Vehicle

Abstract

The utility model provides a kind of vehicle, it is equipped with the driving battery of being able to supply power to motor as the power source of vehicle, the internal combustion engine for charging driving battery, and the exhaust system for discharging exhaust gas from internal combustion engine to outside of vehicle, the exhaust system has: exhaust flow path, it extends from the outlet of internal combustion engine to exhaust port;First honeycomb structure of wall flow type with silencing function and exhaust purification function, it is set in the midway of exhaust flow path, carries or does not carry catalyst;And muffler, it is set in the midway of exhaust flow path and downstream side of first honeycomb structure of wall flow type, set the exhaust capacity of internal combustion engine as E (cm 3 ), set the total volume of muffler as M (cm 3 ), satisfy 0≤M / E≤1.5, and the noise from the position 0.5m of exhaust port center relative to the direction of exhaust flow towards upper 45° under predetermined condition when making internal combustion engine rated operation is 80dB or less.

Description

Technical Field

[0001] This utility model relates to vehicles. More specifically, this utility model relates to a vehicle comprising a drive battery capable of supplying electricity to a motor as a power source, an internal combustion engine for charging the drive battery, and an exhaust gas system for discharging exhaust gases emitted from the internal combustion engine to the outside of the vehicle. Background Technology

[0002] In recent years, there has been a societal need to curb CO2 emissions. Along with this, a shift is underway from vehicles powered solely by internal combustion engines to electric vehicles powered by electric motors. Among these electric vehicles are those that utilize an internal combustion engine to generate electricity for charging the drive battery, such as range extenders or series hybrid systems (e.g., range-extended EVs).

[0003] Even in electrified vehicles, the use of internal combustion engines emits harmful components such as HC, NOx, and CO, thus requiring purification. Therefore, in electrified vehicles that are supplemented by internal combustion engines, similar to conventional non-electrified vehicles that use only an internal combustion engine as the power source, a catalyst carrier carrying a three-way catalytic converter is used, and a filter is employed to remove particulate matter (PM) such as carbon particles generated through combustion. In addition, electrified vehicles equipped with internal combustion engines are also equipped with mufflers (silencers) to reduce exhaust noise from the internal combustion engine (Patent Documents 1 and 2).

[0004] Honeycomb structures with multiple pore channels are widely used as catalyst supports. There are also documents mentioning the possibility of miniaturizing mufflers by incorporating exhaust noise reduction functions within the honeycomb structure (Patent Document 3).

[0005] In addition, there is a known technology that, although it relates to an exhaust aftertreatment device for marine diesel internal combustion engines, reduces the required installation space by providing both a muffler chamber and an exhaust purification chamber within the hull (Patent Document 4).

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 2023-172814

[0009] Patent Document 2: Japanese Patent Application Publication No. 2021-116758

[0010] Patent Document 3: Japanese Patent Application Publication No. 2010-284599

[0011] Patent Document 4: International Publication No. 2015 / 180809 Utility Model Content

[0012] The problem to be solved by the utility model

[0013] Range-extended electric vehicles (REEVs) are electric vehicles equipped with internal combustion engines, consisting of a motor as the power source and an internal combustion engine for generating electricity. In addition to a large drive battery to ensure driving range, electric vehicles also require an inverter for motor control and a fuel tank for the internal combustion engine. This results in limited installation space and sacrifices in interior and cargo space.

[0014] Therefore, the objective of this invention is to reduce the space required for a device to suppress exhaust noise in a vehicle that includes a drive battery capable of supplying power to a motor that serves as the power source of the vehicle, an internal combustion engine for charging the drive battery, and an exhaust system for discharging exhaust gases emitted from the internal combustion engine to the outside of the vehicle.

[0015] Methods for solving problems

[0016] This invention addresses the aforementioned issues through in-depth research. It was discovered that the wall-flow honeycomb structure conventionally installed in exhaust systems, besides functioning as a filter, also possesses a noise reduction function. Furthermore, it was noted that in electric vehicles like range-extended electric vehicles (EVs) equipped with internal combustion engines, the internal combustion engine is not used as a power source; therefore, the exhaust volume can be smaller. Compared to conventional vehicles that use internal combustion engines as a power source, there is greater flexibility in miniaturizing the muffler. Consequently, it was found that, compared to the past, even by reducing the muffler volume and even eliminating the muffler altogether, the desired noise reduction effect can be achieved.

[0017] This utility model is based on this insight, as illustrated below.

[0018] [Method 1]

[0019] A vehicle includes: a drive battery capable of supplying electricity to a motor that serves as a power source for the vehicle; an internal combustion engine for generating electricity, used to charge the drive battery; and an exhaust gas system for discharging exhaust gases emitted from the internal combustion engine to the outside of the vehicle.

[0020] The exhaust gas system includes: an exhaust gas flow path extending from the outlet of the internal combustion engine to the exhaust port; a wall-flow type first honeycomb structure, which combines silencing and exhaust gas purification functions, disposed midway through the exhaust gas flow path and may or may not carry a catalyst; and a muffler disposed midway through the exhaust gas flow path and downstream of the wall-flow type first honeycomb structure.

[0021] The first honeycomb structure of the wall-flow type has: an outer peripheral sidewall; a plurality of inlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having an opening at the bottom surface of the inlet and a sealing portion at the bottom surface of the outlet; and a plurality of outlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having a sealing portion at the bottom surface of the inlet and an opening at the bottom surface of the outlet, and being adjacent to at least one of the plurality of inlet cells by a porous partition wall.

[0022] Let the displacement of the internal combustion engine be E (cm). 3 Let the total volume of the muffler be M (cm³). 3 When ), equation (1) is satisfied:

[0023] 0≤M / E≤1.5···Equation (1)

[0024] Furthermore, in a silencing chamber at 25°C and atmospheric pressure, during the charging of the drive battery by the internal combustion engine while the vehicle is stationary, the noise level at a position 0.5m away from the center of the exhaust port at a 45° angle relative to the direction of the exhaust flow when the internal combustion engine is running at its rated speed is below 80dB.

[0025] [Method 2]

[0026] A vehicle includes: a drive battery capable of supplying electricity to a motor that serves as a power source for the vehicle; an internal combustion engine for generating electricity, used to charge the drive battery; and an exhaust gas system for discharging exhaust gases emitted from the internal combustion engine to the outside of the vehicle.

[0027] The exhaust gas system includes: an exhaust gas flow path extending from the outlet of the internal combustion engine to the exhaust port; a wall-flow type first honeycomb structure, which combines silencing and exhaust gas purification functions, disposed midway through the exhaust gas flow path and may or may not carry a catalyst; and a muffler disposed midway through the exhaust gas flow path and downstream of the wall-flow type first honeycomb structure.

[0028] The first honeycomb structure of the wall-flow type has: an outer peripheral sidewall; a plurality of inlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having an opening at the bottom surface of the inlet and a sealing portion at the bottom surface of the outlet; and a plurality of outlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having a sealing portion at the bottom surface of the inlet and an opening at the bottom surface of the outlet, and being adjacent to at least one of the plurality of inlet cells by a porous partition wall.

[0029] Let the displacement of the internal combustion engine be E (cm). 3 Let the total volume of the first honeycomb structure of the wall flow type be H (cm³).3 Let the total volume of the muffler be M (cm³). 3 When ), equations (1) and (2) are satisfied:

[0030] 0≤M / E≤1.5···Equation (1)

[0031] 1.0≤(M+H) / E≤4.0···Equation (2)

[0032] Furthermore, when the sound of a 1kHz sound source loudspeaker located on the bottom side of the inlet is measured at 25°C and atmospheric pressure, the sound attenuation of the first honeycomb structure of the wall flow type is greater than 9dB.

[0033] [Method 3]

[0034] A vehicle includes: a drive battery capable of supplying electricity to a motor that serves as a power source for the vehicle; an internal combustion engine for generating electricity, used to charge the drive battery; and an exhaust gas system for discharging exhaust gases emitted from the internal combustion engine to the outside of the vehicle.

[0035] The exhaust gas system includes: an exhaust gas flow path extending from the outlet of the internal combustion engine to the exhaust port; and a wall-flow type first honeycomb structure, which combines silencing and exhaust gas purification functions, disposed midway through the exhaust gas flow path, and may or may not carry a catalyst. The exhaust gas system does not have a muffler.

[0036] The first honeycomb structure of the wall-flow type has: an outer peripheral sidewall; a plurality of inlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having an opening at the bottom surface of the inlet and a sealing portion at the bottom surface of the outlet; and a plurality of outlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having a sealing portion at the bottom surface of the inlet and an opening at the bottom surface of the outlet, and being adjacent to at least one of the plurality of inlet cells, sandwiched by a porous partition wall.

[0037] Let the displacement of the internal combustion engine be E (cm). 3 Let the total volume of the first honeycomb structure of the wall flow type be H (cm³). 3 When ), equation (3) is satisfied:

[0038] 0.8≤H / E≤2.0···Equation (3)

[0039] Furthermore, in a silencing chamber at 25°C and atmospheric pressure, during the charging of the drive battery by the internal combustion engine while the vehicle is stationary, the noise level at a position 0.5m away from the center of the exhaust port at a 45° angle relative to the direction of the exhaust flow when the internal combustion engine is running at its rated speed is below 80dB.

[0040] [Method 4]

[0041] A vehicle includes: a drive battery capable of supplying electricity to a motor that serves as a power source for the vehicle; an internal combustion engine for generating electricity, used to charge the drive battery; and an exhaust gas system for discharging exhaust gases emitted from the internal combustion engine to the outside of the vehicle.

[0042] The exhaust gas system includes: an exhaust gas flow path extending from the outlet of the internal combustion engine to the exhaust port; and a wall-flow type first honeycomb structure, which combines silencing and exhaust gas purification functions, disposed midway through the exhaust gas flow path, and may or may not carry a catalyst. The exhaust gas system does not have a muffler.

[0043] The first honeycomb structure of the wall-flow type has: an outer peripheral sidewall; a plurality of inlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having an opening at the bottom surface of the inlet and a sealing portion at the bottom surface of the outlet; and a plurality of outlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having a sealing portion at the bottom surface of the inlet and an opening at the bottom surface of the outlet, and being adjacent to at least one of the plurality of inlet cells by a porous partition wall.

[0044] Let the displacement of the internal combustion engine be E (cm). 3 Let the total volume of the first honeycomb structure of the wall flow type be H (cm³). 3 When ), equation (3) is satisfied:

[0045] 0.8≤H / E≤2.0···Equation (3)

[0046] Furthermore, when the sound of a 1kHz sound source loudspeaker located on the bottom side of the inlet is measured at 25°C and atmospheric pressure, the sound attenuation of the first honeycomb structure of the wall flow type is greater than 9dB.

[0047] [Method 5]

[0048] In any one of the methods 1 to 4, the exhaust system further has a flow-through type second honeycomb structure carrying a catalyst on the upstream side of the first honeycomb structure of the wall flow type.

[0049] [Method 6]

[0050] According to the vehicle of method 5, a three-way catalyst is respectively supported in the first honeycomb structure of the wall flow type and the second honeycomb structure of the flow type.

[0051] [Method 7]

[0052] The vehicle according to any one of methods 1 to 4, wherein the exhaust system does not have a flow-through second honeycomb structure.

[0053] [Method 8]

[0054] In the vehicle according to any one of methods 1 to 4, the first honeycomb structure of the wall flow type satisfies one or more of the following conditions (A) to (E).

[0055] (A) The surface of the partition is covered with a sound-absorbing layer.

[0056] Here, the average thickness of the sound-absorbing layer is more than 1% and less than 30% of the average thickness of the partition wall; the average pore size of the sound-absorbing layer is smaller than the average pore size of the partition wall, being more than 0.1 μm and less than 5 μm; the average porosity of the sound-absorbing layer is more than 35% and less than 90%; and the sound-absorbing layer is located in one or both of the plurality of inlet or outlet orifices.

[0057] (B) The opening area of ​​the opening is different between at least one of the plurality of inlet cells and at least one of the plurality of outlet cells adjacent to the inlet cell.

[0058] (C) The average thickness of the partition wall is 0.12 mm or more.

[0059] (D) A catalyst is supported inside the pores of the partition wall, and the amount of catalyst, calculated as alumina, is 20 g / L to 150 g / L relative to the volume of the first honeycomb structure of the wall flow type.

[0060] (E) At least one of the plurality of inlet cells is sandwiched between the porous material partition and adjacent to at least one of the plurality of inlet cells, and adjacent to at least one of the plurality of outlet cells.

[0061] [Method 9]

[0062] The vehicle according to any one of methods 1 to 4, wherein the first honeycomb structure of the wall flow pattern is made of ceramic.

[0063] Utility Model Effect

[0064] According to one embodiment of the present invention, in a vehicle comprising a drive battery capable of supplying electricity to a motor serving as a power source for the vehicle, an internal combustion engine for generating electricity to charge the drive battery, and an exhaust system for discharging exhaust gases emitted from the internal combustion engine to the outside of the vehicle, the space required for devices to suppress exhaust noise can be reduced. As a result, the exhaust system can be made more compact, thus allowing space to be allocated to improve vehicle convenience (such as increasing space for mounting the drive battery, or increasing interior space and cargo space). Attached Figure Description

[0065] Figure 1-1 This is a schematic diagram illustrating the configuration of the vehicle involved in the first embodiment of this utility model.

[0066] Figure 1-2 This is a schematic diagram illustrating the configuration of a vehicle according to a second embodiment of the present invention.

[0067] Figure 1-3 This is a schematic diagram illustrating a conventional vehicle configuration.

[0068] Figure 2-1 This is a schematic three-dimensional view of the first honeycomb structure representing the wall flow pattern.

[0069] Figure 2-2 This is a schematic cross-sectional view of the first honeycomb structure of the wall flow pattern when viewed from a section parallel to the direction of the lattice extension.

[0070] Figure 3 This is a schematic enlarged view of the partition wall of the first honeycomb structure when viewed from a section orthogonal to the direction of the lattice extension.

[0071] Figure 4-1 This is a schematic diagram illustrating an example of the configuration of a straight muffler.

[0072] Figure 4-2 This is a schematic diagram illustrating an example of the configuration of a multi-stage silencer.

[0073] Figure 5-1 It is a schematic three-dimensional diagram representing a flow-type second honeycomb structure.

[0074] Figure 5-2 This is a schematic cross-sectional view of the flow-type second honeycomb structure when viewed from a section parallel to the direction of the lattice extension.

[0075] Figure 6A This is the first example of a pore structure in which the inlet pore lattice is sandwiched by a porous partition and is adjacent to both the other inlet and outlet pore lattices.

[0076] Figure 6B This is the second example of a pore structure in which the inlet pore lattice is sandwiched by a porous partition and is adjacent to both the other inlet and outlet pore lattices.

[0077] Figure 6C This is the third example of a pore structure in which the inlet pore lattice is sandwiched by a porous partition and is adjacent to both the other inlet and outlet pore lattices.

[0078] Figure 7 This is a schematic diagram used to illustrate the structure of the exhaust gas system used in the simulation.

[0079] Figure 8 This is a schematic diagram illustrating a method for determining the sound-absorbing performance of a honeycomb structure.

[0080] Symbol Explanation

[0081] 10: Vehicle, 11: Motor, 12: Drive battery, 13: Internal combustion engine, 14: Exhaust system, 15: Drive wheel, 16: Inverter, 17: ECU, 100: First honeycomb structure, 101: First honeycomb structure, 102: Outer peripheral sidewall, 104: Inlet bottom surface, 106: Outlet bottom surface, 107: Opening, 108: Inlet aperture, 109: Sealing part, 110: Outlet aperture, 112: Partition wall, 113: Sound absorption layer, 122: Charging port, 131 132: Engine outlet; 133: Fuel inlet; 141: Exhaust gas flow path; 143: Exhaust port; 200: Second honeycomb structure; 202: Outer peripheral sidewall; 204: Inlet bottom surface; 206: Outlet bottom surface; 208: Perforated grid; 212: Partition wall; 301: Auxiliary muffler; 302: Main muffler; 310: Silencer chamber; 311: Inlet; 312: Outlet; 314: Shell; 316: Inner cylinder; 317: Perforation; 318: Sound-absorbing material; 319: Partition plate. Detailed Implementation

[0082] Next, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the present invention is not limited to the following embodiments, and design changes and improvements can be appropriately made based on the ordinary knowledge of those skilled in the art without departing from the spirit of the present invention.

[0083] <1. Vehicles>

[0084] Figure 1-1 The diagram shows the configuration of a vehicle according to one embodiment of the present invention. Figure 1-2 The diagram shows the configuration of a vehicle according to another embodiment of the present invention. Figure 1-3 The diagram shows a conventional vehicle configuration example. The vehicle 10 includes a drive battery 12 capable of supplying electricity to a motor 11, which serves as the power source for the vehicle 10; an internal combustion engine 13 for charging the drive battery 12; and an exhaust system 14 for discharging exhaust gases emitted from the internal combustion engine 13 to the outside of the vehicle.

[0085] (1-1. Drive System)

[0086] The driving battery 12 is a rechargeable battery capable of repeated charging and discharging, such as a lithium-ion battery, a nickel-metal hydride battery, or an all-solid-state battery. The capacity of the driving battery 12 is preferably 20 kWh or more, more preferably 30 kWh or more, for example, 20 to 100 kWh.

[0087] The internal combustion engine 13 can be composed of a known internal combustion engine such as a gasoline engine or a diesel engine. The vehicle 10 has a tank 133 for storing fuel supplied from the fuel inlet 132, and fuel is supplied to the internal combustion engine 13 from the tank 133. The vehicle according to this embodiment is equipped with an internal combustion engine 13 for generating electricity to charge the drive battery 12, but not with a drive engine. This helps to reduce the displacement of the internal combustion engine 13. The displacement of the internal combustion engine 13 is preferably 2500 cm³. 3 The following is more preferably 2000cm 3 The following is a further preferred size: 1500cm 3 The following, for example, are 300~2500cm 3 The displacement of the internal combustion engine 13 is derived from the product of the stroke volume and the number of cylinders.

[0088] The drive battery 12 can be charged externally and can store electricity supplied from the charging port 122. Additionally, the drive battery 12 can also power a generator (not shown) via the internal combustion engine 13, storing electricity generated by the generator. While electric vehicles like electric cars cannot drive when the drive battery 12's capacity is depleted, the presence of the generator-generating internal combustion engine 13 allows it to replenish power to the drive battery 12 when its capacity decreases. This extends the driving range beyond the capacity of the drive battery 12. A representative example of a vehicle equipped with a generator-generating internal combustion engine 13 is a range-extended electric vehicle (REEV).

[0089] Motor 11 is the power source of vehicle 10, outputting power to drive drive wheels 15. The maximum output of motor 11 can be set to 30kW or more, preferably 50kW or more, for example, 20-150kW. Motor 11 is electrically connected to drive battery 12 via inverter 16. Inverter 16 has the function of converting direct current (DC) to alternating current (AC), converting the DC power supplied from drive battery 12 into AC power to drive motor 11. Inverter 16 also has the function of controlling the frequency of AC power and adjusting the speed and torque of motor 11. Inverter 16 has multiple switching elements, and DC / AC conversion is performed by switching the switching elements on and off.

[0090] The ECU (Electronic Control Unit) 17 has a storage unit for storing various programs and other data, and a processing unit for performing various calculations, enabling it to control various devices in the vehicle. For example, the ECU 17 is connected to various devices such as the motor 11, the drive battery 12, and the internal combustion engine 13 via signal lines, and can perform control of these devices.

[0091] Specifically, as a controller of the internal combustion engine 13, the ECU 17 can control the fuel injection and ignition timing of the internal combustion engine 13. As a controller of the motor 11, the ECU 17 can perform switching control to turn the switching elements of the inverter 16 on and off.

[0092] In addition, ECU 17 can perform driving control of vehicle 10. By performing this driving control, vehicle 10 travels by using the power output of motor 11, which consumes the power of drive battery 12, while internal combustion engine 13 is stopped. As the power in motor 11 is consumed, the charging capacity of drive battery 12 decreases. Then, when the charging capacity decreases to a predetermined value, the stopped internal combustion engine 13 starts, generating electricity based on generator, and drive battery 12 is charged. When internal combustion engine 13 starts, if exhaust gas purification catalyst is provided in exhaust gas system 14, the catalyst temperature needs to be high in order to fully utilize the purification characteristics of the catalyst. Therefore, when ECU 17 anticipates the start of internal combustion engine 13, it can also perform preheating control to raise the temperature of exhaust gas purification catalyst.

[0093] (1-2. Exhaust Gas System)

[0094] The exhaust gas emitted from the internal combustion engine 13 is discharged to the outside of the vehicle through the exhaust gas system 14.

[0095] Reference Figure 1-3 In conventional vehicles, the exhaust system 14 includes: an exhaust flow path 141 extending from the outlet 131 of the internal combustion engine 13 to the exhaust port 143; a wall-flow type first honeycomb structure 101 with exhaust gas purification function, disposed midway through the exhaust flow path 141, carrying or not carrying a catalyst; a flow-through type second honeycomb structure 200 with exhaust gas purification function, disposed upstream of the wall-flow type first honeycomb structure 101; and a muffler 300 disposed midway through the exhaust flow path 141 and downstream of the wall-flow type first honeycomb structure 101. In conventional vehicles, the noise reduction function of the first honeycomb structure 101 is insufficient, therefore, to ensure the required noise reduction performance, the capacity of the muffler 300 needs to be increased. Therefore, in conventional vehicles, the muffler 300 includes a front auxiliary muffler and a rear main muffler.

[0096] Reference Figure 1-1In the first configuration example, the exhaust gas system 14 includes: an exhaust gas flow path 141 extending from the outlet 131 of the internal combustion engine 13 to the exhaust port 143; a wall-flow type first honeycomb structure 100, which combines silencing and exhaust gas purification functions, disposed midway through the exhaust gas flow path 141, carrying or not carrying a catalyst; a flow-type second honeycomb structure 200, which has exhaust gas purification functions, disposed midway through the exhaust gas flow path 141 and upstream of the wall-flow type first honeycomb structure 100; and a muffler 300, disposed midway through the exhaust gas flow path 141 and downstream of the wall-flow type first honeycomb structure 100. However, since the first honeycomb structure 100 has excellent silencing function, the capacity of the muffler 300 can be smaller than that of conventional vehicles. Therefore, in the vehicle of the first configuration example, the front auxiliary muffler is omitted as the muffler 300, and only the main muffler is provided. By omitting the secondary muffler, the space available for mounting the drive battery 12 can be increased.

[0097] Reference Figure 1-2 In the second configuration example, the exhaust gas system 14 includes: an exhaust gas flow path 141 extending from the outlet 131 of the internal combustion engine 13 to the exhaust port 143; a wall-flow type first honeycomb structure 100, which combines silencing and exhaust gas purification functions, disposed midway through the exhaust gas flow path 141, carrying or not carrying a catalyst; and a flow-type second honeycomb structure 200, which has exhaust gas purification functions, disposed midway through the exhaust gas flow path 141 and upstream of the wall-flow type first honeycomb structure 100. However, the exhaust gas system 14 does not have a muffler 300. That is, if the first honeycomb structure 100 has superior silencing function, the muffler 300 can be omitted. By omitting the muffler, the space for mounting the drive battery 12 can be significantly increased.

[0098] Reference Figure 2-1 as well as Figure 2-2 In both the first and second configuration examples, the first honeycomb structure 100 includes: an outer peripheral sidewall 102; a plurality of inlet cells 108 disposed on the inner peripheral side of the outer peripheral sidewall 102, extending from the inlet bottom surface 104 to the outlet bottom surface 106, having an opening at the inlet bottom surface 104 and a sealing portion 109 at the outlet bottom surface 106; and a plurality of outlet cells 110 disposed on the inner peripheral side of the outer peripheral sidewall 102, extending from the inlet bottom surface 104 to the outlet bottom surface 106, having a sealing portion 109 at the inlet bottom surface 104 and an opening at the outlet bottom surface 106, and being adjacent to at least one of the plurality of inlet cells 108 while sandwiched between porous partition walls 112. Typically, the plurality of inlet cells 108 and the plurality of outlet cells 110 extend in a straight line in a parallel manner.

[0099] For example, if exhaust gas containing particulate matter such as soot is supplied to the inlet bottom surface 104 on the upstream side of the first honeycomb structure 100, the exhaust gas is introduced into the inlet aperture 108 and flows downward within the inlet aperture 108. The outlet bottom surface 106 on the downstream side of the inlet aperture 108 is sealed, so the exhaust gas flows into the outlet aperture 110 through the porous partition 112 that divides the inlet aperture 108 and the outlet aperture 110. The particulate matter cannot pass through the partition 112, so it is captured and accumulates in the inlet aperture 108. After the particulate matter is removed, the clean exhaust gas flowing into the outlet aperture 110 flows downward within the outlet aperture 110 and exits from the outlet bottom surface 106 on the downstream side.

[0100] The exhaust gas encounters resistance as it passes through the porous partition wall 112. Furthermore, the exhaust gas contracts as it enters the vents of the partition wall 112 from the inlet vent 108 and expands as it flows out of the vents of the partition wall 112 to the outlet vent 110. This also contributes to noise reduction.

[0101] The noise reduction and exhaust gas purification performance of the first honeycomb structure 100 can vary according to the pore structure. This is achieved by using a method based on the displacement E (cm³) of the internal combustion engine 13 mounted on the vehicle 10. 3 The total volume M (cm³) of the muffler 300 and the silencer 300 3 The first honeycomb structure 100 with a suitable pore structure can achieve the required exhaust noise level and exhaust gas purification performance.

[0102] Therefore, the vehicle involved in the first embodiment can satisfy 0≤M / E≤1.5, preferably 0≤M / E≤1.4, more preferably 0≤M / E≤1.2, and even more preferably 0≤M / E≤1.1.

[0103] As for the muffler 300, the noise reduction performance of a typical main muffler is sufficient, and there is no need to add the noise reduction performance of a typical auxiliary muffler. Therefore, in the first configuration example equipped with the muffler 300, it is possible to satisfy 0.5≤M / E≤1.3, 0.8≤M / E≤1.2, 0.9≤M / E≤1.1, and 1.0≤M / E≤1.1.

[0104] The total volume M (cm³) of the muffler 300 mounted on vehicle 10 3 The preferred size is 2500cm. 3 The following is more preferably 2000cm 3 The following is a further preferred length of 800cm. 3 The following, for example, is 0~2500cm 3The volume of muffler 300 refers to the volume of water filling from the inlet to the outlet of the muffler chamber 310 when the muffler 300 is immersed in water and the chamber 310 of the muffler 300 is filled with water. The total volume of mufflers 300 refers to the sum of the volumes of all mufflers 300 mounted on the vehicle 10.

[0105] Even by miniaturizing the muffler 300 mounted on the vehicle 10, the noise level required by the vehicle 10 can be reduced to a practical level by employing a first honeycomb structure 100 with an appropriate pore structure. Specifically, in the anechoic chamber at 25°C and atmospheric pressure, while the vehicle is stationary and the drive battery 12 is being charged by the internal combustion engine 13, the noise level at a position 0.5m away from the center of the exhaust port 143 at a 45° angle relative to the direction of the exhaust flow when the internal combustion engine 13 is running at its rated speed can be below 80dB, for example, 75~79dB. When measuring the noise level, a noise meter of Class 1 suitable for JISC1509-1:2017 is used.

[0106] Running an internal combustion engine at its rated speed and torque means operating it at its rated speed and torque.

[0107] In this specification, the sound attenuation performance of the first honeycomb structure 100 is represented by the sound attenuation measured at 25°C and atmospheric pressure on the bottom side of the outlet when a 1kHz sound is generated from a sound source speaker located on the bottom side of the inlet. The measurement is performed in the following order: At 25°C and atmospheric pressure, a ceramic fiber gasket 440 with a thickness of 4mm is wound around the outer periphery of the first honeycomb structure 100, and the first honeycomb structure 100 is housed in a metal can 450 by compressing the gasket 440. Ferrite-based stainless steel can be used as the material for the metal can 450. Next, an inlet metal pipe 451 (20cm in length) is connected to the inlet side of the metal can 450, and an outlet metal pipe 452 (20cm in length) is connected to the outlet side. In a sealed state without sound leakage to the outside, a sound source speaker 410 is connected to the front end of the inlet metal pipe 451, and a microphone 420 of a noise meter is connected to the front end of the outlet metal pipe 452, thus constructing a sound attenuation performance measurement system 400. Figure 8 Next, the noise reduction performance measurement system 400 is suspended in an anechoic chamber at 25°C and atmospheric pressure using two metal wires 430 installed on the inlet metal pipe 451 and the outlet metal pipe 452. A noise meter is used on the bottom side of the outlet to measure the 1kHz sound generated by the sound source speaker 410 installed on the bottom side of the inlet, and the attenuation rate is calculated.

[0108] For the first honeycomb structure 100 used in the first embodiment, it is preferable that the sound attenuation is 9 dB or more, more preferably 10 dB or more, and even more preferably 12 dB or more. Higher sound attenuation is preferable, but if improved noise reduction performance is desired, the overall length and number of honeycomb structures can easily increase; furthermore, excessive noise reduction performance is not necessary. Therefore, the sound attenuation is preferably 40 dB or less, more preferably 30 dB or less, and even more preferably 25 dB or less. Thus, the sound attenuation is preferably, for example, 9 to 40 dB, more preferably 10 to 30 dB, and even more preferably 12 to 25 dB.

[0109] In addition, the sound attenuation was measured under the following conditions when the sound source loudspeaker generated from the 1kHz sound source on the bottom side of the inlet was measured at 25°C and atmospheric pressure on the bottom side of the outlet of the first honeycomb structure.

[0110] • Positional relationship between the sound source speaker and the bottom surface of the entrance of the first honeycomb structure: The sound source speaker is placed 20cm away from the center of gravity of the bottom surface of the entrance of the first honeycomb structure in a direction perpendicular to the bottom surface of the entrance.

[0111] • Initial sound pressure level produced by the loudspeaker: 100dB

[0112] • Positional relationship between the microphone and the bottom surface of the outlet of the first honeycomb structure: The microphone of the noise meter is set at a position 20cm away from the center of gravity of the bottom surface of the outlet of the first honeycomb structure in a direction perpendicular to the bottom surface of the outlet.

[0113] • Noise meter: Use a noise meter that conforms to Class 1 of JIS C1509-1:2017.

[0114] By using the first honeycomb structure 100 with the aforementioned noise reduction properties, it is possible to reduce the displacement E (cm³) relative to the internal combustion engine 13. 3 This reduces the total volume H (cm³) of the first honeycomb structure 100. 3 The total volume M (cm³) of the muffler 300 and the muffler 300 3 ) and.

[0115] Therefore, the vehicle according to one embodiment of this utility model satisfies equations (1) and (2):

[0116] 0≤M / E≤1.5···Equation (1)

[0117] 1.0≤(M+H) / E≤4.0···Equation (2)

[0118] The preferred embodiment of this utility model relates to a vehicle that satisfies equations (1) and (2):

[0119] 0≤M / E≤1.4···Equation (1)

[0120] 1.0≤(M+H) / E≤3.5···Equation (2)

[0121] A more preferred embodiment of this utility model relates to a vehicle that satisfies formulas (1) and (2):

[0122] 0≤M / E≤1.2···Equation (1)

[0123] 1.0≤(M+H) / E≤3.0···Equation (2)

[0124] In the first embodiment, the total volume H (cm³) of the first honeycomb structure 100 mounted on the vehicle 10 3 The preferred size is 2500cm. 3 The following is more preferably 2000cm 3 The following, for example, are 1000~2500cm 3 The volume of the first honeycomb structure 100 is a value determined based on the external dimensions of the first honeycomb structure 100 (e.g., height × bottom area). The total volume of the first honeycomb structure 100 refers to the sum of the volumes of all the first honeycomb structures 100 mounted on the vehicle 10.

[0125] In this way, even if the total volume of the first honeycomb structure 100 mounted on the vehicle 10 and the total volume of the muffler 300 are reduced, the required noise level of the vehicle 10 can be reduced to a practical level. Specifically, in the anechoic chamber at 25°C and atmospheric pressure, during the charging of the drive battery 12 by the internal combustion engine 13 when the vehicle is stationary, the noise level at a position 0.5m away from the center of the exhaust port 143 at a 45° angle relative to the direction of the exhaust flow when the internal combustion engine 13 is running at its rated speed can be below 80dB, for example, 75~79dB. When measuring the noise level, a noise meter of Class 1 suitable for JIS C1509-1:2017 is used.

[0126] As described above, the noise reduction performance and exhaust gas purification performance of the first honeycomb structure 100 can vary depending on the pore structure. Even when the muffler 300 is discharged from the exhaust system 14, the noise reduction performance can be adjusted according to the displacement E (cm³) of the internal combustion engine 13 mounted on the vehicle 10. 3 The first honeycomb structure 100 with a suitable lattice structure can also reduce the total volume H (cm²) of the first honeycomb structure 100. 3 At the same time, it achieves the required exhaust noise level and exhaust gas purification performance.

[0127] Therefore, the vehicle involved in the second configuration example can satisfy 0.8≤H / E≤2.0, preferably 1.0≤H / E≤2.0, more preferably 1.2≤H / E≤1.8, and even more preferably 1.2≤H / E≤1.5.

[0128] In the second configuration example, the total volume H (cm³) of the first honeycomb structure 100 mounted on the vehicle 10 3 The preferred size is 3500cm. 3 Below, 3000cm is preferred. 3 The following is a further preferred size: 2500cm 3 The following, for example, are 1000~3500cm 3 The volume of the first honeycomb structure 100 is a value determined based on the external dimensions of the first honeycomb structure 100 (e.g., height × bottom area). The total volume of the first honeycomb structure 100 refers to the sum of the volumes of all the first honeycomb structures 100 mounted on the vehicle 10.

[0129] Even excluding the muffler 300 mounted on the vehicle 10 and reducing the total volume of the first honeycomb structure 100, the noise level required by the vehicle 10 can be reduced to a practical level by employing the first honeycomb structure 100 with a suitable pore structure. Specifically, in a silencing chamber at 25°C and atmospheric pressure, while the vehicle is stationary and the drive battery 12 is being charged by the internal combustion engine 13, the noise level at a position 0.5m away from the center of the exhaust port 143 at a 45° angle relative to the direction of the exhaust flow when the internal combustion engine 13 is running at its rated speed can be below 80dB, for example, 75~79dB. When measuring the noise level, a noise meter of Class 1 suitable for JISC1509-1:2017 is used.

[0130] In the second embodiment, the sound attenuation of the first honeycomb structure 100 of the wall-flow type, measured at 25°C and atmospheric pressure on the bottom side of the outlet, from a 1kHz sound source loudspeaker located on the bottom side of the inlet, is preferably 9dB or more, more preferably 10dB or more, and even more preferably 12dB or more. Higher sound attenuation is preferred, but if improved noise reduction performance is desired, the overall length and number of honeycomb structures can easily increase; furthermore, excessive noise reduction performance is not necessary. Therefore, the sound attenuation is preferably 40dB or less, more preferably 30dB or less, and even more preferably 25dB or less. Thus, the sound attenuation is preferably, for example, 9 to 40dB, more preferably 10 to 30dB, and even more preferably 12 to 25dB. The order and conditions for measuring the attenuation of the 1kHz sound are as described above.

[0131] (1-3. First honeycomb structure)

[0132] As described above, the noise reduction performance of the first honeycomb structure 100 depends on the lattice structure. Several conditions exist for the lattice structure that are advantageous in improving the noise reduction performance of the first honeycomb structure 100; representative examples include (A) to (E) below. Therefore, in either the first configuration example or the second configuration example of the exhaust gas system 14, the first honeycomb structure 100 used preferably satisfies one or more of the conditions selected from (A) to (E), more preferably satisfies three or more of the conditions, and even more preferably satisfies four or more of the conditions.

[0133] <Condition(A)>

[0134] (A) The surface of partition 112 is covered by a sound-absorbing layer 113. The average thickness of the sound-absorbing layer 113 is more than 1% and less than 30% of the average thickness of partition 112. The average pore size of the sound-absorbing layer 113 is smaller than the average pore size of the partition, which is more than 0.1 μm and less than 5 μm. The average porosity of the sound-absorbing layer 113 is more than 35% and less than 90%. The sound-absorbing layer 113 is located in one or both of the multiple inlet grids 108 and the multiple outlet grids 110.

[0135] The average thickness of the sound-absorbing layer 113 is less than the average thickness of the partition wall 112, and the average pore size of the sound-absorbing layer 113 is less than the average pore size of the partition wall 112. If the surface of the partition wall 112 is covered by such a sound-absorbing layer 113, then the sound-absorbing layer 113 becomes a resistance to the passage of sound waves, and the sound waves are attenuated.

[0136] Condition (A) is preferably the following condition (A) + ).

[0137] (A + The surface of partition 112 is covered by a sound-absorbing layer 113. The average thickness of the sound-absorbing layer 113 is more than 5% and less than 30% of the average thickness of partition 112. The average pore size of the sound-absorbing layer 113 is more than 0.1 μm and less than 5 μm. The average porosity of the sound-absorbing layer 113 is more than 35% and less than 90%. The sound-absorbing layer 113 is located in one or both of the multiple inlet grids 108 and the multiple outlet grids 110.

[0138] Condition (A) is more preferably the following condition (A) ++ ).

[0139] (A ++ The surface of partition 112 is covered by a sound-absorbing layer 113. The average thickness of the sound-absorbing layer 113 is more than 5% and less than 25% of the average thickness of partition 112. The average pore size of the sound-absorbing layer 113 is more than 0.5μm and less than 4μm. The average porosity of the sound-absorbing layer 113 is more than 45% and less than 80%. The sound-absorbing layer 113 is located in one or both of the multiple inlet grids 108 and the multiple outlet grids 110.

[0140] Condition (A) is further preferably the following condition (A) +++ ).

[0141] (A +++ The surface of partition 112 is covered by a sound-absorbing layer 113. The average thickness of the sound-absorbing layer 113 is more than 10% and less than 25% of the average thickness of partition 112. The average pore size of the sound-absorbing layer 113 is more than 0.5 μm and less than 3 μm. The average porosity of the sound-absorbing layer 113 is more than 50% and less than 80%. The sound-absorbing layer 113 is located in one or both of the multiple inlet grids 108 and the multiple outlet grids 110.

[0142] The sound-absorbing layer 113 is preferably formed within at least one of the multiple inlet holes 108.

[0143] In one embodiment, the silencing layer 113 may be the same as a known collection layer sometimes provided on the partition wall 112 in a wall-flow honeycomb structure to improve the collection efficiency of particulate matter (PM). The collection layer improves the PM collection characteristics of soot and the like, thus facilitating the formation of a PM layer. This PM layer itself has a silencing effect. However, this is conditional on the following: the average thickness of the collection layer 113 is less than the average thickness of the partition wall 112, and the average pore size of the collection layer is less than the average pore size of the partition wall 112.

[0144] The trapping layer may contain one or more ceramics selected from cordierite, cerium oxide, mullite, zirconium phosphate, zircon, aluminum titanate, silicon carbide (SiC), silicon-silicon carbide composites (e.g., Si-bonded SiC), cordierite-silicon carbide composites, zirconium oxide, spinel, Indian quartz, pseudosapphire, corundum, titanium dioxide, and silicon nitride. From the viewpoint of preventing delamination due to differences in thermal expansion, the main component of the trapping layer is preferably the same type of ceramic as the partition wall. The main component of the trapping layer refers to a component comprising 50% by mass or more of the trapping layer. In the case where the partition wall 112 contains cordierite, the trapping layer preferably contains cordierite comprising 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more.

[0145] The cordierite content in the trapping layer was determined using the following method. For the trapping layer sample, one sample (3.0 g) was taken from two locations: one radially from the center of the honeycomb structure along its height and the other near the outer periphery. These samples were then pulverized to prepare the test samples. For each test sample, X-ray analysis was performed using Cu Kα-ray diffraction in the range of 2θ = 8° to 100°. The analysis was performed using the Rietveld analytical program RIETAN, which allowed the determination of the cordierite mass content.

[0146] In another embodiment, the silencing layer 113 may be the same as a known catalyst layer sometimes disposed on the partition wall 112 in a wall-flow honeycomb structure. However, the condition is that the average thickness of the catalyst layer serving as the silencing layer 113 is less than the average thickness of the partition wall 112, and the average pore size of the catalyst layer is less than the average pore size of the partition wall 112.

[0147] Examples of catalysts constituting the catalyst layer include PM combustion catalysts that assist in the combustion of PM such as soot, oxidation catalysts (DOC), SCR and NSR catalysts for removing nitrogen oxides (NOx), and three-way catalysts capable of simultaneously removing hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). From the viewpoint of meeting the purification requirements for NOx, CO, and HC, three-way catalysts are preferred. Catalysts may appropriately contain, for example, noble metals (Pt, Pd, Rh, etc.), alkali metals (Li, Na, K, Cs, etc.), alkaline earth metals (Mg, Ca, Ba, Sr, etc.), rare earth elements (Ce, Sm, Gd, Nd, Y, La, Pr, etc.), and transition metals (Mn, Fe, Co, Ni, Cu, Zn, Sc, Ti, Zr, V, Cr, etc.).

[0148] The silencing layer 113 may consist of only one of the trapping layer and the catalyst layer, or it may have a stacked structure in which the trapping layer and the catalyst layer are stacked in order of proximity to the partition wall.

[0149] The average thickness of the sound-absorbing layer 113 was measured according to the following steps. First, a sample of the partition 112 on which the sound-absorbing layer 113 is formed was selected from near the center in the height direction of the central axis A of the first honeycomb structure 100, and a section was cut out as shown in the figure. Figure 3 The cross-section shown is orthogonal to the direction of the extension of the perforated grid and observed using an optical microscope. In the microscopic photograph of this cross-section, the length T of the line segment N that crosses the sound-absorbing layer 113 when connecting the centroids O of adjacent perforated grids to each other at any 6 points is measured, and the average value is taken as the measured value.

[0150] The thickness of the partition wall 112 of the first honeycomb structure 100 refers to the length D of the line segment N that traverses the partition wall 112 when the centroids O of adjacent cells are connected by a line segment N in a cross section orthogonal to the direction of cell extension. Figure 3 The average thickness of partition 112 refers to the average thickness of all partitions. It should be noted that, in the presence of sound-absorbing layer 113, sound-absorbing layer 113 is excluded from the thickness of partition 112.

[0151] The average pore size of the sound-absorbing layer 113 was determined by image analysis of a microscope photograph of the same cross-section used when determining the average thickness of the sound-absorbing layer 113. Specifically, the sound-absorbing layer formed along the contours of any six pores from the microscope photograph was binarized for both voids and solids (Otsu's binarization), and the largest inscribed circle of each void was considered as the pore size for statistical processing to obtain the average value.

[0152] The porosity of the sound-absorbing layer 113 was determined by image analysis of a microscope photograph of the same cross section used when measuring the average thickness of the sound-absorbing layer 113. Specifically, the sound-absorbing layer formed along the contours of any six pores from the microscope photograph was binarized (Otsu's binarization), and the ratio of the voids to the total void and solid portions was calculated and used as the measured value.

[0153] <Condition (B)>

[0154] (B) The opening area of ​​the opening 107 is different between at least one of the plurality of inlet holes 108 and at least one, preferably all, of the plurality of outlet holes 110 adjacent to the inlet hole 108.

[0155] The opening area of ​​the opening 107 of the inlet orifice 108 is different from the opening area of ​​the opening 107 of the adjacent outlet orifice 110. As a result, when the exhaust gas moves from the inlet orifice 108 through the partition wall 112 to the outlet orifice 110, the exhaust gas expands and contracts, and the sound wave is attenuated.

[0156] Condition (B) is preferably the following condition (B) + ).

[0157] (B + More than 50% of the multiple inlet holes 108 have different opening areas relative to at least one, preferably all, of the multiple outlet holes 110 adjacent to each inlet hole 108.

[0158] Condition (B) is more preferably the following condition (B) ++ ).

[0159] (B ++ More than 80% of the multiple inlet holes 108 have different opening areas relative to at least one, preferably all, of the multiple outlet holes 110 adjacent to each inlet hole 108.

[0160] Condition (B) is further preferably the following condition (B) +++ ).

[0161] (B +++More than 90% of the inlet holes 108 have different opening areas relative to at least one, preferably all, of the multiple outlet holes 110 adjacent to each inlet hole 108.

[0162] <Condition(C)>

[0163] (C) The average thickness of the partition wall is 0.12 mm or more. By increasing the average thickness of the partition wall, the resistance to the passage of exhaust gas increases, and sound waves are more easily attenuated.

[0164] Condition (C) is preferably the following condition (C) + ).

[0165] (C + The average thickness of the partition is 0.15 mm or more.

[0166] Condition (C) is more preferably the following condition (C) ++ ).

[0167] (C ++ The average thickness of the partition is 0.16 mm or more.

[0168] Condition (C) is further preferably the following condition (C) +++ ).

[0169] (C +++ The average thickness of the partition is 0.17 mm or more.

[0170] There is no specific upper limit set for the average thickness of the partition wall. From the viewpoint of suppressing pressure loss during PM accumulation, the average thickness of the partition wall is preferably 0.24 mm or less, more preferably 0.22 mm or less, even more preferably 0.20 mm or less, and even more preferably 0.19 mm or less. Therefore, the average thickness of the partition wall is preferably, for example, 0.12 to 0.24 mm, more preferably 0.16 to 0.24 mm, even more preferably 0.17 to 0.22 mm, and even more preferably 0.18 to 0.20 mm.

[0171] The method for determining the average thickness of the partition wall is as described above.

[0172] <Condition (D)>

[0173] (D) A catalyst is supported inside the fine pores of the partition 112, and the amount of catalyst (alumina) is 20 g / L to 150 g / L relative to the volume of the first honeycomb structure of the wall flow type.

[0174] If the catalyst is supported inside the pores of partition 112, the resistance to the passage of exhaust gas will increase, and sound waves will be easily attenuated. The presence of a catalyst supported inside the pores of partition 112 can be verified by cross-sectional SEM-EDS (scanning electron microscopy with energy dispersive X-ray spectroscopy).

[0175] Here, catalyst amount refers to the amount of alumina that serves as a support for catalysts such as noble metals. Alumina itself is not a catalyst, but the amount of noble metals that act as catalysts is small and difficult to quantify. On the other hand, alumina accounts for a large proportion of the catalyst, so the amount of alumina is considered as catalyst amount. Catalyst amount (alumina amount) can be quantified as follows: 10g of the first honeycomb structure of the wall flow type carrying the catalyst (including the septa and catalyst layer) is collected unbiasedly from 6 sites of the first honeycomb structure of the wall flow type, pulverized, and the pulverized powder is made into particles and chemically analyzed according to fluorescence X-ray quantitative analysis.

[0176] Condition (D) is preferably the following condition (D) + ).

[0177] (D + The catalyst is carried inside the fine pores of the partition 112, and the amount of catalyst (alumina) is 20 g / L to 200 g / L relative to the volume of the first honeycomb structure of the wall flow type.

[0178] Condition (D) is more preferably the following condition (D) ++ ).

[0179] (D ++ The catalyst is carried inside the fine pores of the partition 112, and the amount of catalyst (alumina) is 30 g / L to 180 g / L relative to the volume of the first honeycomb structure of the wall flow type.

[0180] Condition (D) is further preferably the following condition (D) +++ ).

[0181] (D +++ The catalyst is carried inside the fine pores of the partition 112, and the amount of catalyst (alumina) is 50 g / L to 100 g / L relative to the volume of the first honeycomb structure of the wall flow type.

[0182] <Condition (E)>

[0183] (E) At least one of the plurality of inlet cells 108 is sandwiched with a porous partition wall 112 adjacent to at least one of the plurality of inlet cells 108 and adjacent to at least one of the plurality of outlet cells 110.

[0184] The inlet aperture 108 is adjacent to other inlet apertures 108 and also to the outlet aperture 110. As a result, when the exhaust gas moves from the inlet aperture 108 to the outlet aperture 110 through the partition wall, the distance the exhaust gas travels is easily increased, thereby attenuating the sound waves.

[0185] Condition (E) is preferably the following condition (E) + ).

[0186] (E + More than 50% of the inlet cells 108 are sandwiched by porous partitions 112 adjacent to at least one of the inlet cells 108 and adjacent to at least one of the outlet cells 110.

[0187] Condition (E) is more preferably the following condition (E) ++ ).

[0188] (E ++ More than 60% of the inlet cells 108 are sandwiched by porous partitions 112 adjacent to at least one of the inlet cells 108 and adjacent to at least one of the outlet cells 110.

[0189] Condition (E) is further preferably the following condition (E) +++ ).

[0190] (E +++ More than 80% of the inlet cells 108 are sandwiched by porous partitions 112 adjacent to at least one of the inlet cells 108 and adjacent to at least one of the outlet cells 110.

[0191] Figure 6A , Figure 6B and Figure 6C An example of a lattice structure that satisfies condition (E) is shown.

[0192] exist Figure 6A In this design, considering a single hexagonal outlet slot 110, six hexagonal inlet slots 108 surround the outlet slot 110, with each side adjacent to one of its sides. Furthermore, considering a single hexagonal inlet slot 108, each side of the inlet slot 108 is alternately adjacent to three outlet slots 110 and three inlet slots 108. The opening areas of an inlet slot 108 and an outlet slot 110 are designed to be the same. Figure 6A The perforated grid structure shown can extend the length of the adjacent partitions of the entrance perforations, thus improving the sound attenuation effect.

[0193] exist Figure 6BIn this design, considering a single exit aperture 110 with a quadrilateral cross-section, four hexagonal inlet apertures 108 surround the exit aperture 110 with each side adjacent to it. Furthermore, considering a single hexagonal inlet aperture 108, opposite pairs of sides of the inlet aperture 108 are adjacent to the exit aperture 110, and the remaining four sides are adjacent to the inlet aperture 108. The opening area of ​​an exit aperture 110 is designed to be larger than that of an inlet aperture 108. Figure 6B The illustrated lattice structure is advantageous in that it allows for free control of the ratio of the volume of the inlet lattice to the volume of the outlet lattice.

[0194] exist Figure 6C In this design, considering a single exit hole 110 with a quadrilateral cross-section, four octagonal entrance holes 108 surround the exit hole 110 with their sides adjacent to each other. Furthermore, considering an octagonal entrance hole 108, its sides are alternately adjacent to the four exit holes 110 and the four entrance holes 108. The cross-sectional area of ​​an exit hole 110 is smaller than that of an entrance hole 108. Figure 6C The aperture structure shown has partitions in which the inlet apertures are connected to each other, and the ratio of the opening area of ​​the inlet aperture to the opening area of ​​the outlet aperture can also be changed, which is advantageous in terms of controlling pressure loss characteristics.

[0195] Furthermore, the following describes the characteristics of the preferred first honeycomb structure for improving performance.

[0196] The bottom shape of the first honeycomb structure 100 is not limited. For example, it can be a circular shape, an ellipse, a racetrack shape, an oblong shape, or other circular shapes, a polygonal shape, a triangle, a quadrilateral, or other irregular shapes. The bottom shape of the first honeycomb structure 100 shown in the figure is circular, and the whole structure is cylindrical.

[0197] There is no particular limitation on the height of the first honeycomb structure 100 (the length from the bottom surface of the inlet to the bottom surface of the outlet), which can be appropriately set according to the application and performance requirements. For example, the height of the first honeycomb structure 100 can be 70mm to 200mm. There is also no particular limitation on the relationship between the height of the first honeycomb structure 100 and the maximum radial dimension of each bottom surface (referring to the maximum length of the diameter passing through the centroid of each bottom surface of the first honeycomb structure 100). Therefore, the height of the first honeycomb structure 100 can be longer than the maximum radial dimension of each bottom surface, or it can be shorter than the maximum radial dimension of each bottom surface.

[0198] The materials used for the partitions 112, outer peripheral sidewalls 102, and sealing portions 109 constituting the first honeycomb structure 100 are not limited, and ceramics can be cited as examples. Examples of ceramics include cordierite, cerium oxide, mullite, zirconium phosphate, zircon, aluminum titanate, silicon carbide (SiC), silicon-silicon carbide composites (e.g., Si-bonded SiC), cordierite-silicon carbide composites, zirconium oxide, spinel, Indian quartz, pseudosapphire, corundum, titanium dioxide, and silicon nitride. Furthermore, these ceramics may contain only one type or two or more types simultaneously.

[0199] From the perspectives of substrate strength, pressure loss, and exhaust gas purification performance, the cell density (number of cells per unit cross-sectional area) of the first honeycomb structure 100 is preferably 15 to 80 cells / cm². 2 More preferably, it is 46~60 pores / cm 2 Here, the cell density is calculated by dividing the total number of cells (including sealed cells) by the bottom area of ​​one side of the first honeycomb structure 100, excluding the outer peripheral sidewall 102.

[0200] From the viewpoint of suppressing the increase in pressure loss, the lower limit of the average porosity of the partitions 112 of the first honeycomb structure 100 is preferably 40% or more, more preferably 45% or more. Furthermore, from the viewpoint of the substrate strength of the first honeycomb structure 100, the upper limit of the average porosity of the partitions is preferably 70% or less, more preferably 65% ​​or less. Therefore, the average porosity of the partitions 112 is preferably, for example, 40% to 70%, more preferably 45% to 65%. In this specification, the porosity of the partitions 112 is determined by the mercury infiltration method specified in JISR 1655:2003. Furthermore, the average porosity of the partitions 112 is measured by taking samples (0.3 g each) of the partitions 112 from six locations of the first honeycomb structure 100 without bias and calculating the average porosity of each sample as the measured value.

[0201] In view of the improved PM capture efficiency and the balance of pressure loss, the average pore size of the partition wall 112 of the first honeycomb structure 100 is preferably 5~20μm, more preferably 6~15μm, and even more preferably 7~12μm.

[0202] In this specification, the average pore size of the partitions 112 of the first honeycomb structure 100 is determined using a mercury porosimeter and the mercury infiltration method specified in JIS R 1655:2003. The average pore size is the pore size at which 50% of the total pore volume of mercury is infiltrated from the micropore side. Samples (0.3 g) of six partitions 112 are collected unbiasedly from the first honeycomb structure 100, and their respective average pore sizes are measured. The average value is taken as the measured value.

[0203] The opening shape of the perforations (entrance and exit perforations) is not particularly limited. In a cross-section orthogonal to the direction of the perforation's extension, it can be a polygon (quadrilateral (rectangle, square), pentagon, hexagon, heptagon, octagon, etc.), a circle (circle, ellipse, oval, egg-shaped, oblong, etc.), etc. These shapes can be single or a combination of two or more. When the opening shape of the perforation is polygonal, the corners can be chamfered. It should be noted that... Figure 2-1 In the middle, the opening shape of the lattice is square.

[0204] (1-4. Muffler)

[0205] The muffler 300 is a noise reduction device that removes exhaust noise from the internal combustion engine 13. The noise reduction methods of the muffler 300 are represented by sound-absorbing and reactive types. The muffler 300 can be constructed using one or both of these noise reduction methods. Sound-absorbing methods use sound-absorbing materials such as glass fiber. Reactive methods utilize expansion, interference, resistance, and resonance to attenuate exhaust noise. Examples of reactive mufflers include multi-stage mufflers, counter-flow mufflers, expansion mufflers, and mufflers with Helmholtz resonators; two or more of these can be combined to form a muffler.

[0206] Midway through the exhaust gas flow path 141, a single muffler 300 or two or more may be installed. In conventional vehicles, a secondary muffler 301 and a main muffler 302 are connected in series as the muffler 300. The main muffler 302 has a larger volume than the secondary muffler 301.

[0207] Figure 4-1 and Figure 4-2 A specific structural example of the muffler 300 is shown. The muffler 300 shown in the figure has a silencing chamber 310 with a silencing function. The silencing chamber 310 is provided with an inlet 311 and an outlet 312, which are respectively connected to an exhaust gas flow path 141 made of a metal exhaust pipe or the like. The exhaust gas flowing into the silencing chamber 310 from the upstream exhaust gas flow path 141 through the inlet 311 is discharged from the outlet 312 to the downstream exhaust gas flow path 141 after the noise level is reduced in the silencing chamber 310.

[0208] The silencing chamber 310 may have a housing 314 and one or more inner cylinders 316 disposed within the housing 314 and having a plurality of perforations 317. In this case, exhaust gas flowing in the inner cylinder 316 is configured to flow out of the inner cylinder 316 through the plurality of perforations 317, and expansion-type silencing is performed at this time.

[0209] A representative example of a muffler 300 with an inner cylinder of 316 is... Figure 4-1The muffler shown is a straight type. The straight muffler has an inner cylinder 316 that runs from the inlet 311 to the outlet 312, penetrating the interior space of the silencing chamber 310. Multiple perforations 317 are provided in the inner cylinder 316 for expansion-type silencing. Alternatively, sound-absorbing material 318 can be filled inside the housing 314 and outside the inner cylinder 316 to achieve sound-absorbing silencing.

[0210] The inner cylinder 316 is a representative example of a muffler 300 with two or more components. Figure 4-2 A multi-stage silencer as shown. In the multi-stage silencer, the internal space of the silencing chamber 310 is divided into multiple chambers by one or more partitions 319. Furthermore, the movement of exhaust gas between the chambers is achieved via multiple inner cylinders 316. In the multi-stage silencer, the multiple inner cylinders 316 may or may not have multiple perforations 317, but it is preferable to have multiple perforations 317 on at least a portion of the inner cylinders 316. The silencing chamber 310 may have one or more chambers provided with sound-absorbing material 318 and one or more chambers without sound-absorbing material 318. Expansion-type silencing occurs within the multi-stage silencing chamber 310 as exhaust gas moves to different chambers. Expansion-type silencing occurs as exhaust gas flows out of the inner cylinders 316 through the perforations 317. Sound-absorbing silencing occurs in the chambers filled with sound-absorbing material 318. Resonance-type silencing occurs in the chambers not filled with sound-absorbing material 318. To eliminate sounds of various frequencies, it is preferable that the multiple chambers have different sizes.

[0211] Furthermore, counter-flow mufflers have a structure that reverses the exhaust flow midway, causing the sound waves to be reflected back. Noise reduction is achieved through the cancellation effect produced by the phase difference of the sound waves. Mufflers with Helmholtz resonators are effective at eliminating sound waves of specific frequencies.

[0212] In this specification, the noise reduction performance of the silencer is represented by the sound attenuation measured at the outlet side of the anechoic chamber at 25°C and atmospheric pressure, when a 1kHz sound source loudspeaker is installed at the inlet side of the anechoic chamber. The measurement is performed in the following order: At 25°C and atmospheric pressure, an inlet metal pipe (20cm long) is connected to the inlet side of the anechoic chamber, and an outlet metal pipe (20cm long) is connected to the outlet side. In a sealed state with no external sound leakage, a loudspeaker is connected to the front end of the inlet metal pipe, and a microphone of a noise meter is connected to the front end of the outlet metal pipe, thus constructing a noise reduction performance measurement system. Next, the noise reduction performance measurement system is suspended in the anechoic chamber at 25°C and atmospheric pressure using two metal wires installed on the inlet and outlet metal pipes. At the outlet side, a noise meter is used to measure the 1kHz sound source loudspeaker installed at the inlet side, and the attenuation rate is calculated.

[0213] When the silencer is used at 25°C and atmospheric pressure, the sound attenuation of a 1kHz sound source loudspeaker located at the entrance side of the anechoic chamber, measured at the outlet side, is preferably 10dB or more, more preferably 12dB or more, and even more preferably 15dB or more. Higher sound attenuation is preferred, but if higher silencing performance is desired, the overall length and number of silencers can easily increase; furthermore, excessive silencing performance is not necessary. Therefore, the sound attenuation is preferably 40dB or less, more preferably 30dB or less, and even more preferably 25dB or less. Thus, the sound attenuation is preferably, for example, 10-40dB, more preferably 12-30dB, and even more preferably 15-25dB.

[0214] In this specification, the sound attenuation when measuring a 1kHz sound generated from a loudspeaker located at the entrance side of the anechoic chamber at 25°C and atmospheric pressure is determined under the following conditions.

[0215] • The positional relationship between the sound source loudspeaker and the entrance of the silencer's anechoic chamber: The sound source loudspeaker is placed 20cm away from the center of the entrance opening of the silencer's anechoic chamber in a direction perpendicular to the entrance opening.

[0216] • Initial sound pressure level produced by the loudspeaker: 100dB

[0217] • The positional relationship between the microphone and the outlet of the silencer's silencing chamber: The microphone of the noise meter is placed 20cm away from the center of the opening of the silencer's silencing chamber outlet in a direction perpendicular to the opening of the outlet.

[0218] • Noise meter: Use a noise meter that conforms to Class 1 of JIS C1509-1:2017.

[0219] (1-5. Second honeycomb structure)

[0220] In both the first configuration example where the exhaust system 14 has a muffler 300 and the second configuration example where the exhaust system 14 does not have a muffler 300, the exhaust system 14 may also have a flow-through type second honeycomb structure 200 carrying a catalyst on the upstream side of the wall flow type first honeycomb structure 100.

[0221] Figure 5-1 as well as Figure 5-2Schematic perspective and cross-sectional views of a flow-through type second honeycomb structure 200 are shown respectively. The second honeycomb structure 200 includes: an outer peripheral sidewall 202; and porous partition walls 212 disposed on the inner peripheral side of the outer peripheral sidewall 202, dividing a plurality of cells 208 to form a flow path for fluid from the inlet bottom surface 204 to the outlet bottom surface 206. In the second honeycomb structure 200, each cell 208 is open at both ends. Exhaust gas flowing into a cell 208 from the inlet bottom surface 204 is purified during its passage through that cell 208 and flows out from the outlet bottom surface 206. Typically, the plurality of cells 208 extend in a straight line in a parallel manner.

[0222] The bottom shape of the second honeycomb structure 200 is not limited. For example, it can be a circular shape, an ellipse, a racetrack shape, an oblong shape, or other polygonal shapes such as triangles and quadrilaterals, as well as other irregular shapes. The honeycomb structure shown in the figure has a circular bottom shape and is cylindrical overall.

[0223] There are no particular restrictions on the height of the second honeycomb structure 200 (the length from the bottom surface of the inlet to the bottom surface of the outlet), which can be appropriately set according to the application and performance requirements. For example, the height of the second honeycomb structure 200 can be 50mm to 160mm. There are also no particular restrictions on the relationship between the height of the second honeycomb structure 200 and the maximum radial dimension of each bottom surface (referring to the maximum length of the diameter passing through the centroid of each bottom surface of the second honeycomb structure 200). Therefore, the height of the second honeycomb structure 200 can be longer than the maximum radial dimension of each bottom surface, or it can be shorter than the maximum radial dimension of each bottom surface.

[0224] The materials used for the partitions 212 and the outer peripheral sidewalls 202 constituting the second honeycomb structure 200 are not limited, and ceramics can be cited as examples. Examples of ceramics include cordierite, cerium oxide, mullite, zirconium phosphate, zircon, aluminum titanate, silicon carbide (SiC), silicon-silicon carbide composites (e.g., Si-bonded SiC), cordierite-silicon carbide composites, zirconium oxide, spinel, Indian quartz, pseudosapphire, corundum, titanium dioxide, and silicon nitride. Furthermore, these ceramics can contain only one type or two or more types simultaneously.

[0225] From the perspectives of substrate strength, pressure loss, and exhaust gas purification performance, the cell density (number of cells per unit cross-sectional area) of the second honeycomb structure 200 is preferably 47~190 cells / cm². 2 More preferably, it is 62~140 pores / cm 2 Here, the cell density is calculated by dividing the total number of cells (including sealed cells) by the bottom area of ​​one side of the second honeycomb structure 200, excluding the outer peripheral sidewall 202.

[0226] For the partition wall 212 of the second honeycomb structure 200, from the viewpoint of catalyst coating properties and to reduce heat capacity for better temperature rise, the lower limit of the average porosity measured by mercury infiltration is preferably 20% or more, more preferably 35% or more. Furthermore, from the viewpoint of the substrate strength of the second honeycomb structure, the upper limit of the average porosity of the partition wall 212 measured by mercury infiltration is preferably 65% ​​or less, more preferably 56% or less. Therefore, the average porosity of the partition wall 212 measured by mercury infiltration is preferably, for example, 20-65%, more preferably 35-56%. The method for measuring the average porosity of the partition wall 212 of the second honeycomb structure 200 is the same as the method for measuring the average porosity of the partition wall 112 of the first honeycomb structure 100.

[0227] From the viewpoint of catalyst coatability, the average pore size of the partition wall 212 of the second honeycomb structure 200 is preferably 0.5~6μm, more preferably 1~5μm, and even more preferably 2~5μm. The method for measuring the average pore size of the partition wall 212 of the second honeycomb structure 200 is the same as the method for measuring the average pore size of the partition wall 112 of the first honeycomb structure 100.

[0228] The opening shape of the lattice 208 in the second honeycomb structure 200 is not particularly limited. In a cross-section orthogonal to the direction of the lattice extension, it can be a polygon (quadrilateral (rectangle, square), pentagon, hexagon, heptagon, octagon, etc.), a circle (circle, ellipse, oval, egg-shaped, oblong, etc.), etc. These shapes can be single or a combination of two or more. When the opening shape of the lattice is polygonal, the corners can be chamfered. It should be noted that... Figure 5-1 In the diagram, the opening shape of the perforated grid is square.

[0229] From the viewpoint of ensuring strength, the average thickness of the partitions 212 in the second honeycomb structure 200 is preferably 38 μm or more, more preferably 45 μm or more, and even more preferably 50 μm or more. Furthermore, from the viewpoint of suppressing pressure loss, the average thickness of the partitions 212 is preferably 150 μm or less, more preferably 120 μm or less, and even more preferably 100 μm or less. Therefore, the average thickness of the partitions 212 is preferably, for example, 38 to 150 μm, more preferably 50 to 120 μm, and even more preferably 50 to 100 μm. The thickness of the partition refers to the length D of the line segment N that traverses the partition when the centroids O of adjacent cells are connected to each other by a line segment N in a cross section orthogonal to the direction of cell extension. The average thickness of the partition refers to the average of the thicknesses of all partitions. It should be noted that when a catalyst layer is provided on the surface of the partition, the thickness of the catalyst layer is not included in the thickness of the partition.

[0230] For the second honeycomb structure 200, a catalyst layer can be formed by coating the surface of the partition 212 with a catalyst corresponding to the purpose. Examples of catalysts constituting the catalyst layer include oxidation catalysts (DOC), SCR catalysts and NSR catalysts for removing nitrogen oxides (NOx), and three-way catalysts capable of simultaneously removing hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). From the viewpoint of the necessity for exhaust purification of gasoline engines widely used in PHV vehicles, three-way catalysts are preferred. The catalyst may appropriately contain, for example, noble metals (Pt, Pd, Rh, etc.), alkali metals (Li, Na, K, Cs, etc.), alkaline earth metals (Mg, Ca, Ba, Sr, etc.), rare earth elements (Ce, Sm, Gd, Nd, Y, La, Pr, etc.), transition metals (Mn, Fe, Co, Ni, Cu, Zn, Sc, Ti, Zr, V, Cr, etc.).

[0231] The second honeycomb structure 200 typically has low noise reduction performance. At 25°C and atmospheric pressure, when measuring a 1kHz sound generated by a loudspeaker located on the bottom side of the inlet, the sound attenuation is, for example, 0~2dB, typically 0.5~1.5dB. The order and conditions for measuring the 1kHz sound attenuation are as described above.

[0232] It should be noted that in both the first and second configuration examples, the exhaust gas system 14 may not have a flow-through second honeycomb structure 200. For example, by increasing the size of the first honeycomb structure, sufficient three-way catalyst can be loaded to adequately process CO and NO. X In the case of HC purification, the second honeycomb structure 200 is not required.

[0233] <2. Manufacturing Method of Cellular Structures>

[0234] The following describes, illustratively, methods for manufacturing a first and a second honeycomb structure. First, a raw material composition containing ceramic raw materials, a dispersion medium, a pore-forming material, and a binder is mixed to form a blank. The blank is then extruded to form a desired honeycomb structure. Additives such as dispersants may be added to the raw material composition as needed. During extrusion molding, a mold with desired overall shape, pore shape, partition wall thickness, pore density, etc., can be used.

[0235] In the case of a first honeycomb structure, after drying the honeycomb molded body, sealing portions are formed at predetermined positions on both bottom surfaces of the honeycomb molded body, and then the sealing portions are dried to obtain a honeycomb molded body with sealing portions. Next, the honeycomb molded body with sealing portions is degreased and fired to obtain the first honeycomb structure. Then, a sound-absorbing layer (such as a trapping layer or a catalyst layer) can be formed on the surface of the partition walls inside the cells of the first honeycomb structure.

[0236] In the case of obtaining a second honeycomb structure, after drying the honeycomb molded body, degreasing and firing are performed without forming sealing pores, thereby obtaining the second honeycomb structure. Then, a catalyst layer can be formed on the surface of the partition wall inside the pores of the second honeycomb structure.

[0237] As ceramic raw materials, materials capable of forming the aforementioned ceramics after firing can be used. Ceramic raw materials can be provided, for example, in powder form. Examples of ceramic raw materials include those used to obtain ceramics such as cordierite, cerium oxide, mullite, zircon phosphate, zircon, aluminum titanate, silicon carbide (SiC), silicon-silicon carbide composites (e.g., Si-bonded SiC), cordierite-silicon carbide composites, zirconium oxide, spinel, Indian stone, pseudosapphire, corundum, titanium dioxide, and silicon nitride. Specifically, examples include silicon dioxide, talc, alumina, kaolin, serpentine, pyrophyllite, brucite, boehmite, mullite, magnesite, and aluminum hydroxide, but there are no limitations. One type of ceramic raw material can be used alone, or two or more can be used in combination.

[0238] Cordierite is preferably used as the ceramic material for the partitions and outer peripheral walls of the first and second honeycomb structures. In this case, cordierite-modified raw materials can be used as ceramic raw materials. Cordierite-modified raw materials refer to raw materials that become cordierite through firing. The cordierite-modified raw materials preferably have a chemical composition of 30-45% by mass of alumina (Al2O3) (including the amount of aluminum hydroxide converted into alumina), 11-17% by mass of magnesium oxide (MgO), and 42-57% by mass of silicon dioxide (SiO2). The partitions (and outer peripheral walls) preferably contain cordierite of 50% by mass or more, more preferably 70% by mass or more, and even more preferably 90% by mass or more.

[0239] The cordierite content in the septum (outer peripheral sidewall) was determined by the following method. For the septum (outer peripheral sidewall) sample, one sample (3.0 g) was taken from two locations: one radially from the center of the honeycomb structure along its height and the other near the outer periphery. These samples were then pulverized to prepare the test samples. For each test sample, X-ray analysis was performed using Cu Kα-ray diffraction in the range of 2θ = 8–100°. The analysis was performed using the Rietveld analytical program RIETAN, which allowed the determination of the cordierite mass content.

[0240] Examples of dispersion media include water, or mixtures of water and organic solvents such as alcohols, with water being particularly preferred.

[0241] As a pore-forming material, there are no particular limitations as long as it becomes porous after firing. Examples include wheat flour, starch, foaming resin, water-absorbing resin, porous silica, carbon (e.g., graphite), ceramic spheres, polyethylene, polystyrene, polypropylene, nylon, polyester, acrylic acid, phenol, etc. One type of pore-forming material can be used alone, or two or more can be used in combination. From the viewpoint of improving the porosity of the fired body, the content of the pore-forming material relative to 100 parts by mass of the ceramic raw material is preferably 0.5 parts by mass or more, more preferably 2 parts by mass or more, and even more preferably 3 parts by mass or more. From the viewpoint of ensuring the strength of the fired body, the content of the pore-forming material relative to 100 parts by mass of the ceramic raw material is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 4 parts by mass or less.

[0242] Examples of adhesives include organic adhesives such as methylcellulose, hydroxypropyl methylcellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and polyvinyl alcohol. The combination of methylcellulose and hydroxypropyl methylcellulose is particularly preferred. Furthermore, from the viewpoint of improving the strength of the honeycomb molded body, the adhesive content is preferably 4 parts by mass or more, more preferably 5 parts by mass or more, and even more preferably 6 parts by mass or more, relative to 100 parts by mass of the ceramic raw material. From the viewpoint of suppressing cracking caused by abnormal heating during the firing process, the adhesive content is preferably 9 parts by mass or less, more preferably 8 parts by mass or less, and even more preferably 7 parts by mass or less, relative to 100 parts by mass of the ceramic raw material. One type of adhesive can be used alone, or two or more types can be used in combination.

[0243] Dispersants can include ethylene glycol, dextrin, fatty acid soaps, polyether polyols, etc. A single dispersant can be used, or two or more can be used in combination. The preferred content of the dispersant relative to 100 parts by weight of the ceramic raw material is 0 to 2 parts by weight.

[0244] There is no particular limitation on the method for sealing the bottom surface of the honeycomb molded body; known methods such as scraping and pressing can be used. When forming the sealing portion, it is preferable to form the sealing portion on both bottom surfaces of the dried honeycomb molded body and then dry the sealing portion. There are no particular limitations on the material of the sealing portion; however, ceramic is preferred from the viewpoint of strength and heat resistance. As a ceramic, it is preferred to contain at least one ceramic material selected from cordierite, cerium oxide, mullite, zircon, aluminum titanate, silicon carbide (SiC), silicon-silicon carbide composites (e.g., Si-bonded SiC), cordierite-silicon carbide composites, zirconium oxide, spinel, Indian stone, pseudosapphire, corundum, titanium dioxide, and silicon nitride. To ensure uniform expansion during firing and improve durability, the sealing portion is more preferably composed of the same material as the main body of the honeycomb molded body.

[0245] After drying the honeycomb molded body, it undergoes degreasing and firing to manufacture a first honeycomb structure or a second honeycomb structure. The conditions for the drying, degreasing, and firing processes can be well-known conditions based on the material composition of the honeycomb molded body, and no special explanation is required. Examples of specific conditions are given below.

[0246] In the drying process, conventionally known drying methods such as hot air drying, microwave drying, dielectric drying, reduced pressure drying, vacuum drying, and freeze drying can be used. Among these, considering the ability to dry the molded body quickly and uniformly, a drying method combining hot air drying with microwave drying or dielectric drying is preferred.

[0247] Next, the degreasing process will be explained. The combustion temperature of the adhesive is around 200℃, and the combustion temperature of the pore-forming material is around 300~1000℃. Therefore, the degreasing process only requires heating the honeycomb molded body to a temperature range of around 200~1000℃. There is no particular limitation on the heating time, which is usually around 10~100 hours. The honeycomb molded body after the degreasing process is called the pre-fired body.

[0248] The firing process also depends on the material composition of the honeycomb molded body. For example, it can be carried out by heating the pre-fired body to 1350~1600℃ and holding it for 3~10 hours.

[0249] Methods for increasing the average fine pore size of the partition walls include using materials with large particle sizes or setting a higher firing temperature for further sintering. Conversely, methods for decreasing the average fine pore size of the partition walls include using materials with small particle sizes or lowering the firing temperature to suppress sintering. Methods for increasing the average porosity of the partition walls include adding pore-forming material components that disappear during firing. Conversely, methods for decreasing the average porosity of the partition walls include reducing the amount of organic binder contained in the honeycomb molded body.

[0250] The surface of the partition walls of the first honeycomb structure thus manufactured can also be covered with a sound-absorbing layer. In one embodiment, the sound-absorbing layer may be the same as a known trapping layer sometimes disposed on the partition walls in wall-flow honeycomb structures to improve the trapping efficiency of particulate matter (PM). In another embodiment, the sound-absorbing layer may be the same as a known catalyst layer sometimes disposed on the partition walls in wall-flow honeycomb structures. In yet another embodiment, the sound-absorbing layer may have a stacked structure in which a trapping layer and a catalyst layer are sequentially stacked.

[0251] An exemplary method for forming a trapping layer includes: spraying an aerosol containing ceramic particles toward the center of the bottom surface of the inlet side of a first honeycomb structure in a direction perpendicular to the bottom surface of the inlet side, while simultaneously applying an attractive force to the bottom surface of the outlet side, thereby attracting the sprayed aerosol from the bottom surface of the inlet side and causing the ceramic particles to adhere to the surface of the partition wall within the inlet pores; and a step of heat-treating the first honeycomb structure with the attached ceramic particles at a maximum temperature of 1000°C or higher for at least 1 hour, typically at a maximum temperature of 1100°C to 1400°C for 1 hour to 6 hours. Through heat treatment, the ceramic particles are sintered into the partition wall within the inlet pores, forming a trapping layer covering the surface of the partition wall of the inlet pores. The thickness of the trapping layer can be adjusted by the amount of ceramic particles attached. Specific examples of the method for forming the trapping layer are described in Japanese Patent Application Publication No. 2022-158915.

[0252] An exemplary method for forming a catalyst layer can be described as follows: A catalyst slurry is introduced into a pore structure using a known impregnation or suction method, allowing it to adhere to the surface and pores of the partition wall. Following this, a high-temperature treatment is performed to sinter the catalyst contained in the slurry and support it on the partition wall. The type of catalyst is as described above. The thickness of the catalyst layer can be adjusted by the viscosity of the catalyst slurry.

[0253] One method to increase the average pore size of the sound-absorbing layer is to control the particle size of the alumina particles used as aggregate in the sound-absorbing layer through a crushing process, resulting in a large particle size (e.g., 3 μm or larger). Alternatively, carbon or resin particles can be used as pore-forming materials to increase their particle size. Conversely, methods to decrease the average pore size include reducing the particle size of the aggregate in the sound-absorbing layer and reducing the particle size when using pore-forming materials.

[0254] Example

[0255] The following are examples of embodiments for better understanding of the present invention and its advantages, but the present invention is not limited to these embodiments.

[0256] <1. Manufacturing of the First Cellular Structure>

[0257] (1-1. Honeycomb Structure A)

[0258] To 100 parts by weight of cordierite petrochemical raw material, 5 parts by weight of pore-forming material, 60 parts by weight of dispersion medium, and 4 parts by weight of organic binder were added, and the mixture was stirred and kneaded to prepare clay. Alumina, aluminum hydroxide, kaolin, talc, and silica were used as the cordierite petrochemical raw material. Water was used as the dispersion medium. Methylcellulose was used as the organic binder. A water-absorbing resin with a median particle size of 20 μm was used as the pore-forming material. In this embodiment, the median particle size of the raw materials, etc., is the particle size (D50) at which the cumulative value in the particle size distribution is determined by laser diffraction scattering.

[0259] Next, the clay is extruded using a die that acts as a honeycomb molding mechanism to obtain a honeycomb molded body with an overall cylindrical shape.

[0260] Next, the honeycomb molded body is dried using a microwave dryer, and then further dried using a hot air dryer. Finally, the two ends of the honeycomb molded body are cut off and adjusted to the predetermined size.

[0261] Next, a slurry for forming the sealing portions is prepared using the same material as the honeycomb molded body. Then, using the slurry, sealing portions are formed at the openings of predetermined cells on the inlet bottom side and the openings of remaining cells on the outlet bottom side of the dried honeycomb molded body. Specifically, the inlet cells sealed on the outlet side and the outlet cells sealed on the inlet side are alternately adjacent and arranged in a regular pattern.

[0262] Next, the honeycomb molded body with each sealing section is degreased in an atmospheric atmosphere at approximately 200-1000°C, and then fired in an atmospheric atmosphere at approximately 1410-1440°C to produce a wall-flow honeycomb structure. The resulting honeycomb structure has a cordierite content of over 95% by mass in the partitions and outer peripheral sidewalls, and is cylindrical with a circular bottom surface at the inlet and outlet.

[0263] For the obtained cellular structures, the various properties shown below were measured. The results are presented in Table 1.

[0264] • Dimensions and volume

[0265] • The shape of the aperture opening (inlet aperture, outlet aperture) in a section perpendicular to the direction of aperture extension.

[0266] • The opening area of ​​the bottom surface of the inlet and outlet holes in the section perpendicular to the direction of hole extension (the total opening area of ​​the inlet and outlet holes).

[0267] •Puncture density

[0268] • Average thickness of the partition

[0269] • Average pore size of the partition wall

[0270] • Average porosity of the partition

[0271] Furthermore, utilizing the Japanese Patent Application Publication No. 2022-158915... Figure 8 The particle attachment device described herein sprays an aerosol containing a slurry of ceramic particles (material: cordierite, median particle size: 3μm) and silica sol (silica concentration 20% by mass, median particle size 80nm) in a mass ratio of cordierite:silica = 9:1 at a predetermined time towards the center of the bottom surface of the entrance side of the honeycomb structure, in a direction perpendicular to the bottom surface of the entrance side, so that the ceramic particles adhere to the surface of the partition wall inside the entrance pores.

[0272] Then, the ceramic particles attached to the bottom surface of the entrance of the honeycomb structure are removed by vacuum. The honeycomb structure is then placed in an electric furnace and heated in an atmospheric atmosphere at a maximum temperature of 800°C for 1 hour. This forms a trapping layer as a sound-absorbing layer on the surface of the partition wall inside the entrance pore.

[0273] For the sound-absorbing layer of the honeycomb structure filter obtained by the above manufacturing method, the average thickness, average pore size, and average porosity were measured using the same method. The results are shown in Table 1. It should be noted that the required number of honeycomb structures were fabricated for various performance evaluations.

[0274] (1-2. Cellular Structure A')

[0275] Apart from changing the size and volume, the wall flow type of the honeycomb structure is obtained by following the same steps as that of the honeycomb structure A.

[0276] (1-3. Honeycomb Structure B)

[0277] Using the same raw material composition as honeycomb structure A, the clay is extruded and shaped using a die with a honeycomb molding mechanism to obtain a honeycomb molded body with an overall cylindrical shape.

[0278] Next, the honeycomb molded body is dried using a microwave dryer, and then further dried using a hot air dryer. Finally, the two ends of the honeycomb molded body are cut off and adjusted to the predetermined size.

[0279] Next, a slurry for forming the sealing portions is prepared using the same material as the honeycomb molded body. Then, using the slurry, sealing portions are formed at the openings of predetermined cells on the inlet bottom side and the openings of remaining cells on the outlet bottom side of the dried honeycomb molded body.

[0280] Next, the honeycomb molded body with each sealing section is degreased in an atmospheric atmosphere at approximately 200-1000°C, and then fired in an atmospheric atmosphere at approximately 1410-1440°C to produce a wall-flow honeycomb structure. The resulting honeycomb structure has a cordierite content of over 95% by mass in the partitions and outer peripheral sidewalls, and is cylindrical with a circular bottom surface at the inlet and outlet.

[0281] For the obtained honeycomb structures, various properties were measured in the same manner as before. The results are shown in Table 1. The main difference between honeycomb structure B and honeycomb structure A lies in the lattice structure and the presence or absence of a sound-absorbing layer. The lattice structure of honeycomb structure B, besides the structure adjacent to the outer peripheral sidewalls, includes... Figure 6C The diagram shows a structure where the entrance cells are adjacent to each other. It should be noted that the required number of honeycomb structures were fabricated to implement various performance evaluations.

[0282] (1-4. Honeycomb structure B')

[0283] Apart from changing the size and volume, the wall flow type of the honeycomb structure is obtained by following the same steps as honeycomb structure B.

[0284] (1-5. Honeycomb Structure C)

[0285] Using the same raw material composition as honeycomb structure A, the clay is extruded and shaped using a die with a honeycomb molding mechanism to obtain a honeycomb molded body with an overall cylindrical shape.

[0286] Next, the honeycomb molded body is dried using a microwave dryer, and then further dried using a hot air dryer. Finally, the two ends of the honeycomb molded body are cut off and adjusted to the predetermined size.

[0287] Next, a slurry for forming the sealing portions is prepared using the same material as the honeycomb molded body. Then, using the slurry, sealing portions are formed at the openings of predetermined cells on the inlet bottom side and the openings of remaining cells on the outlet bottom side of the dried honeycomb molded body. Specifically, the inlet cells sealed on the outlet side and the outlet cells sealed on the inlet side are alternately adjacent and arranged in a regular pattern.

[0288] Next, the honeycomb molded body with each sealing section is degreased in an atmospheric atmosphere at approximately 200-1000°C, and then fired in an atmospheric atmosphere at approximately 1410-1440°C to produce a wall-flow honeycomb structure. The resulting honeycomb structure has a cordierite content of over 95% by mass in the partitions and outer peripheral sidewalls, and is cylindrical with a circular bottom surface at the inlet and outlet.

[0289] For the obtained cellular structures, various properties were measured in the same manner as before. The results are shown in Table 1. Cellular structure C differs from cellular structure A mainly in the average thickness of the partitions and the presence or absence of a sound-absorbing layer. It should be noted that the required number of cellular structures were fabricated for the various property evaluations.

[0290] (1-6. Honeycomb structure C')

[0291] Apart from changing the size and volume, the wall flow type of the honeycomb structure is obtained by following the same steps as the honeycomb structure C.

[0292] (1-7. Honeycomb Structure D)

[0293] Using the same raw material composition as honeycomb structure A, the clay was extruded and shaped using a die acting as a honeycomb molding mechanism to obtain a honeycomb molded body with an overall cylindrical shape. Then, under the same manufacturing conditions as honeycomb structure A, drying, sealing, degreasing, and firing were performed to obtain a wall-flow honeycomb structure. The obtained honeycomb structure had a cordierite content of 95% by mass in the septa and outer peripheral sidewalls, and was cylindrical with a circular inlet and outlet bottom surface. Various properties of the obtained honeycomb structure were measured as before. The results are shown in Table 1.

[0294] Next, a predetermined amount of catalyst slurry containing a ternary catalyst (Pt, Pd, Rh, alumina, cerium oxide) was introduced into the inlet cells of the honeycomb structure using a suction method. The catalyst in the slurry was sintered onto the partition walls under atmospheric conditions at 600°C for 1 hour, forming a catalyst layer as a sound-absorbing layer on the surface of the partition walls within the inlet cells. At this time, the slurry viscosity was adjusted by loading the catalyst into the fine pores of the partition walls. The catalyst amount relative to the volume of the honeycomb structure was 80 g / L. The method for determining the catalyst amount is as described above.

[0295] For the sound-absorbing layer of the honeycomb structure filter obtained by the above manufacturing method, the average thickness, average pore size, and average porosity were measured using the same method. The results are shown in Table 1. The main difference between honeycomb structure D and honeycomb structure A is that a catalyst layer is formed on the surface of the partition wall to replace the trapping layer as the sound-absorbing layer. In addition, the amount of catalyst layer is also greater. It should be noted that the required number of honeycomb structures for various performance evaluations were fabricated.

[0296] (1-8. Honeycomb structure D')

[0297] Apart from changing the size and volume, the wall flow type of the honeycomb structure is obtained by following the same steps as the honeycomb structure D.

[0298] (1-9. Honeycomb Structure E)

[0299] Using the same raw material composition as honeycomb structure A, the clay is extruded and shaped using a die with a honeycomb molding mechanism to obtain a honeycomb molded body with an overall cylindrical shape.

[0300] Next, the honeycomb molded body is dried using a microwave dryer, and then further dried using a hot air dryer. Finally, the two ends of the honeycomb molded body are cut off and adjusted to the predetermined size.

[0301] Next, a slurry for forming the sealing portions is prepared using the same material as the honeycomb molded body. Then, using the slurry, sealing portions are formed at the openings of predetermined cells on the inlet bottom side and the openings of remaining cells on the outlet bottom side of the dried honeycomb molded body.

[0302] Next, the honeycomb molded body with each sealing section is degreased in an atmospheric atmosphere at approximately 200-1000°C, and further fired in an atmospheric atmosphere at approximately 1410-1440°C to produce a wall-flow honeycomb structure. The resulting honeycomb structure has a cordierite content of 95% by mass or more in the partition walls and outer peripheral sidewalls, and is cylindrical with a circular bottom surface at the inlet and outlet.

[0303] For the obtained honeycomb structures, various properties were measured in the same manner as before. The results are shown in Table 1. The main difference between honeycomb structure E and honeycomb structure A is that, apart from the presence or absence of a sound-absorbing layer, the opening shape and opening area of ​​the inlet and outlet pores are different. The pore structure of honeycomb structure E, except for the structure adjacent to the outer peripheral sidewall, such as... Figure 6A The diagram shows a structure where the entrance cells are adjacent to each other. It should be noted that the required number of honeycomb structures were fabricated to implement various performance evaluations.

[0304] (1-10. Cellular Structure E')

[0305] Apart from changing the size and volume, the wall flow type of the honeycomb structure is obtained by following the same steps as the honeycomb structure E.

[0306] (1-11. Honeycomb Structure F)

[0307] Using the same raw material composition as honeycomb structure A, the clay is extruded and shaped using a mold that acts as a honeycomb molding mechanism to obtain a honeycomb molded body with an overall cylindrical shape.

[0308] Next, the honeycomb molded body is dried using a microwave dryer, and then further dried using a hot air dryer. Finally, the two ends of the honeycomb molded body are cut off and adjusted to the predetermined size.

[0309] Next, a slurry for forming the sealing portions is prepared using the same material as the honeycomb molded body. Then, using the slurry, sealing portions are formed at the openings of predetermined cells on the inlet bottom side and the openings of remaining cells on the outlet bottom side of the dried honeycomb molded body.

[0310] Next, the honeycomb molded body with each sealing section was degreased in an atmospheric atmosphere at approximately 200–1000°C, and then fired in an atmospheric atmosphere at approximately 1410–1440°C to produce a wall-flow honeycomb structure. The resulting honeycomb structure had a cordierite content of over 95% by mass in the septa and outer peripheral sidewalls, and was cylindrical with a circular inlet and outlet bottom surface. Various properties of the resulting honeycomb structure were measured as before. The results are shown in Table 1.

[0311] Furthermore, utilizing the Japanese Patent Application Publication No. 2022-158915... Figure 8 The particle attachment device described herein sprays an aerosol containing a slurry of ceramic particles (material: cordierite, median particle size: 3μm) and silica sol (silica concentration 20% by mass, median particle size 80nm) in a mass ratio of cordierite:silica = 9:1 at a predetermined time towards the center of the bottom surface of the entrance side of the honeycomb structure, in a direction perpendicular to the bottom surface of the entrance side, so that the ceramic particles adhere to the surface of the partition wall inside the entrance pores.

[0312] Then, the ceramic particles attached to the bottom surface of the entrance of the honeycomb structure are removed by vacuum. The honeycomb structure is then placed in an electric furnace and heated in an atmospheric atmosphere at a maximum temperature of 800°C for 1 hour. This forms a trapping layer as a sound-absorbing layer on the surface of the partition wall inside the entrance pore.

[0313] For the sound-absorbing layer of the honeycomb structure filter obtained by the above manufacturing method, the average thickness, average pore size, and average porosity were measured using the same method. The results are shown in Table 1. The honeycomb structure F differs from the honeycomb structure A mainly in its pore structure and the average thickness of its partitions. The pore structure of the honeycomb structure F, except for the structures adjacent to the outer peripheral sidewalls, includes... Figure 6C The diagram shows a structure where the entrance cells are adjacent to each other. It should be noted that the required number of honeycomb structures were fabricated to implement various performance evaluations.

[0314] (1-12. Cellular Structure G)

[0315] Using the same raw material composition as honeycomb structure A, the clay is extruded and shaped using a die with a honeycomb molding mechanism to obtain a honeycomb molded body with an overall cylindrical shape.

[0316] Next, the honeycomb molded body is dried using a microwave dryer, and then further dried using a hot air dryer. Finally, the two ends of the honeycomb molded body are cut off and adjusted to the predetermined size.

[0317] Next, a slurry for forming the sealing portions is prepared using the same material as the honeycomb molded body. Then, using the slurry, sealing portions are formed at the openings of predetermined cells on the inlet bottom side and the openings of remaining cells on the outlet bottom side of the dried honeycomb molded body. Specifically, the inlet cells sealed on the outlet side and the outlet cells sealed on the inlet side are alternately adjacent and arranged in a regular pattern.

[0318] Next, the honeycomb molded body with each sealing section was degreased in an atmospheric atmosphere at approximately 200–1000°C, and then fired in an atmospheric atmosphere at approximately 1410–1440°C to produce a wall-flow honeycomb structure. The resulting honeycomb structure had a cordierite content of over 95% by mass in the septa and outer peripheral sidewalls, and was cylindrical with a circular inlet and outlet bottom surface. Various properties of the resulting honeycomb structure were measured as before. The results are shown in Table 1.

[0319] Furthermore, utilizing the Japanese Patent Application Publication No. 2022-158915... Figure 8 The particle attachment device described herein sprays an aerosol containing a slurry of ceramic particles (material: cordierite, median particle size: 3μm) and silica sol (silica concentration 10% by mass, median particle size 80nm) at a predetermined time in a direction perpendicular to the bottom surface of the entrance side of the honeycomb structure, facing the center of the bottom surface of the entrance side, so that the ceramic particles adhere to the surface of the partition wall inside the entrance pores.

[0320] Then, the ceramic particles attached to the bottom surface of the entrance of the honeycomb structure are removed by vacuum. The honeycomb structure is then placed in an electric furnace and heated in an atmospheric atmosphere at a maximum temperature of 800°C for 1 hour. This forms a trapping layer as a sound-absorbing layer on the surface of the partition wall inside the entrance pore.

[0321] For the sound-absorbing layer of the honeycomb structure filter obtained by the above manufacturing method, the average thickness, average pore size, and average porosity were measured using the same method. The results are shown in Table 1. The main difference between honeycomb structure F and honeycomb structure A is the average thickness of the partition walls. It should be noted that the required number of honeycomb structures were fabricated for various performance evaluations.

[0322] (1-13. Cellular structure G')

[0323] Apart from changing the size and volume, the wall flow type of the honeycomb structure is obtained by following the same steps as the honeycomb structure G.

[0324] (1-14. Honeycomb Structure H)

[0325] Using the same raw material composition as honeycomb structure A, the clay is extruded and shaped using a die with a honeycomb molding mechanism to obtain a honeycomb molded body with an overall cylindrical shape.

[0326] Next, the honeycomb molded body is dried using a microwave dryer, and then further dried using a hot air dryer. Finally, the two ends of the honeycomb molded body are cut off and adjusted to the predetermined size.

[0327] Next, a slurry for forming the sealing portions is prepared using the same material as the honeycomb molded body. Then, using the slurry, sealing portions are formed at the openings of predetermined cells on the inlet bottom side and the openings of remaining cells on the outlet bottom side of the dried honeycomb molded body.

[0328] Next, the honeycomb molded body with each sealing section was degreased in an atmospheric atmosphere at approximately 200–1000°C, and then fired in an atmospheric atmosphere at approximately 1410–1440°C to produce a wall-flow honeycomb structure. The resulting honeycomb structure had a cordierite content of over 95% by mass in the septa and outer peripheral sidewalls, and was cylindrical with a circular inlet and outlet bottom surface. Various properties of the resulting honeycomb structure were measured as before. The results are shown in Table 1.

[0329] Furthermore, utilizing the Japanese Patent Application Publication No. 2022-158915... Figure 8 The particle attachment device described herein sprays an aerosol containing a slurry of ceramic particles (material: cordierite, median particle size: 3μm) and silica sol (silica concentration 10% by mass, median particle size 80nm) at a predetermined time in a direction perpendicular to the bottom surface of the entrance side of the honeycomb structure, facing the center of the bottom surface of the entrance side, so that the ceramic particles adhere to the surface of the partition wall inside the entrance pores.

[0330] Then, the ceramic particles attached to the bottom surface of the entrance of the honeycomb structure are removed by vacuum. The honeycomb structure is then placed in an electric furnace and heated in an atmospheric atmosphere at a maximum temperature of 800°C for 1 hour. This forms a trapping layer as a sound-absorbing layer on the surface of the partition wall inside the entrance pore.

[0331] For the sound-absorbing layer of the honeycomb structure filter obtained by the above manufacturing method, the average thickness, average pore size, and average porosity were measured using the same method. The results are shown in Table 1. The main difference between honeycomb structure H and honeycomb structure A is the opening shape and opening area of ​​the inlet and outlet pores. It should be noted that the required number of honeycomb structures were fabricated for various performance evaluations.

[0332] (1-15. Honeycomb structure H')

[0333] Apart from changing the size and volume, the wall flow type of the honeycomb structure is obtained by following the same steps as the honeycomb structure H.

[0334] (1-16. Honeycomb Structure I)

[0335] Using the same raw material composition as honeycomb structure A, the clay is extruded and shaped using a die with a honeycomb molding mechanism to obtain a honeycomb molded body with an overall cylindrical shape.

[0336] Next, the honeycomb molded body is dried using a microwave dryer, and then further dried using a hot air dryer. Finally, the two ends of the honeycomb molded body are cut off and adjusted to the predetermined size.

[0337] Next, a slurry for forming the sealing portions is prepared using the same material as the honeycomb molded body. Then, using the slurry, sealing portions are formed at the openings of predetermined cells on the inlet bottom side and the openings of remaining cells on the outlet bottom side of the dried honeycomb molded body. Specifically, the inlet cells sealed on the outlet side and the outlet cells sealed on the inlet side are alternately adjacent and arranged in a regular pattern.

[0338] Next, the honeycomb molded body with each sealing section is degreased in an atmospheric atmosphere at approximately 200-1000°C, and then fired in an atmospheric atmosphere at approximately 1410-1440°C to produce a wall-flow honeycomb structure. The resulting honeycomb structure has a cordierite content of over 95% by mass in the partitions and outer peripheral sidewalls, and is cylindrical with a circular bottom surface at the inlet and outlet.

[0339] For the obtained cellular structures, various properties were measured in the same manner as before. The results are shown in Table 1. The main difference between cellular structure I and cellular structure A is the presence or absence of a sound-absorbing layer. It should be noted that the required number of cellular structures were fabricated for the various property evaluations.

[0340] (1-17. Honeycomb Structure J)

[0341] Apart from changing the size and volume, the wall flow type of the honeycomb structure is obtained by following the same steps as the honeycomb structure J.

[0342] (1-18. Cellular Structure K)

[0343] Apart from changing the size and volume, the wall flow type of the honeycomb structure is obtained by following the same steps as the honeycomb structure J.

[0344] (1-19. Honeycomb Structure O)

[0345] Apart from changing the size and volume, the wall flow type of the honeycomb structure is obtained by following the same steps as the honeycomb structure H.

[0346] [Table 1]

[0347]

[0348] <2. Manufacturing of the Second Cellular Structure>

[0349] (2-1. Cellular structure L)

[0350] Using the same raw material composition as honeycomb structure A, the clay is extruded and shaped using a die with a honeycomb molding mechanism to obtain a honeycomb molded body with an overall cylindrical shape.

[0351] Next, the honeycomb molded body is dried using a microwave dryer, and then further dried using a hot air dryer. The two ends of the honeycomb molded body are then cut off and adjusted to the predetermined dimensions. Next, without forming sealing sections, it is degreased in an atmospheric atmosphere at approximately 200–1000°C, and then fired in an atmospheric atmosphere at approximately 1410–1440°C to produce a flow-through honeycomb structure. The resulting honeycomb structure has a cordierite content of over 95% by mass in the septa and outer peripheral sidewalls, and is cylindrical with a circular inlet and outlet bottom surface.

[0352] For the obtained honeycomb structures, various properties were measured in the same manner as before. The results are shown in Table 2. It should be noted that the required number of honeycomb structures were fabricated to perform the various property evaluations.

[0353] Furthermore, a ternary catalyst is supported on the pores of the obtained honeycomb structure. Specifically, a predetermined amount of catalyst slurry containing platinum (Pt), rhodium (Rh), and palladium (Pd) in a mass ratio of 1:0.5:4 (Pt:Rh:Pd) and primarily composed of alumina and cerium dioxide is introduced into all pores of the honeycomb structure using a suction method. The catalyst contained in the catalyst slurry is sintered onto the partition walls under atmospheric conditions at 600°C for 1 hour, forming a catalyst layer on the surface of the partition walls within the pores. The amount of catalyst is set to 200 g per liter of honeycomb catalyst support. The method for determining the amount of catalyst is as described above. In addition, the content of the aforementioned precious metals (Pt, Rh, Pd) in the ternary catalyst is set to 2 g per liter of honeycomb catalyst support when the ternary catalyst is supported on the honeycomb catalyst support.

[0354] (2-2. Honeycomb structure M)

[0355] Aside from changing the size and volume, a flow-through honeycomb structure carrying the catalyst was obtained by following the same steps as the honeycomb structure L.

[0356] (2-3. Cellular Structure N)

[0357] Aside from changing the size and volume, a flow-through honeycomb structure carrying the catalyst was obtained by following the same steps as the honeycomb structure L.

[0358] [Table 2]

[0359]

[0360] <3. Sound Absorption Performance of Honeycomb Structures>

[0361] For the wall-flow type and flow-through type honeycomb structures manufactured as described above, the sound attenuation was measured at 25°C and atmospheric pressure when a 1kHz sound generated by a sound source speaker located on the bottom side of the inlet was measured at the bottom side of the outlet. The measurement procedure and conditions are as described above. As a noise meter, a RION NL-53 manufactured by RION Corporation, conforming to JIS C1509-1:2017, Class 1, was used. The results are shown in Tables 1 and 2.

[0362] <4. Noise reduction performance when installed in a vehicle>

[0363] Imagine Figure 7The exhaust gas system shown, which discharges exhaust gas from the internal combustion engine 13 through a second honeycomb structure 200, a first honeycomb structure 100, and mufflers (auxiliary muffler 301 and main muffler 302) arranged in series, was used to simulate and calculate the noise reduction performance using MSC Nastran's Finite Element Analysis (FEA) software. During the simulation, the following conditions were changed according to the test number.

[0364] • Displacement of internal combustion engines

[0365] (Assuming the gasoline engine is used as an internal combustion engine, the initial noise level varies depending on the engine's displacement. With a displacement of 1500cm³...) 3 The initial sound pressure level was set to 110 dB, with an exhaust volume of 1000 cm³. 3 The initial sound pressure level was set to 105 dB, and the initial sound pressure level of the engine was suppressed to 92 dB within the casing with the muffler completely removed.

[0366] • Setting of the first cell structure (rear cell)

[0367] (Assuming that any of the wall-flow type honeycomb structures manufactured above are installed in the exhaust gas system, the above-mentioned noise reduction performance is used for simulation. In addition, according to the test number, a simulation is performed in the case where no wall-flow type honeycomb structure is installed.)

[0368] • Setting of the second cell structure (front cell)

[0369] (Assuming that any of the above-described flow-through honeycomb structures is installed in the exhaust gas system, the above-described noise reduction performance is used for simulation. In addition, according to the test number, a simulation is performed in the case where no flow-through honeycomb structure is installed.)

[0370] • Muffler settings

[0371] (The noise reduction performance of the auxiliary and main mufflers is assumed to be based on the volume of a typical multi-stage muffler.)

[0372] The simulation was conducted under the following conditions, assuming the noise level measured at the exhaust port was determined. The simulation was conducted under the following conditions: in an anechoic chamber at 25°C and atmospheric pressure, while the vehicle was stationary, the noise level at a position 0.5m above the center of the exhaust port 143 at a 45° angle relative to the direction of the exhaust flow, was measured using a noise meter of Class 1, suitable for JIS C1509-1:2017, when the internal combustion engine 13 was running at its rated speed.

[0373] The simulation conditions and results for each experiment number are shown in Table 3.

[0374] • The “total noise attenuation of the front cell and the back cell” is calculated by incorporating both and also including the effects of their mutual influence.

[0375] • The evaluation of "exhaust noise" is calculated by measuring the difference between the sound pressure level dB at the sound source and the sound pressure level dB at the exhaust port.

[0376] • The evaluation of “exhaust noise” shall be conducted according to the following criteria.

[0377] Acceptable: Less than 80dB

[0378] Not allowed: above 80dB

[0379] • For “compactness”, the following criteria shall be used for evaluation.

[0380] Possible: (H+M1+M2) / E is 3 or less

[0381] Not allowed: (H+M1+M2) / E exceeds 3

[0382] [Table 3-1]

[0383]

[0384] [Table 3-2]

[0385]

[0386] Based on the above results, it can be seen that the wall-flow honeycomb structure can be given a sound-absorbing function. Compared with the past, even if the volume of the silencer is reduced, or even if the silencer is eliminated, the desired sound-absorbing effect can still be achieved.

Claims

1. A vehicle comprising: a drive battery capable of supplying electricity to a motor serving as a power source for the vehicle; an internal combustion engine for generating electricity, used to charge the drive battery; and an exhaust gas system for discharging exhaust gases emitted from the internal combustion engine to the outside of the vehicle. The exhaust gas system includes: an exhaust gas flow path extending from the outlet of the internal combustion engine to the exhaust port; a wall-flow type first honeycomb structure, which combines silencing and exhaust gas purification functions, disposed midway through the exhaust gas flow path and may or may not carry a catalyst; and a muffler disposed midway through the exhaust gas flow path and downstream of the wall-flow type first honeycomb structure. The first honeycomb structure of the wall-flow type has: an outer peripheral sidewall; a plurality of inlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having an opening at the bottom surface of the inlet and a sealing portion at the bottom surface of the outlet; and a plurality of outlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having a sealing portion at the bottom surface of the inlet and an opening at the bottom surface of the outlet, and being adjacent to at least one of the plurality of inlet cells by a porous partition wall. Let the displacement of the internal combustion engine be E (cm). 3 Let the total volume of the muffler be M (cm³). 3 When ), equation (1) is satisfied: 0≤M / E≤1.5···Equation (1) Furthermore, in a silencing chamber at 25°C and atmospheric pressure, during the charging of the drive battery by the internal combustion engine while the vehicle is stationary, the noise level at a position 0.5m away from the center of the exhaust port at a 45° angle relative to the direction of the exhaust flow when the internal combustion engine is running at its rated speed is below 80dB.

2. A vehicle comprising: a drive battery capable of supplying electricity to a motor serving as a power source for the vehicle; an internal combustion engine for generating electricity, used to charge the drive battery; and an exhaust gas system for discharging exhaust gases emitted from the internal combustion engine to the outside of the vehicle. The exhaust gas system includes: an exhaust gas flow path extending from the outlet of the internal combustion engine to the exhaust port; a wall-flow type first honeycomb structure, which combines silencing and exhaust gas purification functions, disposed midway through the exhaust gas flow path and may or may not carry a catalyst; and a muffler disposed midway through the exhaust gas flow path and downstream of the wall-flow type first honeycomb structure. The first honeycomb structure of the wall-flow type has: an outer peripheral sidewall; a plurality of inlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having an opening at the bottom surface of the inlet and a sealing portion at the bottom surface of the outlet; and a plurality of outlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having a sealing portion at the bottom surface of the inlet and an opening at the bottom surface of the outlet, and being adjacent to at least one of the plurality of inlet cells by a porous partition wall. Let the displacement of the internal combustion engine be E (cm). 3 Let the total volume of the first honeycomb structure of the wall flow type be H (cm³). 3 Let the total volume of the muffler be M (cm³). 3 When ), equations (1) and (2) are satisfied: 0≤M / E≤1.5···Equation (1) 1.0≤(M+H) / E≤4.0···Equation (2) Furthermore, when the sound of a 1kHz sound source loudspeaker located on the bottom side of the inlet is measured at 25°C and atmospheric pressure, the sound attenuation of the first honeycomb structure of the wall flow type is greater than 9dB.

3. A vehicle comprising: a drive battery capable of supplying electricity to a motor serving as a power source for the vehicle; an internal combustion engine for generating electricity, used to charge the drive battery; and an exhaust gas system for discharging exhaust gases emitted from the internal combustion engine to the outside of the vehicle. The exhaust gas system includes: an exhaust gas flow path extending from the outlet of the internal combustion engine to the exhaust port; and a wall-flow type first honeycomb structure, which combines silencing and exhaust gas purification functions, disposed midway through the exhaust gas flow path, and may or may not carry a catalyst. The exhaust gas system does not have a muffler. The first honeycomb structure of the wall-flow type has: an outer peripheral sidewall; a plurality of inlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having an opening at the bottom surface of the inlet and a sealing portion at the bottom surface of the outlet; and a plurality of outlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having a sealing portion at the bottom surface of the inlet and an opening at the bottom surface of the outlet, and being adjacent to at least one of the plurality of inlet cells by a porous partition wall. Let the displacement of the internal combustion engine be E (cm). 3 Let the total volume of the first honeycomb structure of the wall flow type be H (cm³). 3 When ), equation (3) is satisfied: 0.8≤H / E≤2.0···Equation (3) Furthermore, in a silencing chamber at 25°C and atmospheric pressure, during the charging of the drive battery by the internal combustion engine while the vehicle is stationary, the noise level at a position 0.5m away from the center of the exhaust port at a 45° angle relative to the direction of the exhaust flow when the internal combustion engine is running at its rated speed is below 80dB.

4. A vehicle comprising: a drive battery capable of supplying electricity to a motor serving as a power source for the vehicle; an internal combustion engine for generating electricity, used to charge the drive battery; and an exhaust gas system for discharging exhaust gases emitted from the internal combustion engine to the outside of the vehicle. The exhaust gas system includes: an exhaust gas flow path extending from the outlet of the internal combustion engine to the exhaust port; and a wall-flow type first honeycomb structure, which combines silencing and exhaust gas purification functions, disposed midway through the exhaust gas flow path, and may or may not carry a catalyst. The exhaust gas system does not have a muffler. The first honeycomb structure of the wall-flow type has: an outer peripheral sidewall; a plurality of inlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having an opening at the bottom surface of the inlet and a sealing portion at the bottom surface of the outlet; and a plurality of outlet cells disposed on the inner peripheral side of the outer peripheral sidewall, extending from the bottom surface of the inlet to the bottom surface of the outlet, having a sealing portion at the bottom surface of the inlet and an opening at the bottom surface of the outlet, and being adjacent to at least one of the plurality of inlet cells by a porous partition wall. Let the displacement of the internal combustion engine be E (cm). 3 Let the total volume of the first honeycomb structure of the wall flow type be H (cm³). 3 When ), equation (3) is satisfied: 0.8≤H / E≤2.0···Equation (3) Furthermore, when the sound of a 1kHz sound source loudspeaker located on the bottom side of the inlet is measured at 25°C and atmospheric pressure, the sound attenuation of the first honeycomb structure of the wall flow type is greater than 9dB.

5. The vehicle according to any one of claims 1 to 4, wherein, The exhaust gas system also has a flow-through type second honeycomb structure carrying a catalyst on the upstream side of the first honeycomb structure of the wall flow type.

6. The vehicle according to claim 5, wherein, The first honeycomb structure of the wall flow type and the second honeycomb structure of the flow type respectively support ternary catalysts.

7. The vehicle according to any one of claims 1 to 4, wherein, The exhaust gas system does not have a flow-through second honeycomb structure.

8. The vehicle according to any one of claims 1 to 4, wherein, The first honeycomb structure of the wall flow type satisfies one or more of the following conditions (A) to (E). (A) The surface of the partition is covered with a sound-absorbing layer. Here, the average thickness of the sound-absorbing layer is more than 1% and less than 30% of the average thickness of the partition wall; the average pore size of the sound-absorbing layer is smaller than the average pore size of the partition wall, being more than 0.1 μm and less than 5 μm; the average porosity of the sound-absorbing layer is more than 35% and less than 90%; and the sound-absorbing layer is located in one or both of the plurality of inlet or outlet orifices. (B) The opening area of ​​the opening is different between at least one of the plurality of inlet cells and at least one of the plurality of outlet cells adjacent to the inlet cell. (C) The average thickness of the partition wall is 0.12 mm or more. (D) A catalyst is supported inside the pores of the partition wall, and the amount of catalyst, in terms of alumina content, is 20 g / L to 150 g / L relative to the volume of the first honeycomb structure of the wall flow type. (E) At least one of the plurality of inlet cells is sandwiched between the porous material partition and adjacent to at least one of the plurality of inlet cells, and adjacent to at least one of the plurality of outlet cells.

9. The vehicle according to any one of claims 1 to 4, wherein, The first honeycomb structure of the wall flow pattern is made of ceramic.

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