Exhaust gas purification devices and gasoline engine-equipped vehicles

Abstract

This invention provides an exhaust gas purification device and a gasoline engine-mounted vehicle, which can ensure the contact area between the honeycomb structure and the exhaust gas, and can accelerate the heating rate of the honeycomb structure. An exhaust gas purification device (5) for a gasoline engine-mounted vehicle (1) is characterized by comprising: a honeycomb structure (6); and a honeycomb filter (7) disposed downstream of the honeycomb structure relative to the flow of exhaust gas (4b). The ratio of the length L1 of the central axis of the honeycomb structure to its diameter D1, L1 / D1, satisfies 0.4 ≤ L1 / D1 ≤ 0.9. The porosity of the partition walls (64) of the honeycomb structure is 40% or more. A three-way catalyst is coated on the partition walls of the honeycomb structure. The opening ratio of the first honeycomb substrate (60) of the honeycomb structure is 85% or more. The cell density of the honeycomb structure is 77.5 cells / cm². 2 The above describes the application of a ternary catalyst to the partition wall (74) of the honeycomb filter, resulting in a cell density of 50 cells / cm². 2 More than 70 per cm 2 the following.

Description

Technical Field

[0001] This utility model relates to an exhaust gas purification device for gasoline engine-equipped vehicles and a gasoline engine-equipped vehicle having the exhaust gas purification device. Background Technology

[0002] As a conventional exhaust gas purification device, the structures described in Patent Documents 1 and 2 are examples. Specifically, in this conventional configuration, a flow-through type honeycomb structure (honeycomb catalyst body) is arranged at the front end of the exhaust gas flow, and a wall-flow type honeycomb filter (sealed honeycomb structure) is arranged at the rear end. A three-way catalyst is supported in the front honeycomb structure, and an oxidation catalyst or a three-way catalyst is supported in the rear honeycomb filter. The three-way catalyst in the honeycomb structure and / or the honeycomb filter is used to purify gaseous components such as NOx, HC, and CO. Furthermore, particulate matter in the exhaust gas is filtered by the honeycomb filter and removed by combustion using an oxidation catalyst or a three-way catalyst.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-169155

[0006] Patent Document 2: Japanese Patent Application Publication No. 2011-167581 Utility Model Content

[0007] The problem to be solved by the utility model

[0008] Patent Document 1 proposes a method of loading an oxidation catalyst onto a honeycomb filter. This oxidation catalyst is specifically designed for the combustion removal of soot and the oxidation of CO and HC. In Patent Document 1, NOx is purified using a three-way catalyst within the front-end honeycomb structure. Therefore, to effectively purify NOx, the volume of the front-end honeycomb structure needs to be increased. However, in this case, the temperature rise of the front-end honeycomb structure takes time, potentially leading to insufficient purification performance during cold starts. Furthermore, this is particularly problematic in electrified vehicles where the engine operates frequently but is not constantly running.

[0009] Patent document 2 adopts the following countermeasures: the downstream honeycomb filter also carries a three-way catalyst, enabling it to purify NOx; the upstream honeycomb structure has a reduced volume to decrease its heat capacity, accelerating the temperature rise during cold start. However, although this can accelerate the heating rate of the honeycomb structure, the reduced volume also decreases the contact area between the honeycomb structure and the exhaust gas, potentially leading to a deterioration in purification performance.

[0010] This invention was made to solve the aforementioned problems. One of its objectives is to provide an exhaust gas purification device and a gasoline engine-mounted vehicle that can ensure the contact area between the honeycomb structure and the exhaust gas, and can accelerate the heating rate of the honeycomb structure. Even when the engine load decreases and the temperature of the exhaust gas drops, the part containing the catalyst can still ensure sufficient heat preservation.

[0011] Solution for solving the problem

[0012] [1] The first aspect of this utility model relates to an exhaust gas purification device, which is an exhaust gas purification device for gasoline engine-equipped vehicles. It is characterized by comprising: a honeycomb structure having a first honeycomb substrate having a porous partition wall dividing a plurality of compartments extending from a first inflow side end face to a first outflow side end face, wherein the compartments of the first honeycomb substrate are open at both ends; and a honeycomb filter having a second honeycomb substrate and a sealing portion, wherein the second honeycomb substrate has a porous partition wall dividing a plurality of compartments extending from a second inflow side end face to a second outflow side end face, and the sealing portion seals the compartments of the second honeycomb substrate at the second inflow side end face or the second outflow side end face, wherein the compartments of the second honeycomb substrate include… A first compartment and a second compartment, the first compartment being open on the second inflow side end face and sealed on the second outflow side end face, the second compartment being open on the second outflow side end face and sealed on the second inflow side end face, the honeycomb filter being disposed downstream of the honeycomb structure relative to the flow of exhaust gas, the ratio of the length L1 of the central axis of the honeycomb structure to its diameter D1, L1 / D1, satisfying 0.4 ≤ L1 / D1 ≤ 0.9, the porosity of the partition walls of the honeycomb structure being 40% or more, a ternary catalyst being coated on the partition walls of the honeycomb structure, the opening ratio of the first honeycomb substrate of the honeycomb structure being 85% or more, and the cell density of the honeycomb structure being 77.5 cells / cm². 2 The honeycomb filter has a ternary catalyst coated on its partition walls, and the cell density of the honeycomb filter is 50 cells / cm³. 2 More than 70 per cm 2 the following.

[0013] [2] The second item of this utility model may also relate to the exhaust gas purification device described in the first item, characterized in that the porosity of the partition wall of the honeycomb filter is more than 50%.

[0014] [3] The third item of this utility model may also relate to the exhaust gas purification device described in the first item, characterized in that the gasoline engine-equipped vehicle is a range extender electric vehicle with a gasoline engine, which serves as a range extender for the purpose of charging the battery.

[0015] [4] The fourth item of this utility model may also relate to the exhaust gas purification device described in the first item, characterized in that the thickness of the partition wall of the honeycomb filter is more than 0.102 mm and less than 0.170 mm.

[0016] [5] The fifth item of this utility model may also relate to the exhaust gas purification device described in the first item, characterized in that the ratio of the length L2 of the honeycomb filter in the central axis direction to the diameter D2, L2 / D2, satisfies 0.6≤L2 / D2≤0.9.

[0017] [6] The sixth item of this utility model may also relate to the exhaust gas purification device described in the first item, characterized in that it further comprises an exhaust gas sensor, which detects the oxygen concentration or NOx concentration of the exhaust gas, and a groove or hole extending radially inward from the outer peripheral surface is provided on the first honeycomb substrate, and the exhaust gas sensor is inserted into the groove or hole.

[0018] [7] The seventh item of this utility model may also relate to the waste gas purification device described in the first item, characterized in that the porosity of the partition wall of the honeycomb structure is less than 55%.

[0019] [8] The eighth item of this utility model may also relate to the waste gas purification device described in the first item, characterized in that the opening ratio of the first honeycomb substrate of the honeycomb structure is less than 92%.

[0020] [9] Item 9 of this utility model may also relate to the waste gas purification device described in item 1, characterized in that the cell density of the honeycomb structure is 140 cells / cm². 2 the following.

[0021]

[10] The 10th item of this utility model relates to a gasoline engine-equipped vehicle, characterized in that it has an exhaust gas purification device as described in any one of items 1 to 9.

[0022] Utility Model Effect

[0023] According to one embodiment of the exhaust gas purification device and gasoline engine-mounted vehicle of this utility model, the ratio L1 of the length L1 along the central axis of the honeycomb structure to its diameter D1, L1 / D1, satisfies 0.4 ≤ L1 / D1 ≤ 0.9; the porosity of the partition walls of the honeycomb structure is 40% or more; a three-way catalyst is coated on the partition walls of the honeycomb structure; the opening ratio of the first honeycomb substrate of the honeycomb structure is 85% or more; and the cell density of the honeycomb structure is 77.5 cells / cm³. 2 The honeycomb filter has a ternary catalyst coated on its partition walls, and the cell density is 50 cells / cm³. 2 More than 70 per cm 2Therefore, it is possible to ensure the contact area between the honeycomb structure and the exhaust gas, and to accelerate the heating rate of the honeycomb structure. Even when the engine load decreases and the temperature of the exhaust gas drops, it is possible to ensure that the part where the catalyst is located maintains sufficient temperature insulation. Attached Figure Description

[0024] Figure 1 This is an explanatory diagram showing a gasoline engine-equipped vehicle according to an embodiment of the present invention.

[0025] Figure 2 yes Figure 1 A cross-sectional view of the exhaust gas purification device.

[0026] Figure 3 It means Figure 2 The front view of the first inflow side end face of the honeycomb structure.

[0027] Figure 4 It means Figure 2 A three-dimensional diagram of a honeycomb structure.

[0028] Figure 5 It means Figure 2 The front view of the second inflow side end face of the cellular filter.

[0029] Figure 6 It means Figure 2 A 3D view of a honeycomb filter.

[0030] Figure 7 yes Figure 2 A cross-sectional view of a modified example of an exhaust gas purification device.

[0031] Figure 8 It means Figure 7 A three-dimensional diagram of a honeycomb structure. Detailed Implementation

[0032] Hereinafter, embodiments for implementing this utility model will be described with reference to the accompanying drawings. This utility model is not limited to any particular embodiment, and can be embodied by modifying the constituent elements without departing from its spirit. Furthermore, various utility models can be formed by appropriately combining the multiple constituent elements disclosed in each embodiment. For example, several constituent elements may be deleted from all the constituent elements shown in the embodiments. Moreover, constituent elements from different embodiments may be appropriately combined.

[0033] <About Gasoline Engine Vehicles>

[0034] Figure 1 This is an explanatory diagram showing a gasoline engine-equipped vehicle 1 according to an embodiment of the present invention. (See diagram below.) Figure 1As shown, the gasoline engine-equipped vehicle 1 of this embodiment includes a motor 2, a battery 3, a gasoline engine 4, and an exhaust gas purification device 5.

[0035] Motor 2 is a power source for driving. That is, the output shaft of motor 2 is connected to wheel 1a, and the output of motor 2 can drive wheel 1a, thus enabling the gasoline engine to propel vehicle 1. Battery 3 is connected to motor 2. Motor 2 can operate using electricity stored in battery 3. Motor 2 can be configured to perform regenerative braking, storing the electricity generated by motor 2 in battery 3.

[0036] The gasoline engine 4 is an internal combustion engine that uses gasoline as fuel and is used as a power source for driving and / or generating electricity. When the gasoline engine 4 is used as a power source for driving, its output shaft is connected to the wheel 1a, and the output of the gasoline engine 4 drives the wheel 1a, thus enabling the gasoline engine to carry the vehicle 1. When the gasoline engine 4 is used as a power source for generating electricity, its output shaft is connected to a generator, and the output of the gasoline engine 4 drives the generator. The generator can be a motor 2, or it can be separate from the motor 2. The gasoline engine 4 can be used solely as a power source for driving, or it can be used solely as a power source for generating electricity.

[0037] The gasoline engine-equipped vehicle 1 in this embodiment is sometimes referred to as a hybrid vehicle. Hybrid vehicles also include, for example, plug-in hybrid vehicles that can connect an external power source, such as a commercial power system, to the battery 3. Alternatively, the gasoline engine-equipped vehicle 1 can also be a range-extender electric vehicle (EV) having a gasoline engine 4 that functions as a range extender for charging the battery 3. In other words, when the gasoline engine 4 is used solely as a power source for electricity generation, it is referred to as a range extender. In a range-extender electric vehicle, when the charging rate of the battery 3 decreases, electricity is generated by the gasoline engine 4, thereby extending the driving range of the motor 2 and the battery 3. Furthermore, the motor 2 and battery 3 can be omitted from the gasoline engine-equipped vehicle 1.

[0038] An exhaust gas purification device 5 is installed in the exhaust system 4a of the gasoline engine 4 to purify the exhaust gas 4b from the gasoline engine 4. The purification of exhaust gas 4b includes the purification of gaseous components such as NOx, HC, and CO by a catalyst, as well as the removal of particulate matter generated by the combustion of lubricating oil and fuel. The particulate matter includes lubricating oil and ash from the fuel.

[0039] <About exhaust gas purification devices>

[0040] Next, Figure 2 yes Figure 1 A cross-sectional view of the exhaust gas purification device 5. Figure 3 It means Figure 2 The front view of the first inflow side end face 61 of the honeycomb structure 6. Figure 4 It means Figure 2A three-dimensional view of the honeycomb structure 6. Figure 5 It means Figure 2 The front view of the second inflow side end face 71 of the cellular filter 7. Figure 6 It means Figure 2 A 3D view of the honeycomb filter 7.

[0041] like Figure 2 As shown, the exhaust gas purification device 5 has a honeycomb structure 6 and a honeycomb filter 7.

[0042] The honeycomb structure 6 has a first honeycomb substrate 60. The first honeycomb substrate 60 has porous partitions 64 that divide and form a plurality of compartments 63 extending from a first inflow side end face 61 to a first outflow side end face 62. The compartments 63 of the first honeycomb substrate 60 are open at both ends. The honeycomb structure 6 is flow-through type. That is, exhaust gas 4b from the first inflow side end face 61 passes through the compartments 63 and is discharged from the first outflow side end face 62.

[0043] The honeycomb filter 7 has a second honeycomb substrate 70 and a sealing portion 75. The second honeycomb substrate 70 has a porous partition wall 74 dividing a plurality of compartments 73 extending from a second inflow side end face 71 to a second outflow side end face 72. The sealing portion 75 seals the compartments 73 of the second honeycomb substrate 70 using either the second inflow side end face 71 or the second outflow side end face 72. The compartments 73 of the second honeycomb substrate 70 include: a first compartment 731 that is open on the second inflow side end face 71 and sealed on the second outflow side end face 72, and a second compartment 732 that is open on the second outflow side end face 72 and sealed on the second inflow side end face 71. The honeycomb filter 7 is a wall-flow type. That is, exhaust gas 4b from the second inflow side end face 71 enters the first compartment 731, passes through the partition wall 74 between the first compartment 731 and the second compartment 732, enters the second compartment 732, and exits from the second outflow side end face 72. As exhaust gas 4b passes through partition 74, the particulate matter contained in exhaust gas 4b is captured within the honeycomb filter 7. That is, the honeycomb filter 7 at least removes particulate matter, thus purifying exhaust gas 4b. The honeycomb filter 7 is positioned downstream of the honeycomb structure 6 in the exhaust system 4a of the gasoline engine-equipped vehicle 1 relative to the flow of exhaust gas 4b.

[0044] The honeycomb structure 6 and the honeycomb filter 7 can be housed in the tank 90. ​​The honeycomb structure 6 and the honeycomb filter 7 are respectively disposed within the tank 90 with their outer peripheries covered by a liner 95 (cushioning material). This liner 95 prevents damage to the honeycomb structure 6 and the honeycomb filter 7. Preferably, the honeycomb structure 6 and the honeycomb filter 7 are housed within the tank 90 under pressure applied from the outside via the liner 95. Housed in this manner, movement of the honeycomb structure 6 and the honeycomb filter 7 within the tank 90 is prevented, ensuring their stability within the tank 90. ​​The liner 95 can be made of ceramic fiber or similar materials.

[0045] In the exhaust gas purification device 5 of this embodiment, the ratio L1 of the length L1 in the central axis direction of the honeycomb structure 6 to its diameter D1, L1 / D1, satisfies 0.4 ≤ L1 / D1 ≤ 0.9; the porosity of the partition wall 64 of the honeycomb structure 6 is 40% or more; a ternary catalyst is coated on the partition wall 64 of the honeycomb structure 6; the opening ratio of the first honeycomb substrate 60 of the honeycomb structure 6 is 85% or more; and the cell density of the honeycomb structure 6 is 77.5 cells / cm³. 2 In addition, a three-way catalyst is coated on the partition wall 74 of the honeycomb filter 7, and the cell density of the honeycomb filter 7 is 50 cells / cm³. 2 More than 70 per cm 2 The following conditions are met to ensure the contact area between the honeycomb structure 6 and the exhaust gas 4b, and to accelerate the heating rate of the honeycomb structure 6. Even when the engine load decreases and the temperature of the exhaust gas 4b drops, the part containing the catalyst can still maintain sufficient temperature insulation.

[0046] The ratio L1 / D1 is an indicator of the degree to which the length L1 of the honeycomb structure 6 is relative to the diameter D1 along its central axis. A larger ratio L1 / D1 allows for a longer residence time of the exhaust gas 4b within the honeycomb structure 6 (increasing the contact area between the partition wall 64 and the exhaust gas 4b), and thus a longer contact time between the catalyst and the gas, facilitating the catalytic reaction. However, a large L1 / D1 results in a slower heating rate of the honeycomb structure 6 due to the increased heat capacity. In the exhaust gas purification device 5 of this embodiment, the porosity of the partition wall 64 of the honeycomb structure 6 is set to 40% or more, the opening ratio of the first honeycomb substrate 60 of the honeycomb structure 6 is set to 85% or more, and the cell density of the honeycomb structure 6 is set to 77.5 cells / cm². 2 The above measures reduce the weight per unit volume of the honeycomb structure 6, suppressing the increase in heat capacity even within the range of 0.4 ≤ L1 / D1 ≤ 0.9, and accelerating the heating rate of the honeycomb structure 6. Furthermore, by setting the cell density of the honeycomb filter 7 to 50 cells / cm³... 2 More than 70 per cm 2The following (i.e., a cell density less than that of the honeycomb structure 6) increases the heat capacity of the honeycomb filter 7 compared to the honeycomb structure 6, making it easier to maintain the temperature of the honeycomb filter 7 even when the engine load decreases and the exhaust gas temperature drops. By maintaining the temperature of the honeycomb filter 7, the purification performance can be maintained even when the temperature of the exhaust gas 4b decreases, thanks to the three-way catalyst supported on the honeycomb filter 7.

[0047] By coating the partition wall 74 of the honeycomb filter 7 with a three-way catalyst, NOx, HC, and CO can be purified in the honeycomb filter 7 as well as for the exhaust gas 4b. In particular, during the period when the exhaust gas 4b gradually decreases in temperature, the temperature of the upstream honeycomb structure 6 decreases, and the catalyst in the honeycomb structure 6 loses its purification performance, the honeycomb filter 7, with its large heat capacity, can maintain its temperature. Therefore, the purification performance of NOx, HC, CO, and other gaseous components can be maintained by the three-way catalyst supported on the honeycomb filter 7.

[0048] The diameter D1 of the honeycomb structure 6 is defined as the length of a line segment passing through the central axis in a plane orthogonal to the central axis, with both ends located on the outer edge of the honeycomb structure 6, and is measured using a laser length measuring instrument. The length L1 of the honeycomb structure 6 in the direction of the central axis is defined as the distance between the first inflow side end face 61 and the first outflow side end face 62 in the direction of extension of the compartment 63, and is measured using a laser length measuring instrument.

[0049] The porosity of the partition wall 64 is measured using a mercury porosity meter. The porosity of the partition wall 64 of the honeycomb structure 6 is preferably 55% or less. By setting it to 55% or less, the possibility of the honeycomb structure 6 becoming brittle and easily detaching can be reduced.

[0050] The aperture ratio of the first honeycomb substrate 60 is defined as the ratio of the area of ​​the compartment 63 to the total area of ​​the cross-section of the first honeycomb substrate 60 orthogonal to the axial direction at the axial center position of the first honeycomb substrate 60. The total area of ​​the cross-section of the first honeycomb substrate 60 orthogonal to the axial direction is determined based on the shape of the first honeycomb substrate 60, ignoring the presence of the compartment 63. The area of ​​the compartment 63 is determined based on the shape of the partition wall 64, ignoring the presence of the catalyst supported on the partition wall 64. The aperture ratio is measured by image analysis of the cross-section of the first honeycomb substrate 60. The aperture ratio is preferably 92% or less. By being 92% or less, the possibility of the honeycomb structure 6 becoming brittle and easily falling off can be reduced.

[0051] The cell density of the honeycomb structure 6 is defined as the number of cells 63 per unit area in a cross-section orthogonal to the central axis of the first honeycomb substrate 60, and is measured by image analysis of this cross-section. The preferred cell density of the honeycomb structure 6 is 140 cells / cm². 2 The following is a sample size: 140 pieces / cm. 2The following measures can reduce the likelihood of the honeycomb structure 6 becoming brittle and easily falling off.

[0052] A three-way catalyst is a catalyst that primarily purifies hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). Examples include catalysts containing platinum (Pt), palladium (Pd), and rhodium (Rh). Through this three-way catalyst, hydrocarbons are oxidized or reduced to water and carbon dioxide, carbon monoxide is oxidized or reduced to carbon dioxide, and nitrogen oxides are oxidized or reduced to nitrogen. By supporting the catalyst in partition wall 64, the honeycomb structure 6 purifies gaseous components such as NOx, HC, and CO, thus purifying exhaust gas 4b.

[0053] The cell density of the cellular filter 7 is defined as the number of cells 73 per unit area in a cross section orthogonal to the central axis of the second cellular substrate 70, and is measured by image analysis of this cross section.

[0054] The porosity of the septum 74 in the honeycomb filter 7 is preferably 50% or more. The porosity of the septum 74 is a value measured by a mercury porosity meter. By ensuring that the porosity is 50% or more, clogging when carrying the catalyst can be prevented.

[0055] More preferably, the porosity of the partition wall 74 is 60% or more. More preferably, the porosity of the partition wall 74 is 65% or less. With a porosity of 65% or less, the strength of the honeycomb filter 7 can be ensured, the liner surface pressure can be sufficiently applied when it is held in the tank 90 by the liner surface pressure, and the detachment from the tank 90 caused by gas pressure or vibration can be prevented.

[0056] The thickness of the partition wall 74 in the honeycomb filter 7 is preferably 0.102 mm or more and 0.170 mm or less. The thickness of the partition wall 74 is measured by microscopic observation of a cross-section parallel to the central axis. A partition wall thickness of 0.102 mm or more maintains particle capture efficiency, prevents clogging during catalyst loading, and maintains the strength of the honeycomb filter. A partition wall thickness of 0.170 mm or less increases the honeycomb opening ratio, ensuring ash accumulation capacity and preventing excessive filter pressure loss due to reduced pressure loss through the partition walls.

[0057] The ratio L2 of the length L2 along the central axis of the honeycomb filter 7 to its diameter D2, L2 / D2, preferably satisfies 0.6 ≤ L2 / D2 ≤ 0.9. The diameter D2 of the honeycomb filter 7 is defined as the length of a line segment passing through the central axis in a plane orthogonal to the central axis, with both ends located on the outer edges of the honeycomb filter 7, and is measured using a laser length measuring instrument. The length L2 along the central axis of the honeycomb filter 7 is defined as the distance between the second inflow-side end face 71 and the second outflow-side end face 72 in the direction in which the compartment 73 extends, and is also measured using a laser length measuring instrument. By ensuring 0.6 ≤ L2 / D2 ≤ 0.9, it is possible to suppress the installation length required for proper mounting while sufficiently ensuring the volume of the honeycomb filter 7.

[0058] Next, Figure 7 yes Figure 2 A cross-sectional view of a modified example of the exhaust gas purification device 5. Figure 8 It means Figure 7 A three-dimensional diagram of the honeycomb structure 6. (See diagram below.) Figure 7 As shown, the exhaust gas purification device 5 may also include an exhaust gas sensor 8 for detecting the oxygen concentration or NOx concentration of the exhaust gas 4b. A groove 65 extending radially inward from the outer peripheral surface can be provided on the first honeycomb substrate 60 of the honeycomb structure 6, through which the exhaust gas sensor 8 can be inserted. With this configuration, it is unnecessary to ensure space between the honeycomb structure 6 and the honeycomb filter 7 for mounting the exhaust gas sensor 8, thus reducing the distance between the honeycomb structure 6 and the honeycomb filter 7 and consequently reducing the space required for mounting.

[0059] The exhaust gas sensor 8 can be a strip-shaped component, and its front end may have an element for measuring the oxygen concentration or NOx concentration of the exhaust gas 4b. Examples of such an exhaust gas sensor 8 include, for instance, the automotive oxygen sensor manufactured by Niterra.

[0060] A hole 90a is provided on the peripheral wall of the tank 90, and the front end of the exhaust gas sensor 8 is inserted into the tank 90 from the outside through the hole 90a. The front end of the exhaust gas sensor 8 is inserted into the groove 65 of the first honeycomb substrate 60.

[0061] The slot 65 can extend from either the first inflow-side end face 61 or the first outflow-side end face 62 of the first honeycomb substrate 60 along the direction extending from the compartment 63. In the illustrated embodiment, the slot 65 extends from the first outflow-side end face 62. The length of the slot 65 in the direction extending from the compartment 63 can be 1 / 10 to 1 / 3 of the length L1 in the direction of the central axis of the honeycomb structure 6. By giving the slot 65 such a length, space for mounting the gas sensor can be ensured. The depth of the slot 65 on the radially inner side of the first honeycomb substrate 60 can be 1 / 5 to 1 / 3 of the diameter of the first honeycomb substrate 60. By giving the slot 65 such a depth, the detection part of the sensor can be positioned appropriately. Although not illustrated, instead of the slot 65, a hole extending radially inward from the outer peripheral surface can be provided in the first honeycomb substrate 60 of the honeycomb structure 6. The diameter of this hole can be set to a degree that allows the front end of the exhaust gas sensor 8 to be inserted.

[0062] The following provides a more detailed description of the honeycomb structure 6 and the honeycomb filter 7.

[0063] <About honeycomb structures>

[0064] like Figure 2 As shown, in the honeycomb structure 6 (first honeycomb substrate 60), the first honeycomb substrate 60 has a honeycomb shape with porous partitions 64, which divide the honeycomb structure 6 into multiple compartments 63 that extend from the first inflow side end face 61 to the first outflow side end face 62, forming a flow path for the fluid. The compartments 63 formed in the honeycomb structure 6 ensure the flow path of the fluid from the first inflow side end face 61 to the first outflow side end face 62 (the compartments 63 are not sealed). Therefore, even if a large amount of three-way catalyst is loaded in the partitions 64 of the honeycomb structure 6, it is difficult to impede the flow of the fluid (exhaust gas 4b), and the increase in pressure loss is small. Therefore, it is possible to increase the loading of the three-way catalyst per unit volume. It should be noted that in the honeycomb structure 6, the loading of the three-way catalyst per unit volume can be uniform, but it is preferable that the loading of the three-way catalyst per unit volume at the end on the first inflow side end face 61 side is greater than the loading of the three-way catalyst at other parts. On the other hand, if the loading per unit volume of the three-way catalyst on the end of the first inflow side face 61 is less than the loading per unit volume of the three-way catalyst on other parts, the heat generated by the catalytic reaction at the end of the fluid inflow side (the end of the first inflow side face 61) is insufficient, thus the heating rate decreases. Therefore, time is spent before reaching the catalyst's active temperature, and the purification performance of exhaust gas 4b may become insufficient. If the loading per unit volume of the three-way catalyst is greater than the loading per unit volume of the three-way catalyst on other parts, the heat generated by the catalytic reaction at the end of the first inflow side face 61 is increased compared to other parts, thus enabling a larger amount of the three-way catalyst to reach the catalyst active temperature earlier after engine start-up. Figure 3 It is a schematic representation Figure 2 The diagram shows a top view of the first inflow side end face 61 of the honeycomb structure 6. The end of the first inflow side end face 61 is located in the range from the first inflow side end face 61 to a position that is 10% to 60% of the length of the honeycomb structure 6 along its central axis.

[0065] The shape of the honeycomb structure 6 is not limited to Figure 4 The cylindrical shape shown can be exemplified by elliptical cylindrical shapes, quadrangular cylindrical shapes, and cylindrical shapes with polygonal bases, as well as cylindrical shapes with irregular bases.

[0066] Specifically, the honeycomb structure 6 is preferably 30 to 200 mm in length along its central axis.

[0067] The diameter of the honeycomb structure 6 can be the same as or smaller than the diameter of the honeycomb filter 7. Preferably, the diameter of the honeycomb structure 6 is smaller than the diameter of the honeycomb filter 7. When the diameter of the honeycomb structure 6 is smaller than the diameter of the honeycomb filter 7, the honeycomb structure 6 becomes lighter than the honeycomb filter 7, provided that the length of the honeycomb structure 6 along its central axis is the same as or shorter than the length of the honeycomb structure 6 along its central axis. Therefore, the heating rate is faster, and the honeycomb structure 6 can easily reach the catalyst activation temperature in the early stages after engine start-up. Here, since there is a limit to increasing the volume of the canister 90, reducing the size of the honeycomb structure 6 allows for a larger honeycomb filter 7. Moreover, if the honeycomb filter 7 is larger, it can efficiently remove particulate matter from the exhaust gas 4b.

[0068] When the diameter of the honeycomb structure 6 is smaller than the diameter of the honeycomb filter 7, the diameter of the honeycomb structure 6 is preferably 50% to 80% of the diameter of the honeycomb filter 7, more preferably 55% to 75%, and even more preferably 60% to 70%. By setting the diameter within the above range, the honeycomb structure 6 can be heated at a better rate using the heat of the exhaust gas 4b. However, if the diameter is less than 50%, the pressure drop may become too large. On the other hand, if it exceeds 80%, the honeycomb structure 6 may not heat up sufficiently due to the heat of the exhaust gas 4b (the heating rate becomes slower). Furthermore, for example, when the honeycomb structure 6 is cylindrical, the diameter of its bottom surface is preferably 80 mm to 180 mm. When the shape of the honeycomb structure 6 is other than cylindrical, the area of ​​its bottom surface is preferably in the same range as the area of ​​the bottom surface in the cylindrical case described above.

[0069] The thickness of the partition wall 64 is preferably 50.8–101.6 μm, more preferably 50.8–75 μm, and particularly preferably 65–75 μm. If it is less than 50.8 μm, the strength of the honeycomb structure 6 may decrease. On the other hand, if it exceeds 101.6 μm, the pressure loss when the exhaust gas 4b passes through the compartment 63 may increase. The thickness of the partition wall 64 is determined by microscopic observation of a cross-section parallel to the central axis.

[0070] The cell density of the honeycomb structure 6 (i.e., the cell density of the cross section orthogonal to the central axis of the first honeycomb substrate 60) can be greater than the cell density of the second honeycomb substrate 70. Furthermore, the aperture ratio of the first honeycomb substrate 60 of the honeycomb structure 6 can be greater than the aperture ratio of the second honeycomb substrate 70 of the honeycomb filter 7. With such a larger cell density and aperture ratio, the partition walls 64 of the honeycomb structure 6 are thinner than the partition walls 74 of the honeycomb filter 7. Therefore, when the honeycomb structure 6 and the honeycomb filter 7 have the same volume, or when the volume of the honeycomb structure 6 is smaller than that of the honeycomb filter 7, the honeycomb structure 6 is lighter than the honeycomb filter 7. Thus, in the early stages after engine startup, the honeycomb structure 6 easily reaches the catalyst activation temperature. It should be noted that the aperture ratio of the second honeycomb substrate 70 is defined by the ratio of the area of ​​the cell 73 to the total area of ​​the cross section of the second honeycomb substrate 70 orthogonal to the axial center position. The aperture ratio is calculated independently of the sealing portion 75. The total area of ​​the cross-section of the second honeycomb substrate 70, orthogonal to the axial direction, is determined by the shape of the second honeycomb substrate 70, ignoring the presence of the compartments 73. The area of ​​the compartments 73 is determined by the shape of the compartments 74, ignoring the presence of the catalyst supported on the partition walls 74. The aperture ratio is measured by image analysis of the cross-section of the second honeycomb substrate 70.

[0071] The opening ratio of the first honeycomb substrate 60 of the honeycomb structure 6 can be greater than that of the second honeycomb substrate 70 of the honeycomb filter 7. However, in this case, it is preferable that the porosity of the partition wall 64 of the first honeycomb substrate 60 is less than that of the partition wall 74 of the second honeycomb substrate 70. If the porosity of the partition wall 64 is less than that of the partition wall 74, the strength of the honeycomb structure 6 can be ensured. That is, when the opening ratio of the first honeycomb substrate 60 of the honeycomb structure 6 is greater than that of the second honeycomb substrate 70 of the honeycomb filter 7, the heat capacity of the honeycomb structure 6 is less than that of the honeycomb filter 7, and therefore the honeycomb structure 6 heats up faster than the honeycomb filter 7. However, the strength of the honeycomb structure 6 may become insufficient. Therefore, the porosity of the partition wall 64 is preferably less than that of the partition wall 74. Furthermore, since the honeycomb structure 6 heats up in the early stage, the heat from the exhaust gas 4b can be used to heat up the honeycomb structure 6. That is, the honeycomb filter 7 can be heated up rapidly.

[0072] The average pore size of the partition wall 64 is preferably 5 to 30 μm, more preferably 10 to 25 μm. If it is less than 5 μm, sufficient adhesion between the catalyst layer and the surface of the partition wall 64 cannot be achieved when forming a catalyst layer by supporting the ternary catalyst on the partition wall 64, and the catalyst layer may peel off. On the other hand, if it exceeds 30 μm, the honeycomb structure 6 may become brittle and easily detach. The average pore size of the partition wall 64 is a value measured with a mercury porosity meter.

[0073] The shape of the compartments 63 in the honeycomb structure 6 is not particularly limited. In a cross-section orthogonal to the central axis, the preferred shapes are polygons such as triangles, quadrilaterals, pentagons, hexagons, and octagons, circles, or ellipses, but other irregular shapes are also acceptable. A combination of quadrilaterals and octagons is also a preferred option.

[0074] Furthermore, the hydraulic diameters of all compartments in the honeycomb structure 6 can be the same, and the hydraulic diameters of the compartment 63 opening at the first inflow side end face 61 and the compartment 63 opening at the first outflow side end face 62 can also be different. Any of the above is acceptable, but it is preferred that the hydraulic diameters are different. Specifically, in the case of purifying the exhaust gas 4b of the gasoline engine, in order to reduce pressure loss, it is preferable that the hydraulic diameter of the compartment 63 opening at the first outflow side end face 62 is larger than the hydraulic diameter of the compartment 63 opening at the first inflow side end face 61, and preferably that the hydraulic diameter of the compartment 63 opening at the first inflow side end face 61 is 20% to 45% of the hydraulic diameter of the compartment 63 opening at the first outflow side end face 62. In this specification, the "hydraulic diameter of the compartment" is a value calculated using the formula "4 × (cross-sectional area) / (perimeter)". Here, "cross-sectional area" refers to the area of ​​the compartment in a section orthogonal to the direction in which the compartment extends, and "perimeter" refers to the "length of the outer perimeter of the compartment" in a section orthogonal to the direction in which the compartment extends.

[0075] The partitions 64 of the honeycomb structure 6 are primarily composed of ceramic. Specifically, the material of the partitions 64 is preferably selected from at least one group selected from silicon carbide, silicon-silicon carbide composite materials, cordierite, mullite, alumina, spinel, silicon carbide-cordierite composite materials, lithium aluminum silicate, and aluminum titanate. Cordierite, with its low coefficient of thermal expansion and excellent thermal shock resistance, is particularly preferred. Furthermore, "primarily composed of ceramic" means that the entire structure contains at least 90% ceramic by mass.

[0076] Furthermore, the honeycomb structure 6 may have an outer peripheral wall located at its outermost periphery. It should be noted that the outer peripheral wall is preferably a molded integral wall formed integrally with the porous substrate during molding, but after molding, the outer periphery of the porous substrate is ground to form a predetermined shape; a cement-coated wall with an outer peripheral wall made of ceramic cement or the like is also preferred. In the case of a molded integral wall, the material of the outer peripheral wall is preferably the same as the material of the honeycomb structure 6. Alternatively, if the outer peripheral wall is a cement-coated wall, materials containing flux components such as glass added to the matrix can be used as materials for the cement-coated wall. Furthermore, the thickness of the outer peripheral wall is preferably 0.5 to 1.5 mm.

[0077] The loading of the three-way catalyst per unit volume supported on the honeycomb structure 6 is preferably 200–400 g / L, more preferably 200–300 g / L, and particularly preferably 200–250 g / L. If the loading is less than 200 g / L, the amount of three-way catalyst is too small, resulting in insufficient heat generated by the catalytic reaction, which may make it difficult to heat up to the active temperature of the three-way catalyst in the early stages after engine startup. If it exceeds 400 g / L, the loading per unit volume is too large, narrowing the flow path of the compartment 63 with openings at both ends, which may increase pressure loss.

[0078] <About Cellular Filters>

[0079] like Figure 2 As shown, in the honeycomb filter 7, the second honeycomb substrate 70 has a honeycomb shape with porous partitions 74, which divides into a plurality of compartments 73 that form a flow path for fluid from the second inflow side end face 71 to the second outflow side end face 72. Figure 5 This is a schematic top view showing the second inflow side end face 71 of the honeycomb filter 7. The shape of the honeycomb filter 7 is not limited to... Figure 6 The cylindrical shape shown can be exemplified by elliptical cylindrical shapes, quadrangular cylindrical shapes, and cylindrical shapes with polygonal bases, as well as cylindrical shapes with irregular bases.

[0080] Furthermore, the size of the honeycomb filter 7 is preferably such that its length along the central axis is 50 to 200 mm. Additionally, for example, when the honeycomb filter 7 is cylindrical, its bottom diameter is preferably 80 to 180 mm. When the honeycomb filter 7 is not cylindrical, its bottom area is preferably within the same range as the bottom area in the cylindrical case described above.

[0081] The average pore size of the partition wall 74 is preferably 7 μm to 40 μm, more preferably 8 μm to 35 μm. If it is less than 7 μm, the pressure loss may increase even when there is little accumulation of particulate matter. On the other hand, if it exceeds 40 μm, the honeycomb filter 7 may become brittle and easily detach, or the collection performance of particulate matter may decrease. The average pore size of the partition wall 74 is a value measured by a mercury porosity meter.

[0082] The shape of the compartments 73 in the honeycomb filter 7 is not particularly limited. In a cross-section orthogonal to the central axis, it is preferably a polygon, circle, or ellipse, such as a triangle, quadrilateral, pentagon, hexagon, or octagon, or other irregular shape. A combination of quadrilaterals and octagons is also preferred. Furthermore, it is preferable that in a cross-section orthogonal to the direction in which the compartments 73 extend, all compartments 73 have the same cross-sectional area, but the cross-sectional area of ​​the second compartment 732 with the sealing portion 75 on the second inflow side end face 71 (the cross-sectional area in the cross-section orthogonal to the direction in which the compartments 73 extend) is smaller than the cross-sectional area of ​​the first compartment 731 with the sealing portion 75 on the second outflow side end face 72 (the cross-sectional area in the cross-section orthogonal to the direction in which the compartments 73 extend). If this is the case, the increase in pressure loss when capturing particulate matter in the exhaust gas 4b can be suppressed.

[0083] Furthermore, the hydraulic diameters of all compartments in the second honeycomb substrate 70 can be identical, and the hydraulic diameters of the first compartment 731 and the second compartment 732 can also be different, but it is preferable that the hydraulic diameters are different. Specifically, in the case of purifying the exhaust gas 4b of a gasoline engine, in order to reduce pressure loss, it is preferable that the hydraulic diameter of the second compartment 732 is larger than that of the first compartment 731, and the hydraulic diameter of the first compartment 731 is preferably 20% to 45% of the hydraulic diameter of the second compartment 732.

[0084] Furthermore, the honeycomb filter 7 may have an outer peripheral wall located at its outermost periphery. It should be noted that the outer peripheral wall is preferably a molded integral wall formed integrally with the porous substrate during molding, but after molding, the outer periphery of the porous substrate is ground to form a predetermined shape; a cement-coated wall with the outer peripheral wall formed of ceramic cement or the like is also preferred. In the case of a molded integral wall, the material of the outer peripheral wall is preferably the same as the material of the honeycomb filter 7. Alternatively, if the outer peripheral wall is a cement-coated wall, materials containing flux components such as glass added to the matrix can be used as materials for the cement-coated wall. Furthermore, the thickness of the outer peripheral wall is preferably 0.5 to 1.5 mm.

[0085] The catalyst loading per unit volume in the honeycomb filter 7 can be less than the three-way catalyst loading per unit volume in the partitions 64 of the honeycomb structure 6. By adjusting the catalyst loading per unit volume in this way, the heat generated by the catalytic reaction can be increased. That is, even with the minimum amount of catalyst (including the three-way catalyst) required for the purification of exhaust gas 4b, the catalyst (including the three-way catalyst) can be uniformly loaded in the honeycomb filter 7 and the honeycomb structure 6. However, when the ratio of the three-way catalyst loaded in the partitions 64 of the honeycomb structure 6 is increased, the heat generated by the catalytic reaction increases, and therefore the heating rate of the honeycomb structure 6 increases. Therefore, in the early stage after engine start-up, that is, in the short time after the engine just starts running, the catalyst (including the three-way catalyst) easily reaches the activation temperature. Furthermore, the heat from the exhaust gas 4b heated by the honeycomb structure 6 can also be used to heat the honeycomb structure 6.

[0086] Specifically, the catalyst loading per unit volume in the honeycomb filter 7 is preferably 160 g / L or less, more preferably 10 to 120 g / L, and particularly preferably 20 to 100 g / L. If the loading exceeds 160 g / L, the pores formed in the partition wall 74 will be blocked by the catalyst, and the pressure loss may become too large.

[0087] The sealing portion 75 disposed in the honeycomb filter 7 can be made of a sealing material comprising ceramic raw material, water or alcohol, and organic binder. Preferably, the ceramic raw material is the same as that used as the raw material for the second honeycomb substrate 70 (the partition wall 74 of the second honeycomb substrate 70). Thus, during firing, the sealing portion 75 is firmly bonded to the partition wall 74.

[0088] The sealing section 75 is preferably configured to alternately seal the first compartment 731 and the second compartment 732, and the two end faces are in a checkered pattern.

[0089] The depth of the sealing portion 75 is preferably 1 to 5 mm, more preferably 1 to 3 mm. If it is shallower than 1 mm, the strength of the sealing portion 75 may be reduced. On the other hand, if it is deeper than 5 mm, the PM capture area of ​​the partition wall 74 may be smaller. Here, the depth of the sealing portion 75 refers to the length of the sealing portion 75 in the direction extending from the compartment 73.

[0090] The canister 90 is not particularly limited and can be any canister commonly used for purifying ceramic honeycomb filters, such as those for automobile exhaust. Examples of materials for the canister 90 include ferritic stainless steel. The size of the canister 90 is preferably such that it can be pressed in while the gasket 95 is wound around the honeycomb structure 6 and the honeycomb filter 7. A canister with a length of approximately 100 to 300 mm is preferred for the canister 90.

[0091] As a method for arranging the cellular structure 6 and the cellular filter 7 at intervals, for example, one could be to arrange them separately. Figure 2 The method shown describes the arrangement of the partition plates 96 and the like between them. For example, stainless steel or other metals can be used as the material for the partition plates 96.

[0092] <Manufacturing Method of Waste Gas Purification Device>

[0093] Next, the manufacturing method of the exhaust gas purification device of this utility model will be described. The manufacturing method of the exhaust gas purification device of this utility model is not particularly limited; for example, the following methods can be cited.

[0094] The manufacturing method includes: a honeycomb structure forming step, in which a catalyst slurry containing a ternary catalyst flows from a first inflow side end face of a first honeycomb substrate into multiple compartments, and the catalyst slurry (supporting the ternary catalyst) is coated on the wall surface of the multiple compartments to form a honeycomb structure, wherein the first honeycomb substrate is obtained by firing a first honeycomb molded body having porous walls dividing to form multiple compartments, the multiple compartments extending from the first inflow side end face to the first outflow side end face and forming a flow path for the fluid; and a honeycomb filter forming step, in which a honeycomb filter is formed by dividing the honeycomb structure into a honeycomb structure. After sealing the openings of predetermined compartments on one end face and the openings of remaining compartments on the other end face of a second honeycomb molded body with porous partition walls forming multiple compartments, a honeycomb filter with sealed openings is formed by firing. This filter is then formed on a second honeycomb substrate and the second inflow-side end face of the second honeycomb substrate, where the openings of predetermined compartments and the openings of remaining compartments on the second outflow-side end face are fitted with sealed openings. The multiple compartments extend from the second inflow-side end face to the second outflow-side end face, forming a flow path for fluid. An assembly process is also performed, where an inlet for waste gas inflow is provided... A honeycomb structure is arranged on the inlet side of the tank, which is the outlet for the purified waste gas. The first inlet side face is facing the inlet side of the tank. A honeycomb filter is arranged on the outlet side of the tank, with the second outlet side facing the outlet side of the tank. The honeycomb structure and the honeycomb filter are housed within the tank. In the honeycomb structure forming process, the ratio of the length along the central axis of the honeycomb structure to the length along the central axis of the honeycomb filter is 0.1 to 0.5. The cell density of the first honeycomb substrate constituting the honeycomb structure is greater than the cell density of the second honeycomb substrate constituting the honeycomb filter. The opening ratio of the first honeycomb substrate is greater than the opening ratio of the second honeycomb substrate of the honeycomb filter. The diameter of the honeycomb structure is the same as or smaller than the diameter of the honeycomb filter. The honeycomb filter formed in the honeycomb filter forming process preferably does not carry a catalyst, or carries a catalyst with a catalyst loading per unit volume less than the catalyst loading per unit volume of the ternary catalyst carried in the honeycomb structure. Through the above process, the waste gas purification device of this invention can be manufactured.

[0095] <About the honeycomb structure formation process>

[0096] The first honeycomb substrate used in the formation process of the honeycomb structure can be manufactured as follows: First, the molding raw materials are mixed to form a blank. Next, the obtained blank is extruded and shaped into a honeycomb shape to obtain a first honeycomb molded body. Next, the obtained first honeycomb molded body is fired to obtain the first honeycomb substrate.

[0097] The preferred forming material is a ceramic raw material with added dispersion medium and additives. Examples of additives include organic binders, pore-forming materials, and surfactants. Examples of dispersion mediums include water.

[0098] As a ceramic raw material, it is preferably selected from at least one group consisting of silicon carbide, silicon-silicon carbide composite materials, cordierite raw materials, mullite, alumina, spinel, silicon carbide-cordierite composite materials, lithium aluminum silicate, and aluminum titanate. Among them, cordierite raw materials with low coefficient of thermal expansion and excellent thermal shock resistance are preferred. The content of ceramic raw material relative to the total forming raw material is preferably 80-95% by mass.

[0099] Examples of organic binders include methylcellulose, hydroxypropoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, and polyvinyl alcohol. Methylcellulose and hydroxypropoxycellulose are preferred in combination. The binder content relative to the total molding material is preferably 1-10% by mass. They can be used alone or in combination of two or more.

[0100] As a pore-forming material, there are no particular limitations on any material that becomes porous after firing; examples include starch, foaming resin, water-absorbing resin, and silicone. The content of the pore-forming material relative to the total molding raw material is preferably 0-20% by mass. It can be used alone or in combination with two or more materials.

[0101] Surfactants such as ethylene glycol, dextrin, fatty acid soaps, and polyols can be used. They can be used alone or in combination of two or more. The surfactant content relative to the total molding raw material is preferably 0.1% to 5% by mass.

[0102] The content of the dispersion medium is preferably 0.1 to 5% by mass relative to the total amount of the forming raw material.

[0103] By adjusting the particle size and proportion of the ceramic raw materials (aggregate particles) used, as well as the particle size and proportion of the added pore-forming materials, a porous substrate with the desired porosity and average fine pore size can be obtained.

[0104] There are no particular limitations on the method for mixing raw materials to form blanks; for example, methods such as using a kneader or a vacuum ply mill can be used. Extrusion molding can be performed using a die with the desired compartment shape, compartment thickness, and compartment density. As for the die material, a wear-resistant, ultra-hard alloy is preferred.

[0105] The firing temperature can be appropriately determined according to the material of the first honeycomb molded body. For example, when the material of the first honeycomb molded body is cordierite, the firing temperature is preferably 1380 to 1450°C, and more preferably 1400 to 1440°C. In addition, the firing time is preferably set to 3 to 10 hours.

[0106] Alternatively, the first honeycomb molded body can be dried before firing. The drying method is not particularly limited; examples include hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, and freeze drying. Dielectric drying, microwave drying, or hot air drying are preferred, either alone or in combination. Furthermore, the drying conditions are preferably set at a drying temperature of 30–150°C and a drying time of 1 minute to 2 hours.

[0107] Next, the method for coating the catalyst slurry (supported three-way catalyst) is not particularly limited, and known methods can be used. For example, firstly, a catalyst slurry containing a three-way catalyst is prepared. Then, the catalyst slurry is poured into the compartment by impregnation and attraction. Preferably, the catalyst slurry is coated on the entire surface of the partition wall within the compartment. Then, after the catalyst slurry has poured into the compartment, any remaining slurry is blown away with compressed air. Then, by drying and baking the catalyst slurry, a honeycomb structure with the three-way catalyst supported on the surface of the partition wall within the compartment can be obtained. The drying conditions are preferably set to 80–150°C for 1–6 hours. Alternatively, the baking conditions are preferably 450–700°C for 0.5–6 hours. It should be noted that, as components other than the catalyst contained in the catalyst slurry, alumina and the like can be cited.

[0108] <About the honeycomb filter forming process>

[0109] The second honeycomb molded body used in the honeycomb filter forming process can be made as follows: The clay is extruded into a honeycomb shape in a manner that meets the following conditions to obtain the second honeycomb molded body.

[0110] In the extrusion molding process of this step, the blank extruded from the die is cut such that the ratio of the length of the central axis of the honeycomb structure to the length of the central axis of the honeycomb filter is 0.1 to 0.5. Furthermore, the die is used such that the cell density of the first honeycomb substrate of the honeycomb structure is greater than the cell density of the second honeycomb substrate of the honeycomb filter, the opening ratio of the first honeycomb substrate of the honeycomb structure is greater than the opening ratio of the second honeycomb substrate of the honeycomb filter, and furthermore, the diameter of the honeycomb structure is the same as or smaller than the diameter of the honeycomb filter.

[0111] One method for sealing the openings of the compartments in the second honeycomb molded body is to fill the openings with a sealing material. Specifically, as a method of filling the sealing material, a mask is applied to one end face of the second honeycomb molded body to block the openings of predetermined compartments. Here, there are no particular limitations on the method of applying the mask, but it is preferable to alternately seal the openings of predetermined compartments in the second outflow side end face and the openings of remaining compartments in the second inflow side end face of the second honeycomb substrate, and to apply the mask in a checkered pattern on both end faces. Then, a slurry-like sealing material comprising a ceramic raw material, water or alcohol, and an organic binder is stored in a storage container. As the ceramic raw material, it is preferable to use the same ceramic raw material as the raw material for the second honeycomb molded body. The ceramic raw material is preferably 70-90% by mass of the total sealing material. Additionally, water or alcohol is preferably 10-30% by mass of the total sealing material, and the organic binder is preferably 0.1-2.0% by mass of the total sealing material. Examples of organic binders include hydroxypropoxymethylcellulose and methylcellulose. Then, the end with the mask applied is immersed in a storage container, and a sealing material is filled into the opening of the unmasked compartment to form a sealing portion. The viscosity of the sealing material is preferably 600 to 1200 Pa·s. Furthermore, the viscosity of the sealing material is measured at 30°C using a rotational viscometer at a rotational speed of 30 rpm.

[0112] Then, a mask is applied to the other end face of the second honeycomb molded body to block the openings of the remaining compartments. Next, the masked end face is immersed in a storage container containing a slurry-like sealing material, and the sealing material is filled into the openings of the unmasked compartments to form sealing portions. In this way, a honeycomb filter molded body can be obtained in which the openings of predetermined compartments on one end face of the second honeycomb molded body and the openings of the remaining compartments on the other end face are equipped with sealing portions.

[0113] The firing temperature during the firing of the honeycomb filter molded body can be appropriately determined according to the material of the honeycomb filter molded body. For example, when the material of the honeycomb filter molded body is cordierite, the firing temperature is preferably 1380 to 1450°C, and more preferably 1400 to 1440°C. In addition, the firing time is preferably set to about 3 to 10 hours.

[0114] Alternatively, the honeycomb filter molded body can be dried before firing. The drying method is not particularly limited; examples include hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, and freeze drying. Dielectric drying, microwave drying, or hot air drying are preferred, either alone or in combination. Furthermore, the drying conditions are preferably set at a drying temperature of 30°C to 150°C and a drying time of 1 minute to 2 hours.

[0115] It should be noted that, before the second honeycomb molding body forms the sealing portion, the second honeycomb molding body can be fired to obtain a honeycomb fired body. The opening of the predetermined compartment in one end face and the opening of the remaining compartment in the other end face of the obtained honeycomb fired body are formed into sealing portions, and then further fired to obtain a honeycomb filter.

[0116] It should be noted that a honeycomb filter can be obtained by coating a honeycomb filter structure with a catalyst slurry (supported catalyst) using a known method. For example, the method of coating the catalyst slurry involves first preparing a catalyst slurry containing a ternary catalyst. Then, the prepared catalyst slurry is impregnated and drawn into the compartment. Preferably, the catalyst slurry is coated on the entire surface of the partition wall within the compartment. After the catalyst slurry has flowed into the compartment, any remaining slurry is blown away with compressed air. Then, by drying and baking the catalyst slurry, a sealed honeycomb structure with the catalyst supported on the partition wall surface within the compartment can be obtained. The drying conditions are preferably set to 80–150°C for 1–6 hours. The baking conditions are preferably 450–700°C for 0.5–6 hours. It should be noted that, as components other than the catalyst contained in the catalyst slurry, alumina and the like can be cited.

[0117] <About the assembly process>

[0118] In the assembly process, after covering the outer periphery of the honeycomb structure and the honeycomb filter with padding (cushioning material), the honeycomb structure and the honeycomb filter, covered with padding, are placed inside the tank. At this point, it is preferable that the honeycomb structure and the honeycomb filter are housed in a compressed state within the tank. Ceramic fiber padding can be used as an example. This prevents the honeycomb structure and the honeycomb filter from moving within the tank.

[0119] The tank body can use conventionally known tank bodies, for example, it can be manufactured by stamping and welding sheet material made of ferritic stainless steel. Specifically, the diameter of the inlet of the tank body is preferably 30 to 80 mm, and the diameter of the outlet is preferably 30 to 80 mm.

[0120] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to these examples. Obviously, anyone with ordinary knowledge in the technical field to which the present invention pertains can conceive of various modifications or alterations within the scope of the technical concept described in the claims, and these are naturally understood to fall within the technical scope of the present invention.

[0121] [Example]

[0122] The present invention will be described in more detail below through embodiments. The present invention is not limited to these embodiments.

[0123] (Example 1)

[0124] [Fabrication of Honeycomb Structures] (Honeycomb Structure Formation Process)

[0125] First, as raw materials for cordierite petrochemicals, alumina, aluminum hydroxide, kaolin, talc, and silica are used. 35 parts by weight of dispersion medium, 6 parts by weight of organic binder, and 0.5 parts by weight of dispersant are added to 100 parts by weight of the cordierite petrochemical raw materials, respectively, and then mixed and kneaded to prepare clay. Water is used as the dispersion medium, hydroxypropyl methylcellulose as the organic binder, and ethylene glycol as the dispersant.

[0126] Next, the clay is extruded using a predetermined mold to form a honeycomb molded body with quadrilateral compartments and an overall cylindrical shape. Then, the honeycomb molded body is dried using a microwave dryer, and further dried completely using a hot air dryer. Afterward, both ends of the honeycomb molded body are cut off and adjusted to predetermined dimensions. Finally, it is fired at 1410–1440°C for 5 hours to obtain a fired honeycomb body.

[0127] Next, a mixture of γAl₂O₃ with an average particle size of 100 μm and CeO₂ with an average particle size of 100 μm (specific surface area 50 m²) was prepared. 2 / g) Wet crushing was performed using a ball mill to obtain crushed particles with an average particle size of 5 μm. The obtained crushed particles were impregnated in a solution containing Pt and Rh, so that Pt and Rh were supported in the pores of the crushed particles. Then, acetic acid and water were added to the crushed particles supported with Pt and Rh to obtain a coating slurry. The inflow-side end of the prepared honeycomb sintered body was impregnated with the obtained coating slurry. Then, with the inflow-side end impregnated, the coating slurry was vacuumed from the outflow-side end face of the honeycomb sintered body, thereby coating the slurry on the partition wall of the honeycomb sintered body to form a catalyst layer. Then, it was dried and fired at 600°C for 3 hours to produce a honeycomb structure.

[0128] The fabricated honeycomb structure has a diameter D1 of 120 mm, a length L1 along the central axis of 70 mm, a wall thickness of 0.05 mm, and a cell density of 139.5 cells / cm². 2 (900cpsi), the compartment spacing is 0.85mm, the opening rate of the first honeycomb substrate is 88%, the porosity of the partition wall is 55%, and the amount of precious metal in the three-way catalyst is 2g.

[0129] It should be noted that the catalyst supported on the honeycomb structure has a loading of 1 g / L per unit volume for oxides (γAl2O3 and CeO2) in the Pt honeycomb catalyst body, and a loading of 0.2 g / L per unit volume in the Rh honeycomb catalyst body. Furthermore, the average pore size of the catalyst layer is the same as the average particle size of the broken particles, which is 5 μm.

[0130] [Cellular Filter Fabrication] (Cellular Filter Formation Process)

[0131] First, as a cordierite petrochemical raw material, alumina, aluminum hydroxide, kaolin, talc, and silica are used. To each 100 parts by weight of the cordierite petrochemical raw material, 13 parts by weight of a pore-forming material, 35 parts by weight of a dispersion medium, 6 parts by weight of an organic binder, and 0.5 parts by weight of a dispersant are added, followed by mixing and kneading to prepare a blank. Water is used as the dispersion medium, coke with an average particle size of 1–10 μm is used as the pore-forming material, hydroxypropyl methylcellulose is used as the organic binder, and ethylene glycol is used as the dispersant. Foaming resins, water-absorbing resins, etc., can also be used as the pore-forming material. By appropriately controlling the particle size and amount of the pore-forming material, the fine pore size and porosity of the partition wall can be controlled.

[0132] Next, the clay is extruded using a predetermined mold to form a honeycomb structure with quadrilateral compartments and a cylindrical overall shape.

[0133] The honeycomb molded body is dried using a microwave dryer, and then completely dried using a hot air dryer. Both ends of the honeycomb molded body are then cut off and adjusted to predetermined dimensions. Next, a portion of the openings of the compartments on one end face of the honeycomb molded body is masked. The masked end is immersed in a sealing slurry containing cordierite, and then, for the other end, the openings of the sealed compartments on the aforementioned end face are masked. Then, by immersing in the sealing slurry, the sealing slurry is filled into the openings of the predetermined compartments on the outflow side end face in a grid pattern, alternating between the openings of predetermined compartments on one end face and the openings of the remaining compartments on the other end face. The honeycomb molded body filled with sealing slurry is then dried using a hot air dryer and further fired at 1410–1440°C for 5 hours, thereby producing a honeycomb filter.

[0134] The fabricated honeycomb filter has a diameter D2 of 120 mm, a length L2 along the central axis of 80 mm, a partition wall thickness of 0.152 mm, and a cell density of 56 cells / cm³. 2 (360cpsi), the compartment spacing is 1.34mm, the opening rate of the second honeycomb substrate is 79%, the porosity of the partition wall is 45%, and the amount of precious metal in the three-way catalyst is 1g.

[0135] Furthermore, the fabricated honeycomb structure and honeycomb filter are housed within a single metal container with an inlet and an outlet, and equipped with a pair of 2mm thick partition plates. During installation, a ceramic fiber-based gasket is used to cover the outer periphery of both the honeycomb structure and the honeycomb filter, which are then pressed into the container for fixation. This creates an exhaust gas purification device. It should be noted that the honeycomb structure and honeycomb filter are maintained at a 30mm distance between their end faces (between the first outlet end face and the second inlet end face) by the partition plates. This device is then installed in the exhaust system of a range-extended battery electric vehicle (REEV) that uses a 2000cc gasoline engine as a generator (range extender).

[0136] The compactness, heating of the honeycomb structure, cold start purification, hot start purification, end face ash clogging pressure loss, filter strength, and catalyst clogging of the filter partition were evaluated using the following methods.

[0137] [Methods for evaluating compactness]

[0138] Compactness is evaluated by comparing the length from the first inflow side end face of the honeycomb structure to the second outflow side end face of the honeycomb filter (length L1 of the honeycomb structure + length L2 of the honeycomb filter + distance between them). The distance between the honeycomb structure with a sensor mounting slot and the honeycomb filter is 10 mm, and the distance without a sensor mounting slot is 30 mm. A length of 170 mm or less is designated as "Excellent," more than 170 mm but less than 210 mm as "Good," more than 210 mm but less than 220 mm as "Acceptable," and more than 220 mm as "Unacceptable." "Excellent" to "Acceptable" are considered acceptable.

[0139] [Evaluation Methods for Temperature Rise in Cellular Structures]

[0140] The temperature rise of the honeycomb structure is evaluated by measuring the time it takes for the center temperature of the honeycomb structure to reach 200°C immediately after the engine is started. A time of less than 15 seconds is classified as "Excellent," more than 15 seconds but less than 20 seconds as "Good," more than 20 seconds but less than 25 seconds as "Acceptable," and more than 25 seconds as "Unacceptable." "Excellent" to "Acceptable" are considered acceptable.

[0141] [Evaluation Methods for Cold Start Purification]

[0142] Cold start purification is evaluated by measuring NOx emissions in the WLTC cold start operation assessment. NOx emissions below 60 mg / km are classified as "Excellent," above 60 mg / km but below 80 mg / km as "Good," above 80 mg / km but below 100 mg / km as "Acceptable," and above 100 mg / km as "Unacceptable." "Excellent" to "Acceptable" are considered acceptable.

[0143] [Evaluation Methods for Hot-Start Purification]

[0144] Hot-start purification is evaluated by measuring NOx emissions in the WLTC hot-start operation assessment. NOx emissions below 20 mg / km are classified as "Excellent," above 20 mg / km but below 60 mg / km as "Good," below 60 mg / km as "Acceptable," and above 60 mg / km as "Unacceptable." "Excellent" to "Acceptable" are considered acceptable.

[0145] [Evaluation Method for Pressure Loss Due to Ash Clogging at the End Face]

[0146] The pressure loss due to end-face ash blockage is evaluated by comparing the pressure difference before and after the first and fifth cycles of operation in WLTC mode, repeated five times. A difference of less than 1% between the first and fifth cycles is classified as "Excellent," more than 1% but less than 2% as "Good," more than 2% but less than 3% as "Acceptable," and more than 3% as "Unacceptable." "Excellent" to "Acceptable" are then classified as "Pass."

[0147] [Methods for evaluating filter strength]

[0148] Filter strength is evaluated based on the isostatic pressure strength of the honeycomb filter. Isostatic pressure strength is the destructive strength measured by applying hydrostatic pressure in water. The honeycomb filter is clamped with plates protecting the second inflow and second outflow end faces. The entire honeycomb filter is placed in a rubber container and inserted into a hydrostatic pressure tank. The hydrostatic pressure in the tank is gradually increased, and the hydrostatic pressure at the moment of detected destructive sound is taken as the isostatic pressure strength. An isostatic pressure strength of 3 MPa or higher is defined as "Excellent," less than 3 MPa but more than 2 MPa as "Good," less than 2 MPa but more than 1.2 MPa as "Acceptable," and less than 1.2 MPa as "Unacceptable." "Excellent" to "Acceptable" are considered acceptable.

[0149] [Evaluation method for catalyst blockage in filter partitions]

[0150] Catalyst clogging of the filter partition was evaluated based on the rate of increase in pressure drop before and after catalyst loading (pressure drop after catalyst loading / pressure drop before catalyst loading). For both the pre- and post-catalyst-loaded honeycomb filters, a pressure drop of 10 Nm was applied. 3 A constant flow of room temperature air per minute circulates within the compartments of the honeycomb filter, and pressure loss is measured as the pressure difference before and after the filter. A pressure loss increase rate of less than 20% is classified as "Excellent," more than 20% but less than 50% as "Good," more than 50% but less than 60% as "Acceptable," and more than 60% as "Unacceptable." "Excellent" to "Acceptable" are then classified as "Pass."

[0151] In the table below, regarding the comprehensive judgment, a rating of "Excellent" is defined as either "Excellent" for compactness or two purification performance aspects (cold start purification and hot start purification) among the seven evaluations, and "Good" or "Not Good" for the other four evaluation items. Additionally, a rating without "Good" or "Not Good" is defined as "Good"; a rating without "Not Good" is defined as "Good"; and a rating with one "Not Good" is defined as "Not Good".

[0152] (Example 2)

[0153] Example 2 is the same as Example 1 except that the porosity of the honeycomb structure is changed to 40%.

[0154] (Example 3)

[0155] Example 3 changed the cell density of the honeycomb structure to 93.0 cells / cm². 2 Except for changing the porosity of the honeycomb structure to 45%, it is the same as in Example 1.

[0156] (Example 4)

[0157] Example 4 changed the cell density of the honeycomb structure to 116.3 cells / cm². 2 Except for changing the opening ratio of the honeycomb structure to 85% and the porosity of the honeycomb structure to 55%, it is the same as in Example 1.

[0158] (Example 5)

[0159] In Example 5, the length L1 of the honeycomb structure is changed to 48mm, a sensor slot is set in the honeycomb structure, and an oxygen sensor is mounted in its space. This changes the distance between the honeycomb structure and the honeycomb filter to 10mm and the porosity of the honeycomb filter to 50%. Otherwise, it is the same as Example 4.

[0160] (Example 6)

[0161] Example 6 is the same as Example 4 except that the length L1 of the honeycomb structure is changed to 108mm.

[0162] (Example 7)

[0163] Example 7 is the same as Example 4 except that the aperture ratio of the honeycomb structure is changed to 87%.

[0164] (Example 8)

[0165] Example 8 is the same as Example 4 except that the aperture ratio of the honeycomb structure is changed to 92%.

[0166] (Example 9)

[0167] Example 9 is the same as Example 4 except that the porosity of the honeycomb structure is changed to 50%.

[0168] (Example 10)

[0169] In Example 10, the length of the honeycomb structure was changed to 60 mm, a sensor slot was set in the honeycomb structure, and an oxygen sensor was installed in its space. This changed the distance between the honeycomb structure and the honeycomb filter to 10 mm, and the porosity of the honeycomb filter to 50%. Otherwise, it was the same as Example 2.

[0170] (Example 11)

[0171] Example 11 changed the cell density of the honeycomb structure to 77.5 cells / cm². 2 Except for the above, it is the same as in Example 3.

[0172] (Example 12)

[0173] Example 12, except that the opening ratio of the honeycomb filter is changed to 80% and the cell density of the honeycomb filter is changed to 50 cells / cm², is an improvement. 2 Except for the above, it is the same as in Example 3.

[0174] (Example 13)

[0175] Example 13, except that the opening ratio of the honeycomb filter was changed to 77% and the cell density of the honeycomb filter was changed to 70 cells / cm², was different. 2 Except for the above, it is the same as in Example 3.

[0176] (Example 14)

[0177] Example 14 is the same as Example 3 except that the length of the honeycomb filter is changed to 70 mm and the porosity of the honeycomb filter is changed to 50%.

[0178] (Example 15)

[0179] Example 15 is the same as Example 3 except that the length of the honeycomb filter is changed to 110 mm.

[0180] (Example 16)

[0181] Example 16 is the same as Example 13 except that the thickness of the septum of the honeycomb filter is changed to 0.102 mm.

[0182] (Example 17)

[0183] Example 17 is the same as Example 13 except that the thickness of the septum of the honeycomb filter is changed to 0.125 mm.

[0184] (Example 18)

[0185] Example 18 is the same as Example 12 except that the thickness of the septum of the honeycomb filter is changed to 0.165 mm.

[0186] (Example 19)

[0187] Example 19 is the same as Example 12 except that the thickness of the septum of the honeycomb filter is changed to 0.170 mm.

[0188] (Example 20)

[0189] Example 20 is the same as Example 2 except that the length of the honeycomb structure is changed to 60 mm and the porosity of the honeycomb filter is changed to 65%.

[0190] (Example 21)

[0191] Example 21 is the same as Example 20 except that the diameter of the honeycomb structure and the diameter of the honeycomb filter are changed to 140 mm.

[0192] (Comparative Example 1)

[0193] Comparative Example 1 is the same as Example 3 except that the length of the honeycomb structure is changed to 140 mm and the aperture ratio of the honeycomb structure is changed to 91%.

[0194] (Comparative Example 2)

[0195] Comparative Example 2 is the same as Example 3 except that the length of the honeycomb structure is changed to 40 mm and the aperture ratio of the honeycomb structure is changed to 89%.

[0196] (Comparative Example 3)

[0197] Comparative Example 3 is the same as Example 3 except that the length of the honeycomb structure is changed to 80 mm and the aperture ratio of the honeycomb structure is changed to 82%.

[0198] (Comparative Example 4)

[0199] Comparative Example 4 is the same as Example 3 except that the porosity of the honeycomb structure is changed to 28% and the length of the honeycomb structure is changed to 80mm.

[0200] (Comparative Example 5)

[0201] Comparative Example 5, except that the cell density of the honeycomb structure was changed to 62 cells / cm² 2 Except for changing the length of the honeycomb structure to 80mm, it is the same as in Example 3.

[0202] (Comparative Example 6)

[0203] Comparative Example 6, except that the cell density of the honeycomb filter was changed to 47 cells / cm² 2 Except for that, it is the same as in Example 7.

[0204] (Comparative Example 7)

[0205] Comparative Example 7, except that the cell density of the honeycomb filter was changed to 71 cells / cm² 2 Except for that, it is the same as in Example 7.

[0206] Table 1

[0207]

[0208] The ratio of the length L1 to the diameter D1 along the central axis of the honeycomb structure, L1 / D1, satisfies 0.4 ≤ L1 / D1 ≤ 0.9; the porosity of the cell walls of the honeycomb structure is 40% or more; the opening ratio of the first honeycomb substrate of the honeycomb structure is 85% or more; and the cell density of the honeycomb structure is 77.5 cells / cm². 2 The above-mentioned cell density of the honeycomb filter is 50 cells / cm². 2 More than 70 per cm 2 In the following Examples 1 to Examples 21, all evaluation items were rated as "Acceptable" to "Excellent".

[0209] In contrast, Comparative Examples 1 and 2 show ratios where L1 / D1 does not satisfy 0.4 ≤ L1 / D1 ≤ 0.9; Comparative Example 3 shows the opening ratio of the first cell substrate of the cell structure is less than 85%; Comparative Example 4 shows the porosity of the cell wall of the cell structure is less than 40%; and Comparative Example 5 shows the cell density of the cell structure is less than 77.5 cells / cm³. 2 Comparative Example 5, and the cell density of the honeycomb filter is 50 cells / cm³. 2 70 or more per cm 2 In Comparative Examples 6 and 7, the evaluation for any evaluation item is "not possible".

[0210] Based on these results, the ratio of the length L1 to the diameter D1 along the central axis of the honeycomb structure, L1 / D1, satisfies 0.4 ≤ L1 / D1 ≤ 0.9; the porosity of the honeycomb structure's partitions is above 40%; the opening rate of the first honeycomb substrate is above 85%; and the cell density of the honeycomb structure is 77.5 cells / cm². 2 The above indicates that the cell density of the honeycomb filter is 50 cells / cm². 2 More than 70 per cm 2 This ensures sufficient contact area between the honeycomb structure and the exhaust gas, and accelerates the heating rate of the honeycomb structure. Even when the engine load decreases and the exhaust gas temperature drops, the part containing the catalyst can still maintain adequate temperature insulation.

[0211] In the embodiments, Examples 5, 10, 14, 20, and 21, where the porosity of the honeycomb filter is 50% or higher, exhibited excellent evaluations of compactness and purification performance. This is believed to be because it avoids the increase in pressure drop associated with partition blockage caused by catalyst loading, reduces ash accumulation capacity while allowing for pressure drop increases due to ash accumulation, achieves compactness, and improves catalyst utilization by preventing blockage, thus enhancing purification performance. These results indicate that achieving a porosity of 50% or higher in the honeycomb filter is an effective method for simultaneously satisfying both compactness and purification performance.

[0212] Furthermore, it is known that in all embodiments, the ratio of the length L2 of the central axis direction of the cellular filter to the diameter D2, L2 / D2, satisfies 0.6≤L2 / D2≤0.9. Within this range, it is possible to ensure the volume of the cellular filter while suppressing the installation of a length that can be accommodated. Therefore, by adjusting other specifications, it is possible to make all evaluation items combinable.

[0213] Symbol Explanation

[0214] 1—Gas engine mounted vehicle; 3—Battery; 4—Gas engine; 4b—Exhaust gas; 5—Exhaust gas purification device; 6—Honeycomb structure; 60—First honeycomb substrate; 61—First inflow side end face; 62—First outflow side end face; 63—Compartment; 64—Partition wall; 65—Gate; 7—Honeycomb filter; 70—Second honeycomb substrate; 71—Second inflow side end face; 72—Second outflow side end face; 73—Compartment; 731—First compartment; 732—Second compartment; 74—Partition wall; 75—Sealing part; 8—Exhaust gas sensor.

Claims

1. An exhaust gas purification device, used in gasoline engine-equipped vehicles, characterized in that, have: A honeycomb structure having a first honeycomb substrate having porous partitions dividing a plurality of compartments extending from a first inflow side end face to a first outflow side end face, wherein the compartments of the first honeycomb substrate are open at both ends. as well as A honeycomb filter has a second honeycomb substrate and a sealing portion. The second honeycomb substrate has porous partitions that divide into multiple compartments extending from a second inflow side end face to a second outflow side end face. The sealing portion seals the compartments of the second honeycomb substrate at either the second inflow side end face or the second outflow side end face. The compartments of the second honeycomb substrate include a first compartment and a second compartment. The first compartment is open at the second inflow side end face and sealed at the second outflow side end face, and the second compartment is open at the second outflow side end face and sealed at the second inflow side end face. The honeycomb filter is disposed downstream of the honeycomb structure relative to the flow of exhaust gas. The ratio of the length L1 along the central axis of the honeycomb structure to its diameter D1, L1 / D1, satisfies 0.4 ≤ L1 / D1 ≤ 0.

9. The porosity of the partition walls of the honeycomb structure is 40% or more. A ternary catalyst is coated on the partition wall of the honeycomb structure. The opening ratio of the first honeycomb substrate of the honeycomb structure is 85% or more. The cell density of the honeycomb structure is 77.5 cells / cm². 2 above, A ternary catalyst is coated on the partition wall of the honeycomb filter. The cell density of the honeycomb filter is 50 cells / cm². 2 More than 70 per cm 2 the following.

2. The waste gas purification device according to claim 1, characterized in that, The porosity of the septum of the honeycomb filter is 50% or more.

3. The waste gas purification device according to claim 1, characterized in that, A gasoline engine-equipped vehicle is a range-extended electric vehicle with a gasoline engine that serves as a range extender for charging the battery.

4. The waste gas purification device according to claim 1, characterized in that, The thickness of the partition wall of the cellular filter is greater than 0.102 mm and less than 0.170 mm.

5. The waste gas purification device according to claim 1, characterized in that, The ratio of the length L2 of the cellular filter along its central axis to its diameter D2, L2 / D2, satisfies 0.6 ≤ L2 / D2 ≤ 0.

9.

6. The waste gas purification device according to claim 1, characterized in that, It also features an exhaust gas sensor that detects the oxygen or NOx concentration in the exhaust gas. The first honeycomb substrate is provided with a groove or hole extending radially inward from the outer peripheral surface. The exhaust gas sensor is inserted into the slot or hole.

7. The waste gas purification device according to claim 1, characterized in that, The porosity of the partition wall of the honeycomb structure is less than 55%.

8. The waste gas purification device according to claim 1, characterized in that, The opening ratio of the first honeycomb substrate of the honeycomb structure is less than 92%.

9. The waste gas purification device according to claim 1, characterized in that, The cell density of the honeycomb structure is 140 cells / cm². 2 the following.

10. A vehicle equipped with a gasoline engine, characterized in that, The exhaust gas purification device is provided with any one of claims 1 to 9.

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