Honeycomb Filter

Abstract

This invention provides a honeycomb filter that ensures ash accumulation volume and reduces the overall capacity of the honeycomb filter, while also reducing the possibility of damage due to gasket surface pressure. The honeycomb filter of this invention is a wall-flow type, comprising a honeycomb substrate and sealing sections. In the exhaust system of a vehicle equipped with a gasoline engine, it is positioned downstream of a flow-through honeycomb structure relative to the flow of exhaust gas. The main component of the partitions is cordierite, the opening ratio of the honeycomb substrate is 75% or more, and the porosity of the partitions is 60% or more. When assembled into an exhaust gas purification device, the honeycomb filter has a catalyst loaded in the partitions. The average flexural strength at four points is 1.1 MPa or more when the partitions are not loaded with catalyst, or 1.5 MPa or more when the partitions are loaded with catalyst.

Description

Technical Field

[0001] This utility model relates to a wall-flow type honeycomb filter, which is configured downstream of a flow-type honeycomb structure in the exhaust system of a vehicle equipped with a gasoline engine, relative to the flow of exhaust gas, for purifying particles contained in the exhaust gas. Background Technology

[0002] To address increasingly stringent vehicle emissions regulations, it is desirable to ensure early catalyst warm-up during engine startup and to maintain catalyst temperature even under low exhaust temperatures when engine load decreases. Regarding exhaust purification, catalysts are needed to remove NOx, HC, and CO, as well as particulate matter generated during fuel combustion. Furthermore, the need to suppress CO2 emissions is increasing, leading to the widespread adoption of electric vehicles with engines (internal combustion engines) and motors as power sources. Engines are used as power sources for both driving and / or power generation. In such electric vehicles, the engine starts and stops frequently, thus requiring high levels of early start-up temperature and excellent catalyst insulation during shutdown.

[0003] Patent Document 1 discloses an exhaust gas purification device that connects a honeycomb structure (honeycomb catalyst body) and a honeycomb filter (sealed honeycomb structure) in series, but this exhaust gas purification device is not specifically designed for electric vehicles. A three-way catalyst is supported in both the honeycomb structure and the honeycomb filter. In Patent Document 1, the honeycomb structure is smaller than the honeycomb filter (specifically, the ratio of the length of the honeycomb structure to the length of the honeycomb filter is 0.1 to 0.5). This reduction in the size of the honeycomb structure allows for earlier temperature rise.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2011-167581 Utility Model Content

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

[0008] Exhaust gases from gasoline-powered vehicles contain ash from lubricating oil and fuel. If this ash accumulates in the honeycomb filter, it becomes a major cause of pressure loss, leading to reduced engine thermal efficiency and potentially increased fuel consumption and CO2 emissions. To reduce this pressure loss, increasing the volume of the honeycomb filter is considered. However, increasing the volume of the honeycomb filter reduces the space available for peripheral components such as batteries in electric vehicles. Furthermore, increasing the volume of the honeycomb filter requires a large amount of precious metals to meet emissions regulations, becoming a major reason for increased costs.

[0009] Even with limited volume in the honeycomb filter, increasing the aperture ratio can ensure sufficient ash accumulation volume. Furthermore, increasing the aperture ratio reduces the heat capacity of the honeycomb filter, allowing it to heat up earlier and thus reducing the amount of precious metals required. However, increasing the aperture ratio can easily reduce the filter's strength, potentially causing damage when using gaskets to hold the filter within the tank.

[0010] This invention was made to solve the aforementioned problems, and one of its objectives is to provide a honeycomb filter that can ensure the accumulation volume of ash and reduce the heat capacity of the honeycomb filter, while also reducing the possibility of damage caused by the surface pressure of the gasket.

[0011] Methods for solving problems

[0012] [1] In one embodiment of this utility model, a honeycomb filter is provided, which is a wall-flow type honeycomb filter.

[0013] The honeycomb filter has a honeycomb substrate and a sealing portion. The honeycomb substrate has a porous partition wall that divides into multiple cells extending from an inflow side end face to an outflow side end face. The sealing portion seals the cells on the inflow side end face or the outflow side end face. The cells of the honeycomb substrate include a first cell that opens on the inflow side end face and is sealed on the outflow side end face, and a second cell that opens on the outflow side end face and is sealed on the inflow side end face.

[0014] In the exhaust gas purification system of a vehicle equipped with a gasoline engine, the honeycomb filter is positioned downstream of a flow-through honeycomb structure relative to the flow of exhaust gas.

[0015] The main component of the partition wall is cordierite.

[0016] The opening ratio of the honeycomb substrate is 75% or higher.

[0017] The porosity of the partition wall is over 60%.

[0018] When assembled into the exhaust gas purification device, a catalyst is supported on the partition wall.

[0019] The average flexural strength of the honeycomb filter at four points is 1.1 MPa or more when the partition wall is not loaded with catalyst, or the average flexural strength of the honeycomb filter at four points is 1.5 MPa or more when the partition wall is loaded with catalyst.

[0020] [2] This utility model may relate to the honeycomb filter described in the first item, wherein the average bending strength of the honeycomb filter at four points is 1.2 MPa or more when the partition wall is not loaded with catalyst, or the average bending strength of the honeycomb filter at four points is 1.7 MPa or more when the partition wall is loaded with catalyst.

[0021] [3] In one embodiment, this utility model relates to a honeycomb filter, which is a wall-flow type honeycomb filter.

[0022] The honeycomb filter has a honeycomb substrate and a sealing portion. The honeycomb substrate has a porous partition wall that divides into multiple cells extending from an inflow side end face to an outflow side end face. The sealing portion seals the cells on the inflow side end face or the outflow side end face. The cells of the honeycomb substrate include a first cell that opens on the inflow side end face and is sealed on the outflow side end face, and a second cell that opens on the outflow side end face and is sealed on the inflow side end face.

[0023] In the exhaust gas purification system of a vehicle equipped with a gasoline engine, the honeycomb filter is positioned downstream of a flow-through honeycomb structure relative to the flow of exhaust gas.

[0024] The main component of the partition wall is cordierite.

[0025] The opening ratio of the honeycomb substrate is 77% or higher.

[0026] The porosity of the partition wall is greater than 50% and less than 59%.

[0027] When assembled into the exhaust gas purification device, a catalyst is supported on the partition wall.

[0028] The average flexural strength of the honeycomb filter at four points is 1.5 MPa or more when the partition wall is not loaded with catalyst, or the average flexural strength of the honeycomb filter at four points is 1.8 MPa or more when the partition wall is loaded with catalyst.

[0029] [4] In one embodiment, this utility model relates to a honeycomb filter, which is a wall-flow type honeycomb filter.

[0030] The honeycomb filter has a honeycomb substrate and a sealing portion. The honeycomb substrate has a porous partition wall that divides into multiple cells extending from an inflow side end face to an outflow side end face. The sealing portion seals the cells on the inflow side end face or the outflow side end face. The cells of the honeycomb substrate include a first cell that opens on the inflow side end face and is sealed on the outflow side end face, and a second cell that opens on the outflow side end face and is sealed on the inflow side end face.

[0031] In the exhaust gas purification system of a vehicle equipped with a gasoline engine, the honeycomb filter is positioned downstream of a flow-through honeycomb structure relative to the flow of exhaust gas.

[0032] The main component of the partition wall is cordierite.

[0033] The opening ratio of the honeycomb substrate is 75% or higher.

[0034] The porosity of the partition wall is greater than 50% and less than 59%.

[0035] When assembled into the exhaust gas purification device, no catalyst is supported on the partition wall.

[0036] The average flexural strength of the honeycomb filter at four points when the partition wall is not loaded with catalyst is above 1.5 MPa.

[0037] [5] In one embodiment, this utility model relates to a honeycomb filter, which is a wall-flow type honeycomb filter.

[0038] The honeycomb filter has a honeycomb substrate and a sealing portion. The honeycomb substrate has a porous partition wall that divides into multiple cells extending from an inflow side end face to an outflow side end face. The sealing portion seals the cells on the inflow side end face or the outflow side end face. The cells of the honeycomb substrate include a first cell that opens on the inflow side end face and is sealed on the outflow side end face, and a second cell that opens on the outflow side end face and is sealed on the inflow side end face.

[0039] In the exhaust gas purification system of a vehicle equipped with a gasoline engine, the honeycomb filter is positioned downstream of a flow-through honeycomb structure relative to the flow of exhaust gas to purify the exhaust gas. When assembled into the exhaust gas purification system, the filter may or may not contain a catalyst in the partition wall.

[0040] The main component of the partition wall is cordierite.

[0041] The opening ratio of the honeycomb substrate is 75% or higher.

[0042] The average bending strength of the honeycomb filter at four points when assembled in the exhaust gas purification device is 1.5 MPa or more.

[0043] [6] This utility model may relate to the honeycomb filter described in any one of the first to fifth items, wherein the average isostatic pressure is above 1.2 MPa.

[0044] [7] This utility model may relate to a honeycomb filter as described in any one of the first to fifth items, wherein the partition contains more than 1 wt% of any one of cerium, zirconium and titanium.

[0045] [8] This utility model may relate to a honeycomb filter as described in any one of the first to fifth items, wherein the average coefficient of thermal expansion in the direction of pore extension from 40°C to 800°C is 1.2ppm / K or higher.

[0046] [9] This utility model may relate to a honeycomb filter as described in any one of the first to fifth items, wherein the partition has a glass layer comprising any one of cerium, zirconium and titanium, and the weight ratio of the glass layer exceeds 3%.

[0047]

[10] This utility model may relate to a honeycomb filter as described in any one of the first to fifth items, which is used in a range-extended electric vehicle having a gasoline engine as a range extender for charging a battery.

[0048] Utility Model Effect

[0049] According to one embodiment of the honeycomb filter of this utility model, the ash accumulation volume can be ensured and the heat capacity of the honeycomb filter can be reduced, while the possibility of damage caused by the surface pressure of the gasket can be reduced. Attached Figure Description

[0050] Figure 1 This is an explanatory diagram showing a vehicle 1 equipped with a gasoline engine that includes a honeycomb filter according to an embodiment of the present invention.

[0051] Figure 2 yes Figure 1 Cross-sectional view of the exhaust gas purification device 5.

[0052] Figure 3 It means Figure 2 The front view of the first inflow side end face 61 of the honeycomb structure 6.

[0053] Figure 4 It means Figure 2 A three-dimensional view of the honeycomb structure 6.

[0054] Figure 5 It means Figure 2 The front view of the second inflow side end face 71 of the cellular filter 7.

[0055] Figure 6 It means Figure 2 A 3D view of the honeycomb filter 7.

[0056] Figure 7 This is a schematic diagram illustrating the four-point bending test method.

[0057] Symbol Explanation

[0058] 1: Vehicle equipped with a gasoline engine; 2: Motor; 3: Battery; 4: Gasoline engine; 4a: Exhaust system; 4b: Exhaust gas; 5: Exhaust gas purification device; 6: Honeycomb structure; 7: Honeycomb filter; 63: Cell; 64: Partition; 73: Cell; 731: First cell; 732: Second cell; 74: Partition; 75: Sealing part. Detailed Implementation

[0059] Hereinafter, embodiments for implementing the present invention will be described with reference to the accompanying drawings. The present invention is not limited to any particular embodiment, and can be embodied by modifying the constituent elements without departing from its spirit. Furthermore, various embodiments can be formed by appropriately combining the multiple constituent elements disclosed in each embodiment. For example, some constituent elements may be deleted from all the constituent elements shown in the embodiments. Furthermore, constituent elements from different embodiments may be appropriately combined.

[0060] <Regarding vehicles equipped with gasoline engines>

[0061] Figure 1 This is an explanatory diagram showing a gasoline engine-mounted vehicle 1 that includes a honeycomb filter according to an embodiment of the present invention. (See diagram below.) Figure 1 As shown, the vehicle 1 equipped with a gasoline engine in this embodiment includes a motor 2, a battery 3, a gasoline engine 4, and an exhaust gas purification device 5.

[0062] 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 to move the vehicle 1 equipped with a gasoline engine. Battery 3 is connected to motor 2. Motor 2 can operate using the electricity stored in battery 3. Motor 2 can be configured to perform regenerative operation, storing the electricity generated by motor 2 in battery 3.

[0063] 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 vehicle 1 equipped with the gasoline engine can be driven by the output of the gasoline engine 4. When the gasoline engine 4 is used as a power source for generating electricity, its output shaft is connected to a generator, and the generator can be driven by the output of the gasoline engine 4. The generator can be a motor 2, or it can be installed separately from the motor 2. The gasoline engine 4 can be used only as a power source for driving, or it can be used only as a power source for generating electricity.

[0064] The vehicle 1 equipped with a gasoline engine 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 electric system, to the battery 3. Alternatively, the vehicle 1 equipped with a gasoline engine can also be a range-extended electric vehicle (EV), which has a gasoline engine 4 that acts 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-extended 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.

[0065] 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 removal of gaseous components such as NOx, HC, and CO using a catalyst, as well as the removal of particulate matter generated by the combustion of lubricating oil and fuel. These particulates include ash from the lubricating oil and fuel.

[0066] <About exhaust gas purification devices>

[0067] 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 2 A 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. Figure 7 This is a schematic diagram illustrating the four-point bending test method.

[0068] like Figure 2 As shown, the exhaust gas purification device 5 has a honeycomb structure 6 and a honeycomb filter 7.

[0069] The honeycomb structure 6 has a first honeycomb substrate 60. The first honeycomb substrate 60 has porous partitions 64 that divide a plurality of cells 63 extending from a first inflow side end face 61 to a first outflow side end face 62. The cells 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 cells 63 and is discharged from the first outflow side end face 62.

[0070] 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 cells 73 extending from a second inflow side end face 71 to a second outflow side end face 72. The sealing portion 75 seals the cells 73 at either the second inflow side end face 71 or the second outflow side end face 72. The cells 73 of the second honeycomb substrate 70 include a first cell 731 that opens at the second inflow side end face 71 and is sealed at the second outflow side end face 72, and a second cell 732 that opens at the second outflow side end face 72 and is sealed at 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 cell 731, passes through the partition wall 74 between the first cell 731 and the second cell 732, enters the second cell 732, and exits from the second outflow side end face 72.

[0071] The honeycomb filter 7 is positioned downstream of the honeycomb structure 6 in the exhaust system 4a of the vehicle 1 equipped with a gasoline engine, relative to the flow of exhaust gas 4b.

[0072] The honeycomb filter 7 is used to purify the exhaust gas 4b. As the exhaust gas 4b passes through the partition 74, the particles contained in the exhaust gas 4b are captured inside the honeycomb filter 7. That is, as a purification of the exhaust gas 4b, the honeycomb filter 7 at least removes particles.

[0073] The main component of the partition 74 of the honeycomb filter 7 is cordierite. Compared with other ceramics, cordierite has a low coefficient of thermal expansion and excellent thermal shock resistance. When it is mentioned that "the main component is cordierite", it means that it contains more than 90% cordierite by mass.

[0074] 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 gasket 95 (cushioning material). This gasket 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 gasket 95. This placement prevents movement of the honeycomb structure 6 and the honeycomb filter 7 within the tank 90, ensuring their stability within the tank 90. ​​The gasket 95 can be made of ceramic fiber or similar materials.

[0075] The cellular filter 7 can be in the first to third manner as shown below.

[0076] <Regarding the first method of cellular filter 7>

[0077] In the first embodiment, the opening ratio of the second honeycomb substrate 70 is 75% or higher. A ratio of 75% or higher ensures the accumulation volume of particles (ash) in the honeycomb filter 7 and reduces the heat capacity of the honeycomb filter 7, allowing it to heat up earlier. An opening ratio of 77% or higher is preferred. An opening ratio of 79% or lower is preferred. A ratio of 79% or lower maintains strength. The opening ratio of the second honeycomb substrate 70 is defined as the ratio of the area of ​​the perforated cells 73 in the total area of ​​the cross-section of the second honeycomb substrate 70 orthogonal to the axial direction at the axial center position. The opening ratio is determined 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 based on the shape of the second honeycomb substrate 70, ignoring the presence of the perforated cells 73. The area of ​​the perforated cells 73 is determined based on the shape of the partition wall 74, ignoring the presence of the catalyst supported on the partition wall 74. The opening ratio is determined by image analysis of the cross-section of the second honeycomb substrate 70.

[0078] The porosity of the partition wall 74 is 60% or higher. A porosity of 60% or higher helps to suppress the increase in pressure loss. Preferably, the porosity of the partition wall 74 is 62% or higher, more preferably 63% or higher. Preferably, the porosity of the partition wall 74 is 65% or lower. A porosity of 65% or lower reduces the possibility of the honeycomb filter 7 becoming brittle and easily detaching. The porosity of the partition wall 74 is a value measured using a mercury porosity meter.

[0079] When the honeycomb filter 7 is assembled into the exhaust gas purification device 5, a catalyst is supported on the partition wall 74. The catalyst can be a three-way catalyst. A three-way catalyst is a catalyst that primarily purifies hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). For example, catalysts containing platinum (Pt), palladium (Pd), and rhodium (Rh) can be cited. Through this three-way catalyst, hydrocarbons are purified into water and carbon dioxide, carbon monoxide is purified into carbon dioxide, and nitrogen oxides are purified into nitrogen by oxidation or reduction, respectively. The catalyst can be supported on the surface and within the pores of the partition wall 74. By supporting the catalyst on the partition wall 74, the honeycomb filter 7 also purifies gaseous components such as NOx, HC, and CO as part of the exhaust gas 4b.

[0080] The catalyst loading onto the partition wall 74 can be carried out under the following conditions. Specifically, the following method can be used: a catalyst main component, primarily composed of activated alumina and containing one or more noble metals selected from platinum, palladium, and rhodium within its pores, is mixed with catalyst promoters such as zirconium oxide or cerium oxide to form a slurry, thus obtaining a washcoat slurry. This washcoat slurry is then suctioned from either or both of the second inflow side end face 71 and the second outflow side end face 72 using a suction method, thereby loading the catalyst onto and within the partition wall 74. Drying is then performed at a temperature of 600°C, etc. However, this method is not limited to this. For example, the slurry composition may also contain other promoter components. The weight of the washcoat per unit filter volume after drying is typically 50 g / L to 150 g / L, but is not limited to this range; it is appropriately selected considering pressure drop, purification performance, and / or the filter strength after catalyst coating.

[0081] The average flexural strength at four points of the honeycomb filter 7 is 1.1 MPa or more when the partition wall 74 is not loaded with catalyst, or 1.5 MPa or more when the partition wall 74 is loaded with catalyst. The average flexural strength at four points of the second honeycomb substrate 70 varies depending on whether the partition wall 74 is loaded with catalyst. If the partition wall 74 of the honeycomb filter 7, which has an average flexural strength at four points of 1.1 MPa or more when the partition wall 74 is not loaded with catalyst, is loaded with catalyst, then the average flexural strength at four points of the honeycomb filter becomes 1.5 MPa or more. By ensuring that the average flexural strength at four points of the honeycomb filter meets the above conditions, the possibility of damage to the honeycomb filter 7 due to the surface pressure of the gasket 95 can be reduced.

[0082] The average bending strength at four points was determined according to JIS R1664 (2004). Specifically, a test piece TP with a thickness of 10 mm × width of 20 mm × length of 80 mm was cut from the honeycomb filter 7 in a manner where the length direction is aligned with the direction in which the perforations 73 extend (refer to...). Figure 7 ).like Figure 7 As shown, the test load is applied in the thickness direction of the test piece TP. Two cylindrical indenters 501 are positioned on the upper side of the test piece TP at a 20mm interval (distance between internal support points). Additionally, two cylindrical support platforms 502 are positioned on the lower side of the test piece TP at a 60mm interval (distance between external support points). Under these conditions, the load is applied equally to both indenters 501. The maximum load at which the test piece TP fails is measured at a load rate of 0.5~1mm / min.

[0083] The four-point bending strength of the test piece TP was determined based on JIS R1664 (2004) and calculated using the following formula.

[0084] σ=3P(Ll) / 2wt2

[0085] Here, σ is the four-point bending strength (MPa) of the test piece TP, P is the maximum load (N) at which the test piece TP fails, L is the distance between the external supports (mm), l is the distance between the internal supports (mm), w is the width (mm) of the test piece TP, and t is the thickness (mm) of the test piece TP. Then, a four-point bending test is performed on the minimum five test pieces TP, and the average of their four-point bending strengths is taken as the four-point average bending strength. As a bending test apparatus, the INSTRON 3366 double-column benchtop testing machine can be cited as an example.

[0086] The four-point mean bending strength of the honeycomb filter 7 in the state where the partition 74 is not loaded with catalyst was determined using a test piece TP cut from the honeycomb filter 7 in the state where the partition 74 is not loaded with catalyst. The four-point mean bending strength of the honeycomb filter 7 in the state where the partition 74 is loaded with catalyst was determined using a test piece TP cut from the honeycomb filter 7 in the state where the partition 74 is loaded with catalyst.

[0087] Preferably, the average flexural strength of the honeycomb filter 7 at four points is 1.2 MPa or more when the partition wall 74 is not loaded with catalyst, or at least 1.7 MPa or more when the partition wall 74 is loaded with catalyst. By ensuring that the average flexural strength of the honeycomb filter 7 at four points meets this condition, the possibility of damage to the honeycomb filter 7 due to the surface pressure of the gasket 95 can be reduced more reliably.

[0088] More preferably, the average flexural strength of the honeycomb filter 7 at four points is 1.5 MPa or more when the partition wall 74 is not loaded with catalyst, or at least 1.9 MPa or more when the partition wall 74 is loaded with catalyst. By ensuring that the average flexural strength of the honeycomb filter 7 at four points meets this condition, the possibility of damage to the honeycomb filter 7 due to the surface pressure of the gasket 95 can be reduced more reliably.

[0089] <Regarding the second method of cellular filter 7>

[0090] In the second method, the aperture ratio of the second honeycomb substrate 70 is 77% or higher. That is, the aperture ratio is higher than that of the first method. As a result, it is easier to ensure the ash accumulation volume, thus reducing the size of the honeycomb filter 7 and easily ensuring the mounting space.

[0091] The porosity of the partition wall 74 is 50% or more and 59% or less. With a porosity of 50% or more, the permeation pressure drop of the partition wall 74 can be suppressed, keeping the pressure drop of the honeycomb filter 7 within an acceptable range. With a porosity of 59% or less, the strength of the honeycomb filter 7 can be maintained even when set to a high porosity.

[0092] When the honeycomb filter 7 is assembled into the exhaust gas purification device 5, the catalyst is supported in the partition wall 74. The catalyst and its supporting conditions are the same as in the first method.

[0093] The average flexural strength of the honeycomb filter 7 at four points is 1.5 MPa or more when the partition wall 74 is not loaded with catalyst, or 1.8 MPa or more when the partition wall 74 is loaded with catalyst. The method for measuring the average flexural strength at four points is the same as in the first embodiment. The average flexural strength at four points of the honeycomb filter 7 in the second embodiment is higher than that in the first embodiment. This is because, in the second embodiment, a region with a lower porosity as the partition wall 74 is selected. That is, by ensuring that the average flexural strength at four points of the honeycomb filter 7 meets the above conditions, even if the opening ratio is higher than in the first embodiment, the possibility of damage to the honeycomb filter 7 due to the surface pressure of the gasket 95 can be reduced.

[0094] <Regarding the third method of cellular filter 7>

[0095] In the third embodiment, the opening ratio of the second honeycomb substrate 70 is 75% or more, similar to the first embodiment. The porosity of the partition wall 74 is 50% or more and 59% or less, similar to the second embodiment. Furthermore, the honeycomb filter 7 does not carry a catalyst in the partition wall 74 when assembled into the exhaust gas purification device 5. The average flexural strength at four points of the honeycomb filter 7 in the state where the partition wall 74 is not carrying a catalyst is 1.5 MPa or more. Thus, for the honeycomb filter 7 used in the state where the partition wall 74 is not carrying a catalyst, by ensuring that the average flexural strength at four points of the honeycomb filter 7 meets the above condition, the possibility of damage to the honeycomb filter 7 due to the surface pressure of the gasket 95 can also be reduced.

[0096] <Regarding the overall view of the honeycomb filter 7>

[0097] Overall, when considering the honeycomb filter 7 of the first to third types described above, the honeycomb filter 7 of this embodiment is a wall-flow type honeycomb filter 7 in which a catalyst is supported or not supported in the partition wall 74 when assembled in the exhaust gas purification device 5. The main component of the partition wall 74 is cordierite, the opening ratio of the second honeycomb substrate 70 is 75% or more, and the average bending strength of the honeycomb filter 7 at four points in the state of being assembled in the exhaust gas purification device 5 is 1.5 MPa or more.

[0098] <Preferred configuration of the first to third type cellular filter 7>

[0099] The average isostatic pressure of the honeycomb filter 7 is preferably 1.2 MPa or higher. By having an isostatic pressure of 1.2 MPa or higher, when the filter is fixed within the tank 90 (metal tank) by a gasket 95 made of compressed ceramic fibers, damage due to surface pressure of the gasket 95 can be avoided. Isostatic pressure is the destructive strength measured by applying hydrostatic pressure in water. The honeycomb filter 7 is held in place by plates protecting the second inflow end face 71 and the second outflow end face 72. The entire honeycomb filter 7 is placed in a rubber container and inserted into a hydrostatic pressure tank. The hydrostatic pressure inside the tank is gradually increased, and the hydrostatic pressure at the moment of detection of the destructive sound is taken as the isostatic pressure strength. The isostatic pressure strength is measured for at least three test specimens, and their average value is taken as the average isostatic pressure strength.

[0100] Preferably, the partitions 74 of the honeycomb filter 7 contain 1% or more of any one of cerium, zirconium, and titanium. Generally, based on the idea that a lower coefficient of thermal expansion results in better thermal shock resistance, the aim is to minimize the number of glass layers. However, fewer glass layers may reduce strength, and the range of pore structure and porosity of the partitions 74 is also limited. Therefore, it has been found that during the manufacturing stage of the honeycomb filter 7, any one of cerium, zirconium, and titanium is intentionally used as a sintering aid to form the glass layers. The glass layers are preferentially used to fill the intergranular spaces and microcracks of cordierite, thereby improving strength. This allows for strength even with high porosity and high opening ratio, which is effective for achieving the temperature rise characteristics required in electric vehicles. As described above, by containing 1% or more of any one of cerium, zirconium, and titanium, strength can be more reliably ensured even with high porosity and high opening ratio. It is sufficient to contain 1% or more of any one of cerium, zirconium, and titanium, or 1% or more of each of two or three.

[0101] The average coefficient of thermal expansion of the honeycomb filter 7 along the extension direction of the perforation 73 is preferably 1.2 ppm / K (=1.2×10⁻⁶) at temperatures ranging from 40°C to 800°C. -6 (1 / K) or higher. With a concentration of 1.2ppm / K or higher, the thermal expansion difference between the honeycomb filter 7 and the tank 90 can be reduced, and the holding force can be prevented from decreasing at high temperatures and the honeycomb filter 7 from moving due to vibration and pressure.

[0102] The average coefficient of thermal expansion was determined according to JIS R1618 (2002). Specifically, similar to the four-point bending test described above, test pieces with a width of 10 mm × length of 20 mm × thickness of 80 mm were cut from the honeycomb filter 7 with the thickness direction aligned with the direction of the extension of the pores 73. Then, the value obtained by dividing the change in length of the test piece TP when the temperature changes from 40°C to 800°C by the length of the test piece at 40°C was taken as the coefficient of thermal expansion. The coefficient of thermal expansion was measured for at least two test pieces, and their average value was taken as the average coefficient of thermal expansion.

[0103] The preferred honeycomb filter 7 has a glass layer 74 comprising any one of cerium, zirconium, and titanium, with the glass layer accounting for more than 3% of its weight. By ensuring that the weight ratio of the glass layer exceeds 3%, strength can be reliably guaranteed even with high porosity and high opening ratio. The amount (by weight) of cordierite crystals is determined by X-ray crystallography of the second honeycomb substrate 70 without a catalyst, and the remainder is considered as the weight of the glass layer. The weight ratio of the glass layer is obtained by dividing the weight of the glass layer by the total weight of the filter substrate. The weight ratio of the glass layer is more preferably 5% or more. From the viewpoint of chemical stability against acids and alkalis contained in engine exhaust gases, the weight ratio of the glass layer is more preferably 10% or less.

[0104] The following provides a more detailed description of the honeycomb structure 6 and the honeycomb filter 7.

[0105] <About honeycomb structures>

[0106] A three-way catalyst can be supported on the honeycomb structure 6 (first honeycomb substrate 60). 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). Using this three-way catalyst, hydrocarbons are purified into water and carbon dioxide through oxidation or reduction, carbon monoxide is purified into carbon dioxide, and nitrogen oxides are purified into nitrogen.

[0107] like Figure 2As shown, in the honeycomb structure 6, the first honeycomb substrate 60 has a honeycomb shape with porous partitions 64. These partitions 64 are divided into multiple cells 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 cells 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 cells 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, the loading per unit volume of the three-way catalyst can be increased. It should be noted that in the honeycomb structure 6, the loading per unit volume of the three-way catalyst can be uniform, but it is preferable that the loading per unit volume of the three-way catalyst loaded at the end on the first inflow side end face 61 is greater than the loading of the three-way catalyst loaded in 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 large amount of 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 the range from the first inflow side end face 61 to a position where the distance from the first inflow side end face 61 is 10% to 60% of the length in the direction of the central axis of the honeycomb structure 6.

[0108] The shape of the honeycomb structure 6 is not limited to Figure 4 The cylindrical shape shown can be exemplified by elliptical cylindrical shapes, square cylindrical shapes, and cylindrical shapes with polygonal bases, as well as cylindrical shapes with irregular bases.

[0109] Specifically, the honeycomb structure 6 is preferably 30-200 mm in length along its central axis.

[0110] 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 that of the honeycomb filter 7, the honeycomb structure 6 is 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 that of the honeycomb filter 7. Therefore, the heating rate is faster, and the honeycomb structure 6 can easily reach the catalyst activation temperature in the earlier 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, exhaust particulate matter in the exhaust gas 4b can be removed more efficiently.

[0111] 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 50-80% of the diameter of the honeycomb filter 7, more preferably 55-75%, and even more preferably 60-70%. 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%, even using the heat of the exhaust gas 4b, the honeycomb structure 6 may not be able to heat up sufficiently (the heating rate becomes slower). Furthermore, for example, when the honeycomb structure 6 is cylindrical, the diameter of its bottom surface is preferably 80-180 mm. When the honeycomb structure 6 is not 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.

[0112] The thickness of the partition wall 64 is preferably 50.8 to 101.6 μm, more preferably 50.8 to 75 μm, and particularly preferably 65 to 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 pores 63 may increase. The thickness of the partition wall 64 is determined by microscopic observation of a cross-section parallel to the central axis.

[0113] The porosity of the partitions 64 of the honeycomb structure 6 can be above 35% and below 70%. A porosity of 35% or more reduces heat capacity and shortens heating time, thus suppressing increased pressure loss. A porosity of 70% or less reduces the likelihood of the honeycomb structure 6 becoming brittle and easily detaching. The porosity is a value measured using a mercury porosity meter.

[0114] The pore density of the honeycomb structure 6 (i.e., the pore density of a cross section orthogonal to the central axis of the first honeycomb substrate 60) can be greater than that 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 that of the second honeycomb substrate 70 of the honeycomb filter 7. With such a higher pore 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. Consequently, the honeycomb structure 6 can more easily reach the catalyst activation temperature in the earlier stages after engine start-up.

[0115] Specifically, the preferred pore density of the honeycomb structure 6 is 32 to 186 pores / cm². 2 More preferably, 40~100 per cm 2 Ideally, the number of particles per cm should be 50-60. 2 If within the above range, the contact area between exhaust gas 4b and honeycomb structure 6 increases, and honeycomb structure 6 easily reaches the catalyst activation temperature in the earlier stages after engine start-up. If it is less than 32 cells / cm²... 2 If this occurs, the strength of the honeycomb structure 6 may decrease. On the other hand, if it exceeds 186 cells / cm²... 2 If this happens, the pressure loss may increase.

[0116] The opening ratio of the first honeycomb substrate 60 of the honeycomb structure 6 can be larger than that of the second honeycomb substrate 70 of the honeycomb filter 7. However, in such cases, it is preferable that the porosity of the partition walls 64 of the first honeycomb substrate 60 is smaller than that of the partition walls 74 of the second honeycomb substrate 70. If the porosity of the partition walls 64 is smaller than that of the partition walls 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 larger than that of the second honeycomb substrate 70 of the honeycomb filter 7, the heat capacity of the honeycomb structure 6 is smaller 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 walls 64 is preferably smaller than that of the partition walls 74. Furthermore, since the honeycomb structure 6 heats up in an earlier 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.

[0117] The ratio of the length of the central axis of the honeycomb structure 6 to the diameter of the first inflow side end face 61 is preferably 0.1 to 0.4, more preferably 0.15 to 0.35, and particularly preferably 0.2 to 0.3. If it is less than 0.1, the time that the exhaust gas 4b remains in the first honeycomb substrate 60 (honeycomb structure 6) becomes shorter. Therefore, the honeycomb structure 6 will not be sufficiently heated by the heat of the exhaust gas 4b, and it may not be able to fully obtain the purification performance after the engine is started. On the other hand, if it exceeds 0.4, the honeycomb structure 6 becomes too heavy (the density becomes too high), and therefore cannot be sufficiently heated by the heat of the exhaust gas 4b, and it may not be able to fully obtain the purification performance of the exhaust gas 4b.

[0118] 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 a 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.

[0119] The shape of the cells 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. Other irregular shapes are also acceptable. A combination of quadrilaterals and octagons is also a preferred option.

[0120] Furthermore, the hydraulic diameters of all the cells in the honeycomb structure 6 can be the same, and the hydraulic diameters of the cells 63 opening on the first inflow side end face 61 and the cells 63 opening on 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 cells 63 opening on the first outflow side end face 62 is larger than the hydraulic diameter of the cells 63 opening on the first inflow side end face 61, and preferably that the hydraulic diameter of the cells 63 opening on the first inflow side end face 61 is 20-45% of the hydraulic diameter of the cells 63 opening on the first outflow side end face 62. In this specification, the "hydraulic diameter of the cell" is a value calculated using the formula "4 × (cross-sectional area) / (perimeter)". Here, "cross-sectional area" refers to the area of ​​the cells in a section orthogonal to the direction of cell extension, and "perimeter" refers to the "length of the outer perimeter of the cells" in a section orthogonal to the direction of cell extension.

[0121] 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 of the following groups: 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, when referring to "primarily composed of ceramic," it means containing at least 90% ceramic by mass.

[0122] 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.

[0123] 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 start-up. If it exceeds 400 g / L, the loading per unit volume is too large, narrowing the flow path of the pores 63 with openings at both ends, which may increase pressure loss.

[0124] <About Cellular Filters>

[0125] like Figure 2 As shown, in the honeycomb filter 7, the second honeycomb substrate 70 has a honeycomb shape with porous partitions 74, which are divided into multiple pores 73 that extend from the second inflow side end face 71 to the second outflow side end face 72 to form a flow path for the fluid. 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, square cylindrical shapes, and cylindrical shapes with polygonal bases, as well as cylindrical shapes with irregular bases.

[0126] 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, if the honeycomb filter 7 is cylindrical, its bottom diameter is preferably 80 to 180 mm. If 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.

[0127] The thickness of the partition wall 74 is preferably 127-508 μm, more preferably 200-400 μm, and particularly preferably 250-350 μm. If it is less than 127 μm, the strength of the honeycomb filter 7 may decrease. On the other hand, if it exceeds 508 μm, the pressure loss when the exhaust gas 4b passes through the pores 73 may increase. The thickness of the partition wall 74 is determined by microscopic observation of a cross-section parallel to the central axis.

[0128] The pore density of the honeycomb filter 7 (i.e., the pore density of the cross section orthogonal to the central axis of the second honeycomb substrate 70) is preferably 7.7 to 46.5 pores / cm². 2 More preferably, 10~40 per cm 2 The preferred size is 15-25 per cm. 2 If less than 7.7 per cm 2 If the strength of the honeycomb filter 7 is reduced, then the strength of the filter may decrease. On the other hand, if it exceeds 46.5 cells / cm²... 2 If this happens, the pressure loss may increase.

[0129] The ratio of the length of the honeycomb filter 7 along its central axis to the diameter of the second inflow side end face 71 is preferably 0.5 to 1.5, more preferably 0.8 to 1.5, and particularly preferably 1.1 to 1.3. If it is less than 0.5, the length of the second honeycomb substrate 70 along its central axis becomes too short, thus reducing the filtration area and deteriorating the collection efficiency; furthermore, the pressure loss may increase. On the other hand, if it exceeds 1.5, the length of the second honeycomb substrate 70 along its central axis becomes too long, thus increasing the pressure loss within the pore flow path; therefore, the overall pressure loss of the honeycomb filter 7 may become excessive.

[0130] The average pore size of the partition wall 74 is preferably 7 to 40 μm, more preferably 8 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 particulate matter collection performance may decrease. The average pore size of the partition wall 74 is a value measured with a mercury porosity meter.

[0131] The shape of the pores 73 in the honeycomb filter 7 is not particularly limited. In a cross-section orthogonal to the central axis, polygons such as triangles, quadrilaterals, pentagons, hexagons, and octagons, circles, or ellipses are preferred, but other irregular shapes are also acceptable. 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 pores 73 extend, all the cross-sectional areas of the pores 73 are the same, but the cross-sectional area of ​​the second pore 732 with a 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 pores 73 extend) is smaller than the cross-sectional area of ​​the first pore 731 with a 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 pores 73 extend). If this is the case, the increase in pressure loss when capturing particulate matter in the exhaust gas 4b can be suppressed.

[0132] Furthermore, the hydraulic diameters of all cells in the second honeycomb substrate 70 can be the same, and the hydraulic diameters of the first cell 731 and the second cell 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 cell 732 is larger than that of the first cell 731, and preferably the hydraulic diameter of the first cell 731 is 20 to 45% of the hydraulic diameter of the second cell 732.

[0133] 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 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 filter 7. Alternatively, if the outer peripheral wall is a cement-coated wall, materials containing flux components such as glass incorporated into the matrix can be used as the material for the cement-coated wall. Furthermore, the thickness of the outer peripheral wall is preferably 0.5 to 1.5 mm.

[0134] 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 when using 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 active 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.

[0135] 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.

[0136] 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.

[0137] The sealing section 75 is preferably configured to alternately seal the first hole grid 731 and the second hole grid 732 so that the two end faces have a square pattern.

[0138] 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 area of ​​PM capture by 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 in which the pore grid 73 extends.

[0139] The canister 90 is not particularly limited and can be any canister commonly used for purifying ceramic honeycomb filters, such as those used for automobile exhaust. Examples of materials for the canister 90 include ferrite-based 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 preferably used for the canister 90.

[0140] 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 partitions 96 and the like between them. For example, stainless steel or other metals can be used as the material for partitions 96.

[0141] <Manufacturing Method of Waste Gas Purification Device>

[0142] 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.

[0143] The manufacturing method comprises the following steps:

[0144] In the honeycomb structure forming process, a first honeycomb molded body is fired to obtain a first honeycomb substrate. The first honeycomb molded body has a porous partition wall that divides multiple pores to form a flow path for the fluid from the first inflow side end face to the first outflow side end face. A catalyst slurry containing a ternary catalyst is flowed into the multiple pores from the first inflow side end face of the first honeycomb substrate. The catalyst slurry (supporting the ternary catalyst) is coated on the partition wall surface of the multiple pores to form a honeycomb structure.

[0145] In the honeycomb filter forming process, a second honeycomb molded body having multiple porous partitions dividing a flow path from a second inflow side end face to a second outflow side end face and forming a flow path for fluid is sealed at the openings of predetermined cells on one end face and the openings of remaining cells on the other end face. The body is then fired to form a honeycomb filter having a second honeycomb substrate, wherein the openings of predetermined cells on the second inflow side end face and the openings of remaining cells on the second outflow side end face of the second honeycomb substrate are sealed.

[0146] In the assembly process, a honeycomb structure is arranged on the inlet side of the tank, which has an inlet for waste gas to flow in and an outlet for purified waste gas to flow out, with the first inlet-side end face facing the inlet side of the tank. Furthermore, a honeycomb filter is arranged on the outlet side of the tank, with the second outlet-side end face facing the outlet side of the tank, thereby housing the honeycomb structure and the honeycomb filter within the tank.

[0147] As a honeycomb structure formed in the honeycomb structure forming process, the ratio of the length of the honeycomb structure in the central axis direction to the length of the honeycomb filter in the central axis direction is 0.1 to 0.5. The pore density of the first honeycomb substrate constituting the honeycomb structure is greater than the pore density of the second honeycomb substrate constituting 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. The diameter of the honeycomb structure is the same as or smaller than the diameter of the honeycomb filter. As a honeycomb filter formed in the honeycomb filter forming process, it does not support a catalyst, or it supports a catalyst and the catalyst loading per unit volume is less than the catalyst loading per unit volume of the ternary catalyst supported in the honeycomb structure. Through the above processes, the exhaust gas purification device of this utility model can be manufactured.

[0148] <About the honeycomb structure formation process>

[0149] 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 molded 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.

[0150] The preferred molding raw 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.

[0151] As a ceramic raw material, it is preferably selected from at least one of the following groups: 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 molding raw material is preferably 80-95% by mass.

[0152] Examples of organic binders include methylcellulose, hydroxypropyl methylcellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol. Among these, methylcellulose and hydroxypropyl methylcellulose are preferred in combination. The binder content relative to the total molding raw material is preferably 1-10% by mass. One type can be used alone, or two or more can be used in combination.

[0153] 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. One type can be used alone, or two or more can be used in combination.

[0154] Surfactants such as ethylene glycol, dextrin, fatty acid soaps, and polyols can be used. They can be used individually or in combination of two or more. The surfactant content relative to the total molding raw material is preferably 0.1-5% by mass.

[0155] The content of the dispersion medium is preferably 0.1 to 5% by mass relative to the total mass of the molding raw material.

[0156] 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.

[0157] There are no particular limitations on the method of 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 pore shape, septum thickness, and pore density. As for the die material, a wear-resistant, ultra-hard alloy is preferred.

[0158] 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 1380~1450℃, more preferably 1400~1440℃. In addition, the firing time is preferably set to about 3~10 hours.

[0159] It should be noted that the first honeycomb molded body can also 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.

[0160] Next, the method for coating the catalyst slurry (supported by a 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 pores by impregnation or suction. Preferably, the catalyst slurry is coated on the entire surface of the partition walls within the pores. Then, after the catalyst slurry has poured into the pores, the remaining slurry is blown away with compressed air. Then, by drying and sintering the catalyst slurry, a honeycomb structure with the three-way catalyst supported on the surface of the partition walls within the pores can be obtained. The drying conditions are preferably set at 80~150°C for 1~6 hours. The sintering 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.

[0161] <About the honeycomb filter forming process>

[0162] The second honeycomb molded body used in the honeycomb filter forming process can be manufactured as follows: The clay is extruded and molded into a honeycomb shape in a manner that meets the following conditions to obtain the second honeycomb molded body.

[0163] In this extrusion molding process, the blank extruded from the die is cut such that the ratio of the length of the honeycomb structure along its central axis to the length of the honeycomb filter along its central axis is 0.1 to 0.5. Furthermore, a die is used in which the pore density of the first honeycomb substrate of the honeycomb structure is greater than that of the second honeycomb substrate of the honeycomb filter, the opening ratio of the first honeycomb substrate of the honeycomb structure is greater than that 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.

[0164] One method for sealing the openings of the cells 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 cells. Here, the method of applying the mask is not particularly limited, but it is preferable to alternately seal the openings of predetermined cells in the second outflow side end face and the remaining openings of cells in the second inflow side end face of the second honeycomb substrate, applying 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 pre-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 hydroxypropyl methylcellulose and methylcellulose. Then, the end with the mask applied is immersed in a storage container, and sealing material is filled into the openings of the unmasked pores to form a sealed portion. The viscosity of the sealing material is preferably 600~1200 Pa·s. It should be noted that the viscosity of the sealing material is a value measured at 30°C using a rotary viscometer at a rotational speed of 30 rpm.

[0165] Then, a mask is applied to the other end face of the second honeycomb molded body to block the openings of the remaining cells. Next, the masked other 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 cells to form sealing portions. In this way, a honeycomb filter molded body can be obtained in which the openings of predetermined cells on one end face of the second honeycomb molded body and the openings of the remaining cells on the other end face are equipped with sealing portions.

[0166] 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 1380~1450℃, more preferably 1400~1440℃. In addition, the firing time is preferably set to about 3~10 hours.

[0167] It should be noted that the honeycomb filter molded body can also 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.

[0168] It should be noted that, before the second honeycomb molded body forms the sealing portion, the second honeycomb molded body can also be fired to obtain a honeycomb fired body. The opening of the predetermined cell in one end face and the opening of the remaining cell in the other end face of the obtained honeycomb fired body are formed into a sealing portion, and then further fired to obtain a honeycomb filter.

[0169] It should be noted that a honeycomb filter can be obtained by coating a honeycomb filter structure with a catalyst slurry (catalyst-supported) 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 flowed into the pores by impregnation and suction. Preferably, the catalyst slurry is coated on the entire surface of the partition walls within the pores. After the catalyst slurry has flowed into the pores, any remaining slurry is blown away with compressed air. Then, by drying and sintering the catalyst slurry, a sealed honeycomb structure with the catalyst supported on the surface of the partition walls within the pores can be obtained. The drying conditions are preferably set at 80–150°C for 1–6 hours. The sintering 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 as examples.

[0170] <About the assembly process>

[0171] During the assembly process, the outer periphery of the honeycomb structure and the honeycomb filter are covered with gaskets (cushioning material), and then the honeycomb structure and the honeycomb filter, covered with gaskets, are placed inside the tank. At this time, it is preferable that the honeycomb structure and the honeycomb filter are housed in a compressed state within the tank. Examples of gaskets include ceramic fiber gaskets. This prevents the honeycomb structure and the honeycomb filter from moving within the tank.

[0172] The tank body can use conventionally known tank bodies, for example, it can be manufactured by stamping and welding sheet material made of ferrite-based 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.

[0173] 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 general knowledge in the technical field to which this invention pertains can conceive of various modifications or alterations within the scope of the technical concept described in the claims, and these modifications are naturally understood to fall within the technical scope of this invention.

[0174] Example

[0175] The present invention will be described in more detail below through embodiments. The present invention is not limited to these embodiments.

[0176] (Example 1)

[0177] [Fabrication of Honeycomb Structures] (Honeycomb Structure Formation Process)

[0178] First, as raw materials for cordierite petrochemicals, alumina, aluminum hydroxide, kaolin, talc, and silica are used. 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 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.

[0179] Next, the clay is extruded using a predetermined mold to form a honeycomb molded body with quadrilateral pores 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. Then, the honeycomb molded body is dried using a hot air dryer, and further fired at 1410~1440℃ for 5 hours to obtain a dried honeycomb body.

[0180] 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 fine 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 dry body was impregnated with the obtained coating slurry. Then, with the inflow-side end impregnated, the coating slurry was vacuum-suctioned from the outflow-side end face of the honeycomb dry body, thereby coating the slurry onto the partition wall of the honeycomb dry body to form a catalyst layer. Then, it was dried and calcined at 600°C for 3 hours to produce a honeycomb structure.

[0181] 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 140 cells / cm². 2 (900cpsi), the opening ratio of the first honeycomb substrate is 88%, the porosity of the partition is 55.0%, and the loading of the three-way catalyst is 150g / L.

[0182] It should be noted that the catalyst supported on the honeycomb structure is supported on oxides (γAl₂O₃ and CeO₂) at a Pt loading of 1 g / L per unit volume of the honeycomb catalyst body, and the Rh loading is 0.2 g / L per unit volume of the 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.

[0183] [Cellular Filter Fabrication] (Cellular Filter Formation Process)

[0184] First, 100 parts by weight of cordierite raw materials using alumina, aluminum hydroxide, kaolin, talc, and silica as cordierite raw materials and 0-5 wt% cerium oxide as a sintering aid are mixed and kneaded to prepare blanks. 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.

[0185] Next, the clay is extruded and shaped using a pre-designed mold to obtain a honeycomb structure with quadrilateral pores and a cylindrical overall shape.

[0186] 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 mask is applied to the openings of a portion of the cells on one end face of the honeycomb molded body. The masked end is then immersed in a sealing slurry containing cordierite. For the other end, a mask is applied to the openings of a portion of the cells sealed at the aforementioned end. Then, by immersing the end face in the sealing slurry, the sealing slurry is filled into the openings of the predetermined cells on one end face in a grid pattern, alternating between the openings of the predetermined cells on one end face and the openings of the remaining cells 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.

[0187] 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 0.14 mm, and a pore density of 65 pores / cm². 2 (420cpsi), the pore spacing is 1.24mm, the opening rate of the second honeycomb substrate is 79%, the porosity of the partition is 65.0%, the loading of the three-way catalyst is 80g / L, and the cerium content in the partition is 3w.

[0188] For the fabricated honeycomb filter, the average coefficient of thermal expansion (ppm / K), the weight ratio of the glass layer set in the partition (%), the average isostatic compressive strength (MPa), and the four-point flexural strength (MPa) before and after catalyst coating were investigated.

[0189] [Method for determining the average coefficient of thermal expansion]

[0190] The average coefficient of thermal expansion was determined according to JIS R1618 (2002). Test pieces with a width of 10 mm × a length of 20 mm × a thickness of 80 mm were cut from the honeycomb filter with the thickness direction aligned with the direction of the pore extension. The coefficient of thermal expansion was obtained by dividing the change in length of the test piece when its temperature changed from 40°C to 800°C by the length of the test piece at 40°C. The coefficients of thermal expansion were measured for two test pieces, and their average value was taken as the average coefficient of thermal expansion.

[0191] [Method for determining the weight ratio of the glass layer]

[0192] The amount (by weight) of cordierite crystals was determined by X-ray crystallography of the cell substrate of the catalyst-free cell filter, and all other components were considered as the weight of the glass layer. The weight of the glass layer was then divided by the total weight of the cell substrate of the cell filter to obtain the weight ratio of the glass layer.

[0193] [Method for determining mean isostatic strength]

[0194] The honeycomb filter is clamped between plates protecting the inflow and outflow ends. The entire honeycomb filter is placed into a rubber container and inserted into a hydrostatic pressure tank. The hydrostatic pressure inside the tank is gradually increased, and the hydrostatic pressure at the moment of detection of the destructive sound is taken as the isostatic strength. The isostatic strength is measured on three test specimens, and their average value is taken as the average isostatic strength.

[0195] [Method for determining the average bending strength at four points]

[0196] The average bending strength at four points was determined according to JIS R1664 (2004). Specifically, test pieces with a width of 20 mm × thickness of 10 mm × length of 80 mm were cut from the honeycomb filter before and after catalyst coating, with the length direction aligned with the pore extension direction. Figure 7 As shown, the test load is applied in the thickness direction of the test piece (the direction of the pore extension). Two cylindrical indenters are positioned 20 mm apart on the upper side of the test piece (distance between internal support points), and two cylindrical support platforms are positioned 60 mm apart on the lower side of the test piece (distance between external support points). Under these conditions, the load is applied equally to both indenters. The load is applied at a rate of 0.5–1 mm / min, and the maximum load at which the test piece fails is measured. Then, the four-point bending strength of the test piece TP is calculated based on the following formula.

[0197] σ=3P(Ll) / 2wt 2

[0198] Here, σ is the four-point bending strength (MPa) of the test piece TP, P is the maximum load (N) at which the test piece fails, L is the distance between the external supports (mm), l is the distance between the internal supports (mm), w is the width of the test piece (mm), and t is the thickness of the test piece (mm). Then, four-point bending tests were performed on five test pieces TP, and the average of their four-point bending strengths was taken as the four-point average bending strength. An INSTRON 3366 dual-column benchtop testing machine was used as the bending testing apparatus.

[0199] 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 partitions. During installation, gaskets primarily composed of ceramic fibers are 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 by partitions with a 50mm distance between their end faces (between the first outflow side end face and the second inflow side end face). This device is then installed in an exhaust system with a 2000cm³ exhaust volume. 3An exhaust system for a gasoline engine of an extended-range EV (REEV) vehicle, wherein the gasoline engine is used as a power source for power generation, a motor with an output of 60kW is provided as a power source for the vehicle, and a battery with a capacity of 50kWh is provided.

[0200] For the produced exhaust gas purifying device, the retention performance, purification performance and battery space guarantee are evaluated by the following methods.

[0201] [Evaluation Method for Retention Performance]

[0202] The retention performance is evaluated by the following method: in a canned state where the device is fixed in a metal can by surface pressure via a ceramic fiber gasket in the same form as when it is mounted on a vehicle, vibration is applied by an exciter while high-temperature gas generated by a propane gas burner flows. Temperature cycles of 100°C and 800°C, each for 10 minutes, are repeated, and after implementing an 8-hour test where a 30G vibration is applied along the axial direction of the filter, the result is rated "Excellent" when the displacement of the honeycomb filter is less than 0.2mm, "Good" when the displacement is less than 0.5mm, "Acceptable" when the displacement is less than 2mm, and "Unacceptable" when the displacement exceeds 2mm. Ratings from "Excellent" to "Acceptable" are determined as qualified.

[0203] [Evaluation Method for Purification Performance]

[0204] Purification performance is evaluated by measuring emissions of a vehicle on a chassis dynamometer during operation in WLTC mode. The result is rated "Excellent" when the NOX+HC emission value is less than 20mg / km, "Good" when the emission value is less than 50mg / km, "Acceptable" when the emission value is less than 60mg / km, and "Unacceptable" when the emission value exceeds 60mg / km. Ratings from "Excellent" to "Acceptable" are determined as qualified.

[0205] [Evaluation Method for Battery Space Guarantee]

[0206] Battery space guarantee is evaluated based on the length of the honeycomb filter. The result is rated "Good" when the length of the honeycomb filter is 80mm or less, "Acceptable" when the length is 120mm or less, and "Unacceptable" when the length exceeds 120mm. Ratings from "Good" to "Acceptable" are determined as qualified.

[0207] In the following table, for comprehensive judgment, "Good" means there are no "Acceptable" or "Unacceptable" ratings in the above evaluation results, "Acceptable" means there are only "Acceptable" or "Good" ratings, and "Unqualified" means there is at least one "Unacceptable" rating.

[0208] In the following examples and comparative examples, honeycomb structures under the same conditions as those in Example 1 are used. The honeycomb filter will be described with respect to the following modified parts.

[0209] (Example 2)

[0210] Example 2 is the same as Example 1 except that the porosity is changed to 63% and the Ce content is changed to 2%.

[0211] (Example 3)

[0212] Example 3 is the same as Example 1 except that the porosity is changed to 60% and the Ce content is changed to 1%.

[0213] (Example 4)

[0214] Example 4 is the same as Example 1 except that the porosity is changed to 62% and the Ce content is changed to 0.5%.

[0215] (Example 5)

[0216] Example 5 is the same as Example 3 except that the length of the honeycomb filter is changed to 110 mm, the thickness of the partition is changed to 0.15 mm, and the porosity is changed to 62%.

[0217] (Example 6)

[0218] Example 6, except that the pore density was changed to 62 pores / cm 2 Except for that, it is the same as in Example 5.

[0219] (Example 7)

[0220] Example 7 is the same as Example 5 except that the length of the honeycomb filter is changed to 120 mm and the thickness of the partition is changed to 0.14 mm.

[0221] (Example 8)

[0222] Example 8 changed the pore density to 56 pores / cm² 2 Except for changing the thickness of the partition to 0.15mm, it is the same as in Example 1.

[0223] (Example 9)

[0224] Example 9 is the same as Example 8 except that the Ce content is changed to 2%.

[0225] (Example 10)

[0226] Example 10 is the same as Example 8 except that the Ce content is changed to 1%.

[0227] (Example 11)

[0228] Example 11 is the same as Example 8 except that the Ce content is changed to 0.5%.

[0229] (Example 12)

[0230] Example 12 changed the pore density to 53 pores / cm² 2 Except for changing the thickness of the partition to 0.17 mm, it is the same as in Example 5.

[0231] (Example 13)

[0232] Example 13 is the same as Example 7 except that the thickness of the partition is changed to 0.18 mm.

[0233] (Example 14)

[0234] Example 14 changed the thickness of the partition wall to 0.15 mm and the pore density to 56 pores / cm². 2 Except for changing the porosity to 62%, it is the same as in Example 1.

[0235] (Example 15)

[0236] Example 15 is the same as Example 14 except that the porosity is changed to 63%.

[0237] (Example 16)

[0238] Example 16 is the same as Example 14 except that the porosity is changed to 64%.

[0239] (Example 17)

[0240] Example 17 is the same as Example 4 except that the porosity is changed to 59%.

[0241] (Example 18)

[0242] Example 18 is the same as Example 7 except that the porosity is changed to 53%.

[0243] (Example 19)

[0244] Example 19, except that the pore density was changed to 62 pores / cm² 2 Except for changing the usage conditions to non-coating (without catalyst support), it is the same as in Example 18.

[0245] (Example 20)

[0246] Example 20 is the same as Example 18 except that the length of the honeycomb filter is changed to 120 mm and the usage conditions are changed to uncoated.

[0247] (Example 21)

[0248] Example 21 changed the length of the honeycomb filter to 80mm and the pore density to 56 pores / cm². 2 Except for that, it is the same as in Example 19.

[0249] (Example 22)

[0250] Example 22 changed the thickness of the partition wall to 0.17 mm and the pore density to 53 pores / cm². 2 Except for that, it is the same as in Example 19.

[0251] (Example 23)

[0252] Example 23 changed the thickness of the partition wall to 0.18 mm and the pore density to 56 pores / cm². 2 Except for that, it is the same as in Example 20.

[0253] (Example 23)

[0254] Example 23, except that the pore density was changed to 56 pores / cm² 2 Except for changing the thickness of the partition to 0.18 mm, it is the same as in Example 20.

[0255] (Example 24)

[0256] Example 24 is the same as Example 23 except that the length of the honeycomb filter is changed to 75 mm, the thickness of the partition is changed to 0.08 mm, and the Ce content is changed to 3%.

[0257] (Example 25)

[0258] Example 25 is the same as Example 24 except that the thickness of the partition is changed to 0.1 mm.

[0259] (Example 26)

[0260] Example 26 is the same as Example 25 except that the length of the honeycomb filter is changed to 90 mm and the thickness of the partition is changed to 0.14 mm.

[0261] (Example 27)

[0262] Example 27 is the same as Example 26 except that the thickness of the partition wall is changed to 0.15 mm, the amount of catalyst is changed to 80 g / L, and the Ce content is changed to 0 g / L.

[0263] (Example 28)

[0264] Example 28 is the same as Example 27 except that the length of the honeycomb filter is changed to 85 mm and the application conditions are changed to uncoated catalyst.

[0265] (Example 29)

[0266] Example 29 is the same as Example 28 except that the thickness of the partition is changed to 0.14 mm.

[0267] (Example 30)

[0268] Example 30 is the same as Example 27 except that the thickness of the partition wall is changed to 0.09 mm and the porosity is changed to 50%.

[0269] (Example 31)

[0270] Example 31 is the same as Example 17 except that the usage conditions are changed to non-coated catalyst.

[0271] (Example 32)

[0272] Example 32 is the same as Example 24 except that the thickness of the partition wall is changed to 0.1 mm and the amount of catalyst is changed to 80 g / L.

[0273] (Example 33)

[0274] Example 33 is the same as Example 26 except that the catalyst amount is changed to 80 g / L.

[0275] (Comparative Example 1)

[0276] Comparative Example 1 is the same as Example 1 except that the Ce content is changed to 0%.

[0277] (Comparative Example 2)

[0278] Comparative Example 2 is the same as Example 8 except that the Ce content is changed to 0%.

[0279] (Comparative Example 3)

[0280] Comparative Example 3 is the same as Example 1 except that the length of the honeycomb filter is changed to 140 mm, the thickness of the partition is changed to 0.2 mm, and the porosity is changed to 50%.

[0281] [Table 1]

[0282]

[0283] [Table 2]

[0284]

[0285] Examples 1-16 are as follows: the opening ratio of the second honeycomb substrate is 75% or more, the porosity of the partition is 60% or more, and when assembled into an exhaust gas purification device, a catalyst is supported on the partition. The average flexural strength of the honeycomb filter at four points is 1.1 MPa or more in the state where the partition is not supported by a catalyst, or the average flexural strength of the honeycomb filter at four points is 1.5 MPa or more in the state where the partition is supported by a catalyst. In Examples 1-16, the retention performance is evaluated as "excellent" to "acceptable".

[0286] In contrast, Comparative Examples 1 and 2 are examples where the opening ratio of the second honeycomb substrate is 75% or more, the porosity of the partition is 60% or more, and a catalyst is supported on the partition when assembled into an exhaust gas purification device. However, the average flexural strength of the honeycomb filter at four points is less than 1.1 MPa when the partition is not supported by a catalyst, or less than 1.5 MPa when the partition is supported by a catalyst. In Comparative Examples 1 and 2, the retention performance was evaluated as "not possible".

[0287] Comparative Example 3 is an example where, when assembled into an exhaust gas purification device, a catalyst is supported in the partition wall, and the average flexural strength at four points of the honeycomb filter is 1.1 MPa or more in the state where the partition wall is not supported by a catalyst, or the average flexural strength at four points of the honeycomb filter is 1.5 MPa or more in the state where the partition wall is supported by a catalyst, but the opening ratio of the second honeycomb substrate is less than 75%, and the porosity of the partition wall is less than 60%. In Comparative Example 3, the evaluation of ensuring the battery space is "not possible".

[0288] Based on these results, it can be seen that the opening ratio of the second honeycomb substrate is 75% or more, the porosity of the partition is 60% or more, and when assembled into an exhaust gas purification device, the honeycomb filter with catalyst loaded in the partition has a four-point bending average strength of 1.1 MPa or more when the partition is not loaded with catalyst, or a four-point bending average strength of 1.5 MPa or more when the partition is loaded with catalyst. This can ensure the ash accumulation volume and reduce the heat capacity of the honeycomb filter, and can reduce the possibility of damage caused by the surface pressure of the gasket.

[0289] Furthermore, in Examples 1-16, Examples 1-3, 5-10, and 12-16 are examples where the average flexural strength at four points of the honeycomb filter is 1.2 MPa or more in the state where the partition wall is not loaded with catalyst, or 1.7 MPa or more in the state where the partition wall is loaded with catalyst. On the other hand, in Examples 1-16, Examples 4 and 11 are examples where the average flexural strength at four points of the honeycomb filter is less than 1.2 MPa in the state where the partition wall is not loaded with catalyst, or less than 1.7 MPa in the state where the partition wall is loaded with catalyst. In Examples 1-3, 5-10, and 12-16, the retention performance was evaluated as "excellent" or "good," but in Examples 4 and 11, the retention performance was evaluated as "acceptable." According to the results, it is more preferable that the average 4-point bending strength of the honeycomb filter is 1.2 MPa or more when the partition wall is not loaded with catalyst, or that the average 4-point bending strength of the honeycomb filter is 1.7 MPa or more when the partition wall is loaded with catalyst.

[0290] In particular, in Examples 1, 8, and 14-16, the average flexural strength at four points of the honeycomb filter in the state where the partition wall is not loaded with catalyst is 1.5 MPa or more, or the average flexural strength at four points of the honeycomb filter in the state where the partition wall is loaded with catalyst is 1.9 MPa or more, the retention performance was rated as "excellent". Based on this result, it is more preferable that the average flexural strength at four points of the honeycomb filter in the state where the partition wall is not loaded with catalyst is 1.5 MPa or more, or the average flexural strength at four points of the honeycomb filter in the state where the partition wall is loaded with catalyst is 1.9 MPa or more.

[0291] In Examples 17, 18, 27, 30, 32, and 33, the opening ratio of the second honeycomb substrate is 77% or more, and the porosity of the partition is 50% or more and 59% or less. When assembled into an exhaust gas purification device, the honeycomb filter with catalyst supported in the partition has a four-point bending average strength of 1.5 MPa or more when the partition is not supported by catalyst, or a four-point bending average strength of 1.8 MPa or more when the partition is supported by catalyst. In Examples 17, 18, 27, 30, 32, and 33, the retention performance is evaluated as "excellent" or "good".

[0292] According to the results, the opening ratio of the second honeycomb substrate is 77% or more, and the porosity of the partition is 50% or more and 59% or less. When assembled into an exhaust gas purification device, the honeycomb filter with catalyst loaded in the partition has a four-point bending average strength of 1.5 MPa or more when the partition is not loaded with catalyst, or a four-point bending average strength of 1.8 MPa or more when the partition is loaded with catalyst. This ensures the ash accumulation volume and reduces the heat capacity of the honeycomb filter, and also reduces the possibility of damage caused by the surface pressure of the gasket.

[0293] Examples 19-26, 28, 29, and 31 are as follows: the opening ratio of the second honeycomb substrate is 75% or more, the porosity of the partition is 50% or more and 59% or less, and when assembled into an exhaust gas purification device, the honeycomb filter without catalyst loading in the partition has a four-point bending average strength of 1.5 MPa or more. In Examples 19-26, 28, 29, and 31, the retention performance is evaluated as "excellent" or "good".

[0294] According to the results, the opening ratio of the second honeycomb substrate is 75% or more, and the porosity of the partition is 50% or more and 59% or less. When assembled into an exhaust gas purification device, the average bending strength of the honeycomb filter at four points is 1.5 MPa or more when the partition is not loaded with catalyst. This ensures the ash accumulation volume and reduces the heat capacity of the honeycomb filter, and also reduces the possibility of damage caused by the surface pressure of the gasket.

[0295] Examples 1-33 are wall-flow honeycomb filters assembled in an exhaust gas purification device, with or without catalyst supported in the partition walls. The main component of the partition walls is cordierite, and the opening ratio of the second honeycomb substrate is 75% or more. The average flexural strength at four points of the honeycomb filter assembled in the exhaust gas purification device is 1.5 MPa or more. The retention performance is rated as "Excellent" to "Acceptable".

[0296] According to the results, the honeycomb filter is a wall-flow type with or without catalyst in the partition wall when assembled in the exhaust gas purification device. The main component of the partition wall is cordierite, and the opening ratio of the second honeycomb substrate is more than 75%. When assembled in the exhaust gas purification device, the average bending strength of the honeycomb filter at four points is more than 1.5 MPa. Therefore, it can ensure the ash accumulation volume, reduce the heat capacity of the honeycomb filter, and reduce the possibility of damage caused by the surface pressure of the gasket.

[0297] In Examples 1-33 and Comparative Examples 1-33, the four-point flexural strength of the honeycomb filter assembled in the exhaust gas purification device was 1.5 MPa or higher, and the retention performance was rated as "acceptable" or higher. This result shows that by ensuring the four-point flexural strength of the honeycomb filter assembled in the exhaust gas purification device is 1.5 MPa or higher, the retention performance can be kept within an acceptable range.

[0298] In all the embodiments and comparative examples, the retention of the average isostatic strength of 1.2 MPa or more in Examples 1-3, 5-10, 12-33 and Comparative Example 3 was "good" or better. Therefore, from the viewpoint of ensuring retention, an isostatic strength of 1.2 MPa or more is more preferable.

[0299] In Examples 1-16 and Comparative Examples 1-3, Examples 5-10, 12-16 and Comparative Example 3, which contain 1 wt% or more of any one of cerium, zirconium and titanium, the retention is "good" or better. Therefore, from the viewpoint of retention, it is preferable to contain 1 wt% or more of any one of cerium, zirconium and titanium.

[0300] In Examples 1-16 and Comparative Examples 1-3, the average coefficient of thermal expansion at 40°C to 800°C was 1.2 ppm / K or higher, and in Comparative Example 3, the retention was rated as "good" or higher. Therefore, from the viewpoint of retention, an average coefficient of thermal expansion at 40°C to 800°C of 1.2 ppm / K or higher is preferred.

[0301] In Examples 1-16 and Comparative Examples 1-3, the retention performance was "excellent" in Examples 1, 8, and 14-16, where the partition wall had a glass layer comprising any one of cerium, zirconium, and titanium and the weight percentage of the glass layer exceeded 3%. Therefore, from the viewpoint of retention, it is preferable that the partition wall has a glass layer comprising any one of cerium, zirconium, and titanium and the weight percentage of the glass layer exceeds 3%.

Claims

1. A honeycomb filter, which is a wall-flow type honeycomb filter. The honeycomb filter has a honeycomb substrate and a sealing portion. The honeycomb substrate has a porous partition wall that divides into multiple cells extending from an inflow side end face to an outflow side end face. The sealing portion seals the cells on the inflow side end face or the outflow side end face. The cells of the honeycomb substrate include a first cell that opens on the inflow side end face and is sealed on the outflow side end face, and a second cell that opens on the outflow side end face and is sealed on the inflow side end face. In the exhaust gas purification system of a vehicle equipped with a gasoline engine, the honeycomb filter is positioned downstream of a flow-through honeycomb structure relative to the flow of exhaust gas. The main component of the partition wall is cordierite. The opening ratio of the honeycomb substrate is 75% or higher. The porosity of the partition wall is over 60%. When assembled into the exhaust gas purification device, a catalyst is supported on the partition wall. The average flexural strength of the honeycomb filter at four points is 1.1 MPa or more when the partition wall is not loaded with catalyst, or the average flexural strength of the honeycomb filter at four points is 1.5 MPa or more when the partition wall is loaded with catalyst.

2. The honeycomb filter according to claim 1, wherein, The average flexural strength of the honeycomb filter at four points is 1.2 MPa or more when the partition wall is not loaded with catalyst, or the average flexural strength of the honeycomb filter at four points is 1.7 MPa or more when the partition wall is loaded with catalyst.

3. A honeycomb filter, which is a wall-flow type honeycomb filter. The honeycomb filter has a honeycomb substrate and a sealing portion. The honeycomb substrate has a porous partition wall that divides into multiple cells extending from an inflow side end face to an outflow side end face. The sealing portion seals the cells on the inflow side end face or the outflow side end face. The cells of the honeycomb substrate include a first cell that opens on the inflow side end face and is sealed on the outflow side end face, and a second cell that opens on the outflow side end face and is sealed on the inflow side end face. In the exhaust gas purification system of a vehicle equipped with a gasoline engine, the honeycomb filter is positioned downstream of a flow-through honeycomb structure relative to the flow of exhaust gas. The main component of the partition wall is cordierite. The opening ratio of the honeycomb substrate is 77% or higher. The porosity of the partition wall is greater than 50% and less than 59%. When assembled into the exhaust gas purification device, a catalyst is supported on the partition wall. The average flexural strength of the honeycomb filter at four points is 1.5 MPa or more when the partition wall is not loaded with catalyst, or the average flexural strength of the honeycomb filter at four points is 1.8 MPa or more when the partition wall is loaded with catalyst.

4. A honeycomb filter, which is a wall-flow type honeycomb filter. The honeycomb filter has a honeycomb substrate and a sealing portion. The honeycomb substrate has a porous partition wall that divides into multiple cells extending from an inflow side end face to an outflow side end face. The sealing portion seals the cells on the inflow side end face or the outflow side end face. The cells of the honeycomb substrate include a first cell that opens on the inflow side end face and is sealed on the outflow side end face, and a second cell that opens on the outflow side end face and is sealed on the inflow side end face. In the exhaust gas purification system of a vehicle equipped with a gasoline engine, the honeycomb filter is positioned downstream of a flow-through honeycomb structure relative to the flow of exhaust gas. The main component of the partition wall is cordierite. The opening ratio of the honeycomb substrate is 75% or higher. The porosity of the partition wall is greater than 50% and less than 59%. When assembled into the exhaust gas purification device, no catalyst is supported on the partition wall. The average flexural strength of the honeycomb filter at four points when the partition wall is not loaded with catalyst is above 1.5 MPa.

5. A honeycomb filter, which is a wall-flow type honeycomb filter. The honeycomb filter has a honeycomb substrate and a sealing portion. The honeycomb substrate has a porous partition wall that divides into multiple cells extending from an inflow side end face to an outflow side end face. The sealing portion seals the cells on the inflow side end face or the outflow side end face. The cells of the honeycomb substrate include a first cell that opens on the inflow side end face and is sealed on the outflow side end face, and a second cell that opens on the outflow side end face and is sealed on the inflow side end face. In the exhaust gas purification system of a vehicle equipped with a gasoline engine, the honeycomb filter is positioned downstream of a flow-through honeycomb structure relative to the flow of exhaust gas to purify the exhaust gas. When assembled into the exhaust gas purification system, the filter may or may not contain a catalyst in the partition wall. The main component of the partition wall is cordierite. The opening ratio of the honeycomb substrate is 75% or higher. The average bending strength of the honeycomb filter at four points when assembled in the exhaust gas purification device is 1.5 MPa or more.

6. The honeycomb filter according to any one of claims 1 to 5, wherein the average isostatic pressure is 1.2 MPa or higher.

7. The honeycomb filter according to any one of claims 1 to 5, wherein, The partition wall contains more than 1 wt% of any one of cerium, zirconium, and titanium.

8. The honeycomb filter according to any one of claims 1 to 5, wherein, The average coefficient of thermal expansion in the direction of the pore extension at temperatures of 40°C to 800°C is above 1.2 ppm / K.

9. The honeycomb filter according to any one of claims 1 to 5, wherein, The partition has a glass layer comprising any one of cerium, zirconium, and titanium, wherein the weight percentage of the glass layer exceeds 3%.

10. The honeycomb filter according to any one of claims 1 to 5, used in a range-extended electric vehicle having a gasoline engine as a range extender for charging a battery.

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