JP6136856B2 - Catalytic converter device - Google Patents

Description

  The present invention relates to a catalytic converter device provided in an exhaust pipe of an internal combustion engine.

In a catalytic converter device provided in an exhaust pipe for purifying exhaust gas generated by an internal combustion engine, for example, as described in Patent Document 1, an upstream side of exhaust gas is connected to an outer pipe with respect to a heating element that generates heat by energization. There is a double pipe structure of the inner pipe. In the structure described in Patent Document 1, the inner pipe extends to the upstream side of the exhaust gas while the inner diameter gradually decreases.
JP 2013-185573 A

  In the structure described in Patent Document 1, even if carbon or the like in the exhaust gas adheres to the inner pipe, the temperature of the inner pipe increases, so that the oxidation of carbon is promoted.

  In view of the above facts, an object of the present invention is to obtain a catalytic converter device that can suppress the temperature drop of the catalyst carrier and promote the combustion of carbon on the downstream side of the catalyst carrier.

  In the first aspect of the present invention, a catalyst carrier for purifying exhaust gas exhausted from an internal combustion engine is carried, the catalyst carrier is heated by energization, and the catalyst carrier is accommodated in a cylindrical shape. And an accommodation cylinder attached to the exhaust pipe, and a downstream side diameter-reduced diameter which is formed in a cylindrical shape, spaced from the catalyst carrier on the downstream side in the exhaust flow direction from the catalyst carrier, and the inner diameter is reduced toward the downstream side. And a downstream cylinder holding member that is disposed between the inner peripheral surface of the storage cylinder and the outer peripheral surface of the downstream cylinder and holds the downstream cylinder in the storage cylinder.

  In this catalytic converter device, when the catalyst carrier is heated by energization and heated up, and the temperature of the catalyst carrier is maintained, the purification effect by the supported catalyst is higher than in the case where the temperature is not raised. It can be demonstrated.

  A downstream cylinder is formed downstream of the catalyst carrier. The downstream cylinder is provided with a downstream-side reduced diameter portion, and the flow rate of exhaust gas is increased. Therefore, the temperature of the downstream cylinder is easily increased, and combustion of attached carbon is promoted.

  The downstream cylinder is separated from the catalyst carrier. Therefore, the heat of the catalyst carrier is not easily transmitted to the downstream cylinder. That is, the temperature drop of the catalyst carrier due to the heat of the catalyst carrier being transferred to the downstream cylinder can be suppressed.

  Since the downstream cylinder holding member is disposed between the inner peripheral surface of the storage cylinder and the outer peripheral surface of the downstream cylinder, the downstream cylinder is separated from the storage cylinder. Therefore, compared with the structure in which the downstream cylinder is in contact with the storage cylinder, the heat of the downstream cylinder is not easily transmitted to the storage cylinder. That is, it is possible to suppress the temperature drop of the downstream cylinder due to the heat of the downstream cylinder being transmitted to the housing cylinder, and to promote the combustion of carbon.

  According to a second aspect of the present invention, in the first aspect, a first glass coat layer provided on an inner peripheral surface of the housing cylinder and containing an inorganic substance, and provided on a surface of the downstream cylinder, the first glass coat layer And a second glass coat layer containing an inorganic substance having a particle size larger than that of the inorganic substance.

  Since the first glass coat layer is provided on the inner peripheral surface of the housing cylinder and the insulation between the housing cylinder and the catalyst carrier is high, it is possible to reliably supply a current to the catalyst carrier and raise the temperature.

  Moreover, since the 2nd glass coat layer is provided in the surface of the downstream cylinder, compared with the structure without a 2nd glass coat layer, adhesion of the carbon to a downstream cylinder can be suppressed.

The inorganic substance contained in the second glass coat layer has a larger particle size than the inorganic substance contained in the first glass coat layer. Therefore, than the friction between the holding cylinder and the downstream cylinder holding member, it is larger friction between the downstream cylinder and the downstream cylinder holding member. For this reason, when the downstream cylinder holding member is mounted and integrated around the downstream cylinder and the integrated member is press-fitted into the housing cylinder and assembled, the deviation between the downstream cylinder and the downstream cylinder holding member is suppressed, and the assembly is performed. It's easy to do.

  Since the present invention is configured as described above, it is possible to suppress the temperature drop of the catalyst carrier and to promote the combustion of carbon on the downstream side of the catalyst carrier.

1 is a cross-sectional view showing a catalytic converter device according to a first embodiment of the present invention in a cross section including a center line in an attached state to an exhaust pipe. It is sectional drawing which expands and shows the catalytic converter apparatus of 1st Embodiment of this invention partially. It is sectional drawing which expands partially and shows the catalytic converter apparatus of 1st Embodiment of this invention in the state in the middle of an assembly | attachment.

  FIG. 1 shows a catalytic converter device 12 according to a first embodiment of the present invention attached to an exhaust pipe 10. Hereinafter, the terms “upstream side” and “downstream side” refer to the upstream side and the downstream side in the flow direction of the exhaust gas in the exhaust pipe 10 (arrow F1 direction), respectively. The catalytic converter device 12 is attached between the upstream side exhaust pipe 10A and the downstream side exhaust pipe 10B.

  As shown in FIG. 1, the catalytic converter device 12 includes a catalyst carrier 14 formed of a material having conductivity and rigidity. As a material constituting the catalyst carrier 14, a conductive ceramic, a conductive resin, a metal, or the like can be applied. In the present embodiment, a conductive ceramic is particularly used.

  The catalyst carrier 14 is formed in a columnar shape or a cylindrical shape in which the surface area of the material is increased by configuring a thin plate having a honeycomb shape or a wave shape in a spiral shape or a concentric shape. A catalyst (platinum, palladium, rhodium, etc.) is attached and supported on the surface of the catalyst carrier 14.

  The catalyst has an action of purifying substances (hydrocarbons and the like) in the exhaust flowing through the exhaust pipe 10. Note that the structure for increasing the surface area of the catalyst carrier 14 is not limited to the honeycomb shape or the wave shape described above.

  Two electrodes 16A and 16B are attached to the catalyst carrier 14, and terminals 18A and 18B are connected to the electrodes 16A and 16B, respectively. By energizing the catalyst carrier 14 from the terminals 18A and 18B through the electrodes 16A and 16B, the catalyst carrier 14 can be heated. By this heating, the catalyst supported on the surface is raised in temperature so that the purification effect of the catalyst can be exerted to a high degree.

  The catalyst carrier 14 is held in a state of being accommodated inside a case cylinder 28 (accommodating cylinder according to the present invention) via a holding mat 26 arranged on the outer periphery. The holding mat 26 is formed in a fibrous shape having insulating properties and predetermined elasticity by using, for example, alumina mat, resin mat, ceramic wool, interlam mat, mullite, or the like.

  The case cylinder 28 is formed of a metal such as stainless steel in the present embodiment. The case cylinder 28 has a cylindrical housing cylinder 30 having a constant diameter from the upstream side to the downstream side, and an upstream side further downstream from the upstream end of the housing cylinder 30 and whose diameter is reduced stepwise. A side reduced diameter portion 32 is provided. In the example shown in FIG. 1, the upstream reduced diameter portion 32 is reduced in two stages by two reduced diameter portions 32C, but the number of reduced diameter portions 32C may be one or three or more.

  An upstream conical member 20 and a connecting member 22 are arranged between the housing cylinder 30 of the case cylinder 28 and the upstream exhaust pipe 10A. The upstream conical member 20 has a fixed cylinder 20A fixed around the entire circumference by welding or the like outside the upstream exhaust pipe 10A, and a fixed cylinder 20B fixed around the whole circumference by welding or the like inside the connection member 22. doing. The fixed cylinder 20B has a larger diameter than the fixed cylinder 20A, and the space between the fixed cylinder 20A and the fixed cylinder 20B is continued by a truncated cone portion 20C having a diameter gradually increased from the fixed cylinder 20A to the fixed cylinder 20B. Inside the fixed cylinder 20A, the upstream side exhaust pipe 10A protrudes to the downstream side inside the truncated cone part 20C, and the protruding part 10C is configured.

  The upstream reduced diameter portion 32 is located upstream of the catalyst carrier 14 and downstream of the truncated cone portion 20C. Therefore, two truncated cone-shaped members (the truncated cone portion 20 and the upstream reduced diameter portion 32) that are expanded from the upstream side toward the downstream side are provided side by side in the exhaust flow direction. .

  The upstream end 32S of the upstream reduced diameter portion 32 is located on the downstream side of the downstream end 10T of the upstream exhaust pipe 10A (projecting portion 10C), and the upstream exhaust pipe 10A and the upstream side contraction in the exhaust flow direction. It does not overlap with the diameter part 32 (does not wrap). A water storage region 36 is formed between the upstream conical member 20 and the connecting member 22 and the upstream reduced diameter portion 32. As will be described later, the water storage area 36 is an area in which condensed water (liquid water) obtained by condensing moisture in the exhaust gas is stored.

  The diameter D2 of the upstream end 32S of the upstream reduced diameter portion 32 is larger than the diameter D1 of the downstream end 10T of the upstream exhaust pipe 10A.

  A downstream cone member 50 is disposed between the housing cylinder 30 of the case cylinder 28 and the downstream exhaust pipe 10B. The downstream conical member 20 has a fixed cylinder 50A fixed around the entire circumference by welding or the like outside the downstream exhaust pipe 10B, and a fixed cylinder 50B fixed around the entire circumference by welding or the like inside the housing cylinder 30. doing. The fixed cylinder 50B has a larger diameter than the fixed cylinder 50A, and the fixed cylinder 50A and the fixed cylinder 50B are continuous by a truncated cone portion 50C that gradually increases in diameter from the fixed cylinder 50A to the fixed cylinder 50B.

  A downstream cylinder 40 is provided on the downstream side of the catalyst carrier 14. The downstream cylinder 40 is separated from the catalyst carrier 14 to the downstream side, and has a first cylindrical portion 40A that is slightly smaller in diameter than the housing cylinder 30 of the case cylindrical body 28, and a downstream reduced diameter portion from the first cylindrical portion 40A. It has a second cylindrical portion 40B which is continuous downstream through 40C and has a diameter smaller than that of the stepped first cylindrical portion 40A. In the example shown in FIG. 1, the downstream cylinder 40 is reduced in diameter in one step by one downstream-side reduced diameter portion 40 </ b> C, but may be reduced in two or more steps.

  A holding mat 42 is mounted on the outer periphery of the first cylindrical portion 40 </ b> A of the downstream cylinder 40. The downstream cylinder 40 is held by the holding mat 42 in a state of being accommodated inside the case cylinder 28.

  The holding mat 42 is formed in a fiber shape having insulating properties and predetermined elasticity using, for example, alumina mat, resin mat, ceramic wool, interlam mat, mullite, or the like. The holding mat 42 may be the same material as the holding mat 26 or a different material.

  As shown in detail in FIG. 2, the range from the inner peripheral surface of the housing cylinder 30 of the case cylinder 28 to the outer peripheral surface through the inner peripheral surface of the upstream reduced diameter portion 32 (substantially upstream reduced diameter portion). The first glass coat layer 44 is applied to the entire surface 32. In particular, the first glass coat layer 44 is applied to a range that substantially covers the entire surface of the upstream reduced diameter portion 32.

  The first glass coat layer 44 contains an inorganic material such as ceramic, is made of a material having a lower thermal conductivity than the case cylinder 28, and has a predetermined porosity. Furthermore, the first glass coat layer 44 has electrical insulation.

  A second glass coat layer 46 is applied to the entire surface of the downstream cylinder 40. Similarly to the first glass coat layer 44, the second glass coat layer 46 also contains an inorganic substance such as ceramic, and has a predetermined porosity with a material having a lower thermal conductivity than the downstream cylinder 40, and further has an electrical insulating property. have. However, the particle size of the inorganic material of the second glass coat layer 46 is larger than the particle size of the inorganic material of the first glass coat layer 44.

  Next, the operation of the catalytic converter device 12 of this embodiment will be described.

  As shown in FIG. 1, the catalytic converter device 12 is configured so that the case cylinder 28 is concentric with the exhaust pipe 10 in the middle of the exhaust pipe 10 (between the upstream side exhaust pipe 10A and the downstream side exhaust pipe 10B). It is attached. When the exhaust gas passes through the inside of the catalyst carrier 14, substances (hydrocarbons) and the like in the exhaust gas are purified by the catalyst supported on the catalyst carrier 14.

  In the catalytic converter device 12 of the present embodiment, the catalyst carrier 14 is energized by the terminals 18A and 18B and the electrodes 16A and 16B, and the catalyst carrier 14 is heated, whereby the temperature of the catalyst supported on the catalyst carrier 14 is raised and purified. The effect can be exhibited higher. For example, when the temperature of the exhaust gas is low, such as immediately after starting the engine, the catalyst purification performance in the initial stage of engine starting can be ensured by conducting energization heating to the catalyst carrier 14 in advance.

  A first glass coat layer 44 is applied to the inner peripheral surface of the case cylinder 28 to enhance the insulation of the case cylinder 28. Therefore, it is possible to prevent current from leaking to the case cylinder 28 when the catalyst carrier 14 is energized. Thereby, the energization amount to the catalyst carrier 14 can be ensured, and the catalyst carrier 14 can be effectively heated.

  The downstream cylinder 40 is disposed away from the catalyst carrier 14. That is, since the downstream cylinder 40 is not in contact with the catalyst carrier 14, the heat of the catalyst carrier 14 is suppressed from being transmitted to the downstream cylinder 40. Thereby, the temperature fall of the catalyst support 14 by the heat | fever of the catalyst support 14 transmitted to the downstream cylinder 40 can be suppressed.

  Since moisture is contained in the exhaust gas, the moisture in the exhaust pipe 10 may be condensed on the upstream side of the catalytic converter device 12 to form water droplets.

  In the catalytic converter device 12 of the present embodiment, the upstream exhaust pipe 10A and the upstream reduced diameter portion 32 do not overlap in the exhaust flow direction. Therefore, the condensed water in the exhaust passes between the upstream exhaust pipe 10A and the upstream reduced diameter portion 32, and enters the water storage region 36 between the upstream conical member 20 and the connection member 22 and the upstream reduced diameter portion 32. Stored. Since the condensed water is suppressed from adhering to the catalyst carrier 14, the short circuit between the electrodes 16A and 16B due to the condensed water is suppressed. In addition, by suppressing the short circuit, it is possible to secure an energization amount to the catalyst carrier 14 and to effectively raise the temperature of the catalyst carrier 14.

  In particular, in the present embodiment, the upstream reduced diameter portion 32 is integrally extended from the accommodating cylinder 30, and there is no seam between the upstream reduced diameter portion 32 and the accommodating cylinder 30. For this reason, the water accumulated in the water storage region 36 does not enter the catalyst carrier 14 side from the joint between the upstream reduced diameter portion 32 and the housing cylinder 30.

  In addition, since the case cylinder 28 and the upstream reduced diameter portion 32 are configured as a seamless integral member, the case cylinder 28 and the upstream reduced diameter portion 32 are separated. Compared to the structure, the heat capacity is small. Therefore, the amount of heat that moves from the catalyst carrier 14 to the case cylinder 28 and the upstream reduced diameter portion 32 is small, and the temperature of the catalyst carrier 14 can be increased effectively.

  The exhaust may contain carbon, for example, when the engine is cold started. In the catalytic converter device 12 of the present embodiment, the diameter D2 of the upstream end 32S of the upstream reduced diameter portion 32 is larger than the diameter D1 of the downstream end 10T of the upstream exhaust pipe 10A. Therefore, the carbon in the exhaust gas flowing through the upstream side exhaust pipe 10 </ b> A is suppressed from flowing into the water storage region 36. Thereby, since adhesion of carbon to the outer peripheral surface of the upstream reduced diameter portion 32 is suppressed, it is possible to suppress a short circuit between the electrodes 16A and 16B due to the carbon. And the energization amount to the catalyst carrier 14 can be ensured, and the catalyst carrier 14 can be effectively heated.

  Moreover, in the catalytic converter device 12 of the present embodiment, the diameter of the upstream reduced diameter portion 32 is reduced toward the upstream side. As a result, a vortex is generated in the exhaust flowing inside the upstream reduced diameter portion 32, so that the upstream reduced diameter portion 32 generates heat from the exhaust as compared with a non-reduced (cylindrical cylindrical) structure. It becomes easy to receive. Since the temperature of the upstream reduced diameter portion 32 is likely to rise, the combustion of carbon adhering to the upstream reduced diameter portion 32 can be promoted.

  Further, in the catalytic converter device 12 of the present embodiment, the downstream cylinder 40C is also provided with the downstream diameter-reduced portion 40C, so that the downstream cylinder (the cylinder having a constant diameter) is not provided with the downstream diameter-reduced portion 40C. Compared with the shape-like member), the flow velocity of the exhaust gas is increased in the downstream diameter-reduced portion 40C. Thereby, since the temperature of the downstream cylinder 40 is likely to rise, combustion of carbon adhering to the downstream cylinder 40 can be promoted.

  A holding mat 42 is disposed between the downstream cylinder 40 and the case cylinder 28, and the downstream cylinder 40 is not in contact with the case cylinder 28. Therefore, compared to the structure in which the downstream cylinder 40 is in contact with the case cylinder 28, the heat of the downstream cylinder 40 is suppressed from being transmitted to the case cylinder 28. Thereby, the temperature fall of the downstream cylinder 40 by the heat of the downstream cylinder 40 being transmitted to the case cylinder 28 can be suppressed.

  In the catalytic converter device 12 of the present embodiment, since the second glass coat layer 46 is applied to the entire surface of the downstream cylinder 40, adhesion of carbon to the downstream cylinder 40 can be suppressed.

  Moreover, the inorganic particle size of the second glass coat layer 46 is larger than the inorganic particle size of the first glass coat layer 44.

  Here, FIG. 3 shows a process in the middle of assembling the downstream cylinder 40 to the case cylinder 28. A holding mat 42 is attached to the first cylindrical portion 40 </ b> A of the downstream cylinder 40 before being press-fitted into the case cylinder 28. That is, the downstream cylinder 40 with the holding mat 42 mounted thereon is press-fitted into the case cylinder 28 as indicated by an arrow A1.

  Since the inorganic particle size of the second glass coat layer 46 is larger than the inorganic particle size of the first glass coat layer 44, the frictional force acting between the downstream tube 40 and the holding mat 42 is reduced by the case tube 28. And the frictional force acting between the holding mat 42 and the holding mat 42 is larger. For this reason, when the downstream cylinder 40 fitted with the holding mat 42 is press-fitted into the case cylinder 28, the holding mat 42 is slid in the case cylinder 28, and the holding mat 42 is prevented from being displaced from the downstream cylinder 40, Workability of press-fitting work is improved.

DESCRIPTION OF SYMBOLS 10 Exhaust pipe 12 Catalytic converter apparatus 14 Catalyst carrier 28 Case cylinder 30 Cylindrical part (accommodating cylinder)
40 Downstream cylinder 40C Downstream diameter reduced portion 42 Holding mat (downstream cylinder holding member)
44 1st glass coat layer 46 2nd glass coat layer

Claims (1)

A catalyst carrier that carries a catalyst for purifying exhaust gas discharged from the internal combustion engine and is heated by energization;
An accommodating cylinder that is formed in a cylindrical shape and accommodates the catalyst carrier therein and attached to the exhaust pipe;
A downstream cylinder having a downstream diameter-reduced portion that is formed in a cylindrical shape spaced apart from the catalyst carrier on the downstream side in the exhaust flow direction from the catalyst carrier, and whose inner diameter is reduced toward the downstream;
A downstream cylinder holding member disposed between an inner peripheral surface of the storage cylinder and an outer peripheral surface of the downstream cylinder and holding the downstream cylinder in the storage cylinder;
A first glass coat layer provided on the inner peripheral surface of the housing cylinder and containing an inorganic substance;
A second glass coat layer which is provided on the surface of the downstream cylinder and contains an inorganic substance having a particle size larger than the inorganic substance of the first glass coat layer;
A catalytic converter device.

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