fifth embodiment. FIG. 10 is a schematic configuration diagram of a catalyst device for an internal combustion engine according to a sixth embodiment. FIG. 9 is a schematic configuration diagram of a catalyst device for an internal combustion engine according to a seventh embodiment.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a catalyst device (hereinafter referred to as catalyst device) 1A for an internal combustion engine. FIG. 1 shows a front view of the spacer 7A together with a cross-sectional view of the catalyst device 1A. The catalyst device 1A includes an outer cylinder 2, an electrically heated catalyst unit 3, a downstream catalyst unit 4, a first mat 5, a second mat 6, and a spacer 7A. The outer cylinder 2 constitutes a part of the exhaust pipe of the internal combustion engine. The outer cylinder 2 has conductivity. An insulating material is applied to the inner surface of the outer cylinder 2. The insulating material is, for example, a glass coat.

  An electrically heated catalyst unit 3 is held in the outer cylinder 2. The electrically heated catalyst unit 3 is heated by generating heat when energized. Specifically, the electrically heated catalyst unit 3 is configured to include an energizing exothermic base material and a metal catalyst. The energization exothermic base material is formed from a material that generates heat when energized, and allows exhaust to circulate. A porous body having a cell structure made of a non-metallic material or a metallic material that can be heated by energization can be applied to the energizing exothermic base material. The porous body may have a regular cell structure or an irregular cell structure. The metal catalyst is supported on the surface of the energization exothermic base material. An appropriate metal may be applied to the metal catalyst.

  A downstream catalyst portion 4 is held in the outer cylinder 2. The downstream side catalyst unit 4 is a catalyst in a form other than the electrically heated catalyst unit 3, specifically a three-way catalyst. Other types of catalysts may be applied to the downstream catalyst unit 4. The outer diameters of the catalyst parts 3 and 4 are set to the same size. The electrically heated catalyst unit 3 is held in the outer cylinder 2 through the first mat 5, and the downstream catalyst unit 4 is held in the outer cylinder 2 through the second mat 6. The mats 5 and 6 are holding members and have insulating properties. The total length of the first mat 5 is set according to the total length of the electrically heated catalyst unit 3. The total length of the second mat 6 is set in accordance with the total length of the downstream side catalyst unit 4. As the mats 5 and 6, ceramic fiber mats (for example, alumina mats) can be applied.

  The spacer 7 </ b> A is provided between the mats 5 and 6. The spacer 7 </ b> A is provided in contact with the electrically heated catalyst unit 3 and the downstream catalyst unit 4. Specifically, the spacer 7 </ b> A is provided in contact with the end faces of the catalyst parts 3 and 4. The spacer 7A has a cylindrical shape. The spacer 7A has an insulating property. As the spacer 7A, an insulating mat (for example, a mat made of ceramic fiber) which is difficult to apply thermal stress to the base material of the catalyst portions 3 and 4 can be applied.

  Specifically, the spacer 7 </ b> A includes a lower part 7 a and an upper part 7 b that extend radially inward from the outer diameters of the catalyst parts 3 and 4. The inner side of the lower part 7a extends radially inward from the inner side of the upper part 7b. The lower portion 7a is a portion positioned below in a use state (for example, a state provided in the vehicle together with the internal combustion engine), and the upper portion 7b is the opposite. The spacer 7A is formed in a cylindrical shape having an inner diameter larger than the outer diameters of the catalyst parts 3 and 4 at portions other than the lower part 7a and the upper part 7b. The inner diameter may be substantially equal to the outer diameter of the catalyst parts 3 and 4.

  The moisture contained in the exhaust gas is likely to condense in the outer cylinder 2 and accumulate downward, but in the catalyst device 1A, the volume of the lower portion 7a is increased. For this reason, the catalyst device 1 </ b> A can prevent the condensed water from being connected between the mats 5 and 6. As a result, the formation of a leakage path due to condensed water can be suppressed. At the same time, the catalyst device 1A can facilitate the positioning of the catalyst parts 3 and 4 with the spacer 7A. Moreover, if the spacer 7A is an insulating mat, the base material cracking of the catalyst portions 3 and 4 due to the spacer 7A can be prevented or suppressed.

  FIG. 2 is a schematic configuration diagram of the catalyst device 1B. FIG. 2 shows a front view and a side view of the spacer 7B and the ring member 8 together with a cross-sectional view of the catalyst device 1B. The catalyst device 1B includes a spacer 7B instead of the spacer 7A. Further, a ring member 8 is further provided. Except for these points, the catalyst device 1B is substantially the same as the catalyst device 1A. The spacer 7B is substantially the same as the spacer 7A except for the points described below.

  The spacer 7B has an inner diameter smaller than the outer diameter of the catalyst parts 3 and 4. The spacer 7B does not have an insulating property. The spacer 7B may have an insulating property. The ring member 8 is provided adjacent to the spacer 7B from both sides. The ring member 8 has insulating properties and water shielding properties. For the ring member 8, for example, ceramic having insulating properties and water shielding properties can be applied. The ring member 8 has an inner diameter larger than the outer diameter of the catalyst parts 3 and 4. The inner diameter of the ring member 8 may be approximately the same as the outer diameter of the catalyst portions 3 and 4. It is possible to apply the spacer 7A instead of the spacer 7B.

  In the catalyst device 1 </ b> B, the ring member 8 prevents the condensed water from being connected between the mats 5 and 6. As a result, it is possible to prevent a leakage path from being formed. Since the ring member 8 has an inner diameter larger than the outer diameter of the catalyst parts 3 and 4, the contact between the spacer 7 </ b> B and the catalyst parts 3 and 4 is also possible. For this reason, the catalyst device 1B can also facilitate the positioning of the catalyst parts 3 and 4 by the spacer 7B. The catalyst device 1 </ b> B can prevent the catalyst parts 3 and 4 from cracking the base material by avoiding contact between the catalyst parts 3 and 4 and the ring member 8.

  FIG. 3 is a schematic configuration diagram of the catalyst device 1C. In FIG. 3, the front view of the spacer 7C is shown with the sectional view of the catalyst device 1C. The catalyst device 1C is substantially the same as the catalyst device 1B except that the spacer device 7C is provided instead of the spacer 7B and the ring member 8 is not provided. The spacer 7C is substantially the same as the spacer 7B except that it has an insulating property. The catalyst device 1C can suppress the formation of a leakage path by the spacer 7C. Further, the positioning of the catalyst parts 3 and 4 can be facilitated by the spacer 7C.

  FIG. 4 is a schematic configuration diagram of the catalyst device 1D. In FIG. 4, the front view of spacer 7D is shown with sectional drawing of catalyst apparatus 1D. The catalyst device 1D is substantially the same as the catalyst device 1C except that a spacer 7D is provided instead of the spacer 7C. The spacer 7D is substantially the same as the spacer 7C except for the following points.

  That is, the spacer 7 </ b> D includes protrusions 7 c to 7 f that are a plurality of protrusions extending radially inward from the outer diameters of the catalyst parts 3 and 4. In the spacer 7D, portions other than the protrusions 7c to 7f are formed in a cylindrical shape having an inner diameter larger than the outer diameter of the catalyst portions 3 and 4. The protrusion 7c, which is one of the protrusions 7c to 7f, is disposed below. The protrusions 7c to 7f are arranged uniformly along the circumferential direction. The catalyst device 1D can suppress the formation of a leakage path by the protrusion 7c. Further, the positioning of the catalyst parts 3 and 4 can be facilitated by the protrusions 7c to 7f.

  FIG. 5 is a schematic configuration diagram of the catalyst device 1E. The catalyst device 1E is substantially the same as the catalyst device 1C except that a spacer 7E is provided instead of the spacer 7C. The spacer 7E is substantially the same as the spacer 7C except for the following points. That is, the spacer 7E has a tapered inner surface shape that widens toward the downstream side from the upstream side. In the spacer 7E, the inner diameters at both ends are set smaller than the outer diameters of the catalyst parts 3 and 4. The same change can be applied to the inner surface of at least the cylindrical portion of the spacers 7A, 7B, and 7D. The catalyst device 1E can further suppress the generation of pressure loss by the spacer 7E.

  FIG. 6 is a schematic configuration diagram of the catalyst device 1F. The catalyst device 1F is substantially the same as the catalyst device 1C except that a spacer 7F is provided instead of the spacer 7C. The spacer 7F is substantially the same as the spacer 7C except for the following points. That is, the spacer 7 </ b> F has an inner surface shape that protrudes in an arc shape radially inward in a cross section including the central axis. In the spacer 7 </ b> F, the inner diameters at both ends are set smaller than the outer diameters of the catalyst parts 3 and 4. The same change can be applied to the inner surface of at least the cylindrical portion of the spacers 7A, 7B, and 7D. The catalyst device 1F can further suppress the thermal stress applied to the catalyst parts 3 and 4 by the spacer 7F.

  FIG. 7 is a schematic configuration diagram of the catalyst device 1G. The catalyst device 1G is substantially the same as the catalyst device 1A except for the points described below. That is, the catalyst device 1 </ b> G includes first and second partial mats 5 a and 5 b instead of the first mat 5. Further, third and fourth partial mats 6a and 6b are provided instead of the second mat. The catalyst device 1G may have a configuration in which at least one of the mats 5 and 6 is changed in this way. Similar changes can be applied to the catalyst devices 1B to 1F.

  The partial mats 5 a and 5 b are both shorter than the entire length of the electrically heated catalyst unit 3. The partial mats 5a and 5b are provided such that a space S1 is formed therebetween. Specifically, the partial mats 5 a and 5 b are provided so as to hold both end portions of the electrically heated catalyst unit 3. The partial mats 6 a and 6 b are shorter in overall length than the entire length of the downstream catalyst unit 4. The partial mats 6a and 6b are provided such that a space S2 is formed therebetween. Specifically, the partial mats 6 a and 6 b are provided so as to hold both end portions of the downstream side catalyst portion 4. Both the partial mats 5a and 5b and the partial mats 6a and 6b have insulating properties.

  Even if the condensed water enters the first partial mat 5a, the catalyst device 1G can make it difficult for the condensed water to enter the second partial mat 5b from the first partial mat 5a. The same applies to the partial mats 6a and 6b. For this reason, the catalyst device 1G can suitably prevent or suppress the formation of a leakage path due to condensed water.

  The catalyst device 1G can enhance the heat retention of the electrically heated catalyst unit 3 by the space S1. Moreover, the heat retention of the downstream catalyst part 4 can be improved by the space S2. The spaces S1 and S2 can promote the evaporation of the condensed water that is to form the leakage path by increasing the heat retaining properties of the catalyst units 3 and 4. As a result, by exhibiting the effect of increasing the insulating property of the catalyst device 1G, it is possible to suitably prevent or suppress the formation of a leakage path due to condensed water.

  An insulating heat insulating material may be further provided in the spaces S1 and S2. In this case, the insulation of the catalyst device 1G can be further increased by further increasing the heat retaining properties of the catalyst units 3 and 4. The catalyst device 1 </ b> G can also improve the heat retaining properties of the catalyst parts 3 and 4 by applying an insulating material to the inner surface of the outer cylinder 2.

  The above embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to these, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

Catalyst device 1A, 1B, 1C, 1D, 1E, 1F, 1G
Outer cylinder 2
Electric heating type catalyst part 3
Downstream catalyst part 4
First mat 5
Second mat 6
Spacer 7A, 7B, 7C, 7D, 7E, 7F

Claims (1)

An outer cylinder,
An electrically heated catalyst portion held in the outer cylinder via a first mat;
A downstream catalyst part held in the outer cylinder via a second mat on the downstream side of the electrically heated catalyst part;
A cylindrical shape provided between the first and second mats in contact with the electrically heated catalyst part and the downstream catalyst part, with the lower part inside extending radially inward from the upper part inside A catalyst device for an internal combustion engine comprising a spacer having

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